Title of Invention

VEHICLE SPEED LIMITING SYSTEM

Abstract When a vehicle speed limit is made by thinning ignition, the quantity of unburned gas increases, CO and HCincrease, a load of a catalyst increases and the life of the catalyst is remarkably reduced. [Solving Means] A figure A shows a division of control, a first vehicle speed threshold and a second vehicle speed threshold which is higher speed than the first vehicle speed threshold are set, normal control is executed up to the first vehicle speed threshold, leaning control is executed between the first vehicle speed threshold and the second vehicle speed threshold, and leaning control and ignition control (the thinning of ignition) are executed above the second vehicle speed threshold. A figure B shows the opening /closing operation of a solenoid valve and a figure C shows ignition control, concretely whether ignition is thinned or not. [Effect] vehicle speed is gently lowered by leaning control at a first stage and is securely lowered by ignition control at a second stage. As combustation is continued under leaning control, the quantity of unburned gas is reduced and an emission level can be enhanced.
Full Text FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
COMPLETE SPECIFICATION
[See Section 10]
"VEHICLE SPEED LIMITING SYSTEM"



HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan
The following specification particularly describes the nature of the invention and the manner in which it is to be performed :-




GRANTED
19/6/2008

The present invention relates to a vehicle speed limiting system.
[Detailed Description of the Invention]
[0001]
[Technical Field of the Invention]
The present invention relates to a vehicle speed limiting system for limiting vehicle speed so that the vehicle speed does not exceed a vehicle speed threshold. [0002]

[Prior Art]
For vehicle speed limiting technique, Japanese published unexamined patent application No. HeilO-47143, "Internal combustion engine fuel limiting system" is proposed for example and is characterized in that as shown in Fig. 1 in the patent application, when the engine is abnormal, a solenoid valve 12 is controlled by a controller 10 so that the output of the engine is reduced little by little, fuel in a carburetor 3 is limited to prevent the overspeed of the engine and a catalyst is protected from heat. [0003] [Problems to be Solved by the Invention]
However, when fuel quantity is reduced by the system, the variation of fuel quantity delays, compared with the variation of air quantity because fuel is heavier than air. The reason is that the flowability pf fuel is inferior to that of air. [0004]
Therefore, the control of fuel by the solenoid valve has a limit, it is difficult to more smoothly limit the revolution of wheels, as the flowability of fuel is inferior to that of air when the failure of the engine is solved and normal operation is restored, smooth acceleration is delayed and running comfort is not acquired.
As the flowability of fuel is inferior to that of air, balance between fuel and air is not kept and as a result, unburned gas increases. As the unburned gas is burned in an exhaust emission control device, temperature in the exhaust


emission control device abnormally rises and the life of the
exhaust emission control device is reduced.
[0005]
Then, the object of the invention is to provide a vehicle speed limiting system that can solve the problems. [0006] [Means to Solve the Problems]
To achieve the object, Claim 1 is based upon a vehicle speed limiting system provided with a catalyst in an exhaust system for limiting vehicle speed by controlling ignition and is characterized in that a needle and a main air jet passage for mixing a part of air in fuel rising toward the needle beforehand are provided to a carburetor, a leaning mechanism composed of an air subpassage for adding air to the main air jet passage and a solenoid valve inserted into the air subpassage is provided and a controller that executes ignition control and leaning control according to a vehicle speed limit instruction is provided. [0007]
The yield of carbon monoxide (CO) gas and hydrocarbon (HC) is inhibited by leaning air-fuel mixture at the same time as ignition control, compared with a case that only ignition control is executed. If CO and HC are small, the quantity of combustion decreases and the life of a catalyst can be extended.
Under leaning control, the solenoid valve is opened and air flows into the main air jet passage via the air subpassage. Hereby, normally, subair in the air subpassage merges into main air flowing in the main air jet passage and air quantity

increases. As a result, air-fuel mixture is leaned. [0008]
To lean air-fuel mixture, it is required to reduce the quantity of fuel or to increase the quantity of air. When the quantity of fuel is reduced while the flow rate of air-fuel mixture is controlled by a throttle valve and leaning control is executed, the variation of fuel quantity delays, compared with the variation of air quantity because fuel is heavier than air. That is, the followability of fuel is inferior to that of air.
In that respect, as air quantity is increased in Claim 1, followability for the variation of a throttle angle is improved and transition from leaning control to normal control is smooth. [0009]
Further, in Claim 1, leaning is executed utilizing the main air jet passage . As air flowing in the main air j et passage is sucked according to negative pressure generated in the carburetor, air according to a throttle angle can be mixed in fuel beforehand without flow rate control by a flow rate control valve. Therefore, a low-priced solenoid valve that can be merely operated and closed has only to be inserted into the air subpassage, no complex control mechanism is required and the cost of the system can be reduced. [0010]
Claim 2 is characterized in that the controller starts leaning control when vehicle speed is a first vehicle speed threshold and starts ignition control when the vehicle speed


is a second vehicle speed threshold which is higher speed than the first vehicle speed threshold. [-0 011]
Vehicle speed is gently lowered by leaning control at a first stage and is securely lowered by ignition control at a second stage. Therefore, according to Claim 2, smooth vehicle speed limit control can be executed, compared with a case that leaning control and ignition control are simultaneously executed. [0012] [Mode for carrying out the Invention]
Referring to attached drawings, an embodiment of the invention will be described below. The drawings shall be viewed in a direction of a reference number.

[Brief Description of the Drawings] [Fig. 1]
Fig. 1 shows the principle of a vehicle speed control system according to the invention; [Fig. 2]
Fig. 2 shows the principle of a carburetor according to the invention; [Fig. 3]
Figs. 3 are explanatory drawings for explaining the action of a leaning mechanism according to the invention; [Fig. 4]
Figs. 4 are a first time chart of a vehicle speed limiting system according to the invention; [Fig. 5]
Fig. 5 shows an output curve corresponding to Figs. 4; [Fig. 6]
Figs. 6 are a second time chart of the vehicle speed limiting system according to the invention; [Fig. 7]
Fig. 7 shows an output curve corresponding to Figs. 6; and [Fig. 8]
Figs. 8 are a third time chart of the vehicle speed limiting system according to the invention.


Fig. 1 shows a principle of a vehicle speed control system according to the invention. The vehicle speed control system 10 is composed of an air cleaner 11, an internal combustion engine for combusting air- fuel mixture supplied by a carburetor 30 and an air intake system 13 in an engine 14 and exhausting via an exhaust system 16 provided with a catalytic converter 15, air subpassages 17 and 18 branching from the air cleaner 11, a solenoid valve 19 inserted between these passages and a controller 22 for receiving vehicle speed information detected by a vehicle speed sensor 21, determining whether vehicle speed is to be limited or not and controlling ignition and the operation of the solenoid valve 19. [0013]
Fig. 2 shows a principle of the carburetor according to

the invention. The carburetor 30 is a negative pressure operated carburetor provided with a leaning mechanism having structure that a porous tube 34 called a needle jet and a venturi piston 35 are attached to a valve body 33 provided with a throttle valve 32 at the exit of a venturi part 31, an upper part of the venturi piston 35 is hung by a diaphragm 36, a needle 37 is attached at the bottom of the venturi piston 35, the needle 37 is inserted into the porous tube 34, a main air jet passage 3 9 is made in a toroidal air chamber 3 8 surrounding the porous tube 34 from an entrance of the venturi part 31 and the air subpassage 18 is merged into the main air jet passage 39. [0014]
A reference number 40A denotes an air jet provided to the main air passage 39 (a main air jet for the main air passage) , 40B denotes an air jet provided to the air subpassage 18 (a main air jet for the air subpassage) as shown in an enlarged view and both are a throttling element for precisely regulating the flow rate of air. [0015]
To explain the operation of the carburetor 30, when the throttle valve 32 is opened, air quantity from the air cleaner 11 toward the air intake system 13 increases and pressure in the vicinity of the venturi piston 35 is reduced more. That is, large negative pressure is caused. In the meantime, upstream side (entrance side) air pressure acts on the lower surface of the diaphragm 36 and the negative pressure acts on the upper surface of the diaphragm 36 via a suction hole 41. The larger differential pressure between the upper and low

surfaces of the diaphragm 36 is, the more the venturi piston 35 rises against a spring 42 and the needle 37 also rises. As the needle 37 is tapered, clearance with the porous tube 34 increases as the needle is lifted. [0016]
Fuel 44 passes a throttle nozzle called a main jet 45 and enters the venturi part 31 through between the porous tube 34 and the needle 37. At that time, as air is blown from the toroidal air chamber 38, the air is mixed in fuel. [0017]
For a method of supplying air to the toroidal air chamber 38, there are the following methods (1) and (2).
(1) A part of air at the entrance of the venturi part 31 is supplied to the toroidal air chamber 38 via only the main air jet passage 39 without being supplied from the air subpassage 18.
(2) Subair is added to main air flowing in the main air jet passage 39 from the air subpassages 17 and 18 and increased air is supplied to the toroidal air chamber 38.
The action of the solenoid valve for realizing the methods (1) and (2) will be described referring to the following drawing. [0018]
Figs. 3A and 3B are explanatory drawings for explaining the action of the leaning mechanism according to the invention.
A leaning mechanism 46 is composed of the air subpassages 17 and 18 for adding air to the main air jet passage and the solenoid valve 19 inserted between the air subpassages 17 and


18.
In Fig. 3A, as the solenoid valve 19 is closed, a part of air in the air cleaner 11 reaches the primary side of the solenoid valve 19 as shown by an arrow, however, the air does not reach the air subpassage 18 . That is, the leaning mechanism becomes the state described in (1).
In Fig. 3B, as the solenoid valve 19 is opened, a part of air in the air cleaner 11 flows in the air subpassage 17 and in the air subpassage 18 and reaches the carburetor 30. That is, the leaning mechanism becomes the state described in (2) . [0019]
Figs. 4A to 4C are a first time chart of the vehicle speed limiting system according to the invention and all the x-axes show vehicle speed.
Fig. 4A shows a division of control, vehicle speed to be limited is called a vehicle speed threshold, vehicle speed limit control according to the invention is executed above the vehicle speed threshold and normal control remains below the vehicle speed threshold.
Fig. 4B shows the opening/closing operation of the solenoid valve, the solenoid valve is closed up to the vehicle speed threshold and is opened above the vehicle speed threshold. As described above, when the solenoid valve is opened, air-fuel mixture is leaned.
Fig. 4C shows ignition control, concretely whether ignition is thinned or not, normal ignition is executed up to the vehicle speed threshold and ignition is thinned above the


vehicle speed threshold. As ignition is not made every time when ignition is thinned, the output of the engine is rapidly reduced. [0020]
Fig. 5 shows an output curve corresponding to Figs. 4, the x-axis shows vehicle speed and the y-axis shows the output of the engine.
As leaning control and the thinning of ignition are executed above the vehicle speed threshold, the output is rapidly reduced. Vehicle speed rapidly lowers by the reduction of the output. When vehicle speed is below the threshold, normal control is restarted. [0021]
Figs. 6A to 6C are a second time chart of the vehicle speed limiting system according to the invention and all the x-axes show vehicle speed.
Fig. 6A shows a division of control, a first vehicle speed threshold and a second vehicle speed threshold which is higher speed than the first vehicle speed threshold are set, normal control is executed up to the first vehicle speed threshold, leaning control is executed between the first vehicle speed threshold and the second vehicle speed threshold, and leaning control and ignition control (the thinning of ignition) are executed above the second vehicle speed threshold.
Fig. 6B shows the opening/closing operation of the solenoid valve, the solenoid valve is closed up to the first vehicle speed threshold and is opened above the first vehicle speed threshold.

Fig. 6C shows ignition control, concretely whether ignition is thinned or not, normal ignition is executed up to the second vehicle speed threshold and ignition is thinned above the second vehicle speed threshold. As ignition is not made every time when ignition is thinned, the output of the engine is rapidly reduced. [0022]
Fig. 7 is an output curve corresponding to Figs. 6 and the y-axis shows the output of the engine.
First, leaning control is executed above the first vehicle speed threshold. As ignition is continued though air-fuel mixture is leaned, fuel is used in the engine in succession. As a result, the output of the engine is reduced by approximately 20%. When vehicle speed nevertheless increases and exceeds the second vehicle speed threshold, leaning control and the thinning of ignition are executed. As a result, the output of the engine is rapidly reduced and vehicle speed rapidly lowers by the reduction of the output. When vehicle speed becomes below the vehicle speed threshold, normal control is restarted. [0023]
When Fig. 7 is compared with Fig. 5, in Fig. 7, vehicle speed is gently lowered by leaning control at a first stage and is securely lowered by ignition control at a second stage. Therefore, compared with Fig. 5 (leaning control and ignition control are simultaneously executed), smooth vehicle speed limit control can be executed.
In addition, as combustion is continued during leaning

control, unburned gas is hardly caused, a load in a catalyst is reduced and an emission level can be kept a high level. [0024]
Figs. 8A to 8C are a third time chart of the vehicle speed limiting system according to the invention and all the x-axes show vehicle speed.
Fig. 8A shows a division of control, a first vehicle speed threshold and a second vehicle speed threshold which is higher speed are set, normal control is executed up to the first vehicle speed threshold, normal control or leaning control is selectively executed between the first vehicle speed threshold and the second vehicle speed threshold, and leaning control and ignition control (the thinning of ignition) are executed above the second vehicle speed threshold. [0025]
Fig. 8B shows the opening/closing operation of the solenoid valve, when vehicle speed increases, the solenoid valve is closed up to the second vehicle speed threshold and is opened above the second vehicle speed threshold. Conversely, when vehicle speed decreases, the solenoid valve is opened up to the first vehicle speed threshold and is closed below the first vehicle speed threshold.
Fig. 8C shows ignition control, concretely whether ignition is thinned or not, normal ignition is executed up to the second vehicle speed threshold and ignition is thinned above the second vehicle speed threshold. As ignition is not made every time when ignition is thinned, the output of the engine is rapidly reduced.

[0026]
The following effect can be expected by using different thresholds for acceleration and deceleration in Fig. 8B.
It is supposed that vehicle speed temporarily remains in the vicinity of the second vehicle speed threshold in Fig. 8B. That is, when vehicle speed exceeds the second vehicle speed threshold, the vehicle speed is lowered to execute leaning control and ignition control. However, in case vehicle speed immediately increases in leaning control to be executed when the vehicle speed is below the second vehicle speed threshold, a chattering phenomenon that the opening and the closing of the solenoid valve are frequently repeated based upon the second vehicle speed threshold is caused. When the chattering phenomenon is caused, vehicle speed becomes unstable, running comfort is deteriorated and the life of the solenoid valve is largely deteriorated. [0027]
The frequency of the opening/closing of the solenoid valve can be reduced by providing hysteresis as shown in Fig. 8B when there is such fear, the chattering phenomenon can be prevented from being caused, running comfort becomes satisfactory and the life of the solenoid valve can be extended. [0028]
The vehicle speed control system according to the invention can be applied to any of a motorcycle, a three-wheeled vehicle and a four-wheel vehicle, however, as the vehicle speed control system according to the invention is completed by only providing the thin air subpassage between the existing air


cleaner and the carburetor and inserting the solenoid valve into the air subpassage, small space has only to be secured. Therefore, the vehicle speed control system according to the invention is effective when it is applied to a motorcycle having remarkable constraint in space for housing equipment. [0029]
As the leaning mechanism described in Claim 1 can be also realized by linking the air subpassage to the exist of the venturi part of the carburetor in addition to the mechanism shown in Fig. 3A, the structure of the mechanism is not limited to the embodiment. [0030] [Effect of the Invention]
The invention produces the following effect owing to the configuration described above.
The vehicle speed limiting system according to Claim 1 is characterized in that the leaning mechanism for leaning air-fuel mixture is provided to the carburetor and the controller for executing ignition control and leaning control according to a vehicle speed limiting instruction is provided, and the yield of CO gas and HC is inhibited by leaning air-fuel mixture at the same time as ignition control, compared with a case that only ignition control is executed. When CO and HC are small, the quantity of combustion is reduced and the life of the catalyst can be extended. [0031]
That is, Claim 1 is characterized in that the carburetor is provided with the needle and the main air jet passage for


mixing a part of air in fuel rising toward the needle beforehand and the leaning mechanism is composed of the air subpassage for adding air to the main air jet passage and the solenoid valve inserted into the air subpassage, as leaning is realized by increasing air quantity, the variation of a throttle angle is followable and particularly, transition from leaning control to normal control is smooth. [0032]
Further, according to Claim 1, leaning is executed utilizing the main air jet passage. As air flowing in the main air jet passage is sucked according to negative pressure generated in the carburetor, air according to a throttle angle can be mixed with fuel beforehand without controlling a flow rate by a flow rate control valve. Therefore, the low-priced solenoid valve in which only opening/closing operation is enabled has only to be inserted into the air subpassage and no complex control mechanism is required. [0033]
Claim 2 is characterized in that the controller starts leaning control when vehicle speed is the first vehicle speed threshold and starts ignition control when the vehicle speed is the second vehicle speed threshold which is higher speed than the first vehicle speed threshold, the vehicle speed is gently lowered by leaning control at the first stage and is securely lowered by ignition control at the second stage. Therefore, according to Claim 2, smooth vehicle speed limit control can be executed, compared with a case that leaning control and ignition control are simultaneously executed.



[Description of Reference Numbers]
10 Vehicle speed limiting system, 14 Engine, 15
Catalytic converter, 16 Exhaust system, 17, 18 Air
subpassage, 19 --- Solenoid valve, 21 --- Vehicle speed sensor,
22 --- Controller, 30 --- Carburetor, 37 --- Needle, 39 ---Main air jet passage, 40A, 40B --- Air jet, 46 --- Leaning mechanism

We claim:
1. A vehicle speed limiting system (10) provided with catalyst in an exhaust system (16) for limiting vehicle speed by controlling ignition, characterized in that:
a needle (37) and a main air jet passage (39) for mixing a part of air in fuel rising toward the needle (37) beforehand are provided to a carburetor (30);
a leaning mechanism composed an air subpassage (17) for adding air"to the main air jet passage (39) and a solenoid valve (19) inserted into the air subpassage (17) is provided; and
a controller (22) that executes ignition control and leaning control according to a vehicle speed limit instruction is provided.
2. A vehicle speed limiting system (10) as claimed in claim 1, wherein;
the controller (22) starts leaning control when vehicle speed is a first vehicle speed threshold and starts ignition control when the vehicle speed is a second vehicle speed threshold which is higher speed than the first vehicle speed threshold.
3. A vehicle speed limiting system (1) substantially as hereinbefore
described with reference to the accompanying drawings.
Dated this 06.01.2003
[VINEET ROHlLLA]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT]

Documents:

9-mum-2003-abstract(19-6-2008).doc

9-mum-2003-abstract(19-6-2008).pdf

9-mum-2003-cancelled pages(19-6-2008).pdf

9-mum-2003-claims(granted)-(19-6-2008).doc

9-mum-2003-claims(granted)-(19-6-2008).pdf

9-mum-2003-correspondence(19-6-2008).pdf

9-mum-2003-correspondence(ipo)-(11-7-2008).pdf

9-mum-2003-drawing(19-6-2008).pdf

9-mum-2003-form 1(19-6-2008).pdf

9-mum-2003-form 1(6-1-2003).pdf

9-mum-2003-form 13(19-6-2008).pdf

9-mum-2003-form 18(5-12-2006).pdf

9-mum-2003-form 2(granted)-(19-6-2008).doc

9-mum-2003-form 2(granted)-(19-6-2008).pdf

9-mum-2003-form 3(6-1-2003).pdf

9-mum-2003-form 3(6-4-2004).pdf

9-mum-2003-form 5(6-1-2003).pdf

9-mum-2003-power of authority(19-6-2008).pdf

9-mum-2003-power of authority(28-3-2003).pdf

abstract1.jpg


Patent Number 221949
Indian Patent Application Number 9/MUM/2003
PG Journal Number 39/2008
Publication Date 26-Sep-2008
Grant Date 11-Jul-2008
Date of Filing 06-Jan-2003
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 MASANOBU MATSUZAKI C/O. KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1 CHUO 1-CHOME, WAKO-SHI, SAITMA, JAPAN
2 SHOSUKE SUZUKI C/O Kabushiki Kaisha Honda Gijutsu Kenkyusho, 4-1,Chuo 1-chome, Wako-shi, Saitama
3 HIROFUMI WAKAYAMA C/O Kabushiki Kaisha Honda Gijutsu Kenkyusho, 4-1,Chuo 1-chome, Wako-shi, Saitama
4 ATSUSHI KATAYAMA C/O Kabushiki Kaisha Honda Gijutsu Kenkyusho, 4-1,Chuo 1-chome, Wako-shi, Saitama
PCT International Classification Number B60K31/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2002-004949 2002-01-11 Japan