US2726677A - Governor valve for fluid actuated rotary tool - Google Patents

Description

Dec. 13, 1955 s. E. REES 2,726,677

GOVERNOR VALVE FOR FLUID ACTUATED ROTARY TOOL Filed Sept. 22, 1954 2 Sheets-Sheet l INVENTOR. jfiro osfi/re E. Rees ATTORNEY Dec. 13, 1955 s. E. REES 2,726,677

GOVERNOR VALVE FOR FLUID ACTUATED ROTARY TOOL Filed Sept. 22, 1954 2 Sheets-Sheet 2 I Z 60 52 3 5/ 43 36 46 K 69 6249 50 56 35 57 64 INVENTOR.

72 J/YrcJ OJfi/re E. Rees A TTORNf Y United States Patent GOVERNOR VALVE FGR FLUID ACTUATED RGTARY TOOL Shropshire E. Rees, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex, a corporation of Texas Application September 22, 1954, Serial No. 457,664

8 Claims. Cl. 137-494 This invention relates broadly to fluid actuated tools, but more particularly to an improved governor valve for fluid actuated rotary tools such as grinders, screw drivers, impact wrenches and the like.

One object of this invention is to provide such tools with means responsive to the load to which the tool is subjected for automatically governing its rotary speed.

Another object of this invention is to produce an eflicient and reliable valve for automatically regulating the supply of motive fluid to the tool with which the valve is associated as it encounters varying loads or resistance to rotation.

Another object of this invention is to produce a device causing such rotary tools to operate at top speed when subjected to normal working loads and at a greatly reduced speed when idling or operating under a light load.

A still further object of this invention is to provide an improved speed governor for fluid actuated rotary motors.

Other objects and novel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawings, wherein:

Figure l is a longitudinal sectional view of a portion of a rotary tool embodying the invention.

Figures 2, 3 and 4 are similar enlarged longitudinal views of the governing valve mechanism shown with parts in different positions.

Figure 5 is a cross-sectional view taken on line 5-5 in Figure l and looking in the direction of the arrows.

Referring to the drawings, 19 designates generally the back end of a fluid actuated motor or rotary tool to which is aflixed by any suitable means a handle generally designated by 12. More particularly, tool consists of a cylinder 13 in which is fixed between two end plates 14 and 15 a stator 16. As usual in tools of this type, stator 16 is provided with a rotor chamber 17 extending the full length thereof in which is eccentrically mounted a rotor 18 having shafted end portions, such as 19, rotatably supported within end plates 14 and 15 preferably in suitable bearings, such as 20. Rotor 18 carries radially movable vanes 21, which when subjected to motive fluid admitted into the stator through suitable opening such as inlet slot 22, impart rotation to the rotor. As will be understood by those skilled in this art, rotor 18 either has a shaft which extends through the front end of the tool, not shown, or is operatively associated with any suitable driving mechanism for imparting rotary motion to a work performing tool.

' Handle 12 is also of the usual type preferably screwed to cylinder 13 by bolts 23. Briefly this handle includes a handle grip portion 24 adapted to be grasped by the user for holding the tool to the work. A pivotally mounted trigger 25 operable by the user acts on a push rod 26 for opening a throttle valve 27 which is normally urged on its seat or in closed position relative to an inlet port 28 by a compression spring 29. As shown, throttle valve 27 and spring-29 are housed within a bushing 30 2,726,677 Patented Dec. 13, .1955

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which has one end screwed within the handle and the other end formed with an internally threaded connection 31 adapted to receive one end of a motive fluid conveying conduit, not shown. Valve controlled port 28 opens into the inner end of bushing 30 which communicates through radial ports 32 with a handle inlet passage 33 opening into an inlet or first chamber 34.

Near its rear end, cylinder 13 is provided with a longitudinally extending external boss 35 having a cylindrical bore 36 extending axially therethrough in which is pressed or otherwise secured a bushing or sleeve 37. This sleeve has inlet slot 38 aligned with the slot 22 through which motive fluid may be supplied to the rotor chamber 17. Rotatable within the portion of sleeve 37 furtherest away from handle 12, there is a conventional reversing valve 49 having a handle 41 fixed to one end by a cross pin 42 and provided with sockets adapted to receive a spring pressed detent 43 for holding the valve in at least two predetermined positions. The other end 44 of the reversing valve falls short of the end of the sleeve and has a motive fluid conveying passageway or second chamber 45 leading therefrom to a slot 46 adapted to register with the slot 38. As hereinafter explained, motive fluid is admitted into second chamber 45 and therefrom through the valve slot 46 into the rotor chamber 17 through slots 38 and .22 for effecting rotation of rotor 18 in one direction. Valve 40 may be rotated to another position for similarly supplying motive fluid into rotor chamber 17 but through different slots corresponding to 38 and 22 for eflective rotation of rotor 18 in another direction. In other words, the primary function of the reversing valve 40 is to control the direction of rotation of the motor.

.Referring now more particularly to the invention, within the other end portion of sleeve 37 is pressed or otherwise secured the cylindrical skirt 48 of a valve casing 55) which extends into chamber 34 and intermediate its ends is provided with an external annular shoulder 49 resting against the inner end of sleeve 37. The inner end of the skirt 48 is spaced sufliciently from the adjacent end of the reversing valve 40 to provide a clearance 70 preventing interference with rotation of the valve. A bore 51 formed with a deep counterbore or enlarged end portion 52 extends centrally through casing 50, the counterbore 52 constituting a cylindrical chamber into which opens the main passage or second chamber 45 of the reversing valve 41). This chamber, at its junction with bore 51, forms an annular shoulder 53 against which is adapted to rest the annular head 54 of an outer piston element 55 slidable within the other end portion of casing bore 51 and having fixed on its free end, outside of casing 50, a nut or stop 56 threaded thereon and retained by a cross pin 57. An inner piston element 58 is slidable within the outer one and has its inner end counterbored to receive one end of a compression spring 59 which has its other end seated on the bottom of a similar counterbore provided within a governor valve 60 slidably mounted within chamber 52. Governor valve 66 has a reduced outer end engageable with a second stop formed by the inner end of reversing valve 40. This outer end together with the surrounding area constitute a valve pressure surface 61.

Immediately below the casing annular shoulder 49, sleeve 37 is provided with a relatively narrow annular groove 62 in communication with the portion of cylin drical chamber 52 adjacent the internal shoulder 53 through radial ports 64, while the groove 62 is in constant communication with the outside of cylinder 13 through one vent hole 65. Adjacent its inner end, casing skirt 48 is provided with radial ports 47 and 66 opening into cylindrical chamber 52 and into an annular groove 67 drive it rearwardly to contact the cross pin 57.

after. both inner and outer piston elements 58 and 55 will i be moved by spring 59. away from governor valve 69' formed within sleeve 37, which groove is in constant communication with first chamber 34 through a passage-way 68. The radial portor primary inlet 47 opens into chamber 52 closer to the free end thereof than the radial port orsecondary inlet 66. V

Groove 67 is inconstant communication with the end of cylindrical chamber 52 adjacent reversing valve 40 through a small clearance 69 around the inner end of skirt 48 and clearance 70 between the adjacent ends of the skirt and reversing'valve' Port 68 extends beyond annular groove 67 into avalve controlled port 71 which opens into clearances 69'and'70,with the opening of port 63 thereinto controlled by a manually operable screw valve 72. V Theoperation'of the device is as follows: When the throttle valve 27 is closed as shownin Figure l and no pressure fluid is admitted into chamber 34, the compresend or actuating area of outer piston element 55 also subjected to built-up pressure within chamber 34 will cause the piston to move inwardly until its stop 56 contacts the free end of valve casing 50 as clearly shown in Figure 2.

As load is applied to the tool, that is, when resistance to rotation of rotor 18 is increased, it will cause fluid pressure to build up within rotor chamber 17, which builtup or increased pressure will act on the governor valve pressure surface 61. When the resulting force is sntficient to overcome the combined forces of the spring 59; and inner piston 58 acting on the opposite side of the valve,

it will shift valve 60 away from reversing valve 40 into,

* engagement with the inner end 54 of outer piston 55,by

sion spring 59 acting on the inner piston element 58 will 1 Thereuntil the annular head 54 of outer piston element 55 contacts the annular shoulder 53. Concurrently the governor valve 60 also acted upon by spring 59 will be moved into'the outer end of chamber 60 into contact with the inner end of the reversing valve 4i). In this position of the three parts of the governing device, any pressure fluid previously admitted by leakage between the several sliding fits intothe inner'end of'chamber 52, is free to exhaust therefrom through radial ports 64, annular groove 62 and vent 65. It will thus be understood that the inner end ofchamber 52 is always atatmospheric pressure and 1 that the ports 64, groove 62 and vent 65 provide venting meanspreventing pressure build-up against the inner end of governor valve 60 andthe'adjacent inner ends of the piston elements 58 and 55.

With the governor valve 60 in the position shown in Figures' l and 2, that is, when the valve is at the end of its outward travel within chamber 52, the pressure fluid supplying primary and secondary ports,47 and 66 are closed by the valve, thereby enabling upon opening of the throttle valve 27, pressure fluidfrom first chamber 34, and conveying passage 68 to be supplied to the main passage or second chamber 45 of the reversing valve 40 only'through the clearances 69 and 70. The amount of pressure fluid thus supplied to the second chamber 45,

pushing inner piston 58into the outer one, as clearly shown in Figure 3. Although the fluid pressure, at this time, acting on the entire pressure surface 61 of governor valve 60 is smaller than the pressure acting on the outer end or actuating area of inner piston 58, the area of that surface is sufliciently greater than that of the outer end 7 of inner piston 58, thereby resulting in an effective pressure capable of moving inner piston 58 into. the outer piston 55. However, this efiective force is not at this I time'capable of overcoming the combined pressure on the outer ends or actuating areas of both pistons 54 and 58,

which from there is free to flow to the rotor chamber 17 through supply slots such as 46, 38 and 22 to impart rotation to rotor 18, is relatively small but sufficient to operate the motor or tool at a normal freespeed. An

increase or decrease of the motor free speed may be ob tained by varying the sizesof the clearances 69 and 70. To that end, the screw valve 72 may be screwed more Q 7 or less into the, port 71 for controlling the effective open- 'ingof passage-way 68 into port 71, and thereby providing up within chamber 34 to act on the outer end or actuating area of inner piston element 58 and drive it forwardly to shift and maintain governor valve 60 into engagement with reversing valve 40 and in closed position relative to ports 47 and 66.

.Upon opening of the throttle valve 27 and sufiicient pressure built-up in the chamber 34, this shifting of the inner piston element 58 also takes place when the spring 59. is used. In instance, piston 58 cooperates with spring 59 to maintain governor valve in closed position relative to inlet ports 47 and 66. Concurrently, the outer thereby causing the governor valve 60 to remain temporarily in the intermediate position relative to the ends of-chambef 52, in which position primary inlet port 47 is uncovered by the valve while secondary port 66 is still closed. As additional pressure fluid is supplied to the rotor chamber through primary inletport 47, greater pressure build up takes place in the rotor chamber 17 and consequently on the pressure surface 61 of the governor valve 60, thereby overcoming the combined pressure. on the outer ends or actuating areas or" both piston elements 55 and '58 and causing them to be shifted by the'valve' into their outermost positionwithin casing 50, that is, in engagement of the piston head 54 with the internal annular shoulder 53, while the valve assumes its innermost position within chamber 52 as shown in Figure 4. In'this last position of the governor valve, it uncovers the secondary inlet port 66 for admitting adequate additional pressure fluid into rotor chamber 17 for operating motor at full capacity and full load.

During operation of the tool, when the load is removed,

less pressure in the rotor chamber 17 is needed to impart'rotation to rotor18, thereby resulting in a faster exhaust of pressure fluid from rotor chamber 17 and a consequential drop of pressureiin that chamber and in the outer end of chamber 52. Since the pressure in the inlet chamber 34 remains substantially constant, it will overcome the decreasing pressure acting on the governor,

valve 60 and will drive both piston elements. 55 and 58 inwardly of casing 50 and valve 60 outwardly within chamber 52 until piston stop 56 contacts the free end of casing 50, in which instance the secondary inlet port 66 is closed by the valve. As ,a result of this port being; closed, less pressure fluid is admitted into rotor chamber 17, and since no load is applied to the motor, a further reduction of the fluid pressure will take place within rotor chamber 17 and on the end face of valve 60, causing constant fluid pressure within chamber 34 to drive inner piston 58 and valve 60 toward the reversing valve 40 imtil valve 60 reaches the end of its outward travel within chamber 52. In this final position of the valve 60, the

primary inlet port 47 is againclosed bythe valve, thereby I limiting. supply of pressure fluid to the rotor 18 through clearances 69 and 70 for etfecting normal free speed ofthe motor. I a V Depending upon the size and capacity of the toolor motorwith which the governing device above described is to be used, the size of the ports 47 and 66 may bevaried,

or preferably their number may be increased to supply the required amount of pressure fluid to the rotor chamber 17 for operating the rotor at full capacity..

From the foregoing description, it will be understood that the invention provides a speed governing device automatically controlling the free speed of the rotary motor with which it is associated, which free speed may be further controlled by the screw valve 72. It will also be understood that under certain conditions of operation, that is, when a predetermined load is applied on the tool, the device automatically supplies additional pressure fluid to the motor through port or ports 47, and when the tool is finally subjected to its full load, the device automatically responds by supplying still more pressure fluid through the port or ports 66. As load is removed from the tool, the governing device functions in reversed order to gradually reduce the amount of pressure fluid supplied to the rotor 18.

The details of structure and arrangements of parts shown and described may be variously changed and modified without departing from the spirit and scope of the invention.

I claim:

1. In a device of the character described, an inlet chamber having pressure fluid admitted therein, a pressure fluid conveying passage-way, a casing with a bore therethrough having a first end portion opening into said chamber and a second end portion enlarged and opening into said passage-way, an outer piston element slidable within the first end portion of said bore with its inner end within the second portion thereof, stop means limiting inward and outward movements of said element within said bore, an inner piston element slidable within said outer one, primary and secondary pressure fluid supplying means opening into the enlarged portion of said bore, a valve slidable within said enlarged portion, means uncontrolled by said valve supplying limited amount of pressure fluid from said chamber to said passage-way, spring means normally maintaining said valve closed relative to the openings of said primary and secondary means, said inner piston element shifted against said valve by pressure fluid within said chamber acting on one end thereof to assist said spring means, said outer piston element similarly shifted into its innermost position within said casing, a pressure surface on said valve subjected to fluid under increased pressure within said passageway overcoming opposed pressure of said spring means and inner piston element to shift said valve against the inner end of said outer piston element into open position, relative to the opening of said primary means and supplying additional pressure fluid to said passage-way, said valve pressure surface being responsive to fluid under still greater pressure within said passage-way for overcoming opposed combined pressure of said spring means and piston elements to shift said valve and elements into the outermost position of the elements within said casing and into open position of said valve relative to the opening of said primary and secondary means to supply still more pressure fluid to said passage-way.

2. In a device of the character described, an inlet chamber having pressure fluid admitted therein, a pressure fluid conveying passage-way, a casing with a bore therethrough having a first end portion opening into said chamber and a second end portion enlarged and opening into said passage-way, an outer piston element slidable within the first end portion of said bore with its inner end within the second portion thereof, stop means limiting inward and outward movements of said element within said bore, an inner piston element slidable within said outer one, primary and secondary pressure fluid supplying means opening into the enlarged portion of said bore, a valve slidable within said enlarged portion, means uncontrolled by said valve supplying limited amount of pressure fluid from said chamber to said passage-way, said piston elements being shifted inwardly within said casing by pressure fluid within said chamber acting on adjacent ends thereof with said inner element shifting said valve into closed position relative to'the opening of said primary and secondary means, a pressure surface on said valve subjected to fluid under increased pressure within said passage-way to overcome opposed pressure of said inner piston element and shift said valve against the inner end of said outer piston element into open position relative to the opening of said primary means, said valve pressure surface being responsive to fluid under still greater pressure within said passage-way to overcome opposed combined pressure of said piston elements and shift said valve into open position relative to the openings of said primary and secondary means and said elements into their outermost position within said casing.

3. In a device of the character described, a first chamber having pressure fluid admitted therein and a second chamber, a casing with a bore therethrough having a first end portion opening into said first chamber and a second end portion enlarged and opening into said second chamber, outer and inner piston elements slidable within said first end portion one within the other with their inner ends within said second end portion, first stop means limiting slidable movement of said outer piston element in both directions, primary and secondary pressure fluid conveying means from said first chamber opening into said second end portion, a valve slidable within said second end portion limited inwardly by the inner end of said outer piston element, second stop means limiting said valve outwardly to assume a closed position relative to the openings of said primary and secondary means, means supplying small amount of pressure fluid from said first to said second chamber, said piston elements being shifted inwardly of said casing by pressure fluid in said first chamber acting on adjacent ends thereof causing said inner element to engage the inner end of said valve and shift the valve into engagement with said second stop means, a pressure surface on said valve subjected to fluid under increased pressure within said second chamber and capable of overcoming opposed pressure from said inner piston element to shift said valve against the inner end of said outer piston element and into open position relative to the opening of said primary means, said valve pressure surface being subjected to fluid under still greater pressure within said second chamber thereby overcoming the opposed pressure of said inner and outer piston elements to shift said valve into open position relative to the openings of said primary and secondary means and concurrently shift said elements into their outermost position within said casing.

4. A device according to claim 3, in which manually operable valve means is provided to control said small amount of pressure fluid admitted from said inlet to said outlet chambers.

5. A device according to claim 3, in which vent means is provided for constantly subjecting the inner ends of said piston elements and valve to atmospheric pressure.

6. In a device of the character described, a first chamber having pressure fluid supplied therein and a second chamber, a casing between said chambers with a bore therethrough, inner and outer piston elements slidable the former within the latter and within a first portion of said bore, a valve slidable within a second portion of said bore, pressure fluid conveying means from said first to said second chamber controlled by said valve, actuating areas on said piston elements subjected to pressure fluid from said first chamber for shifting said elements to their innermost positions within said casing and said valve by said inner piston element to a position closing said pressure fluid conveying means, a valve by-pass admitting initial amount of pressure fluid from said first to said second chamber, a pressure surface on said valve subjected to fluid at increased pressure from said second chamber for overcoming the opposed pressure of said inner piston element and shifting said valve an extent limited by the inner end of said outer piston element to partly open said pressure fluid conveying means, said valve pressure surface being responsive to fluid under still greater pressure from said second chamber for overcoming the opposed combined pressure'ofsaidpi ten elements and's'hift'ing said valve andelements a further extent to fully open -s'aid, -pressure fiuidjc enveying means. 7 Q o '7. In a device of the character described, a firstchamber having pressure fluid supplied therein and a second chamber, a casing between said chambers, inner and outer piston elements slidab le 'within said easing, a valve slidable within said casing,fpre'ssure fluid conveying means from said firstft o said second chambersgcontrolled by said'va-lve, actuating areas on said piston elementsconstantly subjected to pressure fluid from said first chamber for shifting and holding them to their innermost positions 7 Within said casing, said valve being shifted by one of said piston elements to a position closing said pressure fluid conveying means, a valve by=pass admitting initial amount of pressure fluid from said 'first' to said secondchambers, apre ssure surface on said valve subjected to fluid under increased pressure from said second chamber for over-,-

co'r'nin'g the opposed pressure of said one piston element and shifting said valve and one element an extent limited by the inner end of the other piston element to partly open said pressure fluid conveying means, said valve pressure 7 surface being responsiverto fluid under still greater pressure fronts-aid second chamber for overcoming the opposed combined pressure of said piston elements and shift ing said valve and elements a further extent to fully open said pressure fluid conveying means.

8. 'In a device of the character described, a first chamunder other conditions for limiting movement of said valve 7 in one direction, means uncontrolled by said'valve admit- I ting initial amount of pressure fluid from said 'first to said second chambers, a pressure surface on said valve subjected under certain conditions torfluid under-increased pressure from said second chamber for overcoming the opposed pressure of said one element and shifting'said valve and element an extent limited by theother element to partly open said pressure fluidco'nveying means, said valve pressure surface under other conditions being subjected to fluid under still greater pressure from said sec- 7 2 70nd chamber capable of overcoming the opposed combined pressure of said elements for shifting said valve and elements and further extend to fully open said pressure fluid conveying means. V

References Cited in the file of this patent UNITED STATES PATENTS 2,546,367 Majneri Mar. 27, 1951 Rawlings July 25, 1893' M 's: m I

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