JPH0451780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotational viscometer used for measuring the viscosity of various liquids, pastes, gels, etc.

[Conventional technology]

Several types of viscometers have been known so far. For example, in a rotational viscometer that utilizes the relationship between motor torque and rotational speed, a rotating body 2 is immersed in a sample liquid 1 to be measured as shown in FIG. 4. As the motor 4, a small electric motor with drooping characteristics is used. The drooping characteristic is a characteristic in which the rotational speed decreases as the torque (load of the motor) increases, as shown in FIG. The motor 4, which has drooping characteristics, can determine the amount of change ΔT in the load torque by detecting the change Δω in its rotational speed.

Thus, since the rotating body 2 rotates while receiving a load torque corresponding to the viscosity of the sample liquid 1, the rotation speed increases or decreases according to the viscosity of the sample liquid 1. Therefore, by detecting the amount of change Δω in the rotational speed of the motor 4, the viscosity can be determined based on the change ΔT in the load torque.

According to such a rotary viscometer that is directly coupled to a motor, the characteristics of the motor 4 itself are used as a torque detection means, and since the motor 4 itself serves as both a driving part and a detection part, the rotational viscosity of other systems cannot be measured. Compared to a meter that requires a separate drive section and torque detection section, it has the advantage of being relatively simple in structure, less prone to failure, and having good response and reproducibility.

[Problem that the invention seeks to solve]

In this type of rotational viscometer, the accuracy of the rotational speed of the motor 4 is important, but since the controllability of the motor 4 is poor in the low-speed rotation region, there is a limit to lowering the rotational speed. Although it is possible to use a speed reducer to lower the rotation speed, it is not desirable to use a speed reducer because the friction of the gears etc. will have a negative effect on the measurement results.

Therefore, the rotating body 2 must be rotated at a relatively high speed. However, if the rotating body 2 rotates faster, turbulence is likely to occur in the sample liquid, which will adversely affect the measurement results. Therefore, the range in which the rotation speed can be set is narrow. Moreover, although the rotational speed of the rotating body 2 inevitably changes depending on the viscosity of the sample liquid 1, it is not preferable for the measurement conditions to change in this way.

[Means for solving problems]

The viscometer of the present invention has a rotating shaft to which a rotating body in contact with a sample liquid is connected, and has characteristics (such as drooping characteristics) in which the rotational speed ω ₁ of the rotating shaft changes in response to the magnitude of load torque. a first detection means for detecting an apparent rotational speed ω ₀ of the rotating body relative to the sample liquid; and a first detection means for detecting an apparent rotational speed ω ₀ of the rotating body to maintain a preset value. A second motor rotates the stator of the first motor at a rotational speed ω ₂ in the opposite direction to the rotational axis of the first motor, and a stator of the first motor rotates at a rotational speed ω ₂ or a second detection means for detecting the rotational speed ω ₂ of the rotor of the second motor;
and a display that displays a value related to the rotational speed ω ₂ detected by the detection means or a viscosity calculated based on the rotational speed ω ₂ . In addition,
The sample liquid is not limited to a liquid, and may be in the form of a paste or gel, for example.

[Effect]

In the above configuration, the rotating shaft to which the rotating body in contact with the sample liquid is connected is rotated by the first motor at a rotation speed of ω ₁ , but the first motor itself is rotated by the second motor. It is rotated at a rotation speed of ω ₂ in the opposite direction to the axis. Therefore, the apparent rotational speed ω ₀ of the rotating body relative to the sample liquid is |ω ₁ |−|ω ₂ |. This rotational speed ω ₀ is the first
is detected by the detection means.

Since the rotating body receives a load torque depending on the viscosity of the sump liquid, the rotation speed ω ₁ changes depending on the viscosity, that is, the load torque. Therefore, the second motor has the apparent rotational speed ω ₀ of the rotating body.
The rotation speed ω ₂ of the stator of the first motor is changed in accordance with the change in the rotation speed ω 1 so that the rotation speed ω ₂ is maintained at a preset constant value. This change in rotational speed ω ₂ is detected by the second detection means.

In this way, ω ₂ changes depending on the viscosity of the sample liquid. Since ω ₂ is a value related to the load torque that the rotating body receives, that is, the viscosity, based on this ω ₂ value and a constant determined in advance,
The viscosity of the sample liquid can be derived.

Example 1 A viscometer 10 according to an example of the present invention shown in FIG. 1 includes a first motor 11 and a second motor 12. The viscometer 10 shown in FIG. The first motor 11 is a DC motor with drooping characteristics, and has a stator 15 and a rotor 16, and the rotor 16 is provided with a rotating shaft 18. A rotating body 20 that contacts the sample liquid 1 is detachably connected to the rotating shaft 18 . Since this motor 11 has a drooping characteristic, the sample liquid 1
The rotational speed ω ₁ of the rotating shaft 18 changes depending on the magnitude of the load torque received from the rotating shaft 18 .

Further, the stator 15 of the first motor 11 is supported by a housing (not shown) so as to be rotatable around an axis around a rotational axis 18. This stator 1
5 is provided with a rotary power supply terminal section 22 using a slip ring or the like, and a voltage is supplied from a constant voltage power source 23 via the power supply terminal section 22.

Further, in the vicinity of the rotating shaft 18, a first detecting means 25 is provided for detecting the apparent rotational speed ω ₀ of the rotating body 20 with respect to the sample liquid 1.
As the detection means 25, a rotary encoder is used, for example, but a non-contact type sensor may also be used.

The stator 15 of the first motor 11 is rotated by the second motor 12 via a transmission mechanism 27 . As the transmission mechanism 27, for example, a combination of gears, a timing belt and a pulley, or the like is adopted.

The second motor 12 is a servo motor, and the rotation speed ω ₂ of its rotor 30 is controlled by a controller 32. That is, the second motor 12
The apparent rotational speed ω ₀ of the rotating body 20, which is fed back from the detection means 25, is determined in advance by the controller 32.
The stator 15 of the first motor 11 is rotated at a rotation speed ω ₂ in a direction opposite to the rotating shaft 18 via the transmission mechanism 27 so as to maintain the value set in .

The second motor 12 is provided with a second detection means 34 for detecting the rotation speed ω ₂ of the rotor 30. Note that, instead of detecting the rotational speed ω ₂ of the rotor 30, the rotational speed of the stator 15 of the first motor 11 may be detected, which is substantially the same.

A display 36 is connected to the detection means 34. This cover 36 digitally displays, for example, a change in the rotational speed ω ₂ according to a change in viscosity, as will be described later.

Next, the operation of the viscometer 10 having the above configuration will be explained.

The rotating shaft 18 to which the rotating body 20 is connected is rotationally driven by the first motor 11 at a rotational speed ω ₁ .
At the same time, the first motor 11 itself is rotated by the second motor 12 in the opposite direction at a rotation speed ω ₂ . For this reason, the rotating body 2 for the sample liquid 1
The apparent rotational speed of 0 (composite rotational speed) ω ₀ is |ω ₁
|−|ω ₂ |. That is, even if ω ₁ and ω ₂ are large, ω ₀ becomes small. Therefore, it is possible to easily rotate the rotating body 20 with respect to the sump liquid 1 at an extremely low speed close to a stopped state. This rotational speed ω ₀ is the first
is detected by the detection means 25 and fed back to the controller 32.

An appropriate rotational speed ω ₀ is set in advance in the controller 32 . This controller 32 controls the second motor 12 so that even if the rotational speed ω ₁ of the first motor changes due to the generation of a load torque depending on the viscosity of the sample liquid 1, ω ₀ maintains the above set value. change the rotational speed ω ₂ .

In other words, as shown in Fig. 2, even if ω ₁ changes, ω ₀ remains relatively constant, so that the change in rotation speed ω ₁ due to the change in load torque T corresponds to the change Δω ₁ . The rotation speed ω ₂ of the second motor 12 also changes. This amount of change Δω ₂ is then taken out as an output corresponding to the load torque T.

Since there is a certain relationship between the viscosity of the sample liquid 1 and the magnitude of the load torque applied to the rotating body 20, by calculating the constant in advance, Δω ₂
The viscosity can be derived based on . Display 3
6 may digitally display the value of Δω ₂ , but Δω ₂ may be converted into a viscosity value based on a constant input in advance and displayed.

According to the viscometer 10 having the above configuration, the rotational speeds ω ₁ and ω ₂
Even if ω is large, the apparent rotational speed of the rotating body 20 ω ₀
can be made sufficiently small, it is possible to prevent turbulence from occurring in the sample liquid 1, and it is possible to measure the correct viscosity under laminar flow conditions. Furthermore, since the rotational speed of the motors 11 and 12 itself can be high, it is easy to control the rotational speed, and if the variation range of ω ₂ is wide, the rotational speed ω ₀ of the rotating body 20 can be varied from a low speed range to a high speed range. Can be set over a wide range. Moreover, since the viscosity can be measured while keeping the rotational speed ω ₀ constant,
Preferred for measuring viscosity.

Embodiment 2 FIG. 3 shows another embodiment of the present invention. The basic structure and operation and effect of this embodiment are the same as those of the first embodiment, so common parts are given the same reference numerals and explanations are omitted, and only the different parts will be explained below.

In this embodiment, the stator 15 of the first motor 11 is integrated with the rotor 30 of the second motor 12. Therefore, the stator 15 of the first motor 11 rotates together with the rotor 30 of the second motor 12 about the rotating shaft 18 .

As described in the first embodiment, this rotor 30 rotates the stator 15 of the first motor 11 through the rotation of the rotating shaft 18 so that the apparent rotational speed ω ₀ of the rotating body 20 maintains a preset value. It rotates at a rotation speed of ω ₂ in the opposite direction.

According to such a structure, the first motor 11 and the second motor 12 can be arranged coaxially, and the transmission mechanism 27 as described in the first embodiment can be omitted, so that the device can be made more compact.

〔Effect of the invention〕

According to the present invention, it is not only possible to set the rotational speed of the rotating body in contact with the sample liquid to a sufficiently low speed, but also to set the rotational speed of the rotating body in a wide range from a low speed range to a high speed range. Furthermore, even if the load torque varies depending on the viscosity, the rotational speed of the rotating body can be kept constant, which is preferable for measuring viscosity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a viscometer showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the torque and rotational speed of the viscometer shown in FIG. 1, and FIG. The fourth is a schematic diagram of a viscometer showing another embodiment, the fourth is a schematic diagram of a conventional rotational viscometer, and the fifth is a diagram showing the relationship between torque and rotation speed of a motor with drooping characteristics. 1... Sample liquid, 10... Viscometer, 11...
First motor, 12...Second motor, 15...
Stator of first motor, 16... Rotor of first motor, 18... Rotating shaft, 20... Rotating body, 2
5...First detection means, 30...Rotor of second motor, 32...Controller, 34...Second detection means, 36...Display device.

Claims (1)

[Scope of Claims] 1. A first motor having a rotating shaft to which a rotating body in contact with a sample liquid is connected, and having a characteristic that the rotational speed ω ₁ of the rotating shaft changes in response to the magnitude of load torque. and a first detection means for detecting the apparent rotational speed _{ω 0 of} the rotating body with respect to the sample liquid; a second motor that rotates the stator of the motor at a rotation speed ω ₂ in the opposite direction to the rotation axis of the first motor; and a rotation speed ω ₂ of the stator of the first motor or the rotor of the second motor. a second detection means for detecting the rotation speed ω ₂ of the second detection means; and a viscosity value that displays a value related to the rotation speed ω ₂ detected by the second detection means or is calculated based on the rotation speed ω ₂ . A viscometer characterized by being equipped with an indicator that displays.