JPH0144734Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention belongs to the technical field of secondary air supply devices for engines.

[Conventional technology]

An automobile engine is equipped with a secondary air supply device 6 as shown in FIG. 1 for the purpose of purifying exhaust gas. (For example, in 1987
−136615). This secondary air supply device 6 is
It mainly consists of a secondary air supply reed valve 2, a secondary air control valve 3, and a secondary air supply nozzle 4. In the secondary air supply device 6, the secondary air supply reed valve 2 generates exhaust pulsations (exhaust pressure pulsations in which positive pressure and negative pressure alternately repeat) occurring in the exhaust passage 5.
The valve is operated by the pump to introduce air. By the way, when the amount of exhaust gas becomes extremely large during high-load operation of the engine, the exhaust passage 5
There is positive pressure inside. Therefore, even when the engine is operating under high load, the secondary air supply reed valve 2
When the secondary air supply reed valve 2 is operated, exhaust gas may flow backward in the direction of the secondary air supply reed valve 2, and the secondary air supply reed valve 2 may be contaminated by the exhaust gas. As a countermeasure against this, in the secondary air supply device 6 as shown in FIG. 1, a secondary air control valve 3 is interposed between the secondary air supply reed valve 2 and the secondary air supply nozzle 4. ing. The secondary air control valve 3 has a valve body 8 that opens and closes the valve port 9 based on the negative pressure inside the intake manifold 7 (intake pipe negative pressure). When the engine is in a high-load operating state, the negative pressure in the intake pipe becomes small, so the negative pressure in the diaphragm chamber 11 becomes small, and as shown in FIG. Move down and valve port 9 is closed. Therefore, even if the inside of the exhaust passage 5 becomes positive pressure and the exhaust gas (arrow A in FIG. 2) flows backward, it will not reach the secondary air supply reed valve 2. can prevent contamination.

[Problem that the idea aims to solve]

However, such a secondary air supply device 6
In this case, when the engine is operated under high load,
There was a problem that noise was generated from the secondary air control valve 3. The secondary air control valve 3 is configured to open and close the valve port 9 depending on the balance between the negative pressure acting on the diaphragm chamber 11 and the pressing force of the compression coil spring 10. When the pressing force overcomes the negative pressure within the diaphragm chamber 11 (intake pipe negative pressure), that is, when the negative pressure acting within the diaphragm chamber 11 reaches a first predetermined negative pressure, the valve port 9 is closed. . However, at the moment when the valve port 9 is closed by the valve body 8, a slight negative pressure is acting within the diaphragm chamber 11, and the pressure exerted by the compression coil spring 10 is due to this negative pressure. The pressure is weakened, and the closing force with which the valve body 8 closes the valve port 9 becomes smaller. Therefore, when the pulsating pressure of the exhaust gas (arrow A in FIG. 2) acts on the valve body 8, the valve body 8 easily opens and closes the valve port 9 according to the number of pulsations of the pulsating pressure (arrow A). As a result, the valve body 8 and the valve seat 12 periodically collide with each other, resulting in noise. Therefore, an object of the present invention is to reliably prevent unnecessary operation of the secondary air control valve that occurs during high-load operation of the engine, and to suppress the generation of noise from the secondary air control valve.

[Means to solve the problem]

Therefore, in order to solve the above problems, the present invention provides a secondary air supply that only allows air to flow from the atmosphere to the exhaust passage in the middle of the secondary air supply passage that communicates the atmosphere and the exhaust passage. A secondary air control valve is interposed between the secondary air supply reed valve and the exhaust passage. The first diaphragm chamber is divided into two diaphragm chambers, the first diaphragm chamber being communicated with a negative pressure source via a negative pressure passage, the second diaphragm chamber being communicated with the atmosphere via an atmosphere opening port, and the first diaphragm chamber being communicated with the atmosphere through an atmosphere opening port. A compression coil spring is disposed in the diaphragm chamber, which is integrally attached to the diaphragm and which presses a valve body that opens and closes a valve port formed in the secondary air supply passage in a direction to close the valve port. In a secondary air supply system for an engine, which displaces a diaphragm by the pressing force of a compression coil spring to close a valve port when the negative pressure in the room falls below a first predetermined negative pressure, the negative pressure passage is connected to the engine. A negative pressure switching valve is installed to switch the communication between the first diaphragm chamber and the negative pressure source or the atmosphere depending on the operating state of the
This negative pressure switching valve switches the first diaphragm chamber to the atmosphere when the operating state is such that the negative pressure in the first diaphragm chamber becomes equal to or less than a second predetermined negative pressure, which is greater than the first predetermined negative pressure. The valve body is characterized in that the valve element communicates with the valve body and operates to close the valve port.

[Effect]

Negative pressure in the first diaphragm chamber when the valve body of the secondary air control valve closes the valve port due to the pressing force of the compression coil spring, that is, less than or equal to the second predetermined negative pressure that is greater than the first predetermined negative pressure. When the operating state is such that the negative pressure switching valve is activated and the negative pressure passage is communicated with the atmosphere. Therefore, the atmosphere is introduced into the first diaphragm chamber, and the valve body of the secondary air control valve is moved down only by the pressing force of the compression coil spring provided in the first diaphragm chamber, so that the valve port is opened. Obstructed.

【Example】

Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 3 is a diagram showing the overall configuration of an embodiment of the present invention, in which 1 is an air filter, 2 is a secondary air supply reed valve, 3 is a secondary air control valve, and 4 is a secondary air supply nozzle. be. The secondary air supply reed valve 2 and the secondary air control valve 3 are connected by a first secondary air supply passage 22, and the secondary air control valve 3 and the secondary air supply nozzle 4 are connected to each other by a first secondary air supply passage 22. The two secondary air supply passages 23 communicate with each other. Further, the air filter 1 and the secondary air supply reed valve 2 are communicated through a third secondary air supply passage 24. In the secondary air supply reed valve 2, the valve body 13 is actuated by exhaust pulsation (pulsation of exhaust pressure in which positive pressure and negative pressure are alternately repeated) generated in the exhaust passage 5.
Air (secondary air) is introduced into the exhaust passage 5. This valve body 13 is arranged so as to only allow air to flow from the atmosphere to the exhaust passage 5 side. The secondary air supply nozzle 4 is connected to the engine 2
It is opened in the exhaust passage 5 of No. 5 near the exhaust valve 27. The secondary air control valve 3 is composed of a valve housing 28 and a diaphragm device 29. A secondary air passage 30 is provided within the valve housing 28, with an inlet port 31 connected to the first secondary air supply passage 22 and an outlet port 32 connected to the second secondary air supply. They are connected to the passages 23, respectively. A valve seat 12 in which a valve port 9 is bored is disposed in the middle of the secondary air passage 30. The diaphragm device 29 has a diaphragm case 35 and a diaphragm 36, and the inside of the diaphragm case 35 is divided into a first diaphragm chamber 11 and a second diaphragm chamber 38 by the diaphragm 36.
It is divided into. The first diaphragm chamber 11 is connected to the intake manifold (negative pressure source) 7 via a negative pressure passage 39 . The second diaphragm chamber 38 is always open to the atmosphere through an atmosphere opening 41 formed in the diaphragm case 35. A compression coil spring 10 that presses the diaphragm 36 is arranged within the first diaphragm chamber 11 . The diaphragm 36 has a valve port 9 for the secondary air passageway 30 extending through the second diaphragm chamber 38.
A rod 43 extending into the more upstream space 45 is connected. At the tip of the rod 43, there is a valve port 9.
A valve body 8 is attached to open and close the valve. As can be seen from FIG. 3, the compression coil spring 10 presses the diaphragm 36 in the direction in which the valve body 8 closes the valve port 9. The secondary air control valve 3 having the above-mentioned configuration is configured so that the negative pressure acting in the first diaphragm chamber 11 through the negative pressure passage 39 is equal to or higher than a first predetermined negative pressure that overcomes the pressing force of the compression coil spring 10. When the pressure decreases, the diaphragm 36 is sucked against the pressing force of the compression coil spring 10 to open the valve port 9, and when the negative pressure becomes lower than the first predetermined negative pressure, the diaphragm 36 is sucked against the pressing force of the compression coil spring 10. to close the valve port. An electromagnetic negative pressure switching valve 5 is provided in the middle of the negative pressure passage 39.
1 are arranged, and the negative pressure passages 39 are connected to the first negative pressure passages 5 with the electromagnetic negative pressure switching valve 51 as the boundary.
2 and a second negative pressure passage 53. The electromagnetic negative pressure switching valve 51 has a first port 54, a second port 55, and a third port 56, and also includes a valve body 57 and an electromagnetic coil 58 for switching communication between these ports. There is. When the electromagnetic coil 58 is powered, the electromagnetic negative pressure switching valve 51 operates as shown in FIG.
The valve body 57 is moved in the direction of arrow P to connect the first port 54 and the second port 55, and when the electromagnetic coil 58 is not being supplied with power, the valve body 57 is moved in the direction of arrow Q. The first port 54 and the third port
and the port 56 of the. The first port 54 of the electromagnetic negative pressure switching valve 51 is connected to the first negative pressure passage 52
The second port 55 is connected to the intake manifold 7 via a second negative pressure passage 53 to the first diaphragm chamber 11 . Further, the third port 56 is open to the atmosphere. 61 is a negative pressure switch that controls power supply to the electromagnetic negative pressure switching valve 51;
The inside of the diaphragm case 62 is the diaphragm 63
A first diaphragm chamber 64 partitioned by
and a second diaphragm chamber 65. Second
In the diaphragm chamber 65 of the diaphragm 6
3 has an electrical contact 66 on its surface, and an electrical contact 66 on its surface.
Electric contacts 67 are provided on the inner wall surface of the diaphragm case 62 facing the diaphragm case 62, and these electrical contacts 66 and 67 constitute an electric switch. The first diaphragm chamber 64 is open to the atmosphere through an opening 68 formed in the diaphragm case 62, and the second diaphragm chamber 65 is opened to the atmosphere through a small hole 69 formed in the diaphragm case 62. It communicates with the inside of the intake manifold 7. Further, a compression coil spring 70 is disposed within the second diaphragm chamber 65 to press the diaphragm 63 in a direction in which the electrical contacts 66 and 67 open. The negative pressure switch 61 closes electrical contacts 66 and 67 as shown in FIG. 3 when the intake pipe negative pressure is larger than the set value, and closes the electrical contacts 66 and 67 when the intake pipe negative pressure is smaller than the set value. It is a so-called on-off switch configured to open. The set value of the negative pressure switch 61 is the negative pressure in the first diaphragm chamber 11 when the valve port 9 is closed by the pressing force of the compression coil spring 10 of the secondary air control valve 3, that is, the negative pressure in the first diaphragm chamber 11. The electrical contacts 66 and 67 are set to turn on and off at a negative pressure in an operating state that is a second predetermined negative pressure greater than the first predetermined negative pressure. In addition, the electromagnetic coil 58 of the electromagnetic negative pressure switching valve 51
is electrically connected to a battery 72 via a negative pressure switch 61 and an ignition switch 71. The operation of this embodiment based on the above configuration will be explained. When the engine 25 is in a low-medium load operating state, the intake pipe negative pressure is large, and the electrical contacts 66 and 67 of the negative pressure switch 61 are closed, as shown in FIG. Therefore, the electromagnetic negative pressure switching valve 51 is supplied with power and communicates between the first port 54 and the second port 55. Therefore, intake pipe negative pressure is introduced into the first diaphragm chamber 11 of the secondary air control valve 3 via the negative pressure passage 39. The intake pipe negative pressure during this low-medium load operating state is much higher than the set pressure when the secondary air control valve 3 closes the valve port 9, that is, the first predetermined negative pressure, so the diaphragm 36 It is attracted against the pressing force of the spring 10, and the valve port 9 is opened. Therefore, since the pulsating pressure in the exhaust passage 5 is transmitted to the secondary air supply reed valve 2, the valve body 13 is opened and closed according to the number of pulsations of the pulsating pressure, and the secondary air supply nozzle 4 is opened and closed. Secondary air is supplied into the exhaust passage 5 through the exhaust passage 5. On the other hand, when the engine 25 is in a high-load operating state, the intake pipe negative pressure becomes small. Then, the intake pipe negative pressure is applied to the first diaphragm chamber 11 of the secondary air control valve 3.
Electrical contacts 66 and 67 of the negative pressure switch 61 are opened when the negative pressure within the engine reaches a second predetermined negative pressure or less, which is greater than the first predetermined negative pressure. Therefore, power supply to the electromagnetic negative pressure switching valve 51 is stopped, and the first port 54 and the third port 56 are communicated with each other. Therefore, atmospheric pressure is introduced into the first diaphragm chamber 11 of the secondary air control valve 3, and the valve port 9 is closed only by the pressing force of the compression coil spring 10. In this case, since no negative pressure acts on the first diaphragm chamber 11, the closing force of the secondary air control valve 3 becomes the largest. Therefore, even if the pulsating pressure of exhaust gas acts on the valve body 8 as shown by arrow A in FIG. 4, the valve body 8 will not open the valve port 9, and the valve body 8 and the valve seat 1 There is no noise caused by periodic opening and closing collisions. Although a specific embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and includes various embodiments within the scope of the claims for utility model registration. For example, as a means of detecting the operating state of the engine, regardless of the negative pressure switch, the negative pressure in the first diaphragm chamber of the secondary air control valve is determined from the intake air amount, fuel injection amount, etc. The second pressure is greater than the predetermined negative pressure.
It may be possible to indirectly detect an operating state in which the pressure is below a predetermined negative pressure.

[Effect of the idea]

As described above, according to the present invention, when the engine is in a high-load operating state, the negative pressure in the first diaphragm chamber of the secondary air control valve is the first predetermined negative pressure, that is, the pressing force of the compression coil spring is the first predetermined negative pressure. When the negative pressure in the first diaphragm chamber becomes a second predetermined negative pressure that is greater than the negative pressure when the valve port is closed by the valve body, the negative pressure switching valve is operated to switch the first diaphragm chamber to the second predetermined negative pressure. Since atmospheric pressure is introduced into the room, it is possible to avoid weakening the pressing force of the compression coil spring due to negative pressure when the valve port is blocked, and it is possible to avoid increasing the closing force of the secondary air control valve. can. Therefore, even if the pulsating pressure of exhaust gas acts on the valve body, the valve body will not open the valve port.
Noise generation due to periodic collisions between the valve body and the valve seat can be prevented.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing a conventional secondary air supply system for an engine. FIG. 1 is an overall configuration diagram of the conventional secondary air supply system, and FIG.
An explanatory diagram of the operation in the secondary air supply device of FIG. 1,
3 and 4 are diagrams showing a secondary air supply device for an engine according to an embodiment of the present invention, and FIG.
4 is an overall configuration diagram of the secondary air supply device, and FIG. 4 is an explanatory diagram of the operation of the secondary air supply device of FIG. 3. 2... Secondary air supply reed valve, 3... Secondary air control valve, 5... Exhaust passage, 6... Secondary air supply device, 8... Valve body, 9... Valve port, 10... Compression coil spring, 11...first diaphragm chamber,
38... Second diaphragm chamber, 22... First secondary air supply passage, 23... Second secondary air supply passage, 24... Third secondary air supply passage, 39...
... Negative pressure passage, 52... First negative pressure passage, 53...
second negative pressure passage, 35... diaphragm case,
36...Diaphragm, 41...Atmospheric release port, 5
1...Negative pressure switching valve (electromagnetic negative pressure switching valve).

Claims (1)

[Scope of Claim for Utility Model Registration] A reed valve for secondary air supply that only allows air to flow from the atmosphere to the exhaust passage side, located in the middle of a secondary air supply passage that communicates the atmosphere with the exhaust passage; A secondary air control valve is interposed between the secondary air supply reed valve and the exhaust passage.
and a second diaphragm chamber, the first diaphragm chamber being communicated with a negative pressure source via a negative pressure passage, and the second diaphragm chamber being communicated with the atmosphere via an atmosphere opening; A compression coil spring is disposed in the first diaphragm chamber, which is integrally attached to the diaphragm and which presses a valve element that opens and closes a valve port formed in the secondary air supply passage in a direction to close the valve port. The above 1st
In a secondary air supply device for an engine, the diaphragm is displaced by the pressing force of a compression coil spring to close the valve port when the negative pressure in the diaphragm chamber becomes equal to or lower than a first predetermined negative pressure. A negative pressure switching valve is interposed in the pressure passage to switch the first diaphragm chamber to communicate with the negative pressure source or the atmosphere depending on the operating state of the engine,
This negative pressure switching valve switches the first diaphragm chamber when the operating state is such that the negative pressure in the first diaphragm chamber becomes equal to or less than a second predetermined negative pressure that is greater than the first predetermined negative pressure. A secondary air supply device for an engine, which communicates with the atmosphere and operates to close a valve port by the valve body.