JP2008180255A - Working vehicle transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, although desires are increased to improve the driving operability and travelling stability of a working vehicle such as a tractor when travelling to be moved at a high speed on a road, troublesome shifting operation itself still cannot be eliminated using conventional technology and the driving operability remains poor. <P>SOLUTION: This working vehicle transmission mechanism having shift control construction comprises a torque converter 4 provided between an engine 2 and a gear type transmission device 33. Herein, there are provided a high speed travel mode for transmitting engine power via the torque converter 4 to the gear type transmission device 33 to perform shifting operation, and a working travel mode for transmitting engine power directly to the gear type transmission device 33 to perform shifting operation. In one of the working travel mode and the high speed travel mode, speed stages of the gear type transmission device 33, and a high speed stage, a low speed stage and a creeping stage of a sub transmission device 9, e.g., can be set. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a work vehicle transmission mechanism including a stepped transmission that shifts engine power output from an engine and transmits the engine power to an axle.

In a conventional transmission mechanism for a work vehicle, two clutches are provided in a stepped transmission, and the separation operation of one clutch overlaps with the engagement operation of the other clutch while the shifting operation is being performed. A technique is known in which a double transmission state is generated and a running speed is continuously changed without interrupting power transmission from the engine to the axle (see, for example, Patent Document 1).
JP 2003-314679 A

  Currently, in the case of a work vehicle such as a tractor, in order to shorten the travel time for moving to the next work place and to make efficient use of the work vehicle, driving operation when traveling on the road at high speed for movement There is an increasing demand for improved performance and running stability. On the other hand, although the above-mentioned speed change mechanism for work vehicles can reduce the shock caused by the speed change, smooth acceleration and speed change is difficult as in a general passenger car, and good driving operability and running stability cannot always be obtained. There was a problem.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
In other words, in claim 1, in a work vehicle transmission mechanism including a stepped transmission that shifts engine power output from an engine and transmits the engine power to an axle, between the engine and the stepped transmission. A high speed travel mode is provided in which a torque converter is provided and engine power is transmitted to the stepped transmission via the torque converter to perform a shift, and the engine power is directly transmitted to the stepped transmission to perform a shift. A work control mode is provided, and a shift control configuration is provided in which each speed stage of the stepped transmission can be set in one of the work drive mode and the high-speed drive mode.
According to a second aspect of the present invention, the torque converter is provided with a lockup mechanism that directly transmits engine power to the stepped transmission.
According to a third aspect of the present invention, the stepped transmission is provided with a low-speed gear train for starting to be used when starting the work vehicle, and the low-speed gear train is selected when starting.
According to a fourth aspect of the present invention, the stepped transmission includes a first clutch for connecting / disconnecting power to an odd-numbered shift drive train, and a second clutch for connecting / disconnecting power to an even-numbered shift drive train. A main transmission device that temporally overlaps one of the first clutch and the second clutch with the other of the joint operations in a state where the shift drive trains of the odd and even stages are selected. Is provided.
According to a fifth aspect of the present invention, the stepped transmission is provided with a sub-transmission that shifts the main transmission power from the main transmission to a plurality of sub-speed stages, and the high-speed traveling mode is selected when each sub-speed stage is selected. And switching means for automatically assigning to a predetermined traveling mode among the working traveling modes.
According to a sixth aspect of the present invention, a forward / reverse switching device that switches the traveling direction back and forth is disposed on the lower transmission side of the torque converter, and the first clutch and the second clutch are disposed on the lower transmission side of the forward / backward switching device. It is to be arranged.
According to a seventh aspect of the present invention, the first clutch and the second clutch are disposed back to back on a common transmission shaft.
According to another aspect of the present invention, the work vehicle transmission mechanism includes a PTO transmission that shifts engine power and transmits the engine power to the PTO shaft. The engine power is directly transmitted to the PTO transmission without passing through the torque converter. To do.

Since this invention was comprised as mentioned above, there exists an effect shown below.
In other words, in claim 1, in a work vehicle transmission mechanism including a stepped transmission that shifts engine power output from an engine and transmits the engine power to an axle, between the engine and the stepped transmission. A high speed travel mode is provided in which a torque converter is provided and engine power is transmitted to the stepped transmission via the torque converter to perform a shift, and the engine power is directly transmitted to the stepped transmission to perform a shift. Since the operation mode is provided and a shift control configuration is provided in which each speed stage of the stepped transmission can be set to one of the work mode and the high speed mode. If the speed stage of the transmission is set to the high-speed running mode, once the speed stage is set, the torque is automatically changed to a torque suitable for high-speed running by the torque converter. Can, sufficient driving operability and running stability can be obtained by performing the acceleration and speed in very smooth. On the other hand, when the speed stage of the stepped transmission is set to the working travel mode, the speed is changed only by the stepped transmission, so that the torque greatly fluctuates by traveling on a soft field with a large traveling resistance. However, it is possible to work at a constant speed, and furthermore, power transmission loss can be suppressed smaller than when using a torque converter with fluid, and high work efficiency is ensured by stabilizing work speed and improving power transmission efficiency. be able to.
According to a second aspect of the present invention, since the torque converter is provided with a lockup mechanism that directly transmits engine power to the stepped transmission, a special bypass transmission is performed by a clutch engagement operation of the lockup clutch of the lockup mechanism. Engine power can be directly transmitted to the stepped transmission without providing a separate path, and the number of parts can be reduced to reduce parts costs, make the speed change mechanism more compact, and improve maintainability. it can.
According to a third aspect of the present invention, the stepped transmission is provided with a low-speed gear train for starting that is used when starting the work vehicle, and the low-speed gear train is selected at the time of starting. Even when traveling with engine power output without intervention, by using this low-speed gear train for starting, the work vehicle can be started reliably without causing an engine stall, and stable starting is always possible. Performance can be obtained. Furthermore, since the vehicle starts using the low-speed gear train, the load at the time of starting is reduced, and sufficient durability can be obtained even with a small clutch pack.
According to a fourth aspect of the present invention, the stepped transmission includes a first clutch for connecting / disconnecting power to an odd-numbered shift drive train, and a second clutch for connecting / disconnecting power to an even-numbered shift drive train. A main transmission device that temporally overlaps one of the first clutch and the second clutch with the other of the joint operations in a state where the shift drive trains of the odd and even stages are selected. Therefore, it is possible to continuously shift gears without interrupting the transmission of power from the engine to the axle, further improving driving operability and driving stability compared to the case of using a normal stepped transmission. Can be improved.
According to a fifth aspect of the present invention, the stepped transmission is provided with a sub-transmission that shifts the main transmission power from the main transmission to a plurality of sub-speed stages, and the high-speed traveling mode is selected when each sub-speed stage is selected. And switching means that automatically assigns to a predetermined traveling mode among the working traveling modes, the traveling mode can be set to any one in conjunction with the selection of the sub-speed stage, and the speed can be set with a work vehicle such as a tractor. This makes it possible to simplify the operation of selecting the travel mode, which tends to be complicated when there are many stages, and to improve the shift operability.
According to a sixth aspect of the present invention, a forward / reverse switching device that switches the traveling direction back and forth is disposed on the lower transmission side of the torque converter, and the first clutch and the second clutch are disposed on the lower transmission side of the forward / backward switching device. Because it is installed, forward / reverse switching is performed on the output shaft from the torque converter or on the transmission shaft near it, greatly reducing power transmission loss during forward / reverse switching with large torque fluctuations, and power transmission efficiency In addition, the forward / reverse switching device and the first clutch / second clutch can be placed close to each other to reduce the space required for the installation, and the transmission mechanism can be made compact.
In claim 7, since the first clutch and the second clutch are arranged back to back on a common transmission shaft, the clutch arrangement is different from the case where each clutch is arranged separately as usual. Therefore, it is possible to reduce the space for the clutch and to make the clutch parts common, thereby further reducing the cost of the parts and making the speed change mechanism compact.
According to another aspect of the present invention, the work vehicle transmission mechanism includes a PTO transmission that shifts engine power and transmits the engine power to the PTO shaft. The engine power is directly transmitted to the PTO transmission without passing through the torque converter. Therefore, it is possible to always transmit the engine power directly to the PTO shaft and drive it at a constant speed in any travel mode, and to bypass the engine power directly to the PTO shaft even in the work travel mode. There is no need to provide a separate transmission path, and the lock-up mechanism can be downsized by the amount that connection and disconnection of the transmission power to the PTO shaft is no longer required, reducing component costs and downsizing the speed change mechanism. Thus, it is possible to improve the maintainability.

Next, embodiments of the invention will be described.
1 is a skeleton diagram showing an overall configuration of a work vehicle according to a first embodiment of the present invention, FIG. 2 is a partial plan view of a plane of a main transmission of the first embodiment, and FIG. 3 is a gear shift operation and clutch operation of the first embodiment. 4 is a block diagram, FIG. 5 is an explanatory diagram of the clutch engagement structure, FIG. 5 (a) is a side sectional view of the engagement portion, and FIG. FIG. 6 is a skeleton diagram showing the overall configuration of the work vehicle according to the second embodiment of the present invention, FIG. 7 is a partial plan view of the main transmission of the second embodiment, and FIG. Fig. 9 is a block diagram, Fig. 10 is an explanatory diagram showing a gear train used at the time of starting, and Fig. 11 is an overall work vehicle according to another embodiment of the second embodiment. It is a skeleton figure which shows a structure. In addition, let the downward direction in FIG.1, FIG.6, FIG.11 be a body front.

The overall configuration of the work vehicle 1 according to the first embodiment of the present invention will be described with reference to FIG.
The work vehicle 1 is a four-wheel drive agricultural tractor, and includes an engine 2 and a gear-type transmission 33 that changes rotational power (hereinafter referred to as “engine power”) from the engine 2. Yes. The crankshaft 40 of the engine 2 is connected to the input shaft 3, and a cylindrical output shaft 5 is externally fitted to the input shaft 3 so as to be relatively rotatable, and between the output shaft 5 and the input shaft 3. Is provided with a torque converter 4 with a lock-up mechanism so that the engine power is output to the gear transmission 33 via the input shaft 3, torque converter 4 and output shaft 5. Yes.

  Here, in the torque converter 4, the input shaft 3 is fixed to the front cover 34, the pump impeller 35 is connected to the front cover 34, the output shaft 5 is connected to the turbine runner 36, and the transmission A stator 37 is supported on the front portion of the case 23 via a one-way clutch 38. A lockup clutch 39 is disposed between the front cover 34 and the turbine runner 36. The connection state between the input shaft 3 and the output shaft 5 is changed by a lockup mechanism 80, which will be described later, including the lockup clutch 39 and the like.

  Further, the input shaft 3 fixed to the front cover 34 is directly extended into the transmission case 23, and a hydraulic multi-plate friction type PTO clutch 10 is provided at the extended end thereof. The input shaft 3 is connected to a transmission shaft 11 having a small-diameter gear 12 fixed thereto. A PTO shaft 14 is provided in parallel to the transmission shaft 11, and a large-diameter gear 13 fixed on the PTO shaft 14 meshes with the small-diameter gear 12 to constitute a PTO transmission 6 for deceleration. The PTO transmission 6 decelerates the engine power via the input shaft 3, the PTO clutch 10, and the PTO transmission 6 so that it can be connected and disconnected, and is transmitted to the PTO shaft 14.

  The output shaft 5 is connected to the sub-transmission output shaft 19 via a gear-type transmission 33 including a forward / reverse switching device 7, a main transmission 8, and a sub-transmission 9 connected in the mission case 23. After the rotational direction and speed of the engine are switched, the engine power is transmitted to the sub-transmission output shaft 19 as transmission power. The auxiliary transmission output shaft 19 has a bevel gear 24 fixed at the rear end thereof, and a side gear 41 fixed on the transmission shafts 27 and 27 and both of the side gear 41 in the differential gear 26 integrated with the bull gear 25 meshing with the bevel gear 24. The left and right transmission shafts 27 and 27 are fitted through a bevel gear clutch mechanism 28 constituted by a bevel pinion 42 meshing with the side gear 41 to form a differential gear device 43. Further, left and right rear axles 32, 32 are connected to the outer ends of the transmission shafts 27, 27 via a speed reducer 31, and rear wheels 21, 21 are fixed to the outer ends of the rear axles 32, 32. ing. Thereby, the rotation input to the bull gear 25 from the auxiliary transmission output shaft 19 via the bevel gear 24 is transmitted from the rear axles 32 and 32 to the rear wheels 21 and 21 as a differential rotation.

  The differential gear device 43 is provided with a differential lock mechanism 44 for locking the differential rotation. In the differential lock mechanism 44, a differential lock slider 45 that is spline-fitted to the boss portion of the differential cage 26 is provided. A differential lock pin 46 is provided, and the differential lock pin 46 is engaged with a pin hole drilled in the side gear 41 by a sliding operation of the differential lock slider 45, so that the differential lock is achieved, thereby improving the straightness and the runnability in the muddy state. I have to. Similarly, transmission power from the auxiliary transmission output shaft 19 is transmitted to a front wheel (not shown) through a mechanism such as a differential gear device or a reduction gear (not shown).

  As described above, the transmission power is transmitted to the front and rear wheels, and various operations can be performed by a working machine (not shown) connected and interlocked with the PTO shaft 14 while traveling by the front and rear wheels.

Next, the gear transmission 33 will be described with reference to FIGS. 1 to 3 and FIG.
In the transmission case 23, the clutch input shaft 15, the first traveling transmission shaft 16, the second traveling transmission shaft 17, and the main transmission output shaft 18 are parallel to the output shaft 5 and the auxiliary transmission output shaft 19. It is horizontally mounted so that it can rotate.

  A forward drive gear 47 and a reverse drive gear 48 having the same diameter are fixed on the output shaft 5 in order from the rear. The clutch input shaft 15 is disposed on the left side of the output shaft 5, and the forward driven gear 49 and the reverse driven gear 50 are provided on the clutch input shaft 15 so as to be relatively rotatable in order from the rear. Of these, the forward driven gear 49 is meshed with the forward drive gear 47, and the reverse driven gear 50 is meshed with an idle gear 53 on an intermediate shaft 52 provided in the longitudinal direction of the machine body. 53 is meshed with the reverse drive gear 48.

  Further, on the clutch input shaft 15, a spline hub 54 is engaged between the forward driven gear 49 and the reverse driven gear 50 so as not to be relatively rotatable, and a shifter 54 a is disposed on the spline hub 54. Clutch tooth portions 49a and 50a are formed in the forward and backward driven gears 49 and 50 toward the spline hub 54, respectively, so as to be slidable in the direction and not relatively rotatable. A switching device 7 is formed.

  Accordingly, by engaging the clutch tooth portions 49a and 50a with the shifter 54a, the corresponding driven gear can be engaged with the clutch input shaft 15 so as not to be relatively rotatable, and the output shaft 5 can be engaged with the clutch input shaft. 15 can transmit forward power or reverse power.

  The first traveling speed change shaft 16 is disposed on the right side of the output shaft 5, and the second traveling speed change shaft 17 is disposed on the left side of the clutch input shaft 15. A frictional multi-plate type first clutch 55 and a second clutch 56 are respectively disposed on the second travel transmission shaft 17. A first clutch input gear 57 is rotatably provided behind the first clutch 55 on the first traveling speed change shaft 16. When the first clutch 55 is engaged, the first clutch input gear 57 is The first clutch 55 is engaged with the first travel transmission shaft 16 through the first clutch 55 so as not to be relatively rotatable. A first clutch hydraulic cylinder 59 is provided for this clutch on / off.

  Similarly, a second clutch input gear 58 is rotatably provided behind the second clutch 56 on the second travel transmission shaft 17. When the second clutch 56 is engaged, the second clutch input gear 58 is The second clutch 56 is engaged with the second travel transmission shaft 17 through the second clutch 56 so as not to be relatively rotatable. A second clutch hydraulic cylinder 60 is provided to turn the clutch on and off. The first clutch hydraulic cylinder 59 and the second clutch hydraulic cylinder 60 gradually and continuously change the transmission torque from the disengaged state to the engaged state of the first clutch 55 and the second clutch 56 as described later. It is possible to let you. Further, both the first clutch input gear 57 and the second clutch input gear 58 are always meshed with the branch gear 51 fixed on the clutch input shaft 15 behind the forward driven gear 49.

  As a result, when the first clutch 55 and the second clutch 56 are turned on and off, either of the traveling speed change shafts 16 and 17 selected by the turning on and off is transmitted to the forward power from the clutch input shaft 15. The reverse power can be transmitted.

  That is, as described above, the forward / reverse switching device 7 that switches the traveling direction back and forth is disposed on the lower transmission side of the torque converter 4, and the first clutch 55 is disposed on the lower transmission side of the forward / backward switching device 7. And the second clutch 56 are arranged so that the forward / reverse switching is performed on the clutch input shaft 15, which is a transmission shaft near the output shaft 5 from the torque converter 4, and the power transmission loss due to the forward / reverse switching accompanied by a large torque fluctuation. The transmission / reverse switching device 7 and the first clutch 55 and the second clutch 56 are placed close to each other to reduce the space required for the installation, and the speed change can be achieved. The mechanism can be made compact.

  The space in the transmission case 23 is partitioned by a front first chamber 71 with a bearing wall 69 therebetween, a rear second chamber 72, and a rear third chamber 73 with a bearing wall 70 in between. The forward / reverse switching device 7, the first clutch 55, the second clutch 56, and the like are disposed in the first chamber 71, and the main transmission 8 is disposed in the second chamber 72.

  In the main transmission 8, the first speed drive gear 61, the third speed drive gear 63, the fifth speed drive gear 65, and the seventh speed are arranged in order from the front on a portion of the first traveling speed change shaft 16 that is separated from the bearing wall 69. A drive gear 67 is provided so as to be relatively rotatable, and the second speed drive gear 62, the fourth speed drive gears 64, 6 are also arranged in order from the front on the portion of the second travel transmission shaft 17 that is separated from the bearing wall 69. A high-speed drive gear 66 and an 8-speed drive gear 68 are provided so as to be relatively rotatable. Of these, the first speed driving gear 61 and the second speed driving gear 62, the third speed driving gear 63 and the fourth speed driving gear 64, the fifth speed driving gear 65 and the sixth speed driving gear 66, the seventh speed driving gear 67 and the eighth speed driving gear 68 are included. Are meshed with the first gear 81, the second gear 82, the third gear 83, and the fourth gear 84 on the main transmission output shaft 18, respectively. As a result, a first gear train comprising gears 61 and 81, a second gear train comprising gears 62 and 81, a third gear train comprising gears 63 and 82, a fourth gear train comprising gears 64 and 82, and a gear 65 A plurality of main transmission drive trains are formed, such as a 5-speed gear train consisting of 83, a 6-speed gear train consisting of gears 66 and 83, a 7-speed gear train consisting of gears 67 and 84, and an 8-speed gear train consisting of gears 68 and 84. Has been.

  Further, on the first travel transmission shaft 16, a spline hub 91 is provided between the first speed drive gear 61 and the third speed drive gear 63, and between the second speed drive gear 62 and the fourth speed drive gear 64. Includes a spline hub 92, a spline hub 93 between the fifth speed drive gear 65 and the seventh speed drive gear 67, a spline hub 94 between the sixth speed drive gear 66 and the eighth speed drive gear 68, Each is engaged so as not to be relatively rotatable. Of these, a shifter 91a is provided for the spline hub 91, a shifter 92a is provided for the spline hub 92, a shifter 93a is provided for the spline hub 93, and a shifter 94a is provided for the spline hub 94 to be slidable in the axial direction and relatively rotated. Engaged impossible.

  Clutch tooth portions 61a and 63a are formed in the first and third speed drive gears 61 and 63 toward the spline hub 91, respectively, and the spline hub 92 is formed by the second and fourth speed drive gears 62 and 64, respectively. Clutch tooth portions 62a and 64a are formed in the portion toward the side, respectively, and clutch tooth portions 65a and 67a are formed in the portions toward the spline hub 93 side in the fifth and seventh speed drive gears 65 and 67, respectively. Clutch tooth portions 66a and 68a are formed at portions of the 6th and 8th drive gears 66 and 68 toward the spline hub 94, respectively.

  As a result, the clutch tooth portions 61a, 63a, 65a, and 67a are engaged with any one of the shifters 91a and 93a so that the corresponding drive gear is engaged with the first travel speed change shaft 16 so as not to be relatively rotatable. On the other hand, by engaging the clutch tooth portions 62a, 64a, 66a, 68a with one of the shifters 92a, 94a, the corresponding drive gear is engaged with the second travel transmission shaft 17 so as not to be relatively rotatable. The forward drive power or the reverse drive power that has been transmitted to the travel transmission shafts 16 and 17 is shifted from the first gear to the eighth gear by the main transmission drive trains, and then the main transmission output as the main transmission power. It can be transmitted to the shaft 18.

  Here, an engagement configuration between the dogs formed on the sleeve inner surfaces of the shifters 91a to 94a and the dogs formed on the clutch tooth portions 61a to 68a will be described. In addition, since any engagement structure is the same, the shifter 92a and the clutch tooth part 62a are demonstrated here. As shown in FIG. 5, the dog 92b of the shifter 92a engages with the dog 62b of the clutch tooth portion 62a, whereby the second-speed drive gear 62 is moved from the clutch tooth portion 62a through the shifter 92a and the spline hub 92. The dog 92b of the shifter 92a and the dog 62b of the clutch tooth portion 62a that are adjacent to each other are coupled to the two-travel transmission shaft 17, and are configured to have a large gap 166. Thus, even if the dog 92b slides in the direction of the arrow 167 toward the dog 62b, the dog 92b and the dog 62b are not likely to collide with each other.

  That is, in the main transmission 8, a dog 92b, which is a concavo-convex portion, is formed on the inner surface of the shifter 92a on the spline hub 92 that switches the shift drive train, and the second speed drive that is a gear that engages the shifter 92a The dog 62b, which is an uneven portion, is formed on the outer surface of the clutch tooth portion 62a of the gear 62, and the adjacent dogs 62b and 92b are spaced apart from each other in the circumferential direction. The conventional synchronizer is provided with a chamfer that is a beveled chamfer at the tip of the dog and guides the chamfer while engaging the shifter and the clutch. There is no need to provide a separate gap between the teeth and the frictional heat generated at the time of engagement by the synchronizer can be eliminated to extend the life of each component. And it can be simplified and the cost can be reduced by size and number of parts reduction of the main transmission device 8.

  Further, the rear portion of the main transmission output shaft 18 passes through the bearing wall 70 and protrudes into the third chamber 73 and is connected to the auxiliary transmission device 9. In the auxiliary transmission device 9, a bottom surface portion of a cylindrical high-speed shaft 74 having one end opened is fixed to the rear end portion of the transmission output shaft 18. The front end of the speed change output shaft 19 is pivotally supported. On the auxiliary transmission output shaft 19, a low-speed gear 75 that is used at a low speed during work and a creep gear 76 that is used at a slower, low-speed are provided in an order from the front so as to be relatively rotatable.

  Here, a cylindrical sub-transmission shaft 78 is fitted on the middle portion of the input shaft 3 so as to be relatively rotatable, and a large-diameter gear 85 and a medium-diameter are sequentially arranged on the sub-transmission shaft 78 from the front. A gear 86 and a small-diameter gear 87 are annularly fixed, and the large-diameter gear 85 is meshed with a gear 77 that is circularly fixed to the front portion of the high-speed shaft 74, and the medium-diameter gear 86 is the low-speed gear 75. The small-diameter gear 87 is connected to the creep gear 76 via a speed reducer 79. Thus, as will be described later, the main transmission output shaft 18 is composed of a high-speed gear train composed of a high-speed shaft 74 that can be directly connected to the sub-transmission output shaft 19, a gear 77, a large diameter gear 85, a medium diameter gear 86, and a low speed gear 75. A plurality of auxiliary transmission drive trains such as a low-speed gear train, a creep gear train comprising a gear 77, a large-diameter gear 85, a small-diameter gear 87, a reduction gear 79, and a creep gear 76 are formed.

  Further, on the auxiliary transmission output shaft 19, the spline hub 88 is not rotatable between the high speed shaft 74 and the low speed gear 75, and the spline hub 89 is not relatively rotatable between the low speed gear 75 and the creep gear 76. Is engaged. Of these, a shifter 88a is engaged with the spline hub 88, and a shifter 89a is engaged with the spline hub 89 so as to be slidable in the axial direction and not relatively rotatable. Then, clutch tooth portions 74a and 75a are formed at portions of the high speed shaft 74 and the low speed gear 75 toward the spline hub 88, respectively, and clutch tooth portions 76a are formed at a portion of the creep gear 76 toward the spline hub 89. Has been.

  Thus, by engaging the clutch tooth portions 74a, 75a, and 76a with any one of the shifters 88a and 88a, the corresponding shaft and gear can be engaged with the auxiliary transmission output shaft 19 so as not to be relatively rotatable. The main transmission power transmitted to the main transmission output shaft 18 can be transmitted to the auxiliary transmission output shaft 19 as auxiliary transmission power after being shifted to the high speed, low speed, and creep stages by each of the auxiliary transmission drive trains. I have to. As described above, the auxiliary transmission power is transmitted to each axle via the differential gear device 43 and the speed reduction device 31 to drive the front and rear wheels to travel.

Next, the shifter and clutch operating mechanism and its control in the main transmission 8 of the gear type transmission 33 will be described with reference to FIGS.
The shifters 91a, 92a, 93a, and 94a are engaged with the front portions of the first fork 101, the second fork 102, the third fork 103, and the fourth fork 104, respectively. A shifter shaft 90 is inserted and fixed to each boss portion of the third fork 103 and the fourth fork 104 base. The shifter shaft 90 is inserted between the front and rear bearing walls 96 and 97 projecting from the shifter case 95 of the transmission case 23 so as to be slidable back and forth in parallel with each other, and is arranged in parallel in the horizontal direction. The first fork 101, the second fork 102, the third fork 103, and the fourth fork 104 are integrated with each shifter shaft 90, and are moved in the longitudinal direction of the machine body while being guided.

  As a result, when the shifter shaft 90 is slid, the first fork 101 moves the shifter 91a, and the shifter 91a engages one of the drive gears 61 and 63 with the spline hub 91. One gear train can be selected from among the odd-numbered gear trains composed of the first gear including 61 and the third gear including the drive gear 63. Similarly, when the shifter 92 a is moved by the second fork 102, the shifter 92 a engages either the drive gear 62 or 64 with the spline hub 92, and the second speed including the drive gear 62 and the drive gear 64 are engaged. One gear train can be selected from among the even-numbered gear trains including the fourth speed including the gears. When the shifter 93a is moved by the third fork 103, the shifter 93a is driven to the spline hub 93 by a drive gear. 65 or 67 can be engaged, and one gear train can be selected from among the odd-numbered gear trains consisting of the fifth gear including the drive gear 65 and the seventh gear including the drive gear 67. When the shifter 94a is moved by the fourth fork 104, the shifter 94a engages one of the drive gears 66 and 68 with respect to the spline hub 94, and includes the drive gear 66. Among the gear train of the even stages consisting of 8-speed including a drive gear 68 and, it is possible to select one of the gear train.

  Further, in the shifter case 95, a first hydraulic cylinder 111, a second hydraulic cylinder 112, a third hydraulic cylinder 113, and a fourth hydraulic cylinder 114 are arranged in parallel in the longitudinal direction of the machine body. The connecting arm 105 is projected from one end of each rod 115 of the second hydraulic cylinder 112, the third hydraulic cylinder 113, and the fourth hydraulic cylinder 114, and the tip of the connecting arm 105 is connected to each shifter shaft 90. Are connected to one end of each.

  In the first hydraulic cylinder 111, a first piston 98 including a large diameter portion 98a and a small diameter portion 98b is fixed to the other end of the rod 115, and the large diameter portion 98b includes the large piston portion 98b. A cylindrical second piston 99 having an outer diameter larger than the diameter portion 98a is fitted on the small diameter portion 98b so as to be slidable in the axial direction. The second piston 99 is constantly urged toward the large diameter portion 98a by a spring or the like so as not to be detached from the small diameter portion 98b in the axial direction. Oil chambers 109 and 110 are formed in the longitudinal direction of the body across the piston 100 composed of the first piston 98 and the second piston 99. The oil chambers 109 and 110 are connected to the electromagnetic switching valve 121 and the oil passage 125a. -It is connected via 125b.

  In the neutral state, pressure oil is supplied from the electromagnetic switching valve 121 to both the oil chambers 109 and 110 via the oil passages 125a and 125b, respectively, but the pressure receiving area on the oil chamber 110 side of the piston 100 is larger. Since it is larger than the pressure receiving area on the oil chamber 109 side, the piston 100 is pushed to the oil chamber 109 side and held at a position where the inner peripheral corner of the second piston 99 contacts the shoulder portion 95a of the shifter case 95. Is done. This holding position is defined as a neutral position. Thereby, the piston 100 can be accurately positioned at the neutral position.

  In the case of the first speed, by stopping only the supply of pressure oil to the oil chamber 109 by the electromagnetic switching valve 121, the piston 100 is pushed toward the oil chamber 109 by the oil pressure in the oil chamber 110, and the shoulder Only the first piston 98 is slid and held to the first speed position corresponding to the outermost end of the oil chamber 109 with the second piston 99 left blocked by the portion 95a being immovable. In the case of the third speed, by stopping only the supply of pressure oil to the oil chamber 110 by the electromagnetic switching valve 121, the piston 100 is pushed toward the oil chamber 110 by the oil pressure in the oil chamber 109, and the oil The third speed position corresponding to the outermost end of the chamber 110 is held.

  The remaining hydraulic cylinders 112, 113, and 114 are also provided with electromagnetic switching valves 122, 123, and 124, respectively. The electromagnetic switching valves 122, 123, and 124 include oil passages 126 a and 126 b, oil passages 127 a and 127 b, oil Via the passages 128a and 128b, the hydraulic chambers 112, 113, and 114 communicate with the oil chambers 109 and 110, respectively. Positioning of the speed position, neutral position, and 4th speed position, positioning of the 5th speed position, neutral position and 7th speed position by the third hydraulic cylinder 113, positioning of the 6th speed position, neutral position and 8th speed position by the fourth hydraulic cylinder 114 It can be carried out.

  In the configuration as described above, when the engine is started, all the electromagnetic switching valves 121 to 124 are in the non-excited positions as shown in FIG. 3, and the main transmission 8 is held neutral when stopped. When a shift command signal is sent to a predetermined electromagnetic switching valve among the electromagnetic switching valves 121 to 124, the piston 100 moves to a predetermined shift position as described above, and the rod 115 fixed to the piston 100 moves. The forks 101, 102, 103, and 104 are moved through the connecting arm 105 while being guided by the shifter shaft 90, and the shifters 91a, 92a, 93a, and 94a are moved to the drive gears 61, 62, 63, and 64 of the respective speed stages. -Engage with either 65, 66, 67, or 68. Then, the forward power and the reverse power transmitted to the travel transmission shafts 16 and 17 are transmitted from the spline hub to any one of the main transmission drive trains via a shifter, where the main transmission output is performed after the main transmission is performed there. It is transmitted to the shaft 18, further sub-shifted by the sub-transmission device 9 and then transmitted to each axle, and the work vehicle 1 travels at various speed stages.

  A pump 106 is fixed to the mission case 23 so that the pump 106 can be driven by the input shaft 3 from the engine 2. The oil sucked by the pump 106 from the tank 107 through the oil filter 108 flows into the pump port 117 through the line filter 116 and branches to one of the transmission oil passage 118 for shift control and the other to the clutch. It flows into the clutch oil passage 119 for control. The pressure oil in the clutch oil passage 119 is in a state where the maximum pressure is regulated for circuit protection by the high pressure relief valve 120, the line filter 129, the electromagnetic proportional pressure reducing valve 130, the line filter 131, and the hydraulic oil passage 137. To the first clutch hydraulic cylinder 59 and also to the second clutch hydraulic cylinder 60 via a line filter 132, an electromagnetic proportional pressure reducing valve 133, a line filter 134, and a hydraulic oil passage 139. The

  Thus, the pistons 141 and 142 of the first clutch hydraulic cylinder 59 and the second clutch hydraulic cylinder 60 can be gradually and continuously moved using the electromagnetic proportional pressure reducing valves 130 and 133. For example, When the one clutch 55 and the second clutch 56 are multi-plate friction clutches, the clamping force between the friction plates is continuously changed by the pistons 141 and 142, and the transmission torque from the clutch disengaged state to the engaged state is continuously maintained. Can be changed.

  In addition, a relief valve 144 is provided in the oil passage 143 on the downstream side of the relief valve 120, and the first pressure included in the main transmission 8 is in a state where the maximum pressure as lubricating oil is regulated by the relief valve 144. Lubricating oil is supplied to the first clutch 55 and the second clutch 56 via lubricating oil passages 138 and 140, respectively.

  Further, the main shift control of the shifter and clutch operating mechanism as described above will be described by taking as an example the case where the current speed stage is the forward high speed 1st speed and the next speed stage is the forward high speed 2nd speed. Among these, the forward high speed 1st is a speed stage consisting of the forward speed in the forward / reverse switching device 7, the high speed in the auxiliary transmission 9, and the first speed in the main transmission 8. The forward / reverse switching device 7 and the auxiliary transmission device 9 are left as they are, and only the main transmission device 8 is a speed stage shifted from the first speed stage to the second speed stage. Here, simply, the forward high speed 1st is the forward 1st speed, and the forward high speed 2nd is the forward 2nd speed.

  While traveling at the first forward speed, the first clutch 55 is in an engaged state. At this time, since the shifter shaft 90 of the first fork 101 is held at the first speed position, the shifter 91 a is engaged with the first speed drive gear 61 via the first fork 101, and the main transmission output shaft 18. Is connected to the first travel transmission shaft 16 provided with the first clutch 55 via the first-speed gear train 61, 81. As a result, the forward power from the forward / reverse switching device 7 is transmitted in the order of the clutch input shaft 15, the first clutch 55, and the first traveling speed change shaft 16, and then the first forward gear train 61/81 changes the forward power to the first speed. The speed is changed, and the first forward power is transmitted from the main transmission output shaft 18 to the auxiliary transmission 9 as main transmission power. On the other hand, the second clutch 56 is disconnected and is in a disconnected state. At this time, the shifter shaft 90 of the second fork 102 is held at the neutral position, and the shifter 92 a is also held at the neutral position via the second fork 102.

  When an accelerator pedal 20 to be described later is depressed and a shift command signal from the first forward speed to the second forward speed is issued from a control device (not shown), the first clutch 55 is engaged, The engaged state of the connected first traveling speed change shaft 16 and the first speed gear trains 61 and 81 and the disengaged state of the second clutch 56 are not changed, and the first clutch connected to the second clutch 56 is not changed. The two-travel transmission shaft 17 is engaged with the second-speed gear train 62/81. That is, when the electromagnetic switching valve 122 is switched and the piston 100 of the second hydraulic cylinder 112 is moved and the shifter shaft 90 is moved to the second speed position, the shifter 92a is moved to the neutral position via the second fork 102. To the second speed drive gear 62 and, as a result, the main transmission output shaft 18 is connected to the second traveling speed change shaft 17 provided with the second clutch 56 via the second speed gear train 62 and 81. Connected. However, since the second clutch 56 is still in a disconnected state and the forward power from the forward / reverse switching device 7 to the second travel transmission shaft 17 remains disconnected, the second travel transmission shaft 17 and the second speed An excessive load on the transmission system due to the engagement with the gear trains 62 and 81 does not occur.

  When a little time has elapsed after the transmission command signal is issued, the control device issues a clutch connection / disconnection command signal indicating that the first clutch 55 gradually disengages and the second clutch 56 gradually disengages. Then, the electromagnetic proportional pressure reducing valves 130 and 133 are subjected to proportional pressure reduction control, and the piston 141 of the first clutch hydraulic cylinder 59 and the piston 142 of the second clutch hydraulic cylinder 60 gradually and continuously move, and the first clutch 55 The separation operation proceeds from the current on state to the off state, and the second clutch 56 is joined from the current off state to the on state, and the separation operation and the joining operation are performed in parallel.

  Further, when the clutch connection / disconnection command signal is continuously issued and reaches a predetermined time point, the first clutch 55 is completely turned off and the second clutch 56 is completely turned on. That is, while the clutch connection / disconnection command signal is issued, the first speed gear train 61/81 is always engaged with the first travel speed change shaft 16, and the second speed gear train 62/81 is always engaged with the second travel speed change shaft 17. Therefore, the forward power from the first traveling speed change shaft 16 connected to the first clutch 55 to the first gear trains 61 and 81 gradually decreases, while the second power connected to the second clutch 56 The forward power from the second traveling speed change shaft 17 to the second speed gear trains 62 and 81 gradually increases. As a result, the power from the first gear train 61/81 and the second gear train 62/81 to the main transmission output shaft 18 gradually switches from the first forward speed to the second forward speed, and finally to the second forward speed. During this time, the forward power from the forward / reverse switching device 7 is not interrupted.

  Further, when a certain amount of time has passed, a shift completion signal is issued from the control device, and the second clutch 56 is engaged, the second travel transmission shaft 17 connected to the second clutch 56 and the second gear trains 62 and 81. The engagement state of the first clutch 55 and the disengagement state of the first clutch 55 are not changed, and the first traveling speed change shaft 16 connected to the first clutch 55 and the first speed gear train 61/81 are not engaged. Put it in a state. That is, the switching valve 121 is controlled to move the piston 100 of the first hydraulic cylinder 111, the shifter shaft 90 is moved to the neutral position, and the shifter 91 a is moved through the first fork 101 to the first speed drive gear 61. To the neutral position. As a result, the first clutch 55 is disengaged and the second clutch 56 is engaged, and the first travel transmission shaft 16 connected to the first clutch 55 is disengaged from the first-speed gear trains 61 and 81. The shift from the first forward speed to the second forward speed is completed. However, since the first clutch 55 is in the disengaged state and the forward power from the forward / reverse switching device 7 to the first travel transmission shaft 16 remains disconnected, the first travel transmission shaft 16 and the first speed gear train 61. No excessive load on the transmission system due to the non-engagement with 81 occurs.

  Shift control between other speed stages is performed in the same process as described above. That is, the gear-type transmission 33 which is a stepped transmission includes a first clutch 55 for connecting / disconnecting power to the first, third, fifth and seventh gear trains which are odd-numbered gear trains. And a second clutch 56 for connecting / disconnecting power to the second, fourth, sixth and eighth gear trains, which are even-numbered shift drive trains. In the selected state, the main transmission 8 for temporally overlapping one of the first clutch 55 and the second clutch 56 and the other joining operation is provided. Traveling gear shifting can be performed continuously without interrupting power transmission to the axle 32, and driving operability and driving stability can be further improved compared to the case of using a normal stepped transmission. .

Next, the shift control configuration by the torque converter 4 and the gear type transmission 33 as described above will be described with reference to FIGS. 1, 4, and 10.
In the torque converter 4, the lockup mechanism 80 includes a lockup clutch 39 and an electromagnetic valve 150 that supplies pressure oil for operation control to the lockup clutch 39 via an oil passage 149. Are connected to a controller 151 that performs shift control and the like. The controller 151 is connected with a lockup switch 145 for setting the lockup clutch 39 to be turned on and off. By operating a lockup lever 145a of the lockup switch 145, the controller 151 The hydraulic oil is supplied to and discharged from the lockup clutch 39 via the path 149. As a result, the lockup clutch 39 is brought into close contact with the front cover 34 and the lockup clutch 39 is connected to the front cover 34 when the input shaft 3 is directly connected to the output shaft 5 without passing through the torque converter 4. The lockup cut-off state (position 147) in which the input shaft 3 is connected to the output shaft 5 via the torque converter 4 and the manual selection mode for arbitrarily selecting either the lockup on state or the lockup off state On the other hand, one of the automatic selection modes (position 148) for automatically switching between the two states can be selected.

  The controller 151 is connected to the solenoid valves 121, 122, 123, 124, 130, and 133 of the main transmission 8 and the accelerator pedal 20, and the accelerator pedal 20 is depressed. The speed is automatically changed from the first speed to the eighth speed depending on the relationship between the amount and the vehicle speed at that time. Of course, a main speed change lever that can select one of the first speed to the eighth speed may be provided so that the main speed change lever can be manually shifted.

  In the forward / reverse switching device 7, the shifter 54 a is connected to the controller 151 via the hydraulic cylinder 152 and the electromagnetic valve 153, and operates the forward / reverse lever 154 a of the forward / reverse switching switch 154 connected to the controller 151. Thus, the shifter 54a engages with the clutch tooth portion 49a and transmits the forward power from the forward driven gear 49 to the clutch input shaft 15, and the shifter 54a does not engage with any of the clutch tooth portions. A neutral stage (position 156) that does not transmit power to the clutch input shaft 15 and a reverse stage (position 157) in which the shifter 54a engages the clutch tooth portion 50a and transmits reverse power from the reverse driven gear 50 to the clutch input shaft 15. One of them can be selected.

  In the auxiliary transmission 9, the shifter 88a is connected to the controller 151 via the hydraulic cylinder 158 and the electromagnetic valve 159, and the shifter 89a is also connected to the controller 151 via the hydraulic cylinder 164 and the electromagnetic valve 165. By operating the auxiliary transmission lever 160a of the auxiliary transmission switch 160 connected to 151, the shifter 88a is engaged with the clutch tooth portion 74a and the main transmission power is transmitted from the main transmission output shaft 18 to the auxiliary transmission output shaft 19 as it is. And a low speed at which the shifter 88a engages the clutch tooth portion 75a and decelerates and transmits the main transmission power from the main transmission output shaft 18 to the auxiliary transmission output shaft 19 via the low-speed gear train. And the shifter 89a engages with the clutch tooth portion 76a, and the main transmission output shaft 18 passes through the creep gear train. The auxiliary speed change output shaft 19 is to select one of the super-slow creep stage and transmits the decelerated main transmission power increase (position 163).

  In such a configuration, first, after the work vehicle 1 is stopped, the forward / reverse switching device 7 is set to the forward gear or the reverse gear, and the auxiliary transmission 9 is set to any one of the high speed gear, the low speed gear, and the creep gear. Then, the brake pedal release operation and the accelerator pedal 20 depressing operation are sequentially performed to start the work vehicle. As the vehicle speed increases, the solenoid valves 121, 122, 123, 124, 130, and 133 are operated based on a vehicle speed signal from a vehicle speed sensor (not shown) attached to the auxiliary transmission output shaft 19 and the like. The transmission 8 is automatically shifted to a speed stage having a speed ratio suitable for the vehicle speed among 1st to 8th speeds.

  When the lockup switch 145 is operated to set the lockup on state during such traveling, the lockup clutch 39 is brought into close contact with the front cover 34 as described above, and the input shaft 3 does not go through the torque converter 4. Directly connected to the output shaft 5, the engine power from the engine 2 can be transmitted as it is to the gear-type transmission 33 such as the main transmission 8 or the subtransmission 9 on the downstream side, and the speed fluctuates due to torque fluctuations. Low-speed traveling suitable for work can be performed without using the torque converter 4 that tends to increase power transmission loss (hereinafter referred to as “work travel mode”). Conversely, when the lock-up switch 145 is operated to set the lock-up off state, the lock-up clutch 39 is separated from the front cover 34, and the input shaft 3 is connected to the output shaft 5 via the torque converter 4. The engine power from 2 can be automatically changed to a torque suitable for high speed running and transmitted to the gear type transmission 33 (hereinafter referred to as “high speed running mode”).

  Further, when the automatic selection mode is set, the control configuration is such that the automatic selection mode is automatically assigned to either the high-speed driving mode or the work driving mode. For example, when the driver selects the high speed stage with the auxiliary transmission 9, the high speed traveling mode is set, and when the driver selects the low speed stage or the creep speed, the working traveling mode can be set. As a result, the driver only needs to depress the accelerator pedal 20 during traveling after setting the forward / reverse speed and the sub speed stage before starting, and is particularly conscious of the on / off state of the lock-up clutch 39. Work can be done without Of course, in this automatic selection mode, not the speed stage of the sub-transmission device 9 (hereinafter referred to as “sub-speed stage”), but the speed stage of the forward / reverse switching device 7 and the main transmission device 8 It may be automatically assigned to either of the work travel modes.

  That is, in the work vehicle transmission mechanism including the gear type transmission 33 which is a stepped transmission that changes the engine power output from the engine 2 and transmits it to the axle, the engine 2, the gear type transmission 33, A torque converter 4 is interposed between the high-speed traveling mode in which the engine power is transmitted to the gear-type transmission 33 via the torque converter 4 and the gear-type transmission 33 is directly supplied with the engine power. A work travel mode for transmitting and shifting gears, and in each of the work travel mode and the high speed travel mode, each speed stage of the gear-type transmission 33, for example, the high speed stage of the auxiliary transmission 9 Since the gear shift control configuration can set the low speed stage and the creep stage, when the speed stage of the gear-type transmission 33 is set to the high speed running mode, the speed stage is set once. , Can be automatically changed to the torque suitable torque to high speed by the torque converter 4, sufficient driving operability and running stability can be obtained by performing the accelerated and shifted to the extremely smooth. On the other hand, when the speed stage of the gear-type transmission 33 is set to the working travel mode, the gear is shifted only by the gear-type transmission 33, so that the torque greatly fluctuates by traveling on a soft field having a large travel resistance. However, it is possible to work at a constant speed, and furthermore, the power transmission loss can be suppressed smaller than when using the torque converter 4 with fluid, and high work efficiency is ensured by stabilizing the work speed and improving the power transmission efficiency. can do.

  Further, as described above, the torque converter 4 is provided with the lock-up mechanism 80 that directly transmits the engine power to the gear-type transmission 33 that is the stepped transmission, so that the lock-up clutch of the lock-up mechanism 80 is provided. With the clutch engagement operation of 39, the engine power can be directly transmitted to the gear-type transmission 33 without providing a special detour transmission path, the number of parts is reduced, the parts cost is reduced, and the speed change mechanism is compact. And improvement in maintainability can be achieved.

  In addition, the gear-type transmission 33 that is the stepped transmission includes a sub-transmission that changes the main transmission power from the main transmission 8 to a plurality of sub-speed stages, that is, a high speed stage, a low speed stage, and a creep stage. Since the device 9 is provided and a lock-up switch 145 is provided as a switching means for automatically assigning to a predetermined traveling mode of the high-speed traveling mode and the working traveling mode when each sub-speed stage is selected, the sub-speed stage is selected. The traveling mode can be set to any one of them, and when the work vehicle 1 such as a tractor has a large speed stage, the operation of selecting the traveling mode that tends to be complicated can be simplified and the shift operability can be improved. it can.

  In addition, as shown in FIG. 10, either when the lock-up on state is selected in the manual selection mode, or when the low speed stage or the creep stage is selected in the automatic selection mode and the work travel mode is automatically set, As described above, the lock-up clutch 39 is engaged, and the engine power is directly transmitted to the gear-type transmission without going through the torque converter 4. In such a case, which of the main transmission 8 Even in the speed stage, when the work vehicle 1 is started, a first-speed gear train that is a low-speed gear train is automatically selected, and the control is configured to start by the first-speed gear train. Thereby, it is possible to generate a large starting torque necessary for starting the work vehicle 1 at the start, regardless of the speed stage before the start.

  That is, the gear-type transmission 33 which is the stepped transmission, the main transmission 8 in this embodiment, includes a first-speed gear train which is a low-speed gear train for starting used when starting the work vehicle 1. 61 and 81 are provided, and the first speed gear train 61 and 81 is selected at the time of starting. Therefore, even when the vehicle is driven by the engine power output without passing through the torque converter 4, the first speed gear for starting is used. By using the row, the work vehicle 1 can be reliably started without causing an engine stall, and a stable starting performance can be always obtained. Furthermore, since the vehicle starts using the low-speed gear train, the load at the time of starting is reduced, and sufficient durability can be obtained even with a small clutch pack. This low speed gear may be a second gear train or a third gear train when the number of stages of the main transmission 8 is large.

  Further, as described above, the input shaft 3 connected to the crankshaft 40 of the engine 2 can be directly connected to the PTO shaft 14 from the PTO transmission 6 without going through the torque converter 4. For this reason, the engine power is transmitted to the PTO shaft 14 without passing through the torque converter 4 in any travel mode, and the PTO shaft 14 is always rotated at a constant speed. It enables stable driving of connected work machines.

  That is, the work vehicle transmission mechanism includes a PTO transmission 6 that shifts engine power and transmits the engine power to the PTO shaft 14. The engine power is directly transmitted to the PTO transmission 6 without passing through the torque converter 4. Therefore, the engine power can always be directly transmitted to the PTO shaft 14 and driven at a constant speed in any travel mode, and the engine power can be directly transmitted to the PTO shaft 14 even in the work travel mode. There is no need to provide a separate detour transmission path, and the lock-up mechanism 80 can be reduced in size by the amount that the transmission power to and from the PTO shaft is no longer required. Can be made more compact and maintainability can be improved.

The overall configuration of the work vehicle 201 according to the second embodiment of the present invention will be described with reference to FIG.
In the work vehicle 201, unlike the first embodiment, the input shaft 203 connected to the crankshaft 40 of the engine 2 is connected to the PTO shaft 14 from the PTO transmission 6 via the torque converter 204. Yes. In the following description, components equivalent to those in the first embodiment are denoted by the same reference numerals.

  The work vehicle 201 includes an engine 2 and a gear-type transmission 233 that changes engine power, and the crankshaft 40 of the engine 2 is connected to an input shaft 203, and the input shaft 203 has a lock-up mechanism. The engine power is connected to the output shaft 205 via the torque converter 204 so that the engine power is output to the gear transmission 233 via the input shaft 203, the torque converter 204 and the output shaft 205.

  Here, in the torque converter 204, the input shaft 203 is fixed to the front cover 234, the pump impeller 235 is connected to the front cover 234, the output shaft 205 is connected to the turbine runner 236, and further the transmission A stator 237 is supported on the front portion of the case 223 via a one-way clutch 38. A lockup clutch 239 is disposed between the front cover 234 and the turbine runner 236. Then, a connection state between the input shaft 203 and the output shaft 205 is changed by a lockup mechanism 280 described later including the lockup clutch 239 and the like.

  However, unlike the first embodiment, not the input shaft 203 but the output shaft 205 is extended in the mission case 223, and the extended end is the same as in the first embodiment, and the PTO clutch 10 and the PTO transmission device. 6 is connected to the PTO shaft 14 via the input shaft 203, the torque converter 204, the output shaft 205, the PTO clutch 10, and the PTO transmission 6 through the PTO transmission device 6. 14 is transmitted.

  The output shaft 205 is connected to the sub-transmission output shaft 219 via a gear-type transmission 233 including a forward / reverse switching device 207, a main transmission 208, and a sub-transmission device 209 that are connected in the mission case 223. After the rotation direction and speed of the engine are switched, the engine power is transmitted to the auxiliary transmission output shaft 219 as transmission power. In the same manner as in the first embodiment, the auxiliary transmission output shaft 219 causes the rotation input to the bull gear 25 from the auxiliary transmission output shaft 219 via the bevel gear 24 to be differentially rotated by the differential gear device 43 with the differential lock mechanism 44. Transmission is performed from the axles 32 and 32 to the rear wheels 21 and 21.

Next, the gear transmission 233 will be described with reference to FIGS.
In the transmission case 223, the clutch input shaft 215, the first traveling transmission shaft 216, the second traveling transmission shaft 217, and the main transmission output shaft 218 are parallel to the output shaft 205 and the auxiliary transmission output shaft 219. It is installed horizontally in the longitudinal direction of the aircraft.

  Of these, on the output shaft 205, a forward drive gear 249 and a reverse drive gear 250 are arranged in order from the rear so that they can rotate relative to each other. A spline hub is provided between the forward drive gear 249 and the reverse drive gear 250. 254 is engaged so as not to be relatively rotatable, and a shifter 254a is engaged with the spline hub 254 so as to be slidable in the axial direction but not relatively rotatable. Clutch tooth portions 249a and 250a are formed at portions of the drive gears 249 and 250 toward the spline hub 254, respectively.

  Further, a forward driven gear 247 and a reverse driven gear 248 having the same diameter are fixed on the clutch input shaft 215 in order from the rear, and the forward driven gear 247 is meshed with the forward drive gear 249. At the same time, the reverse driven gear 248 meshes with an idle gear 253 on an intermediate shaft 252 provided in the longitudinal direction of the machine body, and the idle gear 253 meshes with the reverse drive gear 250 to form a forward / reverse switching device 207. Has been.

  Thus, by engaging the clutch tooth portions 249a and 250a with the shifter 254a, the corresponding drive gear can be engaged with the output shaft 205 so as not to be relatively rotatable, and the output shaft 205 can be engaged with the clutch input shaft 215. It is possible to transmit forward power or reverse power.

  Further, a friction multi-plate type main transmission clutch 256 is disposed behind the forward driven gear 247 on the clutch input shaft 215, and the main transmission clutch 256 is arranged in order from the front, the first clutch portion 256a and the second clutch portion. The first clutch portion 256a and the second clutch portion 256b are provided adjacent to each other back to back and use a common clutch plate portion 256c and the like.

  That is, the first clutch portion 256a that is the first clutch and the second clutch portion 256b that is the second clutch are arranged back to back on the clutch input shaft 215 that is a common transmission shaft. Compared to the case where the two are separated and separated, the space for clutch arrangement can be narrowed, the clutch parts can be shared, the parts cost can be reduced, and the speed change mechanism can be made more compact. .

  A first clutch output gear 257 is rotatably provided on the clutch input shaft 215 in front of the first clutch portion 256a. When the first clutch portion 256a is inserted, the first clutch output gear 257 is provided. 257 is engaged with the clutch input shaft 215 via the first clutch portion 256a so as not to be relatively rotatable. A first clutch hydraulic cylinder 259 is provided for the clutch on / off. Similarly, a second clutch output gear 258 is rotatably provided behind the second clutch portion 256b on the clutch input shaft 215. When the second clutch portion 256b is inserted, the second clutch output gear 258 is rotated. The gear 258 is engaged with the clutch input shaft 215 through the second clutch portion 256b so as not to be relatively rotatable. A second clutch hydraulic cylinder 260 is provided to turn the clutch on and off. The first clutch hydraulic cylinder 259 and the second clutch hydraulic cylinder 260 gradually transmit the transmission torque from the disengaged state to the engaged state of the first clutch portion 256a and the second clutch portion 256b, as in the first embodiment. It can be changed continuously.

  Further, the first traveling speed change shaft 216 is disposed on the right side and the second traveling speed change shaft 217 is disposed on the left side with the clutch input shaft 215 interposed therebetween. A first input gear 251 and a second input gear 255 are fixed on the second travel transmission shaft 217, respectively. Of these, the first input gear 251 is always meshed with the first clutch output gear 257, and the second input gear 255 is meshed with the second clutch output gear 258. As a result, when the first clutch portion 256a and the second clutch portion 256b are turned on and off, the forward power from the output shaft 205 is applied to one of the travel transmission shafts 216 and 217 selected by the on / off operation. Or reverse power can be transmitted.

  That is, as described above, the forward / reverse switching device 207 that switches the traveling direction back and forth is disposed on the lower transmission side of the torque converter 204, and the first clutch is disposed on the lower transmission side of the forward / backward switching device 207. Since a certain first clutch portion 256a and a second clutch portion 256b, which is a second clutch, are arranged, the forward / reverse switching is performed on the output shaft 205 from the torque converter 204 in the same manner as in the first embodiment. Power transmission loss due to forward / reverse switching with torque fluctuation can be greatly reduced, power transmission efficiency can be improved, and the forward / reverse switching device 207 and the first clutch portion 256a and the second clutch portion 256b are installed close to each other, The space required for these installations can be reduced, and the speed change mechanism can be made compact.

  Since the first clutch portion 256a and the second clutch portion 256b are centrally arranged as a main transmission clutch 256, the first clutch portion 256a and the second clutch portion 256b include the relief valve 120 and A single oil passage 343 that is divided from the relief valve 144 and extends to the vicinity of the clutch portions 256a and 256b, and an oil passage 338 that branches into two from the oil passage 343 in the vicinity of the clutch portions 256a and 256b. The lubricating oil can be supplied via the 340, which makes it possible to shorten the oil passage required for supplying the lubricating oil compared to the first embodiment, and to reduce the cost by reducing the number of parts and the number of processed parts. And improve maintainability.

  The space in the transmission case 223 is partitioned by a front first chamber 271 across the bearing wall 269, a rear second chamber 272, and a rear third chamber 273 across the bearing wall 270. The forward / reverse switching device 207 and the main transmission clutch 256 are disposed in the first chamber 271, and the main transmission device 208 is disposed in the second chamber 72. The configuration of the main transmission 208 and the shifter and clutch operating mechanism and control thereof are the same as those of the main transmission 8 of the first embodiment, and thus detailed description thereof will be omitted. Also, after the forward power or the reverse power transmitted to the travel transmission shafts 216 and 217 is smoothly shifted to the first to eighth speeds in each main transmission drive train, the main transmission output shaft 218 is used as the main transmission power. To be able to communicate.

  Further, the leading end of the main transmission output shaft 218 passes through the bearing wall 270 and protrudes into the third chamber 273 and is connected to the auxiliary transmission 209. In the sub-transmission device 209, like the sub-transmission device 9 of the first embodiment, a bottom surface portion of a cylindrical high-speed shaft 74 having one end opened is fixed to the protruding portion of the transmission output shaft 218. A front end of the auxiliary transmission output shaft 219 is pivotally supported by the opening of the shaft 74 so as to be rotatable. On the auxiliary transmission output shaft 219, the low-speed gear 75 and the creep gear 76 are provided so as to be relatively rotatable in order from the front.

  However, unlike the first embodiment, a large-diameter gear 285 that meshes with a gear 77 that is circularly fixed to the front portion of the high-speed shaft 74, a medium-diameter gear 286 that meshes with the low-speed gear 75, and a reduction gear 79. Each of the small-diameter gears 287 that mesh with the creep gear 76 is fixed to the auxiliary transmission shaft 278 that is rotatably supported in the third chamber 273 in parallel with the auxiliary transmission output shaft 219.

  Accordingly, also in the second embodiment, the main transmission output shaft 218 is connected to the auxiliary transmission output shaft 219 from the high speed gear train including the high speed shaft 74, the gear 77, the large diameter gear 285, the medium diameter gear 286, and the low speed gear 75. A plurality of sub-transmission drive trains such as a low-speed gear train composed of a gear 77, a large-diameter gear 285, a small-diameter gear 287, a reduction gear 79, and a creep gear train 76 are formed.

  Further, since the sub-transmission configuration on the sub-transmission output shaft 19 is the same as that of the sub-transmission device 9 of the first embodiment, detailed description is omitted, but the sub-transmission device 209 of the second embodiment also uses the main transmission. The main transmission power transmitted to the output shaft 218 is transmitted to the auxiliary transmission output shaft 219 as auxiliary transmission power after being shifted to the high speed, low speed, and creep stages by each of the auxiliary transmission drive trains.

Next, a shift control configuration by the torque converter 204 and the gear type transmission 233 will be described with reference to FIGS.
In the torque converter 204, the lock-up mechanism 280 includes a lock-up clutch 239 and an electromagnetic valve 350 that supplies pressure oil for operation control to the lock-up clutch 239 via an oil passage 349. Are connected to a controller 351 for performing gear shift control and the like. The controller 351 is connected to the lockup switch 145 for setting the on / off state of the lockup clutch 239. By operating the lockup lever 145a of the lockup switch 145, the electromagnetic valve 350 is operated. The hydraulic oil is supplied to and discharged from the lockup clutch 239 via the oil passage 349. As a result, the lockup clutch 239 is brought into close contact with the front cover 234 and the input shaft 203 is directly connected to the output shaft 205 without passing through the torque converter 204 (position 146), and the lockup clutch 239 is moved to the front cover 234. The lockup cut-off state (position 147) in which the input shaft 203 is connected to the output shaft 205 via the torque converter 204 and the lockup off state and the lockup off state are arbitrarily selected. On the other hand, one of the automatic selection modes (position 148) for automatically switching between the two states can be selected.

  The controller 351 is connected to each solenoid valve 121, 122, 123, 124, 130, 133 of the main transmission 208 and an accelerator pedal 20, and the amount of depression of the accelerator pedal 20 is determined. The speed is automatically changed from the first speed to the eighth speed in relation to the vehicle speed at that time.

  In the forward / reverse switching device 207, a shifter 254a is connected to a controller 351 via a hydraulic cylinder 352 and an electromagnetic valve 353, and operates a forward / reverse lever 154a of a forward / reverse switching switch 154 connected to the controller 351. Accordingly, the shifter 254a engages with the clutch tooth portion 249a and transmits the forward power from the forward drive gear 249 to the clutch input shaft 215, and the shifter 254a does not engage with any clutch tooth portion. A neutral stage (position 156) that does not transmit power to the clutch input shaft 215, and a reverse stage (position 157) in which the shifter 254a engages the clutch tooth portion 250a and transmits reverse power from the reverse drive gear 250 to the clutch input shaft 215. One of them can be selected.

  In the auxiliary transmission 209, the shifter 88a is connected to the controller 351 via a hydraulic cylinder 358 and an electromagnetic valve 359, and the shifter 89a is also connected to the controller 351 via a hydraulic cylinder 364 and an electromagnetic valve 365. By operating the auxiliary transmission lever 160a of the auxiliary transmission switch 160 connected to 351, the shifter 88a is engaged with the clutch tooth portion 74a and the main transmission power is transmitted from the main transmission output shaft 218 to the auxiliary transmission output shaft 219 as it is. And a low speed at which the shifter 88a engages the clutch tooth portion 75a and decelerates and transmits the main transmission power from the main transmission output shaft 218 to the auxiliary transmission output shaft 219 via the low-speed gear train. And the shifter 89a engages with the clutch tooth portion 76a and the main transmission output shaft 218 The auxiliary speed change output shaft 219 through a gear train has to select one of the super-slow creep stage and transmits the decelerated main transmission power increase (position 163).

  In such a configuration, as in the first embodiment, with the work vehicle 201 stopped, first, the forward / reverse switching device 207 is set to the forward gear or the reverse gear, and the auxiliary transmission 209 is set to the high speed / low speed / creep speed. Then, the brake pedal release operation and the accelerator pedal 20 depression operation are sequentially performed to start the work vehicle. As the vehicle speed increases, the solenoid valves 121, 122, 123, 124, 130, and 133 are operated based on a vehicle speed signal from a vehicle speed sensor (not shown) attached to the auxiliary transmission output shaft 219 and the like. The transmission device 208 is automatically shifted to a speed stage having a speed ratio suitable for the vehicle speed among 1st to 8th speeds.

  When the lockup switch 145 is operated to set the lockup on state during such traveling, the lockup clutch 239 is in close contact with the front cover 234, and the input shaft 203 is connected to the output shaft 205 without passing through the torque converter 204. Directly connected, the engine power from the engine 2 can be transmitted as it is to the gear-type transmission 233 such as the main transmission 208 and the sub-transmission 209 on the downstream side, and the above-described work travel that enables low-speed travel suitable for work When the mode is set and, conversely, when the lock-up off state is set, the lock-up clutch 239 is separated from the front cover 234, and the input shaft 203 is connected to the output shaft 205 via the torque converter 204. The high-speed driving mode can automatically change the engine power to a torque suitable for high-speed driving. It is set to.

  In addition, when the automatic selection mode is set, the control configuration automatically distributes to either the high speed driving mode or the work driving mode. It is only necessary to depress the accelerator pedal 20, and the operation can be performed without being particularly aware of the on / off state of the lock-up clutch 239. As a result, the driver can freely select a driving mode suitable for the driving state. Similarly to the case of the first embodiment, when the speed stage of the gear type transmission 233 is set to the high speed driving mode, Once the speed stage is set, the torque converter 204 can automatically change the torque to a torque suitable for high-speed driving, eliminating the need for complicated gear shifting operations such as pedals and levers when driving on the road. In addition, acceleration and shifting can be performed very smoothly, and sufficient running stability can be obtained. On the other hand, when the speed stage of the gear-type transmission 233 is set to the working travel mode, the gear is shifted only by the gear-type transmission 233, so that the torque greatly fluctuates by traveling on a soft field having a large travel resistance. However, it is possible to work at a constant speed, and furthermore, power transmission loss can be suppressed smaller than when using the torque converter 204 by fluid, and high work efficiency is ensured by stabilizing the work speed and improving power transmission efficiency. It can be done. Similarly to the first embodiment, the main transmission 208 is provided with first speed gear trains 61 and 81 which are low-speed gear trains for starting that are used when the work vehicle 201 is started. Even if the gear train is selected and the engine power is output without passing through the torque converter 204, the engine can be operated without causing an engine stall by using the first gear train for starting. The vehicle 201 can be started reliably, and a stable start performance can be always obtained. Furthermore, since the vehicle starts using the low-speed gear train, the load at the time of starting is reduced, and sufficient durability can be obtained even with a small clutch pack.

  Unlike the first embodiment, the output shaft 205 connected to the PTO shaft 14 via the PTO clutch 10 and the PTO transmission 6 is connected to the input shaft 203 from the engine 2 via the torque converter 204. ing. For this reason, the PTO shaft 14 is directly connected to the engine 2 and is always rotated at a constant speed in the work travel mode in the lock-up-on state, but in the high-speed travel mode in the lock-up off state, Since it is rotated at a rotational speed that changes accordingly, it is suitable for operations that require a small load but need to automatically shift according to the traveling speed, such as seeding and spraying operations at high speed. ing.

Next, another embodiment of the second embodiment will be described with reference to FIG.
The working vehicle 401 of this embodiment is different from the second embodiment only in the auxiliary transmission 409 of the gear type transmission 433, and other than that, the engine 2, the torque converter 204, the forward / reverse switching device 207, the main transmission clutch 256, the main transmission clutch 256, The transmission 208, the PTO transmission 6, the differential gear device 43, and the like have the same configuration as in the second embodiment. Specifically, the auxiliary transmission 409 of this embodiment is provided with a friction multi-plate type auxiliary transmission clutch 402 for connecting and disconnecting the main transmission power from the main transmission 208 on the transmission upper side of the auxiliary transmission gear train. ing.

  In the auxiliary transmission device 409, a bottom surface portion of a cylindrical shaft 403 having one end opened is fixed to the rear end of the main transmission output shaft 218, and the auxiliary transmission output shaft is provided in the opening portion of the shaft 403. A front end of 219 is pivotally supported, and a low-speed gear 404 and a high-speed gear 405 are provided on the auxiliary transmission output shaft 219 so as to be relatively rotatable in order from the front. A sub-transmission shaft 406 is rotatably supported in parallel with the sub-transmission output shaft 219, a gear 408 is fixed to the front portion of the sub-transmission shaft 406, and the gear 408 is fixed to the shaft 403. The main transmission power is transmitted to the auxiliary transmission shaft 406 via these gears 407 and 408.

  On the auxiliary transmission shaft 406, the auxiliary transmission clutch 402 is disposed behind the gear 408, and on the auxiliary transmission shaft 406 further rearward of the auxiliary transmission clutch 402, a cylindrical clutch shaft 410 is relatively disposed. When the auxiliary transmission clutch 402 is engaged, the clutch shaft 410 is engaged with the auxiliary transmission shaft 406 via the auxiliary transmission clutch 402 so as not to be relatively rotatable.

  Further, on the clutch shaft 410, a small-diameter gear 411 and a large-diameter gear 412 are installed in an order from the front, and the small-diameter gear 411 is meshed with the low-speed gear 404, and the large-diameter gear 412 is connected to the high-speed gear 412. A sub-transmission drive train that is meshed with the gear 405 and includes a low-speed gear train 411 and 404 and a high-speed gear train 412 and 405 is formed. A spline hub 407 is engaged with the auxiliary transmission output shaft 219 between the low speed gear 404 and the high speed gear 405 so as not to be relatively rotatable. A shifter 407a is slidable in the axial direction and relatively rotated with respect to the spline hub 407. Clutch tooth portions 404a and 405a are formed at portions of the low-speed gear 404 and the high-speed gear 405 that are incapable of being engaged and directed toward the spline hub 407.

  In such a configuration, the forward / reverse switching device 207 is set to the forward gear or the reverse gear, the auxiliary transmission 409 is set to the low gear or the high gear, the auxiliary gear clutch 402 is turned on, and the brake pedal is released. When the work vehicle is started by sequentially performing the operation and the depression operation of the accelerator pedal 20, it is possible to travel in the work travel mode and the high speed travel mode in the same manner as in the first and second embodiments.

  Further, in this embodiment, when changing the sub-speed, the sub-transmission clutch 402 is temporarily disengaged during traveling, set to a predetermined sub-speed stage, and then clamped between the friction plates of the sub-transmission clutch 402. The force can be continuously changed by an actuator (not shown), and the transmission torque from the off state to the on state is also continuously changed. As a result, even when sub-shifting is performed during traveling, an excessive load on the transmission system due to engagement between the low-speed gear trains 411 and 404 or the high-speed gear trains 412 and 405 and the sub-transmission output shaft 219 is caused. It can be prevented from occurring.

  That is, the gear-type transmission 433 that is the stepped transmission is provided with a sub-transmission 409 that shifts the main transmission power from the main transmission 208 to a plurality of sub-speed stages. A friction multi-plate type sub-transmission clutch 402, which is a clutch capable of continuously changing the transmission torque, is provided between the main transmission 208 and a shift control configuration capable of gradually changing the on / off state of the sub-transmission clutch 402. Therefore, even when the vehicle is running, it is possible to make a smooth sub-shift, and it is not necessary to stop the work vehicle every time the sub-shift is shifted, thereby improving work efficiency and reducing driving load. be able to.

The present invention can be applied to all work vehicle transmission mechanisms including a stepped transmission that shifts engine power output from an engine and transmits the engine power to an axle.

It is a skeleton figure which shows the whole structure of the working vehicle concerning Example 1 of this invention. FIG. 3 is a partial cross-sectional view of the main transmission of the first embodiment. FIG. 3 is a hydraulic circuit diagram for shifting operation and clutch operation according to the first embodiment. It is also a block diagram. FIG. 5A is a side sectional view of the engaging portion, and FIG. 5B is a plan sectional view of the engaging portion. It is a skeleton figure which shows the whole structure of the working vehicle concerning Example 2 of this invention. FIG. 6 is a partial cross-sectional view of a main transmission of a second embodiment. FIG. 6 is a hydraulic circuit diagram for a speed change operation and a clutch operation according to the second embodiment. It is also a block diagram. It is explanatory drawing which shows the gear train used at the time of start. It is a skeleton figure which shows the whole structure of the working vehicle of another form of Example 2. FIG.

Explanation of symbols

1 Work vehicle 2 Engine 4/204 Torque converter 6 PTO transmission 7/207 Forward / reverse switching device 8/208 Main transmission 9/209 Sub transmission 14 PTO shaft 33/233 Stepped transmission 55 / 256a First clutch 56 / 256b Second clutch 61/81 Low speed gear train 80/280 Lock-up mechanism 145 Switching means 215 Common transmission shaft

Claims (8)

  In a work vehicle transmission mechanism having a stepped transmission that shifts engine power output from an engine and transmits the engine power to an axle, a torque converter is interposed between the engine and the stepped transmission, A high-speed travel mode in which engine power is transmitted to the stepped transmission via a torque converter for shifting, and a work travel mode in which engine power is directly transmitted to the stepped transmission for shifting. A speed change mechanism for a work vehicle, characterized in that a speed change control configuration is provided in which each speed stage of the stepped transmission can be set to one of the work travel mode and the high speed travel mode.   2. The work vehicle transmission mechanism according to claim 1, wherein the torque converter is provided with a lockup mechanism that directly transmits engine power to the stepped transmission.   3. The stepped transmission device is provided with a starting low speed gear train used when starting the work vehicle, and the low speed gear train is selected at the time of starting. The transmission mechanism for a work vehicle as described.   The stepped transmission includes a first clutch for connecting / disconnecting power to an odd-numbered shift drive train and a second clutch for connecting / disconnecting power to an even-numbered shift drive train, A main transmission is provided that temporally overlaps one of the first clutch and the second clutch in time with the shift drive train of each even-numbered stage selected. The work vehicle transmission mechanism according to any one of claims 1 to 3.   The stepped transmission is provided with a sub-transmission that shifts the main transmission power from the main transmission to a plurality of sub-speed stages, and when each sub-speed stage is selected, the high-speed travel mode and the work travel mode are selected. 5. The transmission mechanism for a work vehicle according to claim 4, further comprising switching means for automatically assigning the predetermined traveling mode.   A forward / reverse switching device that switches the traveling direction back and forth is disposed on the lower transmission side of the torque converter, and the first clutch and the second clutch are disposed on the lower transmission side of the forward / backward switching device. The work vehicle transmission mechanism according to claim 4 or 5.   7. The work vehicle transmission mechanism according to claim 4, wherein the first clutch and the second clutch are arranged back to back on a common transmission shaft. The work vehicle transmission mechanism includes a PTO transmission that shifts engine power and transmits the engine power to a PTO shaft, and the engine power is directly transmitted to the PTO transmission without passing through the torque converter. The transmission mechanism for a work vehicle according to any one of claims 1 to 7.

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