Automotive liquid pendulum vane pump

The invention refers to an automotive liquid pendulum vane pump for providing pressurized liquid, preferably for the lubrication of an automotive traction engine with pressurized lubrication liquid. More preferably, the invention refers to a mechanical pendulum pump which is not driven electrically but is mechanically driven by the automotive traction engine, and is preferably provided as a variable pendulum pump of which the volumetric performance is variable and independent of the pump's rotational speed.

Compared to a conventional vane pump with rotor vanes which simply slide along a circumferential wall, a pendulum pump has much less wear at the vanes and has a higher hydraulic quality because the pump chambers separated by the pendulum vanes are fluidically very tight. The mechanical concept of a pendulum pump is relatively complex because a rotatable rotor hub as well as a rotatable rotor ring is provided, and the pendulum vanes radially connecting the rotor ring and the rotor hub provide a pendulum oscillation at their rotational path.

If a complex transmission gear between the rotor hub and the eccentric rotor ring should be avoided, the rotor hub drives the rotor ring or the rotor ring drives the rotor hub via the pendulum vanes. DE 10 2012 219 847 Al and EP 2642 073 A2 both disclose typical automotive lubricant pendulum pumps. DE 10 2012 219 847 Al discloses a variable pendulum pump with a shiftable control ring for shifting the rotor ring between a maximum eccentricity and a minimum eccentricity position. The rotational force is transferred from the rotor hub or the rotor ring to the pendulum vane. In the maximum eccentricity position of the control ring supporting the rotor ring, the pump performance is maximized so that a maximum rotational force is transferred between the rotor hub and the rotor ring and in particular between the driven rotor part and the pendulum vanes. But the contact sector in which the rotational force is transferred from the rotor hub or the rotor ring to the pendulum vanes can be so small that temporarily no single or only one single pendulum vane is driven with the rotational force. This leads to transfer force peaks which cause relatively high mechanical wear.

It is an object of the invention to provide an automotive liquid pendulum pump with an increased contact sector.

This object is solved with an automotive liquid pendulum pump with the features of claim 1.

The automotive liquid pendulum pump according to the invention is provided with a static pump housing, with a rotatable rotor ring, a rotatable and non-shiftable rotor hub comprising numerous substantially radial vane slots and with numerous pendulum vanes mechanically connecting the rotor ring and the rotor hub. The rotatable rotor ring can be provided shiftable or non-shiftable. If the rotatable rotor ring is provided non-shiftable, the rotatable rotor ring is always at a position of maximum eccentricity. If the rotatable rotor ring is provided shiftable, the rotatable rotor ring can be shifted and positioned between a maximum eccentricity position and a minimum eccentricity position. The pendulum vanes separate the rotating pump chambers from each other and transmit a rotational force between the rotor hub and the rotor ring. The vane slots at the rotor hub are not necessarily provided with an exactly radial orientation but the slot orientation necessarily has a large radial component.

The pendulum pump is gear-free so that no rotational force is transferred between the rotor hub and the rotor ring and by an external gear. The rotational force is only transferred by the pendulum vanes from the driven rotor hub to the rotor ring. Every pendulum vane comprises a circular pendulum head defining a pendulum hinge together with a corresponding circular undercut recess at the rotor ring. The pendulum vane is hinged non-shiftably but pivotably at the rotor ring. The pendulum hinge is provided at the radially outer end of the pendulum vane.

A circular pendulum foot is provided at the radial inner end of the pendulum vane. The pendulum foot is arranged radially shiftable and also pivotable in the corresponding linear vane slot. The vane slot is substantially a linear vane slot with parallel and plane slot walls. The circular pendulum foot is not a closed circle but is provided with circular and cylindrical portions which ensure that the pendulum foot is always guided and supported in the vane slot in a substantially fluid-tight manner. The circular portions always define a sliding contact-line with the corresponding vane slot wall. The other portions of the pendulum foot are not necessarily circular.

The pendulum head and the pendulum foot are connected by a vane leg. The pendulum vane is preferably provided as one single piece.

The vane slot is provided with a contact slot wall which is substantially plane. A tangential contact nose is provided in the opening region of the vane slot for transferring the rotational force between the pendulum vane and the rotor hub. If the rotor hub is driving the rotor ring, the contact nose is provided at the lagging side of the opening edge of the vane slot. If the rotor ring is driving the rotor hub, the contact nose is provided at the advancing side of the opening edge of the vane slot.

The contact nose is provided as an axial profile extending over the axial length of the vane slot. The axial direction of the pendulum pump is the direction of the rotational axis of the rotor hub.

The pendulum vane is provided with a contact path defined by a contact path surface being in contact with the contact nose within the pump contact sector. At maximum eccentricity, the contact path surface is in force-transferring contact with the contact nose only in the pump contact sector, whereas the contact path surface is not in contact with the contact nose outside the pump contact sector. The larger the pump contact sector is, the more average numbers of pairs of the contact path surface and the contact nose transfer the rotational force between the rotor hub and the pendulum vanes.

The radial inner end of the contact path surface defines a tangential projection which tangentially projects from the body of the pendulum vane leg. The radial extent of the contact path is relatively long and is, preferably, somehow bowed so that the contact path preferably defines a concave surface. The longer the radial extent of the contact path is, the more protrudes the radially inner tangential projection from the vane leg in tangential/circumferential direction.

The cooperating contact slot wall opposite the contact path is completely plane in the region where the pendulum foot is moving and can be in contact, but is provided with a diving recess at the radially outer end section of the vane slot. The diving recess is provided radially inwardly of and preferably adjacent to the contact nose.

The tangential pendulum projection temporarily dives into the diving recess so that a mechanical contact between the radially inner tangential projection of the pendulum vane and the contact slot wall is always avoided, independent of the rotational position and the eccentricity. The diving recess allows to substantially increase the radial extent of the contact path so that the contact sector is substantially increased, as well . As a consequence, the average mechanical force transfer load of every pendulum vane is decreased accordingly so that the pump's reliability and lifetime is increased, and/or a higher total rotational force can be transferred between the rotor hub and the pendulum vanes.

The contact sector is the rotational sector where the contact path surface is in force-transmitting contact with the contact nose.

According to a preferred embodiment of the invention, the rotor hub or the rotor ring is mechanically driven. The pendulum pump is not driven by a separate electric motor but is mechanically driven by an engine which can be the traction engine of the automotive device. Since the pendulum pump is mechanically driven by the traction engine, the rotational speed of the pendulum pump varies within a wide range of, for example, 500 to 5000 rpm. As a result, the rotational speed of the pendulum pump does not correspond with the required hydraulic performance of the pendulum pump.

Therefore, the pendulum pump is provided with a shiftable and non- rotatable control ring which is shiftable with respect to the pump housing between the minimum eccentricity position and a maximum eccentricity position. The eccentricity is the distance of the rotation axis of the rotor hub and of the rotor ring. The rotor ring is rotatably and co-shiftably supported by the control ring. The shifting path can be linear or can be circular. The volumetric capacity of the pump can be adapted by shifting of the control ring into a suitable position thereby defining a suitable volumetric performance. The geometric restrictions in a variable pendulum pump are severe, so that it is difficult to realize a large contact sector. The relatively long contact path, seen in radial direction, provides a relatively smooth transfer of the rotational force between the rotor hub and the pendulum vanes.

Preferably, the inner tangential projection of the pendulum vane dives into the corresponding diving recess at least at the maximum eccentricity position of the shiftable control ring because the maximum eccentricity constitution is the most critical situation with respect to the high rotational force to be transferred. More preferably, the tangential projection dives into the recess at any eccentricity position.

According to a preferred embodiment, the radial extent of the contact path is so large that the contact sector is at least 1,1 times of the chamber sector defined by the angle between two neighbored pendulum vanes or between neighbored vane slots. As a consequence, always at least one pendulum vane transfers the rotational force between the rotor hub and the rotor ring at every eccentricity and in particular at maximum eccentricity. As a result, the rotational force is continuously transferred so that high transfer force peaks at the vanes are avoided.

Preferably, the radially outer end of the contact path surface defines an outer tangential projection. The rotor ring is provided with radial recesses adjacent to the corresponding circular undercut recesses so that the outer tangential vane projection temporarily dives into the corresponding radial recess. The outer tangential projection allows to maximally extend the radial extent of the contact path so that the contact sector can be maximized.

According to a preferred embodiment of the invention, the tangential depth of the tangential diving recess at the contact slot wall is at least 0,1 mm referring to the general plane of the contact slot wall.

Preferably, the rotor hub is driving the rotor ring. The rotor hub is mechanically or electrically driven by an external device.

One embodiment of the invention is described with reference to the enclosed drawings, wherein

figure 1 shows a top view of an opened automotive liquid pendulum pump according to the invention,

figure 2 shows an enlarged view of figure 1, showing a pendulum vane in the contact sector CO, and

figure 3 shows an enlarged view of figure 1, showing a pendulum vane right before rotating into the contact sector CO.

Figure 1 shows an open, namely without a cover lid, automotive liquid pendulum pump 10 which is provided to be mechanically driven. The pump 10 is a so-called variable pendulum pump of which the volumetric performance can be controlled independent of the rotational speed.

The pendulum pump 10 can be mechanically connected to and driven by a traction engine, for example by an internal combustion engine. The pendulum pump 10 provides pressurized lubricant liquid, for example for the lubrication of the traction engine and/or for providing an actuation force to a hydraulic device.

The pendulum pump 10 is provided with a metal pump housing 12 housing a shiftable and non-rotatable control ring 18, a rotatable and shiftable rotor ring 16 and a rotatable and non-shiftable rotor hub 14. The control ring 18 is provided pivotable around a pivot element 20 so that the shifting path of the control ring 18 is not exactly linear are but is circular. The shifting position of the control ring 18 is defined by two counteracting hydraulic control chambers 22, 24 and a preload spring 26.

The control ring 18 supports the rotatable rotor ring 16 so that the control ring 18 defines the shifting position of the rotor ring 16 and thereby defines the eccentricity of the rotor ring 16 with respect to the rotor hub 14. The rotor ring 16 thereby can be shifted and positioned between a maximum eccentricity position, as shown in figure 1, and a minimum eccentricity position in which the eccentricity can be close to zero or even zero so that only a minimum volumetric performance or no volumetric performance at all can be realized.

The pendulum pump 10 is provided with seven pendulum vanes 30 mechanically connecting the rotor ring 16 and the rotor hub 14. The rotor hub 14 is mechanically driven by an external power device, for example by an internal combustion engine, and directly drives the pendulum vanes 30 and indirectly drives the rotor ring 16. The rotor hub 14 has a generally cylindrical surface 15 and comprises seven radial vane slots 50 for guiding the vanes 30. The vane slots 50 define slot openings at the cylindrical surface 15.

The pendulum vanes 30 have two functions, namely to separate the rotating pump chambers from each other and to transfer the rotational force from the rotor hub 14 to the rotor ring 16 to co-rotate the rotor ring 16 with the rotor hub 14.

Each pendulum vane 30 comprises at the radial outer end a circular pendulum head 32 which is pivotably supported in a corresponding circular undercut recess 70 at the rotor ring 16. The circular pendulum head 32 and the circular undercut recess 70 together define a pendulum hinge 33 so that the pendulum vane 30 can oscillate with respect to the rotor ring 16.

The pendulum vanes 30 comprise a circular pendulum foot 34 at the radially inner end thereof. The pendulum foot 34 is not completely circular but is provided with two circular sections 341, 342 which are provided with a constant foot radius r with reference to the pendulum foot center. The pendulum foot 34 is provided pivotable as well as radially shiftable in the corresponding vane slot 50 in an approximately fluid-tight manner.

The vane slot 50 is defined by four radial slot walls which are provided parallel with the radial slot center axis and are defined by the rotating rotor hub 14 and the static housing side walls. The vane slots 50 have a tangential slot width w between the lagging vane slot wall 54 and the parallel advancing vane slot wall 52 defined by the rotor hub 14. The slot width w is approximately two times the foot radius r of the vane foot 34: w= 2 x r.

The lagging vane slot wall defines a contact slot wall 54 and is provided with a tangential contact nose 58 in the opening region of the vane slot 50. The tangential contact nose 58 has a constant cross-section over its entire axial extent and has a radius of at least a few millimeters. The contact nose 58 is not a sharp edge.

The pendulum vane 30 is provided with a contact path 36 defined by a concave contact path surface 36' which is provided at the lagging side of the vane 30 and is in contact with the corresponding contact nose 58 when the corresponding vane 30 and slot 50 is rotatory within a contact sector CO. The contact sector CO is the rotational sector where the contact path surface 36' is in mechanical and force-transmitting contact with the corresponding contact nose 58 to transfer the rotational force from the rotor hub 14 to the pendulum vane 30 and via the vane 30 to the rotor ring 16.

In the present embodiment, the contact sector CO is 1,5 times larger than the chamber angle CH defined by the angle enclosed by two neighbored vane slots 50 or two neighbored pendulum vanes 30. This means that, at a maximum eccentricity position as shown in figure 1, the average number of pendulum vanes 30 transferring the rotational force from the rotor hub 14 to the rotor ring 16 is about 1,5 at maximum eccentricity position. At other eccentricity positions, the contact sector is smaller than in the maximum eccentricity position.

The radial inner end of the contact path surface 36' defines an inner tangential projection 40 tangentially protruding from the vane leg 35 connecting the pendulum head 32 and the pendulum foot 34. The pendulum vane 30 is defined by one single vane body 31.

The generally plane contact slot wall 54 is provided with a concave diving recess 56 radially inwardly adjacent to the contact nose 58. The diving recess 56 has a tangential depth d of more than 0,5 mm referring to the general plane of the contact slot wall 54. In the maximum eccentricity position as shown in figure 1 and during the contact phase within the contact sector CO, the inner tangential pendulum projection 40 dives into the diving recess 56 without getting into contact with the surface of the diving recess 56.

The radial outer end of the contact path surface 36' defines an outer tangential projection 38 tangentially projecting from the vane leg 35. The outer tangential projection 38 is provided radially inwardly adjacent to the circular pendulum head 32. The rotor ring 16 is provided with radial recesses 72 tangentially adjacent to the circular undercut recesses 70. The radial recesses 72 and the undercut recesses 70 are provided at the inner circumferential surface 74 of the rotor ring 16. The outer tangential projection 38 temporarily dives into the corresponding radial the recess 72 during the rotor rotation, but preferably not in the contact sector CO.