JP2019060626A - Pressure detection device and assembling method thereof - Google Patents

Abstract

To provide a pressure detection device having a structure for suppressing superimposition of noise on a detection output of a pressure sensor due to distortion of a housing, and also to provide an assembling method of the pressure detection device.SOLUTION: A sensor unit 20 is stored in a storage space 15 of a housing 10. A pressure sensor 31 is fixed to an inner side of a housing 21 in the sensor unit 20. A holding side barrel part 14 is formed in the housing 10 and a held barrel part 23 is formed in the housing 21. The holding side barrel part 14 is pressurized to the held barrel part 23 by thermal stress, so as to hold the held barrel part 23 by the holding side barrel part 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure detection device in which a sensor unit having a pressure sensor is assembled to a housing and a method of assembling the same.

Patent Document 1 describes an invention related to a temperature sensor integrated pressure sensor device.
This temperature sensor integrated pressure sensor device has a resin head and a resin pipe. The pressure detection element is fixed to the resin head, and the pressure detection element is covered with a fluorine rubber protection member. A plurality of terminals are embedded in the resin head, and the pressure detection element and any of the terminals are connected by bonding wires and conducted.

  A communication pipe is formed inside the resin pipe, and the pressure is transmitted to the pressure receiving surface of the pressure detection element by the communication pipe. A temperature detection element is provided at an opening communicating with the communication pipe of the resin pipe, and a lead wire electrically connected to the temperature detection element is provided inside the resin pipe. The resin head and the resin pipe are fixed via an adhesive, and the lead wire is connected to any one of the terminals embedded in the resin head.

  In this temperature sensor integrated pressure sensor device, the pressure medium is led from the opening of the resin pipe to the communication pipe, the temperature detection element detects the temperature of the pressure medium, and the pressure sensor detects the pressure.

JP, 2008-261796, A

  In the temperature sensor integrated pressure sensor device described in Patent Document 1, since the resin head is fixed to the intake manifold or the like, distortion easily acts on the resin head by this fixing force. In addition, the resin head is formed with an opening through which the internal terminal is exposed, and the opening is fitted to and connected to an external device, but the resin head also has distortion due to the connection with the external device. Likely to happen.

  However, since the pressure detection element has a structure in which the pressure detection element is directly fixed to the resin head via the adhesive, the respective strains acting on the resin head are easily transmitted to the pressure detection element, and the pressure detection is performed. It is easy to generate a detection output that becomes noise in the element, and accurate pressure detection can not be performed.

  The present invention solves the above-described conventional problems, and aims to provide a pressure detection device capable of enhancing the accuracy of the detection output of the pressure sensor as a structure in which distortion of the casing is not easily transmitted to the pressure sensor. There is.

  Another object of the present invention is to provide a method of assembling a pressure detection device in which the sensor unit can be held in the casing by thermal stress in a simple process.

The present invention relates to a pressure detection device in which a sensor unit provided with a pressure sensor in a housing is assembled to a housing.
In the housing, a holding cylindrical portion, and a detection recess surrounded by the holding cylindrical portion and opened toward the housing are formed, and the pressure sensor is provided inside the detection concave,
In the housing, a holding side cylindrical portion and a communication hole communicating with the internal space of the holding side cylindrical portion are formed,
The holding side cylindrical portion is fitted to the outer surface or the inner surface of the held cylindrical portion, the housing is held by the housing, and a change in pressure can be transmitted to the pressure sensor through the vent. It is characterized by

  In the pressure detecting device according to the present invention, the holding side cylindrical portion is brought into close contact with the outer surface or the inner surface of the held cylindrical portion by thermal stress.

  In the pressure detection device according to the present invention, it is preferable that a portion of the holding side cylindrical portion fitted to the held cylindrical portion has a uniform thickness dimension over the entire circumference.

Further, according to the present invention, there is provided a method of assembling a pressure detection device in which a sensor unit provided with a pressure sensor in a housing is assembled to a housing.
(A) The pressure sensor is installed inside the detection recess of the housing having a holding cylindrical portion and a detection recess which is surrounded by the holding cylindrical portion and opens toward the housing,
(B) forming a holding side cylindrical portion and an air vent communicating with the internal space of the holding side cylindrical portion in the housing;
(C) The holding side cylindrical portion is heated to fit the holding side cylindrical portion to the outer surface or the inner surface of the held cylindrical portion, and the holding side cylindrical portion is held by the held cylindrical portion by thermal stress after cooling. In close contact with the outer surface or the inner surface of the part to hold the housing on the housing,
(D) A change in pressure can be transmitted to the pressure sensor through the vent.

  In the method of assembling a pressure detection device according to the present invention, in (c), the holding side tubular portion is heated to a temperature equal to or higher than the glass transition point.

  In the method of assembling a pressure detection device according to the present invention, in (c), the holding side cylindrical portion is deformed by heat, and the holding side cylindrical portion is deformed by thermal stress when the deformation is restored during cooling. It adheres to the outer surface or the inner surface of the held cylindrical portion.

  In the method of assembling a pressure detection device according to the present invention, for example, in (c), the holding side cylindrical portion is heated and deformed in a direction to reduce its outer diameter, and the holding cylindrical portion is made of the holding side cylindrical portion. Fit on the inner surface and cool.

  Alternatively, in the method of assembling a pressure detection device according to the present invention, in (c), the holding side cylindrical portion is heated and deformed in a direction to widen the inner diameter, and the held cylindrical portion is the inner surface of the holding side cylindrical portion. Fit in and cool.

  In the method of assembling a pressure detection device according to the present invention, the cooling of (c) is preferably natural cooling.

  In the pressure detection device of the present invention, the pressure sensor is provided inside the housing provided separately from the housing, and the held cylindrical portion provided at the tip of the housing is fitted to the holding side cylindrical portion of the housing doing. Preferably, the holding cylindrical portion is held by thermal stress when it is cooled and restored after the holding side cylindrical portion is heated and deformed. Since the housing and the housing are connected by fitting the holding cylindrical portion and the holding side cylindrical portion, distortion when acting on the housing when fixed to an internal combustion engine or the like, or connector connection with an external device The strain acting on the housing is less likely to act directly on the housing. As a result, noise caused by the distortion of the casing is less likely to be superimposed on the detection output of the pressure sensor.

  Further, as in the method of assembling a pressure detection device according to the present invention, the holding-side cylindrical portion provided in the casing is thermally deformed, and the holding-side cylindrical portion is held by the holding-side cylindrical portion Enables the sensor unit's housing to be firmly fixed to the housing without the need to apply an adhesive in a simple process, or using many adhesives even if an adhesive is used. become able to.

Sectional drawing of the pressure detection apparatus of embodiment of this invention, A front view (cross-sectional view along the line II-II in FIG. 1) of the sensor unit used in the pressure detection device shown in FIG. 1 as viewed from the housing side (pressure receiving side); (A), (B) and (C) are process drawings showing a first embodiment of a method of assembling a pressure detection device of the present invention; (A), (B), and (C) are process drawings showing a second embodiment of a method of assembling a pressure detection device of the present invention; A partial cross-sectional view showing a pressure detection device according to a second embodiment of the present invention;

The pressure detection device 1 illustrated in FIG. 1 includes a housing 10 and a sensor unit 20 attached to the housing 10.
The pressure detection device 1 is used as an intake pressure measurement device, and is attached to, for example, an internal combustion engine provided in a two-wheeled vehicle. The housing 10 is formed of a synthetic resin material such as PBT (polybutylene terephthalate). A sensor unit 20 for detecting pressure is attached to the housing 10. Further, although not shown, a throttle position sensor and a temperature sensor are mounted together on the housing 10.

  A space consisting of a part (pressure-sensitive space 13) of the case 10 and a part (detection recess 24) of the sensor unit 20 is formed inside the pressure-sensitive end portion 11 of the case 10, An air vent 12 communicating with the outside is formed in the wall on the pressure side end 11 side. The pressure detection device 1 is attached to the intake pipe of a two-wheeled vehicle, the pressure receiving end 11 is exposed to the inside of the intake pipe (not shown), and a part of the housing 10 (pressure sensitive space 13) and a part of the sensor unit 20 A space consisting of (detection recess 24) is connected to the inside of the intake pipe by the vent hole 12. As a result, the air pressure in the space and the air pressure in the intake pipe become the same.

  In the housing 10, a storage space 15 opened on the X2 side is formed. The concave pressure-sensitive space 13 communicating with the vent hole 12 is provided on the inner surface of the pressure-sensitive end 11 facing the storage space 15. Further, a holding side cylindrical portion 14 is integrally formed on the inner surface 11 a of the pressure receiving end 11 so as to surround the pressure sensitive space 13 from the inner surface 11 a of the pressure receiving end 11 in the X2 direction. The holding side cylindrical portion 14 has an inner wall surface 14a and an outer wall surface 14b. 2 corresponds to a cross-sectional view taken along the line II-II in FIG. 1, but as shown in FIG. 2, the cross-sectional shape of the holding side cylindrical portion 14 (the shapes of the inner wall surface 14a and the outer wall surface 14b) is true. It is a circular cylinder. The thickness dimension T of at least the portion of the holding side cylindrical portion 14 holding the sensor unit 20 is uniform over the entire circumference of the holding side cylindrical portion 14.

  As described later, the sensor unit 20 is attached to the holding side cylindrical portion 14, but the cross sectional shape of the holding side cylindrical portion 14 (the shape of the inner wall surface 14 a and the outer wall surface 14 b) conforms to the shape of the sensor unit 20. It may be oval or oval.

  As shown in FIGS. 1 and 2, the sensor unit 20 is provided with a housing 21. The housing 21 is formed of a synthetic resin material such as PPS (polyphenylene sulfide). The housing 21 has a main body 22 on the X2 side. As shown in FIG. 2, the main body 22 has a rectangular shape when viewed from the front. The housing 21 is integrally formed with a held cylindrical portion 23 projecting from the main body portion 22 in the X1 direction on the pressure receiving side. The held cylindrical portion 23 has an inner surface 23a and an outer surface 23b. The shape of the to-be-held cylinder portion 23 when viewed in the front view of FIG. 2 is similar to the cross-sectional shape of the holding side cylinder portion 14, and the inner surface 23 a and the outer surface 23 b are perfectly circular cylinders.

  In addition, the shape of the to-be-held cylinder part 23 may be elliptical shape or an oval shape. In this case, the cross-sectional shape of the holding side cylindrical portion 14 of the housing 10 is matched to the shape of the held cylindrical portion 23.

  As shown in FIGS. 1 and 2, the detection recess 24 is formed in the housing 21 so as to open in the X1 direction at the pressure receiving side end portion surrounded by the held cylindrical portion 23. As shown in FIG. 2, the opening shape of the detection recess 24 is circular, and the thickness dimension of the held cylindrical portion 23 is uniform in all circumferential directions. However, the opening center of the detection recess 24 may be at a position offset with respect to the opening center of the held cylindrical portion 23, and the plate thickness dimension of the held cylindrical portion 23 may be different depending on the location.

  At the bottom of the detection recess 24 of the housing 10, a sensor storage recess 25 is formed on the Z1 side, and a circuit storage recess 26 is formed on the Z2 side. The sensor storage recess 25 is continuous with the detection recess 24, and the sensor storage recess 25 is a part of the detection recess 24.

  A pressure sensor 31 is fixed to the bottom of the sensor housing recess 25. The pressure sensor 31 has a MEMS (Micro Electro Mechanical Systems) structure, and includes a diaphragm unit that receives pressure, and a strain sensing element such as a piezoresistive element or a piezoelectric element that detects deformation of the diaphragm section. The pressure sensor 31 is covered by an elastic body 27. The elastic body 27 is a gel-like viscoelastic body, and is, for example, a gel-like silicone resin or a fluorine resin.

  The elastic body 27 is hardened after the resin material in liquid form is supplied to the sensor housing recess 25 and then hardened, but in the process of supplying and hardening the resin material in liquid form, the surface 27a of the resin material facing the pressure receiving side has surface tension Is a concave curved surface.

  An IC package 32 is fixed to the bottom of the circuit housing recess 26. The integrated circuit in the IC package 32 incorporates an amplifier for amplifying the detection output from the pressure sensor 31, the temperature sensor, and a temperature compensation circuit based on the temperature measured by the temperature sensor. An elastic material 28 covering the IC package 32 is filled in the circuit housing recess 26. The elastic member 28 is formed by curing a liquid synthetic rubber or the like.

  In the sensor unit 20, a plurality of wiring boards 33 formed of a conductive metal are embedded in the housing 21. The electrode portions of the pressure sensor 31 and the IC package 32 and the wiring board 33 are connected by wire bonding.

  As shown in FIG. 1, the held cylindrical portion 23 of the housing 21 provided in the sensor unit 20 is inserted into, fitted in and fixed to the inside of the holding side cylindrical portion 14 of the housing 10. The holding cylindrical portion 23 is inserted into the holding side cylindrical portion 14 in a state where the holding side cylindrical portion 14 of the housing 10 is heated to a temperature above the glass transition point and softened. At this time, for example, if the diameter (outside diameter) of the outer surface 23 b of the held cylindrical portion 23 is slightly larger than the diameter (inner diameter) of the inner wall surface 14 a of the held side cylindrical portion 14, the held cylindrical portion 23 is When forcibly inserted into the holding side cylindrical portion 14, the softened holding cylindrical portion 14 is deformed so as to expand. After that, when natural cooling is performed, the holding side cylindrical portion 14 tries to restore to the original shape, and the holding cylindrical portion 23 is firmly held by the holding side cylindrical portion 14 by the thermal stress at that time. As a result, the internal space constituted by the pressure sensitive space 13 and the detection recess 24 is communicated with the outside through only the vent holes 12.

  Therefore, it is not necessary to apply an adhesive to the fitting portion between the holding cylindrical portion 23 and the holding side cylindrical portion 14, and even if the adhesive is applied, the amount of the adhesive may be small. In addition, since the relative position between the housing 10 and the sensor unit 20 can be finely adjusted when the holding side cylindrical portion 14 is softened, the adjustment can be made compared to the case where general strong fitting or press-fitting is performed. It is easy.

  After the housing 21 of the sensor unit 20 is held by the holding side cylindrical portion 14 inside the storage space 15 of the housing 10, the circuit board 34 is installed inside the storage space 15. A part of the wiring board 33 embedded in the housing 21 protrudes from the housing 21 to form a terminal portion 33a. When the circuit board 34 is installed, the terminal portion 33a is inserted into the through hole 34a, and the conductor pattern on the surface of the circuit board 34 and the terminal portion 33a are soldered and conducted.

  After the sensor unit 20 and the circuit board 34 are installed in the storage space 15, a sealing material 35 such as a urethane material is injected into the storage space 15, and the sensor unit 20 and the circuit board 34 are sealed. It is buried inside the material 35 and protected. As a result, even if a gap is formed between the held cylindrical portion 23 and the holding side cylindrical portion 14, the gap is sealed by the sealing material 35. The air pressure in the internal space configured with the detection recess 24 can be set to the same as the air pressure outside through the vent holes 12.

  In the pressure detection device 1, the pressure sensor 31 is fixed to the housing 21 of the sensor unit 20, and the housing 10 and the sensor unit 20 partially fit the holding cylindrical portion 23 and the holding side cylindrical portion 14. Are connected to each other. Moreover, since the holding side cylindrical portion 14 is formed with the same thickness T throughout the entire circumference, the held cylindrical portion 23 is held by the holding side cylindrical portion 14 with uniform thermal stress over the entire circumference.

  Therefore, a force when screwing and fixing the case 10 in the internal combustion engine, a force when connecting the case 10 to another external device, and a throttle position provided in the case 10 Even when distortion occurs in the housing 10 due to a force when the sensor is rotated, it is possible to prevent all the distortion from being transmitted to the housing 21. Further, since the housing 21 and the circuit board 34 are also connected by the elastically deformable terminal portion 33a, distortion is hardly transmitted from the circuit board 34 to the housing 21. Therefore, distortion of the housing 21 of the sensor unit 20 can be reduced, and it is easy to prevent noise due to distortion from being superimposed on the detection output of the pressure sensor 31.

Next, it is a part of the process of the assembling method of the pressure detection device 1. Two examples of the connection method of the housing | casing 10 and the sensor unit 20 are demonstrated.
FIG. 3 shows an assembling method of the first embodiment.
As shown in FIG. 3A, in the assembling method of the first embodiment, a pressure jig 41 is used. In the pressing jig 41, a pressing recess 42 opened in the X1 direction is formed. The inner peripheral surface of the pressing recess 42 is a pressing surface 42 a. The pressing surface 42a is a tapered surface whose inner diameter gradually increases in the X1 direction. The inner diameter D1 of the pressing surface 42a at the bottom of the pressing recess 42 on the X2 side is set smaller than the outer dimension D2 of the outer wall 14b which is a substantially cylindrical surface of the holding side cylindrical portion 14 formed in the housing 10. There is.

  The pressing jig 41 is made of metal and is heated to about 200 to 250 ° C. and used. In this case, the pressure surface 42 a is preferably at a temperature (for example, about 160 to 180 ° C.) higher than the glass transition point of the PBT resin forming the housing 10.

  As shown in FIG. 3B, when the pressing recess 42 of the heated pressing jig 41 is pressed against the outer wall surface 14 b of the holding side cylindrical portion 14 of the housing 10, the heat of the pressing jig 41 causes A direction in which the holding side cylindrical portion 14 heated by the holding side cylindrical portion 14 and pressed by the pressure jig 41 is shifted to the center by a pressure surface 42 a which is a tapered inner peripheral surface of the pressure recess 42. It is pressurized in the F1 direction, which is At this time, the holding side cylindrical portion 14 is heated to a temperature equal to or higher than the glass transition point to be softened, and is deformed in a direction close to the center.

  As shown in FIG. 3C, when the holding cylindrical portion 23 of the housing 21 of the sensor unit 20 is forcibly inserted into the holding side cylindrical portion 14 in a state where the holding side cylindrical portion 14 is softened, The inner wall surface 14a of the holding side cylindrical portion 14 is pushed outward by the outer surface 23b of the held cylindrical portion 23, and the holding side cylindrical portion 14 is deformed in the direction in which the inner diameter is expanded.

  Thereafter, when the holding side cylindrical portion 14 is naturally cooled, the holding side cylindrical portion 14 contracts and tries to restore the original shape. The thermal stress at this time generates a force that causes the inner wall surface 14a of the holding side cylindrical portion 14 to press the outer surface 23b of the holding cylindrical portion 23 toward the center in the F2 direction. The holding force for holding the holding cylinder portion 23 is obtained.

FIG. 4 shows an assembling method of the second embodiment.
As shown in FIG. 4A, a metal pressure jig 45 is used in this assembly method. The outer peripheral surface of the pressing jig 45 is a cylindrical pressing surface 46. The outer diameter dimension D3 of the pressing surface 46 is set larger than the inner diameter dimension D4 of the cylindrical inner wall surface 14a of the holding side cylindrical portion 14. Further, the inside diameter D4 of the inner wall surface 14a of the holding side cylindrical portion 14 is smaller than the outside dimension of the held cylindrical portion 23 of the housing 21 of the sensor unit 20.

  As shown in FIG. 4B, when the pressing jig 45 is heated and the pressing jig 45 is inserted into the holding side cylindrical portion 14 of the housing 10, the holding side cylindrical portion 14 has a glass transition point. It is heated and softened to the above temperature. By the pressing surface 46 of the pressing jig 45, the holding side cylindrical portion 14 is pressed in the F3 direction which is the direction away from the center. As a result, the softened holding side cylindrical portion 14 is deformed so as to expand the inner diameter dimension.

  As shown in FIG. 4C, in a state in which the holding side cylindrical portion 14 is softened, the held cylindrical portion 23 of the housing 21 of the sensor unit 20 is inserted into the inside of the holding side cylindrical portion 14 to hold the holding side cylinder. The section 14 is naturally cooled. At this time, the holding side cylindrical portion 14 tends to be restored to the original shape, and the inner wall surface 14a of the holding side cylindrical portion 14 is pressed against the outer surface 23b of the held cylindrical portion 23 by the thermal stress at this time. A force in the F4 direction is generated to press the portion 14 toward the center. This becomes the holding force for holding the held cylindrical portion 23 by the holding side cylindrical portion 14.

FIG. 5 is a cross-sectional view of a part of a pressure detection device 101 according to a third embodiment of the present invention.
In the pressure detection device 101, the holding side cylindrical portion 14 formed in the housing 10 is inserted into the detection recess 24 inside the held cylindrical portion 23 of the housing 21 provided in the sensor unit 20. For example, the outer dimensions of the holding side cylindrical portion 14 are formed slightly larger than the inner diameter size of the held cylindrical portion 23, and the holding side cylindrical portion 14 is heated and softened. Forcedly press-fit into the inside of the holding cylindrical portion 23. In the subsequent natural cooling, the holding side cylindrical portion 14 is pressed against the inner surface 23 a of the holding cylindrical portion 23, and the holding cylindrical portion 23 is held by the holding side cylindrical portion 14.

DESCRIPTION OF SYMBOLS 1 pressure detection apparatus 10 case 11 pressure receiving end 13 air vent 14 holding side cylinder part 14a inner wall surface 14b outer wall surface 15 storage space 20 sensor unit 21 housing 23 holding cylinder part 23a inner surface 23b outer surface 24 detection recess 25 sensor storage recess 26 circuit housing recess 27 elastic body 31 pressure sensor 32 IC package 41, 45 pressing jig 101 pressure detecting device

Claims (9)

In a pressure detection device in which a sensor unit provided with a pressure sensor in a housing is assembled to a housing,
In the housing, a holding cylindrical portion, and a detection recess surrounded by the holding cylindrical portion and opened toward the housing are formed, and the pressure sensor is provided inside the detection concave,
In the housing, a holding side cylindrical portion and a communication hole communicating with the internal space of the holding side cylindrical portion are formed,
The holding side cylindrical portion is fitted to the outer surface or the inner surface of the held cylindrical portion, the housing is held by the housing, and a change in pressure can be transmitted to the pressure sensor through the vent. Pressure detection device characterized by   The pressure detection device according to claim 1, wherein the holding side cylindrical portion is in close contact with an outer surface or an inner surface of the held cylindrical portion by a thermal stress.   The pressure detection device according to claim 1, wherein a portion of the holding side cylindrical portion fitted to the held cylindrical portion has a uniform thickness dimension over the entire circumference. In a method of assembling a pressure detection device, a sensor unit having a pressure sensor provided in a housing is assembled to a housing,
(A) The pressure sensor is installed inside the detection recess of the housing having a holding cylindrical portion and a detection recess which is surrounded by the holding cylindrical portion and opens toward the housing,
(B) forming a holding side cylindrical portion and an air vent communicating with the internal space of the holding side cylindrical portion in the housing;
(C) The holding side cylindrical portion is heated to fit the holding side cylindrical portion to the outer surface or the inner surface of the held cylindrical portion, and the holding side cylindrical portion is held by the held cylindrical portion by thermal stress after cooling. In close contact with the outer surface or the inner surface of the part to hold the housing on the housing,
(D) A method of assembling a pressure detection device, wherein a pressure change can be transmitted to the pressure sensor through the vent.   The method of assembling a pressure detection device according to claim 4, wherein in the step (c), the holding side tubular portion is heated to a temperature equal to or higher than a glass transition point.   In the above (c), the holding side cylindrical portion heated and softened is deformed, and the holding side cylindrical portion is brought into close contact with the outer surface or the inner surface of the held cylindrical portion by thermal stress when the deformation is restored during cooling. A method of assembling a pressure sensing device according to claim 4 or 5.   The method according to claim 6, wherein in (c), the holding side cylindrical portion is heated and deformed in a direction to reduce its outer diameter, and the held cylindrical portion is fitted to the inner surface of the holding side cylindrical portion and cooled. How to assemble a pressure sensing device.   The pressure according to claim 6, wherein in (c), the holding side cylindrical portion is heated and deformed in a direction to widen the inner diameter thereof, and the held cylindrical portion is fitted to the inner surface of the holding side cylindrical portion and cooled. How to assemble the detector.   The method of assembling a pressure sensing device according to any one of claims 4 to 8, wherein the cooling in (c) is natural cooling.

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