JPH0564064U - Turning control structure of work vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] With an automatic speed reducer, when performing a slow braking turn by applying a small braking force in a hard field, the increase in running resistance is slight and the speed does not slow down. Although it is good, it will be slowed down, eliminating the inconvenience that hinders work efficiency. [Structure] In a combine equipped with an automatic speed reducer that automatically operates the HST1 at a low speed when a braking turn is performed by braking a crawler traveling device on one side, a braking force applied to the crawler traveling device by a hydraulic braking mechanism. However, the braking mechanism is configured such that the braking mechanism becomes stronger as the circuit pressure of the hydraulic circuit rises and becomes weaker as the circuit pressure decreases, and the operation amount of the hydraulic cylinder 53 to the low speed side of the HST 1 is set to this. The internally mounted two-stage spring configures the hydraulic cylinder 53 in a state in which it increases as the circuit pressure increases and decreases as the circuit pressure decreases.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an automatic deceleration device when turning in a work vehicle such as a combine or a multi-wheel carrier, and more specifically, a pair of left and right traveling devices, a continuously variable transmission for these traveling devices, and both traveling devices. A hydraulic braking mechanism that applies a braking action to the selected one of them, and a hydraulic actuator that operates the continuously variable transmission to a low speed side when the circuit pressure to the braking mechanism exceeds a set value. Related to the turning control structure of the working vehicle.

[0002]

[Prior Art]

 Conventionally, as a turning control structure of this type, as in the combine disclosed in Japanese Patent Laid-Open No. 3-104784, the hydraulic pressure required for the braking mechanism is used when turning sharply with one side crawler braking. The operating cylinder operates the continuously variable transmission to the low speed side to decelerate, thereby preventing the engine due to the increase in running resistance.

[0003]

[Problems to be solved by the device]

 In the above-mentioned prior art, when the vehicle makes a sharp turn after braking, it is always decelerated. However, for example, in the case of performing a slowly controlled turn with a slight braking force applied in a relatively hard field, the increase in running resistance is slight and it is not necessary to decelerate. Since it slows down even at any time, it sometimes hinders work efficiency. An object of the present invention is to eliminate the above-mentioned inconvenience due to the automatic deceleration while having an engine stall prevention function at the time of braking turn by the automatic deceleration.

[0004]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a turning control structure for a working vehicle described at the beginning, wherein the braking force applied to the traveling device by the braking mechanism becomes stronger as the circuit pressure increases, and In addition to configuring the braking mechanism so that it weakens as the pressure decreases, the amount of operation of the hydraulic actuator toward the low speed side of the continuously variable transmission increases as the circuit pressure increases, and the circuit pressure increases. The feature of the present invention is that the hydraulic actuator is configured so that the hydraulic actuator decreases in number with the decrease.

[0005]

[Action]

 In other words, the stronger the braking force, the greater the running resistance, and accordingly the higher the braking force acting on the traveling device on one side, the larger the deceleration rate. This allows the turning speed to be increased as quickly as possible with a relatively low deceleration rate during gentle braking, and as fast as possible within a range that does not require a relatively large deceleration rate during locked braking. It becomes possible to set. Since the deceleration rate is adjusted and set by utilizing the fact that the operation amount of the hydraulic actuator that controls the deceleration operation changes in response to the fluctuation of the circuit pressure, the above-mentioned method can be performed without adding a new mechanism. It becomes possible to exert the action.

[0006]

[Effect of the device]

 Therefore, it is possible to reduce unnecessary deceleration during turning by using a relatively simple device that configures the hydraulic actuator as a variable type in which the operation amount changes with the increase or decrease of the supply pressure, thus reducing the work efficiency. We were able to provide something that could be improved.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 7 and 8 show the structure of the inside of the transmission case 8 of the traveling system of the combine, which is one of the work vehicles. The power from the engine (not shown) is provided with a belt transmission mechanism (not shown) equipped with a tension clutch. ) Is transmitted to the input pulley 2 of the hydrostatic continuously variable transmission (hereinafter abbreviated as HST) 1, and the power from the output shaft 3 of the HST 1 is transmitted from the first transmission shaft 4 to the one-way clutch 5 and output. It is transmitted to the reaper 6 shown in FIG. 9 via the pulley 7. The power from the first transmission shaft 4 is transmitted to the second transmission shaft 11 via the first gear 9 and the second gear 10, and the first high speed gear 12 is fitted onto the second transmission shaft 11 so as to be relatively rotatable. The shift gear 14 is slidably fitted onto the spline. On the other hand, the second high-speed gear 16 and the low-speed gear 17 are fixed to the third transmission shaft 15, the first high-speed gear 12 meshes with the second high-speed gear 16, and the third transmission shaft 15 has a middle shaft. The high speed gear 18 is fixed. With the above-described structure, the shift gear 14 is slid and engaged with the first high speed gear 12, the medium speed gear 18, and the low speed gear 17, so that the power can be shifted into three stages of high, medium and low. Is transmitted to the third gear 19 which is engaged with the. A right side gear 21R and a left side gear 21L are fitted to the support shaft 20 supporting the third gear 19 so as to be rotatable relative to each other, and the input gears 23L, 23R of the left and right axles 22L, 22R are attached to the left and right side gears 21L, 21R. It is always biting. As a result, the right or left side gears 21R and 21L are slid on the third gear 19 so as to be engaged and separated, and the power transmission is turned on and off with respect to the drive sprocket 24a of the crawler type traveling device 24 shown in FIG. The operation is performed, and side clutches 25L and 25R are formed between the third gear 19 and the left and right side gears 21L and 21R.

Next, the case where braking is applied to one of the axles 22R or 22L will be described in detail. As shown in the figure, the right fourth gear 26R and the left fourth gear 26L are relatively rotatable with respect to the support shaft 20. A pair of fifth gears 29 supported by bearings and fixed to the fourth transmission shaft 27 mesh with the right fourth gear 26R and the left fourth gear 26L. A multi-plate hydraulically operated side brake 28 (corresponding to the braking mechanism) is provided at one end of the fourth transmission shaft 27, and the right side gear 21R or the left side gear 21L is separated from the third gear 19 and the right fourth gear. By engaging the gear 26R or the left fourth gear 26L and operating the side brake 28, it is possible to apply braking to one of the axles 22R or 22L. It is possible to reveal a turning state in which the traveling device is locked by the braking force. Next, the structure for reversing one of the axles 22R or 22L will be described in detail. As shown in the figure, the sixth gear 62 meshing with the second high speed gear 16 of the third transmission shaft 15 becomes the fourth transmission shaft 27. A hydraulic clutch 30 is provided between the sixth gear 62 and the fourth transmission shaft 27 while being fitted to the outside so as to be rotatable relative to each other. As a result, when the right side gear 21R or the left side gear 21L is engaged with the right fourth gear 26R or the left fourth gear 26L as described above, when the hydraulic clutch 30 is operated, the power from the second high speed gear 16 is generated. In the reverse rotation state, the speed is reduced to 1/2 and is transmitted to the axle 22R or 22L. And this is a super-confidential turning state.

Next, the hydraulic oil supply structure to the hydraulic cylinders 31 L and 31 R side brakes 28 and the hydraulic clutch 30 for sliding the left and right side gears 21 L and 21 R will be described in detail. As shown in FIG. Is supplied to the hydraulic cylinders 31L and 31R for the left and right side gears 21L and 21R via the first switching valve 33, and the oil passage 34 from the side surfaces of the hydraulic cylinders 31L and 31R is provided to the side brake 28 and the hydraulic clutch. 30 is connected to the second switching valve 35, and the oil passage 34 is connected to the side brake 28 and the variable relief valve 36 for the hydraulic clutch 30. The relief valve 61 keeps the pressure of the entire hydraulic circuit at a safe allowable pressure. Next, the operation of the first switching valve 33, the second switching valve 35, and the variable relief valve 36 will be described in detail. As shown in FIG. 6, the operation lever 39 that can be operated in the front-rear and left-right directions is mechanically linked to the first switching valve 33, the second switching valve 35, and the variable relief valve 36. For example, the operation lever 39 is in the neutral position. First turning position R from N to the right₁ Or left first turning position L ₁ When operated to, only the first switching valve 33 is operated, and the right or left side gear 21R, 21L engaged with the third gear 19 is operated by the hydraulic cylinder 31R or 31L via the right or left operating portion 46R, 46L. Is separated from the third gear 19 and meshes with the right or left fourth gear 26R, 26L. In this case, since the variable relief valve 36 is in the fully open state and both the side brake 28 and the hydraulic clutch 30 are in the disengaged state, the transmission to the right or left axle 22R, 22L is cut off ( The side clutch 25R or 25L is disengaged), and the aircraft makes a gentle turn to the right or left. The sequence valve 47 provided in the oil passage 34 supplies the pressure required for the right or left side gear 21R, 21L to completely mesh with the right or left fourth gear 26R, 26L. It is intended to secure.

Next, when the operating lever 39 is operated from the right or left first turning position R ₁ , L ₁ to the right or left second turning position R ₂ , L ₂ , the right or left side gear 21R, 21L is moved to the right. Alternatively, the variable relief valve 36 is gradually closed from the fully opened state while being engaged with the left fourth gears 26R and 26L, and with the second switching valve 35 operated to the hydraulic oil supply side to the side brake 28. Will be operated by. As a result, the side brakes 28 start to act, and braking is gradually applied to the right or left axle 22R, 22L, and the aircraft makes a braking turn to the right or left. Then, the braking force of the side brake 28 is maximized at the right or left second turning position R ₂ , L ₂ of the operating lever 39, and the solid turning state is revealed. Next, when the operating lever 39 is operated to the right or left third turning position R ₃ , L ₃ , the second switching valve 35 is switched to the hydraulic oil supply side to the hydraulic clutch 30 in the above-mentioned state. As a result, the side brake 28 is turned off, the hydraulic clutch 30 is turned on, and the right or left axle 22R, 22L is reversely driven, and the airframe makes a super turning turn to the right or left. The third switching valve 37 for the hydraulic cylinder 60 for raising and lowering the reaper 6 and the operating lever 39 are mechanically linked. As a result, the reaper 6 can be moved up and down by operating the operating lever 39 to the raised position or the lowered position (upward or backward of the plane of the drawing).

Next, the gear shift operation structure of the HST 1 will be described in detail. As shown in FIGS. 1 and 3, the bracket 13 is swingably supported around the horizontal axis P ₁ in the body control section, and the gear shift lever 38 is attached to the bracket 13. On the other hand, as shown in FIG. 1, a gear shift operation arm 40 (corresponding to a gear shift operation portion) is fixed to the trunnion shaft 1a of the HST 1, and the gear shift operation arm 40 and the first arm 13a of the bracket 13 are extended. The link rod 41 is installed. As shown in FIG. 3, a thin disk-shaped ring gear 43 is fixed to the boss portion 42 on which the bracket 13 is relatively rotatably fitted. As shown in FIG. Further, a drive gear 44a of a vehicle speed control servomotor 44, which will be described later, is engaged. Further, a friction plate 45 is sandwiched between the bracket 13 and the ring gear 43, and a disc spring 48 for pressing the bracket 13 toward the ring gear 43 is provided. With the above structure, the servo motor 44 is stopped when the vehicle speed control is not performed, and the ring gear 43 is a fixed member. Therefore, the operator can artificially shift the HST 1 by operating the speed change lever 38, and even if the operator releases his / her hand from the speed change lever 38 at a certain shift position, the HST1 is operated by the biasing force of the disc spring 48. The shift lever 38 is held at the shift position of.

Next, the structure of vehicle speed control using the servo motor 44 will be described in detail. This vehicle speed control detects the rotation speed of an engine (not shown), obtains a work load based on this rotation speed, and uses a ring gear 43 by a servo motor 44 so that the work load is maintained within a set range. Is rotated to operate the gear shift operation arm 40 of the HST 1 via the bracket 13. In this case, a potentiometer 49 for detecting the angle of the bracket 13 and feeding it back to a control device (not shown) is provided. That is, as shown in FIGS. 1 and 3, the pin 49 b at the tip of the rotary detection arm 49 a of the potentiometer 49 is inserted into the long hole 13 c of the second arm 13 b of the bracket 13, and the angle of the bracket 13 is changed. Is detected as the angle of the detection arm 49a. An elastic accommodation mechanism 50 is provided in the middle of the linking rod 41, and its structure will be described in detail. As shown in FIG. 1, the linking rod 41 is composed of an upper rod 41a connected to the bracket 13 and a lower rod 41b connected to the gear shift operation arm 40 of the HST 1, and the upper rod 41a has a cylindrical member. 50a is fixed. Then, the spring 50d is attached between the receiving member 50b fixed to the upper end of the lower rod 41b and the ring member 50c fixed to the lower end of the cylindrical member 50a in a state compressed more than its natural length. There is. As a result, the spring 50d does not contract during the manual shift by the shift lever 38 and the automatic shift by the servomotor 44, and the angle of the bracket 13 and the position of the shift operating arm 40 correspond to each other. When the vehicle speed control is performed by the servo motor 44, as shown in FIG. 1, after the gear shift operation arm 40 of the HST 1 reaches the forward-side maximum speed position F _MAX (the gear shift operation arm 40 does not move any more), When the servomotor 44 tries to move the bracket 13 to the high speed side, the spring 50d of the elastic accommodation mechanism 50 contracts to perform this operation. When the bracket 13 is slightly moved further to the high speed side after the speed change operation arm 40 reaches the maximum speed position F _MAX , this operation is detected by the potentiometer 49 and the servo motor 44 is stopped. There is. As a result, the HST 1 can be used without waste from the neutral position N to the forward maximum speed position F _MAX during vehicle speed control.

Next, the configuration for automatically decelerating the HST 1 at the time of braking turn using the side brake 28 and at the time of turning to the ground and at the time of super turning by using the hydraulic clutch 30 will be described in detail. .. As shown in FIGS. 1 and 4, the operated portion 51 having a T-shaped cross section and the lower rod 41b of the link rod 41 are attached to the tip of the speed change operation arm 40 by one bolt 52. .. An L-shaped member 51a formed by bending a bar is fixed to the operated portion 51, and a hydraulic cylinder 53 (corresponding to a hydraulic actuator) is arranged above the L-shaped member 51a. There is. As shown in FIG. 6, an oil passage 54 branched from the oil passage 34 is connected to the hydraulic cylinder 53. As shown in FIGS. 1 and 10, the hydraulic cylinder 53 is internally provided with a first spring 53b and a second spring 53c for urging the piston 53a toward the retracting side. The first spring 53b is provided so as to extend over the piston 53a and the lid member 53d, and the interval between the stop portion 53e of the piston 53a and the lid member 53d is S.₁And the free length of the second spring 53c mounted between the cylinder body 53f and the piston 53a is S₂I made it short. That is, the circuit pressure is set to P₁Below, due to the action of the second spring 53c, which is a strong spring, the projecting operation amount of the piston rod 53g is S₂It is kept below, and P₂As described above, the second spring 53c is also compressed and the piston rod 53g is moved to the full stroke, that is, S₁It will be in a protruding state. Circuit pressure is P₁And P₂During this period, the amount of protrusion of the piston rod 53g gradually increases corresponding to the compression operation range of the second spring 53c, but as a whole, the gradually increasing range is extremely small. Therefore, as shown in the graph in FIG. The operation amount of the hydraulic cylinder 53 substantially changes in two steps depending on the circuit pressure. Therefore, the operation lever 39 is moved to the first turning position R₁, L₁When it is operated to the₂The automatic deceleration is performed and the first turning position R₁, L ₁ And the second turning position R₂, L₂Intermediate position R with_Four, L_FourWhen the piston rod 53g is operated to the full stroke (= S₁) Prominent automatic deceleration will be performed.

With the structure described above, when the side brake 28 or the hydraulic clutch 30 is operated to turn during the forward movement with the shift lever 38 operated to a certain shift position, the pressure in the oil passage 34 in FIG. 6 increases. .. Therefore, the high-pressure hydraulic oil in the oil passage 34 flows into the hydraulic cylinder 53 via the oil passage 54. As a result, as shown in FIG. 2, the piston 53a extends and contacts the L-shaped member 51a, pushes down the gear shift operation arm 40 of the HST1 toward the neutral position N, and the HST1 is automatically decelerated. .. When the gear shift operation arm 40 is operated in this manner, the spring 50d of the elastic accommodation mechanism 50 is only compressed, and the gear shift lever 38 does not move due to the holding action of the disc spring 48. When the turning is completed and the side brake 28 or the hydraulic clutch 30 is disengaged (the variable relief valve 36 is returned to the fully open state), the pressure in the oil passages 34 and 54 is reduced, and the spring 53b of the hydraulic cylinder 53 is released. As a result, the piston 53a is retracted upward. As a result, the spring 50d of the elastic accommodation mechanism 50 is stretched, and the shift operation arm 40 of the HST 1 automatically returns to the position corresponding to the shift position of the shift lever 38. In this structure, the elastic accommodation mechanism 50 is an accommodation for using the HST1 from the neutral position N to the highest speed position F _MAX on the forward side without waste during vehicle speed control, and for automatic deceleration during turning. It is also flexible and will have both functions. In the above state, the automatic deceleration is performed at the time of braking turn, turning at the turning point, and turning at the super turning point. However, as shown in FIG. Then, even if the piston 53a of the hydraulic cylinder 53 extends, it cannot contact the L-shaped member 51a of the operated portion 51. As a result, the automatic deceleration operation is not performed when turning. In this embodiment, the hydrostatic continuously variable transmission H is used as the continuously variable transmission 1. However, a belt type continuously variable transmission may be used instead of this, and a crawler type traveling device 24 is provided. The present invention can be applied to a six-wheeled or eight-wheeled wheeled vehicle instead of a work vehicle. Further, it is also possible to set two or more switching positions of the operation amount of the hydraulic cylinder 53 so as to change in three or more steps, or to change infinitely in proportion to the swing operation amount of the operation lever 39.

As shown in FIGS. 12 and 13, a tire 71 can be mounted on the drive sprocket 24 a of the crawler traveling device 24, and a high-speed caster wheel 72 for adjusting the vertical position is provided at the rear portion of the crawler traveling device 24 a. It is designed to be mobile. The tire 71 can be changed to a traveling state by the tire 71 by mounting the crawler traveling device 24 which can be lifted and lowered to the ground, and then raising the crawler traveling device 24 to the ground, so that a jack or the like is not necessary.

In the claims of the utility model, reference numerals are given for convenience of comparison with the drawings, but the invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a side view showing a structure in which a shift lever and an HST are linked together.

FIG. 2 is a side view showing a state where the HST is decelerated from the state shown in FIG.

FIG. 3 is a cross-sectional plan view of the vicinity of a bracket that supports a shift lever.

FIG. 4 is a vertical cross-sectional rear view of the tip of the gear shift operation arm in HST.

FIG. 5 is a side view showing the linkage structure in which the operated portion is turned in a different direction and automatic deceleration is not performed.

FIG. 6 is a hydraulic circuit diagram of first, second and third switching valves and a variable relief valve.

FIG. 7 is a vertical sectional front view of the mission case.

FIG. 8 is a vertical sectional front view of the mission case following FIG.

FIG. 9 is an overall side view of the combine.

FIG. 10 is a sectional view showing the structure of a hydraulic cylinder.

FIG. 11 is a graph showing changes in extension of the hydraulic cylinder with respect to circuit pressure.

FIG. 12 is a side view showing a tire running state.

FIG. 13 is a sectional view showing a tire mounting structure.

[Explanation of symbols]

 1 Hydrostatic Stepless Transmission 24 Traveling Device 28 Braking Mechanism 53 Hydraulic Actuator

Claims (1)

[Scope of utility model registration request] 1. A pair of left and right traveling devices (24), (24)
And a continuously variable transmission (1) for the traveling devices (24), (24), and a hydraulic braking mechanism for braking the selected one of the traveling devices (24), (24). (2
8), and a hydraulic actuator (53) for operating the continuously variable transmission (1) to a low speed side when the circuit pressure for the braking mechanism (28) exceeds a set value.
In a turning control structure for a work vehicle, the braking force applied to the traveling device (24) by the braking mechanism (28) increases as the circuit pressure increases, and the circuit pressure increases. The braking mechanism (28) is configured to become weaker with a decrease in the hydraulic pressure, and the operation amount of the hydraulic actuator (53) to the low speed side of the continuously variable transmission (1) increases the circuit pressure. A turning control structure for a work vehicle in which the hydraulic actuator (53) is configured in a state in which the hydraulic actuator (53) increases in number with a decrease in the circuit pressure.