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EP-4197698-B1 - IMPACT DRIVER

EP4197698B1EP 4197698 B1EP4197698 B1EP 4197698B1EP-4197698-B1

Inventors

  • OPSITOS, ROBERT J.
  • PATEL, SANDIPKUMAR D.
  • NISAR, Hamza
  • PARKER, DYLAN

Dates

Publication Date
20260513
Application Date
20221215

Claims (14)

  1. A power tool (100) comprising: a housing (103), a motor assembly (105) disposed in the housing (103), an output shaft (109) at least partially received in and rotatable relative to the housing (103), and an impact assembly (107) operatively coupled with the motor assembly (105) and configured to be driven thereby, the impact assembly (107) comprising: a hammer (102) defining a hammer chamber (111) therein for receiving a fluid therein and an inwardly protruding impact member (114), the hammer (102) configured to be rotationally driven upon rotation of the motor assembly (105); an anvil (122) defining an anvil chamber (203) therein, the anvil (122) at least partially disposed in the hammer chamber (111) and configured to rotationally drive the output shaft (109); the anvil (122) comprising a body portion (113) configured to be rotatable relative to the hammer (102), and a reciprocating member (116) configured to selectively move radially outwardly relative to the body portion (113) to be impacted by the impact member (114) of the hammer (102) according to pressure of fluid in the anvil chamber (203) so that the hammer (102) imparts rotational movement to the body portion (113); characterised by an active valve (201) configured to control the discharge of the fluid from the anvil chamber (203) to the hammer chamber (111) so as to dampen the radial inward movement of the reciprocating member (116) to the body portion (113), the active valve (201) being configured to be variably open based on one or more physical characteristics of the fluid.
  2. The power tool (100) of claim 1 wherein it further comprises at least two foam members (140) within the hammer chamber (111), the foam members (140) being at least partially collapsible based upon a changing physical characteristic of the fluid during an operation of the impact assembly (107).
  3. A power tool (100) of any of the previous claims wherein the impact assembly (107) is configured to operate in an environment having an ambient temperature range between -30°C and 50°C without stall of the impact assembly (107).
  4. The power tool (100) of claim 1, wherein the anvil chamber (203) includes an inlet orifice (130) and an outlet orifice (132), and wherein the inlet orifice (130) and the outlet orifice (132) are configured to selectively provide fluid communication between the anvil chamber (203) and the hammer chamber (111).
  5. The power tool (100) of claim 4, wherein the active valve (201) is configured to be movable among a plurality of positions including a closed position and one or more at least partially open positions to control the discharge of the fluid from the anvil chamber (203) to the hammer chamber (111) via the outlet orifice (132).
  6. The power tool (100) of claim 5, further comprising a cam shaft (120) that is configured to be received within the anvil chamber (203) and configured to selectively seal the inlet orifice (130).
  7. The power tool (100) of claim 1, wherein the active valve (201) comprises a flapper valve wherein, preferably, the flapper valve comprises a flexible plate (175) that is configured to selectively cover and flex relative to an outlet orifice (132) in the anvil (203).
  8. The power tool (100) of claim 1, wherein the impact assembly (107) comprises an at least partially collapsible insert (140), preferably a foam insert, disposed inside the hammer chamber (111), wherein the at least partially collapsible insert (140) is configured to reduce in volume upon an increase in temperature or pressure of the fluid in the hammer chamber (111).
  9. The power tool (100) of claim 2, wherein each foam member (140) comprises closed-cell foam material.
  10. The power tool (100) of claim 2, wherein the foam members (140) are spaced from one another within the hammer (102).
  11. The power tool (100) of claim 10, wherein one of the foam members (140) is positioned at a first end portion of the hammer (102) and the other of the foam members (140) is positioned at an opposite second end portion of the hammer (102).
  12. The power tool (100) of claim 2, wherein the impact assembly (107) is configured to operate with the fluid in a temperature range between -30°C and 215°C without stall of the impact assembly (107).
  13. The power tool (100) of claim 2, wherein the foam members (140) fill at least approximately 65% of an interior volume of the hammer chamber (111) when uncompressed and/or at most approximately 45% of the interior volume of the hammer chamber (111) when compressed.
  14. The power tool (100) of claim 2, wherein the volume of each foam member (140) is compressible to approximately two-thirds of its uncompressed volume.

Description

The present patent application relates to impact drivers. Impact tools are configured to deliver rotational impacts to a workpiece at high speeds by storing energy in a rotating mass and transmitting it to an output shaft. The impact driver/tool generally includes a rotational impact mechanism/assembly, which has been used in power tools that are powered by either pneumatic or air-powered motors. The impact driver/tool may also be referred to as an oil pulse impact driver. More recently, this type of impact mechanism/assembly has been used in power tools powered by an electric motor. Two of these impact tools are described in U.S. Patent Application Publication No.: 2019/0232469 to Carlson et al. ("the '469 Publication") and U.S. Patent Application Publication No.: 2020/0047322 to Ito ("the '322 Publication"). FIG. 45 shows the impulse mechanism/assembly of the '469 Publication. FIGS. 46-48 also show various views of this prior art impact assembly. Referring to FIGS. 35-48, hammer cylinder and transmission assembly 1000 includes a hammer cylinder 1002, a planet carrier 1004 that is integral with the hammer cylinder 1002, three planet gears 1006, a carrier bearing 1008 and a ring gear 1010. The hammer cylinder 1002 has an integral planet carrier with three pins 1012 facing the ring gear 1010. These three pins 1012 attach to the three planet gears 1006, which couple with the ring gear 1010 and an output shaft of an electric motor. The carrier bearing 1008 connects to the back side of the hammer cylinder 1002 facing the ring gear 1010. The carrier bearing 1008 provides rotational support to the hammer cylinder 1002. The ring gear 1010 is received over the planet gears 1006 and the carrier bearing 1008 with the ring gear teeth meshed with the planet gear teeth. Since the planet gears 1006 are attached to the hammer cylinder 1002, the hammer cylinder 1002 rotates along with the planet gears 1006 once the electric motor is actuated. Inside the hammer cylinder 1002, there are two lugs 1014 that make contact with anvil blades 1016 every half rotation and a key slot 1018 that receives a rear end of a cam shaft 1020. The anvil assembly comprises an anvil shaft 1022, the cam shaft 1020, two balls 1024, and two blades or vanes 1016. The anvil shaft 1022 has an axial bore 1026 in its rear end that receives the cam shaft 1020 with a key 1028 of the cam shaft 1020 protruding from the rear end of the anvil shaft 1022. The cam shaft 1020 has cam surfaces 1029. The anvil shaft 1022 also has two oblong radial holes 1034 in communication with the axial bore 1026 that receive the balls 1024. The anvil shaft 1022 also includes blade holder 1053 and two slots 1036 that loosely receive the blades or vanes 1016 radially outward from the balls 1024. The anvil shaft 1022 also has two inlet holes 1030 and two outlet holes 1032 (one of each shown) for a viscous fluid. These holes 1030, 1032 are perpendicular to the radial ball holes 1034. The cam shaft 1029 has an oblong shape at its front end and the rectangular key 1028 at its rear end, which is received in the key slot 1018 in the hammer cylinder 1002 so that the cam shaft 1020 rotates together the hammer cylinder 1002. This allows the cam shaft 1020 to block or open the inlet hole 1030 and the ball hole 1034. The hammer cylinder 1002 and the cam shaft 1020 co-rotate, while the anvil shaft 1022 stays stationary for the most part. In one orientation, the cam shaft 1020 is able to block off the inlet holes 1030 while creating space for the balls 1024 to be pushed radially inwards, when the blades 1016 make contact with the hammer lugs 1014. When the blades 1016 make contact, the viscous fluid within the chamber provides resistances to the inward motion of the balls 1024. The viscous fluid acts as a damper and slows down the inward motion of the blades 1016. Between the time the lugs 1014 contact the blades 1016 and the blades 1016 skip over the lugs 1014, both the anvil shaft 1022 and the hammer cylinder 1002 are rotating together. Once the blades 1016 have passed over the lugs 1014, the cam shaft 1020 pushes the balls radially outward and prevents them from moving inwards. At this point, the inlet holes 1030 are open and the bore is in fluid communication with the hammer cylinder 1002. When anvil assembly is assembled in the hammer cylinder 1002, the anvil shaft 1022 extends partially from the open front end of the hammer cylinder 1002. An externally threaded cylinder cap 1038 is threadably attached to internal threads on the open end of the hammer cylinder 1002 to create a closed space within the hammer cylinder 1002 that is filled with the viscous fluid . A bladder 1040 that is filled with air or another gas is located within a cavity 1044 in the cylinder cap 1038. The air bladder 1040 accounts for the expansions of the working fluid in the enclosed space inside the hammer cylinder 1002. A disk 1042 is received over the anvil shaft 1022 located between the bladder 1040 and the hamm