U.S. patent application number 14/128813 was filed with the patent office on 2014-06-19 for device for actuating a valve of an internal combustion engine.
This patent application is currently assigned to VALEO SYSTEMES DE CONTROLE MOTEUR. The applicant listed for this patent is Nicolas Gelez, Julien Hobraiche, Gabriel Kopp. Invention is credited to Nicolas Gelez, Julien Hobraiche, Gabriel Kopp.
Application Number | 20140165936 14/128813 |
Document ID | / |
Family ID | 46579199 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140165936 |
Kind Code |
A1 |
Gelez; Nicolas ; et
al. |
June 19, 2014 |
DEVICE FOR ACTUATING A VALVE OF AN INTERNAL COMBUSTION ENGINE
Abstract
The invention relates to a cam actuator (2) for actuating at
least one valve (3) slidably mounted in a mounting (1), the device
comprising a tappet (8) which is to be mounted on a free end of a
stem (3a) of the valve and which is mobile relative to the mounting
(1); and a resilient return means (9) for the tappet, which to urge
the tappet (8) against the cam (2), characterised in that the
device comprises an electromagnetic locking means including an
electromagnetic actuator (22) having a coil (24), preferably
outside the tappet (8), and at least one pin (12) subjected to the
magnetic field of the actuator (22), such that supplying power to
the coil (24) causes the selective movement of the pin (12) between
a locked position, in which the tappet (8) is translatably linked
to the valve (3), and an unlocked position, in which the tappet (8)
freely slides on the stem (3a) of the valve.
Inventors: |
Gelez; Nicolas; (Le Pecq,
FR) ; Hobraiche; Julien; (Chevrieres, FR) ;
Kopp; Gabriel; (Clichy, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gelez; Nicolas
Hobraiche; Julien
Kopp; Gabriel |
Le Pecq
Chevrieres
Clichy |
|
FR
FR
FR |
|
|
Assignee: |
VALEO SYSTEMES DE CONTROLE
MOTEUR
Cergy Saint Christophe
FR
|
Family ID: |
46579199 |
Appl. No.: |
14/128813 |
Filed: |
June 27, 2012 |
PCT Filed: |
June 27, 2012 |
PCT NO: |
PCT/FR2012/051479 |
371 Date: |
January 30, 2014 |
Current U.S.
Class: |
123/90.11 |
Current CPC
Class: |
F01L 1/143 20130101;
F01L 13/0005 20130101; F01L 1/06 20130101; F01L 1/205 20130101;
F01L 2820/031 20130101 |
Class at
Publication: |
123/90.11 |
International
Class: |
F01L 1/06 20060101
F01L001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2011 |
FR |
1155718 |
Claims
1. A device for actuating by a cam at least one valve slidably
mounted in a support, the device comprising: a tappet mounted at a
free end of a stem of the valve and mobile relative to the support:
return spring means for the tappet adapted to cause the tappet to
bear against the cam; and electromagnetic locking means including
an electromagnetic actuator, the actuator comprising a coil
external to the tappet, and at least one pin subjected to the
magnetic field of the actuator so that energization of the coil
drives selective movement of the pin between a locked position in
which the tappet is coupled to the valve so as to move in
translation therewith, and an unlocked position in which the tappet
slides freely on the valve stem.
2. The device as claimed in claim 1, wherein the tappet includes an
opening designed to receive slidably the valve and the pin is
configured to slide perpendicularly to the valve between an
activation position in which the pin projects into the opening to
constrain the tappet to move in translation with the valve, and a
deactivation position in which the pin is retracted from the
opening to allow the tappet to slide freely on the valve stem (3a,
103a), the electromagnetic actuator being configured to move the
pin selectively between the activation position and the
deactivation position.
3. The device as claimed in claim 1, wherein the pin is totally
integrated into the tappet.
4. The device as claimed in claim 2, wherein, in the activation
position, the pin is received in a housing in a sleeve coupled to
the valve.
5. The device as claimed in claim 2, wherein, in the activation
position, the pin bears on one end of the valve stem in order to
lock the tappet to the valve.
6. The device as claimed in claim 5, wherein the pin includes a
flat designed to bear on the end of the valve stem.
7. The device as claimed in claim 1, wherein said magnetic coil of
the electromagnetic actuator is designed to extend perpendicularly
to the valve so that the axial component of the magnetic field
generated moves the pin.
8. The device as claimed in claim 1, wherein said magnetic coil of
the electromagnetic actuator is designed to extend parallel to the
valve so that the radial component of the magnetic field generated
moves the pin.
9. The device as claimed in claim 7, further comprising a plurality
of pins.
10. The device as claimed in claim 9, wherein the locking means
include two diametrally opposite pins sliding in opposite
directions to lock or unlock the tappet.
11. The device as claimed in claim 9, wherein each pin has a
respective electromagnetic actuator.
Description
[0001] The present invention concerns the field of controlling
internal combustion engines, in particular four-stroke engines,
and, to be more precise, disconnection of the inlet valves of an
internal combustion engine, for example a gasoline engine.
BACKGROUND OF THE INVENTION
[0002] An engine comprises an engine block delimiting chambers
known as combustion cylinders having one end closed by a cylinder
head and an opposite end closed by a piston received slidably in
the chamber. Each combustion chamber is associated with air and
fuel inlet means and with burned gas exhaust means. The efficiency
of internal combustion engines depends notably on the amount of air
filling the combustion chambers.
[0003] To improve the efficiency of internal combustion engines it
is preferable to keep the engine operating within regions in which
the filling rate is maximum. In the case of a low load on the
engine, a control system of the internal combustion engine allows
to pass only the quantity of air necessary to meet the engine load.
The consequence of this is to cause hunting of the engine and to
degrade the efficiency of the engine. To extend the optimum
operating range, notably when the engine is operating at half-load,
it is known to deactivate half of the combustion chambers so as to
increase the unit load of the combustion chambers remaining
active.
[0004] The combustion chambers are deactivated by neutralizing the
inlet and exhaust valves of said chambers.
[0005] It is known to use for this purpose a device for actuating
at least one valve by means of a cam, as described in the document
U.S. Pat. No. 5,878,705. Such a device includes a valve sliding in
the cylinder head and maintained in a stable closed position by a
valve spring. The valve is used to block an inlet hole feeding air
to the combustion chamber to which the inlet hole leads or an
exhaust hole through which the burned gases resulting from
combustion escape from the combustion chamber. The valve stem is in
contact with a hydraulic thrust valve inserted in a sleeve. A
tappet is slidably mounted on the sleeve. A camshaft actuates the
valve by acting either on the sleeve or on the tappet. Selection is
effected by means of a pin that can be moved by an actuator fed
with a hydraulic fluid between a connected position in which the
sleeve is coupled to the tappet and a disconnected position in
which the tappet slides freely on the sleeve. The pin actuator is
fed by a hydraulic circuit the pressure in which is produced by a
hydraulic pump actuated by the engine.
[0006] It is difficult to use this device, however, because it
necessitates the use of hydraulic circuits and a camshaft with
multiple cams. Apart from the complexity of developing such a
device, the response times of hydraulic actuators are too long for
it to be possible to establish efficacious engine management
strategies. The response time of a hydraulic actuator depends on
the feed pressure in the hydraulic circuit or on temperature and
therefore directly on the engine operating conditions.
OBJECT OF THE INVENTION
[0007] The object of the invention is to provide a device for
actuating at least one valve by means of a cam and enabling at
least some of the above drawbacks to be remedied.
BRIEF DESCRIPTION OF THE INVENTION
[0008] To achieve the above object, the invention proposes a device
for actuating by means of a cam at least one valve slidably mounted
in a support, the device including a tappet designed to be mounted
at a free end of a stem of the valve and mobile relative to the
support, and return spring means for the tappet adapted to cause
the tappet to bear against the cam, characterized in that the
device includes electromagnetic locking means adapted to be
selectively actuated between a locked position in which the tappet
is coupled to the valve to move in translation therewith and an
unlocked position in which the tappet slides freely on the valve
stem.
[0009] The actuating device is notably actuated by the cam
directly, i.e. by contact of the cam with the actuating device with
no intermediary element. The use of electromagnetic locking means
enables the response times to be reduced and the hydraulic circuit
to be dispensed with. This facilitates integration of the actuating
device into a support such as a cylinder head.
[0010] The tappet advantageously includes an opening designed to
receive slidably the valve, the locking means including at least
one pin adapted to slide perpendicularly to the valve between an
active position in which the pin projects into the opening to
constrain the tappet to move in translation with the valve and a
deactivation position in which the pin is retracted from the
opening to allow the tappet to slide freely on the valve stem, the
locking means including an electromagnetic actuator for selectively
moving the pin between the activation position and the deactivation
position.
[0011] The pin is therefore actuated remotely, i.e. without
mechanical contact between the pin that constitutes the active part
of the tappet and the electromagnetic actuator.
[0012] For example, the electromagnetic actuator generates a field
only when the locking means are no longer actuated. This is notably
the case on the back of the cam.
[0013] The electromagnetic actuator is preferably external to the
tappet. The electromagnetic actuator therefore does not move in
translation with the tappet. There is therefore no mobile
connection for energizing an electromagnetic actuator mounted in
the tappet. A mobile connection is typically fragile and there is
the risk of it breaking over a large number of cycles. The
electromagnetic actuator is notably stationary and is designed in
particular to be positioned in the support.
[0014] The pin is preferably totally integrated into the tappet.
The pin therefore does not come into contact with the support. The
actuating device is therefore subject to little friction on
actuation of the valve.
[0015] The electromagnetic actuator advantageously includes a
magnetic coil perpendicular to the valve so that the axial
component of the magnetic field generated moves the pin.
[0016] In particular, said magnetic coil has a coil axis
substantially parallel to the direction of movement of the pin.
[0017] The coil is notably integrated into the support and is
stationary relative thereto.
[0018] In the activation position, the pin advantageously bears on
one end of the valve stem in order to lock the tappet to the
valve.
[0019] The locking means advantageously include two diametrally
opposite pins sliding in opposite directions to lock or unlock the
tappet.
[0020] The electromagnetic actuator advantageously includes a
magnetic coil parallel to the valve so that the radial component of
the magnetic field generated moves the pin.
[0021] In particular, said magnetic coil has a coil axis
substantially perpendicular to the direction of movement of the
pin.
[0022] Each pin advantageously includes a flat designed to bear on
the end of the valve stem.
[0023] The device advantageously includes a plurality of pins.
[0024] Each pin advantageously has a respective electromagnetic
actuator.
[0025] The invention also concerns a device for actuating by means
of a cam at least one valve slidably mounted in a support, the
device including a tappet designed to be mounted at a free end of a
stem of the valve and mobile relative to the support, and return
spring means for the tappet adapted to cause the tappet to bear
against the cam, characterized in that the device includes
electromagnetic locking means including an electromagnetic actuator
including a coil, preferably external to the tappet, and at least
one pin subjected to the magnetic field of the actuator so that
energization of the coil drives selective movement of the pin
between a locked position in which the tappet is coupled to the
valve so as to move in translation therewith and an unlocked
position in which the tappet slides freely on the valve stem.
[0026] This device may have one or more of the features described
above.
[0027] In particular, in one embodiment the tappet includes an
opening designed to receive the sliding valve and the pin is
configured to slide perpendicularly to the valve between an
activation position in which the pin projects into the opening to
block movement of the tappet in translation on the valve and a
deactivation position in which the pin is retracted from the
opening to allow the tappet to slide freely on the valve stem, the
electromagnetic actuator being configured to move the pin
selectively between the activation position and the deactivation
position.
[0028] Other features and advantages of the invention will emerge
from a reading of the following description of particular
nonlimiting embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Reference will be made to the appended drawings provided by
way of nonlimiting example and in which:
[0030] FIG. 1 is a diagrammatic partial view of a valve actuating
device in accordance with a first embodiment of the invention in a
connected mode;
[0031] FIGS. 2 and 3 are diagrammatic views of the complete device
shown in FIG. 1 respectively in the connected mode and in a
disconnected mode;
[0032] FIG. 4 is a partial diagrammatic view of a valve actuating
device in accordance with a second embodiment of the invention in
the disconnected mode;
[0033] FIGS. 5 and 6 are diagrammatic views of the complete device
shown in FIG. 4 respectively in the connected mode and in the
disconnected mode.
DETAILED DESCRIPTION OF THE INVENTION
[0034] FIG. 1 shows a detail of a device in accordance with a first
embodiment of the invention used on an internal combustion engine
the structure of which is known in itself and will not be described
in more detail here. The device is mounted on a cylinder head 1
forming a support. The device is adapted selectively to transmit
the movement of a cam 2 fastened to a rotating shaft to a valve 3
mounted in a well in the cylinder head 1 to slide along an axis X
(there can be seen in FIG. 1 only an end 4 of a stem 3a of the
valve 3). The valve 3 notably enables opening and closing of a
combustion chamber or cylinder (not represented). The movement of
the cam 2 is transmitted directly. The complete device is more
specifically shown in FIGS. 2 and 3, which will be described
later.
[0035] The end 4 of the stem 3a of the valve includes a spring cup
5 fixed to the stem 3a of the valve by two fixing half-cones 6 in a
manner that is known in itself. The spring cup 5 receives on a
first face 5a a valve spring 7 bearing on the cylinder head 1 so as
to hold the valve 3 closed. Such a valve arrangement being moreover
known to the person skilled in the art, it will not be described in
more detail here.
[0036] The device includes a tappet 8 mounted in the well in the
cylinder head 1 to slide along the same axis X as the valve 3 and
to be in contact with the cam 2. A tappet spring 9 is disposed in
the tappet 8, bearing against a second face 5b of the spring cup 5
and the tappet 8 in order to maintain the contact between said
tappet 8 and the cam 2. Rotation of the tappet 8 is indexed
relative to the cylinder head 1 by a key 10 received in a
complementary groove 11 machined in the well of the cylinder head
1. The tappet 8 is therefore angularly indexed relative to the
cylinder head 1 so that it moves only in translation relative to
the cylinder head 1.
[0037] The tappet 8 is pierced at its center by a housing extending
along the axis X and containing a sleeve 14 adapted to slide freely
in said housing of the tappet 8. The sleeve 14 includes a key 15
that is received in a complementary groove 16 machined in the
tappet 8. The sleeve 14 is therefore angularly indexed relative to
the tappet 8 and can move only in translation along the axis X of
the valve 3.
[0038] The sleeve 14 has at its center a bore into which is
inserted a clearance-compensating shim 20 that comes into contact
with the end 4 of the stem 3a of the valve 3. The sleeve 14, the
shim 20 and the stem 3a form a stack in the direction of the axis X
of rigid elements adapted to transmit a force from the sleeve 14 to
the valve 3.
[0039] As shown in FIG. 1, the sleeve 14 and the tappet 8 are
adapted to define a plane bearing surface for the cam 2. However,
the cam 2, which here is a double-lobe cam, is adapted to bear only
on the tappet 8. The double-lobe shape of the cam 2 enables the
area of contact of the cam 2 on the tappet 8 to be distributed on
either side of the axis in order to balance the forces and
therefore to limit wear of the parts.
[0040] The device also includes electromagnetic locking means
including a ferromagnetic pin 12. The ferromagnetic pin slides
freely in a bore in the tappet 8 along an axis Y perpendicular to
the axis X of movement of the tappet 8.
[0041] The sleeve 14 includes a cylindrical housing 17 on the axis
Y adapted to receive the end of the pin 12.
[0042] The electromagnetic locking means also include an
electromagnetic actuator 22 for moving the pin 12 between two
extreme positions. The actuator 22 includes a body 23 including a
coil 24 and a ferromagnetic core 25 for directing the magnetic
field emitted by the coil 24.
[0043] The body 23 of the actuator 22 is disposed in the cylinder
head 1 in line with the pin 12 so that the magnetic field emitted
by the coil 24 of the actuator 22 is directed substantially along
the axis of movement of the pin 12, i.e. the axis Y. Energization
of the coil 24 therefore drives the movement of the pin 12
subjected to the magnetic field of the actuator 22. In other words,
the pin 12 is moved by virtue of the effect of the axial component
of the magnetic force of the electromagnetic actuator 22 produced
in particular by the coil 24.
[0044] In particular, the magnetic coil 24 has a coil axis
substantially parallel to the direction of movement of the pin
12.
[0045] The actuator 22 further includes a pin spring 26 adapted to
urge the pin 12 away from the body 23 of the actuator 22. To be
more precise, the pin spring 26 holds the pin 12 in a position
projecting into the housing 17 of the sleeve.
[0046] The tappet 8, the sleeve 14 and the cylinder head 1 are
indexed angularly relative to each other in order to enable
alignment in the same plane of the body 23 of the actuator 22, the
pin 12 and the opening 17.
[0047] The actuator 22 enables movement of the pin 12 between an
activation position in which the pin 12 projects into the housing
17 of the sleeve 14 in order to couple together the sleeve 14 and
the tappet 8 and a deactivation position in which the pin 12 is
retracted from the housing 17 to release the sleeve 14 and the
tappet 8.
[0048] FIG. 2 shows the device with the pin 12 in the activation
position to couple together the tappet 8 and the sleeve 14. The
movement of the cam 2 is therefore transmitted successively to the
tappet 8, then to the sleeve 14, then to the shim 20 and finally to
the valve 3. In the activation position, the cam 2 drives the
movement of the valve 3 which then allows exchange of cool gases
(inlet) or burned gases (exhaust) between the interior and the
exterior of the combustion chamber.
[0049] FIG. 3 shows the device in the disconnected position with
the pin 12 in the deactivated position. In this position, the
tappet 8 slides freely relative to the cylinder head 1 and relative
to the stack comprising the sleeve 14, the shim 20 and the valve 3.
The tappet spring 9 being sized to be more flexible than the valve
spring 7, the movements of the cam 2 are transmitted only to the
tappet 8, the valve 3 then remaining closed. When the pin 12 is in
the deactivation position the cam 2 is therefore disconnected from
the valve 3, which remains closed.
[0050] This embodiment is shown with only one pin 12 and only one
electromagnetic actuator 22. Of course, the device may include a
plurality of actuators and pins distributed around the valve at the
circumference of the device.
[0051] The clearance-compensating shim 20 may advantageously
include a hydraulic thrust bearing to compensate for wear of the
parts. Such a thrust bearing being moreover known in itself, it
will not be described in more detail here.
[0052] Other embodiments of the invention are equally possible.
FIG. 4 shows in detail a device in accordance with a second
embodiment of the invention. This second embodiment includes
numerous parts shared with the first embodiment. In this second
embodiment, parts identical or similar to those of the first
embodiment will therefore be numbered with the same reference
increased by 100. Thus the tappet 8 will be numbered 108 in this
second embodiment.
[0053] In this second embodiment, the device is mounted on a
cylinder head 101, as before, forming a support, selectively to
transmit the movement of a cam 102 to a valve 103 held closed by a
valve spring 107. In other words, the valve spring 107 exerts a
return force on the valve 103 so that the valve 103 closes the
inlet port or the exhaust port.
[0054] The device includes a substantially bell-shaped tappet 108
and has cylindrical walls sliding in a bore in the cylinder head
and a cover 108a on which the cam 102 bears.
[0055] The tappet 108 further includes a sleeve 114, also
substantially bell-shaped, which is inserted into the tappet 108
and rigidly connected to the tappet 108. The sleeve 114 has a first
wall 114a that is separated from the cover 108a of the tappet 108
by a clearance-compensating shim 120. The sleeve 114 has a second
wall 114b separated from the cover 108a of the tappet 108 in order
to leave a gap between them, the second wall 114b being pierced at
its center by a housing in which the stem of the valve 3 slides
freely.
[0056] The stem 103a of the valve can therefore slide freely in the
sleeve between the first wall 114a and the second wall 114b of the
sleeve 114 and over a height H.
[0057] The device further includes electromagnetic locking means
122 including two diametrally opposite ferromagnetic pins 112a and
112b that are received in bores in the sleeve 114. The bores lead
into the housing of the sleeve 114 and extend in a direction
perpendicular to the sliding axis X of the valve 103.
[0058] Each pin 112 can slide in its bore between an activation
position in which the pin 112 projects into the housing to block
sliding of the valve stem 103a in the sleeve 114 and a deactivation
position in which the pin 112 is retracted from the housing to
allow the stem of the valve 3 to slide freely in the sleeve
114.
[0059] The locking means 112 include a pin spring 126 for each pin
112, the pin springs 126 being such that the pins 112 are held in
the activation position.
[0060] When the pins 112 are in the activation position, the valve
103 is therefore locked to the tappet 108 so that the movement of
the cam 102 is transmitted to the valve 3. The valve 103 is then
connected to the cam 102 (see FIG. 5).
[0061] When the pins 112 are in the deactivation position, the stem
of the valve 3 is unlocked and is able to slide in the sleeve 114
over a height H (see FIGS. 4 and 6). The valve 103 is then
disconnected from the cam 102. To be more precise, the movement of
the cam 102 is transmitted only to the tappet 108, which then
slides relative to the cylinder head 101 and to the valve 103.
[0062] The travel or height H of the stem of the valve 3 in the
sleeve 114 is at least equal to the travel imparted to the valve
103 by the cam 102 so that, in the disconnected mode, the movement
of the cam 102 never opens the valve 103.
[0063] The locking means 122 include at least one electromagnetic
actuator 122 for moving the pins 112. As shown in FIGS. 4 to 6, the
electromagnetic actuator 122 includes a body 123 containing an
annular magnetic coil 124. The coil 124 is integrated into the
cylinder head 101 and is wound in the form of a torus around the
tappet 108 to generate an electromagnetic field the axis of which
is substantially the axis X of movement of the valve 103. Such a
magnetic field enables the pins 112a and 112b extending radially
relative to the coil to be moved without it being necessary to
index the pins 112 angularly relative to the cylinder head 101. In
this second embodiment, the tappet 108 is free to rotate. Because
the coil 124 is wound around the tappet 108, electromagnetic
actuation is possible whatever the angular position of the tappet
108. The pins 112 are then moved by virtue of the effect of the
radial component of the radial force of the electromagnetic
actuator 122 produced in particular by the coil 124.
[0064] In particular, the magnetic coil 124 has a coil axis
substantially perpendicular to the direction of movement of the
pins 112.
[0065] The sleeve 114 may advantageously include a ferromagnetic
portion for channeling the magnetic field of the coil 124 along the
sliding axis of the pins 112.
[0066] More advantageously, each pin 112 may have at its end a flat
130 adapted to come into contact with the end of the valve stem
103a. The contact between the pin 112 and the valve stem 103a is
therefore plane-on-plane, which limits the contact pressure between
the two parts, also referred to as the Hertz pressure.
[0067] The contact between the two parts can be improved by
angularly indexing the pins 112 relative to the sleeve 114 to
enable the flats 130 to take up a position facing the end of the
valve stem 103a. The angular indexing of the pins 112 is effected
with a key, for example.
[0068] The second embodiment is shown with two diametrally opposite
pins. It is nevertheless possible to use only one pin or to the
contrary to use more than two pins.
[0069] As in the first embodiment, the clearance-compensating shim
120 may include a hydraulic thrust bearing for compensating the
distribution clearance. The distribution clearance is set between
0.05 and 0.2 mm, for example, thereby ensuring that the valve
remains on its seat in all cases, for example all operating
temperatures.
[0070] The changes from the connected mode to the disconnected mode
and from the disconnected mode to the connected mode are preferably
effected when the pin 12, 112 is aligned with the opening 17, 117,
i.e. when the tappet 14, 114 is at the top dead center position,
i.e. on the base circle of the cam 102. The pin 12, 112 then has a
very short time to engage in and disengage from the opening 17,
117. For example, in an application in which the valve 3, 103
contributes to an engine speed of 4000 rpm and for a lift spread
over a crankshaft angle of 240.degree., the pin 12, 112 has
approximately 20 ms to make the transition between a connected
state and a disconnected state.
[0071] Of course, the invention is not limited to the embodiments
described but encompasses any variant within the scope of the
invention as defined by the claims.
[0072] In particular, the actuators 22, 122 may be of the bistable
type with a magnetic pin 12, 112 so that it is then possible to
dispense with the pin spring 26, 126, the pin 12, 112 then moving
between a stable activation first position and a stable
deactivation second position.
[0073] Other electromagnetic actuators may equally be used. Thus it
is possible to use rotary actuators (of the stepper motor type)
that drive a crank connected to the actuator and enable movement of
the pin 12. The rotation axis of these rotary actuators is
preferably parallel to the axis X of the valve.
[0074] Thanks to its features, the device in accordance with the
invention is compact and relatively non-intrusive and can be
integrated into numerous existing cylinder heads 1, 101 subject to
simple reboring of the bore for the tappet 8, 108. No oil nut needs
to be provided. The device also provides for disconnection systems
that are independent from one valve 3, 103 to another.
* * * * *