EP3194723B1

EP3194723B1 - Rotary pump

Info

Publication number: EP3194723B1
Application number: EP15774989.6A
Authority: EP
Inventors: Leonardo Cadeddu
Original assignee: VHIT SpA
Current assignee: VHIT SpA
Priority date: 2014-09-15
Filing date: 2015-09-14
Publication date: 2023-03-08
Anticipated expiration: 2035-09-14
Also published as: WO2016042460A1; EP3194723A1

Description

Technical field

The present invention relates to a rotary pump for fluids, and more specifically it relates to a lid for a rotary pump.
Preferably, the invention is applied in pumps using a rotor made of plastic material.
More preferably, the invention is applied in the so-called single-vane pumps, i.e. pumps in which the rotor includes a single vane, and the following description mainly refers to this preferred application.

Prior Art

Single-vane rotary pumps are known in the automotive field, where they are often used as vacuum pumps.
Single-vane rotary pumps include a body, defining a chamber inside which a rotor rotates, and a closing lid. The rotor has a diametrical slot in which a vane is mounted. The chamber is divided by the rotor and the vane into a suction environment and a compression environment between which a pumped fluid is displaced.
More particularly, pumps using a rotor made of plastic material are known among the single-vane rotary pumps. Such pumps generally require a double guide for the rotary motion of the rotor, namely a first guide formed in the pump body and a second guide formed in the pump lid, the lid being made, according to the prior art, of die-cast metal.
Actually, the rotor made of plastics is to be guided so as to form a structure closed at both sides of the socket of the vane housing, for reasons of mechanical strength, in particular at cold starts and in case of counter-rotations.
For instance, document US 5,181,843 discloses a rotary pump with double guide, as typically provided for by the prior art for pumps where the rotor can be made, for instance, of plastics.
Document WO 2009/109282 A1 discloses a rotary pump according to the preamble of claim 1.
A problem of the prior art is due to the axial bulk of the pump, caused by the presence of the guide formed in the lid, if the guide is made of die-cast metal.
Another problem of the prior art is due to the weight of the pump, caused by the fact that the lid in which the guide is formed is made of die-cast metal.
The Applicant has noticed that the prior art generally fails in limiting the axial bulk and reducing the overall weight of single-vane rotary pumps using a rotor made of plastic material.
In synthesis, the Applicant has noticed that the axial bulk and the weight of the pumps often make installation of same difficult and cause an increase in installation costs.

Description of the Invention

It is an object of the invention to provide a rotary pump having a rotor made of lightweight material, for instance plastic material, which pump solves the technical problems described above.
According to the present invention, this object is achieved through a rotary pump having the features set forth in the appended claims.
The claims are integral part of the technical teaching provided herein in respect of the invention,
The following synthetic description of the invention is given in order to provide a basic understanding of some aspects of the invention.
In accordance with the invention, the rotary pump includes a lid made of metal sheet in which a guide for the rotary motion of the rotor is formed.
In accordance with another feature of the present invention, the guide is achieved by means of a guiding hole formed in the lid, and the hole is sealed in fluid-tight manner by a cap of thin metal sheet.
In accordance with a further feature of the present invention, the lid and the cap are fastened together by means of adhesives, with or without interference fit between the lid and the cap, or by means of braze welding.
In accordance with yet another feature of the present invention, the lid is fastened to a pump body by means of adhesives, with or without use of centring elements formed in the lid and arranged to interference fit with the pump body.

Brief Description of the Figures

The above and other features and advantages of the present invention will become apparent from the following description of a preferred embodiment made by way of a non-limiting example with reference to the accompanying drawings, in which elements denoted by a same or similar numerical reference correspond to components having the same or similar function and construction, and in which:

Fig. 1 shows a plan view of a single-vane rotary pump without the lid;
Fig. 2 shows a plan view of the pump shown in Fig. 1 with the lid;
Fig. 3 shows a cross-sectional view of the pump shown in Fig. 2 taken along line A - A, in a 2:1 scale; and
Fig. 4 shows a detail Z of the cross-sectional view shown in Fig. 3, in a 5:1 scale.

Description of Preferred Embodiments

Referring to Fig. 1, a pump 100 according to the invention is for instance a single-vane rotary vacuum pump.
Pump 100 has a body 101 with an inner wall 114. Pump body 101 defines, together with a pump lid 106, a pumping chamber 115, with preferably elliptical cross-section.
A rotor 102 is located inside pumping chamber 115. Rotor 102 used in the present invention is a vane rotor, preferably a single-vane rotor. In the exemplary embodiment shown, single-vane rotor 102 has a radial slot where a vane 103, radially slidable within the same slot, is mounted.
Rotor 102 is made of a lightweight material, for instance thermoplastic or thermosetting or even composite material.
Suction openings 104, 105 are formed in inner wall 114 of pump body 101. In case of use of pump 100 in the automotive field, such openings, equipped with non-return valves, known per se, can be connected to components requiring a vacuum for operating, such as for instance brake booster, EGR (Exhaust Gas Recirculation) valves or other motor vehicle services.
An exhaust opening 116 is further formed in inner wall 114 of the pump, in order to exhaust a fluid having been sucked and compressed.
A dragging joint 113 is located externally to pump body 101 and can be connected to a first end of rotor 102, the latter being arranged to receive a rotary motion from a driving member (not shown).
Pump body 101 includes, preferably in a proximal zone with respect to dragging joint 113, a first guide 109 arranged to guide the rotary motion of rotor 102 (Fig. 3).
According to the invention, lid 106 of pump 100 is made of metal sheet, for instance metal sheet having a thickness preferably in the range 2.5 mm to 4 mm.
In accordance with the invention, pump lid 106 includes a second guide 110 arranged to guide the rotary motion of rotor 102 (Figs. 3 and 4).
The second guide 110 consists of a guiding hole formed in metal sheet lid 106 (Fig. 3).
Preferably, guiding hole or support 110 is made, in known manner, by fine blanking and/or by chamfering.
The second guide 110 formed in lid 106, for instance in the manner described above, is arranged to cooperate with the rotor over its whole thickness (Fig. 4).
According to the invention, guiding hole or support 110 is closed by a cap 111, for instance a cap made of thin metal sheet having a thickness in the range 0.6 mm to 1 mm (Figs. 3 and 4).
In the context of the description of the present invention, the term "metal sheet" used for both lid 106 and cap 111 denotes a metal sheet brought to a predetermined thickness by rolling.
Fastening of cap 111 to pump lid 106 is obtained, through adhesives with high thermal and mechanical strength and with sealing power, applied at least onto portions of the contact surfaces between cap 111 and pump lid 106, said surfaces being denoted by symbols "x" in Fig. 4.
Possible adhesives are for instance epoxy glues, in particular two-component epoxy glues, such as for instance araldite^®.
Other possible adhesives are ceramic or acrylic glues.
In other embodiments, fastening between cap 111 and pump lid 106 is obtained by means of one of the adhesives mentioned above and interference fit between cap 111 and lid 106.
In yet other embodiments, fastening between cap 111 and pump lid 106 is obtained by means of low-temperature braze welding, of known type.
In accordance with a further embodiment, the second guide or support is formed in lid 106 by means of indentation or half-blanking. The indented or half-blanked portion obtained in this manner is arranged to cooperate with rotor 102 by guiding it when the rotor is rotating.
In accordance with a preferred embodiment, lid 106 made in accordance with the present invention is fastened to body 101 by means of adhesives similar to those described in connection with the fastening of the cap to the lid.
For instance, the adhesives employed are applied at least onto portions of contact surfaces between the cap and the pump body, said surfaces being denoted by symbols "+" in Fig. 3.
Preferably, centring elements 112 are provided in the cap and are arranged to interference fit with recesses 119 formed in pump body 101, thereby assisting in fastening lid 106 to body 101.
Centring elements 112 are formed for instance by means of half-blanking or indentation of lid 106.
In accordance with other embodiments, fastening between cap 106 and pump body 101 is obtained by means of fastening screws or by means of adhesives and positioning screws.
Even though the invention has been described in detail with reference to a rotary vacuum pump with a single-vane rotor made of plastics, the invention itself can be applied to any single-vane or multiple-vane rotary pump for conveying a fluid from a first to a second working environment (for instance an oil pump, a water pump etc.).
Hereinafter, the operation of the pump disclosed above is described with reference to Figs. 1 to 4.
Pump 100 is connected, in known manner, to a driving member (for instance, a drive shaft or a cam shaft of a motor vehicle) by means of dragging joint 113. Dragging joint 113 is coupled to rotor 102 and transmits the rotary motion of the driving member to the rotor itself.
In the exemplary embodiment shown in Fig. 1, rotor 102 rotates counter-clockwise. During rotation, the ends of rotor vane 103 slide substantially in contact with inner wall 114 of pumping chamber 115, so as to cyclically divide chamber 115, in fluid-tight manner, into at least one suction area, with variable volume, and at least one compression and exhaust area, with variable volume.
In accordance with the preferred embodiment, rotor 102, during its rotary motion, is guided either by the two guides 109, 110, described above, or by the first guide 109, formed in pump body 101, and by the second guide 110, formed in metal sheet lid 106 of the pump.
Use of the rotor made of plastics requires a double guide or support for the rotary motion of the rotor, so that forming the second guide 110 in metal sheet lid 106 of the pump, in accordance with the present invention, allows sensibly reducing the axial bulk of the pump.
The axial bulk reduction is moreover achieved thanks to other features included in further embodiments of the pump of the present invention, such as:

fastening lid 106 to the pump body through adhesives and interference fit between centring elements 112 in the lid and recesses 119 in body 101, hence without use of screws (the heads of which contribute to the bulk increase);
the use of metal sheet cap 111 fastened to lid 106 through interference fit and/or adhesives.

Advantageously, centring elements 112 provided in accordance with variant embodiments of the present invention, by cooperating with recesses 119 formed in pump body 101, make centring of the lid relative to the body easier and, through the interference, form further means for connecting the parts.
A further advantage of the present invention is due to the lower weight of the metal sheet lid with respect to a conventional lid of die-cast metal.
Advantageously, reducing the axial bulk and the weight of the pump allows an easier installation of the pump of the present invention.
Lastly, the choice of a lid made of metal sheet also entails an economic advantage thanks to the reduction in the production costs.
It is clear that the above description is given only by way of non-limiting example and that changes and modifications are possible without departing from the scope of invention as defined by the following claims.

Claims

A rotary pump comprising:
- a body (101) defining a pumping chamber (115) and comprising at least one suction opening (104, 105) and at least one exhaust opening (116),

- a rotor (102) rotatably mounted inside said pumping chamber (115) and having at least one vane (103),

- a first guide (109) provided in the pump body (101) and arranged to guide, in use, a first end of said rotor (102),

- a lid (106) including a second guide (110) having a guiding hole which has certain hole thickness and which is arranged to cooperate, in use, with a second end of said rotor;
wherein said lid (106) is made of a metal sheet having a predetermined thickness, and in that it further comprises a cap (111), which is made of a metal sheet having a thickness smaller than the thickness of said lid and is arranged to seal in fluid-tight manner said guiding hole,

the pump being characterized in that said cap (111) is fastened to said lid (106) by means of:
- high strength adhesives having sealing power, or

- high strength adhesives having sealing power, and interference fit between said cap (111) and said lid (106), or

- braze welding of said cap (111) to said lid (106),

in that said cap (111) comprises a peripheral stepped portion and is fitted on top of a corresponding stepped portion of the lid (106), said high strength adhesives having sealing power or said braze welding being applied at least onto portions of contact surfaces (x) between said peripheral stepped portion of the cap (111) and said corresponding stepped portion of the lid (106),

and in that said guiding hole of said second guide (110) is arranged to cooperate with said second end of said rotor (102) over its whole hole thickness.
The pump according to claim 1, wherein said lid is made of a metal sheet having a thickness in the range 2.5 mm to 4 mm and said cap is made of a metal sheet having a thickness in the range 0.6 mm to 1 mm.
The pump according to claim 1 or 2, wherein said lid (106) and said body (101) are fastened together by means of:
- high strength adhesives having sealing power, or

- high strength adhesives having sealing power and fastening screws, or

- fastening screws.
The pump according to any one of claims 1 to 3, wherein said lid (106) comprises centring elements (112) and said body (101) comprises recesses (119) matching said centring elements.
The pump according to claim 4, wherein said lid (106) and said body (101) are fastened by means of high strength adhesives having sealing power and interference fit between said centring elements (112) in the lid (106) and said recesses (119) in the body (101).
The pump according to any one of claims 1 to 5, wherein said pump (100) is a vacuum pump and said rotor is made of a material selected out of the group consisting of thermoplastic material, thermosetting material or composite material.