Title of Invention

AN AUTO CHOKE CONTROL DEVICE

Abstract An auto choke control device, equipped with a battery power-supplied auto choke for providing heat causing thermowax to expand and drive a sliding throttle value for opening and closing a fuel path for starting a carburetor, for opening the passage of current from a battery to the auto choke heater, comprising pulse control means for controlling a pulse so as to control the time that current is supplied to the auto chock heater when engine speed is equal to greater than a set speed; Where the said pulse control means comprises a transistor for interrupting current from the battery to the auto choke heater and a microcomputer for applying a pulse width modulated on pulse to a base of the transistor; Characterized in that the said miscompute adjusts the width of the on-pulse according to detected temperature from a temperature detecting sensor detecting temperature of an engine and varies the width of the on-pulse so that when the detecdted temperature is high, the width of the on-pulse to the base of the transistor is made wider, and when the detected temperature is low, the width of the on-pulse to the base of the transistor is made narrower.
Full Text FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See Section 10; rule 13]
"AN AUTO CHOKE CONTROL DEVICE"
HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan having a place of business at 1-1, Minamiaoyama 2-Chome, Minato-ku, Tokyo, JAPAN
The following specification particularly describes the invention and the manner in which it is to be performed:

The present invention relates to an auto choke control device.
This present invention relates to an auto choke control device, and more particularly to an auto choke control device for facilitating change of the time current is supplied to the auto choke heater. 10002] [Related Art]
A vehicle carburetor can be provided with an auto choke so that smooth ."■tariing-up or warming-up of the engine is automatically obtained according to external temperature or a warmed-up condition of an engioi.i,.,An auto choke can have an ¥uto choke heater and be integrally provided with a carburetor. {0003]
An auto choke provided with an auto choke heater applies a portion of a voltage generated by a flywheel magneto to the auto choke heater and heats a ceramic plate. Further, the heat of the ceramic board expands therraowax and activates a

starter plunger to adjust supplied fuel amount.
[0004]
As an example of such an auto choke control device, Japanese Patent Laid-open Publication No. He:^8-42398 discloses adjusting voltage to an auto choke heater by varying a resistance value of a voltage adjustment resistor, being an external resistor.
10005]
Namely, as shown in Fig. 8, one end of an auto choke heater 1 is connected to a control transistor 3 through a voltage adjustment resistor 2. The auto choke heater 1 expands with heating of thermowax to close a starter plunger (not shown). Additionally, the voltage adjustment resistor 2 has a certain resistance value so as to adjust a voltage to the auto choke heater 1.
Further, the other end of the auto choke heater 1 is connected to the three-phase magneto 4 through a regulator 7. A battery 9 is provided between the auto choke heater 1 and a lamp switch 8 for turning on a lamp
[0008]
With such a structure, when engine speed is input to the control transistor 3 upon starting an engine, voltage is applied to the auto choke heater 1 activated by the control transistor 3. In this case, since the voltage adjustment resistor 2 adjusts to lower the voltage applied to the auto choke heater 1, expansion of the thermowax (not shown) becomes gentle. As a result, the starter plunger (not shown) closes gently, avoiding sudden change of supplied fuel amount, thus preventing an engine from being stalled.
[0009] [Problems to be Solved by the Invention]
However, with the auto choke control device of the above related art, voltage to the auto choke heater 1 is adjusted by the voltage adjustment resistor 2, being
an external resistor. In this case, because the resistance value of the voltage
. .. -
adjustment resistor 2 is necessary to set a resistance value suitable

characteristics are used, voltage must be adjusted by switching the voltage adjustment resistor 2. Therefore, a method of switching such a voltage adjustment resistor 2 causes increased costs.. [0010]
In addition, if voltage to the auto chok-e heater I is merely adjusted by the voltage adjustment resistor 2, since the voltage adjustment resistor 2 has a constant resistance value, the auto^hokeJ,S-.noi^[email protected],Q--~-e^
temperature. Thus when a fuel mixture temporarily becomes rich, unnecessary fuel is | e^^* wasteSr or on the other hand, when the fuel mixture becomes weak, it may take time to warm up, eventually deteriorating accuracy of controlling an auto choke.
[OOll] The present invention has been conceived in view of the above described situation, and an object of the present invention is to provide an auto choke control device for improving accuracy of controlling an auto choke without having increased costs.
According to the present invention there is provided an auto choke control device, equipped with a battery power-supplied auto choke heater for providing heat causing thermowax to expand and drive a sliding throttle valve for opening and closing a fuel path for starting a carburetor, for controlling the passage of current from a battery to the auto choke heater, comprising pulse control means for controlling a pulse so as to control the time that current is supplied to the auto choke heater when engine speed is equal to or greater than a set engine speed;
wherein the said pulse control means comprises a transistor for interrupting current from the battery to the auto choke heater and a microcomputer for applying a pulse width modulated on pulse to a base of the transistor;
characterized in that the said microcomputer adjusts the width of the on-pulse according to detected temperature from a temperature detecting sensor detecting temperature of an engine, and varies the width of the on-pulse so that when the detected temperature is high, the width of the on-pulse to the base of the transistor is made wider, and when the detected temperature is low, the width of the on-pulse to the base of the transistor is made narrower.
In an auto choke control device relating to the present invention, without using external resistance for adjusting voltage to an auto choke heater, by using pulse control means, a pulse is controlled so as to control the time current is supplied to the auto choke heater when engine speed is equal to or greater than a set speed, and the width of an on-pulse is varied according to a detected temperature.

In the invention of the document US 4,730,589, the circuit controls the auto choke at three stages. At first stage, the current is cutoff, at second stage, a rated current is provided and at the third stage, current is reduced by half by producing current from an oscillator with 50% duty cycle.
The aforementioned document pertains to the degree of opening or closing of the choke valve with respect to time i.e. it depicts the rate of opening and closing of the choke.
The present invention controls the duration for which a choke valve remains open or close depending on the temperature as shown in figure 7. The pulse width can be varied depending on the temperature for which the choke valve remains open or close.
[BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS]
Fig. 1 is an equivalent circuit diagram showing an embodiment of an auto choke control device relating to the present invention.
Fig. 2 is a diagram describing movement of the auto choke control device in Fig. 1.
Fig. 3 is a drawing showing an example of a motor cycle engine to which the auto choke control device in Fig. 1 is applied.
Fig. 4 is a cross sectional view showing the auto choke in Fig. 3.
Fig. 5 is a cross sectional view along line a-a showing the auto choke in Fig. 4.
Fig. 5 is a cross sectional view showing a concrete structure of the auto choke in Fig. 4.
Fig. 7 is a diagram showing another embodiment of the auto choke control device in Fig. 1.
Fig. 8 is an equivalent circuit diagram showing an example of the auto choke control device of the related art.

[0013]
[Embodiments] Embodiments of the present invention will now be described in the following.
[0014]
Fig . I is an equivalent circuit diagram showing an embodiment of an auto choke control device relating to the present invention. Fig. 2 is a diagram describing movement of the auto choke control device in Fig. 1, Fig. 3 is a drawing showing an example of a motor cycle engine to which the auto choke control device in Fig. 1 is applied, and Fig. 4 to Fig. 6 are drawings of the auto choke mounted on the carburetor in Fig. 3.
[0015]
First, an engine to which the auto choke control device in Fig. 1 is applied will be described using Fig. 3 to Fig 6.
[0016]
A piston 12 linked to a connecting rod II is provided inside a cylinder block 10 of an engine in Fig. 3. A cylinder head 15 forming a combustion chamber together with the piston 12 is provided at an upper part of the cylinder block 10.
[0017]
An intake valve 18 and an exhaust valve 19 opened and closed by a camshaft 16 and rocker arms 17 are provided in the cylinder block 15. Also, an intake manifold 20 is linked to the cylinder head 15. In addition, a carburetor 21 producing a fuel mixture to be supplied to the inside of the combustion chamber is provided in the intake manifold 20.
[0018]
On the other hand, the carburetor 21 is provided with, for example, an auto choke 22 as shown in Fig. 4. A starting fuel adjustment device A and a thermo-drive device B are provided in the auto choke 22 shown in Fig. 4, and a starting air passage 28 and a starting fuel mixture passage 29 are provided in the starting fuel adjustment device A.
[0019]
Additionally, the starting air passage 28, shown in Fig. 5 for example, communicates with part of a main air supply passage 27 upstream from a throttle valve 26, and the starting fuel mixture passage 29 communicates with part of the main air supply passage 27 downstream from the throttle valve 26. Further, a sliding throttle valve 31 of the starting fuel adjustment device A is installed between the starting air passage 28 and the starting fuel mixture passage 29, and the sliding throttle
-6

valve 31 communicates with a float chamber 24. [0020]
A concrete structure of the starting fuel adjustment device A and the thermo-drive device B of the auto choke 22 in Fig. 4 is described in Fig. 6. Namely, the starting fuel adjustment device A is provided with a main body of the carburetor 23 and the thermo-drive device B is provided on the upper part of the starting fuel adjustment device A. [0021]
A starter well 25 communicating with the float chamber 24 is provided in the lower part of the main body of the carburetor 23. Also, the starting fuel mixture passage 29 is placed inside the main body of the carburetor 23. [0022]
A measuring needle valve 33 inserted into a starting fuel nozzle 32 is attached to the sliding throttle valve 31 of the starting fuel adjustment device A. The sliding throttle valve 31 is forced down by a spring 35 disposed between a set collar 34 at the thermo-drive device B side. [0023]
A case 38 storing a piston 36 and pliable material 37, such as rubber or silicone, is fitted into the set collar 34. A capped case 40 storing thermowax 39 is attached to the case 38. -The flow material 37 and the thermowax 39 are isolated by a diaphragm 41. [0024]
A PTC type auto choke heater 42 of an auto choke control device for expanding the thermowax 39 by heat is attached on the top of the capped case 40. Power is supplied to the PTC type heater 24 through a female coupler 45 connected to terminals 43 and 44. [0025]
In other words, the auto choke control device is equipped with the PTC type heater 42, a ECU 48 having a microcomputer 46 and a transistor 47, a speed detecting sensor 49, and a temperature detecting sensor 50, shown in the equivalent circuit diagram of Fig. I.Here, a pulse control means is constituted by the microcomputer 46 and the transistor 47. [0026]
The speed detecting sensor 49 supplies ACG produced when an engine is rotated, or a detection signal from a crank pulsar or the like, to the ECU48. The temperature detecting sensor 50 detects temperature of the engine (temperature in a cooling water

jacket) and supplies the detected signal to the ECU 48. [0027]
One end of the PTC type heater is connected to a power supply 1 ine 51 connected to a battery (not shown). The other side of the PTC type heater is connected to the connector side of the transistor 47. An on-pulse that is with PW\ (pulse width modulation) controlled by the microcomputer 46 is applied to the base of the transistor 47. [0028]
The microcomputer 46 applies on-pulse 51a having a PWM (pulse width modulated) width to the base of the transistor 47 to turn the transistor 47 on, for example, when engine speed obtained by the speed detecting sensor 49 is equal to or greater than a set speed. [0029]
Namely, such a PWM (pulse width modulation) control is operated by a program programmed in advance according to characteristics of the engine. As a result, characteristics of the engine during warm-up exhibit the same characteristics if engines are the same type. [0030]
Next, operation of the auto choke control device in such a structure will be described. [0031]
First of all, when an engine starts, the thermowax 39 shown in Fig. 6 is in an expanding condition corresponding to atmospheric temperature, and an extent of protrusion from the case 38 of the piston 36 also corresponds to the atmospheric temperature. In this way, operational position of the sliding throttle valve 31 also corresponds to the atmospheric temperature. [0032]
In this condition, when a main switch (not shown) is turned on and rotated to the starter position for starting the engine, fuel mixture concentration supplied to the engine through the starting air passage 28 and the starting fuel mixture passage 29 as starting fuel passageways becomes rich, and so the engine starts easily at a cold temperature. [0033]
When the engine starts, the engine speed is detected by the speed detecting sensor 49, and if the engine speed is equal to or greater than a set speed, the microcomputer 46 shown in Fig. 1 drives the transistor 47 using PWM (pulse width

modulation) control. As a result, the transistor 47 is turned on, and current from the power supply line 51 is supplied to the PTC type heater 42. [0034]
In this case, the thermowax 39 shown in Fig. 6 gradually expands in volume due to heat from the PTC type heater 42, pushing down the sliding throttle valve 31, thus gradually closing the starting fuel nozzle 32 with the measuring needle valve 33. Also, around the time the engine warm-up operation is finished, the starting fuel nozzle 32 is completely closed. As a result, fuel amount supplied to the engine through the starting air passage 28 and the starting fuel mixture passage 29 as starting fuel passageways decreases as the warm-up condition progresses, and eventually matches with a required fuel mixture concentration. ■ [0035]
Incidentally, when engine temperature (temperature in a cooling water jacket) increases during engine warm-up, the temperature is detected by the temperature detecting sensor 50. Because of this, even if the engine is stopped during warm-up, the microcomputer 46 keeps driving the transistor 47 under PWM (pulse width modulation) control unti 1 the engine temperature is equal to or lower than a set vajue. [0036]
After the engine is stopped, if it is re-started while the engine temperature is still high, fuel through the starting air passage 28 and the starting fuel mixture passage 29 as starting fuel passageways is not supplied, and fuel mixture concentration to the engine is the same as in a normal operation, thus matching with the required fuel mixture concentration. [0037]
In addition, when the engine temperature reaches equal to or lower than a set value after the engine is stopped, the thermowax 39 gradually contracts and the lock of the starting fuel nozzle 32 by the measuring needle valve 33 is gradually released. Therefore, when the engine is re-started after a considerable time has passed, fuel mixture concentration becomes rich, similar to the situation described above when starting at the atmospheric temperature. [0038]
Therefore, in this embodiment, v
Also, when such an auto choke is applied to engines with different characteristics, changing the on-pulse width for the microcomputer 46 according to the corresponding characteristics of engines makes it easy to handle the difference, therefore avoiding increased costs. [0039]
Furthermore, the auto choke control by PWM (pulse width modulation) control of the transistor 47 can cause less fluctuation of operating time for the auto choke, compared to the related art voltage adjustment using an external 2-esistor. This is because the fluctuation in PWM (pulse width modulation) control of the transistor 47 is small compared to fluctuation of a resistance value of the external resistor of the related art. [0040]
Incidentally, in this embodiment it is described that when engine speed is equal to or greater than a set speed, the time that current is supplied to the PTC type heater 42 is controlled by pulse control of the transistor 47, but the present invention is not limited to this example, and it is also possible to perform PWM (pulse width modulation) control of the transistor 47 by linking to a detected signal from the temperature detecting sensor 50 for detecting an engine temperature. [0041]
In this case, for example as shown in Fig. 7, the microcomputer 46 should have a map indicating the relationship between the detected temperature and the width of an on-pulse 51a to the base of the transistor 47. Then, when the temperature detected by the temperature detecting sensor 50 is high, time for controlling the auto choke can be shortened by widening the width of the on-pulse 51a to the base of the transistor 47. [0042]
In addition, when the temperature detected by the temperature detecting sensor 50 is low, time for controlling the auto choke can be lengthened by narrowing the width of the on-pulse 51a to the base of the transistor 47. By doing this, the fuel mixture no longer becomes temporarily too rich and so fuel is not wasted, and nor does the fuel mixture become too weak so that it takes a long time to warm up, making it possible to improve the accuracy of controlling an auto choke. [0043]
In addition, when the engine temperature is to be detected, it is also possible to use means for directly detecting temperature of a main body of an engine, such as a cylinder block or a cylinder head, or means for detecting temperature of

cooling water of a water cooled engine. Also, as for the transistor 47, by using a FET (field effect transistor), output of an auto choke control device is increased, thus enabling improved flexibility. [0044] [Effects of the Invention]
The auto choke control device to which the present invention relates performs pulse control, without using an external resistor for adjusting voltage to an auto choke heater, using pulse control means, so as to control the time that current is supplied to the auto choke heater when engine speed is equal to or greater than a set speed, as well as adjusting the width of the on-pulse according to detected temperature, therefore improving the accuracy of controlling an auto choke without increased costs.


[Description of the numerals]
1 Auto choke heater
2 Voltage adjustment resistor

4 Three-phase magneto 4a Ignition coil
5 Condenser discharge igniter (CDI)
6 Spark plug
7 Regulator


8 Lamp switch 8a Lamp
9 Battery

10 Cylinder block
11 Connecting rod
12 Piston

15 Cylinder head
16 Camshaft
17 Rocker arm
18 Intake valve
19 Exhaust valve
20 Intake manifold
21 Carburetor
22 Auto choke
23 Main body of carburetor
24 Float chamber
25 Starter well
26 Throttle valve
27 Main air supply passage
28 Starting air passage
28 Starting fuel mixture passage
31 Sliding throttle valve
32 Starting fuel nozzle
33 Measuring needle valve
34 Set collar
35 Spring
36 Piston
37 Pliable material
38 Case
39 Thermowax
40 Capped case
41 Diaphragm
42 PTC type heater
43 Terminal
44 Terminal
45 Coupler

46 Microcomputer
47 Transistor 48. ECU

49 Speed detecting sensor
50 Temperature detecting sensor
51 Power supply line 51a On-pulse
A Starting fuel adjustment device B Thermo-drive device


WE CLAIM;
1. An auto choke control device, equipped with a battery power-supplied auto choke heater for providing heat causing thermowax to expand and drive a sliding throttle valve for opening and closing a fuel path for starting a carburetor, for controlling the passage of current from a battery to the auto choke heater, comprising pulse control means for controlling a pulse so as to control the time that current is supplied to the auto choke heater when engine speed is equal to or greater than a set engine speed;
wherein the said pulse control means comprises a transistor for interrupting current from the battery to the auto choke heater and a microcom.puter for applying a pulse width modulated on pulse to a base of the transistor;
characterized in that the said microcomputer adjusts the width of the on-pulse according to detected temperature from a temperature detecting sensor detecting temperature of an engine, and varies the width of the on-pulse so that when the detected temperature is high, the width of the on-pulse to the base of the transistor is made wider, and when the detected temperature is low, the width of the on-pulse to the base of the transistor is made narrower.
2. An auto choke control device substantially as herein described with reference to the accompanying drawings.

Documents:

232-mum-2001-abstract(21-8-2006).doc

232-mum-2001-abstract(21-8-2006).pdf

232-mum-2001-cancelled pages(9-3-2001).pdf

232-mum-2001-claims(granted)-(21-8-2006).doc

232-mum-2001-claims(granted)-(21-8-2006).pdf

232-mum-2001-correspondence(15-4-2008).pdf

232-mum-2001-correspondence(ipo)-(28-11-2006).pdf

232-mum-2001-drawing(21-8-2006).pdf

232-mum-2001-form 1(21-8-2006).pdf

232-mum-2001-form 18(22-2-2005).pdf

232-mum-2001-form 2(granted)-(21-8-2006).doc

232-mum-2001-form 2(granted)-(21-8-2006).pdf

232-mum-2001-form 24(28-12-2006).pdf

232-mum-2001-form 3(15-3-2006).pdf

232-mum-2001-form 3(9-3-2001).pdf

232-mum-2001-form 4(13-2-2006).pdf

232-mum-2001-form 5(9-3-2001).pdf

232-mum-2001-petition under rule137(15-5-2006).pdf

232-mum-2001-petition under rule138(15-5-2006).pdf

232-mum-2001-power of authority(29-6-2001).pdf

232-mum-2001-power of authority(30-01-2006).pdf

abstract1.jpg


Patent Number 215077
Indian Patent Application Number 232/MUM/2001
PG Journal Number 13/2008
Publication Date 28-Mar-2008
Grant Date 21-Feb-2008
Date of Filing 09-Mar-2001
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA
Applicant Address 1-1 MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 HIROFUMI WAKAYAMA C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA
2 MASAHIRO KOGA C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA
PCT International Classification Number F02M1/12
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2000-072363 2000-03-15 Japan