Apparatus for governing the idling RPM of an internal combustion engine

An apparatus for governing an idling rpm of an internal combustion engine by controlling a quantity of operating fluid that can be supplied to the engine from an operating fluid source via at least two flow lines. A first valve opening cross section at a first valve opening is controlled by a first valve closing member, and a second valve opening cross section and a second valve opening is controlled by a second valve closing member. The first and second valve closing members are adjustable by an adjusting drive in such a manner that the first valve opening and the second valve opening are disposed parallel to one another between the operating medium source and the intake conduit of the engine. The valve closing members are coupled in such a way that upon their actuation, the first valve closing member always uncovers a flow cross section at the first valve opening first, and only then does the second valve closing member uncover a flow cross section at the second valve opening.

BACKGROUND OF THE INVENTION 
The invention is based on an apparatus for governing the idling rpm of an 
internal combustion engine. Such an apparatus is already known 
(Development of air-assisted injector system, SAE (Society of Automotive 
Engineers), Technical Paper Series 920294, pp. 57/58, 1992), in which a 
first valve closing member controls a first valve opening cross section to 
a first flow line, and a second valve closing member controls a second 
valve opening cross section to a second flow line. This first flow line 
communicates with a fuel metering device of the engine and serves to 
supply an operating medium, in particular aspirated air, to the fuel 
metering device for the sake of air-assisted fuel injection. The second 
flow line communicates directly with an intake conduit of the engine 
downstream of a throttle valve disposed in the intake conduit. Via the 
second flow line, operating medium can be supplied to the intake conduit 
and from there likewise to the engine. The first and second valve closing 
members are adjustable by means of an electric motor adjusting device via 
an adjusting member in the valve opening direction, counter to the force 
of a valve closing spring; when the adjusting drive is not activated, the 
valve closing members are held by the valve closing spring in a valve 
closing position. The known apparatus has the disadvantage that because of 
the rotationally symmetrical embodiment of the valve openings and of the 
valve closing members cooperating with them, upon axial adjustment of the 
valve closing member in traversing an extremely short stroke path, 
practically the entire opening cross section is uncovered, so that 
purposeful uncovering of only a defined partial cross section can be 
accomplished technically only with great difficulty, especially if, as in 
the prior art discussed, two valve closing members are actuated by means 
of a single rodlike final control element. Moreover, a large amount of 
space is required along with major effort and expense for production and 
installation. 
ADVANTAGES OF THE INVENTION 
The apparatus according to the invention for governing the idling rpm of an 
internal combustion engine has the advantage over the prior art that a 
valve opening can be opened continuously, and until the attainment of a 
predetermined free flow cross section, with the aid of a valve slide that 
uncovers the associated valve opening beginning at a point on its 
peripheral region. This purposeful uncovering of a defined flow cross 
section can be accomplished without extreme demands for accuracy of the 
electric motor adjusting drive, since the valve slide, in the course of a 
linear motion, for instance, relative to the associated valve opening 
uncovers an increasingly larger area thereof, so that until the opening is 
fully opened a certain amount of throttle action is preserved. 
In a feature of the invention, the possibility advantageously exists of 
adapting the shape of the opening and/or of the slide to the 
characteristic of the adjusting drive in such a way that a desired 
characteristic course of the uncovering of the flow cross section is 
attainable as a function of the actuation of the adjusting drive. In the 
apparatus of the invention the advantage is also attained that it is 
simple to manufacture and to install and also requires little space. 
By means of the provisions recited, advantageous further features of and 
improvements to the apparatus of the invention are possible.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
Before various exemplary embodiments of the invention are described in 
detail below, a preferred fundamental principle of an apparatus for 
governing the idling rpm of an internal combustion engine with 
air-assisted fuel injection be discussed in detail, in conjunction with 
the schematic illustration of FIG. 1. 
In detail, FIG. 1, shows a valve assembly 14 with a first valve 18, which 
can be considered the main valve, and a second valve 16, which acts as a 
secondary valve a or air enveloping valve. Throughout the disclosure and 
drawings, reference character 14 refers to a valve assembly. The two 
valves 16, 18 are in principle disposed parallel to one another, but a 
fuel metering device 22, in particular a set of injection nozzles, is 
located in series with the valve 16. The fuel metering device 22 is 
supplied with fuel, for example from a controlled fuel pump (not shown), 
via a fuel line 24 in a known manner, not to be described in further 
detail here. The quantity of operating medium supplied to the fuel 
metering device 22 from the outlet side of the valve 16 via a first flow 
line 20a, that is, aspirated or combustion air or a mixture of fresh air 
and recirculated exhaust gases, serves the purpose of so-called "air 
envelopment" for the injection nozzle or nozzles of the fuel metering 
device 22; the throttling action of the injection nozzle or nozzles in 
FIG. 1 is suggested by a throttle restriction 22a of the fuel metering 
device. The fuel mixture produced along with the enveloping air in the 
fuel metering device 22 is finally supplied to the engine 12, as 
schematically suggested in FIG. 1 by a mixture inlet line 21, for instance 
into the individual intake tubes of the cylinders directly upstream of the 
inlet valves. The outlet side of the other valve 18, conversely, 
communicates with a second flow line 20b directly with an intake line 23 
of the engine 12, so as to supply idling air to the engine in a controlled 
way. A parallel path, into which a throttle valve 28 is inserted in the 
conventional way, is also provided, parallel to the above-described valve 
assembly 14, between the operating medium source 10 and the engine 12 or 
its intake line 23. If as suggested in FIG. 1 the throttle valve 28 
assumes its closing position or is nearly closed, the operating medium or 
combustion air is supplied to the engine 12 via the valve assembly as 
follows: Upon actuation of the valve assembly with the aid of an 
associated, for instance electromechanical adjusting drive 29, the first 
valve 16 opens first, so that the fuel metering device 22 is supplied with 
enveloping air that assures effective mixture preparation in terms of the 
fuel supplied to the fuel metering device 22 via the fuel line 24. Not 
until the valve 16 is sufficiently opened, so as to supply the desired 
quantity of operating medium or combustion air to the fuel metering device 
22, does the second valve 18 open, so as to supply the engine 12 in the 
usual way with the quantity of operating medium or combustion air that is 
required, in addition to the enveloping air supplied via the mixture inlet 
line 21, so that the idling rpm of the engine 12 can be maintained. Care 
must be taken that the throttling action of the elements of the fuel 
metering device 22, suggested by the throttle restriction 22a, be constant 
and greater than the throttling action of the second valve 18 in its fully 
opened state. 
As FIG. 2 shows, the valve assembly 14 described above in conjunction with 
FIG. 1 can be realized, in a first preferred exemplary embodiment of the 
invention, in the form of a rotary valve assembly or rotary adjuster. This 
rotary adjuster, as shown in FIG. 2, includes a housing 30 with an inlet 
32, a first outlet 34 and a second outlet 36. The housing 30 defines a 
cylindrical chamber 37, in which a rotatable component 38 is disposed, 
which can be driven for counterclockwise rotation by an associated 
electromechanical adjusting drive 29 (FIG. 1), as represented by an arrow. 
The rotatable component 38 carries two integrally formed-on or otherwise 
suitably firmly mounted valve closing members 38a and 38b, for instance in 
the form of tube segments, each embodied as curved valve slides, each with 
a curved sealing face on the circumference; the respective curved sealing 
faces are embodied as complementary to a respective sealing face 34a and 
36a on the valve housing 30 surrounding the associated valve opening of 
the outlet 34 and 36 and are adjustable in a slidably displaceable manner 
relative to the respective associated sealing face 34a and 36a in order to 
uncover a desired valve opening cross section. 
In the exemplary embodiment shown in FIG. 2, the valve closing members 38a 
and 38b may be considered to be parts of a cylindrical apron of the 
rotatable component 38, which between them in a circumferential direction 
define at least one recess 39 and in the axial direction, or in other 
words perpendicular to the plane of the drawing in FIG. 2, extend over at 
least the full height of the valve openings at the first outlet 34 and the 
second outlet 36. The outer faces, in terms of the radial direction, of 
the valve closing members 38a and 38b are consequently cylindrical 
surfaces. In a corresponding way, the sealing faces 34a and 36a on the 
inner end of the two outlets 34, 36 are also cylindrical surfaces; the 
pairs of complementary cylindrical surfaces can coincide sufficiently far 
in terms of area so that when the two valves 16, 18 (FIG. 1) are intended 
to be closed, a leakage flow can be avoided or at least reduced to a 
minimum. This closing position for the two valves or the two outlets 34, 
36 is shown in FIG. 2. 0n the condition that the outlets 34 and 36 have a 
round opening cross section, which is advantageous and usual for 
engineering reasons, then beginning at the closing position shown in FIG. 
2, upon a rotary motion of the rotatable component 38, first the first 
outlet 34 is uncovered by a rear control edge 40 of the first valve 
closing member 38, specifically being uncovered beginning at a point on 
the peripheral region of its valve opening. Upon further rotation of the 
rotatable component 38 counterclockwise, an increasingly larger, initially 
circular-segmental cross-sectional area of the valve opening at the first 
outlet 34 is then uncovered, so that the fuel metering device 22 is 
supplied with an increasing, controlled quantity of enveloping air. In 
this phase of operation, the second outlet 36 initially still remains 
closed, since the second valve closing member 38b extends over a larger 
arc or angle of arc, so that the rear edge 41, in terms of the direction 
of rotation, of the second valve closing member 38b does not reach the 
edge of the valve opening of the second outlet 36 for instance until the 
opening of the first outlet 34 of the associated valve closing member 38a 
has already been uncovered in part or even completely. In this connection 
it should be noted that in the case of a rectangular valve opening with an 
edge extending parallel to the rear edge of the associated valve closing 
member, the uncovering of the valve opening takes place along a line or a 
narrow axial gap, and this is likewise intended to be covered by the 
wording "beginning at a point on its peripheral region", especially since 
the vertical projection of the opening line, for instance in FIG. 2, 
likewise results in a point. On the other hand, an immediate uncovering of 
a gaplike opening, should that be undesired, can be avoided by disposing 
and embodying the rear edge of the valve closing member and the applicable 
edge of the associated opening in such a way that they extend toward one 
another at a certain angle, so that the opening begins at a point of the 
peripheral region of the valve opening, and upon further rotation of the 
rotatable component 38 a triangular opening cross section is first 
uncovered. 
FIG. 3 of the drawing shows a version of a rotary valve assembly that is 
slightly modified compared with the exemplary embodiment of FIG. 2, for 
embodying the valve assembly 14 shown in FIG. 1. In the exemplary 
embodiment of FIG. 3, with otherwise a substantially identical layout to 
the rotary valve assembly of FIG. 2, the two outlets 34, 36 are disposed 
close together in the circumferential direction of the housing 30, and the 
two separate valve closing members 38a and 38b of FIG. 2 are combined into 
a single valve closing member 38c, which extends over a greater 
circumferential angle of the rotatable component 38. If this latter 
component, in the rotary valve assembly of FIG. 3, is rotated 
counterclockwise as indicated by an arrow, with the aid of the associated 
electromechanical adjusting drive, then by means of the common valve 
closing member 38c for the two outlets 34, 36, first the first outlet 34 
is opened completely by the rear control edge 40, and only after that, 
with a delay corresponding to the distance between the valve openings of 
the two outlets 34, 36, is the opening of the valve opening at the second 
outlet 36 initiated by the control edge 40. A particular advantage of the 
rotary valve assembly of FIG. 3 is that the immediately adjacent valve 
housing faces 34a and 36a can be machined jointly in a single operation, 
and that only a single valve closing member 38c needs to be provided, 
which becomes particularly important if this component is manufactured 
separately and joined to the rotatable component 38 for instance by means 
of a screw connection. 
FIG. 4 shows a further exemplary embodiment of a valve assembly according 
to the invention. In this valve assembly, embodied as a rotary adjuster, 
and in which as in the exemplary embodiment of FIG. 2 a housing 30 with an 
inlet 32, a first outlet 34 and a second outlet 36 is again provided, in 
which a rotatable component 38 having two valve closing members 38a and 
38b, which below for the sake of simplicity will be again combined into a 
unit 38c designed as a valve closing member, the first outlet 34 is 
however located behind the inlet 32 in terms of the direction of rotation 
of the rotatable component 38, or in other words counterclockwise. In the 
position of the rotatable component 38 shown in FIG. 4, the inlet 32 and 
the first outlet 34 are closed. If the rotatable component 38 is now 
rotated counterclockwise, then the first outlet 34 is first opened 
increasingly farther, by the valve closing member 38c extending over a 
relatively wide arc angle, for instance of more than 90.degree. , to a 
recess 38d provided in the outer jacket face of the valve closing member 
38c, so that combustion air can flow from the inlet 32 via the recess 38d, 
acting as a connecting conduit, as far as the rear control edge 40 on the 
valve closing member 38a and then can flow only to the first outlet 34. 
The inlet 32 opposite the cylindrical chamber 37 in the interior of the 
housing 30 initially remains closed. Not until the first outlet 34 is 
opened to the extent specified by the structural design of the housing 30 
on the one hand and by the valve closing member 38c on the other does the 
rear edge 41, in terms of the direction of rotation of the valve closing 
member 38c enter the region of the valve opening of the inlet 32, so that 
this inlet is opened increasingly farther toward the chamber 37, and 
allows combustion air to flow to the second outlet 36 via the chamber 37 
provided in the housing 30. Accordingly, once again, initially a flow 
cross section for the first outlet 34 is uncovered, and then with a 
specified delay a parallel flow cross section is uncovered for supplying 
combustion air for idling governing from the inlet 32 to the second outlet 
36. The rotatable valve closing member 38c, embodied as a valve slide and 
replacing or combining the two separate valve closing members 38a and 38b, 
in its closing position shown in FIG. 4, assures a practically 
leakage-free closure of the valve assembly partially because of the 
sealing face 34a. The inlet 32 and the first outlet 34 may be embodied 
directly next to one another, in terms of the circumferential direction of 
the housing 30. 
In FIGS. 5a and 5b of the drawing, a further rotary valve assembly 
according to the invention for embodying the valve assembly 14 of FIG. 1 
is shown. This further modified rotary valve assembly is similar to that 
of FIG. 3 in the respect that once again only a single valve closing 
member 38c in the form of a tubular segment is provided; however, it 
differs from the exemplary embodiment described previously in that the two 
outlets 34, 36, offset in the circumferential direction, are also offset 
relative to one another in height, or in other words axially in the 
direction of the axis of rotation of the rotatable component 38, as is 
shown particularly clearly in FIG. 5b. As a result, partial overlapping of 
the two outlets 34, 36 in the circumferential direction is made possible, 
thus lending greater freedom in terms of the onset of supply of idling air 
to the engine 12, once the first outlet 34 for the enveloping air has 
first been opened more or less completely. In the exemplary embodiment in 
question, the point of the valve opening of the first outlet 34 that is 
located farthest to the rear in the circumferential direction and is 
opened last by the rear edge 41 of the valve closing member 38c in the 
course of a rotation thereof in the clockwise direction, is located in the 
axial direction substantially on a line with the forward edge of the valve 
opening of the second outlet 36. The uncovering of the valve opening at 
the second outlet 36 accordingly begins directly upon or after the 
complete uncovering of the valve opening at the first outlet 34 by the 
rear edge 41. From an engineering standpoint, the rotary valve assembly of 
FIGS. 5a and 5b offers similar advantages to the rotary valve assemblies 
of FIGS. 2-4 described above. 
A further variant of a rotary valve assembly with the option of overlapping 
uncovering of the outlets 34 and 36 is shown in FIGS. 6a and 6b. In this 
further modified rotary valve assembly, the second outlet 36 is again 
provided in the wall of the housing 30 extending in the circumferential 
direction and is closeable and uncoverable with the aid of a valve closing 
member 38b, in the form of a tubular segment, on the rotatable component 
38, similarly to the situation in the exemplary embodiment of FIG. 2. In 
the exemplary embodiment of FIGS. 6a and 6b, however, the first outlet 34 
is provided on an end face 30a of the housing 30 and is closeable and 
uncoverable by means of a sector-shaped valve closing member 38a disposed 
at right angles to the axis of rotation of the rotatable component 38; the 
valve closing member 38a adjoins the upper, or righthand end in terms of 
FIG. 6 of the circumferentially extending valve closing member 38b, and 
extends beginning at the circumference thereof in sector shape radially 
inward toward the axis of rotation of the rotatable component 38. 
One advantage of the valve construction of FIG. 6a and 6b over the 
exemplary embodiment of FIGS. 5a and 5b is that overall, a lower 
structural height can be attained. 
While various rotary valve assemblies or rotary adjusters have been 
described above for embodying the valve assembly 14 of FIG. 1, such a 
valve assembly 14, with two valves connected in principle parallel, can 
also be achieved in a further feature of the invention with the aid of a 
reciprocating or piston adjuster with axially adjustable valve closing 
members. 
One such reciprocating adjuster is shown in FIG. 7. The valve assembly 
embodied as a reciprocating adjuster shown in FIG. 7 again has a housing 
30, which defines a cylindrical chamber 37, which is provided with a 
radial inlet 32, an axial first outlet 34, and a radial second outlet 36. 
In the valve assembly of FIG. 7, the movable element 38 connected to the 
adjusting drive (not shown) replaces the rotatable component 38 of the 
exemplary embodiments discussed above and is an element that is adjustable 
in the axial direction, as indicated by an arrow, for opening the outlets 
34, 36 and that has two valve closing members 38a and 38b for cooperation 
with the valve openings on the first outlet 34 and on the second outlet 
36, respectively. 
In detail, the valve closing member 38a is a cylindrical element of the 
side of the movable component 38 remote from the adjusting drive, and on 
its free end it has a conical valve face for cooperation with a conical 
seat 34a at the valve opening of the first outlet 34. Because of this 
design, the cross section of the first outlet 34, as in conventional 
valves with an axially adjustable valve body, is already uncovered upon a 
slight stroke of the axially adjustable component 38, which is not of 
critical importance in the sense that the fuel metering device 22, which 
as noted at the outset has its own throttle restriction 22a is connected 
to the first outlet 34. The second valve closing member 38b may be 
considered to be a wall region of a cylindrical apron of the movable 
component 38, and when the second outlet 36 is closed, it rests sealingly 
against the cylindrical inner wall surface 36a of the chamber 37 defined 
by the housing 30. 
Once the first outlet 34, in the initial phase of an axial motion of the 
movable component 38, has been substantially completely uncovered by its 
associated valve closing member 38, a further axial motion of the movable 
component 38, brought about by the adjusting drive, causes the second 
outlet 36 to be opened increasingly farther by the rear edge 41 in a 
defined way--in FIG. 7, from top to bottom--by axial shifting of its 
slidelike valve closing member 38b. In this case as well, as explained in 
conjunction with the exemplary embodiment of FIG. 2, it is possible by 
suitable design of the peripheral curve of the valve opening at the second 
outlet 36 on the one hand and of the shape of the valve closing member 38b 
on the other once again to specify the desired linkage between the axial 
position of the movable component 38 and the uncovered cross section for 
the second outlet 36, depending on the particular requirements. 
FIG. 8 of the drawing, as a further exemplary embodiment, shows a valve 
assembly according to the invention embodied as a reciprocating or piston 
adjuster; it can be considered a variant of the piston adjuster of FIG. 7. 
In detail, the valve assembly of FIG. 8 has a housing 30 with a radially 
disposed inlet 32 and a first outlet 34 diametrically opposite it, which 
however, is offset in height or in the axial direction from the inlet 
32--upward, in terms of FIG. 8. The second outlet 36 in the exemplary 
embodiment in question is disposed as an axial outlet above the radial 
first outlet 34. 
In the interior 37 of the housing 30, an axially adjustable, pistonlike 
component 38 is again provided, which beginning at the closing position 
shown in FIG. 8 can be moved axially downward, as indicated by an arrow, 
with the aid of the associated electromechanical adjusting drive (not 
shown), so as to open the outlets 34 and 36 in succession, in that order. 
In the exemplary embodiment in question, the adjustable component 38 again 
has two valve closing members 38a, 38b, which can be considered to be 
parts of a piston apron or as part of a cylinder, and of which the valve 
closing member 38b is disposed at the inlet 32 while the valve closing 
member 38a is disposed at the first outlet 34. Unlike the exemplary 
embodiment of FIG. 7, the valve closing members 38a, 38b in the exemplary 
embodiment of FIG. 8 are recessed radially inward relative to the 
platelike base 38e of the adjustable component 38, and as a result 
together with the inner wall of the housing 30 they define an annular 
conduit 43. The valve closing member 38a is also provided with a step or 
radial recess 38f at the first outlet 34. The annular conduit 43 could 
also be formed by a groove in the inner wall of the housing 30 as shown in 
FIG. 8a. The conduit 43 may also be a hollow chamber that communicates 
with the inlet 32 through a connecting conduit, not shown. 
In the design, described, a downward motion of the adjustable component 38, 
in the direction of the arrow shown, causes the recess 38f to be opened to 
the annular conduit 43, thus initially making a connection between the 
inlet 32 and the first outlet 34, while the second outlet 36 initially 
still remains closed. Not until a predetermined opening cross section for 
the first outlet 34 has been uncovered does the upper edge of the valve 
closing member 38b enter the region of the valve opening at the inlet 32, 
so that combustion air can now flow from the inlet 32 into the interior 37 
of the housing 30 and from there reaches the second outlet 36. In the 
exemplary embodiment of FIG. 8 as well, the practically leakage-free 
closure at the inlet 32 sought in accordance with the invention and the 
chronologically staggered opening of the outlets 34 and 36 are again 
attained. 
Another advantageous exemplary embodiment of a valve assembly according to 
the invention is shown in FIGS. 9a-9c. In this valve assembly, the inlet 
32 and the second outlet 36 are embodied as radial inlet and outlet 
devices located at the same height, while the first outlet 34 is provided 
at a second, lower level in the exemplary embodiment, in the form of an 
elongated outlet in the wall of a cylindrical housing 30. In the interior 
37 of the housing, a rotatable component 38 is once again provided--that 
is, the valve assembly of FIGS. 9a-9c is again embodied as a rotary 
adjuster which which has a single valve closing member 38c of 
circular--sectorlike cross section, which performs the function of the 
separate valve closing members 38a, 38b of the exemplary embodiments of 
the previous drawing figures. 
In the closing position shown in FIG. 9b of the valve assembly in question, 
the valve closing member 38c closes the first outlet 34 with an oblique 
sealing face 38g, which rests on an oblique sealing face 38d complementary 
to it of the housing, and it closes the second outlet 36 with a curved 
sealing face 38a extending in the circumferential direction. Upon 
counterclockwise rotation of the rotatable component 38, the oblique 
sealing face 38g first lifts perpendicularly to a certain extent from the 
oblique sealing face 30d provided on the housing 30, and as a result the 
first outlet 34 is uncovered to the interior 37, while the second outlet 
36 continues to be closed by the circumferentially extending sealing face 
38h, which extends over a correspondingly larger arc. Not until the first 
outlet 34 is uncovered to the desired cross section does opening of the 
valve opening at the second outlet 36 to the interior 37 begin, upon 
further rotation of the sectorlike valve closing member 38c. 
The valve assembly of FIGS. 9a-9c is especially advantageous in the sense 
that the opening for the first outlet 34 is effected, similarly to the 
situation with a reciprocating adjuster, by means of a particular movement 
apart of the sealing faces 38g, 30d, so that by slightly rotating the 
component 38 with the aid of the associated adjusting drive, a practically 
complete opening of the first outlet 34 can be rapidly achieved. On the 
other hand, an excellent sealing action can be attained for both outlets 
34, 36, because when the oblique sealing face 38g provided on the valve 
closing member 38c slides in wedgelike fashion onto the oblique sealing 
face 30d of the housing 30, a superficial contact between the parts that 
are movable relative to one another is again attained, as with the sealing 
face 38h extending circumferentially. 
In summary, from the above description it becomes clear that a valve 
assembly on the basic principle described in conjunction with FIG. 1, 
namely with valves disposed parallel to one another and uncoverable in 
succession can be achieved to meet given requirements structurally in the 
most various ways by means of suitably embodied reciprocating adjusters or 
rotary adjusters, which can be manufactured economically with a 
comparatively simple design and high function reliability. 
The foregoing relates to preferred exemplary embodiments of the invention, 
it being understood that other variants and embodiments thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.