JPS629775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic pressure control device for controlling the operation of a PTO clutch provided in a mobile agricultural machine such as a tractor for extracting operating power.

When driving the working part of a working machine connected to a mobile agricultural machine, if the working machine is rotary,
It is desirable to supply pressure oil to the clutch cylinder at one time to prevent the so-called half-clutch state when the PTO clutch is connected.
For example, in the case of a working machine such as a mower, which has a large inertia of the working part, it is desirable to gradually connect the PTO clutch so as to maintain the half-clutch state for a while. When connected to the power transmission system, a large impact force acts on the power transmission system due to the large inertia of the working part, causing problems such as the safety pin breaking.

A fluid pressure temporary increase device that temporarily increases the fluid pressure is known, but because it requires three valves, the relative operations of these valves become complicated and are likely to go awry. Since the fluid pressure to the supply side does not act as pilot pressure on the left and right chambers of the drain spool, the device can freely adjust the rising speed of this fluid pressure at each point in time when the fluid pressure increases temporarily. The problem is that it is not possible.

Therefore, in this invention, the number of valves is small and the pressure rise speed can be adjusted.The structure is such that the operating pressure oil supplied to the PTO clutch cylinder is transferred to the valve body of the pressure boost control valve. A valve chamber on the return side that pushes the valve body so that the return port communicates with the tank, and a valve chamber on the return prevention side that pushes the valve body so that the blocking part of the valve body blocks the return to the tank. The oil passage to the valve chamber on the return prevention side is also connected to the valve chamber of the one-time relief valve, so that as the hydraulic pressure of the pressure oil in the PTO clutch cylinder increases, it connects to the return port. The valve body is moved so that the blocking portions are alternately connected to the tank 2, and the capacity within the valve chamber of the one-hour relief valve is adjusted by an adjustment screw protruding from the outside of the one-hour relief valve. This is a hydraulic control device for the PTO clutch.

The specific structure will be explained based on one embodiment shown in the drawings. As shown in FIG. The pressure oil is supplied to the PTO clutch switching valve 4, and by switching the PTO clutch switching valve 4, the pressure oil is returned to the tank 2, or the pressure oil is supplied to the PTO clutch cylinder 5 via the throttle 6. There is.

Therefore, in this invention, as shown in FIG. It is equipped with a return port 10 that returns pressure oil from the oil passage 9 to the tank 2, and a closing part 11 that prevents the pressure oil from returning to the tank 2, and is provided with a return port 10 that returns pressure oil from the oil passage 9 to the tank 2, and a closing part 11 that prevents the pressure oil from returning to the tank 2. The pressure oil is supplied to each of the valve chambers 15 on the return prevention side through the valve chamber 13 and the throttle 14, and the valve body 12 is pushed toward the valve chamber 13 by the spring 16, so as to assist the action of the pressure oil. to strengthen

The pressure oil supplied to this other valve chamber 15 is also provided to be supplied to the one-hour relief valve 17,
The valve stem 20 of the one-hour relief valve 17 is pushed by pressure oil against a spring 19 until it comes into contact with the stopper 18.
Since the adjusting screw 22 is rotated by the rotating operation of the adjusting lever 21 and is pushed against the spring 19, its position can be changed and adjusted as desired.

And when connecting the PTO clutch
If the PTO clutch switching valve 4 is switched to the clutch connection position where pressure oil from the relief valve 3 is supplied to the boost control valve 7 as shown in FIG.
The pressure oil that has passed through is supplied to the return side valve chamber 13 of the boost control valve 7, and at the same time is also supplied to the return prevention side valve chamber 15 and the valve chamber 23 of the 1-hour relief valve 17 through the throttle 14, respectively. However, since it passes through the throttle 14, the amount of pressure oil flowing into the valve chambers 15 and 23 decreases, and the valve body 12 moves toward the valve chamber 15.
Therefore, the return port 10 is opened to the oil passage, and most of the pressure oil from the pump 1 is transferred to the tank 2.
PTO clutch cylinder 5.
A small amount of pressure oil will be supplied to the

After a while, the valve chamber 15 is filled with pressure oil and is energized by the spring 16, causing the valve body 12 to move into the valve chamber 1.
3, the return port 10 comes off from the oil passage 9 and the blocking part 11 cuts off the communication between the oil passage 9 and the valve chamber 13, and the pressure oil from the pump 1 does not return to the tank 2. is mainly supplied to the PTO clutch cylinder 5, and a portion passes through the throttle 14 and enters the valve chamber 1.
5 as well, the oil pressure inside the PTO clutch cylinder 5 will rise.

Then, this rising oil pressure and the same pressure oil act on the valve chamber 13 at the same time, so the throttle 14
The pressure in the valve chamber 13 becomes greater than the pressure in the valve chamber 15 that is throttled and supplied by the valve chamber 15, and therefore the valve body 12 is pushed toward the valve chamber 15 and is supplied to the return port 10.
opens into the oil passage 9, and the pressure in the valve chamber 13 begins to drop rapidly.

Then, the pressure in the valve chamber 15 and the spring 16 push the valve body 12 back toward the valve chamber 13, preventing the oil from returning to the tank 2 and increasing the pressure of the pressure oil in the PTO clutch cylinder 5. In this way, by gradually moving the valve body 12 left and right, a part of the pressure oil from the pump 1 is released into the tank 2, or is supplied into the PTO clutch cylinder 5, and the pressure oil is released into the PTO clutch cylinder 5. The pressure oil of No. 5 rises gradually as shown in the range R ₁ of the solid line pressure curve F ₁ in the pressure rise diagram of FIG. When this pressure rises, a part of the pressure oil supplied into the valve chamber 15 escapes to the valve chamber 23 of the one-hour relief valve 17, so the valve body 12
The force moving the valve towards the valve chamber 13 becomes weaker and the valve chamber 1
The time it takes for the pressure oil in PTO clutch cylinder 5 to return to tank 2 becomes longer, and as a result, the rate of increase in oil pressure in PTO clutch cylinder 5 becomes gradual as in the range _R1 described above. And the valve stem 2 of the 1 o'clock relief valve 17
0 comes into contact with the stopper 18, the hydraulic pressure in the PTO clutch cylinder 5 reaches the pressure _P1 shown in FIG.
2 toward the valve chamber 13 becomes greater, so that the rate of pressure increase in the PTO clutch cylinder 5 increases as shown in range R ₂ in FIG. When the pressure inside the PTO clutch cylinder 5 reaches a predetermined pressure _P2 set by the relief valve 3, the relief valve 3 returns the pressure oil from the pump 1 to the tank 2. A predetermined pressure is maintained, and in Fig. 5, the rising state of the rotational speed of the PTO shaft corresponding to the above-mentioned pressure rise process is shown by the rotational speed curve _S1 , and the range is as follows.
The configuration is such that the rise is gradual in R ₁ and somewhat steep in range R ₂ .

The pressure regulating valve box 24 which incorporates the above-mentioned pressure increase control valve 7 and the one-hour relief valve 17 as shown in FIG. Attach the joint as shown in Fig. 3 and install the 1 o'clock relief valve 17.
The adjusting lever 21 is made to protrude outside the pressure regulating valve box 24, and the adjusting lever 21 is rotated to close the stopper 18.
For example, if the stopper 18 is moved further away from the valve stem 20 by adjusting the movement, the stroke until the valve stem 20 comes into contact with the stopper 18 becomes larger, and the flow from the valve chamber 15 to the valve chamber 23 of the one-hour relief valve 17 increases. Since the amount of pressure oil escaping increases, the above-mentioned range in Fig. 4
As R ₁ increases, the rise of the pressure oil in the PTO clutch cylinder 5 becomes more gradual, and the rise of the rotational speed of the PTO shaft also becomes more gradual.Conversely, if the stopper 18 is brought closer to the valve stem 20, the above stroke will be reduced. As it becomes shorter, the amount of oil escaping from the valve chamber 15 to the valve chamber 23 decreases, and therefore the range _R1 becomes smaller, and the rise of the pressure oil in the PTO clutch cylinder 5 and the rotation speed of the PTO shaft become faster. Configure.

Further, in FIG. 3, reference numeral 26 is a switching arm of the PTO clutch switching valve 4, which is switched by a clutch operating lever 27.
Further, the pressure regulating valve box 24 is mounted on the transmission case 28. Further, as shown in FIG. 1, the pressure oil of the pump 1 is also supplied to the cylinder 31 of the lift mechanism 30 via the control valve 29.
Therefore, when the PTO clutch switching valve 4 is switched to the clutch connection position, the valve body 12 of the boost control valve 7 moves left and right little by little to release the pressure oil from the pump 1 to the tank 2, or the PTO clutch cylinder Since the operation of supplying the gas to the tank 2 is repeated alternately, the pressure increase inside the PTO clutch cylinder 5 is slowed down by the relief operation to the tank 2.

The pressure oil supplied to the valve chamber 15 to interrupt this relief operation is supplied to the 1 hour relief valve 17.
Therefore, while the action of the one-hour relief valve 17 continues, the pressure increase in the PTO clutch cylinder 5 becomes more gradual, and the pressure increase control shown in FIG. Valve 7
When compared with the dotted line pressure curve F ₂ showing the pressure increase in the PTO clutch cylinder 5 when using a conventional flow divider without the 1-hour relief valve 17, the pressure curve when using the inventive device As shown in F ₁ , this PTO
The rotational speed of the PTO shaft to which rotational force is transmitted by the clutch piston 27 of the clutch cylinder 5 is a rotational speed curve S1 using the device of the present invention, compared to a rotational speed curve _S2 using the conventional flow divider shown in _FIG . shows a gradual rise.

and PTO in the range R ₁ in the pressure rise diagram
The oil pressure increase rate of the clutch cylinder 5 can be adjusted to any desired size by rotating the adjustment lever 21 of the one-hour relief valve 17. If it is moved rearward, the amount of pressure oil escaping to the one-hour relief valve 17 will increase, so the oil pressure in the PTO clutch cylinder 5 will increase more slowly, and the PTO shaft will gradually increase its rotational speed. As a result, when driving the working part of the work equipment, the PTO
By slowing down the rise in the pressure oil supplied to the clutch cylinder, the rotational speed of the PTO shaft can be gradually increased, making it suitable for driving working machines such as mowers that have large inertia. As a result, the impact force acting on the power transmission system can be sufficiently alleviated, and wear and tear on various parts can be effectively prevented.

When a working machine with a small inertia of the working part is connected, the hydraulic pressure of the PTO clutch cylinder 5 can be increased by rotating the adjustment lever 21 so as to move the stopper 18 closer to the valve stem 20. can be adjusted so that the
The rise in rotational speed of the PTO shaft also becomes faster.

The PTO clutch hydraulic pressure control device according to the present invention is configured as described above, and controls the hydraulic pressure increase of the PTO clutch cylinder 5 by two valves, the pressure increase control valve 7 and the one-hour relief valve 17. Since the number of valves is smaller than that of known valve devices, the related operations between the valves are simple, consistent, and accurate. This made it possible to significantly reduce costs.

Moreover, the device of the present invention supplies the working pressure oil supplied to the PTO clutch cylinder 5 to the valve chamber 13 on the return side of the valve body 12 of the boost control valve 7 that controls the supply pressure, and the valve on the return prevention side. The capacity of the valve chamber 23 of the one-hour relief valve 17, which is provided to supply pilot pressure to both chambers 15 and adjust the pilot pressure in the valve chamber 15 on the return prevention side, is provided so as to protrude outward. By adjusting the adjusting screw 22, the rising speed of the hydraulic pressure can be freely adjusted, so as mentioned above, the rate of increase in the rotational speed of the PTO shaft can be adjusted according to the magnitude of the inertia of the working part of the working machine being used. can be set to a proper value, and by this
This made it possible to start work more efficiently while reducing the impact that is applied to the PTO shaft and working parts when the clutch is engaged.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of the device according to the invention, Fig. 2 is a vertical sectional view of a pressure regulating valve box used in the above device, Fig. 3 is a side view showing the installation state of the above device, and Fig. 4 is a
Pressure rise diagram of hydraulic pressure in PTO clutch cylinder,
Figure 5 is a diagram showing the increase in rotational speed of the PTO shaft. Explanation of symbols, 1...pump, 2...tank, 3...
...Relief valve, 4...PTO clutch switching valve, 5
...PTO clutch cylinder, 6, 14... Throttle, 7... Boost control valve, 8, 9... Oil passage, 10... Return port, 11... Blocking part, 12
... Valve body, 13, 15, 23 ... Valve chamber, 16, 1
9... Spring, 17... 1 o'clock relief valve, 18... Stopper, 20... Valve stem, 21... Adjustment lever, 2
2... Adjustment screw, 24... Pressure regulating valve box, 25... Flow divider, 26... Switching arm, 27... Clutch operation lever, 28... Mission case,
29...Control valve, 31...Cylinder, 30...Lift mechanism, F1 _{, F2} ...Pressure curve, _P1 , _P2 ...Pressure, _R1 , _R2 ...Range, _S1 , _S2
...rotation speed curve.

Claims (1)

[Claims] 1 The valve body 1 is connected so that the return port 10 of the valve body 12 of the boost control valve 7 communicates with the tank 2 the working pressure oil to be supplied to the PTO clutch cylinder 5.
2 and the valve chamber 13 on the return side that pushes the valve body 1
A valve chamber 1 on the return prevention side that pushes this valve body 12 so that the closing part 11 of No. 2 closes the return to the tank 2.
5 through throttles 14, and an oil passage to the valve chamber 15 on the return prevention side is also formed in communication with the valve chamber 23 of the one-hour relief valve 17, so that the pressure oil of the PTO clutch cylinder 5 is Return port 10 as oil pressure increases
The valve body 12 is moved so that the closing portions 11 and 11 are alternately connected to the tank 2, and the 1 o'clock relief valve 17 is moved.
A hydraulic pressure control device for a PTO clutch is provided so that the capacity in the valve chamber 23 can be adjusted by an adjustment screw 22 protruding from the outside of the one-time relief valve 17.