JP2020037985A - Transmission device for travel of tractor, and tractor including transmission device for travel of tractor - Google Patents

Abstract

To increase a reduction gear ratio in the entire creep transmission while suppressing increase in size of a transmission case, in a transmission device for travel of a tractor in which a creep transmission device is housed in the transmission case.SOLUTION: A creep transmission device 60 is provided with a first transmission gear 66 disposed on an output shaft gear 54b of a gear transmission 40, a first reduction gear 62 relatively rotatably supported by a relay shaft 61 in a state of being engaged with the first transmission gear 66, a second transmission gear 67 disposed on the first reduction gear 62, a second reduction gear 63 relatively rotatably supported by an output shaft 43 of the gear transmission 40 in a state of being engaged with the second transmission gear 67, a third transmission gear 68 disposed on the second reduction gear 63, a third reduction gear 64 not relatively rotatably supported by the relay shaft 61 in a state of being engaged with the third transmission gear 68, and a reduction gear pair 65 disposed over the relay shaft 61 and the output shaft 43 to decelerate power of the relay shaft 61 to transmit the same to the output shaft 43.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a tractor traveling transmission and a tractor including the tractor traveling transmission.

  As a tractor traveling transmission, a gear transmission that receives the power of the engine and shifts and outputs the input power, and a gear transmission that receives the output of the gear transmission and reduces the input power to reduce the difference between the rear wheels Some are provided with a creep transmission that outputs to a moving mechanism, and a transmission case that houses the gear transmission and the creep transmission.

  As a creep transmission in this type of tractor traveling transmission, for example, there is one disclosed in Patent Document 1. In the creep transmission disclosed in Patent Document 1, a creep input gear provided integrally with the third low-speed gear of the auxiliary transmission, a reduction gear meshing with the creep input gear, a creep output gear provided side by side with the reduction gear, A creep gear that meshes with the creep output gear is provided. That is, the power of the third low speed gear is reduced between the creep input gear and the reduction gear, and the reduced power is reduced between the creep output gear and the creep gear and input to the rear wheel differential device from the transmission shaft. Is done.

JP-A-10-6792

  In the conventional case, since the creep shift is performed by two gear pairs, it is necessary to employ a gear having a large gear diameter to increase the reduction ratio of the entire crepe shift, so that the transmission case becomes large.

  The present invention provides a tractor traveling transmission device and a tractor capable of increasing the reduction ratio of the entire creep shift while suppressing an increase in the size of the transmission case.

The traveling transmission for a tractor according to the present invention comprises:
A gear transmission to which the power of the engine is input, and to shift and output the input power; and a creep shift to which the output of the gear transmission is input, to reduce the input power and output to the differential mechanism for the rear wheels. And a transmission case that houses the gear transmission and the creep transmission. The gear transmission further includes an output shaft that transmits power to the differential mechanism, and an output shaft that is supported by the output shaft and outputs the power. An output shaft that can be switched between a transmission-engaged state in which the shaft is relatively non-rotatably engaged to transmit power to the output shaft and a transmission-off state in which engagement with the output shaft is released and power transmission to the output shaft is cut off. A gear, a relay shaft parallel to the output shaft, and the output shaft gear are provided in the creep transmission so as to be relatively non-rotatable. A first transmission gear, a first reduction gear that is rotatably supported by the relay shaft while being engaged with the first transmission gear, and that rotates at a lower speed than the first transmission gear; A second transmission gear provided on the reduction gear so as to be relatively non-rotatable; and a second transmission gear rotatably supported by the output shaft while being engaged with the second transmission gear, and rotating at a lower speed than the second transmission gear. A second reduction gear, a third transmission gear provided to the second reduction gear so as to be relatively non-rotatable, and supported by the relay shaft so as to be relatively non-rotatable while being engaged with the third transmission gear; and A third reduction gear that rotates at a lower speed than the third transmission gear, and a transmission-engaged state that is provided across the relay shaft and the output shaft and that reduces the power of the relay shaft and transmits the power to the output shaft. And power transmission to cut off power transmission to the output shaft A reduction gear pair capable switched on purpose, is provided.

  According to this configuration, the power of the output shaft gear is transmitted between the first transmission gear and the first reduction gear, the second transmission gear and the second reduction gear, and the third transmission gear and the third reduction gear. Since a total of four gear pairs, a gear pair and a reduction gear pair, perform the creep shift as the entire creep shift, that is, the creep shift is performed by a larger number of gear pairs than in the related art, so that each gear pair has a gear diameter. Even if a gear smaller than the conventional gear is adopted, the creep shift can be performed at the same reduction ratio as the conventional one or at a higher reduction ratio than the conventional one. Since the output shaft is used as a support shaft of the second reduction gear, there is no need to provide a special support shaft for the second reduction gear.

  Accordingly, it is possible to increase the reduction ratio of the entire crepe shift so that the vehicle can run at an extremely low speed while suppressing an increase in the size of the transmission case.

  In the present invention, it is preferable that in the direction along the axis of the relay shaft, the reduction gear pair is located on a side opposite to a side where the first reduction gear is located with respect to the output shaft gear. .

  According to this configuration, the space in the transmission case on the side where the one end of the relay shaft is located relative to the output shaft gear and the space in the transmission case where the other end of the relay shaft is located relative to the output shaft gear are reduced. Since the gear pair and the first reduction gear can be disposed separately, the empty space in the transmission case can be easily used for the installation space of the creep transmission, and the size of the transmission case can be suppressed.

In the present invention, the relay shaft is provided below the output shaft,
Preferably, a clutch for switching the reduction gear pair between the transmission-on state and the transmission-off state is provided over the transmission gear of the reduction gear pair that is supported by the relay shaft and the relay shaft. It is.

  According to this configuration, the clutch can be arranged at the bottom of the transmission case in the space inside the transmission case, so that it is easy to obtain a compact operation structure for operating the clutch from outside the transmission case.

  In the present invention, the power of the engine is input, a clutch unit that converts the input power into forward power and reverse power is provided, and a forward output unit that outputs the converted forward power is converted. A forward / reverse switching device separately having a reverse output unit for outputting reverse power, and a rotary transmission that is provided across the reverse output unit and the input unit of the gear transmission, and transmits the power of the reverse output unit to the input unit. A high-speed transmission state in which the power of the forward output unit is shifted to a high-speed side and transmitted to the rotary transmission shaft, and the power of the forward output unit is provided on the low-speed side. And a high-low speed switching device capable of switching to a low-speed transmission state in which the transmission speed is transmitted to the rotary transmission shaft.

  According to this configuration, the reverse power output by the forward / reverse switching device is input to the gear transmission without being subjected to the shifting action by the high / low speed switching device, and the forward power output by the forward / reverse switching device is transmitted to the high speed side by the high / low speed switching device. Since it is input to the gear transmission in a state shifted to the low speed side, it is possible to switch between forward traveling and reverse traveling simply by switching the forward / reverse switching device while enabling speed change when traveling forward. The transmission structure can be obtained simply.

  In the present invention, it is preferable that the rotation transmission shaft and the input unit are provided concentrically and in a straight line.

  According to this configuration, since the rotary transmission shaft and the input unit are located in a positional relationship that facilitates connection, the rotary transmission shaft and the input unit can be interlocked and connected by the simple connecting means.

  In the present invention, it is preferable that the reverse output portion is provided on the front side of the clutch portion, and the forward output portion is provided on the rear side of the clutch portion.

  According to this configuration, since the reverse output portion and the forward output portion do not overlap, a forward / reverse switching device can be obtained with a simple structure.

Another tractor travel transmission according to the invention is:
Engine power is input, the input power is converted into forward power and reverse power, and a forward output section that outputs the converted forward power and a reverse output section that outputs the converted reverse power are separately provided. A forward / backward switching device, a gear transmission having an input portion to which power is input, shifting the power input to the input portion and outputting the power to the traveling device, and the reverse output portion and the input portion. A rotation transmission shaft that transmits the power of the reverse output unit to the input unit, and is provided over the forward output unit and the rotation transmission shaft, and outputs the power output by the forward output unit on the high-speed side and the low-speed side. And a high-low speed switching device for outputting the shifted high-speed power and the shifted low-speed power to the rotary transmission shaft.

  According to this configuration, the reverse power output by the forward / reverse switching device is input to the gear transmission without being subjected to the shifting action by the high / low speed switching device, and the forward power output by the forward / reverse switching device is transmitted to the high speed side by the high / low speed switching device. Since it is input to the gear transmission in a state shifted to the low speed side, it is possible to switch between forward traveling and reverse traveling simply by switching the forward / reverse switching device while enabling speed change when traveling forward. The transmission structure can be obtained simply.

  The transmission for traveling a tractor according to the present invention is applicable to a tractor.

  ADVANTAGE OF THE INVENTION According to the tractor provided with the driving | running | working transmission of the tractor by this invention, the tractor which can drive at an extremely low speed and can work easily can be obtained, suppressing enlargement of a tractor.

It is a left view which shows the whole tractor. It is sectional drawing in an expanded state which shows the transmission for driving | running | working. It is a longitudinal side view which shows a forward / reverse switching device and a high-low speed switching device. FIG. 2 is a vertical sectional side view showing a gear transmission and a creep transmission. FIG. 3 is a rear view showing an arrangement of an input shaft, a transmission relay shaft, an output shaft, a relay shaft, and a front wheel transmission shaft. It is sectional drawing in an expanded state which shows the transmission for driving provided with another implementation structure.

Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.
In the following description, regarding the body of the tractor, the direction of arrow F shown in FIG. 1 is “front of the vehicle body”, the direction of arrow B is “back of the vehicle body”, the direction of arrow U is “upper body”, and the direction of arrow D is The direction is "downward of the vehicle body", the direction of the front side of the paper is "left of the vehicle", and the direction of the rear side of the paper is "right of the vehicle".

  As shown in FIG. 1, the tractor is equipped with a pair of left and right front wheels 1 as a traveling device so as to be drivable and swingably steerable, and a pair of left and right rear wheels 2 as a traveling device is drivable. It has an equipped body. A driving portion 4 having an engine 3 is formed at a front portion of the vehicle body. A driver 7 having a driver seat 5 and a steering wheel 6 for steering the front wheels 1 is formed at the rear of the vehicle body. At the rear of the body frame 8, a link mechanism 9 for connecting various working devices so as to be able to move up and down is provided. The vehicle body frame 8 includes an engine 3, a clutch housing 10 connected to a rear portion of the engine 3, a transmission case 11 having a front portion connected to the clutch housing 10, and a front wheel support frame 12 extending forward from the engine 3. And is constituted by.

  In the tractor, a plow (not shown) and a rotary tilling device (not shown) are connected to a rear portion of the vehicle body via a link mechanism 9 to constitute a riding cultivator. A front loader device (not shown) is connected to a front part of the vehicle body to constitute a loader working machine. As described above, various working machines are connected to the vehicle body to form various working machines. A power take-out shaft 13 that outputs power of the engine 3 to a connected working device is provided at a rear portion of the transmission case 11.

[About the configuration of the traveling transmission]
A traveling transmission 14 for transmitting the power of the engine 3 to the front wheels 1 and the rear wheels 2 is configured as shown in FIG. The traveling transmission device 14 includes the transmission case 11. In the traveling transmission device 14, the transmission case 11 is set so that the front-rear direction coincides with the vehicle front-rear direction, and the up-down direction of the transmission case 11 coincides with the up-down direction of the vehicle body.

  As shown in FIG. 2, a forward / reverse switching device 20 that converts the power of the engine 3 (see FIG. 1) into forward power and reverse power, and two stages of high / low speed forward power output by the forward / backward switching device 20 Gear transmission 40 to which the reverse power output by the forward / reverse switching device 20 and the forward power output by the high / low speed switching device 30 and the power output by the gear transmission 40 are output. A creep transmission 60 that shifts, a rear wheel differential mechanism 70 that transmits the power output by the gear transmission 40 and the power output by the creep transmission 60 to the left and right rear wheels 2, and a power output by the gear transmission 40. And a front wheel transmission shaft 44 that outputs the power output by the creep transmission 60 to the left and right front wheels 1 (see FIG. 1). It has been furnished to the Deployment case 11.

  The gear transmission 40 and the creep transmission 60 are provided behind the forward / reverse switching device 20 and the high / low speed switching device 30. The rear wheel differential mechanism 70 is provided on the rear side of the gear transmission 40 and the creep transmission 60.

  As shown in FIG. 2, the transmission case 11 includes a front split transmission case 11A that houses a forward / reverse switching device 20, a high / low speed switching device 30, a gear transmission 40, a creep transmission 60, and a front wheel transmission shaft 44, and a rear split transmission case 11A. And a rear split transmission case 11B that accommodates the differential mechanism 70 for wheels. A power take-out case 71 that supports the power take-out shaft 13 is detachably connected to a rear portion of the rear split transmission case 11B. The power take-out case 71 houses a work transmission 72 that changes the power from the engine 3 (see FIG. 1) and transmits the power to the power take-out shaft 13. The power of the engine 3 is input to the work transmission 72 via a rotation shaft 73, a work clutch 74 and a rotation shaft 75. Reference numeral 76 shown in FIG. 2 is a hydraulic pump driven by taking in power from the rotating shaft 73.

[Configuration of forward / backward switching device]
As shown in FIGS. 2 and 3, the forward / reverse switching device 20 has an input shaft 21 to which the power of the engine 3 (see FIG. 1) is input via the main clutch 15, and is mounted on the input shaft 21. A clutch unit 22 for converting the power input to the shaft 21 into forward power and reverse power, a forward output gear 23 as a forward output unit for outputting the converted forward power, and a reverse for outputting the converted reverse power And a reverse output gear 24 as an output unit.

  In the present embodiment, the reverse output gear 24 is provided on the front side of the clutch unit 22, and the forward output gear 23 is provided on the rear side of the clutch unit 22. However, the invention is not limited thereto, and the reverse output gear 24 may be provided on the rear side of the clutch unit 22, and the forward output gear 23 may be provided on the front side of the clutch unit 22.

  As shown in FIGS. 2 and 3, the clutch portion 22 includes a forward clutch 22F and a reverse clutch 22R mounted on the input shaft 21. The forward clutch 22F is provided on the rear side of the reverse clutch 22R. The reverse gear 26 is engaged with the output member 25 of the reverse clutch 22 </ b> R and the reverse output gear 24. The reverse output gear 24 is operatively connected to an output member 25 via a reverse rotation gear 26. The forward output gear 23 is operatively connected to the output member 27 of the forward clutch 22F. The forward output gear 23 and the output side member 27 are linked and connected by integrally forming the forward output gear 23 and the output side member 27.

  In the present embodiment, the forward clutch 22F and the reverse clutch 22R are configured by hydraulically controlled wet multiple disc clutches, but are not limited thereto. As the forward clutch 22F and the reverse clutch 22R, a dry multi-plate clutch, a single-plate clutch, a dog clutch, or the like can be used.

  In the forward / reverse switching device 20, when the forward clutch 22F is operated to be engaged, the power of the input shaft 21 is transmitted to the forward output gear 23 by the forward clutch 22F and output from the forward output gear 23. When the vehicle is in the forward transmission state and the reverse clutch 22R is operated to be engaged, the power of the input shaft 21 is transmitted to the reverse gear 26 by the reverse clutch 22R, transmitted from the reverse gear 26 to the reverse output gear 24, and travels backward. The vehicle is in the reverse transmission state so as to be output from the output gear 24.

  A rotary transmission shaft 28 is provided to extend between the reverse output gear 24 and the input shaft 41 as an input portion of the gear transmission 40 and to link the reverse output gear 24 and the input shaft 41 in an interlocked manner. A high / low speed switching device 30 is provided over the forward output gear 23 and the rotary transmission shaft 28.

  In the forward / reverse switching device 20, when operated in the forward transmission state, the clutch portion 22 transmits the power of the input shaft 21 to the forward output gear 23 and is converted into forward power by the forward output gear 23, and the converted forward power is transmitted. Power is input from the forward output gear 23 to the high / low speed switching device 30.

  In the forward / reverse switching device 20, when operated in the reverse transmission state, the clutch unit 22 transmits the power of the input shaft 21 to the reverse gear 26, and converts the power to reverse power by the reverse gear 26 and the reverse output gear 24. The reverse power is transmitted from the reverse output gear 24 to the rotary transmission shaft 28. The reverse power output by the forward / reverse switching device 20 is input to the gear transmission 40 by the rotary transmission shaft 28. The reverse power output by the forward / reverse switching device 20 is input to the gear transmission 40 without being shifted.

[Configuration of high / low speed switching device]
As shown in FIGS. 2 and 3, the high / low speed switching device 30 is provided across the forward output gear 23 and the rotary transmission shaft 28, and shifts the power of the forward output gear 23 to power having two different rotational speeds. The power is transmitted to the rotation transmission shaft 28.

  Specifically, as shown in FIGS. 2 and 3, the high / low speed switching device 30 includes a high speed side gear pair 31 provided over the forward output gear 23 and the rotary transmission shaft 28, and a forward output gear 23. And a low-speed side gear pair 32 provided at a low speed and provided over the rotary transmission shaft 28. The high-speed side gear pair 31 is configured such that the rotary transmission shaft is engaged with the large-diameter gear portion 23a of the pair of gear portions 23a and 23b formed on the forward output gear 23 and the large-diameter gear portion 23a. And a high-speed setting gear 31a rotatably supported by the motor 28. The low-speed side gear pair 32 is relatively rotatable with the rotary transmission shaft 28 in a state of being engaged with the small-diameter side gear portion 23b of the pair of gear portions 23a and 23b of the forward output gear 23 and the small-diameter side gear portion 23b. And a low-speed setting gear 32a supported by the gears.

  A high-speed side clutch 33 is provided between the high-speed setting gear 31a and the rotary transmission shaft 28. A low-speed clutch 34 is provided between the low-speed setting gear 32a and the rotary transmission shaft 28. In the present embodiment, the high-speed side clutch 33 and the low-speed side clutch 34 are constituted by hydraulically controlled wet multiple disc clutches, but are not limited thereto. As the high-speed side clutch 33 and the low-speed side clutch 34, a dry multi-plate clutch, a single-plate clutch, a dog clutch or the like can be employed.

  In the high-low speed switching device 30, the high-speed side clutch 33 is operated to be in the ON state, and the low-speed side clutch 34 is operated to be in the OFF state, whereby the high-speed transmission state is established, and the high-speed side clutch 33 is operated to be in the OFF state. When the low-speed side clutch 34 is operated to be engaged, a low-speed transmission state is established.

  In the high / low speed switching device 30, when operated in the high speed transmission state, the forward power of the forward output gear 23 is shifted to the high speed side by the high speed side gear pair 31, and transmitted to the rotary transmission shaft 28 by the high speed side clutch 33, The rotation is transmitted to the gear transmission 40 by the rotation transmission shaft 28.

  In the high / low speed switching device 30, when operated in the low speed transmission state, the forward power of the forward output gear 23 is shifted to the low speed side by the low speed side gear pair 32 and transmitted to the rotary transmission shaft 28 by the low speed side clutch 34, The rotation is transmitted to the gear transmission 40 by the rotation transmission shaft 28.

  The rotational speed of the forward power when the high / low speed switching device 30 is operated in the high speed transmission state and the forward power is input to the gear transmission 40, and the forward / reverse switching device 20 is operated in the reverse transmission state to move the gear transmission 40 backward. The rotational speed of the reverse power when power is input is set to the same speed.

[Configuration of gear transmission]
As shown in FIG. 4, the gear transmission 40 includes a main transmission unit 40A that shifts the power input by the rotary transmission shaft 28 from six speeds of a first speed to a sixth speed, and a main transmission unit 40A. And a sub-transmission portion 40 </ b> B that transmits the output power to a two-stage high-low speed transmission power and transmits the power to the rear wheel differential mechanism 70 and the front wheel transmission shaft 44.

  Specifically, as shown in FIGS. 2 and 4, the gear transmission 40 includes an input shaft 41 serving as an input portion interlocked and connected to the rotary transmission shaft 28, and a cylinder provided in parallel with the input shaft 41. An axial transmission relay shaft 42, an output shaft 43 provided parallel to the transmission relay shaft 42, and a front wheel transmission shaft 44 provided parallel to the output shaft 43 are provided. The rotation transmission shaft 28 and the input shaft 41 are provided in a state of being located concentrically and in a state of being aligned in a straight line. The rotary transmission shaft 28 and the input shaft 41 are interlockingly connected by a front portion of the input shaft 41 being externally fitted and engaged with a spline shaft portion provided at a rear portion of the rotary transmission shaft 28. The transmission relay shaft 42 is fitted around the rotation shaft 73 so as to be relatively rotatable. The center line C shown in FIG. 5 indicates the center of the vehicle body in the left-right direction. As shown in FIG. 5, the transmission relay shaft 42 and the output shaft 43 are provided at the center of the vehicle body in the left-right direction. The transmission relay shaft 42 is provided above the output shaft 43. The input shaft 41 is provided laterally outside the vehicle body with respect to the transmission relay shaft 42 and the output shaft 43. The input shaft 41 is provided above the output shaft 43. The front wheel transmission shaft 44 is provided outside the vehicle body opposite to the side where the input shaft 41 is located with respect to the transmission relay shaft 42 and the output shaft 43. The front wheel transmission shaft 44 is provided below the output shaft 43.

  As shown in FIG. 4, the main transmission portion 40A is provided across the input shaft 41 and the transmission relay shaft 42, and converts the power of the input shaft 41 into power having different rotational speeds in six stages from the first speed to the sixth speed. The transmission speed is transmitted to the transmission relay shaft 42.

  Specifically, as shown in FIG. 4, the main transmission unit 40 </ b> A is connected to a first speed gear pair 45 provided between the input shaft 41 and the transmission relay shaft 42 to a sixth speed gear pair 50 and the input shaft 41. The first shift gear 52a, the second shift gear 52b, and the third shift gear 52c are supported so as to be non-rotatable and slidable. Each of the first gear pair 45 to the sixth gear pair 50 has input shaft gears 45a to 50a rotatably supported on the input shaft 41, and has a second gear on the side of the input shaft gears 45a to 50a. When the first shift gear 52a, the second shift gear 52b, or the third shift gear 52c is engaged and the input shaft gears 45a to 50a are interlocked to the input shaft 41 by the first shift gear 52a, the second shift gear 52b, or the third shift gear 52c, A shift operation state is established in which the power of the input shaft 41 is shifted and transmitted to the transmission relay shaft 42. In each of the first gear pair 45 to the sixth gear pair 50, the engagement of the first shift gear 52a or the second shift gear 52b or the third shift gear 52c with the input shaft gears 45a to 50a is released, and the input shaft gears 45a to 50c are disengaged. When the interlocking connection of the input shaft 41 to the input shaft 41 is released, the transmission is released.

  As shown in FIG. 4, the auxiliary transmission portion 40B is provided across the transmission relay shaft 42 and the output shaft 43, and outputs the power of the transmission transmission shaft 42 by changing the power of the transmission relay shaft 42 to two different levels of high and low rotational speeds. The power is transmitted to the shaft 43 and transmitted from the output shaft 43 to the rear wheel differential mechanism 70 and the front wheel transmission shaft 44.

  Specifically, as shown in FIG. 4, the auxiliary transmission portion 40 </ b> B is provided between the transmission relay shaft 42 and the output shaft 43, and is provided between the transmission relay shaft 42 and the output shaft 43. And a fourth shift gear 55 slidably and non-rotatably supported on the output shaft 43.

  The high-speed setting gear pair 53 is rotatably supported by the output shaft 43 in a state in which the high-speed setting relay shaft gear 53a is supported by the mission relay shaft 42 so as to be relatively non-rotatable, and is engaged with the high-speed setting relay shaft gear 53a. And a high-speed output shaft gear 53b. The high-speed relay shaft gear 53a is supported by the transmission relay shaft 42 so as not to rotate relatively, and is constituted by a relay shaft gear constituting the third speed gear pair 47 of the main transmission unit 40A.

  The low-speed setting gear pair 54 is rotatably supported by the output shaft 43 in a state in which the low-speed setting relay shaft gear 54a is supported by the transmission relay shaft 42 so as not to rotate relatively, and the low-speed setting relay shaft gear 54a is engaged with the low-speed setting relay shaft gear 54a. Output shaft gear 54b set at a low speed.

  In the subtransmission 40B, when the fourth shift gear 55 is engaged with the side portion of the output shaft gear 53b set at a high speed and is slid to a high speed engagement position where the fourth shift gear 55 is disengaged from the output shaft gear 54b set at a low speed. A high-speed shift state in which the power of the transmission relay shaft 42 is transmitted to the output shaft 43 by the high-speed setting gear pair 53 is established. That is, the output shaft gear 53b is interlocked with the output shaft 43 by the fourth shift gear 55 to be in a transmission-on state for transmitting power to the output shaft 43, and the output shaft gear 54b is released from the interlocking connection with the output shaft 43. The power transmission to the output shaft 43 is cut off.

  In the subtransmission 40B, when the fourth shift gear 55 is disengaged from the output shaft gear 53b set at a high speed, and is slid to a low speed entry position engaging with a side portion of the output shaft gear 54b set at a low speed, A low-speed shift state in which the power of the transmission relay shaft 42 is transmitted to the output shaft 43 by the low-speed setting gear pair 54 is established. That is, the output shaft gear 53b is released from the interlocking connection with the output shaft 43 to be in a transmission cutoff state in which power transmission to the output shaft 43 is cut off, and the output shaft gear 54b is interlockingly connected to the output shaft 43 by the fourth shift gear 55. As a result, a power transmission state for transmitting power to the output shaft 43 is established.

  In the subtransmission portion 40B, when the fourth shift gear 55 is slid to the neutral position where the fourth shift gear 55 is disengaged from the output shaft gear 53b set at a high speed and is disengaged from the output shaft gear 54b set at a low speed, transmission of the transmission is performed. A neutral state is established in which power transmission from the shaft 42 to the output shaft 43 is cut off. That is, the output shaft gear 53b is released from the interlocking connection with the output shaft 43 and is in a transmission cutoff state in which power transmission to the output shaft 43 is cut off, and the output shaft gear 54b is released from the interlocking connection with the output shaft 43 to output the output shaft 43. The power transmission to the power 43 is cut off. The sub-transmission portion 40 </ b> B enables the creep transmission device 60 to perform a shift operation by being shifted to a neutral state.

  As shown in FIGS. 2 and 4, the rear part of the output shaft 43 and the front part of the input shaft 70 a of the differential mechanism 70 are interlockingly connected by a connecting member 56. A gear interlocking mechanism 57 that transmits the power of the output shaft 43 to the front wheel transmission shaft 44 is provided over the rear portion of the output shaft 43 and the rear portion of the front wheel transmission shaft 44.

  In the gear transmission 40, the power input to the input shaft 41 by the rotary transmission shaft 28 is subjected to the main speed change by the gear pair operated in the shift operation state among the first speed gear pair 45 to the sixth speed gear pair 50. The transmission is transmitted to the transmission relay shaft 42, is subjected to a subtransmission by the subtransmission portion 40 </ b> B switched to the high speed transmission state or the low speed transmission state, is transmitted to the output shaft 43, and is transmitted from the output shaft 43 to the rear wheel differential mechanism 70 and the front wheels The power is transmitted to the transmission shaft 44. The power transmitted to the front wheel transmission shaft 44 is transmitted to the front portion of the front wheel transmission shaft 44 by a rotating shaft 58 interlocked with a front portion of the front wheel transmission shaft 44 via a front wheel speed increasing mechanism 58a and a front wheel transmission clutch 58b, as shown in FIG. (See FIG. 1), and transmitted to the left and right front wheels 1 by a front wheel differential mechanism (not shown) or the like, which is housed in the front wheel drive case 59.

[Configuration of creep transmission]
As shown in FIGS. 2 and 4, the creep transmission 60 includes an output shaft 43 and a creep shaft 61 serving as a relay shaft provided in parallel with the output shaft 43. As shown in FIG. 5, the creep shaft 61 is provided on the same lateral outside of the vehicle body as the side where the input shaft 41 is located with respect to the transmission relay shaft 42 and the output shaft 43. The creep shaft 61 is provided below the output shaft 43.

  As shown in FIG. 4, a first reduction gear 62 is supported by a creep shaft 61 so as to be relatively rotatable. The first reduction gear 62 is engaged with a first transmission gear 66 provided on the side of the output shaft gear 54b so as not to rotate relatively. The outer diameter of the first reduction gear 62 is formed larger than the outer diameter of the first transmission gear 66. The power of the output shaft gear 54b is transmitted to the first reduction gear 62 by the first transmission gear 66 that rotates together with the output shaft gear 54b, and the first reduction gear 62 rotates. The power of the output shaft gear 54b is reduced and transmitted to the first reduction gear 62.

  A second reduction gear 63 is supported on the output shaft 43 so as to be relatively rotatable. The second reduction gear 63 is engaged with a second transmission gear 67 provided on the side of the first reduction gear 62 so as not to rotate relatively. The outer diameter of the second reduction gear 63 is formed larger than the outer diameter of the second transmission gear 67. The power of the first reduction gear 62 is transmitted to the second reduction gear 63 by the second transmission gear 67 that rotates together with the first reduction gear 62, and the second reduction gear 63 rotates. The power of the first reduction gear 62 is reduced and transmitted to the second reduction gear 63.

  A third reduction gear 64 is supported by the creep shaft 61 so as to be relatively unrotatable. The third reduction gear 64 is engaged with a third transmission gear 68 provided on the side of the second reduction gear 63 so as not to rotate relatively. The outer diameter of the third reduction gear 64 is formed larger than the outer diameter of the third transmission gear 68. The power of the second reduction gear 63 is transmitted to the third reduction gear 64 by a third transmission gear 68 that rotates together with the second reduction gear 63, and the third reduction gear 64 rotates, and the creep shaft 61 is rotated by the third reduction gear 64. Rotated. The power of the second reduction gear 63 is reduced by the third reduction gear 64 and transmitted to the creep shaft 61.

  A reduction gear pair 65 is provided between the creep shaft 61 and the output shaft 43. In the direction along the axis of the creep shaft 61, the reduction gear pair 65 is disposed on the side opposite to the side where the first reduction gear 62 is located with respect to the output shaft gear 54b. The reduction gear pair 65 is composed of a transmission gear 65a supported rotatably on the creep shaft 61 and an output shaft reduction gear 65b supported on the output shaft 43 so as to be relatively non-rotatable while being engaged with the transmission gear 65a. It is configured. The outer diameter of the output shaft reduction gear 65b is formed larger than the outer diameter of the transmission gear 65a.

  A shift gear 69 as a clutch is provided between the transmission gear 65a and the creep shaft 61. The shift gear 69 is supported by the creep shaft 61 so as to be relatively non-rotatable and slidable.

  In the reduction gear pair 65, when the shift gear 69 is slid to the engaged position engaged with the side of the transmission gear 65a, the transmission gear 65a is connected to the creep shaft 61 by the shift gear 69 so that it cannot rotate relative to the transmission gear 65a. In this state, the power of the creep shaft 61 is reduced by the transmission gear 65a and the output shaft reduction gear 65b and transmitted to the output shaft 43.

  In the reduction gear pair 65, when the shift gear 69 is slid to the cutting position disengaged from the transmission gear 65a, the connection of the transmission gear 65a to the creep shaft 61 is released, and the transmission gear is cut off, and the output from the creep shaft 61 is output. Power transmission to the shaft 43 becomes impossible.

  In the present embodiment, a configuration is adopted in which the reduction gear pair 65 is switched between the transmission-on state and the transmission-off state by switching the transmission gear 65a between the connected state and the disconnected state with respect to the creep shaft 61. Not limited to this. The transmission gear 65a is rotatably supported on the creep shaft 61, and the output shaft reduction gear 65b is rotatably supported on the output shaft 43. The output shaft reduction gear 65b is connected to and disconnected from the output shaft 43. By employing a switchable clutch, a configuration may be employed in which the reduction gear pair 65 can be switched between a transmission-on state and a transmission-off state. The clutch is not limited to the shift gear 69, but may be a friction clutch, a dog clutch or the like.

  In the creep transmission device 60, when the reduction gear pair 65 is operated to enter the transmission state, the creep shaft 61 and the output shaft 43 are interlocked by the reduction gear pair 65 and the shift gear 69 to enter the transmission state. The power of the gear 54b is transmitted to the first reduction gear 62 by the first transmission gear 66, the power of the first reduction gear 62 is transmitted to the second reduction gear 63 by the second transmission gear 67, and the power of the second reduction gear 63. Is transmitted to the third reduction gear 64 by the third transmission gear 68, the creep shaft 61 is driven by the third reduction gear 64, and the power of the creep shaft 61 is transmitted to the output shaft 43 by the reduction gear pair 65. That is, the power of the output shaft gear 54b is reduced in the first stage by the first reduction gear 62, the second stage by the second reduction gear 63, the third stage by the third reduction gear 64, and the reduction gear pair. The speed is reduced and transmitted to the output shaft 43 by the deceleration in the fourth step by 65.

  In the creep speed change device 60, when the reduction gear pair 65 is operated to be in the transmission cutoff state, the interlocking connection between the creep shaft 61 and the output shaft 43 is released to be in the shift cutoff state, and the output shaft gear 53b and the output shaft gear The power transmitted from 54b to the output shaft 43 by the fourth shift gear 55 can be transmitted directly from the output shaft 43 to the input shaft 70a of the differential mechanism 70.

  In the traveling transmission device 14, when the forward / reverse switching device 20 is switched to the forward transmission state, the power of the engine 3 is converted into forward power by the forward / reverse switching device 20, and the converted forward power is converted into the high / low speed switching device 30. And the speed is shifted to a low speed side or a high speed side, and the shifted low speed side or high speed side forward power is input to the gear transmission 40 by the rotary transmission shaft 28 and the input shaft 41. When the forward / reverse switching device 20 is switched to the reverse transmission state, the power of the engine 3 is converted into reverse power by the forward / reverse switching device 20, and the converted reverse power is transmitted to the gear transmission 40 by the rotary transmission shaft 28 and the input shaft 41. Is entered. The power of the forward power or the reverse power input to the gear transmission 40 is transmitted to the output shaft 43 via the main transmission unit 40A and the auxiliary transmission unit 40B, and is input from the output shaft 43 to the differential mechanism 70 for the rear wheels. The power is transmitted to the left and right rear wheels 2. Further, the power is transmitted from the output shaft 43 to the front wheel transmission shaft 44, input from the front wheel transmission shaft 44 to the front wheel drive case 59, and transmitted to the left and right front wheels 1.

  Therefore, for example, when the loader work is performed, the front wheel 1 and the rear wheel 2 are driven by switching between the forward side and the reverse side only by switching the forward / reverse switching device 20 between the forward transmission state and the reverse transmission state. The vehicle can be switched between forward traveling and reverse traveling. When the high / low speed switching device 30 is switched to the high speed transmission state, the forward / reverse switching device 20 is switched to the reverse transmission state, and the rotational speed of the reverse power input to the gear transmission 40 by the rotary transmission shaft 28 and the input shaft 41; When the forward / reverse switching device 20 is switched to the forward transmission state, the rotational speed of the forward power input to the gear transmission 40 by the rotary transmission shaft 28 and the input shaft 41 becomes the same speed, and the forward traveling and the reverse traveling have the same traveling speed. Can be done with

  At the time of normal running or the like, the creep transmission 60 is switched to a shift-off state. Then, the power input to gear transmission 40 is subjected to main speed change by main transmission portion 40A and sub speed change by sub speed change portion 40B and transmitted to output shaft 43, so that creep speed change device 60 does not perform the speed change. To the front wheel 1 and the rear wheel 2.

  When a plow operation or the like is performed, the sub transmission unit 40B is switched to a neutral state, and the creep transmission 60 is switched to a shift-on state. Then, the power input to the gear transmission 40 and shifted by the main transmission unit 40A is input to the creep transmission 60 from the output shaft gear 54b of the sub transmission unit 40B set at a low speed by the first transmission gear 66, and the creep transmission 60 In the above, the creep speed is changed by four stages of deceleration by the first reduction gear 62, the reduction by the second reduction gear 63, the reduction by the third reduction gear 64, and the reduction by the reduction gear pair 65, which is transmitted to the output shaft 43 and output. The front wheel 1 and the rear wheel 2 can be driven at a low speed by being transmitted from the shaft 43 to the rear wheel differential mechanism 70 and the front wheel transmission shaft 44. In the present embodiment, the vehicle can run at a speed of about 0.2 km / h.

  In this embodiment, as shown in FIG. 5, the creep shaft 61 is provided on the same side as the side where the input shaft 41 is located with respect to the center line C, and the front wheel transmission shaft 44 is provided with respect to the center line C. Are provided on the side opposite to the side where is located. Since the distance between the creep shaft 61 and the center line C needs to be wider than the distance between the front wheel transmission shaft 44 and the center line C, the creep shaft 61 is opposite to the side where the input shaft 41 is located with respect to the center line C. Providing the front wheel transmission shaft 44 on the side opposite to the side where the input shaft 41 is located with respect to the center line C is more effective than providing the front wheel transmission shaft 44 on the side supported by the output shaft 43 and the side wall 11S of the transmission case 11 than on the side. The interval can be narrowed. The smaller the gap between the gear and the side wall portion 11S, the easier the lubricating oil in the transmission case is agitated by the rotating gear, and the more the lubricating oil is applied to the gears of the transmission relay shaft 42 and the input shaft 41 located above the output shaft 43. Easy to reach. Therefore, in the case of the present embodiment, the lubricating oil can easily reach the entire gear transmission 40 while keeping the oil level in the transmission case as low as possible.

[Another embodiment]
(1) FIG. 6 is a longitudinal sectional side view showing a traveling transmission device 114 having another embodiment. In the traveling transmission 114 having another embodiment, the high / low speed switching device 30 is omitted.

  In the forward / reverse switching device 20 provided in the traveling transmission 114, when the forward clutch 22F is switched to the on state, the power of the input shaft 21 is transmitted via the forward clutch 22F, the clutch output gear 80, and the input gear 81. And transmitted to the input shaft 41 of the gear transmission 40. When the reverse clutch 22R is switched to the engaged state, the power of the input shaft 21 is transmitted to the gear transmission 40 via the reverse clutch 22R, the clutch output gear 82, the reverse rotation gear 83, the rotation shaft 84, the transmission gear 85, and the input gear 81. It is transmitted to the input shaft 41.

(2) In the traveling transmission 14 shown in FIG. 2 and the traveling transmission 114 shown in FIG. 6, the forward / reverse switching device 20 is provided outside the gear transmission 40. The gear transmission 40 may have the function.

(3) In the above-described embodiment, the example in which the reduction gear pair 65 is provided on the side opposite to the side where the first reduction gear 62 is located with respect to the output shaft gear 54b has been described. The first reduction gear 62 may be provided on the same side as the side where the first reduction gear 62 is located with respect to the shaft gear 54b.

  The present invention can be applied to a tractor having a semi-crawler instead of the front wheel and the rear wheel.

Reference Signs List 3 engine 11 transmission case 20 forward / reverse switching device 22 clutch unit 23 forward output unit (forward output gear)
24 Reverse output unit (reverse output gear)
28 rotary transmission shaft 30 high / low speed switching device 40 gear transmission 41 input unit (input shaft)
54b Output shaft gear 60 Creep transmission 61 Relay shaft (creep shaft)
62 first reduction gear 63 second reduction gear 64 third reduction gear 65 reduction gear pair 66 first transmission gear 67 second transmission gear 68 third transmission gear 69 reduction gear pair 70 differential mechanism

Claims (8)

A gear transmission in which the power of the engine is input, and the input power is shifted and output;
An output of the gear transmission is input, a creep transmission that reduces the input power and outputs it to a rear wheel differential mechanism,
A transmission case that houses the gear transmission and the creep transmission,
An output shaft for transmitting power to the differential mechanism, a transmission-on state supported by the output shaft and engaged with the output shaft so as to be relatively non-rotatable and transmitting power to the output shaft; An output shaft gear that can be switched to a transmission cutoff state in which engagement with the output shaft is released and power transmission to the output shaft is interrupted,
In the creep transmission, a relay shaft parallel to the output shaft, a first transmission gear provided to be relatively non-rotatable with the output shaft gear, and a relative to the relay shaft in a state of being engaged with the first transmission gear. A first reduction gear rotatably supported and rotating at a lower speed than the first transmission gear; a second transmission gear provided to the first reduction gear so as to be relatively non-rotatable; and a second reduction gear. A second reduction gear that is rotatably supported by the output shaft in an engaged state and that rotates at a lower speed than the second transmission gear; and a third reduction gear that is provided on the second reduction gear so as to be relatively non-rotatable. A transmission gear, a third reduction gear that is rotatably supported by the relay shaft in a state of being engaged with the third transmission gear, and that rotates at a lower speed than the third transmission gear; An output shaft, and the relay shaft Traveling transmission system of a tractor in which the reduction gear pair can be switched between a power transmission cut state break off power transmission for transmitting cored with said output shaft for transmitting the output shaft decelerates power, is provided.   The traveling of the tractor according to claim 1, wherein the reduction gear pair is located on a side opposite to a side where the first reduction gear is located with respect to the output shaft gear in a direction along an axis of the relay shaft. Gearing. The relay shaft is provided below the output shaft,
A clutch for switching the reduction gear pair between the transmission-on state and the transmission-off state is provided over the transmission gear of the reduction gear pair supported by the relay shaft and the relay shaft. 3. The traveling transmission for a tractor according to 1 or 2. The power of the engine is input, a clutch unit that converts the input power into forward power and reverse power is provided, and a forward output unit that outputs the converted forward power and outputs the converted reverse power A forward / backward switching device having a reverse output unit separately,
A rotation transmission shaft that is provided across the reverse output portion and the input portion of the gear transmission, and transmits power of the reverse output portion to the input portion;
A high-speed transmission state in which the power of the forward output unit is shifted to a high speed side and transmitted to the rotary transmission shaft, and the power of the forward output unit is shifted to a low speed side. The traveling transmission device for a tractor according to any one of claims 1 to 3, further comprising a high / low speed switching device capable of switching to a low speed transmission state for transmitting to the rotary transmission shaft.   The traveling transmission device for a tractor according to claim 4, wherein the rotary transmission shaft and the input unit are provided concentrically and in a straight line.   The traveling transmission device for a tractor according to claim 4 or 5, wherein the reverse output portion is provided on a front side of the clutch portion, and the forward output portion is provided on a rear side of the clutch portion. Engine power is input, the input power is converted into forward power and reverse power, and a forward output section that outputs the converted forward power and a reverse output section that outputs the converted reverse power are separately provided. Forward and backward switching device,
A gear transmission that has an input unit to which power is input, and that shifts the power input to the input unit and outputs the power to the traveling device;
A rotation transmission shaft that is provided across the reverse output portion and the input portion and that transmits power of the reverse output portion to the input portion;
The power output from the forward output unit is provided between the forward output unit and the rotation transmission shaft, and the power output from the forward output unit is shifted between a high speed side and a low speed side. And a high / low speed switching device for outputting to a shaft.   A tractor comprising the tractor traveling transmission device according to any one of claims 1 to 7.

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