JP2011185761A - Device for measuring traction characteristic of lubricant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cost and achieve compactification, concerning a traction characteristic measuring device of a lubricant. <P>SOLUTION: A driven spindle unit 12 is physically separated from a torque meter 17. A metal rotary plate 15 is fixed to the shaft end of the driven spindle 12, and a magnet plate 18 is fixed to the shaft end of a torsion shaft of the torque meter 17, and both plates 15, 18 are faced. When a rotating power is transferred from a driving spindle unit 11 to the driven spindle through test pieces 11a, 12a, since the rotary plate 15 rotating in a body crosses a magnetic flux of a permanent magnet 18a of the magnet plate 18, a rotational resistance is generated in the rotary plate 15 by electromagnetic induction, and the driven spindle 12 is braked. The reaction force is given to the magnet plate 18, and the torsion shaft of the torque meter 17 is twisted, and a torque of the driven spindle 12 is measured. A mechanical braking unit which is used in a conventional device can be eliminated, thereby cost reduction and miniaturization can be achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for measuring traction characteristics of a lubricant used for rolling parts.

As a power transmission system using friction at the time of rolling contact of rolling parts, a traction drive used for a continuously variable transmission or the like is known.
In the traction drive, a lubricant is used in order to prevent the rolling surface from being worn and the like, and power transmission is performed via a lubricant film formed on the rolling surface. Therefore, the state of transmission changes depending on the properties of the lubricant used, that is, the traction characteristics.
Here, the traction characteristic is represented by the relationship between the traction coefficient and the slip rate. When selecting a lubricant according to the type and application of rolling parts such as a traction drive, it is necessary to measure these numerical values in advance.

As an apparatus for measuring the traction characteristic of such a lubricant, one shown in FIGS. 4 and 5 is known (see Patent Document 1).
As shown in the figure, a conventional lubricant traction characteristic measuring device 20 has a driving spindle unit 21 and a driven spindle unit 22 arranged on a pedestal so that their spindles are parallel to each other. A cylindrical driving side test piece 21a and a driven side test piece 22a to which a lubricant is added are respectively mounted.
The drive spindle is driven to rotate, and the drive side test piece 21a attached thereto is pressed against the follower side test piece 22a attached to the follower spindle as indicated by an arrow in the figure so that the driven spindle is rotated by the frictional force. It has become.

Further, a torque meter 23 and a mechanical brake unit 24 are sequentially coupled to the back portion of the driven spindle unit 22 with a coupling 25. When the mechanical brake unit 24 brakes the rotation of the driven spindle, the torsion shaft 23a of the torque meter 23 is twisted, and the torque is measured based on the displacement amount of the twist. The traction coefficient is calculated based on the magnitude of the torque, the magnitude of the pressing load between the test pieces 21a and 22a, and the diameter of the test piece 22a.
Further, the rotational speeds of the driving spindle and the driven spindle are respectively measured by a rotary encoder or the like, and the slip ratio is calculated based on the difference.
Therefore, the traction characteristic of the lubricant is determined by sequentially measuring the slip ratio and the traction coefficient while changing the braking force by the mechanical brake unit 24.
For example, as shown in FIG. 3, the traction characteristic can be expressed as a traction curve by plotting the slip rate on the horizontal axis and the measured value on the vertical axis and the measured value on the vertical axis.

JP 2009-293965 A

  In such a conventional traction characteristic measuring apparatus, since the two elements of the torque meter and the mechanical brake unit are physically coupled to the back of the driven spindle unit as described above, the entire apparatus is increased in size and cost. There was also a problem that increased.

  Therefore, the problem to be solved by the present invention is to reduce the cost and the size of the lubricant traction characteristic measuring device.

  In order to solve the above problems, in the lubricant traction characteristic measuring device according to the invention, instead of eliminating the mechanical brake unit and physically separating the torque meter from the driven spindle, a rotary brake by electromagnetic induction is applied to the driven spindle. A configuration was adopted in which an electromagnetic induction mechanism for twisting the torsion shaft of the torque meter by the electromagnetic reaction force was added.

By eliminating the large and expensive mechanical brake unit and eliminating the coupling between the torque meter and the driven spindle, the entire traction characteristic measuring device can be made compact and low in cost.
In addition, the driven spindle can be rotated and the torsion shaft can be twisted to measure the magnitude of torque, so that the performance is not inferior to that of a conventional traction characteristic measuring device.

  More specifically, the lubricant traction characteristic measuring apparatus according to the present invention includes a drive spindle that can be mounted on a shaft of a cylindrical driving side test piece to which a lubricant is added and can be driven to rotate, and is parallel to the driving spindle. And a driven spindle capable of mounting a cylindrical driven-side test piece to which the shaft ends are adjacent to each other and to which a lubricant is added to the shaft end, and a driving-side test piece mounted on the driving spindle to the driven A pressure mechanism that presses against a driven test piece mounted on the spindle to transmit rotational power to the driven spindle, a rotation measuring mechanism that measures the rotational speed of the drive spindle and the driven spindle, and a physical separation from the driven spindle A torque meter for measuring the torque based on the torsional displacement of the torsion shaft, and a rotational blur caused by electromagnetic induction on the rotating driven spindle. Given key and an electromagnetic induction mechanism for giving a twist to the torsion shaft of the torque meter by its reaction force, it was a structure comprising a.

As a more specific configuration of the electromagnetic induction mechanism, a metal rotating plate that can rotate in the circumferential direction integrally with the driven spindle, and a shaft end of the torsion shaft of the torque meter that faces the rotating plate in a non-contact manner. And a plurality of permanent magnets fixed in parallel in the circumferential direction.
If comprised in this way, the rotating plate which rotates integrally with a driven spindle will cross the magnetic flux of a permanent magnet, and the resistance force (brake) to the rotation direction of a rotating plate will arise by electromagnetic induction. In addition, due to the electromagnetic reaction, the permanent magnet is pushed in the reverse direction with a force substantially equal to the resistance force, thereby twisting the torsion shaft of the torque meter.

Further, in order to freely change the magnitude of the rotational braking force and torque generated by electromagnetic induction, a moving mechanism that moves the torque meter so as to be able to approach and move away from the rotating plate, or the rotational speed of the driving spindle is set. It is preferable to provide a speed changing mechanism for changing the measuring apparatus.
In any case, since the number of magnetic fluxes traversed by the rotating plate per unit time changes, the rotational braking force and the magnitude of torque also change.

  Furthermore, in order to suppress heat generation of the rotating plate due to electromagnetic induction, it is preferable to provide a cooling mechanism for cooling the rotating plate in the measuring apparatus.

  If this invention is regarded as a method for measuring the traction characteristics of a lubricant, cylindrical test pieces are respectively attached to the shaft ends of a drive spindle and a driven spindle that are arranged in parallel, and the test pieces to which a lubricant is added are pressed against each other. A step of transmitting rotational power to the driven spindle and a torque meter for measuring torque based on the torsional displacement of the torsion shaft are prepared, and a rotary brake is applied to the rotating driven spindle by electromagnetic induction, and its reaction is used to torsion. It is understood that the method includes a step of twisting the shaft, and a step of measuring the number of rotations of the drive spindle and the driven spindle and the amount of twist displacement of the torsion shaft a plurality of times while changing the force of the rotary brake. Is done.

  Since the above-described configuration utilizing the principle of electromagnetic induction is employed in the lubricant traction characteristic measuring apparatus according to the invention, its cost reduction and compactness are realized.

Plan view of the traction characteristic measuring apparatus of the embodiment The perspective view of the traction characteristic measuring device of an embodiment The figure which shows the example of the traction characteristic measured with embodiment and the conventional traction characteristic measuring apparatus Plan view of a conventional traction characteristic measuring device Perspective view of a conventional traction characteristic measuring device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings schematically show the principle of the present invention.

The traction characteristic measuring device 10 of the embodiment shown in FIGS. 1 and 2 is used for measuring the traction characteristic of a lubricant, that is, the traction coefficient and the slip ratio.
The traction characteristic measuring apparatus 10 includes a driving spindle unit 11, a driven spindle unit 12, and a torque meter 17 supported on a pedestal as main components.

First, the drive spindle unit 11 has a drive spindle that can rotate around an axis, and is movable along a rail 11c in a direction substantially orthogonal to the axial direction of the drive spindle.
A cylindrical driving side test piece 11a is mounted on the shaft end of the driving spindle on the side close to the driven spindle unit 12, and rotates integrally. A lubricant to be measured can be added to the driving side test piece 11a by a known method such as an oil bath.

  A pulley 11b is attached to the shaft end of the drive spindle far from the driven spindle unit 12, and rotational power is applied to the drive spindle from a motor (not shown) via a belt. Incidentally, as the motor, a known motor having a variable rotation speed can be used, and in this case, the rotation speed of the drive spindle can be changed.

Next, the driven spindle unit 12 has a driven spindle that can rotate around its axis, and is arranged so that the driven spindle and the driving spindle are parallel to each other and the shaft ends of both spindles are close to each other. Yes.
A cylindrical driven-side test piece 12a is mounted on the shaft end of the driven spindle close to the drive spindle unit 11, and rotates integrally.
The outer peripheral surface of the driven side test piece 12a faces and is close to the outer peripheral surface of the driving side test piece 11a, and the lubricant to be measured can be added to the driven side test piece 12a.

  Further, in the vicinity of the drive side test piece 11 a mounted on the drive spindle unit 11, there is a pusher 13 (pressure mechanism) that presses the drive side test piece 11 a against the driven side test piece 12 a mounted on the driven spindle unit 12. Has been placed. The amount of protrusion of the pusher 13 can be adjusted, whereby the magnitude of the load for pressing the driving side test piece 11a against the driven side test piece 12a can be adjusted.

  Thus, when the drive side test piece 11a rotating integrally with the drive spindle is pressed against the driven side test piece 12a by the pusher 13, the driven side test piece 12a and the driven side spindle are rotated by the frictional force. Here, the rotation speeds of the drive spindle and the driven spindle can be measured by the rotary encoder 14 (rotation measurement mechanism).

A rotating plate 15 is fixed to the shaft end of the driven spindle far from the drive spindle unit 11. The rotating plate 15 is a metal disk, and is fixed so that the surface thereof is orthogonal to the axial direction of the driven spindle and the center thereof coincides with the axis of the driven spindle. For this reason, when the driven spindle rotates, the rotating plate 15 rotates around the center.
A fan 16 (cooling mechanism) is disposed in the vicinity of the rotating plate 15 so that the rotating plate 15 can be cooled.

On the other hand, a torque meter 17 is disposed at a position away from the driven spindle unit 12 in the opposite direction to the drive spindle unit 11.
The torque meter 17 has a torsion shaft 17a extending in parallel with the drive spindle and the driven spindle. The torsion shaft 17a is fixed around the shaft so as not to rotate, and a torsional displacement is generated when torque is applied. The magnitude of torque can be measured by detecting the amount of torsional displacement of the torsion shaft 17a using a strain gauge attached thereto.

Further, a disc-shaped magnet plate 18 facing the rotating plate 15 fixed to the shaft end of the driven spindle is fixed to the shaft end of the torsion shaft 17a, and there are a plurality of magnet plates 18 arranged in parallel in the circumferential direction. Permanent magnet 18a.
As will be described later, the permanent magnet 18a and the rotating plate 15 constitute an electromagnetic induction mechanism.
Further, since the torque meter 17 is mounted on a movable table 19 that can move in a three-dimensional direction with respect to the pedestal, the magnet plate 18 can be moved toward and away from the rotating plate 15. Yes.

  The configuration of the traction characteristic measuring apparatus 10 of the embodiment is as described above, and the operation thereof will be described next.

  Now, the rotation of the driving spindle is started, and the driving side test piece 11a that rotates integrally with the driving spindle is pressed against the driven side test piece 12a by the pusher 13 with a predetermined load P (N), and the driven side test piece is caused by the frictional force. 12a and driven spindle are rotated. Here, a lubricant to be measured is added to the driving side test piece 11a and the driven side test piece 12a to form a lubricant film.

When the driven spindle rotates, the rotating plate 15 also rotates together, so that the rotating plate 15 crosses the magnetic flux of the permanent magnet 18a of the opposing magnet plate 18. Therefore, due to electromagnetic induction, a force (rotational brake) in the direction opposite to the rotation direction is generated on the rotary plate 15 and the driven spindle.
The heat generated in the rotating plate 15 due to electromagnetic induction is cooled by the fan 16 and thus overheating is prevented.

Due to the rotation brake, slip occurs between the driving side test piece 11a and the driven side test piece 12a, and the rotational speed Na of the driving spindle and the rotational speed Nb of the driven spindle differ. By measuring the rotational speeds Na and Nb (rpm) of both spindles by the rotary encoder 14, the slip ratio λ is calculated based on the following equation (1).
λ = {(Na−Nb) / Na} × 100 (1)

Further, due to the law of action and reaction, a force substantially equal to the reverse direction of the rotary brake acts on the magnet plate 18 and the torsion shaft 17a, and a torsional displacement occurs on the torsion shaft 17a. Based on the amount of torsional displacement, the torque T (N · m) applied to the driven spindle is measured.
From this and the above-mentioned pressing load P (N) and the diameter r (m) of the driven side test piece, the traction coefficient μ is calculated based on the following equation (2).
μ = T / (P ・ r) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2)

When the position of the torque meter 17 is moved by the moving table 19 so that the magnet plate 18 approaches or separates from the rotating plate 15 or the rotational speed of the motor that drives the driving spindle is changed, the rotating plate 15 is moved to unit time. Therefore, the magnitude of the rotary brake with respect to the driven spindle changes.
Sequentially measure the slip rate and traction coefficient while changing the size of the rotary brake by either method, and plot the slip ratio on the horizontal axis and the traction coefficient on the vertical axis to express the traction characteristics as a traction curve. be able to.

FIG. 3 shows an example of the measurement. In this example, the maximum contact surface pressure of the driving side test piece 11a and the driven side test piece 12a is 4.2 GPa, ● is a measurement value by the traction characteristic measuring apparatus 10 of the embodiment, and ○ is shown in FIGS. The measured value by the conventional traction characteristic measuring apparatus 20 is shown.
As can be seen from the table, the traction characteristic measurement device 10 of the embodiment obtained almost the same measurement results as the conventional traction characteristic measurement device 20.

  In order to improve the accuracy of the measured value, it is desirable that the friction between the driven spindle and the bearing in the driven spindle unit 12 is as small as possible. Therefore, as a lubrication method, oil bath lubrication, oil mist lubrication, and jet lubrication, which have higher lubrication performance than grease lubrication, are preferable.

In the above-described embodiment, the pusher 13, the rotary encoder 14, the fan 16, the moving base 19, and the motor having a variable rotation speed are examples of a pressurizing mechanism, a rotation measuring mechanism, a cooling mechanism, a moving mechanism, and a variable speed mechanism, respectively. A known mechanism is applicable.
Further, if there is a variable speed mechanism of the drive spindle, the moving mechanism of the torque meter 17 can be omitted, and if the heat generation amount of the rotating plate 15 is small, the cooling mechanism can be omitted.

DESCRIPTION OF SYMBOLS 10 Traction characteristic measuring apparatus 11 Embodiment 11 Drive spindle unit 11a Drive side test piece 11b Pulley 11c Rail 12 Driven spindle unit 12a Drive side test piece 13 Pusher 14 Rotary encoder 15 Rotary plate 16 Fan 17 Torque meter 17a Torsion shaft 18 Magnet plate 18a Permanent magnet 19 Moving table 20 Conventional traction characteristic measuring device 21 Drive spindle unit 21a Drive side test piece 22 Driven spindle unit 22a Drive side test piece 23 Torque meter 23a Torsion shaft 24 Mechanical brake unit 25 Coupling

Claims (6)

A cylindrical driving side test piece to which a lubricant is added can be mounted on the shaft end, and a driving spindle that can be driven to rotate.
A driven spindle that is arranged in parallel to the drive spindle and whose shaft ends are adjacent to each other, and a cylindrical driven test piece to which a lubricant is added can be mounted on the shaft end;
A pressurizing mechanism for pressing the drive side test piece mounted on the drive spindle against the driven side test piece mounted on the driven spindle to transmit rotational power to the driven spindle;
A rotation measuring mechanism for measuring the number of rotations of the drive spindle and the driven spindle;
A torque meter physically separated from the driven spindle and measuring torque based on torsional displacement of the torsion shaft;
An apparatus for measuring a traction characteristic of a lubricant, comprising: an electromagnetic induction mechanism that applies a rotational brake by electromagnetic induction to the driven spindle that rotates, and that twists a torsion shaft of the torque meter by a reaction force thereof. The electromagnetic induction mechanism is
A metal rotating plate that can rotate in the circumferential direction integrally with the driven spindle;
2. The lubricant traction characteristic measuring device according to claim 1, comprising a plurality of permanent magnets that face the rotating plate in a non-contact manner and are fixed in parallel to a shaft end of a torsion shaft of the torque meter in a circumferential direction. .   The lubricant traction characteristic measuring device according to claim 2, further comprising a moving mechanism that moves the torque meter so as to be able to approach and leave the rotating plate.   4. The lubricant traction characteristic measuring device according to claim 2, further comprising a speed variable mechanism of the drive spindle.   The apparatus for measuring a traction characteristic of a lubricant according to any one of claims 2 to 4, further comprising a cooling mechanism for cooling the rotating plate. Cylindrical test pieces are attached to the shaft ends of the drive spindle and the driven spindle arranged in parallel, respectively, and the rotational force of the drive spindle is transmitted to the driven spindle by pressing the test pieces to which the lubricant is added;
Preparing a torque meter for measuring torque based on the torsional displacement of the torsion shaft, applying a rotational brake to the rotating driven spindle by electromagnetic induction, and twisting the torsion shaft by its reaction force;
Measuring the number of rotations of the driving spindle and the driven spindle and the amount of torsional displacement of the torsion shaft a plurality of times while changing the force of the rotary brake.

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