Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
2000-08-29
2001-12-25
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
Reexamination Certificate
active
06332443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lubricating oil supplying structure for a crankshaft, and in particular to a lubricating oil supplying structure for a crankshaft, which is provided to a connecting rod and which can smoothly supply a lubricating oil to a connecting rod bearing contacting a crank pin.
2. Description of the Related Art
In general, as shown in
FIGS. 6 and 7
, a crankshaft
51
of, for instance, a straight four cylinder engine
50
is supported and fixed within a crank case
53
by a crank journal support structure
55
. The crank journal support structure
55
is constructed such that a plurality of crank journal bearings
67
of semi-circular shape in a aide view are provided at lower end portions of plural crank journal supporting wall portions
66
within the crank case
53
of a cylinder block
52
, and the crank journal bearing
67
are coupled respectively to bearing caps
56
of semi-circular shape in a cross view.
On the other hand, as shown in
FIGS. 7 and 8
, a piston
59
is axially supported through a piston pin
68
by a small end side
58
of the connecting rod
57
, and a big end side
60
of the connecting rod
57
is axially supported through a connecting rod bearing
62
by a crank pin
61
of the crankshaft
51
.
The crankshaft
51
is provided with a lubricating oil supplying passage inside thereof unillustrated, and a lubricating oil pressured by an oil pump is supplied to a crank journal bearing
67
contacting the crank journal
54
and the connecting rod bearing
62
supporting the connecting rod
57
to the crank pin
61
, thereby lubricating the crank journal
54
and the crank journal bearing
67
, as well as the crank pin
61
and the connecting rod bearing
62
.
That is, the crank journal bearing
67
is provided with an oil groove (not shown), to which the lubricating oil pressured by the oil pump is supplied. The lubricating oil spread out from the oil groove lubricates between the crank journal
54
and the crank journal bearing
67
. The lubricating oil supplying passage is provided between the crank journal
54
and the crank pin
61
, one end of which is opened to an oil groove of the crank journal bearing
55
, and the other end of which is opened at a surface portion of the crank pin
61
to a slidingly contacting surface
63
of the connecting rod bearing
62
with the crank pin
61
to which the connecting rod
57
is mounted.
Therefore, the lubricating oil entering the oil groove provided in the crank journal bearing
67
by the action of the oil pump lubricates the inner circumferential surface
65
of the crank journal bearing
67
. The lubricating oil also reaches the crank pin
61
through the lubricating oil passage from the oil groove, and spread to the slidingly contacting surface
63
of the connecting rod bearing
62
to lubricate the slidingly contacting surface
63
of the connecting rod bearing
62
with the crank pin
61
.
Besides, a combustion load within the cylinder acts the most largest in a cylinder axial direction to the crank journal bearing
67
through the piston
59
and the connecting rod
57
. That is, the generated combustion load acts the most largely to the bearing cap
56
located at the lower and portion of the bearing as shown in FIG.
6
.
In this case, for example, if the oil groove is provided in the bearing inner circumferential surface
65
at the bearing cap
56
, the pressure receiving surface of the bearing inner circumferential surface
65
where the combustion load acts is reduced by the provision of the oil groove. Consequently, the combustion load against which the crank journal bearing
67
can bear is made small, requiring an upper limitation to the generated combustion load.
Therefore, in designing an engine, in general, a required engine power is first determined, and then a combustion pressure necessary for the engine power and an engine revolution speed are calculated, and a bearing width necessary for the combustion pressure is determined. In this case, as mentioned above, if it is necessary to inevitably provide an oil groove in a portion receiving the combustion load, the bearing width dimension in that portion must be made large. Consequently, the bearing width is increased, and the engine weight is enlarged correspondingly. This is disadvantageous in designing the engine, for inviting the increases of the bearing width and the engine weight.
For this reason, conventionally, an oil groove is normally provided in the crank journal bearing
67
not over the entire circumference of the bearings and which is located at a portion where the generated combustion load does not act directly. For example, in the case where a cylinder arrangement of an engine is straight or V-type, the oil groove is typically provided partially in the crank journal bearing
67
of the crank case to avoid such an instance that it is provided in the crank journal bearing
67
of the bearing cap
56
.
When the oil groove is provided in the entire circumference of the crank journal bearing
67
, the lubricating oil supplying passage is constantly opened to the oil groove regardless of the rotational angle of the crank journal
54
, and accordingly the lubricating oil supplied by the oil pump can constantly supplied to the slidingly contacting surface
63
of the connecting rod bearing
62
with the crank pin
61
. However, when the oil groove is provided partially in the crank journal bearing
67
, an end portion of the lubricating oil supplying passage is not always opened to the oil groove depending on a certain rotational angle.
In this case, since the connecting rod
57
is a member for transmitting the vertical movement of the piston
59
to the crank journal
54
through the crank pin
61
, and if consideration is given to the magnitude of the combustion load acting on the coupled portion between the big and
60
and the crank pin
61
, it is desirable to constantly supply the lubricating oil in-between the connecting rod bearing
62
and the crank pin
61
for lubrication.
SUMMARY OF THE INVENTION
Accordingly, aspects of the present invention is to provide a lubricating oil supplying structure for a crankshaft, which can supply lubricating oil to a connecting rod bearing provided in a connecting rod so as to perform excellent lubrication between the connecting rod and a crank pin, and which can support a predetermined combustion load of an engine.
Accordingly, the other aspect of the present invention is, in addition to the object of the first aspect, to provide a lubricating oil supplying structure for a crankshaft, which can supply more lubricating oil to a connecting rod bearing provided in a connecting rod to perform excellent lubrication between the connecting rod and the crank pin.
An object of the other aspect of the present invention is, in addition to the object of the second aspect, to provide a lubricating oil supplying structure for a crankshaft, in which a complicated lubricating oil supplying passage is not required within a crankshaft.
The other aspect of the present invention is, in addition to the object of the third aspect, to provide a lubricating oil supplying structure for a crankshaft, which can continuously supply lubricating oil from an oil groove portion of a crank journal bearing to a connecting rod bearing.
The other aspect of the present invention is, in addition to the object of the second aspect, to provide a lubricating oil supplying structure for a crankshaft, which can maintain a pressure-resistive load acting on a connecting rod bearing at a predetermined magnitude.
The other aspect of the present invention is, in addition to the object of the first aspect, to provide a lubricating oil supplying structure for a crankshaft, which can smoothly supply lubricating oil to a portion where the largest combustion load acts in a connecting rod.
According to the first aspect of the present invention, a lubricating oil supplying structure for a crankshaft
19
, which is provided within the crankshaft
19
disposed wit
McMahon Marguerite
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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