Rice transplanter

Abstract

To restrain a failure of a control valve by restraining rapid pressure fluctuations of hydraulic oil in a hydraulic cylinder in a rice transplanter.SOLUTION: A rice transplanter 1 comprises: a machine body 10; a planting device 20 for seedlings; a link mechanism 14 supporting the planting device 20 displaceably in a vertical direction with respect to the machine body 10; a hydraulic cylinder 15 having an oil chamber 51 to which hydraulic oil is supplied, and for applying a force for displacing the planting device 20, to the link mechanism 14; a hydraulic pump 61 for supplying the hydraulic oil to the oil chamber 51 via a hydraulic pipe 62; a control valve 63 for switching a flow direction of the hydraulic oil in the hydraulic pipe 62; and an accumulator 64 made to communicate with the oil chamber 51. The accumulator 64 is directly connected to the hydraulic cylinder 15, and protrudes in a horizontal direction from the hydraulic cylinder 15.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a rice transplanter. [Background technology]

[0002] For example, as shown in Patent Document 1, a rice transplanter equipped with a planting device that plants seedlings placed on a seedling carrier into the surface of a rice field is known. In the rice transplanter, the planting device is supported on the machine body via a link mechanism so as to be displaceable in the vertical direction. The planting device is displaced in the vertical direction by changing the position of the link mechanism using a hydraulic cylinder.

[0003] Conventional planting devices widely adopt a configuration in which an elastic member such as a compression spring is interposed between the link mechanism and the hydraulic cylinder. When the planting device collides with an obstacle such as a stone and is suddenly displaced in the vertical direction, the displacement is absorbed by the elastic member. The planting device suppresses sudden pressure fluctuations of the hydraulic oil in the oil chamber inside the hydraulic cylinder by the elastic member. With such a configuration, conventional rice transplanters suppress failure of the control valve that supplies hydraulic oil to the hydraulic cylinder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-40811 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional structure that absorbs the displacement of the planting device by the elastic member has a limit to the amount of displacement that can be absorbed, and there are cases where it is not possible to suppress sudden pressure fluctuations of the hydraulic oil in the hydraulic cylinder. For this reason, it is difficult to reliably prevent failure of the control valve in the conventional rice transplanter.

[0006] The present disclosure aims to suppress sudden pressure fluctuations of hydraulic oil in a hydraulic cylinder and suppress failure of a control valve in a rice transplanter. [Means for solving the problem]

[0007] The working machine disclosed herein is a rice transplanter comprising a machine body, a seedling planting device, a link mechanism supporting the planting device so as to be displaceable in the vertical direction relative to the machine body, a hydraulic cylinder having an oil chamber to which hydraulic oil is supplied and applying a force to the link mechanism to displace the planting device, a hydraulic pump supplying hydraulic oil to the oil chamber via hydraulic piping, a control valve switching the flow direction of the hydraulic oil in the hydraulic piping, and an accumulator communicating with the oil chamber. The accumulator is directly attached to the hydraulic cylinder and protrudes horizontally from the hydraulic cylinder. Effect of the Invention

[0008] According to the present disclosure, in a rice transplanter, sudden pressure fluctuations of hydraulic oil in a hydraulic cylinder can be suppressed, and failure of a control valve can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a left side view showing a rice transplanter according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a partial perspective view showing the configuration around the link mechanism. [Diagram 3] FIG. 3 is a partial perspective view showing the configuration around the hydraulic cylinder. [Figure 4] FIG. 4 is a hydraulic circuit diagram relating to the hydraulic cylinder. [Diagram 5] FIG. 5 is a partial plan view showing the link mechanism and the hydraulic cylinder and their surroundings. [Figure 6] FIG. 6 is a partial rear view showing the link mechanism and the hydraulic cylinder and their surroundings. [Figure 7] FIG. 7 is a partial perspective view showing a connecting structure between a piston rod and a bracket. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Overview of the embodiment of the present disclosure> Below, an overview of the embodiments of the present disclosure will be listed and described. (1) The rice transplanter disclosed herein comprises a machine body, a seedling planting device, a link mechanism that supports the planting device so as to be displaceable in the vertical direction relative to the machine body, a hydraulic cylinder having an oil chamber to which hydraulic oil is supplied and that applies a force to the link mechanism to displace the planting device, a hydraulic pump that supplies hydraulic oil to the oil chamber via a hydraulic piping, a control valve that switches the flow direction of the hydraulic oil in the hydraulic piping, and an accumulator that is connected to the oil chamber. The accumulator is directly attached to the hydraulic cylinder and protrudes horizontally from the hydraulic cylinder.

[0011] According to the rice transplanter of the above configuration, when the planting device comes into contact with an obstacle in the field and is suddenly displaced vertically, the pressure fluctuation of the hydraulic oil that occurs in the oil chamber of the hydraulic cylinder due to the displacement can be reliably absorbed by the accumulator. This makes it possible to suppress failure of the control valve caused by the sudden pressure fluctuation of the hydraulic oil. Furthermore, the rice transplanter of the above configuration can reduce the number of hydraulic parts by directly mounting the accumulator to the hydraulic cylinder. Furthermore, the rice transplanter of the above configuration can avoid a reduction in the minimum ground clearance caused by the installation of the accumulator by providing the accumulator to protrude horizontally.

[0012] (2) In the rice transplanter according to the embodiment of (1), it is preferable that the hydraulic cylinder includes a cylinder having the oil chamber, the cylinder includes a port communicating with the oil chamber, the port protruding radially outward from the outer peripheral surface of the cylinder, and the accumulator is connected to the port oriented horizontally. In the rice transplanter having the above-described configuration, the accumulator can be easily attached directly to the hydraulic cylinder by utilizing the port.

[0013] (3) In the rice transplanter according to the embodiment (2), it is preferable that the port includes a first connection port to which the accumulator is connected and a second connection port to which the hydraulic piping is connected. According to the rice transplanter having such a configuration, the accumulator and the hydraulic piping can be connected to one port, which simplifies the hydraulic cylinder and the hydraulic piping and reduces the number of parts that make up the hydraulic circuit.

[0014] (4) In the rice transplanter of the embodiment (3), it is preferable that a first central axis of the first connection port is perpendicular to the axial direction of the cylinder, and a second central axis of the second connection port is parallel to the axial direction of the cylinder. According to a rice transplanter having such a configuration, the hydraulic piping configuration around the hydraulic cylinder can be simplified.

[0015] (5) In the rice transplanter according to any one of the embodiments (1) to (4), the oil chamber includes a first oil chamber to which hydraulic oil is supplied when the planting device is displaced upward, and a second oil chamber to which hydraulic oil is supplied when the planting device is displaced downward, and it is preferable that the accumulator is connected to the first oil chamber. With this type of rice transplanter, when the planting device is suddenly displaced vertically, the pressure fluctuation of the hydraulic oil that occurs in the first oil chamber of the hydraulic cylinder due to the displacement can be reliably absorbed by the accumulator, thereby reliably preventing the failure of the control valve caused by the sudden pressure fluctuation of the hydraulic oil.

[0016] (6) In the rice transplanter according to any one of the embodiments (1) to (5), the hydraulic cylinder includes a piston and a piston rod extending in the axial direction of the piston, the piston rod being connected to the link mechanism, the link mechanism further including a bracket to which the piston rod is connected, and the piston rod and the bracket preferably have a connecting structure in which their relative positions do not change when they are connected to each other. The rice transplanter having the above-mentioned configuration can regulate the lower limit position of the planting device with a simple configuration that omits the elastic member. This also makes it possible to omit a mechanism for regulating the lower limit position of the planting device. Furthermore, with this configuration, the rice transplanter having the above-mentioned configuration can ensure a space on the side of the hydraulic cylinder that allows the accumulator to protrude horizontally.

[0017] (7) In the rice transplanter of the form (6), the hydraulic cylinder includes a first oil chamber to which hydraulic oil is supplied when the piston rod is shortened, and a second oil chamber to which hydraulic oil is supplied when the piston rod is extended, and it is preferable that the accumulator is connected to the first oil chamber. With this type of rice transplanter, when the planting device is suddenly displaced vertically, the pressure fluctuation of the hydraulic oil that occurs in the first oil chamber of the hydraulic cylinder due to the displacement can be reliably absorbed by the accumulator, thereby reliably preventing the failure of the control valve caused by the sudden pressure fluctuation of the hydraulic oil.

[0018] <Details of the embodiment of the present disclosure> Hereinafter, the details of the embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any combination.

[0019] (Overall configuration of the rice transplanter) Fig. 1 is a left side view showing a rice transplanter according to an embodiment of the present disclosure. Fig. 2 is a partial perspective view showing the configuration around the link mechanism. Figs. 1 and 2 show a rice transplanter 1 which is an embodiment of the rice transplanter according to the present disclosure. The rice transplanter 1 shown in Figs. 1 and 2 includes a machine body 10 and a planting device 20.

[0020] The machine body 10 includes a pair of front and rear wheels 11 and 12, a driver's seat 13, a link mechanism 14, a hydraulic cylinder 15, a bonnet 16, and a prime mover E. The prime mover E is housed inside the bonnet 16. The rice transplanter 1 shown in this embodiment is a riding type rice transplanter. In the following description, the direction toward the front of the operator seated in the driver's seat 13 is referred to as the front of the rice transplanter 1, and the direction toward the rear is referred to as the rear, and the front-rear direction of the rice transplanter 1 is indicated by an arrow X. In addition, in the following description, the direction toward the left side of the operator seated in the driver's seat 13 is referred to as the left side of the rice transplanter 1, and the direction toward the right side is referred to as the right side of the rice transplanter 1, and the left-right direction of the rice transplanter 1 is indicated by an arrow Y. The left-right direction of the rice transplanter 1 is also referred to as the width direction. Furthermore, in the following description, the up-down direction of the rice transplanter 1 is indicated by an arrow Z. The up-down direction of the rice transplanter 1 is also referred to as the height direction. The up-down direction of the rice transplanter 1 is perpendicular to the front-rear direction and the left-right direction.

[0021] The machine body 10 runs under the operation of an operator seated in a driver's seat 13. The front wheels 11 and the rear wheels 12 are rotated by the power generated by a prime mover E. The rice transplanter 1 may be configured to be remotely controlled or to run autonomously without requiring an operator to be on board.

[0022] The planting device 20 shown in Fig. 1 is a device that takes out seedlings to be planted in one location from a mat of seedlings (hereinafter referred to as a seedling mat) and plants them in a paddy field G. As shown in Fig. 1, the planting device 20 includes a transmission case 21, an input shaft 22, a rotating case 23, a float 24, and a seedling placement table 25.

[0023] The rice transplanter 1 drives a hydraulic pump (hydraulic pump 61, described later) with power generated by the prime mover E, supplying hydraulic oil to the hydraulic cylinder 15. The hydraulic cylinder 15 expands and contracts by switching between supplying and discharging hydraulic oil with a control valve (control valve 63, described later). The planting device 20 is displaced in the vertical direction in response to deformation of the link mechanism 14 accompanying the expansion and contraction of the hydraulic cylinder 15. The machine body 10 further includes an output shaft (PTO shaft) 17 that outputs the power generated by the prime mover E to the outside of the machine body 10.

[0024] The rice transplanter 1 further includes a fertilizer applicator 18 and a ground leveling device 19. The fertilizer applicator 18 is provided across the rear of the machine body 10 and the planting device 20. The fertilizer applicator 18 is a device that supplies fertilizer to the rice field surface G, and includes a hopper 18a, a feed section 18b, and a blower 18c. The ground leveling device 19 is a device that levels the rice field surface G that has been roughened by the travel of the rice transplanter 1, etc., and is provided below the planting device 20. The ground leveling device 19 includes a support case 19a and a ground leveling body 19b. When power is transmitted to the planting device 20, power is transmitted from the planting device 20 to the ground leveling device 19, the ground leveling body 19b is rotated and the ground leveling body 19b levels the rice field surface G.

[0025] (Link mechanism) The link mechanism 14 shown in Figures 1 and 2 supports the planting device 20 at the rear of the machine body frame 10a constituting the machine body 10 so that the planting device 20 can be displaced in the vertical direction. The link mechanism 14 is composed of a total of four links (joints) connected by a total of four shafts (first shaft S1, second shaft S2, third shaft S3, and fourth shaft S4). One of the four links (joints) constituting the link mechanism 14 is the machine body frame 10a. The machine body frame 10a is a stationary joint in the link mechanism 14. The link mechanism 14 is a four-joint link with one degree of freedom.

[0026] (Hydraulic cylinder) Fig. 3 is a partial perspective view showing the configuration around the hydraulic cylinder. Fig. 4 is a hydraulic circuit diagram related to the hydraulic cylinder. The hydraulic cylinder 15 shown in Figs. 1 to 4 applies a force to the link mechanism 14 to displace the planting device 20. As shown in Figs. 3 and 4, the hydraulic cylinder 15 includes a cylinder 50, an oil chamber 51, a port 52, a piston 53, and a piston rod 54.

[0027] As shown in Fig. 4, the cylinder 50 is cylindrical with a central axis C0 and includes an oil chamber 51 therein. The oil chamber 51 includes a first oil chamber 51a to which hydraulic oil is supplied when the piston 53 and the piston rod 54 are displaced toward the other axial side and the axial length of the hydraulic cylinder 15 is shortened, and a second oil chamber 51b to which hydraulic oil is supplied when the piston 53 and the piston rod 54 are displaced toward one axial side and the axial length of the hydraulic cylinder 15 is extended. In this description, the shortening of the axial length of the hydraulic cylinder 15 is also referred to as "the piston rod 54 is shortened," and the extension of the axial length of the hydraulic cylinder 15 is also referred to as "the piston rod 54 is extended."

[0028] The port 52 is connected to the first oil chamber 51a and is provided so as to protrude radially outward on the outer circumferential surface of the cylinder 50. The piston 53 is configured to be displaceable in the axial direction inside the cylinder 50. The oil chamber 51 formed in the cylinder 50 is partitioned by the piston 53 into a first oil chamber 51a on one axial side and a second oil chamber 51b on the other axial side.

[0029] The port 52 includes a first connection port 52a and a second connection port 52b. The first connection port 52a is a connection port for connecting an accumulator (accumulator 64) described later, and the second connection port 52b is a connection port for connecting a hydraulic pipe (hydraulic pipe 62 described later) connected to a hydraulic pump (hydraulic pump 61 described later). In the port 52, a first central axis C1 of the first connection port 52a is perpendicular to a central axis C0 of the cylinder 50, and a second central axis C2 of the second connection port 52b is parallel to the central axis C0 of the cylinder 50.

[0030] 3 and 4, the piston rod 54 is provided extending from the piston 53 to one side in the axial direction. A male thread 55 is formed at one end of the piston rod 54 in the axial direction. The one end of the piston rod 54 in the axial direction is connected to the link mechanism 14.

[0031] (Hydraulic circuit) The rice transplanter 1 of this embodiment includes a hydraulic circuit 60 shown in Fig. 4. As shown in Fig. 4, the hydraulic circuit 60 includes the hydraulic cylinder 15, a hydraulic pump 61, hydraulic piping 62, a control valve 63, and an accumulator 64.

[0032] The hydraulic pump 61 supplies hydraulic oil to the oil chamber 51 (the first oil chamber 51a and the second oil chamber 51b) through the hydraulic piping 62. The control valve 63 is provided in the hydraulic piping 62 connecting the hydraulic pump 61 and the oil chamber 51, and switches the flow direction of the hydraulic oil in the hydraulic piping 62. The control valve 63 switches between a first state in which the hydraulic pump 61 supplies hydraulic oil to the first oil chamber 51a and discharges hydraulic oil from the second oil chamber 51b, and a second state in which the hydraulic pump 61 supplies hydraulic oil to the second oil chamber 51b and discharges hydraulic oil from the first oil chamber 51a. The accumulator 64 is a device that absorbs pressure fluctuations of the hydraulic oil in the oil chamber 51 and the hydraulic piping 62. The accumulator 64 is connected to the oil chamber 51. The accumulator 64 in this embodiment is connected to the first oil chamber 51a.

[0033] The accumulator 64 includes a container 64a and a bladder (diaphragm) 64b that divides the inside of the container 64a into two spaces. The bladder 64b is made of an elastic member that can expand and contract, for example, rubber. The accumulator 64 includes a pressure accumulator chamber 64c formed inside the bladder 64b, and a pressure chamber 64d formed between the container 64a and the bladder 64b. The pressure accumulator chamber 64c is filled with a gas (for example, nitrogen) adjusted to a desired pressure P. When hydraulic oil with a pressure higher than the pressure P flows from the hydraulic pipe 62 into the pressure chamber 64d, the gas in the bladder 64b is compressed and the bladder 64b contracts. In other words, the accumulator 64 reduces a sudden pressure rise of the hydraulic oil that occurs in the hydraulic pipe 62 by contracting the bladder 64b. When the pressure in the hydraulic piping 62 drops below pressure P, the gas in the bladder 64b expands and the bladder 64b also expands, thereby discharging the hydraulic oil in the pressure chamber 64d to the hydraulic piping 62. The accumulator 64 relieves the pressure drop of the hydraulic oil that occurs in the hydraulic piping 62 by expanding the bladder 64b. The accumulator 64 can arbitrarily set the magnitude of the pressure fluctuation of the hydraulic oil that can be absorbed by adjusting the specifications of the container 64a and the bladder 64b, the pressure P of the gas sealed in the pressure accumulator chamber 64c, etc. Therefore, by using the accumulator 64, it is possible to reliably absorb the pressure fluctuation of the hydraulic oil that occurs when the planting device 20 is suddenly displaced in the vertical direction. The configuration of the accumulator 64 provided in the rice transplanter 1 of the present disclosure is not limited to the configuration of this embodiment, and may be configured to absorb the pressure fluctuation of the hydraulic oil using an elastic member such as a compression spring, for example.

[0034] (Control device) The rice transplanter 1 of this embodiment is equipped with a control device 70 shown in Fig. 4. As shown in Fig. 4, the control device 70 is connected to the control valve 63. The control device 70 is connected to an operation unit 71 for operating the planting device 20 arranged near the driver's seat 13 to move the planting device 20 up and down. The operation unit 71 is composed of, for example, an operation switch, an operation lever, etc. The control device 70 switches the position of the valve body of the control valve 63 in response to the operation of the operation unit 71 by the operator, thereby switching the supply and discharge of hydraulic oil to the first oil chamber 51a and the second oil chamber 51b.

[0035] The control device 70 is further connected to a float 24 provided on the planting device 20. The control device 70 switches the position of the valve body of the control valve 63 in response to the up and down movement of the float 24 in contact with the paddy field surface G, thereby switching the supply and discharge of hydraulic oil to the first oil chamber 51a and the second oil chamber 51b.

[0036] (Link mechanism and hydraulic cylinder configuration) Fig. 5 is a partial plan view showing the link mechanism and the hydraulic cylinder and its surroundings. Fig. 6 is a partial rear view showing the link mechanism and the hydraulic cylinder and its surroundings. Fig. 7 is a partial perspective view showing the connecting structure of the piston rod and the bracket. As shown in Figs. 5 to 7, the link mechanism 14 is connected to the piston rod 54 of the hydraulic cylinder 15.

[0037] In the rice transplanter 1 of this embodiment, the planting device 20 is displaced upward by the deformation of the link mechanism 14 accompanying the shortening of the piston rod 54, and is displaced downward by the deformation of the link mechanism 14 accompanying the extension of the piston rod 54. In other words, the first oil chamber 51a is supplied with hydraulic oil when the planting device 20 is displaced upward. The second oil chamber 51b is supplied with hydraulic oil when the planting device 20 is displaced downward. The accumulator 64 is connected to the first oil chamber 51a to which hydraulic oil is supplied when the planting device 20 is displaced upward. The first oil chamber 51a is the oil chamber 51 to which hydraulic oil is supplied when the piston rod 54 is shortened.

[0038] For example, when attempting to place the accumulator 64 in a position close to the rear end of the machine body 10, the machine body frame 10a and the like get in the way, making it difficult to secure the space to place the accumulator 64. In the rice transplanter 1 of this embodiment, the accumulator 64 is connected to the first oil chamber 51a. In this case, the accumulator 64 is placed on the rear end side (one axial side) of the cylinder 50. With this configuration, it becomes possible to place the accumulator 64 in a position sufficiently away from the rear end of the machine body 10, making it easy to secure the space to install the accumulator 64.

[0039] (Installation status of accumulator) As shown in Figures 5 and 6, the accumulator 64 of this embodiment is directly attached to the outer peripheral surface of the hydraulic cylinder 15 (cylinder 50) and protrudes horizontally from the hydraulic cylinder 15. The accumulator 64 of this embodiment protrudes to the left of the machine body 10. The accumulator 64 of this embodiment is connected to a port 52 protruding horizontally from the outer peripheral surface of the hydraulic cylinder 15. Note that in the rice transplanter 1 of the present disclosure, the accumulator 64 may be directly attached to the outer peripheral surface of the hydraulic cylinder 15 (cylinder 50) without going through the port 52.

[0040] (About port configuration) As shown in FIG. 5, the port 52 includes a first connection port 52a to which the accumulator 64 is connected and a second connection port 52b to which the hydraulic piping 62 is connected. Therefore, the port 52 can connect the accumulator 64 and the hydraulic piping 62 together at one location. By adopting the port 52 having such a configuration, the rice transplanter 1 of this embodiment does not need to provide separate ports for the accumulator 64 and the hydraulic piping 62 in the hydraulic cylinder 15, and the configuration of the hydraulic cylinder 15 itself can be simplified. In addition, by adopting the port 52 having such a configuration, the rice transplanter 1 of this embodiment does not need the hydraulic piping 62 for connecting the accumulator 64, and therefore the configuration of the hydraulic piping 62 around the hydraulic cylinder 15 can be simplified. Furthermore, in the rice transplanter 1 of this embodiment, the central axis C2 of the second connection port 52b is parallel to the central axis C0 of the hydraulic cylinder 15, so that the hydraulic piping 62 connected to the second connection port 52b can be arranged along the hydraulic cylinder 15. By employing a port 52 having such a configuration, the hydraulic piping 62 can be easily arranged, and the configuration of the hydraulic circuit 60 around the hydraulic cylinder 15 can be simplified.

[0041] (Connecting structure of piston rod and link mechanism) As shown in Fig. 7, the link mechanism 14 includes a bracket 14a to which a piston rod 54 is connected. The bracket 14a includes a hole (not shown) through which the piston rod 54 can be inserted. The piston rod 54 has an external thread 55 formed at one axial end thereof into which a nut 56 can be screwed. The external thread 55 is inserted into the hole formed in the bracket 14a. The external thread 55 is inserted into the hole with the nut 56 screwed into the hole toward the other axial end, and then the nut 56 is further screwed into the hole from the one axial end.

[0042] The piston rod 54 and the bracket 14a are connected to each other by clamping the bracket 14a from both axial sides with two nuts 56 screwed onto male threads 55. In this manner, the connecting portion of the piston rod 54 and the bracket 14a has a connecting structure J including the piston rod 54, the male threads 55, the bracket 14a, and the nuts 56. The connecting structure J is a structure that connects the piston rod 54 and the bracket 14a without interposing an elastic member between the piston rod 54 and the bracket 14a. For this reason, the piston rod 54 and the bracket 14a having the connecting structure J do not change in relative position when they are connected to each other.

[0043] (Effects of installing an accumulator) When an external force that suddenly raises or lowers the planting device 20 acts while the rice transplanter 1 is traveling, the external force is transmitted to the hydraulic cylinder 15 via the link mechanism 14. In this case, a sudden pressure fluctuation occurs in the hydraulic oil in the oil chamber 51, which may cause a failure of the control valve 63. In the rice transplanter 1 of this embodiment, the accumulator 64 can reliably absorb such a sudden pressure fluctuation of the hydraulic oil in the oil chamber 51.

[0044] In conventional rice transplanters, for example, an elastic member such as a compression spring is interposed between the piston rod 54 and the bracket 14a, and the control valve is protected by absorbing sudden external forces acting on the planting device 20 with the elastic member. In such a conventional configuration, there is a limit to the magnitude of external forces that can be absorbed by the elastic member, making it difficult to handle larger external forces. The rice transplanter 1 of this embodiment can handle larger external forces because the accumulator 64 absorbs sudden pressure fluctuations of the hydraulic oil in the oil chamber 51.

[0045] In addition, in the conventional rice transplanter, in order to regulate the lower limit position of the planting device 20, it was necessary to separately provide a regulating member that regulates the extension of the elastic member. When a method using the accumulator 64 is adopted as in the rice transplanter 1 of this embodiment, the installation of the elastic member between the piston rod 54 and the bracket 14a can be omitted. Furthermore, in the rice transplanter 1 of this embodiment, the piston rod 54 and the bracket 14a have a connecting structure J, and the relative positions do not change when they are connected to each other. For this reason, the rice transplanter 1 of this embodiment does not need to be provided with a regulating member for regulating the extension of the elastic member. And, in the rice transplanter 1 of this embodiment, the regulating member is omitted, and the space vacated by the omission can be used to secure a space in which the accumulator 64 can protrude horizontally. As a result, in the rice transplanter 1 of this embodiment, the accumulator 64 can be provided so as to protrude horizontally from the hydraulic cylinder 15. In this case, the installed accumulator 64 does not become a factor that deteriorates the minimum ground clearance of the rice transplanter 1.

[0046] Furthermore, in the rice transplanter 1 of this embodiment, by directly attaching the accumulator 64 to the hydraulic cylinder 15, the amount of hydraulic piping 62 required to install the accumulator 64 can be reduced to "0". This makes it possible to reduce the amount of hydraulic piping 62 provided around the hydraulic cylinder 15 and reduce the number of parts that make up the hydraulic circuit 60.

[0047] <Actions and Effects of the Present Embodiment> (1) The rice transplanter 1 of the above embodiment includes a machine body 10, a seedling planting device 20, a link mechanism 14 that supports the planting device 20 so as to be displaceable in the vertical direction relative to the machine body 10, a hydraulic cylinder 15 having an oil chamber 51 to which hydraulic oil is supplied and that applies a force to the link mechanism 14 to displace the planting device 20, a hydraulic pump 61 that supplies hydraulic oil to the oil chamber 51 via hydraulic piping 62, a control valve 63 that switches the flow direction of the hydraulic oil in the hydraulic piping 62, and an accumulator 64 that communicates with the oil chamber 51. In the rice transplanter 1 of this embodiment, the accumulator 64 is directly attached to the hydraulic cylinder 15 and protrudes horizontally from the hydraulic cylinder 15.

[0048] In the rice transplanter 1 of the above embodiment, when the planting device 20 comes into contact with an obstacle in the field and is suddenly displaced in the vertical direction, the pressure fluctuation of the hydraulic oil generated in the oil chamber 51 of the hydraulic cylinder 15 due to the displacement can be reliably absorbed by the accumulator 64. This makes it possible to suppress the failure of the control valve 63 caused by the sudden pressure fluctuation of the hydraulic oil. In addition, in the rice transplanter 1 of the present embodiment, the accumulator 64 is directly attached to the hydraulic cylinder, thereby reducing the number of components of the hydraulic circuit 60. In addition, in the rice transplanter 1 of the present embodiment, the accumulator 64 is provided so as to protrude horizontally, so that the installed accumulator 64 does not become a factor that deteriorates the minimum ground clearance.

[0049] (2) In the rice transplanter 1 of the above embodiment, the hydraulic cylinder 15 includes a cylinder 50 having an oil chamber 51. The cylinder 50 includes a port 52 communicating with the oil chamber 51. The port 52 protrudes radially outward from the outer circumferential surface of the cylinder 50. In the rice transplanter 1 of the present embodiment, the accumulator 64 is connected to the port 52 oriented in the horizontal direction. In the rice transplanter 1 of the above embodiment, the accumulator 64 can be easily attached directly to the hydraulic cylinder 15 by utilizing the port 52.

[0050] (3) In the rice transplanter 1 of the above embodiment, the port 52 includes the first connection port 52a to which the accumulator 64 is connected and the second connection port 52b to which the hydraulic pipe 62 is connected. According to the rice transplanter 1 of the above embodiment, the accumulator 64 and the hydraulic piping 62 can be connected to one port 52, thereby simplifying the hydraulic cylinder 15 and the hydraulic piping 62 and reducing the number of parts that make up the hydraulic circuit 60.

[0051] (4) In the above embodiment of the rice transplanter 1, the first central axis C1 of the first connection port 52a is perpendicular to the central axis C0 of the cylinder 50, and the second central axis C2 of the second connection port 52b is parallel to the central axis C0 of the cylinder 50. According to the rice transplanter 1 of the above embodiment, the configuration of the hydraulic piping 62 around the hydraulic cylinder 15 can be simplified.

[0052] (5) In the rice transplanter 1 of the above embodiment, the oil chamber 51 includes a first oil chamber 51a to which hydraulic oil is supplied when the planting device 20 is displaced upward, and a second oil chamber 51b to which hydraulic oil is supplied when the planting device 20 is displaced downward. In the rice transplanter 1 of this embodiment, the accumulator 64 is connected to the first oil chamber 51a. According to the rice transplanter 1 of the above embodiment, when the planting device 20 is suddenly displaced in the vertical direction, the pressure fluctuation of the hydraulic oil generated in the first oil chamber 51a of the hydraulic cylinder 15 due to the displacement can be reliably absorbed by the accumulator 64. This makes it possible to reliably suppress the failure of the control valve 63 caused by the sudden pressure fluctuation of the hydraulic oil.

[0053] (6) In the rice transplanter 1 of the above embodiment, the hydraulic cylinder 15 includes a piston 53 and a piston rod 54 extending in the axial direction of the piston 53, and the piston rod 54 is connected to the link mechanism 14. The link mechanism 14 further includes a bracket 14a to which the piston rod 54 is connected. In the rice transplanter 1 of the present embodiment, the piston rod 54 and the bracket 14a have a connection structure J in which the relative positions of the piston rod 54 and the bracket 14a do not change when they are connected to each other. According to the rice transplanter 1 of the above embodiment, the lower limit position of the planting device 20 can be regulated by a simple configuration that omits the elastic member. This also makes it possible to omit a mechanism for regulating the lower limit position of the planting device 20. Furthermore, with such a configuration, the rice transplanter 1 of the present embodiment can ensure a space on the side of the hydraulic cylinder 15 that allows the accumulator 64 to protrude horizontally.

[0054] (7) In the rice transplanter 1 of the above embodiment, the hydraulic cylinder 15 includes a first oil chamber 51a to which hydraulic oil is supplied when the piston rod 54 is contracted, and a second oil chamber 51b to which hydraulic oil is supplied when the piston rod 54 is extended. In the rice transplanter 1 of this embodiment, the accumulator 64 is connected to the first oil chamber 51a. According to the rice transplanter 1 of the above embodiment, when the planting device 20 is suddenly displaced in the vertical direction, the pressure fluctuation of the hydraulic oil generated in the first oil chamber 51a of the hydraulic cylinder due to the displacement can be reliably absorbed by the accumulator 64. This makes it possible to reliably suppress the failure of the control valve 63 caused by the sudden pressure fluctuation of the hydraulic oil.

[0055] The above-described embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims rather than the above-described embodiment, and includes all modifications within the scope equivalent to the configurations described in the claims. [Explanation of symbols]

[0056] 1 Rice transplanter 10 Aircraft 14 Link mechanism 14a Bracket 15 Hydraulic cylinder 20 Planting equipment 50 cylinders 51 Oil room 51a First oil chamber (first oil chamber) 51b Second oil chamber (Second oil chamber) 52 Port 52a First Connection Port 52b Second connection port 53 Piston 54 Piston rod 61 Hydraulic Pump 62 Hydraulic piping 63 Control valve 64 Accumulator C0 (Cylinder) central axis C1 (First connection port) First central axis C2 (2nd connection port) 2nd central axis J connection structure

Claims

1. The aircraft and A seedling planting device; A link mechanism that supports the planting device so as to be displaceable in the vertical direction relative to the machine body; A hydraulic cylinder having an oil chamber to which hydraulic oil is supplied and applying a force to the link mechanism to displace the planting device; a hydraulic pump for supplying hydraulic oil to the oil chamber via a hydraulic pipe; A control valve that switches the flow direction of hydraulic oil in the hydraulic piping; an accumulator communicating with the oil chamber; A rice transplanter comprising: The rice transplanter, wherein the accumulator is directly attached to the hydraulic cylinder and protrudes horizontally from the hydraulic cylinder.

2. The hydraulic cylinder includes a cylinder having the oil chamber, the cylinder includes a port communicating with the oil chamber, The port protrudes radially outward from an outer circumferential surface of the cylinder, The rice transplanter of claim 1 , wherein the accumulator is connected to the port that is oriented horizontally.

3. The port is a first connection port to which the accumulator is connected; The rice transplanter according to claim 2, further comprising: a second connection port to which the hydraulic piping is connected.

4. a first central axis of the first connection port is perpendicular to an axial direction of the cylinder; The rice transplanter according to claim 3 , wherein a second central axis of the second connection port is parallel to an axial direction of the cylinder.

5. The oil chamber is A first oil chamber to which hydraulic oil is supplied when the planting device is displaced upward; A second oil chamber to which hydraulic oil is supplied when the planting device is displaced downward; Including, The rice transplanter according to claim 1 or 2, wherein the accumulator is connected to the first oil chamber.

6. The hydraulic cylinder is The piston and A piston rod extending in an axial direction of the piston; and the piston rod is connected to the link mechanism, The link mechanism further includes a bracket to which the piston rod is connected, The rice transplanter according to claim 1 or 2, wherein the piston rod and the bracket have a connection structure in which their relative positions do not change when they are connected to each other.

7. The hydraulic cylinder is a first oil chamber to which hydraulic oil is supplied when the piston rod is contracted; a second oil chamber to which hydraulic oil is supplied when the piston rod is extended; Including, The rice transplanter according to claim 6, wherein the accumulator is connected to the first oil chamber.

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