Drive module and vehicle

Abstract

A drive module (2) configured for propelling a vehicle is provided. The drive module (2) comprises a housing (3), an electrical machine (4), a transmission (5) and a heat exchanger (6). The heat exchanger (6) is configured to cool a fluid for cooling the electric machine (4) and / or the transmission (5). A first side (S1) of the heat exchanger (6) is mounted to a fluid interface (7) configured to guide a cooling fluid to and from the heat exchanger (6). Specifically, a second side (S2) of the heat exchanger (6) comprises a heat exchanger flange protrusion (12) mounted coaxially and with axial overlap relative a housing flange protrusion (13) arranged on the inside of the housing (3), such that the heat exchanger is supported at two sides (SI, S2). The present disclosure further relates to a vehicle (1) comprising a drive module (2).

Description

The present disclosure relates in general to a drive module configured for propelling a vehicle, and to a vehicle comprising said drive module.BACKGROUNDThe powertrain of a vehicle is exposed to vibrations when the vehicle is travelling over a road surface or a ground surface. Even if the vehicle has a suspension system to absorb vibrations or to some extent prevent such vibrations to propagate into the chassis and further to the powertrain of the vehicle, it is not always possible to reduce the vibrations enough and the vibrations may over time lead to damage of components.For a vehicle to be economically attractive it needs to be designed for a long service life. The powertrain often includes complex and expensive components such as combustion engines and / or electric motors, transmissions and coolant systems. These types of components need to be designed to withstand vibrations and fatigue of materials. In some vehicle types a compact drive module may be configured to comprise an electric motor, a transmission and a heat exchanger, sometimes referred to as an oil cooler.In some powertrains the drive module is mounted at least partly on a drive axle of the vehicle in order to transmit propulsive torque to the wheels of the drive axle. Since the drive axle is receiving vibrations from the wheels, such vibrations may propagate into the drive module and the heat exchanger and over time cause fatigue and breakage. This situation may require that the vehicle is taken out of service for expensive repair or replacement of the heat exchanger.It is in general desired to reduce the size and weight of components in a vehicle powertrain, to save space and fuel consumption and also enable compact installation of the components. A drive module arranged at the vehicle drive shafts preferably has small outer dimensions and the components inside the drive module are therefore tightly packed. Such tight packaging is a challenge when assembling the drive module. Complicated fitting and fastening of drive module components to their correct position may increase the assembly time and thereby increase the cost of the product.The document WO2014048219A1 discusses an electric vehicle with a heat exchanger integrated assembly and a related manufacturing method. The document mentions poor performance of antivibration components, and also mentions heavy weight of the entire assembly. The proposed solution involves an integrated assembly comprising a heat exchanger, a mounting bracket and a valve. The assembly also involves an integrated expansion device that can easily be replaced.The document EP2990749A1 discusses the use of heat exchangers in many industries including vehicles. The document discusses a heat exchanger with a damping structure provided in a first fluid passage, and at least a part of the first fluid passage is in communication with a first pipe or a second pipe via the damping structure.SUMMARYA drive module of an electric vehicle should withstand vibrations and also be easy to assemble. Preferably it should also be compact. It would be advantageous to achieve a drive module that better addresses the challenges related to vibrations, easy assembly and compact design. The object of the present invention is to provide a robust and compact drive module which is easy to assemble. The drive module is configured to propel a vehicle.The object is achieved by the subject-matter of the appended independent claim(s).In accordance with the present disclosure, a drive module configured for propelling a vehicle is provided. The drive module comprises a housing, an electrical machine, a transmission and a heat exchanger. The heat exchanger is configured to cool a fluid for cooling the electric machine and / or the transmission. A first side of the heat exchanger is mounted to a fluid interface configured to guide a cooling fluid to and from the heat exchanger. Specifically, a second side of the heat exchanger comprises a heat exchanger flange protrusion mounted coaxially and with axial overlap relative a housing flange protrusion arranged on the inside of the housing, such that the heat exchanger is supported at two sides.By mounting the heat exchanger from two sides, to a fluid interface respectively a housing flange protrusion, the heat exchanger is supported from two sides and thereby restricted from severe swinging when exposed to vibrations, as may be the case if the heat exchanger was mounted, or supported, from one side only. Moreover, the heat exchanger flange protrusion enables easy guiding and fitting of a coaxially mounted housing flange protrusion, when the housing of the drive module is assembled around the heat exchanger. Further, the coaxial mounting of flange protrusions eliminates the need for additional fastening elements such as screws or bolts. The drive module according to the present disclosure thereby has resilience to vibrations while at the same time being easy and cost efficient to assemble.The heat exchanger flange protrusion and the housing flange protrusion may further have a cylindrical shape, meaning that that the cross sections of both flange protrusions are circular with the same diameter over different axial positions, i.e. like a cylinder. A cylindrical shape is a common shape for pipes and flanges and therefore equipment and processes for manufacturing the flange protrusions are more easily available and potentially less costly. A cylindrical shape also contributes to less sensitive positioning at the coaxial assembly of the two flange protrusions since any slight rotation of one or the other of the flange protrusions, around a fictive axial rotation axis, will not result in geometrically non-matching end sections of the flange protrusions. Less sensitive positioning of the flange protrusions during manufacturing enables a less costly and more robust manufacturing process. This contributes to a cost efficient manufacturing of the drive module.The housing flange protrusion may be arranged coaxially outside the heat exchanger flange protrusion. Thereby a larger and stronger housing flange protrusion is obtained, which may be preferred in some situations, for example in case of a heavier heat exchanger. The larger dimensions of an outer flange protrusion may also contribute to easier guiding of the housing flange protrusion onto a smaller heat exchanger flange protrusion during assembly. A drive module that is robust and easy to assemble may thus be achieved.The housing flange protrusion may alternatively be arranged coaxially inside the heat exchanger flange protrusion. Thereby the housing flange protrusion may have reduced dimensions, which may be preferred in some situations where the shape of the housing is setting constraints for the size and / or positioning of the housing flange protrusion. A more flexible positioning of the housing flange protrusion may be achieved. As a result the drive module may be adapted for flexible and thereby cost efficient manufacturing.Furthermore, a vibration dampening element may be arranged coaxially and axially and at least partly circumferentially between the housing flange protrusion and the heat exchanger flange protrusion. The vibration dampening element enables less exposure of the heat exchanger to vibration loads during operation of the vehicle. The vibration dampening element may be a rubber oring or v-ring. Such elements are proven to work well as vibration dampeners and are also common and easily available of good quality. The vibration dampening element thus contributes to achieving a more robust drive module.Furthermore, the heat exchanger flange protrusion may comprise a rim portion configured to position the vibration dampening element axially inside the rim portion. The rim portion reduces the risk for the vibration dampening element to move axially, assisted by vibrations, to a position axially outside the flange protrusion. In such a position the dampening element would no longer adequately fulfil its function as vibration dampener. The rim portion thus reduces the risk for wrong position and malfunction of the vibration dampening element and thereby increases the robustness of the drive module.A spring element may be arranged at an axial end surface of the heat exchanger flange protrusion and coaxially inside or outside the housing flange protrusion. The spring element provides a force acting on an axial end of the heat exchanger flange protrusion and thereby acts as an axial vibration dampening element. A more robust drive module is achieved. Moreover, the spring element provides a pre-tensioning of the heat exchanger towards the fluid interface mounted at a first side of the heat exchanger, in case the first side is opposite to the second side. Thereby the heat exchanger is securely positioned by the spring element towards the fluid interface. Additional robustness is thus enabled. Moreover, the spring element eliminates the need for extra fastening elements to fixedly position the heat exchanger at the fluid interface. This contributes to less articles / components involved a more cost efficient assembly.The present disclosure further provides a vehicle comprising a drive axle and a set of wheels. The vehicle further comprises a drive module as described above, wherein the drive module is connected to the drive axle.The vehicle may be a heavy land-based vehicle, such as a truck or a bus, but is not limited thereto. Moreover, the vehicle may be a fully electric vehicle or a hybrid vehicle.BRIEF DESCRIPTION OF DRAWINGSFig. 1 schematically illustrates a top view of an example of a vehicle according to the present disclosure,Fig. 2a schematically illustrates a first exemplifying embodiment of the drive module according to the present disclosure,Fig. 2b schematically illustrates a second exemplifying embodiment of a part of the drive module according to the present disclosure,Fig. 3a schematically illustrates a more detailed example of the first exemplifying embodiment of the drive module according to the present disclosure,Fig. 3b schematically illustrates a more detailed example of the second exemplifying embodiment of the drive module according to the present disclosure,Fig. 4 schematically illustrates an exemplifying embodiment of the assembly of the drive module according to the present disclosure.DETAILED DESCRIPTIONThe invention will hereafter be described in more detail below with reference to exemplifying embodiments and the accompanying drawings. The invention is however not limited to the exemplifying embodiments discussed and / or shown in the drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate the invention or features thereof. Well known functions or constructions will not necessarily be described in detail for brevity and / or clarity.In the present disclosure, the term "flange protrusion" is intended to mean a surface protruding from an object in a similar manner as the annular protrusion in the center of a flange. The flange protrusion is here used primarily as a bracket to arrange the protrusion coaxially relative a similar flange protrusion on another object. Put differently, the flange protrusion is mainly used for mounting an object to a similar flange protrusion on another object. A secondary function of the flange protrusion may be to guide a fluid. The circumferential shape of the flange protrusion, i.e. the cross-sectional shape, may be circular like a cylinder, but other shapes are possible, such as oval, rectangular, triangular or irregular shape. The axial extension of the flange protrusion is intended to have a substantially constant diameter or width, to enable coaxial fitting of two congruent flange protrusions relative each other.The present disclosure relates in general to a drive module configured for propelling a vehicle and the drive module is therefore a part of the powertrain of the vehicle. The drive module may also be referred to as a drive unit or propulsion unit. In this disclosure the drive module comprises an electric machine, a transmission and a heat exchanger. The drive module is configured to be connected to a drive shaft, or wheel axle, comprising wheels.The details of the transmission inside the drive module will not be explained in in this disclosure. In the following it is just briefly explained how the drive module may be connected to the drive shaft. The drive shaft is typically be a split shaft such that two half shafts are connected to a differential. The differential may be comprised in the drive module and connected to the transmission inside the drive module. When connecting the drive module to the half shafts of the drive axle, the half shafts suitably comprise splined end portions configured to be inserted into splined collars of the differential. Thus, the drive module may be connected to the drive shaft and provide propulsive power to the wheels.The vehicle powertrain may comprise more than one drive module. For example, two drive modules may be connected to the same drive shaft. Alternatively, multiple drive shafts may be provided with at least one drive module per drive shaft if the vehicle is driven via two or more wheel axles.The vehicle powertrain may comprise other types of propulsion units than a drive module according to the present disclosure, if desired. For example, the vehicle powertrain may comprise a combustion engine and a drive module and in that case it can be referred to as a hybrid vehicle. The present disclosure is not limited to any specific configuration of the vehicle powertrain.As mentioned earlier, the drive module comprises a heat exchanger configured to cool a fluid for cooling the electric machine and / or the transmission. The heat exchanger typically guides two separate coolant flows such that heat transfer from one flow to the other flow occurs. A first side of the heat exchanger is mounted to a first fluid interface, or media interface, configured to guide a cooling fluid to and from the heat exchanger. This first fluid interface may for example be in the form of an inlet pipe and an outlet pipe, or hose, or any kind of conduit suitable for guiding or circulation the coolant fluid to a radiator comprised in the vehicle coolant system. The vehicle coolant system will not be described in detail in this disclosure but may typically comprise a radiator, a pump, a filter and the like. The heat exchanger further comprises a second fluid interface configured to circulate a lubrication fluid, contained in the drive module, through the heat exchanger. The lubrication fluid may thus be cooled inside the heat exchanger by transferring heat to the cooling fluid.Instead of connecting the first fluid interface of the first side of the heat exchanger to an inlet pipe and outlet pipe, other possible connections are fully possible. For example, the first fluid interface may be directly connected to a housing interface arranged on the inside of the drive module housing. The housing interface may comprise an inlet and an outlet for guiding fluid to and from the heat exchanger, whereby the housing walls may have integrated fluid channels in the housing material for guiding the coolant to other positions in the drive module housing, where pipes or hoses or conduits may be connected for further guidance of the coolant fluid to the other parts of the vehicle coolant system. The coolant fluid may for example comprise water with additives for antifreeze, corrosion protection etc.Since the first side of the heat exchanger is connected to a first fluid interface such as pipes or a housing interface, this connection may be designed to be strong enough to at least partly support the weight of the heat exchanger. The mounting to a fluid interface thus has two functions; to enable a fluid connection with other parts of the vehicle cooling system and also to mechanically support the heat exchanger at the first side such that the first side is restricted from swinging when the heat exchanger is exposed to vibrations. This mounting principle with two-in-one functions thus eliminates the need for supporting the first side of the heat exchanger with extra brackets, which facilitates the assembly, reduces the number of components and thus saves space and weight.The heat exchanger further comprises a second side which comprises a heat exchanger flange protrusion mounted coaxially and with axial overlap relative a housing flange protrusion arranged on the inside of the housing, such that the heat exchanger is supported at two sides. By mounting the heat exchanger from two sides, to a fluid interface respectively a housing flange protrusion, the heat exchanger is supported from two sides and thereby restricted from severe swinging when exposed to vibrations, as may be the case if the heat exchanger was mounted, or supported, from one side only.Moreover, the second side of the heat exchanger comprising a flange protrusion can be easily located to a housing flange protrusion, when the housing is assembled around the heat exchanger. Put differently, when the heat exchanger has been mounted at a first side to a first fluid interface in the drive module, the housing with the housing flange protrusion can then be assembled onto the heat exchanger flange protrusion at the second side, whereby the mating flange protrusions are easy to locate and guide to a correct mounting position relative each other. Also, the mounting via two coaxial flange protrusions eliminates the need for screws or other fastening elements, which contributes to reduced number of parts, less weight, saved space, compactness and easy assembly of the drive module.Figure 1 schematically illustrates a top view of an example of a vehicle 1. The vehicle 1 comprises a powertrain having an electric drive axle configuration. The powertrain comprises a drive module 2 with a housing 3. The drive module 2 is connected to a drive shaft comprising wheels.The vehicle 1 may be a fully electric vehicle or a hybrid vehicle. The vehicle 1 is suitably a land-based heavy vehicle, but is not limited thereto. Furthermore, the vehicle 1 may be a vehicle configured to be operated by a driver, either present onboard the vehicle or being remote from the vehicle, or be a fully autonomous vehicle.Figure 2a schematically illustrates a first exemplifying embodiment of the drive module 2. The drive module 2 comprises an electrical machine 4 connected to a transmission 5. The drive module 2 further comprises a heat exchanger 6 having a first side SI and an opposite second side S2. The first side SI is mounted to a fluid interface 7, which may also be referred to as a first fluid interface 7, configured to guide a cooling fluid to and from the heat exchanger 6. The fluid interface 7 is connected to other typical parts of the vehicle coolant system such as a radiator, a pump, a filter etc. (not shown).The fluid interface 7 has two functions; it connects the heat exchanger 6 fluidly to the vehicle coolant system and it also supports a least partly the weight of the heat exchanger 6. The fluid interface 7 may comprise pipes or hoses of such dimension that that a suitable coolant flow can be transported, while the dimension and material of the pipes or hoses is selected such that they can support at least partly the weight of the heat exchanger 6. Thereby it is not necessary to support or fixate the first side SI of the heat exchanger 6 with separate brackets or fastening elements, which saves weight and assembly time.The mounting of the first side SI of the heat exchanger 6 onto the fluid interface 7 can thus be performed by sliding inlet and outlet openings, comprised in the first side SI of the heat exchanger 6, onto the pipes or hoses of the fluid interface 7. This enables a simple and quick procedure for mounting the heat exchanger 6 onto the fluid interface 7. The fluid interface 7 may comprise resilient members (not shown) such as o-rings, for sealing the fluid interface 7 from any leakage of coolant fluid while at the same time the resilient members provides a vibration dampening effect.As an alternative to mounting the first side SI of the heat exchanger 6 to a fluid interface 7 comprising pipes or hoses, the first side SI may be mounted to a fluid interface 7 which is integrated in an inside surface of the heat exchanger housing 3. The housing 3 may in that case comprise integrated coolant channels which are routed in the wall material of the housing 3, to a suitable position of the housing 3 where the coolant channels exits into pipes or hoses arranged outside the drive module 2, for further circulation of the coolant fluid in the vehicle coolant system (not shown).The heat exchanger 6 is configured to cool a lubrication fluid by circulating a flow of coolant such as water close to a separated flow of lubricant to be cooled. Heat can thereby be transferred from the lubrication fluid to the cooling fluid. In the present disclosure the lubrication fluid is contained inside the housing 3 of the drive module 2. The lubrication fluid lubricates and cools the electric machine 4 and / or the transmission 5. This function of cooling and lubricating the electric machine 4 and / or transmission 5 is not of particular interest for the present disclosure and will not be described in detail. In general, the lubrication fluid is typically guided to and distributed from the heat exchanger 6 via a fluid interface 8, which may also be referred to as a second fluid interface 8, indicated by dotted lines in figure 2a. The fluid interface 8 may for example comprise hoses or ducts connected to the heat exchanger 6. A pump may assist the flow of lubricant in the hoses or ducts (not shown).Figure 2a further illustrates a heat exchanger flange protrusion 12 arranged on a second side S2 of the heat exchanger 6. The heat exchanger flange protrusion 12 is mounted coaxially and with axial overlap relative a housing flange protrusion 13 arranged on the inside of the housing 3 . Thereby the housing flange protrusion 13 acts as a bracket for supporting heat exchanger flange protrusion 12. As a result the second side S2 of the heat exchanger 6 may be mounted to the inside of the housing 3 in a simple manner.Figure 2a schematically illustrates a housing flange protrusion 13 arranged coaxially outside the heat exchanger flange protrusion 12 and with axial overlap.Figure 2b schematically illustrates an exemplifying embodiment where the housing flange protrusion 13 is arranged coaxially inside the heat exchanger flange protrusion 12 and with axial overlap.Figure 2b further schematically illustrates an exemplifying embodiment where the first side SI of the heat exchanger 6 is not arranged opposite the second side S2, but on an adjacent side. This still enables the heat exchanger to be supported from two sides SI, S2 which restricts the heat exchanger 6 from swinging when exposed to vibrations.Figures 3a, 3b schematically illustrates an exemplifying embodiment where a vibration dampening element 10 is arranged coaxially and axially and at least partially circumferentially between the housing flange protrusion 13 and the heat exchanger flange protrusion 12.Figures 3a, 3b further schematically illustrates a heat exchanger flange protrusion 12 provided with a rim portion 9. The rim portion 9 is configured to position the vibration dampening element 10 axially inside the rim portion 9 and prevent it from sliding axially outside the flange protrusion 12.Figure 3a further schematically illustrates a spring element 11 arranged at an axial end surface of the heat exchanger flange protrusion 12 and coaxially inside the housing flange protrusion 13.Alternatively, as shown in figure 3b, the spring element may be arranged at an axial end surface of the heat exchanger flange protrusion 12 but coaxially outside the housing flange protrusion 13. The spring element may be in the form of a spiral spring of metal or plastic, or in the form of a an annular rubber tube. Other types of resilient members that may function as a spring element are possible.Figure 4 schematically illustrates a drive module 2 comprising a first housing section 3' and a second housing second 3" attachable to the first housing section 3' along an interface section S. When any of the first and / or second housing sections 3', 3" is / are moved in a direction D towards each other for closing the housing 3 of the drive module 2, the housing flange protrusion 13 is configured to be positioned coaxially and with axial overlap relative the heat exchanger flange protrusion 12.An axial overlap means that the end sections of the flange protrusions 12, 13 are overlapping each other axially. The overlap is required to achieve a support function, or bracket function, whereby the housing flange protrusion 13 supports at least partly the weight of the heat exchanger 6. The axial length of the overlap may be in the range of 2-50 mm, but is not limited thereto. The axial length of any of the flange protrusions 12, 13 may be in the range of 3-100 mm, but other lengths are possible.The second side S2 of the heat exchanger 6 may comprise more than one coaxial flange protrusion arrangement 12, 13. Further, the at least one flange protrusion arrangement 12, 13 may optionally be configured as a fluid interface for a coolant channel connected to a vehicle coolant system outside the drive module 2 (not shown). Thereby the flange protrusion arrangement 12, 13 may have two functions; one function to support the heat exchanger 6 at a second side S2, and an additional function to guide a coolant fluid further in the vehicle coolant system.

Claims

1. A drive module (2) configured for propelling a vehicle (1), the drive module (2) comprising a housing (3), an electric machine (4), a transmission (5) and a heat exchanger (6), wherein the heat exchanger (6) is configured to cool a fluid for cooling the electric machine (4) and / or the transmission (5), wherein a first side (SI) of the heat exchanger (6) is mounted to a fluid interface (7) configured to guide a cooling fluid to and from the heat exchanger (6), characterized in that a second side (S2) of the heat exchanger (6) comprises a heat exchanger flange protrusion (12) mounted coaxially and with axial overlap relative a housing flange protrusion (13) arranged on the inside of the housing (3), such that the heat exchanger (6) is supported at two sides (SI, S2) .

2. The drive module (2) according to claim 1, wherein the heat exchanger flange protrusion (12) and the housing flange protrusion (13) have a cylindrical shape.

3. The drive module (2) according to claim 1 or 2, wherein the housing flange protrusion (13) is arranged coaxially outside the heat exchanger flange protrusion (12).

4. The drive module (2) according to claim 1 or 2, wherein the housing flange protrusion (13) is arranged coaxially inside the heat exchanger flange protrusion (12).

5. The drive module (2) according to claims 1-4, wherein a vibration dampening element (10) is arranged coaxially and axially and at least partially circumferentially between the housing flange protrusion (12) and the heat exchanger flange protrusion (12).

6. The drive module (2) according to claim 5, wherein the vibration dampening element (10) is a rubber o-ring or v-ring.

7. The drive module (2) according to claims 4-5, wherein the heat exchanger flange protrusion (12) comprises a rim portion (9) configured to position the vibration dampening element (10) axially inside the rim portion (9).

8. The drive module (2) according to claims 1-6, wherein a spring element (11) is arranged at an axial end surface of the heat exchanger flange protrusion (12) and coaxially inside or outside the housing flange protrusion (13).

9. A vehicle (1) comprising a drive module (2) according to any one of claims 1-8.