Motors: expansible chamber type – Fluid supply through diverse paths to single expansible chamber – Serially arranged reversing valves
Reexamination Certificate
1998-12-31
2001-02-27
Ryznic, John E. (Department: 3745)
Motors: expansible chamber type
Fluid supply through diverse paths to single expansible chamber
Serially arranged reversing valves
C091S031000, C091S032000, C091S428000, C091S444000
Reexamination Certificate
active
06192781
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to tools, such as automatic drills, and more particularly, to a method and apparatus for reversing a fluid driven motor of such tools.
2. Description of the Related Art
Fluid driven motors, such as air driven or liquid driven motors, are widely used in industry, particularly in portable tools. For example, radial vane air motors, or pneumatic motors, are used in portable air tools, such as nut runners and right angle positive feed drills. In many instances, it is desirable to reverse the motor of such tools. For instance, with some right angle positive feed drills, reversing the air motor causes a spindle and drill bit to rapidly advance toward a workpiece. Rapidly advancing the drill bit toward the workpiece saves considerable time because, without the rapid advance option, an operator of the tool must wait for the spindle to advance slowly toward the workpiece during a drilling cycle. Hence, many conventional tools include an air motor that is reversible.
Conventional reversible air motors typically include a bearing plate having an axially oriented inlet port and an axially oriented outlet port. Such air motors are run in a forward direction by directing air flow through the inlet port and by permitting exhaust air to exit the outlet port. To reverse such air motors, the air flow is shut off and the air porting is changed such that air will flow into the outlet port rather than the inlet port. In this case, the motor will turn in reverse and the inlet port will function as an exhaust port. This rerouting of the the air flow is typically achieved by an operator manually moving a switch or other similar device to directly move a ring located adjacent to the bearing plate having the inlet and outlet ports. After the operator has reversed the porting, the air supply is turned on to run the motor in reverse. Thus, two manual steps are required to reverse the air motor.
Other conventional tools use other approaches to reverse an air motor. For example, one such tool includes what is typically considered a non-reversible air motor. This air motor includes an axially oriented inlet port, but does not include an axially oriented outlet port as it is typically designed to rotate in one direction. Thus, the air motor includes a plurality of exhaust slots located along the periphery of air motor's housing. This air motor is run in a forward direction by directing air flow through the inlet passage and out of the above-described exhaust ports. To reverse this type of air motor, a shifting lever is actuated by an operator, which opens a ball valve. The opening of the ball valve permits pressurized air to flow into a deflector cavity. The pressurized air in the deflector cavity imposes a force against a pressure-actuated exhaust deflector that is slidably mounted on the outside of the motor housing. The exhaust deflector is moved and closes off the atmospheric exhaust route normally used during forward rotation of the motor. The incoming pressurized air in the deflector cavity is then routed to the normal exhaust slots of the motor such that the motor operates in reverse. Although this reversing method adequately reverses the motor of the tool, it requires many complicated parts in order for the reversing operation to function properly. For instance, the above-described construction requires kick-out springs in the motor to keep the blades thrown against the wall of the motor.
In yet another conventional approach to reversing an air motor of a tool, an operator actuates a button to cause a spool valve to reroute air flow to the inlet and outlet ports of a reversible air motor. However, this approach tends to reduce the power of the air motor, unless the spool valve is overly large. Additionally, this approach of reversing the air motor requires that the operator turn on the flow of pressurized air to the motor by actuating another device, such as an air valve.
Thus, it is apparent that conventional tools having a reversible air motor generally require two separate steps to reverse the motor—reversing the porting to the motor, and then supplying air to the motor to run it in reverse. These separate steps may create manufacturing problems and even damage the tool if the operator performs these steps in the wrong order or in combination with another sequence, such as a drilling cycle. Furthermore, conventional tools having an actuator that both reverses the porting to and from the air motor and supplies air to the motor are overly complicated. The above-described constraints and problems associated with conventional tools has created a need for a new approach to reverse an air motor.
SUMMARY OF THE INVENTION
Generally speaking, the present invention provides an assembly for reversing a fluid driven motor, such as an air motor or a liquid driven motor.
According to one aspect of the present invention, an assembly for reversing an air motor includes a housing having an air supply channel, and an air motor having a first air passageway and a second air passageway. The air motor rotates in a first direction when air is supplied to the first air passageway from the air supply channel. The air motor rotates in a second direction opposite to the first direction when air is supplied to the second air passageway from the air supply channel. A reversing valve is pneumatically moveable from a first position to a second position. The reversing valve has at least one port that communicates the air supply channel with the first air passageway when the reversing valve is located in the first position. The reversing valve prevents air flow from the air supply channel to the first air passageway and communicates the air supply channel with the second air passageway when the reversing valve is located in the second position. The reversing valve moves from the first position to the second position when an actuation valve opens. The reversing valve is movable from the second position back to the first position when the actuation valve closes. An air supply valve communicates the air supply channel with one of the first air passageway an the second air passageway when the air supply valve opens. An actuation device opens the actuation valve and the air supply valve.
According to another aspect of the present invention, an assembly for reversing a fluid driven motor includes a fluid driven motor, and a reversing valve for reversing an inlet port to the motor and an exhaust port from the motor. The assembly further includes an openable and closeable actuation valve, an openable and closeable fluid supply valve, and an actuation device for opening the actuation valve and the fluid supply valve. The actuation valve causes the reversing valve reverse the inlet and exhaust porting to and from the fluid driven motor when the actuation device opens the actuation valve. The fluid supply valve allows fluid to flow through the fluid supply valve to the motor when the actuation device opens the fluid supply valve. The fluid supply valve prevents fluid flow through the fluid supply valve to the fluid driven motor when the fluid supply valve is closed.
In accordance with another aspect of the present invention, an assembly for reversing a fluid driven motor includes a fluid driven motor, and a throttle valve in communication with a fluid flow supply channel located upstream of the throttle valve with respect to a direction of fluid flow. The throttle valve is openable and closeable. The throttle valve directs fluid flow to the motor from the fluid flow supply channel to rotate the motor in a forward direction when the throttle valve is opened. An actuation valve causes a reversing valve to reverse an inlet port to the motor and an exhaust port from the motor when the actuation valve is actuated. The actuation valve is in communication with the fluid supply channel at a location upstream of the throttle valve.
According to a further aspect of the present invention, an assembly includes a fluid driven motor. The motor has a rear bearing pl
Fowler Robert E.
Thames Bruce A.
Coats & Bennett PLLC
Cooper Technologies Company
Ryznic John E.
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