JPS6233097Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an exhaust gas recirculation device for an engine that recirculates a portion of the engine exhaust gas to the intake system to actively lower the fuel combustion temperature, thereby reducing the amount of nitrogen oxides generated in the exhaust gas as much as possible.

In an engine equipped with this type of exhaust gas recirculation device, the ideal amount of exhaust gas recirculation that can maintain good exhaust characteristics (especially NOx generation amount), output characteristics, fuel efficiency, etc. depends on the engine load. As shown by curve ₁ in FIG. 1, the load changes by drawing two-stage curves ₁ a and ₁ b with different changing trends in the low load range and the middle and high load range. As a method of approximating the actual engine exhaust recirculation amount to this ideal exhaust recirculation amount curve ₁ , two exhaust recirculation valves are installed together as in the exhaust recirculation device shown in Japanese Utility Model Application Publication No. 114350/1983, and the low load region A method was adopted in which the amount of exhaust recirculation was controlled separately in medium and high load ranges, and a single exhaust recirculation valve was used, and this exhaust recirculation valve was controlled by a transducer controlled by the engine exhaust pressure. The method is known.

However, in the former case, there is a problem of high manufacturing costs due to the use of two relatively expensive exhaust gas recirculation valves, and in the latter case, due to the operating characteristics of the transducer, the exhaust gas recirculation amount curve As shown by the dash-dotted line ₂ in Fig. 1, the rise in the initial stage of operation is steep, so if we try to approximate this exhaust recirculation amount curve ₂ to the ideal exhaust recirculation amount curve ₂ in the low load range, we will In the load range, the amount of exhaust recirculation becomes excessive, which deteriorates the combustion characteristics and causes a drop in output.On the other hand, in the middle and high load regions, the exhaust recirculation amount curve ' ₂ becomes the ideal exhaust recirculation amount curve.
If an attempt was made to approximate ₁ , the exhaust gas recirculation amount would be insufficient in the low load range, which would impair the exhaust characteristics, which was a conflicting problem.

Furthermore, while an exhaust gas recirculation device (exhaust pressure type exhaust recirculation device) using a transducer has the advantage of being able to obtain an exhaust gas recirculation amount proportional to the engine load (i.e. exhaust pressure), the transducer Due to the structure of the user (described later), there is a drawback that there is a concern that the amount of exhaust gas recirculated may be momentarily excessive, especially during low-load operation. In other words, a transducer generally has a valve body attached to a diaphragm that operates in response to fluctuations in exhaust pressure, and the valve body opens and closes an atmosphere opening provided in a negative pressure pipe to adjust the amount of atmospheric dilution of negative pressure. By doing so, the magnitude of negative pressure can be corrected according to exhaust pressure (load), but
In this case, since the above-mentioned valve body is installed in a diaphragm type, there is a risk that the above-mentioned valve body may cause surging due to the influence of the pressure pulsation of the exhaust pressure, and in some cases, the above-mentioned valve body may momentarily become damaged due to surging. This may cause the negative pressure that has not been diluted to the atmosphere to be momentarily introduced into the negative pressure chamber of the exhaust recirculation valve, causing the amount of exhaust gas recirculation to momentarily become excessive. The phenomenon of instantaneous excessive exhaust recirculation due to surging of the valve body is more noticeable during low-load operation, where the amount of intake air is small and combustion stability is relatively poor, than during medium- to high-load operation. .

In view of the above-mentioned problems, the present invention provides a method using one exhaust recirculation valve and a transducer.
A negative pressure port and a second negative pressure port that function at medium and high loads are opened, and the exhaust recirculation valve is controlled by the negative pressure from the first negative pressure port at low loads, and at medium and high loads. By controlling by the negative pressure from the second negative pressure port via the transducer, the exhaust gas recirculation amount is insufficient in the low load range due to the operating characteristics of the transducer, and in the middle and high load ranges. Prevents excessive exhaust recirculation and instantaneous excessive exhaust recirculation in the low load range due to the structure of the transducer, and maintains engine performance such as exhaust characteristics and output characteristics in good condition throughout the entire load range. This device was developed for the purpose of providing a low-cost exhaust gas recirculation device that provides a low-cost exhaust gas recirculation system that includes an exhaust gas recirculation passage that communicates the exhaust system and intake system of an engine, and a negative pressure operation that controls the opening and closing of the exhaust gas recirculation passage. In an engine exhaust recirculation system that is equipped with an exhaust recirculation valve and recirculates part of the exhaust gas to the intake system, when the throttle valve opens by a predetermined opening degree and is located upstream of a fully closed throttle valve, A first negative pressure port located on the downstream side; A first negative pressure passage leads the negative pressure from the pressure port to the negative pressure chamber of the exhaust recirculation valve after diluting it through the atmosphere opening port, and the negative pressure from the second negative pressure port is diluted by the exhaust pressure of the engine. A second negative pressure passage leads to the negative pressure chamber of the exhaust recirculation valve via a transducer that corrects the A negative pressure passage control device that opens the recirculation valve by a predetermined amount and operates the exhaust recirculation valve with negative pressure from the second negative pressure passage when the throttle valve opening is larger than the set opening. It is.

Hereinafter, the exhaust gas recirculation device for the engine of the present invention will be explained as follows.
To explain based on the embodiment shown in Figures 5 through 5, Figure 2 shows an overall system diagram of an exhaust gas recirculation device _Z1 installed in an automobile engine according to an embodiment of the present invention. Reference numeral 1 denotes an engine body, 2 an intake pipe constituting an intake system X, 3 an exhaust pipe constituting an exhaust system Y, 4 a carburetor, 5 an air cleaner, and 6 a throttle valve.

This exhaust gas recirculation device Z ₁ is installed in the middle of an exhaust gas recirculation passage 9 that connects the exhaust pipe 3 with a position on the downstream side of the intake air from the throttle valve 6 of the intake pipe 2. A negative pressure operated exhaust recirculation valve 10 is provided which is driven by the exhaust gas recirculation passage 9 to control the opening and closing of the exhaust recirculation passage 9. By adjusting the degree of opening of the exhaust recirculation valve 10, The amount of exhaust gas recirculated from the exhaust system Y side to the intake system X side can be controlled. The recirculation of this exhaust gas is stopped when the engine 1 is in a no-load operation state, and is recirculated to the intake system X side only during load operation.
In that case, the negative pressure passage control device 11 is used to control the exhaust gas recirculation amount along an exhaust gas recirculation amount curve that approximates the ideal exhaust gas recirculation amount curve as the load increases.
and a transducer 12 are attached.

The negative pressure passage control device 11 selectively maintains the first negative pressure inlet 36 and the second negative pressure inlet 37 under negative pressure by means of a valve body 17 that switches and operates according to the negative pressure supplied into the negative pressure chamber 16. It is comprised of a negative pressure operated three-way switching valve that operates to communicate with the outlet 35. The negative pressure outlet 35 of the negative pressure control device 11 is connected to the negative pressure chamber 1 of the exhaust gas recirculation valve 10.
3, and drives the valve body 14 of the exhaust gas recirculation valve 10 according to the strength of the negative pressure supplied to the negative pressure chamber 13, thereby controlling the amount of exhaust gas recirculation from the exhaust system Y to the intake system X. It is made to be. The negative pressure chamber 16 of this negative pressure passage control device 11 is a negative pressure for controlling a switching valve formed in the intake pipe 2 so as to open on the intake downstream side of the throttle valve 6 at a first valve open position slightly open from the fully closed position. It is communicated with port 20. Therefore, when the throttle valve 6 is fully closed (no-load operation) as shown in FIG. 2 or in the first open position (low-load operation) as shown in FIG. Since the negative pressure is supplied to the valve body 17, the valve body 17 is driven against the spring force of the spring 18 and communicates the first negative pressure inlet 36 with the negative pressure outlet 35 (the first
valve position), and when the throttle valve 6 is in another position as shown in Fig. 4 (during medium or high load operation),
Since the negative pressure port 20 for controlling the switching valve is located on the intake upstream side of the throttle valve 6, positive pressure is supplied into the negative pressure chamber 16, and the negative pressure outlet 35 is connected to the first negative pressure inlet 36 by the valve body 17. The communication with the second negative pressure inlet 37 is interrupted (second valve position).

Also, of the first negative pressure inlet 36 and the second negative pressure inlet 37 of this negative pressure passage control device 11, the first negative pressure inlet 36
is located on the intake upstream side of the throttle valve 6 in the intake pipe 2 and in the throttle valve fully closed position, and when the throttle valve 6 is in the first open position (the third
In the figure), a first negative pressure port 21 formed at a position downstream of the intake air from the throttle valve 6 is connected to the first negative pressure passage 31, and a second negative pressure inlet 37 is connected to the first negative pressure port 21 through a first negative pressure passage 31. Furthermore, the second valve is located on the upstream side of the intake air and the throttle valve 6 is further opened than the first valve opening position.
When the valve is in the open position, it is communicated with a second negative pressure port 22 formed at a position on the intake downstream side of the throttle valve 6 via a second negative pressure passage 32, respectively. A transducer 12, which will be described later, is interposed at an intermediate position of the second negative pressure passage 32. The first negative pressure inlet 36 is open to the atmosphere through an atmosphere opening 51 to which an air cleaner 39 is attached, and an orifice 40 for adjusting negative pressure is interposed in the middle thereof.

The transducer 12 has a constant pressure chamber 3 formed at a position upstream of the exhaust gas recirculation valve 10 in the exhaust gas recirculation passage 9 by a diaphragm 50 with a valve body 43.
8 and the exhaust pressure chamber 41 that communicates with An atmospheric pressure chamber 4 that communicates with a third negative pressure port 23 formed so as to be located on the downstream side of the intake air and is simultaneously opened to the atmosphere.
It is divided into two chambers. Also, atmospheric pressure chamber 4
On the second side, there is a negative pressure pipe 48 that passes through the atmospheric pressure chamber 42 and communicates with the atmospheric pressure chamber 42 at an intermediate portion thereof.
is installed. This negative pressure pipe 48 is interposed within the second negative pressure passage 32 and acts as a part of the second negative pressure passage 32, and the opening 45 formed toward the atmospheric pressure chamber 42 is connected to the diaphragm 50. It is opened and closed as appropriate by a valve body 43.

Next, to explain the operation of the exhaust gas recirculation device _Z1 of this embodiment, first, when the engine is operated with no load, the throttle valve 6 is in the fully closed position (second position).
), the switching valve control negative pressure port 20 is located on the intake downstream side of the throttle valve 6, and the first negative pressure port 21 is located on the intake upstream side.
The negative pressure passage control device 11 is set to the first valve position by the negative pressure extracted from the switching valve control negative pressure port 20. Therefore, the negative pressure chamber 13 of the exhaust gas recirculation valve 10 is loaded with positive pressure extracted from the first negative pressure port 21, and the exhaust gas recirculation valve 10 is loaded with positive pressure extracted from the first negative pressure port 21.
The valve body 14 closes the exhaust gas recirculation passage 9 and acts to prevent the exhaust gas E from flowing toward the intake system X side.

Next, as shown in FIG. 3, when the throttle valve 6 is opened to the first valve opening position and the engine 1 is operated at a low load, the switching valve control negative pressure port 2
0 and the first negative pressure port 21 are both the throttle valve 6
Since the negative pressure passage control device 11 is located on the downstream side of the intake air, the negative pressure passage control device 11 is held in the first valve position, and the negative pressure extracted from the first negative pressure port 21 is passed from the air cleaner 39 through the atmosphere opening port 51. First negative pressure inlet 3
6 is diluted by the atmosphere introduced into the negative pressure chamber 13.
Loaded within. Therefore, the exhaust gas recirculation valve 10 opens slightly (low-load valve opening position), and an amount of exhaust gas E corresponding to the passage area is recirculated from the exhaust system Y side to the intake system X side. Control of the exhaust gas recirculation valve 10 by the negative pressure extracted from the first negative pressure port 21 is as follows:
The exhaust gas recirculation amount is maintained only while the throttle valve 6 is between the first valve opening position and the second valve opening position _. This corresponds to a curved portion within the range of area A from a to load b. In this case, by adjusting the negative pressure applied to the negative pressure chamber 13 by the negative pressure adjustment orifice 40 of the negative pressure passage control device 11, the exhaust gas recirculation amount curve ₃ within the range of region A can be adjusted to the ideal exhaust gas. The reflux curve ₁ can be approximated as much as possible.

Next, during medium load operation when the throttle valve 6 is opened to the second opening position (Fig. 4), the switching valve control negative pressure port 20 and the third negative pressure port 23 are connected to the intake upstream side of the throttle valve 6. The other first and second negative pressure ports 21 and 22 are located on the downstream side of the intake air.

Therefore, the negative pressure passage control device 11 is set to the second valve position, and the first negative pressure port 21 is disabled. Moreover, the exhaust pressure chamber 41 of the transducer 12
is loaded with the exhaust pressure in the exhaust gas recirculation passage 9, and the atmospheric pressure chamber 42 is loaded with the positive pressure and atmospheric pressure extracted from the third negative pressure port 23, and the valve body 43 of the diaphragm 50 is loaded with both of these. The position is maintained at a position where the pressure in the chamber is balanced and with the opening 45 of the negative pressure pipe 48 kept open. Therefore, the exhaust recirculation valve 10 is opened to a greater extent than the low load opening position (medium load opening position) by the low negative pressure extracted by the second negative pressure port 22, and the In this case, a larger amount of exhaust gas E is recirculated than during low-load operation.

During high-load operation when the throttle valve 6 is in the fully open position as shown by reference numeral 6' in FIG. . Therefore, the negative pressure extracted from the second negative pressure port 22 is applied to the negative pressure chamber 13 of the exhaust gas recirculation valve 10 via the negative pressure pipe 48 of the transducer 12 and the load passage control device 11, and the The valve 10 is opened to allow the exhaust gas E to flow back to the intake system 3. Since the negative pressure extracted from the negative pressure port 23 is applied, the valve body 43 is displaced toward the atmospheric pressure chamber 42, as shown by reference numeral 43' in FIG. 4, and closes the opening 45 of the negative pressure pipe 48. Therefore, the second negative pressure port 22
The negative pressure extracted from the exhaust gas recirculation valve 10 and loaded into the negative pressure chamber 13 of the exhaust recirculation valve 10 is lower than the drawing pressure at the time of medium load and is not diluted by the atmosphere. becomes even lower than during medium-load operation, and the exhaust gas recirculation valve 10 is opened to a greater extent than the medium-load valve opening position, so that a large amount of exhaust gas E is recirculated to the intake system X side.

The exhaust gas recirculation amount during this high load operation and during the medium load operation is determined by the exhaust recirculation amount curve ₃ shown in FIG.
This corresponds to the curved part in area B of . That is, according to the exhaust gas recirculation device _Z1 of this embodiment, the negative pressure and the second negative pressure automatically extracted from the first negative pressure port 21 according to the valve opening degree of the throttle valve 6 due to engine load fluctuations. The exhaust gas recirculation valve 10 is selectively controlled by the negative pressure extracted from the port 22, and the amount of exhaust gas recirculated to the intake system follows an exhaust gas recirculation amount curve _l3 that approximates the ideal exhaust gas recirculation amount curve _l1 . As a result, it will be increased or decreased.

Furthermore, in this embodiment, the valve body 43 of the transducer 12 is connected to the first
Since the exhaust recirculation valve 10 is directly controlled by the negative pressure extracted from the negative pressure port 21 and diluted to the atmosphere, instantaneous damage caused by surging of the valve body 43 during low load operation is avoided. This will prevent an excessive amount of exhaust gas recirculation.

Next, to explain the effects of the present invention, the exhaust gas recirculation device of the present invention includes a first negative pressure port in the intake system of the engine for extracting negative pressure to operate the exhaust gas recirculation valve at low load, and a middle, A second negative pressure port is formed to extract the negative pressure that operates the exhaust recirculation valve during high loads, and the exhaust recirculation valve is controlled by the negative pressure extracted from the first negative pressure port and diluted by the atmosphere during low loads. However, during medium and high loads, the exhaust recirculation valve is controlled by the negative pressure extracted from the second negative pressure port and corrected according to the engine exhaust pressure by the transducer. If the engine is controlled only by the negative pressure applied through the transducer in the entire load range of the engine, there will be insufficient exhaust recirculation in the low load range and insufficient exhaust recirculation in the medium and high load range. This prevents the instantaneous excessive exhaust recirculation amount in the low load range due to excessive flow rate phenomena and the structure of the transducer itself, and approximates the exhaust recirculation amount in response to load fluctuations to the ideal exhaust recirculation amount, thereby reducing the engine's full load. This has the effect that various performances such as exhaust characteristics and output characteristics can be maintained well in the range.

In addition, by selectively controlling one exhaust recirculation valve using the negative pressure from the first negative pressure port and the negative pressure from the second negative pressure port, the amount of exhaust gas recirculated with respect to engine load fluctuations can be approximated to the ideal amount of exhaust recirculation. Therefore, in cases where two relatively expensive exhaust recirculation valves are used to approximate the exhaust recirculation amount to the ideal exhaust recirculation amount, as in the exhaust recirculation device shown in Japanese Utility Model Application Publication No. 55-114350. There is also the effect that the manufacturing cost can be lowered in comparison.

[Brief explanation of the drawing]

Fig. 1 is a graph for explaining the exhaust gas recirculation amount characteristics in a conventional exhaust recirculation system, Fig. 2 is an overall system diagram of an exhaust recirculation system according to an embodiment of the present invention, and Figs. FIG. 5 is an explanatory diagram of the operation of the exhaust gas recirculation device shown in the figure, and FIG. 2 is a graph for explaining the exhaust gas recirculation amount characteristics in the exhaust gas recirculation device. 1... Engine, 2... Intake pipe, 3... Exhaust pipe, 6... Throttle valve, 9... Exhaust recirculation passage,
DESCRIPTION OF SYMBOLS 10... Exhaust recirculation valve, 11... Negative pressure passage control device, 12... Transducer, 13... Negative pressure chamber, 21... First negative pressure port, 22... Second negative pressure port, 31... ...first negative pressure passage, 32...second negative pressure passage, X...intake system, Y...exhaust system.

Claims (1)

[Scope of utility model registration request] The engine exhaust recirculation system includes an exhaust recirculation passage that communicates the engine exhaust system and the intake system, and a negative pressure-operated exhaust recirculation valve that controls opening and closing of the exhaust recirculation passage, and recirculates part of the exhaust gas to the intake system. In the device,
When the throttle valve is located upstream of the fully closed throttle valve and opens by a predetermined setting opening degree, the first negative pressure port located downstream of the throttle valve and the throttle valve located upstream of the first negative pressure port and opened by the above setting When the opening is greater than the opening degree, the second negative pressure port located downstream and the first negative pressure port dilute the negative pressure from the first negative pressure port through the atmosphere opening port and then lead it to the negative pressure chamber of the exhaust recirculation valve. a negative pressure passage; a second negative pressure passage that guides the negative pressure from the second negative pressure port to the negative pressure chamber of the exhaust recirculation valve via a transducer that corrects the negative pressure with engine exhaust pressure; and a throttle valve. When the opening degree of the throttle valve is less than the set opening degree above, the exhaust recirculation valve is opened by a predetermined amount by the negative pressure from the first negative pressure passage, and when the throttle valve opening degree is greater than the set opening degree, the negative pressure from the second negative pressure passage is opened. An exhaust gas recirculation device for an engine, comprising: a negative pressure passage control device that operates an exhaust gas recirculation valve by pressure.