JP3537848B2 - Hydraulic transmission operation device for traveling vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shift operation device for a traveling vehicle such as a tractor.

[0002]

2. Description of the Related Art For example, in a tractor, a forward / reverse switching mechanism and a main transmission mechanism of a traveling power transmission system are of a hydraulic clutch switching type, and a hydraulic circuit for operating them is proportional to a forward / backward switching mechanism and a direction switching valve. The main transmission mechanism is connected to a plurality of switching valves for turning on and off the supply of pressure oil.All of these valves adopt solenoid valves and operate as an operation lever or operation switch. It can be operated by the speed change operation means.

The forward / reverse switching mechanism also functions as a substitute for the main clutch of the tractor, is connected with an electromagnetic proportional valve to obtain a half-clutch state, and the main transmission mechanism can normally shift to three to four speeds. A plurality of solenoid-operated switching valves are provided for selectively obtaining each speed stage number, and these are adapted to supply pressure oil by being excited and to be stopped by being demagnetized.

[0004]

In a tractor, the electric system may be short-circuited for some reason, and when such a short-circuit occurs, the hydraulic clutch remains disconnected and the vehicle travels. It becomes difficult. According to the present invention, the direction switching valve of the forward / reverse switching mechanism has a neutral position and can be manually operated during demagnetization, and the proportional valve of the forward / reverse switching mechanism and one of the switching valves of the main transmission mechanism have reverse characteristics. By using a valve,
It is an object of the present invention to provide a hydraulic shift operation device for a traveling vehicle that is capable of moving a vehicle even when an electric system is short-circuited and maintained in a demagnetized state.

[0005]

A specific means for solving the problems in the present invention is that the forward / reverse switching mechanism 17 and the main transmission mechanism 1 of the traveling power transmission system are of a hydraulic switching type, and the forward / reverse switching mechanism 17 is provided. A hydraulic shift operation device for a traveling vehicle in which a directional switching valve 6 and a proportional valve 7 are connected, a plurality of switching valves 8 for turning on / off the supply of pressure oil to the main transmission mechanism 1 are connected, and all valves are solenoid valves. The direction switching valve 6
Is a valve having a neutral position N and can be manually operated at the time of demagnetization, and the proportional valve 7 and one of the switching valves 8 of the main transmission mechanism are reverse characteristic valves for supplying pressure oil at the time of demagnetization.

[0006]

[Function] The electric system of the traveling vehicle is ground short-circuited.
When the solenoid valve constituting the hydraulic shift operation device is in a demagnetized state, the direction switching valve 6 of the forward / reverse switching mechanism 17 becomes the neutral position N, and the switching valves 8 other than one of the main transmission mechanism 1 stop supplying the hydraulic oil. State.

On the other hand, since the proportional valve 7 of the forward / reverse switching mechanism 17 and the switching valve 8 of one of the main transmission mechanisms 1 have reverse characteristics, the hydraulic oil can be supplied. When operated, it is possible to move the tractor forward or backward.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an example of a tractor transmission. A propulsion shaft 14 is connected to a flywheel 12 connected to a crankshaft of an engine via a buffer 13, and a PTO interlocking shaft 15 is provided at the rear end of the propulsion shaft 14. The PTO power transmission system is configured by spline fitting.

The traveling power transmission system includes a forward / reverse switching mechanism 1
7, a main transmission mechanism 1, a second transmission mechanism 2, a third transmission mechanism 3, and a front wheel drive switching mechanism 18. The forward / reverse switching mechanism 17 is a hydraulic clutch type, and
Front and rear hydraulic clutches 19F, 19R and rear gear 2
0, a front gear 22 provided on a traveling propulsion shaft 21 loosely fitted to the PTO interlocking shaft 15, and a transmission gear 2 provided on a reverse transmission shaft 23.
4, 25, and a back idler gear 26 meshing with the rear gear 20 and the transmission gear 24.

The forward power is transmitted from the propulsion shaft 14 to the traveling propulsion shaft 21 via the front gear 22 by engaging the front hydraulic clutch 19F, and the reverse power is transmitted to the rear hydraulic clutch 19R.
Is transmitted from the rear gear 20 to the traveling propulsion shaft 21 from the front gear 22 via the back idler gear 26 and the transmission gears 24 and 25 of the reverse transmission shaft 23. The main transmission mechanism 1 is of a hydraulic clutch type and has a first speed gear 2 between a traveling propulsion shaft 21 and a counter shaft 28 disposed in parallel with the traveling propulsion shaft 21.
9, 30, second speed gears 31, 32, third speed gears 33, 3
Fourth and fourth speed gears 35 and 36 are disposed, and the first and second speed gears 35 and 36 are provided.
The speed is switched by hydraulic clutches 37A and 37B, and the third speed and the fourth speed can be switched by hydraulic clutches 38A and 38B.
By selecting and connecting one of the first to fourth speeds via 38, the power of the traveling propulsion shaft 21 is transmitted to the counter shaft 28.

The second speed change mechanism 2 is of a synchromesh (mechanical) type which is switched by sliding a shift gear 41 by a shifter 40, and is concentric with a gear 42 provided at the rear end of the counter shaft 28 behind the counter shaft 28. , And gears 46 and 47 on a gear transmission 45 that is loosely fitted to the PTO interlocking shaft 15. The shift gear 41 is slid to move the counter shaft 28 and the transmission shaft 43. And the high speed power is transmitted to the transmission shaft 43, and the low speed is transmitted from the counter shaft 28 via the gear 42, the gears 46 and 47 on the gear transmission 45, and the gear 44 on the transmission shaft 43. The power is transmitted to the transmission shaft 43.

The third transmission mechanism 3 is of a mechanical type which is switched by sliding a shift gear 51 by a shifter 50, and includes a gear 52 provided at a rear end of a transmission shaft 43 and a transmission shaft 43.
A gear 54 on a bevel pinion shaft 53 and a gear 56, 57 on an idler shaft 55, which are arranged concentrically behind the
By sliding the shift gear 51 to directly connect the transmission shaft 43 and the bevel pinion shaft 53, high-speed power is transmitted to the bevel pinion shaft 53, and the transmission shaft 43 transmits the gear 52 and the gears 56 and 57 on the idler shaft 55. And bevel pinion shaft 5
The low-speed power is transmitted to the bevel pinion shaft 53 via the gear 54 on the third gear 3.

The third speed change mechanism 3 is also of a synchromesh (mechanical) type. The shifter 50 is provided so as to be able to move integrally with a shifter shaft 67, and both ends of the shifter shaft 67 are provided with pistons in left and right cylinders 68A and 68B. Power shift type (shifter hydraulically movable structure) in which the shifter 50 is slid hydraulically to switch the third transmission mechanism 3 to a high or low position by selectively supplying pressure oil to the left and right cylinders 68A and 68B. )It has become.

The power from the bevel pinion shaft 53 is
The power is transmitted to the rear wheels via the rear wheel differential mechanism, and the gear 6
0, 61 to the front first transmission shaft 62, and from the front first transmission shaft 62 by the front wheel drive switching mechanism 18
The power is transmitted to the front second transmission shaft 63 in three modes: a front wheel non-drive mode, a front wheel constant speed mode, and a front wheel double speed mode, and is transmitted from the front second transmission shaft 63 to the front wheels via a front wheel differential mechanism. .

In FIG. 1 and FIG. 2, a hydraulic shift operation device includes a hydraulic pump 71 and hydraulic clutches 19, 37, 38 of the forward / reverse switching mechanism 17, the main transmission mechanism 1 and the third transmission mechanism 3 from the hydraulic pump 71. The hydraulic circuit 72 includes a hydraulic circuit 72 that supplies pressure oil to the cylinder 68, and a controller (not shown) that controls all solenoid valves provided in the hydraulic circuit 72.

The hydraulic clutch 1 of the forward / reverse switching mechanism 17
9F and 19R have electromagnetic directional switching valve 6 and proportional valve 7
The direction switching valve 6 has a neutral position N at the center, and is energized to excite the hydraulic clutch 19F,
It is switchable to supply pressure oil alternatively to 19R, is located at the neutral position N when demagnetized, and is provided so that it can be switched manually.

The electromagnetic proportional valve 7 controls the hydraulic oil supply amount so that the hydraulic clutches 19F and 19R can be brought into a half-clutch state.
Can be used as the main clutch of the tractor. The proportional valve 7 is a reverse characteristic valve that supplies pressure oil at the time of demagnetization. The main transmission mechanism 1 has four hydraulic clutches 37.
A, 37B, 38A, 38B, respectively, electromagnetic switching valves 8A, 8B, which turn on / off the supply of pressure oil,
8C and 8D are connected, and the switching valve 8 for the second to fourth speeds is connected.
B, 8C and 8D are positive characteristic valves, and only the first speed switching valve 8A is a reverse characteristic valve for supplying pressure oil at the time of demagnetization.

The third transmission mechanism 3 includes cylinders 68A, 68
An electromagnetic directional switching valve 73 is connected to B, so that it always enters one of high and low. In the above-described embodiment, the direction switching valve 6 of the forward / reverse switching mechanism 17 is energized to enter the forward or backward direction from the neutral position N, the proportional valve 7 is demagnetized, and the switching valve 8A of the switching valve 8 is demagnetized. Alternatively, one of the switching valves 8B to 8D is excited, and the switching valve 73 is excited or demagnetized to travel the tractor.

If a short circuit occurs due to some failure in the tractor's electric system, the directional control valve 6 is set to the neutral position N.
Then, the proportional valve 7 and the switching valve 8A are maintained in a state in which the pressure oil can be supplied by demagnetization, the switching valves 8B to 8D are maintained in a state in which the pressure oil is stopped, and the switching valve 73 is in either the high or low state. In this state, when the direction switching valve 6 is manually operated forward or backward, the pressure oil from the hydraulic pump 71 is supplied to one of the hydraulic clutches 19F and 19R via the proportional valve 7 and the direction switching valve 6, and the switching valve 8A
Is supplied to the hydraulic clutch 37A via the switching valve 73 and to the cylinder 68B via the switching valve 73, so that the tractor can travel.

In most cases, the short circuit of the electric system of the tractor is a ground short, but a plus short may occur. In the case of a plus short, the harness connected to the proportional valve 7 and the switching valves 8B to 8D are connected. My 2
Disconnecting the harness of the two valves allows the tractor to travel. Further, the present invention is not limited to the above-described embodiment, and can be variously modified. For example, the second speed change mechanism 2 may be a hydraulic clutch type, and the third speed change mechanism 3 may be a power shift type. However, the third speed change mechanism 3 may be a mechanical type or a hydraulic clutch type, and the switching valve 73 has a neutral position N and is manually demagnetized. An operable valve may be used, and instead of the switching valve 8A, any of the switching valves 8B to 8D may be a reverse characteristic valve.

[0021]

According to the present invention described in detail above, the direction switching valve 6 for the forward / reverse switching mechanism 17 has a neutral position N and can be manually operated at the time of demagnetization. Since the proportional valve 7 for 17 and one of the switching valves 8 of the main transmission mechanism are reverse-characteristic valves that supply pressure oil when demagnetized, the electric system of the traveling vehicle is short-circuited and all the solenoid valves are maintained in the demagnetized state. However, the main speed change mechanism 1 is in one speed state, and the forward / reverse switching mechanism 17 can be manually turned on, thereby enabling the tractor to move.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing one example of a transmission to which the present invention can be applied.

[Explanation of symbols]

1 Main transmission mechanism 2 Second transmission mechanism 3 Third transmission mechanism 5 Speed change mechanism 6 Direction switching valve 7 Proportional valve 8 Switching valve 17 Forward / backward switching mechanism 19 Hydraulic clutch 71 Hydraulic pump 72 Hydraulic circuit N neutral position

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-243553 (JP, A) JP-A-61-130650 (JP, A) JP-A-61-105337 (JP, A) JP-A-4- 327062 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 61/12 B60K 17/06

Claims (1)

(57) [Claims] 1. A forward / reverse switching mechanism (17) and a main transmission mechanism (1) of a traveling power transmission system are of a hydraulic switching type,
A direction switching valve (6) and a proportional valve (7) are connected to the forward / reverse switching mechanism (17), and a plurality of switching valves (8) for turning on / off the supply of pressure oil are connected to the main transmission mechanism (1). A hydraulic shift operation device for a traveling vehicle in which all valves are solenoid valves, wherein the direction switching valve (6) is a valve having a neutral position (N) and manually operable during demagnetization; And a switching valve (8) of (1) of the main transmission mechanism is an inverse characteristic valve for supplying pressure oil at the time of demagnetization.