U.S. patent application number 10/547056 was filed with the patent office on 2006-07-27 for assembly and torsional stop device for roller tappets of a drive in an internal combustion engine.
Invention is credited to Matthew Evans, Christof Faria, Peter Sailer, Oliver Schnell.
Application Number | 20060162679 10/547056 |
Document ID | / |
Family ID | 39469305 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060162679 |
Kind Code |
A1 |
Schnell; Oliver ; et
al. |
July 27, 2006 |
ASSEMBLY AND TORSIONAL STOP DEVICE FOR ROLLER TAPPETS OF A DRIVE IN
AN INTERNAL COMBUSTION ENGINE
Abstract
The invention concerns a mounting and anti-rotation device
(mounting aid) (1) for roller tappets of a valve train of an
internal combustion engine in which gas exchange valves are
activated by roller tappets. The roller tappets comprising a
substantially cylindrical tappet body are retained in receptions
(7, 8) of the mounting aid (1) that is made of plastic. With the
help of opposing parallel anti-rotation surfaces that are arranged
symmetrically to the longitudinal axis of the roller tappet and are
disposed on the end of the tappet body that is oriented away from a
roller, the roller tappets are guided secured against rotation in
the mounting aid during the operation of the internal combustion
engine. This is achieved by the fact that the inner profile of the
receptions (7, 8) is matched to the outer profile of the roller
tappets. To avoid mixing up the switchable with the non-switchable
roller tappets during assembly, the distances between the
anti-rotation surfaces on the different roller tappets, and thus
also the inner contours of the corresponding receptions (7, 8) are
chosen so as to differ markedly from each other. To achieve the
correct orientation of the switchable roller tappets, for example,
relative to an oil gallery, the anti-rotation surfaces of the
switchable roller tappets and the corresponding receptions (8) of
the mounting aid (1) are arranged asymmetrically to the
longitudinal axis of the tappet body and comprise a groove (32) or
a rib (35), respectively.
Inventors: |
Schnell; Oliver;
(Veitsbronn, DE) ; Faria; Christof; (Erlangen,
DE) ; Sailer; Peter; (Erlangen, DE) ; Evans;
Matthew; (Erlangen, DE) |
Correspondence
Address: |
HEDMAN & COSTIGAN P.C.
1185 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
US
|
Family ID: |
39469305 |
Appl. No.: |
10/547056 |
Filed: |
January 16, 2004 |
PCT Filed: |
January 16, 2004 |
PCT NO: |
PCT/EP04/00298 |
371 Date: |
August 25, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60451037 |
Feb 27, 2003 |
|
|
|
Current U.S.
Class: |
123/90.5 ;
123/90.48 |
Current CPC
Class: |
F01L 13/0005 20130101;
F01L 2001/2427 20130101; F01L 2307/00 20200501; F01L 1/181
20130101; F01L 2305/00 20200501; F01L 2301/00 20200501; F01L 1/146
20130101; F01L 1/2422 20130101 |
Class at
Publication: |
123/090.5 ;
123/090.48 |
International
Class: |
F01L 1/14 20060101
F01L001/14 |
Claims
1. A mounting and anti-rotation device for roller tappets of a
valve train of an internal combustion engine comprising at least
two roller tappets comprising a substantially cylindrical tappet
body and a roller mounted at one end to bear against an outer
periphery of a cam of camshaft for being axially displaced by the
cam, said tappet body comprising on an outer peripheral surface at
an upper end oriented away from the roller, a dihedron formed by
two preferably parallel flat surfaces, said mounting and
anti-rotation device (mounting aid) being adapted for attachment to
an engine block and comprising receptions arranged behind one
another for receiving the end of the outer peripheral surface of
the roller tappets oriented away from the roller, an inner profile
of the receptions being matched to an outer profile of the
dihedron, wherein first and second roller tappets comprising
dihedrons having different widths across flats are used, the
dihedrons of one of the first roller tappets or second roller
tappets being configured asymmetric to a longitudinal axis of
respective said tappets and therefore possessing one long and one
short flat surface constituting a long and a short anti-rotation
surface, the mounting aid comprising first and second receptions
that are configured so that the first roller tappets can only be
inserted into the first receptions and the second roller tappets
can only be inserted into the second receptions.
2. A valve train of claim 1, wherein a fixing device of the
mounting aid is arranged outside of a connecting line of center
points of the roller tappets.
3. A valve train of claim 1, wherein one of the short and the long
anti-rotation surfaces of the dihedron configured asymmetric to the
tappet axis comprises a groove and a corresponding one of the
receptions comprises a matching rib, a length of the groove
corresponding at least to a cam lift.
4. A valve train of claim 3, wherein one of the rib and the groove
is arranged in the short anti-rotation surface of the mounting
aid.
5. A valve train of claim 1, wherein every two adjacent receptions
of the mounting aid form a unit and have identical inner
profiles.
6. A valve train of claim 5, wherein the mounting aid comprises at
least two units.
Description
FIELD OF THE INVENTION
[0001] The invention concerns a mounting and anti-rotation device
(mounting aid) for roller tappets of a valve train of an internal
combustion engine comprising at least two roller tappets comprising
a substantially cylindrical tappet body and a roller mounted at one
end to bear against an outer periphery of a cam of camshaft for
being axially displaced by the cam, said tappet body comprising on
an outer peripheral surface at an upper end oriented away from the
roller, a dihedron formed by two preferably parallel flat surfaces,
said mounting and anti-rotation device being adapted for attachment
to an engine block and comprising receptions arranged behind one
another for receiving the end of the outer peripheral surface of
the roller tappets oriented away from the roller, an inner profile
of the receptions being matched to an outer profile of the
dihedron.
[0002] It is general knowledge in the field of internal combustion
engines that the roller tappets of the valve train must be guided
secured against rotation to prevent the roller from moving into a
crosswise position relative to the direction of movement of the cam
of the camshaft and thus prevent increased friction and the
concomitant higher wear and fuel consumption. For this purpose,
heat resistant plastic bridges are used, inter alia, in which the
roller tappets are mounted secured against rotation through
matching inner profiles of the receptions of the bridges and outer
profiles of the roller tappets.
[0003] A generic mounting and anti-rotation device for roller
tappets of a valve train of an internal combustion engine is known
from U.S. Pat. No. 5,088,455 A. This device is made of heat
resistant ceramics or glass fiber reinforced materials and is
designed for attachment to the engine block and for receiving
roller tappets individually in a plurality of receptions arranged
behind one another. The roller tappets are inserted into and
retained by these receptions, so that mounting is facilitated. A
dihedron is arranged on the upper ends of the outer peripheral
surface of the otherwise substantially cylindrical roller tappets.
The receptions of the mounting aid have inner profiles matching
this dihedron. The heights of the anti-rotation surfaces on the
roller tappet and the mounting aid are configured such that the
roller tappet can execute the full cam lift without completely
leaving the mounting aid, so that the mounting aid prevents
rotation of the roller tappet during operation by surface
guidance.
[0004] Taking into account the requirement of reducing fuel
consumption and pollutant emission, some of the cylinders of modern
engines are designed for switching. For this purpose, a mechanism
is required for actuating the gas exchange valves or keeping them
in the closed position depending on the switching state in which
they are. This can be achieved with the help of switchable roller
tappets. Such switchable roller tappets comprise a first portion
that actuates a gas exchange valve through a tappet pushrod and a
rocker arm, and a second portion comprising a roller at a lower end
that cooperates with a cam of a camshaft. The two portions are
arranged concentrically in each other and can be connected to each
other by a coupling device. In the deactivated state, the coupling
device is released and the portion actuated by the cam can move
freely relative to the other portion whereby the actuation of the
gas exchange valve is interrupted. In the active state, the inner
and the outer portions are connected firmly to each other through
the coupling device and the movement of the cam effects an
actuation of the gas exchange valve. The gas exchange valves of the
non-switchable cylinders are driven by non-switchable roller
tappets. A drawback of the prior art discussed above is that,
during assembly, an erroneous association of switchable roller
tappets to non-switchable cylinders and of non-switchable roller
tappets to switchable cylinders is possible.
[0005] A further problem results from the fact that the coupling
mechanism of the switchable roller tappet is hydraulically
operated. For this purpose, a supply of hydraulic fluid to the
coupling device has to be assured. This is realized through an oil
gallery in the crankcase and an opening in the jacket of the roller
tappet. Through this opening, the hydraulic fluid from the oil
gallery is in direct communication with the coupling device and can
thus act thereon. It is not guaranteed that, during assembly, the
switchable roller tappets can be mounted only in that orientation
in which the opening in the tappet jacket is aligned to the oil
gallery.
OBJECTS OF THE INVENTION
[0006] It is an object of the invention to avoid the above
drawbacks and thus provide a mounting and anti-rotation device in
which the non-switchable roller tappets can be associated only to
the cylinders that are not to be switched, the switchable roller
tappets can be associated only to the cylinders that have to be
switched, and in which, in addition, the switchable roller tappets
can be mounted only in that orientation in which the opening in the
outer jacket of the roller tappet is oriented toward the oil
supply.
[0007] This and other objects and advantages of the invention will
become obvious from the following detailed description.
SUMMARY OF THE INVENTION
[0008] The invention achieves the above objects by the fact that
first and second roller tappets comprising dihedrons having
different widths across flats are used, the dihedrons of one of the
first roller tappets or second roller tappets being configured
asymmetric to a longitudinal axis of respective said tappets and
therefore possessing one long and one short anti-rotation surface,
the mounting aid comprising first and second receptions that are
configured so that the first roller tappets can only be inserted
into the first receptions and the second roller tappets can only be
inserted into the second receptions.
[0009] Due to the provision of different widths across flats of the
dihedrons on the outer periphery of switchable and non-switchable
roller tappets to which the inner contours of the respective
receptions of the mounting aid are matched, it is assured that the
roller tappets with the larger width across flats are not mounted
in the receptions for the roller tappets with the smaller width
across flats. Moreover, if roller tappets with the smaller width
across flats are erroneously mounted in the receptions for the
roller tappets with the larger width across flats, the mounting aid
cannot hold them so that they fall out of the holding device during
mounting on the engine block. Thus the error becomes apparent. Due
to the asymmetric arrangement of the anti-rotation surfaces of the
switchable roller tappets and the corresponding receptions of the
mounting aid, it is guaranteed that switchable tappets can be fixed
in the mounting aid only in the orientation in which the opening in
the tappet jacket is aligned to the oil gallery in the cylinder
head. A wrong assembly can thus be avoided in a simple and economic
manner.
[0010] It is further proposed to arrange the fixing device of the
mounting aid outside of the connecting line of the center points of
the roller tappets, so that the mounting aid can be attached to the
crankcase only in the correct orientation.
[0011] In another embodiment of the invention, a groove is arranged
in the long anti-rotation surface of the dihedron on the outer
portion of the switchable roller tappet, and a rib is arranged in
the corresponding portion of the inner space of the mounting aid.
This rib enters into positive engagement with the groove whose
length is chosen so as to enable the execution of the cam lift.
This is a further precautionary measure for assuring correct
mounting orientation of the switchable roller tappet. The mounting
aid being a cast or injected structure made of plastic, it is
advantageous to provide the rib on the mounting aid and the groove
on the outer jacket of the roller tappet because this can be done
economically, for example, in a single stamping operation.
[0012] Alternatively, the groove may be arranged in the short
anti-rotation surface of the dihedron on the outer portion of the
switchable roller tappet and a rib for engaging this groove can be
arranged at a corresponding point in the inner space of the
reception of the mounting aid, the length of the groove being
chosen so as to enable the execution of the cam lift. This is again
a further precautionary measure for assuring correct mounting
orientation of the switchable roller tappet and offers the same
manufacturing advantages as mentioned above.
[0013] According to further propositions of the invention, every
two adjacent receptions for roller tappets that activate gas
exchange valves of the same cylinder have an identical inner
contour, the mounting aid comprises a plurality of pairs of
receptions with an identical inner contour, and the inner contour
of each pair can be different from the inner contour of the other
pairs. This results in an advantageous modular structure that
enables a plurality of roller tappets of different designs to be
mounted correctly and in a single work step.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Further features and advantages of the invention will become
obvious from the following description and the appended drawings in
which an example of embodiment is illustrated in a simple form.
[0015] FIG. 1 is a side view of a mounting aid comprising
switchable and non-switchable roller tappets, including a partial
sectional view of the region of a fixing device;
[0016] FIG. 2 is a top view of the mounting aid of FIG. 1;
[0017] FIG. 3 shows a longitudinal section through a switchable
roller tappet;
[0018] FIG. 4 shows a partial longitudinal section of the roller
tappet of FIG. 3, offset at 90.degree. ;
[0019] FIG. 5 shows a partial sectional view of an internal
combustion engine comprising a switchable roller tappet;
[0020] FIG. 6a is a top view of a non-switchable roller tappet;
[0021] FIG. 6b is a top view of a switchable roller tappet;
[0022] FIG. 7 shows a cross-section along line VII-VII of FIG. 1
through the mounting aid having an inserted, non-switchable roller
tappet;
[0023] FIG. 8 shows a cross-section along ling VIII-VIII of FIG. 1
through the mounting aid having an inserted, switchable roller
tappet.
DETAILED DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 shows a mounting aid 1 of the invention comprising a
fixing device 2 for fixing to a crankcase, not shown. The mounting
aid 1 receives two non-switchable roller tappets 3 and two
switchable roller tappets 4. Each roller tappet 3, 4 comprises a
roller 5 and is mounted through a roller-distal end portion in the
mounting aid 1. The roller tappets 4 that are switchable comprise,
for this purpose, an opening 6 through which a pressure medium can
be supplied. The roller tappets 3, 4 are inserted into reception
openings 7, 8 (FIG. 2). Further, in the region of the fixing device
2, the mounting aid 1 has an asymmetric configuration with respect
to its center point to prevent a wrongly oriented attachment of the
mounting aid 1 to the crankcase.
[0025] A switchable roller tappet 4 is illustrated in FIGS. 3 and
4. This tappet substantially comprises an outer cylindrical portion
9 that receives a piston element 11 in its cylindrical reception
10. In addition, a coupling element 12 is arranged in a bore 13 in
the lower end of the piston element 11. FIGS. 3 and 4 further show
a valve lash adjuster 14 in the piston element 11 and a spring
assembly 15 in the outer portion 9, said spring assembly serving to
displace the piston element 11 into an end position. In the
uncoupled state, the two components 9 and 11 are axially
displaceable relative to each other. With the help of the coupling
element 12, the outer portion 9 and the piston element 11 can be
positively connected to each other. The coupling element 12 is
displaced into the coupling position by a spring means 16
configured, in the present embodiment, as a coil spring. At its end
oriented away from the coupling element 12, the spring means 16 is
supported on an anti-rotation peg 17. This anti-rotation peg 17 is
guided in a slot 18 of the cylindrical portion 9. The connection
between the outer portion 9 and the piston element 11 can be
released by applying a counter pressure to an end face 19 of the
coupling element 12 through a hydraulic fluid.
[0026] FIG. 5 shows a longitudinal section through an internal
combustion engine in which a switchable roller tappet 4 is axially
displaced by a cam 20 of a camshaft 21. The longitudinal motion of
the roller tappet 4 is transmitted through a tappet pushrod 22 and
a rocker arm 23 to a gas exchange valve 24. To release the rigid
connection between the outer portion 9 and the piston element 11,
the counter pressure on the end face 19 of the coupling element 12
can be built up through an oil gallery 25 that communicates with
the end face 19 through the opening 6 on the outer jacket of the
switchable roller tappet 4. As a person skilled in the art will
readily see from FIG. 5, the switchable roller tappet 4 can only
perform its function if it is inserted in the correct orientation
into its reception 8 to assure that the opening 6 of the outer
cylindrical portion 9 is aligned to the oil gallery 25. This is
achieved through the profiling of the outer cylindrical portion 9
of the switchable roller tappet 4 or the tappet body 26 of the
non-switchable roller tappet 3 at the end of the roller tappets
oriented away from the roller 5.
[0027] FIG. 6a shows the end of the non-switchable roller tappet 3
oriented away from the roller 5 in a top view. The substantially
cylindrical tappet body comprises two opposing, parallel
anti-rotation surfaces 27 that form a dihedron 28. The dihedron 28
is arranged symmetrically to the tappet axis. As can be seen in
FIG. 6b, the switchable roller tappet 4 also comprises two
anti-rotation surfaces 29, 30 that form a dihedron 31. The width
across flats of the dihedron 28 is markedly different from the
width across flats of the dihedron 31. Moreover, the anti-rotation
surfaces 29, 30 are arranged asymmetrically to the longitudinal
axis of the roller tappet body and thus form a short anti-rotation
surface 29 and a long anti-rotation surface 30. The short
anti-rotation surface 29 comprises a groove 32.
[0028] The inner contours of the receptions 7, 8 of the
non-switchable and switchable roller tappets 3, 4 comprise circular
portions 33 and chord-like portions 34 and are matched to the outer
contours of the respective roller tappets. In addition, the inner
contour of each reception 8 for the switchable roller tappets 4
comprises a rib 35 that engages the groove 32 of the short
anti-rotation surface 29 of the switchable roller tappet 4.
[0029] The roller tappets are inserted into and held in the
receptions 7, 8 through their ends oriented away from the roller 5.
As disclosed in FIGS. 7, 8, the anti-rotation surfaces 27, 29, 30
of the roller tappets 3, 4 assure, in cooperation with the
chord-like portions 34 of the receptions 7, 8 of the mounting aid
1, that the roller tappets 3, 4 are guided secured against rotation
during the operation of the internal combustion engine. These
structures further assure that the switchable roller tappets 4 are
not inserted into the receptions 7 for the non-switchable roller
tappets 3, and vice versa. As a person skilled in the art will
readily see from FIGS. 7, 8, these contours also prevent the
switchable roller tappets 4 comprising the dihedron 31 with the
larger width across flats from being erroneously inserted into the
receptions 7 that are intended for the non-switchable roller
tappets 3 comprising the dihedron 28 with the smaller width across
flats. On the other hand, a non-switchable roller tappet 3 having
the smaller dihedron width across flats, if erroneously inserted
into a reception 8 of the switchable roller tappet 4 having the
larger dihedron width across flats, would fall out when the
mounting aid 1 is fixed to the crankcase, so that the error will
become apparent. The eccentrically arranged anti-rotation surfaces
29, 30 of the switchable roller tappet 4, as also the groove 32 in
the shorter anti-rotation surface 29 in cooperation with the rib 35
of the reception 8 of the mounting aid 1, guarantee that the
switchable roller tappet 4 can only be inserted in the correct
orientation.
* * * * *