GB2484748A

GB2484748A - Oil Supply Control for Internal Combustion Engine Pistons

Info

Publication number: GB2484748A
Application number: GB1017954.7A
Authority: GB
Inventors: Winfried Krebs; Torsten La Hnert; Helmut Hans
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2010-10-18
Filing date: 2010-10-18
Publication date: 2012-04-25
Also published as: GB201017954D0; CN102454467A

Abstract

A internal combustion engine with pistons has a first oil gallery 44 for selectively supplying oil to the pistons under the control of a valve 50. The engine can include a further oil gallery 34 for bearing lubrication, and the valve is controlled by a control device 54 providing control signals such that the valve can provide oil for piston cooling. The valve can be controlled in dependence on one or more operating parameters, e.g. oil temperature or pressure, coolant temperature, engine speed and engine load, and may be a solenoid valve. The first oil gallery may be connected to piston cooling nozzles 46 which may spray oil to the hottest part of each piston.

Description

Oil Supply for Pistons The present invention relates to a system for the supply of oil to the pistons of an internal combustion engine and more particular to the supply of oil to a piston jet gallery for the purposes of cooling the pistons.

In existing oil supply systems for internal combustion engines a network of supply conduits is used to supply oil from a common source to various engine components including the main bearing for lubrication purposes, and the pistons (for cooling purposes). To maintain proper lubrication of the main bearing it requires lubrication at all times. However, the piston cooling nozzles only require oil to spray on the pistons at particular times. Accordingly, in known systems, the oil supply to the piston jet gallery is under the control of a spring-actuated valve. A ball member of the valve is exposed to the pressure of oil in the system. When a particular pressure value is reached, it urges the ball member against the force of the spring and the valve opens to allow oil to pass through the piston jet gallery and emerge from the cooling nozzles.

A disadvantage cf the above system is that the optimum times for the jets to cool the pistons are actually determined by factors in addition to pressure. This leads to less than optimal efficiency of operating the engine, which leads to increased fuel consumption and carbon dioxide emissions.

Aspects of the present invention seek to overcome, or at least reduce, the above disadvantages.

According to a first aspect of the present invention, there is provided an internal combustion engine comprising a bearing and a plurality of pistons, an oil supply, and conduit means for supplying oil from the oil supply to the bearing and to the pistons, wherein the conduit means comprises a first conduit member arranged to supply oil to the bearing and a second conduit member arranged to supply oil to the pistons, the second conduit member incorporating a valve for controlling the supply of oil to the pistons, wherein a control device is provided for the valve which supplies signals to control the valve. I5

An advantage of the above engine is that the oil supply for cooling the pistons can be controlled independently of the oil supply for lubricating the bearing. This leads to a more efficient oparation of the engine and thus serves to reduce fuel consumption and carbon dioxide emissions.

in a preferred engine, the control device controls the valve in dependence upon one or more operating parameters. This enables the engine to be controlled independently of the pressure in the bearing lubricant circuit, and/or to take into account a wide range of factors which affect the optimal times at which to cool the pistons.

Thus opening and closing of the valve may be controlled in dependence or one or more of the following factors: -the temperature of the oil; -the temperature of a coolant in a cooling circuit for the engine; -the temperature of a cylinder block of the engine; -the temperature of a cylinder head of the engine; -the engine speed; and/or -the engine load.

In addition, or instead, the valve may be controlled by a user-operated switching element. This gives a user the opportunity to override the control device if special conditions prevail.

Alternatively, or in addition, the valve may be controlled in accordance with a predetermined program. Again this enables the control device to be overridden at certain times.

According to a second aspect of the present invention, there is provided an oil supply system for an internal combustion engine comprising a plurality of pistons, wherein oil is fed to conduit means for supplying outlets for cooling the pistons with oil, the conduit means incorporating a valve, wherein the valve is controlled by at least variable other than oil pressure.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a schematic diagram of a prior art oil system; Figure 2 shows an oil supply system in accordance with the present invention; and Figure 3 shows control circuitry of the oil supply system of Figure 2.

Referring to the drawings, Figure 1 shows a prior art system for supplying oil to the components of an automotive internal combustion engine 20 with arrows indicating the direction of oil flow. Oil is supplied from a reservoir 12 via a conduit 14 to an oil gallery 16 to lubricate the main bearing and to cool the piston jets. The oil is recirculated via a filter back to reservoir 12.

Oil for lubricating the main bearing passes through a plurality of conduits 24. Oil for cooling the piston jets passes through respective nozzles 22. Each nozzle incorporates an integrated pressure-responsive valve 26 comprising a ball biased in a valve-closing direction by a coil spring. When the pressure in the oil system exceeds a predetermined threshold value, it lifts the ball away from its seating and the spring is compressed to allow the valve to open and the piston to be cooled The gallery 16 also supplies further engine components such as a first head oil supply 38 for a valve train and, via a conduit 42, a second head oil supply 40 for a variable cam phaser.

With average ambient temperatures, the valves 26 are in a closed state before and immediately after the engine is switched on. As the revolutions increase, the pressure of the oil increases. When a predetermined threshold is reached the pressure of the oil opens the valves 26 and passes out of the nozzles to cool the respective pistons.

Under cold conditions, e.g. in winter, the valves 26 are again in a closed condition before the engine is switched on.

However, when the engine is switched on, the oil pressure immediately rises, since the oil is highly viscous at low temperatures. Accordingly, the valves 26 open immediately. As the oil temperature rises during subsequent operation of the engine, so its viscosity and pressure decreases. Thus the valves 26 can repeatedly close and open as a result of varying engine operating parameters, such as engine speed and load, influencing the oil pressure.

Referring to Figure 2, there is shown a system 30 in accordance with the present invention for supplying oil to the components of an internal combustion engine. Clean oil enters the oil main gallery 34 of a network of conduits via inlet pipe 32, the direction of the flows of oil being shown by the arrows. The main bearing of the engine is lubricated by oil passing through conduits 36.

Gallery 34 is further connected to a conduit 42. Conduit 42 supplies oil to a separate piston jet gallery 44 which is connected to piston cooling nozzles 46. Each nozzle 46 sprays oil directed at the hottest part of its respective piston, which is typically at the exhaust side. Oil from the piston jet gallery is recirculated back to the reservoir 12.

The fluid connection between conduit 42 and gallery 44 is selectively opened and blocked by a solenoid-actuated valve 50. The opening and closing of valve 50 are under the control of signals supplied to the valve over one or more lines 52 from a control unit 54.

The engine incorporates respective sensors for detecting the temperature and pressure of the oil in the system 30. In accordance with the contents of a corresponding look-up table, valve 50 is open or closed so that the pistons are cooled when the relevant conditions prevail.

An advantage of the above-described arrangement is that oil can be supplied to the piston jets in a finely-tuned manner, rather than coarsely when determined in proportion to oil pressure alone. It is more sophisticated, since it can take into account all operating conditions. This permits a more efficient operation of the engine, leading to lower fuel consumption and carbon dioxide emissions.

In addition to, or instead of, one or both of the above variables, the valve 50 may be controlled in response to the temperature of the water or other coolant in a cooling circuit of the engine, the temperature of the cylinder block, the temperature of the cylinder head, the engine speed and the engine load.

Figure 3 is a diagram showing the various sensors, signals from which can be used to control the unit 54. Sensor 60 is attached to the metallic material of the cylinder block 62 to sense the temperature thereof and to supply temperature-dependent signals on line 64 to control unit 54.

A water pump 72 for circulating cooling water through conduits in engine 20 has a map-controlled thermostat 70. Signals dependent on the temperature of the water in the cooling system are supplied via a line 74 to control unit 54.

The oil reservoir or sump 12 has a sensor 80 for detecting the oil temperature and supplying a corresponding signal on line 84 to control unit 54.

A tachometer 90 is provided to provide control unit 54 with a signal proportional to engine speed on line 94. A further sensor 100 is associated with the accelerator pedal of the vehicle to provide a signal on line 104 which is dependent on engine load.

One or more of the sensors 60, 70, 80, 90 and/or 100 may be omitted as desired. For example, there may be only one temperature sensor 60, 70 or 80.

The control unit 54 comprises a microcomputer which applies algorithms in dependence on the above-mentioned variables to determine when the solenoid of the valve 50 is to be actuated to open the valve.

The algorithms in control unit 54 are configured differently for different types of engine. For a turbo-engine, for example, which typically operates with high load, a mean pressure lies in the range 15-20 bar. Naturally-aspirated and direct injection engines operate with different average conditions; for example a naturally-aspirated engine has a mean pressure closer to 12 bar.

Signals representing the measured variables may be derived from any convenient detection location in the engine.

The solenoid of valve 50 may be actuated intermittently instead of substantially continuously. A separate control element 110 may be provided to control this factor.

Alternatively, control element 110 may be incorporated in control unit 54.

The control unit 54 can be accommodated within the same housing as valve 50.

In another modification, the valve is controlled solely by an element which is independent of prevailing operating conditions, e.g. a switch operated by a user or in accordance with a predetermined program.

Reference Numerals Oil supply system 10 Oil reservoir 12 Conduit 14 Oil gallery 16 Engine 20 Nozzles 22 Conduits 24 Valves 26 Oil Supply System 30 Inlet pipe 32 Oil Main Gallery 34 Conduits 36 IS Oil supplies 38,40 Conduit 42 Piston Jet Gallery 44 Nozzles 46 Valve 50 Lines 52 Control Unit 54 Sensor 60 Cylinder Block 62 Line 64 Thermostat 70 Water Pump 72 Line 74 Sensor 80 Line 84 Tachometer 90 Line 94 Sensor 100 Line 104 Control Element 110

Claims

Claims 1. An internal combustion engine (20) comprising a bearing and a plurality of pistons, an oil supply (12), and conduit means (32, 34, 42, 44) for supplying oil from the oil supply to the bearing and to the pistons, wherein the conduit means comprises a first conduit member (34) arranged to supply oil to the bearing and a second conduit member (44) arranged to supply oil to the pistons, the second conduit member incorporating a valve (50) for controlling the supply of oil to the pistons, wherein a control device (54) is provided for the valve which supplies signals to control the valve.
2. An engine according to claim 1, wherein the control device (54) controls the valve (50) in dependence upon one or more operating parameters.
3. An engine according to claim 2, wherein the valve (50) is controlled in dependence on the temperature of the oil.
4. An engine according to claim 2 or 3, wherein the valve (50) is controlled in dependence on the temperature of a coolant in a cooling circuit for the engine.
5. An engine according to any one of claims 2 to 4, wherein the valve (50) is controlled in dependence on the temperature of a cylinder block of the engine.
6. An engine according to any one of claims 2 to 5, wherein the valve (50) is controlled in dependence on the temperature of a cylinder head of the engine.
7. An engine according to any one of claims 2 to 6, wherein the valve (50) is controlled in dependence on the engine speed.
8. An engine according to any one of claims 2 to 7, wherein the valve (50) is controlled in dependence on the engine load.
9. An engine according to any preceding claim, wherein the valve (50) is controlled by a user-operated switching element.
10. An engine according to any preceding claim, wherein the valve (50) is controlled in accordance with a predetermined program.
11. An oil supply system (30) for an internal combustion engine comprising a plurality of pistons, wherein oil is fed to conduit means (32, 34, 42, 44) for supplying outlets for cooling the pistons with oil, the conduit means incorporating a valve (50), wherein the valve is controlled by at least one variable other than oil pressure.
12. An oil supply system according to claim 11, wherein the valve (50) is controlled by one or more of the temperature of the oil, the temperature of a coolant in a cooling circuit for the engine, the temperature of a cylinder block and/or cylinder head of the engine, the engine speed and the engine load.
13. An oil supply system according to claim 11 or 12, wherein the valve (50) is additionally controlled by the oil pressure.
14. An oil supply system according to any of claims 11 to 13, wherein the valve (50) is additionally controlled by a user-operated switching element.
15. An oil supply system according to any of claims 11 to 14, wherein the valve (50) is additionally controlled by a predetermined program.