DE112020007530T5 - Variable displacement lubrication pump - Google Patents

Abstract

The invention relates to a lubricant pump (10) with variable displacement, which is designed to provide pressurized lubricant, with a fixed pump housing (16), a rotatable pump rotor (24), a displaceable control ring (20), which is designed between a Position of maximum eccentricity and a position of minimum eccentricity to be displaceable, a suction chamber (30), an outlet chamber (32), a pilot control chamber (40), which is designed such that the control ring (20) is moved by a pilot chamber hydraulic pressure in the direction of the position of minimum eccentricity is acted upon, a pilot control chamber loading channel (48), which is set up to fluidly connect the pilot control chamber (40) to the outlet chamber (32), a pilot control chamber emptying channel (50), which is set up to fluidically connect the pilot control chamber (40) to the suction chamber (30). to connect, and a passive internal valve arrangement (62) which is formed by the pump housing (16) and by the control ring (20), the internal valve arrangement (62) being mechanically regulated and set up by the control ring (20). To control an admission lubricant flow (LF) through the pilot chamber admission channel (48) and an emptying lubricant flow (DF) through the pilot chamber emptying channel (50) based on a displacement position of the control ring (20). Due to the passive internal valve arrangement (62), the lubricant pump (10) according to the invention can with Variable displacement can be made compact and cost-effective.

Description

The present invention relates to a variable displacement lubricant pump for supplying lubricant under pressure, more particularly to a mechanically driven variable displacement lubricant pump for supplying lubricant under pressure to an internal combustion engine.

The lubricant pump is mechanically driven by the engine, such as through a gear or belt, and is fluidly coupled to the engine to pump the pressurized lubricant to and through the engine. The variable displacement of the lubricant pump enables a pump outlet pressure of the lubricant pump to be controlled and/or stabilized, and thereby, for example, a lubricant gallery pressure in the engine can be controlled and/or stabilized.

Variable displacement lubricant pumps are used, for example, in WO 2018/068841 A1 and US 9,670,925 B2 described. The variable displacement lubricant pumps described include a stationary pump housing and a rotatable pump rotor having a plurality of rotor blades configured to rotate within a slidable control ring, the control ring being configured to be slidable in a direction of displacement between a position of maximum eccentricity and a position of minimum eccentricity to be. The described variable displacement lubricant pumps further include a suction chamber configured to be filled with unpressurized lubricant during pumping operation, a discharge chamber configured to be filled with pressurized lubricant during pumping operation, and a pilot chamber , which is arranged to be acted upon during the pumping operation with a pilot chamber hydraulic pressure, and which is configured such that the control ring is acted upon by the pilot chamber hydraulic pressure toward the position of minimum eccentricity. The described variable displacement lubricant pumps further include a pilot chamber apply line configured to fluidly connect the pilot chamber to a high pressure and a pilot chamber exhaust line configured to fluidly connect the pilot chamber to a low pressure.

The variable displacement lubricant pumps described all have a separate external hydraulically and/or electrically controlled valve arrangement for controlling a load lubricant flow through the pilot chamber load line and/or a drain lubricant flow through the pilot chamber drain line as needed to control the pilot chamber hydraulic pressure during pumping operation. However, the components of the separate external valve assembly require additional space and add cost.

It is therefore an object of the present invention to provide a compact and inexpensive variable displacement lubricant pump.

This object is achieved with a variable displacement lubricant pump having the features of claim 1.

The variable displacement lubricant pump of the present invention includes a stationary pump housing defining a pump inlet and a pump outlet. The pump housing typically includes a housing main body defining a plurality of pump chambers and a separate housing cover attached (fluid-tight) to the housing main body. The pump inlet is typically fluidly connected to a lubricant reservoir, and the pump outlet is typically fluidly connected to an engine for supplying pressurized lubricant to the engine.

The variable displacement lubricant pump of the present invention further includes a rotatable pump rotor disposed within the pump housing, specifically within a pumping chamber defined by the pump housing and a slidable control ring. The pump rotor is configured to rotate about a fixed axis of rotation. The pump rotor includes a plurality of rotor blades defining a plurality of pumping chamber compartments therebetween. The rotor blades and thus the pumping chamber compartments are arranged to rotate within the pumping chamber of the control ring to thereby pump lubricant from the pump inlet to the pump outlet. The pump rotor is driven mechanically by the engine, for example via a belt drive or a gearbox.

The variable displacement lubricant pump of the present invention further includes a slidable control ring disposed within the pump housing and defining the pumping chamber, typically substantially cylindrical, in which the pump rotor is disposed. The control ring is arranged to be displaceable relative to the axis of rotation of the pump rotor in a displacement direction to change an eccentricity of the pumping chamber center relative to the axis of rotation of the pump rotor and thereby a nominal fluid displacement and thus a volumetric one To change pumping capacity of the pump rotor. Specifically, the control ring is translatable between a maximum eccentricity position with maximum volumetric pumping power and a minimum eccentricity position with minimum volumetric pumping power. The control ring can be designed to be exactly linearly displaceable or pivotable with a substantially arcuate direction of displacement. The control ring is typically biased to the position of maximum eccentricity by a bias spring.

The variable displacement lubricant pump of the present invention further includes a suction chamber and a discharge chamber both defined by the pump housing and the control ring. The suction chamber and discharge chamber are typically located radially outward of the pumping chamber on opposite lateral sides of the control ring. The suction chamber is fluidly connected to the pump inlet and configured to be filled with unpressurized lubricant during pumping operation. The suction chamber is typically filled with lubricant at substantially atmospheric pressure drawn from the lubricant reservoir. The outlet chamber is fluidly connected to the pump outlet and configured to be filled with pressurized lubricant during pumping operation.

The variable displacement lubricant pump of the present invention further includes a pilot chamber defined by the pump housing and the control ring. The pilot chamber is set up to be subjected to a pilot chamber hydraulic pressure during pumping operation. The pilot chamber is located radially outside of the pumping chamber and is formed such that the pilot ring is urged toward the minimum eccentricity position by the pilot chamber hydraulic pressure. The current shifting position of the control ring and thus the current volumetric pump performance of the pump rotor is consequently defined by the current pilot chamber hydraulic pressure. The pilot chamber hydraulic pressure is directly or indirectly hydraulically coupled to the pump outlet pressure, allowing the variable displacement lubricant pump to deliver a relatively constant desired pump outlet pressure regardless of the actual speed of the pump rotor. The basic principle of operation of a variable displacement lubricant pump having a slidable control ring and a pilot chamber as described above is well known and will therefore not be described in detail.

The variable displacement lubricant pump of the present invention further includes a pilot chamber apply passage and a pilot chamber exhaust passage. The pilot chamber pressurizing passage is configured to fluidly connect the pilot chamber to the outlet chamber, and the pilot chamber purge passage is configured to fluidly connect the pilot chamber to the suction chamber. The pilot chamber application passage and the pilot chamber exhaust passage are preferably provided internally, the pilot chamber application passage and the pilot chamber exhaust passage being typically formed by the pump housing and/or by the control ring.

According to the invention, the variable displacement lubricant pump has a passive internal valve assembly formed by the pump housing and the control ring and configured to control both the apply lubricant flow through the pilot chamber apply passage and the exhaust lubricant flow through the pilot chamber exhaust passage. The passive internal valving of the present invention is directly regulated mechanically by the slidable control ring so that the apply lubricant flow and the exhaust lubricant flow are inherently controlled based on the actual sliding position of the control ring without the need for any separate active valve control means.

The self-adjusting passive internal valve assembly of the present invention is formed entirely within the pump housing and provides reliable control ring position based control of pilot chamber hydraulic pressure during pumping operation without the need for any separate external control valves or valve control means. This provides a compact and inexpensive variable displacement lubricant pump.

In a preferred embodiment of the present invention, the internal valve assembly includes a bleed valve mechanism for controlling the bleed lubricant flow, a movable flow controlling part of the bleed valve mechanism being formed by the control ring. The purge valve mechanism is therefore regulated directly (mechanically) by the control ring without the need for any separate flow regulation or actuating elements. This provides reliable control ring position based control of purge lubricant flow and hence a reliable yet compact and cost effective variable displacement lubricant pump.

In a particularly preferred embodiment of the present invention, the drain valve mechanism is defined by a fixed pump housing-side closing shoulder formed on the pump housing and by a corresponding movable control ring-side closing shoulder formed on the control ring. The moveable closing shoulder on the control ring side forms the moveable part of the evacuation valve mechanism that controls the evacuation flow. When the control ring is displaced, the closing shoulder on the control ring side is always shifted relative to the fixed closing shoulder on the pump housing side. The two corresponding closure shoulders are configured to touch when the control ring is positioned between the maximum eccentricity position and a scavenge port opening position and not to touch when the control ring is positioned between the scavenge port opening position and the minimum eccentricity position. The two closing shoulders partially define the pilot chamber bleed passage, so the bleed lubricant flow must pass between the two closing shoulders. The pilot chamber bleed passage is therefore fluidly closed when the two closing shoulders are in contact and fluidly open when the two closing shoulders are not in contact. The distance between the position of maximum eccentricity and the discharge duct opening position and thus the position at which the discharge duct is opened/closed during a control ring movement can be easily and precisely defined by a displacement direction expansion of the contact surface between the two closing shoulders in the position of maximum eccentricity of the control ring become. The two corresponding closing shoulders provide a simple and reliable internal bleed valve mechanism.

Preferably, the internal valve assembly includes an application valve mechanism for controlling the application lubricant flow, a movable flow controlling part of the application valve mechanism being formed by the control ring. The apply valve mechanism is therefore regulated directly (mechanically) by the control ring without the need for separate flow regulation or actuators. This provides reliable control ring position based control of the apply lubricant flow and hence a reliable yet compact and inexpensive variable displacement lubricant pump.

The application valve mechanism is particularly preferably formed by an application groove on the pump housing side formed on a sliding surface of the pump housing and by a corresponding application groove on the control ring side formed on a sliding surface of the control ring, the two sliding surfaces being in frictional contact with one another. The pressure groove on the control ring side is movable relative to the fixed pressure groove on the pump housing side and thus forms the movable part of the pressure valve mechanism that controls the pressure flow. When the control ring is displaced, the pressure groove on the control ring side is always shifted relative to the fixed pressure groove on the pump housing side. The two corresponding biasing grooves are formed such that they overlap when the control ring is positioned between the maximum eccentricity position and a biasing channel closed position to form a lubricant passage allowing lubricant flow between the two biasing grooves. The two corresponding biasing grooves are also formed such that they do not overlap when the control ring is positioned between the biasing port closed position and the minimum eccentricity position to prevent lubricant flow between the biasing grooves. The two corresponding Beaufschlagungsnuten delimit - at least partially - the Vorsteuerkammerbeaufschlagungskanal so that the Aufschlagungslubricant flow through the pilot chamber Beaufschlagungskanal over the flow cross section of the lubricant passage formed by the overlapping Beaufschlagungsnuten is controlled. The pilot chamber application channel is fluidically closed if the two application grooves do not overlap. The distance between the position of maximum eccentricity and the loading channel closing position and thus the position at which the loading channel is opened/closed during a control ring movement can be easily and precisely determined by expanding the lubricant passage in the direction of displacement in the position of maximum eccentricity of the control ring. The two corresponding loading grooves provide a simple and reliable internal loading valve mechanism.

In a preferred embodiment of the present invention, the exhaust port open position and the pressurizing port closed position are substantially the same such that the pilot chamber pressurizing port is closed at substantially the same time as the pilot chamber exhaust port is opened and vice versa. The pilot chamber admission channel and the pilot chamber Mere drainage ducts are consequently not open at the same time, at least not for a significant duration. This prevents or at least minimizes undesirable lubricant leakage flow from the high pressure side discharge chamber to the low pressure side suction chamber via the pilot chamber during pumping operation, thus providing a reliable variable displacement lubricant pump.

Typically, the total displacement of the control ring is relatively small, which only allows a relatively small overlap between the two corresponding loading grooves in the direction of displacement. The pressure groove on the pump housing side therefore preferably extends essentially transversely to the displacement direction, and the pressure groove on the control ring side preferably comprises a passage section which extends essentially parallel to the pressure groove on the pump housing side. This makes it possible to provide the two corresponding loading grooves with a relatively large overlap in the transverse direction and thus to provide the lubricant passage formed by the overlapping of the two corresponding loading grooves with a relatively large flow cross section. The relatively large flow cross-section ensures reliable fluidic communication between the pilot chamber and the outlet chamber when the pilot chamber admission channel is open. This creates a reliable variable displacement lubricant pump.

Internal combustion engines typically require different lubricant pressures for different engine speeds. In a preferred embodiment of the present invention, there is therefore a separate auxiliary pilot chamber which is set up so that an auxiliary pilot chamber hydraulic pressure is applied during pump operation and at times it is fluidically connected to a high pressure via an auxiliary pilot chamber pressurization line, the auxiliary pilot chamber being designed in such a way that the control ring is applied by the auxiliary pilot chamber hydraulic pressure toward the minimum eccentricity position. The auxiliary pilot chamber is typically configured to be fluidly connected to the outlet chamber or to an engine lubricant gallery either directly or indirectly, for example via an auxiliary pilot chamber control valve. The separate auxiliary pilot chamber allows the variable displacement lubricant pump to be designed for two different pump outlet set pressure levels. This creates a versatile variable displacement lubricant pump.

• 1 eine Draufsicht auf eine offene (ohne Gehäusedeckel) erfindungsgemäße Schmiermittelpumpe mit variabler Verdrängung zeigt, und
• 2 eine Querschnittsansicht eines gekennzeichneten Pumpenbereichs der Schmiermittelpumpe aus 1 zeigt,
• 3 eine vergrößerte Ansicht des gekennzeichneten Pumpenbereichs der Schmiermittelpumpe mit variabler Verdrängung aus 1 zeigt, wobei ein Steuerring in einer Position maximaler Exzentrizität positioniert ist,
• 4 den Pumpenbereich aus 2 zeigt, wobei jedoch der Steuerring in einer Beaufschlagungskanalschließposition positioniert ist,
• 5 den Bereich aus 2 zeigt, wobei jedoch der Steuerring in einer Position minimaler Exzentrizität positioniert ist, und
• 6 einen idealisierten, vereinfachten Verlauf eines Pumpenauslassdrucks als Funktion einer Pumpenrotordrehzahl für die Schmiermittelpumpe mit variabler Verdrängung aus 1 zeigt.

An embodiment of the present invention will be described with reference to the accompanying drawings, wherein

• 1 Figure 13 shows a plan view of an open (without casing cover) variable displacement lubricant pump according to the invention, and
• 2 Figure 12 shows a cross-sectional view of a designated pump area of the lubricant pump 1 shows,
• 3 Figure 12 shows an enlarged view of the labeled pump area of the variable displacement lubricant pump 1 shows with a control ring positioned in a position of maximum eccentricity,
• 4 the pump area 2 but with the control ring positioned in an application channel closed position,
• 5 the area 2 but with the control ring positioned in a position of minimum eccentricity, and
• 6 proposes an idealized, simplified curve of pump outlet pressure as a function of pump rotor speed for the variable displacement lubricant pump 1 shows.

1 FIG. 1 shows a variable displacement lubricant pump 10 configured to draw unpressurized lubricant from a lubricant reservoir 12 and provide pressurized lubricant to an internal combustion engine 14. FIG.

The lubricant pump 10 includes a fixed pump housing 16 having a housing main body 18 and a housing cover 19 fixed to the housing main body 18 .

The lubricant pump 10 comprises a displaceable control ring 20 which is arranged in the pump housing 16 and which radially delimits a substantially cylindrical pump chamber 22, and a rotatable pump rotor 24 which is arranged in the pump chamber 22 so as to be rotatable about a fixed rotor axis of rotation R. The control ring 20 is set up to be displaceable in a displacement direction S between a position of maximum eccentricity and a position of minimum eccentricity in order to change an eccentricity of a pumping chamber center with respect to the axis of rotation R of the rotor.

The pump rotor 24 includes a plurality of radially displaceable rotor blades 26, wherein the pump rotor 24 is set up such that the rotor blades 26 against a radial inside of the Pump chamber 22 are pressed when the pump rotor 24 rotates. The rotor blades 26 define a plurality of fluidly separated pumping chamber compartments 28 therebetween.

The lubricant pump 10 includes a suction chamber 30 and a discharge chamber 32 located on different lateral sides of the control ring 20 and bounded by the control ring 20 and the pump housing 16 . The suction chamber 30 is fluidly connected to the lubricant reservoir 12 and is configured to be filled with unpressurized lubricant (typically at substantially atmospheric pressure) drawn from the lubricant reservoir 12 during pumping operation. The outlet chamber 32 is fluidly connected to the engine 14 and configured to be filled with pressurized lubricants during pumping operation. Specifically, the discharge chamber 32 is filled with lubricant having a pump discharge pressure PD.

The lubricant pump includes a pre-load spring 34 disposed in a spring chamber 36 . The spring chamber 36 is located on a first face of the control ring 20 and the pre-load spring 34 is configured to pre-load the control ring 20 toward the position of maximum eccentricity. The spring chamber 36 is directly fluidly connected to the suction chamber 30 via an internal spring chamber fluid passage 38 .

The lubricant pump 10 includes a pilot chamber 40 and a separate auxiliary pilot chamber 42. Both pilot chambers 40, 42 are arranged on a second end face of the control ring 20, which is the first end face of the control ring 20 opposite. The pilot chamber 40 is configured to be supplied with a pilot chamber hydraulic pressure during the pumping operation, and the auxiliary pilot chamber 42 is configured to be supplied with an auxiliary pilot chamber hydraulic pressure during the pumping operation. The pilot chamber 40 is formed such that the control ring 20 is urged toward the minimum eccentricity position by the pilot chamber hydraulic pressure, and the auxiliary pilot chamber 42 is formed such that the control ring 20 is urged toward the minimum eccentricity position by the auxiliary pilot chamber hydraulic pressure.

The auxiliary pilot chamber 42 is fluidically connected to an external auxiliary pilot chamber control valve 44 via an auxiliary pilot chamber pressurizing line 46 . The auxiliary pilot chamber control valve 44 is configured to be hydraulically regulated by the pump discharge pressure PD. Specifically, the auxiliary pilot chamber control valve 44 is configured to fluidly connect the auxiliary pilot chamber 42 to the lubricant reservoir 12 when the pump outlet pressure PD is less than a predetermined switching threshold, and to fluidly connect the auxiliary pilot chamber 42 to the pump outlet pressure PD when the pump outlet pressure PD is equal to or greater than is the specified switching threshold. The auxiliary pilot chamber 42 is thus set up to be temporarily fluidly connected to a high pressure.

Lubricant pump 10 includes a pilot chamber apply passage 48 and a pilot chamber exhaust passage 50, both of which are formed internally in the present embodiment and both are defined by pump housing 16 and control ring 20.

The pilot chamber application channel 48 is essentially formed by an application groove 52 on the control ring side and by a corresponding application groove 54 on the pump housing side. The loading groove 52 on the control ring side is formed on a control ring sliding surface 56 of the control ring 20 . The pressure groove 54 on the pump housing side is formed on a housing sliding surface 58 of the pump housing 16 , in particular the housing cover 19 , with the housing sliding surface 58 being in frictional contact with the control ring sliding surface 56 . The pressure groove 52 on the control ring side is essentially L-shaped and includes an inflow section 53, which extends essentially parallel to the displacement direction S, and a passage-providing section 55, which extends essentially perpendicular to the displacement direction S. The pressure groove 54 on the pump housing side is essentially rectilinear and extends essentially perpendicular to the direction of displacement S and thus essentially parallel to the passage-providing section 55 of the pressure groove 52 on the control ring side. The pressure groove 52 on the control ring side is directly fluidic with the outlet chamber 32 and the pressure groove 54 on the pump housing side is directly fluidly connected to the pilot chamber 40. The pilot chamber loading channel 48 is thus set up to fluidly connect the pilot chamber 40 to the outlet chamber 32 .

The pilot chamber bleed passage 50 is basically formed by a bleed recess 60 formed in a pump housing portion separating the pilot chamber 40 from the suction chamber 30 . The emptying recess 60 is designed in such a way that the pilot chamber emptying channel 50 is set up to fluidly connect the pilot chamber 40 to the suction chamber 30.

The lubricant pump 10 includes a passive internal valve assembly 62 having an apply valve mechanism 64 configured to control an apply lubricant flow LF through the pilot chamber apply passage 48 and a purge valve mechanism 66 configured to control a purge lubricant flow DF through the pilot chamber purge passage 50.

The pressurizing valve mechanism 64 is formed by the movable pressurizing groove 52 on the control ring side and by the stationary pressurizing groove 54 on the pump housing side, in particular by the passage-providing section 55 of the pressurizing groove 52 on the control ring side and by the pressurizing groove 54 on the pump housing side overlap when the control ring 20 is between the in 3 shown position of maximum eccentricity and an in 4 is positioned in the illustrated biasing channel closed position to form a lubricant passage 68 which allows lubricant to flow between the two biasing grooves 52,54. The two loading grooves 52, 54 are also designed in such a way that they do not overlap when the control ring 20 is between the loading channel closed position and the in 5 shown position of minimal eccentricity is positioned to prevent a flow of lubricant between the two loading grooves 52,54 and thus a flow of lubricant through the pilot chamber loading channel 48. The flow cross section of the lubricant passage 68 regulates the flow of lubricant from the control ring side loading groove 52 into the pump housing side loading groove 54 and thus regulates the current loading lubricant flow LF through the pilot chamber loading channel 48. The flow cross section of the lubricant passage 68 and thus the loading lubricant flow LF are at a maximum when the control ring 20 is in position positioned with maximum eccentricity.

The drain valve mechanism 66 is formed by a movable closing shoulder 70 on the control ring side formed on the control ring 20 and by a corresponding fixed closing shoulder 72 on the pump housing side formed on the pump housing 16 , in particular on the main housing body 18 . The two closing shoulders 70, 72 partially define the pilot chamber bleed passage 50. The two closing shoulders 70, 72 are configured to touch when the control ring 20 is positioned between the position of maximum eccentricity and a bleed passage closed position to fluidly close the pilot chamber bleed passage 50. The two closure shoulders 70, 72 are further configured such that they do not touch when the control ring 20 is positioned between the bleed passage closed position and the position of maximum eccentricity to fluidly open the pilot chamber bleed passage 50. In the present embodiment, the emptying channel closing position corresponds to that in 4 shown impingement channel opening position match. The current drain lubricant flow DF is regulated by a current clearance 74 between the two closing shoulders 70, 72, the clearance 74 and hence the drain lubricant flow DF being at a maximum when the control ring 20 is positioned in the position of minimum eccentricity.

The passive internal valve arrangement 62 is formed entirely by the pump housing 16 and by the control ring 20, with the fixed parts of both valve mechanisms 64,66, i.e. the pump housing-side pressurizing groove 54 and the pump housing-side closing shoulder 72, being formed by the pump housing 16, and the movable Parts of the two valve mechanisms 64, 66, ie the pressure groove 52 on the control ring side and the closing shoulder 70 on the control ring side, are formed by the control ring 20. The passive internal valve assembly 62 is thus regulated mechanically directly by the control ring 20 such that the actual apply lubricant flow LF and the actual deflate lubricant flow DF are both inherently controlled based on the actual shifting position of the control ring 20 .

6 shows an idealized, simplified course of the pump outlet pressure PD as a function of a pump rotor speed RS of the lubricant pump 10.

In a first speed interval I1, the pump outlet pressure PD and thus the pilot chamber hydraulic pressure increases with increasing pump speed RS since the control ring 20 is pushed by the pre-loading spring 34 into the position of maximum eccentricity.

At a first pump rotor speed value RS1, the control annulus bias produced by the pilot chamber hydraulic pressure of the pilot chamber 40 toward the minimum eccentricity position is equal to the control annulus bias produced by the bias spring 34 toward the maximum eccentricity position.

In a second speed interval 12, the pump outlet pressure PD therefore remains essentially constant at a first setpoint pump outlet pressure level PD1, since the control ring 20 is continuously shifted towards the position of minimum eccentricity as the pump rotor speed RS increases, as a result of which the nominal fluid displacement and thus the volumetric pumping power of the pump rotor 24 continuously reduced.

At a second pump speed value RS2 , the control ring 20 reaches the apply port closed/exhaust port open position such that the pilot chamber 40 is fluidically isolated from the discharge chamber 32 and fluidly connected to the suction chamber 30 . Therefore, the pilot chamber hydraulic pressure decreases, so that the control ring 20 is again moved toward the maximum eccentricity position due to the pre-loading of the pre-loading spring 34 . However, this results in the pilot chamber 40 again being fluidly connected to the outlet chamber 32 such that the control ring 20 is again moved towards the position of minimum eccentricity. The control ring 20 is thus “frozen” to a certain extent approximately at the loading channel closed position/emptying channel opening position.

In a third speed interval I3, the pump outlet pressure PD therefore rises again due to the “frozen” and therefore immobile control ring 20 as the pump rotor speed RS increases.

At a third pump rotor speed value RS3, the pump outlet pressure PD reaches the switching threshold of the auxiliary pilot chamber control valve 44, so that the auxiliary pilot chamber 42 is fluidly connected to and thus subjected to the pump outlet pressure PD. This causes additional loading of the control ring towards the position of minimum eccentricity, which is directly proportional to the pump outlet pressure PD.

In a fourth speed interval I4, the pump outlet pressure PD remains essentially constant at a second pump outlet target pressure level PD2, since the control ring 20 is continuously shifted towards the position of minimum eccentricity with increasing pump rotor speed RS, due to the continuously increasing additional control ring loading towards the position of minimum eccentricity, the is caused by the continuously increasing hydraulic pressure of the auxiliary pilot chamber 42.

A similar course of the pump outlet pressure can be realized if the auxiliary pilot chamber 42 is fluidly connected directly to the pump outlet pressure PD without an intermediate auxiliary pilot chamber control valve 44 . The auxiliary pilot chamber 42 may also be configured to communicate with an engine lubricant gallery pressure or any other engine lubricant pressure instead of the pump outlet pressure PD.

Reference List

10

Variable displacement lubrication pump

12

lubricant container

14

combustion engine

16

pump housing

18

case main body

19

housing cover

20

control ring

22

pump chamber

24

pump rotor

26

rotor blades

28

pump chamber compartments

30

suction chamber

32

outlet chamber

34

pre-load spring

36

spring chamber

38

Spring Chamber Fluid Channel

40

pilot chamber

42

auxiliary pilot chamber

44

Auxiliary pilot chamber control valve

46

Auxiliary pilot chamber admission line

48

Pilot Chamber Admission Channel

50

Pilot Chamber Drain Channel

52

pressure groove on the control ring side

53

inflow section

54

pressure groove on the pump housing side

55

passage providing section

56

control ring sliding surface

58

housing sliding surface

60

drainage recess

62

passive internal valve assembly

64

admission valve mechanism

66

drain valve mechanism

68

lubricant passage

DF

drain lubricant flow

I1-I4

pump rotor speed intervals

LF

loading lubricant flow

PD

pump outlet pressure

PD1,PD2

Pump Outlet Target Pressure Levels

R

rotor axis of rotation

RS

pump rotor speed

RS1-RS3

pump rotor speed values

S

shift direction

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2018068841 A1 [0003]
• US 9670925 B2 [0003]

Claims (8)

A variable displacement lubricant pump (10) arranged to provide pressurized lubricant comprising - a stationary pump housing (16), - a rotatable pump rotor (24) with a plurality of rotor blades (26) which are arranged to rotate within a slidable control ring (20), - wherein the displaceable control ring (20) is set up to be displaceable in a displacement direction (S) between a position of maximum eccentricity and a position of minimum eccentricity, - a suction chamber (30) arranged to be filled with non-pressurized lubricant during pumping operation, - an outlet chamber (32) arranged to be filled with pressurized lubricant during pump operation, - a pilot chamber (40) which is set up to be acted upon by a pilot chamber hydraulic pressure during pumping operation and which is designed in such a way that the control ring (20) is acted upon by the pilot chamber hydraulic pressure in the direction of the position of minimum eccentricity, - a pilot chamber loading channel (48) which is set up to fluidly connect the pilot chamber (40) to the outlet chamber (32), - a pilot chamber evacuation channel (50) which is set up to fluidly connect the pilot chamber (40) to the suction chamber (30), and - a passive internal valving (62) formed by the pump housing (16) and by the control ring (20), the internal valving (62) being mechanically regulated by the control ring (20) and being arranged to provide a loading lubricant flow (LF ) through the pilot chamber apply passage (48) and to control a bleed lubricant flow (DF) through the pilot chamber bleed passage (50) based on a shifted position of the control ring (20). Variable displacement lubrication pump (10). claim 1 wherein the internal valve assembly (62) includes a bleed valve mechanism (66) for controlling the bleed lubricant flow (DF), and wherein a moveable part (70) of the bleed valve mechanism (66) is formed by the control ring (20). Variable displacement lubrication pump (10). claim 2 , wherein the drain valve mechanism (66) is formed by a fixed pump housing-side closing shoulder (72) formed on the pump housing (16) and by a corresponding movable control ring-side closing shoulder (70) formed on the control ring (20), the two corresponding closing shoulders (70, 72) are designed in such a way - that they touch when the control ring (20) is positioned between the position of maximum eccentricity and a discharge channel opening position in order to fluidly close the pilot chamber discharge channel (50), and - that they do not touch when the control ring (20 ) is positioned between the exhaust port opening position and the minimum eccentricity position to fluidly open the pilot chamber exhaust port (50). A variable displacement lubricant pump (10) as claimed in any preceding claim, wherein the internal valve assembly (62) includes an apply valve mechanism (64) for controlling the apply lubricant flow (LF), and wherein a movable part (52) of the apply valve mechanism (64) is controlled by the control ring (20) is formed. Variable displacement lubrication pump (10). claim 4 , wherein the application valve mechanism (64) is defined by a fixed application groove (54) on the pump housing side formed on a housing sliding surface (58) of the pump housing (16) and by a corresponding movable application groove (52) on the control ring side formed on a control ring sliding surface (56) of the control ring (20). is, wherein the two corresponding loading grooves (52, 54) are formed such that - that they overlap when the control ring (20) is positioned between the position of maximum eccentricity and a loading channel closed position to form a lubricant passage (68) which one allowing lubricant flow between the two biasing grooves (52, 54), and - that they do not overlap when the control ring (20) is positioned between the biasing channel closed position and the position of minimum eccentricity to allow lubricant flow between the two biasing grooves (52, 54). impede. Lubricant pump (10) with variable displacement according to claims 3 and 5 , wherein the evacuation channel opening position and the admission channel closing position essentially correspond. Variable displacement lubrication pump (10). claim 5 or 6 , wherein the pump housing-side loading groove (54) is substantially transverse to the direction of displacement (S), and wherein the control ring-side loading groove (52) comprises a passage section (55) which extends essentially parallel to the pump housing-side loading groove (54). A variable displacement lubricant pump (10) according to any one of the preceding claims, wherein there is a separate auxiliary pilot chamber (42) arranged to be subjected to an auxiliary pilot chamber hydraulic pressure during pumping operation and arranged to be intermittently fluidly connected via an auxiliary pilot chamber loading line (46). to be connected to high pressure, wherein the auxiliary pilot chamber (42) is formed such that the control ring (20) is urged toward the minimum eccentricity position by the auxiliary pilot chamber hydraulic pressure.

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