WO2002070898A1

WO2002070898A1 - Internal gear pump that does not contain any filler elements

Info

Publication number: WO2002070898A1
Application number: PCT/DE2002/000709
Authority: WO
Inventors: Reinhard Pippes; Stefan Bellemann
Original assignee: Eckerle Industrie-Elektronik Gmbh
Priority date: 2001-03-01
Filing date: 2002-02-28
Publication date: 2002-09-12
Also published as: US20030161748A1; KR20030011826A; DE10109769A1; JP2004518866A; EP1364126A1

Abstract

An internal gear pump that does not contain any filler elements comprises a housing (1) and a bearing ring (5), which is accommodated inside a recess (13) of the housing in a manner that permits it to transversally move in relation to its axis but not to rotate. The internal gear pump also comprises an internal-geared ring gear (3), which is mounted inside the bearing ring in a manner that permits it to revolve, and a pinion (2), which is mounted inside the housing in a manner that permits it to rotate and which meshes with said ring gear. The inner peripheral surface of the housing recess (13) coaxially extends in relation to the pinion (2), and the bearing ring, which is eccentrically arranged with regard to the pinion axis (15), can pivot in relation to the housing recess about a parallel pivotal axis (22, 23) that is parallel to the axis thereof. The bearing ring can pivot without the tight contact between the tooth tips of the pinion (2) and ring gear (3) being lost. The inner peripheral surface of the bearing ring (5) that forms the bearing surface for the ring gear (3) coaxially extends in relation to its outer peripheral surface (20), and the pivotal path of the bearing ring is delimited to a pre-designated measure by a pin (25), which passes therethrough or which is arranged in the sickle-shaped gap (21), or by a projecting step located inside this gap.

Description

Internal gear pump without filler

The invention relates to an internal gear pump with the features according to the preamble of patent claim 1.

An internal gear machine of this type is known (US-A 30 34 446). In it, the inner peripheral surface of the recess of the housing, in which the unit pinion / ring gear / bearing ring is received, is cylindrical and coaxial to the two bearing bores for the pinion and thus to the latter itself. Since the ring gear must be mounted eccentrically to the pinion, the inner circumferential surface of the bearing ring, which forms the bearing surface for the ring gear, is also eccentric to the pinion axis. The outer circumferential surface of the bearing ring, on the other hand, is formed eccentrically to this bearing surface, namely coaxially with the pinion shaft, so that the bearing ring as a whole is pivotally received in the housing recess with little radial play. Suction chamber and pressure chamber between the toothing of the pinion and ring gear are each delimited by housing inserts sealingly abutting the end faces of the pinion and ring gear, one of which is screwed or screwed onto an external thread of the pinion shaft and the other into an internal thread of the housing.

In terms of production technology, this design of the housing, the housing inserts and the bearing ring with circumferentially eccentric surfaces is complex because compliance with the high precision required in production, in particular at higher operating pressures, is very complex.

Internal gear pumps without fillers are also known with a pivotable bearing ring for the ring gear, the bearing surface and outer peripheral surface of which are concentric with one another and which is accommodated in the housing recess with little radial play (EP-A 848 165). However, this design of the bearing ring means that the inner circumferential surface of the housing recess is coaxial with the ring gear axis and consequently eccentric for the bearing of the pinion shaft. The consideration of this axis offset in the separate housing parts containing the bearing of the pinion shaft is also complex in terms of production technology.

In the non-meshing area of the gears, where only the tooth heads are in contact with each other, this type of gear machine is because of the small

Contact area the load and thus the wear relatively largest. If - as in the exemplary embodiments of EP-A 848 165 - the toothing of the pinion and ring gear is also involute toothing, their teeth are in mutual engagement only in the area of full engagement with their flanks and in the non-engagement area with their tooth tips sealing contact. In the remaining part of the suction chamber and pressure chamber, the teeth move away from each other to such an extent that essentially the same pressure prevails over the suction chamber and pressure chamber, and only approach each other again in the entry-free area in order to produce the sealing contact between the tooth heads. The hydraulic pressure forces prevailing in the pressure chamber act in such a way that their resultant produces a pivoting moment in relation to the pivot axis of the bearing ring, by means of which the portion assigned to the non-engagement region is pressed together with the ring gear radially towards the pinion axis. As a result, the heads of the teeth approaching one another in the non-engagement area run onto one another, whereby they are subject to a combined rolling and sliding process, which results in wear. It is therefore desirable to limit the sealing contact to a necessary but sufficient level at which the wear described above is minimal.

The object of the invention is therefore to reduce the manufacturing costs of the housing and the bearing ring without running the risk that the tooth tip wear through the sealing abutment of the tooth tips against each other in the non-engaging area of the toothing is excessive.

According to the invention, this object is achieved by the configuration according to patent claim 1. The fact that the unit pinion / ring gear / bearing ring

Housing recess runs concentrically or coaxially to the pinion and its bearing bores, the corresponding surfaces can be produced very economically in one clamping by turning operations. This also applies to the bearing ring, the bearing surface of which is concentric with the outer peripheral surface. As a result of the necessary eccentricity between the pinion and the ring gear, this design creates an uneven, namely crescent-shaped, increasing radial gap between the bearing ring and the housing recess. In particular on internal gear machines of the type discussed here, in which the teeth of the pinion and ring gear are involute teeth, the teeth are different

Trochoid toothings do not make sealing contact with each other during the entire revolution, but first diverge after full engagement and only in the non-engagement area of the toothing do the tooth heads of some teeth come into contact with the necessary sealing contact. There is therefore a risk of excessive wear of the tooth heads and thus a reduced service life of the machine if the tooth heads are pressed excessively against one another by the swiveling torque acting on the bearing ring in proportion to the pressure. This is prevented according to the invention in that the pressing force of the tooth tips against one another can be kept within limits by limiting the pivoting path of the bearing ring to a predetermined value.

Different possibilities are available for limiting the swivel path: According to one embodiment, a bore running approximately parallel to its axial direction can be provided in the bearing ring, through which a pin fixed in the housing protrudes with a play determining the swivel path. This pin can be designed as a spiral spring, which presses the bearing ring in the pivoting direction in the depressurized state of the internal gear pump, but prevents or hinders the bearing ring from further pivoting after being relieved by the predominant hydraulic pressure forces.

According to another embodiment, a stop pin can be placed in the crescent-shaped radial gap between the bearing ring and the housing recess from the bottom thereof protrude at which the bearing ring strikes after a certain swivel path. The stop pin can be fixed to the housing, for example at the bottom of the housing recess or on the bearing ring. The swivel path can be determined most precisely from the outset if this pin is arranged offset by approximately 90 ° with respect to the swivel axis of the bearing ring. In a further embodiment, the pivoting path of the bearing ring can be limited by a step which projects axially into the crescent-shaped radial gap between the bearing ring and the housing wall and which can be produced by means of a milling tool in the course of precision machining of the recess base. Since this base is worked out for the sealing contact of the end faces of the pinion and ring gear or corresponding axial plates thereon centrally to the ring gear axis, the step mentioned is given a contour corresponding to the crescent-shaped radial gap.

Further advantages and features of the invention emerge from the following description of exemplary embodiments with reference to the accompanying drawings and from the subclaims. The drawings show:

Figure 1 is an end view of the unit pinion / ring gear / bearing ring as a section along the line C - C in Figure 2.

2 shows a section along the line A - A in Figure 1;

3 as a detail on an enlarged scale, a partial section along the line B - B in FIG. 1, the axial plates being omitted;

4 shows a representation of a second embodiment analogous to FIG. 1;

5 shows a partial section along the line D - D in Figure 4;

6 shows a representation of a third embodiment analogous to FIG. 1, and

7 shows a partial section along the line E.-E in Fig.6. The internal gear pump shown in Figures 1 and 2 includes a whole

1 designated housing, which is constructed from a cup-shaped housing part 11 and a cup-shaped housing cover 12 fastened to the end face thereof. The housing 1 contains suction and pressure channels, not shown, which conduct the conveying liquid to and from the internal gear pump in the usual way.

In the housing 1, a pinion shaft 14 with an axis of rotation 15 is rotatably supported via slide bearings, not shown, and has a coupling part 16 on the right-hand end in FIG. 2 for engagement in the drive shaft of a drive motor, not shown. A pinion 2, which meshes with a ring gear 3, is formed in one piece on the pinion shaft 14. The ring gear 3 is widened on its outer circumference to form a race 4 and rotatably supported in a bearing ring 5 which is received in a housing recess 13. A bearing bush 6 made of a bearing metal is pressed into the bearing ring 5. On the end faces of the housing part 11 and the cover 12 on the one hand and on the end faces of the pinion

2 and ring gear 3, on the other hand, are sealing axial plates 8, which axially limit the tightly sealed suction and pressure chamber within the toothing of pinion 2 and ring gear 3 and connect them to the suction channel or the pressure channel by an opening (not shown).

1, the pinion 2 and the ring gear 3 are mounted relative to one another with an eccentricity e. This distance between the pinion axis 15 and the ring gear axis 18 corresponds to the theoretical tooth geometry of the pinion and ring gear and presupposes that the toothings roll and slide together without play. In the exemplary embodiment shown, the tooth flanks of the toothings are each designed as involute curves, ie there is involute toothing, the tooth heads being rounded in the non-engagement area to achieve a bump-free run-up and for the purpose of sealing. The number of teeth of the ring gear 3 differs from that of the pinion 2 by 1. The toothing meshes with one another in such a way that in FIG. 1 the teeth of pinion 2 engage fully in the tooth gaps of ring gear 3 and rest sealingly on the tooth flanks, while on the opposite side in FIG Tooth gaps of the ring gear 3 have emerged. In this engagement-free ring gear area, several of the tooth heads (in the exemplary embodiment three tooth heads each) are supported one after the other in the course of the rotation and thereby separate the suction chamber from the pressure chamber in the toothings.

In the exemplary embodiment shown, the housing recess 13 receiving the bearing ring 5 and the outer surface 17 of the housing part 11 with the radii R1 and R2 are machined concentrically with the pinion axis 15. The bearing surface 19 and the outer peripheral surface 20 of the bearing ring 5, however, are both concentric to the ring gear axis 18, which means that the outer peripheral surface 20 of the bearing ring 5 with its radius R3 is in turn eccentric to the housing recess 13 and with this a crescent-shaped radial gap

21 forms.

The wall of the recess 13 is partially penetrated by a bearing pin 22 which is pressed into the bottom of this recess. With the largely semi-cylindrical partial peripheral surface of the bearing pin protruding beyond the wall

22 this protrudes into an axial groove 23 of the bearing ring 5, which is adapted to the circular cylindrical cross section of the bearing pin 22. For the bearing ring 5, this bearing pin forms a pivot axis parallel to the axes of the pinion 2 and the ring gear 3, about which the bearing ring 5 can be pivoted in the recess 13. As can be seen from FIG. 1, this pivot axis is offset by approximately 80 ° in the direction of rotation indicated by the arrow in relation to the apex of the non-engaging region in which two tooth heads lie exactly opposite one another.

The bearing ring 5 has an offset parallel to the axes of rotation 15 and 18 parallel to the direction of rotation by approximately the same amount

Through hole 24 through which a pin 25 designed as a rod spring extends (FIG. 3). The bore 24 is offset from each shoulder to a shoulder, so that thereby a in the longitudinal center of the bore Ring projection 26 is created. The bore 24 opens at both ends in the region of a recess 28 in the housing or cover wall, which has a conically tapering bottom 30, which in turn merges into a housing bore 32 for supporting the bar spring 25. In this exemplary embodiment, the two housing bores 32 are aligned with one another and are offset radially with respect to the pinion axis 15 with respect to the bore 24. This results in the bending prestress of the bar spring 25 shown in FIG. 3, which rests with its longitudinal center on the contact projection 26 and consequently loads the bearing ring 5 with a spring force directed towards the pinion axis 15. Otherwise, the rod spring in the state shown in FIG. 3 runs contact-free through the bore 24 and the housing recesses 28. The support ends of the rod spring 25 are fixed in the housing bores 32; this passes through the part of the bore 24 formed by the contact projection 26 with a play which is predetermined according to the amount, the meaning of which is explained below.

The arrangement works as follows:

When the pinion 2 rotates in the direction of rotation shown by the arrow, the pumped medium is conveyed through the suction channel into the suction chamber (to the left in FIG. 1 from the line AA) between the teeth of the pinion 2 and the ring gear 3. The pumped medium is pressed out of the pressure chamber (to the right of line A - A in Fig. 1) with increased pressure through the pressure channel. Since the toothing of the pinion and ring gear is an involute toothing in the exemplary embodiment, its teeth are in mutual sealing contact only in the area of full engagement with their flanks and in the non-engagement area with their tooth heads. In the remaining part of the suction chamber and pressure chamber, the teeth move away from each other to such an extent that essentially the same pressure prevails over the suction chamber and the pressure chamber, and approach each other again in the entry-free area to produce the sealing contact between the tooth heads.

The hydraulic pressure forces prevailing in the pressure chamber act in such a way that their resultant produces a pivoting moment on the bearing ring 5 with respect to the pivot axis 22, by means of which this, more precisely: its non-engaging Area assigned section, together with the ring gear 3 is pressed radially toward the pinion axis 15. As a result, the heads of the teeth approaching one another in the non-engagement area run onto one another, whereby they are subject to a combined rolling and sliding process which results in wear. During this process, they are kept in mutual sealing contact in proportion to the pressure. Since this function is known from EP-A 848 165 mentioned at the outset, no further explanation is required here.

The prestressed bar spring 25 produces in the depressurized state, i.e. outside of the operation of the internal gear pump and in its start-up phase, approximately in the same direction as the pressure forces, a pivoting moment on the bearing ring 5 and thereby ensures that the toothing is correctly mutually connected and arranged, as well as for the required sealing contact, regardless of the occurrence of the hydraulic pressure forces in the non-invasive area. However, it is desirable to limit the sealing contact to just the necessary extent at which the wear described above is minimal. Therefore, the bias of the bar spring 25 is selected so that in the operating state of the internal gear pump, the hydraulic pressure forces alone ensure the sealing contact and the bar spring 25 is relieved and rests on the opposite side while consuming the play in the annular contact projection 26. In this position, the bar spring has a limiting effect on a further pivoting of the bearing ring 5 and thus relieves the tooth heads of a further contact pressure.

The embodiment according to FIGS. 4 and 5 differs from the previous one in that, instead of the bar spring 25, two stop pins 35 are pressed into the bottom of the housing recess 13 and protrude axially into the sickle-shaped annular gap 21, one of which is about 70 ° and the other another is offset by approximately 170 ° in the direction of rotation indicated by the arrow with respect to the pivot axis 22. The thickness of the stop pins 35 and their position are coordinated with respect to the local width of the annular gap 21 so that when the bearing ring 5 abuts the housing wall on one side, a predetermined one Distance to the circumferential surface 20 results, which defines the limited pivot path of the bearing ring 5.

In an embodiment, not shown, which is modified from the embodiment in FIGS. 4 and 5, the stop pins 35 can also be attached to or in the bearing ring 5 instead of being attached in the housing, e.g. welded or glued to the outer peripheral surface of the bearing ring 5, preferably received in an axially directed receiving groove in the peripheral surface of the bearing ring 5. In principle, a desired tolerance compensation can be set by appropriately selecting the diameter of the stop pin 35.

The embodiment according to FIGS. 6 and 7 has, as a swivel path limitation for the bearing ring 5, an axially protruding step 45 in the annular gap 21, which extends with the radius R4 concentrically to the ring gear axis and whose contour is aligned with the crescent-shaped annular gap. The annular gap 46 present between the step 45 and the outer surface 20 of the bearing ring 5 determines the total pivoting path of the bearing ring 5 on one side of the housing wall diametrically opposite the step 45.

In the embodiments according to FIGS. 4 to 7, the bearing ring 5 is acted upon solely by hydraulic pressure forces and the pivoting moment generated therefrom about the pivot axis 22 in order to maintain the sealing contact of the tooth heads in the entry-free area. It comes into contact with the stop pins 35 or the step 45 in the course of the pivoting movement, which then take over part of the pivoting moment and thereby the

Relieve tooth tips from a stronger contact pressure. In addition, this system prevents lifting of the bearing ring 5 from the pivot axis 22 and the resulting spinning of the bearing ring. In these embodiments, too, a bar spring of the type described above can additionally be provided, which either also contributes to limiting the pivoting path of the bearing ring or only ensures the sealing contact of the tooth heads in the unpressurized state of the pump in the pretensioned state.

Claims

claims

I. Internal gear pump without filler with a housing (1), one in one

Recess (13) of the housing can be moved transversely to its axis, but received a non-rotatably supported bearing ring (5), an internally toothed ring gear (3) mounted in the bearing ring and a pinion (2) rotatably mounted in the housing and meshing with the ring gear, the teeth of which by a full engagement in tooth gaps of the ring gear, on the one hand, and a sealing contact with the tooth heads of the ring gear in an engagement-free ring gear region approximately diametrically opposite the tooth gap engagement, on the other hand, define a suction space and a pressure space in the toothings, the inner

The circumferential surface of the housing recess (13) receiving the bearing ring (5) extends coaxially with the pinion (2) and the bearing ring lying eccentrically to the pinion axis (15) can be pivoted in this way relative to the housing recess about a pivot axis (22, 23) parallel to its axis that the sealing contact between the tooth tips of pinion

(2) and ring gear (3) is maintained, characterized in that the bearing surface (19) for the ring gear (3) forming the inner peripheral surface of the bearing ring (5) coaxial with its outer peripheral surface (20) and the pivoting path of the bearing ring is limited to a predetermined amount.

2. Internal gear pump according to claim 1, characterized in that the pivoting path is limited by a pin (25) which with predetermined

Play penetrates a bore in the bearing ring (25) approximately in its axial direction and is supported on the housing.

3. Internal gear pump according to claim 2, characterized in that the pin (25) is a bar spring which, in the depressurized state of the internal gear pump, loads the bearing ring in such a way that there is a sealing contact between the tooth heads of the pinion and ring gear in the non-engaging area of the toothings.

4. Internal gear pump according to claim 1, characterized in that the pivoting path is limited by at least one stop pin (35) in the crescent-shaped gap (21) between the outer peripheral surface

(20) of the bearing ring and the inner peripheral surface of the housing recess (13) is arranged.

5. Internal gear pump according to claim 4, characterized in that the stop pin (35) in the housing (1), preferably in the housing recess (13), or in or on the bearing ring (15)), preferably in the region of the outer circumference of the bearing ring (15 ) is attached.

6. Internal gear pump according to claim 5, characterized in that the stop pin (35), preferably axially parallel to the pinion axis in the bottom of the housing recess is attached.

7. Internal gear pump according to claim 5, characterized in that the stop pin is fastened in or on an outer peripheral surface of the bearing ring, preferably axially parallel to the axis of the bearing ring.

8. Internal gear pump according to one of claims 4 to 7, characterized in that the stop pin about 90 ° relative to the pivot axis (22) of the

Bearing rings is arranged offset.

9. Internal gear pump according to one of claims 4 to 8, characterized in that two stop pins are provided which are arranged offset by the same angle on both sides of the pressure chamber vertex.

10. Internal gear pump according to claim 1, characterized in that the pivot path through one of the bottom of the housing recess

(13) in the gap (21) between the bearing ring and the housing recess axially projecting step (45) is limited.

11. Internal gear pump according to claim 10, characterized in that the contour of the step is adapted to the gap and the step forms an annular gap (46) with the outer peripheral surface (20) of the bearing ring.