JP2022169120A - work vehicle - Google Patents

Abstract

To provide a work vehicle which controls a continuously variable transmission via an actuator, in which a control unit is configured to be able to smoothly and surely perform control into the neutral state even in a case where the continuously variable transmission is operated into the neutral state from the advancement side or operated into the neutral state from the backward travel side.SOLUTION: A work vehicle comprises: a traveling machine body; a hydraulic continuously variable transmission; operation detection means which detects the operation of a shifting operation tool; an operation member which operates the hydraulic continuously variable transmission; a motor which operates the operation member; and a control unit. The control unit, when performing the operation of shifting the hydraulic continuously variable transmission into the neutral state by the shifting operation tool in such a state that the traveling machine body is traveling backward, is configured to control the continuously variable transmission into the neutral state by performing the backward travel stop operation of operating the operation member to the first operation position after passing through a prescribed third operation position preset on the advancement side with respect to the first operation position from the backward travel side.SELECTED DRAWING: Figure 8

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work vehicle provided with a control section that controls gear shifting operations of a traveling machine body.

A traveling machine body having a control section for a traveling operation by an operator, a hydraulic stepless transmission for shifting the traveling power of the traveling machine body, and a gear shift operation of the hydraulic stepless transmission provided in the control section. an operation position detection means for detecting an operation position of the gear shift operation tool; and moving the hydraulic stepless transmission into a forward state, a neutral state, or a reverse state in accordance with the operation position of the speed change operation tool. and a control unit for controlling the shift to the forward side, wherein the control unit shifts the hydraulic stepless transmission to the forward side when the shift operation device is operated to one side from the neutral position to the forward position. A work vehicle disclosed in Patent Document 1 is conventionally known, in which the hydraulic continuously variable transmission is configured to shift to the reverse side when the speed change operation tool is operated from the neutral position to the reverse position on the other side. .

According to the work vehicle of the above document, the speed change operation of the continuously variable transmission can be performed by an electric operation system via an electric actuator, and the hydraulic continuously variable transmission is operated from the forward side to the neutral position. Since the operating position of the hydraulic continuously variable transmission varies depending on whether it is operated from the reverse side or to the neutral position, the traveling machine body may perform an unintended operation when the gear shift operation tool is operated to the neutral position. In addition to this, there is a problem that it takes time and effort to make adjustments to correct this.

Japanese Patent No. 3635823

The present invention provides a work vehicle that controls the continuously variable transmission via the actuator, wherein the control unit maintains the neutral state from the reverse side even when the continuously variable transmission is operated from the forward side to the neutral state. To provide a work vehicle configured to smoothly and reliably switch to a neutral state even when a switching operation is performed to a neutral state.

In order to solve the above-mentioned problems, the present invention firstly comprises a traveling machine body having a control section for a traveling operation by an operator, a hydraulic continuously variable transmission for changing the traveling power of the traveling machine body, and a shift operation tool for performing a shift operation of the hydraulic continuously variable transmission, an operation detection means for detecting the operation of the shift operation tool, an operating member for operating the hydraulic continuously variable transmission, and the a motor that operates an operation member; and a control unit that shifts the hydraulic stepless transmission to a forward state, a neutral state, or a reverse state by controlling the drive of the motor according to the operation of the gear shift operation tool. wherein the control unit stores in advance, as an operation position of the operation member, a first operation position at which the stepless transmission can be shifted from the forward side to a neutral state, and the control unit stores the traveling machine body is traveling forward, when the speed change operation tool is operated to shift the hydraulic continuously variable transmission to the neutral state, the operation member is operated from the forward side as it is to the first operation position to stop the forward movement. When the stepless transmission is put in the neutral state by the operation, and when the gear shift operating device is operated to shift the hydraulic stepless transmission to the neutral state while the traveling machine body is traveling in reverse. and the stepless speed change is performed by operating the operating member from the reverse side to the first operating position after passing through a predetermined third operating position that is preset to the forward side rather than the first operating position. It is characterized in that it is configured to control the device to a neutral state.

Secondly, a traveling machine body having a control section for a traveling operation by an operator, a hydraulic stepless transmission for shifting the traveling power of the traveling machine body, and the hydraulic stepless transmission provided in the control section. A shift operation tool for performing a shift operation, an operation detection means for detecting an operation of the shift operation tool, an operation member for operating the hydraulic stepless transmission, a motor for operating the operation member, and the shift a control unit that shifts the hydraulic continuously variable transmission to a forward state, a neutral state, or a reverse state by controlling the drive of the motor according to the operation of the operation tool, wherein the control unit As operating positions of the member, a first operating position in which the stepless transmission can be operated from the forward side to the neutral state, and a second operating position in which the stepless transmission can be operated from the reverse side to the neutral state. is stored in advance, and when the gear shift operation device is operated to shift the hydraulic continuously variable transmission to a neutral state while the traveling machine body is traveling forward, the control unit controls the operation member is operated from the forward side to the first operation position as it is to put the stepless transmission in a neutral state, and in a state in which the traveling machine body is traveling backward, the hydraulic stepless speed change operation device is operated. When the transmission is operated to shift to the neutral state, the stepless transmission is controlled to the neutral state by performing a reverse stop operation in which the operation member is operated from the reverse side to the second operation position as it is. It is characterized by being composed

Thirdly, a manual switching operation tool for manually switching the hydraulic continuously variable transmission to a neutral state via the operating member separately from the speed change operation tool, and detecting the operation of the manual switching operation tool. a manual operation detection sensor, wherein the manual switching operation tool is configured to operate the operation member to the first operation position; is detected, the operating member is operated to stop the backward movement when it is detected that the switching operation of the manual switching operation device executed in the first step is canceled.

Fourthly, the manual switching operation tool is a brake operation tool.

Fifth, a torque limiter type clutch is provided between the motor and the operating member, and the clutch comprises a pawl clutch portion that is idly rotated around a support shaft driven by the motor and faces the pawl clutch portion. It has a meshing portion that rotates integrally with the support shaft, an inclined portion that is formed in each of the clutch portion and the meshing portion along the rotational direction, and a biasing member that biases the claw clutch portion or the meshing portion. , when the brake pedal is stepped on, the power transmission between the motor and the operating member is cut off, and the clutch is configured to disengage when the brake operating tool is manually operated, It is characterized in that the inclined portion is configured to fall within the range of the amount of deviation that occurs when the operating member is operated to the first operating position and to the second operating position.

Sixthly, the control unit is configured to drive the motor in the direction in which the operation member is operated when the stepping operation of the brake pedal is detected.

According to the control unit, when an operation to shift the hydraulic continuously variable transmission to a neutral state is performed by the speed change operation device while the traveling machine body is traveling forward, the operation member is operated to stop the forward movement. By doing so, the stepless transmission is placed in a neutral state, and when the gear shift operating device is operated to shift the hydraulic stepless transmission to the neutral state while the traveling machine body is traveling backward, By operating the operation member to stop the reverse movement, the motor can be controlled so that the continuously variable transmission is placed in the neutral state. The continuously variable transmission having hysteresis characteristics can be reliably and accurately controlled to shift to the neutral state.

In addition to the speed change operation tool, a manual switching operation tool for manually switching the hydraulic continuously variable transmission to a neutral state via the operation member, and a manual operation for detecting the operation of the manual switching operation tool. and a detection sensor, wherein the manual switching operation tool is configured to be able to operate the operation member to the first operation position, and the control section is executed when the continuously variable transmission is in the reverse state. According to the structure configured to operate the operation member to stop the backward movement when the cancellation operation of the switching operation of the manual switching operation tool is detected, even when the manual switching operation tool is operated, It is possible to more reliably operate the hydraulic continuously variable transmission into the neutral state. In addition, the manual switching operation device allows the stepless transmission to be operated with high accuracy only by mechanical linkage when switching from the forward side, which is frequently used, to the neutral state, thereby improving safety.

Further, in the case where the manual switching operation device is a brake pedal, the braking operation and the operation to the neutral state of the continuously variable transmission are simultaneously performed by depressing the brake pedal, so that the running speed is reduced. The machine can be stopped more reliably.

Further, a torque limiter type clutch is provided between the motor and the operating member, and the clutch includes a pawl clutch portion that is driven by the motor and idles around a support shaft, and a pawl clutch portion that faces and supports the pawl clutch portion. The brake pedal has a meshing portion that rotates integrally with a shaft, an inclined portion that is formed along the rotational direction of the clutch portion and the meshing portion, and a biasing member that biases the pawl clutch portion or the meshing portion. When the stepping operation is performed, the power transmission between the motor and the operating member is cut off, and the clutch is configured such that when the brake operating tool is manually operated, the inclined portion is According to the configuration in which the amount of deviation between when the operating member is operated to the first operating position and when the operating member is operated to the second operating position is within the range of the amount of deviation, even when the brake is operated from the backward traveling state, the above-mentioned Since the clutch can be smoothly connected and the continuously variable transmission can be reliably operated in a neutral state, safety is further improved.

The control unit is configured to drive the motor in the direction in which the operation member is operated when the stepping operation of the brake pedal is detected. When the is stepped on, the motor can be prevented from being damaged, and the clutch is smoothly connected after the brake operation is released. It is possible to prevent the occurrence of lag due to useless rotational driving of the motor until it is connected.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall side view of a riding rice transplanter (transplanter) to which the work vehicle of the present invention is applied; BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall plan view of a ride-on rice transplanter (transplanter) to which the working vehicle of the present invention is applied; FIG. 3 is a side view of a main part showing a steering mechanism and an HST control mechanism; Fig. 3 is a front perspective view of a main part showing a steering mechanism and an HST control mechanism; FIG. 4 is a rear perspective view of a main part showing a steering mechanism and an HST control mechanism; FIG. 4 is an enlarged view of a main part showing an operation arm for operating a traveling HST; (A) and (B) are main part side views showing the brake operation linking mechanism before and during operation of the brake operation tool. (A) is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST when switching the traveling HST from the forward side to the neutral state in HST neutral shift control, and (B) is a graph showing the HST neutral gear shifting. 4 is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST when the traveling HST is switched from the reverse side to the neutral state in control, and (C) shows another embodiment of the HST neutral shift control. 4 is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST. It is a block diagram of a control part. 4 is a processing flow diagram showing HST neutral shift control; FIG.

1 and 2 are an overall side view and an overall plan view of a riding rice transplanter (transplanter) to which the working vehicle of the present invention is applied. This riding rice transplanter comprises a traveling machine body 3 supported by a pair of left and right front wheels 1, 1 and rear wheels 2, 2, and a planting machine connected to the rear of the traveling machine body 3 via an elevating link 4 so as to be vertically movable. It is equipped with a machine 6.

The body frame 8 that supports the traveling body 3 includes an engine (not shown) surrounded by a bonnet 9 in front, and a travel HST (hydraulic stepless transmission) that continuously changes the engine power input from the engine. , hydraulic transmission) 10, and a mission case 11 to which the power output from the traveling HST 10 is input. A control unit 7 is provided to perform the operation.

The operation unit 7 includes a seat 12 on which an operator sits, a steering handle 13 for steering the traveling body 3 (front wheels 1) via a steering mechanism 20 described later, A main transmission lever (transmission operation tool, forward/backward switching lever) 14 which is provided and is operated to swing back and forth at least; A floor step 17 and a brake pedal (manual switching operation tool) 18 which is depressably provided on the front side of the floor step 17 and operates the brake operation (braking) of the traveling machine body 3 are arranged.

The main shift lever 14 is provided with a switch operation tool 14a disposed at a grip portion on the upper end side so as to be pushable while being gripped by an operator. The switch operating tool 14a is a changeover switch (switching operating tool) for switching to a low speed mode for reducing the shift amount of the traveling body 3 operated by the main shift lever 14. As shown in FIG.

The main shift lever 14 is configured to be able to swing back and forth from a basic position (neutral position) tilted slightly forward, and when the front and rear swing operation of the main shift lever 14 is released (the main shift lever 14 The main shift lever 14 automatically returns to the neutral position (see FIG. 3, etc.). In addition, the main gear shift lever 14 detects the presence or absence of a shift operation by the main gear shift lever 14 and the swing operation amount from the neutral position by an operation position detection potentiometer (operation detection means, operation position detection sensor) 46 . configured to be able to

As a result, the control unit 50, which will be described later, detects an operation of returning the main shift lever 14 to the neutral position within a predetermined period of time after swinging the main shift lever 14 back and forth from the neutral position (hereinafter referred to as stepped shift operation). In this case, it is detected that the traveling HST 10 is operated to shift gears in a stepwise manner, and that the main transmission lever 14 is rocked back and forth from the neutral position for a predetermined period of time or more (hereinafter referred to as stepless gear shift operation). is configured to be able to execute HST shift control for steplessly shifting the traveling HST 10 in accordance with the operation amount and operation time of the main shift lever 14 . The HST shift control may be configured to correspond to only one of stepped and stepless.

Along with this, the traveling HST 10 is controlled by controlling the trunnion shaft 35 for shifting the traveling HST 10 in accordance with the operation of the main shift lever 14, so that the traveling HST 10 is moved forward, stopped, and reversed. An HST control mechanism 30 is provided which can switch between states. A specific configuration of the HST control mechanism 30 will be described later.

The brake pedal 18 includes a tread plate portion 18a to be stepped on by an operator, a rod-shaped extension portion 18b extending downward and rearward from the tread plate portion 18a in a U-shape, and the extension portion 18b. It has a shaft support portion 18c that supports the rear end side of the floor step on a horizontal support shaft 15 arranged below the floor step, and the footboard portion 18a is urged to the initial position where the footboard portion 18a is swung ( See FIG. 5, etc.). The brake pedal 18 (the shaft support portion 18c thereof) is provided with a brake operation linking mechanism 40 for switching the traveling HST 10 to a neutral state (neutral state) via the HST control mechanism 30. Details will be described later.

The planting machine 6 includes a seedling table 22 on which seedlings to be planted in a field are placed, and a planting section 23 for planting the seedlings placed on the seedling table 22 in the field. , and is operated to move up and down with respect to the traveling body 3 via the elevating cylinder 4, and the power transmitted from the engine is intermittently transmitted via a planted clutch (not shown).

Next, the steering mechanism and the HST control mechanism will be described with reference to FIGS. 3 to 5 are a side view, a front perspective view, and a rear perspective view of essential parts showing the steering mechanism and HST control mechanism, and FIG. 6 shows the operating arm for operating the traveling HST. It is a part enlarged view.

The steering mechanism 20 includes the steering shaft extending in the vertical direction, the transmission case 11 which is arranged between the left and right front wheels 1, 1, and which is internally equipped with transmission gears for changing the speed of the engine power. A pitman arm (not shown) supported on the lower surface side of the transmission case 11 so as to freely swing left and right; a power steering device 32 arranged below the steering shaft 19 and on the upper surface side of the transmission case 11; A cylindrical steering column 31 through which a steering shaft 19 is inserted is provided, and a U-shaped support bracket 33 with an open top is provided on the upper side of the power steering device 32 .

The HST control mechanism 30 is attached to a support shaft 36 supported so as to pass through the left and right side surfaces of the support bracket 33 in the left-right direction, and to be vertically swingable about the support shaft 36. A swing arm 37 mounted outside the left side of the support bracket 33, an operation arm 38 pivotally supported so as to rotate integrally with a trunnion shaft 35 for shifting the traveling HST 10, and an upper end side of the swing arm 38. a vertical operating rod 39 connected to the moving arm 37 side and having a lower end connected to the operating arm 38 side; The control unit 50 is provided, and the torque limiter type clutch 41 is provided on the left end side of the support shaft 36 (see FIGS. 3 to 5, etc.).

The HST control mechanism 30 is provided with a brake operation linkage mechanism 40 for manually operating the traveling HST 10 via the brake pedal 18, so that the traveling HST 10 can be directly operated by an operator's manual operation. (see FIGS. 5 to 7, etc.). A specific configuration of the brake operation linking mechanism 40 will be described later.

According to this configuration, the HST control mechanism 30 axially rotates the support shaft 36 by the driving force of the motor 42, and the swing arm 37 is vertically swung by the axial rotation of the support shaft 36, thereby The operation rod 39 is moved up and down by the vertical rocking movement of the moving arm 37, and the operation position of the operation arm 38 for operating the trunnion shaft 35 can be operated by the vertical movement of the operation rod 39. (See FIGS. 4 to 6, etc.).

At this time, an operation arm detection potentiometer 47 for detecting the operation position of the operation arm 38 is provided on the operation arm 38 side, and the control section 50 detects the operation position of the operation arm 38 to detect the operation position of the operation arm 38. , the shift state of the traveling HST 10 can be confirmed (see FIG. 6, etc.).

According to the above-described configuration, the control unit 50 controls the shift operation (back and forth swing operation) of the main shift lever 14 detected by the operation position detection potentiometer 46 and the current state detected by the operation arm detection potentiometer 47 . The HST shift control for controlling the shift operation of the traveling HST 10 can be executed by controlling the driving of the motor 42 based on the shifting state of the traveling body 3 (traveling HST 10).

Incidentally, the traveling HST 10 that is operated via the HST control mechanism 30 described above has an operating position of the operating arm 38 (trunnion shaft 35) and a position of the traveling HST 10, as shown in FIG. It has a hysteresis characteristic in relation to the output rotation. Specifically, the traveling HST 10 is positioned at a forward stop position (first operating position) P1, which is the operating position of the operating arm 38 (trunnion shaft 35) when switching from the forward output state (forward state) to the neutral state. , and the reverse stopping position (second operating position) P2, which is the operating position of the operating arm 38 (trunnion shaft 35) when switching from the reverse output state (backward traveling state) to the neutral state (see FIG. 8). ).

In order to deal with this, the control unit 50 is controlled when the gear shift lever 14 is operated to switch the traveling HST 10 to the neutral state while the traveling machine body 3 is traveling forward, and when the traveling machine body 3 is traveling backward. In both cases, the operating arm 38 (trunnion shaft 35) is operated so that the traveling HST 10 is reliably switched to the neutral state. HST neutral shift control to be controlled is configured to be executable. Specific details of the HST neutral shift control will be described later.

The clutch 41 is provided outside the left side surface of the support bracket 33 and on the left end side of the support shaft 36 so as to rotate integrally therewith. A drive gear 41A that idles around the support shaft 36, a torque limiter type clutch portion 41B that interrupts transmission of power between the drive gear 41A and the support shaft 36, and a clutch portion 41B that is connected to the drive gear 41A. and an elastic member (biasing member) 41C that biases to the side (see FIG. 3, etc.).

As a result, when the support shaft 36 (driving gear 41A) rotates with a torque stronger than the driving force of the motor 42 (biasing force of the elastic member), the clutch 41 can rotate the motor 42 and the support shaft 36. is configured to disconnect power transmission between the

In other words, when the motor 42 is driven, the clutch 41 can operate the swing arm 37 (operation arm 38) via the support shaft 36, while the brake operation linking mechanism 40 can operate. to prevent the operation force from being transmitted to the motor 42 when the support shaft 36 (operation arm 37) side is operated with a force (torque) greater than the driving force of the motor 42. configured to be able to

More specifically, the motor 42 is arranged on the upstream transmission side of the clutch 41 , while the support shaft 36 →the rocking arm 37 →the operating rod is arranged on the downstream transmission side of the clutch 41 . Power is transmitted in the order of 39→the operation arm 38→the trunnion shaft 35 to link with the traveling HST10. The brake operation linking mechanism 40, which will be described later, operates the trunnion shaft 35 to a neutral state by operating the support shaft 36 with the operation force of stepping on the brake pedal 18. As shown in FIG. A specific description will be given below.

Next, based on FIGS. 3 to 7, the configuration of the brake operation linking mechanism will be specifically described. FIGS. 7A and 7B are side views of main parts showing the brake operation linking mechanism before and during operation of the brake operation tool.

The brake operation linking mechanism 40 includes a rocking piece 51 provided on the shaft support portion 18c of the brake pedal, and a rocking piece 51 extending forward from the rocking piece 51 to push forward and backward in accordance with the operation of the brake pedal 18. A linking rod 52 to be pulled, a first linking arm 53 connected to the front end of the linking rod 52 and swinging back and forth, and a swinging operation of the first linking arm 53 to swing vertically. A second linking arm 54, a linking arm support shaft 56 that pivotally supports the first linking arm and the second linking arm 54, and a diamond shape that rotates integrally with the support shaft 36 on the right end side of the support shaft 36. a first linking member 58 in the vertical direction for linking the front end side of the brake operation linking arm 57 and the second linking arm 54; the rear end side of the brake operation linking arm 57 and the A vertical second linking member 59 for linking with the second linking arm 54 is provided (see FIG. 7, etc.).

Flexible holes 58a and 59a, which are long holes along the vertical direction, are formed in the upper end side of the first linking member 58 and the upper end side of the second linking member. are connected to the front and rear ends of the brake operation linking arm 57 (see FIG. 7(A)).

At this time, when the support shaft 36 is rotated via the motor 42 in a state in which the brake pedal 18 is not stepped on (see FIG. 7A), the flexible holes 58a and 59a are opened. , the brake operation linking arm 57 is configured to swing within the range of the flexible holes 58a and 59a.

On the other hand, when the brake pedal 18 is stepped on (see FIG. 7(B)), the flexible holes 58a and 59a are arranged such that the brake pedal 18→the rocking piece 51→the connecting rod 52→ By linking in the order of the first linking arm 53→the linking arm support shaft 56→the second linking arm 54→the first linking member 58→the brake operation linking arm 57, the support shaft 36 is moved in a predetermined direction. It is constructed so that it can be rotated.

As a result, when the brake pedal 18 is stepped on, the brake operation linking mechanism 40 rotates the support shaft 36 through mechanical linking, thereby actuating the HST control mechanism 30 and causing the brake pedal 18 to operate. It is configured such that the arm 38 (trunnion shaft 35) can be operated to the first operating position P1.

According to this configuration, the brake operation linking mechanism 40 is controlled by the control unit 50 when the brake pedal 18 is depressed while the traveling body 3 (traveling HST 10) is in the forward state. Regardless of the driving state of the motor 42, the traveling HST 10 can be forcibly operated to the neutral state (stopped state) to stop the traveling body 3 more reliably. Note that the HST neutral shift control is such that when the brake pedal 18 is depressed (braking operation) while the traveling machine body 3 (traveling HST 10) is in the reverse state, the traveling HST 10 is shifted when the braking operation is released. is configured to control the operating arm 38 so as to reliably switch to the neutral state. Specific details of the HST neutral shift control will be described later.

Incidentally, when the support shaft 36 (traveling HST 10) is operated via the brake operation linking mechanism 40 by depressing the brake pedal 18, the support shaft 36 is moved by the clutch 41. It is configured to reliably prevent shaft rotation from being transmitted to the motor 42 side. According to the action of the clutch 41, even if the traveling HST 10 is forcibly changed gears by an operator's brake operation (manual operation), the motor 42 is not forced to rotate. It is possible to prevent a situation in which an unnecessary load is applied to the device and the device breaks down.

Further, the clutch 41 includes the drive gear portion 41A, the clutch portion 41B, inclined portions 60A and 60B formed in the drive gear portion 41A and the clutch portion 41B, respectively, along the rotational direction, and the elastic portion 60B. The clutch 41 has a member (biasing member) 41C (see FIG. 5). may be configured to fall within the range of the amount of deviation between when is operated to the first operation position and when is operated to the second operation position.

According to this configuration, even if the brake is operated in the backward state, the clutch is smoothly connected by the biasing force of the biasing member 41C after the brake operation. can be performed without lag.

Further, when the brake operation by the brake pedal 18 is detected, the control unit 50 drives the motor 42 along the rotation direction in which the support shaft 36 is operated by the brake operation linking mechanism 40, The clutch 41 is configured to be in the connected position. That is, the driving direction of the motor 42 differs depending on whether the braking operation is performed while the traveling body 3 is moving forward or when the traveling body 3 is moving backward.

According to this configuration, the motor 42 can be driven in the same direction as the direction in which the shaft rotation of the support shaft 36 is operated via the brake operation linking mechanism 40 when the brake is operated. It is possible to prevent a situation in which an extra load in the reverse rotation direction is applied to cause a failure.

Furthermore, when the brake operation by the brake pedal 18 is detected, the control unit 50 (HST shift control) does not detect that the main shift lever 14 has been temporarily moved to the neutral position after releasing the brake operation. As far as possible, the movement of the traveling machine body 3 (traveling HST 10) in the forward and backward directions due to the rocking operation of the main transmission lever 14 is restricted.

According to this configuration, when the brake operation by the brake pedal 18 is released, the operating position of the main gearshift lever 14 is operated to a position other than the neutral position, thereby surely preventing the traveling machine body 3 from suddenly starting. can be prevented.

Next, based on FIGS. 8 to 10, the control contents of the HST neutral shift control by the control section will be explained. FIG. 8A is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST when switching the traveling HST from the forward side to the neutral state in HST neutral shift control, and FIG. 8(C) is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST when switching the traveling HST from the reverse side to the neutral state in the HST neutral shift control. FIG. 9 is a graph showing the relationship between the operating position of the trunnion shaft and the output rotation of the traveling HST, showing another embodiment.

In the HST neutral shift control, when the traveling HST 10 is switched from the forward state to the neutral state by the shift operation of the main gearshift lever 14 (the traveling body traveling forward is stopped), the traveling HST 10 is shifted from the forward side to the neutral state. In order to switch to the state, the operating arm 38 (trunnion shaft 35) is operated from the forward side toward the forward side stop position (first operation position) P1 as it is to perform a "forward stop operation" (Fig. 8 (A )reference).

In the HST neutral shift control, when the traveling HST 10 is switched from the reverse state to the neutral state by the shift operation of the main shift lever 14, the operation arm 38 (trunnion shaft 35) is moved from the reverse side to the reverse side stop. After operating to the forward side to a predetermined reverse stop via operation position (third operation position) P3 set on the forward side of the position (second operation position) P2, the forward stop position (first operation position) is reached. It is configured to execute an operation to return to P1 (hereinafter referred to as “reverse stop operation”) (see FIG. 8B).

At this time, the reverse operation position (second operation position) P2, which is the operation position of the operation arm 38, is an operation position where the traveling HST 10 can be switched from the reverse state to the neutral state as it is (see FIG. 8). , the intermediate operation position (third operation position) P3 for stopping backward movement is an operation performed immediately after the traveling HST 10 starts outputting to the forward side from the neutral state (immediately after the traveling body 3 starts traveling forward). position (see FIG. 8B).

According to this configuration, both when the traveling HST 10 is operated from the forward side to the neutral state and when it is operated from the reverse side to the neutral state, the operating arm 38 (trunnion shaft 35) is finally moved from the forward side to the neutral state. Control to operate to the 1 operation position P1 is executed. As a result, both when the traveling HST 10 is operated from the forward traveling state to the neutral state and when the traveling HST 10 is operated from the reverse traveling state to the neutral state by the main gear shift lever 14, the traveling body 3 can be reliably stopped and unintentionally stopped. It is possible to more reliably prevent the situation of moving forward or backward.

Further, in the HST neutral shift control by the control unit 50, when it is detected that the brake is operated while the traveling HST 10 is operated to the reverse side, the operation arm 38 is controlled by the brake operation linking mechanism described above. is operated to the first operation position P1 from the reverse side, when an operation to release the brake operation is detected thereafter, the operation arm 38 (trunnion shaft 35) is moved to the first operation position via the motor 42. Position P1→(second operation position P2)→third operation position P3→(second operation position P2)→first operation position P1 By performing the reverse stop operation, the traveling HST 10 is reliably brought into a neutral state. (see FIG. 8(B)).

According to this configuration, even when the brake is operated while the traveling machine body 3 is moving backward, the traveling machine body 3 can be reliably stopped, and when the braking operation is released, the traveling machine body 3 can move forward and backward unintentionally. can be prevented from progressing.

According to the above configuration, the traveling HST 10 can be switched to the neutral state by operating the brake pedal 18 without operating the main shift lever 14, and the traveling body 3 can be reliably stopped. be. In addition, when the brake is operated from the forward state, which is relatively frequent, the traveling HST 10 can be operated to the neutral state by performing the forward stop operation of the operation arm 38 only by mechanical linkage (brake operation linkage mechanism 40). It also improves safety.

Next, another embodiment of HST neutral shift control will be described with reference to FIG. 8(C).

In the HST neutral shift control, the "forward stop operation" executed when the traveling HST 10 is switched from the forward state to the neutral state by the shift operation of the main shift lever 14 is performed in the same manner as in the above-described embodiment. This is executed when the arm 38 is operated from the forward side toward the forward side stop position (first operation position) P1 as it is, and the traveling HST 10 is switched from the reverse state to the neutral state by the shift operation of the main shift lever 14. The "reverse stop operation" may be an operation in which the operating arm 38 is directed from the reverse side to the reverse side stop position (second operation position) P2 (see FIG. 8C).

According to this configuration, when the traveling HST 10 is switched from the reverse state to the neutral state by the shift operation of the main gearshift lever 14, the traveling HST 10 can be smoothly switched to the neutral state without extra operation. In addition to eliminating the slightly moving behavior of the body 3, the load on the motor 42 and the traveling HST 10 is reduced.

According to the above-described HST neutral control, the operating position of the operating arm 38 (trunnion shaft 35) is set to the first operating position for switching the traveling HST 10 from the forward side to the neutral state, and the The operating position (second operating position) and the third operating position on the forward side of the second operating position of the operating arm 38 when switching the travel HST 10 from the reverse side to the neutral state are stored in the control unit 50. As a result, the hysteresis characteristic of the traveling HST 10, which has conventionally been mechanically adjusted by operating the main shift lever 14 or the like, can be smoothly and accurately adjusted by control.

FIG. 9 is a block diagram of the control unit, and FIG. 10 is a processing flow diagram showing HST neutral shift control.

On the input side of the control unit 50, there are the operating position detection potentiometer 46 for detecting the operating position of the main shift lever 14 and the operating arm detecting potentiometer 47 for detecting the operating position of the operating arm 38 (trunnion shaft 35). , and a brake operation detection sensor (brake operation detection potentiometer, manual operation detection sensor) 48 capable of detecting brake operation and brake release operation by detecting the operation position of the brake pedal 18 is connected, and the control unit The motor 42 is connected to the output side of 50 (see FIG. 9).

A processing flow of the HST neutral shift control will be described with reference to FIG. When the processing flow of the HST neutral shift control is started, the process proceeds to step S1.

In step S1, it is confirmed by the operating position detection potentiometer 46 and the operating arm detection potentiometer 47 whether or not the gear shift lever 14 has been operated to switch the traveling HST 10 from the forward side to the neutral state. If a shift operation for switching the traveling HST 10 from the forward state to the neutral state is detected, the process proceeds to step S2.

In step S2, the operating arm 38 (trunnion shaft 35) is operated from the forward side to the first operating position P1 by the motor 42 to perform a forward stop operation, thereby switching the traveling HST 10 to a neutral state, Then return.

According to this configuration, the operation of switching the traveling HST 10 to the neutral state by the shift operation by the main gearshift lever 14 is detected while the traveling HST 10 is in the forward traveling state, that is, the traveling body 3 is traveling forward. In this case, the forward stop operation is performed by operating the trunnion shaft 35 directly from the forward side to the first operation position via the motor 42, so that the traveling HST 10 can be reliably switched to the neutral state.

If it is not detected in step S1 that the shift lever 14 is operated to switch the traveling HST 10 from the forward state to the neutral state, the process proceeds to step S3.

In step S3, it is confirmed by the operation position detection potentiometer 46 and the operation arm detection potentiometer 47 whether or not the gear shift lever 14 has been operated to switch the traveling HST 10 from the reverse side to the neutral state. When a shift operation for switching the traveling HST 10 from the reverse state to the neutral state is detected, the process proceeds to step S4.

In step S4, the operating arm 38 (trunnion shaft 35) is operated by the motor 42 from the reverse side to the forward side through operation position (third operation position) P3. By performing the reverse stop operation to return to the 1 operation position P1, the traveling HST 10 is switched to the neutral state, and then returned.

According to this configuration, an operation of switching the traveling HST 10 to the neutral state by the gear shift operation by the main gearshift lever 14 is detected while the traveling HST 10 is in the reverse traveling state, that is, the traveling body 3 is traveling in the backward traveling state. In this case, after the trunnion shaft 35 is operated from the reverse side to the third operating position P3, which is the forward side, via the motor 42, the backward stop operation is performed to return it to the first operating position. can be reliably switched to the neutral state.

If it is not detected in step S3 that the shift lever 14 is operated to switch the traveling HST 10 from the reverse side to the neutral state, the process proceeds to step S5.

In step S5, it is confirmed by the brake operation detection sensor 48 whether or not the brake pedal 18 has been operated to brake, and if the brake pedal 18 has been depressed, the process proceeds to step S6. It should be noted that in step S5, if the brake operation by the brake pedal 18 is not detected, then the process returns.

In step S6, when the brake operation is detected, it is confirmed whether or not the traveling machine body 3 (the traveling HST 10) is traveling backward, and when it is detected that the traveling machine body 3 is traveling backward. , go to step S7. It should be noted that, in step S6, if the backward traveling of the traveling body 3 is not detected, that is, if the traveling body 3 is traveling forward or stopped, then the process returns.

According to this configuration, when the brake operation is performed while the traveling HST 10 is in the forward state (during forward traveling), the brake operation linking mechanism 40 causes the operation arm 38 to move in conjunction with the brake operation. Since the (trunnion shaft 35) is operated to the first operating position P1, the traveling HST 10 can be reliably shifted to the neutral state without controlling the operating arm 38 via the motor 42.

In step S7, it is confirmed by the brake operation detection sensor 48 whether or not the brake operation by the brake pedal 18 has been released. If the brake operation has been released, the process proceeds to step S8. It should be noted that, in step S7, if the release operation of the brake operation is not detected, the process returns to step S7 again.

In step S8, the operating arm 38 (trunnion shaft 35) is operated by the motor 42 from the first operating position P1 to the third operating position P3, and then from the third operating position P3 to the first operating position P1. By executing the reverse stop operation, the traveling HST 10 is switched to the neutral state, and then returned.

According to this configuration, when the braking operation is performed while the traveling HST 10 is in the reverse traveling state (during backward traveling), the brake operation linking mechanism 40 causes the operation arm 38 (the trunnion shaft 35) to travel backward. Since the driving HST 10 is operated to the first operation position P1 as it is from the side, the travel HST 10 is operated to a position slightly deviated from the neutral state to the reverse output side, and when the release of the brake operation is detected. , the operation arm 38 is operated to stop the reverse travel (operated to the third operation position on the forward side of the second operation position and then returned to the first operation position) via the motor 42, so that the traveling HST 10 is operated. can be reliably switched to the neutral state.

That is, when the brake operation is detected while the traveling body 3 is traveling forward, the traveling HST 10 is also automatically shifted to the neutral state by the mechanical configuration of the brake operation linking mechanism 40, and When the brake operation is detected while the traveling machine body 3 is traveling backward, the traveling HST 10 can be reliably switched to the neutral state by operating the trunnion shaft 35 to stop the backward movement when the braking operation is released. .

3 traveling body 10 traveling HST (hydraulic stepless transmission)
14 Main shift lever (shift operation tool)
18 brake pedal (manual switching operation tool)
35 trunnion shaft (operating member)
38 operating arm (operating member)
41 Clutch 41A Drive gear portion (claw clutch portion)
41B Clutch portion (meshing portion)
41C elastic member (biasing member)
42 motor 47 operation position detection potentiometer (operation detection means)
48 brake operation detection sensor (manual operation detection sensor)
50 control section 60 inclined section

Claims (6)

A traveling machine body having a control section for an operator to perform a traveling operation;
a hydraulic stepless transmission that changes the traveling power of the traveling body;
a speed change operation tool provided in the control unit for performing a speed change operation of the hydraulic continuously variable transmission;
an operation detection means for detecting an operation of the speed change operation tool;
an operating member for operating the hydraulic stepless transmission;
a motor for operating the operating member;
a control unit that shifts the hydraulic stepless transmission to a forward state, a neutral state, or a reverse state by controlling the drive of the motor according to the operation of the shift operation tool;
The control unit stores in advance, as an operation position of the operation member, a first operation position at which the stepless transmission can be operated from a forward side to a neutral state,
When the gear shift operation device is operated to shift the hydraulic continuously variable transmission to a neutral state while the traveling machine body is traveling forward, the control unit moves the operating member from the forward side to the first position. The stepless transmission is put in a neutral state by performing a forward stop operation by operating to the 1 operation position, and the hydraulic stepless transmission is put in the neutral state by the speed change operation tool while the traveling machine body is traveling backward. A reverse stop operation in which, when a shift operation is performed, the operation member is operated from the reverse side to the first operation position after passing through a predetermined third operation position that is preset to the forward side rather than the first operation position. a work vehicle configured to control the continuously variable transmission to a neutral state by A traveling machine body having a control section for an operator to perform a traveling operation;
a hydraulic stepless transmission that changes the traveling power of the traveling body;
a speed change operation tool provided in the control unit for performing a speed change operation of the hydraulic continuously variable transmission;
an operation detection means for detecting an operation of the speed change operation tool;
an operating member for operating the hydraulic stepless transmission;
a motor for operating the operating member;
a control unit that shifts the hydraulic stepless transmission to a forward state, a neutral state, or a reverse state by controlling the drive of the motor according to the operation of the shift operation tool;
The control unit has, as operating positions of the operating member, a first operating position at which the stepless transmission can be operated from the forward side to a neutral state, and a first operating position at which the stepless transmission can be shifted from the reverse side to the neutral state. operable second operation positions are stored in advance;
When the gear shift operation device is operated to shift the hydraulic continuously variable transmission to a neutral state while the traveling machine body is traveling forward, the control unit moves the operating member from the forward side to the first position. The stepless transmission is put in a neutral state by performing a forward stop operation by operating to the 1 operation position, and the hydraulic stepless transmission is put in the neutral state by the speed change operation tool while the traveling machine body is traveling backward. The work vehicle is configured to control the continuously variable transmission to a neutral state by performing a reverse stop operation in which the operation member is operated from the reverse side to the second operation position as it is when a gear shift operation is performed. a manual switching operation tool for manually switching the hydraulic continuously variable transmission to a neutral state via the operating member separately from the speed change operation tool;
a manual operation detection sensor for detecting an operation of the manual switching operation tool;
The manual switching operation tool is configured to be able to operate the operation member to the first operation position,
The control unit is configured to operate the operating member to stop the operating member on the reverse travel side when it is detected that the switching operation of the manual switching operation device that has been performed while the continuously variable transmission is in the reverse travel state is canceled. The work vehicle according to claim 1 or 2. The work vehicle according to claim 3, wherein the manual switching operation tool is a brake operation tool. A torque limiter type clutch is provided between the motor and the operating member,
The clutch includes a pawl clutch portion that idles around a support shaft driven by the motor, a meshing portion that faces the pawl clutch portion and rotates integrally with the support shaft, and a clutch portion that rotates along the rotation direction of the clutch portion and the meshing portion. and an urging member for urging the pawl clutch portion or the meshing portion. The power transmission is configured to disconnect,
When the brake operating device is manually operated, the clutch is within the range of the amount of deviation that occurs when the operating member is operated to the first operating position and to the second operating position by the inclined portion. The work vehicle according to claim 4, configured to fit The work vehicle according to claim 4 or 5, wherein the control unit is configured to drive the motor in a direction in which the operation member is operated when the stepping operation of the brake pedal is detected.

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