DE112017007483T5 - Adjustable liquid displacement pump - Google Patents

Abstract

The disclosure relates to an adjustable fluid displacement pump (10) for pumping pressurized fluid, comprising a pump rotor (44) with radially displaceable slides (46) rotating in a displaceable control ring (42), a pressure control system for controlling the outlet pressure the pressurized liquid. The control system includes a pressure control chamber (54) for pushing the control ring (42) in one direction for a large flow and a pressure control valve (78) which controls the pressure in the pressure control chamber (54). The pressure control valve (78) comprises a control tappet (86) which is movable between a first position and a second position, an inlet pressure tappet (90) which is acted upon by an actual pressure (PA) in an inlet pressure chamber (88), the Inlet pressure tappet (90) is mechanically connected to the control tappet (86), and a control valve spring (92) which biases the control tappet (86) against the pressure in the input pressure chamber (88) to the second position. The control system further comprises a separate damping unit (100) which comprises a piston (108) which moves in a separate damping chamber (112) and which divides the damping chamber (112) into two chamber parts (112a, 112b) which are passed through a damping channel ( 118; 120) are fluidly connected to one another, with the piston (108) being rigidly connected to the control tappet (86).

Description

Adjustable liquid displacement pump

The present invention relates to an adjustable liquid displacement pump for pumping pressurized liquid.

An adjustable fluid displacement pump is mechanically driven by the motor and includes a pump rotor with radially slidable vanes that rotate in a slidable control ring, thereby pushing the control ring in one direction for a large flow rate through a pressure control chamber. The pump is provided with a pressure control system for controlling the outlet pressure of the pressurized liquid at the pump outlet connection. The pump is equipped with a pressure control valve that controls the pressure in the pressure control chamber. The pressure control valve includes a plunger that is preloaded by a control valve spring.

According to the present invention, the term “radially displaceable slide valve” also includes radially displaceable pendulum slide valve, wherein the orientation of the slide valve does not have to be understood as exactly radial, but can have a constant or variable component in a radial direction.

The WO 2014/187503 A1 describes an adjustable lubricant pump which comprises a pump rotor with radially displaceable slides, the pump rotor rotating in a displaceable control ring. The control ring is slidable between a large delivery position and a small delivery position.

The pump includes a pressure control system that includes a pressure control chamber for pushing the control ring to a large delivery position. The control system further includes a pressure control valve that controls the pressure in the pressure control chamber. A control piston is slidably provided in the control valve to open and close an outlet port of the pressure control chamber and thereby control the pressure in the pressure control chamber. The control piston is preloaded at one axial end by a spring.

The lubricant pressure at the engine lubricant outlet is advantageously used as the control variable to be controlled by the pressure control circuit. This concept ensures sufficient lubricant pressure in the engine. Since the actual lubricant pressure is tapped at the engine lubricant outlet, the control loop is more susceptible to pressure fluctuations.

The fluid displacement pump according to the prior art has fluctuations in the lubricant outlet pressure in the range from 5 to 50 Hz. The fluctuations in the outlet pressure are around an average pressure value that is below the set pressure value at high speed. As a result, the average pressure value at a high speed is lower than expected.

The object of the present invention is to provide an adjustable liquid displacement pump with improved pressure stability.

This object is achieved by an adjustable liquid displacement pump with the features of claim 1.

According to the present invention, the adjustable liquid displacement pump is provided with a separate damping unit. Accordingly, the damping unit is not integrated in the pressure control valve, but is provided as a separate unit of the pressure control system. The damping unit comprises a piston which moves in a separate damping chamber and which divides the damping chamber into two chamber parts which are fluidly connected by a damping channel. A pressure difference between the two chamber parts is compensated for via the damping channel. The temporal behavior of the compensation of the pressure difference between the chamber parts depends on the geometry and the design of the damping channel and on the damping fluid. As a result, the temporal behavior can be influenced by the geometry and the design of the damping channel and the nature and viscosity of the damping fluid. High-frequency movements of the piston in the damping chamber are therefore damped. The piston of the damping unit is rigidly connected to the control tappet, so that the movement of the control tappet is also damped. High-frequency vibrations of the control tappet, which lead to a fluctuating outlet pressure, are therefore damped and reduced. As a result, the adjustable liquid displacement pump has a higher pressure stability at a high speed of the pump.

According to a preferred embodiment of the present invention, the liquid pump is a lubricant pump.

The control valve spring is preferably provided in the pressure control valve. With this arrangement, the damping unit can be easily added to an existing pressure control valve.

In an alternative embodiment, the control valve is provided in the damping chamber. The control valve spring is thereby provided in a chamber part, preferably in the chamber part which is located at a free axial end of the damping chamber. As a result, easy access to the control valve spring from the free axial end is possible. Therefore, the control valve spring can be easily replaced, for example to adjust the spring constant.

In a preferred embodiment of the present invention, a damping fluid in the damping chamber is the pump liquid. Accordingly, no separate damping fluid is required.

According to a further preferred embodiment, a damping fluid in the damping chamber is oil. In contrast to gas, oil is not compressible, so that no additional spring action is provided by using oil as a damping fluid.

Furthermore, oil has a high boiling point, so that oil has a large working range.

According to an alternative embodiment, a damping fluid in the damping chamber is air. The viscosity of air increases slightly with increasing temperature, so that the damping effect does not decrease with increasing temperature, in contrast to liquids.

In another alternative embodiment, a damping fluid in the damping chamber is fat. Fat is a fluid with a high viscosity, so that a high damping effect can be achieved.

The piston and the control plunger are preferably mechanically connected to one another by a rigid rod. A rod is a simple structural element for rigidly connecting the control tappet and the piston.

According to a preferred embodiment of the invention, a damping channel is provided as an axial bore in the piston. The piston can be easily drilled so that manufacture is easy. Furthermore, the bore can be adapted to different viscosities of the damping fluid by providing an adapted geometry of the bore.

In a further preferred embodiment of the present invention, the damping channel is provided as a radial space between the piston and a damping chamber wall. The radial space can be provided by selecting an outer radius for the piston that is substantially smaller than an inner radius of the damping chamber, so that a gap is defined between the damping chamber wall and the piston. A seal provided on the outer peripheral surface of the piston is not necessary. Furthermore, there is no friction.

In a preferred embodiment of the present invention, the coefficient of thermal expansion of the piston and the housing of the damping chamber differ from one another, so that the radial space varies with varying temperature. Since the viscosity of the damping fluid, such as oil, decreases with increasing temperature, it is possible to reduce the radial gap in order to adapt the radial gap to the viscosity of the damping oil. As a result, an essentially stable damping effect is realized over a wide temperature range.

The outlet connection is preferably connected directly to a liquid tank.

The control ring is preferably biased by a spring in the direction of large flow. The spring is an antagonist for a pilot chamber and interacts with the control chamber.

The actual pressure is preferably the lubricant outlet pressure of the engine at the engine lubricant outlet. The pilot pressure is not the pump outlet pressure, but the engine's lubricant outlet pressure. This prevents the lubricant pressure in the engine from falling below a certain value. By using the lubricant pressure at the engine lubricant outlet as the actual pressure, a certain dead time is generated in the control circuit. As a result, the control loop becomes more susceptible to lubricant pressure fluctuations. In the present invention, these fluctuations in the lubricant pressure in the engine are reduced.

• 1 eine erste Ausführungsform der Fluidverstellpumpe in einem offenen Zustand des Drucksteuerventils,
• 2 die Ausführungsform nach 1 in einem geschlossenen Zustand des Drucksteuerventils,
• 3 eine zweite Ausführungsform der Fluidverstellpumpe in einem offenen Zustand des Drucksteuerventils und
• 4 eine vergrößerte Ansicht der Dämpfungseinheit gemäß einer dritten Ausführungsform der Fluidverstellpumpe.

Further advantages will appear from the following detailed description of the embodiments of the present invention in combination with the drawings; show in it:

• 1 1 a first embodiment of the fluid adjustment pump in an open state of the pressure control valve,
• 2 the embodiment according to 1 in a closed state of the pressure control valve,
• 3 a second embodiment of the fluid variable displacement pump in an open state of the pressure control valve and
• 4 an enlarged view of the damping unit according to a third embodiment of the fluid pump.

1 shows a schematic representation of an adjustable fluid pump 10 , The adjustable fluid pump 10 is a lubricant positive displacement pump 10 for supplying an internal combustion engine 12 with pressurized lubricant. The pump 10 includes a pump unit 14 by the engine 12 is mechanically driven. The pump unit 14 includes a housing 40 with a cavity 41 in which there is a pump rotor 44 surrounding control ring 42 shifts translationally. The pump rotor 44 is with numerous radially movable sliders 46 provided, the slider 46 in the control ring 42 rotate. The control ring 42 is radially displaceable, so that the eccentricity of the control ring 42 with respect to an axis of rotation 47 of the pump rotor 44 can be adjusted, the control ring 42 to move between a small delivery position in a low eccentricity position and a large delivery position in a high eccentricity position.

The housing 40 is through two side walls 48 closed, one of which is not shown in the drawings. The sidewalls 48 who have favourited Sliders 46 , the pump rotor 44 and the control ring 42 define five rotating pump chambers 50 ,

The control ring 42 is with a first control ring tappet 52 provided in a pressure control chamber 54 is housed, and with a second control ring tappet 55 provided in a pre-tax chamber 56 is housed. The pre-tax chamber 56 is opposite the pressure control chamber 54 intended. The control ring 42 and the pestle 52 . 55 are one integral part.

A preloaded control chamber spring 57 in the pressure control chamber 54 exerts a compressive force on the first control ring tappet 52 out. The pressure control chamber 54 is through the housing 40 Are defined. The housing also includes 40 an inlet port 58 for sucking in the lubricant from a lubricant tank 60 and an outlet port 62 to supply the motor 12 with lubricant with an outlet pressure. An engine feed line 64 extends from the outlet port 62 to the engine 12 to the engine 12 supply pressurized lubricant.

An actual pressure PA at an engine lubricant outlet 65 is over a line 66 . 67 . 68 and through a pressure throttle valve 70 where there is a calibrated pressure drop as the lubricant flows through to the pressure control chamber 54 transfer. The actual pressure PA is also via a pilot chamber line 71 to the pre-tax chamber 56 transfer.

The actual pressure PA will also have a line 66 . 72 to an inlet pressure connection 76 a pressure control valve 78 transfer. The pressure control valve 78 maintains the actual pressure PA at the engine lubricant outlet 65 regardless of the speed of the engine 12 at a constant nominal pressure value by changing the radial position of the control ring 42 regulated. The radial position of the control ring 42 is done by controlling the pressure in the pressure control chamber 54 controlled.

The pressure in the pressure control chamber 54 is accomplished by controlling lubricant delivery of an outlet port 79 the pressure control chamber 54 over a line 81 to one in a cylinder wall 84 a pressure control valve body 85 provided control connection 83 regulated.

Depending on the axial position of a control tappet 86 in the pressure control valve housing 85 becomes an outlet connection 87 opened or closed. The position of the ram 86 depends on a pressure in an inlet pressure chamber 88 , with an input plunger 90 thereby being pressurized, and by a control valve spring 92 on the control tappet 86 applied preload.

The control valve spring 92 acts against the pressure in the inlet pressure chamber 88 , The inlet pressure ram 90 is mechanically direct with the control tappet 86 connected so that a high pressure in the input pressure chamber 88 the control tappet 86 regarding the outlet connection 87 forces into an open position. 1 shows a position of the control tappet 86 in which the outlet connection 87 is open so that the lubricant via an outlet line 93 to the lubricant tank 60 is delivered.

For damping small pressure fluctuations of the adjustable lubricant displacement pump 10 is the outlet pressure of the pressurized lubricant through a damping unit 100 that are on one axial end of the control valve 78 is arranged, further controlled. The control valve 78 is through a static partition 104 fluidic from the damping unit 100 Cut. The damping unit 100 includes a piston 108 that over a pole 110 with the control tappet 86 is rigidly connected and in one by a housing 113 the damping unit 100 formed separate damping chamber 112 emotional. The damping piston 108 divided the with lubricant fluid as a damping chamber filled with damping fluid 112 in two chamber parts 112a . 112b , Both parts of the chamber 112a . 112b are through one as a bore in the piston 108 provided damping channel 118 fluidly connected. If the pressure in the inlet pressure chamber 88 changes, the damping piston 108 in the direction of one of the two chamber parts 112a . 112b forced so that the damping fluid from one chamber part 112a to the other part of the chamber 112b flows. During the damping fluid slowly through the damping channel 118 from a chamber part 112a to the other part of the chamber 112b flows, the movement of the piston 108 and thus the control tappet 86 attenuated. Accordingly, small fluctuations in high-frequency pressure do not have a strong effect on the movement of the control tappet 86 , As a result, even at a high speed of the pump rotor 44 a more uniform outlet pressure of the pump is realized.

2 shows the adjustable lubricant positive displacement pump 10 to 1 in a closed state of the pressure control valve 78 , In this state the control valve spring has 92 the control tappet 86 in the direction of the inlet pressure chamber 88 emotional. This closes the control tappet 86 the outlet connection 87 so no lubricant from the control chamber 54 to the lubricant tank 60 is delivered.

3 shows a second embodiment of the adjustable lubricant positive displacement pump 10 in an open state of the pressure control valve 78 , The control valve spring 92 is in the distal part of the chamber 112b the damping unit 100 provided so that the control valve spring 92 the damping piston 108 in a direction towards the inlet pressure chamber 88 preloaded.

4 shows an enlarged view of the damping unit 100 according to a third embodiment of the adjustable lubricant displacement pump 10 , The damping channel 120 is as a radial space between the pistons 108 and a chamber wall 124 the damping chamber 112 intended.

It should be obvious that the invention is not limited to the described embodiment. In particular, various structural changes and modifications are possible that fall within the scope of the present invention. For example, the actual pressure can also be measured directly at the pump outlet connection.

LIST OF REFERENCE NUMBERS

10

Adjustable lubricant positive displacement pump

12

internal combustion engine

14

pump unit

40

casing

41

cavity

42

control ring

44

pump rotor

46

pusher

47

axis of rotation

48

Side wall

50

pump chambers

52

first control ring tappet

54

Pressure control chamber

55

second control ring tappet

56

pilot chamber

57

Control chamber spring

58

inlet port

60

lubricant tank

62

outlet

64

Motor supply line

65

Motorschmiermittelauslass

66

management

67

management

68

management

70

Pressure throttle valve

71

Pilot chamber line

72

management

76

Inlet pressure port

78

Pressure control valve

79

outlet

81

management

83

control connection

84

cylinder wall

85

Pressure control valve housing

86

control tappet

87

outlet connection

88

Inlet pressure chamber

90

Inlet pressure plunger

92

Control valve spring

100

damping unit

104

partition wall

108

piston

110

pole

112

damping chamber

112a

chamber member

112b

chamber member

113

casing

118

damping channel

120

damping channel

124

chamber wall

PA

Actual pressure

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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 2014/187503 A1 [0004]

Claims (15)

An adjustable fluid displacement pump (10) mechanically driven by an internal combustion engine (12) for pumping pressurized fluid, comprising: - A pump rotor (44) with radially displaceable slides (46) which rotate in a displaceable control ring (42) which is radially displaceable or pivotable with respect to the axis of rotation (47) between a position for a large delivery quantity and a position for a small delivery quantity is and a pressure control system for controlling the outlet pressure of the pressurized liquid, the control system comprising: - A pressure control chamber (54) for pushing the control ring (42) in one direction for a large flow rate, and a pressure control valve (78) that controls the pressure in the pressure control chamber (54), the pressure control valve (78) comprising: - A control tappet (86), which is connected between a first position, in which a control connection (83) in a cylinder wall (84) of the pressure control valve (78) is connected to an outlet connection (87) in the cylinder wall (84), and a second position , in which the outlet connection (87) is closed, is movable, the control connection (83) being connected to an outlet connection (79) of the pressure control chamber (54), - An inlet pressure tappet (90) which is acted upon by an actual pressure (PA) in an inlet pressure chamber (88), the inlet pressure tappet (90) being mechanically connected to the control tappet (86), and - a control valve spring (92) biasing the control plunger (86) against the pressure in the input pressure chamber (88) to the second position; and - A separate damping unit (100), which comprises a piston (108) which moves in a separate damping chamber (112) and which divides the damping chamber (112) into two chamber parts (112a, 112b) which pass through a damping channel (118; 120 ) are fluidly connected to one another, divided, the piston (108) being rigidly connected to the control tappet (86). Adjustable liquid displacement pump (10) according to Claim 1 , characterized in that the liquid pump (10) is a lubricant pump. Adjustable liquid displacement pump (10) according to Claim 1 or 2 , characterized in that the control valve spring (92) is provided in the pressure control valve (78). Adjustable liquid displacement pump (10) according to Claim 1 or 2 , characterized in that the control valve spring (92) is provided in the damping chamber (112). Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that a damping fluid in the damping chamber (112) is the pump liquid. Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that a damping fluid in the damping chamber (112) is oil. Adjustable liquid displacement pump (10) according to one of the Claims 1 to 5 , characterized in that a damping fluid in the damping chamber (112) is air. Adjustable liquid displacement pump (10) according to one of the Claims 1 to 5 , characterized in that a damping fluid in the damping chamber (112) is fat. Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that the piston (108) and the control plunger (86) are mechanically connected to one another by a rod (110). Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that the damping channel (118) is provided as a bore in the piston (108). Adjustable liquid displacement pump (10) according to one of the Claims 1 to 9 , characterized in that the damping channel (120) is provided as a radial space between the piston (108) and a damping chamber wall (124). Adjustable liquid displacement pump (10) according to Claim 11 , characterized in that the coefficient of thermal expansion of the piston (108) and a housing (113) of the damping chamber (112) differ from one another, so that the radial space (120) varies with varying temperature. Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that the outlet connection (87) is connected directly to a liquid tank (60). Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that the control ring (42) is biased in the direction of a large delivery rate by a spring (57). Adjustable liquid displacement pump (10) according to one of the preceding claims, characterized in that the actual pressure (PA) is the lubricant outlet pressure of the motor (12).

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