Patent GB-1498652-A (GB)
Title: Impact wrench
IPC: B25B21/02
Filed: 1975-03-05
Abstract: 1498652 Impact wrenches VSES N I I PROEKTNOKON - STRUKTOR INST MEKHANIZIROVAN I RUCH STROITELNO - MONTAZH INSTRUMENTA VIBRATOROV I STROITELNO - OTDELOCH MASHIN 5 Mar 1975 9204/75 Heading B3N An impact wrench comprises a housing, a hammer mounted in the housing for rotation about an axis and having impact jaws, an anvil mounted in the housing for rotation about said axis and having impact jaws and an output spindle, the hammer jaws being spaced axially from the anvil jaws when the wrench is at rest, and drive means for rotating said hammer about said axis, the wrench being arranged such that, in response to rotation of said hammer by said drive means, said hammer jaws (or a part of the hammer) are (or is) axially displaced towards the anvil jaws, the hammer and anvil having respective portions which interact when said hammer jaws are in a predetermined angular relation to said anvil jaws once the hammer jaws (or said part of the hammer) have (or has) been displaced axially towards the anvil jaws by at least a predetermined distance from their (or its) rest position-representing attainment by the hammer of a predetermined angular velocity-the interaction of said respective portions causing the hammer jaws and anvil jaws to accelerate relatively towards each other parallel to said axis whereby said hammer jaws deliver an impact to said anvil jaws, the wrench further comprising means for disengaging the jaws after impact. In the embodiments of Figs. 2, 6, 11, 16, 20, 30 and 35 the hammer jaws are axially displaced towards the anvil while in the embodiments of Figs. 1, 45 and 46 the reverse is true. In Fig. 2, friction clutch 21 interconnects shaft 9 with axially fixed hammer "driving part" 18. Axially movable hammer "driven part" or body 17a, b, upwardly urged by spring 29, supports at projection 30, centrifugally acting flyweights 31 which carry jaws 6 and engage driving part 18 at inclined surfaces 26, 33 and a flanged bush 37, spring loaded away from anvil 5 engages in flyweights 31 at notches 36, 38. Under drive, rotation of the weights 31 causes axial movement due to interengaging inclined surfaces 26, 27, 33 and hammer part 17 moves downwardly, cam surfaces 35, 44 on jaws 6, 7 interact to cause disengagement of the flyweights from projections 30 on part 17b. Flyweights 31 and bush 37 then move towards anvil 5 and jaws 6 and 7 fully engage. After rotational energy is lost on impact springs 29, 42 reset the hammer. In Fig. 6, hammer driven part 17 carries a relatively axially movable sleeve 49 normally axially locked by radial members 52 and carrying the jaws 6. Balls 55 engage members 52 and are engageable by projections (59), Fig. 10, not shown, on the end of anvil tube 58. Under drive, flyweight rods 60 move outwardly in radial slots (51), Fig. 9, not shown, bear against inclined surfaces 57, 56 on part 18 and sleeve 49 to cause axial movement of part 17 and sleeve 49 together against spring 22 until projections (59) force balls 55 radially to unlock members 52, whereupon sleeve 49 moves relatively to part 17 and the jaws engage. Spring 12a acts as a return spring. In Fig. 11, driven part 17 is normally locked to driving part 18 by members 66-68 and locking member 65 in part 17 are engageable with cam projections 79 on anvil tube 77. Under drive, rockable rods 82 act on inclined surfaces 75 to move part 17 downwardly and expel balls 67 inwardly to disengage parts 17 and 18. Locking members 65 engage cams 79 and only when the members fall alongside the cams (on rotation) can they be forced outwardly thereby to allow the part 17 to move further and engage the jaws. Spring 83 returns the part 17 after impact. In Fig. 16, driven part 17 is axially locked to central tube 86 by members 92. Under drive, centrifugally acting balls 101 on inclined surface 98 force tube 86 and part 17 downwardly. At the same time springs 102,104 are compressed and balls 90 running in V-shaped grooves 87 (Fig. 19) on tube 86 and in triangular recesses 88 on part 17 run into the vertices. Locking members 92 are then displaced by anvil cam projections 100 which next engage projections 96 on tube 86 which is thus stopped and relative movement of balls, grooves and recesses 90, 87, 88 causes downward movement of the driven part 17 to cause engagement of the jaws 6 and 17. In the somewhat similar arrangement of Fig. 20, tube 86 is fixed on shaft 9 and a movable bush 118 is provided on the anvil 5. On axial movement of part 17, inclined portions 129 of jaws 6 engage with locking member 125 locking bush 118 to the anvil (Figs. 23-27). The members disengage from a projection (128) Figs. 27, 28, not shown, of the anvil as the bush is displaced by spring 120 whereafter cams 119 of bush 118 engage projection 96, see Fig. 16, on tube 86 which stops rotating and due to interaction of balls, grooves and recesses 87-90, as before, jaws 6 and 7 engage. In Fig. 30, hammer driving part 130 embraces driven part 131 and anvil 5. Parts 130, 131 are normally locked together by members 140. During drive, downward movement of rod 147, due to centrifugal flyweights 159 engaging flange 148, springs 164, 165 are compressed until projection 153 on pivoted lever 150 inside rod 147 engages a convex portion (157), Fig. 32, not shown, of anvil jaw 7. Pivoting of the lever causes ball 143 to disengage member 140 and the driven part 131 moves downwardly under the action of spring 164 and jaws 6, 7 engage. In Fig. 35, motor 8 comprises a central stator 172 on fixed axle 173 and a rotor 171 connected to driving part 174. Driven part 175 embraces an axially movable sleeve 178 on axle 173. In bores (179), Fig. 37, not shown, in the sleeve 178, balls (180) communicate via pushers (186) with locking members (185) in part 174. Under drive flyweight balls 194 move sleeve 178 and balls (180) and compress springs 195, 196. On engagement of the balls (180) with axial anvil projections (191), the balls, are forced into an annular groove (188) in the sleeve to act on pushers (186) to unlock members 185 and disengage driving and driven parts 174, 175. Under the action of spring 195, part 175 engages jaws 6 and 7. A switch 198 inside axle 173 cooperates with a surface 200 of sleeve 178 to disconnect electric power to motor 8 prior to impact.  In Fig. 40, hollow hammer driving part 204 includes annular member 205, driven part 206 carrying tubular member 212 having projections 214 and a shank 215. Anvil 5 supports axially movable rod 219 urged outwardly by spring 222. At a predetermined rotational speed, balls 230 act on inclined surfaces 211 of longitudinal projections 209 of part 206 which is displaced together with tubular member 212 and balls (233), Fig. 43, not shown, in V-shaped grooves and triangular recess, as in Figs. 16 and 20, disposed between member 212 and part 206 transmit rotary drive therebetween. Inclined surfaces, not shown, of jaws 6 act on pushers 225 to inwardly displace locking members 227 thereby releasing rod 219 from anvil 5. Projections 220, 214 engage, member 212 is halted and the ball-groove-recess arrangement causes axial movement of part 206 to engage jaws 6 and 7. In Fig. 1, axially fixed hammer 4 supports axially movable spring-loaded tubular member 241 locked by members 238. Axially displaceable anvil 5 embraces spindle 10 which supports bush 252 having axial projections 253 and mounted on axle 254. V-shaped grooves 258, triangular recesses 259 and balls 260 connect spindle 10 with bush 252. Under drive, locking members 238 disengage from member 241 by centrifugal action; projections 244 on member 241, and 253 on the bush 252 engage. The bush moves helically upward due to interaction of the balls, grooves and recesses, spring 256 is compressed, washer 257 engages locking projections 246 between spindle 10 and bush 252 and the anvil moves upwardly to engage the jaws. Fig. 45, not shown, is similar to Fig. 1 except that bush 252 has a shank (268), hammer 4 is composite with hollow parts (263) and annular member (264). Spring (271) absorbs shock. In Fig. 46, not shown, additional locking members (276) are provided between member 241 and member (264) and means in the form of balls (281) in grooves (282) prevent relative rotation but allow axial movement between members 241 and (264).