Foot-operated speed control for air-driven tool

Claim 2

A foot control for controlling the speed of an air-driven motor, said control comprising: a control block, means defining a cavity extending into said block from an upper surface opening thereof, said cavity including an upper piston chamber, a lower inlet air chamber and a narrow neck passage means interconnecting said chambers; means defining an inlet air passage extending through said block into said inlet air chamber from an inlet air port at a surface portion of said block; means defining an outlet air passage extending from a portion of said cavity above said inlet chamber through said block to an outlet air port at a surface portion of said block; and means defining a one-piece combination piston-poppet means movable within said cavity, including a piston portion movable within said piston chamber in sealed engagement with the walls of said chamber and a narrower stem portion extending downwardly from said piston portion into said neck passage and having a maximum diameter less than the diameter of said piston portion; said stem portion including sealing means operable to close said neck passage means when said piston is in an upper position within said piston chamber; said stem portion including said sealing means being movable downwardly into said inlet air chamber solely under foot pressure to open said neck passage means upon downward movement of said piston under foot pressure from said upper position and being movable upwardly solely under air pressure acting in opposition to said foot pressure to close said neck passage.

Claim 3

A control according to claim 1 including a foot pressure operated piston actuator means separate from and movable relative to said piston portion and having a contact portion adapted to engage directly an upper surface of said piston portion upon application of foot pressure to said actuator means.

Claim 4

Apparatus according to claim 2 wherein said piston portion has a convexly curved upper surface engageable by said contact portion to enable downward movement of said piston through application of foot pressure to any surface area on an upper surface of said actuator means.

Claim 5

Apparatus according to claim 3 wherein said actuator means comprises a depressible actuator button and said contact portion projects downwardly toward said piston from a central undersurface portion of said button, said button being mounted for limited universal movement in alignment with said piston portion, whereby foot pressure applied to any upper surface portion of said button causes said contact portion to engage and depress said piston portion.

Claim 6

A control according to claim 1 wherein said stem portion includes a tapered portion tapering outwardly in a downward direction along said stem portion from said piston portion to said sealing means, said tapered stem portion providing a gradually variable orifice at the opening of said neck passage means into said inlet air chamber upon downward movement of said piston within said piston chamber.

Claim 7

A control according to claim 5 wherein said stem portion tapers gradually outwardly in a downward direction from said piston portion and terminates at a lower sealing end portion of smaller diameter than said neck passage means and carrying said sealing means for sealed engagement with the interior wall of said neck passage means.

Claim 8

Apparatus according to claim 1 wherein said cavity extends vertically through said block from said upper surface opening to a bottom surface opening thereof, a base plate mounting said block and means sealing said bottom surface opening against said base plate, a housing enclosing the sides of said block and fixed to said base plate, a single large depressible foot button separate from and of substantially larger diameter than said piston portion centered within and closing an upper opening of said housinG and including contact means extending downwardly from a central lower surface portion of said button for engaging an upper surface of said piston portion and moving said piston portion downwardly upon application of a downward foot pressure to said button.

Claim 9

A control according to claim 1 wherein said piston and stem are relatively sized and shaped such that air back pressure within said piston chamber exerts a differential pressure acting upwardly against bottom surface portions of said piston sufficient to move said piston-poppet means upwardly to close said neck passage means in the absence of foot-applied downward force acting against the upper surface of said piston portion.

Claim 10

A control according to claim 1 including piston-poppet moving means operable to move said piston-poppet means downwardly and upwardly within said cavity to open and close said neck passage, said moving means comprising solely a rigid depressible footoperated actuator means in direct engagement with an upper surface portion of said piston portion for effecting downward movement of said piston-poppet means upon application of foot pressure to said actuator means, and air pressure acting upwardly against bottom surface portions of said piston-poppet means for effecting upward movement of said piston-poppet means.

Claim 11

A control according to claim 2 wherein the foot pressure applied to said actuator means required to effect downward movement of said piston-poppet means within said cavity varies directly with and is solely a function of the air pressure in said piston chamber.

Claim 12

A manually operated fluid valve comprising: a valve block including a valve cavity extending inwardly of said block from a surface opening therein, a movable valve member movable axially within said cavity solely by manual pressure in a valve-opening direction and solely by fluid pressure in the opposite valve-closing direction, whereby said valve is characterized by the absence of springs for effecting movement of said valve member, said movable valve member including a valve piston movable axially within a first cavity section and including piston sealing means in fluid sealing engagement with the walls of said first cavity section to prevent escape of fluid from said surface opening, said movable valve member including a valve stem extending axially from a bottom surface portion of said piston within a second cavity section and including stem sealing means in fluid sealing engagement with the walls of said second cavity section and spaced axially from said piston sealing means, said stem sealing means being movable out of fluid sealing engagement upon movement of said piston under manual pressure in a valve-opening direction, a fluid inlet port in said block opening into said cavity upstream of said stem sealing means when said stem is in sealing engagement with said second cavity section, a fluid outlet port in said block opening into said cavity between said piston sealing means and said stem sealing means, whereby movement of said piston under manual pressure in a valve opening direction enables fluid flow from said inlet port into said valve cavity and past said stem sealing means into said outlet port, said stem and piston being sized such that fluid back pressure from said outlet port acting between said piston sealing means and said stem sealing means creates a variable differential pressure proportional to said back pressure acting upwardly against said piston in opposition to said manually applied pressure and tending to move said valve member in a valve closing direction so that manual pressure is required to open said valve.

Claim 13

A manually operated fluid valve comprising: a valve block including a valve cavity extending inwardly of said block from a surface opening therein, a movable valve member movable axially within said cavity solely by manual pressure in a valve-opening direction and solely by fluid pressure in the opposite valve-closing direction, whereby said valve is characterized by the absence of springs for effecting movement of said valve member, said movable valve member including a valve piston movable axially within a first cavity section and including piston sealing means in fluid sealing engagement with the walls of said first cavity section to prevent escape of fluid from said surface opening, said movable valve member including a valve stem extending axially from a bottom surface portion of said piston within a second cavity section and including stem sealing means in fluid sealing engagement with the walls of said second cavity section and spaced axially from said piston sealing means, said stem sealing means being movable out of fluid sealing engagement upon movement of said piston under manual pressure in a valve-opening direction, a fluid inlet port in said block opening into said cavity upstream of said stem sealing means when said stem is in sealing engagement with said second cavity section, a fluid outlet port in said block opening into said cavity between said piston sealing means and said stem sealing means, whereby movement of said piston under manual pressure in a valve opening direction enables fluid flow from said inlet port into said valve cavity and past said stem sealing means into said outlet port, said stem and piston being sized such that fluid back pressure from said outlet port acting between said piston sealing means and said stem sealing means creates a variable differential pressure proportional to said back pressure acting upwardly against said piston in opposition to said manually applied pressure and tending to move said valve member in a valve closing direction so that manual pressure is required to open said valve.

Claim 14

A valve according to claim 11 wherein said piston and said stem comprise a one-piece said valve member.

Claim 15

A valve according to claim 11 wherein said second cavity section is of smaller diameter than said first cavity section and said inlet port is in a third cavity section of larger diameter than said second cavity section, sAid stem sealing means being movable from sealing engagement with the walls of said second cavity section into said third cavity section to enable fluid flow past said stem sealing means upon movement of said piston in a valve-opening direction under manual pressure.

Claim 16

A valve according to claim 11 wherein said piston is of larger diameter than the largest-diameter portion of said stem and has a larger bottom surface area against which back pressure acts than any opposed upper surface portion of said stem.

Claim 17

A valve according to claim 11 wherein said stem tapers gradually and progressively outwardly in an axial direction from its intersection with the bottom of said piston to said stem sealing means to provide a variable orifice within said cavity upon variable movement of said valve member.