JP2002283860A - Maintenance vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a good use of a case block of a hydraulic continuously variable transmission when connecting a front vehicle body and a rear vehicle body, to facilitate a building work including the connection between the front and the rear vehicle bodies with a certain level of strength and accuracy, and to prevent deteriorating of a hydraulic oil by improving the cooling of the lubricant. SOLUTION: This invention steps up a large cube unit 12 on a case block 10 of the hydraulic continuously variable transmission used as a construction material of a vehicle connecting the front vehicle body and the rear vehicle body, forms a storage space S1 for a main clutch 9 on the large cube unit 12, is equipped with a walling unit for supporting shafts 13 which supports a transmission shafts on the side of clutch 17 and a rotating shaft on the side of pump inside the case block 10, forms a space for mounting gear S2 inside the walling unit for supporting shafts 13, and interconnects the space for mounting gear S2 with a transmission chamber space S4 where exists a pump P and a motor M of the hydraulic continuously variable transmission device 10 at a transmission block unit 11 to be able to circulate hydraulic oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main clutch and a hydrostatic continuously variable transmission for connecting and disconnecting engine power between a front body equipped with an engine and a rear body equipped with a gear type transmission. The present invention relates to a work vehicle such as an agricultural work vehicle or a light civil engineering work vehicle in which a case block of the hydrostatic continuously variable transmission is used as a vehicle body component for connecting a front vehicle body side and a rear vehicle body side.

[0002]

2. Description of the Related Art As described above, a frameless type working vehicle, for example, a frameless type, which uses a case block of a hydrostatic continuously variable transmission as a vehicle body connecting member between a front vehicle body and a rear vehicle body. The tractor has a reduced number of parts and assembly compared to a frame-type tractor in which the engine and hydrostatic continuously variable transmission are mounted on the front and rear body frames that extend between the front and rear body sides. Work vehicles that can reduce man-hours and have different advantages from tractors of the type equipped with a body frame have attracted attention.
The body structure of a conventional frameless tractor is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-91380.
A clutch housing containing a main clutch for intermitting engine power between a front body side equipped with an engine and a rear body body equipped with a gear type transmission, and a case block constituting a hydrostatic continuously variable transmission; Were connected in series. Further, the space for disposing the transmission gear for transmitting the transmission shaft from the main clutch and the rotating shaft of the hydrostatic continuously variable transmission is different from the space on the main clutch side and the space on the hydrostatic continuously variable transmission side. Is constituted by an independent space, and the supply of lubricating oil to the transmission gear
The piping was connected so that return oil from the hydrostatic continuously variable transmission was supplied.

[0003]

In the above-described conventional structure, when connecting the case block constituting the hydrostatic continuously variable transmission to the front and rear vehicle bodies, there are many connection points.
The connection area is small, and there are disadvantages in terms of strength and processing disadvantages in which it is difficult to obtain assembly accuracy. In addition, the supply of lubricating oil to the transmission gear provided in the space for disposing the transmission gear for transmitting the transmission shaft from the main clutch and the rotating shaft of the hydrostatic continuously variable transmission is performed by the hydrostatic continuously variable transmission. A complicated piping structure is required to use the return oil from the device, which not only has disadvantages in terms of manufacturing and processing, but also lubricates the transmission gear that rotates at high speed in a relatively narrow gear installation space. The operating oil is relatively easily heated, and the operating oil deteriorates quickly. An object of the present invention is to effectively use a case block constituting a hydrostatic continuously variable transmission as an intermediate vehicle body that connects a front vehicle body and a rear vehicle body,
The assembly work involving the connection of the front and rear vehicle bodies is required to ensure the required strength and accuracy, and to facilitate the connection work, and to make it possible to cool the lubricating oil satisfactorily, thereby suppressing the deterioration of the hydraulic oil. It is to make.

[0004]

The technical means of the working vehicle of the present invention taken to achieve the above object is as follows. [Invention according to claim 1] In the invention according to claim 1,
A main clutch for interrupting engine power and a hydrostatic continuously variable transmission are interposed between a front body equipped with an engine and a rear body equipped with a gear type transmission, and the hydrostatic continuously variable transmission is provided. In a work vehicle using a case block of the device as a vehicle body component for connecting a front vehicle body and a rear vehicle body, the case block of the hydrostatic continuously variable transmission is
A large-diameter bowl-shaped part is integrally formed in a state where the upper edge is higher than the upper surface of a transmission block part constituting a case wall of a pump and a motor of the hydrostatic continuously variable transmission, and the large-diameter bowl-shaped part is formed. A housing space for the main clutch is formed, and inside this case block, a shaft support for supporting a clutch-side transmission shaft extending from the main clutch side and a pump-side rotary shaft extending from the pump side. A wall is provided, and a transmission gear provided at a shaft end of the clutch-side transmission shaft and a transmission gear provided at a shaft end of the pump-side rotation shaft are meshed with each other in the shaft support wall. A space for disposing gears is formed, and the space for disposing the gears and the space in the transmission block where the pump and motor of the hydrostatic continuously variable transmission are located in the transmission block portion are used for the flow of hydraulic oil. Communicated as possible.

[0005] In the vehicle body structure of the working vehicle configured as described above, the case block of the hydrostatic stepless transmission is formed by the case of the transmission block portion forming the case wall of the pump and the motor of the hydrostatic stepless transmission. Since the large-diameter bowl-shaped portion is integrally formed so that the upper edge is higher than the upper surface, the connection area with the front vehicle body is increased, and improvement in connection strength can be expected. In addition, since the case block is formed by integrating a large-diameter bowl-shaped portion having a storage space for the main clutch, the number of connection points at which connection points with the clutch housing are omitted is reduced by one. However, improvement in connection strength can be expected. Then, at the place where the case block is connected to the front vehicle body, not through the rotating shaft for input to the pump of the hydrostatic continuously variable transmission, but through the transmission shaft geared to the transmission gear of the rotating shaft. The main clutch will be engaged. In other words, the coupling with the main clutch fixed to the front vehicle body side different from the case block does not use the input shaft to the pump that requires assembly accuracy, but rather provides some accuracy through the gear transmission mechanism. Since the transmission shaft which can be provided is connected, there is also an advantage that required assembly accuracy can be reduced to some extent.

In addition, by adopting the above configuration, there is provided a portion in which the case cross-sectional shape changes from the upper surface of the speed change block portion to the large-diameter bowl-shaped portion. Although there is a possibility of becoming a weak point, in the present invention, a wall portion having a large dimension in the front-rear direction is formed so that a shaft supporting wall portion is formed inside the case and the shaft supporting wall portion forms an interior space of the transmission gear. Therefore, the strength weak point portion due to the change in the cross-sectional shape can be satisfactorily reinforced to improve the strength of the case block itself. Further, the gear disposition space formed in the shaft supporting wall portion is communicated with the transmission room space in which the pump and the motor of the hydrostatic continuously variable transmission in the transmission block portion are provided, and the hydraulic oil is provided. Distribution is possible. As a result, it is possible to omit the oil piping from the hydrostatic continuously variable transmission to the space for disposing the gears and the oil piping from the space for disposing the gears to the transmission space, and to lubricate without requiring a complicated piping structure. Not only the oil passage can be configured, but also the space for gears and the space for the gearbox are substantially integrated to expand the space volume, so the lubricating oil temperature rises only in the narrow space for gears. Is easy to avoid occurring rapidly.

In the invention according to the second aspect, the return oil of the hydraulic oil supplied from the pressure oil supply pump PO to the hydrostatic stepless transmission is not returned to the hydraulic oil tank. Then, the oil is supplied to the suction port of the pressure oil supply pump via an oil cooler.

[0008] By adopting the above configuration, the return oil cooled by the oil cooler is supplied to the suction port of the pressure oil supply pump, and is returned to the hydrostatic stepless transmission without passing through the hydraulic oil tank. It can lead to the supply channel. In other words, the supply path to the hydrostatic continuously variable transmission uses a high-performance filter to purify hydraulic oil and perform cooling processing with an oil cooler, so that a relatively clean state is maintained. In the hydraulic oil tank, the hydraulic oil that has returned through various hydraulic devices and gear lubrication parts is generally present in a somewhat dirty state. Here, if the return oil from the hydrostatic continuously variable transmission that is maintained in a clean state by the high-performance filter is mixed, the amount of processing in the high-performance filter and the oil cooler when recirculating will increase. Become. On the other hand, according to the second aspect of the present invention, as described above, the return oil of the hydraulic oil supplied to the hydrostatic continuously variable transmission is not returned to the hydraulic oil tank, but is returned to the hydraulic oil tank via the oil cooler. The oil is supplied to the suction port of the supply pump, and the cleanliness and cooling state of the return oil from the hydrostatic continuously variable transmission can be maintained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Overall Configuration of Work Vehicle] As shown in FIG. 1, a pair of left and right driveable front wheels 1, 1 and rear wheels 2, 2 are connected to a front body 3, a rear body 4, The front vehicle body 3 and the rear vehicle body 4 are
The agricultural tractor, which is an example of a frameless type work vehicle, is configured by being connected with the tractor. The front body 3
The engine E, a driving unit 3B equipped with a hood covering the engine on a front frame 3A integrated with the engine E, and a steering handle 3C for swinging and steering the front wheels 1 are integrally assembled. It is composed. The rear body 4 is provided with a traveling transmission case 6 for transmitting traveling power to each of the front wheels 1 and 1 and the rear wheels 2 and 2, a driving seat 4A is installed on an upper portion thereof, and various operations are performed on the rear side. The apparatus is provided with a lift arm 4B for connecting the device so as to be able to move up and down freely, and a power take-off shaft 4C for transmitting power to the connected various working devices. As shown in FIGS. 1 and 2, the traveling transmission case 6 includes a transmission case main body 6 a having a front end connected to a case block 10 constituting the intermediate vehicle body 5, and a front end connected to a rear end of the transmission case main body 6 a. The side is formed by a differential case portion 6b which is bolted. The intermediate vehicle body 5 is directly connected to the front vehicle body 3 and the rear vehicle body 4 to form a frameless vehicle together with the front vehicle body 3 and the rear vehicle body 4. A front end of the wheel housing 3D is bolt-connected to a rear portion thereof, and a case block 10 having a rear portion bolted to a front end of the traveling transmission case 6. This tractor is connected to a tillage device at the rear to form a riding tiller,
It constitutes various working vehicles.

[Transmission system] The pair of left and right front frames 3
A differential mechanism 7A for a front wheel is provided in an intermediate portion of a front wheel transmission case 7 supported by A and 3A, and a differential mechanism 7B for a rear wheel is provided in the differential case portion 6b.
By transmitting the rotational output of the engine E to the two differential mechanisms 7A and 7B by the transmission structure shown in FIG. 3 to drive the front and rear wheels 1 and 2, the vehicle body can run on its own.

That is, the rotational power of the flywheel 8 as an engine output member located inside the flywheel housing portion 3D is transmitted to the main clutch 9 to which the rotational power of the flywheel 8 is transmitted, and from the main clutch 9 The rotating power is transmitted to a gear transmission mechanism 18 composed of an input gear 18a and an output gear 18b by a transmission shaft 17 whose front end is connected by spline engagement, and the rotation of the output gear 18b of the gear transmission mechanism 18 is performed. The power is transmitted to the input rotary shaft 22 of the main traveling transmission 20 composed of a hydrostatic continuously variable transmission. The rotational power of the output rotary shaft 23 of the traveling main transmission 20 is transmitted to the traveling auxiliary transmission 40 located inside the transmission case 6.
To the input shaft 41 via the gear mechanism 19, and the rotational power of the output shaft 42 of the auxiliary transmission 40 for traveling is output to the rear end of the output shaft 42 in the form of an integrated rear wheel output gear 43. A front wheel output gear 44 which is rotatably attached to the rear end of the output shaft 42 to the rear wheel differential mechanism 7B via
The transmission is transmitted to the front wheel differential mechanism 7A via a front wheel transmission shaft 7C whose rear end is linked to the front wheel output gear 44 via a gear mechanism.

The sub transmission 40 for traveling is constructed as follows. A low-speed gear 45a, a medium-speed gear 45b, and a high-speed gear 45c are integrally provided on a transmission shaft 41a that is integrally rotatably connected to the input shaft 41 by a coupling, and among these gears 45a, 45b, 45c, The low-speed transmission gear 46 is provided on the output shaft 42 so as to be rotatable relative to the high-speed gear 45a and the high-speed gear 45c.
a, the high speed transmission gear 46c is always engaged. The low-speed transmission gear 46a and the high-speed transmission gear 46c each have a transmission external gear on the outer periphery of each boss portion, and the low-speed transmission gear 46a and the high-speed transmission gear 4c.
6c, on the output shaft 42 at an intermediate position with respect to the output shaft 42 so as to be integrally rotatable and slidable by spline engagement, and
At both ends thereof, there is provided a shift gear 46b formed with an internal gear that meshes with a transmission external gear formed on the outer periphery of each of the bosses of the low speed transmission gear 46a and the high speed transmission gear 46c. Therefore, the shift gear 46b is operated to one side in the axial direction to engage with the low-speed transmission gear 46a, the shift gear 46b is operated to the other side to engage with the high-speed transmission gear 46c, It is configured to be switchable between a position and a state where it is engaged with the medium speed gear 45b on the transmission shaft 41a,
The rotational power from the traveling main transmission 20 is transmitted to the front and rear wheels 1 and 2 by sub-shifting in three stages.

The power take-off shaft 4C is rotatably supported at the rear of the traveling transmission case 6. As shown in FIGS. 3 and 6, the power take-off shaft 4C has an input rotary shaft 22 of the traveling main transmission 20.
From the extension shaft portion 22a of the work mission 5 located inside the traveling transmission case 6 via a shaft coupling.
0 is transmitted from the engine E.
The work mission 50 is provided with the traveling main transmission 2.
The input shaft 51 connected to the extended shaft portion 22a of the rotary shaft 22 for input of 0 through a shaft coupling is used as the input shaft,
A multi-plate type work clutch 52 which can be operated on the input side by supply of pressurized oil, one end of which is connected to an output shaft 53 of the work clutch 52 via a gear mechanism 54, and the other end is integrally rotated with the power take-out shaft 4C by a coupling. It is constituted by a rotating shaft 55 which is connected as much as possible. That is, the rotational output of the engine E is branched from the traveling side and transmitted to the work mission 50 so that the speed does not change regardless of the speed change operation of the traveling main transmission 20 and the auxiliary transmission 40, and transmitted to the work clutch 50. Is transmitted to the power take-out shaft 4C so that the connection / disconnection operation can be performed.

[Case Block] The case block 10 constituting the intermediate vehicle body 5 for connecting the front vehicle body 3 and the rear vehicle body 4 with the above-described transmission structure installed therein is constructed as follows. As shown in FIGS. 4 to 8, the case block 10 of the traveling main transmission 20 includes a shift block portion 1 that forms a case wall of the hydraulic pump P and the hydraulic motor M.
1 and a large-diameter bowl-shaped part 12 integrally formed with an upper edge higher than the upper surface of the speed-change block part 11, and the periphery of the large-diameter bowl-shaped part 12 A flange portion connected to the rear portion of the flywheel housing portion 3D located at the rear portion is formed, and an accommodation space S1 capable of accommodating the main clutch 9 is formed inside the recess of the large-diameter bowl-shaped portion 12. It is. The upper surface of the transmission block portion 11 that forms the case wall of the hydraulic pump P and the hydraulic motor M of the traveling main transmission 20 and the upper edge of the large-diameter bowl-shaped portion 12 including the housing space S1 for the main clutch 9. The interval between the inclined wall portions 12 is such that the case sectional shape gradually changes.
A clutch-side transmission shaft 17 extending from the main clutch 9 side and a pump-side rotation shaft 22 extending from the hydraulic pump P side are provided inside a case including the inclined wall portion 12A. A supporting shaft wall 13 is provided.

The wall 13 for supporting the shaft is the most hydraulic pump P
The first partition 14 is located near the hydraulic motor M, the third partition 16 is located closest to the main clutch 9, and the second partition 15 is located in the middle. The first partition 14 includes bearings 14a and 14b that support the front ends of the rotary shafts 22 and 23 of the hydraulic pump P and the hydraulic motor M of the main transmission 20 for traveling.
5 is a transmission gear 1 provided at a shaft end of a pump-side rotary shaft 22 extending to the front side through the first partition 14.
Bearing portion 15b for supporting the rear side of the main clutch 9b
Bearing portion 15 for supporting the rear side of a transmission gear 18a provided at the rear end side of a transmission shaft 17 extending from the side thereof.
a. The third partition 16 is provided with a bearing 16 for supporting the front sides of the transmission gears 18a and 18b.
a, 16b, and the two transmission gears 18a,
18b is constituted by a lid member that partitions the arrangement space S2 from the accommodation space S1 on the side where the main clutch 9 is present, and this lid member is configured to be detachable from the second partition 15 via a connecting bolt. Have been. In addition, the above-mentioned second partition 1
5 is such that the case cross-sectional shape of the upper surface of the speed change block portion 11 constituting the case wall of the hydraulic pump P and the hydraulic motor M and the large-diameter bowl-shaped portion 12 having the housing space S1 of the main clutch 9 gradually changes. The first partition part 14 is provided near the boundary with the part where the inclined wall part 12A is formed, and the first partition part 14 is formed closer to the speed change block part 11 side.
6 is provided so as to be located on the upper side of the inclined wall portion 12A than the second partition portion 15.

The space S2 for disposing the transmission gears 18a and 18b partitioned by the third partition 16 and the second partition 15 has a communication hole 15c formed in the second partition 15 as shown in FIG. Through the passage space S3 formed between the second partition 15 and the first partition 14. Further, the passage space S3 is connected to the traveling main transmission 20 through an opening 14c formed near the upper portion of the first partition 14.
Is connected to the transmission room space S4 in which is disposed. That is, the space S2 for disposing the transmission gears 18a and 18b
, The passage space S3, and the transmission space S4 are configured as a common space through which hydraulic oil can flow, and are disconnected from the housing space S1 of the main clutch 9 to which hydraulic oil is not supplied. ing. As shown in FIGS. 6 to 8, the speed change block portion 11 is made of a cast iron case peripheral wall 21.
And the case peripheral wall 21 on the rear end face side of the case peripheral wall 21.
Formed in a block shape by a cast iron port block 21P bolted to the rear end face of the flange portion 11A formed on the rear end face thereof so as to be bolted to the traveling transmission case body 6A and connected to the inside thereof. I have. The port block 21P is configured to enter the inside of the traveling mission case main body 6A when the case block 10 is connected to the traveling mission case main body 6A, as indicated by a virtual line in FIG. I have.

The rotary shaft 2 on the hydraulic pump P side corresponds to the shaft center P1 of the transmission shaft 17 extending from the main clutch 9 side.
The shaft center P2 of the rotating shaft 23 on the hydraulic motor M side is disposed below the shaft center P1 and offset to one side in the left-right direction. Rotary axis 2
It is disposed below the second shaft center P2 and offset to the other side in the left-right direction with respect to the shaft center P2 of the rotary shaft 22 on the hydraulic pump P side. By adopting such an arrangement configuration, the vertical distance between the two shaft cores P1 and P2 is reduced even slightly, as compared with a structure in which the shaft core P2 is disposed vertically below the shaft center P1, and the shaft center P1 On the other hand, the axis P2 can be positioned closer to one side in the left-right direction (the left side of the machine in this embodiment). As a result, the vertical dimension of the entire case block can be reduced as much as possible, and the axis P2 of the hydraulic motor M is shifted from the axis P1 to the other by shifting the axis P2 to one of the left and right directions. The amount of deviation to the side can be reduced, which is effective in shortening the overall dimension in the left-right direction. Further, in the relationship between the shaft cores P2 and P3, the shaft center P3 of the rotary shaft 23 on the hydraulic motor M side is disposed below the shaft center P2 of the rotary shaft 22 on the hydraulic pump P side. Therefore, the size in the left-right direction can be reduced as compared with the case where the case block 10 is provided in the horizontal direction, and this is also effective in reducing the size and weight of the case block 10.

As shown in FIGS. 4, 5 and 7, the bottom of the case block 10 has a through hole 3 penetrating in the front-rear direction.
8 are formed, and the front wheel transmission shaft 7C is formed in the through hole 38.
And the ground height of the front wheel transmission shaft 7 </ b> C is raised to near the lower edge of the large-diameter bowl-shaped portion 12.

[Traveling Main Transmission] The traveling main transmission 20 comprises a variable displacement hydraulic pump P driven by the input shaft 22 as a drive shaft, as shown in FIGS. A constant displacement hydraulic motor M driven by pressure oil from P and having the output rotary shaft 23 as an output shaft is provided inside the speed change block portion 11. Thereby, the traveling main transmission 2
0 is located near the rear of the main clutch 9 and converts the engine output transmitted to the input rotary shaft 22 into forward drive force and reverse drive force by the hydraulic pump P and the hydraulic motor M. The traveling main transmission 20 is configured to continuously change the speed on both the forward side and the reverse side and to transmit the transmission from the output rotary shaft 23 to the traveling auxiliary transmission 40. The details are configured as follows.

The transmission block portion 11 includes a cast iron case peripheral wall 21 that accommodates the hydraulic pump P and the hydraulic motor M together with hydraulic oil, and a cast iron port block 21P bolted to the rear end surface of the case peripheral wall 21. And are formed in a block shape. At the rear end of the case peripheral wall 21, a flange portion for bolt connection to the traveling mission case body 6A constituting the rear vehicle body 4 is formed. In the port block 21P,
A bearing portion for rotatably supporting the output shafts 22 and 23 of the hydraulic pump P and the hydraulic motor M is provided, and the hydraulic oil is circulated between the hydraulic pump P and the hydraulic motor M. An oil passage is formed to allow the oil to flow.

The hydraulic pump P and the hydraulic motor M are housed side by side in the transverse direction of the vehicle body in a transmission room space S4 formed by an oil chamber inside the case peripheral wall 21. The hydraulic pump P is a cylinder block 2 having a plurality of plungers 25 slidably disposed around the input shaft 22.
6 is rotated by the input shaft 22 around its axis, and the ring-shaped swash plate 27 fitted to one end of the input shaft 22 swings with respect to the transmission block portion 11. An axial plunger pump is configured. The hydraulic motor M controls the cylinder block 29 so that the cylinder block 29 including a plurality of plungers 28 slidably disposed around the output rotary shaft 23 rotates integrally with the output rotary shaft 23. Axial plunger motor such that the plunger 28 reciprocally slides with respect to the cylinder block 29 by the action of a swash plate 30 provided integrally with the case peripheral wall 21 inside the transmission block portion 11 as the shaft rotates. It is configured in. The cam surface 30a of the swash plate 30 of the motor M
Is formed by a cam plate attached to the swash plate 30, and is formed on an inclined surface which is inclined so as to be located on the rear side of the vehicle body toward the outside of the vehicle body.

As shown in FIG. 6, the two suction ports 31 of the hydraulic pump P are arranged side by side in the lateral direction of the vehicle body, and the inner side of the port block 21P and a valve plate 32 fixed to the inner side.
And the two suction and discharge ports 3 of the hydraulic motor M
The inner surface of the port block 21P is arranged such that the motor-side intake / exhaust port 33 is arranged in the vehicle vertical direction such that the direction of the motor-side intake / exhaust port 33 parallel to the vehicle body is different from the direction of the pump-side intake / exhaust port 31 of the parallel direction. Valve plate 34 fixed to the inner side
And one suction port 31 on the pump side and one suction port 33 on the motor side are connected to the hydraulic port block 21.
P and connected by an oil passage drilled in
1 and the other suction / discharge port 33 on the motor side are configured to be connected by another oil passage formed in the hydraulic port block 21P, so that circulation of the hydraulic oil between the hydraulic pump P and the hydraulic motor M is performed. Is performed.

As shown in FIGS. 6 to 11, a set of cylinder assembling parts 21b provided by integral molding with the case peripheral wall 21 on a lateral side of the transmission block portion 11 where the hydraulic pump P is located. A hydraulic servo cylinder 61 assembled in the mounting hole with the cylinder longitudinal direction along the vehicle body vertical direction, and mounted on the outer surface side of the cylinder mounting portion 21b with the valve longitudinal direction along the vehicle body vertical direction. With the hydraulic servo valve 62, the hydraulic pump P
Of the swash plate angle is configured. That is, as shown in FIG. 10 and FIG.
The operation lever 63 is supported by a valve case 65 via a rotation support shaft 64. When the operation lever 63 is swung about the axis of the rotation support shaft 64, the rotation support shaft 64 rotates together with the operation lever 63, and an operation portion 66 extending from the rotation support shaft 64 inside the valve case 65. The connection pin 66 swings around the axis of the rotation support shaft 64 and engages the operation portion 66 with one end of the valve operation link 67.
a, the valve operation link 67 is connected to the servo cylinder 61
The swing operation is performed with the other end side engaged with the swing support as the swing fulcrum.
Then, the connecting pin 67a connecting the intermediate portion of the valve operation link 67 to the valve spool 68 moves from the neutral position in the same direction as the moving direction of the connecting pin 66a, and switches the valve spool 68 from the neutral position to the drive side. To operate, the servo cylinder 61 is driven by pressure oil,
As shown in FIG.
The swash plate 27 is swung toward the speed increasing side or the decelerating side on the forward side or the reverse side corresponding to the operation direction of the operation lever 63 by the operation pin portion 61a engaged with the operation lever 7. The servo cylinder 61 swings the swash plate 27 while swinging the valve operation link 67 with the connection pin 66a as a swing fulcrum,
When the angle at which the swing of the swash plate 27 changes reaches an angle proportional to the operation stroke of the operation lever 63, the connection pin 67
"a" returns to the neutral position, and returns the valve spool 68 to the neutral position. Thus, when the angle of the swash plate 27 changes in a direction corresponding to the operation direction of the operation lever 63 by an angle proportional to the operation stroke of the operation lever 63, the servo valve 62 automatically returns to the neutral state, and the servo cylinder 61 Stops, and the swing operation of the swash plate 27 is stopped.

[Hydraulic Circuit] A hydraulic supply circuit for supplying charge pressure to the main traveling transmission 20 is configured as follows. As shown in FIG. 12, the supply oil from the pressure oil supply pump PO driven by receiving the engine power is supplied to the supply oil passage r1 on the power steering operation device PS side via the regulator valve V1, and the traveling main transmission. It is configured to be distributed and supplied in two directions: the 20 servo cylinders 61 and the supply oil passage r2 on the PTO clutch 52 side.
That is, about 150 kg / cm ² of pressure oil is discharged from the pressure oil supply pump PO, and about 140 kg of pressure oil is supplied to the power steering operation device PS by the regulator valve V1.
/ Cm ² , about 25 kg / cm to the flow path on the servo cylinder 61 side
^2, and the distribution pressure is set to the appropriate pressure of each operating device to supply the pressure oil. To the charge pressure supply passage r4 to traveling main transmission 20, the above still lower pressure than the set pressure (about 10 kg / cm ²⁾ it is desirable, and, the required flow rate tends not constant. Therefore, if an attempt is made to provide a supply path in which a dedicated charge pressure is set from the side of the pressure oil supply pump PO, not only a regulator valve and a dedicated oil path are required, but there is also a loss that requires extreme pressure reduction. Although it is inconceivable to take out the charge pressure by reducing the pressure from the supply oil passage r2 of the servo cylinder system which is relatively close to the set pressure, it is originally supplied to the supply oil passage r2 of the servo cylinder system. The pressure oil flow is small, and the servo cylinder system becomes unstable if the required amount is not supplied for its operation. The operation of the cylinder 61 and the PTO clutch 52 may be unstable, which is not preferable.

In the present invention, a relatively large flow rate is supplied.
Power steering operating device PS has its return oil passage r
Focusing on the possibility of lower pressure in 3
So that the charge pressure can be taken out from the return oil passage r3.
Main relief valve for setting charge pressure in return oil path r3
RM, and set the relief pressure to match the above pressure.
By setting so that power steering operation device
The return pressure from the PS is used to charge the traveling main transmission 20.
It can be used as. In other words, power
-Supply of supply oil passage r1 to steering operation device PS
Side pressure is the discharge pressure from regulator valve V1
(About 140kg / cm^Two) Is supplied, but the power
Circuit due to increased operation resistance on the steering operation device PS
When the pressure increases, a relief pressure equivalent to the discharge pressure
Via the set relief valve RP for steering pressure setting
Then, it can escape to the return oil passage r3. Power steering
The operation valve V2 of the ring operation device PS is neutral as shown in the figure.
Is in a position (straight running without steering operation)
At this time, the pressure oil in the supply oil passage r1 flows through the operation valve V2.
It flows through the vertical port to the return oil passage r3, and the return oil passage r3
Main pressure relief valve RM for setting charge pressure
Set pressure (about 10kg / cm ^Two)become.

The supply of the charge oil from the return oil passage r3 to the pressure oil circulation passage of the traveling main transmission 20 is performed by the return oil passage r which is located on the more upstream side than the main relief valve RM for setting the charge pressure.
This is performed via a charge pressure supply path r4 branched from the third path. The traveling main transmission 20 is provided with a charge relief valve RC for performing a relief operation at a pressure higher than the charge pressure setting main relief valve RM. , One side (from the hydraulic pump P side to the hydraulic motor M side) of the pressure oil circulation path becomes high pressure in relation to the rotation direction of the hydraulic pump and the hydraulic motor M, and the other side (from the hydraulic motor M side to the hydraulic pump P). Side) becomes low pressure. The charge relief valve RC is configured by a pair of a charge relief valve RC in which an oil passage direction is set to be opposite to an oil passage that connects the high-pressure side passage and the low-pressure side passage, and a check valve. A charge oil introduction valve mechanism is provided, and the pressure oil supplied from the charge pressure supply path r4 passes through a check valve connected to the low-pressure side flow path of the pressure oil circulation path of the traveling main transmission 20. It is supplied to the pressure oil circulation path. When a high load acts on the hydraulic motor M and the high pressure side flow path of the pressure oil circulation path becomes higher than a predetermined pressure, the charge relief valve RC on the side connected to the high pressure side flow path and the low pressure side flow path And a short-circuit of the pressure oil from the high-pressure side to the low-pressure side through a check valve allowing the passage of pressure oil. The return oil passage r
The return oil that has passed through the main relief valve RM for setting the charge pressure of No. 3 is cooled by the oil cooler OC, and then part of the return oil is supplied to the regulator valve V1 side, and the other is sucked by the pressure oil supply pump OP. It is configured to be supplied to the mouth, and is configured to circulate the return oil during operation without returning it to the hydraulic oil tank. As shown in FIGS. 6 to 9, the main relief valve RM and the charge relief valve RC for setting the charge pressure are formed with holes in the side wall portion of the speed change block portion 11 to be integrated with the side wall. The valve body and the urging spring are mounted in the valve case formed in the above, and the set pressure can be freely adjusted by changing the spring pressure for urging the valve by screw operation from outside. In FIG. 12, PSC is a power steering cylinder, and F1 and F2 are filters.

[Shift operation mechanism] The main transmission 2 for traveling
Reference numeral 0 denotes a configuration in which a shift operation is performed by a shift operation mechanism 70 including a shift pedal device 71 provided on a deck 69 of the driving section. The speed change operation mechanism 70 transmits the operation of the speed change pedal device 71 to the operation lever 63 of the servo valve 62, and is configured as shown in FIGS.

That is, the speed change pedal device 71 is
As shown in the figure, the forward operation tread surface 72a moves forward and the rearward operation tread surface 73a cooperates with each other. A pair of front and rear operation pedals of a forward operation pedal 72 and a reverse operation pedal 73 formed such that the forward operation tread surface 72a is deviated laterally outward from the reverse operation tread surface 73a so as to facilitate the stepping operation. 7
2 and 73, and a linking member 74 formed of a turnbuckle for connecting the operation pedals 72 and 73 mechanically and in an adjustable length.
The forward operation pedal 72 of the transmission pedal device 71 is configured such that the traveling main transmission device 20 is connected to the forward operation pedal 72 in a side view of the vehicle body.
When the forward operation portion 72a of the speed change pedal device 71 and the rear end of the traveling main transmission 20 overlap in the vehicle front-rear direction in a state of being located forward of the rocking fulcrum 72b of the vehicle, A shaft core 72b as the swing fulcrum provided
It is supported to swing around. The operation arm 72c on the opposite side of the forward operation tread surface 72a across the swing fulcrum 72b of the forward operation pedal 72 is connected to the operation arm 72c via a length-adjustable operation member 75 formed of a turnbuckle. An operation lever 63 of the servo valve 62 provided on a lateral side surface of the case block 10 is interlocked and connected. Thus, the forward operation pedal 72 and the operation lever 63 are linked so that the servo valve 62 operates based on the pedal operation. The reverse operation pedal 73 of the speed change pedal device 71 is swingably mounted around a swing fulcrum 73b provided on the rear side of the fuselage with respect to the forward operation pedal 72 in a side view of the vehicle body. The operation arm portion 73c on the opposite side to the reverse operation tread surface 73a between the operation arms 73c.
Is connected to the operating arm 72c of the forward operating pedal 72 via the linking member 74. by this,
The reverse operation pedal 73 is also linked with the operation lever 63, and is linked so that the servo valve 62 operates based on the pedal operation.

The swing fulcrum 73b of the reverse operation pedal 73
Is constituted by a shaft 76 that penetrates the traveling transmission case 6 in the left-right direction, and the reverse operation pedal 73 and the shaft 76 are integrally and rotatably linked to each other. Then, on the lateral side surface of the traveling transmission 6 opposite to the side where the transmission pedal device 71 and the servo valve 62 are provided, the traveling transmission 6 is connected to the penetrating shaft body 76 with respect to the traveling hydraulic transmission device 20. A neutral return mechanism 80 and a so-called cruise device 90 that artificially maintains the speed change pedal device 71 in a constant depressed state are provided.

As shown in FIG. 14, the neutral return mechanism 80 includes a bifurcated swing member 81 which is integrally and rotatably attached to the penetrating end of the shaft 76, and the swing member. 8
1, a rod 82 rotatably linked to the cam 1, a cam body 83 linked rotatably to an end of the rod 82, and a cam pressed against the cam body 83 A cam follower 85 having rollers 84 and an urging tool 86 for urging the cam follower 85 against the cam body 83 are provided. The cam body 83 is pivotally mounted around a pivot shaft 87 provided on the side surface of the traveling transmission 6 and has a cam surface 83a having a concave portion at an intermediate portion in the rocking direction. Fan cam 8 with
3A and a swing link 83B pivotally attached to the pivot shaft 87 so as to be able to swing integrally with the fan-shaped cam 83A. The free end of the swing link 83B is connected to the rod 82, The cam body 83 is configured to swing around the pivot shaft 87 as the swing member 81 swings. The cam follower 85 is provided with a cam roller 84 at a longitudinally intermediate portion of a swinging rod pivotally attached around a pivot 88 provided on a side surface of the traveling transmission 6.
It is configured to be rotatable around 4a. The urging member 86 is constituted by a coil spring having one end locked to the free end of the cam follower 85 and the other end fixed to the lateral side surface of the traveling transmission. When the traveling main transmission 20 is operated in a neutral state by pressing against the surface 83a side and the cam body 83 is in a state in which the cam roller 84 is positioned in a recess formed in the cam surface 83a. It is configured to be in a stable position. In the figure, reference numeral 89 denotes a damper, one end of which is connected to the cam follower 85, and the other end of which is pivotally connected to the lateral side of the traveling transmission. As a result, even if vibration is transmitted from the swash plate 27 of the traveling main transmission 20 to the operation lever 63 and the transmission pedal device 71, the damper 89 damps the cam follower 85 and the vibration of the transmission pedal device 71 and the operation lever 63. Attenuate. Further, the shift pedal device 71 is connected via the cam follower 85 and each linking means connected thereto.
To prevent the speed change pedal device 71 from being operated quickly.

That is, when the forward operation tread surface 72a of the speed change pedal device 71 is depressed from the neutral position, this operation force is transmitted to the operation lever 63 by the speed change operation mechanism 70, so that the operation lever 63 swings forward in the vehicle body. The servo valve 62 is switched to the forward side, and the main transmission 2
0 switches from the neutral state to the forward side. As a result, the vehicle body moves forward. When the forward operation tread surface 72a is further depressed, the sloshing of the operation lever 63 toward the front of the vehicle body becomes large, and the swash plate change angle by the servo cylinder 61 becomes large. Shifts to a higher speed. As a result, the vehicle forward speed increases. When the reverse operation tread surface 73a of the speed change pedal device 71 is depressed from the neutral position, this operation force is transmitted to the operation lever 63 by the interlocking mechanism 77, so that the operation lever 63 swings rearward of the vehicle body and the servo valve 62 moves backward. Side, and the traveling main transmission 20 switches from the neutral state to the reverse side. As a result, the vehicle body runs backward. As the reverse operation tread 73a is further depressed,
The swing throat of the operation lever 63 toward the rear of the vehicle body increases, the swash plate change angle by the servo cylinder 61 increases, and the traveling main transmission 20 shifts to a higher speed side. As a result, the vehicle reverse speed increases. In either case during forward or backward travel, when the depressing operation on the shift pedal device 71 is released, the shift pedal device 71 is also operated by the operating lever 63 due to the neutral restoring action of the neutral return mechanism 80.
Automatically moves toward the neutral position, and the traveling main transmission 20 shifts to the deceleration side. As a result, the vehicle running speed decreases. Finally, the transmission pedal device 7
Both 1 and the operating lever 63 are restored to the neutral position, and the traveling main transmission 20 returns to the neutral state. This stops the vehicle running. At this time, both the operation lever 63 and the transmission pedal device 71 are stably held at the neutral position because of the damping action by the damper 89 and the positioning action by the neutral return mechanism 80.

The cruise device 90 is configured as follows. A bar-shaped linking rod 91 is provided on a portion of the fork-shaped swinging member 81 attached to the shaft body 76 penetrating the traveling transmission 6, at a position different from the side to which the rod 82 is connected. At the tip of the link rod 91, a general swing operation tool and its swing position are frictionally fixed,
A well-known position holding device 92 configured to be switchable between the fixed state and the unlocked state is provided, and a cruise device 90 is configured by the position holding device 92 and the link rod 91. Accordingly, the link rod 91 is pushed and pulled in accordance with the swing operation by the swing operation tool provided in the position holding device 92, and is frictionally fixed at that position, whereby the servo cylinder 61 linked to this is rotated. The position can be maintained.

[Another Embodiment] The arrangement relationship between the hydraulic pump P and the hydraulic motor M in the traveling main transmission 20 is such that the hydraulic motor M is lower than the hydraulic pump P as shown in the embodiment. However, the present invention is not limited thereto, and they may be arranged in a state where they are located at substantially the same level. The speed change pedal device 71 is not limited to the one constituted by the pair of front and rear operation pedals 72 and 73 as shown in the embodiment, but is constituted by one operation pedal having treads on each of the front part and the rear part. May be done. The charging pressure setting main relief valve RM and the charging relief valve RC may be configured to be detachable from the side wall portion of the speed change block portion 11.

[0034]

In the vehicle body structure of the working vehicle according to the present invention, a large-diameter bowl having a space for accommodating the main clutch is provided with respect to a transmission block portion constituting a case wall of a pump and a motor of a hydrostatic continuously variable transmission. Since the parts are integrated, the connection strength is increased by synergistically increasing the contact area of the connection point with the front vehicle body and reducing the number of connection points by one when compared with connecting the clutch housing separately. Improvement and
There is an advantage that the number of connection steps can be reduced. Also, where the case block is connected to the front vehicle body, the connection with the transmission shaft is not made with extremely high precision, such as fitting and connecting the pump input shaft near the bearing fixed to the case. A relatively flexible connection in terms of assembling accuracy, that is, power transmission with the main clutch constituent members, can be achieved, and simplicity in assembling processing can be expected. By adopting the above configuration, according to the present invention, the case block has a shaft supporting wall inside the case block, and the wall having a large dimension in the front-rear direction so that the shaft supporting wall forms the interior space of the transmission gear. Since it is configured, there is an advantage that the strength weak point portion due to the change in the case cross-sectional shape is satisfactorily reinforced and the strength of the case block itself is improved. Further, the space for gear arrangement formed in the shaft supporting wall portion is communicated with the space in the transmission room where the pump and motor of the hydrostatic continuously variable transmission are present, thereby enabling the flow of hydraulic oil. The oil passage piping from the hydrostatic continuously variable transmission to the gear installation space and the oil passage piping from the gear installation space to the transmission room space can be omitted, and the lubricating oil passage can be reduced without requiring a complicated piping structure. In addition to being able to configure, the space for gear disposition and the space for the gearbox are substantially integrated to increase the space volume, so the lubricating oil temperature rises rapidly only in the narrow space for gear disposition. Is easy to avoid,
There is an advantage that deterioration of the lubricating oil is easily suppressed.

According to the second aspect of the invention, the return oil of the hydraulic oil supplied to the hydrostatic continuously variable transmission is supplied to the suction port of the pressure oil supply pump via the oil cooler without returning to the hydraulic oil tank. However, there is an advantage that the life of the oil filter and various hydraulic devices can be extended by maintaining the cleanliness and cooling state of the return oil from the hydrostatic continuously variable transmission. Further, when the hydraulic oil is supplied to the suction port of the pressure oil supply pump without returning to the tank, the generation of air bubbles in the hydraulic oil is less likely to occur, and there is little possibility that air is caught.

[Brief description of the drawings]

FIG. 1 is an overall side view of an agricultural tractor.

FIG. 2 is a side view showing an outer shape of a vehicle body component.

FIG. 3 is a schematic diagram showing a power transmission system.

FIG. 4 is a vertical sectional view of a case block portion.

FIG. 5 is a front view of a case block portion.

FIG. 6 is a horizontal sectional view of a case block portion.

FIG. 7 is a rear view of a case block portion.

FIG. 8 is a side view of a case block portion.

FIG. 9 is a partial sectional view of a charge valve portion;
(A) is the main relief valve for setting the charge pressure, (b)
Indicates a charge relief valve.

FIG. 10 is a sectional view of a servo valve operating unit.

FIG. 11 is a sectional view of a servo valve.

FIG. 12 is a hydraulic circuit diagram.

FIG. 13 is a side view of a shift pedal and a shift operation mechanism.

FIG. 14 is a side view showing the neutral return mechanism and the cruise device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 front body 4 rear body 5 intermediate body 6 traveling transmission case 9 main clutch 10 case block 11 transmission block part 12 large-diameter bowl-shaped part 12A inclined wall part 13 shaft support wall part 14 first partition part 15 second partition Part 16 Third bulkhead 20 Hydrostatic stepless transmission 70 Gearshift operating mechanism 71 Transmission pedal device 80 Neutral return mechanism 90 Cruise device P1 Shaft core of transmission shaft from main clutch P2 Shaft core of hydraulic pump side P3 Hydraulic motor side Axis of

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62D 49/00 B62D 49 / 00Z (72) Inventor Isamu Morimoto 64 Ishizukita-cho, Sakai-shi, Osaka Kubo Co., Ltd. Inside the Sakai Plant (72) Inventor Atsushi Shinkai 64 Ishizukitamachi, Sakai City, Osaka Prefecture Inside the Kubota Sakai Plant (72) Inventor Yasunobu Nakatani 64 Ishizukitamachi, Sakai City, Osaka Prefecture (Reference) 3D033 EB04 EB05 EB07 EB10 3D039 AA02 AA04 AA14 AA16 AB11 AB21 AC03 AC13 AC65 AC67 AD05 AD33 AD43 3D042 AA07 AB07 BA02 BA05 BA19 BB03 BC01 BC08

Claims (2)

[Claims] 1. A main clutch and a hydrostatic stepless transmission that intermittently drive engine power are interposed between a front vehicle body equipped with an engine and a rear vehicle body equipped with a gear transmission. A working vehicle in which a case block of a hydraulic continuously variable transmission is used as a vehicle body component for connecting a front vehicle body and a rear vehicle body, wherein the case block of the hydrostatic continuously variable transmission is a hydrostatic type continuously variable transmission. The large-diameter bowl-shaped part is formed integrally with the upper edge of the transmission block part constituting the case wall of the pump and the motor of the continuously variable transmission so as to be higher than the upper surface. A housing space is formed, and a shaft support wall portion is provided inside the case block for supporting a clutch-side transmission shaft extending from the main clutch side and a pump-side rotation shaft extending from the pump side. With the shaft support wall Inside, a transmission gear provided at the shaft end of the clutch-side transmission shaft and a transmission gear provided at the shaft end of the pump-side rotation shaft are formed in a gear disposition space for receiving the gear in a meshing state, And a work vehicle in which the space for disposing the gear and the space in the transmission block where the pump and the motor of the hydrostatic continuously variable transmission are located communicate with each other so that hydraulic oil can flow. . 2. The return oil of the hydraulic oil supplied from the hydraulic oil supply pump to the hydrostatic stepless transmission is supplied to the suction port of the hydraulic oil supply pump via the oil cooler without returning to the hydraulic oil tank. Work vehicle configured to be.