JP6202333B2 - Rotational viscometer - Google Patents

Description

  The present invention relates to a rotational viscometer, and more particularly to an outer cylinder rotating type coaxial double cylindrical rotational viscometer.

The rotational viscometer is roughly divided into a cone-plate type and a coaxial double cylindrical type depending on the shape of the portion in contact with the sample. Both of them can be used for measurement of a sample whose shear rate is dependent on the shear rate because the sample flow rate (deformation) can be measured regardless of the location of the sample.
Further, the rotational viscometer has a function of transmitting rotation to the sample portion and measuring response torque, or transmitting torque and rotating it and measuring the rotation speed. Since it is necessary to control the temperature of the sample portion, the sample portion is taken out to a position separated by a rotating shaft and is operated or measured.
A coaxial double-cylinder rotational viscometer widely used as a rotational viscometer (see Patent Documents 1 and 2, etc.) holds a sample between an outer cylinder and an inner cylinder whose central axes coincide with each other, and performs many measurements. The device is configured so that either one of them rotates and torque is measured or generated on the inner cylinder side. The theory of measurement is based on an infinitely long double cylinder, but it is not realistic. Therefore, in practice, the influence of the end face is evaluated and corrected.

JP 2005-49214 A JP 2009-63505 A

The coaxial double cylinder type rotational viscometer needs to correct the influence of the end face, and the fluctuation of the end face correction amount becomes a problem particularly in the measurement of a sample whose viscosity is highly dependent on the shear rate. Various end face corrections have been proposed in the past, and the present applicants have previously proposed Patent Document 2 regarding the correction amount on the lower surface of the inner cylinder. However, it has been difficult to obtain an accurate correction amount for the end face correction amount on the upper surface of the inner cylinder.
Moreover, in order to control the temperature of the sample part, the coaxial double cylindrical rotational viscometer has been controlled by putting the outer cylinder in a liquid thermostat. However, since heat transfer occurs along the inner cylinder shaft at the upper part of the inner cylinder, there is a limit to making the temperature control of the sample highly accurate.
In addition, the coaxial double cylinder type rotational viscometer is separated from the position of the inner cylinder that is the measurement unit of the shaft holding position, and is configured to be cantilevered, so during an operation such as replacing the inner cylinder, There is a risk of damaging the bearing.
Therefore, an object of the present invention is to provide an outer cylinder rotation type coaxial double cylindrical rotational viscometer that solves the above three problems.

  In order to solve the above-described problems, the present invention provides an outer cylinder rotation type coaxial double cylinder type rotational viscometer, in which a fixed guard shaft is installed outside the inner cylinder shaft, and a plurality of functions are provided on the fixed guard shaft. At the same time, or by providing the fixed guard shaft with a function selected as necessary, the above three problems are solved.

That is, the present invention relates to an outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper part of the inner cylinder and supported by a bearing, and an inner cylinder shaft. A torque detection mechanism provided, and rotating the outer cylinder causes the sample fluid filled between the outer cylinder and the inner cylinder to rotate and flow in a laminar flow state, and the torque acting on the inner cylinder is caused by the torque detection mechanism. An outer cylinder rotation type coaxial double cylinder type rotational viscometer for detecting and measuring viscosity, provided with a fixed guard shaft surrounding the outer side of the inner cylinder shaft, An inner cylinder shaft guard that suppresses excessive displacement in the direction is provided.
Further, the present invention provides an outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper part of the inner cylinder and supported by a bearing, and an inner cylinder shaft. A torque detection mechanism provided, and rotating the outer cylinder causes the sample fluid filled between the outer cylinder and the inner cylinder to rotate and flow in a laminar flow state, and the torque acting on the inner cylinder is caused by the torque detection mechanism. An outer cylinder rotation type coaxial double cylinder type rotational viscometer for detecting and measuring the viscosity, provided with a fixed guard shaft surrounding the outer side of the inner cylinder shaft, the fixed guard shaft having the same radius as the inner cylinder The inner cylinder upper surface guard cylinder is provided at a position where the inner cylinder peripheral surface extends upward with a slight gap therebetween.
Further, the present invention provides an outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper part of the inner cylinder and supported by a bearing, and an inner cylinder shaft. A torque detection mechanism provided, and rotating the outer cylinder causes the sample fluid filled between the outer cylinder and the inner cylinder to rotate and flow in a laminar flow state, and the torque acting on the inner cylinder is caused by the torque detection mechanism. An outer cylinder rotation type coaxial double cylinder type rotational viscometer for detecting and measuring the viscosity, comprising a thermostatic bath for holding the outer cylinder and holding the temperature of the sample fluid at a predetermined temperature. A fixed guard shaft surrounding the outside is provided, and a temperature adjusting member is provided on the fixed guard shaft.
Further, the present invention provides an outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper part of the inner cylinder and supported by a bearing, and an inner cylinder shaft. A torque detection mechanism provided, and rotating the outer cylinder causes the sample fluid filled between the outer cylinder and the inner cylinder to rotate and flow in a laminar flow state, and the torque acting on the inner cylinder is caused by the torque detection mechanism. An outer cylinder rotation type coaxial double cylinder type rotational viscometer for detecting and measuring the viscosity, comprising a thermostatic bath for holding the outer cylinder and holding the temperature of the sample fluid at a predetermined temperature. A fixed guard shaft is provided to surround the outside, a temperature adjusting member is fixed to the fixed guard shaft, and an inner cylinder upper surface guard cylinder having the same radius as the inner cylinder is sandwiched between the fixed guard shaft with a slight gap. The inner cylinder peripheral surface is provided at a position extending upward.
Further, the present invention provides the outer cylinder rotation type coaxial double cylindrical rotational viscometer, wherein the fixed guard shaft is provided with an inner cylinder shaft guard that suppresses excessive lateral displacement of the inner cylinder shaft. It is characterized by.

According to the inner cylinder shaft guard provided on the fixed guard shaft of the present invention, the inner cylinder shaft is designed at a distance from the narrow inner cylinder shaft so that even if the inner cylinder shaft is displaced due to excessive force, the bearing is prevented from being damaged. Therefore, when the inner cylinder shaft is about to be largely decentered, it strikes the inner cylinder shaft guard, and no further eccentricity occurs, and damage to the bearing can be prevented.
According to the inner cylinder upper surface guard cylinder provided on the fixed guard shaft of the present invention, end face correction can be made unnecessary for the upper surface of the inner cylinder.
According to the temperature adjusting member provided on the fixed guard shaft of the present invention, if the temperature of the fixed guard shaft is controlled to be the same as the temperature of the thermostatic bath or the inner cylinder, the upper part of the outer cylinder or the inner cylinder The temperature gradient is eliminated, and as a result, the controllability of the sample temperature is improved.
Further, the inner cylinder shaft guard, the inner cylinder upper surface guard cylinder, and the temperature adjusting member of the present invention can be provided on the fixed shaft guard alone or in combination of two or more.

FIG. 1 shows an embodiment of a coaxial double cylindrical rotational viscometer of the outer cylinder rotation type of the present invention. FIG. 2 is a diagram for explaining the inner cylinder upper surface guard cylinder of the present invention, and the left figure shows a conventional outer cylinder rotation type coaxial double cylindrical rotational viscometer (fixed guard shaft / inner cylinder upper surface guard cylinder). In the case of (No), the right figure shows the case of a coaxial double cylinder type rotational viscometer of the outer cylinder rotation type having the fixed guard shaft and inner cylinder upper surface guard cylinder of the present invention.

The fixed guard shaft of the present invention is a hollow shaft that is disposed in a state of surrounding the periphery of a shaft portion (inner tube shaft) for supporting the inner tube from above. The present invention assumes an outer cylinder rotation type coaxial double cylinder type rotational viscometer, and the inner cylinder and the inner cylinder shaft are suspended so that unnecessary torque does not act for torque measurement. In order to increase the torque measurement sensitivity of the inner cylinder, the inner cylinder and the inner cylinder shaft require delicate bearings and have a structure that is relatively fragile. On the other hand, the fixed guard shaft is not in direct contact with the inner cylinder and the inner cylinder shaft, and is a highly rigid structure. By disposing a highly rigid structure outside the inner cylinder shaft, the following three functions can be provided.
(1) The principle of the outer cylinder rotation type coaxial double cylinder type rotational viscometer prescribes an infinitely long double cylinder, but a part of the long cylinder is used as the cylinder of the measurement part, and both ends are very If the structure is such that it is mechanically separated at small intervals and geometrically forms one cylinder, the cylinder of the measurement part can satisfy the principle of a coaxial double-cylinder rotational viscometer. , End face correction becomes unnecessary. In the present invention, if the fixed guard shaft is a cylinder having a radius and an axial center coinciding with the inner cylinder, and sufficiently close to the inner cylinder, the measurement principle for the upper surface of the inner cylinder is satisfied, and end face correction is not required. Can do.
(2) Since the outer cylinder rotation type coaxial double cylinder type rotational viscometer can put the outer cylinder in a liquid thermostat, the temperature control performance is superior to the conical plate type rotational viscometer. However, since the upper part of the inner cylinder cannot be made thinner, if there is a difference between the room temperature and the temperature of the thermostatic chamber, there is a temperature difference between the inner cylinder and the sample due to heat transfer from the upper part of the outer cylinder and the inner cylinder shaft. End up. On the other hand, the fixed guard shaft of the present invention has a structure that encloses the inner cylinder shaft, and is located at the upper part of the outer cylinder, so that the temperature of the fixed guard shaft is the same as the temperature of the thermostatic bath or the inner cylinder. If this is controlled, the temperature gradient between the upper part of the outer cylinder or the inner cylinder is eliminated, and as a result, the controllability of the sample temperature is improved.
(3) When a lateral force is applied to the inner cylinder shaft, the inner cylinder shaft supported by the delicate bearing is eccentric from the shaft center due to deformation of the bearing. If the eccentricity exceeds the allowable range, the bearing may be damaged. On the other hand, if the fixed guard shaft is arranged with a sufficiently small distance from the inner cylinder shaft, it will hit the inner cylinder shaft guard when the inner cylinder shaft is eccentric and no further eccentricity will occur. Can prevent damage.
The above three functions can be achieved individually, but any two functions or all three functions can be simultaneously incorporated into one fixed guard shaft.

FIG. 1 shows an embodiment of a coaxial double-cylinder rotational viscometer of the outer cylinder rotation type having a fixed guard shaft according to the present invention. This is an example of incorporation into two fixed guard shafts.
As shown in FIG. 1, a double cylinder is placed in a thermostatic chamber (d) placed on the lifting device (i), and is held coaxially with the double cylinder outer cylinder (j). A measurement sample enters between the inner cylinder (c), the inner cylinder (c) is fixed to the lower end of the inner cylinder shaft, and a torque detection mechanism (a, e, f) for detecting torque is provided on the inner cylinder shaft side. And has a rotation mechanism (g, h) for rotating the outer cylinder (j). The inner cylinder side is supported by a bearing (b) having a small rotational resistance, such as an air bearing, in order to detect torque. In the example shown in the figure, the detection mechanism for detecting the torque by rotating the outer cylinder in a laminar flow and the torque corresponding to the viscosity of the sample acting on the inner cylinder is detected at the upper part of the inner cylinder shaft. Torque is detected by detecting the amount of rotational displacement from the reference position with the provided rotational position detector (e) and controlling the amount of current flowing through the torque applying means (a) so that the control means (f) always returns to the reference position. However, any detection mechanism may be used as long as the torque can be detected. As a rotation mechanism of the outer cylinder (j), a motor (g) and a gear transmission mechanism (h) However, the present invention is not limited to this.

Next, the point provided with the above-mentioned three functions that are the features of the present invention will be described below.
In this embodiment, first, in order to make torque measurement highly sensitive, in view of the fact that many bearings (b) are fragile, a fixed guard shaft (k) that can be directly fixed to a strong base plate (q) is installed. For example, the inner cylinder shaft guard (m) that suppresses the displacement exceeding the limit of the inner cylinder shaft can be installed. As shown in FIG. 1, the inner cylinder shaft guard (m) attached to the fixed guard shaft (k) has a narrow inner diameter so that the bearing can be restrained from being damaged even if the inner cylinder shaft is displaced by a force. Designed at a distance from the cylinder axis.
In this embodiment, in addition to this, a fixed shaft is formed so that the inner cylinder upper surface guard cylinder (n) having the same radius as the inner cylinder (c) extends upward with the circumferential surface of the inner cylinder (c) sandwiched by a slight gap. When installed on the guard (k), the flow of fluid on the upper surface of the inner cylinder can be eliminated, and the flow in accordance with the principle of the coaxial double cylinder can be realized on the upper surface of the inner cylinder. This makes it closer to the advantage of the conical flat plate type that the shear rate of the sample to be measured is more strictly determined without losing the characteristic that the sample can be accurately measured without strict amount of the sample, which is an advantage of the coaxial double cylinder. (In other words, even if the sample liquid level fluctuates due to the difference in the amount of the sample, the torque due to the flow of the sample fluid that acts on the upper surface of the inner cylinder can be cut off by the inner cylinder upper surface guard cylinder (n). Even if the surface moves up and down, the upper surface of the inner cylinder is not affected. As for the non-ideality of the lower end of the inner cylinder, for example, the conical shape described in Patent Document 2 is introduced so that the distance from the outer cylinder is proportional to the radius. Alternatively, as shown in FIG. By adopting a co-hemispherical shape, it is possible to reduce the influence of such non-ideality.
In this embodiment, when a temperature adjusting member (o) having a heat generating / absorbing action such as a heater or a Peltier element is installed at an appropriate place on the upper surface of the inner cylinder, and the temperature at that place is controlled, the inner cylinder shaft The temperature gradient from the position of the member to the upper surface of the inner cylinder can be reduced, and the temperature control performance of the inner cylinder can be improved. In addition, the heat exchanger (p) of FIG. 1 is installed by the necessity of releasing heat outside, when the temperature control member (o) is a Peltier element. The heat exchanger (p) and the temperature adjustment member (o) are transferred with heat by a heat pipe or the like. In addition, if a mechanism for exchanging heat with the outside using a heat pipe or the like is introduced as described above, the upper part of the inner cylinder shaft is close to the outside, that is, the environmental temperature of the apparatus. Thereby, the influence of the thermal expansion of the inner cylinder shaft or the influence of the heat of the measuring part inside the apparatus can be reduced. This mechanism is also possible by providing a fixed guard shaft (k).

FIG. 2 is a diagram for explaining the function of the inner cylinder upper surface guard cylinder (n). The left figure is a conventional outer cylinder rotation type coaxial double cylinder type rotational viscometer (fixed guard shaft / inner In the case of no cylinder upper surface guard cylinder), the right figure shows the case of the outer cylinder rotation type coaxial double cylinder type rotational viscometer having the fixed guard shaft and inner cylinder upper surface guard cylinder of the present invention.
In the conventional configuration shown in the left figure, when the outer cylinder (j) rotates around the rotation axis (t), the inner cylinder (c) The upper surface of the cylinder (c) and the lower surface of the inner cylinder (c) also receive torque due to the flow of the measurement sample fluid, and the total torque is detected by a torque detection mechanism (not shown) provided on the upper part of the inner cylinder shaft (s). Is done. The torque received on the upper and lower surfaces of the inner cylinder is an error factor in measuring the shear rate dependence of the viscosity, which is a feature of the coaxial double cylinder system, and is therefore preferably eliminated. For this reason, regarding the torque from the lower surface (see the arrow toward the lower surface), as illustrated in the lower part of the right figure, the distance between the bottom surface of the inner cylinder and the bottom surface of the outer cylinder is proportional to the radius from the central axis. By matching the distance between the cylinder side surface and the outer cylinder side surface, the error factor can be reduced (see Patent Document 2), or the inner cylinder bottom surface and the inner cylinder side surface are gently hemispherical as shown in FIG. It is possible to reduce the error factor better by connecting on the surface. However, the torque acting on the upper surface of the inner cylinder (see the arrow toward the upper surface) cannot be relaxed structurally with the conventional configuration. Therefore, for example, if the sample amount is not managed accurately, the sample liquid level fluctuates due to increase / decrease of the sample amount, and if the liquid level fluctuates, the magnitude of the torque acting on the upper surface of the inner cylinder also fluctuates, which causes measurement errors.
The right figure shows the configuration of the present invention, which is provided with an inner cylinder upper surface guard cylinder (n) at a position where the inner cylinder side surface extends upward, and is integrated with a fixed guard shaft (k) (not shown). It is fixed. Since the inner cylinder upper surface guard cylinder (n) blocks the flow of the sample rotating and rotating by the rotating outer cylinder (j), the flow of the sample on the upper surface of the inner cylinder can be eliminated, and the viscosity acting on the upper surface of the inner cylinder can be prevented. Torque, which becomes an error factor in measurement of speed dependence, can be structurally interrupted by the inner cylinder upper surface guard cylinder (n) (see the upper arrow).

In the above-described embodiment, all three of the inner cylinder shaft guard (m), the inner cylinder upper surface guard cylinder (n), and the temperature adjustment member (o) are fixed to the fixed guard shaft (k) surrounding the inner cylinder shaft. However, it goes without saying that the respective effects can also be obtained by fixing at least one of the inner cylinder shaft guard (m), the inner cylinder upper surface guard cylinder (n), and the temperature adjusting member (o).
The inner cylinder shaft guard (m), the inner cylinder upper surface guard cylinder (n), and the temperature adjustment member (o) have been described as being fixed to the fixed guard (k). You can also.

  In the above description, the rotational viscometer has been described, but it can also be used as a rheometer.

Claims (5)

An outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper portion of the inner cylinder and supported by a bearing, and a torque detection mechanism provided on the inner cylinder shaft And rotating the outer cylinder to rotate the sample fluid filled between the outer cylinder and the inner cylinder in a laminar flow state, and the torque acting on the inner cylinder is detected by the torque detection mechanism and the viscosity is measured. It is a coaxial double cylinder type rotational viscometer of outer cylinder rotation type,
A fixed guard shaft that surrounds the outer side of the inner cylinder shaft, and an inner cylinder shaft guard that suppresses excessive lateral displacement of the inner cylinder shaft is provided on the fixed guard shaft. A coaxial double cylinder type rotational viscometer. An outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper portion of the inner cylinder and supported by a bearing, and a torque detection mechanism provided on the inner cylinder shaft And rotating the outer cylinder to rotate the sample fluid filled between the outer cylinder and the inner cylinder in a laminar flow state, and the torque acting on the inner cylinder is detected by the torque detection mechanism and the viscosity is measured. It is a coaxial double cylinder type rotational viscometer of outer cylinder rotation type,
A fixed guard shaft that surrounds the outer side of the inner cylinder shaft is provided, and an inner cylinder upper surface guard cylinder having the same radius as the inner cylinder is extended to the fixed guard axis with a slight gap therebetween to extend the inner cylinder circumferential surface upward. An outer cylinder rotating type coaxial double cylindrical rotational viscometer characterized by being provided. An outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper portion of the inner cylinder and supported by a bearing, and a torque detection mechanism provided on the inner cylinder shaft And rotating the outer cylinder to rotate the sample fluid filled between the outer cylinder and the inner cylinder in a laminar flow state, and the torque acting on the inner cylinder is detected by the torque detection mechanism and the viscosity is measured. It is a coaxial double cylinder type rotational viscometer of outer cylinder rotation type,
A thermostatic chamber for holding the outer cylinder and holding the temperature of the sample fluid at a predetermined temperature;
An outer cylinder rotation type coaxial double cylindrical rotational viscometer characterized in that a fixed guard shaft surrounding the outer side of the inner cylinder shaft is provided, and a temperature adjusting member is provided on the fixed guard shaft. An outer cylinder and an inner cylinder having the same central axis, a rotation mechanism for rotating the outer cylinder, an inner cylinder shaft fixed to the upper portion of the inner cylinder and supported by a bearing, and a torque detection mechanism provided on the inner cylinder shaft And rotating the outer cylinder to rotate the sample fluid filled between the outer cylinder and the inner cylinder in a laminar flow state, and the torque acting on the inner cylinder is detected by the torque detection mechanism and the viscosity is measured. It is a coaxial double cylinder type rotational viscometer of outer cylinder rotation type,
A thermostatic chamber for holding the outer cylinder and holding the temperature of the sample fluid at a predetermined temperature;
A fixed guard shaft that surrounds the inner cylinder shaft is provided, a temperature adjustment member is provided on the fixed guard shaft, and an inner cylinder upper surface guard cylinder having the same radius as the inner cylinder is provided on the fixed guard shaft with a slight gap. An outer cylinder rotation type coaxial double cylinder type rotational viscometer, characterized in that it is provided at a position where the inner cylinder peripheral surface extends upward with the cylinder interposed therebetween.   5. The outer cylinder rotation type coaxial shaft according to claim 2, wherein an inner cylinder shaft guard that suppresses excessive lateral displacement of the inner cylinder shaft is provided on the fixed guard shaft. Heavy cylindrical rotational viscometer.

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