rice transplanter

Abstract

A rice transplanter includes a seedling transplanting device that transplants seedlings to a field surface, and a hydrostatic continuously variable transmission device (45) having a hydraulic pump to which power from an engine is transmitted and a hydraulic motor that outputs power. The continuously variable transmission device (45) has a high-pressure side oil passage that supplies pressure oil from the hydraulic pump to the hydraulic motor, and a low-pressure side oil passage that supplies pressure oil from the hydraulic motor to the hydraulic pump. The continuously variable transmission device (45) is equipped with a pressure reduction portion (75) that is connected to the high-pressure side oil passage and reduces the pressure of the pressure oil supplied to the hydraulic motor.

Description

Technical Field

[0001] This invention relates to a rice transplanter. Background Technology

[0002] Conventional rice transplanters, such as those described in Patent Document 1, transmit power from an engine to the seedling transplanting device via a plant spacing transmission device (a continuously variable transmission in Patent Document 1). By operating the plant spacing transmission device, the plant spacing of the seedling transplanting device can be set to the desired interval.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-060340 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Such rice transplanters include those described in Patent Document 1, which use a hydrostatic continuously variable transmission as a plant spacing speed change device.

[0008] A hydrostatic continuously variable transmission (CVT) includes: a hydraulic pump that transmits power from the engine; a hydraulic motor that outputs power; an oil circuit that supplies pressurized oil from the hydraulic pump to the hydraulic motor; and an oil circuit that supplies pressurized oil from the hydraulic motor to the hydraulic pump.

[0009] In traditional hydrostatic continuously variable transmissions (CVTs), the workload of the seedling transplanting device sometimes increases, leading to higher pressure of the working oil in the hydraulic circuit. This increased pressure can cause pulsation within the hydraulic circuit, resulting in abnormal noises.

[0010] Therefore, the object of the present invention is to provide a rice transplanter that can alleviate the problem of increased pressure of the working oil in the oil circuit of a continuously variable transmission (CVT).

[0011] Solution for solving the problem

[0012] The rice transplanter of the present invention comprises: a seedling transplanting device for transplanting seedlings into a field; and a hydrostatic continuously variable transmission (CVT) having a hydraulic pump that transmits power from an engine and a hydraulic motor that outputs power. The CVT has: a high-pressure side oil circuit for supplying pressurized oil from the hydraulic pump to the hydraulic motor; and a low-pressure side oil circuit for supplying pressurized oil from the hydraulic motor to the hydraulic pump. The CVT is equipped with a pressure reducing unit connected to the high-pressure side oil circuit to reduce the pressure of the pressurized oil supplied to the hydraulic motor.

[0013] According to the present invention, a pressure-reducing unit is provided in the high-pressure side oil circuit of a continuously variable transmission (CVT) where the pressure of the working oil inside the CVT increases when the load on the CVT increases. This structure reduces the pressure of the working oil in the high-pressure side oil circuit by means of the pressure-reducing unit, thus mitigating the situation where the pressure of the working oil in the high-pressure side oil circuit increases.

[0014] In this invention, it is preferred that the pressure-reducing part has a pressure relief valve.

[0015] According to this structure, the pressure of the working oil in the high-pressure side oil circuit is set by a pressure relief valve. When the pressure of the working oil rises above the set value, the pressure relief valve opens, thereby reducing the pressure of the working oil in the high-pressure side oil circuit. Therefore, by selecting a pressure relief valve with an appropriate set value during the design phase, the pressure reducing unit can adjust the pressure of the working oil in the high-pressure side oil circuit to an appropriate pressure.

[0016] In this invention, preferably, the pressure relief valve is connected to the high-pressure side oil circuit and the low-pressure side oil circuit.

[0017] Based on this structure, it can be configured as follows: when the pressure of the working oil in the high-pressure side oil circuit rises above the set value set by the pressure relief valve, the working oil in the high-pressure side oil circuit will flow to the low-pressure side oil circuit via the pressure relief valve. Therefore, by simply equipping the oil circuit connecting the high-pressure side oil circuit and the low-pressure side oil circuit with a pressure relief valve, a pressure reducing unit can be installed in the continuously variable transmission (CVT) through a simple design change.

[0018] In this invention, preferably, the pressure reducing unit has: a first oil passage connecting the high-pressure side oil passage to the pressure relief valve; and a second oil passage connecting the pressure relief valve to the low-pressure side oil passage, wherein a throttling orifice is provided in either the first oil passage or the second oil passage.

[0019] According to this structure, even if the pressure relief valve opens due to the increased pressure of the working oil in the high-pressure side oil circuit, the pressure of the working oil in the high-pressure side oil circuit can be prevented from dropping sharply through the throttling orifice.

[0020] In this invention, preferably, the throttling orifice is provided in the first oil passage, and the inner diameter of the throttling orifice is smaller than the inner diameter of the first oil passage.

[0021] According to this structure, a throttling orifice is provided in the oil circuit upstream of the pressure relief valve. This reduces the hydraulic pressure applied to the pressure relief valve and extends its lifespan.

[0022] In this invention, preferably, the pressure reducing unit has an accumulator that reduces the pressure of the pressure oil supplied to the hydraulic motor, and the accumulator is connected to the high-pressure side oil circuit via a throttle orifice.

[0023] According to this structure, by supplying the working oil in the high-pressure side oil circuit to the accumulator, the pressure of the working oil in the high-pressure side oil circuit can be reduced. Only an accumulator needs to be installed in the high-pressure side oil circuit; a pressure-reducing unit can be added to the continuously variable transmission (CVT) through a simple design change.

[0024] In this invention, preferably, the continuously variable transmission (CVT) is a transmission device that changes the speed of the power from the engine and transmits it to the seedling transplanting device to change the spacing between plants.

[0025] According to this structure, even if the working load of the seedling transplanting device increases, the pressure of the working oil in the high-pressure side oil circuit of the plant spacing speed change device can be reduced. Attached Figure Description

[0026] Figure 1 This is an overall side view of a ride-on rice transplanter.

[0027] Figure 2 This is an overall top view of a ride-on rice transplanter.

[0028] Figure 3 It is a longitudinal sectional top view showing the transmission structure.

[0029] Figure 4 It is a longitudinal sectional top view showing the transmission structure.

[0030] Figure 5 This is a diagram showing the structure of the pressure-reducing section.

[0031] Figure 6 This is a diagram showing the hydraulic circuit of the plant spacing speed change device and the pressure reduction section.

[0032] Figure 7 This is a side view showing the structure of the plant spacing speed change device and the fan. Detailed Implementation

[0033] This specific embodiment will be described based on the accompanying drawings. It should be noted that, unless otherwise specified, in the following description, the direction of arrow F in the figures is set to "forward," the direction of arrow B to "backward," the direction of arrow L to "left," and the direction of arrow R to "right." Furthermore, the direction of arrow U in the figures is set to "up," and the direction of arrow D to "down."

[0034] [Overall structure of the rice transplanter]

[0035] The following describes a riding-type rice transplanter (an example of a "rice transplanter") according to this embodiment. Figure 1As shown, in the riding rice transplanter, a linkage mechanism 3 and a hydraulic cylinder 4 for lifting and lowering the linkage mechanism 3 are provided at the rear of the body 11, which has a front wheel 1 on the right and left sides and a rear wheel 2 on the right and left sides. A seedling transplanting device 5 for transplanting seedlings into the field is supported at the rear of the linkage mechanism 3.

[0036] The seedling transplanting device 5 includes a transplanting transmission box 6 arranged at predetermined intervals along the left and right directions, a rotating box 7 supported in a rotatable manner on the right and left sides of the rear of the transplanting transmission box 6, a pair of transplanting arms 8 at both ends of the rotating box 7, a float 9, and a seedling carrier platform 10, etc.

[0037] [Structure near the driver's compartment]

[0038] like Figure 1 and Figure 2 As shown, the aircraft 11 is equipped with a driver's seat 13 and a steering wheel 14 for steering the front wheels 1.

[0039] Right and left support frames 16 are provided on the right and left sides of the front part of the body 11, and a seedling placement platform 15 is supported on the support frames 16. A support frame 17 is connected to the upper part of the right and left support frames 16.

[0040] A measuring device 18 is mounted on the left and right center CL of the fuselage 11 when viewed from above in the support frame 17. The measuring device 18 is equipped with a receiving device (not shown) that obtains position information through a satellite positioning system and an inertial measuring device (not shown) that detects the tilt (pitch angle, roll angle) of the fuselage 11.

[0041] [Structure near the gearbox]

[0042] like Figure 1 As shown, a gearbox 20 is supported at the front of the body 11, and the right and left front wheels 1 are supported in the front axle box 21 connected to the right and left sides of the gearbox 20. A rear axle box 22 is supported at the rear of the body 11, and the right and left rear wheels 2 are supported in the rear axle box 22.

[0043] like Figure 1 and Figure 3 As shown, an engine 23 is supported at the front of the gearbox 20. A hydrostatic continuously variable transmission (CVT) 24 is connected to the left side of the gearbox 20, and the power of the engine 23 is transmitted to the input shaft 24a of the CVT 24 via a drive belt 25.

[0044] The continuously variable transmission 24 is configured to continuously shift between the neutral position, the forward side, and the reverse side, and is operated by the gear lever 30 located on the left side of the steering wheel 14.

[0045] [Structure of a driving transmission system with front and rear wheel drive]

[0046] like Figure 3 As shown, a pump 26 is connected to the transverse side of the right side of the gearbox 20, and the pump 26 supplies working oil to the hydraulic cylinder 4. The input shaft 24a of the continuously variable transmission 24 enters the gearbox 20, and a drive shaft 27 is connected across the input shaft 26a of the pump 26 and the input shaft 24a of the continuously variable transmission 24.

[0047] Inside the gearbox 20, drive shafts 28 and 29 are supported along the left-right direction, and the output shaft 24b of the continuously variable transmission 24 is connected to the end of the drive shaft 28. Inside the gearbox 20, a gear-type auxiliary transmission device 31 is provided across the drive shafts 28 and 29.

[0048] The auxiliary transmission device 31 includes a low-speed gear 32 and a high-speed gear 33 connected to the drive shaft 28; and a shift gear 34 externally mounted on the drive shaft 29 via a splined structure, allowing it to rotate and slide as a single unit. The shift gear 34 can be slidably operated via an auxiliary shift lever (not shown) located near the driver's seat 13.

[0049] In the auxiliary transmission device 31, when the transmission gear 34 meshes with the low-speed gear 32, the power of the drive shaft 28 is transmitted to the drive shaft 29 at a low speed. When the transmission gear 34 meshes with the high-speed gear 33, the power of the drive shaft 28 is transmitted to the drive shaft 29 at a high speed. Here, when planting in the field, the auxiliary transmission device 31 is operated to a low speed, and when traveling at high speed on the road, the auxiliary transmission device 31 is operated to a high speed.

[0050] The right and left front axles 35, which transmit power to the right and left front wheels 1, are supported across the gearbox 20 and the front axle box 21. A front wheel differential 36 is provided between the right and left front axles 35. A transmission gear 37 connected to the drive shaft 29 meshes with a transmission gear 38 connected to the housing 36a of the front wheel differential 36.

[0051] An output shaft 39 is supported at the rear of the gearbox 20 along the longitudinal direction. A bevel gear 40 connected to the front wheel differential 36a meshes with a bevel gear 39a formed at the front of the output shaft 39.

[0052] like Figure 1 and Figure 3 As shown, a drive shaft 41 is connected to the rear of the output shaft 39 via a universal joint (not shown), and the rear of the drive shaft 41 is connected to the input shaft (not shown) of the rear axle box 22 via a universal joint (not shown).

[0053] Through the above structure, the power after being shifted by the continuously variable transmission (CVT) 24 is transmitted from the output shaft 24b of the CVT 24 to the right and left front wheels 1 via the drive shaft 28, the auxiliary transmission 31, the drive shaft 29, the transmission gears 37 and 38, the front wheel differential 36, and the front axle 35. Furthermore, the power transmitted to the front wheel differential 36 is transmitted to the right and left rear wheels 2 via the bevel gear 40, the output shaft 39 (bevel gear 39a), the drive shaft 41, and the drive shaft (not shown) inside the rear axle box 22.

[0054] A multi-plate brake 42 is embedded outside the output shaft 39, which, through the... Figure 2 When the brake pedal 43 is pressed, the brake 42 can be operated to the braking state. By applying braking to the output shaft 39 through the brake 42, the front wheel 1 and the rear wheel 2 can be braked.

[0055] [Structure of the transmission system for powering the seedling transplanting device]

[0056] like Figure 4 As shown, a hydrostatic planting spacing changer 45 (an example of the "continuously variable transmission" of the present invention) is connected to the transverse portion on the right side of the gearbox 20. The input shaft 45a of the planting spacing changer 45 and the drive shaft 28 are connected to it. The input shaft 45a of the planting spacing changer 45 protrudes to the opposite side of the gearbox 20, and a fan 46 that supplies cooling air to the planting spacing changer 45 is connected to the protrusion of the input shaft 45a of the planting spacing changer 45.

[0057] Inside the gearbox 20, drive shafts 47 and 48 are supported along the left and right directions, and the output shaft 45b of the plant spacing speed change device 45 is connected to the end of the drive shaft 47.

[0058] The plant spacing is obtained by means of settings set by the operator, and the speed change shaft 45c is rotated by a control device (not shown) and an actuator (not shown), thereby operating the plant spacing speed change device 45 to the forward side, the backward side, and the neutral side.

[0059] A cylindrical drive shaft 49 is rotatably mounted on the outside of a drive shaft 47 via needle roller bearings. A drive gear 50, equipped with two sets of gears, is rotatably mounted on the outside of a drive shaft 48 via bearings. The drive gear 47a formed on the drive shaft 47 meshes with the large-diameter gear portion of the drive gear 50, and the drive gear 51 connected to the drive shaft 49 meshes with the small-diameter gear portion of the drive gear 50.

[0060] Inside the gearbox 20, a gear-type variable speed transmission device 52 is provided across the drive shafts 48 and 49, and a bevel gear 53 is connected to the drive shaft 48. An output shaft 54 ​​is supported at the rear of the gearbox 20 along the longitudinal direction, and a bevel gear 55 is externally engaged at the front of the output shaft 54 ​​via an insert clutch 56, with the bevel gears 53 and 55 meshing.

[0061] like Figure 4 As shown, the non-uniform speed transmission device 52 includes a constant speed gear 58 and a non-uniform speed gear 59 connected to the transmission shaft 49, and a constant speed gear 60 and a non-uniform speed gear 61 externally embedded in the transmission shaft 48 in a manner that allows them to rotate relative to each other. The constant speed gears 58 and 60 mesh, and the non-uniform speed gears 59 and 61 mesh.

[0062] The key-shaped transmission component 62 is slidably supported inside the transmission shaft 48. By sliding the transmission component 62, it can engage with one of the constant speed gear 60 and the non-constant speed gear 61, so that the constant speed gear 60 or the non-constant speed gear 61 engaged with the transmission component 62 can be connected to the transmission shaft 48.

[0063] The constant velocity gears 58 and 60 are circular gears of the same diameter. Therefore, when the transmission component 62 engages with the constant velocity gear 60, the power for one rotation of the transmission shaft 49 is transmitted to the transmission shaft 48 at a constant angular velocity.

[0064] The unequal speed gears 59 and 61 are elliptical gears, eccentric gears, or non-circular gears. Thus, when the transmission component 62 is engaged with one of the unequal speed gears 61, the power of one rotation of the transmission shaft 49 is transmitted to the transmission shaft 48 as the power of one rotation, but the angular velocity during one rotation will vary.

[0065] like Figure 1 and Figure 4 As shown, a drive shaft 57 is connected to the rear of the output shaft 54 ​​via a universal joint (not shown), and the rear of the drive shaft 57 is connected to the input shaft (not shown) of the seedling transplanting device 5 via a universal joint (not shown).

[0066] Through the above structure, the power after being changed by the continuously variable transmission 24 is transmitted from the output shaft 24b of the continuously variable transmission 24 to the plant spacing transmission 45 via the transmission shaft 28 and the input shaft 45a of the plant spacing transmission 45.

[0067] The power after being changed by the plant spacing speed changer 45 is transmitted from the output shaft 45b of the plant spacing speed changer 45 through the transmission shaft 47 (transmission gear 47a), transmission gears 50, 51, transmission shaft 49, non-uniform speed changer 52, transmission shaft 48, bevel gears 53, 55, planting clutch 56, output shaft 54, and transmission shaft 57 to the seedling planting device 5.

[0068] When the planting clutch 56 is operated to the transmission state, power is transmitted to the seedling planting device 5, and the seedling planting device 5 works.

[0069] When the seedling transplanting device 5 is working, such as Figure 2 As shown, as the seedling carrier 10 is driven by reciprocating lateral feed, the rotating box 7 moves in the direction of... Figure 5 Driven by a counter-clockwise rotation, the two sets of planting arms 8 alternately remove seedlings from the lower part of the seedling tray 10 and plant them on the field surface. Thus, as... Figure 5 As shown, along the direction of travel of the machine 11, the seedlings are intermittently planted on the field surface at a preset plant spacing.

[0070] When the planting clutch 56 is operated to the disengaged state, the power transmitted to the seedling planting device 5 is cut off, the seedling planting device 5 stops, and the seedling carrier platform 10 and the rotating box 7 stop.

[0071] [Structure of the plant spacing speed change device]

[0072] like Figure 5 and Figure 6 As shown, the plant spacing speed change device 45 includes an axial piston type and variable capacity hydraulic pump 71, an axial piston type hydraulic motor 72, and a closed circuit 73 connecting the hydraulic pump 71 and the hydraulic motor 72.

[0073] The closed circuit 73 connecting the hydraulic pump 71 and the hydraulic motor 72 includes: a high-pressure side oil passage 73H, which supplies pressurized oil from the hydraulic pump 71 to the hydraulic motor 72; and a low-pressure side oil passage 73L, which supplies pressurized oil from the hydraulic motor 72 to the hydraulic pump 71. A supply circuit 74 for replenishing pressurized oil to the closed circuit 73 is connected across the high-pressure side oil passage 73H and the low-pressure side oil passage 73L.

[0074] The hydraulic pump 71 is driven by power transmitted from the engine 23 via the input shaft 45a. A corresponding amount of pressurized oil, proportional to the swashplate angle of the hydraulic pump 71, is discharged and supplied to the hydraulic motor 72. The hydraulic motor 72 outputs power corresponding to the discharge amount of the hydraulic pump 71.

[0075] The spacing change device 45 is equipped with a pressure reducing section 75 that reduces the pressure of the pressurized oil supplied to the hydraulic motor 72.

[0076] The pressure reducing unit 75 includes: a pressure relief valve 76; a throttle orifice 77; a first oil passage 78 that connects the pressure relief valve 76 and the throttle orifice 77 to the high-pressure side oil passage 73H; and a second oil passage 79 that connects the pressure relief valve 76 to the low-pressure side oil passage 73L.

[0077] When the operating load of the seedling transplanting device 5 increases, causing the pressure of the working oil in the high-pressure side oil circuit 73H to rise above the set value set by the pressure relief valve 76, a portion of the working oil in the high-pressure side oil circuit 73H will flow to the low-pressure side oil circuit 73L via the pressure relief valve 76. Thus, the pressure of the working oil in the high-pressure side oil circuit 73H is adjusted.

[0078] A throttle orifice 77 is located at the end of the first oil passage 78, specifically between the first oil passage 78 and the pressure relief valve 76. The inner diameter of the throttle orifice 77 is smaller than the inner diameter of the first oil passage 78. This structure prevents a rapid drop in the pressure of the working oil in the high-pressure side oil passage 73H from occurring even if the pressure of the working oil in the high-pressure side oil passage 73H increases, causing the pressure relief valve 76 to open.

[0079] [Fan structure]

[0080] like Figure 4 As shown, a fan 46, which supplies cooling air to the spacing transmission mechanism 45, is connected to a protrusion on the input shaft 45a of the spacing transmission mechanism 45. As the input shaft 45a rotates, the fan 46 rotates to generate cooling air. Viewed from above, the fan 46 is located between the front wheel 1 on the right side and the spacing transmission mechanism 45. The spacing transmission mechanism 45 is positioned with its weight offset to the right relative to the left-right center of the machine body 11. Furthermore, the fan 46 is positioned laterally on the outer side of the machine body of the spacing transmission mechanism 45.

[0081] Below the fan 46 is the right front axle box 21. The right front axle box 21 houses the right front axle 35. The right front axle 35 and the right front axle box 21 extend laterally along the engine block. Viewed from above, the left and right front axles 35 are located between the left and right front wheels 1. The right front axle 35 is driven by the rotation of the engine 23, transmitting that power to the right front wheel 1. Figure 4 As shown, when viewed from above, the fan 46 overlaps with the right front axle box 21 and is located above the right front axle box 21.

[0082] like Figure 4 and Figure 7 As shown, the fan 46 has a connecting portion 46A connected to the input shaft 45a, a plurality of blade portions 46B, and a frame portion 46C. Each of the plurality of blade portions 46B extends radially outward from the connecting portion 46A with the input shaft 45a as the center. The frame portion 46C is connected to the outer periphery of the plurality of blade portions 46B and surrounds the plurality of blade portions 46B from the outer periphery.

[0083] In the rice transplanter of this embodiment, a seedling planting device 5 is supported at the rear of the linkage mechanism 3. A ditching machine, weeding machine, or similar device can be attached to the rear of the linkage mechanism 3 to replace the seedling planting device 5. Therefore, the rice transplanter of this embodiment can also be used as a ditching and weeding machine.

[0084] If a ditching machine or weeding machine is installed at the rear of the linkage mechanism 3, and the rice transplanter is used as a ditching and weeding machine, it is possible that excessively tall seedlings and straw will be drawn into the fan 46 and wrapped around the input shaft 45a. If this happens, the input shaft 45a may be difficult to rotate, and the operating efficiency of the plant spacing speed change device 45 will be reduced.

[0085] like Figure 4 and Figure 7 As shown, in this embodiment, the frame portion 46C surrounds a plurality of blade portions 46B from the outer periphery. The width of the frame portion 46C in the left-right direction is wider than the width of the blade portions 46B in the left-right direction. In other words, the width of the frame portion 46C in the axial direction of the input shaft 45a is configured to be wider than the width of each of the plurality of blade portions 46B in the axial direction of the input shaft 45a. Therefore, the blade portions 46B in the direction of the rotation axis of the fan 46 are covered by the frame portion 46C across the entire width. With this structure, compared with a structure without the frame portion 46C, even if seedlings or straw come into contact with the frame portion 46C, the seedlings or straw will not be caught in the blade portions 46B and are less likely to become entangled in the input shaft 45a.

[0086] Furthermore, by having a frame 46C in the fan 46, even if it is difficult to install a cover due to the space occupied by the components around the fan 46, the fan 46 alone can achieve a structure that prevents seedlings and straw from getting tangled.

[0087] [Another implementation method]

[0088] The following example illustrates another implementation that modifies the above-described implementation.

[0089] (1) In the above embodiment, the structure in which the pressure reducing unit 75 is equipped with a pressure relief valve 76 and a throttle orifice 77 has been described as an example, but the present invention is not limited to the above embodiment. For example, the pressure reducing unit 75 may be configured to have an accumulator that reduces the pressure of the pressure oil supplied to the hydraulic motor 72 instead of the pressure relief valve 76. In this case, the accumulator may be configured to be connected to the high-pressure side oil circuit 73H via the throttle orifice.

[0090] (2) In the above embodiment, the structure of the pressure relief valve 76 connected to the high-pressure side oil circuit 73H and the low-pressure side oil circuit 73L was described as an example, but the present invention is not limited to the above embodiment. For example, it may also be configured such that the pressure relief valve 76 is connected to an oil circuit different from the low-pressure side oil circuit 73L.

[0091] (3) In the above embodiment, the structure in which the pressure reducing part 75 is equipped with a throttle hole 77 is described as an example. However, the present invention is not limited to the above embodiment, and may also be configured such that the pressure reducing part 75 is not equipped with a throttle hole 77.

[0092] (4) In the above embodiment, the structure in which the throttle orifice 77 is provided in the first oil passage 78 is described as an example. However, the present invention is not limited to the above embodiment and may also be configured to have the throttle orifice 77 provided in the second oil passage 79.

[0093] (5) In the above embodiment, the structure of the plant spacing transmission device 45 equipped with a pressure reducing unit 75 was described as an example. However, the present invention is not limited to the above embodiment. It can also be configured such that the pressure reducing unit 75 is equipped in the continuously variable transmission device 24 that changes the speed of the power from the engine 23 and transmits it to the right and left front wheels 1 and rear wheels 2. With this structure, when the load of the continuously variable transmission device 24 changes due to the unevenness of the ground, the continuously variable transmission device 24 can reduce the situation where the pressure of the working oil in the high-pressure side oil circuit increases.

[0094] (6) In the above embodiment, the structure of the plant spacing transmission device 45 that transmits power to the seedling planting device 5 equipped with a pressure relief valve 76 and a throttling orifice 77 was described as an example, but the present invention is not limited to the above embodiment. For example, the present invention can also be applied to rice transplanters equipped with operating devices other than the seedling planting device 5, and can also be applied to agricultural machinery such as combine harvesters and tractors, construction machinery, etc.

[0095] It should be noted that the structures disclosed in the above-described embodiments (including another embodiment, hereinafter the same) can be combined with structures disclosed in other embodiments as long as there is no conflict. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the purpose of the present invention.

[0096] Industrial availability

[0097] This invention can be used not only in rice transplanters, but also in combine harvesters, tractors, construction machinery and other work vehicles that transmit power from a continuously variable transmission (CVT) to the work device.

[0098] Explanation of reference numerals in the attached figures

[0099] 5: Seedling transplanting device; 23: Engine; 24: Continuously variable transmission (CVT); 26: Pump; 45: Plant spacing variable transmission (CVT); 71: Hydraulic pump; 72: Hydraulic motor; 73H: High-pressure side oil circuit; 73L: Low-pressure side oil circuit; 75: Pressure reducing unit; 76: Pressure relief valve; 77: Throttling orifice; 78: First oil circuit; 79: Second oil circuit.

Claims

1. A rice transplanter, characterized in that, have: The seedling transplanting device is used to transplant seedlings into the field; and A hydrostatic continuously variable transmission (CVT) consists of a hydraulic pump that transmits power from the engine and a hydraulic motor that outputs power. The continuously variable transmission has the following features: The high-pressure side oil circuit supplies pressurized oil from the hydraulic pump to the hydraulic motor; and The low-pressure side oil circuit supplies pressurized oil from the hydraulic motor to the hydraulic pump. The continuously variable transmission is equipped with a pressure reducing unit, which is connected to the high-pressure side oil circuit to reduce the pressure of the pressure oil supplied to the hydraulic motor.

2. The rice transplanter according to claim 1, characterized in that, The pressure-reducing section has a pressure relief valve.

3. The original text of claim 3 of the basic application is adopted. The rice transplanter according to claim 2 is characterized in that, The pressure relief valve is connected to the high-pressure side oil circuit and the low-pressure side oil circuit.

4. The rice transplanter according to claim 3, characterized in that, The pressure-reducing section has: The first oil circuit connects the high-pressure side oil circuit to the pressure relief valve; and The second oil circuit connects the pressure relief valve to the low-pressure side oil circuit. A throttling orifice is provided in either the first oil passage or the second oil passage.

5. The rice transplanter according to claim 4, characterized in that, The throttle orifice is provided in the first oil passage. The inner diameter of the throttling orifice is smaller than the inner diameter of the first oil passage.

6. The rice transplanter according to claim 1, characterized in that, The pressure reducing unit includes an accumulator that reduces the pressure of the hydraulic oil supplied to the hydraulic motor. The accumulator is connected to the high-pressure side oil circuit via a throttle orifice.

7. The rice transplanter according to claim 1, characterized in that, The continuously variable transmission (CVT) is a device that changes the speed of the power from the engine and transmits it to the spacing of the seedlings in the transplanting device.

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