Information
-
Patent Grant
-
6662771
-
Patent Number
6,662,771
-
Date Filed
Monday, September 17, 200123 years ago
-
Date Issued
Tuesday, December 16, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Denion; Thomas
- Chang; Ching
Agents
- Armstrong, Kratz, Quintos, Hanson & Brooks, LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 9015
- 123 9016
- 123 9017
- 123 9018
- 123 9033
- 123 9034
- 123 196 M
- 184 151
- 184 152
-
International Classifications
-
Abstract
Sprockets are fixed to ends of camshafts supported in a cylinder head via camshaft holders, and a timing chain is wrapped around these sprockets. An oil drain hole is provided for supplying relief oil of a hydraulic control valve to the timing chain, and an oil jet is provided for issuing a jet of oil at high pressure from the hydraulic control valve to the timing chain. When the engine is rotating at low speed oil is supplied only through the oil drain hole, and when the engine is rotating at high speed, oil is supplied through both the oil jet and the oil drain hole. The timing chain wrapped around the sprockets of the camshafts can thereby be reliably lubricated according to the operational state of the engine.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine in which a sprocket is fixed to one end of a camshaft and a timing chain is wrapped around the sprocket and, in particular, to a timing chain lubricating system therefor.
2. Description of the Related Art
A camshaft of an overhead camshaft type engine is driven by an arrangement in which a sprocket fixed to a shaft end of the camshaft is linked to a sprocket fixed to a shaft end of a crankshaft via a timing chain. A lubricating system for such a timing chain is known in Japanese Patent Application Laid-open No, 6-146838. The timing chain lubricating system disclosed in the above-mentioned application has an arrangement in which a relief valve is provided in an oil passage for supplying oil to a hydraulic tappet, and the section where the sprocket is meshed with the chain is lubricated with a jet of oil that issues from an oil jet that is integral with the relief valve,
In the above-mentioned conventional arrangement, since the oil jet can lubricate only one position of the timing chain, when the amount of oil required and the position that is to be lubricated change according to the operational state of the engine, it is difficult to carry out appropriate lubrication according to the changes.
SUMMARY OF THE INVENTION
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to enable a timing chain wrapped around a sprocket of a camshaft to be reliably lubricated according to the operational state of an engine.
In order to achieve the above-mentioned object, in accordance with a first aspect of the present invention, there is proposed a timing chain lubricating system for an engine in which a sprocket is fixed to an end of a camshaft and a timing chain is wrapped around the sprocket, comprising a plurality of oil supply means for supplying oil to the timing chains the operation of the plurality of oil supply means being changed according to the operational state of the engine.
In accordance with the above-mentioned arrangement since the operation of the plurality of oil supply means for supplying oil to the timing chain is changed according to the operational state of the engine, lubrication can be carried out according to the operational state of the engine thus reducing the wear of the timing chain.
Furthermore, in accordance with a second aspect of the present invention, in addition to the above-mentioned first aspect, there is proposed a timing chain lubricating system for an engine, wherein the number of oil supply means that are in operation is increased as the rotational speed of the engine or the engine load increases.
In accordance with the above-mentioned arrangement, since the number of oil supply means that are in operation is increased as the rotational speed of the engine or the engine load increases, the number of positions that are lubricated can be increased according to the rotational speed of the engine or the engine load thus further effectively reducing the wear of the timing chain,
Furthermore, in accordance with a third aspect or a sixth aspect of the present invention, in addition to the above-mentioned first aspect or second aspect, there is proposed a timing chain lubricating system for an engine, further comprising variable valve lift means for changing the relationship between the size of the valve lift of an intake valve and the size of the valve lift of an exhaust valve according to the operational state of the engine, the amount of oil that is supplied to the section where the sprocket that drives the valve having a large valve left is meshed with the timing chain being made larger than the amount of oil that is supplied to the section where the sprocket that drives the valve having a small valve lift is meshed with the timing chain.
In accordance with the above-mentioned arrangement, since the relationship between the size of the valve lift of the intake valve and the size of the valve lift of the exhaust valve is changed by the variable valve lift means so that the amount of oil that is supplied to the section where the sprocket that drives the valve having a large valve lift is meshed with the timing chain is larger than the amount of oil that is supplied to the section where the sprocket that drives the valve having a small valve lift is meshed with the timing chain, a larger amount of oil can be supplied to the sprocket having a larger valve operating load so prolonging the life span of the timing chain.
Furthermore, in accordance with a fourth aspect, a fifth aspect or a seventh aspect of the present invention, in addition to any one of the above-mentioned first aspect to third aspect, there is proposed a timing chain lubricating system for an engine, further comprising a hydraulic control valve for switching over between a low speed valve lift and a high speed valve lift, the low speed valve lift being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift being used when the rotational speed of the engine or the engine load is higher than a predetermined value, the timing chain being lubricated with relief oil from the hydraulic control valve when the low speed valve lift is established and the timing chain being lubricated with valve lift control oil from the hydraulic control valve when the high speed valve lift is established.
In accordance with the above-mentioned arrangement in which the hydraulic control valve establishes a low speed valve lift when the rotational speed of the engine or the engine load is low and a high speed valve lift when the rotational speed of the engine or the engine load is high, when the low speed valve lift, which imposes a low load on the timing chain, is established the timing chain is lubricated with relief oil from the hydraulic control valve; when the high speed valve lift, which imposes a high load on the timing chain, is established the timing chain is lubricated with valve lift control oil from the hydraulic control valve, aid an amount of oil that is appropriate for the state of the load can thus be supplied to the timing chain so effectively preventing wear of the timing chain.
Furthermore, in accordance with an eighth aspect of the present invention, in addition to the above-mentioned first aspect there is proposed a timing chain lubricating system for an engine, further comprising an oil jet that issues a jet of chain lubricating oil when the rotational speed of the engine or the engine load is higher than a predetermined value.
In accordance with the above-mentioned arrangement, since the oil jet issues a jet of chain lubricating oil when the rotational speed of the engine or the, engine load is higher than the predetermined value, it becomes easy to supply oil to the timing chain.
Furthermore, in accordance with a ninth aspect of the present invention, in addition to the above-mentioned first aspect, there is proposed a timing chain lubricating system for an engine, further comprising an oil jet and a hydraulic control valve for switching over between a low speed valve lift and a high speed valve lift, the low speed valve lift being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift being used when the rotational speed of the engine or the engine load is higher than the predetermined value, the timing chain being lubricated with relief oil from the hydraulic control valve when the low speed valve lift is established and the timing chain being lubricated with valve lift control oil from the; hydraulic control valve via the oil jet when the high speed valve lift is established.
In accordance with the above-mentioned arrangement in which the hydraulic control valve establishes a low speed valve lift when the rotational speed of the engine or the engine load is low and a high speed valve lift when the rotational speed of the engine or the engine load is high, when the low speed valve lift, which imposes a low load on the timing chain, is established the timing chain is lubricated with relief oil from the hydraulic control valve; in the high speed valve lift, which imposes a high load on the timing chain, is established the timing chain is lubricated with valve lift control oil from the hydraulic control valve via the oil jet, an amount of oil that is appropriate for the state of the load can thus be supplied to the timing chain so effectively preventing wear of the timing chain and, moreover, it becomes easy to supply oil to the timing chain.
Furthermore, in accordance with a tenth aspect of the present invention, in addition to the above-mentioned eighth aspect, there is proposed a timing chain lubricating system for an engines wherein the camshaft is supported by an upper camshaft holder and a lower camshaft holder and the oil jet is fastened to the lower camshaft holder.
In accordance with the above-mentioned arrangement, since the camshaft is supported by the upper camshaft holder and the lower camshaft holder and the oil jet is fastened to the lower camshaft holder, the rigidity with which the camshaft and the oil jet are supported can be enhanced,
Furthermore, in accordance with an eleventh aspect of the present invention, in addition to the above-mentioned eighth aspect, there is proposed a timing chain lubricating system for an engine, further comprising a relief oil discharge hole, the relief oil discharge hole and the oil jet being disposed on the side of the sprocket that is close to the hydraulic control valve.
In accordance with the above-mentioned arrangement, since the relief oil discharge hole and the oil jet are disposed on the side of the sprocket that is close to the hydraulic control valve, the oil passage can be shortened,
Furthermore, in accordance with a twelfth aspect of the present inventions in addition to the above-mentioned eleventh aspect, there is proposed a timing chain lubricating system for an engine, wherein the oil jet lubricates the section where the sprocket is meshed with the chain on the side that is far from the hydraulic control valve
In accordance with the above-mentioned arrangement, since the oil jet lubricates the section where the sprocket is meshed with the chain on the side that is far from the hydraulic control valve, it becomes easy to supply oil to the section to be lubricated.
An intake camshaft
12
and an exhaust camshaft
13
of the embodiments correspond to the camshafts of the present invention, an intake camshaft sprocket
15
an exhaust camshaft sprocket
16
of the embodiments correspond to the sprockets of the present invention, an oil drain hole
25
b
and an oil jet
36
of the embodiments correspond to the oil supply means of the present invention, a first hydraulic control valve
34
of the embodiments corresponds to the hydraulic control valve of the present invention, and a fist variable valve operating characteristic mechanism V
1
of the embodiments corresponds to the variable lift means of the present invention.
Furthermore, the above-mentioned predetermined value for the engine rotational speed is, for example, 2500 rpm when the valve lift is switched over on the low speed side and, for example, 5000 rpm when the valve lift is switched over on the high speed side, but it is not limited thereby,
The above-mentioned objects, other objects, characteristics and advantages of the present invention will become apparent from explanation of preferred embodiments that will be described in detail below by reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1
to
13
illustrate a first embodiment of the present invention.
FIG. 1
is a perspective view of an engine.
FIG. 2
is a magnified view from arrow
2
in FIG.
1
.
FIG. 3
is a magnified view from arrow
3
in FIG.
1
.
FIG. 4
is a cross section at line
4
—
4
in FIG.
3
.
FIG. 5
is a magnified view of an essential part of FIG.
4
.
FIG. 6
is a diagram for explaining the action corresponding to FIG.
5
.
FIG. 7
is a view from line
7
—
7
in FIG.
3
.
FIG. 8
is a magnified cross section at line
8
—
8
in FIG.
3
.
FIG. 9
is a magnified cross section of an essential part of FIG.
3
.
FIG. 10
is a magnified cross section at line
10
—
10
in FIG
2
.
FIG. 11
is a cross section at line
11
—
11
in
FIG. 3
,
FIG. 12
is a cross section at line
12
—
12
in FIG.
11
.
FIG. 13
is a diagram for explaining a state in which a measurement apparatus is used.
FIG. 14
is a diagram corresponding to
FIG. 8
relating to a second embodiment of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
A first embodiment of the present invention is explained below by reference to
FIGS. 1
to
13
.
As shown in
FIG. 1
, a DOHC type in-line four cylinder engine E has a crankshaft
11
, an intake camshaft
12
and an exhaust camshaft
13
. A timing chain
17
is wrapped around a crankshaft sprocket
14
provided on a shaft end of the crankshaft
11
, an intake camshaft sprocket
15
provided on a shaft end of the intake camshaft
12
and an exhaust camshaft sprocket
16
provided on a shaft end of the exhaust camshaft
13
. The timing chain
17
is driven in the direction of the arrow a by the crankshaft
11
. The intake camshaft
12
and the exhaust camshaft
13
rotate at a speed that is half that of the crankshaft
11
. Each of the cylinders has two intake valves
18
driven by the intake camshaft
12
and to exhaust valves
19
driven by the exhaust camshaft
13
. The amount of valve lift and the duration for which the valve is open for the two intake valves
18
can be controlled by a first variable valve operating characteristic mechanism V
1
provided on each of the cylinders. The valve timing can be controlled by a second variable valve operating characteristic mechanism V
2
provided on the shaft end of the intake camshaft
12
.
As shown in
FIGS. 2
to
4
, on the upper face of a cylinder block
21
is superimposed a cylinder head
23
via a gasket
22
, and it is fastened by a plurality of bolts
24
. On the upper face of the cylinder head
23
are superimposed a lower camshaft holder
25
, which also functions as a rocker arm shaft holder, and an upper camshaft holder
26
, and they are together fastened to the cylinder head
23
by four bolts
27
,
28
,
29
and
30
. Upper parts of the lower camshaft holder
25
and the upper camshaft holder
26
are covered with a head cover
31
. In the lower camshaft holder
25
are fixed an intake rocker arm shaft
32
and an exhaust rocker arm shaft
33
. The intake camshaft
12
and the exhaust camshaft
13
are rotatably supported in the plane in which the lower camshaft holder
25
and the upper camshaft holder
26
are joined together.
As is clear from referring to
FIGS. 5 and 7
together, an oil passage P
1
connected to an oil pump (not illustrated) driven by the crankshaft
11
is formed in the cylinder head
23
, and an oil passage P
2
branching from the oil passage P
1
communicates with a first hydraulic control valve
34
mounted on the side of the cylinder head
23
. An oil passage P
6
that originates from the first hydraulic control valve
34
and goes through the inside of the cylinder head
23
further extends upward and communicates with an oil passage P
7
formed on the lower face of a protruding expanded part
25
a
(the plane in which the protruding expanded part
25
a
and the cylinder head
23
are joined together), which is integral with the lower camshaft holder
26
. At the downstream end of the oil passage P
7
is formed an oil drain hole
25
b
which is opposite the start of the section where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
. The oil drain hole
25
b
is slightly constricted in comparison with the cross section of the flow passage of the oil passage P
7
so that the oil can reliably be supplied to the above-mentioned start of the meshed section. A blind cap
35
is provided on the upper face of the protruding expanded part
25
a
of the lower camshaft holder
25
at a position that is an extension of the oil passage P
6
that extends upward within the cylinder head
23
.
An oil passage P
9
that originates from the first hydraulic control valve
34
and extends horizontally within the cylinder head
23
communicates with an oil passage P
10
that extends upward. The oil passage P
10
opens on the upper face of the cylinder head
23
and communicates with an oil passage P
11
formed on the lower face of the lower camshaft holder
25
. The oil passage P
11
of the lower camshaft holder
25
communicates with oil passages P
12
and P
13
formed on the outer peripheries of the two bolts
28
and
29
of the four bolts
27
to
30
that fasten both the lower camshaft holder
25
and the upper camshaft holder
26
to the cylinder head
23
. The oil passage P
12
formed on the outer periphery of the bolt
28
communicates with both an oil passage
33
a
formed within the exhaust rocker arm shaft
33
in the axial direction and an oil let
36
provided in the lower camshaft holder
25
. The oil passage P
13
formed on the outer periphery of the bolt
29
communicates with an oil passage
32
a
formed within the intake rocker arm shaft
32
in the axial direction.
As is clear from
FIG. 8
, the oil jet
36
includes an oil jet main body
37
having a nozzle hole
37
a
and a mounting bolt
39
for fixing the oil lot main body
37
to the lower camshaft holder
25
via a sealing member
38
. Within the mounting bolt
39
is housed a relief valve
40
, the upstream side of the relief valve
40
communicating with the oil passage P
12
formed on the outer periphery of the bolt
28
and the downstream side of the relief valve
40
communicating with the nozzle hole
37
a
of the oil jet main body
37
. Fitting a positioning projection
37
b
formed on the oil jet main body
37
in a positioning hole
25
c
formed in the lower camshaft holder
25
positions the nozzle hole
37
a
so that it is directed toward the start of the section where the intake camshaft sprocket
15
is meshed with the timing chain
17
.
The oil jet
38
is placed in a dead space interposed between the lower camshaft holder
25
and the exhaust camshaft sprocket
16
so as to be housed within the outer diameter of the exhaust camshaft sprocket
16
. It is therefore possible to minimize the influence an other members from mounting the oil jet
36
. In particular, since the oil jet
36
is placed by effectively utilizing the dead space behind the exhaust camshaft sprocket
16
, which is not where the second variable valve operating characteristic mechanism V
2
is provided, it is possible to minimize any increase in the dimensions of the engine E and any interference with the mounting of other members from mounting the oil jet
36
. As shown in
FIG. 2
, the oil jet
36
is opposite a cut-out hole
16
a
that is formed in the exhaust camshaft sprocket
16
in order to reduce the weight of the exhaust camshaft sprocket
16
. That is to say, since the oil jet
36
faces the cut-out hole
16
a
formed in the exhaust camshaft sprocket
16
, it is possible to easily check through the cut-out hole
16
a
the presence of the oil jet
36
and the state in which it is mounted.
If the entire mounting bolt
39
of the oil jet
36
is placed within the cut-out hole
16
a
of the exhaust camshaft sprocket
16
, the mounting bolt
39
can be attached/detached through the cut-out hole
16
a
thus enhancing the ease of maintenance. If the entire oil jet
36
is placed within the cut-out hole
16
a
of the exhaust camshaft sprocket
18
, the oil jet
36
can be attached/detached through the cut-out hole
16
a
thus enhancing the ease of maintenance.
As is clear from
FIGS. 3
,
4
and
8
, a chain guide
41
is fastened by the two bolts
28
and
29
(inner bolts placed inside the intake camshaft
12
and the exhaust camshaft
13
) that fasten the upper camshaft holder
26
. The above-mentioned two bolts
28
and
29
that fasten the upper camshaft holder
26
are offset relative to the two bolts
27
and
30
(outer bolts placed outside the intake camshaft
12
and the exhaust camshaft
13
) that are placed outside the two bolts
28
and
29
by a distance
6
in a direction away from the oil jet
36
. This allows a mounting space for the oil jet
36
to be secured while avoiding any interference with the bolts
28
and
29
and, moreover, the rigidity with which the oil jet
36
is supported can be enhanced.
Since one bolt
28
of the two offset bolts
28
and
29
overlaps the oil jet
36
in the axial direction of the exhaust camshaft
13
, not only can the dimensions of the lower camshaft holder
25
be reduced, but also the rigidity with which the exhaust camshaft
13
is supported can be enhanced. This is because placing the oil jet
36
in a position closer to the bolt
29
than to the bolt
28
(on the side away from the exhaust camshaft
13
) would increase the dimensions of the lower camshaft holder
25
by a proportion corresponding to the space required for the oil jet
36
, if, on the other hand, the oil jet
36
were placed closer to the exhaust camshaft
13
side rather than to the bolt
28
, it would be necessary to form a mounting hole for the oil jet
36
close to the face of the lower camshaft holder
25
that supports the exhaust camshaft
13
and there would, therefore, be a possibility that the rigidity with which the exhaust camshaft
13
is supported might be degraded. Furthermore, since the oil passage P
12
extending to the oil jet
36
is formed around the above-mentioned bolt
28
, the oil passages for supplying oil to the oil jet
36
can be arranged simply and at the same time the oil passages can be shortened.
The chain guide
41
has a chain guide main body
42
made of a metal sheet. The lower face of a sliding member
43
made of a synthetic resin provided at the extremity of the chain guide main body
42
is in sliding contact with the upper face of the timing chain
17
. The sliding member
43
can guide the timing chain
17
while restricting its vibration so as to suppress wear of the timing chain
17
, and the sliding resistance between the chain guide
41
and the timing chain
17
can thus be reduced. A pair of tooth skipping prevention plates
42
a
and
42
b
are formed integrally at both ends of the chain guide main body
42
in the longitudinal direction. One tooth skipping prevention plate
42
a
covers the start of the section where the intake camshaft sprocket
15
is meshed with the timing chain
17
and prevents tooth skipping of the timing chain
17
. The other tooth skipping prevention plate
42
b
covers the end of the section where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
and prevents tooth skipping of the timing chain
17
. Since the rigidity of the chain guide
41
increases due to the presence of the two tooth skipping prevention plates
42
a
and
42
b,
the rigidity with which the intake camshaft
12
and the exhaust camshaft
13
are supported is further enhanced.
Since the tooth skipping prevention plates
42
a
and
42
b
are formed at the two ends of the sliding member
43
made of a synthetic resin, even though the sliding member
43
is made of a synthetic resin its durability is enhanced.
The upper camshaft holder
26
includes a cam cap
26
a
for restraining the intake camshaft
12
, a cam cap
26
b
for restraining the exhaust camshaft
13
and a connecting wall
26
c
for providing a connection between the two caps
26
a
and
26
b.
Between the two bolts
28
and
29
and the connecting wall
26
c,
that is to say, on a face of the connecting wall
26
c
opposite the chain guide
41
is formed a U-shaped recess
26
d
for reducing the weight of the upper camshaft holder
26
. In addition to the lower ends of the two cam caps
26
a
and
26
b
being connected to each other through the connecting wall
26
c,
the upper ends thereof are connected to each other by the chain guide
41
. That is to say, since the chain guide
41
is mounted so as to bridge the recess
26
d
formed between the two cam caps
26
a
and
26
b
and the connecting wall
2
c,
the two cam caps
26
a
and
26
b
can be connected by means of both the connecting wall
26
c
and the chain guide
41
while reducing the weight of the upper camshaft holder
26
and maintaining an adequate rigidity and the rigidity with which the intake camshaft
12
and the exhaust camshaft
13
are supported can be enhanced.
As hereinbefore described, since the chain guide
41
is fastened by means of the two bolts
28
and
29
among the four bolts
27
to
30
that also fasten both the lower camshaft holder
25
and the upper camshaft holder
26
to the cylinder head
23
, the number of parts is reduced and the rigidity with which the chain guide
41
is mounted is enhanced. Although the height of the seats for the two inner bolts
28
and
29
fixing the chain guide
41
, among the above-mentioned four bolts
27
to
30
, is restricted by the height of the timing chain
17
, the height of the seats for the two outer bolts
27
and
30
that are not involved in the fixing of the chain guide
41
is not restricted by the height of the timing chain
17
and can be made low. It is thereby possible to lower the two ends of the upper camshaft holder
26
relative to the seat, for the bolts
28
and
29
thus achieving a reduction in the dimensions of the head cover
31
.
Referring again to
FIG. 4
, a filter housing
45
is fixed to a side of the cylinder head
23
by means of bolts
44
. An oil passage P
14
branching from the oil passage P
1
of the cylinder head
23
extends in a direction away from the first variable valve operating characteristic mechanism V
1
and communicates with an oil passage P
16
of the cylinder head
23
via a filter
46
within the filter housing
45
, and an oil passage P
15
. The oil passage P
16
communicates with a second hydraulic control valve
47
housed within the cylinder head
23
(an end wall of the cylinder head
23
on the timing chain
17
side). The second hydraulic control valve
47
communicates with the outer periphery of the intake camshaft
12
via oil passages
17
a
and
17
b
formed in the cylinder head
23
and oil passages
18
a
and
18
b
formed in the lower camshaft holder
26
. The filter housing
45
is mounted utilizing a space on the side of the cylinder head
23
that is opposite the side of the cylinder head
23
on which the first hydraulic control valve
34
is mounted.
Next, the structure of the first hydraulic control valve
34
is explained by reference to FIG.
5
.
The first hydraulic control valve
34
provided on the side of the cylinder head
23
has a valve hole
51
a
formed within a valve housing
51
. The two ends of an oil passage P
3
passing through a lower part of the valve hole
51
a
communicate with the oil passage P
2
and an oil passage P
4
respectively. The two ends of an oil passage P
5
passing through a middle part of the valve hole
51
a
communicate with the oil passage P
9
and the oil passage P
4
respectively. An upper part of the valve hole
51
a
communicates with the oil passage P
6
via a drain port
51
b.
A filter
52
is attached to the entrance of the oil passage P
3
. On a spool
53
housed within the valve hole
51
a
are formed a pair of lands
53
a
and
53
b,
a groove
53
c
interposed between the two lands
53
a
and
53
b,
an inner hole
53
d
extending in the axial directions an orifice
53
e
passing through the upper end of the inner hole
53
d,
and a groove
53
f
providing communication between the inner hole
53
d
and the drain port
51
b.
The spool
53
is forced upward by a spring
54
housed in the lower end of the inner hole
53
d
and is in contact with a cap
55
blocking the upper end of the valve hole
51
a.
The oil passage P
4
and the oil passage P
5
communicate with each other via an orifice
51
c.
An ON/OFF solenoid
56
is provided between the oil passage P
4
and an oil passage P
8
so as to allow or block communication therebetween.
Next, the structure of the first variable valve operating characteristic mechanism V
1
is explained by reference to FIG.
9
.
The first variable valve operating characteristic mechanism V
1
for driving the intake valves
18
includes first and second low speed rocker arms
57
and
58
pivotally supported on the intake rocker arm shaft
32
in a rockable manner and a high speed rocker arm
59
interposed between the two low speed rocker arms
57
and
58
. Sleeves
60
,
61
and
62
are press-fitted into the middle sections of the corresponding rocker arms
57
,
58
and.
59
. A roller
63
that is rotatably supported around the sleeve
60
is in contact with a low speed intake cam
64
provided on the intake camshaft
12
. A roller
65
that is rotatably supported around the sleeve
61
is in contact with a high speed intake cam
66
provided on the intake camshaft
12
. A roller
67
that is rotatably supported around the sleeve
62
is in contact with a low speed intake cam
68
provided on the intake camshaft
12
. The cam lobe of the high speed intake cam
66
is made higher than the cam lobes of the pair of low speed intake cams
64
and
68
, which have an identical profile.
A first switch-over pin
69
, a second switch-over pin
70
and a third switch-over pin
71
are slidably supported within the three sleeves
60
,
61
and
62
. The first switch-over pin
69
is forced toward the second switch-over pin
70
by a spring
73
disposed in a compressed manner between the first switch-over pin
69
and the spring seat
72
fixed to the sleeve
60
and stops in a position in which the first switch-over pin
69
is in contact with a clip
74
fixed to the sleeve
60
. At this point, the plane in which the first switch-over pin
69
and the second switch-over pin
70
are in contact with each other is positioned between the first low speed rocker arm
57
and the high speed rocker arm
59
, and the plane in which the second switch-over pin
70
and the third switch-over pin
71
are in contact with each other is positioned between the high speed rocker arm
59
and the second low speed rocker arm
58
. An oil chamber
58
a
formed within the second low speed rocker arm
58
communicates with the oil passage
32
a
formed within the intake rocker arm shaft
32
.
When no hydraulic pressure acts on the oil passage
32
a
of the intake rocker arm shaft
32
, the first to third switch-over pins
69
to
71
are in the positions shown in FIG.
9
. The first and second low speed rocker arms
57
and
58
and the high speed rocker arm
59
can rock freely. The pair of intake valves
18
are therefore driven with a low valve lift by the first low speed rocker arm
57
and the second low speed rocker arm
58
respectively. At this point, the high speed rocker arm
59
is detached from the first low speed rocker arm
57
and the second low speed rocker arm
58
and rotates without effect on the action of the pair of intake valves
18
.
When a hydraulic pressure acts on the oil chamber
58
a
through the oil passage
32
a
of the intake rocker arm shaft
32
, the first to third switch-over pins
69
to
71
move against the spring
73
, and the first and second low speed rocker arms
57
and
58
and the high speed rocker arm
59
are united. As a result, the first and second low speed rocker arms
57
and
58
and the high speed rocker arm
59
are driven as a unit by the high speed intake cam
66
having the high cam lobe, and the pair of intake valves
18
connected to the first low speed rocker arm
57
and the second low speed rocker arm
58
are driven with a high valve lift. At this point, the pair of low speed intake cams
64
and
68
are detached from the first and second low speed rocker arms
57
and
58
and rotate without effect.
Next, the structure of the second hydraulic control valve
47
is explained by reference to FIG.
10
.
Five ports
82
to
86
are formed in a cylindrical valve housing
81
fitted in a valve hole
23
a
formed in the cylinder head
23
. The central port
84
communicates with the oil passage P
16
, the ports
83
and
85
that are on either side of the central port
84
communicate with the pair of oil passages P
17
a
and P
17
b
respectively, and the ports
82
and
86
that are outside the ports
83
and
85
communicate with a pair of oil drainage passages P
19
a
and P
19
b
respectively. Three grooves
87
,
88
and
89
are formed on the outer periphery of a spool
90
. The spool
90
is slidably fitted in the valve housing
81
, and forced by the resilient force of a spring
91
toward a linear solenoid
92
, the spring being disposed on one end of the spool
90
and the solenoid
92
being disposed on the other end thereof.
When the spool
90
is in a neutral position as shown in the figures all of the oil passages P
16
, P
17
a
and P
17
b
are blocked. When the spool
90
is moved leftward from the neutral position by duty control of the linear solenoid
92
, the oil passage P
16
communicates with the oil passage P
17
a
via the port
84
, the groove
88
and the port
83
and the oil passage P
17
b
communicates with the oil passage
19
b
via the port
85
, the groove
89
and the port
86
. When the spool
90
is moved rightward from the neutral position by duty control of the linear solenoid
92
, the oil passage P
16
communicates with the oil passage P
17
b
via the port
84
, the groove
88
and the port
85
, and the oil passage P
17
a
communicates with the oil passage
19
a
via the port
83
, the groove
87
and the port
82
.
Next, the structure of the second variable valve operating characteristic mechanism V
2
is explained by reference to
FIGS. 11 and 12
.
The second variable valve operating characteristic mechanism V
2
includes an outer rotor
93
and an inner rotor
96
fixed to the intake camshaft
12
by means of a pin
94
and bolts
95
. The outer rotor
93
includes a cap-shaped housing
97
, the intake camshaft sprocket
15
being formed integrally on the outer periphery of the housing
97
, an outer rotor main body
98
fitted in the housing
97
and an annular cover plate
99
covering the opening of the housing
97
, and these are combined integrally by means of four bolts
100
. A support hole
97
a
is formed in the center of the housing
97
, and fitting the support hole
97
a
around the outer periphery of the intake camshaft
12
allows the outer rotor
93
to be supported on the intake camshaft
12
in a relatively rotatable manner.
On the inner periphery of the outer rotor main body
98
are alternately formed four recesses
98
a
and four projections
98
b.
Four vanes
96
a
formed radially on the outer periphery of the inner rotor
96
are fitted in the above-mentioned four recesses
98
respectively. Sealing members
101
provided on the extremities of the projections
98
b
of the outer rotor main body
98
are in contact with the inner rotor
96
and sealing members
102
provided on the extremities of the vanes
96
a
of the inner rotor
96
are in contact with the outer rotor main body
98
thus defining four advance chambers
103
and four retard chambers
104
between the outer rotor main body
98
and the inner rotor
96
.
A stopper pin
105
is slidably supported in a pin hole
96
b
formed in the inner rotor
96
. An arc-shaped long channel
97
b
with which the extremity of the stopper pin
105
can engage is formed in the housing
97
of the outer rotor
93
. The stopper pin
105
is forced by a spring
106
in the direction in which the stopper pin
105
becomes detached from the long channel
97
b.
An oil chamber
107
is formed at the back of the stopper pin
105
. When the stopper pin
105
becomes detached from the long channel
97
b
due to the resilient force of the spring
106
, the outer rotor
93
and the inner rotor
96
can rotate relative to each other within an angle α (e.g. 30°) in which each of the vanes
96
a
of the inner rotor
96
can move from one end of the corresponding recess
98
a
of the outer rotor
93
to the other end thereof. When a hydraulic pressure is supplied to the oil chamber
107
so making the stopper pin
105
engage with the long channel
97
b,
the outer rotor
93
and the inner rotor
96
can rotate relative to each other within an angle β (e.g. 20°) in which the stopper
105
can move from one end of the long channel
97
b
to the other end thereof.
A pair of oil passages P
18
a
and P
18
b
formed in the lower camshaft holder
26
communicate with the advance chambers
103
and the retard chambers
104
respectively via a pair of oil passages
12
a
and
12
b
formed within the intake camshaft
12
and oil passages
96
c
and
96
d
formed in the inner rotor
96
. When a hydraulic pressure is supplied to the advance chambers
103
via the second hydraulic control valve
47
, the low speed intake cams
64
and
68
and the high speed intake cam
66
advance in angle relative to the intake camshaft
12
so advancing the valve timing of the intake valves
18
. On the other hand, when a hydraulic pressure is supplied to the retard chambers
104
via the second hydraulic control valve
47
, the low speed intake cams
64
and
68
and the high speed intake cam
66
are retarded in angle relative to the intake camshaft
12
so retarding the valve timing of the intake valves
18
.
In the second lower camshaft holder
25
viewed from the second variable operating characteristic mechanism V
2
side, is formed an oil passage P
20
that communicates with the oil passage P
13
(FIG.
4
). The oil passage P
20
further communicates with the oil chamber
107
, the top part of the stopper pin
105
facing the oil chamber
107
, via an oil passage
12
c
formed within the intake camshaft
12
and oil passages
95
a
and
95
b
formed within the bolt
95
.
In the present embodiment, no variable valve operating characteristic mechanism is provided on the exhaust camshaft
13
side, and the exhaust valves
19
are driven with an intermediate valve lift. That is to say, the valve lift of the exhaust valves
19
is midway between the valve lift (small lift) of the intake valves
18
at low speed and the valve lift (large lift) at high speed.
The action of the embodiment having the above-mentioned arrangement is now explained.
When the engine E rotates at a low speed, the solenoid
56
of the first hydraulic control valve
34
is in an OFF state, communication between the oil passage P
4
and the oil passage P
8
is blocked, and the spool
53
is in the raised position shown in
FIG. 5
due to the resilient force of the spring
54
. In this state the oil pump communicates with the oil chamber
58
a
of the first variable valve operating characteristic mechanism V
1
via the oil passages P
1
and P
2
of the cylinder head
23
, the oil passages P
3
and P
4
, the orifice
53
c
and the oil passage P
5
of the valve housing
51
, the oil passages P
9
and P
10
of the cylinder head
23
, the oil passages P
11
and P
13
of the lower camshaft holder
25
and the oil passage
32
a
within the intake rocker arm shaft
32
. At this point, since the hydraulic pressure that is transmitted to the oil chamber
58
a
of the first variable valve operating characteristic mechanism V
1
is low due to the action of the orifice
53
c,
the first to third switch-over pins
69
,
70
and
71
are retained in the positions shown in
FIG. 9
, the pair of intake valves
18
are driven with a low valve lift and the valve operation system (rocker arm support parts, camshaft support parts, etc.) can be lubricated with this low pressure oil.
As described above, when the hydraulic pressure output by the first hydraulic control valve
34
is low, the hydraulic pressure that is transmitted to the oil chamber
107
of the second variable valve operating characteristic mechanism V
2
via the oil passage P
20
of the lower camshaft holder
25
and the oil passage
12
c
within the intake camshaft
12
shown in
FIG. 11
is low, and the stopper pin
105
becomes detached from the long channel
97
b
due to the resilient force of the spring
106
. Controlling the duty ratio of the second hydraulic control valve
47
(FIG.
10
), which is connected to the oil pump via the oil passages P
1
and P
14
of the cylinder head
23
, the oil passage P
15
within the filter housing
45
and the oil passage P
16
of the cylinder head
23
, generates a difference between the hydraulic pressures transmitted via the pair of oil passages
17
a
and
17
b
to the advance chambers
103
and the retard chambers
104
of the second variable valve operating characteristic mechanism V
2
. As a result, the phase of the inner rotor
96
relative to the outer rotor
93
can be varied in the range of the angle α (
FIG. 12
) so controlling the valve timing of the intake valves
18
.
When the engine E rotates at a low speed as described above, the oil (relief oil) that has passed through the orifice
53
c
of the first hydraulic control valve
34
and has a reduced pressure flows through the oil passage P
5
, the groove
53
c
of the spool
53
, the drain port
51
b,
the oil passage P
6
of the cylinder head
23
and the oil passage P
7
of the protruding expanded part
25
a
of the lower camshaft holder
25
and flows out of the oil drain hole
25
b
to the start of the section (or meshed section) where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
so lubricating the timing chain
17
(FIG.
7
). Since the rotational speed of the timing chain
17
is low when the engine E rotates at a low speeds only a small amount of the oil that has become attached to the timing chain
17
scatters due to centrifugal force. If oil is supplied to the start of the section where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
, which is to the rear in the rotational direction of the timing chain
17
, since the engine E is rotating at a low speed with a small load imposed on the timing chain
17
, the section where the intake camshaft sprocket
15
is meshed with the timing chain
17
, which is to the front in the rotational direction of the timing chain
17
, can be lubricated well.
As hereinbefore described, since the timing chain
17
is lubricated with the relief oil of the first hydraulic control vale
34
flowing out through the oil drain hole
25
b,
it is unnecessary to employ an oil jet and secure a space for mounting it. Moreover, since the oil passage P
7
connected to the oil drain hole
25
b
is formed in the plane in which the cylinder head
23
and the lower camshaft holder
25
are joined together, the oil passage P
7
can be arranged simply. Furthermore, since the first hydraulic control valve
34
is mounted on the side wall of the cylinder head
23
that is close to the oil drain hole
26
b,
the length of the oil passage P
7
for the above-mentioned relief oil can be reduced and the rigidity with which the first hydraulic control valve
34
is mounted can be enhanced in comparison with a case where the first hydraulic control valve
34
is mounted on a side wall of the cylinder head that is far from the oil drain hole
25
b.
Furthermore, since the oil passage P
7
for the relief oil, which is formed in the plane in which the cylinder head
23
and the lower camshaft holder
25
are joined together, and the first hydraulic control valve
34
are placed in a same plane that is perpendicular to the camshafts
12
and
13
, the lengths of the oil passages P
6
and P
7
from the first hydraulic control valve
37
to the oil drain hole
25
b
can be further reduced.
As shown in
FIG. 6
, when the engine E rotates at a high speed and the solenoid
56
of the first hydraulic control valve
34
is in an ON state so providing communication between the oil passage P
4
and the oil passage P
8
and moving the spool
53
downward due to the hydraulic pressure acting on the land
53
b,
the oil passage P
3
and the oil passage P
5
communicate with each other via the groove
53
c.
As a result, a high hydraulic pressure is transmitted to the oil chamber
58
a
of the first variable valve operating characteristic mechanism V
1
via the oil passages P
9
and P
10
of the cylinder head
23
, the oil passages P
11
and P
13
of the lower camshaft holder
25
and the oil passage
32
a
within the intake rocker arm shaft
32
, the first to third switch-over pins
69
,
70
and
71
move against the spring
73
and the pair of intake valves
18
are driven with a high valve lift.
As hereinbefore described, when the hydraulic pressure output by the first hydraulic control valve
34
is high, the hydraulic pressure that is transmitted to the oil chamber
107
of the second variable valve operating characteristic mechanism V
2
via the oil passage P
20
of the lower camshaft holder
25
and the oil passage
12
c
within the intake camshaft
12
shown in
FIG. 11
also becomes high so engaging the stopper pin
105
with the long channel
97
b
against the spring
106
. It is therefore possible by controlling the duty ratio of the second hydraulic control valve
47
, which is connected to the oil pump via the oil passages P
1
and P
14
of the cylinder head
23
, the oil passage P
15
within the filter housing
45
and the oil passage P
16
of the cylinder head
23
, to generate a difference between the hydraulic pressures transmitted via the pair of oil passages P
17
a
and P
17
b
to the advance chambers
103
and the retard chambers
104
of the second variable valve operating characteristic mechanism V
2
thus varying the phase of the inner rotor
96
relative to the outer rotor
93
in the range of the angle β (FIG.
12
), so as to control the valve timing of the intake valves
18
.
In
FIG. 8
, when the engine E rotates at high speed, oil at a high pressure supplied to the oil passage P
12
formed on the outer periphery of the bolt
28
pushes the relief valve
40
within the mounting bolt
39
of the oil jet
36
so as to open it and issues from the nozzle hole
37
a
of the oil jet main body
37
thus lubricating the start of the section (or meshed section) where the intake camshaft sprocket
15
is meshed with the timing chain
17
. In FIG,
6
, the oil supplied to the oil passage P
8
of the first hydraulic control valve
34
flows through the orifice
53
e,
the inner hole
53
d
and the groove
53
f
of the spool
53
, the drain port
51
b
of the valve housing
51
, the oil passage P
6
of the cylinder head
23
and the oil passage P
7
of the protruding expanded part
25
a
of the lower camshaft holder
25
and flows out from the oil drain hole
26
b
toward the start of the section (or meshed section) where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
thus lubricating the timing chain
17
(FIG.
7
).
As described above, when the engine E rotates at a low speed with a low load on the timing chain
17
, only the start of the section where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
Is lubricated with the relief oil. When the engine E rotates at a high speed with a high load on the timing chain
17
, the start of the section where the intake camshaft sprocket
16
is meshed with the timing chain
17
is lubricated intensively with oil from the oil jet
36
and at the same time the start of the section where the exhaust camshaft sprocket
16
is meshed with the timing chain
17
receives auxiliary lubrication with the relief oil from the oil drain hole
25
b,
The timing chain
17
can thus be lubricated optimally according to the operational state of the engine E so enhancing the durability.
That is to say, since the operation of the oil drain hole
25
b
and the oil jet
36
, which form a plurality of oil supply means for supplying oil to the timing chain
17
, are controlled according to the operational state of the engine E, lubrication can be carried out according to the operational state of the engine E so suppressing the wear of the timing chain
17
. Moreover, since the number of oil supply means that are operated is increased as the rotational speed of the engine E increases, the number of parts that are lubricated is increased as the load increases and wear of the timing chain
17
can be suppressed yet more effectively.
In particular, when the engine E rotates at a low speed and the valve lift of the exhaust valves
19
(intermediate valve lift) is larger than the valve lift of the intake valves
18
(small valve lift), a comparatively large amount of oil is supplied to the exhaust camshaft sprocket
16
, the load on the exhaust camshaft sprocket
16
being larger than that on the intake camshaft sprocket
15
. On the other hand, when the engine E rotates at a high speed and the valve lift of the intake valves
18
(large valve lift) is larger than the valve lift of the exhaust valves
19
(intermediate valve lift), a comparatively large amount of oil is supplied to the intake camshaft sprocket
15
, the load on the intake camshaft sprocket
15
being larger than that on the exhaust camshaft sprocket
16
, a comparatively small amount of oil is supplied to the exhaust camshaft sprocket
16
, and supply of an optimal amount of oil can thus be guaranteed according to the operational state of the engine E.
That is to say, the first variable valve operating characteristic mechanism V
1
is provided for varying the relative amount of valve lift between the intake valves
18
and the exhaust valves
19
according to the operational state of the engine E, the amount of oil supplied to the section where the timing chain
17
is meshed with the sprocket that drives the valves having a larger lift being larger than the amount of oil supplied to the section where the timing chain
17
is meshed with the sprocket that drives the valves having a smaller lift, and a larger amount of oil can thus be supplied to the sprocket having a larger valve operating load so prolonging the life span of the timing chain
17
. Moreover, the first hydraulic control valve
34
is provided for switching over between a low speed valve lift and a high speed valve lift, the low speed valve lift being used when the rotational speed of the engine E is lower than a predetermined value and the high speed valve lift being used when the rotational speed of the engine E is higher than the predetermined value. The first hydraulic control valve
34
establishes the low speed valve lift when the engine E rotates at a low speed and the high speed valve lift when the engine E rotates at a high speed; when the low speed valve lift is established, the timing chain
17
is lubricated with low pressure relief oil from the first hydraulic control valve
34
, and when the high speed valve lift is established, the timing chain
17
is lubricated with high pressure valve lift control oil from the first hydraulic control valve
34
, and an amount of oil that is appropriate for the state of the load can thus be supplied to the timing chain
17
so effectively preventing wear thereof.
The operating conditions of the first variable valve operating characteristic mechanism V
1
can easily be checked by detaching the blind cap
35
provided on the protruding expanded part
25
a
of the lower camshaft holder
25
facing the downstream end of the oil passage P
6
of the cylinder head
23
, attaching a measurement apparatus
108
instead of the above-mentioned blind cap
36
as shown in FIG
13
and supplying a fluid pressure of, for example, air from the measurement apparatus
108
. As is dear from
FIG. 5
, since the seat for the blind cap
35
formed in the lower camshaft holder
25
is provided at a lower position than the place where it is joined to the upper camshaft holder, not only can the length of the blind cap
35
be shortened, but also the dimensions of the lower camshaft holder
25
can be reduced.
Merely fitting the extremity of the measurement apparatus
108
in the oil passage P
6
within the cylinder head
23
via a seating member allows the operating conditions of the first variable valve operating characteristic mechanism V
1
to be checked without receiving any influence (escape of fluid pressure) from the oil passage P
7
for the relief oil.
Next, a second embodiment of the present invention is explained by reference to FIG.
14
.
A chain guide
41
of the second embodiment does not have a sliding member
43
made of a synthetic resin; instead, the upstream side of an oil passage
41
a
formed within the chain guide
41
communicates with an oil passage P
12
formed on the outer periphery of a bolt
28
and the downstream side of the oil passage
41
a
communicates with an orifice
41
c
opening on a sliding face
41
b
facing a timing chain
17
. When an engine E rotates at a high speed, and oil at a high pressure is supplied to the oil passage P
12
, the oil issues toward the inner periphery of the timing chain
17
from an oil jet
36
as well as toward the outer periphery of the timing chain
17
, via the orifice
41
c,
from the oil passage
41
a
formed within the chain guide
41
. A sliding section between the sliding face
41
b
of the chain guide
41
and the timing chain
17
can be lubricated effectively with the oil issuing through the orifice
41
c.
It is also possible to make the above-mentioned orifice
41
c
open on tooth skipping prevention plates
42
a
and
42
b
(
FIG. 3
) of the chain guide
41
, and this arrangement allows the sections where the intake camshaft sprocket
15
and the exhaust camshaft sprocket
16
are meshed with the timing chain
17
to be lubricated effectively.
Although embodiments of the present invention have been explained in detail above, the present invention can be modified in a variety of ways without departing from the spirit and scope of the present invention.
Claims
- 1. A timing chain lubricating system for an engine in which a sprocket is fixed to an end of a camshaft and a timing chain is wrapped around the sprocket, the timing chain lubricating system comprising:a plurality of independently operated oil supply means operative to supply oil to the timing chain, and means for changing the operation of the respective independently operated oil supply means according to the operational state of the engine.
- 2. The timing chain lubricating system for an engine according to claim 1, including means for increasing the number of the independently operated oil supply means that are operated as the rotational speed or the engine load increases.
- 3. The timing chain lubricating system for an engine according to claim 1, further comprising:variable valve lift means for changing the relationship between a size of valve lift of an intake valve and a size of valve lift of an exhaust valve according to the operational state of the engine, wherein the means for changing the operation of the respective independently operated oil supply means includes a means controlling the amount of oil that is supplied to the timing chain where the sprocket that drives the valve having a large valve lift meshes with the timing chain being made larger than the amount of oil that is supplied to the timing chain where the sprocket that drives the valve having a small valve lift meshes with the timing chain.
- 4. The timing chain lubricating system for an engine according to claim 1, further comprising:a hydraulic control valve for switching operations of the oil supply means between a low speed valve lift mode and a high speed valve lift mode, the low speed valve lift mode being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift mode being used when the rotational speed of the engine or the engine load is higher than a predetermined value, said hydraulic control valve being operative to lubricate the timing chain with relief oil when the low speed valve lift mode is established and operative to lubricate the timing chain with valve lift control oil when the high speed valve lift mode is established.
- 5. The timing chain lubricating system for an engine according to claim 3, further comprising:a hydraulic control valve for switching operation of the oil supply means between a low speed valve lift mode and a high speed valve lift mode, the low speed valve lift mode being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift mode being used when the rotational speed of the engine or the engine load is higher than a predetermined value, said hydraulic control valve being operative to lubricate the timing chain with relief oil when the low speed valve lift mode is established and operative to lubricate the timing chain with valve lift control oil when the high speed valve lift mode is established.
- 6. The timing chain lubricating system for an engine according to claim 2, further comprising:variable valve lift means for changing the relationship between the size of the valve lift of an intake valve and the size of the valve lift of an exhaust valve according to the operational state of the engine, the amount of oil that is supplied to the timing chain where the sprocket that drives the valve having a large valve lift meshes with the timing chain being made larger than the amount of oil that is supplied to the timing chain where the sprocket that drives the valve having a small valve lift meshes with the timing chain.
- 7. The timing chain lubricating system for an engine according to claim 2, further comprising:a hydraulic control valve for switching peration of the oil supply means between a low speed valve lift mode and a high speed valve lift mode, the low speed valve lift mode being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift mode being used when the rotational speed of the engine or the engine load is higher than a predetermined value, said hydraulic control valve being operative to lubricate the timing chain with relief oil when the low speed valve lift mode is established and operative to lubricate the timing chain with valve lift control oil when the high speed valve lift mode is established.
- 8. The timing chain lubricating system for an engine according to claim 1, further comprising:an oil jet that issues a jet of chain lubricating oil from one of said independently operated oil supply means when the rotational speed of the engine or the engine load is higher than a predetermined value.
- 9. The timing chain lubricating system for an engine according to claim 1, further comprising:an oil jet; and a hydraulic control valve for switching operation of the oil supply means between a low speed valve lift mode and a high speed valve lift mode, the low speed valve lift mode being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed lift mode being used when the rotational speed of the engine or the engine load is higher than the predetermined value, said hydraulic control valve being operative to lubricate the timing chain with relief oil when the low speed valve lift mode is established and operative to lubricate the timing chain with valve lift control via the oil jet when the high speed valve lift mode is established.
- 10. The timing chain lubricating system for an engine according to claim 8, wherein the camshaft is supported by an upper camshaft holder and a lower camshaft holder, and the oil jet is fastened to the lower camshaft holder.
- 11. The timing chain lubricating system for an engine according to claim 8, further comprising a relief oil discharge hole, the relief oil discharge hole and the oil jet being disposed on the side of the sprocket that is close to a hydraulic control valve.
- 12. A timing chain lubricating system for an engine according to claim 11, wherein the oil jet lubricates the timing chain where the sprocket meshes with the timing chain on the side that is far from the hydraulic control valve.
- 13. A timing chain lubricating system for an engine in which a sprocket is fixed to an end of a camshaft and a timing chain is wrapped around the sprocket, the timing chain lubricating system comprising:a plurality of independently operated oil supply means for supplying oil to the timing chain, the operation of each of the plurality of independently operated oil supply means being changed according to the operational state of the engine, and the timing chain lubricating system further comprising: an oil jet; and a hydraulic control valve for switching over between a low speed valve lift and a high speed valve lift, the low speed valve lift being used when the rotational speed of the engine or the engine load is lower than a predetermined value, the high speed valve lift being used when the rotational speed of the engine or the engine load is higher than the predetermined value, the timing chain being lubricated with relief oil from the hydraulic control valve when the low speed valve lift is established and the timing chain being lubricated with valve lift control oil from the hydraulic control valve via the oil jet with the high speed valve lift is established.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-281526 |
Sep 2000 |
JP |
|
US Referenced Citations (8)
Foreign Referenced Citations (1)
Number |
Date |
Country |
6-146838 |
May 1994 |
JP |