JPH0414533A - Oil-pressure circuit for tractor - Google Patents

Abstract

PURPOSE:To speed up the action of an operating machine by a method in which a lubricating circuit to an oil-pressure clutch is dividedly connected to the main oil-pressure circuit through a check valve and lubricating oil is interrupted and jointly directed to the main oil-pressure circuit by means of a solenoid valve provided. CONSTITUTION:A lubricating circuit 34 is connected through a branched circuit 36 with a check valve 35 to the main oil-pressure circuit. The check valve 35 has a function of allowing the inflow of oil from the circuit 34 into the main oil-pressure circuit but of interrupting the inflow of oil in case of backward flow. A solenoid valve 37 provided for the circuit 34 serves to interrupt the inflow of lubricating oil into oil-pressure clutches 20 and 21 during switching period and to allow the coil to go into the main oil-pressure circuit. The amount of oil in the main oil-pressure circuit can thus be increased by using the lubricating oil when not in use and the action of the operating machine can be speeded up.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic circuit for a tractor.

(Prior art) Tractors that use a wet hydraulic tarante for the forward/reverse switching device of the traveling system are equipped with a lubrication circuit that supplies lubricating oil to the disc portion of the hydraulic clutch, in addition to the working hydraulic circuit.
This lubrication circuit supplies lubricating oil to the disc portion of the hydraulic clutch to keep it lubricated at all times.

(tlH to be Solved by the Invention> Lubrication of the hydraulic clutch is necessary during its disconnection/connection operations, but is unnecessary once the hydraulic clutch is in a completely disconnected state.

On the other hand, when working with a front loader attached to a tractor, the hydraulic clutch for forward/reverse switching is frequently engaged/disconnected. In this case, when raising the boom after scooping earth and sand into the packet, the hydraulic clutch for forward/reverse switching is disconnected, and the boom is raised while temporarily stopping traveling. Loader work can be performed efficiently by increasing the speed at which the boom rises.

However, since the amount of oil in the main hydraulic circuit is determined by the discharge amount of the hydraulic pump, it is not possible to increase the amount of oil only at this time to increase the rising speed of the boom.

In view of this point, the present invention attempts to increase the amount of oil by making the lubricating oil in the lubrication circuit merge with the oil in the main hydraulic circuit.

(Means for Solving the Problems) The present invention provides a hydraulic clutch 2 for switching forward and backward movement of the traveling system 15.
In the hydraulic circuit of a tractor, which is equipped with a lubricating port a34 for lubricating 0.21 and a main hydraulic circuit 24 for work, the lubricating circuit 34 is connected to the main hydraulic pressure via a check valve 35 that shuts off oil from the main hydraulic circuit 24. In addition to branching connection to the circuit 24, when the hydraulic clutches 20 and 21 are in the switching state, the hydraulic clutch 2
The lubricating circuit 34 is provided with a valve 37 for shutting off lubricating oil to the main hydraulic circuit 24 and allowing the oil to flow into the main hydraulic circuit 24.

(Function) When the hydraulic clutch 20.21 is in a state other than the disconnected state, lubricating oil is supplied from the lubrication circuit 34 to the hydraulic clutch 20.21 for lubrication.

When the hydraulic clutch 20.21 is disengaged, the valve 37 operates,
Since the supply of lubricating oil to the hydraulic clutches 20, 21 is cut off, the oil in the lubricating circuit 34 flows into the main hydraulic circuit 24 via the check valve 35. Therefore, the amount of oil in the main hydraulic circuit 24 increases, and when the boom 9 is raised during loader work by the front loader 8, for example, the raising speed can be made sufficiently fast.

Furthermore, at this time, the hydraulic clutches 20 and 21 are completely disconnected and no lubrication is required, so there is no problem in how many ships the lubricating oil supply is cut off.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 2, l denotes a tractor, which includes an engine 2, a transmission case 3, a bonnet 4, an instrument panel 5, a handle 6, front wheels 7, and the like. 8 is a front loader, which is composed of a boom 9, a packet 10, a boom cylinder 1), a packet cylinder 12, and the like. This front loader 8
is detachably attached to the front part of the tractor 1 via a mast 13.

As shown in FIG. 3, the engine 2 drives a traveling system 15 via a main clutch 14.

The running system 15 includes a forward/reverse switching device 16, a transmission 17, a rear wheel differential device 1B, etc.
The forward/reverse switching device 16 to which 9 is connected has a forward hydraulic clutch 2o and a reverse hydraulic clutch 21 of a wet disc clutch type.

FIG. 1 shows a hydraulic circuit of the tractor 1. In FIG. 1, 22 is a main hydraulic pump for working, and 23 is a sub-hydraulic pump, which are driven by the engine 2. 24 is a main hydraulic circuit for working, which supplies oil to the three-point linkage mechanism hydraulic system (not shown), the boom cylinder 1 of the front loader 8, the packet cylinder 12, etc. through a valve device 25. ing. 26 is a forward/reverse switching valve, which is a forward/reverse switching lever 2 attached to the instrument panel 5, as shown in FIG.
70 In conjunction with front and rear operation, forward/reverse hydraulic clutch 20
．． It is designed to control 21. In addition, as shown in FIG. 4, the switching lever 27 has a neutral position N and a forward position F1.
They are configured to be able to be positioned respectively at the backward movement position R.

28 is an inching valve, which is operated by a pedal 29. Reference numerals 30 to 32 are relief valves, and 33 is a pressure sensing section for controlling the pressure increase characteristic of the relief valve 31.

34 is a lubrication circuit that connects the auxiliary hydraulic pump 23 to the relief valve 3.
The oil lubrication sent through 1 is applied to the hydraulic clutch 20゜2.
1 is supplied to each disk section.

This lubrication circuit 34 is a branch circuit 3 having a check valve 35.
6 to the main hydraulic circuit 24. The check valve 35 allows oil to flow from the lubrication circuit 34 to the main hydraulic circuit 24 and blocks the flow of oil from the main hydraulic circuit 24 to the lubrication circuit 34. Reference numeral 37 denotes a normally open electromagnetic on-off valve, which is interposed in the lubricating circuit 34' on the downstream side of the branch circuit 36. A solenoid portion 38 of this on-off valve 37 is connected to a switch 39 via a drive circuit, and is energized and closed when the switch 39 detects that the switching lever 27 is in the neutral position.

During loading work by the front loader 8, the switching lever 27 is operated back and forth, the forward/reverse hydraulic clutches 20, 21 are switched via the switching valve 26, and the tractor 1 is frequently moved forward and backward.

When the switching lever 27 is in the forward position F or the reverse position R, the switch 39 is off, so the solenoid section 38 of the on-off valve 37 remains demagnetized. Therefore, the on-off valve 37 is open, and the lubricating circuit 34 is connected to each hydraulic clutch 2.
Supply lubricating oil to the 0.21 disk portion to lubricate them.

When the switching lever 27 is operated to the neutral position N, the switching valve 26
becomes neutral, and the forward and reverse hydraulic clutches 20 and 21 are both disengaged, so power transmission from the traveling system 15 is cut off and the tractor 1 stops traveling. Meanwhile, switch 39 is turned on,
Since the solenoid section 38 of the on-off valve 37 is energized, the on-off valve 37 closes and cuts off the supply of lubricating oil. Therefore, the oil in the lubrication circuit 34 flows through the branch circuit 36 and the check valve 35 into the main hydraulic circuit 24, and the amount of oil in the main hydraulic circuit 24 increases. Therefore, if the changeover lever 27 is returned to neutral to stop traveling after pushing the Haken 10 into the earth and sand and scooping up the earth and sand, the amount of oil in the main hydraulic circuit 24 will increase by the flow rate of the lubricating oil, so the oil flow will continue. and operate the valve device 25 to open the boom cylinder 1).
When oil is supplied to the bottom side of the boom cylinder 1), the boom cylinder 1) is rapidly extended and the boom 9 is raised at a high speed.

At this time, since the hydraulic clutches 20 and 21 do not require lubrication, there are no problems such as seizure.

When the switching lever 27 is operated to the forward position 1F or the reverse position R, the on-off valve 37 opens and supplies lubricating oil to the hydraulic clutches 20, 21. Therefore, the oil amount in the main hydraulic circuit 24 returns to the discharge amount of the main hydraulic pump 22. Note that since the branch circuit 36 includes the check valve 35, oil will not flow back from the main hydraulic circuit 24 to the lubrication circuit 34 at this time.

In addition, although the on-off valve 37 is used in the embodiment, a switching valve may be interposed in the branch portion of the lubrication circuit 34.

Further, the working machine may be other than the front loader 8.

(Effects of the Invention) According to the present invention, lubrication is achieved through the check valve 35 that shuts off oil from the main hydraulic circuit 24! 34 to the main hydraulic circuit 24, and a valve 37 for cutting off lubricating oil to the hydraulic clutch 20.21 and allowing oil to join the main hydraulic circuit 24 when the hydraulic clutch 20.21 is in the switching state. 34, the amount of oil in the main oil pressure diagram M24 can be increased using lubricating oil when it is not needed. Therefore, the working machine can be operated quickly, and especially when used for loader work by the front loader 8, work efficiency is significantly improved.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of the tractor, Fig. 3 is a block diagram of the traveling system, and Fig. 4 is an explanation of the forward/reverse switching lever section. It is a diagram. 1...Tractor, 8...Front loader, 15...
- Traveling system, 16... Forward/forward switching device, 20... Forward hydraulic clutch, 21... Reverse hydraulic clutch, 24...
- Main hydraulic circuit, 34... Lubricating circuit, 35... Check valve, 37... Solenoid on-off valve.

Claims (1)

[Claims] (1) Hydraulic clutch for switching forward/backward in the travel system (15) (
20) In a tractor hydraulic circuit that includes a lubrication circuit (34) that lubricates (21) and a main hydraulic circuit (24) for work, a check valve (35) that shuts off oil from the main hydraulic circuit (24) is provided. ) to the main hydraulic circuit (
24), and a hydraulic clutch (20) (
21) is in the switching state, the hydraulic clutches (20) and (21)
A hydraulic circuit for a tractor, characterized in that a lubricating circuit (34) is provided with a valve (37) for cutting off lubricating oil to the main hydraulic circuit and allowing the oil to join the main hydraulic circuit (24).