Energy storage system for a vehicle equipped with at least one electric motor

Abstract

To provide a lightweight, easy-to-manufacture, and cost-effective power storage system for a vehicle.SOLUTION: A power storage system 6 includes a container 7 with a lower wall 8 and a plurality of modules 10 housed inside a container and mounted directly on the lower wall, each of the modules includes a group of electrochemical cells and two containment walls, these two containment walls are perpendicular to the lower wall of the container, are arranged parallel to each other on both sides of the pack of electrochemical cells such that the pack of electrochemical cells is clamped between them, each of the containment walls has at least one tubular bond, is secured to the lower wall, projects vertically from this lower wall, and is provided with a plurality of locking elements 17 that engages with the bond.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This patent application claims priority from Italian Patent Application No. 102020000026545, filed November 6, 2020, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to an energy storage system for a vehicle equipped with at least one electric motor. [Background technology]

[0003] A vehicle can have one or more electric motors only (in which case the drive is electric only), or one or more electric motors in combination with a thermal motor (in which case the drive can be electric only, thermal only, or a hybrid).

[0004] The electric motor(s) are mechanically connected to the drive wheels and electrically connected to a power storage system through the intermediary of a static power converter.

[0005] Energy storage systems consist of electrochemical cells (usually with a pouch or prismatic structure) connected together in series (to increase the overall voltage) and these cells are usually connected together in parallel (to increase the overall current strength). Energy storage systems can be quite large in size and very heavy (especially in the case of dedicated electric drives, where the weight of the energy storage system can exceed 500 kg).

[0006] In more modern vehicles, the energy storage system is designed to be flat and (relatively) thin, so that it can be installed inside the floor. In this configuration, the energy storage system comprises a container having a bottom wall (forming the bottom of the vehicle facing the road), a top wall, and side walls perpendicular to and connecting the bottom and top walls. Inside the container, various groups of electrochemical cells are arranged, each forming a corresponding module.

[0007] This arrangement makes the energy storage system an integral part of the vehicle floor and is therefore designed to help provide resistance and rigidity to the floor. To improve the mechanical performance of the energy storage system, it is known to arrange within the container a series of vertically arranged struts and a series of horizontally arranged cross members to create an alveolar structure having a series of alveoli, each adapted to contain a corresponding module (i.e., a corresponding group of cells). However, the provision of struts and cross members significantly increases weight and bulk.

[0008] Patent document 1 describes a power storage system for a vehicle that includes a plurality of battery modules arranged next to each other and mounted on a base plate, and in order to connect the battery modules to the base plate, each battery module includes a tubular connector and a cable into which a respective bolt is inserted that screws into a threaded hole provided in the base plate. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2018114961(A1) Summary of the Invention

[0010] The object of the present invention is to provide an energy storage system for a vehicle with at least one electric motor, said energy storage system being lightweight and at the same time easy and cost-effective to manufacture.

[0011] According to the invention, an energy storage system for a vehicle comprising at least one electric motor is created in accordance with what is claimed in the accompanying claims.

[0012] These claims describe preferred embodiments of the invention and form an integral part of this specification. [Brief explanation of the drawings]

[0013] The present invention will now be described with reference to the accompanying drawings, which show non-limiting exemplary embodiments thereof. [Figure 1] 1 is a schematic plan view of an electrically propelled road vehicle equipped with a power storage system made in accordance with the present invention; [Figure 2] 2 is an exploded perspective view of the vehicle energy storage system of FIG. 1 with parts removed for clarity. [Figure 3] FIG. 3 is a perspective view of a module in the power storage system of FIG. 2. [Figure 4] FIG. 3 is a perspective view of a module in the energy storage system of FIG. 2 with parts removed for clarity. [Figure 5] FIG. 3 is a perspective view of a container in the power storage system of FIG. 2 with parts removed for clarity. [Figure 6] FIG. 6 is a plan view of the container of FIG. 5 with parts removed for clarity. [Figure 7] 7 is a cross-sectional view of several adjacent modules in the energy storage system of FIG. 2 taken along line VII-VII. DETAILED DESCRIPTION OF THE INVENTION

[0014] In FIG. 1, reference numeral 1 indicates as a whole an electric propulsion vehicle with four drive wheels 2 (two front drive wheels 2 and two rear drive wheels 2).

[0015] The vehicle 1 comprises an electric powertrain system 3 arranged in a front position (i.e., connected to the two front drive wheels 2) and an electric powertrain system 3 arranged in a rear position (i.e., connected to the two rear drive wheels 2), which is structurally completely identical to the electric powertrain system 3 arranged in the front position and is mechanically completely independent and separated from the electric powertrain system 3 arranged in the front position.

[0016] According to another embodiment not shown, the vehicle 1 is equipped with a single electric powertrain system 3 (located in a front position or in a rear position) and therefore has only two drive wheels 2; in this embodiment, the vehicle 1 may further be equipped with a thermal powertrain system connected to the drive wheels 2 that do not receive motion from the electric powertrain system 3.

[0017] Each electric powertrain system 3 comprises a reversible electric machine 4 (i.e., capable of functioning both as an electric motor that absorbs electrical energy and generates mechanical drive torque, and as a generator that absorbs mechanical energy and generates electrical energy) with a respective shaft and a pair of transmissions 5 that connect the electric machine 4 (i.e., the shaft of the electric machine 4) to the corresponding drive wheels 2 without the intervention of any clutches.

[0018] Each of the electric machines 4 is driven by a corresponding AC / DC static power converter (i.e., inverter) connected to a power storage system 6 equipped with a chemical battery, i.e., each DC-AC static power converter is bidirectional and includes a DC side connected to the power storage system 6 and a three-phase AC side connected to the corresponding electric machine 4.

[0019] According to the content shown in FIG. 2, the shape of the power storage system 6 is flat and (relatively) thin so that it can be built inside the floor of the vehicle 1.

[0020] The energy storage system 6 comprises a container 7 having a lower wall 8 (forming the bottom of the vehicle 1 facing the road surface and obviously oriented horizontally), an upper wall (not shown and oriented horizontally), and side walls 9 (oriented horizontally) perpendicular to the lower and upper walls 8 and connecting the lower and upper walls 8 to each other.

[0021] The power storage system 6 comprises a plurality of modules 10 (specifically, 15 modules 10), each of which is disposed within a container 7, is (initially) separated and independent from the other modules 10, and houses within it a group of parallelepiped-shaped (i.e., having a pouch structure or a prismatic structure) electrochemical cells 11 (shown in FIG. 4 ). In the same module 10, the electrochemical cells 11 may be electrically connected to each other only in series or both in series and in parallel. The various modules 10 may be electrically connected to each other in series and / or in parallel.

[0022] 3 and 4, each module 10 includes a group of parallelepiped-shaped electrochemical cells 11 contained in a removable case. Each case includes two containment walls 12 that are perpendicular to the bottom wall 8 of the container 7 and are arranged parallel to each other on either side of the group of electrochemical cells 11 so as to clamp a pack of electrochemical cells 11 between them. Furthermore, each case includes two top walls 13 that are arranged perpendicular to both the two containment walls 12 and the bottom wall 8 of the container 7. Finally, each case includes a bottom wall 14 and a top wall 15 that are arranged perpendicular to the two containment walls 12 and parallel to the bottom wall 8 of the container 7; specifically, the bottom wall 14 of each case rests on the bottom wall 8 of the container 7.

[0023] The bottom wall 14 and / or top wall 15 of each case may contain a liquid heat exchanger used to condition (ie, cool or warm) the group of electrochemical cells 11 .

[0024] In either case, the containment walls 12 are the most mechanically robust (resistant) components, i.e., they have a higher mechanical robustness (resistance) than the head walls 13 of the lower and upper walls 14 and 15. The high mechanical robustness (resistance) of the containment walls 12 is immediately apparent from inspection of Figure 4, in that the walls 13-15 are essentially relatively thin, flat sheets, whereas the containment wall 12 is thicker and further comprises reinforcing ribs having relevant dimensions.

[0025] According to a preferred embodiment, each module 10 includes tie rods that press two corresponding containment walls 12 toward each other, thereby compressing and clamping the group of electrochemical cells 11 therebetween with a predetermined clamping force (and to the extent necessary for good operation of the electrochemical cells 11 when the electrochemical cells 11 are pouch-shaped).

[0026] According to a preferred embodiment shown in the accompanying figures, the power storage system 6 is configured to be mounted on the vehicle 1 so that the housing walls 12 of the modules 10 are arranged transversely to the forward direction D (shown in Figure 1) of the vehicle 1, i.e., when the power storage system 6 is mounted on the vehicle 1, all of the housing walls 12 of the modules 10 are arranged transversely (i.e., perpendicular to the forward direction D of the vehicle 1).

[0027] Each containment wall 12 comprises a series of tubular couplings 16, each having a central through cavity passing laterally through the coupling 16 (i.e. drilled through the center of the coupling 16). In the preferred embodiment shown in the accompanying figures, the couplings 16 have a cylindrical shape (and therefore their central cavities also have a cylindrical shape).

[0028] 5, the power storage system 6 comprises a plurality of cylindrical locking elements 17 fixed to the bottom wall 8 of the container 7 and protruding vertically from the bottom wall 8 (the locking elements 17 are therefore vertically oriented). The locking elements 17 are configured to engage with corresponding coupling bodies 16, i.e., to engage with the central cavities (without any associated gaps) of the corresponding coupling bodies 16.

[0029] According to a preferred embodiment, each of the locking elements 17 consists of a stud threaded at both ends, the lower end of each locking element 17 being threaded into a blind threaded hole 18 (shown in FIG. 7) formed through the bottom wall 8 of the container 7, while the upper end of each locking element 17 is engaged with a nut 19 (shown in FIG. 7) that is threaded into the corresponding locking element 17 and tightened to press at least one corresponding coupling 16 against the bottom wall 8 of the container 7 (i.e., to maintain the corresponding module 10 pressed against the bottom wall 8 of the container 7 with a given force).

[0030] According to what is shown in FIG. 7, the bottom wall 8 of the container 7 has a reinforcing element in the area of ​​the blind screw hole 18 .

[0031] 3, each of the containment walls 12 has several connectors 16 located both at the edge regions of the containment wall 12 and between the edges of the containment wall 12. Specifically, in the embodiment shown in FIG. 3, each of the containment walls 12 includes two connectors 16 located (laterally) at the edge regions of the containment wall 12 and another two connectors 16 located (centrally) between the edges of the containment wall 12, i.e., each of all the containment walls 12 has four connectors 16, two located (laterally) at the sides of the containment wall 12 and two located (centrally) between the edges of the containment wall 12.

[0032] 7, two adjacent modules 10 are aligned and overlap each other, and both have at least two corresponding coupling bodies 16 that engage with the same locking element 17, i.e., the same locking element 17 engages with the coupling body 16 of one module 10 and also with the coupling body 16 of the other adjacent module 10. As a result, the two coupling bodies 16 that engage with the same locking element 17 are arranged at different positions along the locking element 17, i.e., vertically staggered so as to be coaxial with each other (the locking elements 17 are arranged vertically).

[0033] According to what is shown in FIG. 3, each of the containing walls 12 has two recesses 20 that mirror the shape of the coupling bodies 16 inversely and accommodate the coupling bodies 16 of the adjacent containing walls 12 (as shown in FIG. 7), thereby forming an interlocking connection.

[0034] That is, the housing wall 12 has at least one first coupling body 16 (actually two in the illustrated embodiment), at least one first recess 20 that mirrors the shape of the coupling body 16 in an inverse manner and is coaxial with the first coupling body 16, and a second housing wall 12 adjacent to and mated with the first housing wall 12, having at least one second coupling body 16 (actually two in the illustrated embodiment), and at least one second recess 20 that mirrors the shape of the coupling body 16 in an inverse manner and is coaxial with the second coupling body 16; when the power storage system 6 is mounted, each of the first coupling bodies 16 of the first housing wall 12 engages with a corresponding second recess 20 of the second housing wall, and similarly, each of the second coupling bodies 16 of the second housing wall 12 engages with a corresponding first recess 20 of the first housing wall 12, thereby forming an interlocking connection (shown in FIG. 7 ).

[0035] As mentioned above, the first coupling bodies 16 of the first storage wall 12 are vertically staggered relative to the corresponding second coupling bodies 16 of the second storage wall 12 so that the two coupling bodies 16 can be coaxial with each other and, as a result, can engage with the same locking element 17.

[0036] That is, each of the containing walls 12 has, for each coupling body 16 disposed between the edges of the containing wall 12, a corresponding recess 20 that inversely replicates the shape of the coupling body 16 and is coaxial with the coupling body 16.

[0037] Also visible in FIG. 2 are the rivets 21 connected to the bottom wall 8 of the container 7 and required for fastening the sub-base.

[0038] These embodiments described herein may be combined with one another without departing from the scope of protection of the present invention.

[0039] The above-described power storage system 6 has many advantages.

[0040] Firstly, the power storage system 6 allows it to contribute in relation to the mechanical resistance and robustness of the floor of the vehicle 1 .

[0041] Furthermore, the above-described power storage system 6 has no internal reinforcing elements (i.e., no struts or cross members), and therefore has a significantly reduced weight compared to similar known power storage systems 6.

[0042] Finally, the cost and manufacturing complexity of the above power storage system 6 is relatively reduced. [Explanation of symbols]

[0043] 1 vehicle 2 wheels 3 Powertrain System 4 Electrical Machinery 5. Transmission 6. Energy storage systems 7 Container 8 Lower Wall 9 side wall 10 modules 11 Electrochemical Cell 12 Containment Wall 13 Head wall 14 Lower wall 15 Upper Wall 16 Conjugate 17 Rock Elements 18 screw holes 19 Nut 20 recess 21 Rivet D Forward

Claims

1. An energy storage system (6) for a vehicle (1) equipped with at least one electric motor (4), said energy storage system (6) comprising: a container (7) with a bottom wall (8); a plurality of modules (10) housed inside the container (7) and resting directly on the bottom wall (8); each of the modules (10) comprises two containing walls (12) arranged parallel to each other on either side of the group of electrochemical cells (11) and perpendicular to the bottom wall (8) of the container (7) and clamping the group of electrochemical cells (11) between them, Each of the containment walls (12) has at least one tubular connector (16); a plurality of locking elements (17) fixed to the bottom wall (8), protruding vertically from the bottom wall (8) and engaging with the coupling bodies (16); At least two adjacent modules (10) are aligned and overlap each other and have two corresponding coupling bodies (16) that both engage with the same locking element (17), each of said locking elements (17) consisting of a stud threaded at both ends; a plurality of nuts (19) each screwed onto a corresponding locking element (17) and tightened to press at least one corresponding coupling body (16) against the bottom wall (8) of the container (7); The lower end of each of the locking elements (17) is screwed into a blind threaded hole (18) formed through the lower wall (8) of the container (7); The upper end of each of the locking elements (17) engages with a nut (19), which is screwed onto the locking element (17) and tightened to press at least one corresponding coupling body (16) against the bottom wall (8) of the container (7), thereby maintaining the corresponding module (10) pressed against the bottom wall (8) of the container (7) with a given force. An energy storage system (6) for a vehicle (1).

2. 2. The power storage system (6) according to claim 1, wherein the same locking element (17) engages with the coupling bodies (16) of a module (10), and the coupling bodies (16) of another adjacent module (10) that consequently engage with the same locking element (17) are arranged at different positions along the locking element (17), i.e., vertically staggered so as to be coaxial with each other.

3. The energy storage system (6) according to claim 1 or 2, wherein two coupling bodies (16) that engage with the same locking element (17) are arranged at different positions along the locking element (17).

4. 4. The power storage system (6) according to claim 1, wherein at least one of the storage walls (12) has a recess (20) that inversely replicates the shape of the coupling body (16) and receives the coupling body (16) of an adjacent storage wall (12), thereby forming an interlocking coupling.

5. The first containing wall (12) has at least one first connecting body (16) and at least one first recess (20) that inversely replicates the shape of the connecting body (16) and is coaxial with said first connecting body (16), a second storage wall (12) adjacent to and mating with the first storage wall (12) having at least one second connecting body (16) and at least one second recess (20) that inversely reproduces the shape of the connecting body (16) and is coaxial with the second connecting body (16); the first coupling body (16) of the first containing wall (12) engages with the second recess (20) of the second containing wall (12); 5. The power storage system (6) according to claim 1, wherein the second coupling (16) of the second storage wall (12) engages with the first recess (20) of the first storage wall (12), thereby forming an interlocking coupling.

6. An energy storage system (6) as described in any one of claims 1 to 5, wherein the lower wall (8) of the container (7) has a plurality of threaded holes (18) into which the locking element (17) is screwed.

7. 7. The power storage system (6) according to claim 1, wherein each of the containing walls (12) has several couplings (16) arranged both in the edge region of the containing wall (12) and between the edges of the containing wall (12).

8. 8. The power storage system (6) of claim 7, wherein each of the storage walls (12) has two couplings (16) disposed in the edge regions of the storage wall (12) and another two couplings (16) disposed between the edges of the storage wall (12).

9. 9. The power storage system (6) according to claim 7 or 8, wherein the containing wall (12) has, for each connecting body (16) arranged between the edges of the containing wall (12), a corresponding recess (20) that inversely reproduces the shape of the connecting body (16) and is coaxial with the connecting body (16).

10. The power storage system (6) according to any one of claims 1 to 9, wherein each of the modules (10) includes a tie rod that presses the two corresponding containment walls (12) towards each other.

11. 11. The power storage system (6) according to claim 1, wherein each of the modules (10) includes two head walls (13) arranged perpendicular to the two storage walls (12) and having mechanical rigidity lower than that of the storage walls (12).

12. 12. The power storage system (6) according to claim 1, wherein each of the modules (10) includes a lower wall (14) and an upper wall (15) that are arranged perpendicular to the two storage walls (12) and have mechanical rigidity lower than that of the storage walls (12).

13. Four wheels (2) and at least one electric powertrain system (3) including at least one reversible electric machine (4); and an electric power storage system (6) according to any one of claims 1 to 12, configured to be mounted on the vehicle (1) so as to position the storage wall (12) transversely to a forward direction (D) of the vehicle.

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