JPS6139486B2 - - Google Patents

Description

Detailed Description of the Invention (Field and Object of the Invention) The present invention relates to a rotary fluid machine that uses a two-phase fluid as a working fluid. The present invention relates to an improvement in a side seal device provided in a gap between axially opposing surfaces of two rotating bodies that rotate relative to each other to prevent leakage of the working fluid.

(Background Art) Generally speaking, in order to prevent leakage of working fluid in the gap formed between the axially opposing surfaces of two rotating bodies that rotate relatively, the gap should be kept at the minimum allowable gap. However, in consideration of the fact that vibrations and thermal expansion differences inevitably occur in the machine, the actual situation is that this gap is usually made quite large with some allowance.

However, if such a gap is not provided with any sealing device, when this gap becomes large, the amount of working fluid leaking will increase accordingly.
For example, in a rotary engine, there are various disadvantages and inconveniences such as a decrease in output, so a side seal device is provided between opposing surfaces. By the way, due to its nature, this type of side seal, which is provided on the opposing surface of one of the rotating bodies, is placed so that it can be displaced within a certain range in the axial direction, and is sensitive to vibrations, thermal expansion differences, etc. of the rotating body. It must be possible to maintain as small a gap as possible while still handling the problem.

(Objects and Structure of the Invention) The present invention has been made in order to solve and eliminate the disadvantages in properties and inconveniences in use that have been observed in conventionally known side seal devices of this type. By always maintaining the gap formed between the sliding surface of the side seal and the opposing surface of the rotating body at a preset desired minimum value,
It is an object of the present invention to provide a side seal device for a rotary fluid machine in which the amount of leakage of working fluid from the gap is reduced to substantially zero. Therefore, in the side seal device for a rotary fluid machine according to the present invention, the axially opposing opposing surfaces of two rotating bodies that rotate relative to each other around two different rotating shafts, at least one of which is immobile, The side seal provided in between is one of the rotating bodies (hereinafter referred to as the rotating body).
The rotor is loosely fitted into a groove carved in the opposing surface of the rotating body so as to be freely displaceable within a certain range in the axial direction, and a sealing liquid supply passage passing through the rotating body is connected to the groove. A recess is provided on the sliding surface side of the side seal, the pressure of the sealing liquid in the liquid supply path acts on the end surface opposite to the sliding surface, and a communication path is formed from the end surface to the recess. In a side seal device for a rotary fluid machine that is provided through the side seal itself and uses a two-phase fluid as the working fluid, the pressure generated in the recess on the sliding surface side of the side seal is P ₁ . The effective cross-sectional area of the concave portion of the side seal on which pressure P ₁ acts in the axial direction is B, the pressure of the sealing liquid in the liquid supply path that acts on the end surface opposite to the sliding surface is P ₀ , and this When the effective cross-sectional area of the end face of the side seal on which pressure P ₀ acts in the axial direction is A, and the desired value of the gap width δ between the sliding surface of the side seal and the opposing surface is δ _r , P ₀ By specifying the cross-sectional area B corresponding to the values of P ₀ , P ₁ , δ _r and A so that A=P ₁ B, the gap width δ is always kept at a preset desired value δ _r . It is characterized by being designed to be retained.

(Embodiments of the invention) Examples of the invention will be described below with reference to the drawings. In Fig. 1, 1 and 2 are two rotating bodies constituting a rotating fluid machine, for example, as shown in Fig. 2, a rotary engine rotates around two different rotation axes parallel to each other. Two relatively rotating bodies, such as a casing and a rotor, one of which is usually fixed. In a rotary engine, one axis is stationary, but below, a case where both rotating bodies 1 and 2 are not stationary will be described. The arrow a in FIG. 1 indicates the axis vector.

The side seal 3 is loosely fitted into a groove 5 carved in the opposing surface 4 of one of the rotary bodies 2, and is freely movable in the axial direction within a certain range. This groove 5
A liquid supply path 6 provided through the rotating body 2 (hereinafter referred to as the rotating body) is connected to. A recess 8 is provided on the side of the sliding surface 7 of the side seal 3, and the pressure (static pressure) P ₀ acts. Further, the side seal 3 is provided with a communication passage (or aperture) 10 that passes through the side seal itself and communicates from the end surface 9 side to the recess 8 side.

Note that the pressure P ₀ of the sealing liquid sent from the fluid supply path 6 acts on the side seal 3 in the axial direction.
The effective cross-sectional area of the end face 9 of is A, and the pressure (static pressure) generated in the recess 8 on the sliding surface 7 side of the side seal is
P ₁ , and B is the effective cross-sectional area of the recess 8 of the side seal on which this pressure P ₁ acts in the axial direction.

Such side seals can be applied, for example, as seen in FIG. In FIG. 2, the sealing liquid supply path 6 is communicated with a reservoir 12 provided on the inner peripheral surface of the rotating body 2 via a radial flow path 11. A sealing liquid is supplied to this reservoir, and the pressure P ₀ of this liquid is maintained at a constant value within the reservoir or liquid supply path 6 by the centrifugal force at that location.
In the figure, reference numeral 13 denotes an expansion/contraction chamber into which a pressure two-phase fluid as a working fluid is introduced. In this case, if the two-phase fluid used as the working fluid is hot steam, water, which is the same substance as the steam, is suitable as the sealing liquid.

In the above configuration, when pressure fluid is introduced into the expansion chamber 13, this expansion chamber rotates in the direction of expansion, and the rotating body 2 of the rotary fluid machine starts rotating at a predetermined constant speed. Note that the pressure P _e at the points indicated by black dots in both FIGS. 1 and 2 is determined by the gap δ between the sliding surface 7 of the side seal 3 and the other rotating body 1 that faces the sliding surface 7 in the axial direction. is the average pressure of the sealing liquid flowing from the

Next, the design procedure of the side seal device according to the present invention will be explained with reference to FIG.

First, as prerequisites for design, we recommend the specifications of the rotating fluid machine, and determine P ₀ , P ₁ and the minimum gap width δ _r that is considered necessary and sufficient to maintain the machine's functions without causing any problems in its operation. are selected independently of each other.

Also, under the condition that P _e < P ₁ < P ₀ , P ₁ is replaced by the above P
It is determined independently of _e , P ₀ and δ _r . However, in this case, the flow rate of the sealing liquid supplied via the fluid supply path 6 and the values of the expected effective cross-sectional areas A and B of the end surface 9 and the recess 8 of the side seal 3 described above, respectively, are taken into consideration. This P ₁ in relation to them
It is desirable to select the value appropriately.

In this way, when the values of P ₀ , P ₁ , P _e and the gap width δ _r, which is the most important design point, are determined, the flow rate G ₁ of the sealing fluid passing through the communication passage (restriction) 10 is determined. Assuming that a is a constant determined by the cross-sectional area of the communicating path 10, the flow rate coefficient, etc., it is approximately expressed as G ₁ =a√ ₀ − ₁ (1).

Further, the total flow rate _G2 of the sealing liquid flowing out from the gap between the sliding surface 7 of the side seal 3 and the opposing surface of the rotating body 1 is approximately can be obtained from G ₂ = b√ ₁ − _e (2).

Now, C is the flow coefficient, and the gap width of the above gap is δ,
If the length of the gap is l, then b = C, δ, l, but since the values of C and l are constant, it is clear that δ and b correspond one-to-one. It is.

Note that between G ₁ and G ₂ described above, the following relationship exists: G ₁ =G ₂ (3) due to the continuous flow condition.

P ₀ , P ₁ , P _e and δ in the above equations (1) to (3)
Each value of (δ _r ) has already been determined.

Here, the value of A is finally determined, and the value of the effective cross-sectional area B of the recess 8 is specified from equation (4) so that P ₀ A=P ₁ B (4).

(Operation and Effect of the Invention) When B is determined in this way corresponding to each value of P ₀ , P ₁ , P _e , G ₁ , G ₂ , δ _r and A, in FIG. The upward pressure acting on the end surface 9 of the side seal and the downward pressure acting on the recess 8 are determined by the gap width δ between the sliding surface 7 of the side seal and the opposing surface of the rotating body 1 that is a preset desired value. δ
Since the gap width is exactly balanced when the gap width reaches _r , the side seal comes to rest at a position where this gap width is maintained.

In other words, when the gap width δ becomes smaller than δ _r due to some reason, such as vibration or thermal expansion difference, the flow rate G ₂ decreases and G ₂ and Since the equal G ₁ decreases, the pressure P ₁ increases with respect to P ₀ , as seen from equation (1). As the pressure P ₁ increases, in FIG.
Pressure P ₁ is applied to the side seal 3 so as to enlarge the gap δ
acts downward on the concave portion 8 of (δ _r ). Therefore, it is possible to maintain the side seal in a stable floating state at all times at the predetermined gap _δr position where the amount of leakage of the working fluid is substantially zero.

Further, even if δ becomes larger than the predetermined δ _r for some reason, it is assumed that no explanation is necessary because it returns to the original δ _r by the same effect as described above.

As described above, according to the present invention, the gap δ
is always held at the necessary and sufficient minimum value δ _r ,
A remarkable effect is obtained in that a stable sealing state including zero leakage of working fluid can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing an application example thereof, and FIG. 3 is a graph diagram for explaining the operation. 1, 2...Rotating body, 3...Side seal, 4...
...Opposing surface, 5...Groove, 6...Fluid supply path, 7...
Sliding surface, 8... recess, 9... end face, 10... communicating path (diaphragm).

Claims (1)

[Claims] 1. A side seal provided between axially opposing surfaces of two rotating bodies that rotate relative to each other around two different rotational axes, at least one of which is stationary, is one side seal. The rotating body (hereinafter referred to as the rotating body) is fitted into a groove formed on the opposing surface thereof so as to be freely movable in the axial direction within a certain range. A sealing liquid supply path passing through the side seal is connected, a recess is provided on the sliding surface side of the side seal, and the pressure of the sealing liquid in the liquid supply path acts on the end surface opposite to the sliding surface. In a side seal device for a rotary fluid machine, in which a communication path leading from the end face to the recess is provided through the side seal itself, and a two-phase fluid is used as the working fluid, the sliding of the side seal P ₁ is the pressure generated in the recess on the surface side, B is the effective cross-sectional area of the recess of the side seal on which this pressure P ₁ acts in the axial direction, and B is the liquid supply path that acts on the end surface opposite to the sliding surface. The pressure of the sealing liquid inside is P ₀ , the effective cross-sectional area of the end face of the side seal on which this pressure P ₀ acts in the axial direction is A , and the gap width δ between the sliding surface of the side seal and the opposing surface facing the side seal By specifying the cross-sectional area _B corresponding to the values of P ₀ , P ₁ , δ r and A so that P ₀ A=P ₁ B , where δ _r is the desired value of A side seal device for a rotary fluid machine, characterized in that a width δ is always maintained at a preset desired value _δr . 2. Claim 1, characterized in that the sealing liquid guided to the groove of the side seal through the liquid supply path is water, and the two-phase fluid as the working fluid is hot steam. Side seal device for rotating fluid machinery.