KR20220122089A - Frame for battery module of electric vehicle with adhering different kind of materials - Google Patents

Abstract

The present invention relates to an electric vehicle battery module frame in which a plastic material and a metal material are heterojunctioned. Specifically, the present invention relates to an electric vehicle battery module frame, which can stably support and protect an electric vehicle battery module due to its excellent dimensional accuracy and strength, can improve battery performance by stably maintaining the temperature of the electric vehicle battery module through excellent heat dissipation effects, is advantageous for light weight, and can reduce manufacturing costs.

Description

Heterojunctional electric vehicle battery module frame {Frame for battery module of electric vehicle with adhering different kind of materials}

The present invention relates to an electric vehicle battery module frame in which a plastic material and a metal material are heterogeneously bonded. Specifically, the present invention can stably support and protect an electric vehicle battery module due to excellent dimensional precision and strength, and can improve battery performance by stably maintaining the temperature of electric vehicle battery module through excellent heat dissipation effect, and reduce weight It relates to an electric vehicle battery module frame that can be advantageous and reduce manufacturing costs.

In an electric vehicle, the stability and performance of the battery are the most important factors that determine the marketability of an electric vehicle, such as the driving range. In particular, the performance of the battery is greatly affected by the ambient temperature, and in general, proper performance can be realized only when the battery is maintained at a temperature of 0 to 40°C.

However, the battery generates heat during charging or discharging (operation), which may increase the ambient temperature and deteriorate battery performance. In addition, since it is necessary to protect the battery from the surrounding shock such as an accident or the vibration of the electric vehicle itself, a frame for stably supporting and protecting the battery by mounting the battery is used.

The conventional battery module frame may be made in the form of a metal box capable of accommodating a plurality of battery cells constituting the battery module, and such a metal frame may stably protect the battery cells from external impact with high mechanical strength. It can be protected from the battery, and the heat emitted from the battery cells can be quickly dissipated out of the battery module due to its high thermal conductivity.

In general, in order for an electric vehicle to travel the same mileage as an internal combustion engine vehicle, a battery of about 360 to 400 kg is required, where the weight of the battery module frame is about 10 to 20%. Therefore, if the weight of the battery module frame can be reduced, more battery cells can be mounted, which can lead to an increase in the mileage.

Therefore, the conventional metal battery module frame is made of an aluminum material with a specific gravity of 2.7 g/cm3 from a conventional iron material having a specific gravity of 7.8 g/cm3 to a lightweight metal for weight reduction, in particular, a high tensile strength of 230 MPa or more and a high tensile strength of -30℃. Although it is changing to a 6,000 series aluminum alloy that does not cause brittle fracture even in a low-temperature environment, these aluminum materials are generally difficult to form and have low productivity, and since they are manufactured through an extrusion process, separate chamfering, that is, There is a problem in that the processing cost increases due to an additional process such as processing the edge portion to be inclined or rounded.

In particular, the electric vehicle battery module frame must form a precisely standardized space for accommodating a predetermined number of battery cells in order to stably protect the battery module from the impact caused by the vibration of the electric vehicle, the separation distance between the battery cells and the battery pack It is necessary to ensure very precise dimensional stability such as a position in which it is placed, for example, a tolerance of ±0.3 mm, but a battery module frame made of a metal material, which is difficult to form and process in the prior art, has a problem in that it is difficult to sufficiently secure such dimensional accuracy.

Recently, there is a trend to reduce the weight by applying a plastic material that is lighter than an aluminum material, but in general, the thermal conductivity of plastic is much lower than that of a metal material, and there is a problem in that the heat dissipation property is lowered. Although additives that can be improved are used, these materials are expensive and the heat dissipation performance is still insufficient compared to the existing metal materials.

On the other hand, it can be considered to mix aluminum and plastic materials, but in this case, it is difficult to bond different materials, so that it is difficult to secure the dimensional accuracy and strength of the battery module frame.

Therefore, it is possible to stably support and protect the electric vehicle battery module due to its excellent dimensional precision and strength, and it is possible to improve the battery performance by stably maintaining the temperature of the electric vehicle battery module through excellent heat dissipation effect, and it is advantageous for light weight and manufacturing There is an urgent need for an electric vehicle battery module frame that can reduce costs.

An object of the present invention is to provide an electric vehicle battery module frame that can stably support and protect an electric vehicle battery module with excellent dimensional accuracy and strength.

Another object of the present invention is to provide an electric vehicle battery module frame capable of improving battery performance by stably maintaining the temperature of an electric vehicle battery module through an excellent heat dissipation effect.

Furthermore, an object of the present invention is to provide an electric vehicle battery module frame that is advantageous in weight reduction and can reduce manufacturing costs.

In order to solve the above problems, the present invention,

An electric vehicle battery module frame, comprising: an upper housing having an open lower surface and having an empty space in which a battery module can be mounted; and a lower plate coupled to the open lower surface of the upper housing, wherein the upper housing is plastic The lower plate may be made of a material, and the lower plate may be made of a metal material or a thermally conductive plastic material. The lower plate has protrusions at left and right ends coupled to the upper housing, respectively, and the upper housing has the protrusions at the left and right ends. Provided is an electric vehicle battery module frame, each provided with grooves into which are respectively inserted.

Here, the protrusion is formed on the side surface of the lower plate, and the ratio (L _ratio ) of the length (L _i ) of the protrusion to the overall length (L _o ) of the lower plate defined by Equation 1 below is 5 to 60 %ego,

[Equation 1]

L _ratio =L _i /L _o ×100

It provides an electric vehicle battery module frame, characterized in that the ratio of the thickness (T _i ) of the protrusion to the thickness (T _o ) of the lower plate defined by Equation 2 below is 15 to 45%.

[Equation 2]

T _ratio =T _i /T _o ×100

On the other hand, the protrusion is formed on the upper surface of the lower plate, and the ratio (H) of the height (H _i ) of the protrusion and the groove to the overall height (H _o ) of the side surface of the upper housing defined by Equation 3 below. _ratio ) is 5 to 60%,

[Equation 3]

H _ratio =H _i /H _o ×100

The ratio (W _ratio ) of the width (W _i ) of the protrusion and the groove portion to the width (W _o ) of the side surface of the upper housing defined by Equation 4 below is 15 to 45%, characterized in that the electric vehicle battery module frame provides

[Equation 4]

W _ratio =W _i /W _o ×100

In addition, there is provided an electric vehicle battery module frame manufactured by injecting the lower plate into the injection molding machine mold and injecting the plastic material forming the upper housing into the injection molding machine mold in a molten state.

And, the protrusion is provided with one or more perforated holes, and the ratio of the total cross-sectional area of the perforated hole to the surface area of the protrusion provided with the perforated hole is 10 to 70%, providing an electric vehicle battery module frame do.

Furthermore, the surface roughness (Ra) of the bonding surface of the protrusion is 6 or more, the surface roughness (Rmax) is 25S or more, and the surface roughness (Rz) is 25Z or more, It provides an electric vehicle battery module frame.

In addition, it provides an electric vehicle battery module frame, characterized in that the adhesive is applied to the bonding surface of the protrusion.

On the other hand, the lower plate provides an electric vehicle battery module frame having a thermal conductivity of 0.5 to 1,000 W/m·K.

In addition, the upper housing has a tensile strength of 30 to 500 MPa according to the standard ASTM D638, a flexural strength of 50 to 500 MPa according to the standard ASTM D790, and a burning time according to the standard UL-94 V test of 60 seconds or less, The thermal deformation temperature according to the standard ASTM D648 is 50 to 300 °C, the Izod impact strength at -30 °C according to the standard ASTM D256 is 1 kJ/m2 or more, and the shrinkage according to the standard ASTM D955 is 0.03 to 3% It provides an electric vehicle battery module frame, characterized in that.

Here, the plastic material forming the upper housing is made of polyamide (PA), modified polyphenylene oxide (mPPO), polybutyl terephthalate (PBT), polyethyl terephthalate (PET), and polycarbonate (PC). It provides an electric vehicle battery module frame comprising one or more engineering plastics selected from the group and one or more reinforcing additives selected from the group consisting of glass fibers, carbon fibers, aramid fibers, carbon nanotubes and graphene.

In addition, the content of the reinforcing additive provides an electric vehicle battery module frame, characterized in that 5 to 150 parts by weight based on 100 parts by weight of the engineering plastic.

On the other hand, it provides an electric vehicle battery module frame, characterized in that the cooling plate is formed a refrigerant flow path through the lower portion of the lower plate is disposed.

Here, the ratio of the plane cross-sectional area of the refrigerant passage to the total planar cross-sectional area measured in the cross-section in which the plane cross-sectional area of the refrigerant passage is maximized among the cross-sections of the cooling plate is 50% or more.

The electric vehicle battery module frame according to the present invention has improved dimensional accuracy and strength through a precisely controlled heterojunction structure of an upper housing made of a specific plastic material and a lower plate having thermal conductivity above a certain level, thereby stably supporting an electric vehicle battery module. and, at the same time, exhibits an excellent effect of improving battery performance by stably maintaining the temperature of the electric vehicle battery module through an excellent heat dissipation effect.

In addition, the electric vehicle battery module frame according to the present invention exhibits an excellent effect in that it is advantageous to light weight and the manufacturing cost can be reduced through a specific plastic material.

1 schematically shows a perspective view of an embodiment of an electric vehicle battery module frame according to the present invention.
2 schematically shows a perspective view of another embodiment of an electric vehicle battery module frame according to the present invention.
3 is an enlarged view of the heterojunction structure shown in FIG. 1A.
FIG. 4 is an enlarged view of the heterojunction structure shown in FIG. 1B.
5 shows one embodiment of the heterojunction site in FIGS. 3 and 4 .
6 schematically shows the structure of the heterojunction specimen used in Examples.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art. Like reference numbers refer to like elements throughout.

1 schematically shows a perspective view of one embodiment of an electric vehicle battery module frame according to the present invention, and FIG. 2 schematically shows a perspective view of another embodiment of an electric vehicle battery module frame according to the present invention. will be.

As shown in FIG. 1 , the electric vehicle battery module frame 100 according to the present invention has an open lower surface and an empty space in which a battery module including a plurality of battery cells can be mounted, and the battery module It may include a 'C'-shaped upper housing 110 with open front and back sides so that it can be inserted, and a lower plate 120 coupled to the open lower surface of the upper housing 110 .

In addition, as shown in FIG. 2 , a cooling plate 300 having a refrigerant flow path 310 through which a refrigerant such as cooling water may flow may be additionally disposed under the lower plate 120 .

The cooling plate 300 has a refrigerant passage 310 through which a refrigerant such as cooling water can flow therein, and may be made of a metal material such as aluminum. The lower plate 120 is made of a material having a higher thermal conductivity than the upper housing 110, so that most of the heat energy from the battery module is quickly absorbed and transferred to the cooling plate 300, thereby dissipating heat. have.

Specifically, the ratio of the plane cross-sectional area of the refrigerant passage 310 to the total cross-sectional area of the refrigerant passage 310 measured in the cross-section at which the plane cross-sectional area of the refrigerant passage 310 is maximized among the cross-sections of the cooling plate 300 is about 50% or more, preferably may be about 70% or more, and accordingly, the heat dissipation ratio, that is, the ratio of the heating value of the cooling plate 300 to the total heating value of the battery module frame may be 70% or more, preferably 80% or more, and the cross-sectional ratio is 50 % or when the heat dissipation ratio is less than 70%, the rapid heat energy absorption of the lower plate 300 and thus heat dissipation characteristics may be insufficient.

Meanwhile, the upper housing 110 may be made of a plastic material. Since the upper housing 110 is made of a plastic material, unlike a conventional metal frame, injection molding is possible, so dimensional accuracy is greatly improved, and thus, through a closer adhesion between the inner wall of the upper housing 110 and the battery module By minimizing the empty space between them, it is possible to more stably support and protect the battery module even when the electric vehicle vibrates, and it is possible to prevent the heat dissipation effect from being deteriorated by the empty space.

Specifically, the plastic material is polyamide (PA6, PA66), modified polyphenylene oxide (mPPO), polybutyl terephthalate (PBT), polyethyl terephthalate (PET), engineering plastics such as polycarbonate (PC) , Preferably, a reinforcing additive such as glass fiber, carbon fiber, aramid fiber, carbon nanotube, graphene, etc., preferably glass fiber, may be added to the engineering plastic of polyamide (PA).

Here, the content of the reinforcing additive may be 5 to 150 parts by weight, preferably 20 to 120 parts by weight, based on 100 parts by weight of the engineering plastic. When the content of the reinforcing additive is less than 5 parts by weight, the desired mechanical properties such as tensile strength and flexural strength of the upper housing 110 cannot be satisfied, whereas when it exceeds 150 parts by weight, to manufacture the upper housing 110 During injection for injection, productivity is reduced due to severe abrasion of screws and molds of the injection machine, the weight of the upper housing 110 is increased due to the increase in specific gravity of the plastic material, and some mechanical properties such as impact strength are lowered. can

The plastic material has excellent mechanical strength for protecting the battery module from external impact, for example, the tensile strength measured under a load of 20 kN at a rate of 5 mm/min according to the standard ASTM D638 of 30 to 500 MPa, preferably is 50 to 400 MPa, more preferably 70 to 300 MPa, and the flexural strength measured by a 3-point flexural test under a load of 20 kN at a speed of 5 mm/min according to standard ASTM D790 is 50 to 500 MPa, preferably preferably 80 to 400 MPa, more preferably 130 to 350 MPa.

Here, if the tensile strength of the plastic material is less than 30 MPa, the minimum mechanical properties for protecting the battery module from external impact may not be satisfied, whereas if it exceeds 500 MPa, injection processability is lowered by an excessive amount of additives, and Manufacturing costs may increase unnecessarily.

In addition, if the flexural strength of the plastic material is less than 50 MPa, it may be difficult to withstand mechanical stress due to thermal expansion of the battery module, whereas if it exceeds 500 MPa, injection processability is reduced due to excessive additives and manufacturing cost is increased unnecessarily. can

On the other hand, the plastic material has excellent flame retardancy that can withstand fire, for example, a flame of 20 mm in length according to the standard UL-94 V test for 10 seconds, and then the combustion time is 60 seconds or less, preferably the combustion time This is 30 seconds or less, and more preferably, the combustion time after secondary flame contact for an additional 10 seconds may be 90 seconds or less, preferably the combustion time may be 60 seconds or less, and a high heat deflection temperature that can withstand the heat emitted from the battery module , For example, the thermal deformation temperature, which is the temperature when the specimen sags 0.254 mm while heating the oil at a rate of 120 ° C / hr after preheating for 5 minutes by immersing the specimen in oil according to the standard ASTM D648, is 50 to 300 ° C., preferably Preferably it may be 80 to 270 ℃, more preferably 100 to 250 ℃.

Here, when the thermal deformation temperature of the plastic material is less than 50°C, deformation such as distortion of the upper housing 110 may occur due to heat generated in the battery module, whereas when it exceeds 300°C, the melting point is too high for compounding and Injection processability may be greatly reduced and manufacturing cost may increase unnecessarily.

In addition, the plastic material has excellent low-temperature impact properties that can be used even in a low-temperature environment, for example, Izod, which is measured when the specimen is cut by striking with a hammer after leaving it for at least 30 minutes in a chamber at -30°C according to standard ASTM D256 (Izod) the impact strength may be 1 kJ/m 2 or more, preferably 3 kJ/m 2 or more, more preferably 5 kJ/m 2 or more.

Here, when the Izod impact strength of the plastic material is less than 1 kJ/m2, the battery module cannot be properly protected, such as the battery module being damaged by a crash accident in a low-temperature environment such as winter. On the other hand, the higher the low-temperature impact strength, the better, but it is preferable to maintain an appropriate level in trade-off with tensile strength, flexural strength, flame retardancy, and the like.

In addition, the plastic material has a shrinkage rate showing excellent dimensional accuracy, for example, the shrinkage rate measured by injection into a mold at a temperature of 23±2° C. and a humidity of 50±5% according to the standard ASTM D955 and separating after 24±0.5 hours is 0.03 to 3%, preferably 0.05 to 2%, more preferably 0.1 to 1%, and when the shrinkage ratio is less than 0.03%, properties such as injection productivity are deteriorated due to an excessive amount of additive, whereas when it is more than 3% It is difficult to satisfy the dimensional accuracy of ±0.3 mm.

The upper housing 110 may be formed in a U-shape with the front and back sides open so that the battery module can be inserted, but the front and back sides are formed of a front plate and a rear plate made of the same plastic material as the upper housing 110 . can cover

The lower plate 120 may be made of a metal material having high thermal conductivity, such as aluminum, copper, iron, etc., but polyamide (PA), modified polyphenylene oxide (mPPO), polybutyl terephthalate (PBT), polyethyl Engineering plastics such as terephthalate (PET), polycarbonate (PC), preferably polyamide (PA), carbon fibers, carbon nanotubes, graphene, aluminum nitride, boron nitride ), may be made of a thermally conductive plastic material filled with a thermally conductive additive including a metal powder such as silicon carbide or aluminum.

The thermal conductivity of the lower plate 120 is 0.5 to 1,000 W/m·K, preferably 1 to 600 W when made of a metal material or a plastic material in order to secure the heat dissipation characteristics of the battery module frame. /m·K, more preferably 2 to 300 W/m·K may be made of a material.

When the thermal conductivity of the material forming the lower plate 120 is less than 0.5 W/m·K, the heat dissipation property is insufficient and degradation of the battery module may be induced, whereas when it exceeds 1,000 W/m·K, excessive The addition of the thermally conductive additive may cause a problem in that processability is lowered and manufacturing cost is unnecessarily increased.

Specifically, when the lower plate 120 is formed of a plastic material, the content of the thermal conductive additive may be 5 to 150 parts by weight, preferably 20 to 120 parts by weight, based on 100 parts by weight of the engineering plastic. Here, when the content of the thermal conductivity additive is less than 5 parts by weight, it is difficult to implement thermal conductivity of 0.5 W/m·K or more, and when it is more than 150 parts by weight, the specific gravity of the plastic material exceeds 2 g/cm 3 , so the battery module frame weight reduction may be insufficient.

The upper housing 110 may be combined with a lower plate 120 made of a material different from that of the upper housing 110 by heterojunction. For example, the upper housing 110 and the lower plate 120 may It can be joined by insert injection molding. That is, the lower plate 120 is manufactured in advance and inserted into the mold of the injection machine, and then the plastic material of the upper housing 110 is melted/injected into the mold and injected to form a box-shaped structure as a whole.

Specifically, as shown in FIG. 1 , protrusions are provided at left and right ends at which the lower plate 120 is coupled to the upper housing 110 , and the protrusions are respectively provided at left and right ends of the upper housing 110 . Each of the grooves to be inserted may be provided, and the protrusion is formed on the side surface of the lower plate 120 as shown in FIG. 1A or is formed on the upper surface of the lower plate 120 as shown in FIG. 1B . can be

FIG. 3 is an enlarged view of the heterojunction structure illustrated in FIG. 1A , and FIG. 4 is an enlarged view illustrating the heterojunction structure illustrated in FIG. 1B .

1A and 3 , when the protrusion is formed on the side surface of the lower plate 120 , the protrusion is compared to the overall length L _o of the lower plate 120 defined by Equation 1 below. The length (L _i ) of the ratio (L _ratio ) may be adjusted to 5 to 60%, preferably 10 to 50%, more preferably 15 to 45%.

[Equation 1]

L _ratio =L _i /L _o ×100

In addition, the ratio (T _ratio ) of the thickness (T _i ) of the protrusion to the thickness (T _o ) of the lower plate 120 defined by Equation 2 below is 15 to 45%, preferably 20 to 40%, More preferably, it may be adjusted to 25 to 35%.

[Equation 2]

T _ratio =T _i /T _o ×100

Meanwhile, as shown in FIGS. 1B and 4 , when the protrusion is formed on the upper surface of the lower plate 120 , the total height H of the side surface of the upper housing 110 defined by Equation 3 below _o ) to the height (H _i ) of the protrusion and the groove portion (H _ratio ) may be adjusted to 5 to 60%, preferably 10 to 50%, more preferably 15 to 45%.

[Equation 3]

H _ratio =H _i /H _o ×100

In addition, the ratio (W _ratio ) of the width (W _o ) of the side surface of the upper housing 110 defined by Equation 4 below to the width (W _i ) of the protrusion and the groove portion is 15 to 45%, preferably 20 to 40%, more preferably 25 to 35%.

[Equation 4]

W _ratio =W _i /W _o ×100

Here, when the length ratio (L _ratio ) or the height ratio (H _ratio ) is less than 5%, the bonding strength at the heterojunction site is greatly reduced, whereas when it exceeds 60%, the heat release rate of the lower plate 120 is can be greatly reduced. On the other hand, when the thickness ratio (T _ratio ) or the width ratio (W _ratio ) is less than 15%, injection moldability is greatly reduced, whereas when it exceeds 45%, the bonding strength in the heterojunction region may be greatly reduced.

5 shows one embodiment of the heterojunction site in FIGS. 3 and 4 .

As shown in FIG. 5 , one or more perforated holes 121 may be provided in the protrusion at the joint portion of the upper housing 110 and the lower plate 120 , and the cross-sectional shape of the perforated hole 121 . Silver may have various shapes such as a circle, an ellipse, an n-shaped, and the like, and during the insert injection process, the plastic material forming the upper housing 110 fills the perforated hole 121 provided in the protrusion of the lower plate 120 . By injection, the upper housing 110 and the lower plate 120 may be more firmly coupled.

Specifically, the ratio of the cross-sectional area of the entire perforated hole 121 to the surface area of the protrusion provided with the perforated hole 121 is 10 to 70%, preferably 20 to 60%, more preferably 30 to 50%. It can be %. Here, when the area ratio is less than 10%, the bonding force at the bonding portion between the upper housing 110 and the lower plate 120 may be insufficient, whereas when the area ratio is more than 70%, the heat dissipation rate of the lower plate 120 is may be insufficient.

Furthermore, in order to further improve the bonding force at the heterojunction portion between the upper housing 110 and the lower plate 120, the protrusion and the protrusion and the protrusion by forming irregularities or the like on the bonding surface of the groove portion or by roughening the surface. The joint area of the groove portion can be increased.

Specifically, the surface roughness (Ra) representing the centerline surface roughness of the joint surface of the protrusion of the lower plate 120 is 6 or more, preferably 25 or more, and the surface roughness (Rmax) representing the maximum height of the concave-convex structure is 25S or more , preferably 100S or more, the 10-point average roughness (Rz) may be 25Z or more, preferably 100Z or more.

Meanwhile, in order to further improve adhesion between the protrusion of the lower plate 120 and the groove of the upper housing 110 , an adhesive may be additionally applied to the bonding surface of the protrusion.

The adhesive is a phenol-based, epoxy-based, acrylic-based, urethane-based, urea-based, melamine-based, unsaturated/saturated polyester-based, vinyl acetate-based, polyvinyl alcohol-based, vinyl chloride-based, polyvinylacetal-based, polyamide-based adhesive. can be used

Here, thermosetting adhesives such as phenolic and epoxy adhesives are suitable to cure within 80°C/30 minutes, and other room temperature curing adhesives are suitable to be cured at 23°C/96 hours or less. because it can

In addition, when the protrusion of the lower plate 120 and the groove of the upper housing 110 are joined only with the adhesive, the joint portion has a tensile strength measured under a load of 20 kN at a rate of 5 mm/min according to the standard ASTM D638. is 30 MPa or more, preferably 40 MPa or more, more preferably 50 MPa or more, and the flexural strength measured by a 3-point flexural test under a load of 20 kN at a speed of 5 mm/min according to standard ASTM D790 is 30 MPa or more, the bonding strength measured according to the standard ISO 4587 may be 3 MPa or more, preferably 5 MPa or more, and more preferably 7 MPa or more.

[Example]

1. Preparation example

A battery module frame was manufactured with the configuration shown in Table 1 and FIG. 6 below.

L _ratio (%) T _ratio (%) Perforated hole area ratio (%) glue



line
city
Yes One 20 40 30 - 2 20 20 30 - 3 20 40 50 - 4 20 20 50 - 5 40 40 30 - 6 40 20 30 - 7 40 40 50 - 8 40 20 50 - 9 40 20 50 Epoxy 10 40 20 50 urethane

rain
school
Yes One 10 40 30 - 2 60 40 30 - 3 20 40 10 - 4 20 40 80 - 5 20 10 30 - 6 20 80 30 -

2. Physical property evaluation

1) Tensile strength evaluation

According to the standard ASTM D638, the tensile strength of the joint was measured under a load of 20 kN at a speed of 5 mm/min.

2) Flexural strength evaluation

According to the standard ASTM D790, the flexural strength of the joint was measured by a 3-point flexural test under a load of 20 kN at a speed of 5 mm/min.

3) Evaluation of heat release rate and injection moldability

The heat dissipation rate of the battery module frame was evaluated by measuring the temperature of the battery cells over time by combining the battery cells with the battery module frame and applying power. evaluated. The evaluation result is 1: very poor, 3: average, and 5: very good.

The physical property evaluation results are as shown in Table 2 below.

Tensile strength (MPa) Flexural strength (MPa) heat release rate injection moldability



line
city
Yes One 49 85 3 3 2 50 92 3 3 3 55 99 3 3 4 62 102 3 3 5 63 93 2 3 6 57 96 2 3 7 62 102 2 3 8 64 114 2 3 9 69 124 2 3 10 66 118 2 3

rain
school
Yes One 22 39 4 3 2 50 95 One One 3 28 42 3 3 4 58 99 2 One 5 57 106 3 One 6 21 33 3 4

As shown in Table 2, an embodiment in which the ratio of length (Lratio) and thickness ratio (Tratio) of the protrusion of the lower plate and the groove of the upper housing is appropriately adjusted and the ratio of the total cross-sectional area of the perforated hole provided in the protrusion is appropriately adjusted It was confirmed that the battery module frames of 1 to 10 exhibit excellent tensile and flexural strength at the joint, and at the same time have excellent heat dissipation rate through improved dimensional precision, and excellent injection moldability at the joint.

On the other hand, in the battery module frames of Comparative Examples 1 and 5, the length ratio (Lratio) or thickness ratio (Tratio) of the protrusion provided on the lower plate was less than the standard, so the tensile strength of the joint was lowered or the injection moldability was lowered, and the injection moldability was lowered. In the battery module frames of 2 and 6, the length ratio (Lratio) or thickness ratio (Tratio) of the protrusion provided in the lower plate exceeds the standard, and the heat release rate of the lower plate and the injection moldability of the joint portion are greatly reduced, or the tensile strength and flexural strength was found to be lowered.

In addition, in the battery module frame of Comparative Example 3, the tensile strength and flexural strength were greatly reduced due to the ratio of the total cross-sectional area of the perforated holes provided in the protrusion of the lower plate being less than the standard, whereas the battery module frame of Comparative Example 4 had the protrusion of the lower plate. It was confirmed that the ratio of the total cross-sectional area of the provided perforated holes exceeded the standard, and the heat release rate and injection moldability of the joint were lowered.

Although the present specification has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims described below. will be able to carry out Therefore, if the modified implementation basically includes the elements of the claims of the present invention, all of them should be considered to be included in the technical scope of the present invention.

110: upper housing 120: lower plate
200: battery module 300: cooling plate
310: refrigerant flow path

Claims (13)

An electric vehicle battery module frame comprising:
An upper housing having an open lower surface and an empty space in which a battery module can be mounted, and a lower plate coupled to the open lower surface of the upper housing,
The upper housing may be made of a plastic material,
The lower plate may be made of a metal material or a thermally conductive plastic material,
The lower plate is provided with protrusions at left and right ends coupled to the upper housing, respectively, and the upper housing is provided with grooves at the left and right ends into which the protrusions are inserted, respectively. According to claim 1,
The protrusion is formed on the side of the lower plate,
The ratio (L _ratio ) of the length (L _i ) of the protrusion to the total length (L _o ) of the lower plate defined by Equation 1 below is 5 to 60%,
[Equation 1]
L _ratio =L _i /L _o ×100
The electric vehicle battery module frame, characterized in that the ratio of the thickness (T _i ) of the protrusion to the thickness (T _o ) of the lower plate defined by Equation 2 below is 15 to 45%.
[Equation 2]
T _ratio =T _i /T _o ×100 According to claim 1,
The protrusion is formed on the upper surface of the lower plate,
The ratio (H _ratio ) of the height (H _i ) of the protrusion and the groove to the overall height (H _o ) of the side surface of the upper housing, defined by Equation 3 below, is 5 to 60%,
[Equation 3]
H _ratio =H _i /H _o ×100
The ratio (W _ratio ) of the width (W _i ) of the protrusion and the groove portion to the width (W _o ) of the side surface of the upper housing defined by Equation 4 below is 15 to 45%, characterized in that the electric vehicle battery module frame .
[Equation 4]
W _ratio =W _i /W _o ×100 4. The method according to any one of claims 1 to 3,
An electric vehicle battery module frame manufactured by injecting the lower plate into the injection molding machine mold and injecting the plastic material forming the upper housing into the injection molding machine mold in a molten state. 4. The method according to any one of claims 1 to 3,
One or more perforated holes are provided in the protrusion,
The electric vehicle battery module frame, characterized in that the ratio of the cross-sectional area of the entire perforated hole to the surface area of the protrusion provided with the perforated hole is 10 to 70%. 4. The method according to any one of claims 1 to 3,
The electric vehicle battery module frame, characterized in that the surface roughness (Ra) of the bonding surface of the protrusion is 6 or more, the surface roughness (Rmax) is 25S or more, and the surface roughness (Rz) is 25Z or more. 4. The method according to any one of claims 1 to 3,
An electric vehicle battery module frame, characterized in that an adhesive is applied to the bonding surface of the protrusion. 4. The method according to any one of claims 1 to 3,
The lower plate has a thermal conductivity of 0.5 to 1,000W/m·K, an electric vehicle battery module frame. 4. The method according to any one of claims 1 to 3,
The upper housing has a tensile strength of 30 to 500 MPa according to the standard ASTM D638, a flexural strength of 50 to 500 MPa according to the standard ASTM D790, and a burning time according to the standard UL-94 V test of 60 seconds or less, and the standard ASTM The thermal deformation temperature according to D648 is 50 to 300 ° C, the Izod impact strength at -30 ° C according to the standard ASTM D256 is 1 kJ / m 2 or more, and the shrinkage according to the standard ASTM D955 is 0.03 to 3% Characterized in the electric vehicle battery module frame. 10. The method of claim 9,
The plastic material forming the upper housing is selected from the group consisting of polyamide (PA), modified polyphenylene oxide (mPPO), polybutyl terephthalate (PBT), polyethyl terephthalate (PET) and polycarbonate (PC). An electric vehicle battery module frame comprising one or more selected engineering plastics and one or more reinforcing additives selected from the group consisting of glass fibers, carbon fibers, aramid fibers, carbon nanotubes and graphene. 11. The method of claim 10,
The content of the reinforcing additive is 5 to 150 parts by weight based on 100 parts by weight of the engineering plastic, characterized in that the electric vehicle battery module frame. 4. The method according to any one of claims 1 to 3,
An electric vehicle battery module frame, characterized in that a cooling plate having a refrigerant flow path through which the refrigerant flows is disposed under the lower plate. 13. The method of claim 12,
The electric vehicle battery module frame, characterized in that the ratio of the plane cross-sectional area of the refrigerant passage to the total planar cross-sectional area measured in the cross-section in which the plane cross-sectional area of the refrigerant passage is maximized among the cross-sections of the cooling plate is 50% or more.

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