WO2010112108A2

WO2010112108A2 - Screw spindle pump arrangement

Info

Publication number: WO2010112108A2
Application number: PCT/EP2010/001096
Authority: WO
Inventors: Robert Eckert; Thorsten Zellmann; Georg Leutgeb
Original assignee: Robert Bosch Gmbh
Priority date: 2009-03-31
Filing date: 2010-02-23
Publication date: 2010-10-07
Also published as: US20120121450A1; CN102449311A; JP2012522166A; WO2010112108A3; DE102009015685A1

Abstract

The invention relates to a screw spindle pump arrangement having a low-pressure connection, a high-pressure connection, a drive spindle, and at least one idling spindle. A feed section of the idling spindles can be divided into two feeding segments that can be driven either in series or in parallel. A screw spindle pump arrangement is thereby created with little effort, wherein two operating modes can be selected without controls technology. Two tap connections that can be connected by a connecting line are provided in a center area of the feed section. The connecting line can be blocked and the low-pressure side tap connection can thereby be connected to the high-pressure connection, and the high-pressure side tap connection can be connected to the low-pressure connection. A series circuit (high pressure, low volume flow rate) is created by the open connecting line, corresponding to a screw spindle pump according to the prior art. With the connecting line blocked, and the simultaneous pressure medium flow paths indicated above, the screw spindle pump arrangement can be simply operated as a parallel circuit (low pressure, high volume flow).

Description

Screw pumps arrangement

description

The invention relates to a screw pump arrangement according to the preamble of patent claim 1.

Screw pumps usually have two or three mutually parallel and intermeshing spindles which are set in rotation by a working machine (for example an electric motor). The spindles are accommodated in a housing, with only minimal distances between the outer sides of the spindles and the housing.

As a result of the rotation, the fluid to be delivered is conveyed along the spindles in the spaces which result in the thread-like intermeshing turns between the spindles and the housing. This results in a low pressure area at one end of the spindles or the housing and at the other end a high pressure area. At the same time, the fluid to be delivered penetrates into the minimum distances between the spindles and the housing and produces a load-bearing and lubricating film.

In the document DE 39 20 901 A1 a screw pump with three spindles is shown. An intermediate drive spindle meshes with two-sided running spindles, along whose helical turns a fluid is conveyed.

In a double-flow design of the screw pump, however, the spindles are not continuously coiled, but in two opposite directions divided coiled sections whose spaces move towards each other during rotation. This results in two low pressure areas at the two ends of the spindles and a high pressure area in the middle of the spindles.

In the document DE 10 2006 061 971 A1 is such a double-flow

Screw pump with two spindles shown.

A disadvantage of screw pumps according to DE 39 20 901 A1, which are driven by constant electric motors, is their low flexibility with respect to. Pump outlet pressure and flow rate.

In contrast, the invention is based on the object to provide a screw pump assembly that is easy to adapt to different requirements regarding. Pump outlet pressure and flow rate.

This object is achieved by a screw pump arrangement according to claim 1.

Further advantageous embodiments of the invention are described in the dependent patent claims.

The screw pump arrangement according to the invention has a high-pressure connection, a low-pressure connection, a drive spindle and at least one running spindle. A conveying path of the running spindle can be divided into two conveying sections, which can be operated or flowed through either in parallel or in series. As a result, a screw pump arrangement is created with little effort, in which two operating states (higher output pressure with lower volume flow or lower output pressure at higher flow rate) can be selected without control technology.

In a particularly preferred further development of the screw pump arrangement according to the invention, two tap connections, which can be connected by a connecting line, are provided on the housing in a middle region of the conveying path. see. The connecting line can be shut off, and thereby the first tap connection in the conveying direction to the high pressure port and the second tap port in the conveying direction can be connected to the low pressure port. Through the open connection line is a series circuit (higher pressure, lower flow) given, which corresponds to a screw pump according to the prior art. With the shut-off connection line and the simultaneous above-mentioned separate pressure fluid flow paths, the screw pump assembly can be easily operated in parallel (lower pressure, higher flow).

In order to separate the end of the first conveying section from the beginning of the second conveying section (or the pressure means located therein), the distance between the two tap connections along the conveying path corresponds at least to the width of the webs of the running spindles. Thus, at least one web prevents pressure medium exchange between the regions of the two tap connections.

In a particularly preferred development, a directional valve is arranged in the connecting line, which is connected via a high-pressure connecting line to the high-pressure port and a low-pressure connecting line to the low-pressure port. This can be switched by valve actuation between series connection and parallel connection.

Preferably, in a spring-biased home position of a directional control valve body, the pressure medium flow path between the tap connections is shut off via the connection line. Instead, the first tap port is connected to the high pressure port and the second tap port is connected to the low pressure port. In a switching position of the valve body, however, the two tap connections are connected to each other via the connecting line.

In an advantageous embodiment, a check valve is arranged in the high pressure connection line, which opens from the directional control valve to a high pressure line which connects the high pressure port to a pump outlet. For reasons of operational safety, a pressure-limiting valve relieving pressure on a tank can be arranged on the high-pressure line. In this case, the Drυe kbegrenzungsventil be pneumatically piloted.

Depending on the design, it may be advantageous if the screw pump assembly has two spindles, whose gears are coiled in the same direction.

For cost reasons, the drive spindle can be driven by a constant two-pole electric motor whose manufacturing costs are lower than those of a controllable electric motor.

Alternatively, the drive spindle can be connected to increase the flexibility or adaptability of output pressure and flow with a speed-controlled electric motor, wherein a pressure sensor connected thereto can be arranged on the high-pressure line.

Preferably, the screw pump assembly according to the invention is used to supply a machine tool with cooling lubricant. In this application, the switching possibility according to the invention is particularly advantageous. The series connection (higher pressure with lower volume flow) is needed with larger tools and the parallel connection (lower pressure with higher volume flow) with smaller tools. Even with different cutting performance of the machine tool, these two operating states of the pump can be used advantageously.

An embodiment of the screw pump assembly according to the invention will be described in detail below with reference to a single figure.

This figure shows a screw pump arrangement according to the invention. It has a known in its basic structure of the prior art screw pump 1, which is shown (in the figure) on the left and in section. Furthermore, the arrangement according to the invention changes or extensions, which are shown as a symbolic diagram and (in the figure) are shown largely right.

The screw pump has an elongated housing, which essentially consists of a housing main section 2 and two end housing covers 3, 4.

In the interior of the housing 2, 3, 4, two running spindles 6 are arranged, which have minimum distances to the adjacent sections of the inner wall 8 of the housing main section 2.

The spindles 6 have circumferentially coiled grooves or gears 10. Between the turns of the gears 10 also circumferentially coiled webs remain 12th

Centrally in the housing main section 2 and between the spindles 6, a drive spindle 14 is arranged, which also has a circumferentially coiled web 16. The web 16 is the other way helically wound than the webs 12 of the spindles 6, wherein the drive spindle 14 meshes with two spindles 6.

At the (in the figure) upper end portion of the drive spindle 14, a shaft portion 18 is formed, which is mounted in the (in the figure) upper housing cover 4 via a rolling bearing 20 and outside of the housing 2, 3, 4 has a connecting portion 22. Via the connection section 22, the drive spindle 14 can be driven by an electric motor (not shown), wherein the electric motor can be a constant motor for cost reasons or can be regulated for reasons of greater flexibility.

By the meshing engagement of the drive spindle 14 with the two spindles 6 they are set in drive in rotation. The limited by the inner wall 8 of the housing main section 2 gears 10 of the spindles 6 are divided by the web 16 of the drive spindle 14 into sections or spaces, the to move during the rotation of the spindles 6 (in the figure) from bottom to top. As a result, pressure medium, which is sucked in at a low pressure port 24, can be conveyed to a high pressure port 26 and thereby compressed.

According to the invention, two axially spaced tap connections 28, 30 are provided in the housing main section 2 in a middle region of the conveying path extending from bottom to top (in the figure). Their dimension transversely to the conveying direction is chosen so that they are in pressure medium connection to the corresponding passage sections of the two spindles 6. In this case, the two tap connections 28, 30 have an axial distance from one another in the conveying direction which corresponds at least to the thickness of the webs 16. This ensures a separation of the two tap connections 28, 30 or the pressure means located in the corresponding passage sections.

In a spring biased position (a) of a valve body of the directional control valve 32, the low pressure port 24 via a low pressure line 34, a low pressure connecting line 36 and a second tap line 38 with the second Tap connection 30 connected. Furthermore, in the o.g. Switched position of the first tap port 28 via a first tap line 40 and a high-pressure connection line 42 connected to a high-pressure line 44. The high pressure line 44 connects the high pressure port 26 to a pump outlet P.

In a switching position (b) of the valve body, which is selectable via a solenoid 46, a pressure medium flow path from the first tap port 28 via the first tap line 40, the directional control valve 32 and the second tap line 38 to the second tap port 30 released.

In the high pressure connection line 42, a check valve 48 is provided which opens from the directional control valve 32 to the high pressure line 44. In the following, the function of the screw pump assembly according to the invention will be explained.

By means of the tapping connections 28, 30 according to the invention and the hydraulic circuit according to the invention, the conveying path of the two running spindles 6 can be operated essentially continuously or alternatively can be divided into two conveying sections 45a, 45b, which can be operated in parallel.

The parallel connection of the two conveying sections 45a, 45b is achieved in the switching position (a) of the valve body of the directional valve 32 shown in the figure. Here, the sucked at a suction port S pressure medium flow on the one hand via the low pressure line 34 to the low pressure port 24 and on the other hand via the low pressure connection line 36 and the second tap line 38 to the second tap port 30. The two conveyor sections 45a, 45b of the spindles 6 are thus operated in parallel, with a first

High-pressure volume flow from the first tap port 28 via the first tap line 40 and via the high-pressure connection line 42 to the pump outlet P flows, while a second volume flow from the high-pressure port 26 via the high-pressure line 44 to the pump outlet P flows. In this case, it is ensured that approximately the same pressure prevails in the high-pressure connecting line 42 and in the high-pressure line 44. Thus, the volume flow at the pump outlet P is comparatively high, while the output pressure at the pump outlet P is comparatively low.

The series connection of the two delivery sections 45a, 45b and a conventional operation of the screw pump arrangement according to the invention is achieved, in which the solenoid 46 is energized and the valve body of the directional control valve 32 shifts to the switching position marked b. As a result, the two tap connections 28, 30 are connected to one another, wherein the pressurized pressure medium flows from the first conveying section 45a via the two tap lines 40, 38 into the second conveying section 45b of the running spindles 6. In the second conveying section 45b then takes place the second part of the pressure increase, wherein the pressure medium with maximum pressure from the High pressure port 26 via the high pressure line 44 to the pump outlet P flows.

In this case, the volume flow is relatively low, while the pressure increase is relatively large.

The check valve 48 arranged in the high-pressure connecting line 42 closes when the two conveying sections 45a, 45b are connected in series and opens when the two conveying sections 45a, 45b are connected in parallel, if approximately the same pressure prevails in the high-pressure connecting line 42 and in the high-pressure line 44.

From the high pressure line 44 further branches off a line 49, in which a pressure relief valve 50 is provided, which relieves the high pressure line 44 to a tank T when an adjustable maximum pressure is exceeded. The pressure relief valve 50 is pneumatically pilot operated and has a continuously adjustable proportional pressure valve.

Furthermore, an electronic pressure sensor 52 and a pressure gauge 54 for monitoring the pump outlet pressure is provided on the high-pressure line 44, the pressure being applied to the pressure gauge 54 via a throttle 56.

The screw pump assembly according to the invention is particularly suitable for the promotion of cooling lubricant in machine tools. In this application, screw pumps are preferred because they have the greatest possible resistance to partially abrasive particles that accumulate in the cooling lubricant.

When changing tools of the associated machine tools or when changing the cutting power changes in the pressure and the flow rate of the cooling lubricant are required, which can be achieved with the screw pump according to the invention, without a speed-controlled electric motor is necessary. For example, in a small tool the comparatively high pressure with the comparatively low volume flow through the Series connection (switching position b) is generated, while in a larger tool, the comparatively low pressure with the comparatively high volume flow through the parallel circuit (switching position a) is generated.

The maximum drive power of the (not shown) electric motor can be in the o.g. Field of application compared to the prior art be reduced by about 40%.

Compared to a variable speed screw pump, the screw pump assembly according to the invention has the advantage in addition to the lower cost that a volume flow reduction is not generated by speed reduction, whereby the carrying property of the cooling lubricant in the areas between the webs 12 and the housing main section 2 could be affected.

Disclosed is a screw pump arrangement with a low-pressure connection, a high-pressure connection, a drive spindle and at least one running spindle. A conveyor line of the spindles is divisible into two conveyor sections, which can be operated either in parallel or in series. As a result, a screw pump arrangement is created with little effort, in which two operating states are selectable without control technology.

In a central region of the conveyor line two connectable by a connecting line tap connections are provided. The connection line can be shut off, and the low-pressure-side tap connection to the high-pressure connection and the high-pressure-side tap connection can be connected to the low-pressure connection. Through the open connection line a series connection (higher pressure lower volume flow) is given, which corresponds to a screw pump according to the prior art. In the closed connection line and the simultaneous above-mentioned pressure medium flow paths, the screw pump assembly can be easily operated in the parallel circuit (lower pressure higher volume flow). LIST OF REFERENCE NUMERALS

1 screw pump

2 housing main section

3, 4 housing cover

6 spindle

8 inner wall

10 course

12 footbridge

14 drive spindle

16 footbridge

18 shaft section

20 rolling bearings

22 connection section

24 low pressure connection

26 high pressure connection

28 first tap connection

30 second tap connection

32 4/2-way valve

34 low-pressure line

36 low-pressure connection line

38 second tap line

40 first tap line

42 high-pressure connection line

44 high pressure line

45a first conveyor section

45b second conveyor section

46 solenoid

48 check valve

49 line

50 pressure relief valve

52 pressure sensor

54 pressure gauge 56 throttle

P pump outlet

S Suction connection T Tank

Claims

claims

A screw-spindle pump arrangement with a low-pressure connection (24) and with a high-pressure connection (26) and with a drive spindle (14) and with at least one running spindle (6), characterized in that a

Conveyor section of the running spindle (6) in two conveyor sections (45a, 45b) is divisible, which are operable either in parallel or in series.

2. screw pump assembly according to claim 1, wherein in a central region of the conveying path two through a

Connecting line (38, 40) connectable tap connections (28, 30) are provided, wherein the connecting line (38, 40) can be shut off, while the first tap in the conveying direction tap (28) to the high pressure port (26) and in Conveying direction second tap port (30) with the low pressure port (24) is connectable.

3. Screw pump assembly according to claim 2, wherein the distance between the two tap connections (28, 30) along the conveying path at least the width of the coiled webs (12) of the running spindles (6).

4. screw pump assembly according to claim 2 or 3, wherein in the connecting line (38, 40) a directional control valve (32) is arranged, which via a high pressure connecting line (42) to the high pressure port (26) and via a low pressure

Connecting line (36) is connected to the low pressure port (24).

5. Screw pump arrangement according to claim 4, wherein in a spring-biased basic position (a) of a valve body of the directional control valve (32), the connecting line (38, 40) is shut off, and thereby the first tap port (28) to the high pressure port (26). and the second tap port (30) are connected to the low pressure port (24), and wherein in a switching position (b) of the valve body, the two tap connections (28, 30) via the connecting line (38, 40) are interconnected.

6. screw pump assembly according to claim 4 or 5, wherein in the high-pressure connecting line (42) a check valve (48) is arranged, which opens from the directional control valve (32) to a high-pressure line (44), the high pressure port (26) with a pump outlet ( P) connects.

7. Screw pump assembly according to one of the preceding claims, wherein a pressure relief valve (50) is connected to the high pressure line (44), which relieves the high pressure line (44) to a tank (T).

8. screw pump assembly according to claim 7, wherein the

Pressure relief valve (50) is pneumatically pilot-controlled.

9. screw pump assembly according to at least one of the claims 3 to 8 with two spindles (6), whose gears (10) are coiled in the same direction.

The screw pump assembly according to at least one of the preceding claims, wherein the drive spindle (14) is driven by a two-pole electric motor.

H .Schnraubenspindelpumpenanordnung according to at least one of the claims 1 to 9, wherein the drive spindle (14) is connected to a variable speed electric motor, wherein on the high pressure line (44) connected to the electric motor pressure sensor (52) is arranged.

2.Schraubenspindelpumpenanordnung according to at least one of the preceding claims for supplying a machine tool with coolant and / or lubricant.