Gerotor Pump And Motor/Pump Unit

Abstract

A gerotor pump for conveying a fluid from an inlet pump chamber which is connected to an inlet to an outlet pump chamber, which is connected to an outlet, of the gerotor pump having a rotatable outer rotor; a rotatable inner rotor, which is arranged radially inside the outer rotor; a housing having a housing cover and a housing base, between which the outer rotor and the inner rotor are arranged; and at least one compensation plate which is arranged in each case axially between the outer rotor and inner rotor and the housing cover or the housing base, wherein the at least one compensation plate in the idle state of the gerotor pump is axially spaced apart from the outer rotor and the inner rotor by pretensioning.

Claims

1. A gerotor pump for conveying a fluid from an inlet pump chamber which is connected to an inlet to an outlet pump chamber, which is connected to an outlet, of the gerotor pump having: a rotatable outer rotor; a rotatable inner rotor which is arranged radially inside the outer rotor; a housing having a housing cover and a housing base, between which the outer rotor and the inner rotor are arranged; and at least one compensation plate which is arranged in each case axially between the outer rotor and inner rotor and the housing cover or the housing base, wherein the at least one compensation plate in the idle state of the gerotor pump is axially spaced apart from the outer rotor and the inner rotor by pretensioning.

2. The gerotor pump as claimed in claim 1, having, as the at least one compensation plate, an upper compensation plate which is arranged axially between the outer rotor and inner rotor and the housing cover and/or a lower compensation plate which is arranged axially between the outer rotor and inner rotor and the housing base.

3. The gerotor pump as claimed in claim 2, having at least one resilient element which pretensions the upper compensation plate axially with respect to the housing cover and/or which pretensions the lower compensation plate axially with respect to the housing base.

4. The gerotor pump as claimed in claim 3, having the upper compensation plate and the lower compensation plate, wherein the at least one resilient element is arranged axially between the upper and the lower compensation plate.

5. The gerotor pump as claimed in claim 1, wherein the at least one compensation plate has at least one inlet through-hole which is connected in fluid terms to the inlet and at least one outlet through-hole which is connected in fluid terms to the outlet.

6. The gerotor pump as claimed in claim 1, wherein the at least one compensation plate has at least one first groove which extends on a housing-cover-side end face or on a housing-base-side end face at least along a circumference of the compensation plate.

7. The gerotor pump as claimed in claim 6, wherein the at least one first groove extends in at least one radial portion of the compensation plate radially from the circumference to the radial center of the compensation plate.

8. The gerotor pump as claimed in claim 1, wherein the at least one compensation plate has at least one pump chamber groove which extends at a rotor-side end face and which together with intermediate spaces between the inner rotor and the outer rotor defines the inlet pump chamber or the outlet pump chamber.

9. The gerotor pump as claimed in claim 8, having at least one compensation seal which is arranged at a housing-cover-side or a housing-base-side end face of the at least one compensation plate and which encloses a compensation face which is axially opposite the pump chamber groove, wherein a face enclosed by the pump chamber groove is smaller than the compensation face.

10. A motor/pump unit having: a gerotor pump as claimed in claim 1; and a motor which is connected to the inner rotor and which is configured to rotate the inner rotor in order to operate the gerotor pump.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0031] Other details, advantages and features of the present invention will be appreciated from the following description of exemplary embodiments with reference to the drawings, in which:

[0032] FIG. 1 shows a schematic cross sectional view of a gerotor pump according to an embodiment of the present invention;

[0033] FIG. 2 shows a perspective view of a compensation plate of the gerotor pump according to the embodiment of the present invention;

[0034] FIG. 3 shows a schematic sectioned view of the gerotor pump according to the embodiment of the present invention; and

[0035] FIG. 4 shows a schematic block diagram of a motor/pump unit according to another embodiment of the present invention.

[0036] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0037] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0038] FIG. 1 shows a schematic cross sectional view of a gerotor pump 1 according to a first embodiment of the present invention.

[0039] The gerotor pump 1 is configured and constructed to convey a fluid from an inlet pump chamber which is connected to an inlet 2 to an outlet pump chamber, which is connected to an outlet 3, of the gerotor pump 1.

[0040] In FIG. 1, arrows 28 indicate the exemplary fluid flow for explanation. The gerotor pump 1 has a rotatable outer rotor 4 and a rotatable inner rotor 5, wherein the inner rotor 5 is arranged radially inside the outer rotor 4. A radial direction 26 is illustrated in FIG. 1. The inner rotor 5 is connected to a shaft 25 which drives the inner rotor 5 during operation of the pump 1. An idle state is defined as no torque being applied by the shaft 25.

[0041] Furthermore, the gerotor pump 1 has a housing 8 having a housing cover 6 and a housing base 7, wherein the inner rotor 5 and the outer rotor 4 are arranged axially between the housing cover 7 and the housing base 7. An axial direction 27 is indicated in FIG. 1.

[0042] The gerotor pump 1 has in the present embodiment two compensation plates 9. In this instance, the gerotor pump 1 has an upper compensation plate 10 between the outer rotor 4 and inner rotor 5 and the housing cover 6 and a lower compensation plate 11 between the outer rotor 4 and inner rotor 5 and the housing base 7. The gerotor pump 1 of the present invention is, however, not limited thereto but instead may have only the upper compensation plate 10 or only the lower compensation plate 11.

[0043] The compensation plates 10, 11 are pretensioned by resilient elements 12, in this instance helical springs. In this instance, the upper compensation plate 10 is pretensioned in the direction toward the housing cover 6 and the lower compensation plate 10 is pretensioned in the direction toward the housing base 7. In an exemplary case, in which only one of the compensation plates 10, 11 is present, the resilient element 12 bears on the corresponding opposing housing cover 6 or housing base 7.

[0044] The resilient elements 12 result in the compensation plates 10, 11 in the idle state of the gerotor pump 1 being axially spaced apart from the outer rotor 4 and the inner rotor 5 by the pretensioning of the resilient elements 12. The friction between the compensation plates 10, 11 and the rotors 4, 5 is thereby reduced so that the gerotor pump 1 requires a small start-up torque.

[0045] The resilient elements 12 bring about the above-mentioned axial spacing between the compensation plates 10, 11 (or the respective compensation plate 10, 11 with respect to the opposing housing base 7 or housing cover 6), in particular in the idle state of the gerotor pump 1. During operation of the gerotor pump 1, in particular at higher pressures, the compensation plates 10, 11 are pressed toward each other by the pressurized fluid. In other words, during operation of the gerotor pump 1, the upper compensation plate 10 is pressed in the direction toward the housing base 7 and/or the lower compensation plate 11 is pressed in the direction toward the housing cover 6. This is explained below.

[0046] FIG. 2 shows a perspective view of a compensation plate 9 of the gerotor pump 1 according to the present embodiment. FIG. 2 shows in particular the upper compensation plate 10, wherein the explanations below can alternatively or additionally describe the lower compensation plate 11 (in particular transposed with reference to the axial direction 27). Furthermore, the explanations above and below relate to a recovery gerotor pump which can be operated in a bidirectional manner. However, the invention may also be used for a unidirectional gerotor pump. In this instance, the axial compensation is preferably carried out only at one side from the high-pressure side or low-pressure side, in particular only at the high-pressure side. In other words, only the left half of the gerotor pump 1 illustrated in FIG. 1 may have the structures described, whilst the right half (low-pressure side or tank pressure side) may be configured in accordance with a conventional gerotor pump. In this instance, the compensation plate 10 illustrated in FIG. 2 may also be substantially halved with respect to its circumference. In other words, in place of a 360 configuration illustrated (circular), the compensation plate 10 may comprise approximately 160 or more, preferably approximately 180 or more, more preferably 190 or more, preferably no more than 270 (part-circular). Naturally, a geometric form other than circular may also be selected, depending on the provisions.

[0047] As can be seen in FIG. 2, the compensation plate 10 has an end face 16. With respect to the upper compensation plate 10, the end face 16 is a housing-cover-side end face 16 (cf. FIG. 1). The compensation plate 10 has a groove 15 which extends at the housing-cover-side end face 16 along a circumference 18 of the compensation plate 10. As a comparison of FIG. 2 with FIG. 1 shows, the lower compensation plate 11 has the first groove 15 at a housing-base-side end face 17. As can further be seen in FIG. 2, the groove 15 extends in a radial portion 19 of the compensation plate 10 radially from the circumference 18 to the radial center 20 of the compensation plate 10. The shaft 25 illustrated in FIG. 1 extends through the radial center 20 of the compensation plate 10.

[0048] It is thereby possible for pressurized fluid which reaches a region between the upper compensation plate 10 and the housing cover 6 or between the lower compensation plate 11 and the housing base 7, to be able to return back to the shaft 25 and consequently back to the inner rotor 5 or outer rotor 4. In this instance, the radial center 20 of the compensation plate 10 can receive the shaft 25 with a clearance fit so that fluid can flow through the radial center 20 (radially) between the shaft 25 and compensation plate 10 in an axial direction 27.

[0049] Furthermore, the compensation plate 10 has in the present embodiment two inlet through-holes 13 which are connected in fluid terms to the inlet 2. Furthermore, the compensation plate 10 has in this instance two outlet through-holes 14 which are connected in fluid terms to the outlet 3.

[0050] A recess 29 of the compensation plate 10 as illustrated in FIG. 2 is configured to receive a locking pin (not illustrated) which prevents the compensation plate 10 from being rotated during operation of the pump 1.

[0051] FIG. 2 further illustrates resilient element recesses 40 which in each case receive a resilient element 12.

[0052] The compensation plate(s) 10 (upper and/or lower) may further have a plurality of the grooves 15 described above, for example, one on each of the end faces 16, 17 of the compensation plate(s) 10. In such an exemplary case, the two grooves 15 may be connected in fluid terms by at least one axially extending groove of the compensation plate(s) 10. A pressure compensation between both sides of the compensation plate(s) 10 can thereby be achieved so that axial pressure forces on them can be reduced or minimized.

[0053] In FIG. 1, the inlet through-holes 13 and the outlet through-holes 14 are illustrated with broken lines for the upper compensation plate 10.

[0054] FIG. 3 is a schematic sectioned view of the gerotor pump 1 according to the present embodiment. The sectioned view of FIG. 3 shows in particular a plan view in the axial direction 27 with a transparent housing cover 6.

[0055] As can be seen in FIG. 3, the gerotor pump 1 has according to the present embodiment a pump chamber groove 21 for the inlet pump chamber and a pump chamber groove 21 for the outlet pump chamber. These pump chamber grooves 21 are formed in the rotor-side end face 22 of the compensation plate 10 (illustrated with broken lines). The lower compensation plate 11 may also have these pump chamber grooves 21. The pump chamber grooves 21 define together with intermediate spaces between the inner rotor 5 and outer rotor 4 the inlet pump chamber and the outlet pump chamber (in each case).

[0056] As the sectioned illustration of FIG. 1 shows, these pump chamber grooves 21 are arranged axially opposite, in particular axially directly opposite, compensation seals 23 (or the enclosed faces thereof. The compensation seals 23, which are illustrated in FIG. 3, enclose compensation faces which are axially opposite the corresponding pump chamber grooves 21. The compensation face which is enclosed by the compensation seal 23 and the pump chamber groove 21 are connected in fluid terms by the corresponding inlet through-holes 13 or outlet through-holes 14.

[0057] The pressurized fluid flows from the inlet pump chamber (from the corresponding pump chamber grove 21) through the inlet through-hole 13 into a compensation space 30 enclosed by the compensation seal 23 in the housing cover 6 or in the housing base 7. This is illustrated in FIG. 1.

[0058] As shown in particular by a comparison of FIG. 1 with FIG. 3, the compensation face which is enclosed by the compensation seal 23 is greater than a face enclosed by the pump chamber groove 21. Since the fluid in the pump chamber groove 21 has the same pressure as the fluid in the compensation space 30, and the compensation face is greater than the face enclosed by the pump chamber groove 21, the pressurized fluid applies a greater force to the compensation face than to the pump chamber groove 21 (P=F/A; F=P*A). Consequently, an overall force which counteracts the pretensioning by means of the resilient elements 12 is produced.

[0059] In other words, the compensation plates 10, 11 during operation of the pump 1 are pressed axially toward the inner rotor 5 and the outer rotor 4, whereby the axial gap is reduced at higher pressures. The degree of efficiency of the gerotor pump 1 thereby increases for higher pressures. At lower pressures, as a result of the pretensioning of the compensation plates 10, 11, the viscous friction is reduced and consequently a start-up torque of the gerotor pump 1 is also reduced. These are in particular achieved by suitable adaptation of the compensation face.

[0060] FIG. 4 shows a schematic block diagram of a motor/pump unit 100 according to an embodiment of the present invention.

[0061] The motor/pump unit 100 has a motor 101 and a gerotor pump 1 according to the present invention. The motor 101 is configured to rotate the inner rotor 5 in order to operate the gerotor pump 1. In this instance, the motor 101 is mechanically connected to the inner rotor 5 by the shaft 25 (see further FIG. 1). The motor/pump unit 100 has a degree of efficiency and a particularly long service-life.

[0062] In addition to the above written description of the invention, for additional disclosure reference may explicitly hereby be made to the illustrated drawings of the invention in the Figures.

[0063] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

[0064] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

TABLE-US-00001 List of reference numerals 1 Gerotor pump 2 Inlet 3 Outlet 4 Outer rotor 5 Inner rotor 6 Housing cover 7 Housing base 8 Housing 9 Compensation plate 10 Upper compensation plate 11 Lower compensation plate 12 Resilient element 13 Inlet through-hole 14 Outlet through-hole 15 Groove 17 End face 18 Circumference 19 Radial portion 20 Radial center 21 Pump chamber groove 22 Rotor-side end face 23 Compensation seal 25 Shaft 26 Radial direction 27 Axial direction 28 Fluid flow 29 Recess 30 Compensation space 40 Resilient element recess