JPH09126876A - Knocking sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a knocking sensor by providing a displacing section which is displaced when a member to be measured makes knocking vibrations, a weight section which is adjusted so that the displacing section can make resonant vibrations when the member makes knocking vibrations, a detecting section which generates the signal corresponding to the displacement of the displacing section, and a signal processing section. SOLUTION: A diaphragm section 14 is displaced when a member to be measured makes knocking vibrations. Since a weight section 15 is integrally displaced together with the diaphragm section 14 and the natural vibration of a knocking sensor 10 varies depending upon the magnitude of the weight section 15, the sensor 10 is constituted to have the characteristic frequency corresponding to the knocking vibrations by adjusting the magnitude of the section 15 at the machining time. The voltage fluctuation generated in a resistor section 16 is transmitted to a knocking judging circuit 17 as a knocking detecting signal. The circuit 17 judges the occurrence of knocking based on the signal. Therefore, the sensor 10 can be constituted so that the sensor 10 can detect the knocking vibrations without using any PZT piezoelectric element and, at the same time, the size of the sensor 10 can be reduced by uniting the circuit 17 to a substrate 12 in one body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock sensor, and more particularly to a knock sensor used to detect knocking generated in an engine.

[0002]

2. Description of the Related Art In general, an internal combustion engine (engine) which is electronically controlled is provided with a knock sensor for detecting occurrence of knocking. As a conventional knock sensor, for example, one disclosed in Japanese Patent Laid-Open No. 4-77627 is known. FIG. 9 shows the knock sensor disclosed in the publication.

As shown in FIG. 1, the knock sensor includes a metal base 2, a diaphragm 5, and a PZT (piezo-transducer) piezoelectric element 6 in a housing 1 fixed to an engine.
Etc. are internally provided, and a connector 3 having a terminal 4 therein is disposed on the upper part thereof. The piezoelectric element 6 is attached to the diaphragm 5, and the diaphragm 5 is fixed to the metal base 2. Further, the piezoelectric element 6 is electrically connected to the terminal 4 by the wire 7, so that the signal output from the piezoelectric element 6 is extracted to the outside of the housing 1.

In the knock sensor having the above structure, when knocking occurs in the engine and knock vibration is transmitted to the housing 1, the diaphragm 5 vibrates and deforms in response to the knock vibration. Since the piezoelectric element 6 is attached to the vibrating plate 5 as described above, the piezoelectric element 6 is also deformed as the vibrating plate 5 is deformed, and electric charges are generated on the front and back surfaces thereof.

A change in electric charge generated in the piezoelectric element 6 is extracted as a knock detection signal by the terminal 4 to the connector 3. A knocking determination circuit (not shown), which is separate from the knock sensor, is connected to the connector 3. Therefore, the knock detection signal output from the terminal 4 is taken into the knock determination circuit, and the presence or absence of knock is determined here.

[0006]

As described above, the conventional knock sensor is constructed so as to detect the occurrence of knocking by vibrating the diaphragm 5 by the resonant vibration of the knocking vibration generated in the engine. Therefore, the natural frequency of the diaphragm 5 provided with the piezoelectric element 6 is set to correspond to the frequency of knocking vibration.

By the way, in recent years, from the viewpoint of weight reduction of vehicles,
Engines and their peripheral devices and devices are being downsized. Along with this, there has been a demand for miniaturization of the knock sensor arranged in the engine. However,
In the knock sensor of the conventional configuration shown in FIG. 9, it is necessary to downsize the diaphragm 5 and the piezoelectric element 6 in order to downsize it. However, in order to generate the resonance vibration as described above, it is necessary to make the natural frequency of the diaphragm 5 having the piezoelectric element 6 correspond to the frequency of knocking vibration.

Therefore, in order to reduce the size of the diaphragm 5 and the piezoelectric element 6 without changing the resonance frequency (specifically, to reduce the outer diameter), the thickness of the diaphragm 5 and the piezoelectric element 6 should be reduced. It becomes necessary to make it thinner. However, when the PZT piezoelectric element 6 is thinned, it is easily cracked, so that there is a problem that it is difficult to downsize the knock sensor.

In addition, since the knock sensor and the knock determination circuit are separately configured in the conventional configuration, two devices are required as the device for detecting the knock, which also increases the size of the knock detection device. There was a problem. On the other hand, if the knock sensor is large in shape as described above, the mounting position on the engine is limited. Although it is desirable to install the knock sensor at a position near the cylinder of the engine where knocking occurs, various accessories are installed on the side of the engine. The mounting position of is limited. For this reason, in the conventional knock sensor, the knock sensor cannot be disposed at the position most suitable for knocking detection, and thus there is a problem that the knocking detection accuracy decreases.

The present invention has been made in view of the above points, and has a configuration capable of detecting knocking vibrations without using a PZT piezoelectric element, and by integrating a knocking determination circuit with a sensor, The purpose is to reduce the size and improve the detection accuracy.

[0011]

In order to solve the above problems, according to the present invention, in a knock sensor for detecting knock vibration generated in a member to be measured, a silicon semiconductor substrate provided on a pedestal and the silicon semiconductor substrate are provided. And a displacement portion that is integrally formed on the displacement portion and that is displaced in response to the knock vibration, and that is provided in the displacement portion and that the displacement portion is adjusted to resonate by the knock vibration generated in the measured member. A weight portion, a detection portion which is formed in the displacement portion by a doping technique, generates a signal corresponding to the displacement of the displacement portion, and is integrally formed in the silicon semiconductor substrate, and is generated by the resistance portion. A signal processing circuit section for processing a signal is provided.

The above-mentioned means operates as follows. Since the silicon semiconductor substrate has a small hysteresis when displaced, it has ideal properties as an elastic body. Therefore, by integrally forming the displacement portion that displaces in response to knock vibration on the silicon semiconductor substrate, it is possible to realize the displacement portion having a good elastic return property.

Further, in the knock sensor for detecting the knock vibration of the member to be measured, it is necessary to make the displacement portion resonate with the knock vibration. In the present invention, by adjusting the natural frequency of the displacement portion and the weight portion by adjusting the weight portion (for example, adjusting the weight), the displacement portion and the weight portion resonate due to the knock vibration generated in the measured member. It is configured to vibrate around the circumference.

Further, since the detecting portion is formed in the displacement portion by the doping technique, the detecting portion is integrated with the silicon semiconductor substrate. Therefore, even if the shapes of the displacement portion and the weight portion are changed in order to make the natural frequency correspond to the frequency of knock vibration, the mechanical strength of the detection portion is reduced unlike the conventional configuration using the PZT piezoelectric element. There is no such thing. Therefore, the shapes of the displacement portion and the weight portion can be set regardless of the detection portion, and the predetermined natural frequency can be set while reducing the size of the displacement portion and the weight portion.

Furthermore, by integrally forming the signal processing circuit unit for processing the signal generated by the detection unit on the silicon semiconductor substrate, it is not necessary to separately provide the signal processing circuit unit, and the entire apparatus for performing knock detection is provided. Can be miniaturized.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a knock sensor 10 which is a first embodiment of the present invention. FIG. 1 is a plan view of the knock sensor 10, and FIG. 2 is A-A in FIG.
It is sectional drawing which follows a line.

As shown in each figure, knock sensor 10
Has a silicon pedestal 11 (shown in FIG. 2) and a silicon semiconductor substrate 12 (hereinafter, simply referred to as a substrate). The silicon pedestal 11 and the substrate 12 are housed in a housing (not shown) and then a cylinder block of the engine. It is attached to and performs knocking detection processing.

The silicon pedestal 11 is a flat pedestal,
The substrate 12 is attached to the upper portion of the silicon pedestal 11. The substrate 12 is roughly composed of a leg portion 13, a diaphragm portion (displacement portion) 14, a weight portion 15, and a resistance portion (detection portion) 1.
6, and knocking determination circuit unit (signal processing circuit unit) 17
And the like. These constituent parts 13 to 17 are
It is integrally formed on the substrate 12 by using a micromachining technique and a doping technique. Below, each component 1
Each of 3 to 17 will be described.

The leg portion 13, the diaphragm portion 14, and the weight portion 15 are formed by anisotropically etching the substrate 12. By attaching the leg portion 13 to the silicon pedestal 11, the diaphragm portion 14 and the weight portion 1 are attached.
The function of supporting 5 is achieved. Further, the leg portion 13 is attached to the silicon pedestal 11, so that the void portion 18 is formed between the silicon pedestal 11 and the substrate 12.

The diaphragm portion 14 is made thinner than the other portions, and is constructed so that it can be displaced in response to knock vibration generated in the engine. Further, since silicon, which is the material of the substrate 12, is a covalent bond crystal, the diaphragm portion 14 has a small hysteresis when displaced in response to knock vibration and has an ideal property as an elastic body. Therefore, by integrally forming the diaphragm portion 14 on the substrate 12 made of silicon, it is possible to realize a diaphragm having a good elastic return characteristic.

The weight portion 15 is integrally formed at a substantially central position of the diaphragm portion 14, and has a rectangular shape in this embodiment. The weight portion 15 is integrally displaced by the displacement of the diaphragm portion 14. Therefore,
The natural frequency of knock sensor 10 is determined by the thickness and width of diaphragm portion 14 and the size (shape and weight) of weight portion 15.

On the other hand, the knock vibration of the engine varies depending on various requirements such as the size and compression ratio of the engine. Therefore, in order for the knock sensor 10 to have a natural frequency corresponding to the knock vibration generated in the engine, It is necessary to adjust the thickness and width of the diaphragm portion 14 and the size of the weight portion 15. However, it is difficult to arbitrarily change the thickness of the diaphragm portion 14 from the aspect of controllability of etching processing and the aspect of maintaining mechanical strength, and the width also changes because the overall size and positional relationship change. Is difficult to do.

On the other hand, since the weight portion 15 has a shape projecting downward toward the gap portion 18 at a substantially central position of the diaphragm portion 14, the shape and weight can be changed more easily than the diaphragm portion 14. be able to. For this reason,
In this embodiment, by adjusting the size of the weight portion 15 when the weight portion 15 is processed, the weight portion 15 has a natural frequency corresponding to the knock vibration of the engine to which the knock sensor 10 is attached.

As a specific method for adjusting the size of the weight portion 15, for example, when the substrate 12 is subjected to an etching process, the size of the mask to be provided in a portion which is not etched is appropriately set. Things can be considered. Resistor 16
Are formed on the upper surface of the diaphragm portion 14 using a doping technique. Specifically, for example, when an n-type silicon substrate is used as the substrate 12, p is formed by using a doping technique such as an impurity diffusion technique or an ion implantation technique.
The resistance portion 16 is formed by forming the mold region.

The resistance portion 16 generates a resistance change corresponding to the displacement generated in the diaphragm portion 14 due to the piezo resistance effect. Therefore, the displacement of the diaphragm portion 14, that is, the occurrence of knocking can be detected by detecting the voltage drop generated in the resistor portion 16. This resistance part 1
The voltage change occurring at 6 is transmitted as a knock detection signal to a knocking determination circuit unit 17 described later.

Further, in this embodiment, the resistor portion 16 is formed in a wavy pattern so as to be formed over the entire upper surface of the diaphragm portion 14, so that the displacement of the diaphragm portion 14 can be reliably detected. There is.
As described above, since the resistance portion 16 is formed on the diaphragm portion 14 by using the doping technique, the resistance portion 16 is integrated with the substrate 12. Therefore, even if the size of the weight portion 15 is changed in order to make the natural frequency correspond to the frequency of knock vibration, unlike the conventional knock sensor using the PZT piezoelectric element 6 shown in FIG. The mechanical strength of itself does not decrease.

Therefore, regardless of the resistance portion 16, the weight portion 1
The size of 5 can be set, and the diaphragm portion 14
In addition, it is possible to set the natural frequency corresponding to the frequency of knock vibration while reducing the size of the weight portion 15.
On the other hand, the knocking determination circuit portion 17 is formed integrally with the substrate 12 (in FIG. 1, the formation region of the knocking determination circuit portion 17 is shown by a chain double-dashed line). Further, the formation position thereof is selected at the outer peripheral position of the diaphragm portion 14, that is, the upper position of the leg portion 13. The knocking determination circuit unit 17 has a function of receiving the knock detection signal output from the resistance unit 16 and determining whether knocking occurs in the engine based on the knock detection signal.

FIG. 3 shows the circuit configuration of the knocking determination circuit section 17. As shown in the figure, the knocking determination circuit unit 17 includes a filter circuit 19 and a peak value detection circuit 2.
0, a comparison reference level calculation circuit 21, a comparator 22 and the like. The knock detection signal output from the resistance unit 16 is supplied to the filter circuit 19 to remove unnecessary signals, and then supplied to the peak value detection circuit 20 and the comparison reference level calculation circuit 21, respectively. The peak value detection circuit 20 calculates the peak value of the knock detection signal and
The comparison reference level calculation circuit 21 calculates a comparison reference level (knocking determination voltage) serving as a knocking determination reference.

The peak value calculated by the peak value detection circuit 20 and the comparison reference level calculated by the comparison reference level calculation circuit 21 are supplied to the comparator 22, and when the peak value is larger than the comparison reference level, the comparator Two
A knocking determination signal is output to the output side of 2.

Knocking determination circuit section 1 having the above configuration
7 is formed integrally with the substrate 12 using a semiconductor manufacturing technique. Therefore, there is no need to provide a knocking determination circuit that performs knocking determination processing separately from the knock sensor 10, and the overall size of the device that performs knocking determination can be reduced.

Further, the knocking determination circuit section 17 includes the leg section 1.
Since it is formed on the upper portion of 3, the diaphragm portion 14 and the weight portion 15 are not displaced even if they are displaced. Therefore, even if the knocking determination circuit portion 17 is formed integrally with the substrate 12, the displacement of the diaphragm portion 14 and the weight portion 15 does not change the characteristics of the knocking determination circuit portion 17, and stable knocking determination is achieved. Processing can be performed.

As described above, the knock sensor 10 according to this embodiment has a structure in which knocking vibration can be detected without using a PZT piezoelectric element, and the knocking determination circuit portion 17 is integrated with the substrate 12 to reduce the size. Can be realized. Specifically, in the conventional knock sensor shown in FIG. 9, the outer diameter is 20 to 30 mm and the height is 40 to 40 mm.
The knock sensor 10 according to the present embodiment has an outer diameter of 10 to 20 mm and a height of 30 to 80 mm.
The size can be reduced to about 50 mm.

Since the knock sensor 10 can be miniaturized in this manner, the degree of freedom of the mounting position can be improved when the knock sensor 10 is mounted on the engine.
The knock sensor 10 can be attached at a position most suitable for detecting knocking. Therefore, knock vibration can be reliably detected, and therefore, knocking detection accuracy of knock sensor 10 can be improved.

Since the resistance portion 16 described above is a piezoresistor, the piezoresistance coefficient has high temperature dependence, but temperature compensation can be easily performed by forming the resistance portion 16 in a bridge circuit configuration. Next, a second embodiment of the present invention will be described.

FIGS. 4 and 5 show a knock sensor 30 which is a second embodiment of the present invention. 4 shows the knock sensor 3
5 is a plan view of No. 0, and FIG. 5 is a sectional view taken along line BB in FIG. 4 and 5, the same components as those of the knock sensor 10 according to the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

In the knock sensor 30 according to the present embodiment, the shape of the weight portion 31 and the outer shape of the diaphragm portion 32 are formed into a perfect circle when seen in a plan view, and a fine adjustment weight 33 is provided on the upper portion of the weight portion 31. It is characterized by that. As described above, the natural frequency of the knock sensor 30 is determined by the shapes and weights of the weight portion 31 and the diaphragm portion 32. At this time, the natural frequency can be stabilized by making the shape of the weight portion 31 and the outer shape of the diaphragm portion 32 into a perfect circular shape that is symmetrical with respect to the center point of the substrate 12 as in the present embodiment. it can. As a result, the accuracy of knock determination of knock sensor 30 can be improved.

The fine adjustment weight 33 has a weight portion 31.
Is formed on the upper part of the substrate using, for example, a thin film forming technique. Specifically, the fine adjustment weight 33 is formed by depositing an aluminum film using a vapor deposition method. Since the fine adjustment weight 33 is formed in a state of being exposed at the upper portion of the weight portion 31, it is possible to change the weight and shape of the fine adjustment weight 33 by etching or laser tremming after the knock sensor 30 is formed.

Since the weight portion 31 is formed by anisotropically etching the substrate 12 as described above, its forming accuracy is not so high. Therefore, the fine adjustment weight 33 is provided as described above, and by performing etching or laser tremming on the fine adjustment weight 33, the weight 33 is molded to correspond to the frequency of the knock vibration, so that the natural frequency after the knock sensor 30 is formed. Can be adjusted. Therefore, the natural frequency corresponding to the knock vibration to be detected can be accurately realized, and the knock determination accuracy can be improved.

Further, the knock sensor 30 according to the present embodiment.
Is attached so that the leg portion 13 and the silicon pedestal 11 are in an airtight state. That is, in the knock sensor 30, the gap portion 18 is in a sealed state. With this configuration, the gap portion 18 can function as an air damper, and the weight portion 31 and the diaphragm portion 32 can be used.
Can be prevented from excessive displacement. Therefore, even if a disturbance (large vibration) is applied, the knock sensor 30
It is possible to reliably prevent the occurrence of damage.

FIG. 6 shows a circuit configuration of a knocking determination circuit portion 34 formed integrally with the substrate 12 of the knock sensor 30. As shown in the figure, the knocking determination circuit unit 34 includes a bandpass filter 35, a rectifier circuit 36, an amplifier circuit 37, a comparator 38, and the like.

A constant current source 39 (or a constant voltage source) is connected to the resistor section 16. The knock detection signal output from the resistance unit 16 is band-limited by the bandpass filter 35 and then supplied to the rectifier circuit 36. Rectifier circuit 3
In 6, the peak value of the knock detection signal is calculated, and the peak value is amplified by the amplifier circuit 37 and then supplied to the comparator 38. Further, a reference voltage serving as a reference for knocking determination is applied to the comparator 38,
The comparator 22 outputs a knocking determination signal to its output side when the peak value is larger than the reference voltage.

Next, a knock sensor 4 which is another example of the configuration.
0 will be described. FIG. 7 is a sectional view of the knock sensor 40. In the knock sensors 10 and 30 according to the first and second embodiments, the diaphragm portions 14 and 32, the weight portions 15 and 31, and the resistance portion 16 are provided on the substrate 12 made of a semiconductor material.
Etc. are integrally formed, and the resistance portion 16 which is a piezoresistor is used as a so-called semiconductor knock sensor that determines the occurrence of knocking by utilizing the fact that the resistance value changes due to the displacement of the diaphragm portions 14 and 32. It was On the other hand, the knock sensor 40 is configured to detect and determine the occurrence of knocking as a change in capacitance. Hereinafter, the configuration of knock sensor 40 will be described.

The knock sensor 40 roughly includes a lower housing 41, an upper housing 42, a semiconductor chip 43,
The external connection terminals 44 and 45, the chip side electrode 46, the diaphragm 47, and the like are included. The lower housing 41 and the upper housing 42 are formed of, for example, a ceramic or metal material, and are integrally formed by caulking the caulking portion 48 formed on the lower housing 41 to the upper housing 42. Further, the lower housing 41 and the upper housing 42 both have cavity portions 41a and 42a formed therein, and a gap portion 49 is formed inside when the housings 41 and 42 are combined.
Is formed.

In the lower housing 41, a pair of external connection terminals 44 are planted on the bottom with an insulator interposed, and a semiconductor chip 43 is arranged in the cavity 41a. The outer end of the external connection terminal 44 projects downward from the lower housing 41, and the inner end of the external connection terminal 44 is exposed in the cavity 41a, so that the semiconductor chip 43 and the wire 5 are exposed.
It is electrically connected using 0. Further, the upper housing 42 is arranged above the upper housing 42, and the mounting portion 52 is mounted on the engine block 53. By mounting the mounting portion 52 on the engine block 53, the knock sensor 40 is mounted on the engine.

The semiconductor chip 43 is a chip in which a knocking determination circuit portion 51, which will be described later, is formed into a circuit, and a chip side electrode 46 is formed on the upper surface by an aluminum vapor deposition film. The chip side electrode 46 constitutes one electrode (fixed electrode) of the capacitor.

The vibrating plate 47 is made of a conductive metal and is arranged at the boundary between the lower housing 41 and the upper housing 42. Specifically, the diaphragm 47 is fixed while being sandwiched between the lower housing 41 and the upper housing 42. The vibrating plate 47 constitutes the other electrode (lower electrode) of the capacitor and is grounded.

Further, the diaphragm 47 is constructed to have a natural frequency corresponding to the knock vibration of the engine to which the knock sensor 40 is attached. That is, the vibration plate 47 is set to a size that causes resonance vibration when knock vibration is applied. When the vibration plate 47 vibrates by applying the knock vibration in this way, the electrostatic capacitance between the vibration plate 47 and the chip-side electrode 46 arranged oppositely changes.

Therefore, the constant voltage source 54 is applied to the chip side electrode 46.
By connecting (see FIG. 8), a current change corresponding to the vibration of the diaphragm 47 is generated in the chip side electrode 46 (this current change is referred to as a knock detection signal). Therefore,
The occurrence of knocking can be detected by measuring the frequency of this knock detection signal.

Focusing on the structure of the diaphragm 47, the PZT piezoelectric element 6 is attached to the diaphragm 5 in the conventional knock sensor shown in FIG.
However, the diaphragm 47 is not provided with other components such as a PZT piezoelectric element. Therefore, when adjusting the natural frequency of the diaphragm 47, it is possible to set the size of the diaphragm 47 regardless of other constituent elements, reduce the thickness of the diaphragm 47, and reduce the thickness of the diaphragm 47. The outer diameter of can be reduced. As a result, the knock sensor 40 can be downsized and the natural frequency corresponding to the frequency of knock vibration can be set.

In addition, in each of the above-described embodiments, a part of the substrate 12 made of a semiconductor material resonates and vibrates, whereas in this embodiment, the diaphragm 47 made of a conductive metal resonates and vibrates. It is said that. The mechanical strength of the diaphragm 47 made of a conductive metal is the same as that of the substrate 12 made of a semiconductor material.
Stronger. Therefore, even if a large external force is applied, the vibration plate 47 is not damaged, and the reliability of the knock sensor 40 can be improved.

FIG. 8 shows the circuit configuration of the knocking determination circuit section 51 mounted on the semiconductor chip 43.
As shown in the figure, the knocking determination circuit unit 51 includes a buffer 54, a bandpass filter 55, a rectifier circuit 56,
The amplifier circuit 57 and the comparator 58 are included.

Chip-side electrode 46 that constitutes a capacitor
Is connected to a constant voltage source 59 via a resistor R. The knock detection signal output from the chip-side electrode 46 due to knock vibration is band-limited by the bandpass filter 55 via the buffer 54, and then supplied to the rectifier circuit 56. The rectifier circuit 56 calculates the peak value of the knock detection signal, and the peak value is amplified by the amplifier circuit 57 and then supplied to the comparator 58. A reference voltage serving as a reference for knocking determination is applied to the comparator 58, and the comparator 58 outputs a knocking determination signal to its output side when the peak value is larger than the reference voltage.

Knocking determination circuit section 5 having the above configuration
1 is formed on the semiconductor chip 43 by using a semiconductor manufacturing technique. The semiconductor chip 43 is arranged in the lower housing 41. Therefore, it is not necessary to provide a knocking determination circuit for performing knocking determination processing separately from the knock sensor 40, and this can also reduce the size.

[0054]

As described above, according to the present invention, the knock sensor can be downsized. Further, due to the miniaturization of the knock sensor, the knock sensor can be attached to the engine with a certain degree of freedom. For this reason, it becomes possible to dispose the knock sensor at the optimum position for detecting knocking, and it is possible to improve the knocking determination accuracy.

[Brief description of the drawings]

FIG. 1 is a plan view of a knock sensor that is a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a circuit configuration diagram of a knocking determination circuit unit arranged in the knock sensor according to the first embodiment.

FIG. 4 is a plan view of a knock sensor that is a second embodiment of the present invention.

5 is a cross-sectional view taken along the line BB in FIG.

FIG. 6 is a circuit configuration diagram of a knocking determination circuit unit arranged in a knock sensor according to a second embodiment.

FIG. 7 is a cross-sectional view of a knock sensor that is another configuration example.

8 is a circuit configuration diagram of a knocking determination circuit unit arranged in the knock sensor shown in FIG.

FIG. 9 is a cross-sectional view showing an example of a conventional knock sensor.

[Explanation of symbols]

 10,30,40 Knock sensor 11 Silicon pedestal 12 Substrate 13 Leg part 14,32 Diaphragm part 15,31 Weight part 16 Resistor part 17,34,51 Knocking judgment circuit 18,49 Gap part 33 Fine adjustment weight 41 Lower housing 42 Upper part Housing 43 Semiconductor chip 46 Chip side electrode 47 Vibration plate 51 Knocking determination circuit section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01M 15/00 G01M 15/00 A H04R 17/10 H04R 17/10 Z

Claims (1)

[Claims] 1. A knock sensor for detecting knock vibration generated in a member to be measured, which is formed integrally with a silicon semiconductor substrate arranged on a pedestal and is adapted to cope with the knock vibration. The displacement part, which is displaced by the displacement part, and the weight part which is provided in the displacement part and which is adjusted so that the displacement part resonates and vibrates due to knock vibration generated in the member to be measured, and the displacement part is formed by a doping technique. A detection unit that generates a signal corresponding to the displacement of the displacement unit; and a signal processing circuit unit that is integrally formed on the silicon semiconductor substrate and that processes the signal generated by the detection unit. And knock sensor.