U.S. patent application number 14/434506 was filed with the patent office on 2015-10-01 for valve, in particular for an internal combustion engine.
This patent application is currently assigned to Valeo Systemes de Controle Moteur. The applicant listed for this patent is VALEO SYSTEMES DE CONTROLE MOTEUR. Invention is credited to David Cravo, Gregory Hodebourg, Nicolas Martin.
Application Number | 20150275709 14/434506 |
Document ID | / |
Family ID | 47425088 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150275709 |
Kind Code |
A1 |
Hodebourg; Gregory ; et
al. |
October 1, 2015 |
VALVE, IN PARTICULAR FOR AN INTERNAL COMBUSTION ENGINE
Abstract
A valve (1), in particular for a combustion engine,
comprising:--a body (2) in which the following are provided: a
housing (8) in which at least one bearing is arranged, and a
conduit (3) designed to be traversed by a fluid, and--a shutter (5)
mounted pivoting in the body (2) by a pin (7) received with radial
clearance in the bearing, the shutter (5) pivoting between:--an
open position, and--a closed position in which it comes into
contact with the body (2) via a first contact area of the shutter
located on a first side of the pin (7) and via a second contact
area of the shutter located on a second side of the pin (7)
opposite said first side, the switching of the shutter (5) from the
open position to the closed position being accompanied by a radial
movement of the pin (7) in the bearing.
Inventors: |
Hodebourg; Gregory;
(Sartrouville, FR) ; Martin; Nicolas;
(Maisonslafitte, FR) ; Cravo; David; (Osny,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VALEO SYSTEMES DE CONTROLE MOTEUR |
Cergy Saint Christophe |
|
FR |
|
|
Assignee: |
Valeo Systemes de Controle
Moteur
Cergy Saint Christophe
FR
|
Family ID: |
47425088 |
Appl. No.: |
14/434506 |
Filed: |
October 7, 2013 |
PCT Filed: |
October 7, 2013 |
PCT NO: |
PCT/FR2013/052380 |
371 Date: |
April 9, 2015 |
Current U.S.
Class: |
123/188.1 |
Current CPC
Class: |
F16K 11/052 20130101;
F02M 26/70 20160201; F16K 1/2028 20130101; F01L 3/00 20130101 |
International
Class: |
F01L 3/00 20060101
F01L003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2012 |
FR |
1259688 |
Claims
1. A valve for an internal combustion engine, comprising: a body
including: a housing in which is disposed at least one bearing and
a duct adapted to have a fluid pass through it, and a shutter
mounted to pivot in the body by means of a pin received with radial
play in the bearing, the shutter (5) pivoting between: an open
position, and a closed position in which the shutter comes into
contact with the body in a first contact area of the shutter on a
first side of the pin and in a second contact area of the shutter
on a second side of the pin opposite said first side, the passage
of the shutter from the open position to the closed position being
accompanied by radial movement of the pin in the bearing.
2. The valve as claimed in claim 1, wherein the valve lacks any
flexible element disposed between the shutter and the body when the
shutter is in the closed position.
3. The valve as claimed in claim 1, wherein the shutter and the pin
are connected by a support extending along at least a portion of
the pin.
4. The valve as claimed in claim 1, the body having a sealing plane
of the body coming into contact with the first contact area and/or
the second contact area of the shutter when the shutter in the
closed position and the first contact area and/or the second
contact area of the shutter being in a sealing plane of the
shutter.
5. The valve as claimed in claim 4, wherein the distance between
the center of the housing and the sealing plane of the body is
greater than the distance between the center of the pin and the
sealing plane of the shutter.
6. The valve as claimed in claim 4, wherein the distance between
the center of the housing and the sealing plane of the body is less
than the distance between the center of the pin and sealing plane
of the shutter.
7. The valve as claimed in claim 1, wherein the first contact area
and/or the second contact area of the shutter form a line contact
with the body when the shutter is in the closed position.
8. The valve as claimed in claim 7, wherein the shutter has a
rectangular shape and the first contact area and the second contact
area being on opposite sides of the shutter.
9. The valve as claimed in claim 7, wherein only the first contact
area of the shutter is in the sealing plane of the shutter, the
second contact area of the shutter being in another plane of the
shutter.
10. The valve as claimed in claim 9, the sealing plane of the
shutter and said other plane of the shutter being on opposite faces
of the shutter.
11. The valve as claimed in claim 1, wherein the first contact area
and/or the second contact area of the shutter form a plane contact
with the sealing plane of the body when the shutter is in the
closed position.
12. The valve according to claim 11, wherein the first contact area
and the second contact area of the shutter are in the sealing plane
of the shutter and each of said contact areas of the shutter
contacts the sealing plane of the body when the shutter is in the
closed position.
13. The valve as claimed in claim 11, the first contact area of the
shutter being on a first part of the shutter and on the upper face
of said first part, the second contact area of the shutter being on
a second part of the shutter and on the lower face of said second
part.
14. The valve as claimed in claim 13, wherein the first part and
the second part are rigidly coupled to each other to form the
shutter in the sealing plane of the shutter.
15. The valve as claimed in claim 13, wherein the length of the
second part of the shutter measured along the pin is less than the
length of the first part of the shutter measured along the pin.
16. The valve as claimed in claim 4, the sealing plane of the
shutter being a plane other than a plane intersecting the pin.
17. The valve as claimed in claim 1, wherein the valve is a
three-port valve, and each of the open and closed positions
comprise an extreme position for the pivoting of the shutter.
Description
[0001] The present invention concerns a valve, in particular for an
internal combustion engine.
[0002] The invention in particular applies when the internal
combustion engine is used for the propulsion of a vehicle, for
example a motor vehicle. It may be an engine the fuel of which is
petrol or diesel. The valve may be integrated into the air circuit
of the internal combustion engine.
[0003] In the context of the invention, the "internal combustion
engine air circuit" means the circuit between the admission inlet
and the exhaust outlet of the internal combustion engine. The valve
may be in the admission circuit, the exhaust circuit, or a
recirculation loop through which exhaust gas recirculation (EGR)
gases pass.
[0004] In the case of a valve including: [0005] a body including a
duct in which a fluid flows, and [0006] a shutter mounted to be
mobile in the body between an open position and a closed position
in which it has to block the duct, there are problems of the valve
leaking when the shutter is in the closed position. To solve these
problems, it is known to use a seal that is disposed between the
body and the shutter when the latter is in the closed position.
However, a seal of this kind is liable to expand because of the
high temperatures that can be reached in its environment.
[0007] Another solution to this problem linked to the use of a seal
is to bring the shutter directly into contact with the body when
the shutter is in the closed position. However, a dimensional
constraint between the shutter and the part of the duct in which it
moves must be complied with to prevent the shutter from being
wedged against the wall of said part of the duct before reaching
the closed position, as is described hereinafter with references to
FIGS. 24 and 25.
[0008] In those figures, the body 102 has a sealing plane P coming
into contact with a sealing plane P' of the shutter 105 when the
shutter is in the closed position to block the duct 103 in the body
102. Because of the rigid nature of the contacts between the
shutter and the body, it is found that the shutter 105 is prevented
from being wedged against the wall of the body 102 if the distance
Dv measured between the center of the pin 107 enabling the shutter
105 to pivot in the body 102 and the sealing plane P' of the
shutter 105 is less than or equal to the distance Dc measured
between the center of the housing 108 of the body 102 in which the
pin 107 is received and the sealing plane P of the body 102.
[0009] This dimensional constraint must further be weighted to
allow for inaccuracies in respect of the dimensions of the various
components of the valve during manufacture thereof. Because of this
weighting, there may be relatively large empty sections between the
body and the shutter when the shutter is in the closed position,
these empty sections, also known as "leakage sections", potentially
causing leaks greater than what can be tolerated when the valve is
in the closed position.
[0010] There exists a requirement for a valve that is relatively
simple to manufacture and effectively overcomes the disadvantages
referred to above.
[0011] An object of the invention is to address this requirement
and, in one of its aspects, it does so by means of a valve, in
particular for an internal combustion engine, comprising: [0012] a
body including: a housing in which is disposed at least one bearing
and a duct adapted to have a fluid pass through it, and [0013] a
shutter mounted to pivot in the body by means of a pin received
with radial play in the bearing, the shutter pivoting between:
[0014] an open position, and [0015] a closed position in which it
comes into contact with the body in a first contact area of the
shutter on a first side of the pin and in a second contact area of
the shutter on a second side of the pin opposite said first side,
the passage of the shutter from the open position to the closed
position being accompanied by radial movement of the pin in the
bearing.
[0016] The above valve makes it possible to prevent the shutter
from being wedged against the wall of the duct when the shutter
goes to the closed position without it being necessary to comply
with any excessive dimensional constraint between the shutter and
the part of the duct in which it moves.
[0017] This dimensional constraint is reduced thanks to the use of
the play of the bearing(s), which constitutes an adjustment
variable with regard to inaccuracies in the dimensions of the
various components of the valve during manufacture thereof.
[0018] The shutter is preferably not directly in contact with the
body when it is in the open position.
[0019] When it moves, the shutter may be in a single closed
position, in which it comes into contact with the body. The valve
may be a valve in the admission circuit of the internal combustion
engine, in the exhaust circuit of the internal combustion engine,
or in an exhaust gas recirculation loop enabling the latter gases
to be re-injected into the admission side of the internal
combustion engine. This recirculation loop may be a "low-pressure"
loop or a "high-pressure" loop.
[0020] The valve is in particular a so-called "two-port" valve.
[0021] Alternatively, the valve may be a so-called "three-port"
valve. The valve may then be at the inlet of the recirculation
loop, that is to say at the place in the exhaust circuit at which
the recirculation loop starts. The so-called "three-port" valve may
alternatively be at the outlet of the recirculation loop, that is
to say at the place in the admission circuit where the exhaust
gases are re-injected into the admission side.
[0022] The valve may therefore be at most a three-port valve.
[0023] The closed position, in which the shutter blocks the duct,
and the open position may each be an extreme position for the
pivoting of the shutter. In other words, the pivoting of the
shutter between the open position and the closed position defines
the maximum amplitude of the movement in rotation of the
shutter.
[0024] There is advantageously no flexible element of the valve
between the shutter and the body when the shutter is in the closed
position. Here "flexible" is used in contrast to "rigid", the body
and the shutter then being rigid.
[0025] A flexible element of this kind is a seal, for example. The
shutter and the pin may be connected by a support extending along
at least a portion of the pin. The pin and the shutter may be in
different planes.
[0026] The valve therefore has a pin offset relative to the
shutter, in contrast to valves in which the pin and the shutter are
in the same plane.
[0027] Alternatively, the pin and the shutter may be in the same
plane.
[0028] The body may have a sealing plane of the body coming into
contact with the first and/or second contact area of the shutter
when the shutter is in the closed position and the first and/or the
second contact area of the shutter may be in a sealing plane of the
shutter.
[0029] The first contact area of the shutter may be in a sealing
plane of the shutter other than a plane intersecting the axis.
[0030] The second contact area of the shutter may be in another
sealing plane of the shutter other than a plane intersecting the
axis.
[0031] When the shutter is in the closed position, the sealing
plane of the body and the sealing plane of the shutter have at
least one point of contact. The radial play of the bearing(s) may
distance a portion of the shutter from the sealing plane of the
body when the shutter goes to the closed position.
[0032] The distance between the center of the housing and the
sealing plane of the body may be greater than the distance between
the center of the pin and the sealing plane of the shutter. This
dimensional constraint, which is generally imposed, makes it
possible to prevent the shutter from being wedged against the wall
of the duct when the shutter goes to the closed position. If this
constraint is complied with, no play in the bearing is necessary to
prevent the shutter from being wedged against the wall of the duct.
The second area of contact of the shutter against the body can make
it possible to prevent excessive movement of the pin in the bearing
and thus to prevent excessively large leakage sections existing
when the shutter is in the closed position. This therefore reduces
the use of the radial play available in the bearing(s), given that
the movement of the shutter because this play to prevent wedging is
then not necessary.
[0033] Alternatively, the distance between the center of the
housing and the sealing plane of the body may be less than the
distance between the center of the pin and the sealing plane of the
shutter. This situation can arise even though an attempt has been
made to comply with the above dimensional constraint, because of
inaccuracies in the dimensions of the components of the valve
during manufacture thereof. If no play of the bearing(s) is used,
this situation leads to wedging of the shutter against the wall of
the duct when the shutter goes to the closed position, which
normally prevents the use of any such valve. Using the play in the
bearing(s) makes it possible to revert to the previous situation in
which there is no wedging.
[0034] Thus the invention can make it possible nevertheless to use
valves in which, for reasons of inaccuracies in the dimensions of
the components of the valve during manufacture thereof, the above
dimensional constraint between the shutter and the wall of the body
in which it moves are not complied with.
[0035] The play in the bearing(s) may be sized to be greater than
or equal to a predefined overall inaccuracy for the shutter and the
part of the duct in which the shutter moves, this predefined
overall inaccuracy resulting in particular from the linear
combination of predefined individual inaccuracy for each side of
the shutter and the part of the duct in which the shutter moves.
Each predefined overall inaccuracy is for example fixed as a
function of feedback in respect of the technique used to
manufacture the corresponding component of the valve.
[0036] The predefined overall inaccuracy may be obtained by adding
the predefined individual inaccuracies for the following
dimensions: [0037] distance between the center of the housing and
the sealing plane of the body, [0038] distance between the center
of the pin and the sealing plane of the shutter, [0039] thickness
of the shutter, [0040] height of a groove in the duct, one part of
the shutter in which the second area of contact is situated in the
closed position moving in this groove when the shutter goes from
the open position to the closed position.
[0041] In accordance with a first embodiment of the invention, the
first and/or second contact area of the shutter forms a line
contact with the body when the shutter is in the closed
position.
[0042] Each contact area of the shutter may form a line contact
with the body when the shutter is in the closed position.
[0043] In accordance with this first embodiment of the invention,
only the first contact area of the shutter can come into contact
with the sealing plane of the body when the shutter is in the
closed position. The second contact area of the shutter may be in
another plane of the shutter and come into contact with the body
elsewhere than in the sealing plane of the body when the shutter is
in the closed position. The sealing plane of the shutter and this
other plane of the shutter may then be parts of opposite faces of
the shutter, the latter in particular taking the form of a
plate.
[0044] The shutter may have a rectangular shape in section, the
first contact area and the second contact area being on opposite
sides of the shutter.
[0045] Alternatively, the shutter may have a half-moon shape in
section the diameter of which is extended by a rectangle and the
first area of contact may be on the circle of the half-moon and the
second contact area carried by the side of the rectangle opposite
the side of the rectangle coinciding with the diameter of the
half-moon.
[0046] When the part of the shutter carrying the second contact
area in the closed position moves in a groove in the body and
forming part of the duct, the second contact area can then contact
the bottom of the groove formed by said other plane.
[0047] In accordance with a second embodiment of the invention, the
first and/or second contact area of the shutter may form a plane
contact with the sealing plane of the body when the shutter is in
the closed position.
[0048] For example, each contact area of the shutter forms a plane
contact with the sealing plane of the body when the shutter is in
the closed position.
[0049] The first and second contact areas of the shutter may be in
the sealing plane of the shutter and each of said contact areas of
the shutter then contacts the sealing plane of the body when the
shutter is in the closed position. The shutter may then be a
self-centering shutter, by virtue of the fact that the contacts
between the shutter and the body occur in a single plane when the
shutter is in the closed position and radial play exists in the
bearing(s). With such a valve, when the shutter is in the closed
position, the contacts between the shutter and the body can enable
immobilization of the pin without the latter being in contact with
the bearing(s).
[0050] The sealing plane of the shutter may a plane other than a
plane intersecting the pin.
[0051] In accordance with this second embodiment of the invention,
the first contact area of the shutter may be carried by a first
part of the shutter and be part of the upper face of said first
part and the second contact area of the shutter may be carried by a
second part of the shutter and be part of the lower face of said
second part. In other words, in accordance with this second
embodiment of the invention, the first and second contact areas may
be parts of opposite faces of the shutter whilst being in the same
plane.
[0052] Each of the first and second parts may be a separate part,
said parts being rigidly coupled to each other to form the shutter.
Each of these parts is a plate, for example. Said parts are in
particular rigidly coupled to each other at the level of the
sealing plane of the shutter.
[0053] In accordance with this second embodiment of the invention,
the part of the duct in which the shutter moves may be formed in
two parts of the body rigidly coupled to each other at the level of
the sealing plane of the body. Part of the sealing plane of the
body may be defined by the upper face of one of these parts of the
body, which then comes into contact with the part of the lower face
of the second part of the shutter forming the second contact area
when the shutter is in the closed position whereas another part of
the sealing plane of the body may be defined by the lower face of
another part of the body which then comes into contact with the
part of the upper face of the first part of the shutter forming the
first contact area when the shutter is in the closed position.
[0054] In accordance with the second embodiment of the invention,
the length of the second part of the shutter measured along the pin
may be less than the length of the first part of the shutter
measured along the pin. The shutter is then formed by two parts of
different length and the length of the first part can be such that
in the closed position no leakage occurs at the level of this first
part and only the second part causes leaks.
[0055] The invention may be better understood by reading the
following description of nonlimiting embodiments thereof and
examining the appended drawings, in which:
[0056] FIGS. 1 to 11 relate to a valve in accordance with a first
embodiment of the invention, FIGS. 1 and 2 representing the valve
in elevation, FIG. 3 representing the shutter and the pin
separately, FIG. 4 being a plan view of the valve from FIG. 1,
FIGS. 5 to 7 representing in section taken along the line A-A a
first valve similar to that from FIG. 4, FIGS. 8 to 10 representing
in section taken along the line A-A a second valve similar to that
from FIG. 4, and FIG. 11 diagrammatically representing a valve in
accordance with the first embodiment of the invention when it is of
the "three-port" type,
[0057] FIGS. 12 to 23 relate to a valve in accordance with a second
embodiment of the invention, FIGS. 12 and 13 representing the valve
in elevation, FIG. 14 representing the shutter and the pin
separately, FIG. 15 being a plan view of the valve from FIG. 12,
FIGS. 16 to 18 representing in section taken along the lines A-A,
B-B and C-C a first valve similar to that from FIG. 15, FIGS. 19 to
21 representing in section taken along the lines A-A, B-B and C-C a
second valve similar to that from FIG. 15, FIG. 22 representing the
valve from FIG. 15 in an exaggerated manner,
[0058] FIG. 23 diagrammatically representing a valve in accordance
with the second embodiment of the invention when it is of the
"three-port" type, and
[0059] FIGS. 24 and 25 have already been described.
[0060] There has been represented in FIG. 1 a valve 1 covered by
the invention. In this figure the valve 1 is a so-called "two-port"
valve but the invention is not limited thereto, as emerges
hereinafter.
[0061] The valve 1 that is to be described is a valve used in an
air circuit of an internal combustion engine, used for example to
propel a motor vehicle.
[0062] The valve 1 includes a body 2, for example made from
aluminum, steel, plastic or stainless steel, in which is formed a
duct 3. This is for example an admission duct, an exhaust duct or a
duct forming an exhaust gas recirculation (EGR) loop, which can be
a high-pressure loop or a low-pressure loop. The body 2 of the
valve may be made by assembling two parts 2a and 2b, these two
parts being in contact on a plane P of which one wall defines a
part of the duct 3, as emerges hereinafter. The plane P is referred
to as the "sealing plane" of the body 2 hereinafter. The part 2b
has not represented in FIG. 2.
[0063] In the example considered gases that can reach a high
temperature, for example up to 700.degree. C., pass through the
duct 3.
[0064] As represented in FIGS. 1 and 2, the valve 1 includes a
shutter 5 disposed in the body and mounted to pivot thanks to a pin
7 received in a housing 8 of the body 2 by means of one or more
bearings that are not represented. The pin 7 extends in a direction
X and the bearing(s) have radial play in the direction X allowing
the pin 7 to move in the bearing and in the housing 8
perpendicularly to the direction X. FIG. 3 represents the shutter 5
and the pin 7 separately. As can be seen in FIG. 3, the shutter can
take the form of a cylinder of circular cross section. In the
example described a support 9 extending radially relative to the
pin 7 connects the pin 7 and the shutter 5.
[0065] In the FIG. 3 example, the shutter 5 is globally plane and
perpendicular to the direction of the support 9.
[0066] As emerges hereinafter, the shutter 5 has two areas 11 and
12 of contact with the body 2 when it is the closed position. The
first contact area 11 is on a first side of the pin 7, that is to
say a first side of the support 9 here and the second contact area
12 is on a second side of the pin 7, that is to say a second side
of the support 9 here. The second contact area 12 is carried by a
portion of the shutter moving in a groove 13 formed in the duct 3.
Here the second contact area 12 comes into contact with the bottom
of the groove 13.
[0067] The distance between the center of the housing 8 and the
sealing plane P of the body 2 is designated "Dc". In the example
shown in FIGS. 1 to 11, the upper face of the shutter 5 defines a
joint plane P' of the shutter 5, as explained hereinafter, and the
distance between the center of the pin 7 and this plane P is
designated "Dv".
[0068] In the example shown in FIGS. 5 to 7, the distance Dc is
less than Dv, that is to say the sealing plane P' of the shutter is
farther from the sealing plane P of the body from the pin 7. In the
prior art, such a configuration, which can be explained by the
margins of error in respect of the dimensions of the various
components of the valve 1 during manufacture thereof, prevents the
shutter 5 from reaching its closed position, the shutter being
wedged against the wall of the duct 3 before it can reach the
closed position.
[0069] In FIG. 5, the shutter 5 is still in the open position and
gases can circulate in the duct 3 and through the valve 1. Here the
shutter 5 is not in contact with the body 2, neither the first
contact area 11 nor the second contact area 12 coming into contact
with the body 2.
[0070] In FIG. 6, the shutter 5 is moving toward the closed
position by pivoting of the pin 7 in the housing 8. Contact is then
established between the shutter 5 and the body 2 of the valve
1.
[0071] As can be seen in FIG. 7, in contrast to the prior art
valves, the fact that the sealing plane P' of the shutter 5 is
farther than the sealing plane P of the body 2 from the pin 7 does
not prevent the shutter 5 from reaching a closed position in which
it comes into contact with the body 2 in two separate areas 11 and
12. In fact, as represented in FIG. 7, because of the closing
torque applied to the shutter by an actuator that is not
represented, the pin 7 moves radially relative to the direction X
in the housing 8, with the result that the positions relative to
the pin 7 of the sealing plane P' of the shutter 5 and the sealing
plane P of the body 2 are modified and the contact that can be seen
in FIG. 6 between the shutter 5 and the body does not prevent the
shutter 5 from continuing to move toward the closed position.
[0072] In this example the shutter comes into contact with two
separate walls of the duct 3. In this first embodiment of the
invention only the first contact area 11 is in the sealing plane P'
of the shutter 5 and in this embodiment only this first contact
area 11 comes into contact with the sealing plane P of the body
2.
[0073] In this embodiment there is therefore only one area of
contact between the sealing plane P of the body 2 and the sealing
plane P' of the shutter 5.
[0074] Here the second contact area 12 is in a plane parallel to
the sealing plane P' of the shutter 5 and defining the face of the
shutter 5 opposite that formed by the sealing plane P'.
[0075] The play in the bearing(s) making it possible to prevent the
shutter 5 from being wedged against the wall of the body 2 when the
shutter 5 goes to the closed position is determined taking into
account the inaccuracies in respect of the following dimensions,
for example: [0076] distance Dv, [0077] distance Dc, [0078]
thickness e of the shutter 5 in the second contact area 12, [0079]
height h of the groove 13.
[0080] In this example the play in the bearings is chosen to
prevent wedging of the shutter 5 in the following extreme cases
because of the dimensional inaccuracies: [0081] (i) maximum Dc,
minimum Dv, maximum h and minimum e, corresponding to potential
interference at the top of the bearings, [0082] (ii) minimum Dc,
maximum Dv, minimum h and maximum e, corresponding to potential
interference at the bottom of the bearings.
[0083] Four dimensions may be taken into account for the distance
Dv, i.e. four individual levels of inaccuracy to be defined: [0084]
the straightness of the pin 7, for which an individual level of
inaccuracy of 0.02 mm in respect of the diameter of the pin 7 is
set, for example, [0085] the position of the driving flats on the
pin 7, for which an individual level of inaccuracy of 0.1 mm is
set, for example, [0086] the position of the driving flats on the
pin 5, for which an individual level of inaccuracy of 0.04 mm is
set, for example, and [0087] the position of the sealing plane P'
of the shutter 5, for which an individual level of inaccuracy of
0.04 mm is set, for example.
[0088] Two dimensions are to be taken into account for the distance
Dc, i.e. two individual levels of inaccuracy to be defined: [0089]
the position of the sealing plane P of the body 2, for which an
individual level of inaccuracy of 0.1 mm is set, for example, and
[0090] the coaxial relationship of the bearings, for which a level
of inaccuracy of 0.04 mm in respect of the diameter of the bearings
is set, for example.
[0091] There is therefore a variation of .+-.0.10 mm in Dv and
.+-.0.07 mm in Dc.
[0092] In the extreme case (i), the compensation of play available
in the upward direction must be at least (+0.07)-(-0.1)=0.17 mm in
the example considered.
[0093] In the extreme case (ii), the compensation of play available
in the downward direction must be at least (-0.07)-(+0.1)=-0.17
mm.
[0094] A predefined overall error margin of 0.34 mm is therefore
obtained, as a result of which the bearings are sized so that each
of them offers at least 0.34/2 mm, i.e. 0.17 mm, of radial play in
this example.
[0095] FIGS. 8 to 10 also represent the valve 1 when the shutter 5
goes from the open position to the closed position. In contrast to
the example that has just been described, the distance Dc is
greater than the distance Dv, that is to say the sealing plane P'
of the shutter is nearer the pin 7 than the sealing plane P of the
body. In this case, in contrast to the previous case, it is not
necessary to modify the relative positions of the sealing plane P'
of the shutter 5 and the sealing plane P of the body 2 relative to
the pin 7 to enable the shutter 5 to reach the closed position.
[0096] The second contact area 12, on the side of the pin 7
opposite the side bearing the first contact area 11, makes it
possible to prevent excessive radial movement of the pin 7 in the
housing 8. The second contact area in fact comes to bear against
the bottom of the groove 13, preventing further movement of the pin
7 in the bearing because of the closing torque applied by the valve
actuator. This therefore prevents serious leaks when the shutter 5
is in the closed position because of this movement linked to the
existence of the radial play in the bearings.
[0097] In accordance with this first embodiment of the invention,
when the shutter is in the closed position the shutter 5 forms a
line contact with the body 2 in the first contact area 11 and in
the second contact area 12.
[0098] The embodiments shown FIGS. 1 to 10 relate to a so-called
"two-port" valve. However, the first embodiment of the invention
also covers so-called "three-port" valves, as FIG. 11 shows. In
this figure, the duct 3 comprises an inlet 20, a first outlet 21
and a second outlet 22. For example, the first outlet 21 allows the
gases circulating in the exhaust circuit to continue their path in
the latter and the second outlet 22 opens into a recirculation loop
to the admission side of the engine. In this example, the shutter 5
of the valve 1 from FIGS. 1 to 10 has an extension 24 extending
beyond the part of the shutter 5 including the second area 12, so
that the latter is disposed between said extension 24 and the part
of the shutter including the first area 11.
[0099] In FIG. 11, the shutter 5 is in a position in which the
exhaust gases recirculate in the EGR loop. The extension 24
partially blocks the passage toward the first outlet 21, in order
to create a back-pressure for maintaining sufficient pressure on
the upstream side of the valve 5 to enable a high flow rate toward
the second outlet 22.
[0100] A valve 1 in accordance with a second embodiment of the
invention is described next with reference to FIGS. 12 to 22.
[0101] FIGS. 12 to 15 are similar to FIGS. 1 to 4. In accordance
with this second embodiment, the shutter 5 comprises two portions
30 and 31 formed by separate parts fastened together. Each of these
parts is in the form of a plate and the upper face 32 of the plate
30 lies against the lower face 33 of the plate 31 without these
plates 30 and 31 being exactly superposed. In this example, the
upper face 32 of the plate 30 and the lower face 33 of the plate 31
are coplanar and be in the sealing plane P' of the shutter 5. The
sealing plane P of the body 2 is similar to that described with
reference to the first embodiment of the invention. Screws 35 are
used to fix the plate 31 to the plate 30, for example.
[0102] In the embodiment represented the plate 30 is nearer the pin
7 than the plate 31 and here the plate 30 is connected to the
support 9.
[0103] Here the upper face of the shutter 5 is defined by the
portion of the upper face 32 of the plate 30 not facing the plate
31 and by the upper face of the plate 31 and the lower face of the
shutter 5 is defined by the lower face of the plate 30 and by the
portion of the lower face 33 of the plate 31 not facing the plate
30.
[0104] Still in this embodiment, and as can be seen in FIG. 14, the
length l1 of the plate 30 as measured in the direction X is greater
than the length l2 of the plate 31.
[0105] In accordance with this second embodiment of the invention,
the two parts 2a and 2b of the body are rigidly coupled to each
other at the level of the sealing plane P of the body 2.
[0106] FIGS. 16 through 18 each represent three views in section of
a position of the shutter 5 when Dv is greater than Dc.
[0107] In FIG. 16, the shutter 5 is in the open position and is not
in contact with the body 2. In FIG. 17, the shutter 5 is going from
the open position toward the closed position and the upper face 32
of the plate 31 is on the point of coming into contact with the
sealing plane P of the body 2, this contact causing wedging of the
shutter 5 in the duct 3 in the prior art.
[0108] As can be seen in FIG. 17, thanks to the radial play in the
bearing(s), the pin 7 is able to move radially, allowing the plate
30 to move away from the sealing plane P of the body 2. The shutter
5 can continue its movement until it reaches the closed position in
which it comes into contact with the sealing plane P of the body 2
via the first area 11 and the second area 12. Here the first area
11 is on the upper face 32 of the plate 30 and the second area 12
is on the lower face 33 of the plate 31. The first area 11 and the
second area 12 are therefore in the same plane, namely the sealing
plane P' of the shutter 5. Here the contact between the shutter 5
and the body 2 via the first and second areas 11 and 12 is plane,
occurring exclusively between the respective sealing planes P and
P'.
[0109] For example, the play in the bearing(s) for preventing the
shutter 5 from being wedged against the wall of the body 2 when the
shutter 5 goes to the closed position is determined in accordance
with this second embodiment of the invention by taking into account
the inaccuracies in respect of the following dimensions: [0110]
distance Dv, and [0111] distance Dc.
[0112] In this embodiment the play in the bearings is chosen so
that it prevents wedging of the shutter 5 in the following extreme
cases resulting from dimensional inaccuracies: [0113] (i) maximum
Dc, minimum Dv, corresponding to potential interference at the top
of the bearings, [0114] (ii) minimum Dc, maximum Dv, corresponding
to potential interference at the bottom of the bearings.
[0115] Four dimensions are to be taken into account for the
distance Dv, i.e. four individual levels of inaccuracy to be
defined: [0116] the straightness of the axis 7, for which an
individual level of inaccuracy of 0.02 mm in respect of the
diameter of the pin 7 is set, for example, [0117] the position of
the driving flats on the pin 7, for which an individual level of
inaccuracy of 0.1 mm is set, for example, [0118] the position of
the driving flats on the shutter 5, for which an individual level
of inaccuracy of 0.04 mm is set, for example, and [0119] the
position of the sealing plane P' of the shutter 5, for which an
individual level of inaccuracy of 0.04 mm is set, for example.
[0120] Two dimensions are to be taken into account for the distance
Dc, i.e. two individual levels of inaccuracy to be defined: [0121]
the position of the sealing plane P of the body 2, for which an
individual level of inaccuracy of 0.1 mm is set, for example, and
[0122] the coaxial relationship of the bearings, for which a level
of inaccuracy of 0.04 mm in respect of the diameter of the bearings
is set, for example.
[0123] There is therefore a variation of .+-.0.1 mm in Dv and
.+-.0.07 mm in Dc.
[0124] In the extreme case (i), the compensation of play available
in the upward direction must be at least (+0.07)-(-0.1)=0.17 mm in
the example considered.
[0125] In the extreme case (ii), the compensation of play available
in the downward direction must be at least (-0.07)-(+0.1)=-0.17
mm.
[0126] There is therefore obtained a predefined overall error
margin of 0.34 mm, which means that the bearings are sized so that
each of them offers at least 0.34/2 mm, i.e. 0.17 mm, of radial
play in this example.
[0127] FIGS. 19 to 21 are similar to FIGS. 16 to 18 but correspond
to a valve 1 in which Dv<Dc, i.e. the sealing plane P' of the
shutter 5 is nearer the pin 7 than the sealing plane P of the body
2. As represented in FIG. 22, which represents the valve 1 in
accordance with the second embodiment of the invention in plan view
with the difference between the length l1 of the plate 30 and the
length l2 of the plate 31 exaggerated; by virtue of the different
lengths l1 and l2, in the closed position there are two leakage
sections S on respective opposite sides of the plate 31.
[0128] Although the second embodiment of the invention described
with references to FIGS. 12 to 21 relates to so-called "two-port"
valves, the second embodiment of the invention also covers
so-called "three-port" valves, as can be seen in FIG. 22.
[0129] The invention is not limited to the embodiments that have
just been described.
[0130] Unless otherwise specified, the expression "including a"
must be understood as synonymous with the expression "including at
least one".
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