JP5083969B2 - Continuously variable transmission output control structure - Google Patents

Description

  The present invention relates to a continuously variable transmission output control structure applied to a working vehicle in which a continuously variable transmission is inserted in a traveling system transmission path from a drive source to a drive wheel.

A continuously variable transmission such as HST (Hydraulic Static Transmission) includes a hydraulic pump body that is operatively rotated by rotational power from a drive source, and a hydraulic pressure that is operatively driven by hydraulic power from the hydraulic pump body. A motor main body, and at least one of the hydraulic pump main body or the hydraulic motor main body is a variable displacement type.
The HST as the continuously variable transmission further includes an output adjusting member that changes a suction / discharge amount of a variable displacement type member (hereinafter referred to as a variable displacement type member) of the hydraulic pump body or the hydraulic motor body. The rotation speed of the hydraulic motor body relative to the rotation speed of the hydraulic pump body can be changed steplessly by operating the output adjustment member.

By the way, there has been proposed a working vehicle configured to operate the output adjustment member of the HST via a main transmission actuator (see, for example, Patent Document 1).
Specifically, the working vehicle moves the HST, a main transmission operation member that can be manually operated, a main transmission operation detection sensor that detects an operation position of the main transmission operation member, and an output adjustment member of the HST. And a control device that controls the operation of the main transmission actuator based on an input signal from the main transmission operation detection sensor.

Such a working vehicle is configured such that the control device controls the operation of the main transmission actuator so that the vehicle speed corresponds to the operation position of the main transmission operation member.
For example, when the main transmission operation member is positioned at the vehicle stop position, the control device operates the main transmission actuator to position the output adjustment member at a position corresponding to the vehicle stop, whereby the working vehicle is It comes to stop.

  However, manufacturing errors may occur in the HST. Therefore, even though the main speed change operation member is positioned at a predetermined speed position and the control device positions the output adjusting member at a predetermined position via the main speed change actuator, There may occur a case where the actual vehicle speed does not become a speed corresponding to a predetermined speed position where the main speed change operating member is located.

  In particular, in a working vehicle in which an HMT (Hydraulic Mechanical Transmission) in which the HST and the planetary gear unit are combined is inserted in the traveling system transmission path, when the output adjustment member is located at a position other than the neutral position In a working vehicle configured so that the vehicle speed becomes zero, when a manufacturing error occurs in the HST, the working vehicle moves forward or backward despite the main transmission operation member being positioned at the vehicle stop position. Inconvenience can occur.

More specifically, a working vehicle equipped with the HMT may be configured such that the vehicle speed becomes zero when the output adjusting member is positioned at a position other than the neutral position in order to increase the shift width. .
For example, in a working vehicle having an HMT including an HST in which the output adjustment member can be operated in both forward and reverse directions and the planetary gear unit, the output adjustment member is positioned at a predetermined position in the reverse direction. When the HST outputs a predetermined number of revolutions in the reverse rotation direction, the vehicle speed is configured to be zero.

In such a working vehicle, in order to put the working vehicle in a stopped state (vehicle speed zero state), the output adjusting member must be pinpointed not at the neutral position but at the predetermined position in the reverse direction.
JP 2004-218687 A

  The present invention has been made in view of the above prior art, and the control device operates the main transmission actuator according to the operation of the main transmission operation member, thereby changing the output speed of the continuously variable transmission and changing the vehicle speed. A continuously variable transmission output control structure applied to a working vehicle configured to cause the vehicle to obtain a vehicle speed corresponding to an operation position of the main transmission operating member regardless of a manufacturing error of the continuously variable transmission. The object is to provide a simple continuously variable transmission output control structure.

To achieve the above object, a continuously variable transmission output control structure according to the present invention includes a hydraulic continuously variable transmission as a main transmission that is inserted in a traveling system transmission path from a drive source to a drive wheel, A planetary gear unit for synthesizing a synchronous output from the drive source and a shift output from the continuously variable transmission and outputting it from a combined output member, an artificially operable main transmission operation member, and an operation position of the main transmission operation member A main transmission operation detecting sensor for detecting the output, a main transmission actuator for moving the output adjusting member of the continuously variable transmission, a vehicle speed sensor for directly or indirectly detecting the rotational speed of the drive wheel, and the main transmission operation detection. A control device for inputting a target rotational speed of the driving wheel corresponding to an operation amount of the main transmission operating member by a sensor and performing operation control of the main transmission actuator based on the input signal. The continuously variable transmission output control structure applied to a work vehicle, the continuously variable transmission and the planetary gear unit, the synthesized output the shift output of the continuously variable transmission is in the reverse direction when a predetermined rotational speed The rotational speed of the composite output member increases as the rotational speed of the member becomes zero and the speed change output of the continuously variable transmission increases from the predetermined rotational speed in the reverse rotation direction to a predetermined rotational speed in the forward rotation direction. The control device has a normal control mode, an initial adjustment mode for adjusting a relationship between an output of the continuously variable transmission and an operation amount of the main transmission operation member, and the initial adjustment mode. in, operation wherein the extent that transmission output of the continuously variable transmission is a forward direction, said main transmission actuator such that the rotational speed of the drive wheel becomes a predetermined first speed based on the vehicle speed sensor So, stores the operation control quantity at that time as a first operation control amount, to the extent that the transmission output of the continuously variable transmission is the reverse direction, the rotational speed of the driving wheel based on the vehicle speed sensor The main speed change actuator is operated so as to be a predetermined second speed different from the first speed, the operation control amount at that time is stored as a second operation control amount, and based on the first and second operation control amounts By performing linear interpolation, a control function for the rotational speed change of the drive wheel with respect to the operation control amount of the main speed change actuator is calculated and stored, and the normal control mode calculates the initial adjustment mode. An operation control amount of the main transmission actuator corresponding to the target rotational speed input by the main transmission operation detection sensor is calculated using a control function, and the calculated The operation of the main transmission actuator is controlled based on an operation control amount.

According to the continuously variable transmission output control structure having the above configuration, when the main transmission operating member is manually operated, the target rotational speed of the driving wheel corresponding to the operation amount of the main transmission operating member is input to the control device as a signal. The output of the continuously variable transmission is controlled by controlling the main transmission actuator that moves the output adjusting member of the continuously variable transmission based on the signal.
Here, in the initial adjustment mode of the control device, the control function indicating the relationship between the output (vehicle speed) of the continuously variable transmission and the operation control amount of the main transmission actuator is calculated by actually running the work vehicle.
That is, the rotational speed of the driving wheel is set to a predetermined value based on a vehicle speed sensor that directly or indirectly detects the rotational speed of the driving wheel within a range where the speed change output of the continuously variable transmission is in the forward direction . An operation control amount of the main transmission actuator when the main transmission actuator is operated so as to be 1 speed is stored in the control device as a first operation control amount. Similarly, the rotational speed of the drive wheel is set to a predetermined second speed different from the first speed based on the vehicle speed sensor within a range where the speed change output of the continuously variable transmission is in the reverse direction. The operation control amount of the main transmission actuator when the main transmission actuator is operated is stored in the control device as the second operation control amount. By performing linear interpolation based on the obtained first and second operation control amounts by the control device, a control function of the rotational speed change (vehicle speed change) of the drive wheel with respect to the operation control amount of the main transmission actuator is calculated. Memorized.
In the normal control mode of the control device, the operation control amount of the main transmission actuator corresponding to the target rotational speed input by the main transmission operation detection sensor is calculated using the control function calculated in this way, and is calculated. The main speed change actuator is controlled to operate (ie, feedforward controlled) based on the operation control amount.

As described above, the relationship between the operation control amount of the main speed change actuator and the actual rotation speed of the drive wheel is held in advance as a control function in the initial adjustment mode, thereby corresponding to the operation amount of the main speed change operation member with a simple structure. It is possible to control the operation of the main transmission actuator so that there is no difference between the target rotational speed of the drive wheel and the actual rotational speed of the drive wheel.
Therefore, the actual vehicle speed of the working vehicle corresponds to the predetermined speed position where the main transmission operation member is positioned, even though the control device positions the output adjusting member at the predetermined position via the main transmission actuator. Therefore, the vehicle speed corresponding to the operation position of the main transmission operating member can be easily obtained regardless of the manufacturing error of the HST.

Preferably, the pre-Symbol second speed is zero.

In this case, the rotational speed of the drive wheel in one of two states to determine the control function is zero, i.e., the operation control of the main shift actuator in the stopped state of the working vehicle is employed.
As described above, since an actual measurement value can be obtained for the operation control amount of the main transmission actuator when the work vehicle is stopped, the main function for obtaining the stop state of the work vehicle in the normal control mode can be obtained by using the control function. An error in the operation control amount of the speed change actuator can be made as small as possible.
In particular, when the output adjusting member is located at a position other than the neutral position, a traveling vehicle is provided with an HMT in which the HST, which is the continuously variable transmission and the planetary gear unit, is interposed in the traveling transmission path. In the working vehicle configured so that the vehicle speed is zero, the operation control amount of the main transmission actuator can be obtained pinpointed when the working vehicle is stopped. Therefore, the main transmission operating member is positioned at the vehicle stop position. Nevertheless, it is possible to effectively prevent the disadvantage that the working vehicle moves forward or backward.

  Preferably, in the normal control mode, the control device controls the target rotational speed and the rotational speed of the driving wheel detected by the vehicle speed sensor when the main transmission actuator is controlled to operate based on the control function. And the main transmission actuator is feedback-controlled so that the difference is eliminated.

In this case, in the normal control mode of the control device, in addition to the feedforward control of the main transmission actuator based on the control function, the target rotation speed corresponding to the operation amount of the main transmission operation member and the actual rotation speed of the driving wheel (vehicle speed) The main transmission actuator is feedback-controlled by the control device in the direction in which) matches.
Thus, by performing the feedback control, the desired vehicle speed (target rotational speed) and the actual vehicle speed can be made to coincide with each other with high accuracy, and more optimal output control for the main transmission actuator can be performed.
Further, by performing the feedback control after performing the feedforward control, it is possible to perform the control to the appropriate value more quickly than the case where only the feedback control is performed.

According to the continuously variable transmission output control structure according to the present invention, the relationship between the operation control amount of the main transmission actuator and the actual rotational speed of the driving wheel is held in advance as a control function in the initial adjustment mode, thereby simplifying the operation. It is possible to control the operation of the main transmission actuator so that there is no difference between the target rotational speed of the driving wheel corresponding to the operation amount of the main transmission operating member and the actual rotational speed of the driving wheel.
Therefore, the actual vehicle speed of the working vehicle corresponds to the predetermined speed position where the main transmission operation member is positioned, even though the control device positions the output adjusting member at the predetermined position via the main transmission actuator. Thus, it is possible to prevent the occurrence of a state where the speed is not reached, and to easily obtain the vehicle speed corresponding to the operation position of the main transmission operating member regardless of the manufacturing error of the continuously variable transmission.

A preferred embodiment of a working vehicle to which a continuously variable transmission output control structure according to the present invention is applied will be described below with reference to the accompanying drawings.
FIG. 1 shows a side view of a working vehicle 1 to which a continuously variable transmission output control structure according to an embodiment of the present invention is applied. FIG. 2 shows a schematic diagram of transmission in the working vehicle 1 of FIG.

As shown in FIGS. 1 and 2, the work vehicle 1 is a tractor to which a work machine can be attached.
Specifically, the working vehicle 1 includes a vehicle frame 5, a drive source 10 supported by the vehicle frame 5, and a transmission 100 supported by the vehicle frame 5 in a state of being arranged in series with the drive source 10. ing.

The transmission 100 is a travel system transmission path that transmits power input from the drive source 10 via the transmission shaft 15 (see FIG. 2) to the drive wheels (in the form shown, after acting as a main drive wheel). A traveling system main transmission path for transmitting power to the wheels 30 and a traveling system auxiliary transmission path for transmitting power to the front wheels 35 acting as auxiliary driving wheels), and the power from the drive source 10 via the PTO shaft 260. And a PTO transmission path that outputs to the outside.
The transmission 100 receives an output from the drive source 10 as a traveling transmission path, and is a continuously variable transmission that functions as a main transmission, an HST 110, a synchronous output from the drive source 10, and a shift from the HST 110. A planetary gear unit 150 that receives an output and is combined with the HST 110 to form an HMT, a traveling system hydraulic switching unit 300 that switches a transmission path of rotational power output from the planetary gear unit 150, and the traveling system hydraulic pressure. Sub-transmission device 200 that functions as a mechanical multi-stage transmission that shifts the rotational power from type switching unit 300, and a differential gear that differentially transmits the rotational power from sub-transmission device 200 to a pair of main drive axles. Unit 400.

  As shown in FIG. 2, the HST 110 includes a synchronous output shaft (pump shaft) 111 operatively connected to the transmission shaft 15, a hydraulic pump body 112 supported on the synchronous output shaft 111 so as not to rotate relative thereto, A synchronous output shaft 111 that outputs the power of the hydraulic pump main body 112, a hydraulic motor main body 114 that is fluidly connected to the hydraulic pump main body 112, and a speed change output shaft (motor shaft) 113 that outputs the rotational power of the hydraulic motor main body 114. And.

At least one of the hydraulic pump main body 112 and the hydraulic motor main body 114 is a variable displacement type. In the present embodiment, as shown in FIG. 2, the hydraulic pump main body 112 is a variable displacement type.
Therefore, the HST 110 includes an output adjusting member 115 including a movable swash plate that changes the amount of oil supplied and discharged from the hydraulic pump main body 112 and a control shaft that tilts the movable swash plate in addition to the above configuration.
The control shaft extends in a direction orthogonal to the synchronous output shaft 111 and has one end extending outward. The movable swash plate is connected to the other end of the control shaft via a connecting arm, and tilts according to the rotation of the control shaft around the axis.

  As shown in FIG. 2, the planetary gear unit 150 is configured to synchronize output of the HST 110 via the synchronous output shaft 111 (or a rotational shaft that is coaxially connected to the synchronous output shaft 111 and is connected so as not to rotate relative to the axis). And the shift output of the HST 110 is input via the shift output shaft 113 (or a rotation shaft that is coaxially connected to the shift output shaft 113 and connected to the shift output shaft 113 so as not to rotate relative to the axis). It is configured to be able to synthesize and output.

  More specifically, the planetary gear unit 150 is engaged with the sun gear 151 that receives the synchronization output of the synchronization output shaft 111, one or more planetary gears 152 that mesh with the sun gear 151, and the planetary gear 152. An internal gear 153 and a composite output member (carrier) 154 that outputs a revolution component of the planetary gear 152 around the sun gear 151 are provided.

The sun gear 151 is fixed to a hollow synchronous transmission shaft 157 so as not to rotate relative to the axis. A synchronization transmission gear 158 is fixed to the front end portion of the synchronization transmission shaft 157 so as not to rotate relative to the axis. The synchronous transmission gear 158 meshes with a synchronous input gear 116 fixed to the synchronous output shaft 111 so as not to rotate relative to the axis. As a result, a synchronous output synchronized with the drive source 10 (a constant speed output when the output of the drive source 10 is constant) is transmitted to the sun gear 151.
The internal gear 153 is fixed to a hollow transmission transmission shaft 159 that is loosely fitted coaxially with the synchronous transmission shaft 157 so as not to rotate relative to the axis. A transmission transmission gear 160 is fixed to the front end of the transmission transmission shaft 159 so as not to rotate relative to the axis, and meshes with a transmission input gear 117 fixed to the transmission output shaft 113 so as not to rotate relative to the axis. As a result, the shift output of the HST 110 is transmitted to the internal gear 153.
The composite output member 154 has a front end that is loosely fitted coaxially with the synchronous transmission shaft 157, and a forward-side low-speed transmission gear 161 is fixed to the rear end so as not to rotate relative to the axis.

The traveling system hydraulic conversion unit 300 is configured to be able to switch the transmission path of the rotational power from the planetary gear unit 150.
In the present embodiment, the traveling hydraulic switching unit 300 receives rotational power operatively input from the planetary gear unit 150 via a forward low speed path, a forward high speed path, or a reverse path that is selectively coupled. , And can be transmitted to the composite output shaft 301.
More specifically, the traveling hydraulic conversion unit 300 outputs the combined output shaft 301 (in this embodiment, the hollow synchronous transmission shaft 157 and the rotational output power) to the sub transmission 200 that follows. The forward-side clutch housing 302 and the reverse-side clutch housing 303 supported on the synthetic output shaft 301 so as not to rotate relative to each other about the axis, and the forward-side clutch housing 302 cannot relatively rotate about the axis. Further, the forward-side high-speed driven member 3042H and the forward-side low-speed driven member 3042L instructed to be slidable in the axial direction, and the reverse-side driven supported by the reverse-side clutch housing 303 so as not to be relatively rotatable around the axis and slidable in the axial direction. A member 3042R and a forward-side high-speed drive member 3041H operatively connected to the planetary gear 152; A forward-side high-speed drive member 3041H that can be selectively engaged or disengaged with the forward-side high-speed driven member 3042H by the action of hydraulic pressure, and a forward-side low-speed drive operatively connected to the composite output member 154 A member 3041L, which is a forward-side low-speed drive member 3041L that can selectively take an engaged state or a non-engaged state with respect to the forward-side low-speed driven member 3042L by the action of hydraulic pressure, and a reverse gear to the composite output member 154 A reverse drive member 3041R that is operatively connected via a row, and a reverse drive member 3041R that can selectively engage or disengage with the reverse drive member 3042R by the action of hydraulic pressure; have.

The forward clutch housing 302 has a base end portion supported so as not to be relatively rotatable about the axis of the combined output shaft 301 and a distal end portion extending radially outward from the combined output shaft 301, and the partition wall 302a. A peripheral wall 302b extending from the front end of the vehicle to the vehicle front-rear direction one side and the other side.
The forward side high speed driven member 3042H and the forward side low speed driven member 3042L are positioned on one side (here, the front side) and the other side (rear side) in the vehicle front-rear direction across the partition wall 302a. The peripheral wall 302b is supported so as not to rotate around the axis and to slide in the axial direction.
The reverse clutch housing 303 has a base end portion supported on the synthetic output shaft 301 so as not to rotate relative to the composite output shaft 301 and a distal end portion extending radially outward, and a vehicle front and rear from the distal end portion of the partition wall 303a. And a peripheral wall 303b extending to the other side in the direction (here, the rear side).
The reverse drive member 3042R is supported by the peripheral wall 303b so as not to rotate relative to the axis and to slide in the axial direction.

The forward high speed drive member 3041H is operatively connected to the planetary gear 152 as described above.
In the present embodiment, the forward drive high speed drive member 3041H is operatively connected to the planetary gear 152 via a forward drive high speed gear train.
As shown in FIG. 2, the forward-side high-speed gear train is non-rotatable relative to the forward-side high-speed first transmission shaft 155a that supports the planetary gear 152 so as not to rotate relative to the forward-side high-speed first transmission shaft 155a. A forward-side high-speed first gear 155b supported, a forward-side high-speed second gear 155c meshed with the forward-side high-speed first gear 155b, and a forward-side that supports the forward-side high-speed second gear 155c in a relatively non-rotatable manner. A high-speed second transmission shaft 155d.
The advancing high-speed drive member 3041H is supported by the advancing-side high-speed second transmission shaft 155d so as not to rotate relative to the advancing-side high-speed driven member 3042H and to be slidable in the axial direction.
The forward-side high-speed drive member 3041H and the forward-side high-speed driven member 3042H form a forward-side high-speed clutch 315H (see FIG. 4) that is selectively engaged or disengaged by the action of hydraulic pressure.
In the present embodiment, the forward-side high-speed first transmission shaft 155a is a hollow shaft into which the composite output member 154 is inserted so as to be relatively rotatable. The forward high speed second transmission shaft 155d is a hollow shaft into which the combined output shaft 301 is inserted.

The forward drive low speed drive member 3041L is operatively connected to the composite output member 154 as described above.
In this embodiment, the forward drive low speed drive member 3041L is operatively connected to the combined output member 154 via the forward drive low speed transmission gear 161.
Specifically, as shown in FIG. 2, the forward-side low-speed transmission gear 161 moves around the combined output shaft 301 arranged coaxially with the sun gear 151 according to the revolution of the combined output member 154 about the sun gear 151. The composite output shaft 301 is rotatably supported so as to revolve.
The forward drive low speed drive member 3041L is supported by the forward drive low speed transmission gear 161 so as not to rotate relative to the forward drive low speed driven member 3042L and to be slidable in the axial direction.
The forward-side low-speed drive member 3041L and the forward-side low-speed driven member 3042L form a forward-side low speed clutch 315L (see FIG. 4) that is selectively engaged or disengaged by the action of hydraulic pressure.

As described above, the reverse drive member 3041R is operatively connected to the composite output member 154 via the reverse gear train.
The reverse gear train is configured to transmit reverse power to the reverse drive member 3041R by using a forward low speed transmission gear 161.
Specifically, as shown in FIG. 2, the reverse gear train supports the reverse-side first gear 164 meshed with the forward-side low-speed transmission gear 161 and the reverse-side first gear 164 so as not to be relatively rotatable. The reverse drive shaft 163, the reverse second gear 165 supported by the reverse drive shaft 163 so as not to rotate relative to the reverse drive gear 163, the reverse gear 166 meshed with the reverse drive second gear 165, and the reverse gear 166. And a reverse-side third gear 162 that is supported by the combined output shaft 301 so as to be relatively rotatable.
The reverse drive member 3041R is supported by the reverse third gear 162 so as not to be rotatable relative to the reverse drive member 3042R and to be slidable in the axial direction.
The reverse drive member 3041R and the reverse drive member 3042R form a reverse clutch 315R (see FIG. 4) that is selectively engaged or disengaged by the action of hydraulic pressure.

In the present embodiment, the forward-side high-speed drive member 3041H and the forward-side high-speed driven member 3042H that form the forward-side high-speed clutch 315H are in the form of friction plates.
That is, the advance side high speed drive member 3041H is a drive side friction plate, and the advance side high speed driven member 3042H is a driven side friction plate.
Similarly, the forward-side low-speed drive member 3041L and the forward-side low-speed driven member 3042L that form the forward-side low-speed clutch 315L, and the reverse-side drive member 3041R and the reverse-side driven member that form the reverse-side clutch 315R. 3042R is also in the form of a friction plate.

The traveling system hydraulic pressure conversion unit 300 is configured so that the forward-side high-speed clutch 315H, the forward-side low-speed clutch 315L, and the reverse-side clutch 315R are selectively engaged by the action of hydraulic pressure, respectively. The forward side low-speed transmission state and the reverse transmission state are taken.
Specifically, when the traveling hydraulic conversion unit 300 enters the forward high speed transmission state (that is, when the forward high speed drive member 3041H and the forward high speed driven member 3042H are engaged), the planetary gear 152 A rotation component around the axis of the combined output member 154 is operatively transmitted to the combined output shaft 301.
When the traveling system hydraulic conversion unit 300 is in the forward-side low-speed transmission state (that is, when the forward-side low-speed drive member 3041L and the forward-side low-speed driven member 3042L are engaged), the sun gear of the combined output member 154 A rotation component around 151 is operatively transmitted to the combined output shaft 301.
When the traveling hydraulic conversion unit 300 is in the reverse transmission state (that is, when the reverse drive member 3041R and the reverse drive member 3042R are engaged), the sun gear around the combined output member 154 is obtained. A rotation component around 151 is operatively transmitted to the combined output shaft 301 through the reverse gear train.

  The rotational power selectively transmitted to the combined output shaft 301 in this way is transmitted to the drive wheels 30 via the auxiliary transmission 200 and the differential gear unit 400.

  Here, FIG. 3 shows the number of rotations of the composite output shaft 301 and the number of rotations of the transmission output shaft 113 (the number of rotations of the transmission shaft 15) when the input rotation number of the HST 110 to the hydraulic pump body 112 (the rotation number of the transmission shaft 15) is constant. The relationship figure with the motor output-shaft rotation speed of HST110 is shown.

In the present embodiment, the HMT and the traveling system hydraulic switching unit 300 are configured such that the output of the variable output of the HST 110 (the shift output shaft 113) is not zero but is a predetermined rotational speed M1 in the reverse direction (reverse rotation MAX <M1 < 0), the rotational speed of the composite output shaft 301 becomes zero (that is, the vehicle speed is zero), and the variable output of the HST 110 exceeds zero from M1 and reaches a predetermined rotational speed M2 ( While the speed is increased to 0 <M2 <Forward rotation MAX), the forward-side low-speed transmission state FL is reached, and the variable output of the HST 110 is decelerated from M2 to zero to the maximum reverse rotation speed (reverse rotation MAX). The forward side high speed transmission state FH, and the variable output of the HST 110 exceeds the zero from M1 to the maximum speed in the forward rotation direction (forward rotation MAX) so that the reverse side transmission state R is reached. It has been made.
By providing such a configuration, the forward shift range with respect to the operation amount to the HST 110 can be increased, and the tilt position of the movable swash plate of the HST 110 can be set in the forward low-speed transmission state FL used during work. Thus, the transmission efficiency of the HST 110 can be improved.

The sub transmission 200 is configured to shift the rotational power operatively transmitted from the combined output shaft 301 in multiple stages.
In the present embodiment, the sub-transmission device 200 is configured to perform a two-speed shift at a high speed and a low speed.
Specifically, as shown in FIG. 2, the auxiliary transmission device 200 includes a drive shaft 201 operatively connected to the combined output shaft 301, and a propeller shaft 206 disposed in parallel to the drive shaft 201. And a high-speed gear train and a low-speed gear train supported by the drive shaft 201 and the propeller shaft 206, and a shifter 209 that causes the high-speed gear train or the low-speed gear train to be in a power transmission state at a selected low level.

In the present embodiment, the drive shaft 201 is a hollow shaft that is extrapolated to a PTO transmission shaft 261 (described later) that is coaxially connected to the synchronous output shaft 111 and is connected so as not to rotate relative to the axis. The drive shaft 201 is operatively connected to the combined output shaft 301 via transmission gear trains 202 and 203.
The propeller shaft 206 is disposed coaxially with the combined output shaft 301.

The high-speed gear train includes a high-speed drive gear 204 supported by the drive shaft 201 and a high-speed driven gear 207 supported by the propeller shaft 206 in a state of being engaged with the high-speed drive gear 204. ing.
The low-speed gear train has a low-speed drive gear 205 supported by the drive shaft 201 and a low-speed driven gear 208 supported by the propeller shaft 206 in a state of being engaged with the low-speed drive gear 205. ing.
In the present embodiment, the high speed side drive gear 204 and the low speed side drive gear 205 are supported by the drive shaft 201 so as not to rotate relative to each other, and the high speed side driven gear 207 and the low speed side driven gear 208 are supported by the propeller shaft. 206 is supported so as to be relatively rotatable about an axis.
Therefore, in this embodiment, the shifter 209 is supported by the propeller shaft 206. Specifically, the shifter 209 is supported by the propeller shaft 206 between the high-speed driven gear 207 and the low-speed driven gear 208 so as not to rotate relative to the axis and to slide in the axial direction.

The shifter 209 is engaged with the high-speed driven gear 207 in a concave-convex manner according to the axial position of the propeller shaft 206, and is not engaged with both the high-speed driven gear 207 and the low-speed driven gear 208. In addition, it is configured so as to be able to engage with the low-speed driven gear 208 in a concave-convex manner.
In other words, when the shifter 209 is positioned at a high speed position with respect to the axial direction position of the propeller shaft 206, the auxiliary transmission 200 has a speed at which the rotational power of the drive shaft 201 corresponds to the gear ratio of the high speed gear train. Thus, a high-speed state is transmitted to the propeller shaft 206.
Further, when the shifter 209 is positioned at a low speed position with respect to the axial direction position of the propeller shaft 206, the auxiliary transmission device 200 is configured such that the rotational power of the drive shaft 201 corresponds to the gear ratio of the low speed gear train. Thus, a low-speed stage state transmitted to the propeller shaft 206 is established.
As the transition state when the shifter 209 shifts from the high speed position to the low speed position or from the low speed position to the high speed position, the shifter 209 is located between the high speed position and the low speed position with respect to the axial position of the propeller shaft 206. When positioned at the neutral position, the sub-transmission device 200 enters a power cut-off state in which power transmission from the drive shaft 201 to the propeller shaft 206 is cut off.

The propeller shaft 206 is operatively connected to the differential gear unit 400.
Specifically, a small bevel gear 402 that meshes with the input bevel gear 401 of the differential gear unit 400 for the main drive wheel is provided at the rear end of the propeller shaft 206.
In the present embodiment, the propeller shaft 206 is configured to output rotational power to the front wheels 35 that act as auxiliary drive wheels.
That is, a front wheel driving force take-out shaft 210 that outputs rotational power toward the front wheel 35 that is a sub driving wheel is disposed at the bottom of the transmission 100, and the propeller shaft 206 is connected to the transmission gear trains 211 and 212. Is operatively connected to the front wheel driving force take-out shaft 210 via

  The transmission 100 also includes a PTO transmission shaft 261 that transmits the synchronous output of the drive source 10 to the PTO shaft 260, and a PTO clutch device 75 that is interposed between the PTO transmission shaft 261 and the PTO shaft 260. And are provided.

Next, the hydraulic circuit of the transmission 100 will be described.
FIG. 4 shows a hydraulic circuit diagram in the working vehicle 1 of FIG.

As shown in FIG. 4, the working vehicle 1 has an auxiliary pump body that is operatively driven by the drive source 10 and acts as a hydraulic pressure source for various hydraulic power transmission units.
In the present embodiment, the working vehicle 1 includes first and second auxiliary pump bodies 51 and 52 as the auxiliary pump body.
That is, the working vehicle 1 includes the first and second auxiliary pump bodies 51 and 52, one end of which is fluidly connected to an oil source such as a transmission case and the other end of the first and second auxiliary pump bodies 51. , 52 fluidly connected to the suction side of the first auxiliary pump body 51, one end of the suction line 611 fluidly connected to the discharge side of the first auxiliary pump body 51, and one end of the second auxiliary pump body. And a second discharge line 612 fluidly connected to the discharge side.
Reference numeral 50 in FIG. 4 is a main pump for hydraulically operating various posture controls and the like of the work machine, and the first and second auxiliary pump bodies 51 and 52 share an oil source. In FIG. 4, a hydraulic circuit for various posture control of the work machine is omitted.

Further, the working vehicle 1 performs operation control of the power steering hydraulic circuit 60 to which pressure oil is supplied from the first auxiliary pump main body 51 via the first discharge line 611 and the various hydraulic units. Pressure oil is supplied from the second auxiliary pump body 52 through the second discharge line 612, the hydraulic circuit for the hydraulic unit 65, the HST hydraulic circuit 66 including the charge line 705 for supplying hydraulic oil to the HST 110, and the second discharge line 612. And a PTO hydraulic circuit 70 and a PTO hydraulic clutch 75 that control hydraulic oil supply and discharge for a work machine provided in the work vehicle 1, and a sub-transmission valve 80 that controls hydraulic oil supply and discharge control for the sub-transmission device 200. I have.
In this embodiment, the auxiliary transmission valve 80 is fluidly connected to an auxiliary transmission / discharge line 660 that is fluidly connected to the second discharge line 612.
The PTO hydraulic circuit 70 is fluidly connected to a 2WD / 4WD switching valve 90 for switching whether or not the driving force is transmitted to the auxiliary driving wheels of the work vehicle 1, and the power steering hydraulic circuit. A travel system brake unit 95 that can brake the drive wheels is fluidly connected to 60.

  Excess oil for the PTO hydraulic circuit 70 and return oil from the PTO hydraulic circuit 70 are supplied to the hydraulic unit hydraulic circuit 65, and the power steering hydraulic circuit 60 is supplied to the HST hydraulic circuit 66. Excess oil and return oil from the power steering hydraulic circuit 60 are supplied.

The HST hydraulic circuit 66 includes a supply line 620 fluidly connected to a hydraulic power source, a pair of HST hydraulic fluid paths 701 that fluidly connect the hydraulic pump main body 112 and the hydraulic motor main body 114, and the pair of HST hydraulic fluids. The passage 701 has the charge line 705 for supplying hydraulic oil.
In addition, the control shaft of the output adjusting member 115 that tilts the hydraulic pump main body 112 in the HST 110 is rotated around the axis by a hydraulic servo mechanism 125 that is operated in accordance with the operation of an operation member such as a shift lever. It has become.
In this embodiment, the hydraulic servomechanism 125 includes an output adjustment member hydraulic actuator 119 for operating the output adjustment member 115 and a hydraulic servo valve 120 that switches between supply and discharge of hydraulic oil to and from the output adjustment member hydraulic actuator 119. And a servo hydraulic actuator (hydraulic cylinder and hydraulic piston) 121 for operating the hydraulic servo valve 120, and an electromagnetic proportional valve 122 for switching supply and discharge of hydraulic fluid to and from the servo hydraulic actuator 121.
When the electromagnetic proportional valve 122 is electrically switched in response to a manual operation of a main speed change operation member, which will be described later, hydraulic oil from the supply line 620 is supplied to the hydraulic actuator 121, and the hydraulic actuator 121 moves. When the hydraulic servo mechanism 120 is switched according to the movement of the hydraulic actuator 121, the hydraulic servo mechanism 120 is separately supplied from the supply line 620 using hydraulic oil from the electromagnetic proportional valve 122 as a trigger. Is supplied to the output adjusting member 115 to tilt the movable swash plate.
Note that reference numeral 605 in FIG. 4 is a check valve that allows inflow of hydraulic oil from the charge line 705 to the corresponding HST hydraulic oil passage 701 and prevents reverse flow. This is a high pressure relief valve for preventing the HST hydraulic fluid passage 701 from becoming an abnormally high pressure.

As shown in FIG. 4, the hydraulic circuit for hydraulic unit 65 includes a traveling system supply / discharge line 630 (630H, 630L, 630R) through which hydraulic oil is supplied to and discharged from the traveling system hydraulic switching unit 300, and the traveling system. A traveling system supply line 631 (631H, 631L, 631R) that supplies hydraulic oil toward the hydraulic switching unit 300 and an operation that is discharged from the traveling system hydraulic switching unit 300 through the traveling system supply / discharge line 630. A traveling system drain line 635 for draining oil to the oil sump and a traveling system switching valve 640 (640H, 640L, 640R) for controlling supply / discharge of the traveling system supply / discharge line 630 are provided.
The PTO hydraulic circuit 70 includes a PTO supply / discharge line 645 through which hydraulic oil is supplied to and discharged from the PTO hydraulic clutch 75, and hydraulic oil discharged from the PTO hydraulic clutch 75 through the PTO supply / discharge line 645. Is provided with a PTO drain line 650 for draining the oil into an oil sump, and a PTO switching valve 655 for controlling supply / discharge of the PTO supply / discharge line 645.
In the present embodiment, the traveling system supply line 631 is fluidly connected to the auxiliary transmission supply / discharge line 660 via a clutch valve 85, and the operation from the second discharge line 612 is performed through the auxiliary transmission supply / discharge line 660. Oil is supplied and discharged.

In the present embodiment, as described above, the traveling system hydraulic switching unit 300 includes the forward side high speed clutch 315H, the forward side low speed clutch 315L, and the reverse side clutch 315R, and performs two-stage switching during forward travel. At the same time, forward and backward switching can be performed.
Accordingly, the traveling system supply line 631 includes a forward-side high-speed supply line 631H, a forward-side low-speed supply line 631L, and a reverse-side supply line 631R, and the traveling system supply / discharge line 630 includes a high-speed-side forward supply / discharge line 630H, The travel system switching valve 640 includes a forward-side high-speed switching valve 640H that controls supply / discharge of the forward-side high-speed supply / discharge line 630H, and the forward-side low-speed supply. A forward-side low-speed switching valve 640L that controls the supply / discharge control of the exhaust line 630L and a reverse-side switching valve 640R that controls the supply / exhaust control of the reverse-side supply / discharge line 630R are included.

Further, in this embodiment, the hydraulic unit hydraulic circuit 65 includes a traveling system lubricating oil line 730 for supplying lubricating oil to the traveling system hydraulic switching unit 300.
The PTO hydraulic circuit 70 includes a PTO-based lubricating oil line 735 for supplying lubricating oil to the PTO hydraulic clutch 75. The traveling system lubricant line 730 and the PTO system lubricant line 735 are fluidly connected.

  When the travel system hydraulic switching unit 300 is positioned at the shut-off position where each of the switching valves 640H, 640L, 640R fluidly connects the corresponding travel system supply / discharge lines 630 to the drain lines 635, No hydraulic oil is supplied to any of the forward side high speed clutch 315H, the forward side low speed clutch 315L, and the reverse side clutch 315R, and the power is cut off.

  On the other hand, the forward side high speed switching valve 640H is positioned at a communication position where the forward side high speed supply / discharge line 630H is fluidly connected to the forward side high speed supply line 661 (in this case, the forward side low speed switching valve 640L And the reverse-side switching valve 640R are both located at the shut-off position), and when the clutch valve 85 is located at a communication position where hydraulic fluid can be supplied, the second discharge line 612 passes through the auxiliary transmission / discharge line 660. The supplied pressure oil is supplied to the forward-side high-speed clutch 315H via the forward-side high-speed supply / discharge line 630H, whereby the traveling system hydraulic switching unit 300 enters the forward-side high-speed transmission state.

Similarly, the forward side low speed switching valve 640L is positioned at a communication position where the forward side low speed supply / discharge line 630L is fluidly connected to the forward side low speed supply line 631L (in this case, the forward side high speed switching valve 640H and When the reverse valve 640R is positioned at the shut-off position) and the clutch valve 85 is positioned at a communication position where hydraulic oil can be supplied, the second discharge line 612 is supplied through the auxiliary transmission / discharge line 660. The pressurized oil is supplied to the forward-side low-speed clutch 315L via the forward-side low-speed supply / discharge line 630L, whereby the traveling system hydraulic switching unit 300 enters the forward-side low-speed transmission state.
In order to prevent a so-called shift shock that occurs when the power is temporarily cut off and reconnected when switching between the forward high speed transmission state and the forward low speed transmission state, the forward high speed Both the clutch 315H and the forward-side low-speed clutch 315L can be provided with a state in which pressure oil flows (clutch double-engaged state), whereby the forward-side high-speed transmission state, the forward-side low-speed transmission state, and the forward-side low-speed transmission state It is possible to smoothly switch from the state to the forward side high-speed transmission state.

  Further, the reverse side switching valve 640R is located at a communication position where the reverse side supply / discharge line 630R is fluidly connected to the reverse side supply line 631R (at this time, the forward side high speed switching valve 640H and the forward side low speed When the clutch valve 85 is positioned at a communication position where hydraulic fluid can be supplied, the pressure supplied from the second discharge line 612 through the auxiliary transmission / discharge line 660 is determined. Oil is supplied to the reverse clutch 315R via the reverse supply / discharge line 630R, whereby the travel system hydraulic switching unit 300 enters the reverse transmission state.

The auxiliary transmission device 200 includes an auxiliary transmission actuator 81 that moves the shifter 209 in the axial direction of the propeller shaft 206 (vehicle longitudinal direction).
Specifically, the auxiliary transmission actuator 81 has a cylinder mechanism to which hydraulic fluid is supplied from the auxiliary transmission / discharge line 660 via the auxiliary transmission valve 80.
That is, the auxiliary transmission valve 80 moves the shifter 209 to one side of the propeller shaft 206 in the front-rear direction of the propeller shaft 206 (here, the front side) via the auxiliary transmission actuator 81, thereby moving the propeller shaft 206 to the high speed side. By moving the shifter 209 to the other side of the propeller shaft 206 in the longitudinal direction of the propeller shaft 206 (rear side in this case) via the auxiliary transmission actuator 81, the propeller shaft 206 A low-speed position where the concave-convex coupling with the low-speed driven gear 208 is selectively made possible.
Note that the position of the auxiliary transmission valve 80 is controlled by, for example, electrically detecting the operation position of an auxiliary transmission operation member that can be manually operated.
In the present embodiment, the auxiliary transmission valve 80 is a two-position valve that can selectively take either the high speed position or the low speed position of the shifter 209. In addition to the high speed position and the low speed position, the shift valve 209 is connected to the high speed side driven gear 207 and the low speed side driven gear 208 so that the shift valve 209 does not engage with the concave and convex portions. It is also possible to configure such that a blocking position positioned between the high speed stage position and the low speed stage position can be selectively taken.

Subsequently, the shift control of the HST 110 and the auxiliary transmission 200 will be described.
First, the maximum speed setting control for each gear position in the auxiliary transmission 200 will be described.
FIG. 5 shows a schematic configuration diagram relating to the control system of the working vehicle 1 of FIG.
As shown in FIG. 5, the working vehicle 1 according to the present embodiment is a main speed change operation member (for example, a main speed change lever) 810 for changing the speed of the HST 110 that is a main speed change device, and can be operated in a predetermined manner. A main transmission operation member 810 that can be manually operated over a range, a main transmission operation detection sensor 820 that detects an operation position of the main transmission operation member 810, and a movable swash plate of the output adjustment member 115 of the HST 110 are tilted. A main transmission actuator 830 (in the present embodiment, the hydraulic servo mechanism 125) to be rotated, a sub transmission operation member 840 for operating the sub transmission 200 to perform a shift operation, and an operation of the sub transmission operation member 840 A sub-shift detection for detecting a shift stage in which the sub-transmission actuator 81 for shifting the sub-transmission device 200 and the sub-transmission device 200 are engaged. A control device 800 that controls the operation of the main transmission actuator 830 based on a signal from the sensor 850, a signal from the main transmission detection sensor 820, and the main transmission operation member 810 when the maximum operation is performed within the operable range. And a maximum speed setting mechanism 870 for changing the gear ratio of the HST 110.
In the present embodiment, the operation of the auxiliary transmission operation member 840 is transmitted to the control device 800 via an auxiliary transmission operation detection sensor 890 described later.

According to the work vehicle 1 configured as described above, when the maximum speed setting mechanism 870 changes the speed ratio of the HST 110 when the main speed change operation member 810 is operated to the maximum within a predetermined operable range, the control device 800 controls the main transmission actuator 830 based on the changed gear ratio to operate the output adjustment member 115 of the HST 110 (tilt the movable swash plate).
That is, even when the main speed change operation member 810 is operated to the maximum, the control device 800 controls the output rotation speed of the HST 110 so that the predetermined speed set by the maximum speed setting member 870 is obtained.

The working vehicle 1 according to the present embodiment is configured to be able to set and store the maximum speed for each gear position of the auxiliary transmission 200 by a single maximum speed setting member 871.
That is, the maximum speed setting mechanism 870 includes a single maximum speed setting member 871 that can be manually operated, and a maximum speed setting sensor 872 that detects an operation amount of the maximum speed setting member 871.
Then, the control device 800 sets the highest speed value based on the operation amount of the highest speed setting member 871 in a state where the auxiliary transmission device 200 is engaged with any one of the shift speeds. The maximum speed setting value can be stored.

Specifically, when the sub-transmission device 200 is engaged with any one of the gear positions (for example, the high speed gear), the control device 800 is based on the detection signal from the sub-transmission detection sensor 850. The engagement stage of the auxiliary transmission 200 is recognized. In this state, when the highest speed setting member 871 of the highest speed setting mechanism 870 is manually operated, the highest speed setting sensor 872 detects the operation amount of the highest speed setting member 871, and the control device 800 determines the operation amount. The maximum speed value based on this is stored in the storage area (EEPROM in FIG. 5) 805 that is not lost even when the power is turned off as the maximum speed setting value of the one gear.
When the sub-transmission device 200 is shifted from the first gear to another gear (for example, a low-speed gear), the controller 800 detects the sub gear based on a detection signal from the sub gear detection sensor 850. It is recognized that the transmission 200 is engaged with another engagement stage. In this state, when the highest speed setting member 871 of the highest speed setting mechanism 870 is artificially operated, the highest speed setting sensor 872 detects the operation amount of the highest speed setting member 871, and the control device 800 The maximum speed value based on the amount is stored in the storage area (EEPROM in FIG. 5) 805 which is not lost even when the power is turned off as the maximum speed setting value of the other gear.

  As described above, the maximum speed can be set and stored for each shift stage of the auxiliary transmission 200, so that the maximum speed setting mechanism 870 must be operated every time the auxiliary transmission 200 is changed. Inconvenience that it should not be avoided can be prevented, and the operability of the work vehicle 1 can be improved.

That is, in the conventional work vehicle, a sensor for detecting the operation position of the highest speed setting member such as a potentiometer is used as the highest speed setting sensor, and the highest speed setting member is used regardless of the shift speed of the auxiliary transmission. The maximum speed is set according to the operation position.
Therefore, in such a conventional work vehicle, for example, when the desired maximum speed is set by the maximum speed setting member in a state where the auxiliary transmission is engaged in the low speed stage during work traveling in one field, When the sub-transmission device is engaged with the high speed stage when moving from the one field to another field after the work is completed, the maximum speed determined by the operating position of the maximum speed setting member is the high speed stage engagement of the sub-transmission apparatus. This is sometimes applied, resulting in a disadvantage that the desired speed cannot be obtained quickly.
Of course, when the auxiliary transmission is engaged with the high speed stage, the maximum speed setting member can be changed to the maximum position (for example, 100). At the start of the operation, it is necessary to reset the maximum speed setting member to the predetermined maximum speed again, which is complicated.

On the other hand, in the present embodiment, as described above, the maximum speed setting sensor 872 is configured to detect the operation amount of the maximum speed setting member 871, and the sub-transmission device 200 has one gear position. The control device 800 is configured to store the operation amount of the maximum speed setting member 871 in the state of being engaged with the maximum speed of the one gear position.
Therefore, even if the maximum speed setting value in one gear stage is changed, the maximum speed setting value in the other gear stage is not affected. Even in such a case, the vehicle can travel at an appropriate maximum speed according to the gear position.

In the present embodiment, the maximum speed setting member 871 can be rotated in both directions around the operation axis.
The maximum speed setting sensor 872 is a rotary encoder that outputs first and second pulse trains P1 and P2 having the same waveform and different phases according to the operation amount of the maximum speed setting member 871 around the operation axis 874. 873.
The control device 800 detects the operation amount by detecting the number of pulses output from the rotary encoder 873 according to the rotation amount of the maximum speed setting member 871 around the operation shaft 874, and detects the operation amount. When the output of the pulse train P1 changes to ON, the operation direction is detected by detecting whether the output of the second pulse train P2 is ON or OFF.
In the detection of the manipulated variable, the number of pulses in one of the first and second pulse trains P1 and P2 may be counted, but one of the outputs of the first and second pulse trains P1 and P2 is counted. When the other output value does not change after the output value changes, it is preferable not to detect the operation amount. As a result, it is possible to effectively prevent the maximum speed setting value from being updated unexpectedly at the time of a failure in which the output line is disconnected or short-circuited.

  FIG. 6 shows a rotary encoder output diagram of the highest speed setting sensor in this embodiment. 6A shows an encoder output when the highest speed setting member 871 is rotated to one side (clockwise) around the operation shaft 874, and FIG. 6B shows the operation of the highest speed setting member 871. The encoder output when rotating around the shaft 874 to the other side (counterclockwise) is shown.

In this case, when the highest speed setting member 871 is rotated around one of the operating shafts 874, as shown in FIG. The second pulse trains P 1 and P 2 are output from the rotary encoder 873 and input to the control device 800.
By detecting the number of pulses output from the rotary encoder 873 among the outputs of the rotary encoder 873 input to the control device 800, the operation amount of the highest speed setting member 871 is detected. Of the outputs of the rotary encoder 873 input to the control device 800, the output state of the second pulse train P2 when the output of the first pulse train P1 output from the rotary encoder 873 changes to ON (time Ton) is By detecting whether it is ON or OFF, the operation direction of the highest speed setting member 871 is detected.
That is, since the first pulse train P1 and the second pulse train P2 output from the rotary encoder 873 have the same waveform and different phases, in this embodiment, the rotary encoder 873 is operated clockwise around the operation axis 874. When the output of the first pulse train P1 is changed to ON, the output of the second pulse train P2 is turned off (FIG. 6A), and when the operation is performed counterclockwise around the operation axis 874, the output of the first pulse train P1 is The output of the second pulse train P2 when turned on is turned on (FIG. 6 (b)).

As described above, by employing the rotary encoder 873 having the above-described configuration as the maximum speed setting sensor 872, the operation amount and the operation direction by the maximum speed setting sensor 872 can be reliably detected.
By configuring the rotary encoder 873 so that the number of pulses to be output changes according to the operation speed (rotation speed) (even if the operation amount is the same, the higher the rotation speed, the more pulses are output). Regardless of the maximum speed setting change amount, it is possible to easily update the maximum speed setting value in a short time.

Here, the maximum speed setting member operation amount detection process in the maximum speed setting control in the present embodiment will be described in detail.
FIG. 7 shows a flowchart regarding the maximum speed setting member operation amount detection process in the maximum speed setting control in the present embodiment.
First, when the highest speed setting member 871 is operated, the control device 800 detects the first start pulse among the output pulses of the first and second pulse trains P1 and P2 output by the rotary encoder 873 ( Step S11). Using the detection of the start pulse as a trigger, the control device 800 activates the built-in timer 806 to start measuring time (step S12). That is, time T = 0 when the start pulse is detected.

FIG. 8 shows a schematic diagram of a display 880 provided in the work vehicle 1 in the present embodiment.
The control device 800 causes the display 880 provided in the work vehicle 1 to display the maximum speed setting value at the gear stage currently engaged in the auxiliary transmission device 200 based on the human operation signal. it can. By providing such a configuration, operability can be improved.
The display mode of the display unit 880 is not particularly limited. For example, the maximum speed setting value is displayed using a number or a level gauge on the liquid crystal display unit 881 provided in the display unit 880. In the vehicle speed display portion 882 of the display unit 880, a portion corresponding to the maximum set value can be lit or displayed in another color.

  In the present embodiment, the control device 800 detects the start shift output from the rotary encoder 873 as a trigger and detects the shift currently engaged with the sub-transmission device 200 detected by the sub-shift detection sensor 850. The highest speed set value currently stored in the stage is displayed on the display 880.

  In this way, by using the start pulse at the time of operating the maximum speed setting member 871 as a display trigger signal to the display unit 880, it is currently engaged without separately providing an operating tool for confirming the maximum speed. It is possible to easily confirm the maximum speed setting value at the shift stage of the auxiliary transmission 200.

More preferably, the control device 800 can be configured not to count the start pulse as a signal for setting the maximum speed. It is possible to effectively prevent the change.
Specifically, in the present embodiment, the control device 800 is within a predetermined time Td from the first start pulse (time T0) among the output pulses of the first and second pulse trains P1 and P2 output by the rotary encoder 873. The output pulses detected in the above are not counted as manipulated variables.
That is, the control device 800 detects the number of pulses of the detected pulse train as a signal for changing the maximum speed after the predetermined time Td (for example, 100 ms) has elapsed since the start pulse is detected (T = 0). (Steps S13 and S15). At this time, the timer is reset after a predetermined time Td has elapsed (step S14).

In this case, an output pulse detected within a predetermined time Td after the first start pulse of the output pulses of the first and second pulse trains P1 and P2 output by the rotary encoder 873 is detected at time T = 0 (see FIG. 6 is not counted as an operation amount by the control device 800, but is ignored.
Thereby, it is possible to prevent the maximum speed setting value from being changed against the operator's intention when the maximum speed setting member 871 is touched by mistake. In addition, when the highest speed setting member 871 is operated only to confirm the current highest speed setting value as described above, it is possible to prevent the highest speed setting value from changing.

  Further, in the present embodiment, the control device 800 is in a first output state where the output of the second pulse train P2 outputs either ON or OFF when the output of the first pulse train P1 changes to ON. When the output of the first pulse train P1 changes to ON within the first predetermined time T1, the output of the second pulse train P2 changes to the second output state that outputs either ON or OFF ( No in step S15 and Yes in step S18) is configured not to count the output pulse detected within the second predetermined time T2 from when the state is changed to the second output state as an operation amount.

In the present embodiment, when the output of the first pulse train P1 changes from ON to OFF, the timer 806 is activated (step S16), and if the next pulse is not detected before the time passes T1, It is recognized that the operation of the maximum speed setting member 871 has been completed at that time.
When the next pulse is detected before the time T1 elapses, the output of the second pulse train P2 when the output of the next pulse changes to ON is the output state up to the previous pulse (first If it is the same as the one output state), the control device 800 counts the pulse as the maximum speed setting member 871 operation amount.
On the other hand, the output of the second pulse train P2 when the output of the next pulse changes to ON becomes an output state (second output state) different from the output state (first output state) up to the previous pulse. (No in step S17 and Yes in step S20), the timer 806 is measured again (step S21), and the pulse amount of the second output state is not detected until the time passes the second predetermined time T2 ( Steps S22 and S24) are controlled. Therefore, the operation amount is detected from the pulse output for the reverse rotation input exceeding the second predetermined time T2 (step S24). At this time, after the second predetermined time T2 has elapsed, the timer is reset (step S23), and after the second output state is detected, timer measurement is started again (step S25).

In this manner, after the first output state is detected by operating the highest speed setting member 871 clockwise or counterclockwise around the operation shaft 874, the highest speed is set within the first predetermined time T1. When the second output state is detected by operating the setting member 871 clockwise or counterclockwise around the operation shaft 874, the second output state is detected within a second predetermined time T2. The detected output pulse is not counted as an operation amount by the control device 800 and is ignored.
As a result, when the maximum speed setting member 871 is rotated to any one side around the operation shaft 874 and stopped at a desired position, the operator inputs a minute time reverse rotation operation unexpectedly. Even so, since the reverse rotation operation is invalidated, the desired operation amount can be input more reliably and more easily.

  In the present embodiment, the control device 800 is in a state where a predetermined time T3 has elapsed after the operation of the highest speed setting member 871 in a state where the auxiliary transmission device 200 is engaged with any one of the gear positions, or When the sub-transmission device is engaged with another gear position within the predetermined time T3 (Yes in step S18), the highest speed value based on the operation amount of the highest speed setting member 871 is set to the first gear speed. It is stored in the storage area (EEPROM) 805 that is not lost even when the power is turned off as the maximum setting value of the stage (step S19).

  In this case, after the maximum speed setting member 871 is operated in a state where the auxiliary transmission device 200 is engaged with any one of the gear positions, the timer 806 starts measurement in step S16 or step S25, and then the predetermined time T3. Or the maximum speed value based on the operation amount of the maximum speed setting member 871 is the maximum speed of the one shift stage only after the auxiliary transmission 200 is engaged with another shift stage within the predetermined time T3. The set value is stored in the EEPROM 805 by the control device 800.

  This eliminates the need for the operator to perform a separate operation when storing the maximum speed set value, and prevents the user from forgetting to perform the storage operation. Further, if the maximum speed setting member 871 is stored immediately after the operation, the operation amount of the maximum speed setting member 871 needs to be stored again many times when the operation amount of the maximum speed setting member 871 is finely adjusted. As a result, a problem that the processing speed decreases may occur, but such a problem can be prevented in advance by storing after waiting for the predetermined time T3 or the change of the gear position of the auxiliary transmission 200. At the same time, when the EEPROM 805 with a limited number of times of writing is used, the number of times of writing can be reduced, so that the lifetime of the EEPROM 805 can be extended.

  In addition, in step S19, the control device 800 has a maximum speed value based on an operation amount of the maximum speed setting member 871 in a state where the auxiliary transmission device 200 is engaged with any one of the shift speeds. If it is the same as the maximum speed setting value 871 before the operation, the storage in the EEPROM 805 is not updated.

In this case, when the highest speed value based on the operation amount of the highest speed setting member 871 is stored in the EEPROM 805, if the highest speed value is the same as the highest speed setting value before the operation, the storage area by the control device 800 is stored. No memory update is performed.
As a result, when the EEPROM 805 with a limited number of times of writing is used, useless writing is eliminated, and the number of times of writing is reduced, so that the life of the storage area can be extended.

  In the present embodiment, the configuration in which the maximum speed setting sensor 872 includes the rotary encoder 873 has been described, but instead of this, the maximum speed setting sensor 872 is set to the maximum speed for each shift stage of the auxiliary transmission 200 (two in the present embodiment). It may be configured to include a maximum speed setting member 871 such as a high speed setting dial and a maximum speed setting sensor 872 having a potentiometer.

Further, the highest speed setting member 871 is an electric switch (tact switch) in which the ON / OFF state of the switch is electrically stored, and the highest speed setting sensor 872 detects the operation time (energization time) of the electric switch. It may be configured as an operation time detection sensor.
In this case, when the sub-transmission device 200 is engaged with one shift stage, the time during which the electric switch is held in the ON state (for example, a push button type electric switch is kept pressed) The maximum speed value to be input changes according to the time), and the control device 800 is input by turning the electric switch to the OFF state (in the case of the push button type, the hand is released). The maximum speed value is stored as the maximum speed setting value at the one gear position. By performing this for each gear position, the maximum speed for each gear position of the auxiliary transmission 200 can be stored.

Further, by using the single maximum speed setting member 871 and the single potentiometer (maximum speed setting sensor 872), the control device 800 includes the following configuration, so that the maximum speed for each gear position of the auxiliary transmission 200 is also provided. Can be stored.
That is, the control device 800 1) sets the maximum speed setting value for the one gear position based on the position signal from the potentiometer in a state where the sub-transmission device 200 is engaged with any one gear position. 2) When the maximum speed setting member 871 is operated in a state in which the auxiliary transmission device 200 is engaged with the one speed stage after storing the maximum speed setting value for the one speed stage. May be configured not to update the maximum speed setting value unless the maximum speed setting member 871 is operated to the operation position corresponding to the stored maximum speed setting value.
In this case, when the maximum speed setting member 871 is operated in a state where the update of the maximum speed setting is not permitted, it is preferable to display the fact on the display 880 or the like.

Next, the initial adjustment mode of the HST 110 in the working vehicle 1 will be described.
In the present embodiment, the working vehicle 1 further includes a vehicle speed sensor 860 that directly or indirectly detects the rotational speed of the drive wheel 30, as shown in FIG.

Then, the control device 800 inputs a target rotational speed (target vehicle speed) of the drive wheels 30 corresponding to the operation amount of the main transmission operation member 810 from the main transmission operation detection sensor 820, and based on the input signal, the main transmission operation detection sensor 820 inputs the main rotation speed. In addition to the normal control mode for controlling the operation of the speed change actuator 830, an initial adjustment mode for adjusting the relationship between the output of the HST 110 and the operation amount of the main speed change operation member 810 is provided.
For mode switching between the normal control mode and the initial adjustment mode, for example, input is performed interactively using the display unit 880, or a mode transition is performed such as starting the drive source 10 while pressing a predetermined operation switch. This is done by performing an operation.

In the initial adjustment mode, when the working vehicle 1 is actually run, a control function indicating the relationship between the output (vehicle speed) of the HST 110 and the operation control amount of the main transmission actuator 830 is calculated.
Specifically, first, based on the vehicle speed sensor 860, the main transmission actuator 830 is operated so that the rotational speed of the drive wheel 30 becomes a predetermined first speed V1, and the HST motor shaft rotational speed at that time is The EEPROM 806 stores the movable swash plate inclination angle R1 and the operation control amount (current value applied to the electromagnetic proportional valve 122) S1 of the HST 110.
Next, based on the vehicle speed sensor 860, the rotational speed of the drive wheel 30 is a predetermined second speed V2, which is different from the first speed V1, specifically zero, that is, the working vehicle 1 is stopped. The main transmission actuator 830 is operated, and the EEPROM 806 stores the movable swash plate inclination angle R2 of the HST 110 and the operation control amount (applied current value to the electromagnetic proportional valve 122) S2 at the HST motor shaft rotation speed at that time.
Linear interpolation is performed based on the first and second operation control amounts S1 and S2 obtained in this manner, and the rotational speed change (vehicle speed change) of the drive wheels 30 with respect to the operation control amount of the main transmission actuator 830. Is calculated and stored in the EEPROM 806.
FIG. 9 shows a graph of the control function of the HST 110 calculated in the initial adjustment mode.
In FIG. 9, the movable swash plate inclination angle (the operation control amount of the main transmission actuator 830) of the HST 110, which is the vertical axis, is displayed as a non-dimensional value (1000 steps in the forward or reverse direction).

  In the normal control mode, the operation of the main transmission actuator 830 corresponding to the target rotational speed input by the main transmission operation detection sensor 820 using the control function stored in the EEPROM 805 in the initial adjustment mode. A control amount is calculated, and operation control of the main transmission actuator 830 is performed based on the calculated operation control amount. That is, feedforward control is performed.

  For example, when the target rotational speed corresponding to the operation amount of the main transmission operation member 810 detected by the main transmission operation detection sensor 820 based on the operation of the main transmission operation member 810 by the operator is input, the control device 800 An operation control amount that achieves the target rotational speed is calculated using a control function, and the main transmission actuator 830 is controlled to operate by the operation control amount.

As described above, the relationship between the operation control amount of the main transmission actuator 830 set using the initial adjustment mode and the actual rotation speed of the drive wheel 30 is held in advance as a control function, so that the main transmission operation can be performed with a simple structure. It is possible to control the operation of the main transmission actuator 830 so that there is no difference between the target rotational speed of the drive wheel 30 corresponding to the operation amount of the member 810 and the actual rotational speed of the drive wheel 30.
Accordingly, the actual vehicle speed of the work vehicle 1 is the predetermined speed at which the main speed change operation member 810 is positioned even though the control device 800 positions the output adjustment member 115 at the predetermined position via the main speed change actuator 830. Thus, it is possible to prevent a situation where the speed does not reach the speed position corresponding to the speed position, and to easily obtain the vehicle speed corresponding to the operation position of the main transmission operation member 115 regardless of the manufacturing error of the HST 110.
In the present embodiment, the control current values at the first and second speeds V1 and V2 are detected. However, the control current values at more speed points are detected, and the distance between two adjacent points is linear. It may be supplemented. This is particularly effective in specifications where the output characteristics of the HST 110 are quadratic curves.

  In addition, the control function is calculated by using an actual measurement value for the operation control amount of the main transmission actuator 830 when the work vehicle 1 is stopped, thereby obtaining a main shift for obtaining the stop state of the work vehicle 1 in the normal control mode. The error in the operation control amount of the actuator 830 can be reduced to zero or as much as possible.

In particular, in the present embodiment, as described above, the working vehicle 1 includes an HMT in which the HST 110 and the planetary gear unit 150 are combined in the traveling system transmission path, and further, the output adjusting member 115. When the vehicle is positioned at a position other than the neutral position, the vehicle speed becomes zero.
In such a working vehicle 1, if the operation control amount of the main transmission actuator 830 when the working vehicle 1 is stopped is not accurately determined, the main transmission operation member 810 is positioned at the vehicle stop position. Regardless, there arises a disadvantage that the working vehicle 1 moves forward or backward.
Therefore, it is particularly effective in the working vehicle 1 to calculate the control function using the actual measurement value for the operation control amount of the main transmission actuator 830 when the working vehicle 1 is stopped.

  In the normal control mode, the control device 800 according to the present embodiment detects the target rotational speed and the vehicle speed sensor 860 when the main transmission actuator 830 is controlled to operate based on the control function. A difference from the rotational speed of the drive wheel 30 is calculated, and the main transmission actuator 830 is feedback-controlled so that the difference is eliminated.

  In other words, in the normal control mode, the control device 800, in addition to the feedforward control of the main transmission actuator 830 based on the control function, the target rotational speed corresponding to the operation amount of the main transmission operation member 810 and the actual driving wheel 30. The main speed change actuator 830 performs feedback control by the control device 800 in a direction in which the rotational speed (vehicle speed) of the control device 800 matches.

Thus, by performing the feedback control, the desired vehicle speed (target rotational speed) and the actual vehicle speed can be made to coincide with each other with high accuracy, and more optimal output control for the main transmission actuator 830 can be performed.
Further, by performing the feedback control after performing the feedforward control, it is possible to perform the control to the appropriate value more quickly than the case where only the feedback control is performed.

Next, the control structure during the switching operation in the auxiliary transmission 200 will be described.
In the present embodiment, the working vehicle 1 is configured to detect whether or not the switching operation of the auxiliary transmission 200 is abnormal and to perform the following control when abnormal.
FIG. 10 is a partial cross-sectional view of the auxiliary transmission device 200 and the auxiliary transmission actuator 81 in the working vehicle 1 of the present embodiment.
In the present embodiment, the working vehicle 1 has a sub-speed change operation mechanism that moves the shifter 209 in the axial direction in accordance with the operation of the sub-speed change actuator 81.
Specifically, as shown in FIG. 10, the auxiliary speed change operation mechanism includes a fork shaft 221 arranged in parallel to a shaft (in the present embodiment, the propeller shaft 206) on which the shifter 209 is supported, A shift fork 222 having an end fixed to the fork shaft 221 and a fork engaged with the shifter 209 at the tip is provided.

On the other hand, the sub-transmission actuator 81 is accommodated in a cylinder 81a to which hydraulic oil from the sub-transmission valve 80 (FIG. 4) is supplied and discharged, and is fluidly slidably accommodated in the cylinder 81a, and a tip portion thereof is A piston 81b extending outward from the cylinder 81a and connected to the fork shaft 221;
The base end portion of the piston 81b divides the internal space of the cylinder 81a into a low speed chamber and a high speed chamber.
The shifter 209 is moved as follows.
That is, by switching the hydraulic oil supply / discharge to / from the low speed chamber and the high speed chamber by the auxiliary transmission valve 80, the piston 81b moves forward and backward in the axial direction, and moves the fork shaft 221 forward and backward in the axial direction. With the axial movement of the fork shaft 221, the shifter 209 moves in the axial direction of the propeller shaft 206 via the shift fork 222 fixed to the fork shaft 221.
At this time, the shifter 209 is selectively positioned at the high speed stage position on one side in the axial direction and the low speed stage position on the other side in the axial direction across the position where the power is cut off.

Furthermore, the working vehicle 1 includes the auxiliary shift detection sensor 850 as described above.
The auxiliary transmission detection sensor 850 detects the operating state of the auxiliary transmission actuator 81 directly or indirectly.
In the present embodiment, the auxiliary transmission detecting sensor 850 is an axis line of an auxiliary transmission operation assembly including the piston 81b, the fork shaft 221, the shift fork 222, and the shifter 209 that integrally move forward and backward along the axial direction. By detecting the direction position, the operating state of the auxiliary transmission operating mechanism (that is, the engagement stage of the auxiliary transmission 200) is detected.
Specifically, as shown in FIG. 10, the auxiliary transmission detection sensor 850 includes a detection shaft 851 arranged so as to be rotatable about an axis in a state substantially orthogonal to the fork shaft 221, and the auxiliary transmission assembly ( In this embodiment, it is an engagement piece 852 provided on the shift fork 222), and the detection shaft 851 is rotated so that the detection shaft 852 rotates around the axis in accordance with the axial movement of the auxiliary transmission assembly. And an engagement piece 852 coupled to the detection shaft 851 so as to rotate around the axis.

Further, as described above, the work vehicle 1 has the auxiliary transmission operation detection sensor 890 that detects the operation position of the auxiliary transmission operation member 840.
The control device 800 controls the operation of the auxiliary transmission actuator 81 based on a signal from the auxiliary transmission operation detection sensor 890.
The auxiliary transmission operation detection sensor 890 is a position detection sensor such as a contact switch that detects an operation position of the auxiliary transmission operation member 840, or an operation amount detection such as a potentiometer that detects an operation amount of the auxiliary transmission operation member 840. It is assumed to be a sensor.

FIG. 11 shows a flowchart relating to the switching abnormality process in the auxiliary transmission actuator control in the present embodiment.
In a state in which the auxiliary transmission operation member 840 is positioned at one of the high speed position and the low speed position, the auxiliary transmission actuator 81 is controlled by the control device 800 to an operating state corresponding to the one speed position. Has been.
When the auxiliary transmission operation member 840 is operated from this state to the other one of the high speed position and the low speed position, the control device 800 causes the auxiliary transmission operation detection sensor 890 to detect the high speed position or the low speed stage of the auxiliary transmission operation member 840. A signal corresponding to an operation from one of the positions to the other is received (step S21), and the auxiliary transmission device 200 corresponds to the other gear position from one gear position corresponding to the one gear position. Operation control of the auxiliary transmission actuator 81 is performed so as to shift to the other gear stage state.
More specifically, the sub-shift actuator 81 moves the shifter 209 from the position corresponding to the one gear position (hereinafter referred to as the pre-shift position) via the sub-shift operation mechanism, through the power cutoff position, It operates to move to a position corresponding to the gear position (hereinafter referred to as post-shift position).

Note that when the auxiliary transmission operation member 840 is operated from the high speed position to the low speed position, the control device 800 determines the vehicle speed at the time of operation of the auxiliary transmission operation member 840 detected by the vehicle speed sensor 860. It is determined whether or not the sub-transmission device 200 is within a shiftable range in the low speed stage state (that is, whether or not the current vehicle speed is within a shiftable range from the high speed stage to the low speed stage of the subtransmission device 200). (Step S22). The reason for performing this process will be described later.
On the other hand, in the present embodiment, when the auxiliary transmission operating member 840 is operated from the low speed position to the high speed position, the control device 800 determines that the speed is always within the shiftable range in step S22. .

Then, only when the vehicle speed at the time of the operation is within the speed changeable range (Yes in step S22), the control device 800 determines that the sub transmission 200 is based on a signal from the sub transmission operation detection sensor 890. The auxiliary transmission actuator 81 is controlled to perform the corresponding speed change operation (step S23).
If the vehicle speed at the time of the operation is not within the shiftable range in the low speed stage state of the auxiliary transmission 200 (No in step S22), until the vehicle speed detected by the vehicle speed sensor 860 becomes a vehicle speed within the shiftable range, The operation control of the auxiliary transmission actuator 81 is not permitted (step S24).
Specifically, the output of the drive source 10 and / or the HST 110 is controlled to be decelerated regardless of whether or not the operator performs a decelerating operation.

The maximum vehicle speed in the low speed stage state is lower than the maximum vehicle speed in the high speed stage state due to the difference in the gear ratios of the respective speed stages in the sub transmission 200, so that the sub transmission 200 changes from the high speed stage state to the low speed stage. When shifting to the state, if the vehicle speed at the time of operation of the auxiliary speed change operation member 840 is equal to or higher than the maximum vehicle speed in the low speed state, that is, if the speed change operation is forcibly performed, the work vehicle 1 will There is a risk of sudden braking or damage to the traveling system transmission path.
Therefore, whether or not the vehicle speed at the time of operation of the auxiliary transmission operation member 840 from the high speed position to the low speed position is within a shiftable range to the low speed stage of the auxiliary transmission 200 (when the auxiliary transmission 200 is in the low speed state). Only in the shiftable range, the subtransmission device 200 is allowed to shift to the low speed stage state, thereby preventing the inconvenience. Yes.

After controlling the operation of the auxiliary transmission actuator 81, the control device 800 determines whether the transmission operation of the auxiliary transmission device 200 is successful based on a signal from the auxiliary transmission detection sensor 850 (step S25).
That is, in this step S25, the shift speed state of the auxiliary transmission device 200 detected from the auxiliary shift detection sensor 850 and the shift position of the auxiliary transmission operation member 840 detected from the auxiliary transmission operation detection sensor 890 are determined. It is determined whether they are consistent.

  When it is determined that the auxiliary transmission device 200 has failed to shift to the other gear position (No in step S25), the control device 800 displays a predetermined alarm (first alarm) on the display unit 880. Then, the operator is notified that the shifting operation in the auxiliary transmission 200 has failed (step S26).

  As a result, the operator can visually know that the shift to the other shift stage has failed, and therefore can quickly respond to a shift failure.

  Further, when it is determined that the auxiliary transmission device 200 has failed to shift to the other gear position (No in step S25), the control device 800, in addition to notifying the operator, The sub-transmission actuator 81 is controlled to operate so that the transmission 200 returns to the shift state before the sub-transmission operation member 840 is operated (step S27).

  According to the above control, the sub-transmission device 81 is operated regardless of whether the sub-transmission actuator 81 is operated in accordance with an operation from one of the high speed position and the low speed position of the sub transmission operation member 840 to the other. It is possible to effectively prevent the inconvenience that 200 is kept in the power cut-off state.

This will be described in detail.
When the sub-shift actuator 81 moves the shifter 209 from the pre-shift position to the post-shift position through the power shut-off position, the gear ratio is changed by shifting the engaged shift speed from one to the other, There is a difference in the rotational speed (vehicle speed) of the output shaft (propeller shaft 206) before and after shifting.
That is, the difference between the vehicle speed (output shaft speed) in the power shut-off state and the vehicle speed in the one gear position (position before shifting) is the difference between the vehicle speed in the power shut-off state and the other gear position (post-shift position). It will be larger than the difference from the vehicle speed.

For this reason, the sub-transmission device 200 is operated in spite of the operation of the sub-transmission actuator 81 from the one gear position to the other gear position of the sub-shift operation member 840 according to the operation. However, although one shift stage state has shifted to the power cut-off state, it is possible that the power cut-off state does not shift from the power cut-off state to the other shift stage state, and the power cut-off state continues unintentionally.
When such a power shut-off state occurs against the intention, the sub-transmission device 200 was engaged most recently rather than continuing the operation control for shifting the sub-transmission device 200 to the other gear stage state. It is easier to avoid the power cut-off state of the sub-transmission device 200 when the operation control for shifting to one of the gear positions is performed.

That is, the difference between the vehicle speed (output shaft speed) in the power cut-off state and the vehicle speed at the one gear is smaller than the difference between the vehicle speed at the other gear.
Accordingly, when the shifter 209 is returned from the power shut-off position to the pre-shift position, the movement resistance of the link mechanism constituted by the sub-shift actuator 81, the sub-shift operating mechanism, and the shifter 209 causes the shifter 209 to move to the power shut-off position. This is smaller than the movement resistance when moving from the shift position to the post-shift position.

  The present invention is based on such a novel viewpoint, even though the auxiliary transmission actuator 81 performs an operation in accordance with an operation of the auxiliary transmission operation member 840 from one gear position to the other gear position. When the sub-transmission device 200 is in a power cut-off state, the control device 800 causes the sub-transmission actuator to shift to one of the gear positions in which the sub-transmission device 200 has been engaged most recently. 81 is configured to control the operation.

Therefore, the sub-transmission device 200 is powered off even though the sub-transmission actuator 81 performs an operation corresponding to the operation from one of the high speed position and the low speed position of the sub transmission operation member 840 to the other. It can be prevented as quickly as possible from continuing to be in a state.
Further, the shifter 209 is prevented from being continuously pushed toward the target position by the auxiliary transmission actuator 81. Therefore, it is possible to effectively prevent wear and / or damage to the concavo-convex engaging portions in each of the shifter 209, the driven gear 207 of the high-speed gear train, and the driven gear 208 of the low-speed gear train.

  In the present embodiment, the sub-transmission actuator 200 returns the sub-transmission device 200 to the shift state before the operation of the sub-transmission operation member 840 when the sub-transmission device 200 fails to shift to the other gear. After performing the operation control 81 (step S27), based on the signal from the sub-shift detection sensor 850, whether or not the sub-transmission device 200 has returned to the shift state before the operation of the sub-shift operation member 840 is determined. If it is determined by the control device 800 (step S28) and the shift to the pre-operation speed change state has failed (No in step S28), a predetermined traveling system abnormality process is executed (step S29).

The traveling system abnormality process controls various mechanisms inserted in the traveling system transmission path so as to stop the working vehicle 1 as quickly as possible without suddenly stopping.
In the present embodiment, 1) the clutch mechanism (that is, the traveling system hydraulic switching unit 300 in the present embodiment) inserted in the traveling system transmission path is set in a power cut-off state, and 2) the HST 110 There is at least one of controlling the operation of the output adjusting member 115 to a position where the vehicle speed becomes zero.
Further, as the traveling system abnormality process, an alarm (second alarm) indicating that the return shift operation to the one shift state of the auxiliary transmission 200 has failed is displayed on the display unit 880.
As another traveling system abnormality process, for example, when the drive source 10 is an output variable type, the drive source 10 can be set to a low output state (idling state) or the like. .

  As described above, when the shift to the other gear stage fails, the position of the sub-shift operation member 840 is further detected and confirmed in multiple stages, so that the abnormality can be detected at an early stage and the traveling system abnormality can be detected. By performing the process, it is possible to prevent the work vehicle 1 from being in a dangerous state such as being unable to be steered or being suddenly stopped.

  On the other hand, when the auxiliary transmission device 200 has succeeded in shifting to the other gear position (Yes in step S25), the control device 800 does not change the vehicle speed before and after the operation of the auxiliary transmission operation member 840 ( The main speed change actuator 830 is controlled to operate so that no speed change shock occurs (step S30).

In this case, the operation of the main transmission actuator 830 is controlled by the control device 800 so that the vehicle speed does not change before and after the operation of the auxiliary transmission operation member 840 (no transmission shock occurs), whereby the output rotation of the HST 110 is performed. The number is controlled.
More specifically, the vehicle speed sensor 860 detects the vehicle speed at the start of the speed change operation of the subtransmission device 200, and the sub speed change operation detection sensor 890 detects the other speed stage. The output speed of the HST 110 is calculated by the control device 800 so that the vehicle speed is substantially equal to the vehicle speed in the speed ratio at the other speed stage, and the main transmission actuator 830 is set to the calculated output speed. The operation is controlled.
It should be noted that in the control amount of the main transmission actuator 830, it is also possible to take into account the change in vehicle speed during the time (idle running period) until the auxiliary transmission 200 is engaged with the other shift stage.

When the control as described above is not performed, if the output rotation speed of the HST 110 is constant before and after the operation of the auxiliary transmission operation member 840, the driving wheel 30 is switched by switching the gear stage engaged in the auxiliary transmission device 200. Since the rotational speed of the vehicle changes in accordance with the gear ratio of the gear stage to be engaged, the traveling state of the work vehicle 1 is jerky and the traveling feeling is deteriorated.
In contrast, in the above configuration, the main transmission actuator 830 is controlled by the control device 800 so that the vehicle speed does not change before and after the operation of the auxiliary transmission operation member 840. Travel stability can be improved.

The embodiment according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various improvements, changes, and modifications can be made without departing from the spirit of the present invention.
For example, the auxiliary transmission actuator 81 in the present embodiment is configured to electrically detect the operation amount of the auxiliary transmission operation member 840 that can be manually operated and to hydraulically control the auxiliary transmission valve 80. In a working vehicle that does not perform control at the time of switching abnormality in the transmission 200, a configuration may be adopted in which the shifter 209 is operatively connected to the shifter 209 via a mechanical link instead of the above configuration.

FIG. 1 is a side view of a working vehicle to which a continuously variable transmission output control structure according to an embodiment of the present invention is applied. FIG. 2 is a schematic diagram of transmission in the working vehicle of FIG. FIG. 3 shows the rotation speed of the combined output shaft (HMT output shaft) and the rotation speed of the speed change output shaft when the input rotation speed (rotation speed of the transmission shaft) of the HST to the hydraulic pump body is constant in this embodiment. It is a relationship diagram with the motor output shaft rotation speed of HST. FIG. 4 is a hydraulic circuit diagram of the working vehicle of FIG. FIG. 5 is a schematic configuration diagram relating to the control system of the working vehicle of FIG. FIG. 6 is a rotary encoder output diagram of the highest speed setting sensor in the present embodiment. FIG. 7 is a flowchart regarding the maximum speed setting member operation amount detection process in the maximum speed setting control in the present embodiment. FIG. 8 is a schematic view of a display provided in the work vehicle in the present embodiment. FIG. 9 is a graph of a control function of HST calculated in the initial adjustment mode. FIG. 10 is a cross-sectional configuration diagram of the auxiliary transmission device and the auxiliary transmission actuator in the working vehicle of the present embodiment. FIG. 11 is a flowchart relating to a switching abnormality process in the auxiliary transmission actuator control in the present embodiment.

1 Working Vehicle 10 Drive Source 30 Main Drive Wheel 110 HST (Continuously Variable Transmission)
800 Controller 810 Main transmission operation member 820 Main transmission operation detection sensor 830 Main transmission actuator 860 Vehicle speed sensor

Claims (3)

A hydraulic continuously variable transmission as a main transmission that is inserted in a traveling system transmission path from the drive source to the drive wheel, and a synchronous output from the drive source and a shift output from the continuously variable transmission are synthesized. The planetary gear unit that outputs from the composite output member, the main transmission operation member that can be operated manually, the main transmission operation detection sensor that detects the operation position of the main transmission operation member, and the output adjustment member of the continuously variable transmission are moved. A main speed change actuator, a vehicle speed sensor for directly or indirectly detecting the rotational speed of the drive wheel, and a target speed of the drive wheel corresponding to the operation amount of the main speed change operation member by the main speed change detection sensor. A continuously variable transmission output control structure applied to a work vehicle including a control device that is input and controls the operation of the main transmission actuator based on the input signal,
In the continuously variable transmission and the planetary gear unit, when the speed change output of the continuously variable transmission is a predetermined speed in the reverse direction, the rotational speed of the combined output member becomes zero and the speed change output of the continuously variable transmission is The rotational speed of the composite output member is increased as the rotational speed is increased from zero in the reverse rotation direction to zero in the forward rotation direction.
The control device has a normal control mode, an initial adjustment mode for adjusting a relationship between an output of the continuously variable transmission and an operation amount of the main transmission operation member,
In the initial adjustment mode,
In a range where the speed change output of the continuously variable transmission is in the forward rotation direction, the main speed change actuator is operated based on the vehicle speed sensor so that the rotational speed of the drive wheel becomes a predetermined first speed, The operation control amount at that time is stored as a first operation control amount,
Within the range where the speed change output of the continuously variable transmission is in the reverse rotation direction, the main speed change is performed based on the vehicle speed sensor so that the rotational speed of the drive wheels is a predetermined second speed different from the first speed. Actuating the actuator, storing the operation control amount at that time as the second operation control amount,
By performing linear interpolation based on the first and second operation control amounts, a control function for a change in rotational speed of the drive wheel with respect to the operation control amount of the main transmission actuator is calculated and stored.
In the normal control mode, an operation control amount of the main transmission actuator corresponding to the target rotational speed input by the main transmission operation detection sensor is calculated using the control function calculated in the initial adjustment mode, and is calculated A continuously variable transmission output control structure for controlling the operation of the main transmission actuator based on the operation control amount. Before Stories second speed is continuously variable transmission output control structure according to claim 1, characterized in that a zero.   In the normal control mode, the control device calculates a difference between the target rotational speed and the rotational speed of the driving wheel detected by the vehicle speed sensor when controlling the operation of the main transmission actuator based on the control function. 3. The continuously variable transmission output control structure according to claim 1, wherein the main transmission actuator is feedback-controlled so as to eliminate the difference.

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