JPH05240037A - Egr device for engine - Google Patents

Abstract

PURPOSE:To shorten a secondary air path reduce the production cost by installing a switching means at the end opening position of the secondary air path which shuts an EGR path only at a low temperature and opens/closes so as to communicate the EGR path and the secondary air path. CONSTITUTION:An EGR path 16 is provided for communicating an exhaust path 12 and an intake path 4 to return back exhaust gas to an intake system. A secondary air path 40 is provided which opens in start upstream of an intake system and opens in the midway position of the EGR path 16 for using path of the EGR path 16 to supply air upstream of the intake system to an exhaust path 12. A switching means 42 is provided at the end opening position of the secondary air path 40 which shuts the EGR path at a low temperature and opens/closes so as to communicate the midway position of the EGR path 16 and the secondary air path 40. Consequently, the secondary air path is shortened, the production cost is reduced and the degree of freedom of the secondary air piping is raised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR device for an engine, and more particularly to an EGR device for an engine provided with an EGR passage for connecting an exhaust passage and an intake passage for returning exhaust gas to an intake system.
It relates to a GR device.

[0002]

2. Description of the Related Art An engine EGR device is provided with an EGR valve in the middle of an EGR passage when exhaust gas is recirculated to an intake passage, and the EGR valve is controlled to open and close in accordance with an engine operating state to clean the exhaust gas. To fulfill.

Further, there are turbochargers that utilize exhaust energy, which are turbochargers, and mechanical types that are superchargers, which improve output and fuel efficiency.

Further, the secondary air supply device is provided with a secondary air passage for supplying the secondary air to the exhaust passage by utilizing the negative pressure generated by the exhaust pulsation in the exhaust passage of the engine. The secondary air supply device purifies the secondary air supply device by supplying secondary air to the exhaust passage through the secondary air passage and secondarily burning the exhaust gas to oxidize HC and CO which are harmful components of the exhaust gas.

Further, as another secondary air supply device, as disclosed in Japanese Utility Model Laid-Open No. 61-53513,
A check valve that blocks the backflow of exhaust gas is installed in the middle of the metal pipe that connects the secondary air inlet of the catalytic converter and the secondary air supply hose, and the check valve is located between the check valve and the secondary air inlet. From the point, there was one that provided a bypass passage for guiding the exhaust gas to the exhaust gas management passage to the engine intake side.

As another secondary air control device, as disclosed in Japanese Utility Model Laid-Open No. 61-144214, secondary air is supplied to the exhaust system of an engine provided with an exhaust gas recirculation device. An EGR valve of the exhaust gas recirculation device is provided with a passage provided with a reed valve that operates by exhaust pulsation and supplies secondary air to the exhaust system and a control valve mechanism that controls opening and closing of the secondary air passage in the middle of the secondary air passage. Of the EGR negative pressure passage and the other end of the EGR negative pressure passage are provided so as to communicate with the carburetor venturi of the engine, and the one end side of the branch passage and the branch passage are connected in the middle of the EGR negative pressure passage. There was a device in which the other end side of the above was communicated with a pressure chamber provided in the actuator of the control valve mechanism.

[0007]

In the conventional engine, as shown in FIG. 4, the air cleaner 110 is used.
The secondary air device 152 that supplies the secondary air from the secondary air passage 140 to the exhaust passage 112 includes the secondary air passage 140 and the secondary air passage 14
An EGR device 154, which has a secondary air valve 146 provided midway through the exhaust passage 112 and recirculates the exhaust gas from the exhaust passage 112 into the combustion chamber 106, is provided in the EGR passage 116 and the EGR passage 116. EGR valve 1
18 and an EGR modulator 122. The secondary air passage 140 of the secondary air device 152 and the EGR passage 116 of the EGR device 154 are separately formed,
This causes an increase in the number of parts, complicates the configuration, increases manufacturing costs, is economically disadvantageous, and causes an increase in the size of the engine room, which is disadvantageous in practical use.

In some engines 102, the secondary air valve 146 and the exhaust passage 112 are separated from each other. In such a case, the secondary air pipe 144 forming the secondary air passage 140 becomes long, which increases the manufacturing cost and is economically disadvantageous, and the degree of freedom of piping of the secondary air pipe 144 is high. There was an inconvenience that was restricted.

[0009]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides an EGR device for an engine provided with an EGR passage for connecting an exhaust passage and an intake passage to recirculate exhaust gas to an intake system. In the above, in order to use a part of the EGR passage as a secondary air supply for supplying the air on the upstream side of the intake system to the exhaust passage, a secondary air opening at an upstream end of the intake system and ending at an intermediate end of the EGR passage. A passage is provided, and a switching means that shuts off the EGR passage only when the temperature is low and that opens and closes to connect the middle of the EGR passage and the secondary air passage is provided at a terminal opening portion of the secondary air passage. And

[0010]

By inventing as described above, at low temperature,
The switching means opens and closes the EGR passage so as to connect a part of the EGR passage and the secondary air passage,
Secondary air is supplied to the exhaust passage by using a part of the R passage for supplying secondary air for supplying air on the upstream side of the intake system to the exhaust passage.

When the temperature is high, the switching means operates so as to close the end portion of the secondary air passage to make a part of the EGR passage a normal EGR passage and recirculate the exhaust gas to the intake system.

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 3 show an embodiment of the present invention. In FIG. 2, 2 is an engine, 4 is an intake passage,
6 is a combustion chamber, 8 is a throttle valve, 10 is an air cleaner, and 12 is an exhaust passage. Combustion chamber 6 of the engine 2
Are connected to the air cleaner 10 by the intake passage 4. The intake passage 4 is divided on the upstream side by a dividing wall 4a into first and second divided intake passages 4-1 and 4-2 that function as a low load and a high load. A first throttle valve 8-1 is arranged in the first intake passage 4-1 and a second throttle valve 8-2 is arranged in the second intake passage 4-2.

An exhaust passage 12 is connected to the combustion chamber 6. A catalyst 14 is provided in the middle of the exhaust passage 12.
Are arranged.

Further, in the engine 2, a portion of the exhaust passage 12 upstream of the catalyst 14 and the first and second intake passages 4 are provided.
An EGR passage 16 that communicates with the downstream portions of the throttle valves 8-1 and 8-2 is provided. This EGR passage 1
An EGR valve 18 is provided on the downstream side of 6, that is, on the intake passage 4 side of the EGR passage 16.

An EGR modulator 22 is connected to the EGR valve 18 via a first communication passage 20. The EGR modulator 22 has a second communication passage 24.
Is connected to a portion of the EGR passage 16 upstream of the EGR valve 18.

Further, the intake manifold 26 constituting the intake passage 4 is provided with a water jacket 28. A temperature-sensitive vacuum switching valve (TVSV) 30 is arranged near the water jacket 28.

The temperature-sensitive vacuum switching valve (TVSV) 30 operates so as to be in an off state when the temperature exceeds the EGR set temperature T2 higher than the secondary air set temperature T1. The temperature-sensitive vacuum switching valve (TVSV) 30 is connected to the upstream portion of the first throttle valve 8-1 of the first intake passage 4-1 by the third connecting passage 32, and the second intake passage is formed by the fourth connecting passage 34. The first and second throttle valves 8-1, 8- of the intake passage 4-2 are connected to the upstream portion of the second throttle valve 8-2 of the passage 4-2 and are connected by the fifth connecting passage 36.
It is connected to a portion downstream of 2 and is connected to the EGR modulator 22 by a sixth connecting passage 38.

In addition, a part of the EGR passage 16 is opened at an upstream portion of the intake system for use as a secondary air supply for supplying the air on the upstream side of the intake system to the exhaust passage 12, and the EGR passage 16 is in the middle thereof. A secondary air passage 40 that opens to the end is provided in the portion, and the EGR passage 16 is blocked only at a low temperature in the end opening portion of the secondary air passage 40, and the middle of the EGR passage 16 and the secondary air passage 40 are connected. There is provided a switching means 42 for opening and closing so as to communicate with each other.

More specifically, the air cleaner 10 and the EGR
A secondary air pipe 44 connects a portion of the passage 16 that communicates with the second communication passage 24 with the side of the exhaust passage 12, and a secondary air passage 40 formed in the secondary air pipe 44 connects the inside of the air cleaner 10 It communicates with the EGR passage 16. A secondary air valve 46 is arranged at a downstream side portion of the secondary air passage 40.

A switching means 42 is provided at the end opening portion A of the secondary air passage 40. The switching means 42 is composed of, for example, a switching valve 48 and a temperature sensitive operation unit (not shown).

The temperature-sensing operation unit (not shown) is
That is, when the cooling water temperature T is lower than the secondary air set temperature T1 which is lower than the EGR set temperature T2, the EG
The R passage 16 is shut off, and the switching valve 48 is operated to connect the middle of the EGR passage 16 and the secondary air passage 40, and at the time of high temperature, that is, the cooling water temperature T is set to the secondary air set temperature T1. When it exceeds, the switching valve 4 is opened to shut off the secondary air passage 40 and open the EGR passage 16.
8 is operating.

Next, the operation will be described.

When the ignition switch (not shown) is turned on (102), it is compared (104) whether the cooling water temperature T is equal to or lower than the secondary air set temperature T1 or not, and the cooling water is compared. When the temperature T is equal to or lower than the set temperature T1 for the secondary air, the temperature sensing operation unit (not shown) operates the switching valve 48 to close the EGR passage 16 and open the secondary air passage 40 (106). ).

After the operation (106), it is compared (108) whether or not the cooling water temperature T exceeds the secondary air set temperature T1, and it is determined whether the cooling water temperature T is the secondary air set temperature 1 or 1. When the temperature exceeds, a temperature-sensing operation unit (not shown) closes the secondary air passage 40 and also causes the EGR passage 16 to be closed.
The switching valve 48 is operated (110) to open the valve.

Further, in the comparison (104), when the cooling water temperature T exceeds the secondary air set temperature T1, the switching valve 48 is operated (110).

Furthermore, when the cooling water temperature T is equal to or lower than the secondary air set temperature T1 in the comparison (108), the switching valve 48 is operated (106).

After the operation (110), it is compared whether or not the cooling water temperature T exceeds the EGR set temperature T2 (11
2) When the cooling water temperature T is equal to or lower than the EGR set temperature T2 in this comparison, the comparison (108) is performed, and when the cooling water temperature T exceeds the EGR set temperature T2, EG
Temperature-sensitive vacuum switching valve for R (TVS
V) 30 is turned off (114).

As a result, the secondary air passage 40 can be shortened, the manufacturing cost can be reduced, which is economically advantageous, and the shortening of the secondary air passage 40 reduces the piping of the secondary air pipe 44. The degree of freedom can be improved, which is practically advantageous.

In addition, a part of the EGR passage 16 is used for the secondary air supply for supplying the air on the upstream side of the intake system to the exhaust passage 12 by the temperature sensing operation unit (not shown), At low temperature, air can be supplied from the air cleaner 10 to the exhaust passage 12 and the catalyst 14 can be activated. At high temperature, the exhaust gas can be recirculated from the exhaust passage 12 to the intake passage 4 to purify the exhaust gas. It is advantageous.

The present invention is not limited to the above-mentioned embodiment, but various application modifications are possible.

For example, in the embodiment of the present invention, the switching means is composed of the switching valve and the temperature sensing operation unit.
For example, it is possible to provide a water temperature sensor that detects the cooling water temperature, provide a control unit that inputs a detection signal from the water temperature sensor, and control the opening / closing of the switching valve by the control unit according to the cooling water temperature. Is.

[0033]

As described in detail above, according to the present invention, a part of the EGR passage is started at the upstream portion of the intake system so as to be used as a secondary air supply for supplying the air on the upstream side of the intake system to the exhaust passage. A secondary air passage that opens and ends in the middle of the EGR passage is provided, and the EGR passage is blocked at the end opening portion of the secondary air passage only when the temperature is low.
Since the switching means for opening and closing is provided so as to connect the middle of the GR passage and the secondary air passage, the secondary air passage can be shortened, the manufacturing cost can be reduced, and it is economically advantageous, and the secondary air passage is also provided. By shortening, the degree of freedom of the piping of the secondary air pipe can be improved, which is practically advantageous.

[Brief description of drawings]

FIG. 1 is a flow chart of an EGR device for an engine showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an EGR device of the engine.

FIG. 3 is an enlarged view of a main part of an EGR device of the engine.

FIG. 4 is an engine EGR showing the prior art of the present invention.
It is a schematic block diagram of an apparatus.

[Explanation of symbols]

2 engine 4 intake passage 8 throttle valve 10 air cleaner 12 exhaust passage 16 EGR passage 18 EGR valve 22 EGR modulator 26 intake manifold 28 water jacket 30 temperature-sensitive vacuum switching valve (TVS)
V) 40 secondary air passage 42 switching means 44 secondary air pipe 46 secondary air valve 48 switching valve

Claims (1)

[Claims] 1. An EGR device for an engine, which is provided with an EGR passage for connecting an exhaust passage and an intake passage to recirculate exhaust gas to an intake system, wherein a portion of the EGR passage is provided with air on an upstream side of the intake system. EG is opened at the upstream portion of the intake system to be used for supplying secondary air to
A secondary air passage that opens to the end is provided in the middle portion of the R passage.
An EGR device for an engine, which is provided with switching means for opening and closing the GR passage and connecting the middle of the EGR passage and the secondary air passage.