JPS641493Y2 - - Google Patents

Description

[Detailed description of the invention] A concrete pump that delivers liquid concrete to a predetermined location uses a sequence valve to supply pressure oil to a hydraulic cylinder that operates the concrete cylinder and a valve cylinder that operates the concrete cylinder valve. I'm trying to switch between them.

To stop a conventional concrete pump, the pressure oil supply line (corresponding to 6 in Figure 1) is communicated with the tank via a safety valve (corresponding to 18 in Figure 1) to reduce the piping pressure of the pressure oil supply line. I'm going by this. However, this vent-off pressure (piping pressure when the pressure oil supply pipe is connected to the tank) does not become zero due to the aforementioned flow path resistance of the piping, the resistance of the safety valve and the piping from the safety valve to the oil tank, etc. Particularly in cold weather, the viscosity of the hydraulic oil increases, so the residual pressure increases. At this time, the pressure within the accumulator 13 is maintained by the check valve 8, so the sequence valve 11 remains open.

Therefore, if the concrete is soft or the concrete piping is short, that is, the load is small,
The hydraulic cylinders 3 and 4 for operating the concrete cylinders move due to the residual pressure in the pipe 6. Even if the operator intends to turn off the switch and stop the pump, concrete will be discharged, which is extremely dangerous.

The present invention was developed to solve this problem by branching the pressure oil piping at a predetermined position, connecting one of the branches to a hydraulic cylinder for operating a concrete cylinder, and connecting the other to a hydraulic cylinder for operating a valve. A sequence valve is installed in the branch pipe on the side of the concrete cylinder operating hydraulic cylinder, and in order to apply switching operating pressure to the sequence valve, the branch pipe on the valve operating hydraulic cylinder side and the sequence valve are connected by a signal pipe, and the same pressure is applied. In a hydraulic circuit that can alternately supply pressure oil from an oil source to a concrete cylinder operating hydraulic cylinder and a valve operating hydraulic cylinder,
The signal pipe is characterized in that the signal pipe is provided with a switching valve that opens or closes the signal pipe in conjunction with an operation to stop the hydraulic cylinder.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an embodiment of the present invention, and shows a hydraulic circuit for driving a double-acting concrete pump equipped with two sets of concrete cylinders for feeding concrete.

In the figure, numerals 1 and 2 are valve cylinders that operate valves to cause the concrete cylinder to alternately discharge and suck concrete, and numerals 3 and 4 are hydraulic cylinders that operate the concrete cylinders.

The pipe 6 connected to the pressure oil source 5 is branched at point A,
One branch pipe 7 is connected to the valve cylinders 1 and 2 via a check valve 8 and a hydraulic switching valve 9, and the other branch pipe 1
0 is connected to hydraulic cylinders 3 and 4 via a sequence valve 11 and a hydraulic switching valve 12. Said hydraulic switching valve 9
An accumulator 13 is connected between the accumulator 13 and the sequence valve 11, and a solenoid valve 14 is connected to the accumulator 13 and the sequence valve 11 through a signal pipe 15, and the signal pipe 15 and the hydraulic switching valves 9 and 12 are connected to each other as an electromagnetic switching valve. 1
6, and further connected to the electromagnetic switching valve 1 of the signal pipe 15.
A throttle valve 17 is provided at a position closer to the accumulator 13 than the connection point 6. Further, a safety valve 18 and a solenoid valve 19 are sequentially connected in the middle of the pipe 6, and limit switches LS ₁ and LS ₂ are provided in the hydraulic cylinders 3 and 4, respectively, to detect the end of stroke of the hydraulic cylinders 3 and 4,
The limit switches LS ₁ and LS ₂ are electrically connected to the electromagnetic switching valve 16, and the electromagnetic valves 14 and 19 are connected electrically.
The electric circuit shown in Fig. 2 is connected to. Furthermore, the first
In the figure, 20 is the oil tank, in Figure 2, SW is the main switch of this concrete pump, PR is the normally open type relay, T is the timer, PR ₁ and PR ₂ are the relay contacts, T ₁ is the timer contact, SoL ₁ indicates the solenoid of the electromagnetic valve 14, and SoL ₂ indicates the solenoid of the electromagnetic valve 19.

Next, the operation of this hydraulic circuit will be explained.

First, the main switch SW is turned on and the solenoid valve 19 is operated to shut off the pipe 6 and the oil tank 20, and at the same time, pressure oil is supplied from the pressure oil source 5. At the start of operation, the pressure in the signal pipe 15 has not increased, so the sequence valve 11 is in a closed state, and the pressure oil flows through the check valve 8,
It reaches the valve cylinders 1 and 2 via the hydraulic switching valve 9, and operates the valve cylinders 1 and 2 to move the valve (not shown) to a predetermined position. After operating the valve cylinders 1 and 2, the pressure oil is stored in the accumulator 13 and transferred to the branch pipe 7.
Increase system pressure. When the pressure in the branch pipe 7 increases, the sequence valve 11 operates and pressure oil is supplied to the hydraulic cylinders 3 and 4 via the hydraulic switching valve 12, and the hydraulic cylinders 3 and 4 and the concrete pistons connected to the cylinders 3 and 4 (Fig. (not shown). Assuming that the hydraulic switching valves 9 and 12 are in the state shown in the figure, the pistons 21 and 21 of the valve cylinders 1 and 2
The movable parts such as the above move to the left, the piston 22 and the like of the hydraulic cylinder 3 move upward, and the piston 23 and the like of the hydraulic cylinder 4 move downward. When the piston 22 of the hydraulic cylinder 3 reaches the upper stroke end and activates the limit switch LS ₁ , the electromagnetic switching valve 16 is energized and the hydraulic switching valves 9, 12 are activated.
Pressure oil is supplied for switching. When pressure oil is supplied to the hydraulic switching valves 9 and 12, the hydraulic switching valves 9 and
12 switches and the pressure inside the signal pipe 15 changes to the throttle valve 1.
7, the sequence valve 11 returns and the branch pipe 10 is cut off, and the pressure oil is fed to move the pistons 21, 21 of the valve cylinders 1, 2 to the right. The pressure in the signal pipe 15 increases, the sequence valve 11 operates again, and the hydraulic cylinder 4
Pressure oil is supplied to move the piston 23 of the hydraulic cylinder 3 upward and the piston 22 of the hydraulic cylinder 3 downward. Therefore, this concrete pump will operate continuously.

Next, when the main switch SW is turned off to stop the concrete pump, the relay PR is turned off.
The contacts PR ₁ and PR ₂ close, and the timer T becomes energized, closing the contact T ₁ for a certain period of time. Therefore, when the solenoid valve 19 is driven, the solenoid SoL ₂ is de-energized, the solenoid SoL ₁ that drives the solenoid valve 14 is energized for a certain period of time, and the pipe 6 is opened and communicated with the oil tank 20, and the signal pipe 15 is opened. It is in communication with the oil tank 20. For this reason, the supply of pressure oil from the pressure oil source 5 to the branch pipes 7 and 10 is stopped, and the pressure in the signal pipe 15 decreases due to the operation of the solenoid valve 14, which causes the sequence valve 11 to return instantaneously and supply the branch pipes. 10 and stops the hydraulic cylinders 3 and 4. Therefore, the hydraulic switching valves 9 and 12 are not in the same state, and the branch pipe 10 is disconnected by the sequence valve 11, so the supply of pressure oil to the hydraulic cylinders 3 and 4 is cut off, and the hydraulic cylinders 3 and 4 are immediately turned off. The system will be stopped and the supply of concrete will also be stopped. As mentioned above, vent pressure remains in the pipe 6 due to the pipe resistance and the resistance of the safety valve 18, but since the sequence valve 11 is closed by the action of the solenoid valve 14 and the branch pipe 10 is disconnected,
The hydraulic cylinders 3 and 4 for concrete cylinders are not driven.

In the above embodiment, the signal pipe 15 for guiding the operating pressure of the sequence valve 11 was opened and closed by the solenoid valve 14, but this switching is performed by closing the signal pipe 15 by the solenoid valve 24 as shown in FIG. Sequence valve 1
1 may be opened to the tank side. In that case, the electrical circuit diagram will be as shown in FIG.

Further, although the above embodiment is an example in which the present invention is applied to a concrete pump, the present invention is not limited to concrete pumps, and can be applied to any type of pump that includes a first hydraulic cylinder and a second hydraulic cylinder and operates both of them alternately by a sequence valve. For example, it goes without saying that the present invention can also be applied to a pump that pumps highly viscous substances other than concrete, such as silt, earth and sand, sludge, unmixed material, etc.

As described above, according to the present invention, since the pressure in the signal pipe for operating the sequence valve is actively lowered in conjunction with the stop operation of the hydraulic cylinder, unexpected concrete feeding after the stop operation can be avoided. can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram including a sequence valve control circuit according to the present invention, Fig. 2 is an electric circuit diagram connected to a solenoid valve of the hydraulic circuit of Fig. 1, and Fig. 3 is a diagram of another embodiment. The sequence valve control circuit diagram shown in FIG. 4 is an electric circuit diagram in this other embodiment. 1 and 2 are valve cylinders, 3 and 4 are hydraulic cylinders,
6 is a pipe, 7 and 10 are branch pipes, 11 is a sequence valve, 14 is a solenoid valve, and 15 is a signal pipe.

Claims (1)

[Scope of utility model registration request] The pressure oil pipe is branched at a required position, one of the branches is connected to a hydraulic cylinder for operating a concrete cylinder, and the other is connected to a hydraulic cylinder for valve operation, and a sequence valve is further provided in the branch pipe on the side of the hydraulic cylinder for operating the concrete cylinder. In order to apply switching pressure to the sequence valve, the branch pipe on the valve operating hydraulic cylinder side and the sequence valve are connected by a signal pipe, and pressure oil from the same pressure oil source is applied to the concrete cylinder operating hydraulic cylinder and the sequence valve. In a hydraulic circuit capable of alternately supplying power to hydraulic cylinders for valve operation, the signal pipe is provided with a switching valve that opens or closes the signal pipe in conjunction with an operation to stop both hydraulic cylinders. Features a sequence valve control circuit.