JPH06298054A - Parking brake device for traveling vehicle - Google Patents

Abstract

PURPOSE:To lock a front wheel at engine stop, in a parking brake device for a traveling vehicle such as a tractor, by providing a spring for energizing a piston in the clutch operating direction in the oil chamber of a hydraulic clutch, providing a return oil chamber for pushing the piston in the clutch cutting direction, and also providing a switching valve for oil pressure supply to the both oil chambers. CONSTITUTION:A front wheel transmission system branched from a rear wheel transmission system to transmit a power to a front wheel through a hydraulic clutch 3 is formed. A piston 49 to be pushed in the clutch operating direction by oil pressure is provided in the oil chamber 48 of the hydraulic clutch 3, and a pressing spring 55 is provided between the piston 49 and a clutch body 40 to energize the piston 49 in the clutch operating direction. A return oil chamber 57 for pushing the piston 49 in the clutch cutting direction against the spring 55 is also provided. Further, a switching valve 58 is provided so that the oil pressure is supplied to the oil chamber 48 at OFF time and to the oil chamber 57 at ON time.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art For example, in the case of a tractor having a hydraulic clutch in a rear wheel transmission system, when the engine is stopped, the hydraulic clutch is disengaged, and the rear wheel cannot be braked by the engine. A rear wheel parking brake mechanism is provided on a rotating shaft that is always linked to the rear wheel, and the rear wheel parking brake mechanism is operated by a parking brake operating means.

[0003]

In the above-mentioned prior art, in the case where the front wheel transmission system has a hydraulic clutch, when this hydraulic clutch is in the disengaged state, the rear wheels can be rotationally locked but the front wheels cannot be rotationally locked. It is difficult, and when a heavy work implement is installed in the front like a tractor equipped with a front loader, the load applied to the rear wheels is reduced, and it may shift when parked on a slope. .

By the way, the hydraulic clutch of the front wheel transmission system is
As shown in FIG. 3, the first and second hydraulic packs 3A, 3B are located on both sides of the clutch body 40 in the axial direction, and each hydraulic pack 3A, 3B supplies a pressure oil to the oil chamber 48 to move the piston 49. By pushing against the return spring 50, the friction plate 51 and the clutch plate 52 are pressed to enter the clutch state, and the pressure oil supply to the oil chamber 48 is stopped, the return spring 50 returns the piston 49. The clutch is disengaged.

An electromagnetic switching valve 53 for supplying pressure oil to each oil chamber 48 is connected to the first and second hydraulic packs 3A and 3B, and when one of the electromagnetic switching valves 53 is turned on, the second hydraulic pack 3B enters the state. Thus, the rotation of the first transmission shaft 38 is directly transmitted to the second transmission shaft 39, at which time the other electromagnetic switching valve 53 is turned off and the other electromagnetic switching valve 53 is turned off.
When the first hydraulic pack 3A is turned on, the rotation of the first transmission shaft 38 is transmitted to the second transmission shaft 39 via the gears 41 and 43, the rotation shaft 7 and the gears 44 and 42, and both electromagnetic switching is performed. When the valve 53 is turned off, the power transmission from the first transmission shaft 38 to the second transmission shaft 39 is cut off. That is, when the engine is stopped and both electromagnetic switching valves 53 are turned off, the front wheels are in an idle state, and even if the rear wheels are rotationally locked, the front wheels cannot be rotationally locked.

According to the present invention, a hydraulic clutch that transmits power to the front wheels in a disconnectable / connectable manner is set to a clutch disengaged state when the hydraulic pressure is supplied, and a clutch engaged state when the hydraulic pressure is stopped by a spring force so that the engine is stopped. An object of the present invention is to provide a parking brake device for a traveling vehicle in which front wheels can be rotationally locked.

[0007]

A concrete means for solving the problem in the present invention is to branch from a rear wheel transmission system having a hydraulic clutch 2 and connect / disconnect power to a front wheel via a multi-plate hydraulic clutch 3. In a parking brake device for a traveling vehicle, in which a rear wheel parking brake mechanism 5 is provided on a rotating shaft 4 that forms a front wheel transmission system that freely transmits and is always interlocked with a rear wheel, the hydraulic clutch 3 is an oil chamber 48. A pressure spring 55 for urging the piston 49 in the clutch engagement direction is provided between the piston 49 and the clutch body 40, which are pushed in the clutch engagement direction by supplying pressure oil to the clutch. A return oil chamber 57 that pushes in the clutch disengagement direction is formed, and pressure oil is supplied to the oil chamber 48 by turning it off and pressure oil is supplied to the return oil chamber 57 by turning it on. It is that are provided switching valve 58 supplies.

[0008]

When the traveling vehicle is stopped and the parking brake operating means is operated, the rear wheel parking brake mechanism 5 is operated to lock the rotary shaft 4 so as not to rotate and the electromagnetic switching valve 58 is turned off by stopping the engine E. Then, the pressure oil supply to the hydraulic clutch 3 is stopped.

When the pressure oil is stopped from being supplied to the first hydraulic pack 3A of the hydraulic clutch 3, the piston 49 is pushed from the clutch disengaged state to the clutch engaged state by the urging force of the push spring 55, so that the clutch engaged state. As a result, the second transmission shaft 39, which is always in an interlocking relationship with the front wheels, is brought into an interlocking state with the first transmission shaft 38 directly connected to the rotary shaft 4. As a result, since the rotary shaft 4 is rotationally locked by the rear wheel parking brake mechanism 5, the front wheels are also locked.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 to 3, reference numeral 11 denotes a transmission case constituting a vehicle body of a traveling vehicle such as a tractor, in which a traveling system and a PTO system transmission are arranged, and a front portion of the transmission case via a clutch housing portion 12. Is connected to the engine E. 13 is a flywheel,
It is directly connected to the PTO propulsion shaft 14, and is connected to the traveling propulsion shaft 15 via the main clutch 16 so that power can be connected and disconnected.

The traveling power transmission system includes a hydraulic switching type high / low speed change mechanism 18 having a hydraulic clutch 17 from a traveling propulsion shaft 15, a 5-step manual switching type main speed change mechanism 19, and a hydraulic switching type forward / backward movement having a hydraulic clutch 2. It has a switching mechanism 20, a manual switching-type auxiliary transmission mechanism 21, etc., and is capable of transmitting power from the bevel pinion shaft 22 to the left and right rear wheels via the rear wheel differential mechanism 23. I can say.

A transmission gear 2 is attached to the bevel pinion shaft 22.
5 is provided and always meshes with the gear 26 of the rotary shaft 4. The rotary shaft 4 is capable of transmitting power to a hydraulic switching type front wheel drive / double speed switching mechanism 27 having a hydraulic clutch 3. Power is transmitted from the drive / double speed switching mechanism 27 to the front wheels via the transmission shaft 28. These are front wheel transmission systems, and the power branched from the rear wheel transmission system is transmitted via the gears 25 and 26.

No transmission mechanism having a hydraulic clutch is provided between the bevel pinion shaft 22 and the rear wheels. Therefore, the hydraulic clutch 2 (or the hydraulic clutch 17 may be used) is disengaged. Even if the interlocking relationship between the engine 22 and the engine E is cut off, the rotary shaft 4 is in an interlocking relationship such that it can always rotate integrally with the rear wheels, and the rear wheel parking brake mechanism 5 is provided on the rotary shaft 4. Has been.

In the rear wheel parking brake mechanism 5, a plurality of friction plates 30 are spline-fitted to the rotary shaft 4, and the friction plates 30 can be sandwiched between a brake pad 32 and a brake plate 33 provided on a brake case 31. The cam 34 presses these to lock the rotation of the rotary shaft 4. The brake case 31 having the brake pad 32 and the brake plate 33 is a unit, and can be inserted into the inside of the transmission case 11 from the side surface thereof.
It also supports a cam shaft 35 that rotates. This camshaft 35
A lever 36 is fixed to and is rotated by a Bowden wire and parking brake operating means (not shown).
A return force is applied to the lever 36 by a spring.

The front wheel drive / double speed switching mechanism 27 is provided between a first transmission shaft 38 directly connected to the rotary shaft 4 and a second transmission shaft 39 directly connected to the transmission shaft 28, and in parallel with these shafts. A rotary shaft 7 is arranged as a counter shaft. The clutch body 40 of the hydraulic clutch 3 is fixed to the first transmission shaft 38, the first gear 41 is loosely fitted to the first transmission shaft 38, and the second gear 42 is fixed to the second transmission shaft 39. The pack selectively fixes the first gear 41 and the second gear 42 to the clutch body 40.
Third and fourth gears 43 and 44 are fixed to the rotary shaft 7, the third gear 43 meshes with the first gear 41, and the fourth gear 4
4 is always meshed with the second gear 42.

That is, the hydraulic clutch 3 is of the multi-plate type as in the prior art, the first hydraulic pack 3A is for the front wheel double speed, and when engaged, the first gear 41 is fixed to the clutch body 40, The power of the first transmission shaft 38 is increased in two stages via the rotary shaft 7 and transmitted to the second transmission shaft 39, so that the front wheels are driven at a peripheral speed about twice that of the rear wheels. The second hydraulic pack 3B is for front wheels at constant speed, and when in the engaged state, the second gear 39 is fixed to the clutch body 40, the power of the first transmission shaft 38 is directly transmitted to the second transmission shaft 39, and the front wheels are Drives at approximately the same circumferential speed as the rear wheels.

There is no speed change mechanism having a hydraulic clutch between the second transmission shaft 39 and the front wheels, so that either the first hydraulic pack 3A or the second hydraulic pack 3B of the hydraulic clutch 3 is engaged. Then, since the second and fourth gears are always meshed with each other, the first transmission shaft 38 is in an interlocking relationship such that it can always rotate integrally with the front wheel.
When the rotary shaft 4 directly connected to 8 is locked by the rear wheel parking brake mechanism 5, the front wheels are also locked.

The first and second hydraulic packs 3A and 3B are located on both sides of the clutch body 40 in the axial direction, and the second hydraulic pack 3B has the same structure as that of the conventional technique shown in FIG. By supplying the pressure oil, the piston 49 is pushed against the return spring 50, the friction plate 51 and the clutch plate 52 are pressed to enter the clutch state, and the supply of the pressure oil to the oil chamber 48 is stopped to return the piston 49. The spring 50 returns the piston 49 to the clutch disengaged state,
The electromagnetic switching valve 53 is also turned on to supply the pressure oil from the pump P to the second hydraulic pack 3B, and turned off to drain the oil.

On the other hand, as shown in FIG. 1, the first hydraulic pack 3A pushes the piston 49 by supplying the pressure oil to the oil chamber 48 to push the friction plate 51 and the clutch plate 52. Although the configuration for putting the clutch in the engaged state is similar, a push spring 55 is provided between the piston 49 and the clutch body 40, and the piston 49 has a return piston 5
6 is connected, and a return oil chamber 57 is formed between the return piston 56 and the clutch body 40.

The electromagnetic switching valve 58 can selectively supply the pressure oil from the pump P to the oil chamber 48 and the return oil chamber 57, and when turned on, the pressure oil is supplied to the return oil chamber 57. Then, the piston 49 and the return piston 56 are pushed against the push spring 55, the friction plate 51B and the clutch plate 52B are disengaged, the clutch is disengaged, and the pressure oil is discharged to the oil chamber 48. Supply and put in the clutch. Then, when the electromagnetic switching valve 58 is turned off and the pump P is stopped, only the push spring 55 pushes the piston 49, and the first hydraulic pack 3A is put in the clutched state even if the pressure oil is not supplied. Become.

The electromagnetic switching valve 58, together with the electromagnetic switching valve 53, is adapted to be operated by operating means for the front wheel drive / double speed switching mechanism 27. When the electromagnetic switching valve 53 is turned on to bring the second hydraulic pack 3B into the clutch-engaged state (constant speed of front wheels), the electromagnetic switching valve 58 is turned off, but the first hydraulic pack 3A has pressure oil for clutch disengagement. Is supplied.

When the engine E is turned off, both hydraulic packs 3A, 3
When the supply of the pressure oil of B is stopped, only the first hydraulic pack 3A is put into the clutch by the push spring 55, and the rear wheel parking brake mechanism 5 is operated by operating one parking brake operating means. At the same time, the front wheel transmission system will also be rotationally locked. The present invention is not limited to the above embodiment, but can be variously modified. For example, the first hydraulic pack 3A of the hydraulic clutch 3 may be arranged on the front wheel constant speed side, and the first and second hydraulic packs 3 may be arranged.
A and 3B may be switchable by a single switching valve, the piston 49 and the return piston 56 may be integrated, and the hydraulic clutch 3 is configured to only connect and disconnect the shafts 38 and 39. Then, the present invention may be applied thereto, and the switching valves 53 and 58 may be of a manual type.

[0023]

According to the present invention detailed above, the hydraulic clutch 3 is pushed in the clutch engagement direction by supplying the pressure oil to the oil chamber 48, and the clutch body 4 is pushed.
A push spring 55 for urging the piston 49 in the clutch engagement direction is provided between it and 0, and a return oil chamber 57 for pushing the piston 49 in the clutch disengagement direction against the push spring 55 is formed and turned off. Since the switching valve 58 that supplies the pressure oil to the oil chamber 48 and turns it on to supply the pressure oil to the return oil chamber 57 is provided, the engine E is stopped and the rear wheel parking brake mechanism 5 is operated. By doing so, not only the rear wheels but also the front wheels can be rotationally locked, and the simultaneous locking of the front and rear wheels makes it possible to lock more than the rear wheels even when parked on a slope with a heavy work implement mounted on the front. It will be possible to park securely.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a main part showing an embodiment of the present invention.

FIG. 2 is an overall schematic diagram of a tractor mission.

FIG. 3 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 2 hydraulic clutch 3 hydraulic clutch 4 rotary shaft 5 rear wheel parking brake mechanism 22 bevel pinion shaft 27 front wheel drive / double speed switching mechanism 38 first transmission shaft 39 second transmission shaft 40 clutch body 48 oil chamber 49 piston 55 push spring 56 return piston 58 Electromagnetic switching valve

Claims (1)

[Claims] 1. A front wheel transmission system that branches from a rear wheel transmission system having a hydraulic clutch (2) and transmits power to the front wheel via a multi-plate hydraulic clutch (3) in a freely connectable / disconnectable manner. In a parking brake device for a traveling vehicle in which a rear-wheel parking brake mechanism (5) is provided on a rotating shaft (4) that is always interlocked with the hydraulic brake (3), the hydraulic clutch (3) supplies pressure oil to an oil chamber (48). A push spring (55) for urging the piston (49) in the clutch engagement direction is provided between the piston (49) that is pushed in the clutch engagement direction by the operation and the clutch body (40), and the piston (49) is provided. Of the oil chamber (4) by forming a return oil chamber (57) that pushes in the clutch disengagement direction against the push spring (55) and is turned off.
8) A parking brake device for a traveling vehicle, characterized in that a switching valve (58) for supplying pressure oil to the return oil chamber (57) by supplying pressure oil to the return oil chamber (57) is provided.