US2402972A - Centrifugal governor for tools - Google Patents

Description

JulyZ, w46. w. G. MITCHELL CENTRIFUGAL GOVERNOR FOR TOOLS Filed Nov. 20, 1944 INVENTOR. Muff ,4f/mmf.

Patented July 2, 1946 2,402,972 CENTRIFUGAL GOVERNOR FOR TOLS Walter G. Mitchell, Aurora, Ill., assigner to Independent Pneumatic Tool Company, Chicago, Ill., a corporation of Delaware Application November I20, 19414, Serial No. 564,339

4 Claims. l

This invention relates to portable pneumatic tools ofV the rotor operated type and more particularly to an improved governor device therefor.

Among the objects of my invention are the following:

To provide a centrifugally operated governor device, all parts of which are assembled exterior of the tool as a complete, self-contained, unitary xture, handled, and insertible and removable as such with respect to the tool to which it is applicable;

To provide a governor device which is simple in construction and easy to manufacture and install in a tool;

To provide a governor device with a valve arrangement controlled thereby and which valve mechanism is a part of the unitary character of iixture and is in axial alinement with the tool rotor with which the governor device is directly connected for rotation thereby;

To provide a governor device in which the outlet ports controlled by the valve mechanism open laterally thereof into a tool 'chamber extending about the governor device to eliminate the necessity of matching or accurately locating ports in several positions in the tool casing for directing the motive uid from the governor valve to the tool rotor;

To provide a governor device having a revoluble body member having the uid passage ports therein and a valve member slidably mounted on the body member for opening and closing said ports and centrifugally responsive elements interposed between and operable on opposed, angularly disposed surfaces on said body and valve members for moving the valve member axially of the body member to close said ports and means normally urging the valve member in the opposite direction to open said ports; and

To provide the specific governor and valve device herein shown, described and claimed.

Inthe accompanying drawing illustrating said specic embodiment of my invention- Fig. 1 is a fragmentary side elevational view, partly in longitudinal section, of a portable pneumatic tool equipped with a combined governor and valve device of my invention, the governor and valve device being shown in section taken on line i-i of Fig. 2;

Fig. 2 is a bottom plan view of the governor device removed from the tool;

Fig. 3 is a longitudinal rsectional view of the governor device taken on line 3--3 of Fig. 2;

Fig. 4 is a transverse sectional view taken on line iiie of Fig. 3:

Fig. 5 is a view of the screw-plug and spring assembly of the governor device to be later de-V scribed;

Fig. 6 is a fragmentary, longitudinal sectional view of a modied form of construction to be later described; and

. 2 Fig.\'7 is a side elevational view of the structure shown in Fig. 6. i

The governor device of my invention comprises an assembly of parts which when in assembled relation, as shown in Fig. 3, provides'a self-contained, unitary governor xture handled and insertible and removable as such with respect to the tool in which the governor device'is used. Among the parts constituting the governor assembly is a body member i generally circular in form and having an intermediate, radially extending, table portion 2 from the opposite sides of which extend cylindrical portions 3, t of less diameter as shown in Figs. 1 and 3. The cylindrical portions 3, d are alined axially of the body member l as shown. l

The second partof the governor device is a valve member 5 slidably mounted by its sleeve portion 6 on the cylindrical portion 3 of the body member l. Said valve member 5 has at the base of said sleeve 6 a canopy portion 'l opposed to the table portion 2 and angularly disposed with respect thereto. The canopy portion 'l has a marginal flange 8 slightly beyond and out of the path of the outer edge of the table portion 2 to retain the ball-like centrifugally responsive elements 9, 9 between the table and canopy portions 2 and 7 as shown in Figs. 1 and 3.

The ball-like elements 9 seat against the table portion 2 in radial, guide ways l0, i0 therein, one for each ball element. In the specific embodiment of my invention shown herein and as detailed in Fig. 4, the ways i0 are four in number and are equally spaced, circumferentially, about the axis of the'body member I. The bottom surfaces ll, l! of the ways I0 are substantially straight and normal to the governor axis, while downward inclination to the ways. The freely movable ball elements 9 in their outward movement along the ways lo in response to a centrifugal force on rotation of the body member i at a given speed will lift the valve member 5 upwardly, axially of the body member I to close uid passage ports I2, l2 with which the body member i is provided for the valve sleeve 3. The ball elements 9 act against the angularly opposed surfaces of the table and canopy portions 2 and l and lift the sleeve G as just described. The ways i@ are deep enough to retain the ball elements S Vagainst circumferential displacement of the body sleeve 6, and have movement therewith in the operation of the device. Said pin holds the valve member 5 from rotation on the body member I, but coacting with the sides of the slots I1 guides the valve member 5 in its sliding movements.

The slots I1 are elongated suinciently axially oi the body member I to limit the valve member 5 in its sliding movement to positions fully opening and fully closing the ports I2, respectively, the pin contacting ends of the slots I1 at said respective positions. At the lower limit of its sliding action, as shown in Figs. 1 and 3, the valve member 5 opens the ports I2, while at the upper limit of its sliding action the valve member 5 closes the ports I2 as will be apparent from the showing in Figs. 1 and 3. The ports I2 connect with an inlet passage I8 in the upper end of the body member I and through which compressed air or other motive iiuid is supplied to the tool motor to which the governor device is connted and rotated. The valve member 5 through its sleeve 6 controls the amount of compressed air furnished to the tool motor for regulating its rotative speed in respect to the load thereon.

The spring I3 has its lower looped end I9 engaged with an anchor member in the form of a non-circular clock 20 extending cross-wise of the bore I4 and fitting in a similarly shaped slot 2l provided in the lower end of the body member I. Said slot 2l intersects the bore I4 as shown in Fig. 2 and the block 2 is normally seated therein against its bottom surface 22 by the spring I3; The slot 2| holds the block from accidental rotation with respect to the spring I3 and the body member I.

Screwed into a tapped opening in the block 20 is a screw-plug or equivalent member 23 to which the lower looped end I9 of the spring I3 is connected as shown in Fig. 5. As there shown, the connection mentioned includes an aperture and slot arrangement in the screw-plug 23 to locate the connection within the bore I4 of the body member I. The spring I3 by its tension normally holds the valve member 5 against the ball elements -8 and urges the valve member downwardly to a port opening position. The cam action which the canopy 1 provides on the ball elements 9 moves the latter inwardly of the ways i as the centrifugal force decreases under a load on the tool motor and the valve member descends to open the ports |21 to increase the supply of compressed air to the tool motor as required by the load condition in a drilling or otherwork The tension of the spring I8 is adjusted by manually pulling the' block 2G out of the slot 2l and turning the block in the required direction relatively to the screw-plug 23. 'Ihis results in screwing the plug 23 inwardly or outwardly with respect to the block 2a and increases or lessens the spring tension. .When the desired tension is obtained the block is located in the rotative position necessary to re-enter the slot 2|, the spring I3 reseatng the block in the slot. It will be noted that the block in its seated position extends beyond the lower end of the body member I for the keying` DurpOse to be presently described and to make the block available for grasping for spring tension adjustment.

With the governor device in unitary form as f' with an air supply hose (not shown).

- 4 The importance of this is that the governor device can be calibrated for a predetermined speed outside the tool and thereby eliminate the necessity of building up a complete machine without the precise knowledge as to the Adegree of governor control which will be achievable.

The tool in which the governor device herein shown, and described is inserted has an outer casing 24 having a side or other handle 25 provided with a main supply passage (not shown) for the compressed air as in tools of the character to which my improved governor device is applicable. The handle member 25 has at its outer end a nipple iitting'ZB for the connection The main supply passage in the handle 25 is connected through a throttle valve (not shown) in the handle to a passage 21 in the tool casing 24 and this passage 21 leads to a chamber 28 in the upper end of the tool case above the governor device when located therein as shown in Fig. 1.

At this point, the case 24 has a wall portion 29 which divides the chamber 28 from a further chamber 30 which surrounds the inserted govrotor assembly of the tool. The lower cylindrical,

portion 4 of the governor device has bearing in an opening 38 in the disc member 33 and said portion 4 is connected to the rotor 40 of the tool by the key block 20 which extends into a key slot 31 in the upper trunnion portion 38 of said rotor 40. 'I'he latter supports the governor in place and has radial slots or recesses 4Ito mount the operative blades 42 of the rotor as in mechanisms of this character.

The blades 42 work against the inner surface of the rotor cylinder 43 dowelled within the tool case 24 and having a plurality of inlet ports 44, 44 serving the blades 42 on their high pressure sides as'in motor devices of this design. The inlet ports 44 lead from a supply `passage 45 in the rotor cylinder 43 and said passage 45 connects with a supply passage 46 in the tool case, the latter passage opening into the chamber 3U in dvvihici the governor device is located as shown in The ports l2 of the governor device are arranged about the governor axis, which s in alinement with the rotor axis, and all of the ports I2 open directly into the chamber 3U, thus avoiding the necessity of matching and accurately locating herein before mentioned and the block 20 acceswhile the governor xture is exterior of the tool.

ports in the two devices, the governor device and the tool case as apparent. The passage d5 in the rotor cylinder H3 connects with the tool case passage 48 through a port i1 in the upper end plate 35 of the rotor assembly. In the arrangement shown, the passage d6 leads from the chamber 36 directly to the rotor supply passage 45, thereby simplifying the fluid pressure supply system of the tool.

As shown in Figs. 1 and 3, theupper end portion 3l of the body member I of the governor device is provided with the fluid flow passage I8 for the ports I2 and this pressure opens through the upper end of the body member I directly into the chamber 28 to receive the pressure fluid sup- .I

ply therefrom. This passage I8 is closed below the ports I2 by a cross-wall 48 with which the body member I is provided to close'the ports I2 from the bore Il in which the springdevice I3 is located. The body portion I has an external seat B9 to provide a stop for the governor` delvice when inserting it into the chamber 3l) and to close chamber 28 to chamber 30except through ports l2. The governor device is inserted into the tool case through the lower open end thereof before the rotor parts are applied in assembling the'tool. The governor device is removed from the tool case in a reverse operation.

In operation of the tool and governor mech# anism herein disclosed, compressed air enters the upper end portion 3| of the governor device Ifrom the chamber 28 when the throttle valve in the tool handle is opened, an operating trigger block 50 "passage ports therein,

mounted on the body member for opening and l closing said ports, said members having opposed being mounted in the handle to open the throttle valve, as indicated in Fig. 1. When the rotor 40 is not in rotation, the valve member 5 of the governor device is its lower position fully opening the valve ports I2 .and the rotor is supplied' with a driving motivev fluid to rotate .,it. As the rotor speeds up the centrifugally responsive mechanism of the governor device functions to y whereupon the valve member v5 is moved down-v wardly by the spring I3 and the air volume to the rotor is increased as required by the load thereon.-

The governor action is automatic, as is apparent, and the operation of the rotor t0 is under the control of the governor through its unitary valve device in accordance ywith the loads impressed thereon.

The air exhausts from the rotor cylinder d3 through exhaust ports therein, an exhaust passage 5I in the tool case 24 being shown in Fig. l. In the modified form of structure shown in Figs. 6 and '7, the-cross-pin I8a for the slidable valve member 5a mounts rollers 52, 52 in the slots I'la, 11a in the body member la of the governor device. The rollers 52 -on the cross-pin 16a. provide for easier movement of the pin in said slots with the valve member 5a. The slots Ha have the backwall formation as shown in the drawing to prevent displacement of the rollers from the slots, the valve member keeping the roller therein. Th'e rest of the, structure shown in Figs. 6 and?- conforms to that shown inthe other figures except that the cross-wall in the body member Ia between the ports and the slots hasl an air deiiector S3 for the air iiow towards the ports.

The number of centrifugally responsive ball elements employed in the governor device of my invention will depend upon th'e speedcharacteristics to be controlled. In some cases three of such elements will be adequate, while in other cases a greaternumber will be required. Moreover,v the relative angle between the table and canopy portions in conjunction with the spring tension to secure the most satisfactory results with particular ball sizes available is used;

The details of construction and arrangement of parts shown and described may be variously changed and modified without departing from the spirit and scope of -my invention, except as pointed outintheannexedclaims. Y

I claim. as my invention: 1. Aovernor device of the character described comprising, a revoluble body member having iluid a valve member slidably angularly 4disposed surfaces, centrifugally re- -sponsive elements interposed between said sur faces and acting *thereon for moving the valve member axially of the body member to close said ports, spring means normally urging the valve member in the opposite direction to open said ports, and means for adjusting the tension of said spring and serving as a, connector for the `body member with means which rotates it.

2. A governor device of the character described comprising, a revoluble body member havingfluid passage ports and a bore therein, a valve member slidably mounted on the body member for opening and closing said ports, said members having opposed angularly4 disposed surfaces,v centrifugally responsive elements vinterposed between said surfaces and acting thereonV for moving the valve4 member axially of the body member to close said ports, spring'means located within the bore of the body member and connected with said valve member for normally urging the same in a direction to open said ports, and means available at one end of the bore for adjusting the ltension ,ofv

said springmeans and serving as a connector. for the body member with the means which rotates it.- l,

3. `A governor device of the character described comprising, a revoluble -b'oly member, an externa! member mounted on the body member, a

cross-pin slidably, lbut nom-rotatably connectingthe external member to the body member by having its ends extending into slots inthe body member, rollers mounting the ends of the pin within said slots, and ,means for moving the external member along the rbody member compris ing mechanical means for moving the external 'member along the body member in one direction and centrifugal responisive means for moving the external member along the body member in the opposite direction.

4. A combined governor and valve device in the form of a unitary 'fixture for pneumatic toolsv comprising, a one piece, revoluble, body member having cylindrical bearing portions at its opposite ends to rotatably support the body member in the tool casing, said body member having a bore and a pressure fluid passage therein, both extending axially of the body member with the bore opening through one end of the bodymember and the passage opening through the opposite end. of the body member, said body member having an integral wall portion dividing the passage from the bore and the body member having laterally opening ports for the outflow of pressure iiuid from said passage adjacent to said dividing wall, a valve member in the form of a sleeve l slidably mounted on the body member for opening and closing said ports, said body and sleevel membershaving laterally extending table and canopy portions having opposed, angularly disposed, surfaces, centrifugally responsive bali-like elements interposed between said surfaces and acting thereon for moving the valve member*- axially of the body member to close said ports,

and spring means located within said bore andv connected at one end with the valve memberadjacent to said dividing wall and at the other end with said body member adjacent tothe outer end ofthe bore for normally urging the valve member in a direction toopen said ports.

WALTER G. MITCHELL.

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