Pressure detection device

Abstract

To prevent separation of a coupling part joined to a pressure-receiving diaphragm in a flow path unit from the pressure-receiving diaphragm.SOLUTION: A pressure detection unit includes a pressure sensor and a first coupling part being a magnet. A flow path unit 20 includes a pressure-receiving diaphragm 22 made of resin and a second coupling part 23 being a magnetic material joined to the pressure-receiving diaphragm 22. In a state where the flow path unit 20 is attached to the pressure detection unit with a nut, the first coupling part and the second coupling part 23 are arranged in a state of being attracted to each other by magnetic force. The pressure-receiving diaphragm 22 is circular in planar view and has a circular recess 22A at its center in planar view. The second coupling part 23 is also circular in planar view and is joined to the recess 22A in a state of being in contact with the bottom surface 22Aa of the recess 22A, and filling an adhesive AD between the side surface 22Ab of the recess 22A and itself.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a pressure detection device.

Background Art

[0002] Conventionally, there is known a pressure detection device in which a flow path unit having a flow path for introducing a fluid is attached to a pressure detection unit, and the pressure of the fluid flowing through the flow path unit is detected by the pressure detection unit (see, for example, Patent Document 1). The pressure detection device disclosed in Patent Document 1 is provided with a first connecting portion formed by a magnet on a diaphragm of the pressure detection unit and a second connecting portion formed by a magnetic body on a diaphragm of the flow path unit.

[0003] In the pressure detection device disclosed in Patent Document 1, in a state where the flow path unit is attached to the pressure detection unit, the first connecting portion and the second connecting portion are arranged in a state of being attracted by magnetic force. Therefore, when the pressure of the fluid flowing through the flow path is a negative pressure, the second connecting portion is attracted toward the flow path side by the pressure of the fluid, and the first connecting portion connected to the second connecting portion by magnetic force is attracted toward the flow path side. Thereby, the pressure of the fluid can be detected as a negative pressure by the pressure detection unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the pressure detection device disclosed in Patent Document 1, the second connecting portion formed of a magnetic body is joined to the flat surface on the pressure detection unit side of the diaphragm of the flow path unit by an adhesive. However, since the second connecting portion is joined to the flat surface, a change in stress occurs at the joint portion between the flat surface and the second connecting portion due to the deformation of the diaphragm caused by a change in the fluid pressure. Then, as the operation of deforming the diaphragm is repeated, the joint portion deteriorates and the second connecting portion separates from the diaphragm, making it impossible to appropriately detect the fluid pressure.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to prevent a connecting portion joined to a pressure receiving diaphragm of a flow path unit from separating from the pressure receiving diaphragm in a pressure detection device including the flow path unit and the pressure detection unit.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention employs the following means. The pressure detection device according to the first aspect of the present invention includes a pressure detection unit that detects the pressure transmitted to the pressure detection part, a flow path unit in which a flow path for introducing a fluid is formed, and an attachment mechanism that detachably attaches the flow path unit to the pressure detection unit. The pressure detection unit has a pressure sensor having the pressure detection part and a first connection part joined to the pressure detection part. The flow path unit has a resin pressure receiving part that is displaced by receiving the pressure of the fluid flowing through the flow path and a second connection part joined to the pressure receiving part. Either one of the first connection part and the second connection part is formed by a magnet, and the other of the first connection part and the second connection part is formed by a magnet or a magnetic body. In a state where the flow path unit is attached to the pressure detection unit by the attachment mechanism, the first connection part and the second connection part are arranged in a state of being attracted by magnetic force. The pressure receiving part is formed in a circular shape in plan view, and a recess having a circular shape in plan view is formed at the center position. The second connection part is formed in a circular shape in plan view and is joined to the recess in a state of contacting the bottom surface of the recess and filling an adhesive between the second connection part and the side surface of the recess.

[0008] According to the pressure detection device according to the first aspect of the present invention, in a state where the flow path unit is attached to the pressure detection unit by the attachment mechanism, the first connection part joined to the pressure detection part and the second connection part joined to the pressure receiving part are arranged in a state of being attracted by magnetic force. Therefore, when the pressure of the fluid flowing through the flow path is a positive pressure, the second connection part joined to the pressure receiving part is pulled away from the flow path side by the pressure of the fluid, and the second connection part presses the first connection part toward the pressure detection part. As a result, the pressure of the fluid is detected as a positive pressure by the pressure detection part.

[0009] Further, when the pressure of the fluid flowing through the flow path is a negative pressure, the second connecting portion joined to the pressure receiving portion by the pressure of the fluid is attracted toward the flow path side, and the first connecting portion magnetically connected to the second connecting portion is attracted toward the flow path side. As a result, the pressure of the fluid is detected as a negative pressure by the pressure detection unit. Thus, according to the pressure detection device according to the first aspect of the present invention, while enhancing the speed and safety of the operation of changing the fluid introduced into the flow path, the pressure of the fluid can be accurately detected regardless of whether the pressure of the fluid is a positive pressure or a negative pressure.

[0010] Further, according to the pressure detection device according to the first aspect of the present invention, the second connecting portion is joined to both the bottom surface and the side surface of the recess by an adhesive. Therefore, even if a change in stress occurs at the joint portion between the second connecting portion and the pressure receiving portion due to deformation of the pressure receiving portion caused by a change in the pressure of the fluid, the state in which the second connecting portion is firmly joined to the pressure receiving portion is maintained. Thus, it is possible to prevent the connecting portion joined to the pressure receiving portion of the flow path unit from separating from the pressure receiving portion as compared with the case where the second connecting portion is joined only to a flat surface.

[0011] The pressure detection device according to the second aspect of the present invention further includes the following configuration in the first aspect. That is, the depth of the recess along the axis orthogonal to the pressure receiving portion is set to be not less than 1 / 3 times and not more than 1 / 2 times the length of the second connecting portion along the axis.

[0012] According to the pressure detection device according to the second aspect of the present invention, by setting the depth of the recess to be not less than 1 / 3 times the length of the second connecting portion, a sufficient area of the second connecting portion joined to the recess can be ensured, and the second connecting portion can be firmly joined to the pressure receiving portion. Further, by setting the depth of the recess to be not more than 1 / 2 times the length of the second connecting portion, it is possible to prevent the depth of the recess from becoming excessively long and impairing the followability of the pressure receiving portion to the pressure change.

[0013] The pressure detection device according to the third aspect of the present invention further includes the following configuration in the first aspect or the second aspect. That is, a first outer diameter when the bottom surface of the recess is viewed in plan is set to be 1 / 3 times or more and 1 / 2 times or less of a second outer diameter when a region where the fluid of the pressure receiving portion contacts is viewed in plan.

[0014] According to the pressure detection device according to the third aspect of the present invention, by setting the first outer diameter of the bottom surface of the recess to be 1 / 3 times or more of the second outer diameter of the region where the fluid of the pressure receiving portion contacts, it is possible to sufficiently secure the size of the outer diameter of the second connecting portion joined to the recess and sufficiently secure the suction force by which the second connecting portion and the first connecting portion are attracted by magnetic force. Further, by setting the first outer diameter of the bottom surface of the recess to be 1 / 2 times or less of the second outer diameter of the region where the fluid of the pressure receiving portion contacts, it is possible to prevent the first outer diameter of the bottom surface of the recess from becoming excessively large and impairing the followability with respect to the pressure change of the pressure receiving portion.

[0015] The pressure detection device according to the fourth aspect of the present invention further includes the following configuration in the first aspect or the second aspect. That is, an outer diameter of the first connecting portion centered on the axis is larger than an outer diameter of the second connecting portion centered on the axis.

[0016] According to the pressure detection device according to the fourth aspect of the present invention, it is possible to sufficiently secure the outer diameter of the first connecting portion and sufficiently secure the suction force by which the second connecting portion and the first connecting portion are attracted by magnetic force.

Advantages of the Invention

[0017] According to the present invention, in a pressure detection device including a flow path unit and a pressure detection unit, it is possible to prevent a connecting portion joined to a pressure receiving diaphragm of the flow path unit from separating from the pressure receiving diaphragm.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 14

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the pressure detection device 100 according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a front view showing the pressure detection device 100 according to an embodiment of the present invention. Fig. 2 is a view showing the state where the flow path unit 20 is removed from the pressure detection device 100 shown in Fig. 1. Fig. 3 is a sectional view taken along the line A-A showing the state where the flow path unit 20 is removed from the pressure detection device 100 shown in Fig. 1.

[0020] As shown in FIG. 1, the pressure detection device 100 of the present embodiment includes a pressure detection unit 10 attached to the installation surface S with fastening bolts (not shown), a flow path unit 20 in which a flow path 21 for fluid to flow is formed inside, and a nut 30 (attachment mechanism) for detachably attaching the flow path unit 20 to the pressure detection unit 10.

[0021] As shown in FIG. 1, the pressure detection unit 10 is attached to the installation surface S, and the flow path unit 20 is attached to the pressure detection unit 10 by the nut 30. The pressure detection device 100 is attached to the installation surface S in a state where the flow path unit 20 is attached to the pressure detection unit 10 by the nut 30 and integrated.

[0022] An inflow side pipe (not shown) for allowing fluid to flow into the inlet 21a of the flow path unit 20 shown in FIG. 3 is attached to the inlet 21a of the flow path unit 20, and an outflow side pipe (not shown) for allowing the fluid flowing out from the outlet 21b to flow is attached to the outlet 21b of the flow path unit 20. The pressure of the fluid flowing through the flow path 21 from the inlet 21a to the outlet 21b is detected by the pressure detection unit 10. Here, the fluid is, for example, a liquid such as blood or dialysate.

[0023] As shown in FIG. 3, the pressure detection unit 10 includes a main body 13 attached to the installation surface S. As shown in FIGS. 2 and 3, a cable 19 for electrically connecting a pressure sensor 12 disposed inside and an external control device (not shown) is attached to the main body 13 of the pressure detection unit 10 via a cable attachment nut 19a.

[0024] Next, the pressure detection unit 10 will be described in detail with reference to FIGS. 1 to 3. The pressure detection unit 10 shown in FIGS. 1 to 3 is a device that detects the pressure transmitted to the diaphragm (pressure detection part) 12a. The pressure detection unit 10 includes a connection part (first connection part) 11, a pressure sensor 12, a main body part 13 in which the pressure sensor 12 is arranged, a sensor holding part 14 that holds the pressure sensor 12 in the main body part 13, a sensor substrate 15 for transmitting power and electrical signals between the pressure sensor 12 and the cable 19, and a zero point adjustment switch 16 for performing zero point adjustment of the pressure sensor 12.

[0025] The connection part 11 is a permanent magnet formed in a cylindrical shape along the axis Y1, and is formed of, for example, neodymium or the like. The connection part 11 is joined to the second surface 12aB of the diaphragm 12a of the pressure sensor 12 by an adhesive (for example, an epoxy resin-based adhesive). As shown in FIG. 3, the end surface of the connection part 11 joined to the diaphragm 12a is formed to have a planar shape arranged on a plane orthogonal to the axis Y1. The connection part 11 maintains a state of attracting and contacting the connection part (second connection part) 23, which is a magnetic body, by the magnetic force of the permanent magnet. The connection part 23 of the flow path unit 20 will be described later.

[0026] In the above description, the connection part 11 is a permanent magnet and the connection part 23 is a magnetic body, but other embodiments may be used. For example, both the connection part 11 and the connection part 23 may be permanent magnets. Also, the connection part 11 may be a magnetic body and the connection part 23 may be a permanent magnet. As described above, in the pressure detection device 100 of the present embodiment, either one of the connection part 11 and the connection part 23 is formed of a magnet, and the other of the connection part 11 and the connection part 23 is formed of a magnet or a magnetic body. Hereinafter, an example in which the connection part 11 is a permanent magnet and the connection part 23 is a magnetic body will be described.

[0027] As shown in FIG. 3, the pressure sensor 12 includes a diaphragm 12a formed in a thin film shape from a corrosion-resistant material (e.g., sapphire), a strain gauge portion 12b joined to the second surface 12aB of the diaphragm 12a, and a base portion 12c that holds the diaphragm 12a.

[0028] The pressure sensor 12 is a strain-type sensor that outputs a pressure signal corresponding to a change in the resistance value of the strain gauge portion 12b that deforms in response to the pressure transmitted from the connecting portion 23 to the first surface 12aA of the diaphragm 12a. A through hole communicating with the diaphragm 12a is formed in the base portion 12c, and the second surface 12aB of the diaphragm 12a is maintained at atmospheric pressure. Therefore, the pressure sensor 12 is a sensor that detects gauge pressure based on atmospheric pressure. As shown in FIG. 2, when the flow path unit 20 is not attached to the pressure detection unit 10, the diaphragm 12a of the pressure sensor 12 is in a state of being exposed to the outside.

[0029] The sensor holding portion 14 is a member formed in a cylindrical shape around the axis Y1. Since the inner diameter of the upper end of the sensor holding portion 14 is smaller than the outer diameter of the pressure sensor 12, the pressure sensor 12 can be held so as not to come out upward. The sensor holding portion 14 holds the diaphragm 12a joined to the base portion 12c with an adhesive (adhesive glass).

[0030] The sensor substrate 15 includes an amplifier circuit (not shown) that amplifies the pressure signal output by the pressure sensor 12, an interface circuit that transmits the pressure signal amplified by the amplifier circuit to the pressure signal line (not shown) of the cable 19, a power supply circuit (not shown) that transmits the power supply voltage supplied from the outside via the cable 19 to the pressure sensor 12, a zero point adjustment circuit (not shown) that performs zero point adjustment when the zero point adjustment switch 16 is pressed, and the like. The zero point adjustment circuit is a circuit that adjusts to set the pressure signal output by the pressure sensor 12 at that time as a reference value (e.g., zero) when the zero point adjustment switch 16 is pressed.

[0031] Next, the flow path unit 20 will be described in detail with reference to FIGS. 3 to 6. FIG. 4 is a bottom view of the flow path unit 20 shown in FIG. 3. FIG. 5 is a cross-sectional view taken along the line A-A of the pressure detection device 100 shown in FIG. 1. FIG. 6 is a partially enlarged view of the flow path unit 20 shown in FIG. 5.

[0032] As shown in FIG. 3, the flow path unit 20 includes a flow path body 21A in which a flow path 21 for allowing a fluid to flow in a flow direction extending along an axis X from an inlet 21a to an outlet 21b is formed inside, a pressure receiving diaphragm 22 that receives the pressure of the fluid flowing through the flow path 21 and is displaced on a first surface 22a, and a connecting portion (second connecting portion) 23 joined to a second surface 22b of the pressure receiving diaphragm 22.

[0033] The pressure receiving diaphragm 22 is a member formed in a thin film shape from a corrosion-resistant material (for example, a silicone resin material). The pressure receiving diaphragm 22 is a member formed in a circular shape in a plan view with an axis Y2 as a central axis, and its outer peripheral edge portion is joined to the flow path 21 by adhesion or welding. Since the pressure receiving diaphragm 22 is formed in a thin film shape, it deforms in a direction along the axis Y2 due to the pressure of the fluid flowing through the flow path 21. As shown in FIG. 6, the pressure receiving diaphragm 22 has a circular shape in a plan view along the axis Y1, and a circular recess 22A is formed at the center position in a plan view.

[0034] The connecting portion 23 is a metal magnetic body formed in a cylindrical shape along an axis Y2 orthogonal to the pressure receiving diaphragm 22, and is formed of a steel material such as S45C defined by JIS standards. As shown in FIG. 4, the connecting portion 23 is formed in a circular shape in a plan view. As shown in FIG. 5, the connecting portion 23 is arranged in a state of being attracted by the magnetic force of the connecting portion 11, which is a permanent magnet, when the flow path unit 20 is attached to the pressure detection unit 10 by a nut 30.

[0035] As shown in FIG. 6, the connecting portion 23 is joined to the recess 22A in a state where it contacts the bottom surface 22Aa of the recess 22A and the adhesive AD is filled between the connecting portion 23 and the side surface 22Ab of the recess 22A. The connecting portion 23 is joined to the bottom surface 22Aa and the side surface 22Ab of the recess 22A by the adhesive AD. The adhesive AD is an epoxy resin-based adhesive.

[0036] On both the one end side and the other end side along the axis Y2 of the connecting portion 23, a C surface 23a is formed. The C surface 23a is a chamfered portion formed in an annular shape in the circumferential direction around the axis Y1 at the radial end portion orthogonal to the axis Y1. Since the C surface 23a is formed on both the one end side and the other end side along the axis Y2 of the connecting portion 23, it is the same regardless of which of the one end side and the other end side along the axis Y2 of the connecting portion 23 is joined to the bottom surface 22Aa of the recess 22A. Therefore, when the operator joins the connecting portion 23 to the bottom surface 22Aa of the recess 22A, the operation of checking the positions of the one end side and the other end side along the axis Y2 of the connecting portion 23 becomes unnecessary, and the workability is improved.

[0037] Also, compared with the case where the C surface 23a is not formed on the connecting portion 23, the volume of the gap between the connecting portion 23 joined to the bottom surface 22Aa of the recess 22A and the recess 22A increases. As a result, compared with the case where the C surface 23a is not formed on the connecting portion 23, the amount of the adhesive AD filled in the gap between the connecting portion 23 and the recess 22A increases, and the bonding force between the connecting portion 23 and the pressure-receiving diaphragm 22 increases.

[0038] The depth L1 of the recess 22A along the axis Y2 orthogonal to the pressure-receiving diaphragm 22 is set to be, for example, 1 / 3 times or more and 1 time or less the length L2 of the connecting portion 23 along the axis Y2. Also, the depth L1 may be set to be 1 / 3 times or more and 1 / 2 times or less the length L2. The first outer diameter D1 of the bottom surface 22Aa of the recess 22A in plan view is set to be 1 / 3 times or more and 1 / 2 times or less the second outer diameter D2 of the region where the fluid of the pressure-receiving diaphragm 22 contacts in plan view.

[0039] As shown in FIG. 5, when the flow path unit 20 is attached to the pressure detection unit 10, the connecting portion 23 of the flow path unit 20 is in contact with the first surface 12aA of the diaphragm 12a of the pressure detection unit 10. The connecting portion 23 transmits the pressure of the fluid flowing through the flow path 21 to the diaphragm 12a.

[0040] As shown in FIG. 5, when the flow path unit 20 is attached to the pressure detection unit 10, the axis Y1 and the axis Y2 are arranged at the same position. As shown in FIGS. 5 and 6, the outer diameter D3 of the connecting portion 11 centered on the axis Y1 is larger than the outer diameter D4 of the connecting portion 23 centered on the axis Y2.

[0041] Next, the structure for attaching the flow path unit 20 to the pressure detection unit 10 with the nut 30 will be described. As shown in FIG. 3, an annular groove portion 22d extending around the axis Y2 is formed on the outer peripheral surface of the lower end side of the flow path unit 20. On the other hand, an annular protrusion portion 30b extending around the axis Y2 is formed on the inner peripheral surface of the nut 30. The nut 30 formed of an elastically deformable material (for example, a resin material) is pushed toward the annular groove portion 22d, so that the annular protrusion portion 30b is engaged with the annular groove portion 22d.

[0042] In the state where the annular protrusion portion 30b is engaged with the annular groove portion 22d as shown in FIG. 3, a minute gap is provided between the outer peripheral surface of the annular protrusion portion 30b and the inner peripheral surface of the annular groove portion 22d. Therefore, the nut 30 can rotate relatively around the axis Y1 in the state of being attached to the pressure detection unit 10. Thereby, the operator can rotate the nut 30 around the axis Y1 in the state where the pressure detection unit 10 is fixed to the installation surface S.

[0043] As shown in FIG. 3, the nut 30 is an annular member having an internal thread 30a extending around the axis Y2 formed on the inner peripheral surface. The nut 30 is a mechanism for detachably attaching the flow path unit 20 to the pressure detection unit 10 by fastening or releasing the internal thread 30a to the external thread 17 formed on the pressure detection unit 10.

[0044] While holding the flow path unit 20, the operator rotates the nut 30 in the fastening direction (the direction indicated by "LOCK" in FIGS. 1 and 2) around the axis Y1, thereby fastening the female thread 30a of the nut 30 and the male thread 17 of the pressure detection unit 10. By fastening the female thread 30a of the nut 30 and the male thread 17 of the pressure detection unit 10, the connecting portion 23 gradually approaches the first surface 12aA of the diaphragm 12a and finally contacts the first surface 12aA of the diaphragm 12a, resulting in the state shown in FIG. 5.

[0045] Next, a method for manufacturing the pressure detection device 100 according to an embodiment of the present invention will be described. FIG. 7 is a flowchart showing the manufacturing method of the pressure detection device 100.

[0046] In step S101, the operator forms a recess 22A in the pressure-receiving diaphragm 22. As shown in FIG. 8, the operator places the flat pressure-receiving diaphragm 22 without the recess 22A on the lower mold 310. The lower mold 310 is formed with a depression 311 having a shape corresponding to the recess 22A.

[0047] The operator presses the upper mold 320 against the lower mold 310 on which the pressure-receiving diaphragm 22 is installed, inserts the protrusion 321 formed on the upper mold 320 into the depression 311 of the lower mold 310, and sets it to the state shown in FIG. 9. FIG. 9 is a cross-sectional view showing the state after forming the recess 22A in the pressure-receiving diaphragm 22. Since the depth L1 of the recess 22A is set to be equal to or less than 1 / 2 times the length L2 of the connecting portion 23 along the axis Y2, it is possible to prevent the problem that the pressure-receiving diaphragm 22 is excessively deformed and damaged.

[0048] In step S102, the operator removes the upper mold 320 from the lower mold 310 and joins the connecting portion 23 to the recess 22A formed in the pressure-receiving diaphragm 22. The operator applies an adhesive AD to the bottom surface 22Aa of the recess 22A, inserts the connecting portion 23 into the bottom surface 22Aa to which the adhesive AD is applied, and sets it to the state shown in FIG. 10. FIG. 10 is a cross-sectional view showing the state in which the connecting portion 23 is joined to the recess 22A of the pressure-receiving diaphragm 22.

[0049] In step S103, the operator joins the pressure-receiving diaphragm 22 to the flow path main body 21A. The operator joins the pressure-receiving diaphragm 22 to the flow path main body 21A by adhesion or welding so as to close an opening 21Aa formed in a cylindrical shape around the axis Y2 in the flow path main body 21A, and sets it to the state shown in FIG. 11. FIG. 11 is a cross-sectional view showing a state where the pressure-receiving diaphragm 22 is joined to the flow path main body 21A.

[0050] In step S104, the operator attaches the nut 30 to the flow path main body 21A. The operator pushes the nut 30 toward the annular groove portion 22d, elastically deforms the flow path main body 21A partially, and engages the annular protrusion portion 30b with the annular groove portion 22d, and sets it to the state shown in FIG. 12. FIG. 12 is a cross-sectional view showing a state where the nut 30 is attached to the flow path main body 21A.

[0051] Here, with reference to FIGS. 13 and 14, the joining state between the connecting portion 23 and the pressure-receiving diaphragm 22 when the pressure-receiving diaphragm 22 is deformed will be described. FIG. 13 is a cross-sectional view showing a state where the pressure-receiving diaphragm 22 of the flow path unit 20 of the present embodiment is deformed. FIG. 14 is a cross-sectional view showing a state where the pressure-receiving diaphragm 22C of the flow path unit of the comparative example is deformed.

[0052] As shown in FIG. 13, since the recess 22A is formed in the pressure-receiving diaphragm 22 of the present embodiment, even when the pressure-receiving diaphragm 22 is deformed, the state where the bottom surface 22Aa and the side surface 22Ab of the recess 22A hold the connecting portion 23 via the adhesive AD is maintained.

[0053] On the other hand, as shown in FIG. 14, since the pressure-receiving diaphragm 22C of the comparative example does not have the recess 22A, when the pressure-receiving diaphragm 22C is deformed, only the surface where the pressure-receiving diaphragm 22C and the connecting portion 23C come into contact is held by the adhesive AD. In the comparative example, a sufficient area filled with the adhesive AD that holds the joint between the pressure-receiving diaphragm 22C and the connecting portion 23C cannot be secured. Further, in the comparative example, the deformation of the pressure-receiving diaphragm 22C acts directly on the portion where the pressure-receiving diaphragm 22C and the connecting portion 23C come into contact. Therefore, when the deformation of the pressure-receiving diaphragm 22C is repeated, the bonding force at the portion where the pressure-receiving diaphragm 22C and the connecting portion 23C come into contact is likely to decrease.

[0054] The operations and effects of the pressure detection device 100 of the present embodiment described above will be described. According to the pressure detection device 100 of the present embodiment, in a state where the flow path unit 20 is attached to the pressure detection unit 10 by the nut 30, the connecting portion 11 joined to the diaphragm 12a and the connecting portion 23 joined to the pressure-receiving diaphragm 22 are arranged in a state of being attracted by magnetic force. Therefore, when the pressure of the fluid flowing through the flow path 21 is a positive pressure, the connecting portion 23 joined to the pressure-receiving diaphragm 22 is pulled away from the flow path 21 side by the pressure of the fluid, and the connecting portion 23 presses the connecting portion 11 toward the diaphragm 12a. As a result, the pressure of the fluid is detected as a positive pressure by the diaphragm 12a.

[0055] Further, when the pressure of the fluid flowing through the flow path 21 is a negative pressure, the connecting portion 23 joined to the pressure-receiving diaphragm 22 is attracted toward the flow path 21 side by the pressure of the fluid, and the connecting portion 11 magnetically connected to the connecting portion 23 is attracted toward the flow path 21 side. As a result, the pressure of the fluid is detected as a negative pressure by the diaphragm 12a. Thus, according to the pressure detection device 100 of the present embodiment, while enhancing the speed and safety of the operation of changing the fluid introduced into the flow path 21, the pressure of the fluid can be accurately detected regardless of whether the pressure of the fluid is a positive pressure or a negative pressure.

[0056] Further, according to the pressure detection device 100 of the present embodiment, the connecting portion 23 is joined to both the bottom surface 22Aa and the side surface 22Ab of the recess 22A by the adhesive AD. Therefore, even if a change in stress occurs at the joint portion between the connecting portion 23 and the pressure-receiving diaphragm 22 due to deformation of the pressure-receiving diaphragm 22 caused by a change in fluid pressure, the state in which the connecting portion 23 is firmly joined to the pressure-receiving diaphragm 22 is maintained. Thus, it is possible to prevent the connecting portion 23 joined to the pressure-receiving diaphragm 22 of the flow path unit 20 from separating from the pressure-receiving diaphragm 22, as compared with the case where the connecting portion 23 is joined only to a flat surface.

[0057] According to the pressure detection device 100 of the present embodiment, by setting the depth L1 of the recess 22A to be 1 / 3 times or more the length L2 of the connecting portion 23, a sufficient area of the connecting portion 23 joined to the recess 22A can be secured, and the connecting portion 23 can be firmly joined to the pressure-receiving diaphragm 22. Further, by setting the depth L1 of the recess 22A to be 1 / 2 times or less the length L2 of the connecting portion 23, it is possible to prevent the depth L1 of the recess 22A from becoming excessively long and impairing the followability of the pressure-receiving diaphragm 22 to pressure changes.

[0058] According to the pressure detection device 100 of the present embodiment, by setting the first outer diameter D1 of the bottom surface 22Aa of the recess 22A to be 1 / 3 times or more the second outer diameter D2 of the region where the fluid of the pressure-receiving diaphragm 22 contacts, a sufficient size of the outer diameter of the connecting portion 23 joined to the recess 22A can be secured, and a sufficient attractive force by which the connecting portion 23 and the connecting portion 11 are attracted by magnetic force can be secured. Further, by setting the first outer diameter D1 of the bottom surface 22Aa of the recess 22A to be 1 / 2 times or less the second outer diameter D2 of the region where the fluid of the pressure-receiving diaphragm 22 contacts, it is possible to prevent the first outer diameter D1 of the bottom surface 22Aa of the recess 22A from becoming excessively large and impairing the followability of the pressure-receiving diaphragm 22 to pressure changes.

[0059] According to the pressure detection device 100 of the present embodiment, a sufficient outer diameter of the connecting portion 11 can be secured, and a sufficient attractive force by which the connecting portion 23 and the connecting portion 11 are attracted by magnetic force can be secured.

Explanation of Reference Numerals

[0060] 10 Pressure detection unit 11 Connecting part (first connecting part) 12 Pressure sensor 12a Diaphragm (pressure detection part) 12aA First surface 12aB Second surface 12b Strain resistance part 12c Base part 13 Main body part 14 Sensor holding part 15 Sensor substrate 16 Zero point adjustment switch 17 Male screw 19 Cable 20 Flow path unit 21 Flow path 21A Flow path main body 21Aa Opening 21a Inlet 21b Outlet 22, 22C Pressure-receiving diaphragm (pressure-receiving part) 22A Recess 22Aa Bottom surface 22Ab Side surface 22a First surface 22b Second surface 22d Annular groove part 23, 23C Connecting part (second connecting part) 23a C surface 30 Nut (mounting mechanism) 30a Female screw 30b Annular protrusion part 100 Pressure detection device 310 Lower mold 311 Depression 320 Upper mold 321 Protrusion part AD Adhesive D1 First outer diameter D2 Second outer diameter D3 Outer diameter D4 Outer diameter L1 Depth S Installation surface X, Y1, Y2 Axes

Claims

1. A pressure detection unit that detects the pressure transmitted to the pressure detection part; A flow path unit in which a flow path for flowing a fluid is formed; An attachment mechanism for detachably attaching the flow path unit to the pressure detection unit, and the pressure detection unit includes a pressure sensor having the pressure detection part; a first connection part joined to the pressure detection part, and the flow path unit includes a resin pressure receiving part that is displaced by receiving the pressure of the fluid flowing through the flow path; a second connection part joined to the pressure receiving part, and either one of the first connection part and the second connection part is formed of a magnet, and the other of the first connection part and the second connection part is formed of a magnet or a magnetic body, in a state where the flow path unit is attached to the pressure detection unit by the attachment mechanism, the first connection part and the second connection part are arranged in a state of being attracted by magnetic force, the pressure receiving part is formed in a circular shape in plan view, and a recess having a circular shape in plan view is formed at the center position, the second connection part is formed in a circular shape in plan view, and is joined to the recess in a state of being in contact with the bottom surface of the recess and filling an adhesive between the second connection part and the side surface of the recess. A pressure detection device.

2. The pressure detection device according to claim 1, wherein a depth of the recess along an axis orthogonal to the pressure receiving part is set to be not less than 1 / 3 times and not more than 1 / 2 times a length of the second connection part along the axis.

3. The pressure detection device according to claim 1 or claim 2, wherein a first outer diameter of the bottom surface of the recess in plan view is set to be not less than 1 / 3 times and not more than 1 / 2 times a second outer diameter of a region where the fluid of the pressure receiving part contacts in plan view.

4. The pressure detection device according to claim 1, wherein an outer diameter of the first connecting portion centered on an axis orthogonal to the pressure receiving portion is larger than an outer diameter of the second connecting portion centered on the axis.

Images