U.S. patent application number 09/729775 was filed with the patent office on 2001-08-16 for motorized thermostatic device with backup thermostatic element.
Invention is credited to Chamot, Jean-Pierre, Le Clanche, Gerard Jean Andre.
Application Number | 20010013553 09/729775 |
Document ID | / |
Family ID | 9552983 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013553 |
Kind Code |
A1 |
Chamot, Jean-Pierre ; et
al. |
August 16, 2001 |
Motorized thermostatic device with backup thermostatic element
Abstract
A housing (1) has a chamber (10) comprising fluid accesses (41,
42, 43, 44), at least one of which can be plugged by a plug (2); a
reversible motor (6) equipped with a rotary shaft is connected to
the plug by a coupling (7) involving a screw-nut system (71) to
move it in translation towards plugging or uncovering the pluggable
access (41) according to the temperature of a stream of fluid
travelling through the device; and a thermostatic element (8)
located in the same stream of fluid actuates the plug if the motor
or its controls fail. In order to prevent the plug (2) from then
reverting to its initial position when the element (8) retracts,
the coupling (7) is inelastic and the screw-nut system (71) is
reversible so that when the plug is actuated by the thermostatic
element, the motor (6) is made to rotate. Use: internal combustion
engine cooling circuit.
Inventors: |
Chamot, Jean-Pierre;
(Arpajon, FR) ; Le Clanche, Gerard Jean Andre;
(Draveil, FR) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
Suite 800
2033 K Street, N.W.
Washington
DC
20006
US
|
Family ID: |
9552983 |
Appl. No.: |
09/729775 |
Filed: |
December 6, 2000 |
Current U.S.
Class: |
236/12.11 ;
236/12.1 |
Current CPC
Class: |
G05D 23/1393 20130101;
F01P 2031/32 20130101; F16K 31/04 20130101; F01P 7/167
20130101 |
Class at
Publication: |
236/12.11 ;
236/12.1 |
International
Class: |
G05D 023/13 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 7, 1999 |
FR |
99 15429 |
Claims
1. Thermostatic device comprising a housing (1) which has a chamber
(10) comprising at least two fluid accesses (41, 42, 43, 44; 41,
44), at least one of which can be plugged by a plug (2; 2'), a
motor (6) fixed to the housing and equipped with an output shaft
that is able to move in terms of rotation and with reversible
direction of rotation, connected mechanically to the plug by a
coupling (7) involving a screw-nut system (71) designed to actuate
this plug in terms of translation, selectively, in a direction in
which it gradually plugs the pluggable access (41) and in a
direction in which it gradually uncovers it according to the
temperature of a stream of fluid travelling through the device and
detected by a sensor (9), and a backup thermostatic element (8)
located at least partially in the same stream of fluid and
comprising a moving part (81) designed to actuate the plug in terms
of translation when, as the result of a failure, this plug has not
been actuated by the screw-nut coupling system and the temperature
of the said stream of fluid exceeds by a predetermined value the
temperature that should have caused such actuation by the screw-nut
system, characterized in that the motor (6) is of a type which, at
rest, presents a resistive torque so as to allow a set position to
be maintained, the coupling (7) involving a screw-nut system (71)
is substantially inelastic and the screw-nut system is reversible
so that if the plug (2; 2') is actuated in terms of translation by
the moving part (81) of the thermostatic element (8), the
translational movement is transmitted by the plug to the screw-nut
system and causes the motor (6) to rotate.
2. Thermostatic device according to claim 1, characterized in that
the motor (6) is an electric motor of a type which is electrically
powered at rest so that it presents a resistive torque that is
appreciably higher than the torque due to friction, for example a
stepping motor or a motor with no commutator otherwise known as a
brushless motor.
3. Thermostatic device according to claim 1, characterized in that
the motor (6) is a stepping motor equipped with position-encoding
means.
4. Thermostatic device according to claim 1, characterized in that
the predetermined value is about 5.degree. C.
5. Thermostatic device according to claim 1, characterized in that
it comprises a housing (1) and a base (1') fixed together, the base
(1') comprising a pipe (14) into which there opens an access (44)
of the chamber which is not pluggable and in which a sensor (9) and
a fixed part (80) of the thermostatic element (8) are at least
partially situated.
6. Thermostatic device according to claim 1, characterized in that
the chamber (10) comprises two accesses (41, 43) that can be
plugged by a plug (2) consisting of a spool actuated selectively in
a direction in which it gradually plugs one of the accesses while
gradually uncovering the other, and vice versa.
7. Thermostatic device according to claim 6, characterized in that
it further comprises two accesses (42, 44) which cannot be plugged
by the plug (2) and which are constantly in communication.
8. Thermostatic device according to claim 1, characterized in that
the chamber (10) comprises two accesses (41, 44), one of which can
be plugged by a plug (2') consisting of a shutter actuated
selectively in a direction in which it gradually plugs one of the
accesses and vice versa.
9. Thermostatic device according to claim 8, characterized in that
it comprises a housing (1) and a base (1') fixed together, the base
(1') comprising a pipe (14) into which there opens an access (44)
of the chamber which is not pluggable and into the side wall of
which there opens an additional access (43) which is also not
pluggable.
10. Thermostatic device according to claim 9, characterized in that
the thermostatic element (8) comprises a cup (80) to which a bypass
sealing shutter (87) is secured, and the base (1') internally
comprises a chamber (10') into which there opens a bypass access
(12') and which is connected to the internal region of the pipe
(14) by a seat (11') for the bypass sealing shutter (87) which is
in the widest-open position when the plug (2') is in the closed
position and in the closed position when the sensor (9) detects a
very high temperature.
Description
[0001] The invention relates to a thermostatic device of the
electric-motor-actuated valve type comprising a thermostatic
element which may be a conventional expanding-wax thermostatic
element so that it also has a backup mode of operation in the event
of failure of the motor or of its control equipment.
[0002] Thermostatic devices of the valve type are used in
particular in internal combustion engine cooling circuits to
regulate the temperature of the cooling liquid introduced into this
engine to optimize its operation, by influencing the flowrate of
so-called "cold" liquid from the vehicle radiator and/or the
flowrate of so-called "hot" liquid from the engine, which are mixed
to form a so-called "warm" cooling liquid which is reintroduced
into the engine. Note that the terms "cold", "hot", and "warm" are
used with a view to simplifying the vocabulary used to indicate the
relative temperature levels of the three streams of liquid when the
device is operating in the steady state, but that in fact the
respective temperatures of these three streams may be very similar,
and are identical when the engine has been stopped for some
time.
[0003] Thermostatic devices motorized by means of an electric motor
comprising a backup thermostatic element allowing, for example, a
stream of cold liquid to be mixed in a chamber of the device with
the stream of hot liquid even when the motor or its control
equipment fail, if the temperature of the liquid in which the
thermostatic element is immersed exceeds a desired value, are
already known, particularly from French patent published under the
number 2 703 730.
[0004] The thermostatic device in this document 2 703 730 is
motorized by means of an electric motor comprising a rotary output
shaft which, by means of a conventional screw-nut coupling system
converting the rotary movement of the shaft into a translational
movement, actuates the moving plug of the thermostatic device,
namely a spool, which gradually uncovers a cold liquid inlet access
of this device at the same time as gradually plugging a hot liquid
inlet access, and vice versa; the backup thermostatic element is
aligned with the screw of the screw-nut system and when its
temperature rises, its piston exerts on the spool, if the latter
has not been moved or has been insufficiently moved, via the
screw-nut system, a force directed in the direction for uncovering
the cold liquid inlet access and plugging the hot liquid inlet
access; so that under the thrust of the piston of the thermostatic
element, the spool can actually move in this direction, the
screw-nut system coupling is telescopic and, more specifically,
mounted so that it can slide on the shaft of the motor while being
urged toward the spool by a spring in the direction for uncovering
the hot liquid inlet access and plugging the cold liquid inlet
access; hence, when the thermostatic element exerts on the spool a
force in the opposite direction which exceeds the spring force, to
plug the hot liquid inlet access and uncover the cold liquid inlet
access, the spring is compressed by the retraction of the screw-nut
system and so nothing opposes these respective plugging and
uncovering movements. A drawback with this device is that when the
temperature of the liquid in which the thermostatic element is
immersed drops, the screw-nut system accompanies the retracting
movement of the thermostatic element which, because the electric
motor or its control equipment has failed, leads to a further
temperature rise, a further elongation of the thermostatic element,
and operation which tends towards the unstable with a "warm" liquid
at a temperature higher than the normal temperature. Furthermore,
the thermostatic element has to be relatively powerful in order to
overcome the resistive force of the spring, and the screw-nut
system with its telescopic spring-loaded mounting is relatively
bulky, which means that the dimensions of the thermostatic device
cannot be reduced as much as might be desired.
[0005] The object of the invention is to overcome these drawbacks
and the invention therefore relates to a thermostatic device
comprising a housing which has a chamber comprising at least two
fluid accesses, at least one of which can be plugged by a plug, a
motor fixed to the housing and equipped with an output shaft that
is able to move in terms of rotation and with reversible direction
of rotation, connected mechanically to the plug by a coupling
involving a screw-nut system designed to actuate this plug in terms
of translation, selectively, in a direction in which it gradually
plugs the pluggable access and in a direction in which it gradually
uncovers it according to the temperature of a stream of fluid
travelling through the device and detected by a sensor, and a
backup thermostatic element located at least partially in the same
stream of fluid and comprising a moving part designed to actuate
the plug in terms of translation when, as the result of a failure,
this plug has not been actuated by the screw-nut coupling system
and the temperature of the said stream of fluid exceeds by a
predetermined value the temperature that should have caused such
actuation by the screw-nut system, characterized in that the motor
is of a type which, at rest, presents a resistive torque so as to
allow a set position to be maintained, the coupling involving a
screw-nut system is substantially inelastic and the screw-nut
system is reversible so that if the plug is actuated in terms of
translation by the moving part of the thermostatic element, the
translational movement is transmitted by the plug to the screw-nut
system and causes the motor to rotate.
[0006] Owing to the reversibility of the screw-nut system and of
the direction of rotation of the motor and to the translational
inelasticity of the coupling, movements of the plug by the
thermostatic element encounter only a low resistive force, and
retraction of the thermostatic element does not cause elastic
return of the plug to its initial position.
[0007] The thermostatic device may furthermore exhibit one or more
of the following features:
[0008] the motor is an electric motor of a type which is
electrically powered at rest so that it presents a resistive torque
that is appreciably higher than the torque due to friction, for
example a stepping motor or a motor with no commutator otherwise
known as a brushless motor,
[0009] the motor is a stepping motor equipped with
position-encoding means,
[0010] the predetermined value is about 5.degree. C.,
[0011] it comprises a housing and a base fixed together, the base
comprising a pipe into which there opens an access of the chamber
which is not pluggable and in which a sensor and a fixed part of
the thermostatic element are at least partially situated,
[0012] the chamber comprises two accesses that can be plugged by a
plug consisting of a spool actuated selectively in a direction in
which it gradually plugs one of the accesses while gradually
uncovering the other, and vice versa,
[0013] it further comprises two accesses which cannot be plugged by
the plug and which are constantly in communication,
[0014] the chamber comprises two accesses, one of which can be
plugged by a plug consisting of a shutter actuated selectively in a
direction in which it gradually plugs one of the accesses and vice
versa,
[0015] it comprises a housing and a base fixed together, the base
comprising a pipe into which there opens an access of the chamber
which is not pluggable and into the side wall of which there opens
an additional access which is also not pluggable,
[0016] the thermostatic element comprises a cup to which a bypass
sealing shutter is secured, and the base internally comprises a
chamber into which there opens a bypass access and which is
connected to the internal region of the pipe by a seat for the
bypass sealing shutter which is in the widest-open position when
the plug is in the closed position and in the closed position when
the sensor detects a very high temperature.
[0017] Other features and advantages of the invention will emerge
from the description which will follow of some embodiments of the
invention which are given by way of non-limiting examples,
illustrated by the appended drawings in which:
[0018] FIGS. 1 and 2 diagrammatically show a first embodiment of
the thermostatic device according to the invention respectively in
a state in which the moving plug of the device is subjected to the
action of the motor in the absence of failure thereof and/or of its
control equipment, and in a state in which the motor and/or its
control equipment have failed and the backup thermostatic element
has taken over to lower the temperature of the warm fluid, for
example a liquid,
[0019] FIGS. 3 and 4 diagrammatically show a second embodiment of
the thermostatic device according to the invention, in the same two
states as in FIGS. 1 and 2 respectively, and
[0020] FIG. 5 diagrammatically shows an alternative form of the
device of FIGS. 3 and 4.
[0021] The thermostatic device depicted diagrammatically in FIGS. 1
and 2 is a spool-type thermostatic valve with four fluid accesses
or ports which may be fluid inlets or outlets according to the
hydraulic circuit in which the device is inserted.
[0022] It comprises a housing 1 having a chamber 10 in which there
is mounted, so that it can slide, a plug 2 consisting of a hollow
spool comprising a skirt 21 of cylindrical overall shape and, at
one end of this skirt, a perforated end 22 whose role will be
explained later on, while the opposite end of the skirt has a
flared part in the form of a flat annular disc 23.
[0023] The spool is guided in its sliding movement along the
longitudinal central axis of its cylindrical skirt by a cylindrical
wall part 101 of the chamber, with the insertion of a seal 3; this
cylindrical wall part 101 surrounds the spool 2 near its perforated
end 22.
[0024] Opening into the wall in the region of the chamber 10
outside the skirt, at the same end as the perforated end 22, is a
first fluid access 41 in the lateral part of this wall, and a
second fluid access 42 centred on the longitudinal central axis of
the skirt in the bottom part of the wall placed facing the
perforated end 22; the first fluid access 41 can therefore be
plugged by the skirt of the spool gradually from a position of the
spool in which its end 22 is flush with the access 41, to a
position in which this perforated end 22 butts against the bottom
part of the wall of the chamber into which the second access 42
opens (in this instance without plugging this access), and can be
gradually uncovered in the opposite direction.
[0025] Opening into the lateral part of the wall of the chamber 10
outside the skirt which is opposite the latter when the first
access 41 is completely uncovered is a third fluid access 43 which
is therefore completely plugged by the skirt when the first access
41 is completely uncovered, and which is gradually uncovered by it
when this first access is gradually plugged (and vice versa).
[0026] Finally, a fourth access 44, centred on the longitudinal
axis of the skirt and which is not pluggable by this skirt, opens
into the wall of the region of the chamber 10 inside the skirt
opposite the one which has the second access 42.
[0027] The first access 41 and the third access 43 which are
pluggable by the skirt 21 are end orifices of pipes 11, 13 formed
in one piece with the housing 1 and which extend in a radial
direction with respect to the skirt, starting from the lateral wall
of the chamber. The second access 42 is an end orifice of an
elbowed pipe 12, of which the part located beyond the elbow
starting from the second access extends in the same direction as
the second pipe 12, but in this instance in the opposite sense. The
fourth access 44 of the chamber 10 opens directly, the housing 1
being designed to be fixed to a housing base 1' to which the
housing 1 can be fixed by screws passing through respective flanges
of the housing 1 and of the base 1'; in this instance, the chamber
10 is therefore extended, beyond the fourth access 44, by a pipe 14
belonging to the base 1', extending in the direction of the
longitudinal central axis of the skirt 21.
[0028] A spool seat 5, perforated for reasons which will be
explained later on, extending in the fourth access 44, is trapped
between the housing 1 and the base 1'; a part of this seat 5,
extending anularly into the fourth access 44, has one annular face
51 facing towards the inside of the chamber and, more precisely,
towards the perforated end 22 of the skirt, this face 51 acting as
a seat for the flared disc-shaped part 23 of the skirt of the
spool.
[0029] To actuate the spool 2 in translation selectively in one
direction or the other along the longitudinal central axis of the
skirt 21, an actuator 6 is fixed to the housing and, more
precisely, to the lateral wall of the second pipe 12. This actuator
consists of an electric motor 6 equipped with an output shaft which
can move in rotation and has a reversible direction of rotation, of
the stepping type or type with no commutator also known as
brushless motor, or alternatively of some other type which, when
electrically powered at rest, then presents a resistive torque
which is appreciably higher than that due to friction so as to
allow a set position to be maintained, carrying a mechanical
coupling 7 for connecting the output shaft to the spool, this
coupling 7 comprising a screw-nut system 71 (the details of which
are not depicted in the figures) which is itself reversible. In the
case of a stepping motor, a motor equipped with position-encoding
means allowing the amplitudes of the movements performed to be
identified may advantageously be chosen.
[0030] By means of the screw-nut system 71, the rotary stepping
movement of the output shaft of the motor 6 is converted into a
stepping translation movement of an output piston 72 of the
screw-nut system.
[0031] The free end of the output piston 72 is screwed into one end
of a shaft 73 that controls the plug 2, emerging in the chamber 10,
and the opposite end of which is fixed to the central region of the
end 22 of the plug.
[0032] For this purpose, this end 22 comprises a central hole into
which the control shaft 73 is clipped; the material surrounding the
central hole is connected to the skirt by one or more bridges of
material extending in radial planes of the skirt 21, and between
which perforations or openings are defined, these being intended to
allow fluid transfers between the second access 42 and the fourth
access 44 of the chamber 10 under all circumstances; it will be
noted that the mechanical coupling 7 extending from the rotary
output shaft of the motor 6 to the end of the spool 2 is not
elastically retractable, its retraction being possible only as the
result of the reversibility of the screw-nut system without elastic
return to a more extended position.
[0033] The thermostatic device also carries a backup independent
expanding-wax thermostatic element 8 and, for this purpose, in the
same way, the seat 5 for the spool 2 comprises a central disc
pierced with a central hole in which the thermostatic element 8 is
fixed; the central disc is connected to the annular part of the
seat 5 by one or more bridges of material extending along radial
planes with respect to the skirt 21, between which are defined
perforations or openings intended to allow fluid transfers between
the fourth access 44 and the chamber 10. Part of the thermostatic
element 8, in this instance its cup 80 containing the wax, is
placed directly and held fixedly in the pipe 14 extending into the
base 1' and therefore into the stream of fluid travelling through
this pipe 14.
[0034] Another part of the thermostatic element 8, comprising its
piston 81, is housed in a flange 82 of cylindrical overall shape
fixed to the fixed part of the thermostatic element and extending
into the skirt 21 like the piston 81 towards the end of the control
shaft 73 which is fixed into the end 22 of the spool; as the piston
81, which here constitutes the moving part of the thermostatic
element, is relatively short, it is extended into the flange 82 by
an operating spindle 83 designed to project out of the free end of
the flange 82 when the temperature of the fluid in the pipe 14 is
higher than a predetermined temperature.
[0035] The operating spindle 83 comprises, at the same end as the
fixed part of the thermostatic element, a base piece which is
subjected to the action of a helical return spring 84 compressed
between this base piece and the internal face of the free end of
the flange 82; thus, when the temperature of the stream of fluid in
which the cup of the thermostatic element is immersed drops
following elongation of the piston 81 and of the operating spindle
83, the spindle 83 and the piston 81 are returned to the retracted
position.
[0036] In addition, a temperature sensor 9 projecting into the pipe
34 of the base 1' near the cup of the thermostatic element is
mounted on the lateral wall of this pipe; the purpose of this
sensor is to detect the temperature of the stream of fluid in this
pipe and, in response, to transmit an electrical signal of the
detected temperature to a computer (not depicted) controlling the
motor 6. The computer, receiving this signal about the temperature
detected, controls the motor 6 so that the latter actuates the
spool 2 either in proportion to the difference between the
detected-temperature signal and a setpoint temperature signal it
generates on the basis of, for example, the running conditions, and
therefore in proportion to the difference between the detected
temperature and the setpoint temperature, or on the basis of some
other non-proportional chosen algorithm.
[0037] Thus, the output shaft of the motor 6 is actuated in
rotation in one direction or the other according to the direction
of the variations in temperature of the fluid in the pipe 14 of the
base 1' which are detected by the sensor 9 and moves the spool 2 in
translation in one direction or the other via the inelastic
reversible screw-nut mechanical coupling system 7 in proportion to
the difference between the temperatures or according to some other
algorithm.
[0038] When there is a rise in temperature, the movement of the
coupling 7 is a retraction which gradually causes the first access
41 to be plugged and the third access 43 to be uncovered; when
there is a reduction in temperature, the movement of the coupling 7
is an extension which gradually causes the uncovering of the first
access 41 and the plugging of the third access 43.
[0039] Assuming that the motor 6, the sensor 9 or the computer, or
any other item in the control sequence located between the sensor
and the motor is experiencing a failure and the spool 2 is thus not
actuated in terms of translation in the direction for plugging the
first access 11 and uncovering the third access 43 even though it
should have been, given the temperature of the fluid, the moving
part of the thermostatic element (that is to say, in this instance,
its piston) which also extends and retracts as the temperature in
the pipe 14 of the base 1 respectively rises and falls, takes over
from the motor 6 to actuate the spool in terms of translation as
soon as the temperature of the stream of fluid exceeds by a certain
value, for example by 5.degree. C., the temperature which should
have caused actuation by the normal actuating sequence involving
the screw-nut system (FIG. 2). As the coupling 7 is inelastic and
the screw-nut system 71 is reversible, the translational movement
of the spool 2 imparted to the control shaft 73 causes, via the
screw-nut system 71, a rotation of the motor which, to within the
amount of, in this instance, 5.degree. C., corresponds to the
rotation that the motor should have effected; furthermore, the
spool 2 remains in the same position even if the thermostatic
element cools.
[0040] It may be noted that the setting modes prescribed by the
computer no longer then meet the requirements, and that signals
indicating failure can then be created.
[0041] It may also be noted that the value of the temperature
threshold that triggers the intervention of the thermostatic
element 8 is determined by the characteristics of the two actuating
sequences for the spool 2 (the one involving the motor and the one
involving the thermostatic element) and also by the distance
separating the free end of the operating spindle 83 from that of
the control shaft 73 in normal operating conditions.
[0042] There are various possible configurations of cooling circuit
for an internal combustion engine, for example of a vehicle.
[0043] In a first configuration, the outlet from the internal
combustion engine is connected to the inlet of a radiator and to
the inlets of various pieces of equipment such as a unit heater, a
gearbox oil heat exchanger and an engine oil heat exchanger, and
the first access 41 is connected to the line connecting, on the one
hand, the radiator and, on the other hand, the engine and these
pieces of equipment; it is therefore a hot fluid inlet. The second
access 42 is connected to the outlet of the equipment items
mentioned above and is therefore a less-hot fluid inlet. The third
access 43 is connected to the outlet of the radiator and is a cold
fluid inlet. The fourth access 44 is connected to the inlet of the
engine via a circulating pump and is a fluid outlet which may be at
the temperature of the fluid leaving the engine or the fluid
leaving the radiator, or at a lower temperature depending on
whether the plug is fully opening the first access and closing the
third, or closing the first access, or occupying an intermediate
position, depending on the algorithm in the computer, in this
instance the vehicle on-board computer.
[0044] In a second configuration, the outlet from the internal
combustion engine is connected to the fourth access 44, and this is
a hot fluid inlet; the third access 43 is connected to the inlet of
the cooling radiator and is a hot fluid outlet because it is always
more or less in communication with the fourth access; the first
access 41 is connected to the inlet of the engine via the pump, and
is therefore an outlet which, when this access is not plugged, is a
hot fluid outlet; the second access 42 is connected to the inlets
of the other equipment items already mentioned and is a hot fluid
outlet because it is always in communication with the fourth
access; the outlets from the radiator and from the other equipment
items are also connected to the inlet of the engine via the pump.
In this case, the thermostatic device does not act as a mixer but
splits the inlet hot fluid between the engine, the radiator and the
other items of equipment so that the engine receives cooling fluid
at the appropriate temperature.
[0045] In both instances, appropriate means are provided to check
that the thermostatic device is "open" (first access 41 uncovered)
for cold-starting the engine.
[0046] The thermostatic device depicted diagrammatically in FIGS. 3
and 4 is a shutter-type thermostatic valve with three fluid
accesses or ports which may be fluid inlets or outlets depending on
the hydraulic circuit in which the device is inserted.
[0047] In FIGS. 3 and 4 and in the remainder of the text, elements
which correspond identically or approximately to elements in FIGS.
1 and 2 and the earlier part of the description carry the same
numerical references.
[0048] This thermostatic device comprises a housing 1 with a
chamber 10 of cylindrical overall shape and a plug 2' mounted to
slide in the housing and consisting of a shutter.
[0049] The chamber 10 comprises a first access 41 which can be
plugged by the shutter 2' and for this purpose has a frustoconical
seat 411 flaring towards the outside of the chamber to bear on the
lateral wall of the shutter; this first access 41 extends into an
end wall of the chamber 10 and is centred on the longitudinal
central axis thereof; it can be plugged gradually by the shutter
from a shutter position in which this shutter is away from the seat
411 to a position in which it rests on the seat, and can be
gradually uncovered in the opposite direction.
[0050] At its opposite end to the end into which the first access
41 extends, the chamber has another access 44, also centred on the
longitudinal central axis of the chamber, and which is not
pluggable.
[0051] The housing 1 is designed to be fixed to a housing base 1'
to which the housing can be fixed by screws passing through
respective flanges of the housing 1 and of the base 1'; the chamber
10, the lateral wall of which is housed over at least part of its
length in the base 1', is therefore extended, beyond the said other
access 44, by a pipe 14 extending into the base 1' in the direction
of the longitudinal central axis of the chamber 10. An additional
access 43, which is also not pluggable, opens into the lateral wall
of this pipe 14.
[0052] The first access 41 is an orifice extending into the lateral
part of the wall of a pipe 11 formed in a single piece with the
housing and which extends in a radial direction with respect to the
chamber 10 on the other side of the shutter 2'.
[0053] To actuate the shutter 2' in terms of translation
selectively in one direction or the other along the extension of
the longitudinal central axis of the chamber 10, an actuator with a
motor 6 is fixed to the housing and more precisely to the lateral
wall of the pipe 11 opening into the chamber via the pluggable
access 41.
[0054] As this motor 6 and its coupling 7 connecting it to the plug
2' are, in this instance, identical to those of the embodiment
depicted in FIGS. 1 and 2, they will not be described again; put
simply, the control shaft 73 is fixed to the central region of a
shutter 2' instead of being fixed to the central region of the end
of a spool.
[0055] For this purpose, the shutter 2' comprises a central hole
into which the control shaft 73 is clipped.
[0056] This thermostatic device also furthermore comprises an
independent expanding-wax backup thermostatic element 8; to carry
this thermostatic element 8, the internal surface of the region of
the side wall of the chamber 10 which is near the access 44 which
opens into the pipe 14 of the base 1' has an annular groove 102
into which are clipped the ends of a bridge 85 extending
diametrically across the chamber and pierced with a central hole in
which the thermostatic element 8 is fixed.
[0057] As before, part of the thermostatic element 8, namely its
cup 80 containing the wax, is placed directly and held fixedly in
the pipe 14 extending into the base 1' and therefore into the
stream of fluid travelling through this pipe 14. As the way in
which the thermostatic element 8 is mounted is identical to the way
in the previously described embodiment, it will not be described
again.
[0058] Also, as in the previously described embodiment, a
temperature sensor 9 extending into the pipe 14 of the base 1' in
close proximity to the cup of the thermostatic element is carried
by the lateral wall of the pipe; this sensor in this instance is
approximately opposite the additional access 43; the function of
this sensor is identical to that of the sensor in the previous
embodiment.
[0059] Thus, the output shaft of the motor 6 is actuated in terms
of rotation in one direction or the other according to the
directions of the variations in temperature of the fluid in the
pipe 14 of the base 1' which are detected by the sensor 9 and, in
proportion with the difference between the detected temperature and
the setpoint temperature or according to some other algorithm,
moves the shutter 2' in translation in one direction or the other
via the reversible screw-nut system inelastic mechanical coupling
7.
[0060] In the event of a temperature rise, the movement of the
coupling 7 is a retraction which gradually causes the first access
41 to be uncovered; in the case of a drop in temperature, the
movement of the coupling 7 is an expansion which gradually causes
the first access 41 to be plugged.
[0061] Assuming that the motor 6, the sensor 9 or the computer or
any other element in the control sequence between the sensor and
the motor is experiencing a failure and the shutter 2' is thus not
actuated in translation in the direction for uncovering the first
access 41 even though it should have been, given the temperature of
the fluid, the moving part of the thermostatic element (that is to
say its piston) which also extends and retracts as the temperature
in the pipe 14 of the base 1' respectively rises and falls, takes
over from the motor 6 to actuate the shutter in terms of
translation as soon as the temperature of the stream of fluid
exceeds by a predetermined amount, for example by 5.degree. , the
temperature which should have caused actuation by the normal
actuating sequence involving the screw-nut system (FIG. 4). As the
coupling 7 is inelastic and the screw-nut support 71 is reversible,
the translational movement of the shutter 2' imparted to the
control shaft 73 causes, via the screw-nut system 71, a rotation of
the motor which, to within the amount of, in this instance,
5.degree. C., corresponds to the rotation that the motor should
have effected; the shutter 2' remains in the same position even if
the thermostatic element cools.
[0062] As the shutter 2' no longer closes, the regulation modes
prescribed by the computer no longer meet the requirements and
signals indicating failure can then be generated.
[0063] The value of the temperature threshold amount that triggers
the intervention of the thermostatic element 8 is determined by the
characteristics of the two sequences that actuate the shutter 2'
(the one involving the motor and the one involving the thermostatic
element) and also by the distance separating the free end of the
operating spindle 83 from that of the control shaft 73 under normal
operating conditions.
[0064] Various configurations are possible in a cooling circuit of
an internal combustion engine, for example for a vehicle.
[0065] In a first configuration, the internal combustion engine
outlet is connected to the inlet of a radiator and to the inlets of
various items of equipment such as a unit heater, a gearbox oil
heat exchanger and an engine oil heat exchanger, and the additional
access 43 is connected to the line connecting these elements; it is
therefore hot liquid inlet access. The first access 41 is connected
to the outlet of the radiator and is therefore a cold liquid inlet
access. The other access 44 is connected to the inlet of the engine
via a circulating pump and is therefore a hot or warm liquid outlet
access depending on whether or not the first access 41 is plugged
according to the computer algorithm. The unit heater and heat
exchanger outlets are also connected to a (different) inlet of the
circulating pump.
[0066] In a second configuration, the outlet of the internal
combustion engine is connected to the inlets of the unit heater and
of the exchangers, and to the additional access 43; it is therefore
hot liquid inlet access. The first access 41 is connected to the
inlet of the radiator and is therefore a hot liquid outlet access.
The other access 44 is connected to the inlet of the engine via the
pump and is therefore a hot liquid outlet; the outlet of the
radiator is connected to the same inlet of the pump to supply it
with cold liquid. The outlets of the unit heater and of the heat
exchanger are connected to another inlet of the pump. In this case
also, the thermostatic device does not itself act as a mixer, but
distributes the hot inlet fluid between the engine and the radiator
so that the engine receives cooling fluid at the appropriate
temperature.
[0067] In these two cases also, appropriate means make it possible
to check that the thermostatic device is "open" for cold-starting
the engine.
[0068] The thermostatic device depicted diagrammatically in FIG. 5
is a thermostatic valve with a flat shutter identical to the device
of FIGS. 3 and 4 except that it also allows a bypass function;
hence, only those of its components which are in addition to the
device of FIGS. 3 and 4 will be described, the common members being
identified in the figure using the same numerical references. In
this variation of the device of FIGS. 3 and 4, the base 1'
internally comprises, at the opposite end to its bearing face for
the housing 1 and beyond the sensor 9 and the additional access 43
when working away from this bearing face, a chamber 10' aligned
with the chamber 10 of the housing 1 and of larger cross section
than the internal region of the pipe 14 in which the lateral wall
of this chamber 10 is housed, so that it can connect to this region
via a shoulder. Furthermore, the cup 80 of the thermostatic element
8 is extended away from the piston 81 by a foot 86 to which is
fixed a bowl-shaped bypass sealing shutter 87 of larger cross
section than the internal region of the pipe 14 in which the
lateral wall of the chamber 10 of the housing 1 is housed and the
bottom of which is on the same side as the shoulder so that the
latter constitutes the seat 11' for the shutter 87. A bypass access
12' naturally opens into the chamber 10' of the base 1'. With this
setup, the bypass sealing shutter 87 is of course in the
widest-open position when the plug 2' is in the closed position,
and in the closed position when the sensor 9 detects a very high
temperature.
[0069] Of course, the invention is not restricted to the
embodiments described hereinabove and depicted and others may be
envisaged without departing from its scope, particularly
embodiments suited to other applications, for example in oil
circulation circuits or fuel circulation circuits for vehicles, or
alternatively heating circuits or any other application involving a
circuit through which there flows a fluid whose temperature is to
be regulated.
* * * * *