1-25. (Canceled).
26. A method for producing a cable including at least one core comprising at least one transmissive element and at least one pair of coating layers arranged at a radially outer position with respect of said core, comprising the steps of:
a) depositing by co-extrusion around said core
1) at least one coating layer of polymeric material;
2) one coating layer of expanded polymeric material in contact with said at least one coating layer of polymeric material; and
b) maintaining a residual pressure not greater than the external pressure in a substantially annular interspace defined during said deposition step between said at least one coating layer of polymeric material and said one coating layer of expanded polymeric material,
wherein said steps a) and b) are carried out simultaneously.
27. The method according to claim 26, wherein said residual pressure is between about 5 kPa and about 90 kPa.
28. The method according to claim 27, wherein said residual pressure is between about 10 kPa and about 50 kPa.
29. The method according to claim 26, wherein said coating layer of expanded polymeric material is deposited by co-extrusion at a radially outer position with respect to said at least one coating layer of polymeric material.
30. The method according to claim 26 or 29, further comprising the step of depositing by extrusion around said at least one pair of coating layers an outer polymeric sheath of predetermined thickness.
31. The method according to claim 26, wherein the expandable material of said coating layer of expanded polymeric material expands during step a) of deposition by coextrusion.
32. The method according to claim 31, wherein said expandable material is selected from the group of polyethylene (PE), low density PE (LDPE), medium density PE (MDPE); high density PE (HDPE), linear low density PE (LLDPE); polypropylene (PP); ethylene-propylene rubber (EPR), ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM); natural rubber; butyl rubber; ethylene-vinyl acetate copolymer (EVA); polystyrene; ethyleneacrylate copolymer, ethylenemethyl acrylate (EMA), ethyleneethyl acrylate (EEA), ethylenebutyl acrylate (EBA); ethylenea-olefin copolymer; acrylonitrile-butadiene-styrene resin (ABS); halogenerated polymer, polyvinylchloride (PVC), polyurethane (PU); polyamide; aromatic polyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT); and derivatives and mixtures thereof.
33. The method according to claim 26, wherein said step of depositing by co-extrusion a coating layer of expanded polymeric material is carried out according to a draw down ratio (DDR) between about 0.3 and about 3.
34. The method according to claim 33, wherein said draw down ratio (DDR) is between about 0.4 and about 0.7.
35. The method according to claim 26, wherein said expanded polymeric material has an expansion degree between about 10% and about 200%.
36. The method according to claim 35, wherein said expansion degree is between about 50% and about 150%.
37. An extrusion apparatus for producing a cable including a core comprising at least one transmissive element and at least one pair of coating layers arranged at a radially outer position with respect of said core, comprising an extrusion head including:
a) a male die, at least one intermediate die and one female die coaxially mounted between each other around a longitudinal axis (E-E) substantially parallel to an advancing direction (A) of said core;
b) a longitudinal cavity intended for receiving said core defined in said male die;
c) at least one pair of feeding channels defined in said extrusion head and intended for depositing by co-extrusion, respectively, at least one coating layer of polymeric material and one coating layer of expanded polymeric material;
d) at least one suction channel intended for sucking the gases released during the expansion of said one coating layer of expanded polymeric material; and
e) a device for the formation of vacuum in fluid communication with said at least one suction channel.
38. An extrusion apparatus according to claim 37, wherein said first feeding channel is arranged at a radially inner position with respect of said second feeding channel.
39. The extrusion apparatus according to claim 37, wherein said first feeding channel is provided with an outlet opening arranged in proximity of said longitudinal cavity so as to deposit said coating layer of polymeric material in reciprocal contact with said core.
40. The extrusion apparatus according to claim 39, wherein said second feeding channel is provided with a respective outlet opening arranged in proximity of said outlet opening of said first feeding channel so as to deposit said coating layer of expanded polymeric material in reciprocal contact with said coating layer of polymeric material.
41. The extrusion apparatus according to claim 37, wherein said at least one suction channel is interposed between said first feeding channel and said second feeding channel.
42. The extrusion apparatus according to claim 37, wherein said first feeding channel is defined at least partly between said male die and said intermediate die.
43. The extrusion apparatus according to claim 37, wherein said second feeding channel is defined at least partly between said intermediate die and said female die.
44. The extrusion apparatus according to claim 37, further comprising a plurality of suction channels equally spaced with respect to said longitudinal axis (E-E).
45. The extrusion apparatus according to claim 44, wherein the geometrical centres of the cross-sections of said plurality of suction channels lie on the same circumference coaxial with respect of said longitudinal axis (E-E).
46. The extrusion apparatus according to claim 37, wherein said at least one suction channel is axially formed in said intermediate die.
47. The extrusion apparatus according to claim 37, wherein said extrusion head comprises an additional intermediate die and wherein said at least one suction channel is defined between said intermediate die and said additional intermediate die.
48. The extrusion apparatus according to claim 37, wherein said at least one suction channel has a substantially circular cross-section.
49. The extrusion apparatus according to claim 37, wherein said at least one suction channel has a substantially rectangular cross-section.
50. An extrusion apparatus for producing a cable including a core comprising at least one transmissive element, and at least one pair of coating layers arranged at a radially outer position with respect of said core comprising an extrusion
a) a male die, at least one intermediate die and one female die coaxially mounted between each other around a longitudinal axis (E-E) substantially parallel to an advancing direction (A) of said core;
b) a longitudinal cavity intended for receiving said core defined in said male die;
c) at least one pair of feeding channels defined in said extrusion head and intended for depositing by co-extrusion, respectively, at least one coating layer of polymeric material and one coating layer of expanded polymeric material; and
d) a plurality of suction channels intended for sucking the gases released during the expansion of said one coating layer of expanded polymeric material, said suction channels being defined in said extrusion head between said feeding channels.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A valve timing control system for an internal combustion engine having a crankshaft, an intake valve, an exhaust valve, an intake cam for opening and closing said intake valve, and an exhaust cam for opening and closing said exhaust valve, the valve timing control system controlling valve timing of at least one of said intake valve and said exhaust valve by changing a cam phase which is a phase of at least one of said intake cam and said exhaust cam, relative to said crankshaft,
the valve timing control system comprising:
actual cam phase-detecting means for detecting said cam phase as an actual cam phase:
a cam phase change mechanism for changing said cam phase:
operating condition-detecting means for detecting operating conditions of said engine;
fuel cut-off determination means for determining whether or not fuel cut-off is being carried out for cutting off supply of fuel to said engine;
desired cam phase-setting means for setting a desired cam phase according to said detected operating conditions of said engine, and fixing said desired cam phase at a constant value during said fuel cut-off;
cam phase control means for controlling said cam phase change mechanism such that said cam phase change mechanism causes said cam phase to become equal to said desired cam phase, and holds said cam phase at and after a predetermined timing during said fuel cut-off; and
actual cam phase deviation calculation means for calculating an amount of deviation of said actual cam phase based on a plurality of values of said actual cam phase detected at and after said predetermined timing during said fuel cut-off, and said constant value of said desired cam phase.
2. A valve timing control system according to claim 1, further including:
actual cam phase-integrating means for integrating an amount of change in said actual cam phase before said fuel cut-off to obtain an integrated value; and
calculation-permitting means for permitting said actual cam phase deviation calculation means to calculate said amount of deviation of said actual cam phase when said integrated value is equal to or larger than a predetermined value.
3. A valve timing control system according to claim 1, further including:
follow-up delay determination means for determining based on a difference between said desired cam phase and said actual cam phase whether or not there occurs a follow-up delay of said actual cam phase with respect to said desired cam phase; and
second calculation-permitting means for permitting said actual cam phase deviation calculation means to calculate said amount of deviation of said actual cam phase when it is determined by said follow-up delay determination means that there does not occurs said follow-up delay.
4. A valve timing control system according to claim 2, further including:
follow-up delay determination means for determining based on a difference between said desired cam phase and said actual cam phase whether or not there occurs a follow-up delay of said actual cam phase with respect to said desired cam phase; and
second calculation-permitting means for permitting said actual cam phase deviation calculation means to calculate said amount of deviation of said actual cam phase when it is determined by said follow-up delay determination means that there does not occurs said follow-up delay.