PRISMATIC BATTERY EQUIPPED WITH A SQUEEZE UNIT

Abstract

A prismatic battery (20) comprises: a stack (22) of prismatic battery cells (24) stacked along a reference axis (100), a housing (26) that houses the stack (22), at least one end plate (28) located inside the housing (26) at an axial end of the stack (22), and at least one stress unit comprising at least one movable stress element (34) in contact with a contact face of the end plate (28) opposite the stack (22), and at least one spring (38) applying a stress force to the stress element in the direction of the stack (22), such that the stress element (34) applies a pressure force to the end plate (28) with an axial pressure force component (36) in the direction of the stack (22). The loading unit (32) is removably attached to the housing (26) and has a frame (40) that houses the spring (38) and guides the loading element (34). (Figure 4)

Description

Title of the invention: PRISMATIC BATTERY EQUIPPED WITH A SQUEEZE UNIT technical field

[0001] The present invention relates to a prismatic battery pack, in particular for powering an electric drive motor of an electric vehicle, equipped with a stress device to compensate for the play that may accumulate over time between the battery cells of the prismatic battery pack, in particular due to a reduction in the volume of the battery cells. PREVIOUS STATE OF THE ART

[0002] A prismatic battery known as US number 11894570 comprises a housing that contains several stacks of prismatic battery cells arranged along a prismatic battery reference axis, an end plate located inside the housing and extending into a space between an end wall of the housing and an end of the prismatic battery, and a excitation device for applying a pressure force to the end plate toward the stack of prismatic battery cells. The excitation device comprises a excitation element in contact with the end plate and movable between a first and a second end position, and a spring that applies a excitation force directly or indirectly to the excitation element in the direction of the second end position.The stress-relieving device is located within the prismatic battery casing and occupies a significant amount of space unavailable for the battery cells, which is detrimental to capacity and power density. The stress-relieving device components must be individually assembled within the casing and cannot be easily mounted and disassembled. Furthermore, the pressure applied to the end plate cannot be easily adjusted during assembly and may be either too high or too low. Description of the invention

[0003] The invention aims to remedy some of the drawbacks of the prior art.

[0004] According to a first aspect of the invention, a prismatic battery is proposed, in particular for powering an electric motor of an electric or hybrid vehicle, the prismatic battery comprising: • at least one stack of prismatic battery cells stacked along a prismatic battery reference axis, • a casing, which houses the prismatic battery cell stack, • at least one end plate located inside the housing and extending into a space between an end wall of the housing and an axial end of the prismatic battery cell stack and • at least one stress device comprising at least one movable stress element in contact with a contact face of the end plate opposite the prismatic battery cell stack, and at least one spring applying directly or indirectly a stress force to the stress element in the direction of the prismatic battery cell stack, such that the stress element applies a pressure force to the end plate with an axial pressure force component in the direction of the prismatic battery cell stack, the stress device being a stress unit removably fixed to the housing and provided with a frame that houses the spring and guides the stress element.

[0005] The excitation unit can be pre-assembled before being mounted in or on the prismatic battery housing. It can also be easily removed from the housing, for example for maintenance or recycling.

[0006] The potential and kinetic energy of the spring can be transmitted directly to the excitation member, for example if the spring is fixed to the excitation member or if the excitation member is provided with a spring seat on which one end of the spring rests.

[0007] It can also be transmitted by one or more intermediate elements, which transmit the force and motion of the spring to the moving actuating element with a transmission ratio that can be chosen to amplify the pressure force or the stroke of the actuating element. Various types of intermediate elements can be considered, including one or more of the following: • a spring seat integrated into or attached to the stressing element • a lever, which pivots around a pivot axis between the first final position and the second final position; • a cam, which rotates around a pivot axis perpendicular to the reference; • a beveled slider, which slides in a direction of translation perpendicular to the reference axis.

[0008] The spring force and the pressure force applied to the end plate are related to each other by a strictly increasing function, i.e., an increase in the spring force leads to an increase in the pressure force at least within the operating range. This function may be proportional or not depending on the presence and type of intermediate element.

[0009] Adjusting the actuation force allows for easy adjustment of the pressure force. In one embodiment, the actuation unit further includes an adjustment mechanism for adjusting the actuation force, the adjustment mechanism being at least partially housed within the frame. In one embodiment, the adjustment mechanism includes a non-reversible motion transformation mechanism, preferably bidirectional, and an adjustment interface allowing a user to actuate the non-reversible motion transformation mechanism, for example, to adjust, i.e., increase or decrease, the actuation force when the prismatic battery is installed in the vehicle or during a maintenance operation.

[0010] In a preferred embodiment, which minimizes the number of parts, the adjusting element and the stressing element are fixed to each other and the non-reversible transformation mechanism is such that it allows adjustment of the position of a spring seat to transfer force and motion between the spring and the stressing element relative to the stressing element.

[0011] In another embodiment, the adjustment element and the non-reversible transformation mechanism allow the position of a spring-loaded seat fixed to the frame to be adjusted.

[0012] In a preferred embodiment, the non-reversible motion transformation mechanism comprises a screw and nut mechanism. When the stressed element is in contact with the end plate, one of the screws and nuts is rotationally fixed relative to the housing, and another screw and nut are translationally fixed relative to the housing. A particularly simple stressing unit is obtained when the stressed element and the adjusting element are two regions of a single threaded rod or a single screw.

[0013] Other non-reversible motion transformation mechanisms can be used, such as a worm gear mechanism comprising a worm gear that meshes with a worm wheel.

[0014] In one embodiment, the adjustment mechanism is accessible from outside the housing. It is therefore possible to adjust the pressure force without having to open the housing.

[0015] In a preferred embodiment, the frame guides the movable stressing element in translation in a direction parallel to the reference direction. A movable stressing element, such as a rod, is particularly well-suited to a configuration in which the frame of the stressing unit is located outside the housing.

[0016] Various mechanical springs can be used, including helical springs, Belleville washers, leaf springs, or combinations thereof. In one embodiment, the spring is a contraction spring with an operating stroke of at least 5 mm, preferably 10 mm in the frame, between a fully contracted state and a relaxed or partially relaxed state. The contraction spring, for example, a helical spring or a set of Belleville washers, preferably has a contraction direction parallel to the reference axis.

[0017] In one embodiment, the frame of the excitation unit is located within the housing. This configuration may be preferred if it is necessary to protect the excitation unit from shocks or other interference before the prismatic battery is mounted in the vehicle. To allow adjustment of the excitation force from outside the housing, the housing may have a through hole through which the adjustment interface of the adjustment mechanism is accessible either from inside the housing or protrudes from the outside of the housing.

[0018] The spring can also be located outside the housing, which has a through hole through which the activating element protrudes into the housing. This configuration has the advantage of maximizing the volume available for the battery cells inside the housing, and therefore maximizing the power density of the prismatic battery.

[0019] According to another aspect of the invention, a prismatic battery is proposed, in particular for powering an electric motor of an electric or hybrid vehicle, the prismatic battery comprising: • at least one stack of prismatic battery cells stacked along a prismatic battery reference axis, • a casing, which houses the prismatic battery cell stack, • at least one end plate located inside the housing and extending in a space between an end wall of the casing and an axial end of the prismatic battery cell stack and • at least one stressing device comprising at least one movable stressing element in contact with a contact face of the end plate opposite the prismatic battery cell stack, and at least one spring applying directly or indirectly a stressing force to the stressing element towards the prismatic battery cell stack, such that the stressing element applies a pressure force to the end plate with an axial pressure force component towards the prismatic battery cell stack, the spring being located outside the housing, which has a through hole through which the stressing element protrudes into the housing.

[0020] This configuration has the advantage of maximizing the available volume for the battery cells inside the case, and therefore maximizing the power density of the prismatic battery, and allowing adjustment of the stress force without having to open the case.

[0021] According to another aspect of the invention, an electric or hybrid vehicle is provided comprising an electric drive motor and at least one prismatic battery according to one or more of the preceding aspects of the invention, to supply energy to the electric drive motor. Brief description of the drawings

[0022] Other advantages and features of the invention will become more apparent upon reading the following description of specific embodiments of the invention given by way of non-limiting examples and shown in the accompanying drawings in which: • The [Fig. 1] is a schematic view of an electric or hybrid vehicle equipped with a prismatic battery according to an embodiment of the invention; • Fig. 2 is an isometric view of a prismatic battery according to an embodiment of the invention; • [Fig.3] is an isometric cross-sectional view of a pair of stress units from the prismatic battery of [Fig.2]; • [Fig.4] is another isometric cross-sectional view of one of the pressure units of [Fig.3]; • [Fig.5] is a cross-sectional view of the stress unit of [Fig.4]; • [Fig.6] is an isometric view of the stress unit of [Fig.3], with a cap removed to show the interior space of a frame of the stress unit; • Fig. 7 is a schematic view of an electric or hybrid vehicle equipped with a prismatic battery according to another embodiment of the invention; • [Fig.8] is a schematic view of an electric or hybrid vehicle equipped with a prismatic battery according to another embodiment of the invention; • Figure 9 is a schematic view of an electric or hybrid vehicle equipped with a prismatic battery according to another embodiment of the invention. Figure 10 is a schematic view of an electric or hybrid vehicle equipped with a prismatic battery according to another embodiment of the invention.

[0023] The corresponding reference numbers refer to identical or corresponding parts in each of the figures. Description of the implementation methods

[0024] Fig. 1 schematically illustrates an electric or hybrid vehicle 10 equipped with an electric drive motor 12, powering traction wheels 14 via a mechanical transmission 16. The electric motor 12 is powered by one or more prismatic battery assemblies 20, each comprising at least one stack 22 of prismatic battery cells 24 stacked along a reference axis 100 of the prismatic battery assembly 20, housed in a casing 26.

[0025] One or more end plates 28 are located inside the housing 26 in a space between an end wall 30 of the housing and an axial end of each stack 22 of prismatic battery cells 24. The end plate(s) 28 are movable in translation parallel to the reference axis 100, at least in one direction of stress 200 towards the stack 22 of prismatic battery cells 24.

[0026] The prismatic battery 20 is provided with at least one pressure unit 32 to push the end plate(s) 28 towards the stack(s) 22 of battery cells 24 and maintain a pressure force throughout the life of the prismatic battery 20 in order to absorb the play that would otherwise accumulate between the battery cells 24 as their volume decreases over time.

[0027] In [Fig. 1], two stress units 32 are schematically illustrated, each with a movable stress element 34 in contact with a contact face 36 of the end plate 28 opposite the stack 22, at least one spring 38 applying a stress force directly or indirectly to the stress element 34 in the direction of the stack 22, such that the stress element 34 applies a pressure force to the end plate 28 with an axial component 36 in the direction of the stack 22 of prismatic battery cells 24. Each stress unit 32 is housed in a frame 40, which is removably attached to the housing 26, on the outside of the housing 26, by means of fasteners 42. An adjustment mechanism 44 comprising an adjustment interface 46 allows the stress force of the spring 38 to be adjusted.

[0028] In an embodiment shown in more detail in Figures 2 to 6, several end plates 28 may be provided, each of them being pushed by one or more load units 32 acting in parallel. More specifically, each load unit 32 is provided with a frame 40, which houses a nut 48 and a compression spring 38 compressed between the nut 48 and the frame 40. The frame 40 may be made in two parts, with a body 50 and a threaded cap 52 fixed to the body 50. Optionally, two parallel 32 stress units can share a common frame, as shown in Figures 3 to 6.

[0029] The movable stressing element 34 is a rod that passes through a hole 54 in the body 50 of the frame 40 and another hole 56 in the cap 52 at an opposite end of the frame 40, so that the rod 34 is guided in translation parallel to a translation axis 300 and free to rotate about the translation axis 300. The rod 34 has an intermediate threaded portion engaged in the nut 48 to provide a threaded connection 58. The nut 48 has a radial projection 60, which is engaged in a groove 62 in the body of the frame 50, parallel to the rod 34, so that the nut 48 is free in translation parallel to the rod 34 but cannot rotate about the translation axis 300 relative to the frame 40.

[0030] The frame 40 can be removably fixed to the end wall 30 of the housing 26 by means of removable fasteners 42, such as threaded fasteners, in a position in which the through holes 54, 56 of the frame 40 are aligned with a through hole 64 in the end wall 30 of the housing 26.

[0031] In this position, the rod 34 protrudes through the hole 64 in the housing 26 and comes into contact with the associated end plate 28 and the translation axis 300 of the rod 34 is parallel to the reference direction 100 of the housing, so that the rod 34 rests against the associated end plate 28. A free end of the rod 34 opposite the end plate 28 is provided with a user interface, here a hexagonal hole, which constitutes the adjustment interface 46.

[0032] With the rod 34 resting on the end plate 28, the threaded connection 58 between the rod 34 and the nut 48 constitutes a mechanism for transforming the non-reversible bidirectional mechanical motion. This mechanism allows a user to screw the rod 34, which rotates about its axis 300 without translational movement, thereby driving the nut 48 in a direction opposite to the direction of the applied force 200, so as to adjust the load on the compression spring 38 to a desired level. Thus, the screw and nut mechanism between the nut 48 and the rod 34 constitutes an adjustment mechanism 44 for adjusting the applied force on the compression spring 38.

[0033] Once loaded, the spring 38 rests on the nut 48, which acts as a spring seat fixed to the rod 34, and pushes the nut 48, thereby transferring a pressure force to the rod 34. The rod 34 acts as a pressure element and applies a pressure force to the end plate 28, which is approximately equal to the pressure force applied by the spring, excluding friction. The translation of the nut 48 within the frame 40 is limited in one direction by the maximum contraction of the spring 38 and in the opposite direction by the cap 50, which acts as a stop. The stroke of the spring 38 is preferably sufficient so that it remains in contact with the nut 48 when the latter rests on the cap 50. The force applied by the spring 38 to the nut 48 and the rod 34 decreases when the rod 34 moves in the direction of stress 200, but it is adjusted so that the axial pressure force applied to the end plate 28 at the end of the service life of the prismatic stack assembly 20 is sufficient when the maximum expected decrease in the volume of the prismatic stack elements 24 has occurred.

[0034] The stress unit 32 of the embodiment shown in Figures 2 to 6 has the advantage of combining a number of functions in a small number of parts and in a very compact arrangement, in particular • the function of storing potential mechanical energy thanks to spring 38, • the function of transferring this energy to the end plate 28 via the threaded connection 58 between the rod 34 and the nut 48, • the function of adjusting the applied force via the adjustment interface 46 of the rod 34, the threaded connection 58 between the rod and the nut, and the sliding connection 60, 62 between the nut 48 and the frame 40, and • the function of holding the parts of the stress unit 32 together in a detachable unit of the envelope 26, by means of the frame 40 and the fasteners 42.

[0035] The prismatic accumulator schematically illustrated in [Fig. 7] differs from the prismatic accumulator of the embodiment shown in Figures 2 to 6 in that the load of the spring 38 is applied to a cam 148, which rotates about an axis perpendicular to the reference direction and pushes a squeezing element 34, in this case a squeezing rod, in a translational direction parallel to the reference axis 100. The squeezing force of the spring 38 can be adjusted by means of a non-reversible adjustment mechanism 144, which includes a lever 146 and a ratchet wheel 158. In this embodiment, the adjustment interface is materialized by the lever 146, which is a separate part of the squeezing element 34.Furthermore, the movement of the spring 38 is not transmitted 1:1 to the stress element 34, which means that the shape of the cam 148 can be optimized to provide a desired transmission ratio between the spring 38 and the stress element 34.

[0036] The prismatic battery of [Fig.8] differs from previous embodiments in that the load of the spring 38 is applied to a beveled slider 248, which slides in a direction perpendicular to the reference axis, and pushes a stress element, in this case a stress rod 34 fixed to another beveled slider 234, in a translational direction 300 parallel to the reference axis 100. The stress force of the spring 38 can be adjusted by means of a non-reversible adjustment mechanism 244, which includes a screw 258 and a nut 248.2.

[0037] The prismatic battery pack of [Fig.9] differs from previous embodiments in that the actuation unit 32 is located inside the housing 26 of the prismatic battery pack 10, with the exception of the adjustment element 46, which protrudes from the housing 26 to remain accessible from outside the housing 26. Although the actuation member 34 is shown in the form of a rod, it could also be a cam similar to the cam 148 of [Fig.7], or a slider similar to the slider 234 of [Fig.8].

[0038] The prismatic battery of [Fig. 10] differs from previous embodiments in that the excitation unit 32 is pre-charged and is not equipped with an adjustment mechanism.

Claims

1.

2. Demands Prismatic battery (20), in particular for powering an electric drive motor (12) of an electric or hybrid vehicle (10), the prismatic battery (20) comprising: - at least one stack (22) of prismatic battery cells (24) stacked along a reference axis (100) of the prismatic battery (20), - a casing (26), which houses the stack (22) of prismatic battery cells (24), - at least one end plate (28) located inside the housing (26) and extending into a space between an end wall (30) of the housing and an axial end of the stack (22) of prismatic battery cells (24) and - at least one stressing device comprising at least one movable stressing element (34) in contact with a contact face of the end plate (28) opposite the stack (22) of prismatic battery cells (24), and at least one spring (38) applying directly or indirectly a stressing force to the stressing element in the direction of the stack (22) of prismatic battery cells (24), such that the stressing element (34) applies a pressure force to the end plate (28) with an axial pressure force component (36) in the direction of the stack (22) of prismatic battery cells (24), characterized by the fact that the stressing device is a stressing unit (32) removably fixed to the housing (26) and provided with a frame (40) which houses the spring (38) and guides the stressing element (34). Prismatic battery (20) according to claim 1, further comprising at least one intermediate element (48, 148, 248) between the spring (38) and the movable stress element (34), for transmitting the force and movement of the spring (38) to the movable stress element (34).

3. Prismatic battery (20) according to claim 4, wherein the intermediate element (48, 148, 248) comprises at least one of the following: - a spring seat (48) integrated or fixed to the excitation element (34) - a lever, which pivots about a pivot axis between the first final position and the second final position; - a cam (148), which rotates about a pivot axis perpendicular to the reference; - a beveled slider (248), which slides in a translational direction perpendicular to the reference axis.

4. Prismatic battery (20) according to any one of the preceding claims, wherein the stress unit (32) further comprises an adjustment mechanism (44) for adjusting the stress force, the adjustment mechanism (44) being at least partially housed in the frame (40).

5. Prismatic battery (20) according to claim 4, wherein the adjustment mechanism (44) comprises a non-reversible motion transformation mechanism, preferably bidirectional (58) and an adjustment interface (44) enabling a user to actuate the non-reversible motion transformation mechanism (58).

6. Prismatic battery (20) according to claim 4 or claim 5, wherein the adjusting element (44) and the stressing element (34) are fixed together and the non-reversible transformation mechanism (58) is such that it allows adjustment of a position of a spring seat (48) to transfer force and motion between the spring (48) and the stressing element (34) relative to the stressing element (34).

7. Prismatic battery according to any one of claims 4 to 6, wherein the adjustment mechanism is accessible from outside the housing.

8. Prismatic battery (20) according to any one of the preceding claims, wherein the frame (40) guides the movable stressing element (34) in translation in a translation direction (300) parallel to the reference direction (100).

9. Prismatic battery according to any one of the preceding claims, wherein the spring (38) is a contraction spring with an operational stroke of at least 5 mm, preferably 10 mm in the frame (40), between a fully contracted state and a relaxed or partially relaxed state.

10. Prismatic battery according to claim 9, wherein the spring (38) has a contraction direction parallel to the reference axis.

11. Prismatic battery according to any one of claims 1 to 7, wherein the frame (40) of the stress unit (32) is located in the housing (26).

12. Prismatic battery according to the preamble of claim 1 or according to any of the preceding claims, characterized in that the spring (38) is located outside the housing (26), which has a hole (64) through which the stressing element (34) protrudes inside the housing (26).

13. Electric or hybrid motor vehicle (10) comprising an electric drive motor (12) and at least one prismatic battery (20) according to any one of the preceding claims, for powering the electric drive motor (12).