DE209219C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 209219 ^ * / · - CLASS £ 59. GROUP 1/2.

BERLINER MASCHINENBAU-ACT.-GES. formerly LSCHWARTZKOPFF in BERLIN.

Pump shaft directed throttle sections is influenced.

Patented in the German Empire on February 3, 1906.

The axial shaft thrust that occurs in high-pressure centrifugal pumps, steam turbines and the like is usually canceled out by means of relief pistons which run with little play in a correspondingly designed part of the machine housing. Such a piston α, as shown in Fig. Ι of the drawing, 'exerts a constant axial pull P on the shaft, which when P _{1 is} the overpressure on ίο the inside of the piston, Z) ₂ the ϋμΉΐι-' ■. ' diameter of the shaft, D ₁ mean that of the piston, results as

(D ₁ * - Z) ₂ ² ; -. P ₁ = ■ P = const.

Since, however, the axial flow generated by a steam turbine, centrifugal pump, etc. Thrust can only be predicted mathematically with limited accuracy, and since also the axial thrust as a result of the wear and tear inside the machine during the Operation changes, so it is desirable to override that thrust in a way that allows the forces, which change within certain limits, to maintain their equilibrium. The resistance should therefore be larger or smaller, depending on the axial thrust of the machine gets bigger or smaller. The solution to this problem forms the subject of the present invention, its essence therein there is one on the to be exonerated. Shaft seated, inside one by gap seal completed. Body running in space with the alternating axial thrust caused displacement of the wave an increase in the flow resistance for the Pressure medium and thus a pressure opposite to the displacement corresponding to the Shift generated.

In the drawing, FIGS. 2 to 5 show several devices for realizing the Invention schematically.

A piston α runs with the usual small radial play of 0.1 to 0.2 mm in a correspondingly designed part of the fixed housing. At its end walls, the piston is enclosed by two fixed boundary walls, between which it has as much axial play as the elements located inside the machine, e.g. B. the wheels of a centrifugal pump, if a grinding of these elements should be avoided on each other. In the case of a centrifugal pump, experience has shown that this clearance would have to be about 4 to 6 mm, so that the piston would have an axial distance of 2 to 3 mm in its central position against the stationary walls. In FIGS. 2 and 3, this limitation of the possible axial displacement is achieved by special sealing strips on the outside on the pressure side and inside on the free side, while the embodiments of FIGS to come to the plant. In front of or behind the relief piston a (Fi ^ "2 ™ bls * ^ ** sinT

60

Gap seals δ arranged, which are formed in that the shaft or an attached Bush with little play, 0.1 to 0.2 mm, in corresponding fixed wedges runs. ·

The way in which the discharge works is initially based on the. Fig. 2 explains:

In the middle position of the piston α there is a pressure P ₁ in space A , in space B _{i in} front of the piston α a lower pressure p ₂ determined by the pressure drop in ■ the gap seal b , in space C behind the piston a the external pressure p ₀ , because with the mean distance between the sealing strips of 2 to 3 mm at d there is no pressure build-up at this point

can take place in C. The area - ^ --- must

'4 ■

with the arrangement made, it is so much larger than the corresponding area in FIG. 1

ao can be made how the pressure p ₂ lags behind p _x so that the normal axial pressure generated by the pump can still be compensated when the piston is in the middle position.

As if, for one of the reasons mentioned, the axial thrust of the machine acting in the direction of the arrow increases, the shaft and thus the piston a move to the left; the sealing strips c approach each other and, since they offer the flowing working medium an increased flow resistance, cause a pressure build-up in B. Since p ₂ increases, the total pressure exerted on the piston a is increased and now keeps the axial pressure of the machine in equilibrium again.

If the axial thrust of the machine acting in the direction of the arrow is reduced, the shaft is shifted to the right by the relief piston, and a flow resistance is created at d as previously at c. As a result, an increase in pressure is now generated in space C , so that the piston α is now only able to compensate for a lower total pressure than in its central position as a result of the counterpressure on its right end face. The axial pressures generated by the piston and the machine are also now equal to one another.

The operation of an automatic unloader piston of FIG. 4 without sealing strips only in that the in the rooms B and C are not constant over the entire piston surface by movement of the koi bens ä adjusting pressures differs from the above case, but after any Change the law, namely decrease from the inside out or vice versa.

The mode of operation of the arrangement shown in FIG. 3 with the gap seal located behind the piston the following:

With normal axial thrust of the machine, i.e. the middle position of the relief piston, there is a pressure p _v on the end face of the piston α facing pressure chamber A, which sinks to p ₂ < p _x due to the small play at e in chamber C, and finally through the gap seal b to be pulled down to the external pressure p _0.

If the pressure of the machine acting in the direction of the arrow increases, a wave movement to the left takes place, and the decreasing space at c creates a flow resistance for the medium flowing through, so that the counter-pressure on the piston a is caused by the tension in the space C is conditional, becomes lower. The decrease in pressure on the right-hand face of the piston must be such that the piston again maintains the equilibrium with the increased axial pressure of the machine.

If there is a decrease in the axial machine pressure, a wave movement to the right occurs. As a result, a ' flow resistance is formed at d by the approximation of the sealing strips, so that now the pressure p ₂ in space C and thus the total pressure exerted on the piston α to the left increases by the amount by which the axial thrust of the machine has decreased .

The embodiment of Fig., 5 without sealing strips works exactly like that after Fig. 3, only again with the difference that when the piston moves after right or left the specific pressures on the end faces of the piston are not constant are, but decrease according to a certain law.

Claims (4)

Patent Claims: 100 ι. Device for relieving pressure from centrifugal pumps, turbines and fans with a piston seated on the shaft to be relieved, which is influenced by throttle sections directed perpendicularly and parallel to the pump shaft, characterized in that with the one or more perpendicular to the direction of axial thrust. Throttle sections. one or more cylindrical gap diameters are combined in such a way that the gap seals and the throttle sections are flowed through one behind the other by the press fluid used for relief. H5 2. Apparatus according to claim i, characterized in that a gap seal the space in which the relief body works from the main pressure space and a second gap seal around the circumference .the body separates the front of the piston from its rear. 3- device according to claim i, characterized characterized in that a gap seal separates the front of the relief piston from its rear while a second gap seal against the back of the piston, which closes off the atmosphere. : 4. Apparatus according to claim 1 for axially relieved shafts, characterized in that the front and rear surfaces of the relief piston are in free connection with one another, so a counter pressure only occurs when the shaft is moved. .. ■! · ■■ '. 1 sheet of drawings. O O