JP3170394B2 - Travel transmission structure of work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling vehicle equipped with a continuously variable transmission capable of steplessly shifting between a neutral position where transmission is not performed and a predetermined maximum speed position. Transmission structure.

[0002]

2. Description of the Related Art When a continuously variable transmission as described above is provided for traveling, if the continuously variable transmission is operated to a neutral position, power is not transmitted to a traveling device on the lower side, so that the aircraft is temporarily stopped. Can be. In this case, if the aircraft is temporarily stopped by operating the continuously variable transmission to the neutral position on a slope, etc., the aircraft may descend along the slope. Equipped with a brake and operating the continuously variable transmission to the neutral position,
It has been proposed to configure a brake for temporary stop to be automatically operated to the braking side.

[0003]

Since the above-mentioned structure is provided with a dedicated brake for temporary stop, there is room for improvement in terms of simplification of the structure and cost reduction. The present invention
A continuously variable transmission capable of steplessly shifting between a neutral position where transmission is not performed and a predetermined maximum speed position is used in a traveling transmission structure of a working vehicle provided for traveling while using an existing structure. It is another object of the present invention to obtain a configuration that can prevent the body from moving when the continuously variable transmission is temporarily stopped by operating the transmission at a neutral position.

[0004]

The feature of the present invention resides in the following construction in the traveling power transmission structure for a working vehicle as described above. The power from the engine is transmitted to a continuously variable transmission that is capable of steplessly shifting between a neutral position where transmission is not performed and a predetermined maximum speed position, and a lower transmission system of the continuously variable transmission is connected to the second transmission. The power transmission system includes a forward clutch that transmits forward power and a reverse clutch that transmits reverse power, to each of the transmission systems branched in parallel to the two systems,
The traveling power transmission system is configured to transmit the power from the forward and reverse clutches to the traveling device, and when the artificially operated speed change operation device is operated from the neutral position to the forward high speed side, the forward clutch is operated. As the reverse operation is performed, the reverse clutch is disengaged and the continuously variable transmission is operated from the neutral position to the high speed side, and the shift operation tool is operated from the neutral position to the reverse high speed side, the forward movement is performed. First linking means for linking the speed change device and the continuously variable transmission, and the forward and reverse clutches, such that the clutch is disengaged, the reverse clutch is engaged, and the continuously variable transmission is operated from the neutral position to the high speed side; When the shift operating device is operated to the neutral position, both the forward clutch and the reverse clutch are operated to be engaged, so that the continuously variable transmission is operated to the neutral position. , It is a second linking means for linking the forward and reverse clutch.

[0005]

According to the first aspect of the present invention, there is provided a continuously variable transmission capable of performing a stepless shift operation between a neutral position where transmission is not performed and a predetermined maximum speed position. The transmission system on the lower side is branched into two systems in parallel, and a forward clutch and a reverse clutch are arranged in each of the transmission systems branched into two systems. Thus, according to the first aspect of the present invention, when the speed change operation device is operated to the neutral position, both the lower forward and reverse clutches are engaged, and the upper continuously variable transmission is operated to the neutral position. Therefore, the power of the engine is not transmitted from the continuously variable transmission on the upstream side to the downstream side, and the aircraft temporarily stops.

In this state, for example, when the body is going to move forward on a slope or the like, the traveling device is going to be driven to the forward side, and this operation goes back through the transmission system of the forward clutch and the transmission system of the reverse clutch. A branch point is reached on the lower side where the system branches into two transmission systems. As a result, at the branch point where the downstream side of the continuously variable transmission branches into two transmission systems, the two operations going back in the transmission system of the forward clutch and the transmission system of the reverse clutch try to act in opposite directions to each other. Thus, the traveling device is apparently braked. Therefore, it is not necessary to provide a dedicated brake for temporary stop when the shift operation tool is operated to the neutral position, in addition to the brake used for braking during traveling.

[II] Since the continuously variable transmission as described in the above item [I] cannot perform the forward / reverse switching operation, when such a continuously variable transmission is provided, the stepless transmission is simultaneously performed. It is necessary to equip a forward / backward switching device with a forward / backward clutch. Thus, according to the features of the first aspect, the braking action as described in the above item [I] can be obtained only by engaging and operating both the forward and reverse clutches, which can be said to be existing structures.

[III] According to the feature of the first aspect, when the shift operation tool is operated to the neutral position and both the forward and reverse clutches on the lower side are engaged and operated as described in the above [I]. Then, the superior continuously variable transmission is operated to the neutral position, and the power of the engine is cut off by the superior continuously variable transmission. By operating the upper continuously variable transmission to the neutral position and shutting off the power of the engine in this way, the two transmission systems on the lower side of the continuously variable transmission as described in [I] above. The state in which the two operations act in opposite directions at the branch point does not work back to the engine, and does not cause the engine to stop.

[0009]

According to the first aspect of the present invention, there is provided a work vehicle equipped with a continuously variable transmission capable of steplessly shifting between a neutral position where transmission is not performed and a predetermined maximum speed position. In the traveling power transmission structure, the forward and reverse clutches, which can be said to be the existing structures, are effectively used, so that the gearshift operating device can be operated to the neutral position without the need for the temporary stop brake. A configuration in which braking is applied during a temporary stop was obtained, and the structure of the work vehicle was simplified and cost was reduced. According to the first aspect of the present invention, when the shift operation device is operated to the neutral position and both the forward and reverse clutches on the lower side are engaged, the continuously variable transmission on the upper side is operated to the neutral position. Therefore, the state of stopping the engine is avoided beforehand.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. [1] FIG. 1 shows a structure of a transmission case 8 of a traveling system in a combine, which is an example of a work vehicle, in which a power of an engine (not shown) is provided with a belt transmission mechanism (not shown) having a tension clutch. The power is transmitted to the input pulley 2 of the belt-type continuously variable transmission 1 via the output shaft 3, and the power from the output shaft 3 of the continuously variable transmission 1 is transmitted via the output pulley 4 to a reaper (see FIG. ).

The continuously variable transmission 1 has a split pulley type in which each of the input and output pulleys has a pair of pulley portions facing each other, and changes the distance between the pulley portions of the input and output pulleys to wind the transmission belt. A gear change operation is performed by changing the turning radius. By dropping the power transmission belt into the boss between the pair of pulleys in the input pulley on the lower side, a neutral position where power is not transmitted to the output pulley on the lower side appears, and the continuously variable transmission 1 is described above. Between the neutral position and the predetermined highest speed position. The power of the output shaft 3 of the continuously variable transmission 1 is transmitted to the transmission system via the output gear 13 and the hydraulic multi-plate friction type forward clutch FC, and to the output gear 3.
0, intermediate gear 37 and hydraulic multiple disc friction type reverse clutch R
It is divided in parallel into two transmission systems via C and transmitted to the first transmission shaft 5.

The forward power (forward clutch FC) or the reverse power (reverse clutch RC) transmitted to the first transmission shaft 5 is transmitted via the first gear 9 and the second gear 10 to the second power.
The power is transmitted to the transmission shaft 11. A shift gear 14 is externally slidably fitted to the second transmission shaft 11 in a spline structure, and a high-speed gear 16, a medium-speed gear 17 and a low-speed gear 6 are fixed to the third transmission shaft 15. As a result, the shift gear 14 is slid and engaged with the high-speed gear 7, the medium-speed gear 17 or the low-speed gear 6 meshing with the high-speed gear 16, and the forward (reverse) power is shifted into three stages of high, medium and low. That is, the forward (reverse) power is transmitted to the first transmission gear 19 that meshes with the middle speed gear 17.

A support shaft 20 for supporting the first transmission gear 19
A right side gear 21R and a left side gear 21L are externally fitted so as to be relatively rotatable, and the input gear 23 of the right and left axles 22 is connected to the right and left side gears 21R and 21L.
Is always occluded. As a result, the right or left side gears 21R and 21L are slid into and out of engagement with the first transmission gear 19 to perform power transmission and transmission cutoff operations to the crawler type traveling device 24. 1 transmission gear 19 and right and left side gears 21R, 21L
The side clutches 25R and 25L are configured between the two.

[2] This combine is configured so that one traveling device 24 can be braked to perform a pivot turn. Next, the structure of the pivot turn will be described. As shown in FIG. 1, a hydraulic side brake 28 is provided between one end of the fourth transmission shaft 27 and the transmission case 8. The second transmission gears 26R, 26L are supported by bearings on both left and right ends of the support shaft 20, and the fourth transmission gear 29 fixed to both ends of the fourth transmission shaft 27 meshes with the second transmission gears 26R, 26L. I have.

As a result, the right or left side gear 21
When the side brake 28 is turned on with the R and 21L engaged with the right or left second transmission gears 26R and 26L, braking is applied to one of the traveling devices 24. In this case, the other side gears 21 </ b> R and 21 </ b> L are engaged with the first transmission gear 19, and the forward (reverse) power is transmitted to the other traveling device 24, so that the aircraft turns pivotally.

[3] In this combine, one of the traveling devices 24 is driven at a lower speed than the other so as to perform a gentle turning. The structure of the next gentle turning will be described. As shown in FIG.
A small-diameter output gear 38 is fixed to the boss portion of the first transmission gear 19, and a large-diameter third transmission gear 40 is fitted to the fourth transmission shaft 27 so as to be relatively rotatable. 3
8 is occluded. Third transmission gear 40 and fourth transmission shaft 27
, A hydraulic slow turning clutch 12 is provided.

As a result, the right or left side gear 21
When the gentle turning clutch 12 is engaged with the R and 21L engaged with the right or left second transmission gears 26R and 26L, the forward (reverse) power transmitted to the first transmission gear 19 is output. The gear 38, the third transmission gear 40, the gentle turning clutch 12, the fourth transmission shaft 27, the fourth transmission gear 29, and the right or left second transmission gear 26R, 26L are reduced to one third and reduced to one third. It is transmitted to the traveling device 24. in this case,
The other side gears 21 </ b> R and 21 </ b> L are engaged with the first transmission gear 19, and power for forward (reverse) transmission is transmitted to the other traveling device 24, and the aircraft is driven by a speed difference between the right and left traveling devices 24. Turn slowly.

[4] Next, a structure for supplying hydraulic oil to the hydraulic cylinders 31R, 31L, the gentle turning clutch 12, and the side brake 28 for performing the sliding operation of the right and left side gears 21R, 21L will be described. As shown in FIG. 2, the hydraulic oil from the pump 32 is supplied to the hydraulic cylinders 31R, 31L for the right and left side gears 21R, 21L via the first switching valve 33, and from the side of the hydraulic cylinders 31R, 31L. The oil passage 34 is provided with the gentle turning clutch 12 and the side brake 28.
The variable relief valve 36 for the gentle turning clutch 12 and the side brake 28 is connected to the oil passage 34.

An operation lever 3 for turning operation is provided on a control portion of the aircraft.
9 is provided, and an operation lever 39 and a first switching valve 33 are provided.
And the variable relief valve 36 are mechanically linked via linking mechanisms 41 and 42. The second switching valve 35 includes a gentle turning position 35 a for supplying hydraulic oil to the gentle turning clutch 12,
And a pivot position 35b for supplying hydraulic oil to the side brake 28. The second switching valve 35 is operated by a switching lever 18 provided in a control section of the fuselage.

[5] With the above structure, the second switching valve 35 is operated by the switching lever 18 to the gentle turning position 35a. If the operation lever 39 is operated to the neutral position N in this state, the first switching valve 3
3 is also operated to the neutral position, and the right and left hydraulic cylinders 31
R, 31L contracts, and the right and left side gears 21R,
21L is in mesh with the first transmission gear 19. As a result, the forward (reverse) power transmitted to the first transmission gear 19 is transmitted to the right and left traveling devices 24, and the right and left traveling devices 24 are driven at the same speed, so that the aircraft goes straight. .

Next, when the operating lever 39 is operated from the neutral position N to the first turning position R1 on the right or the first turning position L1 on the left, only the first switching valve 33 is operated and the hydraulic cylinder 3 is operated.
The right or left operation unit 46R, 46R can be operated by 1R or 31L.
Through L, the right or left side gear 21R, 21L that has engaged with the first transmission gear 19 is separated from the first transmission gear 19 and engages with the right or left second transmission gear 26R, 26L.

In this case, since the variable relief valve 36 is in the fully opened state and the gentle turning clutch 12 is in the disengaged state, the transmission to the right or left traveling device 24 is cut off (the state of the side clutch 25R or 25L). (Transmission cutoff state), and the aircraft gradually changes its direction to the right or left. The sequence valve 47 provided in the oil passage 34 controls the pressure required for the right or left side gear 21R, 21L to completely engage with the right or left second transmission gear 26R, 26L.
This is for securing the hydraulic cylinders 31R and 31L.

Next, the operating lever 39 is moved from the right or left first turning position R1, L1 to the right or left second turning position R2, L.
2, the right or left side gear 21R, 2
1L is engaged with the right or left second transmission gear 26R, 26L and the second switching valve 35 is operated to the gentle turning position 35a, and the variable relief valve 36 is gradually operated from the fully opened state to the closed side. Will be done. As a result, the slow turning clutch 12 starts to operate, and the right or left traveling device 24 is gradually driven at a low speed, and the aircraft slowly turns right or left. At the right or left second turning position R2, L2 of the operation lever 39, the gentle turning speed becomes maximum.

[6] Next, the second switching valve 35 is operated to the pivot position 35b by the switching lever 18. If the operating lever 39 is operated to the neutral position N in this state, the vehicle is in a straight-ahead state as described in [5] above, and the operating lever 39 is moved from the neutral position N to the right or left first turning position R1. , L1, the transmission cutoff state of the right or left side clutch 25R, 25L appears.

Next, the operating lever 39 is moved from the right or left first turning position R1, L1 to the right or left second turning position R2, L.
2, the right or left side gear 21R, 2
1L is engaged with the right or left second transmission gear 26R, 26L, and the second switching valve 35 is operated to the pivot position 35b, in the same manner as described in the preceding item [5]. Is gradually moved from the fully opened state to the closed side. As a result, the side brake 28 starts to act, and the braking is gradually applied to the right or left traveling device 24, so that the aircraft turns right or left. At the right or left second turning position R2, L2 of the operation lever 39, the side brake 2
8, the braking force becomes maximum.

[7] Next, the operation structure of the continuously variable transmission 1 and the forward and reverse clutches FC and RC shown in FIG. 1 will be described. 3 and 2
As shown in (1), the operating oil of the pump 32 is supplied from the pressure reducing valve 43 to the forward and reverse clutches FC, RC via the third switching valve 44 and the accumulator 45. Oil passage 48 of variable relief valve 36 and oil passage 4 of first switching valve 33
9 joins the oil passage 50, and is configured to supply the hydraulic oil discharged from the variable relief valve 36 and the first switching valve 33 from the oil passage 50 to the forward and reverse clutches FC and RC as lubricating oil. ing.

As shown in FIG. 4, a shift lever 51 (corresponding to a shift operation tool) is provided in the control section of the fuselage. The shift lever 51 and the continuously variable transmission 1 shown in FIG. 1 and the continuously variable transmission 1 shown in FIG. The three switching valves 44 are mechanically linked. The state shown in FIG. 4 is a state in which the shift lever 51 is being operated to the neutral position N of the lever guide 52, and the third state as shown in FIG.
The switching valve 44 is operated to the neutral position 44N, and the continuously variable transmission 1 shown in FIG. 1 is also operated to the neutral position where power is not transmitted. In this state, the operating oil is supplied from the third switching valve 44 to both the forward and reverse clutches FC and RC, and both the forward and reverse clutches FC and RC are engaged (the above corresponds to the second linking means). ).

In this case, when the operating lever 39 shown in FIG. 2 is operated to the neutral position N (the position where the left and right side gears 21R and 21L engage with the first transmission gear 19), the transmission lever 51 is neutralized as described above. Assume that the user has operated to the position N. In this state, the continuously variable transmission 1 is operated to the neutral position, and the aircraft temporarily stops. In this state, for example, it is assumed that the aircraft attempts to move forward along a slope.

When the right and left traveling devices 24 are driven in the forward direction in this manner, the operation is performed by the first transmission gear 19, the third transmission shaft 15, and the second transmission shaft 11 as shown in FIG. And the first transmission shaft 5, and attempts to rotate the output shaft 3 forward from the first transmission shaft 5 via the forward clutch FC. On the other hand, the power that goes back to the first transmission shaft 5 branches and tries to rotate the output shaft 3 to the reverse side via the reverse clutch RC and the intermediate gear 37. As described above, the forward and reverse clutches FC, R from the first transmission shaft 5
The operations branched via C try to act on the output shaft 3 in opposite directions, so that the output shaft 3 cannot rotate. Thus, the right and left traveling devices 24 are apparently braked. Therefore, the state where the aircraft tries to move along the slope is prevented.

[8] Next, when the shift lever 51 is operated to the forward stop position FA of the lever guide 52 from the state shown in FIG. 4, the third switching valve 44 is operated to the forward stop position 44FA as shown in FIG. Thus, both the forward and reverse clutches FC and RC are disengaged, and the continuously variable transmission 1 shown in FIG. 1 is left at the neutral position. When the shift lever 51 is operated from the forward stop position FA to the forward position FB along the lever guide 52, FIG.
3 is operated to the forward position 44FB, the forward clutch FC is engaged, and the continuously variable transmission 1 shown in FIG. 1 is operated from the neutral position to the high speed side. At the forward position FB, the continuously variable transmission 1 is at the highest speed position (the above corresponds to the first linking means).

As described above, when the third switching valve 44 is operated from the forward stop position 44FA to the forward position 44FB,
Due to the operation of the accumulator 45 shown in FIG. 3, the pressure of the forward clutch FC increases with the characteristic shown by the solid line in FIG. At the same time, the continuously variable transmission 1 is also operated from the neutral position to the high-speed side. Therefore, when the continuously variable transmission 1 is operated from the neutral position to the high-speed side, the airframe near the neutral position of the continuously variable transmission 1 The position where the effective power to start moving the vehicle is transmitted (see the position indicated by the dashed line in FIG. 5) substantially coincides with the second half position of the forward clutch FC in the half-clutch state, so that the aircraft smoothly pauses It is configured to start moving forward from the state.

Next, from the state shown in FIG.
Is operated to the reverse stop position RA of the lever guide 52,
As shown in FIG. 3, the third switching valve 44 is in the reverse stop position 44R.
A, the forward and reverse clutches FC and RC are both disengaged, and the continuously variable transmission 1 shown in FIG. 1 remains at the neutral position. Shift lever 51 to lever guide 52
When the vehicle is operated from the reverse stop position RA to the reverse position RB along the line, the third switching valve 44 shown in FIG.
1 to operate the reverse clutch RC, and the continuously variable transmission 1 shown in FIG. 1 is operated from the neutral position to the high speed side. The high-speed position is reached (the above corresponds to the first linking means).

When the third switching valve 44 is operated from the reverse stop position 44RA to the reverse position 44RB as described above,
Due to the operation of the accumulator 45 shown in FIG. 3, the pressure of the reverse clutch RC increases with the characteristic shown by the solid line in FIG. At the same time, the continuously variable transmission 1 is also operated from the neutral position to the high-speed side. Therefore, when the continuously variable transmission 1 is operated from the neutral position to the high-speed side, the airframe near the neutral position of the continuously variable transmission 1 The position where the effective power to start moving the vehicle is transmitted (see the position indicated by the dashed line in FIG. 5) substantially coincides with the second half position of the reverse clutch RC in the half-clutch state, and the aircraft is temporarily stopped smoothly. It is configured to start reverse from the state.

[Another Embodiment] In the configuration shown in FIG. 1, a belt-type continuously variable transmission 1 is
The continuously variable transmission 1 using a tapered cone may be configured. The present invention can be applied not only to the combine as shown in FIG. 1 but also to a four-wheel type work vehicle equipped with front wheels and rear wheels.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a transmission structure of a transmission case.

FIG. 2 is a hydraulic circuit diagram of right and left side gear hydraulic cylinders, a first switching valve, a second switching valve, a variable relief valve, and the like.

FIG. 3 is a hydraulic circuit diagram of a forward and reverse clutch, a third switching valve, an accumulator, etc.

FIG. 4 is a plan view of a shift lever and a lever guide.

FIG. 5 is a diagram showing a relationship between a pressure increase characteristic of a forward and reverse clutch and a position where power effective to start moving the vehicle near a neutral position of the continuously variable transmission is transmitted.

[Explanation of symbols]

 Reference Signs List 1 continuously variable transmission 24 traveling device 51 speed change operation tool FC forward clutch RC reverse clutch N neutral position

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI // F16H 59:04 (72) Inventor Shigenobu Nobuno 64, Ishizukita-cho, Sakai-shi, Osaka Kubota Sakai Works (72 ) Inventor Mineyoshi Motomura 64 Ishizukita-cho, Sakai-shi, Osaka Kubota Sakai Works Co., Ltd. (56) References JP-A-5-180302 (JP, A) Japanese Utility Model Application Sho 62-20251 (JP, U) (58 ) Surveyed field (Int.Cl. ⁷ , DB name) B60K 41 / 00,41 / 22 B60K 17/08 F16H 61/16 F16H 59/00

Claims (1)

(57) [Claims] The power transmission from an engine is transmitted to a continuously variable transmission (1) capable of steplessly shifting between a neutral position where transmission is not performed and a predetermined maximum speed position, and wherein the stepless transmission is performed. Dress
(1) The lower power transmission system is branched in parallel into two systems, and a forward clutch (FC) and a reverse power are transmitted to each of the two branched transmission systems. And a reverse clutch (RC) for transmitting the power from the forward and reverse clutches (FC), (RC).
4) to form a traveling transmission system, and when the artificially operated speed change operation tool (51) is operated from the neutral position (N) to a high speed side of forward movement, the forward clutch ( FC) is operated and the reverse clutch (RC)
Is operated so that the continuously variable transmission (1) is operated from the neutral position to the high speed side, and the speed change operation tool (51) is operated from the neutral position (N) to the reverse high speed side. The speed change is performed such that the forward clutch (FC) is disengaged and the reverse clutch (RC) is engaged, and the continuously variable transmission (1) is operated from a neutral position to a high speed side. An operation tool (51) and a continuously variable transmission (1),
First linking means for linking forward and reverse clutches (FC) and (RC); and when the shift operation tool (51) is operated to the neutral position (N), the forward clutch (FC) and the reverse clutch (R).
C), so that the continuously variable transmission (1) is operated to the neutral position so as to operate both of them.
And continuously variable transmission (1), forward and reverse clutch (F
C) A traveling transmission structure for a working vehicle, comprising: a second linking means for linking (RC).