US3529498A - Power wrench - Google Patents

Description

Sept. 22, 1970 o. v. NORTHCUTT POWER WRENCH Original Filed 001:; 24, 1965 FIG.*3

FIG.2 53

'INVENTOR OREN V. NORTHCUTT WWW ATTORNEY United States Patent 3,529,498 POWER WRENCH Oren V. Northcutt, Dallas, Tex., assignor of one-half t James E. Northcutt, Dallas, Tex. Continuation of application Ser. No. 684,556, Nov. 20, 1967, which is a continuation of application Ser. No. 504,670, Oct. 24, 1965. This application Feb. 5, 1969, Ser. No. 800,340

Int. Cl. B25b 21/00 US. C]. 81-54 13 Claims ABSTRACT OF THE DISCLOSURE A wrench including a shaft rotatable by a motor and having a stud at one end thereof parallel but eccentrically disposed with respect to the longitudinal axis of the shaft. A ball is carried by a ratchet head and has an opening eccentric with respect to a diameter of the ball into which the stud rotatably projects. Rotation of the shaft causes oscillation of the ratchet head with a force and stroke dependent upon the load imposed on the ratchet head by a driven wrench member. A resistive force may be provided on the driven wrench member in order to permit ratchet action to occur even when the wrench drive does not carry a substantial load. The direction of the ratchet action may be selectively changed without changing the direction of rotation of the motor.

This application is a continuation of application Ser. No. 684,556, filed Nov. 20, 1967 which was a continuation of Ser. No. 504,670, filed Oct. 24, 1965; both now abandoned.

The present invention relates to power wrenches.

Power wrenches are frequently used. For example, pneumatic wrenches of the general type shown in US. Pat. 2,263,736, are used to remove studs from engine heads and to remove nuts in a variety of locations. The construction of this type wrench is such, however, that a rather cumbersome structure is disposed coaxially outwardly from the stud or nut being manipulated. In many cases head room is not available to permit such a wrench to operate. Accordingly, effort has been made to provide a wrench requiring little head room. Exemplary of such a wrench is that shown in US. Pats. 2,264,012; 2,086,261; and 2,758,569. While certain of the prior art structures have met with a degree of success, the structures are generally complex, rather large, and sometimes unreliable in operation.

An object of the present invention is to provide an efficient, compact, and comparatively simple power wrench of the type that may be driven in a desired direction to remove or set a stud, bolt, or the like.

A further object is to provide such a wrench that may be used in a variety of applications, including the driving of sockets.

Another object is to provide such a wrench that works rapidly when the load is light, yet which is self-regulating to increase the torque delivered, at reduced speed, when the load becomes heavy.

Yet a further object is to provide a power driven ratchet wrench which will ratchet properly even under conditions where no material external load is being handled by the wrench.

The present invention provides a power wrench which comprises a rotatable shaft, motor means for rotating the shaft, an oscillatory head, a frame for pivotally carrying the head, means for interconecting the shaft and ratchet head to oscillate the head when the shaft is rotated, a rotatable wrench drive, and means operably interconnecting the oscillatory head and wrench drive to cause ice the wrench drive to rotate in one direction while the oscillatory head oscillates.

In a preferred embodiment, the axis of rotation of the motor driven shaft is perpendicular to the axis of rotation of the wrench drive. Moreover, in the preferred embodiment the means for interconnecting the shaft and ratchet head include a stud, parallel but eccentrically disposed with respect to the axis of rotation of the shaft, and a ball having an opening into which the stud projects. Preferably the opening in the ball is eccentric with respect to the balls diameter. The ball is carried within an arcuate slot, formed in the oscillatory head.

A preferred embodiment further provides a plurality of teeth on the oscillatory head and a pawl which is carried by the wrench drive. The pawl and teeth are so disposed that the pawl engages the teeth during the movement of the teeth in one direction, but is disengaged from them during their movement in the opposite direction.

Yet aanother provision of a preferred embodiment is means for placing a resistive force on the wrench drive means during the ratchet stroke. This premits ratchet action to occur even when the wrench drive means carries no substantial load.

For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a power wrench in accordance with the present invention;

FIG. 2 is a fragmentary partially sectioned side view of the wrench of FIG. 1,

FIG. 3 is a fragmentary end view of the structure of FIG. 1, with the ratchet head 25 removed and the ears 23a and 23b sectioned for clarity;

FIG. 4 is an end view of the crank shaft 31, with the ball means 37 assembled thereon in the position of maximum stroke; and

FIG. 5 is a view of the structure shown in FIG. 4, but with the ball means 37 rotated into the position of minimum stroke.

Referring now to FIG. 1, therein is illustrated generally at 11 a power wrench in accordance with the present invention.

The wrench 11 may be powered by a variety of means. However, an air motor 13 is employed in the embodiment illustrated. To the motor 13 is connected an air hose 15 through the conduit handle 16. An air control valve carried in the conduit-handle 16, is positioned by thumb button 17 to admit air to the motor when it is desired that it be actuated. The motor 13 of the rotary type having a plurality of vanelike members driven by air.

If desired, an electric motor may be substituted for the air motor 13. Since essentially any rotary type motor means may be utilized, and since a host of suitable conventional motors are available, no specific motor detail is illustrated herein.

A lower annular casing 21 extends from the lower portions of the casing of motor 13. On its extremity it carries a yoke 23. The yoke 23 comprises spaced apart ear portions 23a and 23b. Ear 23a has formed in it a large circular opening. Moreover, ear 23b carries a circular opening, the center of which is aligned with the center of the opening in ear 23a. The opening in ear 23b is considerably smaller than in ear 23a.

Ratchet head 25 is carried between the ears 23a and 23b of yoke 23.

A large circular opening is formed through the central portion of ratchet head 25 (see FIG. 2) and a plurality of teeth 27 are disposed about the entire periphery of the opening.

A shaft 31 is carried within the annular casing 21. An annular bearing 33 toward the lower end of the shaft (as viewed in FIG. 2) is provided for supporting the shaft. Preferably an upper bearing of similar construction (not illustrated) is also provided. The shaft 31 has its driven end connected to the rotating mechanism of motor 13.

The end of shaft 31 remote from the motor 13 is pro vided with a cylindrical projection or stud 35. The longitudinal axis of this cylindrical projection is parallel to, but displaced from, the axis of the shaft 31.

The projection 35 extends into a mating opening which is formed in a ball member 37. The axis of this mating opening is preferably offset from the axis of the ball, i.e., it is not concentric with a diameter of the ball. The structure and its effect will be discussed at a later point hereinafter.

The ball 37 is carried within a suitable arcuate slot 39 which is formed in the upper regions of the ratchet head 25. The ball 37 may be moved sideways in the arcuate slot 39; however it is retained in position with respect to movement along any other axis because of the conformance of the surface defining the recess with the shape of the ball. Accordingly, movement of the ball in a side-toside direction, as seen in FIG. 2, necessarily carries the ratchet head 25 along with it. Since the ratchet head 25 is constrained to rotate about an axis passing through the openings in ears 23a and 23b, the ratchet head will rock back-'and-forth as the ball 37 is moved about by rotation of crank 31. It should be appreciated that the thickness of the ratchet head 25 is sufficiently greater than the diameter of the ball 37 to permit movement of the ball in a direction transverse to the plane of the rocking movement. Thus on rotation of this shaft, the ball member 37 is able to ride back-and-forth within the arcuate slot 39 without striking the sides of the ears 23a and 23b.

A wrench drive assembly 41 is carried within the toothsurrounded circular recessed central portion of ratchet head 25. The drive assembly 41 has an enlarged generally cylindrical mid-portion 43' which is disposed between the ears 23a and 23b of the yoke 23 (see FIG. 3). This cylindrical enlarged portion is slotted or recessed along a side or peripheral portion in such a way that spaced apart shoulders 45 and 46 are defined. Within the recessed region between the shoulders 45 and 46, a ratchet pawl 47 is disposed. This pawl is movably mounted on a shaft 49, one end of which is carried by a recess in the shoulder 45 and the other by a recess in the shoulder 46. Accordingly, the pawl 47 is mounted whereby it can be rocked between two extreme positions.

A plunger 51 is carried by a generally cylindrical member 53 which passes through a mating cylindrical cavity coaxial with the center of the drive assembly 41. An end of the plunger 51 rides within a plunger-receiving aperture 54 which passes through the member 53. The aperture 54 is radially directed with respect to member 53 and the circular array of the set of ratchet teeth 27. A spring is disposed Within aperture 54 to press adjacent the end of plunger 51 carried within the aperture. Accordingly, the detent is biased outwardly by spring 55. Note that this causes the extending end of the plunger to push against the inner curved portion 57 of the pawl 47.

The plunger 51 may be positioned between two extremes by the rotation of the knurled knob 61, which is coaxial and integral with member 53. As illustrated in FIG. 2, the plunger is at one of these extreme positions. By movement of the knurled knob 61, the plunger can be moved into an analogous position where it rides adjacent the other end of the inner curved portion 57 of the pawl 47.

Shaft 63 is integral with and extends coaxially outwardly from the central portion 43 of wrench drive assembly 41. This shaft passes through an opening in the ear 23b (previously referred to) which is shaped to rotatably receive and provide bearing support for it. A socket wrench engaging stud 65 of rectangular cross section is joined to the shaft 63 and extends outwardly from its end. This stud 65 is conventionally shaped to mate with a socket. Note that it is provided with a conventional springloaded detent 67.

A resilient, fnlsto-conical washer 71 (a so-called Belleville spring) rides on shaft 63 with its opposite ends bearing respectively against the side of central portion 43 of wrench drive assembly 41 and of the inside face of the ear 23b of yoke 23. A conventional snap ring 73 is carried by a suitable groove running about the periphery of shaft 63. The side of this snap ring engages the outer side of ear 23b and retains the shaft assembly 41 and its associated parts in position. Note that the groove for the snap ring 73 is positioned on shaft 63 a suitable distance from the side of the central portion 43 of drive assembly 41 to cause the frusto-conical iwasher 71 to be compressed somewhat. This provides a reactive force by the washer against the central portion 43 of wrench drive assemb y 41.

Attention is directed to the two sets of teeth 75a and 75b which are disposed on opposite outer end regions of the pawl 47. It should be appreciated that either set of these teeth may be engaged as desired with the teeth 27 on the ratchet head by appropriately positioning the knob 61 to cause plunger 51 to assume an appropriate position to urge the desired end of the pawl outwardly.

In operation, with the knob 61 rotated to place the teeth 75a of pawl 47 into engagement with the teeth 27 of the ratchet head 25, rotation of shaft 31 causes the crank member 35 to carry the ball 37 about in a generally circular path, thus resulting in a rocking or side-to-side motion of the ratchet head 25. Accordingly, the teeth 27 on the ratchet head oscillate back-to-forth about the center of the circle on which they are disposed. As the teeth 27 rotate counterclockwise as viewed in FIG. 2, the pawl 47 is carried along by the mutual tooth engagement to cause it to follow the general rotary path of motion of the ratchet head. Accordingly, the drive assembly which carries the pawl is rotated counterclockwise. When the ratchet head 25 rotates in the opposite direction (i.e., clockwise) the teeth 27 push pawl teeth 75a inwardly and free of engagement with the teeth 27. Ratchet action results.

As a result of the motion described above, the rocking action imparted by the shaft, crank means, and ball to the ratchet head causes the wrench drive to rotate in one given direction only. Accordingly, the stud 65 Will drive a socket or other engaged member in a single desired direction of rotation.

When it is desired to reverse the ultimate direction of rotation imparted to the stud 65, it is only necessary to rotate the knob 61 to move the plunger 51 into springloaded engagement with the opposite peripheral inner extremity of pawl 47. This causes the teeth on the pawl previously out of engagement (teeth 75b as seen in FIG. 2) to be moved into engagement with the teeth 27. Ratchet action and drive action in the opposite sense to that previously described will result when the ratchet head 25 is moved.

The frictional engagement of the frusto-conical washer 71 and the side of central member 43 of wrench drive assembly 41 is a significant feature when the wrench engaging stud 65 is not substantially loaded, as when a bolt is turned with little resistance by a socket engaged with the stud 65. Without such frictional engagement sufiicient resistance would not be present to cause the pawl teeth to move out of engagement with the ratchet drive teeth 27 during the ratchet portion of the cycle made by the ratchet drive. Under this condition, ratchet action would not occur and the stud would oscillate backand-forth. But the frictional engagement referred to insures that there is suflicient resistance to the rotation of the wrench drive assembly 41 to cause the pawl teeth to be moved out of engagement during the ratchet portion of the cycle. This insures ratchet action under all conditions, no matter how light the load on stud 65.

Attention is directed to the relationship between the ball member 37 and the projection 35 on shaft 31. This relationship is illustrated in FIGS. 4 and 5 wherein it is seen that the projection 35 is eccentric with respect to the axis A passing through the center of shaft 31. It is further seen that the opening in ball member 37 which mates with the projection 35 is offset or eccentric with respect to the axis B which passes through the center of ball member 37. Accordingly, the ball may assume a variety of positions varying between the extremes illustrated in FIGS. 4 and 5. Thus in FIG. 5, the ball is illustrated in a position such that the eccentricity of its opening causes the axis of the ball to be a maximum distance X with relation to the axis of the shaft 31. On the other hand, FIG. 5 illustrates the ball when it is swung into a position such that its eccentricity causes the distance from the axis of the ball to the axis of shaft 31 to be at a minimum value X.

The load which must be handled by the stud member 65 ultimately determines the extent of displacement of the axis of the ball member 37 with respect to the axis of the shaft 31. Thus in instances where a heavy load is being handled, the comparatively large forces existing between the ratchet head, ball, and projection will cause the ball to assume the shortest displacement possible with respect to the center of the axis of the shaft. Thus a short but powerful stroke results where a maximum of force can be transmitted.

On the other hand, when the forces between the ratchet head, ball, and projection are quite low, as when a bolt is quite easily turned down or withdrawn, the maximum displacement will exist between the center of the ball and the axis of shaft 31. Under these conditions, a long stroke will occur which causes the stud 65 to make the largest possible movement, thus withdrawing or driving a bolt or the like quickly. Under these conditions, the power transmitted is at a minimum although the movement is at a maximum.

Having described the invention in connection with certain specific embodiments thereof, it is to be understood that further modifications may now suggest themselves to those skilled in the art and it is intended to cover such modifications.

What is claimed as new is as follows:

1. A power wrench comprising: a rotatable shaft having at one end thereof a stud connected parallel but eccentrically disposed with respect to the axis of rotation of said shaft, motor means for rotating said shaft, an oscillatory head having an arcuate slot therein, a frame for pivotally carying said head, ball means received by said arcuate slot in said oscillatory head and having an opening eccentric with respect to a diameter of said ball means for rotatably receiving said stud, rotation of said shaft causing oscillation of said head with a varying force and length stroke dependent upon the load imposed thereon, a rotatable wrench drive, and means interconnecting said oscillatory head and said wrench drive for rotating said wrench drive in a selected direction when said head oscillates.

2. The power wrench of claim 1 wherein the axis of rotation of said shaft and the axis of rotation of said wrench drive are perpendicular.

3. The power wrench of claim 1 wherein said oscillatory head is provided with a central, generally-circular opening, the center of which is the center of rotation of said oscillating head, and wherein the means operably interconnecting said oscillatory head and wrench drive have driving engagement with said oscillatory head along the peripheral surfaces defining the said opening in said oscillatory head.

4. The power wrench of claim 3 wherein teeth are carried about the peripheral surfaces of said opening in said oscillatory head, and wherein the said means operably interconnecting said oscillatory head and wrench drive comprises pawl means engaging said teeth when said teeth are moving in one direction, but disengaging therefrom when said teeth are moving in the other direction.

5. A power wrench comprising: a rotatable shaft, motor means for rotating said shaft, an eccentrically disposed projection, parallel to and extending from an end of said shaft, a ball having an opening therein in which said stud is rotatably received, an oscillatory head having a circular opening disposed at its center of rotation and teeth carried about the periphery of said opening, said head having an arcuate slot running transverse the direction of oscillation, said ball being carried in said slot, a frame, a rotatably wrench drive journalized in said frame, springloaded pawl means carried by said wrench drive, said pawl means being engageable with said teeth on said oscillatory head when said teeth are moving in one direction but disengageable from said teeth when said teeth are moving in the opposite direction, and means for placing a restrictive force on said wrench drive to provide ratchet action When said wrench drive is not carrying a substantial load, said opening in said ball being eccentrically located with respect, to the diameter of said ball.

6. A power wrench comprising: a rotatable shaft, motor means for rotating said shaft, an eccentrically disposed projection, parallel to and extending from an end of said shaft, a ball having an opening therein in which said stud is rotatably received, an oscillatory head having a circular opening disposed at its center of rotation and teeth carried about the periphery of said opening, said head having an arcuate slot Iunning transverse the direction of oscillation, said ball being carried in said slot, a frame, a rotatable wrench drive journalized in said frame, spring-loaded pawl means carried by said Wrench drive, said pawl means being engageable with said teeth on said oscillatory head when said teeth are moving in one direction but disengagable from said teeth when said teeth are moving in the opposite direction, means for placing a restrictive force on said wrench drive to provide ratchet action when said Wrench drive is not carrying a substantial load, said means for placing a resistive force on said wrench drive means comprise compressible means for transmitting a force from said frame to said wrench drive means, and said opening in the said ball being eccentrically located with respect to the diameter of said ball.

7. The combination of power transmission mean and a driven member comprising: a rotatable shaft, an eccentrically disposed member carried by said shaft, actuator means rotatably, eccentrically mounted with respect to said member, a driven member rotatably supported to adapt it for oscillation about an axis, and means drivingly connecting said driven member to said actuator means for varying the amount of stroke and the force transmitted to said driven member in dependence upon the load applied to said driven member.

8. The power wrench of claim 1 and further comprising means for placing a resistive force on said wrench drive during oscillation of said head whereby rotation of said wrench drive will occur When said Wrench drive is not carrying a substantial load.

9. A power wrench comprising a rotatable drive shaft, means operatively associated with said drive shaft for rotation thereof, a rotatable wrench drive, eccentric means on said drive shaft, actuator means drivingly connected with said eccentric means on said drive shaft, and oscillating head means drivingly connected with said actuator means and wrench drive for rotating said wrench drive with a progressively varying torque force depending upon the load applied to aid wrench drive, means drivingly interconnecting said oscillating head means and wrench drive imparting intermittent uni-directioal rotation to said wrench drive, said means drivingly interconnecting said oscillating head means and wrench drive including reversible means imparting rotation to said wrench drive in a selected rotational direction.

10. The power wrench as defined in claim 9 wherein said reversible means includes a reversible ratchet assembly interconnecting the wrench drive and oscillating head means, and means placing a resistive force on said wrench drive to assure uni-directional rotation of the wrench drive during oscillation of the oscillating head means.

11. The power wrench as defined in claim 10 wherein said ratchet assembly includes an internal ratchet gear with inwardly facing teeth fixed in relation to the oscillating head means, pawl means carried by said wrench drive and disposed within the internal gear and engaging the teeth on the gear when the gear and oscillating head means are moving in one direction but disengaging therefrom when said teeth are moving in the other direction,

.spring loaded means carried. by said Wrench drive and movably engaged with said pawl means for selective movement between two positions for changing the direction of movement of said teeth in which said pawl means engage said teeth, and a projection connected to said spring loaded means and extending exteriorly of the wrench drive and oscillating head means for manual manipulation thereof to determine the direction of rotation of said wrench drive independently from the direction of rotation of said drive shaft.

12. The power wrench as defined in claim 11 wherein said pawl means includes an arcuate elongated pawl member having arcuate inner and outer edges oriented generally concentrically with the internal gear, ratchet teeth on the end regions of the outer edge of the pawl member, shaft means at the central region of said pawl member rockably supporting the pawl member from the wrench drive to enable the ratchet teeth at selective end regions of the pawl member to be engaged with the internal gear teeth, said spring loaded means including a rotatable cylindrical member journaled in the wrench drive, a plunger slidably received in a diametric bore in said cylindrical member, said plunger including a radially extending end portion engaging the arcuate inner edge of said pawl member, spring means biasing said plunger radially outwardly for rocking said pawl member about the shaft means when the cylindrical member is rotated to shift the plunger from one side of the shaft means to 8 c the other, said projection being in the form of a knob rigid with said cylindrical member for manually reversing the ratchet assembly.

13. A self-contained portable power ratcheting wrench comprising a housing with a substantially circular end member and an elongated handle member, a shaft and power rotor journalled in said elongated handle member, said shaft extending from said elongated handle member into said substantially circular end member, a substantially circular head mounted for oscillatory rotary movement in said circular housing end member, said circular oscillatory head having a circular interior opening therein concentric with the axis of rotary movement thereof in said housing end member for to-and-from movement relative thereto, an annular series of ratchet teeth on the circumference of said oscillatory head interior opening, a work engaging member mounted for rotary movement in the circular opening of said head, pawl means movably mounted on said work engaging member to confront and react with said annular series of ratchet teeth responsive to the to-and-fro rotary movement of said oscillatory head, and complemental interconnecting eccentric means betweeen the end of said power rotatable shaft and said oscillatory head to move the latter to-and-fro responsive to the continuous rotation of said shaft, thereby imparting unidirectional ratcheting movement to said work engaging member, said eccentric means including an eccentrically positioned pin on the end of said shaft and a ball eccentrically mounted with respect to its own diameter on said pin for varying the ratcheting stroke and the force transmitted to said work engaging member in inverse ratio to the turning load thereon.

References Cited UNITED STATES PATENTS 3,167,936 2/1965 Engquist 6429 3,106,274 10/1963 Madsen 64-29 X 3,024,682 3/1962 Finkle 8l52.4 3,205,985 9/1965 Pearl 8l52.4 X 2,826,107 3/1958 Woods 8l52.4

JAMES L. JONES, in, Primary Examiner US. 01. X.R.

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