ES2778705T3 - Lubrication and cooling system for an internal combustion engine - Google Patents

Abstract

Lubrication and cooling system for an internal combustion engine, the combustion engine comprising a suitable piston to correspond with a respective cylinder, the system comprising a multitude of oil consumers grouped in a first and a second group, wherein said second group comprises at least one piston nozzle (s) (NZ) arranged to cool said piston, the system comprising - a main oil circuit with a respective main pump (MP), comprising connection means to be driven directly by said internal combustion engine, wherein said main pump is a controllable variable flow pump arranged to feed oil to said first group of oil consumers (CB -RA, CM, CR); - an auxiliary oil circuit with a respective electric auxiliary pump (AP) arranged to supply oil to said second group of oil consumers (NZ), characterized by - an interconnection valve (SW) capable of selectively operatively interconnecting said first and second circuits, the system being arranged, during operation of the engine brake, - commanding said interconnection valve (SW) to operatively interconnect said main and auxiliary circuits, and then - controlling said main pump to provide relative maximum oil flow , and - controlling said auxiliary pump to extract energy from said oil flow provided by said main pump, thus generating electrical energy.

Description

DESCRIPTION

Lubrication and cooling system for an internal combustion engine

Field of the invention

The present invention relates to the field of cooling and lubrication systems for internal combustion engines.

Description of the prior art.

The engine oil circuit has two different tasks to cool certain components, lubricate other components, and lubricate and cool additional components.

Engine pistons belong to the first of the above categories, being components that, as such, only require cooling. Instead, all the piston connections: the piston pin, the piston pin hole, the small end of the connecting rod, etc. they need lubrication rather than cooling. Document WO2010002293 discloses the possibility of separating the piston oil cooling circuit from the other oil consumers by means of a separate pump.

Therefore, a separate oil circuit for cooling the engine piston (s) with a corresponding separate pump, relative to the remaining and "traditional" engine lubrication circuit arranged to lubricate all components of the combustion engine that require lubrication of the engine oil. Such as crankshaft bearings, valve system, including camshaft bearings and rocker arms, and possibly also actuators to command / change valve timing, for example, to operate engine braking, or a Atkinson / Miller cycle, etc. According to the present description, by "auxiliary oil circuit" it is intended that the separate oil above circuit cool the engine pistons, relative to the main one, including an auxiliary pump that draws the engine oil from an oil sump of the engine. common engine / tank and optionally an auxiliary AC cooler capable of cooling the oil drawn in by the auxiliary pump and at least one nozzle fixed to the wall of the engine to press when opening a cooling passage made in the body of the piston.

Therefore, the secondary pump is controlled to supply correct oil flow to the pistons.

Document JP 2004218468 A discloses a lubrication and cooling system for an internal combustion engine comprising a main and auxiliary oil circuit with their respective main and auxiliary pumps.

Summary of the invention

The main objective of the present invention is to provide a cooling circuit comprising two groups of engine oil consumers and two oil pumps arranged to supply oil independently to said groups of oil consumers capable of improving the efficiency of the engine in operation. engine braking. The operation of the engine brake is well known and consists of the inhibition of fuel injection into the engine cylinders and a sudden release of compressed air when the piston is near top dead center.

Various engine brake operations are known, therefore such details are not relevant to the understanding of the present invention.

During engine brake operation it is also known that the load applied to the internal combustion engine increases, for example by throttling the exhaust gas line of the internal combustion engine to increase its back pressure. These strategies are also known and therefore such details are not relevant to understanding the present invention.

The fundamental principle of the present invention is that, during engine braking, the two independent oil circuits are interconnected, the main pump operates to supply its maximum oil flow, while the auxiliary pump, electric type, is controlled to generate electrical energy from the oil flow supplied by the main pump. Preferably, during electrical generation, the supply of oil for cooling the piston is ensured.

Therefore, a portion of the oil flow pumped by the main pump reaches at least the first group of oil consumers and preferably also the second group of oil consumers, and another portion of the oil flow reaches the auxiliary pump which extracts electrical energy from this other portion of the oil flow. Then all the oil portions fall into the oil sump. The main pump is driven directly by the internal combustion engine, therefore, the operation of the main pump, to supply its maximum oil flow, offers the highest load to the combustion engine. The main pump can have a variable and controllable displacement or it can have a fixed displacement along with a controllable bypass circuit capable of controlling oil flow. It is clear that also in the latter case the maximum or nominal flow can be obtained by closing the bypass circuit of the main pump, which leads to an increase in the hydraulic load seen by the main pump and, therefore, by the Internal combustion engine. In this context, a union directly connects a Engine PTO with pump shaft. According to a preferred embodiment of the invention, a section of the circuit that connects the auxiliary pump with its own oil consumers, even not completely, to maximize the load seen by the main pump and the electrical energy collected by the auxiliary pump.

When the second group of oil consumers also includes bearings, the auxiliary oil circuit may comprise an auxiliary filter to prevent damage to the bearings.

According to a further embodiment of the invention, only the piston nozzles are served by the auxiliary oil circuit and when the engine brake actuation is commanded, first the oil is diverted from the auxiliary circuit to the main circuit to suddenly pressurize the gallery. main circuit and get a quick change of valve timing operation, then the auxiliary pump is controlled to generate electric power which is transported in the vehicle electrical network to which the vehicle battery is connected.

This sudden pressurization helps the main circuit to better serve the switching means operating on the camshaft / rocker arm and eventually additional components to actuate said engine brake. The same bypass can also be exploited to drive another valve timing strategy, however, only during engine brake operation the main pump is controlled to develop its maximum oil flow and the auxiliary pump operates as an electric generator.

The main lubrication circuit can be pressurized by the auxiliary pump also before the engine is started, that is, when the main pump driven by the crankshaft is idle. Therefore, the auxiliary pump is turned on and the biasing means is activated before the engine is started, assisting in the lubrication of the bearings and other components in a condition in which these components are generally stressed due to stress. lack of oil pressurization. Preferably, when starting, the activation of the auxiliary pump and the diverting means is contemporaneous with or a consequence of the activation of the on-board services, such as the fuel pump.

With the exception of the above temporary interconnection between the main and auxiliary circuits via an interconnection valve, the only point in common between the main and auxiliary circuits is the oil sump or oil tank in case the main circuit lubrication is of the dry type.

It is clear that immediately after the interconnection of the circuits, the pumping of oil by the main pump and the extraction of energy by the auxiliary pump are simultaneous actions.

These and other objects are achieved by means of the appended claims, which describe preferred embodiments of the invention, which form an integral part of the present description.

Brief description of the drawings

The invention will become completely clear from the following detailed description, given by way of a merely illustrative and non-limiting example, which will be read with reference to the attached drawing figures, where:

- Figure 1 schematically shows an example of implementation of the present invention.

The same reference numbers and letters in the figures designate the same or functionally equivalent parts. In accordance with the present invention, the term "second element" does not imply the presence of a "first element", first, second, etc., they are used only to improve the clarity of description and should not be construed as limiting.

Detailed description of the preferred embodiments

The present invention is described here with the aid of Figure 1.

An internal combustion engine, as usual, comprises a reciprocating piston with a respective cylinder.

A lubrication and cooling system is implemented to cool the pistons and lubricate other "oil consumers". After its work, the oil, as usual, falls into an oil sump operating system where the oil is collected or, in the case of a dry oil circuit, the oil is collected in a dedicated oil tank.

According to the present invention, an auxiliary oil circuit with an electric auxiliary pump AP draws oil from the oil sump / tank to feed only the piston nozzles NZ that cool the engine piston or optionally also other oil consumers, while a main oil circuit with a respective main MP pump, draws oil from the same oil sump / tank to supply oil to the first group of consumers CB-RA, CM, CR of motor oil, with the exception of the second group of consumers of engine oil served by the auxiliary circuit.

Therefore, oil consumers can be considered divided into a first and a second group, where the first group is served by the main pump / circuit and the second group by the auxiliary pump / circuit and where the second group comprises only or at least said oil piston nozzles NZ. According to the invention, the main pump is of a variable flow pump or alternatively the main MP pump is not controllable, i.e. fixed, but is provided with a bypass pipe connecting the main pump inlet with the main pump outlet through a controllable main MCV valve, so that the oil flow is managed through said controllable auxiliary MCV valve. As both solutions are equivalent, a reference to a variable flow pump also includes a fixed flow pump provided with said bypass means.

According to the invention, the controllable interconnection valve SW connects the main circuit with the auxiliary circuit and the main pump is actuated to provide its maximum oil flow and pressure, and to offer the maximum possible load, that is, nominal the engine internal combustion engine that drives the main pump; at the same time, the auxiliary pump, of electric type, extracts energy from the oil provided by the main pump to generate electrical energy supplied to the vehicular electrical network.

Preferably, when the timing switching means are activated, the controllable interconnection valve SW interconnects both the circuits and the auxiliary pump cooperates with the main pump in pressurizing the switching means SM, i.e. those hydraulic actuators capable of switching engine valve timing. After the valve timing is switched to the engine brake, the auxiliary pump switches from pumping oil to extracting energy from the oil.

In other words, in a first phase, the auxiliary pump cooperates with the main pump, and in a later second phase, the auxiliary pump becomes an electric generator, when the motor rotates in the operation of the motor brake.

In timing valve changes, leading to a different engine braking strategy, such as Atkinson / Miller strategy or internal EGR, after said first phase of cooperation of both pumps / circuits, the SW valve of interconnection disconnects the circuits and both pumps pump oil according to their respective requirements.

Preferably, the main circuit comprises a main MC cooler. Preferably, the auxiliary circuit comprises a separate auxiliary AC cooler and thermally independent from the main cooler.

Preferably, the ambient air cools the auxiliary cooler directly or indirectly through an intermediate vectoring means. According to figure 1, the auxiliary AC cooler is a heat exchanger between the engine oil directed to the piston nozzles and an intermediate vectoring medium that circulates in a secondary circuit, where the heat is released to the environment through the medium. vectorization / SAC ambient air exchanger. However, indirect cooling of the oil circulating in the auxiliary circuit is not mandatory.

Consumers of motor oil are mainly the following:

- Control means CM, including camshaft bearings CB and rocker arms RA, and switching means SM for variable actuation of cylinder valve timing

- possibly idler gear bearings

- air compressor bearings

- turbocharger bearings

- gears

- PTO (power take-off)

- NZ piston nozzle.

Preferably, if the second group of oil consumers comprises only piston nozzles, the auxiliary circuit is not provided with an oil filter, because cooling of the piston does not necessarily require oil filtration.

Preferably, a throttle valve V is arranged in the auxiliary circuit between the interconnection valve SW and the oil piston nozzles NZ.

According to another preferred embodiment that can be combined with the previous ones, the auxiliary circuit comprises an auxiliary pressure sensor PS arranged between the outlet of the auxiliary pump and the piston nozzles NZ, and a control unit, preferably the control unit Controls the auxiliary pump based on a pressure signal generated by the auxiliary pressure sensor, when the engine is started.

According to another preferred embodiment of the invention, even combinable with the others described below, during the engine starting operation, the control unit controls the pumps so that the oil supplied by the auxiliary pump is proportional to the energy supplied by the respective combustion engine and / or the oil supplied by the main pump is proportional to the engine speed.

Preferably, said controls are activated by varying the target pressures within the respective main galleries of the main and auxiliary circuits.

Preferably, during the switching of the timing valve, the piston nozzles are closed, due to the throttle valve V, for a short time just before the activation of the switching means SM capable of varying the activation of the engine valves, for example, for engine brake or internal EGR, and so on. Such a short time is, for example, less than 1 second and generally depends on the operating point of the motor. Therefore, the above oil drift in relation to the throttling of the piston nozzles, causes the oil pressure to rise suddenly within the main oil circuit, by accelerating the dynamics of the switching means. Immediately after the activation of the engine control means CM, the piston cooling is restored, whereby the oil circulating in the auxiliary circuit is led to the piston oil jets.

With control means CM, in general, the devices that control the cylinder valves, such as rocker arms / cam followers, camshaft, etc. are intended. and the relative switching means SM are those, components known per se, capable of varying the actuation time of the valve according to an auxiliary strategy, such as the engine brake or internal EGR, Atkinson, Miller, etc.

This strategy leads to energy savings as the charge offered to the internal combustion engine is collected by recharging the vehicle's batteries.

According to a preferred embodiment of the invention, this "oil bypass" from the auxiliary circuit to the main circuit is also activated for a short time when the engine brake function or the internal EGR or other similar strategies are commanded to activate, that is, during the transition between two or more valve operating strategies. The duration of the oil bypass time interval depends on the dynamics of the switching means SM involved in the switching operation, however, such a time duration <1 second should be sufficient.

An NZ nozzle is fixed with an internal part of the engine body in a lower position so as not to interfere with the piston travel.

The nozzle expels the lubricating oil from the engine into the inlet opening of a passage under the skirt of the piston.

Many changes, modifications, variations, and other uses and applications of the present invention will be apparent to those skilled in the art after considering the specification and accompanying drawings that disclose preferred embodiments thereof. All changes, modifications, variations and other uses and applications that do not depart from the scope of the invention as defined in the claims are considered covered by this invention.

It should be understood that all individual features and / or embodiments can be combined with each other.

Claims (10)

1. Lubrication and cooling system for an internal combustion engine, the combustion engine comprising a suitable piston to correspond with a respective cylinder, the system comprising a multitude of oil consumers grouped in a first and a second group, wherein said second group comprises at least one piston nozzle (s) (NZ) arranged to cool said piston, the system comprising - a main oil circuit with a respective main pump (MP), comprising connection means to be driven directly by said internal combustion engine, wherein said main pump is a controllable variable flow pump arranged to feed oil to said first oil consumer group (CB -RA, CM, CR); - an auxiliary oil circuit with a respective electric auxiliary pump (AP) arranged to supply oil to said second group of oil consumers (NZ), characterized by - an interconnection valve (SW) capable of selectively operatively interconnecting said first and second circuits, the system being arranged, during operation of the motor brake, - give command to said interconnection valve (SW) to operatively interconnect said main and auxiliary circuits, and then - controlling said main pump to provide a relative maximum oil flow, and - controlling said auxiliary pump to extract energy from said oil flow provided by said main pump, thus generating electrical energy. System according to claim 1, further arranged in such a way, during a valve timing switch, - give command to said interconnection valve to interconnect said main and auxiliary circuits, - controlling said main pump to provide a relative maximum oil flow, - controlling said auxiliary pump to cooperate with said main pump to build pressure in the main circuit to accelerate said valve timing switching. System according to claim 2, wherein, after said valve timing change, said engine is turned on, the system is arranged - to give command to said interconnection valve to disconnect said main and auxiliary circuits, - to control said main pump to provide a relative predetermined oil flow, - to control said auxiliary pump to provide a relative predetermined oil flow. System according to any one of claims 1 to 3, wherein said main circuit comprises a main cooler (MC) and said auxiliary circuit comprises an auxiliary cooler (CA) separate and thermally independent of said main cooler. System according to any of the preceding claims, wherein said motor oil consumers (CB-RA, CM, CR) comprise said piston nozzle (NZ) and at least one of the following oil consumers: - Control means (CM) including camshaft bearings (CB), rocker arms (RA) and switching means (SM) to vary the actuation of the cylinder valve timing - eventually crazy gears - air compressor bearings - turbocharger bearings - gears - PTO (power take). System according to any of the preceding claims, wherein when said second group consists of said piston nozzle (NZ), said auxiliary oil circuit does not have a filter. System according to any of the preceding claims, wherein said main pump (MP) has a variable geometry or is provided with a bypass tube that connects an inlet of the main pump with an outlet of the main pump and a valve main throttle valve (MCV), to control this oil flow. 8. Combustion engine comprising an alternative piston with a respective cylinder, and a system according to any of the preceding claims 1 to 7. Land vehicle or fixed installation provided with the combustion engine according to claim 8. 10. Method of managing an engine brake operation in an internal combustion engine provided with a reciprocating piston with a respective cylinder and with a lubrication and cooling system comprising a multitude of engine oil consumers grouped in a first and a second group, wherein said second group comprises at least one piston nozzle (s) (NZ) arranged to cool said piston, wherein the system comprises a main oil circuit with a respective main pump (MP), comprising connection means to be driven directly by said internal combustion engine, wherein said main pump is a controllable variable flow pump arranged to feed oil to said first group of oil consumers (CB-RA, CM, CR) and an auxiliary oil circuit with a respective electric auxiliary pump (AP) arranged to supply oil to said second group of oil consumers (NZ), characterized by the method comprising the following steps: - (i) operational interconnection of said first and second circuits, and then - (ii) controlling said main pump to provide a relative maximum oil flow, and - (iii) controlling said auxiliary pump to extract energy from said oil flow provided by said main pump, thus generating electrical energy.