Internal-combustion engines – Igniters – Incandescent
Reexamination Certificate
2002-06-24
2003-11-18
Vo, Hieu T. (Department: 3747)
Internal-combustion engines
Igniters
Incandescent
Reexamination Certificate
active
06647937
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a glow plug energization controlling device which controls energization of a glow plug used for a preheating apparatus of a diesel engine, not only at the time of starting but also at the time of driving.
BACKGROUND OF THE INVENTION
Diesel engines are widely used not only for vehicles but also for ships, and when used for ships, they are commonly called marine engines.
In order to make starting of such a diesel engine easy, various types of preheating apparatuses have been invented and have been provided for practical use. A preheating apparatus using a glow plug is the most general one.
This preheating apparatus inserts a glow plug in a combustion chamber of a diesel engine, and energizes the glow plug at the time of starting at which time fuel is hard to burn. If the glow plug is heated red hot by energization, the fuel injected by cranking of a starter is heated by the glow plug and becomes easy to burn, and starting is easily carried out.
Control of energization of the glow plug is carried out in relation to the operation of a key switch at the time of starting, and when starting is completed, usually, energization of the glow plug is stopped. However, even if starting is completed, the fuel is not necessarily always easy to burn. If the intake air temperature is low because the ambient temperature is low, or if the temperature of the engine hardly increases while driving after starting, the combustion state does not improve, and a rise of engine speed does not quickly occur. Further, the fuel which cannot be burned is exhausted as blue-white smoke, and that fuel mist adheres to and accumulates at an exhaust pipe.
For example, in a case where a diesel engine with a turbo-supercharger is used in a ship and the compression ratio is set to be small or the like, it frequently occurs that the combustion state worsens at the time of driving. If an attempt is made to output high power by such an engine, it is necessary to carry out high-supercharging, and therefore, the compression ratio must be small. However, in an engine having a small compression ratio, even if the temperature of the engine rises, the temperature of a combustion chamber does not rise much at the time of low-speed/low-load driving, and blue-white smoke, fuel mist, and an offensive smell are generated.
In the case of a ship or the like, if blue-white smoke is exhausted or a peculiar offensive smell is emitted, the crew, may become ill, and the fuel mist contaminates the ocean.
Note that the time of low-speed/low-load driving is, in other words, a time when extremely low-speed sailing is carried out due to idle driving.
Such a state arises, for example, when a fishing vessel sails at an extremely low-speed for operation or the like after reaching a desired water area or the like. If the operating time is long, idle driving is carried out for a long time. In a ship, unlike a vehicle, there are many cases in which cooling of an engine is carried out by a heat exchanger or directly by sea water. Therefore, the degree of lowering of the temperature of the combustion chamber is large, and the combustion state is worse than in the case of a vehicle.
Further, at the time of idle driving with no load (at the time of berthing), the combustion state deteriorates.
Due to this, of course, preheating of a diesel engine is carried out so as to raise the temperature and to easily carry out starting in as short time as possible at the time of starting. While driving after starting, it is desirable that the temperature is maintained at a temperature at which combustion is satisfactorily carried out.
Here, a structure has been proposed in which, initially, glow plugs are connected in parallel and are heated rapidly by heavy electric current being made to flow at the battery voltage, and then, after switching to a series connection, the same voltage is applied and light electric current for temperature maintenance is made to flow.
FIG. 2
is a diagram showing such a conventional glow plug energization controlling device (Japanese Patent Application Laid-Open No. 8-240173). In
FIG. 2
, the reference numeral
1
designates a battery, the reference numeral
3
designates a key switch, the reference numeral
4
designates a starter, the reference numerals
5
A and
5
B designate glow plugs, the reference numeral
10
designates a switching relay, the reference numeral
10
-
1
designates a movable contact, the reference numeral
10
-
2
designates a relay coil, the reference numerals D and E designate fixed contacts, the reference numeral
11
designates an engine speed sensor, the reference numeral
12
designates an exhaust temperature sensor, and the reference numeral
16
designates a glow display lamp.
The glow display lamp
16
is a lamp for displaying whether or not the glow plugs
5
A,
5
B are energized.
The switching relay
10
is a relay for making the glow plugs
5
A,
5
B, which are divided into two groups, parallel connection and series connection. When the relay coil
10
-
2
is de-energized, the movable contact
10
-
1
contacts the fixed contact D as shown by the solid line, and the glow plugs
5
A,
5
B are connected in parallel. When the relay coil
10
-
2
is energized, the movable contact
10
-
1
contacts the fixed contact E as shown by the dotted line, and the glow plugs
5
A,
5
B are connected in series. The glow plugs
5
A,
5
B are connected in parallel at the time of starting, and are connected in series at the time of energizing while driving.
Note that, in the case of the glow plug energization controlling device of
FIG. 2
in a marine engine, as the glow plugs
5
A,
5
B, two-wire type glow plugs having 24V specifications are used for rapid heating. This glow plug is not a mass-produced product (standard product) for vehicles which are on the market generally, but is specially designed.
FIG. 5
is a view showing a two-wire type glow plug. The reference numeral
14
designates an engine body, the reference numeral
15
designates a two-wire type glow plug, the reference numeral
15
-
1
designates a conductive wire, the reference numeral
15
-
2
designates a metal case, the reference numeral
15
-
3
designates a heater coil, the reference numeral
15
-
4
designates an insulator, the reference numeral
15
-
5
designates a glow plug body, and the reference numeral
17
-
1
and
17
-
2
designate connectors.
In the two-wire type glow plug
15
, both ends of the heater coil
15
-
3
are respectively connected to the connectors
17
-
1
,
17
-
2
via the conductive wire
15
-
1
.
Although the relay coil
10
-
2
of the switching relay
10
is energized by a signal from the controller
7
, it is not energized at the time of starting. The control of energizing and de-energizing the relay coil
10
-
2
is carried out at the time of driving after starting. Energizing and de-energizing of the relay coil
10
-
2
are determined by a detection signal from the engine speed sensor
11
or the like, and the like.
The operations of the device of
FIG. 2
are as follows.
(1) At the Time of Starting
FIG. 3
is a table of key switch connection at the time of starting. When the key switch
3
is at a “preheating” position, a B terminal connected to the battery
1
is connected to an R
1
terminal. Because the R
1
terminal is connected to the glow plugs
5
A,
5
B connected in parallel, battery voltage is applied thereto.
Next, the key switch
3
is rotated via the “OFF” position and the “ON” position to the “starting” position. There, the B terminal is connected to an R
2
terminal, a C terminal, and an ACC terminal. Because the R
2
terminal is connected, collectively with the R
1
terminal, to the glow plugs
5
A,
5
B connected in parallel, battery voltage is applied to the glow plugs
5
A,
5
B, respectively. At the time of starting, it is demanded that large electric current flows to the glow plugs and the glow plugs are immediately heated.
On the other hand, electric current flows from the C terminal to the starter
4
, and cranking is carried out. At the
Huynh Hai H.
Isuzu Motor Limited
Rabin & Berdo PC
Vo Hieu T.
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