EP3377765B1

EP3377765B1 - A variable displacement lubricant pump

Info

Publication number: EP3377765B1
Application number: EP15797106.0A
Authority: EP
Inventors: Carmine Cuneo
Original assignee: Pierburg Pump Technology GmbH
Current assignee: Pierburg Pump Technology GmbH
Priority date: 2015-11-19
Filing date: 2015-11-19
Publication date: 2020-01-01
Anticipated expiration: 2035-11-19
Also published as: EP3377765A1; WO2017084710A1

Description

The present invention refers to a variable displacement lubricant pump for providing pressurized lubricant for an internal combustion engine.
The mechanical lubricant pump is mechanically driven by the engine and comprises a pump rotor with radially slidable vanes rotating in a radially shiftable control ring, whereby the control ring is pushed by a pressure control chamber into high pumping volume direction. The pump is provided with a pressure control system for controlling the discharge pressure of the pressurized liquid lubricant at the pump outlet port. The pump is provided with a pressure conduit for connecting an actual pressure pickup with the pressure control chamber, and the pump is also provided with a pressure control valve and a control valve, which control the pressure in the pressure control chamber.
WO 2012/113437 discloses a variable lubricant pump, which provides two levels of nominal pressure of the pressurized lubricant leaving the pump. The lubricant pump comprises a pump rotor with radially slidable vanes rotating inside a shiftable control ring which is radially shiftable or pivotable with respect to the rotor axis between a high pumping volume position and a low pumping volume position. The pump comprises a pressure control system for controlling the discharge pressure of the pressurized lubricant at the pump outlet. The pressure control system comprises a fluidic pressure control chamber for pushing the shiftable control ring into high pumping volume direction. The pressure control system also comprises a fluidic pilot chamber for pushing the control ring into a low pumping volume direction against the forces generated by the pressure control chamber. The pressure control chamber is an antagonist of the pilot chamber. The pilot chamber as well as the pressure control chamber are directly fluidically charged with the discharge pressure.
WO2015/074700 , WO2013/093711 and WO2010/006705 disclose variable displacement lubricant pumps and the associated processes for controlling the pumps' displacement of the background art.
The object of the present invention is to provide a variable displacement lubricant pump with a simple control system which provides three different levels of nominal pressure of the pressurized lubricant leaving the pump.
This object is solved with a variable-displacement lubricant vane pump having the features of claim 1.
The variable displacement lubricant pump is provided with a pump rotor with radially slidable vanes rotating in a shiftable control ring. The pump is provided with a pressure control chamber for pushing the control ring into a high pumping volume direction. The pressure control chamber is connected to an actual pickup pressure source by a pressure conduit. According to the invention an actual pickup pressure source is the source from which the pressure for controlling the control chamber is used. Examples for the actual pickup pressure source are the pump outlet port or an engine main gallery.
The pressure control valve for controlling the pressure in the pressure control chamber comprises a control plunger, an input pressure plunger and a control spring. Dependent on the position the control plunger a first control port or a second control port is opened, alternatively. Both ports are provided in a cylinder wall of the pressure control valve and are both connected with an outlet port of the pressure control chamber. In an opened state of the first- or second control port a fluidic connection is established to a first- or second discharge port provided in a cylinder wall of the pressure control valve. The first discharge port is connected to a set value control valve, which in an opened state establishes a fluidic connection from the discharge port to the lubricant tank having atmospheric pressure.
The second discharge port has preferably a direct fluidic connection to the lubricant tank.
The input pressure plunger is directly mechanically connected with the control plunger so that a high pressure in the input pressure chamber forces the control plunger into a closed position with respect to the first control port. A control spring is provided, which preloads the control plunger against the pressure in the input pressure chamber. The spring force of the control spring and the pressure in the input pressure chamber acting on the input pressure plunger, force the control plunger into an equilibrium position.
The pressure in the input pressure chamber is dependent on a discharge pressure of the pump, which is applied to the input pressure chamber. The pressure in the input pressure chamber further is dependent on a lubricant outflow rate of the lubricant flowing from the input pressure chamber to the lubricant tank. The lubricant outflow either is enabled or disabled by opening or closing the set value control valve.
When the internal combustion engine is off the lubricant pump is not rotating and the control plunger is in an idle position. Further, the set value control valve is in an opened state. By starting the combustion engine the lubricant pump starts pumping lubricant. The lubricant pressure thereby increases to a low discharge pressure level.
When, at a low discharge pressure level, the set value control valve is closed the discharge pressure level changes to an intermediate pressure level. In a closed state of the set value control valve a lubricant flow from the input pressure chamber to the lubricant tank is disabled. Further, also a lubricant flow from the first discharge port to the lubricant tank is disabled. Thus, the pressure in the input pressure chamber and the pressure control chamber increases. The pressure in the input pressure chamber moves the control plunger in the direction towards the spring.
The pressure in the pressure control chamber pushes the control ring to a higher pumping volume direction. Thereby also the discharge pressure of the pump will be increased. The discharge pressure will be increased until an intermediate discharge pressure level is achieved. The intermediate discharge pressure level is achieved when the control plunger closes the first control port and opens the second control port. By opening the second control port a fluidic connection between the pressure control chamber and the lubricant tank is established.
When, at an intermediate discharge pressure level, the set value control valve is opened the discharge pressure level changes to a high pressure level. In an opened state of the set value control valve a lubricant flow from the input pressure chamber to the lubricant tank is enabled. Thus, the pressure in the input pressure chamber decreases. The control plunger thereby is temporarily forced by the spring in the direction toward the input pressure chamber. The second control port will be further narrowed so that the fluid rate of the fluid leaving the pressure control chamber decreases and thus the pressure in the pressure control chamber increases. The pressure in the pressure control chamber pushes the control ring to the high pumping volume direction. Thereby, also the discharge pressure will be increased. This leads to a movement of the control plunger in the direction to the spring. The discharge pressure will be increased until the high discharge pressure level is achieved.
When, at a high discharge pressure level, the set value control valve is closed the discharge pressure level changes to an intermediate pressure level. In a closed state of the set value control valve a lubricant flow from the input pressure chamber to the lubricant tank is disabled. Thus, the pressure in the input pressure chamber increases. The pressure in the input pressure chamber thereby temporarily moves the control plunger in the direction to the spring. An orifice of the second control valve will be fully opened so that the lubricant flow from the pressure control chamber to the lubricant tank is increased and the pressure in the pressure control chamber decreases. The control ring thereby moves to a low pumping volume direction. Further, also the discharge pressure will be decreased leading to a movement of the control plunger in the direction to the input pressure chamber and the control ring to a low pumping volume direction. The discharge pressure will be decreased until an intermediate discharge pressure level is achieved.
The variable displacement lubricant pump according to the present invention therefore can provide three different discharge pressure levels. The discharge pressure can be changed to the intermediate pressure level and to the high pressure level by simply switching a set value control valve. The low pressure level is available after starting the engine. After the pressure has been increased to an intermediate level the low pressure level can be set after restarting the engine or if the engine pressure is below the low pressure level.
According to a preferred embodiment of the present invention the set value control valve is a solenoid valve. A solenoid valve has the advantage that a fast switching of the valve is possible.
Preferably a throttle valve is provided in flow direction before the input pressure chamber. A throttle valve according to the invention is a calibrated orifice, which reduces the flow cross section in an unchangeable manner so that a defined pressure loss is generated. Therefore it is possible to adjust the pressure in flow direction behind the throttle valve. A respective throttle valve is preferably also provided in flow direction behind the input pressure chamber.
In a preferred embodiment of the present invention a pilot chamber is provided, which is connected to the pump outlet port and is pushing the control ring into the low pumping volume direction.
According to a preferred embodiment of the invention, the control ring is pretensioned by a spring into the high pumping volume direction. The spring is an antagonist of the pilot chamber.
Preferably the second discharge port is directly connected to the lubricant tank.
In a further preferred embodiment of the present invention an electronic control device is connected to a lubricant temperature sensor and controlling the outlet valve. The lubricant temperature sensor detects the temperature of the lubricant in the engine. Dependent on this temperature value the electronic control device decides whether to open or to close the set value control valve in order to change the discharge pressure level of the pump.
In an alternative embodiment the electronic control device is connected to a speed sensor and controlling the outlet valve. The speed sensor detects the speed of an e.g. vehicle. Dependent on the speed value the electronic control device decides whether to open or to close the set value control valve in order to change the discharge pressure level of the pump.
In a further preferred embodiment an engine load sensor is provided. Dependent on a detected engine load value the electronic control device decides whether to open or to close the set value control valve in order to change the discharge pressure level of the pump.
In a further alternative embodiment a pressure sensor is provided. Dependent on a detected pressure value the electronic control device decides whether to open or to close the set value control valve in order to change the discharge pressure level of the pump.
The following is a detailed description of an embodiment of the invention with reference to the drawings, wherein:

Figure 1 shows the variable displacement lubricant pump at a low pressure discharge state,
Figure 2 shows the variable displacement lubricant pump at an intermediate pressure discharge state, and
Figure 3 shows the variable displacement lubricant pump at a high pressure discharge state.

Figure 1 shows a schematic representation of a variable displacement lubricant pump 10 for supplying an internal combustion engine 12 with pressurized lubricant. The pump 10 comprises a pumping unit 14, which is mechanically driven by the engine 12. The pumping unit 14 comprises a housing 40 having a cavity 41 in which a control ring 42 translates, which encircles a pump rotor 44. The pump rotor 44 is provided with numerous radially slidable vanes 46, whereby the vanes 46 are rotating inside the control ring 42. The control ring 42 is radially shiftable so that the eccentricity of the control ring 42 with respect to a rotation axis 47 of the pump rotor 44 can be set to thereby shift the control ring between a low pumping volume at low eccentricity position and a high pumping volume position at high eccentricity.
The housing 40 is closed by two side walls 48 of which one is not shown in the drawing. The side walls 48, the vanes 46, the pump rotor 44 and the control ring 42 define five rotating pump chambers 50.
The control ring 42 is provided with a first control ring plunger 52 housed in a pressure control chamber 54 and is provided with a second control ring plunger 55 housed in a pilot chamber 56. The pilot chamber 56 is provided opposite to the pressure control chamber 54. The control ring 42 and the plungers 52, 55 are one single integral part.
A pretensioned control chamber spring 57 inside the pressure control chamber 54 exerts a pushing force to the first control ring plunger 52. The pressure control chamber 54 is defined by the housing 40. The housing 40 also comprises a inlet port 58 for sucking the lubricant from a lubricant tank 60 and a outlet port 62 for feeding lubricant with a discharge pressure to the engine 12. An engine supply conduit 64 extends from the outlet port 62 to the engine 12 to supply the engine 12 with pressurized lubricant.
The lubricant discharge pressure at the outlet port 62 is transmitted to the pressure control chamber 54 via a conduit 66, 68 and through a pressure throttle valve 70 in which a calibrated pressure drop occurs as the lubricant flows through. The lubricant discharge pressure is also transmitted to the pilot chamber 56 via a pilot chamber conduit 71.
The outlet port 62 is also connected via a conduit 66, 72 and through a pressure throttle valve 74 to an input pressure port 76 of a pressure control valve 78. The pressure control valve 78 keeps the outlet pressure at the outlet port 62 at a constant nominal pressure value independently of the rotational speed of the engine 12 by regulating the radial position of the control ring 42. The radial position of the control ring 42 is controlled by controlling the pressure in the pressure control chamber 54.
The pressure in the pressure control chamber 54 is regulated by controlling a lubricant discharge of an outlet port 79 of the pressure control chamber 54 via conduit 80, 81 by closing and opening a first control port 82 and a second control port 83 in a cylinder wall 84 of a pressure control valve housing 85.
Dependent on the axial position of a control plunger 86 in the pressure control valve housing 85, the first or the second control port 82, 83 is open and the other port 83, 82 is closed. The position of the control plunger 86 is dependent on a pressure in an input pressure chamber 88, which pressure thereby is charged to an input pressure plunger 90 and on a preload applied to the control plunger 86 by a control spring 92. The control spring 92 acts against the pressure in the input pressure chamber 88. The input pressure plunger 90 is mechanically directly connected with the control plunger 86 so that a high pressure in the input pressure chamber 88 forces the control plunger 86 in a closed position with respect to the first control port 82. Figure 1 shows a position of the control plunger 86 in which the first control port 82 is open, while the second control port 83 is closed. The first control port 82 thereby is fluidically connected through a first discharge port 94 in the cylinder wall 84 of the pressure control valve 78 to a solenoid valve as a set value control valve 96. The solenoid valve is controlled by an electronic control device 97, which is connected to a lubricant temperature sensor 98. The lubricant temperature sensor 98 measures the temperature of the lubricant in the engine 12. In figure 1 the solenoid valve is in an open state so that the pressure control chamber 54 is fluidically connected by the open first control port 82 to the lubricant tank 60.
The input pressure chamber 88 is connected via a conduit 99 and through a pressure throttle valve 100 to the solenoid valve. If the solenoid valve in figure 1 is in an open state, the input pressure chamber 88 is fluidically connected to the lubricant tank 60.
By closing the solenoid valve the input pressure chamber 88 and the first control port 82 are fluidically disconnected from the lubricant tank 60. Thereby the pressure in the input pressure chamber 88 and in the pressure control chamber 54 increases. The pressure in the input pressure chamber 88 moves the control plunger 86 in the direction to the control spring 92. The pressure in the pressure control chamber 54 pushes the control ring 42 to a high pumping volume direction. Thereby also the discharge pressure of the pumping unit 14 increases leading to a further movement of the control plunger 86. The discharge pressure will be increased until a new equilibrium plunger position is achieved. The new equilibrium position is achieved when the control plunger 86 closes the first control port 80 and opens the second control port 83. By opening the second control port 83 a fluidic connection of the pressure control chamber 54 via a second discharge port 102 in the cylinder wall 84 of the pressure control valve 78 to the lubricant tank 60 is established. In figure 2 a respective equilibrium situation is achieved. In this state the pumping unit 14 discharges at an intermediate pressure.
By opening the solenoid valve in a state of an intermediate pressure the input pressure chamber 88 is again fluidically connected to the lubricant tank 60. Thereby the pressure in the input pressure chamber 88 decreases. The control plunger 86 thereby is temporarily forced by the control spring 92 in the direction to the input pressure chamber 88. The second control port 82 further will be narrowed so that less fluid leaves the pressure control chamber 54 and the discharge pressure increases. The pressure in the pressure control chamber 54 pushes the control ring 42 to a high pumping volume direction. Thereby also the discharge pressure will be increased leading to a movement of the control plunger 86 in the direction to the control spring 92 and of the control ring 42 to a high pumping volume direction. The discharge pressure will be increased until an equilibrium situation is achieved. In figure 3 a respective equilibrium situation is achieved. In this state the pump discharges a high discharge pressure.

Reference signs

10: variable displacement lubricant pump
12: combustion engine
14: pumping unit
40: housing
41: cavity
42: control ring
44: pump rotor
46: vanes
47: rotation axis
48: side wall
50: pump chambers
52: first control ring plunger
54: pressure control chamber
55: second control ring plunger
56: pilot chamber
57: control chamber spring
58: inlet port
60: lubricant tank
62: outlet port
64: engine supply conduit
66: conduit
68: conduit
70: pressure throttle valve
71: pilot chamber conduit
72: conduit
74: pressure throttle valve
76: input pressure port
78: pressure control valve
79: outlet port
80: conduit
81: conduit
82: first control port
83: second control port
84: cylinder wall
85: pressure control valve housing
86: control plunger
88: input pressure chamber
90: input pressure plunger
92: control spring
94: first discharge port
96: set value control valve
97: electronic control device
98: temperature sensor
99: conduit
100: pressure throttle valve
102: second discharge port

Claims

A variable displacement lubricant pump (10) fluidically coupled to and mechanically driven by an internal combustion engine (12) for pumping pressurized lubricant to the engine (12), comprising:
- a pump rotor (44) with radially slidable vanes (46) rotating in a shiftable control ring (42) being radially shiftable or pivotable with respect to the rotor axis (47) between a high pumping volume position and a low pumping volume position,

- a pressure control system for controlling the discharge pressure of the pressurized lubricant, the control system comprising:
- a pressure control chamber (54) for pushing the control ring (42) into high pumping volume direction,

- a pressure conduit (66, 68) for connecting an actual pickup pressure source with the pressure control chamber (54), and

- a pressure control valve (78) controlling the pressure in the pressure control chamber (54), the pressure control valve (78) comprising:
- a control plunger (86), which is movable between a first position, where a first control port (82) in a cylinder wall (84) of the pressure control valve (78) is connected to a first discharge port (94) in the cylinder wall (84) and a second control port (83) in the cylinder wall (84) is closed, and a second position where the first control port (82) is closed and the second control port (83) is connected to a second discharge port (102) in the cylinder wall (84), whereby the first and the second control ports (82, 83) are connected with an outlet port (79) of the pressure control chamber (54),

- an input pressure plunger (90) being charged with a pressure in an input pressure chamber (88) supplied by a pump outlet port (62), wherein the input pressure plunger (90) is mechanically connected with the control plunger (86), and

- a control spring (92) preloading the control plunger (86) into the first position against the pressure in the input pressure chamber (88),

- a set value control valve (96) which is switchable between an open and a closed state, wherein in the open state the set value control valve (96) fluidically connects the first discharge port (94) and the input pressure chamber (88) both with a lubricant tank (60).
The variable displacement lubricant pump (10) according to claim 1, characterized in that the set value control valve (96) is a solenoid valve.
The variable displacement lubricant pump (10) of one of the preceding claims, characterized in that a throttle valve (74) is provided in flow direction before the input pressure chamber (88).
The variable displacement lubricant pump (10) of one of the preceding claims, characterized in that a throttle valve (100) is provided in flow direction behind the input pressure chamber (88).
The variable displacement lubricant pump (10) of one of the preceding claims, characterized by a pilot chamber (56) connected to the pump outlet port (62) and pushing the control ring (42) into low pumping volume direction.
The variable displacement lubricant pump (10) of one of the preceding claims, characterized in that the control ring (42) is pretensioned by a spring (57) into the high pumping volume direction.
The variable displacement lubricant pump (10) of one of the preceding claims, characterized in that the second discharge port (102) is directly connected to the lubricant tank (60).
The variable displacement lubricant pump (10) of one of the preceding claims, characterized in that a throttle valve (70) is provided in flow direction before the control chamber (54).
The variable displacement lubricant pump (10) of one of the preceding claims, characterized by an electronic control device (97) connected to a lubricant temperature sensor (98) and controls the set value control valve (96).
The variable displacement lubricant pump (10) of claims 1 to 8, characterized by an electronic control device (97) connected to a speed sensor and controls the set value control valve (96).
The variable displacement lubricant pump (10) of claims 1 to 8, characterized by an electronic control device (97) connected to an engine load sensor and controls the set value control valve (96).
The variable displacement lubricant pump (10) of claims 1 to 8, characterized by an electronic control device (97) connected to a pressure sensor and controls the set value control valve (96).