JPS5934083B2 - Work equipment operating device for towing vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for a towing vehicle such as a tractor or combine harvester having a hydraulic working machine lifting device.

Generally, a main spool is provided midway through the high-pressure piping of the hydraulic circuit, which switches the high-pressure oil generated by the hydraulic pump to be sent to the hydraulic cylinder or returned to the tank.

Since the main spool is operated by a manual lever, the gap between the control valve and the main spool is made large so that it can be operated easily, but the pressurized oil in the hydraulic cylinder pressed by the weight of the work equipment flows from this gap into the tank. There was a problem in which the suspended work equipment would naturally fall when the hydraulic pump stopped.

For this reason, in recent years, lock valves and raised position holding valves have been installed to prevent the hanging work equipment from descending, but the lock valves require the hydraulic circuit to be locked every time the hydraulic pump is stopped. In many cases, people do not operate the machine because it is cumbersome and difficult to operate, and when working below the machine, the worker gets stuck under the machine if it falls, or in circuits with holding valves, the machine must be lowered with the hydraulic pump stopped. Even if you try to lower the operating lever to lower the operating lever, the work equipment will remain in that position and will not lower, and the next time you operate the hydraulic pump, if the operating lever is in the lower position, the operating equipment will move. It was extremely dangerous to fall.

In order to eliminate such problems, the present invention has taken the following technical measures.

That is, a main spool 3 for lifting/lowering control having "upper", "lower", and "middle" positions is provided between the hydraulic cylinder 1 for lifting and lowering the working machine and the hydraulic pump 2, and 1, there is provided a reverse valve 4 for controlling return oil from the hydraulic cylinder 1, and when the oil in the back pressure chamber 20 is discharged, a reverse valve 4 is provided from the exit direction of the reverse valve 4. The check valve 4 is configured to allow backflow at a pressure of Sometimes, the oil in the back pressure chamber 20 of the check valve 4 flows into the tank 2.
2, and the pressure oil in the hydraulic cylinder 1 is drained to the tank 2.
A preceding valve 5 is provided which operates to switch so as to discharge the liquid to
Furthermore, this advance valve 5 allows the operating lever for operating the main spool 3 to be kept in the "down" position even when the hydraulic pump 2 is not operating.
When operated to the position, the sub spool 2 interlocks with the preceding valve 5.
8 is pushed in so that the oil in the back pressure chamber 20 of the check valve 4 is discharged to the tank 22.

The present invention has the following technical effects due to the above configuration.

That is, when the engine is stopped and the rotation of the hydraulic pump 2 is stopped, the advance valve 5 sets the check valve 4 in the hydraulic circuit to the backflow prevention state, and restricts the return of pressure oil in the hydraulic cylinder 1 to the working machine 8. However, when the operating lever 7 is operated to move the main spool in the lowering direction of the work equipment 8, the preceding valve 5 is switched to the operating state (the check valve 4 is switched to the operating state to allow backflow). ) to enable the work implement 8 to be lowered, and when the hydraulic pump 2 is in operation, the high pressure oil of the hydraulic pump 2 is used to activate the advance valve 5 to lower the work implement 8.

Next, to explain an example of a diagram, 9 is a piston moving within the hydraulic cylinder 1, 10 is a connecting rod, 11 is a lift arm, 12 is a check valve of the type, 13 is a variable throttle valve, and 14 is an IJ IJ- 15 and 15' are pipes that connect the check valve 4 and the hydraulic cylinder 1, 16 is a pipe that connects the main spool 3 and the check valve 4, 1T is the valve body, 18 is the push spring, and 19 is the valve chamber. , 20 is a back pressure chamber, 21 is a pressure oil escape passage to the tank 22, 23 is a push spring that presses the advance valve 5 into a non-operating state, 24 is a control valve, and in the embodiment, a check is provided in the control valve 24. A valve 4 and a preceding valve 5 are provided, but these are separate control valves 24.
You can take it outside.

Reference numeral 25 denotes a spool arm that controls the main spool 3, and a support shaft 26 is provided on the machine frame so that it can swing around the support shaft 26. One end of the swinging arm contacts the end surface of the main spool 3, and the other side is operated. An actuator 2γ that operates in conjunction with the lever l is in contact with the spool arm 25, and the end face of the main spool 3 and the actuator 2γ sandwich and press the spool arm 25 to restrict its swinging.

In Fig. 2, 28 is a sub-spool connected to the preceding valve 5, 29 is a sub-spool arm, and a support shaft 30 is provided on the machine frame.
It is attached so that it can swing freely.

31 is a suppressing portion provided on the spool arm 25.

In FIG. 1, the main spool 3 is in the neutral position 3a, but by operating the operating lever γ, the high pressure pipe 32 from the hydraulic pump 2 and the pipe 16 to the check valve 4 can be connected.
Neutral position 3a, lowered position 3b, raised position 3c
You can switch the operation with either ().

33 and 34 are both return circuits to the tank 22, 35 is a relief valve, 36 is a compensator, 3γ is piping to the back pressure chamber of the compensator 36, 38 is a flow divider valve, 39
is the oil suction pipe.

In Fig. 3, 7/ is a draft lever, and r'' is a position lever, both of which have a double shaft configuration and are swingably attached to the machine frame. It is fixed by the brake body 40, 40 and does not swing naturally.

Manual operation of the trafton bar γ′ is transmitted to the shaft 41, bell crank 42, shaft 43, draft arm 44, actuator 2γ, and spool arm 25, and the traction resistance of the work equipment 8, etc. acts as a pressing force on the arm rod 45. It is transmitted to the draft arm 44, the actuator 2γ, and the spool arm 25 via a control 46 that connects the arm rod 45 and the draft arm 44.

The pin 4γ is a safety device that engages when the piston 9 is pushed backwards beyond a certain level.

Similarly, manual operation of the position lever γ" is transmitted to the shaft 48, bell crank 49, shaft 50, position arm 51, actuator 21, and spool arm 25, and the vertical position of the work equipment etc. is detected by the rotation of the lift arm 11. The rotation of the cam 53 provided around the moving shaft 52 transmits the rotation to the position arm 51, the actuator 2γ, and the spool arm 25 via the rod arm 54, which is swingably attached to the machine frame, and the pressing portion 55.

Next, the operation will be explained. When the hydraulic pump 2 is operated by the power of an engine or the like, oil is sucked from the suction pipe 39, becomes high pressure, flows into the pipe 32, and is sent to the control valve 24.

Now, when the main spool 3 is in the neutral position 3a as shown in Fig. 1, the pressure oil passes through the compensator 36 and enters the tank 22.
When the main spool 3 returns to the raised position 3c, the high pressure oil in the pipe 32 is transferred to the pipe 16 and the pipe 3γ.
The compensator 36 becomes a closed circuit due to the oil flowing into the piping 3γ to the back pressure chamber of the compensator 36.
The high pressure oil flows only into the pipe 16, opens the valve body 1γ of the check valve 4 against the push spring 18, and flows into the pipe 15.

The high pressure oil flowing into the pipe 15 expands the check valve 12 and flows into the hydraulic cylinder 1, moves the piston 9, raises the lift arm 11 via the connecting rod 10, and also raises the work implement 8.

When the piston 9 moves to the vicinity of the end, the piston 9 engages with the pin 4γ and moves the pin 4γ in the direction of arrow H in FIG.

Therefore, the draft arm 44 integrated with the pin 4γ also moves in the direction of the arrow H, and the actuator 2γ and the spool arm 25 similarly move in the direction of the arrow H.

When the spool arm 25 moves in the direction of the arrow H, the main spool 3 also protrudes by the push spring 5γ and becomes stable when it reaches the neutral position 3a.

Next, when both the draft lever γ′ and the position lever γ are moved in the downward direction (in the direction of the arrow in FIG. 2), the bell cranks 42 and 49 also move in the direction of the arrow around the shafts 41 and 48, and the draft arm Since the middle part of the actuator 2γ is supported by the rod 46, the actuator 2γ moves in the direction of the arrow H, and the position arm 51 has the middle part supported by the suppressing part 55 of the rod arm 54, and pulls the lower end in the direction of the arrow H. spring 5
8, the spool arm 25 is pressed by the pressing spring 5γ of the main spool 3, and the main spool 3 is simultaneously extended to the lowered position 3b.

When the main spool 3 reaches the lowered position 3b, the piston 9 is pushed back by the weight of the working machine 8, and the pressure oil passes through the throttle valve 13 and reaches the check valve 4.

On the other hand, high-pressure oil from the hydraulic pump 2 flows from the pipe 32 to the pipe 6 and switches the preceding valve 5 from the state 5b to the valve chamber 5a, which causes the back pressure of the back pressure chamber 20 of the check valve 4 to change. The pressure escapes from the pipe 6' to the tank 22 through 21, so the valve body 1
r is pushed in the direction of arrow A, the pressure oil in the hydraulic cylinder 1 returns to the tank 22 through the pipes 16 to 34, and the work implement 8 descends.

At this time, the piping 3 communicating with the back pressure chamber of the compensator 36
Since the oil of γ escapes to the tank 22 through the pipe 33, the high-pressure oil that pushed the preceding valve 5 immediately returns to the tank 22 through the compensator 36, and the high-pressure oil is balanced between both valves.

Next, when the engine etc. is stopped and the hydraulic pump 2 is not operating, when an attempt is made to lower the working equipment 8 which has been raised, in the conventional type, the advance valve 5 is pressed by the push spring because high pressure oil does not flow into the piping 32. 23, and there is no difference between the internal pressure of the back pressure chamber 20 of the check valve 4 and the internal pressure of the valve chamber 19, so the pressing spring '
At step 18, the valve body 1γ is pressed against the wall and the work implement 8 does not descend.

This configuration has the advantage that the gap between the main spool 3 and the insertion hole provided in the control valve 24 is large, making it easier to operate the manual operation lever γ, but every time the work equipment 8 is lowered, the engine It was a hassle to have to start it.

However, in this invention, when lowering the work equipment, the advance valve 5 is automatically switched by pressure oil while the engine is running, and when the engine is stopped, the control lever is moved to switch the sub-valve in conjunction with the advance valve 5. By pushing in the spool 28, the oil in the back pressure chamber 20 of the check valve 4 is transferred to the tank 2.
2. As a result, the work equipment can be easily lowered regardless of whether the engine is running or not.

In this embodiment, this preceding valve 5 is linked with the lowering operation of the operating lever γ' and the check valve 4 is operated to restore backflow, so the two operating levers γ' and γ' are moved at the same time. It is possible to lower the working machine 8 without starting the engine using only one lever, and it also serves as a safety device to prevent the working machine from falling even if someone other than the operator tampers with only one lever.

In the embodiment shown in FIG. 2, the sub spool 28 connected to the preceding valve 5 is suppressed by the sub spool arm 29, but as shown in FIGS. 31" like sub spool 28
The actuators 2γ and 2 are provided on the draft arm 44 and the position arm 51, with the pressing portions 31' and 31'' facing each other.
By moving γ in the direction of arrow H and pushing the spool arm 25 with the push spring 5γ of the main spool 3, the sub spool 28 is directly pressed by the suppressing parts 31' and 31'' provided on the spool arm 25. A compact link device can be provided by eliminating the sub-spool arm 29.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is a diagram of hydraulic piping, Fig. 2 is a partially sectional side view of the main part, Fig. 3 is a partially sectional front view thereof, and Figs. The figure is a side view of another embodiment. In the figure, symbol 1 is a hydraulic cylinder, 2 is a hydraulic pump, 3 is a main spool, 4 is a check valve, 5 is a leading valve, 6 is a different hydraulic circuit, and γ is an operating lever.

Claims (1)

[Claims] 1 A main spool 3 for lifting and lowering control having "upper", "lower" and "middle" positions is provided between the hydraulic cylinder 1 for lifting and lowering the working machine and the hydraulic pump 2, and the main spool 3 and the hydraulic cylinder 1 A check valve 4 for controlling the return oil from the hydraulic cylinder 1 is provided between the hydraulic cylinder 1 and the check valve 4. When the oil in the back pressure chamber 20 is discharged, the check valve 4 controls the return oil from the exit direction of the check valve 4. The check valve 4 is configured to allow backflow under pressure, and is provided between the check valve 4 and the main spool 3 for lifting/lowering control when the hydraulic pump 2 is in operation and the main spool 3 is in the "lower" position. Then, the oil in the back pressure chamber 20 of the check valve 4 is transferred to the tank 22.
A preceding valve 5 is provided which operates to switch so that the oil is drained to the hydraulic cylinder 1 and discharged to the pressure oil tank 22 in the hydraulic cylinder 1. Furthermore, this preceding valve 5 operates the main spool 3 even when the hydraulic pump 2 is not operating. When the operating lever is moved to the "down" position, the sub-spool 28 that is linked to the preceding valve 5 is pushed in, and the oil in the back pressure chamber 20 of the check valve 4 is drained into the tank 2.
1. A work machine operating device for a towing vehicle, characterized in that the work machine operating device is configured to be interlocked so that the work machine is ejected from the vehicle.