GB1583676A

GB1583676A - Internal combustion engine ignition timing

Info

Publication number: GB1583676A
Application number: GB3051377A
Authority: GB
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1976-07-21
Filing date: 1977-07-20
Publication date: 1981-01-28
Also published as: AU2687377A; IT1079987B; CA1075547A; NL174286B; FR2359283B1; AU512405B2; SE7708382L; NL174286C; DE2732802A1; JPS5315440U; SE413538B; FR2359283A1; NL7708067A; JPS5338763Y2

Description

(54) IMPROVEMENTS RELATING TO INTERNAL COMBUSTION ENGINE IGNITION TIMING (71) We, HONDA GIKEN KOGYO KABUSHIKI KAISHA, a Japanese body corporate of No. 27-8, 6-chome, Jingumae, Shibuya-ku, Tokyo, 150 Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to ignition timing control apparatus of a spark ignition internal combustion engine having an intake passage provided with a throttle valve, and having a vacuum operated device for advancing the ignition timing.

Known apparatus has employed a threeway electromagnetic valve for connecting either one of two ports in the engine intake passage to an ignition advance chamber in the ignition timing device. The first port communicates with the engine intake passage at a location downstream from the throttle valve, while the second port communicates with the engine intake passage at a location slightly upstream from the throttle valve in the closed position. A solenoid in the three-way electromagnetic valve is energized when an electrical switch closes in response to low engine temperature.

According to the present invention there is provided, in a spark ignition internal combustion engine having an intake passage provided with a throttle valve, and having an ignition timing device including an ignition advance chamber, ignition timing control apparatus comprising: a first vacuum passage communicating with the intake passage downstream from the throttle valve, a second vacuum passage communicating with the intake passage upstream from the throttle valve in the closed position of the latter, each said vacuum passage being connected to the ignition advance chamber, and means sensitive to engine temperature for opening said first vacuum passage to the ignition advance chamber only when the engine temperature is low, wherein said second vacuum passage is permanently open to the ignition advance chamber but is permanently throttled as compared with said first vacuum passage so as to enable the ignition timing to be advanced via said first vacuum passage when the engine temperature is low.

Such an arrangement permits the replacement of the electromagnetic three-way valve of the prior art by a less expensive and less complicated solenoid operated two-way valve. This substitution is made possible by throttling the second vacuum passage as compared to the first vacuum passage; such a two-way electromagnetic valve may then be placed in the first vacuum passage.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure I is a schematic diagram showing a known arrangement for controlling the ignition timing of an internal combustion engine; and Figure 2 is a schematic diagram showing the relevant parts of an engine according to this invention.

Referring to the drawings, in the known arrangement shown schematically in Figure 1 an intake passage a of an internal combustion engine has a throttle valve b and a first port c at a location downstream therefrom.

A second port d communicates with the passage a at a location slightly on the upstream side of the throttle valve b in closed position. A first vacuum passage e is connected to the first port c and a second vacuum passage g communicates with the second port d. A delay valve f is operatively positioned in the second passage g.

An electromagnetic three-way valve k connects the second passage g to an ignition advance chamber h through a port j when the valve k is not energized. When the valve k is energized by a temperature sensitive switch m the port j is closed and a port i is opened so that the first vacuum passage e is connected to the ignition advance chamber h. A check valve n is provided in the first vacuum passage e. The first port c and the second port d are both approximately the same size.

The electromagnetic three-way valve k is of necessity relatively complicated in structure and therefore relatively expensive.

Referring now to the embodiment of the present invention shown in Figure 2, the intake passage 1 of an internal combustion, engine has a throttle valve 2 mounted therein. A first port 3 communicates with the intake passage 1 at a location downstream from the throttle valve 2 and communicates with a first vacuum passage 5. A second port 4 communicates with the intake passage 1 slightly on the upstream side of the closed position of the throttle valve 2 and is connected to a second vacuum passage 7. Both vacuum passages 5 and 7 are connected to an ignition advance chamber 8 of an ignition timing device of the engine.

The first port 3 is substantially larger than the second port 4 so that the second vacuum passage 7 is permanently throttled as compared to the first vacuum passage 5. An electromagnetic valve 9 is operatively interposed in the first vacuum passage 5. The valve 9 opens whenever its solenoid coil 9a is energized upon closing of an electrical switch 10, which is sensitive to engine temperature and closes whenever the engine temperature is below a predetermined value. A delay valve 6 is operatively interposed in the second vacuum passage 7.

With regard to the relative sizes of the ports 3 and 4, if the first port 3 is a round hole of 3 mm in diameter, for example, a good result is obtained when the second port 4 comprises a round hole of one-third the diameter of the first port, or 1 mm in diameter.

In operation, when the engine temperature is cold, the throttle valve 2 may be in proximity to its closed position. When the electromagnetic valve 9 opens, vacuum pressure at the first port 3 acts through the valve 9 on the ignition advance chamber 8 to advance the ignition timing of the engine.

At this time the second port 4 is at atmospheric pressure or in the proximity thereof and this positive pressure is introduced through the second vacuum passage 7 into the ignition advance chamber 8. However, because the first port 3 has a relatively large diameter, the vacuum pressure from the first port substantially overcomes the influence of the positive pressure in second vacuum passage 7. Then, when the vehicle driven by the engine is cruising at a relatively low throttle opening, if the engine has completed its warmup to close the electromagnetic valve 9, the first port 3 is disconnected from the ignition advance chamber 8, so that said chamber 8 is subjected only to the pressure obtained at the second port 4.

As will be understood from the foregoing explanation, the second vacuum passage 7 is throttled to a greater extent than the first vacuum passage 5; this construction makes it possible to change the temperaturecontrolled electromagnetic valve from the previously employed three-way valve type to a two-way valve type, that is, a simple switch valve type, and therefore is effective in making the structure simpler and less expensive.

WHAT WE CLAIM IS: 1. In a spark ignition internal combustion engine having an intake passage provided with a throttle valve, and having an ignition timing device including an ignition advance chamber, ignition timing control apparatus comprising: a first vacuum passage communicating with the intake passage downstream from the bottle valve, a second vacuum passage communicating with the intake passage upstream from the throttle valve in the closed positon of the latter, each said vacuum passage being connected to the ignition advance chamber, and means sensitive to engine temperature for opening said first vacuum passage to the ignition advance chamber only when the engine temperature is low, wherein said second vacuum passage is permanently open to the ignition advance chamber but is permanently throttled as compared with said first vacuum passage so as to enable the ignition timing to be advanced via said first vacuum passage when the engine temperature is low.

2. An engine as claimed in claim 1, wherein said second vacuum passage is permanently throttled at the port whereby it opens into the intake passage, such port being smaller than the port whereby said first vacuum passage opens into the intake passage.

3. An engine as claimed in claim 1 or 2, wherein the said means sensitive to engine temperature comprises a solenoid valve operatively interposed in said first vacuum passage, an electrical circuit for energizing said solenoid valve to permit flow through said first vacuum passage to the ignition advance chamber, and an electrical switch in said electrical circuit, said switch being sensitive to engine temperature and acting to open said solenoid valve when the engine temperature is low.

4. An engine as claimed in any of claims 1 to 3, including a delay valve operatively interposed in said second vacuum passage.

5. A spark ignition internal combustion engine having ignition timing control appar

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the valve k is not energized. When the valve k is energized by a temperature sensitive switch m the port j is closed and a port i is opened so that the first vacuum passage e is connected to the ignition advance chamber h. A check valve n is provided in the first vacuum passage e. The first port c and the second port d are both approximately the same size. The electromagnetic three-way valve k is of necessity relatively complicated in structure and therefore relatively expensive. Referring now to the embodiment of the present invention shown in Figure 2, the intake passage 1 of an internal combustion, engine has a throttle valve 2 mounted therein. A first port 3 communicates with the intake passage 1 at a location downstream from the throttle valve 2 and communicates with a first vacuum passage 5. A second port 4 communicates with the intake passage 1 slightly on the upstream side of the closed position of the throttle valve 2 and is connected to a second vacuum passage 7. Both vacuum passages 5 and 7 are connected to an ignition advance chamber 8 of an ignition timing device of the engine. The first port 3 is substantially larger than the second port 4 so that the second vacuum passage 7 is permanently throttled as compared to the first vacuum passage 5. An electromagnetic valve 9 is operatively interposed in the first vacuum passage 5. The valve 9 opens whenever its solenoid coil 9a is energized upon closing of an electrical switch 10, which is sensitive to engine temperature and closes whenever the engine temperature is below a predetermined value. A delay valve 6 is operatively interposed in the second vacuum passage 7. With regard to the relative sizes of the ports 3 and 4, if the first port 3 is a round hole of 3 mm in diameter, for example, a good result is obtained when the second port 4 comprises a round hole of one-third the diameter of the first port, or 1 mm in diameter. In operation, when the engine temperature is cold, the throttle valve 2 may be in proximity to its closed position. When the electromagnetic valve 9 opens, vacuum pressure at the first port 3 acts through the valve 9 on the ignition advance chamber 8 to advance the ignition timing of the engine. At this time the second port 4 is at atmospheric pressure or in the proximity thereof and this positive pressure is introduced through the second vacuum passage 7 into the ignition advance chamber 8. However, because the first port 3 has a relatively large diameter, the vacuum pressure from the first port substantially overcomes the influence of the positive pressure in second vacuum passage 7. Then, when the vehicle driven by the engine is cruising at a relatively low throttle opening, if the engine has completed its warmup to close the electromagnetic valve 9, the first port 3 is disconnected from the ignition advance chamber 8, so that said chamber 8 is subjected only to the pressure obtained at the second port 4. As will be understood from the foregoing explanation, the second vacuum passage 7 is throttled to a greater extent than the first vacuum passage 5; this construction makes it possible to change the temperaturecontrolled electromagnetic valve from the previously employed three-way valve type to a two-way valve type, that is, a simple switch valve type, and therefore is effective in making the structure simpler and less expensive. WHAT WE CLAIM IS:

1. In a spark ignition internal combustion engine having an intake passage provided with a throttle valve, and having an ignition timing device including an ignition advance chamber, ignition timing control apparatus comprising: a first vacuum passage communicating with the intake passage downstream from the bottle valve, a second vacuum passage communicating with the intake passage upstream from the throttle valve in the closed positon of the latter, each said vacuum passage being connected to the ignition advance chamber, and means sensitive to engine temperature for opening said first vacuum passage to the ignition advance chamber only when the engine temperature is low, wherein said second vacuum passage is permanently open to the ignition advance chamber but is permanently throttled as compared with said first vacuum passage so as to enable the ignition timing to be advanced via said first vacuum passage when the engine temperature is low.

atus substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.