Power tool comprising a hydraulic pulse unit
Provided is an impulse tool including a motor, an output shaft, and a hydraulic pulse unit including an inertia drive member connected to the motor and rotatable about a rotation axis, an oil chamber enclosed in the inertia drive member and an impulse generating means arranged to transfer intermittently kinetic energy to the output shaft. The inertia drive member further includes an end piece having a transverse wall and a disc shaped element arranged to at least partly delimit a receiving space in fluid communication with the oil chamber. Formed between the disc shaped element and the transverse wall and a compressible insert arranged in fluidic communication with the receiving space. The compressible insert includes a foam body including a closed cell foam, and wherein the compressible insert is arranged in an insert space formed in the end piece.
1 . An impulse tool comprising a motor, an output shaft, and a hydraulic pulse unit including an inertia drive member connected to the motor and rotatable about a rotation axis, an oil chamber enclosed in the inertia drive member and an impulse generating means arranged to transfer intermittently kinetic energy to the output shaft, wherein the inertia drive member further comprises an end piece having a transverse wall,
said impulse tool further comprising a disc shaped separator element arranged to at least partly delimit a receiving space in fluid communication with said oil chamber by means of an opening provided in the disc shaped separator element through which oil may flow between the oil chamber and the receiving space, the receiving space being formed between the disc shaped separator element and the transverse wall,
wherein said impulse tool further comprises a compressible insert arranged in fluidic communication with said receiving space,
wherein the compressible insert comprises a foam body comprising a closed cell foam, and
wherein said compressible insert is arranged in an insert space formed in said end piece, wherein said insert space is arranged adjacent to said receiving space, wherein said insert space extends between said receiving space and an oil inlet formed in said end piece, and wherein an oil channel is formed in said compressible insert, said oil channel forming a fluid path fluidly connecting said receiving space and said oil inlet to allow a flow of oil to pass through a portion of said compressible insert, wherein the oil inlet is externally accessible, and wherein said oil channel is sized to receive oil from an external source via the oil inlet and to thereby fill the receiving space with oil.
2 . The impulse tool according to claim 1 , wherein said insert space extends in an axial direction from said receiving space over at least two-thirds of the length of said end piece.
3 . The impulse tool according to claim 1 , wherein an outer boundary surface of the compressible insert and the insert space are congruent, such that the compressible insert in an uncompressed state fills the whole insert space.
4 . The impulse tool according to claim 1 , wherein said oil channel is an oil channel for filling said pulse unit with oil, the oil channel extending along a center axis of said compressible insert.
5 . The impulse tool according to claim 1 , wherein said oil channel is an oil channel for filling said pulse unit with oil, the oil channel extending in a direction perpendicular to a center axis of said compressible insert.
6 . The impulse tool according to claim 1 , wherein the compressible insert is rotationally symmetric with respect to a center axis of the pulse unit and wherein a radius of said compressible insert is less than or equal to half of a radius of said end piece along the length of the insert chamber.
7 . The impulse tool according to claim 6 , wherein at least one of said radius of said compressible insert and said varying radius of said end piece is/are varying along the length of the insert chamber.
8 . The impulse tool according to claim 1 , wherein the volume of the insert lies in the range 10-30% of a combined total volume of said oil chamber and said receiving space.
9 . The impulse tool according to claim 8 , wherein the volume of the insert lies in the range 10-25% of said combined total volume.
10 . The impulse tool according to claim 8 , wherein the volume of the insert lies in the range 10-20% of said combined total volume.
11 . The impulse tool according to claim 8 , wherein the volume of the insert lies in the range 10-15% of said combined total volume.
12 . The impulse tool according to claim 1 , wherein said closed cell foam is a foam material which can withstand 20-50% compression without permanent deformation.
13 . The impulse tool according to claim 1 , wherein the cell diameter of the closed cell foam lies in the range 0.15-0.35 mm.
14 . The impulse tool according to claim 1 , wherein the gas fraction of the cell foam lies in the range 85-99%.
15 . The impulse tool according to claim 1 , wherein the closed cell foam is made of polyvinyl fluoride.
16 . The impulse tool according to claim 1 , wherein said closed cell foam is a foam material which can withstand 20-30% compression without permanent deformation.
17 . The impulse tool according to claim 1 , wherein said closed cell foam is a foam material which can withstand 22-27% compression without permanent deformation.
18 . The impulse tool according to claim 1 , wherein the cell diameter of the closed cell foam lies in the range 0.2-0.3 mm.
19 . The impulse tool according to claim 1 , wherein the cell diameter of the closed cell foam lies in the range 0.25-0.28 mm.