JPH0628672Y2 - Pressure detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention measures the internal pressure of a cylinder by taking out the output of a pressure sensor mounted on a mounting seat surface of an ignition plug screwed to a cylinder head by a lead wire. The present invention relates to a pressure detecting device.

[Conventional technology]

BACKGROUND ART Conventionally, in order to improve fuel efficiency and output of an internal combustion engine, it is common to control the internal combustion engine by measuring and feeding back the pressure in the cylinder. For that purpose, as shown in FIG. 9, the spark plug 2 is screwed into the cylinder head 1 by the screw 3, and the ring-shaped pressure sensor 5 is mounted on the mounting seat surface 4 thereof. A change in the pressure applied to the spark plug 2 in the cylinder results in a change in the pressure on the upper and lower surfaces of the pressure sensor 5, and the change in this pressure is taken out as a voltage by the lead wire 6 (for example, actual open Sho 62-65529).
No.).

As shown in FIG. 10, in the pressure sensor 5, the piezoelectric element 7 sandwiches the ring-shaped electrode 8, and the voltage induced in the ring-shaped electrode 8 by the piezoelectric element 7 is taken out by the lead wire 6. However, the piezoelectric element 7, the electrode plate 8 and the lead wire 6 are integrally fixed by the mold member 10, and the lead wire 6 is covered with the waterproof tube 11 and sealed with the sealant 12. In order to facilitate the mounting of the pressure sensor 5 on the seat surface 4 of the spark plug 2 and to improve the sealing performance against water, a cylindrical guide member 15 is provided on the outer periphery of the pressure sensor 5 as shown in FIG. And the pressure sensor 5 is fitted to the inner surface thereof. The guide member 15 is formed by deep-drawing and press-forming a metal plate, and is inserted into and supported by the spark plug insertion hole 14 formed in the cylinder head 1. At the portion where the pressure sensor 5 is fitted in the guide member 15, the lead wire 6
The guide member 15 is cut out where the pressure sensor 5 is projected for the reason that it does not come into contact with the portion where the lead wire 6 is taken out. The upper end 15a of the guide member 15 is bent outward,
A seal member 16 for sealing the spark plug insertion hole (hereinafter referred to as the seal member 16) is brought into close contact with the spark plug so as to cover the outer periphery, and the guide member 15 and the seal member 16 are integrally fitted into the spark plug insertion hole 14 of the cylinder head 1. is doing. A gasket 9 is interposed between the pressure sensor 5 and the spark plug 2. The lead wire 6 passes through the outer periphery of the guide member 15, and its extended end is taken out through the lead wire take-out hole 17 provided in the seal member 16 in an airtight manner. A vertical groove 18 is formed in a part of the spark plug insertion hole 14, and the lead wire 6
Can penetrate through the vertical groove 18, and in this portion, the circular sealing member 16 is bulged so as to cover the upper end of the vertical groove 18.

[Problems to be solved by the invention]

However, in such a conventional pressure detecting device, the pressure sensor 5 has a structure in which the mold member 10 is waterproof-sealed, and the connecting portion between the lead wire 6 and the electrode plate 8 is the waterproof tube 11 and the sealing material 12. And a spark plug insertion hole 14 is provided in the seal member 1.
6 has a structure in which the portion where the lead wire is communicated to the outside is sealed by the lead wire take-out hole 17 provided in the seal member 16, so that the structure is complicated and the cost is increased, and the sealing effect is also obtained. There was a problem that it also decreased.

The present invention has been made in view of such conventional problems, and an object thereof is to obtain a pressure detecting device capable of sealing with a simple structure.

[Means for solving problems]

In order to achieve this object, according to the present invention, the structure has a ring-shaped pressure which is interposed in the mounting seat surface (23) of the spark plug (20) screwed into the cylinder head (20). The output of the sensor (25) passes through a seal member (30) that seals the spark plug insertion hole (24) and leads (2).
6) In the pressure detecting device adapted to be taken out according to 6), the piezoelectric element (54) provided in the pressure sensor (25).
A holding plate (52) having a pressure receiving surface covering portion which is disposed on one of the pressure receiving surfaces and covers one pressure receiving surface, and a stretched standing portion which is extended upward when part of the pressure receiving surface is projected in the outer peripheral direction.
And a protruding portion (52a) for fixing the lead wire formed by protruding in a direction intersecting the extending direction on a part of the extending standing portion of the holding plate (52), and the outer circumference of the pressure sensor (25). The protruding portion (52a), a portion, a seal member portion that seals the spark plug insertion hole (24), and a lead wire covering portion that connects the seal member and the outer peripheral portion of the pressure sensor (25). The holding plate (52) to which the lead wire (26) is fixed is included, and a molding member (35) integrally molded is provided.

[Action]

Next, the operation of the present invention will be described. The lead wire fixing protrusion (52a) formed in a part of the extending standing portion of the holding plate (52) is bent in the direction close to the holding plate (52). The lead wire (26) and the holding plate (52) to which the lead wire (26) is fixed by the projecting portion (52a) so that the entire holding plate (52) is included, and the outer peripheral portion of the pressure sensor (25) and the spark plug are inserted. The seal member portion for sealing the hole (24) and the lead wire covering portion for connecting between the outer peripheral portion of the pressure sensor (25) and the seal member are integrally molded by the mold member (35). .

As a result, the lead wire (26) is firmly fixed and held, the connection between the pressure sensor (25) and the lead wire is firmly supported, and the lead wire (26) is applied with an external tensile force or the like. Also, the mold member (35) which tends not to be broken and tends to lack rigidity is reinforced, and the strength of the pressure detecting device is improved.

In addition, since it is integrally molded by the mold member, the number of parts is only one, resulting in a very simple structure, eliminating the trouble of installing things that were conventionally sealed separately by many parts. , Improve the mountability.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the present invention, in which a spark plug 21 is screwed into a cylinder head 20 with a screw 22, and a mounting seat surface 23 thereof is attached.
The ring-shaped pressure sensor 25 is inserted in the lead wire 2
6 shows a pressure detecting device for extracting pressure as voltage.
The pressure detecting device includes a plug boot 27 of the spark plug 21.
A seal member 30 (hereinafter referred to as a seal member) that seals the spark plug insertion hole 24 is provided below the flange 28 so as to abut against the flange 28. The outer peripheral portion of the pressure sensor 25 is molded by a molding member 31, and the pressure sensor 25 has an electrode plate 29, which includes the lead wire 26 and the electrode plate 2.
The connection portion with 9 is molded by the molding member 32. Therefore, the seal member 30, the mold member 31 on the outer periphery of the pressure sensor 25, and the lead wire 26.
And a portion of the molding member 32 at the connecting portion between the pressure sensor 25 and the electrode plate 29, and a portion of the member 34 for molding the lead wire 26 in the portion where the lead wire 26 reaches the through hole 33 provided in the seal member 30. Are molded integrally by providing a molding member 35 made of a plasticizer such as plastic or rubber. The plasticizer as the mold member 35 is used as the spark plug 2
Since the ambient temperature of 1 is high, a heat resistant material such as fluorine rubber or silicon rubber is preferable. Further, in order to prevent water from intruding from the joint surface between the mold member 35 and the metal surface of the cylinder head 20, it is preferable that the metal surface is previously treated with an adhesive or a primer to adhere it to the joint surface of the mold member 35. .

In the case of integrally molding, a mold as shown in FIG. 2 is used. The hole 40 into which the middle mold 42 is fitted in the lower mold 40
a is opened, and the middle die 42 is the disc spring 4 on the lower side.
1, a constant force is applied upward, and the disc spring 41 is supported by the retainer 43 below the disc spring 41.
The upper mold 44 is mounted so as to cover the upper surface of the middle mold 42 with the same center line as the center line 42a of the middle mold 42.
It becomes a space that creates 5. An upper space 45a of the space 45 serves as a mold for forming a part of the mold member 31 on the outer circumference of the pressure sensor 25, and a space 45b is a lead of a part from the lead wire 26 to the through hole 33 provided in the seal member 30. The mold forms a portion 34 for molding the wire 26, and the space 45c forms a mold for forming the seal member 30. A space 46 between the upper mold 44 and the lower mold 40 serves as a mold for a holding portion that fixes the lead wire 26.

In order to perform molding, the middle mold 42 is attached to the lower mold 40, the upper mold 44 is removed, the pressure sensor 25 is turned upside down on the upper part of the middle mold 42, and its center line 25a is set to the center line 42a of the middle mold 42. And lead wire 26 in space 4
Set it so that it comes to 5b. By mounting and pressurizing the upper mold 44, the middle mold 42 is fixed in a state in which the pressure sensor 25 is axially pressed with a constant pressure. Then, the molding agent is injected through the injection hole 47 provided at the boundary between the upper mold 44 and the lower mold 40 to perform molding.

FIG. 3 shows another embodiment. In this embodiment, a gasket 51 is built in the pressure sensor 50, and a stainless steel holding plate 52 is extended from the peripheral portion of the pressure sensor 50 along a shield wire 53 which is a sensor lead wire.
The shield wire 53 is fixed to the holding plate 52.
The pressure sensor 50 is housed in a stainless steel case 56, and has a piezoelectric element 54 and a lower surface electrode 55, and the lower surface electrode 55 is grounded to the engine of the cylinder head portion via the case 56. A center electrode 57 is attached to the upper surface of the piezoelectric element 54, and a part of the peripheral edge portion of the center electrode 57 extends and a part 53 of the center conductor 53 a of the shield wire 53.
It is spot-welded to b and 53c and becomes the output of the pressure sensor 50. An insulating plate 58 is attached to the upper surface of the center electrode 57 to insulate the holding plate 52 from the center electrode. Insulation plate 5
8 is a paper material such as glass, ceramics, or Kevlar impregnated with silicon resin, and the inner peripheral portion of the pressure sensor 50 of the insulating plate 58 is bent at a right angle to form a short cylindrical end portion 58a. The structure is such that 57 and the piezoelectric element 54 do not contact the case 56. Then, the whole is molded by the molding agent 59 to be integrated.

The holding plate 52 extends upward, and the shield wire 53 is fixed by caulking the protruding portion 52a. In this way, the molding agent 5 which tends to lack rigidity due to the holding plate 52 is used.
The gasket 51 having a structure that reinforces 9 and is difficult to retrofit can be attached to the pressure sensor 50.

FIG. 4 shows still another embodiment, in which the spark plug 61 is attached to the cylinder head 60 and the pressure sensor 62 is mounted in the same manner as in the embodiment of FIG. 1, but for sealing the spark plug insertion hole. When the part of the seal member 63 and the part of the lead wire 64 are integrally molded, the part that molds the pressure sensor 62 is not integrated, and the part of the seal member 63 for sealing the spark plug insertion hole and the lead wire Only a portion where a portion 65 surrounding 64 is extended to a connecting portion between the pressure sensor 62 and the lead wire 64 is integrally molded with a molding agent 66. FIG. 5 (a) is a cross-sectional view of the mold agent 66 taken out, showing the fifth section at the lower right.
A cross section 67 of the portion 65 surrounding the lead wire is shown in FIG.

FIG. 6 shows still another embodiment, which is substantially the same as the embodiment of FIG. 4, except that a holding plate 73 is attached to a portion 72 surrounding the lead wire 71 of the pressure sensor 70 to reinforce the molding agent. It is a thing. FIG. 7 (a) shows a cross-sectional view of the portion 75 of the molding agent taken out, and FIG. 7 (b) at the lower right thereof shows a cross-sectional view 76 of a portion surrounding the lead wire, which is a cross-section 76. There is formed a groove 74 into which the holding plate 73 is fitted, and this has a structure surrounding the connecting portion between the lead wire 71 and the pressure sensor 70. FIG. 8 shows a side view of the pressure sensor 70 and the holding plate 73 of the embodiment shown in FIG. 6 taken out. The holding plate 73 has a ring portion 73a to engage with the pressure sensor 70, and the clamp portion The lead wire 71 is crimped and fixed by 73b.

[Effect of device]

As described above, according to the present invention, the holding plate (5
The protruding portion (52a) for fixing the lead wire formed in a part of the extended standing portion of 2) is bent in the direction close to the holding plate (52) to fix the lead wire (26), and the protruding portion (52) is fixed. 5
2a) holding plate (5) to which lead wire (26) is fixed
2) The pressure sensor (25) so that the whole is included.
Of the pressure sensor (25) and the lead wire covering portion that connects the outer circumference of the pressure sensor (25) and the seal member. Since it is molded by the molding member (35), the lead wire (26) is firmly fixed and held, and the connection between the pressure sensor (25) and the lead wire can be firmly supported,
The lead wire (26) will not break even if external tensile force is applied, and the mold member (35), which tends to lack rigidity, can be reinforced and the strength of the pressure detection device can be improved. .

In addition, since it is integrally molded by the mold member, the number of parts is only one, resulting in a very simple structure, eliminating the trouble of installing things that were conventionally sealed separately by many parts. It is possible to improve the mountability.

Then, the seal structure of the pressure detecting device can be simplified, the manufacturing process can be reduced and the cost can be reduced, and
The reliability of the pressure sensor can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a sectional view showing a mold in the manufacturing process, and FIGS. 3 (a) and 3 (b) are sectional views of other embodiments. In the figure, (a) is a side sectional view, (b) is a vertical sectional view, FIG. 4 is a sectional view of yet another embodiment, and FIG. 5 (a) is a sectional view showing only the molding agent of FIG. FIG. 5 (b) is a partial cross-sectional view of FIG.
FIG. 6 is a sectional view of still another embodiment, FIG. 7 (a) is a sectional view showing only the molding agent of FIG. 6, and FIG. 7 (b) is a partial sectional view of FIG. Fig. 8 is a sectional view showing a part of Fig. 6, Fig. 9 is a sectional view of a conventional pressure sensor mounting structure, and Fig. 10 is a sectional view of a conventional pressure sensor and its lead wire lead-out portion. FIG. 11 is a cross-sectional view showing the assembly of a conventional pressure sensor and the seal structure of its lead wire portion. 20 ...... Cylinder head 21 ...... Ignition plug 23 ...... Ignition plug seating surface 24 ...... Ignition plug insertion hole 25 ...... Pressure sensor 30 ...... Ignition plug insertion hole sealing member 34 ...... Lead wire molded part 35 ...... Integral molding agent 52 ... Holding plate 52a ... Projection

Claims (1)

[Scope of utility model registration request] 1. A spark plug insertion hole (24) for outputting the output of a ring-shaped pressure sensor (25) interposed on a mounting seat surface (23) of a spark plug (20) screwed to a cylinder head (20). Lead wire (2) penetrating the seal member (30) for sealing the
6) In the pressure detecting device adapted to be taken out according to 6), the piezoelectric element (54) provided in the pressure sensor (25).
Of the pressure receiving surface, which is disposed on one of the pressure receiving surfaces and covers one pressure receiving surface, and a stretched standing portion which is formed by protruding a part of the pressure receiving surface in the outer peripheral direction and extending upward.
2), a protruding portion (52a) for fixing the lead wire formed by protruding in a direction intersecting the extending direction in a part of the extending standing portion of the holding plate (52), and the pressure sensor (25). The outer peripheral portion, a seal member portion that seals the spark plug insertion hole (24), and a lead wire covering portion that connects the seal member and the outer peripheral portion of the pressure sensor (25) to the protrusion ( 52a) and a holding member (52) to which the lead wire (26) is fixed, and a molding member (35) integrally molded, are provided.