Lubricating device for engine

Abstract

A lubricating device for an engine is provided. A first opening part penetrates a first partition wall separating a crank chamber and an oil sump chamber. A second opening part penetrates a second partition wall separating the crank chamber and a valve drive chamber. In a lubricating device for an engine, when the pressure in the crank chamber is positive, gas in the crank chamber is injected into the oil sump chamber through the first opening part and impacts oil, thus generating mist oil in the oil sump chamber, and mist oil in the crank chamber passes through the second opening part and is supplied to the valve drive chamber, whereas when the pressure in the crank chamber is negative, mist oil in the oil sump chamber passes through the first opening part and is supplied to the crank chamber.

What is claimed is: 
     
         1 . A lubricating device for an engine, comprising:
 a crank chamber, a pressure in which varies as a piston moves up and down;   an oil sump chamber which is disposed below the crank chamber and that stores a lubricating oil;   a valve drive chamber which is disposed on a side of the crank chamber and that accommodates drive components of each valve mechanism for intake and exhaust;   a first partition wall that separates the crank chamber and the oil sump chamber;   a second partition wall that separates the crank chamber and the valve drive chamber;   a first opening part that penetrates the first partition wall and provides communication between the crank chamber and the oil sump chamber; and   a second opening part that penetrates the second partition wall and provides communication between the crank chamber and the valve drive chamber,   wherein, in the case in which a pressure in the crank chamber is a positive pressure, a gas in the crank chamber is injected into the oil sump chamber through the first opening part and impacts an oil in the oil sump chamber thereby to generate a mist oil in the oil sump chamber, and a mist oil in the crank chamber passes through the second opening part and is supplied to the valve drive chamber, and   in the case in which the pressure in the crank chamber is a negative pressure, the mist oil in the oil sump chamber passes through the first opening part, and is supplied to the crank chamber.   
     
     
         2 . The lubricating device for an engine according to  claim 1 ,
 wherein the first opening part is positioned in a projection plane of the piston in the first partition wall.   
     
     
         3 . The lubricating device for an engine according to  claim 1 ,
 wherein an opening area of the first opening part is within a range of from 3% up to 40% of a cross-sectional area of the piston.   
     
     
         4 . The lubricating device for an engine according to  claim 1 ,
 wherein a flow velocity of the gas injected through the first opening part into the oil sump chamber and blown onto an oil surface in the oil sump chamber is within a range of from 1,000 cm/s up to 10,000 cm/s.   
     
     
         5 . The lubricating device for an engine according to  claim 1 ,
 wherein the first partition wall has a tubular section that projects downward from a lower surface of the first partition wall such that the tubular section surrounds the first opening part.   
     
     
         6 . The lubricating device for an engine according to  claim 1 ,
 wherein a bearing that rotatably supports a crank shaft is provided in the second opening part, and   the bearing is an open ball bearing that allows passage of the mist oil.