US3097571A

US3097571A - Rotary fluid motor

Info

Publication number: US3097571A
Application number: US137711A
Authority: US
Inventors: Frank A Kaman
Original assignee: Thor Power Tool Co
Current assignee: Thor Power Tool Co
Priority date: 1961-09-05
Filing date: 1961-09-05
Publication date: 1963-07-16
Anticipated expiration: 1980-07-16

Description

July 16, 1 963 F. A. KAMAN ROTARY FLUID MOTOR .2 Sheets-Sheet 1 Filed Sept. 5, 1961 m a 9 an we ma mo mxm AM k a n d a m r. in M p United States Patent ware Filed Sept. 5, 1961, Ser. No. 137,711 Claims. (CI. 91-80) The present invention relates generally to fluid pressure actuated motors, and more particularly to portable tools having a rotary motor operated by means of fluid under pressure. The present invention is specifically concerned with the construction :of an improved pneumatic hand drill and with the improved method of assembling the rotary motor thereof.

The conventional rotary hand drill of the type under consideration has required precision methods of fabrication and assembly and, consequently, has been relatively difficult to manufacture and relatively expensive. Heretofore, it has been the general practice to machine the interior Wall surface of the housing for the rotary motor of the hand drill to precise dimensions so that the air cylinder or bushing of the rotary motor is mounted in the housing to form a fluid-tight engagement with a rotor eccentrically mounted therein. Since it is imperative for the eflicient operation of the rotary air motor to have a fluid sealing cont-act between the rotor and, the air cylinder at a point on the inner circumference of the cylinder, preferably adjacent the air intake port, great care must be taken to maintain these interengaging parts within predetermined dimensions and to assemble them in the desired precise relationship. The precision assembly of said parts has been a tedious and time consuming process which adds materially to the total cost of the tool.

More recently, certain attempted improvements have been made in the structure and method of assembly of the rotor and air cylinder to reduce the cost thereof, but the most advanced methods heretofore devised still required several manipulative steps and at least one of these improved methods necessitates permanently mounting the air cylinder with respect to the rotor so that the assembly cannot be readily disassembled for cleaning or repair.

Accordingly, it is an important object of the present invention to provide a fluid driven rotary motor which can be fabricated in a minimum number of operations and assembled in a more economical manner and thereby produced at a lower cost.

A further object of the present invention is to provide a less expensive rotary hand drill which is operable by means of fluid pressure.

It is also an object of the present invention to provide a rotary airpowered hand drill which can be easily and quickly assembled with the rotor element thereof in proper fluid-tight engagement with the air cylinder but which can be readily disassembled for cleaning and repair.

A still further object of the present invention is to provide an improved method of assembling a rotary motor of a pneumatic hand drill or similar airapowered tool.

Other objects of the present invention will be apparent from the detailed description and claim to follow when read in conjunction with the accomp'aning drawing wherein:

FIGURE 1 is a side elevational view of the rotary drill embodying the present invention;

FIGURE 2 is a fragmentary vertical longitudinal sectional view partially in side elevation of FIGURE 1;

FIGURE 3 is a fragmentary exploded vertical secfree tional view of the fluid motor of the rotary motor of the present invention;

FIGURE 4 is a transverse vertical sectional view along the line 4-4 of FIGURE 2; and

FIGURE 5 is a transverse vertical sectional View along the line 55 of FIGURE 2.

The compressed fluid powered rotary drill '10 shown in FIGURES 1 and 2 of the accompanying drawing is comprised generally of a housing section 15 adapted to support therein a pressure fluid motor 20 of the eccentrical wall chamber type, a compressed fluid control assembly 45), a drive gear assembly 80, and a conventional drill chuck assembly 90 operationally connected to said drive gear assembly.

As best shown in FIGURES l and 2, the housing section 15 has the general form of a pistol to provide convenient handling of the drill and has a depending generally cylindrical hollow hand grip section 22 and a hollow cylindrical fluid motor support section 23. The hand grip section 22 is provided with a compressed fluid passage 24 extending longitudinally thereof and an oil reservoir 26 communicating with the control assembly 4t The fluid pressure assembly 40 is disposed adjacent the upper end of the fluid passage 24 in the hand grip section 22 and normally prevents compressed fluid flowing therethrough. A suitable'coupling means 27 is provided in the lower wall of the hand grip section 22 for connecting a fluid supply line 25 with the passage 24. Also, a closure means 28 is provided at the lower end of the oilreservoir 26.

The fluid pressure control assembly 40 can be of any suitable design, such as a reciprocating finger control piece 42 extending transversely of and outwardly from the hand grip section 22 with an actuating fluid valve means 44 normally closing the fluid passage 24 as shown in FIGURE 2. A fluid supply passage 46 extends from the fluid valve means 44 upwardly to the fluid motor support section 23 through the end wall 29 thereof. A second valve means 47 is mounted in the hand grip section 22 above the control assembly 40 to close the passage 46 at a point between the valve means 44 and the support section 23.

The cylindrical rotor and gearing support section 23 of the housing extends forwardly from the hand grip section22 and is closed at its right orrear end by an end wall 29 with a generally cylindrical lateral wall 30 extending forwardly therefrom to provide an elongated hollow cyindrical opening section 31. The housing section 15 has a second cylindrical section 35 of a somewhat larger internal diameter which extends longitudinally forwardly from the end of the section 31 and is adapted to receive therein the drive gear assembly of the rotary motor 20. The axial opening 38 at the outer end thereof is adapted to be closed by a case gear or locking nut 39 threadably engaged in the cylindrical section 35. The pressure rotary motor 24 with the associated drive gear assembly 80 are adapted to be inserted into the housing section 15 through the axial opening 38 and are held operatively in position within the housing section 15 by the case gear 39.

The rear end wall 29 of the housing section 23 has formed therein a cylindrical recess 36 which is eccentrically disposed with respect to the longitudinal axis of the cylinder section 31. A hearing 37 is disposed in said recess 36 for rotatably supporting the pinion or drive shaft 52 of a rotor member 54 of the fluid motor 20'. An anchor pin 33 is also fixedly mounted in the end wall 29 adjacent the cylindrical lateral wall 30 and extending out wardly from said end wall 29 a short distance into the interior of the cylindrical section 31. A narrow rectangular slot 88 which is cut in the lower inner lateral surface of the lateral wall 30 extends the length of the cylindrical section 31 and is adapted to receive therein a wavy leaf spring element 34.

The pressure fluid rotary motor 20 is comprised of the elongated pinion or drive shaft 52 which has fixedly mounted thereon intermediate the ends thereof the rotor member 54 provided with a plurality of centrifugally reciprocable vane members 56 mounted in slots 57 disposed at circumferentially spaced points about the periphery thereof for movement outwardly and inwardly relatively to the periphery of the rotor upon rapid rotation of the rotor.

A cylindrical sleeve member or motor cylinder 55 open at both ends and having an outside diameter less than the interior diameter of the cylindrical section 31 is freely slidable therein and is eccentrically disposed about the rotor member 54. As in the conventional rotary motor, the vane members 56 form a slidable and scalable contact with the inner surface of the cylinder member 55.

The cylinder member 55 can be formed of an inexpensive standard piece of steel tubing, such as seamless cold drawn steel tubing, which is cut to the desired length with the opposite ends 60, 61 being machined square so that the respective faces thereof are parallel. The lateral surfaces of the tubing require no further machining or finishing and, as explained hereinafter, need not have precisely mating surfaces with the material surfaces of the housing section 31.

A rear end plate 65 is disposed within the housing section for sealably engaging the rear end 60 of the air cylinder 55 and provides a lateral bearing surface against which the side of the vanes 56 and rotor 54 make a slidable sealing contact. The end plate 65 has a small eccentrically disposed passage 62 therein through which the rear end of the drive shaft 52 extends. The end plate 65 also has an aperture 63 spaced from the said passage 62 into which the pin 33 extends to hold the plate 65 against rotation. The end plate 65 is further provided with an arcuate shaped pressure fluid inlet port 64 and a cylindrical passage 64a disposed radially inwardly of said port 64. The port 64 and passage 64a are connected by a groove 64b in the forward or inner surface thereof. The ports 64 and 64a which assist in moving the vanes 56 outwardly when starting the rotor 54 are adapted to communicate with the fluid supply passage 46 to convey fluid under pressure into the interior of the rotary motor The opposite or forward end 61 of the motor cylinder 55 is sealably closed by a front end plate 66 which abuts the adjacent end 61 of the cylinder 55, but is spaced from the shoulder 67 formed at the end of the cylindrical lateral wall 30. The plate 66 is secured against rotation by an anchoring means or slot 68 therein which coacts with a pin means 68a mounted in the housing 15. The front end plate 66 also has an axial passage 69 extending therethrough to accommodate the forwardly extending portion of the motor drive shaft 52.

A pressurized fluid outlet port 70 of arcuate shape also extends through the plate 66 and is spaced radially from the axial passage 69 to permit the compressed fluid to escape from the interior of the cylinder 55 and pass to the surrounding atmosphere through openings 72 in the wall of the forward cylindrical section 35'. The outlet port 70 of the forward end plate 66 and the fluid inlet port 64 of the rear end plate 65 are disposed out of alignment in different circumferential positions as shown in FIG. 5. The circumferential spacing of these ports is so related with the spacing of the rotor vanes 56 as to permit complete exhaustion of the motor fluid and prevent back pressure within the motor 20.

As previously mentioned, it is essential that the rotor 54 form a sealable engagement with the motor cylinder 55 at a point on the inner surface thereof between the fluid inlet 64 and the outlet port '70, preferably adjacent but circumferentially spaced from the fluid inlet opening 46 in order to have the rotary fluid motor 20 operate efficiently. In the present invention, the parts are accurately positioned to achieve the necessary sealing engagement between the rotor 54 and the cylinder 55 in a most inexpensive and eifective manner by positioning the flat spring element 34- in the rectangular slot so that it exerts a continuous and even pressure on the outer lateral surface of the cylinder 55 at spaced points longitudinally therealong so that the cylinder 55 during the assembly operation is urged upwardly to properly position said cylinder 55 in sealing engagement with the periphery of the rotor 54. Since the peripheral surface of the rotor 54 is fixedly positioned with respect to the cylindrical wall section 30, the spring element 34 presses the cylinder 55 against the surface of the rotor 54 with sufficient force to effect the required sealing engagement, but without exerting undue pressure which would tend to appreciably retard the rotation of the rotor 54 about its longitudinal axis.

In the forms shown, the spring element 34 is made from flat clock spring stock having a length of 1% inches, a width of A inch, and a thickness of .008 inch. The spring element 34 has a double wave-like form with the crests of the waves being spaced about inch and each of the waves having an amplitude of & inch. When compressed to inch, a weight of 4-5 pounds is required.

In order to utilize the power of the pressure fluid motor 16, the pinion or rotor drive shaft 52 to which the rotor 54 is fixedly mounted for operatively driving the gear assembly extends forwardly and is rotatably journaled in a forward bearing 74 supported by a center plate member 160 mounted within the cylindrical section 35. A suitable speed reducing drive gear assembly 80 comprised of idler gears, idler pins, bearings and an internal gear of conventional design and arrangement in operatively connected with the drive shaft 52 for transmission of rotary power from the air motor to the spindle 90. The spindle is rotatably mounted in the case gear 39 which also serves as the locking means for holding the rotary motor 20 and drive gear assembly 80 and all their component parts in properly operating relationship within the housing section 15. The spindle 90 extends outwardly from the case gear 39 and has a suitable gear chuck secured thereto. The gear chuck 95 can be of any conventional design for securing a drill bit or other work thereto.

The manner of assembling the working parts of the drill and the order in which the several working parts are mounted within the housing 15 will be readily apparent to those skilled in the art from the detailed vertical sectional view shown in FIGURE 2 of the drawing and particularly from the fragmentary exploded view thereof shown in FIGURE 3 of the drawing, when taken in conjunction with the foregoing detailed description. Thus, the pressure fluid operated rotary motor 20 of the present invention can be readily assembled by performing the following general sequence of steps: first, the rear end bearing 37 and the rear end plate 65 are placed in abutting contact with the rear end wall 29 of the housing section 15. The rotor 54 with its drive shaft 52 supported in the rear end bearing 37 is eccentrically mounted within the cylindrical opening 31 in the housing section 15. The motor cylinder 55 is then inserted into the cylindrical opening 31 surrounding the rotor 54 with the rear end surface contacting the end plate 65. A spring element 34 is next inserted into the groove or slot 88 in the housing section 15 to contact the outer surface of the cylinder 55 to properly position said cylinder in sealing engagement with the periphery of said rotor 54. If desired, the spring element 34 can be inserted in the slot 88 before inserting the motor cylinder 55 into the housing section 15. The front end plate 66 is then placed in abutting contact with the front edge of the rotor 54 with the drive shaft 52 extending through the plate 66. The

front drive shaft bearing 74 including the center plate 100 and the gear assembly 80, are next arranged to operatively engage the drive shaft 52 which in turn transmits power to the spindle 90 and a cylindrical defector 110 is mounted on the outer wall of section 35. A case gear or locking nut 39 is then placed over the end of the gear assembly 80 and the spindle 90 and axial pressure is applied to force the several parts into operative engagement within the housing section 15. By threadably mounting the case gear 39 in the threaded section of the axial open-ing 38 in the housing section 15, the desired degree of axial pressure can be readily applied. The case gear 39 thus serves to lock the several parts in operative position within the housing section and completes the assembly operation.

During the assembling procedure and before the case gear 39 is threadably tightened and thereby draws the several parts into their operative positions, the spring element 34 resiliently urges the motor cylinder 55 radially within the cylindrical opening 31 to position the cylinder 55 in fluid sealing engagement with the rotor 54. After the gears, bearings, and other accessory elements of the fluid motor have been mounted on the drive shaft of the motor, the several parts, including the motor cylinder 55, are tightly drawn into alignment and locked in operative position by the application of axial pressure exerted by the gear case 39 threadably engaging in the housing section 15. Thereafter, reliance is no longer made on the spring element 34 to hold the motor cylinder 55 in sealing engagement with the rotor 54.

It will be apparent from the foregoing description that the rotor 54 and the motor cylinder 55 are brought into sealing engagement during the assembly operation without requiring accurate machining and dimensioning of the housing 15, without machining the lateral surface of the motor cylinder 55 or accurately dimensioning the cylinder 55 with respect to the housing 15, and without fixedly securing the motor cylinder 55 with respect to the housing 15 or with respect to any of the other parts of the motor assembly. Also, by having the motor cylinder 55 loosely mounted within the housing section 15, it is possible to readily assemble the rotary motor 20 without requiring any accurate manual positioning of the parts during the assembly procedure, thereby very substantially reducing the cost of assembling.

I claim:

1. In a pressure fluid operated rotary motor including a housing section having a rotor mounted eccentrically within a motor cylinder member in said housing and having circumferentially spaced compressed fluid inlet and outlet passage communicating with interior oi said motor cylinder, said inlet passage having a source of pressure fluid connected thereto, and said rotor having means associated therewith for operatively driving a work piece, the improvement comprising: a generally cylindrical opening formed in said housing section, a pressure fluid motor cylinder disposed in said cylindrical opening, said motor cylinder having an outer diameter less than the inner diameter of said cylindrical opening, a rotor member eccentrically mounted within said motor cylinder and having a plurality of circumferentially spaced vanes adapted to form a continuous engagement with the inner surface of said motor cylinder when the said rotor is rotated rapidly, and spring means engaging said motor cylinder to position said motor cylinder in a fluid sealing and sliding engagement with the periphery of said rotor.

2. In a pressure fluid operated rotary motor including a housing section having a rotor mounted eccentrically within a motor cylinder member in said housing and having circumferentially spaced compressed fluid inlet and outlet passage communicating with interior of said motor cylinder, said inlet passage having a source of pressure fluid connected thereto, and said rotor having means associated therewith for operatively driving a work piece, the improvement comprising: a generally cylindrical opening formed in said housing section, a pressure fluid motor cylinder disposed in said cylindrical opening, said motor cylinder having an outer diameter less than the inner diameter of said cylindrical opening and adapted for radial movement therein, a rotor mem- 'ber eccentrically mounted within said motor cylinder which has a plurality of circumferentially spaced vanes adapted to form a continuous engagement with the inner surface of said motor cylinder when the said rotor is rotated rapidly, and spring means engaging the outer lateral surface of said motor cylinder at longitudinally spaced points therealong to position said motor cylinder in a fluid sealing and sliding engagement with the periphery of said rotor between said cincumferentially spaced fluid inlet and outlet passages.

3. A pressure fluid operated rotory motor as in claim 2 wherein the spring means comprises a flat spring seated in a groove in the housing section with a portion of said spring projecting into said cylindrical opening and engaging the outer surface of said motor cylinder to position said motor cylinder in a fluid sealing slidable engagement with the periphery of said rotor.

4. A portable pressure fluid actuated tool comprising in combination housing means enclosing a pressure fluid actuated rotary motor including a motor cylinder having a smooth inner surface and an eccentrically mounted rotor having a plurality of spaced vanes disposed for movement outwardly and inwardly relative to the periphery of the rotor for engagement with said inner surface upon rapid rotation of said rotor, said motor cylinder having an exterior diameter less than the inner diameter of the cylindrical housing section, spring means engaging said motor cylinder and positioning said cylinder in a fluid sealing and relatively slidable engagement with said rotor, and mechanical means applying axial pressure to opposite ends of said motor cylinder and rotor to retain said cylinder and rotor in said fluid seal ing and relatively slidable engagement.

5. A portable pressure fluid actuated tool comprising in combination housing means enclosing a pressure fluid actuated rotary motor including a motor cylinder havmg a smooth inner surface and an eccentrically mounted rotor having a plurality of spaced vanes disposed for movement outwardly and inwardly relative to the periphery of the rotor for engagement with said inner surface upon rapid rotation of said rotor, said motor cylinder having an exterior diameter less than the inner diameter of the cylindrical housing section, said housing having spaced end plates mounted therein which are restrained against rotary movement, one of said plates forming a sliding sealing engagement with one end of said rotor and motor cylinder and the other said plate forming a sliding sealing engagement with the other end of said rotor and motor cylinder, said one plate having an arcuate passage extending therethrough adapted to admit pressure fluid into the interior of said motor cylinder and said other plate having a second arcuate passage therethrough spaced circumferentially from said first arcuate passage which is adapted to conveying pressure fluid outwardly from said motor cylinder, spring means engaging said motor cylinder at spaced points positioning said cylinder in a fluid sealing engagement with said rotor between said pressure fluid passages, and mechani cal means associated with said housing which applies axial pressure to said plates to secure said cylinder in fluid sealing engagement with said rotor.

References Cited in the file of this patent UNITED STATES PATENTS 690.79 8 Van Anken I an. 7, 1902 758,122 Waters Apr. 26, 1904 1,048,453 Hobt Dec. 24, 1912 1,339,565 Lambert May 11, 1920 2,830,560 Doeden Apr. 15, 1958

Claims

1. IN A PRESSURE FLUID OPERATED ROTARY MOTOR INCLUDING A HOUSING SECTION HAVING A ROTOR MOUNTED ECCENTRICALLY WITHIN A MOTOR CYLINDER MEMBER IN SAID HOUSING AND HAVING CIRCUMFERENTIALLY SPACED COMPRESSED FLUID INLET AND OUTLET PASSAGE COMMUNICATING WITH INTERIOR OF SAID MOTOR CYLINDER, SAID INLET PASSAGE HAVING A SOURCE OF PRESSURE FLUID CONNECTED THERETO, AND SAID ROTOR HAVING MEANS ASSOCIATED THEREWITH FOR OPERATIVELY DRIVING A WORK PIECE, THE IMPROVEMENT COMPRISING: A GENERALLY CYLINDRICAL OPENING FORMED IN SAID HOUSING SECTION, A PRESSURE FLUID MOTOR CYLINDER DISPOSED IN SAID CYLINDRICAL OPENING, SAID MOTOR CYLINDER HAVING AN OUTER DIAMETER LESS THAN THE INNER DIAMETER OF SAID CYLINDRICAL OPENING, A ROTOR MEMBER ECCENTRICALLY MOUNTED WITHIN SAID MOTOR CYLINDER AND HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED VANES ADAPTED TO FORM A CONTINUOUS ENGAGEMENT WITH THE INNER SURFACE OF SAID MOTOR CYLINDER WHEN THE SAID ROTOR IS ROTATED RAPIDLY, AND SPRING MEANS ENGAGING SAID MOTOR CYLINDER TO POSITION SAID MOTOR CYLINDER IN A FLUID SEALING AND SLIDING ENGAGEMENT WITH THE PERIPHERY OF SAID ROTOR.