U.S. patent application number 13/697184 was filed with the patent office on 2013-03-07 for multi-cylinder internal combustion engine with variable actuation of the engine valves.
This patent application is currently assigned to FIAT POWERTRAIN TECHNOLOGIES S.P.A.. The applicant listed for this patent is Antonio Balzano, Clino D'epiro. Invention is credited to Antonio Balzano, Clino D'epiro.
Application Number | 20130055973 13/697184 |
Document ID | / |
Family ID | 43064512 |
Filed Date | 2013-03-07 |
United States Patent
Application |
20130055973 |
Kind Code |
A1 |
D'epiro; Clino ; et
al. |
March 7, 2013 |
MULTI-CYLINDER INTERNAL COMBUSTION ENGINE WITH VARIABLE ACTUATION
OF THE ENGINE VALVES
Abstract
In a multi-cylinder internal combustion engine, valves of the
engine, in particular the exhaust valves (3), are actuated by
rocker arms (18) each of which is rotatably mounted on the
structure of the engine with the interposition of an eccentric
bushing (39), whose rotation allows varying the position of the
rotational axis of the respective rocker arm, so as to activate and
deactivate an extra-lift of the engine valve. The eccentric
bushings (38) associated to the rocker arms (18) of the various
cylinders of the engine are all connected in rotation with a common
shaft (100) which is rotatably supported on the structure of the
engine and which can be rotated through actuator means (105)
preferably arranged outside the engine.
Inventors: |
D'epiro; Clino; (Turin,
IT) ; Balzano; Antonio; (Turin, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
D'epiro; Clino
Balzano; Antonio |
Turin
Turin |
|
IT
IT |
|
|
Assignee: |
FIAT POWERTRAIN TECHNOLOGIES
S.P.A.
Turin
IT
|
Family ID: |
43064512 |
Appl. No.: |
13/697184 |
Filed: |
April 15, 2011 |
PCT Filed: |
April 15, 2011 |
PCT NO: |
PCT/IB11/51645 |
371 Date: |
November 9, 2012 |
Current U.S.
Class: |
123/90.11 ;
123/90.15 |
Current CPC
Class: |
F01L 13/0026 20130101;
F01L 1/26 20130101; F01L 13/06 20130101; F01L 1/181 20130101; F01L
1/3442 20130101 |
Class at
Publication: |
123/90.11 ;
123/90.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34; F01L 9/04 20060101 F01L009/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2010 |
EP |
10425154.1 |
Claims
1. Multi-cylinder internal combustion engine, comprising, for each
cylinder, a combustion chamber with at least one intake conduit and
at least one exhaust conduit intake valves and exhaust valves
associated to said conduits and biassed by spring means towards a
closed condition of the respective conduit, at least one camshaft
for controlling the abovementioned valves, each valve being movable
towards an opened condition of the respective conduit, against the
action of the respective spring means, by a cam of the
abovementioned camshaft by means of a mechanical transmission
including a rocker arm rotatably mounted on the structure of the
engine, wherein each of the rocker arms associated to the exhaust
or intake valves of the engine is rotatably mounted on the
structure of the engine with the interposition of an eccentric
bushing, and wherein actuator means are provided for rotating the
abovementioned eccentric bushings associated to the rocker arms
controlling the valves of the various cylinders, to vary the
position of the rotation axis of the rocker arms, characterised in
that the abovementioned eccentric bushings associated to the rocker
arms of the various cylinders of the engine are all connected in
rotation with a common support shaft which is rotatably supported
on the structure of the engine, and in that said actuator means are
arranged to control a rotation of the abovementioned common support
shaft.
2. Engine according to claim 1, characterised in that said actuator
means are positioned outside the structure of the engine.
3. Engine according to claim 1, characterised in that said actuator
means are chosen among actuator means of the pneumatic type,
actuator means of the electric type and actuator means of the
hydraulic type.
4. Engine according to claim 1, characterised in that interposed
between the actuator means and the abovementioned common support
shaft is a mechanical transmission, such as a linkage or a
gearing.
5. Engine according to claim 1, characterised in that the
abovementioned common support shaft is rotatably supported within
seats partly defined by supports forming part of the cylinder head
of the engine and partly by caps fixed onto said supports.
6. Engine according to claim 1, characterised in that said actuator
means are hydraulically controlled actuator means, including a
rotor connected in rotation with said common support shaft and
rotatable within a stator fixed onto the structure of the engine,
said stator and rotor defining hydraulic chambers therebetween
which can be selectively connected by means of a control valve to a
hydraulic supply and a reservoir.
7. Vehicle, in particular an industrial vehicle, characterised in
that it has an engine according to claim 1.
Description
FIELD OF THE INVENTION AND PRIOR ART
[0001] The present invention refers to multi-cylinder internal
combustion engines of the type indicated in the preamble of the
attached claim 1. Engines of this type are illustrated in documents
EP 0 543 210 B1, EP 1 927 734 A2 and EP 1 927 735 A1.
[0002] Compression braking systems for internal combustion engines,
in particular for reciprocating engines such as diesel engines for
heavy duty vehicles, are known. In these engines compression
braking allows attaining extremely high specific braking powers,
especially simultaneously with a supercharging performed by means
of turbochargers with variable geometry.
[0003] It is known that such systems provide for a supplementary
opening of the cylinder exhaust valve during braking, to avoid the
expansion of the air in the cylinder after the compression stage,
thus reducing the braking efficiency.
[0004] In order to attain such results there have been proposed
various types of devices, among which in particular devices for
varying the position of the rotational axis of the rocker arms
which control the opening of exhaust valves.
[0005] FIG. 1 of the attached drawings shows the solution known
from EP 0 543 210 B1. In such figure, number 1 is used
to--generally designate a multi-cylinder internal combustion
engine, in particular a turbocharged diesel engine, comprising--for
each cylinder--a combustion chamber (not shown in the drawing) with
at least one intake conduit (also not shown in the drawing) and at
least one exhaust conduit (the illustrated example shows two
exhaust conduits 9 converging into an exhaust manifold 10).
According to the conventional art, associated to the exhaust
conduits 9 are exhaust valves 3 biassed by respective springs 13
towards an upper (with reference to the drawing) closed position of
the respective conduits. The engine further comprises, still
according to the conventional art, at least one camshaft with cams
36 for controlling the valves, which for example can be a single
camshaft intended to control both the intake valves and the exhaust
valves. Each exhaust valve 3 of each engine cylinder is
displaceable towards a lowered (with reference to FIG. 1) position
for opening the respective exhaust conduit, against the action of
the respective spring 13, by a rocker arm 18 rotatably mounted
around a rotation axis O on the structure of the engine. The rocker
arm 18 has one end freely rotatably supporting a roller 27 which
cooperates with a respective cam 36 of the camshaft. The other end
of the rocker arm controls the displacement of the two exhaust
valves 3 associated to each cylinder, by means of a bridge-like
structure (naturally a single exhaust valve for each cylinder may
obviously be provided which is controlled directly by the end of
the respective rocker arm).
[0006] Still according to the abovementioned prior art solution,
the cam 36 has a main lobe 58 to obtain the lifting of the exhaust
valves during the exhaust stage of the operating cycle of the
respective cylinder, a zero lift portion 56, which does not
determine any lift of the exhaust valves, and a portion 57 slightly
lifted with respect to the circular base profile for attaining a
slight extra lift of the exhaust valves during the compression
stage in the respective cylinder, which extra lift is
actuated--simultaneously with an interruption of fuel supply to the
combustion chamber--when an engine braking effect is requested.
[0007] Still according to the known solution illustrated in FIG. 1,
the rocker arm 18 is rotatably mounted on a fixed axle onto the
structure of the engine with the interposition of an eccentric
bushing 39 whose angular position around the support axis may be
varied. In the specific case of the illustrated example, this is
done through a fluid actuator 46, also illustrated in FIG. 1, which
operates on a lever 45 connected in rotation with the bushing 39.
The variation of the angular position of the bushing 39 determines
a variation of the position of the rotation axis of the rocker arm
18 with respect to the structure of the engine. When the
engine-braking effect is not required, the position of the rotation
axis of the rocker arm is selected in such a manner that the arm 18
is unaffected, due to the existing clearance, by the portion 57 of
the profile of the cam 36, thus the extra-lift of the exhaust
valves is not activated during the cylinder compression stage. On
the contrary, when one wants to obtain the engine braking effect,
the supply of fuel to the cylinders is cut off and the eccentric
bushings 39 of the various rocker members are rotated in such a
manner that the latter "feel" the profile 57 and cause the
abovementioned extra-lift. In such manner, the braking effect
caused by the engine during the compression stage of each cylinder
is not jeopardised by an elastic re-expansion of the air in the
cylinder during the subsequent stroke of the piston towards the
Bottom Dead Centre, in that at least part of the air has been
evacuated from the cylinder in the meanwhile.
DRAWBACKS OF THE PRIOR ART
[0008] Though guaranteeing the advantages indicated above, the
aforedescribed prior art device is not entirely satisfactory in
terms of simplicity and cost of manufacture. Further devices of
this type have been proposed in EP 1 927 734 A2 and EP 1 927 735 A1
in the attempt to simplify and reduce the number of required
components but they are yet to attain an actually satisfactory
result.
OBJECT OF THE INVENTION
[0009] The object of the present invention is that of proposing a
device of the aforedescribed type capable of allowing a dramatic
simplification of the device itself with respect to those proposed
previously and an ensuing dramatic reduction of the production
costs.
SUMMARY OF THE INVENTION
[0010] The main characteristic of the invention is indicated in the
characterizing part of the attached claim 1.
[0011] As visible, the invention provides for, equivalently to the
prior art solution described above, that the rocker arms associated
to the valves (in particular to the exhaust valves) of the various
cylinders of the engine be rotatably supported by interposing
eccentric bushings, which may be rotated to vary the position of
the rotational axis of the rocker arms.
[0012] However, the eccentric bushings are not rotatably mounted
each on a respective fixed axle, but rather they are connected in
rotation on a common shaft which is rotatably supported by the
structure of the engine.
[0013] Due to this kind of solution, the adjustment of the angular
position of all the eccentric bushings associated to the various
cylinders of the engine may be obtained simultaneously, through
actuator means of any type suitable to rotate the abovementioned
common shaft to which the eccentric bushings are connected in
rotation.
[0014] For example, among various types of actuator means, a
hydraulically controlled actuator device may be provided of a type
similar to conventional devices used for adjusting the camshaft
phase, comprising a rotor connected in rotation with the shaft
supporting the eccentric bushings, and a stator fixed onto the
structure of the engine and surrounding the rotor, with hydraulic
means for the variation of the angular position of the rotor with
respect to the stator. In any case, it is surely possible to use
actuators of any other type, such as hydraulic, electric or
pneumatic actuators, or also a transmission between the actuator
means and the driven shaft, to increase the transmitted torque, for
example a crank connected to the shaft supporting the eccentric
bushings and actuated by a fluid linear actuator, or a gear
transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Further characteristics and advantages of the invention will
become apparent from the description that follows with reference to
the attached drawings, provided strictly for exemplifying and
non-limiting purposes, wherein:
[0016] FIG. 1 illustrates the device for controlling the exhaust
valves of a cylinder of an internal combustion engine according to
the art known from EP 0 543 210 B1,
[0017] FIG. 2 is a schematic perspective view illustrating the base
principle of the present invention,
[0018] FIG. 3 is a further schematic perspective view of the device
according to the invention, and
[0019] FIG. 4 is a diagram of a possible example of an actuator
used in the device according to the invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0020] The prior art solution illustrated in FIG. 1 has already
been described above. The main difference of the present invention
with respect to such known solution is immediately evincible from
FIG. 2 of the attached drawings. Such difference essentially lies
in the fact that the eccentric bushings 39 associated to the rocker
arms 18 for the actuation of the exhaust valves of the various
cylinders of the engine are connected in rotation to a common shaft
100, instead of being freely rotatably mounted on respective axles.
In the case of the embodiment illustrated in FIG. 2, the bushings
39 are connected in rotation on the shaft 100 by means of
transverse pins 101 engaging diametric holes formed through the
shaft 100 and corresponding holes diametrically opposite with
respect to each other formed on each bushing 39. It is however
clear that any other type of connection may be used.
[0021] Likewise, the embodiment visible in the drawings shows that
the shaft 100 is rotatably supported by the structure of the engine
within respective seats 102 which are defined partly by supports
103 forming part of the structure of the cylinder head of the
engine and partly by caps 104 (only one of which is visible in the
drawings) fixed by means of screws 104a (FIG. 3) to the supports
103. Preferably low friction support bearings are provided in the
seats in which the shaft 100 is mounted.
[0022] Due to the abovementioned characteristic, the device
according to the invention enables simultaneous adjustment of the
angular position of all the eccentric bushings 39, in order to
obtain the activation and deactivation of the extra-lift of the
exhaust valves which has been discussed above with reference to
figure 1, by simply controlling a rotation of the common shaft 100
to which the eccentric bushings 39 are fixed.
[0023] As previously indicated, the actuator means used for
controlling the rotation of the shaft 100 may be of any type. In
the case of the example illustrated in the attached drawings, a
hydraulically controlled actuator is procided of a type similar to
that used conventionally used for adjusting the camshaft phase.
According to this art, known per se, the actuator, generally
designated by reference number 105, comprises a rotor 106 with
blades 106a which is connected in rotation with the shaft 100 and
rotates within a circular stator 107 with internal blades 107a. As
better visible in FIG. 4, defined between the rotor 106 and stator
107 are hydraulic chambers which are selectively connected to a
supply pump 108 and a reservoir 109 through a control valve 110, in
such a manner to control the adjustment of the angular position of
the shaft 100 and hence of the eccentric bushings 39.
[0024] As clearly apparent from the foregoing description, the
device according to the invention allows using one actuator for
simultaneously controlling the adjusting of the position of the
rocker members 18 controlling the exhaust valves of the engine
cylinders. Not only is the device extremely simple and inexpensive
to manufacture but it also allows a considerable reduction of the
number of components with respect to the solutions proposed
previously. The device according to the invention also allows
easily positioning the actuator device even outside the engine,
with the ensuing advantages even in terms of reducing the
temperature and vibrations to which the actuator is subjected and
thus also avoiding any restrictions regarding the dimensions of the
actuator and/or the type of actuator one intends to use.
[0025] As indicated severally, the means for actuating the rotation
of the shaft 100 for supporting the eccentric bushings 39 may be of
any type, and in particular they may be of pneumatic type,
hydraulic type or electric type.
[0026] Furthermore, the device according to the invention would be
identically applicable even to distribution systems using a
different kinematic chain for controlling the valves, with levers
of a different type with respect to the rocker arms indicated
herein. Therefore, in the claims that follow, the term "rocker arm"
shall be considered to include the case of any lever having a
rotational movement around one axis.
[0027] Additionally, as previously indicated, a further preferred
example of actuator means could be made up of a linear hydraulic
actuator connected to a crank lever connected to the shaft 100. A
mechanical transmission (for example a linkage or a gearing) may be
generally interposed to increase the torque transmitted to the
shaft 100.
[0028] It should also be observed that the eccentric bushings 39
may be each formed in a single piece or also in several pieces
connected to each other. Furthermore, should the rocker arms that
control the intake valves be mounted on the same rotational axis of
the rocker arms which control the exhaust valves, the intake rocker
arms may be freely rotatatably mounted on the abovementioned common
support shaft 100, in such a manner to be unaffected by the
rotations of the latter.
[0029] Furthermore, the invention is obviously also theoretically
applicable to devices for actuating the intake valves of the
engine, in any desired case in which, for any reason, it is
required to activate or de-activate an extra-lift of the intake
valves through simple and inexpensive means. Lastly, the device is
also applicable in any other case in which one desires to obtain an
extra-lift of the exhaust valves, to obtain effects different from
that of compression braking.
[0030] Naturally, without prejudice to the principle of the
invention, the details and embodiments may vary, even
significantly, with respect to what has been described and
illustrated strictly for exemplification purposes, without
departing from the scope of the present invention.
* * * * *