BACKGROUND OF THE INVENTION
a) Field of the Invention
[0001] The invention concerns an improved automatic starter provided on engines installed
in motorcycles, motor scooters, automobiles, etc. In particular, the present invention
concerns a compact automatic starter having an excellent thermal insulation around
a thermo-element provided in the automatic starter for the engines.
b) Description of Related Art
[0002] In an engine using gasoline as fuel which is mixed with air at a fixed fuel-to-air
ratio by a carburetor installed on the engine to feed into cylinders of the engine,
an automatic starter is normally provided on the engine in order to ease starting
the engine smoothly in a cold morning. The automatic starter is to increase the fuel-to-air
ratio for better ignition of a gas mixture of the fuel and the air in the cylinders
at low temperatures of the engine by actuating a valve to open a fuel-supply-inlet
of an auxiliary fuel passageway provided along a gas mixture passageway to add fuel
to the gas mixture flowing in the gas mixture passageway.
[0003] When the temperature of the engine reaches a predetermined operating temperature,
the fuel-supply-inlet of the auxiliary fuel passageway is closed to return the fuel-to-air
ratio to normal automatically.
[0004] The applicant previously proposed a type of automatic starter in Japanese Patent
Application No. Hei 5-253360. In the type of the automatic starter, the valve is actuated
by means of a thermo-element in which a thermally expanding unit expanding and contracting
with a change in the temperature is included to open and close a fuel-supply-inlet.
[0005] The expansion and contraction of the thermally expanding unit move a piston to actuate
a needle valve for opening and closing the fuel-supply-inlet.
[0006] While the temperature around the thermally expanding unit of the automatic starter
is low at the beginning of starting the engine, the thermally expanding unit is contracted
to keep the piston having the needle valve away from the fuel-supply-inlet and remain
open toward the auxiliary fuel passageway.
[0007] After the engine is warmed up above a predetermined temperature, the fuel-supply-inlet
should be closed forcibly by the needle valve. The automatic starter is provided with
a heating element on one side of the thermo-element to heat up the heating element
with heat generated by electric current when a key-switch is turned on to expand the
thermally expanding unit and move the piston having the needle valve to shut off the
fuel supply by closing the fuel-supply-inlet.
[0008] If the thermal insulation of the thermally expanding unit of the automatic starter
is poor, the thermally expanding unit remains contracted and the fuel-supply-inlet
is kept open to supply excessive fuel to the gas mixture passageway. As a result,
the engine cannot be re-started smoothly for a few minutes after the engine is turned
off. For this reason the conventional automatic starters are provided with a thermally
insulated cover each over the outer surface of the case body.
[0009] However, the thermally insulated cover over the outer surface of the case body makes
the automatic starter larger and requires much works for the assembly of the automatic
starter with a higher cost. A larger automatic starter hinders a freedom in designing
of a compact motor scooter which requires as large compartment underneath the seat
as possible for storing some items therein.
[0010] US-A-5 186 133 discloses an automatic starter for an engine comprising: a thermo-element
means having a thermally expanding unit; a heating means; and a case body in which
the thermo-element is housed.
[0011] Accordance to the present invention, an automatic starter for an engine as set forth
in claim 1 is provided. Preferred embodiments of the invention are disclosed in the
dependent claims.
Summary of the Invention
[0012] An objective of the present invention is to eliminate the thermally insulated cover
provided over the outer surface of the case body of the automatic starter in order
to obtain a compact automatic starter through fewer parts assembly and a greater freedom
in designing of a compact motor scooter, etc.
[0013] Another objective of the present invention is to improve the thermal insulation of
the thermally expanding unit of the thermo-element to enable smooth re-starting of
the engine.
[0014] The automatic starter according to the present invention is provided with a thermally
expanding unit, which expands and contracts with a change in the outer temperature,
on one side and a piston on the other side of a thermo-element which moves the piston
forward and backward. A heating unit is provided on the one side of the thermo-element
to forcibly move the piston. The heating unit is heated up by electric current turned
on with starting the engine to expand the thermally expanding unit and move the piston
to close a fuel-supply-inlet of an auxiliary fuel passageway provided along a gas
mixture passageway supplying the gas mixture to the engine.
[0015] The automatic starter according to the present invention as set forth above is formed
with a hollow in the wall of the case body of the automatic starter in which the thermo-element
is housed. The wall of the case body is divided into an inner wall and an outer wall
to form the hollow between the inner wall and the outer wall and a thermal insulation
is provided in the hollow, thereby thermal conduction from the inner wall to the outer
wall is reduced.
[0016] The automatic starter according to the present invention can reduce the heat radiation
from the surface of the case body more effectively by filling the air, a liquid or
a solid insulating material in the hollow formed in the case body.
[0017] Hence, the thermal insulation over the thermo-element can be achieved without the
thermally insulated cover over the outer surface of the case body and thus the construction
of the automatic starter can be more compact and less costly,
[0018] The automatic starter according to the present invention is provided with an excellent
thermal insulation and therefore the automatic starter can also eliminate the difficulty
in re-starting the engine for a few minutes after the engine is turned off by preventing
an excess supply of the fuel.
[0019] Other advantages of the automatic starter according to the present invention are
fewer parts assembly and a compact construction with less cost as well as a greater
freedom in designing of a compact motorcycle or motor scooter.
Brief Description of the Drawing
[0020] Figure 1 is a drawing showing a sectional side view of the automatic starter according
to the present invention.
[0021] Figure 2 is a plan drawing of the automatic starter according to the present invention.
Description of the Preferred Embodiments
[0022] The preferred embodiments of this invention are described hereunder by referring
to the accompanying drawings.
[0023] A case body 1 is a cylinder bended in an L-shape with both ends open having a heavy
thickness. An opening 1a of the one end of the case body 1 is provided with a thread
1c and a rubber grommet 11 is coupled into an opening 1b of the other end of the case
body 1 to prevent an entry of water or dust, etc. The opening 1a is coupled with a
cylindrical holder 2 on the outer surface of which a screw 2a is formed tomate with
the thread 1c. A thermo-element T moving a needle valve is included in the case body
1 and is held therein by the holder 2 not to remove therefrom.
[0024] The inner diameter of the case body 1 is tapered wider toward the opening 1a for
easy insertion of the thermo-element T and a bottom 1e is provided at the one end
of the thermo-element T in which a thermal sensor T having a thermally expanding unit
Ta is provided. The portion where the inner diameter of the case body 1 varies is
formed with a moderate slope 1d to guide the thermo-element T into the case body 1.
[0025] An 0-ring 9 is mounted on the outer surface of the thermal sensor T. The thermo-element
T is prevented from lateral movement in the case body by pushing the 0-ring against
the inner suface of the case body 1 as well as for the prevention of an entry of gasoline,
etc.
[0026] A heating means E having 2 electrodes and a heating element pinched between the 2
electrodes is provided between the thermal sensor T and the bottom 1e of the case
body 1.
[0027] The heating means E is to forcibly expand the thermally expanding unit Ta and is
connected with a key-switch (not shown) of a motor scooter, etc. by lead wires 12
and 12 of the electrodes coming out of the opening 1b through the grommet 11.
[0028] Upon insertion of a key into the key-switch (the engine is ready to start), an electric
current flows through the heating element to generate heat. A tube protector 13 is
to tie the lead wires 12 and 12.
[0029] The heating means E is formed with a holder having a cup-shape. A side view of the
holder is shown in Fig.1.
The 2 electrodes are housed in the holder which is provided with nails and cuts on
the edge of the holder in which the heating element is neatly placed and pinched between
the 2 electrodes and secured tightly on the cuts by the nails as a mono-block unit.
The holder is formed with an electrically insulated and elastic material such as nylon
to prevent a displacement or poor contact of the electrodes as well as for ready installation
of the heating means E. A piston 7b being moved with the expansion and contraction
of the thermally expandng unit Ta is properly guided by a piston guide 7a provided
on the other side of the thermo-element T.
[0030] The tip of the piston 7b is projected from the end of the piston guide 7a to slide
in the hole of the holder 2 and connected with a pushing unit 7 which covers the piston
guide 7a and the tip of the piston 7b. The pushing unit 7 is constantly pulled inward
in the case body 1 by a spring such as a coil spring 8 and thereby the thermo-element
T is pushed against the bottom 1e of the case body 1 to regulate a axial movement
of the thermo-element.
[0031] The thermally expanding unit Ta is expanded with the heat generated in the heating
unit E by the electric current and extend the piston 7b and push the pushing unit
7 out of the case body 1 by opposing the pulling force of the coil spring 8 to close
the fuel-supply-inlet with a needle valve (not shown) to shut off the fuel supply.
When the electric current to the heating means E is turned off, the temperature surrounding
the thermo-element T gradually goes down to contract the thermally expanding unit
Ta and the piston 7a moves backward. Then, the pushing unit 7 having the needle valve
is pulled back into the case body 1 to open the fuel-supply-inlet for fuel supply.
[0032] A hollow 6 is formed in the wall of the case body 1 circumferencially from the one
opening 1a to the other opening 1b.
[0033] The hollow 6 can be formed together with the case body 1 when the case body 1 is
formed through an injection molding process or after the case body 1 is molded the
hollow 6 can be formed by an end-milling or an arc-processing. A thermally insulating
means is provided in the hollow 6 to prevent the heat around the thermo-element T
from radiating from the surface of the case body 1.
[0034] Air is most common as a thermal insulator but other solid or liquid thermal insulators
such as urethane, foamed styrene, a rubber insulator or oil having low thermal conductivities
can be used for effective prevention of the heat radiation from the surface of the
case body 1.
[0035] The hollow 6 formed in the wall of the case body 1 divides the wall of the case body
1 into an inner wall 4 and an outer wall 3. The inner wall 4 is connected with the
outer wall 3 by way of a connector 5. The connector 5 is preferably formed as small
as possible within the range of permissible strength so that the thermal conduction
from the inner wall 4 to the outer wall 3 can be minimized.
[0036] The thermal insulators to prevent the thermal conduction from the inner wall 4 to
the outer wall 3 are not limited to such air, urethane, foamed styrene, insulating
rubber or oil as set forth in the above preferred embodiments.
[0037] For instance, both opening ends of the hollow 6 can be closed and the air is removed
therefrom to vacuum the hollow 6 for thermal insulation. Further, a gas such as nitrogen
can be charged in the hollow 6 for thermal insulation. Merely closing both opening
ends of the hollow 6 can shut off the air movement inward or outward for effective
reduction of the thermal conduction from the inner wall 4 to the outer wall 3.
1. Automatische Startvorrichtung für einen Motor, wobei folgendes vorgesehen ist: ein
Thermoelement (T) mit einer thermisch expandierenden Einheit (Ta), die sich ausdehnt
(expandiert) und zusammenzieht bei einer Änderung der Außentemperatur, vorgesehen
auf einer Seite des Thermoelements und eines Kolbens (7b), vorgesehen auf der anderen
Seite des Thermoelements, und zwar sich nach vorne und hinten bewegend mit der Ausdehnung
und dem Zusammenziehen der sich thermisch ausdehnenden Einheit, und ein Heizmittel
mit einer elektrischen Heizeinheit (E), vorgesehen an einer Seite des Thermoelements,
um durch Kraft den Kolben zu bewegen, und zwar durch Erhitzen der Heizeinheit mit
einem elektrischen Strom, der beim Starten des Motors fließt, um einen Brennstoffversorgungseinlass
eines Hilfsbrennstoffdurchlasses zu schließen, der entlang eines Gasmischungsdurchlasses
vorgesehen ist, der die Gasmischung zum Motor liefert, gekennzeichnet durch einen Hohlraum (6), vorgesehen in einer Wand des Gehäusekörpers (1), in dem das Thermoelement
untergebracht ist, um den Gehäusekörper in eine Innenwand (4) und eine Außenwand (3)
zu unterteilen und mit thermischen Isoliermitteln, vorgesehen in dem Hohlraum, um
die Wärme nicht von der Innenwand zur Außenwand zu leiten.
2. Automatische Startvorrichtung für den Motor gemäß Anspruch 1, wobei die Heizmittel
(E) einen Halter aufweisen und zwar ausgeformt mit einem elektrisch isolierenden und
elastischen Material und mit einer Schalenform, in der zwei Elektroden und eine Heizeinheit
eingeklemmt bzw. angeordnet zwischen den zwei Elektroden untergebracht sind und eine
Monoblockeinheit bilden.
3. Automatische Startvorrichtung für den Motor gemäß Anspruch 1, wobei der Hohlraum (6)
zwischen der Innenwand (4) und der Außenwand (3) des Gehäusekörpers (1) gebildet ist
und mit einem thermisch isolierenden Material angefüllt ist.
1. Starter automatique pour moteur comprenant un thermo-élément (T) comprenant un élément
thermiquement dilatable (Ta) qui se dilate et se contracte en fonction de changements
de la température externe monté d'un premier côté du thermo-élément et un piston (7b)
monté de l'autre côté du thermo-élément, qui se déplace vers l'avant et vers l'arrière
en fonction de la dilatation et de la contraction de l'élément thermiquement dilatable,
et un moyen de chauffage comportant un module de chauffage électrique (E) prévu du
premier côté du thermo-élément pour déplacer à force le piston en chauffant l'élément
de chauffage par un courant électrique qui circule au moment du démarrage du moteur
pour fermer une entrée d'alimentation de carburant d'un passage de carburant auxiliaire
prévu le long d'un passage de mélange de gaz qui fournit le mélange de gaz au moteur,
caractérisé en ce qu'un creux (6) est formé dans une paroi d'un corps de boîtier (1) dans lequel le thermo-élément
est logé pour diviser le corps du boîtier en une paroi interne (4) et une paroi externe
(3), et en ce qu'un moyen d'isolement thermique est prévu dans le creux pour ne pas conduire la chaleur
de la paroi interne vers la paroi externe.
2. Starter automatique pour moteur selon la revendication 1, dans lequel le moyen de
chauffage (E) est un support moulé avec un matériau élastique et électriquement isolant
et ayant une forme de coupe dans laquelle deux électrodes et un module de chauffage
pincés entre les deux électrodes sont logés, et formant un élément monobloc.
3. Starter automatique pour moteur selon la revendication 1, dans lequel le creux (6)
formé entre la paroi interne (4) et la paroi externe (3) du corps de boîtier (1) est
rempli d'un matériau thermiquement isolant.