JP2019074014A - Piston of internal combustion engine - Google Patents

Abstract

To increase an amount of heat transferred from a piston to oil.SOLUTION: In a piston 9 of an internal combustion engine, an introduction passage 21 which introduces jetted oil from one end, a cooling cavity 22 which communicates with the other end of the introduction passage 21 and in which the oil flowing from the introduction passage 21 flows, and a discharge passage 23 which communicates with the cooling cavity 22 at one end and discharges the oil flowing from the cooling cavity 22 from the other end are provided. The cooling cavity 22 has groove parts 22c, 22d, 22e along an oil flowing direction in the cooling cavity 22.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a piston of an internal combustion engine.

  Conventionally, there is known a configuration in which a flow path through which oil injected from an oil jet flows is provided in a piston of an internal combustion engine (see, for example, Patent Document 1). In this configuration, the oil flows in the flow path in the piston, so that the piston can be cooled.

Unexamined-Japanese-Patent No. 5-256193

  In the piston having the above-described configuration, it is desirable to increase the amount of heat transfer from the piston to the oil in order to enhance the cooling efficiency.

  An object of the present invention is to provide a piston of an internal combustion engine capable of increasing the amount of heat transfer from the piston to the oil.

  The piston of the internal combustion engine according to the present invention communicates with the introduction channel for introducing the fluid injected from the injection device from one end and the other end of the introduction channel, and a cooling cavity through which the fluid flowing from the introduction channel flows A piston of an internal combustion engine in which an end is in communication with the cooling cavity, and a discharge flow passage for discharging the fluid introduced from the cooling cavity from the other end is provided in the inside of the engine; It has one or more grooves along the flow direction of the fluid in the cavity.

  According to the present invention, the amount of heat transfer from the piston to the oil can be increased.

The schematic diagram which shows the structure of the internal combustion engine which concerns on embodiment of this invention Side view showing an oil passage according to an embodiment of the present invention Sectional drawing which shows the groove part which concerns on the modification of this invention The perspective view which shows the cooling cavity which concerns on the modification of this invention, and sectional drawing which shows a groove part

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the configuration of an internal combustion engine 100 according to an embodiment of the present invention will be described using FIG. FIG. 1 is a schematic view showing a configuration example of an internal combustion engine 100 according to the present embodiment.

  The internal combustion engine 100 is, for example, a diesel engine mounted on a vehicle. Although the case where internal combustion engine 100 is a diesel engine will be described as an example in the present embodiment, the present invention is not limited to this. The internal combustion engine 100 may be a reciprocating engine having a piston that reciprocates.

  An internal combustion engine 100 has a cylinder head 1 and a cylinder block 2.

  An intake port 3 and an exhaust port 4 are formed in the cylinder head 1. The intake port 3 is a flow path for introducing fresh air, and the exhaust port 4 is a flow path for discharging exhaust gas. An intake valve 5 is disposed at the intake port 3, and an exhaust valve 6 is disposed at the exhaust port 4. The intake valve 5 and the exhaust valve 6 are opened and closed in conjunction with the reciprocating movement of the piston 9.

  Further, in the cylinder head 1, an injector 7 for injecting fuel into the combustion chamber 10 is disposed between the intake valve 5 and the exhaust valve 6.

  A cylinder 8 is formed in the cylinder block 2, and a piston 9 that reciprocates the cylinder 8 is disposed. In FIG. 1, arrow A indicates a first direction, and arrow B indicates a second direction opposite to the first direction. The piston 9 alternately performs movement in the first direction and movement in the second direction as reciprocating movement. Further, in FIG. 1, 9 a indicates the top surface of the piston 9 and 9 b indicates the bottom surface of the piston 9.

  Inside the piston 9 is provided an oil flow passage 20 through which oil (lubricant oil, an example of fluid) injected from the oil jet 13 flows. The details of the oil flow passage 20 will be described later with reference to FIG.

  Further, in the cylinder block 2, a connecting rod 11 and a crankshaft 12 are disposed. One end of the connecting rod 11 is connected to the piston 9 and the other end is connected to the crankshaft 12. The connecting rod 11 and the crankshaft 12 rotate in conjunction with the reciprocating movement of the piston 9. In FIG. 1, an arrow C indicates the rotational direction of the piston 9.

  Further, the cylinder block 2 is provided with an oil jet 13 (an example of an injection device) for injecting the oil supplied from the oil supply passage 16 toward the bottom surface 9 b of the piston 9.

  The oil jet 13 has a valve 14 and a nozzle 15.

  The valve 14 is opened and closed in accordance with the pressure (hereinafter referred to as oil pressure) and temperature of oil. When the valve 14 is in the closed state, the oil from the oil supply passage 16 is prevented from flowing into the nozzle 15. When the valve 14 is in the open state, the oil from the oil supply passage 16 is allowed to flow into the nozzle 15.

  The nozzle 15 is bent so that the oil is jetted toward the bottom surface 9b of the piston 9, and has a tapered shape in which the diameter is reduced toward the tip.

  The oil jet 13 is not limited to one having the above-described configuration. For example, the oil jet 13 may not have the valve 14 or the nozzle 15 may not have the tapered shape.

  The oil supply path 16 connects the oil jet 13 and the oil reservoir 17 (for example, an oil pan). Further, the oil supply passage 16 is provided with an oil pump 18 driven by the rotation of the crankshaft 12. By driving the oil pump 18, the oil stored in the oil pan reservoir 17 is pumped up and supplied to the oil jet 13 via the oil supply passage 16.

  The configuration of the internal combustion engine 100 has been described above.

  Next, the oil flow path 20 provided in the piston 9 according to the present embodiment will be described with reference to FIG. FIG. 2 is a perspective view of the oil passage 20 as viewed obliquely from above.

  As shown in FIG. 2, the oil flow passage 20 has a substantially cylindrical introduction flow passage 21, an annular cooling cavity 22, and substantially cylindrical discharge flow passages 23 and 24. The oil flow direction of the cooling cavity 22 is provided in a plane perpendicular to the reciprocating direction of the piston 9 (see arrows A and B in FIG. 1), and the oil in the inlet channel 21 and the outlet channel 23 and 24 is The direction of flow is provided in a plane parallel to the reciprocation direction of the piston 9. In the present embodiment, although the oil flow passage 20 is provided with two of the discharge flow passages 23 and 24, the oil flow passage 20 may be provided with only the discharge flow passage 23.

  One end of the introduction flow passage 21 communicates with the flow passage connecting portion 22 a of the cooling cavity 22, and the oil jetted by the oil jet 13 is introduced from the other end. The oil introduced into the introduction flow passage 21 flows into the flow passage connecting portion 22 a of the cooling cavity 22.

  The cooling cavity 22 has flow path connection portions 22a and 22b and grooves (which may be called flow paths) 22c, 22d and 22e.

  One end of the introduction channel 21 is connected to the channel connection portion 22a. On the other hand, one end of each of the discharge flow paths 23, 24 is connected to the flow path connection portion 22b. The radial cross section of each of the flow path connection portions 22a and 22b is, for example, substantially elliptical.

  The grooves 22c, 22d, 22e are respectively flow paths formed along the oil flow direction (the direction of the arrow E shown in FIG. 2) in the cooling cavity 22.

  The grooves 22c, 22d and 22e respectively connect the flow path connection portion 22a and the flow path connection portion 22b. The radial cross section of each of the grooves 22c, 22d, 22e is, for example, substantially circular.

  The grooves 22c, 22d, and 22e are each provided in a spiral shape.

  In such a cooling cavity 22, the oil that has flowed into the flow path connection portion 22a from the introduction flow path 21 flows through the groove portions 22c, 22d, and 22e toward the flow path connection portion 22b.

  The flow path connecting portions 22a, 22b and the grooves 22c, 22d, 22e described above may be formed by penetrating the inside of the piston 9 into the shape of the cooling cavity 22 shown in FIG. 2, or a plurality of pipes In the form of the cooling cavity 22 shown in FIG. 2 and may be formed by embedding the pipes in the interior of the piston 9.

  One end of each of the discharge flow paths 23, 24 communicates with the flow path connecting portion 22b of the cooling cavity 22, and the oil flowing from the flow path connecting portion 22b of the cooling cavity 22 is discharged from the other end to the outside of the piston 9. .

  The oil flow passage 20 has been described above.

  As described above, according to the present embodiment, the cooling cavity 22 is characterized in that the grooves 22c, 22d, and 22e along the oil flow direction in the cooling cavity 22 are provided. Thereby, the area in which the oil in the cooling cavity 22 contacts the piston 9 can be increased. Therefore, the amount of heat transfer from the piston 9 to the oil increases, and the cooling efficiency is improved.

  Furthermore, by providing the grooves 22c, 22d, 22e in a spiral shape, the time for which the oil stays in the cooling cavity 22 can be increased, and the cooling efficiency is further improved.

  The present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present invention. Each modification will be described below.

[Modification 1]
In the embodiment, the case where the three grooves 22c, 22d, and 22e are provided has been described as an example, but the number of grooves is not limited to three.

[Modification 2]
In the embodiment, the case where the grooves 22c, 22d, and 22e are provided in a spiral shape is described as an example, but the grooves 22c, 22d, and 22e may not be in a spiral shape. For example, the grooves 22c, 22d, 22e may be provided with a fixed positional relationship with each other. An example of this case is shown in FIG. FIG. 3 is a view showing an example of a cross section in the radial direction of the grooves 22c, 22d, 22e. The grooves 22c, 22d, 22e may be provided between the flow path connection portion 22a and the flow path connection portion 22b while maintaining the positional relationship shown in FIG.

[Modification 3]
For example, as shown in FIG. 4A, the cooling cavity 22 has a constant cross-section along the radial direction (in other words, a cross-section perpendicular to the flow direction of the oil). The groove may be provided on the inner wall (inner peripheral surface) of the cooling cavity 22 if it is substantially rectangular. FIG. 4 (b) is a diagram showing a cross section in the radial direction of the cooling cavity 22 shown in FIG. 4 (a). As shown in FIG. 4B, grooves 22f, 22g, 22h and 22i are formed on each surface of the cooling cavity 22. As shown in FIG. The grooves 22f, 22g, 22h, 22i are formed along the oil flow direction in the cooling cavity 22 shown in FIG. 4A while maintaining the positional relationship shown in FIG. 4B.

  Even in such a configuration, the area in which the oil in the cooling cavity 22 contacts the piston 9 can be increased, so the amount of heat transfer from the piston 9 to the oil increases, and the cooling efficiency is improved.

  In the example of FIG. 4B, the shapes of the grooves 22f, 22g, 22h, and 22i are substantially semi-elliptic, but the present invention is not limited thereto.

  Moreover, although four groove parts 22f, 22g, 22h, and 22i are provided in the example of FIG.4 (b), at least one groove part should just be provided among them.

  Further, in the example of FIG. 4B, one groove is provided on each surface of the cooling cavity 22, but two or more grooves may be provided on each surface.

  Also, the grooves 22f, 22g, 22h, 22i shown in FIG. 4B may be provided in a spiral, for example, similarly to the grooves 22c, 22d, 22e shown in FIG.

[Modification 4]
In the embodiment, although the case where the discharge flow paths 23 and 24 are provided to the cooling cavity 22 as shown in FIG. 2 has been described as an example, the present invention is not limited to this. For example, the discharge flow paths 23 and 24 may be provided in a direction parallel or oblique to the flow direction of the oil in the cooling cavity 22. Thus, the oil flowing in the cooling cavity 22 is easily discharged from the discharge flow passages 23 and 24 by the received centrifugal force.

[Modification 5]
The introduction flow channel 21 may be shaped so that oil can easily flow from the introduction flow channel 21 into the cooling cavity 22.

  For example, an end of the introduction channel 21 connected to the cooling cavity 22 (channel connection 22a) is made to enter the cooling cavity 22 (channel connection 22a), and an opening portion of the end May be directed to the flow direction of the oil in the cooling cavity 22 (see arrow E in FIG. 2). Thus, the oil can easily flow into the cooling cavity 22 from the introduction channel 21.

[Modification 6]
The first surface (e.g., the upper surface) of the cooling cavity 22 and the second surface (e.g., the lower surface) opposed to the first surface may be inclined with respect to the reciprocating direction of the piston 9. Thus, along with the reciprocation of the piston 9, an inertia force is constantly exerted on the oil flowing into the cooling cavity 22 from the introduction flow passage 21 so that the oil is pushed out to the discharge flow passage 23 side. Thus, the flow rate of oil in the cooling cavity 22 can be further increased.

[Modification 7]
A storage portion in which oil is stored may be provided in the middle of the discharge flow path 23. In this storage section, the oil that has flowed into the storage section is unlikely to backflow to the upstream side (the connection portion side with the cooling cavity 22) of the discharge flow path 23, and the downstream side of the discharge flow path 23 (oil to the outside of the piston 9) It is a shape which is easy to be discharged to the opening part side which is discharged.

  For example, the storage unit includes an inlet through which oil flows in from the upstream side of the discharge flow passage 23, an outlet through which oil stored in the storage unit flows out downstream of the discharge flow passage 23, and a discharge flow passage from the outlet And 23, an inclined portion in which the radial cross-sectional area continuously decreases in the downstream direction of the H.23.

  When the center of the crank pin 12b shown in FIG. 1 is in the upper half of the imaginary line D (a straight line passing through the crankshaft center 12a and perpendicular to the direction of the reciprocation of the piston 9), The oil exerts an inertial force in the direction of arrow A. At this time, the oil jetted by the oil jet 13 is pushed into the introduction channel 21, but the pushing pressure is reduced by the inertia force in the direction of the arrow A. Due to the reduced push-in pressure, the oil passes through the cooling cavity 22 and then flows into the discharge flow path 23 to store the oil in the reservoir.

  On the other hand, when the center of the crank pin 12b shown in FIG. 1 is in the lower half of the imaginary line D, the oil in the piston 9 exerts an inertial force in the direction of the arrow B. At this time, the oil stored in the storage section is discharged.

  Thus, in conjunction with the reciprocation of the piston 9, oil storage and discharge are repeatedly performed in the storage section.

  When the oil in the storage section is discharged, the pressure in the storage section decreases, and the pressure in the cooling cavity 22 (upstream of the discharge flow path 23) also decreases. Emissions are promoted. Therefore, according to the piston 9 of the present embodiment, the flow rate of oil flowing in the cooling cavity 22 can be increased.

  The storage unit may be provided not only in the discharge flow channel 23 but also in the discharge flow channel 24.

  In the above, each modification was demonstrated. Each modification mentioned above may be combined suitably.

<Summary of this disclosure>
The piston of the internal combustion engine according to the present invention communicates with the introduction channel for introducing the fluid injected from the injection device from one end and the other end of the introduction channel, and a cooling cavity through which the fluid flowing from the introduction channel flows A piston of an internal combustion engine in which an end is in communication with the cooling cavity, and a discharge flow passage for discharging the fluid introduced from the cooling cavity from the other end is provided in the inside of the engine; It has one or more grooves along the flow direction of the fluid in the cavity.

  In the piston of the internal combustion engine, the groove may be formed on the inner wall of the cooling cavity.

  Further, in the piston of the internal combustion engine, the groove may be provided in a spiral shape.

  Further, in the piston of the internal combustion engine, the cooling cavity is annular, and the discharge flow passage is provided in a direction parallel or oblique to the flow direction of the fluid in the cooling cavity. It is also good.

  Further, in the piston of the internal combustion engine, the other end of the introduction flow path enters the cooling cavity, and the opening of the other end of the introduction flow path faces the fluid flow direction in the cooling cavity. It is also good.

  Further, in the piston of the internal combustion engine, the first surface of the cooling cavity and a second surface opposite to the first surface may be inclined with respect to a surface perpendicular to the reciprocating direction of the piston.

  Further, in the piston of the internal combustion engine, a storage portion in which the fluid is stored is provided between the upstream side and the downstream side of the discharge flow path, and the storage portion is arranged from the upstream side of the discharge flow path An inlet through which the fluid flows in, an outlet through which the fluid stored in the reservoir flows out toward the downstream side of the discharge passage, and a cross-sectional area in a radial direction from the outlet toward the downstream side of the discharge passage May have a continuously decreasing slope.

  The present invention is applicable to a piston that reciprocates an internal combustion engine.

Reference Signs List 1 cylinder head 2 cylinder block 3 intake port 4 exhaust port 5 intake valve 6 exhaust valve 7 injector 8 cylinder 9 piston 9 a piston top surface 9 b piston bottom surface 10 combustion chamber 11 connecting rod 12 crankshaft 13 oil jet 14 valve 15 nozzle 16 Oil supply passage 17 oil reservoir 18 oil pump 20 oil passage 21 introduction passage 22 cooling cavity 22a, 22b passage connection 22c, 22d, 22e, 22f, 22g, 22h, 22i groove 23, 24 discharge passage 100 internal combustion organ

Claims (7)

An introduction flow passage for introducing the fluid injected from the injection device from one end, a cooling cavity in communication with the other end of the introduction flow passage, the fluid flowing from the introduction flow passage, and one end communicating with the cooling cavity An internal combustion engine piston provided internally with a discharge flow path for discharging the fluid flowing in from the cooling cavity from the other end,
The cooling cavity has one or more grooves along the flow direction of the fluid in the cooling cavity,
piston. The groove is formed on the inner wall of the cooling cavity,
The piston according to claim 1. The groove is provided in a spiral shape.
A piston according to claim 1 or 2. The cooling cavity is annular,
The discharge channel is
It is provided in a direction parallel or oblique to the flow direction of the fluid in the cooling cavity,
The piston according to any one of claims 1 to 3. The other end of the introduction channel enters into the cooling cavity, and the open end of the other end of the introduction channel faces the flow direction of the fluid in the cooling cavity,
The piston according to any one of claims 1 to 4. The first surface of the cooling cavity and a second surface opposite to the first surface are inclined with respect to a surface perpendicular to the reciprocating direction of the piston.
The piston according to any one of claims 1 to 5. There is a reservoir for storing the fluid between the upstream side and the downstream side of the discharge flow path,
The storage unit is
An inlet through which the fluid flows in from the upstream side of the discharge passage;
An outlet from which the fluid stored in the storage portion flows out to the downstream side of the discharge flow path;
An inclined portion in which a radial cross-sectional area continuously decreases from the outlet toward the downstream side of the discharge flow path;
The piston according to any one of claims 1 to 6.

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