EP3196466A1 - Displacement pump - Google Patents

Abstract

A rotating externally mounted positive displacement pump with at least two synchronously driven displacement bodies (7, 8), which are fastened at the end to associated shafts (9, 10), the shafts (9, 10) being each supported by a first, radially acting bearing (13, 14) ) and a second, radially and axially acting bearing (15,16) are mounted, and wherein the shafts (9,10) by a synchronous transmission (17) are coupled together, is further developed in that the bearings in receiving bores of a one-piece housing are fitted and that the synchromesh between the respective camps is arranged.

Description

The invention relates to a rotating externally mounted positive displacement pump with at least two synchronously driven displacement bodies, which are fixed end to associated shafts, wherein the shafts are each supported by a first, radially acting bearing and a second, radially and axially acting bearing, the bearing in receiving bores a unitarily manufactured housing are fitted, and wherein the shafts are coupled together by a synchronous transmission.

Rotary positive displacement pumps have been known in the form of gear pumps since the early 17th century. In modern pumps, the displacers are mounted on shafts which are stored outside a product section through which the product to be conveyed flows.

The pump is driven externally by a motor which drives one of the shafts. The second shaft can be driven by the mutually meshing displacement body. However, this leads in particular in screw pumps to heavy wear of the displacer, which on the one hand reduces the life and on the other hand leads to a product load due to abrasion, which can not be tolerated especially when using the pump in the hygienic area. As a hygienic area is to be understood in particular the food and cosmetics industry.

It has therefore prevailed mainly a type of pump in which the second shaft is coupled via a synchronous transmission with the first shaft. The displacers can then be designed so that they work contactless and practically wear-free.

The bearings of the shafts require particularly high demands from the pumps described. Because of the non-contact operation, the storage must be very stiff and low-play, to avoid unwanted contact with the displacer. At the same time, bearing must accommodate large axial forces in certain types of pumps, especially single-screw pumps. To meet these requirements, a certain axial distance is required between the radial and axial bearings, which determines the outer dimensions of the pumps. By this distance, the sufficient cooling and lubrication of the bearings is difficult especially at high speeds.

The synchronous transmission is usually located outside of the bearings of the waves, which additionally increases the length of the pump. There are isolated pumps known in which the synchromesh between the bearings is arranged. Since the diameter of the pinion of the transmission is greater than the axial distance of the shafts, however, the pinions can not be introduced from any side through the bearing bores in the housing, so that the housing must be constructed in two parts, the bearing bores for the radial bearings in a part and the bearing bores for the thrust bearings are provided in the other part. Due to the low permissible position tolerances, this design increases the manufacturing and assembly costs of the pump immensely.

It is therefore an object to provide a pump which is improved in particular with regard to the abovementioned disadvantages.

This object is achieved according to the invention by a rotating externally mounted positive displacement pump with at least two synchronously driven displacement bodies, which are fastened end side on associated shafts, wherein the shafts are respectively supported by a first, radially acting bearing and a second, radially and axially acting bearing , the bearings are fitted in receiving bores of a one-piece housing, and wherein the shafts are coupled together by a synchronous transmission, which is thereby developed, that the synchronous transmission between the respective bearings is arranged and has two intermeshing pinions whose diameter is greater than the axial spacing of the shafts, wherein the pinions each have a ring gear which is fixed on a support body, and wherein the largest outer diameter of the support body is smaller as the center distance of the waves.

The corresponding structure of the pump has several advantages. The one-piece construction of the housing manufacturing and assembly tolerances of the housing parts are reduced to each other, so that the production of the pump is easier and safer. As a one-piece construction of the housing in the context of the invention is understood to mean any structure in which all the bearing bores of the shaft bearings are provided in the same part of the housing. This does not exclude that the housing includes other separate parts that do not include bearing bores.

At the same time, the length of the pump can be reduced because the synchronous transmission fits in the functionally required distance between the bearings. The synchronous transmission can additionally contribute to sufficient lubrication and cooling of the bearings by immersing the sprockets of the synchronous transmission circumferentially in an oil sump and deliver the oil in the direction of the bearings as oil mist. By positioning the oil sump between the bearings a uniform lubrication and cooling of all bearings is possible with minimal effort.

The fact that the largest outer diameter of the support body is smaller than the axial distance of the shafts, the waves can be inserted with mounted support bodies through the bearing bores in the housing. The sprockets can be pushed through a separate housing opening between the bearings on the waves and attached to the support bodies.

The support bodies are non-positively and / or positively secured on the shafts according to an embodiment of the invention. This is done for example by shrinking and / or a known feather key connection.

The sprockets are fixed according to a development of the invention non-positively on the support bodies. The frictional connection makes it possible for the rotational orientation of the displacer each other at least one of the sprockets to loosen and twist on the support body. In this case, the sprockets can be freely rotated in a large angle range, preferably by one or more full revolutions with dissolved adhesion.

The frictional attachment of the sprockets on the support bodies is carried out according to an exemplary embodiment of the invention by means of screwed clamping plates.

In an exemplary embodiment of the invention, the pump is a single-flow screw pump.

• Figur 1: eine Pumpe gemäß eines Aspekts der Erfindung,
• Figur 2: eine horizontale Schnittdarstellung einer Pumpe gemäß eines weiteren Aspekts der Erfindung,
• Figur 3: eine vertikale Schnittdarstellung einer Pumpe gemäß eines weiteren Aspekts der Erfindung,
• Figur 4: einen horizontalen Schnitt durch die Abdichtung des Produktabschnitts einer Pumpe,
• Figur 5: ein Sicherungsblech einer Pumpe.

The invention will be explained below with reference to some exemplary drawings. Show it:

• FIG. 1 a pump according to one aspect of the invention,
• FIG. 2 FIG. 3 is a horizontal sectional view of a pump according to another aspect of the invention. FIG.
• FIG. 3 FIG. 3 is a vertical sectional view of a pump according to another aspect of the invention. FIG.
• FIG. 4 : a horizontal section through the sealing of the product section of a pump,
• FIG. 5 : a lock washer of a pump.

FIG. 1 shows a pump 1 in a perspective view, which consists essentially of a drive section 2 and a product section 3. In the example shown, it is a hygienic single-spindle screw pump.

The drive section 2 of the pump 1 has a drive shaft journal 4, with which the pump 1 can be coupled to a drive motor, not shown. The product section 3 of the pump 1 has a product inlet 5 and a product outlet 6. In the case of reversible operation of the pump 1, product feed 5 and product discharge 6 can be interchanged as a function of the conveying direction.

The internal structure of the pump 1 is in the Figures 2 and 3 shown. In the product section 3, two intermeshing displacement screws 7, 8 are arranged, which are driven by two parallel shafts 9, 10. The displacement screws 7.8 are attached to the shafts 9,10 and releasably secured to this, in the example shown by means of the screw 11,12.

The shafts 9, 10 extend from the product section 3 into the drive section 2, where they are initially supported by radially acting needle bearings 13, 14 and by radial and axial angular contact ball bearings 15, 16. The angular contact ball bearings 15,16 consist in the illustrated example of three consecutively arranged bearings, which are described for clarity as a bearing. Between the bearings 13,14 and 15,16 a synchromesh 17 is arranged with intermeshing pinions 18,19. The synchronizer 17 transmits the impressed on the drive shaft journal 4 in the shaft 10 movement on the shaft 9, so that the displacement screws 7 and 8 rotate synchronously in opposite directions.

To the bearings 13,14,15,16 and the synchromesh 17 of a single-flow screw pump 1 are particularly demanding. The displacement screws 7.8 engage in contact with minimal gap with each other in order to achieve high efficiency. In order to avoid contact of the displacement screws 7,8, by which they can be destroyed, therefore, both the synchromesh 17 and the storage must be extremely stiff and low backlash. In addition, due to the single-flow design, high axial forces act on the shafts 9, 10, in particular at high delivery rates and high-viscosity or pasty products, which must be absorbed by the angular contact ball bearings 15, 16.

To be able to withstand the high loads, the bearings 13,14,15,16 must be constantly cooled. For this purpose, an oil bath 20 is provided in the drive section 2 of the pump 1. The pinions 18,19 dive into an oil sump and generate in the drive section 2 an oil mist, which enters the bearings 13,14,15,16 and lubricates and cools them at the same time.

The shafts 9, 10 are sealed at the product-side end of the drive section 2 by shaft seals 21, 22 in order to prevent the escape of oil from the drive section 2. Another shaft seal 23 is provided for sealing the drive shaft journal 4.

When mounting the pump 1, there is the difficulty that the diameter of the pinion 18,19 functionally greater than the axial distance of the shafts 9,10, while the diameter of the mounting holes 24,25 for the outer rings 26,27 of the angular contact ball bearings 15,16 smaller than the center distance of the shafts 9,10 must be. Thus, the shafts 9, 10 can not be inserted into the drive section 2 of the pump 1 with the pinions 18, 19 mounted through the receiving bores 24, 25.

Therefore, the assembly is carried out as follows: On the shafts 9, 10, the inner rings 28, 29 of the needle bearings 13, 14, support bodies 30, 31 for the pinions 18, 19 and the angular contact ball bearings 15, 16 are mounted prior to assembly. For this purpose, the inner rings 28,29 of the needle bearings 13,14 and the angular contact ball bearings 15,16 shrunk onto the shafts 9,10, while the support members 30,31 are fixed by feather key not shown on the shafts 9,10.

In the housing 34 of the drive section 2, the outer rings 35,36 of the needle bearings 13,14 are fixed with the associated needle cages 41,42 in corresponding mounting holes 37,38.

The mounted on the shafts 9,10 parts 28,29,30,31,15,16 are dimensioned so that their outer diameters are all smaller than the axial distance of the shafts 9,10, so that the pre-mounted shafts through the mounting holes 24,25 can be inserted in the drive section 2 in the direction of the product section 3. The sprockets 39,40 are guided through a mounting hole 43 of the housing during insertion over the shafts 9,10. For axially fixing the shafts 9,10 and the angular contact ball bearings 15,16 then one or more fixing plates 46 are screwed.

After the shafts 9,10 are mounted axially free of play by fixing the angular contact ball bearings 15,16, in the next step, the synchromesh 17 is completely assembled. For this purpose, the sprockets 39,40, which were already placed when inserting the waves 9,10 loose on this, pushed onto the support body 30,31, where they sit with a tight fit and mesh with each other. For this purpose, the support body 30,31 on the side facing away from the product section 3 side stop shoulders 47,48. From the product section 3 side facing clamping plates are 49,50,51,52 set against the sprockets 39,40. The clamping plates 49,50,51,52 are each carried out approximately semi-annular and have end-side steps, so that two clamping plates can be assembled into a flush ring. The assembled rings are then fastened by means of screws to the support bodies 30,31 and press the sprockets 39,40 against the stop shoulders 47,48, whereby they are fixed non-positively.

The fact that the receiving bores 24,25 of the angular contact ball bearings 15,16 and the receiving bores 35,36 of the needle roller bearings 13,14 can be coaxially introduced into the one-piece housing 34, the production with very little play is possible, in particular the risk of a radial offset the individual receiving holes 24,25,35,36 is reduced to each other.

The product section 3, which is constructed from an intermediate flange 53 with product feed 5, a feed housing 54 and a closure flange 55 with product drain 6, adjoins the drive section 2 of the pump. The intermediate flange 53 is supported with a shoulder collar 56 on the housing 34 of the drive section 2, so that a leakage space 58 is formed between it and a drive-side wall 57. This leakage space 58 ensures that oil can escape from the drive section 2 in the event of failure of one of the shaft sealing rings 21, 22 from the pump without contaminating the conveyed product, which is particularly the case when using the pump in the hygiene sector, such as e.g. in the food or cosmetics industry, is of fundamental importance.

The waves 9,10 protrude through gasket seats 59,60 in the wall 57 in the product area and are sealed when passing through the wall 57 by mechanical seals 61,62, which for the sake of clarity in the Figures 2 and 3 are not shown. The structure of these seals is described below with reference to FIG. 4 explained in more detail.

The mechanical seals 61,62 are constructed identically, which is why only the mechanical seal 61 will be described here. All information applies equally to the mechanical seal 62.

The mechanical seal 61 is constructed in two stages and therefore has a stationary portion 63 and two rotating sections 64,65. The first rotating portion 64 is seated on the drive side on the shaft 9 and is held by axially screwed into the shaft 9 and pins 66,67 axially and rotationally. The stationary portion 63 consists of two slip rings 68,69, which are supported by a spring ring 70 to each other. The unit of the two sliding rings 68,69 and the spring ring 70 are enclosed in a sleeve 71 which is inserted into the sealing seat 59 and here axially supported on a projection 72.

The second rotating portion 65 in turn consists of a sliding ring 73, which is taken in a pot 74, which is placed on a step 75 of the shaft 9 and is clamped there by the displacement screw 7. In the pot 74 drivers 76 are screwed, which prevent rotation of the slide ring 73 relative to the pot 74.

Due to the force of the spring ring 70, the sliding ring 68 is pressed against the rotating portion 64 and the sliding ring 69 against the sliding ring 73, whereby they rest tightly against each other and seal the product space 77 against the leakage space 58. In particular, the slip rings 69 and 73 are made of product-compatible and low-wear material.

The space between the slip rings 68,69,73 and the shaft 9 is rinsed by a product compatible liquid which may be e.g. can be distilled water. This serves to cool the slip rings and the removal of possibly between the slip rings penetrating product components. Supply and removal of the liquid via channels in the wall 57, which are not shown for clarity.

During operation of the pump 1, it may happen that there is negative pressure in the product space 77. In order to prevent it sleeve 71 is pressed by the ambient pressure in the product space 77, whereby in the worst case impurities can get into the product, the sleeve 71 projects on the drive side beyond the wall 57 and there has a circumferential groove 78. In this groove 78 fingers 79,80 ( Fig. 5 ) of an inserted from the outside into the leakage chamber 58 locking plate 81 a. As a result, the sleeve 71 is locked axially, so that it can not be pressed into the product space.

At one point, the groove 78 has an axial cut-out 82, which cooperates with a projection 83 of the locking plate 81 to secure the sleeve 71 against rotation.

The locking plate 81 is in the FIG. 5 shown in more detail. The locking plate has two external fingers 79,80 and a central web 84, which are adapted to the groove bottom of the groove 78 in the contour. Overall, these include an angle of slightly more than 180 °, so that the fingers are 79.80 elastically bent during insertion of the locking plate 81 to the outside and then spring back to their original position. The elastic deformation is supported by slots 85,86, which when inserting the locking plate via locking screws 87 ( Fig. 4 ) to grab. In the middle of the web 84, a small tab 88 is provided, which is used to form the projection 83. This can, as in Fig. 4 shown, a small plate 89 are attached to the tab 88, for example by spot welding. Alternatively, the tab 88 itself may be bent or crimped slightly out of the plane of the locking plate 81 to form the projection 83.

At the free end of the locking plate 81, a narrow strip is bent by about 90 ° and thus acts as engagement 90 for the leakage space 58. This leaves a sufficient gap to tighten the locking screws 87 after inserting the locking plate 81 with a key and thus the locking plate 81 to fix.

The assembly and disassembly of the mechanical seals 61,62 is particularly simple and takes place with dismantled end flange 55 from the product side.

The rotating portion 64 is guided from the product side on the shaft and pushed to the pins 66,67, which even before mounting the drive section 2 in threaded holes of the Shafts 9, 10 are screwed in. Then, the stationary portion 63 is guided with the slip rings 68,69, the spring ring 70, and the sleeve 71 on the shaft 9 and pushed into the seal seat 59, wherein the sleeve 71 projects up to the circumferential groove 78 on the drive side of the wall 57 , Next, the locking plate 81 is inserted into the leakage space 58, so that the fingers 79,80 and the web 84 engage in the groove 78. The sleeve is thereby aligned so that the projection 83 engages in the cutout 82 and thus secures the sleeve against rotation. After complete insertion of the locking plate, the locking screws 87 are tightened to fix the locking plate.

Finally, the rotating portion 65 is pushed with the pot 74 and the sliding ring 73 up to the level 75 on the shaft 9. By mounting the displacement screws 7.8, the mechanical seals 61,62 are fixed.

During assembly of the displacement screws 7, 8, these are preferably aligned with one another prior to being pushed onto the shafts 9, 10, so that the corresponding threads mesh with one another. The displacement screws 7, 8 and the product-side ends of the shafts 9, 10 have shape-matching fitting elements, so that rotation of the displacement screws 7, 8 on the shafts 9, 10 is excluded. The positive connection is additionally secured by the screw 11,12.

Since the displacement screws 7,8 can be placed on the shafts 9, 10 only by the positive locking in discrete angular positions, it is necessary to rotate the shafts 9, 10 against each other in order to set an optimum contactless alignment of the displacement screws 7, 8 to one another. This is important to avoid premature wear of the displacement screws 7.8.

For this purpose, the clamping plates 49,50 are slightly loosened by the mounting hole 43 for the ring gear 39, so that the ring gear 39 can rotate on the support body 30. Then, the gap between the displacement screws 7, 8 is adjusted by turning. In the correct position of the displacement screws 7,8 to each other, the clamping plates 49,50 are tightened again, so that the ring gear 39 is fixed again rotatably.

After adjusting the displacement screws 7.8, the end flange 55 is placed on the conveyor housing. At the drive section 2 of the pump, the mounting opening is closed by a lid 91. Thereafter, the pump 1 is ready for use.

LIST OF REFERENCE NUMBERS

1:

pump

2:

driving section

3:

product section

4:

Drive shaft journal

5:

product inlet

6:

product runoff

7,8:

Verdrängerschrauben

9.10:

waves

11.12:

fittings

13.14:

needle roller bearings

15.16:

Angular contact ball bearings

17:

synchromesh

18.19:

pinion

20:

oil bath

21,22,23:

Shaft seals

24.25:

Receiving bores (angular contact ball bearings)

26.27:

Outer rings (angular contact ball bearings)

28.29:

Inner rings (needle roller bearings)

30.31:

supporting body

32.33:

Inner rings (angular contact ball bearings)

34:

casing

35.36:

Outer rings (needle roller bearings)

37.38:

Receiving bores (needle roller bearings)

39.40:

Cassettes

41.42:

needle cages

43:

mounting hole

44.45:

ball cages

46:

Fixing plate

47.48:

stop shoulders

49,50,51,52:

clamping plates

53:

Wafer

54:

conveyor housing

55:

end flange

56:

neck collar

57:

wall

58:

leakage chamber

59.60:

seal seats

61.62:

Mechanical seals

63:

stationary section

64.65:

rotating sections

66.67:

pencils

68.69:

Glide

70:

Spring washer 45

71:

shell

72:

head Start

73:

sliding ring

74:

pot

75:

step

76:

takeaway

77:

product space

78:

Groove 5

79.80:

finger

81:

Locking plate

82:

countersink

83:

head Start

84:

web

85.86:

slots

87:

locking screws

88:

flap

89:

sheet

90:

Trap guard

91:

cover

Claims (5)

Rotating externally mounted positive displacement pump with at least two synchronously driven displacement bodies (7, 8), which are fastened at the end to associated shafts (9, 10), wherein the shafts (9, 10) are each supported by a first, radially acting bearing (13, 14). and a second, radially and axially acting bearing (15,16) are mounted, the bearings (13,14,15,16) in receiving bores (24,25,37,38) of a one-piece manufactured housing (34) are fitted, and the shafts (9, 10) being coupled to one another by a synchronous transmission (17),
characterized in that
the synchronous transmission (17) is arranged between the respective bearings (13, 14, 15, 16) and has two meshing pinions (18, 19) whose diameter is greater than the axial spacing of the shafts (9, 10),
the pinions (18, 19) each have a toothed rim (39, 40) which is fastened on a carrier body (30, 31), and wherein the largest external diameter of the carrier bodies (30, 31) is smaller than the center distance of the shafts (9, 9) , 10). Pump according to claim 1, characterized in that the supporting bodies (30, 31) are positively and / or positively fixed on the shafts (9, 10). Pump according to one of claims 1 or 2, characterized in that the sprockets (39,40) are non-positively attached to the support bodies (30,31). Pump according to claim 3, characterized in that the sprockets (39,40) by means of screwed clamping plates (49,50,51,52) on the support bodies (30,31) are attached. Pump according to one of the preceding claims, characterized in that the pump is a single-flow screw pump.

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