US3608647A - Pressure-responsive fluid controlling system - Google Patents
Pressure-responsive fluid controlling system Download PDFInfo
- Publication number
- US3608647A US3608647A US47196A US3608647DA US3608647A US 3608647 A US3608647 A US 3608647A US 47196 A US47196 A US 47196A US 3608647D A US3608647D A US 3608647DA US 3608647 A US3608647 A US 3608647A
- Authority
- US
- United States
- Prior art keywords
- pressure
- valve
- back pressure
- outlet port
- piston
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
- B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
- B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers
Definitions
- Purser Attorney-0wen & Owen ABSTRACT A pressure responsive fluid control system for ;an air tool which is effective to shut off the tool when it reaches a predetermined torque and motor back pressure but will not prematurely react to temporary pressure increases 1 caused by motor inertia.
- A-back pressure sensitive valve has a face exposed to a fluid accumulator chamber whose volume is sufficient to absorb temporary pressure surges but which will increase in pressure to close the valve when the predetermined torque and back pressure are attained.
- the aforementioned Whitehouse patent avoids starting back pressure buildup through the use of a tapered, manually operated throttle valve. In that device, if the throttle valve is first cracked open and then gradually opened to admit maximum line airflow, the back pressure will not surge significantly enough to activate the controlling valve. This type of inhibiting device of course depends upon the skill of the tool operator and even if properly used, is slow in starting the tool.
- a control valve movable from an open to a closed position within a valve chamber, comprises a valve piston having a main line passage in fluid communication with an inlet port and an outlet port in the valve chamber when the valve is in its open position.
- the outlet port is in fluid communication with an air-driven motor.
- the valve piston comprises a head and a secondary piston head protruding from said head into an orifice in the base of the valve chamber, which orifice opens into an accumulator chamber.
- the valve piston is urged into its open position by a biasing spring.
- the accumulator chamber is in fluid communication with the valve outlet port through a restricted back pressure inlet and has a volume substantially larger than the volume of the back pressure inlet and the outlet port. Fluid flow through the back pressure inlet is thereby impeded and the corresponding pressurization rate of the larger accumulator chamber is shower than the pressurization rate of the outlet port.
- Air is admitted to said air-driven motor through the main line passage of the valve piston when said valve is in its open position. Due to inertia of the driven tool when said air motor is started, airflow through the main line passage and the outlet port is initially restricted. This temporarily restricted airflow creates a back pressure surge which pressurizes the accumulator chamber through said back pressure inlet at a rate slower than the surge rate at said outlet port.
- the back pressure in the accumulator chamber urges against the secondary piston head of said valve, but since the surge in said accumulator chamber is only temporary and increases at a rate slower than the back pressure increase at said outlet port (thus never reaching the maximum surge pressure reached at said outlet port) the biasing spring maintains said valve in its open position.
- the air motor meets increasing resistance (caused, for example, by increased torque loads on the air-driven tool) and thus back pressure increases at said outlet port, the accumulator pressure on said secondary piston head will increase to the point that said biasing spring is overcome thereby causing said valve piston to move toward its closed position.
- FIG. 1 is a schematic view of an air-driven motor, a fluidcontrolling device embodying the invention, and a throttle valve;
- FIG. 2 is a view in elevation of an air-driven motor with a fluid-controlling device embodying the invention and a throttle valve, showing the controlling valve in closed position;
- FIG. 3 is an elevational view similar to FIG. 2 but showing the controlling valve in open position
- FIG. 4 is a graph illustrating the operational characteristics of the present invention in connection with a torque-responsive air-driven tool.
- the valve 10 comprises a closed valve chamber 11 having an inlet port 12 and an outlet port 13, and a valve piston 14 movable within the valve chamber 11 from an open to a closed position.
- the valve piston 14 comprises a piston body 15 having a main line passage 16 in fluid communication with the inlet port 12 and the outlet port 13, a head 17, and a secondary piston head 18 protruding from the head 17 through an orifice 19 in an orifice plate 20, into an accumulator chamber 21 when the valve piston 14 is in its open position.
- the outside diameter of the secondary piston head 18 fits closely within the inside diameter of the orifice 19.
- the valve piston 14 is urged towards its open position by a bias spring 22 which is tensioned by an adjustable bias spring plug 23.
- the accumulator chamber 21 is in fluid communication with the outlet port 13 through a restricted back pressure inlet 24.
- the volume of the back pressure inlet 24 is substantially less than the volume of the accumulator chamber 21 and the volume of the outlet port 13. Fluid flow through the back pressure inlet 24 from the outlet port 13 is thereby significantly restricted. Furthermore, because of the dimensional relationship of the accumulator chamber 21 to the restricted inlet 24, changes in air pressure in the outlet port 13 will occur at a rate faster than corresponding changes in pressure in the 21 due to the impeded flow through the restricted inlet 24.
- Air from a pressurized source is introduced through the inlet port 12, the mainline passage 16 and the outlet port 13 to an air-driven motor 25 when the valve 10 is in its open position as shown in FIG. 3.
- an increasing work load e.g. increased torque resistance
- airflow through the motor 25 is impeded causing a corresponding back pressure increase at the outlet port 12 and in the accumulator chamber 21.
- back pressure in the accumulator chamber 21 urging against the secondary piston head 18, increases sufficiently to overcome the force of the bias spring 22, the valve piston 14 begins to move toward its closed position. (The initial-movement of the valve piston 14 places the piston head 17 in communication with the pressure in the chamber 21).
- valve piston 14 is under more force once said pistonhead 17 is thus exposed to the chamber 21.
- the valve piston 14 is thereby snapped towards its closed position, closing the mainline passage 16 between the inlet port 12 and the outlet port 13. As soon as the piston moves far enough to uncover a holding port 26, it is further urged towards and held in closed position by line pressure.
- FIG. 4 the operation of a torque responsive fluid controlling valve embodying the invention is illustrated on a graph.
- the inertia of the motor 25 initially impedes air flow, causing a back pressure surge, the peak of which is indicated on the motor back pressure curve at point a.
- the accumulator chamber 21 is in communication with the outlet port 13 through the restricted back pressure inlet 24, the chamber 21 is correspondingly pressurized by the back pressure surge, but at a significantly slower rate as shown on the pressure accumulator chamber curve. Due to this time-lag in pressurization of the accumulator chamber 21 and due to the relatively large volume of the accumulator chamber 21, the accumulator pressure remains below the motor back pressure when the back pressure increase is only momentary.
- the fluid-controlling valve 10 is thereby insensitive to sudden temporary increases in back pressure which would cause premature operation of said valve 10, but is fully responsive to predetermined pressures achieved through sustained loads on the air-driven motor 25.
- a control system for a tool driven by fluid under pressure effective to shut-off said tool when a predetermined back pressure is encountered by said control system caused by said tool encountering a predetermined load, but not responsive to momentary back pressure surges of less than said predetermined back pressure said control system comprising, in combination, a fluidtight valve housing, a fluid inlet port connecting a fluid pressure source to said housing, a fluid outlet port from said housing connected to an air motor driving said tool, a valve piston within said housing movable between (1) an open position at which fluid may pass from said inlet port through said housing to said outlet port and (2) closed position at which communication between said inlet and outlet shut-off said tool when a predetermined back pressure is encountered by said control system caused by said tool encountering a predetermined load, but not responsive to momentary back pressure surges of less than said predetermined back pressure, said control system comprising, in combination, a fluidtight valve housing, a fluid inlet port connecting a fluid pressure source to said housing, a fluid outlet port from said housing connected to an air motor driving
- a control system for a tool driven by fluid under pressure according to claim 1 wherein the volume of said accumulator chamber is substantially greater than the volume of said restricted means connecting said outlet port to said chamber whereby the back pressure in said chamber achieved through said restricted means increases at a rate slower than the back pressure increase rate at said outlet port.
- a control system for a tool driven by fluid under pressure according to claim 2 wherein said restricted means connecting said outlet port to said accumulator chamber has a volume substantially less than the volume of said outlet port whereby the back pressure in said chamber increases at a rate slower than the back pressure increase rate at said outlet port due to an impeded fluid flow rate from said outlet port into said chamber through said restricted means.
- a pressure responsive fluid-controlling system wherein said bias means includes a spring and means for adjusting the tension of said spring to maintain a pressure upon said valve piston substantially equal to a predetermined accumulator chamber back pressure.
- insert --port is placed-influid communication with the valve piston heac i, causin g said-valve p'istonto snap into its closed position, closing the main line passage to thus shut off air flow to the mot OI'I" Column? liinei” 18, efter the, insert -'-chamber--,
- control system-for a' tool driven by fluid under pressure effective to shut-off said tool when a predetermined back pressure is encountered by said control system caused by said tool encountering a predetermined load, but not responsive to momentary'back pressure surges of less than said predetermined back pressure, said control system comprising, in combination,
- a fluid-tight valve housing a fluid inlet port connecting a fluid pressure source ;to said housing, a fluid outlet port from said housing connected to an .air motor driving said tool, a I valve piston within said housing-movable between (1) an open position at which fluid may pass from said inlet-port through; said housing .to said outlet portand (2) a closed position at which communication between said inlet and outlet ports is shutoff, means biasing said valve piston toward its saidopen position, said valve piston having ahead and a secondary piston head of reduced area protruding from said head through an orifice plate at one end of said valve housing into an accumulator chamber, said chamber having a volumesufficient to prevent a temporary air surge from reaching said predetermined back pressure value, restricted means connecting said outlet port 'to said accumulator chamber whereby pressure therein will increase inresponse tom-increased back-pressure caused in said motor but at a rate slower than the initial back-pressure increase at the outlet 'port', said orifice plate separating said accumulator chamber from said valve
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
Abstract
Description
Claims (4)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US4719670A | 1970-06-18 | 1970-06-18 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3608647A true US3608647A (en) | 1971-09-28 |
Family
ID=21947588
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US47196A Expired - Lifetime US3608647A (en) | 1970-06-18 | 1970-06-18 | Pressure-responsive fluid controlling system |
Country Status (1)
Country | Link |
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US (1) | US3608647A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3904305A (en) * | 1974-08-19 | 1975-09-09 | Cooper Ind Inc | Speed sensing air tool shutoff |
US4004859A (en) * | 1975-08-18 | 1977-01-25 | Cooper Industries, Inc. | Air tool with speed responsive shutoff |
US4120604A (en) * | 1977-04-29 | 1978-10-17 | Garofalo Nicholas J | Portable pneumatic nut running tool having air shut-off controls |
US4243111A (en) * | 1979-01-31 | 1981-01-06 | Ingersoll-Rand Company | Automatic shut-off valve for power tools |
US4492146A (en) * | 1982-07-26 | 1985-01-08 | Cooper Industries, Inc. | Shut-off device for a fluid driven motor |
US4721166A (en) * | 1986-03-21 | 1988-01-26 | Ingersoll-Rand Company | Automatic shut-off valve for power tools |
US11225986B2 (en) * | 2019-02-27 | 2022-01-18 | Hold Well Industrial Co., Ltd. | Pneumatic control device |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3373824A (en) * | 1965-11-24 | 1968-03-19 | Stanley Works | Fluid operated tool |
US3505928A (en) * | 1967-07-21 | 1970-04-14 | Stanley Works | System for performing tool operation and signaling completion thereof |
-
1970
- 1970-06-18 US US47196A patent/US3608647A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3373824A (en) * | 1965-11-24 | 1968-03-19 | Stanley Works | Fluid operated tool |
US3505928A (en) * | 1967-07-21 | 1970-04-14 | Stanley Works | System for performing tool operation and signaling completion thereof |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3904305A (en) * | 1974-08-19 | 1975-09-09 | Cooper Ind Inc | Speed sensing air tool shutoff |
US4004859A (en) * | 1975-08-18 | 1977-01-25 | Cooper Industries, Inc. | Air tool with speed responsive shutoff |
US4120604A (en) * | 1977-04-29 | 1978-10-17 | Garofalo Nicholas J | Portable pneumatic nut running tool having air shut-off controls |
US4243111A (en) * | 1979-01-31 | 1981-01-06 | Ingersoll-Rand Company | Automatic shut-off valve for power tools |
US4492146A (en) * | 1982-07-26 | 1985-01-08 | Cooper Industries, Inc. | Shut-off device for a fluid driven motor |
US4721166A (en) * | 1986-03-21 | 1988-01-26 | Ingersoll-Rand Company | Automatic shut-off valve for power tools |
US11225986B2 (en) * | 2019-02-27 | 2022-01-18 | Hold Well Industrial Co., Ltd. | Pneumatic control device |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: R.T. ACQUIRING CORP., A CORP. OF, DELAWARE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:COOPER INDUSTRIES, INC.;REEL/FRAME:003841/0981 Effective date: 19810113 Owner name: R.T. ACQUIRING CORP., A CORP. OF DE. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COOPER INDUSTRIES, INC.;REEL/FRAME:003841/0981 Effective date: 19810113 |
|
AS | Assignment |
Owner name: ROTOR TOOL CORPORATION, OHIO Free format text: CHANGE OF NAME;ASSIGNOR:R.T. ACQUIRING CORP.;REEL/FRAME:003844/0231 Effective date: 19810113 Owner name: ROTOR TOOL CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:R.T. ACQUIRING CORP.;REEL/FRAME:003844/0231 Effective date: 19810113 |
|
AS | Assignment |
Owner name: NATIONAL ACCEPTANCE COMPANY OF CALIFORNIA, A CA CO Free format text: SECURITY INTEREST;ASSIGNOR:ROTOR TOOL COMPANY, THE;REEL/FRAME:005251/0105 Effective date: 19861219 |