JPH034788Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention uses a switching valve that switches the flow path of the transported material when it is sucked in and discharged by a pump, such as concrete or earth, and blocks the flow path. This invention relates to an automatic blockage prevention device for a pump to prevent such problems.

[Conventional technology]

As an example, to explain the case of a concrete pump, there are two types of flow path switching valves for concrete pumps: an oscillating type and a gate valve type, and the oscillating type concrete pump is schematically shown in Figs. 3 and 4. As shown in FIG.
Inside, a swinging tube 6 is disposed, one end of which is connected to the transport pipe 5 outside the hopper 1, and the opening of the other end alternately communicated with either one of the pair of transport cylinders 3, 4. Then, the swing tube 6 is fixed to a swing shaft 7 which is rotatably supported by the hopper 1, and also fixed via a connecting plate 8, and the swing shaft 7 is alternately moved to the right or left. By rotating the
The swing tube 6 is configured to be able to swing left and right around a swing axis X. Furthermore, the two transport cylinders 3 and 4 are provided with two main hydraulic cylinders 10 and 11.
are connected via a cleaning box 12, and pistons 13, 1 are slidably housed in transport cylinders 3, 4.
4 and pistons 15 and 16 housed in the main hydraulic cylinders 10 and 11, respectively, are connected to one piston rod 1.
7 and 18, and by reciprocating the main hydraulic cylinders 10 and 11 alternately, the transport cylinders 3,
4 are arranged to reciprocate at the same time. Therefore, when the concrete 9 in the hopper 1 is sucked into one of the transport cylinders 3 and 4 that alternately reciprocate, the other transport cylinder is in communication with the swing pipe 6 and the concrete 9 is drawn into the other transport cylinder. The concrete that had been sucked into the pipe is discharged through the swing pipe 6,
The concrete in the hopper 1 can be sequentially sucked in and discharged by the alternate suction and discharge operations of the two transport cylinders 3 and 4 and the swing operation of the swing tube 6.

A hydraulic control circuit as shown in FIG. 5 is constructed so that the reciprocation of the transportation cylinders 3 and 4 by the main hydraulic cylinders 10 and 11 and the swinging of the swinging tube 6 are related. When the flow path is switched by swinging the main hydraulic cylinder, the main hydraulic cylinder is switched. That is, the valve drive cylinder 19 and the main hydraulic cylinders 10 and 1 connected to the drive shaft 7 in FIG.
1, the hydraulic circuit that operates the main hydraulic cylinders 10 and 11 and the hydraulic pump 20 are connected to a pressure oil line 21 having a four-way valve 22 and a check valve 23 in the middle, as shown in an example in FIG. and connect,
The valve drive cylinder 19 and the hydraulic pump 24 are connected by a pressure oil line 25 having a four-way valve 26 and a check valve 27 on the way, and an accumulator 28 is installed on the upstream side of the four-way valve 26 in the pressure oil line 25.
are connected. In addition, the main hydraulic cylinders 10, 11
The pistons have pilot switching valves 29 and 30 that operate when the main hydraulic pistons 15 and 16 reach the stroke end on each rod side, and the pilot switching valves 2.
When 9 and 30 are switched, a boost valve 31 which is switched by pilot pressure and a reversing valve 32 and 3
3, and an electromagnetic switching valve 34 for applying pilot pressure to the pilot switching valves 29 and 30, and the electromagnetic switching valve 34 is connected to the pressure oil line 25,
Pilot circuit 3 with orifice 36 in the middle
5, and by switching the electromagnetic switching valve 34 from port A to port B, the pressure oil line 25 is connected to the pilot switching valves 29, 30, and the pilot switching valves 29, 30 are connected to the boost valve 31 via the reversing valve 32. The boost valve 31 is connected to the four-way valve 22 of the pressure oil line 21 via the reversing valve 33 and simultaneously connected to the four-way valve 26 of the pressure oil line 25.

37 is a sealed circuit, 38 is a line for replenishing the sealed circuit 37 with pressure oil from the pressure oil line 25, and has a stop 39 in the middle and a safety valve 40.
is provided. Note that an ordinary valve may be used instead of the electromagnetic switching valve 34.

Now, when the pumps 20 and 28 are driven, pressure oil is supplied to the head side of the main hydraulic cylinder 11 and simultaneously to the head side of the valve drive cylinder 19.
The main hydraulic cylinder 11 operates in the extension direction, and the main hydraulic cylinder 10 operates in the contraction direction to suck and discharge concrete through the transport cylinder, and at the same time, the valve drive cylinder 19 switches the suction and discharge valves. When the main hydraulic cylinder 11 reaches the stroke end, the pilot switching valve 30 is switched, and during automatic operation, the electromagnetic switching valve 34 is switched to port B.
As a result, the pilot pressure passes through the line 41 and pushes the boost valve 31 to the right in the figure, thereby causing the switching. As a result, the separately supplied pressure oil passes through the line 42, the boost valve 31, and the line 43, pushes the four-way valve 26 of the pressure oil line 25 to the left in the figure, and switches the flow path, and at the same time, the pressure oil passes through the line 44. Push the four-way valve 22 of the oil line 21 overhead to the left to switch. As a result, the pressure oil from the pump 20 is supplied to the head side of the main hydraulic cylinder 10, and the pressure oil from the pump 24 is supplied to the rod side of the valve drive cylinder 19. 45 is an unload valve for unloading the accumulator 28 when the pressure reaches a certain level in the drive circuit that moves the valve drive cylinder 19;
46 is a solenoid switching valve 47 that can be switched by energizing or demagnetizing the solenoid SOL1. When the solenoid SOL1 is energized or demagnetized, the solenoid switching valve 47 releases the pressure oil in the pressure oil line 21 to the tank 48. When the solenoid SOL1 is energized, the pressure oil in the pressure oil line 21 is released to the tank 48. When the solenoid SOL1 is energized, it enters the load state and transfers the pressure oil to the main hydraulic cylinder 1.
0 and 11 are safety valves that lead to the side.

[Problem that the invention attempts to solve]

However, in the conventional pump described above, the suction and discharge of concrete is switched via the transport cylinders 3 and 4 by the pressure of the main cylinders 10 and 11, and at the same time, the swing pipe 6 is oscillated by the valve drive cylinder 19, and the suction and discharge are changed. Although the outlet 2 is switched, the reality is that it is not confirmed whether the swing tube 6 has been reliably switched from one of the two suction and discharge ports 2 to the other. Therefore, the valve drive cylinder 1
When the swing pipe 6 is switched by 9, the main hydraulic cylinders 10 and 11 are switched and move to concrete suction and discharge operation. , 11 are activated, there is a problem that the suction and discharge ports 2 are clogged with objects to be transported such as concrete, and the swing tube 6 does not match the suction and discharge ports 2, causing the transportation cylinders 3 and 4 to be operated even in a half-open state. It was hot. That is, among the swing valves, transportation cylinders 3, 4, and main hydraulic cylinders 10, 11 that make up the pump, if the swing valve made up of the swing tube 6 is not completely switched, the valve will close the flow path of the transported object. occlusion, making pumping impossible (called pseudo-occlusion). If pressure-feeding continues as it is, the water in the transported material necessary for transportation will dehydrate, causing complete blockage, and it will become impossible to continue pumping unless the blockage is removed.

Therefore, in the present invention, the main hydraulic cylinder operates only after it is confirmed that the swing valve has been reliably switched, and if the swing valve does not switch after a certain period of time, the valve drive cylinder is activated. This is intended to prevent the risk of clogging the flow path of the transported object by operating the main hydraulic cylinder in the reverse direction.

[Means for solving problems]

The present invention provides a switch at the stroke end of the valve drive cylinder to detect when the piston of the valve drive cylinder has reached the stroke end, and also switches the oil path in the middle of the valve drive cylinder side pressure oil line to reverse the flow. In addition, a timer is provided to set the time until the piston of the valve drive cylinder reaches the stroke end, and to start counting from the start of valve switching to monitor the switching time. is connected to reset the timer setting when the switch is activated, and is also connected so that when the switch is activated, the electromagnetic switching valve in the main hydraulic cylinder side pressure oil line is energized, and also to reset the timer setting time. There is a relay that operates when the valve does not switch even when the pressure exceeds the limit, and becomes inactive when the timer is reset by the operation of the switch, and a relay that demagnetizes the electromagnetic switching valve in the middle of the main hydraulic cylinder side pressure oil line when the relay operates. Further, the configuration includes an electric circuit that excites the electromagnetic switching valve in the middle of the valve drive cylinder side pressure oil line and issues an alarm at the same time.

[Effect]

In the case of normal operation in which the valve drive cylinder operates and the swing valve is completely switched within the time set by the timer,
The switch that detects the movement of the piston in the valve actuating cylinder is activated, so the timer remains reset, and the electromagnetic switching valve in the middle of the main hydraulic cylinder side pressure oil line is energized, so that the main hydraulic cylinder alternates. It continues its reciprocating motion and sucks and discharges the transported object.

If the timer setting time elapses without the valve drive cylinder reaching the stroke end, this means that the hopper's suction and discharge ports are clogged with material to be transported and the swing valve is half-open, causing pressure feeding to be temporarily interrupted. When the set time of the timer is exceeded, the output relay is activated and the electromagnetic switching valve in the main hydraulic cylinder side pressure oil line is demagnetized, and at the same time, the electromagnetic switching valve in the middle of the valve drive cylinder side pressure oil line is energized to reduce the pressure. Reverse the oil line and reverse the valve drive cylinder. When the switch is actuated by this reversal, the timer setting is reset, the same operation as in the normal operation is performed, pressure feeding is resumed, and blockage is prevented.

〔Example〕

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

FIG. 1 shows one embodiment of the present invention.
The hydraulic control circuit configuration is similar to that of the conventional pump shown in the figure, and the valve drive cylinder 19
The tip of the piston rod 49 is connected to a lever 50 that is integrated with the swing shaft 7, and the swing tube 6 swings from side to side about the swing shaft 7 by the reciprocation of the valve drive cylinder 19, and the swing valve In a configuration in which the piston rod is alternately switched to the suction and discharge port 2, a striker 51 is attached to the tip of the piston rod 49 of the valve drive cylinder 19, and is installed at each stroke end on the expansion side and compression side of the valve drive cylinder 19. Connect the limit switches LS ₁ and LS ₂ to the above striker 51.
Furthermore, in the middle of the pressure oil line 25 to the valve driving cylinder 19, that is, between the four-way valve 26 and the valve driving cylinder 19,
An electromagnetic switching valve 52 is provided which switches the pressure oil line 25 to the reverse direction by switching between energization and demagnetization of the solenoid SOL ₂ .

An electric circuit for automatically energizing and demagnetizing the solenoids SOL ₁ and _{SOL 2 in} connection with the activation and deactivation of the limit switches LS ₁ and LS 2 is constructed as shown in FIG.

In Fig. 2, 53 is a timer, which is connected to the circuits of limit switches LS ₁ and LS ₂ , and interrupts and resets the relay output and counting when both or one of the limit switches LS ₁ and LS ₂ is ON. , the timer starts counting when both LS ₁ and LS ₂ are OFF.
SW ₁ is the power switch for the timer element, and SW ₂ is the pump operation switch, which must be turned on when the pump is running.
It is something to keep. VR ₁ is a variable resistor that changes the set time of the timer 53 to preset the normal switching time of the swing valve, R ₁ is a relay, and even if the set time of the timer has elapsed, the limit switch LS ₁ ,
It is activated by the timer output when LS ₂ is OFF. L ₁ is a warning lamp, BZ is a buzzer.

Now, when starting the operation of the pump when transporting materials such as concrete under pressure, turn on the pump operation switch SW ₂ and turn on the power switch SW ₁ .

Next, the hydraulic pumps 20 and 24 in the hydraulic control circuit shown in FIG. Activate. The operating procedure for operating the main hydraulic cylinders 10, 11 and the valve drive cylinder 19 is as described above with reference to FIG.

During pump operation, during normal operation when the valve drive cylinder 19 operates reliably and the swing valve consisting of the swing tube 6 completely switches the suction and discharge port 2, the limit switches LS ₁ and LS ₂ alternately switch to the striker. 5
1, the timer 53 remains reset and there is no output to the relay _R1 , so the relay _R1 remains inoperative. Therefore,
In Figure 2, the b contact R ₁ b of relay R ₁ remains closed, so solenoid SOL ₁ is energized.
The electromagnetic switching valve 47 in FIG. 1 is in a state switched from the state shown, and pressure oil from the pump 20 continues to be sent to the main hydraulic cylinders 10, 11 via the pressure oil line 21 and the four-way valve 22.

If the swing valve is slow to switch or does not switch completely, such as when the swing valve does not switch completely and stops midway, limit switch LS ₁ or LS ₂ should be activated. First, the set time of the timer 53 has elapsed, so the output of the timer 53 is activated, the B contact R ₁ b opens, and the A contact R ₁ a ₁
closes. As a result, the solenoid SOL ₁ is demagnetized and the electromagnetic switching valve 47 returns to the state shown in FIG.
Pressure oil is no longer sent to the tank, and suction and discharge of the transported object stops. At the same time, the solenoid SOL ₂ is energized, so the electromagnetic switching valve 52 is switched from the state shown in FIG. It is sent to the cylinder 19, and the valve driving cylinder 19 is reversed (if it is in the middle of extension, it is moved in the shortening direction, and if it is in the middle of shortening, it is moved in the extending direction).

Since the a contact R ₁ a ₂ also closes at the same time as each of the above operations,
Alarm lamp _L1 lights up to issue an alarm, and buzzer BZ also begins to sound.

In each of the above operations, when the valve drive cylinder 19 reverses during operation and reaches the stroke end, the striker 51 switches the limit switch LS _1.
Or, by hitting LS ₂ , timer 53 is reset. When the timer 53 is reset, the relay
R ₁ becomes inactive and its b contact R ₁ b closes,
Both a contacts R ₁ a ₁ and R ₁ a ₂ open. As a result, the solenoid SOL ₁ is energized and the electromagnetic switching valve 47 is switched from the state shown in FIG.
At the same time, the solenoid SOL ₂ is demagnetized and the solenoid switching valve 52 is automatically switched to the position shown in FIG. return to the state of
The valve drive cylinder 19, which has been reversed, returns to its original position. During this time, the cause of the switching failure of the swing valve is removed, so that the swing valve can operate normally within the specified time.

Although the above explanation mainly deals with concrete pumps, it goes without saying that the same applies to any pump that sucks in earth and sand or other materials to be transported, and also applies to the piston rod of the valve drive cylinder 19. 49, and the striker 51 strikes the limit switches LS ₁ and LS ₂ at the end of the stroke to operate them. Alternatively, for example, a proximity switch that does not come into contact with the striker 51 may be used, or the proximity switch may be provided within the tube of the valve drive cylinder 19 and a magnet may be attached to the piston. Furthermore, the electromagnetic switching valve 52 may be incorporated upstream of the four-way valve 26.

[Effect of idea]

As described above, according to the automatic blockage prevention device for a pump of the present invention, the switching time of the swing valve is monitored, and when the valve does not switch even after a predetermined period of time has elapsed, the system automatically controls the Pressure feeding is temporarily interrupted, the valve is reversed, and then the valve is returned to normal operation, and pressure feeding of the transported material is automatically restarted, so the risk of blockage is eliminated before the flow path of the transported material is completely blocked. It is possible to prevent this from happening, prevent the pumping from becoming impossible, and furthermore, there is no need for a person to constantly monitor the blockage, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a hydraulic control circuit diagram showing an embodiment of the automatic blockage prevention device for a pump of the present invention, and FIG. 2 is an electrical circuit diagram of the automatic blockage prevention device for a pump of the present invention.
FIG. 3 is a cutaway side view showing an example of the pump, FIG. 4 is a view taken along the - arrow in FIG. 3, and FIG. 5 is a hydraulic control circuit diagram for conventional pump operation. 1 is a hopper, 2 is a suction and discharge port, 3 and 4 are transport cylinders, 6 is a swing pipe, 10 and 11 are main hydraulic cylinders, 19 is a valve drive cylinder, 20 and 24 are hydraulic pumps, and 21 and 25 are pressure feeding lines , 22 and 26 are four-way valves, 46 is a safety valve, 47 is an electromagnetic switching valve, 51 is a striker, 52 is an electromagnetic switching valve, and 53 is a timer.

Claims (1)

[Scope of utility model registration request] A switch is provided at the stroke end of the valve drive cylinder that drives the swing valve, and an electromagnetic switching valve is provided in the middle of the pressure oil line connected to the valve drive cylinder to switch the oil path to the reverse direction. An electromagnetic switching valve is provided for unloading and loading a safety valve in the middle of the pressure oil line connected to the main hydraulic cylinder for discharge, and a timer is also provided to set the switching time of the swing valve.
The above switch and a timer are connected in order to reset the timer when the switch is activated, and the timer is activated when the valve does not switch even after the set time of the timer is exceeded, and the timer is reset by the operation of the above switch. When the relay is activated, it demagnetizes the electromagnetic switching valve in the main hydraulic cylinder side pressure oil line and energizes the electromagnetic switching valve in the valve drive cylinder side pressure oil line, and conversely, the relay becomes inoperable. The automatic pump is characterized in that it is equipped with an electric circuit incorporating a contact point that energizes the electromagnetic switching valve in the pressure oil line of the main hydraulic cylinder and demagnetizes the electromagnetic switching valve in the side pressure oil line of the valve driving cylinder. Anti-occlusion device.