CN112599831B

CN112599831B - Cell stack tightening device

Info

Publication number: CN112599831B
Application number: CN202011462362.4A
Authority: CN
Inventors: 裴后昌; 肖晨光; 宋少云; 王旺平
Original assignee: Wuhan Polytechnic University
Current assignee: Wuhan Polytechnic University
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2022-04-29
Anticipated expiration: 2040-12-11
Also published as: CN112599831A

Abstract

The invention discloses a cell stack tightening device, which comprises a cell pack, an upper end plate and a lower end plate, wherein the cell pack is arranged between the upper end plate and the lower end plate, the cell stack tightening device comprises a binding band and a locking mechanism, the binding band is wound on two sides of the cell stack, the locking mechanism comprises a bottom plate, a rotating shaft and a clamping plate, the rotating shaft and the clamping plate are arranged on the bottom plate, the first end of the binding band is connected with the clamping plate, the second end of the binding band is connected with the rotating shaft, and the rotation of the rotating shaft is used for driving the second end of the binding band to be close to the first end of the binding band, so that the periphery of the cell stack is tightened by the binding band. The cell stack tightening device can drive the second end of the binding band to move towards the first end of the binding band only by adopting the rotation of the rotating shaft in the locking mechanism, thereby tightening the cell stack, being simple, convenient and easy to operate, saving energy and being suitable for more working environments.

Description

Cell stack tightening device

Technical Field

The invention relates to the technical field of battery assembly, in particular to a battery stack tightening device.

Background

A Proton Exchange Membrane Fuel Cell (PEMFC) is a power generation device that can directly convert chemical energy in gas into electric energy without combustion, and has high energy density, no use of flowing corrosive electrolyte, and simple structure, thus having good development prospects compared with other fuel cells, but a single PEMFC has far failed to meet the requirements of specific equipment, and thus often needs to be assembled into a battery pack. That is, individual PEMFCs are constructed in series or in parallel according to the voltage or current requirements of a particular plant, and the framework materials thereof generally include: 1) end plate: the outermost side of the battery is distributed with an air inlet, an air outlet and the like, and the battery pack is often assembled, and the battery pack is mainly used for fixing the battery pack, namely a total inlet for fuel gas to enter and exit; 2) taking a battery pack: under the end plate, the battery pack is used for collecting current generated by reaction in the battery and guiding the current to the battery pack; 3) bipolar plate: the framework structure of the novel proton exchange membrane fuel cell has high compactness and can ensure the flatness and the verticality among cells.

In previous conventional designs, the stack was joined together with bipolar plates and MEA components by tie rods. Two terminal plates at both ends of the stack provide a fixed plane. The two plates are joined together and pressure is applied to the cell. Springs, such as spiral or butterfly springs, are typically placed between the tie-bar clasp and the end plate to facilitate movement of the end plate to compensate for thermal expansion and contraction of the stack assembly. The draw bar structure has the defects of more parts and large occupied space. Subsequently, placing tie rods at the central manifold may reduce the required external volume, but still occupy the volume at the central manifold, thereby affecting the stack design. In addition, some tie rods and good balancing assemblies are required in combination to ensure uniform cell compression. Inspection and periodic maintenance are necessary.

And then the electric pile assembly is bound together by a binding band for improvement, so that the design is more compact and the parts are fewer. However, manufacturing tolerances cause the straps and the cell stack to be of different lengths. Therefore, the straps need to be cut to length and then welded together, or an adjustment rod and screw may be added to the end of the straps to adjust for differences in the length of the fuel cell assembly. The latter is preferable because it allows repair and reuse of parts, reducing the number of parts, and reducing the maintenance straps is a compromise. In either case, the stack length defined by the end plates varies with the manufacturing tolerances of the plates, so that it is not possible to maintain a maximum length while ensuring optimum stack compression. The existing fuel cell stack assembly mechanism generally has the defects of low assembly efficiency, large manual operation error, low repeatability, difficulty in effectively controlling stack compression displacement and the like.

Disclosure of Invention

The invention mainly aims to provide a cell stack binding device, aiming at solving the technical problems that the structure of the cell stack binding device is complicated and the compression displacement of a cell stack is controlled in the prior art.

In order to achieve the above object, the cell stack tightening device provided by the present invention includes a cell pack, an upper end plate and a lower end plate, the cell pack is disposed between the upper end plate and the lower end plate, the cell stack tightening device includes a binding band and a locking mechanism, the binding band is wound around two sides of the cell stack, the locking mechanism includes a base plate, and a rotating shaft and a clamping plate disposed on the base plate, a first end of the binding band is connected to the clamping plate, a second end of the binding band is connected to the rotating shaft, and rotation of the rotating shaft is used to drive a second end of the binding band to be close to the first end of the binding band, so that the binding band tightens the periphery of the cell stack.

Preferably, the bandage is a U-shaped structure, a containing cavity for containing the battery stack is formed in the bandage, a first boss is arranged at the first end of the bandage, a second boss is arranged at the second end of the bandage, the first boss extends towards the second boss, a first clamping hole is formed in the first boss, a second clamping hole is formed in the second boss, the first clamping hole is connected with the clamping plate in a clamped mode, and the second clamping hole is connected with the rotating shaft in a clamped mode.

Preferably, the clamping plate faces one side of the bottom plate and is provided with a first clamping block, the first clamping block is clamped with the first clamping hole, the extending direction of the rotating shaft is consistent with the length direction of the bottom plate, the rotating shaft faces one side of the bottom plate and is provided with a second clamping block, and the second clamping block is clamped with the second clamping hole.

Preferably, a buffer groove is formed in the rotating shaft, the extending direction of the buffer groove is consistent with the length direction of the rotating shaft, the second clamping block corresponds to the buffer groove, and the second clamping block is detachably connected with the groove bottom of the buffer groove.

Preferably, the both sides of cardboard are provided with the buckle, locking mechanism still includes spacing subassembly, spacing subassembly including set up in the spacing platform of bottom plate top, spacing platform include the limiting plate, set up in the mounting panel and the connection of limiting plate both sides the mounting panel with the connecting plate of limiting plate, the mounting panel with the connection can be dismantled to the bottom plate, the mounting panel with form between the bottom plate and dodge the district of dodging of cardboard, the mounting hole has been seted up on the connecting plate, the buckle with the mounting hole joint.

Preferably, the buckle is a semi-arc structure, one side of the buckle, which deviates from the clamping plate, is a convex surface, and anti-skidding teeth are arranged on the convex surface.

Preferably, the bottom plate is provided with a sliding groove corresponding to the first clamping block, one end of the first clamping block close to the bottom plate is slidably arranged in the sliding groove, and the number of the first clamping blocks and the number of the sliding grooves are both two and are in one-to-one correspondence.

Preferably, the bottom plate is provided with two first support frames which are arranged at intervals, through holes are formed in the two first support frames, bearings are arranged in the through holes, and two ends of the rotating shaft are respectively sleeved in the two bearings.

Preferably, the limiting assembly further comprises a second supporting frame, a ratchet wheel and a pawl meshed with the ratchet wheel, the second supporting frame is arranged on the bottom plate, and the center of the ratchet wheel is connected with one end of the rotating shaft.

Preferably, the upper end plate is provided with a groove, the bottom plate is arranged in the groove, and the bottom plate is detachably connected with the groove bottom of the groove.

In the cell stack binding device, the upper end plate is covered on the upper end of the cell pack, and the lower end plate is covered under the cell pack, so that the upper end plate and the lower end plate seal the two ends of the cell pack to form a cell stack. Adopt the bandage to fix it in the side around the battery pile, for preventing that the bandage from sliding around along when using, set up locking mechanism on the upper end plate, the first end and the cardboard of bandage are connected, and the second end and the pivot of bandage are connected, and when the bandage tightened with the side around the battery pile, the rotation of pivot is used for driving the second end of bandage and holds the first end that is close to the bandage to apply certain pretightning force for the bandage, thereby prevent that not hard up phenomenon from appearing in the battery pile. The cell stack tightening device can drive the second end of the binding band to move towards the first end of the binding band only by adopting the rotation of the rotating shaft in the locking mechanism, thereby tightening the cell stack, being simple, convenient and easy to operate, saving energy and being suitable for more working environments.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic view of a stack tightening device tightening a stack according to an embodiment of the present invention;

FIG. 2 is a schematic view of a locking mechanism of a cell stack tightening device according to an embodiment of the present invention;

FIG. 3 is a schematic view of a portion of a locking mechanism of a cell stack tightening device according to an embodiment of the present invention;

FIG. 4 is a schematic view showing the structure of a binding band in the cell stack binding apparatus according to the embodiment of the present invention;

FIG. 5 is a schematic view of a clamping plate of the cell stack fastening device according to one embodiment of the present invention;

FIG. 6 is a schematic structural view of a position-limiting table in the cell stack tightening device according to an embodiment of the present invention;

fig. 7 is a schematic structural view of a bottom plate in a cell stack tightening device according to an embodiment of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	Binding band	231	Second clamping block
11	Containing cavity	232	Buffer tank
				12	First boss	24	Limiting assembly
13	Second boss	241	Limiting table
				14	First clamping hole	2411	Limiting plate
15	Second clamping hole	2412	Mounting plate
				20	Locking mechanism	2413	Connecting plate
21	Card board	2414	Avoidance zone
				211	First clamping block	2415	Mounting hole
212	Buckle	242	Second support frame
				2121	Anti-skid tooth	243	Ratchet wheel
22	Base plate	244	Pawl
				221	Sliding chute	30	Battery pack
222	First support frame	40	Upper end plate
				223	Bearing assembly	50	Lower end plate
23	Rotating shaft

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The description of the orientations of "up", "down", "left", "right", "front", "back", etc. in the present invention, with reference to the orientation shown in fig. 1, is merely for explaining the relative positional relationship between the components in the posture shown in fig. 1, and if the specific posture is changed, the directional indication is changed accordingly.

The invention provides a cell stack tightening device.

As shown in fig. 1, in an embodiment of the present invention, the cell stack tightening device is used for tightening a cell stack, the cell stack includes a cell pack 30, an upper end plate 40 and a lower end plate 50, the cell pack 30 is disposed between the upper end plate 40 and the lower end plate 50, the cell stack tightening device includes a strap 10 and a locking mechanism 20, the strap 10 is wound on two sides of the cell stack, the locking mechanism 20 is disposed on the upper end plate 40, the locking mechanism 20 includes a catch plate 21, a bottom plate 22 and a rotating shaft 23 disposed on the bottom plate 22, a first end of the strap 10 is connected with the catch plate 21, a second end of the strap 10 is connected with the rotating shaft 23, and rotation of the rotating shaft 23 is used for driving the second end of the strap 10 to tighten toward the first end of the strap 10, so that the strap 10 tightens the periphery of the cell stack. In this embodiment, the upper end plate 40 is covered on the upper end of the battery pack 30, and the lower end plate 50 is covered on the lower side of the battery pack 30, so that the upper and

lower end plates

40 and 50 enclose both ends of the battery pack 30 to form a battery stack. The binding bands 10 are fixed at the front and rear sides of the battery pack by using the binding bands 10, in order to prevent the binding bands 10 from sliding back and forth when in use, the locking mechanism 20 is provided on the upper end plate 40, then the free ends of the binding bands 10 are connected in the locking mechanism 20, when the binding bands 10 bind the front and rear sides of the battery pack, the rotation of the rotating shaft 23 is used for driving the second ends of the binding bands 10 to be close to the first ends of the binding bands 10, so that a certain pre-tightening force is applied to the binding bands 10, and the battery pack 30 is prevented from being loosened. The cell stack tightening device can drive the second end of the binding band to move towards the first end of the binding band only by adopting the rotation of the rotating shaft in the locking mechanism, thereby tightening the cell stack, being simple, convenient and easy to operate, saving energy and being suitable for more working environments.

As shown in fig. 4, the binding band 10 is of a U-shaped structure, a containing cavity 11 for containing the battery stack is formed in the binding band 10, a first boss 12 is arranged at a first end of the binding band 10, a second boss 13 is arranged at a second end of the binding band 10, the first boss 12 extends towards the second boss 13, a first clamping hole 14 is formed in the first boss 12, a second clamping hole 15 is formed in the second boss 13, the first clamping hole 14 is clamped with the clamping plate 21, and the second clamping hole 15 is clamped with the rotating shaft 23. In a preferred embodiment, the binding band 10 is of a U-shaped structure, the first end of the binding band 10 is a free end, and the free end is in an open arrangement, and a containing cavity 11 for fixing the battery stack is formed in the U-shaped binding band 10. A first boss 12 and a second boss 13 are provided at the free end of the strap 10, and the first boss 12 and the second boss 13 are provided at an interval opposite to each other, and both the first boss 12 and the second boss 13 extend in the front-rear direction. The first boss 12 is provided with a first clamping hole 14, the second boss 13 is provided with two second clamping holes 15, when the cell stack is tightened, the first clamping hole 14 is clamped with the clamping plate 21, and the second clamping hole 15 is clamped with the rotating shaft 23, so that the locking mechanism 20 locks the bandage 10 to prevent the bandage 10 from sliding.

As shown in fig. 2, the clamping plate 21 is disposed at one end of the bottom plate 22, a first clamping block 211 is disposed on one side of the clamping plate 21 facing the bottom plate 22, the first clamping block 211 is clamped with the first clamping hole 14, the rotating shaft 23 extends along the length direction of the bottom plate 22, a second clamping block 231 is disposed on one side of the rotating shaft 23 facing the bottom plate 22, and the second clamping block 231 is clamped with the second clamping hole 15.

In the preferred embodiment, a first locking hole 14 and a second locking hole 15 are respectively formed at the head end and the tail end of the binding band 10, wherein the first locking hole 14 on the left side is matched with the first locking block 211, the binding band 10 is locked due to the fact that the second locking block 231 is in threaded connection with the rotating shaft 23 and protrudes out of the plane of the rotating shaft 23 at the force bearing side of the binding band 10, and the second end of the binding band 10 is matched with the second locking block 231. When the battery pack 30 is tightened, the rotating shaft 23 is directly rotated, and the rotating shaft 23 drives the second latch 231 to move towards the first latch 211, so as to drive the second end of the binding band 10 to move towards the first end of the binding band 10, thereby achieving the purpose that the binding band 10 tightens the battery pack 30. As shown in fig. 3, a plane is cut off from the rotating shaft 23 to form a buffer groove 232, the extending direction of the buffer groove 232 is the same as the length direction of the rotating shaft 23, the second latch 231 is disposed corresponding to the buffer groove 232, and the second latch 231 is detachably connected to the bottom of the buffer groove 232.

As shown in fig. 6, two sides of the catch plate 21 are provided with the buckles 212, the locking mechanism 20 further includes a limiting assembly 24, the limiting assembly 24 includes a limiting platform 241 disposed above the bottom plate 22, the limiting platform 241 includes a limiting plate 2411, a mounting plate 2412 disposed on two sides of the limiting plate 2411, and a connecting plate 2413 connecting the mounting plate 2412 and the limiting plate 2411, the mounting plate 2412 is detachably connected to the bottom plate 22, an avoiding area 2414 for inserting the catch plate 21 is formed between the mounting plate 2412 and the bottom plate 22, a mounting hole 2415 is formed on the connecting plate 2413, and the buckles 212 are connected to the mounting hole 2415 in a snap-fit manner.

In a preferred embodiment, when installing, the locking mechanism 20 is placed in the groove on the upper end plate 40 to prevent the binding band 10 from sliding up and down, then the first end of the binding band 10 is placed on the two first blocks 211 protruding from the clamping plate 21, then the buckle 212 is pushed into the position-limiting table 241 to be clamped, so that the binding band 10 is clamped between the mounting plate 2412 and the bottom plate 22, then the second end of the binding band 10 is clamped into the gap between the rotating shaft 23 and the second block 231, and the rotating shaft 23 is rotated by using a wrench to tighten the binding band 10 until enough pre-tightening force is applied. When the binding band 10 is loosened due to plastic deformation occurring during the use of the battery pack 30, the binding band can be tightened again only by rotating the rotating shaft 23 again.

As shown in fig. 5, the clip 212 is a semi-arc structure, and one side of the clip 212 facing away from the card board 21 is a convex surface, and the convex surface is provided with anti-slip teeth 2121. In a preferred embodiment, when the strap 10 is used, the buckle 212 is automatically ejected only by pressing the buckle 212 at the catch plate 21, and since the buckle teeth of the buckle 212 are designed to be arc-shaped and the anti-slip teeth 2121 are added on the edge, the movement of the buckle 212 is limited when the buckle 212 is released, so that excessive rigid impact cannot be generated, and the damage to the single battery is avoided. When the buckle 212 is opened, the battery pack cannot be directly ejected, but gradually exits the clamping plate 21 in a gradual step mode, so that the rigid impact on the battery during disassembly is reduced, and the effect of protecting the single battery pack 30 is achieved.

As shown in fig. 7, the bottom plate 22 is provided with a sliding groove 221 corresponding to the first latch 211, one end of the first latch 211 close to the bottom plate 22 is slidably disposed in the sliding groove 221, and the number of the first latches 211 and the number of the sliding grooves 221 are both two and are in one-to-one correspondence. In a preferred embodiment, two sliding slots 221 are formed in the bottom plate 22, the width of the sliding slot 221 is equal to the width of the opening of the binding band 10, and the second latch 231 at the bottom end of the latch 212 passes through the opening of the binding band 10 and just fits into the opening of the bottom plate 22, so that the latch 212 can move freely on the bottom plate 22.

In addition, two first support frames 222 are arranged on the bottom plate 22 at intervals, through holes are formed in the two first support frames 222, bearings 223 are arranged in the through holes, and two ends of the rotating shaft 23 are respectively sleeved in the two bearings 223. The position-limiting assembly 24 further includes a second supporting frame 242, a ratchet 243 and a pawl 244 engaged with the ratchet 243, the second supporting frame 242 is disposed on the bottom plate 22, and the center of the ratchet 243 is connected to one end of the rotating shaft 23. In the preferred embodiment, two first supporting frames for supporting the bearings 223 are fixed on the bottom plate 22, wherein two ends of the rotating shaft 23 respectively pass through the two bearings 223 fixed on the two first supporting frames 222, the end of the rotating shaft 23 is connected with the ratchet 243, the ratchet 243 and the pawl 244 form a ratchet 243 mechanism, and the ratchet 243 is embedded with a small spring to provide restoring force, so that the bearings 223 can only rotate in one direction, and can not rotate in the opposite direction to loosen the binding belt 10. After the binding belt 10 is assembled, the rotating shaft 23 is rotated by a wrench to lock the binding belt 10 to provide an assembling force for the battery, the rotating shaft 23 can only rotate in a single direction due to the action of the ratchet 243, so that the binding belt 10 can only be tightened and cannot be loosened due to a mechanical structure, and when the binding belt 10 fails due to deformation in an experiment, the binding belt 10 can be restored to work only by rotating the rotating shaft 23 and then increasing pretightening force. When disassembly is needed, the buckle 212 can be automatically ejected out only by loosening the buckle 212, the bandage 10 can be automatically loosened, and the bandage 10 can be taken off by removing the bandage 10 on the rotating shaft 23.

Furthermore, the upper end plate 40 is provided with a groove (not shown), the bottom plate 22 is arranged in the groove, and the bottom plate 22 is detachably connected with the bottom of the groove. The edge of the upper end plate 40 of the battery stack is designed to be of a trapezoidal structure, so that the uneven stress of the binding band 10 caused by too small angle when the binding band 10 is turned is reduced, the upper end and the lower end of the upper end plate 40 are provided with grooves, the bottom plate 22 is connected with the groove bottoms of the grooves through fasteners, and the locking mechanism 20 and the binding band 10 are prevented from falling off in relative motion and uneven stress is prevented.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The utility model provides a tight device is restrainted to battery pile, the battery pile includes battery package, upper end plate and lower end plate, the battery package set up in the upper end plate with between the lower end plate, a serial communication port, tight device is restrainted to battery pile includes bandage and locking mechanism, the bandage is around locating the both sides of battery pile, locking mechanism include the bottom plate and set up in pivot and cardboard on the bottom plate, the first end of bandage with the cardboard is connected, the second end of bandage with the pivot is connected, the rotation of pivot is used for driving the second end of bandage is close to the first end of bandage, so that the bandage will the periphery of battery pile is tightened.

2. The stack lacing apparatus of claim 1, wherein the strap is U-shaped, wherein a cavity is formed in the strap for receiving the stack, a first protrusion is disposed at a first end of the strap, a second protrusion is disposed at a second end of the strap, the first protrusion extends toward the second protrusion, a first hole is disposed on the first protrusion, a second hole is disposed on the second protrusion, the first hole is engaged with the clamping plate, and the second hole is engaged with the shaft.

3. The cell stack tightening device according to claim 2, wherein a first clamping block is disposed on a side of the clamping plate facing the bottom plate, the first clamping block is clamped with the first clamping hole, the extending direction of the rotating shaft is identical to the length direction of the bottom plate, a second clamping block is disposed on a side of the rotating shaft facing the bottom plate, and the second clamping block is clamped with the second clamping hole.

4. The cell stack tightening device according to claim 3, wherein the rotation shaft is provided with a buffer groove, the extending direction of the buffer groove coincides with the length direction of the rotation shaft, the second engaging piece is disposed corresponding to the buffer groove, and the second engaging piece is detachably connected to the bottom of the buffer groove.

5. The battery pack tightening device according to claim 3, wherein the two sides of the clamping plate are provided with buckles, the locking mechanism further comprises a limiting component, the limiting component comprises a limiting table arranged above the bottom plate, the limiting table comprises a limiting plate, mounting plates arranged on two sides of the limiting plate, and a connecting plate connecting the mounting plates and the limiting plate, the mounting plates are detachably connected with the bottom plate, an avoiding area for avoiding the clamping plate is formed between the mounting plates and the bottom plate, the connecting plate is provided with mounting holes, and the buckles are clamped with the mounting holes.

6. The stack lacing apparatus of claim 5, wherein the latch is in the form of a semi-arc, and wherein a side of the latch facing away from the clamping plate is a raised surface, and wherein the raised surface has anti-slip teeth thereon.

7. The stack binding device according to any one of claims 3 to 6, wherein the bottom plate has a sliding slot corresponding to the first engaging piece, one end of the first engaging piece close to the bottom plate is slidably disposed in the sliding slot, and the number of the first engaging pieces and the number of the sliding slots are two and are in one-to-one correspondence.

8. The cell stack tightening device according to any one of claims 1 to 6, wherein the base plate is provided with two first support frames spaced apart from each other, the two first support frames each have a through hole, a bearing is provided in the through hole, and both ends of the shaft are respectively fitted in the two bearings.

9. The stack lacing apparatus of any one of claims 5 or 6, wherein the limiting assembly further comprises a second support frame, a ratchet wheel, and a pawl engaged with the ratchet wheel, the second support frame is disposed on the base plate, and a center of the ratchet wheel is connected to one end of the shaft.

10. The stack tie-down apparatus of any one of claims 1-6, wherein the upper end plate defines a recess, the bottom plate is disposed within the recess, and the bottom plate is removably coupled to a bottom of the recess.