JPH0571820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a transmission device for an agricultural tractor or the like that can perform a speed change operation without stopping the vehicle.

BACKGROUND OF THE INVENTION Conventionally, there has been a demand for a transmission device for an agricultural tractor or the like that has a large number of gears and can perform a gear change operation without stopping the vehicle during operation.

One of the typical transmission devices that satisfies this demand is the one described in Japanese Patent Application Laid-open No. 140941/1983. That is, in the power transmission path from the engine to the drive section, transmission gears with different transmission ratios are separately provided on two systems of countershafts, and a clutch is interposed in the input section of each countershaft. When changing gears, one clutch is gradually disengaged to become a half-clutch state, and at the same time, the other clutch is gradually connected to become a half-clutch state. When the rotational displacements of both clutches match, the power transmission path is smoothly shifted to one of the clutches. The speed is changed by converting from one counter shaft to the other counter shaft.

Problems to be Solved by the Invention In order to appropriately control both clutches so that one clutch is gradually disengaged and the other clutch is gradually engaged at the same time, a complicated control mechanism is required. Each time, both clutches become half-clutched, which has the disadvantage that the durability of the clutches is significantly reduced.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a transmission device that can simplify the control of the clutch during gear shifting and improve the durability of the clutch.

Means for solving the problem A first countershaft 20 is connected to the engine 1 via a first clutch 10, and a second countershaft 21 is connected to the engine 1 via a second clutch 11. and an output shaft 19 to which a plurality of passive gears 51 to 54 are fixed are provided in parallel, and a plurality of loosely fitted gears 35 to 38, 44 to 47 and these loosely fitted gears 35 to 38, 44 to 47 are connected. The counter shaft 20,2
Synchronous mesh mechanism 3 selectively connected to 1
Two speed change gear trains 41 and 50 of the same structure consisting of 9, 40, 48, and 49 are provided, the first speed change gear train 41 is provided on the first counter shaft 20, and the second speed change gear train 50 is installed on the second The first transmission gear train 4 is provided on the counter shaft 21 of the
One loose fit gear 35 to 38 of the first transmission gear train 50 and one loose fit gear 44 to 47 of the second transmission gear train 50 are meshed, and the second clutch 11 and the second counter shaft 21 are engaged with each other.
A one-way clutch 42 for transmitting only the power from the clutch 11 side to the counter shaft 21 side is provided between the clutch 11 side and the counter shaft 21 side.

Function During normal work, both counter shafts 20, 2
Power is transmitted to the output shaft 19 through the transmission gear train 41, 50 of the clutch 10, 11, and when shifting, one clutch 10, 11 is disengaged and the transmission gear train 41, 50 on the side of the clutch 10, 11 performs the transmission. At the same time, power transmission continues via the transmission gear train 50, 41 of the other clutch 11, 10, and after the transmission operation is completed, the clutches 10, 11 are connected again to bring both clutches 10, 11 into the connected state, and one-way transmission is performed. The power that has passed through the transmission gear train 41, 50 on the side where the transmission operation was performed by the action of the clutch 42 is transferred to the output shaft 19.
to communicate.

Embodiment An embodiment of the present invention will be described based on the drawings.
The power transmission mechanism of the tractor includes an engine 1, a clutch 2, a main transmission 3, an auxiliary transmission 4, a final reduction gear 5, and drive wheels 6. The crankshaft 7 of the engine 1 is connected via the flywheel 8.
It is connected to the PTO transmission shaft 9 and the clutch 2.
The clutch 2 consists of a first clutch 10 and a second clutch 11, which are arranged in the front and rear, and which independently engage and separate from the flywheel 8, and these clutches 10 and 11 are the same as the PTO transmission shaft 9. It is connected to a first input shaft 12 and a second input shaft 13, which are externally fitted with their axes. The first clutch 10 and input shaft 12 and the second clutch 11 and input shaft 13 are housed in a clutch case 14, and a transmission case 15 housing the main transmission 3 is connected to the clutch case 14. Fixed.

First, the main transmission 3 will be explained. The input shafts 12 and 13 each extend into the transmission case 15, and two fixed output gears 16 and 17 are formed at the end of the first input shaft 12, and the end of the second input shaft 13 is formed with two fixed output gears 16 and 17. A solid output gear 18 is formed in the portion. The transmission case 15 has an output shaft 19 externally fitted onto the PTO shaft 9, a first counter shaft 20, and a second counter shaft 21, with the output shaft 19 at the apex, as shown in FIG. They are built in parallel in a triangular shape. A sleeve 22 and a needle bearing 23 are provided at the front of the counter shaft 20.
Forward input gear 24 and reverse input gear 2
5 are loosely fitted, the forward input gear 24 meshes with the output gear 16, and the reverse input gear 25 meshes with the output gear 17 via an idler gear 26. The forward input gear 24 and the reverse input gear 25 are connected to the synchronizer hub 2.
7, a sleeve 28, a synchronizer pin 29, a synchronizer ring 30, an outer ring 31, and the like.

On the first countershaft 20, a loosely fitted gear 35 for the first speed and a loosely fitted gear 3 for the second speed are provided via a sleeve 33 and a needle bearing 34, respectively.
6. A loose fit gear 37 for third speed and a loose fit gear 38 for fourth speed are loosely fitted, and each loose fit gear 35, 36, 3
7 and 38 are selectively connected to the counter shaft 20 by synchromesh mechanisms 39 and 40 having the same structure as the synchromesh mechanism 32. And these loosely fitted gears 35, 36, 37, 38
A first transmission gear train 41 is constituted by the synchromesh mechanisms 39 and 40.

An input gear 43 is fixed to the front end of the second counter shaft 21 via a one-way clutch 42, and this input gear 43 meshes with the output gear 18. Note that the one-way clutch 42 is connected to the input gear 4.
3 to the second counter shaft 21, and has a structure that does not transmit the rotation of the second counter shaft 21 to the input gear 43. That is, power is transmitted only when the rotation of the input gear 43 is faster than the rotation of the counter shaft 21, and when the rotation of the input gear 43 is slower than the rotation of the counter shaft 21, the power is transmitted through the one-way clutch 42. Not done. Further, on the second counter shaft 21, the first speed change gear train 41 is formed of loosely fitted gears 44, 45, 46, 47 and synchronized mesh mechanisms 48, 49.
A second transmission gear train 50 having the same structure is provided.

The output shaft 19 has the loosely fitted gears 35 and 44.
a first speed passive gear 51 that meshes with the loose fit gears 36, 45, a second speed passive gear 52 that meshes with the loose fit gears 36, 45, a third speed passive gear 53 that meshes with the loose fit gears 37, 46; A fourth-speed passive gear 54 that meshes with the loosely fitted gears 38 and 47 is formed. Note that the two loose-fit gears that mesh with one passive gear, that is, the loose-fit gears 35, 44, the loose-fit gears 36, 45, the loose-fit gears 37, 46, and the loose-fit gears 38, 47, have the same number of teeth. , are the same module, and when the rotation speed of the engine 1 is the same, for example, the rotation speed transmitted to the output shaft 19 via the loose fit gear 35 and the rotation speed transmitted to the output shaft 19 via the loose fit gear 44. The number of rotations is the same.

Next, the sub-transmission device 4 and the final reduction gear device 5 will be explained. The output shaft 19 extends rearward and serves as an input shaft for the sub-transmission device 4, to which a high-speed drive gear 55 and a medium-speed drive gear 56 are fixed, and two idle gears 57 and 58 are loosely fitted therein. ing. A pinion shaft 5 is connected in parallel with the output shaft 19.
A passive gear 60 that meshes with the high-speed drive gear 55 and a passive gear 61 that meshes with the medium-speed drive gear 56 are loosely fitted to the pinion shaft 59. Further, the passive gear 61 is connected to a low speed passive gear 62 loosely fitted onto the pinion shaft 59 via the idle gear 57.
2 is connected to the pinion shaft 5 via the idle gear 58.
It is connected to a very low speed passive gear 63 that is loosely fitted onto the gear 9. And these passive gears 60, 6
1, 62 and 63 are selectively connected to the pinion shaft 59 via clutch gears 64 and 65.

A bevel pinion 66 is provided at the rear end of the pinion shaft 59, and a bevel gear 67 constituting a part of a differential gear meshes with the bevel pinion 66. Furthermore, the bevel gear 67 is connected to the axle 70 via final reduction gears 68 and 69,
The drive wheel 6 is attached to the drive wheel 0.

In such a configuration, the starting operation from the first speed and the running state at the first speed will be explained first. First clutch 10 and second clutch 11
Start engine 1 with the power off. An actuator (not shown) moves the sleeves 28 of the synchronized mesh mechanisms 39, 48 toward the loosely fitted gears 35, 44 via an after fork (not shown) in response to a command signal for running in the first speed. 35 is connected to the first counter shaft 20, and a loose fit gear 44 is connected to the second counter shaft 21. Note that the sleeve 28 of the synchromesh mechanism 32 is connected to the forward input gear 24.
By moving to the side, the forward input gear 24 and the first counter shaft 20 are connected, and the passive gears 60, 61, 62, 6 are also connected in the sub-transmission device 4.
3 is connected to the pinion shaft 59 by clutch gears 64 and 65. If both clutches 10 and 11 are connected at the same time in this state, the power from the engine 1 will be transferred to the clutches 10 and 11.
Input shaft 12, output gear 16, forward input gear 2
4, synchronized mesh mechanism 32, first counter shaft 20, synchronized mesh mechanism 39, loose fit gear 3
5, a power transmission path consisting of a clutch 11, an input shaft 13, an output gear 18, an input gear 43, a one-way clutch 42, a second counter shaft 21, a synchromesh mechanism 48, and a loose fit gear 44. Passive gear 5 passes through two power transmission paths with
1 to the output shaft 19, and is further transmitted to the drive wheels 6 via the sub-transmission device 4 and the final reduction gear device 5. In this way, the vehicle can start from the first speed and run in the first speed. Incidentally, by operating the synchromesh mechanisms 39, 48 to connect the loosely fitted gears 36, 45 to the first and second counter shafts 20, 21, the vehicle can start and travel in the second speed.
The same applies to the third and fourth speeds. In addition, in the auxiliary transmission 4, by selectively meshing the clutch gears 64, 65 with the passive gears 60, 61, 62, 63, high-speed, medium-speed , low speed and very low speed gears are obtained.

Next, a description will be given of when the vehicle moves backward. The reverse input gear 25 is connected to the first counter shaft 20 by the synchromesh mechanism 32, and the first clutch 10
and at the same time, disengage the second clutch 11.
As a result, power is transmitted from the engine 1 through the first transmission gear train 41, and by operating the synchromesh mechanisms 39 and 40, the gears can be changed from 1st reverse speed to 4th rear speed.

Next, regarding shift up from 1st gear to 2nd gear.
The explanation will be given using an example of shifting to a higher speed. First, when driving in first gear, clutches 10 and 11 are connected,
The loosely fitted gears 35 and 44 are connected to the counter shaft 20, respectively.
It is connected to 21. When a shift instruction signal to the second speed is issued while driving in this state, the first clutch 10 is disengaged while the second clutch 11 remains connected, and then the sleeve 28 of the synchromesh mechanism 39 is released. By moving to the fitted gear 36 side, the rotational speed of the loosely fitted gear 36 on the driven side is synchronized with the rotational speed of the first counter shaft 20 on the driving side due to the action of the synchromesh mechanism 39. ,
A mating connection is made. Then, the first clutch 10 is connected. As a result, the power from the engine 1 is initially transmitted from both countershafts 29 and 21 to the output shaft 19, but the power is transmitted through the first countershaft 20 and the loosely fitted gear 36, etc. The rotational speed of the shaft 19 increases from when running in the first speed, and the rotational speed of the second counter shaft 21 connected to the output shaft 19 via the passive gear 51, the loose fit gear 44, and the synchromesh mechanism 48 increases to the second speed. Second clutch 1
The rotation speed of the input gear 43 connected to the input gear 43 increases. Therefore, the one-way clutch 42 disconnects the power transmission between the input gear 43 and the counter shaft 21, and the counter shaft 21 becomes idle. From this state, the second clutch 13 is disengaged, the sleeve 28 of the synchromesh mechanism 48 is moved toward the loose fit gear 45, and the loose fit gear 45 is connected to the second counter shaft 21 via the synchromesh mechanism 48. do. Then, by connecting the second clutch 13, power is transmitted from the engine 1 to the output shaft 19 through two power transmission paths: the first countershaft 20 side and the second countershaft 21 side. The shift up to 2nd gear is now complete.

Next, regarding downshifting, shift from 4th gear to 3rd gear.
The explanation will be given using an example of shifting to a higher speed. When traveling in the fourth speed, the loosely fitted gears 38 and 47 are connected to the counter shafts 20 and 47 by the synchromesh mechanisms 40 and 49, respectively.
21 and the first and second clutches 10, 11 are connected thereto. If a shift instruction signal to 3rd gear is issued while driving in this state,
First, the second clutch 11 is disengaged, and then the sleeve 28 of the synchromesh mechanism 49 is moved toward the loose fit gear 46 to connect the loose fit gear 46 and the second counter shaft 21. Then, the second clutch 11 is connected. Then, similarly to the shift from the first speed to the second speed, the loosely fitted gear 3
Due to power transmission from the 8th side to the output shaft 19, the rotation speed of the second counter shaft 21, which is connected to the output shaft 19 via the loosely fitted gear 46, increases when running in the 4th speed, and the one-way clutch is activated. 42 causes the counter shaft 21 to idle. Then, when the first clutch 10 is disengaged, power transmission to the first countershaft 20 is cut off, and the rotation of the second countershaft 21 is reduced. When this rotation decreases to a predetermined value, power is transmitted from the engine 1 to the output shaft 19 via the one-way clutch 42, the second counter shaft 21, and the like. And synchronized mesh mechanism 4
0 sleeve 28 to the loosely fitted gear 37 side to connect the loosely fitted gear 37 and the first counter shaft 20,
By connecting the first clutch 10, power is transmitted from the engine 1 to the output shaft 19 through two power transmission paths: the first countershaft 20 side and the second countershaft 21 side. , 3rd
The downshift to high speed is completed.

In addition, the clutches 10, 11 and the synchronized mesh mechanism 39,
A series of operations 40, 48, and 49 are sequentially and automatically performed by the actuator in response to a signal from the control device based on the driver's gear change instruction operation.

Effects of the Invention As described above, the present invention can perform gear shifting by sequentially and independently connecting and disconnecting the first clutch and the second clutch, and therefore,
The clutch connection/disconnection control device can be made simple, and even when one clutch is disengaged, power is reliably transmitted from the other clutch side, ensuring that the aircraft stops traveling when changing gears. In addition, during gear shifting, there is no need to maintain the half-clutch state until the rotational speeds of the two counter shafts match due to the action of the one-way clutch, and the half-clutch state of the clutch is extremely short. This has the effect of improving the durability of the clutch.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view, FIG. 2 is an explanatory diagram showing a simplified power transmission path, and FIG. 3 is a longitudinal sectional side view. 1...Engine, 10-11...Clutch, 19...
Output axis, 20, 21...Counter axis, 35-38...
Loose fitting gear, 39-40... synchronized mesh mechanism,
41... Speed change gear train, 42... One-way clutch, 44
~47... Loose fit gear, 48, 49... Synchronous mesh mechanism, 50... Speed change gear train, 51-54... Passive gear.

Claims (1)

[Claims] 1 a first countershaft coupled to the engine via a first clutch; a second countershaft coupled to the engine via a second clutch;
An output shaft to which a plurality of passive gears are fixedly installed is provided in parallel, a plurality of loosely fitting gears are loosely fitted to the first countershaft, and these loosely fitting gears are selected as the first countershaft. A first speed change gear train consisting of a synchronized mesh mechanism is provided on the first counter shaft, and a second speed change gear train having the same structure as this first speed change gear train is provided on the second speed change gear train. the second clutch and the second counter; A transmission characterized in that a one-way clutch is provided between the shaft and the one-way clutch for transmitting only power from the second clutch side to the second countershaft side.