JPH11287821A - Acceleration detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in mount position of a circuit board and make a structure simple and compact by securing together a plurality of circuit boards where a plurality of acceleration detection parts are separately mounted to one housing and directly fixing the circuit boards to a mount tool. SOLUTION: Three circuit boards 2 each having a semiconductor acceleration sensor (acceleration detection part) 1 mounted thereto are fixed together to one housing 23 in a state while the three circuit boards are mutually close to each other. The whole of the circuit boards 2 and housing 23 are covered with a metallic case 24 and a metallic lid 25 into a shield structure. With the metallic lid 25 being interposed, the housing 23 is directly fixed to a mount tool 12. Every three lead-through capacitors (nine in total) for resisting to waves are set for each circuit board 2 at an upper face of the metallic case 24. Moreover, a board base 28 is mounted at the side of the upper face of the metallic case 24. The accumulation of mount errors of many kinds is thus avoided, so that accuracy in mount position of the circuit boards 2 is improved. The number of parts is also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration detecting device such as a horizontal two-axis semiconductor accelerometer for a vehicle, and more particularly, to a highly accurate mounting to an object to be detected. The present invention relates to an acceleration detection device that can be downsized.

[0002]

2. Description of the Related Art FIGS. 8 to 11 show a conventional structure of an acceleration detecting device (horizontal two-axis semiconductor acceleration sensor unit) for detecting acceleration applied to a vehicle when the vehicle accelerates or decelerates or turns. FIG. 8 is a side sectional view of the apparatus (a sectional view taken along line CC in FIG. 9), FIG. 9 is a horizontal sectional view of the apparatus (a sectional view taken along line AA in FIG. 10), and FIG.
0 is a side sectional view of the apparatus (a sectional view taken along line BB in FIG. 9), and FIG. 11 is a view showing the internal structure of the sensor assembly.

In FIG. 11, reference numeral 1 denotes a semiconductor acceleration sensor, and reference numeral 2 denotes a circuit board on which a detection circuit and the like are mounted. The semiconductor acceleration sensor 1 is formed by etching a silicon semiconductor substrate to form a pendulum including a support portion, a weight portion, and a beam portion connecting the weight portion to the support portion. Is a known acceleration sensor element for electromagnetically or optically detecting a displacement to be converted into an electrical signal as a detected value of acceleration and outputting the signal. In this case, the semiconductor acceleration sensor 1 is mounted on a circuit board 2, and the circuit board 2 is fixed in a metal case 4 mounted on a housing 3. The metal case 4 is covered with a metal lid 5, whereby
A shield for shielding the circuit board 2 including the semiconductor acceleration sensor 1 from an external magnetic field is formed. The sensor assembly 10 is configured by one set of these components (the semiconductor acceleration sensor 1, the circuit board 2, the housing 3, the metal case 4, and the metal lid 5).

In FIG. 11, reference numeral 6 denotes a plurality of terminals provided on the housing 3 for power supply or signal of the circuit board 2. In this case, the connection terminals 6 are connected at their upper ends to predetermined circuit conductors of the circuit board 2 by rod-shaped conductors 7 provided in a state penetrating the metal case 4 in the lateral direction, and the lower ends thereof are connected to the housing. 3 protrudes from the lower surface side. The lower end of the connection terminal 6 protruding from the lower surface side of the housing 3 functions as a connection portion to a base substrate 11 described later. The acceleration detection device of the present example includes three of the above-described sensor assemblies 10 to detect acceleration in each direction.
As shown in FIGS. 8 to 10, these three sensor assemblies 10 are arranged and assembled in a predetermined direction on the upper surface side of one base substrate 11, and the base substrate 11 is further mounted on a mounting member made of resin or metal. 12 and is fixed.

[0005] A fixing base 12a is provided on the fixture 12, and the corners of the base substrate 11 are screwed onto the fixing base 12a, whereby the base substrate 11 is fixed. The mounting fixture 12 is provided with a plurality of mounting through holes 12b through which mounting screws and the like are inserted, and the mounting screws and the like are inserted through the mounting through holes 12b to the vehicle body. By fastening, the entire device is attached to the vehicle. Also,
The mounting case 12 includes a protective case 1 made of resin, metal, or the like.
The sensor case 3 is attached, and each sensor assembly 10 and the base substrate 11 are covered and protected by the protective case 13. In addition, each sensor assembly 1
0 are connected to predetermined terminals of a connector 15 disposed outside the outer case 13 by a circuit conductor of the base substrate 11 and a cable 14 extending from a side surface of the outer case 13. It is connected. The connector 15
Is connected to a vehicle controller or the like that receives and processes the acceleration detection signal by a cable (not shown).

[0006]

However, the conventional acceleration detecting device has the following problems. (1) The housing 3 on which the circuit board 2 on which the semiconductor acceleration sensor 1 is mounted is mounted on the mounting fixture 12 via the base substrate 11, and the mounting base 12 is provided with a fixing base 12 a for the base substrate 11. Was installed. As a result, the mounting structure is complicated and various mounting errors are accumulated.
The mounting posture (angle in the horizontal direction or the vertical direction) of the semiconductor acceleration sensor 1 varies from product to product, and it is difficult to achieve high mounting position accuracy of the semiconductor acceleration sensor 1 with respect to the vehicle. For this reason, there has been a problem that the characteristics of the output voltage, which is the acceleration detection signal, vary to some extent from product to product, and the detection accuracy and reliability of the acceleration sensor deteriorate.

In general, an acceleration sensor has directionality and should accurately detect acceleration in a predetermined direction. Therefore, if the acceleration sensor is not mounted in a proper posture, the detection accuracy is assured accordingly. It becomes difficult. In addition, in the case of the above-described semiconductor acceleration sensor and the like, the output voltage changes depending on the vertical mounting angle because it is affected by the gravitational acceleration. Further, when a plurality of acceleration sensors are provided to simultaneously detect multi-directional accelerations as in the above-described vehicle acceleration detecting device, if the mounting posture of the entire device is displaced, the direction to be detected by each acceleration sensor is changed. The detection sensitivity in the other direction is larger,
This is because acceleration in the original direction cannot be accurately detected.

(2) Further, the circuit boards 2 on which the respective semiconductor acceleration sensors 1 are mounted are assembled in separate housings 3 respectively, and a plurality of sensor assemblies 10 composed of the separate housings 3 are respectively mounted on the base board 11.
Further, since the base board 11 is attached to the fixture 12 with a complicated configuration, the number of parts is large, miniaturization is difficult, and the number of assembly steps is disadvantageous.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an acceleration detecting device which can be mounted on a detection target with high accuracy, and which can realize a simple and compact structure.

[0010]

According to a first aspect of the present invention, there is provided an acceleration detecting apparatus for detecting accelerations in at least two different directions; A mounting tool for mounting the acceleration detecting section to the detection target, wherein the plurality of acceleration detecting sections are mounted on separate circuit boards, respectively, and the plurality of circuit boards are fixed to one housing. The housing is directly fixed to the fixture.

Further, the acceleration detecting device according to claim 2 is
A positioning member for positioning and mounting the housing to the mounting tool is provided.

Further, the acceleration detecting device according to claim 3 is
A window for mounting the circuit board inside the housing is provided in the housing to avoid interference between the circuit board including the acceleration detection unit and the housing.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 7 are diagrams showing an example of a vehicle acceleration detection device (horizontal two-axis semiconductor acceleration sensor unit) to which the present invention is applied. Figure 1
2 is a side sectional view of the apparatus (a sectional view taken along line CC in FIG. 2), and FIG.
3 is a horizontal sectional view of the apparatus (sectional view taken along the line AA in FIG. 1), FIG. 3 is a view taken in the direction of the arrow G in FIG. 1, FIG. 4 is a side sectional view of the apparatus (BB sectional view in FIG. 2), and FIG. FIG. 6 is a horizontal sectional view of the apparatus (a sectional view taken along line DD in FIG. 1), FIG. 6 is a horizontal sectional view of the apparatus (a sectional view taken along line EE in FIG. 1), and FIG. The same elements as in the conventional example include:
The same reference numerals are given and duplicate description is omitted.

In the apparatus of this embodiment, as shown in FIG. 1 or FIG. 6, each circuit board 2 is collectively fixed to one housing 23, and the entire circuit board 2 and housing 23 are made of one metal. It is configured to be covered and shielded by a case 24 and a metal lid 25. And the housing 2
3, with the metal lid 25 interposed in this case,
It is directly fixed to the fixture 12. Further, a through-type capacitor 27 for radio wave protection is provided on the upper surface of the metal case 24.
Three are provided for each circuit board 2 (a total of nine), and one base board 28 is mounted on the upper surface side of the metal case 24. 2 and 3
In the drawings, reference numeral 14a denotes a cable fastener for fixing the cable 14 to the fixture 12.

Here, as shown in FIG. 7 (a), the housing 23 has a board arrangement space 3 for arranging and fixing the three circuit boards 2 at positions as close to each other as possible.
In this case, the semiconductor acceleration sensor 1 of the circuit board 2 which is provided in the board placement space 33 is provided inside (in FIG. 7B, the side facing in the direction orthogonal to the paper surface).
It is located at. An opening for avoiding interference with the circuit board 2 arranged in the board arrangement space 33 and the semiconductor acceleration sensor 1 mounted on the circuit board 2 arranged in the board arrangement space 33 is provided in a wall 34a of the housing 23 which separates the board arrangement spaces 32 and 33. Is formed. Thereby, the circuit board 2 arranged in the board arrangement space 33 can be arranged inside the housing 23, and the circuit board 2 arranged in the board arrangement space 32 can be arranged.
And the circuit board 2 arranged in the board arrangement space 33 can be arranged at a high density in a state of being closer to each other.

Positioning pins 36 for positioning the circuit board 2 and fixing it by heat welding, and a boss 37 for supporting the circuit board 2 are provided in each board arrangement space of the housing 23, respectively. 1, each circuit board 2 can be easily fixed in a predetermined posture. In addition, connection terminals 38 for power supply or signal of the circuit board 2 arranged in each board arrangement space are respectively provided on the walls 34a and 34b which partition each board arrangement space of the housing 23 with respect to each board arrangement space. Three are provided each. Note that these connection terminals 3
Reference numeral 8 denotes a rod-shaped conductor 39 which is provided in each board arrangement space so as to protrude horizontally, and the lower end of which is a circuit board 2.
, And an upper end thereof protrudes from the upper surface of the housing 23. The upper end of the terminal 38 projecting from the upper surface of the housing 23 functions as one electrode of the feedthrough capacitor 27 provided on the upper surface of the metal case 24.

Further, a plurality of positioning pins 40 for positioning and mounting the metal case 24 and the base substrate 28 are provided on the upper surface side of the housing 23, and the housing 23 is provided with
A plurality of positioning pins 41 and locking projections 42 for positioning and attaching to the position 2 are provided. As shown in FIG. 1 or FIG. 3, the positioning pin 41 and the locking projection 42 penetrate through the metal lid 25 and the fixture 12, and are engaged in a state of protruding from the rear side of the attachment surface of the fixture 12. Or, it is configured to be locked.

The connection terminal 38 of each circuit board 2 functions as one electrode of the feedthrough capacitor 27 as described above, and is connected to a predetermined circuit conductor of the base board 28 via the feedthrough capacitor 27. Further, it is connected to the cable 14 of the connector 15 via a circuit conductor of the base substrate 28 and the like. That is, the predetermined circuit conductors to be electrically connected to an external controller or the like in each circuit board 2 include the rod-shaped conductor 39, the connection terminal 38,
It is connected to predetermined terminals of the connector 15 via the feedthrough capacitor 27, circuit conductors or terminals of the base substrate 28, and cables 14.

The area where the feedthrough capacitor 27 is mounted on the upper surface of the metal case 24 is formed by a recess 24 a one step lower in accordance with the height of the feedthrough capacitor 27.
Accordingly, the base substrate 28 can be directly placed and fixed on the upper surface of the metal case 24 without interposing a spacer between the lower surface of the base substrate 28 and the upper surface of the metal case 24. , Base substrate 28 and feedthrough capacitor 2
7 can be directly connected.

With the structure of the acceleration detecting device of the present embodiment described above, the following various effects can be obtained. (1) Since the housing 23 to which the circuit board 2 on which the semiconductor acceleration sensor 1 (acceleration detection unit) is mounted is fixed to the fixture 12 directly, accumulation of various types of mounting errors can be avoided, and the circuit The mounting position accuracy of the substrate 2 (particularly, the positioning accuracy of the vertical mounting angle) can be remarkably improved. For this reason, the degree to which the characteristics of the output voltage, which is the acceleration detection signal, varies from product to product can be reduced, and the detection accuracy and reliability of the acceleration sensor can be greatly improved. In particular, in this example, the housing 23 is attached to the fixture 12.
Since the positioning pins 41 (positioning members) for positioning and mounting the circuit board 2 are provided, the mounting position accuracy of the circuit board 2 (particularly, the positioning accuracy of the horizontal mounting angle) is further improved, and the original direction due to the positional deviation is increased. The problem that the acceleration cannot be detected accurately can be avoided with higher reliability.

(2) Since all of the plurality of circuit boards 2 are fixed to one housing 23 and are directly attached to the fixture 12, the number of parts is smaller than in the conventional case where a housing is provided for each circuit board. The number of points (at least the number of housings) can be reduced. In particular, when the circuit board is covered with a metal member and shielded, if the entire circuit board and one housing 23 are covered with a set of a metal case 24 and a metal lid 25 as in this example, these shields may be used. It is possible to further reduce the number of components as compared with the related art in which a metal member for each circuit board is provided. That is, the number of housings, metal cases, and metal lids can be reduced from the conventional three to one. Further, in this embodiment, the base substrate 28
Since it is not necessary to interpose a spacer between the metal case 24 and the metal case 24, the number of parts can be reduced in this respect as well.

(3) Since the housing, which was conventionally a separate member for each circuit board, is integrated, the entire housing can be reduced in size, and each circuit board can be easily arranged at high density. Further, as described above, the number of components is reduced, and a portion such as the conventional base board fixing base 12a is not required, so that the entire apparatus can be significantly reduced in size. In particular, in the case of this example, since the window 35 for avoiding interference with the circuit board 2 is provided in the housing 23, the circuit board 2 can be arranged more inside, and the circuit board 2 can be arranged at a higher density. It is possible. Incidentally, according to the estimates by the inventors, it has been found that the structure of the present example can reduce the volume of the entire device to about 70% of the conventional device.

(4) Also, as described above, the simple structure with the reduced number of parts has the effect of reducing the overall number of assembling steps. In particular, in the case of this example, a positioning pin 41 for positioning the housing 23 with respect to the fixture 12 and a positioning pin 40 for positioning and mounting the metal case 24 and the base substrate 28 on the housing 23 are provided. In addition, the positioning of these components is extremely easy, and in this respect, the number of steps for assembling can be reduced.

[0024]

According to the acceleration detecting device of the present invention, a plurality of acceleration detecting sections are mounted on different circuit boards, respectively, and the plurality of circuit boards are fixed to one housing, and the housing is directly fixed to the mounting fixture. . Thus, accumulation of various types of mounting errors can be avoided, and the mounting position accuracy of the circuit board can be remarkably improved. For this reason, the degree to which the characteristics of the output voltage, which is the acceleration detection signal, varies from product to product can be reduced, and the detection accuracy and reliability of the acceleration sensor can be greatly improved. In particular, in the acceleration detecting device according to the second aspect, since the positioning member for positioning and mounting the housing on the mounting member is provided, the mounting position accuracy of the circuit board is further improved, and the acceleration in the original direction due to the displacement is increased. Can be avoided with higher reliability.

Further, since all of the plurality of circuit boards are fixed to one housing and are directly attached to the fixture, the number of parts (at least the number of housings) is smaller than in the conventional case where the housing is provided for each circuit board. Number) can be reduced. In particular, when the circuit board is covered with a metal member and shielded, if the whole of each circuit board and the housing is covered with a set of a metal case and a metal lid as in the above-described embodiment, these shielding metal members can be used. Can be further reduced as compared with the related art in which is provided for each circuit board. That is, the number of housings, metal cases, and metal lids can be reduced from the conventional three to one.

In addition, since the housing, which was conventionally a separate member for each circuit board, is integrated, the size of the entire housing can be reduced, and each circuit board can be easily arranged with high density. Further, as described above, the number of components is reduced, and a portion such as the conventional base board fixing base 12a (shown in FIG. 8) is not required, so that the entire apparatus can be significantly reduced in size. In particular, in the acceleration detecting device according to the third aspect, since the window that avoids interference with the circuit board is provided in the housing, the circuit board can be arranged more inside, and the circuit board can be arranged at a higher density. Further miniaturization can be realized.

Further, the simple structure with the reduced number of parts as described above has the effect of reducing the number of assembling steps as a whole. In particular, in the case of the second aspect, since the positioning member for positioning the housing with respect to the fixture is provided, the positioning is extremely easy, and also in this respect, the number of steps for assembling can be reduced. .

[Brief description of the drawings]

FIG. 1 is a side sectional view of an acceleration detection device.

FIG. 2 is a horizontal sectional view of the acceleration detection device.

FIG. 3 is a view taken in the direction of arrow G in FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a sectional view taken along line DD of FIG. 1;

FIG. 6 is a sectional view taken along the line EE of FIG. 1;

FIG. 7 is a view showing a housing.

FIG. 8 is a side sectional view of a conventional acceleration detection device.

FIG. 9 is a horizontal sectional view of a conventional acceleration detecting device.

FIG. 10 is a sectional view taken along the line BB of FIG. 9;

FIG. 11 is a view showing a conventional sensor assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor acceleration sensor (acceleration detection part) 2 Circuit board 12 Mounting fixture 23 Housing 24 Metal case 25 Metal lid 28 Base substrate 35 Window 41 Positioning pin (positioning member) 24a Recess

Claims (3)

[Claims] An acceleration detection device comprising: a plurality of acceleration detection units provided for detecting accelerations in at least two different directions; and a fixture for mounting the plurality of acceleration detection units to a detection target. The acceleration detection device according to claim 1, wherein the plurality of acceleration detection units are mounted on different circuit boards, respectively, and the plurality of circuit boards are fixed to one housing, and the housing is directly fixed to the attachment. 2. An acceleration detecting device according to claim 1, further comprising a positioning member for positioning and mounting said housing to said mounting tool. 3. The housing is provided with a window for mounting the circuit board inside the housing so as to avoid interference between the circuit board including the acceleration detection section and the housing. The acceleration detection device according to claim 1.