JP2016070764A - Physical amount sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliable sensor generating little variation in sensor output by suppressing or reducing deformation in entire module.SOLUTION: The high-reliable sensor includes: a circuit board which is mounted with a sensor for detecting physical amount; and a housing 3 which includes a case storing the circuit board and a flange 5 for fixing external unit. The width t2 of the flange which is in contact with the case is 0.8 or more with respect to the width t1 of the case.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sensor device, and more particularly to a physical quantity sensor device that detects physical quantities such as acceleration and angular velocity.

  In recent years, sensor devices that detect various physical quantities have been used in automobiles, agricultural machines, construction machines, and the like in order to improve running stability control, safety, and workability. In automobiles, applications such as acceleration sensors and angular velocity sensors are expanding for controlling devices (for example, airbags) for preventing skidding and improving passenger safety. In addition, when the sensor device is applied to an automobile, it is assumed that the sensor device is mounted in an engine room. Therefore, it is necessary to withstand a severe environment such as a heat change and mechanical vibration. Agricultural machinery is used for harsh environments like automobiles, as it is used for attitude control of vehicle bodies and for horizontal control of accessories used for various farming applications.

  A physical quantity detection sensor mounted on a sensor device uses silicon (Si) micro processing technology (MEMS: Micro Electro Mechanical Systems) for the purpose of miniaturization, multi-function / combination, and mass productivity improvement. Means are becoming mainstream. A fine comb-like tooth structure of silicone is formed by a fine processing technique, and physical quantities such as acceleration and angular velocity are detected by converting a minute displacement of the comb-like structure into an electric signal.

  Such a physical quantity detection sensor is used in a state of being mounted on a circuit board together with other electronic components, and is housed in a case forming a housing and modularized. In addition, a connector for inputting and outputting electrical signals between the sensor mounted on the circuit board and the outside, and a flange and a cover for fixing the housing to an external device and the like form the housing together with the case.

  Since the physical quantity detection sensor described above uses minute displacement as a detection means, when vibration or impact is applied from the outside of the modular sensor device, the displacement is generated in the fine comb tooth structure and no inertial force is applied. But output occurs. The sensor output resulting from this vibration or impact causes an error in the physical quantity output that should be detected by the sensor device.

  Therefore, in a sensor using a silicon microfabrication technique, it is important to have a mounting structure in which an external force such as vibration or impact is not applied to or suppressed in the physical quantity detection unit.

  As a structure for suppressing or preventing vibration of an electronic device in which an electronic component or the like is housed in a housing and modularized, for example, one described in Patent Document 1 is known.

  In Patent Document 1, the electronic device module is configured to be attached to an external device via rubber so as to block or reduce vibrations transmitted through the attachment portion, and at least a part of the housing is made of a damping material. Alternatively, it is disclosed that the vibration of the housing or the case itself is reduced by forming the electronic component with a resin containing rubber in the case for housing the electronic component.

Japanese Patent Application Laid-Open No. 2004-249883

  However, in Patent Document 1, a modularized housing is fixed to an external device by fixing an attachment piece attached to the housing. Therefore, when vibration is applied to an external device, the vibration transmitted through the mounting portion is reduced, but since the vibration acts on the entire electronic device module, deformation occurs with the mounting piece portion of the electronic device module as a fixed point. End up. Here, it is known that the deformation of the entire electronic device module increases at a certain specific frequency (natural frequency). Thereby, the fluctuation | variation of a sensor output will arise. In order to avoid deformation of the entire electronic device module, it is necessary to increase the natural frequency and expand the frequency range in which the electronic device does not vibrate (deform) in response to externally applied vibration. In the technology described in Patent Document 1, no consideration is given to the suppression and reduction of the overall deformation of the module with the mounting piece as a fulcrum, and there is room for improvement with respect to making the eigenvalue of the entire electronic device module sufficiently high. .

  Accordingly, an object of the present invention is to provide a highly reliable sensor device in which sensor output fluctuation hardly occurs by suppressing or reducing deformation of the entire module.

  In order to solve the above problems, a physical quantity sensor device of the present invention includes, for example, a circuit board on which a sensor for detecting a physical quantity is mounted, a housing that houses the circuit board, and a housing that is fixed to an external device, and The width of the portion of the flange that contacts the case was set to 0.8 or more with respect to the width of the case.

  According to the present invention, it is possible to provide a highly reliable sensor device that is less likely to cause fluctuations in sensor output by suppressing or reducing deformation of the entire module.

The external view of the physical quantity sensor which makes this invention. Sectional drawing of the physical quantity sensor which makes this invention. The figure which shows the relationship between the housing natural frequency, the flange width, and the ratio of the housing case width. The figure which shows the relationship between the housing natural frequency, the thickness of a flange, and the ratio of the case bottom thickness of a housing.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, a physical quantity sensor mounting structure according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the physical quantity sensor device includes a circuit board 1 on which a sensor 2 for detecting various physical quantities is mounted, a connector 6 for inputting / outputting sensor output signals to / from an external device, and a case for housing the circuit board 1. 3a, a housing 3 in which a flange 5 for fixing to an external device is formed, and a cover 8. On the circuit board 1 on which the sensor 2 is mounted, a plurality of electronic components 4 having functions such as power supply and input / output communication control are mounted. The circuit board 1 is fixed to a predetermined part in the housing 3 with an adhesive 7 or the like, and an electrode (not shown) on the circuit board 1 and one end of the connector terminal are not shown in the figure. The other end of the terminal terminal is coupled to the connection terminal of the external device inside the connector 3.

  After the housing of the circuit board 1 in the case 3a and the connection of the fine metal wires are finished, the cover 8 is placed at a predetermined position of the housing 3, and the periphery of the cover is fixed with the adhesive 7 so that the opening of the housing 3 is opened. Covering. The physical quantity sensor device thus configured is used by being fixed to an external device by screwing attachment holes 9 formed in the two flanges 5 respectively.

  When vibration is applied from the outside while being fixed to an external device by screwing using two mounting holes 9 formed in the flange 5, the entire housing 3 has the base of the flange 5 (portion contacting the case 3 a). There is a case where deformation such as a fulcrum occurs. In order to suppress and reduce this deformation, it is effective to increase the rigidity of the flange 5.

  FIG. 3 shows the result of examining the dependence of the housing natural frequency on the flange width by finite element analysis when the flange thickness is constant. In FIG. 3, the horizontal axis represents the flange width t2 / case width t1, and the vertical axis represents the natural frequency of the housing normalized by a predetermined frequency. The eigenvalue is substantially constant when the ratio of the flange width t2 to the case width t1 is 0.8 or more. In the present invention, in order to increase the rigidity of the flange portion, the flange width t2 is set to 0.8 times or more of the case width t1. By increasing the rigidity of the flange 5 as described above, the natural frequency of the housing 3 can be increased, the frequency range in which deformation is caused by external vibration application can be widened, and the amount of deformation is also reduced. It becomes possible.

  The electronic component 4 includes components such as a microcomputer, a voltage regulator (regulator), a resistor, a capacitor, and a diode, and performs sensor control, power supply, external communication control, and the like. As the circuit board 1, a glass epoxy board or a ceramic board is used. The case portion of the housing 5, the connector 6, the flange 5, and the cover 8 are formed of PBT (polybutylene terephthalate) resin, PPS (polyphenylene sulfide) resin, or the like. An epoxy resin, a silicone resin, or the like is used for the adhesive 7 that fixes the circuit board 1 or the cover 8 to a predetermined portion of the housing 5.

  As a means for increasing the rigidity of the flange 5, there is an increase in flange width and a thickened flange portion as shown in FIG. FIG. 4 shows the result of the relationship between the ratio of the flange thickness t4 and the case bottom thickness t3 (flange thickness / case bottom thickness) shown in FIG. 2 and the natural frequency of the entire housing obtained by finite element analysis. The horizontal axis in FIG. 4 is the flange thickness t4 / case bottom thickness t3, and the vertical axis is the natural frequency of the housing normalized by a predetermined frequency. From the analysis result of FIG. 4, in the present invention, the flange thickness t4 is set so that the normalized natural frequency is 1 or more, and the flange thickness t4 is 3.6 times or more of the case bottom surface thickness t3. . As a result, the rigidity of the flange portion is increased, the amount of deformation of the entire housing with the flange root as a fulcrum is reduced, and the natural frequency is increased to increase the vibration resistance of the physical quantity sensor device.

  In order to increase the natural frequency of the entire housing, the case bottom thickness t3 also needs to have a predetermined thickness. In the housing structure and material system targeted by the present invention, it has been obtained that the case bottom thickness t3 is desirably 2.0 mm or more. In this case, the thickness of the flange t4 is 7.2 mm or more.

  As described above, by setting the ratio of flange width t2 / case width t1 to 0.8 or more and flange thickness t4 / case bottom thickness t3 to 3.6 or more, the rigidity of the flange portion for fixing the housing is increased. And the natural frequency of the entire housing can be increased. As a result, it is possible to suppress or reduce the deformation of the entire housing with the portion that contacts the case portion of the flange that is the housing fixing portion (the flange base portion) as a fulcrum, thereby suppressing or reducing the deformation of the entire physical quantity sensor. It is possible to provide a highly reliable sensor device that hardly causes fluctuations in sensor output.

DESCRIPTION OF SYMBOLS 1 ... Circuit board, 2 ... Sensor, 3 ... Housing, 3a ... Case, 4 ... Electronic component, 5 ... Flange, 6 ... Connector, 7 ... Adhesive, 8 ... Cover, 9 ... Hole, t1 ... Case width, t2 ... Flange width, t3 ... case bottom thickness, t4 ... flange thickness

Claims (2)

A circuit board on which sensors for detecting physical quantities are mounted;
A housing for housing the circuit board and a housing having a flange for fixing to an external device,
The physical quantity sensor device according to claim 1, wherein a width of a portion of the flange in contact with the case is 0.8 or more with respect to the width of the case. A circuit board on which a sensor for detecting a physical quantity is mounted; a housing for housing the circuit board; and a housing having a flange for fixing to an external device;
The physical quantity sensor device characterized in that the thickness of the flange is 3.6 times or more the thickness of the bottom surface of the case.