U.S. patent application number 16/330018 was filed with the patent office on 2019-07-04 for a method for controlling the temperature of a cooling fluid in a cooling system and a cooling system.
This patent application is currently assigned to SCANIA CV AB. The applicant listed for this patent is SCANIA CV AB. Invention is credited to Erik HOCKERDAL, Bjorn JOHANSSON.
Application Number | 20190204022 16/330018 |
Document ID | / |
Family ID | 61562792 |
Filed Date | 2019-07-04 |
United States Patent
Application |
20190204022 |
Kind Code |
A1 |
JOHANSSON; Bjorn ; et
al. |
July 4, 2019 |
A METHOD FOR CONTROLLING THE TEMPERATURE OF A COOLING FLUID IN A
COOLING SYSTEM AND A COOLING SYSTEM
Abstract
Provided is a method for controlling the temperature of a
cooling fluid in a cooling system comprising a cooling circuit
connected to a condenser of a waste heat recovery system, a cooling
pump arranged to circulate a cooling fluid through the cooling
circuit and a radiator arranged for cooling the cooling fluid, a
bypass circuit, a first and a second valve unit, wherein the first
valve unit is arranged to control the flow of cooling fluid through
the radiator and the bypass circuit, and the second valve unit
controls the flow of cooling fluid passing through the condenser. A
condenser-in temperature of the cooling fluid is determined by a
first temperature sensor and an engine-in temperature of the
cooling fluid is determined by a second temperature sensor. The
flow of the cooling fluid is controlled by the first valve unit
and/or the second valve unit based on the determined condenser-in
and engine-in fluid temperatures.
Inventors: |
JOHANSSON; Bjorn; (Alvsjo,
SE) ; HOCKERDAL; Erik; (Sodertalje, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCANIA CV AB |
Sodertalje |
|
SE |
|
|
Assignee: |
SCANIA CV AB
Sodertalje
SE
|
Family ID: |
61562792 |
Appl. No.: |
16/330018 |
Filed: |
August 22, 2017 |
PCT Filed: |
August 22, 2017 |
PCT NO: |
PCT/SE2017/050837 |
371 Date: |
March 1, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02G 5/02 20130101; F16T
1/00 20130101; F01K 9/00 20130101; F01P 3/20 20130101; F02G 5/04
20130101; F01K 23/06 20130101; Y02T 10/12 20130101; F01N 5/02
20130101; F01P 3/12 20130101; F28D 21/0003 20130101; Y02T 10/166
20130101; F28D 2021/0094 20130101; F01P 7/14 20130101; F28F 2250/06
20130101; F28F 27/02 20130101 |
International
Class: |
F28D 21/00 20060101
F28D021/00; F28F 27/02 20060101 F28F027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2016 |
SE |
1651213-9 |
Claims
1. A method for controlling the temperature of a cooling fluid in a
cooling system arranged in fluid connection with an internal
combustion engine of a vehicle, the cooling system comprising a
cooling circuit connected to a condenser of a waste heat recovery
system, a cooling pump arranged to circulate a cooling fluid
through the cooling circuit and a radiator arranged for cooling the
cooling fluid, a bypass circuit, a first valve unit and a second
valve unit, wherein the first valve unit is arranged to control the
flow of cooling fluid through the radiator and the bypass circuit
respectively, and the second valve unit is arranged to control the
flow of cooling fluid passing through the condenser, wherein said
method comprises: determining a condenser-in cooling fluid
temperature by means of a first temperature sensor arranged
upstream of the condenser and downstream of a first mixing point,
where the cooling fluid from the radiator and bypass circuit are
mixed, and an engine-in cooling fluid temperature by means of a
second temperature sensor arranged upstream of the internal
combustion engine and downstream of a second mixing point, where
the cooling fluid from the condenser and bypass circuit are mixed;
and controlling the flow of the cooling fluid in the cooling system
by means of the first valve unit and/or the second valve unit based
on the determined condenser-in and engine-in fluid
temperatures.
2. The method according to claim 1, wherein the controlling step
comprises comparing the determined cooling fluid temperatures with
pre-defined reference cooling fluid temperatures.
3. The method according to claim 2, wherein the controlling step
comprises increasing the flow of cooling fluid through the radiator
by means of the first valve unit if the engine-in cooling fluid
temperature is higher than the predefined engine-in cooling fluid
temperature.
4. The method according to claim 2, wherein the controlling step
comprises decreasing the flow of cooling fluid from the bypass
circuit via a second return pipe to the first mixing point by means
of the second valve unit, if the condenser-in cooling fluid
temperature is higher than the pre-defined condenser-in cooling
fluid temperature, or by increasing the flow of cooling fluid from
the bypass circuit via a second return pipe to the first mixing
point by means of the second valve unit, if the condenser-in
cooling fluid temperature is lower than the pre-defined
condenser-in cooling fluid temperature.
5. The method according to claim 1, wherein the controlling step
comprises arranging the second valve unit to adapt to a position of
the first valve unit to thereby control the condenser-in and/or the
engine-in fluid temperature.
6. The method according to claim 1, wherein the determining step
further comprises determining at least one further cooling fluid
temperature which is selected from an engine-out, a radiator-out or
a condenser-out cooling fluid temperature, or a condenser-in or a
condenser-out working fluid temperature, the fluid temperatures
being determined by means of a respective third temperature sensor,
fourth temperature sensor, fifth temperature sensor, sixth
temperature sensor and/or seventh temperature sensor.
7. The method according to claim 6, wherein the controlling step
comprises lowering the pre-defined condenser-in and engine-in
cooling fluid temperatures, if at least one of the engine-out,
radiator-out or condenser-out cooling fluid temperatures or the
condenser-in or condenser-out working fluid temperatures exceeds a
predefined value for the engine-out, a radiator-out or a
condenser-out cooling fluid temperature.
8. The method according to claim 1, wherein the controlling step
further comprises predicting coming driving conditions by means of
look-ahead active prediction function and controlling the
condenser-in and the engine-in cooling fluid temperatures further
based on the predicted coming driving conditions.
9. A cooling system associated with an internal combustion engine
of a vehicle, the cooling system comprising: a cooling circuit
connected to a condenser of a waste heat recovery system; a cooling
pump arranged to circulate a cooling fluid through the cooling
circuit; a radiator arranged for cooling the cooling fluid; a
bypass circuit; a first valve unit and a second valve unit, wherein
the first valve unit is arranged to control the flow of cooling
fluid CF through the radiator and the bypass circuit respectively,
and the second valve unit is arranged to control the flow of
cooling fluid passing through the condenser of the waste heat
recovery system; a first temperature sensor arranged upstream of
the condenser and downstream of a first mixing point, where the
cooling fluid from the radiator and bypass circuit are mixed; a
second temperature sensor arranged upstream of the internal
combustion engine and downstream of a second mixing point, where
the cooling fluid from the condenser and bypass circuit are mixed;
and a control unit adapted to control the first valve unit and the
second valve unit so that the flow of the cooling fluid in the
cooling system is controlled based on temperature values determined
by the first and second temperature sensors.
10. The cooling system according to claim 9, wherein the cooling
circuit comprises at least one additional temperature sensor
selected from a third temperature sensor arranged between the
internal combustion engine and the first valve unit, a fourth
temperature sensor arranged between the radiator and the first
mixing point, a fifth temperature sensor arranged between the
condenser and the second mixing point, a sixth temperature sensor
arranged in the waste heat recovery system upstream of the
condenser to measure the condenser-in temperature of the working
fluid, or a seventh temperature sensor arranged in the waste heat
recovery system downstream of the condenser to measure the
condenser-out temperature of the working fluid, wherein the at
least one additional temperature sensor is connected to the control
unit.
11. The cooling system according to claim 9, wherein the control
unit is adapted to control the engine-in temperature of the cooling
fluid in the cooling circuit by means of the first valve unit to
increase the flow of cooling fluid through the radiator and/or to
reduce the flow of cooling fluid passing through the bypass circuit
by means of the second valve unit.
12. The cooling system according to claim 9, wherein the cooling
circuit is arranged with one cooling pump to circulate the cooling
fluid through the cooling circuit.
13. A system associated with an internal combustion engine of a
vehicle, said system comprising: a cooling system comprising: a
cooling circuit connected to a condenser of a waste heat recovery
system; a cooling pump arranged to circulate a cooling fluid
through the cooling circuit; a radiator arranged for cooling the
cooling fluid; a bypass circuit; a first valve unit and a second
valve unit, wherein the first valve unit is arranged to control the
flow of cooling fluid CF through the radiator and the bypass
circuit respectively, and the second valve unit is arranged to
control the flow of cooling fluid passing through the condenser of
the waste heat recovery system; a first temperature sensor arranged
upstream of the condenser and downstream of a first mixing point,
where the cooling fluid from the radiator and bypass circuit are
mixed; a second temperature sensor arranged upstream of the
internal combustion engine and downstream of a second mixing point,
where the cooling fluid from the condenser and bypass circuit are
mixed; and a control unit adapted to control the first valve unit
and the second valve unit so that the flow of the cooling fluid in
the cooling system is controlled based on temperature values
determined by the first and second temperature sensors; a waste
heat recovery system; and a condenser connecting the cooling system
and the waste heat recovery system.
14. A vehicle comprising a cooling system, which, in turn,
comprises: a cooling circuit connected to a condenser of a waste
heat recovery system; a cooling pump arranged to circulate a
cooling fluid through the cooling circuit; a radiator arranged for
cooling the cooling fluid; a bypass circuit; a first valve unit and
a second valve unit, wherein the first valve unit is arranged to
control the flow of cooling fluid CF through the radiator and the
bypass circuit respectively, and the second valve unit is arranged
to control the flow of cooling fluid passing through the condenser
of the waste heat recovery system; a first temperature sensor
arranged upstream of the condenser and downstream of a first mixing
point, where the cooling fluid from the radiator and bypass circuit
are mixed; a second temperature sensor arranged upstream of the
internal combustion engine and downstream of a second mixing point,
where the cooling fluid from the condenser and bypass circuit are
mixed; and a control unit adapted to control the first valve unit
and the second valve unit so that the flow of the cooling fluid in
the cooling system is controlled based on temperature values
determined by the first and second temperature sensors; a waste
heat recovery system.
15. (canceled)
16. A computer program product comprising a program code stored on
a non-transitory computer-readable medium for controlling the
temperature of a cooling fluid in a cooling system arranged in
fluid connection with an internal combustion engine of a vehicle,
the cooling system comprising a cooling circuit connected to a
condenser of a waste heat recovery system, a cooling pump arranged
to circulate a cooling fluid through the cooling circuit and a
radiator arranged for cooling the cooling fluid, a bypass circuit,
a first valve unit and a second valve unit, wherein the first valve
unit is arranged to control the flow of cooling fluid through the
radiator and the bypass circuit respectively, and the second valve
unit is arranged to control the flow of cooling fluid passing
through the condenser, said computer program product comprising
computer instructions to cause one or more electronic control units
or computers to perform the following operations: determining a
condenser-in cooling fluid temperature by means of a first
temperature sensor arranged upstream of the condenser and
downstream of a first mixing point, where the cooling fluid from
the radiator and bypass circuit are mixed, and an engine-in cooling
fluid temperature by means of a second temperature sensor arranged
upstream of the internal combustion engine and downstream of a
second mixing point, where the cooling fluid from the condenser and
bypass circuit are mixed; and controlling the flow of the cooling
fluid in the cooling system by means of the first valve unit and/or
the second valve unit based on the determined condenser-in and
engine-in fluid temperatures.
17. The method according to claim 3, wherein the controlling step
comprises decreasing the flow of cooling fluid from the bypass
circuit via a second return pipe to the first mixing point by means
of the second valve unit, if the condenser-in cooling fluid
temperature is higher than the pre-defined condenser-in cooling
fluid temperature, or by increasing the flow of cooling fluid from
the bypass circuit via a second return pipe to the first mixing
point by means of the second valve unit, if the condenser-in
cooling fluid temperature is lower than the pre-defined
condenser-in cooling fluid temperature.
18. The cooling system according to claim 10, wherein the control
unit is adapted to control the engine-in temperature of the cooling
fluid in the cooling circuit by means of the first valve unit to
increase the flow of cooling fluid through the radiator and/or to
reduce the flow of cooling fluid passing through the bypass circuit
by means of the second valve unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a national stage application (filed
under 35 .sctn. U.S.C. 371) of PCT/SE2017/050837, filed Aug. 22,
2017 of the same title, which, in turn, claims priority to Swedish
Application No. 1651213-9, both filed Sep. 9, 2016 of the same
title; the contents of each of which are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for controlling
the temperature of a cooling fluid in a cooling system coupled with
an internal combustion engine of a vehicle, a cooling system, a
vehicle comprising such a cooling system, a computer program and a
computer program product according to the appended claims.
BACKGROUND OF THE INVENTION
[0003] Vehicle manufacturers are today striving to increase engine
efficiency and reduce fuel consumption. This is specifically an
issue for manufacturers of heavy vehicles, such as trucks and
buses. One way of improving engine efficiency and fuel consumption
is waste heat recovery. In vehicles with internal combustion
engines some of the energy from the fuel is dissipated as heat
through the exhaust pipes and the engine cooling system. By the use
of a waste heat recovery system the heat from the exhaust gases may
instead be used for example to heat various vehicle components or
to produce mechanical work or electricity. Such mechanical work may
for example be transferred to the driveline and thus be used to
propel the vehicle.
[0004] A waste heat recovery system typically comprises at least
one heat exchanger which transfers heat between a heat source, such
as exhaust gases, and a working fluid. The heat transfer between
the heat source and the working fluid is an exchange of energy
resulting in a change in temperature. A waste heat recovery system
may also be based on a Rankine cycle and thus comprise a working
fluid, a pump for circulating the working fluid in a circuit, at
least one evaporator (heat exchanger), an expansion device and a
condenser. The condenser is typically connected to a cooling
system, which may be part of the engine cooling system. The working
fluid in such waste heat recovery system is suitably in a liquid
state to start with. The pump pressurizes the working fluid which
is pumped through the evaporator. The working fluid is heated by
for example exhaust gases led through the evaporator and the
working fluid thereby evaporates. The vapor may subsequently be
expanded in the expansion device. By means of the expansion device
the recovered heat may thereby be converted into mechanical work.
The vapor is thereafter cooled in the condenser, such that the
working fluid is brought back to its initial liquid state.
[0005] The operating temperature of a cooling fluid in the cooling
system needs to be controlled so that the temperature will not
become too high. If the cooling liquid temperature becomes too high
there is a risk that the condenser or other components of the
cooling system will be damaged. It is therefore important that the
temperature of the cooling fluid in the cooling system can be
controlled.
[0006] Document US2016053666 describes a cooling circuit including
an internal combustion engine, a coolant cooler, a first
thermostat, a first pump, a condenser, a second thermostat and a
second pump, wherein a cooling agent can flow through the cooling
circuit. The combustion engine, first pump, coolant cooler and
first thermostat are arranged in a first circuit, and the
condenser, second thermostat and second pump are arranged in a
second circuit, and wherein the first circuit and second circuit
are in fluid communication with one another in at least two points.
The coolant transition between a coolant inlet and a coolant outlet
of a thermostat can be influenced by an adjustor, which may be
formed of temperature sensitive-elements. Depending on the position
of the adjustor, the coolant can be allowed to flow from a coolant
inlet directly to the coolant outlet of the thermostat.
Alternatively, a mixing position which enables a simultaneous flow
of coolant from both coolant inlets to the coolant outlet can be
attained. However, sufficiently accurate and on the other hand
flexible control of the cooling system cannot be obtained by means
of thermostats. Also, there is a need to simplify and improve the
existing cooling systems connected to waste heat recovery
systems.
SUMMARY OF THE INVENTION
[0007] Despite known solutions in the field, there is still a need
to develop a method for controlling the temperature of a cooling
fluid in a cooling system coupled or associated with an internal
combustion engine of a vehicle, which optimizes engine efficiency,
fuel consumption and which control system is robust.
[0008] An objective of the present invention is to provide an
advantageous method for controlling the cooling fluid temperature
in a cooling system, which optimizes engine efficiency and fuel
consumption.
[0009] Another objective of the invention is to provide a method
for controlling the temperature of a cooling fluid in a cooling
system, which can quickly actuate valves in the system and thus
quickly optimize the cooling fluid temperature.
[0010] A further objective of the invention is to provide a robust
cooling system with reduced risk for operational disturbances.
[0011] The herein mentioned objectives are achieved by a method for
controlling the temperature of a cooling fluid in a cooling system,
a cooling system, a vehicle, a computer program and a computer
program product according to the independent claims.
[0012] Accordingly, the present invention relates to a method for
controlling the temperature of a cooling fluid in a cooling system
arranged in fluid connection with an internal combustion engine of
a vehicle, the cooling system comprising a cooling circuit
connected to a condenser of a waste heat recovery system, a cooling
pump arranged to circulate a cooling fluid through the cooling
circuit and a radiator arranged for cooling the cooling fluid, a
bypass circuit, a first valve unit and a second valve unit. The
first valve unit is arranged to control the flow of cooling fluid
through the radiator and the bypass circuit respectively, and the
second valve unit is arranged to control the flow of cooling fluid
passing through the condenser. The method steps include: [0013]
determining a condenser-in cooling fluid temperature by means of a
first temperature sensor arranged upstream of the condenser and
downstream of a first mixing point, where the cooling fluid from
the radiator and bypass circuit are mixed, and an engine-in cooling
fluid temperature by means of a second temperature sensor arranged
upstream of the internal combustion engine and downstream of a
second mixing point, where the cooling fluid from the condenser and
bypass circuit are mixed; and [0014] controlling the flow of the
cooling fluid in the cooling system by means of the first valve
unit and/or the second valve unit based on the determined
condenser-in and engine-in fluid temperatures.
[0015] The control step may comprise comparing the determined
cooling fluid temperatures with pre-defined reference cooling fluid
temperatures. In this way, an efficient control method can be
provided. The control step may comprise increasing the flow of
cooling fluid through the radiator by means of the first valve unit
if the engine-in cooling fluid temperature is higher than the
pre-defined engine-in cooling fluid temperature. In this way the
cooling effect in the cooling system may be increased. The control
step may additionally or alternatively comprise decreasing the flow
of cooling fluid from the bypass circuit via a second return pipe
to the first mixing point by means of the second valve unit, if the
condenser-in cooling fluid temperature is higher than the
pre-defined condenser-in cooling fluid temperature. Alternatively,
the flow of cooling fluid from the bypass circuit via a second
return pipe to the first mixing point can be increased by means of
the second valve unit, if the condenser-in cooling fluid
temperature is lower than the pre-defined condenser-in cooling
fluid temperature. In this way energy efficient control of the
cooling system can be provided.
[0016] The control step may comprise arranging the second valve
unit to adapt to the position of the first valve unit to thereby
control the condenser-in and/or the engine-in fluid temperature. In
this way, delays in controlling the system can be avoided.
[0017] The determination step may further comprise determining at
least one further cooling fluid temperature which is selected from
an engine-out, a radiator-out or a condenser-out cooling fluid
temperature, or a condenser-in or a condenser-out working fluid
temperature, the fluid temperatures being determined by means of a
respective third temperature sensor, fourth temperature sensor,
fifth temperature sensor, sixth temperature sensor or seventh
temperature sensor. In this way, the accuracy of the system can be
improved.
[0018] The control step may comprise lowering the pre-defined
condenser-in and engine-in cooling fluid temperatures if at least
one of the engine-out, radiator-out or condenser-out cooling fluid
temperatures or the condenser-in or condenser-out working fluid
temperatures exceeds a pre-defined value for the engine-out, a
radiator-out or a condenser-out cooling fluid temperature. A
flexible and accurate control of the cooling system can thus be
provided.
[0019] The control step can further comprise predicting coming
driving conditions by means of look-ahead active prediction
function and controlling the condenser-in and the engine-in cooling
fluid temperatures further based on the predicted driving
conditions. In this way, an energy-efficient control of the cooling
system may be achieved, and thus for example fuel consumption
reduced.
[0020] The present invention also relates to a cooling system
associated with an internal combustion engine of a vehicle, the
cooling system comprising a cooling circuit connected to a
condenser of a waste heat recovery system, a cooling pump arranged
to circulate a cooling fluid through the cooling circuit and a
radiator arranged for cooling the cooling fluid, a bypass circuit,
a first valve unit and a second valve unit, wherein the first valve
unit is arranged to control the flow of cooling fluid through the
radiator and the bypass circuit respectively, and the second valve
unit is arranged to control the flow of cooling fluid passing
through the condenser of the waste heat recovery system. The
cooling system is connected to a control unit adapted to control
the first valve unit and the second valve unit so that the flow of
the cooling fluid in the cooling system is controlled based on
temperature values determined by a first temperature sensor
arranged upstream of the condenser and downstream of a first mixing
point, where the cooling fluid from the radiator and bypass circuit
are mixed, and a second temperature sensor arranged upstream of the
internal combustion engine and downstream of a second mixing point,
where the cooling fluid from the condenser and bypass circuit are
mixed.
[0021] The cooling circuit may comprise at least one additional
temperature sensor selected from a third temperature sensor
arranged between the internal combustion engine and the first valve
unit, a fourth temperature sensor arranged between the radiator and
the first mixing point, a fifth temperature sensor arranged between
the condenser and the second mixing point, a sixth temperature
sensor arranged in the waste heat recovery system upstream of the
condenser to measure the condenser-in temperature of the working
fluid or a seventh temperature sensor arranged in the waste heat
recovery system downstream of the condenser to measure the
condenser-out temperature of the working fluid, wherein the at
least one additional temperature sensor is connected to the control
unit. By the use of additional sensor units the accuracy of the
control may be improved.
[0022] The control unit is suitably adapted to control the
engine-in temperature of the cooling fluid in the cooling circuit
by means of the first valve unit to increase the flow of cooling
fluid through the radiator and/or to reduce the flow of cooling
fluid passing through the bypass circuit by means of the second
valve unit. In this way the cooling effect may be improved and the
fluid temperature can be controlled to at least some extent without
unnecessary delays.
[0023] The cooling circuit can be arranged with one cooling pump to
circulate the cooling fluid through the cooling circuit. Thus, the
system can be made compact and the weight of the system can be
minimized.
[0024] The invention also relates to a waste heat recovery system
connected to the cooling system described above via a condenser.
Thus a compact waste heat recovery and cooling system arrangement
can be provided.
[0025] The present invention also relates to a vehicle, which
comprises a cooling system as described above or a waste heat
recovery system as described above.
[0026] The invention also relates to a computer program, wherein
said computer program comprises program code for causing an
electronic control unit or a computer connected to the electronic
control unit to perform the method steps defined above.
[0027] Furthermore, the present invention relates to a computer
program product comprising a program code stored on a
computer-readable medium for performing the method steps as defined
above, when said computer program is run on an electronic control
unit or a computer connected to the electronic control unit.
[0028] Further objects, features and advantages of the present
invention are described below in the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] For fuller understanding of the present invention and
further objects and advantages of it, the detailed description set
out below should be read together with the accompanying drawings,
in which the same reference notations denote similar items in the
various diagrams, and in which:
[0030] FIG. 1 schematically illustrates a vehicle comprising a
cooling system of the present disclosure;
[0031] FIG. 2 schematically illustrates an example embodiment of a
waste heat recovery system connected to a cooling system of the
present disclosure by means of a condenser;
[0032] FIG. 3 schematically illustrates another example embodiment
of a waste heat recovery system connected to a cooling system of
the present disclosure by means of a condenser;
[0033] FIG. 4 schematically illustrates a flow chart for a method
for controlling the temperature of a cooling system according to an
embodiment of the invention; and
[0034] FIG. 5 schematically illustrates a control unit or computer
according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0035] FIG. 1 schematically shows a side view of a vehicle 1
comprising an internal combustion engine 2, a waste heat recovery
system 4 associated with the internal combustion engine 2 and a
cooling system 6 connected to the waste heat recovery system 4. The
vehicle 1 further comprises a gearbox 8 connected to the driving
wheels 10 of the vehicle 1. The vehicle 1 may be a heavy vehicle,
e.g. a truck or a bus. The vehicle 1 may alternatively be a
passenger car. The vehicle may be a hybrid vehicle comprising an
electric machine (not shown) in addition to the combustion engine
2.
[0036] Reference is now made to FIGS. 2 and 3 which schematically
illustrate example embodiments of a cooling system of the present
invention connected to a waste heat recovery system via a
condenser. Each one of FIGS. 2 and 3 schematically shows the waste
heat recovery and the cooling systems 4, 6 arranged in fluid
connection with an internal combustion engine 2 of a vehicle 1.
[0037] Generally, the cooling system 6 may be a part of a
combustion engine cooling system and may thus cool both the
internal combustion engine and the condenser of the waste heat
recovery system. Alternatively, the cooling system is a separate
cooling system. In the embodiments shown in FIGS. 2 and 3, the
cooling system 6 is a part of the internal combustion engine
cooling system 6 and may thus cool both the internal combustion
engine 2 and the condenser 26 of the waste heat recovery system 4.
The cooling system 6 comprises a cooling circuit 50 connected to
the condenser 26 of the waste heat recovery system 4, a cooling
pump 52 arranged to circulate a cooling fluid CF through the
cooling circuit 50 and a radiator 54 arranged for cooling the
cooling fluid CF leaving the internal combustion engine 2. In the
embodiments shown in FIGS. 2 and 3, the cooling pump 52 is placed
upstream of the internal combustion engine 2 and downstream of the
condenser 26. The cooling pump 52 can be driven by the internal
combustion engine 2. A bypass circuit 56 is arranged in fluid
connection with a first return pipe 49 leading the bypass flow
towards the internal combustion engine 2, a second return pipe 48
leading the bypass flow towards the condenser 26, a first valve
unit 58 and a second valve unit 60. The cooling fluid CF is herein
illustrated as arrows also showing the flow direction of the
cooling fluid CF through the cooling circuit 50. The cooling fluid
CF may be fed via the bypass circuit 56 and the second valve 60 to
the condenser 26 via the second return pipe 48 or back to the
internal combustion engine 2 via the first return pipe 49, and the
possible directions of the flows are illustrated by arrows in FIGS.
2 and 3. The first valve unit 58 is suitably arranged to control
the flow of cooling fluid CF through the radiator 54 and the bypass
circuit 56 respectively. The second valve unit 60 is suitably
arranged to control the flow of the cooling fluid CF passing
through the condenser 26 of the waste heat recovery system 4. The
second valve unit is suitably arranged to control the flow through
the condenser by means of controlling the flow of the cooling fluid
passing through the bypass circuit 56 and the first and second
return pipes 49, 48, respectively.
[0038] The waste heat recovery system 4 connected to the cooling
system 6 is suitably arranged in a vehicle as shown in FIG. 1. The
waste heat recovery system 4 comprises a working fluid circuit 20,
wherein the working fluid is arranged to pass through an evaporator
22, an expander 24 and a condenser 26. The working fluid circuit
comprises a reservoir 28 for the working fluid WF and a pump 30
arranged to pump the working fluid WF through the circuit 20. The
evaporator 22 is arranged for heat exchange between the working
fluid WF and a heat source 32 in fluid connection with the internal
combustion engine 2. The condenser 26 of the waste heat recovery
system 4 is connected to the cooling system 6. The waste heat
recovery system 4 is fluidly connected to the heat source 32
connected to the evaporator 22, and the heat source is herein
exemplified as exhaust gases from the internal combustion engine 2.
The exhaust gases 32 are illustrated as an arrow in an exhaust
pipe, wherein the exhaust gases 32 may be controlled to pass
through the evaporator 22 or to bypass the evaporator 22. The waste
heat recovery system 4 may comprise a plurality of evaporators 22,
each connected to a different heat source 32. The evaporator 22 is
suitably a heat exchanger connected to the heat source 32 and the
working fluid circuit 20. The heat transfer between the working
fluid WF and the heat source 32 is an exchange of energy resulting
in a change in temperature. The waste heat recovery system 4 is
suitably based on an organic Rankine cycle. The working fluid WF is
thus suitably organic, such as ethanol or R245fa. The waste heat
recovery system 4 is thus configured such that the liquid working
fluid WF is pumped from low pressure to high pressure and enters
the evaporator 22. The working fluid WF is thereby heated by the
heat source 32 connected to the evaporator 22 and the working fluid
WF is thus evaporated. The vapor is then expanded in the expander
24 whereby mechanical work is produced and the temperature and the
pressure of the vapor is decreased. The mechanical work may for
example be transferred to the crankshaft of the internal combustion
engine 2 and thus be used to propel the vehicle 1 or the mechanical
work may be used to drive for example a generator. The vapor
thereafter enters the condenser 26 where condensation through heat
exchange between the vapor and the cooling fluid CF of the cooling
system 6 brings the working fluid WF back to its initial liquid
state. Thus, the heat source 32 provides energy entering the waste
heat recovery system 4 and the energy leaves the waste heat
recovery system 4 as mechanical work via the expander 24 and as
heat via the cooling system 6 cooling the condenser 26. The
temperature in the waste heat recovery system 4 depends on the
amount of energy entering the system 4 and the amount of energy
leaving the system 4. Only vapor should enter the expander 24 and
the waste heat recovery system 4 therefore comprises a bypass
arrangement 25, such that in the case where the working fluid WF is
still in a liquid state downstream of the evaporator 22, the
working fluid WF can bypass the expander 24 through the bypass
arrangement 25. The pump 30 pressurizing and circulating the
working fluid WF can be electrically driven. The WHR circuit 20 may
be arranged with only one pump, whereby the amount of heavy
components in the circuit can be minimized. The waste heat recovery
system 4 may comprise one or more evaporators/heat exchangers 22.
The waste heat recovery system 4 may for example comprise a
recuperator arranged to pre-heat the working fluid WF before
entering the evaporator 22. The waste heat recovery system 4 may
also comprise one or more condensers 26, such that cooling down of
the working fluid WF may be performed in multiple steps.
Furthermore, the waste heat recovery system 4 may comprise one or
more expanders 24. The expander 24 may be a turbine or a piston
expander.
[0039] In the cooling system 6, during the normal operating
conditions there should always be a flow of cooling fluid CF
through the radiator 54. A second valve unit 60 can mix the flow
from the radiator 54 with some hotter cooling fluid from the bypass
circuit 56 and thereby reach a desired condenser-in temperature.
The amount of the hotter cooling fluid from the bypass circuit 56
can be controlled by means of the second valve unit 60. The bypass
circuit 56 is arranged in fluid connection with the first return
pipe 49, whereby hot cooling fluid can be fed back to the internal
combustion engine if desired and with a second return pipe through
which hot cooling fluid can be fed to the condenser if desired. The
condenser-in temperature is measured by means of a first sensor
unit 55, which is connected to a control unit 40. A desired
condenser-in temperature is pre-determined as a reference fluid
temperature and the control unit 40 is arranged to control the
valve units in such a way that the desired condenser-in temperature
is reached. In the corresponding way, the engine-in temperature is
measured by means of a second sensor unit 57, and a desired
engine-in temperature is pre-determined as a reference fluid
temperature and the control unit 40 is arranged to control the
valve units such that the desired engine-in temperature is reached.
To reach the desired engine-in temperature, the first valve unit 58
is arranged to control the flow of cooling fluid CF passing through
the radiator 54 and mix it with the bypass flow if necessary. For
example, when the condenser-in temperature is too low, the second
valve unit 60 can be arranged to mix the flow through the radiator
with some hotter cooling fluid passing through the bypass circuit
56 via the second return pipe 48 and thus reach the desired
condenser-in temperature. On the other hand, when the internal
combustion engine has reached very high operating temperature it
may be necessary to lead all the cooling fluid through the radiator
by means of controlling the first valve unit accordingly. Thus, if
the engine-in temperature is too high, the first valve unit 58 can
be arranged to lead all the cooling fluid through the radiator and
correspondingly, the second valve unit 60 is adapted to decrease
the bypass flow via the second return pipe 49 if the condenser-in
temperature is too high. The control unit is suitably adapted to
control the engine-in temperature of the cooling fluid CF in the
cooling circuit 50 by means of the first valve unit 58 to increase
the flow of cooling fluid CF through the radiator 54 and/or to
reduce the flow of cooling fluid CF passing through the bypass
circuit 56 by means of the second valve unit 60.
[0040] The pipes in the cooling circuit 50 are preferably arranged
such that one cooling pump 52 is sufficient to circulate the
cooling fluid through the internal combustion engine 2 and the
condenser 26 connected to the WHR system 4. For example, the pipes
in the cooling system are suitably arranged as short as possible,
whereby a compact construction for the cooling system and suitably
the whole WHR system may be obtained. If only one pump is used, it
is preferably placed upstream of the internal combustion engine 2
and downstream of the condenser.
[0041] If the pipes in the cooling circuit are long, there may be
transport delays of the cooling fluid CF from for example from the
radiator to the condenser. Also, the cooling system may include
additional components to be cooled, such as a retarder. In this
case, there may be a desire to improve the accuracy of the cooling
system. The accuracy may be improved by incorporating at least one
additional temperature sensor to the cooling system. Reference is
made to FIG. 3 which shows additional sensor units in the cooling
system. The at least one additional sensor may be arranged between
the internal combustion engine 2 and the first valve unit 58, and
is shown as an engine-out sensor 59, herein also referred to as a
third temperature sensor. Alternatively or additionally, an
additional sensor may be arranged between the radiator 54 and the
first mixing point 51 and functions as a radiator-out sensor 61,
herein also referred to as a fourth temperature sensor. A further
sensor, referred to as a condenser-out or a fifth temperature
sensor, may be additionally or alternatively placed between the
condenser 26 and the second mixing point 53 and functions as a
condenser-out sensor. Also, in case the cooling circuit is
connected to retarder of a vehicle (not shown), a further
retarder-in and/or retarder-out sensor may be included in the
cooling system. In a further embodiment of the invention, a sixth
temperature sensor 65 may be arranged in the waste heat recovery
system 4 upstream of the condenser 26 to measure the condenser-in
temperature of the working fluid WF. According to a further
alternative, a seventh temperature sensor 67 may be arranged in the
waste heat recovery system 4 downstream of the condenser 26 to
measure the condenser-out temperature of the working fluid WF. The
extra sensors increase the control performance in the cooling
system 6. Also, in case a sensor unit is arranged in the working
fluid in the waste heat recovery system 4 to measure the
condenser-out temperature (seventh temperature sensor), the same
sensor may also be used to control the waste heat recovery WHR
system 6 and the amount of components may be reduced in the
systems. Further, it can be beneficial to include a condenser-out
sensor in the cooling circuit 50 to increase the performance of the
engine-in temperature control performance. Thereby it is possible
to control the condenser-out temperature by using the first valve
58 to control the cooling fluid CF flow and the engine-in
temperature can be controlled in an improved way to reach a
reference or desired engine-in temperature. As mentioned above, the
second valve unit 60 can mix the flow from the radiator 54 with
some hotter cooling fluid from the bypass circuit 56 and thereby
reach a desired condenser-in temperature, as long as the radiator
out temperature is sufficiently low and the radiator flow is
sufficiently high. It is also possible to arrange the first valve
unit and the second valve unit such that the second valve 60
automatically adapts to the position of the first valve 58. In this
way the time delay between valve actuation and temperature changes
can be minimized, especially in case of long pipes in the cooling
system. Also, it is possible to control the cooling system such
that the pre-defined condenser-in and engine-in cooling fluid
temperatures are lowered if at least one of the engine-out, a
radiator-out or a condenser-out cooling fluid temperature exceeds a
pre-defined value for the engine-out, radiator-out or condenser-out
cooling fluid temperature. In this way the accuracy and the
flexibility of the system may be further improved.
[0042] According to the present disclosure, the cooling system 6
comprises or is connected to the control unit 40 which is adapted
to control the flow of the cooling fluid CF in the cooling system.
The control unit is adapted to control the first valve unit 58 and
the second valve unit 60 so as to control the flow of cooling fluid
CF based on temperature values determined by the first temperature
sensor 55 arranged upstream of the condenser 26 and downstream of
the first mixing point 51, where the cooling fluid from the
radiator 54 and the bypass circuit 56 via the second return pipe 48
are mixed, and the second temperature sensor 57 arranged upstream
of the internal combustion engine 2 and downstream of a second
mixing point 53, where the cooling fluid from the condenser 26 and
bypass circuit 56 via the return pipe 49 are mixed. In this way the
first valve unit 58 can be arranged to control the flow of cooling
fluid CF through the radiator 54 and the bypass circuit 56
respectively. In FIG. 2 an embodiment of the present invention is
shown in which a condenser-in temperature value is determined by
the first temperature sensor 55 arranged upstream of the condenser
26. It is essential that the first temperature sensor 55 is placed
downstream of a first mixing point 51 where the cooling fluid from
the radiator 54 and the bypass circuit 56 via the second return
pipe 48 are mixed. The second temperature sensor 57 is arranged
upstream of the internal combustion engine 2 to determine the
engine-in temperature. Also the second sensor 57 should be placed
downstream of a second mixing point 53 where the cooling fluid from
the condenser 26 and bypass circuit 56 are mixed by means of the
second valve unit 60. The temperature sensors should be placed as
close to the mixing points of different flows as possible. However,
the flows have to have a sufficient distance to properly mix,
otherwise there is a risk that the temperature value measured is
not representative. Therefore, the sensors should be placed
downstream of the initial mixing points 51 and 53. The exact
placement of the sensor units depends on the design of the cooling
system, which in turn depends on how the waste heat recovery system
4 and the cooling system 6 are packed in a vehicle. The position
for the sensor units can be therefore calculated or tested to
assure that sufficient mixing of the fluids has occurred while the
position is as close as possible to the initial mixing points 51 or
53, respectively. Generally the mixing point of the liquids is
dependent on the design and construction of the cooling circuit,
and as an example but not limited thereto, the first sensor unit
can be arranged at a distance from the initial mixing point 51
downstream of the first mixing point, which is about 5 times the
diameter of the pipe at the first initial mixing point 51. In a
corresponding way, the second sensor unit 57 is suitably arranged
downstream of the second mixing point 53 at a distance, which is 5
times the diameter of the pipe at the second initial mixing
point.
[0043] The control unit 40 is arranged in connection to the
internal combustion engine 2, the waste heat recovery system 4 and
the cooling system 6. In the cooling system, the control unit 40 is
arranged in connection to the first valve unit 58 and to the first
sensor unit 55, the second valve unit 60 and the second sensor unit
57. In case the cooling system comprises additional temperature
sensor units 59, 61, 63, 65 or 67 to determine at least one of
engine-out, radiator-out and/or condenser-out cooling fluid CF
temperatures or condenser-out working fluid WF temperatures,
respectively, as mentioned above, also they can be connected to the
control unit 40. In the waste heat recovery system 4 the control
unit may be arranged for example in connection to the evaporator
14, the expander 16 and the pump 22 of the waste heat recovery
system 4, but other or additional connections may be possible, such
as a connection to the condenser 26. A computer 42 is suitably
connected to the control unit 40. The control unit 40 is adapted to
control the flow of the cooling fluid CF in the cooling system 6 by
controlling the flow of the cooling fluid CF based on the
determined condenser-in and engine-in fluid temperatures. Suitably,
the temperatures are then compared with predetermined reference
values in the control unit. The control of the flow is performed by
means of the first and second valve units 58, 60. The control unit
40 is suitably adapted to increase the flow of cooling fluid CF
through the radiator 54 and/or by reducing the flow of cooling
fluid CF through the bypass circuit 56 when the engine-in or the
condenser-in temperatures are too high. The control unit 40 may
also be arranged in connection with a control system of the
vehicle. Thereby it will be possible for the control unit 40 to
control the valves based also on other information in the vehicle.
For example, the control unit 40 may be arranged in connection with
a vehicle's look-ahead active prediction system, whereby it will be
possible to predict the need for reducing the temperature of the
cooling fluid depending on the expected driving conditions.
[0044] FIG. 4 shows a flowchart for controlling the temperature of
a cooling fluid in a cooling system 6 arranged in fluid connection
with an internal combustion engine 2 of a vehicle 1. The cooling
system is suitably configured as described in FIG. 2 or 3. The
method comprises the steps of: [0045] determining s101 a
condenser-in fluid temperature of the cooling fluid CF by means of
a first temperature sensor 55 arranged upstream of the condenser 26
and downstream of a first mixing point 51, where the cooling fluid
CF from the radiator 54 and bypass circuit 56 are mixed, and an
engine-in fluid temperature by means of a second temperature sensor
57 arranged upstream of the internal combustion engine 2 and
downstream of a second mixing point 53, where the cooling fluid
from the condenser 26 and bypass circuit 56 are mixed; and [0046]
controlling s102 the flow of the cooling fluid CF in the cooling
system 6 by means of the first valve unit 58 and/or the second
valve unit 60 based on the determined condenser-in and engine-in
fluid temperatures.
[0047] The method steps are suitably performed by means of the
control unit 40 connected to the internal combustion engine 2, the
waste heat recovery system 4 and the cooling system 6.
[0048] The step to control s102 the flow of the cooling fluid CF in
the cooling system 6 by means of the first valve unit 58 and/or the
second valve unit 60 based on the determined condenser-in and
engine-in fluid temperatures is suitably performed by comparing the
determined fluid temperatures with pre-defined reference fluid
temperatures. The pre-defined temperatures are preferably stored in
the control unit, e.g. in the computer connected thereto. The
temperature of the cooling fluid CF in the cooling system 6 depends
on the amount of energy entering the system 6 and the amount of
energy leaving the system 6. Basically, the warmer the engine, the
more energy enters the system. Also, since the cooling system is
connected to the condenser 26 of the waste heat recovery system
WHR, the energy entering the waste heat recovery system from the
heat source 32 also indirectly affects the temperature of the
cooling fluid CF. Therefore, by determining the condenser-in and
the engine-in temperatures, the need for controlling the flow of
cooling fluid CF by means of the first valve unit 58, and the
second valve unit 60 can be effectively determined with minimum
amount of components.
[0049] The step to control s102 the flow of the cooling fluid
suitably comprises to increase the flow of cooling fluid CF through
the radiator 54 by means of the first valve unit 58 if the
engine-in cooling fluid CF temperature is higher than the
pre-defined engine-in cooling fluid CF temperature. Also the step
to control s102 may comprise increasing the flow of cooling fluid
CF through the radiator 54 and correspondingly decrease the flow of
cooling fluid from the bypass circuit, if the condenser-in cooling
fluid CF temperature is higher than the pre-defined condenser-in
cooling fluid CF temperature, or by increasing the flow of cooling
fluid CF from the bypass circuit 56, if the condenser-in cooling
fluid CF temperature is lower than the pre-defined condenser-in
cooling fluid CF temperature. In this way, the cooling effect in
the cooling system can be improved in an efficient way and the
efficiency of the cooling system 6 is optimized during normal
operation. Thus, the cooling effect in the cooling system 6 can be
controlled such that the radiator 54 is used with full capacity.
The flow of cooling fluid CF through the radiator 54 can be
additionally increased by increasing the engine idling speed. When
the vehicle 1 is standing still the internal combustion engine 2 is
typically running with an idling speed. The cooling pump 52 is
suitably connected to the crankshaft of the combustion engine 2
such that by increasing the idling speed of the internal combustion
engine 2, the cooling pump 52 will pump an increased amount of
cooling fluid CF through the cooling circuit 50. In this way, the
flow through the radiator 54 is increased and the cooling effect is
thus increased. Also, by controlling the cooling fluid CF
temperature values in the cooling system 6 such that the
temperature values are kept as close to the pre-defined cooling
fluid temperature values as possible, engine efficiency is
optimized.
[0050] The step to control s102 the temperature of the cooling
fluid CF in the cooling system 6 suitably comprises to arrange the
second valve unit 60 to adapt to the position of the first valve
unit 58 to thereby control the condenser-in and/or the engine-in
fluid temperatures. In this way, controlling of the valve units may
be performed in an efficient and synchronized way.
[0051] The determination step s101 may further comprise determining
at least one further cooling fluid temperature which is selected
from an engine-out, a radiator-out or a condenser-out cooling fluid
temperature, the cooling fluid temperature being determined by
means of a respective third temperature sensor 59, fourth
temperature sensor 61 or fifth temperature sensor 63. Alternatively
or additionally a condenser-in or a condenser-out working fluid
temperature may be determined by means of a respective sixth
temperature 65 sensor or seventh temperature sensor 67. Suitably,
the control step s102 also comprises comparing the determined
cooling fluid CF temperatures with pre-defined reference cooling
fluid CF temperatures.
[0052] FIG. 5 schematically illustrates a device 500. The control
unit 40 and/or computer 42 described with reference to FIGS. 2 and
3 may in a version comprise the device 500. The term "link" refers
herein to a communication link which may be a physical connection
such as an optoelectronic communication line, or a non-physical
connection such as a wireless connection, e.g. a radio link or
microwave link. The device 500 comprises a non-volatile memory 520,
a data processing unit 510 and a read/write memory 550. The
non-volatile memory 520 has a first memory element 530 in which a
computer program, e.g. an operating system, is stored for
controlling the function of the device 500. The device 500 further
comprises a bus controller, a serial communication port, I/O means,
an A/D converter, a time and date input and transfer unit, an event
counter and an interruption controller (not depicted). The
non-volatile memory 520 has also a second memory element 540.
[0053] There is provided a computer program P which comprises
routines for a method for controlling the temperature of a cooling
fluid in a cooling system 6 according to the invention. The
computer program P comprises routines for determining the
condenser-in and engine-in fluid temperatures of the cooling fluid
CF based on temperature values measured by means of the first
sensor unit 55 and second sensor unit 57, respectively. The
computer program P comprises routines for controlling the flow of
the cooling fluid CF in the cooling system 6 by means of the first
valve unit 58 and/or the second valve unit 60 based on the
determined condenser-in and engine-in fluid temperatures. The
program P may be stored in an executable form or in a compressed
form in a memory 560 and/or in a read/write memory 550.
[0054] Where the data processing unit 510 is described as
performing a certain function, it means that the data processing
unit 510 effects a certain part of the program stored in the memory
560 or a certain part of the program stored in the read/write
memory 550.
[0055] The data processing device 510 can communicate with a data
port 599 via a data bus 515. The non-volatile memory 520 is
intended for communication with the data processing unit 510 via a
data bus 512. The separate memory 560 is intended to communicate
with the data processing unit 510 via a data bus 511. The
read/write memory 550 is adapted to communicating with the data
processing unit 510 via a data bus 514.
[0056] When data are received on the data port 599, they are stored
temporarily in the second memory element 540. When input data
received have been temporarily stored, the data processing unit 510
is prepared to effect code execution as described above.
[0057] Parts of the methods herein described may be effected by the
device 500 by means of the data processing unit 510 which runs the
program stored in the memory 560 or the read/write memory 550. When
the device 500 runs the program, methods herein described are
executed.
[0058] The foregoing description of the present invention is
provided for illustrative and descriptive purposes. It is not
intended to be exhaustive or to restrict the invention to the
variants described. Many modifications and variations will
obviously be apparent to one skilled in the art. The embodiments
have been chosen and described in order best to explain the
principles of the invention and its practical applications and
hence make it possible for a skilled person to understand the
invention for various embodiments and with the various
modifications appropriate to the intended use.
* * * * *