Title of Invention

"STARTING FUEL REGULATOR FOR CARBURETOR"

Abstract A starting fuel regulator for a carburetor, the starting fuel regulator comprising: a throttle valve (23) for controlling an open area of a starting air intake path (15i, 152, 153) communicating with upstream and downstream ends of a main air intake path (13) formed in a carburetor body (10); thermosensitive driving means (25) for operating the throttle valve (23) in accordance with expansion or contraction of wax (50) with temperature variations, the wax (50) being housed in a casing (46) fitted in a carburetor body (10); and an electric heater (26) for heating the wax (50) and being coupled to the casing (46), characterized in that the carburetor body (10) has an upstream opening amount adjusting region (18i, I82, I83) communicating with an upstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153), a downstream opening amount adjusting region (191, 192, 193) communicating with a downstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153), and a hollow (20), the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193) confronting each other via the hollow (20), the throttle valve (23) is slidably fitted in the hollow (20) and controls open areas of the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193), and a bottom of the downstream opening amount adjusting region (191, 192, 193) is located a predetermined height difference lower than a bottom of the upstream opening amount adjusting region (181, 182, 183).
Full Text [Field of the Invention]
The present invention relates to a starting fuel regulator for a carburetor.
The starting fuel regulator comprises: a throttle valve for controlling an open area of a starting air intake path communicating with upstream and downstream ends of a main air intake path formed in a carburetor body; thermosensitive driving means for operating the throttle valve in accordance with expansion or contraction of wax with temperature variations, the wax being housed in a casing fitted in the carburetor body; and an electric heater coupled to the casing in order to heat the wax.
[Description of the Related art]
The foregoing starting fuel regulator is well-known and is disclosed, for example, in Japanese utility Model publication No. Hei 3-6844.
The application is a co-pending application of Indian Patent application no. 1688/DEL/97.
[Problems to be solved by the Invention]
In the related art, a sleeve, which includes a port communicating with upstream and downstream ends of a main air intake path, is forcibly fitted into a carburetor body. A throttle valve is slidably fitted in the sleeve in order to control open areas of the foregoing ports. Therefore, this means an increase in the number of components to be used, and the need to assemble the sleeve into the carburetor body. An air introducing area will inevitably vary between the carburetor body and the sleeve due to errors of manufactured sleeves and errors caused when assembling a sleeve into the carburetor body. Variation of the air introducing area may adversely affect the control of an amount and concentration of an air-fuel mixture.
The present invention is aimed at overcoming the foregoing problems of the related art, and at providing a starting fuel regulator for a carburetor, which can reliably control the amount and concentration of a starting air-fuel mixture, as well as enabling a reduction in the number of components.

Accordingly, there is provided a starting fuel regulator for a carburetor, the starting fuel regulator comprising: a throttle valve (23) for controlling an open area of a starting air intake path (15i, 152, 153) communicating with upstream and downstream ends of a main air intake path (13) formed in a carburetor body (10); thermosensitive driving means (25) for operating the throttle valve (23) in accordance with expansion or contraction of wax (50) with temperature variations, the wax (50) being housed in a casing (46) fitted in a carburetor body (10); and an electric heater (26) for heating the wax (50) and being-coupled to the casing (46), characterized in that the carburetor body (10) has an upstream opening amount adjusting region (181, 182, 183) communicating with an upstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153), a downstream opening amount adjusting region (191, 192, 193) communicating with a downstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153), and a hollow (20), the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193) confronting each other via the hollow (20), the throttle valve (23) is slidably fitted in the hollow (20) and controls open areas of the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193), and a bottom of the downstream opening amount adjusting region (191, 192, 193) is located a predetermined height difference lower than a bottom of the upstream opening amount adjusting region (181, 182, 183).
[Means to solve the Problems]
In the invention disclosed in claim 1, there is provided a starting
fuel regulator for a carburetor, comprising: a throttle valve for
controlling an open area of a starting air

intake path communicating with upstream and downstream ends of a main air intake path formed in a carburetor body; thermosensitive driving means for operating the throttle valve in accordance with expansion or contraction of wax with temperature variations, the wax being housed in a casing fitted in a carburetor body; and an electric heater for heating the wax and being coupled to the one end of the casing. The carburetor, body has an upstream opening amount adjusting region communicating with an upstream end of the main air intake path and constituting a part of the starting air intake path, a downstream opening amount adjusting region communicating with a downstream end of the main air intake path and constituting a part of the starting air intake path, and a hollow. The upstream and downstream opening amount adjusting regions confront each other via the hollow. The throttle valve is slidably fitted in the hollow and directly controls open areas of the upstream and downstream opening amount adjusting regions. A bottom of the downstream opening amount adjusting region is located a predetermined height difference lower than a bottom of the upstream opening amount adjusting region.
In the invention disclosed in claim 2, in addition to the configuration.of the invention disclosed in claim 1, when the carburetor body is cast, the upstream opening amount adjusting region and the downstream opening amount adjusting region are formed as cast holes by pulling cores in a direction from the upstream opening amount adjusting region to the downstream opening amount adjusting region, or after the carburetor body is cast, the upstream opening amount adjusting region and the downstream opening amount adjusting region are bored from a side of the downstream opening amount adjusting region.
[0007]
In the invention disclosed in claim 3, in addition to the configuration of the invention disclosed in claim 2, the

cores are pulled in a direction which is parallel to one of the directions in which a die for the carburetor body is pulled.
In the invention disclosed in claim 4, in addition to the configuration of the invention disclosed in claim 2, the starting air intake path comprises an upstream path having an upstream end communicating with the upstream end of the main air intake path, a downstream path having a downstream end communicating with the downstream end of the main air intake path, the upstream opening amount adjusting region communicating with the downstream end of the upstream path faces the hollow, and the downstream opening amount adjusting region communicating with the upstream end of the downstream path faces the hollow. Inner diameters of the upstream opening amount adjusting region and the downstream opening amount adjusting region are larger than inner diameters of the upstream path and the downstream path.
[Brief Description of the Drawings]
Fig. 1 is a cross section of a starting fuel regulator according to a first embodiment, taken along line 1-1 in Fig.
2.
Fig. 2 is a cross section taken along line 2-2 in Fig. 1.
Fig. 3 is an enlarged cross section taken along line 3-3 in Fig. 2.
Fig. 4 is a graph showing characteristics of an air flow-rate in response to the operation of a throttle valve.
Fig. 5 is a graph showing the relationship between ambient temperature and air-to-fuel ratio.
Fig. 6 is a section showing a part of a carburetor immediately after it is cast.
Fig. 7 is a graph showing an operated amount of the throttle valve in accordance with temperature variations.
Fig. 8 is a cross section of a carburetor body to which a second embodiment of the invention is applicable.
Fig. 9 is an enlarged section taken along line 9-9 in Fig. 8.
Fig. 10 is a cross section of a carburetor body to which a third embodiment of the invention is applicable.

[Description of Embodiments]
The invention will be described with reference to embodiments shown in the accompanying drawings. [0010]
Fig. 1 to Fig. 7 show a first embodiment of the invention. Specifically, Fig. 1 is a section of a starting fuel regulator, taken along line 1-1 in Fig. 2. Fig. 2 is a cross section of a carburetor body, taken along line 2-2 in Fig. 1. Fig. 3 is an enlarged section taken along line 3-3 in Fig. 2. Fig. 4 is a graph showing characteristics of airflow rate in accordance with the operation of a throttle valve. Fig. 5 is a graph showing the relationship between an ambient temperature and air-to-fuel ratio. Fig. 6 is a section of a carburetor body immediately after it is cast. Fig. 7 is a graph showing an operated amount of the throttle valve in accordance with temperature variations. [0011]
Referring to Figs. 1 and 2, a float chamber 12 defined by a float chamber body 11 is coupled to a carburetor body 10 to be mounted in a motor cycle. The float chamber body 11 is made of light metal such as aluminum alloy, and is made by diecasting.
The carburetor body 10 includes a main air intake path 13, and a starting air intake path 151 communicating with
upstream and downstream ends of the main air intake path 13
in an air intake direction 14. A starting fuel regulator 21 is disposed within the starting air intake path 15\.
[0013]
The starting air intake path 15i includes: an upstream
portion 16 which communicates with the upstream end of the air intake path 13, extends linearly from the main air intake path 13 toward a downstream side, and has a circular cross section; a downstream path 17 which communicates with the downstream end of the main air intake path 13 and extends linearly from the main air intake path 13 toward an upstream side; an upstream opening amount adjusting region 18i
communicating with an upper end of the upstream portion 16; and a downstream opening amount adjusting region 19communicating with the a lower end of the downstream path 17.
The upstream and downstream opening amount adjusting region 181 and 191 are parallel to the main air intake path 13, and
are spaced away from the main air intake path 13 at their upstream and downstream ends.
[0014]
The starting fuel regulator 21 comprises a starting fuel nozzle 22, a throttle valve 23 for adjusting an open area of the starting air intake passage 15, a needle valve 24 supported by the throttle valve 23 and being movable in the starting fuel nozzle 22, a thermosensitive driver 25 for operating the throttle valve 23, and a PTC type electric heater 26 coupled to one end of a casing 46 of the thermosensitive driver 25.
[0015]
The throttle valve 23 is fitted in a hollow 20 in the carburetor body 10. The hollow 20 has a circular cross section, and is orthogonal to the upstream and downstream opening amount adjusting regions 18i and 19\, so that these opening amount adjusting regions 18\ and 19i open on an inner
surface of the hollow 20 and face each other via the hollow 20.
[0016]
A starting fuel chamber 28 is formed between the carburetor body 10 and the float chamber body 11, and extends coaxially with the hollow 20. The starting fuel chamber 28 communicates with the hollow 20 via a diaphragm 27 at the bottom of the hollow 20. The starting fuel nozzle 22 is fitted and fixed in a hole 29 on the diaphragm 27, and extends into the starting fuel chamber 28 at its lower end. The upper end of the starting fuel nozzle 22 is positioned slightly above the bottom of the hollow 20.
The float chamber body 11 includes a fuel jet 30 which is forcibly fitted and fixed therein, and communicates with the lower part of the starting fuel chamber 28 and the lower part of the float chamber 12. The carburetor body 10 includes a path 31 communicating with the float chamber 12 at an area above a fuel level L and the upper part of the starting fuel chamber 28.
The upstream and downstream opening amount adjusting regions 181 and 191 have cross sectional shapes as shown in
Fig. 3. Specifically, the opening amount adjusting regions 181 and 191 have semi-circular upper portions 18a and 19a and
lower elongate oval portions 18b and 19b extending from the upper portions 18a and 19a along the periphery of the hollow 20. The lower oval portions 18b and 19b are wider than the upper portions 18a and 19a in a direction orthogonal to the periphery of the hollow 20, i.e. in the moving direction of
the throttle valve 23. Further, the bottom of the downstream opening amount adjusting region 191, i.e. the bottom of the
lower elongate oval portion 19b, is located a height difference h lower than the bottom of the upstream opening amount adjusting region 181 (i.e. the bottom of the lower
elongate oval portion 18b).
The upstream and downstream opening amount adjusting regions 181 and 191 enable the open area of the starting air intake passage 151 to be relatively large when an ambient temperature is relatively high. Referring to Fig. 4, an
amount of air introduced via the starting air intake passage 151 can be increased (shown by a solid line) compared with
when the upstream and downstream opening amount adjusting regions 181 and 191 are coaxial with each other and have
completely circular cross sections (shown by a dashed line). Thus, it is possible to effectively prevent the air-fuel mixture from becoming too rich, and to improve the starting efficiency of the engine during hot weather.
[0020]
It is assumed that the throttle valve 23 gradually closes the upstream and downstream opening amount adjusting regions 181 and 191 as the ambient temperature rises. If the opening amount adjusting regions 181 and 191 are
simultaneously closed since there is no height difference
therebetween, a negative pressure acting on the starting fuel
nozzle 22 will be reduced. This causes a reduced amount of
fuel to be sucked in, which will lead to a steep decrease in
the air-to-fuel ratio, as shown by a dashed line in Fig. 5.
However, the bottom of the downstream opening amount adjusting region 191 is lower by the height difference h than
the bottom of the upstream opening amount adjusting reyion 181 Thus, the downstream side opening amount adjusting region 191 remains slightly open even when the opening amount adjusting region 181 is closed. Thus, an area upstream from
the starting fuel nozzle 22 is subject to choking in order to
raise the negative pressure acting on the starting fuel nozzle 22 and to prevent a sudden fall of the air-to-fuel ratio, as shown by a solid line in Fig. 5.
Not only the upstream and downstream opening amount adjusting regions 181 and 191 having the special shapes but
also a circular opening 32 on a side of the carburetor body
10 are formed using cores (not shown) when the carburetor
body 10 is cast. Refer to Fig. 6. The opening amount adjusting regions 181, 191 and the circular hole 32 should be
parallel to the main air intake path 13. In other words,
when the carburetor body 10 is cast, the opening amount adjusting regions 181, 191 and the circular hole 32 are
formed by pulling the cores in the direction (shown by an
arrow 34) from the upstream opening amount adjusting region 181 to the downstream opening amount adjusting region 19i,
i.e. in a direction parallel to the direction in which the core for the main air intake path 13 is pulled. Further, a cast hole 20 which is smaller than the hollow 20 is formed in the carburetor body 10 together with the upstream and downstream opening adjusting regions 181 and 19lf and the circular hole 32. The cast hole 20' is shaved in order to form the hollow 20. The circular hole 32 is blocked by a ball 33 forcibly fitted thereinto, as shown in Figs. 1 and 2.
Returning back to Fig. 1, the throttle valve 23 has a support plate 35 near its bottom as an integral member. A needle valve 24 passes through the support plate 35, and has a stop ring 36 attached at its top. The stop ring 36 is engaged with the upper surface of the support plate 35, and is pressed to the support plate 35 by a spring 37, so that the needle valve 24 is held by the throttle valve 23. The throttle valve 23 has at its top a brim 38 radially extending toward its center. A projection 40 which is present at the lower end of a set collar 39 is engageable with the lower surface of the brim 38. The spring 37 is disposed, in a

contracted state, between the set collar 39 and the stop ring 36, urging the stop ring 39 toward the support plate 35, and enabling the projection 40 to be engaged with the brim 38. [0023]
In the carburetor body 10, a retaining canister 41 larger than the hollow 20 is present around the hollow 20, is coaxial with the hollow 20, and forms a step 42 surrounding the periphery of the hollow 20. The retainer 43 extending in the sliding direction of the throttle valve 23 is fitted in the retaining canister 41 such that the base of the retainer 43 comes into contact with the step 42. A stop 44 is fixedly attached to the top of the retaining canister 41 by a screw member (not shown). The stop 44 is engaged with a regulating step 45 surrounding the periphery of the retainer 43. Thus, the base of the retainer 43 is fixedly attached to the carburetor body 10. [0024]
The thermosensitive driver 25 includes a casing 46 which is housed in the retainer 43 with one end projecting from the retainer 43. The casing 46 includes a cylindrical case main body 47 which has a step made of a conductive metal, and a cap member 48 which is made of conductive metal, and is coupled and caulked to one end of the case main body 47. The periphery of the diaphragm 49 is sandwiched between the case main body 47 and the cap member 48. Thus, the electric PTC type heater 26 comes into contact with one end of the casing 46 or the cap member 48. [0025]
Wax 50 is housed between the cap member 48 and the diaphragm 49. Within the case main body 47 there is a non-rigid member 51 such as rubber, silicone or the like contacting the diaphragm 49 on the opposite side to the wax 50, a sealant 52, and a piston 53, all of which are arranged one on top of the other. The piston 53 partially projects from the casing 46, i.e. the other end of the main body 47. [0026]

The casing 46 is air-tightly fitted into the retainer 43 with the cap member 48 projecting from the end of the retainer 43. In the retainer 43, the case main body 47 is fitted and is slidable in the upper part of the set collar 39. The piston 53 is coaxial with the set collar 39, and an end of the piston 53 projecting from the casing 46 is in contact with the set collar 39. A spring 54 is inserted, in a contracted state, between the base of the retainer 43 and the set collar 39. The spring 54 urges the casing 46 upward via the set collar 39 and the piston 53, so that the piston 53 is in continuous contact with the set collar 53. Thus, the piston 53 is interlocked with the throttle valve 23 via the set collar 39, thereby being operable through the throttle valve 23. [0027]
A synthetic resin cover 55 is detachably attached to the retainer 43, and includes a tubular member 56 surrounding the retainer 43, one end of the casing 46 and the PTC type heater 26. The cover 55 is screwed to the retainer 43, for example.
The tubular member 56 includes a cylindrical portion 56a surrounding the retainer 43 and an end wall portion 56b stopping the end of the cylindrical portion 56a. The end wall portion 56b is thicker than the cylindrical portion 56a, and functions as a heat accumulator.
The end wall portion 56b has, on its inner surface, a cavity 57 for receiving one end of the casing 46 (i.e. a part of the cap member 48), and a cavity 58, and a cylindrical projection 59. The cavity 58 is smaller than the cavity 57, and is coaxial with the cavity 57. The top of the cylindrical projection 59 is flush with the bottom of the cavity 57. [0030]
A hole 60 is formed in an area where the cylindrical portion 56a and the end wall portion 56b join with each other.

The cylindrical projection 59 is fitted into the hole 60, so that a heater terminal 62 can be fitted into the cover 55 without becoming loose. Further, the end wall portion 56b has a hole 61 for receiving a heater terminal 63. The heater terminal 63 has a claw 63a which elastically engages in and disengages from the cavity 58. Thus, the heater terminal 63 can be fitted into the cover 55 without becoming loose.
The cap member 48 is fitted in the cavity 57 so as to sandwich the PTC type heater 26 between itself and the heater terminal 63. Since the casing 46 is urged upward by the spring 54, the heater terminal 63 is pushed toward and fixed on the end wall portion 56b so as to establish an electrical connection with the heater 26. A spring 64 in a contracted state is disposed between the casing 46 and the heater terminal 62. The spring 64 is made of conductive metal and has a spring constant smaller than that of the spring 54. The heater terminal 62 is pushed toward and fixed on the end wall portion 56b by the spring 64. The heater 26 is electrically connected to the heater terminal 62 via the spring 64 and the casing 46.
The cover 55 is protected by a synthetic resin protection cover 68 with an air space 70 kept therebetween. The protection cover 68 has a plurality of projections 69 on its inner surface so as to be in elastic contact with the lower edge of the cover 55. The cover 55 has, as integral members, a plurality of ribs 66 for maintaining an interval between the cover 55 and the protection cover 68. Further, the protection cover 68 has a plurality of projections 71 on its inner surface so as to maintain an interval between the cover 55 and the inner surface of the protection cover 68. [0033] '
The cover 55 includes a male coupler 65 extending outwardly from the tubular member 56. A pair of heater terminals 62, 63 confront the male coupler 65. A female

coupler 67 is detachably interlocked to the male coupler 65. A pair of cables 72 are used to electrically connect the heater terminals 62, 63 after the female coupler 67 is interlocked to the male coupler 65. The cables 72 pass through and are supported by a cable guide 73 formed on the outer surface of the protection cover 68 as an integral part. One of the cables 72 is connected to a charging/generating coil of an AC generator mounted on the motorcycle, while the other cable is grounded. Thus, when the engine is actuated, the PTC type heater 26 is electrically activated. As it is being heated, the heater 26 becomes more resistant. When the heater 26 has a high resistance value, an amount of current flowing thereto is regulated. [0034]
The operation of the first embodiment will be described hereinafter. During the initial operation of the engine, the wax 50 in the thermosensitive driver 25 expands in accordance with an ambient temperature. The piston 53 also projects from the casing 46 in accordance with the ambient temperature. Thus, the operating position of the throttle valve 23 also depends upon the ambient temperature. [0035]
When a main switch is operated so as to crank the engine, air is introduced into the engine via the starting air intake passage 15i in accordance with the operated position of the
throttle valve 23. Introduced air is mixed with fuel sucked in via the starting fuel nozzle 22, thereby producing an air-fuel mixture, which is supplied to the engine. [0036]
In response to the operation of the engine, the AC generator electrically actuates the heater 26. The wax 50 is heated by the heater 26, thus expanding, and causing the piston 53 to push the throttle valve 23 downward via the set collar 39 and the spring 37. The throttle valve 23 operates
to reduce the open area of the starting air intake passage 151 Finally, the starting air intake passage 15i is

completely closed, thereby interrupting the starting fuel.
[0037]
With this starting fuel regulator 21, the upstream and downstream opening amount adjusting regions 181, 191, which
are at the middle of the starting air intake passage 15\, are
formed in the carburetor body 10. The throttle valve 23 is slidably fitted in the hollow 20, in which both of the opening amount adjusting regions 18\ and 19\ confront. The
hollow 20 is formed in the carburetor body 10. The throttle
valve 23 directly controls the open areas of the opening amount adjusting regions 18\ and 19\. This throttle valve 23
is advantageous with respect to the reduced number of
components and the reduced number of assembly steps, compared
with a throttle valve which is slidably attached to a sleeve
forcibly inserted into the carburetor body 10. This is
because no sleeve is used for the throttle valve 23 in the
present invention. Further, when a sleeve is used, an area
between the carburetor body 10 and the sleeve for introducing air inevitably varies in the starting air intake passage 15because of sleeve manufacturing errors, and errors in assembling a sleeve in the starting air intake passage 15\.
Therefore, control of the amount and concentration of air-fuel mixture may be adversely affected by the varying area for introducing air. However, in the present invention, the
throttle valve 23 directly and precisely controls the open areas of the opening amount adjusting regions 18\ and 19with respect to the hollow 20. [0038]
The opening amount adjusting regions 18\ and 19\ have
cross sectional shapes defined by semi-circular upper
portions 18a and 19a and lower elongate oval portions 18b and
19b extending from the upper portions 18a and 19a along the
periphery of the hollow 20. Further, the bottom of the downstream opening amount adjusting region 19x is located a
height difference h lower than the bottom of the upstream opening amount adjusting region 18\. The opening amount

adjusting regions 181 and 191 are formed using cores (not shown) together with the circular hole 32 on the outer side
surface of the carburetor body 10, when the carburetor body 10 is cast. Thus, the opening amount adjusting regions 18i and 191 can be made without difficulty. Further, the opening amount adjusting regions 181, 191 and the circular hole 32 extend in parallel to the cast hole for the main air intake path 13, so that a casting device can be simplified, which is effective in improving the productivity and reducing manufacturing cost.
[0039]
The synthetic resin cover 55 having the tubular member 56 is detachably fixed on the retainer 43. The tubular member 56 includes the cylindrical portion 56a covering one end of the casing 46, and the end wall portion 56b which is thicker than the cylindrical portion 56a and functions as a heat accumulator. Thus, it is possible to enlarge a heat mass of the end wall portion 56b. This enables the wax 50 in the casing 46 to be kept hot. Further, it is possible to make the air space 70 as thin as possible between the cover 55 and the protection cover 68 in the outside of the cover 55. The starting fuel regulator 21 can be made compact. Temperature raising and lowering characteristics of the heater 26 can be moderated, which enables the wax 50 to be controlled in a wide temperature range.
[0040]
The foregoing structure can keep the wax 50 hot as
mentioned above, so that the thermosensitive driver 25 can be
made compact, and the starting fuel regulator 21 can be
further reduced in size. Referring to Fig. 7, a stroke of
the piston 53 is usually large in the related art
thermosensitive driver 25, as shown by a dashed line. It is
possible to shift an inflection point between a necessary
stroke and an ineffective stroke to a lower temperature side,
and to make the ineffective stroke smaller after the
inflection point. In the related art, when the starting fuel

regulator 21 is made compact, its heat mass is also downsized. Therefore, it has been very difficult to make the starting fuel regulator 21 smaller. However, in the present invention, since a heat maintaining capability of the wax 50 is improved because of an increased heat mass of the cover 55, the reduction of the heat mass of the thermosensitive driver 25 can be offset by minimizing the ineffective stroke of the piston as shown by a solid line in Fig. 7. The temperature raising and lowering characteristics of the thermosensitive driver 21 can be kept equal to those of the related art even when the starting fuel regulator 21 is made compact.
However, when the heat mass of the casing 46 in the thermosensitive driver 25 is reduced, it is necessary to prevent the throttle valve 23 from closing quickly as the heater 26 becomes hotter, compared with the related art throttle valve. This problem can be overcome by setting an internal resistance of the heater 26 larger than that of the related art heater, or by disposing a resistor between the heater 26 and the charging/generating coil. [0042]
The cover 55 includes, as an integral part, the coupler 65 facing the heater terminals 62 and 63. The coupler 67 is detachably interlocked with the coupler 65. Thus, the couplers 65 and 67 extensively increase the heat mass of the cover 55, so that the heated wax can be reliably kept hot. This structure facilitates the electrical connection to the heater 26, and maintenance of the starting fuel regulator.
Figs. 8 and 9 show a second embodiment of the present invention. Fig. 8 is a cross section of the carburetor body, and Fig. 9 is an enlarged section taken along line 9-9 in Fig. 8.
[0044]
A starting air intake path 152 includes: an upstream
path 16 which communicates with the upstream end of the main

air intake path 13, extends linearly from the main air intake
path 13 toward a downstream side, and has a circular cross
section; a downstream path 17 which communicates with the
downstream end of the main air intake path 13 and extends
linearly from the main air intake path 13 toward an upstream side; an upstream opening amount adjusting region I82
communicating with an upper end of the upstream path 16; and a downstream opening amount adjusting region 192
communicating with the a lower end of the downstream path 17. The upstream and downstream opening amount adjusting regions 182 and 192 are parallel to the main air intake path 13. A
throttle valve 23 (refer to Fig. 1) is fitted in a hollow 20 in the carburetor body 10. The upstream and downstream opening amount adjusting regions I82 and 192 open on an inner
surface of the hollow 20 so as to face each other via the hollow 20, and are spaced away from the main air intake passage 13 at their upstream and downstream ends respectively.
The upstream and downstream opening amount adjusting regions 182 and 192 have cross sectional shapes as shown in Fig. 9. The downstream opening amount adjusting region 192
has a diameter larger than that of the upstream opening amount adjusting region 182- Thus, the bottom of the downstream opening amount adjusting region 192 ^s lower by a
height difference h than the bottom of the upstream opening amount adjusting region 182. Inner diameters of the upstream
and downstream paths 16 and 17 are smaller than those of the upstream and downstream opening amount adjusting regions 182
and 192-
The upstream and downstream opening amount adjusting regions 182 and 192 are bored in the cast carburetor body 10
using a stepped drill (not shown), from the side of the downstream opening amount adjusting region 192• Tne outer end of the downstream opening amount adjusting region 192 ^s blocked by a ball 33 which is forcibly fitted therein.

[0047]
In the second embodiment of the invention, the throttle valve 23 directly controls the open areas of the upstream and downstream opening amount adjusting regions 182 and 192
facing the hollow 20. Thus, it is possible to reduce the number of components and the number of assembly steps, and to improve the control amounts because no sleeve is used in the present invention, as in the first embodiment.
The downstream opening amount adjusting region 192 ^s
first bored in the carburetor body 10, and the upstream opening amount adjusting region 182 is bored thereafter. The downstream opening amount adjusting region 192 is higher at
its bottom by the height difference h than the upstream opening amount adjusting region 192- The upstream and downstream opening amount adjusting regions I82 and 192 can
be easily made. As in the first embodiment, the downstream opening amount adjusting region 192 remains slightly open
even when the upstream opening amount adjusting region I82 is closed. This prevents a sudden fall of the air-to-fuel ratio. [0049]
The inner diameters of the upstream and downstream opening amount adjusting regions 182 and 192 are larger than
those of the upstream and downstream paths 16 and 17. This can relatively enlarge the open area of the starting air intake path 152 when the engine is started under a relatively
high ambient temperature. Thus, an amount of intake air in the starting air intake path 152 (shown by a dash-dot-dot
line in Fig. 4) can be substantially equal to the amount of intake air in the starting air intake path 151, which has the
special shape as shown in Fig. 3 related to the first embodiment, even when the ambient temperature is relatively high. This structure is effective in preventing the air-fuel mixture from becoming too rich, and improving the starting performance of the engine during hot weather. [0050]

Fig. 10 relates to a third embodiment of the invention.
Identical parts have identical reference numbers used in the
foregoing embodiments.
[0051]
A starting air intake path 153 includes: an upstream
path 16 which communicates with the upstream end of the main
air intake path 13, extends linearly from the main air intake
path 13 toward a downstream side, and has a circular cross
section; a downstream path 17 which communicates with the
downstream end of the main air intake path 13 and extends
linearly from the main air intake path 13 toward an upstream side; an upstream opening amount adjusting region I83
communicating with an upper end of the upstream path 16; and a downstream opening amount adjusting region 193
communicating with the lower end of the downstream path 17.
[0052}—
The downstream opening amount adjusting region 193 has a
diameter larger than that of the upstream opening amount adjusting region I83. The opening amount adjusting regions
183 and 193 are coaxial with the upstream path 16, and face
each other via the hollow 20. Inner diameters of the upstream and downstream opening amount adjusting regions I83
and 193 are larger than those of the upstream and downstream
paths 16 and 17. [0053]
The upstream and downstream opening amount adjusting regions 183 and 193 are bored in the cast carburetor body 10
using a three-tier drill (not shown), from a side of the downstream opening amount adjusting region 193. The outer end of the downstream opening amount adjusting region 192 ^s blocked by a ball 33 which is forcibly fitted therein.
The third embodiment is as advantageous as the second
embodiment. Further, since the upstream and downstream opening amount adjusting regions I83 and 193 and the upstream
path 16 are simultaneously formed, it is possible to reduce

the number of assembly steps. [0055]
The invention has been described with reference to the embodiment disclosed herein. It is not confined to the details set forth and this application is intended to cover all such modifications or changes as may come within the purposes of the improvements or the scope of the attached claims.
[Effect of the Invention]
According to the invention disclosed in claim 1, the carburetor body has an upstream opening amount adjusting region communicating with an upstream end of the main air intake path and constituting a part of the starting air intake path, a downstream opening amount adjusting region communicating with a downstream end of the main air intake path and constituting a part of the starting air intake path, and a hollow. The upstream and downstream opening amount adjusting regions confront each other via the hollow. The throttle valve is slidably fitted in the hollow and controls open areas of the upstream and downstream opening amount adjusting regions. A bottom of the downstream opening amount adjusting region is located a predetermined height difference lower than a bottom of the upstream opening amount adjusting region. Since no sleeve is used for the throttle valve, it is possible to reduce the number of components and the number of assembling steps. A maximum amount of intake air is regulated upstream of the throttle valve in order to increase negative pressure of the intake air around the throttle valve. Therefore, it is possible to prevent a sudden fall of the air-to-fuel ratio when the throttle valve is closed. This is effective in controlling the amount and concentration of the air-fuel mixture.
4-O0D7-K
According to the invention disclosed in claim 2, in addition to the configuration of the invention disclosed in

claim 1, when the carburetor body is cast, the upstream opening amount adjusting region and the downstream opening amount adjusting region are formed as cast holes by pulling cores in a direction from the upstream opening amount adjusting region to the downstream opening amount adjusting region, or after the carburetor body is cast, the upstream opening amount adjusting region and the downstream opening amount adjusting region are bored from a side of the downstream opening amount adjusting region. Therefore, the upstream and downstream opening amount adjusting regions can be formed without difficulty.
According to the invention disclosed in claim 3, in addition to the configuration of the invention disclosed in claim 2, the cores are pulled in the direction which is parallel to one of the directions in which a die for the carburetor body is pulled. A casting device can be simplified, which is effective in improving the productivity and reducing manufacturing cost. [0059]
According to the invention disclosed in claim 4, in addition to the configuration of the invention disclosed in claim 2, the starting air intake path comprises an upstream path having an upstream end communicating with the upstream end of the main air intake path, a downstream path having a downstream end communicating with the downstream end of the main air intake path, the upstream opening amount adjusting region communicating with the downstream end of the upstream path faces the hollow, and the downstream opening amount adjusting region communicating with the upstream end of the downstream path faces the hollow. Inner diameters of the upstream opening amount adjusting region and -the downstream opening amount adjusting region are larger than inner diameters of the upstream path and the downstream path. Therefore, these upstream and downstream opening amount adjusting regions having complicated shapes can be formed

easily, and are as effective as the upstream and downstream opening amount adjusting regions which are formed by making cast holes.
[Description of the Numerals]
10 carburetor body
13 main air intake path
151, 152, 153 starting air intake passages
16 upstream path
17 downstream path
181 182 183 upstream opening amount adjusting regions
191, 192 193 downstream opening amount adjusting regions
20 hollow
21 starting fuel regulator 23 throttle valve
25 thermosensitive driver

26 PTC type electric heater 46 casing 50 wax





WE CLAIM:
1. A starting fuel regulator for a carburetor, the starting fuel regulator comprising: a throttle valve (23) for controlling an open area of a starting air intake path (151, 152, 153) communicating with upstream and downstream ends of a main air intake path (13) formed in a carburetor body (10); thermosensitive driving means (25) for operating the throttle valve (23) in accordance with expansion or contraction of wax (50) with temperature variations, the wax (50) being housed in a casing (46) fitted in a carburetor body (10); and an electric heater (26) for heating the wax (50) and coupled to the casing (46),
characterized in that the carburetor body (10) has an upstream opening amount adjusting region (181, 182, 183) communicating with an upstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153), a downstream opening amount adjusting region (191, 192, 193) communicating with a downstream end of the main air intake path (13) and constituting a part of the starting air intake path (151, 152, 153) and a hollow (20), the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193) confronting each other via the hollow (20), the throttle valve (23) is slidably fitted in the hollow (20) and controls open areas of the upstream and downstream opening amount adjusting regions (181, 191; 182, 192; 183, 193), and a bottom of the downstream opening amount adjusting region (191, 192, 193) is located a predetermined height difference lower than a bottom of the upstream opening amount adjusting region (181, 182, 183).
2. The starting fuel regulator as claimed in claim 1, wherein the upstream opening amount adjusting region (181, 182, 183) and the downstream opening amount adjusting region (191, 192, 193) are formed as cast holes by pulling cores in a direction from the upstream opening amount adjusting region (181) to the downstream opening amount adjusting region (191), or the upstream opening amount adjusting region (181, 182, 183) and the

downstream opening amount adjusting region (191, 192, 193) are bored from a side of the downstream opening amount adjusting region (192, 193).
3. The starting fuel regulator as claimed in claim 2, wherein the starting air intake path (152, 153) comprises an upstream path (16) having an upstream end communicating with the upstream end of the main air intake path (13), a downstream path (17) having a downstream end communicating with the downstream end of the main air intake path (13), the upstream opening amount adjusting region (182, 183) communicating with the downstream end of the upstream path (16) faces the hollow (20), and the downstream opening amount adjusting region (192, 193) communicating with the upstream end of the downstream path (17) faces the hollow (20), and inner diameters of the upstream opening amount adjusting region (182, 183) and the downstream opening amount adjusting region (192, 193) are larger than inner diameters of the upstream path (16) and the downstream path (17).
4. A starting fuel regulator for a carburetor substantially hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

1690-DEL-1997-Abstract.pdf

1690-DEL-1997-Claims.pdf

1690-del-1997-complete specification (granted).pdf

1690-DEL-1997-Correspondence-Others.pdf

1690-DEL-1997-Correspondence-PO.pdf

1690-DEL-1997-Description (Complete).pdf

1690-DEL-1997-Drawings.pdf

1690-DEL-1997-Form-1.pdf

1690-DEL-1997-Form-13.pdf

1690-del-1997-form-19.pdf

1690-DEL-1997-Form-2.pdf

1690-DEL-1997-Form-3.pdf

1690-DEL-1997-Form-4.pdf

1690-DEL-1997-Form-6.pdf

1690-DEL-1997-GPA.pdf

1690-DEL-1997-Petition-137.pdf


Patent Number 242480
Indian Patent Application Number 1690/DEL/1997
PG Journal Number 36/2010
Publication Date 03-Sep-2010
Grant Date 27-Aug-2010
Date of Filing 23-Jun-1997
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA
Applicant Address 1-1, MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO, JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 MINORU UEDA, C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
2 SHUNJI AKAMATSU C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
3 MITSUO KATOH C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
4 MICHIO TAHATA C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
PCT International Classification Number F02M 1/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 HEI-8-187296 1996-07-17 Japan