U.S. patent application number 11/676471 was filed with the patent office on 2008-08-21 for mounting of an scp camshaft on an engine.
This patent application is currently assigned to MECHADYNE PLC. Invention is credited to Timothy Mark Lancefield, Nicholas James Lawrence, Richard Alwyn Owen.
Application Number | 20080196681 11/676471 |
Document ID | / |
Family ID | 39705594 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080196681 |
Kind Code |
A1 |
Lancefield; Timothy Mark ;
et al. |
August 21, 2008 |
MOUNTING OF AN SCP CAMSHAFT ON AN ENGINE
Abstract
A method disclosed for mounting a camshaft and a phaser on an
engine, the camshaft being an SCP camshaft formed of concentric
inner and outer rotary members each fast in rotation with a
respective one of two groups of cams and the phaser enabling the
phase of at least one of the rotary members of the camshaft to be
varied dynamically relative to the phase of the engine crankshaft
and the other rotary member. The method comprises first securing
the phaser 30 to one end of the camshaft 10, then mounting the
camshaft and phaser as a sub-assembly to the engine, and
subsequently securing to the engine an abutment 40 for limiting the
axial displacement of the camshaft relative to the engine.
Inventors: |
Lancefield; Timothy Mark;
(Shipston on Stour, GB) ; Lawrence; Nicholas James;
(Buckingham, GB) ; Owen; Richard Alwyn; (Banbury,
GB) |
Correspondence
Address: |
SMITH-HILL AND BEDELL, P.C.
16100 NW CORNELL ROAD, SUITE 220
BEAVERTON
OR
97006
US
|
Assignee: |
MECHADYNE PLC
Kirtlington
GB
|
Family ID: |
39705594 |
Appl. No.: |
11/676471 |
Filed: |
February 19, 2007 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 2001/0473 20130101;
F01L 2001/0476 20130101; F01L 2303/00 20200501; F01L 1/34413
20130101; F01L 2001/0475 20130101 |
Class at
Publication: |
123/90.17 |
International
Class: |
F01L 1/047 20060101
F01L001/047 |
Claims
1. A method of mounting a camshaft and a phaser on an engine, the
camshaft being an SCP camshaft formed of concentric inner and outer
rotary members each fast in rotation with a respective one of two
groups of cams and the phaser enabling the phase of at least one of
the rotary members of the camshaft to be varied dynamically
relative to the phase of the engine crankshaft and the other rotary
member, which method comprises securing the phaser to one end of
the camshaft, mounting the camshaft and phaser as a sub-assembly to
the engine by sliding the camshaft axially from the front end of
the engine into bearing blocks in the engine, and subsequently
securing to the engine an abutment for limiting the axial
displacement of the camshaft relative to the engine.
2. A method as claimed in claim 1, wherein the abutment is formed
as a thrust plate integrated as part of the camshaft and phaser
sub-assembly.
3. A method as claimed in claim 1, wherein the abutment comprises a
thrust plate located on the opposite end of the camshaft from the
phaser.
4. A method as claimed in claim 1, wherein the abutment is
constituted by an engine front cover contacting the front face of
the phaser.
5. (canceled)
6. An engine having a crankshaft, a camshaft formed of concentric
inner and outer rotary members each fast in rotation with a
respective one of two groups of cams, bearing Journals on the
camshaft having a larger radius than the largest cam lobe radius to
enable the camshaft to slide axially from the front end of the
engine into bearing blocks in the engine, a phaser mounted on the
camshaft to enable the phase of at least one of the rotary members
to be varied dynamically relative to the phase of the crankshaft
and the other rotary member, and a thrust control member capable of
being secured to the engine after the camshaft and phaser have been
fitted as a sub-assembly to the cylinder block or cylinder head of
the engine.
7. An engine as claimed in claim 6, wherein a thrust plate serves
to control the axial position of the camshaft relative to the
engine and is Located on the opposite end of the camshaft from the
phaser.
8. An engine as claimed in claim 6, wherein the axial position of
the camshaft is defined by the rear of a cylinder block or cylinder
head and a surface of a cover fitted to the rear of the engine.
9. An engine as claimed in claim 6, wherein the axial position of
the camshaft is determined in use by the phaser coming into contact
with a front face of a cylinder block or a cylinder head and a
surface of a cover fitted to the front of the engine and overlying
the phaser.
10. An engine as claimed in claim 9, wherein the front cover is
fitted with an adjustable thrust member to allow the axial
clearance of the camshaft to be set upon assembly of the
engine.
11. An engine as claimed in claim 10, wherein the adjustable plate
serves additionally to transmit oil to the phaser.
12. An engine as claimed in claim 6, wherein the axial clearance
within the camshaft assembly and the phaser is controlled by a
single shim.
13. An engine as claimed in claims claim 12, wherein the axial
clearance adjusting shim acts as the thrust plate.
Description
FIELD OF THE INVENTION
[0001] The invention relates to the mounting on an engine of an SCP
camshaft formed of concentric inner and outer rotary members each
fast in rotation with a respective one of two groups of cams and a
phaser for enabling the phase of at least one of the rotary members
to be varied dynamically relative to the phase of the crankshaft
and the other rotary member. This type of camshaft is termed an SCP
(single cam phaser) camshaft because it allows the timing of two
groups of cams to be varied in relation to one another using a
single camshaft by relative rotation of the camshaft tube and the
inner drive shaft.
[0002] The invention is particularly applicable to an SCP camshaft
that has large camshaft bearings and is assembled to the engine
from one end of a bearing bore in the cylinder block or cylinder
head. Such applications generally utilize a thrust plate to control
the axial position of the camshaft within the cylinder head or
cylinder block.
BACKGROUND OF THE INVENTION
[0003] Many different designs of SCP camshaft are known from the
prior art and each requires a method for driving the camshaft from
the crankshaft and for introducing a phase shift in the timing of
the camshaft tube and/or drive shaft. Generally the phaser requires
two driving connections to the SCP camshaft, one to drive the
camshaft tube and one to drive the inner shaft. The driving
connections can be particularly difficult to design when the
camshaft thrust plate is located between the phasing system and the
front of the camshaft. Because of this, the phaser conventionally
needs to be removed in order to access the fixings securing the
thrust plate to the front of the cylinder head or block.
OBJECT OF THE INVENTION
[0004] The aim of the present invention is therefore to simplify
the mounting of an SCP camshaft on an engine.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the invention, there is provided
a method of mounting a camshaft and a phaser on an engine, the
camshaft being an SCP camshaft formed of concentric inner and outer
rotary members each fast in rotation with a respective one of two
groups of cams and the phaser enabling the phase of at least one of
the rotary members of the camshaft to be varied dynamically
relative to the phase of the engine crankshaft and the other rotary
member, which method comprises securing the phaser to one end of
the camshaft, mounting the camshaft and phaser as a sub-assembly to
the engine, and subsequently securing to the engine an abutment for
limiting the axial displacement of the camshaft relative to the
engine.
[0006] In a second aspect of the invention, there is provided an
engine having a crankshaft, a camshaft formed of concentric inner
and outer rotary members each fast in rotation with a respective
one of two groups of cams, and a phaser mounted on the camshaft to
enable the phase of at least one of the rotary members to be varied
dynamically relative to the phase of the crankshaft and the other
rotary member, wherein a thrust plate is integrated as part of the
camshaft and phaser assembly, the thrust plate being securable in
place after the camshaft and phaser have been fitted to the
cylinder block or cylinder head of the engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention will now be described further, by way of
example, with reference to the accompanying drawings, in which:
[0008] FIG. 1 is an end view of a camshaft and phaser assembly of a
first embodiment of the invention,
[0009] FIG. 2 is a section in the plane II-II of FIG. 1,
[0010] FIG. 3 is an end view of a camshaft and phaser assembly of a
second embodiment of the invention,
[0011] FIG. 4 is a section in the plane IV-IV in FIG. 3,
[0012] FIG. 5 is a perspective view from the rear of the camshaft
and phaser sub-assembly of FIG. 4,
[0013] FIG. 6 is an end view of a camshaft and phaser assembly of a
third embodiment of the invention,
[0014] FIG. 7 is a section in the plane VII-VII in FIG. 6,
[0015] FIG. 8 is an end view of a camshaft and phaser assembly of a
fourth embodiment of the invention,
[0016] FIG. 9 is a section in the plane IX-IX in FIG. 8,
[0017] FIG. 10 is an end view of a camshaft and phaser assembly of
a fifth embodiment of the invention,
[0018] FIG. 11 is a section in the plane XI-XI in FIG. 10, and
[0019] FIG. 12 is a perspective view from the front of the camshaft
and phaser sub-assembly of FIG. 11.
DETAILED DESCRIPTION
[0020] In all the embodiments of the invention to be described
herein, the camshaft is an SCP camshaft 10 comprising an inner
shaft 12 rotatable relative to an outer tube 14. Cams 16 of a first
set are directly mounted on the outer tube 14 for rotation with the
outer tube 14 and cams 18 of a second set are free to rotate about
the outer tube 14 and are connected for rotation with the inner
shaft 12 by means of pins 20 that pass through circumferentially
elongated holes in the outer tube 14. The outer tube is supported
in the engine cylinder head or block (not shown) by means of
bearing journals 13. The journals 13 are larger than the cams 16
and 18 so that the entire camshaft can be slid axially from the
front end of the engine into bearing blocks in the engine.
[0021] The phaser 30 is a hydraulic vane type phaser having an
input sprocket 32 driven from the engine crankshaft and two output
members each connected to drive a respective one of the inner shaft
12 and the outer tube 14 of the SCP camshaft. The phaser need not
be a vane-type phaser but vane-type phasers are preferred because
of their small size. As the construction of both SCP camshafts 10
and phasers 30 are known, it is not deemed necessary for an
understanding of the present invention to describe them in further
detail in the present context.
[0022] FIGS. 1 and 2 show a first embodiment of the invention,
where a camshaft thrust plate 40 is pre-mounted between the SCP
camshaft 10 and the phaser 30 and the fixings of the thrust plate
40 are positioned such that they can be tightened after the
camshaft and phaser have been assembled to the engine.
[0023] In this embodiment, it is possible to set the axial
clearance of the inner drive shaft of the SCP camshaft in the
camshaft tube and the axial clearance within the camshaft phaser
with a single shim 42 at the rear of the camshaft, the shim 42
being retained in place by means of a circlip 44.
[0024] FIGS. 3 to 5 show a second embodiment of the invention,
where a rear adjustment shim 142 also acts as the camshaft thrust
plate. In this case, the SCP camshaft 10 and phaser 30 assembly is
fitted from the front of the engine and then the rear thrust plate
142 and circlip 144 are fitted and screwed to the rear of the
cylinder block/head. This obviates the need for a conventional
thrust plate at the front of the engine.
[0025] The embodiment of FIGS. 6 and 7 has an alternative design of
rear adjustment shim 242 that is retained on the inner shaft of the
camshaft 10 by means of a bolt 246 rather than a circlip and
cooperates with a thrust plate 244 to resist axial movement of the
camshaft.
[0026] The embodiment shown in FIGS. 8 and 9 uses a rear engine
cover 340 to resist axial movement of the camshaft. This embodiment
also employs a further alternative design of a combined clearance
adjustment shim and rear thrust plate 342 that is secured to the
rear of the camshaft by a bolt 346. The thrust plate 342 controls
the axial camshaft position by contacting the rear of the cylinder
block 350 and a thrust face provided in the rear cover 340 fitted
over the rear of the camshaft. A rear cover of this sort is
conventionally used in some engines to retain oil in the rear
camshaft bearing and to mount the rear crankshaft oil seal.
[0027] The embodiment of the invention shown in FIGS. 10 to 12 uses
a shim 442 at the rear end of the camshaft 10 to control the axial
clearance of the SCP camshaft and phaser assembly, but does not use
a thrust plate at the rear to control the axial position of the
camshaft in the engine. Instead the camshaft axial position in the
engine is controlled between the front of the cylinder block and
the inside of a cover 450 fitted to the front of the engine. A face
is provided on the rear of the phaser assembly 30 to resist thrust
by contacting the front of the cylinder block and a face is
provided on the front of the phaser or camshaft to resist axial
thrust by contacting the inside of the front cover 450.
[0028] It is envisaged that in this embodiment of the invention the
front cover may be fitted with an oil-feed spigot 460 against which
the camshaft/phaser thrust would also be resisted. The oil-feed
spigot 460 is threaded into the cover 450 with a coarse thread so
that its position can be altered by a small angle of rotation in
order to set the end float of the camshaft once the cover has been
fitted to the engine. The spigot is secured in position by a
locknut 462 fitted to the outside of the cover 450 and a seal 464
is provided between the spigot 460 and its counter bore in the
cover to make sure that there is no leakage between oil feeds. This
spigot design has the advantage of ensuring that the oil ways in
the spigot line up with the corresponding oil passages in the
phaser because the spigot is controlling the axial position of the
phaser.
[0029] In some cases the control oil feeds are fed to the phaser
via the front camshaft bearing, in which case the cover could be
provided with an adjustable thrust plate of a much simpler design
because it would not have any internal oil passages.
[0030] The various embodiments of the invention described above
offer the following advantages when compared to existing designs:
[0031] The timing of the phaser and camshaft is fixed before
assembly to the engine. [0032] The phaser does not need to be a
separate unit that can be handled in isolation from the camshaft,
which allows greater design integration of the two parts. [0033]
The end float of the phaser and the inner drive shaft within the
camshaft tube may be set with a single `shim` for the whole
assembly. [0034] The thrust plate need not compromise the design of
the phaser connection to the camshaft.
* * * * *