Patent Application
20200102862
The invention relates to an oil distributor for a lubricating and cooling system in a powertrain, a lubricating and cooling system in a powertrain comprising such an oil distributor, a powertrain, a vehicle and a method of controlling a lubricating and cooling system in a powertrain according to the appended claims.
In vehicles, and especially for heavier vehicles such as trucks, an oil distributor may be arranged for supplying oil to powertrains provided with an internal combustion engine and/or an electrical machine. The oil distributor may secure oil pressure and oil flow for lubricating and/or cooling the electric machines, bearings and gears using the same transmission oil.
Vehicles may also be equipped with a multispeed transmission. For different scenarios the oil distributor may split one oil flow from one single oil pump in two different oil circuits. The same oil distributor may also be able to change or switch oil circuit from the oil pump for the most robust and energy efficient option. Therefore, the oil distributor may have at least one oil inlet but have two separated oil chambers and two oil outlets connected to different oil circuits.
Known transmission oil circuits may be divided into several oil circuits which are connected to each other with a geometrical change such as a smaller cross section channel to create an increased pressure and therefore push oil into next circuit or channel until all components that should be lubricated are provided with oil. Such system may require a high oil pressure. Components that may be lubricated are bearings and gears. Instead of supplying oil for lubrication, other components in the powertrain may need to be cooled by the oil. Instead of a required high oil pressure for lubrication, an increased oil flow for cooling of these components is needed. Components that may be cooled by an oil flow are electrical machines, bearings and gears.
The document EP2667053 A2 shows a cooling arrangement for motor vehicle power train, provided with a cooling fluid circuit that is controlled such that conveyed fluid is supplied to as friction clutch or to an electric machine, if required.
The required oil flow for removing heat losses from an electric machine may be very high. Therefore, it may be difficult to design an oil system for both cooling and lubrication with same oil circuit. Using an increased oil flow for cooling may lead to that bearings and gears may be lubricated by oil splash and oil bath by the same oil circuit. Instead, two separated and individually controlled oil systems may be used, each optimized for its special purpose. Such separated oil systems may however be negative for cost and maintenance reasons.
There is a need to further develop an oil distributor for a lubricating and cooling system in a powertrain which independently may optimize the cooling and lubrication with their required parameters for enabling high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components.
The object of the invention is therefore to develop an oil distributor for a lubricating and cooling system in a powertrain which independently may optimize the cooling- and lubrication with their required parameters for enabling high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components.
The herein mentioned object may be achieved by the above-mentioned oil distributor for a lubricating and cooling system in a powertrain according to the appending claims.
According to the invention the oil distributor may comprise a housing provided with at least one first oil inlet and at least two oil outlets. A first oil outlet may be connected to a first oil chamber and a second oil outlet may be connected to a second oil chamber. A piston may be arranged in a cavity of the housing. A piston may be movable between a first and a second position. The first oil outlet may be adapted to be connected to a first oil circuit. The second oil outlet may be adapted to be connected to a second oil circuit. The piston may comprise a first bore directed in a longitudinal direction of the piston. The second oil chamber may be at least in part constituted by the first bore in the piston. The piston may comprise a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position the at least one first oil inlet may be connected to the first oil chamber and the first oil outlet, and when the piston is in the second position the at least one first oil inlet may be connected to the second oil chamber and the second oil outlet.
The oil distributor may supply oil in two different circuits. Each circuit can be optimized for its purpose such as to secure the cooling performance of an electrical machine and to secure the endurance of transmission components, such as bearings and gears. The movable piston may be an on demand piston which direct links together the at least one first oil inlet with one of the chambers. The piston may close one of the two chambers and as a result supplying an oil flow for cooling or supplying oil for lubrication. The movable piston may be a one way air cylinder provided with a spring return. Other actuating means may be a two way air cylinder or an electrical power means with high precision for setting the piston in an accurate position.
According to a further aspect of the invention the at least one first oil inlet and the at least two oil outlets may be so arranged in the housing of the oil distributor that the at least one first oil inlet may be connected to both the first and second oil chambers and thus to the first and second oil outlets when the piston is arranged in a position between the first and the second position.
The movable piston may connect the at least one first oil inlet with both chambers and both oil outlets simultaneously. The piston may leave a pre-defined flow for booth cooling and lubrication.
According to a further aspect of the invention a second oil inlet may be arranged in the housing of the oil distributor and a third bore may be arranged in the piston, which connects the first bore with an outer periphery of the piston, so that when the piston is in the first position the second oil inlet may be connected to the second oil chamber and the second oil outlet.
A second oil inlet may increase the oil flow and increase the possibility to accurately control the oil distributor and independently optimize the cooling and lubrication with their required parameters for enabling high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components.
According to a further aspect of the invention a bypass channel may be arranged between the first oil chamber and another position in the cavity of the housing, so that when the piston is in the second position the second oil inlet may be connected to the first oil chamber and the first oil outlet via the bypass channel.
The bypass channel may make it possible to connect the second oil inlet to the first oil chamber and the first oil outlet.
According to a further aspect of the invention a cut out may be arranged in the piston, so that when the piston is in the second position the second oil inlet may be connected to the bypass channel by means of the cut out in the piston.
The cut out in the piston may have an extension in the longitudinal direction of the piston which may be adapted to the size of an bypass opening at the another position in the cavity of the housing, so that the second oil inlet may be connected to the bypass channel through the bypass opening and by means of the cut out in the piston.
According to a further aspect of the invention the second oil inlet and the at least two oil outlets may be so arranged in the housing of the oil distributor that the second oil inlet may be connected to both the first and second oil chambers and thus to the first and second oil outlets when the piston is arranged in a position between the first and the second position.
The movable piston may connect the second oil inlet with both chambers and both oil outlets simultaneously. The piston may leave a pre-defined flow for booth cooling and lubrication.
According to the invention a lubricating and cooling system in a powertrain may comprise a first oil circuit for cooling a first powertrain component and a second oil circuit for cooling a second powertrain component. The system further may comprise the oil distributor.
Such lubricating and cooling system in a powertrain may independently optimize the cooling and lubrication with their required parameters for enabling high cool oil flow in the first oil circuit for cooling a first powertrain component, and pressured circulated oil in the second oil circuit for cooling a second powertrain component.
According to a further aspect of the invention the first powertrain component may be an electrical machine and the second powertrain component may be a gearbox.
An electrical machine may generate heat and must be cooled to a preferred working temperature in order to achieve an optimized function and durability. The gearbox may comprise bearings and gears which may be lubricated in order to achieve an optimized function and durability.
According to a further aspect of the invention an electrical controlled oil pump may be connected to the at least one first oil inlet.
The electrical oil pump may be used for supplying oil both to the first oil circuit for cooling the first powertrain component and to the second oil circuit for cooling the second powertrain component.
According to a further aspect of the invention a mechanical controlled oil pump may be connected to the second oil inlet.
The mechanical oil pump may be used for supplying oil both to the first oil circuit for cooling the first powertrain component and to the second oil circuit for cooling the second powertrain component.
The electrical oil pump may mainly be used for cooling and the mechanical pump may mainly be used for lubrication. With the oil distributor in place the cooling and lubrication circuits may independently be optimized with their required parameters which enables high cool oil flow to the electrical machine for high performance, and pressured circulated oil for a durable lubrication system for the components to be lubricated.
For some gearbox variants the shafts may have no defined rotation direction and in some driving modes the mechanical pump may be outside its operation field. In these driving modes it may be necessary to have an oil distributor to switch and guide oil from the electrical oil pump to lubrication positions. It is also energy efficient when there is a high oil flow from the mechanical pump, due to high rotation speed on rotating components in the gearbox, to switch and cool the electrical machine by oil flow supplied by the mechanical pump and lubricate the components in the transmission by oil supplied by the electric pump at lower energy consumption.
The oil distributor may also be necessary on powertrains without an internal combustion engine and when no gearbox may be needed and therefore no mechanical connected pump may be available. In these applications the electrical oil pump may supply both the cooling and lubrication circuits with oil. In order to ensure correct oil distribution an active controlled distributor with predefined oil flow split may be needed instead of being dependent on a pressure difference which may differ depending on operation mode and oil temperature.
According to the invention a method of controlling a lubricating and cooling system in a powertrain may comprise an oil distributor which may comprise a housing provided with at least one first oil inlet and at least two oil outlets. A first oil outlet may be connected to a first oil chamber. A second oil outlet may be connected to a second oil chamber. A piston may be arranged in a cavity of the housing, which piston may be movable between a first and a second position. The piston may comprise a first bore directed in a longitudinal direction of the piston, so that the second oil chamber may at least in part be constituted by the first bore in the piston. The piston may comprise a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position the at least one first oil inlet may be connected to the first oil chamber and the first oil outlet, and when the piston is in the second position the at least one first oil inlet may be connected to the second oil chamber and the second oil outlet. A first oil circuit for cooling a first powertrain component may be connected to the first oil outlet. A second oil circuit for lubricating a second powertrain component may be connected to the second oil outlet. The method may comprise the steps of: a) controlling the pressure and flow of oil to the at least one first oil inlet by means of an electrical controlled oil pump connected to the at least one first oil inlet; and b) controlling the position of the piston in order to control the pressure and flow of oil through the first oil outlet and into the first oil circuit for cooling the first powertrain component and in order to control the pressure and flow of oil through the second oil outlet and into the second oil circuit for lubricating the second powertrain component.
Controlling of the pressure and flow of oil may be achieved by controlling the power to the electrical controlled oil pump. By also controlling the position of the piston in order to control the pressure and flow of oil, a high cool oil flow for heat generating components, and pressured circulated oil for transmission components may optimized independently.
According to a further aspect of the invention the method may comprise the further steps of: c) controlling the pressure and flow of oil to a second oil inlet by means of a mechanical controlled oil pump connected to the second oil inlet; and d) controlling the position of the piston in order to control the pressure and flow of oil through the first oil outlet and into the first oil circuit for cooling the first powertrain component and/or in order to control the pressure and flow of oil through the second oil outlet and into the second oil circuit for lubricating the second powertrain component.
Controlling of the pressure and flow of oil may be achieved by controlling the driving conditions of the transmission connected to the mechanical controlled oil pump. By also controlling the position of the piston in order to control the pressure and flow of oil a high cool oil flow for heat generating components, and pressurized circulated oil for transmission components may optimized independently.
According to a further aspect of the invention the method may comprise the further step of: e) cooling the oil in the first oil circuit by means of an oil cooler.
According to a further aspect of the invention the first powertrain component may be an electrical machine and the second powertrain component may be a gearbox.
An electrical machine generates heat and therefore may be cooled to a preferred working temperature in order to achieve an optimized function and durability. When cooling the electrical machine the heat electrical machine may be transferred to the oil. For this reason the oil in the first oil circuit may be cooled by means of an oil cooler.
Additional objectives, advantages and novel features of the invention will be apparent to one skilled in the art from the following details, and through exercising the invention. While the invention is described below, it should be apparent that the invention may be not limited to the specifically described details. One skilled in the art, having access to the teachings herein, will recognize additional applications, modifications and incorporations in other areas, which are within the scope of the invention.
Below is a description of, as examples, preferred embodiments with reference to the enclosed drawings, in which:
The movable piston 34 may in the intermediate position connect the at least one first oil inlet 22 with both chambers 30, 32 and both oil outlets 26, 28 simultaneously. The piston 34 may be an on demand piston 34 which direct links together the at least one first oil inlet 22 with one of the chambers 30, 32. The piston 34 may close one of the two chambers 30, 32 and as a result supplying an oil flow for cooling or supplying oil for lubrication. The movable piston 34 may be a one way air cylinder provided with a spring 48 for returning the piston 34 to the first and the intermediate position. Other actuating means 44 may be a two way air cylinder or an electrical power means with high precision that may set the piston 34 in an accurate position.
An electrical controlled oil pump 72 may be connected to the at least one first oil inlet 22. The electrical oil pump 72 may be used for supplying oil both to the first oil circuit 62 for cooling the first powertrain component such as the electrical machine 12 and to the second oil circuit 64 for cooling the second powertrain component such as bearings 18 and gears 16 in the gearbox 6. A mechanical controlled oil pump 74 may be connected to the second oil inlet 24. The mechanical oil pump 74 may be used for supplying oil both to the first oil circuit 62 for cooling the first powertrain component 12 and to the second oil circuit 64 for cooling the second powertrain component 16, 18. Oil is collected in a container 76 and circulated in the circuits 62, 64 by means of the pumps 72, 74. Oil is returned to the container 76 by means of a return channel 78.
The electrical oil pump 72 may mainly be used for cooling and the mechanical oil pump 74 may mainly be used for lubrication. With the oil distributor 2 in place the first and second circuits 62, 64 may independently be optimized with their required parameters, which enable high cool oil flow to the electrical machine 12 for high performance, and pressured circulated oil for a durable lubrication system for components to be lubricated.
For some gearbox variants shafts in the gearbox 6 have no defined rotation direction and in some driving modes the mechanical oil pump 74 may be outside its operation field. In these operation modes it may be necessary to have an oil distributor 2 to switch and guide oil from the electrical oil pump 72 to lubrication positions. It is also energy efficient when there is a high oil flow from the mechanical oil pump 74, due to high rotation speed on rotating components in the gearbox 6, to switch and cool the electrical machine 12 by oil flow supplied by the mechanical oil pump 74 and lubricate the components in the powertrain 14 by oil supplied by the electric oil pump 72 at lower energy consumption. Downstream the electrical oil pump 72 a first check valve 77 may be arranged in order to stop an oil flow in the direction towards the electrical oil pump 72. Downstream the mechanical oil pump 74 a second check valve 79 may be arranged in order to stop an oil flow in the direction towards the mechanical oil pump 72.
The oil distributor 2 may also be used on powertrains 14 without an internal combustion engine 4 and when no gearbox 6 may be needed and therefore no mechanical connected oil pump 74 may be available. In these applications the electrical oil pump 72 may supply both the first and second oil circuits 62, 64 with oil. To ensure correct oil distribution the oil distributor 2 with predefined oil flow split may be needed instead of being dependent on a pressure difference which may differ depending on operation mode and oil temperature.
Such lubricating and cooling system 60 in a powertrain 14 may independently optimize the cooling- and lubrication with their required parameters for enabling high cool oil flow in the first oil circuit 62 for cooling the first powertrain component 12, and pressured circulated oil in the second oil circuit 64 for lubricating the second powertrain component 16, 18.
A control unit 80 may be connected to the actuating means 44 for controlling the piston 34 position and thus controlling the distribution of oil to the first and second oil circuits 62, 64. The position sensor 37 may be connected to the control unit 80 for receiving information about the position of the piston 34 in the oil distributor 2. The control unit 80 may also be connected to the pumps 72, 74. The oil flow of the electrical pump 72 may be controlled by the control unit 80 and may be related to the temperature of the electrical machine 12 and the operation mode of the vehicle 1. The thermostat 68 may be electric or mechanic. The thermostat 68 may be connected to the control unit 80 and be controlled in relation to the oil temperature. The electrical machine 12 may be connected to the control unit 80 for sensing the temperature of the electrical machine 12. A temperature sensor 82 arranged at the oil container 76 may be connected to the control unit 80 for sensing the temperature of the oil.
The control unit 80 may comprise a computer 84, or a link to a computer 84, comprising a computer program P with programme code for receiving the data containing the current temperature of the oil and the electrical machine 12 in order to calculate the suitable position of the piston 34. The program code may be executed in the computer 84. The control unit 80 may further comprise stored data in a memory M, or a link to readable data, containing oil flow and oil pressure parameters for the first and second oil circuits 62, 64 and for different vehicle operation modes to control the position of the piston 34 and to control the oil flow and oil pressure from the pumps 72, 74. A computer program product may comprise a computer-readable medium and the computer program, which computer program may be contained in said computer-readable medium.
The method may comprise the steps of:
a) controlling the pressure and flow of oil to the at least one first oil inlet 22 by means of an electrical controlled oil pump 72 connected to the at least one first oil inlet 22; and
b) controlling the position of the piston 34 in order to control the pressure and flow of oil through the first oil outlet 26 and into the first oil circuit 62 for cooling the first powertrain 14 component and in order to control the pressure and flow of oil through the second oil outlet 28 and into the second oil circuit 64 for lubricating the second powertrain component 16, 18.
Controlling of the pressure and flow of oil may be achieved by controlling the power to the electrical controlled oil pump 72. By also controlling the position of the piston 34 in order to control the pressure and flow of oil, a high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components may be optimized independently.
The method may comprise the further steps of:
c) controlling the pressure and flow of oil to a second oil inlet 24 by means of a mechanical controlled oil pump 74 connected to the second oil inlet 24; and
d) controlling the position of the piston 34 in order to control the pressure and flow of oil through the first oil outlet 26 and into the first oil circuit 62 for cooling the first powertrain component 12 and/or in order to control the pressure and flow of oil through the second oil outlet 28 and into the second oil circuit 64 for lubricating the second powertrain component 16, 18.
Controlling of the pressure and flow of oil may be achieved by controlling the driving conditions of the transmission connected to the mechanical controlled oil pump 74. By also controlling the position of the piston 34 in order to control the pressure and flow of oil, a high cool oil flow for heat generating components, and pressurized circulated oil for transmission components may be optimized independently.
The method may comprise the further step of:
e) cooling the oil in the first oil circuit 62 by means of an oil cooler 66.
The first powertrain component may be an electrical machine 12. An electrical machine 12 generates heat and must be cooled to a preferred working temperature in order to achieve an optimized function and durability. When cooling the electrical machine 12 the heat generated by the electrical machine 12 may be transferred to the oil. For this reason the oil in the first oil circuit 62 may be cooled by means of an oil cooler 66.
The computer program comprising program code that, when said program code is executed in the computer 84, causes said computer 84 to carry out the above-mentioned method. The computer program product comprising the computer-readable medium and the computer program, which computer program is contained in said computer-readable medium.
The fluid for cooling and lubrication is described as oil. However, any oil or fluid that has cooling and lubrication properties may be used.
The foregoing description of the preferred embodiments has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate principles and practical applications, and to thereby enable one skilled in the art to understand the embodiments in terms of its various embodiments and with the various modifications that are applicable to its intended use. The components and features specified above may, within the framework of the embodiments, be combined between different embodiments specified.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1750895-3 | Jul 2017 | SE | national |
This application is a national stage application (filed under 35 § U.S.C. 371) of PCT/SE2018/050571, filed Jun. 4, 2018 of the same title, which, in turn, claims priority to Swedish Application No. 1750895-3 filed Jul. 7, 2017; the contents of each of which are hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2018/050571 | 6/4/2018 | WO | 00 |
