Patent Description:
Dual clutch transmission (DCT) systems are known as such for providing a transmission of torque, in particular in a vehicle. In a known DCT system, two torque transmitting assemblies, e.g. clutches, are provided. Each clutch is typically operated hydraulically, for example automatically as part of an automated transmission system. In particular, a clutch can thus be engaged and subsequently disengaged by changing (e.g. increasing, respectively decreasing), a hydraulic clutch control pressure (e.g. for controlling a clutch operating piston or other hydraulic operating member of the clutch).

One particular application of dual clutch transmission systems is in hybrid vehicles which comprise both an internal combustion engine and an electromotor. In such a context, one clutch of the system can be associated with the electromotor, the other with the combustion engine.

Torque transmitting assemblies such as clutches tend to generate heat during operation, requiring active cooling to avoid overheating and associated problems. In this respect it is known as such to provide a flow of transmission cooling fluid through such a torque transmitting assembly, wherein generated heat can be transferred to the cooling fluid which is subsequently led away from the assembly. Heat generation may be different in different clutches in the same transmission system, and the difference may vary over time.

At the same time, it is also generally desired to limit supplies of cooling fluid to clutches in view of overall efficiency and since an excess supply of fluid may negatively affect a clutch's performance. Thus, a particular challenge in transmission systems with multiple clutches, such as dual clutch transmission systems, is to appropriately regulate respective supplies of cooling fluid to respective clutches during operation, in particular in response to variable heat generation at one or each clutch. In this respect, known systems comprise complex cooling supply regulating means, wherein such complexity is known to make systems less reliable and more expensive to manufacture and maintain.

For example, <CIT> discloses a change-speed transmission in the power train of a motor vehicle, the transmission having a direct clutch and a reverse clutch, wherein at least a clutch which is engaged is cooled by a lubricant for a planetary gearing, wherein the flow of coolant to the clutches is regulated by an axially movable pressure plate of one of the clutches.

Other clutches with cooling are known from <CIT> and <CIT>.

An object of the present invention is to provide an improved dual clutch transmission (DCT) system and an improved method of cooling at least part of such a system, wherein at least one of the above-mentioned problems is at least partly solved. An object is to provide a DCT system wherein cooling of respective clutches can be better regulated. An object is to provide a relatively simple design for a DCT system, in particular with a relatively small number of moving parts. An object is to provide a method of cooling clutches in a DCT system wherein a cooling of one clutch can be regulated in particular without significantly affecting a simultaneous cooling of another clutch. An object is to provide a vehicle, for example a hybrid vehicle, with an improved DCT system.

At least one or some of the above objects can be realized, at least partly, by one or more aspects of the present invention.

An aspect of the present invention provides a dual clutch transmission (DCT) system, including coaxial first and second engageable and disengageable torque transmitting assemblies, configured to be installed in a power train of a vehicle. The DCT system includes a main flow path for supply of cooling fluid. The main flow path branches into a first flow path for supply of cooling fluid to the first torque transmitting assembly, and a second flow path for supply of cooling fluid to the second torque transmitting assembly.

The DCT system further includes a third flow path for supplying cooling fluid, which is discharged from the second torque transmitting assembly, to the first torque transmitting assembly. Preferably, the third flow path is arranged within a space defined by a housing of the dual clutch transmission system (in particular such that all the cooling fluid that is discharged out of the second torque transmitting assembly can be led directly into the first torque transmitting assembly, to be discharged from the housing via that first assembly).

In such a system, the second torque transmitting assembly can be efficiently cooled by a supply of cooling fluid (the fluid in particularly being led through and/or along heat generating torque transmitting components thereof to receive heat therefrom), which cooling fluid emanates from a branched off part of a total amount of cooling fluid that enters the system (e.g. a respective housing) via said main flow path. At the same time, the first torque transmitting assembly can receive a remaining part of the total amount of supplied cooling fluid (which fluid is supplied via the first flow path through and/or along torque transmitting components of that first torque transmitting assembly, e.g. to receive heat therefrom), but still receives (preferably all) cooling fluid that is discharged from second torque transmitting assembly. Preferably, the amount of cooling fluid fed to the second torque transmitting assembly is adjustable of variable, for example between/from zero (no flow) and/to a predetermined or desired amount.

It follows that a supply of cooling fluid to the second torque transmitting assembly can be achieved (being e. g adjustable or variable) substantially without affecting a net supply of cooling fluid to the first torque transmitting assembly. Moreover, such a system can have a relatively simple design, in particular enabling appropriate cooling of two torque transmitting assemblies (e.g. at the same time) using for example a single source of cooling fluid.

It should be observed that in this application, fluid flow can be expressed in various ways, for example in a flow rate or flow amount, e.g. a fluid volume per minute (volume flow rate), fluid mass per minute (mass flow rate) or the-like, as will be appreciated by the skilled person.

According to a further embodiment, the DCT system may include a flow regulator configured to regulate the supply of cooling fluid to the second torque transmitting assembly through the second flow path, in particular relative to the supply of cooling fluid to the first torque transmitting assembly through the first flow path and/or relative to the supply of cooling fluid through the main flow path.

Such a flow regulator can provide improved, in particular variable, regulation of the supply of cooling fluid to the second torque transmitting assembly (e.g. for switching the respective fluid supply to the second torque transmitting assembly on and off).

A flow regulating state of the flow regulator may be dependent on a torque transmitting state of the second torque transmitting assembly.

In this way, for example, an increased supply of cooling fluid can be provided to the second torque transmitting assembly when the second torque transmitting assembly transmits (more) torque and thereby generates (more) heat.

In particular, during operation, the second torque transmitting assembly is either disengaged (during which supply of cooling fluid to that assembly is blocked) or the second torque transmitting assembly is transmitting torque i.e. engaged (during which the supply of cooling liquid to that assembly is not blocked).

Preferably, at least part of the flow regulator is integrated with or associated with a movable part of the second torque transmitting assembly.

Such an integration or associated can enable a relatively simple, durable, design, in particular with fewer moving parts.

Preferably, the flow regulator has a first state when the second torque transmitting assembly is in a torque transmitting engaged state, wherein the flow regulator has a second state when the second torque transmitting assembly is in a torque non-transmitting disengaged state.

In the first state, compared to the second state, the flow regulator may be configured to provide an increased supply of cooling fluid to the second torque transmitting assembly through the second flow path, at least increased with respect to the supply of cooling fluid through the first flow path and/or the main flow path.

In this way, an increased supply of cooling fluid can be provided to the second torque transmitting assembly when the second torque transmitting assembly transmits torque and thereby generates (more) heat.

In the first state, for example about <NUM>% of the supply of cooling fluid through the main flow path can thus be supplied to the second torque transmitting assembly and/or about <NUM>% of the supply of cooling fluid through the main flow path can thus be supplied into the first flow path. In has been found that such a configuration can provide appropriate cooling of the first and second torque transmitting assemblies. It should be noted that other ratios than the <NUM>%-<NUM>% example are also envisaged, as is explained below.

In the second state, the flow regulator is preferably configured to substantially or totally block the supply of cooling fluid (via the second fluid path) to the second torque transmitting assembly through the second flow path. In this way, i.e. by preventing/blocking cooling of a disengaged second torque transmitting assembly (an 'open clutch') efficient use of cooling fluid is achieved, and relatively low transmission losses.

Thus, (more) cooling fluid can be supplied (more) directly to the first torque transmitting assembly, in particular when the second torque transmitting assembly generates less or substantially no heat.

The second torque transmitting assembly may be provided with a respective operating member which is (axially) movable between a coupling position in which the second torque transmitting assembly is engaged and a decoupling position in which the second torque transmitting assembly is disengaged. The operating member can in particular be a clutch piston.

The operating member of the second torque transmitting assembly may be connected to the flow regulator or can form or provide part thereof, for setting a flow regulating state of the flow regulator.

Such an operating member, e.g. piston, can advantageously enable that a state of the flow regulator is coupled to an engagement state of the second torque transmitting assembly, in particular in a simple and robust way.

A switching of an engagement state of the first torque transmitting assembly is preferably substantially independent from the position or state of the operating member of the second torque transmitting assembly.

In this way, a versatile DCT system can be provided, wherein one or more torque transmitting assemblies can be engaged and/or disengaged substantially independently from the or each other.

The movable operating member of the second torque transmitting assembly may be arranged to act as a valve member of the flow regulator, in particular providing a flow regulating section thereof, wherein said flow regulating section is movable onto and away from a valve seat that defines part of the second flow path, for closing and opening that flow path, respectively.

Such a configuration can provide a simple and robust design for the operating member and/or the flow regulator.

The valve seat may be configured for inhibiting, in particular blocking, an axial movement of the operating member in a first axial direction, upon mutual mechanical contact.

Thus, an elegant design can be provided, wherein the valve seat serves an additional purpose for the operating member. In other words, the valve seat can thus be integrated in means for advantageously preventing an excess movement of the operating member (e.g. piston) beyond the disengagement position from the engagement position.

The DCT system preferably includes spring means for moving the operating member in said first axial direction using respective spring force.

Such spring means can enable that the operating member is brought to its disengagement position and/or that the valve member is positioned onto the valve seat, in particular in the absence of a, e.g. hydraulic, actuation of the operating member.

One of the first and second torque transmitting assemblies may comprise an inner clutch, wherein the other of the first and second torque transmitting assemblies comprises an outer clutch. Preferably the second torque transmitting assembly comprises the inner clutch.

It has been found that application of the invention can be particularly advantageous with such a configuration. Alternatively, the first torque transmitting assembly may comprise the inner clutch.

The DCT system may be configured to combine the respective supplies of cooling fluid through the first flow path and the third flow path at the first torque transmitting assembly, wherein the thus combined supply of cooling fluid at the first torque transmitting assembly substantially corresponds to the supply of cooling fluid through the main flow path.

In this way, the supply of cooling fluid to the first torque transmitting assembly can be substantially independent of a variable supply of cooling fluid to the second torque transmitting assembly.

The DCT system may further comprise a source of transmission cooling fluid from which source the main flow path extends. Said source is preferably configured to regulate the flow of cooling fluid through the main flow path.

Such a dedicated transmission fluid source can thus provide respective supplies of cooling fluid to both the first and second torque transmitting assemblies.

Also, in an embodiment, the fluid source can be configured for circulating the cooling fluid to and from the torque transmission assemblies (e.g. to a respect joint housing of those assemblies), and e.g. for removing heat from cooling fluid (to surroundings) to cool that fluid. The skilled person will appreciated that a respective transmission fluid pump means (pump) can be associated with or be part of the system to achieve flow or circulation of the fluid.

The second torque transmitting assembly may be configured for receiving torque from an electromotor of a hybrid vehicle. For example, the DCT system may be a DCT system for a hybrid vehicle with an internal combustion engine and an electromotor.

The invention can find particular advantage in such a DCT system, wherein for example the second torque transmitting assembly is only occasionally engaged and/or wherein for example supply of cooling fluid to the second torque transmitting assembly requires less precise regulation of its supply of cooling fluid compared to the first torque transmitting assembly.

In an aspect of the invention a vehicle, for example a hybrid vehicle with an internal combustion engine and an electromotor, comprises a dual clutch transmission system according to an aspect of the invention.

Such a vehicle can provide one or more above-mentioned advantages.

It will be appreciated that the invention is not limited to hybrid vehicles since the DCT system can also be installed in vehicles having one or more electromotor drives only, or in vehicles having a combustion engine only, or differently.

An aspect of the invention provides a method of cooling at least one of a plurality of torque transmitting assemblies of a dual clutch transmission (DCT) system, for example utilizing an above-mentioned DCT system according the invention. The method comprises: supplying cooling fluid into a second of the torque transmitting assemblies (in particular for receiving heat therefrom); discharging cooling fluid (e.g. heated by the second torqye transmitting assembly) from said second of the torque transmitting assemblies; and supplying cooling fluid which has been discharged from said second of the torque transmitting assemblies, preferably directly, to a first of the torque transmitting assemblies.

Such a method can provide one or more above-mentioned advantages.

The method may further comprise: regulating the supply of cooling fluid to the second of the torque transmitting assemblies relative to a simultaneous supply of cooling fluid to the first of the torque transmitting assemblies.

The regulating may comprise: engaging the second of the torque transmitting assemblies (in particular from a disengaged state), thereby substantially increasing a or the supply of cooling fluid to the second of the torque transmitting assemblies (for example from zero supply), in particular relative to the simultaneous supply of cooling fluid to the first of the torque transmitting assemblies, in particular such that a ratio P of the (increased) supply (P2) of cooling fluid to the second of the torque transmitting assemblies as a fraction of the simultaneous supply (P1) of cooling fluid to the first of the torque transmitting assemblies (P1), (P=P2:P1), is between <NUM>:<NUM> and <NUM>: <NUM>, preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, for example about <NUM>:<NUM> or about <NUM>:<NUM>.

The regulating may comprise: disengaging the second of the torque transmitting assemblies, thereby substantially reducing, preferably substantially or totally blocking, the supply of cooling fluid to the second of the torque transmitting assemblies, in particular relative to the simultaneous supply of cooling fluid to the first of the torque transmitting assemblies (and in particular such that substantially none of the cooling fluid flows through the second torque transmitting assembly).

It will be appreciated that such engaging and disengaging of the torque transmitting assembly occur in particular at mutually different times. Thus, the disengaging may be a subsequent disengaging, in particular subsequent after the engaging, and vice versa.

The invention will be elucidated further using exemplary embodiments and drawings. The drawings are schematic. In the drawings, the same or similar elements have been provided with the same or similar reference signs. In the drawings:.

<FIG>, <FIG>, and <FIG> show examples of a dual clutch transmission system <NUM>, wherein <FIG> each show a cooling fluid flow chart of such a system.

The system <NUM> includes coaxial first <NUM> and second <NUM> engageable and disengageable torque transmitting assemblies, configured to be installed in a power train of a vehicle <NUM>. Diagrams of a respective vehicle <NUM> are shown in <FIG>.

A main axis A of the system <NUM> is shown in <FIG> and <FIG>. It will be appreciated that in those figures, the main axis A corresponds to a line of at least substantial symmetry, wherein corresponding mirrored structures of those shown on one side of the axis A are substantially (e.g. partly) mirrored on the other side of the axis A. As such, such a cross sectional view will be familiar to and readily understood by those skilled in the art of transmission systems (see also e.g. the drawings of aforementioned <CIT>).

The system <NUM> includes a main flow path <NUM> for supply of cooling fluid, wherein the main flow path <NUM> branches into a first flow path <NUM> for supply of cooling fluid to the first torque transmitting assembly <NUM>, and a second flow path <NUM> for supply of cooling fluid to the second torque transmitting assembly <NUM>. The system <NUM> includes a third flow path <NUM> for supplying cooling fluid, which is discharged from the second torque transmitting assembly <NUM>, to the first torque transmitting assembly <NUM>.

During operation, as cooling fluid is in contact with, e.g. flows through, a torque transmitting assembly <NUM> and/or <NUM> of the system <NUM>, the cooling fluid can receive heat from the respective torque transmitting assembly <NUM> and/or <NUM>. It will be appreciated that a cooling fluid can be supplied in the form of a transmission fluid, for example, wherein such a supply of transmission fluid can serve a dual purpose of both cooling and lubricating the system <NUM> or at least a part thereof, for example the torque transmitting assemblies <NUM> and <NUM>.

The third flow path <NUM> is preferably arranged within a space defined by a housing <NUM> of the dual clutch transmission system <NUM>. <FIG> show such a housing <NUM> as a structure or combination of structures which substantially surrounds and/or encloses both the first <NUM> and second <NUM> torque transmitting assemblies. Preferably, such a housing <NUM>, which is known as such in the context of transmission systems, at least partly retains (directly or indirectly) said torque transmitting assemblies <NUM>, <NUM> in their respective locations.

As shown in <FIG>, the housing <NUM>, in particular a part, e.g. including one or more walls and/or shells, which adjoin and/or surround the second torque transmitting assembly <NUM>, <NUM>, can comprise or provide the third flow path <NUM>, <NUM> in the form of one or more openings <NUM>, <NUM> therein, wherein said openings <NUM>, <NUM> provide (part of) a fluid connection from the second torque transmitting assembly <NUM>, <NUM> towards the first torque transmitting assembly <NUM>.

In <FIG>, the housing <NUM> can be seen as substantially surrounding the first <NUM> and second <NUM> torque transmitting assemblies.

The first torque transmitting assembly <NUM> is preferably provided with an outlet means <NUM> for discharge of cooling fluid from the first torque transmitting assembly <NUM>. In <FIG>, the outlet means <NUM> is denoted by arrow <NUM>. It will be appreciated that such outlet means <NUM> may be realized in various ways, at least some of which being known as such in the field of transmission systems.

In embodiments, the system <NUM> includes a flow regulator <NUM> configured to regulate the supply of cooling fluid to the second torque transmitting assembly <NUM> through the second flow path <NUM>, in particular relative to the supply of cooling fluid to the first torque transmitting assembly <NUM> through the first flow path <NUM> and/or relative to the supply of cooling fluid through the main flow path <NUM>.

<FIG> shows an exemplary flow regulator <NUM> in the form of a valve in the second flow path <NUM>. It will be appreciated that such a flow regulator <NUM>, while advantageous, is not strictly necessary to carry out the invention. For example, <FIG> shows a DCT system <NUM> without such a flow regulator.

In embodiments, a flow regulating state of the flow regulator <NUM> is dependent on a torque transmitting state of the second torque transmitting assembly <NUM>, wherein preferably at least part of the flow regulator <NUM> is integrated with or associated with a movable part <NUM> of the second torque transmitting assembly, wherein preferably the flow regulator <NUM> has a first state when the second torque transmitting assembly <NUM> is in a torque transmitting engaged state, wherein the flow regulator <NUM> has a second state when the second torque transmitting assembly <NUM> is in a torque non-transmitting disengaged state.

<FIG> and <FIG> show a DCT system <NUM>, <NUM> in such a second state, while <FIG> and <FIG> show the respective DCT system <NUM>, <NUM> in such a first state (and <FIG> shows detail C of <FIG>). It can be seen in those figures that a position of movable part <NUM>, <NUM> of the flow regulator <NUM>, <NUM> is different in the second state compared to the first state. In particular <FIG> show that in the first state (see <FIG>), compared to the second state (see <FIG>), the second torque transmitting assembly <NUM> is axially (more) compressed by the movable part <NUM>.

The movable part <NUM> may be movable, at least from one to another of the first and second states, in particular from the second state to the first state, by an increased pressure in a respective pressure chamber <NUM>, e.g. hydraulic pressure chamber <NUM>, associated with the second torque transmitting assembly <NUM>. Such a pressure chamber <NUM>, <NUM> is shown in <FIG> and <FIG> as a linearly hatched area, denoting a (more) pressurized state compared to <FIG> and <FIG>, respectively. Thus, a position of the movable part <NUM>, <NUM> may be substantially dependent on a pressurization state of the pressure chamber <NUM>, <NUM>.

It is further noted that the first torque transmitting assembly <NUM> may be provided with its own respective (independent) pressure chamber for (independently) operating a respective operating member <NUM> of the first torque transmitting assembly <NUM>.

Preferably, in the first state, compared to the second state, the flow regulator <NUM> is configured to provide an increased supply of cooling fluid to the second torque transmitting assembly <NUM> through the second flow path <NUM>, at least increased with respect to the supply of cooling fluid through the first flow path <NUM> and/or the main flow path <NUM>, for example such that about <NUM>% of the supply of cooling fluid through the main flow path <NUM> is thereby supplied to the second torque transmitting assembly <NUM> and/or such that about <NUM>% of the supply of cooling fluid through the main flow path <NUM> is thereby supplied into the first flow path <NUM>.

Preferably, in the second state (see <FIG> and <FIG>), the flow regulator <NUM>, <NUM> is configured to substantially block the supply of cooling fluid to the second torque transmitting assembly <NUM>, <NUM> through the second flow path <NUM>, <NUM>.

In embodiments, the second torque transmitting assembly <NUM> is provided with a respective operating member <NUM>, for example the movable part <NUM>, which is (axially) movable between a coupling position in which the second torque transmitting assembly <NUM> is engaged and a decoupling position in which the second torque transmitting assembly <NUM> is disengaged, the operating member <NUM> in particular being a clutch piston <NUM>.

Such an operating member <NUM> may be thus movable as described above with respect to the movable part <NUM>, wherein the movable part <NUM> may be the operating member <NUM>.

In embodiments, the operating member <NUM> of the second torque transmitting assembly <NUM> is connected to the flow regulator <NUM> or forms or provides part thereof, for setting a flow regulating state of the flow regulator <NUM>.

Preferably a switching of an engagement state of the first torque transmitting assembly <NUM>, for example via a respective operating member <NUM>, is substantially independent from the position or state of the operating member <NUM> of the second torque transmitting assembly <NUM>.

In embodiments, the movable operating member <NUM> of the second torque transmitting assembly <NUM> is arranged to act as a valve member <NUM> of the flow regulator <NUM>, in particular providing a flow regulating section <NUM>, <NUM> thereof (see <FIG>, <FIG>), wherein said flow regulating section <NUM> is movable onto and away from a valve seat <NUM> (see <FIG>) that defines part of the second flow path <NUM>, for closing and opening that flow path <NUM>, respectively.

Thus, for example, the valve member <NUM> may be movable onto and away from the valve seat <NUM> by a respective depressurization and pressurization of the pressure chamber <NUM>.

With reference to <FIG>, the valve seat <NUM> may be arranged at a downstream end of one or more holes <NUM> which form part of the second flow path <NUM>. Such holes <NUM> can for example extend axially through a shaft, e.g. an input shaft, of the system <NUM>. The holes <NUM> are preferably substantially evenly distributed around the main axis A to promote a substantially even flow of cooling fluid. The number of holes <NUM> and their dimensions (in particular diameter) can be selected to affect a desired flow and/or ratio of flows of cooling fluid. In one embodiment, six such holes <NUM> are provided. In another embodiment, twelve such holes <NUM> are provided.

In embodiments, the valve seat <NUM> is configured for inhibiting, in particular blocking, an axial movement of the operating member <NUM> in a first axial direction A1, upon mutual mechanical contact, the system <NUM> preferably including spring means <NUM> for moving the operating member <NUM> in said first axial direction A1 using respective spring force.

<FIG> and <FIG> show the spring means <NUM>, <NUM> as being (more) compressed compared to <FIG> and <FIG>, respectively.

The spring means <NUM> may be arranged in the second flow path <NUM>, for example in a respective spring chamber which forms part of the second flow path <NUM>, such that cooling fluid can flow through the spring means <NUM>. <FIG> and <FIG> show how in the first state (i.e. the second torque transmitting assembly <NUM>, <NUM> being in an engaged torque-transmitting state), cooling fluid can thus flow through the spring means <NUM>, <NUM>.

A compact design can thus be realized, wherein space occupied by the spring means <NUM>, <NUM> serves an additional purpose of providing a path for cooling fluid.

In embodiments, as shown for example in <FIG>, one of the first <NUM> and second <NUM> torque transmitting assemblies comprises an inner clutch <NUM>, wherein the other of the first <NUM> and second <NUM> torque transmitting assemblies comprises an outer clutch <NUM>, wherein preferably the second torque transmitting assembly <NUM> comprises the inner clutch <NUM>.

In embodiments, the DCT system is configured to combine the respective supplies of cooling fluid through the first flow path <NUM> and the third flow path <NUM> at the first torque transmitting assembly <NUM>, wherein the thus combined supply of cooling fluid at the first torque transmitting assembly <NUM> substantially corresponds to the supply of cooling fluid through the main flow path <NUM>.

The respective supplies may be thus combined within and/or near the first torque transmitting assembly <NUM>. As an example, <FIG> and <FIG> show the respective supplies as being combined just upstream of the first torque transmitting assembly <NUM>, just downstream of the third flow path <NUM>.

In embodiments, the DCT system further comprises a source <NUM> of cooling fluid from which source <NUM> the main flow path <NUM> extends, wherein said source <NUM> is preferably configured to regulate the flow of cooling fluid through the main flow path <NUM>.

In <FIG> and <FIG>, the source <NUM>, <NUM> is denoted by arrow <NUM>, <NUM>. It will be appreciated that the source <NUM>, <NUM> may be arranged at a distance, e.g. a greater distance than shown, from the first <NUM>, <NUM> and/or second <NUM>, <NUM> torque transmitting assemblies.

In embodiments, the DCT system further comprises a planetary gear set <NUM>. <FIG>, <FIG> show such a planetary gear set <NUM> diagrammatically. Also, in embodiments, the DCT system can include a shifting/brake clutch <NUM>, for receiving torque from the torque transmitting assemblies <NUM>, <NUM>.

The DCT system <NUM> can for example configured for a hybrid vehicle <NUM> with an internal combustion engine <NUM> and an electromotor <NUM>. With further reference to <FIG>, <FIG> in embodiments, the second torque transmitting assembly <NUM> is configured for receiving torque from an internal combustion engine <NUM> of a e.g. a hybrid vehicle <NUM>. The second torque transmitting assembly <NUM> can be connected or connectable to an optional planetary gear set <NUM> via a shifting/brake clutch <NUM> (see <FIG>), and input shaft <NUM> (see <FIG>), as will be appreciated by the skilled person.

<FIG> shows a diagram of a vehicle <NUM>, for example a hybrid vehicle <NUM> with an internal combustion engine <NUM> and an electromotor <NUM>, comprising the dual clutch transmission system <NUM>. In <FIG>, the first torque transmitting assembly <NUM> is in a decoupled state.

<FIG> is similar to <FIG>, showing the vehicle when the first torque transmitting assembly <NUM> is in a coupled state. As a result, the electromotor <NUM> is coupled, via input shaft <NUM> (shown between the second torque transmitting assembly <NUM> and shifting clutch <NUM> in the diagram), for delivering power to the powertrain.

A method of cooling at least one of a plurality of torque transmitting assemblies <NUM>, <NUM> of a dual clutch transmission system <NUM>, for example utilizing a system <NUM> as described above, comprises: supplying cooling fluid into a second <NUM> of the torque transmitting assemblies; discharging cooling fluid from said second <NUM> of the torque transmitting assemblies; and supplying cooling fluid which has been discharged from said second <NUM> of the torque transmitting assemblies, preferably directly, to a first <NUM> of the torque transmitting assemblies.

In embodiments, the method further comprises: regulating the supply of cooling fluid to the second <NUM> of the torque transmitting assemblies relative to a simultaneous supply of cooling fluid to the first <NUM> of the torque transmitting assemblies.

In embodiments, the regulating comprises: engaging the second <NUM> of the torque transmitting assemblies, thereby substantially increasing the supply of cooling fluid to the second <NUM> of the torque transmitting assemblies, in particular relative to the simultaneous supply of cooling fluid to the first <NUM> of the torque transmitting assemblies.

Said substantially increasing is in particular such that the supply of cooling fluid to the second <NUM> of the torque transmitting assemblies as a fraction of the simultaneous supply of cooling fluid to the first <NUM> of the torque transmitting assemblies corresponds to a ratio P, wherein P is preferably between <NUM>:<NUM> and <NUM>: <NUM>, e.g. preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, more preferably between <NUM>:<NUM> and <NUM>:<NUM>, for example about <NUM>:<NUM> to about <NUM>:<NUM>.

To this end, with reference to <FIG> and <FIG>, the DCT system <NUM> may comprise a constriction member <NUM> which provides a constriction <NUM> in the first flow path <NUM>, for example at a border between the main flow path <NUM> and the first flow path <NUM>. Such a constriction member <NUM> can be dimensioned to effect the ratio P, thereby providing simple and effective means to select an appropriate ratio P in a DCT system. The constriction member <NUM> is preferably configured to provide a substantially static or constant constriction, e.g. being substantially stiff, yielding a substantially constant ratio P (at least in the state for which P is defined, i.e. wherein the second <NUM> of the torque transmitting assemblies is engaged). Such a configuration can be particularly simple and robust.

The constriction member <NUM> may have a substantially L-shaped cross section, comprising a substantially radially extending section 322r and a substantially axially extending section 322a extending from an inner radial side of the radially extending section 322r. The radially extending section 322r may be provided with a series of respective grooves <NUM> through which cooling fluid can flow in the first flow path <NUM>, wherein for example the number of grooves and/or their dimensions (in particular transverse to the first flow path <NUM>) can be selected to affect a desired constriction <NUM> in the first flow path <NUM>. Alternatively or additionally, the axially extending section 322a can be provided with a series of holes (not shown) extending radially therethrough, wherein larger and/or more holes can thus provide a reduced flow constriction.

It will be appreciated that various parts of the DCT system, in particular those parts that form the first and second flow paths <NUM> and <NUM>, can thus be designed to affect desired flow resistances which in turn can yield a desired ratio of cooling fluid supplies (e.g. expressed as the ratio P as explained above). As one example, the system <NUM>, in particular the constriction member <NUM>, may be designed to provide a clearance of <NUM> at the constriction <NUM> in the first flow path <NUM>.

In embodiments, the regulating comprises disengaging the second <NUM> of the torque transmitting assemblies (in particular before and/or after the engaging), thereby substantially reducing, preferably substantially blocking, the supply of cooling fluid to the second <NUM> of the torque transmitting assemblies, in particular relative to the simultaneous supply of cooling fluid to the first <NUM> of the torque transmitting assemblies.

Claim 1:
A dual clutch transmission system (<NUM>), including coaxial first (<NUM>) and second (<NUM>) engageable and disengageable torque transmitting assemblies, configured to be installed in a power train of a vehicle (<NUM>), the system (<NUM>) including a main flow path (<NUM>) for supply of cooling fluid, wherein the main flow path (<NUM>) branches into a first flow path (<NUM>) for supply of cooling fluid to the first torque transmitting assembly (<NUM>), and a second flow path (<NUM>) for supply of cooling fluid to the second torque transmitting assembly (<NUM>),
wherein the system (<NUM>) includes a third flow path (<NUM>) for supplying cooling fluid, which is discharged from the second torque transmitting assembly (<NUM>), to the first torque transmitting assembly (<NUM>), the third flow path (<NUM>) preferably being arranged within a space defined by a housing (<NUM>) of the dual clutch transmission system (<NUM>).