JPS6210456A - Piston of reciprocating type engine - Google Patents

Abstract

PURPOSE:To improve flow performance and cooling performance of a cooling medium and durability of a piston, by a method wherein an incoming and outgoing member for the cooling medium is placed to the lower part of a piston crown, and plural incoming cylinders for the cooling medium are concentrically situated to their respective cooling holes through an incoming passage for the cooling medium. CONSTITUTION:A cooling medium enters an incoming passage 22a through an incoming passage 21a, and is respectively distributed to incoming cylinders 17, and is injected to the final terminal of each cooling hole 16 to make a U-turn at the terminal. After the cooling medium flows through the whole of each cooling hole 16 to provide full cooling function, the cooling medium is discharged through outgoing passages 23b and 21b by means of the base end part of each cooling hole 16. In which case, an incoming and outgoing member 12, having the incoming passage 22a and the outgoing passage 23b, is independently disposed to the lower part of a piston crown 11, the incoming cylinders 17 are respectively connected to the incoming and outgoing member 12, and the incoming cylinders 17 are concentrically disposed in their respective cooling holes 16. This enables improvement of flow performance and cooling performance and durability of a piston.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reciprocating engine piston that has high reliability and can withstand high temperature and high pressure engine working media.

(Prior Art) Pistons used in reciprocating engines generally operate while in contact with high temperature and high pressure working media, and in such cases, it is necessary to have a structure that can withstand high pressure and to properly maintain this structure. A cooling mechanism is required to keep the temperature at a reasonable temperature.

For example, in the case of an internal combustion engine, the piston operates in contact with combustion gas, so stress from this gas pressure acts, and the temperature of the upper part of the piston that comes into contact with combustion gas becomes relatively high. Thermal stress also acts.

Therefore, in such a case, it is necessary to form an appropriate cooling space inside the piston and introduce a suitable cooling medium such as water or oil into this space for cooling.

Figure 3 shows an example of a piston used in a conventional diesel engine, where (1) is the piston crown, (1α) is the lip provided radially inside the piston crown, (2) is the internal hardware, and (3) is the piston crown. ) is a piston rod, (4) is a skirt, and (5) is a connecting bolt, and the arrows in the figure schematically indicate the flow direction of the cooling medium.

Generally, the thicker the wall thickness of each part constituting the piston crown (1), for example, the wall thickness t1 on the upper surface side (ceiling surface) and the wall thickness t2 on the side surface side (side wall) shown in FIG. Although the stress is reduced, the cooling effect deteriorates and the overall temperature level increases, and the thermal stress caused by temperature non-uniformity also increases, so it is difficult to adopt an appropriate structure. It becomes necessary.

For example, as shown in Fig. 3, radial ribs (1α) that support the upper surface (ceiling surface) are arranged inside the piston crown (1), and the upper surface (
The structure reduces the stress caused by the gas pressure on the ceiling (ceiling surface) and at the same time uses the ribs (1α) to increase the cooling area and improve the cooling effect.

(Problems with the Prior Art) In the piston of a conventional reciprocating engine, the cooling medium introduced into the piston behaves in an extremely complex manner, so it is necessary to accurately predict its behavior in advance to find the one that requires the most cooling. It is difficult to efficiently cool the parts that need to be cooled.

In addition, the structure using the lip shown in the example above also acts as a restraint against thermal distortion caused by uneven temperature, so there is also the possibility that high thermal stress will occur in the lip itself. Reduces stress caused by gas pressure,
At the same time, it is difficult to select a structure that is convenient for both purposes, such as keeping its own thermal stress low.

However, in order to improve the thermal efficiency of the engine, it is expected that the pressure and temperature of the working medium will continue to increase, and the above-mentioned difficulties will further increase.

(Objective of the Invention, Means for Solving Problems) The present invention was developed in order to solve the above-mentioned problems, and includes a cooling medium introduction passage and a discharge passage provided at the lower part of the piston crown. Separate introduction and discharge members are provided,
A plurality of cooling holes are provided in the piston crown so as to be close to the top surface or the side surface from the lower surface side and communicate with the discharge passage, and a plurality of cooling holes are provided concentrically and concentrically from the introduction passage to each of the cooling holes. It is characterized by a configuration in which a plurality of introduction tubes for the cooling medium are provided up to the vicinity of the end of the hole, and a separate introduction/discharge member equipped with a cooling medium introduction passage and a discharge passage is provided at the lower part of the piston crown, and the said discharge A plurality of cooling holes communicating with the passages are arranged from the lower surface side of the piston crown close to the upper surface or side surface thereof, and cooling medium is supplied from the introduction passage concentrically into each cooling hole and near the end of the hole. By providing the introduction tube, the consistency of the flow path of the cooling medium inside the piston crown improves the flow performance and cooling performance, and the separate formation of the introduction/discharge member and each introduction tube improves their performance. A reciprocating engine that significantly reduces the occurrence of thermal stress and eliminates the effect on the piston crown, significantly reducing the occurrence of thermal stress on the piston crown, significantly improving durability and reliability, and eliminating the above problems. to provide pistons.

(Example) Figure 1 (A) (B) K shows an example of the present invention.
In the figure, αυ is the piston crown, α is the piston rod, Q4) is the skirt connected to the piston rod α3, and a plurality of connecting bolts α9 are connected to the piston rod a3 and the skirt) (1, 4).
The piston crown (11) is connected to the piston crown (11).

Further, a cooling medium introduction passage (22α) and a discharge passage (23b) are provided at the bottom of the piston crown aυ.
A separate introducing/discharging member (hardware) α3 is fitted and provided, and is provided close to the upper surface (11α) or side surface (11b) from the lower surface side of the piston crown C[1]. A plurality of cooling holes (Lυ) are arranged and communicated with the discharge passage (23b), and an introduction/discharge member α
Each of the cooling holes σ communicates with the introduction passage (22α) of No. 2.
The structure is such that a plurality of cooling medium introduction tubes αη are provided concentrically in each of the holes up to the vicinity of the end of the hole.

The introduction passage (22α) is communicated with an introduction passage (21α) provided in the piston rod holder, and a cooling medium such as water or oil supplied by an appropriate well-known supply circulation mechanism (not shown) is passed through the introduction passage. (21α) and the introduction passage (
22α) is distributed into each introduction tube αη, the water is ejected from the tip thereof, makes a U-turn, and is supplied into each cooling hole ae from the end of the hole.
The cooling medium that has passed through the cooling hole α0 enters the common discharge passage (23b) from the base end of each cooling hole α0, and then enters the discharge passage (21b) provided in the center of the piston rod 03
The refrigerant path (in the direction of the arrow) is configured to circulate the refrigerant to the outside of the piston through the piston.

The shape and arrangement of the cooling holes α■ are as close as possible to the top surface (11α) or the side surface (11b) of the piston crown 0υ, so as to improve the cooling performance of the top surface and side surface of the piston crown αυ, and to reduce the generation of thermal stress as much as possible. It can be formed not only by machining but also by casting. The cross-sectional shape of each cooling hole (1G) can be formed into a circular, polygonal, or other suitable cross-section.

In addition, the introduction passage (22α) of the introduction/discharge member C1z
, the discharge passage (23b) and these passages and the introduction tube (17
1. The path between the cooling hole αe and the cooling hole αe is not limited to the illustrated example.

Furthermore, as in the second embodiment shown in FIG. 2, the cross section perpendicular to the piston axis at the piston crown 0υ is formed into an annular shape, and a plurality of cooling holes are formed in four groups arranged concentrically. , a plurality of said introduction tubes (I7) in each cooling hole □□□
It is also possible to have a configuration in which .

(Function) Since the embodiment of the present invention has the above-described configuration, the cooling medium such as water or oil from the known cooling medium supply circulation mechanism (not shown) is supplied from the introduction passage (21α) to (22
α) and each introduction tube αD from the introduction passage (22α).
At the same time, it is ejected from each introduction pipe (17) to the end of each cooling hole (16, 26), made a U-turn, and distributed throughout each cooling hole (16, 26). After exerting its cooling function, the cooling medium is discharged and circulated from the base end of each cooling hole (16, 26) through the discharge passage (23αX21b), so that the flow of the cooling medium becomes a consistent path within each cooling hole. The cooling medium is evenly distributed and supplied, the top and side surfaces of the piston crown are cooled extremely effectively, eliminating variations in cooling, and the flow rate and velocity of the cooling medium can be reliably controlled by the introduction pressure. It is easy to accurately predict the cooling effect in advance, the cooling performance and its reliability are significantly improved, and the generation of thermal stress is significantly reduced.

Furthermore, an introduction/discharge member ryr equipped with an introduction passage (22α) and a discharge passage (236): a separate piston crown αυ
Each introducing tube [17] is arranged at the lower part of the introducing/discharging member circle, and each introducing tube [17] has a cooling hole (16, 2).
6) Because they are arranged concentrically within the
Since the temperature of z and each introduction cylinder ση is low, the occurrence of thermal stress thereon is significantly reduced and does not cause the occurrence of thermal stress on the piston crown aυ.

In addition, the above-mentioned configuration allows for a wide range of freedom in selecting the material of the piston crown, the shape and dimensions of the cooling holes and introduction cylinder, the properties and flow rate of the cooling medium, etc., resulting in an overall economical piston. be done.

(Effects of the Invention) As described above, the present invention provides a separate introduction/discharge member α2 having a cooling medium introduction passage (22α) and a discharge passage (23h) at the lower part of the piston crown αυ, and the piston crown αυ A plurality of cooling holes (16, 26) are provided close to the upper surface (11α) or the side surface (11b) from the lower surface side and communicate with the discharge passage (23b), and the introduction passage (22α) Since a plurality of cooling medium introduction tubes aη are provided concentrically in each of the cooling holes (16, 26) up to the vicinity of the end of the hole, the consistency of the cooling medium flow path inside the piston crown improves the flow performance. Cooling can be adjusted freely and cooling performance has been significantly improved.
By forming the discharge member and each inlet pipe separately, they are kept at a relatively low temperature, the generation of thermal stress is significantly reduced, and there is no effect on the piston crown, and the generation of thermal stress on the piston crown is significantly reduced. The durability and reliability of the piston are significantly improved, and the piston has a wide range of freedom in structural selection, making it possible to provide a reliable piston at low cost.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

FIG. 1(A) is a longitudinal sectional view showing one embodiment of the present invention.
Figure (B) shows the cross sections of the nx-m part, IV-IV part, and V-V part of Figure 1.
FIG. 2 is a cross-sectional view of a piston crown portion showing a second embodiment of the cooling hole, and FIG. 3 is a partial vertical cross-sectional view of a conventional example. 11: Piston crown 11α: Top surface 11h: Side surface 12:
Introducing/discharging member 16.26: Cooling hole 17: Introducing tube 2
2α: Introduction passage 23h: Discharge passage Sub-agent Patent attorney Shige Okamoto 2 people outside the text Figure 2 30 Procedural amendment July 1985 25r3

Claims (1)

[Claims] A separate introduction/discharge member having a cooling medium introduction passage and a discharge passage is provided at the lower part of the piston crown, and is provided in the piston crown from the lower surface side approaching the upper surface or the side surface and communicating with the discharge passage. A reciprocating engine characterized in that a plurality of cooling holes are arranged, and a plurality of introduction tubes for the cooling medium are provided concentrically from the introduction passage to each of the cooling holes and extending to near the end of the hole. piston.