JP2007008320A - Gear shift device in working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a user of an agricultural tractor or the like is supposed to be provided with an HST as a traveling transmission and to select a method of operating the car body with a single lever or supposed to be provided with a gear-type transmission and to select a method of operating the car body with a shuttle-type advance and retreat switching lever and a gear shifting lever in accordance with a main work, and that, for example, a tractor equipped with the HST is required to adjust a gear position for every switch of forward or retreat during loader operation for repeating forward and retreat or towing operation in an agricultural field, which impairs operability. <P>SOLUTION: The tractor comprises the HST as a traveling transmission and an electric motor 4 for operating a trunnion shaft which adjusts output rotations of the HST. The tractor further comprises forward and retreat switches 5a and 5b for detecting the shuttle-type forward and retreat switching lever and operation positions of the lever and a lever position sensor 6s which detects the gear shifting lever for adjusting speed of a car and operation positions of the lever. A controller C drives a motor 4 in accordance with a detection value of each sensor 5a, 5b or 6s. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gear shifting operation device for work vehicles for agriculture, construction, and transportation having a hydrostatic continuously variable transmission (HST) and a belt type continuously variable transmission.

2. Description of the Related Art Conventionally, agricultural tractors are known to have an HST as a traveling system transmission device and operate a single shift lever, a so-called HST lever, to move the vehicle forward and backward and change the vehicle speed.
The agricultural tractor is equipped with a gear-type forward / reverse switching device and a gear-type transmission, and the vehicle's forward / backward movement and vehicle speed are operated separately by operating the shuttle-operated forward / reverse switching lever and the shift lever. The configuration is also known.

As described above, the tractor equipped with the HST is suitable for lawn mowing work where fine adjustment of the vehicle speed is mainly required, and the tractor equipped with the gear-type transmission is mainly used for high load work that repeats forward and backward. For example, it is suitable for loader work or towing work on a farm field.
JP2003-134903

  The tractor user is equipped with the HST according to the main work and is designed to operate the vehicle body with a single lever or with a gear-type transmission, and the vehicle body is moved with the forward / reverse switching lever and the transmission lever. Since the specifications to be operated are selected, when performing lawn mowing work other than the main work, for example, with a tractor equipped with a gear-type transmission, the vehicle speed cannot be finely adjusted and the operability is poor, and the HST is provided. In the tractor, it is necessary to adjust the shift position every time the forward / backward movement is switched in the loader work or the towing work in the field where the forward / backward movement is repeated.

In view of the above problems, the present invention is configured as follows.
That is, according to the first aspect of the present invention, the continuously variable transmission (3) for shifting the rotation of the engine (E) and transmitting it to the traveling device (1F, 1R) and the output rotation of the continuously variable transmission (3) are adjusted. A forward / reverse switching lever (5) for selecting a forward / backward traveling direction and a forward / backward operation detection sensor (5a) for detecting an operation position of the lever (5). , 5b), a shift lever (6) for adjusting the vehicle speed of the vehicle, and a shift position sensor (6s) for detecting the operation position of the lever (6), the detected values of the sensors (5a, 5b, 6s) Accordingly, a shift operation device for a work vehicle provided with a controller (C) for driving the actuator (4) according to the above.
(Operation of claim 1)
In the work vehicle according to claim 1 configured as described above, the traveling direction of the vehicle is set by operating the forward / reverse switching lever (5), and the speed of the vehicle is set by operating the shift lever (6). The The control unit (C) drives the actuator (4) according to the operation position of the levers (5, 6), and the vehicle travels.

According to the invention of claim 2, the vehicle includes a main clutch (7) for turning on and off the rotational power transmitted from the engine (E) to the travel device (1F, 1R) and a clutch for operating the main clutch (7). A pedal (9) is provided, the shift lever (6) is configured in a linear shift form, the operating position at one end of the lever (6) is set to the highest speed position, and the operating position at the other end is set to the slow speed position. The shift operation device for a work vehicle according to claim 1, wherein the shift operation device is a work vehicle.
(Operation of claim 2)
In the work vehicle according to claim 2 configured as described above, by operating the forward / reverse switching lever (5), the traveling direction of the vehicle is set, and at the same time when the clutch pedal (9) is depressed and released, the engine (E) Is transmitted to the traveling devices (1F, 1R) to start the vehicle.

  As a result, according to the first aspect of the invention, the vehicle speed can be adjusted steplessly with the speed change lever (6) as usual in operations requiring fine vehicle speed adjustment. Since the forward / reverse switching operation can be performed by the forward / reverse switching lever (5) as in the case of the vehicle having the transmission, the operability is good with both forms of work.

  In the second aspect of the invention, since one end of the speed change lever (6) is set to the slow speed position, the vehicle speed is adjusted by the speed change lever (6) and the traveling direction is changed by the forward / reverse switching lever (5). Since the start and stop of the vehicle is operated by the clutch pedal (9), the roles of the respective operation members are divided, and the operability is better than the configuration in which the stop position is set to the shift lever, for example. .

Hereinafter, based on the drawings, an embodiment in which the present invention is mounted on an agricultural tractor T serving as a work vehicle will be described.
First, the configuration of the tractor T will be described.

  As shown in FIG. 2, the tractor T includes an engine E inside the bonnet 11, and the rotational power of the engine E is used as a traveling device via various transmission devices in the transmission case 12, or the front wheels 1 R or the front wheels 1 F. , 1R is transmitted to travel.

  A tractor T has a cylinder case 15 that houses a hydraulic cylinder 13 for raising and lowering the work implement. The lift arms 14 on both sides of the case are rotated up and down by the expansion and contraction of the piston of the cylinder 13 via a three-point link mechanism. The various working machines are lifted and lowered. Further, a lift arm angle sensor 14s is provided at the base of the lift arm 14 as a sensor for detecting the height of the work implement R, and the detection of the lever position sensor 18s of the work implement lift lever 18 base provided on the side of the cockpit 17 is provided. The piston of the hydraulic cylinder 13 for raising / lowering the work implement is driven so that the angles coincide.

  Further, a steering handle 19 for steering the front wheel 1F to the left and right is provided in front of the cockpit 17 of the tractor T, and a so-called shuttle type forward / reverse switching lever 5 for switching the vehicle forward / backward is provided below the steering handle 19 so as to be rotatable forward and backward. It has become. A forward switch 5a and a reverse switch 5b are provided at the rotation base of the forward / reverse switching lever 5 as sensors for detecting the forward / reverse operation of the operator, and a lever position operation for forcibly moving the operating position of the lever 5 is provided. The electric motor 28 is provided, and these signal lines are connected to the controller C below the cockpit 17. Further, in front of the steering handle 19, a liquid crystal monitor serving as a notification means, and a meter panel 25 having a buzzer 25b are provided.

  Also, below the steering handle 19, there are provided a clutch pedal 9 for intermittently operating the main clutch 7, and left and right brake pedals 8L, 8R for independently braking the brake devices 24L, 24R of the left and right rear wheels 1R, 1R, Brake pedal depression operation detection switches 8Ls and 8Rs for detecting the depression operation are provided at the rotation bases of the left and right brake pedals 8L (8R).

  Further, on the side of the cockpit 17 of the tractor T, a work implement lifting lever 18 for adjusting the height of the work implement R, and an HST lever (main shift lever) for adjusting the output rotation speed of the HST 3 serving as a main transmission. 6. A sub-transmission lever 27 for switching a shift position of a sub-transmission device 31 to be described later is provided. Further, as shown in FIG. 3, the HST lever 6 is configured in a so-called linear shift form in which the HST lever 6 is rotated back and forth on the left side of the cockpit 17. (L speed) is set at a position where the vehicle speed is about 0.3 km / h, assuming a very low speed assuming ultra low speed work, and the rear end operation position is also the highest speed position at L speed, about 0.5 km / h. The vehicle speed is set to the position.

Next, the power transmission path of the tractor T will be described with reference to FIG.
The rotational power of the engine E is turned on and off by the main clutch 7, and travel system power is supplied via the engine output shaft via the HST 3, which is the main transmission, the gear-type auxiliary transmission 31, and the rear wheel differential mechanism 32. The rotation is transmitted to the left and right rear wheels 1R and 1R, and the rotation output from the auxiliary transmission 31 is transmitted to the left and right front wheels 1F and 1F via the front wheel drive shaft 33 and the front wheel differential mechanism 34.

  The HST 3 includes a hydraulic pump 3P and a hydraulic motor 3M, and the output shaft of the hydraulic motor 3M is supplied via a hydraulic flow in which the rotational power transmitted from the power input shaft 3i of the hydraulic pump 3P is filled in a closed circuit. 3o, and the tilt angle of the swash plate inside the pump 3P is changed to the rotational position of the trunnion shaft 3a, and the rotational direction and rotational speed of the output shaft 3o of the motor 3M, that is, the forward and backward travel of the tractor T and the vehicle speed are determined. The configuration is changed. The transmission case 12 in the vicinity of the trunnion shaft 3a includes a trunnion shaft operating electric motor 4 that forcibly rotates the coaxial 3a.

  The auxiliary transmission 31 is a constant mesh gear type transmission, and operates the shifter and the slide gear by operating the auxiliary transmission lever 27 on the side of the cockpit 17 in the front-rear direction to operate the L, M, and H speeds. In this configuration, one of the three gears is selected.

  4 denotes a so-called front wheel speed increasing device having a constant speed clutch 38a that outputs the input rotation at the same speed and a speed increasing clutch 38b that outputs the input speed at the double speed. The driving speed of the front wheel 1F is increased from the normal speed to the double speed together with the brake of the rear wheel inside the turn by the operation from. The front wheel speed increasing device 38 has an electromagnetic pickup type vehicle speed sensor 45 on the front wheel side power transmission shaft.

Next, the hydraulic configuration of the tractor T will be described with reference to FIG.
The tractor T is provided with a first hydraulic pump P1 and a second hydraulic pump P2 that are driven by the rotation of the engine E, and the first hydraulic pump P1 sucks up oil from the transmission case 12 that also serves as a hydraulic oil tank. Is sent to the power steering circuit 40, and the surplus oil is sent to the closed circuit of the HST 3 through the oil cooler 41 and the filter 42 in detail as charge oil. The second hydraulic pump P <b> 2 is configured to suck up oil from the transmission case 12 and send pressure oil to the working machine lifting / lowering hydraulic cylinder 13 via the working machine lifting / lowering switching control valve 43.

Next, a control system for the tractor T will be described with reference to FIGS. 1, 6, and 7.
The controller C serving as the control unit of the tractor T includes a CPU that processes various types of information, an EEPROM that stores a control program, a RAM that temporarily stores sensor information and setting device information, and the like.

  The input part of the controller C includes a forward switch 5a for detecting the lever position of the forward / reverse switching lever 5, a reverse switch 5b, a lever position sensor 6s for detecting a change position of the HST lever 6, a left brake pedal depression switch 8Ls, A brake pedal depression switch 8Rs, a vehicle speed sensor 45, a front wheel turning angle sensor 1Fs for detecting a turning operation of the vehicle, a lever position sensor 18s at the base of the work lifting lever 18 and a lift arm angle sensor 14s are connected.

  The output part of the controller C includes the trunnion shaft operating electric motor 4, the forward / reverse switching lever operating electric motor 28, the liquid crystal monitor 25a, the alarm buzzer 25b, and the solenoids 43a and 43b of the work machine ascending / descending control valve 43. Are connected.

In the tractor T configured as described above, the speed change control shown in FIG.
First, when the power supply system of the tractor T is turned on, the states of various sensors and setting devices are read, and it is first determined whether or not the forward switch 5a or the reverse switch 5b is in an ON state, that is, the forward / reverse switching lever 5 Is operated to the forward position or the reverse position. When this determination is YES, the trunnion shaft operating electric motor 4 is energized so that the operation angle of the HST lever 6 and the set angle of the trunnion shaft 3a coincide.

  Specifically, as shown in FIG. 7, as the tilt angle of the HST lever 6 increases, the angle of the trunnion shaft 3 a also changes in proportion. Further, the HST lever 6 is set so that the set vehicle speed during the reverse operation at the same lever operation angle is lower than the set vehicle speed during the forward operation.

  When the determination is NO, that is, when both the forward switch 5a and the reverse switch 5b are OFF, the set angle of the trunnion shaft 3a is set to the forward slow speed position, approximately 0.3 km regardless of the position of the HST lever 6. It is configured to wait at a position where the vehicle speed becomes / h. Accordingly, the tractor T is accelerated as smoothly as possible when the forward / reverse switching lever 5 is operated to the forward position and the vehicle speed is increased to the position corresponding to the operation position of the HST lever 6 by the trunnion shaft operating electric motor 4. Can do.

  When the reverse switch 5b is turned on to reverse the tractor T, the vehicle speed is immediately set to 0 by the controller, and the vehicle speed is gradually increased. To completely stop the tractor T, the left and right brake pedals 8L and 8R are depressed or the clutch pedal 23 is depressed.

  Further, the tractor T always detects the depression state of the left and right brake pedals 8L and 8R during traveling. When the depression state of both the pedals 8L and 8R is turned on, it is assumed that the tractor T is stopped, and the vehicle speed sensor 45 The trunnion shaft operating electric motor 4 is energized so that the detected value becomes 0, and at the same time, the forward / reverse switching lever operating electric motor 28 is energized to move the lever 5 to the neutral position.

  As a result, the braking operation of the brake pedals 8L and 8R and the output rotational speed of the HST 3 are reduced, so that the tractor T can be quickly stopped. Further, since the position of the forward / reverse switching lever 5 moves to the neutral position, for example, the forward / reverse switching lever position is maintained at the forward position, and the deviation between the position of the lever 5 and the trunnion shaft 3a is canceled by a predetermined operation. Compared with the configuration, the operability when starting again is better.

  The controller C executes turning control when the detected value of the front wheel turning angle sensor 1Fs exceeds a predetermined angle. Specifically, the controller C decelerates the vehicle speed by a certain rate by the electric motor for operation of the trunnion shaft, and sends it to each control valve. By energizing, the lift arm is lifted and rotated to drive the front wheel 1F at a higher speed, and the rear wheel inside the turn is braked.

  In the tractor T configured as described above, the vehicle speed can be adjusted steplessly with the HST lever 6 and the vehicle can be moved forward and backward as usual in the work that requires fine adjustment of the vehicle speed even if the specification includes the HST3. In the work, since the forward / reverse switching operation can be performed by the forward / reverse switching lever 5 as in the case of the vehicle having the gear type transmission, the operability is good with both forms of work.

  In addition, the HST lever is configured as a linear shift type, and the operation position at one end is set to the highest speed position and the operation position at the other end is set to the slow speed position. In order to select the traveling direction with the switching lever 5 and to operate the start and stop of the vehicle with the clutch pedal 9, the role of each operation member is divided, for example, compared with a configuration in which a stop position is set on the HST lever. Good operability.

  As another form of the above-described form, instead of the configuration in which the position of the forward / reverse switching lever 5 is moved to the neutral position when the left and right brake pedals 8L and 8R are depressed, the HST lever 6 is forced to move the lever. An actuator to be operated may be provided, and the lever may be moved to the lowest speed position when the brake is operated.

  The relationship between the operating angle of the HST lever 6 and the setting angle of the trunnion shaft 3a may be proportional to a quadratic curve as shown in FIG. As a result, the vehicle speed can be set with a small speed increase rate in the low vehicle speed range, and a rapid speed change can be performed with a large speed increase rate in the high speed range.

The block diagram which shows the connection state of a controller. The whole tractor side view. The top view which shows the operation position of an HST lever. The transmission mechanism diagram of a tractor. 1 is a partial hydraulic circuit diagram of a tractor. The flowchart which shows the outline | summary of transmission control. The figure which shows the relationship between a transmission lever and a vehicle speed (1). Diagram showing the relationship between the speed change lever and vehicle speed (2)

Explanation of symbols

C controller (control unit)
E engine T tractor 1F front wheel 1R rear wheel 3 HST
4. Electric motor (actuator) for trunnion shaft operation
5 Forward / reverse switching lever 5a Forward switch 5b Reverse switch 6 HST lever (shift lever)
6s lever position sensor

Claims (2)

Work comprising a continuously variable transmission (3) for shifting the rotation of the engine (E) and transmitting it to the travel devices (1F, 1R) and an actuator (4) for adjusting the output rotation of the continuously variable transmission (3) The vehicle includes a forward / reverse switching lever (5) for selecting a forward / backward travel direction, a forward / backward operation detection sensor (5a, 5b) for detecting an operation position of the lever (5), and a vehicle speed of the vehicle. A shift lever (6) to be adjusted and a shift position sensor (6s) for detecting the operation position of the lever (6) are provided, and the actuator (4) is controlled according to the detected value of each sensor (5a, 5b, 6s). A speed change operation device for a work vehicle including a controller (C) for driving. The vehicle includes a main clutch (7) for turning on and off the rotational power transmitted from the engine (E) to the travel device (1F, 1R) and a clutch pedal (9) for operating the main clutch (7). The speed change lever (6) is configured in a linear shift form, the operation position of one end of the lever (6) is set to the highest speed position, and the operation position of the other end is set to the slow speed position. 2. A shift operation device for a work vehicle according to 1.

Images