JP2002039852A - Non-resonance type knock sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such as increase in the number of processes by resistance welding between an annular electrode plate and a connection terminal rod arranged on an obverse and a reverse of an annular piezoelectric element, and such as connection failure in an assembling part. SOLUTION: The connection terminal rod 21 is integrally formed projectedly with the annular electrode plates 20a, 20b, and a wall thickness of the rod 21 is thickened by a wall thickness thickening means, compared with those of the electrode plates 20a, 20b. In this constitution, the resistance welding is not required between the rod 21 and the electrode plates 20a, 20b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-resonant knock sensor which is attached to an internal combustion engine and electrically detects the occurrence of knocking.

[0002]

2. Description of the Related Art In a case attached to an internal combustion engine,
A ring-shaped piezoelectric element having a ring-shaped electrode plate disposed on the front and back sides is held in a pressed state, and a connection terminal rod electrically connected to the ring-shaped electrode plate is surrounded by a cylindrical wall on a side surface of the case. Various non-resonant knock sensors having a cylindrical connector portion protruding therefrom have been proposed, for example, in JP-A-61-153530. This non-resonant knock sensor applies a strain in the thickness direction corresponding to the knocking frequency to the piezoelectric element held in the case in accordance with the occurrence of knocking, and generates a signal voltage between the electrodes. It is designed to be taken out from the connection terminal rod of the connector part.

[0003]

Since the connecting terminal rod for inserting the connector is connected to the female coupler, the connecting terminal rod needs to have a required rigidity so as not to buckle.
On the other hand, an annular electrode plate arranged on the front and back of the annular piezoelectric element,
It is said that the thinner the annular piezoelectric element, the better the adhesion between the front and back electrodes of the annular piezoelectric element and the better the characteristics can be obtained. Therefore, conventionally, since the thickness of the connection terminal rod and the thickness of the annular electrode plate are different from each other, the connection terminal rod and the annular electrode plate are formed of different materials, respectively, and are electrically connected by resistance welding or the like.

However, since resistance welding is used as described above, the number of steps is increased, and it is necessary to check the welding state at the time of assembling, or to cause poor connection at the assembling portion due to mechanical shock or the like. There was a problem. An object of the present invention is to solve such a problem.

[0005]

SUMMARY OF THE INVENTION According to the present invention, an annular piezoelectric element having annular electrode plates disposed on the front and back surfaces is held in a case attached to an internal combustion engine in a pressure-tight manner, and a side surface of the case is provided with: In a configuration in which a cylindrical connector portion formed by surrounding a connection terminal rod electrically connected to the annular electrode plate with a cylindrical wall is provided so as to protrude, the connection terminal rod is integrally protruded from the annular electrode. A non-resonance type knock sensor characterized in that the thickness of the connection terminal rod is made larger than the thickness of the ring-shaped electrode plate by a thickness increasing means.

In this configuration, since the connecting terminal rod and the annular electrode plate are integrally formed, mutual resistance welding is not required and, of course, there is no mutual electrical connection failure. .

[0007] The thickening means includes a conductive plate having the same thickness, an annular electrode plate, a terminal main rod protruding from the annular electrode plate, and an end portion of the terminal main rod that is formed in a width direction. Forming a forming die plate comprising a folding allowance coupled to the main body by punching, and folding the folding allowance on the terminal main rod, thereby connecting the folding allowance with the terminal main rod. A device formed with a terminal rod is proposed.

[0008] Further, as another means for increasing the thickness, a conductive plate material in which a thin portion and a thick portion are coupled to each other is used. The thickness of the connection terminal rod is made larger than the thickness of the ring-shaped electrode plate by punching in accordance with the thick portion, and the connection terminal rod and the ring-shaped electrode plate are integrally formed. Suggested.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a non-resonant knock sensor will be described with reference to FIG. The synthetic resin case 1 for holding each member includes a cylindrical main body 2, and a metal sleeve 4 is mounted in the center of the cylindrical main body 2. This metal sleeve 4
In the figure, a flange portion 5 is formed at a lower portion, and a screw 7 is formed around an upper portion of the cylindrical portion 6. Further, a plurality of engagement steps are formed around the upper end of the cylindrical portion 6 and the periphery of the flange portion 5 so as to improve the bonding strength with the synthetic resin case 1.

An annular piezoelectric element 8 having an electrode layer formed on the front and back surfaces and polarized in the thickness direction is externally fitted to the cylindrical portion 6, and is brought into close contact with the front and back surfaces to form annular electrode plates 20a and 20b.
And is seated on the flange 5. Here, the upper annular electrode plate 20a (see FIG. 3) is a signal extracting electrode, and the lower annular electrode plate 20b (see FIG. 4) is a ground electrode. As will be described later, connection terminal rods 21 and 21 are formed on the electrode plates 20a and 20b so as to be eccentric to the left and right so as not to overlap with each other. Further, the connection terminal rod 21 of the upper annular electrode plate 20a is bent once (see FIG. 3), and the connection terminal rod 21 of the lower annular electrode plate 20b is bent twice (see FIG. 4) to connect the connection terminals. The ends of the rods 21 and 21 have the same height.

The annular piezoelectric element 8 and the electrode plates 20a, 2
Ob is insulated from the metal sleeve 4 by the insulating tubular piece 10. The insulating tubular piece 10 is provided with a seating portion 10 that covers the flange portion 5.
and an annular piezoelectric element 8 and an annular electrode plate 2
And an insulating tube portion 10b for insulating the inner edges of Oa and 20b from the metal sleeve 4. As described above, by continuously insulating the metal sleeve 4 from the flange 5 to the cylinder 6, the annular piezoelectric element 8, the annular electrode plates 20a, 20b are formed.
And the metal sleeve 4 is insulated.

Further, an insulating plate 11 and a weight 12 are sequentially laminated on the upper annular electrode plate 20, and a screw 7 is further disposed thereon.
And the nut 13 is arranged, and by tightening the screw,
Each member is clamped and held between the flange 5 and the nut 13. Then, the synthetic resin case 1 is molded around the metal sleeve 4. The synthetic resin case 1 has a cylindrical connector 17 from the peripheral surface of the main body 2.
And surrounds the tapered tips 22, 22 (one of which is hidden and invisible) of the two connection terminal rods 21, 21 in the cylindrical wall 16. The connection terminal rods 21 and 21
Generates a potential difference corresponding to the strain in the thickness direction of the piezoelectric element 8 due to the occurrence of knocking. In order to extract this potential difference as a signal voltage, a female coupler 19 is fitted to the connector section 17 and connected to the connection terminal rods 21 and 21.

In the present invention, the connection terminal rods 21, 21 and the electrode plates 20a, 20b are integrally formed as a main part, and such a configuration will be described in detail. Since the connection terminal rods 21 and 21 inserted into the connector portion 17 are connected to the female coupler 19, they need to have required rigidity so as not to buckle. On the other hand, the thinner the annular electrode plates 20a and 20b arranged on the front and back of the annular piezoelectric element 8, the more the adhesion to the front and back electrodes of the annular piezoelectric element 8 is ensured, and good characteristics can be obtained. Therefore, in the present invention, the connecting terminal rods 21 and 21 are connected to the annular electrode plates 20a and 20b.
And the connection terminal rods 21 and 21 and the annular electrode plates 20a and 20b are integrated. Further, the thickness of the connection terminal rods 21 and 21 is made larger than the thickness of the annular electrode plates 20a and 20b by the thickening means. The distal ends 22 of the connection terminal rods 21 and 21 are tapered to facilitate connection with the female coupler 19.

FIG. 5 shows such a first thickening means. Here, first, from a conductive plate material having the same thickness, an annular electrode plate 20a (20b), a terminal main rod portion 31 protruding from the annular electrode plate 20, and both ends of the terminal main rod portion 31 in the width direction. The forming die plate 30 including the coupled folding allowances 32 is formed by punching. Folding allowance 3
The width of 2, 32 is a half width of the terminal main rod portion 31. Further, in order to form the tapered tip 22, a V-shaped cut 34 is formed in advance between the terminal main rod portion 31 and the folding allowance portion 32. Here, the thickness of the conductive plate material is 0.4 mm, and plating is performed as necessary.

Then, the folding allowances 32, 32 are respectively folded and crushed on the terminal main rod 31 along the dashed line in FIG. 5, and overlapped as shown in FIG. Next, in order to make the tip 22 tapered in the thickness direction, as shown in FIG. 7, tapered surfaces 35, 35 are formed on the upper and lower surfaces by press molding. Further, the connection terminal rod 21 of the upper annular electrode plate 20a is bent once (see FIG. 3), and the connection terminal rod 21 of the lower annular electrode plate 20b is bent twice (see FIG. 4).

Next, the second thickening means will be described with reference to FIGS. In this configuration, as shown in FIG.
Conductive plate material 4 in which thin portion 41 and thick portion 42 are coupled
0 is used. Here, the thin portion 41 is 0.4 mm and the thick portion 4
2 is 0.8 mm, and is plated if necessary. Then, the annular electrode plate 20 is made to coincide with the thin portion 41,
Punching is performed by making at least the end of the connection terminal rod 21 coincide with the thick part 42. Thereby, as shown in FIG. 10, the thickness of the distal end 22 of the connection terminal rod 21 is
And the thickness of the connection terminal rod 21 and the annular electrode plates 20a and 20b excluding the tip 22 becomes the thickness of the thin portion 41.
Here, similarly to the above, in order to make the tip 22 tapered in the thickness direction, tapered surfaces 44 are formed on the upper and lower surfaces by press molding. Then, the connecting terminal rod 21 is bent to form the annular electrode plate 20b (20a) in FIG. Thus, the connection terminal rod 21 and the annular electrode plate 20b (20a) can be integrated while varying their thickness.

[0017]

According to the non-resonant knock sensor of the present invention, the connecting terminal rod is formed integrally with the annular electrode plate and the thickness of the connecting terminal rod is reduced by the thickening means. Since the thickness is larger than the wall thickness, the number of steps can be reduced without the need for resistance welding between the connection terminal rod and the annular electrode plate, the confirmation of electrical connection is not required, the assembly is easy, and No mutual electrical connection failure occurs.

Further, as the means for increasing the thickness, an annular electrode plate, a terminal main rod protruding from the annular electrode plate, and an end portion of the terminal main rod are connected in the width direction from a conductive plate having the same thickness. By forming a forming die plate including a folded part that is formed and projected by punching, and by folding the folded part on the terminal main rod part, a folding part and a terminal main rod part are formed. In the case where the connecting terminal rod is formed, since it is formed by a punching process of a forming die plate and a bending process, it can be easily manufactured simply by increasing the bending process. it can.

Further, as another means for increasing the thickness, a conductive plate material in which a thin portion and a thick portion are coupled to each other is provided by matching the annular electrode plate with the thin portion and forming at least an end portion of the terminal main rod portion to be thick. The thickness of the connection terminal rod is made larger than the thickness of the ring-shaped electrode plate by performing a punching process in accordance with the thickness of the connection portion, and the connection terminal rod and the ring-shaped electrode plate are integrally formed. In other words, as a working material to be punched in advance, it is sufficient to prepare a conductive plate material in which a thin portion and a thick portion are coupled,
This also facilitates manufacture.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a non-resonant knock sensor.

FIG. 2 is a plan view of an upper annular electrode plate 20a having a connection terminal rod 21 formed by a first thickening means.

FIG. 3 shows an upper annular electrode plate 20 having a connecting terminal rod 21;
It is a side view of a.

FIG. 4 shows a lower annular electrode plate 20 having a connecting terminal rod 21.
It is a side view of b.

FIG. 5 is a plan view of a main part of the molding die plate 30.

FIG. 6 is a plan view of the connection terminal rod 21 formed by the first thickening means.

FIG. 7 is a side view of the connection terminal rod 21 formed by the first thickening means.

FIG. 8 is a plan view of an annular electrode plate 20a (20b) having a connection terminal rod 21 formed by a second thickening means.

9 is a vertical sectional side view of a conductive plate member 40. FIG.

FIG. 10 is a vertical sectional side view of a connection terminal rod 21 formed by a second thickening means.

[Explanation of symbols]

 Reference Signs List 8 annular piezoelectric element 20a, 20b annular electrode plate 21 connecting terminal rod 30 forming mold plate 40 conductive plate material

Claims (3)

[Claims] An annular piezoelectric element having an annular electrode plate disposed on the front and back surfaces is held in a case attached to an internal combustion engine in a sandwiching manner, and is electrically connected to the annular electrode plate on a side surface of the case. The connection terminal rod is formed by projecting a cylindrical connector portion that is formed by surrounding the connection terminal rod with a cylindrical wall. A non-resonant knock sensor, wherein the thickness of the connection terminal rod is larger than the thickness of the annular electrode plate. 2. The method according to claim 1, wherein the thickening means comprises:
An annular electrode plate, a terminal main rod portion projecting from the annular electrode plate, and a forming template plate formed by a folding margin portion coupled to an end of the terminal main rod portion in the width direction are formed by punching. 2. The non-resonant knock sensor according to claim 1, wherein the folding margin is folded on the terminal main rod to form a connection terminal rod with the folding margin and the terminal main rod. 3. The method according to claim 1, wherein the thickening means matches the conductive plate material, in which the thin portion and the thick portion are coupled, with the annular electrode plate to the thin portion,
The thickness of the connection terminal rod is made larger than the thickness of the ring-shaped electrode plate by punching out at least the end of the terminal main rod portion so as to correspond to the thick portion, and the connection terminal rod and the ring-shaped electrode plate are formed. 2. The non-resonant knock sensor according to claim 1, wherein said knock sensor is integrally formed.