APPARATUS AND METHOD FOR CONTROLLING PISTON COOLING OIL JET

Abstract

An apparatus for controlling a piston cooling oil jet may include a main gallery supplied with oil, an oil jet gallery defining an oil injection path such that the oil through the main gallery is introduced and is sprayed to a lower portion of a piston, an oil jet valve opening the oil injection path such that the oil supplied to the main gallery is introduced into the oil jet gallery, and a controller electrically connected to the oil jet valve, and determining a target oil pressure through a first factor value corresponding to an RPM and an engine load, a second factor value determined by a predetermined target oil pressure curve, and a third factor value corresponding to an RPM and an oil temperature in the main gallery to control an opening degree of the oil jet valve using the target oil pressure.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2016-0063186 filed on May 24, 2016, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND

Field of the Invention

The present invention relates to an apparatus and method for controlling a piston cooling oil jet. More particularly, it relates to an apparatus and method for controlling a piston cooling oil jet, capable of improving performance of a piston and fuel efficiency.

Description of Related Art

In general, an internal combustion engine compresses and explodes fuel and air introduced into a combustion chamber so that pistons reciprocate up and down, and converts the reciprocation of the pistons into rotational motion using a crank mechanism so as to obtain rotary power.

The internal combustion engine may often rotate at a high speed due to the occurrence of friction between components and a large load applied thereto during operation.

The force applied to such a friction portion may be lost due to resistance, together with the force generated in the expansion stroke of the cylinder added thereto. The friction between components causes the quick wear and short life of the associated components. This causes the performance of the internal combustion engine to deteriorate.

Currently, a piston used in an internal combustion engine is mainly made of an aluminum alloy having light weight and high heat transmissibility. However, an aluminum alloy has a disadvantage in that tensile strength and hardness are reduced at high temperature.

Hence, the head portion of the piston is subjected to high heat as a mixture is combusted in an upper combustion chamber, which may lead to problems relating to a reduction in strength, a heat strain, aluminum adhesion, excess abrasion of rings, etc. Moreover, the higher the temperature of the piston, the faster the degradation of oil, which may cause a carbon deposit to be excessively formed.

Therefore, in order to prevent the engine from being damaged due to these problems, the power of the engine may be adjusted or the passage of coolant may be changed such that the temperature of the piston is maintained below a certain level, but the effect thereof is not great.

Accordingly, the related art adopts a method of cooling a piston by spraying oil from the lower portion of the piston using an oil jet in order to effectively reduce the temperature of the piston. That is, when an oil pump pumps oil and transfers it to a main gallery, the oil jet sprays the oil to the oil jet gallery of the piston, thereby cooling the head portion of the piston.

In the method of cooling the piston, when the engine is started and a pressure is generated in oil, the oil is sprayed, regardless of RPM (revolutions per minute) and a load condition, and therefore the oil jet is always operated. Accordingly, a capacity of the oil pump is increased and the increased capacity acts as the load of the engine, and thus fuel efficiency may deteriorate.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing an apparatus and method for controlling a piston cooling oil jet, capable of improving performance of a piston and fuel efficiency by determining a target oil pressure through a power compensation map, a target oil pressure curve, and a temperature compensation map, which are set using an RPM, an engine load, and an oil temperature, and by comparing and controlling the determined target oil pressure and a current oil pressure to determine an opening degree of an oil jet valve for cooling the piston.

In an exemplary embodiment, an apparatus for controlling a piston cooling oil jet includes a main gallery supplied with oil, an oil jet gallery defining an oil injection path such that the oil passing through the main gallery is introduced thereinto and is sprayed to a lower portion of a piston, an oil jet valve opening the oil injection path such that the oil supplied to the main gallery is introduced into the oil jet gallery, and a controller electrically connected to the oil jet valve, the controller determining a target oil pressure through a first factor value corresponding to an RPM and an engine load, a second factor value determined by a predetermined target oil pressure curve, and a third factor value corresponding to an RPM and an oil temperature in the main gallery, to control an opening degree of the oil jet valve using the target oil pressure.

The controller may include a power compensation map setting device allowing the first factor value to be set, a target oil pressure curve setting device allowing the second factor value to be set, a temperature compensation map setting device allowing the third factor value to be set, and a determination device configured to determine the target oil pressure by adding a first pressure value, which is obtained by multiplying the first and second factor values in the same condition of RPM, to a second pressure value, which is obtained by a difference between the second and third factor values.

The power compensation map setting device may allow the first factor value to be set from an RPM detected by an RPM detection device and an engine load in the RPM.

The target oil pressure curve setting device may allow the second factor value corresponding to an RPM detected by an RPM detection device to be set from the predetermined target oil pressure curve.

The temperature compensation map setting device may allow the third factor value to be set from an RPM detected by an RPM detection device and an oil temperature in the main gallery measured in the RPM.

The oil jet valve may be an electronic solenoid proportional control valve.

The controller may compare the target oil pressure with a current oil pressure in the main gallery and an oil pressure in the oil jet gallery through Proportional Integral (PI) control, and control the opening degree of the oil jet valve.

In another exemplary embodiment, a method of controlling a piston cooling oil jet includes setting a first factor value, a second factor value, and a third factor value using an RPM, an engine load, and an oil temperature in a main gallery, and determining a first pressure value by multiplying the first and second factor values in the same condition of RPM, determining a second pressure value by a difference between the second and third factor values in the same condition of RPM, and determining a target oil pressure by adding the first pressure value to the second pressure value.

The method may further include controlling an opening degree of an oil jet valve by comparing the target oil pressure with a current oil pressure in the main gallery and an oil pressure in an oil jet gallery.

In the setting of a first factor value, a second factor value, and a third factor value, the first factor value may be set from an RPM detected by an RPM detection device and an engine load in the RPM.

In the setting of a first factor value, a second factor value, and a third factor value, the second factor value corresponding to an RPM detected by an RPM detection device may be set from a predetermined target oil pressure curve.

In the setting of a first factor value, a second factor value, and a third factor value, the third factor value may be set from an RPM detected by an RPM detection device and an oil temperature in the main gallery measured in the RPM.

Other aspects and exemplary embodiments of the invention are discussed infra.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

The above and other features of the invention are discussed infra.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating an apparatus for controlling a piston cooling oil jet according to an exemplary embodiment of the present invention;

FIG. 2 is a view illustrating a controller of the apparatus for controlling a piston cooling oil jet according to the exemplary embodiment of the present invention;

FIG. 3 is a graph illustrating a target oil pressure curve for the apparatus for controlling a piston cooling oil jet according to the exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method of controlling a piston cooling oil jet according to another exemplary embodiment of the present invention;

FIG. 5 is a block diagram illustrating a control logic of the method of controlling a piston cooling oil jet according to the exemplary embodiment of the present invention; and

FIG. 6 is an exemplary table for determination of a target oil pressure in the method of controlling a piston cooling oil jet according to the exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various exemplary features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. In addition, detailed descriptions of functions and constructions well known in the art may be omitted to avoid unnecessarily obscuring the gist of the present invention.

FIG. 1 is a view schematically illustrating an apparatus for controlling a piston cooling oil jet according to an exemplary embodiment of the present invention. FIG. 2 is a view illustrating a controller of the apparatus for controlling a piston cooling oil jet according to the exemplary embodiment of the present invention. FIG. 3 is a graph illustrating a target oil pressure curve for the apparatus for controlling a piston cooling oil jet according to the exemplary embodiment of the present invention.

As illustrated in FIG. 1, the apparatus for controlling a piston cooling oil jet includes a main gallery 100, an oil jet gallery 200, an oil jet valve 300, and a controller 400.

First, the main gallery 100 is mounted in a cylinder block of a piston so that oil is supplied along an inside passage of the main gallery by the driving of an oil pump.

In addition, the oil jet gallery 200 defines an oil injection path such that the oil passing through the main gallery 100 is introduced thereinto and is sprayed to the lower portion of the piston.

The oil jet valve 300 opens the oil injection path such that the oil supplied to the main gallery 100 is introduced into the oil jet gallery 200 as the pressure of the oil is increased.

Here, the oil jet valve 300 is an electronic solenoid proportional control valve, and is electrically connected to the controller 400. The opening degree of the oil jet valve 300 may be adjusted by the control of the controller 400.

That is, a conventional oil jet valve is a mechanical control valve, the opening degree of which may not be independently adjusted and controlled by the control of a controller. For this reason, the same amount of oil is always supplied to a piston, regardless of conditions including an RPM, an engine load, and an oil temperature.

In other words, since a conventional flow rate required for cooling a piston is set on the basis of the high-load region of an engine, an excessive surplus flow rate occurs due to the excessive injection of oil in the low-load region of the engine. This may lead to the deterioration of performance of the piston and the deterioration of fuel efficiency. Moreover, there is a problem in that, since the same amount of oil may always be supplied to the piston, it is necessary to increase the capacity of an oil pump.

The controller 400 according to the embodiment may determine a flow rate required for a piston, using an RPM, an engine load in the RPM, and an engine temperature, and thus may effectively control the opening degree of the oil jet valve 300. As a result, it is possible to resolve the above problems.

The controller 400 determines a target oil pressure in the oil jet gallery 200, through a first factor value corresponding to an RPM and an engine load, a second factor value determined by a predetermined target oil pressure curve, and a third factor value corresponding to an RPM and an oil temperature in the main gallery 100, and controls the opening degree of the oil jet valve 300 using the determined target oil pressure.

To this end, the controller 400, which is electrically connected to the oil jet valve 300, includes a power compensation map setting device 410, a target oil pressure curve setting device 420, a temperature compensation map setting device 430, and a determination device 440, as illustrated in FIG. 2.

Here, the power compensation map setting device 410 allows the first factor value to be set from an RPM detected by an RPM detection device and an engine load detected in the RPM.

The target oil pressure curve setting device 420 is preset, and allows the second factor value corresponding to an RPM detected by the RPM detection device to be set from a predetermined target oil pressure curve, as illustrated in FIG. 3.

The temperature compensation map setting device 430 allows the third factor value to be set from an RPM detected by the RPM detection device and an oil temperature in the main gallery 100 measured in the RPM.

The determination device 440 determines the first, second, and third factor values in the same condition of RPM, and determines a target oil pressure by adding a first pressure value, which is obtained by multiplying the first and second factor values, to a second pressure value, which is obtained by a difference between the second and third factor values.

That is, the target oil pressure may be determined by the equation of “Target oil pressure=(first factor value×second factor value)+(second factor value−third factor value)”. The controller 400 compares and controls a current oil pressure in the main gallery 100 and an oil pressure in the oil jet gallery 200 through Proportional Integral (PI) control using the target oil pressure, and thus determines a flow rate required for a piston to control the oil jet valve 300. As a result, it is possible to effectively control the opening degree of the oil jet valve 300.

Accordingly, the apparatus for controlling a piston cooling oil jet according to the embodiment can control the oil jet valve 300 by determining the target oil pressure through the power compensation map, the target oil pressure curve, and the temperature compensation map, which are set using the RPM, the engine load, and the oil temperature in the main gallery 100, adjusting the opening degree of the oil jet valve 300 depending on the high-load region and low-load region of the engine. Therefore, it is possible to improve the performance of the piston and fuel efficiency and to simultaneously reduce the capacity of the oil pump for transferring oil to the main gallery 100.

FIG. 4 is a flowchart illustrating a method of controlling a piston cooling oil jet according to another exemplary embodiment of the present invention. FIG. 5 is a block diagram illustrating a control logic of the method of controlling a piston cooling oil jet according to the exemplary embodiment of the present invention. FIG. 6 is an exemplary table for determination of a target oil pressure in the method of controlling a piston cooling oil jet according to the exemplary embodiment of the present invention.

The method of controlling a piston cooling oil jet and the control logic thereof will be described with reference to FIG. 4 and FIG. 5.

First, a first factor value, a second factor value, and a third factor value are set using an RPM, an engine load, and an oil temperature in a main gallery (S100).

Here, the first factor value is set from an RPM detected by an RPM detection device and an engine load in the RPM. The set first factor value is stored as in the table of a power compensation map illustrated in FIG. 6.

The second factor value is set to be a value corresponding to an RPM detected by the RPM detection device from a predetermined target oil pressure curve illustrated in FIG. 3. The set second factor value is stored as in the table of a target oil pressure curve illustrated in FIG. 6.

The third factor value is set from an RPM detected by the RPM detection device and an oil temperature in the main gallery measured in the RPM. The set third factor value is stored as in the table of a temperature compensation map illustrated in FIG. 6.

When the first, second, and third factor values are set (S100), a first pressure value is obtained by multiplying the first and second factor values in the same condition of RPM, a second pressure value is obtained by a difference between the second and third factor values in the same condition of RPM, and a target oil pressure is determined by adding the first pressure value to the second pressure value (S200).

Finally, an opening degree of an oil jet valve is controlled by comparing the target oil pressure with a current oil pressure in the main gallery and an oil pressure in an oil jet gallery (S300).

Meanwhile, an example of determining a target oil pressure by comparing a first operation condition, in which the RPM is 1800 rpm, the temperature in the main gallery is 60° C., and the engine load is 10%, with a second operation condition, in which the RPM is 1800 rpm equal to that in the first operation condition, the temperature in the main gallery is 100° C., and the engine load is 80%, will be described with reference to FIG. 6.

First, it can be seen that the first factor value is 0.10 through the power compensation map and the second factor value is 155 through the target oil pressure curve in the first operation condition.

Thus, the first pressure value is “0.10×155=15.5 kPa”.

The third factor value is confirmed to be 129 through the temperature compensation map, and the second pressure value is “155−129=26 kPa”. Therefore, the target oil pressure is 41.5 kPa by the equation of “Target oil pressure=first pressure value+second pressure value” indicated in the target oil pressure determination step (S200).

Meanwhile, it can be seen that the first factor value is 0.92 through the power compensation map and the second factor value is 155 through the target oil pressure curve in the second operation condition.

Thus, the first pressure value is “0.92×155=142.6 kPa”.

The third factor value is confirmed to be 155 through the temperature compensation map, and the second pressure value is “155−129=0 kPa”. Therefore, the target oil pressure is 142.6 kPa by the equation of “Target oil pressure=first pressure value+second pressure value” indicated in the target oil pressure determination step (S200).

According to the exemplary embodiment of the present invention, the performance of the piston and fuel efficiency may be improved since the target oil pressure is determined differently depending on the first and second operation conditions and thus the opening degree of the oil jet valve is controlled depending on the conditions.

In the related art, assuming that the flow rate required in a first load condition, in which the RPM is 1800 rpm and the engine load 100%, is 5.2 L/min, and the flow rate required in a second load condition, in which the engine load is 10% in the same RPM, is 0.5 L/min, the flow rate, which is set by the oil jet in the RPM of 1800 rpm, has an upper limit of 7.3 L/min. Therefore, the surplus flow rate in the first load condition is 2.1 L/min, and the surplus flow rate in the second load condition is 6.8 L/min.

Accordingly, since the conventional flow rate required for cooling a piston is set on the basis of the high-load region of an engine, an excessive surplus flow rate may occur in the low-load region of the engine. However, since the opening degree of the oil jet valve can be controlled according to the target oil pressure in the exemplary embodiment, it is possible to prevent the excessive flow rate of oil from occurring in the low-load of the engine.

The present invention has an effect of improving the performance of the piston and fuel efficiency by determining the target oil pressure through the power compensation map, the target oil pressure curve, and the temperature compensation map, which are set using an RPM, an engine load, and an oil temperature, and by comparing and controlling the determined target oil pressure and the current oil pressure to determine the opening degree of the oil jet valve for cooling the piston.

In addition, the present invention has an effect of reducing the capacity of the oil pump, which pumps and transfers oil to the main gallery, since the opening degree of the oil jet valve can be selectively varied to correspond to the RPM, the engine load, and the oil temperature by comparing and controlling the target oil pressure and the current oil pressure.

As is apparent from the above description, the present invention has an effect of improving performance of a piston and fuel efficiency by determining a target oil pressure through a power compensation map, a target oil pressure curve, and a temperature compensation map, which are set using an RPM, an engine load, and an oil temperature, and by comparing and controlling the determined target oil pressure and a current oil pressure to determine an opening degree of an oil jet valve for cooling the piston.

In addition, the present invention has an effect of reducing the capacity of an oil pump, which pumps and transfers oil to a main gallery, since the opening degree of the oil jet valve can be selectively varied to correspond to the RPM, the engine load, and the oil temperature by comparing and controlling the target oil pressure and the current oil pressure.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.

Claims

1. An apparatus for controlling a piston cooling oil jet, comprising:

a main gallery supplied with oil;

an oil jet gallery defining an oil injection path, wherein the oil passing through the main gallery is introduced thereinto and is sprayed to a lower portion of a piston;

an oil jet valve opening the oil injection path, wherein the oil supplied to the main gallery is introduced into the oil jet gallery; and

a controller electrically connected to the oil jet valve, the controller determining a target oil pressure through a first factor value corresponding to an RPM and an engine load, a second factor value determined by a predetermined target oil pressure curve, and a third factor value corresponding to an RPM and an oil temperature in the main gallery, to control an opening degree of the oil jet valve using the target oil pressure.

2. The apparatus of claim 1, wherein the controller including:

a power compensation map setting device allowing the first factor value to be set;

a target oil pressure curve setting device allowing the second factor value to be set;

a temperature compensation map setting device allowing the third factor value to be set; and

a determination device configured to determine the target oil pressure by adding a first pressure value, which is obtained by multiplying the first and second factor values in a same condition of RPM, to a second pressure value, which is obtained by a difference between the second and third factor values.

3. The apparatus of claim 2, wherein the power compensation map setting device allows the first factor value to be set from an RPM detected by an RPM detection device and an engine load in the RPM.

4. The apparatus of claim 2, wherein the target oil pressure curve setting device allows the second factor value corresponding to an RPM detected by an RPM detection device to be set from the predetermined target oil pressure curve.

5. The apparatus of claim 2, wherein the temperature compensation map setting device allows the third factor value to be set from an RPM detected by an RPM detection device and the oil temperature in the main gallery measured in the RPM.

6. The apparatus of claim 1, wherein the oil jet valve is an electronic solenoid proportional control valve.

7. The apparatus of claim 1, wherein the controller is configured to compare the target oil pressure with a current oil pressure in the main gallery and an oil pressure in the oil jet gallery through Proportional Integral (PI) control, and controls the opening degree of the oil jet valve.

8. A method of controlling a piston cooling oil jet, comprising:

setting a first factor value, a second factor value, and a third factor value using an RPM, an engine load, and an oil temperature in a main gallery; and

determining a first pressure value by multiplying the first and second factor values in a same condition of RPM, determining a second pressure value by a difference between the second and third factor values in a same condition of RPM, and determining a target oil pressure by adding the first pressure value to the second pressure value.

9. The method of claim 8, further including controlling an opening degree of an oil jet valve by comparing the target oil pressure with a current oil pressure in the main gallery and an oil pressure in an oil jet gallery.

10. The method of claim 8, wherein, in a setting of a first factor value, a second factor value, and a third factor value, the first factor value is set from an RPM detected by an RPM detection device and an engine load in the RPM.

11. The method of claim 8, wherein, in a setting of a first factor value, a second factor value, and a third factor value, the second factor value corresponding to an RPM detected by an RPM detection device is set from a predetermined target oil pressure curve.

12. The method of claim 8, wherein, in a setting of a first factor value, a second factor value, and a third factor value, the third factor value is set from an RPM detected by an RPM detection device and an oil temperature in the main gallery measured in the RPM.