SE542029C2

SE542029C2 - A system and a method for controlling cooling of a combustion engine

Info

Publication number: SE542029C2
Application number: SE1650400A
Authority: SE
Inventors: Joakim Sommansson; Viktor Haak
Original assignee: Scania Cv Ab
Priority date: 2016-03-29
Filing date: 2016-03-29
Publication date: 2020-02-11
Also published as: SE1650400A1; DE102017002729A1

Abstract

The invention relates to a method for controlling cooling of a piston of at least one cylinder (250) of a combustion engine, comprising the steps of:- providing a cooling medium under pressure to a crankcase side of said cylinder (250) via a first valve arrangement (240) comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement (241, 242) for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet; and- providing said cooling medium to a second valve arrangement (220) for providing cooling medium to said spring loaded piston arrangement (241, 242) for controlling said predetermined cooling medium pressureThe invention relates also to a computer programme product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention relates also to a system for controlling cooling of a piston of at least one cylinder (250) of a combustion engine and a motor vehicle (100) equipped with the system.

Description

A system and a method for controlling cooling of a combustion engine TECHNICAL FIELD The present invention relates to a method for controlling cooling of a combustion engine. More particularly, the present invention relates to a method for controlling cooling of a piston of at least one cylinder of a combustion engine. The invention relates also to a computer program product comprising program code for a computer for implementing a method according to the invention. It relates also to a system for controlling cooling of a piston of at least one cylinder of a combustion engine and a motor vehicle equipped with the system.

BACKGROUND ART Sufficient and adequate cooling of a piston of at least one cylinder of a combustion engine is important for proper operation. Said combustion engine may for example be arranged for generating torque for propelling a vehicle, such as a heavy vehicle.

Today so called piston cooling is used by injecting a cooling medium to a crankcase side of an engine cylinder which is housing a piston. The cooling medium is provided to said cylinder via a valve arrangement by means of a pump arrangement. Said cooling medium may comprise cooling oil. Said crankcase side of said cylinder is located opposite of a combustion chamber of said cylinder. In this way cooling is provided to said piston of said cylinder of said combustion engine. The cooling medium is hereby circulated in a closed loop via a cooling medium storage container, said pump, the various cylinders of the combustion engine and back to the container.

Said valve arrangement is provided with a spring loaded pipe piston, which is designed to open at a predetermined cooling medium pressure provided by said pump arrangement. This predetermined cooling medium pressure may be any suitable pressure, such as 2 bar. If the cooling medium pressure provided by said pump arrangement is below said predetermined cooling medium pressure the valve arrangement is set to a closed state and piston cooling of said cylinder(s) is shut off. In a similar way, if the cooling medium pressure provided by said pump arrangement is above said predetermined cooling medium pressure the valve arrangement is set to an open state and piston cooling of said cylinder(s) is provided.

Even if this depicted solution may work satisfactory at some engine operation states it is also associated with a number of drawbacks.

At some operational states of the combustion engine, where the cooling medium pressure is exceeding said predetermined cooling medium pressure, continuous cooling of the respective pistons of the cylinders of the engine is provided. This is not always desired and hereby cooling may be performed even though a relatively high operational temperature of the combustion engine would be more optimal for various reasons.

At some other operational states of the combustion engine, e.g. involving relatively low loads, cooling of a piston of at least one cylinder of the combustion engine to a too large extent may be provided, which may result in that unnecessary fuel consumption for increasing the temperature of the engine at a later stage is required.

EP1929130 relates to a valve configuration allowing provision of a cooling medium at relatively low engine speeds by proving one inlet and two outlets for said cooling medium.

SUMMARY OF THE INVENTION There is a need for an improved piston cooling system wherein said drawbacks may be eliminated or reduced.

An object of the present invention is to propose a novel and advantageous method for controlling cooling of a piston of at least one cylinder of a combustion engine.

Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program for controlling cooling of a piston of at least one cylinder of a combustion engine.

Another object of the present invention is to propose a novel and advantageous method providing a reliable, adequate and desired cooling of a piston of at least one cylinder of a combustion engine at various operational states of said combustion engine.

Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program providing sufficient cooling of a piston of at least one cylinder of a combustion engine also at relatively low cooling medium pressures.

Yet another object of the invention is to propose a method, a system and a computer program achieving a fuel consumption efficient cooling of a piston of at least one cylinder of a combustion engine.

Yet another object of the invention is to propose an alternative method, an alternative system and an alternative computer program for controlling cooling of a piston of at least one cylinder of a combustion engine.

Some of these objects are achieved with a method according to claim 1. Other objects are achieved with a system in accordance with what is depicted herein. Advantageous embodiments are depicted in the dependent claims. Substantially the same advantages of method steps of the innovative method hold true for corresponding means of the innovative system.

According to an aspect of the invention there is provided a method for controlling cooling of a piston of at least one cylinder of a combustion engine.

The method comprises the step of providing a cooling medium under pressure to a crankcase side of said cylinder via a first valve arrangement comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet.

The method comprises the step of providing said cooling medium to a second valve arrangement for providing cooling medium to said spring loaded piston arrangement for controlling said predetermined cooling medium pressure.

The method comprises the step of providing in said spring loaded piston arrangement an additional spring loaded piston for providing a certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure. Hereby sufficient cooling may be provided even at cooling medium pressures entailing the main piston of said first valve configuration to shut off a main cooling medium flow.

By controlling said second valve arrangement, e.g. electrically or electronically, said predetermined cooling medium pressure may be controlled efficiently and reliably. Hereby a pressure balance may be created at said first valve arrangement. Said second valve arrangement may be controlled by means of an electronic control unit.

Hereby cooling of said piston of at least one cylinder may be interrupted even though the cooling medium pressure at the inlet of said first valve arrangement is above a pressure corresponding to the acting force of the spring loading said piston arrangement.

Hereby a versatile, robust and reliable cooling method is advantageously provided.

Advantageously the proposed method is applicable to various combustion engines, e.g. diesel engines or Otto-engines. The proposed method is thus versatile.

The method may comprise the step of controlling said second valve arrangement for controlling said spring loaded piston arrangement to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement.

Hereby suitable cooling may be provided paying regard to a current operation state of said combustion engine. Hereby suitable cooling may be provided paying regard to a future predicted operation state of said combustion engine. Hereby electronic maps and/or lookahead information may be used for adequate control of said second valve arrangement. According to one embodiment certain parameters, such as a prevailing cooling medium temperature may be used for adequate control of said second valve arrangement. Said second valve arrangement may be controlled by means of an ECU, such as an electronic engine control unit. Said electronic maps and look-ahead information may be stored in a memory of said ECU.

The method may comprise the step of controlling said second valve arrangement to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement and a de-activated state wherein cooling medium is drained from said spring loaded piston arrangement.

Hereby reliable control of said second valve arrangement is provided. By only switching between said activated state and said de-activated state short response times are provided regarding continuous adjustments of said predetermined cooling medium pressure. Hereby accurate cooling control is provided. The proposed method is further cost effective to implement since only rather cheap components are required to be installed in existing cooling systems/vehicle cooling systems for proper cooling control.

According to an aspect of the invention there is provided a system for controlling cooling of a piston of at least one cylinder of a combustion engine.

The system comprises means being arranged for providing a cooling medium under pressure to a crankcase side of said cylinder via a first valve arrangement comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet.

The system comprises means being arranged for providing said cooling medium to a second valve arrangement for providing cooling medium to said spring loaded piston arrangement for controlling said predetermined cooling medium pressure.

The system comprises an additional spring loaded piston for providing a certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure, which additional spring loaded piston is provided in said spring loaded piston arrangement.

The system may comprise means being arranged for controlling said second valve arrangement for controlling said spring loaded piston arrangement to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement.

The system may comprise means being arranged for controlling said second valve arrangement to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement and a de-activated state wherein cooling medium is drained from said spring loaded piston arrangement.

Said second valve arrangement may comprise a so called 3/2 valve configured with a solenoid actuation.

According to an aspect of the invention there is provided a vehicle comprising a system according to what is presented herein. Said vehicle may be any from among a truck, bus or passenger car. According to an embodiment the system is provided for a marine application or industrial application.

According to an aspect of the invention there is provided a computer program for controlling cooling of a piston of at least one cylinder of a combustion engine, wherein said computer program comprises program code for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program for controlling cooling of a piston of at least one cylinder of a combustion engine, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein.

According to an aspect of the invention there is provided a computer program for controlling cooling of a piston of at least one cylinder of a combustion engine, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform anyone of the method steps depicted herein, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program product containing a program code stored on a computer-readable medium for performing anyone of the method steps depicted herein, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

According to an aspect of the invention there is provided a computer program product containing a program code stored non-volatile on a computer-readable medium for performing anyone of the method steps depicted herein, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details, and also by putting the invention into practice. Whereas the invention is described below, it should be noted that it is not confined to the specific details described. One skilled in the art having access to the teachings herein will recognise further applications, modifications and incorporations in other fields, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS For fuller understanding of the present invention and its further objects and advantages, the detailed description set out below should be read in conjunction with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which: Figure 1 schematically illustrates a vehicle according to an embodiment of the invention; Figure 2a schematically illustrates a cooling system according to an embodiment of the invention; Figure 2b schematically illustrates a cooling system according to an embodiment of the invention; Figure 2c schematically illustrates a cooling system according to an embodiment of the invention; Figure 2d schematically illustrates a cooling system according to an embodiment of the invention; Figure 3a is a schematic flowchart of a method according to an embodiment of the invention; Figure 3b is a more detailed schematic flowchart of a method according to an embodiment of the invention; and Figure 4 schematically illustrates a computer according to an embodiment of the invention.

DETAILED DESCRIPTION Figure 1 depicts a side view of a vehicle 100. The exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112. The vehicle 100 may be a heavy vehicle, e.g. a truck or a bus. It may alternatively be a car.

It should be noted that the inventive system is applicable to various vehicles, such as e.g. a mining machine, tractor, dumper, wheel loader, platform comprising an industrial robot, forest machine, earth mover, road construction vehicle, road planner, emergency vehicle or a tracked vehicle.

It should be noted that the invention is suitable for application in various systems comprising a diesel engine or an Otto-engine. It should be noted that the invention is suitable for application with any combustion engine having at least one cylinder and is therefore not confined to combustion engines of motor vehicles. The innovative method and the innovative system in one aspect of the invention are well suited to other platforms which comprise a combustion engine system than motor vehicles, e.g. watercraft. The watercraft may be of any kind, e.g. motor boats, steamers, ferries or ships.

The innovative method and the innovative system according to one aspect of the invention are also well suited to, for example, systems which comprise industrial engines and/or enginepowered industrial robots.

The innovative method and the innovative system according to one aspect of the invention are also well suited to various kinds of power plants, e.g. an electric power plant which comprises an engine-powered generator.

The innovative method and the innovative system are also well suited to various combustion engine systems, e.g. on a locomotive or some other platform.

The term "link" refers herein to a communication link which may be a physical connection such as an opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.

With reference to Figure 2a there is illustrated a cooling system 299. The cooling system may be provided in said vehicle 100.

A first control unit 200 is arranged for communication with a second valve arrangement 220 via a link L220. Said first control unit is arranged to control said second valve arrangement 220 by means of command signals S220 comprising information about which state said second valve arrangement should be in, namely an open, activated state or a closed, deactivated state. Alternatively, said second valve arrangement 220 may be controlled electrically by means of said first control unit 200 via any suitable wire configuration.

Said second valve arrangement 220 may be any suitable valve arrangement allowing, where applicable, provision of a cooling medium to a first valve configuration 240 via a first passage P240. Said second valve arrangement 220 may comprise an electronically or electrically controlled 3/2 valve. It should be noted that said second valve arrangement 220 may comprise any suitable actuator.

A pump configuration 230 is arranged to extract cooling medium from a cooling medium container via a second passage P260b. Said pump configuration 230 is arranged to provide said cooling medium to said first valve arrangement 240 via a third passage P230b. Said pump configuration 230 is arranged to provide said cooling medium to said second valve arrangement 220 via a fourth passage P230a.

Said first valve configuration 240, being in an open state, is arranged to provide said cooling medium to at least one cylinder 250 of a combustion engine via a fifth passage P250. Said provision of said cooling medium at said cylinder 250 is herein denoted piston cooling.

Hereby a piston of said cylinder 250 is cooled by said provided cooling medium at a crankcase side of said cylinder 250. Said provided cooling medium is returned to said cooling medium container 260 by any suitable means, such as a passage configuration comprising one or more pipes.

Cooling medium being provided to said second valve arrangement 220 (and potentially to said first valve arrangement 240) is returned to said cooling medium container 260 via a sixth passage P260a.

A second control unit 210 is arranged for communication with the first control unit 200 via a link L210. It may be releasably connected to the first control unit 200. It may be a control unit external to the vehicle 100. It may be adapted to performing the innovative steps according to the invention. It may be used to cross-load software to the first control unit 200, particularly software for applying the innovative method. It may alternatively be arranged for communication with the first control unit 200 via an internal network on board the vehicle. It may be adapted to performing functions corresponding to those of the first control unit 200, such as controlling provision of said cooling medium to said second valve arrangement 220 for providing cooling medium to said spring loaded piston arrangement of said first valve arrangement 240.

Figure 2b schematically illustrates in greater detail a cooling system 299 of the vehicle 100 shown in Figure 1 and Figure 2a, according to an aspect of the invention.

The first valve arrangement 240 comprises an inlet, which is associated with said third passage P230b. The first valve arrangement 240 comprises an outlet, which is associated with said fifth passage P250. The first valve arrangement 240 comprises a spring 242 biasing a piston 241. Said spring 242 provides a predetermined suitable spring force.

The second valve arrangement 220 is arranged to provide pressurized cooling medium to a closed chamber of said first valve arrangement 240. Said pressurized cooling medium provided to the first valve arrangement 240 hereby acts on the piston 241 in the same direction as said spring 242. This means that if no pressurized cooling medium is provided to the first valve arrangement 240 only the spring force of said spring 242 is acting on said piston 241. This is schematically illustrated in Figure 2b. In this case a pressure of said cooling medium at said inlet is lower than a pressure induced by means of said spring 242. Hereby said first valve arrangement 240 is in a closed position and no cooling medium is provided to said outlet for provision to said cylinder 250 via said fifth passage P250.

A similar state of the first valve arrangement 240 may alternatively be achieved by pressurizing said piston 241 by means of cooling medium provided by said second valve arrangement 220 in a case where the cooling medium pressure in the third passage P230b is higher than a pressure associated with the spring force of the spring 242. This will allow the cooling of the piston of the cylinder 250 to be turned off even if the pressure of the cooling medium in the third passage P230b is greater than the spring force of the spring 242.

Figure 2c schematically illustrates a cooling system 299 of the vehicle 100 shown in Figure 1, according to an aspect of the invention.

According to an embodiment said piston 241 comprises a spring loaded piston arrangement 243. Hereby said piston 241 comprises an inlet (not shown) and an outlet (not shown). The spring loaded piston arrangement 243 is arranged to allow a certain flow between said inlet and said outlet, i.e. between said third passage P230b and said fifth passage P250, even if the piston 241 is in a position of shutting off a main flow of cooling medium between said third passage P230b and said fifth passage P250, and if a pressure of the cooling medium in said third passage P230b exceeds the pressure associated with the spring force of said spring loaded piston arrangement 243. By providing this additional valve configuration (housed in said piston 241) a certain flow of said cooling medium may be provided from said inlet to said outlet and further to said fifth passage P250 even if said piston 241 is in a state of blocking a main flow to said passage fifth P250. That is, if a pressure of said cooling medium is greater than a pressure induced by said additional spring being provided in said piston 241. This advantageously may provide a certain flow of cooling medium for cooling said piston of said cylinder 250 at a state where said piston 241 is blocking a main flow to said fifth passage P250. In case said piston 241 is suffering a mechanical failure said additional spring loaded piston of said piston 241 may provide a certain flow of cooling medium through said first valve arrangement 240 for securing sufficient cooling of said at least one cylinder 250. Said certain flow of cooling medium is typically less than a main flow at a state where said first valve arrangement is in a closed position (regarding said piston 241).

Figure 2c is schematically illustrating a state where said piston 241 is causing the main flow of said cooling medium to be interrupted, but where a certain flow of cooling medium is provided to said fifth passage P250 by means of said spring biased piston 243 arranged within said piston 241. Herein said second valve arrangement 220 may, or may not (depending upon the prevailing pressure of said cooling medium at said inlet of said first valve arrangement 240), have supplied pressurized cooling medium to said first valve arrangement 240.

Figure 2d schematically illustrates a cooling system 299 of the vehicle 100 shown in Figure 1, according to an aspect of the invention.

According to this presented state of the first valve arrangement 240 the piston 241 is fully pressed back by the pressure of the cooling medium at said inlet of said first valve arrangement 240. Hereby a main flow of said cooling medium is provided to said fifth passage P250 from said pressurized inlet.

Hereby said closed chamber for holding provided cooling medium at said piston 241 is drained of cooling medium, thus providing no additional force acting on said piston 241. Only said spring force of said spring 242 is acting on said piston 241, but said pressure of said cooling medium at said inlet is supressing said piston 241 to an open state of said first valve arrangement 240.

Figure 3a schematically illustrates a flow chart of a method for controlling cooling of a piston of at least one cylinder 250 of a combustion engine. The method comprises a first method step s301. The method step s301 comprises the steps of: - providing a cooling medium under pressure to a crankcase side of said cylinder 250 via a first valve arrangement 240 comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement 241 for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet, and - providing said cooling medium to a second valve arrangement 220 for providing cooling medium to said spring loaded piston arrangement 241 for controlling said predetermined cooling medium pressure.

After the method step s301 the method ends/is returned.

Figure 3b schematically illustrates a flow chart of a method for controlling cooling of a piston of at least one cylinder 250 of a combustion engine. The method comprises a first method step s310.

The method step s310 comprises the step of pumping cooling medium from a cooling medium container 260 to the first valve arrangement 240 and the second valve arrangement 220. Hereby pressurized cooling medium is provided for piston cooling of the at least one cylinder 250 of the combustion engine.

After the step s310 a subsequent step s320 is performed.

The method step s320 comprises the step of determining cooling control data. Said cooling control data may relate to electronic map information, look-ahead information, operational states of the combustion engine, operational states of any other system of the vehicle 100, and/or prevailing states of any relevant component/device/system of said vehicle 100, such as a prevailing temperature of said cooling medium, e.g. in said cooling medium container 260. Said cooling control data may be determined by means of any suitable means, such as sensors or electronic control units. Said cooling control data may comprise any information relevant for determining an adequate need for cooling said pistons of the various cylinders of said combustion engine. Said cooling control data may be used as a basis for controlling cooling of said combustion engine according to an embodiment of the invention.

After the method step s320 a subsequent method step s330 is performed.

The method step s330 comprises the step of controlling cooling of a piston of the at least one cylinder 250 of the combustion engine. Hereby it may be determined a suitable cooling on the basis of said determined cooling control data. Hereby said second valve arrangement 220 is controlled by means of said first control unit 200 so as to control a prevailing total force acting on the piston 241 of the first valve arrangement 240.

By supplying cooling medium to said chamber of the first valve arrangement 240 from said second valve arrangement 220 said total force may be increased. This means that a predetermined cooling medium pressure required for opening said first valve arrangement 240 is controlled, i.e. is increased. Hereby said second valve arrangement 220 for controlling said spring loaded piston arrangement 241, 242 is controlled to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement 241, 242. Hereby said second valve arrangement 220 is controlled to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement 241, 242.

By draining cooling medium from said chamber of the first valve arrangement 240 via said second valve arrangement 220 said total force may be decreased. This means that a predetermined cooling medium pressure required for opening said first valve arrangement 240 is controlled, i.e. is decreased. Hereby said second valve arrangement 220 for controlling said spring loaded piston arrangement 241, 242 is controlled to reduce a prevailing cooling medium pressure in addition to the spring load of said spring loaded piston arrangement 241, 242. Hereby controlling said second valve arrangement 220 is controlled to provide a de-activated state wherein cooling medium is drained from said spring loaded piston arrangement 241, 242.

The step s330 may comprise the step of providing a certain cooling medium flow from said inlet to said outlet of said first valve arrangement 240 at a state of said first valve arrangement 240 wherein said piston 241 is in a position where a main flow from said inlet to said outlet of said first valve arrangement 240 is prevented. This is performed by means of said additional spring loaded piston 243 for providing a certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure.

After the method step s330 the method ends/is returned.

Figure 4 is a diagram of one version of a device 500. The control units 200 and 210 described with reference to Figure 2 may in one version comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540.

The computer program P comprises routines for controlling cooling of a piston of at least one cylinder 250 of a combustion engine.

The computer program P may comprise routines for controlling provision of a cooling medium under pressure to a crankcase side of said cylinder 250 via a first valve arrangement 240 comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement 241, 242 for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet.

Alternatively this provision of said cooling medium under pressure may be performed mechanically.

The computer program P may comprise routines for controlling provision of said cooling medium to a second valve arrangement 220 for providing cooling medium to said spring loaded piston arrangement 241, 242 for controlling said predetermined cooling medium pressure.

The computer program P may comprise routines for controlling said second valve arrangement 220 for controlling said spring loaded piston arrangement 241, 242 to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement 241, 242.

The computer program P may comprise routines for controlling said second valve arrangement 220 to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement 241, 242 and a de-activated state wherein cooling medium is drained from said spring loaded piston arrangement 241, 242.

The computer program P may comprise routines for controlling provision of certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure. Hereby an additional spring loaded piston 243 for providing a certain cooling medium flow is provided in said spring loaded piston arrangement 241, 242.

The program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550.

Where it is stated that the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit via a data bus 511. The read/write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514. The links L210 and L220, for example, may be connected to the data port 599 (see Figure 2a, Figure 2b, Figure 2c and Figure 2d).

When data are received on the data port 599, they are stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 will be prepared to conduct code execution as described above.

Parts of the methods herein described may be conducted by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.

The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the variants described. Many modifications and variations will obviously suggest themselves to one skilled in the art. The embodiments have been chosen and described in order to best explain the principles of the invention and their practical applications and thereby make it possible for one skilled in the art to understand the invention for different embodiments and with the various modifications appropriate to the intended use.

Claims

1. A method for controlling cooling of a piston of at least one cylinder (250) of a combustion engine, comprising the step of: - providing a cooling medium under pressure to a crankcase side of said cylinder (250) via a first valve arrangement (240) comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement (241, 242) for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet, characterized in the step of: - providing said cooling medium to a second valve arrangement (220) for providing cooling medium to said spring loaded piston arrangement (241, 242) for controlling said predetermined cooling medium pressure, and - providing in said spring loaded piston arrangement (241, 242) an additional spring loaded piston (243) for providing a certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure.

2. The method according to claim 1, comprising the step of: - controlling said second valve arrangement (220) for controlling said spring loaded piston arrangement (241, 242) to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement (241, 242).

3. The method according to claim 2, comprising the step of: - controlling said second valve arrangement (220) to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement (241, 242) and a deactivated state wherein cooling medium is drained from said spring loaded piston arrangement (241, 242).

4.. A system for controlling cooling of a piston of at least one cylinder (250) of a combustion engine, comprising: - means (260, 240, P250) arranged for providing a cooling medium under pressure to a crankcase side of said cylinder (250) via a first valve arrangement (240) comprising a cooling medium inlet and a cooling medium outlet and a spring loaded piston arrangement (241, 242) for flow connection between said cooling medium inlet and said cooling medium outlet at a predetermined cooling medium pressure at said inlet, characterized by: - means (260, 200, 210, 500, P240) arranged for providing said cooling medium to a second valve arrangement (220) for providing cooling medium to said spring loaded piston arrangement (241, 242) for controlling said predetermined cooling medium pressure, and - an additional spring loaded piston (243) for providing a certain cooling medium flow from said inlet to said outlet at a cooling medium pressure at said inlet below said predetermined cooling medium pressure, which additional spring loaded piston (243) is provided in said spring loaded piston arrangement (241, 242).

5. The system according to claim 4, comprising: - means (200, 210, 500) arranged for controlling said second valve arrangement (220) for controlling said spring loaded piston arrangement (241, 242) to provide a certain cooling medium pressure in addition to the spring load of said spring loaded piston arrangement (241, 242).

6. The system according to claim 5, comprising: - means (200, 210, 500) arranged for controlling said second valve arrangement (220) to provide an activated state wherein cooling medium is fed to said spring loaded piston arrangement (241, 242) and a de-activated state wherein cooling medium is drained from said spring loaded piston arrangement (241, 242).

7. A vehicle (100; 110) comprising a system according to anyone of claims 4-6.

8. The vehicle (100; 110) according to claim 7, which vehicle is any from among a truck, bus or passenger car.

9. A computer program (P) for controlling cooling of at least one cylinder (250) of a combustion engine, wherein said computer program (P) comprises program code for causing an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500) to perform the steps according to any of the claims 1-3.

10. A computer program product containing a program code stored on a computer-readable medium for performing method steps according to any of claims 1-3, when said computer program is run on an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500).