JP3032639B2 - Constant speed exhaust valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant-speed exhaust valve for constant-speed exhaust performed when measuring a blood pressure of a sphygmomanometer.

[0002]

2. Description of the Related Art A sphygmomanometer for measuring blood pressure by an oscillometric method is a method in which a cuff wound on an upper arm or the like is pressurized to a predetermined pressure by an air pump to compress an artery, thereby temporarily stopping blood flow, and then controlling the pressure in the cuff. Is gradually lowered by a constant-speed exhaust valve, and during this time, the pattern of the cuff internal pressure and vibration amplitude associated with arterial pulsation is processed by a microcomputer,
Peak and diastolic blood pressure values are measured. The constant speed exhaust valve used in such a sphygmomanometer has a cuff internal pressure of 3 to 3.
What can be lowered linearly with time at a constant speed of about 4 mmHg / sec is desired.

FIGS. 4 and 5 show a conventional example of a constant speed exhaust valve. The constant-speed exhaust valve shown in FIG.
The constant-speed exhaust valve shown in FIG. 5 and the constant-speed exhaust valve shown in FIG. 5 are those disclosed in JP-A-57-14321. A pressure member (adjustment screw) for adjusting the opening amount of the slit 21 is formed on the side of the opening of the valve body 2 where the flange 22 is formed.
The exhaust is performed from the outer surface of the valve body 2 through the slit 21 and the cylindrical pressing member 4.

Incidentally, the characteristic of the exhaust air amount Q (cc / min) with respect to the constant speed exhaust valve pressure P (mmHg) necessary to obtain a desired pressure drop speed of the cuff, that is, the so-called PQ characteristic, is theoretical. 6, the exponential curve must be drawn such that the degree of increase in the exhaust air amount Q increases as the pressure P decreases. Here, in the valve body 2 of the above-described conventional example, when the pressure P is high, the valve body 2 made of an elastic body receives a strong compressive force from the outer peripheral surface and the opening amount of the slit 21 is reduced, so that the valve body 2 is exhausted from the opening. Air volume is reduced,
When the pressure P decreases and the compression force received by the valve element 2 from the pressure P decreases, the slit 21 increases due to the restoring force of the elasticity of the valve element 2 itself, and the displacement Q increases. It has a PQ characteristic similar to (a). However, if the pressure P becomes smaller than a certain value, the opening amount of the slit 21 does not change even when the pressure P decreases, so that the relationship between the pressure P and the exhaust amount Q under a constant opening amount is the same. Thus, a curve indicated by b in FIG. 6 is drawn, and the pressure P is low, and thus greatly deviates from the theoretical value, but the influence on the blood pressure measurement is small. Therefore, the constant-speed exhaust valve shown in the above-mentioned conventional example has a simple structure,
This is preferable as a constant speed exhaust valve.

[0005]

However, there are actually the following problems. That is, the valve body 2 having a closed-end cylindrical shape or a cup shape and having one end closed is formed by molding using an upper mold and a lower mold. Since the thickness of the side wall is determined by the relative positional relationship between the upper mold and the lower mold, there is a great possibility that the thickness of the side wall may be uneven at each portion. This is especially true when molding the valve body 2 because a large number of moldings are generally performed using a single mold.

In the valve body 2 in which the slit 21 is provided on the side wall having such an uneven thickness, the opening amount greatly differs even when the same pressure P is applied, depending on the thickness of the portion where the slit 21 is provided. Therefore, the valve 2
7, the PQ characteristic is greatly different from that in the case where there is no uneven thickness (c), as shown in FIG. In the figure, (d) shows a case where the slit 21 is formed in a thin portion of the valve body 2 having an uneven thickness, and E shows a slit 21 formed in a thick portion of the valve body 2 having an uneven thickness. Shows the case where

Therefore, in the constant-speed exhaust valve incorporating the valve body 2 having an uneven thickness, the pressure drop speed of the cuff greatly deviates from the target value, and the pressing member 4 applies an axial force to the valve body 2. As a result, it may not be possible to set the predetermined pressure drop speed even by adjusting the opening amount of the slit 21 to increase or decrease, and the yield during manufacturing is poor.

In the above-described adjustment by the pressing member 4 formed as an adjusting screw, the pressing member 4 shown in FIG. 4, that is, the one in which the tip of the pressing member 4 is in contact with the opening of the valve body 2, Since the change in the tightening amount of the member 4 directly changes the force applied to the valve body 2, even if the pressing member 4 is slightly moved, the opening amount of the slit 21 greatly changes, and it is difficult to perform a fine adjustment operation. It is. In FIG. 5, since the pressing member 4 presses the entire opening surface side of the valve body 2, the change in the opening amount of the slit 21 with respect to the change in the tightening amount of the pressing member 4 is shown in FIG. Although it is gentler than the one, the outer peripheral surface of the flange 22 of the valve body 2 which is in contact with and seals the inner wall of the case 1 moves while rubbing the inner wall of the case 1 at this time. Since the compressive force received by the flange 22 from the inner wall varies depending on the unevenness of the surface of the inner wall, the compression force is not uniform over the entire circumference. Therefore, the flange 22 is deformed, and this deformation affects the opening amount of the slit 21. The correlation between the tightening amount of the pressing member 4 and the opening amount of the slit 21 is not constant, and it is difficult to adjust the opening amount.

[0009]

Further, the fact that the pressing member 4 is an adjusting screw means that when the pressing member 4 is turned and tightened, the valve body 2 receives a torsional force in the rotational direction, and the valve body 2 is twisted and the slit 21 is turned. The opening of the opening becomes distorted and adjustment becomes difficult. The present invention has been made in view of such a point, and it is an object of the present invention to provide a constant-speed exhaust valve having a constant exhaust speed and a good yield during manufacturing. An object of the present invention is to provide a constant-speed exhaust valve capable of easily and accurately adjusting a predetermined exhaust speed.

[0011]

According to the present invention, there is provided a valve body which is formed of an elastic body and has a slit for changing an opening amount in accordance with a fluid pressure applied to an outer surface of the valve body. In a constant-speed exhaust valve provided with a pressing member for adjusting the opening amount of the slit, a compressive force is applied in the axial direction by the pressing member, and the valve body provided with the slit on the side wall has a cylindrical shape having both ends opened. It has some main features.

[0012]

According to the present invention, since the valve body has a cylindrical shape with both ends open, both the inner surface and the outer surface can be determined by only one mold at the time of molding. Problems caused by uneven thickness can be reduced. The pressing member preferably includes an adjusting screw and a spring interposed between the valve body and the adjusting screw. By selecting the spring constant, the compression force applied to the valve element can be moved away from a state where it is uniquely determined by the screw pitch. In addition, if the pressing member includes an adjusting screw and a pressing member interposed between the valve element and the adjusting screw and movable only in the axial direction of the valve element, the influence of the rotation of the adjusting screw is reduced. It is possible to prevent the valve body from catching. Further, if the seal portion at one end side of the cylindrical valve body is formed separately from the valve body, the seal is easy, and the shape of the valve body is a simple shape that is straightforward to deform. Can be done.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the illustrated embodiment. In FIG. 1, reference numeral 1 denotes a cylindrical case having a bottom, and an adjusting screw 4 is screwed into an upper inner surface on an opening side. Screw 11 is formed on the bottom surface, a substantially cross-shaped through hole 12 is provided on the bottom surface, and the lower side surface is connected to the cuff to introduce the air in the cuff into the case 1.
3 are provided. Although the inner diameter of the case 1 in the illustrated example is different between the upper part and the lower part, they may have the same diameter, and the position of the inlet 13 is not limited to the illustrated position.

In the case 1, a pressing body 3 and a cylindrical valve body 2 are housed. The pressing body 3 in which the spring 6 disposed between the adjusting screw 4 and the spring contact surface 30 is in contact with the spring receiving surface 30 on one surface side has an annular groove 31 on the outer peripheral surface in which the O-ring 5 in contact with the inner surface of the case 1 is mounted. Further, a shaft portion 32 for holding the valve body 2 protrudes from the center of the other surface. The shaft portion 32 which has a cylindrical shape and a root portion having substantially the same diameter as the inner diameter of the cylindrical valve body 2 has a tip end side diameter smaller than the inner diameter of the valve body 2 and is formed in the through hole 12. Cross-shaped through hole 1 on the side of the tip to be inserted
2 and a pair of protrusions 3 for stopping rotation of the pressing body 3
3, 33 are formed. The portion of the through hole 12 where the protrusion 33 does not engage functions as the exhaust port 7.

The valve element 2 is a cylinder having both ends open as described above, and is formed of an elastic body such as rubber, and has a slit 21 long in the axial direction on the side wall. The longer and longer the number of the slits 21, the higher the pumping speed. The length and the number are set such that a predetermined pumping speed can be obtained in relation to the volume of the cuff to be connected. The cylindrical valve body 2 is disposed between the bottom surface of the case 1 and the pressing body 3, and is pressed between the pressing body 3 and the bottom surface of the case 1 by the pressure received from the adjusting screw 4 via the spring 6. Be pinched.

Although the valve body 2 is shown as a cylindrical one which is the most preferable shape, both the outer surface and the inner surface of the valve body 2 are defined only by the dimensional accuracy of a single mold at the time of formation. Any shape may be used as long as it is open at both ends, for example, a rectangular tube shape or a truncated cone shape having a tapered outer peripheral surface. However, in order to keep the correlation between the amount of compression of the valve body 2 and the amount of opening of the slit 21 linear, it is preferable that the change in thickness in the axial direction is small.

As described above, the valve body 2 to which the axially compressive force is applied by being pressed by the pressing screw 3 from the adjusting screw 4 via the spring 6 expands the central portion in the axial direction and the barrel type shown in FIG. Along with the slit 2
1 is opened. Since the opening amount corresponds to the applied compressive force, the opening amount can be adjusted to obtain a predetermined pumping speed. FIG. 3 shows the change in the PQ characteristic due to the adjustment in this configuration. It can be seen that the PQ characteristic can be linearly adjusted.

In this adjustment, since the adjusting screw 4 does not directly press the valve body 2 but interposes the spring 6, the adjusting screw 4 is selected by selecting the spring constant of the spring 6.
It is possible to set the amount of pushing of the valve body 2 for one rotation to a value not defined by the screw pitch.
In addition, the pressing body 3 interposed between the spring 6 and the valve body 2
Since only linear movement in the axial direction is permitted by the engagement of the through hole 12 of the case 1 and the valve element 2 receives only the compressive force in the axial direction, the adjusting screw 4
Although the adjustment is performed by rotating the valve body 2, the valve body 2 is not twisted.

Thus, the constant-speed exhaust valve has an inlet 13 which is connected to the cuff pressurized by the air pump.
At this time, pressure by high-pressure air is applied to the outer peripheral surface of the valve body 2, while the inner peripheral surface of the valve body 2 communicates with the atmosphere through the exhaust port 7. Therefore, the valve body 2 is elastically deformed in a direction to close the opening of the slit 21 due to the pressure difference between the two, and the exhaust port 7 is
Reduce the amount of air exhausted to When the pressure applied to the outer peripheral surface of the valve element 2 decreases, the valve element 2 increases the opening amount of the slit 21, so that the amount of passing air increases. Therefore, the PQ characteristics shown in FIG. 3 are obtained. The space above the space between the outer peripheral surface of the valve body 2 and the inner surface of the case 1 is closed by an O-ring 5 provided on the pressing body 3.
The lower part is closed by the end surface of the valve body 2 being in contact with the bottom surface of the case 1. The reason why the one end side is closed using the separate O-ring 5 is to simplify the shape of the valve body 2, and because the valve body 2 is in contact with the inner wall of the case 1, the influence of the uneven shape of the inner wall is obtained. In order not to be affected.

FIG. 2 shows an embodiment in which the bottom of the case 1 is completely closed and the exhaust port 7 is formed in the pressing body 3 and the adjusting screw 4. Pressing body 3 into case 1
Is the same as the above embodiment in that only the straight traveling is possible by the engagement with the above, but the spring 6 is eliminated and the adjustment screw 4 is brought into direct contact.

[0021]

As described above, according to the present invention, since the valve element is formed in a cylindrical shape having both ends opened, both the inner surface and the outer surface can be determined by only one mold at the time of molding. Therefore, it is easy to obtain a material that hardly causes uneven thickness, that is, a material having a constant exhaust speed with a reduced exhaust speed due to uneven thickness, thereby improving the production yield. be able to.

If the pressing member includes an adjusting screw and a spring interposed between the valve body and the adjusting screw,
By selecting the spring constant, the compression force applied to the valve body can be moved away from a state in which the compression force is uniquely determined by the screw pitch, so that the operation of adjusting the exhaust speed becomes easy. Also,
If the pressing member includes an adjusting screw and a pressing member that is interposed between the valve element and the adjusting screw and that is movable only in the axial direction of the valve element, the influence of the rotation of the adjusting screw may affect the valve element. To prevent the valve body from being twisted, the change in the amount of opening of the slit with respect to the axial compression force applied to the valve body can be kept linear, and good exhaust characteristics and good adjustability And has

Further, if the seal portion at one end side of the cylindrical valve body is formed separately from the valve body, the sealing becomes easy, and the shape of the valve body is changed so that its deformation is straightforward. And the valve body is not affected by the irregular shape of the inner wall of the case, so that the change in the amount of opening of the slit with respect to the axial compressive force applied to the valve body can also be kept linear. As a result, the exhaust characteristics and the adjustability can be improved.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of one embodiment, and FIG. 1B is a bottom view of the same.

FIG. 2 is a sectional view of another example.

FIG. 3 is a pressure-displacement (PQ) characteristic diagram according to the first embodiment;

FIG. 4 is a sectional view of a conventional example.

FIG. 5 is a sectional view of another conventional example.

FIG. 6 is a characteristic diagram showing theoretical values and actual values of PQ characteristics.

FIG. 7 is a characteristic diagram showing an influence of uneven thickness of PQ characteristics.

[Explanation of symbols]

 2 Valve body 3 Pressing body 4 Adjusting screw 6 Spring 21 Slit

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Makoto Fujiwara 1048 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 5/00-5 / 03

Claims (4)

(57) [Claims] 1. A valve body formed of an elastic body and having a slit for changing an opening amount according to a fluid pressure applied to an outer surface, and a pressing member for pressing the valve body to adjust the opening amount of the slit. A constant-speed exhaust valve, wherein the valve body is provided with a compressive force in the axial direction by a pressing member and has a slit in a side wall, and has a tubular shape with both ends opened. . 2. The constant-speed exhaust valve according to claim 1, wherein the pressing member comprises an adjusting screw and a spring interposed between the valve body and the adjusting screw. 3. The pressure member according to claim 1, wherein the pressing member comprises an adjusting screw, and a pressing member interposed between the valve body and the adjusting screw and movable only in the axial direction of the valve body. Constant speed exhaust valve. 4. The constant-speed exhaust valve according to claim 1, wherein the seal portion at one end of the valve body is formed separately from the valve body.