EP3683412A1 - Arbre à cames concentrique - Google Patents

Arbre à cames concentrique Download PDF

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Publication number
EP3683412A1
EP3683412A1 EP19152736.5A EP19152736A EP3683412A1 EP 3683412 A1 EP3683412 A1 EP 3683412A1 EP 19152736 A EP19152736 A EP 19152736A EP 3683412 A1 EP3683412 A1 EP 3683412A1
Authority
EP
European Patent Office
Prior art keywords
camshaft
inner tube
tube
drive member
cam lobes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19152736.5A
Other languages
German (de)
English (en)
Inventor
Owen Fernández-Oxby
Timothy Mark Lancefield
Ian Methley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mechadyne International Ltd
Original Assignee
Mechadyne International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mechadyne International Ltd filed Critical Mechadyne International Ltd
Priority to EP19152736.5A priority Critical patent/EP3683412A1/fr
Priority to PCT/IB2019/061302 priority patent/WO2020152528A1/fr
Publication of EP3683412A1 publication Critical patent/EP3683412A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/34413—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using composite camshafts, e.g. with cams being able to move relative to the camshaft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L2001/0471—Assembled camshafts
    • F01L2001/0473—Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L2001/0475—Hollow camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F01L2303/01—Tools for producing, mounting or adjusting, e.g. some part of the distribution

Definitions

  • the invention relates to a valvetrain system for an internal combustion engine, and, in particular, to an adjustable camshaft, also known as a concentric camshaft, having two groups of cam lobes which can be phased relative to each other.
  • an adjustable camshaft also known as a concentric camshaft
  • the concentric camshaft allows the phase of one. or both. of the two groups of lobes to be controlled independently relative to the phase of the engine crankshaft. In a single camshaft engine, this could allow independent control of intake and/or exhaust valve timing.
  • Concentric camshafts are well known that allow the relative timing of two sets of cam lobes to be adjusted, and typically these are comprised of an outer tube having a first set of cam lobes fixed to its outer surface and a second set of cam lobes mounted for rotation about the outer surface of the tube.
  • Each of the cam lobes of the second set is connected by a drive member, for rotation with an inner shaft passing through the bore of the outer tube.
  • Each drive member passes with clearance through a circumferentially elongated slot in the wall of the outer tube, to allow rotation of the second set of cam lobes through a limited angle when the inner shaft is rotated relative to the outer tube.
  • the inner shaft from a hollow tube, thereby saving mass with only a small reduction in stiffness. Furthermore, the use of an inner tube, in place of an inner shaft, opens the possibility of different constructions of the drive members for connecting the inner tube with the second set of cam lobes.
  • the inner tube must be rigidly connectable to such elements as the phaser and a timing wheel, a task commonly performed by a threaded fastener.
  • the requirement for an internal thread restricts the mass reductions that can be achieved by placing a limit on the maximum allowable inner tube internal diameter.
  • the alternative of manufacturing a tube with multiple inner diameters would involve expensive machining.
  • the invention therefore seeks to provide a practical and cost-effective method of manufacture and design of a concentric camshaft that employs an inner tube in place of an inner shaft.
  • Figures 1 and 2 illustrate the construction of a concentric camshaft of a first embodiment, the camshaft comprising an outer tube 10 and an inner tube 12.
  • a first set of cam lobes 14, a front camshaft bearing 16, and additional camshaft bearings 18 for supporting the camshaft in an engine are fixed to the outer surface of the outer tube 10.
  • a second set of cam lobes 20 and, optionally, a camshaft timing wheel 22 are attached for rotation with the inner tube 12.
  • a camshaft phasing system 24 (shown in Figure 2 but not in Figure 1 ) is attached to the inner tube 12 via a fastener 26, the phasing system 24 being able to transfer torque through axial end of the inner tube 12.
  • the inner tube 12 may protrude from the axial end of the outer tube 10 in order to engage the phasing system 24.
  • the second set of cam lobes 20, the outer tube 10 and the inner tube 12 each feature a corresponding radial through hole that, when the camshaft is assembled, line up with one another to allow a dowel-like drive member 40 to be inserted.
  • the hole in the outer tube 10 is slotted around part of its circumference, enabling the inner tube 12, the second set of cam lobes 20 and the drive member 40 to rotate together relative to the outer tube 10.
  • the camshaft assembly may include a collar 30 fitted onto the outer surface of the inner tube 12 to contact an axial end of the outer tube 10, the collar 30 may serve to locate the inner tube 12 axially within the outer tube 10, or as a seal to prevent the egress of oil.
  • the assembly may also include a plug 32 at the axial end of the outer tube 10 opposite to that of the phasing system 24, the plug 32 also serving as a seal to prevent egress of oil.
  • the plug 32 may be push fit or may be threaded to engage threads in the inner surface of the outer tube 10.
  • the formation 28 is just one way of transmitting torque to the inner tube and alternative possibilities include the use of one or more keyways, a splined connection or a friction drive.
  • a region of the inner tube 12, disposed within the circle B in Figure 2 is plastically deformed to reduce both its inner and outer diameter, allowing the inner surface of the inner tube 12 to be tapped to provide a thread to engage the fastener 26.
  • Plastic deformation of the inner tube 12 may be accomplished by swaging, application of heat and radial compression, hydroforming or any other suitable method that relies on deformation, as opposed to removal of material, to reduce the outer diameter of the inner tube.
  • the second embodiment will feature reference numerals in the one hundred series, i.e. preceded by a '1'
  • the third embodiment will feature reference numerals in the two hundred series, i.e. preceded by a '2', and so on.
  • a second embodiment of the invention is shown in figure 3 , wherein the camshaft comprises an inner tube 112 which is deformed at one axial end.
  • the inner tube 112 is threaded in the deformed region and another component is attached to the inner tube 112 through use of a fastener 134.
  • the component fastened to the inner tube in this embodiment is an assembly comprising a camshaft bearing 118 and a timing wheel 122.
  • the inner diameter of the camshaft bearing 118 is in tight clearance to the outer diameter of the outer tube 110, thereby having a bearing surface to the outer tube 110.
  • the timing wheel 122 is supported concentrically to the outer tube 110 via its connection to the camshaft bearing 118.
  • An intermediary component in the form of an end plate may be used, the end plate being welded to the bearing 118 and fastened to the inner tube 112.
  • the camshaft bearing 118 may contain oil vents as shown in figure 3 in the form of axial through holes, or similar, to avoid over-pressuring of a seal fitted in the bearing bore.
  • Figure 3 also shows an alternative arrangement for connecting the phaser (not shown) for rotation with the second set of cam lobes 120, wherein a drive coupling 138 features a threaded hole 139 for securing the phaser, through use of a fastener.
  • the inner tube 112 and drive coupling 138 are connected by a drive member 140 in the form of a dowel pin, which also forms the drive connection for one lobe from the second set of cam lobes 120.
  • the drive coupling 138 may be connected to the bore of the inner tube 112 through an interference fit.
  • Figure 4 shows a third embodiment in which the front camshaft bearing 216 features channels 217 for fluid communication to the phaser.
  • a hole in the outer tube 210 is arranged such that pressurized oil can enter a cavity 242 between the inner surface of the outer tube 210 and the outer surface of the deformed portion of the inner tube 212.
  • the oil enters the cavity 242 between the inner shaft 212 and the outer shaft 210 such that there is no flow restriction.
  • a hole 244 is provided in the inner tube 212 to allow oil to flow between two cavities 242, 243, one between the inner tube 212 and outer tube 210, and another between the fastener 216 and the inner tube 212.
  • the hole 244 in the inner tube 212 allows the pressurized oil to flow through the cavity 243 between the inner tube 212 and the fastener 216 into the phaser.
  • Figure 5 to Figure 16 show different designs of the drive member connecting cam lobes for rotation with the inner tube. All these figures show different possible constructions of the detail shown with the circle C in Figure 2 .
  • Figure 5 illustrates a fourth embodiment comprising a hollow drive member 340.
  • the inner and outer diameters of the drive member 340 are substantially constant along its length, the outer diameter of the drive member 340 being slightly smaller than the diameter of the hole.
  • the drive member 340 is plastically deformed such that it is in interference with the inner edge of the hole in the inner tube 312.
  • the central portion of the drive member 340 that lies between the holes in the inner tube 312 is of a greater diameter than the holes in the inner tube 312, thereby further securing the drive member 340 in the axial direction.
  • one method of deforming the drive member 340 is hydroforming.
  • Hydroforming comprises the steps of pumping a fluid, such as water or oil, into the bore of the drive member 340 at extreme pressures to force the material to plastically deform locally.
  • the fluid is directed into the hollow cavity by punches 346 which contain sealing features to retain and direct the fluid into the required area.
  • the length of the section of the punches that sit inside the drive member is chosen so that the fluid pressure cannot deform the drive member in the region of the outer tube and stop any relative rotation of the inner and outer tubes.
  • An alternative method to secure the drive member 440 is staking, as illustrated in Figures 6 and 7 .
  • the staking process involves passing a hardened tool through a radial pocket 448 in the drive member 440.
  • the shape of the pocket 448 and the shape of the tool are designed such that when the tool passes through the pocket 448, the drive member 440 expands radially, thereby being secured inside the inner tube 412.
  • Figures 8 and 9 show a riveting process to cause an interference fit between the drive member 540 and the inner tube 512.
  • the process includes forcing a mandrel 550 through the bore of the drive member 540, the mandrel 550 comprising a shaft of a smaller diameter than the bore of the drive member 540 and a spherical head of a greater diameter than the bore of the drive member 540.
  • the mandrel 550 may be inserted into the drive member 540 before assembly into the inner tube 512.
  • the hole in the drive member 540 may be a plain through hole or a counterbore hole, with the counterbore diameter being greater than the diameter of the spherical head of the mandrel 550, depending on whether an interference fit is desired between the drive member 540 and the cam lobe 520.
  • the hole may feature a counterbore at both axial ends of the drive member 540.
  • FIG. 10 and 11 it is possible to use more than one drive member to secure the second set of cam lobes for rotation with the inner tube.
  • One such embodiment uses the riveting technique already disclosed, but with two drive members 640a, 640b.
  • the mandrels 650a, 650b are assembled to the individual drive members 640a, 640b before insertion into the inner tube 612 and may be passed through the holes of the drive members 640a, 640b individually or simultaneously.
  • the holes in the drive members 640a, 640b may be counterbored as in the previous embodiment.
  • a further embodiment, as illustrated in Figure 12 uses the insertion of ball bearings 752a to plastically deform the drive member 740 in a precise location, such as where the drive member 740 is to contact the inner tube 712. If it is desired for the drive member 740 to also contact the cam lobe 720, then further ball bearings 752b may be used as shown in Figure 13 . Although Figure 13 shows that all ball bearings 752a, 752b are the same diameter, the outer ball bearings 752b may be of a larger diameter to secure the drive member 740 to the cam lobe 720.
  • the drive member 740 may feature a counterbore hole and no outer ball bearings 752b, as shown in Figure 12 .
  • the ball bearings 752a, 752b may remain inside the drive member 740 after the assembly process, being retained by the interference generated by their insertion.
  • FIG 14 shows a drive member 840 consisting of a coiled sheet of material in the form of a spring, commonly known as a spring pin or a rolled pin.
  • the spring pin 840 diameter in its relaxed state is greater than the hole in the inner shaft 812.
  • FIGS 15 and 16 show a drive connection method comprising a fastened assembly of two drive members 940a, 940b, each featuring a dowel-like portion and a threaded portion, and a coupling piece 954 with an axial hole, at least a portion of which is threaded.
  • the coupling piece 954 may have features (not shown) which allow it to be correctly oriented both axially and rotationally in the inner tube 912 so that it can accept the drive members 940a, 940b during assembly.
  • the coupling piece 954 is inserted into the bore of the inner tube 912 and the two drive members 940a, 940b are inserted through the holes in the cam lobe 920 and inner tube 912 with a clearance or transition fit, and then fastened into the coupling piece 954 thereby securing them and the cam lobe 920 for rotation with the inner tube 912.
  • the two drive members 940a, 940b may accept any means for tightening and loosening them, including Allen keys, sockets, or torx, flat-head, Philips and Posi drive drill bits and screwdrivers.
  • machining a counterbore into the axial end of a drive member may be carried out on any embodiment above in order to change the pressure distribution characteristics of the drive member acting on the outer tube and cam lobe.
  • Some embodiments described and depicted as one drive member may instead feature a drive member assembly comprising two smaller drive members, each drive member disposed in a hole in the inner tube and a corresponding hole in the outer tube and second set of cam lobes.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
EP19152736.5A 2019-01-21 2019-01-21 Arbre à cames concentrique Withdrawn EP3683412A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19152736.5A EP3683412A1 (fr) 2019-01-21 2019-01-21 Arbre à cames concentrique
PCT/IB2019/061302 WO2020152528A1 (fr) 2019-01-21 2019-12-23 Arbre à cames concentrique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19152736.5A EP3683412A1 (fr) 2019-01-21 2019-01-21 Arbre à cames concentrique

Publications (1)

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EP3683412A1 true EP3683412A1 (fr) 2020-07-22

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EP19152736.5A Withdrawn EP3683412A1 (fr) 2019-01-21 2019-01-21 Arbre à cames concentrique

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EP (1) EP3683412A1 (fr)
WO (1) WO2020152528A1 (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008023066A1 (de) * 2008-05-09 2009-11-12 Hydraulik-Ring Gmbh Nockenwellenverstellung mit trockener Lauffläche
US20100170458A1 (en) * 2007-07-02 2010-07-08 Borgwarner Inc. Concentric cam with check valves in the spool for a phaser
US20100223771A1 (en) * 2009-03-03 2010-09-09 Gm Global Technology Operations, Inc. Concentric camshaft and method of assembly
US20140283773A1 (en) * 2011-12-10 2014-09-25 Volkswagen Aktiengesellschaft Adjustable camshaft drive
EP3000995A1 (fr) * 2014-09-29 2016-03-30 Mechadyne International Limited Ensemble roue de synchronisation pour un arbre à cames concentrique
EP3176390A1 (fr) * 2015-12-02 2017-06-07 Mahle International GmbH Arbre à cames réglable
US20170183981A1 (en) * 2014-05-27 2017-06-29 Thyssenkrupp Presta Teccenter Ag Variable valve timing camshaft with improved oil transfer between inner and outer shafts

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100170458A1 (en) * 2007-07-02 2010-07-08 Borgwarner Inc. Concentric cam with check valves in the spool for a phaser
DE102008023066A1 (de) * 2008-05-09 2009-11-12 Hydraulik-Ring Gmbh Nockenwellenverstellung mit trockener Lauffläche
US20100223771A1 (en) * 2009-03-03 2010-09-09 Gm Global Technology Operations, Inc. Concentric camshaft and method of assembly
US20140283773A1 (en) * 2011-12-10 2014-09-25 Volkswagen Aktiengesellschaft Adjustable camshaft drive
US20170183981A1 (en) * 2014-05-27 2017-06-29 Thyssenkrupp Presta Teccenter Ag Variable valve timing camshaft with improved oil transfer between inner and outer shafts
EP3000995A1 (fr) * 2014-09-29 2016-03-30 Mechadyne International Limited Ensemble roue de synchronisation pour un arbre à cames concentrique
EP3176390A1 (fr) * 2015-12-02 2017-06-07 Mahle International GmbH Arbre à cames réglable

Also Published As

Publication number Publication date
WO2020152528A1 (fr) 2020-07-30

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