HIG-OUTER ROTOR SHADOW POCKETS

Abstract

A gerotor pump comprises an outer gerotor with an opening formed by an inner surface thereof, an inner gerotor accommodated within the opening of the outer gerotor, wherein a plurality of cavities are formed between the inner gerotor and the outer gerotor, and a plurality of first pockets, each of the first pockets being formed as a depression in the inner surface of the outer gerotor. Each of the first pockets forms a first pressure relief feature to prevent overpressure in each of the cavities formed between the outer gerotor and the inner gerotor.

Description

[0001] The invention relates to a gerotor pump, and in particular a gerotor pump with a pressure relief feature to prevent axial separation between an outer gerotor and a housing of the gerotor pump.

[0002] A gerotor pump is a type of internal rotary positive displacement pump in which an inner rotor (gerotor) located within an outer rotor (gerotor) is used to pump a fluid, such as a lubricating oil, through the interaction between the inner and outer gerotors during their mutual rotation. The inner gerotor comprises outwardly extending teeth configured to engage with inwardly extending teeth of the outer gerotor to transmit rotary motion between them. The axes of rotation of the inner and outer gerotors are offset from each other, and the inner gerotor has one fewer tooth than the outer gerotor, resulting in the continuous formation of continuously changing cavities between the inner surface of the outer gerotor and the outer surface of the inner gerotor.More precisely, these cavities first expand in size when a tooth of the inner gerotor begins to retract from a recess between adjacent teeth of the outer gerotor, thus expanding the space between them. Subsequently, these cavities contract in size when the tooth of the inner gerotor finally begins to enter another recess of the outer gerotor, thus contracting the space between them. A suction pressure resulting from the described expansion of the cavities draws the fluid into the expanding cavities on an inlet side of the gerotor pump, while the compression of the fluid resulting from the contraction of the cavities pumps the fluid out of the gerotor pump on an outlet side.

[0003] One disadvantage identified with regard to such gerotor pumps concerns the variable axial forces acting on the outer gerotor during different operating modes of the gerotor pump. The effects of such variable forces are summarized with reference to an example configuration of a gerotor pump 1, as described in Fig. Figure 1 shows the gerotor pump 1 with respect to each of a plurality of different circumstances A - G that occur successively during the operation of the gerotor pump 1. Referring to the graph from Fig. 2 corresponds to each of the specified circumstances A - G a combination of the instantaneous flow rate and instantaneous pressure of the pumped fluid passing through the gerotor pump 1 while the gerotor pump 1 is undergoing an operating cycle. In the part relevant to this explanation, the gerotor pump 1 comprises a casing wall 2 with an inner surface 2a, an outer gerotor 3 with a rim 3a configured to engage with the inner surface 2a, and a shaft 4 extending through the outer gerotor 3 and defining an axis of rotation thereto. The shaft 4 is partially contained within a cylindrical sleeve 5 extending axially inward from the inner surface 2a of the casing wall 2, and the casing wall 2 further comprises an inlet opening 6 and an outlet opening 7 formed on opposite sides of the sleeve 5 and the shaft 4, respectively.An end of the shaft 4 opposite the sleeve 5 can be axially restricted by a housing section 8 facing the corresponding end of the shaft 4. Although not shown, continuous cavities are formed around the circumference between the inner surfaces of the outer gerotor 3 and the outer surfaces of an inner gerotor (not shown) accommodated within the outer gerotor 3, with the pumped fluid entering such cavities axially through the inlet opening 6 and then exiting such cavities in the opposite axial direction through the outlet opening 7.

[0004] One problem related to the disclosed configuration of the example gerotor pump 1 concerns the way in which the pumped fluid typically enters such fluid-receiving cavities formed in the outer gerotor 3 while flowing in only one axial direction through the inlet opening 6 and an open end of the outer gerotor 3. As shown with reference to circumstance A, which corresponds to the gerotor pump 1 at the time of its initial start-up, a magnetic force acting on the outer gerotor 3 normally forces the outer gerotor 3 and the shaft 4 into an inclined configuration in which only a portion of the rim 3a of the outer gerotor 3 engages with the inner surface 2a of the casing wall 2.The force of the pumped fluid entering the outer gerotor 3 through the inlet opening 6 and striking an axial end surface 3b in the outer gerotor 3 also contributes to this inclination of the outer gerotor 3 and the shaft 4, as disclosed with reference to the illustration of circumstance A. This inclination of the outer gerotor 3 further leads to the generation of frictional forces between an outer surface of the shaft 4 and an inner surface of the sleeve 5, as well as to the formation of an axial gap between the inner surface 2a and the edge 3a in the direction of the inlet side of the gerotor pump 1 and at a position diametrically opposite the contact point between them on the outlet side of the gerotor pump 1.

[0005] As explained with reference to the description of circumstance B, an increase in the internal pressure forces applied by the pumped fluid to the axial end surface 3b of the outer gerotor 3 leads to a separation of the entire rim 3a from the inner surface 2a if neither a counter-pressure force against the outer gerotor 3 in the direction of the inner surface 2a nor the frictional forces existing between the shaft 4 and the sleeve 5 are large enough to counteract the internal pressure forces acting against the counter-pressure and the frictional forces. This can lead to a significant increase in the axial distance between the rim 3a and the inner surface 2a, allowing pumped fluid to escape around an entire portion of the rim 3a. The excessive forces of circumstance B can also cause the shaft 4 to come into undesirable frictional contact with the housing section 8 after axial movement of the shaft 4 away from the housing wall 2.

[0006] As shown with reference to the illustration of circumstance C, the counter-pressure applied to the outer gerotor 3 can eventually counteract the internal pressure forces to such an extent that a partial reduction of the axial distance is necessary, resulting in reduced discharge. As shown with reference to the illustration of circumstance D1, the counter-pressure forces eventually overcome the internal pressure forces, so that only the nominal skew of the outer gerotor 3 contributes to the formation of a relatively small distance and the re-engagement of at least a section of the rim 3a with the inner surface 2a, while the outer gerotor 3 transitions to rotation in a more parallel arrangement, which may include the elimination of frictional forces between the shaft 4 and the inner surface of the sleeve 5.As shown in the other descriptions of circumstances E - G, fluctuations in the internal pressure forces caused by the entry of the pumped fluid into the cavities via the inlet opening 6, and fluctuations in the formation of opposing counter-pressure forces, can each lead to fluctuations in the inclination of the outer gerotor 3 and the maximum axial distance that exists between the edge 3a and the inner surface 2a, with reference to the in . Fig. 2 disclosed, different operating conditions of the gerotor pump 1 lead to, for example, when the gerotor pump 1 is controlled from the normal operating condition E back into a switch-off state which corresponds to a return to condition A, as in each case with reference to Fig. 1 and Fig. 2 revealed.

[0007] A negative consequence of the axial separation of the outer gerotor 3 from the inner surface 2a of the housing wall 2 is that excessive and undesirable amounts of the pumped fluid can escape around the edge 3a, resulting in flow losses with respect to the gerotor pump 1. This effect was found to be particularly pronounced when the example gerotor pump 1 is operated at relatively high speeds (>3000 rpm), relatively low pressures (<1 bar), and with a (pumped) fluid temperature between 20 and 120 degrees Celsius.The axial separation of the outer gerotor 3 from the inner surface 2a also leads to a possible rotation of the outer gerotor 3 about an axis that is considerably inclined relative to its intended axis of rotation (as shown, for example, in circumstances A, B, C, F, and E). This contributes to the potential occurrence of wear where such surfaces engage with each other in a rotating manner and generate frictional forces between them. Such axial separation can also lead to the occurrence of wear at other locations in the gerotor pump 3, for example, where the shaft 4 meets the housing section 8, during periods in which a particularly large axial distance is maintained.

[0008] It would therefore be desirable to provide an improved gerotor pump with a pressure relief feature suitable for preventing the separation of the outer gerotor from a corresponding seating surface and the resulting excessive leakage of the pumped fluid from the outer gerotor and / or wear of the gerotor pump due to component misalignment as a result of such separation, wherein such a pressure relief feature is configured to provide such pressure relief by reducing the axially applied internal pressure forces that occur in the fluid-receiving cavities formed between the inner gerotor and the outer gerotor of the improved gerotor pump.

[0009] The object of the present invention is to create a gerotor pump with improved characteristics.

[0010] This problem is solved by a gerotor pump according to claim 1.

[0011] As disclosed, an improved gerotor pump with a pressure relief feature was surprisingly developed.

[0012] According to an embodiment of the present invention, a gerotor pump comprises an outer gerotor with an opening formed by an inner surface thereof, an inner gerotor received in the opening of the outer gerotor, wherein a plurality of cavities are formed between the inner gerotor and the outer gerotor, and a plurality of first pockets, each of the first pockets being formed as a depression in the inner surface of the outer gerotor. Each of the first pockets forms a first pressure relief feature to prevent overpressure in each of the cavities formed between the outer gerotor and the inner gerotor.

[0013] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 Several different circumstances A - G that occur in a conventional gerotor pump, leading to leakage and pumping losses of a pumped fluid; Fig. 2. a graph showing the conditions that determine each of the Fig. The circumstances shown in section 1 correspond to A - G; Fig. 3 a cross-sectional view through a central plane of a gerotor pump according to an embodiment of the present invention; Fig. 4 a front elevation showing an isolated housing of the gerotor pump; Fig. 5. A rear view of the gerotor pump housing; Fig. 6 a cross-sectional view showing an inlet opening and an outlet opening of the housing from the perspective of section lines 6-6 in Fig. 4 shows; Fig. 7 an enlarged view of a section from Fig. 5 to illustrate a boundary line shape of the inlet opening and the outlet opening of the housing; Fig. 8 a right-side perspective view showing an isolated arrangement of an outer gerotor and shaft of the gerotor pump; Fig. 9 a frontal view of the arrangement Fig. 8, showing the inner surfaces of the outer gerotor; Fig. 10 an enlarged view of a bounded section of the outer gerotor, as in Fig. 9 indicated; Fig. 11 and Fig. 12 cross-sectional views of the gerotor pump from the perspective of the section line 11, 12 - 11, 12 from Fig. 3, wherein Fig. 11 shows a relationship that exists between the outer gerotor and an inner gerotor at a first time point, and Fig. 12 shows a relationship that exists between the outer gerotor and an inner gerotor at a second time point after the first time point; Fig. 13 and Fig. 14 cross-sectional views of the gerotor pump from the perspective of section line 13, 14 - 13, 14 from Fig. 3, wherein Fig. 13 shows a relationship that exists between the outer gerotor, the inner gerotor, the inlet opening of the housing and the outlet opening of the housing at a first time point, and Fig. 14 shows a relationship that exists between the outer gerotor, the inner gerotor, the inlet opening of the housing and the outlet opening of the housing at a second time point which is after the first time point.

[0014] The following description of the technology is merely exemplary of the subject matter, manufacture, and use of one or more inventions and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in any other application filed claiming priority to this application, or in patents arising from such. In the disclosed methods, the sequence of steps shown is exemplary, so the sequence of steps may differ in various embodiments. The use of "a" or "an" indicates that "at least one" of the elements is present; where possible, several such elements may be present.Unless explicitly stated otherwise, all numerical data in this description are to be understood as being modified by "approximately," and all geometric and spatial descriptors are to be understood as being modified by "essentially," in order to describe the broadest possible range of application. "Approximately" in the context of numerical data indicates that the calculation or measurement allows for a slight degree of inaccuracy in the value (with some degree of approximation to the accuracy of the value; approximately or fairly close to the value; almost). If, for any reason, the inaccuracy indicated by the expressions "approximately" and / or "essentially" is not otherwise understood in this ordinary sense within the field, then, as used in this document, "approximately" and / or "essentially" indicate at least variations resulting from ordinary methods of measurement or the use of such parameters.

[0015] All documents, including patents, patent applications, and scientific literature, cited in this detailed description are incorporated herein by reference unless expressly stated otherwise. In the event of any conflict or ambiguity between a document incorporated herein by reference and the detailed description, the present detailed description shall prevail.

[0016] Although the open term “exhibit” is used herein as a synonym for non-restrictive terms such as comprehensive, containing or exhibiting to describe and claim embodiments of the present technology, embodiments may alternatively be described using terms with more restrictive meanings such as “consisting of” or “essentially consisting of”.Thus, for all embodiments in which materials, components or process steps are listed, the present technology specifically includes those embodiments that consist of or essentially consist of such materials, components or process steps, thereby excluding additional materials, components or processes (in the case of consisting of) and additional materials, components or processes that influence the significant properties of the embodiment (in the case of essentially consisting of), even though such additional materials, components or processes are not explicitly listed in this application.For example, listing a composition or process in which elements A, B and C are listed may specifically provide embodiments which consist of A, B and C and are essentially identical, while excluding an element D that may be listed in the field, although element D is not explicitly listed as excluded therein.

[0017] Disclosures of ranges referenced herein, unless otherwise stated, include the endpoints and encompass all distinct values ​​and further subdivided ranges within the full range. Thus, for example, a range "from A to B" or "from about A to about B" includes A and B. Disclosures of values ​​and ranges of values ​​for specific parameters (for example, quantities, proportions of weight, etc.) do not exclude other values ​​and ranges of values ​​that might be useful herein. It is understood that two or more expressly exemplified values ​​for any parameter represent the endpoints of a range of values ​​that may be claimed for the parameter. For example, if parameter X is exemplified herein with the value A and also exemplified with the value Z, it is understood that parameter X may have a range of values ​​from about A to about Z.Similarly, it can be assumed that the disclosure of two or more ranges of values ​​for a parameter (regardless of whether these ranges are nested, overlapping, or separate) subsumes all possible combinations of ranges of that value that can be claimed using the disclosed ranges. For example, if the parameter X is specified herein by way of example with values ​​in the ranges 1-10, 2-9, or 3-8, it can likewise be assumed that the parameter X may have other ranges of values ​​including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, etc.

[0018] When an element or layer is described as "at," "interacting with," "connected with," or "coupled with" another element or layer, it may be directly at, interacting with, connected with, or coupled to that other element or layer, or there may be intervening elements or layers. Conversely, when an element is described as "directly at," "directly interacting with," "directly connected with," or "directly coupled with" another element or layer, there should be no intervening elements or layers. Other terms used to describe the relationship between elements should be interpreted similarly (e.g., "between" as opposed to "directly between," "adjacent" as opposed to "directly adjacent," etc.).The term “and / or” used herein includes any and all combinations of one or more of the items listed.

[0019] Although the terms "first," "second," "third," etc., may be used herein to describe multiple elements, components, areas, layers, and / or sections, these elements, components, areas, layers, and / or sections should not be restricted by these terms. These terms are generally used only to distinguish one element, component, area, layer, or section from another. Terms such as "first," "second," and other numerical terms, when used in this document, do not imply any sequence or order unless explicitly stated by the context.Thus, a first element, a first component, a first area, a first layer or a first section listed below could also be referred to as a second element, a second component, a second area, a second layer or a second section, without departing from the teachings of the exemplary embodiments.

[0020] Spatial terms such as "inside," "outside," "below," "under," "lower," "above," "upper," and similar terms may be used herein to simplify the description when describing the relationship of an element or feature to one or more other elements or features, as illustrated in the figures. Spatial terms may be intended to encompass orientations of the device during use or operation beyond the orientation shown in the figures. For example, if the device in the figures is inverted, elements described as "below" or "underneath" other elements or features would be "above" them. Thus, the exemplary term "below" can include an orientation both above and below.The device can also be oriented differently (rotated by 90 degrees or in other orientations), and the descriptions used herein with spatial reference may be interpreted accordingly.

[0021] Fig. Figures 3-14 show a gerotor pump 10 with at least one internal pressure relief feature according to an embodiment of the present invention. The gerotor pump 10 comprises, as far as relevant to the disclosure of the present invention, a housing 11, an outer gerotor 20, an inner gerotor 40, a shaft 60, and a casing 70. The housing 11 includes a connecting wall 12 in which fluid connections for conveying a pumped liquid to and from the gerotor pump 10 are provided. The connecting wall 12 includes an inlet opening 16 and an outlet opening 17, each extending to an inner surface 12a of the connecting wall 12. A shaft sleeve 13 extends axially inward from the inner surface 12a and forms a cylindrical opening 13a for rotatably receiving a first end section of the cylindrically shaped shaft 60.As with reference to the isolated views of a (front) segment of the housing 11 in . Fig. As can be seen in Figures 4-7, which includes the formation of the connecting wall 12 at its front end, the inlet opening 16 is formed on one diametric side of the sleeve 13, and the outlet opening 17 is formed on the opposite second diametric side of the sleeve 13. The spacing of the openings 16 and 17 is accordingly in a lateral direction of the gerotor pump 10, i.e., in a direction extending into the blade with reference to the cross-sectional view. Fig. Figure 3 shows a perspective from a plane that lies directly between the openings 16 and 17 with respect to the lateral direction. The orientation of the openings 16 and 17 relative to the rest of the gerotor pump 10 also becomes clear with reference to the illustration of an operating procedure for the gerotor pump 10, as described in the Fig. 13 and Fig. 14 are shown, which are described in more detail below.

[0022] The casing 70 has an essentially cylindrical shape and comprises an open axial end forming a rim 70a configured to extend to and engage with the inner surface 12a of the connecting wall 12. The casing 70 defines a hollow opening in the gerotor pump 10 that accommodates the outer gerotor 20, the inner gerotor 40, and the shaft 60, respectively. The hollow opening at the open end of the casing 70 is axially bounded by the inner surface 12a and by the inner surface of the casing 70 along a closed axial end. The closed axial end of the casing 70 may include a shaft opening 72 configured to rotatably receive a second end section of the shaft 60 opposite the rotatable reception of the shaft 60 in the shaft sleeve 13.

[0023] The outer gerotor 20 can be axially subdivided into a fluid intake section 21 and a drive component section 22, each having a substantially cylindrical shape. The fluid intake section 21 is formed by an axial end section of the outer gerotor 20, which is open at the end and configured to face and cover the inlet opening 16 and the outlet opening 17 on the inner surface 12a of the connecting wall 12, thus allowing the pumped fluid to flow axially into and out of the fluid intake section 21 by passing through the connecting wall 12. The open axial end of the fluid intake section 21 forms a rim 23 of the outer gerotor 20, which is configured to normally face the inner surface 12a of the connecting wall 12 and thus engage at positions surrounding the inlet and outlet openings 16 and 17.The drive component section 22 comprises components associated with the operation of a drive mechanism 99 configured to drive the rotation of the gerotors 20, 40. The drive mechanism 99 may include electrical and / or magnetic components corresponding to a conventional electric motor arrangement or the like, operating in a conventional manner, so that a specific description of the drive mechanism 99 is omitted here. It should also be noted that the drive mechanism 99 need not necessarily be in the form of an electric motor to remain within the scope of the present invention, since the advantageous relationships disclosed herein are not dependent on the drive method for the gerotor pump 10. That is to say, any drive mechanism for driving the engagement between the gerotors 20, 40 in the manner described may be within the scope of the present invention.

[0024] A backpressure chamber 75 is formed between an outer axial end surface of the outer gerotor 20 and an inner axial end surface of the casing 70. The backpressure chamber 75 is configured to receive portions of the pumped fluid that either exit the outer gerotor 20 or are directed to the backpressure chamber 75 via an inlet passage 18 and / or an outlet passage 19.In the present embodiment, the inlet passage 18 is formed by an opening through the connecting wall 12, which lies radially between the edge 70a of the casing 70 and the edge 23 of the outer gerotor 20, in order to communicate fluidically with the cylindrical shape formed between them, while the outlet passage 19 is formed by an opening through the housing 11, which extends from a surface defining the outlet opening 17 through the connecting wall 12 and to a position between the edge 23 of the outer gerotor 20 and the edge 70a of the casing 70. Although the outlet passage 19 is not shown directly relative to the positions of the edges 23, 70a, it can be seen from the view through the Fig. 4 - 7, that the passages 18, 19 are equidistant from a central axis of the outer gerotor 20 and therefore both would be arranged relative to the edges 23, 70a in the same way as in Fig. Figure 3 shows the inlet passage 18. The liquid taken up in the counter-pressure chamber 75 exerts a pressure force on the outer gerotor 20 in a direction in which its edge 23 is forced towards the inner surface 12a of the connecting wall 12, thereby preventing liquid from escaping around the edge 23.

[0025] The outer gerotor 20, and in particular its fluid receiving section 21, comprises an opening formed by an inner surface of the fluid receiving section 21. The inner surface of the fluid receiving section 21 is formed by the interaction of an inner circumferential surface 24 and a base surface 28 thereof. The inner circumferential surface 24 extends around the circumference of the fluid receiving section 21 and extends axially from the edge 23 of the outer gerotor 20 to the base surface 28 of the outer gerotor 20. The base surface 28 is arranged perpendicular to the axial direction of the outer gerotor 20 and faces the inner surface 12a of the connecting wall 12 and is positioned opposite it.The inner circumferential surface 24 is toothed around its circumference to form a corrugated profile shape with an alternating arrangement of teeth 25 and recesses 26 in its circumferential direction, each of the teeth 25 extending radially inward from a substantially cylindrically contoured segment of the inner circumferential surface 24 curved about a central axis of the outer gerotor 20, and each of the recesses 26 being formed by one of the substantially cylindrically contoured segments arranged between adjacent teeth 25. Each of the teeth 25 may, as desired, form an arc of a circular segment radially inward from the cylindrical contours forming the recesses 26 along the course of the individual teeth.However, alternative wavy gear-like configurations of the teeth 25 and the recesses 26 can be used to form the inner circumferential surface 24 instead of those shown and described, without departing from the scope of the present invention.

[0026] The inner gerotor 40 is received in the opening of the outer gerotor 20 and extends axially from a first axial end surface 41, configured to face and engage with the inner surface 12a of the connecting wall 12, to a second axial end surface 42, configured to face and engage with the base surface 28 of the outer gerotor 20. Each of the axial end surfaces 41, 42 may have a substantially planar configuration. The inner gerotor 40 further comprises an outer circumferential surface 43 that connects the axial end surfaces 41, 42 around a periphery of the inner gerotor 40. The outer circumferential surface 43 is configured to engage with the inner circumferential surface 24 of the outer gerotor 20 via a gear-like transmission of the rotary motion during the rotation of the gerotors 20, 40.The outer circumferential surface 43 is toothed around its circumference to form a corrugated profile shape with an alternating arrangement of teeth 45 and recesses 46 in its circumferential direction, each of the teeth 45 extending radially outward relative to one of two adjacent and surrounding recesses 46. Each of the teeth 45 comprises a profile shape substantially similar to that of the respective recesses 26 of the outer gerotor 20, while each of the recesses 46 comprises an arc-shaped profile shape substantially similar to that of the respective teeth 25 of the outer gerotor 20.The teeth 45 of the outer gerotor 40 can have a shape that is essentially identical to each of the recesses 26, except that a radial outermost section of the same is cut off such that a radial spacing exists between the radial outermost surface of each of the recesses 26 and the radial outermost surface of each of the teeth 45 when the respective tooth 45 is received to the maximum extent in the respective of the recesses 26, so that a relatively small flow space may remain between the teeth 45 and the recesses 26 even when maximally inserted into them.

[0027] The axis of rotation of the outer gerotor 20 is defined by the central axis of the shaft 60, while the axis of rotation of the inner gerotor 40 is defined by the central axis of a cylindrically shaped outer circumferential surface 13b of the sleeve 13, so that the axes of rotation of the outer and inner gerotors 20, 40 are offset from each other in a direction perpendicular to the extension directions of the axes, which in the present figures is the perpendicular direction.The inner gerotor 40 also includes one fewer tooth 45 than the outer gerotor 20 includes, which, in combination with the offset axes of the gerotors 20, 40, provides the ability to form variably shaped and dimensioned cavities 55 between the inner circumferential surface 24 of the outer gerotor 20 and the outer circumferential surface 43 of the inner gerotor 40 during the rotation of the respective gerotors 20, 40, thereby causing a pumping action of the gerotor pump 10 during the uniform rotation of both gerotors 20, 40 relative to the housing 11.

[0028] As a comparison of Fig. 11 and Fig. 12 evident, which the gerotors 20, 40 at a first time ( Fig. 11) and then at a second time ( Fig. 12) After a slight rotation of the respective gerotors 20, 40 in the indicated direction (clockwise from the perspective shown between the first and second points in time), in typical operation of the gerotor pump 10, the rotation of the respective gerotors 20, 40 results in the removal of one of the cavities 55 formed towards the inlet opening 16, which contains one of the teeth 45 of the inner gerotor 40, from the interior of a corresponding recess 26 of the outer gerotor 20, so that the corresponding cavity 55 expands in size to allow the pumped liquid to flow through the inlet opening 16 and into the cavity 55 in an axial direction.As this cavity 55 moves circumferentially around the periphery of the inner circumferential surface 24 towards the lateral side of the gerotor pump 10, which has the outlet opening 17, one of the teeth 45 of the inner gerotor 40 begins to engage one of the recesses 26 of the outer gerotor 20 and essentially fill it, thus compressing and pressurizing the fluid contained in the cavity 55. The pressurized fluid then escapes from the cavity 55 by flowing axially beyond the edge 23 of the outer gerotor 20 and passing through the outlet opening 17 of the connecting wall 12, where the outlet opening 17 intersects the inner surface 12a.

[0029] As described in the "Background" section of this disclosure, the process of compressing the pumped fluid in such cavities 55 can lead to conditions in which the internal pressure forces resulting from the compression of the fluid can separate the edge 23 of the outer gerotor 20 from the inner surface 12a of the connecting wall 12, since such forces act away from the connecting wall 12 and against the back pressure generated in the counter-pressure chamber 75. This can lead to excessive leakage of the pumped fluid beyond the edge 23, thus reducing the flow rate through the gerotor pump 10.As a solution to this problem, the present invention is characterized by the inclusion of at least one pressure relief feature in the gerotor pump 10, whereby a maximized pressure that occurs in each of the cavities 55 formed between the gerotors 20, 40 can be advantageously reduced by the formation of additional volumes and / or pressure-equalizing flow paths within the gerotor pump 10, which can be occupied and / or flowed through by the compressed fluid.

[0030] According to a first pressure relief feature, the base surface 28 of the outer gerotor 20 comprises a plurality of pockets 30 formed therein. As in Fig. As shown in Figure 3, the pockets 30 are each formed as an axially recessed section of the base surface 28. In the present embodiment, this includes the fact that the pockets 30 are each recessed axially into the base surface 28 in the direction of the counter-pressure chamber 75, relative to an adjacent flat surface of the base surface 28 that engages with the second axial end surface 42 of the inner gerotor 40. Thus, during the movement of the gerotors 20 and 40 relative to each other, the surface forming the respective pockets 30 is spaced apart from the second axial end surface 42 of the inner gerotor 40 and does not engage directly with it. As a non-limiting example, the distance of the axial recess of the pockets 30 relative to the adjacent flat surface of the base surface 28 can be approximately 4 mm.Each of the pockets 30 can comprise a boundary shape and size suitable for allowing a portion of the fluid contained in each of the cavities 55 to flow, at a time during the movement of the corresponding cavity 55 around the periphery of the outer gerotor 20, as caused by the relative movement between the inner and outer gerotors 20, 40, into an adjacent cavity 55 by passing along and through one of the pockets 30 between the second axial end surface 42 of the inner gerotor 20 and the recessed surface forming the corresponding pocket 30, along the base surface 28, which is axially spaced from the second axial end surface 42.

[0031] Each of the pockets 30 can generally be associated with a corresponding recess 26 and can therefore extend such that it covers most or all of the base surface 28 at the corresponding recess 26. This can refer to the corresponding pocket 30 covering most or all of a section of the base surface 28 that is arranged radially outward from the radially outermost surface of each of the teeth 45 when it is completely enclosed in the corresponding recess 26. A boundary of each of the pockets 30 can extend along the inner circumferential surface 24 along most or all of the corresponding recess 26 and can further extend along the inner circumferential surface 24 to extend along at least a section of each of the teeth 25, surrounding the corresponding recess 26 on both circumferential sides.The boundary of each of the pockets 30 extending along such features may include extending directly along the intersection of the base surface 28 with the inner circumferential surface 24, or it may include recessing inward from the inner circumferential surface 24 along the base surface 28 with an offset, while extending along the same general shape as the inner circumferential surface 24. A connecting section of the boundary of each of the pockets 30 may extend away from the extension along the inner circumferential surface 24 to connect the opposite ends of the boundary, which extend along the inner circumferential surface 24 across the base surface 28, between adjacent teeth 25.

[0032] As shown here, each pocket 30 can comprise a shape having a leading section 30a and a trailing section 30b, wherein the leading section 30a is a section of each pocket 30 that leads during the circumferential rotation of the outer gerotor 20, while conversely, the trailing section 30b is a section of each pocket 30 that follows the associated leading section 30a during the circumferential rotation of the outer gerotor 20. Each pocket 30 can be subdivided into the leading section and the trailing section 30a, 30b by a radially extending axis passing through a center point of the corresponding recesses 26, which includes, as shown in the perspective from Fig. 11 shows that the leading section 30a is clockwise from the dividing axis and the rear section 30b is counterclockwise from the dividing axis, with respect to one of the pockets 30 shown in the illustration of the outer gerotor 20 above. Fig. Figure 11 further shows that the connecting section of the boundary of each of the pockets 30 can be inclined such that, along its circumference, the connecting section extends increasingly radially inward from a leading end to a trailing end of the corresponding pockets 30 with respect to a central axis of the outer gerotor 20. This inclination of the connecting section can include the connecting section intersecting the inner circumferential surface along the leading section 30a at a position along the corresponding tooth 25 that is displaced both from a vertex of the corresponding tooth 25 and from the recess 26 associated with the corresponding pocket 30, and the connecting section intersecting the inner circumferential surface along the leading section 30b at a position of the vertex of the trailing tooth 25.

[0033] The connecting section is also shown to be essentially L-shaped, with an offset segment extending radially inwards from the vertex of the rear tooth 25 and a transverse segment extending from the offset segment to the position along the leading tooth 25 that is offset from the vertex of the same.This radial inward recess of the transverse segment, extending from the apex of the rear tooth 25 through the introduction of the offset segment, may be included to ensure that a radial dimension of the pocket 30 at its rear end, corresponding to the width of a circumferential flow path along the pocket 30 from one cavity 55 to another, while each tooth 45 of the outer gerotor 40 first exposes the leading section 30b of the pocket 30, is large enough to allow rapid flow of the pumped fluid between the cavities 55 when the pocket 30 is initially brought into direct fluid communication with both adjacent cavities 55. The pocket 30 shown furthest clockwise is in . Fig. Figure 11 shows where the rear section 30b is exposed first and where the radial extension of the offset segment results in the pocket 30 having an increased orifice width and therefore an increased flow area through it, compared with the exposure of an expanding cross-section such as that which a pointed or triangular shape may provide initially.

[0034] As in Fig. 11 and Fig. As can be seen in Figure 12, each of the pockets 30 is shaped to extend over an area of ​​the base surface 28 in which at least one position of each of the teeth 45 of the inner gerotor 40 relative to each of the recesses 26 of the outer gerotor 20 includes such that the pumped fluid can be conveyed between one of the cavities 55, which is currently superimposed on the leading section 30a of the corresponding pockets 30 and is fluidically directly coupled to it, and another, adjacent cavity 55, which is currently superimposed on the rear section 30b of the corresponding pockets 30 and is fluidically directly coupled to it.It is also evident that at at least some positions of each of the teeth 45 of the inner gerotor 40 relative to each of the recesses 26 of the outer gerotor 20, a corresponding pocket 30 is fluidically coupled to only one of the cavities 55 at a given moment, for example, when a corresponding tooth 45 first encounters a corresponding pocket 30 at its leading or trailing end, or completes its movement beyond it. An example of this is shown with reference to the uppermost pocket 30. Fig. Figure 11 shows where one of the teeth 45 has just begun to pass over the rear section 30b of the pocket 30, so that no fluid communication can yet be established past the second axial end surface 42 of the inner gerotor 40.

[0035] As a review of the Fig. 11 and Fig. As can be seen in Figure 12, each of the cavities 55 is always in direct fluid communication with at least one of the pockets 30, regardless of the rotational position of the outer gerotor 20 relative to the inner gerotor 40, and at other times in direct fluid communication with two of the pockets 30 with respect to some rotational positions of the outer gerotor 20 relative to the inner gerotor 40. In fact, the disclosed configuration of the pockets 30, under limited circumstances, includes the pumped fluid being capable of fluid communication via a first pocket 30 from a first cavity 55 to a second cavity 55 and then via a second pocket 30 from the second cavity 55 to a third cavity 55, as shown, for example, with respect to the three pockets 30 arranged in the right half of the outer gerotor 20, as in Figure 12. Fig. Figure 11 shows that the disclosed pockets 30 are accordingly capable of pressure equalization across up to three of the cavities 55 when such limited circumstances occur.

[0036] The inclusion of the pockets 30 in the outer gerotor 20 reduces the maximum pressure occurring within each of the cavities 55 by creating an extra volume that can be occupied by the fluid, while also providing an additional flow path through which the fluid can flow as it progresses to another of the cavities 55, which has a lower pressure than that which is currently present in the cavity 55 from which the fluid escapes via the intermediate and connecting pocket 30.Each of the pockets 30 can accordingly support the reduction of the described internal pressure at times when adjacent cavities 55 are positioned such that they are fluidically coupled to each other via a corresponding pocket 30 extending between them, and at times when the corresponding pocket 30 is positioned relative to the inner gerotor 40 such that the corresponding pocket 30 relies primarily on the expanded flow volume provided by the inclusion of the corresponding pocket 30 within the outer gerotor 20 when reducing the internal pressure, in relation to a circumstance in which the outer gerotor 20 does not have such pockets 30.The cavity 55, from which the fluid escapes via the corresponding pocket 30, is therefore not subject to an undesirably high internal pressure that is associated with a separation of the outer gerotor 20 from the inner surface 12a of the connecting wall 12 and a corresponding escape of the fluid from the outer gerotor 20, during each compression of the pumped fluid by one of the teeth 45 relative to one of the recesses 26 via a corresponding cavity 55 formed in between.

[0037] According to a second pressure relief feature of the present invention, each of the recesses 26 formed between adjacent teeth 25 of the outer gerotor 20 can further comprise the formation of a pocket 35 therein. Each pocket 35 can be formed by a section of the inner circumferential surface 24 of the outer gerotor 20 that is radially outwardly recessed along a corresponding recess 26 relative to an adjacent and axially extending surface of the same recess 26 in order to extend the flow volume of a corresponding cavity 55 radially outward. Each pocket 35 thus forms a section of the circumferential surface 24 that does not come into contact with any of the teeth 45 of the inner gerotor 40, since the pockets 35 are in all circumstances arranged radially outward from the teeth 45.That is, each of the recesses 26 comprises a radially outwardly arranged first section, formed by one of the pockets 35, and a radially inwardly arranged second section without the formation of one of the pockets 35, wherein the first section with one of the pockets 35 has a larger inner (root) radius from the axis of rotation of the outer gerotor 20 than the second section without one of the pockets 35, which is thus closer to the teeth 45 of the inner gerotor 40 with respect to the radial direction of the outer gerotor 20 than the surface that defines the adjacent pocket 35.Each of the pockets 35 extends axially from the edge 23 of the outer gerotor 20 towards the base surface 28, before terminating therein and transitioning radially inward into the configuration of the remainder of the corresponding recess 26, such that each of the recesses 26 comprises a relatively enlarged radial dimension toward the edge 23 and a relatively reduced radial dimension toward the base surface 28. In the present embodiment, each of the pockets 35 transitions into the second section of the corresponding recess 26 without forming one of the pockets 35 approximately halfway between the base surface 28 and the edge 23 with respect to the axial direction of the outer gerotor 20. However, the pockets 35 can extend along different axial lengths of the inner circumferential surface 24 as desired, without departing from the scope of the present invention.

[0038] As in Fig. Figure 7, which is an enlarged view of the connecting wall 12 and shows its inner surface 12a, shows that the formation of the pockets 35 in the outer gerotor 20 can be coupled with the inclusion of a radially outwardly extending section 17a of a periphery of the outlet opening 17, where the outlet opening 17 intersects the inner surface 12a of the connecting wall 12. The periphery of the outlet opening 17 comprises a radially outer side extending counterclockwise from an upper end of the outlet opening 17, as shown in Figure 7. Fig. Figure 7 shows a first section with a constant radius of curvature relative to the central axis of the outer gerotor 20, which then transitions radially outward with an offset, the radially outwardly extended section 17a being formed along a second section which, in the illustrated embodiment, also continues counterclockwise to encompass its own constant radius of curvature, which is larger than that of the remaining boundary of the outlet opening 17, relative to the central axis of the outer gerotor 20. The radially outwardly extended section 17a is recessed radially outward relative to the axis of rotation of the outer gerotor 20 beyond a radially outermost surface of each of the second sections of the recesses 26, which does not have any of the pockets 35.The radially outwardly extended section 17a extends radially outward to such an extent that the extended section 17a overlaps with an axial end of each of the pockets 35 arranged along the edge 23 of the outer gerotor 20, allowing fluid to flow directly from the interior of one of the pockets 35 into the outlet opening 17 in the axial direction as soon as the corresponding pocket 35 reaches the radially outwardly extended section 17a of the edge of the outlet opening 17 during a circumferential movement of the same, such as occurs during the rotation of the gerotors 20, 40.

[0039] This effect is most easily seen from a comparison of Fig. 13 and Fig. 14 understandable, which are cross-sectional views taken directly on the inner surface 12a of the connecting wall 12, in order to show the shape of the boundary of the inlet opening 16 and the outlet opening 17 on the inner surface 12a and relative to the formation and subsequent compression of the cavities 55 formed between the inner and outer gerotors 20, 40. In Fig. 13 is one of the pockets 35 (shown in outline with dashed lines) axially aligned with a section of the inner surface 12a of the connecting wall 12 to block a direct axial flow from the pocket 35 into the outlet opening 17, while in Fig. 14 the same pocket 35 (clockwise) has rotated to a position where the fluid contained in the pocket 35 can flow directly axially out of the pocket 35 and over the boundary of the outlet opening 17, due to the radial outward extension of its periphery caused by the formation of the extended section 17a to the radial position of the pocket 35.

[0040] Each of the pockets 35 accordingly provides both an additional flow volume for receiving additional fluid and a flow path to allow a portion of the fluid compressed along the side of the outlet opening 17 of the gerotor pump 10 to escape from the corresponding cavity 55 and exit to the outlet opening 17 when the maximum degree of fluid compression occurs during the maximum engagement of one of the teeth 45 in one of the recesses 26. The presence of the pockets 35 thus reduces the pressure occurring within the outer gerotor 20 by allowing a greater portion of the fluid to flow out of each cavity 55 during compression, while also providing an increased volume to generally reduce the pressure of the fluid as it passes through the outer gerotor 20.

[0041] Fig.Figure 7 also shows the periphery of the outlet opening 17 with a radially inwardly widened section 17b, which is radially inwardly deepened further than the remainder of the inner periphery of the outlet opening 17, extending along and around the sleeve 13 which accommodates the shaft 60, the remainder of the inner periphery otherwise comprising a constant radius of curvature larger than that of the radially inwardly widened section 17b. The radially inwardly widened section 17b is located at or adjacent to the termination of the compression of each of the cavities 55 for receiving the pumped fluid when it is under relatively high pressure.This radial inward recess results in an enlargement of the flow area through the outlet opening 17, where the pressure of the fluid is maximized, allowing the fluid to exit the outer gerotor 20 more quickly, so that no excessive pressure builds up at the end of each compression cycle and thus contributes to the formation of excessive internal pressures in the gerotor pump 10.

[0042] Simulations relating to the gerotor pump 10 of the present invention with the configuration of the pockets 30, 35 show that the gerotor pump 10 is subject to significantly reduced internal pressures under typical operating conditions compared to the same gerotor pump without such features. Therefore, the gerotor pump 10 of the present invention advantageously helps prevent the outer gerotor 20 from separating from the inner surface 12a of the connecting wall 12, which would otherwise cause the pumped fluid to flow undesirably beyond the edge 23 of the outer gerotor 20. The disclosed gerotor pump 10 also avoids cases of excessive tilting of the outer gerotor 20 relative to the guide provided by features such as the sleeve 13, thereby preventing wear resulting from undesired frictional engagement between such surfaces during rotation of the outer gerotor 20.

[0043] The gerotor pump 10 is consistently shown in the present figures with both the pockets 30 and the pockets 35 in combination. However, it is evident that the gerotor pump 10 can be configured such that only one of the pockets 30 or 35 is used without departing from the scope of the present invention, since the pressure-reducing features provided by one of the pockets 30 or 35 are not dependent on the presence of the other pocket 30 or 35 described herein. That is to say, the advantages of the pockets 30 are also noticeable in the absence of the pockets 35, and likewise, the advantages of using the pockets 35 (together with corresponding modifications to the structure of the outlet opening 17) are also noticeable in the absence of the pockets 30.

[0044] From the foregoing description, the person skilled in the art can easily deduce the essential features of this invention and, without departing from its spirit and scope, can make various modifications and alterations to the invention to adapt it to different uses and conditions.

Claims

[1] Gerotor pump which has the following features: an outer gerotor (20) with an opening defined by an inner surface thereof; an inner gerotor (40) which is accommodated within the opening of the outer gerotor (20), wherein a plurality of cavities (55) are formed between the inner gerotor and the outer gerotor; and a plurality of first pockets, each of the first pockets being formed as a depression in the inner surface of the outer gerotor, each of the first pockets forming a first pressure relief feature to prevent overpressure within each of the cavities (55) formed between the outer gerotor (20) and the inner gerotor (40). [2] Gerotor pump according to claim 1, wherein the inner surface of the outer gerotor (20) comprises a base surface (28) and an inner circumferential surface (24) extending axially from a periphery of the base surface, wherein the plurality of first pockets is formed in a region formed by the base surface and the inner circumferential surface. [3] Gerotor pump according to claim 2, wherein each of the first pockets in the base surface (28) is formed as an axially recessed surface of the same, wherein the inner gerotor (40) comprises an axial end surface configured to engage with the base surface of the outer gerotor (20), wherein the axially recessed surface defining each of the corresponding first pockets is axially spaced from the axial end surface of the inner gerotor. [4] Gerotor pump according to claim 3, wherein a flow path is formed where the axial end surface of the inner gerotor (40) is directly directed towards the axially recessed surface which forms a corresponding pocket. [5] Gerotor pump according to claim 4, wherein the flow path is in direct fluid communication with at least one of the cavities (55) formed between the inner gerotor (40) and the outer gerotor (20). [6] Gerotor pump according to claim 5, wherein the flow path establishes direct fluid communication between two of the cavities (55) formed between the inner gerotor (40) and the outer gerotor (20). [7] Gerotor pump according to any one of claims 2 to 6, wherein the inner circumferential surface (24) of the outer gerotor (20) is corrugated to comprise alternating outer teeth and outer recesses around the circumference, each of the plurality of first pockets being associated with a corresponding outer recess. [8] Gerotor pump according to claim 7, wherein each of the first pockets in the base surface (28) is formed as an axially recessed surface of the same, and wherein each of the first pockets covers an entirety of the base surface within the corresponding of the outer recesses. [9] Gerotor pump according to claim 7, wherein each of the first pockets in the base surface (28) is formed as an axially recessed surface of the same, wherein a first section of a boundary of each of the first pockets extends along the corresponding of the outer recesses (26). [10] Gerotor pump according to claim 9, wherein a second section of the boundary of each of the first pockets extends along a first of the outer teeth which are arranged adjacent to the corresponding of the outer recesses (26), and a third section of the boundary of each of the first pockets extends along a second of the outer teeth which are arranged adjacent to the corresponding of the outer recesses (26). [11] Gerotor pump according to claim 10, wherein the second section of the boundary extends away from the corresponding of the outer recesses to a vertex of the first of the outer teeth and the third section of the boundary extends away from the corresponding of the outer recesses to a position spaced apart from the vertex of the second of the outer teeth. [12] Gerotor pump according to claim 10, wherein a fourth section of the boundary of each of the first pockets connects the second section of the boundary with the third section of the boundary, wherein a radial distance of the fourth section of the boundary from an axis of rotation of the outer gerotor (20) varies along the course of the fourth section of the boundary between the second section of the boundary and the third section of the boundary. [13] Gerotor pump according to claim 12, wherein the radial distance of the fourth section of the boundary from the axis of rotation of the outer gerotor (20) increases in the course of the fourth section of the boundary from the second section of the boundary to the third section of the boundary, and wherein the rotation of the outer gerotor about the axis of rotation of the same comprises such that the second of the teeth leads the first of the teeth. [14] Gerotor pump according to claim 7, wherein each of the first pockets in the base surface (28) is formed as an axially recessed surface of the same, wherein the inner gerotor (40) comprises an outer circumferential surface (43) which is corrugated to include alternating inner teeth and inner recesses (46) around the circumference, and wherein at least one position of each of the inner teeth relative to each of the outer recesses comprises that one of the first pockets forms a flow path which establishes fluid communication between two of the cavities (55) formed between the outer gerotor (20) and the inner gerotor. [15] Gerotor pump according to claim 7, wherein each of the first pockets in the inner circumferential surface (24) of the outer gerotor (20) is formed as a radially outwardly recessed surface arranged along the corresponding recesses. [16] Gerotor pump according to claim 15, wherein the inner circumferential surface (24) of the outer gerotor (20) terminates at an edge (23) of the outer gerotor (20), and wherein each of the first pockets extends axially to the edge. [17] Gerotor pump according to claim 16, further comprising a housing with a connecting wall through which an outlet opening is formed, wherein the outlet opening intersects an inner surface of the connecting wall which faces and engages with the edge (23) of the outer gerotor (20), wherein a periphery of the outlet opening on the inner surface of the connecting wall comprises a first section and a second section radially offset from the first section, wherein each of the first pockets is arranged radially outward from the first section of the periphery when arranged along the same, in order to cause the inner surface of the connecting wall to cover each of the first pockets, and wherein each of the first pockets is arranged radially inward from the second section of the periphery when arranged along the same, in order to cause each of the first pockets to be exposed toward the outlet opening. [18] Gerotor pump according to claim 17, wherein the first section of the periphery, measured relative to an axis of rotation of the outer gerotor (20), comprises a constant first radius of curvature and the second section of the periphery, measured relative to an axis of rotation of the outer gerotor (20), comprises a constant second radius of curvature, wherein the second radius of curvature is larger than the first radius of curvature. [19] Gerotor pump according to claim 2, wherein each of the first pockets in the inner circumferential surface (24) of the outer gerotor (20) is formed as a radially outwardly recessed surface of the same. [20] Gerotor pump according to claim 2, further comprising a plurality of second pockets, each of the second pockets being formed as a depression in the inner surface of the outer gerotor (20), each of the second pockets forming a second pressure relief feature to prevent overpressure within each of the cavities (55) formed between the outer gerotor and the inner gerotor (40), the plurality of first pockets being formed in the base surface (28) and the plurality of second pockets being formed in the inner circumferential surface (24).

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