JP2011013010A - Method of manufacturing force detector and force detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a sensitive force detector with measurement accuracy enhanced in pressure detection by simplifying the structure of a force transfer member without using oil as a pressure receiving medium for its interior, and a force detector.SOLUTION: This method of manufacturing the force detector manufactures the force detector including: first and second fixed seats 70 and 80 comprising support faces that support bases 42 at both ends of a pressure-sensitive element 28; and a force transfer means extending in a direction in which the fixed seats 70 and 80 stand in line; with the transfer means erected on a pressure receiving means supported on a case and put through a through-hole in the fixed seat 70. This method has: a process for mounting a flat plat 90 on the support faces of the fixed seat and tentatively fixing the flat plate 90 so that respective normal lines with respect to the support faces of the fixed seats become parallel with each other; a process for bonding/fixing the fixed seat 70 to the transfer means; a process for fixing the fixed seat 80 to the case; and a process for removing the flat plate 90 tentatively fixed to the support faces and fixing the bases 42 at both ends of the sensitive element 28 to the support faces of the fixed seats, respectively.

Description

  The present invention relates to a force detector manufacturing method and a force detector improved so that fixing planes of support pedestals at both ends for fixing a pressure sensitive element are parallel to each other particularly in a housing structure such as a pressure sensor. .

  Conventionally, a pressure sensor using a piezoelectric vibrator as a pressure sensitive element is known as a water pressure gauge, a barometer, a differential pressure gauge, and the like. In the piezoelectric vibrator, for example, an electrode pattern is formed on a plate-like piezoelectric substrate, and the detection direction of force is set as a detection axis. When pressure acts in the direction of the detection axis, the piezoelectric vibrator The resonance frequency changes, and the pressure is detected from the change in the resonance frequency. Patent Documents 1 to 3 disclose a pressure sensor using a piezoelectric vibrator as a pressure sensitive element. When pressure is applied to the bellows from the pressure inlet, a force F corresponding to the effective area of the bellows is applied as a compressive force or a tensile force to the piezoelectric vibrating element via force transmitting means with a pivot (flexible hinge) as a fulcrum. Stress corresponding to the force F is generated in the piezoelectric vibrator, and the resonance frequency changes due to the stress. The pressure sensor measures pressure by detecting a change in resonance frequency generated in the piezoelectric vibrator.

Hereinafter, a conventional pressure sensor will be described using an example disclosed in Patent Document 1 and the like. FIG. 14 is a schematic diagram showing the structure of a conventional pressure sensor.
A conventional pressure sensor 101 shown in FIG. 14 includes a casing 104 having first and second pressure input ports 102 and 103 arranged to face each other, and a force transmission member 105 inside the casing 104. The other end of the first bellows 106 is connected to the first pressure input port 102 and the other end of the second bellows 107 is connected to the second pressure input port 103 so as to sandwich one end of the force transmission member 105. Yes. Further, a double tuning fork vibrator 109 is disposed as a pressure sensitive element between the other end of the force transmission member 105 and the end of the substrate 108 which is not a pivot (fulcrum).

  Here, in the pressure sensor, when the pressure is detected with high accuracy, the inside of the bellows is filled with liquid. As the liquid, oil such as silicon oil having high viscosity is generally used in order to prevent bubbles from entering or collecting in the bellows or the bellows portion.

  As described above, the first bellows 106 is filled with the viscous oil 110, and when the target of pressure measurement is a liquid, the opening 111 formed in the first pressure input port 102 is used. The liquid and the oil 110 are in contact and face each other. The opening 111 has an opening diameter that prevents the oil 110 from leaking to the outside.

  In the pressure sensor 101 having such a configuration, when the pressure F is applied to the oil 110 filled in the first bellows 106 from the liquid whose pressure is to be measured, the pressure F is passed through the first bellows 106. , Applied to one end of the force transmission member 105 (pivot-supported swing lever). On the other hand, atmospheric pressure is applied to the second bellows 107, and a force corresponding to atmospheric pressure is applied to one end of the force transmission member 105.

  As a result, the force corresponding to the differential pressure between the pressure F applied from the liquid whose pressure is to be measured via the other end of the force transmission member 105 and the pressure due to the atmospheric pressure is used as a fulcrum for the double tuning fork. When a compressive force or tensile force is applied to the mold vibrator 109, a stress is generated in the double tuning fork vibrator 109, and the resonance frequency changes according to the magnitude of the stress. By measuring the resonance frequency, The magnitude of the pressure F can be detected.

  On the other hand, in Patent Document 4, the first force as shown in FIG. 15A is used without using a force transmission means (cantilever) having an expensive pivot (flexible hinge) as a fulcrum as used in the above-described pressure sensor. A vibrator bonding base 215 is sandwiched between one end 210 a of the bellows 210 and one end 211 a of the second bellows 211, and the pressure sensitive element 220 is sandwiched between the base 215 and the housing wall on the other end side of the second bellows 211. A reinforcing plate 221 is disposed at a position facing the pressure-sensitive element 220 so as to fix each of both ends and sandwich the second bellows 211, and each of the both ends of the reinforcing plate 221 is connected to the pedestal 215. And a pressure sensor 201 fixed to the housing wall surface is disclosed.

  Further, in Patent Document 5 shown in FIG. 15 (B), regarding the pressure sensor disclosed in Patent Document 4, an elastic member 250a for reinforcing the base 215 and the housing in a direction orthogonal to the pressure detection axis direction of the bellows, A pressure sensor connected by using 250b has been proposed.

  Next, Patent Documents 6 and 7 shown in FIG. 16 disclose a pressure sensor 300 that is used by being fixed to an engine block in order to detect the hydraulic pressure inside the engine. The pressure sensor 300 includes a sensing unit 350 that outputs an electrical signal corresponding to an applied pressure, a pressure receiving diaphragm unit that receives pressure, and a pressure transmission member 360 that transmits pressure from the diaphragm to the sensing unit. Specifically, the first diaphragm 310 for pressure reception is provided on one end face of the hollow metal stem 330, the second diaphragm 322 for detection is provided on the other end face, and the first and second diaphragms 310 and 322 are provided in the stem. A force transmission member 360 is interposed between the two. The force transmission member 360 is a shaft made of metal or ceramic, and is interposed between the integral diaphragms with a prestress applied. Then, a chip 351 having a strain gauge function as a pressure detecting element is attached to the outer end surface of the second diaphragm 322, and the pressure received by the first diaphragm 310 is transmitted to the second diaphragm 322 by the force transmission member 360. The engine hydraulic pressure is detected by converting the electrical signal of the deformation of the diaphragm 322 by a strain gauge chip.

Japanese Patent Laid-Open No. 56-119519 Japanese Unexamined Patent Publication No. 64-9331 JP-A-2-228534 JP 2005-121628 A JP 2007-57395 A JP 2006-194736 A JP 2007-132597 A

  However, in the inventions of Patent Documents 1 to 3, the oil 110 filled in the first bellows 106, as in a pressure sensor as shown in FIG. Since the coefficient of thermal expansion is larger than that of the transmission member 105, the double tuning fork vibrator 109, etc., thermal deformation due to temperature change occurs in each member constituting the pressure sensor 101. Since such a thermal strain acts on the double tuning fork type vibrator 109 as an unnecessary stress, an error occurs in the measured pressure value, and the characteristic of the pressure sensor 101 is deteriorated.

  In addition, the oil 110 filled in the first bellows 106 is in contact with the liquid to be pressure-measured, and is opposed to the liquid. Or the liquid may flow into the first bellows 106 side, so that bubbles may be generated in the oil 110 filled in the first bellows 106. When bubbles are generated in the oil 110, the oil 110 functioning as a pressure transmission medium cannot stably transmit the force to the double tuning fork vibrator 109 via the force transmission member 105. An error may occur in the measurement.

  Further, as described above, since the oil 110 is in contact with and opposed to the liquid to be pressure-measured, the oil 110 can flow out to the liquid-side to be pressure-measured by the installation method of the pressure sensor 101. Therefore, there is a problem that the conventional pressure sensor 101 using the oil 110 cannot be used for measuring the pressure of a clean liquid that does not want to contain foreign substances.

  Furthermore, in the conventional pressure sensor 101, the force transmission member 105 has a complicated structure, which is an obstacle when the pressure sensor 101 is downsized. In addition, since the force transmission member 105 has a structure that requires a flexible hinge with a narrow constriction, the force transmission member 105 becomes a high-cost component, and thus there is a problem that the manufacturing cost of the pressure sensor 101 increases.

  The pressure sensors proposed in Patent Documents 4 and 5 cause the bellows to sag when the posture is tilted, which causes a change in the force applied to the pressure sensitive element (double tuning fork vibrator). There was a problem that the resonance frequency also fluctuated.

  Further, as shown in FIG. 17, a pipe 402 filled with oil is connected to the pressure inlet of the pressure sensor 400, and the other end of the pipe 402 is brought into contact with the liquid to be measured. Since the oil filled in the bellows or the pipe is in contact with the liquid to be pressure-measured as described in the above, the oil is measured by the pressure sensor 400 installation method. Or the liquid may flow into the bellows side, bubbles may be generated in the oil filled in the bellows. When bubbles are generated in the oil, it functions as a pressure transmission medium. Since the oil that is present cannot be stably transmitted to the double tuning fork vibrator via the pedestal 215, there is a problem that an error occurs in pressure measurement.

  Regarding Patent Document 5, if the hardness of the installed elastic member for reinforcement 250 is increased, the movement of the bellows is suppressed, and there is a problem that the pressure detection sensitivity is deteriorated.

  Further, in Patent Documents 4 and 5, since the reinforcing plate 221 is disposed opposite to the pressure-sensitive element 220, there is a problem that the movement of the bellows is suppressed and the pressure detection sensitivity is deteriorated.

  In Patent Documents 6 and 7, the diaphragms 310 and 322 and the pressure transmission member 360 are in contact with each other with a load applied. However, since the pressure sensor 300 is used at a high temperature and high pressure, it is fixed to the rigid. Since the mechanism may be destroyed due to the difference in thermal expansion of each member, the diaphragms 310 and 322 and the force transmission member 360 are merely in contact with each other in consideration of the thermal expansion, and are bonded. It is not bonded using bonding means such as an agent. Accordingly, when the diaphragms 310 and 322 and the force transmission member 360 are operated due to pressure fluctuation, there is a high possibility that the point contact portion will be displaced, and both the diaphragms 310 and 322 and the force transmission member 360 are in the process of shifting the contact point. Since the force acting on the air leaks, there is a problem that the pressure cannot be detected with high accuracy.

  Therefore, the present invention has been made in view of various problems as described above, i.e., without using oil as a pressure receiving medium inside, and by miniaturizing the structure of the force transmission member, It is an object of the present invention to provide a force detector manufacturing method and a force detector that are highly accurate and resistant to temperature shock.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1] A force extending in the direction in which the first and second fixed bases having support surfaces for supporting the bases at both ends of the pressure-sensitive element, and the first fixed base and the second fixed base are aligned. A force detector, wherein the force transmission means is inserted into the through hole of the first fixed base and is erected on the pressure receiving means supported by the case. Placing the flat plate on the support surface of the two fixed pedestals and temporarily fixing the flat plate so that the normals to the support surfaces of the first and second fixed pedestals are parallel to each other; A step of adhering and fixing one fixed base to the force transmitting means; a step of fixing the second fixed base to the case; and removing the flat plate temporarily fixed to the support surface to remove the both ends of the pressure-sensitive element. Fixing the base portions of the base plate to the support surfaces of the first and second fixing bases, respectively. Method for producing a force detector, characterized in that it comprises a.

  According to such a manufacturing method of the force detector, the support surface of the fixed base that supports both ends of the pressure sensitive element is easily aligned so that the axis of the force transmitting means and the detection axis of the pressure sensitive element are parallel. It is possible to avoid the strain stress acting on the pressure sensitive element due to the fixing failure. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

  Application Example 2 Temporarily fixing the second fixed base to the case so as to provide a predetermined distance between the surface of the second fixed base facing the force transmitting means and the force transmitting means. When the flat plate is temporarily fixed, the second fixed base is formed so that the support surface of the second fixed base and the support surface of the first fixed base form a continuous plane. The method for manufacturing a force detector according to application example 1, further comprising a step of temporarily fixing the case.

  Accordingly, when the second fixed base is aligned on the same plane as the support surface of the first fixed base, the displaced second fixed base can be easily moved to the same plane. it can. In addition, since the support surface can be aligned on the same plane with high accuracy, it is possible to more effectively avoid the strain stress acting on the pressure sensitive element due to the fixing failure.

  Application Example 3 Continuing on the support surface is a recess formed along the outer periphery of the pressure-sensitive element on the support surfaces of the first and second fixed bases that respectively support the bases at both ends of the pressure-sensitive element. Placing the flat plate having end portions of substantially the same shape as the outer shape of the bases at both ends of the pressure sensitive element, and temporarily fixing the flat plate so that the support surfaces are located on the same plane. A manufacturing method of a force detector according to application example 1 or 2, which is characterized.

  Thus, after positioning the support surfaces of the first and second fixed bases so that the axis of the force transmission means and the detection axis of the pressure sensitive element are parallel, the detection axis of the pressure sensitive element is aligned with the axis of the center shaft. It can be attached to be parallel. Therefore, it is possible to more effectively avoid the strain stress acting on the pressure-sensitive element due to the fixing failure.

Application Example 4 The method of manufacturing the force detector according to Application Example 3, wherein the side surface of the flat plate is in contact with the side surface of any one of the concavities facing the concave portion.
As a result, it is possible to easily align the fixed pedestal supporting both ends of the pressure sensitive element on the same plane without using the flat plate having substantially the same shape of the pressure sensitive element. It can be mounted so as to be parallel to the axis of the center shaft.

  Application Example 5 External force applied to the case, including a case for supporting the pressure receiving means, a force transmission means standing on the pressure receiving means, a pressure sensing portion, and a pair of bases connected to both ends of the pressure sensing portion. And a support surface for supporting the pair of base portions of the pressure-sensitive element so that the directions of the axis of the force transmitting means and the detection axis are parallel to each other. First and second fixed pedestals, and the first fixed pedestal has a through-hole through which the force transmitting means is inserted and faces the force transmitting means of the second fixed pedestal And the force transmission means, the second fixed base is assembled to the case so as to provide a predetermined interval.

  According to such a force detector, the fixed pedestal that supports both ends of the pressure sensitive element can be easily aligned so that the axis of the force transmitting means and the detection axis of the pressure sensitive element are parallel to each other. It is possible to avoid the strain stress acting on the pressure-sensitive element due to the above-mentioned problem. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

  [Application Example 6] The support surfaces of the first and second fixed bases include the support surface having a spreading direction parallel to the central axis of the force transmission means along the outer periphery of the pressure-sensitive element. The force detector according to Application Example 5, wherein the depressed portion is formed.

  As a result, the first and second fixed bases are positioned so that the axis of the force transmission means and the detection axis of the pressure sensitive element are parallel, and then the pressure sensitive elements are placed on the indicating surfaces of the first and second fixed bases. When mounting, the detection axis of the pressure-sensitive element can be mounted so as to be parallel to the axis of the center shaft. Therefore, it is possible to more effectively avoid the strain stress acting on the pressure-sensitive element due to the fixing failure. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

Application Example 7 The force detector according to Application Example 6, wherein a second recess is formed at a corner of the recess of the second fixed base.
Accordingly, when the flat plate or the pressure sensitive element is placed on the second fixed base, the holding means can enter the second recess and can be easily aligned.

It is a schematic cross section of the force detector which becomes a basic composition of the present invention. It is a perspective view of the principal part used as the basic composition of a force detector. It is a partially broken perspective view used as the basic composition of a force detector. It is a schematic cross section of the force detector of the present invention. It is a perspective view of the principal part of the force detector of this invention. It is a partially broken perspective view of the force detector of the present invention. It is explanatory drawing of the manufacturing method of a force detector. It is explanatory drawing of position alignment of the 1st and 2nd fixed base. It is a perspective view of the principal part of the force detector of the modification 1 of this invention. It is a perspective view of the principal part of the force detector which temporarily fixed the flat plate of the modification to the recessed part. It is a perspective view of the principal part of the force detector of the modification 2 of this invention. It is a perspective view of the principal part of the force detector of the modification 3 of this invention. It is explanatory drawing of the support surface of a 1st and 2nd fixed base. It is the schematic diagram which showed the structure of the conventional pressure sensor. It is explanatory drawing of the pressure sensor using the conventional base. It is explanatory drawing of the pressure sensor used for an engine block. It is explanatory drawing of the pressure sensor which connected the pipe.

A method for manufacturing a force detector and an embodiment of the force detector according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a force detector as a basic configuration of the present invention. 2 and 3 are a perspective view and a partially broken perspective view of a main part of a force detector as a basic configuration of the present invention. The force detector which is the basic configuration of the present invention will be described below using a pressure sensor as an example.

  The pressure sensor 10 has a housing 12 made of a hollow cylindrical body. The housing 12 has a flange end plate 14 as an end plate constituting a first case (lower end plate), a hermetic terminal block 16 as a second case (upper end plate), and a cylindrical side wall 18 as a third case. Is configured as a hollow hermetic container surrounding the periphery of the end plates arranged separately. A first pressure input port 17 and a second pressure input port 19 communicating with the internal space are passed through the flange end plate 14 and the hermetic terminal block 16 so as to be concentric with the shaft core of the housing 12 and open to the outside. . The opening is shielded from the inside and outside by a first diaphragm 20 and a second diaphragm 22 which are pressure receiving means, respectively, and these are integrally coupled to the flange end plate 14 and the hermetic terminal block 16. The first diaphragm 20 on the flange end plate 14 side is for pressure reception, and the second diaphragm 22 on the hermetic terminal block 16 side is for atmospheric pressure setting. The housing 12 is in a state where the inside and the outside are shut off, and the inside can be maintained in a vacuum state by an air vent means (not shown).

  Inside the housing 12, a center shaft (force transmission means) 24 that connects the central regions of the inner surfaces of the first and second diaphragms 20 and 22 to each other is disposed along the axis of the housing 12. Are bonded together. A movable portion 26 as a pressure-sensitive element cradle is provided in the middle of the center shaft 24. A detection axis, which will be described later, is parallel to an axis perpendicular to the pressure-receiving surfaces of the diaphragms 20 and 22. One end of a pressure sensitive element 28 composed of a double tuning fork vibrator set to be attached. The other end of the pressure-sensitive element 28 is connected to a boss 30 serving as a pressure-sensitive element receiving base projecting inwardly provided on the hermetic terminal block 16 of the housing 12. As a result, when the center shaft 24 moves in the axial direction due to the differential pressure between the first pressure receiving diaphragm 20 and the second atmospheric pressure diaphragm 22, the movable portion 26 changes its position following this, and this force is a pressure sensitive element. The acting force in the direction of the detection axis 28 is generated.

  The pressure-sensitive element 28 has a pressure-sensitive part 40 and a pair of base parts 42 connected to both ends of the pressure-sensitive part. The direction in which the pair of base parts 42 of the pressure-sensitive element 28 are arranged is a force detection direction. The force detection direction is set as the detection axis. When the pressure sensitive element 28 is a double tuning fork type piezoelectric vibrator, the pressure sensitive part 40 is constituted by two columnar beams (beams), and the direction in which the pair of base portions 42 are arranged, the direction in which the columnar beams extend, The detection axis is in parallel.

  The double tuning fork type vibration element has a pair of base portions 42 (first base portion 42 a and second base portion 42 b) that are fixed ends connected to both ends of the pressure-sensitive portion 40, and 2 between the two base portions 42. Two vibrating beams (vibrating parts) are formed. When a tensile stress (extension stress) or a compressive stress is applied to the two vibration beams that are the pressure-sensitive portion 40 (vibration portion) of the double tuning fork type vibration element, the resonance frequency is substantially equal to the applied stress. It has the characteristic of changing in proportion. The pressure sensitive element 28 is arranged so that the direction in which the pair of base portions 42 are arranged is parallel to the displacement direction in which the diaphragm is deflected and displaced, and the displacement direction is parallel to the detection axis. The first base portion 42 a of the pressure sensitive element 28 is fixed to the movable portion 26, and the second base portion 42 b is fixed to the boss portion 30.

  The pressure sensitive element 28 is electrically connected to an oscillation circuit (not shown), and vibrates at an inherent resonance frequency by an alternating current supplied from the oscillation circuit (not shown). The pressure frequency of the pressure-sensitive element 28 fluctuates by receiving an extension stress or a compressive stress from the direction of the detection axis. In particular, the double tuning fork type resonator element has an extremely large change in resonance frequency with respect to elongation / compression stress and a large variable range of resonance frequency compared to a thickness shear vibrator, etc. It is suitable for a pressure sensor that excels in resistance. When the double tuning fork type piezoelectric vibrator is subjected to elongation stress, the vibration width of the vibrating arm (vibrating part) is reduced, so that the resonance frequency is increased, and when receiving compressive stress, the vibration width of the vibrating arm (vibrating part) is increased. The resonance frequency is lowered.

  By the way, the double tuning fork type piezoelectric vibrator has two vibrating arms, while the single beam type piezoelectric vibrator has one vibrating arm. Therefore, when the single beam type piezoelectric vibrator is subjected to the same stress as that of the double tuning fork type piezoelectric vibrator from the direction of the detection axis, its displacement is doubled. It can be a sensitive pressure sensor. As the piezoelectric substrate of the double tuning fork type or single beam type piezoelectric vibrator, quartz having excellent temperature characteristics is desirable.

  Inside the housing 12, support rods 32a and 32b, which are parallel to the center shaft 24 and are a plurality of guide shafts, are disposed. These hold the gap between the flange end plate 14 as the first case and the hermetic terminal block 16 as the second case constant so that the detection accuracy does not deteriorate due to deformation of the housing 12 due to external force or an arbitrary posture. .

  In the present embodiment, in particular, the upper end plate is the Herme terminal block 16, and the Herme terminal 34 is penetrated through the terminal block 16 to take out the signal of the pressure sensitive element 28 to the outside.

  According to the pressure sensor 10 having such a configuration, the pair of diaphragms 20 and 22 are connected to the center shaft 24, and the movable portion 26 provided in the middle of the center shaft 24 is integrated according to the behavior of the diaphragms 20 and 22. (This is the movement caused by the pressure difference received by the pair of diaphragms 20 and 22), and the movement according to the force acting in the detection axis direction of the pressure sensitive element 28 which is a double tuning fork vibrator. It becomes. Therefore, a pressure sensor with high detection accuracy can be configured without using oil, and the structure is small and easy to assemble. Further, the flange end plate 14, the hermetic terminal block 16, and the cylindrical side wall 18 form a housing 12 as a vacuum container, the flange end plate 14 and the first diaphragm 20 are integrated, and the hermetic terminal block 16 and the second end plate 16 are integrated. The diaphragm 22 is integrated so that assembly can be performed easily. In order to attach the pressure sensor 10 to a container to be submerged (immersed) in the liquid to be measured, the flange end plate 14 is joined to the liquid container to be measured through an O-ring arranged so as to surround the first diaphragm 20. Install by bolting. Note that the center shaft 24 and the movable portion 26 as a pressure-sensitive element fixing pedestal may be an integral part cut from one member. By doing so, the movable portion 26 is prevented from being shaken or displaced at the fixed portion of the shaft.

  However, the fixing bases at both ends for fixing the both ends of the pressure sensitive element 28 are respectively fixed to the shaft 24 and the bosses serving as the other second fixing base. Since the portion 30 is provided on the hermetic terminal block 16 as a housing, the pressure-sensitive element fixing portion plane of the first fixed base and the pressure-sensitive element fixing portion plane of the second fixed base are not parallel to each other and are inclined. There is a problem that a means for fixing the fixing portion planes of the pedestal for fixing the both ends of the pressure sensitive element 28 so as not to be inclined or misaligned has not been established.

  In particular, the second fixed pedestal is formed at a predetermined interval so as not to come into contact with the center shaft 24, which serves as a force transmission means, because the detection accuracy decreases. For this reason, the center shaft 24 is arranged while being adjusted so as to be the center of the through-hole of the boss portion 30 while the second fixed pedestal is formed while being adjusted to be flush with the first fixed pedestal. Two adjustments were necessary, and it was difficult to adjust the alignment.

  FIG. 4 is a schematic cross-sectional view of the force detector of the present invention. FIG. 1A is a cross-sectional view of the force detector when the pressure-sensitive element is viewed from the side, and FIG. 2B is a cross-sectional view of the force detector when the pressure-sensitive element is viewed from the plane. FIG. 5 and FIG. 6 show a perspective view of main parts and a partially broken perspective view of a force detector as a basic configuration of the present invention. The force detector of the present invention will be described below using a pressure sensor as an example.

The difference from the pressure sensor 10 shown in FIG. 1 is the configuration of the movable portion 26 and the boss portion 30. Other configurations are the same as those in FIG. 1 and are denoted by the same reference numerals.
In the pressure sensor 100 serving as the force detector of the present embodiment, both ends of the pressure sensitive element 28 are fixed by the first and second fixing bases 70 and 80.

  The first fixed base 70 has a first through hole 72 through which the center shaft 24 is inserted at the center thereof. The first through hole 72 is set to have a diameter substantially the same as the shaft diameter of the center shaft 24, and the center shaft 24 and the first through hole center of the first fixed base 70 are on the same axis center by passing the center shaft 24. Can be positioned. Further, a screw hole 74 for temporary fixing is drilled in the fixing surface of the pressure sensitive element 28, and a second through hole 76 for introducing an adhesive is drilled in a pair of side surfaces 70a in a direction intersecting the screw hole 74. Yes.

  The second fixed pedestal 80 is a pedestal separated from the hermetic terminal block 16 and includes a fixing portion 82 for fixing the pressure sensitive element 28 and an attachment portion 84 for fixing to the hermetic terminal block 16. The fixing portion 82 is formed in substantially the same shape as the first fixing base 70, and a first through hole 83 through which the center shaft 24 is inserted is drilled in the center thereof. The hole diameter of the first through hole 83 is larger than the shaft diameter and is formed so as not to contact the shaft. The attachment portion 84 is formed on the hermetic terminal block 16 so that the attachment position can be adjusted. In this embodiment, a bolt 85 is used as an example of a fixing means for the hermetic terminal block 16 and the second fixing base 80, and is screwed into the second through hole 86 of the mounting portion 84 and the screw hole 16 a of the hermetic terminal block 16. ing. At this time, since the hole diameter of the second through hole 86 is larger than the shaft diameter of the bolt 85, the position where the second fixed base 80 is attached to the hermetic terminal block 16 is slightly smaller than the hole diameter of the second through hole. Can be adjusted. A screw hole 87 is drilled in the mounting surface of the pressure-sensitive element 28 of the second fixed base 80.

Next, the manufacturing method of the force detector of the present invention having the above configuration will be described below. FIG. 7 shows an explanatory view of the method of manufacturing the force detector of the present invention.
First, the second diaphragm 22 is joined to the pressure input port 19 of the hermetic terminal block 16 by welding. The second fixing base 80 is temporarily fixed with a bolt 85 on the surface of the hermetic terminal block 16 opposite to the pressure input port 19. At this time, the through holes of the hermetic terminal block 16 through which the center shaft penetrates and the second fixed base 80 are made to substantially coincide (FIG. 7 (1)).

On the other hand, the flange terminal plate 14 is held using the jig A, and the first diaphragm 20 is welded to the pressure input port 17 (FIG. 7B).
Further, the flange terminal plate 14 is sandwiched and held by the jig C having a center shaft 24 and a support rod 32 (32a, 32b) which is a guide shaft with the jig B together with the jig B. To do. The insertion through-holes are formed in advance at locations where the center shaft 24 attached to the first diaphragm 20 is attached and the support rods 32a and 32b attached to the flange terminal plate 14 are attached. In this state, the center shaft 24 and the support rods 32a and 32b are inserted. At this time, the center shaft 24 is applied such that an adhesive is applied to the tip, and the tip is erected vertically to the center of the first diaphragm 20. Further, the support rods 32a and 32b are attached in a state where the tips are embedded in the flange terminal plate 14 (FIG. 7 (3)).

  Next, the jig B and jig C are removed from the flange terminal plate 14, and the center shaft 24 is passed through the first through hole 72 of the first fixed base 70. An adhesive is applied to the ends of the center shaft 24 and the support rods 32a and 32b. Then, the cylindrical side wall 18 is fitted to the flange terminal block 14. The hermetic terminal block 16 is fitted through the opening of the cylindrical side wall 18 so as to face the flange terminal plate 14, and the tip of the guide shaft (support bar) 32 is embedded and bonded to the attachment position of the hermetic terminal block 16. The other end is bonded to the center of the second diaphragm 22 of the hermetic terminal block 16 (FIG. 7 (4)).

  The cylindrical side wall 18 is removed from the integrated flange terminal block 14 and hermetic terminal block 16, and the first and second fixed bases 70 and 80 are aligned. FIG. 8 is an explanatory diagram of the alignment of the first and second fixed bases. As shown in FIG. 8 (1), the first fixed base 70 can be aligned on the same axis by inserting the center shaft 24 through the first through hole 72. On the other hand, in the second fixed base 80, the first through hole 83 is larger than the shaft diameter of the center shaft 24, and the second through hole 86 of the attachment portion 84 is larger than the diameter of the bolt 85. There is a case where the position is displaced in a range corresponding to the clearance, that is, a radial range having a predetermined interval from the outer periphery of the center shaft 24.

  Therefore, in the present invention, the flat plate 90 is formed so as to be substantially the same along the outer shape of the pressure-sensitive element 28, in other words, using a flat plate 90 having end portions that are substantially the same as the outer shape of the base 42 at both ends of the pressure-sensitive element 28. Position adjustment is performed so that the support surfaces 70A and 80A of the first and second fixed bases 70 and 80 are on the same plane. The flat plate 90 is formed so as to be substantially the same along the outer shape of the pressure-sensitive element 28, and screw holes are formed at locations facing the screw holes of the first and second fixed bases 70 and 80.

  Such a flat plate 90 is temporarily fixed to the support surfaces of the first and second fixed bases 70 and 80 with screws 92 (FIG. 8B). By temporarily fixing the flat plate 90, the support surfaces of the first and second fixed bases 70 and 80 can be aligned on the same plane (forming a continuous plane).

  Thereafter, an adhesive is introduced into the second through hole 76 of the first fixed base 70, and the first fixed base 70 is bonded and fixed to the center shaft 24. Further, the bolt 85 temporarily fixing the second fixing base 80 to the hermetic terminal base 16 is finally tightened to fix the second fixing base 80 to the hermetic terminal base 16. (FIG. 8 (3)).

  After fixing, the flat plate 90 is removed, and the pair of base portions 42 of the pressure-sensitive element 28 are bonded to the second fixed base 80 of the hermetic terminal block 16 and the first fixed base 70 of the center shaft 24 by an adhesive or the like. And the pressure sensitive element 28 can be attached so that the detection axis is parallel to the axis of the center shaft 24. (FIG. 8 (4), FIG. 7 (5)).

  Finally, after performing the wiring process, the cylindrical side wall 18 is attached and the inside is sealed, and the inside is evacuated from the through hole provided in the hermetic terminal block 16, and the inside is shut off from the outside. Then, a circuit board on which an oscillation circuit for driving a pressure sensitive element composed of an IC or the like is mounted on the outer end surface portion of the hermetic terminal block 16 is mounted, and a lid 98 is attached to complete (FIG. 7 (6)). . Here, the lid 98 is formed with a pressure inlet for introducing pressure into the diaphragm 22 and a through hole through which a lead wire for leading an electric signal from the IC to the outside is formed. . The pressure inlet may be used in combination with the through hole.

  In this way, the fixed pedestals that support both ends of the pressure-sensitive element 28 can be easily aligned on the same plane, and the strain stress acting on the pressure-sensitive element 28 due to a fixing failure can be avoided. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

  The first and second fixed bases 70 and 80 are not necessarily formed on the same plane. FIG. 13 is an explanatory diagram of the support surfaces of the first and second fixed bases. Even if the first and second fixed bases 70 and 80 are not in a positional relationship where the support surfaces 70A and 80A are on the same plane, the first and second fixed bases 70 and 80, as shown in FIG. When the flat plate 90 is placed on the support surfaces 70A and 80A of 80, the normal lines A and B with respect to the support surfaces 70A and 80A of the first and second fixed bases 70 and 80 are parallel to each other. good. At this time, the flat plate 90 having the same base thickness at both ends (42a = 42b) is in contact with the support surface 80A of the second fixed base 80, but has a predetermined distance C from the support surface 70A of the first fixed base 70. Will be temporarily fixed. On the other hand, when the thicknesses of the pair of base parts connected to both ends of the pressure sensitive element 28 are different from each other (42a> 42b), the thickness of the base part 42a fixed to the first fixing base 70 is set to TA and the second fixing part. When the thickness of the base portion 42b fixed to the pedestal 80 is TB, if the relationship of TA = TB + C is satisfied, the pressure sensitive element 28 is fixed so that the axis of the center shaft and the detection axis are parallel. Can do. At this time, the thickness of the base portions at both ends of the flat plate 90 may be configured to correspond to the thickness of the base portions 42a and 42b of the pressure sensitive element 28.

  Further, the support surfaces 70A, 80A of the first and second fixed bases 70, 80 are not in the same plane, and the normal lines A, B are parallel to each other, and the thicknesses of both ends of the pressure sensitive element are the same. Either one of the supporting surfaces 70A and 80A is not in contact with either one. In this case, as shown in FIG. 13B, for example, the non-contact support surface 70A and the base portion 42a are temporarily fixed with a bolt 92 at a predetermined interval C, and the bolt 85 of the second fixed base 80 (not shown) is fully installed. After tightening, the pressure sensitive element may be fixed to the support surfaces 70A and 80A so that the center of the center shaft and the detection axis are parallel by filling the portion corresponding to the predetermined interval C with the adhesive means 93. Good.

  Next, a force detector according to the first modification will be described below. According to the manufacturing method of the force detector, the support surfaces of the first and second fixed bases 70 and 80 can be positioned on the same plane. Therefore, if the detection axis of the pressure-sensitive element 28 is arranged so as to be parallel to the axis of the center shaft 24, the strain stress acting on the pressure-sensitive element 28 due to a fixing defect can be avoided.

  However, if the detection axis of the pressure-sensitive element 28 is not attached so as to be parallel to the axis of the center shaft 24, strain stress acts on the pressure-sensitive element 28, resulting in a measurement error. Therefore, the strain stress resulting from the mounting failure of the pressure sensitive element 28 cannot be completely removed only by aligning the first and second fixed bases 70 and 80 on the same plane.

  FIG. 9 is a perspective view of the main part of the force detector of the first modification. As shown in FIG. 9A, the force detector according to the modified example is formed with a concave portion 94 into which the pressure sensitive element 28 is fitted in the first and second fixed bases 70 and 80. The concave portion 94 is formed along the outer periphery of the pressure sensitive element 28 on the support surfaces 70A and 80A of the first and second fixed bases 70 and 80 that respectively support the base portions 42 at both ends of the pressure sensitive element 28, and the pressure sensitive element 28. It is formed so as to be substantially the same according to the thickness. The recess 94 has a support surface having a spreading direction parallel to the center axis of the center shaft 24 as a bottom surface. Further, a screw hole 96 for temporarily fixing the flat plate is formed on the bottom surface of the recess 94.

  As shown in FIG. 9B, the manufacturing method of the force detector according to the first modification having the above-described configuration is configured such that the flat plate 90 is fitted into the recess 94 and temporarily fixed with the screw 92, and the first and second fixed bases 70, The 80 support surfaces can be positioned on the same plane. Thereafter, an adhesive is introduced into the second through hole 76 of the first fixed base 70, and the first fixed base 70 is bonded and fixed to the center shaft 24. Then, the bolt 85 temporarily fixing the second fixed base 80 to the hermetic terminal base 16 is finally tightened to fix the second fixed base 80 to the hermetic terminal base 16. Then, as shown in FIG. 9C, when the pressure-sensitive element 28 is fitted into the recess 94, the pair of base portions 42 of the pressure-sensitive element 28 are bonded to the first fixed base 70 and the second fixed base 80, respectively. By fixing using an adhesive means such as the above, the force detection direction of the pressure-sensitive element 28, that is, the detection axis direction and the axis of the center shaft 24 can be attached in parallel.

  According to such a force detector of the first modification, after the first and second fixed bases 70 and 80 are positioned on the same plane, the detection axis of the pressure sensitive element 28 is parallel to the axis of the center shaft 24. It can be attached to become. Accordingly, it is possible to avoid the strain stress acting on the pressure sensitive element 28 due to the fixing failure. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

  When the concave portion 94 is formed, the flat plate 90 continuing to the support surfaces of the first and second fixed bases 70 and 80 is necessarily formed so as to be substantially the same along the outer shape of the pressure sensitive element 28. There is no.

  FIG. 10 is a perspective view of the main part of the force detector in which the modified flat plate 91 is temporarily fixed to the recess 94. As shown in the drawing, the flat plate 91 of the modified example has a side surface 91a parallel to the center axis of the center shaft, and a side surface (95a and 95b, or 95c and 95d) of one of the concave portions facing the concave portion 94 ( In FIG. 10, it is only necessary to be in contact with 95b and 95d).

  Even when such a flat plate is used, the pedestal of the pressure-sensitive element 28 can be easily arranged on the same plane, or the normals to the support surfaces of the first and second fixed pedestals can be parallel to each other. Positioning can be performed, and distortion stress acting on the pressure-sensitive element 28 due to a fixing failure can be avoided. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

  Next, the force detector of Modification 2 will be described below. FIG. 11 is an explanatory diagram of a second fixed base 80 which is a main part of the force detector according to the second modification of the present invention. As shown in the drawing, the force detector according to the second modified example has a holding recess 96 serving as a second recess formed in the recess 94 of the second fixed base. The holding recess 96 is formed at a location in contact with the end of the pressure-sensitive element 28 placed in the recess 94. More specifically, as shown in FIG. 11 (A), the sandwiching recess 96 is shown at a corner 96a (B) in contact with the first side surface of the base parallel to the extending direction of the columnar beam of the pressure sensitive element 28. The first side surface and the second side surface of the pressure sensitive element 28 as shown in the corner 96b in contact with the second side surface of the base parallel to the direction perpendicular to the extending direction of the columnar beam of the pressure sensitive element 28, as shown in FIG. It is formed so as to be continuous with a corner portion 96c in contact with the side surface of the. Note that the thickness (depth) of the holding recess 96 is equal to or less than the thickness of the recess 94.

  Such a holding recess 96 is held by a holding means such as tweezers that holds the base of the pressure sensitive element 28 when the flat plate 90 or the pressure sensitive element 28 is placed on the second fixed base 80. It is possible to easily enter the concave portion 96 and align the position.

  FIG. 12 is a perspective view of the main part of the force detector according to the third modification of the present invention. As shown in the figure, the modified force detector is different in the shape of the second fixed base 180 from the second fixed base of the force detector shown in FIG. In the second fixed base 180 shown in FIG. 5A, a notch 183 is formed instead of the first through hole 83 of the second fixed base 80 shown in FIG. The notch 183 is formed in a groove shape along the axis of the shaft on the surface of the second fixed base 180 that faces the center shaft 24 so as to provide a predetermined space between the notch 183 and the center shaft 24.

Moreover, the 2nd fixed base 280 shown to (B) forms the fixing | fixed part 82 and the attaching part 84 used as the support surface 280A of a pressure-sensitive element in L shape. The second fixing base 280 is attached to the hermetic terminal block 16 so that the position of the fixing portion 82 facing the center shaft 24 can be adjusted so that a predetermined distance is provided between the second fixing base 280 and the center shaft 24.
Note that a recess 94 as shown in FIG. 9 may be formed on the support surfaces of the pressure sensitive elements of the first and second fixed bases 70, 180, and 280 shown in the third modification.

  Even in the force detector according to the third modification, the pedestal of the pressure-sensitive element 28 can be easily arranged on the same plane, or the normals to the support surfaces of the first and second fixed pedestals can be parallel to each other. Thus, the strain stress acting on the pressure-sensitive element 28 due to a fixing failure can be avoided. Further, a force detector having a simple structure with high detection accuracy can be manufactured without using oil.

10, 100 ... Pressure sensor, 12 ... Housing, 14 ... Flange end plate (first case), 16 ... Herme terminal block, 17 ... First pressure input port, 18 ... Cylindrical side wall, 19 ......... second pressure input port, 20 ......... first diaphragm, 22 ......... second diaphragm, 24 ......... center shaft, 26 ......... movable part, 28 ......... pressure sensitive element , 30 ......... Boss part, 32a, 32b ......... Support bar (guide shaft), 34 ......... Herme terminal, 40 ......... Pressure sensitive part, 42 ......... Base part, 70 ......... First fixing Pedestal 72 ......... First through hole 74 ......... Screw hole 76 ......... Second through hole 80 ......... Second fixed base 82 ......... Fixed portion 83 ......... First Through hole, 84 ......... Mounting part, 85 ......... Bolt, 86 ......... Second through hole, 87 ......... Screw hole, 90 ......... Plate, 92 ......... Screw, 93 ......... Adhesion means, 94 ......... Recess, 96 ......... Holding recess, 98 ......... Lid, 101 ......... Pressure sensor, 102 ......... First pressure inlet, 103 ......... Second pressure inlet, 104 ......... Housing, 105 ......... Force transmitting member, 106 ......... First bellows, 107 ......... Second bellows, 108 ……… Substrate, 109 ……… Two tuning fork vibrator, 110 ……… Oil, 111 ……… Opening portion, 201 …… Pressure sensor, 210 ……… First bellows, 211 ……… Second Bellows, 215... Vibrator adhering base, 220... Pressure sensitive element, 221... Reinforcing plate, 250 ... elastic member for reinforcement, 300 ... pressure sensor, 310 first Diaphragm, 330 ... hollow metal stem, 322 ... Second diaphragm, 50 ......... sensing unit, 351 ......... chip, 360 ......... force transmitting member, 400 ......... pressure sensor, 402 ......... pipe.

Claims (7)

First and second fixed bases having support surfaces for supporting bases at both ends of the pressure sensitive element;
Force transmitting means extending in a direction in which the first fixed base and the second fixed base are arranged;
A method of manufacturing a force detector, wherein the force transmitting means is erected on a pressure receiving means supported by a case in a through hole of the first fixed base,
A flat plate is placed on the support surfaces of the first and second fixed bases, and the flat plates are temporarily fixed so that the normals to the support surfaces of the first and second fixed bases are parallel to each other. Process,
Bonding and fixing the first fixing base to the force transmission means;
Fixing the second fixed base to the case;
Removing the flat plate temporarily fixed to the support surface and fixing the bases at both ends of the pressure sensitive element to the support surfaces of the first and second fixing bases, respectively;
A method for manufacturing a force detector. Temporarily fixing the second fixed base to the case so as to provide a predetermined interval between the force transmitting means and a surface of the second fixed base facing the force transmitting means;
When temporarily fixing the flat plate, the second fixed base is attached to the case so that a support surface of the second fixed base and a support surface of the first fixed base form a continuous plane. The method for manufacturing a force detector according to claim 1, further comprising a step of temporarily fixing.   The pressure-sensitive element that is continuous with the support surface in a recess formed along the outer periphery of the pressure-sensitive element on the support surfaces of the first and second fixed bases that respectively support the bases at both ends of the pressure-sensitive element. The flat plate having the ends substantially the same shape as the outer shapes of the base portions at both ends is placed, and the flat plate is temporarily fixed so that the support surfaces are located on the same plane. A method for manufacturing the force detector according to 1 or 2.   4. The method of manufacturing a force detector according to claim 3, wherein a side surface of the flat plate is in contact with a side surface of any one of the concave portions facing the concave portion. A case for supporting the pressure receiving means;
Force transmitting means standing on the pressure receiving means;
A pressure-sensitive element having a pressure-sensitive part and a pair of bases connected to both ends of the pressure-sensitive part, and having a detection axis as a direction for detecting an applied external force;
First and second fixed bases each having a support surface for supporting the pair of bases of the pressure-sensitive element so that directions of the axis of the force transmission means and the detection axis are parallel to each other;
With
The first fixed base has a through-hole through which the force transmitting means is inserted;
The second fixed base is assembled to the case so as to provide a predetermined interval between the surface of the second fixed base facing the force transmitting means and the force transmitting means. Force detector.   On the support surfaces of the first and second fixed bases, recesses are formed along the outer periphery of the pressure sensitive element, with the support surface having a spreading direction parallel to the central axis of the force transmission means as a bottom surface. The force detector according to claim 5, wherein:   The force detector according to claim 6, wherein a second recess is formed at a corner of the recess of the second fixed base.