FR3025270A1 - CIRCULATING AIR FLOW CLUTCH CLUTCH AND COOLING THROUGH INTERNAL COOLING MEANS - Google Patents

Abstract

A clutch (EM) comprises a housing (CE) housing a flywheel (VM), adapted to be secured to a shaft (AM) of a heat engine, at least one friction disk (DF), adapted to be secured to a primary shaft (AP) of a gearbox, and a pressure mechanism (MP) comprising at least one pressure plate (PP) adapted to press the friction disc (DF) against the flywheel (VM), a cover (CV) fixedly secured to the flywheel (VM) and housing the pressure plate (PP), the first openings (01) for the air inlet, and peripheral openings (OP) for the output of this air. This casing (CE) also houses, on an inner face (FI) and on the path of the air downstream of the peripheral openings (OP), cooling means (MR) containing a heat transfer fluid capable of capturing contained calories. in this air to cool it.

Description

FIELD OF THE INVENTION The invention relates to clutches, and more specifically to the cooling of these clutches. BACKGROUND OF THE INVENTION A clutch is a mechanical system providing a coupling between a heat engine and a gearbox (mechanical or driven). It comprises for this purpose a flywheel, at least one friction disc, and a pressure mechanism (comprising at least one pressure plate and a cover, and a possible diaphragm). The flywheel (which can be single or double (primary and secondary)) is intended to be secured (in rotation but in free translation) to a shaft of the engine, for example its crankshaft. The friction disk is intended to be secured to a primary shaft of the gearbox. The pressure plate (of the pressure mechanism) is responsible for pressing the friction disk against the flywheel when it is pushed by a member such as a diaphragm under the action of a stop, itself actuated by a clutch control. The cover (of the pressure mechanism) makes it possible to firmly secure the latter to the flywheel. The pressure mechanism comprises in its lid and / or in its possible diaphragm first openings for the entry of air and peripheral openings for the output of this air in the vicinity of the flywheel / cover junction. The torque that is produced by the heat engine is first transmitted to the flywheel via the crankshaft (through its rotational movement), then to the friction disk and finally to the primary shaft of the gearbox. As known to those skilled in the art, in certain life situations, the increase in temperature of the clutch parts that are involved in the friction (pressure mechanism, flywheel and friction disc) may exceed a threshold beyond which there is a degradation of the torque transmission, or even deterioration or breakage of some parts. In order to partially overcome this disadvantage, thermal protection strategies have been proposed, particularly in the field of vehicles (generally automotive type). These strategies are integrated either in software or in the computer supervising the engine (and generally called "Multifunction Motor Control" (or CMM)) when the gearbox is of the manual type or in the gearbox actuator. when the latter is controlled, and generally take into account the measurement of the temperature of the pressure plate, which is continuously estimated throughout the life of the vehicle. When certain temperature thresholds are reached, protections are put in place, for example by activating the motor-fan unit and / or modifying the depression mapping of the accelerator pedal, in an attempt to reduce the temperature of the plateau of pressure.

This solution temporarily prolongs misuse of the clutch and thus slightly reduce the temperature of the air inside the housing. But as soon as the strategy is no longer used the temperatures of the different friction parts and the air inside the clutch housing start to grow very quickly.

It has also been proposed to cool the pressure plate by exchange with a heat transfer fluid flowing in the immediate vicinity of the latter. But this solution does not allow to cool the other parts involved in the friction, so that the temperature of the indoor air increases rapidly and finally the heat transfer fluid is no longer able to sufficiently cool the pressure plate. The cooling difficulties mentioned above are all the more problematic when it is desired to obtain an extension of gear ratios, especially in order to reduce energy consumption (and therefore the production of CO2 ). Indeed, the lengthening of these ratios leads to greater stress on the clutch, which requires strengthening of its parts and an adaptation of the forms of the latter that it is increasingly difficult to obtain.

The purpose of the invention is, in particular, to improve the situation. It proposes in particular for this purpose a clutch comprising a housing housing: - a clean flywheel to be secured to a shaft of a heat engine, 5 - at least a friction disc clean to be secured to a primary shaft of a box and a pressure mechanism comprising at least one pressure plate, suitable for pressing the friction disc against the flywheel, a cover secured to the flywheel and housing the pressure plate, the first 10 openings for the air inlet, and peripheral openings for the output of this air. This clutch is characterized by the fact that its housing also houses, on an inner face and on the path of the air downstream of the peripheral openings, cooling means which contain a heat transfer fluid capable of capturing the calories contained in this air to cool the latter. Thanks to the cooling of the air flowing inside the casing, it is now possible to obtain effectively and significantly a reduction in the temperature of the parts involved in the friction, which is likely to substantially increase the reliability and reliability. durability of the clutch. The clutch according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular: its cooling means can be arranged to be supplied with circulating heat transfer fluid, by an external cooling circuit; Its cooling means may comprise at least one heat exchanger of the air / heat transfer fluid type; at least one heat exchanger of the air / heat transfer fluid type may be installed on a downstream part of the internal face of the casing, intended to be situated in the vicinity of the gearbox; A heat exchanger of the air / heat transfer fluid type may be installed on a peripheral part of the inner face of the casing which is situated opposite the peripheral openings; - its cooling means may comprise at least one channel defined in a peripheral portion of the inner face of the housing which is located opposite the peripheral openings and containing at least the heat transfer fluid; The channel may comprise an input and an output intended to be coupled respectively to auxiliary and auxiliary outputs of the external cooling circuit; - Alternatively, the channel may be non-opening and may include a sealed subpart containing a heat-transfer product, and adapted to be surrounded by the coolant so that a portion of the calories transferred into the coolant can be captured by the heat transfer product to cool it; the heat-transfer product may be chosen from at least sodium, lithium and potassium. It may also comprise control means arranged to control the amount of heat transfer fluid which supplies the cooling means as a function of an estimate of the temperature of the air supplied by an internal sensor. The invention also proposes a vehicle, possibly of automobile type, and comprising a gearbox, a heat engine, and a clutch of the type presented above and coupled to the gearbox and to the heat engine. Other features and advantages of the invention will appear on examining the detailed description below, and the accompanying drawings (obtained for two of them in CAD / DAO, hence the apparently discontinuous nature of certain lines and gray levels), in which: FIG. 1 illustrates schematically and functionally an example of a motor vehicle comprising a first embodiment of a clutch according to the invention coupled to a cooling circuit of the heat engine, FIG. 2 schematically illustrates, in a longitudinal sectional view, a second embodiment of a clutch according to the invention, and FIG. 3 schematically illustrates, in a perspective view, a part of the clutch of FIG. 2. The object of the invention is notably to propose an EM clutch intended to ensure a coupling between a thermal engine MT and a gearbox BV and having MR cooling means internal. In what follows, by way of nonlimiting example, the clutch EM, the heat engine MT and the gearbox BV are intended to equip a vehicle V of automobile type, such as a car. But the invention is not limited to this application. It concerns in fact any system comprising at least one gearbox to be coupled to a heat engine via a clutch. Therefore, the invention particularly relates to land vehicles (cars, motorcycles, commercial vehicles, coaches (or buses), trucks, road vehicles, construction machinery, handling equipment, trains), river or maritime vehicles, 15 aircraft, certain buildings (public or private), and certain industrial installations (public or private). In addition, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a powertrain (or GMP) of conventional type, that is to say comprising only a thermal engine MT. But the vehicle V could be of the hybrid type (in this case it comprises at least one heat engine MT and at least one auxiliary machine for generating torque (possibly of the electric type)). FIG. 1 schematically illustrates a non-limiting example of a conventional powertrain vehicle V, and here of automobile type. As illustrated, this vehicle V comprises at least one heat engine MT, an engine shaft AM, a gearbox BV, and a clutch EM according to the invention. The thermal engine MT comprises a shaft (motor) AM which can be rotated to provide torque to the clutch EM. For example, this AM shaft is a crankshaft. The transmission BV conventionally comprises a primary shaft (or input) AP and a secondary shaft (or output) AS intended to be coupled to each other in order to transmit the torque (motor) provided by the 3025270 6 MT heat engine, via EM clutch. The primary shaft AP is designed to receive the motor torque via the EM clutch. The secondary shaft AS is intended to receive the motor torque via the primary shaft AP in order to communicate it to a train (here the front train TV, by way of non-limiting example), via a differential DV and possibly via a drive shaft. As illustrated in FIG. 2, the clutch EM, according to the invention, comprises a housing CE defining at least partially an internal cavity C1 housing a flywheel VM, at least one friction disk DF, a pressure mechanism MP (comprising at least one pressure plate PP and a cover CV, and a possible diaphragm DE), and cooling means MR. The VM flywheel can be single or dual (primary and secondary). It is intended to be firmly fixed to the shaft AM of the heat engine MT.

The friction disk DF is intended to be secured, in rotation but free in translation, to the primary shaft AP of the gearbox BV. The pressure plate PP is arranged to press the friction disk DF against the flywheel VM when it is pushed by a member DE, such as a diaphragm, in a clutch phase. This diaphragm DE 20 is in contact with a stop BE which is responsible for compressing it when it is actuated by a clutch control CE (which here comprises a clutch pedal). The cover CV is fixedly fixed to the VM flywheel and houses the pressure plate PP.

Furthermore, the pressure mechanism MP is provided with first openings 01, intended to allow a clean air inlet to cool the parts involved in the friction (VM, DF, PP), and peripheral (or radial) openings. OP, intended to allow the output of this cooling air in the vicinity of the flywheel VM / CV cover junction.

The first openings 01 are defined in the cover CV and / or in the possible diaphragm DE. Note that in the non-limiting example illustrated in Figure 2, the first openings 01 are defined in the lid CV and in the diaphragm DE. It will also be noted that the air 3025270 7 penetrates substantially axially through the first openings 01 defined in the diaphragm DE. The peripheral openings OP are defined in the cover CV facing a peripheral portion PE of the internal face FI of the housing CE.

The cooling air thus enters the space defined by the cover CV and the flywheel VM via the first openings 01, and is then accelerated by its friction between the tangential surfaces of the clutch EM (by a turbine effect). , then is radially evacuated through the peripheral openings OP of the cover CV, and finally is sucked to the abutment BE 10 before crossing again the first openings 01 and then being accelerated again by its friction between the tangential surfaces of the clutch EM, and so on. The cooling means MR are housed on the internal face FI of the casing CE in at least one location located on the path of the cooling air downstream of the peripheral openings OP. In addition, these MR cooling means contain a heat transfer fluid which is adapted to capture calories contained in the cooling air to cool the latter. The coolant can be either circulating inside the cooling means MR, or permanently contained (or prisoner) inside the latter (MR). It may for example be a coolant such as water, possibly supplemented with at least one additive. In the exemplary embodiments illustrated in non-limiting manner in FIGS. 1 and 3, the cooling means MR are arranged to be supplied with heat transfer fluid flowing through an external cooling circuit CR. It will be noted that in these examples the cooling circuit CR is the one that is responsible for cooling the heat engine MT. This cooling circuit CR thus ensures, here, the fluidic coupling between the thermal motor MT (and more specifically an internal cooling circuit that it comprises) and a cooling radiator RR. The coupling between the cooling circuit CR and the cooling means MR is effected via a distribution module MD, such as, for example, what a person skilled in the art 3025270 8 calls a "modulo". The latter (MD) comprises a main inlet coupled to an upstream portion of an outlet pipe of the cooling radiator RR, an auxiliary outlet coupled to a feed pipe of the cooling means MR (responsible for feeding the latter (MR ) in heat transfer fluid), an auxiliary input coupled to an exhaust duct MR cooling means (responsible for evacuating from them (MR) heat transfer fluid heated by the calories captured in the cooling indoor air flowing in the clutch housing CE), and a main output coupled to a downstream portion of this output hose. Preferably, the auxiliary input of the modulo MD is arranged to take only a small part of the coolant flowing in the upstream portion of the outlet hose, so that the remaining portion (majority) of the coolant feeds the MT heat engine. It should be noted that the cooling circuit CR could be part of another cooling system than that which is responsible for cooling the heat engine MT. Thus, it could be part of the air conditioning system (here of the vehicle V), or the cooling system of the gearbox BV, or a cooling system dedicated to the EM clutch. When the heat transfer fluid is flowing in the cooling means MR, the latter (MR) can, for example and as illustrated without limitation in FIGS. 1 to 3, comprise at least one heat exchanger Ei of the air / heat transfer fluid type. In the two examples illustrated nonlimitingly in FIGS. 1 to 3, the cooling means MR comprise a first heat exchanger El (i = 1) of the air / heat transfer fluid type which is installed on the peripheral portion PE of the internal face. FI of the housing CE (which is located opposite peripheral openings OP), and which is powered by the cooling circuit CR. The shape of this first heat exchanger El preferably embraces all or part of the shape (here substantially circular) of the peripheral portion PE of the inner face FI. In this case, the first heat exchanger El has a shape at least partly annular. It will be understood that the cooling air, which flows radially through the peripheral openings OP of the cover CV, comes into contact with the first heat exchanger E1, which enables it to transfer part of its heat to the cold heat transfer fluid which circulates. in this heat exchanger El and which comes here from the cooling radiator RR via modulo MD. The heat transfer fluid, which has captured the calories from the cooling air, 5 then becomes warmer than initially (it has actually gone from cold to warm), and returns to the cooling circuit CR via the modulo MD where it is mixed with the rest of the heat transfer fluid that has not been reheated. It will be noted that in the example illustrated nonlimitingly in FIGS. 2 and 3, the cooling means MR also comprise a second heat exchanger E2 (i = 2) of the air / heat transfer fluid type and a third heat exchanger E3 (FIG. i = 3) of air / heat transfer fluid type which are installed on a downstream portion PV of the inner face FI of the casing CE, which is intended to be located in the vicinity of the gearbox BV. These heat exchangers E2 and E3 may, for example, have rectangular general shapes adapted to the environment in which they are implanted. It will be understood that the cooling air, which flows radially through the peripheral openings OP of the cover CV, comes into contact with the three heat exchangers E1 to E3, which enables it to transfer a large part of its heat to the cold heat transfer fluid which circulates in these 20 heat exchangers E1 to E3 and which originates here from the cooling radiator RR via modulo MD. In other examples of circulating coolant embodiments, not shown, the cooling means MR could comprise only one heat exchanger E2 or E3 of the air / heat transfer fluid type, installed on the downstream portion PV of the face. internal FI of the casing CE, or at least two heat exchangers Ei type air / heat transfer fluid, installed on the downstream portion PV of the inner face FI of the casing CE, or include an heat exchanger El of air / heat transfer fluid type installed on the peripheral portion PE of the inner face FI of the casing CE, and more than two heat exchangers Ei type air / heat transfer fluid, installed on the downstream portion PV of the internal face FI of the casing CE. It will be noted that when the cooling means MR comprise several heat exchangers Ei of air / heat transfer fluid type, the latter (Ei) are preferably supplied in parallel by at least one distribution module MD, such as for example a modulo. In this case, the auxiliary output of the modulo MD can feed the different heat exchangers Ei, and the auxiliary input of the modulo MD can collect the coolant having circulated in the different heat exchangers Ei. In still other embodiments, not illustrated, the cooling means MR may comprise at least one channel defined in the peripheral portion PE of the inner face FI of the casing CE and containing at least the coolant. It will be understood that the cooling means MR can not comprise both such a channel and a first heat exchanger E1 because there is not enough space on the peripheral portion PE of the internal face FI of the casing CE. On the other hand, the cooling means MR may comprise both a channel defined in the peripheral portion PE of the internal face FI of the casing CE and at least one heat exchanger E2, E3 installed on the downstream portion PV of the internal face. FI of the CE casing. Moreover, the channel may be either non-opening and in this case it contains permanently the same coolant (it can then be defined for example by a so-called "lost wax" technique during the molding step of the casing CE , for example), either opening and in this case it allows a circulation of a heat transfer fluid from the cooling circuit CR (it can then be defined for example by machining after the molding step of the housing CE, for example). It should be noted that a non-through channel may also be an open channel whose open ends have been obstructed (for example by a friction welding technique). When the channel is open, it comprises an input and an output which are intended to be coupled respectively to auxiliary and auxiliary input of the cooling circuit CR (for example those of the modulo MD) via ducts (or pipes or hoses). ).

When the channel is non-opening, it may optionally comprise a coolant intended to liquefy beyond a certain temperature threshold from which it has very good heat conduction characteristics. Such heat transfer fluid may, for example, be sodium, or lithium (for example in the form of salts), or potassium (for example in the form of salts). For example, sodium has a liquefaction point at about 97.5 ° C. Note that when the channel is non-opening, it may be advantageous that it comprises a sealed sub-part, containing a coolant, and adapted to be surrounded by the heat transfer fluid trapped so that a portion of the calories transferred into the fluid coolant can be captured by the coolant to cool it. This option can significantly improve cooling efficiency of the cooling air. This heat transfer product may be intended to liquefy beyond a certain temperature threshold from which it has very good heat conduction characteristics. For example, it may be sodium, or lithium (for example in the form of salts), or potassium (for example in the form of salts).

It should be noted that the channel could be defined in the downstream portion PV of the inner face FI of the casing CE, but this induces a less efficient cooling of the cooling air. It will also be noted that when the cooling means MR allow the circulation of the coolant, it is possible, optionally, to manage the temperature of the cooling air flowing in the casing CE. To do this, it is possible to use control means arranged to control the quantity of heat transfer fluid which supplies the cooling means MR as a function of an estimate of the temperature of the cooling air supplied by an internal sensor to the clutch. EM (for example located in the MR cooling means). For example, these control means may comprise a thermostat comprising a heat-sensitive material that expands with temperature. This management can in particular make it possible, on the one hand, to rapidly increase the temperature of the cooling air in the case CE 30 during periods of extreme cold when the grease of the double damping flywheel can solidify and thus prevent the engine to start, and secondly, to regulate the temperature of the cooling air in the crankcase CE to an optimum operating point to avoid overheating and / or at least partial destruction of the clutch EM. The invention offers several advantages, among which: a reduction in the production of CO2 due to the reduction of the energy injected to achieve the friction during the clutch / clutch phases, which is induced by the significant reduction in the temperature inside the clutch, - an increase in the life of the clutch.

Claims (10)

REVENDICATIONS1. Clutch (EM) comprising a housing (CE) housing i) a flywheel (VM) adapted to be secured to a shaft (AM) of a heat engine (MT), ii) at least one friction disk (DF) clean to be secured to a primary shaft (AP) of a gearbox (BV), and iii) a pressure mechanism (MP) comprising at least one pressure plate (PP), suitable for pressing said friction disk (DF) ) against said flywheel (VM), a cover (CV), fixedly secured to said flywheel (VM) and housing said pressure plate (PP), first openings (01) for the air inlet, and peripheral openings (OP) for the output of said air, characterized in that said housing (CE) furthermore accommodates, on an inner face (FI) and in the path of said air downstream of said peripheral openings (OP), means 15 coolant (MR) containing a heat transfer fluid capable of capturing calories contained in this air in order to cool the air. 2. Clutch according to claim 1, characterized in that said cooling means (MR) are arranged to be supplied with circulating heat transfer fluid, by an external cooling circuit (CR). 20 3. Clutch according to claim 2, characterized in that said cooling means (MR) comprise at least one heat exchanger (Ei) of the air / heat transfer fluid type. 4. Clutch according to claim 3, characterized in that at least one heat exchanger (E2, E3) of air / heat transfer fluid type is installed on a downstream part (PV) of said inner face (FI) of the housing ( CE) intended to be situated in the vicinity of said gearbox (BV). 5. Clutch according to one of claims 3 and 4, characterized in that a heat exchanger (El) air / heat transfer fluid type is installed on a peripheral portion (PE) of said inner face (FI) of the housing ( CE) which is located opposite said peripheral openings (OP). 6. Clutch according to claim 1, characterized in that said cooling means (MR) comprise at least one channel defined in a peripheral portion (PE) of said inner face (FI) of the housing (CE) which is 3025270 14 located in view of said peripheral openings (OP) and containing at least said heat transfer fluid. Clutch according to Claim 6 in combination with one of Claims 2 to 4, characterized in that said channel comprises an inlet and an outlet intended to be coupled respectively to auxiliary and auxiliary input of said cooling circuit (CR ) external. 8. Clutch according to claims 1 to 7, characterized in that it further comprises control means arranged to control the amount of heat transfer fluid supplying said cooling means (MR) according to an estimate of the temperature of the supplied by an internal sensor. 9. Clutch according to claim 6, characterized in that said channel is non-opening and comprises a sealed sub-part, containing a heat-transfer product, and adapted to be surrounded by said coolant so that a portion of the calories transferred into said coolant can be captured by said heat transfer product to cool it. 10. Vehicle (V) comprising a gearbox (BV) and a heat engine (MT), characterized in that it further comprises a clutch (EM) according to one of the preceding claims, coupled to said gearbox (BV) and said heat engine (MT) .20