Source: https://patents.google.com/patent/JP4003363B2/en
Timestamp: 2020-01-28 05:03:54
Document Index: 192059050

Matched Legal Cases: ['art 221', 'art 220', 'art 221', 'art 1', 'art 221', 'art 221', 'art 221', 'art 220', 'art 221', 'art 201', 'art 320', 'art 330', 'art 320', 'art 320', 'art 330', 'art 330', 'art) 221', 'art 303', 'art 221', 'art 360', 'art 200', 'art, 500']

JP4003363B2 - Combustion pressure sensor structure - Google Patents
Combustion pressure sensor structure Download PDF
JP4003363B2
JP4003363B2 JP36645799A JP36645799A JP4003363B2 JP 4003363 B2 JP4003363 B2 JP 4003363B2 JP 36645799 A JP36645799 A JP 36645799A JP 36645799 A JP36645799 A JP 36645799A JP 4003363 B2 JP4003363 B2 JP 4003363B2
JP36645799A
JP2001182585A (en
光一 服部
1999-12-24 Application filed by 株式会社デンソー filed Critical 株式会社デンソー
2001-07-06 Publication of JP2001182585A publication Critical patent/JP2001182585A/en
2007-11-07 Publication of JP4003363B2 publication Critical patent/JP4003363B2/en
The present invention includes a structure (for example, a glow plug, a spark plug, a bolt, and the like) that is screwed by inserting one end side into a screw hole formed in an engine and rotating it around an axis, The present invention relates to a combustion pressure sensor structure including a combustion pressure sensor attached to an intermediate portion in the axial direction.
As this type of combustion pressure sensor structure, for example, a glow plug with a combustion pressure sensor, which is used as a starting assist device in an engine such as a diesel engine as described in Japanese Patent Laid-Open No. 7-139736, has been proposed. Yes. A general structure of a conventional glow plug with a combustion pressure sensor is shown in FIG. 14B shows the outer peripheral shape when the hexagonal portion 201b of the housing 201 in FIG. 14A is viewed from above, and is shown in a form compared with the combustion pressure sensor 30. FIG.
The glow plug J1 with a combustion pressure sensor includes a plug main body (glow plug alone) 200 as a structure formed by holding a heating element 206 that generates heat when energized in a housing 201, and a plug main body attached to the plug main body 200. A configuration provided with a combustion pressure sensor (pressure sensor) 30 for detecting the combustion pressure of the engine based on the force accompanying the combustion pressure acting on the unit 200 and a lead wiring 500 for taking out the signal of the combustion pressure sensor 30 to the outside. Have.
The plug body 200 is screwed by inserting one end into a screw hole 1b formed in the engine head 1 of the diesel engine. This screw connection is made by a mounting screw 201a formed on the outer peripheral surface of the housing 201 of the plug main body 200, and the screw tightening is performed via a hexagonal portion 201b formed on the other end side of the housing 201. This is done by rotating around the axis.
The function of the glow plug J1 as an ignition plug is as follows. That is, a voltage is applied to the middle shaft 204 from a power source (not shown) via the connecting bar 2 and grounded to the engine head 1 via the heating coil 203, the sheath tube 202, and the housing 201. As a result, the heating element 206 constituted by the heating coil 203 and the sheath tube 202 generates heat and can assist ignition start of the diesel engine.
The combustion pressure sensor 30 has an annular shape having a screw portion 311 on the inner surface of the through hole 30a. The plug main body portion 200 is inserted into the through hole 30a and is fixed to the mounting screw 201a of the plug main body portion 200 by screw coupling. ing. In addition, one end of the lead wiring 500 is electrically connected to the upper end surface of the combustion pressure sensor 30 via a fixing bracket 333, and a connector 400 for connecting to an external terminal is provided on the other end, and a sensor signal is provided. Can be taken out to the outside (such as an ECU of a vehicle).
And the detection method of a combustion pressure is as follows. The combustion pressure generated in the combustion chamber 1a is transmitted to the mounting screw 201a via the heating element 206 and the housing 201, and the housing 201 is pushed up in the axial direction of the screw hole 1b and slightly displaced. The load on the pressure sensor 30 is reduced. A combustion pressure is detected by converting the load fluctuation into an electric signal by the sensor 30 and outputting the electric signal.
A procedure for mounting the glow plug J1 with the combustion pressure sensor will be described with reference to FIGS. The combustion pressure sensor 30 is inserted in advance along the mounting screw 201a of the housing 201 of the plug main body 200 and temporarily mounted. At this time, since the outer diameter of the hexagonal portion 201b of the plug main body 200 is larger than the inner diameter of the through hole 30a of the combustion pressure sensor 30, as shown in FIG. Inserted into the through hole 30a of the combustion pressure sensor 30 from the insertion side into the hole 1b).
In this state, the plug main body portion 200 is inserted into the screw hole 1b of the engine head 1, and the hexagonal portion 201b is rotated around the axis using the plug wrench 900 (see FIG. 15). Tighten only to hold and fix. Thereafter, by using a socket wrench 910 dedicated to the combustion pressure sensor (see FIG. 16), the hexagonal portion 312 of the nut of the combustion pressure sensor 30 is rotated around the axis along the mounting screw 201a of the housing 201 and tightened. A lower end surface of the combustion pressure sensor 30 is held and fixed to a seating surface (surface) 1 e of the engine head 1.
However, according to the study by the present inventors, it has been found that the following problem arises in the conventional procedure for mounting the glow plug with combustion pressure sensor J1. The hexagonal portion (nut portion) 201b of the plug main body portion 200 into which the plug wrench 900 is inserted, the lead wiring 500 of the combustion pressure sensor 30, and the fixing bracket 333 are arranged as close as possible.
In addition, the reason for the close placement is that the upper end surface of the hexagonal portion 312 of the combustion pressure sensor 30 and the upper end surface of the hexagonal portion 201b of the plug main body portion 200 are close to each other, that is, the other portion of the plug main body portion 200. As the length of the part that is opened without being held and fixed by the member is shorter, mechanical vibration noise (for example, 5 kHz or less) generated by the plug main body 200 itself is added to the combustion pressure detected by the combustion pressure sensor 30. This is because it can be reduced. This close arrangement is an important factor that cannot be compromised in terms of performance.
Therefore, when the plug wrench 900 is fitted into the hexagonal portion 201b during the tightening operation of the plug main body 200, the tip of the plug wrench 900 comes into contact with the lead wire 500 and the lead wire 500 is bent. Alternatively, a disconnection due to a dent or a defect such as deformation or breakage of the fixing bracket 333 may occur.
Therefore, when the plug main body 200 is mounted using the plug wrench 900, it is assumed that the plug wrench 900 and the lead wiring 500 of the combustion pressure sensor 30 interfere with each other, and that the lead wiring 500 and the connector 400 are entangled with parts around the engine. However, it is necessary to work carefully and carefully. Also, an air impact wrench with excellent mounting workability cannot be used.
As described above, when the conventional glow plug J1 with the combustion pressure sensor is mounted, there is a problem in both workability and work efficiency due to the influence of the lead wiring 500 connected to the combustion pressure sensor 30. Such a problem is not only a glow plug with a combustion pressure sensor, but also a structure that is screw-coupled by inserting one end into a screw hole formed in the engine and rotating it around an axis, A combustion pressure sensor structure (hereinafter simply referred to as a combustion pressure sensor structure) including a combustion pressure sensor attached to the body is considered to be a common problem.
Therefore, in view of the above circumstances, the present invention has an object of improving workability without being affected by lead wiring connected to a combustion pressure sensor when a combustion pressure sensor structure is formed.
In order to achieve the above object, according to the first aspect of the present invention, in the combustion pressure sensor structure, the nut portion (220, 700, 800) of the structure (220, 700, 800) inserted into the screw hole (1b) of the engine from one end side. 221, 701 b, 801 b) on the other end side is made smaller than the inner diameter of the through holes (31 a to 37 a) of the combustion pressure sensor (31 to 37), and from the other end side of the structure The combustion pressure sensor can be inserted through a through hole.
Conventionally, when the structure has a nut portion, the nut portion is large, and therefore, it can only be inserted into the through hole of the combustion pressure sensor from the end portion (one end side) opposite to the nut portion. In that respect, in the present invention, since it can be inserted also from the end portion (the other end side) on the nut portion side, the sensor can be attached to the structure after screwing the structure into the screw hole of the engine. It is not affected by the connected lead wiring. Therefore, workability can be improved in forming the combustion pressure sensor structure.
According to a third aspect of the present invention, in the combustion pressure sensor structure, the lead wiring (305, 500) for taking out the signal of the combustion pressure sensor (33-35, 37) to the outside is provided to the combustion pressure sensor. It is characterized by being removable.
As a result, since the lead wiring is detachable from the combustion pressure sensor, the lead wiring can be retrofitted to the combustion pressure sensor after the structure (200, 220, 700, 800) is screwed to the screw hole (1b) of the engine. When the combustion pressure sensor structure is formed, the workability can be improved without being affected by the lead wiring connected to the combustion pressure sensor. As in the fourth aspect of the present invention, the lead wiring (305, 500) can be attached to and detached from the combustion pressure sensor (33-35, 37) by screw connection.
Also , Burning Pressure sensor ( 33-35, 37 ) In which the structure (200, 220, 700, 800) is inserted ( 33a-35a, 37a ) Is formed on the inner surface of the structure, and the screw portion (201a, 701a, 801a) of the structure and the screw portion of the through hole are screw-coupled to fix the combustion pressure sensor to the structure. (Claim 2 and claim 2) 3 Invention).
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below. In the following embodiments, the combustion pressure sensor structure of the present invention is described as being embodied in a glow plug with a combustion pressure sensor. 1 to 16, the same reference numerals are assigned to the same parts.
FIG. 1 is a partial longitudinal sectional view showing an overall outline of a glow plug 100 with a combustion pressure sensor according to the present embodiment attached to an engine head 1 of a diesel engine. 2A is an external view of the upper surface of the engine head 1 in the glow plug 100 in FIG. 1, and FIG. 2B is a top view of the hexagonal part 221 of the housing 201 alone. It is shown together with the pressure sensor 31.
The glow plug 100 is also largely similar to the conventional glow plug with combustion pressure sensor J1 shown in FIG. 14 described above, a plug main body (structure in the present invention, a single glow plug) 220, and a combustion pressure sensor. 31 and a lead wire (lead wiring referred to in the present invention) 500. The plug main body 220 of the present embodiment is different from the plug main body 200 in the above-described conventional product in that the portion protruding from the engine head 1, that is, the other end side (hexagonal portion 221 side) of the housing 201 is changed. .
The engine head 1 is made of, for example, an aluminum alloy or iron, and the engine head 1 is formed with a screw hole (plug hole, attachment hole) 1b penetrating from the outer surface to the internal combustion chamber 1a. The plug body portion (structure) 220 is firmly screwed into the screw hole 1b by inserting one end side (the lower side in FIG. 1) of the plug body portion (structure) 220. Here, the housing 201 provided in the plug main body 220 has a hollow pipe shape made of metal (low carbon steel or the like).
On the outer peripheral surface of the housing 201, a mounting screw (a screw portion of the structure in the present invention) 201a for screw connection with the screw hole 1b is formed, and the other end side (upper side in FIG. 1) of the housing 201 is formed. ) Is formed with a hexagonal portion (a nut portion of the structure referred to in the present invention) 221 for applying a rotational force around the axis to perform the screw connection. And the plug main-body part 220 is being fixed to this screw hole 1b by rotating about the axis via the hexagonal part 221, and screwing the attachment screw 201a with the screw part 1c of the screw hole 1b.
Also in the present embodiment, the combustion pressure sensor 31 has a substantially annular shape having a screw portion 311 (see FIG. 3 described later) on the inner surface of the through hole 31a. Then, the plug main body (structure) 220 is inserted into the through hole 31a of the sensor 31, and is fixed to the mounting screw 201a of the plug main body 220 by screw connection. Thus, as shown in FIG. 1, the combustion pressure sensor 31 is fixed to the outer peripheral surface of the projecting portion at a portion projecting in the axial direction from the surface of the engine head 1 in the plug main body 220. It is disposed in contact with the seating surface (surface) 1e.
Here, as a unique configuration of the present embodiment, the outer diameter of the other end side including the hexagonal portion (nut portion) 221 of the plug body portion (structure) 220 is the inner diameter of the through hole 31a of the combustion pressure sensor 31 ( It is smaller than the screw inner diameter 311a) shown in FIG. 2 (b), and the plug main body 220 can be inserted into the through hole 31a of the combustion pressure sensor 31 from the other end side. Details of this configuration will be described in comparison with the conventional product J1 shown in FIG.
First, in the conventional product J1 shown in FIG. 14, for example, when the mounting screw 201a of the plug main body 200 is a male screw of M10 and a pitch of 1.25 mm, the screw portion 311 on the inner surface of the through hole 30a in the combustion pressure sensor 30 is M10 is a female screw having a pitch of 1.25 mm that can be screwed to the male screw. Here, the minimum diameter of the screw portion 311 in which the female screw of the sensor 30 is formed, that is, the screw inner diameter 311a is, for example, φ8.7 mm.
In the conventional product J1, all the parts of the plug main body 200 from the mounting screw 201a of the housing 201 to the heating element 206 side (one end side) are configured with an outer diameter less than the screw inner diameter 311a of the combustion pressure sensor 30. Therefore, it is naturally possible to insert the combustion pressure sensor 30 from the heating element 206 side.
However, on the other end side of the plug main body 200, a standardized hexagonal portion 201b having an outer diameter larger than the screw inner diameter 311a of the combustion pressure sensor 30 is formed at the end of the housing 201 (FIG. 14B). )reference). For example, in the conventional hexagonal portion 201b, the hexagonal two-sided width 201c is 12 mm, and the distance between the opposing apex angles (distance between apex angles) 201d is 13.8 mm. Therefore, conventionally, insertion into the sensor 30 from the hexagonal portion 201b side is impossible.
Thus, in the conventional product J1, it is impossible to insert the combustion pressure sensor 30 from the end face side of the hexagonal portion 201b of the plug main body portion 200, whereas in the present embodiment, the hexagonal portion 221 of the plug main body portion 220. The combustion pressure sensor 31 can be inserted from the end face side (the other end side).
That is, as shown in FIG. 2, in the present embodiment, the apex distance 221 b that is the maximum outer shape of the hexagonal part 221 in the plug main body 220 is set to be less than the screw inner diameter 311 a of the combustion pressure sensor 31 and from the hexagonal part 221. All the outer diameter dimensions of the portion of the housing 201 reaching the mounting screw 201a are also less than the screw inner diameter 311a of the sensor 31. Thus, the combustion pressure sensor 31 can be easily fitted and attached from the other end side of the plug body 220 after the plug body 220 is attached to the engine head 1 alone.
Incidentally, the dimension of the hexagonal part 221 of the plug main body part 220 of this embodiment can be performed as follows. Here, in order to sufficiently secure the hexagonal two-sided width 221a that is a substantial catching part corresponding to the plug wrench, the hexagonal two-sided width 221a is newly unified to 8 mm, which is being considered for standardization to ISO, The distance 221b is, for example, less than φ8.7 mm, which is smaller than the screw inner diameter 311a of φ8.7 mm, for example, as a shape that removes the acute angle portion of the apex angle. Also, the outer diameter of the part from the hexagonal part 221 to the mounting screw part 201a was all less than φ8.7 mm.
As described above, the present embodiment is characterized in that the hexagonal portion 221 of the housing 201 and the peripheral configuration thereof are reduced in diameter, but the inside of the reduced diameter housing 201 is also devised. First, in the conventional product J1, as shown in FIG. 14, a washer 207 made of an insulating bakelite material and an O-ring 208 made of silicon or fluorine rubber are inserted into the middle shaft 204 inside the upper end side of the housing 201. Has been placed. Here, the washer 207 is for the purpose of holding the O-ring 208 and centering the center shaft 204, and the O-ring 208 is for the purpose of ensuring waterproof and airtightness in the housing 201.
In the conventional product J1, the intermediate shaft 204 is fixed to the housing 201 by a fixing nut 210 along a terminal screw 204a provided on the intermediate shaft 204 with an insulating bush 209 made of an insulating resin such as phenol interposed therebetween. Yes. Here, the insulating bush 209 also has a function of preventing a short circuit caused by contact between the center shaft 204 and the housing 201.
In contrast to the configuration in the housing of the conventional product J1, in this embodiment, the inner shaft 224, the insulating bush 229, and the fixing nut 230 are reduced in diameter inside the reduced-diameter housing 201. Further, the airtight rubber 228 is a tapered molded rubber, so that the center shaft 224 can be centered and the waterproof and airtightness in the housing 201 can be secured, and the O-ring 208 and the washer 207 used conventionally can be eliminated. Some simplification is achieved.
As described above, the hexagonal portion 221 and the portion related to the hexagonal portion 221 that are the original configuration of the present embodiment have been described. Further, other portions of the glow plug 100 with the combustion pressure sensor will be described with reference to FIG.
The plug main body 220 includes a hollow pipe-shaped sheath tube 202 held in the housing 201. The sheath tube 202 is made of a heat-resistant / corrosion-resistant alloy (for example, stainless steel SUS310), and the distal end side (lower side in FIG. 1) is closed and the other end side (upper side in FIG. 1) is opened. A heating coil 203 made of resistance wires such as NiCr and CoFe is provided inside the distal end side of the sheath tube 202, and one end side of the above-described metal rod-shaped middle shaft 224 is partially inside the other end side of the sheath tube 202. Arranged in the inserted form.
One end of the heating coil 203 is coupled to the distal end side of the sheath tube 202, and the other end of the heating coil 203 is coupled to one end of the middle shaft 224. Further, between the heat generating coil 203 and the middle shaft 224 and the sheath tube 202, an insulating powder 205 such as magnesium oxide having heat resistance is filled.
In addition, the sheath tube 202 is subjected to drawing processing by swaging, thereby improving the density of the insulating powder 205 filled therein, and the sheath tube 202 and the central shaft 224 through the insulating powder 205. The heating coil 203 is firmly held and fixed.
Here, in a portion including the heat generating coil 203 in the sheath tube 202, the heat generating body 206 is configured by the sheath tube 202, the heat generating coil 203 and the insulating powder 205. The heating element 206 is joined and held inside the housing 201 so that the distal end portion (the distal end portion of the sheath tube 202) is exposed. The heating element 206 (the outer peripheral surface of the sheath tube 202) and the housing 201 can be joined by fixing by fitting press fitting or brazing such as silver brazing.
Further, although not shown, a connecting bar is fixed by a terminal nut and electrically connected to the terminal screw 204a provided on the other end side of the central shaft 224, as in FIG. This connecting bar is connected to a power source (not shown), and is grounded to the engine head 1 via the center shaft 224, the heating coil 203, the sheath tube 202, and the housing 201. Thereby, the heat generating element 206 generates heat in the glow plug 100, and it is possible to assist ignition start of the diesel engine.
In addition to the so-called metal heating element based on the metal resistance wire described above, the heating element 206 includes, for example, a heating element made of conductive ceramics containing silicon nitride and molybdenum silicide as components. A so-called ceramic heating element sintered in an encapsulating manner with an insulator made of an insulating ceramic may be used.
Next, in the present embodiment, as described above, the substantially annular combustion pressure sensor 31 is attached to the middle portion of the plug main body 220 in the axial direction by screw coupling. Since this combustion pressure sensor 31 is devised in detail as compared with the conventional sensor 30, its details will be described with reference to FIG. FIG. 3 is an enlarged view showing details of the combustion pressure sensor (pressure sensor) 31 in FIG. 1, (a) is a longitudinal sectional view, and (b) is a view taken in the direction of arrow A in (a). .
The combustion pressure sensor 31 is roughly composed of a nut (sensor fixing portion) 310 for attaching the sensor body to the plug body portion (structure) 220 and a piezoelectric device that generates an electric signal (charge) in accordance with the force accompanying the combustion pressure. The element part 320, a lead part 330 for taking out an electric signal generated in the piezoelectric element part 320 and guiding it to the lead wire 500, and the nut 310 together with the piezoelectric element part 320 and a part of the lead part 330 are fixed. And a metal case 350 for protecting the piezoelectric element 320 from dust and water.
First, the nut 310 and the lead part 330 will be described. The nut 310 is made of metal and includes the screw portion 311 and the hexagonal portion 312 for mounting and fixing the sensor body via the mounting screw 201 a of the housing 201, and is fixed to the outer periphery of the housing 201. In addition, a large-diameter portion 313 and a small-diameter portion 314 are sequentially formed on the lower side of the hexagonal portion 312, and a heat-shrinkable insulating tube 315 made of silicon is tightly fixed to the outer peripheral surface of the small-diameter portion 314. .
The lead portion 330 is a portion for electrically connecting the piezoelectric element portion 320 and one end side of the lead wire 500, and the electrode 331, the insulator 332, the fixing bracket 333, and one end side of the lead wire 500 are arranged as constituent elements thereof. As prepared. The electrode 331 is annular and is made of metal, and the insulator 332 is interposed between the electrode 331 and the nut 310 to insulate both the 331 and 310 from each other. The annular 331 is an insulating material such as mica or alumina. Made of material. The electrodes 331 and the insulator 332 are fitted into the outer edge of the small diameter portion 314 of the nut 310 covered with the insulating tube 315.
Here, the lead wire 500 is formed by sequentially laminating a conductive signal extraction line 501, an insulating insulating coating 502, a conductive ground shield wire 503, and an insulating insulating coating 504 from the innermost side to the outer side. The signal extraction line 501 and the ground side shield line 503 are electrically insulated. As shown in FIG. 3, the lead wire 500 has a configuration in which the signal extraction wire 501, the insulation coating 502, and the ground side shield wire 503 are partially exposed in order from the tip on one end side.
Then, on one end side of the lead wire 500, the signal extraction line 501 passes through the hole 316 formed in the nut 310 and the notch 332 a formed in the insulator 332, and then to the electrode 331 through the hole 331 a formed in the electrode 331. Welded and connected. The other end side of the lead wire 500 is connected to the connector 400 and is electrically connected to an external circuit (such as an ECU of the vehicle).
The fixing fitting 333 is for fixing the lead wire 500 to the nut 310 and has a hollow pipe shape, and is provided on the outer periphery on one end side of the lead wire 500. Here, the upper portion of the hole 316 formed in the nut 310 is configured as a fixing bracket holding hole 316a for holding the fixing bracket 333, and a part of the fixing bracket 333 is formed in the holding hole 316a. Insertion is fixed.
The fixing bracket 333 is fixed by caulking to the lead wire 500, and the ground side shield wire 503 and the fixing bracket 333 are electrically connected. The outer peripheral portion of the fixing metal 333 protruding from the fixing metal holding hole 316a is covered with a heat-shrinkable insulating coating 333a made of silicon.
Next, the piezoelectric element portion 320 has an annular shape corresponding to the small diameter portion 314 of the nut 310, and, like the electrode 331, along the outer peripheral surface of the small diameter portion 314 via the insulating tube 315. It is arranged. In the illustrated example, the piezoelectric element portion 320 has a laminated structure in which three layers of piezoelectric ceramics (piezoelectric elements) 321, a signal extraction side washer ring 322, and a ground side washer ring 323 are combined.
Each piezoelectric ceramic 321 has a disk ring shape with the same dimensions, and is made of lead titanate, lead zirconate titanate, or the like. Then, the three piezoelectric ceramics 321 are electrically connected in parallel, and the output sensitivities of these three piezoelectric ceramics 321 are added together, so that the sensitivity can be greatly improved.
Next, the pedestal 340 has a substantially annular shape made of metal, and a rotation stopper 341 is formed on the end surface on the contact side with the engine head 1. As shown in FIG. 3B, the rotation stopper 341 corresponds to the oval rotation stopper 317 formed at the end of the small diameter portion 314 of the nut 310, and easily fits into the rotation stopper 317. Make the same oval as possible. Thereby, the shift | offset | difference of the nut 310 and the base 340 around the axis | shaft of a plug can be prevented.
Further, a metal cylindrical metal case 350 made of, for example, SUS304 is provided on the outer edge of the pedestal 340, and the metal case 350 includes the outer periphery of the entire combustion pressure sensor 31. The metal case 350 is manufactured by drawing a thin metal plate having a thickness of 0.5 mm or less into a cylindrical shape, and is joined to the base 340 by brazing such as laser welding or copper brazing. .
In the pedestal 340 that is integrated with the metal case 350, the detent receiver 341 and the detent 317 of the nut 310 are accurately opposed to each other. Further, the inner diameter portion 342 of the pedestal 340 and the O-ring 343 made of silicon or fluororubber, which is fitted and arranged in a notch groove provided near the center of the small diameter portion 314 of the nut 310, are securely in close contact with each other. . The metal case 350 is fitted so as to be inscribed in the large-diameter portion 313 of the nut 310, and the inscribed portion 351 between the metal case 350 and the large-diameter portion 313 of the nut 310 is entirely joined by YAG laser welding. ing.
Thus, the pedestal 340 is shaped to be pressed against the surface of the engine head 1 by the axial force (screw tightening force) of the nut 310. The piezoelectric element portion 320, the electrode 331, and the insulator 332 are sandwiched and fixed between the nut 310 and the pedestal 340 by the axial force of the nut 310.
The method for assembling the combustion pressure sensor 31 is as follows. First, the signal extraction line 501 is welded to the hole 331 a of the electrode 331 on one end side of the lead wire 500. Further, the fixing bracket 333 is fitted into the fixing bracket holding hole 316a of the nut 310 and coupled by welding or brazing such as copper brazing. An insulator 332 is attached to the small diameter portion 314 of the nut 310.
An electrode 331 in which one end side of the lead wire 500 is connected while the other end side of the lead wire 500 is inserted into the hole 316 from the insulator 332 side to the nut 310 to which the fixing metal fitting 333 and the insulator 332 are attached, The nut 310 is fitted into the small diameter portion 314.
After the electrode 331 is disposed at a predetermined position, the fixing bracket 333 and the ground side shield wire 503 are simultaneously crimped and fixed. Thereafter, a part of the lead wire 500 and the fixing bracket 333 are covered with an insulating coating 333a to prevent dust and water. Thereby, the ground side shield wire 503 and the fixing bracket 333 are also electrically connected.
Next, the piezoelectric element portion 320 including the piezoelectric ceramic 321 and the both washer rings 322 and 323 is inserted into the small diameter portion 314 of the nut 310. Then, the pedestal 340 integrated with the metal case 350 by brazing or the like is inserted into the small diameter portion 314 of the nut 310, and the rotation receiver 317 and the rotation stopper 341 are made to coincide with each other. Then, the metal case 350 and the large-diameter portion 313 of the nut are laser-welded in a state where the base 340 and the nut 310 are pressurized so as to be in close contact with each other. Thus, the combustion pressure sensor 31 is completed.
Next, the combustion pressure sensor 31 is attached to the plug main body 220. Here, in the present embodiment, as described above, the plug body portion 220 has a unique configuration in which the outer diameter on the other end side including the hexagonal portion 221 is made smaller than the screw inner diameter 311a of the combustion pressure sensor 31. The plug main body 220 can be inserted into the through hole 31a of the combustion pressure sensor 31 from the other end side.
First, the plug main body 220 is inserted into the screw hole 1b from one end side (heating element 206 side) thereof. Then, the hexagonal portion 221 of the housing 201 is rotated around the axis by using a plug wrench 900 as shown in FIG. In the present embodiment, an air impact wrench can be used as the plug wrench 900. In this way, the mounting screw 201a of the plug main body 220 and the screw portion 1c of the screw hole 1b are screwed together, and the plug main body 220 is attached and fixed to the engine head 1.
Next, the combustion pressure sensor 31 is fitted from the other end side (the hexagonal portion 221 side) of the plug main body 220, and the nut 310 of the combustion pressure sensor 31 is attached by a socket wrench 910 or the like in the same manner as shown in FIG. The sensor 31 is pressed and fixed to the seat surface 1 e of the engine head 1 by tightening along the mounting screw 201 a of the plug main body 220. Thus, the combustion pressure sensor structure shown in FIG. 1 is completed.
Next, the operation of this embodiment will be described based on the above configuration. When starting the diesel engine, a voltage is applied to the plug body 220 from the power source (not shown) via the connecting bar, and grounded to the engine head 1 via the center shaft 224, the heating coil 203, the sheath tube 202, and the housing 201. The As a result, the heating element 206 generates heat and can assist ignition start of the diesel engine.
Then, after the engine is started, the combustion pressure generated in the engine is transmitted to the mounting screw 201a via the heating element 206 and the housing 201. Subsequently, the combustion pressure transmitted to the mounting screw 201 a relaxes the tightening torque to the engine head 1 in the glow plug 100. Accordingly, the load (load in the plug axis direction) applied to the piezoelectric ceramic 321 through the threaded portion 311 of the nut 310 in the combustion pressure sensor 31 is relaxed (that is, the load state applied to the piezoelectric ceramic 321). Changes).
Therefore, the generated charge of the electric signal output along the piezoelectric characteristics of the piezoelectric ceramic 321 changes. This electric signal (charge) is sent from the electrode 331 and the lead wire 500 to an external circuit via the connector 400, converted into a voltage, subjected to amplification, filtering, etc., and combustion control is performed as a combustion pressure waveform signal, for example. Applied to. The above is the entire detection mechanism of the combustion pressure in the glow plug 100.
By the way, according to the present embodiment, the combustion pressure sensor 31 can also be inserted from the end of the plug body 220 on the hexagonal part (nut part) 221 side, so the plug body (structure) 220 is inserted into the screw hole 1b of the engine. After the screw connection, the sensor 31 can be attached to the plug main body 220. Therefore, when the glow plug 100 is attached to the engine head (that is, the combustion pressure sensor structure is formed), it is not affected by the lead wiring 500 connected to the combustion pressure sensor 31 and the workability is improved. be able to.
That is, since the combustion pressure sensor 31, the lead wire 500, and the fixing bracket 333 are not present during the tightening operation of the plug main body 220, contact (interference) between these members and the plug wrench 900 is eliminated. Therefore, disconnection, deformation or breakage of these members due to contact with the plug wrench can be prevented. Further, conventionally, when an impact force is transmitted to the combustion pressure sensor due to the drop of the plug wrench 900, the internal piezoelectric element is damaged, which causes an obstacle to taking out the output signal. There is no such problem.
Therefore, in the present embodiment, as the plug wrench 900, an air impact wrench excellent in mounting workability that is used only with a general glow plug can be used without any problem. Thus, according to the combustion pressure sensor structure of the present embodiment, the mounting workability and the quality of the combustion pressure sensor 31 are ensured, and the work efficiency can be improved.
Furthermore, according to the present embodiment, the problem of erroneous mounting of the conventional glow plug with combustion pressure sensor J1 as shown in FIG. 4 can be solved. 4A is a cross-sectional view of the glow plug J1 alone shown in FIG. 14, and FIG. 4B is a cross-sectional view showing an erroneous mounting state of the glow plug J1.
In a state where the combustion pressure sensor 30 is temporarily attached to the mounting screw 201a of the plug main body 200, the length L2 from the housing lower end surface 201e to the lower end surface of the combustion pressure sensor 30 is tapered, for example, as shown in FIG. It is assumed that the screw hole 1b from the seat surface portion 1d to the seat surface 1e of the engine head 1 is mounted below the depth L1 (plug hole depth, see FIG. 4B). If the plug body 200 is continuously tightened in this state, the lower end surface of the combustion pressure sensor 30 comes into contact with the seat surface 1e of the engine head 1 before the contact between the housing taper portion 212 and the taper seat surface portion 1d. A gap S is generated as shown in FIG.
At this time, although the plug body 200 is tightened alone, the combustion pressure sensor 30 is pulled by the plug body 200 toward the combustion chamber 1a in the same axial direction. Therefore, as a result, the plug main body 200 is in a form in which the combustion pressure sensor 30 is kept in close contact with and pressed against the seating surface 1e of the engine head 1 until the standardized recommended tightening torque is reached.
Accordingly, although the housing taper portion 212 and the taper seat surface portion 1d are not necessarily in close contact / pressure contact with a standard axial load, relatively, in the pressure contact between the combustion pressure sensor 30 and the seat surface 1e of the engine head 1, The recommended tightening torque is reached. For this reason, there is a possibility that the attaching operator mistakenly recognizes that the plug main body 200 is normally attached to the engine head 1.
As a result, the combustion gas, that is, the combustion pressure leaks to the outside from the gap S shown in FIG. 4 (b), the performance of the combustion pressure sensor 30 is deteriorated due to the thermal effect, the engine output is decreased, the engine vibration is caused by the combustion fluctuation, Deterioration of acceleration and the like occur and give the driver discomfort. In this respect, according to the present embodiment, the combustion pressure sensor 31 can be attached to the plug main body 220 after the plug main body (structure) 220 is screwed to the screw hole 1b of the engine. The problem can be prevented.
Further, according to the present embodiment, the distance between the upper end surface of the nut 310 of the combustion pressure sensor 31 and the upper end surface of the hexagonal portion 221 of the plug main body 220 (without being held and fixed by other members of the plug main body 220). As a result of shortening the open portion) from about 60 mm to about 30 mm, for example, an effect on the detection of the combustion pressure appeared.
This is because the length effect due to the shortening is combined with the lightening effect due to the weight being reduced by about half by reducing the diameter of the plug body 220, reducing the mechanical vibration noise generated by the plug body 220 itself, This is because the mechanical vibration noise can be easily shifted to a high frequency that is not included in the combustion frequency of several Hz to 5 kHz required for combustion control by the combustion pressure sensor 31, for example.
The first embodiment has been described above. Here, a modified example of the present embodiment is shown as a schematic cross-sectional view in FIG. This modification is a combination of a separate nut 600 having a single screw function without forming a female thread portion in the through hole 32a of the annular combustion pressure sensor 32 as shown in the figure, and is exactly the same as the above example. An effect is obtained. Here, since the combustion pressure sensor (pressure sensor) 32 in this modification has a slightly different configuration from the combustion pressure sensor 31, the detailed configuration will be described with reference to FIG.
In the sensor 32, two piezoelectric ceramics 302 having an annular polarity made of lead titanate or lead zirconate titanate are arranged around the annular electrode 301 and electrically parallel to each other. Coupled to form a piezoelectric element portion. The electrode 301 and the piezoelectric ceramic 302 are packaged and protected so as to be sandwiched between a metal case 303 and a pedestal 304 each having a substantially annular shape.
Further, a protection tube 303b as a through hole is integrally formed on the large diameter portion 303a of the metal case 303 by welding, brazing, or the like. 305 of the lead wiring referred to in the present invention is inserted and supported. In the shielded electric wire 305 inserted into the metal case 303, the core wire 305 a is welded to the electrode 301 and connected. Further, the shield wire 305b insulated from the core wire 305a is connected to the metal case 303 which is also a body ground by being caulked with the protection tube 303b.
The combustion pressure sensor 32 is assembled as follows. First, a silicon heat-shrinkable insulating tube 306 is heated and brought into close contact with the circumferential side surface of the small-diameter portion 303c of the metal case 303, and the piezoelectric ceramic 302, the electrode 301, and the piezoelectric ceramic 302 are sequentially followed by the small diameter of the metal case 303. It fits into the part 303c. Here, the insulating tube 306 prevents an electrical short circuit between the piezoelectric ceramic 302 and the electrode 301 and the metal case 303.
Here, the electrode 301 fitted into the metal case 303 is in a state where the core wire 305a of the shielded electric wire 305 is welded and connected. The electrode 301 is fitted into the small diameter portion 303 c of the metal case 303 while feeding the end of the shielded electric wire 305 opposite to the connection side from the protection tube 303 b to the outside of the case 303.
Subsequently, a pedestal 304 fitted with an O-ring 309 is inserted into the metal case 303. Then, while pressing the metal case 303 and the pedestal 304 from above and below, the contact surfaces on the outermost periphery are joined by YAG laser welding (in FIG. 5, the welded portion is indicated by Y1). Thereby, in the combustion pressure sensor 32, integration can be achieved in a state where all the members are completely adhered and sealed.
Further, by caulking the shielded electric wire 305 and the protection tube 303b, electrical connection between the shielded wire 305b and the metal case 303, holding and fixing of the electric wire 305, and adhesion between the electric wire 305 and the tube 303b are ensured. . As a result, the metal case 303, the pedestal 304, and the shield wire 305b are electrically at the same potential. Thus, the combustion pressure sensor 32 of this modification is completed.
Then, the sensor 32 is fitted into the plug main body 220 after being mounted in the screw hole 1b from the other end side (hexagonal part 221 side), and the separate nut 600 is also fitted. The combustion pressure sensor 32 is supported and fixed on the surface of the engine head 1 by tightening the separate nut 600 along the mounting screw 201a of the housing 201. Thus, the mounting of the glow plug 100 with the combustion pressure sensor having the combustion pressure sensor 32 in the present modification to the engine head 1 is completed.
Thus, in this modification, the combustion pressure sensor 32 can be fixed to the plug body 220 by the axial force of the separate nut 600 screwed to the mounting screw 201a of the plug body 220. In this case, in addition to having the effects described above, it is not necessary to form a threaded portion in the through hole 32a of the combustion pressure sensor 32.
Further, the shielded electric wire (lead wiring) 305 is drawn out and connected to the combustion pressure sensor 32 from a direction different from the acting direction of the axial force of the separate nut 600, that is, from the circumferential side surface direction of the sensor 32. Thereby, interference with the separate nut 600 and the lead wiring 305 can be avoided efficiently.
In the second embodiment, in the glow plug with a combustion pressure sensor as the combustion pressure sensor structure, the lead wiring is configured to be detachable from the combustion pressure sensor. FIG. 6 is a partial vertical cross-sectional view showing an overall outline of the glow plug 110 with a combustion pressure sensor according to the present embodiment attached to the engine head 1 of a diesel engine. This glow plug 110 is obtained by changing the combustion pressure sensor 33 using the conventional plug main body 200 shown in FIG.
In the plug main body 200, it is unavoidable in terms of strength in consideration of the use environment conditions and the like, and it may be difficult to downsize the hexagonal portion 201b as in the first embodiment. In that case, the combustion pressure sensor is temporarily attached to the plug main body 200 and then attached to the engine head 1 as before. Even in such a case, the present embodiment realizes the object of the present invention.
A detailed cross section of the combustion pressure sensor (pressure sensor) 33 of the present embodiment is shown in FIG. The combustion pressure sensor 33 is different from the combustion pressure sensor 31 shown in FIG. 3 in the configuration of the lead portion that is a portion for electrically connecting the piezoelectric element portion 320 and one end side of the lead wire 500. Hereinafter, this difference will be mainly described, and the same parts are denoted by the same reference numerals as those in FIG. 3 in FIG.
As shown in FIG. 7, the lead portion of the combustion pressure sensor 33 is largely a sensor main body side lead portion 360 which is the piezoelectric element portion side so that the lead wire 500 can be attached to and detached from the combustion pressure sensor 33. And a metal connector 380 which is a lead wire side lead portion.
First, the sensor main body side lead part 360 will be described. In the holes 361 and 362 formed in the hexagonal portion 312 of the nut 310, a metallic signal extraction pin 364 that is insulatively coated with a two-stage cylindrical insulating pipe 363 made of fluororesin or the like is fitted and disposed. The tip of the pin 364 is exposed from the insulating pipe 363 and has a needle shape that can be fitted into the cylindrical crimp terminal 381 of the metal connector 380.
Further, a connector mounting screw 365 (female screw) that can be screwed with a male screw 382 formed on the metal connector 380 is formed around the exposed tip portion of the pin 364. The rear end portion of the signal extraction pin 364 is inserted into a hole 331a formed in the electrode 331 through a notch portion 332a formed in the insulator 332, and is welded and connected to the electrode 331.
Thus, the signal extraction pin 364 is sandwiched between the nut 310 and the pedestal 340 with the insulating pipe 363, the insulator 332, the piezoelectric ceramic 321, the signal extraction side washer ring 322, and the ground side washer ring 323 interposed therebetween. The insulating pipe 363, the signal extraction pin 364, and the connector mounting screw 365 constitute a sensor main body side lead portion 360.
On the other hand, the metal connector 380 basically includes a lead wire 500 having a laminated structure including a signal lead wire 501, an insulation coating 502, a ground shield wire 503, and an insulation coating 504, the male screw 382 and the hexagonal portion 383. And the above-mentioned cylindrical crimp terminal 381 provided in the fixing bracket 384. Here, the cylindrical crimp terminal 381 is insulated from the fixing metal fitting 384 by an insulating pipe 385 made of a fluororesin or the like, and is crimped and connected to the signal extraction line 501.
In addition, the lead wire 500 holds and fixes the insulation coating 504 and the ground side shield wire 503, which are a part of the lead wire 500, to the cylindrical portion of the fixing bracket 384 at the same time. With this crimping by caulking, the ground side shield wire 503 and the fixing metal 384 are electrically connected, and the insulating ring 386, the cylindrical crimping terminal 381 and the insulating pipe 385 disposed therein are fixed to the fixing metal 384. Thus, a metal connector 380 composed of the lead wire 500 and the fixing bracket 384 is formed.
In the lead portion of the sensor 33 constituted by the sensor main body side lead portion 360 and the metal connector 380, the signal extraction pin 364 is connected to the cylindrical crimping terminal 381 while the connector mounting screw 365 and the male screw 382 are screwed together. By fitting in a press-fitting manner, both can be electrically connected and held and fixed. As described above, the lead portion of the sensor 33 is configured to be screw-coupled so that the lead wire 500 can be easily detached from the combustion pressure sensor 33.
Therefore, the mounting procedure of the present embodiment is such that one end side (heating element 206 side) of the plug body 200 is inserted into the through hole 33a of the combustion pressure sensor 33 without the lead wire 500 and temporarily mounted, and then the plug body. The portion 200 is held and fixed to the engine head 1, and the combustion pressure sensor 33 is then fixed to the seat surface 1 e of the engine head 1, and then the metal connector 380 of the lead wire 500 is separately connected to the connector mounting screw 365 of the combustion pressure sensor 33. This is done by connecting to
Thus, according to the present embodiment, since the lead wiring 500 is detachable from the combustion pressure sensor 33, the lead wiring 500 is connected after the plug body portion (structure) 200 is screwed to the screw hole 1b of the engine. It can be retrofitted to the combustion pressure sensor 33. Therefore, when forming the combustion pressure sensor structure, workability can be improved without being affected by the lead wiring connected to the combustion pressure sensor.
Also, since the lead wire 500 and the connector 400 do not exist even when the combustion pressure sensor 33 itself is mounted, the lead wire 500 and the connector 400 (see FIG. 16) housed in the conventional socket wrench 910 and the plug main body 200. No entanglement or breakage of the lead wire 500 or the like. Therefore, as with the plug main body 200, as a result, an air impact wrench can be used for mounting the sensor 33, although not shown, and the workability and efficiency during mounting are improved.
Here, a modification of the second embodiment is shown in FIG. 8 and FIG. 9 as a schematic cross section. In the combustion pressure sensor 34 shown in FIG. 8, the sensor body side lead portion 360 electrically connected to the annular piezoelectric element portion 320 formed by sandwiching the electrode 331 between two piezoelectric ceramics 321 is arranged in the circumferential side surface direction. The metal connector 380 is attached perpendicularly to the axis of the plug body 200. The combustion pressure sensor 34 is also screw-coupled to the mounting screw 201a of the plug body 200 at the inner surface of the through hole 34a.
A combustion pressure sensor 35 shown in FIG. 9 is obtained by applying this embodiment to the combustion pressure sensor 32 shown in FIG. Also in this embodiment, the sensor 35 is not formed with a female thread portion, but is combined with a separate nut 600 having a single screw function, whereby the combustion pressure sensor 35 is screwed to the mounting screw 201a. You may fix to the plug main-body part 200 with the axial force of 600. FIG. This eliminates the need to form a threaded portion in the through hole 35a of the combustion pressure sensor 35.
In the second embodiment, the lead wiring 500 is screwed to the combustion pressure sensors 33 to 35 to realize the detachable configuration, but the detachable configuration of both is limited to the screw coupling. Anything, not something. For example, a protruding portion may be provided on one side, and a concave portion or a catching portion corresponding to the protruding portion may be provided on the other side, and both may be locked.
In this third embodiment, in a glow plug with a combustion pressure sensor as a combustion pressure sensor structure, a notch portion that is notched from the outer periphery toward the inside is formed in the combustion pressure sensor. The combustion pressure sensor is arranged so as to be fitted to the structure.
That is, the glow plug with a combustion pressure sensor of the present embodiment is obtained by changing the combustion pressure sensors 36 and 37 using the conventional plug main body 200 shown in FIG. 14, and as in the second embodiment, This is suitable when it is difficult to reduce the size of the hexagonal portion 201b of the plug body 200.
10, (a) is a top view (plan view) of a combustion pressure sensor (pressure sensor) 36 according to the present embodiment, and (b) is a cross-sectional view taken along line BB of (a). The present combustion pressure sensor 36 differs from the substantially annular combustion pressure sensor 32 shown in FIG. 5 in that its outer shape is deformed. Hereinafter, this difference will be mainly described and the same. In FIG. 10, the same reference numerals as those in FIG.
The combustion pressure sensor 36 of the present embodiment has a notch 36a that is cut in a U shape from the circumferential side surface toward the inside. Therefore, in this sensor 36, the electrode 301, the piezoelectric ceramic 302, the metal case 303, and the pedestal 304, which are annular in FIG. 5, are naturally cut out corresponding to the notch shape. The U-shaped curved portion of the notch 36 a has a shape such that its inner peripheral surface is in contact with the outer peripheral surface of the mounting screw 201 a of the plug main body 200.
The combustion pressure sensor 36 has a notch portion from the direction perpendicular to the axis of the plug body portion 200 with respect to the plug body portion 200 after the plug body portion 200 in which the separate nut 600 has been fitted in advance is attached to the screw hole 1b. After being arranged so as to be fitted from the opening side of 36a, the separate nut 600 is tightened along the mounting screw 201a of the plug main body 200, thereby being supported and fixed to the seat surface 1e of the engine head 1. Thus, the mounting of the glow plug with the combustion pressure sensor having the combustion pressure sensor 36 to the engine head 1 is completed.
As described above, according to the present embodiment as well, although it is necessary to attach the separate nut 600 to the plug main body 200 in advance, the combustion pressure sensor 36 is attached after the plug main body 200 is screwed to the engine head 1. Therefore, when forming the combustion pressure sensor structure, workability can be improved without being affected by the shielded electric wire (lead wiring) 305 connected to the combustion pressure sensor 36. Moreover, since the electric wire 305 is pulled out from the circumferential side surface direction of the sensor 36, interference between the separate nut 600 and the electric wire 305 can be efficiently avoided.
Here, as a modification of the present embodiment, a combustion pressure sensor 37 shown in FIG. 11 is obtained by applying the present embodiment to the combustion pressure sensor 35 shown in FIG. 11, (a) is a top view (plan view) of the combustion pressure sensor (pressure sensor) 37, and (b) is a cross-sectional view taken along the line CC of (a).
In this example, the plug main body 200 in which the separate nut 600 is fitted in advance is fixed to the engine head 1 and the combustion pressure sensor 37 is disposed so as to be fitted to the plug main body 200 from the opening side of the notch 37a. After tightening, the lead wire 500 can be connected to the sensor 37 via the metal connector 380.
Note that the notches 36a and 37a of the combustion pressure sensors 36 and 37 in the third embodiment are fitted to the plug body 200 from the opening side of the notch from the direction perpendicular to the axis of the plug body 200. Any shape can be used as long as it can be arranged so as to match, and the shape is not particularly limited.
In addition, the fixing of the combustion pressure sensors 36 and 37 of the present embodiment to the plug main body 200 is not limited to anything other than tightening with the separate nut 600, and anything may be used. For example, you may make it fix to the engine head 1 via a separate flange member.
The configuration described in the first embodiment, that is, the outer diameter of the other end side including the hexagonal portion 201b in the plug main body 220 is made smaller than the inner diameter of the through hole of the combustion pressure sensor, and the plug main body The configuration in which 220 can be inserted into the combustion pressure sensor from the other end side can also be applied to the configurations of the second and third embodiments (combustion pressure sensors 33 to 37). When the first embodiment and the third embodiment are combined, the notches 36a and 37a correspond to the through holes of the combustion pressure sensor.
In the above embodiment, a glow plug with a combustion pressure sensor has been described as an example of the combustion pressure sensor structure. However, the present invention is not limited to a glow plug with a combustion pressure sensor, but also for screw holes formed in an engine. A structure (for example, a bolt, a spark plug, an injector, etc.) that is screw-coupled by inserting one end side and rotating around the axis, and a combustion pressure sensor that is attached to the structure and detects the combustion pressure of the engine It can be applied to a combustion pressure sensor structure including the above, and the object of the present invention can be realized. An application example to the spark plug 700 is shown in FIG. 12, and an application example to the bolt 800 is shown in FIG.
In FIG. 12, a spark plug (structure as referred to in the present invention) 700 is attached to a screw hole 1b of an engine head 1 of a gasoline engine by a mounting screw (screw portion of the structure) 701a formed on the outer peripheral surface of a housing 701. It has been. Further, in FIG. 13, a bolt (structure in the present invention) 800 as a member exposed to the combustion chamber 1a in the engine head 1 is provided with an attachment screw (screw portion of the structure) 801a formed on the outer peripheral surface thereof. Is attached to the screw hole 1b of the engine head 1.
12 and 13, the combustion pressure sensor (pressure sensor) 31 is attached to the mounting screws 701a and 801a in the structures 700 and 800, and the force accompanying the combustion pressure acting on these structures. Is converted into an electrical signal based on the piezoelectric characteristics of the piezoelectric element 321 to detect the combustion pressure of the engine.
Also in the examples shown in FIGS. 12 and 13, the outer diameter of the hexagonal portions (the nut portions in the present invention) 701 b and 801 b of the structures 700 and 800 is larger than the inner diameter of the through hole 31 a of the combustion pressure sensor 31. Each structure 700, 800 can be inserted into the through hole 31a of the combustion pressure sensor 31 from the hexagonal end. Thereby, there exists an effect similar to the said 1st Embodiment. Also in these examples, it is needless to say that the second and third embodiments described above and other embodiments can be applied. Although not shown, the present invention is also applicable to an injector attached to an engine.
The nut portion of the present invention is not limited to the hexagonal portions 201b, 221, 701b, and 801b having a hexagonal shape, and the shaft portion is rotated to perform screw coupling with the screw hole 1b to the structure. Any shape such as a triangle, a quadrangle, an octagon, etc. may be used as long as it can give a rotational force to the.
FIG. 1 is an overall schematic cross-sectional view of a glow plug with a combustion pressure sensor according to a first embodiment of the present invention.
2A is a partial external view of the glow plug shown in FIG. 1, and FIG. 2B is a top view of the hexagonal portion of the housing in FIG.
FIG. 3 is a detailed explanatory diagram of the combustion pressure sensor in FIG. 1;
FIG. 4 is an explanatory view of erroneous mounting in a conventional glow plug with a combustion pressure sensor.
FIG. 5 is a schematic sectional view showing a combustion pressure sensor as a modification of the first embodiment.
FIG. 6 is an overall schematic cross-sectional view of a glow plug with a combustion pressure sensor according to a second embodiment of the present invention.
7 is a schematic cross-sectional view showing details of the combustion pressure sensor in FIG. 6. FIG.
FIG. 8 is a schematic cross-sectional view showing a combustion pressure sensor as a modification of the second embodiment.
FIG. 9 is a schematic sectional view showing a combustion pressure sensor as another modification of the second embodiment.
FIG. 10 is a detailed explanatory diagram of a combustion pressure sensor according to a third embodiment of the present invention.
FIG. 11 is a detailed explanatory view showing a combustion pressure sensor as a modification of the third embodiment.
FIG. 12 is a diagram showing an example in which the present invention is applied to a spark plug as a structure.
FIG. 13 is a diagram showing an example in which the present invention is applied to a bolt as a structure.
FIG. 14 is a view showing a general structure of a conventional glow plug with a combustion pressure sensor.
FIG. 15 is an explanatory view showing a method of mounting the plug body in the glow plug with a combustion pressure sensor.
FIG. 16 is an explanatory view showing a method for mounting a combustion pressure sensor in a glow plug with a combustion pressure sensor.
1b ... Screw hole of engine head, 31-37 ... Combustion pressure sensor,
31a-35a ... through hole of combustion pressure sensor, 36a, 37a ... notch,
200, 220 ... plug body, 201a ... mounting screw for the plug body,
221: Hexagonal portion of the plug body, 305 ... Shielded wire,
311 ... Combustion pressure sensor screw part, 500 ... Lead wire, 600 ... Separate nut,
700 ... Spark plug, 701a ... Spark plug mounting screw,
701b ... Hexagonal portion of spark plug, 800 ... bolt,
801a: bolt mounting screws, 801b: hexagonal bolts.
One end side is inserted into the screw hole (1b) formed in the engine and is screw-coupled, and the screw portion (201a, 701a, 801a) and the other end side for screw-coupling to the outer peripheral surface A structure (220, 700, 800) having a nut portion (221, 701b, 801b) for applying a rotational force around an axis to perform the screw connection to
Combustion pressure sensors (31-37) having through holes (31a-37a) into which the structure can be inserted and detecting the combustion pressure of the engine based on the force accompanying the combustion pressure acting on the structure When,
Lead wiring (305, 500) for taking out the signal of the combustion pressure sensor to the outside,
In the combustion pressure sensor structure in which the combustion pressure sensor is attached to the structure by inserting the structure into the through-hole formed in the combustion pressure sensor,
The outer diameter of the other end side including the nut portion in the structure is smaller than the inner diameter of the through hole of the combustion pressure sensor, and the combustion pressure sensor is inserted from the other end side of the structure. A combustion pressure sensor structure that can be inserted through a through hole.
A threaded portion (311) is formed on the inner surface of the through hole (31a, 33a, 34a) in the combustion pressure sensor (31, 33, 34), and the structure (220, 700, 800) passes through the through body. The combustion pressure sensor is fixed to the structure by inserting into the hole and screwing the screw part (201a, 701a, 801a) of the structure and the screw part of the through hole. The combustion pressure sensor structure according to claim 1, wherein:
A structure (200) having screw portions (201a, 701a, 801a) on the outer peripheral surface and screw-joined by inserting one end side into a screw hole (1b) formed in the engine and rotating it around an axis. 220, 700, 800),
A combustion pressure sensor (33-35, 37) that is attached to an intermediate portion in the axial direction of the structure and detects the combustion pressure of the engine based on the force accompanying the combustion pressure acting on the structure;
In the combustion pressure sensor structure comprising lead wires (305, 500) for taking out the signal of the combustion pressure sensor to the outside,
The combustion pressure sensors (33 to 35, 37) are formed with through holes (33a to 35a, 37a) having screw portions (311) on the inner surface,
By inserting the structure (200, 220, 700, 800) into the through hole and screwing the screw part (201a, 701a, 801a) of the structure and the screw part of the through hole, The combustion pressure sensor is fixed to the structure;
The combustion pressure sensor structure according to claim 1, wherein the lead wiring is detachable from the combustion pressure sensor.
The lead wire (305, 500) is screwed to the combustion pressure sensor (33-35, 37), and is detachable by this screw coupling. Combustion pressure sensor structure.
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