JPH10250615A - Crawler operating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operating effectiveness in braking and stopping. SOLUTION: A crawler operating device makes a shifting by changing the discharge oil amount of a hydraulic pump of a hydrostatic continuously variable transmission for driving the left and the right crawler on the basis of the manipulation of a shift lever 31, wherein the arrangement further includes a pedal Pe, a drive stopping means to change the discharge oil amount to zero for shifting neutral in priority to the shift lever 31 by stamping the pedal Pe to the first setting position P1, and a braking means to give a braking force to the hydraulic motor of the hydrostatic transmission in the condition that the discharge oil amount is maintained at zero by stamping of the pedal Pe to the second setting position P2 beyond the first position P1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crawler operating device used as a traveling device of a tractor, and more particularly, to a hydrostatic type for driving a pair of right and left crawlers based on an operation of a shift lever. The present invention relates to a device that is configured to perform a traveling shift by changing a discharge oil amount of a hydraulic pump of a continuously variable transmission.

[0002]

2. Description of the Related Art Conventionally, a crawler operating device of this kind is configured to change the amount of oil discharged from a hydraulic pump of a hydrostatic continuously variable transmission, that is, to perform traveling shift only by a shift lever. . More specifically, the shift lever is used to perform braking / stopping by switching the hydrostatic continuously variable transmission to a neutral state of shifting.

[0003]

However, according to the above-mentioned conventional technique, since braking and stopping are performed manually, there is no problem for an operator who is familiar with the operation of a work machine. For those who are accustomed to the driving sensation of braking, that is, those who are used to braking and stopping by depressing the brake pedal, especially those who are not familiar with the operation of the work machine, the braking / stopping operation is uncomfortable. Therefore, the operability was not always good.

An object of the present invention is to improve the operability of braking and stopping.

[0005]

The features, functions and effects of the first aspect of the present invention are as follows.

[Features] Based on the operation of the shift lever,
An operation device for a crawler configured to perform a traveling shift by changing a discharge oil amount of a hydraulic pump of a hydrostatic continuously variable transmission for driving a pair of left and right crawlers, and provided with an operation pedal. A drive stop means for changing the discharge oil amount to zero for neutralizing the shift by giving priority to the shift lever by depressing the operation pedal to the first set position; Braking means for applying a braking force to the hydraulic motor of the hydrostatic continuously variable transmission while maintaining the discharge oil amount at zero by depressing the second setting position beyond the first setting position; It is in.

In the first aspect of the present invention, the amount of oil discharged is changed to zero prior to the shift lever by the operation of the drive stopping means based on the depression of the operating pedal to the first set position. Therefore, gently braking and stopping can be performed by depressing the operation pedal to the first set position without operating the shift lever.

Further, the braking means based on the operation of depressing the operation pedal to the first set position or the second set position applies braking force to the hydraulic motor while maintaining the discharge oil amount at zero. Therefore, the brake can be quickly stopped and stopped by depressing the operation pedal to the first set position or the second set position.

In addition, since the speed change lever is provided as it is, braking and stopping by manual operation can be performed.

[Effects] Therefore, according to the first aspect of the present invention, braking and stopping can be performed not only by manual operation using the shift lever but also by depressing operation using the operation pedal.
The operability of stopping can be improved.

According to the second aspect of the present invention, the features, functions,
The effects are as follows.

[Features] In the features of the first invention,
A negative brake for parking is provided to release the braking on the hydraulic motor against the urging in response to the application of the hydraulic pressure, and the brake can be switched between a braking release state in which the hydraulic pressure is applied to the negative brake and a braking state in which the application of the hydraulic pressure is released. A brake valve is provided, a parking brake lever for operating the brake valve is provided, and a means for switching the brake valve to a braking state prior to the parking brake lever is provided as the braking means.

[Operation] In the crawler parking technique, a negative brake for parking is provided to release the braking on the hydraulic motor against the urging in response to the application of the hydraulic pressure, and a brake releasing state in which the hydraulic pressure is applied to the negative brake. And a brake valve that can be switched between a braking state to cancel the application and
There is a technique of providing a parking brake lever for operating this brake valve to apply a parking brake.

According to the second aspect of the present invention, the above-mentioned parking brake technology is provided because the braking means is a means for switching the brake valve to the braking state prior to the parking brake lever, paying attention to the above points. When applied to crawlers, negative braking,
The brake valve can also be used.

[Effects] Therefore, according to the second aspect of the present invention, the cost can be reduced by the dual use.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of application to a tractor which is an example of a crawler traveling type working vehicle will be described. The tractor is mainly used for farming, and as shown in FIGS. 1 and 2,
Body frame 2 having a pair of right and left crawlers 1L and 1R
The engine 3 is mounted at the front of the vehicle, the riding operation unit 4 is provided at the rear, and a three-point link 6 is provided at the rear for connecting a working device (not shown) such as a tilling device so as to be able to drive up and down. ing.

Each of the crawlers 1L and 1R is connected to a track frame 7 supported and connected to the body frame 2.
The front drive sprocket 8 and the rear tension wheel 9
The crawler belt 11 is rotatably supported via a plurality of ground contact wheels 10 in between.

The riding driver 4 includes a steering handle 12, a driver's seat 13, and a cabin 14 that covers the steering wheel 12. The step 15 of the riding driver 4 covers the left and right crawlers 1L and 1R. It has been extended.

The three-point link 6 includes a pair of left and right lower links 18 for lifting and lowering the working device connected to a pair of left and right lift arms 16 via lift rods 17, respectively. The lift arm 16 is swingably moved up and down via a lift cylinder 20.

The means for driving the crawlers 1L, 1R includes a hydrostatic stepless transmission 21 (hereinafter referred to as a left crawler 1L) as a drive for individually driving the drive sprockets 8, 8 of the crawlers 1L, 1R. The corresponding one is described as 21L, and the one corresponding to the right crawler 1R is described as 21R.).

The hydrostatic stepless transmissions 21L, 21R
Are switchable between forward and backward, are driven by the power of the engine 3, change the swash plate angle by the double-acting servo cylinders 22L and 22R, and change the discharge oil amount and the discharge direction. A variable displacement hydraulic pump P that performs forward / reverse switching (the hydrostatic continuously variable transmission 2 on the left side)
1L is described as PL, and the right hydrostatic continuously variable transmission 21R is described as PR. ), And rotates using the hydraulic oil from the hydraulic pumps PL, PR as a drive source, and a single-acting sub-transmission servo cylinder 23L, 23
The variable displacement type hydraulic motor M (the left-side hydrostatic continuously variable transmission 2) that changes the rotation speed to two stages by changing the swash plate angle by R
The one for 1L is described as ML, and the one for the right hydrostatic continuously variable transmission 21R is described as MR. ).

The hydraulic pumps PL of the hydrostatic stepless transmissions 21L and 21R for the left and right crawlers 1L and 1R, respectively.
PR (hereinafter, when distinction is needed, the right crawler 1R and the corresponding hydraulic motor MR
Are called right hydraulic pump and right hydraulic motor, respectively.
The left crawler 1L and the corresponding hydraulic motor ML are referred to as a left hydraulic pump and a left hydraulic motor, respectively. ) Are arranged and connected side by side with the left hydraulic pump PL being located at the front, and a charge pump CP for generating hydraulic pressure is arranged and connected behind the right hydraulic pump PR. The drive shaft 2 protrudes from the transmission case 24 which is located at the front of the arrangement group and to which the power from the engine 3 is transmitted.
5, so that they are driven in a state of being integrally rotated.

The transmission case 24 is provided with a power transmission shaft 27 to the take-out power transmission 26 protruding rearward and also serving as a power transmission shaft to the drive shaft 25. The take-out power transmission 2
6 is provided with a power take-out shaft 29 that transmits the shifted power to the working device via a transmission shaft with a universal joint while allowing the working device to swing up and down.

Each of the hydraulic motors ML, MR is a corresponding drive sprocket 8, 8 as a wheel motor.
Is built in.

As shown in FIG. 4, each of the hydraulic motors ML and MR is urged to operate by a spring 30 in a braking state, and resists the urging by the hydraulic pressure generated by the charge pump CP. Brake B (the one corresponding to the left hydraulic motor ML is BL
And the one corresponding to the right hydraulic motor MR is BR
It is described. ) Is incorporated.

The hydrostatic continuously variable transmission 21L, 21R
An operation device for operating a main shift lever 31 which is an example of a shift lever and a forward / reverse switching lever 32 as an operation unit
And a sub-shift lever 33, a parking brake lever 34, a steering operation device, and brake means.

The main shift lever 31 is swingable around the axis, and swinging from one end of the swing range to the other end from the shift neutral position is the speed-up operation. And it is arrange | positioned beside the said driver's seat 13.

As shown in FIG. 5, the forward / reverse switching lever 32 is attached to a post 35 for the steering handle 12 so as to be able to swing back and forth around a vertical axis. The rear end is the reverse position R, and the middle between the front and rear is the neutral position N.

As shown in FIG. 5, the sub-transmission lever 33 is a two-position switching lever type switch that is turned on when one of the high-speed positions H is operated, and is turned off when the other of the low-speed positions L is operated.

The steering operation device has a steering operation tool 36 and a second steering operation tool 37. The steering operation tool 36 includes:
The steering handle 12 and a pair of left and right steering operation pedals 38L, 38R arranged at the feet of the driver's seat 13.
Consists of

Based on the operation of the steering handle 12, the hydrostatic continuously variable transmission 21L, 2
Manual steering means for individually changing the drive speed of the 1R is configured, and a foot for individually changing the drive speed of the hydrostatic continuously variable transmission 21L, 21R based on the operation of the steering operation pedals 38L, 38R. Dynamic steering means is configured.

More specifically, the manual steering means is for performing a normal turning in which the crawlers 1L and 1R inside the turning are decelerated and steered based on the steering operation of the steering handle 12. On the other hand, the foot movement steering means mainly performs the steering by decelerating the crawlers 1L and 1R inside the turning based on the steering operation performed by selectively operating the left and right steering operation pedals 38L and 38R. This is for performing a pivot turn for steering by stopping the drive of the crawlers 1L and 1R inside the rotation while performing a normal rotation. In addition, the steering operation pedals 38L, 38
R are arranged close to each other so that they can be simultaneously operated with one foot, and these steering operation pedals 38L and 38R are
A connection tool (not shown) is provided which is operable to switch between an interconnected state and a disconnected state so that they can be operated integrally.

The second steering operation tool 37 is for rotating the left and right crawlers 1L and 1R in opposite directions to perform a spin turn, and as shown in FIG. Is attached to the grip portion 31A. The push button type right turning operation tool 37R for right spin turn and the push button type left turning operation tool 37L for left spin turn are configured.

Next, the hydrostatic continuously variable transmission 21L,
The hydraulic circuit for 21R will be described. As shown in FIGS. 3 and 4, the hydraulic circuit includes the hydraulic pump P.
Hydraulic pumps PL, PR by circulating hydraulic oil between L, PR and corresponding hydraulic motors ML, MR.
And left and right motor drive circuits DCL and DCR for rotating the hydraulic motors ML and MR in accordance with the discharge oil amounts of the first and second pumps for extracting the pilot pressure for operation branched from the discharge passage 40 of the charge pump CP. An oil passage A1, a second oil passage A2 for taking out the operating oil pressure branched from the discharge passage 40, and the first oil passage A1 are connected to the respective crawlers 1L,
A branch unit 41 for branching into left and right pilot pressure paths L, R corresponding to 1R, and a double-acting servo cylinder for changing the swash plate angle of the hydraulic pumps PL, PR between the fastest forward angle and the fastest reverse angle. 22L and 22R respectively.
The left and right transmission oil passages CL, CR for applying the oil pressure in the oil passage A2, and the oil pressure in the second oil passage A2 for applying the operating pressure to the negative brakes BL, BR so as to be the operating pressure thereof. A single-acting sub-transmission servo cylinder for changing left and right brake oil passages BcL, BcR and swash plate angles of hydraulic motors ML, MR to two high and low stages using hydraulic oil in the motor drive circuits DCL, DCR as hydraulic oil. Left and right sub-transmission oil passages SCL and SCR for supplying to 23L and 23R are provided. The pilot pressure paths L and R are branched into forward operating oil paths FCL and FCR and reverse operating oil paths RCL and RCR, respectively.

The hydraulic circuit is provided with a shift control valve 42 using a variable throttle valve for changing the pilot pressure of the first oil passage A1 according to the operation of the main shift lever 31.

The transmission oil passages CL and CR are respectively provided in a forward state in which hydraulic pressure is applied to the servo cylinders 22L and 22R so as to operate the servo cylinders 22L and 22R in the forward direction. The hydraulic pressure is applied to the servo cylinder 22 so that the
L, 22R and the servo cylinder 2
Servo valves SVL and SVR are provided which can be switched between a forward and backward neutral state in which the transmission oil passages CL and CR communicate with the tank T so that the 2L and 22R are operated to the forward and backward neutral position.

These servo valves SVL, SVR are
A pilot pressure operated valve, which is urged by a spring to a forward-reverse neutral state in which a discharge oil amount of the hydraulic pumps PL, PR is reduced to zero, and the forward operation oil passages FCL, FCR
When the pilot pressure is applied from one side via the valve, the state is switched to the forward state against the bias, and the reverse operation oil passages RCL, R
When the pilot pressure is applied from the other side through the CR, the pilot pressure is switched to the reverse state against the bias. And
The hydraulic pressure applied to the servo cylinders 22L, 22R is increased or decreased according to the magnitude of the applied pilot pressure. More specifically, as the applied pilot pressure increases, the hydraulic pressure applied to the servo cylinders 22L, 22R is increased to operate the servo cylinders 22L, 22R at a higher speed.

Hydraulic oil is supplied to the sub-transmission oil passages SCL and SCR so that the swash plate angles of the sub-transmission servo cylinders 23L and 23R are operated at high speeds against the swash plate reaction force. In the high-speed state supplied to the servo cylinders 23L and 23R, the hydraulic oil in the sub-transmission servo cylinders 23L and 23R is operated so that the swash plate angle of the sub-transmission servo cylinders 23L and 23R is operated at a low speed by the swash plate reaction force. Auxiliary transmission valve 43 that can be switched to a low-speed state allowing return to tank T
L, 43R are provided. These auxiliary transmission valves 43
L and 43R are pilot pressure operated valves which are urged to a low speed state by a spring, and switch to a high speed state against application of the pilot pressure.

A third oil passage A3 is branched and connected to the second oil passage A2. The third oil passage A3 has a front end branched to the left and right brake oil passages BcL and BcR. And a sub-transmission oil passage Sc.

In the brake path Bc, the negative brakes BL, BR are connected to the tank T so as to cancel the application of the hydraulic pressure to the negative brakes BL, BR, so that the negative brakes BL, BR are braked and stopped. And a brake release state that can be switched between a brake release state in which hydraulic pressure is applied to the negative brakes BL and BR to release the brakes.
V is provided. The brake valve BV is an electromagnetic valve that is biased by a spring to a braking / stopping state, and is switched to a braking release state by being energized against the biasing.

The sub-transmission oil passage Sc is for applying a hydraulic pressure to the sub-transmission valves 43L and 43R as a pilot pressure. , 43R;
A high / low switching valve 44 is provided which is capable of switching to a low speed state in which the applied oil pressure is released to the tank T. The elevation switching valve 44 is an electromagnetic valve that is urged to a low speed state by a spring and is switched to a high speed state by being energized against the urging.

The pressure-change control oil passages AL and AR are branched and connected to the speed-change oil passages CL and CR, respectively.
These pressure reduction control oil passages AL and AR are connected to tanks T and T, respectively, so as to reduce the oil pressure.
And pressure-reducing valves VL and VR that can be switched between a pressure-reducing state in which communication with the tank T is performed and a non-pressure-reducing state in which communication with the tank T is interrupted to maintain the oil pressure.

These pressure reducing valves VL, VR are pilot pressure operated valves, are urged by a spring to a non-pressure-reduced state, and are provided with the steering operation pedals 38L, 38R.
Cylinder MC that can be pressurized by stepping on
The pressure generated by the L and MCR is switched to a reduced pressure state according to the pilot pressure against the bias as the pilot pressure. The pressure-reducing valves VL, VR are set to the maximum pressure-reduced state when the steering operation pedals 38L, 38R are depressed to the maximum, and the servo cylinders 22L, 22R are returned to the gear-shift neutral state.

Therefore, when the servo cylinders 22L, 22R are in the forward or backward state and the crawlers 1L, 1R are in the forward or backward operation, one of the left and right steering operation pedals 38L, 38R is depressed. When you operate,
The pressure reducing valves VL, VR corresponding to the depressed side steering operation pedals 38L, 38R are switched from the non-depressurized state to the depressurized state corresponding to the stepping operation amount, and the depressed side steering operation pedal 38L. , 38R, the hydraulic pressure applied to the servo cylinders 22L, 22R is reduced to a pressure corresponding to the stepping operation amount, so that the discharge oil amounts of the hydraulic pumps PL, PR on the stepped side become the stepping operation amount. The steering operation pedal 38L on the side that has been depressed and depressed to the corresponding one
Hydraulic motors ML and MR corresponding to 38R decelerate, and as a result, steering operation pedals 38L and 38 on the side on which the step operation is performed.
The crawler 1L, 1R corresponding to R is decelerated to a speed corresponding to the amount of stepping operation, and normal turning is performed. In particular, when one of the left and right steering operation pedals 38L and 38R is depressed to the maximum, the steering operation pedal 38 on the side on which the stepping operation is performed is performed.
When the servo cylinders 22L and 22R corresponding to the left and right steering wheels 38L and 38R return to the shift neutral state, the discharge oil amounts of the hydraulic pumps PL and PR corresponding to the steering operation pedals 38L and 38R on the side where the stepping operation is performed become zero. Hydraulic pump PL,
As a result, the hydraulic pumps PL and PR corresponding to the depressed operation steering pedals 38L and 38R are stopped, so that the depressed operation control pedals 38L and 38R are turned on. Corresponding crawlers 1L, 1
The drive of R stops, and a pivot-like turn is performed.

When the steering operation pedals 38L, 38R are simultaneously depressed, the pressure reducing valves VL, VR are switched from a non-pressure reducing state to a pressure reducing state in accordance with the stepping operation amount, and are applied to the servo cylinders 22L, 22R. Is reduced to a pressure corresponding to the stepping operation amount, the discharge oil amounts of the two hydraulic pumps PL, PR decrease to those corresponding to the stepping operation amount, and the hydraulic motors ML, MR decelerate and stop, as a result,
Both crawlers 1L and 1R are decelerated and stopped at a speed corresponding to the amount of stepping operation. In addition, EQ is the both steering operation pedal 3
8L and 38L are operated at the same time, and even if there is some variation in the operation amount of the operation and there is a difference between the pressures generated by the master cylinders MCL and MCR, the pressures are reduced by the two pressure reducing valves VL and VR. This equalizer acts as a pilot pressure equal to and operates the pressure reducing valves VL and VR equally, so that the two hydraulic motors ML and MR are equally decelerated.

The hydraulic circuit includes a forward switching valve FV.
L, FVR and reverse switching valves RVL, RVR are provided, and a steering valve V and a turning mode switching valve MV are provided in series.

The forward switching valves FVL and FVR are interposed in the forward operation oil passages FCL and FCR, and are provided in a forward state where pilot pressure is applied to the servo valves SVL and SVR, and in a non-forward state where no pilot pressure is applied. The solenoid valve is operable to be biased to a non-advanced state by a spring, and switches to a forward state by energizing against the bias.

The reverse switching valves RVL, RVR are interposed in the reverse operation oil passages RCL, RCR, and are used for a reverse state where pilot pressure is applied to the servo valves SVL and SVR, and a non-reverse state where pilot pressure is not applied. The solenoid valve is operated and biased to a non-reverse state by a spring, and switches to a reverse state by being excited by being excited.

The steering valve V is connected to the servo valve SV.
The steering of the crawlers 1L and 1R is controlled by controlling the application of pilot pressure applied to the L and SVRs. To the left turning state.

More specifically, the steering handle 1
2 is in a straight running state, the left and right pilot pressure paths L, R
Without connecting to the tank T
By applying a pilot pressure equal to L and SVR, the two servo cylinders 22L and 22R are brought into the same state, and the two crawlers 1L and 1R are rotated at the same speed, so that the straight traveling state is reached. Accordingly, by connecting only the right pilot pressure path R to the right hydraulic pump PR to the tank T, the pilot pressure applied to the right servo valve SVR is reduced as the right turning operation amount is increased, so that the right pilot pressure path R is reduced. Operate the servo cylinder 22R in the deceleration direction and set the right hydraulic pump P
By controlling the discharge oil amount of R to an amount corresponding to the right turning operation amount, the traveling speed of the crawler 1R on the right side (inside of turning) is reduced to a speed corresponding to the right turning operation amount, so that a right turning state is achieved. On the other hand, as the left turning operation of the steering handle 12 is performed, only the left pilot pressure path L for the left hydraulic pump PL is communicated with the tank T, so that as the left turning operation amount increases, the left servo valve SVL is applied to the left servo valve SVL. By lowering the pilot pressure to be operated, the left servo cylinder 22L is operated in the deceleration direction and the left hydraulic pump P
By controlling the discharge oil amount of L to the amount corresponding to the left turning operation amount, the running speed of the left (turning inside) crawler 1R is reduced to the speed corresponding to the left turning operation amount, and the state becomes the right turning state. is there.

The characteristics of the steering valve V are as shown in FIG.
The pilot pressure gradually decreases as the steering angle of the steering handle 12 increases. Further, the higher the pilot pressure, the larger the straight traveling dead zone F with respect to the steering angle of the steering handle 12 (the maximum speed becomes maximum), and the steering when the hydraulic pumps PL and PR are brought into the neutral state (zero speed). The turning angle of the handle 12 increases. In other words, when the pilot pressure is high, the straight traveling state is maintained even when the steering handle 12 is slightly turned, and when the pilot pressure is low, the steering is performed by slightly turning the steering handle 12.
Accordingly, as the main shift lever 31 is operated to the high speed side and the pilot pressure is increased, the turning angle of the steering handle 12 required to reduce the pilot pressure to the same pilot pressure is increased, thereby avoiding a sharp turn during high speed traveling. It's easier.

As shown in FIGS. 1, 3 and 5, the brake means is provided to the main shift lever 31 by a braking operation pedal Pe and an operation of depressing the operation pedal Pe to a first set position P1. A drive stop means for preferentially changing the discharge oil amounts of the hydraulic pumps PL and PR to zero for a neutral shift, and a stepping operation of the operation pedal Pe to a second set position P2 beyond the first set position P1. Hydraulic pump PL,
With the discharge oil amount of the PR maintained at zero, the hydraulic motors ML,
And a braking means for applying a braking force to the MR.

The drive stopping means is provided with a first position detection switch PS1 for detecting that the operation pedal Pe has been depressed to a position equal to or higher than the first set position P1, and the first oil passage A1 is connected to the tank T by excitation. With the communication, the pilot pressure is reduced to zero and the servo valves SVL and SVR are switched to the neutral state in the forward and backward directions regardless of the operation state of the shift control valve 42, thereby switching to a stop state against the urging force of the spring and canceling the excitation. The tank T of the first oil passage A1
A stop solenoid valve VT that switches to a stop release state in which communication with the shift control valve 42 is cut off by cutting off communication with the first position detection switch PS.
A stop control device SC is provided to excite the stop solenoid valve VT based on the detection of No. 1 and release the excitation based on non-detection.

The brake means detects that the operation pedal Pe has been depressed to a position equal to or higher than the second set position P2.
A position detection switch PS2 is provided, and a brake control device BC is provided which de-energizes the brake valve BV based on the detection of the second position detection switch PS2 and excites based on non-detection. The braking control device BC is incorporated in a control device C described later together with the stop control device SC.

The turning mode switching valve MV can be freely switched between a normal turning state in which the steering valve V is connected to the tank T and a spin turn state in which the steering valve V is not connected to the tank T in any state. This is a solenoid valve that is operated and biased to a normal turning state by a spring, and is switched to a spin-turn state by being energized against the bias.

The operating device is provided with a control device C. The functions (control contents) of the control device C are the following [1] to [7].

[1] A forward signal is output when the forward / reverse switching lever 32 is operated to the forward position F,
Outputs a reverse signal when operated to the reverse position R, and outputs a neutral signal when operated to the forward / backward neutral position N. When the output signal from the forward / backward neutral determination switch 32S is a forward signal. , Forward switching valves FVL, FVR
And when the output signal is a reverse signal or a neutral signal, the excitation of the forward switching valves FVL and FVR is released.

[2] The forward / reverse neutral switch 32S
When the output signal from the reverse is a reverse signal, the reverse switching valve RV
L and RVR are excited, and when the output signal is a forward signal or a neutral signal, the excitation of the reverse switching valves RVL and RVR is released.

[3] The forward-reverse neutral switch 32S
When the output signal is a neutral signal, the swing mode switching valve MV is excited, and when the output signal is a forward signal or a reverse signal, the excitation of the swing mode switching valve MV is released.

[4] The forward / reverse neutral switch 32S
By turning on the right turning switch RTS which is reversibly turned on by the operation of the right turning operation tool 37R in a state where the output signal from is a neutral signal, the left crawler 1L rotates in the forward direction, The forward switching valve FVL for the left crawler 1L and the reverse switching valve RVR for the right crawler 1R are excited so that the right crawler 1R rotates in the reverse direction and performs a right spin turn, and the right turning switch RT
Excitation is released by turning off S.

[5] The forward-reverse neutral switch 32S
When the left turning switch LTS, which is reversibly turned on by the operation of the left turning operation tool 37L in a state where the output signal from is a neutral signal, is turned on, the right crawler 1R is turned in the forward direction and the left crawler 1R is turned on. The forward switching valve FVR for the right crawler 1R and the reverse switching valve RVL for the left crawler 1L are excited so that the crawler 1L rotates in the reverse direction and performs a left spin turn, and the left turning switch LT
Excitation is released by turning off S.

[6] The parking switch PS which is turned on by the operation of the parking brake lever 34 to the braking release position and turned off by the operation of the braking position is turned on to excite the brake valve BV, and the parking switch is turned on. PS
, The excitation of the brake valve BV is released.

[7] The high / low switching valve 44 is excited when the sub-transmission switch 33 is turned on, and the excitation is released when it is turned off.

SV is the left and right motor drive circuits DCL, D
A safety valve for the CR, S1 is a throttle for avoiding mutual interference of pilot pressures between the left and right pilot pressure paths L and R, and S2 is a left and right transmission oil path CL,
This is a throttle for avoiding mutual interference of hydraulic pressure between CRs.

According to the above configuration, the forward straight traveling mode, the reverse straight traveling mode, the forward normal right turning mode, the forward normal left turning mode, the reverse normal right turning mode, the reverse normal left turning mode, the forward right pivot turn Mode, forward left pivot turn mode, reverse right pivot turn mode, reverse left pivot turn mode, right spin turn mode, and left spin turn mode.

Each mode will be described below. <Forward straight traveling mode> This is a mode in which the left and right crawlers 1L and 1R are rotated in the forward direction at a constant speed to travel straight, and the steering handle 12 is operated in the straight traveling state, and the forward / reverse switching lever 32 is moved to the forward position F. Can be obtained by operating That is, the operation of the forward / reverse switching lever 32 to the forward position F causes the left and right forward switching valves FVL and FVR to move.
Is switched to the forward state, whereby the servo valves SVL and SVR are both switched to the forward state at a speed corresponding to the pilot pressure of the pressure corresponding to the operating position of the main shift lever 31, and the states of the servo valves SVL and SVR are changed. The hydraulic pressure of the size and direction according to the servo cylinder 22L,
22R, the swash plates of the left and right hydraulic pumps PL, PR are equally operated at an angle corresponding to the applied hydraulic pressure, so that the discharge oil amounts and discharge directions of the left and right hydraulic pumps PL, PR become equal. , Whereby the left and right hydraulic motors M
The left and right crawlers 1L and 1R rotate in the forward direction at a constant speed by rotating the left and right MRs at the same speed in the same direction. By operating the main transmission lever 31, the pilot changed accordingly. It travels at a speed corresponding to the pressure. In this forward straight traveling mode, when the left and right steering operation pedals 38L, 38R are simultaneously depressed, the pressure reducing valves VL, VR are both brought into a depressurized state according to the depressed operation amount, and both servo cylinders 22L, 2
2R operates in a state corresponding to the stepping operation amount, and the discharge oil amounts of the left and right hydraulic pumps PL, PR decrease equally, and the speeds of the left and right hydraulic motors ML, MR both decrease to the speed corresponding to the stepping operation amount. Then, the left and right crawlers 1L and 1R decelerate equally. In particular, when the left and right steering operation pedals 38L, 38R are simultaneously depressed to the maximum, the pressure reducing valves VL, VR are both in the maximum pressure reducing state, and the two servo cylinders 22L, 22R are operated in the shifting neutral state. Then, the discharge oil amounts of the left and right hydraulic pumps PL and PR become zero, the left and right hydraulic motors ML and MR both stop, and the driving of the left and right crawlers 1L and 1R stops. That is, without operating the main shift lever 31 to the neutral position N or operating the forward / reverse switching lever 32 to the neutral position N, the two steering operation pedals 38L and 38R can be simultaneously depressed. Speed reduction and stop of traveling can be performed.

<Reverse / straight running mode> Left and right crawlers 1
This is a mode in which the vehicle travels straight by rotating the L and 1R in the reverse direction at the same speed, and is obtained by operating the steering handle 12 in the straight traveling state and operating the forward / reverse switching lever 32 to the reverse position R. That is, the operation of the forward / reverse switching lever 32 to the reverse position R causes the left / right reverse switching valve R to move.
VL and RVR are switched to the reverse state, whereby
Servo valves SVL and SVR are both main shift lever 31
Is switched to a reverse state at a speed corresponding to the pilot pressure of the pressure corresponding to the operation position of the servo valve SVL,
The hydraulic pressure in the magnitude and direction according to the state of the SVR is applied to the servo cylinders 22L and 22R, and the left and right hydraulic pumps P
By operating the swash plates L and PR equally at an angle corresponding to the applied hydraulic pressure, the discharge oil amounts and discharge directions of the left and right hydraulic pumps PL and PR are equalized, and thereby the left and right hydraulic motors ML and ML are driven. By rotating the MR at the same speed in the same direction, the left and right crawlers 1L and 1R rotate in the reverse direction at the same speed.
The vehicle travels at a speed corresponding to the pilot pressure changed accordingly. In this reverse straight running mode, when the left and right steering operation pedals 38L and 38R are simultaneously depressed as in the forward straight running mode,
Accordingly, both the pressure reducing valves VL and VR enter a pressure reducing state in accordance with the amount of stepping operation, and the two servo cylinders 22L and 22R
Operates in a state corresponding to the stepping operation amount, the discharge oil amounts of the left and right hydraulic pumps PL, PR decrease equally, and the speeds of the left and right hydraulic motors ML, MR both decrease to the speed corresponding to the stepping operation amount. , The left and right crawlers 1L and 1R decelerate equally. In particular, when the left and right steering operation pedals 38L and 38R are simultaneously depressed to the maximum, the pressure reducing valve V
Both L and VR are in the maximum decompression state, and both servo cylinders 22L and 22R operate in the neutral state of shifting, the discharge oil amount of the left and right hydraulic pumps PL and PR becomes zero, and the left and right hydraulic motors ML and MR Are stopped, and the driving of the left and right crawlers 1L and 1R is stopped. That is, without operating the main shift lever 31 to the neutral position N or operating the forward / reverse switching lever 32 to the neutral position N, the two steering operation pedals 38L and 38R can be simultaneously depressed. Speed reduction and stop of traveling can be performed.

<Normal forward right turning mode> This is a mode in which the front traveling speed of the crawler 1R inside the turning (right side) is reduced in the forward traveling state, and there are a manual operation mode and a foot operation mode.

The manual operation mode is obtained by steering the steering handle 12 rightward in the forward state. That is, the steering valve V is switched to the right turning state by the steering operation of the steering handle 12 to the right, and the pilot pressure applied to the right servo valve SVR becomes a pressure corresponding to the steering angle of the steering handle 12. As a result, only the right servo valve SVR is switched to the forward state at a speed corresponding to the reduced pilot pressure, and the hydraulic pressure in the magnitude and direction according to the state of the right servo valve SVR is reduced to the right. By being applied to the servo cylinder 22R and operating the swash plate of the right hydraulic pump PR at an angle corresponding to the applied hydraulic pressure, the amount of oil discharged from the right hydraulic pump PR decreases, thereby reducing As the rotational speed of the hydraulic motor MR decreases, the forward traveling speed of the right crawler 1R becomes slower than that of the left crawler 1L, whereby the turning is performed.

The foot operation mode is obtained by depressing the right steering operation pedal 38R in the forward movement state. That is, by depressing the right steering operation pedal 38R, only the right pressure reducing valve VR is reduced, and the hydraulic pressure applied to the right servo cylinder 22R decreases,
As a result, the swash plate angle of the right hydraulic pump PR is changed to an angle corresponding to the reduced hydraulic pressure, and the discharge oil amount of the right hydraulic pump PR is reduced to a value corresponding to the stepping operation amount. The rotation speed of the hydraulic motor MR becomes lower, so that the forward traveling speed of the right crawler 1R becomes slower than that of the left crawler 1L, thereby turning.

<Normal forward left turning mode> In the forward running state, there is a mode in which the forward running speed of the crawler 1L on the inner side of the turning (left side) is reduced to make a turn, and there are a manual operation mode and a foot operation mode.

The manual operation mode is obtained by steering the steering handle 12 to the left in the forward movement state. That is, the steering valve V is switched to the left turning state by the steering operation of the steering handle 12 to the left, and the pilot pressure applied to the left servo valve SVL becomes a pressure corresponding to the steering angle of the steering handle 12. As a result, only the left servo valve SVL is switched to the forward state at a speed corresponding to the reduced pilot pressure, and the hydraulic pressure in the magnitude and direction corresponding to the state of the left servo valve SVL is changed to the left servo valve. When the swash plate of the left hydraulic pump PL is applied to the cylinder 22L and is operated at an angle corresponding to the applied hydraulic pressure, the amount of oil discharged from the left hydraulic pump PL is reduced. As the rotational speed of the motor ML decreases, the forward traveling speed of the left crawler 1L becomes slower than that of the right crawler 1R, thereby turning.

The foot operation mode is obtained by depressing the left steering operation pedal 38L in the forward state. That is, by depressing the left steering operation pedal 38L, only the left pressure reducing valve VL is in a reduced pressure state, and the hydraulic pressure applied to the left servo cylinder 22L is reduced,
As a result, the swash plate angle of the left hydraulic pump PL is changed to an angle corresponding to the reduced hydraulic pressure, so that the discharge oil amount of the left hydraulic pump PL is reduced to a value corresponding to the stepping operation amount, and , The forward traveling speed of the left crawler 1L becomes slower than that of the right crawler 1R, thereby turning.

<Reverse Normal Right Turn Mode> This is a mode in which the reverse traveling speed of the crawler 1R on the inside of the turn (right side) is reduced while the vehicle is traveling backward, and there are a manual operation mode and a foot operation mode.

The manual operation mode is obtained by steering the steering handle 12 rightward in the reverse state. That is, the steering valve V is switched to the right turning state by the steering operation of the steering handle 12 to the right, and the pilot pressure applied to the right servo valve SVR becomes a pressure corresponding to the steering angle of the steering handle 12. As a result, only the right-side servo valve SVR is switched to the reverse state at a speed corresponding to the lowered pilot pressure, and the hydraulic pressure in the magnitude and direction according to the state of the right-side servo valve SVR is reduced to the right side. By being applied to the servo cylinder 22R and operating the swash plate of the right hydraulic pump PR at an angle corresponding to the applied hydraulic pressure, the amount of oil discharged from the right hydraulic pump PR decreases, thereby reducing As the rotational speed of the hydraulic motor MR decreases, the reverse traveling speed of the right crawler 1R becomes slower than that of the left crawler 1L, thereby turning.

The foot operation mode is obtained by depressing the right steering operation pedal 38R in the reverse state. That is, by depressing the right steering operation pedal 38R, only the right pressure reducing valve SVR is reduced in pressure, and
The hydraulic pressure applied to the right servo cylinder 22R decreases, and as a result, the swash plate angle of the right hydraulic pump PR is changed to an angle corresponding to the reduced hydraulic pressure, so that the discharge oil amount of the right hydraulic pump PR Is reduced in accordance with the stepping operation amount, and the rotation speed of the right hydraulic motor MR is reduced, so that the reverse traveling speed of the right crawler 1R becomes slower than that of the left crawler 1L, thereby turning. .

<Reverse Normal Left Turning Mode> This is a mode in which the reverse traveling speed of the crawler 1L inside the turning (left side) is reduced while the vehicle is traveling backward, and there are a manual operation mode and a foot operation mode.

The manual operation mode is obtained by steering the steering wheel 12 to the left in the reverse state. That is, the steering valve V is switched to the left turning state by the steering operation of the steering handle 12 to the left, and the pilot pressure applied to the left servo valve SVL becomes a pressure corresponding to the steering angle of the steering handle 12. As a result, only the left servo valve SVL is switched to the reverse state at a speed corresponding to the reduced pilot pressure, and the hydraulic pressure in the magnitude and direction corresponding to the state of the left servo valve SVL is changed to the left servo valve. When the swash plate of the left hydraulic pump PL is applied to the cylinder 22L and is operated at an angle corresponding to the applied hydraulic pressure, the amount of oil discharged from the left hydraulic pump PL is reduced. As the rotational speed of the motor ML decreases, the reverse traveling speed of the left crawler 1L becomes slower than that of the right crawler 1R, thereby turning.

The foot operation mode can be obtained by depressing the left steering operation pedal 38L in the reverse state. That is, by depressing the left steering operation pedal 38L, only the left pressure reducing valve SVL is in a reduced pressure state,
The hydraulic pressure applied to the left servo cylinder 22L decreases, and as a result, the swash plate angle of the left hydraulic pump PL is changed to an angle corresponding to the reduced hydraulic pressure, so that the discharge oil amount of the left hydraulic pump PL Is reduced according to the amount of stepping operation, and the rotational speed of the left hydraulic motor ML is reduced, so that the reverse traveling speed of the left crawler 1L becomes slower than that of the right crawler 1R, thereby turning. .

<Forward right pivot turn mode> This is a mode in which the drive to the crawler 1R inside the turn (right side) is stopped in the forward running state and the vehicle turns, and in the forward state, the right steering operation pedal 38R is fully depressed. Obtained by manipulating. That is, the right steering operation pedal 38R
With the maximum depressing operation of the right side, the right pressure reducing valve SVR is switched to the reduced pressure state, and the hydraulic pressure for the right servo cylinder 22R is reduced, whereby the right servo cylinder 22R is operated to the neutral state, and the right hydraulic pump When the amount of oil discharged from the PR becomes zero, the right hydraulic motor PR stops, and the driving of the right crawler 1R stops.

<Leading Left Pivot Turn Mode> This is a mode in which the driving of the crawler 1L inside the turning (left side) is stopped in the forward running state and the turning is performed. In the forward state, the left steering operation pedal 38L is fully depressed. Obtained by manipulating. That is, the left steering operation pedal 38L
With the maximum depressing operation of the left side, the pressure reducing valve SVL on the left side is switched to the pressure reducing state, and the hydraulic pressure for the left side servo cylinder 22L is reduced, whereby the left side servo cylinder 22L operates to the neutral state, and the left hydraulic pump When the discharge oil amount of the PL becomes zero, the left hydraulic motor PL stops, and the driving of the left crawler 1L stops.

<Reverse Right Pivot Turn Mode> This is a mode in which the drive to the crawler 1R on the inner side (right side) of the turn is stopped in the reverse running state and the vehicle turns, and in the reverse state, the right steering operation pedal 38R is fully depressed. Obtained by manipulating. That is, the right steering operation pedal 38R
With the maximum depressing operation of the right side, the right pressure reducing valve SVR is switched to the reduced pressure state, and the hydraulic pressure for the right servo cylinder 22R is reduced, whereby the right servo cylinder 22R is operated to the neutral state, and the right hydraulic pump When the discharge oil amount of the PR becomes zero, the right hydraulic motor MR stops, and the drive to the right crawler 1R stops.

<Reverse Left Pivot Turn Mode> This is a mode in which the drive to the inner side (left side) crawler 1L is stopped in a reverse traveling state and the vehicle turns, and in the reverse state, the left steering operation pedal 38L is fully depressed. Obtained by manipulating. That is, the left steering operation pedal 38L
With the maximum depressing operation of the left side, the pressure reducing valve SVL on the left side is switched to the pressure reducing state, and the hydraulic pressure for the left side servo cylinder 22L is reduced, whereby the left side servo cylinder 22L operates to the neutral state, and the left hydraulic pump When the discharge oil amount of the PL becomes zero, the left hydraulic motor ML stops and the left crawler 1L stops.

<Right spin turn mode> This mode is a mode in which the right crawler 1R is rotated in the reverse direction and the left crawler 1L is rotated in the forward direction at the same speed in the traveling stopped state, and the right and left crawlers 1R are turned forward and backward. It can be obtained by operating the right turning operation tool 37R in a state where the switching lever 32 is operated to the neutral position N in the forward / reverse direction. That is, when the forward / backward switching lever 32 is operated to the forward / backward neutral position N, the output signal from the forward / backward neutral determination switch 32S becomes a neutral signal, and the turning mode switching valve MV switches to the spin turn state. When the right turning switch RTS is turned on by the operation of the right turning operation tool 37R, the left crawler 1 is turned on.
L, the forward switching valve FVL is in the forward state, and the reverse switching valve RVR corresponding to the right crawler 1R.
Are respectively switched to the reverse state, whereby the left servo valve SVL is switched to the forward state by the pilot pressure corresponding to the operation position of the main shift lever 31, and the left servo cylinder 22L is switched to the forward speed state corresponding to the state.
Is operated, the swash plate of the left hydraulic pump PL is operated forward at an angle corresponding to the pilot pressure,
The right servo valve SVR is switched to the reverse state by the pilot pressure corresponding to the operation position of the main shift lever 31, and the right servo cylinder 22R is operated in the reverse speed state corresponding to the state, whereby the right hydraulic pump PR is tilted. The plate is operated on the reverse side at an angle corresponding to the pilot pressure,
As a result, the left hydraulic motor ML rotates forward and the right hydraulic motor MR rotates backward and at the same speed defined by the main shift lever 31, and the left crawler 1L rotates.
Rotate in the forward direction, and the right crawler 1R rotates in the reverse direction at the same speed. Then, by releasing the operation on the right turning operation tool 37R, the forward switching valve FVL and the reverse switching valve RVR are switched to the non-forward state and the non-reverse state, respectively.
The servo valves SVL and SVR enter the neutral state for shifting, and the servo cylinders 22L and 22R both enter the neutral state.
The turning is stopped.

<Left Spin Turn Mode> This is a mode in which the left crawler 1L is rotated in the reverse direction and the right crawler 1R is rotated in the forward direction at the same speed when the vehicle is stopped, and the vehicle is driven forward and backward. It can be obtained by operating the left turning operation tool 37L in a state where the switching lever 32 is operated to the forward / backward neutral position N. That is, when the forward / backward switching lever 32 is operated to the forward / backward neutral position N, the output signal from the forward / backward neutral determination switch 32S becomes a neutral signal, and the turning mode switching valve MV switches to the spin turn state. When the left turning switch LTS is turned on by the operation of the left turning operation tool 37L, the right crawler 1 is turned on.
The forward switching valve FVR corresponding to R is in the forward state, and the reverse switching valve RVL corresponding to the left crawler 1L.
Are respectively switched to the reverse state, whereby the right servo valve SVR is switched to the forward state by the pilot pressure corresponding to the operation position of the main shift lever 31, and the right servo cylinder 22R is switched to the forward speed state corresponding to the state.
Is operated, the swash plate of the left hydraulic pump PL is operated forward at an angle corresponding to the pilot pressure,
The left servo valve SVL is switched to the reverse state by the pilot pressure corresponding to the operation position of the main shift lever 31, and the left servo cylinder 22L is operated to the reverse speed state corresponding to the state, whereby the right hydraulic pump PR is inclined. The plate is operated on the reverse side at an angle corresponding to the pilot pressure,
As a result, the right hydraulic motor MR rotates forward and the left hydraulic motor ML rotates backward and at the same speed defined by the main shift lever 31, and the right crawler 1R rotates.
Rotate in the forward direction, and the left crawler 1L rotates at the same speed in the reverse direction. Then, by releasing the operation on the left turning operation tool 37L, the forward switching valve FVR and the reverse switching valve RVL are switched to the non-forward state and the non-reverse state, respectively.
The servo valves SVL and SVR enter the neutral state for shifting, and the servo cylinders 22L and 22R both enter the neutral state.
The turning is stopped.

The manual steering means comprises a steering valve V, forward switching valves FVL, FVR, and a reverse switching valve RV.
L, RVR and servo valves SVL, SVR, and the foot movement steering means is used as master cylinders MCL, MCR.
And pressure reducing valves VL and VR.

The servo cylinder 22 for changing the inclination angle of the hydraulic pumps PL, PR of the hydrostatic continuously variable transmissions 21L, 21R based on the steering operation of the steering operation tool 36.
Servo valves SVL and SV for the servo cylinders 22L and 22R so that the one corresponding to the crawler 1L or 1R inside the turning is operated in the deceleration direction.
The control means for controlling the pilot pressure applied to R comprises a steering valve V, forward switching valves FVL, FVR, and reverse switching valves RVL, RVR.
The shifting means for equally increasing or decreasing the pilot pressure applied to the two servo valves SVL and SVR based on the operation of the shift control valve 42 is provided. Servo valve SVL,
Forward / backward switching means for switching the application direction of the pilot pressure applied to the SVR to switch the discharge directions of the hydraulic pumps PL and PR in the forward and reverse directions comprises forward switching valves FVL and FVR.
And a forward / reverse switching valve RVL, RVR, and a forward / backward neutral determination switch 32S constitutes a restraint means that permits switching to the spin turn mode only when the forward / backward switching lever 32 is in a neutral state. ing.

In any of the modes, when the operating pedal Pe is depressed to a position equal to or higher than the first set position P1, the servo valves SVL and SVR return to the neutral state, and the discharge oil amounts of the hydraulic pumps PL and PR become zero. When the operation pedal Pe returns to the original position and performs the return operation, the mode returns to the mode before the pedal operation. When the operation pedal Pe is depressed to a position equal to or higher than the second set position P2, the servo valves SVL and SVR return to the neutral state, the discharge oil amounts of the hydraulic pumps PL and PR become zero, and the negative brakes BL and BR are released. When the brake pedal is operated to return to the first set position P1 and operated while returning to the first set position P1, the operation pedal Pe returns to the original position and then returns to the original position to perform the return operation. Then, the mode returns to the mode before the pedal operation.

[Alternative Embodiment] In the above embodiment, the hydrostatic stepless transmissions 21L and 21R are provided corresponding to the crawlers 1L and 1R, respectively. 21 and the left and right crawlers 1L, 1R
May be driven.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor showing an embodiment.

FIG. 2 is a front view of the tractor showing the embodiment.

FIG. 3 is a hydraulic circuit diagram showing an embodiment.

FIG. 4 is a hydraulic circuit diagram showing an embodiment.

FIG. 5 is a control block diagram showing an embodiment.

FIG. 6 is an explanatory diagram of characteristics of a steering valve according to the embodiment.

[Explanation of symbols]

 1L, 1R Crawler 21 Hydrostatic continuously variable transmission P Hydraulic pump M Hydraulic motor 31 Shift lever B Negative brake Pe Operating pedal BV Brake valve 34 Parking brake lever

Continued on the front page (72) Inventor Seiichi Takahashi 64 Ishizu-Kitamachi, Sakai City, Osaka Prefecture Inside Kubota Sakai Works, Ltd.

Claims (2)

[Claims] A traveling speed change is performed by changing a discharge oil amount of a hydraulic pump of a hydrostatic continuously variable transmission for driving a pair of right and left crawlers based on an operation movement of a speed change lever. A crawler operating device,
An operation pedal is provided, and drive stop means is provided for changing the discharge oil amount to zero for neutralizing a shift by prioritizing the shift lever by depressing the operation pedal to a first set position. A braking means for applying a braking force to the hydraulic motor of the hydrostatic continuously variable transmission while maintaining the discharge oil amount at zero by depressing a set position or a second set position exceeding the first set position. Crawler operating device provided. 2. A negative brake for parking which releases braking to the hydraulic motor against urging in response to the application of hydraulic pressure is provided, and a braking release state in which hydraulic pressure is applied to the negative brake and a braking state in which application of hydraulic pressure is released And a parking brake lever for operating the brake valve, and a means for switching the brake valve to a braking state prior to the parking brake lever is provided as the braking means. Crawler operating device.