JP6994239B2 - Work vehicle - Google Patents

Description

The present invention relates to a work vehicle having a hydrostatic / mechanical continuously variable transmission mechanism (HST) and a hydrostatic / mechanical continuously variable transmission structure (HMT structure) having a planetary gear mechanism.

The HMT structure, which is a combination of the HST and the planetary gear mechanism, is used for a traveling system transmission path of a work vehicle such as a combine harvester or a tractor.

For example, in Patent Document 1 below, the output rotational power of the planetary gear mechanism is set to zero speed by shifting the HST to the set intermediate speed between the maximum speed on the reverse side and the neutral speed, and the HST is set from the set intermediate speed. The output rotational power of the planetary gear mechanism is increased to the reverse side as the speed is changed to the maximum speed on the reverse rotation side, and the planetary gear is changed from the set intermediate speed to the maximum speed on the normal rotation side via the neutral speed. A combine in which an HMT structure configured to increase the output of the mechanism to the forward side is inserted in a traveling system transmission path is disclosed.

The combine described in Patent Document 1 is useful in that it can travel in both forward and backward directions by the speed change operation of the HST without separately providing a forward / backward switching mechanism.

Japanese Patent No. 5822761

However, the conventional combine has a problem that it is difficult to bring out a running stop state by setting the output of the HMT structure to a zero speed state (the output rotational power of the planetary gear mechanism is a zero speed state). rice field.

That is, in order to set the output of the HMT structure to the zero speed state in the conventional combine, the shift operation lever for shifting the HST is positioned at the set intermediate speed position corresponding to the set intermediate speed of the HST. It is necessary to manufacture the HST and the link mechanism of the HST and the speed change operation lever so that the output rotational power of the HST becomes the set intermediate speed accurately, and further, the set intermediate speed is set from the HST. It is necessary to strictly manufacture and assemble the HST and the planetary gear mechanism so that the output rotational power of the planetary gear mechanism becomes zero speed when the output rotational power of the above is input.

Further, in a work vehicle in which a traveling member is operatively rotationally driven by the output rotational power of the HMT structure as in the conventional combine, it is difficult to pull the work vehicle in the event of a failure or the like. There was also.

That is, when the work vehicle provided with the HMT structure is towed, the hydraulic motor of the HST operated and connected to the traveling member is forcibly rotated by the rotation of the traveling member. Here, the HST hydraulic pump to which the hydraulic motor is fluidly connected via a pair of hydraulic oil lines is operatively connected to a drive source such as an engine and is in a state where it cannot rotate freely.

Therefore, when the hydraulic motor is forcibly rotated with the rotation of the traveling member when the work vehicle is towed, the pair of hydraulic pumps cannot rotate due to the operational connection with the drive source. The oil discharged from the hydraulic motor will flow into one of the hydraulic oil lines, and the hydraulic pressure of the one hydraulic oil line will hinder the rotation of the hydraulic motor.

The present invention has been made in view of the above-mentioned prior art, and is a work vehicle in which a traveling member is operatively rotationally driven by an output rotational power of an HMT structure including an HST and a planetary gear mechanism, and is an output of the HMT structure. It is an object of the present invention to provide a work vehicle capable of rotationally driving the traveling member in both forward and backward directions, and further preventing the work vehicle from unexpectedly moving at a creep speed.

Further, the present invention is a work vehicle in which a traveling member is operatively rotationally driven by an output rotational power of an HMT structure including an HST and a planetary gear mechanism, and the traveling member is driven forward and backward by the output of the HMT structure. It is an object of the present invention to provide a work vehicle that can be rotationally driven and can be easily towed in the event of a failure or the like.

In the first aspect of the present invention, in order to achieve the above object, a drive source, an HST that continuously shifts and outputs a rotational power input from the drive source, a rotational power from the drive source, and the HST. The planetary gear mechanism that inputs the rotational power from the first and second elements to the first and second elements, synthesizes the rotational powers of the first and second elements, and outputs them from the third element, and the rotation output from the planetary gear mechanism. A work vehicle provided with a traveling member operably driven by power and a shift operation lever for shifting the HST, and a brake capable of selectively applying a braking force to the third element of the planetary gear mechanism. A mechanism and a bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST are provided, and the shift operation lever moves in the first operation direction toward the forward side and the reverse side across the zero speed position. In addition to the gear shifting operation along, it is possible to operate from the zero speed position to the brake position along the second operation direction different from the first operation direction and from the brake position to the bypass position along the first operation direction. In the HST and the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the shift operation lever advances from the zero speed position. The rotational power output from the planetary gear mechanism is configured to be accelerated to the forward side and the reverse side as they are operated to the side and the reverse side, respectively, and the shift operation lever is the first operation. When the gear shift operation is performed along the direction, the brake mechanism releases the braking force to the third element , and the bypass mechanism cuts off between the pair of hydraulic oil lines to perform the gear shift operation. When the lever is operated to the brake position, the brake mechanism applies a braking force to the third element, the bypass mechanism communicates between the pair of hydraulic oil lines, and the shift operation lever is in the bypass position. When operated to, the work vehicle is configured to release the braking force of the brake mechanism on the third element while maintaining the communication between the pair of hydraulic oil lines by the bypass mechanism. I will provide a.

Further, in the second aspect of the present invention, the drive source, the HST that continuously shifts and outputs the rotational power input from the drive source, and the rotational power from the drive source and the rotational power from the HST, respectively. It is driven operatively by a planetary gear mechanism that inputs to the first and second elements, synthesizes the rotational powers of the first and second elements, and outputs them from the third element, and the rotational power output from the planetary gear mechanism. A working vehicle including a traveling member to be geared and a gear shifting operating lever for shifting the HST, the brake mechanism capable of selectively applying a braking force to the third element of the planetary gear mechanism, and the HST. It is equipped with a bypass mechanism that can switch between shutoff and communication between a pair of hydraulic oil lines, and the shift operation lever is provided with a shift operation along the first operation direction to the forward side and the reverse side across the zero speed position. The operation from the zero speed position to the brake position along the second operation direction different from the first operation direction and the operation from the zero speed position to the bypass position opposite to the brake position along the second operation direction. In the HST and the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the shift operation lever is zero. As the operation is performed from the speed position to the forward side and the reverse side, the rotational power output from the planetary gear mechanism is configured to be accelerated to the forward side and the reverse side, respectively, and the brake mechanism is the said. When the shift operation lever is operated to shift gears along the first operation direction, the braking force on the third element is released, and when the shift operation lever is operated to the brake position, the third element is released. It is configured to apply a braking force, and when the gear shifting operating lever is geared along the first operating direction, the braking mechanism releases the braking force to the third element and The bypass mechanism shuts off between the pair of hydraulic oil lines, and when the gear shifting operating lever is operated to the brake position, the brake mechanism applies a braking force to the third element, and the bypass mechanism When the gear shifting operating lever is operated to the bypass position by communicating between the pair of hydraulic oil lines, the brake mechanism releases the braking force to the third element, and the bypass mechanism is the pair. Provide a work vehicle that communicates between hydraulic oil lines .

Further, in the third aspect of the present invention, the drive source, the HST that continuously shifts and outputs the rotational power input from the drive source, and the rotational power from the drive source and the rotational power from the HST, respectively. It is driven operatively by a planetary gear mechanism that inputs to the first and second elements, synthesizes the rotational powers of the first and second elements, and outputs them from the third element, and the rotational power output from the planetary gear mechanism. A work vehicle including a traveling member to be geared and a gear shifting operating lever for shifting the HST, a bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST, and the planetary gear. The third element of the mechanism is provided with a brake mechanism that selectively applies a braking force, and the shift operation lever is provided with a shift operation along the first operation direction to the forward side and the reverse side across the zero speed position. , The operation from the zero speed position to the bypass position along the second operation direction different from the first operation direction and the operation from the bypass position to the brake position in the direction different from the zero speed position are possible, and the HST and In the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the speed change operation lever is operated from the zero speed position to the forward side and the reverse side. As a result, the rotational power output from the planetary gear mechanism is configured to be accelerated to the forward side and the reverse side, respectively, and the speed change operation lever is changed and operated along the first operation direction. When so, the bypass mechanism shuts off between the pair of hydraulic oil lines, the brake mechanism releases the braking force on the third element, and the gear shifting operating lever is operated to the bypass position. Then, when the bypass mechanism communicates between the pair of hydraulic oil lines, the brake mechanism releases the braking force to the third element, and the gear shifting operating lever is positioned at the brake position. Provided is a working vehicle in which the braking mechanism is configured to apply braking force to the third element while maintaining communication between the pair of hydraulic oil lines by the bypass mechanism .

In the work vehicle according to the various configurations, preferably, the speed change operation lever has a first operation shaft supported so as to be rotatable around an axis and a second operation supported in a state orthogonal to the first operation shaft. It is assumed to have a shaft, a lever body that is artificially operated, and a connecting member that connects the base end portion of the lever body to the second operating shaft, and the lever body, the connecting member, the second operating shaft, and the like. By integrally rotating the first operating shaft around the axis of the first operating shaft, a speed change operation is performed along the first operating direction, while the lever body and the connecting member are the first. The operation is configured to be performed along the second operation direction by being rotated around the axis of the two operation shafts.

According to the working vehicle according to the first aspect of the present invention, a barrier mechanism capable of selectively applying a braking force to a third element which is an output element of the planetary gear mechanism and a cutoff between a pair of hydraulic oil lines in the HST. And a bypass mechanism that can switch communication is provided, and the shift operation lever moves forward and backward across the zero speed position in addition to the shift operation along the first operation direction, from the zero speed position to the first operation direction. It is possible to operate to the brake position along the second operation direction different from that of the above, and to operate from the brake position to the bypass position along the first operation direction, and the HMT structure formed by the HST and the planetary gear mechanism is When the shift control lever is positioned at the zero speed position, the output becomes zero speed, and the output increases to the forward side and the reverse speed as the shift control lever is operated from the zero speed position to the forward side and the reverse side, respectively. When the gear shifting operation lever is gear-shifted along the first operating direction, the braking mechanism releases the braking force , and the bypass mechanism is the pair of hydraulic oil lines. When the shift operation lever is operated to the brake position, the brake mechanism applies a braking force , and the bypass mechanism communicates between the pair of hydraulic oil lines to perform the shift operation. When the lever is operated to the bypass position, the work vehicle is configured to release the braking force while the communication between the pair of hydraulic oil lines by the bypass mechanism is maintained. Can be reliably prevented from moving at creep speed against the driver's will.

According to the working vehicle according to the second aspect of the present invention, a brake mechanism capable of selectively applying a braking force to a third element which is an output element of the planetary gear mechanism and a cutoff between a pair of hydraulic oil lines in the HST. A brake mechanism that is equipped with a bypass mechanism that can switch between communication and a brake mechanism that can selectively apply braking force to the third element, which is the output element of the planetary gear mechanism, and a cutoff between a pair of hydraulic oil lines in the HST and It is equipped with a bypass mechanism that can switch the communication, and the shift operation lever moves from the zero speed position to the first operation direction in addition to the shift operation along the first operation direction to the forward side and the reverse side across the zero speed position. Is capable of operating to the brake position along a different second operating direction and from the zero speed position to the bypass position on the opposite side of the braking position along the second operating direction, HST and planetary gear mechanisms. In the HMT structure formed by, the output becomes zero speed when the speed change operation lever is positioned at the zero speed position, and the output advances as the speed change operation lever is operated from the zero speed position to the forward side and the reverse side, respectively. The speed is increased to the side and the reverse side, and when the speed change operation lever is changed speed along the first operation direction, the brake mechanism releases the braking force and the bypass is used. The mechanism shuts off between the pair of hydraulic oil lines, and when the gear shifting operating lever is operated to the brake position, the brake mechanism applies a braking force, and the bypass mechanism is of the pair of hydraulic oil lines. When the shift operation lever is operated to the bypass position, the brake mechanism releases the braking force, and the bypass mechanism is configured to communicate between the pair of hydraulic oil lines. Therefore, it is possible to reliably prevent the working vehicle from moving at a creep speed against the will of the operator.

According to the work vehicle according to the third aspect of the present invention, a bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST and a braking force selectively applied to the third element of the planetary gear mechanism. In addition to the gear shifting operation along the first operating direction from the zero speed position to the forward side and the reverse side with the gear shifting operating lever sandwiching the zero speed position, a second operation direction different from the first operating direction is provided. It is possible to operate to the bypass position along the operation direction and to the brake position in a direction different from the zero speed position from the bypass position , and the HMT structure formed by the HST and the planetary gear mechanism has the speed change operation lever. Is positioned at the zero speed position, the output becomes zero speed, and the output is configured to increase to the forward side and the reverse side as the speed change operation lever is operated from the zero speed position to the forward side and the reverse side, respectively. When the gear shifting operation lever is geared along the first operating direction, the bypass mechanism cuts off between the pair of hydraulic oil lines , and the braking mechanism exerts a braking force. When the gear is released and the shift operation lever is operated to the bypass position, the bypass mechanism communicates between the pair of hydraulic oil lines , and the brake mechanism releases the braking force to the third element. When the shift control lever is positioned at the brake position, the brake mechanism is configured to apply braking force while maintaining communication between the pair of hydraulic oil lines by the bypass mechanism. By setting the planetary gear mechanism, which is actuated and connected to the traveling member of the work vehicle, into a rotatable free state, the forced towable state of the work vehicle can be easily expressed.

FIG. 1 is a transmission schematic diagram of a work vehicle according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the HMT structure provided in the work vehicle shown in FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. FIG. 4 is a hydraulic circuit diagram of the work vehicle. 5 (a) and 5 (b) are a front view and a side view of a speed change operation lever provided in the work vehicle, respectively. FIG. 6 is a plan view of the shift operation lever. FIG. 7 is a plan view of a speed change operation lever provided in the work vehicle according to the first modification of the embodiment. FIG. 8 is a plan view of a speed change operation lever provided in the work vehicle according to the second modification of the embodiment. FIG. 9 is a plan view of a speed change operation lever provided in a work vehicle according to another embodiment of the present invention. FIG. 10 is a partial cross-sectional view of an HMT structure provided with a modification of the brake mechanism according to the embodiment. FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. FIG. 12 is a partial cross-sectional view of the HMT structure provided with another modification of the brake mechanism according to the embodiment. FIG. 13 is a cross-sectional view taken along the line XIII-XIII in FIG.

Embodiment 1
Hereinafter, an embodiment of the work vehicle according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a transmission schematic diagram of the work vehicle 1 according to the present embodiment.

As shown in FIG. 1, the work vehicle 1 according to the present embodiment has a drive source 5 and an HST (hydrostatic continuously variable transmission) that continuously shifts and outputs the rotational power input from the drive source 5. Mechanism) 10, a planetary gear mechanism 100 that cooperates with the HST 10 to form an HMT structure (structural hydrostatic / mechanical continuously variable transmission structure) 200, and a rotational power output from the planetary gear mechanism 100. It is provided with a traveling member 6 driven by the vehicle.

FIG. 2 shows a cross-sectional view of the HMT structure 200.
Further, FIG. 3 shows a cross-sectional view taken along the line III-III in FIG.
Further, FIG. 4 shows a hydraulic circuit diagram of the work vehicle 1.

As shown in FIGS. 1, 2 and 4, the HST 10 includes a pump shaft 20 operatively driven by the drive source 5 and a hydraulic pump 25 supported by the pump shaft 20 so as to be relatively non-rotatable. A hydraulic motor 35 that is fluidly connected to the hydraulic pump 25 via a pair of hydraulic oil lines 601 and 602 and is hydraulically driven to rotate by the hydraulic pump 25, and a motor that non-rotatably supports the hydraulic motor 35. By changing the volumes of at least one of the shaft 30, the hydraulic pump 25, and the hydraulic motor 35, the rotation of the HST output output from the motor shaft 30 with respect to the rotation speed of the rotational power input to the pump shaft 20. It has an output adjusting member 40 that continuously changes the ratio of the speed (that is, the gear ratio of the HST 10).

The output adjusting member 40 causes the HST output output from the motor shaft 30 to be within a shifting range in both forward and reverse directions in response to an artificial operation on the shifting operation lever 700A provided on the working vehicle 1 so as to be artificially operable. It is configured to shift continuously at.

In the present embodiment, the HST 10 is a movable swash plate that changes the volume of the hydraulic pump 25 by swinging around a swing axis as the output adjusting member 40, and is from the hydraulic pump 25. It has a movable swash plate that can swing to one side and the other side around the swing axis with a neutral position where the discharge amount to be discharged is zero.

When the movable swash plate is positioned in the neutral position, the pressure oil is not discharged from the hydraulic pump 25, and the hydraulic motor 35 is in the zero output speed state.
Then, when the movable swash plate is swung from the neutral position to the normal rotation side on one side around the swing shaft, the corresponding hydraulic oil line among the pair of hydraulic oil lines 601 and 602 from the hydraulic pump 25 ( For example, hydraulic oil is supplied to the hydraulic oil line 601), the corresponding hydraulic oil line 601 is on the high pressure side, and the other working line 602 is on the low pressure side.
As a result, the hydraulic motor 35 is rotationally driven to the forward rotation side.

On the contrary, when the movable swash plate is swung from the neutral position to the reversing side on the other side around the swing axis, the corresponding hydraulic oil line among the pair of hydraulic oil lines 601 and 602 from the hydraulic pump 25 ( For example, hydraulic oil is supplied to the hydraulic oil line 602), the corresponding hydraulic oil line 602 is on the high pressure side, and the other hydraulic oil line 601 is on the low pressure side.
As a result, the hydraulic motor 35 is rotationally driven to the reverse side.

In the HST 10, the volume of the hydraulic motor 35 is fixed by a fixed swash plate.

In the present embodiment, the HST 10 further uses the auxiliary pump unit 80 including the auxiliary pump 81 operatively driven by the drive source 5 and the pressure oil from the auxiliary pump 81 as the pair of hydraulic oils. It has a charge mechanism 610 supplied to the lines 601 and 602, and an HST speed change operating mechanism 750 that operates the output adjusting member 40 in response to an artificial operation on the speed change operating lever 700A.

As shown in FIG. 4, the auxiliary pump 81 sucks oil from an oil tank (not shown) via a suction line (not shown) and discharges pressure oil to a pressure oil supply line 605.
The hydraulic oil supply line 605 is the following HMT housing 210 of the following HMT housing 210 to which the auxiliary pump case side oil passage formed in the auxiliary pump case 83 surrounding the auxiliary pump 81 and the auxiliary pump case 83 are detachably connected. An HMT housing side oil passage formed in 1 lid member 240, one end of which is fluidly connected to the auxiliary pump case side oil passage and the other end of which is open to the outer surface to form an output port 607, and the output port 607. It has a pressure oil supply pipe 605a fluidly connected to the pipe, and is set to a predetermined hydraulic pressure by a relief valve 606. In the present embodiment, as shown in FIG. 3, the relief valve 606 is attached to the first lid member 240 and acts on the oil passage on the HMT housing side.

As shown in FIG. 4, the charge mechanism 610 has a pair of charge lines 611 and 612 whose upstream side is fluid-connected to the pressure oil supply line 605 and whose downstream side is fluid-connected to the pair of hydraulic oil lines 601 and 602, respectively. And a pair inserted in the pair of charge lines 611 and 612 so as to prevent the flow in the reverse direction while allowing the inflow of the pressure oil from the pressure oil supply line 605 to the hydraulic oil lines 601 and 602, respectively. It has check valves 615 and 616.

In the present embodiment, as shown in FIG. 4, the HST speed change operating mechanism 750 includes a hydraulic servo mechanism 760 that operates the output adjusting member 40 by using the pressure oil from the auxiliary pump 81 as the hydraulic oil. is doing.

The hydraulic servo mechanism 760 includes a cylinder 761 and a piston 763 slidably housed in the internal space of the cylinder 761 while liquidally defining the internal space of the cylinder 761 in the forward rotation chamber 761F and the reverse rotation chamber 761R. It has a switching valve 765 for switching the supply and discharge of hydraulic pressure to the forward rotation chamber 761F and the reverse rotation chamber 761R.

The switching valve 765 has a normal rotation position in which the pressure oil supply line 605 is fluidly connected to the normal rotation chamber 761F and the reverse rotation chamber 761R is fluidly connected to the drain line 609, and the normal rotation chamber 761F and the reverse rotation chamber 761R. It is now possible to selectively take a holding position for closing the pressure oil supply line 605 and a reversing position for fluidly connecting the normal rotation chamber 761F to the reverse rotation chamber 761R and fluidly connecting the normal rotation chamber 761F to the drain line 609. ing.

The piston 763 is operatively connected to the output adjusting member 40.
Specifically, when the pressure oil is supplied to the normal rotation chamber 761F and the pressure oil is discharged from the reverse rotation chamber 761R, the piston 763 is moved in the direction of expanding the normal rotation chamber 761F. On the contrary, when the pressure oil is supplied to the reverse rotation chamber 761R and the pressure oil is discharged from the normal rotation chamber 761F, the piston 763 is moved in the direction of expanding the reverse rotation chamber 761R. Then, when the forward rotation chamber 761F and the reverse rotation chamber 761R are closed, the piston 763 is held at the position at that time.

Here, when the piston 763 is moved in the direction of expanding the normal rotation chamber 761F, the output adjusting member 40 is moved to the normal rotation side, and when the piston 763 is moved in the direction of expanding the reverse rotation chamber 761R. The output adjusting member 40 is moved to the reverse side, and when the output adjusting member 40 is held at the current position, the output adjusting member 40 is operated so as to hold the output adjusting member 40 at the current position. It is connected.

When the output adjusting member 40 is moved to the normal rotation side, the output of the HST 10 is accelerated to the normal rotation side, and when the output adjusting member 40 is moved to the reverse rotation side, the output of the HST 10 is reversed. The speed is increased to the side.

The position of the switching valve 765 is controlled in response to an artificial operation of the speed change operating lever 700A.

5 (a) and 5 (b) show a front view and a side view of the speed change operation lever 700A, respectively.
Further, FIG. 6 shows a plan view of the shift operation lever 700A.

As shown in FIGS. 4 and 5A, the speed change actuating mechanism 750 is provided with an HST speed change arm 770 connected to the switching valve 765 so as to move the switching valve 765. The speed change arm 770 is operated in response to an artificial operation on the speed change operation lever 700A.

As shown in FIG. 5A, in the present embodiment, the speed change operating lever 700A is operatively connected to the HST speed change arm 770 via the mechanical link 780.

Instead of this, the HST shift operation mechanism 750 is provided with an HST shift motor such as an electric motor that operates the HST shift arm 770, and the HST shift arm 770 operates in response to an artificial operation on the shift operation lever 700A. It is also possible to control the operation of the HST shift motor so as to be performed.

As shown in FIGS. 5 and 6, the shift operation lever 700A is capable of shifting operation along the first operation direction D1 to the forward side F and the reverse side R across the zero speed position 0.

In the present embodiment, as shown in FIG. 5, the speed change operation lever 700A has a first operation shaft 710 supported by a support body 705 such as an operation box so as to be rotatable around an axis, and the first operation shaft 710. A lever body 730 whose base end is directly or indirectly supported by the first operating shaft 710 so as to be unable to rotate relative to the axis is provided, and the lever body 730 is attached to the first operating shaft 710. By swinging around the axis, it can move along the first operation direction D1.

In the present embodiment, the speed change operation lever 700A further has a grip portion 735 provided at the tip end portion of the lever body 730.

The work vehicle 1 according to the present embodiment has an operation position holding mechanism 790 that locks the speed change operation lever 700A to a desired operation position with respect to the first operation direction D1.
As shown in FIG. 5, the operation position holding mechanism 790 includes a disk 792 supported by the first operation shaft 710 so as to be relatively non-rotatable around an axis, and a pair of pads 794 arranged opposite to each other with the disk 792 interposed therebetween. It has an urging member 796 such as a coil spring that urges the pair of pads 794 in the pinching direction.

The operation position holding mechanism 790 locks the first operation shaft 710 to an arbitrary axial position by the urging force of the urging member 796, while the operating force exceeding the urging force of the urging member 796 is said. When added to the speed change operation lever 700A, the first operation shaft 710 is allowed to rotate around the axis.

In the HMT structure 200, when the speed change operation lever 700A is positioned at the zero speed position 0, the output of the HMT structure 200 (that is, the combined rotational power output from the planetary gear mechanism 100) becomes zero speed, and the speed change is achieved. As the operating lever 700A is operated from the zero speed position 0 to the forward side F and the reverse side R, the rotational power output from the planetary gear mechanism 100 is configured to be increased to the forward side and the reverse side, respectively. ing.

That is, in the HST shift operation mechanism 750, when the shift operation lever 700A is positioned at the zero speed position 0, the HST 10 outputs power at a predetermined rotation speed that causes the output of the HMT structure 200 to be zero speed. ,It is configured.

In the present embodiment, the rotation speed of the HST output that causes the output of the HMT structure 200 to be zero speed is set to the reverse rotation side predetermined rotation speed between the neutral speed and the reverse rotation side maximum speed.

Further, the HST shift operation mechanism 750 sandwiches a neutral state from the reverse rotation side predetermined rotation speed as the shift operation lever 700A is operated from the zero speed position 0 to the forward side along the first operation direction D1. As the speed is increased in the forward rotation direction and the speed change operation lever 700A is operated from the zero speed position 0 to the reverse side along the first operation direction D1, the HST output speeds up from the reverse rotation side predetermined rotation speed to the reverse rotation side. It is configured to be.

Then, in the HST 10 and the planetary gear mechanism 100, the output of the HMT structure 200 increases from the zero speed to the forward side as the HST output is increased from the reverse rotation side predetermined rotation speed in the normal rotation direction across the neutral state. The speed is increased, and the output of the HMT structure 200 is configured to be increased from the zero speed to the reverse side as the HST output is increased from the reverse rotation side predetermined rotation speed in the reverse direction.

The shift operation lever 700A can be operated from the zero speed position 0 to the brake position along the second operation direction D2 different from the first operation direction D1, in addition to the shift operation along the first operation direction D1. There is.
This point will be described later.

The planetary gear mechanism 100 inputs the rotational power from the drive source 5 to the first element and inputs the rotational power from the HST 10 to the second element, synthesizes these rotational powers, and HMTs from the third element. Output to the output shaft 350.

Specifically, the planetary gear mechanism 100 can rotate the sun gear 110, the planetary gear 120 that meshes with the sun gear 110, the internal gear 130 that meshes with the planetary gear 120, and the planetary gear 120 around the axis. It has a carrier 150 that supports and rotates around the axis of the sun gear 110 in association with the revolution of the planet gear 120 around the sun gear 110.

In the present embodiment, the internal gear 130 and the sun gear 110 act as the first and second elements, respectively, and the carrier 150 acts as the third element.

The sun gear 110 is coaxially connected to the motor shaft 30 so as to be non-rotatably around the axis.

The carrier 150 includes a carrier pin 160 that rotatably supports the planetary gear 120 and the carrier pin 160 so as to rotate around the axis of the sun gear 110 together with the revolution of the planet gear 120 around the sun gear 110. It has a carrier body 170 to support.

In the present embodiment, the carrier body 170 has first and second carrier bodies 171 and 172 that are separably connected to each other.

In the connected state, the first and second carrier main bodies 171 and 172 demarcate the space surrounding the sun gear 110, and the end portion on one side in the axial direction and the end portion on the other side in the axial direction of the carrier pin 160 are formed. I support each of them.

Specifically, the first carrier main body 171 on the side close to the HST 10 is rotatably supported by a partition wall 235 provided in the following HMT housing 210 via a bearing member, and the motor shaft 30 is inserted therethrough. It has a proximal end portion provided with an axial hole and a radial extending portion provided with a support hole extending radially outward from the proximal end portion and supporting one end side of the carrier pin 160 in the axial direction. is doing.

The second carrier main body 172 on the opposite side of the HST 10 is operably connected to the HMT output shaft 350 so as not to rotate relative to the HMT output shaft 350.
In the present embodiment, the second carrier main body 172 extends radially outward from the proximal end portion to which the HMT output shaft 350 is connected so as to be relatively non-rotatable around the axis, and the carrier pin. It has a radial extension portion provided with a support hole for supporting the other end side of the 160 in the axial direction.

In the present embodiment, the rotational power taken out from the transmission path from the drive source 5 to the pump shaft 20 is transmitted to the internal gear 130.

Specifically, as shown in FIGS. 1 and 2, the HMT structure 200 is arranged coaxially with the pump shaft 20, the upstream side in the transmission direction is operatively connected to the drive source 5, and the downstream side in the transmission direction is the pump shaft. It has an HMT input shaft 310 connected to 20 so as not to rotate relative to each other.

In the present embodiment, the HMT input shaft 310 is a hollow shaft, and an input-side transmission shaft 305 operated and connected to the drive source 5 is spline-connected on the upstream side in the transmission direction and downstream in the transmission direction. The pump shaft 20 is spline-connected to the side.

The HMT input shaft 310 is further provided with a drive-side transmission gear 312 in the middle between the upstream side and the downstream side in the transmission direction so as to be relatively non-rotatable.
In the present embodiment, the drive-side transmission gear 312 is integrally formed with the HMT input shaft 310, but of course, the drive-side transmission gear 312 is separated from the HMT input shaft 310. It is also possible to support the HMT input shaft 310 in the middle of the axial direction so that it cannot rotate relative to each other.

The internal gear 130 has a driven side transmission gear 135 that meshes with the drive side transmission gear 312, via the HMT input shaft 310, the drive side transmission gear 312, and the driven side transmission gear 135. The rotational power from the drive source 5 is input to the internal gear 130.

In the present embodiment, the internal gear 130 is supported by a base end portion that is rotatably supported on the outer peripheral surface of the base end portion of the second carrier main body 171 via a bearing member, and from the base end portion. It has an extending portion extending radially outward, a gear extending from the extending portion and engaging with the planetary gear 120, and an outer end portion provided with the driven side transmission gear 135.

As shown in FIGS. 1 and 2, the work vehicle 1 according to the present embodiment is an HMT housing 210 that houses the HST 10 and the planetary gear mechanism 100 and supports the HMT input shaft 310 and the HMT output shaft 350. have.

The HMT housing 210 is detachably connected to a mounting location (transmission 500 in this embodiment).

As shown in FIG. 2, the HMT housing 210 has a first space 211 accommodating the HST 10 and a second space 212 accommodating the planetary gear mechanism 100.

In the present embodiment, the HMT housing 210 has a housing main body 220, and a first lid member 240 and a second lid member 260 that are detachably connected to the housing main body 220.

The housing main body 220 has a hollow peripheral wall 230 having first and second openings 231 and 232 on one side and the other side in the axial direction, respectively, and the internal space of the peripheral wall 230 at an axial intermediate position of the peripheral wall 230. It has a space 211 and a partition wall 235 that partitions the second space 222.

The first lid member 240 is detachably connected to the housing body 220 so as to close the first opening 231.
As shown in FIG. 3, the first lid member 240 also acts as a port block on which the pair of hydraulic oil lines 601 and 602 are formed.

The second lid member 260 is detachably connected to the housing body 220 so as to close the second opening 232.
The second lid member 260 also acts as a mounting surface for the mounting location of the HMT housing 210 (in this embodiment, the transmission case 510 of the transmission 500).

The HMT input shaft 310 is rotatably supported around the axis by the second lid member 260 and the partition wall 235 in the second space 212.

The upstream side of the HMT input shaft 310 in the transmission direction is connected to the input side transmission shaft 305 via an access hole formed in the second lid member 260.

The pump shaft 20 has an end portion on the upstream side in the transmission direction penetrating the partition wall 235 and is connected to the downstream side in the transmission direction of the HMT input shaft 310.

In the present embodiment, as shown in FIG. 2, the end portion of the pump shaft 20 on the downstream side in the transmission direction penetrates the first lid member 240 and extends outward. The auxiliary pump 81 is supported on the extending portion.
The auxiliary pump 81 is surrounded by the auxiliary pump case 83 that is detachably connected to the HMT housing 210 (the first lid member 240) while being supported by the pump shaft 20.

The motor shaft 30 is rotatably supported around the axis by the first lid member 240 and the partition wall 235 in a state where the downstream end in the transmission direction penetrates the partition wall 235 and enters the second space 212. ing.

The HMT output shaft 350 is in a state where the upstream side in the transmission direction is connected to the carrier 150 and the downstream side in the transmission direction is accessible from the outside through an access hole formed in the second lid member 260. It is rotatably supported around the axis by 260.

As shown in FIG. 1, the work vehicle 1 according to the present embodiment further has the transmission 500 that shifts the rotational power from the HMT structure 200 and outputs the rotational power to the traveling member 6. ..

The transmission 500 includes the transmission case 510, a transmission input shaft 515 supported by the transmission case 510, an auxiliary transmission drive shaft 520 and an auxiliary transmission driven shaft 530, and the auxiliary transmission drive shaft 520 and the auxiliary transmission driven shaft 530. It has an auxiliary transmission mechanism 525 that performs multi-speed transmission between the two.

In the work vehicle 1 according to the present embodiment, the traveling members 6 are paired on the left and right.
Therefore, the transmission 500 further transfers the rotational power of the pair of drive axles 545 and 545 that output driving force toward the pair of traveling members 6 and 6 and the auxiliary transmission driven shaft 530 to the pair of drive axles. It has a differential mechanism 540 that differentially transmits to 545 and 545.

Reference numeral 535 in FIG. 1 is a parking brake mechanism that selectively applies a braking force to the auxiliary shift driven shaft 530, and reference numeral 550 selectively applies a braking force to the pair of drive axles 545 and 545. A pair of traveling brake mechanisms.

As shown in FIGS. 1, 2, 4, 4, and the like, the work vehicle 1 according to the present embodiment further has a third element (in the present embodiment, the carrier 150) which is an output element of the planetary gear mechanism 100. ) Is provided with a brake mechanism 400A capable of selectively applying a braking force.

The brake mechanism 400A is configured to apply a braking force to the third element in response to the operation of the shift operation lever 700A to the brake position.

As shown in FIGS. 5 and 6, the shift operation lever 700A moves from the zero speed position 0 to the second operation direction D2 different from the first operation direction D1 in addition to the shift operation along the first operation direction D1. It is possible to operate to the brake position along.

In the present embodiment, as shown in FIGS. 5 and 6, the speed change operating lever 700A is in a substantially orthogonal posture to the first operating shaft 710 in addition to the first operating shaft 710 and the lever main body 730. It has a supported second operating shaft 720 and a connecting member 740 supported by the second operating shaft 720.

In the connecting member 740, the lever body 730, the connecting member 740, the second operating shaft 720, and the first operating shaft 710 integrally swing around the axis of the first operating shaft 710, and the above. The base end portion of the lever main body 730 and the second operating shaft 720 are connected so that the lever main body 730 and the connecting member 740 swing around the axis of the second operating shaft 720.

With such a configuration, the lever body 730, the connecting member 740, the second operating shaft 720, and the first operating shaft 710 are integrally swung around the axis of the first operating shaft 710 to perform the shifting operation. While enabling a shift operation along the first operation direction D1 of the lever 700A, the shift operation lever is caused by the lever body 730 and the connecting member 740 integrally swinging around the axis of the second operation shaft 720. The operation along the second operation direction D2 of 700A is possible.

As shown in FIG. 5, in the present embodiment, the second operating shaft 720 penetrates the first operating shaft 710 so that one end and the other end extend outward. It is supported by one operating shaft 710.

The connection member 740 is the pair of support pieces 742 supported by one end and the other end of the second operation shaft 720, while having a gap between the first operation shaft 710 and the pair of support pieces 742. It has a connecting piece 742 that connects the support piece 742, and the base end portion of the lever body 730 is connected to the connecting piece 744.

The first operating shaft 710 is rotatably supported by the support 705 around the axis, and the lever body 730, the connecting member 740, the second operating shaft 720, and the first operating shaft 710 are integrally supported. It is rotatable around the axis of the first operation shaft 710.

Further, the second operating shaft 720 is rotatable around the axis of the first operating shaft 710, and / or the pair of support pieces 742 is rotatable about the axis of the second operating shaft 720. The lever body 730 and the connecting member 740 can swing around the axis of the second operating shaft 720 within the range in which the lever body 730 and the connecting member 740 exist.

As shown in FIG. 6, the speed change operation lever 700A further has a guide plate 800 having a guide groove 810A through which the lever body 730 is inserted.

The guide groove 810A includes the first groove 811 that guides the lever body 730 along the first operation direction D1 and the shift operation lever 700A only from the zero speed position 0 of the shift operation positions of the shift operation lever 700A. It has a second groove 812 that allows movement in the second operating direction D2.

In the present embodiment, the brake mechanism 400A is a hydraulically actuated friction plate type.
Specifically, as shown in FIG. 2, the brake mechanism 400A includes a friction plate group 405 including a rotating side friction plate that rotates with the third element and a fixed side friction plate that cannot be rotated, and the third element. The piston 410, which is movable along the axial direction and is pushed in the brake operating direction on one side in the axial direction to bring the friction plate group 405 into frictional contact, and the piston 410 are separated from the friction plate group 405. It has a return spring 415 that urges the brake in the releasing direction.

The fixed-side friction plate is supported by the HMT housing 210 in a state where the third element cannot rotate around the axis and a moving end is defined on one side of the third element toward the axis.
The rotary side friction plate is supported by the third element in a state of facing the fixed side friction plate so as to be relatively non-rotatable around the axis (integral rotation state) and movable in the axial direction.

The piston 410 is pushed in the brake operating direction in response to the operation of the speed change operating lever 700A from the zero speed position 0 to the brake position to bring the friction plate group 405 into frictional contact, whereby the third element. When the shift operation lever 700A is operated from the brake position to another operation position, the shift operation lever 700A is moved in the brake release direction by the urging force of the return spring 415.

In the present embodiment, the piston 410 is configured to be pushed in the brake operating direction by the action of hydraulic pressure in response to the operation of the speed change operating lever 700A from the zero speed position 0 to the brake position. ..

More specifically, as shown in FIG. 4, the brake mechanism 400A is further driven by the pressure oil supplied from the hydraulic source (in the present embodiment, the pressure oil supply pipe 605a forming the pressure oil supply line 605). A brake oil chamber 418 formed in the HMT housing 210 so that the piston 410 can be pushed in the brake operating direction, a hydraulic oil supply / discharge line 420 fluidly connected to the brake oil chamber 418, the hydraulic source, and the above. It includes a brake valve 425 inserted between the hydraulic oil supply / discharge lines 420, and a brake operation detection sensor 430 that detects the operation of the speed change operation lever 700A to the brake position.

The brake valve 425 selectively takes a brake operating position in which the hydraulic pressure source is fluidly connected to the hydraulic oil supply / discharge line 420 and a brake release position in which the hydraulic oil supply / discharge line 420 is fluidly connected to the drain line 422. It is configured in.

In the present embodiment, the brake valve 425 is an electromagnetic valve, and the position is controlled by the control device 900 provided in the work vehicle 1.

That is, the control device 900 recognizes that the shift operation lever 700A is operated to the brake position by the signal from the brake operation detection sensor 430 while the brake valve 425 is normally positioned at the brake release position. Then, the brake valve 425 is positioned at the brake operating position.

As the brake operation detection sensor 430, various types of sensors can be used.
In the present embodiment, as shown in FIGS. 5 and 6, the lever body 730 of the shift operation lever 700A is provided with the brake detected body 731, and the brake operation detection sensor 430 is used for the shift operation. It is a contact type sensor that comes into contact with the brake object to be detected 731 when the lever 700A is positioned at the brake position.

As described above, in the work vehicle 1 according to the present embodiment, when the shift operation lever 700A is positioned at the zero speed position 0, the rotational power of the third element of the planetary gear mechanism 100 becomes zero speed, and the shift is performed. When the operation lever 700A is operated from the zero speed position 0 to the forward side F and the reverse side R, the rotational power of the third element of the planetary gear mechanism 100 rotates and drives the traveling member 6 to the forward side, respectively. It becomes the power and the reverse rotation power that drives the rotation to the reverse side.
Therefore, forward traveling and reverse traveling can be performed without separately providing a forward / backward switching mechanism.

By the way, in a work vehicle in which the output of the HMT structure 200 can be switched in the forward / backward direction as in the work vehicle 1 according to the present embodiment, it is practically possible to set the output of the HMT structure 200 to the zero speed state. Have difficulty.

That is, in the above-mentioned type of work vehicle, the HST and the planetary gear mechanism are configured so that the output of the HMT structure is in the zero speed state when the HST output is set to a preset predetermined rotation speed. In the present embodiment, as described above, the HST 10 and the planetary gear mechanism 100 are configured so that the output of the HMT structure 200 is in a zero speed state when the HST 10 has a predetermined rotation speed on the reverse side. Has been done.

That is, in order to display the output zero speed state of the HMT structure in the work vehicle of the above type, the shift operation lever is positioned at the operation position corresponding to the predetermined rotation speed (zero speed position 0 in the present embodiment). At that time, the manufacturing of the HST and the construction of the operation relationship between the HST and the speed change operation lever are accurate so that the HST output becomes a predetermined rotation speed (in the present embodiment, the reverse rotation side predetermined rotation speed). Furthermore, it is necessary to accurately manufacture the HMT structure so that the output of the HMT structure becomes zero speed when the HST outputs a rotation speed of a predetermined rotation speed.

For example, if a manufacturing error and / or an assembly error occurs in the HST or planetary gear mechanism, the HMT structure outputs low-speed rotational power even though the speed change operation lever is positioned at the operation position corresponding to the predetermined rotation speed. Then, the problem that the working vehicle moves at creep speed may occur.

In this regard, as described above, the work vehicle 1 according to the present embodiment brakes along the second operation direction D2 in a state where the shift operation lever 700A is not moved from the zero speed position 0 to the first operation direction D1. When operated to a position, the brake mechanism 400A is configured to apply a braking force to a third element (the carrier 150 in the present embodiment) which is an output element of the planetary gear mechanism 100.
Therefore, it is possible to reliably prevent the work vehicle 1 from moving at a creep speed unexpectedly.

The work vehicle 1 according to the present embodiment further operates the pair when the speed change operating lever 700A is operated to the brake position while blocking between the pair of hydraulic oil lines 601 and 602 in a normal state. A bypass mechanism 450 for communicating between the oil lines 601 and 602 is provided.
By providing the bypass mechanism 450, the capacity of the brake mechanism 400A can be reduced.

That is, when the pair of hydraulic oil lines 601 and 602 are communicated with each other, the hydraulic drive of the hydraulic motor 35 by the hydraulic pump 25 becomes impossible, and the hydraulic motor 35 becomes substantially rotatable.

In this state, the third element of the planetary gear mechanism 100 is also in a free state that can rotate around the axis.
Therefore, the rotation of the third element can be stopped with a small braking force, and the capacity of the brake mechanism 400A can be reduced.

In the work vehicle 1 according to the present embodiment, as shown in FIGS. 3 and 4, the bypass mechanism 450 connects to the bypass line 455 communicating with the pair of hydraulic oil lines 601 and 602 and the bypass line 455. It is equipped with a bypass valve 460 inserted.

The bypass valve 460 has a bypass position in which the bypass line 450 is in a communicating state to communicate between the pair of hydraulic oil lines 601 and 602, and the bypass line 455 is in a shutoff state in the pair of hydraulic oil lines. It is configured so that a blocking position for blocking between 601 and 602 can be selectively taken.

In the present embodiment, the bypass valve 460 is a solenoid valve whose position is controlled by the control device 900.

That is, the control device 900 recognizes that the shift operation lever 700A is operated to the brake position by the signal from the brake operation detection sensor 430 while the bypass valve 460 is normally positioned at the cutoff position. , The bypass valve 460 is positioned at the communication position.

In the present embodiment, the bypass valve 460 is an electromagnetic valve whose position is electrically controlled by the control device 900, but instead, the bypass valve 460 is set to zero of the speed change operation lever 700A. It is also possible to transform the position by a mechanical link by utilizing the movement from the speed position 0 to the brake position.

FIG. 7 shows a plan view of the speed change operation lever 700B provided in the work vehicle according to the first modification of the present embodiment.
In FIG. 7, the same members as those in the present embodiment are designated by the same reference numerals.

In the first modification, the guide groove 810A is changed to the guide groove 810B, the shift operation lever 700A is changed to the shift operation lever 700B, and the bypass position of the shift operation lever 700B. It differs from the present embodiment in that it is provided with a bypass operation detection sensor 432 that detects the operation to.

As shown in FIG. 7, the shift control lever 700B can be operated from the brake position to the bypass position along the first operation direction D1 in addition to the movement of the shift control lever 700A.

The guide groove 810B, in addition to the first groove 811 and the second groove 812, allows the shift operation lever 700B to move from the brake position to the bypass position along the first operation direction D1. It has a groove 813.

The shift operation lever 700B further has a bypass detected body 732 detected by the bypass operation detection sensor 432 as compared with the shift operation lever 700A.

In the first modification, when the shift operation lever 700B is operated from the brake position to the bypass position, the communication state between the pair of hydraulic oil lines 601 and 602 by the bypass mechanism 450 is maintained. It is configured to release the braking force applied to the third element by the brake mechanism 450A.

Specifically, the brake detected body 731 is detected by the brake operation detection sensor 430 when the shift operation lever 700B is positioned at the brake position, while the shift operation lever 700B brakes. The size is such that when the brake operation detection sensor 430 is operated from the position to the bypass position, the brake operation detection sensor 430 is separated from the brake operation detection sensor 430.

According to the first modification, the brake mechanism 400A applies a braking force to the third element while blocking the power transmission from the hydraulic motor 35 to the planetary gear mechanism 100 by the bypass mechanism 450. In addition to a state of preventing movement at a creep speed contrary to the intention of the work vehicle, the third element is made a rotatable free state while releasing the braking force applied to the third element by the brake mechanism 400A. The HMT rotation free state can be revealed.

By setting the third element of the planetary gear mechanism to the free state and displaying the HMT rotation free state, the work vehicle can be forcibly towed.

That is, when a work vehicle provided with the HMT structure 200 is forcibly towed in the traveling system transmission path, the hydraulic motor 35 of the HST 10 operated and connected to the traveling member 6 is forcibly rotated by the forced rotation of the traveling member 6. become.

On the other hand, the hydraulic pump 25 of the HST 10 to which the hydraulic motor 35 is fluidly connected via a pair of hydraulic oil lines 601 and 602 is operatively connected to a drive source 5 such as an engine and cannot rotate freely. It has become.

Therefore, when the hydraulic motor 35 is forcibly rotated with the rotation of the traveling member 6 when the work vehicle is towed, the hydraulic pump 25 cannot freely rotate due to the operational connection with the drive source 5. The oil discharged from the hydraulic motor 35 will flow into one of the pair of hydraulic oil lines 601 and 602, and the hydraulic pressure of the one hydraulic oil line 601 and 602 hinders the rotation of the hydraulic motor 35. ..

Regarding this point, in the first modification, the bypass mechanism 450 is in a state where the braking force to the third element of the planetary gear mechanism 100 is released by operating the shift operation lever 700B to the bypass position. The HMT rotation-free state in which the pair of hydraulic oil lines 601 and 602 are communicated with each other appears.

In this state, the third element operatively connected to the traveling member 6 can freely rotate around the axis line, and therefore, the work vehicle can be forcibly towed.

FIG. 8 shows a plan view of the speed change operation lever 700C provided in the work vehicle according to the second modification of the present embodiment.
In FIG. 8, the same members as those in the present embodiment and the first modification are designated by the same reference numerals.

In the second modification, the guide groove 810A is changed to the guide groove 810C, the shift operation lever 700A is changed to the shift operation lever 700C, and the bypass position of the shift operation lever is reached. This embodiment is different from the present embodiment in that a bypass operation detection sensor for detecting the operation of the above is provided.

As shown in FIG. 8, the shift operation lever 700C can be operated from the zero speed position to the bypass position on the other side of the second operation direction D2 in addition to the movement of the shift operation lever 700A.

In addition to the first groove 811 and the second groove 812, the guide groove 810C has a third groove 814 that allows the speed change operation lever 700C to be moved from the zero speed position 0 to the bypass position. ..

The shift operation lever 700C further has a bypass detected body 732 detected by the bypass operation detection sensor 432 as compared with the shift operation lever 700A.

In the second modification, when the speed change operation lever 700C is operated from the zero speed position 0 to the brake position on one side in the second operation direction, the bypass mechanism is the same as in the present embodiment and the first modification. A state appears in which the brake mechanism 400A applies a braking force to the third element to prevent the working vehicle from moving at a creep speed contrary to the intention of the work vehicle, while the third element is made rotatable and free by the 450. Further, when the speed change operation lever is operated from the zero speed position to the bypass position on the other side in the second operation direction, the bypass mechanism is released in a state where the braking force applied to the third element by the brake mechanism 400A is released. The HMT rotation-free state in which the third element is rotatable by the 450 appears.

Embodiment 2
Hereinafter, other embodiments of the working vehicle according to the present invention will be described with reference to the accompanying drawings.
FIG. 9 shows a plan view of the speed change operation lever 700D provided in the work vehicle according to the present embodiment.
In the figure, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The work vehicle according to the present embodiment has a shift operation lever 700D instead of the shift operation lever 700A as compared with the work vehicle according to the first embodiment.

As shown in FIG. 9, the shift operation lever 700D performs a shift operation of moving along the first operation direction D1 and a bypass operation of moving from the zero speed position 0 to the bypass position along the second operation direction D2. It is configured to be able to do it.

The working vehicle is configured to communicate only between the pair of hydraulic oil lines 601 and 602 by the bypass mechanism 450 in response to the operation of the speed change operating lever 700D to the bypass position.

According to the working vehicle having such a configuration, by operating the shifting operation lever 700D to the bypass position, the working vehicle can be in a state where it can be towed.

As shown in FIG. 9, in the work vehicle according to the present embodiment, in the bypass operation detection sensor 432, the speed change operation lever 700D is operated from the zero speed position to the bypass position along the second operation direction D2. It is arranged so that the bypass detected body 732D provided on the speed change operation lever 700D can be detected.

Then, the control device 900 positions the bypass valve 460 at the communication position in response to the detection signal from the bypass operation detection sensor 432.

The shift operation lever 700D is further configured to perform a brake operation for moving from the bypass position to the brake position along the first operation direction D1.

In response to the operation of the shift operation lever 700D to the brake position, the work vehicle maintains the communication between the pair of hydraulic oil lines 601 and 602 by the bypass mechanism 450, and the brake mechanism 400A performs the first. It is configured to add braking force to the three elements.

By providing such a configuration, by operating the shift operation lever 700D from the bypass position to the brake position, the work vehicle can move at an unexpected creep speed while reducing the capacity of the brake mechanism 400A. It can be reliably prevented.

As shown in FIG. 9, in the work vehicle according to the present embodiment, the brake operation detection sensor 430 is operated when the shift operation lever 700D is operated from the bypass position to the brake position along the first operation direction D1. The brake object to be detected 731 provided on the speed change operation lever 700D is arranged so as to be able to be detected.

Here, the bypass detected body 732D maintains the detection state by the bypass operation detection sensor 432 even when the shift operation lever 700D is moved from the bypass position to the brake position along the first operation direction D1. Has a large size.

In each of the embodiments, the brake mechanism 400A is a hydraulically actuated friction plate type, but the present invention is not limited to such a mode, as a matter of course.

FIG. 10 shows a partial cross-sectional view of the HMT structure 200B provided with the brake mechanism 400B according to the modified example.
Further, FIG. 11 shows a cross-sectional view taken along the line XI-XI in FIG.
In the figure, the same members as those in the embodiment are designated by the same reference numerals.

The brake mechanism 400B includes the friction plate group 405, a piston 410B that brings the friction plate group 405 into frictional contact by being pushed in the brake operating direction on one side in the axial direction of the third element, and the return spring. It has a 415 and a pushing member 850 that pushes the piston 410B in the brake operating direction against the urging force of the return spring 415.

The piston 410B is housed in an HMT housing 210 accommodating the planetary gear mechanism 100 so as to be rotatable around the axis and movable in the axial direction of the third element, and is housed on the tip side in contact with the friction plate group 405. It has an end surface 411 and a base end side end surface 412 facing the opposite side of the friction plate group 405.

The pushing member 850 is supported by the HMT housing 210 so as to be rotatable around the axis along the axial direction of the third element with the tip end side engaged with the piston 410B and the proximal end side accessible from the outside. The piston 410B is configured to rotate around the axis of the third element by being rotated around the axis.

Specifically, the pushing member 850 has a shaft portion 851 rotatably supported around the axis of the HMT housing 210, and an engaging portion 852 having a non-circular cross section provided on the tip end side.

The piston 410B is provided with a pressure receiving surface 413 that is engaged with the engaging portion 852, and when the pushing member 850 is rotated around the axis of the shaft portion 851, the engaging portion 852 is said to be the same. The piston 410B is rotated around the axis of the third element via the pressure receiving surface 413.

An engagement groove 414 along the circumferential direction is formed on the base end side end surface of the piston 410B.
The engagement groove 414 has a deepest portion 414a and an inclined portion 414b that becomes shallower from the deepest portion 414a toward one side in the circumferential direction.

The HMT housing 210 is provided with a convex body 855 engaged in the engagement groove 414 on the inner wall surface facing the base end side end surface 412 so as not to move around the axis of the third element.
In the present embodiment, the convex body 855 is a rolling element housed in a concave portion formed on the inner wall surface of the HMT housing 210 so as to be rollable around its own center.

The brake mechanism 410B operates as follows.
When the pushing member 850 is rotated around the axis of the shaft portion 851, the piston 410B is rotated around the axis via the engaging portion 852. When the piston 410B is rotated about an axis, the convex body 855 moves in the engaging groove 414 in the circumferential direction relatively from the deepest portion 414a to the inclined portion 414b.
As a result, the piston 410B is moved in the brake pushing direction against the urging force of the return spring 415, and the friction plate group 405 is brought into frictional contact.
Reference numeral 860 in FIGS. 10 and 11 is a brake operation arm fixed to the base end side of the pushing member 850.

FIG. 12 shows a cross-sectional view of the HMT structure 200C provided with the brake mechanism 400C according to another modification.
Further, FIG. 13 shows a cross-sectional view taken along the line XIII-XIII in FIG.
In the figure, the same members as those in the embodiment and the modification are designated by the same reference numerals.

The brake mechanism 400C is a band type.
Specifically, the brake mechanism 400C includes a band body 870 arranged so as to surround the outer periphery of the third element in a state where one end is a fixed end 871 and the other end is a movable end 872. A rotation shaft 875 supported by the HMT housing 210 so as to be rotatable around the axis along the axis direction of the third element with the tip side plunged into the internal space of the HMT housing 210 and the base end side accessible from the outside. It has a brake arm 880 whose end is connected to the tip end side of the rotation shaft 875 so as not to be relatively rotatable and whose tip end is connected to the movable end 872 of the band body 870.

When the rotating shaft 875 is rotated in the brake operating direction on one side around the axis, the band body 870 is reduced in diameter via the brake arm 880, whereby the diameter of the band body 870 is reduced, and the diameter of the band body 870 is reduced to the outer peripheral surface of the third element. Braking force is added to the third element by the frictional force.

When the rotation shaft 875 is rotated in the brake release direction on the other side around the axis, the band body 870 is expanded in diameter via the brake arm 880, and the braking force on the third element is released.

The rotation of the push member 850 and the rotation shaft 875 around the axis can be performed by an electric actuator such as an electric motor whose operation is controlled by the control device 900, and the shift operation levers 700A to 700D can be rotated. It is also possible to do this by transmitting the movement to the brake position via a mechanical link.

1 Work vehicle 5 Drive source 6 Traveling member 10 HST
100 Planetary gear mechanism 400A-400C Brake mechanism 450 Bypass mechanism 601 and 602 Hydraulic oil line 700A-700D Speed change operation lever 710 1st operation shaft 720 2nd operation shaft 730 Lever body 740 Connection member D1 1st operation direction D2 2nd operation direction

Claims (4)

The drive source, the HST that continuously shifts and outputs the rotational power input from the drive source, and the rotational power from the drive source and the rotational power from the HST are input to the first and second elements, respectively. A planetary gear mechanism that synthesizes the rotational powers of the first and second elements and outputs them from the third element, a traveling member operatively driven by the rotational power output from the planetary gear mechanism, and the HST are speed-shifted. It is a work vehicle equipped with a shift operation lever to operate,
A brake mechanism capable of selectively applying a braking force to the third element of the planetary gear mechanism , and
A bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST is provided.
The speed change operation lever moves from the zero speed position to the forward side and the reverse side along the first operation direction in addition to the shift operation along the second operation direction different from the first operation direction. It is possible to operate to the brake position and from the brake position to the bypass position along the first operation direction .
In the HST and the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the speed change operation lever moves forward and backward from the zero speed position. It is configured so that the rotational power output from the planetary gear mechanism is accelerated to the forward side and the reverse side as it is operated to the side.
When the shift operation lever is shifting along the first operation direction, the brake mechanism releases the braking force on the third element , and the bypass mechanism is the pair of hydraulic oils. Block between the lines ,
When the shift control lever is operated to the brake position, the brake mechanism applies a braking force to the third element , and the bypass mechanism communicates between the pair of hydraulic oil lines.
When the shift control lever is operated to the bypass position, the braking force of the brake mechanism on the third element is released while the communication between the pair of hydraulic oil lines by the bypass mechanism is maintained. A work vehicle characterized by being configured in. The drive source, the HST that continuously shifts and outputs the rotational power input from the drive source, and the rotational power from the drive source and the rotational power from the HST are input to the first and second elements, respectively. A planetary gear mechanism that synthesizes the rotational powers of the first and second elements and outputs them from the third element, a traveling member operatively driven by the rotational power output from the planetary gear mechanism, and the HST are speed-shifted. It is a work vehicle equipped with a shift operation lever to operate,
A brake mechanism capable of selectively applying a braking force to the third element of the planetary gear mechanism, and
A bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST is provided.
The speed change operation lever moves from the zero speed position to the forward side and the reverse side along the first operation direction along the second operation direction different from the first operation direction, in addition to the shift operation along the first operation direction. It is possible to operate to the brake position and from the zero speed position to the bypass position on the opposite side of the brake position along the second operation direction.
In the HST and the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the speed change operation lever moves forward and backward from the zero speed position. It is configured so that the rotational power output from the planetary gear mechanism is accelerated to the forward side and the reverse side as it is operated to the side.
In the brake mechanism, when the shift operation lever is shifting operation along the first operation direction, the shift operation lever is operated to the brake position while releasing the braking force on the third element. And is configured to add braking force to the third element.
When the shift operation lever is shifting along the first operation direction, the brake mechanism releases the braking force to the third element, and the bypass mechanism is of the pair of hydraulic oil lines. Cut off the gap,
When the shift control lever is operated to the brake position, the brake mechanism applies a braking force to the third element, and the bypass mechanism communicates between the pair of hydraulic oil lines.
When the shift control lever is operated to the bypass position, the brake mechanism releases the braking force to the third element, and the bypass mechanism communicates between the pair of hydraulic oil lines. Work vehicle to do . The drive source, the HST that continuously shifts and outputs the rotational power input from the drive source, and the rotational power from the drive source and the rotational power from the HST are input to the first and second elements, respectively. A planetary gear mechanism that synthesizes the rotational powers of the first and second elements and outputs them from the third element, a traveling member operatively driven by the rotational power output from the planetary gear mechanism, and the HST are speed-shifted. It is a work vehicle equipped with a shift operation lever to operate,
A bypass mechanism capable of switching between shutoff and communication between a pair of hydraulic oil lines in the HST ,
A brake mechanism that selectively applies a braking force to the third element of the planetary gear mechanism is provided.
The shift operation lever moves the shift operation lever from the zero speed position to the forward side and the reverse side along the first operation direction in addition to the shift operation along the second operation direction different from the first operation direction. It is possible to operate to the bypass position and from the bypass position to the brake position in a direction different from the zero speed position .
In the HST and the planetary gear mechanism, when the speed change operation lever is positioned at the zero speed position, the rotational power output from the planetary gear mechanism becomes zero speed, and the speed change operation lever moves forward and backward from the zero speed position. It is configured so that the rotational power output from the planetary gear mechanism is accelerated to the forward side and the reverse side as it is operated to the side.
When the speed change operation lever is changed speed along the first operation direction, the bypass mechanism cuts off between the pair of hydraulic oil lines , and the brake mechanism moves to the third element. Release the braking force of
When the shift control lever is operated to the bypass position, the bypass mechanism communicates between the pair of hydraulic oil lines , and the brake mechanism releases the braking force to the third element.
When the shift control lever is positioned at the brake position, the brake mechanism is configured to apply braking force to the third element while maintaining communication between the pair of hydraulic oil lines by the bypass mechanism. A work vehicle characterized by being. The shift operation lever includes a first operation shaft rotatably supported around an axis, a second operation shaft supported in a state orthogonal to the first operation shaft, an artificially operated lever body, and the lever body. It has a connecting member that connects the base end portion to the second operating shaft, and the lever body, the connecting member, the second operating shaft, and the first operating shaft are integrally around the axis of the first operating shaft. The second operation is performed by rotating the lever body and the connecting member around the axis of the second operation shaft, while the shifting operation is performed along the first operation direction. The work vehicle according to any one of claims 1 to 3 , wherein the operation is performed along the direction.

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