Electric tractor for agriculture and power transmission device of electric tractor for agriculture

Abstract

The present invention relates to a power transmission technology of an electric tractor for agriculture. According to the present invention, a power transmission device is disposed between a drive motor and a transmission, and the power transmission device forms a first transmission path through which a rotational force of the drive motor is transmitted to the transmission and a second transmission path through which a rotational force of the drive motor is transmitted to a hydraulic pump. When the present invention is applied thereto, a separate inverter and electric motor for operating an actuator such as a hydraulic pump can be omitted so that the production cost thereof is reduced.

Description

Agricultural electric tractors and power transmissions for agricultural electric tractors

[0001] The present invention relates to a power transmission technology for an agricultural electric tractor.

[0002] An agricultural tractor is a work vehicle that can perform agricultural work by replacing multiple work machines.

[0003] Agricultural tractors require both torque and hydraulic power for driving and operation. Torque is used to turn the wheels and various other rotations in the implements. Hydraulic power is used for steering and the operation of various cylinders.

[0004] The operation of agricultural tractors requires that the hydraulic pressure be constantly filled.

[0005] In agricultural tractors, rotational power is generated by the engine, and hydraulic pressure is generated by the hydraulic pump.

[0006] In agricultural tractors with engines, the hydraulic pump operates with power derived directly from the engine.

[0007] For example, an agricultural tractor has two axles that rotate together, driven by an engine. One of the two axles is a hollow shaft. The other is a central shaft coaxial with the hollow shaft and located within the hollow shaft.

[0008] The rotational power of the hollow shaft is input to the transmission, and the rotational power of the central shaft is input to the hydraulic pump via the power take-off (PTO). Here, the rotational power of the central shaft can be output to the hydraulic pump from the rear end after passing through the transmission. This structure allows the hydraulic pump to generate hydraulic pressure regardless of whether the transmission is operating.

[0009] Meanwhile, recent advances in battery technology have led to the development of electric agricultural tractors.

[0010] In electric agricultural tractors, batteries replace the engines of the past.

[0011] Agricultural electric tractors have a power distributor located between the battery and each electrical load. The battery's power is then distributed to each electrical load, such as the drive motor. In other words, in agricultural electric tractors, the drive motor is powered by the battery. The rotational force of the motor shaft, driven by the drive motor, rotates the wheels.

[0012] Of course, agricultural electric tractors also require hydraulic pumps for steering and other tasks. However, unlike engines, batteries cannot be equipped with a power take-off device. Instead, as shown in FIG. 1, the hydraulic pump (170) can be operated using power supplied through one of the lines distributed from the power distributor (130). Regarding this technology, Korean Patent No. 10-2336159 (hereinafter referred to as "prior art") has been disclosed. The prior art is designed to include an auxiliary drive motor in addition to the main drive motor and to operate the hydraulic pump using the power of the auxiliary drive motor.

[0013] However, the main and auxiliary drive motors are AC motors to ensure high-voltage power efficiency and power. Consequently, a first inverter for the main drive motor and a second inverter for the auxiliary drive motor are required to convert the battery's DC power into AC power. This, in turn, increases the production cost due to the expensive addition of the second inverter and auxiliary drive motor, complicates the layout design for the second inverter and auxiliary drive motor, and consequently increases the production cost.

[0014] The present invention was conceived from consideration of a technology that can simplify the power for generating hydraulic pressure in an agricultural electric tractor.

[0015] An agricultural electric tractor according to the present invention comprises: a battery for providing electric power; a drive motor for generating rotational force by the electric power of the battery; a power transmission device for outputting the rotational force generated by the drive motor to a first output point through a first transmission path and to a second output point through a second transmission path; a transmission for receiving the rotational force output to the first output point by the power transmission device; and an actuator for operating by receiving the rotational force output to the second output point by the power transmission device; wherein the first output point and the second output point are spaced apart from each other.

[0016] The above actuator is placed below the above driving motor.

[0017] The power transmission device is arranged between the drive motor and the transmission, and the actuator is arranged in the same direction as the drive motor.

[0018] The output direction of the rotational force through the first transmission path and the output direction of the rotational force through the second transmission path are opposite directions.

[0019] The above actuator may be a hydraulic pump that supplies hydraulic pressure.

[0020] The above actuator may be a compressor that compresses refrigerant.

[0021] A power transmission device of an agricultural electric tractor according to the present invention comprises: a transmission mechanism that forms a transmission path through which rotational force input to an input point goes to a first output point and outputs the rotational force to the first output point through the transmission path; an extraction mechanism that extracts rotational force from the transmission mechanism, forms an extraction path through which the rotational force extracted from the transmission mechanism goes to a second output point, and outputs the rotational force to the second output point through the extraction path; and a casing that accommodates the transmission mechanism and the extraction mechanism; wherein the first output point and the second output point are spaced apart from each other.

[0022] In the above transmission path, the rotational speed is reduced.

[0023] The above transmission mechanism includes a first output shaft through which rotational force is output via the transmission path; and the extraction mechanism includes a second output shaft through which rotational force is output via the extraction path; wherein the rotational direction of the first output shaft and the rotational direction of the second output shaft are opposite.

[0024] The output direction in which the rotational force is output through the above transmission path and the output direction in which the rotational force is output through the above extraction path are opposite.

[0025] The above-mentioned extraction mechanism includes an extraction gear that rotates according to the operation of the transmission mechanism by extracting rotational force from the transmission mechanism; an extraction shaft that is coupled with the extraction gear and rotates together with the extraction gear; a second output gear that is engaged with the extraction gear and rotates together with the extraction gear; and a second output shaft that is coupled with the second output gear and rotates together with the second output gear to output rotational force to the second output point.

[0026] The transmission mechanism includes an input shaft that rotates by a rotational force input to the input point; an input gear coupled to the input shaft and rotating together with the input shaft; a driven gear that meshes with the input gear and rotates together with the input gear; a driven shaft coupled to the driven gear and rotating together with the driven gear; a linkage gear coupled to the driven shaft and rotating in conjunction with the rotation of the driven gear and installed spaced apart from the driven gear; a first output gear that meshes with the linkage gear and rotates together with the linkage gear; and a first output shaft coupled to the first output gear and rotating together with the first output gear to output a rotational force to the first output point; wherein the transmission path sequentially passes through the input shaft, the input gear, the driven gear, the driven shaft, the linkage gear, the first output gear, and the first output shaft.

[0027] The above-described extraction mechanism includes an extraction gear that is engaged with the linkage gear and rotates together with the linkage gear to extract rotational force from the transmission mechanism; an extraction shaft that is engaged with the extraction gear and rotates together with the extraction gear; a second output gear that is engaged with the extraction gear and rotates together with the extraction gear; and a second output shaft that is engaged with the second output gear and rotates together with the second output gear to output rotational force to the second output point; wherein the extraction path sequentially passes through the extraction gear, the second output gear, and the second output shaft.

[0028] The rotational power input from the drive motor through the input point is output toward the transmission through the first output point, and the rotational power input from the drive motor through the input point is output toward the hydraulic pump through the second output point, and the second output point is located below the input point, thereby allowing the hydraulic pump to be placed below the drive motor.

[0029] According to the present invention, a separate inverter and electric motor for operating a hydraulic pump can be omitted, so the following effects are achieved.

[0030] First, production costs can be reduced.

[0031] Second, since layout becomes easier, space design becomes simpler, and production costs can be further reduced.

[0032] Third, the power efficiency of the battery can be improved because the weight can be reduced.

[0033] Fourth, the layout design for balancing the left and right weight of agricultural electric tractors can become easier.

[0034] Figure 1 is a reference diagram for explaining the hydraulic pressure generation structure in a typical agricultural electric tractor.

[0035] Figure 2 is a configuration diagram of an agricultural electric tractor according to one embodiment of the present invention.

[0036] Fig. 3 is a reference diagram for explaining a power relay applied to the agricultural electric tractor of Fig. 2.

[0037] Figure 4 is a reference drawing for explaining the arrangement of major components of the agricultural electric tractor of Figure 2.

[0038] Figures 5 and 6 are reference drawings for explaining the power transmission path in the power transmission device applied to the agricultural electric tractor of Figure 2.

[0039] Fig. 7 is a reference drawing for explaining the arrangement position of the hydraulic pump applied to the agricultural electric tractor of Fig. 2.

[0040] Figures 8 and 9 are reference drawings for explaining the structure of a power transmission device that can be applied to the agricultural electric tractor of Figure 2.

[0041] A preferred embodiment according to the present invention is described with reference to the attached drawings, but for the sake of brevity, descriptions of well-known components are omitted or compressed as much as possible.

[0042] Description of agricultural tractors

[0043] Figure 2 is a configuration diagram of an agricultural tractor (200) according to one embodiment of the present invention.

[0044] The agricultural tractor (200) of FIG. 2 includes a battery (210), a driving motor (220), a power relay (230), an inverter (240), a power transmission unit (250), a transmission (260), and a hydraulic pump (270).

[0045] The battery (210) is provided to provide high voltage (DC 360 V) power used as driving force for agricultural electric vehicles or for agricultural work.

[0046] The drive motor (220) generates rotational force by operating with power from the battery (210).

[0047] The drive motor (220) has a rotatable motor shaft (221), and when the drive motor (220) operates, the motor shaft (221) rotates.

[0048] According to the present invention, the rotational power of the motor shaft (221) is utilized as driving power, working power, steering power, hydraulic power, etc.

[0049] The power relay (230) relays the power provided from the battery (210) to the drive motor (220).

[0050] The power relay (230) may be a power distributor or may include a power distributor. Thus, as shown in FIG. 3, the power relay (230) distributes the power of the high-voltage battery (110) to the drive motor (220), compressor (280), heater (H), fan motor (F), etc.

[0051] The inverter (240) converts direct current power from the power relay (230) into alternating current power and provides it to the drive motor (220). For this purpose, the inverter (240) is placed between the power relay (230) and the drive motor (220).

[0052] The power transmission unit (250) transmits the rotational power of the motor shaft (221) to the transmission (260) and the hydraulic pump (270), respectively.

[0053] The power transmission unit (250) is arranged between the drive motor (220) and the transmission (260). More specifically, as shown in FIG. 4, the front end of the power transmission unit (250) is coupled to the rear end of the drive motor (220), and the rear end of the power transmission unit (250) is coupled to the front end of the transmission unit (260). Therefore, the drive motor (220) is arranged in front of the power transmission unit (250), and the transmission (260) is arranged in the rear of the power transmission unit (250).

[0054] As shown in the reference drawing of Fig. 5, the power transmission device (250) of the present invention has two transmission paths (TC1, TC2) for transmitting rotational power. That is, the power transmission device (250) has one input point (IP) where rotational power is input, but two output points (OP2) where rotational power is output.

[0055] The rotational force input from the motor shaft (221) is output to the first output point (OP1) through the first transmission path (TC1) among the two transmission paths (TC1, TC2).

[0056] In addition, the rotational force input from the motor shaft (221) is output to the second output point (OP2) through the second transmission path (TC2) among the two transmission paths (TC1, TC2). Here, a part of the second transmission path (TC2) is a drawing path (DC) that branches off from the first transmission path (TC1) and draws the rotational force from the first transmission path (TC1).

[0057] The rotational power output to the first output point (OP1) through the first transmission path (TC1) is input to the transmission (260). And according to a preferred example, the rotational power output to the second output point (OP2) through the second transmission path (TC2) is input to the hydraulic pump (270). Of course, the first output point (OP1) and the second output point (OP2) are different from each other. Naturally, the first output point (OP1) and the second output point (OP2) are mutually spaced.

[0058] According to a preferred example of the present invention, the first transmission path (TC1) may be provided as a reduction path that outputs rotational force at a rotational speed reduced from the rotational speed of the motor shaft (221). In this case, rotational force with increased torque can be input to the transmission (260) as the rotational speed is reduced. Therefore, there is no need to place a separate reduction gear between the drive motor (220) and the transmission (260).

[0059] Additionally, the output direction of the rotational force through the first transmission path (TC1) is rearward. On the other hand, the output direction of the rotational force through the second transmission path (TC2) is forward. In other words, the output directions of the rotational force through the first transmission path (TC1) and the output directions of the rotational force through the second transmission path (TC2) are opposite.

[0060] The present invention has a particularly important feature in the power transmission unit (250). Therefore, the structure of the power transmission unit (250) will be described in more detail in a separate table of contents.

[0061] The transmission (260) is for controlling the rotation direction or rotation speed of the wheel (not shown).

[0062] The rotational power output from the first output point (OP1) is input to the transmission (260).

[0063] The hydraulic pump (270) generates hydraulic pressure required for steering and operation of various cylinders.

[0064] The rotational force output from the second output point (OP2) is input to the hydraulic pump (270). In other words, the rotational force output from the second output point (OP2) is used to operate the hydraulic pump (270).

[0065] The hydraulic pump (270) is an actuator that operates with the rotational force output from the second output point (OP2). Therefore, as in the modified example of FIG. 6, a compressor (280) that compresses refrigerant may be placed instead of the hydraulic pump (270), and the compressor (280) may be operated with the rotational force output from the second output point (OP2). That is, according to the modified example of FIG. 6, the actuator that operates with the rotational force output from the second output point (OP2) is the compressor (280). Any type of actuator that can operate with rotational force may be installed to replace the hydraulic pump (270).

[0066] However, the agricultural electric tractor (200) must always be filled with hydraulic pressure when the engine is turned on. Therefore, the hydraulic pump (270) must be constantly operated. Accordingly, as shown in FIG. 4, the hydraulic pump (270) and the power transmission unit (250) are directly connected. However, if the hydraulic pump (270) is replaced with an actuator other than the hydraulic pump, selective operation may be required depending on the replaced actuator. In this case, this problem can be easily solved by interposing a clutch between the actuator and the power transmission unit (250).

[0067] According to the present invention, the rotational force input from one input point (IP) in the power transmission device (250) is divided into two and output to the first output point (OP1) and the second output point (OP2), respectively. Then, the rotational force output from the first output point (OP1) is input to the transmission (260), and the rotational force output from the second output point (OP2) is input to the hydraulic pump (270). Accordingly, the pump shaft (271) is rotated by the rotational force generated from the driving motor (220), thereby operating the hydraulic pump (270). Therefore, when the present invention is applied, a separate inverter and electric motor are not required to operate the hydraulic pump (270). This reduces the production cost and facilitates the design of the space for installing components.

[0068] The spatial arrangement and operation of the main components of the agricultural electric tractor (200) described above will be explained.

[0069] According to a preferred example, the hydraulic pump (270) is placed below the drive motor (220) as in FIG. 4.

[0070] The power transmission unit (250) is positioned at the rear of the drive motor (220), and the transmission (260) is positioned at the rear of the power transmission unit (250). In other words, the drive motor (220) is positioned at the front of the power transmission unit (250), and the transmission (260) is positioned at the rear of the power transmission unit (250). In addition, the drive motor (220) and the power transmission unit (250) are directly connected by a shaft coupling, and the power transmission unit (250) and the transmission (260) are directly connected by a shaft coupling.

[0071] Additionally, the hydraulic pump (270) is positioned in front of the power transmission unit (250). Therefore, the hydraulic pump (270) is positioned in front of the power transmission unit (250) and below the driving motor (220).

[0072] With respect to the power transmission unit (250), the drive motor (220) and the hydraulic pump (270) are positioned in the front in the same direction, and the transmission (260) is positioned in the rear. Therefore, the output direction of the rotational force through the first transmission path (TC1) and the output direction of the rotational force through the second transmission path (TC2) must be opposite.

[0073] The power transmission (250) outputs rotational power to the rear transmission (260) through the first transmission path (TC1).

[0074] Additionally, the power transmission unit (250) outputs rotational power to the front hydraulic pump (270) through the second transmission path (TC2).

[0075] The design of the spatial arrangement and the direction of output of rotational force as shown in FIGS. 4 and 5 facilitates the design of the spatial arrangement of the drive motor (220), power transmission unit (250), transmission (260), and hydraulic pump (270).

[0076] In a generally considered agricultural electric tractor (200), the transmission (260) has a very large number of gear ratios. Furthermore, the outer dimensions of the transmission (260) are correspondingly large. Therefore, the space occupied by the transmission (260) is naturally very high. Therefore, if both the transmission (260) and the hydraulic pump (270) must be placed at the rear of the drive motor (220), securing the installation space for the hydraulic pump (270) can become very complex.

[0077] However, following the arrangement structure of FIGS. 4 and 5, it becomes possible to install the hydraulic pump (270) avoiding the transmission (260). In particular, as shown in FIG. 7, it is necessary to take into account that the vertical width (H2) of the transmission (260) is wider than the vertical width (H1) of the drive motor (220).

[0078] Referring to Fig. 7, it can be seen that sufficient installation space (IS) can be secured to place the hydraulic pump (260) below the drive motor (220). Accordingly, by placing the drive motor (220) and the hydraulic pump (260) in the same direction, the space design for installing components of the agricultural electric tractor (200) can be made easier.

[0079] Description of the power transmission

[0080] Fig. 8 is a schematic diagram of the internal structure of a power transmission device (250) applicable to the agricultural tractor of Fig. 2, and Fig. 9 is a structural diagram showing the power transmission structure of the power transmission device (250) of Fig. 8.

[0081] Referring to FIGS. 8 and 9 in comparison with each other, a power transmission device (250) according to one embodiment of the present invention includes a transmission mechanism (251), an extraction mechanism (252), and a casing (253).

[0082] The transmission mechanism (251) forms a first transmission path (TC1) through which the rotational force input to the input point (IP) goes to the first output point (OP1). That is, the transmission mechanism (251) outputs the rotational force input to the input point (IP) to the first output point (OP1) through the first transmission path (TC1).

[0083] According to a preferred example, the first transmission path (TC1) can be implemented so that a reduction in rotational speed is achieved.

[0084] The transmission mechanism (251) includes an input shaft (251a), an input gear (251b), a driven gear (251c), a driven shaft (251d), a linkage gear (251e), a first output gear (251f), and a first output shaft (251g).

[0085] The input shaft (251a) is provided to receive the rotational force input to the input point (IP). In other words, the input shaft (251a) rotates by the rotational force input to the input point (IP).

[0086] Depending on the implementation, the input shaft (251a) may be the motor shaft (221) of the driving motor (220).

[0087] Depending on the implementation, the input shaft (251a) can be directly connected to the motor shaft (221) of the driving motor (220).

[0088] Depending on the implementation, a third coupling shaft may be interposed between the input shaft (251a) and the motor shaft (221) of the drive motor (220).

[0089] In this way, the rotational power input through the input point (IP) comes from the drive motor (220). According to the most preferred example, the drive motor (220) and the power transmission unit (250) are directly connected through a shaft connection without the intervention of other connecting elements.

[0090] The input gear (251b) is coupled to the input shaft (251a). Therefore, the input gear (251b) rotates in the same rotational direction as the input shaft (251a). Therefore, the rotational force input to the input point (IP) is transmitted to the input gear (251b) via the input shaft (251a).

[0091] The input shaft (251a) functions as a drive shaft for the operation of the power transmission device (250), and the input gear (251b) functions as a drive gear coupled to the drive shaft.

[0092] The driven gear (251c) can be arranged approximately lower than the input gear (251b) and is in gear meshing with the input gear (251b). Accordingly, when the input gear (251b) rotates in the forward direction, the driven gear (251c) rotates in the reverse direction. That is, the rotational force is transmitted from the input gear (251b) to the driven gear (251c), and the rotational direction of the input gear (251b) and the rotational direction of the driven gear (251c) are opposite. Here, the forward direction is defined as the rotational direction of the input shaft (251a), and the reverse direction is defined as the direction opposite to the rotational direction of the input shaft (251a).

[0093] A driven gear (251c) is coupled to the driven shaft (251d). Therefore, as the driven gear (251c) rotates, the driven shaft (251d) also rotates in the same rotational direction as the driven gear (251c).

[0094] The linkage gear (251e) is coupled to the driven shaft (251d). Therefore, the linkage gear (251e) rotates together with the driven gear (251c) and the driven shaft (251d) in the same direction.

[0095] The linkage gear (251e) is spaced apart from the driven gear (251c) and is placed at the rear of the driven gear (251c).

[0096] Rotational power is transmitted from the driven gear (251c) through the driven shaft (251d) to the linkage gear (251e).

[0097] To achieve appropriate deceleration, it is desirable that the radius of the linkage gear (251e) be smaller than the radius of the driven gear (251c).

[0098] The first output gear (251f) is positioned approximately above the linkage gear (251e) and is in gear meshing with the linkage gear (251e). Accordingly, when the linkage gear (251e) rotates in the reverse direction, the first output gear (251f) rotates in the forward direction. In other words, the rotational force is transmitted from the linkage gear (251e) to the first output gear (251f), and the rotational direction of the linkage gear (251e) and the rotational direction of the first output gear (251f) are opposite.

[0099] A first output gear (251f) is coupled to the first output shaft (251g). Therefore, by the rotation of the first output gear (251f), the first output shaft (251g) also rotates in the same rotational direction as the first output gear (251f). Rotational power is output to the first output point (OP1) by the first output shaft (251g).

[0100] Depending on the implementation, the first output shaft (251g) may be a transmission shaft (261) of a transmission (260).

[0101] Depending on the implementation, the first output shaft (251g) can be directly connected to the transmission shaft (261) of the transmission (260).

[0102] Depending on the implementation, a third connecting shaft may be interposed between the first output shaft (251g) and the transmission shaft (261) of the transmission (260).

[0103] In this way, the rotational power output through the first output point (OP1) is output toward the transmission (260). According to one example, the power transmission (250) and the transmission (260) are directly connected through shaft coupling without the intervention of other connecting elements.

[0104] The first transmission path (TC1) sequentially passes through the input shaft (251a), input gear (251b), driven gear (251c), driven shaft (251d), linkage gear (251e), first output gear (251f), and first output shaft (251g).

[0105] The rotation directions of the input shaft (251a) and the first output shaft (251g) are the same in the forward direction.

[0106] According to a preferred example of the present invention, the first transmission path (TC1) is a deceleration path in which the rotational speed is reduced. Accordingly, the rotational speed of the first output shaft (251g) becomes slower than the rotational speed of the input shaft (251a). Conversely, the torque of the first output shaft (251g) becomes higher than the torque of the input shaft (251a).

[0107] For deceleration, the radius of the driven gear (251c) is implemented to be larger than that of the input gear (251b). Therefore, the rotational speed is initially reduced in the process of transmitting rotational power from the input gear (251b) to the driven gear (251c).

[0108] In addition, the radius of the first output gear (251f) is implemented to be larger than that of the linkage gear (251e) for deceleration. Therefore, the rotational speed is secondarily reduced in the process of transmitting rotational power from the linkage gear (251e) to the first output gear (251f).

[0109] If the first transmission path (TC1) is implemented as a deceleration path in which the rotational speed is reduced, a separate reduction gear provided between the driving motor (220) and the transmission (260) can be omitted.

[0110] The first transmission path (TC1) is implemented to achieve deceleration in two stages, thereby ensuring that deceleration is achieved at an appropriate deceleration ratio even in a narrow deployment area.

[0111] In addition, it is preferable that the input shaft (251a) and the first output shaft (251g) be arranged coaxially with each other so that an appropriate reduction ratio can be implemented in a narrow layout area.

[0112] The extraction mechanism (252) is provided to extract rotational power from the transmission mechanism (251).

[0113] The extraction mechanism (252) forms a extraction path (DC) through which the rotational force extracted from the transmission mechanism (251) goes to the second output point (OP2). That is, the extraction mechanism (252) outputs the rotational force branched from the transmission mechanism (251) to the second output point (OP2) through the extraction path (DC).

[0114] The output path (DC) forms part of the second transmission path (TC2) through which the rotational force input to the input point (IP) goes to the second output point (OP2).

[0115] The extraction mechanism (252) includes an extraction gear (252a), an extraction shaft (252b), a second output gear (252c), and a second output shaft (252d).

[0116] The extraction gear (252a) is for extracting rotational power from the transmission mechanism (251).

[0117] According to a preferred example, the take-out gear (252a) is in gear mesh with the linkage gear (251e). Accordingly, when the linkage gear (251e) rotates in the reverse direction, the take-out gear (252a) rotates in the forward direction.

[0118] Rotational power is transmitted from the linkage gear (251e) to the take-off gear (252a). That is, the rotational power input to the input point (IP) is branched by the take-off gear (252a). In other words, the first transmission path (TC1) and the second transmission path (TC2) are separated by the take-off gear (252a).

[0119] In the examples of FIGS. 8 and 9, the extraction gear (252a) is positioned approximately lower than the linkage gear (251e).

[0120] A take-out gear (252a) is coupled to the take-out shaft (252b).

[0121] The take-out shaft (252b) rotates together with the take-out gear (252a) and holds the position of the take-out gear (252a).

[0122] The second output gear (252c) is in gear meshing with the take-out gear (252a). Accordingly, when the take-out gear (252a) rotates in the forward direction, the second output gear (252c) rotates in the reverse direction.

[0123] The second output gear (252c) is provided approximately below the take-out gear (252a), and the rotational power is transmitted from the take-out gear (252a) to the second output gear (252c).

[0124] A second output gear (252a) is coupled to the second output shaft (252d). Therefore, when the second output gear (252c) rotates in the reverse direction, the second output shaft (252c) also rotates in the reverse direction.

[0125] The rotational power is transmitted from the second output gear (252c) to the second output shaft (252d), output to the second output point (OP1), and then input to the hydraulic pump (270).

[0126] Depending on the implementation, the second output shaft (252d) may be a pump shaft (271) of a hydraulic pump (270).

[0127] Depending on the implementation, the second output shaft (252d) can be directly connected to the pump shaft (271).

[0128] Depending on the implementation, a third transmission shaft may be interposed between the second output shaft (252d) and the pump shaft (271).

[0129] Ultimately, the rotational power output through the second output point (OP2) is output toward the hydraulic pump (270). According to the most preferred example, the power transmission unit (250) and the hydraulic pump (270) are directly connected through a shaft connection without the intervention of other connecting elements. Therefore, the hydraulic pump (270) can be installed by utilizing the installation space (IS) located below the drive motor (220). That is, in a layout structure in which the transmission (260) is directly connected to the rear end of the power transmission unit (250), the hydraulic pump (270) can be installed by utilizing the installation space (IS) located below the drive motor (220) where there is ample space. In addition, if the hydraulic pump (270) is installed directly below the drive motor (250), the layout design for balancing the overall left and right weight of the agricultural electric tractor (200) can also become easier.

[0130] The take-out path (DC) sequentially passes through the take-out gear (252a), the second output gear (252c), and the second output shaft (252d). And the second transmission path (TC2) passes through the input shaft (251a), the input gear (251b), the driven gear (251c), the driven shaft (251d), the linkage gear (251e), the take-out gear (252a), the second output gear (252c), and the second output shaft (252d).

[0131] In this way, the rotational power input to the input point (IP) is divided into two by the linkage gear (251e) and transmitted to the first output gear (251f) and the take-out gear (252a), respectively.

[0132] Meanwhile, according to a preferred example of the present invention, the hydraulic pump (270) is disposed below the drive motor (220). And, both the drive motor (220) and the hydraulic pump (270) are disposed in front of the power transmission device (250). Therefore, the rotation direction of the motor shaft (221) and the rotation direction of the pump shaft (271) need to be opposite to each other. That is, the rotation direction of the input shaft (251a) and the rotation direction of the first output shaft (251g) are the same, but the rotation direction of the second output shaft (252d) must be opposite to the rotation directions of the input shaft (251a) and the first output shaft (251g).

[0133] In the examples of FIGS. 8 and 9, a take-out gear (252a) is positioned between the linkage gear (251e) and the second output gear (252c). Therefore, the second output shaft (252d) rotates in a direction opposite to the rotational direction of the input shaft (251a) and the first output shaft (251g).

[0134] Additionally, in the examples of FIGS. 8 and 9, the take-out gear (252a) has a rotational force take-out function and a function of changing the rotational direction of the rotational force output to the second output point (OP2).

[0135] If the rotational force going to the hydraulic pump (270) is directly output from the take-off shaft (252a), the forward rotation, which is opposite to the proper rotational direction of the pump shaft (271) for operating the hydraulic pump (270), is input to the hydraulic pump (270). Therefore, by configuring a separate second output gear (252c) in addition to the take-off gear (252b), the rotational force going to the hydraulic pump (270) is optimized.

[0136] Furthermore, the take-out gear (252a) may be implemented to mesh with the driven gear (251c). However, it is necessary to consider that the radius of the driven gear (251c) is larger than the radius of the linkage gear (251e). When the take-out gear (252a) meshes with the driven gear (251c), the density of the gears may decrease and the width of the power transmission unit (250) may become wider than when the take-out gear (252a) meshes with the linkage gear (251e). Therefore, by meshing the take-out gear (252a) with the linkage gear (251e), the width and size of the power transmission unit (250) can be minimized, and the installation area can be reduced accordingly.

[0137] Furthermore, in order to achieve an appropriate rotation speed of the pump shaft (271), the gear ratio of the linkage gear (251e) and the take-out gear (252a), and the gear ratio of the take-out gear (252a) and the second output gear (252c) can be appropriately adjusted. In other words, in order to achieve an appropriate rotation speed of the pump shaft (271), the radius of the take-out gear (252a) and the second output gear (252c) can be selected to match the appropriate rotation speed of the pump shaft (271).

[0138] The casing (253) houses a reduction mechanism (251) and an extraction mechanism (252) inside.

[0139] Additionally, the casing (253) also has the function of supporting the reduction mechanism (251) and the extraction mechanism (252).

[0140] Next, the operation of the power transmission device (250) as described above will be described.

[0141] When rotational force is input from the drive motor (220) to the input point (IP), the input shaft (251a) rotates in the forward direction. Accordingly, the input gear (251b), the driven gear (251c), the driven shaft (251d), the linkage gear (251e), the first output gear (251f), and the first output shaft (251g) rotate, so that the rotational force of the first output shaft (251g) is output from the first output point (OP1) toward the rear transmission (260). In addition, the rotational speed of the first output shaft (252) is reduced compared to the rotational speed of the input shaft (251a). At this time, the input shaft (251a), the input gear (251b), and the first output shaft (251g) rotate in the forward direction, and the driven gear (252c), the driven shaft (251d), and the linkage gear (251e) rotate in the reverse direction.

[0142] Meanwhile, the take-out gear (252a), the second output gear (252c), and the second output shaft (252d) are also rotated by the rotational force separated from the linkage gear (251e), so that the rotational force of the second output shaft (252d) is output toward the hydraulic pump (270) in front at the second output point (OP2). At this time, the take-out gear (252a) rotates in the forward direction, and the second output gear (252c) and the second output shaft (252d) rotate in the reverse direction.

[0143] The above-described embodiments merely illustrate preferred examples of the present invention, and it may have various applications. Therefore, the present invention should not be construed as limited to the above-described content. Instead, the scope of the present invention should be construed within the scope of the separately described claims and their equivalents.

Claims

1. Battery (210) providing power; A driving motor (220) that generates rotational force by the power of the above battery (210); A power transmission device (250) that outputs the rotational force generated from the above driving motor (220) to the first output point (OP1) through the first transmission path (TC1) and to the second output point (OP2) through the second transmission path (OP2); A transmission (260) that receives the rotational force output to the first output point (OP1) by the power transmission device (250); and An actuator that operates by receiving the rotational force output to the second output point (OP2) by the power transmission device (250); The above first output point (OP1) and the above second output point (OP2) are spaced apart. Agricultural electric tractor (200).

2. In paragraph 1, The above actuator is placed below the driving motor (220). Agricultural electric tractor (200).

3. In paragraph 1, The above power transmission device (250) is placed between the driving motor (220) and the transmission (260). The above actuator is placed in the same direction as the driving motor (220). Agricultural electric tractor (200).

4. In paragraph 1, The output direction of the rotational force through the first transmission path (TC1) and the output direction of the rotational force through the second transmission path (TC2) are opposite directions. Agricultural electric tractor (200).

5. In paragraph 1, The above actuator is a hydraulic pump (270) that supplies hydraulic pressure. Agricultural electric tractor (200).

6. In paragraph 1, The above actuator is a compressor (280) that compresses refrigerant. Agricultural electric tractor (200).

7. A transmission mechanism (251) that forms a transmission path (TC1) through which rotational force input to an input point (IP) goes to a first output point (OP1), and outputs the rotational force to the first output point (OP1) through the transmission path (TC1); A take-out mechanism (252) that takes out rotational force from the transmission mechanism (251), forms a take-out path (DC) through which the rotational force taken out from the transmission mechanism (251) goes to a second output point (OP2), and outputs the rotational force to the second output point (OP2) through the take-out path (DC); and It includes a casing (253) that accommodates the above transmission mechanism (251) and the above withdrawal mechanism (252); The above first output point (OP1) and the above second output point (OP2) are spaced apart. Power transmission (250) of an agricultural electric tractor (200).

8. In paragraph 7, In the above transmission path (TC1), the rotation speed is reduced. Power transmission (250) of an agricultural electric tractor (200).

9. In paragraph 7, The above transmission mechanism (251) It includes a first output shaft (251g) through which rotational force is output through the above transmission path (TC1); The above withdrawal mechanism (252) It includes a second output shaft (252d) through which rotational force is output through the above-mentioned extraction path (DC); The rotation direction of the first output shaft (251g) and the rotation direction of the second output shaft (252d) are opposite. Power transmission (250) of an agricultural electric tractor (200).

10. In paragraph 7, The output direction in which the rotational force is output through the above transmission path (TC1) and the output direction in which the rotational force is output through the above withdrawal path (DC) are opposite. Power transmission (250) of an agricultural electric tractor (200).

11. In paragraph 7, The above withdrawal mechanism (252) A pull-out gear (252a) that rotates according to the operation of the transmission mechanism (251) by extracting rotational force from the transmission mechanism (251); A pull-out shaft (252b) that is coupled with the pull-out gear (252a) and rotates together with the pull-out gear (252a); A second output gear (252c) that is engaged with the above-mentioned extraction gear (252a) and rotates together with the above-mentioned extraction gear (252a); and A second output shaft (252d) that is coupled with the second output gear (252c) and rotates together with the second output gear (252c) to output rotational force to the second output point (OP2); Power transmission (250) of an agricultural electric tractor (200).

12. In paragraph 7, The above transmission mechanism (251) An input shaft (251a) that rotates by the rotational force input to the above input point (IP); An input gear (251b) coupled to the input shaft (251a) and rotating together with the input shaft (251a); A driven gear (251c) that is engaged with the input gear (251b) and rotates together with the input gear (251b); A driven shaft (251d) that is coupled with the driven gear (251c) and rotates together with the driven gear (251c); A linkage gear (251e) coupled to the above-mentioned driven shaft (251d) and rotating in conjunction with the rotation of the above-mentioned driven gear (251c), and installed spaced apart from the above-mentioned driven gear (251c); A first output gear (251f) that is meshed with the above-mentioned linkage gear (251e) and rotates together with the above-mentioned linkage gear (251e); and The first output gear (251f) is coupled to the first output shaft (251g) and rotates together with the first output gear (251f) to output rotational force to the first output point (OP1); The above transmission path (TC1) sequentially passes through the input shaft (251a), the input gear (251b), the driven gear (251c), the driven shaft (251d), the linkage gear (251e), the first output gear (251f), and the first output shaft (251g). Power transmission (250) of an agricultural electric tractor (200).

13. In paragraph 12, The above withdrawal mechanism (252) A take-out gear (252a) that is engaged with the above-mentioned linkage gear (251e) and rotates together with the above-mentioned linkage gear (251e) to extract rotational power from the above-mentioned transmission mechanism (251); A pull-out shaft (252b) that is coupled with the pull-out gear (252a) and rotates together with the pull-out gear (252a); A second output gear (252c) that is engaged with the above-mentioned extraction gear (252a) and rotates together with the above-mentioned extraction gear (252a); and The second output gear (252c) is coupled to the second output shaft (252d) and rotates together with the second output gear (252c) to output rotational force to the second output point (OP2); The above-mentioned extraction path (DC) sequentially passes through the extraction gear (252a), the second output gear (252c), and the second output shaft (252d). Power transmission (250) of an agricultural electric tractor (200).

14. In paragraph 7, The rotational power input from the drive motor (220) through the above input point (IP) is output to the transmission (260) through the first output point (OP1). The rotational power input from the drive motor (220) through the above input point (IP) is output toward the hydraulic pump (270) through the second output point (OP2). The second output point (OP2) is located below the input point (IP), thereby allowing the hydraulic pump (270) to be placed below the driving motor (220). Power transmission (250) of an agricultural electric tractor (200).

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