WO2008107788A1

WO2008107788A1 - Coolant circuit for a motor vehicle related degassing tank and motor vehicle

Info

Publication number: WO2008107788A1
Application number: PCT/IB2008/000549
Authority: WO
Inventors: Dominique Vaginet
Original assignee: Itw Bailly Comte
Priority date: 2007-03-08
Filing date: 2008-03-07
Publication date: 2008-09-12
Also published as: FR2913374A1; FR2913374B1

Abstract

The cooling circuit of the invention comprises a main conduit (BP) running in the vicinity of the vehicle passenger compartment (8), at least one secondary conduit (BS1 - BS3) and at least one flow regulator controlling the liquid flow in the circuit as a function of the liquid's temperature. Each flow regulator - which is fitted with a displaceable, shape memory alloy - is designed to implement at least one secondary conduit, a first fluid flow value related to a first range of temperatures and also a second flow value which is larger than the first and relating to a second range of temperatures higher the first range of temperatures.

Description

COOLANT CIRCUIT FOR A MOTOR VEHICLE RELATED DEGASSING TANK AND MOTOR VEHICLE

The present invention relates to motor-vehicle degassing tank, hereafter degassing chamber, related to such a cooling circuit, and to a motor vehicle fitted with such a cooling circuit.

Conventionally a cooling circuit is fitted with various conduits also called "Durites", running from the motor vehicle's engine and water pump, subtending different conduits.

A first conduit, herein called the invention's main conduit, runs near the motor vehicle passenger compartment to heat it. The cooling circuit also subtends different conduits, called secondary conduits herein. The latter include a conduit bypassing the main one at the thermostat and running toward the radiator, another connecting the radiator and the degassing chamber, and an additional conduit linking the thermostat and the degassing chamber.

When starting the vehicle, the liquid circulating in the cooling circuit must be heated in particular to raise the temperature of the passenger compartment. This operation entails obviously substantially a high fuel consumption.

Accordingly the objective of the present invention is a cooling circuit saving fuel during this vehicle startup relative to the solutions of the state of the art.

For that purpose the objective of the present invention is a cooling circuit fitted with at least one flow regulator driving the liquid flow in said circuit as a function of the coolant's temperature, each flow regulator comprising one displaceable element of which the main dimension varies with temperature, said element being made of a shape memory, the or each flow regulator being designed that there shall be — at least in one secondary conduit - a first liquid flow for a first range of temperatures, further a second liquid flow larger than the first for a second range of temperatures higher than the first.

Another objective of the present invention is a degassing chamber which is part of a cooling circuit such as defined above, said degassing chamber being fitted with an intake pipe hooked up to at least one secondary conduit of the cooling circuit, this intake pipe being fitted with at least one flow regulator to drive the liquid flow in this intake pipe as a function of its temperature, each flow regulator being fitted with a displaceable element of which the main dimension varies with temperature, this element being a shape memory alloy, the or each flow regulator being able to maintain in the intake pipe a first coolant flow value for a first range of temperatures and a second flow value larger than the first for a second range of temperatures higher than the first one.

Lastly another objective of the present invention is a motor vehicle fitted with a cooling circuit such as defined above.

The present invention is elucidated below in relation to the appended drawings of illustrative and non-limiting embodiment modes:

- Fig. 1 is a schematic of a motor vehicle cooling circuit of the present invention,

- Fig. 2 is a longitudinal section illustrating a degassing chamber of this cooling circuit,

- Fig. 3 is a plot of length vs temperature of a shape memory wire of the degassing chamber, - Figs. 4, 5 are longitudinal sections on a larger scale showing the two positions a flow regulator fitted with the shape memory wire in the degassing chamber of Fig. 2,

- Figs. 6, 7 are longitudinal sections showing two positions of a flow regulator of the invention of a first embodiment mode, and

- Figs. 8, 9 are longitudinal sections showing tow positions of a flow regulator of a further embodiment mode of the invention.

Fig. 1 shows a schematic cooling circuit of the invention. It contains the vehicle engine 2, its water pump 4 and the associated thermostat 6. This cooling circuit contains a number of different conduits (also called "Durites") conventionally subtending several conduits.

This circuit also includes a first so-called main conduit BP running from the thermostat 6 to the heater of the passenger compartment 8 and then is returned to the pump 4. There are also other, so-called secondary conduits, namely a first secondary conduit BSi running from the thermostat 6 to the radiator 10 and then returning to the water pump 4.

A second secondary conduit BS₂ runs from the conduit BSi directly below the radiator 10. This conduit BS₂ communicates with a degassing chamber 12, then with the water pump 4. Lastly a secondary conduit BS₃ connects the thermostat 6 to this degassing chamber 12.

The various above cited components are known per se and were succinctly described above.

Fig. 2 illustratively shows more closely the degassing chamber 12 which conventionally comprises a case 14 defining an (inside) volume V to which the access is through an aperture 16. A stub 18 which is part of the conduit BS₃ communicates with an intake pipe 20 of the chamber 12, said intake pipe in turn issuing into a stub 22 part of the secondary conduit BS₂. The intake pipe 20 is vertical and associated with a flow regulator 24 comprising a shape memory alloy wire 26. The composition of such a wire is conventional and illustratively may be nickel and titanium. The wire 26 and the intake pipe 20 are coaxial.

The first wire end 26i is firmly joined to the walls of the intake pipe 20 whereas its opposite end 26₂ supports a solid valve element 28. This element illustratively is conical and cooperates with a shoulder 30 of the intake pipe 22. Be it noted that the shoulder cross-section increases downstream, in this case downward in Fig. 2.

The characteristics of the shape memory wire 26 are sketched in Fig.

3 showing the wire length I vs. the temperature T.

Accordingly at low temperature, namely for a cold engine, this wire exhibits a first length U. Then, as the temperature increases, the wire length at first remains substantially constant before abruptly rising as the temperature exceeds a first characteristic value Ti. At that time the wire length is b, substantially larger than the above cited length I₁, and then stabilizes at this value I₂ when the temperature continues rising. The changes in wire length during temperature increase are shown by the solid line I.

It is assumed that next the temperature drops from a value larger than

Ti. Under these conditions the wire length is substantially constant until the temperature has dropped to T₂ less than T-i; at T₂ the wire length abruptly drops to resume its initial value I₁. Subsequent temperature decrease does not significantly affect the wire length. The changes in wire length during temperature decreases are shown by the dashed curve II.

Illustratively but without implying limitation, T₁ is between 50 and 90 ⁰C, in particular about 70 ⁰C, and T₂ is between 30 and 70 ⁰C₁ in particular about 50 ⁰C. Moreover the ratio I₂ZI₁ illustratively is between 1.03 and 1.06, in particular being about 1.05. As shown by Fig. 3, the wire 26 exhibits solely two stable positions, namely two lengths values, depending on the temperature it assumes. These two stable positions apply on either side of a single threshold, whether during a temperature increase or a temperature decrease. However said two thresholds are different, namely being respectively Ti and T₂ depending on the wire being heated or cooled.

The geometry of the degassing chamber was cited in relation to Fig. 2 and is further elucidated as follows in relation to Figs. 4 and 5.

As shown by these Figures, the shoulder 30 is bounded by two zones 32 and 34 of the intake piper 20 having respective cross-sections d and D.

The cross-section of the cone 28 is hardly less than the diameter d but substantially less than the diameter D.

Be it assumed that initially the engine is cold, namely that the liquid temperature inside the intake pipe 20 is less than the first temperature Ti of the wire 26. Accordingly the length of this wire is h, and as a result the cone

28 is opposite the narrow part 32, defining an annular passageway P1 of narrow cross-section (Fig. 4). Under these conditions the possible liquid flow Di is comparatively slight.

As the engine keeps running, its temperature rises and commensurately heats liquid in the cooling circuit. When this temperature exceeds the value T-i, the length of the wire 26 increases from its initial value

I₁ to the higher value I₂. As a result the cone 28 henceforth subtends an annular passage P₂ with the wide zone 34, said passage's cross-section being much larger than that of the initial passage P-i. Accordingly the liquid flow D₂ is also much larger than the first cited flow Di.

As a result the regulator element 24 is flow-regulating, namely, within a first and relatively low temperature range, the liquid is able to flow relatively slightly in the intake pipe 20 and hence in the conduits 18 and 22. As regards a higher temperature range, on the other hand, this liquid flow in the conduits 18 and 22 and in the intake pipe 20 is substantially higher.

Figs. 6 and 7 illustrate an embodiment variation of the present invention that may be in addition or an alternative to that of Figs. 2, 4 and 5.

A flow regulator 124 similar to 24 as described above is configured inside a "Durite" conduit of either of the secondary conduits. It is assumed in this embodiment variation that the regulator element 124 is implanted in a Durite conduit 36 with which the conduit BS₁ is fitted. Said Durite conduit defines a shoulder 38 of which the cross-section flares in the downstream direction. The shape memory wire 126 is coaxial with this Durite conduit 36.

In a manner such as already previously described, the regulator element 124 assumes exclusively two stable positions which depend on the temperature of the liquid flowing in the Durite conduit 36. As a result and as shown in Fig. 6, when the temperature is fairly low, in particular less than T-i, the shape memory wire 126 exhibits a reduced length so that the cone 128 is opposite the narrow part of the shoulder 38. Consequently the allowed liquid flow also is fairly low.

On the other hand, when the temperature rises above T₁, the wire 126 elongates whereby the cone 128 henceforth shall be opposite the widest part of the shoulder 38. In this manner the flow of liquid in the Durite conduit 36 is substantially increased.

Figs. 8 and 9 illustrate another variation of the invention, which may be additional, or alternative to either of the two other preceding embodiment modes.

In this third variation of the present invention, a bypass 42 connects the conduit 18 of the secondary conduit BS₃ with the conduit 40 of the main loop BP. This bypass 42 allows moving the fluid in a single direction, but solely from the conduit 18 toward the conduit 40. This bypass 42 is fitted with a shoulder 44 of which cross-sectionally tapers downstream, namely toward the conduit 40 of the main loop. This circuit also comprises a flow regulator 224 similar to the flow regulators 24 and 124 of the preceding Figures wherein the cone is replaced by a ball 228. The wire 226 of the regulator element 224 is coaxial with the tubular bypass

42.

Accordingly the wire 226 and the ball 228 are able to assume solely two stable positions depending the liquid's temperature. At low temperature (Fig. 8), the wire length is reduced, as a result of which the ball center aligned with the widest part of the shoulder 44, allowing a large liquid flow from the secondary conduit BS₃ to the main conduit BP. In other words, the liquid flow in the BS₃ conduit is much reduced downstream of the bypass 42.

On the other hand, at a higher temperature (Fig. 9), the wire 226 is elongated, as a result of which the ball 228 is now situated by its center level with the narrow part of the shoulder 44. Therefore the liquid flow to the main conduit BP is reduced. As a result the liquid flow in the conduit BS₃ downstream of the bypass 42 is reduced only slightly.

In the diverse above discussed embodiment modes of the present invention, the cooling circuit is fitted with at least one flow regulator 24, 124 or 224 that may assume only two temperature-dependent positions. At low temperatures, this flow regulator subtends a constriction in the first and second embodiment modes, or else, in the third embodiment mode, it subtends a larger cross-sectional zone. On the other hand, at high temperatures, this flow regulator subtends a large passageway in the first and second embodiment modes or else constitutes a constriction in the third.

Consequently, in the present invention, the liquid flow in at least one secondary conduit is less at low temperatures than that prevailing at high temperatures. Also, regardless of which temperature range is involved, the flow is substantially constant in the main conduit. The present invention consumes substantially the same energy content to heat the liquid of the cooling circuit as does the prior art. However it must be borne in mind that in the state of the art, said energy content is distributed substantially homogeneously to heat the main conduit and the different secondary conduits. In the invention, however, part of this energy content is used in a first stage to heat the liquid in the main conduit, considering that the flow is much less in the secondary conduits.

Under these conditions, thanks to carrying out the present invention, the vehicle engine temperature rises much more rapidly than in the state of the art. At the same time engine oil also is heated more rapidly, thereby saving the time the cold oil must be agitated initially. As a result engine efficiency is improved over the state of the art and energy consumption is reduced.

Be it also borne in mind that a shape memory wire is advantageously used because being simple, reliable, and economic. When the temperature rises, such a wire also allows returning the flow liquid at its typical values to the secondary conduits. Lastly and in this respect, merely by using a shape memory wire that is restricted to exhibit solely two positions is advantageous with respect to simplicity and satisfactory operation.

Claims

1. A motor-vehicle cooling circuit comprising different conduits running from this engine, namely a main conduit (BP) running in the vicinity of the vehicle passenger compartment (8), also at least one secondary conduit (BSi-BS₃), characterized in that this cooling circuit is fitted with at least one flow regulator (24; 124; 224) to vary the liquid flow in said circuit depending on the liquid's temperature, each flow regulator comprising a displaceable element (26; 126; 226) of which the main dimension (I) varies depending on temperature, said displaceable element being made of a shape memory alloy, the or each flow regulator implementing, in at least one secondary conduit, a first liquid flow value (Di) for a first temperature range and a second flow value (D₂) larger than the first, and related to a second temperature range higher than the first.

2. Cooling circuit as claimed in claim 1 , characterized in that it comprises a flow regulator (24) in an intake pipe (20) which is part of a degassing chamber (12) communicating with at least one secondary conduit.

3. Cooling circuit as claimed in either of claims 1 and 2, characterized in that it comprises a flow regulator (124) in at least one conduit (36) which is part of a secondary conduit (BS-i).

4. Cooling circuit as claimed in any of the above claims, characterized it comprises a flow regulator (224) in a bypass (42) allowing liquid flow in a secondary conduit (BS₃) toward the main conduit (BP).

5. Cooling circuit as claimed in any of the above claims, characterized in that the displaceable shape memory alloy element (26; 126; 226) comprises a first end (26i) solidly joined to a liquid flow wall and a second end (26₂) of which the position may vary relative to the first end, said second end supporting a solid structure (28) cooperating with two adjacent zones (32, 34) of different cross-sections configured on either side of a shoulder (30; 38; 44) constituted by said wall.

6. Cooling circuit as claimed in any of the preceding claims, characterized in that the displaceable element (26; 126; 226) may assume solely two stable temperature dependent positions.

7. Cooling circuit as claimed in the preceding claim, characterized in that, in a first stable position, the displaceable element (16; 126; 226) exhibits a first length (l-i) within a first range of temperatures, the length of this displaceable element increasing up to a second length (b) corresponding to a second stable position when transiting from said first range of temperatures to said second range of temperatures which is situated above a predetermined temperature (Ti).

8. Cooling circuit as claimed in claim 7, characterized in that the predetermined temperature (Ti) is between 50 and 90 ⁰C, in particular about 70 ⁰C.

9. Cooling circuit as claimed in either of claims 7 and 8, characterized in that the ratio (I₂/Ii) of the second to the first lengths is between 1.03 and 1.06, preferably about 1.05.

10. Cooling circuit as claimed in either of claims 2 and 3, combined with claim 5, characterized in that the solid structure (28; 128) subtends, together with said wall, a first liquid passageway cross-section (P₁) for the first range of temperatures which is substantially less than a second liquid passageway cross-section (P₂) subtended by the said solid element and said wall within the second range of temperatures.

11. Cooling circuit as claimed in either of claims 4 and 5, characterized in that the solid structure (228), subtends with said wall a first liquid passageway cross-section for the first range of temperatures which is substantially larger than a second liquid passageway cross-section defined by the solid structure and said wall within the second range of temperatures.

12. Cooling circuit as claimed in any of the above claims, characterized in that the displaceable element (26; 126; 226) is a shape memory alloy wire.

13. Cooling circuit as claimed in claim 12, characterized in that the shape memory alloy wire (26; 126; 226) is configured within an intake pipe (20; 36; 42) of the cooling circuit, said wire and intake pipe being coaxial.

14. A degassing chamber which is a component of a cooling circuit as claimed in claim 2, this degassing chamber (12) being fitted with a intake pipe (20) that shall be connected to at least one secondary conduit (BS₂, BS₃) of the cooling circuit, said intake pipe being fitted with at least one flow regulator (24) controlling the liquid flow circulating in said intake pipe as a function of the liquid's temperature, each flow regulator comprising a displaceable element (26) of which the main dimension varies with temperature, said displaceable element being made of a shape memory alloy, the or each flow regulator being designed to adjust, in the intake pipe (20), a first flow value (D₁) for a first range of temperatures and a second flow value (D₂) which is larger than the first flow value (Di) which applies within a second range of temperatures higher than the first.

15. A motor vehicle fitted with a cooling circuit as claimed in one of claims 1 through 13.