JP2009063049A - Transmission for work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a transmission capable of shifting an auxiliary transmission mechanism even during the traveling of a work vehicle. <P>SOLUTION: This transmission 4 for the work vehicle 1 includes: a hydrostatic continuously variable transmission mechanism 10; the auxiliary transmission mechanism 37; an auxiliary gear shift actuator 113; an auxiliary gear shift operation means 104; a forward travel/reverse travel shift mechanism 30; a forward travel/reverse travel shift actuator 112; a traveling speed detection means 102; and a control means 100. When the auxiliary gear shift operation means 100 is operated, traveling speed is detected, the forward travel/reverse travel shift mechanism 30 is changed over from a forward travel state or a reverse travel state to a neutral state, and the hydrostatic continuously variable transmission mechanism 10 is shifted so that the traveling speed at a shift stage after the shift of the auxiliary transmission mechanism 37 matches the detected traveling speed. After that, the auxiliary transmission mechanism 37 is shifted, and the forward travel/reverse travel shift mechanism 30 is changed over from the neutral state to the forward travel state or the reverse travel state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmission for a work vehicle including a hydrostatic continuously variable transmission mechanism in which one of a hydraulic pump and a hydraulic motor is a fixed displacement type and the other is a variable displacement type.

2. Description of the Related Art Conventionally, in a transmission device for a work vehicle such as a tractor having a gear selection type sub-transmission mechanism instead of a synchronous meshing type, the sub-transmission mechanism is required unless the vehicle is stopped due to the arrangement relationship between the sub-transmission mechanism and the main clutch. Could not be shifted from the high speed side to the low speed side or from the low speed side to the high speed side. On the other hand, in a transmission equipped with a hydraulic sub-transmission mechanism, the sub-transmission mechanism can be constituted by a hydrostatic continuously variable transmission so that the sub-transmission mechanism can be shifted even when the vehicle is running. In addition, it is possible to suppress a shift shock that occurs at the time of this shift switching (see, for example, Patent Document 1).
JP 2007-92951 A

  However, the transmission as in Patent Document 1 has a problem that the cost is increased because the sub-transmission mechanism is configured with the hydraulic pump and the hydraulic motor provided in the hydrostatic continuously variable transmission as variable displacement types. . In addition, when either one of the hydraulic pump or hydraulic motor of the hydraulic continuously variable transmission is not a variable displacement type but a fixed displacement type that can reduce costs, it is necessary to suppress a shift shock at the time of shift switching. there were.

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

  That is, in claim 1, a hydrostatic continuously variable transmission mechanism having a hydraulic pump and a hydraulic motor, a transmission actuator that shifts the hydrostatic continuously variable transmission mechanism, and a sub-transmission mechanism that includes a plurality of shift stages. A sub-transmission actuator for shifting the sub-transmission mechanism, sub-transmission operating means for switching the shift speed of the sub-transmission mechanism, a forward / reverse switching mechanism for switching the forward / reverse state, and a forward / backward switching for switching the forward / reverse switching mechanism. A transmission device for a work vehicle comprising a switching actuator, a travel speed detecting means for detecting a travel speed, and a control means for controlling the travel speed. When the sub-shift operation means is operated, the travel speed is detected. And the forward / reverse switching mechanism is switched from a forward state or a reverse state to a neutral state, and the hydrostatic continuously variable transmission mechanism is changed to a shift stage after the shift of the auxiliary transmission mechanism. After shifting so that the traveling speed matches the detected traveling speed, the auxiliary transmission mechanism is shifted, and the forward / reverse switching mechanism is switched from the neutral state to the forward state or the reverse state. .

  According to a second aspect of the present invention, when shifting the sub-transmission mechanism from the high speed side to the low speed side, if the detected traveling speed exceeds the shift region at the low speed stage of the sub-transmission mechanism, the hydrostatic pressure When the traveling speed of the type continuously variable transmission mechanism is shifted to the low speed side and the traveling speed reaches the maximum traveling speed at the low speed stage of the auxiliary transmission mechanism, the forward / reverse switching mechanism is switched from the forward movement state or the reverse movement state to the neutral state. The speed change mechanism is shifted to a low speed stage, and the forward / reverse switching mechanism is configured to switch from a neutral state to a forward state or a reverse state.

  According to a third aspect of the present invention, the shift of the auxiliary transmission mechanism is automatically performed when the auxiliary transmission operating means is operated for a predetermined time or longer.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, it is possible to shift the subtransmission mechanism from the low speed side to the high speed side without stopping the work vehicle even while traveling, and it is possible to suppress a shift shock that occurs during the shift switching. Since either one of the hydraulic pump and the hydraulic motor of the hydrostatic continuously variable transmission mechanism is a fixed capacity type, the cost can be reduced.

  According to the second aspect of the present invention, it is possible to shift the subtransmission mechanism from the high speed side to the low speed side without stopping the work vehicle, and it is possible to suppress a shift shock that occurs at the time of the shift switching. Since either one of the hydraulic pump and the hydraulic motor of the hydrostatic continuously variable transmission mechanism is a fixed capacity type, the cost can be reduced.

  According to the third aspect of the present invention, it is possible to prevent erroneous operation of the auxiliary transmission operation means.

  Next, embodiments of the invention will be described.

  FIG. 1 is a side view showing an overall configuration of a work vehicle including a transmission according to an embodiment of the present invention, FIG. 2 is a diagram showing a configuration of a power transmission mechanism of the transmission, and FIG. FIG. 4 is a block diagram showing the configuration, FIG. 4 is a flowchart showing a control mode when the subtransmission mechanism is shifted from the low speed side to the high speed side, and FIG. 5 is a diagram when the subtransmission mechanism is shifted from the low speed side to the high speed side. FIG. 6 is a flowchart showing a control method in the case of shifting the auxiliary transmission mechanism from the high speed side to the low speed side, and FIG. 7 is a flowchart showing the control method when shifting the auxiliary transmission mechanism from the high speed side to the low speed side. It is the figure which showed the structure of the swash plate control in the case of shifting to the low speed side.

  First, the construction of the work vehicle and its transmission will be described using the work vehicle according to an embodiment of the present invention as a tractor capable of mounting the work machine.

  As shown in FIGS. 1 and 2, in the work vehicle 1, a vehicle frame 2 is extended in the front-rear direction, and a front axle case is swingably provided at a front portion thereof. 3 is pivotally supported. On the other hand, a transmission 4 is provided at the rear portion of the vehicle frame 2, rear axle cases are disposed on the left and right sides of the transmission 4, and a rear wheel 5 is pivotally supported on the rear axle case.

  An engine 6 is supported in the middle of the vehicle frame 2 in the front and rear, and a flywheel 7 and a transmission mechanism 8 are sequentially connected to the engine 6. The transmission mechanism 8 is interlocked and connected by the transmission 4 and the transmission shaft 9, and the power from the engine 6 can be transmitted to the transmission 4 via the flywheel 7, the transmission mechanism 8, and the transmission shaft 9. Has been.

  The transmission 4 is provided with a travel system transmission path and a PTO drive path, and the power input from the engine 6 via the transmission shaft 9 and the like can be transmitted to the drive wheels through the travel system transmission path. At the same time, it can be output to a working machine or the like mounted on the work vehicle 1 through the PTO drive path.

  The traveling system transmission path includes a traveling system main transmission path and a traveling system sub-transmission path, and the power from the engine 6 acts on the rear wheels 5 acting as main drive wheels through the traveling system main transmission path. Transmission is possible, and transmission is possible to the front wheels 3 acting as auxiliary driving wheels through a traveling system auxiliary transmission path.

  Of the traveling system transmission paths, one traveling system main transmission path is formed by a hydrostatic continuously variable transmission mechanism 10 that adjusts traveling speed, a planetary gear mechanism 20, a main differential gear mechanism 40, and the like. The other travel system sub-transmission path is formed by the sub drive wheel switching mechanism 50, the travel system sub output shaft 60, and the like.

  The PTO drive path is formed by the PTO clutch mechanism 70, the PTO multi-stage transmission mechanism 80, and the like.

  In the travel system main transmission path, a hydrostatic continuously variable transmission mechanism (HST) 10 acts as a main transmission, and includes a hydraulic pump 11 and a hydraulic motor 12. In the hydrostatic continuously variable transmission mechanism 10, the hydraulic pump 11 is supported on the HST input shaft 13 so as not to be relatively rotatable, and the hydraulic motor 12 is supported on the HST output shaft 14 so as not to be relatively rotatable. The hydraulic pump 11 and the hydraulic motor 12 are fluidly connected.

  One of the hydraulic pump 11 and the hydraulic motor 12 is a fixed capacity type, and the other is a variable capacity type. In the present embodiment, the hydraulic motor 12 is a fixed displacement type, the hydraulic pump 11 is a variable displacement type, and the hydraulic pump 11 is provided with an output adjusting member. The hydraulic motor 12 may be a variable displacement type, and the hydraulic pump 11 may be a fixed displacement type.

  The output adjusting member includes a movable swash plate 15 and a control shaft for tilting the movable swash plate 15. Then, the control shaft is rotated around the axis by a shift actuator 111 such as a hydraulic cylinder that operates according to the operation of an operation means such as a main shift lever or a shift switch provided near the driver's seat, and based on the rotation The discharge amount of the hydraulic pump 11 is changed by tilting the movable swash plate 15.

  The HST input shaft 13 extends in the front-rear direction, and the engine 6 is linked to the front end of the HST input shaft 13 via a transmission shaft 9 and the like, and the power from the engine 6 can be output at the rear end. ing. Similarly, the HST output shaft 14 is also extended in the front-rear direction, so that transmission power from the hydraulic pump 11 and the hydraulic motor 12 based on the swash plate position of the movable swash plate 15 of the output adjusting member can be output from the rear end portion. Has been.

  A constant speed output shaft 16 is coaxially connected to the HST input shaft 13 so as to be relatively non-rotatable about the axis, while a speed change output shaft 17 is coaxially made non-rotatable about the axis on the same axis. It is connected. Then, constant speed power from the engine 6 is input to the planetary gear mechanism 20 via the constant speed output shaft 16, and speed change power from the hydrostatic continuously variable transmission mechanism 10 is received via the speed change output shaft 17. Input is allowed.

  The planetary gear mechanism 20 includes a sun gear 21, an internal gear 22, a planetary gear 23, and a composite output member 24. In this planetary gear mechanism 20, the sun gear 21 is supported by the speed change output shaft 17 so as not to rotate relative to the speed change output shaft 17, and the internal gear 22 is supported by the speed change output shaft 17 so as to be relatively rotatable and meshed with the constant speed gear 18. The constant speed gear 18 is supported on the constant speed output shaft 16 so as not to be relatively rotatable.

  The planetary gear 23 is meshed with the internal teeth of the sun gear 21 and the internal gear 22. The composite output member 24 is supported by the speed change output shaft 17 so as to be relatively rotatable, takes out a revolution component around the sun gear 21 of the planetary gear 23, and outputs a combined rotation of constant speed power and speed change power. Further, the composite output member 24 is interlocked with the composite input gear 25. The composite input gear 25 is supported on the traveling system transmission shaft 26 so as not to be relatively rotatable.

  The traveling system transmission shaft 26 extends in the front-rear direction, followed by a hydraulic multi-plate forward / reverse switching mechanism 30 at the rear thereof, and the combined output from the planetary gear mechanism 20 is transmitted to the forward / reverse switching mechanism 30. It has become so. The forward / reverse switching mechanism 30 can switch the transmission state from the traveling transmission shaft 26 to the main differential gear mechanism 40, that is, the transmission direction to the rear wheel 5 that is the main drive wheel.

  The forward / reverse switching mechanism 30 is supported by the traveling system transmission shaft 26, and includes a housing 31, a forward drive member 32F, a forward drive gear 33F, a reverse drive member 32R, and a reverse drive gear 33R. Furthermore, it comprises a forward friction plate group (not shown) and a reverse friction plate group.

  In the forward / reverse switching mechanism 30, the housing 31 is supported by the traveling system transmission shaft 26 so as not to rotate relative to the traveling system transmission shaft 26. Is supported so as to be relatively rotatable. The forward drive gear 33F is supported by the forward drive member 32F so as not to be relatively rotatable, and the reverse drive gear 33R is supported by the reverse drive member 32R so as not to be relatively rotatable.

  And a forward / reverse switching actuator which is a hydraulic clutch comprising a forward friction plate group and a reverse friction plate group which are operated in accordance with the operation of an operation means such as a forward / reverse selector switch or a forward / reverse selector lever provided near the driver's seat 112, the power transmission from the housing 31 to the forward drive member 32F can be selectively engaged or released, and the power transmission from the housing 31 to the reverse drive member 32R can be selectively engaged or released. Thus, the forward drive member 32F or the reverse drive member 32R can be interlocked with the traveling system transmission shaft 26.

  Further, a main drive wheel output shaft 35 disposed substantially parallel to the traveling system transmission shaft 26 is extended in the front-rear direction, and a ring gear 41 of the differential gear mechanism 40 is interlocked and connected to the rear end portion thereof. The forward driven gear 36F and the reverse driven gear 36R are supported so as not to rotate relative to each other.

  The forward drive gear 36F is engaged with the forward drive gear 33F, the reverse drive gear 36R is engaged with the reverse drive gear 33R via the transmission gear 49, and the forward drive member 32F and the reverse drive member 32R are engaged. The main differential gear mechanism 40 is interlocked with and connected to the main drive wheel output shaft 35. The transmission gear 49 is supported by a sub-drive wheel transmission shaft 48 that forms a traveling system sub-transmission path so as not to be relatively rotatable.

  A zero point detection gear 34 is engaged with the reverse drive gear 36R, and the zero point detection gear 34 detects whether or not the traveling speed of the work vehicle 1 is zero.

  Here, between the forward drive member 32F and the main drive wheel output shaft 35, a gear-meshing type sub-transmission mechanism 37 is used in the present embodiment so as to be able to perform a two-stage shift. Yes. However, it is also possible to configure so that three or more speeds can be changed.

  The auxiliary transmission mechanism 37 includes a forward drive high speed gear 33F (H) and a forward drive low speed gear 33F (L) that act as the forward drive gear 33F, and a forward driven high speed gear that acts as the forward driven gear 36F. 36F (H), a forward driven low-speed gear 36F (L), and a traveling system shifter 38 are provided.

  In this subtransmission mechanism 37, the forward drive high speed gear 33F (H) and the forward driven high speed gear 36F (H) are meshed, and the forward drive low speed gear 33F (L) and the forward driven low speed gear 36F (L). The forward-side driven high-speed gear 36F (H) and the forward-side driven low-speed gear 36F (L) can be selectively engaged with the main drive wheel output shaft 35 by the traveling system shifter 38.

  The traveling shifter 38 is driven by a sub-shift actuator 113 such as a cylinder or a motor that is operated in accordance with the operation of the sub-shift operation means 104 such as a sub-shift lever or a sub-shift switch provided near the driver's seat or a control described later. The sub-transmission mechanism 37 is configured to be switchable between a high speed stage and a low speed stage.

  In other words, the traveling system shifter 38 is slid by the operation of the auxiliary transmission operating means 104 or the operation of the auxiliary transmission actuator 113 based on the control described later, and the forward driven high speed gear 36F (H) is connected to the main drive wheel output shaft 35. When engaged, the gear is shifted to the high speed side, and when the forward driven low-speed gear 36F (L) is engaged, the gear is shifted to the low speed side, and the shift power is output to the main drive wheel output shaft 35. It has become.

  Also, the left and right output shafts 42 of the main differential gear mechanism 40 that are linked to the main drive wheel output shaft 35 are linked and connected to the axle 43 of the rear wheel 5 via a transmission gear train. The left and right output shafts 42 of the main differential gear mechanism 40 are each provided with a traveling system brake mechanism 45 so that the traveling system brake mechanism 45 can apply a braking force to each output shaft 42 independently.

  With such a configuration, when power transmission from the housing 31 to the forward drive member 32F is engaged in the forward / reverse switching mechanism 30 by the operation of the forward / reverse switching actuator 112 according to the operation of the operation means, The forward / reverse switching mechanism 30 is moved forward, the forward drive member 32F is rotated together with the traveling transmission shaft 26 via the housing 31, and the rotation is shifted by the subtransmission mechanism 37 and then the main drive. It is transmitted to the wheel output shaft 35, and then transmitted from the output shaft 42 of the main differential gear mechanism 40 to the axle 43, so that the rear wheel 5 is rotated so that the work vehicle 1 travels in the forward direction. .

  Conversely, when the power transmission from the housing 31 to the reverse drive member 32R is engaged by the operation of the forward / reverse switching actuator 112 according to the operation of the operating means, the forward / reverse switching mechanism 30 enters the reverse state, and the reverse drive The side drive member 32R is rotated together with the traveling system transmission shaft 26 via the housing 31, and the rotation is driven by the reverse drive gear 33R, the transmission gear 49, and the reverse drive gear 36R. Then, the transmission is transmitted from the output shaft 42 of the main differential gear mechanism 40 to the axle 43, and the rear wheel 5 is rotated so that the work vehicle 1 travels in the reverse direction.

  Further, the power transmission from the housing 31 to the forward drive member 32F is released by the operation of the forward / reverse switching actuator 112 according to the operation of the operation means, and the power transmission from the housing 31 to the reverse drive member 32R is released. When released, the forward / reverse switching mechanism 30 is in a neutral state, the rotation of the traveling system transmission shaft 26 is not transmitted to the axle 43, and the work vehicle 1 stops.

  In the travel system sub-transmission path, a sub-drive wheel transmission shaft 48 arranged substantially parallel to the travel system transmission shaft 26 extends in the front-rear direction and is interlocked and connected to the sub-drive wheel switching mechanism 50. Yes. The auxiliary drive wheel switching mechanism 50 can selectively switch between a rear wheel two-wheel drive state, a front-rear wheel constant-speed four-wheel drive state, and a front wheel acceleration four-wheel drive state.

  The auxiliary driving wheel switching mechanism 50 is supported by the traveling system auxiliary output shaft 60, and includes a housing 51, a constant speed transmission member 52 (L), a constant speed side driven gear 53 (L), and a speed increasing transmission member. 52 (H), a speed increasing side driven gear 53 (H), a constant speed side friction plate group (not shown), and a speed increasing side friction plate group.

  In the auxiliary drive wheel switching mechanism 50, the housing 51 is supported on the traveling system auxiliary output shaft 60 so as not to be relatively rotatable, and the constant speed transmission member 52 (L) and the speed increasing transmission member 52 (H) are arranged in front of and behind the housing 51. It is rotatably supported by the traveling system auxiliary output shaft 60 on both sides. The constant speed side driven gear 53 (L) is supported by the constant speed transmission member 52 (L) so as not to be relatively rotatable, and the speed increasing side driven gear 53 (H) is supported by the speed increasing transmission member 52 (H) so as not to be relatively rotatable. Has been.

  Then, the constant speed transmission member 52 (L) is moved from the constant speed transmission member 52 (L) to the housing by an actuator which is a hydraulic clutch including a constant speed friction plate group and an acceleration speed friction plate group that operate according to the operation of the operation means provided near the driver seat. The power transmission to 51 can be selectively engaged or released, and the power transmission from the speed increasing transmission member 52 (H) to the housing 51 can be selectively engaged or released, so that the constant speed transmission can be achieved. The member 52 (L) or the speed increasing transmission member 52 (H) can be interlocked and connected to the traveling system sub-output shaft 60.

  The sub drive wheel transmission shaft 48 is arranged substantially parallel to the traveling system sub output shaft 60, and the transmission gear 49 is supported at the rear end thereof so as not to be relatively rotatable. The gear 55 (L) and the speed increasing side drive gear 55 (H) are supported so as not to be relatively rotatable.

  The constant speed side drive gear 55 (L) is meshed with the constant speed side driven gear 53 (L), the speed increasing side drive gear 55 (H) is meshed with the speed increasing side driven gear 53 (H), The constant speed transmission member 52 (L) and the speed increasing transmission member 52 (H) are interlocked to the auxiliary drive wheel transmission shaft 48.

  Further, the traveling system sub-output shaft 60 is linked to a sub-differential gear mechanism 65 in the front axle case via a transmission shaft 61 and the like. The left and right output shafts 66 of the sub differential gear mechanism 65 are linked to the axles 67 of the front wheels 3.

  With such a configuration, when the work vehicle 1 is traveling in the forward direction, as described above, the forward / reverse switching mechanism 30 causes the forward drive member 32F to drive the main drive wheel output shaft via the auxiliary transmission mechanism 37. The transmission power transmitted to 35 is transmitted to the sub drive wheel transmission shaft 48 via the reverse drive gear 36R and the transmission gear 49.

  Conversely, when the work vehicle 1 is traveling in the reverse direction, the rotation transmitted to the reverse drive member 32R by the forward / reverse switching mechanism 30 as described above is transmitted to the reverse drive gear 33R and the transmission. It is transmitted to the auxiliary drive wheel transmission shaft 48 via the gear 49.

  Then, the power transmission from the constant speed transmission member 52 (L) to the housing 51 is released by the auxiliary drive wheel switching mechanism 50, and the power transmission from the speed increasing transmission member 52 (H) to the housing 51 is released. In this case, the power transmission from the auxiliary drive wheel transmission shaft 48 to the travel system sub output shaft 60 is cut off, and the work vehicle 1 is in a two-wheel drive state.

  When the power transmission from the constant speed transmission member 52 (L) to the housing 51 is engaged by the operation of the actuator and the power transmission from the speed increase transmission member 52 (H) to the housing 51 is released, the travel system The sub output shaft 60 is rotated synchronously with the main drive export force shaft 35 so that the work vehicle 1 is in a constant speed four-wheel drive state.

  When the power transmission from the constant speed transmission member 52 (L) to the housing 51 is released and the power transmission from the speed increase transmission member 52 (H) to the housing 51 is engaged by the operation of the actuator, the travel system The sub output shaft 60 is rotated at a speed higher than that of the main drive export force shaft 35, so that the work vehicle 1 is brought into a speed increased 4WD state.

  In the PTO transmission path, power transmission from the engine 6 to the PTO shaft 88 can be selectively engaged or interrupted by the PTO clutch mechanism 70. The PTO clutch mechanism 70 is supported by a PTO clutch shaft 75, and includes a PTO drive side member 71, a clutch housing 72, and a PTO friction plate group (not shown).

  In the PTO clutch mechanism 70, the PTO drive side member 71 is supported by the PTO clutch shaft 75 so as to be relatively rotatable, and the clutch housing 72 is supported by the PTO clutch shaft 75 so as not to be relatively rotatable. Then, the power transmission from the PTO drive side member 71 to the clutch housing 72 is selectively engaged or disengaged by an actuator that is a hydraulic clutch composed of a PTO friction plate group that operates in response to an operation of an operation means provided near the driver's seat. It can be released.

  The PTO clutch shaft 75 disposed substantially parallel to the constant speed output shaft 16 extends in the front-rear direction, and the PTO drive side member 71 on the PTO clutch shaft 75 is engaged with the constant speed gear 18, The engine 6 is linked and connected. Further, the PTO clutch mechanism 70 is provided with a PTO brake mechanism 73 that operates contrary to this.

  A PTO transmission shaft 78 is coaxially connected to the PTO clutch shaft 75 so as not to rotate relative to the axis, and a PTO transmission shaft 79 is arranged substantially parallel to the PTO transmission shaft 78 and extends in the front-rear direction. Has been. Between the PTO transmission shaft 78 and the PTO transmission shaft 79, a multi-stage transmission can be performed by the PTO multi-stage transmission mechanism 80.

  The PTO multi-stage transmission mechanism 80 includes a plurality of PTO drive side transmission gears 81, a plurality of PTO driven side transmission gears 82, and a PTO transmission shifter 83. In this PTO multi-stage transmission mechanism 80, a plurality of PTO drive side transmission gears 81 are supported on the PTO transmission shaft 78 in a relatively non-rotatable manner, and a plurality of PTO driven side transmission gears 82 are supported on the PTO transmission shaft 79 so as to be relatively rotatable and relatively rotatable. Has been.

  The plurality of PTO drive side transmission gears 81 and the plurality of PTO driven side transmission gears 82 are meshed directly or indirectly, and the PTO transmission shifter 83 selects the plurality of PTO driven side transmission gears 82 as the PTO transmission shaft 79. Can be engaged.

  In the present embodiment, the PTO multi-stage speed change mechanism 80 enables a total of five speeds including four forward rotation speeds and one reverse rotation speed. The PTO multi-stage speed change mechanism 80 includes forward rotation side first to fourth speed drive gears 81F (1) to 81F (4) and a reverse rotation side drive gear 81R that act as the plurality of PTO drive side transmission gears 81, Forward-side first to fourth-stage driven gears 82F (1) to 82F (4) and reverse-side driven gear 82R acting as the PTO driven side transmission gear 82, and the first / fourth acting as the PTO transmission shifter 83. A stage shifter 83F (1-4), a second / third stage shifter 83F (2-3), and a reverse shifter 83R are provided.

  In the PTO multi-stage speed change mechanism 80, the forward rotation side first to fourth speed driven gears 82F (1) to 82F (4) are supported by the PTO speed change shaft 79 so as to be relatively rotatable, respectively, A first-stage driven gear 82F (1) and the forward rotation-side fourth-stage driven gear 82F (4) are arranged to face each other, and the forward-rotation-side second-stage driven gear 82F (2) and the forward-rotation-side third-stage driven gear. The gear 82F (3) is disposed opposite to the gear 82F (3).

  These forward rotation side first to fourth stage driven gears 82F (1) to 82F (4) are respectively supported on the forward rotation side first to fourth stage drive gears 81F (non-rotatably supported by the PTO transmission shaft 78). 1) to 81F (4). The reverse drive gear 81R is meshed with the reverse drive gear 82R via an idle gear 84.

  The first / fourth stage shifter 83F (1-4) is disposed between the forward rotation side first stage driven gear 82F (1) and the forward rotation side fourth stage driven gear 82F (4), and The second / third stage shifter 83F (2-3) is disposed between the forward rotation side second stage driven gear 82F (2) and the forward rotation side third stage driven gear 82F (3). .

  The first / fourth stage shifter 83F (1-4) selectively allows the forward rotation side first stage driven gear 82F (1) or the forward rotation side fourth stage driven gear 82F (4) to selectively move to the PTO speed change shaft. 79 can be engaged. By the second / third stage shifter 83F (2-3), the forward rotation side second stage driven gear 82F (2) or the forward rotation side third stage driven gear 82F (3) is selectively used by the PTO transmission shaft. 79 can be engaged. Further, the reverse rotation side driven gear 82R is selectively engageable with the PTO transmission shaft 79 by the reverse rotation shifter 83R.

  Then, the first / fourth stage shifter 83F (1-4) and the second / third stage shifter 83F (2-3) according to the operation of the operation means such as a PTO shift lever provided near the driver's seat. ) And the reverse shifter 83R can be operated. By the operation, any one of the first to fourth forward driven gears 82F (1) to 82F (4) and the reverse driven gear 82R can be applied to the PTO transmission shaft 79. When the gears are engaged, a shift corresponding to this is performed, and the shift power is output to the transmission shaft 85.

  The transmission shaft 85 is coaxially connected to the PTO transmission shaft 79 so as to be relatively rotatable around the axis thereof, and the transmission shaft 85 is connected to the PTO shaft 88 via a transmission gear train so that the transmission power is transmitted to the work vehicle. 1 can be output to a work machine or the like attached to the machine 1.

  Next, the control of the transmission 4 when the auxiliary transmission mechanism 37 is shifted will be described.

  As shown in FIG. 3, the work vehicle 1 or its transmission 4 includes a tilt angle for detecting the tilt angle of the movable swash plate 15 of the output adjusting member provided in the hydraulic pump 11 of the hydrostatic continuously variable transmission mechanism 10. The sub-shift operating means 104 for switching the shift stage of the detection means 101, the sub-transmission mechanism 37, and the sub-shift detection means 103 for detecting the shift stage of the sub-transmission mechanism 37 switched by the operation of the sub-shift operation means 104. In addition, a traveling speed detection unit 102 that detects a traveling speed is provided, and these are connected to the control unit 100.

  Further, the work vehicle 1 or its transmission 4 includes a shift actuator 111 that controls the movable swash plate 15 of the output adjustment member provided in the hydraulic pump 11 of the hydrostatic continuously variable transmission mechanism 10 by tilting it, A forward / reverse switching actuator 112 that switches the forward switching mechanism 30, a sub-shifting actuator 113 that operates the traveling system shifter 38 of the sub-transmission mechanism 37 to shift the sub-transmission mechanism 37, and the like are provided in the control means 100. It is connected. The control unit 100 includes a CPU, RAM, ROM, and the like, and a control program is stored in the ROM.

  In the present embodiment, the tilt angle detecting means 101 detects the rotation angle of the control shaft of the output adjusting member provided in the hydraulic pump 11 by the hydrostatic continuously variable transmission mechanism 10 by a potentiometer, a rotary encoder or the like. Thus, the tilt angle of the movable swash plate 15 having the control axis as a rotation axis is detected.

  The sub-shift operating means 104 is constituted by a switch, and when the shift switch is pushed, the sub-shift actuator 113 is operated so as to be a shift stage corresponding to the operation, and the shift stage of the sub-transmission mechanism 37 is changed. It can be switched.

  The sub-shift detection unit 103 is configured to detect the shift stage of the sub-transmission mechanism 37, here, the high and low two stages by detecting the operation of the sub-shift operation unit 104. . If the sub-shift operating means 104 is a lever, the operation position of the sub-shift lever is detected by a potentiometer or the like disposed at the base thereof, so that the gear position of the sub-transmission mechanism 37 is determined from that position. Configured to detect.

  The speed change actuator 111 is composed of a hydraulic cylinder or the like, and is operated by an electromagnetic valve that is switched based on a control signal output from the control means 100 corresponding to the operation position of the main speed change lever, and is a movable swash plate 15 of the output adjusting member. Is inclined so that the hydrostatic continuously variable transmission mechanism 10 can be shifted. During this shift, the tilt angle detected by the tilt angle detecting means 101 is controlled so as to become the tilt angle set by the control means 100.

  The auxiliary transmission actuator 113 is constituted by a hydraulic cylinder or the like, and is operated by an electromagnetic valve that is switched based on a control signal output from the control means 100 in response to the operation of the auxiliary transmission switch. 38 is slid to engage or release the power transmission state between the main drive wheel output shaft 35 and the forward driven low speed gear 36F (H) or the forward driven low speed gear 36F (L). The sub-transmission mechanism 37 can be shifted to either one of the high and low two stages by switching the shift stage from the low speed stage to the high speed stage or from the high speed stage to the low speed stage.

  The forward / reverse switching actuator 112 is constituted by a hydraulic clutch, and is operated by an electromagnetic valve that is switched based on a control signal output from the control means 100 corresponding to the operation position of the forward / reverse switching switch. The power transmission between the housing 31 and the forward drive member 32F or the reverse drive member 32R is engaged or released so that the forward state, the reverse state, and the neutral state can be switched.

  However, the actuator is not limited to a hydraulic cylinder or a hydraulic clutch, but can be constituted by an electric motor, an electric cylinder, an electromagnetic clutch, or the like, and is not limited.

  In such a configuration, the control unit 100 performs the following control.

  When the work vehicle 1 is traveling forward in a state where the speed of the auxiliary transmission mechanism 37 is set to the low speed, the auxiliary transmission operating means 104 is operated to the high speed side as shown in FIG. S11), and a switching instruction signal for switching the gear position of the subtransmission mechanism 37 from the low speed stage to the high speed stage is input to the control means 100, and the travel speed at the time of operation of the subtransmission operation means 104 is detected as the travel speed detection. It is detected by the means 102 (step S12).

  Subsequently, the forward / reverse switching actuator 112 is actuated, and in the forward / reverse switching mechanism 30, the housing 31, the forward drive member 32F, and the reverse drive member 32R are relatively rotatable, and the forward / reverse switching mechanism 30 is operated by the work vehicle. The traveling drive is stopped from the forward state in which 1 is moved forward, that is, the forward / reverse switching mechanism 30 is switched to the neutral state in which the power transmission is cut off (step S13).

  When the forward / reverse switching mechanism 30 is switched to the neutral state, the transmission actuator 111 is actuated, and in the hydrostatic continuously variable transmission mechanism 10, the movable swash plate 15 of the output adjustment member is, as shown in FIG. The vehicle is tilted from the current swash plate position A1 to the swash plate position B1 so that the traveling speed is equal to the arbitrary speed V1 before and after the gear shift switching by 37. In other words, the traveling speed detected by the traveling speed detecting means 102 is equal to the traveling speed based on the output of the axle 43 in a state where the shift stage of the auxiliary transmission mechanism 37 is switched from the low speed stage to the high speed stage. The gear ratio of the hydrostatic continuously variable transmission mechanism 10 is changed (step S14).

  Then, the sub-transmission actuator 113 is actuated, and in the sub-transmission mechanism 37, the main drive wheel output shaft 35 and the forward driven low-speed gear 36F (L) are relatively rotatable by the traveling system shifter 38, while the forward-side driven high speed. The gear 36F (H) is made relatively incapable of rotation, the power transmission between the main drive wheel output shaft 35 and the forward driven high speed gear 36F (H) is engaged, and the speed of the subtransmission mechanism 37 is set to the low speed. To the high speed stage (step S15).

  Thereafter, the forward / reverse switching actuator 112 is actuated, and in the forward / reverse switching mechanism 30, the housing 31 and the forward drive member 32F or the reverse drive member 32R are not allowed to rotate relative to each other. The state is switched to the forward state (step S16). Thus, during the forward traveling of the work vehicle 1, the sub-transmission mechanism 37 is shifted from the low speed side to the high speed side while the traveling speed before and after that is maintained substantially constant. Thereafter, in a state in which the sub-speed stage is switched to the high speed stage, the speed is changed until the speed ratio instructed by the operating means such as the main speed change lever is reached (each traveling speed can be set at the high speed stage and the low speed stage). The target speed ratio is determined by operating the operating means such as the main speed change lever, and the movable swash plate 15 of the output adjusting member is rotated so as to correspond to it.

  On the other hand, when the work vehicle 1 is traveling forward with the speed of the auxiliary speed change mechanism 37 set to the high speed, the auxiliary speed change operating means 104 is operated to the low speed side as shown in FIG. When this is done (step S21), a switching instruction signal for switching the gear position of the subtransmission mechanism 37 from the high speed stage to the low speed stage is input to the control means 100, and the travel speed at the time of operation of the subtransmission operation means 104 is input. Is detected by the traveling speed detecting means 102 (step S22).

  Subsequently, whether or not the traveling speed detected by the traveling speed detecting means 102 is equal to or less than the maximum traveling speed V2 (within the shift region) when the shift stage of the subtransmission mechanism 37 is at the low speed stage, that is, the subshift. Even when the speed of the mechanism 37 is switched from the high speed to the low speed, it is determined whether or not the speed can be maintained within the speed change region of the hydrostatic continuously variable transmission 10 (step S23). If the traveling speed is equal to or less than the maximum traveling speed V2, the control is continued to step S25 described later.

  On the other hand, if the travel speed is higher than the maximum travel speed V2, the speed change actuator 111 is actuated, and in the hydrostatic continuously variable transmission mechanism 10, the movable swash plate 15 of the output adjusting member travels as shown in FIG. The hydrostatic continuously variable transmission mechanism 10 is tilted from the current swash plate position A3 to the swash plate position A2 so that the speed does not exceed the maximum traveling speed V2 when the auxiliary transmission mechanism 37 is at the low speed stage from the arbitrary speed V3. Is changed (step S24). That is, the work vehicle 1 is decelerated. Steps S22 and S23 are repeated until the travel speed reaches the maximum travel speed V2.

  When the traveling speed detected by the traveling speed detecting means 102 is equal to or lower than the maximum traveling speed V2 when the auxiliary transmission mechanism 37 is in the low speed stage, the forward / reverse switching actuator 112 is operated. The forward drive member 32F and the reverse drive member 32R are rotatable relative to each other, and the forward / reverse switching mechanism 30 is switched from a forward state in which the work vehicle 1 travels forward to a neutral state in which power transmission is cut off (step S25). .

  When the forward / reverse switching mechanism 30 is switched to the neutral state, the transmission actuator 111 is actuated, and in the hydrostatic continuously variable transmission mechanism 10, the movable swash plate 15 of the output adjustment member is, as shown in FIG. The current swash plate position A2 is tilted to the swash plate position B2 so that the traveling speeds coincide with each other at the maximum traveling speed V2 or lower than before and after the shift switching by 37. In other words, the travel speed detected by the travel speed detection means 102 is substantially equal to the travel speed based on the output of the axle 43 in a state where the shift speed of the auxiliary transmission mechanism 37 is switched from the high speed position to the low speed position. Thus, the gear ratio of the hydrostatic continuously variable transmission mechanism 10 is changed (step S26).

  Then, the sub-transmission actuator 113 is operated, and in the sub-transmission mechanism 37, the main drive wheel output shaft 35 and the forward-side driven low-speed gear 36F (L) are disabled relative to each other by the traveling system shifter 38, while the forward-side driven high speed. The gear 36F (H) is relatively rotatable, the power transmission between the main drive wheel output shaft 35 and the forward driven low-speed gear 36F (H) is engaged, and the speed of the auxiliary transmission mechanism 37 is set to the high speed. To the low speed stage (step S27).

  Thereafter, the forward / reverse switching actuator 112 is actuated, and in the forward / reverse switching mechanism 30, the housing 31 and the forward drive member 32F or the reverse drive member 32R are not allowed to rotate relative to each other. The state is switched to the forward state (step S28). Thus, during the forward traveling of the work vehicle 1, the subtransmission mechanism 37 is shifted from the high speed side to the low speed side so that the traveling speed before and after that is maintained substantially constant. Thereafter, in a state in which the sub shift stage is switched to the low speed stage, the speed is changed until the speed ratio designated by the operating means such as the main speed change lever is obtained. The target speed ratio is determined by operating the operating means such as the main speed change lever, and the movable swash plate 15 of the output adjusting member is rotated so as to correspond to it.

  Further, the switching of the gear position of the auxiliary transmission mechanism 37 as described above is performed by operating the auxiliary transmission operation means 104 for a certain time (for example, 0.16 seconds) or longer, so that the gear position of the auxiliary transmission mechanism 37 is changed from a low speed to a high speed. This is automatically performed when a switching instruction signal for switching from the high speed stage to the low speed stage is input to the control means 100. In other words, if the auxiliary speed change operation unit 104 is not operated for a certain time (for example, 0.16 seconds) or longer, there is a possibility that the auxiliary speed change operation unit 104 may be erroneously operated.

  As described above, the hydrostatic continuously variable transmission mechanism 10 including the hydraulic pump 11 and the hydraulic motor 12, the transmission actuator 111 that shifts the hydrostatic continuously variable transmission mechanism 10, and the auxiliary transmission that includes a plurality of shift stages. A mechanism 37, a sub-transmission actuator 113 that shifts the sub-transmission mechanism 37, a sub-transmission operation means 104 that switches the gear position of the sub-transmission mechanism 37, a forward / reverse switching mechanism 30 that switches a forward / backward state, In the transmission 4 of the work vehicle 1 including the forward / reverse switching actuator 112 for switching the forward / reverse switching mechanism 30, the traveling speed detecting means 102 for detecting the traveling speed, and the control means 100 for controlling them, the sub-shift operating means. When 104 is operated, the traveling speed is detected by the traveling speed detecting means 102, and the forward / reverse switching mechanism 30 is moved to the forward / reverse switching actuator. 12, the hydrostatic continuously variable transmission mechanism 10 is switched from the forward state or the reverse state to the neutral state, and the traveling speed of the sub-transmission mechanism 37 after the shift is shifted by the shift actuator 111 to the detected traveling speed. After shifting to match, the sub-transmission mechanism 37 is shifted by the sub-transmission actuator 113, and the forward / reverse switching mechanism 30 is switched from the neutral state to the forward or reverse state by the forward / reverse switching actuator 112. Accordingly, it is possible to shift the subtransmission mechanism 37 from the low speed side to the high speed side without stopping the work vehicle 1 even while traveling, and it is possible to suppress a shift shock that occurs at the time of the shift switching. Since either one of the hydraulic pump 11 and the hydraulic motor 12 of the hydrostatic continuously variable transmission mechanism 10 is a fixed capacity type, the cost can be reduced.

  Further, in the transmission 4 of the work vehicle 1, when the auxiliary transmission mechanism 37 is shifted from the high speed side to the low speed side, the detected traveling speed exceeds the shift region at the low speed stage of the auxiliary transmission mechanism 37. If the hydrostatic continuously variable transmission mechanism 10 is shifted to the low speed side by the speed change actuator 111 and the traveling speed reaches the maximum traveling speed at the low speed stage of the auxiliary transmission mechanism 37, the forward / reverse switching mechanism 30 Is switched from a forward or reverse drive state to a neutral state by the forward / reverse switching actuator 112, the auxiliary transmission mechanism 37 is shifted to a low speed by the auxiliary transmission actuator 113, and the forward / reverse switching mechanism 30 is neutralized by the forward / reverse switching actuator 112. By switching from the state to the forward state or the reverse state, the work vehicle 1 is not stopped even during traveling. The subtransmission mechanism 37 it is possible to shift to the low speed side from the high-speed side, the shift shock generated in the shift switching can be suppressed.

  Further, in the transmission 4 of the work vehicle 1, the shift stage switching of the auxiliary transmission mechanism 37 is automatically performed when the auxiliary transmission operation means 104 is operated for a predetermined time or more. An erroneous operation of the auxiliary transmission operation means 104 can be prevented.

The side view which showed the whole structure of the work vehicle provided with the transmission which concerns on one Example of this invention. The figure which showed the structure of the power transmission mechanism of a transmission. The block diagram which showed the structure of the control mechanism. The flowchart figure which showed the aspect of control in the case of shifting a subtransmission mechanism from the low speed side to the high speed side. The figure which showed the structure of the swash plate control in the case of shifting a subtransmission mechanism from the low speed side to the high speed side. The flowchart figure which shows the control method which showed the aspect of the control in the case of shifting a subtransmission mechanism from the high speed side to the low speed side. The figure which showed the structure of the swash plate control in the case of shifting a subtransmission mechanism from a high speed side to a low speed side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work vehicle 4 Transmission 10 Hydrostatic continuously variable transmission mechanism 11 Hydraulic pump 12 Hydraulic motor 30 Forward / reverse switching mechanism 37 Sub shift switching mechanism 100 Control means 102 Traveling speed detection means 104 Sub shift operation means 111 Shift actuator 112 Forward / reverse switching Actuator 113 Sub-shift actuator

Claims (3)

A hydrostatic continuously variable transmission mechanism having a hydraulic pump and a hydraulic motor, a transmission actuator for shifting the hydrostatic continuously variable transmission mechanism, a subtransmission mechanism having a plurality of shift stages, and a shift of the subtransmission mechanism A sub-shift actuator, sub-shift operating means for switching the shift speed of the sub-transmission mechanism, a forward / reverse switching mechanism for switching the forward / reverse state, a forward / reverse switching actuator for switching the forward / backward switching mechanism, and a traveling speed are detected. A speed change device for a work vehicle, comprising: a traveling speed detecting means that controls the control means;
When the sub-shift operation means is operated, a traveling speed is detected by a traveling speed detecting means, the forward / reverse switching mechanism is switched from a forward state or a reverse state to a neutral state, and the hydrostatic continuously variable transmission mechanism is After the sub-transmission mechanism is shifted so that the traveling speed at the speed stage after the shift matches the detected traveling speed, the sub-transmission mechanism is shifted, and the forward / reverse switching mechanism is moved from the neutral state to the forward state or the reverse state. A transmission for a work vehicle, characterized in that it is configured to switch to   When shifting the auxiliary transmission mechanism from the high speed side to the low speed side, if the detected traveling speed exceeds the speed change region at the low speed stage of the auxiliary transmission mechanism, the hydrostatic continuously variable transmission mechanism is When shifting to the low speed side and the traveling speed reaches the maximum traveling speed at the low speed stage of the auxiliary transmission mechanism, the forward / reverse switching mechanism is switched from the forward or reverse state to the neutral state, and the auxiliary transmission mechanism is set to the low speed stage. 2. The transmission for a work vehicle according to claim 1, wherein the transmission is shifted and the forward / reverse switching mechanism is switched from a neutral state to a forward state or a reverse state.   The shift of the work vehicle according to claim 1 or 2, wherein the shift of the sub-transmission mechanism is configured to be automatically performed when the sub-shift operation means is operated for a predetermined time or more. apparatus.

Images