Vane pump

Abstract

A vane pump with a pump housing in which a cam ring is constructed or arranged, and wherein a rotor is provided that is mounted in the cam ring so that it can rotate about a rotational axis , wherein the cam ring has an inner contour with a variable radius that varies between a maximum radius and a minimum radius in the circumferential direction about the rotational axis , wherein, in the radial gap between the inner contour and the rotor , a number of lift sections is constructed with pump chambers constructed in these sections, and wherein vane elements are mounted on the rotor , wherein these elements slide against the inner contour of the cam ring and limit the pump chambers in the circumferential direction. According to the invention, the radius of the inner contour varies about the rotational axis according to the function: r=r.sub.0+a.Math.sin(n.Math.φ), where r.sub.0=(r.sub.max+r.sub.min)/2, a =(r.sub.max−r.sub.min)/2, and φ=phase angle of the radius (r) between (r.sub.min) and (r.sub.max) in the direction of rotation of the rotor .

Claims

1. A vane pump comprising: a pump housing including a cam ring; a rotor mounted in the cam ring so that it can rotate about a rotational axis; the cam ring including an inner contour with a variable radius that varies between a maximum radius (rmax) and a minimum radius (rmin) in a circumferential direction about the rotational axis; a radial gap formed between the inner contour and the rotor; a number (n) of lift sections each formed from a gap between the cam ring and the rotor, the lift sections constructed with pump chambers in the lift sections; and a plurality of vane elements are mounted on the rotor that slide against the inner contour of the cam ring and limit the pump chambers in the peripheral direction, wherein the variable radius (r) of the inner contour varies about the rotational axis according to the function:
r=r0+a.Math.sin(n.Math.φ), where r0=(rmax+rmin)/2, a=(rmax−rmin)/2 and φ=phase angle of the variable radius between (rmin) and (rmax) in the direction of rotation of the rotor.

2. The vane pump according to claim 1, wherein the inner contour for each lift section has a greater radius than a radius that is formed by an inner contour of the cam ring according to an equation of an ellipse about the rotational axis.

3. The vane pump according to claim 1 wherein the inner contour is defined by the variable radius about the rotational axis and this variable radius varies in its magnitude with respect to a mean radius.

4. The vane pump according to claim 3 wherein the variable radius of the inner contour about the rotational axis over an angle φ of 360° for a number (n) of lift sections with n=2 coincides four times with the radius of an elliptical inner contour of the cam ring.

5. The vane pump according to claim 1 wherein the vane pump includes at least two lift sections.

6. The vane pump according to claim 1 wherein the rotor rotates at a rotational speed from 1000 rpm to 10,000 rpm.

7. The vane pump according to claim 1 for use in a brake booster for motor vehicles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference charac-ters indicate the same parts throughout the views.

(2) FIG. 1 is a cross-sectional view through a vane pump with a pump housing and with a cam ring in which a rotor rotates and on which vane elements are mounted.

(3) FIG. 2 is a section A, as shown in FIG. 1.

(4) FIG. 3 is a profile of an inner contour according to the present invention in comparison with the profile of an inner contour, when this is constructed like an ellipse, wherein, with n=2, two lift sections are formed.

(5) FIG. 4 is a profile of an inner contour according to the present invention in comparison with the profile of an inner contour, when this is constructed like an ellipse, wherein, with n=3, three lift sections are formed.

DETAILED DESCRIPTION OF THE DRAWINGS

(6) FIG. 1 shows a cross-sectional view of a vane pump 1 with a pump housing 10. A cam ring 11 that is equipped with an inner contour 14 is mounted in the pump housing 10. A rotor 12 is mounted so that it can rotate about a rotational axis 13 within the cam ring 11. On the rotor 12 there are vane elements 16 that slide, with their outer sides, against the inner contour 14 when the rotor 12 is set into rotation about the rotational axis 13. The inner contour 14 is constructed such that two lift sections 15 are constructed with pump chambers 15′ in these sections, wherein the lift sections 15 are diametrically opposite each other and the pump chambers 15′ form so-called vane cells. The pump chambers 15′ are limited by the vane elements 16, so that several pump chambers 15′ are formed from the volume of one lift section 15. In the first lift section 15, a suction opening 17 opens and in the opposing second lift section 15, a pressure opening 18 opens, wherein the suction opening 17 is in fluid connection with a suction connection 19. For driving the rotor 12, an electric motor is used that is arranged in a way that is not shown in more detail in or on the pump housing 10 and can be operated by means of an electrical connection 20 with electrical energy.

(7) The inner contour 14 varies between a minimum radius r.sub.min and a maximum radius r.sub.max, wherein, as an example, r.sub.max is reached at a 12-o'clock position, and wherein r.sub.min is reached at a 3-o'-clock position, so that the angle between the maximum radius r.sub.max and the minimum radius r.sub.min is 90° (0<φ<<π/2).

(8) FIG. 2 shows the section A, as shown in FIG. 1, and the inner contour 14 of the cam ring 11 is shown over a segment of approximately 90°. The radius r is shown here with a minimum radius r.sub.min at 0° and a maximum radius r.sub.max at 90°. Shown is an inner contour 14 that is defined with the function r=r.sub.0+a.Math.sin(n.Math.φ) according to the present invention; furthermore, an inner contour 21 according to an equation of an ellipse is shown for comparison. Here it can be seen that the radius of the inner contour 14 is greater with respect to the rotor axis 13 than an inner contour 21 that is constructed according to an equation of an ellipse. If the rotor 12 rotates about the rotational axis 13, then the outer edges of the vane elements 16 slide on the inner contour 14. Due to the farther projecting inner contour 14 that also generates an increase of the lift sections 15 with the pump chambers 15′ with respect to the inner contour 21 according to an equation of an ellipse, the vane elements 16 move, beginning at r.sub.min and with a rotation of the rotor 12 in the counterclockwise direction, out from their receptacle pockets 22 from the rotor 12, so that for the lifting movement of the vane elements 16, a harmonic movement is produced and the contact line between the outer sides of the vane elements 16 and the inner contour 14 wanders periodically back and forth over the crest of the vane elements 16 on the outer side, which produces reduced wear.

(9) The inner contour 14 is more projecting than the inner contour 21, with respect to the rotational axis 13, according to an equation of an ellipse, and the vane elements 16 are pressed radially inward by a movement of the vane elements 16 in the position r.sub.min up to the position r.sub.max against the centrifugal force that presses the vane elements 16 against the inner contour 14, wherein reduced wear is also realized in the further angular profile.

(10) FIG. 3 shows an inner contour 14 for a number of lift sections 15 in comparison with an inner contour 21 according to an equation of an ellipse with n=2; FIG. 4 shows an inner contour 14 also in comparison with an inner contour 21 according to an equation of an ellipse with a number of lift sections 15 with n=3.

(11) The invention is not limited in its design to the preferred embodiment specified above. On the contrary, a number of variants are conceivable that use the solution shown above, even for designs that are fundamentally different. All of the features and/or advantages emerging from the claims, the description, or the drawings, including structural details or spatial arrangements, can be considered essential to the invention both in themselves and also in different combinations.

LIST OF REFERENCE SYMBOLS

(12) 1 Vane pump 10 Pump housing 11 Cam ring 12 Rotor 13 Rotational axis 14 Inner contour 15 Lift section 15′ Pump chamber 16 Vane element 17 Suction opening 18 Pressure opening 19 Suction connection 20 Electrical connection 21 Inner contour according to an equation of an ellipse 22 Receptacle pocket n Number of lift sections r.sub.min Minimum radius r.sub.max Maximum radius