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Concentric camshaft arrangement

a technology of concentric camshafts and camshaft plates, which is applied in the direction of engine components, machines/engines, auxilaries, etc., can solve the problem of no longer being able to provide an oil feed via one or more of the hydrodynamic bearing journals of the concentric camsha

Inactive Publication Date: 2015-07-09
MECHADYNE INT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to an improved concentric camshaft arrangement that solves problems associated with existing arrangements. The arrangement comprises an inner shaft, an outer tube, a set of lobes, a roller bearing, and an oil feed. The oil feed is created by a larger radial clearance between the outer tube and the cylinder head than there is between the roller bearing and the cylinder head. This arrangement supports the camshaft with the roller bearing while also allowing for better lubrication of the bearing.

Problems solved by technology

However, the use of roller bearings presents a problem in that the bearing journals supporting the movable cam lobes of the second set on the outer tube of a concentric camshaft require an oil feed to reduce friction and prevent wear between the moving cam lobes and the camshaft outer tube.
If roller bearings are used to support the loads of known concentric camshafts, providing an oil feed via one or more of the hydrodynamic bearing journals of the concentric camshaft is no longer possible and an alternative oil feed is required to lubricate the journal bearings of the second set of cam lobes.

Method used

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first embodiment

[0024]Referring to FIG. 2, a concentric camshaft arrangement 100, according to the present invention, comprises a concentric camshaft 110 having an inner shaft 112 and an outer tube 114. A first set of cams 116 is fixed for rotation with the outer tube 114 and a second set of cams 118 is rotatably mounted on bearing journals on the outer tube 114 and connected to the inner shaft 112, by pins 119, for rotation therewith.

[0025]The concentric camshaft 110 is co-axially arranged within a bore 122 of the cylinder head 121, such that a predefined clearance exists between the bore 122 and the external surface of the outer tube 114.

[0026]A camshaft oil feed 120 is formed in a portion of the cylinder head 121. The camshaft oil feed 120 extends into a groove 126, which is formed in and extends around the circumference of the outer surface of the outer tube 114. A plurality of circumferentially spaced apart radial holes 124 extend radially inwards from the groove 126 through the wall of the ou...

second embodiment

[0038]The embodiment shown in FIG. 3 differs from that of FIG. 2 in that, instead of having an oil groove (126 in FIG. 2) disposed around the circumference of the outer tube (114 in FIG. 2), the second embodiment has a separately formed oil feed sleeve 256 that is fixed to, so as to rotate with and effectively form part of the outer tube 214. An oil groove 226 is disposed around the external circumference of the oil feed sleeve 256 and is arranged to receive oil from an oil feed 220, disposed in a portion of the cylinder head 221. The oil groove 226 communicates with a plurality of circumferentially spaced apart radial holes 258, which extend through the wall of the oil feed sleeve 256.

[0039]The sleeve radial holes 258 are axially aligned with the radial holes 224 disposed in the outer tube 214, which, as previously described, provide oil into the lubrication cavity 228. The oil then exits the lubrication cavity 228 through pin slots 230, formed in the outer tube 214, directly under...

third embodiment

[0048]the invention, as shown in FIG. 4, comprises a second oil feed 364 disposed in a portion of the cylinder head 321. The second oil feed 364 serves to provide a pressurised oil supply to a camshaft phaser oil supply cavity 366 for use with a phaser having an integral spool valve for controlling the phase of the camshaft.

[0049]A second oil groove 368 is disposed around the external circumference of the oil feed sleeve 356 and arranged to receive oil from the second oil feed 364. The second oil groove 368 communicates with a plurality of circumferentially spaced apart second radial holes 370, which extend through the wall of the oil feed sleeve 356.

[0050]The second sleeve radial holes 370 are aligned with a plurality of circumferentially spaced apart second outer tube radial holes 373, which are in fluid communication with the phaser oil supply cavity 366 to provide pressurised oil from the second oil feed 364 thereto.

[0051]A fifth seal 372 is disposed in a seal groove extending c...

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Abstract

A concentric camshaft arrangement comprises an inner shaft, an outer tube concentrically arranged around the inner shaft and rotatably supported in a cylinder head. A first set of lobes is fixed for rotation with the outer tube and a second set of lobes is rotatably supported by bearing journals on the outer tube and connected for rotation with the inner shaft. The outer tube is supported in the cylinder head by means of a roller bearing and an oil feed is provided for supplying oil for lubricating the bearing journals of the second set of cam lobes. At least part of the oil feed is defined by a radial clearance between the outer surface and an inner surface of the cylinder head that is sealed at its axial ends, the radial clearance being larger than any radial clearance at the roller bearing so that loads on the camshaft are supported at least predominantly by the roller bearing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is the §371 National Stage Entry of International Application Serial No. PCT / IB2013 / 055764, filed on Jul. 12, 2013, which claims the benefit of United Kingdom Patent Application Serial No. GB 1212683.5, filed on Jul. 12, 2012.FIELD OF THE INVENTION[0002]The present invention relates to concentric camshaft arrangements and particularly to concentric camshaft arrangements that use roller bearings to support the loads of the camshaft.BACKGROUND OF THE INVENTION[0003]Known concentric camshafts have an inner shaft and an outer tube that are rotatable relative to one another. A first set of cams is fixed for rotation with the outer tube and a second set of cams is mounted on bearing journals on the outer tube and connected for rotation with the inner shaft by means of pins that extend through circumferentially elongated slots in the outer tube.[0004]Such known concentric camshafts are typically supported in the engine using hyd...

Claims

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Application Information

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IPC IPC(8): F01M9/10F01L1/344F01L1/047
CPCF01M9/102F01L1/047F01L2001/34423F01L2001/0473F01L2001/0476F01L1/3442F01L1/34413F01L2810/02Y10T74/2101F01L1/344
Inventor METHLEY, IANLAWRENCE, NICHOLAS JAMES
Owner MECHADYNE INT