EP3653880A1 - Rotary pump with mechanical seal - Google Patents

Abstract

A rotating pump is presented with at least one driven conveying element (10, 11) which is arranged in a product space through which the product to be conveyed flows and is driven by means of a shaft (12, 13) protruding from the outside into the product space, the shaft ( 12, 13) is sealed against a wall (50) of the product space, and wherein the seal is designed as a mechanical seal (51, 52) to be mounted on the product side and includes a form-fitting position securing device to allow the mechanical seal (51, 52) to rotate and move The pump is characterized in that the position securing device comprises a securing element (61) running approximately perpendicular to an axial direction of the shaft (12, 13) through the wall (50) .

Description

The invention relates to a rotating pump with at least one driven conveying element, which is arranged in a product space through which the product to be conveyed flows and is driven by means of a shaft projecting into the product space from the outside, and wherein the shaft is sealed against a wall of the product space, the Sealing is designed as a mechanical seal to be assembled on the product side and includes a form-fitting positional lock in order to prevent the mechanical seal from rotating and the mechanical seal from being displaced in the direction of the product space.

Correspondingly constructed pumps are known both as flow pumps and as positive displacement pumps.

A known measure for sealing the shaft against the wall is e.g. the use of shaft seals. However, these are only of limited reliability and are particularly out of the question if the type of product to be conveyed requires a particularly secure seal, e.g. when conveying toxic substances or in the hygienic area, e.g. in the food and or cosmetics industry.

The use of mechanical seals, which ensure a very good seal, has prevailed in these areas. However, this is bought through a complex seal structure. The seal generally has at least one rotating section connected to the shaft and one stationary section mounted in the wall.

For the seal to function properly, the stationary section must be secured axially and against rotation. In this case, the axial securing must also prevent the mechanical seal from moving in the direction of the product space, since otherwise the function of the seal cannot be guaranteed in the event of a negative pressure in the product space. For this purpose, this section usually has a flange or a receptacle, which is fixed in the wall in a non-positive and / or positive manner, for example by screwing with several screws or by shrinking.

In many cases, especially for pumps for hygienic products such as food or cosmetics, it is not desirable or simply not possible to arrange a flange or a receptacle in the product space, since this impairs the product flow and the corresponding contours are difficult to clean. The flange must therefore be installed from outside the product area. This is disadvantageous for several reasons.

To assemble the flange, the shaft must be completely pulled out of the product space. With many pumps, this requires a complete separation of the product space and the pump drive. Since at the same time the rotating section of the mechanical seal can only be installed from the product side, the replacement or maintenance of the seal is very complex. In addition, when the product space is brought together with the installed stationary section of the seal and the pump drive, there is a risk that the seal will be damaged by uncontrolled contact with the shaft.

From the EP3214311A1 A pump is known in which the shaft is sealed by means of a mechanical seal to be installed on the product side, with the mechanical seal being secured in the bearing by a securing element arranged outside the product space. Here, however, the securing element is difficult to fasten, since it is located in a narrow leakage space between the wall of the product space and a bearing housing.

It is therefore the object of the invention to provide a rotating pump which is improved with regard to the problems described.

This object is achieved according to the invention by a rotating pump with at least one driven conveying element, which is arranged in a product space through which the product to be conveyed flows and is driven by means of a shaft projecting into the product space from the outside, and the shaft against a wall of the product space is sealed, the seal being designed as a mechanical seal to be installed on the product side and comprising a form-fitting positional lock in order to prevent the mechanical seal from rotating and the sliding of the mechanical seal in the direction of the product space, which is further developed by the positional lock being approximately perpendicular to one Axial direction of the shaft includes securing element extending through the wall.

Because the securing element runs through the wall perpendicularly to the axial direction of the shaft, the securing element ends outside the product space in an area in which the securing element can be easily handled.

In a preferred embodiment of a pump according to the invention, the mechanical seal can comprise a stationary sleeve inserted into the wall, in which a first sliding ring is received, and a rotating sleeve fastened on the shaft, in which a second sliding ring is received, the securing element can engage in a recess of the stationary sleeve. In this version, the position of the mechanical seal can be secured particularly easily.

According to a possible embodiment of the invention, the securing element can comprise a pin guided through a bore in the wall.

In an advantageous embodiment, the bore can have an enlarged diameter at one end remote from the seal and can be provided with an internal thread. Furthermore, the pin can be received with an end remote from the seal in a sealing screw which is screwed into the bore. In this way, on the one hand, the pin is fixed in the bore in a particularly simple manner, and on the other hand the bore is sealed off from the surroundings, so that no air can be drawn through the bore into the product space if a vacuum occurs in the product space.

In a further preferred embodiment of a pump according to the invention, the shaft can extend outside the product space into a bearing housing, a leakage space being formed between the wall of the product space and the bearing housing, and the leakage space being covered on the outside by a sheet-shaped engagement protection, which can be attached to the wall by means of the sealing screw.

A pump according to the invention can be a two-spindle screw pump.

The invention is explained in more detail below with the aid of a few figures.

Figur 1:

Eine Pumpe,

Figur 2:

Eine horizontale Schnittdarstellung einer Pumpe.

Show it:

Figure 1:

A pump,

Figure 2:

A horizontal sectional view of a pump.

In Figure 1 A pump 1 is shown, which is a single-flow screw pump. The pump 1 has a gear section 2 and a pump section 3.

The gear section consists of a bearing housing 5 with an inspection opening which is closed by a cover 6. The pump section comprises a product inlet 7 and a product outlet 8.

A leakage space is arranged between the gear section 2 and the pump section 3, which is secured by an intervention protection 9.

The internal structure of the pump 1 is in Figure 2 shown. Two displacement bodies 10, 11 in the form of delivery screws are arranged in a product space of the pump section 3. By turning the two displacement bodies 10, 11 in opposite directions, the product to be conveyed is removed from the in Figure 2 promoted invisible product inlet to the product outlet 8.

The displacers 10, 11 are fastened on the ends to shafts 12, 13 and secured there by nuts 14, 15. In order to prevent the displacement bodies 10, 11 from rotating on the shafts 12, 13, they can have suitable positive locking elements.

The displacers 10, 11 mesh with one another with very little play in order to enable efficient product conveyance. For this, the shafts 12, 13 must be mounted precisely and stiffly. The shafts 12, 13 are supported in the gear section 2.

The bearing housing 5 of the gear section 2 consists of a main body 16 and a closing body 17, which are detachably fastened to one another, for example by a screw connection.

For the exact alignment of the end body 17 with the main body 16, the end body 17 has a flat first stop surface 18 which bears against a corresponding stop surface of the main body. A surface normal of the stop surface 18 runs approximately parallel to the axial direction of the shafts 12, 13.

Furthermore, the end body 17 has a circumferential second stop surface 19 which bears against a corresponding stop surface of the main body 16 on the inside. A surface normal of the stop surface 19 extends approximately perpendicular to the axial direction of the shafts 12, 13 at each point of the stop surface 19. Starting from the second stop surface 19, the closing body 17 tapers in the direction of the pump section 3.

The main body 16 has receiving bores 22, 23 into which radially acting bearings 24, 25 are inserted, in the example shown needle bearings. The inner rings of the needle bearings are shrunk onto the respective shafts, while the outer rings and the needle cages of the needle bearings are each axially fixed in the receiving bores 22, 23 between a stop shoulder and a clamping ring.

The closure body 17 has receiving bores 30, 31, in which radially and axially acting bearings 32, 33 are inserted. In the example shown, the radially and axially acting bearings 32, 33 each comprise three angular contact ball bearings. Other numbers of Ball bearings are possible, with each of the bearings 32, 33 comprising at least two angular contact ball bearings positioned opposite to one another for good storage.

The inner rings of the bearings 32, 33 are fixed on the shafts 12, 13 by means of locknuts 34, 35. The outer rings of the bearings 32, 33 are fixed in the receiving bores 30, 31 in each case between a stop shoulder and within the bearing housing 5 with fixing plates 36, 37 screwed to the end body 17.

The shaft 10 serves as a drive shaft and therefore has a drive pin 38 which protrudes from the bearing housing 5. For this purpose, the receiving hole 30 is designed as a through hole, while the receiving hole 33 is designed as a blind hole.

Between the radially acting bearings 24, 25 on the one hand and the radially and axially acting bearings 32, 33, on the other hand, a synchronous gear 40 is arranged, through which the shafts 12, 13 are rotationally coupled.

A first pinion 41 of the synchronous gear 40 is fixed in a rotationally fixed manner on the shaft 10 by means of a key connection. The pinion 41 is axially fixed between a stop shoulder of the shaft 12 and the inner rings of the bearing 32.

A second pinion 42 must be rotatably mounted on the shaft 13 for the rotational alignment of the displacement bodies 10, 11 with respect to one another. For this purpose, the pinion 42 comprises a ring gear 43, which is seated on a sleeve 44. The sleeve 44 is fixed in a rotationally fixed manner on the shaft 13 by means of a feather key connection and, like the pinion 41, is axially fixed between a stop shoulder of the shaft 13 and the inner rings of the bearing 33.

The sleeve 44 has a circumferential projection 45, on which the ring gear 43 rests. A ring 46 bears against the projection 45 from the other side. The ring gear 43 and the ring 46 are screwed together and are thus non-positively fixed to the projection 45.

To set the correct angular position of the displacement bodies 10, 11 relative to one another, the screwing of the ring 46 to the ring gear 43 is loosened somewhat, so that the ring gear can be rotated against the sleeve 44 and thus against the shaft 13. Once the correct position has been reached, the screw connection of the ring gear 43 with the ring 46 is tightened again.

During operation of the pump 1, an oil sump is provided in the bearing housing 5, in which the pinions 41, 42 of the synchronous gear 40 are immersed. The rotating pinions 41, 42 generate an oil mist that cools and lubricates the bearings 24, 25, 32, 33.

To assemble the gear section 2, the inner rings of the bearings 24, 25 are first shrunk onto the shafts 12, 13. Then the pinions 41, 42, the fixing disks 36, 37 and then the bearings 32, 33 are placed one after the other on the shafts 12, 13 and fixed by means of the locknuts 34, 35.

Next, the shafts 12, 13 with the bearings 32, 33 are inserted into the receiving bores 30, 31 and fixed to the end body 17 by screwing the fixing plates 36, 37.

Finally, the end body 17 with the assembled shafts 12, 13 is inserted into the main body 16. The free ends of the shafts 12, 13 are guided through the receiving bores 22, 23 of the main body.

At its end facing the pump section 3, the end body 17 is tapered so that it can be inserted into the main body 16 without any problems. Only when the stop surface 19 enters the main body 16 is the closing body 17 guided closely. The stop surface 19 extends in the axial direction of the shafts 12, 13 over a length which is significantly less than the length of the bearings 32, 33, namely less than 35%, preferably less than 30%, particularly preferably less than 25% of the length of the bearings 32.33. In the example shown, the extent of the stop surface 19 in the axial direction of the shafts 12, 13 is approximately 17% of the length of the bearings 32, 33.

The insertion of the end body 17 into the main body 16 is further facilitated in that the extent of the stop surface 19 in the axial direction of the shafts 12, 13 is less than the length of the radially acting bearings 24, 25. As a result, the shafts 12, 13 are already supported by the bearings 24, 25 before the stop surface 19 enters the main body 16. Thus, the end body 17 can not tilt during assembly.

As soon as the stop surface 18 lies completely against the main body 16, the closing body is fixed by screws. The passages of the shafts 12, 13 and the drive pin 38 through the bearing housing 5 are sealed by means of shaft sealing rings.

The passage of the shafts 12, 13 through a wall 50 of the product space is sealed by two identical mechanical seals 51, 52, of which only the mechanical seal 52 is described in detail below for the sake of simplicity.

The mechanical seal 52 comprises a stationary sleeve 53, which is inserted into a receiving bore 45 of the wall 50. A first sliding ring 55 is received in the stationary sleeve 53 in a rotationally fixed manner. Furthermore, the mechanical seal 52 comprises a rotating sleeve 56 which is fixed on the shaft 13 between a stop shoulder and the displacer body 11. In the rotating sleeve 56, a second sliding ring 57 is rotatably received.

The slide rings 55, 57 lie against one another with plane ground sliding surfaces and are axially prestressed against one another by spring elements 58.

To ensure that the mechanical seal 52 functions reliably, it is necessary for the stationary sleeve 53 to be secured against rotation in the receiving bore 54. At the same time, it must be prevented that the stationary sleeve 53 is pulled out of the receiving bore 54 in the direction of the product space when a negative pressure occurs in the product space while compressing the spring elements 58.

For this purpose, the stationary sleeve 53 has a recess 60 on its outer circumference, into which a securing element 61 running through the wall 50 engages. In addition, the stationary sleeve 53 in the region of the recess 60 can have a flattening (not shown) in order to simplify the correct alignment of the sleeve 53 during assembly.

The securing element 61 comprises a pin 62 which runs through a bore 63 in the wall 50. At one end remote from the mechanical seal 52, the bore 63 is widened and provided with an internal thread 64. A sealing screw 65 is screwed into the internal thread 64, and the pin 62 is received in the shaft thereof.

The length of the pin 62 is dimensioned such that when the sealing screw 65 is screwed in completely, it engages in the recess 60 of the stationary sleeve 53 without exerting any radial force on the stationary sleeve 53. A radial force would cause the sleeve 53 to deform and the sealing effect of the mechanical seal 52 to be impaired.

The sealing screw 65 seals the bore 63 against the surroundings of the pump 1, so that no air can be drawn through the bore 63 in the case of a negative pressure in the product space.

The sealing screw 65 also serves to fasten the engagement protection 9 to the wall 50.

The mechanical seals 51, 52 can be easily serviced or repaired from the product side without opening the bearing housing 5. For this purpose, an outlet cover 70 and a product space section 71 are removed and the displacers 10, 11 are pulled off the shafts 12, 13. The rotating sleeve with the second slide ring 57 can then be pulled off the shaft.

Next, the securing element 61 is released, so that the stationary sleeve 53 with the first slide ring 55 can also be pulled out of the receiving bore 54 in the direction of the product space.

The mechanical seal 52 is installed in the opposite sequence.

Instead of the single-acting mechanical seals 51, 52 shown, the pump 1 can be equipped with double-acting mechanical seals. Such double-acting mechanical seals can be flushed from the inside during operation, for this purpose flushing channels (not shown) are provided in the wall 50. In this case, the correct rotational alignment of the mechanical seals in the receiving bores is particularly important so that the flushing openings of the mechanical seals are in contact with the ends of the flushing channels.

Claims (7)

Rotating pump with at least one driven conveying element (10, 11) which is arranged in a product space through which the product to be conveyed flows and is driven by means of a shaft (12, 13) projecting into the product space from the outside, the shaft (12, 13) is sealed against a wall (50) of the product space, and the seal is designed as a mechanical seal (51, 52) to be installed on the product side and includes a form-fitting positional lock in order to twist the mechanical seal (51, 52) and to move the mechanical seal (51 , 52) in the direction of the product space, characterized in that the position securing device comprises a securing element (61) running approximately perpendicular to an axial direction of the shaft (12, 13) through the wall (50). Pump according to claim 1, characterized in that the mechanical seal (52) - A in the wall (50) inserted stationary sleeve (53) in which a first sliding ring (55) is received, and - A rotating sleeve (56) fastened on the shaft (13), in which a second sliding ring (57) is received, wherein the securing element (61) engages in a recess (60) of the stationary sleeve (53). Pump according to one of claims 1 or 2, characterized in that the securing element (61) comprises a pin (62) guided through a bore (63) in the wall (50). Pump according to claim 3, characterized in that the bore (63) has an enlarged diameter at one end remote from the seal and is provided with an internal thread (64). Pump according to claim 4, characterized in that the pin (62) is received with one end remote from the seal in a sealing screw (65) which is screwed into the bore (63). Pump according to claim 5, characterized in that the shaft (12, 13) extends outside the product space into a bearing housing (5), a leakage space being formed between the wall (50) of the product space and the bearing housing (5), and wherein the leakage space is covered to the outside by a sheet-shaped engagement protection (9) which is attached to the Wall (50) is attached. Pump according to one of claims 1 to 6, characterized in that the pump is a two-spindle screw pump (1).

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