JPH0315136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thrust load measuring device capable of accurately measuring a thrust load acting on a bearing.

[Conventional technology]

For example, in rotating machines such as aircraft engines, gas turbines, and axial flow compressors, thrust loads act on the bearings during operation, but if an abnormality occurs in the bearings due to the thrust loads, it can cause significant damage to the entire rotating machine. It will cause damage. For this reason, conventionally, the thrust load has been estimated and predicted to a certain extent to perform structural design, but it has been difficult to ensure accuracy. Therefore, if the above-mentioned thrust load can be actually measured, it will be advantageous for estimating the life of the bearing, designing the structure, etc., and making economical design possible. However, conventionally there has been no device for measuring the thrust load of the rotating machine.

Therefore, as shown in Japanese Patent Application No. 58-37890, the inventor of the present application loosely fitted the outer ring of the bearing that supports the rotating shaft into the bearing housing, and provided a required number of sensing parts on one side of the bearing. A load converter is disposed, a sensing portion of the load converter is brought into contact with one side of the outer ring of the bearing, and the entire spring constant is the spring constant of the entire load converter sensing portion on the other side of the bearing. A required number of dummy members approximately equal to the number of dummy members are disposed, and the dummy members are brought into contact with the other side of the bearing outer ring, and a required initial tightening force is applied to the sensing portion of the load converter and the dummy member. We have filed an application for a load detector equipped with a device to provide the load at the required location.

The load detector is shown in FIG. 5, and the load converter and dummy members are spring systems a and b, respectively. The initial clamping force applied to the spring systems a and b is P ₀ , the thrust load in the axial direction is F , and the amount of change in the initial clamping force P ₀ generated on the load converter and the dummy member due to the action of the thrust load F is P 0 . Assuming Δf, F+(P ₀ −Δf)=(P ₀ +Δf) is established from the balance of forces, and if we transform and rearrange this, we get F=P ₀ +Δf−P ₀ +Δf=2Δf, so Δf=F/ 2 is obtained.

Similarly, when a thrust load F' acts in the opposite direction to the thrust load F mentioned above, F'+(P ₀ +Δf)=(P ₀ −Δf) F'=P ₀ −Δf−P ₀ −Δf = -2∆f, and therefore ∆f = -F'/2. This equation means that a thrust load in the opposite direction is detected as a thrust load in the opposite direction. In the figure, c is a bearing, d
is an outer ring, e is an inner ring, and f is a rotating shaft.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional device has the following drawbacks.

Thermal output, which is an error component that appears in the output of the load detector due to temperature changes, must be removed by averaging the load detector combinations, but since the thermal output differs depending on the load converter. It cannot be made completely zero, thus reducing measurement accuracy.

The thrust load detected due to the influence of the initial tightening force is 1/2 of the thrust load that actually occurs, and therefore the detected signal is greatly affected by heat output and noise, making it difficult to obtain a signal with good quality. At the same time, accurate measurements cannot be made.

In view of the above circumstances, the present invention has been made with the object of providing a thrust load measuring device for a bearing that is capable of obtaining signals of good quality and measuring with high precision.

[Means for Solving the Problems] The present invention provides a load transducer in which the outer ring of a bearing that supports a rotating shaft is loosely fitted into a bearing housing, and a required number of sensing portions are provided on both sides of the bearing. A sensing part of the load converter is placed in contact with a side surface of the outer ring of the bearing, and a device is provided at a predetermined position to apply a required initial tightening force to the light sensing part of the load converter, and the load converter A differential amplifier is connected to the load converter, which receives signals from the load converter, adds electrical signals of different polarities, and cancels electrical signals of the same polarity.

[Effect]

Therefore, in the present invention, the detected signal is the actual load acting on the thrust bearing, and the detected signal has been freed from the influence of thermal power.

〔Example〕

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

FIG. 1 shows an embodiment of the present invention, in which a bearing housing 2 is fixed to a frame 1 of a required rotating machine,
The outer ring 4 of the bearing 3 is placed in the hollow part of the bearing housing 2.
are loosely fitted so that the bearing 3 can move smoothly in the axial direction, a rotating shaft 6 is rotatably fitted to the inner ring 5 of the bearing 3, and one side of the inner ring 5 is fixed to the rotating shaft 6. The other side of the inner ring 5 is fixed in position by a nut 8 screwed onto the rotating shaft 6 so that the bearing 3 does not slide relative to the rotating shaft 6, and the other side of the inner ring 5 is fixed in position by a nut 8 screwed onto the rotating shaft 6. side wall 9 on one end side of
A ring-shaped chamber 10 is provided, and a unit cell 11, which is a load converter whose top abuts against one side of the outer ring 4, is fitted into the chamber 10. To prevent movement in the circumferential direction, a ring-shaped holder 12 forming a load converter is fitted to the other end of the hollow part of the bearing housing 2, with a spacer (not shown) interposed therebetween, and a ring-shaped holder 12 forming a load converter is fitted to the holder 12. Insert the unit cell 11 into the hole 13.
A unit cell 14 having the same structure as above is inserted, and the side plate 12a is brought into contact with the unit cell 14. An appropriate number of unit cells 11 and 14 are arranged so that their tops abut against the side surface of the outer ring 4, thereby forming a sensing section of the load converter. Also, at one end of the bearing housing 2,
A nut 15 provides initial tightening force to the unit cells 11 and 14 and also serves to prevent the holder 12, etc. from slipping out.
Screw it on. The number of unit cells 11 and 14 may be any number, but when using multiple unit cells,
Make the intervals in the circumferential direction approximately equal. The unit cells 11 and 14 may have the same or different numbers, but it is desirable that the spring constant of the entire unit cell 11 and the spring constant of the entire unit cell 14 be equal. Furthermore, the unit cells 11 and 14 have signal conditioners 21,
22 to the differential amplifier 23, and the signals detected by the unit cells 11 and 14 are connected to the differential amplifier 2
It is now possible to send to 3. Differential amplifier 2
3 has a function of adding electrical signals of different polarities and canceling electrical signals of the same polarity.

Since the unit cells 11 and 14 have the same structure, the details of the load converter including the unit cell 14 will be explained below with reference to FIGS. 2 to 4.
A leg portion 17 is provided on the opposite spherical side of the unit cell 14 whose side that contacts the outer ring 4 of the bearing 3 is spherical so as to transmit the load P applied from the outer ring 4 to the side plate 12a of the holder 12. A recess 18 is provided on both sides, a strain gauge 19 for detecting shear strain is attached to the wall of the recess 18, the recess 18 is filled with heat-resistant and oil-resistant resin, and the unit cell body 16 is covered with stainless steel foil. Protect the strain gauge 19 from heat and oil. Further, on one side of the ring-shaped holder 12 where the unit cell 14 is inserted, the unit cell 1 is inserted.
Notches 20 for taking out lead wires, etc. are provided at approximately the same intervals as the intervals between the legs 17 of 4, and the legs 17,
17 is filled with heat-resistant resin for protection, except for the space for taking out the lead wires.

When detecting the thrust load acting on the bearing 3, set the unit cells 11 and 14 on the rotating machine whose thrust load is to be measured as shown in FIG.
Apply the required initial tightening force to 1 and 14. By applying this initial tightening force, the thrust load is
In the case of F shown in the figure, the thrust load F/2 that increases the initial tightening force is detected on the unit cell 14 side as described above, while the thrust load F/2 that decreases the initial tightening force is detected on the unit cell 11 side. /2 is detected. The thrust load F/2 that increases this initial tightening force is expressed as F/2 in the following explanation, and the thrust load F/2 that decreases the initial tightening force is expressed as -F/2 in the following explanation.

Since the strain gauge on the unit cell 14 side is compressed by the thrust load F/2, the contraction of this strain gauge is set as ε ₁ /2, and the strain gauge on the unit cell 11 side is extended due to the thrust load -F/2, so the extension of this strain gauge is When is set to -ε ₁ /2, the output of the strain gauge in unit cell 14 is ε 1 '=ε 1 /2 + ε _H , taking into account the influence of thermal output, that is, thermal strain ε H, and the output of the strain gauge in unit cell 11 is ε ₁ '=ε ₁ /2+ε _H. The output is -ε ₁ '=-ε ₁ /2+ε _H. Here, the output ε ₁ ' of the strain gauge of the unit cell 14 increases by ε ₁ ' than the output when the initial tightening force is applied, and the output of the strain gauge of the unit cell 11 -
ε ₁ ' means that the output is reduced by ε ₁ ' from the output when the initial tightening force is applied. Therefore, ε ₁ ′ and −
The signal of ε ₁ ' is sent to the signal conditioners 21 and 2.
However, as mentioned above, the differential amplifier 23 has the function of adding electrical signals of different polarities and canceling electrical signals of the same polarity. The output ε of is ε=ε ₁ /2+ε _H +ε ₁ /2−ε _H =ε ₁ .

The output ε thus obtained is sent to a load digital display, an analog recorder, a magnetic recorder, a computer, etc. in the post-processing section, and is subjected to predetermined processing.

Note that the present invention is not limited to the above-described embodiments, and that various shapes of load transducers can be used, and that various changes can be made without departing from the gist of the present invention. Of course, etc.

〔Effect of the invention〕

According to the bearing thrust load measuring device of the present invention, a signal with good quality can be obtained because the thermal output, which is an error component due to temperature change, is removed and the thrust load to be measured is the thrust load that actually occurs. This provides an excellent effect in that the thrust load can be measured with good accuracy.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the bearing thrust load measuring device of the present invention, Figs. 2 to 4 are detailed views of an example of the load converter portion used in the device of Fig. 1, and Fig. 2 is a An explanatory diagram of the partial breakage, FIG. 3 is a view taken in the - direction arrow of FIG. 2, FIG. 4 is a view taken in the - direction arrow of FIG. 2,
FIG. 5 is an explanatory diagram of a conventional bearing thrust load measuring device. In the figure, 2 is a bearing housing, 3 is a bearing, 4 is an outer ring, 5 is an inner ring, 6 is a rotating shaft, 11 and 14 are unit cells, and 23 is a differential amplifier.

Claims (1)

[Claims] 1. The outer ring of the bearing that supports the rotating shaft is loosely fitted into the bearing housing, and a load converter having the required number of sensing parts is arranged on both sides of the bearing, and the sensing part of the load converter is A device is provided at a predetermined position that is brought into contact with the side surface of the outer ring of the bearing and applies a required initial tightening force to the sensing portion of the load converter, and upon receiving the signal from the load converter, adds electrical signals of different polarities. A thrust load measuring device for a bearing, characterized in that a differential amplifier for canceling electric signals of the same polarity is connected to the load converter.