This application claims the benefit of Korean Patent Application No. 10-2016-0054197, filed on May 2, 2016, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
The present invention relates to a piston for an internal combustion engine, and a cooling channel core and, more particularly, to a piston reciprocating in a cylinder of an internal combustion engine and receiving the pressure of high-temperature and high-pressure explosion in a combustion process to provide motive power to a crankshaft through a connecting rod, and a cooling channel core.
In general, a diesel engine, which is a high-temperature and high-pressure compression ignition engine, has a very high combustion temperature and thus the temperature of a piston thereof is much higher than that of a gasoline engine. As such, a piston ring is burnt, thermal fatigue stress of the piston is increased, and thus the engine is damaged.
To prevent the above problem, a piston of a diesel engine or a gasoline engine includes a cooling channel to cool the piston. The cooling channel is provided at the center of the piston in a ring shape using a coring method, and an oil inlet and an oil outlet are provided at two sides thereof. That is, oil scattered due to pumping of an oil pump during vertical reciprocation of the piston is supplied through the oil inlet, circulates through the cooling channel to cool the piston, and then is discharged through the oil outlet.
In a conventional piston for an internal combustion engine, a cooling channel is generated using a coring method in a piston casting process, and a ceramic core formed of a ceramic material or a salt core formed of compressed salt is used for coring. That is, a ring is generated using a ceramic material or compressed salt and two pillars are provided to support the ring. One of two holes generated due to the pillars serves as the oil inlet and the other thereof serves as the oil outlet after the casting process.
However, when the conventional piston moves upward at high speed in a direction from a location close to an engine oil spray to a location far from the same, the engine oil flows backward in the cooling channel and thus is discharged not only through a refrigerant outlet but also through a refrigerant inlet. As such, cooling efficiency of the piston is lowered.
The present invention provides a piston for an internal combustion engine, and a cooling channel core, the piston and the cooling channel core capable of inducing engine oil to flow from an refrigerant inlet to a refrigerant outlet in a cooling channel of the piston. However, the scope of the present invention is not limited thereto.
According to an aspect of the present invention, there is provided a piston for an internal combustion engine, the piston including a body including a piston pin boss for inserting a piston pin thereinto, and a skirt corresponding to a cylinder wall, and a cooling channel provided in the body to allow a refrigerant for cooling the body, to flow therethrough, and having a ring shape including a first channel provided from a refrigerant inlet to a refrigerant outlet along a first outer circumferential direction of the body, and a second channel provided from the refrigerant inlet to the refrigerant outlet along a second outer circumferential direction of the body, wherein, in the cooling channel, to increase a supply speed and a discharge speed of the refrigerant by inducing the refrigerant supplied through the refrigerant inlet, toward the refrigerant outlet, a first space cross-sectional area of a first part of the first channel located relatively close to the refrigerant inlet is less than a second space cross-sectional area of a second part of the first channel located relatively far from the refrigerant inlet, and a third space cross-sectional area of a third part of the second channel located relatively close to the refrigerant outlet is less than a fourth space cross-sectional area of a fourth part of the second channel located relatively far from the refrigerant outlet.
The cooling channel may have a ring shape in which a lower surface height is equal at every part, an upper surface height of the first part is greater than an upper surface height above the refrigerant inlet, and an upper surface height of the second part is greater than the upper surface height of the first part, and the first channel and the second channel may have point symmetry with respect to a center point of a virtual line connected between the refrigerant inlet and the refrigerant outlet.
The space cross-sectional area of the second part may be 1.05 to 1.30 times greater than the space cross-sectional area of the first part.
A height of an upper surface of the cooling channel may be continuously changed from above the refrigerant inlet to the first part.
An instantaneous tilt angle of a tangent to the upper surface may be rapidly increased from above the refrigerant inlet to the first part.
A height of an upper surface of the cooling channel may be continuously changed from the first part to the second part.
An instantaneous tilt angle of a tangent to the upper surface may be slowly reduced from the first part to the second part.
The cooling channel may have a shape in which an upper surface height is equal and a lower surface height is also equal at every part, and a width of a space cross-section of the second part is greater than a width of a space cross-section of the first part.
The first channel may have a space cross-sectional area gradually increased from the refrigerant outlet to the refrigerant inlet, and the second channel may have a space cross-sectional area gradually increased from the refrigerant inlet to the refrigerant outlet.
The first channel and the second channel may have an equal channel width, and extensions having an extended width or an extended length greater than the channel width may be provided under the refrigerant inlet and the refrigerant outlet.
According to another aspect of the present invention, there is provided a cooling channel core including a core body inserted into a casting mold in a piston casting operation to generate a cooling channel, and having a ring shape including a refrigerant inlet's counterpart provided at a side thereof, a refrigerant outlet's counterpart provided at another side thereof, a first channel's counterpart provided from the refrigerant inlet's counterpart to the refrigerant outlet's counterpart along a first outer circumferential direction, and a second channel's counterpart provided from the refrigerant inlet's counterpart to the refrigerant outlet's counterpart along a second outer circumferential direction, a first part's counterpart provided in the first channel's counterpart of the core body, located relatively close to the refrigerant inlet's counterpart, and having a first cross-sectional area, a second part's counterpart provided in the first channel's counterpart of the core body, located relatively far from the refrigerant inlet's counterpart, and having a second cross-sectional area greater than the first cross-sectional area, a third part's counterpart provided in the second channel's counterpart of the core body, located relatively close to the refrigerant outlet's counterpart, and having a third cross-sectional area, and a fourth part's counterpart provided in the second channel's counterpart of the core body, located relatively far from the refrigerant outlet's counterpart, and having a fourth cross-sectional area greater than the third cross-sectional area.
The first part's counterpart and the second part's counterpart may have an equal lower surface height, an upper surface height of the first part's counterpart may be greater than an upper surface height above the refrigerant inlet's counterpart, an upper surface height of the second part's counterpart may be greater than the upper surface height of the first part's counterpart, and the first channel's counterpart and the second channel's counterpart may have point symmetry with respect to a center point of a virtual line connected between the refrigerant inlet's counterpart and the refrigerant outlet's counterpart.
The cooling channel core may have a shape in which the first part's counterpart and the second part's counterpart have an equal upper surface height and an equal lower surface height, and a width of a cross-section of the second part's counterpart is greater than a width of a cross-section of the first part's counterpart.
The first channel's counterpart may have a space cross-sectional area gradually increased from the refrigerant outlet's counterpart to the refrigerant inlet's counterpart, and the second channel's counterpart may have a space cross-sectional area gradually increased from the refrigerant inlet's counterpart to the refrigerant outlet's counterpart.
The first channel's counterpart and the second channel's counterpart may have an equal channel width, and extensions having an extended width or an extended length greater than the channel width may be provided under the refrigerant inlet's counterpart and the refrigerant outlet's counterpart.
The core body may be a ceramic-based or salt-based core body.
The above and other features and advantages of the present invention will become more apparent by describing in detail embodiments thereof with reference to the attached drawings in which:
Hereinafter, the present invention will be described in detail by explaining embodiments of the invention with reference to the attached drawings.
The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to one of ordinary skill in the art. In the drawings, the thicknesses or sizes of layers are exaggerated for clarity.
As mentioned herein, a piston for an internal combustion engine may linearly reciprocate in a cylinder, provide motive power generated due to a high-temperature and high-pressure gas, to a crankshaft through a connecting rod to generate a rotational force in a combustion process, and operate by receiving power from the crankshaft in suction, compression, and exhaust processes.
As illustrated in
For example, the body 10 may include a piston pin boss 11 for inserting a piston pin (not shown) thereinto, and a skirt 12 corresponding to a cylinder wall. Specifically, for example, the piston pin is a pin for connecting the piston pin boss 11 to a small end of a connecting rod (not shown), and may provide great power received by the piston 100, to a crankshaft through the connecting rod and, at the same time, reciprocate together with the piston 100 at high speed in a cylinder.
As illustrated in
As illustrated in
More specifically, for example, the cooling channel 20 may be a ring-shaped channel including a first channel 21 and a second channel 22.
Here, the first channel 21 may be provided from the refrigerant inlet H1 to the refrigerant outlet H2 along a first outer circumferential direction of the body 10 in such a manner that a portion of the refrigerant supplied through the refrigerant inlet H1 flows in the first outer circumferential direction to cool the body 10 and then is discharged through the refrigerant outlet H2.
The second channel 22 may be provided from the refrigerant inlet H1 to the refrigerant outlet H2 along a second outer circumferential direction of the body 10 in such a manner that another portion of the refrigerant supplied through the refrigerant inlet H1 flows in the second outer circumferential direction to cool the body 10 and then is discharged through the refrigerant outlet H2.
As illustrated in
Here, a space cross-sectional area may refer to a cross-sectional area of a space defined when the first channel 21 or the second channel 22 is cut along a direction perpendicular to the direction of dominant flow of the refrigerant.
As illustrated in
Accordingly, the first part P1 and the second part P2 may be provided near the refrigerant inlet H1 and the third part P3 and the fourth part P4 may be provided near the refrigerant outlet H2 to have point symmetry with respect to the center point P.
Therefore, a refrigerant supplied through the refrigerant inlet H1 may experience a minimum resistance to the initial inflow of the refrigerant as the space cross-sectional areas increase along the first part P1 and the second part P2, and may experience a minimum resistance to the outflow of the refrigerant when flowing through the third part P3 and the fourth part P4. Then, the refrigerant may be guided along an inclined surface of an upper surface of the cooling channel 20 by the movement of the piston 100 according to an embodiment of the present invention, and then may be easily discharged through the refrigerant outlet H2.
Specifically, as illustrated in
More specifically, for example, as illustrated in an enlarged part of
As illustrated in another enlarged part of
According to the above-described shape, since an upper surface height varies while a lower surface height is fixed, the height of the cooling channel 20 may be increased near the refrigerant inlet H1 from the refrigerant inlet H1 toward the refrigerant outlet H2, i.e., in the first channel 21, and thus a space cross-sectional area may be gradually increased.
On the contrary, in the second channel 22, the space cross-sectional area may not be changed or even may be reduced near the refrigerant inlet H1. Accordingly, if necessary, a refrigerant supplied through the refrigerant inlet H1 may be induced to the first channel 21 rather than the second channel 22 and may circulate along an arc direction due to inertia. Thus, the refrigerant may be more easily supplied and discharged.
If the difference in space cross-sectional area is excessively small, the refrigerant may not be appropriately induced. Otherwise, if the difference in the space cross-sectional area is excessively large, air bubbles may be generated or severe spatial restrictions may be caused. After repeated tests and simulations, the best results are achieved when the space cross-sectional area of the second part P2 is 1.05 to 1.30 times greater than the space cross-sectional area of the first part P1. For example, the space cross-sectional area may have a narrow upper part and a wide lower part as illustrated in
As illustrated in
Accordingly, the extensions E may have an inverted funnel shape to allow a high-pressure refrigerant sprayed from an oil spray nozzle (not shown), to be easily supplied into the cooling channel 20.
As illustrated in
As illustrated in
As illustrated in
The first part's counterpart P10 may be provided in the first channel's counterpart 2100 of the core body 2000, may be located relatively close to the refrigerant inlet's counterpart, and may have a first cross-sectional area.
The second part's counterpart P20 may be provided in the first channel's counterpart 2100 of the core body 2000, may be located relatively far from the refrigerant inlet's counterpart, and may have a second cross-sectional area greater than the first cross-sectional area.
The third part's counterpart P30 may be provided in the second channel's counterpart 2200 of the core body 2000, may be located relatively close to the refrigerant outlet's counterpart, and may have a third cross-sectional area.
The fourth part's counterpart P40 may be provided in the second channel's counterpart 2200 of the core body 2000, may be located relatively far from the refrigerant outlet's counterpart, and may have a fourth cross-sectional area greater than the third cross-sectional area.
Specifically, for example, as illustrated in
As illustrated in
As illustrated in
Accordingly, as illustrated in
To guarantee durability against high temperature and high pressure of molten metal in the piston casting operation and to be easily discharged after the piston casting operation, the core body 2000 may be a ceramic-based or salt-based core body.
Therefore, cooling efficiency and flow of the refrigerant may be improved by inducing engine oil to flow from the refrigerant inlet H1 to the refrigerant outlet H2 in the cooling channel 20 of the piston 100.
As illustrated in
As illustrated in
Accordingly, if necessary, a refrigerant supplied through the refrigerant inlet H1 may be induced to the first channel 21 rather than the second channel 22 and may circulate along an arc direction due to inertia. Thus, the refrigerant may be more easily supplied and discharged.
As illustrated in
Here, a first channel 21 may have a space cross-sectional area gradually increased from a refrigerant outlet H2 to a refrigerant inlet H1, and a second channel 22 may have a space cross-sectional area gradually increased from the refrigerant inlet H1 to the refrigerant outlet H2.
Accordingly, if necessary, a refrigerant supplied through the refrigerant inlet H1 may be induced to the first channel 21 rather than the second channel 22 and may circulate along an arc direction due to inertia. Thus, the refrigerant may be more easily supplied and discharged.
As illustrated in
That is, a first channel's counterpart 2100 may have a width Wn and a space cross-sectional area gradually increased from a refrigerant outlet's counterpart to a refrigerant inlet's counterpart, and a second channel's counterpart 2200 may have a width Wn and a space cross-sectional area gradually increased from the refrigerant inlet's counterpart to the refrigerant outlet's counterpart.
As illustrated in
The first channel's counterpart 2100 and the second channel's counterpart 2200 may have an equal channel width CW, and extensions E having an extended length may be provided under the refrigerant inlet's counterpart and the refrigerant outlet's counterpart.
Therefore, a refrigerant may be supplied through the refrigerant inlet H1 with the minimum resistance of flow due to increasing space cross-sectional areas, may be induced along a slope of an outer circumferential surface of the cooling channel 20 due to motion of the piston 300 according to another embodiment of the present invention, and then may be easily discharged through the refrigerant outlet H2.
In addition, the refrigerant may sufficiently reach upper parts of the refrigerant inlet H1 and the refrigerant outlet H2 due to the ribs R and thus cooling efficiency of the refrigerant inlet's counterpart and the refrigerant outlet's counterpart may be improved.
As described above, according to an embodiment of the present invention, a piston for an internal combustion engine, and a cooling channel core, the piston and the cooling channel core capable of improving piston cooling performance by inducing engine oil to flow from an refrigerant inlet to a refrigerant outlet in a cooling channel of the piston. However, the scope of the present invention is not limited to the above effect.
While the present invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
---|---|---|---|
10-2016-0054197 | May 2016 | KR | national |