GB2591272A

GB2591272A - Internal combustion engine for a vehicle

Info

Publication number: GB2591272A
Application number: GB2000993.2A
Authority: GB
Inventors: Hoffmann Michael; Lanier Gary; Winter Diethard; Raghuthaman Sachin; Sharma Nihal; Agarwala Bhubaneswar
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2020-01-23
Filing date: 2020-01-23
Publication date: 2021-07-28
Also published as: GB202000993D0

Abstract

An internal combustion engine 10 for a vehicle has two oil pumps that operate independently. The first oil pump 20 can pump oil from a reservoir 22 of the engine oil circuit 24 into a first oil supply conduit 18. The second oil pump 30 can pump oil from the engine oil circuit into a second oil supply conduit 26 which can supply oil to at least one piston cooling jet 28. The first pump can be a mechanical pump and the second pump can be an electric pump. Oil delivered by the second pump can be controlled by a valve 34 so that oil can be supplied into the first oil supply conduit and/or the second oil supply conduit. When there is a plurality of piston cooling jets, a multi-valve arrangement may allow individual control of the piston cooling jet to each piston. The piston cooling jet may be controlled by a control unit 58 according to engine temperature, engine speed, engine torque and/or power. Control of the piston cooling oil flow to a minimum requirement delivers better fuel efficiency for the engine.

Description

INTERNAL COMBUSTION ENGINE FOR A VEHICLE

FIELD OF THE INVENTION

[0001] The invention relates to an internal combustion engine for a vehicle, comprising a first oil supply conduit for supplying oil to at least one movable component of the engine, and a second oil supply conduit for supplying oil to at least one piston cooling jet. The at least one piston cooling jet is configured to cool at least one piston of the engine. The at least one piston is configured to move within a corresponding cylinder of a cylinder block of the engine.

BACKGROUND INFORMATION

[0002] Piston cooling jets are utilized in an internal combustion engine of a vehicle to spray oil on a surface of a piston for cooling purposes. The surface to which the oil is supplied by the cooling jets is usually opposite a further surface of the piston, wherein the further surface delimits a combustion chamber of the cylinder in which the piston moves during operation of the engine. The oil flow towards the piston cooling jets, or cooling nozzles, is one of the largest oil consumers within the internal combustion engine. By minimizing the oil flow towards the piston cooling jets, the power consumption of an oil pump can therefore be reduced. This leads to a better fuel efficiency of the combustion engine.

[0003] GB 2484748 A describes an internal combustion engine wherein an oil main gallery is provided for supplying oil to a bearing and a plurality of pistons of the combustion engine. By means of a conduit, the oil main gallery is in fluid communication with a separate piston jet gallery. Oil flowing through the separate piston jet gallery is delivered to a plurality of nozzles. Each nozzle sprays oil directed at the hottest part of a respective piston. Oil from the piston jet gallery is recirculated back to a reservoir of the combustion engine. The internal combustion engine comprises a valve for controlling the supply from the oil main gallery to the separate piston jet gallery.

[0004] However, in this internal combustion engine the oil pressure within the main oil gallery is used to supply oil for cooling the pistons. The activation of the piston cooling is controlled by operating the solenoid-actuated valve.

[0005] It is therefore necessary to maintain a comparatively high pressure within the oil main gallery in order to provide cooling to the pistons by means of the oil delivered through the separate piston jet gallery. This high pressure is directly dependent on the main oil pump supply. This goes along with a comparatively high power consumption of the oil pump, and consequently with an increased fuel consumption, if the piston cooling jets are supplied with oil for cooling purpose.

[0006] It is therefore an object of the present invention to provide an internal combustion engine of the initially mentioned kind, which is improved with respect to fuel efficiency.

[0007] This object is solved by an internal combustion engine having the features of claim 1. Advantageous configurations with further developments of the invention are specified in the dependent claims and in the following description.

SUMMARY OF THE INVENTION

[0008] The internal combustion engine according to the invention comprises a first oil supply conduit for supplying oil to at least one movable component of the engine, and a second oil supply conduit for supplying oil to at least one piston cooling jet. The at least one piston cooling jet is configured to cool at least one piston of the engine. The at least one piston is configured to move within a corresponding cylinder of a cylinder block of the engine. The engine comprises a first pump for pumping oil from a reservoir of an oil circuit of the engine into the first oil supply conduit. The engine further comprises a second pump for pumping oil from the oil circuit into the second oil supply conduit. Herein, the second pump is configured to be operated independently from the first pump.

[0009] Therefore, instead of drawing oil from the first oil supply conduit which can also be called a main oil gallery, the exclusive second oil pump supplies oil to the at least one piston cooling jet. Oil from this main oil gallery can in particular be utilized to provide oil under pressure to rotating bearings of the engine, to the sliding pistons of the engine, to a camshaft of the engine and the like movable components.

[0010] The second pump can be operated independently from the first pump in order to provide oil to the at least one piston for cooling purposes. Therefore, supplying oil to the at least one piston cooling jet does not require an increased pressure to be built up by the first pump. In other words the cooling of the at least one piston is achieved by other means than pumping oil through the first oil supply conduit or main oil gallery. In this way the oil supply for the at least one piston cooling jet is decupled from the main oil gallery or first oil supply conduit. By including the second pump for pumping oil into the second oil supply conduit the power consumption of the first pump can therefore be reduced and/or optimized. This improves the fuel efficiency of the internal combustion engine. Therefore, fuel economy can be achieved in operating the internal combustion engine.

[0011] By providing the second pump for pumping oil into the second oil supply conduit the oil supply to the at least one piston cooling jet is a separate architecture or secondary oil circuit which is independent of the first oil supply conduit or main oil gallery. In particular, by operating the second pump a pre-lubrication of the at least one piston can be achieved at the time of engine start. Such a pre-lubrication avoids an increased friction and therefore also contributes to the fuel efficiency of the internal combustion engine.

[0012] Preferably, the first pump is a mechanical pump which is operatively connected to a crankshaft of the engine, wherein the second pump is an electric pump. By configuring the second pump as an electric pump oil can be provided to the at least one piston, in particular prior to engine start, in a very simple manner.

[0013] Preferably, the engine comprises a valve element by means of which oil delivered by the second pump can be supplied into the first oil supply conduit and/or into the second oil supply conduit. By operating the valve element, it can therefore be controlled, whether oil which is pumped by the second pump shall be utilized for cooling the at least one piston or for other purposes in operating conditions which do not necessitate piston cooling. The second pump can for example be operated and the valve element controlled accordingly such that oil is supplied only into the first oil supply conduit. This can be beneficial to avoid an overheating of the engine in an operating state of the engine, in which there is no need for piston cooling by utilizing the at least one piston cooling jet. The valve element or oil control valve can therefore be operated in order to supply oil to the first oil supply conduit or main oil gallery based on specific engine requirements.

[0014] Preferably, the second oil supply conduit is embedded inside the cylinder block. This is advantageous as there is no need to create additional channels or to carry out any substantial change in oil channels already provided in a crankcase of the engine.

[0015] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings show in: [0017] Fig. 1 a schematic of components of an internal combustion engine having a separate oil supply conduit for supplying oil to piston cooling jets of the engine and an electric oil pump for pumping oil into the separate oil supply conduit; [0018] Fig. 2 a cylinder block of the engine according to Fig. 1, wherein the oil supply conduit is embedded inside the cylinder block; and [0019] Fig. 3 an exploded view of components of the oil supply conduit and the piston cooling jets before the integration of these components into the cylinder block of the engine.

[0020] In the figures the same elements or elements having the same function are indicated by the same reference signs.

DETAILED DESCRIPTION

[0021] Fig. 1 schematically shows components of an internal combustion engine 10 comprising a cylinder block 12, which is shown in more detail in Fig. 2. The cylinder block 12 comprises a plurality of cylinders 14, wherein only some of the cylinders 14 are provided with a reference sign in Fig. 2. Pistons 16 (which are schematically shown in Fig. 1) move up and down in the cylinders 14 during operation of the engine 10. For lubricating movable components of the engine 10, oil is provided to these movable components through a first oil supply conduit, or main oil gallery 18 (see Fig. 1). A first pump 20 or main pump is provided for pumping oil from a reservoir 22 of an oil circuit 24 of the engine 10 into the main oil gallery 18.

[0022] The internal combustion engine 10 further comprises a second oil supply conduit 26, which is configured as an oil supply pipe or oil supply rail (see Fig. 1). Through this second oil supply conduit 26, oil can be delivered to a plurality of piston cooling jets 28, wherein only some of the piston cooling jets 28 are provided with a reference sign in Fig. 1. Oil can be sprayed on the pistons 16 for cooling purposes by the piston cooling jets 28 or nozzles.

[0023] In the internal combustion engine 10 shown in Fig. 1, instead of drawing oil from the main oil gallery 18, an exclusive second oil pump, which is preferably configured as an electric pump 30, supplies oil to the piston cooling jets 28. The electric pump 30 can be operated independently from the first pump 20. Therefore, it is not necessary to build up a particularly high pressure by means of the first pump 20 in order to provide cooling oil to the piston cooling jets 28.

[0024] According to Fig. 1, an outlet pipe 32 into which oil pumped by the electric pump 30 is connected to a valve element in the form of an electric oil control valve 34. The control valve 34 can be operated in a manner in which oil pumped by the electric pump 30 is delivered to the oil supply conduit 26 through a first outlet of the control valve 34. A pipe connected to this first outlet is illustrated as an arrow 36 in Fig. 1.

[0025] Alternatively or additionally, the oil pumped by the electric pump 30 can be supplied into the main oil gallery 18 through a second outlet of the valve 34. A pipe connected to this second outlet is illustrated as a further arrow 38 in Fig. 1. Oil coming from the electric pump 30 can be supplied to the main oil gallery 18 when operating conditions do not necessitate piston cooling.

[0026] A single oil pipe or oil rail forming the oil supply conduit 26 shown in Fig. 1 is preferably embedded inside the engine block or cylinder block 12 shown in Fig. 2.

Therefore, each piston cooling jet 28 can be supplied with oil without the need for having separate channels to supply each one of the piston cooling jets 28.

[0027] The oil volume to supply the piston cooling jets 28 by operating the electric pump 30 can be taken from the main oil gallery 18 or from any other location of the engine's oil circuit 24. Such a location may include an oil sump (not shown) within an oil pan of the engine 10.

[0028] As can be seen from Fig. 2, the oil pipe or oil rail forming the oil supply conduit 26 is mounted inside the cylinder block 12 or engine block. The oil rail can be mounted from a rear side 40 of the cylinder block 12 or from a front side 42 of the cylinder block 12 (see Fig. 2). The rear side 40 is the side of the cylinder block 12 or engine block which faces a gear train (not shown).

[0029] The rear assembly option shown in Fig. 3 has the advantage that the cylinder block 12 does not need to be sealed by an additional component specifically provided for this purpose only. This is because in the rear assembly an insertion area 44 (see Fig. 3) of the cylinder block 12 is open to the gear train area of the engine 10. This area is a low pressure oil flow area or low pressure oil drain area. In other words, in this area overflow oil lubricates movable components in a substantially gravity driven mechanism. A separate seal is not necessary in this insertion area 44 since a housing of a flywheel (not shown) covers the insertion area 44 in which the insertion of the oil rail or oil supply conduit 26 takes place. The insertion of the oil rail into a hole 46 or bore provided in the cylinder block 12 is illustrated by an arrow 48 in Fig. 3.

[0030] If the oil supply conduit 26 is mounted from the front side 42 of the cylinder block 12, a closing cover can be provided for the cylinder block 12 in order to cover the insertion area.

[0031] As mentioned above, the oil delivery from the electric pump 30, which is dedicated for the piston cooling jets 28 or nozzles, may be directed to the main oil gallery 18 when operating conditions do not necessitate cooling of the pistons 16.

[0032] As can be seen from Fig. 3, each piston cooling jet 28, which can be fixed to the oil supply conduit 26 by means of bolts 50, is supplied from the same pipe or rail. However, the pipe or conduit 26 can be split and thus have multiple supplies. This means that the pistons 16 of some cylinders 14 can be supplied separately from the other pistons 16 arranged in other cylinders 14. A corresponding cooling mode can be implemented when some of the cylinders 14 are operated in a driving mode and other cylinders 14 are operated in a breaking mode. In the breaking mode, no fuel is injected into the cylinders 14. The operation mode in which some of the cylinders 14 are in the driving mode and the other cylinders 14 are in the breaking mode can be used to increase the temperature of exhaust gases of the engine 10, which are delivered to an exhaust gas aftertreatment system (not shown), for example for regeneration purposes. In order to increase the temperature an exhaust valve (not shown) of the cylinder 14 can be closed for a particularly long time, such that a particularly high pressure and a particularly high temperature in a combustion chamber of the cylinder 14 is obtained.

[0033] By means of a connecting pipe 52, the oil can be provided from the control valve 34 to the oil supply conduit 26 through the cylinder block 12. Herein, the connecting pipe 52 passes through a wall 54 of the cylinder block 12 (see Fig. 2). Outside the cylinder block 12 a connecting point 56 of the connecting pipe 52 is provided. Therefore, the connection from the oil pipe or oil supply conduit 26 can be made by the connecting pipe 52 to a surface of the cylinder block 12.

[0034] The electric control valve 34 can be arranged in any location and can be connected by an oil pipe to an oil supply location within the oil circuit 24. In this case, the control valve 34 can be connected by a further oil pipe to the connecting point 56. This further oil pipe is illustrated by the arrow 36 in Fig. 1.

[0035] Alternatively, the control valve 34 can be arranged on a flange of the cylinder block 12, which connects an oil supply channel (not shown) to the main oil gallery 18. This oil supply channel can lead from an oil pan of the engine 10 to the main oil gallery 18.

[0036] The control valve 34 can also be arranged inside the engine block or cylinder block 12. Herein, the control valve 34 can be connected to a wiring harness (not shown) located outside the engine block or cylinder block 12. In particular, the control valve 34 can be located at a location at which the control valve 34 connects the oil supply channel to the main oil gallery 18.

[0037] Further, the control valve 34 can be located or arranged on an oil coolant module (not shown), wherein the control valve 34 can connect the oil supply channel to the main oil gallery 18.

[0038] In a further embodiment, the control valve 34 can be arranged on a common flange of the engine 10, which is utilized to fix or hold other oil supplied devices such as an oil filter (not shown). Here again, the control valve 34 can connect the oil supply channel to the main oil gallery 18.

[0039] The space for inserting the oil supply conduit 26 into the cylinder block 12 may be limited. In a case in which a large enough diameter for the oil supply conduit 26 cannot be provided because of space constraints, supplying the piston cooling jets 28 can be done by multiple connecting lines between the oil supply channel and the oil supply conduit 26. Such an arrangement is advantageous in order to minimize a pressure drop. The connecting lines may be connected to one or more control valves 34, in particular electrically controlled control valves 34. This is advantageous if the engine 10 is operated in a split engine operating mode or in the case of a cylinder deactivation and the like.

[0040] Preferably, the cooling of the pistons 16 is map-controlled over engine speed and/or engine load. In such a manner the flow of oil towards the piston cooling jets 28 can particularly well match the actual demand. In other words, the secondary circuit, including the electric pump 30, can actively supply oil to the rail or oil supply conduit 26 on a need basis. Examples of factors or parameters which may be considered herein include an engine temperature, an engine speed, and an engine torque.

[0041] The supply of oil to the piston cooling jets 28 can also be controlled based on a power curve of the engine. Consequently, a control unit 58 of the engine 10, which is schematically shown in Fig. 1, can alternatively or additionally take into account data indicating an engine power curve in operating the electric pump 30 and in controlling the valve 34.

[0042] As can be seen from Fig. 1, the arrangement of the connecting pipe 52 allows for a split of the nozzles or piston cooling jets 28 on the common rail or oil supply conduit 26. Herein, the connecting pipe 52 is fixed to the conduit 26 between a group of two piston cooling jets 28 and a further group of four piston cooling jets 28. Preferably, the second oil supply conduit 26 comprises a device which is operable such that oil can be supplied only to selected piston cooling jets 28.

[0043] As the secondary oil line or second oil supply conduit 26 is mounted directly in the cylinder block 12, the effort associated with providing individual channels supplying the piston cooling jets 28 through separate bores can be avoided.

[0044] Further, the design shown in Fig. 1 can be used in a system that includes the second oil supply conduit 26 shown in Fig. 1 or in a system where the oil is only drawn from the main oil gallery 18. Therefore, such a system which does not include the separate, electric pump 30 does not need to be modified substantially if the secondary oil supply conduit 26 is added. As the engine 10 shown in Fig. 1 includes the exclusive, electric oil pump 30 to supply oil to the piston cooling jets 28, a separate architecture which is independent from the main oil gallery 18 is provided.

[0045] In the secondary oil circuit comprising the electric pump 30 and the second oil supply conduit 26 oil supply to the piston cooling jets 28 is pump-driven based on when the need arises. In contrast, in an engine in which oil delivery is directed from the main oil gallery 18 only, it can happen that the main pump 20 provides oil to the pistons 16 even if no piston cooling is needed.

[0046] A need for piston cooling can arise when the engine temperature exceeds a predefined value. Also, cooling of the pistons 16 can be based on the speed of the engine 10 or the torque. In particular, oil may be provided to the piston cooling jets 28 when the engine operates at higher revolutions per minute (RPM).

[0047] By using the separate, electric pump 30 and the separate oil supply rail or second oil supply conduit 26, which is valve controlled or multi-valve controlled, a decrease in power of the mechanical main oil pump or first pump 20 can be achieved. This leads to an improvement in fuel economy of the internal combustion engine 10.

Claims

CLAIMS1. An internal combustion engine for a vehicle, comprising a first oil supply conduit (18) for supplying oil to at least one movable component of the engine (10), and a second oil supply conduit (26) for supplying oil to at least one piston cooling jet (28) configured to cool at least one piston (16) of the engine (10), wherein the at least one piston (16) is configured to move within a corresponding cylinder (14) of a cylinder block (12) of the engine (10), characterized in that the engine (10) comprises a first pump (20) for pumping oil from a reservoir (22) of an oil circuit (24) of the engine (10) into the first oil supply conduit (18), and a second pump (30) for pumping oil from the oil circuit (24) into the second oil supply conduit (26), wherein the second pump (30) is configured to be operated independently from the first pump (20).
2. The internal combustion engine according to claim 1, characterized in that the first pump (20) is a mechanical pump which is operatively connected to a crankshaft of the engine (10), wherein the second pump (30) is an electric pump.
3. The internal combustion engine according to claim 1 or 2, characterized in that the engine (10) comprises a valve element (34) by means of which oil delivered by the second pump (30) can be supplied into the first oil supply conduit (18) and/or into the second oil supply conduit (26).
4. The internal combustion engine according to any one of claims 1 to 3, characterized in that the second oil supply conduit (26) is embedded inside the cylinder block (12).
5. The internal combustion engine according to claim 4, characterized in that the second oil supply conduit (26) is inserted into a hole (46) provided in the cylinder block (12) from a side (40) of the cylinder block (12), which faces a gear train.
6. The internal combustion engine according to any one of claims 1 to 5, characterized in that the second oil supply conduit (26) is configured to supply oil to a plurality of piston cooling jets (28), wherein each piston cooling jet (28) is configured to cool one piston (16) of the engine (10).
7. The internal combustion engine according to claim 6, characterized in that the second oil supply conduit (26) comprises a device operable such that oil is supplied only to at least a selected one of the plurality of piston cooling jets (28).
8. The internal combustion engine according to any one of claims 1 to 7, characterized by a control unit (58) configured to operate the second pump (30) in dependence on at least one parameter comprising an engine temperature, an engine speed, an engine torque and data indicating an engine power curve.