JPH08338304A - Liquid-cooled type piston in reciprocating type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid-cooled piston in a reciprocating internal combustion engine provided with a cooling device bringing further excellent cooling action. SOLUTION: A liquid-cooled piston has a cooling chamber 15 provided with a return passage 6 for refrigerant led into the cooling chamber 15 through one of feed passages 30, 31, 32 and a plurality of injection nozzles 18. The return passage 6 extends into a piston rod 5 and has a vent pipe line inside. The vent pipe line 10 extends into the cooling chamber 15 and is provided at a part of the return passage 6 inside the piston rod 5. A portion, extending into the return passage 6, of the vent pipe line 10 has its terminal ends inside the piston rod 5 so as not to come in contact with air separately from the return passage 6. Gas in the return passage 6 flows into the vent pipe line 10 and then flows into the cooling chamber 15 through the vent pipe line 10. Pressure reduction in the cooling chamber 15 is impeded, and the outflow of refrigerant to the return passage 6 is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-cooled piston in a reciprocating internal combustion engine having a cooling chamber formed of a liquid refrigerant return passage provided in a piston rod.

[0002]

2. Description of the Related Art Material loss such as wear of the upper part of a piston in an internal combustion engine is mainly caused by high temperature. In recent years, in the reciprocating internal combustion engine, insufficient cooling of the piston is one of the factors that bring about the limitation of the output. Therefore, the improvement in efficiency in the piston cooling device is extremely important in the reciprocating internal combustion engine in order to obtain the highest output performance and reliability in use.

A liquid-cooled piston in a reciprocating internal combustion engine having a reciprocating internal combustion engine cooling chamber consisting of a coolant return passage provided in a piston rod is disclosed in Japanese Patent Application No. 4-3.
No. 9384. In the piston, a cooling chamber is provided in the upper portion of the piston in the vicinity of the end face of the piston on the combustion chamber side, and the injection nozzle injects cooling oil into the cooling chamber to cool the piston. The injected oil is discharged from the cooling chamber via the return passage. The return flow path extends the entire length of the interior of the piston rod and opens at the end of the piston rod remote from the cooling chamber into a separate oil outflow channel provided in the crosshead connected to the piston rod. With the piston rod arranged vertically below the cooling chamber, the return flow gradient causes an oil return flow due to the action of the specific gravity of the oil collected in the cooling chamber. Air is supplied to the cooling chamber through a ventilation pipe line that connects the air in the engine and the cooling chamber, whereby oil flows out from the cooling chamber. In this device, the ventilation conduit is provided in the oil return passage. One end of the ventilation pipe projects into the cooling chamber, and the other end separated from the cooling chamber merges with an oil flow passage provided separately from the oil outflow passage in the crosshead to come into contact with air.

[0004]

It has been clarified that the maximum inflow amount of the liquid refrigerant in the piston cooling by the above device is excessively limited, which limits the development of the internal combustion engine aiming at higher performance. .

It is an object of the present invention to provide a liquid-cooled piston in a reciprocating internal combustion engine equipped with a cooling device with a better cooling effect.

[0006]

This object is achieved by the device according to the invention. The device of the present invention is characterized in that a ventilation channel is provided in the return channel projecting into the piston cooling chamber on the piston side, and the ventilation channel is accommodated in a part of the return channel in the piston rod. Have. Claim 2
The following relates to further features that work effectively in the present invention.

The liquid cooled piston of the present invention has a cooling chamber with a return flow path for the refrigerant introduced into the cooling chamber.
The return passage is provided in the piston rod, and the ventilation pipe is provided in the return passage. The ventilation line extends into the cooling chamber at the end of the piston and is provided in the piston rod in a part of the return flow path. In the ventilation line,
The portion extending into the return channel has an end within the piston rod. That is, the vent line does not open into the crosshead and does not contact air separately from the return flow path.
The flow of refrigerant in the return flow path is affected by the function of the vent line. That is, the gas in the return channel flows into the ventilation pipe, and further flows into the cooling chamber via the ventilation pipe. This prevents the pressure drop in the cooling chamber and prevents the refrigerant from flowing out to the return passage.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described with reference to FIG. One embodiment of the piston of the present invention is shown in FIG. The main elements of the piston are the piston top 1, the injection plate 4 and the piston skirt 3. The upper part 1 of the piston is
The upper end 25 of the piston facing the combustion chamber in an internal combustion engine
Have. The piston has a symmetrical shape with respect to the axis 50. The piston upper part 1 and the injection plate 4 are both
It is adjacent to the piston cooling chamber 15. The piston upper part 1, the piston skirt 3 and the injection plate 4 are connected to the piston rod 5 at their peripheral portions. A plurality of cooling holes 17 whose upper ends are closed are formed in the piston upper portion 1, and each cooling hole 17 is directed from the cooling chamber 15 toward the piston surface 25, that is, toward the piston surface 25. The piston rod 5 is connected to the crosshead 8 at the end portion separated from the piston.

During operation of the internal combustion engine, the piston moves with the upper part 1 on top of the piston rod 5, preferably along an axis 50 extending substantially perpendicular to the surface of the earth. The cooling chamber 15 forms part of the cooling liquid circuit. For example, a cooling liquid such as oil or water flows into the cooling chamber 15 by the injection device. The cooling liquid flows into the pipe line 30 provided in the piston rod 5 on the crosshead 8 side. Next, the refrigerant passes from the pipe line 30 through the passage 31 having an annular shape in a sectional view and reaches the cavity 32 between the injection plate 4 and the piston rod 5,
It is ejected from a plurality of nozzles 18 supported by the ejection plate 4. The region of the piston upper part 1 that is closest to the piston surface 25 receives the strongest heat load when the internal combustion engine is operating. The nozzles 18 are preferably arranged such that the injected cooling liquid reaches the area. Particularly effective cooling action is by injection cooling, that is, the wall of the cooling hole 17,
Alternatively, it can be obtained by injecting a cooling liquid on the wall of the cooling chamber 15. The pipe 30, the passage 31, the cavity 32, and the nozzle 18 constitute the injection device of the present invention.

The above-mentioned injection functions in two ways. As one function, the surface to be cooled contacts the refrigerant. The temperature of the refrigerant matches the liquid temperature in the refrigerant circuit, and the refrigerant becomes turbulent due to injection. Thereby, the heat conduction between the surface to be cooled and the refrigerant is improved to an optimum state. As another function, in most cases, a cleaning effect can be obtained by injecting a refrigerant onto the end surface of the piston. For example, refrigerant oil readily forms a residue that adheres to the end face of the piston when the piston reaches a certain temperature during operation. The residue reduces the thermal conductivity between the end face and the cooling liquid, which further raises the temperature of the piston and accelerates the oil residue deposition action. The residue depositing action in the cooling holes 17 is particularly problematic. Removal of this deposit requires complicated and expensive work. However, by injecting the refrigerant onto the end surface to be cooled, it is possible to prevent the accumulation of the residue.

A refrigerant return passage (hereinafter referred to as “return passage”) 6 is provided to let the refrigerant flow out of the cooling chamber 15. Preferably, the return passage 6 is the piston rod 5
Extending along the central axis line 50, opening in the cooling chamber 15 and the opening 21 of the injection plate 4, and connected to the return line of the refrigerant circuit on the crosshead 8 side. The injection plate 4 is inclined toward the opening 21 on the cooling chamber 15 side in order to most efficiently flow the refrigerant into the return passage 6. Further, in the vicinity of the opening 21 to the cooling chamber 15, the return passage 6 is designed to have a smaller diameter as the distance from the cooling chamber 15 increases. In order to simplify the manufacturing, it is preferable that the return channel 6 has a circular shape in a plan sectional view. However, no matter what shape it has in plan view,
The function of the return channel 6 is reliably guaranteed.

The refrigerant in the cooling chamber 15 is basically 2
Exerts one cooling effect. One of the cooling effects is the effect of injection cooling in which the refrigerant is directly injected from the nozzle 18 onto the surface to be cooled. The splash cooling that exerts another cooling effect is performed by splashing the liquid refrigerant collected in the cooling chamber 15 after injection on the periphery along the moving direction of the piston during operation of the internal combustion engine. In order to optimize the cooling action, on the one hand, as much refrigerant as possible should be supplied to the cooling chamber 15
Have to pass through. On the other hand,
It is necessary to keep the heat conduction between the surface to be cooled and the refrigerant as good as possible. If an excessive amount of refrigerant is present in the cooling chamber 15, the cooling action will be reduced. For example, when the injection nozzle 18 is covered with the coolant, the injection efficiency of the coolant is reduced and the injection action, that is, the spray cooling action is also reduced. Further, it is known that if the content volume of the refrigerant in the cooling chamber 15 becomes excessive, the splash cooling effect is reduced. Splash cooling is possible only when a minimum amount of cooling liquid is collected in the cooling chamber 15. Cooling chamber 15 for optimal cooling
In order not to deviate the amount of the refrigerant partially recovered into the predetermined range between the maximum and minimum allowable values, the cooling chamber 15
The piston of the present invention is designed to control the flow of refrigerant through it. Therefore, the flow rate of the refrigerant flowing out from the cooling chamber 15 per unit time is regulated, and an amount of the refrigerant suitable for performing the best cooling is injected into the cooling chamber 15 under the various conditions described above.

The ventilation conduit 10 is fixed at a predetermined position with respect to the return passage 6 by the metal plate supporting members 40 and 41.
The design of is an important factor that determines the flow rate of the refrigerant flowing out from the cooling chamber 15 per unit time.

In the present invention, the return flow path 6 is the ventilation line 1.
Along with zero, the outflow of the refrigerant is controlled. This control is performed in the cooling chamber 1
5 and the return channel 6 and the return channel 6 in the crosshead 8.
This is performed by equalizing the pressure of the gas in the return line of the refrigerant circuit adjacent to. In order to optimize the volume of the return flow path 6, when designing the ventilation conduit 10, it is necessary to take into consideration various effects that show the opposite tendency to each other in correlation with the individual parameters, and do not cancel these opposite effects. So it is necessary to choose the optimal compromise conclusion.

The preferred range of the length of the ventilation conduit 10 extending in the return passage 6 is determined in consideration of the following mutually opposing actions. One of the actions is that the fluid resistance of the return passage 6 increases when the length of the ventilation pipe 10 is increased. That is, the refrigerant mainly flows out between the outer peripheral surface of the ventilation conduit 10 and the inner peripheral surface of the return passage 6, and the refrigerant flows through the ventilation conduit 1
Friction occurs with the outer peripheral surface of zero. On the contrary, if it is assumed that the ventilation pipe line 10 is not provided as an extreme example, a refrigerant pool is formed and the entire area of the opening 21 of the injection plate 4 is covered. When the refrigerant pool is formed, gas does not flow into the cooling chamber 15 from the return channel 6, so that it becomes difficult to equalize the pressures of the cooling chamber 15 and the return channel 6. The effect of reducing the amount of refrigerant outflow is reduced by increasing the length of the ventilation conduit 10 extending in the return passage 6, and the formation of a refrigerant pool that covers and closes the opening 21 is also prevented. The ventilation pipe line 10 includes the crosshead 8 and the cooling chamber 15.
The flow of the refrigerant in the return passage 6 flowing between the end of the ventilation pipe 10 and the end of the ventilation pipe 10 is determined so as to ensure the gas permeability. In consideration of both of them, the optimum range is determined for the length of the ventilation conduit 10 extending in the return passage 6. The applicant of the present application obtained the following numerical values as a result of the experiment. That is, the optimum range of the length of the ventilation conduit 10 in the return passage 6 is 10% to 90% of the length of the return passage 6, and preferably 15% to 50% of the length of the return passage 6. Up to%. The detailed numerical value is influenced by other parameters such as the cross-sectional area or shape of the ventilation pipe 10.

The ideal range of the cross-sectional area of the ventilation conduit 10 is determined in consideration of the following two requirements. That is, as a first requirement, the cross-sectional area of the ventilation conduit 10 can be made to be as large as possible for the space between the outer wall surface of the ventilation conduit 10 and the inner wall surface of the return passage 6 for the refrigerant outflow. It should be as small as possible. As a second requirement, it is necessary to make the cross-sectional area as large as possible in order to improve the gas inflow efficiency into the cooling chamber 15. The cross-sectional area of the ventilation line 10 is determined in consideration of these two requirements. Again, as a result of experiments, the applicant of the present application has found that the optimum cross-sectional area of the ventilation pipe 10 is in the range of 20% to 70% of the cross-sectional area of the return flow passage 6, preferably the cut-off of the return flow passage 6. It was concluded that it is in the range of 25% to 60% of the area. The detailed numerical value is influenced by other parameters such as the length or shape of the ventilation conduit 10.

A suitable range of the length of the ventilation pipe 10 projecting into the cooling chamber 15 is determined in consideration of the following two requirements. That is, the first requirement is that the cooling chamber 1 of the ventilation conduit 10 is
If the portion projecting to 5 is too short, a considerable proportion of the refrigerant will flow out through the ventilation line 10, which will result in a cooling chamber 1
The point that the amount of gas supplied to 5 decreases is mentioned. The second requirement is that if the portion of the ventilation pipe 10 protruding into the cooling chamber 15 is too long and the end of the ventilation pipe 10 near the cooling chamber 15 is too close to the wall of the cooling chamber 15, the ventilation pipe 10 The inflow of refrigerant into 10 is obviously blocked, but the inflow of gas into the cooling chamber 15 is also restricted. The applicant of the present application obtained the following results as a result of the experiment. That is, the optimum length "a" from the wall of the cooling chamber 15 to the end of the ventilation duct 10 on the cooling chamber 15 side is the distance "h" in the longitudinal direction of the ventilation duct 10 in the cooling chamber 15. It is in the range of 10% to 90% of "h", and preferably in the range of 15% to 65% of "h".

In addition to the above parameters, the maximum amount of refrigerant flowing out through the return passage 6 is influenced by the movement frequency of the piston in the axial direction of the piston rod 5 when the internal combustion engine is operating. Since the pool of refrigerant splashes around the axial direction of the piston rod 5, the refrigerant flows out exclusively through the return flow path 6 during a certain piston movement period. The applicant of the present application discovered the following as a result of the experiment. That is, while the amount of refrigerant flowing out from the cooling chamber 15 is obviously reduced due to the movement of the piston, the volume of the return flow passage 6 accompanying the movement of the piston is more sensitive than that when the piston is stationary. It is affected by the dimensions of the ventilation line 10. Therefore, it is important to design the ventilation pipe line 10 in an optimum state in consideration of the movement of the piston. The optimum range described above for the dimensions of the vent line 10 accommodates the movement of the piston.

The shape of the vent line 10 is not critical to the invention, for example, the cross section of the vent line 10 can have any desired shape or contour. Vent line 10 having a circular cross section is merely a preferred embodiment. Pipe line 1
0 is available in most cases and does not need to be manufactured. The pipe line 10 is also suitable for use in a piston having a circular outflow passage. A circular vent line 10 mounted so as to be concentric with the return channel 6 is particularly effective. In this way, the method of mounting the device concentrically with the return flow path 6 is suitable for the shape of the flow of the refrigerant in the cooling chamber 15 having a symmetrical shape about the axis 50. In addition, the shape of the cross section of the ventilation conduit 10 does not have to be constant.

As explained above, the liquid-cooled piston of the present invention is provided with the return passage 6 for the refrigerant introduced into the cooling chamber 15 through the supply passages 30, 31, 32 and the nozzle 18. It has a chamber 15. The return passage 6 extends in the piston rod 5, and a ventilation pipe 10 is provided in the return passage 6. The ventilation pipe 10 projects inside the piston cooling chamber 15 on the piston side, and is provided only in a part of the return passage 6 in the piston rod 5. The portion provided in the return passage 6 of the ventilation pipe 10 is
It is housed in the piston rod 5 and does not come into contact with air separately from the return passage 6. The gas in the return channel 6 flows into the ventilation conduit 10 and passes through the ventilation conduit 10 to cool the cooling chamber 1.
When flowing into 5, the pressure in the cooling chamber 15 decreases, and the cooling liquid can be prevented from flowing out from the return passage 6. In order to avoid such a pressure drop, the flow of the refrigerant in the return passage 6 is controlled by the ventilation pipe line 10. The ventilation conduit 10 functions to optimize the flow rate of the refrigerant flowing through the cooling chamber 15.

[0021]

As described above, according to the piston of the present invention, the gas in the return passage flows into the ventilation pipe, and further flows into the cooling chamber via the ventilation pipe, so that the pressure in the cooling chamber decreases. Is prevented and the refrigerant is prevented from flowing out to the return flow path. As a result, there is an effect that the flow rate of the refrigerant in the cooling device can be increased, the cooling action in the device can be improved, and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a piston having a cooling chamber, a liquid refrigerant injection device, a return passage and a ventilation pipe.

[Explanation of symbols]

5 ... Piston rod, 6 ... Refrigerant return passage, 10 ... Venting pipe, 15 ... Cooling chamber, 17 ... Cooling hole, 18 ... Nozzle, 3
0 ... Pipe line, 31 ... Passage, 32 ... Cavity (18, 30-32
Is composed of the injection device).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location F01P 3/10 F01P 3/10 A F16J 1/08 F16J 1/08 1/09 1/09 1 / 12 1/12 (72) Inventor Marc Sparni Switzerland Zeher-8400 Wintertool General Guisant-Strasse 41

Claims (10)

[Claims] 1. A liquid-cooled piston comprising a cooling chamber (15) for a piston reciprocating internal combustion engine having a refrigerant return passage (6) in a piston rod (5), said return passage (6). The inside of 6) is provided with a ventilation pipe (10) which projects toward the piston and extends into the cooling chamber (15) of the piston, and extends over a part of the return passage (6) in the piston rod (5). A liquid-cooled piston that is characterized. 2. The length of the portion of the ventilation conduit (10) extending into the return passage (6) is 10% to 90% of the length of the return passage (1), preferably the return passage. The piston according to claim 1, which is 15% to 50% of the length of (1). 3. The cross-sectional area of the ventilation conduit (10) is 20% to 70% of the cross-sectional area of the return channel (6), preferably 25% -60% of the cross-sectional area of the return channel (6). %, The piston according to claim 1 or 2. 4. A cooling chamber (15) for the ventilation line (10).
The distance between the side end and the cooling chamber (15) is equal to that of the ventilation pipe (10).
Of the distance the cooling chamber (15) extends in the longitudinal direction of
% To 90%, preferably 15% to 6 of the distance that the cooling chamber (15) extends in the longitudinal direction of the ventilation pipe (10).
It is 5%, The piston of any one of Claim 1 thru | or 3 characterized by the above-mentioned. 5. The return conduit (6) has an opening (21) extending into the cooling chamber (15) such that the return conduit (6) has a smaller diameter with distance from the cooling chamber (15). The piston according to any one of claims 1 to 4, which is characterized. 6. The vent line (10) is a return channel (6).
Piston according to any one of claims 1 to 5, characterized in that it is arranged concentrically with said return flow path (6). 7. An injection device (30, 31, 32, 18) for injecting a refrigerant into the cooling chamber (15), as claimed in any one of claims 1 to 6. piston. 8. Piston according to any one of the preceding claims, characterized in that the cooling chamber (15) comprises at least one cooling hole (17). 9. The injection device (30, 31, 32, 1)
Piston according to claim 7 or 8, characterized in that 8) has at least one nozzle for injecting a refrigerant into at least one of the cooling hole (17) and the wall of the cooling chamber (15). 10. An internal combustion engine comprising the piston according to claim 1. Description: