JP6716275B2 - Fluid viscosity measuring device - Google Patents

Description

The present invention relates to an apparatus for measuring the viscosity of a fluid, and particularly to calculate the viscosity from the flow resistance of the fluid.

Conventionally, as a measuring instrument for measuring the viscosity of a fluid, there are a single cylinder type rotary viscometer (spindle type) and a conical plate type rotary viscometer (cone/plate type).

The applicant could not find any prior art document related to the present invention.

In the above-mentioned conventional measuring instrument, the viscosity can be obtained from the constant of proportionality based on the characteristic that the shear force changes in proportion to the shear rate of a normal Newtonian fluid. However, in a non-Newtonian fluid such as grease, since the relationship between the shear rate and the shear force is non-linear, it is not possible to accurately measure the viscosity with a conventional measuring instrument. In particular, it is necessary to grasp the viscosity of the fluid when designing a hydraulic damping device that uses the fluid as hydraulic oil.
Therefore, an object of the present invention is to provide a viscous fluid viscosity measuring device capable of accurately measuring the viscosity of a non-Newtonian fluid and evaluating the compatibility of the fluid with the hydraulic vibration damping device.

バイパス管１３は孔径の異なる複数のものから測定対象の流体に応じて選択するようにシリンダ９に着脱可能に構成する。 In order to solve the above-mentioned problems, in the present invention, a vibrating machine for applying vibration on a trial basis, a main body 4 that generates flow resistance of a fluid to be measured against this vibration, and a resistance force of the main body 4 are measured. The viscosity of the fluid is calculated from the load meter 3, the speed meter 5 for measuring the speed of vibration of the vibrator, the resistance force measured by the load meter 3, the speed measured by the speed meter 5, and the density of the fluid. And a computing device 6 for computing. The main body 4 has a cylinder 9 having one end connected to one of the load meter 3 and the actuator 2 of the vibration exciter, and one end of which is filled with a fluid to be measured, and the other end of the load meter 3 or the actuator 2 of the vibration exciter. And a piston rod 10 that is inserted into and out of the cylinder 9 and is fixed to the piston rod 10 to divide the inside of the cylinder 9 into first and second pressure chambers 14 and 15 and Flowable in accordance with the movement of the piston 11 that is movable in the direction and the first and second pressure chambers 14 and 15 that are filled with fluid and that communicate with the first and second pressure chambers 14 and 15 due to the vibration input by the vibration exciter. And a bypass pipe 13 for providing
The arithmetic unit 6 calculates the viscosity of the fluid by the following mathematical formula.

The bypass pipe 13 is attachable to and detachable from the cylinder 9 so as to select from a plurality of bypass pipes having different hole diameters according to the fluid to be measured.

The present invention has an effect that the viscosity of a non-Newtonian fluid can be accurately measured and the suitability of the fluid for the hydraulic vibration damping device can be accurately evaluated.

It is a schematic block diagram of the viscosity measuring apparatus which concerns on this invention. It is sectional drawing of the main body of the viscosity measuring apparatus of FIG. It is an expanded sectional view of a bypass pipe. It is an expanded sectional view of an orifice unit. It is an expanded sectional view of a connecting pipe. It is a flowchart which shows the calibration process of a viscosity measuring apparatus. It is a flowchart which shows the calculation process of viscosity.

An embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, the viscosity measuring device is fixed to a substantially rectangular frame body 1 which is long in the front-rear direction, an actuator 2 of a vibrator that penetrates one end of the frame body 1, and the other end inside the frame body 1. The relative speed of the load meter 3 and the main body 4 of which one end is connected to the actuator 2 of the vibrator and the other end is connected to the load meter 3 in the frame 1 and the main body 4 which expands and contracts by the operation of the actuator 2 It is provided with a speedometer 5 for measurement and a computer 6 which is an arithmetic unit for receiving data from the load meter 3 and the displacement meter 5 and performing a predetermined arithmetic processing.
It should be noted that the speedometer 5 is replaced by a displacement meter, and the relative displacement between the actuator 2 and the main body 4 is measured, and then differential processing is performed in the computer 6 using a sampling frequency or the like to substantially obtain speed data. May be

As shown in FIG. 2, the main body 4 is connected to the load meter 3 via a connecting portion 7, and a cylinder 9 is connected to the actuator 2 via a connecting portion 8 and is inserted into the cylinder 9 so as to freely move in and out in the axial direction. Piston rod 10, a piston 11 fixed on the piston rod 10, an accumulator 12 communicating with the pressure chambers 14 and 15 partitioned by the piston 11 in the cylinder 9, and a bypass also communicating with the pressure chambers 14 and 15. And a tube 13.

As shown in FIG. 2, the accumulator 12 adjusts the excess or deficiency of the fluid to be measured, which is filled in the cylinder 9 and the bypass pipe 13, due to a temperature change or the like. The accumulator 12 includes a pressurizing spring 12a and a piston 12b. A check valve 16 is provided between the accumulator 12 and the cylinder 9. This check valve 16 is always open by a spring, but when the pressure of the pressure chamber 14 (15) increases due to the vibration of the vibration exciter, it is closed to allow the fluid to flow into the bypass pipe 13, and the accumulator 12 The pressure applied keeps the pressure inside the cylinder 9 and the bypass pipe 13 constant.

As shown in FIG. 2, the bypass pipe 13 is passed between a pair of connection blocks 17 that are connected to both end lids 9 a and 9 b of the cylinder 9. As shown in FIG. 3, the bypass pipe 13 is adjacent to the flanges 18 at both ends, which are respectively coupled to the connection blocks 17 on the left and right sides, and a plurality of orifice units 19 arranged in the longitudinal direction between the flanges 18 on the left and right sides. It is composed of a connecting pipe 20 for connecting the orifice unit 19. Fluid passages pass through the connection block 17, the flange 18, and the end lids 9a and 9b, respectively, and communicate with the pressure chambers 14 and 15. The bypass pipe 13 can be attached to and detached from the cylinder 9 by fastening the flanges 18 on both the left and right sides to each other by tightening them with a turnbuckle 21. As shown in FIG. 4, the orifice unit 19 has a substantially columnar shape, and an orifice 19 a that generates flow resistance due to the viscosity of the fluid penetrates the central axis of the orifice unit 19 and communicates with the flow path of the flange 18. The connecting pipe 20 fits and connects the adjacent orifice units 19 and 19 around their abutting ends. At the center of the connecting pipe 20 in the axial direction, a ring piece 20a having a through hole 20b for contacting the end faces of the orifice unit 19 on both sides and communicating the orifice 19a is provided. In the orifice unit 19, a plurality of orifices 19a having different diameters are prepared in advance and replaced according to the test conditions, so that it is possible to test under various conditions suitable for the fluid to be measured together with the input speed of the vibrator.

In this viscosity measuring apparatus, the main body 4 is assembled to the frame body 1 together with the vibration exciter, the load meter 3 and the speedometer 5, and when vibration of the vibration exciter is applied via the actuator 2, the piston rod 10 is moved into the cylinder 9. Pushed in or pulled out. When the piston 11 moves in the cylinder 9 accordingly, the volumes of the pressure chambers 14 and 15 change, and the fluid inside the pressure chambers 14 and 15 flows. For example, when the piston 11 moves to the left in FIG. 2, the fluid is pushed out of the pressure chamber 14 by the piston 11, flows through the bypass pipe 13, and moves to the pressure chamber 15. At this time, the orifice 19a of the bypass pipe 13 restricts the flow of the fluid to generate flow resistance, and thus a resistance force against vibration is generated.

In this viscosity measuring device, since the resistance force against vibration is measured and the viscosity of the fluid is calculated backward, a calibration step is performed in which the characteristic that is the determining factor of the resistance force is acquired in advance. In this calibration step, a Newtonian fluid such as water or oil having a known viscosity/density is used to measure the resistance force generated by the viscosity measuring device, and the correlation between the viscosity/density and the resistance force is obtained. This calibration process is performed by the arithmetic processing of the computer 6 according to the procedure shown in FIG. 6 using the mathematical expressions and symbols in Tables 1 and 2 below. First, the diameter of the flow path (orifice 19a) of the bypass pipe 13 that is the source of the resistance force and the input speed measured by the speedometer 5 with respect to the vibration of the vibrator are set as test conditions that can be changed. And the viscosity/density of the fluid, the Reynolds (Re) number of the fluid flowing in the bypass pipe 13 is calculated according to the equation (6) in Table 1 (steps S1 to S4). The Re number is a reference for confirming whether the fluid flow in the bypass pipe 13 is in a turbulent state accompanied by vortices or in a laminar laminar flow state. When the Re number exceeds 2000, the input speed is appropriately changed by changing the vibration of the vibration exciter, which is a test condition, to obtain a laminar flow state of 2000 or less. From the viscosity/density of the fluid, the flow path diameter of the bypass pipe 13, and the input velocity, the resistance force F1 of the fluid in the bypass pipe 13 in the laminar flow state in the run-up section according to the equations (7) and (8) in Table 1 and The viscous drag force F2 generated by the viscosity of the fluid in a flow with a parabolic flow velocity distribution, which is a fully developed flow, is calculated (step S6). Next, among the resistance forces generated in the flow path of the bypass pipe 13, the in-pipe dynamic pressure resistance force F31 and the pipe outlet dynamic pressure resistance force F32, which are the resistance forces of the fluid generated at the position where the cross-sectional area of the flow path increases. It is calculated according to equations (9) and (10) (step S7). The in-pipe dynamic pressure resistance force is multiplied by the correction coefficient α to obtain the in-pipe dynamic pressure resistance force F31 for evaluation (steps S8 and S9). The other resistance force Fetc generated in the flow path of the bypass pipe 13 and the sliding resistance Fs of the seal material used to seal the fluid in the device are added as correction values, and the resistance force Fev= to the input vibration F1+F2+F31+F32+Fs+Fetc is calculated (step S11). An error between the measured value Fall and the calculated value Fev of the resistance force by the load cell 3=(measured value−calculated value)/measured value×100 is obtained (steps S5 and S12). If this error exceeds 10%, the correction coefficient α of the in-pipe dynamic pressure resistance force F31, the other resistance force Fetc, and the sliding resistance Fs of the seal material are reviewed and appropriately changed. When the error is within 10%, the correction coefficient of the in-pipe dynamic pressure resistance force F31 corresponding to the flow path diameter/input speed of the bypass pipe 13, other resistance force Fetc, and the sliding resistance Fs of the seal material are determined. ..

The calculation method of the viscosity of the fluid by the viscosity measuring device is performed by the arithmetic processing by the computer 6 according to the procedure as shown in FIG. First, the flow path diameter of the bypass pipe 13 and the fluid density are used as the measurement conditions, and the measured resistance force and the input speed of the vibration exciter, and the in-pipe dynamic pressure resistance force determined according to the measurement conditions by the previous calibration process. From the correction coefficient α of F31, the other resistance force Fetc, and the sliding resistance Fs of the seal material, the shear rate γ from the pipe wall surface of the fluid flowing in the flow passage of the bypass pipe 13 to the pipe central axis is calculated by the formula (3). (Steps S14 to S17). Furthermore, from the flow path diameter of the bypass pipe 13, the input velocity, and the density of the fluid, the resistance force F1 of the fluid in the laminar flow state, the dynamic pressure resistance force F31 in the pipe, and the equation (7), (9), and (10) The pipe outlet dynamic pressure resistance force F32 is calculated. According to the equation (1), from the resistance force Fall, the resistance force F1 of the fluid in the laminar flow state, the pipe dynamic pressure resistance force F31, the pipe outlet dynamic pressure resistance force F32, the other resistance force Fetc and the sliding resistance Fs of the sealing material. And the viscous resistance force F2 is calculated (step S19). From this viscous resistance force F2, the apparent viscosity of the fluid with respect to the shear rate of the fluid flowing in the flow path of the bypass pipe 13 is calculated by the equation (2) (step S20).

Thus, the resistance force of the fluid generated in the flow path is calculated by the formula shown in Table 1, and the viscosity of the hydraulic oil necessary for the damper design is calculated by back-calculating from the resistance force confirmed by the vibration exciter. it can.
Depending on the confirmation, the resistance force generated at the corners of the flow path, the part where the cross-sectional area is reduced, and the flow path connection part where the flow path is short is omitted as a small value or is corrected using a correction coefficient or the like. ..

1 Frame 2 Actuator 3 Load meter 4 Main body 5 Speedometer 6 Computer (calculator)
7 connection part 8 connection part 9 cylinder 9a end cover 9b end cover 10 piston rod 11 piston 12 accumulator 12a pressurizing spring 12b pressurizing piston 13 bypass pipe 14 pressure chamber 15 pressure chamber 16 check valve 17 connection block 18 flange 19 orifice unit 19a Orifice 20 Connection pipe 20b Through hole 20a Ring piece 21 Turnbuckle

Claims (3)

A shaker that applies vibration on a trial basis, a body that generates flow resistance of the fluid to be measured against this vibration, a load meter that measures the resistance force of this body, and the speed of vibration of the shaker A speedometer for measuring, a resistance force measured by the load meter, a speed measured by the speedometer, and a calculation device for calculating the viscosity of the fluid from the density of the fluid,
The main body has a cylinder, one end of which is connected to one of the load cell or the actuator of the vibration exciter, and the inside of which is filled with the fluid;
A piston rod, one end of which is connected to the other of the load cell or the actuator of the vibration exciter, and which is inserted into the cylinder so that the piston rod can freely move in and out,
A piston that is fixed to the piston rod, divides the inside of the cylinder into first and second pressure chambers, and is movable in the cylinder in the axial direction;
A bypass pipe that is filled with fluid and communicates with the first and second pressure chambers, and that imparts flow resistance to the fluid that flows as the piston reciprocates due to the vibration input by the vibration exciter. Then
A viscous fluid viscosity measuring device capable of measuring a viscosity change due to continuous shearing due to flow resistance against bidirectional flow of fluid in the bypass pipe . The viscous fluid viscosity measuring apparatus according to claim 1, wherein the arithmetic unit calculates the viscosity of the fluid by the following mathematical formula.

However, μ: viscosity, F ₂ : viscous resistance force, F ₁ : fluid resistance force, A _p : effective pressure receiving area, V: piston speed, L: flow passage length, a: flow passage cross-sectional area , k: bypass Flow paths in the pipe, n: Number of flow paths in the bypass pipe . The viscosity measuring apparatus for viscous fluid according to claim 1 or 2, wherein the bypass pipe is detachably attached to the cylinder by selecting from a plurality of bypass pipes having different hole diameters according to a fluid to be measured.

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