U.S. patent application number 14/358569 was filed with the patent office on 2014-11-06 for arrangement and method for cooling of coolant in a cooling system in a vehicle.
This patent application is currently assigned to SCANIA CV. The applicant listed for this patent is SCANIA CV AB. Invention is credited to Zoltan Kardos.
Application Number | 20140326443 14/358569 |
Document ID | / |
Family ID | 48668959 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140326443 |
Kind Code |
A1 |
Kardos; Zoltan |
November 6, 2014 |
ARRANGEMENT AND METHOD FOR COOLING OF COOLANT IN A COOLING SYSTEM
IN A VEHICLE
Abstract
An arrangement and a method for cooling coolant in a cooling
system in a vehicle: The cooling system includes a first cooling
circuit, a first coolant pump (11) to circulate coolant through the
first cooling circuit, a first radiator (13) to cool the coolant,
and a thermostat (12) which opens to direct coolant to the first
radiator (13) when the coolant is above the thermostat's regulating
temperature (t.sub.2); and a second cooling circuit includes a
second radiator (20) to cool coolant. A flow device (23, 29)
selectively transfers a portion of coolant from the first cooling
circuit to the second cooling circuit, so that this portion of the
coolant is cooled in the second radiator (20) when the coolant in
the first cooling circuit is within a temperature range defined by
a lowest temperature (t.sub.1) at which the coolant initially needs
cooling and a highest temperature which is equal to the
thermostat's regulating temperature (t.sub.2).
Inventors: |
Kardos; Zoltan; (Sodertalje,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCANIA CV AB |
Sodertalje |
|
SE |
|
|
Assignee: |
SCANIA CV
Sodertaje
SE
|
Family ID: |
48668959 |
Appl. No.: |
14/358569 |
Filed: |
December 3, 2012 |
PCT Filed: |
December 3, 2012 |
PCT NO: |
PCT/SE2012/051334 |
371 Date: |
May 15, 2014 |
Current U.S.
Class: |
165/287 |
Current CPC
Class: |
F01P 7/16 20130101; F01P
2060/04 20130101; F01P 2003/182 20130101; F01P 2025/32 20130101;
F01P 7/165 20130101; F01P 2060/06 20130101; F28F 27/02 20130101;
F01P 2007/146 20130101; F01P 2060/14 20130101 |
Class at
Publication: |
165/287 |
International
Class: |
F01P 7/16 20060101
F01P007/16; F28F 27/02 20060101 F28F027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2011 |
SE |
1151273-8 |
Claims
1. An arrangement for cooling of coolant in a cooling system in a
vehicle, comprising: the cooling system comprising a first cooling
circuit which comprises a first coolant pump configured and
operable to circulate coolant through the first cooling circuit, a
first radiator configured and operable to cool the coolant in the
first cooling circuit, and a thermostat at the first cooling
circuit configured to open and when open, to direct coolant to the
first radiator when the coolant in the first cooling circuit is
above a regulating temperature (t.sub.2) of the thermostat; a
second cooling circuit which comprises a second radiator for
cooling of coolant, a flow device which comprises a valve, when the
valve is in a first position, the valve is configured and operable
to direct coolant from the first cooling circuit to the second
cooling circuit, and when the valve is in a second position, the
valve is configured and operable to prevent coolant from passing
from the first cooling circuit to the second cooling circuit; and
the flow device further comprises a temperature sensor which
detects the coolant temperature at a location in the first cooling
circuit, a control unit which receives information from the
temperature sensor, wherein the control unit is configured to put
the valve into the second position when the coolant in the first
cooling circuit is at a temperature below the lowest temperature
(t.sub.1) at which the coolant initially needs cooling and is also
below the thermostat's regulating temperature (t.sub.2) and in the
first position when the coolant in the first cooling circuit is
within a temperature range defined by the lowest temperature
(t.sub.1) at which the coolant initially needs cooling and a
highest temperature which is equal to the thermostat's regulating
temperature (t.sub.2).
2. A cooling system according to claim 1, wherein the second
cooling circuit comprises a second coolant pump configured and
operable to circulate coolant through the second cooling circuit;
and the control unit is configured and operable for controlling
activation of the second coolant pump.
3. A cooling system according to claim 2, further comprising said
flow device is configured and operable to selectively either
transfer or not transfer coolant from the first cooling circuit to
the second cooling circuit in operating situations where the
coolant in the first cooling circuit is at a temperature above the
thermostat's regulating temperature (t.sub.2).
4. A cooling system according to claim 3, further comprising the
second cooling circuit comprises a first connecting line configured
and operable to lead at least a part of the coolant from the first
cooling circuit to the second cooling circuit, and a second
connecting line configured and operable to lead the coolant back to
the first cooling circuit from the second cooling circuit after the
coolant has again passed through the second radiator.
5. A cooling system according to claim 1, wherein the first
radiator and the second radiator are air-cooled.
6. A cooling system according to claim 5, wherein the first
radiator and the second radiator are situated in regions of the
vehicle such that in substantially all of the operating conditions
of the radiators, the second radiator is cooled by air which is at
a lower temperature than the first radiator.
7. A method for cooling of coolant in a cooling system in a
vehicle, wherein the cooling system comprises: a first cooling
circuit which comprises: a first coolant pump configured and
operable to circulate coolant through the first cooling circuit, a
first radiator configured and operable to cool the coolant in the
first cooling circuit, and a thermostat at the first cooling
circuit configured to open and when open, to direct coolant to the
first radiator when the coolant in the first cooling circuit is
above a regulating temperature (t.sub.2) of the thermostat; a
second cooling circuit which comprises a second radiator for
cooling of coolant and a flow device which comprises a valve, when
the valve is in a first position, the valve is configured and
operable to direct coolant from the first cooling circuit to the
second cooling circuit, and when the valve is in a second position,
the valve is configured and operable to prevent coolant from
passing from the first cooling circuit to the second cooling
circuit; and the method comprising: detecting the coolant
temperature at a location in the first cooling circuit, receiving
detected temperature information putting the valve into the second
position when the coolant in the first cooling circuit is at a
temperature below the lowest temperature (t.sub.1) at which the
coolant initially needs cooling and which is below the thermostat's
regulating temperature (t.sub.2) and putting the valve into the
first position when the coolant in the first cooling circuit is
within a temperature range defined by a lowest temperature
(t.sub.1) at which the coolant initially needs cooling and a
highest temperature which is equal to the thermostat's regulating
temperature (t.sub.2).
Description
BACKGROUND TO THE INVENTION AND PRIOR ART
[0001] The present invention relates to an arrangement and a method
for cooling of coolant in a cooling system in a vehicle according
to the preambles of claims 1 and 11.
[0002] The coolant in a cooling system for cooling of a combustion
engine in a vehicle needs to be at an operating temperature which
is usually within the range 80-90.degree. C. The cooling system
usually comprises a thermostat which regulates the coolant's
temperature in the cooling system. In operating situations where
the thermostat finds that the coolant is below the desired
operating temperature, it will be in a closed state whereby the
coolant is led to the engine without cooling. Operating situations
where the thermostat finds that the coolant is above the desired
operating temperature will put the thermostat into an operating
state in which it directs the coolant to a radiator for cooling
before it is led back to the engine. The radiator is usually
situated in the vehicle's front section where the coolant is cooled
by air forced through the radiator by a radiator fan. The radiator
which cools the coolant in the cooling system of heavy vehicles
will have a large cooling capacity and therefore be quite expensive
to procure.
[0003] Conventional thermostats switch abruptly between the closed
state and the open state, subjecting the radiator and connecting
units in the cooling system to very rapid temperature changes which
cause large thermal stresses on the material of the radiator. The
radiator and connecting units may at one moment be exposed to a
temperature of the surroundings which in winter may be extremely
low, but immediately thereafter be exposed to a temperature of
around 100.degree. C. when the thermostat opens and a large amount
of warm coolant is circulated through the radiator and the
connecting units. Problems occur in particular if the coolant's
temperature begins to oscillate about the thermostat's regulating
temperature, a situation which the radiator is very frequently
subject to large thermal stresses very likely to shorten its
service life. The service life of a radiator depends largely on how
many times it is warmed and cooled.
SUMMARY OF THE INVENTION
[0004] The object of the present invention is to propose a cooling
system in a vehicle which reduces the risk of a thermostat opening
and closing frequently and the consequent risk of a radiator in the
cooling system being frequently subject to large thermal
stresses.
[0005] The above object is achieved with the cooling system defined
in the characterising part of claim 1. The cooling system according
to the invention thus comprises a second cooling circuit with a
second radiator. When the coolant in the first cooling circuit
reaches an initial temperature at which it initially needs to be
cooled, a portion of it is led to the second cooling circuit, in
which it is cooled in the second radiator. The thermostat is closed
so that the portion of the coolant which is not led to the second
cooling circuit undergoes no cooling. The second radiator may have
a lower cooling capacity than the first radiator. When the coolant
which has been cooled in the second radiator is led back to the
first cooling circuit, it is mixed with uncooled coolant in the
first cooling circuit. The coolant which has been cooled in the
second radiator slows the coolant temperature rise in the first
cooling circuit more than it cools the coolant to a temperature
below the initial temperature at which it initially begins to be
cooled. The coolant temperature in the first cooling circuit is
thus prevented from oscillating about the initial temperature. The
second radiator will therefore not be subject frequently to thermal
stresses caused by warm coolant from the first cooling circuit
being intermittently led to the second cooling circuit. In this
operating state no coolant will thus be led to the first radiator,
which will therefore not be subject to thermal stresses caused by
rapid temperature changes.
[0006] The second radiator is thus used to regulate the coolant's
temperature within a range from the initial temperature to the
thermostat's regulating temperature. If the coolant is gradually
warmed to a temperature corresponding to the thermostat's
regulating temperature, the thermostat will open and the coolant in
the first cooling circuit will be directed automatically to the
first radiator. The thermostat has here a higher regulating
temperature than a conventional cooling system. It is less likely
to begin to open and close frequently at this rather high
temperature. If it does, there is also the possibility of adjusting
the coolant temperature in the first cooling circuit by means of
the second radiator.
[0007] According a preferred embodiment of the present invention,
said flow means comprise a valve means which in a first position
directs coolant from the first cooling circuit to the second
cooling circuit and in a second position prevents its passing from
the first cooling circuit to the second cooling circuit. A valve
means can easily and quickly be switched between the two positions.
It may with advantage be a three-way valve. Said flow means with
advantage comprise also a control unit adapted to putting the valve
means into the first position when it receives information that the
coolant in the first cooling circuit is at a temperature within
said temperature range. The control unit may be a computer unit
with suitable software for this purpose. The control unit is with
advantage adapted to receiving information from a temperature
sensor which monitors the coolant's temperature at a location in
the first cooling circuit. The sensor may for example monitor the
temperature of the coolant after it has cooled the engine in the
first cooling circuit. Alternatively, or in combination, it may
detect the temperature of the coolant before it is led to the
engine.
[0008] According a preferred embodiment of the present invention,
the second cooling circuit comprises a second coolant pump and the
control unit is adapted to controlling its activation. This second
coolant pump is with advantage in an inactive state when the
control unit has put the valve means into the first position and
coolant from the first cooling circuit is passing through the
second radiator. The first coolant pump in the first cooling
circuit may here effect the circulation both of the coolant in the
first cooling circuit and the portion of the coolant which is
circulated in the second cooling circuit. The control unit
activates the second coolant pump when coolant is to circulate
internally in the second cooling circuit. The second coolant pump
is with advantage driven electrically, since the operation of such
coolant pumps is easy to regulate.
[0009] According a preferred embodiment of the present invention,
said flow means are adapted to preventing coolant from being
transferred from the first cooling circuit to the second cooling
circuit when the coolant in the first cooling circuit is below the
lowest temperature within said range. In this situation the coolant
will not have risen to an intended operating temperature and
therefore needs no cooling. The coolant here circulates only in the
first cooling circuit, and since the thermostat is closed no
coolant is directed to the first radiator in order to be cooled. In
this operating state the cooling system works in the same way as a
conventional cooling system.
[0010] According to another preferred embodiment of the invention,
said flow means have the possibility of transferring and not
transferring coolant from the first cooling circuit to the second
cooling circuit in various operating situations where the coolant
in the first cooling circuit is above the thermostat's regulating
temperature. In operating situations which require an extra-large
cooling capacity, as when the engine is under heavy load or a
retarder is activated, it is appropriate to use both the first
radiator and the second radiator to cool the coolant in the first
cooling circuit. At other times the second cooling circuit needs to
be able to operate separately and cool components and/or media
intended to be cooled by it.
[0011] According to another preferred embodiment of the invention,
the second cooling circuit comprises a connecting line via which
coolant can be led from the first cooling circuit to the second
cooling circuit, and a connecting line via which coolant can be led
back to the first cooling circuit from the second cooling circuit
after it has again passed through the second radiator. In this case
the coolant from the first cooling circuit may pass through a
relatively limited part of the second cooling circuit which
comprises at least the second radiator.
[0012] According to another preferred embodiment of the invention,
the first radiator and the second radiator are air-cooled. They are
with advantage situated in a front section of the vehicle. They may
be situated in regions of the vehicle such that the second radiator
in substantially all operating conditions is cooled by air at a
lower temperature than the first radiator. The second radiator may
be in contact with surrounding air in the vehicle's front section,
while the first radiator is located behind the second radiator in
the front section. A radiator fan may here force a common air flow
through the two radiators. Other air-cooled cooling devices such as
charge air coolers or EGR coolers may be situated in the vehicle's
front section and be cooled by the common air flow.
[0013] The object indicated in the introduction is also achieved
with the method according to the characterising part of claim
11.
BRIEF DESCRIPTION OF THE DRAWING
[0014] A preferred embodiment of the invention is described below
by way of example with reference to the attached drawing, in
which
[0015] FIG. 1 depicts a cooling system in a vehicle according to an
embodiment of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
[0016] FIG. 1 depicts a vehicle 1 powered by combustion engine 2.
The vehicle may be a heavy vehicle and the engine a diesel engine.
The exhaust gases from the engine's cylinders are led to an exhaust
line 4 via an exhaust manifold 3. The exhaust gases in the exhaust
line 4, which will be at a positive pressure, are led to a turbine
5 of a turbo unit, thus providing the turbine with driving force
which is transferred via a connection to a compressor 6. The
compressor compresses the air led into an inlet line 8 via an air
filter 7. A charge air cooler 9 is situated in the inlet line 8 in
a region A in a front section of the vehicle. The purpose of the
charge air cooler is to cool the compressed air before it is led to
the engine. The compressed air is cooled in the charge air cooler
by air forced through the charge air cooler by a radiator fan 10
and the draught caused by the vehicle's forward movement. The
radiator fan is driven by the engine by means of a suitable
connection.
[0017] The engine 2 is cooled by coolant which is circulated in a
first cooling circuit of the cooling system by a coolant pump 11.
The first cooling circuit is provided with a thermostat 12. The
coolant in the first cooling circuit is cooled in a first radiator
13 fitted in a forward section of the vehicle in the region A. This
first radiator is situated downstream of the charge air cooler 9
with respect to the direction of cooling air flow in the region A.
The first cooling circuit comprises lines 14, 15, 16 which lead the
coolant from the first radiator to the engine. The coolant pump 11
is situated in the line 16. The first cooling circuit comprises
lines 17, 18 which lead the coolant from the engine to the first
radiator 13. The line 17 comprises a retarder cooler 19 to cool
hydraulic oil in a hydraulic retarder. When the coolant is below
the thermostat's regulating temperature, the thermostat directs the
coolant from the line 17 to the engine via the lines 15, 16, a
situation in which the coolant is therefore not cooled in the first
radiator 13. When the coolant is above the thermost's regulating
temperature, the thermostat directs it to the first radiator for
cooling. The first cooling circuit is substantially similar to a
conventional system for cooling a combustion engine, but with a
difference in that the thermostat has a higher regulating
temperature than that in a conventional cooling system.
[0018] The cooling system comprises not only the first cooling
circuit described above but also a second cooling circuit
containing a second radiator 20 provided with a second coolant pump
28 to circulate coolant in the second cooling circuit. This second
coolant pump is situated in a line 22 in the second cooling
circuit. A valve means in the form of a three-way valve 23 is
connected to the line 22. When this valve is put into a second
position, it directs the coolant from the line 22 to a line 24 and
a second radiator 20 in the second cooling circuit. The second
cooling circuit comprises also a line 25 which leads cold coolant
from the second radiator 20 to an AC condenser 26 and a gearbox
cooler 27. The line 25 is connected to the line 22. When the second
coolant pump 28 is activated and the three-way valve 23 is in the
second position, coolant is circulated through the second radiator.
The coolant's temperature in the second cooling circuit will in
substantially all operating states be lower than that of the
coolant in the first cooling circuit, since the coolant can here be
cooled by air at the temperature of the surroundings. The
refrigerant in the AC condenser 26 and the gearbox oil in the heat
exchanger 27 can therefore be cooled to relatively low
temperatures.
[0019] Coolant from the first cooling circuit may be transferred to
the second cooling circuit via a first connecting line 21a
connected to the three-way valve 23. This first connecting line may
thus lead coolant from the line 16 in the first cooling circuit to
the three-way valve. When the three-way valve is in a first
position, it directs coolant from the first line 21a to the line 24
and the second radiator 20. After it has passed through the second
radiator, the coolant is led via the line 25 to a second connecting
line 21b which leads it back to the line 15 in the first cooling
circuit. The cooling system comprises a control unit 29 to control
the three-way valve 23 and the activation of the second coolant
pump 28. In this case the control unit 29 receives information from
a temperature sensor 30 which monitors the coolant's temperature in
the line 17 at a location which is downstream of the engine 2 and
upstream of the retarder cooler 19.
[0020] During operation of the vehicle, the control unit 29
substantially continuously receives information from the
temperature sensor 30 about the coolant temperature in the first
cooling circuit. After start-up, the coolant will be below an
initial temperature t.sub.1 when its cooling needs to begin. This
initial temperature t.sub.1 may for example be 80.degree. C. When
the coolant is at a temperature below t.sub.1, the control unit
will put the three-way valve 23 into the second position whereby no
coolant is transferred from the first cooling circuit to the second
cooling circuit. The thermostat 12 has a regulating temperature
t.sub.2 which is higher than the initial temperature t.sub.1. This
regulating temperature may for example be 90.degree. C. The
thermostat is therefore closed when the coolant is below t.sub.1.
It will therefore direct no coolant to the first radiator 13, and
the coolant will be led back to the first coolant pump 11 and the
engine 2 without cooling. In this operating state when the coolant
is below the initial temperature t.sub.1, the first cooling circuit
may work in a similar way to a conventional cooling system. In this
operating state there is normally no need for any cooling of the
coolant in the second cooling circuit and the control unit 29 will
not normally activate the second coolant pump 28, but it is
possible to activate the second coolant pump 28 and circulate the
coolant in the second cooling circuit if so desired.
[0021] The coolant in the first cooling circuit is progressively
warmed by the engine 2. When the control unit receives information
from the temperature sensor 30 that the coolant has reached the
initial temperature t.sub.1, it puts the three-way valve 23 into
the first position. It also ensures that the second coolant pump 28
is not in operation. Part of the coolant flow in the line 16 will
thus pass through the first connecting line 21a to the three-way
valve 23, which directs the coolant to the line 24 and the second
radiator 20 in the second cooling circuit. The coolant is cooled in
the second radiator by air at the temperature of the surroundings
before being led through the AC condenser 26 in which it cools the
refrigerant in the AC installation, and the heat exchanger 27 in
which it cools the gearbox oil. The coolant is then led via the
second connecting line 21b to the line 15 and thus back to the
first cooling circuit. The cold coolant is here mixed with coolant
from the thermostat 12, which will thus be at a temperature higher
than the initial temperature t.sub.1 but lower than the
thermostat's regulating temperature t.sub.2. The cold coolant which
has been cooled in the second radiator 20 thus undergoes cooling by
the coolant which comes from the thermostat. The magnitude of this
cooling depends inter alia on how much of the coolant in the first
cooling circuit is cooled in the second radiator.
[0022] The second radiator 20 is significantly smaller than the
first radiator 13. Although it uses air at the temperature of the
surroundings to cool the coolant in it, it has significantly less
cooling capacity than the first radiator. The cooling effect upon
the coolant when mixed with the cold coolant from the second
radiator is therefore clearly less than if the whole coolant flow
in the first cooling circuit passed through the first radiator. The
increase in the coolant temperature t is halted but the cooling of
the coolant is not sufficient to bring it back below the initial
temperature t.sub.1. The possibility of the coolant's temperature
beginning to oscillate between below and above the initial
temperature t.sub.1 is thus prevented in most situations, which
means that its temperature may often stay within the range between
t.sub.1 and t.sub.2 for a relatively long period of operation of
the vehicle. A continuous coolant flow is in this case led to the
second radiator 20 and is therefore not subject to any large
thermal stresses caused by rapid temperature changes. During such a
period of operation, the first radiator 13 will also be at a
substantially constant temperature when not receiving any coolant
at all and will therefore likewise not be subject to any large
thermal stresses caused by rapid temperature changes.
[0023] If surrounding air is not too cold, the coolant's
temperature will rise in certain operating states of the engine 2
to above the regulating temperature t.sub.2 of the thermostat. When
this happens, the thermostat will open and the coolant in the first
cooling circuit be directed to the first radiator 13 in order to be
cooled before being used again to cool the engine. When the control
unit 29 receives information that the coolant is above the
thermostat's regulating temperature t.sub.2, it will put the
three-way valve 23 into the second position, thereby halting the
coolant flow from the first cooling circuit to the second cooling
circuit. At the same time, it will set the second coolant pump 28
running to start the circulation in the second cooling circuit.
When the three-way valve is in the second position, the first
cooling circuit and the second cooling circuit function as two
separate circuits. In this case the engine is therefore cooled by
the coolant in the first cooling circuit, and the media in the heat
exchangers 26, 27 by the coolant in the second cooling circuit. In
this operating state, the coolant in the second cooling circuit
will be at a clearly lower temperature than that in the first
cooling circuit. This means that the media in the heat exchangers
26, 27 can be cooled to close to the temperature of the
surroundings. There is a risk that the coolant may reach
temperatures which oscillate about the thermostat's regulating
temperature t.sub.2, but this risk is not so great at this raised
regulating temperature t.sub.2 of the thermostat 12.
[0024] The thermostat thus has a significantly higher regulating
temperature t.sub.2 than a conventional thermostat with a
regulating temperature corresponding to the initial temperature
t.sub.1. The difference between t.sub.1 and t.sub.2 may be of the
order of 10.degree. C., which means that the regulating temperature
t.sub.2 is not reached as often as the initial temperature t.sub.1.
The present cooling system also affords the possibility of varying
the cooling of the coolant in the first cooling circuit by
switching the three-way valve, making it possible to alter the
coolant's temperature and thereby prevent any possible temperature
cycling about the regulating temperature t.sub.2.
[0025] There are also other situations in which it may be
appropriate to direct coolant from the first cooling circuit to the
second cooling circuit, e.g. if the control unit 29 receives
information that there is risk of ice forming in the charge air
cooler 9. The control unit may receive such information from a
temperature sensor which monitors the temperature of the charge air
close to the charge air cooler. Putting the three-way valve into
the first position will direct relatively coolant from the line 16
in the first line circuit to the second radiator 20. The air which
flows through the second radiator will thus undergo a marked
temperature rise. The air reaching the charge air cooler 9
downstream will thus be at a clearly higher temperature than
0.degree. C., causing any ice formed within the charge air cooler
to melt. When the control unit receives information that the
temperature of the charge air has risen back to an acceptable
level, it will put the three-way valve 23 into the second position.
Another occasion for putting the three-way valve into the first
position is operating situations in which the engine is under heavy
load or the retarder is activated. Such situations require a high
cooling capacity for the coolant in the first cooling circuit. In
this case the coolant may be cooled both in the first radiator 13
and in the second radiator 20, reducing the risk of the cooling
system being overloaded.
[0026] The cooling system indicated above thus has several
advantages. The problem of the thermostat switching frequently and
warm coolant being led at short intervals to a cold radiator can be
substantially eliminated. The service life of the first radiator 13
may therefore be considerably lengthened with a cooling system
according to the present invention. The possibility is afforded of
increasing the coolant's temperature at low loads, reducing fuel
consumption. Moreover, the first cooling circuit may where
necessary provide increased cooling capacity through the
possibility of also using both the first radiator and the second
radiator to cool the coolant.
[0027] The invention is in no way restricted to the embodiments
described but may be varied freely within the scopes of the
claims.
* * * * *