JPS6233426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for cooling a piston in a crosshead type internal combustion engine.

Internal combustion engines are divided into trunk piston type internal combustion engines in which the piston and crankshaft are directly connected by a connecting rod, and internal combustion engines in which a piston rod and crosshead pin are interposed between the piston and the connecting rod. It is classified as a crosshead type internal combustion engine in which the connecting rod is connected to the crankshaft. In general, the former is configured as a small to medium-sized and medium-high speed engine, and the latter is configured as a large, low-speed engine.

In either type, the area that requires the most attention in design is around the combustion chamber.In particular, the head of the piston becomes the ignition surface of the combustion chamber and is subjected to heat load and explosion pressure at the same time. This is where the most attention should be paid in terms of design and operation management.

Therefore, conventionally, in order to reduce the thermal load on the piston head, the strength of the piston head has been maintained by cooling the inside of the piston by circulating fresh water, oil, or the like.

However, in recent years, with the demand for more compact internal combustion engines, the single-cylinder output (horsepower per cylinder) has increased, and the heat load on the piston has become increasingly severe, making it no longer possible to circulate only fresh water or oil. The methods have become inadequate.

That is, increasing the amount of cooling water or cooling oil increases the supply pressure, requiring a special pump for the internal combustion engine.
In addition, in the case of fresh water cooling, as the flow rate increases, the cooling path inside the piston has a complicated shape.
Cavitation and erosion occur where the flow velocity changes. The amount of heat removed in oil-cooled locations is inferior to that in fresh water.

Because of the above-mentioned drawbacks, it has been recognized that in trunk piston type, four-cycle engines, the cooling effect can be improved by mixing gas into the cooling medium and using the stirring effect.

However, in an internal combustion engine with an intake valve at the head of the cylinder, the gas does not reach the area below the piston, so it is possible to attach the pipe that feeds the cooling medium and air into the piston directly to the bottom of the piston. However, in large crosshead-type internal combustion engines, the lower part of the piston communicates with the scavenging chamber, and for this reason, a stuffing box is provided as a seal to prevent the piston rod from merging into the crank chamber. , cooling inside the piston cannot be achieved by the same method as described above.

Incidentally, in a crosshead-type internal combustion engine, the applicant company of the present invention has developed a crosshead type internal combustion engine in which cooling oil is fed into the cooling chamber inside the piston through the inside of the crosshead pin and piston rod, and air is mixed into the cooling oil. We tried to send compressed air back into the flow of cooling oil from the piston-cooled cooling oil discharge passage sent out from the pin, but this made it difficult to mix the compressed air. Also, the cooling effect was not sufficient.

The present invention is intended to eliminate these drawbacks, and in a crosshead type internal combustion engine,
A passage for a cooling medium such as cooling oil or water, and a passage for mixing a gas such as air are provided in the piston rod, and the gas is mixed into the cooling medium in the cooling chamber inside the piston to stir the cooling medium. By increasing the cooling efficiency, it is possible to increase the cooling effect without increasing the pressure of the pump system that supplies the cooling medium.As a result, the high heat load is reduced, the single cylinder output is increased, and , which can extend the life of the piston.

Next, the present invention will be explained with reference to an embodiment shown in the drawings.

1 is a piston head, 2 is a piston stand, 3 is a piston skirt, 4 is a piston rod, 5 is a partition plate of a chamber 6 formed by the piston head 1 and the piston stand 2, and 7 is the piston head 1 and the piston stand 2. This is a set bolt that connects the piston rod 4 and the piston rod 4 at the same time. Piston head 1 and piston stand 2
A cooling chamber 8 was provided in the center between the two. Since the piston 9 is formed by the piston head 1, the piston stand 2, etc., the cooling chamber 8 is provided inside the piston 9. Reference numeral 10 denotes a hole provided in the piston rod 4 in the axial direction, and is a hole that penetrates between the upper and lower ends of the piston rod 4. Inside this hole 10, a double tube consisting of an outer tube 14 and an inner tube 15 is arranged so as to have three passages from the outside: an outer circumferential passage 11, an intermediate passage 12, and a central passage 13. The outer peripheral end surface of the outer tube 14 of the tube is connected to the piston rod 4.
The tips of the intermediate passage 12 and the center passage 13 were opened to the cooling chamber 8 inside the piston 9 while being in close contact with the inner surface of the piston stand 2 attached to the tip of the piston 9. The distal end surface of the outer tube 14 was made to substantially coincide with the bottom surface of the cooling chamber 8, and the distal end of the inner tube 15 was made to extend into the inside of the cooling chamber 8. Supports 16 are arranged at several locations in the circumferential direction between the outer tube 14 and the inner tube 15;
17 is a fixing ring provided at the lower end of the double pipe. The piston 9 side, which is the tip of the outer peripheral passage 11 inside the piston rod 4, is communicated with the bottom of the chamber 6 through several holes 18 provided in the piston stand 2, and is connected to the inside of the partition plate 5 of the chamber 6. were communicated with the outer periphery of the cooling chamber 8 through several holes 19.

The lower end of the piston rod 4 is connected to a crosshead pin 20 via a fixing ring 17. The crosshead pin 20 is provided with an inlet 21 and an outlet 22 for cooling medium in a direction perpendicular to the crankshaft. The cooling medium inlet 21 communicated with the lower end of the outer circumferential passage 11, and the lower end of the intermediate passage 12 communicated with a cooling medium outlet 22 provided in the crosshead pin 20. In the illustrated embodiment, a portion of the coolant injection passage 23 within the crosshead pin 20 is open to a portion of the outer circumferential surface of the crosshead pin 20;
Using oil as a cooling medium, the crosshead pin 2
It also serves as lubrication for the outer rotating part of the 0. However, when fresh water is used as the cooling medium, a part of the cooling medium injection passage 23 in the crosshead pin 20 is not released to the outer peripheral surface of the crosshead pin 20. Central passage 1 in inner tube 15
The lower end of the crosshead pin 3 communicated with a gas inlet 25 via a gas passage 24 provided within the crosshead pin 20. The cooling medium inlet 21 was connected to a cooling medium supply via a fixed tube and a telescopic tube (not shown). The cooling medium outlet 22 and the gas inlet 25 may remain open, or may be connected to a cooling medium recovery section and a gas supply source, respectively, via a fixed pipe and a telescopic pipe (not shown). 26 is a cylinder.

In the figure, the flow of the cooling medium is shown by a solid arrow, and the flow of gas is shown by a chain double-dashed arrow.

In the device configured in this manner, a cooling medium such as cooling oil is supplied from the inlet 21, passes through the outer circumferential passage 11, and enters the hole 1 formed in the piston base 2.
8 and reaches the chamber 6 of the piston head 1, where cooling of the piston 9 begins. The cooling medium passing through the chamber 6 reaches the cooling chamber 8 and removes heat from the inside of the piston head 1. That is, the head of the piston 9 is cooled by the chamber 6 and the cooling chamber 8. The heated cooling medium that performs the cooling action in the cooling chamber 8 passes through the intermediate passage 12, passes through the opening of the fixing ring 17, and passes through the crosshead pin 20.
It is discharged from the discharge port 22 of. While the cooling medium is supplied from the inlet 21, circulates within the piston rod 4 and the piston 9, and reaches the outlet 22, the piston 9 and the piston rod 4 repeat an explosive action and move up and down. Therefore, the cooling medium supplied to the inlet 21 is subjected to a pumping action by a telescopic tube (not shown), and when the piston 9 moves downward, the cooling medium becomes under positive pressure, and when the piston 9 moves upward, The inside of the piston 9 becomes a vacuum, and therefore the cooling medium becomes under negative pressure. By utilizing this effect, when the inside of the cooling chamber 8 in the piston 9 becomes negative pressure, the gas supplied from the gas inlet 25 can be easily supplied into the cooling chamber 8 through the central passage 13. , mixed into the cooling medium in the cooling chamber 8. In this case, the gas is ejected against the cooling medium in the cooling chamber 8, and the flow is reversed to the cooling medium which is about to flow into the intermediate passage 12 within the cooling chamber 8. Since gas is ejected from the central passage 13,
The gas is sufficiently mixed into the cooling medium in the cooling chamber 8, and the cooling medium is sufficiently stirred. Due to this stirring action, the cooling effect within the cooling chamber 8 is significantly improved, and the head of the piston 9 is sufficiently cooled.

Note that when the cooling medium becomes under positive pressure, it tends to flow into the center passage 13, intermediate passage 12, etc., but if the same lubricating oil used in the crank chamber is used as the cooling medium, There is no problem even if the cooling medium flows backward through the central passage 13 and the like. However, due to the stroke and diameter of the telescopic tube (not shown), it may not be possible to suck enough gas into the central passage 13. Just install a valve. Note that this check valve must be provided in order to prevent the piston cooling medium from entering the crankcase. Furthermore, if the amount of gas mixed in needs to be increased beyond that achieved by the self-pumping action, the gas can be forcibly mixed in from the gas inlet 25 using a gas supply pump or the like.

In addition, in the above-described embodiment, a double tube was provided in the piston rod 4, but this is not limited to a round tube. For example, two small-diameter pipes may be provided in parallel in the hole 10, or the hole 10 may be divided into three by using a partition plate.
It may be divided into two parts. In any case, the piston rod must be provided with two passages for the cooling medium, which communicate through the cooling chamber 8, and another passage for the gas supply, which is open into the cooling chamber. Good. In addition, the outer peripheral passage 11 and the central passage 1
3 as a cooling medium passage and intermediate passage 12 as a gas supply passage to further increase the agitation of the cooling medium within the cooling chamber 8.

As described above, in the present invention, the configuration as described in the claims is adopted, and the piston rod contains
A cooling medium passage and a gas supply passage are provided, and the gas is mixed with the cooling medium in the cooling chamber inside the piston.
Since the cooling medium is stirred, the cooling medium can be stirred extremely easily and sufficiently in the piston cooling section. Therefore, this stirring action increases the number of times and contact area between the heating part of the piston and the cooling medium, increasing the cooling effect and increasing the pressure of the pump system that supplies the cooling medium. Therefore, the head of the piston can be sufficiently cooled. Also,
As a result, the high heat load can be reduced, the single cylinder output can be increased, and the life of the piston can be extended.

[Brief explanation of the drawing]

The drawings show one embodiment of an apparatus for carrying out the method of the present invention, and FIG. 1 is a longitudinal sectional view, and FIG.
FIG. DESCRIPTION OF SYMBOLS 1... Piston head, 2... Piston stand, 4... Piston rod, 8... Cooling chamber, 9... Piston, 10...
Hole, 11...Outer circumferential passage, 12...Middle passage, 13...Center passage, 14...Outer tube, 15...Inner tube, 20...Crosshead pin, 21...Cooling medium inlet, 22...
Exhaust port, 25...Gas inlet, 26...Cylinder.

Claims (1)

[Scope of Claims] 1. In a cooling chamber inside the piston, a gas that is separately sent through the inside of the crosshead pin and the piston rod is added to the cooling medium that is sent into the cooling chamber through the inside of the crosshead pin and the piston rod. A method for cooling a piston in an internal combustion engine, in which a cooling medium is stirred in a cooling chamber inside the piston. 2. Three passages in the axial direction are provided inside the piston rod installed between the crosshead pin and the piston,
Two of the passages are communicated via a cooling chamber within the piston, and the ends of the two passages are communicated with a cooling medium inlet and an outlet provided in the crosshead pin, respectively, The tip of the other one of the three passages is opened into the cooling chamber inside the piston, and the other end of this passage is communicated with a gas inlet provided in the crosshead pin, so that the inside of the piston is A cooling device for a piston in an internal combustion engine that allows the cooling medium to be stirred by mixing gas with the cooling medium in a cooling chamber. 3. A hole in the axial direction is provided inside the piston rod attached to the crosshead pin, and a double pipe is arranged in this hole so as to have three passages: an outer circumferential passage, an intermediate passage, and a central passage; With the outer peripheral tip surface of the outer tube of this double tube in close contact with the inner surface of the piston attached to the tip of the piston rod, the tips of the intermediate passage and the center passage are opened to the cooling chamber inside the piston. , communicating a piston-side end of the outer circumferential passage inside the piston rod with a cooling chamber inside the piston;
The other ends of the outer circumferential passage and the intermediate passage are communicated with a cooling medium inlet and an outlet provided on a crosshead pin, respectively, and the other end of the center passage is communicated with a gas inlet provided on a crosshead pin. A piston cooling device for an internal combustion engine according to claim 2.