U.S. patent application number 10/532381 was filed with the patent office on 2006-06-29 for arrays for controllable power supply of electrovalves of an electrohydraulic valve control.
Invention is credited to Heman Gaessler, Ulf Pischke, Hubert Schweiggart.
Application Number | 20060137633 10/532381 |
Document ID | / |
Family ID | 32115110 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060137633 |
Kind Code |
A1 |
Schweiggart; Hubert ; et
al. |
June 29, 2006 |
Arrays for controllable power supply of electrovalves of an
electrohydraulic valve control
Abstract
An arrangement for supplying current to the solenoid valves of
an electrohydraulic valve-timing system of an internal combustion
engine in a controllable manner has solenoid valves assigned to the
gas-exchange actuators. A two-stage supplying of voltage is
provided for the solenoid valves, namely the supplying of an inrush
voltage from an inrush voltage source, and the supplying of a
holding voltage from a holding voltage source. In this context, the
inrush voltage is greater than the holding voltage. The solenoid
valves can be actuated independently of one another for the
duration of an inrush current time by an inrush current that
corresponds to the applied inrush voltage, and for the duration of
a holding current time by a holding current that corresponds to the
applied holding voltage. For each solenoid valve, one holding
voltage line and one inrush voltage line are provided, which
connect the solenoid valve to the holding voltage source and to the
inrush voltage source, respectively. From each solenoid valve, a
ground lead leads to ground, a ground lead disconnector being
provided in the ground lead for switchably disconnecting the
electrical connection between the solenoid valve and ground.
Inventors: |
Schweiggart; Hubert;
(Stuttgart, DE) ; Pischke; Ulf; (Stuttgart,
DE) ; Gaessler; Heman; (Vaihingen, DE) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
32115110 |
Appl. No.: |
10/532381 |
Filed: |
May 27, 2003 |
PCT Filed: |
May 27, 2003 |
PCT NO: |
PCT/DE03/01718 |
371 Date: |
September 6, 2005 |
Current U.S.
Class: |
123/90.12 ;
123/90.15 |
Current CPC
Class: |
F01L 9/20 20210101; F01L
9/10 20210101 |
Class at
Publication: |
123/090.12 ;
123/090.15 |
International
Class: |
F01L 9/02 20060101
F01L009/02; F01L 1/34 20060101 F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 2002 |
DE |
10251034.2 |
Claims
1-21. (canceled)
22. A system for supplying current to a plurality of solenoid
valves of an electrohydraulic valve-timing system of an internal
combustion engine in a controllable manner, the plurality of
solenoid valves being assigned to a gas-exchange actuator, a
two-stage voltage supply being provided for the solenoid valves,
the two-stage voltage supply including an inrush voltage from an
inrush voltage source and a holding voltage from a holding-voltage
source, the inrush voltage being greater than the holding voltage,
the system comprising: an inrush voltage line and an a holding
voltage line provided for each solenoid valve, the inrush voltage
line connecting the respective solenoid valve to the inrush voltage
source and the holding voltage line connecting the respective
solenoid valve to the holding voltage source, wherein each solenoid
valve is configured to be actuated independently of other solenoid
valves for the duration of an inrush current time by an inrush
current that corresponds to the inrush voltage, and for the
duration of a holding current time by a holding current that
corresponds to the holding voltage; a ground lead switch provided
for each solenoid valve and configured to at least one of
selectively connect and disconnect an electrical connection between
the respective solenoid valve and ground; and a voltage switch,
wherein a solenoid valve group is formed from at least two solenoid
valves, and wherein the inrush voltage lines leading to the
solenoid valves of the solenoid valve group have a common
inrush-voltage circuit section, the voltage switch being provided
in the common inrush-voltage circuit section for at least one of
selectively connecting and disconnecting electrical connection
between the inrush-voltage source and the solenoid valves of the
solenoid valve group.
23. The system according to claim 22, wherein the holding voltage
lines leading to the solenoid valves of the solenoid valve group
share a common holding-voltage circuit section, and are configured
to permanently supply the solenoid valves of the solenoid valve
group with the holding voltage.
24. The system according to claim 23, wherein the voltage switch
selectively connects and disconnects the common inrush-voltage
circuit section to the common holding-voltage circuit section of
the solenoid valve group at a junction point, and wherein a diode
is provided in the common holding-voltage circuit section between
the holding voltage source and the junction point, the diode
blocking the current flow from the junction point to the holding
voltage source, and wherein the inrush voltage and the holding
voltage are provided over a common circuit path from the junction
point to the solenoid valves of the solenoid valve group.
25. The system according to claim 24, wherein the solenoid valves
of the solenoid valve group are configured in such a way that there
is no overlapping of inrush-voltage actuation times with
holding-voltage actuation times.
26. The system according to claim 25, wherein the ground lead
switches of the solenoid valves of the solenoid valve group are
each switchable in a clocked operation cycle, wherein a
make-to-break ratio is selected such that when the inrush voltage
is supplied the average current flow resulting from the clocked
operation corresponds to the holding current derived in response to
application of the holding voltage.
27. The system according to claim 25, wherein each solenoid valve
of the solenoid valve group has a feedback line on the ground
connection side, the feedback line connecting the ground connection
of the respective solenoid valve to the inrush voltage source, and
wherein a diode is provided in each feedback line, the diode
blocking a current flow from the inrush voltage source to the
ground connection of the respective solenoid valve.
28. The system according to claim 25, wherein at least one intake
valve and at least one exhaust valve are provided for each cylinder
of the internal combustion engine, each of the intake and exhaust
valves being actuated by a gas-exchange actuator, and wherein the
gas-exchange actuator includes a first solenoid valve and a second
solenoid valve, the first solenoid valve being closed in a
de-energized state, and the second solenoid valve being opened in a
de-energized state.
29. The system according to claim 28, wherein all of the solenoid
valves of one cylinder of the internal combustion engine are
combined into one solenoid valve group.
30. The system according to claim 28, wherein, for at least two
cylinders of the internal combustion engine, solenoid valves
assigned to the intake valves are combined into a first solenoid
valve group, and solenoid valves assigned to the exhaust valves are
combined into a second solenoid valve group.
31. The system according to claim 30, wherein the at least two
cylinders are selected from the cylinders of the internal
combustion engine such that no overlapping of inrush-voltage
actuation time with holding-voltage actuation time occurs within
the solenoid valve groups.
32. The system according to claim 28, wherein, for one cylinder
group including a plurality of cylinders of the internal combustion
engine, all first solenoid valves of the intake valves are
connected to form a first solenoid valve group, all first solenoid
valves of the exhaust valves are connected to form a second
solenoid valve group, and all second solenoid valves of the
gas-exchange actuators are connected to form a third solenoid valve
group.
33. The system according to claim 32, wherein one cylinder group is
formed which contains all cylinders of the internal combustion
engine.
34. The system according to claim 32, wherein at least two cylinder
groups are formed for the internal combustion engine, one cylinder
group containing all cylinders of one cylinder bank.
35. The system according to claim 32, wherein at least two cylinder
groups are formed for the internal combustion engine, each cylinder
group including a plurality of cylinders, and wherein the cylinders
of the one cylinder group are selected such that, within the
solenoid valve groups of the cylinder groups, no overlapping
between inrush-voltage actuation time and holding-voltage actuation
time occurs.
36. A system for supplying current to solenoid valves of an
electrohydraulic valve-timing system of an internal combustion
engine in a controllable manner, the solenoid valves being assigned
to a gas-exchange actuator and being supplied with a holding
voltage from a holding voltage source and an inrush voltage from an
inrush voltage source, the system comprising: an inrush voltage
line provided for each solenoid valve, the inrush voltage line
connecting the solenoid valve to the inrush voltage source, wherein
the solenoid valves are configured to be actuated independently of
one another; a ground lead leading from each solenoid valve to
ground, the ground lead having one ground lead switch for at least
selectively connecting and disconnecting an electrical connection
between the solenoid valve and ground; an inrush voltage line
provided for each solenoid valve, the inrush voltage line
connecting the respective solenoid valve to the inrush voltage
source, wherein a solenoid valve group is formed from a plurality
of solenoid valves, and wherein the inrush voltage lines leading to
the solenoid valves of the solenoid valve group have a common
inrush-voltage circuit section; and a voltage switch provided in
the common inrush-voltage circuit section for at least one of
selectively connecting and disconnecting an electrical connection
between the inrush voltage source and the solenoid valves of the
solenoid valve group by timed switching of the voltage switch using
a selected make-to-break ratio, wherein an average voltage produced
corresponds to the holding voltage, and wherein the solenoid valves
of the solenoid valve group are selected such that there is no
overlapping of inrush-voltage actuation times with holding-voltage
actuation times.
37. The system according to claim 36, wherein each solenoid valve
has a feedback line on a ground-connection side, the feedback line
connecting a ground connection of the respective solenoid valve to
the inrush voltage source, and wherein a diode is provided in the
feedback line, the diode blocking a current flow from inrush
voltage source to the ground connection of the respective solenoid
valve.
38. The system according to claim 36, wherein at least one intake
valve and at least one exhaust valve are provided for each cylinder
of the internal combustion engine, each of the intake and exhaust
valves being actuated by a gas-exchange actuator, and wherein the
gas-exchange actuator includes a first solenoid valve and a second
solenoid valve, the first solenoid valve being closed in a
de-energized state, and the second solenoid valve being opened in a
de-energized state.
39. The system according to claim 36, wherein all of the solenoid
valves of one cylinder of the internal combustion engine are
combined into one solenoid valve group.
40. The system according to claim 36, wherein, for at least two
cylinders of the internal combustion engine, solenoid valves
assigned to the intake valves are combined into a first solenoid
valve group, and solenoid valves assigned to the exhaust valves are
combined into a second solenoid valve group.
41. The system according to claim 40, wherein one cylinder group is
formed which contains all cylinders of the internal combustion
engine.
42. The system according to claim 40, wherein at least two cylinder
groups are formed for the internal combustion engine, one cylinder
group containing all cylinders of one cylinder bank.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to an arrangement for
supplying current to the solenoid valves of an electro-hydraulic
valve-timing system of an internal combustion engine in a
controllable manner.
BACKGROUND INFORMATION
[0002] In known electrohydraulic valve-timing systems, solenoid
valves are assigned to gas-exchange actuators. The solenoid valves
are energized in order to control the flow of hydraulic oil to and
from the gas-exchange actuator. In this context, it is known to
provide a two-stage voltage supply for the solenoid valves. An
inrush voltage is supplied by an inrush voltage source, and a
holding voltage is supplied by a holding-voltage source, the inrush
voltage being greater than the holding voltage. The actuation of
the solenoid valve in response to the application of the inrush
voltage leads to a rapid acceleration of the valve body. In this
way, the valve's inertia is reduced. Following a free-running phase
subsequent to the actuation by the inrush voltage, the solenoid
valve is actuated by the holding voltage. The holding voltage is of
sufficient magnitude to reliably bring the valve body into the end
actuation position of the valve, and to hold it there. However,
compared to the inrush voltage, the current consumption in the
holding phase is lower. As a result, there is also less
self-heating of the valve. The solenoid valves can be actuated
independently of one another for the duration of an inrush current
time by an inrush current that corresponds to the applied inrush
voltage, and for the duration of a holding current time by a
holding current that corresponds to the applied holding voltage.
Thus, the duration of actuation of the solenoid valve is derived
from the inrush current time, the time subsequent thereto for the
free-running phase, and from the holding current time. In this
context, the solenoid valve can be designed both as a normally-open
as well as a normally-closed valve. If the solenoid valve is
designed as a normally-open valve, then it interrupts a fluid path
when energized, while a valve designed as a normally-closed valve
clears a fluid path when actuated. In this context, one holding
voltage line and one inrush voltage line are provided for each
solenoid valve, the holding voltage line connecting the solenoid
valve to the holding voltage source and the inrush voltage line
connecting the solenoid valve to the inrush voltage source.
Moreover, a ground lead leading from the solenoid valve to ground
is provided, having one ground lead disconnector for switchably
disconnecting the electrical connection between the solenoid valve
and ground.
[0003] In the above-described arrangement, besides the ground lead
disconnector, for each solenoid valve, a changeover switch is also
necessary to connect the solenoid valve alternatively to the inrush
voltage line or to the holding voltage line.
[0004] To actuate a gas-exchange valve, the solenoid valves
assigned to this gas-exchange valve are driven. In the process, the
controlled actuation of the changeover switch and of the ground
lead disconnector is required to drive a solenoid valve. The
electric power supply to the particular solenoid valve is switched
via the ground lead disconnector, while the inrush voltage or the
holding voltage is alternately applied to the solenoid valve via
the changeover switch.
[0005] A gas-exchange valve is typically controlled via two
solenoid valves; one determines the supply of hydraulic fluid into
a working chamber, and the other controls the discharge of the
hydraulic fluid out of the working chamber. If an internal
combustion engine has four gas-exchange valves (two intake valves
and two exhaust valves) per cylinder, then eight solenoid valves
and thus sixteen separately controllable switches are needed just
to control one cylinder. An equivalent number of driving signals
for actuating the solenoid valves must be generated
time-synchronously to move the crankshaft.
[0006] It is an object of the present invention to reduce the
outlay required for circuitry and for control of solenoid
valves.
SUMMARY
[0007] An arrangement for supplying current to the solenoid valves
of an electrohydraulic valve-timing system of an internal
combustion engine in a controllable manner has solenoid valves
assigned to the gas-exchange actuators. A two-stage supplying of
voltage is provided for the solenoid valves, namely the supplying
of an inrush voltage from an inrush voltage source, and the
supplying of a holding voltage from a holding voltage source. In
this context, the inrush voltage is greater than the holding
voltage. The solenoid valves may be actuated independently of one
another for the duration of an inrush current time by an inrush
current that corresponds to the applied inrush voltage, and for the
duration of a holding-current time by a holding current that
corresponds to the applied holding voltage. For each solenoid
valve, one inrush voltage line and one holding voltage line are
provided, which connect the solenoid valve to the inrush voltage
source and to the holding voltage source, respectively. From each
solenoid valve, a ground lead leads to ground, a ground lead
disconnector being provided in the ground lead for switchably
disconnecting the electrical connection between the solenoid valve
and ground.
[0008] In accordance with the present invention, a solenoid valve
group is formed from a plurality of solenoid valves. Inrush voltage
lines leading to the solenoid valves of a solenoid valve group have
a common inrush-voltage circuit section, and a voltage disconnector
is provided in the common inrush-voltage circuit section for
establishing the switchable electrical connection between the
inrush voltage source and the solenoid valves of the solenoid valve
group.
[0009] As a result of this arrangement, only one single switchable
voltage disconnector needs to be provided for the solenoid valves
of the solenoid valve group to establish the connection to the
inrush voltage. This single voltage disconnector replaces the
changeover switch that is provided for each valve. If the voltage
disconnector is switched through, then the inrush voltage is
applied to all solenoid valves of the solenoid valve group. The
actual energizing of the solenoid valve with the inrush current
derived from the inrush voltage is accomplished by the actuation of
the individual ground lead disconnectors assigned to the solenoid
valves. A solenoid valve is energized with inrush current when the
voltage disconnector of the corresponding solenoid valve group is
closed and, at the same time, when the corresponding ground lead
disconnector of the solenoid valve is likewise closed. Due to the
existence of the ground lead disconnector, the solenoid valves
within the solenoid valve group continue to be individually
controllable.
[0010] Thus, the present invention makes it possible to reduce the
number of required switches. Along with the reduction in the number
of switches, the outlay for controlling the switches is also
correspondingly reduced. Due to the presence of a common
inrush-voltage circuit section, the outlay for circuit wiring is
also reduced.
[0011] In accordance with one example embodiment of the present
invention, the holding-voltage line is designed to permanently
supply the solenoid valves of at least one solenoid valve group
with holding voltage. In this context, the holding voltage lines
leading to the solenoid valves have a common holding voltage
section. This measure reduces the outlay for circuit wiring.
[0012] In accordance with another example embodiment, the voltage
disconnector of a solenoid valve group connects the common inrush
voltage section to the common holding voltage section of this
solenoid valve group at a contact point. In this context, a
blocking diode is provided in the common holding voltage section
between the holding voltage source and the junction point. It
blocks the current flow from the junction point to the holding
voltage point. A common line for supplying the corresponding
solenoid valve with inrush voltage and with holding voltage leads
from the junction point to the solenoid valves of the solenoid
valve group. This measure further reduces the outlay for circuit
wiring. The inrush voltage and holding voltage may be supplied, in
part, over the same line. If the voltage disconnector of a solenoid
valve group is interrupted, then the holding voltage is applied to
the solenoid valves. If the voltage disconnector is closed, then
the inrush voltage is applied to the solenoid valves. The diode
between the holding voltage source and the junction point source
prevents current from flowing from the inrush voltage source to the
holding voltage source and, thus, an undesired shunting. This
measure as well reduces the outlay required for cabling or circuit
wiring.
[0013] The solenoid valves of a solenoid valve group are energized
by the inrush current derived from the inrush voltage when the
voltage disconnector is closed and, at the same time, when the
ground lead disconnector assigned to the individual valve is
likewise closed. A solenoid valve is actuated by the holding
current derived from the holding voltage when the voltage
disconnector of the solenoid valve group is disconnected and the
ground lead disconnector assigned to the corresponding solenoid
valve is closed.
[0014] In accordance with one example embodiment of the present
invention, the solenoid valves of a solenoid valve group are
selected in such a way that the inrush-voltage actuation times do
not overlap with the holding-voltage actuation times. This measure
ensures that when it is necessary to supply one solenoid valve of
the solenoid valve group with inrush voltage, that it is not
necessary to supply another valve with holding voltage.
Alternatively, either the inrush voltage or the holding voltage is
applied to the voltage supply side of the solenoid valves. If there
is no overlapping of the holding current times and the inrush
current times, then the voltage disconnector may be suitably
actuated to effect that the voltage level required at the
particular instant is applied to the voltage side of the solenoid
valves.
[0015] In a classic valve-timing mechanism, the opening angular
ranges of the gas-exchange valves over the crankshaft angle are, at
a maximum, 240.degree. crankshaft angle. This considers both the
opening times of the intake valves as well as of the exhaust
valves. Accordingly, at a maximum, this is proportionally 33% of an
engine's working cycle of over 720.degree. crankshaft angle, so
that it is easily possible to combine a plurality of solenoid
valves into one solenoid valve group, without the occurrence of any
corresponding overlapping.
[0016] In accordance with one example embodiment of the present
invention, the ground lead disconnector of the solenoid valves is
switchable in a clocked cycle. In this context, the make-to-break
ratio is devised in such a way that when inrush voltage is
supplied, the average current flow resulting from the clocked
operation corresponds to the holding current derived from the
holding voltage. Thus, by the timed switching of the ground lead
disconnector, power may also be supplied using a current
corresponding to the holding current when the inrush voltage is
applied on the voltage-supply side. This measure is particularly
advantageous when, within solenoid valves assigned to one solenoid
valve group, an overlapping results between inrush-voltage
actuation times and holding-voltage actuation times. However, it
may also be utilized to reduce the number of switching operations
of the voltage disconnector and to partially allow the inrush
voltage to be applied on the voltage supply side even when it would
actually suffice for just holding voltage to be supplied. In
accordance with another example embodiment of the present
invention, on the ground connection side, each solenoid valve has a
feedback line which connects the ground connection of the solenoid
valve to the inrush voltage source. In this context, a diode is
connected in the feedback line. It blocks a current flow from the
inrush voltage source to the ground connection of the solenoid
valve.
[0017] The advantage of this example embodiment of the present
invention is that the currents flowing in the coil of a solenoid
valve are able to be quickly reduced once the ground lead
disconnector is opened. Simply stated, current is fed back via the
feedback line to the inrush-voltage source. The diode situated in
the feedback line prevents current from flowing from the inrush
voltage source via the feedback line to the solenoid valve and,
from there, to the holding voltage source. If a solenoid valve is
actuated by an inrush current because the voltage disconnector was
closed, then, in response to opening of the ground lead
disconnector, the decaying coil current may flow back to the inrush
voltage source. In between applications of in-rush current and
holding current to the solenoid valve, the so-called free-wheeling
or free-running phase is generated. In this free-running phase, the
ground lead disconnector of the corresponding solenoid valve is
opened. Similarly, a rapid extinguishing of current results, so
that the solenoid valve is quickly moved back at the end of the
holding phase predefined by the holding current time. If, in
response to the application of holding voltage, the ground lead
disconnector of a solenoid valve is opened, the still present coil
current may only be fed back via the feedback line to the voltage
source, which is at a higher potential than the holding voltage
source. The result is a rapid decay of the coil current.
[0018] In accordance with one example embodiment of the present
invention, first and second solenoid valves are provided, the first
solenoid valves being closed in a de-energized state, and the
second solenoid valves being opened in a de-energized state. As an
example, each gas-exchange actuator has a first and a second
solenoid valve. Each cylinder of the internal combustion engine
has, e.g., at least one intake valve and at least one exhaust
valve, each of the intake and exhaust valves being able to be
actuated by a gas-exchange actuator. A complete electrohydraulic
valve actuation is accomplished by this arrangement.
[0019] In accordance with one example embodiment of the present
invention, all solenoid valves of the gas-exchange actuators
assigned to one cylinder of the internal combustion engine are
combined into one solenoid valve group.
[0020] By combining into one solenoid valve group, all solenoid
valves which are assigned to one cylinder because of their
allocation to the gas-exchange actuators form a solenoid valve
group for which it is ensured that the time periods during which
the solenoid valves are actuated by inrush voltage do not overlap
with those periods during which they are actuated by holding
voltage.
[0021] Given a reduced number of control elements and a reduced
outlay for actuation, such an arrangement renders possible a valve
control that is free of overlap times, even in the context of
internal combustion engines having a large number of cylinders.
[0022] In accordance with one example embodiment of the present
invention, for at least two cylinders of the internal combustion
engine in each case, the solenoid valves assigned to the intake
valves are combined into a first solenoid valve group, and the
solenoid valves assigned to the exhaust valves are combined into a
second solenoid valve group. Compared to an approach where all
solenoid valves of one cylinder of the internal combustion engine
are combined into one solenoid valve group, this makes it possible
to further reduce the number of controllable switches and the
corresponding outlay for control lines, without the occurrence of
overlap times. For example, in the case of a four-cylinder engine,
which, in each case, at one cylinder, has two exhaust valves and
two intake valves having two solenoid valves each, a design
approach involving individual solenoid valves requires 32 ground
lead disconnectors and also 32 changeover switches between the
inrush voltage source and the holding voltage source. When the four
solenoid valves of the intake valves and the four solenoid valves
of the exhaust valves are combined into one solenoid valve group
each, compared to the previously required eight changeover
switches, only two voltage disconnectors are required; the number
of corresponding switches and necessary diodes is likewise reduced
correspondingly.
[0023] If for two cylinders, eight solenoid valves which are
assigned to the intake valves and eight solenoid valves which are
assigned to exhaust valves of the cylinders are combined into one
solenoid valve group, then only 1/8 of the voltage disconnectors
are needed, as are any existing diodes in feedback lines. The
result is a further reduction in the outlay for design and
assembly. If the solenoid valves of more than two cylinders are
combined into solenoid valve groups, then a further reduction in
the outlay for design and assembly may be achieved. However, in
some instances, one then has to accept the occurrence of overlap
times during which, on the one hand, it would be necessary to
supply one solenoid valve of a solenoid valve group with inrush
voltage and, on the other hand, to supply another solenoid valve of
the same solenoid valve group with holding voltage. However, three
suitably selected cylinders of one six-cylinder engine may be
combined into one solenoid valve group still without any or with
only very few overlap times. If overlap times occur, then a timed
switching of the ground lead disconnectors must be utilized for
these time periods. Nevertheless, in such an embodiment, the
advantages of reduced costs because of the reduced number of
required diodes and required voltage disconnectors may outbalance
the disadvantages of the resulting requirement for a timed
switching of the ground lead disconnectors.
[0024] In accordance with one example embodiment of the present
invention, the at least two cylinders are selected from the
cylinders of the internal combustion engine in such a way that no
overlapping of inrush-voltage actuation time and holding-voltage
actuation time occurs within the solenoid valve group.
[0025] In accordance with one example embodiment of the present
invention, one cylinder group is formed in each instance from a
plurality of cylinders of the internal combustion engine. For one
cylinder group, all first solenoid valves--which are closed in a
de-energized state--of the intake valves are combined into a first
solenoid valve group, and all first solenoid valves--which are
closed in a de-energized state--of the exhaust valves are combined
in a second solenoid valve group, and all second solenoid
valves--which are closed in a de-energized state--of the
gas-exchange valves are combined into a third solenoid valve group.
It is customary for a gas-exchange actuator, thus for an intake
valve or an exhaust valve, to have a first solenoid valve, which is
closed in a de-energized state and which controls the inflow of
pressurized hydraulic fluid into the working chamber of the
hydraulic actuator. Situated at the exhaust side of the hydraulic
actuator is a second solenoid valve that is opened in the
de-energized state. This design ensures that the working chamber of
the gas-exchange actuator is unpressurized in response to
de-energized solenoid valves. In this context, all cylinders of an
internal combustion engine may be combined into one cylinder group.
However, in accordance with one alternative example embodiment, it
may also be provided for at least two cylinder groups to be formed.
In such a case, one cylinder group would then contain all cylinders
of one cylinder bank. Another example embodiment provides for
forming at least two cylinder groups, each of a plurality of
cylinders, the cylinders of one cylinder group being selected in
such a way that, within the solenoid valve groups of the cylinder
groups, no overlapping of inrush-voltage actuation time and
holding-voltage actuation time occurs. In this context, each
cylinder group may contain the same number of cylinders.
[0026] Such an embodiment of the present invention makes it
possible to combine a large number of solenoid valves into one
solenoid valve group, without any overlapping of inrush-voltage
actuation times and of holding-voltage actuation times occurring.
For example, in the context of a four-cylinder engine, every eight
first solenoid valves of the intake valves, every eight first
solenoid valves of the exhaust valves, and every sixteen second
solenoid valves of all gas-exchange actuators are combined in each
instance into one solenoid valve group. Thus, for a four-cylinder
internal combustion engine, only three voltage disconnectors and
only three decoupling diodes are needed between the holding voltage
and the inrush voltage. Together with the 32 ground lead
disconnectors that this yields, in a four-cylinder internal
combustion engine of this kind, only 35 switches are needed, and
only 35 driving signals need to be generated. This also
substantially reduces the necessary number of timing channels on
the part of the control unit and the outlay required for the
processing unit of the control unit.
[0027] In accordance with one alternative example embodiment of the
present invention, the need may also be completely eliminated for a
holding voltage source. As a result, the device makes do with one
single voltage source. The outlay is further reduced. This is
achieved in accordance with the present invention in that, in order
to supply the holding voltage, the voltage disconnector is switched
in a clocked cycle, the make-to-break ratio being selected in
accordance with the ratio between the holding voltage and the
inrush voltage. In this context, the solenoid valves of one
solenoid valve group are selected in such a way that no overlapping
of inrush-voltage actuation times and holding-voltage actuation
times occurs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows an example embodiment of an arrangement in
accordance with the present invention for energizing four solenoid
valves, which are assigned to two gas-exchange actuators.
[0029] FIG. 2 shows a schematic representation of the formation of
a solenoid valve group of all solenoid valves assigned to the
gas-exchange valves of a cylinder.
[0030] FIG. 3 shows a schematic representation of an example
embodiment having two valve groups, the first valve group combining
the solenoid valves of intake valves, and the second valve group
combining the solenoid valves of exhaust valves of two
cylinders.
[0031] FIG. 4 shows a schematic representation of an example
embodiment in which first solenoid valves and second solenoid
valves of gas-exchange actuators are combined in solenoid valve
groups that differ from one another.
DETAILED DESCRIPTION
[0032] In FIG. 1, an example circuit arrangement in accordance with
the present invention is shown for two gas-exchange valves Z1E1,
Z1E2. FIGS. 2 through 4 have been simplified in comparison to the
circuit arrangement shown in FIG. 1 to the effect that the shared
wire routing of holding-voltage line and of inrush voltage line via
shared circuit sections, as well as the feedback line, along with
the diode disposed therein, are no longer shown. The purpose of
FIGS. 2 through 4 is to illustrate how the solenoid valves of the
individual gas-exchange actuators are combined into solenoid valve
groups. In this context, the wiring configuration and the use of
shared circuit sections are possible in the example embodiments of
FIGS. 2 through 4 in the same way as in FIG. 1.
[0033] In the following descriptions of the figures, as well as in
the figures themselves, U.sub.A denotes the inrush voltage and
U.sub.H the holding voltage source. The gas-exchange actuators are
designated with respect to their property as intake valve or as
exhaust valve and their assignment to cylinders, and are each
schematically represented. Their designation includes the primary
symbol Z, with a subsequent numeral to designate the cylinder to
which they are assigned, the subsequent letter E or A, which
describes the assignment to the intake or exhaust valves of the
corresponding cylinder, and of a subsequent numeral which
distinguishes among the intake valves and among the exhaust valves
of a cylinder. The example embodiments of FIGS. 1 through 4 are
based on an internal combustion engine which has two intake and two
exhaust valves for each cylinder. Each gas-exchange actuator is
assigned a first solenoid valve denoted by M1 and a second solenoid
valve denoted by M2.
[0034] FIG. 1 shows an arrangement in which the two intake valves
Z1E1 and Z1E2 of first cylinder Z1 each have a first solenoid valve
M1 and a second solenoid valve M2. The two first solenoid valves M1
and the two second solenoid valves M2 are combined into one valve
group. Each of solenoid valves M1, M2 is assigned a ground lead
disconnector, which is situated in the electrical connection of the
particular solenoid valve M1, M2 to ground 12. From a junction
point 13, a holding-voltage line 14 leads in each instance to one
of solenoid valves M1, M2, so that each of the solenoid valves is
connected via a holding-voltage circuit section 14 to junction
point 13. A diode 16 is connected in series between junction point
13 and holding-voltage source U.sub.H in such a way that it
prevents current from flowing into holding voltage source U.sub.H.
Moreover, a shared inrush-voltage section 17, which, via a
controllable voltage disconnector 18, connects junction point 13 to
inrush voltage source U.sub.A, leads to the junction point. From
ground-side connection 19 of a solenoid valve M1, M2, one feedback
line 20 leads in each case back to inrush voltage source U.sub.A,
it being possible for circuit sections to be jointly used here as
well. Disposed in each feedback line 20 is a diode 21, which
prevents a short circuit current from inrush voltage source U.sub.A
to ground 12 via ground lead disconnector 11, or from inrush
voltage source U.sub.A via feedback line 20 and corresponding
solenoid valve M1, M2 and holding voltage section 14 back to
junction point 13.
[0035] To energize a solenoid valve within a half-bridge circuit,
it is necessary to close voltage disconnector 18 and ground lead
disconnector 11 assigned to solenoid valve M1, M2. Merely closing
voltage disconnector 18 does not produce any current flow through a
solenoid valve M1, M2. Thus, it is possible to interconnect all
solenoid valves of the group via the one voltage disconnector 18 of
the solenoid valve group. Solenoid valves M1, M2 may each be
energized just by closing ground lead disconnector 11.
[0036] The inrush voltage is switched in via voltage disconnector
18 to be able to start the solenoid valves in a highly dynamic
manner. However, the inrush voltage should be active only until the
valve armature undergoes its acceleration. After that, following a
free-running phase, the transition to a holding current is required
to keep the solenoid valve open to a specific degree. On the one
hand, energy savings are thereby achieved and, on the other hand,
the solenoid valves are prevented from overheating. In this
context, the extent to which the solenoid valves are energized may
be reduced by opening ground lead disconnector 11 assigned to the
solenoid valve or by opening voltage disconnector 18. In order for
a solenoid valve M1, M2 to be energized by a holding current
derived from the applied holding voltage, to the extent that the
inrush voltage is not needed for another solenoid valve, voltage
disconnector 18 is opened. On the voltage-input side, holding
voltage U.sub.H is then applied to the solenoid valves. In response
to closing of ground lead disconnector 11, the corresponding
solenoid valve is then energized by the holding current.
[0037] If an overlapping between energizing a solenoid valve M1, M2
with holding current and energizing with an inrush current occurs
when inrush voltage U.sub.A is applied to the voltage-side end of
another solenoid valve M1, M2 of the same valve group, then, by the
clocked driving of ground lead disconnector 11 of solenoid valve
M1, M2 which is to be operated with the holding current, given a
closed voltage disconnector 18, an average current flow is
generated corresponding to the holding current. In this context,
the make-to-break ratio between the closed and open ground lead
disconnector corresponds to the ratio of the holding voltage to the
inrush voltage.
[0038] An alternative example embodiment of the present invention
is provided by omitting diode 16 and holding-voltage source
U.sub.H. In such a case, the holding voltage is achieved by the
suitable timed switching of voltage disconnector 18. In this
context, the make-to-break ratio of the switch corresponds to the
ratio between the holding voltage and the inrush voltage. In such a
case, there must not be any overlap time between the inrush-voltage
actuation times and the holding-voltage actuation times.
[0039] In a simplified schematic representation, FIG. 2 shows the
grouping of solenoid valves M1, M2 of the two intake valves Z1E1
and Z1E2, as well as of the two exhaust valves Z1A1 and Z1A2 of a
first cylinder Z1 into a shared valve group. Shown in the drawing,
as well as in the other FIGS. 3 and 4, is gas-exchange actuator
Z1E1, Z1E2, Z1A1, Z1A2, in each instance below the two solenoid
valves M1, M2 assigned to it. A ground lead disconnector 11 leading
to ground 12 is assigned to each of solenoid valves M1, M2 of the
solenoid valve group. From holding-voltage source U.sub.H, shared
holding-voltage section 15, as well as holding-voltage sections 14
lead to solenoid valves M1, M2. In this context, diode 16, which
blocks current flow toward holding-voltage source U.sub.H, is
situated in the shared holding-voltage section 15.
[0040] FIG. 3 illustrates one example embodiment of the present
invention where intake valves Z1E1, Z1E2, Z2E1 and Z2E2 of the two
cylinders Z1 and Z2 are combined into a first valve group and are,
therefore, connected to first voltage disconnector 18a, while
solenoid valves M1, M2 of exhaust valves Z2A1, Z2A2, Z1A1 and Z1A2
of the two cylinders Z1 and Z2 are combined into a second valve
group and are connected to second voltage disconnector 18b. The two
voltage disconnectors are connected to inrush-voltage source
U.sub.A. Each solenoid valve group is also connected to
holding-voltage source U.sub.H, and, for reasons of simplicity, for
each cylinder Z1, Z2, a separate holding voltage source U.sub.H is
shown, which is protected by a diode 16 from backward flow of
current from solenoid valves M1, M2. Assigned to each of the
solenoid valves is a ground lead disconnector 11 which is used to
establish the switchable electrical connection to ground 12.
[0041] FIG. 4 shows another example embodiment where solenoid
valves M1, M2 are combined into three valve groups which differ
from one another and which each have an assigned voltage
disconnector 18a, 18b, 18c. The exemplary embodiment of FIG. 4 is
shown for two cylinders Z1, Z2, which have gas-exchange valves
Z1E1, Z1E2, Z1A1, Z1A2, Z2E1, Z2E2, Z2A1 and Z2A2. In the
arrangement of FIG. 4, still other cylinders may be added in the
same manner to the valve groups, but, for the sake of clarity, only
two cylinders Z1, Z2 are shown in the drawing. In the example
embodiment shown in FIG. 4, first solenoid valves M1 are assigned
to different solenoid valve groups than second solenoid valves M2.
Second solenoid valves M2 of all gas-exchange valves Z1E1, . . .
Z2A2 are combined into a common valve group, which is connected via
third voltage disconnector 18c to inrush-voltage source. Moreover,
first solenoid valves M1 of intake valves Z1E1, Z1E2, Z2E1 and Z2E2
are combined into a second valve group and are connected via second
voltage disconnector 18b to inrush-voltage source. The third valve
group is formed from first solenoid valves M1 of exhaust valves
Z1A1 . . . Z2A2 and is connected via first voltage disconnector 18a
to the inrush voltage source.
* * * * *