U.S. patent application number 15/115538 was filed with the patent office on 2017-06-08 for hydraulic circuit for internal combustion engine.
The applicant listed for this patent is Mikuni Corporatioon. Invention is credited to Hideaki Kusanagi.
Application Number | 20170159508 15/115538 |
Document ID | / |
Family ID | 53757023 |
Filed Date | 2017-06-08 |
United States Patent
Application |
20170159508 |
Kind Code |
A1 |
Kusanagi; Hideaki |
June 8, 2017 |
HYDRAULIC CIRCUIT FOR INTERNAL COMBUSTION ENGINE
Abstract
In a hydraulic circuit including a second oil pump (21) as a
dedicated pump for supplying oil pressure to a VVT (23, 24), the
exhaust side VVT (24) has a rotor and a return spring for holding
the rotor in a most advance angle state in stoppage of an engine.
By obtaining driving force of the second oil pump (21) from an
exhaust side camshaft (26) to which the rotor is connected, it is
possible to reduce an increase in a torque required for operating
the exhaust side VVT (24) through energizing force of the return
spring.
Inventors: |
Kusanagi; Hideaki;
(Takizawa-shi, Iwate, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mikuni Corporatioon |
Takizawa-shi, Iwate |
|
JP |
|
|
Family ID: |
53757023 |
Appl. No.: |
15/115538 |
Filed: |
January 28, 2015 |
PCT Filed: |
January 28, 2015 |
PCT NO: |
PCT/JP2015/052272 |
371 Date: |
July 29, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02T 10/18 20130101;
F01L 2001/34483 20130101; F02D 13/0219 20130101; F01L 1/3442
20130101; Y02T 10/12 20130101; F01L 1/047 20130101; F01L 2001/34423
20130101 |
International
Class: |
F01L 1/344 20060101
F01L001/344; F01L 1/047 20060101 F01L001/047 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2014 |
JP |
2014-016506 |
Claims
1. A hydraulic circuit for an internal combustion engine including
a variable valve timing mechanism for varying a rotation phase of
at least one of an intake side camshaft and an exhaust side
camshaft with respect to a crankshaft of the internal combustion
engine, thereby changing a valve timing of at least one of an
intake valve and an exhaust valve which are to be opened/closed by
the intake side camshaft and the exhaust side camshaft, the
hydraulic circuit comprising: a first oil pump for supplying oil
from an oil pan to a main gallery; and a second oil pump for
supplying the oil to the variable valve timing mechanism, the
variable valve timing mechanism including; a rotor for being
rotated in connection with at least one of the intake side camshaft
and the exhaust side camshaft; and a return spring for energizing
to hold the rotor in a maximum phase angle state in stoppage of the
internal combustion engine, driving force of the second oil pump
being obtained from the camshaft to which the rotor is
connected.
2. The hydraulic circuit for the internal combustion engine
according to claim 1, wherein the rotor is connected to the exhaust
side camshaft and the driving force of the second oil pump is
obtained from the exhaust side camshaft.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hydraulic circuit for an
internal combustion engine, and more particularly, is suitably used
in a hydraulic circuit for an internal combustion engine including
a variable valve timing mechanism for optimally controlling an
open/close timing of an intake/exhaust valve depending on an
operating state.
BACKGROUND ART
[0002] In general, an internal combustion engine (for example, a
four-stroke engine to be used for a motorcycle, an outboard motor
or a snowmobile) is provided with an oil pump for supplying oil
from an oil pan disposed in an engine bottom portion to each
mechanism unit in an upper part thereof. Specifically, oil pressure
fed from the oil pump is supplied to a camshaft or a crankshaft
through a cylinder head. Consequently, each mechanism unit such as
the camshaft or the crankshaft is lubricated and cooled by the
oil.
[0003] FIG. 5 is a diagram showing a passage for oil in the engine.
As shown in FIG. 5, the oil stored in an oil pan 11 is sucked by an
oil pump 12 and is pressure fed to a main gallery 14 through an oil
filter 13. Then, the oil is supplied from the main gallery 14 to
various mechanism units 15, and finally drops by its own weight and
returns to the oil pan 11.
[0004] In some cases, the engine is provided with a control
mechanism referred to as a variable valve timing mechanism (VVT).
The VVT is used for optimally controlling an open/close timing of
an intake/exhaust valve of a cam depending on an operating state,
thereby achieving compatibility of an enhancement in torques in low
and medium speed regions and an enhancement in an output in a high
speed region, a reduction in Nox, an enhancement in fuel
consumption and the like. Control of oil pressure for controlling
the open/close timing of the intake/exhaust valve is performed by
an oil control valve (OCV).
[0005] FIG. 6 is a diagram showing a passage for oil of an engine
including the VVT. As shown in FIG. 6, the oil is supplied from the
main gallery 14 to a VVT (OCV) 16 in addition to various mechanism
units 15 and the open/close timing of the intake/exhaust valve is
controlled by oil pressure of the oil.
[0006] In order to operate the VVT 16 with a high responsiveness
while ensuring the oil pressure for each mechanism unit 15, it is
necessary to increase oil pressure of the main gallery 14 as
compared with the case in which the VVT 16 is not provided. For
this purpose, it is necessary to increase oil pressure of the oil
pump 12 which is pressure at a source. However, there is
consequently caused a problem in that a capacity of the oil pump 12
is increased and a pump space is thus enlarged, resulting in an
increase in a size of the engine.
[0007] On the other hand, there is known that a dedicated pump for
the VVT 16 is provided in addition to the oil pump 12 to enable a
reduction in necessary oil pressure as a whole and a decrease in
the size of the engine (for example, see Patent Document 1). The
hydraulic circuit for the engine described in the Patent Document 1
includes the first hydraulic pump and the second hydraulic pump
which are to be driven synchronously with the crankshaft. The first
hydraulic pump supplies, to the main gallery of the engine, oil
regulated into predetermined pressure by the first relief valve. On
the other hand, the second hydraulic pump sucks the oil from the
main gallery and supplies the oil to the valve control device. In
other words, the second hydraulic pump corresponds to a VVT
dedicated pump.
[0008] In the case in which a dedicated pump for supplying the oil
pressure from the main gallery 14 to the VVT 16 is provided, piping
can be shortened if the dedicated pump is provided in the vicinity
of the cylinder head to be another oil pressure supply destination
from the same main gallery 14. Therefore, this is preferable
because a pressure drop can be suppressed. In that case, it is
supposed that power for driving the dedicated pump is obtained from
the camshaft stored in the cylinder head. In other words, the
camshaft is rotated by power transmitted from the crankshaft by a
timing chain. The power of the dedicated pump is obtained by
utilization of the rotation. There is conventionally known
acquirement itself of power of the oil pump from the camshaft which
is not the dedicated pump for the VVT (for example, see Patent
Document 2).
[0009] Patent Document 1: Japanese Patent No. 3507649
[0010] Patent Document 2: Japanese Patent No. 3368785
DISCLOSURE OF THE INVENTION
[0011] In the case in which the power for the dedicated pump of the
VVT is obtained from the camshaft, however, the driving force of
the camshaft is increased corresponding to at least the power so
that a necessary torque for operating the VVT is increased
correspondingly. For this reason, a load of the VVT required for
changing a rotation phase of the camshaft is increased. As a
result, it is necessary to increase the driving force of the VVT
itself in order to operate the VVT with a high responsiveness,
which is not preferable because an increase in the size of the VVT
and a rise in the oil pressure are required.
[0012] The present invention has been made to solve the problem and
has an object to reduce a load of a VVT and enable the VVT to be
operated with a high responsiveness without requiring an increase
in a size and a rise in oil pressure in a hydraulic circuit for an
internal combustion engine provided with a dedicated pump for
supplying the oil pressure to the WT.
[0013] In order to attain the object, the present invention
provides a hydraulic circuit for an internal combustion engine
including a second oil pump as a dedicated pump for supplying oil
to a VVT in addition to a first oil pump for supplying the oil from
an oil pan to a main gallery, wherein a variable valve timing
mechanism has a rotor for being rotated in connection with at least
one of an intake side camshaft and an exhaust side camshaft and a
return spring for energizing to hold the rotor in a maximum phase
angle state in stoppage of the internal combustion engine, and
driving force of the second oil pump is obtained from the camshaft
to which the rotor is connected.
[0014] According to the present invention having the structure
described above, it is possible to reduce an increase in a torque
required for operating the VVT by the energizing force of the
return spring. Consequently, it is possible to reduce a load of the
VVT required for changing a rotation phase of the camshaft, thereby
operating the VVT with a high responsiveness without requiring an
increase in a size and a rise in oil pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a typical diagram showing an example of a
schematic structure of a hydraulic circuit for an internal
combustion engine according to the present embodiment.
[0016] FIG. 2 is a sectional side view showing a structure of an
oil passage between an OCV and an exhaust side VVT.
[0017] FIG. 3 is a sectional plan view showing an internal
structure of the exhaust side VVT.
[0018] FIG. 4 is a typical diagram showing another example of the
structure of the hydraulic circuit for the internal combustion
engine according to the present embodiment.
[0019] FIG. 5 is a diagram showing a passage for oil in an
engine.
[0020] FIG. 6 is a diagram showing a passage for oil in an engine
using a VVT.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021] An embodiment according to the present invention will be
described below with reference to the drawings. FIG. 1 is a typical
diagram showing an example of a schematic structure of a hydraulic
circuit for an internal combustion engine according to the present
embodiment. In FIG. 1, components having the same reference
numerals as those shown in FIG. 5 have the same functions.
[0022] In FIG. 1, a first oil pump 12 sucks oil from an oil pan 11
and supplies the oil to a main gallery 14 through an oil filter 13.
In other words, the oil stored in the oil pan 11 is sucked by the
first oil pump 12 and is pressure fed to the main gallery 14
through the oil filter 13. Then, the oil is supplied from the main
gallery 14 to various mechanism units 15, and finally drops by its
own weight and returns to the oil pan 11.
[0023] Moreover, a second oil pump 21 sucks the oil from the main
gallery 14 and supplies the oil to an exhaust side VVT 24 through
an OCV 22. The exhaust side VVT 24 changes a rotation phase of an
exhaust side camshaft 26 with respect to a crankshaft (not shown)
to an advance angle side and a delay angle side, thereby
controlling a valve timing of an exhaust valve (not shown) to be
opened/closed by the exhaust side camshaft 26.
[0024] An intake side camshaft 25 and the exhaust side camshaft 26
are supported rotatably by an intake side cylinder head 27 and an
exhaust side cylinder head 28, respectively. In the present
embodiment, the exhaust side camshaft 26 is provided with the
exhaust side VVT 24. Moreover, the second oil pump 21 is connected
to the exhaust side camshaft 26 to obtain the driving force of the
second oil pump 21 from the exhaust side camshaft 26 (which will be
described below in detail).
[0025] FIG. 2 is a sectional side view showing a structure of an
oil passage between the OCV 22 and the exhaust side VVT 24.
Moreover, FIG. 3 is a sectional plan view showing an internal
structure of the exhaust side VVT 24. As shown in FIG. 2, the
exhaust side VVT 24 includes a housing 31, a rotor 32, a return
spring 33 and a gear 34. The rotor 32 is connected to the exhaust
side camshaft 26 and is thus rotated.
[0026] As shown in FIG. 3, the housing 31 has four spaces into
which four protruded vanes provided in the rotor 32 are to be
inserted. The vanes of the rotor 32 are configured rotatably to an
advance angle side and a delay angle side within a range shown in
an arrow A. Each of the four spaces is divided into an advance
angle hydraulic chamber 35a and a delay angle hydraulic chamber 35b
by the vanes of the rotor 32. The advance angle hydraulic chamber
35a and the delay angle hydraulic chamber 35b communicate with the
OCV 22 through an advance angle oil passage 37 and a delay angle
oil passage 38 respectively as shown in FIG. 2. The OCV 22 switches
a supply-exhaust state of oil with respect to the advance angle
hydraulic chamber 35a and the delay angle hydraulic chamber
35b.
[0027] For example, it is assumed that the oil is supplied from the
OCV 22 to the advance angle hydraulic chamber 35a through the
advance angle oil passage 37, and furthermore, the oil is returned
from the delay angle hydraulic chamber 35b to the OCV 22 through
the delay angle oil passage 38 and oil pressure is thus applied to
the advance angle hydraulic chamber 35a. In this case, the rotor 32
is rotated toward an advance angle side (the delay angle hydraulic
chamber 35b side) by energizing force based on the oil pressure in
the advance angle hydraulic chamber 35a. FIG. 3 shows a state in
which the oil pressure is applied to the advance angle hydraulic
chamber 35a so that the vanes of the rotor 32 are moved to a most
advance angle side.
[0028] The rotor 32 is rotated to the advance angle side so that
the rotation phase of the exhaust side camshaft 26 is changed. As a
result, a valve timing of an exhaust valve (not shown) to be
opened/closed by the exhaust side camshaft 26 is advanced in an
angle corresponding to the same phase as compared with a real
situation.
[0029] On the other hand, it is assumed that the oil is supplied
from the OCV 22 to the delay angle hydraulic chamber 35b through
the delay angle oil passage 38, and furthermore, the oil is
returned from the advance angle hydraulic chamber 35a to the OCV 22
through the advance angle oil passage 37 and oil pressure is thus
applied to the delay angle hydraulic chamber 35b. In this case, the
rotor 32 is rotated to the delay angle side (the advance angle
hydraulic chamber 35a side) by energizing force based on the oil
pressure in the delay angle hydraulic chamber 35b.
[0030] The rotor 32 is rotated to the delay angle side so that the
rotation phase of the exhaust side camshaft 26 is changed. As a
result, a valve timing of an exhaust valve (not shown) to be
opened/closed by the exhaust side camshaft 26 is delayed in an
angle corresponding to the same phase as compared with a real
situation. When the oil pressure to be applied to the advance angle
hydraulic chamber 35a and the delay angle hydraulic chamber 35b is
held by the OCV 22, the rotation phase of the exhaust side camshaft
26 is also held exactly.
[0031] The return spring 33 is configured like a coil, and has one
of ends fixed to the housing 31 with a body fixing hook 33a and the
other end fixed to the rotor 32 with a rotor fixing hook 33b as
shown in FIG. 3. Consequently, the return spring 33 is energized in
such a manner that the rotor 32 is held in a most advance angle
state (a state shown in FIG. 3) in stoppage of the engine (when the
oil pressure is not applied).
[0032] A timing belt (not shown) is laid over the gear 34 and
rotating force is transmitted from the crankshaft to the exhaust
side camshaft 26 through the timing belt and the gear 34.
[0033] In the present embodiment, in the intake side camshaft 25
and the exhaust side camshaft 26, the second oil pump 21 is
connected to the exhaust side camshaft 26 to which the rotor 32 is
connected so that the driving force of the second oil pump 21 is
obtained from the exhaust side camshaft 26. In other words, the
exhaust side camshaft 26 is rotated upon receipt of the
transmission of the rotating force from the crankshaft through the
timing belt. The second oil pump 21 is driven with the rotating
force of the exhaust side camshaft 26 set to be power, and sucks
the oil from the main gallery 14 and supplies the oil to the OCV
22.
[0034] According to the present embodiment having such a structure,
it is possible to reduce an increase in a torque required for
operating the exhaust side VVT 24 by the energizing force of the
return spring 33. Consequently, it is possible to reduce a load of
the exhaust side VVT 24 required for changing the rotation phase of
the exhaust side camshaft 26, thereby operating the exhaust side
VVT 24 with a high responsiveness without requiring an increase in
a size and a rise in oil pressure.
[0035] Although the description has been given to the example in
which the exhaust side VVT 24 having the rotor 32 and the return
spring 33 is provided on the exhaust side camshaft 26 and the
driving force of the second oil pump 21 is obtained from the
exhaust side camshaft 26 in the embodiment, the present invention
is not restricted thereto.
[0036] For example, as shown in FIG. 4, it is also possible to
employ a structure in which both the intake side camshaft 25 and
the exhaust side camshaft 26 are provided with the VVTs 23 and 24.
In this case, the second oil pump 21 sucks the oil from the main
gallery 14 and supplies the oil to the intake side VVT 23 and the
exhaust side VVT 24 through the OCV 22. The intake side VVT 23 and
the exhaust side VVT 24 change the rotation phases of the intake
side camshaft 25 and the exhaust side camshaft 26 with respect to
the crankshaft (not shown) to the advance angle side and the delay
angle side, thereby controlling the valve timings of the intake
valve and the exhaust valve (neither of them are shown) to be
opened/closed by the intake side camshaft 25 and the exhaust side
camshaft 26.
[0037] The intake side VVT 23 shown in FIG. 4 also includes a rotor
and a return spring for energizing to hold the rotor in a most
delay angle state in the stoppage of the engine. Also in this case,
the driving force of the second oil pump 21 is obtained from the
exhaust side camshaft 26 to which the exhaust side VVT 24 is
connected. It is also possible to obtain the driving force of the
second oil pump 21 from the intake side camshaft 25 to which the
intake side VVT 23 is connected. In the case in which the driving
force of the second oil pump 21 is obtained from the intake side
camshaft 25, the second oil pump 21 is preferably connected to the
intake side camshaft 25.
[0038] Moreover, it is also possible to employ a structure in which
the intake side VVT 23 is provided in only the intake side camshaft
25. In this case, the second oil pump 21 is connected to the intake
side camshaft 25, and sucks oil from the main gallery 14 and
supplies the oil to the intake side VVT 23 through the OCV 22.
Then, the driving force of the second oil pump 21 is obtained from
the intake side camshaft 25 to which the intake side VVT 23 is
connected.
[0039] In the embodiment, moreover, the description has been given
to the example in which the second oil pump 21 sucks the oil from
the main gallery 14 and supplies the oil to the exhaust side VVT 24
(both of the VVTs 23 and 24 in the case of FIG. 4). However, a
place where the second oil pump 21 sucks the oil is not restricted
to the main gallery 14. For example, the second oil pump 21 may
suck the oil from a downstream of the first oil pump 12 or may suck
the oil from the oil pan 11. Herein, the oil pressure required for
the second oil pump 21 is lower in the suction of the oil from the
downstream of the first oil pump 12 provided in an upper part of
the oil pan 11 than that in the suction of the oil from the oil pan
11. In this respect, it is preferable that the oil should be sucked
from the downstream of the first oil pump 12.
[0040] In addition, the embodiment is only illustrative for
concreteness to carry out the present invention and the technical
scope of the present invention should not be thereby construed to
be restrictive. In other words, the present invention can be
carried out in various configurations without departing from the
gist or main features thereof.
EXPLANATION OF DESIGNATION
[0041] 12 first oil pump
[0042] 14 main gallery
[0043] 21 second oil pump
[0044] 22 OCV
[0045] 23 intake side VVT
[0046] 24 exhaust side VVT
[0047] 25 intake side camshaft
[0048] 26 exhaust side camshaft
[0049] 32 rotor
[0050] 33 return spring
* * * * *