Positive pressure exhale valve for a breathing apparatus

In some embodiments, a positive pressure exhale valve for a breathing apparatus that opens when internal pressure of a face piece of the breathing apparatus reaches a predetermined positive level includes a valve body, a first spring for always contacting the valve body so as to force the valve body in closing direction, and a braking body for opposing the valve body across a gap and contacting the valve body when a vibration body formed by the valve body and first spring experiences self-excited vibration, thereby suppressing the self-excited vibration.

This is a National Phase Application in the United States of International Patent Application No. PCT/JP2018/010096 filed Mar. 15, 2018, which claims priority on Japanese Patent Application No. 2017-081785, filed Apr. 18, 2017. The entire disclosures of the above patent applications are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a positive pressure exhale valve for a breathing apparatus that opens when internal pressure of a face piece of the breathing apparatus reaches predetermined positive level.

BACKGROUND ART

Patent Document No. 1 teaches a positive pressure exhale valve for a breathing apparatus that opens when internal pressure of a face piece of the breathing apparatus reaches predetermined positive level.

PRIOR ART DOCUMENT

Patent Document

DISCLOSURE OF INVENTION

Problem to be Solved

A positive pressure exhale valve comprises a valve body and a spring for always contacting the valve body so as to force the valve body in closing direction. A vibration body formed by the valve body and spring may cause a problem if it experiences self-excited vibration for some reason. Once self-excited vibration starts, its amplitude increases over time to the point of generating abnormal noise that gives displeasure to a user of the breathing apparatus.

Therefore, an object of the present invention is to provide a positive pressure exhale valve for a breathing apparatus that opens when internal pressure of a face piece of the breathing apparatus reaches predetermined positive level, which positive pressure exhale valve comprising a valve body and a spring for always contacting the valve body so as to force the valve body in closing direction, and which positive pressure exhale valve is prevented from experiencing self-excited vibration of a vibration body formed by the valve body and spring.

Means for Achieving the Object

In accordance with the present invention, there is provided a positive pressure exhale valve for a breathing apparatus that opens when internal pressure of a face piece of the breathing apparatus reaches predetermined positive level, which positive pressure exhale valve comprising a valve body, a first spring for always contacting the valve body so as to force the valve body in closing direction, and a braking body for opposing the valve body across a gap and contacting the valve body when a vibration body formed by the valve body and first spring experiences self-excited vibration, thereby suppressing the self-excited vibration.

The positive pressure exhale valve does not open unless internal pressure of the face piece of the breathing apparatus reaches predetermined positive value, because it is always forced in closing direction by the first spring. So as not to interfere with operation of the positive pressure exhale valve, the braking body opposing the valve body across a gap does not contact the valve body during normal operation of the breathing apparatus. A problem can arise in which some kind of disturbance acting on the breathing apparatus or the vibration body formed by the valve body and first spring causes the vibration body to experience self-excited vibration. Once self-excited vibration starts, amplitude of the vibration grows larger over time and causes the valve body to contact the braking body. When the valve body contacts the braking body, braking force acts on the vibration body and stops the self-excited vibration, thereby stopping abnormal noise generated by the self-excited vibration.

In accordance with a preferred aspect of the present invention, the braking body is a columnar resilient body.

Use of the columnar resilient body simplifies structure of the positive pressure exhale valve, thereby decreasing production cost of the positive pressure exhale valve.

In accordance with a preferred aspect of the present invention, the braking body is a second spring.

Displacement of the valve body is restricted by the columnar resilient body because the columnar resilient body usually has spring constant much larger than that of the first spring. As a result, a disadvantage may arise wherein the valve body comes into contact with the braking body to be restricted in displacement to the point that divergence of the valve body appropriate for user breathing cannot be obtained when breathing of the user of the breathing apparatus is hard beyond normal level. The braking body made of a second spring provided with appropriate spring constant allows the valve body to displace farther after contacting the braking body, i.e., the second spring. As a result, self-excited vibration of the vibration body formed by the valve body and first spring can be suppressed and divergence of the valve body appropriate for user breathing can be obtained when breathing of the user of the breathing apparatus is hard beyond normal level.

In accordance with a preferred aspect of the present invention, spring constant of the second spring is set at a value larger than that of the first spring.

When spring constant of the second spring is set at a value larger than that of the first spring, braking force applied from the second spring to the vibration body formed by the valve body and first spring becomes large and the self-excited vibration of the vibration body can be effectively stopped.

In accordance with a preferred aspect of the present invention, the second spring is a coil spring whose one end distant from the valve body engages a hook formed on a support member and whose tip portion of said one end is bent and passed through a hole formed in the support member.

A coil spring is easily available and therefore a good choice for the second spring. When a coil spring is used for the second spring, it is necessary to engage one end of the coil spring distant from the valve body with a support member. It is effective to engage the coil spring with a hook formed on the support member at one end distant from the valve body. Said one end of the coil spring that engages the hook on the support member must be a flat portion. If a slanted portion of said one end of the coil spring should engage the hook on the support member, the coil spring would slant as a whole and cause one side of the coil spring to contact the valve body and thereby impair the coil spring's function of suppressing self-excited vibration. When a tip portion of said one end of the coil spring is bent and passed through a hole formed in the support member, relative circumferential position between the coil spring and the support member is fixed and the flat portion of said one end of the coil spring can surely engage the hook on the support member.

MODES FOR CARRYING OUT THE INVENTION

A positive pressure exhale valve for a breathing apparatus in accordance with a preferred embodiment of the present invention will be described.

As shown inFIGS.1to3, a breathing apparatus A is provided with a face piece B. The face piece B is provided with a circular opening B1at one side portion. An annular shaped exhale valve receiving member C is passed through the opening B1from the inside of the face piece B and fixed to the face piece B.

A positive pressure exhale valve1covers the opening B1from the outside of the face piece B and is snap fitted on and fixed to the exhale valve receiving member C through an annular shaped seal member D.

The positive pressure exhale valve1is provided with an exhale valve seat2. The exhale valve seat2is provided with an annular shaped valve seat forming member2aand plurality of hooks2bfor snap fitting the valve seat forming member2aon the exhale valve receiving member C. The hooks2bare disposed circumferentially distanced from each other and formed on the valve seat forming member2a. The positive pressure exhale valve1is further provided with a tubular bearing2clocated at the center of a circle formed by the valve seat forming member2aand through which a valve shaft of a valve body that will be described later is inserted, a plurality of arm members2dfor connecting the tubular bearing2cto the valve seat forming member2a, a pair of hooks2eof a female part of a bayonet connection mechanism, and a pair of recesses2fof a female part of a lock mechanism.

The positive pressure exhale valve1is provided with a valve body3. The valve body3is provided with a circular disk shaped flexible main valve body3amade of silicon rubber, a valve shaft3bmade of hard plastic material and disposed coaxially with the main valve body3a, and an annular shaped spring holder3cmade of hard plastic material and disposed coaxially with the main valve body3a. The spring holder3cis provided with an annular shaped plate portion3c1and a cylindrical portion3c2disposed at an inner peripheral portion of the annular shaped plate portion3c1. The main valve body3a, the valve shaft3band the spring holder3care insert molded integrally with each other.

The positive pressure exhale valve1is provided with a first coil spring4. Opposite ends of the first coil spring4form a pair of flat planes extending at right angles to the longitudinal axis of the coil spring4and extending parallel with each other. The coil spring4fits on the cylindrical portion3c2of the spring holder3cand abuts the annular plate portion3c1at one end.

The positive pressure exhale valve1is provided with a second coil spring5disposed coaxially with the first coil spring4. The second coil spring5is formed smaller in diameter and shorter in length than the first coil spring4. The second coil spring5is disposed inside of the first coil spring4. Spring constant of the second coil spring5is set at larger than that of the first coil spring4. The second coil spring5operates as a braking member for a vibration body formed by the valve body3and first coil spring4. Opposite ends of the second coil spring5form a pair of flat planes extending at right angles to the longitudinal axis of the second coil spring5and extending parallel with each other. The second coil spring5opposes a portion of the main valve body3aextending inside of the cylindrical portion3c2of the spring holder3cacross a predetermined gap at one end. Tip portion of the other end of the second coil spring5is bent in the extending direction of longitudinal axis of the second coil spring5.

The positive pressure exhale valve1is provided with a spring retainer G. The spring retainer6is provided with a conical circumferential side wall6a, a top wall6band a pair of hooks6cof a male part of a bayonet connection mechanism. The hooks6care formed by tip portions of a pair of leg portions extending from the circumferential side wall6a. The spring retainer6is further provided with a pair of hooks6dof a male part of a lock mechanism. The hooks6dare formed by tip portions of another pair of leg portions extending from the circumferential side wall6a. The spring retainer6is further provided with a cylindrical portion6eformed on back side of the top wall6b, three second spring engaging hooks6fdisposed circumferentially distanced from each other and formed on back side of the top wall6b, and a small diameter through hole6gformed in the top wall6bfor use in positioning the second coil spring5.

The hooks2eof the female part and the hooks6cof the male part can be detachably engaged with each other and form a bayonet connection mechanism for connecting a pair of members by pushing and twisting operation. The spring retainer6and the exhale valve seat2are detachably connected by the aforesaid bayonet connection mechanism. The hooks6dof the male part and the recesses2fof the female part can be detachably engaged with each other and form a lock mechanism. Connection between the spring retainer6and the exhale valve seat2is stably maintained by the aforesaid lock mechanism.

The other end of the first coil spring4fits on the cylindrical portion6eon the back side of the top wall6bof the spring retainer6and abuts the back side of the top wall6b. The first coil spring4clamped at opposite ends by the valve body3and the spring retainer6forces the valve body3in closing direction so as to abut the main valve body3aon the valve seat forming member2a.

The second coil spring5is retained by the spring retainer6with the other end forming a flat plane engaged with the three hooks6fon the back side of the top wall6band tip portion5aof the other end passed through the small through hole6gof the top wall6b. As aforementioned, said one end of the second coil spring5opposes the portion of the main valve body3aextending inside of the cylindrical portion3c2of the spring holder3cacross a predetermined gap. Said gap is determined based on measurements of displacement of the valve body3carried out on an actual positive pressure exhale valve1when the exhale valve1operates normally and when the exhale valve1experiences self-excited vibration.

The positive pressure exhale valve1is provided with a cover member7. The cover member7is provided with a conical circumferential side wall7aand a top plate7bfixed to the circumferential side wall7athrough a plurality of arm members. An annular opening7cis formed between the top plate7band the circumferential side wall7a. The annular opening7cis divided into a plurality of intermittent arc openings by said plurality of arm members.

The cover member7is connected to the exhale valve seat2to be capable of opening and closing through a hinge mechanism8.

Closed condition of the cover member7is maintained to be releasable through a snap-fitting mechanism9.

Operation of the positive pressure exhale valve1will be described.

The breathing apparatus A is provided with a motor fan. In the breathing apparatus A, internal pressure of the face piece B is always maintained positive and external air is supplied to the face piece B through the motor fan only when a user of the breathing apparatus inhales.

When the internal pressure of the face piece B reaches a predetermined level during exhale of the user, the valve body3moves in opening direction against biasing force of the first coil spring4so as to open the positive pressure exhale valve1. As a result, exhaled air in the face piece B is discharged to the external environment.

When the breathing apparatus A is used normally and breathing of the user is not abnormally hard, the valve body3does not contact the second coil spring5during exhale, so that the valve body3opens and closes under the biasing forces from the first coil spring4and the internal pressure of the face piece B.

A problem can happen in which some kind of external disturbance acts on the breathing apparatus A or a vibration body formed by the valve body3and first coil spring4so that the vibration body experiences self-excited vibration. Once the self-excited vibration starts, its amplitude grows larger over time to the point of generating abnormal noise that gives displeasure to a user of the breathing apparatus A. However, in the breathing apparatus A, when the amplitude of the self-excited vibration of the vibration body formed by the valve body3and first coil spring4becomes large, the valve body3contacts the second coil spring5, i.e., a braking body. When the valve body3contacts the second coil spring5, braking force acts on the vibration body3from the second coil spring5so as to stop the self-excited vibration, thereby stopping abnormal noise generated by the self-excited vibration. As can be seen from the above explanation, self-excited vibration of the vibration body formed by the valve body3and first coil spring4is effectively suppressed in the positive pressure exhale valve1.

The second coil spring5has an advantage in that since it does not contact the valve body3during normal operation of the positive pressure exhale valve1, it does not interfere with normal operation of the positive pressure exhale valve1and therefore does not obstruct normal operation of the positive pressure exhale valve1.

Spring constant of the second coil spring5is set at a value larger than that of the first coil spring4so that large braking force is applied from the second coil spring5to the vibration body formed by the valve body3and first coil spring4. Thus, the self-excited vibration of the vibration body can be effectively stopped.

Spring constant of the second coil spring5is desirably set at an appropriate value that enables the valve body3to continue to displace in opening direction after it contacts the second coil spring5. This makes it possible not only to suppress the self-excited vibration of the vibration body formed by the valve body3and first coil spring4but also to increase divergence of the positive pressure exhale valve1to a level appropriate for user breathing when the breathing of the user of the breathing apparatus A is extremely hard.

As the second coil spring5is easily available, it is suitable for use as a braking member for the vibration body formed by the valve body3and first coil spring4. When the second coil spring5is used as a braking member, it is necessary to retain the second coil spring5by the spring retainer6at said another end distant from the valve body3. An effective retaining method is to engage the second coil spring5with the hooks6fformed on the spring retainer6at said another end distant from the valve body3. A flat portion of said another end of the second coil spring5must engage the hooks6fof the spring retainer G. If a slanted portion of said another end of the second coil spring5should engage the hooks6fof the spring retainer6, the second coil spring5would slant as a whole and cause one side of the second coil spring5to contact the valve body3and thereby impair the coil spring's function of suppressing self-excited vibration. When a tip portion of said another end of the second coil spring5is bent and passed through the hole6gformed in the spring retainer6, relative circumferential position between the second coil spring5and the spring retainer6is fixed and the flat portion of said another end of the second coil spring5can surely engage the hooks6fof the spring retainer G.

Instead of the second coil spring5, a hard or soft columnar resilient body can be used as the braking member for the vibration body formed by the valve body3and first coil spring4. The columnar resilient body simplifies structure of the positive pressure exhale valve1, thereby decreasing production cost of the positive pressure exhale valve1. However, once the valve body3contacts the columnar resilient body, displacement of the valve body3is restricted by the columnar resilient body because the columnar resilient body usually has spring constant much larger than that of the first coil spring4. As a result, a disadvantage may arise wherein the valve body3comes into contact with the columnar resilient body to be restricted in displacement to the point that divergence of the valve body3appropriate for user breathing cannot be obtained when breathing of the user of the breathing apparatus1is hard beyond normal level.

INDUSTRIAL APPLICABILITY

The present invention can be widely used for positive pressure exhale valves for breathing apparatuses

BRIEF DESCRIPTION OF THE REFERENCE NUMERALS