WO2004008049A1

WO2004008049A1 - Expansion member for a motor vehicle air-conditioning unit cooling circuit

Info

Publication number: WO2004008049A1
Application number: PCT/FR2003/002073
Authority: WO
Inventors: Mohamed Ben Yahia; Jean-Charles Ropers
Original assignee: Valeo Climatisation
Priority date: 2002-07-08
Filing date: 2003-07-04
Publication date: 2004-01-22
Also published as: AU2003267509A1; FR2841829B1; FR2841829A1

Abstract

The invention concerns an expansion member (40) for a motor vehicle air-conditioning unit (1) comprising a hollow tube (42) mobile in translation inside a ring (41), a peripheral orifice (45) arranged in said ring (41) and provided with a fluid inlet (45a) and outlet (45b), a member for closing (46) the peripheral orifice (45) adapted to shift from a first position wherein it closes the peripheral orifice (45) to a second position wherein it allows the cooling fluid through the peripheral orifice (45), and a compression spring (44) pressed against the ring (41) and a radial stop (43) fixed around the hollow tube (42), said spring (44) having an elastic return force (R) for maintaining the closure member (46) in its first closed position. In said expansion member (40), the closure member (46) is arranged on the side of the cooling fluid outlet (45b) and shifts from the first position to the second position when the pressure of the cooling fluid exerted directly thereon is greater than the elastic return force (R) of the spring (44).

Description

RELIEF MEMBER FOR COOLING CIRCUIT OF A MOTOR VEHICLE AIR CONDITIONING APPARATUS

The invention relates to an expansion device for the cooling circuit of a motor vehicle air conditioning device. . The air conditioning devices usually used in motor vehicles generally include a cooling loop composed of at least: a compressor driven by the heat engine, a condenser, an expansion device and an evaporator through which l air powered by a blower. The compressor, the expansion member, the condenser and the evaporator are typically interconnected by pipes for circulation of a cooling fluid, also called refrigerant. Depending on the exterior and / or interior temperatures of the passenger compartment of the vehicle as well as the engine speed (engine idling or vehicle in motion), the fresh air requirements are different to cool the passenger compartment. The various mechanical components of the system, and in particular the compressor and the condenser, therefore operate differently depending on the temperature and operating conditions in order to cool the air in the passenger compartment in an optimized manner.

Thus, when the engine is idling, the compressor is running at low speed and therefore it cannot supply the condenser with coolant at sufficient pressure. As a result, the condenser, then the evaporator, malfunctions and the cooling of the passenger compartment is less efficient. When the vehicle is in motion, the compressor runs faster and can therefore compress the coolant to a higher pressure. The condenser and the evaporator then work more efficiently to cool the passenger compartment. For example, at idle, the fluid is under a pressure of 4 bars at a temperature of 8 ° C while, at normal vehicle speed, the fluid pressure is 3 bars at a temperature of 0 ° C , the cooling efficiency being higher in the latter case.

In an attempt to resolve this problem, patent No. US 5,081,847 proposes an air conditioning device for a motor vehicle in which the expansion member has a variable orifice, that is to say it has a main central orifice always open regardless of the pressure of the coolant passing through it, and at least one additional peripheral orifice opening or closing depending on the pressure of said fluid cooling to adapt to the power supplied to the compressor to optimize the cooling of the passenger compartment. This expansion member has, in particular, a central channel provided with a compression spring and two discs opposing the pressure of the fluid and opening or not the second orifice for the passage of said fluid depending on the pressure of the fluid .

This device has two distinct operating modes depending on the configuration of the shutter discs and the expected result.

In a first operating mode, when the engine is idling and the car is stopped, the compressor cannot supply a large flow of pressurized fluid. It therefore supplies a fluid under high pressure to compensate for the ineffectiveness of the condenser traversed by a low flow of air. When the pressure of the cooling fluid passing through the expansion member is greater than the restoring force of the compression spring, only the main orifice is open to maintain or increase the pressure of the cooling fluid. On the other hand, when the vehicle is in movement, the compressor can provide a higher flow of pressurized fluid. As the condenser is more efficient because it is traversed by a large air flow, the fluid pressure decreases at the outlet of the condenser. In this case, when the pressure of the coolant is lower than the return force of the spring, the two orifices are open to provide a greater flow of coolant to the evaporator.

In the second mode of operation, the opposite occurs. When the pressure of the coolant is greater than the restoring force of the compression spring, the two orifices are opened to provide a greater flow of fluid to the evaporator which compensates for the ineffectiveness of the condenser. On the contrary, when the pressure of the coolant is lower than the return force of the spring, only the main orifice is open to send a weaker flow of coolant towards the evaporator. In these two independent operating modes, it is thus possible to optimize the cooling by playing on the flow / pressure couple at the outlet of the expansion member, and this thanks to the opening or not of a peripheral orifice.

However, this expansion member has drawbacks. Indeed, it is complex to produce and has a low reactivity to fluid pressure which causes leaks and an extended response time.

To solve these problems, the invention proposes that a shutter be placed in a particular zone of the expansion member, in particular with respect to the peripheral orifice, and that the pressure of the fluid which makes it possible to pass the he expansion member from one position to another is exerted directly on this shutter which therefore controls the change of position quickly and precisely.

More specifically, the subject of the invention is an expansion member for a coolant transport circuit of a vehicle air conditioning device, said expansion member comprising at least:

- a hollow tube placed inside a centering ring and having a central orifice for the passage of the coolant which is constantly open, - an orifice provided in said centering ring peripherally to the hollow tube and provided with an inlet and a coolant outlet,

a shutter member for the peripheral orifice fixed around the hollow tube and adapted to pass, according to the pressure of the cooling fluid and by axial translation of said tube, from a first closed position in which said shutter member blocks peripheral orifice, to a second open position in which said obturation member lets the coolant pass through the peripheral orifice, expansion member in which the obturator is disposed at the outlet of the coolant of the peripheral orifice and is moved from the first closed position to the second open position when the pressure of the cooling fluid which is exerted directly on said closure member is greater than the elastic return force of the spring. According to preferred embodiments of the invention: - the hollow tube is mounted movable in translation inside the centering ring and the expansion member further comprises a compression spring bearing on the one hand against the centering ring and on the other hand against a radial stop fixed around the hollow tube, on the side of the coolant inlet of the peripheral orifice, said spring having an elastic return force making it possible to maintain the obturation in its first closed position, - The hollow tube is rotatably mounted relative to the centering ring and rotates about its axis to pass the shutter member from the first closed position to the second open position;

the obturator has an external shape chosen from a substantially spherical, substantially conical, and disc shape extending perpendicular to the hollow tube,

According to other particular embodiments,

- the shutter member is an articulated valve opening when the pressure of the cooling fluid exerted on the shutter member is greater than the elastic return force of the spring;

- The expansion member further comprises at least a second peripheral orifice for the passage of the cooling fluid to more precisely modulate the reactivity of the expansion member to the pressure of the fluid; - The second peripheral orifice is disposed substantially symmetrically with the first peripheral orifice relative to the axis of the tube and it has a passage section smaller than the passage section of the first peripheral orifice;

- Each peripheral orifice is closed by an independent shutter;

the pressure of the cooling fluid which triggers the opening of the shutter member of the first peripheral orifice is lower than the pressure of the cooling fluid which triggers the opening of the shutter member of the second peripheral orifice; the expansion member also comprises a valve with constant pressure drop upstream from the orifices for passage of the cooling fluid,

- The expansion member is mounted in a clamp for fixing the coolant transport circuit. The invention also relates to an air conditioning device for a motor vehicle comprising at least, in a circulation loop of a cooling fluid, an evaporator, a compressor, a condenser, and an expansion member as defined above.

Other characteristics, details and advantages of the invention will emerge on ^* reading the description given with reference to the attached drawings given by way of example which represent respectively: FIG. 1, a schematic view of a motor vehicle air conditioning device comprising an expansion member,

FIG. 2, a sectional view of a first embodiment of the expansion member according to the invention in a first operating position,

FIG. 3, a view similar to FIG. 2 in which the expansion member is in a second operating position,

- Figure 4, a sectional view of a second embodiment of the expansion member according to the invention, - Figure 5, a sectional view of a third embodiment of the expansion member according to the invention,

FIG. 6, a sectional view of a fourth embodiment of the expansion member according to the invention,

- Figure 7, a sectional view of a fifth embodiment of the expansion member according to the invention

FIG. 8, a view similar to FIG. 7 in which the expansion member is in a second operating position,

- Figure 9, a sectional view of a sixth embodiment of the expansion member according to the invention - Figure 10, a sectional view along line AA of the figure

9

FIG. 11, a sectional view of a seventh embodiment of the expansion member according to the invention, and

- Figure 12, a comparative graph of the pressure of the fluid as a function of the flow rate of the cooling fluid for an expansion member of the prior art and for the expansion member of the invention.

Figure 1 schematically shows an air conditioning unit 1 for a motor vehicle intended to cool the passenger compartment. This device 1 forms a circuit 2 inside which circulates in a closed loop a cooling fluid of the chlorofluorocarbon (CFC) type or a hydrofluorocarbon (HFC) such as R134A. The air conditioning apparatus 1 comprises in particular an evaporator 10 traversed by pulsed air which is cooled before being distributed in the passenger compartment, a compressor 20 supplied with energy by the combustion engine of the vehicle, a condenser 30 traversed by outside air and an expansion member 40, or valve, according to the invention. The coolant circulates inside, from this circuit 2 to different pressures and different temperatures depending on where it is located and follows a thermal cycle with indirect heat exchange with the outside.

Figure 2 shows the expansion member 40 seen in longitudinal section. The direction of circulation of the cooling fluid coming from the condenser towards the evaporator is indicated by the arrows F.

This expansion member comprises a ring 41 set in the

^• circuit 2. A hollow tube 42 is mounted inside the ring and 41 can slide axially. This hollow tube 42 has a central orifice 42a for the passage of the cooling fluid. A stop 43 is mounted at one end of the tube 42. A compression spring 44, having an elastic return force R depending on its stiffness coefficient, is supported between a radial surface 43a of the stop 43 and a radial surface 41a of the ring 41.

A peripheral orifice 45 for the passage of the cooling fluid is also arranged through the ring 41, substantially parallel to the central orifice 42a. This orifice 45, typically a through bore, has a fluid inlet 45a and a fluid outlet 45b. The stop 43 and the compression spring 44 are arranged on the side of the fluid inlet.

A shutter member 46, of substantially spherical external shape, is fixed around the hollow tube 42, substantially at the other end of the latter, that is to say on the side of the fluid outlet 45b. This shutter member 46 is adapted to pass from a first closed position in which it blocks the peripheral orifice 45, as illustrated in FIG. 2, towards a second open position in which it lets the coolant pass through. the peripheral orifice 45, as illustrated in FIG. 3.

For this, as soon as the pressure of the cooling fluid exerted on the shutter 46 exceeds a certain threshold equivalent to the force of> return R of the compression spring 44, the shutter 46 moves in the direction of circulation of the fluid (arrow F), compresses the spring 44 and opens the peripheral orifice 45. The cooling fluid can then pass both through the central orifice 42a according to arrow F1, and also through the peripheral orifice 45 according to arrow F2 of the figure 3.

FIG. 4 represents an alternative embodiment in which the axial displacement of the hollow tube 42 carrying the shutter 46 is produced by rotation of said tube 42 about its axis, as illustrated by the arrow T. For this, an outer part of the tube 42, located between the compression spring 44 and the shutter 46, is provided with a thread 47, while an inner part of the ring 41 has a thread 48 cooperating with the thread 47. When the pressure of the cooling fluid exerted on the shutter 46 is greater than the restoring force R of the compression spring 44, this causes rotation of the tube 42 in the ring 41, that is to say that is to say a translation of said tube, and therefore the compression of the spring 44 and the opening of the secondary orifice 45 allowing the passage of the fluid in the direction of the evaporator 10. FIGS. 5 and 6 are alternative embodiments of the figure

2. In FIG. 5, the shutter 46 has a substantially conical shape flaring out from the hollow tube 42, and in FIG. 6, the shutter 46 has a shape of disc or washer extending radially.

Figures 7 to 11 show embodiments of the expansion member 40 according to the invention in which the hollow tube 42 is movable and the expansion member 40 is devoid of compression spring and stop.

Figures 7 and 8 show a fifth embodiment of the shutter 46 which is then presented as a return valve 50 articulated on the hollow tube 22 and reacting to the pressure of the cooling fluid according to a calibration determined for example by a spring torsional with a certain stiffness. Thus, in FIG. 7, the pressure of the cooling fluid which is exerted on the active surface of the valve 50 being less than the setting of the valve 50, that is to say the stiffness of the spring which it contains, l the peripheral orifice remains closed and the fluid only passes through the central orifice 42a. On the other hand, in FIG. 8, the pressure of the cooling fluid which is exerted on the active surface of the valve 50 being greater than the setting of said valve, the latter opens and the fluid can thus pass through the central orifice 42a and the peripheral orifice 45, as illustrated respectively by the arrows F1 and F2.

FIG. 9 illustrates a sixth embodiment of the expansion member 40 in which peripheral orifices 45 and 55 are provided and is typically in the form of two through bores arranged diametrically opposite one relative to the other and having, different passage sections. For example, the second peripheral orifice 55 has a passage section smaller than the passage section of the first peripheral orifice 45, as illustrated in FIG. 10. Two shutters 46 and 56 are also provided for closing these peripheral orifices and are in the form of hinged valves 50 and 60 with return similar to that of FIGS. 7 and 8, c 'is to say provided for example with spring _. tared twist.

The calibration of the two valves 50 and 60 is such that they do not operate for the same fluid pressure. Thus, for a pressure exerted on the valves less than their respective calibration, the cooling fluid only passes through the central orifice 42a. For a coolant pressure slightly higher than the setting of the valve 50, the cooling fluid passes through the central orifice 42a and through the first peripheral orifice 45. Finally, for a coolant pressure higher than the setting of the second valve 60 , the fluid passes through the central orifice 42a, through the first peripheral orifice 45 and through the second peripheral orifice 55.

In the alternative embodiment of FIG. 11, the two valves are replaced by a single valve 50 in two parts, each having a different calibration.

Advantageously, in the various embodiments presented, a valve with constant pressure drop (not shown) of known type is installed upstream of the orifices of the expansion member in order to avoid the possible overflow provided by the expansion member to the evaporator, which saves energy during the production of cold.

The comparative graph shown in FIG. 12 illustrates the mode of operation of the expansion member 40 with variable orifice as described above (curve (A)), in comparison with that of a member with fixed orifice of the prior art (curve (B)). Curve (C) is established by difference between the values of the other two curves.

Thus, for a coolant pressure of around 10.25 bars, the flow rate of the coolant is around 90 kg / h in the case of an expansion device of the prior art with a fixed orifice, while the fluid flow rate is around 55 kg / h in the case of the expansion member 40 according to the invention with variable orifice. ..

When the fluid pressure increases due to the high thermal load required (consequence of a high external temperature and / or low temperature required in the passenger compartment), for example up to 14.5 bars, each peripheral orifice of the expansion member 40 according to the invention begins to open gradually, so that the flow of cooling fluid increases until it reaches substantially the same value as that reached in the case of an expansion device of the prior art, that is to say here about 145 kg / h.

Thus, the solution of the invention makes it possible to better adapt the flow delivered as a function of demand and to avoid the blows of cooling fluid caused by the entry of said fluid in liquid phase inside the compressor, which could lead to deterioration or even destruction of said compressor.

The expansion member 40 can be integrated in a fixing flange (not shown) such as those usually used in the cooling circuits of vehicle air conditioning devices. Machining operations (in particular bores) are carried out in this flange in order to accommodate the expansion member 40, which saves space, fewer parts to be produced and better integration of the expansion member in the device . By way of example, said flange can constitute the fixed parts of the expansion member, that is to say both the centering ring 41 and the external tube (not referenced) of FIG. 2. It must It should be understood, however, that these examples are given solely by way of illustration of the subject of the invention of which they do not in any way constitute a limitation. Thus, the compression spring can work in extension in another arrangement. The articulated valves can open depending on the pressure of the coolant, or close according to their arrangement. The number of peripheral orifices can vary according to the needs in order to produce an expansion member with multiple adjustments as a function of the pressure of the fluid.

Claims

1. Expansion member (40) for circuit (2) for transporting cooling fluid of a vehicle air conditioning apparatus (1), said expansion member (40) comprising at least:

a hollow tube (42) placed inside a centering ring (41) and having a central orifice (42a) for the passage of the cooling fluid which is constantly open,

- an orifice (45) arranged in said centering ring (41) peripherally to the hollow tube (42) and provided with an inlet (45a) and an outlet

(45b) of coolant,

- A shutter member (46) of the peripheral orifice (45) fixed around the hollow tube (42) and adapted to pass, depending on the pressure of the cooling fluid and by axial translation of said tube (42), of a first closed position in which said shutter member (46) blocks the peripheral orifice (45), towards a second open position in which said shutter member (46) lets coolant pass through the peripheral orifice (45), characterized in that the closure member (46) is disposed on the side of the outlet of the cooling fluid (45b) from the peripheral orifice (45) and in that it passes from the first position closed to the second open position when the pressure of the cooling fluid which is exerted directly on said closure member (46) is greater than the elastic return force (R) of the spring (44).

2. detent member according to claim 1, characterized in that the hollow tube (42) is mounted movable in translation inside the centering ring (41) and in that said detent member (40) comprises in addition to a compression spring (44) bearing on the one hand against the centering ring (41) and on the other hand against a radial stop (43) fixed around the hollow tube (42), on the inlet side ( 45a) of fluid for cooling the peripheral orifice, said spring (44) having an elastic return force (R) making it possible to maintain the shutter member (46) in its first closed position,

3. Expansion member according to claim 1 or 2, wherein the hollow tube (42) is rotatably mounted relative to the centering ring (41) and is adapted to rotate around its axis to pass the member shutter (46) from the first closed position to the second open position.

4. Expansion device according to any one of the preceding claims, in which the shutter (46) has a substantially spherical external shape.

5. Expansion member according to any one of claims 1 to 3, wherein the shutter (46) has a substantially conical outer shape.

6. Expansion member according to any one of claims 1 to 3, wherein the shutter (46) has a disc shape extending perpendicular to the hollow tube (42).

7. Expansion member according to claim 1, wherein the shutter member (46) is an articulated valve (50) opening when the pressure of the coolant acting on the shutter (46) is greater to the elastic return force (R) of the spring (44).

8. Expansion member according to claim 7, characterized in that it further comprises at least a second peripheral orifice (55) for the passage of the cooling fluid.

9. expansion device according to claim 8, in which the second peripheral orifice (55) is disposed substantially symmetrically with the first peripheral orifice (45) relative to the axis of the tube (42), and in that said second peripheral orifice (55) has a passage section smaller than the passage section of the first peripheral orifice (45).

10. Expansion member according to claim 8 or 9, wherein each peripheral orifice (45, 55) is closed by an independent shutter (46, 56).

11. Expansion device according to claim 10, in which the pressure of cooling fluid which triggers the opening of the shutter member (46) of the first peripheral orifice (45) is lower than the pressure of the cooling fluid which triggers the opening of the shutter member (56) of the second peripheral orifice (55).

12. Expansion member according to any one of the preceding claims, characterized in that it further comprises a valve with constant pressure drop upstream of the coolant passage orifices.

13. Expansion device according to any one of the preceding claims, characterized in that it is mounted in a fixing flange of the circuit (2) for transporting the coolant.

14. Air conditioning apparatus (1) for a motor vehicle comprising at least, in a circulation loop (2) of a cooling fluid, an evaporator (10), a compressor (20), a condenser (30), and a detent member (40) according to any one of the preceding claims.