DE1503539B2 - LIQUID SEAL FOR TURBO MACHINERY - Google Patents

Description

The invention relates to a liquid seal for the shaft passage in turbo machines, especially at higher pressures of the working medium, with a barrier fluid filled annular space and one located therein, movable in the radial direction with the shaft Seal body.

It is already known in air and gas compressors to seal the shaft as a liquid seal to train. These are annular sealing bodies, which on their inner circumference Surround the shaft and are guided on both sides in the housing by means of an external approach. By radial The gap between the housing and the sealing body on both sides of the guide attachment is a limited radial displacement of the seal body relative to the housing corresponding to any movements the shaft is basically possible. Such a radial displacement is, however, at high overpressures within the machine difficult or even prevented, because then very large frictional resistance on the from Internal pressure axially loaded guide surface must be overcome. The consequence of this are through shear stress occurring damage to the seal body.

In contrast, it is the object of the invention to provide a liquid seal by making it the shear stress of such a seal is eliminated and the internal overpressure of the Machine can be of any size.

This object is achieved in that on the outside of the space the Lateral guide surface of the sealing body opposite, which is loaded by the axial internal pressure of the machine the housing or an annular body firmly connected to the housing only have approximately the same diameter as the shaft has in the area of the seal, the shaft having a shoulder with a slightly smaller diameter on the axially loaded guide surface has, and that on the inside of the gap, the sealing body on its end face as well a guide surface opposite the housing or an annular body firmly connected to the housing with only a slightly larger diameter than the shaft, and which is under the pressure of the barrier fluid standing space extends here as well up to the guide surfaces of the sealing body.

Another advantage of the invention is that as a result of the elimination of the shear stress Sealing body is made in a known manner from a non-metallic material.

An embodiment of the invention is shown in the drawings and will be described in more detail below explained. It shows

F i g. 1 a previously common design of a sealing body in a turbo compressor and

F i g. 2 shows an embodiment according to the invention.

F i g. 1 shows the conventional design for a turbo compressor, the shaft 1 of which is surrounded at the outlet from the housing 2 by an annular sealing body 3 which is inserted into a housing cover 4 on the end face with little radial play s. The likewise annular guide extension 3 'on the outer circumference of the sealing body protrudes into a recess 5 of the housing cover, which is also provided with a bore 6 for the supply of the sealing liquid. Also in the sealing body 3, preferably at the same circumferential point, there is an essentially radial bore 7 for forwarding the sealing fluid into an annular space 8 which directly surrounds the shaft 1 and is axially delimited on both sides by the bearing metal layer 9 of the sealing body 3.

The pressure prevailing inside the housing 2 of the compressor now exerts on the sealing body 3 in the direction of the arrow exerts an axial force on the seal body, which results in shear stress of management approach 3 and results from the following relationship:

- P ₁

· Π

d ₂ ² π

■ -, (D

where P ₁ = internal overpressure of the machine

in atü,
d ₁ = mean diameter of the sides

area of the guide approach 3 ',
d ₂ - diameter of the shaft 1.

In order to overcome this axial force K _a in the event of a radial displacement of the shaft, a radial force K _{r is} required, which results from the following relationship:

K _r = P ₂ - b d ₂ , (2)

where P ₂ = the permissible specific surface pressure on the shaft,
b = the axial length of the seal,
b · d ₂ = the plane projection of the entire sealing surface.

From the above equations, taking into account also the coefficient of friction and possibly the weight of the sealing body 3, it can no longer be displaced in practically multiple levels _{with such a construction and an internal overpressure P 1.}

F i g. In contrast, 2 shows an embodiment according to the invention. In this case, the sealing body 10 has a shoulder 10 'at the outside end, which surrounds a shaft shoulder 1' with the same radial distance ί with a slightly smaller diameter compared to the sealing diameter d _2. The mean diameter d ₃ with which this shoulder 10 ′ rests laterally against an annular body 11 firmly inserted in the housing cover 4 corresponds approximately to the seal diameter d ₂ . In this way, in accordance with the above equation 1 ( if d _{3 is} substituted for J ₁ ), the internal overpressure P _{1 of} the machine can be practically infinitely large without it exerting an axial shear stress on the sealing body 10. Thus, there is practically no resistance to radial displacement of the sealing body 10 in the event of shaft displacements.

In this new embodiment, it is also essential that the sealing body 10 is also surrounded on its opposite end face facing the interior of the machine (on the right in FIG. 2) by the ring body 11 up to close to the sealing diameter d _{2 of} the shaft 1. In addition, the between

the annular body 11 and the sealing body 10 lying interior 12, in which an internal pressure The liquid pressure slightly exceeding the machine prevails on both end faces of the sealing body 10 up to its guide surfaces which are close to the shaft 1 or the shaft shoulder 1 ″.

As a safeguard against rotation of the sealing body 10 is used in a known manner in the Ring body 11 inserted pin 13.

For opposite or reciprocal overpressures, e.g. B. relaxation turbines, the Sealing body 10, the ring body 11 and the shaft 1 also at the inner end of the seal within the meaning of the invention form.

Claims (2)

Patent claims: 1. Liquid seal for the shaft feedthrough in turbo machines, especially in higher pressures of the working medium, with an annular space filled with a barrier fluid and a seal located therein, movable in the radial direction with the shaft body, characterized in that on the outside of the intermediate space (12) the Lateral guide surface of the sealing body (10) with respect to the housing (2) or a with the housing firmly connected ring body (11) only about the same diameter as the shaft (1) in the area of the seal, with the shaft (1) resting on the axially loaded guide surface (10 ') a shoulder (1 ') with a slightly smaller diameter, and that on the inside of the space (12) the sealing body (10) also has a guide surface opposite on its end face the housing (2) or an annular body (11) fixedly connected to the housing with only has a little larger diameter than the shaft (1) and that is under the pressure of the barrier fluid standing space extends here as well up to the guide surfaces of the sealing body. 2. Liquid seal according to claim 1, characterized in that the sealing body (10) is made in a manner known per se from a non-metallic material. 1 sheet of drawings