JPS6130145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a secondary air introduction device for engines for automobiles and other vehicles. Conventionally, in this type of device, a differential pressure-responsive control valve has a chamber on one side of a diaphragm and a chamber on the other side of a diaphragm that communicate with each other via a throttle in a secondary air introduction passage connected to an intake passage of an engine. When the engine is decelerated,
Negative pressure on the downstream side of the throttle valve in the intake passage is guided from the negative pressure outlet into the chamber on one side via the negative pressure passage, and the valve is operated to the opening side, so that the engine moves into the combustion chamber. There is a known system in which secondary air is guided through this to prevent the aftertavern phenomenon, but in this case, the other side of the room is generally sealed and isolated from the atmosphere. In such a device, the negative pressure in the chamber on one side acts on the chamber on the other side through the throttle, so the differential pressure between the two chambers is eliminated relatively quickly and the valve closes. It closes relatively quickly, for example in a few seconds, and thus the amount of secondary air introduced through it is relatively small, which is insufficient especially when the engine is at low temperature, and this is a disadvantage that tends to cause the after-tavern phenomenon. Accompany. In other words, when the engine is at low temperature, the choke valve is on the closed side, so
If the engine is decelerated in this state, the air-fuel ratio within the combustion chamber will become extremely rich, resulting in the disadvantage that a small amount of secondary air will be insufficient.

The object of the present invention is to provide a device free from such inconveniences, and the secondary air introduction passage connected to the intake passage of the engine is provided with a chamber on one side of a diaphragm that communicates with each other through a throttle. A differential pressure-responsive control valve having a chamber on the other side is provided, and when the engine is decelerating, negative pressure on the downstream side of the throttle valve in the intake passage is supplied to the chamber from the negative pressure outlet through the negative pressure passage. In the case of a type in which the valve is operated to the open side by being guided into the chamber on the side, the chamber on the other side is connected to the negative pressure outlet slightly upstream of the closed position of the throttle valve in the intake passage. The two chambers are communicated via a pressure passage, and a valve that opens when the engine is at low temperature is interposed in the negative pressure passage leading to the chamber on one side.

Embodiments of the present invention will be described with reference to the attached drawings.

In the drawings, 1 indicates the intake passage of the engine, 2 indicates the carburetor on the upstream side thereof, 3 indicates the throttle valve, 4 indicates the choke valve, and 5 indicates the air cleaner at the upstream end.
A secondary air introduction path 6 is provided which branches off from this and communicates with the atmosphere via the cleaner 5, and a differential pressure responsive control valve 7, ie, an anti-aftertavern valve, is intervened in this. In the drawing, 6a indicates an intermediate aperture of the introduction path 6.

The control valve 7 is a differential pressure responsive type having a chamber 10 on one side and a chamber 11 on the other side that communicate with each other via a throttle 9 formed in a diaphragm 8. The side chamber 10 is connected to the negative pressure outlet 12 on the downstream side of the throttle valve 3 of the intake passage 1 via a negative pressure passage 13, and thus, when the engine is decelerated, the air flows into the side chamber 10. A negative pressure was introduced into the valve 7, through which secondary air was introduced.

Although the above is not particularly different from the conventional one, according to the present invention, the chamber 11 on the other side and the negative pressure outlet 14 slightly upstream of the closed position of the throttle valve 3 of the intake passage 1
The chamber 11 is communicated with through a negative pressure passage 15 so that the negative pressure of the outlet 14 is introduced into the chamber 11, and the low temperature of the engine, for example, the cooling water temperature of 75°C, is introduced into the negative pressure passage 13. The valve 16, which opens upon detecting the following, intervenes. In the illustrated example, the valve 16 is of a type that opens when both a low temperature of the engine and a high vehicle speed, for example 20 km/h or more, are detected. Actuation solenoid 16
The solenoid 16a is connected to a power source 18 via a water temperature sensor 17 consisting of a switch that closes when the cooling water temperature is low, and a relay contact that closes when a relay coil 19 is excited is located in between. 19a, and further connected to the power source 18 via the coil 19 and a vehicle speed sensor 20 consisting of a switch that closes at high vehicle speeds,
Thus, according to the operation of both sensors 17 and 20, the valve 1
6 was opened.

Furthermore, when switching from deceleration to acceleration of the engine, it is preferable to eliminate the differential pressure between the two chambers 10 and 11 as quickly as possible and stop the introduction of secondary air.This improves driver stability. It is advantageous to
In order to do this, for example, as shown in the second figure, the negative pressure passage 15 leading to the chamber 11 on the other side is connected to the negative pressure passage 13 leading to the chamber 10 on the one side via a side passage 22 having a throttle 21. This allows negative pressure to be introduced into the chamber 11 on the other side also through this.

To explain its operation, when the engine is low temperature and the vehicle speed is high, both sensors 17 and 20 open and the valve 16 opens, so the interior of the chamber 10 on one side is connected to the negative pressure outlet 12 on the downstream side. Exists in a connected state.

If the engine decelerates in this state, there will be a relatively large negative pressure in the negative pressure outlet 12 and a relatively large negative pressure in the negative pressure outlet 12.
A relatively small negative pressure close to atmospheric pressure is created in chamber 4, which acts in both chambers 10, 11, so that control valve 7 is opened and secondary air is introduced through it. Next, the pressure difference between the two chambers 10 and 11 is eliminated through the throttle 9, and the valve 7 is closed, but at this time, since the chamber 11 on the other side is at approximately atmospheric pressure as described above,
Compared to conventional systems in which this pressure is isolated from atmospheric pressure, it takes more or less time to eliminate the pressure difference, and thus the control valve 7 is kept open for a more or less long time, reducing the amount of secondary air. It is more or less large, thus effectively coping with enrichment of the air-fuel ratio in the combustion chamber during deceleration at low temperatures. Next, when the engine temperature rises, the water temperature sensor 17 opens and the valve 16 closes, so that no negative pressure is introduced into the chamber 10 on one side, in other words, the control valve 7 is activated even when the engine decelerates. It becomes a state where it does not. This is substantially the same even when the vehicle speed is low. In addition, when the speed is increased during operation at a low temperature described above, the inside of the negative pressure outlet 14 becomes a relatively large negative pressure, and the insides of both chambers 10 and 11 are equalized, but in the case shown in the second figure, The aforementioned side passage having the throttle 21 acts to speed up this pressure equalization, which is effective in improving drivability.

As described above, according to the present invention, when decelerating the engine at low temperature, the control valve is operated to guide the secondary air through the control valve, and the control valve is kept open for a relatively long period of time to direct the secondary air. Although the amount of the conventional method is relatively small, it has the effect of eliminating the above-mentioned disadvantages.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one example of the apparatus of the present invention, and FIG. 2 is an explanatory diagram of another example. 1... Intake passage, 3... Throttle valve, 6... Secondary air introduction path, 7... Control valve, 9... Throttle, 10...
Chamber on one side, 11... Chamber on the other side, 12, 14... Negative pressure outlet, 13, 15... Negative pressure outlet, 16...
Valve, 17...Water temperature sensor.

Claims (1)

[Scope of Claims] 1. A differential pressure-responsive control valve having a chamber on one side of a diaphragm and a chamber on the other side of a diaphragm that communicate with each other via a throttle in a secondary air introduction passage connected to an intake passage of an engine. When the engine is decelerating, the negative pressure downstream of the throttle valve in the intake passage is guided from the negative pressure outlet into the chamber on the one side through the negative pressure passage, and the control valve is operated to open. The chamber on the other side is connected to a negative pressure outlet slightly upstream of the closed position of the throttle valve of the intake passage via a negative pressure passage, and the A secondary air introduction device for an engine, characterized by intervening an on-off valve in a pressure passage that opens when the engine is at low temperature. 2. The secondary air introduction device for an engine according to claim 1, wherein the opening/closing valve is of a type that opens upon detection of both engine low temperature and high vehicle speed. 3. Claim 1 or 2, which communicates with the negative pressure passage leading to the room on the one side via a negative pressure passage leading to the room on the other side and a side passage having a throttle.
A secondary air introduction device in the engine described in 2.