JPH0441234Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a fast idle device for a chiyoke valveless carburetor that improves the effectiveness of engine braking during deceleration.

[Prior Art] In the case of a normal engine, a very rich air-fuel ratio is required when starting at a low temperature (during cranking). Therefore, in the case of a general carburetor, the chioke valve is fully closed, allowing a very rich air-fuel ratio (3 to 5), and extremely low temperatures (-20
℃ or below), the air-fuel ratio is set to 1 to 2, and after the engine is fully detonated, the choke valve is slightly opened to set the air-fuel ratio to about 8 to 10. However, in the case of a choke valveless carburetor, if the throttle valve is opened to the first idle opening during cranking, it is difficult to obtain the air-fuel ratio necessary for starting, so the throttle must be closed during cranking. It is necessary to inject a rich air-fuel mixture from downstream of the throttle (normal idle opening) and open the throttle after the engine has completely exploded to maintain the appropriate air-fuel ratio. For example, in JP-A-54-13834, by providing a starting air-fuel mixture passage whose effective area is adjusted by a valve that operates depending on the engine rotation speed and temperature, the engine rotation speed is adjusted to the level required for warm-up operation. A valve-less carburetor has been proposed that maintains the engine temperature at an optimum value and automatically starts idling operation after warming up.

[Problems to be solved by the invention] The first idle opening degree of the current automatic engine yoke carburetor is constant regardless of acceleration/deceleration, which reduces the effectiveness of engine braking for a while after starting at low temperatures. Furthermore, according to the above-mentioned Japanese Patent Application Laid-Open No. 54-13834, the solenoid valve is driven so that the engine speed is appropriate according to the engine temperature, and the starting air-fuel mixture is supplied to facilitate starting. Although results were obtained, since the starting fuel was primarily adjusted using a solenoid valve, there was a problem in that the air-fuel ratio could not be adequately controlled during engine startup and warm-up under various conditions. .

The purpose of this invention is to accurately control the air-fuel mixture that is mapped according to each condition when starting the engine in a valveless carburetor, and to improve the effectiveness of engine braking during deceleration. It is something to do.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a first idle position in a vacuum passage led out from a bore downstream of a throttle valve in a choke valveless carburetor. A set vacuum actuator is provided to completely warm up the throttle valve by cutting off the negative pressure of the actuator when the manifold negative pressure in the pilot negative pressure passage, which is provided separately from the negative pressure passage, exceeds a set value. A release valve that maintains the current idle opening degree is provided to create a fast idle device.

Equipped with such a device, it is possible to secure fast idle by regulating the rotation speed during high-speed no-load operation when cold, and when decelerating, it detects manifold negative pressure below the set value and activates the release valve. to release the first idle opening and improve the effectiveness of the engine brake.

[Embodiment] Fig. 1 shows an embodiment in which the present invention is applied to a compound vaporizer.
Next, secondary throttle valves 6 and 7 are installed. An air bleed pipe 8 is inserted into the center of the main fuel passage and opens into a float chamber 10 via a main jet 9. In addition, a feedback solenoid valve 11 is provided on the side of the float chamber 10, and a warm-up solenoid valve 13 is installed in the passage between the bottom of the float chamber 10 and the air bleed pipe 8. The bottom of the float chamber 10 and the step port 14 downstream of the secondary throttle valve 7
Start richer solenoid 1 in passage 15 between
Place 6. On the other hand, a slow cut solenoid valve 17 is disposed in the middle of the slow system passage 18. 19 is a bypass port, 20 is an idle port, and 21 is an idle adjustment screw.

The shaft of the primary throttle valve 6 has a
As shown in the figure, a first lever 22 is provided so that the arm 25 of the idle speed control unit 24 comes into contact with it, and a second lever 23 is provided as shown in FIG.
is provided and brought into contact with the first idle device.

FIG. 2 shows the configuration of the first idle device, in which negative pressure intake ports 26a and 26b are provided in the bore downstream of the throttle valve 6, and negative pressure passages 27 and 28 are led out, respectively. Negative pressure passage 2
7 is connected to a negative pressure chamber 31 of a first idle set vacuum actuator 30 via a throttle 29. When manifold negative pressure is introduced into this negative pressure chamber 31, the rod 34 fixed to the diaphragm 33 is pulled while pressing the spring 32. The tip of the rod 34 is pin-jointed to one end of a swinging plate 36 supported by a rotating shaft 35. The swinging plate 36 includes a wax element 37 that moves the thermowax-filled piston in and out depending on the temperature of the cooling water, and a first idler that is rotated by the extension of the movable part (plunger) of the wax element 37 and returned by a spring 38. A cam 39 is attached. The tip of the first idle cam 39 is brought into contact with a second lever 23 attached to the shaft of the primary throttle valve 6. The second negative pressure passage 28 has a first idle release valve 40. This valve 40 is connected to the negative pressure chamber 4 by a diaphragm 41.
1 and a valve chamber 42, and a negative pressure passage 27 is provided on the valve chamber 42 side.
A branch passage 43 is communicated between the throttle 29 and the actuator 30, and a leak port 44 is provided in a portion thereof. When the boost pressure is -500 mmHg or more, the release valve 40 is closed by pressing the valve toward the seat side by the force of the spring 45, but when the boost pressure is about -500 to -550 mmHg, the diaphragm is pulled in and the valve is opened, i.e. decelerated. When the release valve 40 is opened, the negative pressure of the actuator 30 is released and the fast idle state is released.

The above operations are performed by a mapping method that translates 15 or more virtual addresses through a storage allocation diagram (logic board) that references actual main memory locations in a computer (not shown).

Next, an example of the function and mapping of each part will be shown.

Idle speed control 24 Open the throttle valve 6 to the first idle opening after the engine has completely exploded. In other words, it operates when the engine speed is 400 rpm or more, turns on the idle switch, maps the coolant temperature, and checks for abnormalities using the trigger pulse output. An example of mapping is shown below.

Below 0℃ 1800r.p.m 0～10℃ 1500r.p.m 10～20℃ 1100r.p.m 20～40℃ 800r.p.m Feedback solenoid 11 Map according to cooling water temperature.

0℃ or less Duty 0% (full rich) 0~20℃ Duty 20% 20~40℃ Duty 40% 40℃ or more Feedback control Slow cut solenoid valve 17 Same control as the current one, for example, open the slow system at 200 rpm or less.

Warm-up enricher solenoid valve 13 Also performs enrichment based on the throttle valve opening and changes in trigger pulse output. In particular, the amount increased during acceleration varies depending on the temperature. Warm-up amount increase mapping is performed depending on the cooling water temperature.

-10℃ or less Duty 80% -10 to 0℃ Duty 70% 0 to 10℃ Duty 60% 10 to 20℃ Duty 40% 20 to 40℃ Duty 20% 40 to 50℃ Duty 10% During acceleration -10℃ or less Duty 100% 4sec -10 to 0℃ Duty 100% 2sec 0 to 10℃ Duty 80% 2sec 10 to 20℃ Duty 80% 2sec 20 to 40℃ Duty 70% 2sec These are mapped according to the output (TPS).
Secure 2/3 of the above duty with TPS output of 55% or more.

Start richer solenoid valve 16 Map the cooling water temperature.

-10°C or less Duty 80% -10°C to 0°C Duty 60% 0 to 10°C Duty 40% 10 to 20°C Duty 20% 20 to 40°C Duty 10% These are duties where the engine speed is 200 rpm or less. When the engine speed is 200 to 400r.pm, it is 1/2 of the above table, and when it is 400r.pm or more, it is 0.

[Effects of the invention] As mentioned above, this invention supplies a rich air-fuel mixture to the engine from downstream of the throttle valve when starting the engine, and after the engine has completely exploded, the fuel coming out of the primary main nozzle is made richer than usual to warm up the engine. The slow zone near the end can be corrected by feedback controlled slow system fuel. Particularly during deceleration, the negative pressure of the first idle set vacuum actuator is cut off to increase the A/F ratio and improve the effectiveness of engine braking.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the valveless carburetor of the present invention, and FIG. 2 is a sectional view of a first idle cut circuit. 6... Throttle valve, 27, 28... Negative pressure passage, 30... First idle set vacuum actuator, 40... Release valve.

Claims (1)

[Scope of utility model registration request] A first idle set vacuum actuator that secures the first idle position is provided in the negative pressure passage led out from the bore downstream of the slot valve, and the manifold negative pressure in the pilot negative pressure passage provided separately from the negative pressure passage is set to the set value. In the above case,
A first idle device for a choke valveless carburetor, characterized in that a release valve is provided to cut off the negative pressure of the actuator and maintain the idle opening of the slot valve in a fully warmed-up state.