U.S. patent application number 13/135560 was filed with the patent office on 2012-09-27 for internal combustion engine with fan system.
Invention is credited to Karl Hagele, Markus Lechler.
Application Number | 20120240878 13/135560 |
Document ID | / |
Family ID | 46876247 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120240878 |
Kind Code |
A1 |
Hagele; Karl ; et
al. |
September 27, 2012 |
Internal combustion engine with fan system
Abstract
In an internal combustion engine cooling system, wherein a fan
with an adjustable cooling performance is provided with a fan wheel
having a hub with radial fan blades pivotally supported on the hub,
a control piston is disposed in the hub and connected to the blades
for the pivot position adjustment thereof over a range from a
suction position to a blowing position including a neutral position
in which the blades are oriented in a plane including the axis of
rotation of the fan wheel under the control of a control unit
causing movement of the piston for pivoting the blades to a
position for a cooling performance adjusted to the engine
requirements. The system is simple, safe and efficient and permits
counter flow operation of the fan for cleaning purposes.
Inventors: |
Hagele; Karl; (Schorndorf,
DE) ; Lechler; Markus; (Schorndorf, DE) |
Family ID: |
46876247 |
Appl. No.: |
13/135560 |
Filed: |
July 9, 2011 |
Current U.S.
Class: |
123/41.11 |
Current CPC
Class: |
F04D 29/362 20130101;
F01P 7/06 20130101 |
Class at
Publication: |
123/41.11 |
International
Class: |
F01P 7/02 20060101
F01P007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2011 |
DE |
10 2011 001 426.8 |
May 13, 2011 |
DE |
10 2011 101 494.6 |
Claims
1. An internal combustion engine with a fan system including a fan
wheel (1) having an adjustable cooling performance and an engine
control unit (50) providing control data for the cooling
performance of the fan needed for cooling the internal combustion
engine (18) or a cooling circuit comprising the internal combustion
engine (18), said fan wheel (1) including a fan wheel hub (4) with
radial fan blades (2) pivotally supported on the hub (4) and
including a control piston (11) axially movably disposed in the hub
(4) and connected to the fan blades (2) for pivoting the fan blades
(2), the fan blades (2) being pivotable over a range including a
switch-over neutral position in which the blades (2) are oriented
in a plane including the axis of rotation of the fan wheel (1), so
that the fan wheel (1) is adjustable to blow in either axial
direction depending on the pivot position of the blades at one or
the other side of the switchover neutral position, a measuring
arrangement (26) for determining the position of the control piston
(11) in the hub (4) and, as a result, the pivot positions of the
blades (2), a fan control unit (51) in communication with the
measuring arrangement for recording the actual pivot position of
the fan blades (2) and comparing it with a desired blade position
which is determined based on engine operating conditions for
providing a desired cooling performance with a certain blade angle
position, the fan control unit (51) providing, upon detecting a
deviation between the actual and the desired pivot position of the
fan blades (2), an input signal for adjusting the fan blade pivot
position.
2. The internal combustion engine according to claim 1, wherein
control valves (54, 55) are provided for controlling the admission
of fluid to the piston (11) in the hub (4) and for the release of
the fluid for adjusting the pivot position of the fan blades (2),
the control signal for adjusting the blade pivot position being
supplied to the respective control valve (54, 55).
3. The internal combustion engine according to claim 1, wherein the
measuring arrangement includes a Hall sensor arrangement (36) with
a magnet (37) disposed on the control piston (11) so as to be
movable with said control piston (11) and said fan wheel hub (4)
and a position sensor (35) stationarily supported adjacent the fan
wheel hub (4) for sensing the speed of the fan wheel (1) and the
position of the piston (11).
4. The internal combustion engine according to claim 1, wherein the
desired cooling performance of the fan wheel (1) is determined
based on the engine speed and various engine operating
conditions.
5. The internal combustion engine according to claim 2, wherein the
desired cooling performance is provided as an input signal with a
signal strength weighted over the performance spectrum and
established in relation to the blade pivot position in one of a
computerized, graphic and performance graph-based manner such that
a minimum signal strength of the input signal corresponds to a
maximum blade angle position for maximum cooling performance
whereby, upon signal failure, the fan blades are in a maximum
cooling performance position.
6. The internal combustion engine according to claim 1, wherein the
input signal is a PWM (Pulse Width Modulated) signal which is in a
relationship with the blade angle position in such a way that a low
PWM value of 0% corresponds to one blade pivot angle end position
and a high value of 100% of the PWM signal corresponds to the
opposite blade pivot angle end position, the blades (2), upon
pivoting from one to the other end position, and vice versa, moving
through their neutral position.
7. The internal combustion engine according to claim 6, wherein the
one or the other blade pivot angle end position corresponds to the
end position of the control piston (11) which it assumes when no
pressurized fluid is applied thereto while the respective other or
one blade pivot angle end position corresponds to the end position
of the control piston (11) when subjected to full pressure.
8. The internal combustion engine according to claim 1, wherein the
respective blade angle is formed by the angle of the blade (2)
established between a plane normal to the axis of rotation of the
fan wheel (1) and the angle of the blades (2) relative thereto.
9. The internal combustion engine according to claim 3, wherein the
Hall sensor arrangement is provided so as to sense the position of
the control piston (11) and the speed of the fan wheel (1).
10. The internal combustion engine according to claim 2, wherein
the control valves (54, 55) are 3/2-way inlet and outlet
valves.
11. The internal combustion engine according to claim 9, wherein
the Hall sensor arrangement (36) includes a speed transmitter for
the fan wheel (1).
12. The internal combustion engine according to claim 11, wherein
the speed of the fan wheel (1) assigned to the respective desired
cooling performance is monitored via the Hall sensor arrangement
(36) acting as speed signal transmitter.
13. A cooling system for an internal combustion engine with a fan
system including a fan wheel (1) having an adjustable cooling
performance and an engine control unit (50) providing control data
for the cooling performance of the fan needed for cooling the
internal combustion engine (18) or a cooling circuit comprising the
internal combustion engine (18), said fan wheel (1) including a fan
wheel hub (4) with radial fan blades (2) pivotally supported on the
hub (4) and including a control piston (11) axially movably
disposed in the hub (4) and connected to the fan blades (2) for
pivoting the fan blades (2), the fan blades (2) being pivotable
between opposite end positions over a range including a neutral
switch-over position in which the blades (2) are oriented in a
plane including the axis of rotation of the fan wheel (1) so that
the fan wheel (1) is adjustable to blow in either axial direction
depending on the pivot position of the blades (2) at one or the
other side of the neutral switch-over position, a measuring
arrangement (26) for determining the position of the control piston
(11) in the hub (4) and, as a result, the pivot positions of the
blades (2), a fan control unit (51) in communication with the
measuring arrangement for recording the actual pivot position of
the fan blades (2) and comparing it with a desired blade position
which is determined based on engine operating conditions for
providing a desired cooling performance with a certain blade angle
position, the fan control unit (51) providing, upon detecting a
deviation between the actual and the desired pivot position of the
fan blades (2), an input signal for adjusting the fan blade pivot
position said fan wheel (1) having a cooling performance which is
variable and adjustable dependent on the respective speed and the
operating conditions of the internal combustion engine under the
control of a control signal determined on the basis of the desired
cooling performance.
14. The cooling system according to claim 13, wherein the
adjustment of the fan wheel (1) to the desired cooling performance
occurs based on a previous setting in a control circuit in which
the respective blade angle is compared to the desired blade angle
and deviations are corrected by controlling the inlet and outlet
valves (54, 55) wherein an examination of the correction of the
setting of the blade angle to the desired blade angle is used as a
functional examination of the inlet and outlet valves (54, 55).
15. The cooling system according to claim 14, wherein the control
circuit ends in an actual position--desired position comparison for
the blade angle wherein, with values deviating from the desired
blade angle, a new pass through the control circuit is initiated
and wherein for the comparison an overall time limit is
predetermined, which, when exceeded, results in a system error
indication.
16. The cooling system according to claim 15, wherein, in
accordance with the predetermined overall time for the passage of
the control circuit and the--within the given overall
time--relatively small displacement travel of the control piston
(11), a fixed response time is provided for the inlet and outlet
valves (54, 55) which is a fraction of the overall time.
17. The cooling system according to claim 13, wherein the control
circuit (51) is part of a control arrangement (50) for which, at an
input, a signal value for the desired cooling performance or,
respectively, the desired blade position, in particular a PWM
signal value, is determined and a transition to the control circuit
within a given overall time occurs only if the signal exceeds a
predetermined minimum value.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to an internal combustion engine with
a fan system including a fan wheel with adjustable fan
performance.
[0002] Such adjustable fan systems are known in the art,
particularly in a form wherein the fan wheel is operated in a
temperature-dependent manner for example via a viscous clutch or
another way in which the fan speed is adjustable relative to the
speed of the internal combustion engine driving the fan. Also,
solutions are known wherein a separate drive is provided for the
fan wheel, for example an electric motor whose speed can be
controlled independently of the speed of the internal combustion
engine.
[0003] Other air moving systems, which include a fan wheel which is
adjustable for controlling the fan performance and wherein for
changing the performance not only the fan speed is adjustable but
also fan blades are provided which are angularly adjustable in an
active or passive manner. The adjustability of the fan blades with
active admission of air to the fan blades is in connection with air
movers, as they are known for example from EP 0 945 676 A2, not
limited to a change of the blade angle while maintaining the moving
direction of the air but also the direction of moving the air may
be reversible. If, in the process the fan blades are turned beyond
a direction transverse to the direction of rotation, a reverse flow
can be generated with small changes of the annular positions of the
fan blades about the pivot axis normal to the direction of rotation
of the fan wheel.
[0004] It is desirable to control the fan wheels of this type in
particular with regard to the setting of the blade angles depending
on the desired cooling performance in such a way that an
instantaneous adaptation of the blade angles to the desired cooling
performance is achieved. On the other hand, the respective blade
angle corresponding to the desired cooling performance should be
obtained as accurately as possible and with little control
requirements using, in particular, control data already available
in the engine control system and also high operational safety
should be maintained.
SUMMARY OF THE INVENTION
[0005] In an internal combustion engine cooling system, wherein a
fan with an adjustable cooling performance is provided with a fan
wheel having a hub with radial fan blades pivotally supported on
the hub, a control piston is disposed in the hub and connected to
the blades for the pivot position adjustment thereof over a range
from a suction position to a blowing position under the control of
a control unit causing movement of the piston for pivoting the
blades to a position for a cooling performance adjusted to the
engine requirements. The system is simple, safe and efficient and
permits counter flow operation of the fan for cleaning
purposes.
[0006] For an accurate adjustment of the pivot angle of the blades
to obtain the desired cooling performance, the control movement of
the control piston for adjusting the respective blade angles is
needed. The actual determination of the axial position of the
control piston in the hub in accordance with a momentary blade
angle adjustment is determined in accordance with the invention via
a measuring arrangement assigned to the fan wheel hub. As such a
measuring arrangement a Hall sensor is particularly suitable,
specifically a Hall sensor arrangement with a magnet arranged on
the control piston and a sensor arranged preferably fixed outside
the fan wheel hub. It is particularly advantageous and
cost-effective if the sensor arrangement is provided on the
non-rotating part of the supply structure for the fluid admitted to
the control piston which extends into the fan wheel hub. In this
way, for the magnet as well as the sensor mounting means are
provided which are not critical as far as space considerations are
concerned and which can be realized by simple means possibly even
by cementing.
[0007] With the possibility to exactly determine the respective
position of the control position, the blade angle position which
corresponds directly to the position of the control piston and also
the rotational speed of the fan wheel which is driven by the engine
via the control unit of the internal combustion engine, the fan
performance can be accurately tuned to the desired cooling
performance. This can be achieved under the control of a
performance graph or with some computer operation via a control
unit in which the operational data of the internal combustion
engine are available which are needed to determine the desired
cooling performance. They are combined with the data defining a
position value of the control piston corresponding to the
respective momentary blade angle position. In this way from these
values the position of the control piston and consequently the
blade angle setting can be directly adapted to the desired cooling
performance by a corresponding fluid admission to the control
piston.
[0008] With respect to the transmission of the digital control data
which are available to the engine control unit and the generally
analog control of the control valves it has been found expedient if
the data to be transmitted from the engine control unit to the fan
control unit are transmitted in the form of a PWM (Pulse Width
Modulated) signal which is representative of the desired cooling
performance and which facilitates a direct assignment to the
respective blade angle to be set in a simple manner via the value
thereof. The assignment is expediently so selected that the minimum
value of 0% corresponds to the maximum blade angle and the maximum
value corresponds to the minimum blade angle. In accordance with
the invention, the data are transmitted via a CAN bus system which
is generally already present.
[0009] In connection with the present invention, of the whole
adjustment range for the blade angle, that is, the adjustment range
between its end position for suction and its end position for
blowing, only a part range is utilized for the operation of the
blades during adjustment to the desired cooling performance of the
fan. This partial range extends for a fan wheel whose blades are
adjusted between suction and blowing operation or vice versa across
a transverse orientation relative to the direction of rotation of
the fan wheel, only over a section which is disposed between an end
position of the control piston and a position corresponding to the
operating position in which the flow generated by the blades is
reversed. In particular with blades which can be pivoted beyond a
position of the blades transverse to the direction of rotation of
the fan the overall adjustment range can be kept relatively small.
The adjustment range used for the setting of the blade angle to
achieve the desired cooling performance is about 40 to 50.degree..
The blade angle is about 10 to 20.degree. for minimum cooling
requirements and 40-50.degree. for maximum cooling
requirements.
[0010] Consequently, only a part of the range over which the blade
angle is adjustable in accordance with the control path length of
the control position is used for a sufficiently accurate adjustment
of the blade angle by means of a corresponding sufficiently
accurate control of the control piston by means of the control
valves. For the control valves the opening times and the closing
times can be predetermined based on a respective control impulse,
but the time periods may also be adjustable. This can be done in
particular in connection with a throttling effect in order to
achieve a uniform and smooth position adjustment with a view to
minimizing wear and also avoiding the generation of vibrations.
[0011] With Hall sensors for determining the position of the
control piston, also the speed of the fan wheel can be determined
without incurring additional expenses. Although the speed of the
fan wheel is determined via the engine control unit for providing a
desired cooling performance and is taken into consideration in the
information supplied to the control unit, the determination of the
speed via the fan wheel by the Hall sensors with corresponding
information supplied to the engine control unit has been found
expedient since in this way it can be determined directly whether
the fan wheel is in fact driven as expected and at a speed
corresponding to the speed of the internal combustion engine.
[0012] The invention further resides in a cooling system for an
internal combustion engine with a fan wheel whose speed is
controlled depending on the level of the desired cooling
performance as determined to be necessary for the internal
combustion engine with regard to the engine speed and operating
condition. This control is preferably dependent on a respective
previous setting in a control circuit in which the respective
momentary blade angle is adapted to the desired blade angle and
deviations are corrected by controlling the control fluid inlet or
outlet valves. An examination of the correction of the setting of
the blade angle to the desired blade angle may also be used as a
functional examination of the inlet and the outlet valve or at
least the valve block comprising the inlet and outlet valve.
[0013] The control circuit operates with an actual position and
desired position comparison for the blade angle. When the
comparison shows a value which differs from the desired value for
the vane angle another pass of the control circuit is initiated.
For the duration of the control procedure a time limit is provided
and a system error is determined if the time limit is exceeded.
[0014] The time limit is preferably in the range of about 10 to 30
sec, in particular at values where deviations from the desired
cooling performance are not critical. Consideration is also given
to the predetermined opening and closing times of the control
valves which are a fraction of the time limit, that is about 15
milliseconds, if the time limit is for example 15 sec.
[0015] In connection with such tuned time periods, there are
sufficient rest periods in which the system of pressure driven
and/or spring-supported control piston and fan blades held at the
respective blade angles are stabilized even with sudden jerk-like
adjustment steps, so that a sufficiently accurate determination of
the respective actual blade angle is possible. The determination of
the blade angle in comparison with the desired blade angle may also
be used for a determination of a proper functioning of the control
valves.
[0016] The invention will become more readily apparent from the
following description of a particular embodiment thereof with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic partial representation of a fan
wheel,
[0018] FIG. 2 shows an arrangement of a fan wheel in a position
between a piston internal combustion engine used as a drive motor
and a cooler wherein, by changing the blade angle of the fan wheel,
the cooler performance is adjustable and the air flow direction of
the fan is reversible for operation of the fan selectively in
blower or suction direction,
[0019] FIGS. 3-5 show the fan wheel schematically with different
blade angle settings,
[0020] FIG. 6 shows a characteristic performance graph for the
relation of the blade angle with respect to a PWM signal
corresponding to a desired cooling performance of the internal
combustion engine, and
[0021] FIG. 7 shows schematically the fan wheel and the control
arrangement provided for controlling the blade angle of the fan
blades.
DESCRIPTION OF A PARTICULAR EMBODIMENT
[0022] FIG. 1 shows a part of a fan wheel 1 in a schematic
sectional view. The axis of rotation of the fan wheel 1 is
indicated by the reference numeral 10. Concentrically with the axis
of rotation 10 the wheel 4 is arranged with its pot-shaped hub body
5, which has a bottom wall 6, a hub wall 7 and a cover 8 covering
the inner space 9 of the hub. In the hub wall 7, the foot sections
3 of the fan blades 2 are supported so as to be rotatable about
pivot axes 23 disposed in a plane extending normal to the axis of
rotation 10 of the hub 4. In the inner space 9 of the hub body 5
which is closed by the cover 8 a control piston 11 is disposed so
as to be axially movable in the direction of the axis of rotation
10. The piston 11 has a piston bottom 13 arranged opposite the
cover and having a piston wall 12 extending parallel, and adjacent
to, the hub wall 7. An annular gap between the piston wall 12 and
the hub wall 7 is sealingly bridged so that an operating chamber 16
is formed between the piston bottom 13 and the cover 8. A supply
line 14 extends to the operating chamber 16 via a rotational
penetration 17 which is concentric with the pivot axis 10. Opposite
the operating chamber 16, to which an operating fluid can be
admitted, the operating piston 11 is elastically supported on the
bottom wall 6 by means of compression springs 20, which, as shown
in FIG. 1, are disposed in spring pockets 19 formed in the
operating piston 11. Several such spring pockets 19 are provided
over the circumference of the operating piston 11. The operating
piston 11 however may be supported by other axial support elements
which are spring-like.
[0023] The fan blades 2, which are pivotable about their respective
axes of rotation 23, are rotatably supported by their respective
foot sections 3 and bearings 21 mounted in the hub wall 7. Axial
support is provided by means of a support plate 22 onto which the
respective foot section 3 is mounted and which is provided,
eccentrically with respect to the axis of rotation 23, with an
actuating pin 24 projecting into a recess 25 in the wall 7 the
control piston. The recess 25 may be in the form of a dead end bore
or an annular groove.
[0024] With the eccentricity of the actuating pin 24 relative to
the pivot axes 23 of the respective fan blades 2, an axial
displacement of the control piston in the direction of the axis of
rotation 10 of the fan wheel 1 results in a rotation of the fan
blades 2 about their respective pivot axes 23.
[0025] The axial displacement of the piston is achieved by
admitting an operating fluid under pressure, in particular
pressurized air to the operating chamber 16. The pressurized air is
supplied to, and/or released from, the operating chamber 16 via the
rotational penetration 17 preferably through a supply line 14
including control valves 54, 55 or similar. FIG. 1 further
indicates the presence of a measuring arrangement 26 for detecting
the axial position of the control piston 11 and consequently,
indirectly also of the pivot position of the fan blades 2 relative
to the pivot axis 23. As a result, the angular position 33 of the
blades can be detected. The control piston 11 is biased by the
operating fluid in one direction against the force of a spring
support, for example, coil springs 20 by which the piston 11 is
movable in the opposite direction. FIG. 2 shows, in a highly
schematic way, the arrangement of such a fan wheel between an
internal combustion engine 18 and a cooler 27 disposed in front of
the internal combustion engine 18. Depending on the pivot position
of the fan blades 2 with respect to the pivot axis 23, the fan
wheel 1 operates with a suction mode according to arrow 28 moving
air toward the internal combustion engine 18 or in a blowing mode,
that is, moving air in the direction of the arrow 29 toward the
cooler 27 in order to blow deposits or debris or dust off the
cooler 27. The direction of rotation of the fan wheel 1 is the same
in both modes of operation that is during suction operation (arrow
28) and blowing operation (arrow 29) and is indicated by the arrow
30 so that in a radial view as, the fan wheel and the fan wheel
blades move in a direction as indicated by the arrow 31 with the
hub 4 appearing as shown in FIG. 2.
[0026] A fan blade position for suction operation (arrow 28) is
shown in FIG. 2 for a fan blade 32 extending in the direction
normal to the drawing plane. The respective blade angle is
indicated by the numeral 33 and opens with respect to the shown
angular position of the fan blade 2 opposite to the direction of
rotation 31. The fan performance is determined by the size of the
blade angle 33 based on the speed of the fan wheel 1. The
performance during suction operation (arrow 28) increases with
increasing fan blade angle 33. The switchover of the fan blade from
suction operation to blowing operation occurs in accordance with
the arrow 34 via a trans-verse orientation with respect to the
direction of rotation 31 and occurs suddenly once the transverse
position has been reached.
[0027] This is shown also in FIGS. 3-5, wherein essentially the
same reference numerals are used. The FIGS. 3 and 4 concern the
blade angle-controlled suction operation with regard to the cooling
performance demand of the internal combustion engine wherein the
respective blade angle is adjusted by the control piston 11 in
accordance with the desired cooling performance. Herein the fan
performance is tuned to the cooling performance so that a cooling
operation with optimal efficiency is achieved, that is with minimal
power requirements of the internal combustion engine for the
cooling.
[0028] FIG. 5 shows the blade position during blowing operation.
This position is reached when the fan blade 32 in accordance with
FIG. 2 is pivoted beyond the transverse position with respect to
the circumferential direction in accordance with the arrow 34. In
this range, the blade angle is also dependent on the respective
position of the control piston 11 but the position of the control
piston 11 is not controlled by applying pressure fluid to the
piston operating chamber 16 depending on the desired cooling
performance. Rather the control piston 11 is moved to an end
position that is the end pivot position of the fan blades for
blow-cleaning the radiator.
[0029] The data needed for the setting of the fan performance
corresponding to the cooling performance required by the internal
combustion engine 18 are generally present in the engine control
unit 50. FIG. 6 shows for a fan wheel operating at a speed
corresponding to that of the internal combustion engine 18 a
control for the setting of the fan blade angle 33 for the fan
blades 2, 32 corresponding to the engine requirements.
[0030] At times the control data corresponding to the cooling
performance demand are already processed in such a way that they
are available as signal of a signal strength corresponding to the
desired cooling performance. This applies in particular to
solutions where a fan wheel is controlled by a viscous clutch by
which the speed of the fan wheel is controlled depending on
strength of the control signal. In this solution for example a PWM
signal of a signal strength corresponding to the desired cooling
performance is supplied to the control unit 51, by which the
pressure application to the control piston 11 for the setting of
the fan blade angle position for obtaining the desired cooling
performance is controlled taking into consideration that the speed
of the fan wheel 1 is at a certain predetermined, in particular
fixed, ratio to the speed of the internal combustion engine.
[0031] In such an arrangement, the speed of the fan wheel 1 may for
example be the same as the speed of the internal combustion engine
with a corresponding drive connection to the crankshaft of the
internal combustion engine. If a particular transmission is
interposed, for example, a belt drive, another but still fixed,
speed ratio may be provided.
[0032] Of the fan blade angle range 53 basically usable for the
setting of the cooling performance--as shown in FIG. 3--that is, in
the range from a blade position transverse to the axis of rotation
10 of the fan wheel 1 in which the blades 2, 32 are oriented in the
direction of rotation 31 of the fan wheel to a direction of a plane
which includes axis of rotation 10, only a part range of the
adjustability of the blades is used for controlling the fan to
generate the cooling performance required by the internal
combustion engine. This part range which is apparent from the
schematic representation of FIGS. 3 and 4 extends in the exemplary
representations of FIGS. 3 and 4 between a blade angle of
13.degree. and a blade angle of 45.degree. wherein the cooling
performance increases with increasing blade angle. Herein the
larger blade angle which corresponds to the larger fan performance
represents the maximum needed cooling performance and, vice-versa,
the smaller blade angle corresponds to the lowest needed cooling
performance.
[0033] In accordance with this relationship, the PWM (Pulse Width
Modulated) signal 52 is supplied to control unit 51 and, as shown
for example in the performance graph of FIG. 6, depending on the
strength of the PMW signal 52, a particular blade angle (FW) is
predetermined. In FIG. 6, the blade angle is provided in relation
to the PWM signal strength on a % basis. 100% corresponds to the
smallest blade angle of the used blade angle range and consequently
the smallest cooling performance according to a minimum cooling
performance required by the internal combustion engine 18. Vice
versa, a signal strength of 0% corresponds to the maximum blade
angle of the blade angle range used and consequently, the maximum
fan performance in accordance with a maximum cooling performance
needed by the internal combustion engine.
[0034] Herein the control unit 51 controls the control valves 54,
55 by which fluid, in particular air, is admitted to the control
piston 11 in accordance with the opening and closing times of the
control valves. Here, the control valve 54 is the inlet valve and
the control valve 55 is the outlet valve. The control lines
assigned to the control valves are designated by the reference
numerals 56 and 57. Starting with the control valves, fluid is
supplied to the operating chamber 16 via the rotational penetration
17, see FIG. 1, where, as part of the measuring arrangement 26, the
sensor 35 of a Hall sensor arrangement 36 is arranged. The sensor
arrangement includes a magnet 37 which is disposed on the bottom
wall 13 of the control piston 11 or is integrated into piston 11,
for example disposed in a pocket thereof.
[0035] FIG. 7 shows further that the measuring arrangement 26 in
particular in the form of a Hall sensor arrangement 36 detects the
position of the control piston 11 and consequently the angular
pivot position of the fan blades and provides a corresponding
confirmation signal 58 to the control unit 51 which then supplies a
confirmation signal back to the engine control unit.
[0036] FIG. 7 also shows that the measuring arrangement 26
particularly in the form of a Hall sensor arrangement 36 also
detects the rotational speed of the fan wheel 1 which information
may also be supplied to the control unit 51 as indicated by the
line 60. By comparison of the speed of the fan wheel 1 determined
in this way with the fan speed as determined by the engine control
unit 50 on the basis of the engine speed, it can be examined
whether the parameters processed by the engine control unit 50 and
used for the PWM signal supplied to the control unit 51 concerning
the blade angle have resulted in a corresponding result.
Discrepancies between the speed of the fan wheel 1 as determined by
the engine control unit 50 and the speed signal supplied via the
line 60 as confirmation signal permit an examination of the signal
chain including the control valves 54, 55 disposed in the signal
chain. As a result, the measuring arrangement 26, particularly in
its form as a Hall sensing arrangement 36, makes a functional
examination with regard to a consistency of the desired cooling
performance on one hand and the corresponding fan performance on
the other hand possible without any additional expenditure.
[0037] Based on such an arrangement of an internal combustion
engine 18 with a fan system which includes a fan wheel 1 with
adjustable blades 2 and a cooling system for an internal combustion
engine with a fan wheel assigned to the fan system of the internal
combustion engine, a control arrangement would be expedient based
on the value of the PWM signal supplied by the engine control unit
50 to the control unit 51 which signal corresponds to the desired
cooling performance and the corresponding fan performance. If this
condition and, consequently, a sufficiently accurate determination
of the blade angle are fulfilled, a total time available for
passing a control circuit path is provided. If this is not
acknowledged by an actualized return signal received by the engine
control unit, a new control pass with determination of the PWM
signal value is initiated. The time generally available for passing
the control circuit begins, after the conversion of the PWM signal
to the respective blade angle, with a comparison of the blade angle
as desired blade angle with the actual blade angle. If deviations
are found, depending on the determination whether the actual blade
angle is too large or too small, the release valve or the supply
valve is energized for adjusting the control piston 11.
[0038] Preferably, fixed opening and closing times are provided for
the respective control valves. It may however also be expedient to
operate with opening and closing times which depend in each case on
the size of the desired adjustment of the blade angle. This is true
particularly for the control of the control valves for operating
ranges which are outside the range in which the fan performance is
controlled dependent on the desired cooling performance, which is
also determined by the desired cooling performance, by changing the
blade angle position.
[0039] The blade angle set during a control procedure by operation
of the control valves 54, 55 is used in the control unit as an
actualized return signal for an actualized PWM signal. Preferably,
the blade angle is again detected following a pause. This forms the
basis for a further actual position-desired position comparison of
the blade angle based on which, in the case of differences, a new
pass through the control circuit is initiated.
[0040] Changes in the blade angle with respect to the setting
thereof before the initiation of a possibly necessary correction by
a control of the control valves in comparison with the setting
after the correction by the control of the valves are used in the
control circuit as signals for an examination whether the control
valves combined in a valve block have worked in accordance with the
provided values or whether errors have occurred in the operation of
the control valves and/or in the control valves themselves wherein
the predetermined waiting time facilitates also a determination of
possible leakages by improperly closing valves.
[0041] The invention is, in particular in connection with such a
control, of particularly simple design which satisfies also high
safety requirements. Engine damages as a result of failure of the
cooling system or malfunctioning of the cooling system can be
avoided. The system operates with high efficiency and offers the
possibility to be used in a suction mode as well as in a blowing
mode for the removal of deposits or dust from the radiator.
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