SCREW SPINDLE PUMP

Abstract

The invention relates to a screw spindle pump (1) with a housing (2) which has an inlet (22) and an outlet (21) for a medium, with two spindles (3, 4) which are designed as shafts with respectively at least one external screw thread (31, 41), wherein the spindles (3, 4) are mounted next to each other in the housing (2) and the screw threads (31, 41) engage in each other in order to convey the medium from the inlet (22) to the outlet (21). The invention provides that each spindle (3, 4) is mounted in an axial bearing (5.1, 5.2) and the axial bearings (5.1, 5.2) are arranged diagonally opposite each other.

Claims

1. A screw spindle pump with a housing which has an inlet and an outlet for a medium, with two spindles which are designed as shafts with at least one external screw thread each, wherein the spindles are mounted next to each other in the housing and the screw threads engage in each other in order to convey the medium from the inlet to the outlet, wherein each spindle is mounted in an axial bearing and the axial bearings are arranged diagonally opposite each other.

2. The screw spindle pump according to claim 1, wherein each spindle is mounted in precisely one axial bearing.

3. The screw spindle pump according to claim 1, wherein at least one axial bearing is designed as a roller bearing.

4. The screw spindle pump according to claim 1, wherein at least one spindle (3, 4) is mounted in at least one additional radial bearing (6.1, 6.2) in the housing (2).

5. The screw spindle pump according to claim 4, wherein each spindle is mounted in the housing on both sides of the screw thread in two radial bearings.

6. The screw spindle pump according to claim 4, characterised in that at least one radial bearing (6.1, 6.2) is designed as a sliding bearing.

7. The screw spindle pump according to claim 4, wherein the at least one axial bearing and/or the at least one radial bearing is arranged in a flow of the medium.

8. The screw spindle pump according to claim 4, wherein at least one lubrication pocket and/or one lubrication groove is arranged in at least one of the radial bearings.

9. The screw spindle pump according to claim 8, wherein the lubrication pocket and/or lubrication groove has an inlet and an outlet which is fluidically connected to the medium conveyed.

10. The screw spindle pump according to claim 4, wherein the axial bearing abuts against one of the radial bearings.

11. The screw spindle pump according to claim 4, wherein the axial bearing is arranged on the side of the radial bearing facing away from the screw thread.

12. The screw spindle pump according to claim 1, wherein the screw spindle pump has a direct drive for driving one of the spindles.

13. The screw spindle pump according to claim 1, wherein the screw spindle pump is single-flow.

Description

[0027] An exemplary embodiment of the invention is explained below with reference to the drawings. They show:

[0028] FIG. 1 a longitudinal sectional view through an exemplary embodiment of a screw spindle pump according to the invention and

[0029] FIG. 2 a cross-sectional view through a spindle mounting according to FIG. 1.

[0030] FIG. 1 shows a longitudinal sectional view through an exemplary embodiment of a single-flow screw spindle pump 1 according to the invention. The screw spindle pump 1 has a housing 2, in which two axially parallel, counter-rotating spindles 3, 4 are mounted. The housing 2 has a suction-side inlet 22 and a pressure-side outlet 21. Both on the inlet 22 and on the outlet 21, a flange is respectively arranged on a connector, wherein FIG. 1 only shows the inlet connector with the inlet flange 22b, via which the screw spindle pump 1 can be coupled to upstream devices or suction lines. The outlet connector in the embodiment shown is above the sectional plane; the pump can be connected to downstream devices via an outlet flange. The inlet 22 for the medium entering the screw spindle pump 1 has an inlet chamber 22a, which is arranged upstream of the spindles 3, 4 in the axial direction of said spindles. The outlet 21 of the housing 2 for the medium exiting the screw spindle pump 1 has an outlet chamber 21a, from which branches off a connector or an outlet flange, through which the conveyed medium can then exit. On the suction side, the inlet chamber 22a enlarges from the flange 22b toward the spindles 3, 4. The structure of the screw spindle pump 1 can however also be reversed and can have the inlet on the side of the outlet and the outlet on the side of the inlet of the embodiment shown with an outlet chamber tapering toward the outlet flange.

[0031] The screw spindle pump 1 has a first, driven spindle 3, whose one spindle end 32 is guided through a sealed opening in the housing 2. On this spindle end 32, a drive not shown, e.g., a direct drive, can be arranged in order to drive the first spindle 3. Via a gearing mechanism not shown, e.g., two gear wheels with the same number of teeth, the torque of the driven first spindle 3 can be transmitted to the second spindle 4. Both spindles 3, 4 have external screw threads 31, 41, have the same pitch, and mesh with each other so that the medium is conveyed from the inlet 22 to the outlet 21 during rotation of the spindles 3, 4. It is in principle also possible for the second spindle 4 to be driven via the screw threads 31, 41.

[0032] The spindles 3, 4 are mounted on their inlet-side end sections in radial bearings 6.1, 6.2 within the housing 2. On the outlet side, the driven first spindle 3 is mounted on a shaft shoulder in a radial bearing 6.2 and an additional axial bearing 5.2. The shaft shoulder is adjoined by the shaft section which comprises the spindle end 32 and is guided out of the housing 2. On its outlet-side shaft end, the second spindle 4 is only mounted in the radial bearing 6.1. The radial bearings 6.1, 6.2 are designed as sliding bearings in the exemplary embodiment. On the inlet side, an axial bearing 5.1 is additionally arranged on the second spindle 4 in order to transfer occurring axial forces via an axial bearing seat 8.1 into the housing 2. Correspondingly, a second axial bearing 5.2 is mounted on the outlet side in another axial bearing seat 8.2 in order to support the first spindle 3. Axial forces that arise during operation of the screw spindle pump 1 and act on the spindles 3, 4 are transferred via the two diagonally arranged axial bearings 5.1, 5.2 via the respective axial bearing seats 8.1, 8.2 into the housing 2. Both the axial bearings 5.1, 5.2 designed as roller bearings and the radial bearings 6.1, 6.2 designed as sliding bearings are arranged in the flow of the medium. To each spindle 3, 4 is assigned only precisely one axial bearing 5.1, 5.2; the axial bearings 5.1, 5.2 can be designed to be acting on both sides and are fixed via a shaft collar and a shaft nut on the respective spindle 3, 4.

[0033] Both spindles 3, 4 are respectively mounted in a combined radial bearing 6.1 and 6.2, which are fixed in the housing 2. The combined radial bearings 6.1, 6.2 are sliding bearings with a common bearing body 6 for both spindles 3, 4; the bearing points in the exemplary embodiment are formed in the bearing body 6; alternatively, bearing bushings can be inserted into the bearing body 6. The combined radial bearings 6.1 and 6.2 are arranged in the flow of the medium. The two axial bearings 5.1, 5.2 abut against the respective radial bearing 6.1, 6.2 on the outside. The medium conveyed is guided from the inlet 22 through the chamber 22a to the first inlet-side axial bearing 5.1 and the inlet-side radial bearing 6.1. Through the first axial bearing 5.1, the conveyed medium is guided to the bearing point of the second spindle 4 in the radial bearing 6.2; the inlet-side radial bearing 6.1 of the first spindle 3 is located directly in the medium flow. The design of the first axial bearing 5.1 as roller bearing enhances the inflow of the conveyed medium as a result of the direct adjacency of the two bearings and as a result of the pump effect through the roller bearing body in the axial bearing 5.1. The housing 2 respectively forms a free space 9 between the bearing body 6 of the radial bearings 6.1, 6.2 and the screw threads 31, 41. The shaft diameters of the spindles 3, 4 are smaller in this free space 9 than in the bearing body 6. Conveyed medium moreover passes through recesses in the housing 2 from the inlet chamber 22a into the free space 9 with the shaft shoulders 32, 42 and is guided by the rotation of the screw threads 31, 41 to the outlet-side free space 9 and thus to the bearing points of the outlet-side radial bearings 6.1, 6.2. With the front sides facing the screw threads 31, 41, the outlet-side radial bearings 6.1, 6.2 are also located directly in the conveyed medium flow; the outlet-side axial bearing 5.2 is located in the flow direction downstream of the radial bearing 6.2. On the front side of the radial bearings 6.1, 6.2 are formed inlets 72 and outlets 71 for lubrication grooves or lubrication pockets, the function and structure of which are explained below.

[0034] FIG. 2 shows a sectional view through the combined radial bearing 6.1, 6.2 and the housing 2 of the screw spindle pump 1 of FIG. 1 with a view toward the axial bearing 5.2. The radial bearing consists of a bearing body 6 with two bores 63, 64 for forming the bearing points for the shaft end of the second spindle 4 and the shaft shoulder of the first spindle 3. The bearing body 6 is inserted into the housing 2 and fixed there. In the housing 2, recesses 25 surrounding the bearing body 6 are formed. On the inlet side, the medium to be conveyed enters the inlet chamber 22a through the inlet 22 and is transported to the bearings 6.1, 6.2, 5.1. Through the bearings and in particular through the free spaces 25, the medium is transported through the free space 9 to the screw threads 31, 41 and through them to the outlet-side free space 9. On the outlet side, the conveyed medium under pressure passes from the free space 9 between the screw threads 31, 41 and the outlet-side radial bearings 6.1, 6.2 through the recesses 25, and a minor portion thereof through the bearings 6.1, 6.2, 5.2, into the outlet chamber 21a and from there exits the pump.

[0035] Two lubrication grooves 7 are respectively formed in two bores 63, 64 of the bearing body 6. The grooves 7 extend in the axial direction and open on the front sides of the bearing body 6 so that conveyed medium can be used as lubricant independently of the conveying direction and direction of rotation of the pump. More than two lubrication grooves 7, which are preferably uniformly distributed over the periphery of the bores 63, 64, can also be formed in the bores 63, 64 or, where applicable, in the bearing bushings. The grooves 7 have a substantially semi-circular cross-section. As described above, the conveyed medium can enter the lubrication grooves 7 through the front-side inlets 72 in order to uniformly distribute the medium between the spindles 3, 4 and the bearing points of the combined radial bearing 6.2 so that sufficient and uniform lubrication is brought about.

[0036] The grooves can also have a different cross-sectional shape. Lubrication pockets that are fluidically connected to the delivery flow, i.e., are provided with an inlet and an outlet, can also be formed in the bores.

[0037] With only two axial bearings 5.1, 5.2, the described embodiment of the screw spindle pump 1 allows a construction of the mounting that is independent of the direction of rotation and thus independent of the conveying direction. All bearings are located in the main delivery flow and are completely lubricated with medium. The bearing bodies 6 are exchangeably mounted in the housing 2 so that they can be easily exchanged if they must be replaced as a result of wear or adapted to another embodiment with different spindles 3, 4. The bearing bodies 6 are attached to the recesses 25 in one housing wall 26 so that the entire flow of the conveyed medium impinges on the front sides of the radial and axial bearings 5.1, 5.2, 6.1, 6.2 and makes lubrication with medium possible. The diagonal arrangement of the axial bearings 5.1, 5.2 with a bearing on the pressure side of the spindle 3 and a bearing on the suction side of the second spindle 4, each on the sides of the radial bearings 6.1, 6.2 facing away from the screw threads 31, 42, ensures a bearing construction of the same type on both bearing sides with bearing and lubrication properties that are independent of the direction of rotation and thus of the conveying direction. In an embodiment of the axial bearings 5.1, 5.2 as roller bearings, the pump effect generated by the rolling bodies is utilized to improve lubrication of the radial sliding bearings 6.1, 6.2. The mounting is designed to be point-symmetric so that a corresponding force distribution in the mounting is maintained even if the direction of rotation of the spindles is reversed. The respective inlet of the one conveying direction then becomes the outlet in the reverse conveying direction and vice versa.

LIST OF REFERENCE SYMBOLS

[0038] 1 screw spindle pump [0039] 2 housing [0040] 21 outlet [0041] 21a outlet chamber [0042] 22 inlet [0043] 22a inlet chamber [0044] 22b flange [0045] 26 housing wall [0046] 3, 4 spindles [0047] 31, 41 screw thread [0048] 5.1, 5.2 axial bearing [0049] 6 bearing body [0050] 6.1, 6.2 radial bearing [0051] 63 bore [0052] 64 bore [0053] 7 lubrication groove [0054] 71 outlet [0055] 72 inlet [0056] 8.1 axial bearing seat [0057] 8.2 axial bearing seat [0058] 9 free space