Pressure Detector

Abstract

To suppress generation of a variation in pressure detection characteristics of a pressure detection unit.SOLUTION: A pressure detection device 100 includes: a pressure detection unit; a flow path unit 20; and a mounting part for detachably mounting the flow path unit 20 to the pressure detection unit. The pressure detection unit includes: a pressure detection diaphragm 12aA; and a sensor rod 12aC that is disposed in a center part CP of a first surface 12aA1 of the pressure detection diaphragm 12aA and projects toward the flow path unit 20 along a first axis Y1 orthogonal to the pressure detection diaphragm 12aA, and allows an end surface 12aC1 orthogonal to the first axis Y1 to be formed. The flow path unit 20 has a flow path diaphragm 22a, and displacement of the flow path diaphragm 22a in contact with the end surface 12aC1 is transmitted to the pressure detection diaphragm 12aA via the sensor rod 12aC while the flow path unit 20 is being mounted to the pressure detection unit by the mounting part.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] Conventionally, there is known a pressure detection device including a flow path unit in which a pressure transmission surface is formed in a part of a flow path through which a liquid flows, a pressure detection unit that detects the pressure transmitted to the pressure detection surface, and an attachment mechanism for detachably attaching these (see, for example, Patent Document 1). In the pressure detection device disclosed in Patent Document 1, the flow path unit is detachable from the pressure detection unit, so that a used flow path unit can be replaced with a new flow path unit.

[0003] The pressure detection device disclosed in Patent Document 1 uses an attachment mechanism to bring the pressure transmission surface of the flow path unit into contact with the pressure detection surface of the pressure detection unit, thereby transmitting the pressure of the liquid flowing through the flow path unit to the pressure detection surface via the pressure transmission surface. When replacing a used flow path unit with a new flow path unit, the attachment mechanism removes the used flow path unit from the pressure detection unit and attaches the new flow path unit to the pressure detection unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-15568 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the pressure detection device disclosed in Patent Document 1, the flow passage unit is attached to the pressure detection unit so that the entire area of ​​the pressure transmission surface of the flow passage unit is in direct contact with the pressure detection surface of the pressure detection unit. However, due to individual differences in the shape of the flow passage units or variations in the work involved in attaching the flow passage units to the pressure detection unit, some areas of the pressure transmission surface may not be in direct contact with the pressure detection surface. Even if the entire area of ​​the pressure transmission surface is in direct contact with the pressure detection surface, there may be a bias in the contact force between the two surfaces. In such cases, the pressure detection characteristics of the pressure detection unit change before and after replacing the flow passage unit.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a pressure detection device that can suppress fluctuations in the pressure detection characteristics of the pressure detection unit due to individual differences in the shape of the flow path unit and variability in the work involved in attaching the flow path unit to the pressure detection unit. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. A pressure detection device according to one embodiment of the present invention comprises a pressure detection unit that detects the pressure of a fluid, a flow path unit in which a flow path through which the fluid flows, and an attachment portion for detachably attaching the flow path unit to the pressure detection unit, wherein the pressure detection unit has a pressure detection diaphragm that displaces in response to the pressure transmitted from the flow path unit, and a pressure transmission member that is joined to the center of a first surface of the pressure detection diaphragm and protrudes toward the flow path unit along a first axis perpendicular to the pressure detection diaphragm, and has a tip surface perpendicular to the first axis, wherein the flow path unit has a flow path diaphragm that displaces in response to the pressure of the fluid flowing through the flow path, and when the flow path unit is attached to the pressure detection unit by the attachment portion, the displacement of the flow path diaphragm in contact with the tip surface is transmitted to the pressure detection diaphragm via the pressure transmission member.

[0008] According to the pressure detection device of the present invention, since the flow path unit is detachably attached to the pressure detection unit, when changing the fluid flowing through the flow path, the used flow path unit can be removed from the pressure detection unit and an unused flow path unit can be newly attached to the pressure detection unit. Therefore, when changing the fluid flowing through the flow path, the time-consuming cleaning work of the flow path is not required, and the speed of the work can be improved. In addition, since the unused flow path unit can be newly used, safety can be improved.

[0009] Furthermore, according to a pressure detection device of one embodiment of the present invention, when the flow path unit is attached to the pressure detection unit by the mounting portion, the displacement of the flow path diaphragm in contact with the tip surface of the pressure transmission member arranged at the center of the first surface of the pressure detection diaphragm is transmitted to the pressure detection diaphragm via the pressure transmission member.

[0010] Because the area of ​​the flow path diaphragm that contacts the tip surface of the pressure transmission member is only a portion of the entire area of ​​the flow path diaphragm, even if there are individual differences in the shape of the flow path unit or variations in the work involved in attaching the flow path unit to the pressure detection unit, the entire area of ​​the tip surface of the pressure transmission member reliably contacts the flow path diaphragm, making it possible to suppress variations in the pressure detection characteristics of the pressure detection unit due to individual differences in the shape of the flow path unit or variations in the work involved in attaching the flow path unit to the pressure detection unit.

[0011] Furthermore, according to the pressure detection device of one aspect of the present invention, the pressure detection unit has a pressure transmission member disposed at the center of the first surface of the pressure detection diaphragm, so that the shape of the pressure transmission member does not change even when the flow passage unit is replaced. Therefore, compared to the case where the pressure transmission member is provided in the flow passage unit, it is possible to prevent fluctuations in the pressure detection characteristics due to individual differences in the shape of the pressure transmission member.

[0012] Here, the fluctuation of the pressure detection characteristics means, for example, when an external force is applied to the pressure detection device, a change in the pressure detection value before the external force is applied and a change in the pressure detection value after the external force is applied even if the fluid pressure is constant. Also, the fluctuation of the pressure detection characteristics means, for example, a change in the pressure detection value when the fluid pressure is gradually increasing and a change in the pressure detection value when the fluid pressure is gradually decreasing even if the fluid pressure is the same.

[0013] In a pressure detection device according to one embodiment of the present invention, the pressure detection unit includes a sensor body having the pressure detection diaphragm, the pressure transmission member, and a base portion to which the pressure detection diaphragm is attached, and a accommodating member that accommodates the sensor body and contacts a second region on the outer periphery of a first region including the center of the pressure detection diaphragm while exposing the first region, and the accommodating member has a contact surface that contacts an end region of the flow path diaphragm when the flow path unit is attached to the pressure detection unit by the mounting portion, and it is preferable that a first length along the first axis from the first surface to the tip surface is 1.0 times or more and 1.3 times or less than a second length along the first axis from the first surface to the contact surface.

[0014] According to the pressure detection device having the above configuration, the first length along the first axis from the first surface of the pressure detection diaphragm to the tip surface of the pressure transmitting member is 1.0 times or more the second length from the first surface to the contact surface of the accommodating member. Therefore, the tip surface of the pressure transmitting member is disposed at the same position as the contact surface of the accommodating member or at a position protruding toward the flow path diaphragm side more than that, and the entire area of ​​the tip surface can be reliably brought into contact with the flow path diaphragm.

[0015] According to the pressure detection device having the above configuration, the first length along the first axis from the first surface of the pressure detection diaphragm to the tip surface of the pressure transmitting member is 1.3 times or less the second length from the first surface to the contact surface of the containing member. Therefore, the tip surface of the pressure transmitting member is prevented from excessively protruding toward the flow path diaphragm beyond the contact surface of the containing member, and fluctuations in the pressure detection characteristics due to excessive deformation of the flow path diaphragm can be prevented.

[0016] In the pressure detection device having the above-mentioned configuration, it is preferable that the pressure detection unit has four strain resistance parts joined to the second surface of the pressure detection diaphragm and connected to form a Wheatstone bridge circuit, and that the four strain resistance parts are joined to an area of ​​the second surface excluding the central portion.

[0017] According to the pressure detection device having the above configuration, the four strain resistance parts are bonded to the area of ​​the second surface of the pressure detection diaphragm excluding the central part, which makes it possible to suppress deterioration in pressure detection accuracy compared to a case where the strain resistance parts are disposed in the central part of the pressure detection diaphragm where displacement is suppressed by disposing a pressure transmitting member.

[0018] In a pressure detection device according to one embodiment of the present invention, the flow path unit extends cylindrically along a second axis perpendicular to the flow path and has a communication hole communicating with the flow path, the communication hole is blocked by the flow path diaphragm, and it is preferable that the outer diameter (D1) of the pressure transmission member is 0.2 to 0.6 times the inner diameter (D2) of the communication hole.

[0019] According to the pressure detection device having the above configuration, the outer diameter of the pressure transmission member is at least 0.2 times the inner diameter of the communicating hole of the flow path unit, so that the outer diameter of the pressure transmission member relative to the inner diameter of the communicating hole is sufficiently secured, and pressure changes of the fluid flowing through the flow path can be reliably transmitted to the pressure detection diaphragm.

[0020] Furthermore, according to the pressure detection device having the above configuration, the outer diameter of the pressure transmission member is 0.6 times or less the inner diameter of the communicating hole of the flow path unit, so that even if there are individual differences in the shape of the flow path unit or variations in the work involved in attaching the flow path unit to the pressure detection unit, the entire area of ​​the tip surface of the pressure transmission member can be reliably brought into contact with the flow path diaphragm.

[0021] In a pressure detection device according to one embodiment of the present invention, it is preferable that the base portion has an opening hole extending cylindrically along the first axis, the opening hole being blocked by the pressure detection diaphragm, and the outer diameter of the pressure transmission member is greater than or equal to 0.2 times and less than or equal to 0.5 times the inner diameter of the opening hole.

[0022] According to the pressure detection device having the above configuration, the outer diameter of the pressure transmission member is at least 0.2 times the inner diameter of the opening in the base portion, so that the outer diameter of the pressure transmission member relative to the inner diameter of the opening is sufficiently ensured, and the pressure detection diaphragm can be reliably displaced in response to the pressure transmitted from the pressure transmission member.

[0023] Furthermore, in the pressure detection device having the above configuration, the outer diameter of the pressure transmission member is 0.5 times or less the inner diameter of the opening hole of the base portion, which ensures a sufficient area of ​​the pressure detection diaphragm where the pressure transmission member is not disposed, and thus ensures a sufficient amount of displacement of the pressure detection diaphragm.

[0024] In a pressure detection device according to one embodiment of the present invention, it is preferable that the pressure detection unit has a biasing portion that generates a biasing force that biases the pressure detection diaphragm toward the flow path diaphragm along the first axis, and the mounting portion is configured to mount the flow path unit to the pressure detection unit in a state in which the tip surface of the pressure transmission member is brought into contact with the flow path diaphragm by the biasing force generated by the biasing portion.

[0025] According to the pressure detection device having the above-mentioned configuration, the mounting portion attaches the flow path unit to the pressure detection unit in a state in which the tip face of the pressure transmission member is brought into contact with the flow path diaphragm by the biasing force generated by the biasing portion. Since the tip face of the pressure transmission member is brought into contact with the flow path diaphragm by the biasing force generated by the biasing portion, the strength of the force with which the tip face contacts the flow path diaphragm becomes constant, and it is possible to prevent fluctuations in the pressure detection characteristics of the pressure detection unit. Effect of the Invention

[0026] According to the present invention, a pressure detection device can be provided that can suppress fluctuations in the pressure detection characteristics of the pressure detection unit due to individual differences in the shape of the flow path unit or variations in the work involved in attaching the flow path unit to the pressure detection unit. [Brief description of the drawings]

[0027] [Figure 1] 1 is a plan view showing a pressure detection device according to an embodiment of the present invention; [Diagram 2] 2 is a plan view showing a state in which a flow path unit is removed from the pressure detection device shown in FIG. 1. [Diagram 3] 2 is a front view showing a state in which a flow path unit is removed from the pressure detection unit shown in FIG. 1. [Figure 4] 4 is a partial cross-sectional view of a flow path unit and a mounting portion shown in FIG. 3. [Diagram 5] 4 is a vertical sectional view of the pressure detection unit shown in FIG. 3. [Figure 6] FIG. 2 is a front view of the pressure detection device shown in FIG. [Figure 7] 11 is a front view showing the pressure detection device in a state where the mounting portion is being rotated from the release position to the lock position. FIG. [Figure 8] 11 is a front view showing the pressure detection device in a state where the mounting portion is rotated to a lock position. FIG. [Figure 9] FIG. 9 is a plan view of the pressure detection device shown in FIG. [Figure 10] 9 is a vertical sectional view of the pressure detection unit shown in FIG. 8. [Figure 11] FIG. 11 is a partial enlarged view of a portion A of the pressure detection device shown in FIG. 10, showing a state in which the pressure detection diaphragm is not pressurized. [Figure 12] 12 is a cross-sectional view of the pressure detection device shown in FIG. 11 taken along the line BB. [Figure 13] FIG. 1 is a diagram showing a Wheatstone bridge circuit formed by connecting four strain resistor parts by metal wiring. [Figure 14] 11 is a partially enlarged view of a portion A of the pressure detection device shown in FIG. 10, showing a state in which the pressure detection diaphragm is pressurized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A pressure detection device 100 according to an embodiment of the present invention will now be described with reference to the drawings. As shown in Figures 1 and 2, the pressure detection device 100 of this embodiment includes a pressure detection unit 10 attached to an installation surface S (see Figure 3) with fastening bolts (not shown), a flow path unit 20 having a flow path 21 formed therein that allows a fluid to flow along a linear flow direction from an inlet 21a to an outlet 21b, and an attachment portion 30 that detachably attaches the flow path unit 20 to the pressure detection unit 10.

[0029] In the pressure detection device 100 of this embodiment, the flow path unit 20 is attached to the pressure detection unit 10 by the attachment portion 30. The pressure detection device 100 is attached to an installation surface S in a state in which the flow path unit 20 is attached to the pressure detection unit 10 by the attachment portion 30 and integrated with the pressure detection unit 10.

[0030] 3, an inlet piping (not shown) for allowing a fluid to flow into the inlet 21a is attached to the inlet 21a of the flow path unit 20, and an outlet piping (not shown) for allowing the fluid to flow out of the outlet 21b 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 dialysis fluid.

[0031] As shown in Fig. 3, the pressure detection unit 10 includes a main body 11 that is attached to an installation surface S. As shown in Figs. 1 and 2, a cable 50 that electrically connects a sensor unit 12 disposed inside the main body 11 of the pressure detection unit 10 to an external control device (not shown) is attached via a cable mounting nut 50a.

[0032] Next, the pressure detection unit 10 will be described in detail with reference to Figs. 1 to 5. The pressure detection unit 10 shown in Figs. 1 to 5 is a device for detecting the pressure of a fluid transmitted to a pressure detection diaphragm 12aA. Fig. 3 is a front view showing a state in which the flow path unit 20 is removed from the pressure detection unit 10 shown in Fig. 1. Fig. 4 is a partial cross-sectional view of the flow path unit 20 and the mounting portion 30 shown in Fig. 3. Fig. 5 is a vertical cross-sectional view of the pressure detection unit 10 shown in Fig. 3.

[0033] As shown in FIG. 5, the pressure detection unit 10 has a main body portion 11, a sensor portion 12, a holding portion 13, a biasing portion 14, a sensor substrate 15, a zero point adjustment switch 16 (see FIG. 1), and a guide member (guiding portion) 18.

[0034] 5, the sensor unit 12 has a sensor body 12a, a housing member 12b, and a support member 12c. The sensor body 12a has a pressure-detecting diaphragm 12aA to which a strain resistor is attached, a base portion 12aB to which the pressure-detecting diaphragm 12aA is attached, and a sensor rod (pressure transmitting member) 12aC. The sensor body 12a is a strain-type sensor that outputs a pressure signal according to a change in the resistance value of a strain resistor that deforms together with the pressure-detecting diaphragm 12aA in response to the transmitted pressure.

[0035] The base portion 12aB has an opening 12aB1 (see FIG. 11) that communicates with the pressure-detecting diaphragm 12aA, and the opening 12aB1 is blocked by the pressure-detecting diaphragm 12aA. The second surface 12aA2 of the pressure-detecting diaphragm 12aA is maintained at atmospheric pressure. Therefore, the sensor body 12a is a sensor that detects a gauge pressure based on atmospheric pressure. The pressure-detecting diaphragm 12aA is formed in a thin film shape from a corrosion-resistant material (e.g., sapphire). The pressure-detecting diaphragm 12aA is displaced according to the pressure transmitted from the flow path unit 20 via the sensor rod 12aC.

[0036] 5, the housing member 12b extends along the first axis Y1 and is formed in a cylindrical shape, and is a member that houses the sensor main body 12a therein. An internal thread 12bA is formed on the inner peripheral surface of the housing member 12b. The internal thread 12bA engages with an external thread 12cA formed on the outer peripheral surface of the support member 12c.

[0037] The lower end of the housing member 12b is provided with slits 12bB formed at two locations in the circumferential direction and opening toward the lower end. When an operator rotates the mounting part 30 around the axis Y, the slits 12bB are inserted into the anti-rotation pins 14c that prevent the sensor part 12 from rotating together with the mounting part 30 around the axis Y.

[0038] As shown in Fig. 5, the support member 12c extends along the first axis Y1 and is formed in a cylindrical shape, and is a member that supports the sensor main body 12a inside the housing member 12b. A male thread 12cA is formed on the outer circumferential surface of the support member 12c. The sensor main body 12a is inserted into the housing member 12b, and the male thread 12cA of the support member 12c is fastened to the female thread 12bA of the housing member 12b to fix the sensor main body 12a inside the housing member 12b.

[0039] The holding portion 13 is a member that extends along the first axis Y1 and is formed into a cylindrical shape, and holds the sensor portion 12 movably along the first axis Y1 perpendicular to the pressure detecting diaphragm 12aA. The holding portion 13 has a main body portion 13a, a fixing member 13b, and an O-ring 13c. The O-ring 13c that comes into contact with the outer circumferential surface of the housing member 12b of the sensor portion 12 is attached to the inner circumferential surface of the main body portion 13a.

[0040] A male thread 13aA is formed on the outer peripheral surface of the lower end of the main body 13a, and a female thread 13bA is formed on the inner peripheral surface of the fixing member 13b. The main body 13a is fixed to the guide member 18 attached to the main body 11 by fastening and tightening the female thread 13bA of the fixing member 13b to the male thread 13aA of the main body 13a.

[0041] The biasing portion 14 generates a biasing force that biases the sensor portion 12 toward the flow path diaphragm 22a of the flow path unit 20. The biasing portion 14 has a spring 14a, a base member 14b, and a rotation prevention pin 14c. The spring 14a is disposed with one end in contact with the base member 14b fixed to the main body portion 11 and the other end in contact with the support member 12c of the sensor portion 12. The spring 14a generates a biasing force according to the distance along the first axis Y1 from the one end in contact with the base member 14b to the other end.

[0042] The anti-rotation pin 14c is a member formed in a shaft shape extending in a direction perpendicular to the first axis Y1, and is fixed to the base member 14b. The anti-rotation pin 14c is inserted into a pair of slits 12bB formed in the lower end of the housing member 12b. The anti-rotation pin 14c prevents the sensor unit 12 from rotating together with the mounting unit 30 around the first axis Y1 when the operator rotates the mounting unit 30 around the first axis Y1.

[0043] The sensor board 15 includes an amplifier circuit (not shown) that amplifies the pressure signal output by the sensor main body 12a, an interface circuit that transmits the pressure signal amplified by the amplifier circuit to a pressure signal line (not shown) of the cable 50, a power supply circuit (not shown) that transmits a power supply voltage supplied from the outside via the cable 50 to the sensor main body 12a, and a zero point adjustment circuit (not shown) that performs zero point adjustment when the zero point adjustment switch 16 is pressed. The zero point adjustment circuit is a circuit that adjusts the pressure signal output by the sensor main body 12a at the time when the zero point adjustment switch 16 is pressed so as to set it as a reference value (for example, zero).

[0044] 3 and 5, the sensor portion 12 and the holder 13 of the pressure detection unit 10 protrude upward from the main body portion 11 along the first axis Y1, with the pressure detection diaphragm 12aA located at the top. As shown in Fig. 2 and Fig. 3, the holder 13 has a pair of protrusions 13aB protruding from the outer circumferential surface of the main body portion 13a in a direction perpendicular to the first axis Y1.

[0045] 2, the protrusions 13aB formed on the outer peripheral surface of the holding portion 13 are formed at two locations spaced apart by 180° around the axis Y. As shown in FIG 2, when the flow path unit 20 is not attached to the pressure detection unit 10, the pressure detection diaphragm 12aA of the sensor portion 12 is exposed to the outside.

[0046] The guide member 18 has a groove portion 18a that guides the flow passage 21 to a predetermined mounting position when the flow passage unit 20 is attached to the pressure detection unit 10. The guide members 18 are provided in a pair at positions symmetrical with respect to the first axis Y1. The pair of guide members 18 guide a part of the flow passage 21 on the inlet 21a side and a part of the flow passage 21 on the outlet 21b side to the predetermined mounting positions, respectively.

[0047] Next, the flow path unit 20 will be described in detail with reference to FIGS. 4, the flow path unit 20 has a flow path 21 that allows a fluid to flow in a flow direction extending from an inlet 21a to an outlet 21b along an axis X, a recess 22 having a flow path diaphragm 22a disposed at the bottom thereof, and a communication hole 23 that extends cylindrically along a second axis Y2 perpendicular to the axis X. The communication hole 23 is in communication with the flow path 21.

[0048] The flow path diaphragm 22a is a diaphragm formed in a thin film shape from a corrosion-resistant material (for example, PC (polycarbonate)). The flow path diaphragm 22a is a member formed in a circular shape in a plan view with the second axis Y2 as the central axis, and its outer peripheral edge portion is joined to the flow path main body 20A by adhesion or welding so as to close the communication hole 23. Therefore, the fluid introduced into the flow path 21 does not flow out from the flow path 21 to the outside. Since the flow path diaphragm 22a is formed in a thin film shape, it is displaced along the first axis Y1 by the pressure of the fluid introduced into the flow path 21.

[0049] 3 is removed from the pressure detection unit 10, the flow path diaphragm 22a of the flow path unit 20 is spaced apart from the sensor rod 12aC of the pressure detection unit 10. On the other hand, in a state in which the flow path unit 20 is attached to the pressure detection unit 10 as shown in Fig. 10 described later, the flow path diaphragm 22a of the flow path unit 20 is in contact with the sensor rod 12aC of the pressure detection unit 10. Therefore, the flow path diaphragm 22a serves as a surface for transmitting the pressure of the fluid flowing through the flow path 21 to the sensor rod 12aC.

[0050] 4, when the flow path unit 20 is not attached to the pressure detection unit 10, the flow path diaphragm 22a is exposed to the outside. However, since the flow path diaphragm 22a is disposed at the bottom of the recess 22, there is little risk that an operator will touch the flow path diaphragm 22a.

[0051] 4, an endless annular groove 22b extending around the second axis Y2 is formed on the outer circumferential surface of the recess 22 of the passage unit 20. Meanwhile, an endless annular protrusion 30a extending around the second axis Y2 is formed on the mounting portion 30. The mounting portion 30 made of an elastically deformable material (e.g., a resin material) is pressed toward the annular groove 22b formed on the outer circumferential surface of the recess 22, whereby the annular protrusion 30a is engaged with the annular groove 22b.

[0052] 4, when the annular protrusion 30a is engaged with the annular groove 22b, a minute gap is provided between the outer circumferential surface of the annular protrusion 30a and the inner circumferential surface of the annular groove 22b. Therefore, when the mounting part 30 is attached to the pressure detection unit 10, it is rotatable about the second axis Y2 relative to the sensor part 12 and the holding part 13. This allows the operator to rotate the mounting part 30 about the second axis Y2 with the pressure detection unit 10 fixed to the installation surface S.

[0053] 3, the attachment portion 30 is a member formed in a cylindrical shape extending along the second axis Y2, and has a connecting member 31 and a knob portion 32. The attachment portion 30 is attached to the flow path unit 20 so as to be rotatable about the second axis Y2. As shown in FIGS. 3 and 4, the connecting member 31 has a groove portion 31a that accommodates the protrusion portion 13aB protruding from the main body portion 13a of the holding portion 13.

[0054] The groove portion 31a has a first groove portion 31aA that extends along the second axis Y2 and has an open lower end, and a second groove portion 31aB that is connected to the upper end of the first groove portion 31aA and extends in the circumferential direction around the axis Y. The second groove portion 31aB has a recess 31aC formed in a shape corresponding to the outer circumferential surface of the protrusion 13aB at the other end opposite to the one end connected to the first groove portion 31aA in the circumferential direction. The second groove portion 31aB is formed in a range of less than one rotation around the axis Y from the one end connected to the first groove portion 31aA to the other end where the recess 31aC is formed. This range is preferably, for example, a range of 1 / 4 rotation or less (a range of a rotation angle of 45 degrees or less).

[0055] The connecting member 31 has an accommodation hole 31d for accommodating the flow path main body 20A of the flow path unit 20. The accommodation hole 31d is formed with a predetermined opening width in the circumferential direction so that the flow path main body 20A is rotatable about the second axis Y2 with respect to the connecting member 31. After the flow path unit 20 is placed in the accommodation hole 31d of the connecting member 31, a knob portion 32 is attached to the upper end of the connecting member 31, so that the flow path unit 20 is accommodated in the accommodation hole 31d.

[0056] The knob portion 32 is a member that extends in a direction perpendicular to the second axis Y2 and allows the operator to apply a pressing force in a direction along the second axis Y2 against the biasing force generated by the biasing portion 14. In addition, the knob portion 32 is a member that allows the operator to apply a force that rotates the attachment portion 30 in the circumferential direction about the second axis Y2.

[0057] Next, an operation for attaching the flow passage unit 20 to the pressure detection unit 10 will be described. When attaching the flow passage unit 20 to the pressure detection unit 10 attached to the installation surface S, the operator performs the work in the following procedure.

[0058] First, as shown in FIG. 3, the first axis Y1 of the pressure detection unit 10 and the second axis Y2 of the flow path unit 20 are aligned, and the flow path unit 20 is positioned so that the circumferential position of the protrusion portion 13aB of the pressure detection unit 10 about the first axis Y1 and the circumferential position of the first groove portion 31aA of the mounting portion 30 about the second axis Y2 are aligned.

[0059] 3, the operator moves the flow path unit 20 downward along the second axis Y2, and inserts the sensor portion 12 of the pressure detection unit 10 into the recess 22 of the flow path unit 20. When the sensor portion 12 is inserted into the recess 22, the sensor rod 12aC of the sensor portion 12 comes into contact with the flow path diaphragm 22a of the flow path unit 20.

[0060] 6, in a state where the sensor rod 12aC is in contact with the flow path diaphragm 22a, the protrusion 13aB of the pressure detection unit 10 is inserted into the first groove 31aA of the attachment part 30. In a state where the operator is not applying a pressing force to press the knob part 32 downward, the biasing part 14 generates a biasing force that supports the weight of the attachment part 30 and the flow path unit 20.

[0061] Next, while holding the knob portion 32 in the state shown in Fig. 6, the operator applies a pressing force to press the mounting portion 30 downward. When a downward pressing force is applied to the mounting portion 30, the spring 14a of the biasing portion 14 contracts, and the protrusion 13aB of the pressure detection unit 10 reaches the upper end of the first groove portion 31aA. With the protrusion 13aB reaching the upper end of the first groove portion 31aA, the operator rotates the knob portion 32 clockwise along the circumferential direction about the axis Y, and inserts the protrusion 13aB into the second groove portion 31aB, resulting in the state shown in Fig. 7.

[0062] Fig. 7 is a front view showing the pressure detection device 100 in a state in which the mounting portion 30 is being rotated from the release position to the lock position. In the state shown in Fig. 7, even if the operator reduces the force pressing the knob portion 32 downward or releases the knob portion 32, the mounting portion 30 to which the upward biasing force is applied by the biasing portion 14 is restricted from moving upward toward the first axis line Y1. This is because even if the mounting portion 30 tries to move upward due to the biasing force of the biasing portion 14, the second groove portion 31aB comes into contact with the protrusion portion 13aB.

[0063] Next, while gripping the knob portion 32 in the state shown in Fig. 7, the operator rotates the knob portion 32 clockwise along the circumferential direction about the second axis Y2, and presses the recess 31aC arranged at the end of the second groove portion 31aB against the protrusion 13aB, resulting in the state shown in Fig. 8. As shown in Fig. 8, the recess 31aC is recessed downward along the first axis Y1 more than the second groove portion 31aB, and is formed in a shape corresponding to the outer circumferential surface of the protrusion 13aB.

[0064] Fig. 8 is a front view showing the pressure detection device 100 in a state in which the mounting portion 30 is rotated to the lock position. Fig. 9 is a plan view of the pressure detection device 100 shown in Fig. 8. Fig. 10 is a vertical cross-sectional view of the pressure detection device 100 shown in Fig. 8.

[0065] As shown in Figure 8, when the mounting portion 30 is rotated to the locked position, the biasing force generated by the biasing portion 14 presses the recess 31aC of the second groove portion 31aB against the protrusion portion 13aB, thereby positioning the sensor portion 12 at a predetermined position on the second axis Y2.

[0066] Furthermore, the mounting portion 30 restricts rotation about the second axis Y2 by pressing the recess 31aC against the protrusion 13aB with the biasing force generated by the biasing portion 14. This is because, when the recess 31aC is pressed against the protrusion 13aB, the knob portion 32 cannot be rotated counterclockwise unless the operator applies a pressing force that presses the knob portion 32 downward.

[0067] In the above, the operation of attaching the flow passage unit 20 to the pressure detection unit 10 by rotating the attachment portion 30 from the release position to the lock position has been described. The operation of removing the flow passage unit 20 from the pressure detection unit 10 is the operation of rotating the attachment portion 30 from the lock position to the release position.

[0068] When removing the flow path unit 20 from the pressure detection unit 10, the operator presses the knob portion 32 downward to separate the recess 31aC from the protrusion 13aB, and rotates the knob portion 32 counterclockwise to the state shown in Fig. 7. The operator further rotates the knob portion 32 counterclockwise to the state shown in Fig. 6. Thereafter, the operator pulls the attachment portion 30 upward while holding the knob portion 32, thereby separating the flow path unit 20 from the pressure detection unit 10.

[0069] Next, a structure for transmitting the pressure of the fluid from the flow path diaphragm 22a to the pressure detection diaphragm 12aA will be described with reference to Fig. 11 to Fig. 14. Fig. 11 is a partially enlarged view of part A of the pressure detection device 100 shown in Fig. 10, showing a state in which the pressure detection diaphragm 12aA is not pressurized. Fig. 12 is a cross-sectional view of the pressure detection device 100 shown in Fig. 11 taken along the arrow BB.

[0070] Fig. 13 is a diagram showing a Wheatstone bridge circuit formed by connecting four strain resistors with metal wiring. Fig. 14 is a partially enlarged view of part A of the pressure detection device shown in Fig. 10, showing the pressure detection diaphragm 12aA in a pressurized state. Fig. 14 shows the pressure detection diaphragm 12aA and the flow path diaphragm 22a in a state where the pressure detection diaphragm 12aA is not pressurized, by imaginary lines.

[0071] The state in which the pressure-detecting diaphragm 12aA is not pressurized refers to a state in which no fluid flows through the flow path 21 and the flow path 21 is maintained at atmospheric pressure, or a state in which the pressure of the fluid flowing through the flow path 21 is equal to atmospheric pressure. The state in which the pressure-detecting diaphragm 12aA is pressurized refers to a state in which the pressure of the fluid flowing through the flow path 21 is higher than atmospheric pressure.

[0072] 11 and 14, the sensor rod 12aC of the sensor body 12a is a member disposed at the center CP of the first surface 12aA1 of the pressure-detecting diaphragm 12aA. The sensor rod 12aC protrudes toward the flow path diaphragm 22a of the flow path unit 20 along a first axis Y1 perpendicular to the pressure-detecting diaphragm 12aA, and has a tip surface 12aC1 perpendicular to the first axis Y1. The sensor rod 12aC is made of, for example, glass, and is bonded to the center CP of the pressure-detecting diaphragm 12aA by an adhesive.

[0073] The reason why the sensor rod 12aC is made of glass is that it has mechanical and thermal properties equivalent to those of the material (e.g., sapphire) forming the pressure-detecting diaphragm 12aA. By making the mechanical and thermal properties of the sensor rod 12aC equivalent to those of the pressure-detecting diaphragm 12aA, it is possible to suppress a decrease in detection accuracy caused by the mechanical and thermal properties of the sensor rod 12aC when they are different.

[0074] In addition, by using the same material for the sensor rod 12aC and the pressure-detecting diaphragm 12aA, the adhesiveness of both can be improved. The sensor rod 12aC and the pressure-detecting diaphragm 12aA may be formed from the same material or the same type of glass and joined together with an adhesive. The sensor rod 12aC and the pressure-detecting diaphragm 12aA may also be integrally formed from the same material.

[0075] As shown in Figures 11 and 14, when the flow path unit 20 is attached to the pressure detection unit 10 by the mounting portion 30, the displacement of the flow path diaphragm 22a in contact with the tip surface 12aC1 of the sensor rod 12aC is transmitted to the pressure detection diaphragm 12aA via the sensor rod 12aC.

[0076] 11 and 14, the end of the housing member 12b on the flow path unit 20 side comes into contact with the second region R2 on the outer periphery side of the first region R1, with the first region R1 including the center CP of the pressure-detecting diaphragm 12aA being exposed. As shown in Fig. 12, the first region R1 is a circular region centered on the first axis Y1, and the second region R2 is an annular region centered on the first axis Y1.

[0077] 11 and 14, the housing member 12b has a contact surface 12bC that comes into contact with an end region of the flow path diaphragm 22a when the flow path unit 20 is attached to the pressure detection unit 10 by the attachment portion 30. The flow path diaphragm 22a comes into contact with the contact surface 12bC, whereby the position on the first axis Y1 is fixed relatively to the pressure-detecting diaphragm 12aA.

[0078] 11, the length from the first surface 12aA1 to the tip surface 12aC1 of the pressure-detecting diaphragm 12aA along the first axis Y1 is a first length L1, and the length from the first surface 12aA1 to the contact surface 12bC along the first axis Y1 is a second length L2. The first length L1 is set to be 1.0 to 1.3 times the second length L2.

[0079] 11, the sensor rod 12aC has an outer diameter D1, and the communication hole 23 has an inner diameter D2. The outer diameter D1 is set to be 0.2 to 0.6 times the inner diameter D2. The opening hole 12aB1 formed in the base portion 12aB of the sensor body 12a has an inner diameter D3. The outer diameter D1 is set to be 0.2 to 0.5 times the inner diameter D3.

[0080] 11 and 14, an annular protrusion 12bD is formed at the tip of the housing member 12b, protruding toward the flow path unit 20 side beyond the contact surface 12bC. The annular protrusion 12bD is formed in an annular shape around the first axis Y1. An annular groove 24 is formed at a position of the flow path main body 20A facing the annular protrusion 12bD. The width of the annular groove 24 (the length in the direction perpendicular to the second axis Y2) is slightly wider than the width of the annular protrusion 12bD.

[0081] When the sensor part 12 is biased by the biasing part 14 in a direction approaching the flow path unit 20, before the flow path diaphragm 22a contacts the tip surface 12aC1 of the sensor rod 12aC, the annular protrusion 12bD is inserted into the annular groove 24. By inserting the annular protrusion 12bD into the annular groove 24, the first axis Y1 of the pressure detection unit 10 and the second axis Y2 of the flow path unit 20 are aligned with each other.

[0082] Therefore, when the flow path diaphragm 22a contacts the tip surface 12aC1 of the sensor rod 12aC, the first axis Y1 of the pressure detection unit 10 and the second axis Y2 of the flow path unit 20 are aligned. This prevents the flow path diaphragm 22a and the tip surface 12aC1 from shifting in a direction perpendicular to the first axis Y1 after the flow path diaphragm 22a contacts the tip surface 12aC1 of the sensor rod 12aC, thereby preventing fluctuations in the pressure detection characteristics.

[0083] Here, the strain resistance portion 12aD joined to the second surface 12aA2 of the pressure-detecting diaphragm 12aA will be described. Since Fig. 12 is a view of the pressure-detecting diaphragm 12aA seen from the first surface 12aA1 side, the four strain resistance portions 12aD (12aD1, 12aD2, 12aD3, 12aD4) joined to the second surface 12aA2 of the pressure-detecting diaphragm 12aA are shown by virtual lines.

[0084] As shown in FIG. 12, the strain resistance section 12aD1 has two elements, a strain resistance element 12aD11 and a strain resistance element 12aD12, arranged at different positions in the circumferential direction around the center CP. Similarly, the strain resistance section 12aD2 has two elements, a strain resistance element 12aD21 and a strain resistance element 12aD22, arranged at different positions in the circumferential direction around the center CP. Similarly, the strain resistance section 12aD3 has two elements, a strain resistance element 12aD31 and a strain resistance element 12aD32, arranged at different positions in the circumferential direction around the center CP. Similarly, the strain resistance section 12aD4 has two elements, a strain resistance element 12aD41 and a strain resistance element 12aD42, arranged at different positions in the circumferential direction around the center CP.

[0085] As shown in Fig. 12, the four strain resistance parts 12aD of this embodiment are arranged in the first region R1 of the second surface 12aA2 of the pressure-detecting diaphragm 12aA, except for the center CP where the sensor rod 12aC is arranged. The four strain resistance parts 12aD are arranged in the region except for the center CP because the center CP is hardly displaced even when pressure is transmitted from the sensor rod 12aC to the pressure-detecting diaphragm 12aA. The reason why the center CP is hardly displaced is because the center CP of the second surface 12aA2 of the pressure-detecting diaphragm 12aA is bonded to the sensor rod 12aC with an adhesive.

[0086] 13, the resistance values ​​of the four strain resistance sections 12aD change due to the displacement (strain) of the pressure-detecting diaphragm 12aA caused by the pressure transmitted to the pressure-detecting diaphragm 12aA. When pressure is transmitted to the pressure-detecting diaphragm 12aA and the resistance values ​​of the four strain resistance sections 12aD change, the value of the output voltage Vout relative to the input voltage Vin changes. The value of this output voltage Vout is converted into the pressure of the fluid by the sensor substrate 15.

[0087] The functions 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 this embodiment, the flow path unit 20 is detachably attached to the pressure detection unit 10, so that when changing the fluid flowing through the flow path 21, the used flow path unit 20 can be removed from the pressure detection unit 10 and an unused flow path unit 20 can be newly attached to the pressure detection unit 10. Therefore, when changing the fluid flowing through the flow path 21, a time-consuming flow path cleaning operation is not required, and the speed of the operation can be improved. In addition, since an unused flow path unit 20 can be newly used, safety can be improved.

[0088] Furthermore, according to the pressure detection device 100 of this embodiment, when the flow path unit 20 is attached to the pressure detection unit 10 by the mounting portion 30, the displacement of the flow path diaphragm 22a, which is in contact with the tip surface 12aC1 of the sensor rod 12aC arranged at the center CP of the first surface 12aA1 of the pressure detection diaphragm 12aA, is transmitted to the pressure detection diaphragm 12aA via the sensor rod 12aC.

[0089] Since the area of ​​the flow path diaphragm 22a that contacts the tip surface 12aC1 of the sensor rod 12aC is a portion of the entire area of ​​the flow path diaphragm 22a, the entire area of ​​the tip surface 12aC1 of the sensor rod 12aC reliably contacts the flow path diaphragm 22a even if there is an individual difference in the shape of the flow path unit 20 or a variation in the work when attaching the flow path unit 20 to the pressure detection unit 10. Therefore, it is possible to suppress the occurrence of fluctuations in the pressure detection characteristics of the pressure detection unit 10 due to the individual difference in the shape of the flow path unit 20 or a variation in the work when attaching the flow path unit 20 to the pressure detection unit 10.

[0090] Furthermore, according to the pressure detection device 100 of this embodiment, since the pressure detection unit 10 has the sensor rod 12aC disposed at the center CP of the first surface 12aA1 of the pressure detection diaphragm 12aA, the shape of the sensor rod 12aC does not change even when the flow passage unit 20 is replaced. Therefore, compared to the case where the sensor rod 12aC is provided in the flow passage unit 20, it is possible to prevent fluctuations in pressure detection characteristics due to individual differences in the shape of the sensor rod 12aC.

[0091] Here, the fluctuation of the pressure detection characteristics refers to, for example, when an external force is applied to the pressure detection device 100, a change in the pressure detection value before the external force is applied and a change in the pressure detection value after the external force is applied even if the fluid pressure is constant. Also, the fluctuation of the pressure detection characteristics refers to, for example, a change in the pressure detection value when the fluid pressure is gradually increasing and a change in the pressure detection value when the fluid pressure is gradually decreasing even if the fluid pressure is the same.

[0092] Moreover, according to the pressure detection device 100 of this embodiment, the first length L1 along the first axis Y1 from the first surface 12aA1 of the pressure detection diaphragm 12aA to the tip surface 12aC1 of the sensor rod 12aC is 1.0 times or more the second length L2 from the first surface 12aA1 to the contact surface 12bC of the housing member 12b. Therefore, the tip surface 12aC1 of the sensor rod 12aC is disposed at the same position as the contact surface 12bC of the housing member 12b or at a position protruding further toward the flow path diaphragm 22a, and the entire area of ​​the tip surface 12aC1 can be reliably brought into contact with the flow path diaphragm 22a.

[0093] Moreover, according to the pressure detection device 100 of this embodiment, the first length L1 is equal to or less than 1.3 times the second length, so that the tip surface 12aC1 of the sensor rod 12aC is prevented from excessively protruding from the contact surface 12bC of the housing member 12b toward the flow path diaphragm 22a, and fluctuations in the pressure detection characteristics due to excessive deformation of the flow path diaphragm 22a can be prevented.

[0094] Moreover, according to the pressure detection device 100 of this embodiment, the four strain resistance parts 12aD are joined to the area excluding the center CP of the second surface 12aA2 of the pressure detection diaphragm 12aA. Therefore, it is possible to suppress the deterioration of the pressure detection accuracy compared to the case where the strain resistance parts 12aD are arranged at the center CP of the pressure detection diaphragm 12aA, where the displacement is suppressed by the arrangement of the sensor rod 12aC.

[0095] Furthermore, according to the pressure detection device 100 of this embodiment, the outer diameter D1 of the sensor rod 12aC is 0.2 times or more the inner diameter D2 of the communication hole 23 of the flow path unit 20. Therefore, the outer diameter D1 of the sensor rod 12aC relative to the inner diameter D2 of the communication hole 23 is sufficiently secured, and the pressure change of the fluid flowing through the flow path 21 can be reliably transmitted to the pressure-detecting diaphragm 12aA.

[0096] Moreover, according to the pressure detection device 100 of this embodiment, the outer diameter D1 of the sensor rod 12aC is equal to or smaller than 0.6 times the inner diameter D2 of the communication hole 23 of the flow passage unit 20. Therefore, even if there are individual differences in the shape of the flow passage unit 20 or variations in the work for attaching the flow passage unit 20 to the pressure detection unit, the entire area of ​​the tip end surface 12aC1 of the sensor rod 12aC can be reliably brought into contact with the flow passage diaphragm 22a.

[0097] According to the pressure detection device 100 of this embodiment, the outer diameter D1 of the sensor rod 12aC is 0.2 times or more the inner diameter D3 of the opening hole 12aB1 of the base portion 12aB. Therefore, the outer diameter D1 of the sensor rod 12aC relative to the inner diameter D3 of the opening hole 12aB1 is sufficiently secured, and the pressure detection diaphragm 12aA can be reliably displaced according to the pressure transmitted from the sensor rod 12aC.

[0098] Furthermore, according to the pressure detection device 100 of this embodiment, the outer diameter D1 of the sensor rod 12aC is equal to or smaller than 0.5 times the inner diameter D3 of the opening hole 12aB1 of the base portion 12aB. Therefore, the area of ​​the pressure detection diaphragm 12aA where the sensor rod 12aC is not disposed can be sufficiently secured, and the amount of displacement of the pressure detection diaphragm 12aA can be sufficiently secured. [Explanation of symbols]

[0099] 10 Pressure detection unit 11 Main body 12 Sensor section 12a Sensor body 12aA Pressure sensing diaphragm 12aA1 1st page 12aA2 2nd side 12aB Base section 12aB1 Opening hole 12aC Sensor rod (pressure transmission component) 12aC1 Tip surface 12aD distortion resistance section 12b Storage member 12bC contact surface 12bD Annular protrusion 12c Support member 13 Holding part 14. Pressurizing section 15 Sensor board 16 Zero point adjustment switch 18 Guide member 20 Flow path unit 20A Flow path body 21 Flow Path 22 Recess 22a Flow path diaphragm 22b Annular groove 23 Communication hole 24 Annular groove 30 Mounting part 32 Knob 100 Pressure detection device CP center R1 1st area R2 2nd area X axis Y1 1st axis Y2 Second axis

Claims

1. a pressure detection unit for detecting a pressure of the fluid; a flow path unit in which a flow path through which the fluid flows is formed; a mounting portion that detachably mounts the flow passage unit to the pressure detection unit, The flow path unit is a flow path diaphragm that is displaced by the pressure of the fluid flowing through the flow path; The pressure detection unit is a pressure detection diaphragm that is displaced in response to a pressure transmitted from the flow passage unit; a pressure transmitting member that is disposed at a center of a first surface of the pressure detecting diaphragm, that protrudes toward the flow passage unit along a first axis perpendicular to the pressure detecting diaphragm, and that has a tip end surface perpendicular to the first axis; a biasing portion that generates a biasing force that biases the pressure sensing diaphragm toward the flow path diaphragm along the first axis, the attachment portion attaches the flow passage unit to the pressure detection unit in a state in which the tip surface of the pressure transmission member is in contact with the flow passage diaphragm by the biasing force generated by the biasing portion, A pressure detection device in which, with the flow passage unit attached to the pressure detection unit by the mounting portion, the displacement of the flow passage diaphragm in contact with the tip surface is transmitted to the pressure detection diaphragm via the pressure transmission member.

2. A pressure detection unit for detecting a pressure of a fluid; a flow path unit in which a flow path through which the fluid flows is formed; a mounting portion that detachably mounts the flow passage unit to the pressure detection unit, The pressure detection unit includes: a pressure detection diaphragm that is displaced in response to a pressure transmitted from the flow passage unit; a pressure transmitting member that is disposed at a center of a first surface of the pressure detecting diaphragm, that protrudes toward the flow passage unit along a first axis perpendicular to the pressure detecting diaphragm, and that has a tip end surface perpendicular to the first axis; a sensor body including the pressure detection diaphragm, the pressure transmission member, and a base portion to which the pressure detection diaphragm is attached; a housing member that houses the sensor body and contacts a second region on an outer circumferential side of the first region while exposing a first region including the central portion of the pressure-detecting diaphragm, the accommodation member has a contact surface that comes into contact with an end region of the flow path diaphragm when the flow path unit is attached to the pressure detection unit by the attachment portion, a first length along the first axis from the first surface to the tip surface is 1.0 times or more and 1.3 times or less than a second length along the first axis from the first surface to the contact surface, The flow path unit is a flow path diaphragm that is displaced by the pressure of the fluid flowing through the flow path; A pressure detection device in which, with the flow passage unit attached to the pressure detection unit by the mounting portion, the displacement of the flow passage diaphragm in contact with the tip surface is transmitted to the pressure detection diaphragm via the pressure transmission member.

3. the pressure detection unit has four strain resistors joined to a second surface of the pressure detection diaphragm and connected to form a Wheatstone bridge circuit; The pressure detection device according to claim 1 , wherein the four strain resistance portions are joined to an area of ​​the second surface excluding the central portion.

4. the flow passage unit extends cylindrically along a second axis perpendicular to the flow passage and has a communication hole communicating with the flow passage, the communication hole is closed by the flow path diaphragm, 4. The pressure detection device according to claim 1, wherein an outer diameter of the pressure transmitting member is 0.2 to 0.6 times an inner diameter of the communication hole.

5. The base portion has an opening hole extending cylindrically along the first axis, the opening hole is closed by the pressure sensing diaphragm, 3. The pressure detection device according to claim 2, wherein the outer diameter of the pressure transmitting member is 0.2 to 0.5 times the inner diameter of the opening.

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