JP2001165789A - Method for measuring load acting on bearing for supporting rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a load acting on a bearing without performing any execution to the bearing part. SOLUTION: After a strain gauge 4 is applied to a housing part where it is considered that distortion occurs, a static load is applied to a bearing part for measuring distortion, a measurement point with high sensitivity for the load is measured, and at the same time the relation expression between the applied load and distortion being generated by the load is obtained in advance. Then, the strain gauge 4 is applied to the selected measurement point and a dynamic load is applied, and a load operating on the bearing is obtained from the relation expression between the dynamic distortion being measured by the strain gauge 4, a load that has been obtained in advance, and distortion, thus directly and accurately measuring the change in the load of the bearing according to the shape in the bearing and that of the rotary shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a load acting on a bearing for supporting a rotating body, and more particularly to a method for accurately measuring a load acting on a bearing while the rotating body is rotating.

[0002]

2. Description of the Related Art For example, it is necessary to measure the load acting on a rolling bearing during operation in order to know the durability of rolling bearings incorporated in various mechanical devices and to help design a rotating shaft incorporated in these mechanical devices. is there. As a method of measuring the bearing load used at this time, for example,
No. 10027 is disclosed.

The bearing load measuring method disclosed in Japanese Patent Publication No. 52-10027 discloses a method for measuring a bearing load, as shown in FIGS. 16 and 17, in which a rotating shaft 3 is rotatably supported inside a cylindrical housing 1. A pair of rolling bearings 2 provided
The measurement of the load acting on a and 2b is performed as follows.

That is, notches 2ab, 2bb having a shape as shown in FIG. 17 are provided on the outer peripheral surfaces of the outer rings 2aa, 2ba constituting the rolling bearings 2a, 2b, and strain gauges are provided on the bottom surfaces of these notches 2ab, 2bb. Stick 4
The output signal of the strain gauge 4 is taken out through the conductor 5.

In this way, the outer races 2aa, 2aa, 2aa, 2aa
Since ba is elastically deformed, each strain gauge 4 detects this elastic deformation. The detected elastic deformation is sent to an arithmetic unit (not shown) via the conductor 5, and the arithmetic unit calculates a load acting between the housing 1 and the rotating shaft 3 from the elastic deformation.

In addition, the notches 2ab, 2bb
To the inner races 2ac, 2 constituting the rolling bearings 2a, 2b.
If formed on the inner peripheral surface of bc and the strain gauge 4 is attached to the bottom surface of the notches 2ab and 2bb, the load in a state where the outer rings 2aa and 2ba rotate can be measured. In addition,
Reference numerals 2ad and 2bd in FIG. 16 denote rolling elements provided between the outer raceway provided on the inner peripheral surface of each outer race 2aa and 2ba and the inner raceway formed on the outer peripheral surface of each inner race 2ac and 2bc.

[0007]

However, the method for measuring a bearing load disclosed in Japanese Patent Publication No. 52-10027 has a drawback that accurate measurement cannot always be performed.

That is, the cutouts formed on the outer peripheral surface of the outer race and the inner peripheral surface of the inner race are for installing a strain gauge for load measurement, and are not inherently provided in the bearing. For this reason, the thickness of the part where the strain is measured becomes thinner than the original thickness of the bearing, and the elastic deformation state of each outer ring and inner ring differs from the actual bearing. Is more likely to occur.

In particular, the notch is partially formed in the circumferential direction,
Alternatively, since the slits are provided intermittently, stress concentration occurs in a portion where the notch is formed. As a result, the stress distribution in the circumferential direction is different from the original bearing, and accurate measurement cannot be performed.

[0010] In order to solve such a drawback,
In JP-A-9-61268, as shown in FIG. 18, the outer ring raceways 2ae, 2ae,
A method is disclosed in which concave grooves 2af, 2bf are formed in parallel with 2be, a strain gauge 4 is attached to the concave grooves 2af, 2bf, and a load is calculated based on an output signal from the strain gauge 4. I have.

However, Japanese Patent Application Laid-Open No. 9-61268 discloses
Also, in the method disclosed in the above-mentioned publication, since the groove is formed for attaching the strain gauge, the stress distribution generated in the bearing is different from the original bearing. In particular, as a result of the deformation of the rotary shaft 3, as shown in FIG.
In the case of contact with (2b), the stress distribution in the axial direction differs from the original bearing, and accurate measurement cannot be performed.

The present invention has been made in view of the above-mentioned problems, and measures a dynamic strain by using a strain gauge attached to a housing without performing any processing on a bearing portion. It is an object of the present invention to provide a method of measuring a load acting on a bearing by using a load-strain relation statically obtained from a value.

[0013]

In order to achieve the above-mentioned object, a method for measuring a load acting on a bearing supporting a rotating body according to the present invention comprises the steps of: attaching a strain gauge to a housing portion; Apply static load to
Selection of a measurement point having high sensitivity to the load, a relational expression between the loaded load and strain is obtained in advance, and then the dynamic strain measured by the strain gauge attached to the selected point and the load obtained in advance The load acting on the bearing is determined from the relational expression between the load and the strain. By doing so, the load acting on the bearing can be accurately measured at a small number of measurement points without performing any processing on the bearing portion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When a load acts on a bearing, the load naturally acts on a housing in which the bearing is mounted, and the housing is elastically deformed. Due to this elastic deformation,
Distortion corresponding to the load also occurs in the housing. Therefore, it is possible to determine the load acting on the bearing from the distortion.

According to such a method, since the bearing and the housing are not processed, both in the circumferential direction and in the axial direction,
It has the original stress distribution. Therefore, it is possible to more accurately measure the load acting on the bearing.

The method for measuring the load acting on the bearing supporting the rotating body according to the present invention is based on the above-described concept. As shown in FIG. After sticking, a static load is applied to the bearing portion to perform a strain measurement, and a measurement point having high sensitivity to the load is selected, and based on the measurement result at the selected measurement point, the applied load is measured. And the relational expression of the strain caused by the load is obtained in advance, then a dynamic load is applied by attaching a strain gauge to the selected measurement point, and the dynamic strain measured by this strain gauge and the The load acting on the bearing is obtained from the relational expression between the load and the strain that has been obtained.

In the measuring method of the present invention, a measuring point having a high sensitivity to a load means, for example, as shown in FIG.
The point having the relationship of 1. When such a measurement point is not selected, that is, when a point that does not satisfy the above-described conditions as shown in FIG. 3, that is, a point having low sensitivity to load is selected as the measurement point, accurate load measurement is performed. It is not possible.

In the above-described measuring method of the present invention, it is sufficient that the loading direction and the applied load can be determined at a single measurement point.
If these cannot be determined at a single measurement point, it is necessary to select the required measurement points for each. At this time, a load test considering the axial deformation of the rotating shaft was also performed by forcibly tilting the housing and performing a load test, etc., and based on the measurement results, the relational equation between load and strain was calculated. It is desirable to ask for it.

In the case where there are a plurality of bearings and the shapes of the bearings are significantly different, it is necessary to perform a static loading test for each bearing in order to select a measurement point. , A measurement point may be selected in a typical bearing. However, even in this case, in order to improve the accuracy of the bearing load, it is desirable to perform a static loading test at the selected measurement point and obtain the relational expression between the load and the strain.

In the above-described measuring method of the present invention, when a strain gauge is attached to the same position of the housing portion on both surfaces of the bearing portion, and the load acting on the bearing is determined from the average of the measured values of these strain gauges. In particular, it is possible to more accurately measure the load acting on the bearing when the bearing is in a partial contact state due to the deformation of the rotating shaft.

By the way, the fluctuation factors of the bearing load acting on the rotating body, for example, the bearing supporting the crankshaft of the engine, include fluctuations in the cylinder pressure (explosive force), fluctuations in the ignition timing, fluctuations in the shaft torque, fluctuations in the engine speed. Of these, there are fluctuations in the in-cylinder pressure (explosive power) and
It is considered that the influence of the fluctuation of the engine speed is large.

Each of these fluctuation factors does not occur regularly, but basically occurs randomly. Therefore, when measuring the bearing load that changes due to such randomly occurring fluctuation factors, it is unknown whether the value is general data or special data,
It is not appropriate as a method for evaluating the bearing load.

In connection with this, even if, for example, the maximum value during the measurement of the bearing load of 100 times is set to the maximum value during the measurement, it cannot be said that no further bearing load occurs at the 101st time. . From this, it cannot be said that no matter how many times the number of measurements is increased, the maximum value does not occur at the next measurement.

Also, when designing a rotating body, usually, 1
Process, for example, two revolutions (7
20 °), one revolution (36
(0 °), a certain safety factor is added to the maximum value of the bearing load constantly applied. From this, it can be said that obtaining an average load value is easier to use and more realistic than obtaining a special load value.

Further, when evaluating data that changes at random, usually a plurality of data are statistically processed.
This statistical processing requires a plurality of data under one condition. And in this statistical process,
The simplest process is the averaging process.

In view of the above, in the above-described measuring method of the present invention, when measuring a plurality of units with one step of the rotating body as one unit, and obtaining the load acting on the bearing from the average value of these strains, It is clear that the fluctuation of the bearing load by each unit described above can be suppressed.

In the above-described measuring method of the present invention, in order to measure the load more accurately, it is necessary to consider individual differences of the housing. To this end, it is essential to determine the relational expression between load and strain using a housing that is actually used.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The results of various experiments performed to confirm the effects of the method for measuring the load acting on a bearing supporting a rotating body according to the present invention will be described below. In this experiment, the load acting on the bearing of the in-line 4-cylinder 4-cycle engine was measured.

An in-line four-cylinder four-cycle engine (hereinafter simply referred to as an "engine") has five bearings for supporting a crankshaft, and each bearing has almost the same shape. 4, the strain gauge 4 is attached to the position shown in FIG. 4, and as shown in FIG. 5, the loading jig is fixed to the housing 7a holding the center bearing of the engine 7 fixed by the jig 6 for fixing the engine. A static loading test was performed via the tool 8. The loading test was performed manually by applying a load in the vertical direction of the engine and in each of 45 ° and 90 ° directions.

By the way, since the crankshaft is deformed in the axial direction, in this test, as shown in FIG. 7, the strain gauge 4 is attached to the housing 7a on both sides of the bearing at the same position as in FIG. The load acting on the bearing was measured by using the average of the output values at the same position.

When the above-described loading test was performed and high-sensitivity measurement points and measurement points capable of judging directions were selected, the respective points shown in FIGS. 6 and 7 were selected. That is, the determination of the directionality of the load, and when the load is acting upward, the output values of the strain gauges 4aa, 4ba, 4ab, 4bb are used, and when the load is acting downward, Strain gauge 4ac,
4bc, 4ad, 4bd, 4ae, 4be, 4af, 4
The load was determined by using the output value of bf.

Next, as shown in FIG. 8, the engine 7 is driven while the transmission 10 and the dynamo 11 are directly connected to the engine 7 mounted via the engine mount 9, and the bearing load during driving is measured. did. The driving conditions of the engine 7 in the test are as follows.
The test was carried out under two conditions of 000 rpm under full load (100% torque absorption). The test was performed on three shapes shown in Table 1 below to measure the difference in bearing load depending on the shape of the crankshaft.

[0033]

[Table 1]

The measurement results are shown in FIGS. 9 to 14 and Table 2. 9 to 14 show the measurement results showing the relationship between the rotation angle of the crankshaft and the bearing load when the number of revolutions of the engine and the shape of the crankshaft are changed, and Table 2 shows the maximum load value among them. showed that.

9 to 14, the calculated values are shown by thin lines in addition to the measurement results. From these, it can be seen that the calculation results and the measurement results agree well. From this, it is understood that the load measuring method according to the present invention can accurately measure the bearing load during rotation of the engine.

The calculated values shown in FIGS. 9 to 14 are values obtained by a method as shown in the flowchart of FIG. First, the mass and the position of the center of gravity of the piston and the connecting rod and the shape of the original crankshaft are read (S1).
0). Next, from the relationship data between the crank angle and the cylinder pressure, the maximum cylinder pressure Pmax and the crank angle θPmax at that time are obtained.
A series of data of the engine speed N and the engine speed N is read as one type of engine operating condition (S12). Next, the inertial force (S14) and the gas pressure (S16) acting on the crankshaft are calculated based on the read numerical values (S10, 12). Next, a load acting on the crankshaft is calculated from the calculated (S14, 16) inertia force and gas pressure (S1).
8). Finally, the load of each journal bearing is calculated using a stepped beam model (S20).

In the above test, the bearing load during the operation of the four-cycle engine was measured, so that the crank rotation angle was 720 degrees, that is, two rotations of the crankshaft were measured as one unit. This is because, in the case of a four-cycle engine, one stroke corresponds to two revolutions of the crankshaft. Therefore, when one rotation corresponds to one stroke as in a rotating shaft of a two-cycle engine or an electric motor, it is needless to say that the rotation angle is measured at 360 degrees, that is, one rotation is defined as one unit. If the unit of one stroke is other than the above, for example, three rotations, four rotations, or more, it is necessary to select one unit according to the number of rotations.

In the above test, the measurement results are shown for only one unit under each condition. However, when the fluctuation of the bearing load due to the measurement time is considered, several units are measured, and the average value of these is adopted. It is desirable to know the steady load for designing the crankshaft and the bearing.

[0039]

[Table 2]

[0040]

As described above, according to the method for measuring the load acting on the bearing supporting the rotating body according to the present invention, the method of measuring the load applied to the housing without applying any processing to the bearing portion is as small as possible. The dynamic strain is measured using a number of strain gauges, and from this measured value, the load acting on the bearing is measured using a load-strain relational expression obtained statically. The change in the bearing load due to the shape can be measured directly and with high accuracy at a small number of measurement points.

[Brief description of the drawings]

FIG. 1 is a flowchart of a load measuring method of the present invention.

FIG. 2 is a load-strain diagram illustrating measurement points having high sensitivity to load.

FIG. 3 is a load-strain diagram illustrating measurement points having low sensitivity to load.

FIG. 4 is a diagram illustrating an example of a strain measurement point for selecting a load measurement point when the load measurement method of the present invention is performed.

FIG. 5 is an explanatory diagram of a static loading test when the load measuring method of the present invention is performed.

FIG. 6 is a front view of a bearing portion showing an example of a load measurement point selected to carry out the load measurement method of the present invention.

FIG. 7 is a side view of a bearing portion showing an example of a load measuring point selected to carry out the load measuring method of the present invention.

FIG. 8 is an explanatory diagram of an engine test when the load measuring method of the present invention is performed.

FIG. 9 shows a case where one crankshaft is used and the number of revolutions is 2000 rpm.
FIG. 8 is a diagram showing a result of measuring a bearing load in the case of m.

FIG. 10 shows the case where one crankshaft is used and the number of revolutions is 4000r.
It is a figure showing the result of having measured bearing load in the case of pm.

FIG. 11 shows a case where the number of revolutions is 2000 r using the crankshaft of FIG.
It is a figure showing the result of having measured bearing load in the case of pm.

FIG. 12 shows a case where the number of revolutions is 4000r using the crankshaft of FIG.
It is a figure showing the result of having measured bearing load in the case of pm.

FIG. 13 shows a case where the number of rotations is 2000r using a crankshaft of 3
It is a figure showing the result of having measured bearing load in the case of pm.

FIG. 14 shows a case where a crankshaft of 3 is used and the number of revolutions is 4000r.
It is a figure showing the result of having measured bearing load in the case of pm.

FIG. 15 is a flowchart illustrating a method of obtaining the calculated values shown in FIGS. 9 to 14.

FIG. 16 is a partial sectional view showing an example of a conventional measuring method.

FIG. 17 is a partial sectional view of an outer ring in a bearing used in a conventional measuring method.

FIG. 18 is a partial cross-sectional view showing another example of the conventional measuring method.

FIG. 19 is a diagram illustrating a state in which the bearing and the rotating shaft partially contact in the axial direction due to deformation of the rotating shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 3 Rotation axis 4 Strain gauge

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Miyuki Yamamoto 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Prefecture Within Sumitomo Metal Industries, Ltd. (72) Inventor Kazuo Okamura 4-5-Kitahama, Chuo-ku, Osaka-shi, Osaka No. 33 Sumitomo Metal Industries Co., Ltd. (72) Inventor Akira Oguri 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshihiko Masuda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F term (reference) 2F051 AA11 AB09 AC01 BA07 BA08 3J101 BA77 FA60 GA22

Claims (3)

[Claims] 1. After a strain gauge is attached to a housing portion where a strain is considered to occur, a static load is applied to a bearing portion to perform a strain measurement, and a measurement point having high sensitivity to the load is selected. A relational expression between load and strain is obtained in advance based on the measurement result at the selected measurement point, then a strain gauge is attached to the selected measurement point and a dynamic load is applied, and measurement is performed with the strain gauge. A method for measuring a load acting on a bearing supporting a rotating body, wherein a load acting on a bearing is obtained from the determined dynamic strain and the relational expression between the load and the strain determined in advance. 2. The load applied to the bearing according to claim 1, wherein a strain gauge is attached to the same position of the housing on both sides of the bearing, and an average of the measured values of the strain gauge is obtained. A method for measuring the load acting on a bearing that supports a rotating body. 3. The measuring method according to claim 1, wherein a measurement is performed on a plurality of units with one step of the rotating body as one unit, and a load acting on the bearing is obtained from an average value of these distortions. Method of measuring the load acting on the bearing that supports the rotating body.