JP2800521B2 - 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 which utilizes a knock control system for an automobile or the like to determine the presence or absence of knocking of an engine to control ignition timing.

[0002]

2. Description of the Related Art A knock control system for controlling ignition timing by determining the presence or absence of engine knocking is used in automobiles and the like. In this knock control system, the vibration of the engine block is detected, the presence or absence of knocking is detected from the vibration waveform, and ignition timing control is performed to improve fuel efficiency. Knocksen is used to detect this vibration.

FIGS. 5 and 6 show the structure of a conventional knock sensor. First, the base will be described.

In FIGS. 5 and 6, reference numeral 1 denotes a conductive base on which a screw portion 2 is integrally formed, and a truncated cone-shaped projection is integrally formed at the center of the base 1. 4 is the base 1
A sleeve 11 made of an insulating material is inserted into the hole 4, and the sleeve 11 is filled with a potting agent 12 a. Reference numeral 5 denotes a metal diaphragm, and a hole is formed in the center of the diaphragm 5. This diaphragm is fixed to the projection 3 of the base 1 by welding. Reference numeral 6 denotes a piezoelectric ceramic element adhered to one surface of the diaphragm 5, a hole is provided in the center, and a pad 7 is joined to the other surface. The diameter of the pad 7 is equal to or less than the diameter of the ring projection provided on the upper end of the projection 3 before the projection 3 and the diaphragm 5 are joined. Reference numeral 10 denotes an O-ring housed in an annular groove formed on the upper surface of the base 1. Reference numeral 19 denotes an annular groove formed on the upper surface of the base 1.

Next, the configuration of the resin case block B will be described. Reference numeral 14 denotes a resin case in which the wire harness fixing wall 20 is integrally formed. A terminal is fixed to the center of the inside of the resin case 14, and the upper part is entirely concave. The wire 34 of the wire harness is in the recess.
The shrink tube 32 and a part of the shrink tube 31 are fixed. The wire 34 of the wire harness is fixed by caulking at the upper end of the terminal 9 and the shrink tube 31
Are fixed to the wire harness fixing wall 20 with the cable ties 17.

A potting agent 1 is applied to the joint between the terminal 9 and the resin case 14 which comes out from the upper part of the resin case 14.
2b is filled. Reference numeral 13 denotes a metal ring fixed to the lower periphery. After the wire harness is fixed, the entire recess of the resin case 14 is filled with the potting agent 15.

The base block A and the resin case block B constructed as described above are separately assembled, and then the pads 7 and the lead portions 9a of the terminals 9 are soldered with the lead wires 8 to connect the terminals 9 to the pads 7, The piezoelectric ceramic element 6 penetrates through the center hole of the diaphragm 5 and is inserted into the hole of the sleeve 11. Further, the ring 13 and the base 1 are integrated by ring projection welding all around to complete.

After this completion, the lead portion 9a of the terminal 9
Is connected to the lead wire 8, pad 7, and one surface of the piezoelectric ceramic element 6, and the other surface of the piezoelectric ceramic element 6 is electrically connected to the diaphragm 5 and the base 1.

The screw portion 2 of the base 1 of the knock sensor having this configuration is screwed into a screw hole of an engine block (not shown) and connected to the ground. Terminal 9 is connected to the knocking controller via a wire cable.

[0010]

However, in the conventional knock sensor, since the diameter of the pad is small, it is conceivable that cracks may occur in the piezoelectric ceramic element due to strong vibration generated in the engine block.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an excellent knock sensor capable of effectively preventing cracks from being generated in a piezoelectric ceramic element.

[0012]

In order to achieve this object, a knock sensor according to the present invention comprises: a base having a projection and a screw portion; a diaphragm having a central portion fixed to the projection; A vibrating plate is arranged on one surface and connected to a piezoelectric ceramic element having an area substantially the same as that of the vibrating plate and an electrode on the other surface of the piezoelectric ceramic element, and having an area substantially the same as the piezoelectric ceramic element. Pad and this pad
And a lead wire having ends joined thereto, a tube is inserted into a center hole of the protrusion, a potting agent is filled into the tube to form a base block, and a recess is formed at an upper end.
And the inside of the resin case
Terminal fixed to the center and lower end of the resin case
A ring fixed to the outer periphery of the portion, and
Join the upper end of the terminal and the wire harness, and
Fill the recess with a potting agent and fill the resin case block.
And the other end of the lead wire at the lower end of the terminal.
End and connect the lower end of the terminal to the tube.
Insert the ring into the base,
It is characterized in that the base block and the resin case block are integrated .

[0013]

Therefore, in the knock sensor according to the present invention, the piezoelectric ceramic element is sandwiched between the pad and the vibration plate having substantially the same area, so that the pressurization such that the piezoelectric ceramic element resonates due to the vibration from the engine block or the like. Even if it does, cracks in the piezoelectric ceramic element can be effectively prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the knock sensor according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional structure of a base block A and a resin case block B of the embodiment, and FIG. 2 shows a state where the structure shown in FIG. 1 is separated into a base block A and a resin case block B. ing. FIG. 3 shows a configuration in a plane, and FIG. 4 shows an external configuration. In the following text and drawings, the same components in the previous FIGS. 5 and 6 are denoted by the same reference numerals.

First, the configuration of the base block A will be described. 1, 2 and 3, reference numeral 1 denotes an electrically conductive base on which a screw portion 2 is integrally formed. In the center of the base 1, a frustoconical projection is integrally formed. 4 is the base 1
A sleeve 11 made of an insulating material is inserted into the hole 4, and the sleeve 11 is filled with a potting agent 12a. Reference numeral 5 denotes a metal diaphragm, and a hole is formed in the center of the diaphragm 5. This diaphragm is fixed to the projection 3 of the base 1 by welding. Reference numeral 6 denotes a piezoelectric ceramic element bonded to one surface of the diaphragm 5, a hole is provided in the center, and a pad 21 is joined to the other surface. The diameter of the pad 21 is slightly smaller than the diameter of the piezoelectric ceramic element 6.

Reference numeral 10 denotes an O-ring housed in an annular groove formed on the upper surface of the base 1. Reference numeral 19 denotes an annular groove formed on the upper surface of the base 1.

Next, the configuration of the resin case block B will be described. Reference numeral 14 denotes a resin case in which the wire harness fixing wall 20 is integrally formed. A terminal is fixed in the center of the inside of the resin case 14, and the upper part is entirely recessed.
The shrink tube 32 and a part of the shrink tube 31 are fixed. The wire 34 of the wire harness is fixed by caulking at the upper end of the terminal 9. The contraction tube 31 is attached to the wire harness fixing wall 20 by the cable tie 1.
It is fixed at 7.

The joint between the terminal 9 and the resin case 14 projecting from the upper part of the resin case 14 is filled with a potting agent 12b. 13 is a connector unit 21
Is a metal ring fixed to the outer periphery of the lower part of. After fixing the wire harness, the potting agent 15 is filled in the entire recess of the resin case 14.

The base block A and the resin case block B are separately assembled, and thereafter, the lead wire 8 between the pad 21 and the lead portion 9a of the terminal 9 is soldered, and the terminal 9a is connected to the pad 21 and the piezoelectric ceramic element. 6. Penetrate through the center hole of diaphragm 5 and insert into hole of sleeve 11. Further, the ring 13 and the base 1 are integrated by ring projection welding all around to complete.

In this case, the lead portion 9a of the terminal 9 is connected to the lead wire 8, the pad 21, and one surface of the piezoelectric ceramic element 5, and the other surface of the piezoelectric ceramic element 6 is connected to the diaphragm 5 and the base 1. Conduct.

The screw portion 2 of the base 1 of the knock sensor is screwed into a screw hole of the engine block and connected to the ground. Terminal 9 is connected to the knocking controller through a wire cable.

[0023]

As is apparent from the above description, in the knock sensor of the present invention, the piezoelectric ceramic element is sandwiched between the pad and the diaphragm having substantially the same area.
Even if pressure is generated such that the piezoelectric ceramic element resonates due to vibration from the engine block or the like, cracking of the piezoelectric ceramic element can be effectively prevented.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a state where the base and the resin case are separated from each other in the embodiment.

FIG. 3 is a front view showing a configuration related to a front in the embodiment.

FIG. 4 is a side view showing an external configuration in the embodiment.

FIG. 5 is a cross-sectional view showing a configuration of a conventional knock sensor.

6 is a front view of the conventional example shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Screw part 3 Projection part 4 Hole 5 Vibration plate 6 Piezoelectric ceramic element 8 Lead wire 9 Terminal 9a Lead part 9 Terminal 10 O (O) ring 11 Sleeve 12a Potting agent 13 Ring 14 Resin case 21 Pad

Claims (1)

(57) [Claims] 1. A base having a protrusion and a screw portion, a diaphragm having a central portion fixed to the protrusion, and the diaphragm being disposed on one surface, and having an area substantially equal to that of the diaphragm. A pad connected to the same piezoelectric ceramic element and an electrode on the other surface of the piezoelectric ceramic element, the pad having substantially the same area as the piezoelectric ceramic element, and one end joined to the pad;
A lead wire , a tube is inserted into a center hole of the protrusion, a potting agent is filled in the tube to form a base block, and a recess is formed at an upper end. Was
It is fixed to the resin case and the inner central part of this resin case.
Terminal and fixed to the outer periphery of the lower end of the resin case
The terminal at the depression
The upper end of the wire harness and the wire harness, and
The resin case block is filled with
When the other end of the lead wire is connected to the lower end of the terminal
Both insert the lower end of the terminal into the tube,
By joining the ring to the base, the base block
A knock sensor characterized by being integrated with a resin case block .