Surface pressure application mechanism

Abstract

To provide a surface pressure application mechanism which can be miniaturized.SOLUTION: A surface pressure application mechanism for applying a surface pressure to a stack of a battery in a stacking direction includes: first and second support parts which are located in the stacking direction relative to the stacked support the stack; a holding part for holding the first and second support parts; and a spring and a hydraulic chamber which are located between the first and second support parts and connect the first and second support parts. The first and second support parts are rotatably male-female coupled with the holding part around the stacking direction as a rotation axis, and when one of the support parts is held by the holding part in a stationary state, the first and second support parts are movable in the stacking direction by the rotation of the other support part around the rotation axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface pressure applying mechanism. [Background technology]

[0002] A load-applying device is known that is configured to apply a restraint load to the energy storage module using a predetermined number of elastic bodies in a first form, and to apply a restraint load to the energy storage module using more than the predetermined number of elastic bodies in a second form, and to switch from the first form to the second form depending on deterioration due to aging, etc. (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-114625 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the device described in Patent Document 1, in order to apply an appropriate load to the all-solid-state battery over a long period of time, it is necessary to provide another elastic body in the device that is not used before the elastic body deteriorates but is used after the elastic body deteriorates, which causes a problem that the entire device becomes large.

[0005] The problem to be solved by the present invention is to provide a surface pressure applying mechanism that can be made compact. [Means for solving the problem]

[0006] The present invention solves the above problem by providing a surface pressure applying mechanism that applies surface pressure to a battery stack in the stacking direction, and includes first and second support parts that are positioned relative to the stack in the stacking direction and support the stack, a holding part for holding the first and second support parts, and a spring and hydraulic chamber that are positioned between the first and second support parts and connect the first and second support parts, the first and second support parts being male-female coupled to the holding part so as to be rotatable around the stacking direction as an axis of rotation, and when either support part is held by the holding part in a stationary state, the other support part can rotate around the axis of rotation and move in the stacking direction. [Effects of the Invention]

[0007] According to the present invention, the surface pressure applying mechanism can be made smaller. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows a battery module including a surface pressure applying mechanism according to an embodiment of the present invention. [Figure 2] FIG. 2 is a top view and a partial cross-sectional view showing an example of a surface pressure applying mechanism according to this embodiment. [Figure 3] FIG. 3 is a schematic diagram for explaining an example of the movement operation of the second support part in the surface pressure applying mechanism according to the present embodiment. [Figure 4] FIG. 4 is a schematic diagram for explaining an example of the movement operation of the first support part in the surface pressure applying mechanism according to the present embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an example of the state of the first support portion and the second support portion when the surface pressure applying mechanism according to this embodiment is lowered. [Figure 6] FIG. 6 is a schematic diagram showing an example of the state of the first support portion and the second support portion when held in a stationary state in the surface pressure applying mechanism according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A surface pressure applying mechanism according to an embodiment of the present invention will be described with reference to the drawings. The surface pressure applying mechanism according to this embodiment is provided in a battery module of a lithium deposition-type all-solid-state battery. The battery module is mounted as a battery in a vehicle such as an electric vehicle. Note that the battery is not limited to an all-solid-state battery, and may be other secondary batteries or the like, as long as it expands and contracts.

[0010] FIG. 1 is a cross-sectional view schematically showing a battery module including a surface pressure applying mechanism according to an embodiment of the present invention. As shown in FIG. 1, the battery module 1 includes a stack 10 formed by stacking a plurality of all-solid-state batteries, a surface pressure applying mechanism 20, and a module case 30. In FIG. 1, the X-axis is the stacking direction in which the all-solid-state batteries are stacked. The Y-axis is the surface direction of the all-solid-state batteries, and is perpendicular to the X-axis. The battery module 1 is not limited to one, and multiple battery modules 1 may be provided.

[0011] The thickness of the laminate 10 in the stacking direction changes as it expands and contracts due to charging and discharging. The all-solid-state battery is not particularly limited, but for example, it is configured by stacking a negative electrode layer, a negative electrode current collector foil, a solid electrolyte layer, a positive electrode layer, and a positive electrode current collector foil in the stacking direction (X-axis direction). The stacking direction (X-axis direction) is the expansion and contraction direction of the battery.

[0012] The negative electrode layer is an alkali metal layer mainly composed of alkali metal that is released from the positive electrode layer, reaches the negative electrode current collector foil through the solid electrolyte layer, and deposits thereon as the all-solid-state battery is charged. The negative electrode layer is a layer that deposits on the negative electrode current collector foil during charging of the all-solid-state battery, increasing in volume and decreasing in volume during discharge. The negative electrode layer is, for example, a lithium metal layer. The negative electrode layer may include a layer other than the lithium metal layer, for example, an auxiliary layer that assists the deposition of the lithium metal layer. The negative electrode current collector foil is a foil-like member having electrical conductivity. The negative electrode current collector foil is, for example, a metal foil, and an example of this metal foil is copper foil. The negative electrode current collector foil may be made of an electrically conductive resin. The negative electrode current collector foil is joined to a negative electrode tab (not shown).

[0013] The solid electrolyte layer may be, for example, a sulfide solid electrolyte or an oxide solid electrolyte, with a sulfide solid electrolyte being preferred. The positive electrode layer contains at least a positive electrode active material capable of absorbing and releasing lithium (Li). While not particularly limited, it preferably contains a sulfur-containing positive electrode active material. The sulfur-containing positive electrode active material may be any material capable of absorbing and releasing lithium ions during charging and utilizing the sulfur oxidation-reduction reaction during discharging. The type of sulfur-containing positive electrode active material is not particularly limited, but particles or thin films of elemental sulfur (S), organic sulfur compounds, or inorganic sulfur compounds may be used. The positive electrode current collector foil is a conductive foil-like member. The positive electrode current collector foil is, for example, a metal foil, such as copper foil. The positive electrode current collector foil may be made of a conductive resin. The positive electrode current collector foil is bonded to a positive electrode tab (not shown).

[0014] The surface pressure applying mechanism 20 applies a compressive load to the laminate 10 in the stacking direction (X-axis direction) to apply a surface pressure. Specifically, the surface pressure applying mechanism 20 functions to maintain a surface pressure equal to or greater than a predetermined value in accordance with the expansion and contraction of the laminate 10. The surface pressure applying mechanism 20 includes a first support portion 21, a second support portion 22, a holding portion 23, and a connecting portion 24. The first support portion 21 and the second support portion 22 are positioned relative to the laminate 10 in the stacking direction to support the laminate 10. That is, in the surface pressure applying mechanism 20, the first support portion 21 and / or the second support portion 22 receive a load applied in the stacking direction due to the expansion and contraction of the laminate 10 and maintain the surface pressure applied to the laminate 10. Details of each component constituting the surface pressure applying mechanism 20 will be described later. Note that in this embodiment, the direction in which the first support portion 21 and the second support portion 22 are positioned relative to the laminate 10 in the stacking direction (X-axis direction) is defined as downward, and the direction opposite to downward relative to the laminate 10 is defined as upward. That is, the +X axis direction is upward, and the −X axis direction is downward.

[0015] The module case 30 is a cylindrical member with a bottom, and houses the stack 10 and the surface pressure applying mechanism 20 inside. The top and bottom surfaces of the module case 30 are circular when viewed from the stacking direction. The stack 10 is compressed and stored inside the module case 30 by the surface pressure applying mechanism 20. The module case 30 is not particularly limited, but for example, a metal case can be used. The module case 30 has an upper surface 31 and a lower surface 32 that face each other in the stacking direction, and surfaces extending from the sides of the upper surface 31 in a direction (X-axis direction) approximately perpendicular to the upper surface 31 are defined as side surfaces 33 that constitute the module case 30.

[0016] The laminate 10 has an upper surface 11 and a lower surface 12 located opposite the upper surface 11. The laminate 10 is housed so that the upper surface 11 contacts the upper surface 31 inside the module case 30. Inside the module case 30, a first support portion 21, a second support portion 22, and a connecting portion 24 are housed on the side of the lower surface 12 of the laminate 10. That is, when viewed from the stacking direction, the first support portion 21, the second support portion 22, and the connecting portion 24 overlap with the laminate 10 in the planar direction. The first support portion 21, the second support portion 22, and the connecting portion 24 are arranged side by side in the stacking direction (X-axis direction) in the order of first support portion 21, connecting portion 24, and second support portion 22. The connecting portion 24 is located between the first support portion 21 and the second support portion 22 and connects the first support portion 21 and the second support portion 22. The first support portion 21 has an upper surface 211 facing the lower surface 12 of the laminate 10. A compression spring 13 extending in the stacking direction (X-axis direction) may be disposed between the first support portion 21 and the laminate 10. The second support portion 22 has a lower surface 222 facing the lower surface 32 of the module case 30. The connecting portion 24 includes a spring 24a and a hydraulic chamber 24b.

[0017] Next, the surface pressure applying mechanism 20 will be described in detail. The first support portion 21 and the second support portion 22 are male-female coupled to the holding portion 23 so as to be rotatable around the stacking direction (X-axis direction) as a rotation axis. When the laminate 10 expands and contracts, if one of the support portions is held stationary by the holding portion 23, the other support portion can rotate around the rotation axis, thereby moving in the stacking direction. The stationary state refers to a state in which the support portions are stationary. In the stationary state, the support portions are held in the same position. A rotating support portion is also referred to as a support portion in a rotating state. The holding portion 23 is a member for holding the first support portion 21 and the second support portion 22. The holding portion 23 is a hollow cylindrical member and is arranged so as to contact the inner side surface 33 of the module case 30. The laminate 10, the first support portion 21, the second support portion 22, and the connecting portion 24 are arranged inside the holding portion 23. The first support portion 21 and the second support portion 22 are held at predetermined positions in the stacking direction by the holding portion 23. Furthermore, the first support portion 21 and the second support portion 22 can move in position along the inner side surface of the holding portion 23 in a rotating state within the space within the holding portion 23.

[0018] The first support portion 21 and the second support portion 22 can change their positions in the stacking direction by rotating and can receive the load applied from the laminated body 10 at any position by maintaining their positions in a stationary state. In this embodiment, the first support portion 21 and the second support portion 22 change the positions at which they receive the load applied from the laminated body 10, thereby adjusting the surface pressure applied to the laminated body 10. For example, when the laminated body 10 is expanding, the positions of the first support portion 21 and / or the second support portion 22 move downward, thereby preventing the surface pressure of the laminated body 10 from becoming excessive. Furthermore, when the laminated body 10 is contracting, the positions of the first support portion 21 and / or the second support portion 22 move upward, thereby preventing the surface pressure of the laminated body 10 from becoming too small.

[0019] The first support member 21 and / or the second support member 22 can be switched between a rotating state and a stationary state. Here, the state switching operation of the first support member 21 and the second support member 22 will be described using FIG. 2 . FIG. 2 is a top view and a partial cross-sectional view showing an example of a surface pressure applying mechanism according to this embodiment. In FIG. 2 , the Y axis and Z axis are directions along the top surfaces of the first support member and the second support member. The Z axis is perpendicular to the Y axis in the YZ plane. The X axis is perpendicular to the YZ plane. The XY axis display in FIG. 2 corresponds to the XY axis display in FIG. 1 . The upper view in FIG. 2 is a top view. The lower view in FIG. 2 is a cross-sectional view of the surface pressure applying mechanism taken along line AA′ in the upper view. FIG. 2 shows a portion of the surface pressure applying mechanism 20 of the battery module 1 shown in FIG. 1 . Although the stack 10 is not shown in the example of FIG. 2 , a load P1 of the stack 10 is applied from above the first support member 21 along the stacking direction (X-axis direction). Below, the configuration and operation of the support parts will be explained using the first support part 21 as an example, but since the second support part 22 has a similar configuration to the first support part 21 and operates in the same manner as the first support part 21, the explanation of the second support part 22 will be omitted and the explanation of the first support part 21 will be used as appropriate.

[0020] The first support portion 21 is a member including a main body portion 21a and a male screw portion 21b. The main body portion 21a is a disk-shaped member and, as shown in the top view, is circular when viewed from the stacking direction. The first support portion 21 rotates around a rotation axis passing through the center point of the circle. The main body portion 21a has an upper surface 211 and a lower surface 212 located opposite the upper surface 211, and a surface extending from a side of the upper surface 211 in a direction (X-axis direction) substantially perpendicular to the upper surface 211 is defined as a side surface portion 213 constituting the first support portion 21. The side surface portion 213 is disposed so as to face the holding portion 23. The upper surface 211 and the lower surface 212 are disposed so as to be perpendicular to the X-axis direction (stacking direction).

[0021] The male thread portion 21b is provided so as to protrude from the side surface portion 213. In other words, the male thread portion 21b is formed on the surface of the side surface portion 213. The male thread portion 21b includes a screw thread formed in a spiral shape along the circumferential direction of the side surface portion 213. The number of screw threads constituting the male thread portion 21b may be one, or may be two or more. The first support portion 21 is held by the holding portion 23 when the male thread portion 21b engages with a female thread portion 23a provided on the holding portion 23. The female thread portion 23a is formed on the inner side surface portion 231 of the holding portion 23. The female thread portion 23a includes a plurality of screw threads formed in a spiral shape along the circumferential direction of the surface of the inner side surface portion 231.

[0022] The male screw portion 21b slidably engages with the female screw portion 23a. When the first support portion 21 rotates, the male screw portion 21b slides along the female screw portion 23a. The first support portion 21 moves in the stacking direction by rotating around the rotation axis with the male screw portion 21b engaged with the female screw portion 23a. For example, the first support portion 21 moves downward (in the -X-axis direction) by rotating right around the rotation axis (X-axis), and moves upward (in the +X-axis direction) by rotating left around the rotation axis (X-axis).

[0023] In this embodiment, the friction force acting on the male thread portion 21b of the first support portion 21 when it moves in the contraction direction (upward) of the laminate 10 is smaller than the friction force acting on the male thread portion 21b when it moves in the expansion direction (downward) of the laminate 10. For example, the friction coefficient of the sliding surface of the male thread portion 21b in contact with the female thread portion 23a when the first support portion 21 moves in the contraction direction is smaller than the friction coefficient of the sliding surface of the male thread portion 21b in contact with the female thread portion 23a when it moves in the expansion direction.

[0024] In the example of FIG. 2, the male thread portion 21b is formed to protrude in a triangular shape in a cross-sectional view and has an upper inclined portion 211b and a lower inclined portion 212b. The upper inclined portion 211b and the lower inclined portion 212b are sliding surfaces that come into contact with the surface of the female thread portion 23a. The coefficient of friction on the surface of the upper inclined portion 211b is smaller than the coefficient of friction on the surface of the lower inclined portion 212b. For example, the upper inclined portion 211b has a ball screw structure in which balls are provided rollably on the surface of the upper inclined portion 211b. By interposing a ball between the upper inclined portion 211b and the surface of the female thread portion 23a, when the male thread portion 21b slides along the female thread portion 23a, the coefficient of friction of the upper inclined portion 211b is smaller than the coefficient of friction when no ball is interposed. On the other hand, no ball is interposed between the lower inclined portion 212b and the surface of the female thread portion 23a. For example, the lower inclined portion 212b is a trapezoidal thread inclined portion. As a result, the coefficient of friction on the surface of the upper inclined portion 211b is smaller than the coefficient of friction on the surface of the lower inclined portion 212b. When the first support portion 21 moves upward while rotating, the surface of the upper inclined portion 211b applies upward pressure to the surface of the female thread portion 23a. At this time, because the coefficient of friction on the surface of the upper inclined portion 211b is smaller than the coefficient of friction on the surface of the lower inclined portion 212b, the friction force acting on the male thread portion 21b is smaller than the friction force acting on the male thread portion 21b when moving downward.

[0025] When each support part supports the stack 10, its rotation is suppressed by a high coefficient of friction, so each support part self-locks and movement in the stacking direction is restricted. On the other hand, when the support part moves, the friction involved in the movement can be reduced by increasing the hydraulic pressure to release the self-lock.

[0026] By reducing the coefficient of friction on the surface of the upper inclined portion 211b, the support portion can be moved upward rapidly. As a result, the amount by which the support portion rises is greater than the amount by which the support portion falls when it moves downward, allowing the support portion to move upward more reliably. Since a large driving force is required to drive the support portion against the load applied by the stack 10 when it rises, reducing the coefficient of friction when it rises reduces the operating energy, and the small coefficient of friction when it is held enables it to be held with little energy.

[0027] The first support portion 21 and the second support portion 22 support the laminate 10 in a stationary state and apply a surface pressure to the laminate 10 in response to expansion and contraction of the laminate 10. For example, when the first support portion 21 is stationary, the first support portion 21 applies a surface pressure to the laminate 10. When the first support portion 21 is rotating, a load applied from the laminate 10 is applied to the second support portion 22 via the first support portion 21. As shown in the example of FIG. 2, when a load P1 is applied to the first support portion 21 and the second support portion 22, pressure is applied to the surface of the female screw portion 23a via the surface of the lower inclined portion 212b. In this way, the first support portion 21 and the second support portion can maintain their positions in the stacking direction and maintain the surface pressure of the laminate because the male screw portion 21b is engaged with the female screw portion 23a.

[0028] The surface pressure applying mechanism 20 also includes a connecting portion 24 between the first support portion 21 and the second support portion 22. The connecting portion 24 includes a spring 24a and a hydraulic chamber 24b. The spring 24a is a tension spring located within the hydraulic chamber 24b and extending in the stacking direction, connecting the first support portion 21 and the second support portion 22. The spring 24a biases the first support portion 21 and the second support portion 22 toward each other, as indicated by arrow D2. The hydraulic chamber 24b is a hollow, tubular member, and both ends are sealed by the lower surface 212 of the first support portion 21 and the upper surface 221 of the second support portion 22, respectively. The hydraulic chamber 24b is surrounded by the lower surface 212 of the first support portion 21, the upper surface 221 of the second support portion 22, and the inner side surface portion 231 of the holding portion 23. The hydraulic chamber 24b is a so-called cylinder. The first support portion 21 and the second support portion 22 are arranged to be slidable along the inner side surface of the hydraulic chamber 24b when in a rotating state. The first support portion 21 and the second support portion 22 are so-called pistons. The hydraulic chamber 24b is filled with oil, and the hydraulic pressure is adjusted by supplying and discharging the oil. For example, the hydraulic chamber 24b adjusts the internal hydraulic pressure by supplying and discharging oil through an opening provided in the inner side surface portion 231 of the holding portion 23. The hydraulic chamber 24b increases the internal hydraulic pressure by supplying oil, thereby biasing the first support portion 21 and the second support portion 22 away from each other, as indicated by arrow D3. When the hydraulic chamber 24b reduces the internal hydraulic pressure by discharging the oil, the pressure that moves the first support portion 21 and the second support portion 22 away from each other is weakened, and the tensile force by the spring 24a that moves the first support portion 21 and the second support portion 22 toward each other is strengthened. In this embodiment, by adjusting the hydraulic pressure in the hydraulic chamber 24b, the first support portion 21 or the second support portion 22 in a rotating state moves in the stacking direction due to the hydraulic pressure or the bias of the spring. Specifically, when one of the first support portion 21 and the second support portion is stationary and the other support portion is rotating, the greater the hydraulic pressure in the hydraulic chamber 24b, the more the hydraulic pressure in the hydraulic chamber 24b moves the other support portion in a rotating state in the stacking direction so as to move away from the one support portion in a stationary state. Furthermore, the smaller the hydraulic pressure in the hydraulic chamber 24b, the more the spring 24a moves the other support portion in a rotating state in the stacking direction so as to move closer to the one support portion in a stationary state.

[0029] In this embodiment, the first support portion 21 may include an abutment portion 21e on the lower surface 212 of the first support portion 21. The lower surface 212 of the first support portion 21 faces the upper surface 221 of the second support portion 22. The lower surface 212 of the first support portion 21 and the upper surface 221 of the second support portion 22 are examples of the "main surface of the first support portion" and the "main surface of the second support portion" described in the claims. The lower surface 212 of the first support portion 21 has a first joint portion 212a that joins with one end of the spring 24a. The upper surface 221 of the second support portion 22 has a second joint portion 221a that joins with the other end of the spring 24a. The abutment portion 21e is located on a portion of the lower surface 212 of the first support portion 21 other than the first joint portion 212a. The lower surface 212 of the first support portion 21 and the upper surface 221 of the second support portion 22 are urged toward each other by the spring 24a as the hydraulic pressure in the hydraulic chamber 24b decreases. The abutting portion 21e is a portion where the lower surface 212 of the first support portion 21 and the upper surface 221 of the second support portion 22 abut against each other when the first support portion 21 and the second support portion 22 are brought closer by the spring 24a. The abutting portion 21e is formed to protrude from the lower surface 212 of the first support portion 21. When the lower surface 212 of the first support portion 21 and the upper surface 221 of the second support portion 22 abut against each other at the abutting portion 21e, the first joint portion 212a and the second joint portion 221a are spaced apart by a predetermined length or more. The predetermined length is the minimum length of the spring 24a (the length at maximum compression). The abutting portion 21e may also be provided on the upper surface 221 of the second support portion 22. In this case as well, the abutting portion 21e is provided on a portion other than the second joint portion 221a on the upper surface 221 of the second support portion 22. The abutting portion 21e may be provided on either one of the first support portion 21 and the second support portion 22, or on both.

[0030] In this embodiment, the rotational movement of the first support portion 21 and the second support portion 22 and the adjustment of the hydraulic pressure in the hydraulic chamber of the connecting portion 24 may be controlled by a controller (not shown). The controller is configured with a memory such as a ROM or a RAM, and a processor such as a CPU. The controller acquires the state of the stacked body 10 and controls the rotational movement of each support portion and the hydraulic pressure in the hydraulic chamber of the connecting portion 24 according to the state of the stacked body 10. The state of the stacked body 10 includes, for example, an expansion / contraction state or a surface pressure state of the stacked body 10. The first support portion 21, the second support portion 22, and the connecting portion 24 are controlled by commands from the controller. The controller may collectively control the first support portion 21, the second support portion 22, and the connecting portion 24, or may be provided for each of the first support portion 21, the second support portion 22, and the connecting portion 24. The first support part 21 and the second support part 22 are rotated, for example, by a resultant force in the vertical direction of the hydraulic pressure of the hydraulic chamber 24b and the tensile force of the spring 24a. Alternatively, a hydraulic motor and a reducer may be built into the first support part 21 and the second support part, and the first support part 21 and the second support part 22 may be rotated by rotating the hydraulic motor with the hydraulic pressure of the hydraulic chamber 24b.

[0031] In this embodiment, by switching between a stationary state and a rotating state of the first support unit 21 and the second support unit, it is possible to maintain the surface pressure of the laminate 10 with one support unit while changing the position of the other support unit while reducing the burden on the other support unit, thereby increasing the durability of the surface pressure applying mechanism and making it possible to appropriately maintain the surface pressure of the laminate 10 over a long period of time. Furthermore, even when the thickness of the laminate 10 varies greatly in the stacking direction, it is possible to accommodate changes in the thickness of the laminate 10 by changing the positions of the support units. Therefore, there is no need to increase the size of the surface pressure applying mechanism to accommodate the maximum change in thickness of the laminate 10, and the surface pressure applying mechanism can be made smaller and the drive energy can be reduced.

[0032] Here, the movement of each support unit in a rotating state will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic diagram illustrating an example of the movement of the second support unit in the surface pressure applying mechanism according to this embodiment. FIG. 4 is a schematic diagram illustrating an example of the movement of the first support unit in the surface pressure applying mechanism according to this embodiment. FIGS. 3 and 4 are schematic diagrams of the surface pressure applying mechanism shown in FIG. 2. Note that in FIGS. 3 and 4, for the sake of simplicity, the male and female threads are not depicted as being spirally formed, but they are actually spirally formed as shown in FIG. 2. Therefore, each support unit moves vertically upon rotation. Also, although the stack 10 is not shown in FIGS. 3 and 4, a load P1 of the stack 10 is applied from above to the first support unit 21. In FIG. 3, the first support unit 21 is held by the holder 23 in a stationary state and supports the stack 10. In FIG. 4, the second support portion 22 is held by the holding portion 23 in a stationary state and supports the stack 10.

[0033] First, referring to FIG. 3, the movement of the second support portion 22 in the rotating state will be described. In FIG. 3, the state of the second support portion 22 transitions in the order of states (a), (b), and (c). While the state of the second support portion 22 transitions from (a) to (c), the first support portion 21 is held stationary and receives a load P1 applied from the stack 10. In state (a), the second support portion 22 is held stationary by the holder 23. At this time, the load P1 of the stack 10 is applied to the holder 23 via the lower inclined portions 212b at both ends of the first support portion 21 and the second support portion 22. In other words, both the first support portion 21 and the second support portion 22 support the stack 10. For example, in state (a), the load of the stack 10 is balanced with the resultant force of the hydraulic force of the hydraulic chamber 24b and the tensile force of the spring 24a, causing the first support portion 21 to be stationary. Suppose that the surface pressure applied to the laminate 10 becomes too small due to shrinkage of the laminate 10. At this time, in order to adjust the surface pressure of the laminate 10 to increase, the position of the second support portion 22 in the stacking direction moves upward.

[0034] First, in state (b), the second support part 22 is pulled upward by the spring 24a as the hydraulic pressure in the hydraulic chamber 24b decreases, causing the second support part 22 to enter a rotating state. At this time, upward pressure is applied to the surface of the female thread part 23a via the surface of the upper inclined part 211b of the male thread part 21b of the second support part 22. From state (b), the second support part 22 moves its position in the stacking direction upward while rotating due to the tensile force of the spring 24a.

[0035] In state (c), the second support portion 22 has moved upward to a position where the first support portion 21 and the second support portion 22 abut at the abutment portion 21e. When the second support portion 22 abuts against the first support portion 21, its rotation stops and it returns to a stationary state. The second support portion 22 is again held in a stationary state by the holding portion 23. In state (c), both the first support portion 21 and the second support portion 22 support the stack 10.

[0036] Next, the movement of the first support portion 21 in the rotating state will be described using FIG. 4. In FIG. 4, the state of the first support portion 21 transitions in the order of (a), (b), and (c). While the state of the second support portion 22 transitions from (a) to (c), the second support portion 22 receives a load P1 applied from the stacked body 10 while remaining stationary. State (a) in FIG. 4 is the same state as state (c) in FIG. 3. The first support portion 21 and the second support portion 22 are stationary in abutment. Both the first support portion 21 and the second support portion 22 support the stacked body 10 while remaining stationary. In FIG. 4, an example will be described in which the first support portion 21 moves upward in the stacking direction after the second support portion 22 moves upward in the stacking direction in the example of FIG. 3.

[0037] First, in state (b), the first support part 21 receives hydraulic pressure from below as the hydraulic pressure in the hydraulic chamber 24b increases, causing it to rotate. At this time, upward pressure is applied to the surface of the female thread part 23a via the surface of the upper inclined part 211b of the male thread part 21b of the first support part 21. From state (b), the first support part 21 moves its position in the stacking direction upward while rotating due to the hydraulic pressure in the hydraulic chamber 24b.

[0038] In state (c), the position of the first support part 21 moves upward in the stacking direction, and the load of the stack 10 balances with the resultant force of the hydraulic force of the hydraulic chamber 24b and the tensile force of the spring 24a, causing the first support part 21 to become stationary. As described above, the positions at which the first support part 21 and the second support part 22 are held by the holding part 23 move.

[0039] In this embodiment, the positions of the first support portion 21 and the second support portion 22 in the stacking direction can be changed by alternately performing a moving operation in which one support portion is stationary and the other support portion is rotated and moved in the stacking direction on the first support portion 21 and the second support portion 22. Also, as shown in FIGS. 3 and 4, the surface pressure applying mechanism 20 can switch from a state in which the first support portion 21 is stationary and supporting the stacked body 10 (FIG. 3) to a state in which the second support portion 22 is stationary and supporting the stacked body 10 (FIG. 4). Conversely, the surface pressure applying mechanism 20 can switch from a state in which the second support portion 22 is stationary and supporting the stacked body 10 (FIG. 4) to a state in which the first support portion 21 is stationary and supporting the stacked body 10 (FIG. 3). In a step in which the second support rotates while the first support 21 supports the stacked body 10 in a stationary state, thereby moving the stacked body 10 in the stacking direction, or in a step in which the first support 21 rotates while the second support 22 supports the stacked body 10 in a stationary state, thereby moving the stacked body 10 in the stacking direction, one of the support members in the rotating state can move its position in the stacking direction, thereby changing the distance between the first support 21 and the second support 22. For example, in the example of FIG. 3, the distance between the first support 21 and the second support 22 in state (b) is greater than the distance between the first support 21 and the second support 22 in state (c). Also, in the example of FIG. 4, the distance between the first support 21 and the second support 22 in state (b) is smaller than the distance between the first support 21 and the second support 22 in state (c). As described above, by changing the distance between the first support portion 21 and the second support portion 22, the position of one support portion can be changed while the other support portion supports the stack 10, thereby making it possible to change the position at which the stack 10 is supported.

[0040] Furthermore, the stroke amount (movement amount) by which one support part in the rotating state moves in the stacking direction is smaller than the maximum stroke amount by which one support part in the rotating state can move in the stacking direction. In this embodiment, if the series of moving operations shown in FIGS. 3 and 4 are considered to be one process, the support part in the rotating state moves between adjacent thread grooves among the multiple thread grooves of the female screw part 23a in one process. That is, the stroke amount of the support part in one process is the distance between adjacent thread grooves of the female screw part 23a. Furthermore, for example, if the female screw part 23a has two or more threads as shown in FIGS. 3 and 4, one process can be repeated multiple times, and therefore the maximum stroke amount of the support part (arrow Sm in FIG. 4) becomes larger than the stroke amount of the support part in one process (arrow S in FIGS. 3 and 4).

[0041] Furthermore, the direction in which the first support portion 21 moves when the second support portion 22 is stationary and supporting the stacked body 10 is the same as the direction in which the second support portion 22 moves when the first support portion 21 is stationary and supporting the stacked body 10. For example, as shown in FIGS. 3 and 4, when the second support portion 22 moves upward, the first support portion 21 also moves upward following it. Furthermore, although an example in which the first support portion 21 and the second support portion 22 move upward has been described in FIGS. 3 and 4, the first support portion 21 and the second support portion 22 may move downward. Even in this case, the first support portion 21 and the second support portion 22 move in the same direction.

[0042] 3 and 4, one switching cycle includes a step in which the second support 22 moves its position relative to the first support 21 in the stacking direction while the first support 21 supports the stacked body 10 in a stationary state, and a step in which the first support 21 moves its position relative to the second support 22 in the stacking direction while the second support 22 supports the stacked body 10 in a stationary state.

[0043] For example, in the example of FIG. 3 , the transition from state (b) to state (c) in FIG. 3 is a process in which the second support 22 moves relative to the first support 21 in the stacking direction while the first support 21 supports the stack 10 in a stationary state. In the example of FIG. 4 , the transition from state (b) to state (c) in FIG. 4 is a process in which the first support 21 moves relative to the second support 22 in the stacking direction while the second support 22 supports the stack 10 in a stationary state. By configuring the first support 21 and the second support 22 to move in multiple cycles, the maximum stroke amount of the surface pressure applying mechanism 20 with respect to the module case 30 can be made larger than the stroke amount per cycle. Reducing the distance between the first support 21 and the second support 22 reduces the stroke amount per movement. Reducing the stroke per movement can reduce the size of the actuator body including the support portions, increase the number of layers in the stack 10, and increase the battery capacity.

[0044] Furthermore, the switching step of switching between a state in which the first support portion 21 supports the stack body 10 in a stationary state and a state in which the second support portion 22 supports the stack body 10 in a stationary state includes a step in which both the first support portion 21 and the second support portion 22 support the stack body 10 in a stationary state. For example, in Figures 3 and 4, states (a) and (c) in Figure 3 and states (a) and (c) in Figure 4 correspond to the step in which both the first support portion 21 and the second support portion 22 support the stack body 10 in a stationary state.

[0045] Next, an example of the state of the first support portion 21 and the second support portion 22 when they move downward will be described using FIG. 5 . FIG. 5 is a schematic diagram showing an example of the state of the first support portion 21 and the second support portion 22 when the support portion moves downward in the surface pressure applying mechanism according to this embodiment. As with FIGS. 3 and 4 , FIG. 5 does not depict the male and female threads as being spirally formed for the sake of simplicity. However, the male and female threads are spirally formed as shown in FIG. 2 . Therefore, each support portion moves vertically by rotating. FIG. 5 shows an example of a case where the laminate 10 is being charged, in which the surface pressure of the laminate 10 becomes excessive due to expansion of the laminate 10. In FIG. 5 , the state of the first support portion 21 and the second support portion 22 transitions from (a) to (b).

[0046] State (a) shows the state of the first support portion 21 and the second support portion 22 at time t. In state (a), the first support portion 21 and the second support portion 22 are in balance with the load of the stack 10 and the resultant force of the hydraulic pressure in the hydraulic chamber 24b and the tensile force of the spring 24a. Both the first support portion 21 and the second support portion 22 are supporting the stack 10 in a stationary state. As time passes from time t, the state of the first support portion 21 and the second support portion 22 transitions from state (a) at time t to state (b) at time t + Δt. At this time, the hydraulic pressure in the hydraulic chamber 24b decreases, and the load of the stack 10 causes the positions of the first support portion 21 and the second support portion 22 to move downward in the stacking direction. At this time, the first support portion 21 and the second support portion 22 do not become closer to each other, but move downward while being held by the holding portion 23 and separated from each other. When the battery is being charged, the support parts move downward to reduce the load so that the compressive load on the laminate 10 does not become excessive in response to the expansion of the laminate 10, but by separating the first support part 21 and the second support part 22 in advance, the surface pressure on the laminate 10 can be controlled by the movement of one of the first support parts 21. If the movement amount of the first support part 21 increases and it approaches the second support part 22, the second support part 22 is moved to ensure the distance between the first support part 21 and the second support part 22.

[0047] Next, an example of the state of the first support portion 21 and the second support portion 22 when they move will be described using FIG. 6. FIG. 6 is a schematic diagram showing an example of the state of the first support portion 21 and the second support portion 22 when the support portions are held stationary in the surface pressure applying mechanism according to this embodiment. Similarly to FIGS. 3 and 4, FIG. 6 does not depict the male and female threads as being spirally formed for the sake of simplicity. However, the male and female threads are spirally formed as shown in FIG. 2. Therefore, each support portion moves vertically by rotating. FIG. 6 shows an example in which the vehicle on which the laminate 10 is mounted is stopped. In FIG. 5, the state of the first support portion 21 and the second support portion 22 transitions from (a) to (b).

[0048] State (a) shows the state of the first support portion 21 and the second support portion 22 at time t. In state (a), the first support portion 21 and the second support portion 22 are held by the holding portion 23 in a state in which the first support portion 21 and the second support portion 22 are in contact with each other. Both the first support portion 21 and the second support portion 22 are stationary and support the stack 10. As time passes from time t, the state of the first support portion 21 and the second support portion 22 transitions from state (a) at time t to state (b) at time t+Δt. At this time, the hydraulic pressure in the hydraulic chamber 24b decreases, but because the first support portion 21 and the second support portion 22 are in a state in which they are in contact with each other at the contact portion 21e, the first support portion 21 and the second support portion 22 do not rotate and maintain their positions in the stacking direction. When the vehicle is stopped, by keeping the first support part 21 and the second support part 22 in contact, the surface pressure of the laminated body 10 can be maintained constant solely by the friction of the contact surfaces without relying on oil pressure, thereby preventing a drop in pressure due to oil leakage.

[0049] As described above, the surface pressure applying mechanism according to this embodiment applies a compressive load to a battery stack in the stacking direction to apply surface pressure, and includes first and second support parts positioned relative to the stack in the stacking direction to support the stack, a holder for holding the first and second support parts, and a spring and hydraulic chamber positioned between the first and second support parts to connect the first and second support parts. The stack is housed in a module case, and the first and second support parts are male-female coupled to the holder so as to be rotatable around the stacking direction as an axis of rotation. When the stack expands or contracts, if one of the support parts is held stationary by the holder, the other support part can rotate around the axis of rotation, thereby moving in the stacking direction. This allows the surface pressure applying mechanism to be made smaller.

[0050] Furthermore, in the surface pressure applying mechanism according to this embodiment, the distance between the first support part and the second support part changes in a step of moving the first support part in the stacking direction by rotating the second support part while the first support part is supporting the stack in a stationary state, or in a step of moving the first support part in the stacking direction by rotating the second support part while supporting the stack in a stationary state. As a result, while one support part is supporting the stack, the position of the other support part can be moved, thereby moving the position at which the other support part is fixed.

[0051] Furthermore, in the surface pressure applying mechanism according to this embodiment, in the process of rotating the first support part to move in the stacking direction and the process of rotating the second support part to move in the stacking direction, the stroke amount of the one support part in the rotating state moving in the stacking direction is smaller than the maximum stroke amount that the one support part in the rotating state can move in the stacking direction. This reduces the stroke amount in one switching process, making it possible to reduce the size of the surface pressure applying mechanism and increase the number of stacked layers in the stack, thereby increasing the battery capacity.

[0052] Furthermore, in the surface pressure applying mechanism according to this embodiment, the direction in which the first support part moves when the second support part is stationary and supporting the stack is the same as the direction in which the second support part moves when the first support part is stationary and supporting the stack, which allows a predetermined distance to be maintained between the support parts, and therefore allows the movement of each support part to be repeated.

[0053] Furthermore, in the surface pressure applying mechanism according to this embodiment, the first support member and the second support member repeatedly execute a switching cycle, which includes a step in which the second support member moves relative to the first support member in the stacking direction while the first support member is stationary and supporting the stack, and a step in which the first support member moves relative to the second support member in the stacking direction while the second support member is stationary and supporting the stack. This configuration, which repeatedly executes the switching cycle, makes it possible to increase the maximum stroke amount relative to the stroke amount in a single switching step. By reducing the stroke amount in a single switching step, the size of the surface pressure applying mechanism can be reduced, and the number of stacked layers in the stack can be increased, thereby increasing battery capacity.

[0054] Furthermore, in the surface pressure applying mechanism according to this embodiment, the load applied from the laminated body is applied to the second support portion via the first support portion, which allows a large stroke to be achieved by repeating small strokes.

[0055] Furthermore, in the surface pressure applying mechanism according to this embodiment, the holding part has a female screw part arranged along the stacking direction, and at least one of the first support part and the second support part has a male screw part that engages with the female screw part, and moves in the stacking direction by rotating around the rotation axis with the male screw part engaged with the female screw part. This allows the support part to change its position in the stacking direction while rotating along the female screw part of the holding part.

[0056] Furthermore, in the surface pressure applying mechanism according to this embodiment, the frictional force acting on the male thread portion of at least one of the first support portion and the second support portion when moving in the contraction direction of the stack is smaller than the frictional force acting on the male thread portion when moving in the expansion direction of the stack, which makes it easier for the support portion to maintain its position in the stacking direction in response to expansion of the stack when stationary, and to change its position in the stacking direction when movable.

[0057] Furthermore, in the surface pressure applying mechanism according to this embodiment, the male thread portion of at least one of the first support portion and the second support portion is slidably engaged with the female thread portion, and the coefficient of friction of the sliding surface of the male thread portion in contact with the female thread portion when moving in the contraction direction is smaller than the coefficient of friction of the sliding surface of the male thread portion in contact with the female thread portion when moving in the expansion direction. This makes it easier for the support portion to maintain its position in the stacking direction in response to expansion of the stack when stationary, and easier to change its position in the stacking direction when movable.

[0058] Furthermore, in the surface pressure applying mechanism according to this embodiment, the first support part and the second support part are such that, as the hydraulic pressure in the hydraulic chamber increases, one support part in the rotating state moves in the stacking direction away from the other support part in the stationary state due to the hydraulic pressure, and as the hydraulic pressure decreases, one support part in the rotating state moves in the stacking direction toward the other support part in the stationary state due to the spring. This allows the positions of the support parts in the stacking direction to be adjusted.

[0059] Furthermore, in the surface pressure applying mechanism according to this embodiment, the main surfaces of the first support portion and the second support portion are arranged to face each other, the main surface of the first support portion has a first joint portion that joins with one end of the spring, the main surface of the second support portion has a second joint portion that joins with the other end of the spring, the main surfaces of the first support portion and / or the second support portion have abutment portions that abut against each other when the first support portion and the second support portion are brought closer by the spring, the abutment portions are located on a portion of the main surface of the first support portion other than the first joint portion and / or a portion of the main surface of the second support portion other than the second joint portion, and are formed to protrude from the main surface of the first support portion and / or the main surface of the second support portion so that the first joint portion and the second joint portion are spaced apart by a predetermined distance or more when the main surfaces of the first support portion and the second support portion abut at the abutment portions, thereby preventing damage to the spring.

[0060] Furthermore, in the surface pressure applying mechanism according to this embodiment, the first support portion and the second support portion are held by the holding portion in a state in which the first support portion and the second support portion are spaced apart from each other while the stack is being charged. As a result, when the positions of the support portions in the stacking direction are moved in the expansion direction so that the compressive load on the stack does not become excessive in response to the expansion of the stack while the stack is being charged, the support portions are spaced apart in advance, and the surface pressure on the stack can be controlled by moving only one of the support portions.

[0061] Furthermore, in the surface pressure applying mechanism according to this embodiment, the stack is mounted on the vehicle as a battery, and the first support portion and the second support portion are held by the holding portion in a state in which the first support portion and the second support portion are in contact with each other while the vehicle is stopped. As a result, by keeping the support portions in contact with each other when the vehicle is stopped, a constant surface pressure on the stack can be maintained only by the frictional force of the screw portion, not by oil pressure, and a decrease in surface pressure due to oil leakage can be prevented.

[0062] Furthermore, in the surface pressure applying mechanism according to this embodiment, the switching step of switching between a state in which the first support unit is stationary and supporting the stack and a state in which the second support unit is stationary and supporting the stack includes a step of supporting the stack with both the first support unit and the second support unit stationary. This prevents the surface pressure of the stack from being lost. Because the load of the stack 10 is borne by the support units that support the two stacks 10, the burden on each support unit can be reduced, allowing the support unit to be made smaller.

[0063] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above-described embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0064] 1...Battery module 10...Laminate 20...Surface pressure applying mechanism 21...First support part 22…Second support part 23...Holding part 24...Connection part 24a...Spring 24b...Hydraulic chamber 30...Module case

Claims

1. A surface pressure applying mechanism that applies a compressive load to a stack of batteries in a stacking direction to apply surface pressure, a first support portion and a second support portion positioned in the stacking direction relative to the stack to support the stack; a holding portion for holding the first support portion and the second support portion; a spring and hydraulic chamber located between the first support portion and the second support portion and connecting the first support portion and the second support portion, The stack is housed in a module case, The first support portion and the second support portion are a male-female coupling with the holding portion so as to be rotatable about a rotation axis in the stacking direction; When the laminate expands and contracts, if one of the support parts is held by the holding part in a stationary state, the other support part can rotate around the rotation axis, thereby moving in the stacking direction.

2. The surface pressure applying mechanism according to claim 1, A surface pressure applying mechanism in which the distance between the first support portion and the second support portion changes in a step of moving in the stacking direction by rotating the second support portion while the first support portion supports the stack in the stationary state, or in a step of moving in the stacking direction by rotating the first support portion while the second support portion supports the stack in the stationary state.

3. 3. The surface pressure applying mechanism according to claim 1 or 2, a surface pressure applying mechanism in which, in a step of rotating the first support part to move in the stacking direction and a step of rotating the second support part to move in the stacking direction, a stroke amount by which the one support part in the rotating state moves in the stacking direction is smaller than a maximum stroke amount by which the one support part in the rotating state can move in the stacking direction.

4. 3. The surface pressure applying mechanism according to claim 1 or 2, A surface pressure applying mechanism in which the direction of movement of the first support portion when the second support portion is supporting the stack in the stationary state is the same as the direction of movement of the second support portion when the first support portion is supporting the stack in the stationary state.

5. 3. The surface pressure applying mechanism according to claim 1 or 2, The first support portion and the second support portion repeatedly perform a switching cycle, The switching cycle comprises: a step of moving the second support portion relative to the first support portion in the stacking direction while the first support portion supports the stack in the stationary state; a step of moving the position of the first support portion relative to the second support portion in the stacking direction while the second support portion supports the stack in the stationary state.

6. 3. The surface pressure applying mechanism according to claim 1 or 2, a surface pressure applying mechanism that applies a load applied from the stack to the second support portion via the first support portion;

7. 3. The surface pressure applying mechanism according to claim 1 or 2, the holding portion includes a female screw portion arranged along the stacking direction, At least one of the first support portion and the second support portion is A male screw portion is provided which engages with the female screw portion, a surface pressure applying mechanism that moves in the stacking direction by rotating around the rotation axis with the male thread portion engaged with the female thread portion;

8. The surface pressure applying mechanism according to claim 7, At least one of the first support portion and the second support portion is A surface pressure applying mechanism in which the friction force acting on the male thread portion when the laminate moves in a contraction direction is smaller than the friction force acting on the male thread portion when the laminate moves in an expansion direction.

9. The surface pressure applying mechanism according to claim 8, At least one of the first support portion and the second support portion is The male screw portion is slidably engaged with the female screw portion, A surface pressure applying mechanism in which the coefficient of friction of the sliding surface of the male thread portion in contact with the female thread portion when moving in the contraction direction is smaller than the coefficient of friction of the sliding surface of the male thread portion in contact with the female thread portion when moving in the expansion direction.

10. 3. The surface pressure applying mechanism according to claim 1 or 2, The first support portion and the second support portion are the greater the hydraulic pressure in the hydraulic chamber, the more the other support portion in the rotating state moves in the stacking direction so as to move away from the one support portion in the stationary state due to the hydraulic pressure; a surface pressure applying mechanism that, as the hydraulic pressure decreases, moves the other support portion in the rotating state in the stacking direction by the spring so as to approach the one support portion in the stationary state;

11. The surface pressure applying mechanism according to claim 10, a main surface of the first support portion and a main surface of the second support portion are arranged to face each other, a main surface of the first support portion has a first joining portion that joins with one end of the spring; a main surface of the second support portion has a second joining portion that joins with the other end of the spring; a main surface of the first support portion and / or a main surface of the second support portion have an abutment portion that abuts against each other when the first support portion and the second support portion are brought closer by the spring, The abutment portion is located in a portion of the main surface of the first support portion other than the first joint portion and / or in a portion of the main surface of the second support portion other than the second joint portion, a surface pressure applying mechanism formed to protrude from the main surface of the first support portion and / or the main surface of the second support portion so that the first joint portion and the second joint portion are spaced apart by a predetermined length or more when the main surface of the first support portion and the main surface of the second support portion are in contact at the contact portion.

12. The surface pressure applying mechanism according to claim 10, The first support portion and the second support portion are a surface pressure applying mechanism in which the first support portion and the second support portion are held by the holding portion in a state separated from each other while the stack is being charged;

13. The surface pressure applying mechanism according to claim 10, The laminate is mounted on a vehicle as a battery, The first support portion and the second support portion are a surface pressure applying mechanism that is held by the holding portion in a state in which the first support portion and the second support portion are in contact with each other while the vehicle is stopped;

14. 3. The surface pressure applying mechanism according to claim 1 or 2, A surface pressure applying mechanism in which a switching process for switching between a state in which the first support portion supports the stack in the stationary state and a state in which the second support portion supports the stack in the stationary state includes a process in which both the first support portion and the second support portion support the stack in the stationary state.

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