JP3948174B2 - Battery pack and power tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack in which a plurality of unit cells constituting an assembled battery are housed in a container, and in particular, can be stably charged while suppressing the temperature rise of each unit cell and variations in battery temperature. The present invention relates to a battery pack having a structure with excellent durability that can be sufficiently exerted, and an electric tool equipped with the battery pack as a drive source.
[0002]
[Prior art]
Recently, nickel-hydrogen secondary batteries have been used as driving sources for electric vehicles, electric assist bicycles, and electric tools. A battery used as this type of drive source is generally provided as a battery pack in which a battery pack in which a plurality of single cells are connected in series is housed in a container made of, for example, polycarbonate or ABS resin.
[0003]
By the way, in a conventional battery pack, a plurality of single cells are exclusively accommodated in a container in a close-packed state to increase the volumetric efficiency, and the overall shape is made compact. Incidentally, when a battery pack is formed by accommodating a plurality of unit cells having a cylindrical shape in a container, in general, for example, twelve unit cells 1 are arranged as shown in FIG. The peripheral surfaces are arranged in three rows in contact with each other so as to be accommodated in a rectangular container 2.
[0004]
[Problems to be solved by the invention]
However, in the battery pack having such a structure, there is a problem that temperature variation is likely to occur between the single cells 1 arranged along the wall surface of the container 2 and the single cells 1 arranged at the center thereof. is there. That is, the heat of the single cells 1 arranged along the wall surface of the container 2 is easily released through the wall surface of the container 2, but the heat of the single cells 1 arranged in the central part tends to be stored in the inside. It is in. Such variations in battery temperature cause variations in the battery characteristics (battery capacity) of the individual cells 1. If the battery pack is used in such a state, the life ends in the order from the unit cell 1 having a smaller battery capacity. For example, the unit cell 1 that has reached the end of its life has a reversal or cannot be recharged. This causes a problem that the performance as a battery pack is remarkably lowered, and the cycle life characteristics are deteriorated.
[0005]
When the single battery 1 is a secondary battery such as a nickel-hydrogen battery, a large amount of heat is generated during charging, and particularly when the battery 1 is charged in a short time with a large current, the heat generation phenomenon is significant. In addition, the nickel-hydrogen secondary battery has a lower charging efficiency and a lower battery capacity when the battery temperature increases. Furthermore, as the temperature rises, the hydrogen storage alloy constituting the negative electrode is easily corroded by the electrolytic solution, causing a problem that the hydrogen storage / release capability of the hydrogen storage alloy deteriorates. Therefore, it is important to prevent the temperature rise of the unit cell (nickel / hydrogen secondary battery) 1 accommodated in the container 2 especially during charging.
[0006]
In addition, a battery pack used as a drive source for an electric tool is generally required to have a robust structure against external impacts such as dropping because the electric tool itself is generally rough.
The present invention has been made in consideration of such circumstances, and the object thereof is to prevent a rise in the temperature of a plurality of single cells housed in a container and to suppress variations in the temperature of individual cells. An object of the present invention is to provide a battery pack capable of fully exhibiting performance. In particular, it is an object of the present invention to provide a battery pack that can be safely charged while effectively suppressing an increase in battery temperature during charging.
[0007]
Moreover, this invention is providing the electric tool provided with the battery pack of a robust and simple structure.
[0008]
[Means for Solving the Problems]
In order to achieve the above-described object, the battery pack according to the present invention contains a plurality of single cells made of, for example, nickel-hydrogen secondary batteries in a container,
A bowl-shaped container comprising a bottomed bowl sandwiched between an inner wall part and an outer wall part forming a pair of loops, and accommodating the plurality of single cells arranged in a loop between the inner wall part and the outer wall part. Provided with a terminal block that leads out the electrode leads of the assembled battery formed by the plurality of unit cells on the upper side of the plurality of unit cells accommodated side by side in the container, and covers the terminal block so as to cover the terminal unit. An opening for exposing the electrode lead so as to be externally connectable is provided at a portion of the lid that closes the upper opening of the lid facing the electrode lead.
[0009]
In a preferred aspect of the present invention, the bowl-shaped container is configured so that a plurality of unit cells each having a cylindrical shape are accommodated in a side-by-side loop with the peripheral surfaces thereof in contact with each other. The inner wall portion and the outer wall portion are formed at a height corresponding to the height of the unit cell. Furthermore, the terminal block is realized as a structure in which a pair of positive and negative electrode leads of a battery pack and a check terminal of the battery pack are arranged symmetrically (claim 3).
[0010]
In addition to the pair of positive and negative electrode leads of the assembled battery, the present invention is connected to one of the electrode leads through a temperature protection element that is used during charging and shuts off the charging path of the assembled battery in response to the battery temperature. A charging terminal, a temperature detection terminal connected to one of the electrode leads via a temperature sensing element for detecting the battery temperature, and further a resistance of the electrode lead according to the battery specification. Provided is a battery pack provided with three auxiliary terminals each including a battery type identification terminal connected to one of the terminals (claim 4).
[0011]
Preferably, the temperature protection element is provided at each of a plurality of locations along the arrangement direction of a plurality of single cells arranged in a loop, and the temperature protection elements are connected in series to connect the charging terminal and the one side. (5).
Furthermore, the present invention provides an electric tool equipped with the battery pack having the above structure as a drive source (claim 7).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, for a battery pack according to an embodiment of the present invention with reference to the drawings, for example, a battery pack in which 12 cylindrical nickel-hydrogen secondary batteries (unit cells 1) are connected in series and accommodated in a container 2. Will be described as an example.
FIG. 1 is an exploded perspective view showing the overall structure of a battery pack according to this embodiment. 1 is a 12 cylindrical nickel-hydrogen secondary battery as a unit cell, and 2 is a nickel-hydrogen secondary battery. It is a container for storing batteries (unit cells) 1 side by side. Further, 3 is a terminal block provided on the upper part of the nickel-hydrogen battery 1, and 4 is a lid that covers the terminal block 3 and closes the upper opening of the container 2.
[0013]
2 (a), 2 (b), and 2 (c) show the top structure, the side surface structure, and the longitudinal sectional structure of the battery pack shown in FIG. 1, respectively, and FIG. 3 shows an arrow A in FIG. 2 (a). A cross-sectional structure along -A is shown.
The container 2 is formed by injection molding of, for example, polycarbonate resin or ABS resin, and a pair of parallel wall portions and a pair of inner wall portions 21 looped in a so-called oval shape, which are connected between curved portions. It consists of a bottomed bowl-shaped body (a bowl-shaped container) that includes an outer wall part 22 and that connects the inner wall part 21 and the outer wall part 22 with a bottom part 23 to form a gallery-shaped battery storage space. The inner part of the bowl-shaped body forming the loop-shaped battery storage space thus looped, that is, the central part of the container 1 surrounded by the inner wall part 21 forms a hollow part that penetrates from the upper part to the bottom part. The height of the inner wall portion 21 and the outer wall portion 22 forming the battery storage space (depth of the ridge forming the battery storage space) is set slightly higher than the height (length) of the cylindrical unit cell 1. The width of the bottom 23 is set slightly wider than the diameter of the cylindrical unit cell 1. The cylindrical unit cell 1 is, for example, a 4 / 5A size, and has an outer diameter of 17 mm in diameter and 43 mm in height.
[0014]
Thus, the container 2 has twelve unit cells 1 arranged side by side in a loop in a row with the peripheral surfaces thereof in contact with each other in a bowl-shaped battery storage space composed of an inner wall portion 21, an outer wall portion 22, and a bottom portion 23. Arrange and store. Specifically, a circle is formed by arranging one unit cell 1 slightly eccentrically between the ends of two unit cell rows in which five unit cells 1 are arranged side by side in the longitudinal direction. The above-mentioned bowl-shaped battery storage space is set so as to form an arc-shaped short side portion and to arrange a total of twelve unit cells 1 in a loop shape in an oval shape.
[0015]
In addition, a notch 24 for fitting a stopper 5 described later is provided in a portion forming a wall surface in the longitudinal direction of the outer wall portion 22. Further, four screwing bosses 25 are erected along the outer wall portion 22 inside the bowl-shaped battery storage space. These screwing bosses 25 are provided by utilizing a space formed in the side portion of the cylindrical unit cell 1 that is housed with its peripheral surfaces being in contact with each other. It does not interfere with storage. Rather, these bosses 25 define the storage position of the unit cell 1 to prevent backlash.
[0016]
A flange 26 is provided at the upper end portion of the inner wall portion 21 so as to protrude outward from the bowl-shaped battery storage space, that is, toward the hollow portion formed in the central portion of the container 2. The flange 26 plays a role of supporting the terminal block 3 at an upper portion thereof, and also plays a role of fitting the center portion of the lid body 4 and supporting the center portion of the lid body 4 from below as described later. Bear.
[0017]
On the other hand, the plurality of single cells 1 housed in the bowl-shaped battery housing space of the container 2 described above are arranged in the form of a loop in an oval shape along the housing space as described above, and are connected in series by a lead body (not shown). Connected to. The upper end portions of the cell arrays arranged in a loop shape in an oval shape are covered with a cover body 11 made of, for example, an insulating material, so that the arrangement shape is stably maintained.
[0018]
Moreover, the terminal block 3 provided in the upper part of a cell row | line | column has the substantially U-shaped block body shape which consists of an insulating material, and the both sides along the longitudinal direction of the cell row | line | column arranged in the oval shape A pair of positive and negative electrode lead terminals 31, 32 is provided on the side, and three auxiliary terminals 33, 34, 35 are provided on the curved side portion along the short direction connecting the both side portions. The pair of positive and negative electrode lead terminals 31 and 32 are connected to electrode leads of a battery pack composed of a plurality of unit cells 1 connected in series. The three auxiliary terminals 33, 34, and 35 are used when charging the unit cell 1, and the auxiliary terminals 33, 34, and 35 include resistances built into the terminal block 3, The battery cells are connected to the electrode leads of the assembled battery through thermistors and thermostats arranged on the peripheral surface of the unit cells 1 arranged in a loop. The function of these auxiliary terminals 33, 34, and 35 will be described later with reference to FIG.
[0019]
Now, the lid 4 that covers the unit cell row accommodated in the container 2 and the terminal block 3 provided on the upper side and closes the upper opening of the container 2 is the upper end of the inner wall 21 and the outer wall 22 of the container 2. A substantially flat plate-like main body portion 41 that fits into the portion, and a projecting portion 42 that partially swells a portion of the main body portion 41 that faces the terminal block 3 and that forms an accommodation space for the terminal block 3 on the back side thereof. A shape having Five rectangular openings 43 (43a, 43b) that expose the electrode lead terminals 31, 32 and the three auxiliary terminals 33, 34, 35, respectively, so as to be externally connected, are provided on the side wall of the projecting portion 42. , To 43e). In addition, an opening 44 is provided at the center of the main body 41 and is located on the side of the projecting portion 42 and communicates with the cavity of the container 2. Furthermore, a substantially rectangular opening for fitting the stopper 5 is formed on the side portion in the longitudinal direction of the main body portion 41 in cooperation with the notch 24 provided in the outer wall portion 22 of the container 2 described above. A falling wall 45 is provided. When the lid 4 is put on the upper end opening of the container 2, the falling wall 45 fits into the upper part of the notch 24 and forms the opening between the notch 24.
[0020]
The lid 4 is fixed to the container 2 containing the unit cell 1 by screwing a screw 49 inserted from above the lid 4 through a through hole 47 provided in the main body 41 to the top of the boss 25. Is done by letting Further, a packing member (not shown) is appropriately interposed between the upper end portions of the inner wall portion 21 and the outer wall portion 22 of the container 2 and the lid body 4, and the battery storage space is closed in a sealed state.
[0021]
Here, the stopper 5 provided in the opening formed between the notch 24 and the falling wall 45 will be described. The stopper 5 includes a pressing portion 51 formed with a substantially quadrangular protrusion, and the pressing portion 51. The arm portion 52 extends from the side portion of the portion 51, and has a shape in which a hook-shaped hook 53 is formed at the tip of the arm portion 52. As shown in FIG. 3, the stopper 5 is fitted into the opening from the back side by causing the hook 53 to protrude from a hook hole 46 provided in the lid 4. Then, it is biased and supported toward the outside of the container 2 by a leaf spring 55 provided on the back surface thereof, and is biased inward by pressing with a finger or the like, so that the hook 53 is buried in the hook hole 46. Provided possible.
[0022]
The hook 53 is engaged with an engagement protrusion provided on the casing 70 of the electric power tool to which the battery pack is attached, thereby realizing the attachment of the battery pack to the electric power tool. That is, this battery pack has the lid 4 side, which is the upper part, as a mounting part to the lower part of the casing 70 of the electric tool, and by elastically biasing the hook 53 inward while abutting the engaging projection, The power tool is configured to be mounted with a so-called one-touch. At the time of removal, the hook 53 is forcibly biased by pushing the pressing portion 51 inward, and the engagement between the engagement projection provided on the housing 70 of the electric tool and the hook 53 is released. The battery pack can be removed toward the lower side of the casing 70.
[0023]
Here, the thermistor, the resistor, and the thermostat incorporated in the terminal block 3 described above will be described. These functional elements are provided to ensure safety when the battery pack is charged.
That is, as shown in the electrical configuration of the battery pack in FIG. 4, the plurality of single cells 1 are connected in series, and a pair of positive and negative electrode leads at both ends thereof are connected to the electrode lead terminals 31 and 32, respectively. Then, these electrode lead terminals (+, −) 31 and 32 are connected to a load such as an electric motor of the electric tool. Thus, the thermistor 81 accommodated in the container 2 is a temperature sensitive element that measures the surface temperature of the unit cell 1, and is interposed between the auxiliary terminal (Th) 33 and the electrode lead terminal 32. When charging the battery pack, the temperature of the unit cell 1 is monitored by monitoring the resistance value of the thermistor 81. The thermistor 81 is affixed to the peripheral surface of the unit cell 1 designated in advance.
[0024]
The resistor 82 interposed between the auxiliary terminal (ID) 34 and the electrode lead terminal 32 has a resistance value according to the specifications of the battery pack, and the resistance of the resistor 81 is charged when the battery pack is charged. By measuring the value, for example, the number of unit cells 1 connected in series, the current capacity, and the like are obtained as ID information. By controlling the charging of the battery pack in accordance with this ID information, overcharging or the like is prevented beforehand. That is, even if the external shape of the battery pack is the same, or even if the internal configuration is different, such as the number of unit cells 1 accommodated, the electronic specifications are required from the ID information, and in an optimal state It can be charged.
[0025]
Further, the auxiliary terminal 35 is used instead of the electrode lead terminal 32 when charging the battery pack, and charging is performed by supplying a charging current between the electrode lead terminal 31 and the auxiliary terminal 35. Thus, between the auxiliary terminal 35 and the electrode lead terminal 31, a temperature protection element, specifically, two thermostats 83 and 84, which shuts off the charging path for the battery pack in response to the battery temperature. Are interposed in series via the cell 1. These thermostats 83 and 84 are respectively affixed to the peripheral surface of the unit cell 1 that forms, for example, the two arc-shaped short sides described above along the arrangement direction of the plurality of unit cells 1 arranged in a loop. Provided. And since the unit cell 1 is provided in a loop shape, even if a difference occurs in the battery temperature, the thermostats 83 and 84 are operated as the temperature of any unit cell 1 rises. And has a function of blocking the charging path by itself.
[0026]
The charging device connected to the terminal block 3 and charging the battery pack monitors the charging state of the unit cell 1 (battery pack) from the auxiliary terminals 33, 34, and 35, and determines the charging current and charging time. By controlling, the battery pack is stably and efficiently charged. The above-described thermostats 83 and 84, when charging the battery pack under such charge control, when the battery temperature rises, by themselves blocking the charging path, Battery pack).
[0027]
Thus, according to the battery pack configured as described above, the plurality of single cells 1 are accommodated in a loop shape arranged side by side between the inner wall portion 21 and the outer wall portion 22 of the container 2 having a loop-shaped corridor shape. Therefore, the heat generated in each unit cell 1 is efficiently released through the inner wall portion 21 and the outer wall portion 22. And since the outer side of the inner wall part 21 of the center part of the container 2 becomes the cavity part which penetrates this container 2 up and down, the big heat dissipation effect of the single cell 1 through this cavity part can be anticipated. In particular, since the plurality of unit cells 1 are arranged in a line in a loop shape, the heat radiation effect on each unit cell 1 is made substantially constant as compared with the conventional unit cell arrangement structure shown in FIG. Can be aligned. Therefore, it is possible to suppress the temperature variation of each unit cell 1 while effectively preventing the temperature increase of the plurality of unit cells 1, and thus to fully demonstrate the battery performance of each unit cell 1. Battery performance as a battery pack can be improved.
[0028]
In addition, since the terminal block 3 is provided on the upper part of the unit cells 1 accommodated in the container 2 and arranged in a loop shape, and the electrode leads thereof are led out, this corresponds to the fact that the plurality of unit cells 1 are arranged in a loop shape. As a result, the lengths of the pair of electrode leads can be made uniform. Moreover, the length of the electrode lead itself can be shortened by providing the terminal blocks 3 at positions above both ends of the unit cells 1 connected in series as the assembled battery. Therefore, such effects as the resistance loss through the electrode lead can be minimized are exhibited. Furthermore, if the electrode lead is arranged along the inner wall portion 21, it becomes possible to effectively protect the electrode lead from an external impact applied to the container 2, so that the mechanical and structural stability is also improved. It can be sufficiently increased.
[0029]
Further, according to this battery pack, as described above, the auxiliary terminals 33, 34, and 35 connected via the thermistor 81, the resistor 82, and the thermostats 83 and 84 are provided. It is possible to recognize the specification of the battery pack via 35 and to control the charging while monitoring the battery temperature, so that the charging can be performed safely while preventing the battery temperature from rising. Furthermore, even when the charging control is not in time when the battery temperature rises, one of the thermostats 83 and 84 provided at a plurality of locations along the unit cells 1 arranged in a loop shape is sensitive to the battery temperature. Therefore, double safety measures can be taken.
[0030]
Further, according to the battery pack having the above-described structure, the lid 4 side is mounted on the casing 70 such as an electric tool, and the container 2 is mounted on the casing 70 with the lid 4 interposed therebetween. Accordingly, the lid 4 cannot be removed from the container 2 unless the battery pack is removed from the housing 70. Therefore, there is no problem that the lid 4 is unintentionally detached during use of the power tool. Further, the protruding portion 42 of the lid body 4 that protrudes by forming the accommodation space of the terminal block 3 on the back side thereof is covered with the casing 70 while being attached to the casing 70, so The battery pack has a so-called external shape with no protrusion. Therefore, if the outer peripheral surface of the container 2, especially the corner portion of the outer wall portion 22 and the boundary portion with the bottom portion 23, are respectively curved, the overall shape is smooth regardless of the presence of the protruding portion 42 in the lid portion 4. It becomes possible to improve the handling property.
[0031]
Further, as the projecting portion 42, the terminal block 3 is accommodated on the back side, and the electrode lead terminals 31, 32 and the auxiliary terminals 33, 34, 35 are exposed on the side wall surfaces so as to be externally connectable. Therefore, it is not necessary to raise the height so much. Therefore, it is easy to keep the protrusion height of the protrusion 42 in the lid 4 low, and the overall shape can be made compact. Moreover, it becomes possible to make it a structure strong against an external impact.
[0032]
In addition, in an electric tool equipped with a battery pack having such a structure, for example, the built-in fan is driven using the rotational force of the electric motor, and air is passed through the inside of the electric motor through the cavity of the container. By doing so, it is possible to cool the electric motor of the electric tool while cooling the battery pack itself by this air flow, and it is possible to achieve an effect that the cooling effect can be enhanced. Further, since the container 1 itself has a rounded appearance as a whole, its corners and the like are not easily caught on clothes and the like during work using the electric power tool, and the handleability is good. Moreover, since there are no corners, local stress concentration can be reduced even when an impact due to dropping or the like is applied, and a robust structure can be obtained.
[0033]
As the container 2, for example, as shown in FIGS. 2 (c) and 3, a predetermined taper is provided so that the inner wall 21 and the outer wall 22 are widened toward the upper end opening. If the shape is adopted, it is easy to remove the mold at the time of injection molding, and a bowl-like body having a depth corresponding to the height of the unit cell 1 can be easily realized. In addition, since the position of each unit cell 1 accommodated in the rod body is regulated by the boss 25 or the like, rattling of each unit cell 1 can be effectively suppressed, and the accommodation state of the unit cell 1 can be stabilized while having a simple structure. It can be maintained at a high level, and the strength can be improved.
[0034]
The present invention is not limited to the embodiment described above. For example, here, a battery pack configured by housing 12 unit cells 1 has been described, but the number of the battery packs may be determined according to specifications. It is of course possible to realize a battery pack in which a plurality of single cells 1 are connected in parallel as appropriate to increase the current capacity. Further, more temperature protection elements (thermostats) may be provided along the unit cells 1 arranged in a loop. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.
[0035]
【The invention's effect】
As described above, according to the present invention, a battery capable of sufficiently exhibiting its battery performance while suppressing a temperature rise and a temperature variation of each single battery while housing a plurality of single batteries structurally and stably. Pack can be offered. In addition, the wiring structure of the electrode leads can be simplified by incorporating the terminal block into the upper part of the unit cell. Further, there is an advantage that the charging of the battery pack can be controlled with good safety while monitoring the charging state, particularly the battery temperature, via the auxiliary terminal. Furthermore, since a plurality of single cells can be stably held, it is possible to realize a battery pack having a structure excellent in strength against external impacts and the like, and to provide an easy-to-use electric tool. Can be played.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an overall structure of a battery pack according to an embodiment of the present invention.
2 is a diagram showing a top structure, a side structure, and a longitudinal sectional structure of the battery pack shown in FIG. 1, respectively.
3 is a view showing a cross-sectional structure of the battery pack shown in FIG. 1 along the line AA in FIG. 2 (a).
4 is a diagram showing an electrical configuration of the battery pack shown in FIG. 1. FIG.
FIG. 5 is a diagram showing an arrangement structure of single cells in a conventional general battery pack.
[Explanation of symbols]
1 cell 2 container (container)
3 Terminal block 4 Lid 5 Stopper body 21 Inner wall portion 22 Outer wall portion 23 Bottom portion 31, 32 Electrode lead terminals 33, 34, 35 Auxiliary terminal 41 Main portion 42 Protruding portion 43 Opening portion 70 Power tool housing 81 Thermistor (temperature sensitive) element)
82 Resistance (ID information)
83,84 Thermostat (temperature protection element)

Claims (7)

A plurality of single cells constituting an assembled battery;
A bowl-shaped container comprising a bottomed bowl-like body sandwiched between an inner wall part and an outer wall part forming a pair of loops, and accommodating the plurality of single cells arranged in a loop between the inner wall part and the outer wall part; ,
A terminal block that is provided on top of a plurality of single cells housed side by side in this bowl-shaped container and leads out the electrode leads of the assembled battery;
A lid that covers the terminal block and closes the upper opening of the bowl-shaped container;
A battery pack comprising: an opening that is opened at a portion of the lid facing the electrode lead and exposes the electrode lead to be externally connectable. The bowl-shaped container accommodates a plurality of unit cells each having a cylindrical shape, arranged in a side-by-side and loop form with their peripheral surfaces in contact with each other, and the inner wall portion and the outer wall portion of the bowl-shaped body The battery pack according to claim 1, wherein the battery pack has a height corresponding to a height of the unit cell. The battery pack according to claim 1, wherein the terminal block has a structure in which a pair of positive and negative electrode lead terminals connected to electrode leads of the assembled battery and auxiliary terminals of the assembled battery are arranged. The auxiliary terminal provided on the terminal block is used when charging the assembled battery,
A charging terminal connected to one of the electrode leads via a temperature protection element that cuts off a charging path of the assembled battery in response to the battery temperature, and one of the electrode leads via a temperature sensitive element that detects the battery temperature 2. The temperature detection terminal connected to the battery and a battery type identification terminal connected to one of the electrode leads through a resistor having a resistance value according to battery specifications. Battery pack. The temperature protection element is provided at each of a plurality of locations along the arrangement direction of the plurality of single cells arranged in a loop, and is connected in series between the charging terminal and the one electrode lead. The battery pack according to claim 4, wherein the battery pack is interposed. The battery pack according to claim 1, wherein the single battery is a nickel-hydrogen secondary battery. An electric tool comprising the battery pack according to claim 1 as a drive source.

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