JP4290598B2 - Piston cooling system - Google Patents

Description

  The present invention relates to a piston cooling device, and more particularly to a device for cooling a piston of an internal combustion engine.

  Conventionally, piston cooling devices for preventing piston seizure and the like have been used in internal combustion engines such as diesel engines and gasoline engines. For example, in Patent Document 1, an annular cooling passage is provided in a piston, oil is injected from a jet nozzle into a supply port, oil is supplied into the cooling passage, and the oil is discharged from a discharge port to cool the piston. An apparatus is disclosed.

Japanese Utility Model Publication No.59-68124

However, in the piston cooling device of Patent Document 1, oil once discharged from the cooling passage may flow back into the cooling passage again from the discharge port as the piston descends. In this case, the backflowed oil prevents the oil supplied to the cooling passage and traveling toward the discharge port from being discharged, making it difficult for the oil to be discharged from the cooling passage. As a result, it becomes difficult to supply new oil having a lower temperature than the oil in the cooling passage into the cooling passage, and the cooling efficiency is lowered.
The present invention has been made to solve such problems, and an object thereof is to provide a piston cooling device capable of improving the cooling efficiency.

  A piston cooling device according to the present invention includes an annular cooling passage formed in a piston, an oil supply port and an oil discharge port communicating with the cooling passage, respectively, and injects oil from the jet nozzle toward the oil supply port. In the piston cooling device that supplies oil into the cooling passage and discharges it from the oil discharge port, it is arranged in the cooling passage near the oil discharge port and prevents backflow of oil from the oil discharge port into the cooling passage. Backflow prevention means is provided.

  The oil once discharged from the cooling passage tries to flow backward from the oil discharge port into the cooling passage as the piston descends, etc., but this oil is prevented by the backflow prevention means arranged in the cooling passage near the oil discharge port. Backflow into the cooling passage is prevented.

As a backflow prevention means, an oil blocking wall member is formed in the vicinity of the inner wall surface of the cooling passage facing the communicating portion between the oil discharge port and the cooling passage so as to block the oil flowing from the oil discharge port into the cooling passage. can do. Further, when the oil discharge port communicates with the cooling passage in a substantially T-shape, oil blocking wall members are formed in the cooling passages located on both sides of the communication portion between the oil discharge port and the cooling passage. It is preferable that
Also, as a backflow prevention means, an oil retaining gap that temporarily holds oil that is about to flow into the cooling passage from the oil discharge port, on the inner wall surface of the cooling passage facing the communicating portion between the oil discharge port and the cooling passage. A part can also be formed.

  According to the present invention, the backflow prevention means for preventing the backflow of oil from the oil discharge port into the cooling passage is disposed in the cooling passage near the oil discharge port. Backflow of oil into the cooling passage is prevented, and oil can be easily discharged from the cooling passage. As a result, new oil can be smoothly supplied into the cooling passage, and the cooling efficiency can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a partial cross-sectional view of an engine equipped with a piston cooling apparatus according to Embodiment 1 of the present invention. This piston cooling device is for cooling pistons of internal combustion engines such as diesel engines and gasoline engines. A piston 2 is slidably disposed in a cylinder block 1 of the engine. A hollow portion 2 a is formed in the piston 2 so as to open to the crank chamber 3 of the cylinder block 1 at its lower end. An annular cooling passage 4 is formed at the head of the piston 2. An oil supply port 5 is communicated downward to a predetermined portion of the cooling passage 4 so as to be orthogonal to the cooling passage 4 and at a position spaced apart from the oil supply port 5 by about 180 degrees with respect to the central axis of the piston 2. An oil discharge port 6 communicates downward with the cooling passage 4 so as to be orthogonal to the cooling passage 4. The oil supply port 5 and the oil discharge port 6 are open to the hollow portion 2a of the piston 2 at the lower ends thereof.

  A jet nozzle 7 for injecting cooling oil (lubricating oil) into the oil supply port 5 and supplying the oil into the cooling passage 4 is provided on the inner wall surface of the crank chamber 3 of the cylinder block 1. Oriented and arranged. The jet nozzle 7 is connected to an oil pressure pump (not shown) for supplying oil to the nozzle 7. The piston 2 is connected to a crankshaft (not shown) via a connecting rod 8, and the crankshaft is rotated by the reciprocating motion.

As shown in FIG. 2, the oil discharge port 6 communicates with the cooling passage 4 in a substantially T shape, and is inside the cooling passage 4 located on both sides of the communication portion 6 a between the oil discharge port 6 and the cooling passage 4. A pair of oil blocking wall members 9 and 10 are formed on the ceiling surface 4a so as to protrude from each other at a predetermined interval. These wall members 9 and 10 have upright surfaces 9a and 10a opposite to each other, and gently inclined surfaces 9b and 10b located on the opposite sides, respectively. Here, the angle formed by each of the upright surfaces 9a and 10a with respect to the ceiling surface 4a is such that the oil R that is going to flow backward from the oil discharge port 6 into the cooling passage 4 as shown by the broken line arrow in FIG. It is preferable to set a value close to a right angle as much as possible. Further, the angle formed by each of the inclined surfaces 9b and 10b with respect to the ceiling surface 4a does not hinder the progress of the oil S flowing in the cooling passage 4 toward the oil discharge port 6 as indicated by solid arrows in FIG. Is preferably set to a small value.
The cooling passage 4, the oil supply port 5, the oil discharge port 6, the jet nozzle 7, the oil pressure feed pump (not shown), and the oil blocking wall members 9 and 10 constitute the piston cooling device of the present invention.

  Next, the operation of the piston cooling apparatus according to Embodiment 1 of the present invention will be described. When cooling oil is pumped from an oil pump (not shown) to the jet nozzle 7 and injected from the jet nozzle 7 to the oil supply port 5, the oil S flows into the annular cooling passage 4 from the oil supply port 5. Then, they are divided into left and right, flow in the cooling passage 4, rejoin in the vicinity of the oil discharge port 6 of the cooling passage 4, and are discharged from the oil discharge port 6. Thereby, the piston 2 is cooled.

  Here, the oil once discharged from the inside of the cooling passage 4 flows back into the cooling passage 4 from the oil discharge port 6 as the piston 2 descends, and spreads into the cooling passage 4 through the ceiling surface 4a. However, the oil R is blocked by the upright surfaces 9 a and 10 a of the oil blocking wall members 9 and 10, thereby preventing the oil R from flowing back into the cooling passage 4. Accordingly, troubles such as interference with the oil S in which the oil R flows in the forward direction, that is, the oil S flowing in the cooling passage 4 toward the oil discharge port 6 and hindering the progress of the oil S are prevented. The oil S can be easily discharged from. As a result, new oil having a low temperature can be smoothly supplied into the cooling passage 4 regardless of the operation of the piston 2, thereby improving the cooling efficiency.

Further, even if the amount of oil injected from the jet nozzle 7 is reduced, new oil can be smoothly circulated in the cooling passage 4 and a good piston cooling effect can be obtained. A small-capacity pump can be used as the pump, and the fuel efficiency of the entire engine can be improved.
Further, since the oil blocking wall members 9 and 10 have gentle inclined surfaces 9b and 10b on the opposite side of the upright surfaces 9a and 10a, the forward direction flows in the cooling passage 4 toward the oil discharge port 6. The oil S can be efficiently discharged from the oil discharge port 6 without being blocked by the wall members 9 and 10.

  In the first embodiment described above, the size and shape of the oil blocking wall members 9 and 10, the installation position on the ceiling surface 4 a, etc. are the amount of oil supplied into the cooling passage 4, the shape of the cooling passage 4, It is preferable to adjust appropriately according to the volume, the assumed operating condition of the internal combustion engine, the amount of oil R that is going to flow backward from the oil discharge port 6 into the cooling passage 4 and the like.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The piston cooling device according to the second embodiment is the same as the piston cooling device according to the first embodiment shown in FIG. 1, except that the oil retaining gap is used as the backflow prevention means of the present invention instead of the oil blocking wall members 9 and 10. The part 21 is formed. That is, in the ceiling surface 4 a of the cooling passage 4, an oil retaining gap portion 21 that is recessed in the upper part of the ceiling surface 4 a is formed at a location facing the communication portion 6 a between the oil supply port 6 and the cooling passage 4. ing.

  When the oil once discharged from the cooling passage 4 flows back into the cooling passage 4 from the oil discharge port 6 as the piston 2 descends, and the like, it spreads into the cooling passage 4 along the ceiling surface 4a. The oil R is accommodated and held in the oil holding gap 21, thereby preventing backflow of the oil R into the cooling passage 4. Accordingly, problems such as the oil R interfering with the forward oil S flowing in the cooling passage 4 toward the oil discharge port 6 to prevent the oil S from proceeding are prevented, and the oil S can be easily removed from the cooling passage 4. Can be discharged. Therefore, as in the first embodiment, new oil having a low temperature can be smoothly supplied into the cooling passage 4 to improve the cooling efficiency.

  In the second embodiment described above, the volume and shape of the oil retaining gap 21 and the installation position on the ceiling surface 4a are the amount of oil supplied into the cooling passage 4, the shape and volume of the cooling passage 4, the internal combustion It is preferable to adjust appropriately according to the assumed operating conditions of the engine, the amount of oil R that tends to flow back into the cooling passage 4 from the oil discharge port 6, and the like.

1 is a partial cross-sectional view of an engine equipped with a piston cooling device according to Embodiment 1 of the present invention. 2 is an enlarged cross-sectional view showing a structure in the vicinity of an oil discharge port in Embodiment 1. FIG. 6 is an enlarged cross-sectional view showing a structure in the vicinity of an oil discharge port in Embodiment 2. FIG.

Explanation of symbols

  1 Cylinder block, 2 piston, 2a hollow part, 3 crank chamber, 4 cooling passage, 4a ceiling surface, 5 oil supply port, 6 oil discharge port, 6a communicating part, 7 jet nozzle, 8 connecting rod, 9, 10 For oil shut off Wall member, 9a, 10a Upright surface, 9b, 10b Inclined surface, 21 Oil retaining gap, S Forward oil, R Backflow oil.

Claims (4)

An annular cooling passage formed in the piston and an oil supply port and an oil discharge port respectively communicating with the cooling passage are provided, and oil is injected into the cooling passage by jetting oil from the jet nozzle toward the oil supply port. In the piston cooling device that supplies and discharges from the oil outlet,
A piston cooling device comprising a backflow preventing means disposed in a cooling passage in the vicinity of the oil discharge port and preventing backflow of oil from the oil discharge port into the cooling passage.   The backflow prevention means is formed to protrude in the vicinity of the inner wall surface of the cooling passage facing the communication portion between the oil discharge port and the cooling passage, and for oil blocking to block the oil flowing from the oil discharge port into the cooling passage. The piston cooling device according to claim 1, wherein the piston cooling device is a wall member.   The oil discharge port communicates with the cooling passage in a substantially T shape, and the oil blocking wall member is formed in each of the cooling passages located on both sides of the communication portion between the oil discharge port and the cooling passage. 2. The piston cooling device according to 2.   The backflow preventing means is formed on the inner wall surface of the cooling passage facing the communicating portion between the oil discharge port and the cooling passage, and temporarily holds oil that is about to flow into the cooling passage from the oil discharge port. The piston cooling device according to claim 1, wherein the piston cooling device is an air gap.

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