JP6332655B2 - Hot-wire anemometer and blood anemometer using the same - Google Patents

Description

  The present invention relates to a hot-wire anemometer and a blood anemometer using the same.

  As described in, for example, Patent Document 1, a hot-wire anemometer usually has one of four resistors having a resistance bridge as a wiring cable having a hot wire such as platinum connected to the tip, and the hot wire is flow direction. The flow velocity of the fluid is measured by extending in a direction crossing the direction of the fluid and arranging it in the fluid to generate heat by energization and measuring the resistance change due to the cooling of the hot wire in proportion to the flow velocity of the fluid.

  By the way, a hot-wire anemometer having the above-described configuration is extremely sensitive and can be formed with a very thin outer diameter. For example, a blood flow velocity can be reduced by inserting the catheter into a blood vessel as a catheter probe. It is also possible to measure.

JP 2000-266773 A

  However, if the entire probe is made very thin while maintaining the configuration of the conventional hot-wire anemometer, the wiring cable that passes through the probe and has a hot wire connected to the tip will also become very thin. There arises a problem of high sensitivity as noise.

The present invention advantageously solves the problems of the conventional hot-wire anemometer described above, and the hot-wire anemometer of the present invention connects one of the two resistors on the same pole side of the resistance bridge and a hot wire at the tip. It is necessary to extend the heat wire in a direction crossing the flow direction, place it in the fluid, generate heat by energization, and measure the resistance change due to cooling of the heat wire in proportion to the fluid flow velocity. In a hot-wire anemometer that measures the flow velocity of
The other one of the two resistors on the same pole side of the resistance bridge is extended to the vicinity of the heat wire along the wiring cable having the heat wire connected to the tip, and the tip is closed in a circuit. Including wiring cables ,
A wiring cable in which a heat wire is connected to the tip and a wiring cable in which the tip is closed in a circuit are accommodated in a common sleeve, and the heat wire is projected from the tip of the sleeve. .

The blood flow meter of the present invention includes one of two resistances on the same pole side of the resistance bridge including a wiring cable having a hot wire connected to the tip, and the hot wire extends in a direction crossing the flow direction. In a blood flow meter that measures the blood flow rate by measuring the resistance change due to cooling of the heat ray proportional to the blood flow rate, and placing it in the bloodstream to generate heat,
The other one of the two resistors on the same pole side of the resistance bridge is extended to the vicinity of the heat wire along the wiring cable having the heat wire connected to the tip, and the tip is closed in a circuit. Including wiring cables,
A wiring cable in which a heat wire is connected to the tip and a wiring cable having the tip closed are accommodated in a common sleeve that is inserted into a blood vessel, and the heat wire is disposed so as to protrude in an insulated state from the tip of the sleeve. A catheter type probe is configured.

In such a hot-wire anemometer of the present invention, one of the two resistors on the same pole side out of the four resistors that form a resistance bridge includes a wiring cable having a hot wire connected to the tip. The other one of the two resistances on the same pole side of the resistance bridge is extended to the vicinity of the heating wire along the wiring cable having the heating wire connected to the tip, and the tip is closed in a circuit. A wiring cable having a heat wire connected to the tip and a wiring cable having the tip closed in a circuit are housed in a common sleeve, and the heat wire is projected from the tip of the sleeve. Therefore, the flow rate of the fluid is measured by extending the heat ray in the direction intersecting the flow direction and placing it in the fluid to generate heat by energization and measuring the resistance change due to the cooling of the heat ray proportional to the flow rate of the fluid. When that, because affected by external environment such as a fluid to the same extent with each other and distribution cable side of closing the distribution cable and the tip of the connected side heat rays tip within a common sleeve as noise, the resistance bridge Therefore, those noises are substantially canceled out.

  Therefore, according to the hot-wire anemometer of the present invention, even when the entire probe is formed to be very thin for measuring the flow velocity of the fluid in the thin tube, the influence of noise received by the wiring cable having the hot wire connected to the tip is almost or The flow rate of the fluid can be measured with high accuracy without any loss.

Further, in the blood flow velocity meter according to the present invention, one of the two resistances on the same pole side of the resistance bridge includes a wiring cable in which a heat wire is connected to the tip, and the resistance bridge is assembled. Of the four resistors, the other one of the two resistors on the same pole side is extended to the vicinity of the hot wire along the wiring cable in which the hot wire is connected to the tip. is intended to include wire cables closed, the sleeve the heat ray accommodates the wiring cables and a common wiring cable that connects hot wire into the distal end in the sleeve closing said distal end to be inserted into a blood vessel because from the tip to constitute a catheter probe and arranged to protrude in an insulated state, the hot wire is heated by energization and positioned within the vessel by extending in a direction intersecting the direction of blood flow, proportional to blood flow velocity Heat ray When measuring the blood flow velocity by measuring the resistance change due to retirement, the external environment of the blood stream, such as to the same extent with each other and interconnect cables closed distribution cable and the tip by connecting the hot wire in a common sleeve in the distal end As a result, the noise is substantially canceled in the resistor bridge.

  Therefore, according to the blood flow meter of the present invention, even when a catheter type probe is configured by forming the entire probe to be extremely thin, the influence of noise received by the wiring cable having a hot wire connected to the tip is little or not, The blood flow rate can be measured with high accuracy.

In the blood flow velocity meter according to the present invention , the wiring cable having a hot wire connected to the tip and the wiring cable having the tip closed in a circuit form are twisted wires (twisting wires) that are twisted together. A resistance bridge because the distribution cable that connects the hot wires and the distribution cable that closes the tip are in close contact with each other in the sleeve, and the effects of the external environment such as blood flow that these distribution cables receive are better matched. This is preferable because noises received by the wiring cables can be more effectively offset.

  In the blood flow meter of the present invention, if the wiring cable is a titanium wire coated with a fluororesin such as polytetrafluoroethylene, the wiring cable can move smoothly in the sleeve due to the low friction of the coating. Therefore, it is preferable because the insertion of the catheter probe into the blood vessel becomes smooth and the short circuit between the wiring cables can be prevented by the insulating property of the coating.

(A) is explanatory drawing which shows typically one Embodiment of the hot-wire anemometer of this invention, (b) is explanatory drawing which shows other one Embodiment of the hot-wire anemometer of this invention typically. is there. (A) is explanatory drawing which shows typically one Embodiment of the blood flow rate meter of this invention to which the hot-wire flow rate meter of above-mentioned embodiment was applied, (b) is the catheter type | mold in (a) The side view which expands and shows the A part containing the front-end | tip part of a probe, (c) is the longitudinal cross-sectional view which expands and shows the B part containing the sleeve of the catheter type probe in (a), (d) is this It is explanatory drawing which shows the modification of the blood flow rate meter of embodiment. (A) is a longitudinal sectional view showing an enlarged configuration example of the tip in FIG. 2 (b), (b) is a perspective view showing an enlarged configuration example of the sleeve in FIG. 2 (c), (C) is a longitudinal sectional view showing an enlarged configuration example of the wiring cable in FIG. 2 (c). (A) is a cross-sectional view showing an enlarged arrangement example of the wiring cable in the sleeve in FIG. 2 (c), and (b) is a cross-sectional view showing an enlarged configuration example of the wiring cable. . It is explanatory drawing which shows the circuit structure of the blood flow rate meter of the said embodiment. It is a perspective view which expands and shows the modification of the wiring cable in the sleeve shown in FIG.2 (c).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, FIG. 1A is an explanatory view schematically showing an embodiment of the hot-wire anemometer of the present invention. The hot-wire anemometer of this embodiment includes a resistor R3, which is one of two resistors R3, R4 on the ground side, which is the same pole, among four resistors R1, R2, R3, R4 that form a resistance bridge. The wiring cable C1 having a coiled heat wire HW connected to the tip, that is, the resistance of the heat wire HW and the resistance of the two wiring cables C1 are connected in series, and the heat wire HW protrudes from the tip of the sleeve S and is fixed. The probe P is formed by passing C1 through the sleeve S, and the axial direction of the coil of the heat wire HW is made to coincide with the axial direction of the sleeve S, so that the heat wire HW intersects the fluid flow direction FL indicated by an arrow in the figure. Extending in the direction and arranged in the fluid, heat is generated by energization from the resistance bridge, and the resistance change due to cooling of the hot wire HW proportional to the flow velocity of the fluid is changed to the bridge drive circuit BD. By measuring the current change, and measures the flow velocity of the fluid.

  In particular, in the hot-wire anemometer of this embodiment, among the four resistors R1, R2, R3, and R4 that form a resistance bridge, the other one of the two ground-side resistors R3 and R4 that are the same poles. The resistor R4 is a wiring cable C2 having two ends, which is extended in the sleeve S along the wiring cable C1 having the heat wire HW connected to the tip and close to the heat wire HW, ie, two wires. The resistance of the cable C1 is connected in series. The heat wire HW is, for example, a surface of a platinum wire coated with a thin insulating resin film, and each of the wiring cables C1, C2 is also a thin insulating resin film on the surface of a conductive metal wire such as a copper wire or a titanium wire. Is coated.

  In the hot-wire anemometer of this embodiment, the resistor R3, which is one of the two resistors R3 and R4 on the same pole side of the resistor bridge, includes the wiring cable C1 with the hot wire HW connected to the tip. The resistor R4, which is the other of the two resistors R3 and R4 on the same pole side of the resistor bridge, is extended to the vicinity of the heat wire HW along the wiring cable C1 having the heat wire HW connected to the tip. In addition, since the wiring cable C2 whose end is closed in a circuit manner is included, the heat ray HW extends in a direction intersecting the flow direction, is placed in the fluid and is heated by energization, and the flow velocity of the fluid is measured. In this case, since the wiring cable C1 and the wiring cable C2 are affected by the influence of the external environment such as fluid as noise to change the resistance value, the noise is substantially canceled in the resistance bridge. It is.

  Therefore, according to the hot-wire anemometer of this embodiment, even when the entire probe P is formed very thin for measuring the flow velocity of the fluid in the narrow tube, the noise received by the wiring cable C1 with the hot wire HW connected to the tip. The flow velocity of the fluid can be measured with high accuracy with little or no influence.

  FIG.1 (b) is explanatory drawing which shows typically other embodiment of the hot-wire anemometer of this invention, and in this embodiment, of two wiring cables C1 which connected the hot wire HW to the front-end | tip. One is shared with one of the two wiring cables C2 whose ends are closed in a circuit form, and three wiring cables extending into the sleeve S are formed. The effect of removing the influence of noise can be obtained in the same manner as in the previous embodiment, and according to this embodiment, the number of wiring cables is reduced, so that the sleeve S can be made thinner.

  FIG. 2 (a) is an explanatory view schematically showing an embodiment of the blood flow velocity meter of the present invention to which the hot-wire flow velocity meter of the above embodiment is applied, and FIG. 2 (b) is a diagram in FIG. 2 (a). The side view which expands and shows the A section containing the front-end | tip part of the catheter type probe of FIG. 2, FIG.2 (c) is a longitudinal cross-sectional view which expands and shows the B section containing the sleeve of the catheter type probe in FIG. In the figure, the same parts as those in the previous embodiment are denoted by the same reference numerals.

  That is, as shown in FIG. 5 to be described later, the blood flow meter of this embodiment includes a resistor R3, which is one of the ground sides of the four resistors R1, R2, R3, and R4 that form a resistor bridge. A wiring cable C1 with a hot wire HW connected to the tip and an auxiliary resistor R3 ′ connected in series with it, that is, a resistance of the hot wire HW, a resistance of two wiring cables C1, and an auxiliary resistor R3 ′ are connected in series, and the hot wire HW is blood. The blood flow rate is measured by measuring the resistance change due to cooling of the hot wire HW proportional to the blood flow rate, extending in a direction crossing the flow direction of the blood and placing it in the blood flow in the blood vessel to generate heat when energized. To do.

In this embodiment, in particular, the resistor R4, which is the other one of the four resistors R1, R2, R3, and R4 in the resistance bridge, is connected to the wiring cable C1 having the hot wire HW connected to the tip. A wiring cable C2 having a closed circuit end and an auxiliary resistor (variable resistance in the illustrated example) R4 ′ connected in series to the heat wire HW, that is, the resistance of two wiring cables C1. And the auxiliary resistor R4 ′ are connected in series, and a wiring cable C1 having a heat wire HW connected to the tip and a wiring cable C2 having a closed tip are accommodated in a sleeve S inserted into the blood vessel, and the tip of the sleeve S the arranged to heat rays HW from the tip of the sleeve S is projected in an insulated state by encapsulating the heat ray HW in liquid-tight insulation resin chips rounded tip to seal the T, the catheter-type flop Constitute the over blanking P. The auxiliary resistors R3 ′ and R4 ′ are used for adjusting the equilibrium state of the resistance bridge and setting the resistance values of the resistors R3 and R4.

  3A is a longitudinal sectional view showing an enlarged configuration example of the tip portion in FIG. 2B, and FIG. 3B is an enlarged configuration example of the sleeve in FIG. 2C. FIG. 3C is an enlarged longitudinal sectional view showing a configuration example of the wiring cable in FIG. 2C, and FIG. 4A is a sleeve in FIG. FIG. 4B is an enlarged cross-sectional view showing a configuration example of the wiring cable.

  As shown in FIG. 3A, the hot wire HW in this embodiment is formed by winding a platinum fine wire having a diameter of 10 μm in a coil shape with a gap, for example, and pulling out both ends of the platinum fine wire from one end in the axial direction of the coil. As shown in FIG. 3B, the sleeve S in this embodiment is, for example, a flexible cylindrical shape having an outer diameter of 360 μm and an inner diameter of 200 μm by tightly winding a stainless wire having a diameter of 80 μm in a coil spring shape. As shown in FIG. 3C, each of the wiring cables C1 and C2 is made of, for example, tritetrafluoroethylene (trade name: Teflon) as a fluororesin on the surface of a titanium wire TW having a diameter of 50 μm. A coating TC having a thickness of 10 to 20 μm is applied.

  Here, as shown in FIG. 4 (a), a total of four wiring cables C1 and C2 are housed adjacent to each other in the sleeve S, and at this time, as shown in FIG. 4 (b). If the thickness of the Teflon coating TC is 10 μm, the total diameter of the four wiring cables C1 and C2 is 149 and 9 μm in total, so that the four wiring cables C1 and C2 are free to play in the sleeve S having an inner diameter of 200 μm. In addition, the sleeve S can be freely bent and deformed and inserted to a desired site in the blood vessel without being hindered by friction caused by sliding contact with the wiring cables C1 and C2.

  FIG. 5 is an explanatory diagram showing the circuit configuration of the blood flow meter of the above embodiment. In the blood flow meter of this embodiment, four resistors R1, R2, R3 (= HW + 2C1 + R3 ′), R4 (= 2C2 + R4). ') The resistance change of the above-described resistance bridge due to the cooling of the hot wire HW proportional to the blood flow velocity is measured as a current change by the bridge drive circuit BD, and the analog output signal of the bridge drive circuit BD is measured by the A / D converter. The digital output signal is converted into a digital output signal and input to a central processing unit (CPU). The CPU performs arithmetic processing based on a program in a memory (not shown) to convert the digital output signal into a signal indicating a blood flow rate. Output.

  In this circuit configuration, the portion excluding the hot wire HW and the four wiring cables C1, C2 constituting the catheter probe P is blood fixed to the proximal end portion of the catheter probe P shown in FIG. It is mounted on a printed circuit board in the main body MB of the anemometer, and on the printed circuit board in the main body MB, there are a signal output terminal for outputting a signal indicating the blood flow rate, and a power input terminal for inputting power from outside. Is provided.

  The main body MB itself may be formed as a connector having a signal output terminal and a power input terminal. In this way, the power supply from the outside and the external can be easily connected to the corresponding socket. The signal can be taken out from the signal.

  In the example shown in FIG. 2A, the main body MB is fixed to the proximal end portion of the catheter type probe P. Instead, as shown in FIG. 2D, the proximal end portion of the catheter type probe P is used. The main body MB may be detachably coupled via the connector CN, and the four wiring cables C1 and C2 in the sleeve S may be detachably connected to the printed circuit board in the main body MB via the connector CN. In this way, it is possible to easily replace only the catheter probe P while leaving the main body MB.

  In the blood flow meter of this embodiment, a wiring cable C1 in which a resistance R3, which is one of two resistances R3 and R4 on the ground side, which is the same pole of a resistance bridge, is connected to a hot wire HW at the tip. And the auxiliary resistor R3 ′ connected in series therewith, that is, the resistance of the heat wire HW, the resistance of the two wiring cables C1, and the auxiliary resistor R3 ′, and two resistances on the ground side that are the same pole of the resistance bridge A wiring cable having a closed end in a circuit, in which a resistor R4, which is one of R3 and R4, is extended along the wiring cable C1 having a hot wire HW connected to the tip and close to the hot wire HW. Since the C2 and the auxiliary resistor R4 ′ connected in series with it, that is, the resistance of the two wiring cables C1 and the auxiliary resistor R4 ′ are connected in series, the hot wire HW is connected to the tip in the sleeve S inserted into the blood vessel. The wiring cable C1 and the wiring cable C2 with the distal end closed are accommodated, and the hot wire HW is disposed in an insulated state at the distal end portion of the sleeve S to form the catheter probe P. The hot wire HW intersects the blood flow direction. When the blood flow rate is measured by measuring the change in resistance caused by cooling of the hot wire in proportion to the blood flow rate by extending in the direction and arranging in the blood vessel to generate heat, the distribution cable C1 and the distribution cable C2 Are affected by the influence of the external environment such as blood flow to the same extent as noise, so that these noises are substantially canceled within the resistance bridge.

  Therefore, according to the blood flow meter of this embodiment, even when the entire probe is formed to be thin and the catheter type probe P is configured, the influence of the noise received by the wiring cable C1 having the hot wire HW connected to the tip is almost or not. Without any, the blood flow rate can be measured with high accuracy.

  Furthermore, according to the blood flow meter of this embodiment, since the wiring cables C1 and C2 are titanium wires TW subjected to Teflon coating TC, the wiring cables C1 and C2 are placed in the sleeve S due to the low friction property of the coating TC. Therefore, the catheter type probe P can be smoothly inserted into the blood vessel, and the short circuit between the wiring cables C1 and C2 can be prevented by the insulating property of the coating TC. According to the blood flow meter of this embodiment, since the sleeve S is made of a coil spring-like stainless steel wire, the flexibility of the sleeve S facilitates the insertion of the catheter probe P into the blood vessel, and the sleeve S Corrosion resistance of S can also prevent corrosion of the probe P with blood.

  FIG. 6 is an enlarged perspective view showing a modification of the wiring cable in the sleeve S shown in FIG. 2C. In this modification, the four wiring cables C1 and C2 in the sleeve S are twisted. It is a line. According to this modified example, the distribution cable C1 with the leading end connected to the heat wire and the distribution cable C2 with the closed end are in close contact with each other in the sleeve S, and the external environment such as blood flow received by the distribution cables C1 and C2 Thus, the influence of the noises can be better matched and the noise received by the wiring cable in the resistance bridge can be more effectively offset. Note that the configuration in which the wiring cables C1 and C2 are twisted wires (twisting wires) can also be applied to the hot-wire anemometer of the previous embodiment shown in FIG.

  As mentioned above, although demonstrated based on the example of illustration, this invention is not limited to the above-mentioned example, It can change suitably within the description range of a claim, For example, the hot-wire anemometer of this invention is, for example, It can also be used for direct measurement of the flow velocity of fluid in a narrow tube such as a cooling tube in a radiator core.

  In the blood flow meter of the present invention, for example, the shape of the insulating resin tip T at the tip of the catheter probe P is set so that the blood flow passes through the coil of the hot wire HW or around the spiral hot wire HW. In addition, it may be formed in a cylindrical shape having an opening at the front end portion and the outer peripheral portion. As shown in FIG. 1B, one of the two wiring cables C1 is replaced with two wiring cables. Three wiring cables extending in the sleeve S may be used in common with one of C2.

  Furthermore, in the blood flow meter of the present invention, for example, one or a plurality of deflection wires are arranged along the distribution cables C1 and C2 in the sleeve S of the catheter probe P, and the deflection wires By connecting the distal end to the distal end of the sleeve S and enabling the proximal end to be pushed and pulled with a handle, lever, etc., the orientation of the distal end of the catheter-type probe P in the blood vessel is changed to follow the blood vessel. It may be possible.

  Further, in each of the above embodiments, one of the two resistors R3 and R4 on the ground (negative electrode) side as the same pole side is assumed to include a wiring cable having a heat wire connected to the tip, and the other one to the tip. Including the wiring cable with the circuit closed at the tip, extending to the vicinity of the heating wire along the wiring cable connected with the heating wire, in the heating wire velocimeter and blood flow velocity meter of the present invention, One of the two resistances R1 and R2 on the positive electrode side as the same pole side is assumed to include a wiring cable with a hot wire connected to the tip, and the other one along the wiring cable with a hot wire connected to the tip. It may include a wiring cable that extends to the vicinity of the heat wire and has a closed circuit end, or a combination thereof.

  And in the hot-wire anemometer and blood anemometer of this invention, the constituent material of each member is not limited to the thing in the said embodiment, It can change suitably as needed.

  Thus, according to the hot-wire anemometer of the present invention, even when the entire probe is formed to be very thin for measuring the flow velocity of the fluid in the narrow tube, the influence of the noise received by the wiring cable having the hot wire connected to the tip is little or not. Without it, the flow rate of the fluid can be measured with high accuracy.

  Further, according to the blood flow meter of the present invention of the present invention, even when a catheter type probe is configured by forming the entire probe to be very thin, the influence of noise received by the wiring cable having a hot wire connected to the tip is almost or not. Without it, the blood flow rate can be measured with high accuracy.

C1, C2 Wiring cable CN Connector FL Flow direction HW Heat wire MB Body P Probe R1-R4 Resistance R3 ', R4' Auxiliary resistance S Sleeve TC Teflon coating TW Titanium wire

Claims (4)

One of the two resistors on the same pole side of the resistance bridge includes a wiring cable with a hot wire connected to the tip, and the heat wire is extended in the direction crossing the flow direction and placed in the fluid to energize In a hot-wire anemometer that measures the flow velocity of the fluid by measuring the resistance change due to the cooling of the hot wire proportional to the flow velocity of the fluid,
The other one of the two resistors on the same pole side of the resistance bridge is extended to the vicinity of the heat wire along the wiring cable having the heat wire connected to the tip, and the tip is closed in a circuit. Including wiring cables ,
A hot wire velocimeter characterized in that a wiring cable having a hot wire connected to the tip and a wiring cable having the tip closed in a circuit are accommodated in a common sleeve, and the hot wire is projected from the tip of the sleeve. . One of the two resistors on the same pole side of the resistance bridge shall include a wiring cable with a hot wire connected to the tip, and the hot wire extends in the direction crossing the flow direction and is placed in the bloodstream. In a blood flow meter that measures the blood flow rate by measuring the resistance change due to cooling of the heat ray proportional to the blood flow rate,
The other one of the two resistors on the same pole side of the resistance bridge is extended to the vicinity of the heat wire along the wiring cable having the heat wire connected to the tip, and the tip is closed in a circuit. Including wiring cables,
A catheter type in which a wiring cable in which a heat wire is connected to the distal end and a wiring cable having the distal end closed are accommodated in a sleeve inserted into a blood vessel, and the heat wire protrudes in an insulated state from the distal end of the sleeve. A blood flow meter comprising a probe. The blood flow meter according to claim 1 or 2, wherein the wiring cable having a hot wire connected to the tip and the wiring cable having the tip closed in a circuit form are twisted wires that are twisted together . The distribution cable, according to claim 1 or 2 blood flow velocity meter, wherein the coating of the fluororesin is titanium lines into force a.

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