U.S. patent application number 11/357865 was filed with the patent office on 2006-09-07 for discrete mode variable valve gear.
Invention is credited to Emmanouel Pattakos, John Pattakos, Manousos Pattakos.
Application Number | 20060196459 11/357865 |
Document ID | / |
Family ID | 36942917 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196459 |
Kind Code |
A1 |
Pattakos; Manousos ; et
al. |
September 7, 2006 |
Discrete mode variable valve gear
Abstract
A valve lifter is activated selectively by one of a plurality of
cams, either via displaceable rollers or via tappets having
rotatable grooves on top, to provide discrete or stepwise multimode
operation and deactivation. The hydraulic control is only an option
since the pure mechanical control is adequate. Easy to retrofit
into existing engines.
Inventors: |
Pattakos; Manousos; (Nikea
Piraeus, GR) ; Pattakos; John; (Nikea Piraeus,
GR) ; Pattakos; Emmanouel; (Nikea Piraeus,
GR) |
Correspondence
Address: |
Manousos Pattakos
Lampraki 356 - GR18452
Nikea Piraeus
GR
|
Family ID: |
36942917 |
Appl. No.: |
11/357865 |
Filed: |
February 21, 2006 |
Current U.S.
Class: |
123/90.16 ;
123/90.27; 123/90.39 |
Current CPC
Class: |
F01L 1/185 20130101;
F01L 2305/00 20200501; F01L 2013/0068 20130101; F01L 2307/00
20200501; F01L 13/0036 20130101; F01L 1/08 20130101; F01L 13/0063
20130101; F01L 1/143 20130101 |
Class at
Publication: |
123/090.16 ;
123/090.27; 123/090.39 |
International
Class: |
F01L 1/34 20060101
F01L001/34; F01L 1/02 20060101 F01L001/02; F01L 1/18 20060101
F01L001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2005 |
GR |
20050100103 |
Mar 11, 2005 |
GR |
20050100123 |
Claims
1. A valve-operating system for an internal combustion engine,
comprising: a valve lifter moved in unison with a valve mounted in
an engine body; a plurality of cams, each one for providing a
specific operational mode to the valve, with at least one cam, of
said plurality of cams, being not in direct engagement to said
valve lifter; a roller for engaging said at least one cam with said
valve lifter; a displaceable engaging member mounted slidably or
pivotally or in other way on said engine, holding said roller and
providing the necessary reaction to said roller; said displaceable
engaging member has an activation position where said roller
engages said at least one cam and said valve lifter transferring
camming action from said at least one cam to said valve lifter, and
a deactivation position where said valve lifter is disengaged from
said at least one cam; so that said valve lifter can be activated
from different cams, depending on the position of the relevant
engaging members.
2. As in claim 1 wherein said roller abuts along a surface of said
displaceable engaging member.
3. As in claim 1 wherein said roller is supported on a rocker
pivotally mounted on said displaceable engaging member.
4. As in claim 1 wherein said valve lifter is a bucket lifter.
5. As in claim 1 wherein the engaging member has more than one
activation positions for providing additional valve lift
profiles.
6. As in claim 1 wherein said valve lifter activates more than one
valves.
7. A tappet cam follower reciprocating along a tappet guide of an
engine, the tappet cam follower is angularly displaceable, the
tappet cam follower cooperates with a set of cams mounted on a
camshaft of said engine, said set of cams comprises at least one
cam, characterized in that: the close to the camshaft side of the
tappet cam follower is configured such that at a first angular
position of the tappet cam follower it provides space to a cam, of
the set of cams, to rotate without actuating the tappet cam
follower, while at a second angular position of the tappet cam
follower the same cam actuates the tappet cam follower.
8. A tappet cam follower reciprocating along a tappet guide of an
engine, the tappet cam follower being actuated by at least one cam,
of a plurality of cams mounted on a camshaft of said engine, the
tappet cam follower is angularly displaceable about the axis of
said tappet guide, characterized in that the tappet cam follower is
configured such that it selectively engages and disengages at least
one cam, of the plurality of cams, according its angular
displacement.
9. As in claim 7, characterized in that said close to the camshaft
side of the tappet cam follower comprises grooves or gaps to allow,
at an angular position of the tappet cam follower, one or more of
the cams of the set of cams to pass through and thereby be
disengaged from the tappet cam follower.
10. As in claim 7, characterized in that said set of cams comprises
at least two cams of substantially the same profile, said at least
two cams are simultaneously engaged and disengaged to provide
substantially uninterruptible abutment between the camshaft and the
tappet cam follower despite the gaps on the tappet cam follower
surface.
11. As in claim 7, characterized in that the tappet cam follower
can be locked at additional angular positions in order to engage
and disengage additional cams or group of cams of the set of cams
and thereby to provide further modes of operation.
12. As in claim 7, characterized in that the set of cams comprises
high lift cams and low lift cams or no lift cams.
13. As in claim 7, characterized in that the tappet cam follower
comprises hydraulic lash adjuster.
Description
[0001] A valve lifter is activated selectively by one of a
plurality of cams, either via displaceable rollers or via tappets
having rotatable grooves on top, to provide discrete or stepwise
multimode operation and deactivation.
[0002] The pure mechanical control is adequate.
[0003] The closest prior art is the PCT/GR04/000043 patent
application.
[0004] In the continuously variable valve lift systems a unique cam
lobe, in cooperation with a control member, controls the motion of
a valve depending on the position of the control member. Although
the number of the valve lift curves is infinite, it is not
necessarily the desirable.
[0005] In the discrete or stepwise multimode systems, on the other
hand, the complexity of the valve lifters, the hydraulic control,
the impact transition from mode to mode and the inertia loads of
the idle parts are disadvantages which are solved with this
invention.
[0006] As shown in FIGS. 1 to 5, a typical roller finger follower
with hydraulic lash adjuster is actuated by cam lobes of different
profiles, mounted on the same camshaft. The cam lobes are not in
direct contact to the roller of the valve lifter. A first free
roller is trapped inside a properly machined groove on a first
engaging member, while a second free roller is trapped inside a
second engaging member.
[0007] In FIG. 2 the two engaging members are in the deactivation
positions, i.e. as the camshaft rotates, the two free rollers are
idle, not loading the system with their inertia and friction. The
valve is deactivated.
[0008] In FIG. 3, the left engaging member with its free roller has
come in its activation position and the soft cam lobe profile
activates the valve.
[0009] In FIG. 4, both engaging members with their free rollers
have come in their actuation positions, but only the wild cam lobe
can activate the valve.
[0010] In FIG. 5, the finger follower is shown in section view and
the wild cam engaging member is at a secondary activation position,
compared to its activation position shown in FIG. 4, for providing
a different valve lift profile. Only the right engaging member is
in activation position. The left engaging member is in deactivation
position, idle. Here the mild cam lobe can provide duration and
timing not limited by the respective values of the wild cam lobe.
When both engaging members are in their activation position, as
shown in FIG. 4, the wild cam lobe must provide higher lift and
sooner opening and later closing of the valve. The engaging member
can be mounted on the engine pivotally or slidably or with any
other known way in order to move from its activation position(s) to
its deactivation position.
[0011] The use of a free roller seems the simplest, strongest and
lightest solution. Nevertheless, as shown in FIG. 6, the right
roller is held on the engaging member by a pivotally mounted rocker
arm. The control here is hydraulic, i.e. oil is pressed into the
back side of a small cylinder displacing the rocker arm and the
roller till the activation position. Here the lash adjustment can
be accomplished by the oil of the cylinder without the need of
conventional lash adjuster.
[0012] It must be noted that the transition from deactivation to
mild mode and then to wild mode is progressive and may even last
for a few cycles of the engine in comparison to the impact/instant
transition.
[0013] In FIG. 7 it is shown another realization, even simpler, but
without deactivation capability. Here the soft cam lobes act
directly on the roller of the roller finger follower while the wild
cam lobe is selectively engaged depending on the position of the
engaging member.
[0014] In FIG. 8 it is shown the case where the valve lifter is a
bucket lifter.
[0015] It is obvious that the system can use more that the two or
the three steps described. Additional modes can be added easily
because when a cam is deactivated, the relevant engaging member and
the roller stay aside idle without adding their inertia.
[0016] The valve lifter may activate more than one valves.
[0017] The valve lifter can be a rocker arm pivotally mounted on a
pivot shaft.
[0018] The control of the system is easy because there is no need
for complicated oil passages inside the valve lifters, no need for
locking pins, no need for extreme accuracy etc. Here the control is
applied only on stationary like components.
[0019] In another embodiment, a valve operating system includes a
tappet cam follower combined with high lift and low lift or no lift
cams.
[0020] The tappet comprises grooves at its surface facing the
cams.
[0021] At one mode of operation the grooves are at a direction that
provides space to the high lift cam(s) to rotate without displacing
the tappet, so the tappet is actuated by the low lift or the no
lift cam(s).
[0022] At a second mode of operation the grooves are at a direction
that cancels the disengagement of the high lift cam(s), so the
tappet is actuated by the high lift cam(s).
[0023] The proper geometry of the system, including the tappet, the
grooves and the cams, provides smooth/continuous control of the
valve at all modes. The application is similar to the overhead
camshaft engines and to the side camshaft engines with
pushrods.
[0024] The profiles of the associated cams can be different from
valve to valve, to provide additional modes of engine operation,
like valve deactivation, cylinder deactivation etc.
[0025] The grooves can be machined directly on the top surface of
the tappet or on its lash adjuster.
[0026] Hydraulic or mechanical lash adjusters can be incorporated
as in conventional tappets.
[0027] The control of the system can be mechanical, hydraulic etc.
The objective of the control is to rotate and keep at the right
direction the grooves. Compared to the prior art two mode tappet,
the present is simpler, because it is nothing more than a
conventional tappet with some slots on it, it is lighter,
permitting higher revs and lower friction, it does not need extreme
construction accuracy or special materials, it is easily controlled
even mechanically, it is space effective permitting direct
application on existing engines as retrofit, etc.
[0028] In FIG. 9 it is shown the camshaft having three cams, a
central low lift cam and two high lift cams mounted at the two
sides of the central cam. In FIG. 10 the camshaft has been removed,
in FIG. 11 the tappet guide, i.e. the slider of the tappet, has
been removed and the tappet has been sliced.
[0029] In FIG. 12 when the tappet is rotated for about 180 degrees,
as shown at right side, the high lift cam is disengaged from the
tappet and the valve is displaced under the camming action of the
low lift cam, which in the case shown in FIG. 12, is a no lift cam
providing deactivation. In the general case the tappet shown in
FIG. 12 provides two different valve lift profiles.
[0030] In FIGS. 13 and 14 the tappet is at low lift mode.
[0031] In FIGS. 15 and 16 the tappet is at high lift mode. Compared
to FIGS. 13 and 14 the only difference is that the tappet is
rotated for about 50 degrees to cancel the disengagement of the
high lift cams. Provided that the camshaft at FIG. 14 and FIG. 16
is at the same angular position, the difference of the valve lift
is obvious.
[0032] In case the low lift cam lobe is a no lift cam, at low lift
mode the valve is deactivated.
[0033] FIG. 17 shows the valve lift for three different camshaft
angles, with the tappet at low lift mode.
[0034] FIG. 18 shows the valve lift for the same three cam shaft
angle, with the tappet at high lift mode.
[0035] In FIG. 19 it is shown the camshaft and the tappet. The
parallel dash lines define the slide ways, i.e. the paths of
contact, of the wild cam lobes along the tappet. The hatched areas
is where the relevant high lift cam completely loses contact with
the tappet. The geometry of the tappet, cams and grooves was
selected to provide permanent contact of at least one of the two
high lift cams during high lift mode. It is obvious that more cams
could be used, for instance three high lift cams with two low lift
cams between them. It is also evident that the exact angle of the
tappet at high lift mode is not critical.
[0036] The transition from high lift mode to low lift mode can be
done no matter what the camshaft angle is, but the transition from
the low lift mode to the high lift mode takes place with the valve
closed, otherwise the high lift cams that move inside the grooves
do not allow the tappet to rotate.
[0037] In FIG. 20 it is shown a way to control hydraulically the
rotation angle of the tappet. The tappet has a slot parallel to its
axis. The tappet guide or slider has a proper groove. Inside the
groove is displaced a "piston" that holds the tappet angularly, at
its slot. The "piston" is displaced along the tappet guide groove
via pressurized oil, shifting angularly the tappet.
[0038] In FIG. 21 it is shown a way for mechanical control. Here
the tappet has slots at its lower end, while a guide member has
reverse slots permitting the free reciprocation of the tappet and
providing, when necessary, the required torque to rotate the tappet
to the other mode or to keep the tappet at its present mode. To
apply the mechanical control in a row of tappets, what is necessary
is a rod or shaft connected elastically to each one of the tappets
of the row. The elastic connection, via springs, etc, is necessary
due to the fact that the transition from the low lift mode to the
high lift mode can be done only when the valve is closed. Another
simple way to rotate the guide member is by pressurized oil,
pistons, cylinders etc.
[0039] In FIG. 22 it is shown the case of a three mode tappet. The
camshaft has a short lift central cam located between two high lift
cams, while two more medium lift cams are located outside the two
high lift cams. The parallel dash lines mark the slide ways, or
paths of contact, of the cams along the tappet. At bottom left it
is shown the tappet at short lift mode. In this the grooves on the
top of the tappet disengage the high lift and the medium lift cams.
At bottom centre it is shown the medium lift mode. In this case
another set of grooves disengage the high lift cams. At bottom
right it is shown the tappet at high lift mode. In a similar way
additional modes can be added. In case that the short lift cam is
replaced by a no lift cam, the short lift mode becomes a
deactivation mode.
[0040] It is obvious that cams of the same maximum valve lift, but
providing different valve lift profiles, can be used.
* * * * *