JP4921309B2 - Engine pressure sensor - Google Patents

Description

  The present invention relates to an engine pressure sensor that detects a pressure in a cylinder of an engine.

  A sensor part that is installed at the bottom of a vertical hole-shaped plug hole formed in the cylinder head and inserts the mounting screw part of the engine plug into the center through-hole, and the conductivity that rises from the sensor part toward the opening part of the plug hole For example, Patent Document 1 discloses an engine pressure sensor having a sexual pipe portion and an output line connected to the sensor portion.

The pipe part of the engine pressure sensor has a double structure in which the outer side of the inner pipe is surrounded by an outer pipe. The output line is inserted into the gap between the inner pipe and the outer pipe, and a filler is inserted into the gap. Filled. In addition, an output line is drawn out from the gap between the inner pipe and the outer pipe, and a connector is attached to the end of the output line.
Japanese Patent No. 3226374

  The conventional engine pressure sensor has a double pipe structure, so that the degree of difficulty in processing is high and it is difficult to cope with extremely deep plug holes. Moreover, since it is necessary to fill the entire gap between the pipe portions having a double structure, there is a problem that the filling amount of the filler is large, which is uneconomical and heavy.

  The present invention has been made in view of the above problems, and an object thereof is to provide an engine pressure sensor that can easily cope with an extremely deep plug hole, can reduce weight, and can reduce wasteful cost. There is.

As described in claim 1, an annular sensor portion that is installed at the bottom of the plug hole and that inserts the mounting screw portion of the engine plug into the central through hole;
A pipe portion having a single structure extending elongated from the sensor portion toward the opening of the plug hole in a state of being installed in the plug hole;
An output line connected to the sensor unit;
An output line cover formed by projecting strip-like mounting pieces on both sides from the upper end to the lower end of the cover main body, one of which is a concave pipe in the form of a half pipe that extends from the lower part to the upper part of the pipe part , Have
The mounting piece of the output line cover is fixed to the outer peripheral surface of the pipe portion to form a wiring space from the lower portion to the upper portion of the pipe portion between the outer peripheral surface and the concave surface of the output line cover. There is provided an engine pressure sensor in which a filling material is filled and solidified in a state where the output line is passed through a wiring space, and the output line passed through the wiring space is fixed.

In addition, as described in claim 2, the two attachment pieces of the output line cover are spot-welded to the outer peripheral surface of the pipe portion , and are fixed at a plurality of positions at intervals in the axial direction of the pipe portion , and the axis line 2. The engine pressure sensor according to claim 1, wherein a space between welding spots arranged in a direction is a non-fixed portion, and air bleeding is performed from the non-fixed portion when filling the wiring space with the filler. To do.

  According to a third aspect of the present invention, a filling port for filling the wiring space with the filler is connected to the welding spots of the left and right mounting pieces which are the cover main body and sandwich the cover main body. The pressure sensor for an engine according to claim 2 provided on a line.

  The engine pressure sensor according to the present invention has a simple pipe part shape and is difficult to process. Therefore, it can be easily processed to be elongated, and therefore, it can easily cope with extremely deep plug holes. In addition, since the filler is filled in the wiring space formed between the outer peripheral surface of the pipe portion and the concave surface of the output line cover, the amount of filling of the filler can be reduced, so that the cost can be reduced accordingly. In addition, it is effective in reducing weight.

  The pressure sensor for an engine according to claim 2 is provided when the mounting piece of the output line cover is fixed to the outer peripheral surface of the pipe by spot welding, and the filler is filled from the non-fixed portion between the welding spots. Since air venting is performed, filling of the filler becomes very simple, and no special processing for air venting is required, so that productivity can be improved and costs can be reduced.

  According to a third aspect of the present invention, there is provided the engine pressure sensor according to the first aspect of the present invention, wherein the filling port for filling the wiring space with the filler is on the line connecting the welding spots of the left and right mounting pieces that are the cover main body and sandwich the cover main body. Therefore, there is no possibility that the filler leaks from the edge of the mounting piece even when the pressure when filling the filler with the filler is high.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of the engine pressure sensor, FIG. 2 is a longitudinal sectional view showing an enlarged state with the middle of the engine pressure sensor omitted, and FIG. 3 is a sectional view taken along line XX in FIG. 4 is a top perspective view of the pressure sensor for an engine showing a state in which the annular cap portion is divided at the center, FIG. 5A is a plan view of the noise shielding plate, FIG. 5B is a side view of the noise shielding plate, and FIG. (C) is a central longitudinal sectional view of the noise shielding plate, FIG. 6 is a plan view of the noise shielding plate showing another embodiment, and FIG. 7 is a sectional view of the main part of the engine showing the use state.

  An engine pressure sensor (hereinafter simply referred to as “pressure sensor”) 1 according to the present invention includes a sensor unit 2 located at the bottom of FIG. 1, an output line 3 connected to the sensor unit 2, and the sensor unit. A vertical hole-shaped plug formed in the cylinder head 6 of the engine as shown in FIG. 7, schematically comprising a pipe portion 4 raised from 2 and an annular cap portion 5 provided on the top of the pipe portion 4. Installed in Hall 7.

[Sensor part]
As shown in FIG. 2, the sensor unit 2 is a cup-shaped unit having a through hole 2 a at the center, and a metal inner cup 2 b located inside, and a metal outer cup 2 c located outside. The pressure detecting member 2d is a space between the outer cup 2c and the inner cup 2b and disposed around the through hole 2a.

  The space between the inner cup 2b and the outer cup 2c of the sensor unit 2 is filled with a filler 8 such as rubber without a gap, and the filler 8 is solidified in a state where the pressure detecting member 2d is sealed.

  On the other hand, the pressure detection member 2d is an integrated body such as a piezoelectric element, and electrically detects a change in pressure in the cylinder 9. Such a pressure detection member 2d is a known member that is also used in Patent Document 1, and thus detailed description thereof is omitted.

  A core wire 3a (described later) of the output line 3 is connected to the pressure detection member 2d of the sensor unit 2, and the output line 3 is also embedded in the filler 8. In the following description, the lead-out side (left side in FIG. 1) of the output line 3 is defined as the front side of the pressure sensor 1, and the opposite side (right side in FIG. 1) is defined as the rear side.

[Output line]
The output line 3 is a so-called lead wire, and the core wire 3a which is a conductor is covered with a covering cover 3b which is an insulator. One end (lower end) of the output line 3 is connected to the pressure detection member 2d of the sensor unit 2 as described above, and the other end (upper end) is omitted in side view as shown in FIGS. It is connected to the terminal metal fitting 10 which is an inverted L-shape and has a tip-shaped portion 10a.

[Pipe part]
The pipe part 4 is obtained by drawing a conductive metal tube, and as shown in FIGS. 1 and 2, the pipe part 4 has an outward flange part 4a at the top, and is a position slightly lowered from the flange part 4a. A stepped pipe is provided with a reduced diameter step portion 4b, and the lower end thereof is externally fitted to the inner cup 2b of the sensor portion 2 and welded.

[Pipe-Noise shielding plate]
On the upper surface of the flange portion 4a of the pipe portion 4, a noise shielding plate 4c made of a conductive metal plate is welded. The noise shielding plate 4c is formed in a disc shape along a circle C having the center axis O of the pipe portion 4 as the center O as shown by an imaginary line in FIG. The noise shielding plate 4c according to the embodiment has a substantially oval shape in which two substantially semicircles HCf and HCr are connected by straight lines L and L, and the rear side of the substantially oval shape. A circular hole 4e corresponding to the flange portion 4a is formed concentrically with the semicircle HCr, and the circumference of the circular hole 4e is welded to the upper surface of the flange portion 4a of the pipe portion 4. On the other hand, the semicircle HCf of the front portion 4d of the noise shielding plate 4c in the embodiment is an approximate semicircle, and as shown in FIG. Both ends of a circular arc A having a center angle of ± α with respect to the radius R toward the front end side of the metal fitting 10 are chamfered in an arc shape and connected to the straight lines L and L.

  As a result of repeated trials and trials, it was confirmed that when α exceeds 45 °, the noise shielding effect becomes almost constant, and as it becomes smaller, the noise shielding effect decreases. Therefore, if the α of the noise shielding plate 4c is set to 45 ° or more, a stable noise shielding effect can be obtained. Of course, depending on the use environment, there is of course a case where the noise shielding plate 4c having α of less than 45 ° can be used.

As described above, the noise shielding plate 4c of the embodiment is obtained by removing a part of the region other than the region covering the top of the terminal fitting 10 on the basis of the circle C having the center axis O of the pipe portion 4 as the center O. In other words, the region covering the top of the terminal fitting 10 and the region for joining the pipe portion 4 (around the circular hole 4e) are removed, and the good noise shielding performance is maintained while doing so. The weight can be reduced, and the fluidity of the resin at the time of insert molding is improved, so that the yield is improved.
Further, as shown in FIG. 6, the noise shielding plate 4c is formed in the shape of an imaginary line in FIG. 5A, and the holes 4f, 4f,. The same effect as described above can be obtained also when a means for removing a part by drilling is provided.

[Pipe part-Output line cover]
An output line cover 11 for passing the output line 3 is attached in front of the pipe outer peripheral surface 4g of the pipe portion 4. This output line cover 11 includes a cover main body 11a in the form of a half pipe (in which the pipe is divided into two in the axial direction), and strip-shaped attachment pieces 11b and 11b that project from both sides of the cover main body 11a. It is made to contact the front surface of the pipe outer peripheral surface 4g of the pipe portion 4 with the concave surface 11c of the cover main body 11a facing, and the attachment pieces 11b and 11b are fixed to the pipe outer peripheral surface 4g of the pipe portion 4 by spot welding. Do it. The welding spots Wa to We of the mounting pieces 11b and 11b are, as shown by arrows in FIG. 1, the upper and lower ends, the central portion, and a total of five points between them, and the space between the welding spots Wa to We is between them. It is a non-fixed part. The non-fixed portion is merely not fixed, and is in close contact with the pipe outer peripheral surface 4g with almost no gap.

  Between the concave surface 11 c of the output line cover 11 and the pipe outer peripheral surface 4 g of the pipe portion 4, a wiring space S having a bowl shape as shown in FIG. 3 is formed. The output line 3 is passed, and the output line 3 is firmly fixed by a filler 8 such as rubber filled in the wiring space S.

  The wiring space S is filled with the filler 8 from the filling port 11 d opened in the cover main body 11 a of the output line cover 11. In FIG. 1, two filling ports 11d are provided on the line connecting the welding spots Wb, Wb of the attachment pieces 11b, 11b on both sides and on the line connecting the welding spots Wd, Wd. Even if the pressure at the time of filling the filler 8 into the opening 11d is high, there is no possibility that the filler 8 leaks from the edges of the mounting pieces 11b and 11b. On the other hand, for filling the filler 8, it is indispensable to discharge the air in the wiring space S. As described above, the mounting pieces 11b and 11b of the output line cover 11 have a space between the welding spots Wa to We. Since it is left as a non-fixed part, air can be vented from there.

[Annular cap part]
The annular cap portion 5 is a synthetic resin molded product provided on the top of the pipe portion 4, and the terminal fitting 10 is disposed below the noise shielding plate 4 c, and the pin-shaped portion 10 a of the terminal fitting 10 is provided. And an intermediate portion other than the lower end portion and the noise shielding plate 4c are formed by insert molding. In the embodiment, the lower end portion of the terminal fitting 10 is covered with the same rubber 12 as the filler 8.

  As shown in FIG. 2, the annular cap portion 5 includes a neck portion 5a that covers the diameter-reduced step portion 4b of the pipe portion 4 from the bottom, an annular main portion 5b that surrounds the noise shielding plate 4c, and the annular main portion. A cylindrical base portion 5c protruding from the upper surface of the portion 5b and having the same central axis as the central axis of the pipe portion 4, and a pin shape of the terminal fitting 10 protruding forward from the peripheral side surface of the annular main portion 5b. And a cylindrical connector portion 5d surrounding the portion 10a.

  The noise shielding plate 4c is at a substantially intermediate position in height (thickness) with respect to the annular main body 5b. On the other hand, since the terminal fitting 10 is disposed under the front portion 4d of the noise shielding plate 4c, if the noise shielding plate 4c is flat, the terminal fitting 10 is provided in the lower half of the annular main body 5b. The upper half of the main body 5b has a thick resin layer. In such a state, when molten resin is injected and insert molding is performed, there is a possibility that the flow of the resin may stagnate in the lower half of the annular main body portion 5b, or pressure may not be applied evenly. There is a possibility that the front portion 4d of the shielding plate 4c is deformed.

  On the other hand, in the embodiment, as shown in FIG. 4, a curved portion 4 h that rises upward is formed in the center of the front portion 4 d of the noise shielding plate 4 c, and the distance between the curved portion 4 h and the terminal fitting 10 is The resin thickness of the annular main portion 5b above the curved portion 4h and below the terminal fitting 10 is set to be substantially the same (see FIG. 2). By doing so, the flow of the resin at the time of insert molding in front of the annular main body 5b is distributed almost evenly above the bending portion 4h, between the bending portion 4h and the terminal fitting 10, and below the terminal fitting 10. Partial resin stagnation and pressure imbalance are unlikely to occur, and as a result, deformation of the noise shielding plate 4c can be prevented and molding stability is increased.

  The gate position at the time of insert molding of the annular cap portion 5 is set after the annular main portion 5b on the opposite side of the terminal fitting 10, that is, the annular main portion 5b, and molten resin is injected from the gate. The gate is provided at the center of the annular main body 5b and set so that the molten resin is injected toward the noise shielding plate 4c, or two gates are provided above and below the noise shielding plate 4c. It is good to make it.

[Others]
In the figure, reference numeral 13 denotes an elastic seal ring fitted to the neck portion 5 a of the annular cap portion 5 and prevents water from entering the plug hole 7. Reference numeral 5e denotes an anchor projection protruding from the outer surface of the connector portion 5d of the annular cap portion 5 and engages with a hook portion 14a of another connector 14 inserted into the connector portion 5d to prevent the connector 14 from coming off. . Reference numeral 4 i denotes an air vent hole provided on the rear surface of the pipe portion 4.

[How to install pressure sensor]
First, as shown in FIG. 7, the pressure sensor 1 of the present invention is inserted into the plug hole 7 and the sensor unit 2 is placed on the bottom of the plug hole 7. In this state, the mounting screw portion 15a of the spark plug 15 that is an engine plug is inserted into the through hole 2a of the sensor portion 2, and the mounting screw portion 15a of the spark plug 15 is screwed into the female screw 6a of the cylinder head 6 and tightened. The sensor unit 2 is fastened to the bottom of the plug hole 7 with a force in a washer state.

  Next, the ignition coil 16 is installed on the cylindrical base part 5 c of the annular cap part 5. A plug cap 16 a is integrally suspended from the lower surface of the ignition coil 16, and the plug cap 16 a passes through the pipe portion 4 of the pressure sensor 1 and fits on the top of the ignition plug 15. Thereby, the ignition coil 16 and the spark plug 15 are electrically connected through the plug cap 16a.

  On the other hand, a connector 14 connected to a control device (not shown) is inserted into the connector portion 5d of the annular cap portion 5. Thereby, a control apparatus and the sensor part 2 are electrically connected.

  When the engine is operated in the above state, the change in the internal pressure in the cylinder 9 is detected by the sensor unit 2 of the pressure sensor 1, and the signal is transmitted to the control device, so that the combustion in the cylinder 9 is optimal. It is controlled to become.

  On the other hand, while the engine is operating, the engine vibrates and electromagnetic noise is generated from the ignition coil 16. In general, when the output line 3 of the pressure sensor 1 vibrates with the vibration of the engine, vibration noise is generated and superimposed on the sensor output, which may adversely affect the combustion control. Further, the electromagnetic noise of the ignition coil 16 is superimposed on the sensor output through the terminal fitting 10 provided in the annular cap portion 5, which may also adversely affect the combustion control.

On the other hand, the pressure sensor 1 according to the present invention is fixed to the wiring space S formed between the pipe outer peripheral surface 4g of the pipe portion 4 and the concave surface 11c of the output line cover 11 with the filler 8 through the output line 3, so that the engine Vibration noise associated with the vibrations of the
Further, in the pressure sensor 1 of the present invention, since the noise shielding plate 4c is disposed above the terminal fitting 10, electromagnetic noise is transmitted to the terminal fitting 10 even if there is a noise source such as the ignition coil 16 above the annular cap portion 5. Absent.

  The embodiments of the present invention have been described above, but the present invention is of course not limited to the above embodiments. For example, in the embodiment, the noise shielding plate is formed separately from the flange portion 4a and welded. However, the flange portion 4a itself can be enlarged to be a noise shielding plate integrated with the pipe portion 4. .

[Other technical ideas included in the above embodiment]
The above embodiment includes technical ideas such as the following items [A] to [G] for solving the following other problems existing in the conventional engine pressure sensor. ing.
That is, since the conventional engine pressure sensor has a connector attached to the tip of the output line drawn out to the outside, after the vehicle body is assembled, there is a fixing means for fixing the output line so that the output line does not fluctuate due to vibration. There is a problem that it is necessary to separately provide in the vicinity of the plug hole, and there is always a concern about disconnection of the output line drawn to the outside.

[A]
An annular sensor part that is installed at the bottom of the plug hole and passes through the mounting screw part of the engine plug through the central through hole;
A pipe portion extending from the sensor portion toward the opening of the plug hole in a state of being installed in the plug hole;
A flange-shaped noise shielding plate provided on the top of the pipe portion;
An output line connected to the sensor unit;
A terminal fitting which is connected to the output line and whose end is a pin-shaped portion;
The terminal metal fitting is arranged on the sensor part side of the noise shielding plate, and a resin-made annular cap portion is formed by insert molding in a state of including a part of the terminal metal fitting and the noise shielding plate. A pressure sensor for an engine, wherein a cylindrical connector portion surrounding the pin-shaped portion of the terminal fitting is formed integrally with the annular cap portion.

[B]
The annular cap portion includes a portion surrounding the noise shielding plate as an annular main portion, and the annular main portion includes a part of the terminal fitting, and further, a vertical space is provided between the noise shielding plate and the terminal fitting. The pressure sensor for an engine according to [A], wherein the resin thickness of the annular main portion above the noise shielding plate and below the terminal fitting is set to be substantially the same as the interval.

[C]
The noise shielding plate is disposed at a substantially middle position of the annular main portion of the annular cap, while a curved portion is formed in a portion corresponding to the terminal fitting of the noise shielding plate, and the curved portion and the [B], wherein the interval between the terminal fittings and the resin thickness of the annular main portion on the sensor portion side of the curved portion opposite to the sensor portion and the terminal fitting are set to be substantially the same. Engine pressure sensor.

[D]
With respect to the portion of the noise shielding plate that protrudes from the periphery of the pipe portion, the region other than the region that covers the opposite side of the terminal fitting from the sensor portion with reference to a circle centered on the central axis of the pipe portion. The engine pressure sensor according to any one of [A] to [C], wherein a part of the pressure sensor is removed.

[E]
The engine pressure sensor according to [D], wherein a region of the noise shielding plate that covers a side opposite to the sensor portion of the terminal metal fitting is the terminal metal fitting with respect to an entire circumference of 360 degrees. Surrounded by both ends of a fan-shaped arc centered on an angle of ± 45 ° with respect to the radius toward the pin-shaped portion side, and a straight line parallel to the radius and passing through both ends of the fan-shaped arc An engine pressure sensor characterized by being in a specified range.

[F]
The pressure sensor for an engine according to [D] or [E], wherein the noise shielding plate has a through hole in a region other than a region covering the side opposite to the sensor portion of the terminal fitting. A pressure sensor for an engine, wherein a part of the pressure sensor is removed.

[G]
The engine for the engine according to any one of [A] to [F], wherein a gate position at the time of insert molding of the annular cap portion is set to the annular main body portion on the opposite side of the terminal fitting. Pressure sensor.

It is a longitudinal cross-sectional view of the pressure sensor for engines. It is a longitudinal cross-sectional view which shows the state which abbreviate | omitted the middle of the pressure sensor for engines, and expanded. It is the XX sectional view taken on the line of FIG. It is a top perspective view of the pressure sensor for engines which shows the state where the annular cap part was divided in the center. (A) is a top view of a noise shielding board, (b) is a side view of a noise shielding board, (c) is a center longitudinal cross-sectional view of a noise shielding board. It is a top view of the noise shielding board which shows another form. It is principal part sectional drawing of the engine which shows a use condition.

DESCRIPTION OF SYMBOLS 1 ... Engine pressure sensor 2 ... Sensor part 2a ... Through-hole 3 ... Output line 4 ... Pipe part 4g ... Pipe outer peripheral surface 7 ... Plug hole 8 ... Filler 11 ... Output line cover 11a ... Cover main body 11b ... Attachment piece 11c ... Concave surface 11d ... Filling port 15 ... Spark plug (engine plug)
15a ... Mounting screw part S ... Wiring space Wa-We ... Welding spot

Claims (3)

An annular sensor part that is installed at the bottom of the plug hole and passes through the mounting screw part of the engine plug through the central through hole;
A pipe portion having a single structure extending elongated from the sensor portion toward the opening of the plug hole in a state of being installed in the plug hole;
An output line connected to the sensor unit;
An output line cover formed by projecting strip-like mounting pieces on both sides from the upper end to the lower end of the cover main body, one of which is a concave pipe in the form of a half pipe that extends from the lower part to the upper part of the pipe part , Have
The mounting piece of the output line cover is fixed to the outer peripheral surface of the pipe portion to form a wiring space from the lower portion to the upper portion of the pipe portion between the outer peripheral surface and the concave surface of the output line cover. A pressure sensor for an engine, wherein a filling material is filled and solidified in a state where the output line is passed through the wiring space, and the output line passed through the wiring space is fixed. Both mounting pieces of the output line cover are spot-welded to the outer peripheral surface of the pipe portion , and are fixed at a plurality of positions at intervals in the axial direction of the pipe portion , and are not fixed between welding spots arranged in the axial direction. 2. The engine pressure sensor according to claim 1, wherein an air bleeding when filling the wiring space with the filler is performed from the non-fixed portion.   The filling port for filling the wiring space with a filler is provided on a line connecting the welding spots of the left and right attachment pieces that are the cover main body and sandwich the cover main body. 2. The pressure sensor for an engine according to 2.

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