JPH0921697A - Vibration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration sensor, which does not yield looseness in a lead conductor in a housing and can be assembled readily. SOLUTION: A first housing 1 has an inner space 11, and the inner space 11 has an opening part 13 on the side facing the bottom part 12. A vibration detecting part 2 is contained in the inner space 11 and fixed to the bottom part 12. Electrode terminal members 22 and 23 of the vibration detecting part 2 are fixed to the bottom part 12 together with a vibration sensitive element 21 in the inner space 11. Contact parts 221 and 231 are in contact with electrodes 212 and 213 of the vibration sensitive element 21. Lead terminal parts 222 and 232 are guided out in the direction toward the opening part 13. A second housing 3 has terminal conductors 31 and 32, which are guided out to the external part and are airtightly connected to the first housing 1 on the side of the opening part 13 of the first housing 1. The terminal conductors 31 and 32 are brought into contact with the lead terminal parts 222 and 232.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vibration sensor. The vibration sensor according to the present invention is used, for example, for knocking detection of an internal combustion engine such as an automobile.

[0002]

2. Description of the Related Art A vibration sensor for detecting knocking of an internal combustion engine and performing feedback control of ignition timing is roughly classified into a resonance type and a non-resonance type.

The resonance type vibration sensor is designed so that the resonance frequency of the vibration sensor is matched with the knocking frequency of the internal combustion engine to be detected, and generally, a thin piezoelectric element is attached to a disc-shaped metal plate to form the resonance frequency. It has a detector that supports the center. The detector vibrates in a bending mode according to the vibration acceleration applied to the vibration sensor. The characteristic of this method is that the detection sensitivity is high because the resonance of the detection unit is used, and S
/ N is good. Further, since the vibration sensor itself has the function of a bandpass filter, there is an advantage that the signal processing circuit can be simplified. However, since it is necessary to change the resonance frequency specification for each engine model, there is a problem in that a vibration sensor according to the engine model must be provided. A frequency adjusting step is also necessary in the manufacturing process.

In the non-resonant type vibration sensor, a mass body is superposed on a piezoelectric element installed on a vibrating surface, and a force generated by a vibration acceleration applied to the mass body distorts the piezoelectric element in its thickness direction. In general, a vibration sensor that uses this method uses the vibration mode in the thickness direction of the piezoelectric element, so it is possible to set a resonance frequency of the detection unit that is sufficiently higher than the knocking frequency. Since a flat sensitivity characteristic can be obtained in a wide band, and therefore, the engine type is not selected, the versatility is excellent, and the frequency adjustment step is unnecessary in the manufacturing process.

As described above, both the resonance type and the non-resonance type have their advantages and disadvantages, and therefore, they are used properly according to the design of the system.

When used as a knock sensor, the vibration sensor is mounted on the engine block of an internal combustion engine. Therefore, the housing of the knock sensor must have a structure that can accurately transmit the vibration of the engine block to the vibration detector and protect the detector even in a bad environment. The structure of such a vibration sensor is disclosed in, for example, JP-A-56-49925, JP-A-57-39335, JP-A-62-128332, and the like. The vibration sensor described in these prior art documents includes a lower housing, a piezoelectric element serving as a vibration sensing element, an electrode terminal member, and an upper housing. The lower housing has an internal space, and the internal space has an opening on the side facing the bottom. The piezoelectric element is housed inside the internal space and fixed to the bottom. The electrode terminal member is fixed to the bottom together with the piezoelectric element in the internal space. The upper housing has a terminal conductor led out to the outside, and is airtightly coupled to the lower housing on the opening side of the first housing. The lead terminal portion of the electrode terminal is connected to the terminal conductor using a lead wire.

At the time of assembly, the assembly of the piezoelectric element and the electrode terminal is inserted into the lower housing through the opening of the lower housing, and the assembly of the piezoelectric element and the electrode terminal is moved to the lower part by using a fastener such as a screw. After mounting and fixing in the housing, the lead wire connects between the electrode terminal and the terminal conductor provided in the upper housing. After this, the upper housing is airtightly fitted and fixed in the opening of the lower housing.

Since such an assembling process is required, the lead wire connecting the lead terminal portion of the electrode terminal and the terminal conductor needs to be considerably longer than the length actually required in the assembled state.

As described above, in the conventional vibration sensor,
A structure in which an electrode terminal member fixed to the lower housing and a terminal conductor provided in the upper housing, which is coupled to the lower housing, are connected by an unnecessarily long lead wire together with the piezoelectric element forming the vibration sensing element. Because I was taking
Loose lead wires. Since it is necessary to avoid electrical contact between the lead wire and the housing due to the looseness of the lead wire, it is necessary to use a lead wire having an insulating coating. Further, due to the looseness of the lead wire, there is a risk of causing an accident such as the lead wire being caught between the lower housing and the upper housing during the assembling process. Therefore, it was not possible to adopt a highly efficient automatic assembly process. Further, there is a problem that the reliability of vibration resistance is low.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration sensor capable of accurately transmitting the vibration to be detected to the vibration detecting section.

Another object of the present invention is to provide a vibration sensor having an airtight structure capable of protecting the vibration detecting portion even in a bad environment.

Yet another object of the present invention is to provide a vibration sensor which does not cause slack in the lead conductor in the housing.

Still another object of the present invention is to provide a vibration sensor having high reliability with respect to vibration resistance.

Yet another object of the present invention is to provide a vibration sensor that is easy to assemble.

Yet another object of the present invention is to provide a vibration sensor which does not require the use of a lead conductor having an insulating coating within the housing.

Still another object of the present invention is to provide a vibration sensor which has no room for causing an accident such as a lead conductor being sandwiched between housing constituent members in the assembly process.

Still another object of the present invention is to provide a vibration sensor capable of adopting a highly efficient automatic assembly process.

[0018]

In order to solve the above-mentioned problems, a vibration sensor according to the present invention includes a first housing, a vibration detecting portion, and a second housing. The first housing has an internal space, and the internal space has an opening on the side facing the bottom. The vibration detection unit includes a vibration sensing element and an electrode terminal member, is housed inside the internal space, and is fixed to the bottom portion. The electrode terminal member has a contact portion and a lead terminal portion, is fixed to the bottom portion together with the vibration sensing element in the internal space, and the contact portion contacts the electrode of the vibration sensing element. ,
The lead terminal portion is continuous with the contact portion and is led out in the direction of the opening. The second housing has a terminal conductor led out to the outside, is airtightly coupled to the first housing on the opening side of the first housing, and the terminal conductor is in contact with the lead terminal portion. doing.

As described above, the first housing has the internal space, and the vibration detector is housed inside the internal space of the first housing and fixed to the bottom. According to this structure, when used as a knock sensor, the vibration of the engine block can be accurately transmitted to the vibration detection unit by mounting the first housing at an appropriate position on the engine block of the internal combustion engine or the like.

The second housing is hermetically coupled to the first housing on the opening side of the first housing.
Therefore, it is possible to obtain a vibration sensor having an airtight structure that can protect the vibration detection unit even in a bad environment such as when used as a knock sensor for an internal combustion engine.

Since the internal space of the first housing has an opening on the side facing the bottom, the vibration detecting section is
It can be inserted into the first housing through the opening of the housing and securely fixed in the first housing.

The electrode terminal member constituting the vibration detecting portion is fixed to the bottom together with the vibration sensing element in the internal space. With this, the electrode terminal member can be integrally coupled with the vibration sensing element in the first housing.

Since the contact portion of the electrode terminal member is in contact with the electrode of the vibration sensing element, the electrode of the vibration sensing element can be pulled out through the electrode terminal member. Since the electrode terminal member has the lead terminal portion and the lead terminal portion is continuous with the contact portion, the electrode of the vibration sensing element can be pulled out through the contact portion of the electrode terminal member and the lead terminal portion. .

The lead terminal portion of the electrode terminal member is led out in the direction of the opening, and the second housing has a terminal conductor led out to the outside, and the terminal conductor is in contact with the lead terminal portion. According to this structure, only by connecting the second housing to the first housing, the lead terminal portion of the electrode terminal member fixed to the first housing and the second housing can be provided.
The terminal conductor provided in the housing can be electrically connected by direct contact between the two. It is not necessary to connect a lead wire between the lead terminal portion of the electrode terminal member and the terminal conductor.

Therefore, it is possible to obtain the vibration sensor in which the lead conductor is not loosened in the housing. Moreover,
There is no room for deterioration of vibration resistance due to loosening of the lead wire. Further, by simply connecting the second housing to the first housing, the lead terminal portion of the electrode terminal member fixed to the first housing and the terminal conductor provided in the second housing are electrically connected. Since it can be electrically connected to, it is easy to assemble.

Further, the lead terminal of the electrode terminal member and the second
Since it directly contacts with the terminal conductor provided in the housing, it is not necessary to use a lead conductor having an insulating coating inside the housing, and the assembling workability is further improved. Moreover, there is no room for an accident such as the lead conductor being sandwiched between the first housing and the second housing in the assembly process. As a total effect of these, it becomes possible to adopt a highly efficient automatic assembly process.

Other features of the present invention and the effects thereof will be described in more detail with reference to the accompanying drawings.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The vibration sensor according to the present invention is mainly mounted on an engine block of an internal combustion engine and used as a knock sensor, but it is also used as vibration detection means in other technical fields. You can also do it. 1 is a plan view of a vibration sensor according to the present invention, FIG. 2 is a sectional view taken along line A2-A2 of FIG. 1, FIG. 3 is a sectional view taken along line A3-A3 of FIG. 1, and FIG. 4 is an exploded view of the vibration sensor shown in FIG. 3. FIG. The vibration sensor according to the present invention includes a first housing 1, a vibration detection unit 2, and a second housing 3. The first housing 1 has an internal space 11, and the internal space 11 has an opening 13 on the side facing the bottom 12.
have.

The vibration detector 2 includes a vibration sensitive element 21 and electrode terminal members 22 and 23, is housed inside the internal space 11 and is fixed to the bottom 12. Electrode terminal member 22
Has a contact portion 221 and a lead terminal portion 222.
The lead terminal portion 222 is continuous with the contact portion 221, and the opening 13
Has been derived in the direction of.

Like the electrode terminal member 22, the electrode terminal member 23 also has a contact portion 231 and a lead terminal portion 232. These electrode terminal members 22 and 23 are fixed to the bottom 12 together with the vibration sensing element 21 in the internal space 11. The contact portions 221 and 231 are the body 21 of the vibration sensing element 21.
The electrodes 212 and 213 provided on both surfaces of the No. 1 are in contact with each other. The lead terminal portions 222 and 232 are contact portions 22.
1 and 231 are led out in the direction of the opening 13. The second housing 3 has terminal conductors 31 and 32 that are led to the outside, and is airtightly coupled to the first housing 1 on the opening 13 side of the first housing 1.
The terminal conductor 31 is the lead terminal portion 222 of the electrode terminal member 22.
And the terminal conductor 32 is in contact with the lead terminal portion 232 (not shown) of the electrode terminal member 23.

As described above, since the first housing 1 has the internal space 11 and the vibration detecting portion 2 is housed inside the internal space 11 of the first housing 1 and fixed to the bottom portion 12, the knocking is performed. When used as a sensor, the first housing 1 can be mounted at a suitable position such as on the engine block 4 (see FIG. 2) of the internal combustion engine. Thereby, the vibration of the engine block 4 can be accurately transmitted to the vibration detection unit 2. The internal space 11 of the first housing 1 has an opening 13 on the side facing the bottom 12. Therefore, the vibration detector 2 is inserted into the first housing 1 through the opening 13 of the first housing 1,
It can be securely fixed in the first housing 1.

The second housing 3 is the first housing 1
Is airtightly coupled to the first housing 1 on the side of the opening 13. Therefore, for example, even when used as a knock sensor of an internal combustion engine, even in a bad environment,
A vibration sensor having an airtight structure capable of protecting the vibration detection unit 2 can be obtained.

The electrode terminal members 22 and 23 have an internal space 11
Inside, it is fixed to the bottom 12 together with the vibration sensing element 21. Thereby, the electrode terminal members 22 and 23 are connected to the first
In the housing 1 of FIG.

Since the contact portion 221 of the electrode terminal member 22 is in contact with the electrode 212 of the vibration sensing element 21, the vibration sensing element 2
One electrode 212 can be drawn out via the electrode terminal member 22. The electrode terminal member 22 has a lead terminal portion 22.
2 and the lead terminal portion 222 is continuous with the contact portion 221, the electrode 212 of the vibration sensing element 21 can be pulled out through the contact portion 221 and the lead terminal portion 222 of the electrode terminal member 22. . Similarly to the electrode terminal member 22, the electrode terminal member 23 also has the contact portion 231 in contact with the electrode 213 of the vibration sensing element 21, so that the electrode 2 of the vibration sensing element 21 is in contact.
13 can be pulled out through the electrode terminal member 23. The electrode terminal member 23 has a lead terminal portion 232.
Since the lead terminal portion 232 is continuous with the contact portion 231, the electrode 213 of the vibration sensing element 21 can be pulled out via the contact portion 231 of the electrode terminal member 23 and the lead terminal portion 232.

The lead terminal portion 222 of the electrode terminal member 22 is led out in the direction of the opening 13, the second housing 3 has a terminal conductor 31 led out to the outside, and the terminal conductor 31 is the lead terminal portion. 222 is in direct contact. According to this structure, only by connecting the second housing 3 to the first housing 1, the lead terminal portion 222 of the electrode terminal member 22 fixed to the first housing 1,
The terminal conductor 31 provided in the second housing 3 can be electrically conducted by direct contact between the two. It is not necessary to connect a lead wire between the lead terminal portion 222 of the electrode terminal member 22 and the terminal conductor 31.

The lead terminal portion 232 of the electrode terminal member 23
Is also led out in the direction of the opening 13, the second housing 3 has a terminal conductor 32 led to the outside, and the terminal conductor 32 is in contact with the lead terminal portion 232. Therefore, by simply connecting the second housing 3 to the first housing 1, the lead terminal portion 232 of the electrode terminal member 23 fixed to the first housing 1 and the second housing 3 are provided. The contact between the terminal conductor 32 and the terminal conductor 32 can be electrically conducted. Between the lead terminal portion 232 of the electrode terminal member 23 and the terminal conductor 32,
No need to connect by leads.

Therefore, the vibration sensor in which the lead conductors are not loosened in the housings 1 and 3 can be obtained. Moreover, there is no room for deterioration of vibration resistance due to slack of the lead wire. In addition, the lead terminal portion 22 of the electrode terminal members 22 and 23 fixed to the first housing 1 is obtained only by connecting the second housing 3 to the first housing 1.
Since the terminals 2 and 232 and the terminal conductors 31 and 32 provided in the second housing 3 can be electrically connected to each other, the assembly is easy.

Further, the lead terminals of the electrode terminal members 22 and 23 and the terminal conductor 31 provided in the second housing 3,
Since it comes into contact with 32, it is not necessary to use a lead conductor having an insulating coating in the housings 1 and 3, and the workability of assembly is further improved. Moreover, there is no room for an accident such as the lead conductor being sandwiched between the first housing 1 and the second housing 3 in the assembly process.

In the embodiment, the lead terminal portion 222 is
It has a spring portion 223, and the spring portion 223 is in spring contact with the terminal conductor 31. The lead terminal portion 232 also has a spring portion 233 (not shown), and the spring portion 233 is in spring contact with the terminal conductor 32. According to this structure, the lead terminal portions 222 and 232 of the electrode terminal members 22 and 23, which are electrically connected to the electrodes 212 and 213 of the vibration sensing element 21, and the terminal conductors 31 and 32 provided in the second housing 3, The contact can be made even more reliably. The spring portions 223 and 233 are configured by, for example, leaf springs or the like, and are provided between the terminal conductor 31 and the lead terminal portion 222 of the electrode terminal member 22 and the terminal conductor 3.
2 and the lead terminal portion 232 of the electrode terminal member 23.

The vibration sensing element 21 is a piezoelectric element. The vibration detector 2 includes a mass body 24 integrally coupled with a piezoelectric element forming the vibration sensitive element 21. The piezoelectric element and the mass body 24 constituting the vibration sensitive element 21 are fixed to the bottom portion 12 of the first housing 1 by means of screwing or the like by a coupling member 25 penetrating the both. According to this structure, a non-resonant vibration sensor can be obtained. The non-resonance type vibration sensor is a system in which a piezoelectric element constituting the vibration sensitive element 21 is distorted in the thickness direction by an force generated by the vibration acceleration applied to the mass body 24 to obtain an electric signal. In the vibration sensor of this type, since the vibration mode in the thickness direction of the piezoelectric element forming the vibration sensing element 21 is used, it is possible to set the resonance frequency of the detection unit sufficiently higher than the knocking frequency. Therefore, flat sensitivity characteristics can be obtained in a wide band, excellent in versatility regardless of engine type, and a frequency adjusting step is unnecessary in the manufacturing process.

FIG. 5 is an exploded perspective view of the vibration detector 2.
The vibration sensing element 21 made of a piezoelectric element sandwiched between the electrode terminal members 22 and 23 is arranged on the insulating plate 26, and the insulating plate 27, the mass body 24 and the disc spring 28 are superposed on the vibration sensing element 21, and the whole is stopped. 25 (see FIGS. 2 and 3). Insulating plate 26, electrode terminal member 22, vibration sensing element 21, electrode terminal member 23, insulating plate 27, mass body 2
4 and the belleville spring 28 have through holes 261, 223, 214, 233, 274, 241 and 28 through which the stopper 24 penetrates.

The vibration detecting section 2 is provided inside the internal space 11.
It is stored except the upper space 111. The lead terminal portion 222 of the electrode terminal member 22 is led out to the upper space 111. The second housing 3 is the first housing 1
Is positioned in the upper space 111 of the. Preferably, the upper space 111 is unrolled more than the space for housing the vibration detecting unit 2, and thereby a step is formed between the upper space 111 and the space for housing the vibration detecting unit 2. The second housing 3 is positioned on the step surface 14 generated by the step. In the positioned state, the opening edge 15 of the first housing 1 is crimped to the surface of the second housing 34.

The second housing 3 includes the first member 33.
And a second member 34. The first member 33 and the second member 34 are made of an electrically insulating material, such as insulating plastic or insulating ceramic. The first member 33 is arranged on the vibration detector 2. The second member 34 holds the terminal conductors 31 and 32, has a connector portion 3411 on the upper surface, and is assembled on the first member 33. Connector part 341
Terminal conductors 31 and 32 are introduced into the inside of. The other ends of the terminal conductors 31 and 32 are bent along the lower surface of the second member 34. The second member 34 is the first member 3
3 is placed on top of the airtight sealing member 3 such as an O-ring.
5 is provided. The end edge of the first housing 1 is bent and fixed to the upper surface of the second member 34, whereby the whole is airtightly fixed.

The first housing 1 is preferably made of aluminum. In recent years, aluminum cast engine blocks have come to be widely used. Therefore, by constructing the first housing 1 from aluminum, it is not necessary to attach the first housing 1 to the engine block by means such as screwing. It is possible to prevent damage to the engine block due to the tightening force of the. First
The housing 1 has a threaded portion 16 which is a mounting portion for the engine block.

In order to maintain airtightness, a bonding interface between the first housing 1 and the second housing 3 and the first member 33 and the second member 34 constituting the second housing 3 or the terminal conductor 31. It is desirable to seal the lead-out portions of 32 and 32 with a sealant. A heat resistant resin such as a silicone resin or an epoxy resin can be used as the sealant.

Further, in the embodiment, the recess 343 is provided in the second member 34 constituting the second housing 3, and the recess 34 is provided.
A resistor 36 is arranged inside the unit 3. FIG. 6 shows an electric circuit connection diagram of the resistor 36 and the vibration sensing element 21. Resistance 3
Reference numeral 6 is connected in parallel with the vibration sensing element 21. Usually, the vibration sensor and the signal processing circuit are connected using a cable and a connector. However, in a vibration sensor using a piezoelectric element as the vibration sensitive element 21, the output impedance of the piezoelectric element is usually very high because the insulation resistance of the piezoelectric element is very high. Therefore, even if a cable break or a connector connection failure occurs, it is impossible to detect it. As shown in this embodiment, the resistance 3 is connected in parallel to the vibration sensing element 21 composed of a piezoelectric element.
If 6 is connected, the above-mentioned problem can be solved. Resistance 36
Has a resistance value of several hundred kΩ to several MΩ. The resistor 36 may be provided not at the inside of the vibration sensor but at the input stage of the processing circuit.

In the embodiment, the non-resonance type vibration sensor is shown, but a resonance type vibration sensor can be similarly applied.

[0048]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a vibration sensor capable of accurately transmitting the vibration to be detected to the vibration detection unit. (B) It is possible to provide a vibration sensor having an airtight structure that can protect the vibration detection unit even in a poor environment. (C) It is possible to provide a vibration sensor in which the lead conductor is not loosened in the housing. (D) It is possible to provide a vibration sensor having high reliability with respect to vibration resistance. (E) It is possible to provide a vibration sensor that can be easily assembled. (F) It is possible to provide a vibration sensor that does not require the use of a lead conductor having an insulating coating inside the housing. (G) It is possible to provide a vibration sensor that has no room for causing an accident such as the lead conductor being sandwiched by the housing constituent members in the assembly process. (H) It is possible to provide a vibration sensor that can adopt a highly efficient automatic assembly process.

[Brief description of drawings]

FIG. 1 is a plan view of a vibration sensor according to the present invention.

FIG. 2 is a sectional view taken along line A2-A2 in FIG.

3 is a cross-sectional view taken along the line A3-A3 of FIG.

FIG. 4 is an exploded view of the vibration sensor shown in FIGS. 1 and 2.

FIG. 5 is an exploded perspective view of a vibration detector used in the vibration sensor according to the present invention.

FIG. 6 is an electric circuit connection diagram of a resistance and a vibration sensing element used in the vibration sensor according to the present invention.

[Explanation of symbols]

 1 1st housing 2 Vibration detection part 3 2nd housing 22 and 23 Electrode terminal member 31 and 32 Terminal conductor

Claims (8)

[Claims] 1. A vibration sensor including a first housing, a vibration detecting portion, and a second housing, wherein the first housing has an internal space, and the internal space is a side facing a bottom portion. Has an opening portion, the vibration detection portion includes a vibration sensing element and an electrode terminal member, is housed inside the internal space, is fixed to the bottom portion, the electrode terminal member, A contact part and a lead terminal part, which are fixed to the bottom part together with the vibration sensing element in the internal space, the contact part contacts an electrode of the vibration sensing element, and the lead terminal part is The second housing has a terminal conductor that is continuous with the contact portion and is led out in the direction of the opening, and the second housing has a terminal conductor that is led out to the outside, and the first housing is provided on the opening side of the first housing. Airtightly coupled to the housing, the terminal conductor Vibration sensor in contact with the lead terminal. 2. The vibration sensor according to claim 1, wherein the lead terminal portion has a spring portion, and the spring portion is in spring contact with the terminal conductor. 3. The vibration sensor according to claim 1, wherein the vibration sensing element is a piezoelectric element. 4. The vibration sensor according to claim 3, wherein the vibration detection unit includes a mass body integrally coupled to the piezoelectric element. 5. The vibration sensor according to claim 4, wherein the piezoelectric element and the mass body are fixed to the bottom portion of the first housing by a coupling member that penetrates both the piezoelectric element and the mass body. . 6. The vibration sensor according to claim 1, wherein the vibration detection unit is housed inside the internal space, leaving an upper space, and the electrode terminal member includes the lead terminal. A vibration sensor, wherein a part is led out to the upper space, and the second housing is positioned in the upper space of the first housing. 7. The vibration sensor according to claim 6, wherein the upper space is unfolded more than a space for accommodating the vibration detection unit, and thereby the space for accommodating the upper space and the vibration detection unit. And a step is formed between the second housing and the second housing, and the second housing is positioned on a step surface generated by the step. 8. The vibration sensor according to claim 1, wherein the second housing has a connector portion, and the lead terminal member provided in the first member inside the connector portion. Vibration sensor that is guided.