JP2009299620A - Piston assembly method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology improving assemblability of a piston without causing enlargement of an engine. <P>SOLUTION: This invention is materialized as a method for assembling a piston including piston rings to a cylinder block including a cylinder bore. The cylinder bore opens to a cylinder head side and a lower case side. The piston rings are formed in such a manner that outer diameters under no load condition are larger than an inner diameter of the cylinder bore. The assembly method includes a process for setting a sleeve tool formed in a cylindrical shape of which one end expands in the cylinder bore in such a manner that the expanded end projects out of the opening at the lower case side, a process for aligning the piston to the cylinder bore to oppose to the opening at the lower case side, a process for pushing in the piston into the cylinder bore from the lower case side opening while drawing out the sleeve tool from the cylinder head side opening, and a process for completely drawing out the sleeve tool from the cylinder head side opening. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for assembling a piston to a cylinder block. In particular, the present invention relates to a technique for improving workability when a piston to which a piston ring is attached is stored in a cylinder bore of a cylinder block.

  When assembling the piston engine, the piston to which the piston ring is attached is stored in the cylinder bore of the cylinder block. A general piston ring is formed so that the outer diameter in an unloaded state is larger than the inner diameter of the cylinder bore. When the piston with the piston ring attached is housed in the cylinder bore, the outer surface of the piston ring is pressed against the inner surface of the cylinder bore by an elastic restoring force. In order to store the piston to which the piston ring is attached in the cylinder bore, the piston must be inserted into the cylinder bore while reducing the diameter of the piston ring.

  Patent Document 1 discloses a technique in which a tapered portion is formed at the end of a cylinder bore, the piston ring is reduced in diameter by a reaction force from the tapered portion when the piston is pushed in, and the piston is accommodated in the cylinder bore. Has been. In Patent Document 2, a jig having a tapered portion is set in the opening on the lower case side of the cylinder bore, the piston ring is reduced in diameter by a reaction force from the tapered portion when the piston is pushed in, and the piston is moved to the cylinder bore. A technique for storing in a container is disclosed.

Japanese Utility Model Publication No. 55-41513 JP 2002-46082 A

  In the technique of Patent Document 1, the cylinder block must be formed high enough to form the tapered portion at the end of the cylinder bore. If the cylinder block is formed higher, the engine becomes larger and the weight of the engine also increases.

  In the technique of Patent Document 2, after the piston is stored in the cylinder bore, the jig used to reduce the diameter of the piston ring must be removed from the opening on the lower case side. If the piston is already assembled with the crankshaft by the connecting rod before storing it in the cylinder bore, the jig must be removed with care so as not to interfere with the crankshaft and connecting rod existing near the opening on the lower case side. I must. When the piston is already assembled with the crankshaft by the connecting rod before being housed in the cylinder bore, and the crankshaft is already assembled with the lower case, the opening on the lower case side is closed when the piston is housed in the cylinder bore. From this state, it is difficult to remove the jig used to reduce the diameter of the piston ring, and the workability of assembling the piston is poor.

  The present invention solves the above problems. The present invention provides a technique for improving the assembly of a piston without causing an increase in size of the engine.

  The present invention is embodied as a method of assembling a piston having a piston ring to a cylinder block having a cylinder bore. The cylinder bores are opened on the cylinder head side and the lower case side, respectively. The piston ring is formed so that an outer diameter in an unloaded state is larger than an inner diameter of the cylinder bore. The assembling method includes a step of setting the sleeve jig formed in a cylindrical shape whose diameter is enlarged at one end to the cylinder bore so that the diameter-expanded end protrudes from the opening on the lower case side, and the opening on the lower case side. The step of aligning the piston with the cylinder bore, the step of pushing the piston into the cylinder bore from the opening on the lower case side while pulling out the sleeve jig from the opening on the cylinder head side, and the sleeve jig completely pulling out from the opening on the cylinder head side It has a process.

  In the above assembling method, when the piston is pushed into the cylinder bore while pulling out the sleeve jig, the diameter-enlarged portion of the sleeve jig is reduced according to the inner diameter of the cylinder bore and is surrounded by the diameter-enlarged portion of the sleeve jig. The diameter of the piston ring is also reduced. Thus, the piston can be accommodated in the cylinder bore while reducing the diameter of the piston ring. In the above assembling method, after the piston is housed in the cylinder bore, the sleeve jig used for reducing the diameter of the piston ring is extracted from the opening on the cylinder head side. In the above assembling method, it is not necessary to form a tapered portion in the cylinder bore, and the engine is not enlarged. In addition, the sleeve jig used to reduce the diameter of the piston ring can be removed from the opening on the cylinder head side, and the workability is good.

  The above assembly method is particularly useful when the piston is already assembled to the crankshaft by the connecting rod and the crankshaft is already assembled to the lower case.

  When the piston is already assembled to the crankshaft and the crankshaft is already assembled to the lower case, the opening on the lower case side is closed by the lower case when the piston is stored in the cylinder bore. In this state, it is difficult to remove the jig used to reduce the diameter of the piston ring from the opening on the lower case side. However, in the above assembling method, since the sleeve jig used for reducing the diameter of the piston ring is removed from the opening on the cylinder head side, no problem occurs even if the opening on the lower case side is closed. Before the piston is housed in the cylinder bore, the piston can be assembled to the crankshaft, and further the crankshaft can be assembled to the lower case. The assembly of the engine is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the assembly | attachment property of a piston can be improved, without causing the enlargement of an engine.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) A piston assembling method in an inline engine.

  As shown in FIG. 1, the engine 100 of this embodiment includes a cylinder head 102, a cylinder block 104, and a lower case 106. The engine 100 is an in-line four-cylinder engine and includes four pistons 108 arranged side by side in the depth direction of FIG. The cylinder block 104 is formed with four cylinder bores 110 that house the pistons 108. The cylinder bores 110 are opened on the cylinder head 102 side and the lower case 106 side, respectively. Each piston 108 is connected to a crankshaft 114 by a corresponding connecting rod 112. The crankshaft 114 is rotatably held by the cap 116 and the lower case 106. In engine 100, combustion chamber 118 is formed by cylinder head 102, cylinder block 104, and piston 108. In the engine 100, a crank chamber 120 is formed by the cylinder block 104, the lower case 106, and the piston 108.

  Compression rings 122 and 124 and an oil ring 126 are attached to each piston 108. In the present specification, the compression rings 122 and 124 and the oil ring 126 are collectively referred to as a piston ring. The compression rings 122 and 124 and the oil ring 126 are fitted in a ring groove formed in the piston 108. The compression rings 122 and 124 and the oil ring 126 are formed so that the outer diameter in the no-load state is larger than the inner diameter of the cylinder bore 110. When the piston 108 is housed in the cylinder bore 110, the outer surfaces of the compression rings 122 and 124 and the oil ring 126 are pressed against the inner surface of the cylinder bore 110 by an elastic restoring force.

  In this embodiment, when the engine 100 is assembled, first, the piston 108 is integrally assembled to the crankshaft 114 by the connecting rod 112. Then, the crankshaft 114 is assembled to the cap 116 and the lower case 106. Hereinafter, an assembly of the piston 108, the connecting rod 112, the crankshaft 114, the cap 116, and the lower case 106 is also referred to as a moving module 128. Then, after the moving module 128 is assembled to the cylinder block 104, the cylinder head 102 is assembled to the cylinder block 104.

  In order to assemble the moving module 128 to the cylinder block 104, with the compression rings 122 and 124 and the oil ring 126 reduced in diameter, the piston 108 is inserted from the opening on the lower case 106 side of the cylinder bore 110, and the piston 108 is inserted into the cylinder bore 110. Must be stored. The procedure for assembling the moving module 128 to the cylinder block 104 will be described below with reference to FIGS.

  First, as shown in FIG. 2, the sleeve jig 200 is inserted from the opening on the lower case 106 side of the cylinder bore 110, and the sleeve jig 200 is set in the cylinder bore 110. As shown in FIG. 3, the sleeve jig 200 is a cylindrical thin metal member having a tip that has an enlarged diameter. As shown in FIG. 2, the sleeve jig 200 is set in the cylinder bore 110 such that the enlarged diameter portion 202 at the tip protrudes from the opening on the lower case 106 side.

  Next, as shown in FIG. 4, the cylinder block 104 and the piston 108 are aligned so that the center axis of the cylinder bore 110 and the center axis of the piston 108 coincide with each other and the piston 108 faces the opening of the cylinder bore 110 on the lower case 106 side. I do.

  Next, as shown in FIG. 5, the moving module 128 is pushed up, and the piston 108 is inserted into the cylinder bore 110 from the opening on the lower case 106 side. In accordance with this, the sleeve jig 200 is pulled out from the opening on the cylinder head 102 side. As a result, the diameter-enlarged portion 202 of the sleeve jig 200 is reduced in diameter in accordance with the inner diameter of the cylinder bore 110, and the compression rings 122 and 124 and the oil ring 126 surrounded by the diameter-enlarged portion 202 of the sleeve jig 200 are also reduced. The diameter will continue. The entire piston 108 is accommodated in the cylinder bore 110 while reducing the diameters of the compression rings 122 and 124 and the oil ring 126.

  Next, as shown in FIG. 6, the sleeve jig 200 is completely pulled out from the opening on the cylinder head 102 side of the cylinder bore 110. Thereby, the assembly work of the cylinder block 104 and the moving module 128 is completed.

  According to the assembling method of the present embodiment, it is not necessary to form tapered portions for reducing the diameters of the compression rings 122 and 124 and the oil ring 126 at the end of the cylinder bore 110. Therefore, it is not necessary to form the cylinder block 104 redundantly high, and the engine 100 can be reduced in size and weight.

  In the assembling method of this embodiment, since the sleeve jig 200 is removed from the opening on the cylinder head 102 side after the piston 108 is stored in the cylinder bore 110, the opening on the lower case 106 side is closed when the piston 108 is stored. It doesn't matter if it is done. Therefore, before assembling to the cylinder block 104, the piston 108, the connecting rod 112, the crankshaft 114, the cap 116, and the lower case 106 can be assembled in advance as the moving module 128. The workability of assembling the engine 100 is improved.

  As the shape of the sleeve jig 200, in addition to the shape shown in FIG. 3, for example, a notch may be formed in the enlarged diameter portion 202 as shown in FIG. When the notch is formed in the enlarged diameter portion 202 in this way, when the sleeve jig 200 is pulled out from the cylinder bore 110, the enlarged diameter portion 202 easily becomes the inner diameter of the cylinder bore 110, and the workability is further improved.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

FIG. 1 is a longitudinal sectional view of the engine 100. FIG. 2 is a view showing a state where the sleeve jig 200 is set in the cylinder bore 110 of the cylinder block 104. FIG. 3 is a view showing a schematic shape of the sleeve jig 200. FIG. 4 is a view showing how the piston 108 is aligned with the cylinder bore 110. FIG. 5 is a view showing a state where the moving module 128 is pushed up while the sleeve jig 200 is pulled out. FIG. 6 is a view showing a state where the sleeve jig 200 is completely pulled out. FIG. 7 is a view showing a schematic shape of a modified example of the sleeve jig 200.

Explanation of symbols

100 Engine 102 Cylinder head 104 Cylinder block 106 Lower case 108 Piston 110 Cylinder bore 112 Connecting rod 114 Crankshaft 116 Cap 118 Combustion chamber 120 Crank chamber 122, 124 Compression ring 126 Oil ring 128 Moving module 200 Sleeve jig 202 Expanded portion

Claims (2)

A method of assembling a piston having a piston ring to a cylinder block having a cylinder bore,
The cylinder bores are open on the cylinder head side and the lower case side,
The piston ring is formed so that the outer diameter in the no-load state is larger than the inner diameter of the cylinder bore.
The assembly method is
A step of setting a sleeve jig formed in a cylindrical shape whose one end is enlarged in a cylinder bore so that the enlarged end protrudes from the opening on the lower case side;
Aligning the piston with the cylinder bore so as to face the opening on the lower case side;
Pushing the piston into the cylinder bore from the opening on the lower case side while pulling out the sleeve jig from the opening on the cylinder head side;
An assembly method comprising a step of completely pulling out the sleeve jig from the opening on the cylinder head side.   The assembly method according to claim 1, wherein the piston is already assembled to the crankshaft by a connecting rod, and the crankshaft is already assembled to the lower case.

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