Vehicle equipped with a lithium-ion battery combined with a compression device

Abstract

The invention relates to an electrically propelled scooter (1) having a lithium-ion battery (13) comprising at least two cells (14) placed on a floor (2) of said scooter. A rotating platform (26) covering said cells (14) is connected to a cell compression device (14). When a person mounts the scooter (1), they come into contact with the platform (26) by inertia, which can then move from a first default position in which it is tilted and the compression device (21) exerts an initial pressure on the cells (14), to a second horizontal position obtained under the weight of the person resting on it (26) and in which the compression device (21) exerts a second pressure on the cells (14) that is greater than the first. Figure 6 (for the abstract)

Description

Title of the invention: Vehicle equipped with a lithium-ion battery associated with a compression device

[0001] The present invention relates to a vehicle equipped with a lithium-ion (Li-ion) battery associated with a compression device.

[0002] During the charging of the Li-ion battery, lithium forms silicon alloys with the formula LixSi. The formation of these alloys leads to an increase in the volume of the Si particles, which can reach up to 300% of the initial volume of the silicon particles. During the discharge of the Li-ion battery, the LixSi alloys delithiate, thus reducing the size of the silicon particles. At the scale of the silicon electrode and the cell, significant, almost reversible volume variations, similar to respiration, will therefore occur during the battery's charge and discharge cycles. These volume variations over the battery's lifetime (successive charges and discharges) will cause significant mechanical stresses within the Li-ion battery. The Si particles can fracture, detach from the current collector, and / or become electronically isolated from the percolating network of the electrode.These phenomena will then lead to a degradation of battery performance. Furthermore, parasitic reactions will occur, generating an irreversible increase in volume, and therefore premature aging of the battery.

[0003] In order to limit the increase in the volume of the Li-ion battery due to the formation of silicon alloys generated during a charging phase of said battery, a compression device on board the vehicle is associated with said battery to exert a compression force.

[0004] Application DE102009035482 A1 describes a lithium-ion electric battery for a motor vehicle comprising a plurality of battery cells fixed between two end plates and forming a cell stack. More particularly, the lithium-ion battery comprises several battery cells, inserted between two end plates thus forming a cell stack. A unit applies a pressure charge to the cell stack in a specific stacking direction by means of a spring and an active actuator. The actuator is specifically controlled during certain phases of the vehicle's life, based on the life / pressure characteristic diagram, or based on measured temperature and / or pressure values ​​in the cell stack, said values ​​depending on the charge / discharge cycles.This solution is complex, combining sensors, actuators, a control device and a power source.

[0005] A vehicle according to the invention comprises a Li-ion battery and a battery compression device whose operation is simplified, in particular freeing itself from any energy source for triggering specifically designed to ensure this function.

[0006] To remove any ambiguity, the terms "electrochemical cells" and "cells" are equivalent.

[0007] The invention relates to an electric propulsion vehicle having a battery comprising at least two cells placed side by side and in contact with each other on a floor of said vehicle, said at least two cells forming an assembly of which a first end is in contact with a first stop mounted fixed relative to said floor, said vehicle comprising a compression device for said assembly of cells, said device being included between a second end of said assembly and a second stop mounted fixed relative to said floor.

[0008] According to the invention, the compression device comprises a movable platform covering at least partially the two cells. This movable platform can move from a first position, in which the device exerts an initial pressure on the cells, to a second position obtained under the weight of a person leaning on it, in which the device exerts a second pressure on the cells that is greater than the first. The principle of a vehicle according to the invention is to have a set of electrochemical cells in contact with each other. One end of each cell is in contact with a first fixed stop, and the other end of each cell is subjected to a variable pressure depending on whether or not a person is leaning on the movable platform covering the cells.Indeed, by default, the compression device exerts an initial pressure on the electrochemical cells. This pressure is transformed, thanks to the characteristics of the compression mechanism, into a second, higher pressure when a person applies pressure to the moving platform. Under the weight of this person, the platform lowers, ensuring good positional stability. The person thus advantageously replaces a motorized triggering element for the compression mechanism, which would represent an additional cost and increase the vehicle's weight. To move the moving platform from the first to the second position, the person can stand on the platform or sit on a seat with at least one leg attached to the moving platform. The vehicle could, for example, be a scooter.

[0009] According to one possible feature of the invention, the compression device comprises a connecting rod mechanism and a spring originating on the connecting rod mechanism, the spring bearing against the second end of the assembly of cells, the moving plate being connected to the connecting rod mechanism in such a way that: - when the moving plate is in its first position, the spring produces the first force, and - when the moving platform is in its second position, the spring, which is compressed under the effect of the person's weight, produces the second force.

[0010] According to one possible feature of the invention, the vehicle includes a sliding plate mounted on the floor and inserted between one end of the spring and the other end of the cell assembly. In this way, this sliding plate allows the spring to exert a homogeneous and widespread compression on the electrochemical cells of the electric battery. Preferably, this sliding plate is a plate whose dimensions are greater than or equal to those of the cells.

[0011] According to one possible feature of the invention, the movable platform is mounted to pivot about a horizontal axis of rotation and can move from the first position to the second position by means of a rotation about said axis. This means of movement by rotation is efficient while not requiring any significant clearance space, as might be the case, for example, with movement by translation. By moving by pivoting, the movable platform occupies a constant space.

[0012] According to one possible feature of the invention, the lithium-ion battery is arranged substantially horizontally and comprises several cells aligned along a longitudinal axis of said battery, the first and second ends of the assembly forming the cells being along said longitudinal axis. In this way, all the cells of the electric battery are affected by the pressure generated by the compression device.

[0013] According to one possible feature of the invention, the second stop is constituted by an inverter. Preferably, the inverter has a wall on which the connecting rod mechanism is fixed. Advantageously, this wall extends in a vertical plane.

[0014] According to one possible feature of the invention, the horizontal axis of rotation of the movable plate is placed adjacent to the inverter such that said inverter is inserted between the connecting rod mechanism and said axis of rotation, said movable plate covering all the battery cells, the spring, the connecting rod mechanism, and the inverter. In addition to acting as an actuating lever moved by a person's weight to activate the compression device, the movable plate also acts as a protective separator, preventing said person from coming into direct contact with the various electrochemical cells and the elements directly connected to said cells. By covering said cells and said by incorporating these elements, it will also improve the aesthetics of the vehicle.

[0015] According to one possible feature of the invention, the connecting rod mechanism comprises a first connecting rod mounted articulated to a wall of the inverter, a second connecting rod mounted articulated to the plate, and a third connecting rod mounted articulated to the spring, said three connecting rods being arranged in a star pattern and being mounted articulated to each other about a central axis of said star pattern. When it is stated that the second connecting rod is mounted articulated on the moving plate, the term "on" is a generic term. In reality, this second connecting rod is located under said moving plate and is therefore mounted under said moving plate.

[0016] According to a possible feature of the invention, the first stop is constituted by a charger against which the first end of the assembly forming the cells rests.

[0017] According to one possible feature of the invention, the vehicle is a scooter having a front wheel and a rear wheel, the movable platform serving as a support surface for the feet of the person riding the scooter. In this way, each time a person mounts the scooter to be transported by it to a predefined destination, they lower the movable platform to a horizontal position, thereby exerting high compression on the battery's electrochemical cells. The movable platform replaces the scooter's floorboards to support the person riding it. This person thus lowers the movable platform while in a natural, upright position on the scooter. They will therefore not have to perform complicated and awkward contortions to lower the movable platform.

[0018] According to one possible feature of the invention, the scooter's deck is arranged substantially horizontally and the battery cells are aligned along a longitudinal axis of said deck, the first end of the assembly formed by said cells being located on the side of said deck closest to the front wheel and the second end of said assembly being located on the side of said deck closest to the rear wheel, an electric drive motor being housed inside the rear wheel. The motor's power supply mechanism is confined to the perimeter of the scooter's deck.The presence of electrochemical cells, the compression device and other elements inherent to the propulsion of the scooter must not impair its use, either by reducing the space reserved for the feet of the person seated on the scooter, or by creating inhospitable terrain likely to compromise the comfort of said person riding the scooter.

[0019] A vehicle according to the invention has the advantage of possessing a device for compressing the electrochemical cells of a lithium-ion battery, not requiring No specific triggering device is required; the weight of the person inside the vehicle performs this function. This results in a shorter manufacturing time for the vehicle and therefore lower costs. Furthermore, this compression system is efficient yet compact, and thus has no negative impact on the vehicle by interfering with other functions.

[0020] A detailed description of a preferred embodiment of a vehicle according to the invention is given below, with reference to the following figures:

[0021] [Fig-1] Fig. 1 is a side view of a scooter according to the invention,

[0022] [Fig.2] Fig.2 is a perspective view of a scooter according to the invention,

[0023] [Fig.3] Fig.3 is a perspective view of one side of a scooter according to the invention, with the movable platform having been removed,

[0024] [Fig.4] Fig.4 is a perspective view from another side of a scooter according to the invention, with the movable platform having been removed,

[0025] [Fig.5] Fig.5 is a perspective view of a scooter according to the invention, showing in detail its propulsion system,

[0026] [Fig.6] Fig.6 is a side view of an area of ​​a scooter according to the invention, showing a device for compressing the electrochemical cells of the battery into a default position,

[0027] [Fig.7] [Fig.7] is a view of the area of ​​[Fig.6], showing the communication device pressure of the battery's electrochemical cells in an activated position,

[0028] With reference to Figures 1 and 2, a scooter 1 according to the invention comprises a rectangular platform 2, a front wheel 3, a rear wheel 4, an electric propulsion system 5, and handlebars 15. The platform 2 is elongated and consists of a horizontal rectangular wall. The handlebars 15 comprise an elongated main stem 6, of which: -a first end consists of a secondary rod 7 having two handles 8, 9 at its two ends considered along a longitudinal axis of said secondary rod 7, -a second end includes a fork in which the front wheel 3 is mounted.

[0029] It should be noted that the secondary rod 7 is perpendicular to and centered on the main rod 6. The handlebar 15 is mounted at the front of the floor 2 by means of an inclined arm projecting forward from said floor 2. This inclined arm has an upstream end which is fixed to the floor 2 and a downstream end through which passes the main rod 6 of the handlebar 15, said downstream end corresponding to the most forward part of the inclined arm. Once the handlebar 15 has been mounted on the scooter 1, the front wheel 3 represents its lowest part and the secondary rod 7 represents its highest part. At the rear of the floor 2 is placed a rear fork 90 composed of two horizontal arms 10, 11 originating in a rear area of ​​the floor 2 and extending towards the rear of said floor 2. These two arms 10, 11 are placed at the same height and are spaced apart to allow the rear wheel 4 to be mounted between said two arms 10, 11. The terms "front" and "rear" applied to the floor 2 must be considered with respect to a longitudinal axis of the floor 2.

[0030] With reference to figures 2, 3, 4 and 5, the electric propulsion system 5 includes an electric motor 12 which is housed in the rear wheel 4. Once this electric motor 12 has been activated, it triggers a rotation of the rear wheel 4 which then moves the scooter 1 forward.

[0031] With reference to Figures 3, 4, 5, 6 and 7, the propulsion system 5 of the scooter 1 comprises a lithium-ion electric battery 13 consisting of a set of several electrochemical cells 14. These electrochemical cells 14 may, for example, be prismatic or of the Pouch type. They each have a parallelepiped shape and are placed side by side, such that two consecutive electrochemical cells 14 are in contact with each other. The set of these electrochemical cells 14 has an elongated parallelepiped shape, and is placed on the floor 2 of the scooter 1 so that a longitudinal axis of this set of electrochemical cells 14 is parallel to a longitudinal axis of said floor 2. These cells 14 extend over at least 70% of the width of the floor 2 and will constitute a step wide enough for a person to stand stably on said cells 14.The assembly of these electrochemical cells 14 comprises a first front end 16 located on the side of the handlebar 15, which bears against a first stop formed by a charger 17 delimited by a parallelepiped-shaped housing. This charger 17 is fixed to the floor 2 and has a flat face extending along a transverse and vertical plane of said floor 2. In this way, the cell 14 located furthest forward of the assembly of cells 14 has an end face that bears against the flat face of the charger 17. The assembly of these electrochemical cells 14 also comprises a second rear end 18 located on the side of the rear wheel 4, against which a movable plate 19 bears. It should be noted that the first end 16 and the second end 18 of the assembly of electrochemical cells 14 are to be considered with respect to a longitudinal axis of said assembly.A rear area of ​​the floor 2 supports an inverter 20 delimited by a parallelepiped-shaped box and located behind the second end 18 of the set of electrochemical cells 14.

[0032] Referring to [Fig.4], the scooter 1 includes at least two connection plates 34 capable of handling high power and battery control signals.

[0033] With reference to Figures 5, 6 and 7, a compression device 21 of the electrical cells The electrochemical cells 14 of the lithium-ion battery 13 are inserted between the moving plate 19 located behind the second end 18 of the assembly of electrochemical cells 14 and a face 22 of the inverter 20 extending in a vertical and transverse plane of the floor 2. This compression device 21 comprises a mechanism of three connecting rods 23, 24, 25, among which: -a first connecting rod 23 which is mounted articulated on the vertical face 22 of the inverter 20 around a first axis 28, -a second connecting rod 24 which is mounted articulated on a movable plate 26 around a second axis 29, and -a third connecting rod 25 ending in a vertical wall 30 which is in contact with a spring 27 which itself bears against the movable plate 19. This third connecting rod 25 is mounted articulated on said spring 27 around a third axis 31. The spring 27 is spiral and extends horizontally above the floor 2, bearing both against the movable plate 19 which is in contact with the second end of the assembly forming the electrochemical cells 14, and the vertical wall 30 ending the third connecting rod 25.

[0034] Referring to figures 6 and 7, these three connecting rods 23, 24, 25 are arranged in a star shape and are mounted articulated together around a central axis 32 placed at the center of the star pattern formed by the three connecting rods 23, 24, 25.

[0035] Referring to Figures 1 and 5, the movable platform 26 is flat and rectangular in shape, and covers all the elements supported by the floor 2, namely: the charger 17, the set of electrochemical cells 14, the moving plate 19, the mechanism of three connecting rods 23, 24, 25, and the inverter 20. The movable platform 26 therefore has substantially the same dimensions as those of the floor 2 and is mounted to rotate about a horizontal axis of rotation 33, extending in a transverse direction from the floor 2. This axis of rotation 33 is located behind the housing representing the inverter 20 and at a certain height from it relative to the floor 2, against a face that is parallel to the vertical face 22 of said inverter 20 to which the first connecting rod 23 is fixed.The electric motor 12, which is placed in the rear wheel 4, is connected to the inverter 20 by electrical wires passing in particular through the two arms 10, 11 of the rear fork 90.

[0036] Referring to [Fig. 6], the movable platform 26 is by default inclined above the cells 14, along the floor 2, with a front portion of said movable platform 26 being slightly raised relative to a rear portion thereof. The compression device 21 then exerts default pressure on the electrochemical cells 14 of the battery 13. The term "default" means "in the absence of external stress." Therefore, by default, since the battery 13 is not in use, it is in the charging phase.

[0037] Referring to [Fig. 7], a person wishing to use the scooter 1 to travel to a given destination will step onto the inclined platform 26, and, by means of their weight, will cause said platform 26 to lower by means of a rotation of the latter around its axis of rotation 33. The platform 26 then adopts a horizontal position above the cells 14, causing a movement of each of the connecting rods 23, 24, 25 constituting the connecting rod mechanism of the compression device 21. The compression device 21 will then exert a pressure on the electrochemical cells 14, which will be greater than the default pressure exerted on said cells 14. Since the first end of the assembly of cells 14 is against the charger 17, the pressure exerted by the compression device 21 on the second end of said assembly puts the cells 14 into a state of compression.The scooter 1 is in a rolling phase and therefore in a battery discharge phase. The pressure exerted by the compression device 21 during this rolling phase of the scooter 1 (and therefore during a discharge phase of the battery 13) will then accompany the lithiation of the Li,Six alloys, and will thus preserve the lifespan of the cells 14. During the charging phase of the battery 13, and therefore in the absence of a person exerting pressure by inertia on the platform 26, there is no longer any pressure, but only a pre-compression, promoting the lithiation of the Li,Six alloys.

Claims

Demands

1. An electrically powered vehicle (1) having a battery (13) comprising at least two cells (14) placed side by side and in contact with each other on a floor (2) of said vehicle, said at least two cells (14) forming an assembly of which a first end (16) is supported against a first stop mounted fixed relative to said floor (2), said vehicle comprising a compression device (21) for said assembly of cells (14), said device (21) being included between a second end (18) of said assembly and a second stop mounted fixed relative to said floor (2), characterized in that the compression device (21) comprises a movable plate (26) covering at least partially the two cells (14), and in that said movable plate (26) can move from a first position for which the device (21) produces a first pressure force on said cells (14),to a second position obtained under the effect of the weight of a person leaning on it (26) and for which the device (21) produces a second pressure force on said cells (14) which is greater than the first force.

2. Vehicle according to claim 1, characterized in that the compression device (21) comprises a linkage mechanism (23, 24, 25) and a spring (27) originating on the linkage mechanism (23, 24, 25), the spring (27) bearing against the second end (18) of the cell assembly (14), the movable plate (26) being connected to the linkage mechanism (23, 24, 25) such that: - when the movable plate (26) is in its first position, the spring (27) produces the first force, and - when the movable plate (26) is in its second position, the spring (27), which is compressed under the effect of the person's weight, produces the second force.

3. Vehicle according to claim 2, characterized in that it comprises a plate (19) mounted sliding on the floor (2) and which is inserted between one end of the spring (27) and the second end (18) of the set of cells (14).

4. A vehicle according to any one of claims 1, 2 or 3, characterized in that the movable platform (26) is mounted pivotally about a horizontal axis of rotation (33) and can move from the first position to the second position by means of a rotation around said axis (33).

5. Vehicle according to claim 4, characterized in that the battery (13) is arranged substantially horizontally and comprises several cells (14) aligned along a longitudinal axis of said battery (13), and in that the first end (16) and the second end (18) of the assembly forming the cells (14) are substantially along said longitudinal axis.

6. Vehicle according to claim 5, characterized in that the second stop is constituted by an inverter (20).

7. Vehicle according to claims 2 and 6, characterized in that the horizontal axis of rotation (33) of the movable plate (26) is placed adjacent to the inverter (20) so that said inverter (20) is inserted between the connecting rod mechanism (23, 24, 25) and said axis of rotation (33), said movable plate (26) covering all the cells (14) of the battery (13), the spring (27), the connecting rod mechanism (23, 24, 25) and the inverter (20).

8. Vehicle according to claim 2 and any one of claims 4 to 7, characterized in that the connecting rod mechanism comprises a first connecting rod (23) mounted articulated to a wall (22) of the inverter (20), a second connecting rod (24) mounted articulated to the plate (26) and a third connecting rod (25) mounted articulated to the spring (27), and in that said three connecting rods (23, 24, 25) are arranged in a star and are mounted articulated to each other about a central axis (32) of said star pattern.

9. Vehicle according to any one of claims 1 to 8, characterized in that the first stop is constituted by a loader (17) against which the first end (16) of the assembly forming the cells (14) rests.

10. Vehicle according to any one of claims 4 to 9, characterized in that it constitutes a scooter (1) having a front wheel (3) and a rear wheel (4), and in that the movable platform (26) serves as a support surface for the feet of the person piloting said scooter (1).

11. A vehicle according to claim 10, characterized in that the floor (2) of the scooter (1) is arranged substantially horizontally and the cells (14) of the battery (13) are aligned along a longitudinal axis of said floor (2), and in that the first end (16) of the assembly formed by said cells (14) is located on the side of said floor (2) closest to the front wheel and the second end (18) of said assembly is located on the side of said floor (2) closest to the rear wheel, an electric drive motor (12) being housed inside the rear wheel (4).

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