JP2023136931A - Device for measuring bearing friction torque - Google Patents

Abstract

To directly and highly accurately measure friction torque of a bearing single body while applying at least one of radial load and axial load of a magnitude corresponding to an actual operating condition of the bearing.SOLUTION: A device for measuring bearing friction torque comprises: an arm 7 which is fixed to an outer ring 1b of a bearing 1 under test in such a manner that the arm 7 does not contact a housing case 2 and a support bearing 4, and which extends in a direction intersecting an axial direction of a rotary shaft 3; a load cell 9 placed in a position to be pushed by an arm 7 by the rotation of the outer ring 1b of the bearing 1 under test; and a radial load loading mechanism 11 which can apply load to the outer ring 1b of the bearing 1 under test in a radial direction only and can adjust the magnitude of the load to be applied. The torque of arm 7 produced by rotating the rotary shaft 3 with a rotary electric machine 5 is measured with the load cell 9.SELECTED DRAWING: Figure 1

Description

The present invention relates to a measuring device for measuring friction torque of a bearing.

Patent Document 1 discloses that the inner ring of a test bearing is fixed to a rotating shaft and the outer ring is fixed to a bearing box, and when an axial load is applied to the test bearing by pushing the bearing box in the axial direction with a hydrostatic air bearing. A measuring device is disclosed that rotates a rotating shaft and measures the friction torque of a test bearing using a strain gauge.

In Non-Patent Document 1, the inner rings of two test bearings are fixed to one rotating shaft, and the rotating shaft is pushed in the axial direction to apply an axial load to the two test bearings. A measurement in which the total friction torque of two test bearings is measured by rotating a bar attached to a floating housing fixed to the outer rings of the two test bearings and bringing them into contact with a load cell fixed to the mount of the measuring device. A mechanism is disclosed.

Non-Patent Document 2 describes a device in which the inner ring of a test bearing is fixed to a rotating shaft and both ends of the rotating shaft are rotatably supported by two support bearings, and the test bearing is rotated with only a radial load applied. A method is disclosed in which the shaft is rotated, the total friction torque of the test bearing and the support bearing is measured using a torque meter, and then the friction torque of only the support bearing is subtracted to calculate the friction torque of the test bearing.

Japanese Patent Application Publication No. 57-082729

Kyodo Yushi Co., Ltd., KYODO YUSHI TECHNICAL BULLETIN No. 4 “Friction torque of rolling bearings under grease lubrication”, April 1, 2014 <URL: https://www.kyodoyushi.co.jp/knowledge/technical_bulletin/> International Journal of Mechanical Engineering and Application, Volume 4, Issue 3, June 2016, Pages: 130-135

Friction torque must be measured to understand important characteristics of bearings such as ball bearings. It is desirable to measure the friction torque of a bearing while applying a radial load and an axial load to the bearing in accordance with the actual usage conditions of the bearing.

The measuring device disclosed in Patent Document 1 requires the use of a hydrostatic air bearing in order to apply an axial load to the test bearing. However, the static air bearing has a small load carrying capacity, and the upper limit of the axial load that can be applied is limited by the static air bearing. Therefore, with the measuring device disclosed in Patent Document 1, it is difficult to measure friction torque under high load conditions that correspond to the actual usage conditions of the bearing.

Furthermore, the measurement mechanism disclosed in Non-Patent Document 1 is a mechanism that measures the total friction torque of the two test bearings using two test bearings. It is not possible to measure the friction torque of a single unit. Furthermore, since Non-Patent Document 1 does not clearly disclose a structure for applying an axial load evenly to the two test bearings, the axial loads applied to the two test bearings are not necessarily the same.

Furthermore, in the measurement method disclosed in Non-Patent Document 2, after measuring the total friction torque of the test bearing and the support bearing, the friction torque of only the support bearing is subtracted to calculate the friction torque of the test bearing. Therefore, it is not possible to directly measure the friction torque of a single test bearing.

Therefore, an object of the present invention is to provide a measuring device that can directly measure the friction torque of a single bearing with high accuracy while applying at least one of a radial load and an axial load of a magnitude that corresponds to the actual usage conditions of the bearing. With the goal.

A friction torque measuring device for a bearing according to the present invention includes: a storage case that houses a test bearing therein; a rotating shaft that is fixed to an inner ring of the test bearing and rotates integrally with the inner ring; a support bearing that rotatably supports the rotating shaft; a shaft drive unit that can rotate the rotating shaft; By rotating an arm extending in a direction crossing the axial direction and the outer ring of the test bearing, a load is applied only in the radial direction to the load cell placed at a position pushed by the arm and the outer ring of the test bearing. a radial load loading mechanism that can be applied and that can adjust the magnitude of the applied load, and the load cell measures the torque of the arm caused by rotating the rotating shaft with the shaft drive unit. shall be.

In one embodiment of the bearing friction torque measuring device according to the present invention, the arm extends to both sides in a direction intersecting the axial direction of the rotating shaft, and the radial load applying mechanism is arranged on both sides of the arm. The structure may be such that the load is applied only in the radial direction to the outer ring of the test bearing by applying the load evenly in the radial direction of the test bearing.

In one aspect of the bearing friction torque measuring device according to the present invention, the arm is disposed so as to pass through holes formed in the storage case on both sides, and the radial load applying mechanism is arranged such that the arm passes through holes formed in the storage case. The structure may be such that radial load bearing weights are suspended from both sides protruding from the case.

In one aspect of the bearing friction torque measuring device according to the present invention, a storage case that houses a test bearing therein, a rotating shaft that is fixed to an inner ring of the test bearing and rotates integrally with the inner ring; a support bearing that rotatably supports the rotating shaft; a shaft drive unit that can rotate the rotating shaft; An arm extending in a direction intersecting the axial direction of the rotating shaft and the outer ring of the test bearing rotate, and a load cell placed in a position to be pushed by the arm, and the outer ring of the test bearing rotate. an axial load loading mechanism capable of applying a load only in the axial direction of the shaft and adjusting the magnitude of the applied load; It may be measured by

In one aspect of the bearing friction torque measuring device according to the present invention, the arm extends to both sides in a direction intersecting the axial direction of the rotating shaft, and the axial load applying mechanism is arranged on both sides of the arm. A configuration may be adopted in which a load is applied to the outer ring of the test bearing only in the axial direction of the rotating shaft by applying a load uniformly in the axial direction of the test bearing.

In one embodiment of the bearing friction torque measuring device according to the present invention, the arm is disposed so as to pass through holes formed in the storage case on both sides, and the axial load applying mechanism is arranged such that the arm passes through holes formed in the storage case. The structure may be such that axial load bearing weights are connected to both sides protruding from the case.

In one aspect of the bearing friction torque measuring device according to the present invention, the support bearing may be disposed at a distance from the test bearing at least five times the axial width of the test bearing. good.

According to this aspect, since the support bearing is separated from the test bearing, it is possible to reduce the influence of the heat generated by the friction torque generated in the support bearing being transmitted to the test bearing.

One aspect of the bearing friction torque measuring device according to the present invention may include a lubricating oil supply means for supplying lubricating oil at an arbitrary flow rate to the test bearing.

One aspect of the bearing friction torque measuring device according to the present invention includes a flexible tube for supplying the lubricating oil to the test bearing, and discharging the lubricating oil from the test bearing into the storage case. The oil drain port may be provided at a position where it does not come into contact with the storage case.

According to this aspect, the lubricating oil can be supplied and circulated to the test bearing without hindering the rotation of the outer ring and arm of the test bearing.

The present invention can provide a measuring device that can directly measure the friction torque of a single bearing with high precision while applying at least one of a radial load and an axial load of a magnitude that corresponds to the actual usage conditions of the bearing. .

FIG. 1 is a perspective view of a bearing friction torque measuring device according to an embodiment of the present disclosure. 2 is a diagram showing a cross section taken along line AA in FIG. 1. FIG. 2 is a diagram showing a cross section taken along line BB in FIG. 1. FIG. FIG. 2 is a top view of the bearing friction torque measuring device according to the present embodiment. 2 is a graph showing the results of an evaluation test for measurement errors of a load cell using a tester of a bearing friction torque measuring device according to the present embodiment. 2 is a graph showing the results of an evaluation test regarding the reproducibility of measured values of friction torque using a testing machine of the bearing friction torque measuring device according to the present embodiment. It is a graph showing the results of measuring the influence of the amount of supplied oil on the friction torque using a testing machine of the bearing friction torque measuring device of the present embodiment.

Hereinafter, a bearing friction torque measuring device 10 according to an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a perspective view of a friction torque measuring device 10. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a cross-sectional view taken along the line BB in FIG. 1. FIG. 4 is a top view of the friction torque measuring device 10.

As shown in FIGS. 1 and 2, the friction torque measuring device 10 includes a storage case 2 that stores therein a test bearing 1 whose friction torque is to be measured, and a storage case 2 that is fixed to the inner ring 1a of the test bearing 1. A rotating shaft 3 that rotates integrally with the inner ring 1a is provided. The rotating shaft 3 is arranged to extend horizontally, and is rotatably supported by two support bearings 4 provided in the storage case 2. Note that it is preferable that both of the two support bearings 4 be arranged at positions separated from the test bearing 1 by a distance of five times or more the width of the test bearing 1 in the axial direction.

The friction torque measuring device 10 includes a bearing housing 6 fixed to the outer ring 1b of the test bearing 1 so as not to come into contact with the storage case 2 and the support bearing 4. The bearing housing 6 is provided inside the storage case 2 so as to be rotatable coaxially with the rotating shaft 3, integrally with the outer ring 1b. Further, as shown in FIGS. 1 and 3, the friction torque measuring device 10 includes an arm 7 fixed to the bearing housing 6 and extending in a direction intersecting the rotating shaft 3. As shown in FIGS. The arm 7 is arranged to extend horizontally from a central portion fixed to the bearing housing 6 to both sides and pass through holes 2a formed in the storage case 2 on both sides.

As shown in FIG. 3, the friction torque measuring device 10 includes a load cell 9 placed at a position pushed by an arm 7 that rotates and oscillates together with the outer ring 1b of the test bearing 1. For example, the load cell 9 is fixed to the storage case 2 and placed under the arm 7.

Further, as shown in FIG. 4, the friction torque measuring device 10 includes a rotating electric machine 5 as a shaft drive unit that rotates the rotating shaft 3. The rotating electrical machine 5 rotates the rotating shaft 3 by belt drive. The rotating electric machine 5 can adjust the rotation speed of the rotating shaft 3.

The bearing housing 6 was in contact only with the outer ring 1b, the arm 7, and the lubricating oil supply part 8 of the test bearing 1, and was not in contact with other parts. Further, the arm 7 is arranged so as to pass through a hole 2a formed in the storage case 2. That is, the bearing housing 6 and the arm 7 are supported with respect to the rotating shaft 3 supported by the support bearing 4 only via the test bearing 1. Therefore, the outer ring 1b, the bearing housing 6, and the arm 7 of the test bearing 1 prevent the arm 7 from coming into contact with the upper and lower ends of the hole 2a due to the frictional torque between the inner ring 1a and the outer ring 1b accompanying the rotation of the rotating shaft 3. Within this range, they can rotate and oscillate integrally on the same axis as the rotating shaft 3.

When measuring the friction torque of the test bearing 1, the rotating electric machine 5 rotates the rotating shaft 3 in one direction. As shown by the arrow in FIG. 3, when the rotating shaft 3 is rotated clockwise by the rotating electric machine 5, the friction torque of the test bearing 1 causes the outer ring 1b of the test bearing 1, the bearing housing 6, and the arm 7 to rotate. A torque is generated that rotates the clockwise direction. As mentioned above, the bearing housing 6 and the arm 7 are able to rotate and oscillate coaxially with respect to the rotating shaft 3 via only the inner ring 1a and the outer ring 1b, and rotate and oscillate together with the outer ring 1b. By measuring the torque applied to the load cell 9 by the dynamically moving arm 7, the friction torque generated in the outer ring 1b as the inner ring 1a of the test bearing 1 rotates can be measured with high accuracy. At this time, the structure is such that only the influence of the friction torque between the inner ring 1a and the outer ring 1b of the test bearing 1 is transmitted to the load cell 9, and the influence of the friction torque generated in the support bearing 4 is not transmitted to the load cell 9. There is.

Further, since the support bearing 4 is attached to the storage case 2 independently from the bearing housing 6, the friction torque of the test bearing 1 alone can be directly measured. Furthermore, if the two support bearings 4 are arranged at a distance from the test bearing 1 that is five times or more the axial width of the test bearing 1, the friction torque generated in the support bearings 4 Since the influence of heat generation transmitted to the test bearing 1 can be reduced, the friction torque of the test bearing 1 can be measured with even higher accuracy.

The friction torque measuring device 10 further includes a radial load loading mechanism for applying a radial load to the outer ring 1b of the test bearing 1, and an axial load loading mechanism for applying an axial load to the outer ring 1b of the test bearing 1. Equipped with. Both the radial load and the axial load can be applied to the support portion of the outer ring 1b of the test bearing 1 directly or indirectly via a member such as a wire. Note that although this embodiment includes both a radial load loading mechanism and an axial load loading mechanism, an embodiment that includes only one of them is also acceptable.

A radial load is applied to the outer ring 1b in the radial direction of the test bearing 1. In this embodiment, the radial load applying mechanism has a configuration in which a radial load applying weight 11 is suspended from both ends of the arm 7 to apply a radial load to the outer ring 1b. As shown in FIG. 3, the radial load loading mechanism suspends radial load loading weights 11 of the same mass at positions equidistant from the rotating shaft 3 on both sides of the arm 7 protruding from the storage case 2. Accordingly, in addition to the weight of the outer ring 1b, the bearing housing 6, and the arm 7 of the test bearing 1, a radial load can be applied to the outer ring 1b in the radial direction of the test bearing 1, that is, in the downward direction. Since the weight of the suspended radial load bearing weight 11 can be selected arbitrarily, a radial load of a size that corresponds to the actual usage conditions of the test bearing 1 can be applied. Thereby, a radial load can be effectively applied to the outer ring 1b using the radial load applying weight 11. At this time, in order to adjust the imbalance of the left and right balance of the arm 7 to zero, the load application point is set at a distance of more than twice the outside of the load cell 9 in the radial direction of the test bearing 1 and the outer diameter of the outer ring 1b. It is preferable to set it as a position.

However, the means for applying the radial load is not limited to this. For example, a configuration may be adopted in which a wire is connected to both sides of the arm 7 and a load is applied upward to the arm 7 by pulling the wire through a pulley or the like, or a load is applied directly to both sides of the arm 7 using an actuator or the like. It may also be a configuration.

Furthermore, a preload weight 12 can be attached to the end of the arm 7 on the load cell 9 side. If radial load bearing weights 11 of the same mass are suspended from both ends of the arm 7, the arm 7 may be in a balanced state and float off the load cell 9 without contacting the load cell 9. By attaching the preload weight 12 to the arm 7, it is possible to maintain the arm 7 in contact with the load cell 9.

The axial load is applied to the outer ring 1b in the axial direction of the test bearing 1. In this embodiment, the axial load applying mechanism has a configuration that can apply an axial load to the outer ring 1b by connecting axial load applying weights 13 to both sides of the arm 7 via wires 14. FIG. 4 is a top view of the friction torque measuring device 10. Although not shown in FIGS. 1 to 3, as shown in FIG. 4, wires 14 for suspending the axial load bearing weight 13 are connected to both sides of the arm 7, respectively. For example, one wire 14 is connected to each side of the arm 7 protruding from the storage case 2. These two wires 14 both extend from the arm 7 in a direction parallel to the axial direction of the rotating shaft 3 to a pulley 15, change direction in the vertical direction at the pulley 15, and extend downward. Then, the axial load bearing weight 13 can be suspended from the lower end of the wire 14. By suspending the axial load loading weight 13 from the lower end of the wire 14, the arm 7 is pulled in the axial direction of the rotating shaft 3, so that an axial load can be applied to the outer ring 1b of the test bearing 1. In particular, the arm 7 It is possible to precisely apply an axial load to the outer ring 1b of the test bearing 1 without tilting the bearing. Since the weight of the suspended axial load bearing weight 13 can be arbitrarily selected, it is possible to apply an axial load of a magnitude that corresponds to the actual usage conditions of the test bearing 1.

However, the means for applying the axial load is not limited to this. For example, a configuration may be adopted in which a load is applied directly to both sides of the arm 7 using an actuator or the like.

By performing measurement with the radial load loading weight 11 suspended from the arm 7, the friction torque of the test bearing 1 can be measured while a radial load is applied to the test bearing 1. Furthermore, by performing measurements with the axial load bearing weight 13 connected to the arm 7 via the wire 14, the friction torque of the test bearing 1 is measured while an axial load is applied to the test bearing 1. be able to. At this time, it is preferable to apply a radial load or an axial load to the test bearing 1 without applying a rotational torque of at most 10% or more.

The friction torque measuring device 10 also includes a lubricant supply means for supplying a desired flow rate of lubricant to the test bearing 1, and as shown in FIG. A port 16 is provided. Then, lubricating oil can be supplied at an arbitrary flow rate from the lubricating oil supply section 8 to the test bearing 1, and can be discharged from the oil drain port 16 and circulated. It is preferable to use a soft flexible tube for the oil supply path connected to the lubricating oil supply section 8. Further, it is preferable that the oil drain port 16 for discharging lubricating oil into the storage case 2 is provided at a position where it does not come into contact with the storage case 2. By using a soft flexible tube in the oil supply path and providing the oil drain port 16 at a position that does not come into contact with the storage case 2, the rotation of the outer ring 1b of the test bearing 1, the bearing housing 6, and the arm 7 can be prevented. The lubricating oil can be supplied and circulated to the test bearing 1 without being disturbed.

The results of an evaluation test performed using the tester of the friction torque measuring device 10 of this embodiment will be described below. First, an evaluation test of the measurement error of the load cell 9 was conducted using this testing machine. For both this measurement error evaluation test and other evaluation tests to be described later, a compression ultra-compact load cell (model: CLS-5NA-DS) manufactured by Tokyo Sokki Kenkyusho Co., Ltd. was used. In the measurement error evaluation test for the load cell 9, the arm 7 was balanced left and right, and a 12 g preload weight 12 was attached to the end on the load cell 9 side, and a radial load was applied to the end on the load cell 9 side. A weight was suspended at the position where the weight 11 is suspended, and the force applied to the load cell 9 was measured while changing the weight of the weight. The results of the measurement error evaluation test for the load cell 9 are shown in FIG. The measurement error of the load cell 9 with respect to the weight of the weight is less than 2.4%.

Next, an evaluation test was conducted on the reproducibility of the measured value of the friction torque of the test bearing 1 using this testing machine. In this evaluation test, a ball bearing was used as the test bearing 1, commercially available ATF (Toyota genuine auto fluid WS product number: 08886-02305) was used as the test oil supplied to the test bearing 1, and the amount of oil supplied was: Friction torque of the test bearing 1 was measured at 100 ml/min, supply oil temperature: 60° C., radial load: 300 N, and shaft rotation speed: 2,000 to 20,000 r/min. The measurement results are shown in FIG. Comparing the friction torque (n1) measured initially and the friction torque (n2) measured 6 days later under the same conditions, the difference at a shaft rotation speed of 20,000 r/min is 2.7%, and the In evaluating friction torque, it can be determined that it can be measured with good reproducibility.

Next, using this test machine, an evaluation test was conducted to evaluate the effect of the amount of supplied oil on the friction torque. In this evaluation test, a ball bearing was used as the test bearing 1, and the same test oil as used in the test for evaluating the reproducibility of the measured value of friction torque of the test bearing 1 was used. Then, tests were conducted under three conditions: supplied oil temperature: 60°C, radial load: 300 N, supplied oil amount: 40 ml/min, 70 ml/min, and 100 ml/min, and shaft rotation speed: 2000 to 20000 r/min. The friction torque of bearing 1 was measured. The measurement results are shown in FIG. The friction torque under each supply oil amount condition is almost the same when the shaft rotation speed is from 2000 r/min to 10000 r/min, and as mentioned above, this testing machine can measure the friction torque with good reproducibility and high precision. This shows that the measurement is successful. On the other hand, when the rotational speed is 12,000 r/min or higher, there is a tendency for the friction torque to decrease as the amount of supplied oil decreases. For example, when the rotation speed is 20,000 r/min, the friction torque is 4.3% when the oil supply is 100 ml/min, 4.3% when it is 70 ml/min, and 12.8% when it is 40 ml/min. It can be seen that this is decreasing. The reason for this tendency is, for example, under high rotational speed conditions where the rotation speed of the lubricating oil by the rotating ball increases and the centrifugal force applied to the lubricating oil also increases, the amount of oil supplied decreases and the amount of oil is insufficient at the raceway surface etc. It is thought that this is because rolling viscous resistance and stirring resistance, which are factors of friction torque, are reduced accordingly.

1 Test bearing, 1a Inner ring, 1b Outer ring, 2 Storage case, 2a Hole, 3 Rotating shaft, 4 Support bearing, 5 Rotating electric machine, 6 Bearing housing, 7 Arm, 8 Lubricating oil supply section, 9 Load cell, 10 Friction torque measurement device, 11 radial load bearing weight, 12 preload weight, 13 axial load bearing weight, 14 wire, 15 pulley, 16 oil drain port.

Claims (9)

a storage case that houses the test bearing therein;
a rotating shaft fixed to the inner ring of the test bearing and rotating integrally with the inner ring;
a support bearing that rotatably supports the rotating shaft;
a shaft drive unit capable of rotating the rotating shaft;
an arm fixed to the outer ring of the test bearing so as not to come into contact with the storage case and the support bearing, and extending in a direction intersecting the axial direction of the rotating shaft;
a load cell disposed at a position where the outer ring of the test bearing rotates and is pushed by the arm;
a radial load loading mechanism capable of applying a load only in the radial direction to the outer ring of the test bearing and adjusting the magnitude of the applied load;
A friction torque measuring device for a bearing, characterized in that the load cell measures the torque of the arm caused by rotating the rotating shaft with the shaft drive unit. The bearing friction torque measuring device according to claim 1,
The arm extends to both sides in a direction intersecting the axial direction of the rotating shaft,
The radial load loading mechanism is configured to apply a load only in the radial direction to the outer ring of the test bearing by applying a load evenly in the radial direction of the test bearing on both sides of the arm. Friction torque measurement device for bearings. The bearing friction torque measuring device according to claim 2,
The arm is arranged to pass through a hole formed in the storage case on both sides,
A friction torque measuring device for a bearing, wherein the radial load loading mechanism has a configuration in which radial load loading weights are suspended from both sides of the arm protruding from the storage case. a storage case that houses the test bearing therein;
a rotating shaft fixed to the inner ring of the test bearing and rotating integrally with the inner ring;
a support bearing that rotatably supports the rotating shaft;
a shaft drive unit capable of rotating the rotating shaft;
an arm fixed to the outer ring of the test bearing so as not to come into contact with the storage case and the support bearing, and extending in a direction intersecting the axial direction of the rotating shaft;
a load cell disposed at a position where the outer ring of the test bearing rotates and is pushed by the arm;
an axial load loading mechanism capable of applying a load to the outer ring of the test bearing only in the axial direction of the rotating shaft and adjusting the magnitude of the applied load; and rotating the rotating shaft with the shaft drive unit. A friction torque measuring device for a bearing, characterized in that the torque of the arm caused by this is measured by the load cell. The bearing friction torque measuring device according to claim 4,
The arm extends to both sides in a direction intersecting the axial direction of the rotating shaft,
The axial load loading mechanism is configured to apply a load to the outer ring of the test bearing only in the axial direction of the rotating shaft by applying a load evenly in the axial direction of the test bearing on both sides of the arm. A friction torque measuring device for a bearing, characterized in that: The bearing friction torque measuring device according to claim 5,
The arm is arranged to pass through a hole formed in the storage case on both sides,
The friction torque measuring device for a bearing, wherein the axial load loading mechanism is configured such that axial load loading weights are connected to both sides of the arm protruding from the storage case. The bearing friction torque measuring device according to any one of claims 1 to 6,
A friction torque measuring device for a bearing, characterized in that the support bearing is disposed at a distance from the test bearing that is at least five times the axial width of the test bearing. The bearing friction torque measuring device according to any one of claims 1 to 7,
A bearing friction torque measuring device characterized by comprising a lubricating oil supply means for supplying lubricating oil at a desired flow rate to the test bearing. The bearing friction torque measuring device according to claim 8,
comprising a flexible tube for supplying the lubricating oil to the test bearing;
A friction torque measuring device for a bearing, characterized in that an oil drain port for discharging the lubricating oil from the test bearing into the storage case is provided at a position that does not come into contact with the storage case.