Power tool with fluid boost

A method of rotatably driving a fastener into a workpiece using a power tool including a fluidically-driven motor, comprising the steps of:

• admitting pressurized fluid into the motor via a first delivery path disposed in the power tool;
• and
• upon sensing a change in resistance in the workpiece to driving the fastener, selectively also admitting air into the motor via a second delivery path to augment the volume of fluid delivered via the first delivery path;
• whereby the fastener may be driven without using a clutch mechanism operatively associated with the motor and the fastener.

A method for conserving pressurized air delivered to a dual-chamber air motor disposed in a power tool having a tool element and connected to a source of air at a predetermined pressure, comprising the steps of:

• actuating a first stage of a multi-stage throttle-actuated dual-ported mechanism disposed in the power tool to admit air at a predetermined volume into the motor via a first port in the mechanism;
• wherein
• the first port is sized to restrict the volume of air flow into the motor so that the motor drives the tool element within a predetermined range of speed and torque;
• and
• selectively actuating a second stage of the mechanism to admit air into the motor via a second port in the mechanism to augment the volume of air admitted into the motor by the first port.

A method for driving the rotary output member of a fluidically-driven power tool having a motor, comprising the steps of:

• connecting the power tool to a source of pressurized fluid;
• actuating a primary throttle disposed in the power tool to admit fluid via a first delivery path into the motor to rotate the output member at a predetermined speed;
• sensing a drop in the speed of the output member;
• and
• actuating a secondary throttle disposed in the power tool to subsequently admit fluid via a second delivery path into the motor, to resume driving the output member at the predetermined speed, without having to increase the pressure of the fluid in the source of pressurized fluid.

A throttle system for a fluidically-powered power tool, comprising:

• a fluidically-powered motor disposed in the power tool;
• a primary throttle operatively associated with a secondary throttle and the motor;
• the primary and secondary throttles being disposed in the power tool;
• a source of pressurized fluid being connected to the primary and secondary throttles;
• the primary throttle including a throttle sleeve defining an axis, and a primary throttle stem axially moveable in the throttle sleeve inwardly from a first predetermined axial position to a second predetermined axial position and to a third predetermined axial position, the stem being normally biased axially outwardly to the first predetermined axial position;
• wherein
• in the first predetermined axial position, no pressurized fluid is admitted to the motor;
• in the second predetermined axial position, pressurized fluid is admitted to the motor via a first delivery path;
• and wherein
• in the third predetermined axial position, pressurized fluid is admitted to the motor from the secondary throttle via a second delivery path to augment the volume of pressurized fluid provided by the primary throttle.

An air-driven power tool, comprising:

• a housing including a motor portion, a drive system portion and a handle portion;
• an air motor defining an axis and being mounted in the motor portion of the housing;
• a drive system operatively associated with the motor and including an output spindle, the drive system being mounted in the drive system portion of the housing;
• a throttle system operatively associated with the motor and mounted in the housing, and being connectable to a source of pressurized air;
• an actuator moveably connected to the handle portion and being engageable by an operator;
• wherein
• the actuator being operatively associated with the throttle system, such that when the actuator is moved from a first axial position to a second axial position relative to the handle portion, pressurized air is admitted into the motor via a first delivery path, and when the actuator is moved to a third axial position relative to the handle portion, pressurized air is also admitted into the motor, via a second delivery path, to augment the volume of air delivered to the motor via the first delivery path.

A rotary air motor for an air-driven power tool, comprising:

• a cylinder sleeve defining an axis and having a front and rear, and further defining a plurality of axial air passages extending from the front to the rear;
• a front end plate connected to the front of the cylinder sleeve and to a front bearing;
• a rear end plate connected to the rear of the cylinder and to a rear bearing;
• a rotor rotatably mounted in the cylinder sleeve along the cylinder sleeve axis and disposed between the plates and further being rotatably connected to the bearings;
• a plurality of air vanes radially moveably connected to the rotor;
• wherein the cylinder sleeve and rotor defining an eccentric motor air chamber;
• the cylinder sleeve further defining a plurality of generally radial air inlets for admitting pressurized air having a predetermined volume into the motor air chamber, the generally radial air inlets being in fluid communication with respective axial air passages formed in the cylinder sleeve;
• the rear end plate defining internal air passages for receiving the pressurized air from the axial air passages and for directing the air at the air vanes adjacent the rotor to bias the air vanes radially outwardly and to rotate the air vanes;
• and wherein
• the rear end plate further defining an axial air boost inlet for admitting pressurized air into the motor air chamber to augment the volume of air admitted to the motor air chamber.

A method for replacing a transmission stage of an air-powered power tool that drives a tool bit in a predetermined range of desired rotational speeds at a predetermined range of desired torque, comprising:

• providing the power tool with a dual-chamber rotary air motor including two opposed eccentric air chambers, and further including a rotor defining a drive pinion;
• providing the power tool with an air throttle to selectively admit a predetermined volume of pressurized air to the air chambers via a first delivery path and, upon actuation by an operator, to additionally simultaneously admit boost air to the air chambers via a second delivery path to augment the volume of pressurized air admitted to the air chambers via the first delivery path;
• whereby
• the power tool is capable of delivering output power to the tool bit in ranges at least equivalent to those delivered by an air-powered power tool having the transmission stage, even when the tool bit encounters such resistance in a workpiece as would otherwise tend to cause the power tool to stall.

A method for minimizing the length and weight of an air-driven power tool for driving an output member, comprising:

• drivingly connecting a dual chamber air motor to drive the output member at a predetermined speed;
• providing a valve system in the power tool that is operatively associated with the air motor to selectively boost the volume of pressurized air delivered to the motor;
• wherein
• the air motor includes a cylinder sleeve disposed between front and rear end plates;
• and wherein
• pressurized air is admitted to the dual air chambers via inlets in the cylinder sleeve, and pressurized air is also selectively admitted to the air chambers via inlets in one of the end plates.

An air exhaust system for an air-driven power tool, comprising;

• a housing including a motor portion, a drive system portion disposed axially forwardly of the motor portion, and a handle portion;
• an air-driven motor drivingly connected to an output spindle and disposed within the motor portion and defining an air exhaust port;
• a motor air exhaust chamber formed in the motor portion of the housing around the motor;
• the motor air exhaust port being in fluid communication with the motor air exhaust chamber;
• an interior primary exhaust air passage disposed in the housing in fluid communication with the motor air exhaust chamber for normally conveying exhaust air from the exhaust chamber to ambient atmosphere;
• an interior auxiliary exhaust air passage formed in the drive portion of the housing and in fluid communication with the primary air exhaust passage for selectively diverting a portion of the exhaust air from the motor air exhaust chamber axially forwardly;
• and
• an exterior auxiliary exhaust air port formed in the drive system portion of the housing and being in fluid communication with the interior auxiliary air passage.