JPS6345048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure sensor for detecting gas or fluid pressure as a mechanical displacement amount.

Conventionally, pressure sensors that detect gas or fluid pressure and convert it into mechanical displacement have been known to be made of metal or rubber, such as diaphragms or bellows. In some cases, a large amount of energy is required to displace the material itself, and in order to obtain the amount of mechanical displacement, the conversion efficiency must be extremely low. The drawback was that it was difficult to obtain sufficient performance over a long period of time due to changes. Another problem is that these pressure sensors are extremely inconvenient especially when precision is required, such as when used in blood pressure monitors.

The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a pressure sensor that can extract the amount of pressure change extremely efficiently and accurately as a large amount of mechanical displacement.

Hereinafter, the present invention will be explained in detail according to the illustrated embodiments. FIG. 1 is a front view showing a cross section of the upper half of the pressure sensor according to the present invention, where 1 is a main body case, and one end has a pressure receiving port 1a through which pressure is sent through a rubber or the like (not shown), and other parts. Flange portions 1b each having threaded portions 1bb formed at three locations are provided at each end, and a hollow portion 1c is formed. Reference numeral 2 denotes a guide case, which has a guide hole 2a penetrating through the center, protrusions 2b and 2c protruding from both sides in a concentric disk shape with respect to the guide hole 2a, and a stepped portion 2 similarly formed in a concentric circle.
d. Holes 2e are provided at positions corresponding to the threaded portions 1bb formed in the flange portion 1b of the main body case 1, respectively. 3 is a screw,
At the threaded part 1bb and hole 2e, the main body case 1
and guide case 2 are integrally fixed to form a cylinder part. Reference numeral 4 denotes a displacement member, whose center portion is supported movably in the axial direction by a guide hole 2a of the guide case 2, and a hollow portion 1c within the main body case 1.
A head 4a is fixed to one end projecting outward, and a male threaded portion 4b is formed at the other end projecting to the outside. 5 is a bag-shaped member made of rubber, for example;
Although it is formed thin, the flange 5a of the opening is formed thick, and the flange 5a is fixed within the step 2d of the guide case 2 by the main case 1 and the guide case 2. It is fixed and held by the presser ring 6, and the inner bottom part is in contact with the head 4a of the displacement member 4. A coil spring 7 is interposed between the guide case 2 and the head 4a of the displacement member 4, and springs to move the head 4a toward the pressure receiving port 1a. Further, the outer circumferential surface of the spring 7 is formed to slightly touch the inner surface of the bag-shaped member 5. 8 is an adjustment nut, which is connected to the threaded portion 4b of the displacement member 4.
is engaged in. Reference numeral 9 denotes a coil spring, which is interposed between the guide case 2 and the adjustment nut 8 and springs so as to push out the male threaded portion 4b, that is, to pull the head 4a back into the main body case 1.

Next, the operation of the sensor configured as described above will be explained.

First, the adjusting nut 8 is rotated appropriately in advance to move the displacement member 4 into and out of the guide case 2, so that the adjusting nut 8 is fixed in a state in which its head 4a is in contact with the bottom of the bag-like member 5. At this time, the bag-shaped member 5 is in the illustrated state in which the brim 5a is fixed to the guide case 2, and is in light contact with the head 4a of the displacement member 4 and the outer peripheral surface of the coil spring 7, and no external force is applied to it. It is kept in a state where it is not. This adjustment can be performed delicately because the elastic forces of the coil springs 7 and 9 oppose each other in the axial direction of the displacement member, and it also responds delicately to pressure changes within the main body case, which will be described later.

Here, if air is sent from an air balloon to the pressure receiving port 1a of the main body case 1, for example, via a rubber tube (not shown) and a cuff serving as a blood pressure measuring device,
The air pressure inside the device is increased and pressure is applied to the arm cuff, and the airtight hollow part 1 of the main body case 1
The pressure of c is also increased. When the pressure in the hollow portion 1c is increased, pressure is uniformly applied to the entire surface of the bag-shaped member 5, and as a result, a coil spring 7 is attached to the head 4a of the displacement member 4 as shown in FIG. A force A is applied in a direction (to the right in FIG. 1) that compresses the displacement member 4 and pushes the displacement member 4 to the outside, and a force B directed inward of the coil spring 7 is applied to the bag-shaped member 5 on the outer periphery of the coil spring 7. will be added evenly. By this, if the bag-like member 5 is made of a rubber body having an appropriate thickness and hardness in advance, the bag-like member 5 can be inserted inwardly in the gap between the coil springs 7 as shown in FIG. Since the displacement member 4 is easily and uniformly deformed into a bellows-like shape as it approaches, the displacement member 4 is almost unaffected by the deformation action of the bag-like member 5, and the springs of the coil springs 7 and 9 whose elastic directions are opposite to each other. According to the constant, it is sensitively displaced to the right in FIG. 1 in response to the sending force to the pressure receiving port 1a. The amount of displacement of the displacement member 4 may be directly read by interlocking a pointer or the like (not shown), or by moving a slit plate through a gear mechanism to photoelectrically generate electric pulses. The number may be counted and displayed digitally, or the amount of light received may be changed photoelectrically by interlocking with an aperture device, and the display device may be operated with an amount of electricity corresponding to the amount of light received, allowing for reading. do it.

Note that the coil spring 7 has a spring constant larger than that of the coil spring 9, and the winding interval is set appropriately. As a result, the elastic force of the coil spring 9 having a small spring constant can be appropriately adjusted using the adjustment nut 8, and the sensitivity of the displacement member can be delicately and freely adjusted.

The bag-shaped member 5 may be made of only a rubber body as described above, or it may be made of a flexible material such as a fiber coated with rubber on both sides, such as plastic, which has high tensile strength and good flexibility. It can also be used. In addition, main body case 1 and guide case 2
If necessary, a rubber packing may be used for the joint surface with the guide case 2, and an oilless metal, a bearing, etc. may be used for the guide hole 2a of the guide case 2.

In the embodiments detailed above, the case where the pressure sensor of the present invention is applied to a blood pressure measuring device is explained as an example, but it is needless to say that the pressure sensor to be measured is not limited to this, and the pressure medium to be measured is a gas. The present invention is not limited to the above-described embodiments, such as that fluid may be used instead.

As described above, according to the pressure sensor of the present invention,
The two elastic bodies with opposing springing directions respond sensitively to changes in pressure, allowing the deformation process of the bag-like member to occur naturally and extremely smoothly as pressure is sent to the sensor, and the gap between the spring and Even in this case, only the constant of the spring acts when the pressure of the displacement member moves without causing any shearing phenomenon accompanied by friction and without being affected by aging of the bag-like member, making it sensitive to changes in the pressure to be measured. Coupled with the ability to obtain a large displacement output, highly accurate pressure measurement can be easily performed using an extremely simple mechanism.

Furthermore, in the pressure sensor of the present invention, the response to pressure can be adjusted by using a spring adjustment means, so a wide measurement pressure range can be set, and the device can therefore be made more versatile.

[Brief explanation of drawings]

FIG. 1 is a front view showing a cross section of the upper half of the pressure sensor according to the present invention, and FIG. 2 is an explanatory diagram of the operation of the main part of FIG. 1. 1... Main body case, 1a... Pressure receiving port, 1c...
Hollow part, 2... Guide case, 2a... Guide hole, 4... Displacement member, 4a... Head, 4b... Threaded part, 5... Bag-shaped member, 7, 9... Coil spring,
8... Adjustment nut.

Claims (1)

[Scope of Claims] 1. A displacement member is disposed so as to be movable in and out of a main body case having at least one pressure receiving port, and a first
By arranging the spring and covering the displacement member of the spring arrangement part with a bag-like member made of a flexible material, the hollow part of the main body case and the displacement member side are airtightly partitioned. A separate second spring is provided for a portion of the displaceable member located outside the main body case, which functions as an aggregate of the bag-like member, and a second spring is connected to the first spring inside the main body case and its elastic force. are arranged so that they face each other, and a means for adjusting the elastic force is arranged with respect to the second spring,
A pressure sensor characterized in that a change in pressure transmitted through a pressure receiving port is detected as an amount of displacement of a displacement member. 2. The pressure sensor according to claim 1, wherein the bag-like member is made of a rubber body. 3. The pressure sensor according to claim 1, wherein the amount of displacement of the displacement member is displayed as the amount of variation of the pointer via a mechanical interlocking mechanism.