CN112543845A

CN112543845A - Rotary displacement pump

Info

Publication number: CN112543845A
Application number: CN201980036706.4A
Authority: CN
Inventors: L·卡代杜
Original assignee: VHIT SpA
Current assignee: VHIT SpA
Priority date: 2018-05-30
Filing date: 2019-05-29
Publication date: 2021-03-23
Also published as: WO2019229106A1; IT201800005866A1; EP3803124B1; EP3803124A1

Abstract

The invention relates to a rotary displacement pump comprising: -a shaft (2) suitable for rotating about an axis of rotation; -a rotor (3); -means (5) for transmitting torque from the shaft (2) to the rotor (3). The rotor (3) comprises a first seat (31), said first seat (31) comprising a side wall (310), said side wall (310) in turn comprising a first flat portion (311). The transmission (5) comprises an annular structure (50) applied to the shaft (2) and removably connected to the rotor (3); the annular structure (50) in turn comprises at least one first projecting tab (51), said at least one first projecting tab (51) being engaged in the first seat (31) of the rotor (3) at least in one operating configuration of the pump. The first tab (51) includes at least one first planar surface (510). In the operating configuration, the first flat surface (510) is a thrust surface and is in contact with a first flat portion (311) of the wall (310) of the first seat (31).

Description

Rotary displacement pump

Technical Field

The invention relates to a rotary displacement pump, in particular a vane pump, for generating a pneumatic pressure and/or vacuum, in particular in a dry vacuum pump, i.e. a vacuum pump which is not lubricated by a fluid.

Background

Vane pumps of the type comprising a rotary shaft to which the rotor can be connected by means of a drive coupling are known in the prior art. The coupler is connected to the shaft in a manner that avoids relative rotation. The coupling has a ring from which extend two arms which engage in respective seats provided in the rotor.

According to a first constructive solution, the arms have a substantially circular cross section and a tapered longitudinal section due to the stamping deformation. According to a second constructive solution, the side wall of each arm has two opposite surfaces, arched with respect to each other and intended to be in contact with the flat surface of the respective rotor seat.

The coupler is obtained by precision casting, and the piece thus obtained is subjected to a plurality of machining operations by a machine tool (generally inside the bore of the ring coupler). This obviously slows down the manufacturing process, while requiring continuous machining operations that increase costs.

Disclosure of Invention

It is an object of the present invention to provide a pump which allows to optimize costs and to distribute the pressure acting on a surface.

Another object is to reduce wear and maintain good centering. The technical problem described and the aims specified are substantially achieved by a pump comprising the technical features defined in one or more of the appended claims.

Drawings

Further characteristics and advantages of the invention will become clearer from the non-limiting description provided by reference to a pump as shown in the attached drawings, wherein:

figure 1 shows a view of a shaft/rotor/coupler subassembly of a pump according to the invention; said subassembly being identified by reference numeral 1;

figure 2 shows a perspective view of a portion of the subassembly of the pump of figure 1;

figures 3, 4 and 5 show a perspective view, a front view and a cross-sectional view, respectively, of a rotor with a blade, which is a component of the solution shown in figure 1;

fig. 6 shows another component of the solution shown in fig. 1.

Detailed Description

The present invention relates to a rotary displacement pump, preferably a vane pump (which may also be a gear pump or another type of pump). Typically, the pump is a dry pump. Conveniently, the pump is a vacuum pump. For example, the pump may be used in a vehicle braking system. In a preferred solution, the pump is driven by an electric motor.

The pump includes:

-a shaft 2 adapted to rotate about an axis of rotation;

-a rotor 3. The rotor 3 is a member that allows the working fluid processed by the pump to move. Thus, the rotor 3 is in contact with the working fluid.

In the preferred version where the pump is a vane pump, the rotor 3 at least partially houses the vanes 4.

In this respect, the rotor 3 has a cavity 300 for accommodating the blade 4. Each of the cavities 300 extends between an inner radial position and an outer radial position. Advantageously, said cavity 300 is inclined with respect to a purely radial direction. The cavity 300 preferably passes completely through the rotor 3 in the axial direction. Fig. 4 shows a single one of the blades 4, although each cavity 300 accommodates one blade.

Advantageously, the rotor 3 is made of carbon-graphite. Conveniently, the rotor 3 is a disk-like element. The rotor 3 is preferably coaxial with the shaft 2.

The pump comprises a stator element, not shown in the drawings, which defines an opening for receiving the rotor 3. Thus, the rotor 3 rotates inside the opening. Said blades 4 protrude more or less from the rotor 3, depending on the position of each blade. Externally, the blades 4 are contacted by the stator elements.

The pump further comprises means 5 for transmitting torque from the shaft 2 to the rotor 3. In the solutions shown in fig. 1, 2 and 6, the transmission 5 comprises/coincides with a transmission coupling.

The rotor 3 comprises a first seat 31. The first seat 31 includes a side wall 310 (see fig. 3). The sidewall 310 includes a first flat portion 311 (shown in fig. 4). The side wall 310 advantageously also comprises a second flat portion 312 opposite the first flat portion 311 and advantageously comprises two connection zones at opposite ends of the first seat 31. The first seat 31 advantageously comprises an end wall 313. The first portion 311 lies in a first plane and the second portion 312 lies in a second plane parallel to the first plane.

The transmission 5 comprises an annular structure 50. The ring structure 50 is preferably obtained from a stainless steel plate. The annular structure is applied to the shaft 2. In particular, the shaft 2 is engaged in (and passes through) a bore 59 defined by the annular structure 50. Conveniently, the shaft 2 and the annular structure 50 are coupled by interference (coupled by interference). Thus, torque is transmitted by the shaft 2 to the annular structure 50, which in turn transmits torque to the rotor 3. The annular structure 50 is removably connected to said rotor 3. The annular structure 50 in turn comprises at least one first projecting tab 51 which engages in said first seat 31 of the rotor 3 at least in one operating configuration of the pump. Said protruding tabs 51 are used to transmit the movement of the annular structure 50 to the rotor 3.

The first tab 51 includes at least one first planar surface 510. The first tab 51 has an extension mainly in the longitudinal direction. The longitudinal direction of the first tab 51 extends in the axial direction. The first tab 51 includes a second flat surface 511 on the side opposite the first flat surface 510.

In a section orthogonal to said main direction of extension, the first tab 51 has a rectangular section. At the two vertices 55 of the orthogonal section (on the opposite side to the side where the cutting burr is possible), the corner is free of any burr due to the actual cutting process. Conveniently, in this section, the two vertices 55 are located at the ends of the first surface 510.

In the operating configuration, the first flat surface 510 is the surface that pushes the rotor 3 and is in contact with said first flat portion 311 of said wall 310 of the first seat 31. The direction of rotation of the shaft 2 is such that the first surface 510 presses the first portion 311 down. Conveniently, the second flat surface 511 faces the second portion 312 of the sidewall 310 in the operating configuration.

The first surface 510 is a region in contact with the rotor 3. The first surface 510 has a main longitudinal extension extending parallel to the axis of rotation of the shaft 2.

Similarly, the first surface 510 has a radial extension component that is greater than a tangential extension component (which may even be zero). The radial extension is evaluated with respect to the axis of rotation of the shaft 2. The tangential component is evaluated tangentially to the circumferential direction centered on the axis of rotation of the shaft 2. This orientation enables torque to be transmitted to the rotor 3, reducing local stresses and improving specific pressure peaks (due to the increased contact area).

Conveniently, the first surface 510 lies in a plane that also contains the axis of rotation of the shaft 2.

In a preferred solution, the first tab 51 is a portion of sheet material having a thickness of less than 1.5 mm. For example, the first tab 51 extends longitudinally over a length of between 5 and 9 millimeters. Preferably, the first tab 51 has a width of between 2 and 4 millimeters.

The annular structure 50 comprises a central crown 500 from which extends an L-shaped structure 501 defining said first tab 51.

Conveniently, the annular structure 50 comprises a second projecting tab 52, which, in the operating configuration, is engaged in a second seat 32 provided in the rotor 3. The first and

second tabs

51, 52 are advantageously located in diametrically opposite positions.

The description made with respect to the first tab 51 may be repeated for the second tab 52. Similarly, the description made with respect to the first seat 31 may be repeated for the second seat 32. In particular, the description made with respect to the first tab 51 and its interaction with the first seat 31 can be repeated for the second tab 52 and its interaction with the second seat 32. For example, the second tab 52 may include a push surface 520. The thrust surface 520 is flat. The thrust surface is entirely contained in a plane containing the first surface 510 and the axis of rotation of the shaft 2.

There may also be other tabs projecting from the crown 500, which engage in corresponding seats provided in the rotor 3.

The rotor 3 preferably comprises a housing 30, in which operating configuration the central crown 500 is completely inserted in the housing 30. The first seat 31, in which the first tab 51 is engaged, extends from the housing 30 parallel to the axis of rotation of the shaft 2.

Conveniently, the rotor 3 comprises an axial portion 56, the radial clearance with respect to the shaft 2 corresponding to which is minimal. The first tab 51 extends inside the first seat 31 only in correspondence (or at least up to 90%) with said axial portion 56, the radial clearance corresponding to which is minimal. A similar situation is also true of second tab 52 extending within second seat 32. The purpose of these arrangements is to ensure that the torque transmission to the rotor 3 through the device 5 (coupling) takes place in the region where the rotor 3 is well guided by the shaft 2, in order to prevent small shape errors from causing misalignment.

The invention also relates to a method for implementing a pump. Conveniently, the pump includes one or more of the features described above.

The method comprises the step of realizing a ring-shaped structure 50. This is advantageously carried out in a progressive stamping die working on a "strip of sheet material" in which a series of operations are carried out in succession. As the part exits the progressive stamping die, no machining is performed to remove additional swarf from the ring structure 50.

This makes manufacture faster and less costly. The step of realising the ring structure 50 comprises the following steps: a sheet of material (which is generally at least initially flat) is shaped by cutting and stretching to form a central crown 500 from which extends at least one side wall 501. At least in this step, the central crown 500 advantageously remains connected to the surrounding sheet material by means of at least one connection point which is not cut in this step (this only occurs at a later time). The stretching determines a thickening of the central crown 500, which becomes thicker than the initial sheet. This helps to transmit torque from the shaft 2.

The step of realising the annular structure 50 comprises bending the lateral wall 501 to define the first tab 51. This includes bending the arm 501 through an angle between 70 ° and 110 °, preferably 90 °.

Conveniently, the longitudinal extension of the lateral wall 501 has two curves (see fig. 6):

a first curve 504 indicating a transition from a radial extension to a substantially tangential extension;

a second curve 505 is determined which transitions from a substantially tangential extension to an extension parallel to the rotation axis of the shaft 2.

Conveniently, the step of realising the annular structure 50 also comprises the step of bending (typically 90 °) at least one additional arm 502 extending from the central crown 500. The additional arm defines a second tab 52. The separation of the "sheet strips" takes place in the next realisation step.

The method further comprises the step of inserting a shaft 2 into the hole 59 of the ring structure 50. This occurs after the ring structure 50 is completed. The shaft 2 and the ring structure 50 are typically connected by interference.

The method further comprises the step of inserting the shaft 2 into the rotor 3 (connecting the ring structure 50 and the rotor 3). This comprises the step of inserting the first tab 51 into the first seat 31 of the rotor 3 (and advantageously also the second tab 52 into the second seat 32).

The present invention provides significant advantages.

First, the present method can limit manufacturing costs by achieving coupling by punching the plate material without additional processing. Furthermore, the contact area is improved, thereby reducing the specific pressure (this is considerable in particular in the case of rotors made of carbon-graphite, which has the best thermal resistance, but mechanical properties inferior to steel).

Another significant advantage is that there is good centering between the rotor 3 and the shaft 2, while limiting wear, due to the reduced clearance which allows sufficient dynamic vibration to compensate for orthogonality errors in manufacture; this is also due to the above-described configuration of the coupler 5.

The invention thus conceived is susceptible of numerous modifications and variations, all falling within the characteristic inventive concept. Moreover, all the details may be replaced with other technically equivalent elements. In practice, all materials and dimensions used may be as desired.

Claims

1. A positive displacement pump, comprising:

-a shaft (2) adapted to rotate about an axis of rotation;

-a rotor (3);

-means (5) for transmitting torque from the shaft (2) to the rotor (3); the rotor (3) comprises a first seat (31) comprising a side wall (310) comprising a first flat (311) portion;

the transmission (5) comprises an annular structure (50) solidly constrained to the shaft (2) and connected to said rotor (3); said annular structure (50) in turn comprises at least one first protruding tab (51) engaged in said first seat (31) of the rotor (3) at least in one operating configuration of the pump;

the first tab (51) comprises at least one first flat surface (510);

characterized in that, in said operating configuration, said first flat surface (510) is a thrust surface and is in contact with said first flat portion (311) of the side wall (310) of the first seat (31).

2. Pump according to claim 1, characterized in that the first tab (51) has a radial extension component greater than a tangential extension component, the radial extension being evaluated with respect to the axis of rotation of the shaft (2), the tangential component being evaluated with respect to a circumferential tangency centered on the axis of rotation of the shaft (2).

3. Pump according to claim 1 or 2, characterized in that it comprises at least one second projecting tab (52) which, in the operating configuration, engages in a second seat (32) provided in the rotor (3).

4. A pump according to claim 1 or 2 or 3, wherein the first tab (51) is part of a sheet of material having a thickness of less than 1.5 mm.

5. Pump according to any one of the preceding claims, characterized in that the rotor (3) is made of carbon-graphite, the annular structure (50) being obtained from a stainless steel sheet.

6. Pump according to any one of the preceding claims, characterized in that 27.r9005v.12.it.8ing. alberto monell (reg.no.1342b) 2: the ring-shaped structure (50) comprises a central crown (500) from which a first tab (51) extends.

7. Pump according to claim 6, characterized in that the first tab (51) is integrated in an L-shaped structure (501) which extends from a central crown (500).

8. Pump according to claim 6 or 7, characterized in that the rotor (3) comprises a housing (30) in which the central crown (500) is fully inserted in the operating configuration; the first seat (31) engaged with the first tab (51) extends from the housing (30) parallel to the axis of rotation of the shaft (2).

9. Method for implementing a pump according to claim 6 or 7 or 8, characterized in that it comprises the following steps:

a) -realising said annular structure (50) comprising the following steps:

-shaping a sheet of material by cutting and stretching to form a central crown (500) from which at least one lateral wall (501) extends;

-bending the side wall (501) to define said first tab (51);

b) -inserting the shaft (2) into a hole (59) of the annular structure (50);

c) -inserting said first tab (51) into a first seat (31) of said rotor (3).

10. Method according to claim 9, characterized in that said stretching determines a thickening of said central crown (500), the thickness of said central crown becoming greater than the thickness of the initial sheet.