JPH01115343A - Vital capacity meter with double rolling seal - Google Patents

Abstract

PURPOSE: To enable a smooth rotation of a piston for a spirometer by arranging two rolling membranes so effectively that one membrane acts as buffer to protect the other membrane. CONSTITUTION: A spirometer 20 has a housing 21 bordered by a chamber 22 and a cylindrical casing 23 is mounted. A cup-shaped piston 34 is arranged inside a cylindrical chamber 35 of the external casing 23 and a piston 34 has a cylindrical side wall 36 and a conical recessed end wall 37. A membrane 50 has a circular folded part 50c thereof arranged inside confined to the axial direction of the piston 34 and a second membrane 51 is fastened on the casing 25 and the piston 34 in an opposite relation pertaining to the membrane 50. In the two membranes 50 and 51, the folded membranes 50c and 51c thereof are made to face each other in a mutual opposite relation thereby applying a stable, more smooth and more effective rolling action to the piston 34.

Description

[Detailed description of the invention] 1.

The present invention relates to a spirometer.

IL U1L U.S. Patent No. 3,722.506 discloses that the seal is
A spirometer is disclosed that is formed between a piston and an inner surface of a cylinder by a rolling seal membrane interposed between these two members. As an example of the prior art, a similar structure is shown here in FIG. A spirometer intended for measuring the respiratory volume or rate of breathing in humans comprises an outer casing 10 of cylindrical shape, which is used for the inlet (and outlet) of exhaled air. It has a tubular cavity 11 at one end. The air that has entered the cylindrical casing 10 passes through the piston 12
is moved to the forwardly extended position shown in the figure, and the extent of the movement is recorded by suitable recording means 13 connected to the piston shaft 14. 0-shaped seal M15
is arranged between the outer surface of the piston 12 and the inner surface of the cylindrical casing, one edge 15m of the membrane 15 being sealed against the piston 12, and one edge 15m of the membrane 15 being sealed against the piston 12;
5b is sealed against the casing 10.

FIG. 1 shows the piston at its maximum extension or
As shown near there, if the piston is
If not against the rear end wall 16 acting as a stop, then the piston 12 is moved along the inner wall of the casing 10 until the membrane 15 is extended along the inner wall of the casing 10, as shown phantom in FIG. Freely move forward an additional distance. In such a hypothetical situation, the stroke and volume of the spirometer would be increased, resulting in a larger capacity spirometer for a given diameter. However, in such a stretched spirometer, if the piston stroke is stretched as shown in FIG. , folded into the chamber as shown phantom in FIG. 1B. The possibility of such collapse is increased if the atmospheric pressure increases above the pressure in the room. In this way, if
If the internal pressure drops after the forced expulsion of the expelled air into the chamber, the atmospheric pressure on the opposite side of the membrane 15 will exert a force in the direction of the arrow 17 and the membrane 15 will collapse. death,
Alternatively, it may bulge into the chamber and interfere with the return movement of the piston 12 (FIG. 1B).

口(--yu) One feature of the present invention lies in the recognition and understanding of the above-mentioned problem and its functional reasons.

Another feature is that this problem is solved by the fact that two rolling membranes, one membrane acting as a buffer to protect the other against pressures that would otherwise promote membrane collapse. The object of the present invention lies in the discovery that this problem can be overcome by a less complex and highly effective arrangement.

The result is a spirometer with expanded stroke and volume for a given diameter, or conversely, a smaller diameter that has less inertia and greater sensitivity for a given volume. It is a unit of

A counter-folding elastic membrane is affixed at each of its edges to the outer surface of the piston and the inner surface of the cylinder, so that the rolled folds of the membrane face each other. A confined space is provided between the outer surfaces of the folds, also to ensure against the possibility of collapse of the belly and to improve the rolling of the membrane as the piston extends and retracts. , means are provided for reducing the pressure within the space. Applying a reduced pressure inside the space between the membranes tends to cause a slight stretching of the membrane in the region of the folds and an increase in the rounding of the curvature, resulting in a greater linearity of response. becomes. In other words, the initial resistance to piston movement that might otherwise be caused by the sharpness or steepness of the folds and the force required to change their profile is reduced. This is because the low pressure in the space between the membranes causes a slight stretching and widening of the folds, giving them a smoother and more evenly rounded profile, which makes the sealing member or This is because a more effective low resistance rolling action of the membrane is produced.

The dual rolling seal of the present invention not only allows greater piston stroke and spirometer capacity for a given piston stroke, but also provides a smoother, more uniform rolling seal action. , which enhances the linearity of response and increases automatic alignment of the piston. Return of the piston to its starting or "zero" position is effectively accomplished by a tortuous leaf spring connected to the piston and the spirometer housing. Appearance is U.S. Patent No. 3,
Although similar to the leaf springs disclosed in No. 086,515, the springs are mounted and arranged to perform different functions and achieve different results. especially,
The tortuous spring used here is such that its piston return force is at its maximum when the piston is fully retracted (i.e., its zero position) and decreases progressively as the piston extends. It is located in When the piston reaches the forward limit of its stroke, the spring is closed to a neutral condition and a return force is exerted by the spring at its maximum on the spirometer system.

1'21 Other features, objects, and advantages of the invention will become apparent from the following description and the accompanying drawings.

Referring to Figures 2-5 of the drawings, reference numeral 20 generally designates a spirometer having a housing 21 bounding a chamber 22, within which are the following: A generally cylindrical casing 23 is attached. The cylindrical casing 23 is supported by its horizontally extending shaft. One end of the cylindrical casing 23 is open, and the opposite end is closed by an end wall 24. In the illustrated embodiment in which a breathing tube 26 extends through both this end wall 24 and the spirometer housing 21, a cylindrical side wall 25 is formed in two parts, a front portion 25m and a rear portion 25b. However, this two-part construction is primarily advantageous in ease of manufacture and maintenance and, if desired,
It should be understood that the outer casing 23 can also be formed as a single unitary structure.

The outer casing 23 is partially supported inside the chamber 22 by an annular collar 27, which
Fitting tightly into the open end of the casing 23, the collar 27 is adapted to be secured to the wall of the housing 21 by screws 28 or any other suitable means. . Furthermore, in the illustrated configuration, the casing 23 is supported within the chamber 22 by a horizontal guide rod 29, which extends axially through the casing 23, and Its threaded end 29a passes through the end wall 24 at a central point and the drilled mount of the housing 21 projects through the bracket. A nut 31 securely fixes one end of the guide rod in place. Second
As shown in FIGS. 3 and 3, the guide rod 29 has its front end portion supported by a platform 33 of the housing 21 and projects through the bracket 32 .

-a cup-shaped piston 34 is mounted on the outer casing 2;
The piston 34 has a cylindrical side wall 36 and a conical concave end wall 37. Front part 38a and rear part 3
An elongate hub 38 consisting of 8b is secured to the end wall 37. A hole 39 extends through the hub 38 and the portion of the end wall 37 that is sealed between the two parts 38a, 38b of the hub 38 and slidably receives the horizontal guide bar 29.

The piston 34 is provided with a suitable recording means or indicator for recording the range of piston travel as exhaled air is forced into (and in some cases withdrawn from) the breathing tube 26. A horizontal arm 40, which is only represented in phantom in the case shown in FIG. The arm 40 is also coupled for back and forth movement as the arm extends and retracts. Arm 40 supports a pencil for recording the movement of the piston on a line sheet supported by a moving plate or rotating drum (not shown). Since such measuring or recording means are well known to those skilled in the art, and the details thereof do not form part of the present invention, further details are unnecessary. Believable. However, such measuring means can take the form of a potentiometer and, in its P4 case,
It is to be understood that all piston movements are represented and recorded by associated electronic means, including digital displays, which are well known to those skilled in the art.

The outer diameter of the cylindrical piston 34 is substantially smaller than the inner diameter of the casing 23 and the axial length of the piston is substantially smaller than the length of the chamber 35 bounded by the casing 23. Can be seen. In particular, the chamber 35 has a length approximately twice the length of the piston 34. - In detail, when the piston 34 is fully extended, as shown in FIG.
When chamber 4 is moved as far forward (to the left) as possible, chamber 3
5, the effective portion between the open end of the piston and the end wall 24 of the casing has an axial length that is substantially greater than the length of the piston, which is conventionally This is in contrast to the fact that in technology, effective lengths even equal to the length of a piston are extremely rare, if at all possible.

Within the annular region between the cylindrical casing side wall 25 and the concentric outer surface of the side wall 36 of the five-piston 34 are a pair of annular membranes 50 and 51, respectively, formed from an elastomeric material. Although each membrane can be considered to be generally cylindrical in shape when in its unfolded, untensioned state, U.S. Patent No. 3,722.506
The actual shape is slightly truncated conical, with outer end portions 50a and 51a having
The diameter is slightly smaller than that of the inner end portions 50b and 51b.
It can also be bigger.

The membrane 50 is arranged with its annular folded portion 50c within the axial limits of the piston 34 (regardless of the position of that piston) and with its annular outer end portion 50c.
0a is sealed and secured to the inner side wall of the casing 23, and its annular inner end portion 50b is sealed and secured to the piston 34 adjacent to its front end, on itself. 6 By forming the outer casing 23 into two parts which are folded in reverse, II! The ar* end of 150 can be tightly clamped between the sidewalls of the two sections, with the membrane 50 additionally acting as a sealing gas get between those sections. A suitable adhesive or sealant may be applied to the l&t&end portions 50 of the membrane 50.
b can also be used to secure it to the side wall 36 of the piston, but this is represented schematically by the slightly increased thickness of that part of the membrane 50. Alternatively, clamping means in the form of an external band of portion 50b for the purpose of maintaining an airtight seal between membrane 50 and piston 34! & can also be extended around the rear end portion 50b.

The axial length of the membrane 50 when the piston is fully retracted (FIG. 2) or fully extended (FIG. 5) is greater than the length of the piston 34 itself. It is only slightly smaller than Han. Further, the front end portion 50a of the J150 is attached to the end wall 24 of the casing 25.
from the piston 34 at a distance approximately equal to the axial length of the piston 34. In this manner, the distance traveled by piston 34 from its retracted position to its fully extended position substantially exceeds the axial length of piston 34.

The second B51 has a casing 25 and a piston 34,
They are secured in opposite relationship with respect to membrane 50. In particular, membrane 5
1 is also folded back onto itself and its annular outer end portion 51m is sealed and secured to the side wall 25 of the casing. 51 a rolls over the edge of the open end of casing 23 and is sealed and clamped between casing 23 and annular collar 27 . The annular inner end portion 51 b of the membrane 51 is attached to the piston 34 .
is sealed and secured adjacent the front end of the. In this case, too, a suitable adhesive or clamping means (in the form of a surrounding cord or band) is used to secure the extreme end of the reversed end portion 51b to the outer front end of the piston 34. It may also be provided to hold it in place relative to the section.

The two B50.51 are oriented with their folded parts 50c and 51c facing each other in a mutually opposed relationship. The position of each fold changes for a given membrane as the membrane 50.51 rolls during the extension and retraction of the piston 34, but the position of a rolled annular fold in one membrane changes over the other membrane. The relationship between the opposing folds remains constant regardless of the position of the piston 34.

The membranes 50,51 should be mounted such that their folds are axially spaced apart such that they bound an annular space 59 between them. and the membrane 50.51. Moreover, the spacing of the creases has a stabilizing effect on the piston 34, thereby causing the piston 3
4 and its guide rod 29 which increases friction.

The side wall 25 of the cylindrical casing 23 is one or
A gentle relative vacuum (1-101 in the water column) is provided within the space 59 between the membranes 50 and 51 with further openings provided.
It is connected to an exhaust line 60 leading to a suitable bong 761 or other vacuum source from which the vacuum can be deployed. Because of this relative vacuum, atmospheric pressure will cause the elastomer fi50.5
A force is applied to both walls of 1, keeping their membranes 5o, 51 fixed, but still able to move if necessary. Such a relative vacuum is
It has also been discovered that it reduces any adverse effects of the pressure difference between the ambient pressure and the pressure inside the front part of the chamber 35. The vacuum causes a slight stretching of the elastomeric membranes 50,51, causing their B50,51 to develop a smoother, layer-uniform roundness in the area of the folds. This helps eliminate any initial non-linearity whenever the piston 34 changes direction. Generally, a relatively positive external pressure causes the annular membrane seal to create a smoother seal around the periphery of the piston 34 as the piston 34 moves forward and rearward.
- The layer even provides an effective rolling action.

Membranes 50 and 51 can be formed from any durable, non-permeable, highly deformable elastomeric material. Silicone rubber has been found to be particularly effective, but other materials having similar properties may also be used.

A contoured, symmetrical leaf spring 70 is connected at its center to the piston 34 by a bracket 71 (FIG. 3) and at its ends to the housing 21.
are fixed to protrusions 72 at spaced intervals inside the chamber 22. The protrusion 72 is preferably aligned with the central axis of the piston 34 (
That is, it is equidistant from the guide rod 29) and the piston 3
It is desirable to be placed beyond the forward limit of movement of 4.

The central portion 70a of the spring 70 is curved steeply regardless of the position of the piston 34 (see Figure 2.4.5).
, however, the lateral arm portion 701] takes a different contour depending on the position of the piston 34. piston 34
is fully retracted, arm portion 70b projects laterally outwardly and generally in the same plane in the opposite direction (second .
Figure 3). As the piston 34 advances, the arm portion 70b
until, at the forward-most point of travel of the piston 34, the curved profile of each arm portion 70b appears as an inverse image and of approximately the same dimensions as the curved central portion 70a of the spring (FIG. 5). ), developing a forward directed curvature. In the state shown in FIG. 5, the spring 70 has almost returned to its neutral state.

If piston 34 is capable of appreciable additional forward movement without interference from projection 72 or other suitable stop means, the action of spring 70 is reversed and spring 70 will exert a forward pulling force on the piston 34. Since piston 34 is not capable of substantial forward movement, spring 70 always exerts a backward or return force on piston 34, but because
The force varies with the position of the piston 34, being at a minimum when the piston 34 is fully extended (FIG. 5) and at a maximum when the piston is fully retracted (FIG. 2). do. This result shows that the spring 70 is
during the latter part of the forward movement of the piston 34 when the rate of exhaled air flowing into the chamber 35 is relatively low. Second, it provides no appreciable resistance to forward movement of the piston 34. piston 3
The greater resistance exerted by the spring 70 at the beginning of the advance of 4 1 does not adversely affect the operation of the instrument. This is because at the beginning of the test, the force and flow rate of exhaled air entering the spirometer are at a minimum level.

In spirometer operation, for example, in a forced expiratory volume (FEV) test, the patient
4 is first placed in the retracted position shown in FIG. 2 and exhaled into a suitable mouthpiece (not shown) connected to breathing tube 26. Under those conditions, the main part of the axial length of the second Jg (51) extends rearwardly beyond the front of the piston 34 along the inner surface of the casing wall 25. When the piston 34 is moved by the entry of
Move to the middle region of the membrane 51 until a letter-shaped outline is taken (FIG. 4). Continued advancement of piston 34 then causes M 50 to unwind, exposing a portion of its length along wall 25 behind piston 34. In normal operation, piston 34 does not reach the forward-most limit of its stroke. Because this means that FEV
This is because it means that the volumetric capacity of the spirometer is exceeded. However, when for some reason the piston 34 is moved forward to its maximum extent,
It can be seen that the first membrane 50 extends rearwardly behind the piston 34 along the inner surface of the casing wall 25 for the main part of its axial length (FIG. 5).

Although the present invention has been described in detail for purposes of illustration, those skilled in the art will readily appreciate that many changes may be made to these details without departing from the spirit of the invention. This is where you can do it.

Since the present invention has the above-described structure and function, 21I! The novel spirometer has the effect of providing a novel spirometer in which the rolling membranes are arranged to act as a buffer to protect one of them from otherwise promoting the collapse of the other membrane. That is clear.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a spirometer having a conventionally known rolling seal; FIGS. 1^ and 18 are cross-sectional views showing hypothetical variations of the structure shown in FIG. 2 is a partial horizontal sectional view of an embodiment of the spirometer according to the invention, showing the piston in its retracted or zero position; FIG. 3 is a section taken along line 3--3 in FIG. A longitudinal section, FIG. 4, is similar to FIG. 2, while a partial horizontal section, FIG. 5, showing the piston in an intermediate position, is similar to FIG. FIG. 20... Spirometer, 21... Housing, 22...
- Chamber, 23... Cylindrical casing, 24... End wall, 25... Cylindrical side wall, 26... Breathing tube, 29.
... Guide rod, 34 ... Piston, 35 ... Cylindrical chamber, 36 ... Cylindrical side wall, 50.51 ... Membrane, 5
0a, 51m... annular external portion, 50b, 51b...
・Annular inner part, 50c, 51c...fold part, 7
0...Curved leaf spring, 70&...center portion, 70b...lateral arm portion, 72...protrusion.

Claims (1)

[Claims] 1. A spirometer for measuring the respiratory function of a human body, the spirometer comprising a rear wall and a side wall bounding a cylindrical chamber that is open at one end. a cylindrical casing having a cylindrical shape; a piston, port means in said rear wall for admitting exhaled air into said chamber behind said piston and discharging exhaled air from said chamber; said piston and an interior of said casing; sealing means disposed between the first and second annular membranes, each of which is in the form of a first and second annular membrane formed from an elastomeric material; an annular outer end portion folded back upon itself and sealingly affixed to the inner wall of the casing and an annular outer end portion sealingly affixed to the piston adjacent to the rear end of the piston; and said second membrane also has an annular outer end portion folded back upon itself and sealingly affixed to the inner wall of said casing. providing an annular inner end portion sealingly affixed to the piston adjacent the forward end of the piston; further, the first and second membranes have their respective folds directed toward each other; and the first membrane extends a major part of its axial length behind the front piston when the piston is at the front limit of its stroke. and the front second membrane extends its axial length forwardly beyond said piston when said piston is at the rear end of its stroke. A spirometer characterized by: 2. Each of the membranes is generally cylindrical in shape when in the unfolded state.
Spirometer described in section. 3. the folds of the first and second membranes are spaced apart;
2. The spirometer of claim 1, wherein the casing and piston together define an annular space of generally constant volume but which moves in position during spirometer operation. 4. The spirometer according to claim 3, further comprising means for maintaining the pressure in the space below atmospheric pressure. 5. The spirometer according to claim 4, wherein the negative pressure inside the space is maintained at 1 to 10 mm of water column. 6. The side wall of the casing is provided with an outlet port that communicates with the annular space, and means for maintaining the interior of the annular space below atmospheric pressure is connected to the outlet port. A spirometer according to claim 4, comprising a pump comprising: 7. said first membrane is oriented with a major part of one of its faces towards said side wall of said casing when said piston is at the rear limit of its stroke; 2. A spirometer as claimed in claim 1, wherein the spirometer is adapted to be directed inwardly away from said side wall when at the front end of the stroke. 8. said second membrane has a major portion of one of its surfaces directed outwardly towards the front side wall of the front casing when said piston is at the front limit of its stroke; The spirometer of claim 1, wherein the piston is directed inwardly away from the side wall when at the rear end of its stroke. 9. A spirometer for measuring the respiratory function of a human body, wherein the spirometer has a cylindrical shape having a rear wall and a side wall bounding a cylindrical chamber that is open at one end. a casing of the piston; a cylindrical piston supported for axial movement within the chamber and adapted to be connected to indicating means for instructing the axial movement; port means in said rear wall for admitting exhaled air into and discharging exhaled air from said chamber behind, said piston and said casing inner surface being disposed between said piston and said casing inner surface; sealing means, said sealing means being in the form of first and second annular membranes, respectively, formed from an elastomeric material, said first membrane being an annular outer end portion sealed and secured to the inner wall of the casing and an annular inner end portion sealed and secured to the piston adjacent to the rear end of the piston; and said second membrane also has an annular outer end portion folded back on itself and sealingly affixed to the inner wall of said casing and to the front end of said piston. the first and second membranes are arranged with their respective folds facing towards each other to provide an annular inner end portion that is adjacently and sealingly secured to the piston; and the first membrane extends a major portion of its axial length rearwardly beyond the front piston when the piston is at the front end of its stroke. further, the front second membrane extends its axial length forwardly beyond said piston when said piston is at the rear end of its stroke; The spirometer has spring means engaging said piston and exerting a force pushing said piston rearwardly within said chamber, the force exerted by the front spring means causing said piston to , a spirometer characterized in that it is larger when in its posterior limit than when in its anterior limit. 10. Housing means extends around and supports the casing, and the spring means includes a pair of arms extending outwardly away from each other and secured to the housing. 10. The spirometer of claim 9, comprising a tortuous leaf spring having a section and a curved central section connected to said piston. 11. The spirometer of claim 10, wherein the arm of the spring is secured to the housing at a spaced point before the front limit of stroke of the piston. 12. said arm portions extend laterally outwardly away from each other when said piston is retracted;
12. The spirometer according to claim 11, wherein the piston is curved forward when extended. 13. The spirometer of claim 9, wherein each of said membranes is generally cylindrical in shape when unfolded. 14. The folds of the first and second membranes together with the casing and piston bound an annular space of generally constant volume but varying position during extension and retraction of the piston. A spirometer according to claim 9. 15. The spirometer according to claim 14, further comprising means for maintaining the pressure in the space below atmospheric pressure. 16. The side wall of the casing is provided with an outlet port communicating with the annular space, and the means for maintaining the annular space below atmospheric pressure is connected to the outlet port. The spirometer according to claim 15, which is a vacuum pump. 17. The first film has a main part of one surface thereof,
When the piston is at the rear limit of its stroke, it faces outwardly towards the side wall of the casing, and when the piston is at the front limit of its stroke, the front 10. The spirometer according to claim 9, wherein the spirometer faces inward from the side wall. 18. The second film has a main part of one surface thereof,
oriented outwardly toward the side wall of the casing when the piston is at the front end of its stroke, and inwardly directed away from the side wall when the piston is at the rear end of its stroke. 10. The spirometer according to claim 9, which is adapted to be oriented in the opposite direction.