JPS6339727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a pneumatic improvement material supply device in a soft ground improvement machine.

Pneumatic powder feeding equipment is widely used in the field of transporting various types of powder, but this means that it is only transported in the atmosphere, and this powder feeding equipment is used to improve soft ground by supplying improving materials. There are no practical examples of application to machines. That is, in a pneumatic conveyance type supply device for cement slurry, the discharge amount of the slurry pump is usually controlled by comparing the penetration or withdrawal speed of the agitator with a set discharge value. However, in the case of pneumatic conveyance of soil improvement material, it is necessary to minimize the amount of air, keep the amount of improvement material discharged per unit volume of soft soil constant even if the depth changes, and make sure that the improvement material is Make sure that there is no blockage in the middle of the hose. In other words, in soil improvement, a major problem is how to evenly discharge the improvement material, and this determines the magnitude of the strength variation after discharge. If a conventional pneumatic conveyance type feeding device is applied to a soft ground improvement machine as is, the amount of improvement material discharged will be small in deep areas and increase in shallow areas.As a result, the strength of improvement in deep areas will be weak, and if it becomes shallow, There was a problem that the strength became stronger and the strength variation in the depth direction became larger.

In this way, conventional pneumatic conveyance technology transports a fixed amount of objects from the atmosphere to the atmosphere within a certain period of time. The technology for improving soft ground had not been established, and it could not be used in soft ground improvement machines.

As a result of repeated experiments to satisfy these conditions, the present invention has shown that if the rotation speed of the feeder that discharges the improved material is kept constant, even if the pressure at the end of the conveyance changes, the wind speed inside the conveyor exit hose can be maintained. This method focuses on the fact that by setting the value above a certain value, it is possible to maintain an instantaneous discharge amount proportional to the rotation speed of the feeder.The first feature is that the improved material in the improved material tank is In a pneumatic improvement material supply device for a soft ground improvement machine that transports the improvement material to the agitator by compressed air via a feeder, calculate the instantaneous discharge amount of the improvement material conveyed from the improvement material tank to the agitator, A discharge rate control means that controls the feeder to match this with the instantaneous discharge rate set value, and a discharge rate control means that calculates the secondary wind speed in the hose from the feeder to the agitator, and adjusts it to the minimum secondary wind speed set value. The second feature is that the improved material in the improved material tank is transferred to the agitator using compressed air via the feeder. In the pneumatic improvement material supply device of the soft ground improvement machine, the instantaneous discharge amount of the improvement material conveyed from the improvement material tank to the agitator is calculated, and this is adjusted to the instantaneous discharge amount setting value. A discharge rate control means that controls the feeder, and a secondary air flow controller that calculates the secondary wind speed in the hose leading from the feeder to the agitator and controls the pressure regulating valve on the primary side to match this with the minimum secondary air speed setting value. The present invention is characterized by comprising: a wind speed control means; and a mixture ratio control means for calculating the mixture ratio of the improvement material and air and controlling the pressure regulating valve so as to make the mixture ratio equal to or less than a set maximum mixture ratio.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. In the figure, 1 is an improved material tank for storing improved material, 2 is a feeder for discharging the improved material from the improved material tank 1, and a variable speed motor is used. 3. Reference numeral 4 indicated by a double line is a hose for pneumatically transporting the improved material discharged from the feeder 2 to the deep mixer using compressed air supplied from the air compressor. On the primary side of the hose 4, that is, on the upstream side of the feeder 2, a pressure regulating valve 5 and an on-off valve 6 are interposed in series, and a primary pressure transmitter 29 and an air flow transmitter 7 are attached. There is. Also, the secondary side of the hose 4, that is, the feeder 2
On the downstream side, an on-off valve 8 and a secondary pressure transmitter 9 are installed.
is provided. Reference numeral 10 denotes a bypass valve, which is connected in parallel to the feeder 2 and the on-off valve 6. Reference numeral 11 denotes a discharge amount control means, which includes a plurality of load cells 12 that support the improvement material tank 1, an adder 13 that adds the outputs of each load cell, an instantaneous discharge amount calculator 14 that calculates the instantaneous discharge amount from the added output, and an instantaneous discharge amount calculator 14 that calculates the instantaneous discharge amount from the added output. An instantaneous discharge amount setter 15 for setting the discharge amount, a deviation calculator 16 and an amplifier 17 for comparing the instantaneous discharge amount with a set value.
The variable speed motor 3, that is, the rotation speed of the feeder 2 is controlled so that the instantaneous discharge amount matches the instantaneous discharge amount set value. 18 is a secondary wind speed control means, which controls the primary pressure P ₁ from the primary pressure transmitter 29 and the primary air amount Q ₁ from the air flow rate transmitter 7.
and the secondary pressure P ₂ from the secondary pressure transmitter 9 and from 2
A secondary wind speed calculator 19 that calculates the secondary wind speed _V2 , a minimum secondary wind speed setting device 20, 2 that sets the minimum secondary wind speed
A deviation calculator 21 and an amplifier 22 are provided to compare the secondary wind speed _V2 and the minimum secondary wind speed set value,
The pressure regulating valve 5 is configured to control the pressure regulating valve 5 to adjust V ₂ to the minimum secondary wind speed setting value. Note that the primary air temperature T ₁ is a factor in calculating the secondary wind speed V ₂
and secondary air temperature _T2 may be added. 23 is a mixing ratio control means, which calculates the mixing ratio (improved material weight/air weight) based on the instantaneous discharge amount and the air weight W ₂ obtained from the secondary pressure P ₂ and the secondary wind speed V ₂ . A ratio calculator 24, a maximum mixing ratio setter 25 that sets the maximum mixing ratio, a deviation calculator 26 that compares the mixing ratio with the set maximum mixing ratio, and an amplifier 2.
7, and is configured to control the pressure regulating valve 5 so that the mixing ratio is equal to or less than the maximum mixing ratio. 28
is an auto-selector circuit that selects the priority order for controlling the pressure control valve 5, and is configured to normally give priority to control based on the secondary wind speed _V2 , and to give priority to control based on the maximum mixing ratio only when there is interference with the maximum mixing ratio. has been done.

In the above configuration, when conveying the improved material by air, the instantaneous discharge amount, the minimum secondary wind speed, and the maximum mixing ratio are first set by the setting devices 15, 20, and 25. When the conveyance starts, the discharge of the improved material is detected by the load cell 12 supporting the improved material tank 1, and after adding the outputs of each load cell in the adder 13, the output is sent to the instantaneous discharge amount calculator 14, and the output is sent to the instantaneous discharge amount calculator 14. Calculate the instantaneous discharge amount of improved material to be discharged. This instantaneous discharge amount is then compared with the instantaneous discharge amount set value by the deviation calculator 16, and the variable speed motor 3 is controlled so that the former matches the latter. On the other hand, the primary pressure transmitter 2
9 is the primary pressure P ₁ , air flow transmitter 7 is the air flow rate
_Q1 , the secondary pressure transmitter 9 detects the secondary pressure _P2 , and based on these, the secondary wind speed calculator 19
calculates the secondary wind speed V ₂ , and the secondary wind speed
Find air weight W ₂ from V ₂ and secondary pressure P ₂ . Then, the deviation calculator 21 compares the secondary wind speed V ₂ with the minimum secondary wind speed, and controls the pressure regulating valve 5 via the autoselector circuit 28 so that the two coincide. Of course, this is true when the mixture ratio calculated by the mixture ratio calculator 24 is below the maximum mixture ratio, and when the mixture ratio becomes larger than the maximum mixture ratio, the deviation calculation unit 2
A signal from 6 is sent to the pressure regulating valve 5 via the autoselector circuit 28, which operates the pressure regulating valve 5 to control the mixture ratio to a low level.
By combining the three control methods of discharge amount control, secondary wind speed control, and mixture ratio control in this way, it is possible to control the instantaneous discharge amount to a constant level no matter how the pressure at the end of conveyance changes. Even though the pneumatic conveying type supply device is applied to a soft ground improvement machine, it is possible to reduce variations in the strength of the ground after improvement.

According to the first aspect of the invention, the discharge amount control means calculates the instantaneous discharge amount of the improved material conveyed from the improved material tank to the agitator, and controls the feeder to match the instantaneous discharge amount with the instantaneous discharge amount setting value. Therefore, even if there is a pressure change at the end of conveyance, it is possible to control the instantaneous discharge amount of the improved material to a constant value according to the set value, and it is possible to reduce the variation in the improved strength, and also to clogging of the improved material can be prevented. Also, calculate the secondary wind speed in the hose from the feeder to the agitator, and set this to a minimum of 2.
Since it is equipped with a secondary wind speed control means that controls the pressure regulating valve on the primary side to match the secondary wind speed setting value, it is possible to automatically supply improved material, and the secondary wind speed can be adjusted to the minimum secondary wind speed. It is possible to control the amount of air to the minimum required level, thereby downsizing the compressor and achieving significant energy savings.

Furthermore, according to the second invention, the discharge amount control means;
In addition to the secondary air speed control means, it is equipped with a mixture ratio control means that calculates the mixture ratio of the improving material and air and controls the pressure regulating valve to keep it below the set maximum mixture ratio. The flow state of the mixed flow of the improvement material and air becomes constant, and the supply of the improvement material into the soil becomes stable. Therefore, the quality of the improved column is improved, and at the same time, clogging of the improved material in the hose can be reliably prevented, and construction efficiency is significantly improved.
Furthermore, operator fatigue can be reduced.

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Improvement material tank, 2... Feeder, 4... Hose, 5... Pressure control valve, 11... Discharge amount control means, 1
4... Instantaneous discharge amount calculator, 18... Secondary wind speed controller, 19... Secondary wind speed calculator, 23... Mixing ratio controller, 24... Mixing ratio calculator.

Claims (1)

[Scope of Claims] 1. In a pneumatic improvement material supply device of a soft ground improvement machine, in which the improvement material in the improvement material tank is conveyed to the agitator by compressed air via a feeder, the improvement material is stirred from the improvement material tank. A discharge amount control means that calculates the instantaneous discharge amount of improved material conveyed to the machine and controls the feeder to match the instantaneous discharge amount setting value, and calculates the secondary wind speed in the hose from the feeder to the agitator. and secondary wind speed control means for controlling a pressure regulating valve on the primary side so as to match this to a minimum secondary wind speed set value. control device. 2. In a pneumatic improvement material supply device for a soft ground improvement machine, in which the improvement material in the improvement material tank is conveyed to the agitator by compressed air via a feeder, the improvement material is transported from the improvement material tank to the agitator. A discharge rate control means that calculates the instantaneous discharge rate of material and controls the feeder to match the instantaneous discharge rate set value, and a secondary wind speed in the hose from the feeder to the agitator, and calculates the secondary wind speed in the hose from the feeder to the agitator, and adjusts the rate to a minimum of 2. The secondary wind speed control means controls the pressure regulating valve on the primary side to match the set value of the secondary wind speed, and the mixing ratio of the improved material and air is calculated to keep it below the set maximum mixing ratio. A control device for a pneumatic improvement material supply device in a soft ground improvement machine, comprising a mixture ratio control means for controlling the pressure regulating valve.