CN215908052U

CN215908052U - Positive displacement gear machine

Info

Publication number: CN215908052U
Application number: CN202121723184.6U
Authority: CN
Inventors: 曼纽尔·里戈西
Original assignee: Casappa SpA
Current assignee: Casappa SpA
Priority date: 2020-07-28
Filing date: 2021-07-27
Publication date: 2022-02-25
Anticipated expiration: 2031-07-27
Also published as: ES1279075Y; DE202021103986U1; IT202000018235A1; FR3113100B3; ES1279075U; KR20220000328U; FR3113100A3

Abstract

A positive displacement gear machine interacting with an operating fluid and comprising: a first toothed wheel and a second toothed wheel, which mesh with each other and interact with an operating fluid; a housing defining a housing seat for the first and second toothed wheels and comprising at least one inlet for the inflow of operating fluid into the seat and an outlet for the outflow of operating fluid from the seat. The first toothed wheel comprises at least a first set of teeth, each of which in turn comprises: two side surfaces; a frustoconical crest connecting the two sides; a groove located along the tooth crest and defining a reservoir of operating fluid. The internal volume of the recess is less than 3% of the volume of the compartment comprised between the first toothed wheel and the housing and interposed between two consecutive teeth; the groove connects first and second opposite faces of the first toothed wheel to each other. The gear machine minimizes the risk of adhesion between the material of the teeth and the housing, optimizes the quietness of operation, and prevents the occurrence of damages or dents which are detrimental to the optimal operation.

Description

Positive displacement gear machine

Technical Field

The present application relates to positive displacement machines that interact with an operating fluid. It is a pump or a motor. It is therefore capable of transferring an operating fluid between two environments where there is a pressure differential between them. In the case of a pump, the fluid is transferred from the lower pressure region to the higher pressure region. In the case of a motor, fluid is transferred from the higher pressure region to the lower pressure region.

Background

Gear pumps are known in which two toothed wheels intermesh within a seat and enable the transfer of operating fluid from an inlet to an outlet. Along this path, an operating fluid (typically oil) may be found between the pairs of teeth of such a toothed wheel. The teeth overlap (lap) at their own tooth tips a housing which defines a seat housing the toothed wheel.

Gear pumps of the type described in DE2200547, NL1016283, US2601003, WO2004/109110 are also known.

In this context, if the tooth crests have a sufficiently large width, there may be a risk of undesired adhesion between the material defining the tooth crests and the material of the housing. This can damage the moving parts, irreversibly compromising the efficiency of the positive displacement machine. It can also generate noise.

SUMMERY OF THE UTILITY MODEL

In this context, the technical task underlying the present application is to propose a volumetric machine interacting with an operating fluid that is able to minimize the above-mentioned drawbacks.

The technical task and the specific objects are fully achieved by a positive-displacement machine comprising the technical features disclosed hereinafter.

A positive displacement gear machine for interacting with an operating fluid, the positive displacement gear machine being a pump and/or a motor and comprising: a first toothed wheel and a second toothed wheel, the first and second toothed wheels being intermeshed and interacting with the operating fluid; a housing defining a containment seat for the first and second toothed wheels and comprising at least one inlet for the operating fluid to flow into the containment seat and an outlet for the operating fluid to flow out of the containment seat; the first toothed wheel includes a first opposing face and a second opposing face; the first toothed wheel extending axially between the first and second opposing faces; the first toothed wheel comprises at least a first set of teeth, each tooth of the first set of teeth in turn comprising: two side surfaces; a frustoconical crest connecting said two sides; a recess disposed along the frustoconical tooth crest and defining a reservoir for the operating fluid, wherein the recess defines an internal volume that is less than 3% of a volume of a compartment included between the first toothed wheel and the housing and interposed between two consecutive teeth of the first set of teeth; the groove connects the first opposing face and the second opposing face to each other.

Further, the recess has an internal volume of less than 1.5% of the volume of the compartment comprised between the first toothed wheel and the housing and interposed between two consecutive teeth of the first set of teeth.

Further, the teeth of the first set of teeth have a helical extension.

Further, the groove has a main longitudinal extension; the groove defines a cross-section through the main longitudinal extension along the main longitudinal extension, the cross-section extending with a height and a width.

Further, the cross section remains constant along the entire main longitudinal extension.

Further, the ratio between the height and the width is comprised between 0.5 and 2 over the entire main longitudinal extension of the groove.

Further, said width is greater than said height over the entire main longitudinal extension of said groove.

Further, the groove includes: a side wall projecting toward an interior of the first toothed wheel; a bottom surface extending transverse to the side wall.

Further, the groove affects between 25% and 50% of a surface of the tooth top that faces the housing.

Further, the groove does not lead into one or both of the compartments interposed between two consecutive teeth.

The positive displacement gear machine of the present application minimizes the risk of adhesion between the material of the teeth and the housing, optimizes the operation silence, and prevents the occurrence of damages or dents that are not conducive to optimal operation.

Drawings

Further characteristics and advantages of the present application will become more apparent from the description of a preferred but not exclusive embodiment of a positive-displacement machine, with reference to the accompanying drawings, which are schematically illustrated in the following figures:

figure 1 shows a cross-sectional view of a positive displacement machine according to the present application;

figure 2 shows a perspective view of the components of the volumetric machine of figure 1;

FIGS. 3 and 4 show cross-sectional views of portions of the component of FIG. 2;

fig. 5, 6, 7 and 8 show cross-sectional views of alternative solutions to the solution of fig. 4.

Detailed Description

In the figures, reference numeral 1 denotes a positive-displacement machine interacting with an operating fluid. It is a fluid dynamic positive displacement machine. The positive displacement machine is a pump or a motor. It may also have unidirectional or reversible operation and operate as both a pump and a motor. Thus, it may (alternatively) operate as both a pump and a motor.

It is therefore a gear motor or gear pump.

Typically, the operating fluid is oil. However, it may be another fluid that is not compressible or is not too compressible.

Suitably, the volumetric machine 1 comprises a first toothed wheel 21 and a second toothed wheel 22, which are meshed with each other and interact with said operating fluid. Preferably, the first toothed wheel and the second toothed wheel rotate about axes of rotation that are parallel to each other. In a preferred solution, the first toothed wheel 21 and the second toothed wheel 22 are both external to each other. In this case, the teeth are arranged on the outer peripheral surface (typically on the outer periphery) of each wheel 21 and 22. Suitably, the first wheel 21 and the second wheel 22 are toothed wheels of the "cylindrical" type (and therefore not conical, for example). In an alternative, non-preferred solution, one of the two wheels may be at least partially surrounded by the other. Thus, in this case, one of the two toothed wheels 21 and 22 can be engaged with the other and located inside it. Thus, in this case, one of the two toothed wheels has teeth facing outwards and the other has teeth facing inwards.

The volumetric machine 1 comprises a casing 300 defining a seat 3 for housing a first wheel 21 and a second wheel 22. Such a housing 300 typically comprises a plurality of parts assembled to each other, such as a main body and one or two closed covers or two half shells, etc. The housing 300 is static.

The housing 300 comprises at least one inlet 33 for the inflow of operating fluid into said base 3 and an outlet 34 for the outflow of operating fluid from said base 3.

In a preferred solution, said inlet 33 opens into a space 200, which is at least partially interposed between the first toothed wheel 21 and the second toothed wheel 22. The first and second toothed wheels 21, 22 rotate in opposite directions, collecting at least a portion of the fluid from the space 200 and transporting the fluid toward the outlet 34. To this end, the fluid is gradually introduced into the compartments interposed between the successive teeth of each toothed wheel 21 and 22. The first toothed wheel 21 and the second toothed wheel 22 transport the fluid along two alternative paths which recombine in the vicinity of the outlet 34.

The first wheel 21 comprises at least a first set of teeth 4. In a preferred solution, the first set of teeth 4 comprises or coincides with all the teeth of the first toothed wheel 21 (cogide). In an alternative solution, it may comprise only a part of the teeth. For example, but not necessarily, the teeth of the first toothed wheel 21 are comprised between 8 and 15, preferably between 10 and 13, advantageously 11 or 12. The teeth of the first set of teeth 4 are advantageously provided on the outer peripheral surface of the first toothed wheel 21.

Each tooth of the first set 4 of teeth in turn comprises:

two

sides

41, 42;

a crest 43, connecting the two lateral faces 41, 42. Such tooth crests 43 are advantageously frustoconical. Suitably, the tooth crests define a discontinuity (e.g. by corresponding corners) with respect to the profile of the side faces 41, 42. The tooth top 34 may be shaped as a portion of a side surface like a cylinder (typically having a large radius of curvature). Suitably, the tooth top 43 is substantially flat. It is shaped like a strip.

Suitably, the two lateral faces 41, 42 connect the crest 43 and the base 23 from which the teeth of the first set 4 project in cantilever fashion. The teeth of the first set 4 of teeth project in cantilever fashion from the base 23 to a more radially outer position. Such a base 23 is therefore the bottom of a compartment interposed between two consecutive teeth. Suitably, the teeth of the first set 4 of teeth project outwards in a radial or substantially radial direction.

Suitably, the two lateral faces 41, 42 extend according to an involute profile (extending for at least a portion of its profile or for the entire length of its profile). The portion of one of the two

flanks

41, 42 extending as the involute of a circle advantageously affects the height of the teeth of the first group of teeth 4 greater than 1/3, preferably at least 1/2. The height of the tooth means the difference between the tooth tip radius and the tooth root radius.

In line with common practice in the technical field, the involute profile also means that the profile has a correction of a few tenths of a millimeter with respect to the theoretical involute (in the case in question, the displacement is less than 5% of the normal tooth model). It is emphasized that in the technical field, the normal model of a tooth is defined as: d/Z · cos β, wherein:

d: an original radius;

z: the number of teeth;

beta: the helix angle at the original radius (equal to 0 ° if straight teeth).

Suitably, each tooth of the first set 4 comprises a recess 44 arranged along said frusto-conical crest 43. Preferably, such crests 43 define the area where the grooves 44 are provided. Such a region is shaped like a portion of the lateral surface of a cylinder (suitably with a large radius of curvature), for example. Suitably, the tooth top 43 is generally flat (e.g., it is planar or has a slight convexity defined by a large radius of curvature). The recess 44 suitably defines a concave surface projecting into one tooth of the first set 4 of teeth.

In a preferred solution, the groove 44 extends continuously in each tooth of the first set 4 of teeth. Suitably, there is only one recess 44 in the crest 43 of each tooth of the first set 4.

The groove 44 enables to define a small reservoir of operating fluid. This operating fluid exerts a lubricating effect. This therefore prevents adhesion between the material defining the crests of the teeth of the first set of teeth 4 and the material of the housing 300.

The internal volume of the groove 44 (to the groove) is less than 3% (preferably, 1.5%, even more preferably, 1%) of the volume of the compartment 30 comprised between the first wheel 21 and the casing 300 and interposed between two consecutive teeth of said first set of teeth 4. In fact, the volume containing the groove 44 makes it possible to reduce the capacity of the contained volumetric machine 1. In fact, the capacity of this type of machine is defined as the difference between the volumes that can be occupied by the fluid inside one compartment between two teeth when this compartment is empty and the volume occupied by the fluid inside this same compartment in a configuration in which the teeth of the other wheel are intended to project into this compartment, reduced by x times the maximum possible space (x means doubling the teeth of the toothed wheel). In other words, the capacity is defined on the basis of the maximum volume change, wherein the compartment between two teeth undergoes one full rotation about the axis. Thus, if the teeth projecting into such a compartment have a large groove 44, the decrement will be larger. The empty compartment is defined in a configuration in which no tooth of the other wheel protrudes into it.

In a preferred solution, the teeth of said first set of teeth 4 have a helical extension. In fact, taking a sufficiently large tooth tip (in the transverse direction with respect to the axial direction) enables a greater degree of freedom in the dimensions of the teeth, and this is particularly advantageous in the case of toothed wheels comprising a plurality of teeth. However, in an alternative solution, the teeth of the first set of teeth 4 may be straight teeth (aligned with a plane containing the axis of rotation).

Suitably, the meshing between the teeth of the first set 4 of teeth may be a single-sided contact or a double-sided contact (in the latter case, the meshing teeth are in contact in two different regions on opposite sides).

The groove 44 has a major longitudinal extension. The groove 44 may extend longitudinally along a straight line or line (which may also not be straight, but has at least one curved portion). Along said longitudinal extension, the groove 44 defines a section 31 with respect to the longitudinal extension. The cross-section extends with a height 311 and a width 312.

Suitably, the ratio between said height 311 and said width 312 is comprised between 0.5 and 2 over the entire longitudinal extension of the groove 44.

Preferably, the ratio between said height 311 and said width 312 is comprised between 0.8 and 1.5 over the entire longitudinal extension of the groove 44.

The width 312 is greater than the height 311 over the entire longitudinal extension of the groove 44.

Height 311 defines the depth of groove 44 relative to the surface from which groove 44 extends inward of first wheel 21. The height 311 extends in a substantially radial direction. Width 312 defines the distance between the two sidewalls of groove 44. Such walls are usually connected by a bottom. Suitably, the bottom is flat or has a non-empty width (transverse to the longitudinal extension). The side wall extends along the longitudinal extension. The sidewalls may remain parallel to each other or move toward each other when protruding toward the bottom. The groove 44 is open on the opposite side to the bottom towards the outside of its entire longitudinal extension. Suitably, any section of the groove 44 is equidistant with respect to the two

sides

41 and 42 of the tooth.

Advantageously, the groove 44 affects between 25% and 75% of the tooth crests 43, preferably between 25% and 50% of the tooth crests 43.

In an exemplary but non-limiting solution, any section is at least 1 mm from the two

sides

41, 42 of the tooth. Suitably, the groove 44 does not lead to one or both components being inserted in the compartment between two consecutive teeth.

Advantageously, the width and/or height of the section 31 remains constant for the entire longitudinal extension. Suitably, in a preferred solution, the section 31 remains constant for the whole longitudinal extension. This facilitates the creation of the groove 44. Advantageously, the section 31 remains a constant section within at least one tooth of the first set of teeth. Preferably, the cross-section 31 is the same size in the grooves of all the teeth of the first set 4 of teeth. Thus, the grooves belong to different teeth, but are identical to each other as part of the first set of teeth 4.

The first toothed wheel 21 comprises a first opposite face 211 and a second opposite face 212.

The first wheel 21 extends between a first opposite face 211 and a second opposite face 212. The groove 44 connects the first opposing face 211 and the second opposing face 212 to each other. The groove 44 is thus advantageously open at both opposite ends. The groove 44 is guided to the outside at the first opposing face 211 and the second opposing face 212 (wherein the end portions of the groove 44 are provided in the first opposing face and the second opposing face). Suitably, the recess 44 is a through slot. In the preferred solution, therefore, the groove 44 passes through the first wheel 21 from one side to the other. The teeth extend along the thickness (suitably meaning the axial length) of the first toothed wheel 21 to connect the first opposite face 211 and the second opposite face 212. The groove 44 for connecting the first 211 and second 212 opposite faces follows the continuation of the extension line of the teeth assumed to be along the thickness of the first toothed wheel 21. In particular, if the teeth are straight, the grooves 44 will be rectilinear, and if the teeth are helical, the grooves will be curvilinear (in particular helical). The first and second opposite faces respectively face two different lateral balancing plates or covers.

Suitably, the second toothed wheel 22 also comprises a first set of teeth; each tooth of the first set of teeth in turn comprises:

-two sides;

-a truncated-cone-shaped tooth crest connecting the two side faces;

-a recess located along the crest of the truncated cone.

Suitably, one or more of the characteristics described for the teeth of the first set 4 of teeth of the first wheel 21 may be used to repeat the description of the teeth of the first set of teeth of the second wheel 22. In particular, the characteristics described for the grooves 44 of the teeth of the first wheel 21 can be used to repeat the description of the grooves of the teeth of the second wheel 22.

The present application achieves important advantages.

In fact, it minimizes the risk of adhesion between the material of the teeth of the wheel and the casing, optimizes the quietness of operation and prevents the occurrence of damages or dents that are detrimental to optimal operation.

It is contemplated that the present application is susceptible to many modifications and variations, all of which fall within the scope of the conceptual features of the application. Also all the details may be replaced with other technically equivalent elements. In practice, all the materials used, as well as all the dimensions, may be of any form according to requirements.

Claims

1. A positive displacement gear machine for interacting with an operating fluid, the positive displacement gear machine being a pump and/or a motor and comprising:

a first toothed wheel (21) and a second toothed wheel (22) which mesh with each other and interact with the operating fluid;

a housing (300) defining a containment seat (3) for said first toothed wheel (21) and said second toothed wheel (22) and comprising at least one inlet (33) for the inflow of said operating fluid into said containment seat (3) and an outlet (34) for the outflow of said operating fluid from said containment seat (3); the first toothed wheel (21) comprising a first opposite face (211) and a second opposite face (212); the first toothed wheel (21) extending axially between the first opposite face (211) and the second opposite face (212);

said first toothed wheel (21) comprising at least a first set of teeth (4), each tooth of said first set of teeth (4) in turn comprising:

two lateral faces (41, 42);

a truncated-cone-shaped tooth crest (43) connecting said two lateral surfaces (41, 42);

a groove (44) provided along the tooth crest (43) of the truncated cone shape and defining a reservoir for the operating fluid,

characterized in that said groove (44) defines an internal volume which is less than 3% of the volume of a compartment (30) comprised between said first toothed wheel (21) and said housing (300) and interposed between two consecutive teeth of said first set of teeth (4); the groove (44) connects the first opposing face (211) and the second opposing face (212) to each other.

2. A positive-displacement gear machine according to claim 1, characterized in that said groove (44) has an internal volume of less than 1.5% of the volume of the compartment (30) comprised between the first toothed wheel (21) and the casing (300) and interposed between two consecutive teeth of the first set of teeth (4).

3. A positive-displacement gear machine according to claim 1 or 2, characterized in that the teeth of the first set of teeth (4) have a helical extension.

4. A positive-displacement gear machine according to claim 1 or 2, characterized in that the groove (44) has a main longitudinal extension; the groove (44) defines a section (31) through the main longitudinal extension along the latter, the section (31) extending with a height (311) and a width (312).

5. A positive-displacement gear machine according to claim 4, characterized in that said section (31) is constant along the entire main longitudinal extension.

6. Positive-displacement gear machine according to claim 4, characterized in that the ratio between said height (311) and said width (312) is comprised between 0.5 and 2, over the entire main longitudinal extension of said groove (44).

7. A positive-displacement gear machine according to claim 4, characterized in that said width (312) is greater than said height (311) over the entire main longitudinal extension of said groove (44).

8. A positive-displacement gear machine according to claim 1 or 2, wherein the groove (44) comprises:

a side wall projecting toward an interior of the first toothed wheel;

a bottom surface extending transverse to the side wall.

9. A positive-displacement gear machine according to claim 1 or 2, characterized in that the groove (44) affects between 25% and 50% of the surface of the tooth top (43) facing the housing (300).

10. A positive-displacement gear machine according to claim 1 or 2, characterized in that the groove (44) does not lead into one or both of the compartments interposed between two consecutive teeth.