SU1345095A1 - Arrangement for loading ground-testing device - Google Patents

Abstract

The invention relates to the field of construction, in particular to the study of the physicomechanical properties of soils. The aim of the invention is to simplify the design of the device. This is achieved by placing inside the tank 7 a heater 9 and a pressure sensor 10 rigidly fixed on the table 1. The latter is connected to the inverting input of a comparator, the load of which is the key. A heater 9 is connected to the power supply in series with the key contacts. A potentiometer slider is connected to the non-inverting comparator input, the position of which determines the level of the reference voltage corresponding to the required load. 2 Il. Q SS (L with SP has co

Description

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The invention relates to the construction, in particular to the study of the physical and mechanical properties of soils. The aim of the invention is to simplify the design of the device.

FIG. 1 shows the proposed device, a general view; in fig. 2 is an electrical connection diagram of the device.

The device contains a table 1, on which an odometer 2 is installed with a primer 3 placed in it. Frame 4 is connected to punch 5 and comes in contact with the loose end of the bellows 6. The opposite end of the bellows is fixed on the tank 7 and is rigidly connected to the table 1. The bellows cavities and the reservoir communicating through the opening 8 is sealed and filled with a liquid, such as spun or transformer oil. A heater 9 and a pressure sensor 10, for example an MM358 oil pressure sensor from a GAZ-24, are placed inside the tank. Then it is connected to the inverting input of the comparator 11, the load of which is the key 12, which conducts the current in the absence of a control signal (for example, a relay with normally closed contacts). A heater 9 is connected to the power supply in series with the key contacts. A potentiometer slider 13 is connected to the non-inverting comparator input, the position of which determines the level of the reference voltage corresponding to the required load. Resistances 14 and 15

together with sensor 10 with potentiometer 40, since its sign is reversed (in this case, positive), diode 17 is unlocked, relay 16 is triggered, and its contacts open the heater circuit 9. At the slightest decrease in pressure, in the tank (by moving the die due to an increase in the precipitation of the soil or the cooling of the liquid), the voltage on the sensor 10 increases, the relay contacts are closed again, turning on

13 respectively form a voltage divider. Relay 16 and diode 17 are part of switch 12. Power supply 18 produces voltages for supplying a comparator and a heater.

The device works as follows.

When the device is turned on, the heating and expansion of the fluid in reservoir 7 begins. Excess fluid is displaced into the bellows 6 through the opening 8, causing the bellows to stretch. The pressure from the bellows on the frame 4 is transmitted by means of the stamp 5 to the ground 3. In connection with the resistance of the soil to the compression, the pressure of the fluid increases, the membrane of the sensor 10 bends (see the lower left part of the drawing), causing the slider to move

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50

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heater, etc. In this way, the punch pressure is stabilized at a predetermined level. Since the above comparator on the operational amplifier responds to signals in the order of hundredths of a millivolt, the tracking accuracy of such a system reaches one-tenth of a percent of the set load value

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rheochord included in the sensor. The pitch on the inverter input of the comparator decreases. The level of the reference voltage at the non-inverting input of the comparator can be set by the potentiometer slider 13, equipped with a limb with digitization in: load units. Instead of a potentiometer, it is possible to use a switch of constant resistance in a voltage divider circuit - for a fixed, stepwise change in load. At the moment of switching on the device, the positive voltage at the inverting input of the comparator is determined by the ratio of the nominal resistance 14 and the total initial resistance of the sensor 10. The ratio is such that this voltage is certainly greater than the reference. Therefore, the voltage at the comparator output has a negative 5 polarity, the diode 17 does not pass current through the winding of the relay 16, and the heater circuit remains closed. An increase in pressure in reservoir 7 (as a result of heating and expansion of the fluid) determines a gradual decrease in the resistance of the sensor 10 and the voltage at the inverting input of the comparator. But the state of the circuit does not change until this voltage is comparable to the reference. At this moment (corresponding to the achievement of the set load), the voltage at the comparator output abruptly (from –Ec to + E |).

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thirty

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0 because its sign is reversed (in this case, positive), diode 17 is unlocked, relay 16 is triggered, and its contacts open the heater circuit 9. At the slightest decrease in pressure, in the tank (due to movement of the punch due to an increase in precipitation or liquid cooling) the voltage on the sensor 10 increases, the relay contacts are closed again, turning on

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five

heater, etc. In this way, the punch pressure is stabilized at a predetermined level. Since the above comparator on the operational amplifier responds to signals in the order of hundredths of a millivolt, the tracking accuracy of such a system reaches one-tenth of a percent of the set load value

and is mainly determined by the resolution of pressure sensor i

Claims (1)

Invention Formula Loading device for soil testing instruments, including a table, a stamp, a loading device associated with it in the form of a reservoir and bellows interconnected, fixed by one torus It is stationary relative to the table, and a pressure sensor, characterized in that, in order to simplify the design, the loading device is equipped with a heater, a power source and a comparator with a key at the outlet, while the pressure sensor is mounted in the tank and connected to one of the comparator inputs, and the heater included in the power supply circuit in series with the key.  -ZIOS Editor A.Makovska Compiled by B.Vrachev Tehred M.Hodanich Order 4912/42 Circulation 776 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 Fig2 Proofreader A.T. sko