JP6628842B2 - Gearing - Google Patents

Description

  The present invention relates to a transmission device provided in a tractor for transmitting power output from an engine to a traveling device and a working device.

  Conventionally, as the above-mentioned transmission, for example, there has been one described in Patent Document 1. In the transmission described in Patent Document 1, power output from the engine is transmitted through a dry clutch mechanism, an HST as a hydrostatic continuously variable transmission mechanism, a planetary gear mechanism, a forward / reverse switching mechanism, and an auxiliary transmission mechanism in this order. And transmitted to the rear wheel drive shaft.

JP 2012-40944 A

When the above-described transmission is used for a tractor, the following problem may occur.
Since a large tractor outputs a large amount of power from the engine, the dry clutch mechanism as a clutch function is subject to severe wear and the frequency of replacement tends to be high.
Therefore, it is conceivable that a dry clutch mechanism is not provided. In this case, the clutch function depends on the wet clutch mechanism provided in the forward / reverse switching mechanism.
However, since the forward / reverse switching mechanism is disposed downstream of the planetary gear mechanism, when the engine is started, the HST, the planetary gear mechanism, and the wet clutch of the forward / reverse switching mechanism are integrally formed when the engine is started. Need to rotate. Since the inertial force and the resistance torque of the HST, the planetary gear mechanism and the forward / reverse switching mechanism up to the wet clutch are large, a large load torque is applied to the starter, and the size of the starter needs to be increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission capable of avoiding an increase in the size of a starter by reducing a load torque at the time of starting an engine.

A feature of the transmission according to the present invention for achieving the above object is a transmission provided in a tractor for transmitting power output from an engine to a traveling device and a working device, comprising a forward / reverse switching mechanism, a hydrostatic IVT equation, the planetary gear mechanism comprises a rear wheel drive and work clutch, the forward-reverse switching mechanism, reverse switching mechanism input before the power output from the engine output unit the engine has is input And a forward / reverse switching mechanism output section for switching the power input to the forward / reverse switching mechanism input section to forward rotation or reverse rotation and outputting the same, and wherein the continuously variable transmission mechanism outputs the forward / reverse switching mechanism output. A continuously variable transmission mechanism input unit to which the power output from the unit is input, and a continuously variable transmission mechanism output unit that continuously varies the power input to the continuously variable transmission mechanism and outputs the power. Gear mechanism The planetary gear mechanism first input unit to which the power output from the continuously variable transmission mechanism output unit is input, and the power output from the forward / reverse switching mechanism output unit are continuously variable by the continuously variable transmission mechanism. Planetary gear mechanism second input unit, and the planetary gear mechanism output unit that combines the powers input to the planetary gear mechanism first input unit and the planetary gear mechanism second input unit, and outputs the combined power. The rear wheel drive unit has a rear wheel drive unit input unit to which the power output from the planetary gear mechanism output unit is input, and the work clutch is output from the engine output unit. a work clutch input unit to which power is inputted, have a said work clutch input unit can be output to the power input to the work clutch output unit, the continuously variable transmission mechanism, to the rear than the forward-reverse switching mechanism , And said The planetary gear mechanism is disposed forward of the star gear mechanism, and includes a forward-reverse switching mechanism input section, the planetary gear mechanism first input section, the planetary gear mechanism second input section, the planetary gear mechanism output section, and the work clutch input section. Each rotation axis is disposed on the same first axis, and when viewed from the front of the tractor, the rotation axis of the continuously variable transmission mechanism input portion is disposed on one side in the left-right direction with respect to the first axis. is the rotation axis of the CVT output unit lies in that is disposed in the lateral direction other with respect to said first axis.

  According to the above-described configuration, the forward / reverse switching mechanism is disposed immediately after the engine. When the engine is started, the forward / reverse switching mechanism can realize a state in which power output from the engine output unit is not transmitted to each mechanism downstream of the forward / reverse switching mechanism. For this reason, it is possible to avoid an increase in load torque as in the case where the forward / reverse switching mechanism is disposed downstream of the planetary gear mechanism, and it is possible to avoid an increase in the size of the starter. The size increase of the starter is avoided. This avoids an increase in the space occupied by the starter, the battery, the harness, and the like, and an increase in cost.

The continuously variable transmission mechanism has at least a hydraulic pump, a hydraulic motor, a hydraulic circuit disposed therebetween, and a mechanism such as a hydraulic cylinder for driving a swash plate of the hydraulic pump, and requires a certain installation space. . If the continuously variable transmission mechanism is arranged closer to one of the left and right sides of the first axis when viewed from the front of the tractor, the body frame on the side where the continuously variable transmission mechanism is disposed is strengthened or the vehicle width is increased. Or it becomes necessary.
The hydraulic pump having the pump shaft as the continuously variable transmission mechanism input unit and the hydraulic motor having the motor shaft as the continuously variable transmission mechanism output unit are divided into right and left with respect to the rotation axis of the engine output unit in a front view of the tractor. By arranging the vehicle frames, it is not necessary to reinforce the vehicle frame in the right and left directions and to increase the vehicle width in the left and right directions.

Side view showing the entire tractor Block diagram showing transmission Skeleton diagram showing transmission Explanatory diagram showing the positional relationship of each axis

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing the entire tractor according to the embodiment of the present invention. Although the tractor according to the embodiment of the present invention is not particularly limited, it is a tractor classified into a large size, for example, about 60 to 100 horsepower.
The tractor includes a pair of left and right steering wheels 1 that can be driven and driven, a pair of left and right wheels that can be driven, a driving unit 3 having an engine 3a provided at the front of the vehicle body, and a driver seat provided at the rear of the vehicle body. A link mechanism 6 having a pair of left and right vertically oscillating lift arms 6a provided on both sides of a rear end portion of a body frame 5 on a self-propelled vehicle provided with a driving unit 4 having 4a; A power take-off shaft 7 protruding rearward from the rear end of the frame 5 is provided. The power take-out shaft 7 is a power take-out part.

In this tractor, a rotary tillage device (not shown) is connected to the rear of the vehicle body via a link mechanism 6 so as to be able to move up and down freely, and power output from the engine 3a is transmitted from a power take-out shaft 7 to an input shaft of the rotary tillage device. By being configured to transmit power, for example, a riding cultivator is configured. The input shaft of the rotary tilling device is a working device input unit.
As described above, various working devices are connected to the rear part of the vehicle body so as to be able to move up and down and to be freely driven, thereby constituting various riding type working machines.

  The vehicle body frame 5 includes an engine 3a, a clutch housing 10 connected to a rear portion of the engine 3a, a continuously variable transmission case 21 having a front portion detachably connected to a rear portion of the clutch housing 10, and a continuously variable transmission case 21. A transmission case 11 and the like connected to the rear of the case 21 are provided. Although the clutch housing 10 and the continuously variable transmission case 21 are integrally formed, the inside is divided into two regions by an internal partition. Note that the clutch housing 10 and the continuously variable transmission case 21 may be configured separately, and the front wall of the continuously variable transmission case 21 may be detachably connected to the rear wall of the clutch housing 10.

  2 and 3 show a transmission device D provided on a tractor so as to transmit the power output from the engine 3a to the front wheel 1, the rear wheel 2 and the power take-off shaft 7.

As shown in FIG. 2, the transmission D includes a traveling transmission D1 and a work transmission D2.
The traveling-system transmission device D1 uses the power output from the engine 3a to move forward and backward, such as a forward / reverse switching mechanism 50, a main transmission mechanism, a hydrostatic stepless transmission mechanism 20, a planetary gear mechanism 40, and an auxiliary transmission mechanism. The power is transmitted to traveling devices such as the front wheels 1 and the rear wheels 2 via the wheel 60.
The work system transmission device D2 transmits the power output from the engine 3a to a work device such as a rotary tilling device via the work clutch 70, the work transmission mechanism 71, and the power take-out shaft 7.

The details of the transmission D will be described with reference to FIG.
The traveling system transmission D1 inputs the power output from the output shaft 3b by the engine 3a to the continuously variable transmission mechanism 20 and the planetary gear mechanism 40 via the forward / reverse switching mechanism 50, and outputs the output shaft 48 of the planetary gear mechanism 40. From the auxiliary transmission mechanism 60, from the output shaft 64 of the auxiliary transmission mechanism 60 to the rear wheel shaft 31 via the rear wheel drive shaft 32 and the rear wheel differential mechanism 33, and from the auxiliary transmission mechanism 60 Power is transmitted to a front wheel differential mechanism 38 via an interlocking mechanism 34, a front wheel drive shaft 35, a front wheel speed change mechanism 36, and a front wheel speed change drive shaft 37. The output shaft 3b is an engine output unit. The rear wheel shaft 31, the rear wheel drive shaft 32, the rear wheel differential mechanism 33, and the like are rear wheel drive units that drive the rear wheels 2, and the rear wheel drive shaft 32 is a rear wheel drive unit input unit. The output shaft 48 is a planetary gear mechanism output unit.

  The work system transmission device D2 inputs the power output from the output shaft 3b by the engine 3a to the work transmission mechanism 71 via the work clutch 70, shifts the power to a plurality of stages, and transmits the changed power to the power take-out shaft 7. The working clutch 70 includes an input-side clutch plate rotatably provided on an input-side power transmission shaft 72a integrally rotatably connected to the output shaft 3b via a forward / reverse switching mechanism 50 to be described later; When the output-side clutch plate rotatably provided on the transmission shaft 72b is pressed or separated, the power of the input-side power transmission shaft 72a can be output from the output-side power transmission shaft 72b or not. The input-side power transmission shaft 72a is a work clutch input unit, and the output-side power transmission shaft 72b is a work clutch output unit.

  The forward / reverse switching mechanism 50 is provided in the clutch housing 10 provided at the front of the continuously variable transmission case 21. The continuously variable transmission mechanism 20 is disposed on a continuously variable transmission case 21 connected to the front of the front transmission case 11a. The planetary gear mechanism 40 is disposed on the front transmission case 11a. The auxiliary transmission mechanism 60, the rear wheel differential mechanism 33, the front wheel transmission mechanism 36, the front wheel differential mechanism 38, the work clutch 70, and the work transmission mechanism 71 are arranged in the rear transmission case 11b.

  The forward / reverse switching mechanism 50 is configured to rotate the power of the input shaft 51 integrally with the transmission gear 54 via a forward clutch 52 and a forward output gear 53 via an input shaft 51 that is rotatably connected to the output shaft 3b of the engine 3a. The power of the input shaft 51 is transmitted to the output shaft 55 that rotates integrally with the transmission gear 54 via the reverse clutch 56, the transmission gear 57, the reverse rotation gear 58, and the reverse output gear 59. And a reverse transmission. Note that the input shaft 51 is a forward / reverse switching mechanism input unit, and the output shaft 55 is a forward / reverse switching mechanism output unit.

Therefore, the forward / reverse switching mechanism 50 is brought into the forward state by operating the forward clutch 52 in the on state and the reverse clutch 56 in the off state, and is transmitted from the output shaft 3b of the engine 3a to the input shaft 51. The generated power is converted into forward power by a forward transmission unit and output from the output shaft 55 to the continuously variable transmission mechanism 20.
The forward / reverse switching mechanism 50 is set in the reverse state by operating the forward clutch 52 in the disengaged state and operating the reverse clutch 56 in the engaged state, and the power transmitted from the output shaft 3b of the engine 3a to the input shaft 51 is changed. Is converted into reverse power by the reverse transmission and output from the output shaft 55 to the continuously variable transmission mechanism 20.
When the forward clutch 52 and the reverse clutch 56 are operated to be in the disengaged state, the forward / reverse switching mechanism 50 is in a state where power is not transmitted, and the power transmitted from the output shaft 3b of the engine 3a to the input shaft 51 is output to the output shaft. No signal is output from 55 to the continuously variable transmission mechanism 20. The forward clutch 52 and the reverse clutch 56 are formed by wet clutches.

  At the time of starting the engine 3a, a state in which the power of the engine 3a is not transmitted to each mechanism after the forward / reverse switching mechanism 50 by the forward / reverse switching mechanism 50 can be realized. As a result, it is possible to avoid an increase in load torque as in the case where the forward / reverse switching mechanism 50 is disposed downstream of the planetary gear mechanism 40, and it is possible to avoid an increase in the size of the starter. By avoiding an increase in the size of the starter, an increase in the space occupied by the starter, the battery, the harness, and the like and an increase in cost are avoided.

  The continuously variable transmission mechanism 20 includes a hydraulic pump 20P and a hydraulic motor 20M inside a continuously variable transmission case 21. The hydraulic pump 20P and the hydraulic motor 20M are arranged inside the continuously variable transmission case 21 in the lateral direction of the vehicle body in a plan view of the vehicle body. The hydraulic pump 20P is constituted by a variable displacement and axial plunger type hydraulic pump, and the hydraulic motor 20M is constituted by an axial plunger type hydraulic motor. The continuously variable transmission case 21 includes a port plate (not shown).

  In the continuously variable transmission mechanism 20, the power output from the output shaft 55 of the forward / reverse switching mechanism 50 is input to the pump shaft 22 of the hydraulic pump 20P, and the cylinder block of the hydraulic pump 20P is rotationally driven by the pump shaft 22. 20P supplies hydraulic oil to the hydraulic motor 20M, and the cylinder block of the hydraulic motor 20M is rotationally driven by the hydraulic oil from the hydraulic pump 20P to rotate the motor shaft 25, and outputs the motor shaft 25 to the planetary gear mechanism 40. It is configured as follows. The pump shaft 22 is an input of the continuously variable transmission mechanism, and the motor shaft 25 is an output of the continuously variable transmission mechanism.

In the continuously variable transmission mechanism 20, the angle of the swash plate 27 is changed by the hydraulic cylinder by operating a hydraulic cylinder that is interlocked with the swash plate 27 of the hydraulic pump 20P. The rotational speed of the hydraulic pump 20P is steplessly changed regardless of whether the gear is shifted to a neutral state located between the forward rotation state and the reverse rotation state, and also to the forward rotation state or the reverse rotation state. Then, the rotation speed of the hydraulic motor 20M is changed steplessly, and the rotation speed of the power output from the motor shaft 25 to the planetary gear mechanism 40 is changed steplessly.
When the speed is changed to the neutral state, the continuously variable transmission mechanism 20 stops driving the hydraulic motor 20M by the hydraulic pump 20P and stops the output from the motor shaft 25 to the planetary gear mechanism 40.

  The planetary gear mechanism 40 receives the power output from the continuously variable transmission mechanism 20 via a bearing into a planetary gear case 41 provided inside the front transmission case 11a. The boss 43a is rotatably supported. Forward / backward switching for supporting the sun gear 43, three planetary gears 44 scattered at equal intervals around the sun gear 43, and rotatably supporting each planetary gear 44 via a support shaft 45. The power output from the mechanism 50 is input by the continuously variable transmission mechanism 20 without being continuously variable, and the carrier 46, the ring gear 47 meshing with the three planetary gears 44, and the planetary gear case 41 via bearings. And an output shaft 48 rotatably supported. The sun gear 43 is a planetary gear mechanism first input unit, and the carrier 46 is a planetary gear mechanism second input unit.

The carrier 46 is rotatably supported by the boss 43a of the sun gear 43 via a bearing. The boss portion 47a of the ring gear 47 is rotatably supported by the planetary gear case 41 via a bearing, and is rotatably supported by the boss portion 43a of the sun gear 43 via a bearing.
The support shaft 45 of each planetary gear 44 is supported by the carrier 46 in a cantilever state connected to the carrier 46 only at one end. The three support shafts 45 are connected by one annular support plate, and the meshing state of the planetary gear 44 with the sun gear 43 and the ring gear 47 is maintained.

  A planetary gear case 41 rotatably supports a cylindrical input rotator 42. The input rotator 42 is integrally and rotatably linked to the motor shaft 25 by a spline fitting structure. The input rotator 42 and the sun gear 43 mesh with a transmission gear 42a provided integrally rotatably on the outer peripheral surface of the input rotator 42 and a passive gear 43b provided integrally rotatable on the outer peripheral portion of the boss 43a of the sun gear 43. Are linked by

  The ring gear 47 is integrally rotatably linked to the output shaft 48 by a spline fitting structure provided over the boss 47a and the output shaft 48.

A cylindrical shaft-shaped input rotating body 49 is rotatably supported by the planetary gear case 41. The input rotating body 49 is integrally and rotatably linked to the pump shaft 22 by a spline fitting structure.
The input rotator 49 and the carrier 46 are interlocked by meshing between a transmission gear 49a provided integrally rotatably on the outer peripheral surface side of the input rotator 49 and a passive gear 46a provided integrally rotatable on the outer peripheral portion of the carrier 46. I have.

  That is, the planetary gear mechanism 40 inputs the power output from the output shaft 55 by the forward / reverse switching mechanism 50 to the input rotating body 49 via the pump shaft 22, thereby eliminating the power from the forward / reverse switching mechanism 50. The power is input to the carrier 46 without being subjected to the shifting operation by the stepless transmission mechanism 20, and the power output from the motor shaft 25 by the stepless transmission mechanism 20 is input to the sun gear 43, and the power from the stepless transmission mechanism 20 is continuously input to the sun gear 43. The power from the forward / reverse switching mechanism 50 that is not subjected to the shifting action of the transmission mechanism 20 is combined, and the combined power is output from the output shaft 48 to the auxiliary transmission mechanism 60.

  The auxiliary transmission mechanism 60 includes an input shaft 61 integrally formed with the output shaft 48 of the planetary gear mechanism 40, a first gear 62 a and a second gear 63 a that are integrally rotatably provided on the input shaft 61, and a first gear 62 a A third gear 62b rotatably provided on the output shaft 64 while meshing with the fourth gear 63b rotatably provided on the output shaft 64 while meshing with the second gear 63a. A first transmission clutch 65 that is provided so as to be rotatable integrally and is connectable to the third gear 62b or the fourth gear 63b, a fifth gear 66b that rotates integrally with the fourth gear 63b, and a state meshed with the fifth gear 66b. A sixth gear 66a provided rotatably with the transmission shaft 67, a seventh gear 69a connectable via the transmission shaft 67 and the second transmission clutch 68, and an output shaft 64 meshed with the seventh gear 69a. In one And a eighth gear 69b provided rolling freely.

When the first transmission clutch 65 is connected to the third gear 62b and the second transmission clutch 68 is disconnected from the seventh gear 69a by the shift operation, the power transmitted from the planetary gear mechanism 40 to the input shaft 61. Is transmitted to the output shaft 64 at a high speed via the first gear 62a, the third gear 62b, and the first transmission clutch 65.
When the first transmission clutch 65 is connected to the fourth gear 63b and the second transmission clutch 68 is disconnected from the seventh gear 69a by the shift operation, the power transmitted from the planetary gear mechanism 40 to the input shaft 61 is released. Is transmitted to the output shaft 64 at a low speed via the second gear 63a, the fourth gear 63b, and the first transmission clutch 65.
When the first transmission clutch 65 is disconnected from the third gear 62b and the fourth gear 63b by the shift operation and the second transmission clutch 68 is connected to the seventh gear 69a, the input shaft 61 from the planetary gear mechanism 40. Transmitted through the second gear 63a, the fourth gear 63b, the fifth gear 66b, the sixth gear 66a, the transmission shaft 67, the second transmission clutch 68, the seventh gear 69a, and the eighth gear 69b. It is transmitted to the shaft 64 at a medium speed.

The rear wheel drive shaft 32 is integrally rotatably linked to the output shaft 64 of the auxiliary transmission mechanism 60 by a spline fitting structure.
The power output from the output shaft 64 is transmitted from the rear wheel drive shaft 32 to the rear wheel 2 via the rear wheel differential mechanism 33.
The power output from the output shaft 64 is transmitted to a front wheel drive shaft 35 interlocked with the rear wheel drive shaft 32 via a gear interlocking mechanism 34 and transmitted to a front wheel speed change drive shaft 37 via a front wheel speed change mechanism 36. The transmission is transmitted from the front wheel transmission drive shaft 37 to the front wheels 1 via the front wheel differential mechanism 38.

  The traveling system transmission D1 switches the output of the engine 3a to forward power and reverse drive by the forward / reverse switching mechanism 50, and continuously changes the forward power and reverse power output by the forward / reverse switching mechanism 50 by the planetary gear mechanism 40. The output from the output shaft 48 is shifted to a plurality of low, middle, and high speed stages by the subtransmission mechanism 60, and the forward power and the reverse power that the subtransmission mechanism 60 shifts are transmitted from the output shaft 64 of the subtransmission mechanism 60. Power is transmitted via the rear wheel differential mechanism 33 to drive the rear wheel 2 and transmitted from the output shaft 64 of the auxiliary transmission mechanism 60 via the gear interlocking mechanism 34, the front wheel transmission mechanism 36, and the front wheel differential mechanism 38. Then, the front wheels 1 are driven.

  As shown in FIG. 4, the output shaft 3b of the engine 3a, the input shaft 51 of the forward / reverse switching mechanism 50, the sun gear 43, the carrier 46 and the output shaft 48 of the planetary gear mechanism 40, the input shaft 61 of the auxiliary transmission mechanism 60, the work clutch The input-side power transmission shaft 72a and output-side power transmission shaft 72b of 70 and the power transmission shaft 73 of the work transmission mechanism 71 have their respective rotation axes disposed on the same first axis P1.

Generally, in order to transmit power from one of two parallel rotating shafts to the other, gears provided on both rotating shafts are engaged with each other, or a chain or a transmission belt is provided between sprockets provided on both rotating shafts. Or the like, which requires a large space. In addition, the transmission efficiency decreases as the gears and the like are interposed.
As described above, the input shaft 51 of the forward / reverse switching mechanism 50, the sun gear 43, the carrier 46, and the output shaft 48 of the planetary gear mechanism 40, the input shaft 61 of the subtransmission mechanism 60, the input power transmission shaft 72a of the work clutch 70, and the output. By arranging the rotation axes of the side power transmission shaft 72b and the power transmission shaft 73 of the work transmission mechanism 71 on the same first axis P1 as the rotation axis of the output shaft 3b of the engine 3a, space can be saved. And the transmission efficiency is prevented from decreasing.

  The power output shaft 7 to which power is transmitted from the output shaft 64 of the auxiliary transmission mechanism 60, the rear wheel differential mechanism 33, the brake shaft or rear wheel shaft 31 of the rear wheel 2, and the power transmission shaft 73 via gears 74 and 75. Are arranged such that each rotation axis is on the same second axis P2. The height of the second axis P2 is located at a position lower than the first axis P1.

  The pump shaft 22 and the motor shaft 25 have a third shaft center P3 coinciding with the rotation axis of the pump shaft 22 and a fourth shaft center P4 coincident with the rotation axis of the motor shaft 25, the height of which is the first shaft P4. At a position lower than the center P1 and a position higher than the second axis P2, they are arranged left and right with respect to the first axis P1 in a vehicle front view. Note that the third axis P3 is disposed on the left with respect to the first axis P1, the fourth axis P4 is disposed on the right with respect to the first axis P1, and the third axis P3 is a twist of P4. It is located slightly higher.

  The continuously variable transmission mechanism 20 has at least a hydraulic circuit disposed between the hydraulic pump 20P and the hydraulic motor 20M, and a mechanism such as the hydraulic cylinder for driving the swash plate 27 of the hydraulic pump 20P. Installation space is required. If the continuously variable transmission mechanism 20 is disposed close to one of the left and right of the first axis P1 in a front view of the tractor, the body frame 5 on the side where the continuously variable transmission mechanism is disposed may be strengthened. Therefore, it is necessary to increase the vehicle width.

  By arranging the hydraulic pump 20P and the hydraulic motor 20M on the left and right sides with respect to the rotation axis of the output shaft 3b of the engine 3a in a front view of the tractor, particularly, the third axis P3 and the fourth axis P4 are arranged. Are disposed on the left and right sides of the first axis P1 in the front view of the tractor, so that the left and right unevenness of the vehicle body frame 5 and the left and right unevenness of the vehicle width need not be increased. .

  The output shaft 55 of the forward / reverse switching mechanism 50 is coaxial with the third shaft center P3 because the output shaft 55 is integrally and rotatably connected to the pump shaft 22 by a spline fitting structure. The transmission shaft 67 of the subtransmission mechanism 60 is not directly connected to the pump shaft 22, but is disposed behind the pump shaft 22 on the substantially same axis as the third axis P3.

  The fifth axis P5 coinciding with each rotation axis of the front wheel drive shaft 35 and the clutch of the front wheel transmission mechanism 36 is at a position lower than the second axis P2 with respect to the second axis P2 in the front view of the vehicle body. It is arranged slightly to the left and to the right of the third axis P3. A sixth axis P6 coinciding with each rotation axis of the front wheel speed change drive shaft 37 and the front wheel differential mechanism 38 is lower than the fifth axis P5, and is located at a position lower than the second axis P2 in the vehicle body front view. It is arranged slightly to the left and to the right of the fifth axis P5.

  The lubricating oil level is set to the same height as the second shaft center P2, and the output shaft 3b of the engine 3a, the forward / reverse switching mechanism 50, the planetary gear mechanism 40, a part of the auxiliary transmission mechanism 60, the work clutch 70, the work The transmission mechanism 71 and the hydraulic pump 20P are provided above the oil level.

A part of the auxiliary transmission mechanism 60, the brake shaft or rear wheel shaft 31 of the rear wheel 2, and the power take-out shaft 7 are arranged at the level of the oil level.
The front wheel drive shaft 35, the clutch of the front wheel transmission mechanism 36, the front wheel transmission drive shaft 37, the front wheel differential mechanism 38, and the brake shaft or front wheel shaft 39 of the front wheel 1 are disposed below the oil level. I have.

  By arranging structurally large mechanisms such as the forward / reverse switching mechanism 50 and the planetary gear mechanism 40 above the oil level, the power of the gears provided by the forward / backward switching mechanism 50 and the planetary gear mechanism 40 is reduced. Transmission loss and unnecessary heat generation due to agitation of the lubricating oil by the gears can be eliminated.

  On the other hand, since the brake shaft or the front wheel shaft 39 of the front wheel 1 and the brake shaft or the rear wheel shaft 31 of the rear wheel 2 are always in contact with the lubricating oil, the frictional heat generated by the brake is quickly cooled.

  In the transmission D configured as described above, the tractor engine 3a is started with the forward clutch 52 and the reverse clutch 56 of the forward / reverse switching mechanism 50 and the work clutch 70 disengaged. That is, the start of the engine 3a of the tractor can be performed in a state where the traction engine is not connected to the traveling system transmission device D1 or the work system transmission device D2. Therefore, an increase in the size of the starter can be avoided by reducing the load torque at the time of starting the engine 3a.

  Preventing the tractor from becoming wider by arranging the mechanisms constituting the traveling transmission D1 and the working transmission D2 such that the overall width of the transmission D is narrower when viewed from the front of the vehicle. Can be.

  By setting the shape of the clutch housing 10 and the front transmission case 11a of the transmission D to a shape that can be connected to the engine 3a and the rear transmission case 11b of the existing tractor, the transmission D according to the present invention can be applied to the existing tractor. Can be easily incorporated.

  The transmission according to the present invention can be used for a tractor in which a working device such as a mowing device is connected between front and rear wheels of a vehicle body or in front of a vehicle body, in addition to a tractor having a working device connected to a rear portion of the vehicle body.

3a engine 3b output shaft (engine output section)
7 Power take-out shaft (power take-out part)
Reference Signs List 20 continuously variable transmission mechanism 20M hydraulic motor 20P hydraulic pump 22 pump shaft (continuously variable transmission mechanism input section)
25 Motor shaft (stepless transmission mechanism output unit)
31 Rear wheel shaft (rear wheel drive unit)
32 rear wheel drive shaft (rear wheel drive unit, rear wheel drive unit input unit)
33 Rear wheel differential mechanism (rear wheel drive unit)
40 planetary gear mechanism 43 sun gear (planetary gear mechanism first input section)
46 Carrier (planetary gear mechanism second input unit)
48 Output shaft (planetary gear mechanism output section)
50 forward / backward switching mechanism 51 input shaft (forward / backward switching mechanism input section)
55 Output shaft (forward / backward switching mechanism output unit)
61 input shaft 64 output shaft 67 transmission shaft 70 work clutch 72a input-side power transmission shaft (work clutch input section)
72b output side power transmission shaft (work clutch output section)
D transmission device D1 traveling system transmission device D2 work system transmission device P1 first axis P2 second axis P3 third axis P4 fourth axis

Claims (1)

A transmission device that is provided in the tractor and transmits power output by the engine to the traveling device and the working device,
Reverse switching mechanism, hydrostatic type continuously variable transmission mechanism, a planetary gear mechanism, comprising a rear wheel drive and work clutch,
The forward-reverse switching mechanism includes a forward-reverse switching mechanism input unit to which power output from an engine output unit of the engine is input, and a forward or reverse rotation of the power input to the forward-reverse switching mechanism input unit. A forward / reverse switching mechanism output section for switching and outputting,
The continuously variable transmission mechanism continuously varies the power input to the continuously variable transmission mechanism input section to which the power output from the forward / reverse switching mechanism output section is input, and outputs the power supplied to the continuously variable transmission mechanism input section. Having a continuously variable transmission mechanism output section,
The planetary gear mechanism includes a planetary gear mechanism first input unit to which the power output from the continuously variable transmission mechanism output unit is input, and a power output from the forward / reverse switching mechanism output unit, wherein the power is output from the continuously variable transmission mechanism. The planetary gear mechanism second input unit that is input without stepless speed change, and the power input to the planetary gear mechanism first input unit and the planetary gear mechanism second input unit are combined, and the combined power is A planetary gear mechanism output unit for outputting,
The rear wheel drive unit has a rear wheel drive unit input unit to which the power output from the planetary gear mechanism output unit is input,
The work clutch has a work clutch input unit to which the power output from the engine output unit is input, and a work clutch output unit that can output the power input to the work clutch input unit,
The continuously variable transmission mechanism is disposed rearward of the forward / reverse switching mechanism and forward of the planetary gear mechanism,
The first shaft center having the same rotation axis as the forward / reverse switching mechanism input section, the planetary gear mechanism first input section, the planetary gear mechanism second input section, the planetary gear mechanism output section and the work clutch input section. Arranged above,
In a front view of the tractor, the rotation axis of the continuously variable transmission mechanism is disposed on one side in the left-right direction with respect to the first axis, and the rotation axis of the continuously variable transmission mechanism is connected to the first axis. A transmission device, which is disposed on the other side in the left-right direction with respect to the shaft center .

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