JP2017036773A - Auxiliary shifting device and work vehicle equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary shifting device capable of simplifying a shifter, improving flexibility in speed reduction ratio setting, and reducing a cost.SOLUTION: An auxiliary shifting gear unit 20 is equipped with an auxiliary transmission shaft 50; an auxiliary gear shift shaft 60; a first transmission gear 51, an auxiliary gear shifting first speed gear 61; an auxiliary transmission shaft shift gear 54; an auxiliary gear shifting shaft third speed gear 63; an auxiliary transmission shaft shifter 55; an auxiliary speed change shifter 67; and a fork shaft 80. The auxiliary shifting gear unit 20 is configured so as to be switched between an auxiliary gear shifting first speed and an auxiliary gear shifting third speed of a high-speed stage, by making the fork shaft 80 moved by cooperating the auxiliary transmission shaft shifter 55 and the auxiliary speed change shifter 67, to slide in an axial direction. At the auxiliary gear shifting first speed, the auxiliary speed change shifter 67 is coupled with the auxiliary gear shifting first speed gear 61 so as not to relatively rotate, and the auxiliary transmission shaft shifter 55 is not coupled with the auxiliary transmission shaft shift gear 54. At the auxiliary gear shifting third speed, the auxiliary speed change shifter 67 is not coupled with the auxiliary gear shifting first speed gear 61, and the auxiliary transmission shaft shifter 55 is coupled with the auxiliary transmission shaft shift gear 54 so as not to relatively rotate.SELECTED DRAWING: Figure 6

Description

  The present invention mainly relates to an auxiliary transmission device for a work vehicle.

  2. Description of the Related Art Conventionally, there is known a sub-transmission having a sub-transmission shaft that transmits rotational power from an engine transmitted by a main transmission with a sub-transmission shifter that can be switched to three speeds and transmits it to a rear wheel. Patent Document 1 discloses a power transmission mechanism including this type of auxiliary transmission.

  The power transmission mechanism of Patent Document 1 is provided with a sub-shift shifter on a sub-transmission shaft, and a sub-shift third speed, a sub-speed second speed, It is configured to be able to switch to the first speed change, neutral, and sub-speed ultra-low speed.

JP2013-241125A

  In the configuration of the above-mentioned Patent Document 1, in order to realize a three-stage shift, teeth that can mesh with a gear disposed with the sub-shift shifter interposed at one end and the other end in the axial direction of the sub-shift shifter. Is provided. Each of the gears arranged on both sides of the auxiliary transmission shifter is formed with teeth for meshing with (combining with) the auxiliary transmission shifter. Further, external teeth are formed on the outer peripheral surface of the auxiliary transmission shifter, and the external teeth are configured to be able to mesh with a gear disposed on the transmission shaft. The auxiliary transmission shifter is slidably provided on the auxiliary transmission shaft so as to selectively engage with one of the three gears. Therefore, in the configuration of Patent Document 1, the auxiliary transmission shifter is complicated, and it is necessary to ensure a large slide stroke of the auxiliary transmission shifter, which makes it difficult to reduce the size.

  Further, in Patent Document 1, when it is desired to increase the speed of a vehicle, it is necessary to make the gear on the high speed stage side small, in particular, of the two driven gears arranged with the auxiliary transmission shifter interposed therebetween. However, if the gear is made smaller, it becomes difficult to form teeth on the gear for meshing with the auxiliary transmission shifter, so that the degree of freedom in setting the reduction ratio is practically limited.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sub-transmission that can realize simplification of a shifter, improvement in freedom of setting a reduction ratio, and cost reduction.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to a first aspect of the present invention, a sub-transmission apparatus having the following configuration is provided. That is, the auxiliary transmission includes a transmission shaft, an auxiliary transmission shaft, a first output gear, a first input gear, a second output gear, a second input gear, a transmission shaft shifter, an auxiliary transmission shifter, A fork shaft. Power from the main transmission is transmitted to the transmission shaft. The power of the transmission shaft is shifted and transmitted to the auxiliary transmission shaft. The first output gear rotates integrally with the transmission shaft. The first input gear meshes with the first output gear and is supported by the auxiliary transmission shaft so as to be relatively rotatable. The second output gear is supported by the transmission shaft so as to be relatively rotatable. The second input gear meshes with the second output gear and rotates integrally with the auxiliary transmission shaft. The transmission shaft shifter is disposed on the transmission shaft. The auxiliary transmission shifter is disposed on the auxiliary transmission shaft. The fork shaft moves the transmission shaft shifter and the auxiliary transmission shifter in conjunction with each other. The transmission shaft shifter is formed with an internal spline that is not rotatable relative to the transmission shaft and is slidable in the axial direction. The auxiliary transmission shifter is formed with an internal spline that is not rotatable relative to the auxiliary transmission shaft and is slidable in the axial direction. The first input gear is formed with a fitting portion that can mesh with the internal spline of the auxiliary transmission shifter. The second output gear is formed with a fitting portion that can mesh with the internal spline of the transmission shaft shifter. The auxiliary transmission is configured to be switchable between a first state and a second state by sliding the fork shaft in the axial direction. In the first state, the auxiliary transmission shifter couples the fitting portion of the first input gear and the auxiliary transmission shaft so as not to rotate relative to each other, and the transmission shaft shifter includes the second output gear and the transmission shaft. Do not combine. In the second state, the auxiliary transmission shifter does not couple the first input gear and the auxiliary transmission shaft, and the transmission shaft shifter relatively rotates the fitting portion of the second output gear and the transmission shaft. Join impossible. The second state is a higher speed stage than the first state.

  As a result, the coupling between the first input gear and the auxiliary transmission shifter and the coupling between the second output gear and the transmission shaft shifter are realized by fitting the fitting portions formed on the respective gears to the internal splines of the shifter. Therefore, it is possible to simplify the configuration of each shifter while realizing a linear shift. Further, even when it is desired to increase the speed in the second state, since the fitting portion is formed in the second output gear on the driving side (which should have a large diameter), it is not necessary to make the fitting portion particularly compact. Therefore, the reduction ratio setting and the degree of freedom in layout can be increased. In addition, by providing shifters individually on different axes, the sliding distance of each shifter can be shortened compared to a configuration in which only one shifter is provided. Therefore, it is possible to reduce the size of the auxiliary transmission in the axial direction.

  The auxiliary transmission can be configured as follows. In other words, the auxiliary transmission includes a third output gear and a third input gear. The third output gear rotates integrally with the transmission shaft. The third input gear meshes with the third output gear and is supported by the auxiliary transmission shaft so as to be relatively rotatable. The third input gear is formed with a fitting portion that can mesh with the internal spline of the auxiliary transmission shifter. In the auxiliary transmission, the auxiliary transmission shifter couples the fitting portion of the third input gear and the auxiliary transmission shaft so as not to be relatively rotatable by sliding the fork shaft in the axial direction, and the transmission shaft The shifter is configured to be switchable to a third state in which the second output gear and the transmission shaft are not coupled.

  As a result, speed stage switching of three or more stages can be realized by linear shift. In addition, by providing a shifter and gear component on one shaft, the configuration of each shifter is simplified compared to a configuration that realizes three speed stage switching, so that it is easy to manufacture the parts and reduce the cost. Reduction can be achieved.

  The auxiliary transmission can be configured as follows. In other words, the auxiliary transmission includes a third output gear and a third input gear. The third output gear is supported by the transmission shaft so as to be relatively rotatable. The third input gear meshes with the third output gear and rotates integrally with the auxiliary transmission shaft. The third output gear is formed with a fitting portion that can mesh with the internal spline of the transmission shaft shifter. The auxiliary transmission shifts the fork shaft in the axial direction so that the transmission shaft shifter couples the fitting portion of the third output gear and the transmission shaft so as not to be relatively rotatable, and the auxiliary transmission shifter Is configured to be switchable to a third state in which the first input gear and the auxiliary transmission shaft are not coupled.

  As a result, speed stage switching of three or more stages can be realized by linear shift. In addition, by providing a shifter and gear component on one shaft, the configuration of each shifter is simplified compared to a configuration that realizes three speed stage switching, so that it is easy to manufacture the parts and reduce the cost. Reduction can be achieved.

  In the auxiliary transmission, the fork shaft is slid in the axial direction, and is switched between the first state, the second state, and the third state so as to be in a high speed stage sequentially from one side. It is preferable.

  As a result, a natural auxiliary transmission operation can be performed.

  According to a second aspect of the present invention, a work vehicle including the auxiliary transmission is provided.

  As a result, the coupling between the first input gear and the auxiliary transmission shifter and the coupling between the second output gear and the transmission shaft shifter are realized by fitting the fitting portions formed on the respective gears to the internal splines of the shifter. Therefore, it is possible to simplify the configuration of each shifter while realizing a linear shift. As a result, parts can be easily manufactured, and costs can be reduced. Further, even when it is desired to increase the speed in the second state, since the fitting portion is formed in the second output gear on the driving side (which should have a large diameter), it is not necessary to make the fitting portion particularly compact. Therefore, the reduction ratio setting and the degree of freedom in layout can be increased. In addition, by providing shifters individually on different axes, the sliding distance of each shifter can be shortened compared to a configuration in which only one shifter is provided. Therefore, it is possible to reduce the size of the auxiliary transmission in the axial direction. In addition, since it is possible to realize the interlocking of the two shifters arranged on different axes with a simple configuration, the configuration of the work vehicle can be made compact.

The right view of a tractor provided with the auxiliary transmission which concerns on 1st Embodiment of this invention. The right view which shows the structure in the mission case with which a tractor is equipped. The top view which shows the structure in the mission case with which a tractor is equipped. The skeleton figure of the power transmission system in a tractor. The cross-sectional expanded view which shows a part of mission case. FIG. 3 is a cross-sectional development view showing a power cut-off state in which the sub-transmission shaft shifter and the sub-transmission shifter are at a reference position and no power is transmitted in the auxiliary transmission. FIG. 3 is a cross-sectional development view of the auxiliary transmission device showing a state of the auxiliary transmission first speed. FIG. 3 is a cross-sectional development view of the auxiliary transmission device showing a state of the auxiliary transmission second speed. FIG. 7 is a developed cross-sectional view of the sub-transmission device showing a power cutoff state in which the positions of the sub-transmission shaft shifter and the sub-transmission shifter are different from those in FIG. FIG. 3 is a cross-sectional development view of the auxiliary transmission device showing a state of the auxiliary transmission third speed. FIG. 9 is a cross-sectional development view showing a power cut-off state in which a sub-transmission shaft shifter and a sub-transmission shifter are in a reference position and power is not transmitted in the sub-transmission device of the second embodiment.

  Next, embodiments of the present invention will be described with reference to the drawings. First, with reference to FIG. 1, the whole structure of the tractor 100 provided with the auxiliary transmission 20 which concerns on this invention is demonstrated easily. FIG. 1 is a right side view of a tractor 100 including an auxiliary transmission 20 according to the first embodiment of the present invention. In the following description, “left”, “right”, and the like mean left and right in the direction in which the tractor 100 moves forward.

  A tractor 100 as a work vehicle for agricultural work shown in FIG. 1 is configured so that various work devices (work machines) such as plows and loaders can be mounted as necessary to perform various types of work. Yes.

  As shown in FIG. 1, the tractor 100 includes an airframe 2, a pair of left and right front wheels 101, and a pair of left and right rear wheels 102. The front wheel 101 supports the front part of the body 2, and the rear wheel 102 supports the rear part of the body 2. An engine 105 as a drive source is disposed inside the hood 106 at the front of the machine body 2.

  As shown in FIG. 1, a cabin 112 for an operator to board is installed on the upper surface of the airframe 2 behind the hood 106. Inside the cabin 112, a seat 111 for an operator to sit is disposed. Around the seat 111, various operating tools including a steering handle 110, a main transmission lever, a sub transmission lever, a clutch pedal, a PTO transmission lever, and a reverser lever are provided. The seat 111 and the above-described operation tool and the like are disposed in a driving unit configured in the cabin 112.

  On the left and right outer sides of the cabin 112, steps 113 and 113 on which the operator gets on and off are provided. A fuel tank that supplies fuel to the engine 105 is disposed in front of the cabin 112, and this fuel tank is accommodated in the hood 106.

  The frame constituting the structure of the airframe 2 is composed of an unillustrated engine frame having a front bumper 114 and a front axle case 115, and left and right airframe frames 116 and 116 detachably fixed to the rear portion of the engine frame. ing. A mission case 109 is connected to the rear part of the body frame 116. The transmission case 109 houses therein a mechanism for appropriately shifting the rotational power from the engine 105 and transmitting it to the front and rear wheels.

  A rear wheel 102 is attached to the mission case 109 via a rear axle 117. The transmission case 109 decelerates the power from the engine 105 and transmits it to the front axle case 115 and the rear axle 117. When the operator operates the speed change tool, the speed ratio of the mission case 109 can be changed and the traveling speed of the tractor 100 can be adjusted. Details will be described later. Upper portions of the left and right rear wheels 102 are covered with left and right rear fenders 118.

  The engine 105 is configured as a diesel engine and functions as a drive source for the tractor 100. The configuration of the engine 105 is not limited to the above, and may be configured as, for example, a gasoline engine.

  A clutch housing (not shown) is disposed behind the engine 105, and the above-described transmission case 109 is disposed behind the clutch housing. As a result, the driving force from the engine 105 can be transmitted to the rear wheel 102 while being shifted and driven. Further, it is possible to transmit the output of the mission case 109 not only to the rear wheel 102 but also to the front wheel 101 at the same time.

  The driving force of the engine 105 is transmitted to the PTO shaft 119 protruding from the rear end of the mission case 109. The tractor 100 is configured such that the above-described working machine can be attached to the rear end thereof. The PTO shaft 119 can drive the work machine via a universal joint or the like (not shown).

  As shown in FIGS. 2 to 5, a hydraulic continuously variable transmission (HST) 120 for appropriately shifting the rotational power transmitted from the engine 105 is accommodated in the mission case 109. The rotational power of the engine 105 is transmitted to the main transmission input shaft 121 of the transmission case 109 via the main clutch 91 shown in FIG. 4 and is appropriately shifted by the hydraulic continuously variable transmission 120 and the traveling transmission gear mechanism, It is transmitted to the rear wheel 102.

  The hydraulic continuously variable transmission 120 functions as a main transmission, and includes a hydraulic pump 124 and a hydraulic motor 126 that are connected to each other by a hydraulic circuit. The hydraulic pump 124 is driven by the main transmission input shaft 121, while the hydraulic motor 126 drives the auxiliary transmission shaft (transmission shaft) 50.

  One of the hydraulic pump 124 and the hydraulic motor 126 is a fixed capacity type, and the other is a variable capacity type. In the present embodiment, the hydraulic motor 126 is a fixed displacement type, the hydraulic pump 124 is a variable displacement type, and the hydraulic pump 124 is provided with an output adjusting member. The hydraulic motor 126 may be a variable displacement type and the hydraulic pump 124 may be a fixed displacement type.

  The output adjusting member includes a movable swash plate 125 and a control shaft (not shown) that changes the inclination angle of the movable swash plate 125. Then, the control shaft is rotated around the axis by a shift actuator such as a hydraulic cylinder that operates in accordance with the operation of an operation tool such as a main shift lever or a shift switch provided in the vicinity of the seat 111. The discharge amount of the hydraulic pump 124 can be changed by changing the inclination angle of the plate 125.

  The main transmission input shaft 121 is disposed such that its axis extends in the front-rear direction. An output shaft 90 of the engine 105 is connected to the front end of the main transmission input shaft 121 via a main clutch 91. The main transmission input shaft 121 extends rearward so as to pass through the hydraulic pump 124, and an output transmission shaft 92 is connected to the rear end thereof. The output transmission shaft 92 is configured to rotate integrally with the main transmission input shaft 121. The sub-transmission shaft 50 as the main transmission output shaft is also arranged such that its axis extends in the front-rear direction.

  The output transmission shaft 92, the auxiliary transmission shaft 50, and the front wheel transmission shaft 10 are arranged in parallel to each other behind the hydraulic continuously variable transmission 120 in the transmission case 109. The sub-transmission shaft 50 is disposed so as to protrude rearward from the hydraulic motor 126, and the rotation continuously shifted by the hydraulic continuously variable transmission 120 is output to the sub-transmission shaft 50.

  A front wheel drive output shaft 70 is connected to the rear end portion of the front wheel transmission shaft 10. Further, a PTO transmission mechanism 130 for appropriately changing the rotation of the PTO shaft 119 is provided behind the output transmission shaft 92. The power of the engine 105 transmitted to the output transmission shaft 92 is appropriately shifted by the PTO transmission mechanism 130 and then transmitted to the PTO clutch shaft 93 and output to the PTO shaft 119. With this configuration, it is possible to transmit power to the working machine attached to the rear end of the tractor 100 and drive it.

  Next, a configuration for transmitting power in the tractor 100 will be described with reference to FIGS. 4 and 5. FIG. 4 is a skeleton diagram of a power transmission system in the tractor 100. FIG. 5 is a developed sectional view showing a part of the mission case 109.

  A multi-plate main clutch 91 is disposed in the clutch housing, and the main clutch 91 can be switched between power transmission / cut-off by the clutch pedal. Then, after the rotation of the output shaft 90 of the engine 105 is input to the main clutch 91, the output of the main clutch 91 is input to the hydraulic pump 124 via the main transmission input shaft 121 and also via the output transmission shaft 92. Input to the PTO transmission mechanism 130.

  As shown in FIG. 4, the tractor 100 includes an output transmission shaft 92, a PTO clutch shaft 93, an auxiliary transmission device 20, a front wheel drive for transmitting the power of the engine 105 from the output shaft 90 to the rear wheels 102 and the like. And an output shaft 70. Each of the shafts is provided in the mission case 109 so that the axial direction thereof is the front-rear direction of the tractor 100.

  As shown in FIG. 4, the output shaft 90, the output transmission shaft 92, and the PTO clutch shaft 93 of the engine 105 are provided side by side in the front-rear direction of the tractor 100 so that their axes coincide with each other.

  The PTO clutch shaft 93 is disposed so as to extend rearward of the body 2 of the tractor 100. The rotation of the output shaft 90 of the engine 105 is input to the main clutch 91 for switching between transmission / cutoff of power and then transmitted to the PTO clutch shaft 93 via the output transmission shaft 92. The power of the PTO clutch shaft 93 is transmitted to the PTO shaft 119 via the reduction gear 129 and can drive the working machine mounted on the rear end of the machine body 2.

  A main transmission shaft gear 94 is attached to the output transmission shaft 92 so as not to be relatively rotatable. A fourth main transmission gear 34 is attached to the main transmission shaft 30 disposed in parallel with the main clutch 91 so as not to be relatively rotatable. The main transmission shaft gear 94 meshes with the fourth main transmission gear 34. Thereby, the rotation of the output transmission shaft 92 is transmitted to the main transmission shaft 30.

  A PTO first speed gear 95, a PTO second speed gear 96, and a PTO reverse gear 97 are arranged on the PTO clutch shaft 93. The PTO first speed gear 95, the PTO second speed gear 96, and the PTO reverse gear 97 are supported so as to be rotatable relative to the PTO clutch shaft 93.

  In addition to the fourth main transmission gear 34, a first main transmission gear 31, a second main transmission gear 32, and a third main transmission gear 33 are arranged on the main transmission shaft 30. The first main transmission gear 31, the second main transmission gear 32, and the third main transmission gear 33 are attached to the main transmission shaft 30 so as not to be relatively rotatable.

  The first main transmission gear 31 meshes with a counter gear 15 that is rotatably supported, and this counter gear 15 meshes with a PTO reverse rotation gear 97. The second main transmission gear 32 meshes with the PTO first speed gear 95, and the third main transmission gear 33 meshes with the PTO second speed gear 96.

  Two PTO clutch sliders 98 and 99 are disposed on the PTO clutch shaft 93 so as not to rotate relative to the PTO clutch shaft 93 and to be slidable in the axial direction. The PTO clutch sliders 98 and 99 can be moved in the axial direction by operating an unillustrated PTO shift lever disposed in the cabin 112. When the operator operates the PTO shift lever, the PTO clutch slider 98 is coupled to the main transmission shaft gear 94, the PTO clutch slider 98 is coupled to the PTO reverse rotation gear 97, and the PTO clutch slider 99 is coupled to the PTO 1st gear. 95, and a state in which the PTO clutch slider 99 is connected to the PTO second gear 96, and the rotation (or the rotation in the reverse direction) shifted in three stages is obtained on the PTO clutch shaft 93. it can.

  The sub transmission shaft 50 is arranged in parallel with the output transmission shaft 92 and is rotatably supported. A first transmission gear 51 (first output gear) and a second transmission gear (third output gear) 52 are arranged on the auxiliary transmission shaft 50. The first transmission gear 51 and the second transmission gear 52 rotate integrally with the sub transmission shaft 50.

  The sub-transmission device 20 is configured to shift the rotation of the sub-transmission shaft 50 and transmit it to the sub-transmission shaft 60 disposed in parallel with the sub-transmission shaft 50.

  In addition to the first transmission gear 51 and the second transmission gear 52, a sub transmission shaft speed change gear (second output gear) 54 is disposed on the sub transmission shaft 50. The sub transmission shaft transmission gear 54 is supported so as to be rotatable relative to the sub transmission shaft 50.

  The auxiliary transmission shaft 60 includes an auxiliary transmission first speed gear (first input gear) 61, an auxiliary transmission second speed gear (third input gear) 62, an auxiliary transmission shaft third gear (second input gear) 63, An auxiliary transmission shaft fourth gear 64, an auxiliary transmission shaft fifth gear 65, and an auxiliary transmission shaft sixth gear 66 are arranged. The auxiliary transmission first speed gear 61 and the auxiliary transmission second speed gear 62 are supported by the auxiliary transmission shaft 60 so as to be relatively rotatable. On the other hand, the auxiliary transmission shaft third gear 63, the auxiliary transmission shaft fourth gear 64, the auxiliary transmission shaft fifth gear 65, and the auxiliary transmission shaft sixth gear 66 are configured to rotate integrally with the auxiliary transmission shaft 60. Yes.

  The first transmission gear 51 disposed on the sub-transmission shaft 50 meshes with the sub-transmission first speed gear 61, and the second transmission gear 52 meshes with the sub-transmission second speed gear 62. The auxiliary transmission shaft transmission gear 54 meshes with the auxiliary transmission shaft third gear 63.

  On the auxiliary transmission shaft 60, an auxiliary transmission shifter 67 is disposed between the auxiliary transmission first speed gear 61 and the auxiliary transmission second speed gear 62. The auxiliary transmission shifter 67 is spline-fitted so as not to rotate relative to the auxiliary transmission shaft 60 and to be slidable in the axial direction. The auxiliary transmission shifter 67 can be coupled to the auxiliary transmission first speed gear 61 or the auxiliary transmission second speed gear 62 so as not to rotate relative to each other by moving in the axial direction.

  In the sub-transmission shaft 50, a sub-transmission shaft shifter (transmission shaft shifter) 55 is disposed behind the sub-transmission shaft transmission gear 54. The sub-transmission shaft shifter 55 is spline-fitted to the sub-transmission shaft 50 so that it cannot rotate relative to the sub-transmission shaft 50 and can slide in the axial direction. The auxiliary transmission shaft shifter 55 can be coupled to the auxiliary transmission shaft transmission gear 54 so as not to rotate relative to the auxiliary transmission shaft transmission gear 54 by moving in the axial direction.

  The auxiliary transmission shifter 67 and the auxiliary transmission shaft shifter 55 are connected to an unillustrated auxiliary transmission lever provided in the cabin 112 via a fork shaft 80 described later. Accordingly, when the operator operates the auxiliary transmission lever, the auxiliary transmission shifter 67 and the auxiliary transmission shaft shifter 55 are moved in the axial direction, and the auxiliary transmission shifter 67 is coupled to the auxiliary transmission first gear 61, Switching between the state in which the shifter 67 is coupled to the sub-transmission second gear 62 and the state in which the sub-transmission shaft shifter 55 is coupled to the sub-transmission shaft transmission gear 54 is performed, and the rotation shifted in three stages is applied to the sub-transmission shaft 60 Can be obtained.

  A sub-transmission shaft fourth gear 64, a sub-transmission shaft fifth gear 65, and a sub-transmission shaft sixth gear 66 are disposed on the sub transmission shaft 60. The auxiliary transmission shaft fourth gear 64, the auxiliary transmission shaft fifth gear 65, and the auxiliary transmission shaft sixth gear 66 rotate integrally with the auxiliary transmission shaft 60. The power transmitted to the auxiliary transmission shaft 60 is output to the rear wheel drive system and the front wheel drive system by the auxiliary transmission shaft fourth gear 64, the auxiliary transmission shaft fifth gear 65, and the auxiliary transmission shaft sixth gear 66, respectively.

  The rear wheel drive system will be described. A rear wheel differential device 75 is disposed at the rear of the mission case 109. The rotation of the auxiliary transmission shaft 60 is input to the rear wheel differential device 75 through a conical auxiliary transmission shaft sixth gear 66 formed at the rear end of the auxiliary transmission shaft 60, and is transmitted to the rear through the rear axle 117 and the like. The wheel 102 is driven.

  The front wheel drive system will be described. A speed increasing drive input gear 71 and a standard drive input gear 72 are arranged on the front wheel drive output shaft 70. The speed increasing drive input gear 71 and the standard drive input gear 72 are supported to be rotatable relative to the front wheel drive output shaft 70, respectively. The sub-transmission shaft fourth gear 64 of the sub-transmission shaft 60 meshes with the speed increasing drive input gear 71, and the sub-transmission shaft fifth gear 65 meshes with the standard drive input gear 72. A switching mechanism 73 is disposed between the speed increasing drive input gear 71 and the standard drive input gear 72 in the front wheel drive output shaft 70. The switching mechanism 73 is configured to transmit the rotation of the speed increasing drive input gear 71 or the standard drive input gear 72 to the front wheel drive output shaft 70. The rotation of the front wheel drive output shaft 70 is input to the front wheel side differential device 74 via the shaft and gears, and drives the front wheel 101 via the axle or the like in the front axle case 115.

  Next, features of the auxiliary transmission 20 of the present embodiment will be described in detail. FIG. 5 is a developed sectional view showing a part of the mission case 109. FIG. 6 is a developed cross-sectional view showing a power cut-off state in which the sub-transmission shaft shifter 55 and the sub-transmission shifter 67 are at the reference position and no power is transmitted in the sub-transmission device 20. Further, FIGS. 6 to 10 show respective states of the auxiliary transmission 20 that are switched by the movement of the auxiliary transmission shaft shifter 55 and the auxiliary transmission shifter 67.

  In the auxiliary transmission 20 of the present embodiment, the transmission / interruption of the power of the clutches of the two shafts is switched in conjunction with the movement of the two shift shifters provided on different shafts, The speed stage is switched. In other words, the sub-transmission shaft shifter 55 disposed on the sub-transmission shaft 50 and the sub-transmission shifter 67 disposed on the sub-transmission shaft 60 move in conjunction with each other, so that the speed stage is switched.

  As described above, the auxiliary transmission shifter 67 is attached to the auxiliary transmission shaft 60 at a position between the auxiliary transmission first speed gear 61 and the auxiliary transmission second speed gear 62. As shown in FIG. 6, the auxiliary transmission shifter 67 includes a short cylindrical clutch hub 67a fixed to rotate integrally with the auxiliary transmission shaft 60, and a ring-shaped slider disposed outside the clutch hub 67a. 67b. Splines are formed on the outer peripheral surface of the clutch hub 67a.

  The slider 67b has substantially the same dimensions as the clutch hub 67a in the axial direction. An internal spline corresponding to the spline on the outer peripheral surface of the clutch hub 67a is formed on the inner peripheral surface of the slider 67b. As the spline of the clutch hub 67a and the internal spline of the slider 67b mesh with each other, the slider 67b and the clutch hub 67a rotate integrally. The slider 67b is configured to be slidable in the axial direction of the auxiliary transmission shaft 60 with respect to the clutch hub 67a by the spline coupling described above.

  The auxiliary transmission first speed gear 61 is arranged on one side in the axial direction of the clutch hub 67a, and the auxiliary transmission second speed gear 62 is arranged on the other side. The auxiliary transmission first speed gear 61 and the auxiliary transmission second speed gear 62 are supported so as to be rotatable relative to the auxiliary transmission shaft 60. The first transmission gear 51 fixed to the auxiliary transmission shaft 50 is engaged with the auxiliary transmission first speed gear 61, and the second transmission gear 52 is engaged with the auxiliary transmission second speed gear 62. The gear ratio of the gear train composed of the first transmission gear 51 and the auxiliary transmission first speed gear 61 is different from the gear ratio of the gear train composed of the second transmission gear 52 and the auxiliary transmission second speed gear 62.

  The auxiliary transmission first speed gear 61 and the auxiliary transmission second speed gear 62 are each formed with a boss portion protruding so as to approach the clutch hub 67a. A fitting portion 61a made of spline teeth is formed on the outer peripheral surface of the end portion on the side close to the clutch hub 67a in the boss portion of the auxiliary first speed gear 61. Similarly, a fitting portion 62a made of spline teeth is formed on the outer peripheral surface of the end portion close to the clutch hub 67a in the boss portion of the auxiliary transmission second speed gear 62. Both the spline of the fitting portion 61a of the auxiliary transmission first speed gear 61 and the spline of the fitting portion 62a of the auxiliary transmission second speed gear 62 can mesh with the internal spline formed on the slider 67b.

  In this configuration, as shown in FIG. 6, when the slider 67b is in a position where it does not protrude substantially from the clutch hub 67a in the axial direction, the slider 67b is also connected to the fitting portion 61a of the auxiliary transmission first speed gear 61. The rotation of the sub transmission shaft 50 is not transmitted to the sub transmission shaft 60 because it is not coupled to the fitting portion 62 a of 62. On the other hand, as shown in FIG. 7, when the slider 67b is in a position straddling the clutch hub 67a and the fitting portion 61a of the auxiliary first speed gear 61, the auxiliary first speed gear 61 and the clutch hub 67a are interposed via the slider 67b. Therefore, the rotation of the auxiliary transmission first speed gear 61 is transmitted to the auxiliary transmission shaft 60. In addition, as shown in FIG. 8, when the slider 67b is located at a position straddling the clutch hub 67a and the fitting portion 62a of the auxiliary transmission second speed gear 62, the auxiliary transmission second speed gear 62 and the clutch hub 67a are interposed via the slider 67b. Therefore, the rotation of the auxiliary transmission second speed gear 62 is transmitted to the auxiliary transmission shaft 60.

  As shown in FIG. 6 and the like, the axial dimension of the boss portion of the sub-transmission second speed gear 62 is slightly longer than that of the clutch hub 67a. As a result, the slider 67b can be moved to a position (position shown in FIG. 9 or FIG. 10) that only meshes with the fitting portion 62a of the sub-transmission second speed gear 62. In this case, since the slider 67b is disengaged from the clutch hub 67a, the rotation of the auxiliary transmission second speed gear 62 is not transmitted to the auxiliary transmission shaft 60.

  As described above, the auxiliary transmission shaft shifter 55 is attached to the auxiliary transmission shaft 50 at a position on one side in the axial direction of the auxiliary transmission shaft transmission gear 54. As shown in FIG. 6, the sub-transmission shaft shifter 55 includes a cylindrical clutch hub 55a fixed so as to rotate integrally with the sub-transmission shaft 50, and a ring-shaped slider disposed outside the clutch hub 55a. 55b. Splines are formed on the outer peripheral surface of the clutch hub 55a.

  The slider 55b has a shorter dimension than the clutch hub 55a in the axial direction. An internal spline corresponding to the spline on the outer peripheral surface of the clutch hub 55a is formed on the inner peripheral surface of the slider 55b. When the spline of the clutch hub 55a and the internal spline of the slider 55b mesh with each other, the slider 55b and the clutch hub 55a rotate integrally. The slider 55b is configured to slide in the axial direction of the sub-transmission shaft 50 with respect to the clutch hub 55a by the spline coupling.

  On one side in the axial direction of the clutch hub 55a (specifically, on the same side of the auxiliary transmission shaft 60 where the auxiliary transmission second speed gear 62 is disposed with respect to the clutch hub 67a), the auxiliary transmission shaft transmission gear 54 is provided. Has been placed. The sub transmission shaft transmission gear 54 is supported so as to be rotatable relative to the sub transmission shaft 50. The auxiliary transmission shaft transmission gear 54 is fixed to the auxiliary transmission shaft 60 and meshes with an auxiliary transmission shaft third gear 63 that rotates integrally with the auxiliary transmission shaft 60. The gear ratio of the gear train composed of the sub-transmission shaft transmission gear 54 and the sub-transmission shaft third gear 63 is the same as the gear ratio of the gear train composed of the first transmission gear 51 and the sub-transmission first speed gear 61 and the second transmission gear 52. It is also different from the gear ratio of the gear train composed of the sub-speed 2nd gear 62.

  The auxiliary transmission shaft transmission gear 54 is formed with a boss projecting so as to approach the clutch hub 55a. In the boss portion of the auxiliary transmission shaft transmission gear 54, a fitting portion 54a made of spline teeth is formed on the outer peripheral surface of the end portion on the side close to the clutch hub 55a. The spline of the fitting portion 54a of the auxiliary transmission shaft transmission gear 54 can mesh with an internal spline formed on the slider 55b.

  In this configuration, as shown in FIGS. 6 to 9, when the slider 55 b is in a position where it does not stick out in the axial direction from the clutch hub 55 a to the auxiliary transmission shaft transmission gear 54, the slider 55 b is connected to the auxiliary transmission shaft transmission gear 54. Since it is not coupled to the fitting portion 54a, the rotation of the auxiliary transmission shaft 50 is not transmitted to the auxiliary transmission shaft transmission gear 54 (and thus the auxiliary transmission shaft third gear 63 and the auxiliary transmission shaft 60). On the other hand, as shown in FIG. 10, when the slider 55b is located across the clutch hub 55a and the fitting portion 54a of the auxiliary transmission shaft transmission gear 54, the clutch hub 55a and the auxiliary transmission shaft transmission gear 54 are interposed via the slider 55b. Therefore, the rotation of the auxiliary transmission shaft 50 is transmitted to the auxiliary transmission shaft transmission gear 54 (and thus the auxiliary transmission shaft third gear 63 and the auxiliary transmission shaft 60).

  The slider 67 b of the auxiliary transmission shifter 67 is attached to the tip of the shift fork 81. Further, the slider 55 b of the auxiliary transmission shaft shifter 55 is attached to the tip of the shift fork 82. The two shift forks 81 and 82 are fixed to a common fork shaft 80. The fork shaft 80 is disposed so as to be parallel to the auxiliary transmission shaft 60 and the auxiliary transmission shaft 50, and is supported so as to be movable with a predetermined stroke in the axial direction.

  When the operator operates the auxiliary transmission lever, the fork shaft 80 can be moved in the axial direction. As a result, the slider 67b of the auxiliary transmission shifter 67 and the slider 55b of the auxiliary transmission shaft shifter 55 move linearly so as to maintain the mutual positional relationship. Since the sliders 67b and 55b are connected to each other through the fork shaft 80 in this way, when the slider 67b of the auxiliary transmission shifter 67 is in the position shown in each of FIGS. 6 to 10, the auxiliary transmission shaft shifter 55 The slider 55b is also in the position shown in each of FIGS.

  Since the sliders 67b and 55b move in association with each other as described above, the slider 67b of the auxiliary transmission shifter 67 is in a position where it does not substantially stick out from the clutch hub 67a in the axial direction as shown in FIG. In some cases, the slider 55b of the sub-transmission shaft shifter 55 is located in a range that does not substantially stick out from the clutch hub 55a formed slightly longer in the axial direction to the sub-transmission shaft transmission gear 54 side. Therefore, in this state, the rotation of the auxiliary transmission shaft 50 is not transmitted to the auxiliary transmission shaft transmission gear 54 (and thus the auxiliary transmission shaft third gear 63 and the auxiliary transmission shaft 60). When the slider 67b of the auxiliary transmission shifter 67 is in a position straddling the clutch hub 67a and the fitting portion 61a of the auxiliary transmission first speed gear 61 (FIG. 7), and when the clutch hub 67a and the auxiliary transmission second speed gear 62 are engaged. The same applies to the position over the joint 62a (FIG. 8).

  On the other hand, as shown in FIG. 10, in the auxiliary transmission shaft shifter 55, when the slider 55b is located between the clutch hub 55a and the fitting portion 54a of the auxiliary transmission shaft transmission gear 54, the slider 67b of the auxiliary transmission shifter 67 is It disengages from the clutch hub 67a and is positioned at a boss portion that is formed slightly longer in the axial direction in the auxiliary transmission second speed gear 62. Accordingly, in this state, neither the rotation of the auxiliary transmission first speed gear 61 nor the rotation of the auxiliary transmission second speed gear 62 is transmitted to the auxiliary transmission shaft 60.

  As described above, the coupling / releasing positions of the sliders 67b and 55b are determined so that both the sub-shift shifter 67 and the sub-transmission shaft shifter 55 do not transmit power simultaneously. A transmission configuration can be realized.

  As shown in FIG. 9, the slider 67b of the auxiliary transmission shifter 67 is disengaged from the clutch hub 67a between the positions of the auxiliary transmission shifter 67 and the auxiliary transmission shaft shifter 55 shown in FIGS. There is a position where the slider 55 b of the transmission shaft shifter 55 is not coupled to the fitting portion 54 a of the sub transmission shaft transmission gear 54. In the state of FIG. 9, the power of the auxiliary transmission shaft 50 is not transmitted to the auxiliary transmission shaft 60 as in the state of FIG. 6.

  Subsequently, the three shift speeds realized in the sub-transmission device 20, that is, the first sub-speed (first state), the second sub-speed (third state), and the third sub-speed (second state). explain.

  First, the power cutoff state will be described. In a state where the operator positions the sub-shift lever at the neutral position, the slider 67b of the sub-shift shifter 67 and the slider 55b of the sub-transmission shaft shifter 55 are at the reference position shown in FIG. In this state, the rotation of the auxiliary transmission shaft 50 is not transmitted to the auxiliary transmission shaft 60.

  In a state where the operator positions the sub-shift lever at the first speed (sub-shift first speed), the slider 67b of the sub-shift shifter 67 and the slider 55b of the sub-transmission shaft shifter 55 are at the positions shown in FIG. As a result, the slider 67 b is positioned so as to straddle the clutch hub 67 a and the fitting portion 61 a of the auxiliary transmission first speed gear 61, and the both are coupled, so that the rotation of the auxiliary transmission first speed gear 61 is transmitted via the auxiliary transmission shifter 67. Is transmitted to the auxiliary transmission shaft 60.

  In a state in which the operator positions the sub-shift lever at the second speed (sub-shift second speed), the slider 67b of the sub-shift shifter 67 and the slider 55b of the sub-transmission shaft shifter 55 are at the positions shown in FIG. As a result, the slider 67b is positioned so as to straddle the clutch hub 67a and the fitting portion 62a of the sub-transmission second speed gear 62, and the both are coupled. Is transmitted to the auxiliary transmission shaft 60.

  In a state where the operator has positioned the sub-shift lever at the third speed (sub-shift third speed), the slider 67b of the sub-shift shifter 67 and the slider 55b of the sub-transmission shaft shifter 55 are at the positions shown in FIG. As a result, the slider 55b is positioned so as to straddle the clutch hub 55a and the fitting portion 54a of the sub-transmission shaft transmission gear 54, and both are coupled to each other, so that the sub-transmission shaft 50 rotates via the sub-transmission shaft shifter 55. It is transmitted to the auxiliary transmission shaft transmission gear 54 (and thus the auxiliary transmission shaft third gear 63 and the auxiliary transmission shaft 60).

  When switching between the sub-speed 2 and the sub-speed 3, the slider 67b of the sub-shift shifter 67 and the slider 55b of the sub-transmission shaft shifter 55 pass through the positions shown in FIG. In the state of FIG. 9, the rotation of the sub transmission shaft 50 is not transmitted to the sub transmission shaft 60.

  Thus, the state of the auxiliary transmission 20 of the present embodiment is such that the fork shaft 80 is moved from one end of the stroke toward the other end to thereby cut off the power corresponding to the first sub-speed (FIG. 7) and neutral. The state is switched in the order of the state (FIG. 6), the sub-speed 2 (FIG. 8), the power cut off state (FIG. 9), and the sub-speed 3 (FIG. 10). As a result, a natural linear shift can be realized.

  Further, in the auxiliary transmission device 20 of the present embodiment, the above configuration can reduce the sliding distance of the shifters (that is, the auxiliary transmission shifter 67 and the auxiliary transmission shaft shifter 55) on the respective shafts, so that a compact configuration is realized. In addition, it is possible to improve the degree of freedom of arrangement of the shifter.

  Depending on the application of the work vehicle and the like, higher speed may be required at the sub-speed 3rd speed (FIG. 10) which is a high speed stage. In order to meet this requirement, it is necessary to enlarge the sub-transmission shaft transmission gear 54 that is the drive-side gear and to reduce the sub-transmission shaft third gear 63 that is the driven gear. In this regard, in the present embodiment, the sub-transmission shaft shifter 55 (switching on the drive side) is provided on the sub-transmission shaft 50 for switching to the sub-speed 3rd speed which is the high speed stage. Therefore, it is not necessary to provide the spline teeth (fitting portion) in the auxiliary transmission shaft third gear 63 that requires a reduction in diameter, and it is only necessary to provide the fitting portion 54a on the auxiliary transmission shaft transmission gear 54 side. Therefore, it is easy to process and the cost can be reduced.

  As described above, the auxiliary transmission 20 of the present embodiment includes the auxiliary transmission shaft 50, the auxiliary transmission shaft 60, the first transmission gear 51, the auxiliary transmission first speed gear 61, and the auxiliary transmission shaft transmission gear 54. An auxiliary transmission shaft third gear 63, an auxiliary transmission shaft shifter 55, an auxiliary transmission shifter 67, and a fork shaft 80. Power from the hydraulic continuously variable transmission 120 is transmitted to the auxiliary transmission shaft 50. The power of the sub transmission shaft 50 is shifted and transmitted to the sub transmission shaft 60. The first transmission gear 51 rotates integrally with the sub transmission shaft 50. The auxiliary transmission first speed gear 61 is engaged with the first transmission gear 51 and is supported by the auxiliary transmission shaft 60 so as to be relatively rotatable. The auxiliary transmission shaft transmission gear 54 is supported by the auxiliary transmission shaft 50 so as to be relatively rotatable. The auxiliary transmission shaft third gear 63 meshes with the auxiliary transmission shaft transmission gear 54 and rotates integrally with the auxiliary transmission shaft 60. The sub transmission shaft shifter 55 is disposed on the sub transmission shaft 50. The auxiliary transmission shifter 67 is disposed on the auxiliary transmission shaft 60. The fork shaft 80 moves the auxiliary transmission shaft shifter 55 and the auxiliary transmission shifter 67 in conjunction with each other. The auxiliary transmission shaft shifter 55 is formed with an internal spline that is not rotatable relative to the auxiliary transmission shaft 50 and is slidable in the axial direction. The auxiliary transmission shifter 67 is formed with an internal spline that is not rotatable relative to the auxiliary transmission shaft 60 and is slidable in the axial direction. The auxiliary transmission first speed gear 61 is formed with a fitting portion 61 a that can mesh with the internal spline of the auxiliary transmission shifter 67. The sub-transmission shaft transmission gear 54 is formed with a fitting portion 54 a that can mesh with the internal spline of the sub-transmission shaft shifter 55. The auxiliary transmission 20 is configured to be switchable between the first sub-speed and the third sub-speed by sliding the fork shaft 80 in the axial direction. At the first sub-speed (FIG. 7), the sub-shift shifter 67 couples the fitting portion 61a of the first sub-speed gear 61 and the sub-transmission shaft 60 so that they cannot rotate relative to each other, and the sub-transmission shaft shifter 55 shifts the sub-transmission shaft. The gear 54 and the sub-transmission shaft 50 are not coupled. At the third sub-speed (FIG. 10), the sub-shift shifter 67 does not couple the sub-speed first gear 61 and the sub-transmission shaft 60, and the sub-transmission shaft shifter 55 is connected to the fitting portion 54 a of the sub-transmission shaft transmission gear 54. The auxiliary transmission shaft 50 is coupled so as not to be relatively rotatable. The third sub-speed is higher than the first sub-speed.

  As a result, the coupling between the sub-transmission first speed gear 61 and the sub-transmission shifter 67 and the coupling of the sub-transmission shaft transmission gear 54 and the sub-transmission shaft shifter 55 are formed on the internal spline of the shifter. Therefore, it is possible to simplify the configuration of each shifter while realizing a linear shift. Even when it is desired to increase the speed at the third speed of the auxiliary transmission, since the fitting portion 54a is formed in the auxiliary transmission shaft transmission gear 54 (which should have a large diameter) on the drive side, the fitting portion is particularly compact. There is no need. Therefore, the reduction ratio setting and the degree of freedom in layout can be increased. By allocating and providing two shifters (sub-shift shifter 67 and sub-transmission shaft shifter 55) on different shafts, the sliding distance of each shifter can be shortened compared to a configuration in which only one shifter is provided. . Accordingly, it is possible to reduce the size of the auxiliary transmission 20 in the axial direction.

  Further, the auxiliary transmission device 20 of the present embodiment includes a second transmission gear 52 and an auxiliary transmission second speed gear 62. The second transmission gear 52 rotates integrally with the sub transmission shaft 50. The auxiliary transmission second speed gear 62 meshes with the second transmission gear 52 and is supported by the auxiliary transmission shaft 60 so as to be relatively rotatable. A fitting portion 62 a that can mesh with the internal spline of the auxiliary transmission shifter 67 is formed in the auxiliary transmission second speed gear 62. The auxiliary transmission 20 slides the fork shaft 80 in the axial direction, so that the auxiliary transmission shifter 67 couples the fitting portion 62a of the auxiliary transmission second gear 62 and the auxiliary transmission shaft 60 so as not to rotate relative to each other. The shaft shifter 55 is configured to be switchable to the second sub-speed (FIG. 8) in which the sub-transmission shaft transmission gear 54 and the sub-transmission shaft 50 are not coupled.

  As a result, speed stage switching of three or more stages can be realized by linear shift. In addition, the configuration of each shifter (sub-shift shifter 67 and sub-transmission shaft shifter 55) is simplified compared to a configuration that realizes three-speed speed switching by providing a shifter and gear part on one shaft. Therefore, parts can be easily manufactured, and costs can be reduced.

  Further, the auxiliary transmission 20 according to the present embodiment slides the fork shaft 80 in the axial direction, so that the auxiliary transmission 1st speed, The speed is switched between the sub-speed 3 and the sub-speed 2.

  As a result, a natural auxiliary transmission operation can be performed.

  Next, a second embodiment will be described with reference to FIG. FIG. 11 is a developed cross-sectional view showing a power cut-off state in which the sub-transmission shaft shifter 55 and the sub-transmission shifter 67 are at the reference position and no power is transmitted in the sub-transmission device 20x of the second embodiment. In the description of the present embodiment, the same or similar members as those of the above-described embodiment may be denoted by the same reference numerals in the drawings, and description thereof may be omitted.

  In the auxiliary transmission device 20x of this embodiment shown in FIG. 11, gears are arranged on both sides in the axial direction of the auxiliary transmission shaft shifter 55 arranged on the auxiliary transmission shaft 50, and an auxiliary transmission shifter 67 arranged on the auxiliary transmission shaft 60. A gear is disposed only on one side in the axial direction.

  Specifically, the sub-transmission shaft shift gear 54 is disposed on one side of the sub-transmission shaft shifter 55 in the axial direction, and the sub-transmission shaft second transmission gear (second output gear) 57 is disposed on the other side. The sub-transmission shaft second transmission gear 57 is supported so as to be rotatable relative to the sub-transmission shaft 50 in the same manner as the sub-transmission shaft transmission gear 54. An auxiliary transmission second speed gear (second input gear) 68 is fixed to the auxiliary transmission shaft 60, and the auxiliary transmission shaft second transmission gear 57 meshes with the auxiliary transmission second speed gear 68. The auxiliary transmission shaft second transmission gear 57 is formed with a boss portion protruding so as to approach the clutch hub 55a of the auxiliary transmission shaft shifter 55. On the outer peripheral surface of the boss portion, a fitting portion 57a made of spline teeth that can mesh with an internal spline formed on the slider 55b of the sub-transmission shaft shifter 55 is formed.

  On the other hand, the sub-transmission second speed gear 62 arranged on the one axial side of the sub-transmission shifter 67 in the first embodiment is omitted in this embodiment.

  In the present embodiment, the slider 67 b of the auxiliary transmission shifter 67 is coupled to the auxiliary transmission first speed gear 61 to achieve the first auxiliary transmission speed, and the slider 55 b of the auxiliary transmission shaft shifter 55 is coupled to the auxiliary transmission shaft second transmission gear 57. As a result, the sub-transmission second speed is obtained, and the slider 55b of the sub-transmission shaft shifter 55 is coupled to the sub-transmission shaft transmission gear 54 to obtain the sub transmission third speed. As described above, even in the configuration of the present embodiment, the auxiliary transmission shifter 67 and the auxiliary transmission shaft shifter 55 are moved in conjunction with each other via the fork shaft 80, thereby realizing a three-stage auxiliary transmission.

  As described above, the auxiliary transmission 20x of the present embodiment includes the auxiliary transmission shaft second transmission gear 57 and the auxiliary transmission second speed gear 68. The sub transmission shaft second transmission gear 57 is supported by the sub transmission shaft 50 so as to be relatively rotatable. The auxiliary transmission second speed gear 68 meshes with the auxiliary transmission shaft second transmission gear 57 and rotates integrally with the auxiliary transmission shaft 60. The auxiliary transmission shaft second transmission gear 57 is formed with a fitting portion 57 a that can mesh with the internal spline of the auxiliary transmission shaft shifter 55. In the auxiliary transmission device 20x, by sliding the fork shaft 80 in the axial direction, the auxiliary transmission shaft shifter 55 is coupled to the fitting portion 57a of the auxiliary transmission shaft second transmission gear 57, and the auxiliary transmission shifter 67 is connected to the first speed of the auxiliary transmission. The gear 61 and the sub-transmission shaft 60 are configured to be switchable to the second sub-speed that does not couple.

  As a result, speed stage switching of three or more stages can be realized by linear shift. In addition, the shifter configuration is simplified by providing shifter-and-gear parts on a single shaft, compared to a configuration that achieves three-stage speed stage switching. Can be planned.

  Although the preferred embodiment of the present invention has been described above, the above configuration can be changed as follows, for example.

  In the two embodiments described above, a gear is provided on one side of one of the two shifters, and a gear is provided on both sides of the other shifter, thereby realizing three-stage speed stage switching. Instead of this, any of the two shifters can be configured such that gears are provided on both sides and the four speed stages are switched.

  In the above embodiment, the auxiliary transmission 20 of the present embodiment is configured to switch from the low speed to the high speed in order by sliding the fork shaft 80 from the rear side toward the front side. Instead, the fork shaft 80 may be slid from the front side toward the rear side so as to be switched from low speed to high speed in order.

  In the above embodiment, the first transmission gear 51, the second transmission gear 52, the auxiliary transmission shaft third gear 63, the auxiliary transmission second speed gear 68 and the like are configured as separate members fixed to the shaft. Instead, these gears may be formed integrally with the auxiliary transmission shaft 50 or the auxiliary transmission shaft 60.

  The auxiliary transmission operating tool for operating the fork shaft 80 is not limited to a lever.

  The main transmission can be configured as a gear-type transmission instead of the hydraulic continuously variable transmission 120 as in the above embodiment.

  The present invention is not limited to a tractor and can be applied to various work vehicles such as a rice transplanter, a combiner, and a wheel loader.

20, 20x Sub transmission 50 Sub transmission shaft (Transmission shaft)
51 First transmission gear (first output gear)
52 Second transmission gear (third output gear)
54 Sub-transmission shaft transmission gear (second output gear)
54a Fitting part 55 Sub transmission shaft shifter (transmission shaft shifter)
57 Sub-transmission shaft second transmission gear (third output gear)
57a Fitting part 60 Subtransmission shaft 61 Subtransmission first speed gear (first input gear)
61a Fitting portion 62 Sub-speed second gear (third input gear)
62a Fitting part 63 Sub-transmission shaft third gear (second input gear)
67 Sub-shift shifter 68 Sub-speed second gear (second input gear)
80 Fork shaft 100 Tractor (work vehicle)
120 hydraulic continuously variable transmission (main transmission)

Claims (5)

A transmission shaft to which power from the main transmission is transmitted;
A sub-transmission shaft through which the power of the transmission shaft is shifted and transmitted;
A first output gear that rotates integrally with the transmission shaft;
A first input gear that meshes with the first output gear and that is rotatably supported by the auxiliary transmission shaft;
A second output gear supported by the transmission shaft so as to be relatively rotatable;
A second input gear meshing with the second output gear and rotating integrally with the auxiliary transmission shaft;
A transmission shaft shifter disposed on the transmission shaft;
A sub-shift shifter disposed on the sub-transmission shaft;
A fork shaft that moves the transmission shaft shifter and the auxiliary transmission shifter in conjunction with each other;
With
The transmission shaft shifter is formed with an internal spline that is not rotatable relative to the transmission shaft and is slidable in the axial direction.
The sub-shift shifter is formed with an internal spline that is not rotatable relative to the sub-transmission shaft and is slidable in the axial direction.
The first input gear is formed with a fitting portion that can mesh with the internal spline of the auxiliary transmission shifter,
The second output gear is formed with a fitting portion that can mesh with the internal spline of the transmission shaft shifter,
By sliding the fork shaft in the axial direction,
A first state in which the auxiliary transmission shifter couples the fitting portion of the first input gear and the auxiliary transmission shaft so as not to rotate relative to each other, and the transmission shaft shifter does not couple the second output gear and the transmission shaft. When,
The auxiliary transmission shifter does not couple the first input gear and the auxiliary transmission shaft, and the transmission shaft shifter couples the fitting portion of the second output gear and the transmission shaft so as not to be relatively rotatable. State and
Can be switched between,
The secondary transmission is characterized in that the second state is a higher speed stage than the first state. The auxiliary transmission device according to claim 1,
A third output gear that rotates integrally with the transmission shaft;
A third input gear meshing with the third output gear and supported by the auxiliary transmission shaft so as to be relatively rotatable;
With
The third input gear is formed with a fitting portion that can mesh with the internal spline of the auxiliary transmission shifter,
By sliding the fork shaft in the axial direction, the auxiliary transmission shifter couples the fitting portion of the third input gear and the auxiliary transmission shaft so that they cannot rotate relative to each other, and the transmission shaft shifter outputs the second output. A sub-transmission device configured to be switchable to a third state in which the gear and the transmission shaft are not coupled. The auxiliary transmission device according to claim 1,
A third output gear supported by the transmission shaft so as to be relatively rotatable;
A third input gear meshing with the third output gear and rotating integrally with the auxiliary transmission shaft;
With
The third output gear is formed with a fitting portion that can mesh with the internal spline of the transmission shaft shifter,
By sliding the fork shaft in the axial direction, the transmission shaft shifter couples the fitting portion of the third output gear and the transmission shaft so as not to rotate relative to each other, and the auxiliary transmission shifter connects the first input gear. And a subtransmission device configured to be switchable to a third state in which the subtransmission shaft is not coupled. The auxiliary transmission device according to claim 2 or 3,
The sub-shift is characterized by being switched between the first state, the second state, and the third state so that the fork shaft is slid in the axial direction so as to be in a high speed stage sequentially from one side. apparatus.   A work vehicle comprising the auxiliary transmission device according to any one of claims 1 to 4.

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