JPH01233120A - Speed change structure for working vehicle - Google Patents

Abstract

PURPOSE:To facilitate the speed change operation for advance/retreat and improve the durability of a hydraulic clutch by installing a speed change mechanism for advance/retreat which selects the advance and retreat by the selection of turning-ON/OFF of a pair of hydraulic clutches and using one of the hydraulic clutches as a hydraulic clutch for speed change. CONSTITUTION:Inside a transmission case M, a main gear speed change mechanism H1 is installed over an input shaft 1 connected with an engine E and the first transmission shaft 2 for traveling. The advance/retreat gear speed change mechanism H2 for changing the output of the second transmission shaft 3 between the normal and reverse revolution and the the subgear speed change mechanisms H3 and H4 for selecting the output in two stages are installed. The hydraulic clutches C1 and C2 for advance and retreat are installed onto the advance/retreat gear speed change mechanism H2, and advance or retreat state can be realized by the selection of the hydraulic clutches. By turning-ON /OFF an advance side hydraulic clutch C1 in the speed change operation for the main gear speed change mechanism H1, the use as the speed change hydraulic clutch C is permitted. Further, the hydraulic clutch C2 for retreat can be utilized also as a speed change clutch.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission structure for a working vehicle provided with a hydraulic clutch for transmission that is automatically turned on and off in conjunction with a shift operation to a transmission.

(Prior Art) In the transmission structure of this type of work vehicle, conventionally, the forward/reverse transmission mechanism within the transmission device was manually operated via a manual transmission lever (for example, Utility Model Application No. 62-13773
4 Publication).

[Problem to be solved by the invention]

Such manually operated devices have the disadvantage that as the model gets larger, the transmission torque increases, resulting in the shifter, etc. operated by the gear shifting operation becoming larger, and the operating force increases proportionally. Ta.

In addition, in the conventional configuration, the hydraulic clutch for shifting is a single one, so when the vehicle repeatedly moves forward and backward, the hydraulic clutch for shifting must be engaged and disengaged frequently, so it was necessary to improve the durability of the clutch. .

In other words, taking the case of switching from forward to reverse as an example, it is necessary to disengage the clutch in forward mode, switch from forward mode to reverse, and then engage the clutch, twice for every - shift operation. I was supposed to operate the clutch.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic clutch for shifting with a rational structure, which facilitates forward/reverse shifting operations and improves the durability of the hydraulic clutch.

[Failure to solve the problem]

The characteristic configuration of the present invention is that: (1) a forward/reverse transmission mechanism is provided that switches between forward and reverse by selecting between a pair of hydraulic clutches; (2) one of the forward or reverse hydraulic clutches is also used as the transmission hydraulic clutch; The functions and effects are as follows. .

[For production]

In other words, by focusing on the hydraulic clutch on the forward side from feature configuration ■, it is possible to switch between forward and stop, and by turning on and off the hydraulic clutch on the reverse side, it is possible to switch between forward and stop.
It is possible to switch between stops. Moreover, the feature configuration■
Therefore, by turning on and off the negative hydraulic clutch, it is possible to perform a speed change operation using the hydraulic clutch even in a speed change operation other than forward or backward movement.

〔Effect of the invention〕

Therefore, by adopting a hydraulic clutch for switching between forward and forward movement, it is possible to achieve easier operation than conventional gear shifting operations that rely on manual operating force, and also to make it easier to operate the gears in the transmission case using the operating lever on the hand side. Compared to the conventional configuration in which link mechanisms and the like must be provided up to the shifter, there are fewer restrictions on the arrangement because only the valves and piping for hydraulic control are arranged.

In addition, in the forward/reverse switching operation, when switching from the forward state to the reverse state, the forward-side clutch is simply turned off and the reverse-side clutch is turned on, so each of the forward/reverse clutches only needs to be operated - times. Not done. therefore,
The number of actuations of the hydraulic clutch can be reduced by one, and even if the same strength structure is adopted, the service life can be extended.

〔Example〕

Fig. 2 shows the transmission structure inside the transmission case (M) installed in the tractor, and the transmission structure between the input shaft (1) interlocked with the engine (E) and the first transmission shaft (2) for traveling. Equipped with a synchromesh type main gear transmission mechanism (old) that can freely switch gears, a forward/reverse gear transmission mechanism (H2) that changes the output of the second transmission shaft (3) in forward and reverse directions, and the output from it can be switched to two high and low gears. Flexible synchromesh type 1st sub gear transmission mechanism (H3)
, and a second auxiliary gear transmission mechanism (H4) that can freely switch the output therefrom into two high and low stages, and the output of the second auxiliary gear transmission mechanism (H4) is transferred to the rear wheel (4) differential. Mechanism (4
A) and the operating mechanism (5A) of the front wheel (5).

Here, the main gear transmission mechanism (+11), the forward and reverse gear transmission mechanism (H7), the first gear transmission mechanism (+11), and the first gear transmission mechanism (H7). Second auxiliary gear transmission mechanism (+13).

(H4) is collectively referred to as a transmission (A).

A synchromesh type gear transmission device (1) that changes the power of the input shaft (1) in four stages and transmits it to the power output transmission shaft (6).
7), as well as a transmission shaft (6) and a power take-off shaft (8).
A relay transmission shaft (9) is provided between the power output shaft (8) and the power output shaft (8).

Next, let's look at the speed change operation structure for the driving transmission system.

This will be explained in detail based on FIGS. 1 and 2.

That is, the main gear transmission mechanism (old) has two main gear shifting shift units (IOA) that are selectively operated.

(10B) are interlocked with each other, and two operating hydraulic cylinders (IIA) and (IIB) are attached, and
An operating hydraulic cylinder (13) which is interlockingly connected to a first auxiliary gear shifter (12) to a first auxiliary gear transmission mechanism (H3).
) is attached.

Further, two operating hydraulic cylinders (IIA) and (IIB) for the main gear transmission mechanism (Hl) and the first
Hydraulic cylinder for operating the auxiliary gear transmission mechanism (H3) (
Three 3-position switching valves (S+), (S2) with the piston of 13) also used as a sliding spool.

(S3) is configured.

The operating hydraulic cylinder (11^), (IIB),
The supply of pressure oil to (13) and the three-position switching valves (Sl), (S2), and (Sa) are carried out using a 9-position o-critique type main control valve (V). (
N, Fl-, -Fa) switching valves are operated, and pressure oil is supplied to this 9-position switching valve (vl) from a hydraulic pump (P) via a pressure reducing valve (15).

On the other hand, the forward/reverse gear transmission mechanism (H2) is equipped with a multi-disc friction forward/reverse hydraulic clutch (C+).

(C2) is equipped with these hydraulic clutches (C+),
Depending on the selection of (C2), either forward or forward movement appears. Then, the forward hydraulic clutch (C1) is installed in series with the traveling transmission system, and the main gear transmission mechanism (Hl
), etc., the forward hydraulic clutch (C1)
By turning on and off, it can also be used as a hydraulic clutch for shifting (C).

Further, as shown in FIG. 1, the forward hydraulic clutch (C
1) and the reverse hydraulic clutch (C2), a first forward/reverse switching control valve (vl) and a second forward/backward switching control valve (v3) for important control are provided. The shift hydraulic clutch (C), which is also used in (C1), is driven by hydraulic pressure supplied from the pressure reducing valve (15) via a pressure adjustment mechanism (16), which will be described later. 16) and the hydraulic clutch (C), the pressure oil from the pressure adjustment mechanism (16) is applied to the clutch (C).
Four pilot pressure operated type 2 act as changeover valves (17) that can be selectively switched between a clutch engaged state where pressure oil in the clutch (C) is supplied to the tank (T) and a clutch disengaged state where pressure oil in the clutch (C) is returned to the tank (T). Position switching valve (17A), (17B),
(17c).

(170) are connected in series, one of which is a pilot pressure-operated two-position switching valve (17A), which is connected in parallel to the main control valve (vl) as a first forward/reverse switching control valve. The remaining three pilot pressure operated two-position switching valves (17B) are operated by pressure oil supplied from the valve (vl).
, (17C), and (170) are operated by pressure oil supplied from the three-position switching valves (s+), (S2), and (S3), respectively, and are thereby operated by the main gear transmission mechanism (H
l), only when the forward/reverse gear transmission mechanism (H2) and the first auxiliary gear transmission (H3) are all in the transmission state,
4 pilot pressure operated 2 position switching valves (17A),
When all of (17B), (17C), and (170) are switched to a communicating state, the clutch is engaged, and the clutch (C) is automatically switched in accordance with the gear shift operation. There is.

Further, a branch oil path (b) for supplying oil to the reverse hydraulic clutch (C2) is connected to a second forward/reverse switching control valve from a pressure oil path between the switching valve (17) and the forward hydraulic clutch (C1). (
v3), and the second forward/reverse switching control valve (v3) is connected to the first forward/reverse switching control valve (vl).
) is provided with a pilot operating oil passage (C), and when the first forward/reverse switching control valve (vl) is switched to the reverse side, the pilot pressure acts on the second forward/reverse switching control valve (v3) and the second
Forward/forward switching control valve (V3) Hydraulic clutch for reverse (C2)
Switch the state of refueling. Here, when the first forward/reverse switching control valve (vl) is switched to the forward side and the pilot pressure is released, the second forward/reverse switching control valve (v3) is returned to the state of supplying oil to the forward hydraulic clutch (C1). Can be done.

In addition, the two hydraulic cylinders (I) of the main gear transmission mechanism (■1)
IA) (IIB) (IIB) When one of the hydraulic cylinders is operated to the shifting side, the other hydraulic cylinder is operated and held in a neutral position by pressure oil.

Further, the second auxiliary gear transmission mechanism (4) is provided with a shifter that can be operated with a speed change lever. Furthermore, the transmission device (7) relative to the power take-off shaft (8) is configured to be manually operated.

In the figure, (N) and (Fl) to (F8) each indicate the operating position of the main control valve (vl), and (F) and (R)
indicates the operating position of the first forward/reverse switching control valve (ν2),
(H) and (L) indicate the operating positions of the 3-position switching valve (S3) for the first auxiliary gear transmission.

As shown in FIGS. 1 and 2, the pressure adjustment mechanism (1
6) is a low-pass valve mechanism (2o) that is closed by the pilot pressure (Pl) on the secondary side, and a bypass valve mechanism (19) that is opened by the pilot pressure (P2) on the secondary side.
and a throttle mechanism (21) connected in parallel to these valves.
It is composed of.

Here, once the gear shift operation is performed, the hydraulic clutch (C
), the supply starts again, and first, as shown in Fig. 3, the oil from the pump (P) is supplied through the low-pass valve mechanism (20), and as shown in Fig. 3, ,
When the pilot pressure on the secondary side increases to the set pressure (Pl) and the hydraulic clutch (C) becomes a half-clutch state, the low-pass valve mechanism (20) is closed and the oil is transferred to the first throttle mechanism (21).
It is supplied to the hydraulic clutch (C) through. In this half-clutch state, the viroft pressure on the secondary side is the set pressure (P2)
When it increases to , the bypass valve af! (19) is opened, and the oil is introduced into the hydraulic clutch (C), reaching the clutch operating pressure (P3).

[Another example]

(2) The reverse hydraulic clutch (C2) may also be used as the shift hydraulic clutch (C).

(2) The transmission structure as described above may be used in other agricultural vehicles or construction machines other than tractors.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission structure for a work vehicle according to the present invention,
The first is a hydraulic circuit configuration diagram, the second is an overall configuration diagram of the transmission system,
FIG. 3 is a pressure increase characteristic diagram by the pressure adjustment mechanism. (A)...Transmission device, (C)...Hydraulic clutch for shifting, (C,), (cz)...Hydraulic clutch for forward/reverse movement, (11□) ...Forward and backward transmission mechanism.

Claims (1)

[Claims] This is a transmission structure for a work vehicle equipped with a hydraulic clutch for transmission (C) that is automatically turned on and off in conjunction with a shift operation to a transmission (A), and includes a pair of hydraulic clutches (C_1) and (C_
A forward/reverse transmission mechanism (H_2) is provided which switches between forward and reverse by turning on/off one of 2), and one of the forward or reverse hydraulic clutches (C_1 or C_2) is also used as the transmission hydraulic clutch (C). The transmission structure of a working vehicle.