Vehicle provided with a lithium-ion battery associated with a compression device

Abstract

The invention relates to an electric scooter (1) having a lithium-ion battery (13) comprising at least two cells (14) placed on a floor (2) of the scooter. A rotatable plate (26) covering the cells (14) is connected to a cell compression device (14). When a person is riding the scooter (1), they bear upon the plate (26) by inertia, allowing the plate to pass from a first default position for which it is inclined and the compression device (21) produces a first pressing force on the cells (14), to a second horizontal position obtained by the weight of the person bearing upon the plate (26) and for which the compression device (21) produces a second pressing force on the cells (14) which is greater than the first force.

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 having a lithium-ion (Li-ion) battery associated with a compression device.

[0002] When charging the Li-ion battery, lithium will form silicon alloys with the formula Li x Si. The formation of these alloys results in an increase in the volume of Si particles which can reach up to 300% of the initial volume of silicon particles. When discharging Li-ion batteries, Li alloys xSi are delithiated, thus leading to a decrease in the size of the silicon particles. At the scale of the silicon electrode and the cell, strong, quasi-reversible volume variations, similar to breathing, will therefore occur during the battery charge and discharge cycles. These volume variations over the life of the battery (successive charges and discharges) will cause strong mechanical stresses within the Li-ion battery. The Si particles can fracture, separate 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 the battery performance. In addition, 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 stack of cells. More particularly, the lithium-ion battery comprises several battery cells, inserted between two plates thus forming a stack of cells. A unit makes it possible to apply a pressure load to the stack of cells, in a stacking direction by means of a spring and using an active actuator. However, the actuator is specifically controlled during certain phases of the vehicle's service life, depending on the service life / pressure characteristic diagram, or depending on the measured temperature and / or pressure values ​​in the cell stack, said values ​​depending on the charge / discharge cycles. This solution is complex, combining in particular sensors, actuators, a control device and an energy source.

[0005] A vehicle according to the invention comprises a Li-ion battery and a device for compressing said battery, the operation of which is simplified, in particular eliminating the need for any triggering energy source specifically designed to perform this function.

[0006] For the avoidance of doubt, the terms "electrochemical cells" and "cells" are equivalent.

[0007] The subject of the invention is an electrically powered vehicle having a battery comprising at least two cells placed next to each other 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 bears against a first stop mounted fixedly relative to said floor, said vehicle comprising a device for compressing said assembly of cells, said device being between a second end of said assembly and a second stop mounted fixedly relative to said floor.

[0008] According to the invention, the compression device comprises a movable plate at least partially covering the two cells, said movable plate being able to move from a first position for which the device produces a first pressure force on said cells, to a second position obtained under the effect of the weight of a person pressing on it and for which the device produces a second pressure force on said cells which is greater than the first force. The principle of a vehicle according to the invention is to have a set of electrochemical cells in contact with each other, a first end of which is in contact with a first fixed stop and a second end of which is subjected to a variable pressure depending on whether or not a person is pressing on the movable plate covering said cells. Indeed, by default the compression device exerts a first pressure on the electrochemical cells which is transformed, thanks to the characteristics of the compression mechanism, into a second pressure which is higher than said first pressure, in the case where a person were to exert pressure on the movable platform. Under the effect of the weight of said person, the platform lowers allowing said person to ensure good positional stability. The person thus advantageously replaces a motorized triggering element of the compression mechanism which would constitute an additional source of cost and which would weigh down said vehicle. To move the movable platform from the first position to the second position, the person can stand on said platform or be seated on a seat of which at least one foot is fixed to the movable platform. The vehicle can for example be a scooter.

[0009] According to a possible characteristic of the invention, the compression device comprises a link mechanism and a spring originating on the link mechanism, the spring bearing against the second end of the cell assembly, the movable plate being connected to the link mechanism in such a way that: - when the movable plate is in its first position, the spring produces the first force, and - when the movable plate 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 a possible characteristic of the invention, the vehicle comprises a plate slidably mounted on the floor and which is inserted between one end of the spring and the second end of the set of cells. In this way, this sliding plate allows the spring to exert a homogeneous and extended 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 a possible characteristic of the invention, the movable plate is pivotally mounted around a horizontal axis of rotation and can move from the first position to the second position by means of a rotation around said axis. This means of rotational movement is efficient while not requiring any significant clearance space, as might be the case, for example, with translational movement. By moving by pivoting, the movable plate occupies a constant space.

[0012] According to a possible characteristic 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 end and the second end 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 a possible characteristic 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 a possible feature of the invention, the horizontal rotation axis of the movable plate is placed adjacent to the inverter so that said inverter is inserted between the link mechanism and said rotation axis, said movable plate covering all of the battery cells, the spring, the link mechanism and the inverter. In addition to the fact that the movable plate acts as an actuating lever moved by the weight of a person to activate the compression device, it will also act 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 elements connected to them, it will also improve the aesthetics of the vehicle.

[0015] According to a possible characteristic of the invention, the link mechanism comprises a first link mounted articulated to a wall of the inverter, a second link mounted articulated to the plate and a third link mounted articulated to the spring, said three links being arranged in a star pattern and being mounted articulated to each other around a central axis of said star pattern. When it is mentioned that the second link is mounted articulated on the movable plate, the term "on" is a generic term. In reality, this second connecting rod is placed under said movable plate and is therefore mounted under said movable plate.

[0016] According to a possible characteristic 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 a possible characteristic of the invention, the vehicle constitutes a scooter having a front wheel and a rear wheel, the movable platform serving as a support surface for the feet of the person piloting said scooter. In this way, each time a person gets on the scooter to be moved by it to a predefined destination, he pushes the movable platform to place it in a horizontal position so as to exert high compression on the electrochemical cells of the battery. The movable platform replaces the floor of the scooter to support the person who is mounted on said scooter. This person thus ensures a lowering of the movable platform while being in a standing and natural position on said scooter. He will therefore not have to engage in complicated and restrictive contortions to lower the movable platform.

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

[0019] A vehicle according to the invention has the advantage of having a device for compressing the electrochemical cells of a lithium-ion battery, requiring no specific triggering device, the weight of the person installed in the vehicle allowing this function to be performed. This results in a shorter and therefore less expensive vehicle manufacturing time. In addition, this compression device is efficient while being compact and therefore has no negative effect on the vehicle by encroaching on other functions thereof.

[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] Figure 1 is a side view of a scooter according to the invention,

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

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

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

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

[0026] [Fig. 6] Figure 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 in a default position,

[0027] [Fig. 7] Figure 7 is the view of the area of ​​Figure 6, showing the battery electrochemical cell compression device in an activated position,

[0028] Referring to Figures 1 and 2, a scooter 1 according to the invention comprises a rectangular-shaped floor 2, a front wheel 3, a rear wheel 4, an electric propulsion system 5 and a handlebar 15. The floor 2 is elongated and is constituted by a horizontal rectangular wall. The handlebar 15 includes an elongated main stem 6, including: - a first end is constituted by 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 comprises a fork in which the front wheel 3 is mounted.

[0029] It should be noted that the secondary rod 7 is perpendicular to the main rod 6 and is centered on it. The handlebar 15 is mounted at the front of the floor 2 by means of an inclined arm 8 projecting towards the front of said floor 2. This inclined arm 8 has an upstream end which is fixed to the floor 2 and a downstream end inside which passes the main rod 6 of the handlebar 15, said downstream end corresponding to the most forward part of the inclined arm 8. 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 3 is placed a rear fork 9 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 from each other 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 relative to a longitudinal axis of the floor 2.

[0030] Referring to Figures 2, 3, 4 and 5, the electric propulsion system 5 comprises 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] Referring to Figures 3, 4, 5, 6 and 7, the propulsion system 5 of the scooter 1 comprises a lithium-ion electric battery 13 comprising 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 with each other, so that two consecutive electrochemical cells 14 are in contact with each other. All of these electrochemical cells 14 have a 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 sufficiently wide for a person to be able to stand upright and stably on said cells 14. The set of these electrochemical cells 14 comprises a first front end 16 located on the side of the handlebar 15 and which comes to bear against a first stop constituted by a charger 17 delimited by a box of parallelepiped shape. 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 set of cells 14, has an end face which will come to bear against the flat face of the charger 17.The set of these electrochemical cells 14 also comprises a second rear end 18 located on the side of the rear wheel 4 and against which a movable plate 19 bears. It should be noted that the first end 16 and the second end 18 of the set of electrochemical cells 14 are to be considered relative to a longitudinal axis of said set. A rear zone of the floor 2 supports an inverter 20 delimited by a parallelepiped-shaped housing and located behind the second end 18 of the set of electrochemical cells 14.

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

[0033] Referring to Figures 5, 6 and 7, a compression device 21 for the electrochemical cells 14 of the lithium-ion battery 13 is inserted between the movable plate 19 located behind the second end 18 of the set 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 against a spring 27 which itself comes to bear 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, coming to bear 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 terminating 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 in the center of the star pattern formed by the three connecting rods 23, 24, 25.

[0035] Referring to Figures 1 and 5, the movable plate 26 is flat and rectangular in shape, and covers all of the elements which are supported by the floor 2, namely: the charger 17, all of the electrochemical cells 14, the movable plate 19, the mechanism of three connecting rods 23, 24, 25, and the inverter 20. The movable plate 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 of the floor 2. This axis of rotation 33 is placed behind the housing materializing the inverter 20 and at a certain height thereof relative to the floor 2, against a face which 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 electric wires passing in particular through the two arms 10, 11 of the rear fork 9.

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

[0037] Referring to Figure 7, a person wishing to use the scooter 1 to go to a given destination, will climb onto the inclined platform 26, and thanks to its weight, will cause a lowering of said platform 26 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 pressure exerted by default on said cells 14. Since the first end of the set of cells 14 is in abutment against the charger 17, the pressure exerted by the compression device 21 on the second end of said set, puts the cells 14 in 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 battery discharge phase 13) will then accompany the delithiation 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 plate 26, there is no longer any pressure, but only a pre-compression, promoting the lithiation of the Li,Six alloys.

Claims

[00038] Claims

1. Electrically powered vehicle (1) having a battery (13) comprising at least two cells (14) placed next to each other 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) bears against a first stop (17) mounted fixedly relative to said floor (2), said vehicle comprising a compression device (21) for said assembly of cells (14), said device (21) being between a second end (18) of said assembly and a second stop (20) mounted fixedly relative to said floor (2), characterized in that the compression device (21) comprises a movable plate (26) at least partially covering the two cells (14), and in that said movable plate (26) can pass 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 link mechanism (23, 24, 25) and a spring (27) originating on the link 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 link mechanism (23, 24, 25) in such a way 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 weight of the person, produces the second force.

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

4. Vehicle according to any one of claims 1, 2 or 3, characterized in that the movable platform (26) is pivotally mounted around a horizontal axis of rotation (33) and can move from the first position to the second position by means of 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 claim 6, characterized in that the horizontal rotation axis (33) of the movable plate (26) is placed adjacent to the inverter (20) so that said inverter (20) is inserted between the link mechanism (23, 24, 25) and said rotation axis (33), said movable plate (26) covering all of the cells (14) of the battery (13), the spring (27), the link mechanism (23, 24, 25) and the inverter (20).

8. A vehicle according to any one of claims 4 to 8, characterized in that it comprises: 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 shape and are mounted articulated to each other around a central axis (32) of said star pattern.

9. A vehicle according to any one of claims 1 to 10. 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) bears.

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

11. 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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