Information
-
Patent Grant
-
6681732
-
Patent Number
6,681,732
-
Date Filed
Friday, October 5, 200123 years ago
-
Date Issued
Tuesday, January 27, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Denion; Thomas
- Riddle; Kyle
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 9011
- 251 3001
- 251 12903
- 251 12907
- 251 12909
- 251 12915
-
International Classifications
-
Abstract
A control device for switching an intake or exhaust valve of an internal combustion engine has a control valve with a control valve piston for controlling flow of a hydraulic medium from a pressure line to the intake or exhaust valve. At least one actuating element is correlated with the intake or exhaust valve and has a first end acted on by the hydraulic medium. At least one damping device interacts with the at least one actuating element and is arranged at a second end of the actuating element opposite the first end. The at least one damping device exerts a damping force onto the actuating element counteracting a force exerted by the hydraulic medium.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a control device for switching intake and exhaust valves of internal combustion engines, wherein the control device comprises a control valve with a control valve piston by which the supply of hydraulic medium from a pressure line to the intake or exhaust valve can be controlled.
2. Description of the Related Art
Camshafts are conventionally used for switching or controlling intake or exhaust valves of internal combustion engines. It is also known to hydraulically control the intake or exhaust valves. The hydraulic medium which is supplied by a pressure line is supplied via the control valve piston to the intake or exhaust valves which are then moved into the required position by the pressurized hydraulic medium.
SUMMARY OF THE INVENTION
It is an object of the present invention to configure the control device of the aforementioned kind such that the intake or exhaust valves can be adjusted optimally.
In accordance with the present invention, this is achieved in that the intake or exhaust valve has at least one actuating element which has at least one damping device at its side facing away from the hydraulic medium wherein the damping device counteracts the force exerted by the hydraulic medium onto the actuating element.
In the control device according to the present invention the hydraulic damping can be adjusted such that it conforms to the activation curve of the cam of a camshaft. In this way, it is possible to provide harmonic transitions, as they are known from camshafts, even for camshaft-free internal combustion engines in a simple way and with significant advantages in comparison to conventionally controlled engines.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
FIG. 1
is an axial section of a part of a first embodiment of the control device according to the invention;
FIG. 2
is an axial section of a part of an internal combustion engine showing an intake valve and an exhaust valve;
FIG. 3
shows the control device according to
FIG. 1
in axial section;
FIG. 4
is a second embodiment of the control device according to the invention;
FIG. 5
shows on an enlarged scale and in axial section a control valve of the control device of
FIG. 3
according to the invention in a first end position of the control valve piston;
FIG. 6
shows on an enlarged scale and in axial section a control valve of the control device according to the invention of
FIG. 3
in a second end position of the control valve piston;
FIG. 7
is an axial section of a third embodiment of the control device according to the invention;
FIG. 8
shows in an axial section and in a schematic illustration a control valve in a position in which the work connector is connected with the tank connector;
FIG. 9
shows the control valve according to
FIG. 8
in a position in which the pressure connector is connected to the work connector;
FIG. 10
shows the damping action of the control valve piston of the control device according to the invention;
FIG. 11
shows an axial cross-section of a fourth embodiment of the control device according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The control device according to the invention is provided for switching or controlling intake valves and exhaust valves of internal combustion engines—preferably diesel engines—which have no camshaft. The control device has a control valve
1
which is provided with a control valve piston
2
. In
FIG. 1
, the control valve piston
2
is shown in a first end position in the upper half of the drawing and in a second end position in the lower half of the drawing. The control valve piston
2
is axially slidably arranged in the bushing
3
which is pressed into a receptacle
4
of the valve housing
5
. Both ends of the valve housing
5
are closed off by stops
6
and
7
against which the control valve piston
2
rests in the first and second end positions. The control valve piston
2
forms an armature which is moved in the desired direction by supplying current to or exciting the two coils
8
and
9
. The two coils
8
,
9
which are connected to a computer unit (not illustrated) are provided in the area of the stops
6
and
7
, respectively. The two coils
8
,
9
can be connected by welding to the valve housing
5
in the area where the ends of the control valve piston
2
are located (in the vicinity of the stops
6
,
7
) and have curlers
8
a,
9
a
for this purpose.
The bushing
3
of the control valve
1
can also be eliminated so that a constructively simplified configuration results.
The bushing
3
has two tank connectors T as well as two work connectors A via which a hydraulic medium can be supplied from a pressure line
10
(pressure connector P). The pressure line
10
is a bore in a housing
11
which is preferably a monolithic part of the valve housing
5
. The axis of the pressure line
10
is positioned perpendicularly to the piston axis of the piston
2
.
The control valve piston
2
is provided with three annular grooves
12
-
14
positioned at an axial spacing to one another. Depending on the position of the control valve piston
2
, the hydraulic medium can flow, coming from the pressure line
10
, to the tank connector (relief bore) T or to the work connector A. On the side of the control valve
1
facing away from the pressure line
10
an annular pressure chamber
15
is provided into which bores
16
open which connect the work connectors A with the pressure chamber
15
.
By means of the pressurized hydraulic medium which flows through the annular pressure chamber
15
, a bucket tappet
17
is moved against a counter force, preferably against the force of at least one coil pressure spring
18
. The bucket tappet
17
has a central, axially extending projection
19
with which it engages the depression or recess
20
of the housing
11
under the force of the coil pressure spring
18
. As is illustrated in
FIG. 2
, the bucket tappet
17
is provided with a valve shaft
21
which carries at its free end a valve disc
22
with which an intake/exhaust opening
23
opening into the combustion chamber
24
can be closed off. In the combustion chamber
24
the piston (not illustrated) of the internal combustion engine is arranged. The internal combustion engine has several such combustion chambers
24
with corresponding intake valves and exhaust valves. In
FIG. 2
two such valves are illustrated in an exemplary fashion; they provide two intake/exhaust openings
23
that open or close as a function of the number of revolutions (revolutions per minute—rpm) of the crankshaft (not illustrated) of the engine. In a closed position, the valve disc
22
rests in a seal-tight way on the valve seat
25
under the force of the coil pressure spring
18
.
In order to open the corresponding valve, the hydraulic medium, controlled by the computer unit, is supplied via the pressure line
10
. The coil
9
is supplied with current (excited)—this being controlled also by the computer unit—so that the control valve piston
2
is moved into the end position illustrated in
FIG. 1
in the upper half in which the control valve piston
2
rests against the stop
7
. The hydraulic medium therefore can flow from the pressure line
10
via the work connectors A and the bores
16
into the annular pressure chamber
15
. The hydraulic pressure is greater than the counter force exerted by the coil pressure spring
18
so that the bucket tappet
17
can be moved against this spring force and the opening
23
into the combustion chamber
24
is opened. Fuel can then be injected in the way known in the art into the combustion chamber
24
. This injection process is also computer-controlled, as is known in the art. As soon as the injection step is complete, the other coil
8
is supplied with current (excited)—this being controlled also by the computer unit—so that the control valve piston
2
can be moved into the end position illustrated in the lower half of FIG.
1
. In this position, the pressure line
10
is connected with the tank line (relief bore) T. Accordingly, the bucket tappet
17
is no longer loaded by the hydraulic medium but by the spring
18
and is returned into the initial position illustrated in
FIG. 1
in which the valve disc
22
closes the opening
23
.
In the described embodiment the triggering behavior of the intake/exhaust valves is controlled such that the hydraulic medium actuates through the control valve piston
2
of the control valve the bucket tappet
17
which, in turn, actuates the intake or exhaust valve and thus makes possible the gas exchange in the combustion chambers
24
. The control valves
1
can be controlled in a variable way so that a high power utilization, i.e., an increased efficiency, can be obtained. Moreover, the exhaust emissions are considerably improved, in particular, the NO
x
output is reduced. This is based on the fact that the fuel/air ratio of the combustion mixture is adjusted optimally to the corresponding rpm (revolutions per minute) and load moment of the engine.
As a result of the hydraulic adjustment of the bucket tappet
17
acting as a hydraulic piston, a hydraulic damping of the bucket tappet
17
is possible which then corresponds to the activation curve of a cam. This enables the realization of harmonic transitions—as they are known from the camshafts—also for hydraulic control of the intake/exhaust valves without camshafts. As a result of the high damping, the motor noise is considerably reduced. The damping of the bucket tappet
17
is achieved (
FIG. 10
) in that the wall
26
a
of the receptacle
26
receiving the bucket tappet
17
has at least one opening
27
through which a damping medium, preferably lubricant oil, can be supplied.
In the left half of
FIG. 10
, the bucket tappet
17
is illustrated in its one end position into which it has been moved by the hydraulic medium coming from the annular pressure chamber
15
(
FIG. 1
) for opening the intake/exhaust valve. In this way, the damping medium present within the bucket tappet
17
is displaced through the opening
27
so that the movement of the bucket tappet
17
is dampened. In the right half of
FIG. 10
, the bucket tappet
17
is illustrated in its other end position into which it is moved by the spring
18
and in which its projection
19
rests against the bottom of the recess
20
(FIG.
1
). In this end position, the bucket tappet
17
has been moved back so far that the opening
27
is unobstructed so that the damping medium can again reach the area underneath the bucket tappet
17
(FIG.
10
).
The bucket tappet
17
can also be loaded by a hydraulic counter spring. In this case, the bucket tappet
17
is arranged between two hydraulic chambers. With this configuration, the system can be returned by means of an additional valve or an oil spring storage device.
The control valve
1
is arranged in a housing part
28
(
FIG. 3
) of the control device. The housing part
28
is mounted on an engine block
29
in which the different intake/exhaust valves with the corresponding bucket tappets
17
, are arranged. The axis of the bucket tappet
17
is aligned with the axis of the valve shaft
21
. The axis of the annular chamber
15
, via which the hydraulic medium is supplied, is also aligned with the axis of the bucket tappet
17
. The control valve
1
is positioned above the pressure chamber
15
.
FIG. 4
shows an embodiment in which the control valve
1
is arranged in the area adjacent to the intake/exhaust valve and which comprises a transmission unit
32
,
33
for transmitting the movement of the control valve piston onto the intake/exhaust valve. The control valve
1
is configured identically to the embodiment according to
FIGS. 1 through 3
. Depending on the position of the control valve piston
2
, the hydraulic medium supplied via the pressure line
10
reaches the tank connector T or the work connector A. The pressurized hydraulic medium within the pressure line
10
supplied to the pressure chamber
15
reaches via lines (not illustrated) the work connector A. From here the hydraulic medium reaches via a bore
30
in the engine block
29
the cylinder chamber
31
in which a transmission piston
32
is moveably arranged. The piston
32
is moved upwardly (
FIG. 4
) by the hydraulic medium. The end of the piston rod of the piston
32
which projects upwardly past the cylinder chamber
31
is connected by a ball and socket joint to one arm of a transmission element
33
in the form of a two-arm elbow lever
33
, and the elbow lever
33
is thus pivoted by the upwardly moving piston
32
in the clockwise direction. The elbow lever
33
is supported on a cam-shaped adjusting device
39
. By means of the elbow lever
33
the valve shaft
21
is moved downwardly against the force of the coil pressure spring
18
so that the valve disc
22
is lifted off the seat and the intake opening
23
is opened. The valve shaft
21
is moveably arranged in a slide bushing
34
which is mounted in a bore
35
of the engine block
29
. On the upper end of the valve shaft
21
a spring plate
36
is arranged on which the coil pressure spring
18
is supported with one end. The other end of the spring
18
rests against the bottom
37
of a depression or recess
38
of a transverse wall
40
of the engine block
29
. The transverse wall
40
delimits a receptacle
41
in which the elbow lever
33
is arranged and in which the valve shaft
21
with the spring plate
36
as well as the piston rod carrying the piston
32
are positioned. The piston
32
and the cylinder chamber
31
are arranged in a cylinder
42
which is arranged in a receptacle
43
in the transverse wall
40
of the engine block
29
.
With the cam-shaped adjusting device
39
, a sensitive adjustment of the position of the intake/exhaust valve is possible. It is advantageously possible to control this cam-shaped adjusting device
39
in a targeted way during operation in order to achieve a stroke change of the intake/exhaust valve
21
,
22
in this way.
By means of the adjusting device
39
, preferably in the form of a camshaft, overlaid control actions or governing actions of the engine can be performed. In an advantageous way, a delayed or advanced opening or closing of the intake and exhaust valves is possible.
In the position of the control valve piston
2
according to
FIG. 5
, the pressure medium is introduced via the pressure line
10
into the annular groove
13
which is closed relative to the pressure chamber
15
. The annular groove
12
is relieved to the tank T so that the hydraulic medium can flow from the pressure chamber
15
in the direction of the illustrated arrows via the bores
16
back to the tank. In this position the control valve piston
2
rests against the stop
6
. The control valve piston
2
in this end position is secured by residual magnetism so that current supply to (excitation of) the coil
8
is not required in this switching position.
FIG. 6
shows the control valve piston
2
in the other switching position in which it rests against the stop
7
. In this position the control valve piston
2
is also secured by residual magnetism so that the coil
9
must not be supplied with current in order to secure the control valve piston
2
in this position. The pressurized hydraulic medium is conveyed from the pressure line
10
via the annular grooves
12
,
13
and the bores
16
into the pressure chamber
15
. The hydraulic medium thus moves the bucket tappet
17
(
FIG. 1
) in the described way.
In the embodiment according to
FIG. 7
, the bucket tappet
17
is arranged in the area below and adjacent to the valve shaft
21
with the valve disc
22
. The bucket tappet
17
is connected to an axle
44
which projects with play through a through opening
45
and has one arm of a transmisison element
33
in the form of an elbow lever
33
supported on its free end by means of a ball and socket joint. The other arm of the elbow lever
33
is positioned according to the embodiment of
FIG. 4
at the upper end of the valve shaft
21
which at the upper end is provided with a spring plate
36
on which the coil pressure spring
18
is supported. By means of the coil pressure spring
18
the valve plate
22
is pulled into its closed position. The control device according to
FIG. 7
operates in other respects in the same way as the embodiment according to FIG.
4
.
FIGS. 8 and 9
show a control valve
1
with a control valve piston
2
which delimits one side of a pressure chamber
46
into which a bore
47
opens which is closed by a valve element
48
, such as a valve ball. The pressure chamber
46
is delimited by a housing wall
49
in which the bore
47
is provided. The valve element
48
is secured by the armature element or base plate
50
in a closed position, as illustrated in FIG.
8
. The armature base plate
50
is subjected to the force of at least one pressure spring
51
which is arranged in a receptacle
52
of the valve housing
5
. The receptacle
52
is delimited at one side by the housing wall
49
. Advantageously, the receptacle
52
is delimited by a removable hood-shaped lid
53
which is fastened with its edge on the housing wall
49
. In the lid
53
a coil
54
is arranged which, when excited, pulls the armature base plate
50
against the force of the pressure spring
51
toward it. The lid
53
is provided with at least one bore
71
opening into the receptacle chamber
52
via which a pressure-less outflow of the control oil present in the receptacle
52
is possible.
The control valve piston
2
is provided with a supply line in the form of a bore
55
which connects the pressure line
10
with the pressure chamber
46
when the valve, comprised of the bore
47
and the valve element
4
, is closed. The cross-section of the bore
55
is smaller than the cross-section of the bore
47
which is closed by the valve element
48
.
The control valve piston
2
is provided with an annular chamber
56
in its mantle surface which is connected with the pressure chamber
15
in any position of the control valve piston
2
. The pressure chamber
56
is delimited at the end facing away from the pressure chamber
46
by a collar
57
with which the control valve piston
2
rests against the inner wall
58
of the receptacle
4
of the valve housing
5
. The annular chamber
46
is delimited at the axial other end by a collar
59
which has a smaller outer diameter than the receptacle
4
. The cylindrical mantle surface
60
of the collar
59
has a transition by means of a conical surface
61
into a cylindrical mantle surface
62
with which the control valve piston
2
rests against the inner wall
63
of an area of the receptacle
4
having a greater diameter.
At the end face facing the bore
47
the control valve piston
2
is provided with a central projection
64
in which a throttle
65
is provided which is formed by a radial depression. When the valve is open (FIG.
9
), the throttle
65
connects the bore
47
with the pressure chamber
46
.
When the valve is closed, the annular chamber
56
of the control valve piston
2
is relieved in the direction toward the tank so that the hydraulic medium can return from the pressure chamber
15
via the annular chamber
56
to the tank. The receptacle
52
arranged between the armature base plate
50
and the housing wall
49
is also relieved to the tank.
When the internal combustion engine is to be provided with a fuel/air mixture charge, the coil
54
is supplied with current. The anchor base plate
50
is pulled toward the coil
54
against the force of the pressure spring
51
. The valve element
48
is moved by the force of the hydraulic medium present within the pressure chamber
46
into the open position (
FIG. 9
) so that the hydraulic medium can flow out of the pressure chamber
46
via the bore
47
into the receptacle
52
which is closed relative to the tank in the position according to FIG.
9
. The control valve piston
2
is moved to the right as a result of the surface area ratios loaded by the hydraulic medium until it rests against the housing wall
49
. This has the result that first the annular chamber
56
is closed relative to the tank. Subsequently, the connection between the pressure line
10
and the pressure chamber
15
is opened by the conical surface
61
of the control valve piston
2
so that the pressurized hydraulic medium then can flow in the manner described in the preceding embodiments to the pressure chamber
15
in order to thus move the bucket tappet
17
in the way described above and to thereby open the intake/exhaust valve
21
,
22
.
The bore
47
in the housing wall
49
has a greater flow cross-section than the bore
55
in the control valve piston
2
. This ensures that the hydraulic medium in the pressure chamber
46
in front of the control valve piston
2
can flow out faster via the bore
47
than the hydraulic medium can flow into the pressure chamber
46
via the pressure line
10
and the bore
55
. Accordingly, the pressure in the pressure chamber
46
in front of the control valve piston
2
will drop toward zero so that the control valve piston
2
can be moved into the release position according to
FIG. 9
as a result of the surface area differences.
The control valve piston
2
is positioned with its cylindrical mantle surface
62
at the inner wall
63
of the portion of the receptacle
4
having a greater diameter.
In the end position of the control valve piston
2
illustrated in
FIG. 9
, the depression or recess
65
provides a connection between the bore
47
in the housing wall
49
and the bore
55
in the control valve piston
2
. The pressure line
10
is connected at the radial inner end to an annular channel
66
which is provided in the inner wall
63
of the receptacle
4
. This annular channel
66
is of such an axial length that in the end position of the control valve piston
2
according to
FIG. 9
the bore
55
is in communication with the annular channel
66
.
When the coil
54
is no longer supplied with current, the armature base plate
50
is moved by the pressure spring
51
in the direction toward the housing wall
49
.
Accordingly, the valve element
48
is moved into its closed position in which it closes the bore
47
in the housing wall
49
relative to the receptacle
52
. The annular surface
67
surrounding the projection
64
of the control valve piston
2
has a larger surface area than a radially positioned annular surface
68
of the collar
59
of the control valve piston
2
. Accordingly, the pressure of the hydraulic medium flowing from the pressure line
10
to the pressure chamber
15
and acting on the annular surface
68
is smaller than the pressure exerted by the pressure medium onto the annular surface
67
. The control valve piston
2
is thus reliably moved back into the initial position according to FIG.
8
. When this occurs, first the pressure line
10
is closed by the conical surface
61
of the control valve piston
2
. Subsequently, the annular chamber
56
is relieved in the direction to the tank. This temporal sequence is achieved by overlap of the conical surface
61
with a corresponding edge of the pressure line
10
.
The throttle
65
in the projection
64
of the control valve piston
2
ensures that the control valve piston
2
can be reliably returned from its contact position at the housing wall
49
. The flow cross-section of the throttle
65
is larger than the flow cross-section of the annular channel
66
. This ensures that upon closing of the valve element
48
a sufficiently high pressure is built up in the pressure chamber
46
before the control valve piston
2
in order to move the piston
2
back in the described way.
The control valve
1
according to
FIGS. 8 and 9
enables a very quick switching. For example, the control valve piston
2
requires for its complete stroke a switching time of less than 200 μs. The valve comprised of bore
47
, valve element
48
and acting as a pilot valve is also suitable for piston valves with solenoids corresponding to the preceding embodiments. It is moreover possible to actuate the pilot valve (
47
,
48
) also with piezoelectric or magnetorestrictive, actively operated valves. The return element for the valve element
48
can also be a tube spring or any other type of spring of a suitable configuration.
The armature base plate
50
is formed as a flat armature with which very high forces and high accelerations can be achieved.
FIG. 11
shows an embodiment which is substantially identical to the embodiment according to FIG.
1
. The control valve piston
2
is loaded at both ends with a pressure spring
69
,
70
, respectively, so that the control valve piston
2
assumes a central position when the corresponding coils
8
,
9
are not excited. This defined central position of the control valve piston
2
ensures that the intake/exhaust valve
21
,
22
will not completely open but will assume a central position so that a correspondingly smaller amount of air/fuel mixture is conveyed into the combustion chamber
24
. In order to reach this central position, first one coil
8
or
9
is supplied with current in the way described above so that the control valve piston
2
is moved in the corresponding direction. As soon as the desired smaller opening cross-section has been reached, the current supply of this coil is terminated so that the control valve piston
2
is secured in the central position by the two pressure springs
69
,
70
. Accordingly, the intake/exhaust valve
21
,
22
remains in its central position. In this way, the intake/exhaust valve
21
,
22
can be moved into three positions, i.e., a closed position, a half-open position, and a completely open position.
Instead of the coils
8
,
9
to be supplied with current, the actuating elements for the control valve piston
2
can be, for example, piezoelectric actuators or piezoelectric elements. It is also possible to employ magnetorestrictive switching elements.
The bushing
3
of the different embodiments in which the control valve piston
2
is slidably supported is not necessarily required.
In order to improve the switching movement of the control valve piston
2
, it is possible, for example, in the embodiment according to
FIG. 1
, to provide a permanent magnet in addition to the solenoid with the coil
8
. In this configuration the control valve piston
2
is secured in the respective end position by the magnetic force of this permanent magnet when the coil
8
is not supplied with current. This coil is configured such that the magnetic field resulting when it is excited cancels the magnetic field of the permanent magnet. In order to be able to move the control valve piston
2
quickly, both coils
8
,
9
are supplied with current. Since the excitation of the coil
8
cancels the magnetic field of the permanent magnet, the control valve piston
2
is quickly pulled because at the opposite side a counter force which would otherwise be provided by the permanent magnet is not present.
In the embodiment according to
FIG. 11
, the position of the control valve piston
2
when the coils
8
and
9
are not excited can be adjusted, on the one hand, and the acceleration of the control valve piston
2
and thus its switching behavior can be affected, on the other hand, by the proper selection of the two pressure springs
69
,
70
. As a result of this arrangement, an optimized configuration of the control valve or of the entire actuating device for the intake/exhaust valve
21
,
22
can be provided.
The switching behavior described with the above embodiments can be used for different purposes, for example, for an injection device of an internal combustion engine of a motor vehicle.
As a result of the described configuration, very high acceleration values can be obtained with the control valve piston
2
. For example, the control valve piston
2
can be moved, for example, with a speed of approximately 400 μs from one into the other switching position. When the control valve piston
2
is loaded additionally by the pressure springs
69
,
70
, the switching velocity can be increased even more.
For the described control devices an electronic control is used which sets the switching cycles. The electronic control enables in connection with the control devices completely new possibilities of motor control, such as cylinder turn-off or the optimization of idle operation of the engine and of the fuel consumption. Also, closing or partial opening of the valves can be used for controlling the engine brake function. The combustion process can be optimized by controlling the fuel/air mixture supply and thus the pollutant emissions can be improved. As a result of the described active control of the control devices quiet running properties of the engine are considerably improved.
Possible valve discontinuities can be compensated by electronic devices and software. The start-up and/or the stopping behavior of the control valve piston
2
can be optimized by linearizing the piston movement. In the control devices with coils
8
,
9
, the counter inductivity of the inactive coil can be used for determining the actual piston movement (sensor as a feedback) and thus for controlling and governing the control valve piston
2
. Also, further coil windings or an additional travel sensor can be employed for controlling and governing the control valve piston
2
. The control of the control valve piston
2
allows the realization of partial strokes which provide an exact repetition behavior for precise control of the intake/exhaust valves
21
,
22
.
The relief bores or tank connectors T are configured such that draining of the hydraulic medium from the control valve piston chamber is prevented. This is achieved, for example, in that a rising line is provided. In this way, it is ensured that the hydraulic medium level (static hydraulic medium level) is above the control valve piston
2
so that ambient air cannot penetrate into the control valve
1
. In this way, the precision from switching to switching can be significantly improved. If air were to enter the control valve, it would be compressed so that the switching behavior would deteriorate considerably.
It is also possible to pre-load the return hydraulic medium with pressure in order to maintain the conditions within the control valve
1
constant. In order to maintain pressure within the return hydraulic medium simple pre-loaded plates or seat valves with springs can be used. This also prevents air from entering the control valve
1
.
While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.
Claims
- 1. A control device for switching an intake or exhaust valve of an internal combustion engine, the control device comprising:a control valve comprising a control valve piston configured to control flow of a hydraulic medium from a pressure line to the intake or exhaust valve; at least one actuating element correlated with the intake or exhaust valve and having a first end acted on by the hydraulic medium; at least one damping device interacting with the at least one actuating element and arranged at a second end of the actuating element opposite the first end, wherein the at least one damping device is configured to exert a damping force onto the actuating element counteracting a force exerted by the hydraulic medium; wherein the control valve has a first pressure chamber located at a first end of the control valve piston and a second pressure chamber communicating with the first pressure chamber via a bore, wherein a valve element is provided and has a closing position for closing off the bore.
- 2. The control device according to claim 1, wherein the damping device comprises at least one pressure spring.
- 3. The control device according to claim 1, wherein the damping force of the damping device is a hydraulic force.
- 4. The control device according to claim 3, wherein the damping device comprises at least one supply line for a hydraulic damping medium, wherein the supply line is configured to be closed off by the actuating element when the actuating element moves into an end position.
- 5. The control device according to claim 4, wherein the actuating element is a bucket tappet.
- 6. The control device according to claim 1, wherein the control valve piston is configured to be moved electromagnetically.
- 7. The control device according to claim 6, further comprising a pilot valve configured to actuate the control valve piston.
- 8. The control device according to claim 7, wherein the pilot valve is a piezoelectric or magnetorestrictive, actively operated valve.
- 9. The control device according to claim 1, wherein the control valve further comprises a first coil, a second coil, and a valve housing, wherein the first and second coils are arranged in the valve housing in areas where opposed ends of the control valve piston are positioned.
- 10. The control device according to claim 9, wherein the control valve piston is configured to be secured in a first end position by residual magnetism.
- 11. The control device according to claim 1, wherein the control valve piston and the actuating element are positioned atop one another and are spaced from one another.
- 12. The control device according to claim 1, wherein the control valve piston is arranged at a spacing adjacent to the intake or exhaust valve.
- 13. The control device according to claim 1, wherein the switching valve comprises an armature element configured to secure the valve element in the closing position.
- 14. The control device according to claim 13, wherein the armature element further comprises a pressure spring acting on the armature element, wherein the armature element is configured to be moved counter to the pressure spring.
- 15. The control device according to claim 1, wherein the control valve piston has a supply line configured to connect the pressure line to the first pressure chamber.
- 16. The control device according to claim 15, wherein the control valve piston has an end face delimiting the first pressure chamber and wherein the end face has at least one throttle connecting the first pressure chamber to the supply line of the control valve piston when the end face of the control valve piston contacts an oppositely arranged wall of the pressure chamber.
- 17. The control device according to claim 15, wherein the control valve piston has an annular channel located at a transition of the supply line to the pressure line.
- 18. The control device according to claim 16, wherein the end face of the control valve piston delimiting the first pressure chamber is a first annular surface and wherein the control valve piston has a second annular surface facing away from the first annular surface and configured to be loaded by the hydraulic medium supplied via the pressure line, wherein the first annular surface is greater than the second annular surface.
- 19. The control device according to claim 1, wherein the control valve has at least one magnet configured to secure the control valve piston in at least one end position.
- 20. The control device according to claim 1, wherein the control valve has at least three switching positions.
- 21. The control device according to claim 1, further comprising a valve bushing configured to adjust the switching valve.
- 22. The control device according to claim 1, wherein the control valve further comprises a first coil, a second coil, and a valve housing, wherein the first and second coils have carriers and are secured in the valve housing by welding the carriers to the valve housing in areas where ends of the control valve piston are positioned.
- 23. A control device for switching an intake or exhaust valve, of an internal combustion engine, the control device comprising:a control valve comprising a control valve piston configured to control flow of a hydraulic medium from a pressure line to the intake or exhaust valve; at least one actuating element correlated with the intake or exhaust valve and having a first end acted on by the hydraulic medium; at least one damping device interacting with the at least one actuating element and arranged at a second end of the actuating element opposite the first end, wherein the at least one damping device is configured to exert a damping force onto the actuating element counteracting a force exerted by the hydraulic medium; wherein the control valve has relief bores configured such that the control valve piston is surrounded by the hydraulic medium and ambient air cannot penetrate into the control valve.
- 24. The control device according to claim 23, wherein the hydraulic medium to be returned is pre-loaded.
Priority Claims (1)
Number |
Date |
Country |
Kind |
100 49 698 |
Oct 2000 |
DE |
|
US Referenced Citations (9)