JP2867773B2 - Knock sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock sensor used as a vibration pickup in a knock control system for determining the presence or absence of knocking of an engine and controlling ignition timing to improve fuel efficiency.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional knock sensor. Hereinafter, the configuration of this conventional example will be described. In FIG. 7, 101 is a base block part, and 102 is a connector block part. First, the configuration of the base block unit 101 will be described. Reference numeral 103 denotes a base on which a projection 104 is formed at the center, and the outer peripheral surface of the base 103 has six surfaces like bolts. Reference numeral 105 denotes a screw portion formed integrally with the lower portion of the base 3, and the screw portion 105 is screwed into a screw hole provided in the engine. Reference numeral 106 denotes a hole formed at the center of the projection 104, and a sleeve 107 made of an insulating material is inserted into the hole 106. Reference numeral 108 denotes a metallic diaphragm, which has a projection 108a and a hole 108b formed in the center as shown in FIG. The diaphragm 108 is fixed to the projection 104 of the base 103 by welding. Reference numeral 109 denotes a piezoelectric ceramic bonded to the upper surface of the vibration plate 108, and a silver electrode 110 is provided on the upper surface of the piezoelectric ceramic 109. 111 is the base 1
An O-ring inserted into an annular groove formed in the opening of No. 03.

Next, the configuration of the connector block 102 will be described. Reference numeral 112 denotes a connector unit made of an insulator, and a terminal 113 is fixed inside the connector unit 112. Reference numeral 114 denotes a metal ring fixed to the outer periphery of the large diameter portion of the connector unit 112. Reference numeral 115 denotes a connector for extracting an electric signal from the terminal 113 to the outside. Reference numeral 116 denotes a sealant filled in the base 107 where the terminal 113 projects below the connector unit 112 and the sleeve 107 of the base block 101. 117 is terminal 113
And a lead wire 118 is soldered. The other end of the lead wire 118 is connected to the silver electrode 110 of the piezoelectric ceramic 109.

Next, a procedure for assembling a conventional knock sensor will be described. After assembling the base block 101 and the connector block 102 separately, the lead wire 1
18 is soldered to the lead 117 of the terminal 113 and the other end of the lead wire 118 is connected to the piezoelectric ceramic 10.
9 is soldered to the silver electrode 110. Thereafter, as shown in FIG. 7, the lead portion 117 is inserted into the sealant 116 filled in the sleeve 107, and the lower surface of the connector block portion 102 is sandwiched by the O-ring 111 and the upper surface of the base block portion 101. In this state, the ring 114 and the base 103 are integrated by full-length ring projection welding to complete the process.

[0005]

However, in the above-mentioned conventional knock sensor, the lead portion 1 of the terminal 113 is not provided.
17 and the piezoelectric ceramic 109 are connected to each other by soldering with lead wires 118, so that there is a problem that the variation in the amount of solder affects the characteristics of the knock sensor. Further, silver is applied to the piezoelectric ceramic 109 for soldering. At the time of soldering, a connection failure occurs due to a phenomenon of silver erosion, and at the same time, a difference in expansion coefficient between the solder and the piezoelectric ceramic 109 causes the soldering. There has been a problem that thermal stress occurs on the attachment surface and cracks occur on the soldering surface.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an excellent knock sensor capable of securely connecting a terminal to a piezoelectric ceramic without using solder. Is what you do.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a piezoelectric ceramic on one side with a metallic package.
Bonding the de, one end of the metallic pad and the lead wires are connected by spot welding, and further, in which the other end of the fixed terminal and the lead wire in the connector units to be connected by spot welding .

[0008]

The present invention is constructed as described above, and the connection between the piezoelectric ceramic and the lead wire and the connection between the terminal and the lead wire are spot-welded instead of solder, so that the difference in expansion coefficient between the solder and the piezoelectric ceramic is obtained. This prevents cracks from being generated on the soldered surface due to thermal stress caused by the soldering, and solves the problem of poor connection due to solder erosion of the silver electrode of the piezoelectric ceramic.

[0009]

1 to 6 show an embodiment of the present invention.
It is explained together with. FIG. 1 shows a completed state assembled together. FIG. 2 shows a state in which the base block 1 and the connector block 2 are disassembled. 1 and 2, reference numeral 3 denotes a base on which a projection 4 is formed at the center,
The outer peripheral surface of the base 3 has six surfaces like bolts. 5
Is a screw part formed integrally with the lower part of the base 3, and this screw part 5 is screwed into a screw hole provided in the engine. Reference numeral 6 denotes a hole formed at the center of the projection 4, and a sleeve 7 made of an insulating material is inserted into the hole 6. Numeral 8 denotes a metallic diaphragm, as shown in FIG. 3, having a narrowed portion 8a at the outer periphery and a hole 8b at the center. The diaphragm 8 is fixed to the projection 4 of the base 3 by welding. Reference numeral 9 denotes a piezoelectric ceramic bonded to the upper surface of the vibration plate 8, and a metal pad 10 is bonded to the upper surface of the piezoelectric ceramic 9. Reference numeral 11 denotes an O-ring inserted into an annular groove formed in the opening of the base 3.

Next, the configuration of the connector block 2 will be described. Reference numeral 12 denotes a connector unit made of an insulator, and a terminal 13 is fixed inside the connector unit 12. 14 is a metal ring,
The connector unit 12 is fixed to the outer periphery of the large diameter portion. Reference numeral 15 denotes a connector for extracting an electric signal from the terminal 13 to an external knock controller (not shown).
Reference numeral 16 denotes a base at which the terminal 13 projects below the connector unit 12 and a sleeve 7 of the base block 1.
This is a sealant filled in. Reference numeral 17 denotes a lead portion of the terminal 13, and a lead wire 18 is spot-welded. The other end of the lead wire 18 is the pad 1 of the base block 1.
Connected to 0.

Next, a procedure for assembling the knock sensor of the above embodiment will be described. As shown in FIG. 2, a vibration plate 8 in which a piezoelectric ceramic 9 and a pad 10 are bonded to a projection 4 of a base 3 is welded, a sealing agent 16 is filled in a sleeve 7, and the base block 1 is assembled. Lead wire 18
Is spot welded to the pad 10 and the lead wire 18
Is spot-welded to the lead portion 17 of the terminal 13. Thereafter, as shown in FIG. 1, the lead portion 17 is inserted into the sealant 16 filled in the sleeve 7, and
With the lower surface of the connector block 2 contacting the upper surface of the base block 1 with the ring 11
And the base 3 are integrated by ring projection welding all around to complete.

When this completed knock sensor is fixed to the engine by the screw portion 5, the electrode on one side of the piezoelectric ceramic 9 is connected to the ground via the diaphragm 8, the base 3, and the engine body, and the piezoelectric ceramic 9 is connected to the ground. The other electrode 9 is a pad 10, a lead 18, a terminal 13, a connector 1
5 and electrically connected to the knock controller.

The vibration of the engine is transmitted to the vibration plate 8 and the piezoelectric ceramic 9 via the base 3, and the piezoelectric ceramic 9
An electric signal corresponding to the vibration is generated, and the electric signal is input to the knock controller. FIG. 6 shows the electrical connection between the piezoelectric ceramic 9 and the knock controller. On the knock controller side, a resistor 19 and a DC power supply 20 are connected in series between the signal line of the piezoelectric ceramic 9 and the ground.

FIG. 4 shows a diaphragm 21, in which a diaphragm 21a is formed on the outer periphery and a hole 21b is formed in the center. This diaphragm 21 can be used in place of the diaphragm 8 in the above embodiment.

[0015]

According to the present invention, as is apparent from the above embodiment, the lead wire for connecting the lead portion of the terminal and the piezoelectric ceramic is spot-welded without soldering, and the weight of the solder added to the piezoelectric ceramic is reduced. Of the knock sensor is reduced, so that the variation of the characteristics of the knock sensor is reduced.

Furthermore, since the soldering is eliminated, the silver electrode coated on the piezoelectric ceramic does not suffer from the silver erosion, and at the same time, the high temperature as in the case of soldering is not applied to the piezoelectric ceramic. This has the effect that cracks at the ceramic interface can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a knock sensor according to an embodiment of the present invention.

FIG. 2 is an exploded view of a knock sensor in the embodiment.

FIG. 3 is a top view and a front view of a diaphragm of the knock sensor according to the embodiment.

FIG. 4 is a top view and a front view of another diaphragm of the knock sensor according to the embodiment.

FIG. 5 is a front view of the knock sensor in the embodiment.

FIG. 6 is an electrical connection diagram of a knock sensor in the embodiment.

FIG. 7 is a sectional view of a conventional knock sensor.

FIG. 8 is a top view and a front view of a diaphragm of a conventional knock sensor.

FIG. 9 is a characteristic diagram of a conventional knock sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base block part 2 Connector block part 3 Base 4 Protrusion 6 Hole 7 Sleeve 8 Vibrating plate 9 Piezoelectric ceramic 10 Pad 12 Connector unit 13 Terminal 14 Ring 15 Tube part 16 Sealant 17 Lead part 18 Lead wire

Claims (2)

(57) [Claims] 1. A base having a projection and a hole in a central portion, a diaphragm having a central portion fixed to the projection, a piezoelectric ceramic joined to one surface of the diaphragm, and a piezoelectric ceramic joined to one surface of the piezoelectric ceramic. The base block is constituted by the pad provided and the sleeve inserted in the hole provided in the projection, and a connector block for fixing the terminal inside, and a ring provided at one end of the connector unit, And each end is connected to one end of the terminal and the
Has a lead wire joined to the
Knock sensor, and the one end of the terminal to secure the ring to the base is inserted into the sleeve, characterized by integrating the base block and connector block. 2. A had use a diaphragm subjected to drawing on the outer periphery
Knock sensor according to claim 1, wherein a.