Automotive vacuum pump

The present invention is directed to an automotive vacuum pump, in particular to a rotary vane vacuum pump for providing vacuum to a motor vehicle brake booster.

Automotive vacuum pumps can be driven mechanically, typically by the internal combustion engine, or they can be driven electrically by an integrated electric motor. Automotive vacuum pumps are mainly used to provide vacuum to a brake booster of a braking system of the motor vehicle, in particular for providing vacuum to a vacuum chamber of the brake booster. The vacuum pump can be the only vacuum source for the brake booster or can be used in combination with other vacuum sources as for example an intake system of the internal combustion engine.

WO 2019/034256 Al discloses an automotive vacuum pump which comprises a pumping chamber, a first silencing chamber which is fluid ica I ly connected with and downstream of the pumping chamber, a second silencing chamber which is fluidically connected with and downstream of the first silencing chamber, and a pump outlet which is fluidically connected with and downstream of the second silencing chamber. The automotive vacuum pump comprises a pump rotor which is configured to rotate within the pumping chamber so as to pump a gas from the pumping chamber through the first silencing chamber and the second silencing chamber to the pump outlet. The automotive vacuum pump comprises a pumping chamber cover body which separates the pumping chamber from the first silencing chamber. The pumping chamber cover body comprises a pumping chamber outlet opening which fluidically connects the pumping chamber with the first silencing chamber. The pumping chamber cover body comprises an integral second silencing chamber outlet tube element which defines a second silencing chamber outlet channel fluidically connecting the second silencing chamber with the pump outlet. The pumping chamber cover body comprises a protruding structure which radially defines the first silencing chamber. The automotive vacuum pump comprises a flat silencing chambers separation body which is attached to the protruding structure of the pumping chamber cover body and separates the first silencing chamber from the second silencing chamber.

The complex-structured pumping chamber cover body of the disclosed automotive vacuum pump however must be manufactured by casting, which is relatively complex and requires relatively expensive equipment.

An object of the present invention is therefore to provide a relatively cost- effective automotive vacuum pump.

This object is achieved with an automotive vacuum pump with the features of claim 1.

Hereafter, unless otherwise defined, an axial direction is parallel to an axis of rotation of a pump rotor of the automotive vacuum pump, a radial direction is perpendicular to the axis of rotation of the pump rotor, a transverse plane is transverse to the axis of rotation of the pump rotor, and a body is made of a single piece.

The automotive vacuum pump according to the present invention is provided with a pump inlet, with a pump outlet and with a plurality of chambers which are arranged fluidically between the pump inlet and the pump outlet. The automotive vacuum pump according to the present invention in particular comprises a pumping chamber which is fluidically connected with and downstream of the pump inlet, a first silencing chamber which is fluidically connected with and downstream of the pumping chamber, and a second silencing chamber which is fluidically connected with and downstream of the first silencing chamber as well as fluidically connected with and upstream of the pump outlet. The pumping chamber is typically substantially cylindrical and radially defined by a substantially ring-shaped pumping chamber sidewall body. The volumes and geometries of the two silencing chambers and of their fluidic connections are typically optimized with regard to minimizing noise caused by the pressure pulsations which always occur during normal pumping operation. The inside surface of one or both of the silencing chambers can be provided with a special sound-absorbing surface structure.

The automotive vacuum pump according to the present invention is also provided with a pump rotor which is arranged within the pumping chamber. The pump rotor is configured to rotate within the pumping chamber so as to suck a gas, typically air, via the pump inlet into the pumping chamber and pump the gas from the pumping chamber through the first silencing chamber and the second silencing chamber to the pump outlet. Preferably, the pump rotor comprises a rotor body which is arranged eccentrically within the pumping chamber and which comprises several radially slidable rotor vanes. During pump operation, the rotor vanes are in touching radial contact with the pumping chamber sidewall body and define several rotating pumping-chamber compartments whose volume varies within one pump rotor revolution.

The automotive vacuum pump according to the present invention is also provided with a pumping chamber cover body which separates the pumping chamber from the first silencing chamber, i.e., the pumping chamber and the first silencing chamber both are at least partially defined by the pumping chamber cover body. The pumping chamber cover body typically extends substantially in a transverse plane and defines each of the pumping chamber as well as the first silencing chamber at one axial side. The pumping chamber cover body is typically provided with a completely flat pumping-chamber-sided surface which is in direct frictional contact with the pump rotor.

The pumping chamber cover body is provided with at least one pumping chamber outlet opening which fluidically connects the pumping chamber with the first silencing chamber. During pumping operation, the gas is discharged from the pumping chamber into the first silencing chamber via the at least one pumping chamber outlet opening. A check valve can be provided at the pumping chamber outlet opening so as to prevent backflow of the gas from the first silencing chamber into the pumping chamber via the pumping chamber outlet opening.

The pumping chamber cover body is also provided with a second silencing chamber outlet opening which is arranged at a radially outer region of the pumping chamber cover body, in particular radially outwardly of that region of the pumping chamber cover body which defines the pumping chamber. The second silencing chamber outlet opening fluidically connects the second silencing chamber with the pump outlet. During pumping operation, the gas is discharged from the second silencing chamber outlet opening toward the pump outlet via the second silencing chamber outlet opening. The second silencing chamber outlet opening is preferably provided with a substantially circular transverse cross-section.

The automotive vacuum pump according to the present invention is also provided with a silencing chambers separation body which is attached to that axial side of the pumping chamber cover body which is opposite to the pumping chamber. The silencing chambers separation body separates the first silencing chamber from the second silencing chamber, i.e., the first silencing chamber and the second silencing chamber both are at least partially defined by the silencing chambers separation body.

The silencing chambers separation body according to the present invention is provided with an integral second silencing chamber outlet tube element which is arranged at the second silencing chamber outlet opening of the pumping chamber cover body and projects into the second silencing chamber. The second silencing chamber outlet tube element defines a second silencing chamber outlet channel which leads to the second silencing chamber outlet opening, and thus fluid ica lly connects the second silencing chamber with the pump outlet. The second silencing chamber outlet tube element is preferably provided with a circular transverse crosssection, wherein an inner transverse diameter of the second silencing chamber outlet tube is preferably substantially equal to a transverse diameter of the second silencing chamber outlet opening. The second silencing chamber outlet tube element preferably extends substantially perpendicular to a surface of the pumping chamber cover body so that the silencing chambers separation body can be manufactured by deep drawing and thus relatively cost-effectively.

The silencing chambers separation body according to the present invention allows the pumping chamber cover element to be designed without any axially protruding structures at that axial side of the pumping chamber cover body which is opposite to the pumping chamber. This allows the pumping chamber cover element to be manufactured relatively cost- effectively and thus allows to provide a relatively cost-effective automotive vacuum pump.

Preferably, the silencing chambers separation body is provided with a flange portion which extends substantially in a transverse plane and radially surrounds the first silencing chamber, wherein the second silencing chamber outlet tube element is arranged at the flange portion. The silencing chambers separation body is attached to the pumping chamber cover body in such a way that the flange portion is in direct axial contact with the surface of the pumping chamber cover body. The flange portion provides a relatively large-area contact between the silencing chambers separation body and the pumping chamber cover body which achieves a sufficient fluidic sealing without the need for additional sealing means. The flange portion furthermore allows the silencing chambers separation body to be attached to the pumping chamber cover body in a reliable and easy- to-mount manner using screw connections.

More preferably, the flange portion comprises at least one screw opening through each of which extends a screw that secures the silencing chambers separation body to the pumping chamber cover body, wherein the flange portion is designed to be bent away from the pumping chamber cover body in the vicinity of the at least one screw opening if the respective screw is not tightened. As the screw is tightened the bent-away flange portion is elastically deformed, creating a preload that presses the flange portion against the pumping chamber cover body. This provides a well-sealed contact between the flange portion and the pumping chamber cover body.

Preferably, the first silencing chamber is completely defined by the pumping chamber cover body and the silencing chambers separation body so that no further elements are required to separate the first silencing chamber from the second silencing chamber. This allows the automotive vacuum pump to be made of a relatively small number of components, resulting in relatively low material costs as well as relatively small number of assembly steps. Preferably, the silencing chambers separation body is substantially domeshaped so that the silencing chambers separation body does not have any sharp edges. This provides particularly good silencing properties of the silencing chambers and furthermore allows simple and reliable manufacture of the silencing chambers separation body by deep drawing.

Preferably, the silencing chambers separation body is a deep-drawn sheet metal part which can be manufactured relatively cost-effective.

Preferably, the silencing chambers separation body comprises an integral first silencing chamber outlet tube element which defines a first silencing chamber outlet channel fluidically connecting the first silencing chamber with the second silencing chamber. The connection tube element preferably extends substantially perpendicular to a surface of the pumping chamber cover body so that the silencing chambers separation body can be manufactured by deep drawing and thus relatively cost-effectively. The first silencing chamber outlet tube element provides good silencing properties of the silencing chambers.

More preferably, the first silencing chamber outlet tube element projects into the first silencing chamber. This provides particularly good silencing properties of the silencing chambers.

Preferably, the pumping chamber cover body is flat and plate-shaped which allows the pumping chamber cover body to be manufactured simply and cost-effectively for example by punching out the pumping chamber cover body from a metal plate.

An embodiment of the present invention is described below with reference to the enclosed figures, showing: Figure 1 a sectional view of an axial end portion of an automotive vacuum pump according to the present invention,

Figure 2 a top view of a pumping chamber cover body of the automotive vacuum pump of figure 1,

Figure 3 a perspective view of a silencing chambers separation body of the automotive vacuum pump of figure 1, and

Figure 4 an enlarged section of Figure 1 which shows a flange portion of the silencing chambers separation body, but in a state in which screws that secure the silencing chambers separation body are not tightened.

Fig. 1 shows an axial end portion of an automotive vacuum pump 10 with a motor chamber 12, a pumping chamber 14, a first silencing chamber 16, a second silencing chamber 18 and a pump outlet 20. The pumping chamber 14 is fluidically connected with and downstream of a pump inlet (not shown), the first silencing chamber 16 is fluidically connected with and downstream of the pumping chamber 14, the second silencing chamber 18 is fluidically connected with and downstream of the first silencing chamber 16 as well as fluidically connected with and upstream of the pump outlet 20.

The pumping chamber 14 is substantially cylindrical. The pumping chamber 14 is defined at a motor-chamber-sided axial side by a flat and plate-shaped pumping chamber base body 22 and at a first-silencing- chamber-sided axial side by a flat and plate-shaped pumping chamber cover body 24. The pumping chamber 14 is radially defined by a substantially ring-shaped pumping chamber sidewall body 26. The first silencing chamber 16 is completely defined by the pumping chamber cover body 24, which separates the first silencing chamber 16 from the pumping chamber 14, and by a silencing chambers separation body 32, which separates the first silencing chamber 16 from the second silencing chamber 18.

The second silencing chamber is substantially defined by the pumping chamber cover body 24, the silencing chambers separation body 32 and by a housing cover body 33.

The pumping chamber base body 22, the pumping chamber sidewall body 26 and the pumping chamber cover body 24 each comprise a second silencing chamber outlet opening 221,261,241, each of which partially defines an outlet channel 28 fluidically connecting the second silencing chamber 18 with the pump outlet 20.

The pumping chamber cover body 24 also comprises a pumping chamber outlet opening 242 which fluidically connects the pumping chamber 14 with the first silencing chamber 16. The pumping chamber cover body 24 is a flat and plate-shaped punched-part which is punched out from a metal plate.

A check valve arrangement 30 is arranged at the first-silencing-chamber- sided side of the pumping chamber outlet opening 242 in such a way that it allows fluid flow from the pumping chamber 14 into the first silencing chamber 16 but prevents fluid backflow from the first silencing chamber 16 into the pumping chamber 14.

The silencing chambers separation body 32 is a substantially dome-shaped deep-drawn sheet metal part. The silencing chambers separation body 32 is attached to an axial side of the pumping chamber cover body 24 which is opposite the pumping chamber 14 by three screws 34. The silencing chambers separation body 32 comprises a flange portion 321 which extends substantially in a transverse plane and radially surrounds the first silencing chamber 16.

The flange portion 321 comprises three screw opening 322, through each of which extends one of the screws 34 that secure the silencing chambers separation body 32 to the pumping chamber cover body 24. As exemplified in Fig. 4, the flange portion 321 is designed in such a way that it is bent away from the pumping chamber cover body 24 in the vicinity of the screw openings 322 if the screws 34 are not tightened.

The silencing chambers separation body 32 comprises an integral second silencing chamber outlet tube element 323. The second silencing chamber outlet tube element 323 is arranged at the flange portion 321 and in direct vicinity to the second silencing chamber outlet opening 241 of the pumping chamber cover body 24. The second silencing chamber outlet tube element 323 extends substantially perpendicular to the pumping chamber cover body 24 and projects into the second silencing chamber 18. The second silencing chamber outlet tube element 323 defines a second silencing chamber outlet channel 324 leading from the second silencing chamber 18 to the second silencing chamber outlet opening 241 of the pumping chamber cover body 24.

The silencing chambers separation body 32 also comprises an integral first silencing chamber outlet tube element 325 which defines a first silencing chamber outlet channel 326 which fluidically connects the first silencing chamber 16 with the second silencing chamber 18. The first silencing chamber outlet tube element 325 is arranged at a substantially flat center part 327 of the dome-shaped silencing chambers separation body 32. The first silencing chamber outlet tube element 325 extends substantially perpendicular to the pumping chamber cover body 24 and projects into the first silencing chamber 16.

The automotive vacuum pump 10 comprises a pump rotor 36 which is arranged within the pumping chamber 14. The pump rotor 36 is driven by an electric motor (not shown) which is arranged within the motor chamber 12. The pump rotor 36 is configured to rotate within the pumping chamber 14. The pump rotor 36 and the pumping chamber 14 are designed in such a way that a gas is sucked into the pumping chamber 14 via the pump inlet and pumped from the pumping chamber 14 via the first silencing chamber 16 and the second silencing chamber 18 to the pump outlet 20 as the pump rotor 36 rotates during operation of the automotive vacuum pump 10.

Reference List

10 automotive vacuum pump

12 motor chamber

14 pumping chamber

16 first silencing chamber

18 second silencing chamber

20 pump outlet

22 pumping chamber base body

221 second silencing chamber outlet opening

24 pumping chamber cover body

241 second silencing chamber outlet opening

242 pumping chamber outlet opening

26 pumping chamber sidewall body

261 second silencing chamber outlet opening

28 outlet channel

30 check valve arrangement

32 silencing chambers separation body

321 flange portion

322 screw openings

323 second silencing chamber outlet tube element

324 second silencing chamber outlet channel

325 first silencing chamber outlet tube element

326 first silencing chamber outlet channel

327 center part

33 housing cover body

34 screws

36 pump rotor