JPH0676643U - Combustion engine pistons - Google Patents

Abstract

(57) [Summary] [Purpose] The amount of relative displacement between the crown and the skirt is reduced to reduce the amount of posture control of the crown, which improves stability of the posture of the crown and blow-by with the followability of the piston. A combustion engine piston that reduces gas and oil consumption. [Structure] A pair of cylindrical skirt holding members press-fitted into the pin holes of the crown portion are rotatably fitted into the skirt portion pin holes, and a piston pin pivotally supporting the connecting rod small end is used as a crown pin. The cylindrical skirt holding member was press-fitted into the hole and fitted into the pin hole of the skirt portion, and was inserted into the hollow portion of the cylindrical skirt holding member, and the skirt portion was coupled and supported to the outer periphery of the pin boss of the crown portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston of a combustion engine, and more particularly to a two-body type piston in which a crown portion and a skirt portion of each separated piston are coaxially supported together by a piston pin together with a connecting rod small end.

[0002]

[Prior art]

 FIG. 2 is a sectional view of a conventional two-body type piston. As shown in FIG. 2, in a two-body type piston in which the crown portion 1 and the skirt portion 2 are separated, the pin provided on the pin boss 3 of the crown portion 1 The clearance between the inner peripheral surface of the hole 13 and the outer peripheral surface of the piston pin 4 is a, the clearance between the inner peripheral surface of the pin hole 14 provided in the skirt portion 3 and the outer peripheral surface of the piston pin 4 is b, and the crown portion 1 When the distance between the lower end of the oil ring groove 11 and the upper end of the skirt 2 is L, it is necessary to allow for the variation of a + b as the range of L.

That is, in the above-mentioned conventional two-body type piston, after the position of the skirt portion 2 is determined in relation to the cylinder liner (not shown), the crown portion 1 is provided with an oil provided on the outer periphery thereof. It is possible to move up and down and left and right within the range of the distance L 2 = a + b between the lower end of the ring groove 11 and the upper end of the skirt 2, and the followability of the piston ring and the blow-by gas and oil consumption or piston slap accompanying it It causes problems such as noise.

Further, when assembling a two-body type piston in which the crown portion and the skirt portion are separated, each component forming the two-body type piston is set so as to be coaxial, and the piston pin is inserted into the pin hole of each component. There is also a problem that the assembly becomes complicated due to the insertion.

By the way, a piston of a two-body combustion engine in which a crown portion and a skirt portion of the piston are coaxially coupled and supported by a piston pin and a small end of the cathode, is disclosed in, for example, Japanese Patent Publication No. 61-1855. ing. In Japanese Patent Publication No. 61-1855, a crown portion and a skirt portion are separately structured, and a pair of bosses extending from the crown portion and the skirt portion are pivotally connected by a piston pin, and the crown portion and the skirt portion are connected. There is disclosed a combination type piston in which a gap for suppressing heat transfer is formed between the portions facing the seat portion.

[0006]

[Problems to be solved by the device]

 However, the one disclosed in Japanese Examined Patent Publication No. 61-1855 is a combination in which the crown portion and the skirt portion are separate structures and a gap for suppressing heat transfer is formed between the facing portions of the crown portion and the skirt portion. This is a type piston, and it is suggested to reduce the relative displacement between the crown and the skirt, reduce the amount of crown posture control performed by the skirt, and improve the stability of the crown posture. Is not available.

According to the present invention, the relative displacement between the skirt portion and the crown portion can be achieved only by the clearance between the inner peripheral surface of the pin hole of the skirt portion and the outer peripheral surface of the piston pin of the cylindrical skirt holding member into which the piston pin is press fitted. Compared with the conventional two-body type piston, the relative displacement between the crown part and the skirt part can be made smaller, and the amount of posture control of the crown part performed by the skirt part can be made smaller. It is possible to improve the stability of the posture of the engine, reduce the amount of blow-by gas and the amount of oil consumed due to the followability of the piston, and reduce the piston slap noise. It is intended to be provided.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, in the piston of the combustion engine according to the present invention, a pair of cylindrical skirt holding members press-fitted into the pin holes provided in the pin bosses of the crown are provided with skirt pin holes at both ends. The piston pin pivotally supporting the small end of the connecting rod is fitted in the hollow part of the cylindrical skirt holding member, and the skirt part is coupled and supported on the outer circumference of the pin boss of the crown part. Has been done.

Further, in the present invention, in the above means, the cylindrical skirt holding member does not deform when press-fitted into the pin hole of the crown portion, and is thin enough to hold the skirt portion when assembling the piston. It is assumed to be thick.

[0010]

[Action]

 To attach the skirt part and the connecting rod's small end to the crown part, first press the two cylindrical skirt holding members into the pin holes provided in the pin boss of the crown part, and then press the skirt to the outer end of each cylindrical skirt holding member. The pin hole provided in the portion is fitted and the skirt portion is rotatably and coaxially supported by the outer end portion of each cylindrical skirt holding member.

Then, the small size of the connecting rod is inserted from the pin hole of one of the skirts through the hollow part of the cylindrical skirt holding member so as to be inserted into the small end of the connecting rod placed in the middle part of each cylindrical skirt holding member. Insert the piston pin into the end, insert the piston pin into the hollow part of the cylindrical skirt holding member that is press-fitted into the pin hole provided in the pin boss of the other crown part, and use both ends of the piston pin with snap rings. Hold it, and assemble the crown, skirt, and connecting rod small end.

The relative displacement between the skirt portion and the crown portion is performed only by the clearance between the inner peripheral surface of the pin boss of the skirt portion and the outer peripheral surface of the cylindrical cart holding member into which the piston pin is fitted. Compared to a two-body piston, the relative displacement between the crown and skirt can be reduced, and the amount of crown posture control performed by the skirt can be reduced, improving the stability of the crown posture. Can be made.

Further, the relative displacement between the crown portion and the skirt portion is only the clearance between the inner peripheral surface of the pin hole of the crown portion and the outer peripheral surface of the cylindrical skirt holding member press-fitted into the pin hole provided in the skirt portion. Therefore, the amount of movement of the crown portion becomes small, and the amount of blow-by gas and the amount of oil consumed due to the followability of the piston are reduced, and at the same time the piston slap noise is reduced.

[0014]

【Example】

 Hereinafter, an embodiment of a piston of a combustion engine according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a piston of a combustion engine according to the present invention, and FIG. 2 is a side view of a piston of a conventional combustion engine. As shown in FIG. 1, the piston bosses 3 and 3 are inserted into and coupled to the pin holes 13 and 13 provided in the pin bosses 3 and 3 of the crown portion 1 of the piston having the combustion chamber 7 at the top. The small end 8 of the connecting rod 5 is rotatably supported between the pin holes 13, 13.

The outer diameter of the piston pin 4 is large enough to be inserted and connected to the pin holes 14 and 14 provided in the skirt portion 14, and the length thereof is the pin boss 2 of the crown portion 1. 2, the length between the snap rings 12, 12 provided on the outer ends of the pin holes 13, 13 provided on the piston pin 4, and the pin holes 14, provided on the skirt portion 2, at both ends of the piston pin 4, 14 are insert-coupled.

In the pin holes 13 and 13 provided in the pin bosses 3 and 3 at the lower part of the crown portion 1, a slight clearance a between the inner peripheral surface of the pin hole 13 and the outer peripheral surface of the piston pin 4 is eliminated. A cylindrical skirt holding member 6 is press-fitted in the skirt, and pin holes 14, 14 of the skirt portions 2, 2 are rotatably fitted and inserted into both outer ends of the cylindrical skirt holding member 6. The parts 2 and 2 are attached to the outer peripheral surface of the piston pin 4 via a cylindrical skirt holding member 6 so as not to fall off by the snap rings 12 and 12.

The inner diameters of the pin holes 13 and 13 provided in the pin bosses 3 and 3 at the lower portion of the crown portion 1 are reduced by the interference amount so that the cylindrical holding member 6 is press-fitted. The inner diameter of the provided pin hole is set to a size corresponding to a slight clearance b between the skirt portion and the outer diameter of the piston pin 4 because the skirt portions 2 and 2 are rotatably supported. .

The thickness of the cylindrical skirt holding member 6 is such that the cylindrical skirt holding member 6 does not receive the load of the skirt portion 2, so that the pin bosses 4 and 4 of the crown portion 1 are provided with pin holes. It is possible to press fit into the clearances a, a between the piston pins 4 and 13, and press the cylindrical skirt holding member 6 into the pin holes 13, 13 provided in the pin bosses 3, 3 under the crown portion 1. When the two-body type piston is assembled, the skirt portions 2 and 2 are not deformed at all times, and when the pin holes 14 of the skirt portion 2 are inserted into the outer periphery of the cylindrical skirt holding portion 6. It only needs to be held. The cylindrical skirt holding member 6 may be steel, cast steel or the like as long as it satisfies the above conditions.

To attach the skirt portions 2 and 2 and the small end 8 of the connecting rod 5 to the crown portion 1, first, two cylindrical skirt holding members are provided in the pin holes 13 and 13 provided in the pin bosses 3 and 3 of the crown portion 1. 6 are respectively press-fitted, the pin holes 14, 14 provided in the skirts 2, 2 are fitted into the outer ends of the respective cylindrical skirt holding members 6, and the skirts are held by the outer ends of the respective cylindrical skirt holding members 6. The parts 2 and 2 are rotatably supported coaxially.

The hollow portion of the cylindrical skirt holding member 6 is inserted from the pin hole 14 of the one skirt portion 2 so as to be inserted into the small end 8 of the connecting rod 5 placed in the intermediate portion of each cylindrical skirt holding member 6, 6. The piston pin 4 is inserted into the small end 8 of the connecting rod 5 through the pin, and the piston pin 4 is further press-fitted into the pin hole 13 formed in the pin boss 3 of the other crown portion 1 to hold the cylindrical skirt holding member 6 Then, both ends of the piston pin are held by the snap rings 12, 12, and the crown part 1, the skirt part 2, and the small end 8 of the connecting rod 5 are assembled.

It goes without saying that even a so-called combination piston in which the skirt portion 2 has a plurality of layers can be implemented within the range described in this embodiment. Reference numeral 9 is a first ring groove for mounting a piston ring, 10 is a second ring groove for mounting a piston ring, and 11 is an oil ring groove.

[0022]

[Effect of device]

 In the piston of the combustion engine according to the present invention, the pin holes of the skirt are rotatably fitted to both ends of a pair of cylindrical skirt holding members press-fitted into the pin holes provided in the pin boss of the crown. The piston pin that pivotally supports the small end of the connecting rod is inserted into the hollow portion of the cylindrical skirt holding member, and the skirt portion is coupled and supported on the outer circumference of the crown pin pin. Since the relative displacement between the skirt and the crown is performed only by the clearance between the inner peripheral surface of the pin hole and the outer peripheral surface of the cylindrical skirt holding member into which the piston pin is fitted, the crown is compared to the conventional two-body piston. The amount of relative displacement between the skirt and the skirt can be reduced, the amount of posture control of the crown portion performed by the skirt portion can be reduced, and the stability of the posture of the crown portion can be improved. To be an effect that it is.

Further, in the piston of the combustion engine according to the present invention, the pin holes of the skirt are rotatably attached to both ends of the pair of cylindrical skirt holding members press-fitted into the pin holes provided in the pin boss of the crown. The piston pin pivotally supporting the small end of the connecting rod is inserted into the hollow portion of the cylindrical skirt holding member, and the skirt portion is coupled and supported to the pin boss outer periphery of the crown portion. The relative displacement between the crown part and the skirt part is due only to the clearance between the crown part and the cylindrical skirt holding member that is inserted into the pin hole provided in the skirt part, and the movement amount of the crown part becomes small and the piston It is effective in reducing the amount of blow-by gas and the amount of oil consumed due to the followability and reducing the piston slap noise.

Further, in the piston of the combustion engine according to the present invention, a pair of cylindrical skirt holding members press-fitted into pin holes provided in the pin boss of the crown portion are rotatably provided with the pin holes of the skirt portion. Insert the piston pin that pivotally supports the small end of the connecting rod into the pin hole provided in the pin boss of the crown, and insert it into the hollow part of the cylindrical skirt holding member that is inserted into the pin hole of the skirt part. Since the skirt part is connected and supported to the outer circumference of the pin boss of the crown part, the two cylindrical skirt holding members are press-fitted into the pin holes provided in the pin boss of the crown part, and are inserted into the outer ends of the respective cylindrical skirt holding members. A pin hole provided in the skirt portion is fitted and the skirt portion is rotatably supported coaxially by the outer end portion of each cylindrical skirt holding member. So that the small end of the connecting rod is inserted from the pin hole of one skirt through the hollow part of the skirt holding member so that it will pass through the small end of the rod. The crown part, the skirt part, and the small end of the connecting rod can be assembled by inserting into the hollow part of the skirt holding member that is press-fitted, and any equipment changes can be made by the same process as the conventional piston assembly process. It has an effect that it can be assembled without any trouble.

Further, the cylindrical skirt holding member of the piston of the combustion engine according to the present invention does not deform when press-fitted into the pin hole of the crown portion, and can hold the skirt portion when the piston is assembled. Since the wall thickness is thin, the clearance between the outer peripheral surface of the cylindrical skirt support member press-fitted into the pin hole of the crown portion and the inner peripheral surface of the pin hole of the crown portion can be eliminated, and the crown portion and skirt portion can be eliminated. Assembling the three small ends of the connecting rod can be done in the same way as the conventional piston assembly process.

[Brief description of drawings]

1 is a sectional view showing an embodiment of a piston of a combustion engine according to the present invention.

FIG. 2 is a sectional view of a conventional two-body piston.

[Explanation of symbols]

 1 Crown part 2 Skirt part 3 Pin boss of crown part 4 Piston pin 5 Connecting rod 6 Cylindrical skirt holding member 7 Combustion chamber 8 Small end of connecting rod 13 Pin hole provided in pin boss of crown part 14 Pin hole provided in skirt part

Claims (2)

[Scope of utility model registration request] 1. A pin hole of a skirt portion is rotatably fitted into both ends of a pair of cylindrical skirt holding members press-fitted into a pin hole provided in a pin boss of a crown portion, and a small end of a connecting rod is attached. A piston for a combustion engine, wherein a pivotally supported piston pin is fitted and inserted in a hollow portion of the cylindrical skirt holding member, and the skirt portion is coupled and supported to an outer periphery of a pin boss of a crown portion. 2. The cylindrical skirt holding member has a wall thickness that is thin enough not to deform when the crown portion is press-fitted into the pin hole and to hold the skirt portion when assembling the piston. The piston of the combustion engine according to claim 1.