US3263449A

US3263449A - Impulse tool

Info

Publication number: US3263449A
Application number: US325629A
Authority: US
Inventors: Kramer Leo
Original assignee: Thor Power Tool Co
Current assignee: Thor Power Tool Co
Priority date: 1963-11-22
Filing date: 1963-11-22
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02
Also published as: BE656130A; DE1503100A1; NL6413435A; GB1023088A; CH447073A

Description

L. KRAMER IMPULSE TOOL Aug. 2, 1966 5 Sheets-Sheet 1 Filed Nov. 22, 1965 INVENTOR' Leo Kramer;

Aug. 2, 1966 L. KRAMER 3,263,449

IMPULSE TOOL Filed Nov. 22, 1963 5 Sheets-Sheet 2 INVENTOR. L60 Era/mm;

B Y H H M, m 4 m y L. KRAMER IMPULSE TOOL Aug. 2, 1966 5 Sheets-Sheet 5 Filed Nov. 21;, 1965 INVENTOR. Leo Kramer;

B H1 110 a, 4B M '5 L. KRAMER IMPULSE TOOL Aug. 2, 1966 5 Sheets-Sheet 4.

Filed Nov. 22, 1963 9 W ow 8 m A B 141 4 y a w w w 6 0 w w l i ,IR\\.\HJ WIN/Z l w 5 7 9 g- 2, 66 L KRAMER 3,263,449

IMPULSE TOOL Filed Nov. 22, 1965 5 Sheets-Sheet 5 INVENTOR.

ll 60 fframez BY 4 H Mm, m .4 B Mind 5 United States Patent 3,263,449 IMPULSE TOOL Leo Kramer, Chester, N.J., assignor to Thor Power Tool Company, Aurora, 111., a corporation of Delaware Filed Nov. 22, 1963, Ser. No. 325,629 11 Claims. (CI. 6426) This invention relates to improvements in rotary, power driven, torque applying tools, such as a wrench or the like for driving nuts, bolts, screws or other fasteners.

In a conventional impact wrench, the kinetic energy of a massive rotating hammer member is transferred to a spindle member by repeated collision or striking between cooperating impact jaws on the hammer and spindle. Such tools have well-known disadvantages and limitations, particularly the relatively limited life of the impact jaws and the difliculty in the control of output torque.

In US. Patent No. 3,116,617 by Donald K. Skoog, a different type of tool known as an impulse tool is described and claimed in which the torque generating mechanism includes a pair of non-impacting or non-striking, relatively rotatable, eccentrically spaced members, one of which is driven by a motor and the other of which is adapted to mount a tool such as a nut or bolt engaging socket or the like. The space between the two members is filled with oil or other pressure transmitting liquid, and the internal structure is such that as one member rotates relative to the other, the pressure of the oil rapidly increases and decreases in a cyclic manner so as to create a series of impulses. These impulses are transmitted from the driving member to the driven member through the medium of the oil but without any direct physical impact or collision between jaws or other metal parts.

In my copending application Serial No. 250,160, filed January 8, 1963, now US. Patent No. 3,214,940, certain improvements in an impulse tool of the foregoing type are described and claimed, said improvements relating primarily to the internal mechanism responsible for the generation of the impulses. However, in each instance the tool mechanism involves an eccentric rotating memher which may tend to impart undesirable effects under certain conditions. The present invention relates to additional improvements where by I am able to eliminate the use of an eccentric rotating mass so as to provide a tool having a symmetrical structure and a balanced operation.

Accordingly, a primary object of the invention is to provide a novel and improved impulse tool of the general character described above.

A further object of the invention is to provide, in an impulse tool of the general character described, novel and improved means for obtaining impulses which does not involve the use of an eccentric rotating mass.

A more specific object of the invention is to provide, in an impulse tool of the aforementioned general character, an improved impulse generating means having a symmetrical structure and a balanced operation.

Other objects and advantages of the invention will become evident from the subsequent detailed description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front end elevational view of a tool comprising one specific embodiment of the invention;

FIG. 2 is a side elevational view, partially in section, taken along the line 22 of FIG. 1;

FIG. 3 is a reduced scale end elevational view of a portion of the internal mechanism of the tool as seen along the line 3-3 of FIG. 2;

FIG. 4 is a view similar to FIG. 3 but taken at the op posite end of the internal mechanism along the line 4-4 of FIG. 2;

FIG. 5 is an enlarged scale horizontal sectional view of the internal mechanism taken along the line 55 of FIG. 2;

FIG. 6 is a transverse sectional view taken along the line 66 of FIG. 5;

FIGS. 7-9 are reduced scale sectional views, generally similar to FIG. 6, showing successive operating positions of the internal mechanism of the tool;

FIG. 10 is a sectional view generally similar to FIG. 5 but showing a modification of the invention;

FIG. 11 is a sectional view taken along the line 11-11 of FIG. 10;

FIG. 12 is a sectional view generally similar to FIG. 5 but showing a second embodiment of the invention;

FIG. 13 is a sectional view taken along the line 1313 of FIG. 12; and

FIGS. 14l6 are reduced scale sectional views showing successive operating positions of the second embodiment.

For the sake of convenience, the present invention is illustrated in connection with a rotary power driven wrench or nut setter, but it will be understood that the principles of the invention which pertain to the torque generating or impulse unit may be utilized to advantage in a wide variety of power tools.

Referring first to FIGS. 1 and 2, the tool has a front casing section 21 and a rear casing section 22 with 3. depending handle portion 23, the front and rear casing sections being detachably connected, as by a plurality of cap screws 24. The rear casing section 22 contains a rotary air-actuated motor of a conventional type designated generally at 26. An air hose (not shown) may be connected to an air inlet connection 27 at the lower end of the handle portion 23, and the air supply to the motor as is controlled by means of a throttle valve assembly 28 movably mounted in the handle portion 23 and operable by a depressible trigger 29 for regulating the operation of the tool. An impulse unit 31 is contained within the front casing section 21, as hereinafter described in greater detail. The impulse unit 31 has a rotatable spindle with an elongated forward shaft portion 32 journaled in a hearing or bushing 33 which is mounted in an opening in the forward end of the casing section 21. The outer terminus of the spindle portion 32 is provided with a square end 34 having a depressible detent 35 for detachably mounting a nut-or bolt-engaging socket or other tool member.

Referring particularly to FIGS. 36, the impulse unit 31 comprises a housing assembly, indicated generally at 41, which is adapted to be driven by the air motor 26, and an internal spindle 42 having the forwardly projecting shaft portion 32 heretofore mentioned.

The housing assembly 41 includes an outer casing 43 having a flanged forward end 44 and an internally threaded rear end portion 46. A cylinder bushing 47 (FIGS. 5 and 6) having a generally elliptical or oval shaped internal cylinder cavity 48 is tightly fitted within the outer casing 43 and is disposed between a pair of forward and rear cap members 49 and 51 (FIG. 5), respectively, with O-ring seals 52 mounted in suitable grooves in the inner faces of the respective cap members opposite the axial ends of the bushing 47. The forward cap member 49 abuts the flange 44 and has a forwardly projecting tapered bearing portion 53 with a bore 50 which receives the spindle shaft portion 32. A rotary O-ring seal 54 is mounted in an annular groove 55 in the bearing portion 53. An annular locking ring or nut 56 threadedly engages the casing opening 46 and abuts the rear cap member 51 for retaining the impulse unit 31 in unitary assembled relation. The front and

rear cap members

49 and 51 are retained in predetermined orientation with respect to the elliptical cavity 48 of the bushing 47 by means of a plurality of roll pins 3 57 and 58 (FIGS. 3 and 4) which are fitted in suitable openings in the bushing and the respective cap members. As seen in FIG. 4, the inner periphery of the locking ring or nut 56 is provided with a plurality of recesses or serrations 59 so that after the nut 56 has been tightened to the desired extent, a set screw 60 can be inserted through one of the recesses 59 and threaded into a selected one of a plurality of threaded sockets 61 in the rear cap member 51 for locking the nut 56 in its tightened position.

The spindle 42 has an enlarged central portion 62 with a circular cross-sectional configuration disposed coaxially within the elliptical cylinder cavity 48 of the bushing 47, as best seen in FIG. 6. A short integral stub shaft portion 63 (FIG. projects rearwardly from the spindle portion 62 and is journaled in a socket 65 provided in a projecting boss portion 66 on the rear cap member 51. The opposite end of the spindle 42 is journaled in the bearing portion 53 of the front cap member 49 by means of the elongated integral shaft portion 32 (FIG. 5) heretofore described. The

spindle shaft portions

32 and 63 are coaxial with the axis of rotation of the housing assembly 41.

The elliptical cylinder cavity 48 of the bushing 47 is filled with a suitable oil or other pressure transmitting liquid, and a detachable fill plug 71 (FIGS. 3 and 5) is provided in the front cap member 49 for filling the cavity 48 with oil. A removable vent plug 72 (FIG. 3) is also provided in the cap member 49 adjacent the plug 71 for venting air from the cavity 48 during the introduction of oil. The rear cap member 51 has a hexagonal drive connection 73 (FIG. 5) projecting from the boss portion 66 and engaging a driving socket connection 74 (FIG. 2) on the air motor 26. Thus, when the air motor 26 is in operation, the housing assembly 41 (comprising 43, 47, 49, 51, and 56) of the impulse unit 31 is rotated and, as described in detail below, fluid pressure impulses are generated in and are transmitted through the oil medium to the spindle 42.

The elliptical cavity 48 of the bushing 47 is provided with a pair of circumferentially extending recesses or undercuts, as designated at 81 (FIGS. 5 and 6), intermediate the opposite ends of the bushing 47. These circumferential recesses 81 are interrupted by a pair of axially extending lands or seal points 82 diametrically disposed at the longer or major axis of the elliptical cavity 48 and also by a similar pair of lands or seal points 83 disposed at the shorter or minor axis of the cavity. Thus, the distance between the lands 82 is appreciably greater than the distance between the lands 83. Moreover, as shown in FIG. 6, the diameter of the circular spindle portion 62 is such that there is only a slight clearance between the spindle portion 62 and the lands 83 at the minor axis of the cavity 48.

The circular spindle portion 62 is provided with four radially extending slots 86 disposed at equal circumferential spacings around the spindle, and each slot 86 has an elongated blade 87 slidably mounted in closefitting relation therein with the blades 87 extending the full axial length of the spindle portion 62 and spanning the recesses 81, as best seen in FIG. 5. The base or innermost end of each slot 86 is enlarged in the form of a circular axial-1y extending bore 88 (FIG. 6) so that the slot 86 and its connecting bore 88 have a keyhole shape in cross-section. Each bore 88 communicates with the outer periphery of the spindle portion 62 through a pair of fluid pressure loading passages 89 machined in the spindle at one side of the corresponding slot 86. As shown in FIG. 6, the passages 89 are arranged in opposed relation at adjacent sides of a pair of blades 87 so that the corresponding bores 88 of each pair of blades 87 are placed in fluid communication with the same region of the oil filled cavity 48, for the purpose hereinafter described in greater detail. A pair of compression springs 91 bear against the inner wall portion of each bore 88 and extend into a pair of bores 93 extending from the inner edge of each blade 87 for normally urging the blades 87 outwardly into contact with the wall of the bushing cavity 48. As best seen in FIG. 6, the outer edge of each blade portion 87 is rounded or curved, as at 94, to provide intermittent sealing engagement with the

lands

82 and 83 during relative rotation of the housing assembly and the spindle.

Referring now to FIGS. 7-9, a typical operating cycle of the tool will be described. It will be assumed that the housing assembly 41, including the bushing 47, is being driven in a counter-clockwise direction by the air motor 26, as indicated by the arrow. The square end 34 on the forward spindle shaft 32 is assumed to be in engagement through a suitable socket (not shown) with a fastener element (not shown) such as a nut or bolt which is to be tightened. At the outset of the tightening operation, very little torque resistance is encountered by the spindle and, consequently, the frictional engagement of the spring-pressed blades 87 with the inner wall of the bushing cavity 48 is sufiicient to cause the spindle 42 to rotate in a counter-clockwise direction in unison with the rotating housing assembly 41.

As tightening of the fastener element proceeds and substantial torque resistance is encountered by the rotating spindle 42, the housing assembly 41 begins to rotate relative to and ahead of the spindle 42. In the position of the mechanism shown in FIG. 7 the housing assembly 41 has rotated in a counter-clockwise direction relative to the spindle 42 so that the lands or seal

points

82 and 83 have just left the outer ends 94 of the blades 87, which are separately identified as 87a, 87b, 87c, and 87:1. The zones designated at 95 in the elliptical cavity 48 between

blades

87a and 870 and between

blades

87b and 87d are gradually decreasing in volume, whereas the zones designated at 95 in the cavity 48 between

blades

87a and 87d and between

blades

87b and 87c are gradually increasing in volume. However, since the blades 87 are out of engagement with the seal points 82 and 83, the oil or other pressure transmitting fluid in the cavity 48 is free to flow between the

zones

95 and 95 through the recesses or undercuts 81 so that the pressure throughout the cavity 48 is substantially uniform. Thus, the motor 26 continues to accelerate the housing 41 about the spindle 42.

In FIG. 8 the housing 41 has rotated not quite from its FIG. 7 position so that the

lands

82 and 83 are aligned with the blades 87. However, in this position the more closely spaced lands 83 have caused the oppositely disposed pair of

blades

87a and 87b to be cammed or depressed substantially fully into their slots 86 and bores 88 and thereby causing the corresponding springs 91 to be substantially fully collapsed. At this point, zones of the cavity 48 are now increasing in volume and zones 95 are decreasing in volume. However, since the inner edges of the other pair of

blades

87c and 87d are in fluid communication, through passages 89 and bores 88, with the relatively lower pressure expanding zones 95, it will be evident that the relatively greater fluid pressure in the contracting zones 95 will tend to depress the

blades

87c and 87d inwardly in their slots against the spring action, as shown in slightly exaggerated form in FIG. 8. Thus, fluid in the cavity 48 is free to flow between the

zones

95 and 95 at opposite sides of the

blades

87c and 87d so that the fluid pressure throughout the cavity 48 is again essentially uniform and the housing 41 continues to accelerate ahead of the spindle 42. As the housnig 41 rotates beyond its FIG. 8 position, the

lands

82 and 83 will once again pass beyond the blades 87 so that fluid pressure is again equalized throughout the cavity 48 by reason of the recesses 81.

In FIG. 9 (which also corresponds to FIG. 6) the housing 41 has rotated through approximately or one-half revolution from its FIG. 7 position, and just before reaching the FIG. 9 position the zones 95 are again decreasing in volume while the zone 95' are increasing in volume. When the FIG. 9 position is reached wherein the

lands

82 and 83 are again aligned with the blades 87, it will be seen that the inner edge of each blade 87 is subjected, through the passages 89 and the bores 80, to the relatively high fluid pressure of the contracting zones 95. Consequently, all four blades 87 are simultaneously subjected to pressure loading by high pressure fluid and are, therefore, urged outwardly by the combined action of fluid pressure and the springs 91 so that the outer blade edges 94 are pressed into dynamic sealing relation with respect to the moving

lands

82 and 83 and fluid is no longer free to pass between the

zones

95 and 95 through the recesses 81. As a result of this sudden sealing-off of the fluid, a momentary substantial increase in fluid pressure is obtained in the zones 95 of the cavity 48, as indicated by the letter H in FIG. 9 to designate the high pressure zones. In the other sealed-off zones 95 of the cavity 48, the fluid pressure is substantially lower, as designated by the letter L to indicate the low pressure zones. In a typical example, the pressure in the zones 95 may be as high as 3,000 lbs. per square inch.

By the time the housing 41 reaches the dynamic sealing position of FIG. 9 it has acquired considerable moment-um since it has been accelerating through substantially 180. Consequently, the pressure in zones 95 will continue to rise until the housing has lost its momentum or until the

lands

82 and 83 have moved beyond the blades 87. This momentary pressure increases in the zones 95 imposes an eccentric force on the blade 87 and thereby causes the spindle 42 to rotate in a counterclockwise direction to tighten the fastener element.

As the housing assembly 41 rotates beyond its FIG. 9 position ahead of the spindle 4 2, the fluid pressure in the cavity 48 is again ubstantially equalized by reason of the free fluid communication provided by the recesses or undercuts 81 once the moving parts have passed beyond the dynamic seal position. This condition prevails until the housing has rotated 180 to another dynamic sealing position which is just prior to the FIG. 7 position of the mechanism. Continued rotation of the housing assembly 41 causes the foregoing cycle to be repeated with the result that successive pressure increases are generated in the high pressure zones 95 of the cavity 48 each half revolution of the housing, -i.e. each time the lands 82 are aligned with the

blades

87a and 87b, and these pressure increases result in impulses which are imparted to the spindle 42 through the medium of the fluid and the blades 87 until the desired tightening operation has been completed.

Because of the rapid rotation of the housing assembly 4-1, it will be understood that the dynamic sealing relationship described above is repeated over and over again. However, to insure proper operation of the tool, it may be desirable to provide a small static leakage between the relatively rotatable housing assembly 41 and spindle 42. For example, in assembling the impulse unit 31, the casing nut 56 is tightened sufliciently to retain the inner faces of the end cap members 4 9 and 51 in dynamic sealing relationship with the opposite axial ends of the spindle portion 62, but the operating clearance therebetween is sufficient to allow a predetermined static leakage between the high and low pressure zones of the cavity 48. This relationship is desirable in order to insure that excessive driving torque from the air motor 26 will not be required in order to rotate the housing assembly 41 beyond one of its dynamic sealing positions such as illustrated in FIGS. 6 and 9.

As a further aid in this respect, the inner face of one, and preferably both, of the housing cap members, such as the cap 49, may be provided with appropriately located grooves of predetermined dimensions which are capable of transmitting fluid pressure between the high and low pressure sides of the

blades

87a and 87b when the operating parts are in dynamic sealed relation. The use of a metering groove for this purpose is described in more detail in my aforementioned copending application Serial No. 250,160.

To reverse the operation of the tool, the direction of rotation of the air motor 26 is reversed, thereby rotating the housing assembly 41 in the opposite direction and consequently interchanging the high and low pressure zones and 95' illustrated in FIGS. 7-9, but the operation is otherwise the same as hereinabove described. Thus, the mechanism is readily reversible and proper pressure loading of the blades 87 is not dependent upon the operation of a check valve or the like in an internal fluid pressure passageway.

Although in the illustrated embodiment the housing assembly 41 is driven by the air motor 26 and the spindle 42 drives the tool member, it will be appreciated that these functions may be interchanged by minor and obvious modifications of the structure. Thus, the rear spindle shaft portion 63 can be connected to the air motor 26 and the forward cap member 49 of the housing assembly 41 can be modified to mount the tool member.

One of the principal advantages of an impulse tool, in addition to the elimination of impacts or collisions between metal parts, is the facility with which such an impulse mechanism lends itself to the control of output torque of the tool. Certain minor provisions for controlling the pressure differential between the high and low pressure sides of the impulse unit have been described above for the purpose of minimizing the torque requirements of the air motor 26. However, in order to provide a positive upper limit on the torque output of the impulse unit, an adjustable pressure relief valve is preferably provided which will prevent the fluid pressure in the high pressure zones from exceeding a predetermined maximum.

One such pressure relief arrangement is shown in FIGS. 5 and 6 and comprises a centrally located axial bore 96 in the spindle portion 62. At the forward end of the spindle portion 62 the bore 96 communicates with an elongate-d smaller diameter bore 97 having a threaded portion 98. At the opposite or rearward end of the spindle portion 62 the bore 96 is closed by means of a plug or cap 99 which is keyed by a pin 101. The inner end portion of the plug 99 has an axial recess 102 with a plurality of lateral or radial ports 103. The inner axial end of the plug 99 provides an annular shoulder 108 constituting a valve seat for a ball element 109. High pressure fluid from the zones 95 or H communicate with the recess 102 through a pair of radial angular drilled passages 111 in the spindle portion 62. The inner ends of the passages 111 are aligned with the enlarged ports 103 in the plug 99. The ball element 109 is normally retained in seated relation on the shoulder 108 by means of a spring 112 having its inner end operatively engaging the ball 109 through a cap member 113. The opposite end of the spring 112 seats against a flange 114 of a piston member 116 disposed adjacent the forward end of the bore 96. The piston 116 has another flange 117 spaced from the flange 114 with an O-ring seal 118 mounted therebetween. An adjusting screw 121 is mounted in the threaded portion 98 of the small bore 97 and engages the outer end of the piston 116 for regulating the position of the piston 116 within the bore 96 and the degree of compression Of the spring 112. The bore 97 extends forwardly the length of the spindle and is accessible at the front end of the square 34 (FIGS. 1 and 2) so that a suitable elongated tool, such as an Allen wrench can be inserted in the bore 97 for adjustment of the screw 121.

When high pressure fluid in the recess 102 exceeds a predetermined pressure, which is dependent upon the pressure exerted by the spring 112 as determined by the adjusting screw 121, the ball 109 is disengaged from its seat 108 and the high pressure fluid bleeds into the bore 96 and thence through another pair of drilled radial angular passages 122 in the spindle portion 62 into the low pressure zones L or 95 of the cavity 48. Thus, when the spindle 42 encounters a predetermined torque resistance during a tightening operation, the pressure in the high pressure zones H or 95 of the cavity 48 will tend to build up because of the limited rotatability of the spindle at which point the relief ball valve 109 will open so as to prevent the imposition of excessive torque on the (fastening element.

To recapitulate, it will be understood from the foregoing description that the present invention affords an improved impulse generating mechanism in which the relatively rotating parts are mounted coaxially and are in symmetrical or non-eccentric arrangement relative to the common axis of rotation. Thus, broadly speaking, the mechanism includes (1) a pair of relatively rotatable, coaxial, non-eccentric members having a fluid filled cavity therebetween, (2) a plurality of symmetrically disposed spring-pressed blades or vanes slidably mounted on one of the members and extending into the fluid-filled cavity and (3) a plurality of symmetrically disposed seal points on the other member arranged for periodic engagement with the blades at non-uniform distances from the common axis of rotation. Upon relative rotation between the members, the fluid-filled cavity is intermittently divided into zones which are alternately increasing in volume (low pressure) and decreasing in volume (high pressure). A fluid pressure loading arrangement is also provided for the blades such that, at certain of the periodic conditions of alignment between the blades and the seal points, each blade is subjected to the high fluid pressure of a contracting zone of the fluid-filled cavity whereby to provide a momentary dynamic sealing relation between the relatively rotating members. Consequently, the momentary large pressure increases necessary for impulse generation are obtained. As a result of the symmetrical non-eccentric relationship of the rotating parts, no eccentric forces are developed and the impulse mechanism of the tool operates under a balanced load. Such uniform balanced operation avoids unbalanced forces on the bearings and insures a balanced pressure condition at the housing end plates or caps of the impulse unit. In many cases, the tool operating under balanced load will also be more comfortable and less tiring for the operator.

FIGS. 10 and 11 illustrate a modification of the impulse mechanism 31 previously described in that the pressure relief valve for torque control is mounted in the housing means of the impulse unit rather than in the spindle. Otherwise identical parts in FIGS. 10 and 11 are identified by the same reference numerals used in the comparable FIGS. and 6. Thus, in FIGS. and 11 one of the thick wall portions of the bushing 47 is provided with an axial bore 126 having a plug 127 at its rearward end adjacent the end cap 51. The plug 127 has an axial recess 128 and a plurality of radial apertures or ports 129. A ball element 131 is held in normally seated engagement against an end seat 132 on the plug 127 by means of a spring 133 and a cap 134. The forward end of the spring 133 is engaged by an adjustably positioned piston 136 having spaced flanges 137 and 138 with an O-ring seal 139 therebetween. An adjusting screw 141 is mounted in a threaded opening 142 in the end cap 49 and engages the piston 136. A tension plug 143, of nylon or the like, is provided in the cap member 49 and engages the threads of the screw 141 for retaining the latter in adjusted position. Of course, in this modification the

spindle shaft portions

32 and 63 are solid and integral with the main spindle portion 62.

In this case the spindle portion 62 has a pair of

diametric bores

146 and 147 arranged at right angles so as to interconnect the two high pressure zones 95 or H and the two low pressure zones 95' or L, respectively, when the mechanism is in dynamic sealing relation as shown in FIG. 11. The bushing 47 also has a pair of

angular passages

148 and 149 extending from the bore 126 at opposite sides of the valve seat 132 to opposite sides of one of the lands 83 and thereby connecting-the bore 126 with the high and low pressure zones and 95', respectively, of the elliptical cavity 43 when the unit is in dynamic sealing position. Thus, at impulse position when fluid pressure in the zones 95 or H exceeds the maximum determined by the spring adjustment, high pressure fluid can pass from the interconnected zones 95 or H through passage 148 and ports 129 into the recess 128 and, upon displacement of the ball 131 from its seat 132, the high pressure fluid bleeds through the passage 149 and thence into the interconnected low pressure zones 95' or L. If desired, an empty axial bore (not shown) may be provided in the opposite thick wall portion of the bushing 47 diametrically across from the bore 126 in order to balance the weight of the unit and insure uniform balanced operation. Reference is made to my previously mentioned copending application Ser. No. 250,160 for an illustration of this feature.

FIGS. 12 to 16 show another embodiment of the invention which differs from the previously described structure in that: (1) the housing cavity of the impulse unit is circular in cross-section and the spindle body is substantially oval or elliptical in cross section instead of the reverse relationship shown in FIGS. 1 to 11, (2) the slidable blades or vanes are mounted in slots in the housing rather than in the spindle, and (3) the spindle is driven by the air motor of the tool and the housing is utilized as the output portion of the tool instead of the opposite arrangement heretofore illustrated and described.

The housing assembly, designated at 151, includes an outer casing 152, a rigidly fitted cylinder bushing 153 having a circular cavity 154, a forward end cap 156, a rear end cap 157, and a locking ring 158 threadedly engaging the casing 152 for retaining the impulse unit in assembled relation. A spindle, designated generally at 159, has a central body portion 161 of substantially oval or elliptical cross-sectional configuration which is disposed coaxially within the cavity 154. A shaft portion 162 at the forward end of the spindle 159 is journalled in a recess 163 in the end cap 156, and a shaft portion 164 at the rearward end of the spindle 159 is journalled in a bore 166 in the end cap 157. The rear shaft portion 164 of the spindle is provided with a non-circular socket 167 for driving engagement with the air motor of the tool.

A plurality of blades or vanes 168 are slidably mounted in slots 169 in the bushing 153 which extend outwardly from the wall of the cavity 154 and terminate in enlarged axially extending bores 171 having connecting pressure loading passages 172 for communicating fluid pressure from the cavity 154 to the outer edges of the blades 168. Each blade 168 has associated therewith a pair of compression springs 173 extending between the outer wall of the corresponding bore 171 and a pair of spaced bores 174 in the outer edge of the blade whereby the blade is normally urged inwardly into contact with the elliptical spindle portion 161. The peripheral surface of the elliptical spindle portion 161 is provided with an encircling recess or undercut 176 which is disposed centrally between the axial ends of the spindle portion 161 and is interrupted by a pair of axially extending lands or seal points 177 disposed at the ends of the major axis of the ellipse and also by a pair of lands or seal points 178 disposed at the minor axis of the ellipse. The major axis dimension of the elliptical spindle portion 161 is such that there is only a slight clearance between the spindle portion 161 and the circular cavity 154.

The operation of the impulse generation unit is in all respects analogous to the operation heretofore described in detail in connection with the previous embodiments. Thus, referring particularly to FIGS. 14-16, an impulse position is obtained every half revolution when the

lands

177 and 178 are in dynamic sealing relation with the blades 168. Assuming rotation of the spindle 159 by the air motor in a clockwise direction, the spring pressure of the blades 168 against the periphery of the spindle por- 9 tion 161 is sufficient at the outset of operation to effect clockwise rotation of the housing 151 and also the wrench socket or other tool member which is secured to the forward end (not shown) of an axial extension 179 on the end cap 156. As torque resistance on the extension 179 increases, the spindle 159 begins to accelerate ahead of the housing 151. At the position shown in FIG. 14 the volumes of the upper left quadrant (between blades 168a and 168C) and the lower right quadrant (between blades 1681; and 168d) of the cavity 154 are decreasing and the volumes of the remaining quadrants are increasing. However, fluid pressure is equalized between adjacent contracting and expanding zones by reason of the recess 176. In FIG. 15 the

lands

177 and 178 are approaching alignment with the respective blades 168, and blades 1680 and 168d are substantially fully depressed by the camming action of the lands 177. However, because of the orientation of the pressure loading passages 172, only low pressure fluid from the now expanding zones of the upper left and lower right quadrants of cavity 154 has access to the outer edges of the blades. Consequently, there is no pressure seal and high pressure fluid in the remaining contracting quadrants can force the blades 168 outwardly to equalize the pressure. As the spindle continues to rotate ahead of the housing, the zones in the upper left and lower right quadrants start to decrease in volume and finally the position of FIG. 16 is reached in which the lands 177 are aligned with blades 168a and 16811 and the lands 178 are aligned with

blades

168a and 168d. At this position the outer edge of each blade is exposed to high pressure fluid from a contracting zone and a dynamic seal is achieved between the blades 168 and the lands 177-178. The cycle is repeated in the same manner so that an impulse is imparted to the housing 151 through the blades 168 every half revolution of the spindle relative to the housing.

A pressure relief valve arrangement for torque control is provided in a bore 181 extending axially of the spindle 159 in essentially the same manner as shown in FIGS. and 6 so that a detailed description is unnecessary. High pressure fluid from the high pressure zones of the cavity 154 communicates with the upstream side of the relief valve bore 181 by means of a pair of drilled passages 182 in the elliptical spindle portion 161, and such fluid is vented from the downstream side of the relief valve through another pair of spindle passages 183 into the low pressure zones of the cavity 154. The spring setting for the relief valve is adjusted by means of a screw 186 threaded into the spindle shaft 162 and accessible from the front end of the tool through an elongated axial passage 187.

Although the invention has been described with particular reference to certain specific structural embodiments thereof, it should be understood that other modifications and equivalent structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In an impulse tool, an improved impulse generating means comprising a rotatable housing member having a symmetrical, non-eccentric, coaxial, internal cavity containing a pressure transmitting fluid, a spindle member rotatably disposed in coaxial non-eccentric relation in said cavity for relative rotation between said housing member and said spindle member, means on one of said members defining a plurality of fluid pressure sealing portions disposed in symmetrically spaced relation around said cavity, a plurality of movable elements carried by the other of said members in symmetrically spaced relation around said cavity, the configurations of said cavity and said spindle member being such that, during relative rotation of said members, said fluid pressure sealing portions and said movable elements are engageable at different distances from the axis of rotation of said members whereby to divide said cavity into a plurality of zones of alternately increasing and decreasing volume,

and fluid passage means in said other member for simultaneously communicating the resultant increasing fluid pressure from the zones of decreasing volume to all of said movable elements at certain predetermined relative rotational positions of said members so as to urge said movable elements into momentary sealing relation with said fluid pressure sealing portions, whereby to generate intermittent substantial fluid pressure increases in sealedoff portions of fluid in said zones of decreasing volume and thereby transmitting rotational torque impulses through said fluid between said members.

2. The structure of claim 1 further characterized in that said other member is provided with a plurality of symmetrically spaced slots and said movable elements comprise blades extending axially of said cavity and radially slidable in said slots, and spring means is provided in said slots for normally urging said blades outwardly of said slots and in engagement with said one member whereby said blades are adapted to span said cavity between said members for defining said zones.

3. The structure of claim 2 further characterized in that said fluid passage means comprises a plurality of fluid passages in said other member communicating between said cavity and the base portions of said slots behind said blades, and said fluid passages being disposed relative to said members and said blades so as to register said fluid pas-sages with said zones of decreasing volume during said certain predetermined positions of said members.

4. The structure of claim 1 further characterized in that One of said housing or spindle members is provided with adjustable pres-sure relief valve means and is also provided with a plurality of fluid passages communicating said valve means with said zones of increasing volume and with said zones of decreasing volume when said movable elements and said fluid pressure sealing portions are in sealing relation, whereby to prevent fluid pressure in said zones of decreasing volume from exceeding a predetermined maximum.

5. The structure of claim 1 further characterized in that said cavity is generally elliptical in cross-section, and said spindle member has a circular cross-section.

6. The structure of claim 5 further characterized in that four fluid pressure sealing portions are provided on said housing member in opposed relation at the major and minor axes of the elliptical cavity, and said movable elements comprise four blades slidably mounted in uniformly spaced relation around the periphery of said spindle member.

7. The structure of claim 6 further characterized in that said housing member has means for drivingly connecting the same to a rotary motor and said spindle member has means for connecting the same to a tool element.

8. The structure of claim 1 further characterized in that said cavity is circular in crosssection, and said spindle member has a generally elliptical cross-section.

9. The structure of claim 8 further characterized in that four fluid pressure sealing portions are provided around the periphery of said spindle member at the ends of the major and minor axes thereof, and said movable elements comprise four blades slidably mounted in said housing member in uniformly spaced relation around said cavity.

10. The structure of claim 9 further characterized in that said spindle member has means for drivingly connecting the same to a rotary motor and said housing member has means for connecting the same to a tool element.

11. An impulse generating mechanism for use in a rotary tool or the like, comprising a pair of relatively rotatable members having a common axis of rotation, said members being symmetrical relative to said axis and defining a cavity therebetween containing a pressure transmitting fluid, and means on one of said members providing a plurality of points of sealing engagement with the other of said members during relative rotation therebetween, said points of engagement being disposed in symmetrically spaced relation around said axis and the configurations of said members and said cavity being such that, during relative rotation of said members, said points of sealing engagement are disposed at diiferent distances from said axis, whereby to divide said cavity into a plurality of zones of alternately increasing and decreasing volume and thereby generating intermittent substantial fluid pressure increases in sealed-off portions of fluid in said Zones of decreasing volume.

References Cited by the Examiner UNITED STATES PATENTS Fischer 192-58 Rich 19258 Bredlow et al 19258 Treer 19258 Ramsey 192-58 Skoog 6426 10 MILTON KAUFMAN, Primary Examiner.

BROUGHTON G. DURHAM, Examiner.

H. C. COE, Assistant Examiner.

Claims

1. IN AN IMPULSE TOOL, AN IMPROVED IMPULSE GENERATING MEANS COMPRISING A ROTATABLE HOUSING MEMBER HAVING A SYMMETRICAL, NON-ECCENTRIC, COAXIAL, INTERNAL CAVITY CONTAINING A PRESSURE TRANSMITTING FLUID, A SPINDLE MEMBER ROTATABLY DISPOSED IN COAXIAL NON-ECCENTRIC RELATION IN SAID CAVITY FOR RELATIVE ROTATION BETWEEN SAID HOUSING MEMBER AND SAID SPINDLE MEMBER, MEANS ON ONE OF SAID MEMBERS DEFINING A PLURALITY OF FLUID PRESSURE SEALING PORTIONS DISPOSED IN SYMMETRICALLY SPACED RELATION AROUND SAID CAVITY, A PLURALITY OF MOVABLE ELEMENTS CARRIED BY THE OTHER OF SAID MEMBERS IN SYMMETRICALLY SPACED RELATION AROUND SAID CAVITY, THE CONFIGURATIONS OF SAID CAVITY AND SAID SPINDLE MEMBER BEING SUCH THAT, DURING RELATIVE ROTATION OF SAID MEMBERS, SAID FLUID PRESSURE SEALING PORTIONS AND SAID MOVABLE ELEMENTS ARE ENGAGEABLE AT DIFFERENT DISTANCES FROM THE AXIS OF ROTATION OF SAID MEMBERS WHEREBY TO DIVIDE SAID CAVITY INTO A PLURALITY OF ZONES OF ALTERNATELY INCREASING AND DECREASING VOLUME, AND FLUID PASSAGE MEANS IN SAID OTHER MEMBER FOR SIMULTANEOUSLY COMMUNICATING THE RESULTANT INCREASING FLUID PRESSURE FROM THE ZONES OF DECREASING VOLUME TO ALL OF SAID MOVABLE ELEMENTS AT CERTAIN PREDETERMINED RELATIVE ROTATIONAL POSITIONS OF SAID MEMBERS SO AS TO URGE SAID MOVABLE ELEMENTS INTO MOMENTARY SEALING RELATION WITH SAID FLUID PRESSURE SEALING PORTIONS, WHEREBY TO GENERATE INTERMITTENT SUBSTANTIAL FLUID PRESSURE INCREASES IN SEALEDOFF PORTIONS OF FLUID IN SAID ZONES OF DECREASING VOLUME AND THEREBY TRANSMITTING ROTATIONAL TORQUE IMPULSES THROUGH SAID FLUID BETWEEN SAID MEMBERS.