JP2014145301A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work vehicle comprising a hydrostatic gear shift device in which a space part of a valve plate is prevented from being corroded by hydraulic oil emitted from a transfer groove of the valve plate toward the space part in the valve plate.SOLUTION: The block inside of a cylinder 47 in which a hydraulic pump A of a continuously variable transmission (HST) is mounted, the block inside of a cylinder 47 in which a hydraulic motor B is mounted and a port block 71 are connected, respectively, to form hydraulic closed circuits 66, 67. A valve plate 86 is provided which includes space parts 88, 89 for hydraulic closed circuit formation between the port block 71 and the blocks of both the cylinders 47, 47. The valve plate 86 includes a plurality of notches 84 to which oil spouted within the space parts 88, 89 of the valve plate 86 is abutted. Therefore, Energy of a jet stream is weakened by abutting the hydraulic oil with each other, and durability of the HST is improved equal to or more than the prior arts by preventing occurrence of cavitation which may occur when the hydraulic oil is abutted to wall surfaces of the space parts 88, 89.

Description

  The present invention relates to a work vehicle including a hydrostatic hydraulic transmission (HST).

  The valve plate 86 of a hydrostatic continuously variable transmission (HST) generally used for work vehicles has the shape shown in FIG. 16, and as shown in the plan view of the valve plate 86 in FIG. For example, six arc-shaped spaces (long holes) 88 and 89 are provided around the center O of the valve plate 86 on the same circumference. A pair of parallel movement grooves (notches) 84 for facilitating movement of the hydraulic oil during acceleration and deceleration are formed on the wall surface of the valve plate 86 forming the space portions 88 and 89. The two notches 84 can eject hydraulic oil into the arcuate spaces 88 and 89 at a predetermined angle.

  As shown in the enlarged plan view of one space portion 88 portion of the valve plate 86 in FIG. 16B, the hydraulic oil ejected from the two notches 84 into the space portion 88 is the space portion 88 where the notch 84 faces. The valve plate 86 is formed so as to contact the other side adjacent to one side of the wall surface.

  Therefore, two portions on one side of the wall surface of the valve plate 86 forming the space portion 88 that contacts the hydraulic oil sprayed from the pair of notches 84 to the space portion 88 in the valve plate 86 are eroded to form a recess 88a.

Japanese Unexamined Patent Publication No. 2011-103802

  In the work vehicle disclosed in the above-mentioned Patent Document 1, as described above, the two locations 88a and 88a on one side of the space portions 88 and 89 where the oil ejected from the notch 84 to the space portions 88 and 89 in the valve plate 86 is applied. Although eroded, the hydraulic pressure is not so high in the conventional hydrostatic continuously variable transmission of a work vehicle, so the problem has not surfaced.

  However, according to market demands, the number of pistons installed in the hydrostatic continuously variable transmission is reduced as compared with the conventional one while maintaining the power of the hydrostatic continuously variable transmission. The oil discharge amount must be increased, and therefore the degree of erosion of the two portions 88a and 88a on one side of the wall surface forming the space portions 88 and 89 in the valve plate 86 that the hydraulic oil ejected from the two notches 84 hits. Also grows.

  An object of the present invention is to provide a work vehicle equipped with a hydrostatic transmission that prevents the wall surface forming the space portion of the valve plate from being eroded by the hydraulic oil ejected from the notch of the valve plate toward the space portion in the valve plate. Is to provide.

In order to solve the above problems, the present invention uses the following solution means.
According to the first aspect of the present invention, the piston (48) operated by receiving the driving force from the driving source (20) of the traveling vehicle body (2) is connected to the input shaft (74) and the output shaft (75) of the driving force. A piston cylinder (47) built in each of the surroundings and a valve plate (86) formed with a plurality of spaces (88, 89) through which hydraulic oil from and out of the piston cylinder (47) is formed are output to the input shaft (74). The valve plate (86) is provided in a direction orthogonal to the shaft (75), and hydraulic fluid is supplied to the space portions (88, 89) when the output from the piston cylinder (47) is changed. In order to jet together step by step, the jetting angle to the space (88, 89) is such that the jetted hydraulic oil intersects and collides in the space (88, 89). Set at least 2 moving grooves (28) Further comprising providing a hydrostatic continuously variable transmission device (H) is a working vehicle according to claim.

  According to a second aspect of the present invention, the hydrostatic continuously variable transmission (H) includes a plurality of pistons arranged in parallel in conjunction with an input shaft (74) for inputting power from the drive source (20). 48) The hydraulic pump (A) that adjusts the amount and direction of hydraulic oil discharged by the reciprocating motion of the hydraulic pump (A), and the rotation of the output shaft (75) according to the amount of oil discharged and the direction of oil discharge. A hydraulic pump (B) that changes speed and direction, a port block (71) provided in a direction orthogonal to the input shaft (74) and the output shaft (75), and the hydraulic pump (A). The closed piston circuit (47) is connected to the inside of the block of the piston cylinder (47) and the inside of the block of the piston cylinder (47) on the side of the hydraulic motor with the hydraulic motor (B) and the port block (71). (66, 67) And a part of the hydraulic closed circuit (66, 67) is provided inside, between the block of the port block (71) and the piston cylinder (47) on the hydraulic pump side and between the port block (71) and the hydraulic motor side. A valve plate (86) having the space (88, 89) for forming the hydraulic closed circuit is provided between the piston cylinder (47) and the piston plate on the hydraulic pump side (86). 47) and hydraulic oil flowing from the piston cylinder (47) on the hydraulic motor side through the hydraulic closed circuit (66, 67) to the space (88, 89) in accordance with the increase / decrease operation speed. The work vehicle according to claim 1, further comprising a hydrostatic continuously variable transmission (H) provided with at least two moving grooves (84).

  According to the third aspect of the present invention, the space portions (88, 89) of the valve plate (86) are arranged in an annular shape, and an even number of moving grooves (84) reaching the space portions (88, 89) are provided. The even number of moving grooves (84) are provided adjacent to each other in a pair of space portions (88, 89) on a diagonal line passing through the center (O) of a circle formed by the arranged space portions (88, 89), The ejection angle at which the hydraulic oil ejected from the even number of moving grooves (84) joins inside the space (88, 89) before reaching the wall surface forming the space (88, 89) of the valve plate (86) The work vehicle according to claim 2, wherein:

  In the invention according to claim 4, the space portions (88, 89) of the valve plate (86) are arranged in an annular shape, and the moving grooves (84) reaching the space portions (88, 89) have an odd number of three or more. Providing the odd number of moving grooves (84) adjacent to a pair of diagonal spaces (88, 89) passing through the center (O) of a circle formed by the plurality of spaces (88, 89), Before the hydraulic oil ejected from the odd number of moving grooves (84) reaches the valve plate wall surface forming each space portion (88, 89), the ejection angle is set to merge inside each space portion (88, 89). The work vehicle according to claim 2, wherein:

  According to the fifth aspect of the present invention, there is provided a trunnion arm (95) for switching the output of the hydrostatic continuously variable transmission (H) by rotating, a side where the trunnion arm (95) is provided, and a port block (71 ) A through hole (72a) is provided through the case (72) that houses the piston cylinder (47) on the hydraulic pump side and the piston cylinder (47) on the hydraulic motor side that are close to each other. The through hole (72a) has a through hole (72a). The work vehicle according to any one of claims 2 to 4, wherein the first magnetic body (125) is detachably attached, and the second magnetic body (126) is attached to the trunnion arm (95). It is.

  According to the first and second aspects of the present invention, the hydraulic oil is ejected from the plurality of moving grooves 84 formed on the valve plate 86 in accordance with the increase / decrease operation of the traveling speed into the spaces 88 and 89. In addition, by setting the ejection angle of each moving groove 84 to an angle at which the hydraulic oils ejected in the space portions 88 and 89 collide with each other, the hydraulic fluids collide with each other to weaken the momentum of the jets. The durability of the hydrostatic continuously variable transmission H is improved more than before without causing cavitation that may occur when the hydraulic oil collides with the wall surface of the valve plate 86 that forms 88 and 89.

  Further, since the jet of hydraulic oil does not directly hit the wall surface of the valve plate 86 that forms the space portions 88 and 89, the shape of the space portions 88 and 89 can be prevented from changing, and the amount of hydraulic oil ejected can be changed. Without this, the output of the hydrostatic continuously variable transmission is stabilized.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, a pair of diagonal lines passing through the center O of the circle formed by the plurality of space portions 88, 89 arranged annularly on the valve plate 86. An even number of moving grooves 84 are provided adjacent to each other in the spaces 88 and 89, and before the hydraulic oil ejected from the moving grooves 84 reaches the wall surfaces forming the spaces 88 and 89 of the valve plate 86, Since the hydraulic oil jetting angle is set so as to merge inside 89, the hydraulic oil jetting from the moving groove 84 can collide with each other in the space portions 88, 89 to weaken the momentum of the jet. Cavitation that may occur when hydraulic oil collides with the wall surfaces forming the space portions 88 and 89 formed in 86 does not occur, and the durability of the hydrostatic continuously variable transmission H is improved as compared with the prior art.

  In addition, since a plurality of moving grooves 84 are formed, the volume of space necessary for the passage of hydraulic oil can be secured, so that noise and vibration are prevented from occurring when the output of the hydraulic continuously variable transmission H is changed. The operator is less likely to feel discomfort and the operability is improved.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 2, a pair of diagonal lines passing through the center O of the circle formed by the plurality of space portions 88, 89 arranged annularly on the valve plate 86. The wall surface of the valve plate 86 in which three or more odd number of moving grooves 84 are provided adjacent to each other in the space portions 88 and 89, and the hydraulic oil ejected from the odd number of moving grooves 84 forms the space portions 88 and 89. Therefore, the momentum of the jet of hydraulic oil can be weakened, and the hydraulic oil ejected from the odd number of moving grooves 84 can be separated into the spatial portion 88, 88, 89. Cavitation does not occur when hitting the end of 89, and the durability of the hydrostatic pressure continuously variable transmission H is improved over the prior art.

  In addition, since a plurality of moving grooves 84 are formed, it is possible to secure a volume of space necessary for the passage of hydraulic oil, thereby preventing noise and vibration from occurring when the output of the hydrostatic continuously variable transmission H is changed. Therefore, the operator is less likely to feel discomfort, and the operability is improved as compared with the prior art.

  According to the fifth aspect of the invention, in addition to the effect of any one of the second to fourth aspects, the trunnion arm 95 of the case 72 that houses the hydraulic pump side cylinder 47 and the hydraulic motor side cylinder 47 is provided. The first magnetic body 125 is detachably provided in the through-hole 72a formed at the position near the port block 71 on the side provided with the first magnetic body. Therefore, if the first magnetic body 125 is removed, the contaminants can be easily removed, and the operability of the hydrostatic continuously variable transmission H is improved more than before.

  Further, since the trunnion arm 95 is provided with the second magnetic body 126, a force attracting the first magnetic body 125 and the second magnetic body 126 can be generated, so that the hydrostatic continuously variable transmission H can be neutralized. When the operation is performed, the torque due to the return resistance is overcome and the neutral position is rotated, the output is surely stopped, and the traveling is surely stopped.

It is a side view of the seedling transplanting machine of one Example of this invention. It is a top view of the seedling transplanting machine of FIG. The structure of the hydraulic circuit of the hydraulic continuously variable transmission of the seedling transplanter of FIG. 1 is shown. The front view of the port disk of the hydraulic continuously variable transmission of FIG. 3 is shown. FIG. 4 is a side sectional view of the entire hydraulic continuously variable transmission of FIG. 3. FIG. 4 is an overall plan sectional view of the hydraulic continuously variable transmission of FIG. 3. The front view of the valve plate with which it mounts between the cylinder block and port disk shown in FIG. 5 is shown. FIG. 8A is a front view when a movement groove is provided in the valve plate of FIG. 7, and FIG. 8B is a front view inside the round frame of FIG. 8A. FIG. 9A and FIG. 9B are front views of modified examples in the round frame of FIG. FIG. 10A shows an enlarged cross-sectional view of a part of the trunnion shaft, the crank arm and the swash plate of the hydraulic continuously variable transmission shown in FIG. 3, and FIG. 10B shows an AA of FIG. A line arrow figure is shown. FIG. 4 is a hydraulic circuit diagram of a hydraulic valve mechanism C of the hydraulic continuously variable transmission of FIG. 3. It is an arrow view of the trunnion shaft attachment part of the hydraulic continuously variable transmission seen from the arrow A direction of FIG. FIG. 13 is an arrow view of a trunnion shaft mounting portion (a state in which a port block is removed) of the hydraulic continuously variable transmission as viewed from the direction of arrow B in FIG. 12. 14A is a side view of the main part of the front cover portion of the seedling transplanter of FIG. 1, and FIG. 14B is a plan view of the main part of the front cover portion. FIG. 15 (a) is a side view of the main part near the control part of the seedling transplanter of FIG. 1, and FIG. 15 (b) is a control part showing a state in which the fertilizer is supplied from the fertilizer bag R to the fertilizer tank by folding the seat. It is a principal part side view of the vicinity. FIG. 16 (a) is a front view of a valve plate of a generally used hydrostatic continuously variable transmission, and FIG. 16 (b) is an enlarged view in a round frame of FIG. 16 (a).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 and FIG. 2 are a side view and a plan view of a riding type rice transplanter equipped with a fertilizer application device as a granular material feeding device which is a typical example of the seedling transplanter of the present invention. In this riding type rice transplanter 1 with a fertilizer application, a seedling planting portion 4 is mounted on the rear side of the traveling vehicle body 2 via an elevating link device 3 so that the seedling planting portion 4 can be moved up and down. Is provided. The boarding operator refers to the left and right directions in the forward direction of the riding type rice transplanter as left and right, respectively, and the forward direction and the reverse direction are referred to as forward and backward, respectively.

  The traveling vehicle body 2 is a four-wheel drive vehicle including a pair of left and right front wheels 10 and 10 and a pair of left and right rear wheels 11 and 11 as drive wheels, and a mission case 12 is disposed at the front of the fuselage. Front wheel final cases 13, 13 are provided on the left and right sides of the case 12, and the left and right front wheels are mounted on the left and right front wheel axles projecting outward from respective front wheel support portions capable of changing the steering direction of the left and right front wheel final cases 13, 13. 10 and 10 are respectively attached. Further, the front end portion of the main frame 15 is fixed to the rear portion of the transmission case 12, and the rear wheel gear case 18 is supported by a rear wheel rolling shaft provided horizontally at the front and rear of the rear end of the main frame 15 in the horizontal direction. The rear wheels 11 and 11 are attached to a rear wheel axle that is supported in a freely rolling manner and projects outwardly from the rear wheel gear cases 18 and 18.

  The engine 20 is mounted on the main frame 15, and the rotational power of the engine 20 is transmitted to the transmission case 12 via a belt transmission device 21 and a hydraulic continuously variable transmission (HST) 23. The rotational power transmitted to the mission case 12 is shifted by a transmission in the case 12 and then separated into traveling power and external power to be extracted. A part of the traveling power is transmitted to the front wheel final cases 13 and 13 to drive the front wheels 10 and 10, and the rest is transmitted to the rear wheel gear cases 18 and 18 to drive the rear wheels 11 and 11. Further, the external take-out power is transmitted to a planting clutch case 25 provided at the rear part of the traveling vehicle body 2, and then transmitted to the seedling planting unit 4 by the planting transmission shaft 26, and also the fertilizer application device 5 by the fertilization transmission mechanism 28. Is transmitted to.

  The upper part of the engine 20 is covered with an engine cover 30, and a seat 31 is installed thereon. A front cover 32 incorporating various operation mechanisms is provided in front of the seat 31, and a handle 34 for steering the front wheels 10 and 10 is provided above the front cover 32. The engine cover 30 and the front cover 32 have horizontal floor steps 35 on the left and right sides of the lower end. The floor step 35 is partly grid-shaped (see FIG. 2), and mud on the shoe of the worker walking through the step 35 falls on the field. The rear part on the floor step 35 is a rear step 36 that also serves as a rear wheel fender.

  The elevating link device 3 is a parallel link mechanism and includes a single upper link 40 and a pair of left and right lower links 41 and 41. These links 40, 41, 41 are pivotally attached to a rear-view portal-shaped link base frame 42 erected on the rear end of the main frame 15, and a vertical link 43 is connected to the front end side thereof. ing. And the connecting shaft 44 rotatably supported by the seedling planting part 4 is inserted and connected to the lower end part of the vertical link 43, and the seedling planting part 4 is connected so as to be able to roll around the connecting shaft 44.

  An elevating hydraulic cylinder 46 is provided between a support member (not shown) fixed to the main frame 15 and the tip of a swing arm (not shown) formed integrally with the upper link 40. By expanding and contracting with hydraulic pressure, the upper link 40 is rotated up and down, and the seedling planting portion 4 is lifted and lowered with a substantially constant posture.

  The seedling planting section 4 has a six-row planting structure, a transmission case 50 that also serves as a frame, a mat seedling, and a left and right reciprocating motion to feed the seedlings one by one to the seedling outlet 51a of each row, and in a horizontal row When all the seedlings are supplied to the seedling outlet 51a, ..., seedling feeding belt 51b, ... seedling mounting base 51 for transferring the seedling downward, seedling planting for planting the seedling supplied to the seedling outlet 51a, ... in the field A device 52,... Includes a pair of left and right drawing markers 64 (FIG. 1) for drawing the aircraft path in the next stroke to the topsoil surface.

  In the lower part of the seedling planting part 4, a center float 55 is provided in the center, and side floats 56, 56 are provided on the left and right sides thereof. When the aircraft is advanced with these floats 55, 56, 56 in contact with the mud surface of the field, the floats 55, 56, 56 slide while leveling the mud surface, and the seedling planting device 52, ... to plant seedlings. Each of the floats 55, 56, and 56 is rotatably attached so that the front end side thereof moves up and down according to the unevenness of the soil surface of the field, and the vertical movement of the front part of the center float 55 is an angle-of-attack control sensor during planting work. The planting depth of the seedling is detected by switching a hydraulic valve (not shown) that controls the lifting hydraulic cylinder 46 according to the detection result and raising and lowering the seedling planting unit 4 according to the detection result. Is always kept constant.

  The fertilizer applicator 5 feeds the granular fertilizer stored in the fertilizer hopper 60 by a certain amount by the feeding sections 61,... And applies the fertilizer to the left and right sides of the floats 55, 56, 56 with the fertilizer hoses 62,. Guide to a guide (not shown), ..., and a grooved body 76 (Fig. 1) provided on the front side of the fertilizer guide, ..., and drop into a fertilizer structure formed near the side of the seedling planting strip ing. Air generated by the blower 58 driven by the blower electric motor 53 is blown into the fertilizer hose 62 through the air chamber 59 that is long in the left-right direction, and the fertilizer in the fertilizer hose 62 is forced by the wind pressure. It is designed to be transported.

The seedling planting unit 4 is provided with a rotor 27 (an example of a combination of the first rotor 27a and the second rotor 27b may be simply referred to as the rotor 27) as an example of a leveling device.
In addition, the seedling platform 51 has a frame structure 65 composed of a rectangular support frame 65b and a support roller 65a that supports the whole seedling planting portion 4 in the left-right direction and the up-down direction, and is formed in the left-right direction. It is the structure which slides to.

  In addition, on the left and right sides of the front portion of the traveling vehicle body 2, a pair of spare seedling platforms 38, 38 on which replenishment seedlings are placed can be pivoted to a position where they protrude from the front and back of the machine body and a position where they are aligned vertically. Is provided.

The first preliminary seedling stage 38a, the second preliminary seedling stage 38b, and the third preliminary seedling stage 38c on one side of the machine body are arranged in three upper and lower stages or arranged on the same plane.
The preliminary seedling platform 38 is supported by support machine frames 49a and 49b having a base side disposed below the floor step 35 of the traveling vehicle body 2 and is arranged in three upper and lower stages (stacked state) or three through the three moving link members 39. They are arranged on the same plane (deployed state).

  Further, a changeover switch 63 (which may be a button or a lever) (FIGS. 1 and 2) is used as a switching operation means for switching the preliminary seedling platforms 38a, 38b, and 38c between the unfolded state and the loaded state by the switching drive device 70. 31 is provided in the vicinity.

  The configuration of the hydraulic circuit of the hydraulic continuously variable transmission HST of this embodiment is shown in FIG. 3, the front view of the port disk is shown in FIG. 4, the side sectional view of the hydraulic continuously variable transmission HST is shown in FIG. A plan sectional view of the step transmission (HST) is shown in FIG. 7 shows a front view of the valve plate mounted between the cylinder block and the port disk. FIG. 10 (a) shows a part of the trunnion shaft, crank arm and swash plate of the hydraulic continuously variable transmission shown in FIG. An enlarged cross-sectional view is shown, and FIG. 10B shows a view taken along the line AA in FIG. FIG. 8 (a) is a front view when a movement groove is provided in the valve plate of FIG. 7, and FIGS. 8 (b), 9 (a), and 9 (b) are those of FIG. 8 (a). It is a front view at the time of changing the number of notches in each round frame.

  When the hydraulic circuit 66 and the hydraulic circuit 67 shown in FIG. 3 form a closed circuit and the swash plate 69 on the variable displacement hydraulic pump A side shown in FIG. The hydraulic pressure acting on the fixed displacement hydraulic motor B side becomes a high pressure. At this time, the hydraulic circuit 67 on the opposite side of the hydraulic circuit 66 has a low pressure so that the oil discharged from the fixed displacement hydraulic motor B side is a variable displacement hydraulic pump. Inhaled to A. FIG. 4 shows a front view of the valve plate (port disk) 86.

  The HST case 72 and the boost pump 73 (see FIG. 3) in which the variable displacement hydraulic pump A and the fixed displacement hydraulic motor B are housed are superposed on the port block 71 shown in FIGS. The input shaft 74 and the output shaft 75 whose axial directions are parallel to each other are supported. A hydraulic pump A and a trochoid rotor (not shown) of a boost pump 73 (see FIG. 3) are provided around the input shaft 74, and a hydraulic motor B is provided around the output shaft 75.

  In these hydraulic pump A and hydraulic motor B, a large number of cylinders 47 are arranged around the input shaft 74 and the output shaft 75 in parallel with the axial direction to constitute a cylinder block, and each cylinder 47 is slid in the axial direction. A moving piston 48 is provided. Each of the pistons 48 is supported at its tip by a ball joint of a joint disk 77 so as to be swingable, and is provided so as to be rotatable about shafts 74 and 75 with respect to a thrust plate 78 of a swash plate 69.

  The cylinder block rotates integrally with the input shaft 74, the output shaft 75, and the like, but the joint disk 77 that rotates together with the piston 48, the thrust plate 78 that is slidably guided, and the swash plate 69 that is integrated therewith are provided in the HST case. The angle of inclination of the swash plate 69 on the hydraulic motor B side is constant, and the angle of the swash plate 69 on the hydraulic pump A side is controlled by a control lever or the like. By operating and controlling, the stroke amount of the reciprocating movement of the piston 48 on the hydraulic pump A side is changed, so that the hydraulic motor B on the counterpart side passes through the hydraulic circuit 66 on the forward side and the hydraulic circuit 67 on the reverse side. The speed is changed by changing the rotational speed of the piston 48 under a constant stroke amount. A part of the forward hydraulic circuit 66 and the reverse hydraulic circuit 67 are provided inside the port block 71.

  Therefore, when the swash plate 69 is at a right angle to the input shaft 74, the pistons 48 do not reciprocate in the axial direction even if the cylinder 47 on the input shaft 74 side is rotated. There is no transmission to and is in a neutral state. Further, when the swash plate 69 on the hydraulic pump A side increases the inclination angle to the forward rotation side, the stroke of the piston 48 also increases, and the hydraulic pressure acting on the hydraulic motor B side through the hydraulic circuit 66 also becomes high. At this time, the hydraulic circuit 67 on the opposite side of the hydraulic circuit 66 becomes a low pressure, and the oil discharged from the hydraulic motor B side is sucked into the pump A side. Accordingly, the output shaft 75 by the motor B is sequentially increased from the neutral state to the forward rotation side high speed state.

  Conversely, when the angle of the swash plate 69 on the hydraulic pump A side is increased from the neutral state to the reverse side, the hydraulic circuit 67 becomes high pressure and oil flows to the hydraulic motor B side, and the hydraulic circuit 66 becomes low pressure. As a result, the output shaft 75 is continuously variable in the reverse direction. The boost pump 73 replenishes oil into the hydraulic circuits 66 and 67 from the tank port T, and passes through an oil filter 80, a main relief valve 81, field valves (check valves) 82a and 82b, a neutral valve 83, and the like. It communicates with the hydraulic circuits 66 and 67. A high pressure relief valve 85 is provided between the hydraulic circuits 66 and 67.

  As described above, the block of the cylinder 47 of the pump A and the motor B rotates together with the input shaft 74 and the output shaft 75, but the cylinder port of each cylinder 47 is located on the end face of the block of each cylinder 47 on the port block 71 side. 90 and 91 (see FIG. 4) are arranged at equal angular intervals, and rotate and slide on a valve plate (port disk) 86 attached to the port block 71. The valve plate 86 is formed with a shaft hole 87 through which the input shaft 74 and the output shaft 75 are inserted at the center thereof, and the outer periphery of the shaft hole 87 along the rotation surfaces of the cylinder ports 90 and 91. Arc-shaped elongated holes 88 and 89 are formed over a predetermined rotation angle.

  The cylinder ports 90 and 91 communicate with the port block 71 formed with the hydraulic circuits 66 and 67 via the ports 88 and 89, but the operation angle of the swash plate 69 is at the forward rotation side shift position. If the side port 88 is a high pressure on the hydraulic discharge side, the other port 89 is a low pressure on the hydraulic suction side. Further, when the operation angle of the swash plate 69 exceeds the neutral position and is in the reverse shift position, the discharge side and the suction side are reversed.

  A relief port (not shown) is provided at the center of the pressure transition section (b) at the bottom dead center of the valve plate (port disk) 86, and a relief valve (not shown) that communicates with the relief port is attached to the port block 71. Accordingly, when each cylinder port 90, 91 of the cylinder block of the hydraulic pump A or the hydraulic motor B moves from the port 88 on the high pressure region side to the port 89 on the low pressure region side through the pressure transition section (b), the cylinder port 90 is switched from the communication state with the port 88 to the relief port in the pressure transition section (B), and the oil pressure is absorbed by the relief valve. Therefore, when the oil pressure at this time is too high, the oil pressure is relaxed and absorbed by the relief valve, and the oil pressure is smoothly lowered in the subsequent switching to the port 89 in the low pressure region.

  Such a relief port and a relief valve may be provided in the port block 71 straddling both the hydraulic pump A and the hydraulic motor B, or may be provided in any one valve plate (port disk) 86.

  The adjusting screw 94 is screwed into the case 72 in the direction of the input shaft 74 and moves and adjusts the swash plate 69 along the direction of the input shaft 74, thereby changing and adjusting the distance from the cylinder 47. At this time, a trunnion shaft 95 orthogonal to the input shaft 74 is provided, and a pin slider 98 of a crank arm 96 integral with the trunnion shaft 95 is provided at the tip of the trunnion shaft 95 in a roller groove 69a formed in the swash plate 69. By engaging and rotating the trunnion shaft 95, the pin slider 98 is swung, and the inclination angle of the swash plate 69 is operated.

  As shown in FIG. 3, the working vehicle of this embodiment is configured such that the amount of hydraulic oil discharged by the reciprocating motion of a plurality of pistons 48 arranged in parallel with the input shaft 74 that inputs power from the engine 20 and the discharge direction. The hydraulic closed circuit 66 includes a variable displacement hydraulic pump A that adjusts the pressure and a fixed displacement hydraulic motor B that changes the rotational speed and direction of the output shaft 75 in accordance with the amount of oil discharged from the hydraulic pump A and the direction of oil discharge. , 67 are connected to each other through a hydrostatic continuously variable transmission H.

  Further, as shown in FIGS. 5 and 6, a part of the hydraulic closed circuits 66 and 67 is provided inside, and a port block 71 is arranged in a direction orthogonal to the input shaft 74 and the output shaft 75. The port block 71 and the hydraulic pump The hydraulic closed circuits 66 and 67 are formed by connecting the inside of the block of the hydraulic pump side cylinder 47 with A and the inside of the block of the hydraulic motor side cylinder 47 with the hydraulic motor B, respectively.

  Further, FIG. 4 and FIG. 7 show the front view, FIG. 5 and FIG. 6 between the port block 71 and the block of the cylinder 47 on the hydraulic pump A side and between the port block 71 and the block of the cylinder 47 on the hydraulic motor B side. A thin plate-like valve plate 86 having spaces 88 and 89 for forming a hydraulic closed circuit, which is slightly shown, is provided.

  In this embodiment, the valve plate 86 has at least two moving grooves (notches) 84 for ejecting hydraulic oil flowing through the hydraulic closed circuits 66 and 67 from the cylinder 47 on the hydraulic pump A side toward the spaces 88 and 89. The provision is shown in FIG. 8 and FIG. FIG. 8A is a front view when a notch is provided in the valve plate of FIG. 7, and FIGS. 8B, 9A, and 9B are inside the round frame of FIG. 8A. It is a front view at the time of changing the number of notches respectively. As shown in FIG. 8A, for example, six arc-shaped space portions (long holes) 88 and 89 are provided around the center O of the valve plate 86 on the same circumference.

  As shown in FIG. 8 (b), from the notches 84 arranged in parallel to the valve plate 86 so that the hydraulic oil is ejected stepwise in accordance with the increase / decrease operation of the traveling speed, into the spaces 88 and 89. When the hydraulic oil is ejected and the ejection angle of each notch 84 is set to an angle at which the hydraulic oil ejected in the spaces 88 and 89 collide with each other, the hydraulic oil collides with each other to weaken the momentum of the jet, The durability of the hydrostatic continuously variable transmission H can be improved more than before without generating cavitation that may occur when the hydraulic oil collides with the wall surfaces of the space portions 88 and 89.

  Further, since the jet of hydraulic oil does not directly hit the wall surface of the valve plate 86 that forms the space portions 88 and 89, the shape of the space portions 88 and 89 can be prevented from changing, and the amount of hydraulic oil ejected can be changed. Without this, the output of the hydrostatic continuously variable transmission H is stabilized.

  As shown in FIGS. 8B and 9B, an even number of notches 84 are provided in the valve plate 86, and a pair of diagonal lines passing through the center O of a circle formed by a plurality of annularly disposed spaces 88 and 89 are provided. Two or four notches 84 are provided adjacent to each other in the spaces 88 and 89, and before hydraulic oil ejected from the even number of notches 84 reaches the wall surface forming the spaces 88 and 89 of the valve plate 86. The jetting angle that merges inside the space portions 88 and 89.

  Even-numbered notches 84 are arranged on a diagonal line passing through the center O of the circle formed by the plurality of space portions 88 and 89, and the hydraulic oil ejected from the notches 84 reaches the wall surfaces forming the space portions 88 and 89 of the valve plate 86. By setting the jetting angle of the hydraulic oil so that it merges in the space portions 88 and 89 before the operation, the hydraulic oil jetted from the notch 84 collides with each other in the space portions 88 and 89 to weaken the momentum of the jet flow. Therefore, the cavitation that may occur due to the hydraulic oil colliding with the wall surface forming the space portions 88 and 89 formed in the valve plate 86 does not occur, and the durability of the hydrostatic continuously variable transmission H is conventional. Improve over technology.

  Further, by forming a plurality of notches 84, it is possible to secure a volume of space necessary for the passage of hydraulic oil, so that noise and vibration are prevented from occurring when the output of the hydrostatic continuously variable transmission H is changed, The operator is less likely to feel discomfort, and the operability is improved as compared with the prior art.

  The space portions 88 and 89 of the valve plate 86 are annularly arranged, and as shown in FIG. 9A, three or more odd notches 84 reaching the space portions 88 and 89 are provided, and a plurality of space portions 88 and 89 are provided. The odd-numbered notches 84 are provided adjacent to a pair of diagonal spaces 88 and 89 passing through the center O of the circle formed by the odd-numbered notches 84, and hydraulic oil ejected from the odd-numbered notches 84 is provided in the space portions 88 and 89. A configuration may be adopted in which the jet angle is formed inside each space portion 88 and 89 before reaching the valve plate wall surface forming the.

  In this case, the odd number of notches 84 are provided adjacent to a pair of diagonal spaces 88 and 89 passing through the center O of a circle formed by a plurality of spaces 88 and 89 arranged in a ring on the valve plate 86. Since the hydraulic oil ejected from the odd number of notches 84 joins the space portions 88 and 89 before reaching the wall surface of the valve plate 86 forming the space portions 88 and 89, the hydraulic oil The momentum of the jet can be reduced, and cavitation does not occur when the hydraulic oil ejected from the odd number of notches 84 hits the ends of the spaces 88 and 89, and the hydrostatic continuously variable transmission H The durability is improved compared to the prior art.

  In addition to the configuration in which the other notches 84 are formed on the basis of the notch 84 at the center as described above, the hydraulic oil that ejects the angle of each notch 84 without using the specific notch 84 as a reference is the space portion 88, It is good also as a structure made into the angle which merges 89 inside.

  Since the notch 84 has an odd number, the entire volume of the notch 84 can be secured, so that noise and vibration are prevented when the output of the hydrostatic continuously variable transmission H is changed, and the operator feels uncomfortable. It is difficult and the operability is improved over the prior art.

FIG. 10A shows an enlarged sectional view of a part of the trunnion shaft 95, the crank arm 96 and the swash plate 69 shown in FIG. 6, and FIG. 10B shows an AA line arrow in FIG. A view is shown.
An eccentric cam 100 is interposed between a crank arm 96 for operating the swash plate 69 and a pin slider 98. In the eccentric cam 100, a pin 100a and a pin 100b are rotatably inserted into a crank arm 96 and a pin slider 98, respectively, and the two pins 100a and 100b are provided at positions eccentric from each other.

  Accordingly, when the crank arm 96 is operated according to the rotational position of the trunnion shaft 95, the operation amount is transmitted to the pin slider 98 via the eccentric cam 100, and the pin slider 98 is moved to the groove of the swash plate 69. Slide 62a by a predetermined amount. The inclination angle of the swash plate 69 is determined according to a predetermined amount of sliding of the pin slider 98.

  As shown in FIG. 12 (an arrow view as viewed from the direction of arrow A in FIG. 6) and FIG. 13 (a partially transparent arrow view as viewed from the direction of arrow B in FIG. 12 with the port block 71 removed), A through hole 72a is provided through the hydrostatic continuously variable transmission (HST) case 72 on the side where the arm 95 is provided and close to the port block 71, and a first magnetic body (permanent magnet) is provided in the through hole 72a. ) 125 may be detachably attached, and a configuration in which the second magnetic body 126 is attached to the trunnion arm 95 may be employed.

  By adopting this configuration, the first magnetic body 125 is detachably provided in the through hole 72a formed in the HST case 72 on the side where the trunnion arm 95 is provided and near the port block 71. Since the metallic contaminants mixed in the hydraulic oil can be adsorbed by the first magnetic body 125, the contaminants can be easily removed by removing the first magnetic body 125, and the hydrostatic continuously variable transmission is achieved. The operability of the device is improved more than before.

  By providing the second magnetic body 126 on the trunnion arm 95, it is possible to generate a pulling force between the first magnetic body 125 and the second magnetic body 126, so that the hydrostatic continuously variable transmission is operated neutrally. Sometimes, it overcomes the torque due to the return resistance and rotates to the neutral position, the output is reliably stopped, and the traveling is surely stopped.

  In addition, the working vehicle of the present invention includes a raising / lowering cylinder 46 for operating a raising / lowering link mechanism 3 for raising / lowering a seeding planting unit 4 and a seeding planting unit 4 in place of the seeding planting unit 4 and hydraulic oil in the lifting cylinder 46. Is provided with a hydraulic valve mechanism C.

  When raising and lowering the working device, particularly when lowering the working device, conventionally, the working valve lowering speed control is performed on the hydraulic valve mechanism C by using an adjustable needle valve. However, depending on the load of the working device, the descending speed of the working device varies, and adjustment thereof is difficult.

  Therefore, a hydraulic circuit for the hydraulic valve mechanism C as shown in FIG. 11 is provided. The hydraulic circuit of FIG. 11 is characterized by the provision of a pressure reducing valve 105 that keeps the load pressure constant when the elevating link mechanism 3 is lowered and an orifice 106 that regulates the flow rate of hydraulic oil to be constant.

  A hydraulic valve mechanism C that supplies hydraulic oil from the hydraulic pump P of the hydraulic circuit shown in FIG. 11 to the lifting cylinder 46 includes a branch valve 109, a branch valve switching valve 110, a lifting switching valve 112 of the lifting cylinder 46, and a check valve 113 in order. The hydraulic oil is sent to the elevating cylinder 46 via.

  In the hydraulic circuit shown in FIG. 11, the orifice 106 is disposed in the oil passage of the hydraulic oil when the elevating cylinder 46 is lowered in the elevating switching valve 112, and the hydraulic oil when the elevating cylinder 46 is lowered is normal oil in the pressure reducing valve 105. A configuration in which oil can be returned directly from the pressure reducing valve 105 to the oil tank T without going through the flow path but through the flow dividing valve 109, the flow dividing valve switching valve 110, the lift switching valve 112 of the lifting cylinder 46, and the check valve 113. Also equipped.

  In this way, the load pressure of the hydraulic valve mechanism C when the elevating cylinder 46 is lowered is controlled to be constant by the pressure reducing valve 105, and the flow rate of the working oil is controlled to be constant by the orifice 106, so that the work is performed when the elevating link mechanism 3 is lowered. It is possible to prevent the descending speed from increasing due to the weight of the device. This prevents the working device from descending earlier than the operator's intention and colliding with the ground or disturbing the working height.

  A relief valve 115 is provided in the oil passage at the outlet of the hydraulic pump P, and the oil passage just before the lifting cylinder 46 is closed when the lifting cylinder 46 is extended, that is, when the seedling planting portion 4 is lowered. Since the check valve 114 is arranged in parallel with the pressure reducing valve 105, the hydraulic oil freely passes through the check valve 114 when the lifting cylinder 46 is contracted, that is, when the seedling planting part 4 is raised. The flow rate of the hydraulic oil is fast, and the seedling planting part 4 is quickly raised.

  As a result, the hydraulic pressure becomes unstable when the seedling planting unit 4 is raised, and the timing at which the seedling planting unit 4 is separated from the field scene is prevented from being delayed, and the lower part of the seedling planting unit 4 is damaged, It is prevented that the farming scene is disturbed during turning and the planting depth of the seedling is affected.

  The pressure reducing valve 105 and the check valve 114 are disposed between the check valve 113 and the cylinder 46. Thus, since the pressure held by the check valve 113 becomes constant, it is easy to set a pilot pressure that pushes the check valve 113 down when the work implement is lowered.

  14 (a) is a side view of the main part of the front cover part, and FIG. 14 (b) is a plan view of the main part of the front cover part. In the fuel tank 117 extending from the inside of the front cover 32 to the floor step 35, A fuel supply port 117a of the fuel tank 117 is provided on the upper left of the upper surface.

  A hose 118 is extended from the solid line position in FIG. 14A to the solid line position in FIG. 14B to the left rear corner of the partition plate 119, and a cap 121 is provided on the hose 118. A partition plate portion surrounding the periphery of the hose 118 and the cap 121 is separated and fixed to the hose 118. Furthermore, a handle 122b is provided on the rear inner side of the separate partition plate 122, a vertical rotation shaft 122a is provided in front of the separate partition plate 122, and a hose 118, a cap 121, and another are provided around the rotation shaft 122a. The body partition plate 122 is rotated horizontally at the connecting portion with the fuel tank 117.

  Thus, until now, when the fuel filler port 117a of the fuel tank 117 was in the front cover 32, it had to be submerged under the front cover 32, but the above configuration solved the disadvantage and fueled the fuel. The opening 117a can be pulled out to a position where the opening 117a is opened upward, facilitating the refueling operation, and the refueling port 117a can be housed in the front cover 32 at normal times, so that it does not interfere with the operation.

  FIG. 15A is a side view of the main part in the vicinity of the control part, and FIG. 15B is a side view of the main part in the vicinity of the control part showing the state in which the seat 31 is bent and the fertilizer is supplied from the fertilizer bag R to the fertilizer tank 60. FIG.

  The seat 31 has two folding fulcrums 31a and 31b as shown in FIG. 15 (a), and when the fertilizer is supplied to the fertilizer tank 60 from the fertilizer bag R, the handle 34 faces downward as shown in FIG. 15 (b). After tilting, the fertilizer bag R is placed on the seat 31 by being tilted forward so that a part of the seat 31 overlaps with the tilt. At this time, the bending fulcrums 31a and 31b of the seat 31 are locked. Then, by rotating the seat 31 on which the fertilizer bag R is placed 180 degrees around the support portion 31c and moving the fertilizer bag R above the fertilizer tank 60, the fertilizer is easily moved from the fertilizer bag R into the fertilizer tank 60. Can be made.

  The present invention is not limited to a riding seedling transplanter equipped with a seedling planting unit, and can also be used for other work vehicles.

DESCRIPTION OF SYMBOLS 1 Riding type rice transplanter with fertilizer 2 Traveling vehicle body 3 Elevating link device 4 Seedling planting part 5 Granule feeding device (fertilizer) 10 Front wheel 11 Rear wheel 12 Mission case 13 Front wheel final case 15 Main frame 18 Rear wheel gear case 20 Engine 21 Belt transmission 23 Hydraulic continuously variable transmission (HST)
25 Planting clutch case 26 Planting transmission shaft 27 (27a, 27b) Rotor 28 Fertilizer transmission mechanism 30 Engine cover 31 Seat 32 Front cover 33 Control section 34 Handle 35 Floor step 36 Rear steps 38a, 38b, 38c First to third Preliminary seedling stage 39 Moving link member 40 Upper link 41 Lower link 42 Link base frame 43 Vertical link 44 Connecting shaft 46 Lifting hydraulic cylinder 47 Cylinder 48 Piston 49a, 49b Supporting machine frame 50 Transmission case 51 Seedling stage 51a Seedling outlet 51b Seedling feeding belt 52 Seedling planting device 53 Blower electric motor 55 Center float 56 Side float 58 Blower 59 Air chamber 60 Fertilizer hopper 61 Feeding portion 62 Fertilization hose 62a Roller groove 63 Changeover switch 64 Drawing marker 65 Frame Structure 65a supporting rollers 65b support frame 66 forward-side hydraulic circuit 67 reverse-side hydraulic circuit 69 the swash plate
70 Switching drive device 71 Port block 72 HST case 72a Through hole
73 Boost Pump 74 Input Shaft 75 Output Shaft 76 Groove Groove 77 Joint Disc 78 Thrust Plate 79 Ball Seat 80 Oil Filter
81 Main relief valve 82a, 82b Field valve 83 Neutral valve 84 Moving groove (notch)
85 High pressure relief valve 86 Port disk 87 Shaft hole 88, 89 Arc-shaped oblong port 90, 91 Cylinder port 94 Adjustment screw 95 Trunnion shaft 96 Crank arm 98 Pin slider 100 Eccentric cam 100a, 100b Pin 105 Pressure reducing valve 106 Orifice 109 Split valve 110 Split valve switching valve 112 Lift switching valve 113 Check valve 114 Check valve 115 Relief valve 117 Fuel tank 118 Hose 119 Partition plate 121 Cap 122 Separate partition plate 125 First magnetic body 126 Second magnetic body A Variable capacity type Hydraulic pump B Fixed displacement hydraulic motor C Hydraulic valve mechanism H Hydrostatic continuously variable transmission R Fertilizer bag T Oil tank

Claims (5)

Piston cylinders (not shown) that have pistons (48) that operate by receiving a driving force from a driving source (20) of the traveling vehicle body (2) around an input shaft (74) and an output shaft (75) of the driving force. 47)
A valve plate (86) having a plurality of space portions (88, 89) through which hydraulic oil from and out of the piston cylinder (47) is formed is provided in a direction perpendicular to the input shaft (74) and the output shaft (75);
In the valve plate (86), in order to cause the hydraulic oil to be ejected stepwise to the space (88, 89) in accordance with the increase / decrease operation speed when the output from the piston cylinder (47) is changed, At least two moving grooves (28), each of which is set so that the jetted hydraulic oils intersect at the spaces (88, 89) and collide with each other in the spaces (88, 89). A work vehicle comprising the hydrostatic continuously variable transmission (H) provided. The amount and direction of hydraulic oil discharged by reciprocating motion of a plurality of pistons (48) arranged in parallel in conjunction with an input shaft (74) for inputting power from the drive source (20) of the traveling vehicle body (2). The hydraulic pump (A) to be adjusted and the hydraulic motor (B) that changes the rotational speed and direction of the output shaft (75) according to the amount of oil discharged from the hydraulic pump (A) and the direction of oil discharge are closed by a hydraulic circuit ( 66, 67) in a work vehicle equipped with a hydrostatic continuously variable transmission (H) connected via
A part of the hydraulic closed circuit (66, 67) inside, a port block (71) provided in a direction orthogonal to the input shaft (74) and the output shaft (75);
The inside of the block of the piston cylinder (47) on the side of the hydraulic pump that houses the hydraulic pump (A), the inside of the block of the piston cylinder (47) on the side of the hydraulic motor that houses the hydraulic motor (B), and the port block (71) Are connected to each other to form the hydraulic closed circuit (66, 67),
The space for forming the hydraulic closed circuit between the port block (71) and the block of the piston cylinder (47) on the hydraulic pump side and between the port block (71) and the block of the piston cylinder (47) on the hydraulic motor side. A valve plate (86) having (88, 89),
The hydraulic fluid flowing from the piston cylinder (47) on the hydraulic pump side and the piston cylinder (47) on the hydraulic motor side via the hydraulic closed circuit (66, 67) to the valve plate (86) is increased or decreased. A hydrostatic continuously variable transmission (H) characterized in that it has at least two moving grooves (84) that are ejected toward the space (88, 89) in accordance with the operation is provided. The work vehicle according to claim 1. The space portions (88, 89) of the valve plate (86) are annularly arranged,
An even number of moving grooves (84) reaching the space portions (88, 89) are provided,
The even number of moving grooves (84) are adjacent to a pair of space portions (88, 89) on a diagonal line passing through the center (O) of a circle formed by a plurality of space portions (88, 89) arranged in an annular shape. Provided,
The ejection angle at which the hydraulic oil ejected from the even number of moving grooves (84) joins inside the space (88, 89) before reaching the wall surface forming the space (88, 89) of the valve plate (86) The work vehicle according to claim 2, wherein The space portions (88, 89) of the valve plate (86) are annularly arranged,
An odd number of three or more moving grooves (84) reaching the space (88, 89) are provided,
The odd number of moving grooves (84) are provided adjacent to a pair of diagonal spaces (88, 89) passing through the center (O) of a circle formed by the plurality of spaces (88, 89),
Before the hydraulic oil ejected from the odd number of moving grooves (84) reaches the valve plate wall surface forming each space portion (88, 89), the ejection angle is set to merge inside each space portion (88, 89). The work vehicle according to claim 2. A trunnion arm (95) that switches the output of the hydrostatic continuously variable transmission (H) by rotating;
Passes through the case (72) that houses the piston cylinder (47) on the hydraulic pump side and the piston cylinder (47) on the hydraulic motor side on the side where the trunnion arm (95) is provided and close to the port block (71) A through hole (72a) is provided,
A first magnetic body (125) is detachably attached to the through hole (72a),
The work vehicle according to any one of claims 2 to 4, wherein a second magnetic body (126) is attached to the trunnion arm (95).

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