JP2014227015A - Work vehicle pto transmission apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To configure a PTO transmission apparatus with an infinite variable-speed transmission apparatus so as to change a rotation speed discretionarily.SOLUTION: A work vehicle 1 for use in transmitting power from an engine 3 to a travel-system transmission apparatus and a PTO-system transmission apparatus to enable driving includes: a variable-speed transmission apparatus 70 disposed between a PTO input shaft 55 receiving power transmitted from the engine 3 and a PTO shaft 66 outputting power externally; a PTO speed change lever 9 constituting output rotation speed setup means for setting a rotation speed of the PTO shaft 66; a speed change actuator 74 for changing an output of the variable-speed transmission apparatus 70; output rotation speed detection means 82 for detecting a rotation speed of the PTO shaft 66; and a control device 80 that is enabled to change a rotation speed of the PTO shaft 66 independently of the rotation speed of the PTO input shaft 55.

Description

  The present invention relates to a PTO transmission apparatus for shifting a rotational speed of a PTO shaft to an input rotational speed from an engine so as to obtain a desired rotational speed in a work vehicle including a power take-off shaft (hereinafter referred to as a PTO shaft).

  2. Description of the Related Art Conventionally, in a work vehicle such as a tractor, power from an engine is generally transmitted to a PTO shaft via a stepped PTO transmission. However, at the start of the operation, the speed is rapidly increased to the set rotational speed simultaneously with the “engagement” operation of the main clutch, so the shock is great and the durability is inferior. Therefore, the mechanical power transmission path and the path through the hydraulic continuously variable transmission are arranged in parallel so that the power from the engine can be transmitted to the PTO shaft, and the hydraulic continuously variable transmission is installed at the start of driving. When power is transmitted via a predetermined rotational speed, power is transmitted via a mechanical power transmission path (see Patent Document 1).

JP-A-6-1155

However, when the rotational speed is higher than the set rotational speed, the engine is rotated at the set gear position. Therefore, even if the efficiency is improved, if the engine rotational speed varies, the rotational speed of the PTO shaft also varies. For example, when mowing with mower, when the running speed changes, the engine speed also changes, and the PTO shaft speed also changes, resulting in unevenness in the finish after cutting.
The present invention intends to configure the PTO transmission as a continuously variable transmission so that it can be changed to an arbitrary rotational speed.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
That is, according to the first aspect of the present invention, in a work vehicle that can be driven by transmitting power from the engine to the traveling transmission and the PTO transmission, a PTO input shaft to which the power from the engine is transmitted and the outside A continuously variable transmission interposed between the PTO shaft for outputting power, output rotational speed setting means for setting the rotational speed of the PTO shaft, a transmission actuator for changing the output of the continuously variable transmission, and the PTO An output rotation speed detecting means for detecting the rotation speed of the shaft and a control device are provided, and the control device can change the rotation speed of the PTO shaft independently of the rotation of the PTO input shaft.

  According to a second aspect of the present invention, a travel speed detecting means for detecting a travel speed is connected to the control device, and the control device keeps the rotational speed of the PTO shaft constant with respect to a change in the travel speed. .

  According to a third aspect of the present invention, a travel speed detecting means for detecting a travel speed and a travel speed setting means are connected to the control device, and the control device keeps the travel speed constant and allows the rotational speed of the PTO shaft to be arbitrarily set. The speed can be changed.

  According to a fourth aspect of the present invention, a travel speed detecting means for detecting a travel speed and a travel speed setting means are connected to the control device, and the control device changes the rotational speed of the PTO shaft in accordance with a change in the travel speed. It is a thing.

As effects of the present invention, the following effects can be obtained.
Even if the input rotation from the engine fluctuates, the rotation speed of the PTO shaft can be kept constant or changed to an arbitrary rotation speed. The rotation speed of the PTO shaft can be changed arbitrarily according to the work. And work accuracy can be improved.

The side view which showed the whole structure of the working vehicle provided with the PTO transmission which concerns on embodiment of this invention. The skeleton figure of a transmission. The skeleton figure and control block diagram of a PTO transmission.

  First, the whole structure which used the work vehicle 1 concerning this invention as the tractor is demonstrated from FIG. The direction of arrow F is the front.

  The work vehicle 1 is equipped with a plowing device such as a rotary and a work machine such as a loader to perform various farm work and civil engineering work. The work vehicle 1 mainly includes a body frame 2, an engine 3, a transmission case 4, front wheels 5 and 5, rear wheels 6 and 6, a cabin 7, and the like.

The body frame 2 is a main structure of the work vehicle 1. The machine body frame 2 is composed of a plurality of plate materials or the like with the longitudinal direction as the front-rear direction.
The engine 3 is mounted on the front part of the body frame 2 and is covered with a bonnet 8. The transmission case 4 houses a traveling system and a PTO transmission, shifts the power generated by the engine 3, and transmits the power to the front wheels 5, the rear wheels 6, and the PTO shaft 66. The mission case 4 is provided in the rear part of the body frame 2.

  The front wheels 5 and 5 are supported on the front portion of the body frame 2 via a front axle case. The rear wheels 6 and 6 are supported via rear axle cases arranged on the left and right sides of the transmission case 4 at the rear of the body frame 2.

Operation members such as a steering handle 14, a seat 15, a main transmission lever 17, a lift lever, a PTO transmission lever 9 serving as an output rotation speed setting means, a setting dial, and a mode switching means 87 are disposed at the rear of the bonnet 8 covering the engine 3. And is covered by the cabin 7. The main speed change lever 17 sets the traveling speed, and the set value is detected by a shift position detecting means 86 provided at the rotation base of the main speed change lever 17 and input to the control device 80 (see FIG. 2). .
The PTO speed change lever 9 sets the rotation speed of the PTO shaft, and the set value is detected by the set PTO speed detection means 83 provided at the rotation base of the PTO speed change lever 9 and is input to the control device 80. (See FIG. 3).

  Next, the configuration of the transmission device housed in the mission case 4 will be described with reference to FIG. The transmission includes a traveling transmission and a PTO transmission. The traveling system transmission mainly includes a hydraulic continuously variable transmission (hereinafter simply referred to as “HST”) 10, a planetary gear mechanism 20, a main transmission mechanism 30, an auxiliary transmission mechanism 40, a differential mechanism 50, and the like. Includes a PTO transmission mechanism 60. However, the traveling transmission is not limited to a hydraulic continuously variable transmission or an HMT transmission that uses a planetary gear mechanism, but a hydraulic continuously variable transmission that does not use a planetary gear mechanism, a belt-type continuously variable transmission, Also, it can be constituted by a hydraulic clutch transmission, a gear sliding selection transmission, or the like. Moreover, it can also be set as the structure which provides a forward / reverse switching mechanism separately.

  The HST 10 mainly includes a hydraulic pump 11, a hydraulic motor 12, and the like. The hydraulic pump 11 is composed of a variable displacement hydraulic pump configured to change its capacity. The hydraulic pump 11 is driven by a drive shaft 13 that is rotationally driven by the power generated by the engine 3 and pumps hydraulic oil. The hydraulic pump 11 includes a movable swash plate 11a for changing its capacity. By changing the inclination angle of the movable swash plate 11a, the flow rate of the hydraulic oil pumped from the hydraulic pump 11 can be changed. The movable swash plate 11 a is tilted by the traveling speed change actuator 16 so that the rotation speed and rotation direction of the output shaft 12 a of the hydraulic motor 12 can be changed. The traveling speed change actuator 16 is connected to the control device 80.

  The hydraulic motor 12 is composed of a constant capacity type hydraulic motor whose capacity cannot be changed. The hydraulic motor 12 is driven in response to the hydraulic oil fed by the hydraulic pump 11. The hydraulic motor 12 includes an output shaft 12a, and the driving force of the hydraulic motor 12 is output via the output shaft 12a.

  The HST 10 configured as described above is driven by the power from the engine 3 being transmitted to the drive shaft 13 of the hydraulic pump 11, and the hydraulic oil is supplied to the hydraulic motor 12 in an amount corresponding to the inclination angle of the movable swash plate 11 a. Pump. The hydraulic motor 12 is driven by hydraulic fluid fed by the hydraulic pump 11 and outputs power from the output shaft 12a. In this way, the power of the drive shaft 13 can be shifted and transmitted to the output shaft 12a, and the gear ratio can be changed by changing the inclination angle of the movable swash plate 11a. When the travel speed is set with the main speed change lever 17 (or speed setting dial or the like), the control device 80 compares the set value with the detected value from the travel speed detecting means 85, and the travel speed change actuator 16 moves the movable swash plate. 11a is tilted so that it can run at a set speed.

  In this embodiment, the hydraulic pump 11 is a variable displacement type. However, the present invention is not limited to this, and a configuration in which the hydraulic motor 12 is a variable displacement type, or both the hydraulic pump 11 and the hydraulic motor 12 are variable displacement types. It is also possible to adopt a configuration with a mold. The HST 10 may be of a type in which a pump plunger and a motor plunger are provided in one cylinder block, and the hydraulic pump and the hydraulic motor are integrally formed on the same axis. Further, the arrangement position is not limited.

  A third transmission shaft 32 is connected to the rear of the output shaft 12a on the same axis as the output shaft 12a so as not to rotate relative to the output shaft 12a. A fourth transmission gear 33 is fixed to the rear end portion of the third transmission shaft 32, and the fourth transmission gear 33 meshes with a gear portion 27a of an internal gear 27 of the planetary gear mechanism 20 described later.

  The planetary gear mechanism 20 is disposed behind the HST 10. The planetary gear mechanism 20 mainly includes a first transmission shaft 22, a first transmission gear 23, a second transmission shaft 24, a sun gear 25, a second transmission gear 26, an internal gear 27, a third transmission gear 28, a carrier 29, and a planetary gear 21.・ 21 ... etc.

  The first transmission shaft 22 is disposed on the same axis line behind the drive shaft 13 and is connected to the drive shaft 13 so as not to be relatively rotatable. A first transmission gear 23 is fixed on the front portion of the first transmission shaft 22, and a second transmission shaft 24 is disposed in parallel with the first transmission shaft 22.

  A sun gear 25 is fitted on the front end portion of the second transmission shaft 24 so as to be relatively rotatable, a second transmission gear 26 is fixed on the shaft portion of the sun gear 25, and the second transmission gear 26 meshes with the first transmission gear 23. To do. The internal gear 27 is fitted on the shaft portion of the sun gear 25 and behind the second transmission gear 26 so as to be rotatable relative to the sun gear 25.

  A third transmission gear 28 is fitted on the second transmission shaft 24 and behind the sun gear 25 so as to be rotatable relative to the second transmission shaft 24. The carrier 29 is fitted on the second transmission shaft 24 and in front of the third transmission gear 28 so as to be rotatable relative to the second transmission shaft 24.

  The planetary gears 21, 21,... Are rotatably supported on the front end portion of the carrier 29 via planetary shafts. A plurality of planetary gears 21, 21... Are provided on a concentric circle with the second transmission shaft 24 as the center. The planetary gears 21, 21... Mesh with the internal gear 27 and the sun gear 25. Planetary gear 21 also meshes with third transmission gear 28.

The main transmission mechanism 30 includes a travel mode switching clutch 31, a fifth transmission gear 34, a reverse gear 35, a sixth transmission gear 36, a forward / reverse switching clutch 37, and the like.
The travel mode switching clutch 31 is constituted by a hydraulic clutch, and includes a low speed clutch 31a and a high speed clutch 31b. The high speed clutch 31b connects and disconnects power between the third transmission gear 28 and the second transmission shaft 24, The low speed clutch 31 a connects and disconnects the power between the carrier 29 and the second transmission shaft 24. The low-speed clutch 31a and the high-speed clutch 31b are connected and disconnected by switching the solenoid valves 88 and 89 to switch the oil supply direction of the pressure oil. The electromagnetic valves 88 and 89 are connected to the control device 80.

  The fifth transmission gear 34 is provided at the rear end of the first transmission shaft 22 so as to be rotatable relative to the first transmission shaft 22. Gear portions are formed at the front end portion and the rear end portion of the fifth transmission gear 34, and are engaged with the carrier 29 and the sixth transmission gear 36.

  The reverse gear 35 is provided on the second transmission shaft 24 and behind the carrier 29 so as to be rotatable relative to the second transmission shaft 24. The rear end portion of the reverse gear 35 is meshed with the sixth transmission gear 36.

  The forward / reverse switching clutch 37 is constituted by a hydraulic clutch and is connected / disconnected by switching of the electromagnetic valve 38. The electromagnetic valve 38 is connected to the control device 80. It is provided in front of the reverse gear 35 and switches between a state where the reverse gear 35 and the second transmission shaft 24 are connected so as not to be relatively rotatable and a state where the connection is released so as to be relatively rotatable. is there.

The operation mode of the planetary gear mechanism 20 configured as described above will be described.
The power generated by the engine 3 is transmitted to the first transmission gear 23 via the drive shaft 13. The power transmitted to the first transmission gear 23 is transmitted to the planetary gears 21, 21... Via the second transmission gear 26 and the sun gear 25.
On the other hand, the power generated by the engine 3 and shifted in the HST 10 is transmitted to the third transmission shaft 32 via the output shaft 12 a of the hydraulic motor 12. The power transmitted to the third transmission shaft 32 is transmitted to the planetary gears 21, 21... Via the fourth transmission gear 33 and the internal gear 27.

The planetary gears 21, 21... Revolve around the second transmission shaft 24 while rotating by the power from the two paths transmitted to the planetary gears 21, 21. Power is transmitted to the third transmission gear 28 by the rotation of the planetary gears 21. Power is transmitted to the carrier 29 by the revolution of the planetary gears 21.
When the high-speed clutch 31 b of the travel mode switching clutch 31 is operated and the third transmission gear 28 and the second transmission shaft 24 are connected, the power of the third transmission gear 28 is transmitted to the second transmission shaft 24. When the low speed clutch 31 a of the travel mode switching clutch 31 is operated and the carrier 29 and the second transmission shaft 24 are connected, the power of the carrier 29 is transmitted to the second transmission shaft 24.

  The power of the carrier 29 is transmitted to the reverse gear 35 via the fifth transmission gear 34 and the sixth transmission gear 36. In a state where the travel mode switching clutch 31 is disconnected from the third transmission gear 28 and the carrier 29 and the second transmission shaft 24, the reverse rotation gear 35 and the second transmission shaft 24 are connected by the forward / reverse switching clutch 37. In this case, the power of the reverse gear 35 is transmitted to the second transmission shaft 24. In this case, the second transmission shaft 24 rotates in the direction opposite to the rotation direction when the mode switching clutch 31 connects the third transmission gear 28 or the carrier 29 and the second transmission shaft 24.

  As described above, the power generated by the engine 3 and the power generated by the engine 3 and shifted in the HST 10 are combined in the planetary gear mechanism 20 and the combined power (hereinafter simply referred to as “combined power”). Is output from the second transmission shaft 24.

  The subtransmission mechanism 40 can switch the gear ratio to a low speed or a high speed, or to a neutral state where transmission of power is cut off. The power shifted in the auxiliary transmission mechanism 40 is transmitted to the differential mechanism 50 via the auxiliary transmission output shaft 42. The rotational speed of the auxiliary transmission output shaft 42 is detected by the traveling speed detecting means 85 as the traveling speed. The detection value of the traveling speed detection means 85 is input to the control device 80. However, the auxiliary transmission mechanism 40 is not limited to the gear sliding selection type, and may be a hydraulic clutch type or the like. Further, the detection of the traveling speed is not limited to the rotation speed of the auxiliary transmission output shaft 42 but can be detected by an axle or the like.

  The differential mechanism 50 distributes the power transmitted from the auxiliary transmission mechanism 40 to the left and right, and transmits the power to the left and right rear wheels 6 and 6, respectively. In addition, description is abbreviate | omitted about the structure for the power transmission from the engine 3 to the front wheels 5 * 5 in the work vehicle 1 which concerns on this embodiment.

  A PTO input shaft 55 is disposed on the same axis at the rear end of the first transmission shaft 22 to which power from the engine 3 is transmitted, and a PTO transmission mechanism 60 is provided at the rear of the PTO input shaft 55. The PTO transmission mechanism 60 will be described with reference to FIG.

The PTO transmission mechanism 60 includes a PTO clutch 61, a PTO transmission gear 62, a PTO input gear 63, a continuously variable transmission 70, a reduction gear mechanism 65, a PTO shaft 66, and the like.
The PTO clutch 61 is disposed between the PTO input shaft 55 and the PTO clutch output shaft 56. The PTO clutch 61 is constituted by a hydraulic clutch, is connected to the control device 80, and is connected / disconnected by operating the PTO speed change lever 9 or the work mode switching means 87 provided in the cabin 7. The rotational speed of the PTO input shaft 55 is detected by the input rotational speed detection means 81. The input rotation speed detection means 81 is connected to the control device 80. The rotational speed of the PTO input shaft 55 may be configured to detect the engine output rotational speed.

  A PTO transmission gear 62 is fixed to the rear portion of the PTO clutch output shaft 56, and the PTO transmission gear 62 is meshed with the PTO input gear 63. The speed is increased by the PTO transmission gear 62 and the PTO input gear 63. The PTO input gear 63 is fixed on the front portion of the PTO transmission input shaft 64 of the continuously variable transmission 70. The PTO speed change input shaft 64 is installed in parallel with the PTO input shaft 55 and the PTO shaft 66.

The continuously variable transmission 70 includes a PTO transmission input shaft 64, an input pulley 71, an output pulley 72, a belt 73, a transmission actuator 74, an urging member 75, and the like. The input pulley 71 and the output pulley 72 are composed of split pulleys that are divided into front and rear.
The input pulley 71 includes an input side fixed sheave 71 a and an input side movable sheave 71 b, and the input side fixed sheave 71 a is fixed to the rear portion of the PTO speed change input shaft 64. The input side movable sheave 71b is externally fitted on the PTO speed change input shaft 64 so as to be slidable in the axial direction and not to be relatively rotatable. The input side movable sheave 71 b is slidably driven in the axial direction by the speed change actuator 74. The speed change actuator 74 is connected to and controlled by the control device 80. The amount of movement of the input side movable sheave 71 b is detected by a pulley position detecting means 84, and the pulley position detecting means 84 is connected to the control device 80.

  The output pulley 72 includes an output side fixed sheave 72 a and an output side movable sheave 72 b, and the output side fixed sheave 72 a is fixed to the PTO speed change output shaft 76. The output-side movable sheave 72b is externally fitted on the PTO speed change output shaft 76 so as to be slidable in the axial direction and not relatively rotatable. The output side movable sheave 72b is urged by the urging member 75 so as to slide in the axial direction toward the output side fixed sheave 72a.

The belt 73 is wound around the input pulley 71 and the output pulley 72 so that power can be transmitted.
The speed change actuator 74 comprises a hydraulic cylinder and is connected to the input side movable sheave 71b. The hydraulic cylinder is expanded and contracted by switching the electromagnetic valve, and the input side movable sheave 71b can be slid to change the width with the input side fixed sheave 71a. The electromagnetic valve is connected to the control device 80 to control expansion and contraction of the hydraulic cylinder. However, the speed change actuator 74 is not limited to a hydraulic cylinder, and may be constituted by an electric cylinder, a motor, or the like.

  The urging member 75 is constituted by a spring and is fitted on the PTO speed change output shaft 76. However, the input side movable sheave 71b may be biased toward the input side fixed sheave 71a by the biasing member 75, and the output side movable sheave 72b may be slid in the axial direction by the speed change actuator 74.

  The control device 80 includes an input rotational speed detecting means 81 for detecting the rotational speed of the PTO input shaft 55, an output rotational speed detecting means 82 for detecting the rotational speed of the PTO shaft 66, and a PTO speed change lever 9 (PTO rotational speed setting). The setting PTO rotation speed detecting means 83 for detecting the shift position is connected. Thus, by changing the PTO speed change lever 9 (or PTO speed change dial), the continuously variable transmission device 70 can arbitrarily change the rotational speed of the PTO shaft 66.

  The PTO speed change output shaft 76 is connected to the PTO shaft 66 through a reduction gear mechanism 65. The reduction gear mechanism 65 includes a first reduction drive gear 91, a first reduction driven gear 92, a second reduction drive gear 93, a second reduction driven gear 94, and the like.

  The first reduction drive gear 91 is fixed on the rear portion of the PTO transmission output shaft 76 and meshed with the first reduction driven gear 92. The first reduction driven gear 92 is fixed to the reduction shaft 95, and a second reduction drive gear 93 is fixed to the rear portion of the reduction shaft 95 and meshed with the second reduction driven gear 94. The second reduction driven gear 94 is fixed on the PTO shaft 66. The first reduction driving gear 91 and the second reduction driving gear 93 are constituted by small-diameter gears, and the first reduction driven gear 92 and the second reduction driven gear 94 are constituted by large-diameter gears, and are decelerated in two stages. However, when the gear ratio of the continuously variable transmission 70 can be configured to be large, the reduction gear mechanism 65 can be omitted, and the number of reduction gears can be increased or decreased according to the work. .

In the above configuration, when working, the work mode is switched by the work mode switching means 87. The work mode switching means 87 is composed of, for example, a dial, and “working speed constant mode”, “running speed constant, working speed variable mode”, and “running speed tracking mode” are set as work modes.
When the work mode switching means 87 is set to the “constant work speed mode”, when the PTO shift lever 9 is operated to a position other than the neutral position, the PTO clutch 61 is turned “ON” and the rotational speed of the PTO shaft 66 is set to the PTO rotational speed setting means. The continuously variable transmission 70 is shifted so as to achieve the rotational speed set by the PTO shift lever 9.

  That is, the control device 80 compares the value detected by the output rotation speed detection means 82 with the set rotation speed by the set PTO rotation speed detection means 83, and when the rotation speed of the PTO shaft 66 is lower than the set rotation speed. Operates the speed change actuator 74, slides the input side movable sheave 71b toward the input side fixed sheave 71a, narrows the width of the input pulley 71, moves the winding position of the belt 73 to the outer diameter side, The rotational speed of the PTO shaft 66 is increased. On the other hand, when the rotational speed of the PTO shaft 66 is higher than the set rotational speed, the speed change actuator 74 is operated to slide the input side movable sheave 71b away from the input side fixed sheave 71a. , The winding position of the belt 73 is moved to the center side, and the rotational speed of the PTO shaft 66 is reduced. Further, when the rotational speed of the engine 3 fluctuates due to a load or the like, the continuously variable transmission 70 is operated similarly to the above, and the speed change actuator 74 is controlled so that the rotational speed of the PTO shaft 66 becomes the set rotational speed.

  In other words, even if the traveling speed changes due to a load or the like, or the traveling speed is increased or decreased, or the engine rotational speed changes, the rotational speed of the PTO shaft 66 is kept constant. Is possible. In other words, it is possible to change the traveling speed while keeping the rotational speed of the PTO shaft 66 constant. For example, when performing the cutting operation, the cutting efficiency is reduced when the rotational speed of the cutting blade is reduced. Therefore, even if the engine rotational speed is changed, the rotational speed of the PTO shaft 66 is kept constant. Even if the engine speed is decreased by increasing the traveling speed, the rotational speed of the PTO shaft 66 is kept constant.

  Further, when the work mode switching means 87 is set to the “running speed constant, work speed variable mode”, the work speed (the number of rotations of the PTO shaft 66) can be increased or decreased while keeping the running speed constant. That is, the control device 80 compares the speed set by the main shift lever 17 with the actual traveling speed sensed by the traveling speed detecting means 85, and if the actual traveling speed is slower than the set speed, operates the traveling transmission actuator 16. When the traveling speed is increased and the actual traveling speed is higher than the set speed, the traveling speed change actuator 16 is operated to reduce the traveling speed so that the set speed is reached. Then, the operator operates the PTO shift lever 9 to shift the continuously variable transmission 70 to a desired output rotational speed. For example, when you want to partially increase or decrease the amount of fertilization in fertilization work, or when you want to partially increase or decrease the sowing interval in sowing work, run at a constant traveling speed, The continuously variable transmission 70 is operated by the shift lever 9, and the fertilizing amount and the sowing interval can be arbitrarily changed.

Further, when the work mode switching means 87 is set to the “traveling speed tracking mode”, the rotational speed of the PTO shaft 66 can be changed in accordance with the change of the traveling speed. For example, in fertilizing work or control work, if you want to finish the work early by increasing the traveling speed, you must increase the working speed if you increase the traveling speed, but if you simply increase or decrease the traveling speed, Fertilizer application amount and spread amount will change. Therefore, when the travel speed is increased or decreased, the work speed is increased or decreased in proportion (proportional) to the speed. In addition, when the load increases in tillage work or the like, the traveling speed is reduced to reduce the load, but the work speed must also be reduced. Also in this case, the working speed is reduced in accordance with the traveling speed.
Specifically, the control device 80 detects the traveling speed by the traveling speed detecting means 85, detects the PTO shaft rotational speed (working speed) by the output rotational speed detecting means 82, and determines the rotational speed of the PTO shaft 66 as the traveling speed. In response to this change, the speed change actuator 74 is operated to shift the continuously variable transmission 70, and the rotational speed of the PTO shaft 66 is adjusted to the change in travel speed. That is, the control device 80 controls the speed change actuator 74 so that the increase / decrease rate of the traveling speed matches the increase / decrease rate of the rotational speed of the PTO shaft 66.

  The continuously variable transmission 70 is not limited to a belt type, and may be a traction type (a toroidal type, a cone roller type, or the like). It is also possible to use a hydraulic continuously variable transmission.

  As described above, in the work vehicle 1 that can drive by transmitting the power from the engine 3 to the traveling transmission and the PTO transmission, the PTO input shaft 55 to which the power from the engine 3 is transmitted, and the external A continuously variable transmission 70 interposed between the PTO shaft 66 for outputting power to the PTO shaft 66, a PTO transmission lever 9 serving as an output rotational speed setting means for setting the rotational speed of the PTO shaft 66, and the continuously variable transmission. 70, a speed change actuator 74 for changing the output of the output 70, an output speed detection means 82 for detecting the speed of the PTO shaft 66, and a control device 80. The control device 80 responds to the rotation of the PTO input shaft 55. Since the rotational speed of the PTO shaft 66 can be changed independently, the rotational speed of the PTO shaft 66 can be changed independently with respect to fluctuations in the engine rotational speed. Therefore, since the rotation speed of the PTO shaft 66 can be arbitrarily changed, the work rotation speed can be easily changed according to the work mode, and work efficiency can be improved.

  Further, since the traveling speed detecting means 85 for detecting the traveling speed is connected to the control device 80, and the control device 80 keeps the rotation speed of the PTO shaft 66 constant with respect to the change of the traveling speed, Even when the traveling speed changes, the working speed can be kept constant and the work performance can be improved in the working place with unevenness or the lawn mowing work while turning.

  In addition, a travel speed detecting means 85 for detecting the travel speed and a travel speed setting means are connected to the control device 80, and the control device 80 keeps the travel speed constant and allows the rotational speed of the PTO shaft 66 to be arbitrarily set. Since the speed can be changed, when working at a constant speed, the work speed can be easily changed to an arbitrary speed, and the amount of fertilizer applied, the amount of sprayed medicine, the amount of water spray, etc. are partially increased or decreased. can do.

  Further, a traveling speed detecting means 85 for detecting the traveling speed and a traveling speed setting means are connected to the control device 80, and the control device 80 changes the rotational speed of the PTO shaft 66 in accordance with a change in the traveling speed. Therefore, even when the traveling speed increases or decreases during the harvesting operation, the cutting operation, or the like, the operation speed can be followed and the work performance can be improved. In addition, when the load increases, the traveling speed is reduced, and the working speed is reduced according to the reduction. Therefore, the work can be performed at the optimum engine speed, and the fuel consumption can be suppressed.

DESCRIPTION OF SYMBOLS 1 Work vehicle 3 Engine 9 PTO speed change lever 55 PTO input shaft 66 PTO shaft 70 Continuously variable transmission device 74 Transmission actuator 80 Control device 82 Output rotation speed detection means 85 Travel speed detection means

Claims (4)

  In a work vehicle that can be driven by transmitting power from an engine to a traveling transmission and a PTO transmission, a PTO input shaft that transmits the power from the engine and a PTO shaft that outputs the power to the outside A continuously variable transmission interposed therebetween, output rotational speed setting means for setting the rotational speed of the PTO shaft, a transmission actuator for changing the output of the continuously variable transmission, and an output for detecting the rotational speed of the PTO shaft A PTO transmission for a work vehicle, comprising: a rotation speed detecting means; and a control device, wherein the control device can change the rotation speed of the PTO shaft independently of the rotation of the PTO input shaft.   The travel speed detecting means for detecting the travel speed is connected to the control device, and the control device keeps the rotational speed of the PTO shaft constant with respect to a change in the travel speed. A PTO transmission for a work vehicle as described.   A travel speed detecting means for detecting the travel speed and a travel speed setting means are connected to the control device, and the control device can keep the travel speed constant and change the rotational speed of the PTO shaft to an arbitrary rotational speed. The PTO transmission device for a work vehicle according to claim 1, wherein the PTO transmission device is a work vehicle.   A travel speed detecting means for detecting a travel speed and a travel speed setting means are connected to the control device, and the control device changes the rotational speed of the PTO shaft in accordance with a change in the travel speed. The PTO transmission for a work vehicle according to claim 1.

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