U.S. patent application number 10/542170 was filed with the patent office on 2006-06-22 for device for actuating the gas exchange valves in reciprocating engines.
Invention is credited to Kai-Uwe Keller, Helmut Schon.
Application Number | 20060130786 10/542170 |
Document ID | / |
Family ID | 32694915 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060130786 |
Kind Code |
A1 |
Schon; Helmut ; et
al. |
June 22, 2006 |
Device for actuating the gas exchange valves in reciprocating
engines
Abstract
A device is described for actuating the charge-cycling valves
(V) in reciprocating internal combustion engines, consisting of a
housing (G); a cam (N) mounted in the housing (G) in a revolute
joint (ng) so as to be able to rotate, the rotational movement of
which cam is derived from a crankshaft; an intermediate member (Z)
activated by this cam (N) by way of a first cam joint (zn); and a
power take-off member (A) that transfers the movement to the valve
(V), and is connected to act with the intermediate member (Z),
directly or via other transfer elements, and at least one other cam
joint (za) is provided within the active connection from the first
cam joint (zn) to the power take-off member (A), whereby this other
cam joint (za) is formed by a cam (Kz or Ka, respectively) on one
of the two gear mechanism members (Z, A) that form the cam joint
(za), in and of themselves, the shape of which cam has at least one
point of inflection (W) in the contact region in which a valve lift
is produced, whereby the point of inflection (W) is disposed in the
region of the cam (Kz or Ka, respectively) that describes the
greatest possible valve lift. In order to minimize the forces, i.e.
moments between the gear mechanism members, and thus to keep the
reactive forces in the system as low as possible, it is proposed
that the point of inflection (W) be disposed in such a manner that
the surface normal in the contact point, at which the greatest
valve lift is achieved, is approximately equal to the surface
normal in the contact point, at which the highest valve
acceleration occurs.
Inventors: |
Schon; Helmut; (Frastanz,
AT) ; Keller; Kai-Uwe; (Kreuzlingen, CH) |
Correspondence
Address: |
Max Fogiel
44 Maple Court
Highland Park
NJ
08904
US
|
Family ID: |
32694915 |
Appl. No.: |
10/542170 |
Filed: |
January 7, 2004 |
PCT Filed: |
January 7, 2004 |
PCT NO: |
PCT/EP04/00035 |
371 Date: |
July 2, 2005 |
Current U.S.
Class: |
123/90.16 |
Current CPC
Class: |
F01L 2305/00 20200501;
F01L 13/0063 20130101; F01L 2013/0068 20130101; F01L 13/0005
20130101 |
Class at
Publication: |
123/090.16 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2003 |
DE |
103 02 260.0 |
Claims
1. Device for actuating the charge-cycling valves (V) in
reciprocating internal combustion engines, consisting of a housing
(G); a cam (N) mounted in the housing (G) in a revolute joint (ng)
so as to be able to rotate, the rotational movement of which cam is
derived from a crankshaft; an intermediate member (Z) activated by
this cam (N) by way of a first cam joint (zn); and a power take-off
member (A) that transfers the movement to the valve (V), and is
connected to act with the intermediate member (Z), directly or via
other transfer elements, and at least one other cam joint (za) is
provided within the active connection from the first cam joint (zn)
to the power take-off member (A), characterized In that this other
cam joint (za) is formed by a cam (Kz or Ka, respectively) on one
of the two gear mechanism members (Z, A) that form the cam joint
(za), in and of themselves, the shape of which cam has at least one
point of inflection (W) in the contact region in which the valve
has a valve lift that is greater than zero.
2. Device of claim 1, characterized in that the movement
transferring to the valve (V) can be changed by means of modifying
the position and the orientation of at least one gear mechanism
member or its joint positions to the housing (G).
3. Device of claim 1, characterized in that the cam joint (za) at
one of the two gear mechanism members (Z, A) forming the same is
formed by a cam (Kz or Ka, respectively), the shape of which has a
point of inflection (W) precisely in the contact region in which
the valve has a valve lift that is greater than zero.
4. Device of one of claims 1, characterized in that the point of
inflection (W) is disposed essentially in the region of the
starting and ending valve lift.
5. Device of one of claims 1, characterized in that the point of
inflection (W) is disposed in the region of the cam (Kz or Ka,
respectively) that describes the greatest possible valve lift.
6. Device of one of claims 1, characterized in that the cam joint
(za) is formed on the other of the two gear mechanism members (Z,
A) forming the same, by a cam (Ka or Kz, respectively), the shape
of which is formed by an arc or a circle.
7. Device of one of claims 1, characterized in that the cam joint
(za) is disposed between the intermediate member (Z) and the power
take-off member (A).
8. Device of one of claims 1, characterized in that the cam joint
(za) is disposed between the intermediate member (Z) and the
housing (G).
9. Device of one of claims 1, characterized in that the cam joint
(za) is disposed on a transfer member located between the
intermediate member (Z) and the power take-off member (A).
10. Device for actuating the charge-cycling valves (V) in
reciprocating internal combustion engines, consisting of a housing
(G); a cam (N) mounted in the housing (G) in a revolute joint (ng)
so as to be able to rotate, the rotational movement of which cam is
derived from a crankshaft; an intermediate member (Z) activated by
this cam (N) by way of a first cam joint (zn); and a power take-off
member (A) that transfers the movement to the valve (V), and is
connected to act with the intermediate member (Z), directly or via
other transfer elements, and at least one further cam joint (za) is
provided within the active connection from the first cam joint (zn)
to the power take-off member (A), characterized in that this
further cam joint (za) at one of the two gear mechanism members (Z,
A), which form the cam joint (za), in and of themselves, is formed
by a cam (Kz or Ka), the shape of which, in the contact region, in
which the transition from the region, in which no valve lift is
produced, into the region, in which a valve lift is produced, is
formed by a segment and an evolvent section.
11. Device for actuating the charge-cycling valves (V) in
reciprocating internal combustion engines, consisting of a housing
(G); a cam (N) mounted in the housing (G) in a revolute joint (ng)
so as to be able to rotate, the rotational movement of which cam is
derived from a crankshaft; an intermediate member (Z) activated by
this cam (N) by way of a first cam joint (zn); and a power take-off
member (A) that transfers the movement to the valve (V), and is
connected to act with the intermediate member (Z), directly or via
other transfer elements, and at least one other cam joint (za) is
provided within the active connection from the first cam joint (zn)
to the power take-off member (A), whereby this other cam joint (za)
is formed by a cam (Kz or Ka, respectively) on one of the two gear
mechanism members (Z, A) that form the cam joint (za), in and of
themselves, the shape of which cam has at least one point of
inflection (W) in the contact region in which a valve lift is
produced, whereby the point of inflection (W) is disposed in the
region of the cam (Kz or Ka, respectively) that describes the
greatest possible valve lift, characterized in that the point of
inflection (W) is disposed in such a manner that the surface normal
in the contact point at which the greatest valve lift is achieved
is approximately equal to the surface normal in the contact point
at which the highest valve acceleration occurs.
12. Device of claim 1, characterized in that the movement
transferring to the valve (V) can be changed by means of modifying
the position and the orientation of at least one gear mechanism
member or its joint positions to the housing (G).
13. Device of claim 1 or 2, characterized in that the cam joint
(za) at one of the two gear mechanism members (Z, A) forming the
same is formed by a cam (Kz or Ka, respectively), the shape of
which has a point of inflection (W) precisely in the contact region
in which the valve has a valve lift that is greater than zero.
14. Device of one of claims 1 to 3, characterized in that the cam
joint (za) is formed on the other of the two gear mechanism members
(Z, A) forming the same, by a cam (Ka or Kz, respectively), the
shape of which is formed by an arc or a circle.
15. Device of one of claims 1 to 4, characterized in that the cam
joint (za) is disposed between the intermediate member (Z) and the
power take-off member (A).
16. Device of one of claims 1 to 4, characterized in that the cam
joint (za) is disposed between the intermediate member (Z) and the
housing (G).
17. Device of one of claims 1 to 4, characterized in that the cam
joint (za) is disposed on a transfer member located between the
intermediate member (Z) and the power take-off member (A).
Description
[0001] The invention relates to a device for actuating the
charge-cycling valves in reciprocating internal combustion engines,
consisting of a housing; a cam mounted in the housing in a revolute
joint so as to be able to rotate, the rotational movement of which
cam is derived from a crankshaft; an intermediate member activated
by this cam by way of a first cam joint; and a power take-off
member that transfers the movement to the valve, and is connected
to act with the intermediate member, directly or via other transfer
elements, and at least one other cam joint is provided within the
active connection from the first cam joint to the power take-off
member.
[0002] A fully variable mechanical valve drive for a piston
internal combustion engine is described in DE-A 101 00 173, with
drive means for generating a lifting movement that acts counter to
the force of a closing spring in the charge-cycling valve, and with
an intermediate element disposed between the drive means, such as a
cam, and the charge-cycling valve. The element acts on the
charge-cycling valve in the direction of its axis of movement, and
the lift path of the element can be changed in the direction of the
axis of movement, by way of an adjustable guide element.
[0003] A variable valve drive for controlling the load of a
spark-ignited internal combustion engine is described in DE-A 100
06 018. The valve drive is formed from a cam of a camshaft and at
least one inlet valve having a direct valve activation member, the
power take-off member, a transfer member, and an adjustment means
for influencing the lift function of the transfer member. The
transfer member is installed as a drive between the cam and the
power take-off member, and has a first contact surface impacted by
the cam, as well as a second contact surface acting on the power
take-off member.
[0004] In the state of the art, there is a plurality of
mechanically variable valve drives for controlling or controlling
the load of reciprocating internal combustion engines. The
references cited above should therefore be viewed merely as
examples. It is a common feature of the systems mentioned that a
lift movement is transferred to the charge-cycling valve by means
of the rotational movement of the cam of a camshaft. The resulting
lifting curve of these charge-cycling valves can be changed during
operation, by means of displacement of at least one of the gear
mechanism members located in the force flow. In this connection,
both the valve lift and the valve opening angle are changed. In
order to make it possible for the displacement to be implemented,
at least one gear mechanism member is inserted between the driving
cam and the power take-off member that activates the charge-cycling
valve. In this way, at least one additional degree of freedom in
the movement is produced, so that the displacement desired, in each
instance, becomes possible.
[0005] In this connection, there are valve drives, which consist of
4, 5, 6, or more gear mechanism members. The most cost-advantageous
and simplest are the variable valve drives with four members. The
complexity of the systems increases with an increasing number of
gear mechanism members. The use of the inventive teaching therefore
preferably takes place on systems having four or five members,
although the teaching can also be used for systems having six or
more members.
[0006] The transfer of force and moment between the members of the
valve gear mechanism takes place by way of cam joints, sliding
joints, and revolute joints. The moving gear mechanism members are
supported in the housing directly or indirectly. The adjustment of
the lift movement of the valve takes place, for example, by means
of the displacement of joints or connecting link tracks in the
housing, on which gear mechanism members that are part of the force
flow are supported.
[0007] Important criteria of such valve gear mechanisms consist of
the fact that with the change in the valve lift, the opening angle,
i.e. the duration of the valve rest, is also changed, and that the
contract between cam and intermediate member is constantly
maintained.
[0008] Furthermore, the accelerations of the valve during valve
opening should be as high as possible. The position and contours of
the curve joints that are in engagement, as well as the position of
the various revolute joints and sliding joints serve as influence
factors for this purpose.
[0009] In the case of such valve drives, the forces are very
dependent on the rpm. The spring forces of the valve gear
mechanisms are designed in such a manner that the forces resulting
from acceleration do not result in a loss of contact in the cam
joints of the valve gear mechanism at the highest rpm for which the
system is designed.
[0010] In the rest region of the valve, the forces introduced into
the valve gear mechanism by the valve are zero. The control region
of the valve can be divided into the region, in which the highest
valve acceleration takes place and into the region, in which the
greatest valve lift takes place. The region, in which the highest
valve acceleration takes place, follows the rest region directly.
In this region, the highest forces occur at high engine speeds of
rotation, in a cam joint in which a gear mechanism member that
moves back and forth participates.
[0011] Such systems are designed, for the transition from the rest
region to the control region, in such a manner that the reactive
forces that occur in this region are minimized.
[0012] The region in which the greatest valve lift occurs follows
during the further progression of the valve lift. At high engine
speeds of rotation, the forces decrease here. In the state of the
art, however, the angle conditions in the gear mechanism change as
a result of the valve stroke, in such a manner that even if the
amounts of the forces that are introduced no longer increase, the
reactive forces that result from them can still increase.
[0013] Furthermore, it is frequently a significant disadvantage, in
the state of the art, that the adjustment forces, i.e. adjustment
moments are very high, because of the cam shapes that are selected,
so that disproportionately high forces must be introduced into the
participating gear mechanism members.
[0014] As a consequence of the disadvantages of the state of the
art described above, it may become necessary that at least
individual gear mechanism members bust be undesirably heavy so that
they achieve a specified service life.
[0015] It is an object of the invention to develop the device
described in the preamble of claim 1 or claim 10 further, in such a
manner, that the forces or moments between the gear mechanism
members, and if possible the forces or moments within the setting
device, are minimized. This means that the reactive forces in the
system are kept as low as possible. At the same time, this results
in an advantageous reduction in the friction forces.
[0016] This objective is accomplished with a device with the
distinguishing features of claim 1 or claim 10.
[0017] The force direction can be determined freely, within certain
limits, by means of the configuration of the contours participating
in the cam joint. By inserting a point of inflection in one of the
participating contours pursuant to the invention, the cam joint is
configured in such a manner, that the angle of the force
transmission remains as constant as possible during the entire
movement sequence. As a result, the change in the amount of force
introduced is kept as small as possible.
[0018] Studies have shown that the insertion of a point of
inflection is necessary only at a contour point of the cam joint
that is in contact at valve lifts, which are greater than 0.5 mm.
The range of valve lifts of 2 mm to 7 mm is particularly preferred
In the preferred range, in the event that the greatest possible
valve lift progression is selected, the valve acceleration has
negative values, since the valve speed is being decelerated. The
highest resulting reactive forces are to be expected specifically
here.
[0019] In the following, the effect of the invention will be
described using the example of the configuration of the cam joint
between the intermediate member and power take-off member, with the
inventive contour at the intermediate member. In the example, the
power take-off member is formed by a drag lever or rocker
lever.
[0020] The force introduced into the power take-off member is
determined by the acceleration, friction, and spring forces from
the valve, which is in operative connection with the power take-off
member. These forces are specified by the special design of the
engine. The values depend on the rpm of the engine and other
influencing factors.
[0021] A force, corresponding to the normal at the instantaneous
contact point of the cam joint between power take-off member and
intermediate member, is introduced into the intermediate member by
the power take-off member. The magnitude of the force, introduced
into the intermediate member, is determined by the ratio of the
distances between the point of rotation of the power take-off
member in the housing and the lines of action of the forces, on the
one hand, to the intermediate member and, on the other, to the
valve. The line of action of the force, in each case, is the
straight line, which is determined by the direction and the
location of the force. The directions of the forces therefore
essentially determine the force introduced into the intermediate
member. The lowest force is introduced into the intermediate member
if the direction of the force, introduced into the intermediate
member, is perpendicular to the line connecting the point of
rotation of the power take-off member with the contact point of the
force,
[0022] With the inventive object, the change in direction of the
force is determined by describing direction of the surface normal
in the contact point in this cam joint. To avoid the
above-mentioned reactive forces, it is advantageous to implement
the surface normal in the contact point, at which the greatest
valve lift is achieved, to be approximately equal to the surface
normal in the contact point, at which the highest valve
acceleration occurs. Such a change in direction can be implemented,
pursuant to the invention, by means of a point of inflection in one
of the two cams of the cam joint in question.
[0023] To adhere to the specified valve lift curve, the contour at
the cam, for example, is adapted correspondingly.
[0024] The mechanism of effect described above also applies when
cup tappet is used as the power take-off member and it must be
applied analogously.
[0025] Furthermore, the inventive teaching can also be applied to
valve gear mechanisms, in which the cam joint, configured pursuant
to the invention, is disposed at a location different from that
described above. In this connection, it is immaterial whether the
cam of a cam joint of the gear members, which engage one another,
is configured in this manner, or a cam in the housing, on which one
of the gear mechanism members is supported in a cam joint.
[0026] Advantageous further developments of the object of the
invention are evident from the dependent claims.
[0027] By means of the inventive object, a solution is now made
available by means of which the forces or moments between the gear
mechanism members, and if possible the forces or moments within the
adjustment device, are minimized. This means that the reactive
forces in the system are kept as low as possible, which at the same
time advantageously results in a reduction in the friction
forces.
[0028] The inventive object can be implemented, in general, in all
cam joints in the valve gear mechanism, with the exception of the
cam joint, in which the driving, rotating cam participates. The
inventive implementation of the cam of the cam joint at one of the
participating gear mechanism members acts on both of the gear
mechanism members that form this cam joint. It is therefore
immaterial on which of the two participating cams of the cam joint
the inventive embodiment is disposed. In the preferred embodiment
of the valve gear mechanism, the contour described in the object of
the invention is used on one of the cams of the intermediate
member. Preferably, in this connection, the cam joints of the
intermediate member to the power take-off member or to the housing
can be selected.
[0029] In an advantageous further development of the invention, in
addition to the formation of a point of inflection in the region of
the valve lift, the transition region from the rest region to the
control region is specifically represented. In this connection,
this transition region plays a significant role both for the
opening and for the closing of the valve. While the opening process
is supposed to take place as quickly as possible, the end phase of
the closing speed must be limited in order to limit wear and the
development of noise. Since the same transition region between the
rest region and the control region is passed through, the two
opposing requirements must be resolved with a compromise. The
direct transition region between the rest region and the control
region is formed from segment sections and evolvent sections.
[0030] The inventive object is shown in FIGS. 1 and 2 by means of
an example and is described as follows. In the drawing,
[0031] FIGS. 1 and 2 show different positions of a valve gear
mechanism for variable actuation of the charge-cycling valves in
reciprocating internal combustion engines.
[0032] FIGS. 1 and 2 show a device for actuating a charge-cycling
valve V in a reciprocating internal combustion engine, the details
of which are not shown. The device contains a housing G, a cam N
mounted in the housing G in a revolute joint ng so as to be able to
rotate, the rotational movement of which cam is derived from a
crankshaft, not shown in further detail. An intermediate member Z
is activated by this cam N, by way of a first cam joint zn, which
member acts on a power take-off member A that transfers the
movement to the valve V. A further cam joint za is provided in an
active connection from the first cam joint zn to the power take-off
member Z, which joint is formed by the contours Kz on the
intermediate member and Ka on the power take-off member. The shape
of the contour Kz on the intermediate member usually has a point of
inflection W2 precisely at the transition between the region in
which no valve lift takes place (the region of the valve being held
closed) and the region in which valve lift takes place (the control
region that exists during opening of the valve). Furthermore, the
shape of the contour Kz on the intermediate member has a point of
inflection W in the contact region in which a valve lift that is
greater than zero is produced. The point of inflection W is located
essentially in the region of the cam joint that is to be assigned
to the region of the starting and the ending valve lift. As is
particularly evident from FIG. 2, the point of inflection W is
disposed in the region of the cam Kz that describes the greatest
possible valve lift. The cam Ka is formed by an arc, in this
example, but other geometric shapes are also possible. The cam
joint za is disposed between the intermediate member Z and the
power take-off member A, in this example.
[0033] FIG. 1 essentially describes the region of the valve being
closed, i.e. valve lift s1-zero, while FIG. 2 describes that
control region that exists while the valve V is open, i.e. valve
lift s2>zero.
[0034] In the examples, only a single intermediate member Z is
provided. As described in the state of the art, of course,
additional transfer members can also be provided, so that these are
also covered by the scope of protection.
* * * * *