ES2735208T3 - A positive displacement pump with a blade rotor - Google Patents

Abstract

A positive displacement pump with variable displacement comprising: - a blade rotor (2); - a stator (3) comprising a collar (30) internally from which the rotor (2) can rotate; the stator (3) and a rotational axis (20) of the rotor (2) moving relative to each other in such a way that they vary the volume of the pump (1); the collar (30) defining at least a first channel (4) to allow or contribute to an introduction of fluid between the rotor (2) and the stator (3); reducing the first channel (4) an axial thickness of the collar (30) in an area in which it is formed; characterized in that when it moves from a radially more external position (991) to a radially more internal position (992), the first channel (4) defines a ramp (99) that reduces the depth of the first channel (4), said depth being measured in parallel to the axis (20) of rotation.

Description

DESCRIPTION

A positive displacement pump with a blade rotor

The present invention relates to a positive displacement pump with a blade rotor. The pump is preferably used but not necessarily to lubricate engines.

Positive displacement pumps with blade rotors comprise a rotor provided with radial grooves in which the blades are positioned.

The pump further comprises a suction conduit, a fluid supply conduit and an internal stator from which the rotor rotates. The rotor is arranged eccentrically with respect to the stator. During use the blades are pushed against the stator.

In the technical sector, the space between two blades is usually defined as the "compartment". The compartment rotates together with the rotor. When the compartment is placed in communication with the suction duct, it increases its own volume; When the compartment is placed in communication with the supply duct, the compartment reduces its own volume, forcing the fluid out of the stator.

In a first known design version, the stator comprises an annular collar that identifies a chamber that houses the rotor. This chamber is delimited not only by the external collar but also by two opposite walls in which an inlet and an outlet of the liquid are formed.

In order to increase the flow rate of processed fluid, the collar can comprise, in the vicinity of the inlet, a channel that facilitates the introduction of the fluid. This channel, where present, reduces the axial thickness of the stator collar.

The interaction between the fluid aspirated into the stator after having passed through said channel and the short-circuited fluid already present in the stator generates turbulence, unwanted vortices, disturbances in the local pressure distribution. All of the above also causes high speed cavitation problems.

US2011 / 189043 and EP2351934 disclose known vane pumps.

In this context, the technical task on which the present invention is based is to provide a positive displacement pump with a blade rotor that allows to increase the amount of fluid that can be introduced internally into the stator while at the same time optimizing the dynamics of fluids A further objective of the present invention, strictly related to the preceding objective, is to improve the cavitation behavior of the pump and the dynamic fluid performance thereof.

A further objective of the present invention is to reduce noise levels.

The expressed technical task and specified objectives are substantially achieved by a positive displacement pump with a blade rotor comprising the technical characteristics disclosed in one or more of the appended claims. Additional features and advantages of the present invention will become more apparent from the following indicative, and therefore not limitative, description of a preferred, but not exclusive, embodiment of a positive displacement pump with a blade rotor as illustrated in the accompanying drawings, in which: Figures 1 and 2 are seen with some sectional parts of a pump according to the present invention; - figure 3 is an enlargement of figure 1;

- Figures 4-6 illustrate a component of the pump of Figure 3 from various angles;

- Figure 7 illustrates the operation of a pump according to the preceding figures;

- Figures 8-10 illustrate a component of the pump of Figures 4-6 from various angles;

- Figures 11 and 12 illustrate two sectional views of a pump according to the present invention;

- Figure 13 is a plan view of a pump component according to the present invention;

- Figure 14 or 15 illustrates the fluid path internally of a part of the pump.

In the accompanying figures, reference number 1 denotes a positive displacement pump of variable volume that interacts with a fluid (a liquid), for example lubricating oil.

It comprises a blade rotor 2. The rotor 2 can rotate about a rotation axis 20. The rotor 2 comprises a plurality of grooves 33 each housing one of said blades 32. Typically the grooves 33 extend radially.

The pump 1 further comprises a stator 3. The stator 3 comprises a collar 30 internally from which the rotor 2 can rotate. The collar 30 is also known in the technical sector as the outer ring. The collar 30 surrounds the rotor 2, in particular it surrounds the axis of rotation 20.

Stator 3 defines a chamber 34 for housing the rotor 2. Chamber 34 is advantageously cylindrical. The pump 1 comprises a first and a second plane 311, 312 (see for example Figure 11) that are transverse to the axis of rotation 20 and occlude the chamber 34, together with the collar 30.

The rotor 2 and the stator 3 are eccentric.

The stator 3 and a rotation axis 20 of the rotor 2 are movable relative to each other in such a way that they vary the volume of the pump 1. In other words the position of a cylindrical axis of the chamber 34 may vary in relation to the position of the rotation axis 20 of the rotor 2. The rotation axis 20 preferably remains fixed and the position of the stator 3 is modified. In order to modify the volume, the stator 3 can advantageously rotate around a hinge area or it can move.

Stator 3 (collar 30) defines at least a first channel 4 that contributes to an introduction of fluid between the rotor 2 and the stator 3. The first channel 4 is a decline or a notch.

The first channel 4, in an area in which it is formed, reduces an axial thickness of the collar 30 (the axial thickness of the collar is evaluated axially, ie parallel to the axis of rotation 20). The pump 1 suitably comprises a fluid supply conduit 9 that opens towards the chamber 34. The supply conduit 9 opens towards the chamber 34 at least through an aspiration opening 90 provided in the first plane 311. The first channel 4 faces and is located in said suction opening 90.

The supply conduit 9 comprises a baffle 900 that generates a first and a second rail 901, 902 for the fluid stream. The first and second lanes 901,902 diverge from each other. Along the outflow direction, the first and / or the second rail 901,902 have a reduction in the cross-section.

In this regard, observe not only figures 11-13 but also figures 14 and 15, which nevertheless illustrate the compartment 905 that the fluid can occupy during the movement thereof along the conduit 9 and not the exterior of the conduit 9 This deflector 900 is a narrowing member of the conduit 9, which functions as a distributor of the fluid along the first and second rail 901,902, facilitating the entry of the fluid into the chamber 34.

The suction opening 90 extends between a first and a second end 903, 904 (see, for example, Figure 13); the first and second ends 903, 904 determine the phase of the pump 1.

The first end 903 faces a circumferential portion of the rotor 2 that is more downstream than the circumferential portion faced by the second end 904 (in this case upstream and downstream are calculated with respect to the direction of rotation of the rotor 2) . The first rail 901 ends at the first end 903 of the suction opening 90; the second rail 902 ends at the second end 904 of the suction opening 90. The first lane 901 has a larger passage section with respect to the second lane 902 (see, for example, Figure 13). In fact, the first rail 901 reduces the misalignment of the fluid with the fluid present in the chamber 34. In other words, the first rail 901 increases a component of the fluid movement that is oriented towards the direction of rotation of the rotor 2. In particular the fluid movement component perpendicular to a radial direction (or in terms tangential to an internal circumference of chamber 34 and coaxial to axis 20 of rotation) increases.

The second rail 902 allows not to alter the phase of the pump 1 and direct the smallest possible amount of fluid to the volume.

The supply conduit 9 is profiled in such a way that it eliminates or in any case minimizes the presence of living edges. This is in order to guide the fluid more effectively, reducing dynamic fluid losses and therefore the possibility of incurring cavitation phenomena.

The first channel 4 advantageously directs the fluid in such a way that it reduces a misalignment between a first fluid flow that comes from said first channel 4 and a second fluid flow that intercepts the first flow and transits, extracted by the rotor 2, between the first channel 4 and rotor 2. The second flow is the short-circuited fluid already present in the stator 3. For example in Figure 7 the first fluid flow is denoted by the reference letter "a" and the second fluid flow It is denoted by the reference letter "b".

In other words, the first channel 4 increases the fluid component oriented in the direction of rotation of the rotor 2 (in particular the tangential component perpendicular to the radial direction).

The first channel 4 comprises a first and a second wall 41, 42 which are facing each other. Advantageously there is at least one straight segment that connects the first and second wall 41.42 without intercepting the rotor 2. The fact that the first and second walls 41.42 face each other is important since it means that the distance between the first and the second wall 41.42 is limited; this allows to guide and direct the fluid (if the distance between the first and second wall 41, 42 were excessive the first channel 4 would not succeed in effectively channeling the fluid in the desired direction).

The first channel 4 comprises a base surface 43 for connecting the first and the second wall 41, 42. In the version illustrated in Figures 4-7, the first and the second wall 41, 42 are connected without sharp edges to the surface 43 base. In the version illustrated in Figures 8-10, on the other hand, a living edge is present between the base surface 43 and the first wall 41; a live edge is also present between the base surface 43 and the second wall 42.

The collar 30 comprises an annular surface 31 that faces and surrounds the rotor 2. The minimum distance between the first and second wall 41.42 measured along the annular surface 31 is less than 1/3 of the minimum length of a line which, placed completely on the annular surface 31, surrounds the rotor 2. In particular, the minimum distance between the first and the second wall 41.42 measured along a circumference defined by the annular surface 31 is less than 1 / 3 of the circumference.

The blades 32 are advantageously radially interposed between a centering ring 5 and the annular surface 31. The centering ring 5 limits the maximum insertion of the blades 32 into the grooves 33. The centering ring 5 advantageously remains coaxial to the annular surface 31 as it is in contact with the radially innermost part of the blades 32.

As shown by way of example in Figures 1-7 the second wall 42 can be connected to the annular surface 31. The second wall 42 and the annular surface 31 are advantageously tangential in a common joint area 91 (indicated for example in Figure 3).

The version given by way of example in Figures 8-10 is the result of dynamic fluid simulations made using dedicated software.

In general, the annular surface 31 extends along a circle. The first channel 4 defines a fluid outlet mouth 44 in an area interposed between the rotor 2 and the stator 3. The mouth 44 is preferably delimited by two planes 93, 94 which between them form an angle of less than 100 ° (see for example figures 5 and 9). The intersection between the two planes 93, 94 is along a straight line that:

- is parallel to axis 20 of rotation;

- passes through a center of said circle.

The fact that the outlet mouth 44 involves a limited portion of a circumferential extension of the collar 30 allows the operating fluid to be directed to a predetermined area.

When moving from a radially outermost position 991 to a radially innermost position 992, the first channel 4 advantageously comprises a ramp 99. The ramp 99 reduces the depth of the first channel 4 (the depth is measured parallel to the axis 20 of rotation) .

The depth of the first channel 4, measured in parallel to the axis of rotation 20 is on average smaller at the outlet 44 than in the radially outermost opening 450. The specifications described above allow to guide the fluid and make it converge in the desired position.

In particular, with reference to the version given by way of example in Figures 8-10, the depth of the first channel 4 (measured in parallel to the axis 20 of rotation of the rotor 2) is zero or in any case tends to 0 in the annular surface 31. In this case, the extension of the annular surface 31 that the end of the blades 32 can increase is increased, thereby increasing the volumetric efficiency, the dynamic fluid performance and the pump performance 1. As it moves from a point radially more external to a radially more internal point, the depth of the first channel 4 is progressively reduced. In particular, in this version the base surface 43, moving from a radially more external position to a radially more internal position, progressively reduces the depth of the first channel 4. This occurs advantageously over the entire radial extension of the first channel 4. Additionally , in figure 10 line 95 indicates a change of slope.

With reference to the various versions illustrated, the axial thickness of the collar 30 increases progressively as it passes from the first to the second wall 41, 42. In particular, the axial thickness of the collar 30 on the base surface 43 increases progressively as which passes from the first to the second wall 41, 42. This also allows better fluid guidance, directing it as schematically indicated in Figure 7.

As shown in the accompanying drawings, the first channel 4 crosses the collar 30 between a radially outermost opening 450 and the radially innermost outlet mouth 44. The radially outermost opening 450 comprises a guide inlet 451 for fluid inlet. It is advantageously formed along a perimeter edge of the opening 450. This guide inlet 451 further facilitates the entry of the fluid. In the version given by way of example in Figures 1-7, the guide entry 451 comprises a convexity. In particular, guide entry 451 comprises an arched bevel.

The collar 30 develops in thickness in a radial direction. The thickness of the collar 30 is not constant along the first channel 4. For example, as illustrated by way of example in Figure 5, the thickness is smaller in a predetermined section interposed between the first and the second wall 41,42 . The thickness increases progressively as it moves towards the first and second wall 41,42.

The collar 30 comprises a first and a second face 301,302 which are at least partly parallel to each other and between which the annular surface 31 facing and surrounding the rotor 2 extends. The first and second wall 301, 302 are preferably flat .

The first channel 4 radially crosses the collar 30. In the version of Figures 1-7 the outlet mouth 44 is defined by an opening provided in the annular surface 31. In the version of Figures 8-10, the depth of the first channel 4 tends to be zero on the annular surface 31.

In general, however, the first channel 4, starting from the first face 301, projects into the interior of the collar 30, reducing the axial thickness thereof in that portion (note that as mentioned above the axial thickness of the collar, as indicated above, must be measured axially, that is, parallel to the axis 20 of rotation).

Advantageously, the first and the second wall 41,42 are reciprocally asymmetrical. In the version of Figures 8 10, a radially more internal terminal portion of the first and second wall 41, 42 are reciprocally convergent.

In the following, reference is made to the embodiment of Figures 1-7. In this case, the first wall 41, between the radially outermost opening 450 and the outlet mouth 44, extends along a first straight direction 410. The second wall 42, between the radially outermost opening 450 and the outlet mouth 44, extends along an arcuate line.

Moving from the radially outermost opening 450 towards the outlet mouth 44, the first wall 41 and a terminal portion of the second wall 42 diverge.

An imaginary intersection line is defined between:

- an extension 460 of the first wall 41 along the first straight direction 410;

- a plane 461 tangential to the intersection between the second wall 42 and the annular surface 31. The imaginary intersection line is external to the stator 3 (in figure 5 the extension 460 and the plane 461 are illustrated and it can be seen that they are intended to intercept each other externally of the stator 3).

A particular application of the present pump 1 is linked to the lubrication of the internal combustion engines of vehicles.

The collar 30 advantageously comprises a second channel 6 that contributes to an introduction of fluid between the rotor 2 and the stator 3. Advantageously the first and second channel 4, 6 are reciprocally symmetrical. This symmetry is observed with respect to an intermediate plane perpendicular to the axis 20 of rotation of the rotor 2. The second channel 6 involves only a part of the collar 30 and, when present, reduces the axial thickness of the collar 30 (as previously explained in axial thickness of the collar 30 must be measured in parallel to the direction of the axis of rotation 20).

The second channel 6 directs the fluid in such a way that it reduces a misalignment between the first fluid flow and the second fluid flow, already defined in the foregoing (ie a flow that transits in the stator 3 in front of the first channel 4 and is extracted by the rotor 2).

The second channel 6 advantageously comprises two lateral walls 96, 97 and a connecting surface 98 of the two lateral walls 96, 97. While moving radially from a more external position to a more internal position, the base surface 43 of the first channel 4 and the connection surface 98 of the second channel 6 are reciprocally divergent.

One or more of the characteristics described above with reference to the first channel 4 can be repeated with reference to the second channel 6. The collar 30 advantageously externally defines a leading edge that separates the flow of fluid and guides it towards the first and second channel 4, 6. In the maximum volume condition almost all the fluid sucked by the pump 1 transits through the first and second channel 4, 6. As the distance from the optimum maximum volume condition increases, the amount of fluid that could also divert the first and second channel 4, 6. This specification also reduces dynamic fluid losses by better guiding the fluid; This is also reflected in the best pump behavior with respect to cavitation.

The stator 3 illustrated in the version of Figures 1-7 is advantageously typically made of a metal material. The stator of Figures 8-10 has a shape such that it could also be made of a plastic material.

The objective of the present invention is therefore a system comprising:

- an internal combustion engine for vehicles;

- an engine lubrication system comprising a positive displacement pump having one or more of the characteristics described in the foregoing. During use the non-compressible fluid is introduced through the supply line 9 between the rotor 2 and the stator 3. The fluid flows into the chamber 34, transiting through the first channel 4 (and through the second channel 6, if it is Present). The first and the second channel 4, 6 direct the fluid in such a way as to reduce a misalignment with a current of fluid already present in the stator 3.

In this way the invention conceived makes it possible to achieve multiple advantages.

It consists of optimizing the shape of the stator, allowing to obtain a better volumetric efficiency and a lower risk of cavitation (that is, it allows higher rotor rotation speeds before finding cavitation phenomena). This is obtained by studying the stator profiles in order to minimize the "dead zones" in which the fluid recirculates.

The tests carried out by the Applicant have shown a 4% improvement in dynamic performance of pump fluid and a reduction in noise levels compared to pumps that have a conventional design and lack the claimed specifications.

In the particular sector of the automobile industry the pump of the present invention can be used to lubricate internal combustion engines, allowing a reduction in emissions and preventing power losses. Increasing attention to this problem area (especially, but not only, in the automotive sector) in recent years has led to the analysis and optimization of all pump components.

The invention as conceived is susceptible of numerous modifications, all falling within the scope of the appended claims.

Additionally, all the details can be replaced with other technically equivalent elements. In practice, all the materials used, as well as the dimensions, can be any according to the requirements.

Claims (15)

1. A positive displacement pump with variable displacement comprising: - a blade rotor (2); - a stator (3) comprising a collar (30) internally from which the rotor (2) can rotate; the stator (3) and a rotational axis (20) of the rotor (2) moving relative to each other in such a way that they vary the volume of the pump (1); the collar (30) defining at least a first channel (4) to allow or contribute to an introduction of fluid between the rotor (2) and the stator (3); reducing the first channel (4) an axial thickness of the collar (30) in an area in which it is formed; characterized because when moving from a radially more external position (991) to a radially more internal position (992), the first channel (4) defines a ramp (99) that reduces the depth of the first channel (4), said depth being measured in parallel to the axis (20) of rotation. 2. The pump according to claim 1, characterized in that the first channel (4) radially crosses the collar (30) between a radially more external opening (450) and a radially more internal outlet (44). 3. The pump according to claim 2, characterized in that the depth of the first channel (4), measured in parallel to the axis of rotation (20) is on average smaller in the outlet mouth (44) than in the opening ( 450) radially more external. 4. The pump according to claim 2 or 3, characterized in that said radially outermost opening (450) comprises a guide inlet (451) for fluid inlet. The pump according to claim 4, characterized in that the guide inlet (451) comprises a connection defining a convexity that develops along a perimeter edge of the radially outermost opening (450). The pump according to any one of the preceding claims, characterized in that the first channel (4) comprises a first and a second wall (41,42) which are reciprocally facing each other. The pump according to claim 6, characterized in that the collar (30) comprises an annular surface (31) that faces and surrounds the rotor (2); the minimum distance between the first and the second wall (41,42) measured along the annular surface (31) is less than 1/3 of the minimum length of a line which, placed completely on the annular surface (31) , surround the rotor (2). The pump according to claim 7, characterized in that the second wall (42) is arched and connected tangentially to said annular surface (31). The pump according to claim 7 or 8, characterized in that the depth of the first channel (4), measured in parallel to the axis of rotation (20) is zero in the annular surface (31). 10. The pump according to any one of claims 6 to 9, characterized in that the first and the second wall (41,42) are reciprocally asymmetrical. 11. The pump according to any one of claims 6 to 10, characterized in that it comprises a base surface (43) connecting the first and the second surface (41,42); increasing the axial thickness of the collar (30) on the base surface (43) progressively as it passes from the first to the second wall (41,42). The pump according to any one of claims 5 to 10, characterized in that the first channel (4) comprises a base surface (43) for connecting the first and the second wall (41, 42); said pump (1) comprising a second channel (6) which in turn comprises two lateral walls (96, 97) and a connecting surface (98) of the two lateral walls (96, 97); moving radially from a more external position to a more internal position, the base surface (43) of the first channel (4) and the connecting surface (98) of the second channel (6) being reciprocally divergent and executing a fluid routing. 13. The pump according to any one of the preceding claims, characterized in that the stator (3) defines a chamber (34) for housing the rotor (2); the stator (3) comprising a first and a second plane (311, 312) that are transverse to the axis (20) of rotation and which occlude the chamber (34), together with the collar (30), the pump (1) comprising a fluid supply conduit (9) that opens into the chamber (34); opening the supply conduit (9) in the chamber (34) through a suction opening (90) provided in the foreground (311); the first channel (4) facing and being located in said suction opening (90). 14. The pump according to claim 13, characterized in that the supply line (9) comprises a deflector (900) which generates on the sides of it a first and a second rail (901, 902) for the fluid flow, being the first and second lanes (901,902) divergent from each other; the suction opening (90) extending between a first and a second end (903, 904); the first end (903) facing a circumferential portion of the rotor (2) that is more downstream, with respect to the direction of rotation of the rotor (2), than the circumferential portion facing the second end (904); terminating the first rail (901) at the first end (903) of the suction opening (90); terminating the second rail (902) at the second end (904) of the suction opening (90); the first lane (901) having a larger passage section with respect to the second lane (902); the first rail (901) increasing a component of the fluid movement that travels through the conduit (9) that is oriented towards the direction of rotation of the rotor (2). 15. The pump according to any of the preceding claims, characterized in that the first channel (4) directs the fluid to increase the fluid component oriented in the direction of rotation of the rotor (2) such that it reduces a misalignment between the first fluid flow that comes from said first channel (4) and a second fluid flow that: intercepts the first flow, transits at the front of the first channel (4) and is extracted by the rotor (2).