Patent Description:
The present invention relates to a transfer device for a unit cell, which transfers unit cells, in which electrode (negative electrode and positive electrode) and separators are stacked in a predetermined number and order, and more particularly, to a transfer device for a unit cell, in which the unit cell is capable of being minimized in wear and damage due to frictional force generated at a contact portion with a rail during the transferring.

The prior art pertinent to the present invention is given particularly by<CIT> and <CIT>, which refer to conveyor systems having protrusions on one or more rails. The demands for high-efficiency secondary batteries are rapidly increasing in the mobile device and electric vehicle fields. Among such the secondary batteries, a lithium secondary battery having high energy density, maintaining a relatively high voltage, and having a low self-discharge rate is commercially widely used, and research and development for improving performance is actively being conducted.

The secondary battery has a structure in which an electrode assembly and an electrolyte are embedded in a case such as a can or a pouch. The electrode assembly has a structure in which positive electrodes, separators, and negative electrodes are repeatedly stacked. In general, the electrode assembly may be classified into a winding type electrode assembly in which positive electrodes, separators, and negative electrodes, which are in the stacked state, are rolled to be embedded in a case and a stack type electrode assembly in which positive electrodes, separators, and negative electrodes, each of which is cut to a predetermined size, are stacked.

Since the winding type electrode assembly has a spirally wound structure, the winding type electrode assembly is suitable for being mounted on a cylindrical battery, but is disadvantageous in space utilization for a prismatic or pouch type battery. On the other hand, since the stack type electrode assembly is adjusted in size when the electrode and the separator are cut, the prismatic shape fitted with the case is easily obtained, but a manufacturing process is relatively complicated, and the stack type electrode assembly is relatively vulnerable to an external impact.

In addition, after a bicell (having a stacked structure of positive electrode/separator/negative electrode, wherein electrodes disposed at the uppermost end and the lowermost end are the same) and/or a half-cell (having a stacked structure of positive electrode/separator/negative electrode, wherein electrodes disposed at the uppermost end and the lowermost end are different from each other) are manufactured into unit cells, each of which has an appropriate size, so that advantages of the winding type electrode assembly and advantages of the stack type electrode assembly are combined with each other, a stack & folding process of manufacturing an electrode assembly by folding a folding separator after the unit cells are arranged at intervals on the folding separator has been developed.

In the stack & folding process, after pre-manufacturing a unit cell having a pre-planned structure, the unit cells are transferred one by one from a starting position, at which the unit cells are stored, to a target position, and then, the unit cells are placed on the folding separator so as to be put into a manufacturing device for folding the folding separator.

Here, the unit cells are transferred through a transfer device. Referring to <FIG> and <FIG> that schematically illustrates a transfer device for a unit cell according to the related art, when a unit cell <NUM> seated on a transfer device <NUM> is transferred up to a target position, the unit cell is gripped by a gripper <NUM> having a clamp structure and then additionally moves by the gripper <NUM> and is put into a roller <NUM> provided at an inlet of the manufacturing device.

Here, the transfer device <NUM> comprises a conveyor <NUM>, which travels to one side to transfer the seated unit cell <NUM> when the unit cell <NUM> is seated, and first and second rails 3a and 3b respectively disposed at one side and the other side of the conveyor <NUM>.

The conveyor <NUM> has a structure in which a belt is coupled to wind a plurality of rollers, which are similar to a caterpillar track, at once, and the belt is configured to continuously rotate while the rollers rotate. Thus, when the unit cell <NUM> is seated on the belt, the unit cell <NUM> moves by the belt. Here, a middle portion of the unit cell <NUM> is seated on the belt, and both sides facing each other with the middle portion therebetween are transferred while being mounted on the first rail 3a and the second rail 3b.

In the structure according to the related art, since each of the first rail 3a and the second rail 3b is made of a metal material and has a plate shape, the unit cell <NUM> has a problem that friction occurs at the contact portion of the first rail 3a and the second rail 3b during the transferring. The friction may wear a surface of the unit cell, and the unit cell may be damaged by the wear.

Particularly, in the unit cell <NUM>, the separator is often disposed on the surface of the conveyor, on which the unit cell <NUM> is seated. Thus, when the separator is manufactured as thin as possible so as to increase in capacity, as a length of the transfer device <NUM> becomes longer, the wear of the separator occurs by the friction to cause various problems (occurrence of short circuit, deterioration of yield, and the like).

Accordingly, a main object of the present invention is to provide a transfer device for a unit cell, in which a contact area between rails (first rail and second rail) and a unit cell is minimized to reduce frictional force generated therebetween, thereby solving the problem caused by friction that may occur during transferring of the unit cell.

The second rail has a length less than that of the first rail and, and when the unit cell is transferred, a tab guide through which the electrode tab protruding from each of the electrodes passes to prevent sagging of the electrode tab is disposed to continue along the traveling direction of the unit cell.

The present invention is defined by the subject matter of the appending claim <NUM>. Particular examples are given by the features of the dependent claims.

According to a preferred embodiment, the protrusion may protrude continuously along a longitudinal direction of the first rail and the second rail.

At least two or more protrusions may be disposed to be spaced apart from and parallel to each other on each of the first rail and the second rail.

The first rail and the second rail may be movable away from or close to the conveyor along a width direction perpendicular to the traveling direction of the unit cell.

Each of the first rail and the second rail may be movable to ascend or descend along a vertical direction.

In the tab guide, a lower arm disposed below the electrode tab and an upper arm disposed above the electrode tab may be disposed in parallel to each other to form a guide groove, into which the electrode tab enters to restrict vertical separation of the electrode tab while the unit cell is transferred, between the upper arm and the lower arm.

Each of the lower arm and the upper arm may have an inclined surface so that the guide groove increases in size at an end at which the electrode tab starts to enter.

A height of each of the lower arm and the upper arm, which is fixed in a vertical direction, may be adjustable so that a distance and height between the lower arm and the upper arm are adjustable.

In addition, it is preferable that the rail may be made of a synthetic resin to minimize an occurrence of friction. Particularly, it is preferable that the synthetic resin may comprise an acetal resin, and also, the tab guide may also be made of an acetal resin.

According to the present invention having the above configuration, since the protrusion protrudes from each of the first rail and the second rail, and the unit cell is in contact with only the protrusion of each of the first rail and the second rail during the traveling, the wear and damage due to the friction may be maximally suppressed or prevented to reduce the rate of the occurrence of the defects.

The second rail has the length less than that of the first rail, and when the unit cell is transferred, the tab guide through which the electrode tab passes to prevent the sagging from occurring is disposed along the traveling direction of the unit cell to prevent the sagging of the electrode tab from occurring.

At least two or more protrusions may be disposed to be spaced apart from each other on each of the first rail and the second rail, thereby distributing the load.

The first rail and the second rail may be configured to move away from or close to the conveyor along the width direction perpendicular to the traveling direction of the unit cell, and thus, the unit cells having various sizes may be transferred.

Since each of the first rail and the second rail is movable to ascend or descend in the vertical direction, the load of the unit cell, which is applied to the protrusion, may be adjusted.

The tab guide may guide the electrode tab having the various sizes and shapes because the distance and height between the lower arm and the upper arm are adjusted, and each of the lower arm and the upper arm may have the inclined surface to increase in size of the guide groove at the end at which the electrode tab starts to enter so that the electrode tab is smoothly guided between the lower arm and the upper arm without the impact or bending.

In addition, in the present invention, each of the rail and the tab guide may be made of the acetal resin having the low frictional force to minimize the wear of the unit cell.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

The present invention relates to a transfer device for a unit cell, which transfers unit cells, in which negative electrodes, separators, and positive electrodes are stacked by the predetermined number, from a starting position, at which the unit cells are seated, to the predetermined specific target position (e.g., the position at which the gripper stands by). Hereinafter, the transfer device for the unit cell according to embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

<FIG> is a perspective view of a transfer device for a unit cell according to a preferred embodiment of the present invention, and <FIG> is a plan view of the transfer device for the unit cell according to the preferred embodiment of the present invention.

Referring to <FIG> and <FIG>, the transfer device of the present invention comprises a conveyor <NUM> and first and second rails <NUM> and <NUM>, which are disposed at one side and the other side of the conveyor <NUM>, respectively.

The conveyor <NUM> is configured so that a belt continuously rotates along a longitudinal direction (traveling direction illustrated in <FIG>) by rotation of rollers (not shown), and when the unit cell <NUM> is seated on the belt, the seated unit cell <NUM> is transferred. That is, a length of each of the conveyor <NUM> and the first and second rails <NUM> and <NUM> is determined so that the unit cell <NUM> is transferred to a target point.

In addition, the first rail <NUM> is disposed at one side of the conveyor <NUM> so as to be parallel to the conveyor <NUM>, and the second rail <NUM> is disposed at the other side of the conveyor <NUM> with the conveyor <NUM> therebetween so as to be parallel to the conveyor <NUM>.

In addition, in the present invention, protrusions <NUM> and <NUM> protrude from a surface of each of the first rail <NUM> and the second rail <NUM> along the traveling direction of the unit cell <NUM>. Here, each of the first rail <NUM> and the second rail <NUM> has the same or almost similar length as the conveyor <NUM>, and each of the protrusions <NUM> and <NUM> protrudes in all sections in which the unit cell <NUM> travels on each of the first rail <NUM> and the second rail <NUM>.

When the unit cell <NUM> is seated on each of the protrusions <NUM> and <NUM>, each of the protrusions <NUM> and <NUM> protrudes to have a height and size at which a bottom surface of the unit cell <NUM> is not in contact with a remaining area expect for the protrusions.

Thus, while the unit cell <NUM> is transferred through the conveyor <NUM>, both ends of the unit cell <NUM> are supported by both the protrusions <NUM> and <NUM> and then are transferred. That is, while the unit cell <NUM> is transferred by the conveyor <NUM>, only the projections <NUM> and <NUM> are supported on the first rail <NUM> and the second rail <NUM>, respectively, and then are transferred.

It is preferable that the protrusions <NUM> and <NUM> protrude continuously along the longitudinal direction of the first rail <NUM> and the second rail <NUM> (continuously continuous along the traveling direction), but the protrusions <NUM> and <NUM> may be discontinuously formed so as not to be continuous at one or more points. Here, the non-continuous section may be determined according to the width of the unit cell. Furthermore, it is preferable that each of ends of the protrusions <NUM> and <NUM> is formed in a round shape having an appropriate size so that the unit cell <NUM> is smoothly transferred without scratches.

In addition, at least two or more protrusions <NUM> and <NUM> may be disposed to be spaced apart from and parallel to each other on each of the first rail <NUM> and the second rail <NUM>. In each of the first rail <NUM> and the second rail <NUM>, it is preferable that a gap between the protrusions adjacent to each other is maximally spaced apart from each other along the width direction to distribute a load of the unit cell <NUM>.

Furthermore, the first rail <NUM> and the second rail <NUM> may be configured to move away from or close to the conveyor <NUM> along the width direction perpendicular to the traveling direction of the unit cell <NUM>. Thus, when the unit cell <NUM> is seated as illustrated in <FIG>, the first rail <NUM> and the second rail <NUM> may be adjusted along the width direction according to the size of the unit cell <NUM>.

In addition, each of the first rail <NUM> and the second rail <NUM> is movable to ascend or descend in the vertical direction. Thus, since the distribution of the load of the unit cell <NUM>, which is applied to the conveyor <NUM> and the first and second rails <NUM> and <NUM>, is adjusted, the load applied to the first rail <NUM> and the second rail <NUM> may be reduced to minimize an occurrence of frictional force.

For reference, movement of each of the first rail <NUM> and the second rail <NUM> may be accomplished by known methods and combinations thereof, such as a combination of a motor and a link device or a combination of a pneumatic device and a gear device.

The transfer device for a unit cell, additionally comprises a tab guide <NUM> to prevent sagging of an electrode tab 4a from occurring.

As illustrated in <FIG>, a second rail <NUM> has a length less than that of the first rail <NUM>, and when the unit cell <NUM> is transferred, a tab guide <NUM> through which the electrode tab 4a passes to prevent sagging of the electrode tab 4a from occurring is disposed to continue along a traveling direction of the unit cell <NUM>.

<FIG> is a perspective view of the tab guide <NUM>, and <FIG> is a side view of the tab guide <NUM>. As illustrated in <FIG> and <FIG>, the tab guide <NUM> is configured by coupling a lower arm <NUM> to an upper arm <NUM>, and a guide groove is formed between the lower arm <NUM> and the upper arm <NUM> so that the electrode tab 4a enters to be slidable.

That is, the lower arm <NUM> is disposed under the electrode tab 4a, which is either a positive electrode tab protruding from a positive electrode provided in the unit cell <NUM> or a negative electrode tab protruding from a negative electrode provided in the unit cell <NUM>, and the upper arm <NUM> is spaced apart from the lower arm <NUM> in parallel to the lower arm <NUM> to form a guide groove <NUM> into which the electrode tab 4a enters while the unit cell <NUM> is transferred. According to the present invention, the tab guide <NUM> is disposed only on the second rail <NUM> as illustrated in <FIG>, however if the positive electrode tab and the negative electrode tab are unit cells protruding in directions opposite to each other, in a non-claimed alternative, the tab guide <NUM> may be installed on the first rail <NUM> as well as the second rail <NUM>. In such an alternative, each of the first rail <NUM> and the second rail <NUM> would be configured to have the same length as a conveyor <NUM>, which comprises a length connected to the tab guide <NUM>.

In addition, as illustrated in <FIG>, the upper arm <NUM> may be formed shorter along the traveling direction than the lower arm <NUM> and be configured so that the unit cell <NUM> does not interfere with the upper arm <NUM> at a point at which a gripper (not shown) grips the unit cell <NUM> when the unit cell <NUM> is picked up.

In addition, a height of each of the lower arm <NUM> and the upper arm <NUM>, which is fixed in a vertical direction, may be adjusted so that a distance and height between the lower arm <NUM> and the upper arm <NUM> are adjustable.

In addition, as illustrated more clearly in <FIG>, the lower arm <NUM> and the upper arm <NUM> may be configured to increase in area (increase in size of the guide groove) through which the electrode tab 4a is accessible from an end at which the electrode tab 4a starts to enter. Therefore, even if slight bending occurs in the electrode tab 4a, the electrode tab 4a may easily enter the guide groove <NUM> along inclined surfaces 41a and 42a.

In the present invention, it is preferable that the rails (the first rail and the second rail) is made of a synthetic resin to minimize generation of frictional force. Particularly, it is preferable that the synthetic resin material is made of an acetal resin, and also, the tab guide <NUM> is also made of an acetal resin.

In the present invention having the above configuration, protrusions <NUM> and <NUM> protrude from the first rail <NUM> and the second rail <NUM>, respectively, and since the unit cell <NUM> is in contact with only the protrusions <NUM> and <NUM> of the first and second rails <NUM> and <NUM> during the traveling, wear and damage due to friction may be maximally suppressed or prevented.

At least two or more protrusions <NUM> and <NUM> may be disposed to be spaced apart from each other on each of the first rail and the second rail, thereby distributing the load.

The first rail <NUM> and the second rail <NUM> may be configured to move away from or close to the conveyor <NUM> along a width direction perpendicular to the traveling direction of the unit cell <NUM>, thereby transferring unit cells having various sizes.

Since each of the first rail <NUM> and the second rail <NUM> is movable to ascend or descend in the vertical direction, the load of the unit cell, which is applied to the protrusions <NUM> and <NUM>, may be adjusted.

The second rail <NUM> has a length less than that of the first rail <NUM>, and when the unit cell <NUM> is transferred, a tab guide <NUM> through which the electrode tab 4a passes to prevent sagging of the electrode tab 4a from occurring is disposed to continue along a traveling direction of the unit cell <NUM>, thereby preventing the electrode tab from sagging.

The tab guide <NUM> may guide the electrode tabs 4a having various sizes and shapes because a distance and height between the lower arm <NUM> and the upper arm <NUM> are adjusted, and the lower arm <NUM> and the upper arm <NUM> may have inclined surfaces 41a and 42a to increase in size of the guide groove <NUM> at the end at which the electrode tab 4a starts to enter so that the electrode tab 4a is guided between the lower arm <NUM> and the upper arm <NUM> without an impact.

Claim 1:
A transfer device for a unit cell (<NUM>) , in which electrodes and separators are stacked by a predetermined number, the transfer device comprising:
a conveyor (<NUM>) configured to travel in one direction and transfer the seated unit cell (<NUM>) when the unit cell (<NUM>) is seated;
a first rail (<NUM>) disposed at one side of the conveyor (<NUM>) in parallel to the conveyor (<NUM>); and
a second rail (<NUM>) disposed at the other side of the conveyor (<NUM>) in parallel to the conveyor (<NUM>),
wherein a protrusion (<NUM>, <NUM>) protrudes from a surface of each of the first rail (<NUM>) and the second rail (<NUM>) along the traveling direction of the unit cell (<NUM>), and the unit cell (<NUM>) is supported by the protrusion (<NUM>, <NUM>) and transferred while being transferred through the conveyor (<NUM>),
wherein the second rail (<NUM>) has a length less than that of the first rail (<NUM>), and is continued along the traveling direction of the unit cell (<NUM>) by a tab guide (<NUM>), through which the electrode tab (4a) protruding from each of the electrodes passes when the unit cell (<NUM>) is transferred, in order to prevent sagging of the electrode tab (4a).