TECHNICAL FIELD
[0001] The present invention relates to an oil film temperature derivation method, a
temperature derivation device, and a program.
10
BACKGROUND ART
[0002] In the related art, in bearing devices, a configuration in which a lubricant (for example,
lubricating oil or grease) is used to lubricate rotation has been widely used. On the other hand,
by periodically diagnosing a state of rotating parts such as bearing devices, damage and wear
15 can be detected at an early stage to prevent failures of the rotating parts from occurring.
[0003] The bearing device using a lubricant is required to appropriately detect the state related
to the lubricant in order to diagnose the operating state. For example, Patent Literature 1
discloses a method for detecting an oil film thickness of a lubricant and a metal contact ratio in
a rolling device.
20
CITATION LIST
PATENT LITERATURE
[0004] Patent Literature 1: JP-A-2019-211317
25 SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0005] It is very useful to grasp conditions around a lubricant in a device such as a bearing
device to prevent damage to a device. The conditions around the lubricant include a temperature
of an oil film due to the lubricant. In a method of Patent Literature 1, although a film thickness
30 of a lubricant and a metal contact ratio can be derived, the temperature of the lubricant is not
measured. When measuring the temperature of an oil film due to a lubricant whose temperature
is expected to change, there are restrictions according to the installation position of a
temperature sensor and control during measurement based on the measurement principle of the
2
temperature sensor. For example, infrared methods such as thermography require constant
thermal radiation of the object. In addition, in the temperature diagnosis method by means of
thermochromism, or the like, the object needs to exist in a place where the object can be
diagnosed.
5 [0006] In view of the above problems, an object of the present invention is to provide a method
for easily deriving an oil film temperature of a lubricant in a device.
SOLUTION TO PROBLEM
[0007] In order to solve the above-described problems, the present invention has the following
10 configuration. That is, there is provided a temperature derivation method for deriving an oil
film temperature of a lubricant in a device, the temperature derivation method including:
a measurement step of measuring a dielectric constant of the lubricant by applying an
alternating voltage while changing a frequency to an electric circuit configured by the device;
a derivation step of applying the dielectric constant measured in the measurement step
15 to a theoretical formula to derive a relaxation time of the lubricant; and
a calculation step of calculating the oil film temperature by using the relaxation time.
[0008] In addition, another aspect of the present invention has the following configuration.
That is, there is provided a temperature derivation device for detecting an oil film temperature
of a lubricant in a device, the temperature derivation device including:
20 a measurement unit measuring a dielectric constant of the lubricant by applying an
alternating voltage while changing a frequency to an electric circuit configured by the device;
a derivation unit applying the dielectric constant measured by the measurement unit to
a theoretical formula to derive a relaxation time of the lubricant; and
a calculation unit calculating the oil film temperature by using the relaxation time.
25 [0009] In addition, another aspect of the present invention has the following configuration.
That is, the program causing a computer to execute:
a measurement step of measuring a dielectric constant of a lubricant in a device by
applying an alternating voltage while changing a frequency to an electric circuit configured by
the device;
30 a derivation step of applying the dielectric constant measured in the measurement step
to a theoretical formula to derive a relaxation time of the lubricant; and
a calculation step of calculating an oil film temperature of the lubricant by using the
relaxation time.
3
ADVANTAGEOUS EFFECTS OF INVENTION
[0010] According to the present invention, it is possible to provide a method for easily
deriving the oil film temperature of a lubricant in a device.
5
BRIEF DESCRIPTION OF DRAWINGS
[0011] Fig. 1 is a schematic diagram illustrating an example of a configuration of a device
according to one embodiment of the present invention.
Figs. 2A and 2B are diagrams illustrating a relationship between a frequency and a
10 dielectric constant.
Fig. 3 is a diagram illustrating a relationship between a relaxation time and an absolute
temperature.
Fig. 4 is a diagram illustrating derivation of parameters by fitting to a theoretical
formula.
15 Fig. 5 is a diagram illustrating a correlation between a temperature and a relaxation
time.
Fig. 6 is a diagram illustrating an example of a derivation result of an oil film
temperature according to the present embodiment.
Fig. 7 is a flowchart of processing when deriving a temperature according to one
20 embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0012] Hereinafter, an aspect for implementing the present invention is described with
reference to drawings. It is noted that the embodiment described below is one embodiment for
25 describing the invention of the present application, and is not intended to be construed as
limiting the invention of the present application, and all configurations described in the
embodiments are not essential configurations for solving the problems of the present invention.
In addition, in each drawing, the same component is denoted by the same reference number to
indicate a correspondence.
30 [0013]
Hereinafter, a first embodiment according to the present invention will be described.
It is noted that, in the following description, a ball bearing is used as an example of a rolling
bearing, but the present invention is not limited thereto, and can be applied to rolling bearings
4
having other configurations. For example, as types of the rolling bearings to which the present
invention can be applied, there are exemplified deep groove ball bearings, angular contact ball
bearings, tapered roller bearings, cylindrical roller bearings, and self-aligning roller bearings.
[0014] [Device Configuration]
5 Fig. 1 is a schematic configuration diagram illustrating an example of the overall
configuration when performing diagnosis with a diagnosis device 1 according to this
embodiment. In Fig. 1, illustrated are a bearing device 2 to which a temperature derivation
method according to this embodiment is applied and the diagnosis device 1 performing
temperature derivation and diagnosis of an oil film. It is noted that the configuration illustrated
10 in Fig. 1 is an exemplary one, and a different configuration may be used according to a
configuration of the bearing device 2 and the like. In addition, although Fig. 1 illustrates a
configuration in which the bearing device 2 includes one rolling bearing, the present invention
is not limited thereto, and one bearing device 2 may include a plurality of rolling bearings.
[0015] In the bearing device 2, the rolling bearings rotatably support a rotating shaft 7. The
15 rotating shaft 7 is supported by a housing (not illustrated) that covers an outside of the rotating
shaft 7 via the rolling bearing that is a rotating component. The rolling bearing has an outer ring
(outer member) 3 which is a fixing ring fitted inside the housing, an inner ring (inner member)
4 which is a rotating ring fitted on the rotating shaft 7, a plurality of balls (rollers) which are a
plurality of rolling elements 5 arranged between the inner ring 4 and the outer ring 3, and a
20 holder (not illustrated) holding the rolling elements 5 so that rolling elements can roll. Herein,
although the outer ring 3 is fixed in the above-described configuration, the inner ring 4 may be
fixed, and the outer ring 3 may be rotated in the other configurations. In addition, a seal 6 is
provided as a peripheral member for preventing dust from entering the vicinity of the rolling
elements 5 and lubricant from leaking. Friction between the inner ring 4 and the rolling elements
25 5 and friction between the outer ring 3 and the rolling elements 5 are reduced by a predetermined
lubrication method inside the rolling bearing. Although the lubrication method is not
particularly limited, for example, grease lubrication, oil lubrication, or the like is used and is
supplied to the inside of the rolling bearing. Also, the type of lubricant is not particularly limited.
[0016] A motor 10 is a driving motor, and supplies power to the rotating shaft 7 by rotation.
30 The rotating shaft 7 is connected to an LCR meter 8 via a rotation connector 9. The rotation
connector 9 may be configured by using, for example, carbon brushes, but is not limited thereto.
In addition, the bearing device 2 is also electrically connected to the LCR meter 8, and the LCR
meter 8 also functions as an AC power source for the bearing device 2 at this time.