JPH0526686B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission structure for a work vehicle equipped with two or more sets of gear change type transmissions, such as a main transmission and a sub-transmission.

[Conventional technology]

The transmission structure of an agricultural tractor, which is an example of a working vehicle equipped with two sets of gear-shifting transmissions, includes:
There is a structure in which a main transmission with three forward speeds and one reverse speed and an auxiliary transmission with two high and low speed speeds are connected in series. The shift pattern in this structure is shown in Figure 4.
An auxiliary lever guide 36 for the auxiliary transmission having two high and low positions H and L, and a main lever for the main transmission having three forward speed positions F ₁ , F ₂ , F ₃ and one reverse R position. This is done by operating the sub-shift lever 38 and the main shift lever 39 along the guide 37. As a result, 6 forward speeds,
A two-speed reverse gear shift state is obtained.

[Problems to be Solved by the Invention] In recent years, with the diversification of work situations, situations have arisen that cannot be handled by the number of shift states mentioned above, so one more gear shift state has been added to the main gear shift device as shown in Figure 5. There is a structure that adds a position F ₄ , and it is possible to obtain eight forward gears, but it is difficult to quickly shift from the F ₄ position to the R position.
This results in a configuration with somewhat poor operability.

Therefore, in recent years, a configuration in which a forward/reverse switching device is combined with the configuration shown in FIG. 4 has appeared. This results in a shift pattern as shown in Figure 6, with 8 forward and 8 reverse gears, and it also makes switching between forward and backward gears easier, but it tends to complicate the structure and increase manufacturing costs. .

An object of the present invention is to obtain a transmission structure that can increase the number of gears and facilitate forward/forward switching while suppressing the complexity of the structure.

[Means for solving problems]

The feature of the present invention is that in the transmission structure of the work vehicle mentioned above, there are three states: forward high speed, forward low speed, and reverse state.
A first variable transmission device that is switched between two positions by linearly operating one shift member, and a second transmission device that is configured to be able to shift between three or more positions are connected in series. The functions and effects are as follows.

[Operation] With the configuration as described above, even when the second transmission is in a certain position and the first transmission is in the forward high speed or low forward speed position and the vehicle is moving forward, the shift member can be operated linearly to easily shift to the reverse position. Can be switched. Furthermore, even if the number of gears of the second transmission device is increased, the ease of switching to the reverse state is not impaired.

〔Effect of the invention〕

As described above, by using a special device such as a forward/reverse switching device, a structure has been created that can improve the ease of switching to reverse and also increase the number of gears, thereby reducing manufacturing costs. It was possible to improve the shift operability of the work vehicle while suppressing the rise and complexity of the structure.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows the transmission structure of an agricultural tractor. Power from the engine (not shown) is first input to the input shaft 1.
and is transmitted to the first electric shaft 2 by gear transmission. A second power transmission shaft 3 is arranged concentrically with the input shaft 1 and relatively rotatable,
A shift member 4 is attached to the second transmission shaft 3 so as to be slidable and integrally rotatable with a spline structure, and a second reverse gear 5 and a second high speed gear 6 are mounted on both sides of the shift member 4. is fitted loosely.

Further, a first reverse gear 7 that meshes with the second reverse gear 5 via an induction gear 5A is fixed to the first transmission shaft 2, and a first reverse gear 7 that meshes with the second high speed gear 6 is fixed to the first transmission shaft 2. 1. A high speed gear 8 and a low speed gear 9 are fixed. FIG. 1 shows a state in which the shift member 4 is engaged with the low-speed gear 9, and the engine power is transmitted from the first transmission shaft 2 to the low-speed gear 9 and then to the second transmission shaft at a forward low speed L via the shift member 4. transmitted to 3,
It is transmitted from the second power transmission shaft 3 to a second variable device 11 on the downstream side, which will be described later.

Then, when the shift member 4 is moved linearly by the first shift lever 31 and engaged with the second high speed gear 6, the power is transmitted to the second transmission 11 in the state of forward high speed H, and the shift member 4 is moved to the second reverse gear. When the gear 5 is engaged, power is transmitted to the second transmission 11 in the reverse state R. As mentioned above, forward high speed/low speed H, L
The first transmission 10 is configured to be able to shift to three positions: and a reverse state R.

Next, the second transmission 11 that receives the power from the first transmission 10, performs a four-speed gear shifting operation, and transmits it to the rear wheel differential mechanism 12 will be described in detail.
As shown in FIG. 1, a third transmission shaft 13 is arranged concentrically with the first transmission shaft 2 and relatively rotatable. On this third transmission shaft 13, driven 1st and 2nd speed gears 14 and 15 are fitted in reverse order, and driven 3rd and 4th speed gears 16 and 17 are fixed, and the driven 1st and 2nd speed gears 16 and 17 are fixed.
Drive 1st and 2nd speed gears 18 and 19 that mesh with 2nd speed gears 14 and 15 are fixed to the second transmission shaft 3, and drive 3 that meshes with the driven 3rd and 4th speed gears 16 and 17.
The speed and fourth speed gears 20 and 21 are fitted loosely.

A shift member 22 is attached between the driven 1st speed and 2nd speed gears 14 and 15 with a spline structure so that it can slide and rotate integrally with respect to the third transmission shaft 13. - By selectively engaging the second gears 14 and 15, first and second gear shifting states can be obtained. Also, drive 3
A shift member 23 is also attached between the 3rd and 4th gears 20 and 21 with a spline structure so that it can slide and rotate integrally with the second transmission shaft 3, and this shift member 23 drives the 3rd and 4th gears 20. .

The power from the first transmission 10 is transmitted to a rear mount type working device (not shown) and a mid mount type working device (not shown) via a rear PTO shaft 24 and a mid PTO shaft 25. ,
To explain its structure in detail, as shown in FIG.
PTO shafts 24 are arranged in parallel, and this rear PTO shaft 2
4 is a first rear gear that engages with the first reverse gear 7;
The PTO gear 26 is freely fitted on the outside, and the first shift member 27 has a spline structure so that it can slide relative to the rear PTO shaft 24 and rotate integrally with the first shift member 27.
is installed. By operating this first shift member 27 and engaging it with the first rear PTO 26 or the low-speed gear 9, a two-speed gear change operation can be performed, and power can be transmitted to a rear-mounted working device. .

Furthermore, a first mid-PTO gear 28 that meshes with the first high-speed gear 8 is fitted onto the rear PTO shaft 24 with free rotation, and a second shift member 29 is fitted onto the rear PTO shaft 24 with free rotation. Then, this second shift member 29
meshes with the second mid-PTO gear 30, and the second mid-PTO gear 30 engages with the gear portion 2 of the mid-PTO shaft 25.
It is interlocking with 5a. In other words, the second
By engaging the shift member 29 with the first mid-PTO gear 28, the first high-speed gear
It turns on/off power transmission to the PTO shaft 25.

The shift pattern in the transmission configured as described above is as shown in FIG.
The lever guide 32 is configured linearly and linearly operates the first shift lever 31 into three positions: forward high speed H, forward low speed L, and reverse state R. The second lever guide 34 of the second shift lever 33 for operating the second transmission 11 is configured in an H-shape, and the second shift lever 33 is set to 1st gear (F 1 ), 2nd gear (F ₁ ), 2nd gear, etc.
It operates in four positions: speed (F ₂ ), 3rd speed (F ₃ ), and 4th speed (F ₄ ). In this way, a total of eight forward speeds and four reverse speeds can be achieved.

It is also possible to have a structure in which the mid PTO shaft 25 is not attached, and the second mid PTO shaft 25 is not attached as shown in Fig. 3.
At the same time as removing the PTO gear 30 and the mid PTO shaft 25, the second rear PTO gear 35 that engages with the first high speed gear 8 is freely fitted onto the rear PTO shaft 24, and the first shift member 27 is connected to the first rear PTO shaft. By engaging the gear 26, the low-speed gear 9, and the second rear PTO gear 35, it is possible to perform a three-speed gear change operation of high, medium, and low, and to transmit power to the rear-mounted working device.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission structure of a working vehicle according to the present invention, and FIG. 1 is a sectional view showing the transmission structure with a mid PTO shaft attached, and FIG. 2 is a sectional view showing a shift pattern. A plan view of the two-lever guide, FIG. 3 is a sectional view showing the transmission structure without the mid-PTO shaft installed, and FIGS. 4, 5, and 6 are plan views of shift patterns showing conventional and comparative examples of the present invention. It is a diagram. 4...Shift member, 10...First transmission, 1
1...Second transmission, H...High speed forward, L...Low speed forward, R...Reverse state.

Claims (1)

[Claims] 1. A first transmission 10 that is operated by linearly operating one shift member 4 to three positions: forward high speed H, forward low speed L, and reverse state R; A transmission structure of a working vehicle in which a second transmission device 11 configured to be able to change speeds is connected and arranged in series.