Internal gear pump

Abstract

An internal gear pump for forward and reverse operations, including: a pump housing which includes a first fluid port and a second fluid port, wherein in a first rotational direction, the first fluid port is formed as a fluid outlet and the second fluid port is formed as a fluid inlet, and in a second rotational direction, the first fluid port is formed as a fluid inlet and the second fluid port is formed as a fluid outlet; an internal gear and an external gear which together form delivery cells in order to deliver a fluid; a first rotary bearing which mounts the internal gear; and a second rotary bearing which mounts the external gear; and includes a lubricant feed which sets a fluid flow between the fluid ports through the two rotary bearings in both rotational directions.

Claims

1. An internal gear pump for forward and reverse operations, comprising: a pump housing which comprises a first fluid port and a second fluid port, wherein in a first rotational direction, the first fluid port is formed as a fluid outlet and the second fluid port is formed as a fluid inlet, and in a second rotational direction, the first fluid port is formed as a fluid inlet and the second fluid port is formed as a fluid outlet; an internal gear and an external gear which together form delivery cells in order to deliver a fluid; a first rotary bearing which mounts the internal gear; a second rotary bearing which mounts the external gear; and a lubricant feed which sets a fluid flow between the fluid ports through the two rotary bearings in both rotational directions, wherein a flow resistance between the first fluid port and the first rotary bearing is smaller than a flow resistance between the first fluid port and the second rotary bearing, and a flow resistance between the second fluid port and the second rotary bearing is smaller than a flow resistance between the second fluid port and the first rotary bearing.

2. The internal gear pump according to claim 1, wherein the lubricant feed comprises at least one channeling structure which exhibits a reduced flow resistance and which is provided in order to specifically guide the fluid along a flow path through the internal gear pump.

3. The internal gear pump according to claim 1, further comprising a base which axially delineates the delivery cells, wherein the lubricant feed comprises a channeling structure in the internal gear and a channeling structure in the base which are connected to each other fluidically.

4. The internal gear pump according to claim 3, wherein the channeling structure in the internal gear and/or the channeling structure in the base is/are formed as an axial passage opening.

5. The internal gear pump according to claim 3, wherein the base is fixedly connected to the external gear.

6. The internal gear pump according to claim 1, wherein the lubricant feed comprises a channeling structure which fluidically connects the first fluid port and the first rotary bearing to each other and a channeling structure which fluidically connects the second fluid port and the second rotary bearing to each other.

7. The internal gear pump according to claim 6, wherein the channeling structure which fluidically connects the first fluid port and the first rotary bearing to each other is arranged in an axial sealing gap which is formed on the internal gear, and/or the channeling structure which fluidically connects the second fluid port and the second rotary bearing to each other is arranged in an axial sealing gap which is formed on the external gear.

8. The internal gear pump according to claim 6, wherein the lubricant feed comprises a channeling structure, which extends in or through the first rotary bearing and is connected to the channeling structure which fluidically connects the first fluid port and the first rotary bearing to each other, and/or a channeling structure which extends in or through the second rotary bearing and is connected to the channeling structure which fluidically connects the second fluid port and the second rotary bearing to each other.

9. The internal gear pump according to claim 6, wherein at least one of the channeling structures s formed as a groove in the pump housing.

10. The internal gear pump according to claim 1, further comprising a third rotary bearing, which mounts the external gear, and/or a centering device which centers the external gear.

11. The internal gear pump according to claim 1, wherein the pump housing forms an axial sealing gap or an axial gap with the base.

12. The internal gear pump according to claim 1, wherein the lubricant feed comprises a channeling structure which is axially delineated by the base and the pump housing.

13. The internal gear pump according to claim 1, wherein the internal gear and/or the external gear is/are formed, at least in regions, from a magnetized material.

14. The internal gear pump according to claim 1, characterized by an electric coil for rotary-driving the internal gear and/or external gear.

15. The internal gear pump according to claim 3, wherein the base is formed integrally with the external gear.

16. The internal gear pump according to claim 1, wherein the lubricant feed lacks a channeling structure which fluidically connects the first fluid port and the second rotary bearing to each other and a channeling structure which fluidically connects the second fluid port and the first rotary bearing to each other.

17. The internal gear pump according to claim 1, wherein the internal gear and/or the external gear is/are formed, at least in regions, from a magnetized plastic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Features essential to aspects of the invention which can only be gathered from the figures can advantageously develop the subject-matter of aspects of the invention, individually or in combinations, and form part of the scope of the disclosure.

(2) The individual figures show:

(3) FIG. 1 an internal gear pump, in a longitudinal section;

(4) FIG. 2 a flow path of the lubricant when the internal gear pump is being driven in a first rotational direction;

(5) FIG. 3 a flow path of the lubricant when the internal gear pump is being driven in a second rotational direction which is opposite to the first rotational direction.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows an example embodiment of an internal gear pump 1 in accordance with an aspect of the invention. The internal gear pump 1 comprises a first fluid port 21 and a second fluid port 22. The internal gear pump 1 is a reversible pump which can be driven in a first rotational direction and in a second rotational direction which is different from the first rotational direction, i.e. the first fluid port 21 is a fluid inlet or a fluid outlet, depending on the rotational direction of the internal gear pump 1. The second fluid port 22 correspondingly forms the fluid outlet or the fluid inlet of the internal gear pump 1.

(7) From the fluid inlet into the pump 1, the fluid enters a pump space 3 through a pump chamber inlet and leaves the pump space 3 through a pump chamber outlet which is fluidically connected to the fluid outlet, i.e. to the first fluid port 21 or the second fluid port 22.

(8) The internal gear pump 1 has a pump housing or a housing 2 which forms the first fluid port 21 and the second fluid port 22. An internal gear 4 and an external gear 5 are arranged in the housing 2, wherein the external gear 5 is or can be connected to a drive in order to drive the internal gear pump 1. The external gear 5 is the drive gear and the internal gear 4 is the output gear. The internal gear 4 and the external gear 5 are respectively formed as a rotor. Additionally or alternatively, the internal gear 4 can be driven by means of a drive. It is in principle conceivable for the internal gear 4 or the external gear 5 to be formed as a stator.

(9) The external gear 5 is formed to be cup-shaped, comprising a base 8 which forms an axial end-facing wall of the pump space 3, i.e. the pump space 3 is delineated by the external gear 5 together with the housing 2 or, respectively, a lid of the housing 2.

(10) The internal gear 4 is arranged in the pump space 3, wherein a rotary axis of the internal gear 4 and a rotary axis of the external gear 5 extend parallel to each other but do not coincide, i.e. the internal gear 4 is mounted eccentrically in the pump chamber 3. The external gear 5 and the internal gear 4 are in engagement with each other and form delivery cells 3′ which transport the fluid from the pump space inlet to the pump space outlet, i.e. from the fluid inlet to the fluid outlet, wherein the delivery cells 3′ alter their volume due to the eccentric arrangement of the internal gear 4 with respect to the external gear 5, such that an increase in pressure in the fluid occurs as the fluid is transported through the pump space 3.

(11) The internal gear 4 has a central passage bore 42, and a passage opening 54 is formed in the base 8 of the external gear 5. A substantially circumferential cavity 7 is also formed in the housing 2, wherein an upper end-facing side of the external gear 5 cannot abut an internal wall of the housing 2 in the region of the cavity 7, such that no adhesion forces or friction forces between the external gear 5 and the housing 2 can occur in this region.

(12) In accordance with an aspect of the invention, the internal gear pump 1 comprises a lubricant feed which—independently of the rotational direction of the internal gear pump 1—sets a fluid flow which channels a lubricant, preferably a part of the fluid being delivered, through two rotary bearings D1, D2, wherein the first rotary bearing D1 mounts the internal gear 4 and the second rotary bearing D2 mounts the external gear 5. The first rotary bearing D1 is formed by a radial external side of the internal gear 4 and an internal surface of the housing 2 which lies opposite said radial external side. The second rotary bearing D2 is formed by a radial external side of the external gear 5 and an internal surface of the housing 2 which lies opposite said radial external side.

(13) In both rotational directions, the lubricant flows through the lubricant feed from the fluid outlet, the first fluid port 21 or the second fluid port 22, into a channeling structure 41, 51 which is formed in an axial sealing gap S1, S2 between the internal gear 4 and the housing 2 or between the external gear 5 and the housing 2. One of the axial sealing gaps—in this example embodiment, the axial sealing gap S2 which is formed between the external gear 5 and the housing 2—is enlarged in regions by the cavity 7, thus reducing friction, wherein one of the channeling structures—in this example embodiment, the channeling structure 51 which is formed in the axial sealing gap S2 between the external gear 5 and the housing 2—emerges into the cavity 7, such that the cavity 7 is filled with the lubricant. This further reduces friction. The lubricant is channeled in the channeling structures 41, 51, which are arranged in an axial sealing gap S1, S2, transverse to the rotational direction of the internal and external gears 4, 5.

(14) The channeling structures 41, 51 which are formed in an axial sealing gap S1, S2 are respectively adjoined by a channeling structure 41′, 51′ which is formed in a radial sealing gap or radial bearing gap between the internal gear 4 and the housing 2 or between the external gear 5 and the housing 2. The adjoining channeling structures 41′, 51′ are respectively formed in a rotary bearing D1, D2. These channeling structures 41′, 51′ channel the lubricant in an axial direction along a radial external side of the internal gear 4 or, respectively, the external gear 5. The channeling structure 41′ guides the lubricant through the first rotary bearing D1 for the internal gear 4 along the bearing surface, thus supplying the first rotary bearing D1 with the lubricant. The channeling structure 51′ guides the lubricant through the second rotary bearing D2 for the external gear 5 along the bearing surface, thus supplying the second rotary bearing D2 with the lubricant.

(15) Between the channeling structures 41′, 51′ which are formed in the radial sealing gap or radial bearing gap, the lubricant is channeled through the internal gear 4, the base 8 of the external gear 5, along the base 8 of the external gear 5, through a third rotary bearing and centering device D3 for the external gear 5, along the bearing and centering surface and through another axial sealing gap or axial gap S3 between the external gear 5 and the housing 2. The lubricant is guided through a channeling structure 42 in the internal gear 4, a channeling structure 54 in the base 8, a channeling structure 52 along the base 8, along the bearing and centering surface of the third rotary bearing and centering device D3 and along the other axial sealing gap or axial gap S3, whereby the lubricant can flow from the first rotary bearing D1 to the second rotary bearing D2 and vice versa. The channeling structure 42 in the internal gear 4 and the channeling structure 54 in the base 8 are respectively formed as a passage bore. The channeling structure 52 along the base 8 is formed as a gap S4 between the base 8 and the housing 2. The bearing and centering surface of the third rotary bearing and centering device D3, and the other axial sealing gap or axial gap S3, do not comprise any dedicated channeling structures in order to guide the lubricant. The lubricant flows due to leakage along the bearing and centering surface of the third rotary bearing and centering device D3 and along the other axial sealing gap or axial gap S3. In principle, the bearing and centering surface of the third rotary bearing and centering device D3 and/or the other axial sealing gap or axial gap S3 can comprise or form a channeling structure, for example a groove or a gap. The axial sealing gaps S2, S3 between the external gear 5 and the housing 2 are formed on opposite axial sides of the external gear 5.

(16) The third rotary bearing and centering device D3 of the external gear 5 projects annularly from the lower end-facing side of the external gear 5 and extends parallel to the rotary axis of the external gear 5. The external gear 5 is formed in a twin-cupped shape. On the first axial side of the external gear 5, the external gear 5 comprises a first cup space in which the internal gear 4 is arranged or into which the internal gear 4 protrudes. On the second axial side of the external gear 5, the external gear 5 comprises a second cup space in which a part of the housing 2 is arranged or into which the housing 2 protrudes, for rotationally mounting and/or centering.

(17) It follows from the above that the flow path for the lubricant through the internal gear pump 1 is identical, irrespective of the rotational direction in which the gears 4, 5 are rotated; only the flow direction of the lubricant changes with the rotational direction of the internal gear pump 1.

(18) A channeling structure can be embodied as a groove or cavity, wherein the groove or cavity is preferably formed in the housing 2, since the housing 2 is in principle designed as a stator. Depending on the manner in which the housing 2 is produced, the groove or cavity is latterly introduced into the housing 2 or is cast, injection-molded, sintered, printed, etc. together with the housing 2. In this example embodiment, the channeling structures 41, 41′, 51, 51′ are formed as grooves. Alternatively, a channeling structure can be embodied as a gap which is formed or delineated by arranging at least two components at a distance from each other. In this example embodiment, the channeling structure 52 is formed as a gap 54. If a leakage flow is sufficient for the flow of lubricant, channeling structures can be omitted. An amount of the lubricant can be influenced by configuring the respective channeling structure, for example its depth, width, profile, etc.

(19) The first axial sealing gap S1 is formed axially between the internal gear 4 and the housing 2. The channeling structure 41 is arranged in the first axial sealing gap S1 and connects the first axial sealing gap S1 to the first fluid port 21 and/or to the delivery cells 3′ connected to the first fluid port 21. When the first fluid port 21 is arranged on the pressure side of the internal gear pump 1 and therefore forms a fluid outlet (the first rotational direction), lubricant flows through the channeling structure 41 into the first axial sealing gap S1 and on to the first rotary bearing D1, thus supplying the first rotary bearing D1 with lubricant. When the first fluid port 21 is arranged on the suction side of the internal gear pump 1 and therefore forms a fluid inlet (the second rotational direction), lubricant flows through the channeling structure 41 from the first axial sealing gap S1 to the first fluid port 21 and/or to the delivery cells 3′ connected to first fluid port 21. The first axial sealing gap S1 lacks a channeling structure connecting the first axial sealing gap S1 to the second fluid port 22 and/or to the delivery cells 3′ connected to the second fluid port 22. This ensures that in the first rotational direction, the lubricant does not flow directly from the first rotary bearing D1 to the second fluid port 22, which is formed as a fluid inlet, via the first axial sealing gap S1, but rather flows to the second fluid port 22 circuitously through the internal gear 4, the base 8 and the second rotary bearing D2.

(20) The second axial sealing gap S2 is formed axially between the external gear 5 and the housing 2. The channeling structure 51 is arranged in the second axial sealing gap S2 and connects the second axial sealing gap S2 to the second fluid port 22 and/or to the delivery cells 3′ connected to the second fluid port 22. When the second fluid port 22 is arranged on the pressure side of the internal gear pump 1 and therefore forms a fluid outlet (the second rotational direction), lubricant flows through the channeling structure 51 into the second axial sealing gap S2 and on to the second rotary bearing D2, thus supplying the second rotary bearing D2 with lubricant. When the second fluid port 22 is arranged on the suction side of the internal gear pump 1 and therefore forms a fluid inlet (the first rotational direction), lubricant flows through the channeling structure 51 from the second axial sealing gap S2 to the second fluid port 22 and/or to the delivery cells 3′ connected to second fluid port 22. The second axial sealing gap S2 lacks a channeling structure connecting the second axial sealing gap S2 to the first fluid port 21 and/or to the delivery cells 3′ connected to the first fluid port 21. This ensures that in the second rotational direction, the lubricant does not flow directly from the second rotary bearing D2 to the first fluid port 21, which is formed as a fluid inlet, via the second axial sealing gap S2, but rather flows to the first fluid port 21 circuitously through the second rotary bearing D2, the base 8 and the internal gear 4.

(21) The axial sealing gap S5 is formed axially between the internal gear 4 and the base 8 of the external gear 5. In both rotational directions, the axial sealing gap S5 separates the channeling structure 42 in the internal gear 4 and the channeling structure 54 in the base 8 from the pump space 3 and/or the delivery cells 3′, thus preventing lubricant from flowing from the channeling structures 42, 54 to the pump space 3 and/or delivery cells 3′ and from the pump space 3 and/or delivery cells 3′ to the channeling structures 42, 54.

(22) The channeling structures 41, 41′ are formed on the pump housing 2. The internal gear 4 and the pump housing 2 form the first axial sealing gap S1. The channeling structure 41 is arranged in the region of the pump housing 2 in which the first axial sealing gap S1 is formed. The channeling structure 41 is open towards the first axial sealing gap S1. The first axial sealing gap S1 is arranged radially between the delivery cells 3′ and the first rotary bearing D1. The first axial sealing gap S1 is arranged radially between the fluid ports 21, 22 and the first rotary bearing D1. Via the first axial sealing gap S1, the channeling structure 41 establishes a fluidic connection between the first fluid port 21 and/or the delivery cells 3′ connected to the first fluid port 21 and the first rotary bearing D1. A corresponding connection (via a groove or the like) between the second fluid port 22 and the first rotary bearing D1 is not provided.

(23) The channeling structure 41′ is formed in the first rotary bearing D1, in particular a slide bearing. The internal gear 4 and the pump housing 2 form a radial sealing gap or radial bearing gap in the first rotary bearing D1. The channeling structure 41′ is arranged in the region of the pump housing 2 in which the radial sealing gap or bearing gap is formed. The channeling structure 41′ is open towards the radial sealing gap or bearing gap. The channeling structure 41 and the channeling structure 41′ emerge into each other. Via the axial sealing gap S1 and the radial sealing gap or bearing gap and/or the rotary bearing D1, the channeling structures 41, 41′ establish a fluidic connection between the first fluid port 21 and the channeling structure 42 in the internal gear 4. A corresponding connection (via a groove or the like) between the second fluid port 22 and the channeling structure 42 in the internal gear 4 is not provided. The channeling structure 41′ can also be omitted.

(24) The channeling structures 51, 51′ are formed on the pump housing 2. The external gear 5 and the pump housing 2 form the second axial sealing gap S2. The channeling structure 51 is arranged in the region of the pump housing 2 in which the second axial sealing gap S2 is formed. The channeling structure 51 is open towards the second axial sealing gap S2. The second axial sealing gap S2 is arranged radially between the pump space 3 or the delivery cells 3′ and the second rotary bearing D2. The second axial sealing gap S2 is arranged radially between the fluid ports 21, 22 and the second rotary bearing D2. Via the second axial sealing gap S2, the channeling structure 51 establishes a fluidic connection between the second fluid port 22 and/or the delivery cells 3′ connected to the second fluid port 22 and the second rotary bearing D2. A corresponding connection (via a groove or the like) between the first fluid port 21 and the second rotary bearing D2 is not provided.

(25) The channeling structure 51′ is formed in the second rotary bearing D2, in particular a slide bearing. The internal gear 4 and the pump housing 2 form a radial sealing gap or radial bearing gap in the second rotary bearing D2. The channeling structure 51′ is arranged in the region of the pump housing 2 in which the radial sealing gap or bearing gap is formed. The channeling structure 51′ is open towards the radial sealing gap or bearing gap. The channeling structure 51 and the channeling structure 51′ emerge into each other. The second channeling structure 51′ can also be omitted.

(26) The external gear 5 and the pump housing 2 form the other axial sealing gap S3. The other axial sealing gap S3 is arranged radially between the second rotary bearing D2 and the third rotary bearing D3. A channeling structure can be formed in the other axial sealing gap S3, and a channeling structure can also be formed in the third rotary bearing and centering device D3. The pump housing 2 comprises at least the channeling structure 41 and the channeling structure 51.

(27) The pump housing 2 comprises a first housing part 2′ and a second housing part 2″. The first housing part 2′ comprises or forms the first rotary bearing D1 and the second rotary bearing D2. The first housing part 2′ also comprises or forms the first axial sealing gap S1 with the internal gear 4 and the second axial sealing gap S2 with the external gear 5. The first housing part 2′ also comprises or forms the fluid ports 21, 22 and seals the pump space 3 on its end-facing side. The second housing part 2″ comprises or forms the third rotary bearing and centering device D3. The second housing part 2″ protrudes into the second cup space of the external gear 5, for mounting and/or centering the external gear 5. The second housing part 2″ also comprises or forms the other axial sealing gap S3 with the external gear 5.

(28) The internal gear pump 1 also comprises an electric coil 6 which is arranged on the outside of the housing 2 and surrounds the third rotary bearing and centering device D3 outside the housing 2. The external gear 5 consists entirely or at least in regions of a magnetized material. The external gear 5 consists entirely or at least in regions of a magnetized plastic.

(29) The magnetized material consists of a plastic in which magnetized particles, preferably soft iron particles, are embedded. Magnetic and electrical properties can be specifically set by the proportion, shape and distribution of the magnetized particles in the plastic.

(30) The magnetized material is magnetized in such a way that the external gear 5 can be rotary-driven by the electric coil 6. The external gear 5 is driven in the first rotational direction or the second rotational direction, depending on the supply of current passed through the coil 6.

(31) The magnetized material is also magnetized in such a way that the external gear 5 is axially pressed and/or pushed against at least the second axial sealing gap S2 by the electric coil 6, thus axially compensating the sealing gap S2, wherein the external gear 5 is pressed and/or pushed against the axial sealing gap S5 and the internal gear 4 is thereby pressed and/or pushed against the first axial sealing gap S1, thus axially compensating the sealing gap S1. The channeling structure 41 in the first sealing gap S1 and the channeling structure 51 in the second sealing gap ensure that a particular amount of lubricant can flow through the axial sealing gaps S1, S2, even when the sealing gaps S1, S2 are axially compensated by corresponding magnetization.

(32) The magnetized material can in principle be magnetized in such a way that the external gear 5 is magnetically centered with respect to the pump housing 2 by the electric coil 6. The magnetic centering device can also be set by permanent magnets, for example when the pump 1 is driven mechanically, wherein the electric coil 6 is replaced with one or more permanent magnets.

(33) FIG. 2 shows the lubricant path in the first rotational direction. In the first rotational direction, the first fluid port 21 is arranged on the pressure side of the internal gear pump 1 and therefore formed as a fluid outlet or pressure port, and the second fluid port 22 is arranged on the suction side of the internal gear pump 1 and therefore formed as a fluid inlet or suction port. FIG. 3 shows the lubricant path in the second rotational direction. In the second rotational direction, the second fluid port 22 is arranged on the pressure side of the internal gear pump 1 and therefore formed as a fluid outlet or pressure port, and the first fluid port 21 is arranged on the suction side of the internal gear pump 1 and therefore formed as a fluid inlet or suction port.

(34) In the first rotational direction, a first lubricant flow from the first fluid port 21 to the second fluid port 22 is set by the lubricant feed, as shown in FIG. 2. In this case, the lubricant feed comprises the following flow paths:

(35) a first flow path which extends radially through the first axial sealing gap S1 or along the first axial sealing gap S1, between the internal gear 4 and the pump housing 2, to the first rotary bearing D1. The first flow path extends along the channeling structure 41 to the first rotary bearing D1.

(36) a second flow path which extends axially through the first rotary bearing D1 or along the first rotary bearing D1. The second flow path extends along the channeling structure 41′.

(37) a third flow path which extends axially through the internal gear 4. The third flow path extends along or through the channeling structure 42 in the internal gear 4.

(38) a fourth flow path which extends axially through the base 8. The fourth flow path extends through or along the channeling structure 54 in the base 8.

(39) a fifth flow path which extends radially along the base 8. The fifth flow path extends through or along the axial gap S4 formed between the base 8 and the pump housing 2. The fifth flow path extends along the channeling structure 52 which is axially delineated by the base 8 and the pump housing 2.

(40) a sixth flow path which extends through or along the third rotary bearing and centering device D3. The lubricant feed can comprise a channeling structure, which extends through or along the third rotary bearing and centering device D3, for the sixth flow path. The channeling structure can comprise a groove in a radial sealing gap, which is formed between the external gear 5 and the pump housing 2, and/or a radial/axial gap which is formed between the external gear 5 and the pump housing 2. The channeling structure can be axially and/or radially delineated by the external gear 5 and the pump housing 2.

(41) a seventh flow path which extends radially through or along the other axial sealing gap S3, between the external gear 5 and the pump housing 2, to the second rotary bearing D2.

(42) an eighth flow path which extends axially through or along the second rotary bearing D2. The eighth flow path extends along the channeling structure 51′.

(43) a ninth flow path which extends radially through or along the second axial sealing gap S2, between the external gear 5 and the pump housing 2, to the second fluid port 22. The ninth flow path extends along the channeling structure 51 to the second fluid port 22.

(44) If the internal gear pump 1 does not comprise a third rotary bearing and centering device for the external gear 5, then the sixth flow path is omitted.

(45) In the second rotational direction, a second lubricant flow from the second fluid port 22 to the first fluid port 21, which extends back along the flow path of the first lubricant flow, is set by the lubricant feed.