JP3039004B2 - Bearing thrust load measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and lightweight thrust load measuring device for accurately measuring a thrust load acting on a bearing.

[0002]

2. Description of the Related Art When an excessive thrust load acts on a bearing portion of a rotating machine such as an aircraft engine, a gas turbine or an axial compressor, the bearing not only damages the bearing but also affects the entire machine. For this reason, this thrust load is measured,
By taking measures in accordance with the values, accident prevention and safety can be improved.

Therefore, various devices for measuring a thrust load have been studied.

FIGS. 3 to 11 show a conventional thrust load measuring device. An inner race 3 of a bearing 2 is fitted on a rotatable shaft 1 so as to be able to rotate integrally with the shaft 1. Is fitted with an outer race 5 via a ball 4, and a flange 6 is fixed to the outer periphery of the outer race 5. The inner race 3 is fastened by a fastening nut 7 and is fixed to the shaft 1.

On both sides of the flange 6 of the bearing 2, an annular bearing support member 8 and a bearing support member 9 having a hollow cylindrical side plate 9a on the flange 6 side are arranged.
Are opposed to each other in a nested manner, and a slight gap G is maintained on the facing surface between the flange 6 and the side plate 9a of the bearing support member 8 and the bearing support member 9. The bearing support member 8, the flange 6, and the side plates 9a of the bearing support member 9 are fastened by bolts 10 which are also provided at substantially equal intervals in the circumferential direction and serve also as rotation stoppers.

In the recesses provided at substantially equal intervals in the circumferential direction of the bearing support member 8, unit cells 11 for measuring the thrust load are provided.
The top of the unit cell 11 is in contact with one side surface of the flange 6, and a unit cell 12 for measuring a thrust load is provided in a recess provided at substantially equal intervals in the circumferential direction of the bearing support member 9. The unit cell 12 is disposed so as to face the unit cell 11, and the top of the unit cell 12 is in contact with the other side surface of the flange 6. And a tightening bolt 14 screwed with the initial tightening member 13 to the side plate 9a.
By pressing, the unit cells 11 and 12 can be preloaded.

Further, as shown in FIG. 8, the unit cells 11 and 12 are connected to a differential amplifier 22 through signal conditioners 20 and 21, and the unit cells 11 and 12 are connected to each other.
Can be transmitted to the differential amplifier 22. The differential amplifier 22 has a function of adding electric signals having different polarities and canceling out electric signals having the same polarity.

Since the unit cells 11 and 12 have the same structure, the unit cell 11 will now be described in detail with reference to FIGS. 9 and 10. The side of the bearing 2 that contacts the flange 6 fixed to the outer race 5 will be described. Legs 16 are provided on the anti-spherical surface side of the spherical unit cell main body 15 so that a thrust load F applied from the flange 6 can be transmitted to the bearing support member 8. A strain gauge 18 for detecting shear strain is attached to the bottom surface and the ceiling surface of the concave portion 17, and a heat-resistant and oil-resistant resin is filled from above, and the unit cell body 15 itself is made of stainless steel foil. Coated, the strain gauge 18 is protected from heat and oil. A notch 19 for taking out a lead wire or the like is provided at substantially the same interval as the interval between the legs 16 of the unit cell 11 at the center side of the shaft 1 at the unit cell 11 fitting portion of the bearing support member 8. Part 1
The space between 6 and 16 is filled with a heat-resistant resin for protection except for the space for taking out the lead wire.

The thrust load is transmitted along the path of shaft 1 → bearing 2 → flange 6 → unit cell 11 or 12 → bearing support member 8,9 or 9,8, and in the process, a unit cell having load-electric conversion capability The signals are converted into electric signals by 11 and 12 and recorded and displayed. When the thrust load acting on the bearing 2 is detected, the unit cell 1 as shown in FIG.
1 and 12 are set, and the tightening bolt 14 is rotated to apply a required initial tightening force to the unit cells 11 and 12.

Then, in the force balance model of FIG. 11 schematically showing FIG. 4, the initial tightening force is P ₀ , the axial thrust load is F, and the thrust load F is applied to the unit cells 11 and 12 by the action of the thrust load F. Assuming that the amount of change in the initial tightening force P ₀ is Δf, F + (P ₀ −Δf) = (P ₀ +
Δf) holds, and when this is changed and rearranged, F = P ₀ + Δf−P ₀ + Δf = 2Δf, and Δf = F / 2 is obtained.

Therefore, on the unit cell 11 side, a thrust load F / 2 for increasing the initial tightening force P ₀ is detected,
On the other hand, on the unit cell 12 side, a thrust load F / 2 for reducing the initial tightening force P ₀ is detected. This initial tightening force P
_The thrust load F / 2 that increases ₀ is F in the following description.
/ 2 represents, in the initial tightening force thrust load F / 2 to reduce the P ₀ the following description represented by -F / 2.

[0012] Also, since the strain gauge 18 of the unit cell 11 side by the thrust load F / 2 is compressed, the contraction of the strain gauge 18 and epsilon _1/2, the thrust load -F / 2 of the unit cell 12 side Since the strain gauge 18 extends,
With the extension of the strain gauges 18 and-epsilon _1/2, in consideration of the influence i.e. thermal strain epsilon _H heat output, the unit cell 11
The output of strain gauge 18 is _{ε 1 '= ε 1/2} + ε H, the output of the strain gauge 18 of the unit cell 12 in -
epsilon ₁ 'is _{= -ε 1/2 + ε H} .

Here, the output ε ₁ ′ of the strain gauge 18 of the unit cell 11 increases by ε ₁ ′ from the output when the initial tightening force P ₀ is applied, and the strain gauge 18 of the unit cell 12 Means that the output −ε ₁ ′ is reduced by ε ₁ ′ from the output when the initial tightening force P ₀ is applied.

Thus, the signals of ε ₁ ′ and −ε ₁ ′ pass through the signal conditioners 20 and 21 to the differential amplifier 22.
Although sent to the differential amplifier 22 adds a polarity different electrical signals, because of a function of canceling the same electrical signal polarity, the output epsilon of the differential amplifier _{ε = ε 1/2 + ε} H + ε 1 / 2−ε _H = ε ₁ and the influence of the thermal strain ε _H is removed.

The output ε thus obtained is used as a load digital display, an analog recorder, a magnetic recorder,
Alternatively, the data is sent to a computer or the like, and predetermined processing is performed.

The tangential force due to the swirling torque accompanying the rotation of the shaft 1 is supported by the bolt 10.

According to the bearing thrust load measuring device described above, the thrust load is immersed in high-temperature oil, vibrated,
Unit cell 1 regardless of the repetition force of sudden release
Since it is quickly and reliably transmitted to the first and the second, the load can be accurately detected.

Further, since the unit cells 11 and 12 are mounted on the bearing support members 8 and 9, the entire apparatus becomes small and lightweight.

Furthermore, the bearing 2 can be brought into a normal state in the assembling stage so that an abnormal load is not applied to the bearing 2, and the safety of the device can be improved.

The bearing 2 is prevented from being damaged, the burden on other mechanical parts is reduced, and the stability around the bearing 2 enables early detection of other abnormalities.

The load converting member to which the strain gauge 18 is attached can be used repeatedly, and is interchangeable, so that the manufacturability is good.

Since the entire apparatus can be handled as one unit, it is possible to easily inspect a failed part and replace the load converting member.

[0023]

However, the conventional bearing thrust load measuring device has the following problems.

That is, when an initial tightening force is applied to the unit cells 11 and 12, an initial tightening load determined by design must be applied by the tightening bolt 14 via the bearing support members 8 and 9. In this case, the initial tightening load acts directly on the unit cells 11 and 12, so that an appropriate initial tightening force determined by design is applied to the unit cells 11, 12.
Not only is it difficult to apply to the unit cells 12, but if the initial tightening force is too large, the rated loads of the unit cells 11, 12 that can be used are also limited.

Further, the unit cell 1 having a large rated load
If the thrust loads to be measured are smaller than the rated loads of the unit cells 11 and 12 when using the cells 1 and 12, the measurement accuracy is reduced.

Further, the flange 6 is fixed by the tightening bolt 14.
When a supporting load determined by design is applied to the bearings and the bearing support members 8 and 9, the bearing support members 8 and 9 may be deformed to make it difficult to perform accurate measurement.

In view of the above-mentioned circumstances, the present invention can set the rated output of the unit cell without being affected by a design-dependent supporting load to be applied to the bearing support member, and can measure the deformation by deformation of the bearing support member. It is an object of the present invention to provide a bearing thrust load measuring device capable of preventing a decrease in accuracy.

[0028]

According to the present invention, bearing support members are provided on both side surfaces of a flange fixed to the outer periphery of a bearing outer race, and strain gauges are provided on each bearing support member at substantially equal intervals in a circumferential direction. A unit cell holder for holding a unit cell having a top portion abutting on the side surface of the flange is provided, and a corresponding unit cell holder of each bearing support member is fastened with a tightening bolt penetrating the flange, and a tightening bolt of the flange is penetrated. An initial tightening force adjuster whose length is adjusted so that a predetermined initial tightening force is applied to the unit cell when the unit cell holder comes into contact with both ends while both ends slightly protrude from the bolt hole at both ends thereof. The present invention relates to an apparatus for measuring a thrust load of a bearing, wherein the thrust load is fitted.

[0029]

When the unit cell holder is tightened with the tightening bolt, the unit cell holder is given a unit cell supporting load determined by design.

At this time, since the initial tightening force adjuster is interposed between the unit cell holders, a desired initial tightening force acts on the unit cell when the unit cell holder comes into contact with the initial tightening force adjuster. The initial tightening force of the unit cell does not change even if the tightening bolt is further tightened.
Therefore, the initial tightening force can be applied to the unit cell regardless of the support load of the unit cell.

[0031]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIGS. 3 to 11 represent the same components.

A unit cell holder 24 for holding the unit cell 11 is movably fitted toward the flange 6 in the recess 23 of the bearing support member 8, and the side plate 9 of the bearing support member 9 is provided.
A unit cell holder 26 holding the unit cell 12 is movably fitted into the recess 25 of FIG. The head 27 is locked inside the unit cell holder 24, and the body 28 is connected to the unit cell holder 24, the flange 6,
A tightening bolt 30 is provided in which the male screw portion 29 penetrates through the unit cell holder 26 and the side plate 9 a and protrudes toward the side opposite to the flange 6 of the side plate 9 a.

The unit cell holders 24, 26 are provided at both ends in a state where the tightening force adjusting nut 31 is not screwed into the bolt hole 32 through which the tightening bolt 30 of the flange 6 passes.
An initial tightening force adjuster 33 made of a collar ring having a length protruding into the gap G so as not to contact with the fitting is fitted. The initial tightening force adjuster 33 has unit cell holders 24, 2 at both ends.
The length is set so that a desired initial tightening force is applied to the unit cells 11 and 12 when the unit cell 6 comes into contact with the unit cell.

Next, the operation will be described.

In order to apply the initial tightening force to the unit cells 11 and 12, first, an initial tightening force adjuster 33 having a length to be described later is used.
Is set in the bolt hole 32 of the flange 6.

When the tightening force adjusting nut 31 is tightened, the tightening bolt 30 and the tightening bolt 30
The unit cell holder 24 locked to the unit 7 is pulled toward the flange 6, and the unit cell holder 26 on the tightening force adjusting nut 31 is also pushed toward the flange 6 by the tightening force adjusting nut 31.

When the unit cell holders 24 and 26 move toward the flange 6 and come into contact with the initial tightening force adjuster 33, even if the tightening force adjusting nut 31 is tightened, the unit cell holder 2
4 and 26 cannot move to the flange 6 side any more.

As described above, the unit cell holders 24, 2
6 comes into contact with the initial tightening force adjuster 33 and the flange 6
When it becomes impossible to move to the side, the unit cell 1
A predetermined tightening force acts on 1 and 12.

Thus, the unit cell holders 24, 26
When the tightening force adjusting nut 31 is continuously tightened after it becomes impossible to move to the flange 6 side, the unit cell holder 2
Since a compressive force acts on each of the unit cell holders 24 and 26, the tightening force adjusting nut 31 is tightened.
Can be given a supporting load of the unit cells 11 and 12 determined by design.

Moreover, even after a design supporting load is applied to the unit cell holders 24, 26, the unit cell holders 24, 26 abut against the initial tightening force adjuster 33 and are kept in a state where they cannot move any more. Therefore, the tightening force acting on the unit cells 11 and 12 does not change from the predetermined value.

Accordingly, when the unit cell holders 24, 26 abut against the initial tightening force adjuster 33 and cannot move any more, the tightening force applied to the unit cells 11, 12 becomes the initial tightening force. The initial tightening force is determined according to the length of the initial tightening force adjuster 33.

In addition, the initial tightening force applied to the unit cells 11 and 12 is the same as the unit cells 11 and 12 determined by design.
It is accurately determined irrespective of the supporting load.

Further, since the initial tightening force adjuster 33 is provided to restrict the movement of the unit cell holders 24, 26, when the unit cell holders 24, 26 are applied with a designed supporting load, the unit cell holders 24, 26 can be used. 24,26
Is prevented from being deformed, and the unit cell holder 24,
A decrease in measurement accuracy due to the deformation of 26 is prevented.

Further, since the initial tightening force adjuster 33 is provided between the unit cell holders 24 and 26, even if the unit cells 11 and 12 are damaged, the flange 6 can be used.
Is restricted in the longitudinal direction of the shaft 1, and a fail-safe function can be achieved.

Moreover, according to the present invention, a plurality of initial tightening force adjusters 33 having different lengths are prepared, and are appropriately selected and used according to the purpose, so that any initial tightening force can be applied to the unit cells 11 and 12. It is possible to use the unit cells 11 and 12 whose rated output is the optimum value according to the thrust load to be measured,
Measurement accuracy can be improved.

FIG. 2 shows a force balance model schematically illustrating the present invention. In the figure, F is the axial thrust load, Δf ₁ is the amount of change in the initial tightening force generated in the unit cell 11, and Δf _2.
Is a change amount of the initial tightening force generated in the unit cell 12, K is a spring coefficient of a system in which the tightening bolt 30 and the initial tightening force adjuster 33 are integrated, _Ku is a spring constant of the unit cells 11 and 12, δ ₁ Is the displacement of the flange 6 caused by the thrust load F, and δ ₂ is the displacement of the unit cell holder 24 caused by the thrust load F.

From the balance of force and the displacement of each spring system, F = Δf ₁ + Δf ₂ − (1) Δf ₂ = δ _{2 Ku} − (2) Δf ₁ = (δ ₂ −δ ₁ ) K _u − (3 Δf ₁ = δ ₁ K− (4) holds, and the equation (5) obtained by modifying the equation (4) is substituted into the equation δ ₁ = Δf ₁ / K− (5) (3) to obtain the equation (6). and _{then, Δf 1 = (δ 2 -Δf} 1 / K) K u - (6) (6) was organized expression (7) below the _{δ 2 K u = (1 +} K u / K) Δf 1 - (7) ( Substituting equation (2) into equation (8), Δf ₂ = δ _{2 Ku} = (1 + K _u / K) Δf _1- (8) Substituting equation (8) into equation (1), equation (9) F = Δf ₁ + (1 + K _u / K) Δf ₁ = ｛(2K + K _u ) / K｝ Δf _1- (9) When the expression (9) is summarized with respect to Δf ₁ , the expression (10) is obtained. Δf ₁ = ｛K / (2K + K _u )｝ F− (10) Further, the expression (11) obtained by modifying the expression (8) is replaced by Δf ₁ = ｛K / (K + K _u )｝ Δf _2- (11) (10) and rearranging into equation, {K / (K + K u)} Δf 2 = {K / (2K + K u)} F Δf 2 = {(K + K u) / (2K + K u)} F - (12) (12) An expression is obtained.

[0049] Depending, (11), bolts 30 tightening the spring constant K _u of the unit cells 11 and 12 from (12)
When the initial tightening force adjustment member 33 can be sufficiently smaller than the spring constant K of the system to be integrated and, Delta] f ₁ and Delta] f ₂ 1 /
It is understood that high measurement accuracy can be obtained, which is close to 2F.

The thrust load measuring device for a bearing of the present invention is not limited to the above-described embodiment, but is particularly effective when measuring the thrust load of a bearing having a large outer diameter. It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0051]

As described above, according to the bearing thrust load measuring device of the present invention, the following various excellent effects can be obtained.

The initial tightening force is provided by the provision of the adjusting tool.
The initial tightening force can be set for the unit cell separately from the support load of the unit cell determined by design, and the initial tightening force can be accurately applied.

Further, since the initial tightening force of the unit cell can be set separately from the supporting load of the unit cell determined by design, the initial tightening force of the unit cell can be reduced with respect to the thrust load for which the rated load of the unit cell is to be measured. The measurement accuracy can be improved by setting the optimum value.

Since the unit cell holder is prevented from being deformed by the initial tightening force adjuster, the measurement accuracy is prevented from lowering.

Since the initial tightening force adjuster is provided, even if the unit cell is broken, the bearing can be prevented from moving in the axial direction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a force balance model schematically showing FIG. 1;

FIG. 3 is a partial front view showing a set position of a conventional thrust load measuring device for a bearing.

4 is a view in the direction of arrows IV-IV in FIG. 3;

FIG. 5 is a view in the direction of arrows VV in FIG. 3;

6 is a view taken in the direction of arrows VI-VI in FIG. 4;

FIG. 7 is a view in the direction of arrows VII-VII in FIG. 4;

FIG. 8 is a conventional control system diagram.

FIG. 9 is a detailed view of a unit cell used in a conventional thrust load measuring device for a bearing.

FIG. 10 is a partially cutaway plan view of FIG. 9;

FIG. 11 is a force balance model schematically showing FIG. 4;

[Explanation of symbols]

 2 Bearing 5 Outer race 6 Flange 8,9 Bearing support member 11,12 Unit cell 18 Strain gauge 24,26 Unit cell holder 30 Tightening bolt 32 Bolt hole 33 Initial tightening force adjuster

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-208553 (JP, A) JP-A-59-79828 (JP, A) Jpn. Field (Int.Cl. ⁷ , DB name) G01M 13/00-13/04

Claims (1)

(57) [Claims] 1. A bearing support member is disposed on both sides of a flange fixed to the outer periphery of a bearing outer race, and each bearing support member is provided with strain gauges at substantially equal intervals in a circumferential direction, and a top portion is provided on a side surface of the flange. A unit cell holder for holding the contacting unit cell is provided, and the corresponding unit cell holder of each bearing support member is fastened with a tightening bolt penetrating the flange. An initial tightening force adjuster whose length is adjusted so as to project slightly and to apply a predetermined initial tightening force to the unit cell when the unit cell holder comes into contact with both ends is fitted. Thrust load measuring device for bearings.