COMPRESSION LIMITER FOR DRIVE BATTERY HOUSING

Abstract

Traction battery assembly, comprising: a first section of a housing; a second section of the casing; a compression limiter, wherein the first section is molded onto the compression limiter; and wherein the compression limiter is annular, and a radially outer surface of the compression limiter is formed with a groove which receives a tongue of the first section such that sections of the compression limiter overlap radially with the tongue.

Description

TECHNICAL AREA

[0001] This disclosure relates generally to a housing for a traction battery, and in particular to a compression limiter integrated into the housing. GENERAL STATE OF THE ART

[0002] Electrified vehicles differ from conventional motor vehicles in that they are selectively powered using one or more electric motors supplied with energy by a traction battery. These electric motors can power the vehicles instead of, or in addition to, an internal combustion engine. Examples of electrified vehicles include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles (FCVs), and battery electric vehicles (BEVs).

[0003] The traction battery is a relatively high-voltage battery that selectively supplies energy to the electric motors and other electrical consumers of the electrified vehicle. The traction battery contains a large number of interconnected battery cells that store energy. The traction battery may include a housing in which the battery cells are contained. SUMMARY

[0004] A traction battery assembly according to an exemplary aspect of the present disclosure includes, among other things, a first section of a housing, a second section of the housing and a compression limiter. The first section is molded onto the compression limiter.

[0005] In a further non-restrictive embodiment of the foregoing assembly, the first section comprises a polymer-based material.

[0006] In a further non-restrictive embodiment of one of the above assemblies, the polymer-based material is reinforced with a glass filler.

[0007] In another non-restrictive embodiment of one of the foregoing assemblies, the second section is a metal or a metal alloy.

[0008] In another non-restrictive embodiment of one of the above assemblies, the second section is a polymer-based material.

[0009] In another non-restrictive embodiment of one of the above assemblies, the first section is a lid and the second section is a tub.

[0010] In a further non-limiting embodiment of one of the foregoing assemblies, the first section is a basin and the second section is a lid. Another non-limiting embodiment of one of the foregoing assemblies includes a mechanical fastener extending through an opening in the compression limiter and securing the first section to the second section. In yet another non-limiting embodiment of one of the foregoing assemblies, the mechanical fastener does not contact the first section when securing the first section to the second section.

[0011] In another non-restrictive embodiment of one of the above assemblies, the compression limiter is a metal or a metal alloy.

[0012] In another non-restrictive embodiment of one of the above assemblies, the compression limiter is an aluminum alloy.

[0013] In a further non-restrictive embodiment of one of the foregoing assemblies, the compression limiter is annular, wherein a radially outer surface of the compression limiter is formed with a groove that receives a tongue of the first section such that sections of the compression limiter overlap radially with the tongue.

[0014] In a further non-restrictive embodiment of one of the foregoing assemblies, the first section comprises a housing section defining at least part of an open area for receiving a battery array, a peripheral flange around a circumference of the housing section, and a plurality of stiffening ribs extending from the housing section to the peripheral flange. The compression limiter is located within the peripheral flange.

[0015] A method according to another exemplary aspect of the present disclosure includes, among other things, fastening a first section of a housing for a traction battery to a second section and limiting the compression of the first section during fastening by means of a compression limiter. The first section is formed onto the compression limiter.

[0016] In another non-restrictive embodiment of the above method, the compression limiter is a metal or a metal alloy, and the first section is polymer-based.

[0017] In a further non-restrictive embodiment of one of the foregoing methods, the second section is a metal or a metal alloy.

[0018] Another non-restrictive embodiment of one of the foregoing methods involves attaching the first section to the second section with a mechanical fastening element extending through an opening in the compression limiter.

[0019] Another non-restrictive embodiment of one of the above methods involves engaging the second section with the mechanical fastening element by means of a thread.

[0020] Another non-restrictive embodiment of one of the above methods involves fastening without the mechanical fastening element touching the first section.

[0021] In a further non-restrictive embodiment of one of the above methods, the compression limiter is annular and the first section is formed on the compression limiter with a tongue of the first section which extends into a groove of the compression limiter such that sections of the compression limiter overlap radially with the tongue. BRIEF DESCRIPTION OF THE FIGURES

[0022] The various features and advantages of the disclosed examples will become apparent to a person skilled in the art from the detailed description. The figures accompanying the detailed description can be briefly described as follows: Fig. Figure 1 illustrates a schematic view of an example powertrain for an electrified vehicle. Fig. Figure 2 illustrates a side view of a drive battery of the powertrain. Fig. 1. Fig. Figure 3 illustrates an extended side view of the drive battery. Fig. 2. Fig. Figure 4 illustrates a perspective view of a cover from a housing of the drive battery. Fig. 2. Fig. Figure 5 illustrates a perspective view of a tub from a housing of the drive battery. Fig. 2. Fig. Figure 6 illustrates a close-up view of area 6 in Fig. 4. Fig. Figure 7 illustrates a bottom view of area 6. Fig. 6. Fig. Figure 8 illustrates a sectional view of a flange of the cover in Fig. 4 along line 8-8 in Fig. 6. Fig. Figure 9 illustrates a sectional view on line 8-8 in Fig. 6 when a mechanical fastener is in an installed position. Fig. Figure 10 illustrates a perspective sectional view of the lid in Fig. 4 on line 10-10 in Fig. 4. Fig. Figure 11 illustrates an underside of the lid made of Fig. 4, which is made of the casing Fig. 2 and Fig. 3 is opposite the provided open area. DETAILED DESCRIPTION

[0023] This disclosure relates to the clamping of a first and second section of a traction battery housing. At least one of the first or the second section contains a compression limiter that allows the first and second sections to remain tightly clamped. If the clamping load were reduced, for example due to plastic creep, the first and second sections could shift relative to each other. This shift could lead to leakage into an interior of the traction battery housing, which could, among other things, allow contaminants to enter the interior.

[0024] Fig. Figure 1 schematically illustrates a powertrain 10 for an electrified vehicle. Although depicted as a hybrid electric vehicle (HEV), it is understood that the concepts described here are not limited to HEVs and could extend to any other electrified vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), fuel cell vehicles, etc.

[0025] The powertrain 10 includes a traction battery 14, which has a variety of battery arrangements 18, an internal combustion engine 20, an electric motor 22, and a generator 24. The electric motor 22 and the generator 24 are types of electric machines. The electric motor 22 and the generator 24 can be separate or have the form of a combined motor-generator.

[0026] In this embodiment, the powertrain 10 is a power-split powertrain that employs a first drive system and a second drive system. The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels 28. The first drive system comprises a combination of the internal combustion engine 20 and the generator 24. The second drive system comprises at least the electric motor 22, the generator 24, and the traction battery 14. The electric motor 22 and the generator 24 are components of an electric drive system of the powertrain 10.

[0027] The internal combustion engine 20 and the generator 24 can be connected by a power transmission unit 30, such as a planetary gear set. Of course, other types of power transmission units, including other gear sets and transmissions, can be used to connect the internal combustion engine 20 to the generator 24. In a non-limiting embodiment, the power transmission unit 30 is a planetary gear set comprising a ring gear 32, a sun gear 34, and a carrier assembly 36.

[0028] The generator 24 can be driven by the internal combustion engine 20 via the power transmission unit 30 to convert kinetic energy into electrical energy. Alternatively, the generator 24 can function as an electric motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft 38 connected to the power transmission unit 30.

[0029] The ring gear 32 of the power transmission unit 30 is connected to a shaft 40, which is connected to the vehicle drive wheels 28 via a second power transmission unit 44. The second power transmission unit 44 may include a gear set comprising a plurality of gears 46. Other power transmission units could be used in other examples.

[0030] The gears 46 transmit the torque from the internal combustion engine 20 to a differential 48 to ultimately provide traction to the vehicle's drive wheels 28. The differential 48 can contain a variety of gears that enable the transmission of torque to the vehicle's drive wheels 28. In this example, the second power transmission unit 44 is mechanically coupled to an axle 50 via the differential 48 to distribute torque to the vehicle's drive wheels 28.

[0031] The electric motor 22 can be selectively used to drive the vehicle's drive wheels 28 by outputting torque to a shaft 52, which is also connected to the second power transmission unit 44. In this embodiment, the electric motor 22 and the generator 24 operate together as part of a regenerative braking system, in which both the electric motor 22 and the generator 24 can be used as electric motors to output torque. For example, the electric motor 22 and the generator 24 can each output electrical energy to recharge cells of the drive battery 14.

[0032] Now with reference to Fig. 2 and Fig. Figure 3 includes the traction battery 14 and a housing 60, which provides an open area 64 in which the battery assemblies 18 are located. The housing 60 could contain one or multiple battery assemblies 18. The traction battery 14, with the housing 60, can be mounted on a vehicle outside of a passenger compartment. The housing protects, among other things, the battery assemblies 18 from environmental pollutants and corrosion.

[0033] The housing 60 comprises at least a first section and a second section. In an exemplary non-limiting embodiment, the first section is a cover 70 of the housing 60 and the second section is a basin 74 of the housing 60. In another embodiment, the first section is the basin 74 of the housing 60 and the second section is the cover 70 of the housing 60.

[0034] The first and second sections are not limited to being a tub or a lid. If the housing 60 were to include a separate side wall, for example, the first or second section could be the separate side wall.

[0035] Referring again to the housing 60, the cover 70 is attached to the basin 74 to provide the open area 64 between them. A variety of mechanical fasteners 78 are used to attach the cover 70 to the basin 74. The interface between the cover 70 and the basin 74 can, for example, be sealed with a polymer gasket.

[0036] Now with reference to Fig. 4 and Fig. 5 with continued reference to Fig. 2 and Fig. 3 The cover 70 includes a housing section 80, a peripheral flange 84, and a plurality of stiffening ribs 88. The housing section 80 provides at least part of the open area 64, which accommodates the battery assembly 18. The peripheral flange 84 extends around a circumference of the housing section 80.

[0037] The cover 70 is made of a polymer-based material, such as a thermoplastic or thermoset material. In some specific examples, the polymer-based material of the cover 70 is a plastic resin suitable for oil pans, such as PA66.

[0038] The material of the cover 70 could further comprise a reinforcing additive, such as a glass filler or carbon fiber filler. The material of the cover 70 could instead or additionally comprise a conductive filler material if required for the electromagnetic compatibility of the cover 70. The cover 70 can be configured with channels to allow heat dissipation from the drive battery 14. In some exemplary embodiments, the cover 70 could include such channels formed in an outwardly facing surface of the cover 70 to provide fins or heat sinks for heat dissipation. Fan-driven air, ram air, or some other type of flow could be moved through the channels over the fins to dissipate thermal energy from the cover 70.

[0039] Because the lid 70 is polymer-based, it is lighter than a lid of similar size made of metal or a metal alloy. Manufacturing the lid 70, or any other section of the housing 60, from a polymer-based material can therefore reduce the weight compared to a housing made of metal or a metal alloy. The polymer-based material can also save costs compared to materials that would require an e-coating.

[0040] The housing 74 comprises a housing section 90, a peripheral flange 94, and a plurality of stiffening ribs 98 extending from the housing section 90 to the peripheral flange 94. The housing section 90 provides a remaining portion of the open area 64, which accommodates the battery assembly 18. The peripheral flange 94 extends around a circumference of the housing section 90.

[0041] The exemplary tub 74 is made of a metal or a metal alloy. In one specific exemplary embodiment, the tub 74 is made of aluminum. In another exemplary embodiment, the tub 74 is made of a polymer-based material that is harder than the polymer-based material of the lid 70.

[0042] In the exemplary non-restrictive embodiment, the plurality of mechanical fastening elements 78 are threaded fastening elements, such as M6 screws, which engage with respective threaded bores 104 in the tub 74. When they are in the installed position from Fig. 2 are tightened, the multitude of mechanical fastening elements 78 clamp the peripheral flange 84 of the cover 70 against the peripheral flange 94 of the tub 74.

[0043] Since the cover 70 is made of a relatively soft polymer-based material, applying a stress load to the flange 84 could compress the flange material and, over time, lead to creep deformation of the polymer-based material. This creep deformation could cause the mechanical fastener 78 to loosen. The loose mechanical fastener 78 could allow movement of the cover 70 relative to the basin 74, which could then, among other things, create a passage through the interface. Contaminants could then unintentionally move through this passage into the open area 64.

[0044] To address the potential loosening of the mechanical fasteners 78 due to compression of the flange 84, the exemplary flange 84 is formed onto a plurality of compression limiters 110, which are distributed around the circumference of the cover 70 and held in the flange 84. In this example, one of the compression limiters 110 is used in conjunction with each of the mechanical fasteners 78 that secure the cover 70 to the pan 74. In this non-restrictive embodiment, the compression limiters 110 are a metal or a metal-based material. For example, the compression limiters 110 could be a galvanized K-alloy.

[0045] When one of the mechanical fasteners 78 is tightened in one of the threaded bores 104, the compression limiter 110 is clamped between a head 114 of the mechanical fastener 78 and the flange 94 of the pan 74. Thus, the compression limiter 110 is clamped instead of the flange 84 of the cover 70.

[0046] The compression limiter 110 is made of a material that is essentially incompressible relative to the flange 84. Thus, the mechanical fastener 78 can remain in close engagement with the threaded bore 104 of the pan and prevent movement of the cover 70 relative to the pan 74. In some examples, the compression limiter 110 is made of a metal or metal alloy that can also provide a section of a grounding path for the drive battery 14 in the open area 64 to an area outside the housing 60.

[0047] With reference to Fig. 6-9, the compression limiter 110 is a ring and provides an opening 118 that receives a shaft 122 of the mechanical fastening element 78. In this example, the ring 118 does not include any threads.

[0048] In this exemplary embodiment, the head 114 of the mechanical fastening element 78 has a diameter D H ( Fig. 9), and one side of the compression limiter 110, which has an interface with the head 114, has a diameter D CL ( Fig. 8) on. The compression limiter 110 is dimensioned such that the diameter D CL larger than the diameter D H is. Measuring the diameter D CLThe compression limiter 110 is designed in this way to ensure that the head 114 is clamped against the compression limiter 110 without being clamped directly against the flange 84. That is, the head 114 and the remaining sections of the mechanical fastener 78 do not touch any part of the flange 84 when the flange 84 is clamped against the flange 94 of the pan 74. Oversized the compression limiter 110 relative to the head 114 in this way can provide a suitable bearing surface to maintain a residual torque that results in a clamping load sufficient to seal the flange 84.

[0049] In other examples, the diameter D H of the head 114 larger than the diameter D CL of the compression limiter 110.

[0050] To secure the compression limiter 110 in the flange 94, the flange 94 is molded onto the compression limiter 110. The compression limiter 110 could, for example, be placed in a mold cavity that corresponds to the desired dimensions of the cover 70. Molten polymer material is injected into the mold cavity. The polymer material then hardens, which holds the compression limiter 110 in the flange 94.

[0051] In this example, a radially outer surface 130 of the compression limiter 110 is formed with a groove 134 that receives a tongue 138 of the flange 84. Axial end sections 142a and 142b of the compression limiter 110 thus overlap radially with the tongue 138. This overlap of the axial end sections 142a and 142b with the tongue 138 prevents the compression limiter 110 from retracting axially from the flange 84. In particular, the oversizing of the compression limiter 110 relative to the head 114, as described above, provides radial space within the compression limiter 110 to receive the tongue 138, while the tongue 138 remains radially spaced from the mechanical fastening element 78. This ensures that the tongue 138 does not result in a relatively soft connection point.This means that the compression limiter 110 can radially accommodate the tongue 138, while a radial portion of the compression limiter 110 remains uninterrupted by the tongue 138. The radial portion uninterrupted by the tongue 138 can be clamped tightly between the head 114 and the flange 94 of the basin 74 to provide a relatively rigid connection.

[0052] In this example, a region of the flange 84 surrounding the compression limiter 110 is raised relative to other regions of the flange 84. This provides a localized area around the compression limiter 110 that is thicker than the other regions of the flange 84, which can reinforce the flange 84 in the region of the compression limiter 110.

[0053] The exemplary compression limiter 110 is shown in the illustration held in the flange 84 of the cover 70. In another example, the compression limiter 110 could be held in the flange 94 of the basin 74. In such an example, the flange 84 would be in Fig. 6 a flange of the tub 74 instead of the flange 84 of the lid 70.

[0054] Positioning the compression limiter 110 within the tub 74 could be advantageous if the tub 74 were made, for example, of a polymer-based material or of another material that is softer relative to the material of the lid 70. The tub 74 could, for example, incorporate the compression limiter 110 if the tub 74 were polymer-based and the lid were a metal or a metal alloy.

[0055] With reference to Fig. 10 with reference to Fig. 2 and Fig. 3 The multiple stiffening ribs 88 now extend from the housing section 80 to the peripheral flange 84. The stiffening ribs 88 can dampen a bending moment that excites movement of the peripheral flange 84 relative to the housing section 80. A bottom surface 160 of the flange 84 of the cover 70 is sealed against the flange 94 of the basin 74 when the mechanical fasteners 78 are in the installed position. Fig. 2 are tightened. The stiffening ribs 88 can provide a consistently sealed interface between the underside 160 and the flange 94. The stiffening ribs 98 of the tub 74 provide similar support for the flange 94.

[0056] The structural support provided by the stiffening ribs 98 can additionally allow larger bending radii at the corners 164 and 168 of the lid 70 than would be possible without the stiffening ribs 98. The larger bending radii can reduce the overall packaging space required for the housing 60. The stiffening ribs 98 of the tub 74 can also allow the use of larger bending radii in the tub 74.

[0057] With reference to Fig. 11 with reference to Fig. 2 and Fig. 3. A network 172 made of ribs 176 can now be integrated into the cover 70 for additional structural support. In this example, the ribs 176 extend into the open area 64 of the housing 60. Other ribs 180 can be positioned at the corners 168 to add additional structural support for the corners 168.

[0058] Features of some of the disclosed examples include securely joining a relatively soft section of a traction battery housing to a relatively hard section, and preventing the joint from compressing the relatively soft section by overmolding a compression limiter into the relatively soft section.

[0059] The foregoing description is more illustrative than restrictive. A person skilled in the art may deduce variations and modifications of the disclosed examples that do not necessarily deviate from the core of this disclosure. Therefore, the scope of protection afforded by this disclosure can only be determined by reading the following patent claims.

Claims

[1] Traction battery assembly comprising: a first portion of a housing; a second portion of the housing; a compression limiter, wherein the first portion is molded onto the compression limiter; and wherein the compression limiter is annular, and a radially outer surface of the compression limiter is formed with a groove that receives a tongue of the first portion such that portions of the compression limiter radially overlap with the tongue. [2] The assembly of claim 1, wherein the first portion comprises a polymer-based material, and optionally, wherein the polymer-based material is reinforced with a glass filler. [3] The assembly of claim 2, wherein the second portion is a metal or a metal alloy, or wherein the second portion is a polymer-based material. [4] The assembly of claim 1, wherein the first portion is a lid and the second portion is a tray. [5] The assembly of claim 1, wherein the first portion is a tray and the second portion is a lid. [6] The assembly of claim 1, further comprising a mechanical fastener extending through an opening in the compression limiter and securing the first portion to the second portion, and optionally, wherein the mechanical fastener does not contact the first portion when securing the first portion to the second portion. [7] The assembly of claim 1, wherein the compression limiter is a metal or a metal alloy, and optionally, wherein the compression limiter is an aluminum alloy. [8] The assembly of claim 1, wherein the first portion includes a housing portion defining at least a portion of an open area for receiving a battery pack, a peripheral flange around a perimeter of the housing portion, and a plurality of stiffening ribs extending from the housing portion to the peripheral flange, the compression limiter being located within the peripheral flange. [9] Method comprising: Attaching a first portion of a housing for a traction battery to a second portion, and limiting compression of the first portion during attachment using a compression limiter, the first portion being overmolded onto the compression limiter, further comprising attaching the first portion to the second portion with a mechanical fastener extending through an opening in the compression limiter, the compression limiter being annular, and the first portion being overmolded onto the compression limiter with a tongue of the first portion extending into a groove of the compression limiter such that portions of the compression limiter radially overlap with the tongue. [10] The method of claim 9, wherein the compression limiter is a metal or a metal alloy, and the first portion is polymer-based, and optionally, wherein the second portion is a metal or a metal alloy. [11] The method of claim 9, further comprising threadingly engaging the second portion with the mechanical fastener. [12] The method of claim 9, further comprising securing without the mechanical fastener contacting the first portion.

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