JPH0624613Y2 - mechanical seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mechanical seal applied to a shaft sealing device of a high-speed rotating machine.

[Conventional technology]

 An example of a conventional mechanical seal is shown in FIGS.

In FIG. 3, 1 is a rotary shaft, 2 is a casing, 3 is a rotary ring, 4 is a rotary holding metal fitting, 5 is a seal ring, 6 is a seal casing, 7 is a spring for pressing the seal ring against the rotary ring, and 8 is O. A ring, A is a high pressure chamber, and B is a low pressure chamber. In this type of mechanical seal, in order to prevent the fluid in the high pressure chamber A from leaking to the low pressure chamber B, the seal ring 5 is subjected to the fluid pressure acting on the ring and the pressing force of the spring 7 applied to the ring. Therefore, the structure is such that it is pressed against the rotary ring 3.

FIG. 4 shows another type of mechanical seal. 9 is a high pressure fluid supply hole provided on the circumference of the seal ring,
The other parts are the same as in FIG. The high pressure fluid supply hole 9 is
In order to operate the rotary ring 3 and the seal ring 5 with a small distance in the axial direction, the fluid static pressure of the high-pressure chamber A is introduced to the axial clearance between the rotary ring 3 and the seal ring 5. Is.

FIG. 5 shows another type of mechanical seal. 1
Reference numeral 0 denotes a spiral groove provided on the surface of the rotary ring 3 facing the seal ring 5, and other portions are the same as those in FIG. As in the case of FIG. 4, the spiral groove 10 is operated by holding the minute clearance in the axial direction between the rotary ring 3 and the seal ring 5 and operating the shaft 1 in the minute clearance by the rotation of the shaft 1. It is provided in such a shape that a mechanical fluid pressure is applied.

In short, in the example of FIG. 3, the rotary ring and the seal ring are always in contact with each other, and in the examples of FIGS. 4 and 5, the static force or power generated in the axial clearance formed by the both It operates with a small clearance maintained by a mechanical force.

[Problems to be solved by the device]

Three types of examples of the conventional technology are shown, but each of them has the following problems.

In the example of FIG. 3, since the seal ring 5 and the rotary ring 3 are in contact with each other, the seal ring 5 is worn due to long-term operation,
The sliding surface of the seal ring becomes rough, and in extreme cases, burnout occurs.

In the example of FIG. 4, the seal clearance that operates uniquely due to the balance of the fluid pressure acting on the seal ring in the axial direction causes a clearance. Therefore, the operating pressure conditions differ from the initial design conditions and the operating pressure changes during operation. On the other hand, it is difficult to always maintain an optimum operating state without an abnormal increase in the amount of leakage and wear of the seal ring.

In the example of FIG. 5, the seal clearance is uniquely determined by the balance between the axial force of the fluid pressure acting on the seal ring and the fluid pressure generated in the seal clearance due to the shaft rotation. For this reason, under conditions below the design speed such as when starting or stopping, sufficient fluid dynamic pressure does not occur in the seal clearance, causing contact between the seal ring and rotating ring, and causing surface roughness of the seal ring In some cases, burnout occurs.

In short, in any case, it could not be used in a stable state for a long time.

That is, when the pressing force between the rotary ring and the seal ring is too large, the seal ring may be worn or the sliding surface may be roughened to cause burnout. If the seal ring and the seal ring tend to separate from each other, the amount of leakage increases, which is not preferable.

The present invention is intended to provide a mechanical seal that does not cause wear or burnout of the seal ring or an abnormal increase in the amount of leakage even when used for a long period of time or when operating conditions are changed. .

[Means for Solving the Problems]

The present invention has solved the above-mentioned problems, and includes a rotary ring provided on a rotary shaft, the rotary ring having a sliding surface perpendicular to the rotary shaft on a surface opposite to the high pressure chamber, and a sliding surface facing the sliding surface. A seal ring having an intermediate chamber that is fitted into the seal ring from the low-pressure chamber side and has a fluid sealed between the seal ring and the seal ring. A seal ring retainer that can be moved in the axial direction by being combined with the same seal ring and integrated with the same seal ring.
A spring that pushes the seal ring retainer toward the high pressure chamber, a piston that is installed in the seal ring retainer and moves in and out of the intermediate chamber by an electric drive device, a power supply that supplies current to the drive device, and the temperature of the seal ring is measured. A thermometer, a flow meter that measures the amount of leakage of fluid that leaks from the clearance of the sliding surface, and a current value supplied from the power source to the drive device of the piston according to the temperature of the seal ring and the amount of leakage. The present invention relates to a mechanical seal having a control device for controlling.

[Action]

In the mechanical seal of the present invention, the seal ring and the seal ring retainer are coupled to each other on the side closer to or farther from the intermediate chamber in the radial direction when viewed from the position of the rotating shaft. Since the mutual displacement is possible on the side where the coupling is not performed, the seal ring retainer is slightly deformed toward the intermediate chamber when pressed against the rotary ring. The degree of this deformation is controlled by changing the internal pressure of the intermediate chamber by changing the insertion amount of the piston into the intermediate chamber. When the piston is inserted deeply, the deformation becomes small, and as a result, the pressing force becomes large, so the amount of leakage decreases but seal ring wear and burnout occur, which is not preferable. When the piston is inserted shallowly, the deformation becomes large,
Since the pressing force is small, wear and burning do not occur, but the amount of leakage increases, which is not preferable. The former state can be detected by measuring the temperature of the seal ring, and the latter state can be detected by measuring the leakage amount. In the present invention, the values of the seal ring temperature and the amount of leakage are properly verified in advance and the pressing force is changed by controlling the piston drive current during operation so that the temperature and the amount of leakage do not deviate from the verified values. Such holding prevents wear, burnout, and increase in leakage.

〔Example〕

FIG. 1 shows a sectional view of an embodiment of the present invention. In the figure, 11 is an intermediate chamber on a ring filled with oil, 12 is an electromagnetically driven piston, 13 is a thermometer such as a thermocouple for measuring the temperature of the seal ring 5, and 14 is a flow meter for measuring the amount of leakage. Reference numeral 15 is a power source for supplying a current to an electromagnetically driven piston. 16 is a seal ring retainer fitted to the seal ring 5 so as to form an intermediate chamber 11 between the low pressure chamber side and the seal ring 5. 17 is a seal. A bolt that connects the ring 5 and the seal ring retainer 16 together. In this figure, the parts denoted by reference numerals 1 to 8 have the same structure and function as those of the prior art shown in FIG.

The seal ring 5 is pressed against the rotary ring 3 by the force of the spring 7 with the pressure of the high pressure chamber A. The pressing force is large,
If the seal ring and the rotary ring are in too much contact with each other, the amount of leakage is small, which is convenient, but problems such as increased wear and burnout occur. Whether or not it is in this state can be detected by the degree of temperature rise of the seal ring measured by the thermometer 13. Further, when the pressing force is small and the seal ring and the rotary ring tend to separate from each other, wear and burning do not occur, but the amount of leakage increases, which is not preferable. Whether or not it is in this state can be detected by the degree of increase in the amount of leakage measured by the flow meter 14. Therefore, the values of the seal ring temperature and the amount of leakage in an appropriate operating state are previously verified, and when the temperature or the amount of leakage of the seal ring tends to be larger than the above-mentioned verified value during operation, those values are By controlling the pressing force so as to reduce the value, the pressing force is properly maintained.

In the present embodiment, the pressing force is controlled by changing the insertion amount of the electromagnetically driven piston 12 inserted into the intermediate chamber 11. If the seal ring 5 is extremely drawn, it is bent and deformed as shown by the dotted line in FIG. Piston 12
When the seal ring 5 is deeply inserted into the intermediate chamber 11, the internal pressure of the intermediate chamber 11 increases, the degree of deformation of the seal ring 5 decreases, and the pressing force against the rotary ring 3 increases. On the contrary, when the piston 12 is shallowly inserted into the intermediate chamber 11, the pressing force is small.

The piston insertion power can be changed by changing the piston drive power source 1
This is done by changing the value of the current supplied to the No. 5 circuit. When the current value supplied to the piston is increased, the piston insertion amount is increased and the pressing force is increased as described above. Conversely, if the current value is made smaller, the pressing force becomes smaller.

The control of the current value is performed by a control device (not shown) so that the temperature of the seal ring and the amount of leakage keep the above-mentioned verification value. When the temperature of the seal ring becomes higher than the certified value, the current value is controlled so as to reduce the pressing force. On the contrary, when the leakage amount becomes higher than the verification value, the current value is controlled so as to increase the pressing force.

As described above in detail, in the mechanical seal of the present embodiment, the current value is controlled to change the pressing force so that the temperature and the amount of leakage of the seal ring are maintained at the values in the proper operating state. Therefore, even if the seal ring is used for a long period of time or the operating conditions are changed, the seal ring is not worn or burned, and the leakage amount does not increase abnormally.

In the above embodiment, the gist of the present invention is applied to the contact type seal shown in FIG. 3, but the present invention is also applicable to the non-contact type seal shown in FIGS. 4 and 5. Further, in the above embodiment, the seal ring 5 and the seal ring retainer 16 are coupled on the side closer to the intermediate chamber than the rotary shaft, but may be coupled on the far side. Further, although the flow meter 14 is provided on the high pressure chamber side in the above embodiment, it may be provided on the low pressure chamber side. Further, in the above embodiment, the electromagnetic force is used to drive the piston, but the same effect can be obtained by using the piezo effect.

[Effect of device]

In the mechanical seal of the present invention, the supply current value is controlled to change the insertion amount of the electrically driven piston into the intermediate chamber, and thereby the pressing force of the seal ring against the rotary ring is adjusted. Since the temperature and the leakage amount of the seal ring are maintained at the values in the proper operating state, the seal ring is not worn or burned, and the leakage amount does not increase abnormally. Therefore, the seal ring of the present invention can maintain an appropriate operating condition even when it is used for a long period of time or when operating conditions are changed.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a modification explanatory view of the seal ring shown in FIG. 1, and FIGS. 3, 4, and 5 are sectional views of a prior art. . DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Casing, 3 ... Rotating ring, 4 ... Rotating ring holding metal fittings, 5 ... Seal ring, 6 ... Seal casing,
7 ... Spring, 8 ... O-ring, 9 ... High pressure fluid supply hole, 10 ...
Spiral groove, 11 ... intermediate chamber, 12 ... electromagnetically driven piston,
13 ... Thermometer, 14 ... Flowmeter, 15 ... Power supply, 16 ... Seal ring retainer, 17 ... Bolt

 ─────────────────────────────────────────────────── ───Continued from the front page (56) References JP-A-1-242876 (JP, A) Actual Development Sho-58-42455 (JP, U) JP-B 47-39378 (JP, B1)

Claims (1)

[Scope of utility model registration request] 1. A rotary ring provided on a rotary shaft, the rotary ring having a sliding surface perpendicular to the rotary shaft on a surface opposite to the high pressure chamber, a seal ring having a sliding surface facing the sliding surface, and the seal ring. An intermediate chamber in which fluid is enclosed is formed between the low pressure chamber side and the same seal ring, and the intermediate ring chamber is connected to the seal ring either on the side closer to the rotary chamber or on the side farther from the intermediate chamber. A seal ring retainer that is movable in the axial direction integrally with the seal ring, a spring that pushes the seal ring retainer toward the high pressure chamber, and a piston that is provided in the seal ring retainer and moves into and out of the intermediate chamber by an electric drive device, A power supply for supplying a current to the drive unit, a thermometer for measuring the temperature of the seal ring, a flow meter for measuring the amount of fluid leaking from the clearance of the sliding surface, and the temperature and the leakage of the seal ring. Mechanical seal being characterized in that a control device for controlling a current value supplied to the drive of the piston from the power supply in accordance with the amount.