JP4282023B2 - Work vehicle transmission - Google Patents

Description

  The present invention relates to a transmission in a working vehicle to which a working device such as a tiller or a mower device is attached.

  In a vehicle equipped with a working device such as a bucket, a tiller or a mower device in the front, rear and / or lower center of the chassis, the driving force from the driving source is branched into the traveling system transmission path and the working apparatus system transmission path. Each of them needs to be transmitted to the drive wheel and the working device, and there is a problem that the transmission becomes large.

As a structure for preventing an increase in the size of a transmission applied to such a vehicle, for example, there are those described in Japanese Patent Publication No. 1-17883 and Japanese Utility Model Publication No. 1-337298.
In the transmissions described in the above publications, the PTO system input shaft and the travel system input shaft are arranged in parallel in the vertical direction, and the work system transmission path and the travel system transmission path are provided as much as possible above and below the transmission case, respectively. The transmission is miniaturized by disposing it.

  By the way, when the working device as described above is provided, in addition to taking out a driving force for driving the working device, a hydraulic device for operating the working device may be required. As such a hydraulic device, for example, there is a hydraulic lift device for raising and lowering a tiller attached to the rear of the chassis.

  As described above, the publication described in the above publication can reduce the size of the transmission by consolidating the traveling system transmission path and the work apparatus drive transmission path in the lower and upper directions in the transmission case, respectively. However, no consideration is given to downsizing with the hydraulic device.

  That is, in the vehicle described in the publication, a hydraulic device for operating a working device such as a tiller is disposed on the upper surface of the transmission case, and a hydraulic pump for supplying pressure oil to the hydraulic device is provided. It is supported by the rear wall of the mission case.

  Therefore, the hydraulic oil for the hydraulic device goes around the rear of the mission case from the state stored in the mission case, and then is transferred to the upper surface of the mission case.

As described above, the transmission structure in the conventional work vehicle can achieve a certain size reduction, but the hydraulic oil supply structure to the hydraulic device has not been considered.
Japanese Patent Publication 1-17883 No. 1-337298

  The present invention has been made in view of the prior art, and in a transmission having a working device transmission path and a traveling transmission path, it is possible to reduce the size of the transmission with a hydraulic pump for operating the working device. The purpose is to provide a transmission.

In order to achieve the above object, the present invention provides a transmission for a working vehicle that branches and transmits a driving force from a driving source to a working device and a driving wheel, the transmission case being spaced apart from the driving source in the longitudinal direction of the vehicle. An HST coupled to the front surface of the transmission case so that the pump shaft and the motor shaft are arranged vertically along the longitudinal direction of the vehicle and in the center of the transmission case in the vehicle width direction, and coaxial with the pump shaft. A PTO system input shaft supported by the transmission case at a substantially center in the vehicle width direction so as to be coupled to the pump shaft, and a substantially center in the vehicle width direction so as to be coupled to the motor shaft coaxially with the motor shaft. And a travel system input shaft supported by the transmission case below the PTO system input shaft, and travel following the travel system input shaft. ON / OFF for power transmission from the PTO system input shaft to the PTO system transmission shaft, a traveling system transmission mechanism including the transmission shaft, a PTO system transmission mechanism including a PTO system transmission shaft following the PTO system input shaft A PTO clutch device, a valve unit that controls pressure oil supply / discharge to a hydraulic device for operating the working device, and an auxiliary pump that supplies pressure oil to the valve unit, and the valve unit is connected to the transmission case. The transmission case is supported on one side upward in the vehicle width direction at the front, the auxiliary pump is supported on the other side in the vehicle width direction on the front of the transmission case, and overlaps the valve unit with respect to the vehicle longitudinal direction position. the and through the provided auxiliary pump Den motive structure above said PTO power transmission mechanism in the vehicle width direction the other side Providing TO system working vehicle transmission which is transmitting the rotational power to the auxiliary pump from the front side of the PTO clutch device of the input shaft.

Preferably, the transmission case is takeout stored fluid for extracting oil stored in the inside is provided on the front, before Symbol auxiliary pump is fluidly connected to the takeout said stored fluid through the external pipe.

The working vehicle transmission further may comprise a through interpolated line filter over between the before and Symbol auxiliary pump HST.
In such embodiments, preferably, takeout prior Symbol oil reservoir is disposed below the transmission case, the line filter can be supported on the front of the transmission case at a lower position than the HST.

According to the present invention, it is possible to effectively compress the front-rear width and the vertical width of the transmission case while preventing mutual interference between the transmission mechanisms, and to supply hydraulic oil from the auxiliary pump to the valve unit. Thus, it is possible to reduce the size of the auxiliary pump, the size of the vehicle, and the reaction speed of the hydraulic device.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a side view schematically showing a vehicle 100 to which the present embodiment is applied.

  As shown in FIG. 1, the vehicle 100 can be provided with working devices such as a bucket device 111, a mower device 112, and a tiller (not shown) at the front, lower center, and rear, respectively. . In the following description, a work device such as a mower device 112 disposed immediately in front of the transmission 30 is referred to as a first work device, and a work device such as a tiller disposed behind the transmission is referred to as a second work device. Say device.

In the vehicle 100, the engine 10 a, the HST 20, and the transmission 30 are sequentially disposed on the chassis 101 along the longitudinal direction of the vehicle, and the seat 102 is disposed above the transmission 30.
Specifically, the power output from the engine 10a is transmitted from an elastic joint (not shown) attached to the center of rotation of the flywheel 10b via a transmission shaft 10c that has a universal joint at both ends and is inclined downward. And introduced into the input shaft 21a of the HST 20.

1 is a cooling fan installed on the universal joint on the downstream side in the transmission direction of the transmission shaft 10c, and the wind generated by the cooling fan 10d is used in the HST 20 and the transmission case 60. Oil which is stored inside and circulates in the respective parts on the surface is indirectly cooled, and a line filter 68 and an auxiliary pump 420 which will be described later are cooled.
Further, the engine 10a, a radiator and a fuel tank related to the engine 10a are mounted above the front portion of the chassis 101, and these parts are covered with a bonnet.

  A front axle case 10e is suspended below the front portion of the chassis 101 so as to extend along the chassis width direction. Specifically, the left and right end portions of the front axle case 10e are suspended so as to be swingable up and down via a center pin disposed along the front-rear direction at the approximate center in the chassis width direction. A front axle protrudes outward from the left and right ends of the front axle case 10e, and a front wheel is mounted on the front axle.

Further, reference numeral 10f in FIG. 1 is a transmission shaft that connects a front wheel driving force extraction shaft 53a protruding from the front surface of a mission case 60, which will be described in detail later, and an input shaft of the front axle case 10e. The transmission shaft 10f has a substantially horizontal first portion whose rear end portion is connected to the front wheel power take-off shaft 53a via a universal joint, and a rear end portion which is connected to the front end portion of the first portion via a universal joint. And a front end portion connected to the input shaft of the front axle case via a universal joint, and a second portion inclined forward and downward.
The front wheels are driven by rotational power synchronized with the rear wheels 180 via the front wheel power transmission mechanism.
The seat 102 is mounted on a mount stay 10g that extends over the rear upper surface of the mission case 60 and the front surface of a later-described valve unit 410.

  FIG. 2 is a partially exploded perspective view of the HST 20 and transmission 30 portion in the vehicle transmission structure. 3 and 4 show a longitudinal side view and a partial cross-sectional plan view of the HST 20 and the transmission 30, respectively. FIG. 5 is a cross-sectional view taken along line VV in FIG.

  As shown in FIGS. 2 and 3, the HST 20 includes a hydraulic pump body 21 having a pump shaft 21a operatively connected to the engine 10 and disposed along the longitudinal direction of the vehicle, and the pump shaft 21a. A hydraulic motor body 22 having a motor shaft 22a disposed in parallel with the pump shaft 21a below, the hydraulic pump body 21 and a center section 23 for supporting the hydraulic motor body 22, and the hydraulic pump body 21 and the hydraulic motor. And an HST casing 24 connected to the center section 23 so as to surround the main body 22.

The HST 20 is a variable displacement type in which at least one of the hydraulic pump main body 21 and the hydraulic motor main body 22 can change the suction / discharge amount based on an external operation, and the rotation of the motor shaft 22a with respect to the pump shaft 21a. The number can be changed.
Specifically, the HST 20 has an output control arm 25 that controls the rotational output of the motor shaft 22a. The output control arm 25a is operatively connected to a forward / reverse travel pedal (not shown) disposed on a right step (not shown) installed in the chassis 101.

  As shown in FIG. 3, the pump shaft 21a and the rear end of the motor shaft 22a penetrate the center section 23, respectively, and a transmission work device input shaft (PTO system input shaft) 31 and a vehicle which will be described later. It can be connected to a travel input shaft (travel system input shaft) 34.

  FIGS. 6 and 7 respectively show a front view of a mission case 60 to be described later with a front cover 62 removed and a rear view of a mission cover 60 with a rear cover 63 removed. Further, FIG. 8 shows a development diagram of the traveling system drive train along the line VIII-VIII in FIG. FIG. 9 is a development view of the work device drive system (PTO system) drive train of the transmission 30 along the line IX-IX in FIG.

  As shown in FIGS. 3 to 9, the transmission 30 is arranged concentrically with the pump shaft 21 a and is connected to a working device drive input shaft (PTO system input shaft) 31 that is connected to the pump shaft 21 a so as not to rotate relative to the axis. A rear PTO shaft 32 for the second working device, a mid PTO shaft 33 for the first working device, and a PTO system that connects the PTO system input shaft 31, the rear PTO shaft 32 and the mid PTO shaft 33. The transmission system 40, the traveling system input shaft 34 that is concentrically disposed with the motor shaft 22a and connected so as not to rotate relative to the axis, and the traveling system input shaft 34 and a pair of drive wheels are differentially driven. The traveling gear transmission mechanism 50 that connects the ring gear 151 of the differential gear device 150 that performs the transmission, and the transmission case 60 that supports the respective members are provided.

  As shown in FIGS. 3, 5, 8, and 9, the transmission case 60 includes a main body 61 that is open at the front and rear in the vehicle longitudinal direction and one side in the vehicle width direction, and a front opening of the main body 61. And a front lid portion 62 and a rear lid portion 63 for closing the rear opening, respectively, and a side lid portion 64 for closing the side opening of the main body portion 61.

  A work implement mounting hitch 480 is provided at the rear of the mission case 60 to support the second working device so as to be movable up and down. The work implement mounting hitch 480 is swingable to the left and right lower links 482 pivotally supported by the left and right mounting stays 481 mounted on the rear side of the transmission case 60 and the free end of the lift arm 406 described later. And a lift rod 483 whose rear end is swingably connected to the lower link 482 and a mounting bracket 484 whose front end is attached to the upper rear surface of the rear lid 63 (see FIGS. 2 and 3). It is a three-point link type hitch provided with a top link 485 pivotally supported by the frame.

As shown well in FIG. 3, the main body 61 has a front support wall 61a and a rear support wall 61b on the front and rear sides in the longitudinal direction of the vehicle, respectively. Has a storage space.
More specifically, as shown in FIG. 5, the storage space is displaced to one side in the width direction of the transmission case with reference to the traveling system input shaft 34, which will be described in detail later.

The front support wall 61a supports the rear end portions of the PTO input shaft 31 and the travel input shaft 34, respectively, at approximately the center in the vehicle width direction. That is, the PTO system input shaft 31 and the travel system input shaft 34 are both supported by the front lid portion 62 and the front support wall 61a in a state where they are arranged vertically in the approximate center of the vehicle width direction.
More specifically, as well shown in FIGS. 2, 3, and 6, the PTO system input shaft 31 is arranged such that the rotation axis is disposed along the front-rear direction at the approximate center in the width direction of the mission case 60. Further, the front end portion is supported by the front lid portion 62 so as to be connectable to the pump shaft, and the rear end portion is finally supported by the front support wall 61a.

On the other hand, the traveling system input shaft 34 has the front end portion thereof connected to the motor by the front lid section 62 so that the rotation axis is along the front-rear direction at the approximate center in the width direction of the mission case 60 and below the PTO input shaft 31. The rear end portion is supported by the front support wall 61a so as to be connectable to the shaft.
The rear support wall 61b supports the front end portion of the rear PTO shaft 32. In other words, the rear PTO shaft 32 is supported by the rear support wall 61 b and the rear lid portion 63.
More specifically, the rear PTO shaft 32 has the rear support wall 61b at a substantially center in the width direction of the transmission case such that the rotation axis is along the front-rear direction and the rear end portion projects rearward from the rear lid portion 63. And the rear lid 63.

The front lid portion is connected to the main body portion 61 so as to close the front opening of the main body portion 61 and supports the center section 23. That is, the center section 23 is connected to the front lid portion while supporting the hydraulic pump main body 21 and the hydraulic motor main body 22.
In the present embodiment, the front lid portion 62 that closes the front opening of the main body portion 61 is provided. Instead, the front opening of the main body portion 61 is closed by the center section 23. It is also possible to configure.

The mid PTO shaft 33 serves as a drive shaft for the first working device 112 such as a mower disposed below the central portion of the chassis 101. Therefore, the rotation axis is below the transmission case 60 below the vehicle case. The transmission case 60 is supported by the transmission case 60 so as to extend along the direction and have a front end protruding forward from the transmission case 60.
The input shaft 112 (see FIG. 1) of the first working device 112 that is operatively connected to the mid PTO shaft 33 prevents the vehicle height from rising as much as possible and avoids interference with the chassis 101. It is preferable to be displaced from the center in the width direction to either one. In the present embodiment, as described above, differential gear device 150 is housed below one side in the width direction of mission case 60. Accordingly, the input shaft 112 of the first working device 112 is displaced to the other side in the width direction opposite to the side where the differential gear device 150 is displaced, and the mid PTO shaft 33 is also displaced to the other side in the width direction. Is preferred. With such a configuration, a transmission mechanism that suppresses an increase in vehicle height and prevents interference with the differential gear device 150 and connects the mid PTO shaft 33 and the input shaft 112 of the first working device 112. Can be simplified.

In the present embodiment, as shown in FIG. 3, the mid PTO shaft 33 is disposed below the pair of drive shafts 180 in order to bring the mid PTO shaft 33 as close to the ground as possible. ing. With such a configuration, a transmission mechanism that connects the mid PTO shaft 33 and the first working device 112 can be configured without difficulty.
That is, the first work device 112 is configured to be able to take a work state placed on the ground and a standby state where it is lifted up and down from the ground. Therefore, the first working device 112 and the mid PTO shaft 33 are connected by a transmission mechanism having a universal joint. In this case, if the mid PTO shaft 33 is arranged as close to the ground as possible, the folding angle of the universal joint with respect to the mid PTO shaft 33 when the first working device 112 is in a working state can be reduced. A transmission mechanism provided with the universal joint can be configured without difficulty.

  As shown well in FIGS. 3, 6, 7 and 9, the PTO transmission mechanism 40 includes a PTO transmission shaft 41 supported by a transmission case 60 along the longitudinal direction of the vehicle, and the PTO transmission mechanism 41. A PTO clutch device 70 that turns on / off power transmission from the input shaft 31 to the PTO transmission shaft 41; a rear PTO gear train 42 that connects the PTO transmission shaft 41 and the rear PTO shaft 32; A mid PTO transmission gear train 43 connecting between the PTO transmission shaft 41 and the mid PTO shaft 33, and the PTO transmission shaft 41 to the rear PTO gear train 42 and / or the mid PTO transmission gear train 43. And a switching device 45 for turning on / off power transmission.

6 and 9, the PTO transmission shaft 41 is located on the opposite side to the vehicle width direction one side where the differential gear device storage space is displaced with respect to the PTO input shaft 31 as a reference. On the other side in the vehicle width direction, the front support wall 61a and the rear cover portion 63 support the rotation axis along the vehicle front-rear direction and the rear end portion reaching the rear portion of the transmission case 60.
The PTO transmission shaft 41 is a drive shaft for the mid PTO shaft 33 and the rear PTO shaft 32. As described above, the mid PTO shaft 33 is disposed below the mission case 60, while the rear PTO shaft 32 is disposed above the mission case 60. Therefore, in the present embodiment, as shown in FIG. 6, power transmission from the PTO transmission shaft 41 to both the mid PTO shaft 33 and the rear PTO shaft 32 can be performed efficiently and with a simple configuration. The PTO transmission shaft 41 is disposed below the PTO input shaft 31.

The PTO clutch device 70 is disposed in front of the mission case 60 as shown in FIG. That is, in the present embodiment, the power from the PTO system input shaft 31 to the PTO system transmission shaft 41 is turned on / off in front of the mission case 60.
Specifically, the PTO clutch device 70 includes a driving side member 71 supported on the PTO system input shaft 31 so as not to be relatively rotatable and non-slidable in the axial direction, and a driving side friction supported by the driving side member 71. A plate 72, a driven member 73 supported by the PTO system input shaft 31 in a relatively rotatable manner, a driven friction plate 74 supported by the driven member 73 in a non-rotatable and axially slidable manner, A clutch pushing member 75 that frictionally engages the driven side friction plate 74 and the driving side friction plate 72 under the action of hydraulic pressure, and the clutch pushing member 75 is connected to the driving side friction plate 72 and the driven side friction plate. A clutch urging member 76 that is separated from the plate 74 and a PTO transmission gear train 77 that is supported at the front end portion of the PTO transmission shaft 41 so as not to rotate relative to the driven side member 73 are provided.
The PTO clutch device 70 having such a configuration is configured such that when the clutch pushing member 75 frictionally engages both the friction plates 72 and 74 by the action of hydraulic pressure, the PTO system input shaft 31 and the driven member 73 are interposed. As a main PTO gear train that transmits power to the PTO system transmission shaft 41 and as a blocking member that blocks power transmission from the PTO system input shaft 31 to the driven side member 73 when not receiving the action of hydraulic pressure. Function.

  In the present embodiment, the PTO clutch device 70 is further provided with a PTO brake mechanism 80 that is interlocked with the clutch operation of the PTO clutch device 70, so that when the PTO clutch device 70 is powered off, This effectively prevents the rear PTO shaft 32 and the mid PTO shaft 33 from continuing to rotate due to the inertial force of the connected working devices.

  The PTO brake mechanism 80 includes a brake disk 81 supported by the driven member 73 so as not to be relatively rotatable, a brake shoe 82 disposed so as to be frictionally engageable with the brake disk 81, and the brake shoe 82. The brake pushing member 83 supported by the transmission case 60 and the brake pushing member 83 are urged so that the brake shoe 82 can be frictionally engaged with the brake disc 81. The brake shoe 82 is frictionally engaged with the brake disk 81 by the urging force of the brake urging member 84 when the brake pushing member 83 is not subjected to the action of hydraulic pressure. When a braking force is applied to the brake disc 81, and the brake pushing member 83 is subjected to hydraulic pressure, And it moves away from the brake shoe 82 pressing movement member 83 against the biasing force of the brake biasing member 84, so that the braking force to the brake disk 81 is not applied.

  Note that the hydraulic action on the brake pushing member 83 is interlocked with the hydraulic action on the clutch pushing member 75. In other words, when the hydraulic pressure is applied to the clutch pushing member 75 and the clutch device 70 is in the “on” state, the hydraulic pressure is also applied to the brake pushing member 83 and the brake mechanism 80 is operated. Is in the “OFF” state, and on the other hand, when the clutch device is in the “OFF” state without the hydraulic pressure acting on the clutch pushing member 75, the hydraulic pressure acts also on the brake pushing member 83 Without this, the brake mechanism 80 is in the “ON” state.

  The rear PTO gear train is disposed behind the mission case as shown in FIG. More specifically, the rear PTO gear train 42 includes a rear PTO gear member 42a that is rotatably supported in the vicinity of the rear end portion of the PTO transmission shaft 41, and an idle gear 42b that meshes with the gear member 42a. The intermediate shaft 42c that supports the idle gear 42b in a relatively non-rotatable manner and the front end portion of the rear PTO shaft 32 are supported in a relatively non-rotatable manner so as to mesh with a spline 42d provided on the intermediate shaft 42c. And a final gear 42e.

The mid PTO transmission gear train 43 is disposed behind the pair of drive axles 180, as well shown in FIG. That is, the mid PTO transmission gear train 43 is disposed behind the differential gear device 150 so as not to interfere with the differential gear device 150 housed below the mission case 60.
Specifically, the mid PTO transmission gear train 43 includes a mid PTO gear member 43a that is rotatably supported by the PTO transmission shaft 41 so as to face the rear PTO gear member 42a, and the gear member. An idle gear 43b that meshes with 43a, and a final gear 43c that is supported at the rear end portion of the mid PTO shaft 33 so as to be relatively non-rotatable so as to mesh with the idle gear 43b.

The switching device 45 is configured to transmit the rotation of the PTO transmission shaft 41 to the rear PTO gear member 42a and / or the mid PTO gear member 43a by an external operation.
Specifically, the rear PTO gear member 42a and the mid PTO gear member 43a have engaging elements 42a ′ and 43a ′ arranged so as to face each other.
The switching device 45 is supported by the PTO transmission shaft 41 so as not to rotate relative to the rear PTO gear member 42a and the mid PTO gear member 43a so as to be positioned between the engagement elements 42a 'and 43a'. The spline hub 45a is slidable in the axial direction on the spline hub 45a so as to straddle the spline hub 45a and the engaging members 42a 'and 43a' of the rear PTO gear member 42a and / or the mid PTO gear member 43a. The clutch shifter 45b is inserted so as not to rotate relatively, and an arm 45c (see FIG. 7) for operating the clutch shifter 45b is provided.

  As described above, the clutch shifter 45b is extrapolated so as not to rotate relative to the spline hub 45a and the engaging members 42a 'and 43a' of the rear PTO gear member and the mid PTO gear member so as to be non-rotatable and axially movable. The rear PTO output position for connecting the spline hub 45a and the rear PTO gear member 42a so as not to rotate relative to each other in accordance with the axial position, and the spline hub 45a and the mid PTO gear member 43a relative to each other. A mid PTO output position for non-rotatably coupling and a PTO output position for coupling the spline hub 45a, the rear PTO gear member 42a, and the mid PTO gear member 43a for non-rotatable relative to each other can be obtained. ing.

The traveling system transmission mechanism 50 is adjacent to one side in the vehicle width direction of the traveling system input shaft 34 and the rotation axis is along the vehicle longitudinal direction, as well shown in FIGS. 3, 5, 6 and 8. As described above, a transmission shaft (traveling system transmission shaft) 51 supported by the transmission case 60, a multi-stage transmission 52 that performs transmission / disconnection between the traveling system input shaft 34 and the traveling system transmission shaft 51, An optional front wheel power take-out device 53 and a traveling brake device 200 interposed between the transmission shaft 51 and the ring gear 151 of the differential gear device 150 are provided.
The traveling transmission shaft 51 is disposed in front of the differential gear device 150 accommodated on one side in the width direction of the transmission case 60. That is, the traveling system transmission shaft 51 has the same transmission case width direction as that when the differential gear device 150 is displaced with reference to the traveling system input shaft 34 disposed substantially in the center of the transmission case 60 in the width direction. Displaced to one side.

  The multi-stage transmission 52 includes a drive side gear 52a that is supported so as not to rotate relative to the traveling system input shaft 34, and a plurality of (two in this embodiment) driven side gears that mesh with the drive side gear 52a. And a driven member 52b that is supported on the transmission shaft 51 so as not to rotate relative to the transmission shaft 51 and to be slidable in the axial direction, and an operation member (not shown) that moves the driven member 52b in the axial direction of the transmission shaft 51 By engaging one of the driven gears with the driving gear 52a, the driving force can be transmitted from the traveling system input shaft 34 to the traveling system transmission shaft 51 while being shifted.

The front wheel power take-out device 53 is disposed at one front side and the lower side of the transmission case 60 in the front portion of the transmission case 60 with respect to the traveling system transmission shaft 51. That is, the front wheel power take-out device 53 is disposed on the one side in the width direction and below the traveling system input shaft 34 and the traveling system transmission shaft 51 in front of the transmission case 60.
Specifically, the front wheel power take-out device includes a front wheel driving force take-out shaft 53a supported on the lower side in the width direction of the transmission case 60 so that a front end portion extends forward from the transmission case 60, and A gear train 53b with a clutch for connecting the traveling system transmission shaft 51 and the front wheel driving force extraction shaft 53a is provided.

The traveling brake device 200 is configured to be operated by a single brake pedal 205 (see FIG. 1) disposed on the left step provided in the chassis 101.
Specifically, as shown in FIGS. 3, 5, and 8, the traveling brake device 200 includes a brake shaft 201 supported in the transmission case 60 along the vehicle width direction, and the transmission shaft 51. A drive-side bevel gear 202 that is supported at the rear end of the brake-side bevel gear 202 so as to be relatively non-rotatable, a driven-side bevel gear 203 that is supported at the brake shaft 201 so as not to be relatively rotatable, and the ring gear 151. And an output gear 204 provided on the brake shaft 201 and a brake mechanism 210 that stops the rotation of the brake shaft based on an external operation.

FIG. 10 shows a cross-sectional plan view in the vicinity of the brake shaft 201.
As shown in FIG. 10, the brake mechanism 210 includes a drive side friction plate 211 that is supported on the brake shaft 201 so as not to rotate relative to the brake shaft and is slidable in the axial direction, and to face the drive side friction plate 211. It has a driven friction plate 212 that is supported by the transmission case 60 so as not to rotate relative to it, and a pushing surface 213a that faces the driving friction plate 211, and is relatively rotatable and axially movable about the axis of the brake shaft 201. A ring-shaped pushing member 213 supported on the back surface, and a cam groove formed in a back surface 213b opposite to the pushing surface 213a of the pushing member 213, and one circumferential direction side of the pushing member 231 The inclined cam groove 213c formed so as to become deeper as it goes to, the ball 214 disposed in the inclined cam groove 213c, and the front so as to hold the ball 214 immovable. A ball holding recess 215 formed on the inner surface of the brake lid facing the back surface 213b of the push member 213, an inner end portion is connected to the push member 213 via a cam, and an outer end portion is the mission case. 60, a connection arm extending outwardly, the connection arm 216 rotating the pushing member 213 in the circumferential direction by rotation around the axis, and the outer end of the connection arm 216 connected to the outer end. An operation member for the brake pedal 205 (see FIG. 1), and an operation member 217 for rotating the connecting arm 216 about its axis.

  The brake mechanism 210 configured as described above operates the operation member 217 to rotate the push member 213 to one side in the circumferential direction, whereby the ball 214 pushes the push member 213 in the brake axial direction. Thus, the driving side friction plate 211 is frictionally engaged with the driven side friction plate 212, and the rotation of the brake shaft 201 is stopped.

Further, the traveling transmission mechanism 50 includes a differential lock mechanism 250 that locks the differential gear device 150.
The differential lock mechanism 250 revolves around the pair of drive shafts 180 in conjunction with the rotation of the ring gear 151 and meshes with a pair of side bevel gears 152 that are supported on the pair of drive shafts 180 so as not to rotate relative to each other. In this manner, the bevel gear 154 supported on the pivot shaft 153 so as to be relatively rotatable can be forcibly locked around the pivot shaft 153 (see FIG. 5).

  Specifically, as shown in FIGS. 5 and 10, the differential lock mechanism 250 is configured so that the ring gear 151 and one of the pair of side bevel gears 152 are connected to each other so as not to be rotatable relative to each other, and the both are relatively rotatable. A lock member 251 configured to be able to take a release position to be operated, and a differential lock fork shaft supported by the transmission case 60 so as to be movable in the axial direction along the vehicle width direction, and operated from outside the transmission case Diff lock fork shaft 252 that is movable along the axial direction based on the diff lock fork shaft, and a diff lock fork whose base end portion is slidably supported by the differential lock fork shaft 252 in the axial direction and whose distal end portion engages with the lock member 251 253 and a pair of differential lock fork shafts 252 supported by sandwiching the base end of the differential lock fork 253 A first stop member 255a externally inserted into the differential lock fork shaft 252 so as to come into contact with the first and second return springs 254a, 254b and the outer end of the first return spring 254a, the differential lock fork shaft A first stop member 255a configured to move together with the differential lock fork shaft when the 252 moves in one axial direction (locking direction), and an inner end is an outer end of the second return spring 254b. And a second stop member 255b that is externally inserted into the differential lock fork shaft 252 so that the outer end abuts against the inner surface of the side lid portion 64, and the differential lock fork shaft is relatively movable in the axial direction. And a second stop member 255b configured as described above.

The differential lock mechanism 250 having such a configuration operates as follows. That is, when the differential lock fork shaft 252 is moved to one side in the axial direction, the first stop member 255a compresses the first return spring 254a, and the differential lock fork 253 receiving the elastic force of the first return spring 254a 2. The return spring 254b is moved while being compressed, and the lock member 251 is moved to the lock position.
When the operation force to the differential lock fork shaft 252 is released, the differential lock fork 253 and the differential lock fork shaft 252 are returned to the other side in the axial direction (release direction) by the urging force of the compressed second return spring 254b. Thereby, the lock member 251 is moved to the release position.

  As described above, the differential lock mechanism 250 locks the differential gear device 150 when an operation force is applied to the differential lock fork shaft 252, and the differential gear device 150 is automatically unlocked when the operation force is released. ing.

Further, the traveling system transmission mechanism 50 includes a link mechanism 300 for simultaneously stopping both the pair of drive shafts 180 when the traveling brake device 200 is operated.
That is, as described above, the traveling brake device 200 applies a braking force to the brake shaft 201 disposed on the front stage side of the differential gear device. Therefore, if the brake device 200 is operated without locking the differential gear device 150, there is a risk that a “shift in stop time” may occur between the pair of drive shafts 180 due to a difference in load applied to each of the pair of drive wheels 180. is there. Such “displacement” means that one drive wheel is stopped, but the other drive wheel continues to rotate, and the vehicle slides laterally when stopped. Therefore, when operating the traveling brake device 200, it is necessary to lock the differential gear device 150.

  On the other hand, when one of the pair of driving wheels is idling due to a hollow or the like, the differential gear device 150 needs to be locked in order to transmit sufficient power to the other driving wheel. In such a case, as a matter of course, it is necessary to operate (lock) only the differential lock mechanism 250 without operating the traveling brake device 200.

  The link mechanism 300 is provided to meet such a requirement. When the traveling brake device 200 is operated, the differential lock mechanism 250 is forcibly operated (locked), and only the differential lock mechanism 250 is operated (locked). ).

  Specifically, as shown in FIG. 10, the link mechanism 300 includes a swinging member 302 supported so as to be swingable around the pivot shaft 301 so that the differential lock fork shaft 252 can be moved along the axial direction. A differential lock operating member 303 having a distal end directly or indirectly coupled to the swinging member 302, a distal end locked to the swinging member 302, and a proximal end connected to the connecting arm of the brake device 200. And a long connecting member 304 that moves in the direction of the swinging member 302 in conjunction with the rotation when the connecting arm 216 rotates in a direction in which the traveling brake device 200 is operated. ing.

The swinging member 302 is formed with first and second elongated holes 305 and 306 along the swinging direction of the swinging member 302, and the distal ends of the differential lock operating member 303 and the connecting member 304 are , Are inserted into the first and second elongated holes 305 and 306, respectively.
The first elongated hole 305 has a swinging direction in which the swinging member 302 moves away from the differential lock fork shaft 252 and an end 305a on one side of the swinging direction in which the swinging member 302 pushes the differential lock fork shaft 252. It extends between the other end portion 305b.
Similarly, the second elongated hole 306 also extends between an end 306a on one side of the swinging member 302 in the swing direction and an end 306b on the other side.

As shown in FIG. 10 (a), when both the traveling brake device 200 and the diff lock mechanism 250 are in an inoperative state, the distal ends of the diff lock operation member 303 and the connecting member 304 are respectively The first and second elongated holes 305 and 306 are positioned at one end portions 305a and 306a in the swing direction.
Therefore, when the brake device 200 is operated and the connecting member 304 moves in the direction of the swing member 302, the swing member 302 swings to one side of the swing direction and moves the differential lock fork shaft 252. (See FIG. 10 (b)).

  On the other hand, when only the diff lock mechanism 250 is operated alone, as shown in FIG. 10 (c), the oscillating member 302 is oscillated to one side of the oscillating direction by the diff lock operating member 303. The differential lock fork shaft 252 is moved, but the connecting member 304 is not moved. That is, even when the swing member 302 swings to one side in the swing direction, the connecting member 304 is prevented from moving by the second long hole 306.

  In this way, the link mechanism 300 can allow only the differential lock mechanism 250 to operate while forcibly locking the differential lock mechanism 250 when the traveling system brake device 200 is operated.

In the transmission 30 having such a configuration, the following effects can be obtained in addition to the various effects described above.
That is, the PTO system input shaft 31 and the traveling system input shaft 34 are distributed up and down substantially at the center in the width direction of the transmission case 60, and the PTO system transmission mechanism 40 following the PTO system input shaft 31 is connected to the PTO system input shaft. 31, the traveling system transmission mechanisms 50 that are gathered on the other side in the width direction of the mission case 60 and that follow the traveling system input shaft 34 are arranged on one side in the width direction of the mission case 60 and the traveling system input shaft 34 as a reference. Since the lower and upper widths of the transmission case 60 are effectively compressed, the upper space of the traveling transmission mechanism 50 in the transmission case can be secured as a storage space for other members.
For example, a cylinder tube 401 of a hydraulic lift device 400, which will be described later, can be stored in the storage space for the other members.

  Further, the power transmission from the PTO transmission shaft 41 to the mid PTO shaft 33 is performed by a mid PTO transmission gear train 43 disposed behind the differential gear device 150. Therefore, the tip position (driving force extraction position) of the mid PTO shaft 33 can be brought as close as possible to the pair of axles 180. The fact that the tip position of the mid PTO shaft 33 can be arranged close to the axle 180 in this way increases the distance between the tip portion of the mid PTO shaft 33 and the first working device 112 driven by the mid PTO shaft 33. This means that when the first working device 112 is lifted, a universal joint in the transmission mechanism that connects the first working device 112 and the mid PTO shaft 33 to the mid PTO shaft 33 is obtained. The folding angle can be reduced. Therefore, the first working device 112 can be raised and lowered without difficulty, and effects such as noise reduction and durability improvement can be obtained.

  Further, in the transmission 30, the PTO transmission shaft 41 is displaced to the other side in the width direction of the transmission case 60 as described above. The mid PTO shaft 33 is also displaced to the other side in the width direction of the mission case 60. Therefore, the linear distance between the PTO transmission shaft 41 and the mid PTO shaft 33 can be made closer. The traveling system transmission mechanism 50 is disposed in front of the mission case 60 in the front-rear direction, and the mid PTO transmission gear train 43 that connects the PTO system transmission shaft 41 and the mid PTO shaft 33 is disposed behind the mission case 60. Thus, the mid PTO gear train 43 can be arranged on a virtual straight line connecting the PTO transmission shaft 41 and the mid PTO shaft 33. Such a linear arrangement enables the mid PTO transmission gear train 43 to be reduced and simplified as much as possible.

Further, the transmission 30 includes an idle gear 42b and an intermediate shaft 42c in a rear PTO gear train 42 that transmits power from the PTO transmission shaft 41 to the rear PTO shaft 32, and these members are connected to the PTO system. The transmission shaft 41 is disposed on one side in the vehicle width direction, thereby realizing the deceleration transmission from the PTO transmission shaft 41 to the rear PTO shaft 32 and effectively suppressing the expansion of the transmission case 60. .
That is, generally, it is necessary to transmit the driving force by decelerating from the PTO transmission shaft 41 to the rear PTO shaft 32. If the rear PTO gear member 42a supported by the PTO transmission shaft 41 and the final gear 42e supported by the rear PTO shaft 32 are directly meshed, the pitch circle radius of the rear PTO gear member 42a is increased. As a result, the inter-shaft distance between the PTO transmission shaft 41 and the rear PTO shaft 32 becomes long, and as a result, the transmission case 60 is enlarged.

In view of this point, in the present embodiment, as described above, the idle gear 42b and the intermediate shaft 42c are interposed between the rear PTO gear member 42a and the final gear 42e, and the idle gear 42b and the intermediate shaft 42 42c is disposed on one side of the PTO transmission shaft 41 in the vehicle width direction. That is, as shown in FIG. 7, the PTO transmission shaft 41 is arranged on the other side in the width direction of the transmission case with respect to the position in the width direction of the transmission case 60 with respect to the PTO input shaft 31 and the traveling input shaft 34. In addition, the vertical position is arranged between the input shafts 31 and 34. Here, as described above, the traveling system transmission mechanism 50 is collectively disposed on one side and the lower side in the width direction of the transmission case with the traveling system input shaft 34 as a reference. Accordingly, an empty space exists on one side in the width direction of the PTO transmission shaft 41 at the rear in the front-rear direction of the transmission case 60.
In the transmission 30, the idle gear 42 b and the intermediate shaft 42 c are disposed in the empty space, thereby allowing transmission transmission from the PTO transmission shaft 41 to the rear PTO shaft 32 and transmission case 60. Is effectively prevented from expanding.

  The vehicle 100 according to the present embodiment further controls a hydraulic lift device 400 for raising and lowering a working device such as a tiller disposed behind the chassis 10 and pressure oil supply / discharge control for the hydraulic lift device 400. A valve unit 410; an auxiliary pump 420 for supplying pressure oil to the valve unit 410; and an auxiliary pump transmission mechanism 430 for transmitting a driving force from the PTO system input shaft 31 to the auxiliary pump 420. Yes.

  As shown in FIGS. 3 to 5, the hydraulic lift device 400 is housed in a cylinder tube 401 disposed in the longitudinal direction of the vehicle and in a reciprocating and liquid-tight manner in the cylinder tube 401. A piston head 402; a piston rod 403 having a front end connected to the piston head 402 and a rear end extending rearward from the rear end opening of the cylinder tube 401; and a support supported along the vehicle width direction. A shaft 404, an arm 405 whose base end portion is supported by the support shaft 404 so as not to rotate relative to the shaft 404, and a tip end portion connected to the rear end portion of the piston rod 403, and a base end portion that rotates relative to the support shaft 404. A pair of lift arms 406 that are supported in an impossible manner and whose front ends extend to the rear of the chassis, so that pressure oil acts on the piston head 402. By, so that the can is rocked the pair of lift arms 406 around the axis of the support shaft 404.

Here, the installation positions of the cylinder tube 401, the valve unit 410, and the auxiliary pump 420 will be examined.
First, considering the vertical position of the cylinder tube 401, the cylinder tube 401 is disposed above the PTO input shaft 31 (or the pump shaft 21a), whereby the PTO transmission mechanism 40 is arranged. To prevent interference. The cylinder tube 401 is disposed above the PTO input shaft 31 in the case where the cylinder tube 401 is disposed at an upper position in the mission case 60 and on the upper surface of the mission case 60. The case where it is set is included.

  Next, regarding the position of the cylinder tube 401 in the vehicle width direction, the cylinder tube 401 is disposed on one side of the transmission case 60 in the vehicle width direction. The front opening of the cylinder tube 401 is closed by the valve unit 410. That is, the cylinder tube 401 and the valve unit 410 are connected along the longitudinal direction of the vehicle on one side in the vehicle width direction of the transmission case 60.

  On the other hand, the auxiliary pump 420 is supported by the transmission case 60 so as to be positioned on the other side in the vehicle width direction of the valve unit 410 and the cylinder tube 401.

  Thus, in the present embodiment, the valve unit 410 and the cylinder tube 401 are disposed on one side in the vehicle width direction of the transmission case 60, and the auxiliary pump 420 is disposed on the other side in the vehicle width direction of the transmission case 60. Accordingly, the following effects are obtained.

  That is, in the conventional working vehicle, the valve unit and the cylinder tube are arranged on the upper surface of the transmission case along the longitudinal direction of the vehicle, and the auxiliary pump for supplying pressure oil to the valve unit is the transmission case. It was supported by the rear wall. Therefore, when the stored oil in the mission case is supplied to the cylinder tube, the stored oil is once routed from the lower side of the mission case to the rear of the mission case, and then supplied to the cylinder tube via the valve unit on the upper surface of the mission case. There is a problem that the oil distribution route becomes long. Such an increase in the length of the oil distribution path includes an increase in the size of the hydraulic pump due to pressure loss, an increase in the size of the vehicle due to an increase in piping space, and a decrease in the reaction speed of the hydraulic device due to a decrease in the pressure oil supply speed to the hydraulic device. Invite.

  On the other hand, in the present embodiment, as described above, the valve unit 410 and the cylinder tube 401 are continuously provided along the longitudinal direction of the vehicle on one side in the vehicle width direction of the transmission case 60, and the valve unit 410 and the cylinder are connected. The auxiliary pump 420 is disposed on the other side of the tube 401 in the vehicle width direction. Therefore, the oil flow path for supplying the hydraulic oil from the mission case 60 to the valve unit 410 via the auxiliary pump 420 can be shortened, thereby reducing the size of the auxiliary pump 420, the size of the vehicle, and the hydraulic device. The reaction rate can be increased.

  Preferably, in the transmission case 60, a stored oil outlet 65 (see FIGS. 2 and 3) is provided at substantially the same position in the vehicle longitudinal direction as the auxiliary pump 420, and the intake of the stored oil outlet 65 and the auxiliary pump 420 is provided. The port can be fluidly connected, whereby the oil circulation path can be further shortened.

  FIG. 11 is a sectional view taken along line XI-XI in FIG. As shown in FIGS. 3 and 11, it is more preferable that a strainer 66 is provided in the mission case 60 and the stored oil can be taken out from the stored oil outlet 65 via the strainer 66. Thereby, the impurities of iron powder can be effectively removed.

  In the present embodiment, as shown in FIGS. 3 to 5, a first bulging portion 61 a bulging upward on one side in the vehicle width direction is integrally formed with the main body portion 61 of the mission case 60. The cylinder tube 401 is disposed in the first bulging portion 61a, whereby the installation position of the cylinder tube 401 is lowered to reduce the vehicle height.

  That is, when the cylinder tube is installed on the upper surface of the transmission case, a member for supporting the cylinder tube is separately required, and the installation position of the cylinder tube is increased. Therefore, the manufacturing cost is increased due to an increase in the number of parts, and the vehicle height is increased. In general, the driver's seat is often disposed above the cylinder tube (see FIG. 1). Therefore, when the cylinder tube is installed at a higher position, the driver's seat is installed at a higher position. It will cause difficulty in climbing and getting on and off the driver's seat.

  On the other hand, in the present embodiment, the cylinder tube 401 is accommodated in the first bulging portion 61a of the transmission case 60. Therefore, the installation position of the cylinder tube 401 is lowered and the cylinder tube 401 is mounted. It can be supported stably.

Further, by accommodating the cylinder tube 401 in the transmission case 60, the support shaft 404 can be supported by the transmission case 60 without requiring a special mechanism, thereby reducing the manufacturing cost. Thus, the support shaft 404 can be stably held.
In the present embodiment, as clearly shown in FIG. 4, the support shaft 404 is connected to the mission case 60 so that both end portions of the support shaft 404 extend outward from both side walls of the mission case 60. Each of the pair of lift arms 406 is connected to the extending portions at both ends.

  As shown in FIG. 6, the auxiliary pump transmission mechanism 430 includes a drive side gear 431 a that is supported by the PTO system input shaft 31 so as not to be relatively rotatable, an idle gear 431 b that meshes with the drive side gear 431 a, A gear train 431 including a driven gear 431c supported so as not to rotate relative to the pump shaft 421 of the auxiliary pump 420 so as to mesh with the idle gear 431b is provided.

  As shown in FIG. 6, the gear train 431 is disposed above the right side portion of the PTO system input shaft 31 in the front view, and thereby disposed below the right side portion of the PTO system input shaft 31. The space in the transmission case is effectively used while preventing interference with the PTO transmission mechanism 40 including the PTO transmission shaft 41 and the traveling transmission mechanism 50 disposed on the left side of the traveling input shaft 34. ing.

  That is, in the present embodiment, the PTO system input shaft 31 and the traveling system input shaft 34 are juxtaposed in the vertical direction at the center portion in the vehicle width direction of the transmission case, and the auxiliary pump driven by the PTO system input shaft 31. The transmission mechanism 430 and the PTO transmission mechanism 40 are arranged separately in the vertical direction on one side in the vehicle width direction, and the traveling system transmission mechanism 50 driven by the traveling system input shaft 34 is disposed on the other side in the vehicle width direction of the transmission case. It is arranged in a concentrated manner at the lower side, thereby making effective use of space while preventing mutual interference between the transmission mechanisms.

Preferably, as shown in FIGS. 4 and 6, in the main body portion 61 of the mission case 60, the front lid portion bulges upward at a position opposite to the first bulging portion 61a in the vehicle width direction. The second bulging part 61b closed by 62 can be provided, and the auxiliary pump 420 can be supported by the second bulging part 61b, thereby stabilizing the auxiliary pump 420 and reducing the number of parts. Cost reduction can be achieved.
More preferably, a part of the gear train 431 can be accommodated in the closed space defined by the second bulging portion 61 b and the front lid portion 62.

  In the present embodiment, an opening communicating with the closed space defined by the front lid portion 62 and the second bulging portion 61b is formed in the second bulging portion 61b, and the opening is communicated through the opening. Although the pump shaft 421 is inserted into the closed space from the rear to be connected to the driven gear 431c so as not to be relatively rotatable, the present invention is not limited to such a form. That is, as shown in FIG. 16, an opening communicating with the closed space may be provided in the front lid portion 62, and the pump shaft 421 may be plunged from the front. Further, when the auxiliary pump 420 described later is a tandem dual type, as shown in FIG. 17, the pump shafts 421 ′ and 421 ″ are inserted from both the front and rear surfaces of the bulging portion 61b, respectively, so that the dual pump 420 'and 420' 'can be distributed forward and backward, respectively, or the dual pumps 420' and 420 '' can be provided in front of or behind the bulging portion.

Next, a hydraulic circuit having a transmission structure according to the present embodiment will be described.
12 is a hydraulic circuit diagram of the hydraulic lift device 400 and the valve unit 410, and FIG. 13 is a hydraulic circuit diagram of the center section and the PTO clutch device. FIG. 14 is a longitudinal front view of the center section.

The stored oil outlet 65 of the mission case 60 is connected to a suction port 420a of an auxiliary pump 420 installed on the upper side of the mission case 60 via a pipe 501 (see FIG. 2). That is, the stored oil in the mission case 60 is filtered by the strainer 66 disposed in the mission case 60, and then sucked into the suction port 420 a of the auxiliary pump 420 through the stored oil take-out port 65 and the pipe 501. It is.
Then, the pressure oil discharged from the discharge port 420b of the auxiliary pump 420 is supplied to the valve unit 410 arranged in parallel with the auxiliary pump 420 along the vehicle width direction via the pipe 502 (see FIG. 2). .

  The valve unit 410 has a proximal end side opened to the upper surface of the valve unit 410 and a distal end side branched into first and second lines 412 and 413 via a flow dividing valve built in the valve unit 410. 411 is formed.

  In the present embodiment, an auxiliary control valve unit 450 is connected to the side surface of the valve unit 410 so that the supply direction of the pressure oil flowing through the first line 412 can be appropriately set. That is, by providing the auxiliary control valve unit 450, the pressure oil flowing through the first line 412 can be used for a hydraulic device that drives the bucket device 111 (see FIG. 1) up and down and dumps / tilts.

  As shown in FIGS. 4 and 12, the auxiliary control valve unit 450 includes a unit main body 451, a plurality of hydraulic lines 452 formed in the main body 451, and one inserted in the plurality of hydraulic lines 452. Alternatively, a plurality of (two in the present embodiment) switching valves 453 are provided so that the pressure oil introduced from one hydraulic line can be taken out from a plurality of outlets.

  The distal end side of the first line 412 opens to the side surface of the valve unit via a high pressure relief valve 414 that sets the hydraulic pressure of the first line 412, and communicates with one hydraulic line of the auxiliary control valve unit 450. ing.

  As described above, the valve unit 410 can block the front opening of the cylinder tube 401. That is, the valve unit 410 has a closing projection 410a that is liquid-tightly inserted into the front opening of the cylinder tube 401 on the rear end surface, and constitutes a cylinder head.

Further, the valve unit 410 has a proximal end side that opens to the side surface thereof and communicates with one hydraulic line of the auxiliary control valve unit 450, and a distal end side that extends from the rear end surface of the closing projection 410a to the cylinder tube 401. A working oil line 415 (see FIGS. 4 and 12) is provided in the interior.
An elevation switching valve 416 and a stop valve 417 that are both externally operable are inserted in the hydraulic oil line 415. The stop valve 417 is provided with a slow return valve 418 for preventing the lift arm 406 from dropping rapidly.

Reference numeral 416a in FIGS. 4 and 5 is a link mechanism for operating the up / down switching valve 416, and the up / down switching valve 416 is moved to any one of the three positions "up", "neutral", and "down". It is connected to an elevating operation lever 416b for switching. The lift control lever 416b feeds back the movement of the lift arm 406. The lift switching valve 416 is switched from the neutral position to the lift (or drop) position, and the tip of the lift arm 406 rises to a predetermined lift (or When the height reaches (down), the movement of the lift arm 406 is fed back to forcibly return the lifting operation lever 416b to the neutral position.
4, 5, and 12 is a drain line for returning drain oil flowing out through the elevation switching valve 416 into the mission case 60.

  On the other hand, the distal end side of the second line 413 is open on the upper surface of the valve unit 410, and is optionally provided via a pipe 503 for a hydraulic circuit 500 for a power steering device and the PTO clutch device 70. And a hydraulic circuit 600 (see FIGS. 12 and 13).

  In the present embodiment, the oil discharged from the single auxiliary pump 420 is divided into the first and second lines 412 and 413 using the flow dividing valve. However, the oil accompanying the operation of the flow dividing valve is used. When the temperature rise becomes a problem, instead of using the flow dividing valve, the auxiliary pump 420 is replaced with a tandem dual pump 420 ′, 420 ″ as shown in FIG. 18, and the discharge of one pump 420 ′ is performed. The port can be connected to the first line 412 and can be connected to the discharge port second line 413 of the other pump 420 ″, thereby eliminating the above-mentioned problems.

  As shown in FIG. 13, the PTO clutch device hydraulic circuit 600 includes a suction line 601 whose base end is communicated with the distal end side of the second line 413 directly or via the power steering device hydraulic circuit 500; A PTO line 602 and an HST line 603 branched from the suction line 601, a switching valve 604 inserted in the PTO line 602, and a high-pressure relief valve 605 inserted in the HST line 603 are provided.

In the present embodiment, as shown in FIG. 5, the PTO clutch device hydraulic circuit 600 is formed in the side cover portion 64 of the mission case 60.
The PTO line 602 is connected to the clutch pushing member 75 of the PTO clutch device 70 and the PTO brake mechanism 80 via a clutch line 611 and a brake line 612 formed in the main body 61 of the transmission case 60, respectively. It can act on the brake pushing member 83 (refer FIG.5 and FIG.9).
Reference numeral 609 in FIGS. 5 and 9 is a drain line for returning drain oil flowing out through the switching valve 604 into the mission case 60.

  The front end side of the HST line 603 is connected to a line filter 68 (see FIGS. 2 and 3) and a pipe 504 (see FIGS. 6 and 13) supported on the lower outer surface of the front lid portion 62 of the mission case 60. , Communicated with the center section 23.

FIG. 15 is a partial longitudinal front view of the front lid portion 62 of the mission case 60.
As shown in FIG. 15, the transmission case front lid 62 has a filter suction line 62a having a proximal end side connected to the HST line 603 via a pipe and a distal end side connected to the suction port 68a of the line filter 68. And a filter discharge line 62b having a proximal end side communicated with the discharge port 68b of the line filter 68 and a distal end side communicated with the center section 23.

  As described above, in the present embodiment, hydraulic oil is supplied to the HST line 603 via the strainer 66 disposed in the mission case 60, so the line filter 68 can be reduced in size. it can. That is, when iron powder or the like is included in the HST line 603, a failure of the subsequent HST 20 or the like is caused, so that it is usually necessary to provide a high-performance large line filter. However, in the present embodiment, since the hydraulic oil is filtered to some extent by the strainer 66 as described above, it is not necessary to provide a large filter with such high performance as the line filter 68.

As shown in FIGS. 13 and 14, the center section 23 includes a pair of hydraulic lines 23a and 23a ′ for hydraulically connecting the hydraulic pump 21 and the hydraulic motor 22 of the HST 20, and the pair of hydraulic lines 23a. A first and second bypass lines 23b, 23c connecting the first and second bypass lines 23b, 23c, a charge line 23d having a proximal end communicating with the filter discharge line 62b and a distal end communicating with the first bypass line 23b, and the first bypass line 23b, a check valve 23e inserted between a connection point with one hydraulic line 23a and a connection point with the charge line 23d, and the other hydraulic line 23a 'of the first bypass line 23b A check valve 23f with a throttle valve interposed between the connection point of the second line and the connection point of the charge line 23d, A pair of high-pressure relief valves with check valve 23g inserted in the sline 23c, a charge relief valve 23h inserted in the charge line 23d, a proximal end side opening in the HST casing 24, and a distal end side in the charge line The suction line connected to the rear side of the charge relief valve 23h in 23d, the suction check valve 23j inserted in the suction line 23i, and the relief oil from the charge relief valve 23h are discharged into the HST casing 24. And a discharge line 23k for the purpose.
Reference numeral 231 in FIG. 14 is a drain hole for communicating the inside of the HST casing 24 and the inside of the mission casing 60, and is provided for returning the overflow oil in the HST casing 24 into the mission casing 60.

  The suction line 23i and the suction valve 23j prevent a negative pressure from being generated in the pair of hydraulic lines 23a and 23a when the vehicle is stopped on the slope with the engine stopped. This is to prevent rolling down (free wheel phenomenon).

  In addition, the code | symbol 62c in FIG. 15 is an oil path which connects the said suction line 23i and the inside of the mission case 60. As shown in FIG.

  As described above, the transmission structure according to the present embodiment is configured to supply the pressure oil from the auxiliary pump 420 to the hydraulic lift device 400, the power steering device, the HST 20, the PTO brake mechanism 80, and the PTO clutch device 70. However, an additional pump is not required, and the vehicle size is reduced and the vehicle cost is reduced by reducing the number of parts.

FIG. 1 is a schematic side view of a vehicle to which a preferred embodiment of a transmission structure according to the present invention is applied. FIG. 2 is a partially exploded perspective view of the HST and the transmission portion in the preferred embodiment of the transmission structure according to the present invention. 3 is a longitudinal side view of the HST and transmission shown in FIG. 4 is a partial cross-sectional plan view of the HST and transmission shown in FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a front view of the transmission with the front lid portion removed. FIG. 7 is a rear view of the transmission with a front lid portion removed. FIG. 8 is an exploded view of the transmission drive train along the line VIII-VIII in FIG. FIG. 9 is an exploded view of the transmission PTO system drive train along the line IX-IX in FIG. FIG. 10 is a partial cross-sectional plan view in the vicinity of the brake shaft in the transmission. FIG. 10 (a) shows the non-actuated state of both the traveling brake device and the differential lock device. FIG. 10B shows a state in which the differential lock device is interlocked when the traveling brake device is operated. FIG. 10 (c) shows a state where only the differential lock device is operated alone. 11 is a cross-sectional view taken along line XI-XI in FIG. FIG. 12 is a hydraulic circuit diagram of the hydraulic lift device and the valve unit portion. FIG. 13 is a hydraulic circuit diagram of the center section and the PTO clutch device part. FIG. 14 is a longitudinal front view of the center section. FIG. 15 is a partial longitudinal front view of the front wall portion of the mission case. FIG. 16 is a partial cross-sectional plan view of a variation of the transmission. FIG. 17 is a partial cross-sectional plan view of a modified transmission having a dual pump. FIG. 18 is a hydraulic circuit diagram of the hydraulic lift device and the valve unit when the double pump is provided.

Explanation of symbols

10 Engine 20 HST
21a pump shaft
22a motor shaft 30 transmission
31 PTO input shaft
34 traveling system input shaft
40 PTO transmission mechanism
41 PTO transmission shaft
50 traveling system transmission mechanism
51 transmission shaft (traveling system transmission shaft)
60 Mission case 65 Oil storage outlet 68 Line filter
70 PTO Clutch Device 410 Valve Unit 420 Auxiliary Pump
430 auxiliary pump transmission mechanism

Claims (3)

A transmission for a working vehicle that branches and transmits a driving force from a driving source to a working device and a driving wheel,
A mission case spaced from the drive source in the longitudinal direction of the vehicle;
An HST coupled to the front surface of the transmission case such that the pump shaft and the motor shaft are arranged vertically along the longitudinal direction of the vehicle and substantially at the center in the vehicle width direction of the transmission case;
A PTO system input shaft supported by the transmission case at substantially the center in the vehicle width direction so as to be connected to the pump shaft coaxially with the pump shaft;
A traveling system input shaft supported by the transmission case at a substantially center in a vehicle width direction and coaxially with the motor shaft and below the PTO system input shaft so as to be coupled to the motor shaft;
A traveling system transmission mechanism including a traveling system transmission shaft following the traveling system input shaft;
A PTO transmission mechanism including a PTO transmission shaft following the PTO input shaft;
A PTO clutch device for turning on / off power transmission from the PTO system input shaft to the PTO system transmission shaft;
A valve unit that controls pressure oil supply / discharge control for the hydraulic device for operating the working device;
An auxiliary pump for supplying pressure oil to the valve unit;
The traveling system transmission mechanism is concentrated on one side and the lower side of the transmission case in the vehicle width direction, and the PTO transmission mechanism is integrated on the other side of the transmission case in the vehicle width direction,
The valve unit is supported on one side upper side in the vehicle width direction at the front portion of the transmission case,
The auxiliary pump is supported on the other side in the vehicle width direction at the front portion of the transmission case, and overlaps the valve unit with respect to the vehicle longitudinal direction position,
From the front side of the PTO clutch device of the PTO input shaft through an auxiliary pump Den motive structure disposed above the and the PTO transmission mechanism in the width direction of the vehicle the other side of the transmission case to the auxiliary pump A transmission for a working vehicle characterized by transmitting rotational power. The mission case is provided with a stored oil outlet at the front for taking out the oil stored inside ,
Working vehicle transmission as claimed in claim 1 before Symbol auxiliary pump, characterized in that it is fluidly connected to the takeout said stored fluid through the external pipe. Further comprising a interpolated line filter over through between the before and Symbol auxiliary pump HST,
Takeout prior Symbol oil reservoir is disposed below the transmission case,
The work vehicle transmission according to claim 1, wherein the line filter is supported on a front surface of the mission case at a position below the HST.

Images