PRA with Variable Cross-Sectional Area Bus Bar Structure

Abstract

The PRA (1) having a variable cross-sectional area bus bar structure of the present invention includes a battery bus bar + (5a) installed in a main body (2) covered by a main cover (3) having a vent hole (3a), a bimetal (30) that is deformed by heat inside the PRA with different thermal expansion rates, a moving bus bar (20) that expands the heat dissipation cross-sectional area of ​​the battery bus bar + (5a) from an overlapping heat dissipation section (A) to an exposed heat dissipation section (a) when moving due to the deformation of the bimetal (30), and a pad (40) that transfers heat between the bus bar + (5a, 20) with thermal grease, thereby enabling improved natural convection cooling efficiency through the vent hole (3a) by the distance traveled by the moving bus bar (20).

Description

Technology Field

[0001] The present invention relates to a bus bar of a PRA, and more specifically, to a PRA having a variable cross-sectional area bus bar structure in which the natural convection cooling efficiency of the vent hole is improved by changing the cross-sectional area of ​​the bus bar in response to heat actively generated as the internal temperature rises. Background Technology

[0002] Generally, a high-voltage battery system (BSA; Battery System Assembly) includes a battery module in which the cell voltage and cell temperature of stacked energy storage / supply battery cells are controlled, a Battery Management System (BMS) for battery control and fault diagnosis, and a Power Relay Assembly (PRA), which is a power relay assembly located between the battery module and the high-voltage connector connected to the inverter.

[0003] In particular, the above-mentioned high-voltage battery system is equipped with a cooling component for cooling water circulation, and the cooling component is mounted as a separate part to perform optimal temperature control for the battery module. Prior art literature

[0004] Korean Patent Publication KR 10-2016-0086418 A (2016.07.19) The problem to be solved

[0005] However, while the battery module inside the BSA is cooled by water cooling, in the case of the PRA, the busbar near the main relay, which is the part with the most heat, is cooled by relying only on natural convection without any special cooling device.

[0006] For example, in the Power Relay Assembly (PRA) mentioned above, the interior of the main body combined with the main cover includes a total of two relays arranged one for each polarity (+ / -) and busbars connected to both sides of the relays by bolt fastening to the high-voltage battery and the vehicle-side inverter, and when the relay is turned ON by signal control from the Battery Management System (BMS), the battery side and the inverter side are electrically connected to each other so that vehicle driving or battery charging takes place, and when the relay is turned OFF, the electrical connection between the battery side and the inverter side is cut off.

[0007] In particular, the natural convection-dependent cooling method of the above PRA utilizes the vent hole on the upper side of the main cover, so if the temperature inside the PRA rises above the standard value and overheats due to operating conditions or the assembly state of internal parts, there is a high possibility of problems such as damage to the main relay inside the main body and fire.

[0008] Consequently, the natural convection-dependent cooling method of the above PRA poses a risk of relay operation issues due to the continuous rise in the internal temperature of the PRA. Furthermore, since heat control relies on the surface area of ​​the busbar connected to the top of the relay, securing the necessary surface area is crucial; this results in a cost disadvantage due to excessive material costs for the busbar.

[0009] Accordingly, the present invention, taking into account the above points, aims to provide a PRA having a variable cross-sectional area bus bar structure in which the cross-sectional area of ​​the bus bar is deformed by bimetal deformation caused by the internal temperature rise of the PRA, thereby increasing the heat dissipation surface area exposed toward the vent hole by the distance traveled by the bus bar, so that the natural convection cooling efficiency is improved, and the main relay burnout and fire occurrence are prevented in advance by preventing overheating through improved cooling efficiency even when the internal temperature of the PRA rises. means of solving the problem

[0010] A PRA having a variable cross-sectional area bus bar structure according to the present invention for achieving the above-mentioned purpose comprises a bus bar that forms a current path in a main body covering the interior with a main cover having vent holes and dissipates internal heat of the PRA according to relay operation, a movable bus bar that forms an overlapping heat dissipation section on the bus bar, and a bimetal connected to the movable bus bar, wherein the movable bus bar forms an exposed heat dissipation section by moving the overlapping heat dissipation section caused by the bimetal deformed by the internal heat of the PRA, and the overlapping heat dissipation section and the exposed heat dissipation section expand the heat dissipation cross-sectional area of ​​the bus bar.

[0011] Preferably, the overlapping heat dissipation section is formed as a double structure in which the movable bus bar is superimposed on the upper part of the bus bar.

[0012] Preferably, the movable bus bar includes a guide member for moving the overlapping heat dissipation section, and the guide member is composed of a moving slot for sliding movement of the movable bus bar and a guide pin fitted into the moving slot and fixed to the bus bar, and the guide member is positioned on both the left and right sides of the movable bus bar as a pair of first and second guide members.

[0013] Preferably, the bimetal is a composite of dissimilar metal materials with different thermal expansion rates and includes a bimetal fixing member that is bolted to the main cover or insert-molded, and a bimetal connecting member that is welded or press-welded to the movable bus bar.

[0014] Preferably, a pad is provided between the bus bar and the movable bus bar to smoothly transfer heat conducted from the bus bar to the movable bus bar, and thermal grease is applied to the pad.

[0015] In addition, the PRA having a variable cross-sectional area bus bar structure of the present invention for achieving the above-mentioned purpose comprises a battery bus bar + and a battery bus bar - forming a battery terminal block in a main body covered by a main cover having vent holes, and an inverter bus bar + and an inverter bus bar forming an inverter terminal block; a bimetal formed by a bond of dissimilar metal materials with different thermal expansion rates and deformed by internal heat of the PRA due to current conduction and relay operation; a movable bus bar that expands the heat dissipation cross-sectional area of ​​the battery bus bar + into an exposed heat dissipation section extended from an overlapping heat dissipation section formed with the battery bus bar + when the bimetal moves due to deformation; and a pad located between the battery bus bar + and the movable bus bar, wherein the pad is characterized by applying thermal grease to smoothly transfer heat conducted from the battery bus bar + to the movable bus bar.

[0016] Preferably, the overlapping heat dissipation section is formed as a double structure in which the moving bus bar is superimposed on the upper part of the battery bus bar+.

[0017] Preferably, on both the left and right sides of the moving bus bar, a pair of first and second guide members are included to guide the movement of the overlapping heat dissipation section, and each of the first and second guide members is composed of a moving slot for sliding movement of the moving bus bar and a guide pin fitted into the moving slot and fixed to the battery bus bar+.

[0018] Preferably, the bimetal comprises a pair of first and second bimetal fixing members that are bolted to the main cover or insert-molded, and a bimetal connecting member that is welded or press-welded to the movable bus bar. Effects of the invention

[0019] The PRA of the present invention has a temperature-responsive variable cross-sectional area bus bar structure that combines a double-structure bus bar and a bimetal, thereby effectively discharging heat to the outside of the PRA through vent holes when heat is generated inside the PRA due to power supply, thus realizing the following operations and effects.

[0020] First, the surface area of ​​the bus bar on the upper side of the relay can be variably adjusted according to the internal temperature of the PRA, allowing for effective control of the internal temperature of the PRA during current flow compared to conventional PRAs that rely solely on natural convection.

[0021] Second, in the case of PRAs applied to high-specification BSAs, the problem of having to secure excessive thickness and area for the bus bar on the upper side of the relay can be resolved by using a variable cross-sectional area bus bar structure, which is cost-effective as it allows for a reduction in thickness and area. Brief explanation of the drawing

[0022] FIG. 1 is a configuration diagram of a PRA having a variable cross-sectional area bus bar structure according to the present invention, FIG. 2 is a diagram of the variable cross-sectional area bus bar structure of the PRA according to the present invention, and FIG. 3 is an operation mechanism of the bus bar variable cross-sectional area structure when the internal temperature of the PRA rises according to the present invention. Specific details for implementing the invention

[0023] Embodiments of the present invention will be described in detail below with reference to the attached illustrative drawings. Since these embodiments are merely examples and can be implemented in various different forms by those skilled in the art to which the present invention pertains, the embodiments described herein are not limited to the examples described herein.

[0024] Referring to FIG. 1, a Power Relay Assembly (PRA) (1), which is a Power Relay Assembly, applies a bus bar cooling unit (10) to the main body of the Power Relay, which is an internal electrical circuit component of the main body (2) covered by a main cover (3). The bus bar cooling unit (10) enables the expansion of the heat dissipation area of ​​the bus bar (4) by heat generated actively according to the ambient temperature inside the PRA, thereby maintaining the temperature inside the PRA at a constant level through the vent hole (3a) to prevent overheating, thereby preventing damage to the main relay and fire in advance. In this case, the PRA (1) is applied to a high-voltage battery system (BSA; Battery System Assembly), and is particularly applied to a high-specification BSA.

[0025] For example, the main body (2) provides a main relay and bus bar connection point, and the main cover (3) forms a plurality of vent holes (3a) while protecting the components inside the PRA from external factors so that the heat inside the PRA can be released to the outside through natural convection cooling of air.

[0026] For example, the bus bar (4) is connected to the main relay and bolt (9) using the internal structure of the main body (2), and when energized, it transmits current along a predetermined path and also performs the role of discharging heat generated from the main relay.

[0027] For example, the above bus bar cooling unit (10) includes a bus bar (4), a movable bus bar (20), and a bimetal (30), the bus bar (4) is either a battery or an inverter-side bus bar (see FIG. 2), the movable bus bar (20) is in close contact with the upper surface of the bus bar (4), and the bimetal (30) is bent in shape according to the heat rise inside the PRA with different thermal expansion rates to pull the movable bus bar (20).

[0028] In particular, the above bus bar (4) and the above movable bus bar (20) form a bus bar dual structure in which the bus bar (4) is the lower bus bar and the movable bus bar (20) is the upper bus bar, thereby having a bus bar variable cross-sectional area structure in which the upper bus bar above the main relay among the dual structures of the upper bus bar and the lower bus bar expands as the bus bar temperature rises.

[0029] And the above-mentioned moving bus bar (20) is in close contact with the upper surface of the bus bar (4) to form an overlapping section, and the overlapping section of the bus bar (4) is exposed by sliding movement (e.g., in the x-axis direction of the xyz coordinates) according to the shape deformation of the bimetal (30).

[0030] To this end, the above-mentioned moving bus bar (20) is provided with a guide member (23) consisting of a pair of first and second guide members (23a, 23b) for sliding movement, and each of the first and second guide members (23a, 23b) is composed of a moving slot (24) that is drilled on both the left and right sides (e.g., in the y-axis direction of the xyz coordinates) and a guide pin (25) that is fixed to the bus bar (4) and inserted into the moving slot (24) to stabilize the sliding movement.

[0031] Additionally, the bimetal (30) is a composite of heterogeneous metal materials with different thermal expansion rates, and its shape is bent due to the ambient temperature caused by the rise in internal heat of the PRA, so that the heat dissipation area of ​​the lower bus bar (4) is expanded by moving the movable bus bar (20), which is the upper bus bar of the double-structure bus bar, due to the different thermal expansion rates.

[0032] Referring to FIG. 2, an example is shown in which the bus bar cooling unit (10) is applied to one of the bus bars (4).

[0033] As described above, the bus bar (4), which is fastened with bolts (9) on both sides of the main relay on the inner side of the main body (2), is divided into battery bus bar + (5a) and battery bus bar - (5b), which are battery terminal blocks, and inverter bus bar + (6a) and inverter bus bar - (6b), which are inverter terminal blocks, so that there are a total of two, one for each polarity (+) and (-).

[0034] For example, the above battery bus bar + / -(5a, 5b) is connected to the high-voltage battery and the above inverter bus bar + / -(6a, 6b) is connected to the vehicle-side inverter, and when the relay is turned ON according to the signal from the BMS side, the battery side and the inverter side are electrically connected to each other so that vehicle driving or battery charging is performed, whereas when the relay is turned OFF, the electrical connection is cut off.

[0035] In this configuration, the bus bar cooling unit (10) is exemplified as being applied to the battery bus bar + (5a), but this is only one example and may be installed on any one of the bus bars, the battery bus bar + (5a), the battery bus bar - (5b), the inverter bus bar + (6a), and the inverter bus bar - (6b), or on each of the bus bars.

[0036] For example, the above bus bar cooling unit (10) forms a dual structure in which the battery bus bar + (5a) is the lower bus bar and the upper bus bar, the movable bus bar (20), changes the cross-sectional area of ​​the battery bus bar + (5a) side to a variable cross-sectional area, and the bimetal (30), which is a bimetal (30) made of different metal materials with different thermal expansion rates, pulls the movable bus bar (20) through a shape that bends due to the heat rise inside the PRA.

[0037] Therefore, the sliding movement of the movable bus bar (20) relative to the battery bus bar + (5a) is stabilized by the guide pin (25) of the first and second guide members (23a, 23b) being inserted into the movable slot (24) and fixed to the upper surface of the battery bus bar + (5a).

[0038] And the bimetal (30) is equipped with a bimetal fixing member (31) that is fixed to the inside of the main cover (3) and a bimetal connecting member (33) that is connected to the side of the movable bus bar (20). The bimetal fixing member (31) is composed of a pair of first and second bimetal fixing members (31a, 31b) located on both the left and right sides (e.g., in the y-axis direction of the xyz coordinates) so that the lower part is pulled by the deformation of the middle part while the upper part of the bimetal is fixed, and the bimetal connecting member (33) causes the movable bus bar (20) to be pulled by the deformation of the bimetal (30).

[0039] To this end, the bimetal (30) is made of a folded plate having an upper horizontal section and a lower vertical section with an L-shaped cross section, and first and second bimetal fixing members (31a, 31b) are applied to the upper horizontal section of the L-shaped cross section, and a bimetal connecting member (33) is applied to the lower vertical section of the L-shaped cross section.

[0040] For example, each of the first and second bimetal fixing members (31a, 31b) is bolted to the main cover (3) by screws or bolts, or molded to the main cover (3) by insert injection. The bimetal connecting member (33) connects the contact surface between the lower part of the bimetal (30) and the side of the movable bus bar (20) by welding or pressure welding.

[0041] Additionally, the bus bar cooling unit (10) includes a pad (40) interposed between the battery bus bar + (5a) and the movable bus bar (20) to smoothly transfer heat conducted through the main relay and the lower bus bar, the battery bus bar + (5a), to the upper bus bar, the movable bus bar (20), and the pad (40) is coated with thermal grease.

[0042] Meanwhile, FIG. 3 illustrates the operating state in which the bus bar cooling unit (10) responds to the rise in internal temperature of the PRA within the internal space of the main body / cover (2, 3) as a cross-sectional state before bus bar expansion (A), bus bar expansion (B), and after bus bar expansion (C). In this case, the cooling action is described in relation to the rise in internal temperature of the PRA, regardless of the operation of the normal electrical circuit components due to bus bar energization.

[0043] For example, in the state before the bus bar expansion (A), there is no rise in the internal temperature of the PRA, so the bimetal (30) also maintains the initial state of the “L” cross-section of the bent plate without thermal expansion.

[0044] Therefore, the movable bus bar (20), which forms a double structure with the battery bus bar +(5a), forms an overlapping heat dissipation section (A) with a width equal to the width of the upper surface of the battery bus bar +(5a).

[0045] Next, in the state of the bus bar extension (B), the heat from the main relay and battery bus bar + (5a) is transferred to the moving bus bar (20) through the pad (40), causing an increase in the internal temperature of the PRA, which causes the bimetal (30) to bend due to deformation caused by thermal expansion, and the deformation of the bimetal (30) pulls the moving bus bar (20), in which the lower vertical section is connected by the bimetal connecting member (33), while the upper horizontal section is fixed to the main cover (3) by the first and second bimetal fixing members (31a, 31b).

[0046] As a result, the above-mentioned moving bus bar (20) moves the overlapping heat dissipation section (A) through sliding movement that is pulled in the bending direction of the bimetal (30), thereby forming an exposed heat dissipation section (a) on the battery bus bar + (5a), and thus the heat dissipation cross-sectional area of ​​the bus bar (4) is expanded to the sum of the overlapping heat dissipation section (A) and the exposed heat dissipation section (a).

[0047] Then, as in the cross-sectional state (C) after the bus bar expansion, the bus bar cooling section (10) promotes an internal heat dissipation effect (i.e., natural convection cooling) by increasing the heat dissipation surface area in the exposed section (a) of the battery bus bar + (5a) facing the vent hole (3a) of the main cover (3), and this internal heat dissipation continues until the bimetal (30) and the movable bus bar (20) return to the initial state (i.e., before the bus bar expansion (A)), thereby lowering the internal temperature of the PRA.

[0048] Accordingly, the above PRA (1) is formed with a bus bar cooling unit (10) that can actively release heat generated according to the atmosphere temperature inside the PRA to the outside of the PRA, thereby maintaining the internal temperature at a constant level, and through this, the overheating phenomenon is prevented, so that the main relay burnout and fire can be prevented in advance.

[0049] As described above, the PRA (1) having a variable cross-sectional area bus bar structure according to the present embodiment includes a battery bus bar + (5a) installed in a main body (2) covered by a main cover (3) having a vent hole (3a), a bimetal (30) that is deformed by the heat inside the PRA with different thermal expansion rates, a moving bus bar (20) that expands the heat dissipation cross-sectional area of ​​the battery bus bar + (5a) from an overlapping heat dissipation section (A) to an exposed heat dissipation section (a) when the bimetal (30) is deformed and moved, and a pad (40) that transfers heat between the bus bar + (5a, 20) with thermal grease, thereby enabling improved natural convection cooling efficiency through the vent hole (3a) by the distance traveled by the moving bus bar (20). Explanation of the symbols

[0050] 1 : PRA(Power Relay Assembly) 2 : Main Body 3 : Main Cover 3a: Vent hole 4 : Bus Bar 5a : Battery bus bar + 5b : Battery bus bar - 6a : Inverter bus bar + 6b : Inverter bus bar - 9 : Bolt 10: Bus bar cooling unit 20: Moving bus bar 21 : Moving plate 23: Absence of guide 23a, 23b: 1st and 2nd guide members 24: Move slot 25: Guide pin 30 : Bimetal 31: Bimetal fixing member 31a, 31b: 1st and 2nd bimetal fixing members 33: Bimetal connecting member 40 : Pad

Claims

Claim 1 A PRA (Power Relay Assembly) having a variable cross-sectional area bus bar structure, wherein the PRA covers the interior of a main body with a main cover having a vent hole, the PRA includes a bus bar that forms a current path in the main body and dissipates internal heat of the PRA according to relay operation, a movable bus bar that forms an overlapping heat dissipation section on the bus bar, and a bimetal connected to the movable bus bar, wherein the movable bus bar forms an exposed heat dissipation section by moving the overlapping heat dissipation section caused by the bimetal deformed by the internal heat of the PRA, and the overlapping heat dissipation section and the exposed heat dissipation section expand the heat dissipation cross-sectional area of ​​the bus bar. Claim 2 A PRA having a variable cross-sectional area bus bar structure, wherein, in claim 1, the overlapping heat dissipation section is formed as a double structure in which the movable bus bar is superimposed on the upper part of the bus bar. Claim 3 A PRA having a variable cross-sectional area bus bar structure according to claim 1, wherein the movable bus bar includes a guide member for moving the overlapping heat dissipation section, and the guide member comprises a movable slot for sliding movement of the movable bus bar and a guide pin fitted into the movable slot and fixed to the bus bar. Claim 4 A PRA having a variable cross-sectional area bus bar structure according to claim 3, wherein the guide member is a pair of first and second guide members positioned on both the left and right sides of the movable bus bar. Claim 5 A PRA having a variable cross-sectional area bus bar structure, wherein, in claim 1, the bimetal is a composite of heterogeneous metal materials with different thermal expansion coefficients. Claim 6 A PRA having a variable cross-sectional area bus bar structure according to claim 5, wherein the bimetal comprises a bimetal fixing member that is bolted to the main cover or insert-molded, and a bimetal connecting member that is welded or press-welded to the movable bus bar. Claim 7 A PRA having a variable cross-sectional area bus bar structure, characterized in that, in claim 1, a pad is provided between the bus bar and the movable bus bar to smoothly transfer heat conducted from the bus bar to the movable bus bar, and the pad is thermal grease. Claim 8 A Power Relay Assembly (PRA) comprising a battery bus bar + and a battery bus bar - forming a battery terminal block, and an inverter bus bar + and an inverter bus bar - forming an inverter terminal block, in a main body covered by a main cover having a vent hole, wherein the PRA comprises: a bimetal formed by a bond of dissimilar metal materials with different thermal expansion rates and deformed by internal heat of the PRA due to current conduction and relay operation; a movable bus bar that expands the heat dissipation cross-sectional area of ​​the battery bus bar + into an exposed heat dissipation section extended from an overlapping heat dissipation section formed with the battery bus bar + upon movement due to the deformation of the bimetal; and a pad located between the battery bus bar + and the movable bus bar, wherein the pad is coated with thermal grease to smoothly transfer heat conducted from the battery bus bar + to the movable bus bar. Claim 9 A PRA having a variable cross-sectional area bus bar structure, wherein, in claim 8, the overlapping heat dissipation section is formed as a double structure in which the movable bus bar is superimposed on the upper part of the battery bus bar +. Claim 10 A PRA having a variable cross-sectional area bus bar structure according to claim 8, wherein a pair of first and second guide members for guiding the movement of the overlapping heat dissipation section are included on both the left and right sides of the movable bus bar, and each of the first and second guide members is composed of a movable slot for sliding movement of the movable bus bar and a guide pin fitted into the movable slot and fixed to the battery bus bar+. Claim 11 A PRA having a variable cross-sectional area bus bar structure according to claim 8, wherein the bimetal is a pair of first and second bimetal fixing members, and the first and second bimetal fixing members each include a bimetal connecting member that is bolted to the main cover by a screw or bolt, or molded to the main cover by insert injection, and welded or press-welded to the movable bus bar.

Images