Sintered alloy valve guide and method of producing sintered alloy valve guide
AssigneeTpr Co., Ltd.
InventorsFumiya Ito, Shohtaroh Hara
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Abstract
The present invention addresses the problem of providing a sintered alloy valve guide capable of inhibiting valve adhesion even in a high-temperature environment. The problem can be solved by a sintered alloy valve guide impregnated with a lubricating oil including pores that are sealed on the valve guide outer circumferential surface. More particularly, the problem is solved by the sealing step of performing a sealing treatment of pores on the outer circumferential surface of a sintered body impregnated with a lubricating oil.
Claims9
A sintered alloy valve guide impregnated with a lubricating oil, comprising pores of a side arranged on a combustion chamber side in a lengthwise direction that are sealed on a valve guide outer circumferential surface,
- wherein the valve guide is formed from a single material, and
- when a cross-section of the valve guide is observed, a number of pores that have a depth of at least 20 μm and are open in a length of at least 20 μm on an outer circumferential surface is 18 or less in a 30 mm-long range of a portion that corresponds to the outer circumferential surface having sealed pores at the cross-section.
A method of producing a sintered alloy valve guide, the method comprising:
- a molding step of molding a raw material powder to obtain a molded body;
- a sintering step of sintering the molded body to obtain a sintered body;
- an impregnation step of impregnating a lubricating oil into the sintered body obtained in the previous step;
- and
- a sealing step of performing a sealing treatment of pores on an outer circumferential surface of the sintered body impregnated with the lubricating oil,
- wherein, when a cross-section of the valve guide is observed, a number of pores that have a depth of at least 20 μm and are open in a length of at least 20 μm on the outer circumferential surface is 18 or less in a 30 mm-long range of a portion that corresponds to the outer circumferential surface having sealed pores at the cross-section, and
- on the valve guide outer circumference surface, the pores of a side arranged on a combustion chamber side in the lengthwise direction are sealed.
Dependencies are inferred from the claim text.