EP2550456A2

EP2550456A2 - Gear pump

Info

Publication number: EP2550456A2
Application number: EP11709925A
Authority: EP
Inventors: Ulrich Helbing; Arkardiusz Tomzik; Dietrich Witzler
Original assignee: Oerlikon Textile GmbH and Co KG
Current assignee: Oerlikon Textile GmbH and Co KG
Priority date: 2010-03-25
Filing date: 2011-03-18
Publication date: 2013-01-30
Anticipated expiration: 2031-03-18
Also published as: CN103097731A; RU2012145177A; ES2540097T3; RU2530692C2; EP2550456B1; KR101762989B1; MX2012010497A; CN103097731B; US9416781B2; DE102010012653A1; ZA201206874B; US20130034463A1; WO2011117154A3; WO2011117154A2; KR20130009998A

Abstract

A gear pump is described with a plurality of gearwheels which engage into one another in order to convey a medium and are held rotatably in a pump housing. One of the gearwheels is driven by a pump shaft which can be coupled to a drive via a coupling end. In order, in particular at greatly fluctuating operating pressures, to obtain uniform conveying streams even in the case of changing load states within one revolution of the pump shaft, a brake ring is arranged according to the invention on the circumference of the pump shaft, which brake ring acts by way of at least one braking surface on a frictional surface of the pump shaft or on a frictional surface of the pump housing.

Description

gear pump

The invention relates to a gear pump according to the preamble of claim 1.

It is well known that gear pumps are used for conveying and metering fluids, in which the medium to be conveyed is transported between the teeth of two intermeshing gears between a pump inlet and a pump outlet. Thus, very uniform delivery volumes can be set by the majority of the delivery members, so that such gear pumps are preferably used to produce uniform delivery rates, such as, for example, the provision of paints in a paint shop.

Such a gear pump is known for example from DE 10 2005 059 563 AI. In the known gear pump, two intermeshing gears are rotatably supported within a pump housing and connected to a pump shaft. The pump shaft protrudes with a coupling end of the pump housing and can be coupled with a drive shaft of a motor. When using such gear pumps with changing pressure loads on the outlet side or the inlet side or both sides unevenness of the flow rate were observed. Usually, the gears held in the pump housing are driven by the torque transmitted to the pump shaft. In the event that a reversal of the pressure differences between the pump inlet and the pump outlet occurs due to pressure fluctuations, act in addition to the torque of the pump shaft additional pressure forces on the tooth flanks of the gears in the conveying direction, so that, depending on the size of the pressure forces on the gears, a reversal of a motor drive can be made to a standalone drive. This change in the load direction is planted on the entire powertrain away. Due to the torsional backlash in the drive train, it now comes to accelerate and slow down the rotational speed of the gears within a revolution of the pump shaft. This phenomenon immediately leads to an unevenness in the flow during one revolution of the pump shaft.

It is therefore an object of the invention to develop a gear pump of the generic type such that regardless of the Druckver- conditions at the pump inlet and pump outlet as uniform as possible delivery Ström is generated.

This object is achieved in that at the periphery of the pump shaft, a brake ring is arranged, which acts with at least one braking surface on a friction surface of the pump shaft or on a friction surface of the pump housing.

Advantageous developments of the invention are defined by the features and feature combinations of the respective subclaims.

The invention is characterized in that a load reversal at the gears is intercepted by acting on the pump shaft braking torque and does not continue in the entire drive train. As a result, only the games between the tooth flanks of the gears, which affect the conveying uniformity but only slightly. Another advantage of the invention is that independent of the selected seals within the pump defined and relatively high braking torques can be generated on the pump shaft. In addition, higher friction torques can not be generated by means of sealing lips of the usual seals, since they wear out in the shortest possible time and lead to failure. In that regard, the brake ring offers the advantage of tuning both the braking surface and the material of the brake ring to the generation of the braking torque. Depending on the location of the Brake ring can be formed on the pump shaft or on the pump housing, the corresponding friction surface.

However, particularly preferred is the formation of the gear pump according to the invention according to the embodiment, in which the brake ring is rotatably held in the pump housing and in which the braking surface is formed on an inner diameter of the brake ring.

In this case, the friction surface of the pump shaft is preferably formed on the circumference as a circumferential surface whose outer diameter has an excess against the inner diameter of the brake ring. This can already set a predefined bias between the brake ring and the pump shaft. Alternatively, however, it is also possible that the brake ring has a plurality of evenly distributed on the inner diameter arranged brake segments, each forming a partial braking surface. Thus, advantageous stick-slip effects between the brake ring and the pump shaft can be avoided.

On the one hand to allow easy mounting and on the other hand to obtain a defined bias between the brake ring and the pump shaft, the development of the invention is preferably carried out in which the brake segments are formed on a support ring to a component in which the brake segments laterally axially are arranged excellently on the carrier and in which the brake segments are held by a comprehensive spring ring on the circumference of the pump shaft. Thus, each of the brake segments is pressed uniformly over the spring ring on the circumference of the pump shaft, so that the Teilbrems- surfaces of the brake segments interact with the circumferential friction surface of the pump shaft.

For a subsequent integration of such a brake ring in a gear pump, the development of the invention is particularly suitable wherein the pump housing has a plurality of housing plates and a shaft housing, wherein the pump shaft is mounted in the outer housing plates and protrudes with the coupling end in the shaft housing and wherein the brake ring is arranged on a shaft portion of the pump shaft within the shaft housing. So it is possible to arrange the brake ring outside the housing plates.

For higher operating pressures in particular the development of the gear pump is suitable, in which within one of the housing plates and / or the shaft housing on the pump shaft, a shaft seal is provided which is assigned to the shaft portion of the pump shaft between a bearing and the brake ring. Thus, the functions between the sealing of the pump shaft and the deceleration of the pump shaft are clearly separated. The sealing surface formed on the circumference of the pump shaft can thus be formed and machined independently of the revolving friction surface. This way, each shaft section can be sealed to the relevant function or optimally adjusted to decelerate. In order to intercept as possible the internal pressure forces acting on the pump shaft in the interior of the pump housing relative to the brake ring, the development of the gear pump according to the invention is particularly advantageous in which a support bearing for radial and axial support of the pump shaft is formed within the shaft housing. For this purpose, the support bearing is assigned to the shaft section of the pump shaft between the brake ring and the coupling end.

In principle, it is also possible to arrange the brake ring on an outer side of the support bearing.

In order to increase the functionality of the brake ring with suitable materials even further, is provided according to an advantageous development that the brake ring at a distance from the braking surface has a circumferential sealing lip for sealing, on the circumference of the pump shaft is applied. Thus, the two functions braking the pump shaft and sealing the pump shaft can be combined with each other and run through a brake ring. In this way, it is advantageously possible to realize high tightnesses with respect to the coupling end of the pump shaft, wherein the brake ring and the shaft sealing ring form an annular space on the circumference of the pump shaft between them, which can be filled with a barrier liquid, so that an additional barrier is formed. In addition, deposits and aging processes of the pumped medium can be avoided by appropriate choice of barrier fluid. Thus, such gear pumps are particularly suitable for conveying and dosing of colored lacquers.

The gear pump according to the invention will be explained in more detail with reference to some embodiments with reference to the accompanying figures.

They show:

Fig. 1 shows schematically a cross-sectional view of a first embodiment of the gear pump according to the invention

Fig. 2 shows schematically a cross-sectional view of another embodiment of the gear pump according to the invention

Fig. 3 shows schematically a sectional view of a circumference of the pump shaft held brake ring

Fig. 4 shows schematically a cross-sectional view of another embodiment of the gear pump according to the invention

5 schematically shows a cross-sectional view of the pump shaft held on the brake ring of the embodiment of FIG .. 4

In Fig. 1, a first embodiment of the gear pump according to the invention is shown. The gear pump consists of a pump housing 1. The pump housing 1 is constructed in several parts and has a plurality of housing plates 1.1, 1.2 and 1.3 and a shaft housing 1.4. In- Within a central housing plate 1.3 a recess for two intermeshing gears 3 and 4 is included. The middle housing plate 1.3 is held with the gears 3 and 4 between the outer housing plates 1.1 and 1.2. In the end faces of the outer housing plates 1.1 and 1.2 each have a sealing ring 1.5 and 1.6 are arranged, through which the gaps between the middle housing plate 1.3 and the outer housing plates 1.1 and 1.2 are sealed to the outside.

One of the gears 3 is fixedly connected to a rotatable bearing shaft 6. The bearing shaft 6 is held in two bushings 6.1 and 6.2, which are embedded in the outer housing plates 1.1 and 1.2. The second gear 4 is rotatably held on a pump shaft 5. The pump shaft 5 is rotatably mounted with a plurality of shaft sections in the housing plates 1.1 and 1.2. For this purpose, the housing plate 1.1 has a first bearing bore 7.1 and the second housing plate 1.2 has a second bearing bore 7.2, in which the bearing bushes 8.1 and 8.2 are held. The bearing bore 7.1 is formed as a blind hole in the housing plate 1.1. In contrast, the bearing bore 7.2 in the housing plate 1.2 is continuous, so that the pump shaft 5 protrudes from the outer housing plate 1.2. The outside of the outer housing plate 1.2 projecting shaft portion of the pump shaft 5 forms a coupling end 5.1, on which a profiling 5.2 is formed. In the housing plate 1.2, a pump inlet 2 and a pump outlet not shown here is arranged, which form a conveyor channel system for the metered delivery of a flowable medium with the gears 3 and 4. The outside of the housing plate 1.2 outstanding shaft portion of the pump shaft 5 is surrounded by the shaft housing 1.4. The shaft housing 1.4 is for this purpose firmly connected to the housing plate 1.2. Within the shaft housing 1.4 a receiving bore 10 is formed, in which a coupling sleeve 9 is rotatably guided. The coupling sleeve 9 is connected at one end face on the profiling 5.2 with the pump shaft 5. On the opposite side, the coupling sleeve 9 has a profile opening to be coupled to a drive shaft of a drive. The coupling sleeve 9 is held by a locking ring 12 in the shaft housing 1.4, which has a receiving opening 13 in the axial extension of the coupling sleeve 9. Thus, the pump can be coupled via a plug connection with a drive.

On the side of the housing plate 1.2, the shaft housing 1.4 has a concentric with the pump shaft 5 arranged recess 31, in which a brake ring 11 is held against rotation. The brake ring 11 has at its inner diameter to a braking surface 11.1, which corresponds to a formed on the pump shaft 5 friction surface 5.3. The friction surface 5.3 is formed as a circumferential lateral surface on the circumference of the pump shaft 5. In the unloaded state, the inner diameter of the brake ring 11 relative to the outer diameter of the pump shaft 5 in the shaft portion of the friction surface 5.3 a defined undersize, so that the brake ring 11 exerts a contact pressure on the pump shaft 5. Upon rotation of the pump shaft 5, a braking torque is thereby generated via the brake ring 11.

In order to obtain a defined magnitude of the braking torque, the nature of the friction surface 5.3 on the pump shaft 5 and the nature of the braking surface 11.1 on the brake ring 11 and beyond the material of the brake ring 11 can be adapted to each other. Usually, the brake ring 11 is formed of a wear-resistant plastic.

For sealing the pump housing 1, a shaft sealing ring 14 is provided within the housing plate 1.2 in the region between the bearing bush 8.2 and the brake ring 11, which is assigned to the shaft portion of the pump shaft 5 between the bearing point and the friction surface 5.3. By the shaft seal 14 is between the housing plates 1.1, 1.2 and 1.3 formed conveyor channel system sealed to the outside in the area of the pump shaft 5.

In the embodiment of the inventive gear pump shown in FIG. 1, the pump shaft 5 is driven in operation via the coupling sleeve 9 by a coupled drive at a predetermined speed. In this state, the gears 3 and 4 engage each other and convey a supplied via the pump inlet 2 medium continuously to a pump outlet. In the event that an outlet pressure prevailing at the pump outlet is higher than an inlet pressure at the inlet side of the pump, a continuous flow through the gears 3 and 4 results for each revolution of the pump shaft 5. In the event that, due to pressure fluctuations, a reversal of the pressure difference acting between the pump inlet and the pump outlet occurs, additional hydraulic forces act on the gears 3 and 4, which act in the conveying direction. In this case, conditions may occur that a lead over the third party drive takes place, which has an effect in the context of the design-related Passungsspiele. In order to keep such operating conditions within narrow limits, a braking torque is generated continuously on the pump shaft 5 via the brake ring 11. The braking torque is designed such that a lead of the pump shaft relative to a drive shaft is prevented. Thus, unwanted load changes can be advantageously suppressed, so that no flow fluctuations during a rotation of the pump can occur. Due to the deceleration of the pump shaft 5 advantageously uniform flow rates are achieved even with fluctuating pressure conditions between the pump inlet and pump outlet. Depending on the design of the pump, different embodiments can be used for additional braking of the pump shaft. Thus, in the exemplary embodiment according to FIG. 1, it would also be possible for the brake ring 11 to be connected to the pump shaft 5 so as to be secure against rotation and to have an outer braking surface exposed to one in the shaft housing 1.4. formed friction surface cooperates. The friction surface on the shaft housing could be formed by a bore or flanks of a groove. In practice, however, the alternative variant of the invention has proven particularly useful in which the brake ring is held in a rotatable manner in a housing part.

2, a further embodiment of a gear pump according to the invention is shown, which is substantially identical to the embodiment of FIG. 1, so that only the differences are explained below and otherwise referred to the aforementioned description.

In the embodiment according to FIG. 2, the pump shaft 5 has a cylindrical coupling end 5.1, which protrudes from the shaft housing 1.4 and, for example, via a feather key with a drive can be coupled.

In a shaft portion between the coupling end 5.1 and a shaft seal 14 of the pump shaft 5, a brake ring 11 is assigned. The brake ring 11 is held against rotation in a recess 31 of the shaft housing 1.4.

For further explanation of the brake ring 11, reference is additionally made to FIG. 3 in addition to FIG. 3 shows a Schnittdar- position of the brake ring 11 on the circumference of the pump shaft 5. In this respect, the following description applies to both figures 2 and 3.

The brake ring 11 is formed in this embodiment by a support ring 15 and a plurality of laterally arranged on the support ring 15 brake segments 16. The carrier ring 15 and the brake segments 16 are combined to form a component, wherein the brake segments 16 are elastically connected to the carrier ring 15. The brake segments 16 protrude axially relative to the carrier ring 15 and are uniformly distributed over the circumference of the carrier ring 15. The individual brake 16 each have on an inner side a partial braking surface 16. 1 which rest on the circumference of the pump shaft 5 and interact with the friction surface 5. 3 of the pump shaft 5. In order to guide all brake segments 16 together on the circumference of the pump shaft 5, a spring ring 17 is provided, which spans the brake segments 16 and holds with a predefined bias on the circumference of the pump shaft 5. Due to the number of brake segments 16 held on the carrier ring 15 as well as the radial extent of the brake segments 16, additional parameters are given to generate certain braking characteristics on the pump shaft 5. In the illustrated embodiment, the circumferentially distributed brake segments 16 are formed identically and have in the radial direction at an equal distance from each other. Both the symmetrical arrangement of the brake segments and the distances between the brake segments can be distributed differently over the circumference.

The function of the embodiment shown in Fig. 2 is identical to the embodiment of FIG. 1, so that no further explanation at this point.

4, a further embodiment of a gear pump according to the invention is shown, as it is preferably used for metering paints in paint shops. In the embodiment of FIG. 4, the pump housing 1 is also formed in several parts. The gear 3 is rotatably held in this embodiment on a bearing pin 18 which is held in a pin bore 19 of the outer housing plate 1.1. Concentric with the bearing pin 18, a sealing ring 20 is arranged in the housing plate 1.1, through which the pin bore 19 is sealed to the outside.

The second gear 4 is held by a connecting means 21 directly on the circumference of the pump shaft 5. The axial gap which forms between the circumference of the pump shaft 5 and the gearwheel 4 is added to the sides of the gear 4 sealed by the O-rings 22.1 and 22.2. Thus, on the one hand penetration of the pumped medium into the gap between the gear 4 and the pump shaft 5 is avoided and on the other hand reaches a certain function of the connecting means 21 certain mobility of the gear 4 on the pump shaft 5. Thus, in particular caused by frontal start between the gear 4 and the housing plates 1.1 and 1.2 signs of wear can be advantageously evened out or reduced. The pump shaft 5 is mounted directly in the outer housing plates 1.1 and 1.2. In this case, no bushings are provided and the pump shaft 5 is guided directly into the bearing bores 7.1 and 7.2.

In addition, a plurality of flushing channels 23 are formed in the pump shaft 5, the housing plates 1.1 and 1.2 and the bearing pin 18 to completely rinse the interior of the pump housing 1 for the purpose of a delivery medium change. Such a flushing system for a gear pump is known for example from EP 1 164 293 A2, so that at this point reference can be made to the description given there and no further explanation is given here.

At the outside of the outer housing plate 1.2 outstanding shaft portion of the pump shaft 5, a shaft seal 14, a brake ring 11, and a support bearing 24 are formed between the coupling end 5.1 and the bearing. The shaft seal 14, the brake ring 11 and the support bearing 24 are held by the shaft housing 1.4 concentric with the pump shaft 5. The shaft housing 1.4 is for this purpose firmly connected to the housing plate 1.2. In the exemplary embodiment shown in FIG. 4, the brake ring 11 is likewise formed by a carrier ring 15 and a plurality of laterally molded brake segments 16.

To explain the brake ring 11 used in this embodiment, reference is also made to FIG. 5 in addition to FIG. In Fig. 5 is a cross-sectional view of the brake ring 11 is shown. As is apparent from Fig. 5, the support ring 15 at an inner diameter on a circumferential sealing lip 25. The sealing lip 25 is formed at a distance from the partial braking surfaces 16.1 of the brake segments 16 on the brake ring 11, so that the brake ring 11 performs a double function on the circumference of the pump shaft 5 in this case. On the one hand, the integrally formed on the support ring 15 brake segments 16 are pressed by a spring ring 17 to the friction surface 5.3 of the pump shaft 5 to generate a braking torque. At the same time, the carrier ring 15, with its sealing lip 25 running around the inside diameter, becomes adjacent to the friction surface 5.3 on the circumference of the pump shaft 5, forming a seal in the shaft housing 1.4 relative to the coupling end 5.1.

In the exemplary embodiment illustrated in FIG. 4, a closed annular space 26 is formed within the shaft housing 1.4 by the shaft sealing ring 14 and the brake ring 11. In the annular space 26 open channels 27 through which a barrier liquid can be introduced into the annulus. The channels 27 in the shaft housing 1.4 are closable, so that in the operating state, a barrier liquid can be held within the Ringrau- mes 26. As a barrier liquid, a solvent-containing fluid is preferably used as a function of the pumped medium in order to dissolve the leaked through gap leakage media, in this case paints within the annular space 29, so that hardening and sticking in the gaps are prevented.

The trained between the coupling end 5.1 and the brake ring 11 support bearing 24 is formed in this embodiment by a rolling bearing that is disposed between a shaft shoulder 28 of the pump shaft 5 and a housing shoulder 29 of the shaft housing 1.4. About the shaft shoulder 28 and the housing shoulder 29 can advantageously record axially acting forces on the pump shaft 5. Likewise, the forces acting from the outside over the coupling end 5.1 of the pump shaft 5 forces are intercepted by the support bearing 24 and not directed into the interior of the pump housing 1. The coupling end 5.1 of the pump shaft 5 is identical to the embodiment of FIG. 1 executed and carries the coupling sleeve 9. Here, the coupling sleeve 9 is held in the receiving bore 10 of the shaft lengehäuses 1.4 by a bearing sleeve 30, which at the same time a bearing point for a detachable drive shaft represents. In the drive shaft can be introduced via the receiving opening 13 at the end of the shaft housing 1.4 and connect via the coupling sleeve 9 with the pump shaft 5.

LIST OF REFERENCE NUMBERS

1 pump housing

1.1 outer housing plate

1.2 outer housing plate

1.3 middle housing plate

1.4 shaft housing

1.5 sealing ring

1.6 sealing ring

2 pump inlet

3 cogwheel (running)

4 gear (driven)

5 pump shaft

5.1 coupling end

5.2 profiling

5.3 Friction surface

6 bearing shaft

6.1, 6.2 Bearing bush

7.1, 7.2 Bearing bore

8.1, 8.2 Bushing

9 coupling sleeve

10 receiving hole

11 brake ring

11.1 braking surface

12 circlip

13 receiving opening

14 shaft seal

15 carrier ring

16 brake segments

16.1 partial braking surface

17 spring washer

18 journals

19 pin hole

20 sealing ring 21 connecting means

22.1, 22.2 O-ring

23 flushing channel

24 support bearings

25 sealing lip

26 annulus

27 channel

28 shaft shoulder

29 housing sales

30 bearing sleeve

31 recess

Claims

claims

Gear pump with a plurality of medium-meshing gears (3,4), which are rotatably supported in a pump housing (1), and with a pump shaft (5) for driving one of the gears (4), wherein the pump shaft (5) via a coupling end (5.1) can be coupled to a drive,

characterized in that

on the circumference of the pump shaft (5) a brake ring (11) is arranged, which acts with at least one braking surface (11.1) on a friction surface (5.3) of the pump shaft (5) or on a friction surface of the pump housing (1).

Gear pump according to claim 1,

characterized in that

the brake ring (11) is held against rotation in the pump housing (1.4) and that the braking surface (11.1) is formed on an inner diameter of the brake ring (11).

Gear pump according to claim 2,

characterized in that

the friction surface (5.3) of the pump shaft (5) is a peripheral circumferential surface, the outer diameter of which compared to the inner diameter of the brake ring (11) has an excess.

Gear pump according to claim 2 or 3,

characterized in that

the brake ring (11) has a plurality of brake segments (16) distributed uniformly distributed on the inner diameter, each of which forms a partial brake surface (16.1).

5. Gear pump according to claim 4,

characterized in that

the brake segments (16) are laterally axially excellently formed on a support ring (15) to form a component and that the brake segments (16) are held by a comprehensive spring ring (17) on the circumference of the pump shaft (5).

6. Gear pump according to one of claims 1 to 5,

characterized in that

the pump housing (1) has a plurality of housing plates (1.1, 1.2, 1.3) and a shaft housing (1.4), wherein the pump shaft (5) is mounted in two outer housing plates (1.1, 1.2) and connected to the coupling end (5.1) in the shaft housing ( 1.4) and wherein the brake ring (11) is arranged on a shaft portion of the pump shaft (5) within the shaft housing (1.4).

7. Gear pump according to claim 6,

characterized in that

within one of the housing plates (1.1, 1.2, 1.3) and / or the shaft housing (1.4) on the pump shaft (5) a shaft sealing ring (14) is provided, which a shaft portion of the pump shaft (59 between a bearing (7.2, 8.2) and the brake ring (11) is assigned.

8. Gear pump according to claim 6 or 7,

characterized in that

within the shaft housing (1.4) on the pump shaft (5) a support bearing (24) for radial and axial support of the pump shaft (5) is formed, which is a shaft portion of the pump shaft (5) between the brake ring (11) and the coupling end (5.1) assigned.

9. Gear pump according to one of claims 1 to 8, characterized in that

the brake ring (11) at a distance from the braking surface (1.1) has a circumferential sealing lip (25) for sealing, which rests on the circumference of the pump shaft (5).

10. Gear pump according to claim 9,

characterized in that

the brake ring (11) and the shaft seal (14) between them form an annular space (26) on the circumference of the pump shaft (5) and that the annular space (25) can be filled with a barrier liquid.