Vehicle power unit protection structure

Abstract

The power unit protection structure (1) of the vehicle (V) includes: a side beam (3) of the vehicle (V); a power unit (2) mounted on the vehicle (V) having a protected component (25) arranged opposite to the side beam (3) in the vehicle width direction; and a fluid hose (4) connected to the radiator (5) of the vehicle (V). At least a portion (45) of the fluid hose (4) is disposed between the side beam (3) and the protected component (25), overlapping both the side beam (3) and the protected component (25) when viewed from the side of the vehicle (V).

Description

Technical Field

[0001] This invention relates to a protection structure for the power unit of a vehicle. Background Technology

[0002] Patent document 1 discloses a front side beam structure for a vehicle. In this front side beam structure, during a frontal collision, the high-strength front side beam, composed of tubular hollow components, can bend not only at the first vulnerable part but also at the second vulnerable part, thereby increasing the impact absorption stroke and improving the collision energy absorption effect.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: (Japanese) Patent No. 5749748 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, in the technology described in Patent Document 1, although the front side beam bends during a collision to absorb the energy of the impact, the bent front side beam can interfere with the power unit. Furthermore, even in vehicles with front side beams other than those described in Patent Document 1, the front side beam sometimes bends during a collision and interferes with the power unit. If the bent front side beam interferes with the power unit, components located in the power unit may be damaged. Adding a protector to protect components located in the power unit increases weight and cost.

[0008] The purpose of this invention is to provide a power unit protection structure for a vehicle that can reduce or prevent damage to the protected components of the power unit during a vehicle collision without adding other components.

[0009] Technical solutions for solving technical problems

[0010] According to one aspect of the present invention, a power unit protection structure for a vehicle includes: a side beam of the vehicle; a power unit mounted on the vehicle, having a protected component arranged opposite to the side beam in the width direction of the vehicle; and a fluid hose connected to the radiator of the vehicle, at least a portion of the fluid hose being disposed between the side beam and the protected component, and overlapping both the side beam and the protected component when viewed from the side of the vehicle.

[0011] Invention Effects

[0012] Based on the above structure, without adding other components, it is possible to reduce or prevent damage to the protected components of the power unit during a vehicle collision. Attached Figure Description

[0013] Figure 1 This is a top view of the front of a vehicle equipped with the power unit protection structure of the vehicle according to an embodiment of the present invention.

[0014] Figure 2 yes Figure 1 This is a partial cross-sectional view of the vehicle's power unit protection structure, viewed from the front of the vehicle.

[0015] Figure 3 yes Figure 2 Enlarged view of the main parts.

[0016] Figure 4 It is a partial cross-sectional perspective view of the busbar connection and the area around the opening of the power unit, viewed from the right front of the vehicle.

[0017] Figure 5 It is a three-dimensional cross-sectional view of the perimeter of the fixing part of the front beam to which the liquid hose is fixed, viewed from the left front of the vehicle.

[0018] Figure 6 Viewed from the right side of the vehicle Figure 1 A side view of the vehicle's power unit protection structure.

[0019] Figure 7 This is a diagram used to illustrate the shock absorption characteristics of liquid hoses.

[0020] Figure 8 It means Figure 1 The top view of the right half of the front of the vehicle is a diagram showing its state before deformation.

[0021] Figure 9 It means Figure 1 The top view of the right half of the front of the vehicle is a diagram showing the deformation state of the vehicle during a collision. Detailed Implementation

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, FR represents the front of the vehicle V, RR represents the rear, RH represents the right, LH represents the left, UP represents the top, and DN represents the bottom. Unless otherwise specified, the terms front, rear, right, left, top, and bottom in the following description refer to the directions of the vehicle V. The vehicle width direction refers to the left-right direction of the vehicle V.

[0023] [Implementation Method]

[0024] Reference Figures 1-9 The power unit protection structure 1 of the vehicle according to an embodiment of the present invention (hereinafter referred to as power unit protection structure 1) will be described. Figure 1As shown, the power unit protection structure 1 is disposed at the front VF of the vehicle V, and includes a power unit 2, a front side beam (side beam) 3 of the vehicle V, and a fluid hose (radiator hose) 4. The power unit 2 has a manifold cover (protected component) 25, described later, as a protected component that should be protected from damage during a collision with the vehicle V. The fluid hose 4 is sandwiched between the power unit 2 and the front side beam 3 during a collision with the vehicle V, mitigating or preventing damage to the manifold cover 25. In this embodiment, the fluid hose 4 includes both the hose and the fluid contained within it.

[0025] like Figure 1 As shown, vehicle V includes a power unit 2, a front side beam 3, fluid hoses 4, a radiator 5, and a battery 6. Vehicle V has a drive compartment DR at its front part VF. A passenger compartment is located behind the drive compartment DR, and a floor panel (not shown) is located at the bottom of the passenger compartment.

[0026] like Figure 1 As shown, the power unit 2 is mounted in the drive compartment DR of vehicle V and fixed to a structural component (not shown) of vehicle V. Figure 2 , Figure 3 As shown, the power unit 2 includes a housing 21, a motor 22, and an inverter (power conversion device) 23. The motor 22 is a drive source that provides driving force to the wheels of the vehicle V, and is, for example, a three-phase AC synchronous motor. The motor 22 has a motor-side busbar (bus) 22a for receiving power from the inverter 23. The inverter 23 converts the DC current supplied from the high-voltage battery 6 (described later) via a junction box into three-phase AC current using power semiconductors and supplies it to the motor 22. The inverter 23 has an inverter-side busbar 23a for supplying the converted three-phase AC power to the motor 22. Figures 2-4 As shown, the motor-side busbar 22a and the inverter-side busbar 23a are electrically connected and fixed to each other at the busbar connection part (connection part) 24 by busbar fixing bolts 24b. The housing 21 is made of metal and houses the motor 22, the inverter 23, the motor-side busbar 22a, and the inverter-side busbar 23a.

[0027] like Figures 2-4 As shown, the busbar connector 24 is disposed within the housing 21 on the right side of the vehicle V. Figure 4As shown, a roughly rectangular opening 24a, which opens to the right and has rounded corners when viewed from above, is formed on the side wall 21a of the housing 21 where the busbar connection 24 is located. The opening 24a is used to connect and secure the motor-side busbar 22a and the inverter-side busbar 23a together using the busbar fixing bolts 24b, and allows access to the busbar connection 24 via tools. When the opening 24a is not covered by the busbar cover 25, the busbar connection 24 is exposed to the outside of the housing 21 through the opening 24a. Furthermore, the opening 24a can also be used to disconnect and secure the motor-side busbar 22a and the inverter-side busbar 23a, or it can be used solely for disconnection and securing.

[0028] With the busbar connection portion 24 exposed, there is a possibility that water may seep into the housing 21 through the opening 24a, or that a user may come into contact with the busbar connection portion 24 (motor-side busbar 22a, inverter-side busbar 23a, busbar fixing bolt 24b) using their fingers. To prevent this, after the motor-side busbar 22a and inverter-side busbar 23a are fixed, the opening 24a is blocked by the busbar cover 25, which is a protected component. More specifically, as... Figure 6 As shown, the roughly rectangular busbar cover 25, made of metal and with rounded corners when viewed from above, is fixed to the side wall 21a by cover fixing bolts 25a in a manner that blocks the opening 24a. With the busbar cover 25 fixed to the side wall 21a, the opening 24a is completely covered by the busbar cover 25, preventing water from seeping into the housing 21 through the opening 24a and preventing the user from contacting the busbar connection parts 24 (motor-side busbar 22a, inverter-side busbar 23a, busbar fixing bolts 24b) with their fingers, etc. Since the busbar cover 25 is separate from the housing 21 of the power unit 2, the strength of at least a portion (e.g., the end) of the busbar cover 25 mounted on the housing 21 may be lower than the strength of the housing 21. Alternatively, the motor-side busbar 22a and the inverter-side busbar 23a can be fixed beforehand without using the opening 24a. In this case, the opening 24a is used when disconnecting and fixing the motor-side busbar 22a and the inverter-side busbar 23a.

[0029] like Figure 1 As shown, the front side beam 3 is a structural component of the vehicle V made of steel plates or the like. In this embodiment, it is a front side beam located on the right side of the front part VF in front of the vehicle V. The front side beam 3 is located to the right of the drive compartment DR and is configured opposite to at least a portion of the housing 21 in the vehicle width direction. More specifically, as... Figure 2 , Figure 3 , Figure 5As shown, the front side beam 3 is formed in a square tube shape and extends in the front-rear direction, having an inner side surface 31 that faces the side wall 21a of the housing 21 in the vehicle width direction. The inner side surface 31 is arranged to face the manifold cover 25 in the vehicle width direction. The inner side surface 31 has a fixing part 32 for fixing the liquid hose 4.

[0030] Battery 6 is a high-voltage drive battery that supplies power to power unit 2 and is electrically connected to inverter 23. For example... Figure 1 As shown, the battery 6 is located on the lower side of the floor panel below the front side beam 3. A cooling unit (not shown) connected to a liquid hose 4 is provided on the battery 6 to cool it.

[0031] Radiator 5 supplies cooling water to the cooling unit of battery 6 for cooling battery 6. For example... Figure 1 As shown, the radiator 5 includes a main body 51 located in front of the drive compartment DR of the vehicle V and a coolant reservoir 52. Figure 6 As shown, the main body 51 has an outlet (connection port) 51a located above the front side beam 3. The main body 51 is equipped with a cooling mechanism (not shown) for cooling water, and the cooling water obtained by the cooling mechanism is supplied to the liquid hose 4 through the outlet 51a. Cooling water returning from the cooling unit flows into the main body 51 through the liquid hose (not shown) connected to the cooling unit of the main body 51 and the battery 6.

[0032] like Figure 1 As shown, the liquid hose 4 forms a water passage (flow path) between the radiator 5 and the cooling unit of the battery 6, supplying cooling water to the cooling unit. Figure 3 , Figure 5 As shown, the liquid hose 4 is composed of a composite material consisting of a cylindrical outer cylinder 4a made of rubber and a liquid (cooling water) 4b present inside the outer cylinder 4a. Figure 1 , Figure 6 As shown, the liquid hose 4 is connected to the outlet 51a of the main body 51 of the radiator 5 via the first connecting part 41, and to the cooling unit of the battery 6 via the second connecting part 42. Additionally, the liquid hose 4 is connected to other liquid hoses H via the third connecting part 43, and is connected to the reservoir 52 via these other liquid hoses H. Figure 1 , Figure 3 , Figure 5 As shown, the outer tube 4a of the liquid hose 4 is fixed to the fixing part 32 of the front beam 3 by a clamp 44 formed of resin. Figure 1 , Figure 5 , Figure 6 , Figure 8As shown, the overlapping portion 45, which is at least a part of the liquid hose 4, is disposed between the inner side surface 31 of the front side beam 3 and the manifold cover 25, and overlaps with both the inner side surface 31 of the front side beam 3 and the manifold cover 25 when viewed from the side of the vehicle V.

[0033] Figure 7 This is a graph illustrating the impact absorption characteristics of the liquid hose 4. The horizontal axis represents the crushing amount, and the vertical axis represents the reaction force. Additionally, in Figure 7 In the diagram, line L1 (solid line) represents the relationship between the crushing amount and the reaction force when an impact is applied to the liquid hose 4, and line L2 (dashed line) represents the relationship between the crushing amount and the reaction force when an impact is applied to a solid, single-material component in which the liquid 4b of the liquid hose 4 is replaced with the same material as the outer cylinder 4a (rubber in this embodiment). Figure 7 As shown, in the case of a single material, the reaction force relative to the crushing amount continuously increases as shown by line L2, and the energy absorption becomes the area EA2 of the second region enclosed by the horizontal axis, the vertical axis, and line L2. On the other hand, as... Figure 7 As shown, when a liquid hose 4 made of composite material is installed inside the outer cylinder 4a, containing liquid 4b, since it is not a single material, the reaction force relative to the crushing amount increases stepwise as shown by line L1, and the energy absorption becomes the area EA1 of the first region enclosed by the horizontal axis, the vertical axis, and line L1. In the case of the liquid hose 4, by increasing the reaction force stepwise in this way, the energy absorption can be increased. Figure 7 The crushing amount up to the upper limit of the reaction force (in this embodiment, the reaction force of damage to the busbar shroud 25) FMX, indicated by the dotted line, is greater than that of a single material in terms of the energy that can be absorbed (the area of ​​the first region EA1 > the area of ​​the second region EA2).

[0034] Next, the power unit protection structure 1 during a vehicle V collision will be explained. Figure 8 This indicates the state of the front VF of vehicle V before the collision. Figure 9 This indicates the deformation state of the front part VF of vehicle V during a frontal collision. Figure 8 , Figure 9 In Chinese, only means Figure 1 The right half of the vehicle. Additionally... Figure 3 The dotted lines represent the deformation of the front side beam 3 and the fluid hose 4 during a frontal collision with vehicle V. It should be noted that the collision is not limited to a frontal collision; any deformation of the front side beam 3 towards the power unit 2, resulting in interference with the manifold cover 25, is acceptable. Figure 9As shown, during a frontal collision with vehicle V, the front side beam 3 bends and deforms to the left of vehicle V (towards the power unit 2), trapping the liquid hose 4 between the deformed front side beam 3 and the power unit 2. As the front side beam 3 deforms, the liquid hose 4 moves together with it towards the power unit 2. More specifically, the liquid hose 4 deforms at the overlapping portion 45 between the front side beam 3 and the manifold 25 fixed to the side wall 21a of the housing 21 and / or its adjacent portion, where the liquid hose 4 is trapped. Thus, the liquid hose 4... Figure 8 The state before deformation shown Figure 9 Until the deformation state shown, as Figure 7 As shown by line L1, the impact force exerted on the manifold cover 25 by the front beam 3 is absorbed in a stepped manner, reducing or preventing damage to the manifold cover 25. In addition, when the liquid hose 4 deforms, the liquid 4b in the outer cylinder 4a moves towards the storage tank 52, and the liquid 4b will not be blown out.

[0035] The effects of this embodiment will be explained below.

[0036] At least a portion (overlapping portion 45) of the liquid hose 4 is disposed between the front side beam 3 (inner side 31) and the manifold cover 25, which are opposite each other in the vehicle width direction, and overlaps with both the front side beam 3 and the manifold cover 25 when viewed from the side of the vehicle V. Therefore, in the event of a collision with the vehicle V, the liquid hose 4 deforms between the front side beam 3 and the manifold cover 25, absorbing the impact force. Thus, direct interference between the bent front side beam 3 and the manifold cover 25, which is a protected component of the power unit 2, can be prevented, and damage to the manifold cover 25 can be mitigated or prevented. By preventing or minimizing damage to the manifold cover 25, the formation of a gap between the manifold cover 25 and the opening 24a of the power unit 2 can be suppressed, preventing water from entering the power unit 2 and preventing the user from inserting their fingers into the gap.

[0037] As a shock absorption component, the liquid hose 4 provided by the vehicle V for cooling the battery 6 is utilized. Therefore, as a shock absorption component, no other components such as protectors are required, which can suppress the increase in weight and cost.

[0038] The liquid hose 4 is made of a composite material consisting of an outer cylinder 4a and a liquid 4b. Therefore, when subjected to impact, the reaction force of the liquid hose 4 increases in a stepwise manner, and its impact energy absorption is greater than that of impact-absorbing components made of a single material. Thus, by utilizing the liquid hose 4 with its large impact energy absorption capacity, damage to the manifold 25 can be effectively reduced or prevented.

[0039] The fluid hose 4 is fixed to the front side beam 3. Therefore, in the event of a collision with the vehicle V, the fluid hose 4 moves together with the front side beam 3 and is more reliably clamped between the front side beam 3 and the manifold cover 25. In addition, since the front side beam 3 is used to fix the fluid hose 4 between the power unit 2 and the front side beam 3, there is no need to install additional brackets or the like for fixing the fluid hose 4 to other components of the vehicle V.

[0040] The liquid hose 4 is connected to the liquid reservoir 52 of the vehicle V. Therefore, when the liquid hose 4 is sandwiched between the front side beam 3 and the manifold cover 25 during a collision of the vehicle V, it can prevent the liquid 4b from being blown out due to the pressure rise inside the liquid hose 4.

[0041] The fluid hose 4 is connected to the outlet 51a of the radiator 5 located above the front side beam 3, forming a water passage between the battery 6 and the radiator 5 located below the front side beam 3. Therefore, the middle portion of the fluid hose 4, which runs generally diagonally downwards from the front to the rear, is positioned between the front side beam 3 and the power unit 2 (manifold cover 25). Thus, for example, compared to the case where the fluid hose 4 runs from the main body 51 of the radiator 5 in the vehicle width direction, it is not necessary to bypass the fluid hose 4 to place it between the front side beam 3 and the power unit 2 (manifold cover 25), allowing for a shorter routing path. Therefore, it is not necessary to significantly change the routing path of the fluid hose 4, or significantly increase or change the length of the fluid hose 4.

[0042] Busbar cover 25 is a cover that blocks the opening 24a of the busbar connection 24 between the motor-side busbar 22a and the inverter-side busbar 23a of the power unit 2. Therefore, the busbar cover 25 is of high priority in protecting the parts and components of the power unit 2 from damage.

[0043] [Variation Example]

[0044] The embodiments of the present invention have been described above, but the following structure can also be adopted in this embodiment.

[0045] The wiring path of the liquid hose 4 is not limited to the above-described embodiment. For example, it may not be like the modified example. Figure 6 Instead of the liquid hose 4A shown by the dashed line, which runs diagonally upwards and backwards from near the clamp 44, this modified example has a liquid hose 4A arranged diagonally downwards and backwards. Therefore, the liquid hose 4A in this variation can be routed along a shorter path than the liquid hose 4 in the above embodiment.

[0046] The fluid hose 4 may not be fixed to the front side beam 3. For example, the portion of the fluid hose 4 located between the power unit 2 and the front side beam 3 may not be fixed to other components of the vehicle V. The fluid hose 4 may be fixed to the power unit 2, or it may be fixed to components of the vehicle V other than the power unit 2 and the front side beam 3.

[0047] The liquid hose 4 may not be connected to the reservoir 52. Alternatively, the liquid hose 4 may be connected to the inlet (connection port) of the main body 51 of the radiator 5 via the first connection 41, where the liquid 4b is cooling water returning from the cooling unit to the radiator 5. The liquid 4b is not limited to cooling water; it can also be a coolant. The liquid 4b can be used not only for cooling the battery 6 but also for heating.

[0048] The liquid hose 4 may not form a water passage for cooling the battery 6. For example, the liquid hose 4 may also form a water passage for cooling vehicle components other than the battery 6, such as the power unit 2.

[0049] The battery 6 can also be located in a location other than under the floor panel of the vehicle V. The battery 6 can also be located outside the position under the front side beam 3.

[0050] In the above embodiment, a motor-side busbar 22a and an inverter-side busbar 23a are used in the electrical connection between the motor 22 and the inverter 23, and the busbar cover 25 is used as the protected component, but it is not limited to this. The protected component may also be the power harness of the high-voltage system that electrically connects the motor 22 and the inverter 23, or the connector connection of the power harness of the high-voltage system to the motor 22 and the inverter 23. Alternatively, the protected component may also be the power harness of the low-voltage system that connects the motor 22 and the inverter 23, or the connector connection of the power harness of the low-voltage system to the motor 22 and the inverter 23. In these cases, the part of the motor 22 and the inverter 23 connected to the connector connection of the power harness of the high-voltage system and the power harness of the low-voltage system corresponds to the busbar connection part 24.

[0051] In the above embodiments, the front side beam 3 may have one or more weak points, or it may have no weak points. When the front side beam 3 has weak points, it is easy to imagine how the front side beam 3 will deform during a vehicle V collision, and the position of the fixing part 32 of the front side beam 3 that fixes the fluid hose 4 can be set based on the imagined deformation pattern. For example, the part of the front side beam 3 that is closest to the manifold cover 25 during a vehicle V collision can be used as the fixing part 32. In this case, the fluid hose 4 can be more reliably positioned between the front side beam 3 and the manifold cover 25 during a collision.

[0052] In the above embodiment, the power unit 2 has a manifold cover 25 on the right side, and the liquid hose 4 is disposed between the front side beam 3 on the right side of the vehicle V and the power unit 2 in the vehicle width direction, but it is not limited to this. For example, the power unit 2 may also have a manifold cover 25 on the left side, and the liquid hose 4 may be disposed between the front side beam 3 on the left side of the vehicle V and the power unit 2 in the vehicle width direction.

[0053] In the above embodiment, the drive chamber DR carrying the power unit 2 is located at the front VF of the vehicle V, that is, the power unit protection structure 1 is located at the front VF of the vehicle V, but it is not limited to this. For example, the drive chamber DR may also be located at the rear of the vehicle V, or in the middle between the front VF and the rear. When the drive chamber DR is located at the rear of the vehicle V, the liquid hose 4 is provided in the vehicle width direction between the power unit 2 and the rear side beam located at the rear of the vehicle V. By applying the structure of the front side beam 3 to the rear side beam, the power unit protection structure 1 can be realized, and the same effect as the above embodiment can be achieved.

[0054] In the above embodiments, the power unit 2 includes an electric motor 22 and an inverter 23, but it may also include an internal combustion engine.

[0055] In the above embodiments, the materials of each component are not particularly limited, as long as they are materials that can perform the functions of each component. For example, the front side beam 3 can also be formed of a material other than steel plate. The housing 21 and manifold cover 25 of the power unit 2 can also be formed of materials other than metal, such as resin, fiber-reinforced resin, plastic, etc. The outer cylinder 4a of the liquid hose 4 can be formed of EPDM rubber, but it can also be formed of other rubbers, resins other than rubber, etc. The clamp 44 can also be formed of materials other than resin, such as plastic, rubber, metal, etc.

[0056] In the above embodiments, there are no particular limitations on the means by which the components are fixed to each other, as long as the means are able to fix the components to each other in a way that meets the required conditions. For example, the fixing of the motor-side busbar 22a and the inverter-side busbar 23a is not limited to bolt fastening, and other fixing means (threaded fixing, welding, bonding, etc.) can also be used. The fixing of the outer cylinder 4a of the liquid hose 4 to the front side beam 3 can also be done by fixing means other than the clip 44 (fixing via bracket, bonding, etc.).

[0057] In the above embodiments, the shape and quantity of each component are not particularly limited, as long as they meet the requirements of each component. For example, the outer cylinder 4a of the liquid hose 4 can be a cylindrical shape with a circular cross-section, an elliptical cross-section, or a cylindrical shape with a rectangular cross-section. The opening 24a of the housing 21 and the manifold cover 25 can also have shapes other than a generally rectangular shape with rounded corners when viewed from above. In addition, the number of manifold fixing bolts 24b and cover fixing bolts 25a is not limited to the number shown in the figure.

[0058] The present invention has been described above according to the embodiments and their variations, but the present invention is not limited to these descriptions and various modifications and improvements can be made, which will be obvious to those skilled in the art.

[0059] Explanation of reference numerals in the attached figures

[0060] 1: Vehicle power unit protection structure

[0061] 2: Power Unit

[0062] 22a: Motor-side busbar

[0063] 23a: Inverter-side busbar

[0064] 24: Busbar connection section (connection section)

[0065] 24a: Opening

[0066] 25: Busbar cover (protected component)

[0067] 3: Front side beam (side beam)

[0068] 4: Liquid hose (radiator hose)

[0069] 45: Overlapping areas

[0070] 5: Radiator

[0071] 51a: Outlet (Connection Port)

[0072] 52: Storage tank

[0073] 6: Storage battery

[0074] V: Vehicle

Claims

1. A protection structure for a vehicle's power unit, characterized in that, have: The side beam of the vehicle; The power unit, mounted on the vehicle, has protected components arranged opposite the side beam in the vehicle width direction; A liquid hose, which connects to the vehicle's radiator. At least a portion of the liquid hose is disposed between the side beam and the protected component, and overlaps both the side beam and the protected component when viewed from the side of the vehicle.

2. The power unit protection structure for a vehicle according to claim 1, characterized in that, The liquid hose is fixed to the side beam.

3. The power unit protection structure for a vehicle according to claim 1 or 2, characterized in that, The liquid hose is connected to the vehicle's liquid storage tank.

4. The power unit protection structure for a vehicle according to any one of claims 1 to 3, characterized in that, The liquid hose is connected to the radiator port located above the side beam, forming a flow path between the battery and the radiator located below the side beam.

5. The power unit protection structure for a vehicle according to any one of claims 1 to 4, characterized in that, The protected component is a cover that blocks the opening at the connection between the motor-side busbar and the inverter-side busbar of the power unit, which allows access to the unit.

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