Internal-combustion engines – Cooling – Automatic coolant flow control
Reexamination Certificate
1998-06-04
2001-04-24
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Cooling
Automatic coolant flow control
C123S041490
Reexamination Certificate
active
06220207
ABSTRACT:
TECHNICAL FIELD
1. Field of the Invention
The present invention relates to an engine cooling system, and more particularly to an engine cooling system mounted on construction machines.
2. Description of the Related Art
Of known art concerned with engine cooling system of the above-mentioned type, several conventional examples employing centrifugal fans are discussed below.
(1) “Internal Combustion Engine”, Vol. 31, No. 388, p. 9-27 (1992)
This known art intends to improve a cooling ability by using a centrifugal fan as a fan to supply cooling air in an engine cooling section of a construction machine, and to reduce noise of engine sound by separating an engine room and a cooling system section from each other.
(2) JP, A, 5-248239
This known art intends to improve a cooling ability by using a centrifugal fan as a fan to supply cooling air in an engine cooling section of a working vehicle such as a tractor.
(3) JP, U, 2-64799
This known art intends to eliminate a discharge duct, which has been required when using an axial fan, by using a centrifugal fan as a fan to supply cooling air in an engine cooling section of an automobile.
On the other hand, as known art concerned with engine cooling systems employing axial fans, there is an example set forth below.
(4) JP, A, 5-288053
According to this known art, in an engine cooling system for a hydraulic excavator, cooling air is supplied to a heat exchanger by an axial fan coupled to an engine crankshaft through a fan belt. Though not stated in detail in the Publication disclosing this known art, the engine cooling system has a structure, by way of example, as shown in FIG.
8
.
In
FIG. 8
, an engine cooling system is provided in an engine room
2
housing an engine
1
installed therein, and comprises an intercooler
3
for precooling combustion air supplied to the engine
1
, an oil cooler
4
for cooling a hydraulic working fluid for use in a hydraulic excavator, a radiator
5
for cooling cooling water supplied to the engine
1
, a cooling fan
8
in the form of an axial fan driven by a fan belt
7
to which power is transmitted from the crankshaft
6
of the engine
1
, and a suction duct
9
for introducing the cooling air to the suction side of the cooling fan
8
.
The cooling air enters the engine room
2
through a cooling air inlet port
10
from the outside of the engine room
2
, and is restricted by the suction duct
9
after passing the intercooler
3
, the oil cooler
4
and the radiator
5
which are each a heat exchanger, followed by reaching the cooling fan
8
. After being blown out axially to the downstream side of the cooling fan
8
, the cooling air flows around the engine
1
and an oil pan la below the engine
1
while cooling them, and is then discharged to the outside through cooling air outlet ports
11
,
12
disposed respectively in upper and lower portions of the engine room
2
. Additionally, the engine
1
is installed on a frame
13
, which is provided on a bottom surface
2
a
of the engine room
2
, through vibration damping devices
14
, and partition members
15
,
16
are disposed so as to provide sealing between the suction duct
9
and an upper cover
2
b
and the bottom surface
2
a
of the engine room
2
.
Further, as known art concerned with engine cooling system employing obliquely axial fans, there is an example set forth below.
(5) JP, A, 4-269326
This known art is to achieve a higher pressure and a higher flow rate than obtainable with an axial fan by using an obliquely axial fan as a fan to supply cooling air in a cooling section of a diesel engine for vehicles, and by simultaneously forming a fixed shroud for introducing the cooling air in the shape of a suction duct.
Recently, there has been a tendency that resistance of a cooling flow passage in an engine room is increased due to the provision of an intercooler, a demand for improved enclosing of the engine room for noise reduction, and a demand for a more compact structure of the engine room. Because a comparable flow rate to a conventional device is demanded in spite of such a tendency, a cooling fan is required to provide a larger flow rate and a higher pressure.
Responding to those needs, in the known arts (1) to (3), a centrifugal fan capable of providing a larger flow rate and a higher pressure than an axial fan on condition the of having the same outer diameter and the same revolution speed under action of centrifugal forces is employed as the cooling fan in place of the axial fan which has been hitherto usually employed. In a centrifugal fan, cooling air is introduced to a impeller axially from a suction duct and blown out radially upon rotation of the vane wheel, but on that occasion there occurs a leakage of the cooling air in the radial direction through gaps between the suction duct and vanes. This increases loss and hence raises the problem that the fan efficiency expressed by (flow rate×pressure)/(power input to fan rotary shaft) is lowered and noise is increased.
Further, in the known arts (4) and (5), the use of an axial fan or an oblique axial fan makes it difficult to achieve a sufficient increase in flow rate and pressure. Accordingly, there has been a problem that when trying to ensure the same flow rate as usual under a condition where the resistance of the cooling flow passage in the engine room is increased for the above-mentioned reason, the revolution speed must be raised; hence noise is increased. Additionally, in the known art (5), because an air flow having passed the axial fan flows in such a direction as to strike against the engine, a pressure loss is increased and a reverse flow of the cooling air occurs around the engine and the oil pan in some cases. For these reasons, it is hard to ensure a sufficient flow rate of the cooling air. As a result, the revolution speed must be further raised from the standpoint of ensuring a sufficient flow rate of the cooling air; hence noise is increased.
To solve the problems stated above, the inventors of this application have proposed, in Japanese Patent Application No. 7-109483 (filed May 8, 1995), an engine cooling system comprising at least one heat exchanger provided in an engine room housing an engine installed therein, and including a radiator to cool cooling water supplied to the engine, a fan for cooling the heat exchanger, and a suction duct provided upstream of the fan and introducing the cooling air to the suction side of the fan, wherein the cooling fan is one of a mixed flow fan or a centrifugal fan, and includes an impeller provided with a plurality of vanes, and a rotary shroud fixed to the impeller and rotated together with the vane wheel.
In the proposed engine cooling system, however, the relationship in arrangement between the rotary shroud and the suction duct is not specified. There is disclosed such a structure that a suction-side end of the rotary shroud is positioned on the outer side and a downstream end of the suction duct is positioned on the inner side, and a structure that the suction-side end of the rotary shroud is positioned on the inner side and the downstream end of the suction duct is positioned on the outer side. The engine cooling system having the above structure accompanies another problem below.
In general, a largest part of the noise generated by the cooling system of the above-mentioned type is from the impeller of the cooling fan, and a largest part of the noise generated from the impeller is from front edges of vanes (inlet of vane). When the downstream end of the suction duct is positioned outside the suction-side end of the rotary shroud, the direction of a gap flow coming in through radial gaps between the suction duct and the rotary shroud is opposed to the direction of a main flow of cooling air coming in from the suction duct to the rotary shroud, and the flow of the cooling air is greatly disturbed due to eddies or the like in a joining area of both the gap flow and the main flow. A turbulent flow thus generated increases noise, in particular, at the vane front edges of the vane wheel. Further, in the above a
Funabashi Shigehisa
Kanahara Masaki
Kaneko Zenji
Kawasaki Koji
Tahara Koji
Benton Jason
Hitachi Construction Machinery Co. Ltd.
Mattingly, Stanger & Malur
McMahon Marguerite
LandOfFree
Engine cooling apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Engine cooling apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Engine cooling apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550956