JP2017091963A - Battery pack for electrically operated vehicle and electrically operated vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that a battery pack having a structure suitable for an electrically operated vehicle working under an ambient environment, where foreign matters such as grasses or straws are floating, is desired.SOLUTION: A battery pack 6 to be mounted on an electrically operated vehicle includes a sealed battery case 60 consisting of a front case 61 and a rear case 62, a horizontal partition wall 63 for sectioning the inside of the case 61 vertically into a first space S1 and a second space S2, and sectioning the inside of the case 62 vertically into a third space S3 and a fourth space S4, an electrical unit 68 to be housed in one of the first, second, third and fourth spaces, and a battery module 6A to be housed in each of the remaining spaces.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery pack for an electric work vehicle that is operated by an electric motor, and an electric work vehicle equipped with the battery pack.

  In the field of passenger cars, electric vehicles that run with the rotational force of an electric motor have begun to spread. At that time, a battery is mounted on the vehicle as a power source for the electric motor. In order to maintain the performance of the battery, it is necessary to keep the battery temperature at an appropriate temperature. Therefore, the battery is often provided with a cooling structure. For example, in a vehicle battery pack according to Patent Document 1, a battery cell group including a plurality of battery cells and a cooling fan for flowing air to the battery cell group are housed in a case. The case is further formed with a suction port for introducing air into the case from the outside and a discharge port for discharging the air to the outside of the case. The air flow generated by the rotational drive of the cooling fan passes through the gap between the battery cells and the intake passage extending to the bottom space between the inner bottom surface of the case and the bottom surface of the battery cell group. That is, the cooling air introduced from the outside of the vehicle into the case through the intake port is discharged from the discharge port to the outside of the case via the intake passage, the bottom space, and the gap between the batteries. Furthermore, a plurality of radiating fins projecting downward are provided on the lower surface of the case.

  However, in working vehicles that run while working, such as mowers, rice transplanters, tractors, etc., the ambient environment during work traveling is worse than the surrounding environment such as automobiles, and cooling air is taken in from the surroundings. The cooling air is likely to be mixed with dust such as cut grass and firewood, causing a problem such as clogging of the cooling air passage.

Japanese Patent Application Laid-Open No. 2014-0751181

  In view of the above circumstances, there is a demand for a battery pack having a structure suitable for an electric work vehicle that works and travels in an ambient environment where foreign objects such as grass and straw are floating. At that time, when such a battery pack includes a plurality of battery modules, it is also important to make the temperature of each battery module as uniform as possible.

  A battery pack for an electric working vehicle according to the present invention divides a sealed battery case composed of a front case portion and a rear case portion into a first space and a second space in the vertical direction. And a horizontal partition wall that divides the interior of the rear case portion into a third space and a fourth space in the up-down direction, of the first space, the second space, the third space, and the fourth space. A battery electrical unit that is housed in one space; and a battery module that is housed in each of the remaining spaces of the first space, the second space, the third space, and the fourth space. .

The above-mentioned “sealing” does not mean that the internal space of the battery case is maintained in a completely airtight state, but the flow of the external air to the internal space is suppressed, and the external air temperature and the internal space temperature are simple. Is used as a term that has a broad meaning including a loose airtight state that is not balanced.
In addition, the terms “first space”, “second space”, “third space”, and “fourth space” do not limit the number of divided spaces to four, and the battery case further includes a fifth space, a sixth space,. It may be divided into

  In this configuration, the inside of the sealed battery case is divided into a plurality of spaces by a horizontal partition wall, the battery electrical unit is disposed in one space, and the battery electrical unit is disposed in the remaining space. . Thereby, dust, such as cut grass and a hail, does not penetrate | invade into the inside of a battery case substantially. In addition, since the inside of the battery case is divided vertically by the horizontal partition wall, it is possible to prevent the heat released from the plurality of battery modules from being concentrated on the ceiling area of the battery case.

  As a particularly preferred embodiment, a circulation fan is provided that creates a longitudinal airflow that circulates through the first space, the second space, the third space, and the fourth space. In this configuration, a plurality of battery modules and a circulation fan are hermetically housed in a single battery case, and the external air circulation by the circulation fan and the suppression of the ingress of outside air by sealing the battery case While the entry of foreign matter from the inside is suppressed, the temperature in the case space is made uniform. At that time, when the electrical unit and the battery module are arranged so that the cooling air generated by the circulation fan passes through the electrical unit and each battery module in order, the temperature distribution of each battery module is made as uniform as possible. . As a result, the temperature distribution of the battery modules is easily made uniform, and each battery module operates electrically efficiently.

  The right of the present invention also extends to an electric work vehicle equipped with the above-described battery pack.

It is the perspective view partly fractured | ruptured which shows the basic structure of a battery pack. 4 is a side view schematically showing a basic example of mounting a battery pack on an electric work vehicle. It is a plane which shows typically an example of basic mounting to an electric work vehicle of a battery pack. It is a side view of the riding type electric mower which is one of the embodiments of the electric work vehicle. It is a top view of a riding type electric mower. It is a perspective view which shows a vehicle body frame, a battery pack, and the drive mechanism of a rear-wheel unit. It is a perspective view of a battery pack. It is a cross-sectional view of a battery pack. It is an exploded view of a battery case.

  Before describing a specific embodiment of a battery pack related to the present invention, the basic structure of a battery pack mounted on an electric work vehicle will be described with reference to FIG. 2 and FIG. A basic arrangement of the battery pack when such a battery pack is mounted on an electric work vehicle will be described. In this specification, the longitudinal direction of the vehicle body is the direction of the vehicle body central axis (also referred to as the vehicle body longitudinal axis) that extends in the horizontal direction along the traveling direction of the vehicle body on which the battery pack is mounted. (Also referred to as a direction) is a direction extending in the horizontal direction perpendicular to the center axis of the vehicle body. “Front (front)” means the forward side in the vehicle longitudinal direction, and “rear (back)” means the backward side in the vehicle longitudinal direction. “Left (left side)” means left when facing the vehicle body advance direction, and “Right (right side)” means right when facing the vehicle body advance direction.

  The battery pack 6 shown in FIG. 1 includes a battery case 60, a horizontal partition wall 63, a battery electrical unit 68 (abbreviated simply as an electrical unit 68), and a plurality of battery modules 6A. The battery case 60 is a sealed case including a front case portion 61 and a rear case portion 62. In FIG. 1, facing the drawing, the left side is defined as the front side (front) and the right side is defined as the rear side (rear). The front case part 61 and the rear case part 62 are not separate members, but are the names of the battery case 60 when considering the front part and the rear part separately. The front case part 61 and the rear case part As a result, the battery case 60 is formed. In the example shown in FIG. 1, the transition region from the front case portion 61 to the rear case portion 62 is inclined upward. Thereby, the rear case part 62 is shifted upward in the vertical direction with respect to the front case part 61, and the battery case 60 is a solid body having an upper step in the middle. This step is required due to restrictions on the usage pattern, and may have a lower step or no step.

  The horizontal partition wall 63 is a plate member provided so as to bisect the interior of the battery case 60 vertically. By the horizontal partition wall 63, the inside of the front case portion 61 is divided into a first space S1 and a second space S2 in the vertical direction, and the inside of the rear case portion is divided into the third space S3 and the fourth space S4 in the vertical direction. It is divided into. The first space S1 and the third space S3 communicate with each other and form an upper space of the battery case. Similarly, the second space S2 and the fourth space S4 communicate with each other and form a lower space of the battery case. The front end of the horizontal partition wall 63 has a gap 63 a that allows air flow between the first space S <b> 1 and the second space S <b> 2 with the front wall surface of the horizontal partition wall 63. A rear end of the horizontal partition wall 63 is provided with a gap 63b that allows air flow between the third space S3 and the fourth space S4 with the rear wall surface of the horizontal partition wall 63. As a result, an air circulation path that returns from the first space S1 to the first space S1 through the second space S2, the fourth space S4, and the third space S3 is formed inside the battery case 60.

  In the example of FIG. 1, the electrical unit 68 is disposed in the first space S1, and one battery module 6A is disposed in each of the second space S2, the third space S3, and the fourth space S4. The battery module 6A is composed of a large number of battery cells 6a. Furthermore, a circulation fan 49 is arranged in the first space S1 so as to send air from the first space S1 to the third space S3. Thereby, the flow path of the circulating air through which air passes in order of 1st space S1- 3rd space S3- 4th space S4- 2nd space S2- 1st space S1 is created. This flow of circulating air not only cools the electrical unit 68 but also makes the temperatures of the second space S2, the third space S3, and the fourth space S4 in which the battery modules 6A are disposed uniform. This prevents malfunction of the battery module 6A due to uneven temperature distribution.

  For maintenance of the electrical unit 68 and each battery module 6A, the battery case 60 is configured to be at least partially removable, or an opening that is closed by a lid is formed.

  2 and 3 are side views for explaining a basic example of mounting the battery pack 6 shown in FIG. 1 on the electric work vehicle. This electric work vehicle includes a left frame 21 and a right frame 22 that extend in the longitudinal direction of the vehicle body at intervals in the transverse direction of the vehicle body, and a vehicle body that includes at least one cross beam 23 that connects the left frame 21 and the right frame 22. A frame 20 is provided. The left front wheel 11L and the right front wheel 11R constituting the front wheel unit are disposed in the front portion of the body frame 20. The left rear wheel 12L and the right rear wheel 12R constituting the rear wheel unit are disposed on the rear side from the center of the body frame 20. In the following, unless it is particularly necessary to distinguish between the left front wheel 11L and the right front wheel 11R, the term front wheel unit 11 is used as a generic term, and the left rear wheel 12L and the right rear wheel 12R are generically used as a rear wheel. The term unit 12 is used. The rear axle center Pr extends in the vehicle body transverse direction.

  The battery pack 6 is disposed in the rear half region of the vehicle body frame 20 between the left frame 21 and the right frame 22, and when viewed from the side, the front end of the battery pack 6 is in front of the rear axle Pr and substantially the rear wheel. It is located near the front end of the unit 12. The rear end of the battery pack 6 is located substantially at the rear end of the vehicle body frame 20. As apparent from FIG. 3, the battery pack 6 has a width that fits almost between the left frame 21 and the right frame 22, and extends in the longitudinal direction of the vehicle body with an equal width. As is clear from FIG. 2, the front half of the battery pack 6 enters the axle space of the rear wheel unit 12. A particularly preferable arrangement of the battery pack 6 is that the center of gravity of the battery pack 6 is on the center line in the longitudinal direction of the vehicle body and within the distance from the rear axle to the rear wheel 12 in the longitudinal direction of the vehicle body. Thereby, the weight of the battery pack 6 contributes to the stability of the vehicle body.

  Further, the battery pack 6 has a shape in which the rear case portion 62 is displaced upward in the vertical direction with respect to the front case portion 61. Therefore, the ground height Hb of the rear case portion 62 of the battery pack 6 is higher than the ground height Hf of the front case portion 61 of the battery pack 6. In the example shown in FIG. 2, the ground height Hf of the front case portion 61 is substantially the same as the ground height at the lower end of the rear axle case 31 of the rear wheel unit 12. The ground height Hb of the rear case portion 62 of the battery pack 6 is higher than the ground height of the rear axle case 31 and is substantially the same as the ground height of the rear axle center Pr. The minimum ground height of the vehicle body frame 20 at the portion supporting the battery pack 6 is substantially equal to the minimum ground height of the battery pack 6. Since the ground height Hf of the front case portion 61 is set low, the center of gravity of the battery pack 6 is lowered, and the running stability is improved. In addition, since the ground height Hb of the rear case portion 62 is set to be high, the possibility that the rear end of the battery pack 6 or the vehicle body frame 20 contacts the ground or stone is low when traveling uphill or traveling on a rough road. .

  The left motor 4L that transmits rotational power to the left rear wheel 12L is disposed around the left rear wheel 12L near the front case portion 61 of the battery pack. The right motor 4R that transmits rotational power to the right rear wheel 12R is disposed around the right rear wheel 12R in the vicinity of the rear case portion 62. The left motor 4L and the right rear wheel 12R are disposed at symmetrical positions. In order to create an arrangement space for the left motor 4L and the right motor 4R, a portion covering the first space S1 of the front case portion 61 may be recessed. A driver seat 16 is disposed above the left motor 4L and the right motor, and space is effectively used.

  In the battery pack 6 illustrated in FIG. 1, the front rectangular parallelepiped portion 6 </ b> F of the battery pack 6 has a convex shape extending in the front-rear direction of the vehicle body in a form in which the upper right portion and the upper left portion are omitted in order to effectively use the space. A central portion 6Fc is formed. For this reason, spaces are created on the left and right of the central portion 6Fc. The left motor 4L enters the space on the left side of the central portion 6Fc of the front rectangular parallelepiped portion 6F, and the right motor 4R enters the space on the right side of the central portion 6Fc.

  Next, one specific embodiment of an electric work vehicle on which a battery pack is mounted will be described with reference to the drawings. FIG. 4 is a side view of a riding electric mower as an example of an electric work vehicle, and FIG. 5 is a plan view of the riding electric mower.

  As shown in FIGS. 4 and 5, the riding electric mower (hereinafter simply referred to as a mower) includes a vehicle body 10, and the vehicle body 10 includes a caster type including a left front wheel 11L and a right front wheel 11R. The front wheel unit 11 and a rear wheel unit 12 including a left rear wheel 12L and a right rear wheel 12R that are rotationally driven are supported on the ground. The vehicle body 10 has a vehicle body frame 20 as a base frame. The body frame 20 includes a left frame 21, a right frame 22, and a cross beam 23 that connects the left frame 21 and the right frame 22. A mower unit 13 is suspended from the vehicle body frame 20 via a link mechanism 14 between the front wheel unit 11 and the rear wheel unit 12. The mower unit 13 includes a blade transmission mechanism 131 and a blade 132 that is rotated by the blade transmission mechanism 131. A driver's seat 16 is disposed in the center region of the vehicle body 10 in the longitudinal direction of the vehicle body. The basic structure of the battery pack 6 and the basic arrangement in the vehicle body frame 20 adopt the contents described with reference to FIGS. 1 and 2.

  FIG. 6 is a perspective view showing the vehicle body frame 20, the battery pack 6, and the drive mechanism of the rear wheel unit 12. The drive mechanism that supplies rotational power to the rear wheel unit 12 includes a motor 4, a transmission case 30, and a rear axle case 31. As shown in FIG. 6, the left frame 21 and the right frame 22 branch up and down from the middle region and are connected again in the rear region. That is, the left frame 21 is a rear half region and includes an upper frame portion 21a and a lower frame portion 21b. Similarly, the right frame 22 is a rear half region, and includes an upper frame portion 22a and a lower frame portion 22b. In a side view, the left transmission case 30L is disposed in the region between the upper frame portion 21a and the lower frame portion 21b of the left frame 21, and in the region between the upper frame portion 22a and the lower frame portion 22b of the right frame 22. A right transmission case 30R is disposed. A left rear axle case 31L is connected to the left transmission case 30L, and the left rear wheel 12L is supported by the left rear axle case 31L. A right rear axle case 31R is connected to the right transmission case 30R, and the right rear wheel 12R is supported by the right rear axle case 31R. The left rear axle case 31L is a cylindrical body that supports and supports the left rear axle 41 of the left rear wheel 12L, and the outer shape thereof is a truncated cone shape. Similarly, the right rear axle case 31R is a cylindrical body that supports and supports the right rear axle 42 of the right rear wheel 12R, and its outer shape is a truncated cone shape. The battery pack 6 is such that the center of gravity of the battery pack 6 is located substantially on the center line in the longitudinal direction of the vehicle body in a plan view and is within the length of the rear wheel radius on the front side and the rear side from the rear axle axis Pr. Has been placed.

  The left transmission case 30L is a hollow body that extends from the left rear axle case 31L forward in the vehicle longitudinal direction so as to be orthogonal to the rear axle Pr that is also the center axis of the left rear axle case 31L, and has a gear transmission mechanism therein. The left transmission consisting of A mounting surface for the left motor 4L is formed on the power input portion 32f of the left transmission case 30L. Similarly, it is a hollow body that extends forward from the right rear axle case 31R in the front-rear direction of the vehicle body so as to be orthogonal to the rear axle center Pr that is also the center axis of the right rear axle case 31R. The transmission is built in. The gear transmission mechanism generally decelerates input power, but may be increased or may not increase or decrease. A mounting surface for the right motor 4R is formed on the power input portion 32f of the right transmission. In this embodiment, the left transmission case 30L and the left rear axle case 31L are integrally configured, and the right transmission case 30R and the right rear axle case 31R are integrally configured. As the left transmission and the right transmission, a chain electric mechanism, a transmission shaft mechanism, or the like may be employed instead of the gear transmission mechanism.

  The speed change operation for the left motor 4L and the right motor 4R is performed by a pair of left and right speed change levers 18 (see FIGS. 4 and 5) disposed on both sides of the driver seat 16. When the speed change lever 18 is held in the front-rear neutral position, the corresponding motor 4 is stopped, and by operating the speed change lever 18 forward from the neutral position, the corresponding motor 4 is driven to rotate forward to realize forward shift, and to the rear. By operating, the corresponding motor 4 is driven backward to realize reverse gear shifting. The left motor 4L and the right motor 4R are independently controlled at variable speeds by independent operation of the pair of left and right transmission levers 18 respectively. For example, when the pair of left and right shift levers 18 are operated from the neutral position in the forward direction with substantially the same operation amount, both the left rear wheel 12L and the right rear wheel 12R are driven at substantially the same speed, and the vehicle body 10 advances straight forward. . When the pair of left and right speed change levers 18 are operated from the neutral position in the rearward direction with substantially the same operation amount, the left rear wheel 12L and the right rear wheel 12R are driven in the reverse direction at substantially the same speed, and the vehicle body 10 travels straight and reverse. . Further, when the pair of left and right speed change levers 18 are operated with different operation amounts, the left rear wheel 12L and the right rear wheel 12R are driven at different speeds, and the vehicle body 10 turns. At that time, one of the left rear wheel 12L and the right rear wheel 12R is turned to a low speed close to zero speed, and the other is operated at a high speed to the forward side or the reverse side, thereby making a small turn. Further, by driving the left rear wheel 12L and the right rear wheel 12R in opposite directions, the vehicle body 10 can be spin-turned with the substantially central portion of the rear wheel unit 12 as the turning center.

  Hereinafter, the battery pack 6 will be described with reference to FIGS. 6, 7, 8, and 9. The battery pack 6 includes a plurality of battery modules 6 </ b> A housed in a battery case 60. In the description of the basic configuration of the battery pack 6 using FIGS. 1, 2, and 3, the battery pack 6 is handled as an integrated battery case 60 and battery module 6 </ b> A. The front half of the battery pack 6 was defined as the front rectangular parallelepiped portion 6F, and the rear half of the battery pack 6 was defined as the rear rectangular parallelepiped portion 6B. Further, a convex central portion 6Fc is formed in the upper half of the front rectangular parallelepiped portion 6F, the left motor 4L is disposed in the left space of the central portion 6Fc, and the right motor 4R is disposed in the right space of the central portion 6Fc. It has entered. Such an arrangement structure is also adopted in this embodiment. However, in the description of the battery pack 6 here, the structure of the battery case 60 and the battery module 6A, which are originally separate bodies, will be described separately.

  The battery case 60 is a molded product that is split into two vertically and includes an upper case 60a and a lower case 60b. However, in order to facilitate the description of the internal structure, the battery case 60 will be described by being divided into a front case portion 61 and a rear case portion 62.

  The front case part 61 is a solid body in which a convex center part 611 is formed at the upper part by denting the upper left part and the upper right part from a rectangular parallelepiped. In other words, the length in the transverse direction of the fuselage is shortened so that a motor storage space into which the left motor 4L and the right motor 4R enter is formed on both sides of the central portion 611 in the transverse direction of the fuselage. The rear case part 62 is a rectangular parallelepiped connected to the front case part 61 in the front-rear direction. The front case portion 61 and the rear case portion 62 are connected in a posture in which the rear case portion 62 is displaced upward, and the battery case 60 has a three-dimensional shape having a vertical difference between the front side and the rear side. The central portion 611 has an enlarged portion 612 that is enlarged leftward and rightward and upward in a connection region between the front case portion 61 and the rear case portion 62, and the internal space of the enlarged portion 612 is expanded.

  The rear case part 62 has a rectangular parallelepiped shape having the same lateral width (length in the vehicle body transverse direction) as the front case part 61. The rear case portion 62 is displaced upward with respect to the front case portion 61, and thus the battery case 60 has a stepped cubic shape having a step between the front case portion 61 and the rear case portion 62. .

  As shown in FIGS. 8 and 9, the battery case 60 divided into an upper case 60 a and a lower case 60 b has a horizontal partition that divides the inside vertically into a front case portion 61 and a rear case portion 62. A wall 63 is provided. By the horizontal partition wall 63, the inside of the front case portion 61 is divided into an upper first space S1 and a lower second space S2, and the interior of the rear case portion 62 is separated from the upper third space S3 and the lower side space S2. It is divided into the fourth space S4. The horizontal partition wall 63 is a plate material, and is formed so as to have an upper and lower step similar to that of the battery case 60 through bending, and the second space S2, the third space S3, and the fourth space S4 have substantially the same shape and volume. It has become. The first space S1 is smaller in width and height than other spaces. A vertical partition wall 64 is provided between the first space S1 and the third space S3.

  Battery modules 6A having the same specifications are accommodated in the second space S2, the third space S3, and the fourth space S4. As shown in FIG. 9, the battery module 6 </ b> A is a rectangular parallelepiped having a lower height than the vertical dimension and the horizontal dimension. A large number of battery cells 6a are accommodated in the battery module 6A.

  In the first space S1, an electrical unit 68 composed of a relay, a fuse, or the like provided on a power line connecting the battery module 6A and the outside is housed. The vertical partition wall 64 is equipped with a circulation fan 69 that sucks air from the first space S1 and sends it to the third space S3. The electrical system of the circulation fan 69 is incorporated in the electrical unit 68. The horizontal partition wall 63 has a front end gap G1 formed between the front end 63a and the front case portion 61, and a rear end gap G2 formed between the rear end 63b and the rear case portion 62. Furthermore, the battery case 60 has a sealed structure to such an extent that grass and dust do not enter the internal space from the outside, or air flow between the internal space and the outside is suppressed. As a result, the circulating air flow exits from the circulation fan 69, passes through the third space S3, the fourth space S4, and the second space S2 to reach the first space S1 and returns to the circulation fan 69. A path (indicated by an arrow in FIG. 8) is formed. The temperature of the four spaces of the battery case 60 is equalized by the circulating air flowing through the circulating air flow path. Further, the electrical unit 68 is cooled by such circulating air. In order to enhance this cooling effect, fins 60 f are formed on the wall surface of the battery case 60, although only partially illustrated. The fins 60f can be formed on the inner wall surface, the outer wall surface, or both of the battery case 60.

  An opening for maintenance and inspection of the electrical unit 68 is provided in the upper wall of the front case portion 61 and is normally closed by a lid 613.

  As shown in FIG. 4, in this embodiment, a work motor 4W for supplying power to the mower unit 13 as a work device is disposed at the rear of the mower unit 13, and the power from the work motor 4W is transmitted via a belt to the blade. It is transmitted to the transmission mechanism 131. Instead, the work motor 4W can be arranged on the front side of the battery pack 6. At that time, the PTO shaft including the output shaft and the relay shaft from the work motor 4W is extended forward in the longitudinal direction of the vehicle body, and the power from the work motor 4W is transmitted to the mower unit 13 via the PTO shaft. It is transmitted to the blade transmission mechanism 131.

  The present invention can be applied to a battery pack mounted on an electric work vehicle such as an electric mower, an electric rice transplanter, and an electric tractor, and such an electric work vehicle.

4: Motor 4L: Left motor 4R: Right motor 10: Car body 11: Front wheel unit 12L: Left rear wheel 12R: Right rear wheel 13: Mower unit 20: Car body frame 21: Left frame 22: Right frame 30L: Left transmission case 30R : Right transmission case 31L: Left rear axle case 31R: Right rear axle case 6: Battery pack 6B: Rear rectangular parallelepiped portion 6F: Front rectangular parallelepiped portion 6Fc: Central portion 6A: Battery module 6a: Battery cell 60: Battery case 60a: Upper Case 60b: Lower case 60f: Fin 611: Center part 612: Enlarged part 613: Lid 61: Front case part 62: Rear case part 63: Horizontal partition wall 64: Vertical partition wall 68: Electrical unit 69: Circulation fan

Claims (7)

A sealed battery case comprising a front case portion and a rear case portion;
A horizontal partition wall that divides the interior of the front case portion into a first space and a second space in the vertical direction and divides the interior of the rear case portion into a third space and a fourth space in the vertical direction;
A battery electrical unit housed in one of the first space, the second space, the third space, and the fourth space;
A battery module housed in each of the remaining spaces of the first space, the second space, the third space, and the fourth space;
A battery pack for an electric work vehicle.   2. The battery pack for an electric work vehicle according to claim 1, further comprising a circulation fan that creates a longitudinal airflow that circulates through the first space, the second space, the third space, and the fourth space.   The battery pack for an electric work vehicle according to claim 2, wherein the circulation fan is housed in the same space as the battery electrical unit.   The rear case portion is offset upward with respect to the front case portion, and the battery case has a three-dimensional shape that forms a step between the front case portion and the rear case portion. The battery pack for electric work vehicles as described in any one of 1-3.   5. The battery pack for an electrically operated vehicle according to claim 1, wherein the battery case is provided with an opening that exposes the battery electrical unit to the outside and is closed by a lid. 6.   The battery pack for an electric work vehicle according to any one of claims 1 to 5, wherein fins for cooling are formed on a wall surface of the battery case. An electric work vehicle equipped with the battery pack for an electric work vehicle according to any one of claims 1 to 6,
A left frame and a right frame extending in the longitudinal direction of the vehicle body with a gap in the transverse direction of the vehicle body are provided,
A front end portion of the battery pack between the left rear wheel disposed outside the left frame in the vehicle transverse direction and the right rear wheel disposed outside the right frame in the vehicle transverse direction. The electric work vehicle is arranged so that is positioned in front of the axle of the rear wheel unit.

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