U.S. patent application number 09/681523 was filed with the patent office on 2001-11-22 for cam angle sensor mounting structure for engine.
Invention is credited to Uchida, Masahiro.
Application Number | 20010042527 09/681523 |
Document ID | / |
Family ID | 18653035 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042527 |
Kind Code |
A1 |
Uchida, Masahiro |
November 22, 2001 |
Cam angle sensor mounting structure for engine
Abstract
An improved journaling and sensor mounting arrangement for the
VVT mechanisms of a twin overhead cam engine. By utilizing a
combined single bearing cap for the VVT ends of the camshafts that
mounts the sensors that are associated with timing wheels on the
respective camshafts, it is possible to maintain a very neat
external appearance and a compact construction. Also, high accuracy
can be obtained because of the positive rotation of the components.
In addition, a simplified oil supply and control arrangement is
also disclosed for lubricating the thrust surfaces of the camshaft
bearings and other bearing surfaces as well as supplying hydraulic
fluid to the VVT mechanisms.
Inventors: |
Uchida, Masahiro;
(Iwata-shi, JP) |
Correspondence
Address: |
ERNEST A. BEUTLER
ATTORNEY AT LAW
500 NEWPORT CENTER DRIVE
SUITE 945
NEWPORT BEACH
CA
92660
US
|
Family ID: |
18653035 |
Appl. No.: |
09/681523 |
Filed: |
April 23, 2001 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 2001/34433
20130101; F01L 2001/34436 20130101; F01L 2820/041 20130101; F01L
2001/34496 20130101; F01L 2001/0537 20130101; F01L 1/46 20130101;
F01L 1/34 20130101; F01L 1/0532 20130101; F01L 1/02 20130101; F01L
1/022 20130101; F01L 2001/3444 20130101; F01L 1/3442 20130101; F01L
2001/0476 20130101; F01L 1/26 20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2000 |
JP |
2000-146735 |
Claims
1. An internal combustion engine comprised of an engine body
providing a number of axially spaced bearing sections, a plurality
of axially spaced bearing caps fixed to said engine body and
cooperating with said bearing sections for journalling axially
spaced bearing surfaces of a camshaft, a variable valve timing
mechanism associated with one end of said camshaft for driving said
camshaft in an adjustable, timed fashion from an engine crankshaft,
one of said journalled camshaft bearing surfaces being juxtaposed
to said variable valve timing mechanism, a timing member formed on
said camshaft on the side of said one of said journalled camshaft
bearing surfaces opposite to said variable valve timing mechanism,
and a timing sensor cooperating with said timing member for
providing a signal indicative of camshaft angle, said timing sensor
being carried by the bearing cap journalling said one of said
journalled camshaft bearing surfaces.
2. An internal combustion engine as set forth in claim 1 wherein
the one journalled camshaft bearing surface is located at one end
of the camshaft.
3. An internal combustion engine as set forth in claim 1 wherein
the engine body is provided with a cover that encloses at least in
part the camshaft and the bearing cap journalling said one of said
journalled camshaft bearing surfaces and the timing sensor has a
portion extending through said cover.
4. An internal combustion engine as set forth in claim 1 wherein
the journalled cam shaft bearing surface is bounded by a pair of
thrust flanges engaged with the bearing cap journalling the one of
said journalled camshaft bearing surfaces for axially locating the
camshaft.
5. An internal combustion engine as set forth in claim 4 wherein
the variable valve timing mechanism is hydraulically operated.
6. An internal combustion engine as set forth in claim 5 wherein
the thrust flanges are lubricated from the same source as operates
the variable valve timing mechanism.
7. An internal combustion engine as set forth in claim 6 wherein
the lubricant for the thrust flanges is supplied through the
bearing cap journalling the one of said journalled camshaft bearing
surfaces.
8. An internal combustion engine as set forth in claim 1 wherein
there is further provided a second camshaft journalled about an
axis parallel to the axis of the first mentioned camshaft by a
second number of axially spaced bearing sections of the engine body
, a second plurality of axially spaced bearing caps fixed to said
engine body and cooperating with said bearing sections for
journalling axially spaced bearing surfaces of said second
camshaft, a second variable valve timing mechanism associated with
one end of said second camshaft for driving said second camshaft in
an adjustable, timed fashion from the engine crankshaft, one of
said journalled second camshaft bearing surfaces being juxtaposed
to said second variable valve timing mechanism, a second timing
member formed on said second camshaft on the side of said one of
said journalled second camshaft bearing surfaces opposite to said
second variable valve timing mechanism, and a second timing sensor
cooperating with said second timing member for providing a signal
indicative of the camshaft angle of said second camshaft, said
second timing sensor being carried by the bearing cap of the second
plurality journalling said one of said second journalled camshaft
bearing surfaces.
9. An internal combustion engine as set forth in claim 8 wherein
the bearing caps carrying the timing sensors comprise a single
bearing cap providing bearing surfaces for each of the
camshafts.
10. An internal combustion engine as set forth in claim 8 wherein
the one journalled camshaft bearing surface of each of the
camshafts are located at the same end of both of the camshafts.
11. An internal combustion engine as set forth in claim 8 wherein
the engine body is provided with a cover that encloses at least in
part the camshafts and the bearing caps journalling said one of
said journalled camshaft bearing surfaces and the timing sensors
each have a portion extending through said cover.
12. An internal combustion engine as set forth in claim 9 wherein
the journalled cam shaft bearing surface of each camshaft is
bounded by a pair of thrust flanges engaged with the common bearing
cap for axially locating the camshafts.
13. An internal combustion engine as set forth in claim 12 wherein
the variable valve timing mechanisms are hydraulically
operated.
14. An internal combustion engine as set forth in claim 13 wherein
the thrust flanges are lubricated from the same source as operates
the variable valve timing mechanisms.
15. An internal combustion engine as set forth in claim 14 wherein
the lubricant for the thrust flanges is supplied through the common
bearing cap.
16. An internal combustion engine as set forth in claim 9 wherein
the timing sensors are mounted on the common bearing cap at the
ends of respective elongated mounting plates and lie over the axis
of rotation of the associated camshaft.
17. An internal combustion engine as set forth in claim 16 wherein
the ends of the elongated plates spaced from the carried timing
sensor are connected to the common bearing cap between the axes of
rotation of the camshafts.
Description
BACKGROUND OF INVENTION
[0001] This invention relates to four-cycle internal combustion
engines and more particularly to an improved variable valve timing
control and journalling arrangement for the camshafts of such an
engine.
[0002] It has been recognized that the performance of an engine can
be improved through a wide variety of engine speeds and loads by
employing a variable valve timing (VVT) mechanism. In this way, the
valve timing can be optimized for the particular running condition
so as to provide the desired performance. Generally, the variable
valve timing mechanism is interposed in the drive of the camshaft
from the engine crankshaft and frequently is mounted on one end of
the associated camshaft. When twin overhead camshafts are employed,
it is common to have the variable valve timing mechanisms at the
same end of the respective camshafts.
[0003] In order to perfect the control, it is also necessary or
desirable to have a sensor associated with each of the camshafts so
as to sense the angular position of the respective camshaft.
Various arrangements have been proposed for mounting the camshaft
sensor and those methods, which have been proposed, have some
disadvantages.
[0004] In accordance with one method, the camshafts have a timing
wheel or the like mounted at one end thereof, normally the end
opposite from the variable valve timing mechanism. A sensor is
fixed to the engine body adjacent this timing wheel so as to
provide the signal indicative of the camshaft position.
[0005] One way in which the sensor may be mounted is by supported
it from the bearing cap for this end of the camshaft. This means
that the camshaft is elongated beyond the bearing surface so as to
accommodate the mounting of the timing wheel and associated sensor.
This presents problems inasmuch as the engine is elongated by such
an arrangement.
[0006] Another form of sensor for camshaft angle mounts the sensor
on the cam cover of the engine. However, this is a rather imprecise
way of monitoring the position due to the fact that the cam cover
is not always accurately positioned relative to the camshaft or the
cylinder head. That is, a sealing gasket is interposed between the
cam cover and the cylinder head and this can permit the cam cover
and accordingly the sensor to shift relative to the camshaft.
[0007] Although keying of the cam cover to the cylinder head can be
employed to avoid this problem, this complicates the assembly and
nevertheless, there still can be variations in the spacing between
the cam cover and the cylinder head even though the axial alignment
may be maintained. Also, this keying can generate some engine noise
since the silencing of the effect of the gasket is eliminated.
[0008] Another way of mounting the sensor is by fastening it
directly to the cylinder head itself. However, such mounting may
place the sensor in a juxtaposed position to the either the intake
or the exhaust sides of the cylinder head. This can cause
difficulties, particularly undo heating of the sensor if positioned
adjacent the exhaust side as generally must be done when the
angular position of the exhaust camshaft is being sensed. Also,
this can present difficulties in mounting the electrical leads for
conveying signals from the sensor to the control for the VVT
mechanism.
[0009] It is, therefore, a principal object to this invention to
provide an improved camshaft sensor arrangement for a four-cycle
internal combustion engine wherein the sensor is accurately mounted
and does not cause elongation of the engine nor routing problems
for the electrical conduits.
[0010] It is a further object to this invention to provide an
improved and simplified sensor mounting arrangement particularly
for multiple camshaft engines wherein each camshaft has a variable
valve timing mechanism associated with it.
SUMMARY OF INVENTION
[0011] This invention is adapted to be embodied in a four-cycle
internal combustion engine having an engine body with a plurality
of axially spaced bearing sections. A plurality of axially spaced
bearing caps are fixed to the engine body and cooperate with the
bearing sections for journaling axially spaced bearing surfaces of
a camshaft. A variable valve timing mechanism is associated with
one end of the camshaft for driving the camshaft in an adjustable,
timed fashion from an engine crankshaft. One of the journalled
camshaft bearing surfaces is juxtaposed to the variable valve
timing mechanism. A timing member is formed on the camshaft on the
side of the one journalled camshaft bearing surface opposite to the
variable valve timing mechanism. A timing sensor cooperates with
the timing member for providing a signal indicative of camshaft
angle. The timing sensor is carried by the bearing cap that
journals the one of the journal camshaft bearing surfaces.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a top plan view showing one end of a cylinder head
of an internal combustion engine constructed in accordance with an
embodiment of the invention, with the cam cover removed, and with
portions of the valve actuating mechanism eliminated in order to
more clearly show the construction.
[0013] FIG. 2 is a front elevational view of the structure shown in
FIG. 1 and illustrates the cam cover in place and shows the control
valve mechanism associated with the variable valve timing
mechanism.
[0014] FIG. 3 is a cross sectional view taken through the cylinder
head and generally along the axis of one of the camshafts.
[0015] FIG. 4 is a perspective view showing the bearing cap for the
driven ends of the camshafts with the timing sensors mounted
therein.
[0016] FIG. 5 is a perspective view looking from below showing one
of the timing sensors.
[0017] FIG. 6 is a cross sectional view taken generally through the
timing sensor and associated timing wheel formed integrally with
one of the camshafts.
[0018] FIG. 7 is a schematic hydraulic diagram showing the
lubricating oil passages and control mechanism for the intake and
exhaust valve timing mechanisms.
DETAILED DESCRIPTION
[0019] Referring now in detail to the drawings and initially
primarily to FIGS. 1 through 3, a portion of an internal combustion
engine constructed and operated in accordance with the invention is
identified generally by the reference numeral 11. Since the
invention deals primarily with the camshaft driving and bearing
arrangement for the engine 11, only the cylinder head structure of
the engine 11 is depicted. This comprises a main cylinder head
member 12 to which a cam cover 13 is detachably affixed in a well
known manner. A timing case, indicated generally by the reference
numeral 14, is formed at the front of the cylinder head member 12
and is closed by a timing case cover 15 at the lower end and by the
cam cover 13 at the upper end. This cover 15 also encloses the
un-shown front portion of the cylinder block to which the cylinder
head member 12 is affixed in the manner to be described.
[0020] The main cylinder head member 12 forms a plurality of
combustion chambers and, in the illustrated embodiment, each
combustion chamber is served by two intake valves and two exhaust
valves. These valves are not illustrated in the drawings but the
valves are operated by thimble tappets that are received within
bores 16 formed in the cylinder head member 12. Since this type of
construction is well known in the art, it is not believed necessary
to illustrate the valves and their association with the cylinder
bores.
[0021] However, the cylinder head member 12 is affixed to an
associated cylinder block (not shown) by threaded fasteners, one of
which is shown in FIG. 3, and which is identified by the reference
numeral 17. These threaded fasteners 17 are passed through four
fasteners holes 18 formed at the peripheral edges of the associated
cylinder head member 12 around each cylinder bore and threaded into
tapped openings in the associated cylinder block to affix the
cylinder head member 12 to the cylinder block in a manner that is
well known in the art.
[0022] Journalled in the cylinder head member 12, in a manner to be
described, is an intake camshaft 19 and an exhaust camshaft 21.
These camshafts 19 and 21 rotate about respective rotational axes
CI and CE. The intake camshaft 19 has individual cam lobes 22 that
are associated with the un-shown tappets in the tappet bores 16 on
the intake side of the engine. In a like manner, the exhaust
camshaft 21 has exhaust lobes 23 that cooperate with the tappets in
the tappet bores 16 on the exhaust side of the engine. Again, this
type of structure is well known in the art and, for that reason,
further details of its construction are not believed to be
necessary to understand the construction and operation of the
invention.
[0023] At axially spaced positions along its length, the intake and
exhaust camshafts 19 and 21 are formed with axially spaced bearing
surfaces 24 and 25, respectively, that are journalled in bridges 26
formed in the cylinder head member 12 at spaced locations along its
length. Individual bearing caps (not shown) are affixed to each of
the bridges 26 by threaded fasteners that are received in tapped
holes 27 formed between the respective lobes 22 and 23 associated
with each cylinder.
[0024] A central spark plug well 28 is formed in the cylinder head
member 12 at the center of each cylinder bore and receives a spark
plug for firing the charge in the combustion chambers in a manner
well known in the art.
[0025] In addition to the spaced bearing surfaces 24 and 25 of the
intake and exhaust camshafts 19 and 21, respectively, each camshaft
has an end bearing surface 29 and 31, respectively. These end
bearing surfaces 29 and 31 are journalled in an upstanding front
end wall 32 of the cylinder head member 12 which is adjacent the
timing case 14.
[0026] Each camshaft 19 and 21 is formed with a pair of thrust
faces 33 and 34, respectively, that are engaged with machined
surfaces formed on the cylinder head wall 32 for providing axial
location for the intake and exhaust camshafts 19 and 21.
[0027] A unitary bearing cap assembly, indicated generally by the
reference numeral 35, is affixed to the cylinder head wall 32 by
threaded fasteners 36 that are received in tapped holes formed
therein and which pass through openings 37 (FIG. 4) formed in the
respective bearing cap portions that cooperate with the respective
cylinder head bearing surfaces formed by the wall 32. These bearing
portions are joined by a partially cantilevered bridging part 38 of
the bearing cap member 35. This bridging part 38 has a further
opening 39 to receive a further threaded fastener that engages the
cylinder head member 12 to provide rigidity for the cantilevered
bridging part 38.
[0028] Continuing to refer primarily to FIGS. 1 through 3, the
drive for driving the intake and exhaust camshafts 19 and 21, which
is contained within the timing case 14 will now be described. A
first timing chain 41 is entrained around a suitable sprocket
affixed to the crankshaft of the engine and a tensioner pulley.
This chain 41 drives a first sprocket part 42 of a two sprocket
assembly that is connected to the intake camshaft 19 via a first
VVT mechanism 43. This VVT mechanism will be described in more
detail later.
[0029] Integrally formed with the first sprocket 42 is a second
sprocket 44 which, in turn, drives a further timing chain 45 that
drives a sprocket 46 that is connected to the exhaust camshaft 21
by a second VVT mechanism, indicated generally by the reference
numeral 47. It will be seen that the WT mechanisms 43 and 47 are
staggered relative to each other so as to provide clearance for the
timing chain 41 and crankshaft driven timing sprocket 42. This
permits a very compact assembly and also accommodates the drive of
the camshafts 19 and 21 at one half-crankshaft speed while
maintaining a close relationship between the camshaft rotational
axes CI and CE.
[0030] A chain tensioner 53 is carried by the cylinder head member
12 and tensions the timing chain 45 that transfers the drive from
the intake camshaft 19 to the VVT mechanism 47 for the exhaust
camshaft 21.
[0031] The VVT mechanisms 43 and 47 may be of any known type and,
in the illustrated embodiment, are of the sliding vane type that
includes respective pairs of fluid chambers 48 and 49 (VVT 43) and
51 and 52 (VVT 47). These chambers 48 and 49 and 51 and 52 are
pressurized selectively, in a manner, which will be described
shortly, so as to vary the phase angle between the camshafts 19 and
21 and also between these camshafts and the crankshaft.
[0032] The hydraulic control arrangement for supplying fluid to
actuate the VVTs 43 and 47 as well as lubricating the camshaft
bearings, will now be described by particular reference to FIGS. 2,
3 and 7 although certain of the components also appear in other
figures. As seen in FIG. 2, a main oil gallery 54 is formed in the
cylinder head member 12 and cooperates with a corresponding main
oil gallery formed in the associated cylinder block. An enlarged
bore is formed at the upper end of the oil gallery 54 and receives
a replaceable filter element 55 for filtering the oil delivered to
solenoid actuated, spool, intake and exhaust timing control valves
56 and 57, respectively.
[0033] The main gallery 54 is intersected by a transversely
extending gallery 58 that extends across the cylinder head member
12 and which is intersected the spools of the control valves 56 and
57. The solenoid actuated spool valve 56 selectively supplies
pressure to the chambers 48 and 49 of the intake VVT mechanism 43
through passages 59 and 61, which are formed in the cylinder head
member 12. In a like manner, the chambers 51 and 52 of the exhaust
VVT mechanism 47 are selectively supplied with lubricating oil from
the solenoid operated control valve 57 through passages 62 and 63,
respectively.
[0034] This system also provides an arrangement for lubricating the
bearings of the intake and exhaust camshafts 19 and 21. The main
gallery 58 of the cylinder head member 12 downstream of the filter
55 is intersected by a pair of further supply passages, 64 which
communicate with drillings 65 and 66 (FIG. 7) formed in the intake
and exhaust camshafts 19 and 21. These drillings intersect
longitudinally extending drillings 67 and 68 that are formed in the
intake and exhaust camshafts 19 and 21, respectively. The drillings
67 and 68 are intersected by radial drillings 70 formed at each of
the bearing surfaces including the bearing surfaces 25 and 31 of
the exhaust camshafts as shown in FIG. 3 and like drillings formed
in the intake camshaft.
[0035] These drillings 67 and 68 also terminate in axially
extending drillings 69 and 71, respectively, formed in the bearing
cap 35 which terminate at the respective thrust faces 33 and 34 for
lubricating these highly loaded surfaces. Thus, the system provides
very effective hydraulic supply and lubrication control.
[0036] The sensor arrangement for sensing the rotational position
of the intake and exhaust camshafts 19 and 21 will now be described
by primary reference to FIGS. 1 through 6. It will be seen the
cantilevered bridging portion 38 of the front bearing cap 35 is
provided with a pair of openings that receive and pass a sensor 75
of a sensor mounting assembly 76. This sensor mounting assembly 76
has a somewhat egg-shaped supporting bracket 77 from which the
sensor 75 depends and passes into proximity with respective timing
wheels 78 and 79 associated with the intake and exhaust camshafts
19 and 21, respectively. These timing wheels 78 and 79 have, in the
illustrated embodiment, four individual teeth or lugs 81. As these
lugs they pass the respective sensor element 75 it will generate a
signal. This may be done either magnetically or through a
photosensitive device. The mounting bracket portions 77 are formed
with further openings 82 that receive threaded fasteners that are
tapped into the cantilevered portion 38 of the bearing cap 35 so as
to hold them against rotation. Because these devices extend
inwardly, the elongation of the assembly is avoided and a very
compact assembly results.
[0037] As seen in FIG. 3, the cam cover 1 3 is provided with an
opening through which a portion of the mounting part 77 and sensor
75 can pass so as to provide an electrical connector 83 which
transfers the signals to the control ECU for the variable valve
timing mechanisms 43 and 47. An elastic seal 84 is mounted in a
groove in the cam cover 13 around its opening so as to sealingly
engage the mounting part 77 of the assembly and thus, provide good
sealing while maintaining a simple external electrical
connection.
[0038] Therefore, from the foregoing description it should be
readily apparent to those skilled in the art that the device
provides a very compact yet highly effective sensor and lubricating
arrangement as well as varying arrangements for the twin overhead
camshafts. Of course, the foregoing description is that of a
preferred embodiment of the invention and various changes and
modifications may be made without departing from the spirit and
scope of the invention, as defined by the appended claims.
* * * * *