Peak flow meter-expiratory flow rate

Claim 2

Apparatus for measuring peak air flow comprising: housing means defining first and second cavities which communicate with one another, said first cavity having an input port and at least one output port and said second cavity having an output port; mobile piston means located in said second cavity and separating said first and second cavities, said piston means and the walls of the second cavity having a predetermined clearance therebetween, the output port of the second cavity being exclusively on one side of said piston means. spring means for restricting the motion of said piston means; indicating means for registering the peak excursion of said piston means, said indicating means including shaft means mobile with said piston means; and means for locking said shaft means in position of said peak excursion.

Claim 3

Apparatus as described in claim 1 wherein said housing means includes a plate pivotally mounted over the output ports of saiD first cavity, air flow from the output ports of said first cavity being limited by the position of said plate and the concommitant alteration of size of said output ports of said first cavity.

Claim 4

Apparatus as described in claim 1 wherein said second cavity is cylindrical in shape, with one end communicating with said first cavity and the other end conditioned to include said indicating means, said spring means being affixed between said housing means and said piston means.

Claim 5

Apparatus as described in claim 3 wherein said shaft means is connected to said piston means, and said means for locking includes a plug in said second cavity which defines a frustoconical cavity having sides sloping away from said piston means, and balls in said frustoconical cavity for limiting travel of said shaft toward said piston means by being lodged between said plug and said shaft means by downward force on said shaft.

Claim 6

Apparatus as described in claim 1 wherein said housing means forms a cylindrical body.

Claim 7

Apparatus as described in claim 1 wherein air flow scaling means demarcates said housing means in the range of mobility of said piston means.

Claim 8

Apparatus for measuring peak expiratory air flow from a user comprising: a first housing means defining a first cavity therein, one end of said means being adapted as a mouthpiece for receipt of expiratory air, and fitted with a screen to impede flow of particulate matter into said cavity, said means further defining a generally circular output port; a generally circular plate, larger in radius than said output port, affixed to said means above said output port, by means of a pivot screw located between the center and the periphery of said plate, whereby pivoting of said plate blocks a correspondingly variable extent of said output port; a generally cylindrical hollow member upstanding from said housing intermediate said mouthpiece and said output port, said member communicating directly at its lower end with said first cavity; a plug lodged in the top of said member defining an output port of predetermined size for said member said port including a frustoconical cavity as a portion thereof; an elongate piston slidably located in said member, said piston having a lower circular portion defining a predetermined clearance with the walls of said member and having an upper shaft portion penetrating the output port in said plug; a coil spring having one end affixed to said housing means and the opposite end affixed to said piston; a plurality of bearings located in said frustoconical cavity, thereby permitting upward movement of said shaft and restricting downward motion thereof; whereby calibrated flow of air from the output ports of said housing means and of said hollow member causes a displacement of said piston upwardly in said member in proportion to the peak expiratory air flow.

Claim 9

Apparatus for measuring peak expiratory air flow from a user comprising: a first housing means defining a first cavity therein, one end of said means being adapted as a mouthpiece for receipt of expiratory air, and fitted with a screen to impede flow of particulate matter into said cavity, said means further defining a generally circular output port; a generally circular plate, larger in radius than said output port, affixed to said means above said output port, by means of a pivot screw located between the center and the periphery of said plate, whereby pivoting of said plate blocks a correspondingly variable extent of said output port; a generally cylindrical hollow member upstanding from said housing intermediate said mouthpiece and said output port, said member communicating directly at its lower end with said first cavity; a plug lodged in the top of said member defining an output port of predetermined size for said member said port including a frustoconical cavity as a portion thereof; an elongate piston slidably located in said member, said piston having a lower circular portion defining a predetermined clearance with the walls of said member and having an upper shaft portion penetrating the output port in said plug; a coil spring having one end affixed to said housing means and the opposite end affixed to said piston; a plurality of bearings located in said frustoconical cavity, thereby permitting upward movement of said shaft and restricting downward motion thereof; whereby calibrated flow of air from the output ports of said housing means and of said hollow member causes a displacement of said piston upwardly in said member in proportion to the peak expiratory air flow.