NO20230725A1

NO20230725A1 - Rod seal module

Info

Publication number: NO20230725A1
Application number: NO20230725A
Authority: NO
Inventors: Kim Felix Aas; Ekaterina Sinkevich
Original assignee: Olvondo Tech As
Priority date: 2023-06-26
Filing date: 2023-06-26
Publication date: 2024-12-27

Description

Title: Rod seal module

FIELD OF THE INVENTION

The present invention relates to a rod seal module for a reciprocating machine with a reciprocating rod provided in a bore of a housing. The present invention also relates to a reciprocating machine with a reciprocating rod provided in a bore of housing.

BACKGROUND OF THE INVENTION

Reciprocating machinery is a type of machines in which piston performs the main function of converting the energy of the working fluid (steam, gas, liquid). The piston is connected to the crankshaft of the crank mechanism which is used to convert the rotational movement of the shaft into the reciprocating motion of the piston (or vice versa). With a changing of piston position in the cylinder the parameters of working fluid are changing accordingly. During operation, the energy of the working fluid can decrease (engine) or increase (pump, compressor, etc.).

To avoid that working fluid is exiting the working volume of the cylinder, a rod seal module must be provided circumferentially around the reciprocating rod.

One object of the present invention is to provide an improved rod seal module.

SUMMARY OF THE INVENTION

The present invention relates to a rod seal module for a reciprocating machine with a reciprocating rod provided in a bore of a housing, wherein the rod seal module comprises:

- an outer seal sleeve configured to be provided in contact with an inner surface of the bore;

- a sealing ring configured to be provided in contact with the rod;

- a spring housing threaded together with a seal seat fixed inside of the outer seal sleeve;

- a pneumatic piston longitudinally movable inside of the spring housing, wherein the pneumatic piston and the spring housing are defining a spring compartment; - a spring located within the spring compartment;

wherein the spring is configured to bias the pneumatic piston towards the sealing ring.

The rod seal module is defined with a longitudinal direction corresponding to the longitudinal axis of the reciprocating rod.

The sealing ring may be a polymer seal.

A lower end of the pneumatic piston may be provided in wedging contact with an upper end of the sealing ring. A lower end of the sealing ring may be provided in wedging contact with a tapered protrusion of the seal seat.

The spring may be configured to bias the pneumatic piston in a longitudinal direction towards the sealing ring.

The spring may be configured to bias the pneumatic piston in a longitudinal direction downwardly towards the sealing ring.

The spring may be configured to bias the sealing ring radially inwards against the reciprocating rod due to the wedging contact between the lower end of the pneumatic piston and the upper end of the sealing ring.

The rod seal module comprises:

- a washer provided in the spring compartment;

- an inlet fluid line for transferring a seal fluid to the spring compartment, wherein the washer may be located between the inlet fluid line and the spring.

The washer may be configured to bias the pneumatic piston towards the sealing ring via the spring.

The washer may be longitudinally moveable within the spring compartment.

The inlet fluid line may be provided as a fluid bore through the outer seal sleeve and/or through the spring housing.

The pneumatic piston may be longitudinally displaceable relative to the spring housing.

The pneumatic piston may be longitudinally displaceable a distance relative to the spring housing. This distance is dimensioned to allow thermal expansion of the sealing ring during operation of the reciprocating machine.

The spring may comprise a number of cup springs.

The present invention also relates to a reciprocating machine with a reciprocating rod provided in a bore of housing, wherein the machine comprises:

- a rod seal module according to the above sealingly engaged between the bore and the reciprocating rod;

- a fluid source for supplying fluid to the spring compartment via an inlet fluid line.

The fluid source may comprise a pump for supplying pressurized fluid to the spring compartment.

The fluid source may comprise a control system for controlling the pump, thereby controlling the pressure of the pressurized fluid suppled to the spring compartment.

LIST OF DRAWINGS

Fig. 1 is a cross sectional view of the rod seal module of a reciprocating machine; Fig. 2 illustrates the reciprocating machine and the rod seal module.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described in detail. Initially, it is referred to fig. 2, where a reciprocating machine RM is shown schematically. The reciprocating machine RM has an outer housing H comprising a piston chamber C1 and a bore B. A reciprocating rod R is provided in the bore B of the housing H and is extending from the outside of the housing H and further into the piston chamber C1 via the bore B. A piston (not shown) is typically secured to the reciprocating rod R. The piston is dividing the piston chamber into two compartments.

In the description below, the term “upper” is used to denote parts that are relatively closer to the piston compartment C1 than other parts. Similarly, the term “lower” is used to denote parts that are relatively more distant from the piston compartment C1 than other parts. It should be noted that the reciprocating machine may have a different orientation than the one shown in fig. 1. A central longitudinal axis CA of the reciprocating rod R is indicated in fig. 2.

The reciprocating rod R will move back and forth through the bore depending on the pressure difference between the two compartments of the piston chamber.

The reciprocating machine RM may be a heat pump, a reciprocating air compressor, a ea Stirling engine etc..

The reciprocating machine RM further comprises a rod seal module 1 for providing a seal between the reciprocating rod R and the inner surface of the bore B of the housing H. The purpose of the rod seal module 1 is to prevent fluid (gas or liquid) from exiting or entering the bore B. The rod seal module 1 is also defined with a central longitudinal axis CA corresponding to the central longitudinal axis of the reciprocating rod R.

In fig. 2, reference number 70 is denoting a further seal for providing a seal around the reciprocating rod R in the transition area between the bore B and the piston compartment C1. Reference number 60 is a chamber located in the bore B between the rod seal module 1 and the further seal 70.

It is now referred to fig. 1, where the rod seal module 1 is shown more in detail. The rod seal module 1 is defined with a longitudinal direction LD coinciding with the central longitudinal axis CA of the rod R. As shown in fig. 1, all of, or most of the parts forming the rod seal module 1 are provided circumferentially around the rod R, i.e. they are approximately cylindrical in shape and have a through opening for the rod R.

The rod seal module 1 comprises an outer seal sleeve 10 configured to be provided in contact with an inner surface of the bore B. The rod seal module 1 further comprises a sealing ring in the form of a polymer seal 2 configured to be provided in contact with the rod R and a spring housing 4 threaded together with a seal seat 7. The spring housing 4 and seal seat 7 are both located within the outer seal sleeve 10. The seal seat 7 comprises a tapered protrusion 7a protruding radially inwardly towards the reciprocating rod R. It should however be noted that the seal seat 7 itself is not in contact with the reciprocating rod R.

The rod seal module 1 further comprises a pneumatic piston 3 floating longitudinally inside of the spring housing 4. The pneumatic piston 3 and the spring housing 4 are defining an annular spring compartment 6. A spring 5 is located within the spring compartment 6. The spring 5 here comprises a number of cup springs stacked above each other in the annular spring compartment 6. As the spring housing 4 is fixed in relation to the outer seal sleeve 10, the spring 5 will bias the pneumatic piston 3 towards the polymer seal 2. As shown in fig. 1, a lower end of the pneumatic piston 3 is provided in wedging contact with an upper end of the polymer seal 2, as represented by an angle α1 between the lower end of the pneumatic piston 3 and a line L1 being oriented perpendicular to the longitudinal direction LD. Similarly, the angle α1 is also the angle between the upper end of the polymer seal 2 and the line L1.

In the present embodiment, the spring 5 is configured to bias the pneumatic piston 3 in the longitudinal direction LD downwardly towards the polymer seal 2. In fig. 1, it is shown that the pneumatic piston 3 may be longitudinally displaceable a distance D relative to the spring housing 4.

It is also shown in fig. 1 that a lower end of the polymer seal 2 is provided in wedging contact with a tapered protrusion 7a of the seal seat 7, as indicated by the angle α2 between the line L1 and the lower end of the polymer seal 2. The angle α2 is also the angle between the line L1 and the tapered protrusion 7a of the seal seat 7.

Hence, as the spring 5 is biasing the pneumatic piston 3 towards the polymer seal 2, the polymer seal 2 will be forced inwardly into sealing contact with the reciprocating rod R.

It should be noted that the spring biased pneumatic piston 3 also allows thermal expansion of the polymer seal 2 during operation of the reciprocating machine RM.

The rod seal module 1 further comprises a ring-shaped washer 12 provided in the annular spring compartment 6. The washer 12 has a width W adapted to fit accurately within the spring compartment 6, thereby forming a piston within the spring compartment 6. The washer 12 is located above and in contact with the spring 5.

The rod seal module 1 further comprises an inlet fluid line 21 for transferring a seal fluid to the spring compartment 6. The inlet fluid line 21 is in the present embodiment a number of fluid bores provided through the sleeve 10 and spring housing 4. The fluid bores of the sleeve 10 is aligned with a fluid bore provided in the housing H. Hence, fluid is allowed to flow from the outside of the housing H, through the housing H, further through the sleeve 10 and down through the spring compartment 4 to a position above the washer 12 in the spring compartment 6.

It is now referred to fig. 2 again. Here it is shown that the reciprocating machine 1 comprises a fluid source FS for supplying fluid to the spring compartment 6 via the above inlet fluid line 21. The fluid source FS here comprises a pump P for supplying pressurized fluid to the spring compartment 6 and a control system CS for controlling the pump P. Hence, the pressure of the fluid supplied into the inlet fluid line 21 can be controlled.

As described above, the spring 5 is biasing the pneumatic piston 3 towards the polymer seal 2. An additional biasing force may be applied by applying a fluid pressure above the washer 12, causing the washer 12 to move downwardly and compress the spring 5 from above, thereby increasing the force applied by the pneumatic piston 3 towards the polymer seal 2.

Hence, it is achieved that the spring 5 will apply a constant or near constant biasing force to the pneumatic piston 3 and hence to the polymer seal 2. An additional, adjustable, biasing force may be applied to the pneumatic piston 3 and hence to the polymer seal 2 by controlling the fluid pressure in the inlet fluid line 21 and hence the position of the washer 12 within the spring compartment 6.

It should be noted that the seal rod module 10 further may comprise sealing rings (not shown), such as O-rings etc. between the respective parts, in order to prevent fluid from exiting the reciprocating machine 2.

It should further be noted that the housing H may comprise a fluid outlet FO above the seal rod module 1. Here, fluid may be allowed to exit from the chamber 60.

Assembly of the rod seal module 1

The assembly of the rod seal module 1 will now be described. Initially, the spring housing 4 and seal seat 7 are separated from each other. First, (one by one) the washer 12, the spring 5, the pneumatic piston 3 and the seal ring 2 are inserted into the spring housing 4. Then, the seal seat 7 is secured to the spring housing 4, thereby holding the washer 12, the spring 5, the piston 3 and the seal ring 2 longitudinally in place between the spring housing 4 and the seal seat 7. Next the housing 4 is inserted into the sleeve 10 and is abutting against a protrusion 10a protruding radially inwardly towards the rod R. The rod seal module 1 may further comprise an end piece 11 secured to the lower end of the sleeve 10. The end piece 11 is abutting against the lower end of the seal seat 7. Hence, the sleeve 10 and the end piece 11 are keeping all other parts of the rod seal module 1 in place.

LIST OF REFERENCE NUMBERS

1 rod seal module

2 seal ring

3 pneumatic piston

4 spring housing

5 spring

6 spring compartment

7 seal seat

10 outer seal sleeve

12 washer

21 inlet fluid line

CS control system

FS fluid source

P pump

LD longitudinal direction

RM reciprocating machine

Claims

1. A rod seal module (1) for a reciprocating machine (RM) with a reciprocating rod (R) provided in a bore (B) of a housing (H), wherein the rod seal module (1) comprises:

- an outer seal sleeve (10) configured to be provided in contact with an inner surface of the bore (B);

- a sealing ring (2) configured to be provided in contact with the rod (R);

- a spring housing (4) threaded together with a seal seat (7) fixed inside of the outer seal sleeve (10);

- a pneumatic piston (3) longitudinally movable inside of the spring housing (4), wherein the pneumatic piston (3) and the spring housing (4) are defining a spring compartment (6);

- a spring (5) located within the spring compartment (6);

wherein the spring (5) is configured to bias the pneumatic piston (3) towards the sealing ring (2).

2. The rod seal module (1) according to claim 1, wherein a lower end of the pneumatic piston (3) is provided in wedging contact with an upper end of the sealing ring (2) and/or wherein a lower end of the sealing ring (2) is provided in wedging contact with a tapered protrusion (7a) of the seal seat (7).

3. The rod seal module (1) according to any one of the above claims, wherein the spring (5) is configured to bias the pneumatic piston (3) in a longitudinal direction (LD) towards the sealing ring (2).

4. The rod seal module (1) according to claim 3, wherein the spring (5) is configured to bias the sealing ring (2) radially inwards against the reciprocating rod (R) due to the wedging contact between the lower end of the pneumatic piston (3) and the upper end of the sealing ring (2).

5. The rod seal module (1) according to any one of the above claims, wherein the rod seal module (1) comprises:

- a washer (12) provided in the spring compartment (6);

- an inlet fluid line (21) for transferring a seal fluid to the spring compartment (6), wherein the washer (12) is located between the inlet fluid line (21) and the spring (5).

6. The rod seal module (1) according to any claim 5, wherein the washer (12) is configured to bias the pneumatic piston (3) towards the sealing ring (2) via the spring (5).

7. The rod seal module (1) according to any one of the above claims, wherein the pneumatic piston (3) is longitudinally displaceable relative to the spring housing (4).

8. A reciprocating machine (RM) with a reciprocating rod (R) provided in a bore (B) of housing (H), wherein the machine (RM) comprises:

- a rod seal module (1) according to any one of claims 1 - 7 sealingly engaged between the bore (B) and the reciprocating rod (R);

- a fluid source (FS) for supplying fluid to the spring compartment (6) via an inlet fluid line (21).

9. The reciprocating machine (RM) according to claim 8, wherein the fluid source (FS) comprises a pump (P) for supplying pressurized fluid to the spring compartment (6).

10. The reciprocating machine (RM) according to claim 9, wherein the fluid source (FS) comprises a control system (CS) for controlling the pump (P), thereby controlling the pressure of the pressurized fluid suppled to the spring compartment (6).