JPH0643254U - Exhaust gas recirculation device - Google Patents

Abstract

(57) [Abstract] [Purpose] The load state of the engine 1 and the exhaust gas recirculation amount are accurately proportional to each other, and it is possible to effectively reduce the NOx generation amount without deteriorating the drivability. The exhaust gas recirculation device 8 is provided. The exhaust gas recirculation device 8 of the present invention includes two thin plates 6a having one or a plurality of opening holes 60 in an exhaust gas recirculation passage 5 which connects the exhaust pipe 2 and the intake pipe 3. 6b is overlapped, one thin plate 6a is fixed in the exhaust gas recirculation path, and the other thin plate 6b is set to be reciprocally rotatable according to the opening degree of the throttle valve 4.
Is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation device for suppressing emission of nitrogen oxides (hereinafter referred to as NOx) in exhaust gas discharged from an internal combustion engine.

[0002]

[Prior art]

 As one of the conventional exhaust gas recirculation devices, the exhaust gas is shunted from the exhaust pipe of an internal combustion engine, and the back pressure is reduced through a fixed throttle provided downstream of the carburetor throttle and upstream of the throttle valve. It is known to recirculate an amount of exhaust gas that is a function of the above.However, problems may occur due to foreign matter adhering to the throttle valve, corrosion of the aluminum body such as the intake pipe, and thermal effects on the carburetor. Therefore, as shown in FIG. 6, the exhaust gas recirculation passage 82 including the throttle 83 and the exhaust gas recirculation valve 84 that opens and closes by the intake negative pressure is usually used to exhaust the exhaust gas. A model is adopted in which the exhaust gas diverted from the pipe 80 is directly recirculated to the intake pipe 81 located downstream of the throttle valve 85. At that time, negative pressure such as intake negative pressure, venturi negative pressure, and air pump discharge pressure is adopted. Those utilizing control is performed for exhaust gas recirculation amount is common.

According to this type, when the engine 86 enters the operating state and enters the accelerating state, the opening degree of the throttle valve 85 increases, and the pores 87 provided in the intake passage wall upstream of the throttle valve 85. Negative pressure is generated. This negative pressure is transmitted to the negative pressure chamber 90 of the exhaust gas recirculation valve 84 shown in FIG. 7 through the pressure conduit 88, and the diaphragm 91 made of a flexible material is bent upward against the biasing force of the spring 93. As a result, the valve body 92 connected to the diaphragm 91 moves upward, and a gap is created between the seat portion 94 fixed inside the exhaust gas recirculation valve 84 and the valve body 92. Then, a part of the exhaust gas is recirculated through the exhaust gas recirculation passage 82 into the intake pipe having a negative pressure.

At the time of high load of the engine 86 in which the intake air amount to the engine 86 is large, the gap between the valve body 92 and the seat portion 94 becomes large, so that the exhaust gas recirculation amount increases. Therefore, the amount of NOx generated in the high load region of the engine 86 is reduced.

[0005]

[Problems to be solved by the device]

 In the above-mentioned exhaust gas recirculation device that directly recirculates exhaust gas into the intake pipe, the amount of exhaust gas recirculation is such that the difference between the engine exhaust pressure and the pressure in the intake pipe that communicates with the exhaust gas recirculation passage, and the passage of the throttle passage. Since it is uniquely determined only by the relationship with the area, the ratio of the exhaust gas recirculation amount to the intake air amount of the engine is relatively high in the low load region and is high in the high load region, especially due to the influence of the intake pipe pressure. Inevitably, the exhaust gas recirculation valve must be operated to control the exhaust gas recirculation amount so as to be proportional to the intake air amount of the engine.

However, the control of the exhaust gas recirculation valve in the above-described conventional exhaust gas recirculation device is performed by using the intake negative pressure generated by the opening of the throttle valve, and the intake negative pressure itself is controlled. When the exhaust gas recirculation valve is open, the degree of occurrence cannot be exactly proportional to the intake air amount of the engine, but rather is generated as an on / off signal to open and close the exhaust gas recirculation valve. The exhaust gas recirculation amount is determined by the difference between the engine exhaust pressure and the pressure in the intake pipe communicating with the exhaust gas recirculation passage. Naturally, it is difficult to reduce NOx effectively by controlling the exhaust gas recirculation amount accurately and flexibly in response to the engine load condition showing various changes only by controlling the exhaust gas recirculation valve. Met.

In FIG. 8, the horizontal axis represents the load of the engine itself, and the vertical axis represents the opening area of the valve body of the exhaust gas recirculation valve. As can be seen from the figure, the opening area of the valve body of the exhaust gas recirculation valve drastically changes between engine loads T1 and T2, and most of the engine load range is fully open or fully closed. It can be seen that the opening area of the valve body of the exhaust gas recirculation valve does not necessarily correspond to the load of the engine itself, and the NOx amount can be effectively reduced only by controlling the valve body of the exhaust gas recirculation valve. It is clear that the recirculated exhaust gas cannot be recirculated in order to reduce

In order to achieve the supply of the exhaust gas recirculation amount proportional to the intake air amount to the engine without being affected by the influence of the intake negative pressure, in addition to the control of the exhaust gas recirculation valve, a low load is applied. Some throttles are equipped with a variable throttle in the exhaust gas recirculation path that operates with intake negative pressure or venturi negative pressure so that the throttle area is reduced by, and the throttle area is increased under high load. It is not possible to completely remove the influence of the intake negative pressure to achieve the supply of recirculated exhaust gas to the engine in an amount proportional to the intake air amount, and to reduce the intake air amount to the engine at low engine load. The ratio of the amount of recirculated exhaust gas becomes unnecessarily high to facilitate the occurrence of surging phenomenon and misfire, while at high load, the ratio of the amount of recirculated exhaust gas to the intake air amount of the engine decreases to suppress the generation of NOx. Stop There is a problem in that it is difficult to reduce NOx efficiently from low load to high load, such as the effect of reducing the effect.

In view of the above problems, the present invention accurately proportions the intake air amount to the engine, in other words, the load state of the engine and the exhaust gas recirculation amount, resulting in deterioration of drivability and a complicated structure. It is a technical issue to be solved to provide an exhaust gas recirculation device that enables effective reduction of Nox without causing reduction.

[0010]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides an exhaust gas recirculation device having a throttle for controlling the amount of exhaust gas recirculation in the exhaust gas recirculation path and returning it to the intake pipe. By interlocking the opening area with the throttle valve opening, it increases as the throttle valve opening increases, that is, as the engine itself goes from a low load range to a high load range, and conversely When the degree of opening decreases, that is, when the engine itself changes from a high load range to a low load range, a technical measure is taken to reduce it.

Specifically, two thin plates provided with one or a plurality of opening holes are stacked, one of the two plates is fixed in the exhaust gas recirculation path, and the other is fixed to the throttle valve opening. By rotating the apertures of the two thin plates in an overlapping manner, the opening area of the variable diaphragm is determined by the overlapping state.

[0012]

[Action]

 Therefore, according to the exhaust gas recirculation system of the present invention described above, when the engine itself is under a low load, the throttle valve opening is small and the opening area of the variable throttle that is interlocked with the throttle valve opening is small. Since it is also small, it is possible to recirculate the suppressed small amount of exhaust gas recirculation. In this state, as described above, the load on the engine itself is small, so the amount of NOx generated in the exhaust gas is small, so the NOx reduction effect is not impaired, and the intake air of the engine is not reduced. Since the proportion of the exhaust gas recirculation amount in the amount is small, the stable combustion state of the engine is promoted and good drivability is realized. On the other hand, if the engine speed is increased or the engine itself is loaded with a high load, the throttle valve opening is also increased and is in an expanded state. The opening area of the variable throttle, which is linked to the opening degree, is also expanded, and the exhaust gas recirculation amount is also increased, so that the NOx generation amount increased due to the high load of the engine itself can be accurately measured. Correspondingly, it is possible to effectively reduce the amount of NOx generated, and also in terms of drivability, the engine burns with extremely high efficiency so as to generate high output. There is no problem even if the proportion of exhaust gas recirculation in the air increases.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. First, the structure of the exhaust gas recirculation device according to the present invention will be described. In FIG. 1, an engine 1 is provided with an exhaust pipe 2 and an intake pipe 3. A throttle valve 4 for adjusting the amount of intake air to the engine 1 is provided upstream of the intake pipe 3. Reference numeral 5 denotes an exhaust gas recirculation passage for recirculating exhaust gas, one end of which is opened to the exhaust pipe 2 and the other end of which is opened to the intake pipe 3 downstream of the throttle valve 4. Reference numeral 6 denotes a variable throttle provided to change the passage area of the exhaust gas recirculation passage 5, which is composed of two circular thin plates and is linked with the throttle valve 4 by a wire 7. ing. Further, the throttle valve 4 is linked with an accelerator pedal (not shown) by a link mechanism (not shown), and the opening becomes larger as the accelerator pedal (not shown) is depressed.

The variable diaphragm 6 will be further described. In FIG. 1, inside the housing 64, two concentric and identical circular thin plates 6a and 6b (hereinafter referred to as thin plate 6a) are provided with opening holes 60a and 60b for recirculating exhaust gas. And the thin plate 6b) are stacked to form the variable diaphragm 6. The thin plate 6b is rotatably supported and fixed by the thin plate 6a fixed inside the housing 64. Further, the thin plate 6b has an arm 61 integrally, and the arm 61 has the arm 61. By projecting to the outside of 64, an interlocking relationship is established with the throttle valve 4 via the wire 7.

FIG. 2 shows the interlocking relationship between the opening of the throttle valve 4 and the variable throttle 6. Reference numeral 20 denotes a throttle valve body provided in the intake pipe 3, an accelerator link 21 is integrally supported and fixed to the throttle valve 4 by a shaft 22, and an accelerator cable 23 is attached to the accelerator link 21. And is connected to an accelerator pedal (not shown). Further, one end of the wire 7 shown in FIG. 1 is also engaged with the accelerator link 21, and the other end of the wire 7 is a thin plate 6b forming a part of the variable diaphragm 6. The arm 61 is integrally attached and linked. Similarly, the thin plate 6b is rotatably supported and fixed by a shaft 65 of the thin plate 6a forming a part of the variable diaphragm 6. The arm 61 protrudes to the outside of the housing 64 through a minimum notch 64a provided in a part of the housing 64, and a support member 64b that is integral with the housing 64. It is elastically supported by the back spring 62 and completely sealed by the rubber seal 63.

Based on the above configuration, the operation of the exhaust gas recirculation device of the present invention will be described with reference to FIG. FIG. 3 shows the relationship between the load condition of the engine and the control of the passage opening area of the variable throttle 6 through which the exhaust gas recirculates. More specifically, the thin plate 6a that regulates the exhaust gas maximum circulation amount is shown. The state of the variable diaphragm 6 in which the overlapping state of the respective opening holes 60a and 60b provided in the thin plate 6b and the thin plate 6b is changed by the reciprocating rotation of the thin plate 6b is shown. 3a shows the passage opening area of the variable throttle 6 in a state where the accelerator pedal (not shown) is not depressed at all, that is, in the idling state, and FIG. 3b shows a state where the accelerator pedal (not shown) is fully depressed. The passage opening area of the variable diaphragm 6 at a certain time is shown.

When the accelerator pedal (not shown) is not depressed at all, the opening degree of the throttle valve 4 is set to the minimum by the accelerator link 21 which is in a connection relationship. At this time, the thin plate 6b is entirely biased by the back spring 62, and as shown in FIG. 3A, the thin plate 6b is set at a position of an angle difference θ with respect to the thin plate 6a. The overlapping state of the respective opening holes 60a and 60b provided in the thin plate 6b and the thin plate 6b is suppressed to the minimum. In this state, the passage opening area S1 of the recirculated exhaust gas is the minimum, and the ratio of the exhaust gas recirculation amount to the intake air amount of the engine 1 is naturally the minimum value, but the engine 1 itself also has a low load. Therefore, the amount of NOx generated in the exhaust gas remains only in a very small amount, and the NOx reduction effect is not impaired, and the exhaust gas recirculation amount is very small. Driveability can not be adversely affected.

When an accelerator pedal (not shown) is depressed, the linked accelerator link 21 begins to rotate (clockwise in FIG. 2), and the opening degree of the throttle valve 4 is expanded. . At the same time, the thin plate 6b integrated with the arm 61 also rotates (counterclockwise in FIG. 3) via the tension between the accelerator link 21 and the wire 7, and is shown in FIG. Further, the angle difference θ 1 with the thin plate 6a is reduced, and the overlapping state of the respective opening holes 60a and 60b provided in the thin plate 6a and the thin plate 6b is enlarged. That is, the passage opening area state of the variable diaphragm 6 shown in FIG. 3A shifts to the passage opening area state of the variable diaphragm 6 shown in FIG. 3B. In this state, the passage opening area of the recirculated exhaust gas is enlarged, and the ratio of the exhaust gas recirculation amount to the intake air amount of the engine 1 is also increased, and the opening degree of the throttle valve 4 is increased. Naturally, the NOx amount is effectively reduced in accordance with the NOx amount discharged from the engine 1 in which the load tends to increase.

When the accelerator pedal (not shown) is depressed to the maximum, the accelerator link 21 in the connected relation is rotated to the maximum in the rotatable range (the maximum in the clockwise direction in FIG. 2), and the throttle valve 4 is rotated. Maximize the opening. At the same time, the thin plate 6b, which is integrated with the arm 61, rotates through the tension of the accelerator link 21 and the wire 7 until the angle difference θ between the thin plate 6a and the thin plate 6a shown in FIG. (It becomes counterclockwise in FIG. 3), and the respective opening holes 60a and 60b provided in the thin plate 6a and the thin plate 6b are completely aligned as shown in FIG. 3b. In this state, the passage opening area S2 of the recirculated exhaust gas becomes the maximum, and naturally the ratio of the exhaust gas recirculation amount to the intake air amount of the engine 1 becomes the maximum value, and the high load state is established. It is possible to effectively reduce the amount of NOx that is exhausted from the engine 1 that is becoming more severe, and the engine 1 is also high in the influence on the drivability due to the large amount of exhaust gas recirculation. Since it burns efficiently, it does not pose a problem, and it does not cause a significant deterioration in operating performance such as reduced output or unstable combustion.

On the contrary, when the depression of the accelerator pedal (not shown) is weakened, the accelerator link 21 in the connecting relation is rotated in the opposite direction (counterclockwise in FIG. 2), and the throttle valve 4 is reduced, and at the same time, the thin plate 6b is also rotated in reverse by the urging force of the back spring 62 via the arm 61 (in FIG. 2, the thin plate 6b is rotated clockwise). The angle difference θ 2 between the thin plate 6a and the thin plate 6a is enlarged, and the overlapping state of the opening holes 60a and 60b provided in the thin plate 6a and the thin plate 6b is reduced. That is, the passage opening area state of the variable diaphragm 6 shown in FIG. 3B is shifted to the passage opening area state of the variable diaphragm 6 shown in FIG. 3A. In this state, the passage opening area of the recirculated exhaust gas is reduced, and the ratio of the exhaust gas recirculation amount to the intake air amount of the engine 1 is reduced, but the opening degree of the throttle valve 4 is reduced. As a result, the load on the engine 1 itself tends to decrease, and therefore the NOx amount can be effectively reduced in response to the NOx emission amount which is decreasing.

Therefore, in the exhaust gas recirculation device of the present invention, the thin plate 6b forming the variable throttle 6 is reciprocally rotated in association with the opening degree of the throttle valve 4, and the thin plate 6a and the thin plate 6b are reciprocally rotated. The exhaust gas recirculation amount is adjusted and limited by the change in the passage opening area of the recirculated exhaust gas, which is determined by the overlapping state of the exhaust gas. The characteristics of the exhaust gas recirculation device of the present invention having the above-described structure and operation will be described with reference to FIG. 4 on the premise of the above figures and description.

In FIG. 4, the horizontal axis represents the load of the engine 1 itself. The vertical axis represents the opening area of the variable throttle 6 and has a relationship in which the opening area S1 is expanded to S2 as the engine load T1 to T2 changes on the horizontal axis. Since the opening area of the variable throttle 6 is set so as to have an interlocking relationship with the opening degree of the throttle valve 4 that regulates the amount of intake air into the engine 1 as described above, as will be apparent from FIG. The control is possible according to the load of the engine 1 itself, and is suitable for effectively reducing the NOx amount by regulating the recirculation amount of the recirculated exhaust gas via the variable throttle 6. It enables recirculation of a large amount of exhaust gas recirculation. In other words, the control means of the variable throttle 6 that changes the passage opening area of the recirculated exhaust gas in association with the opening degree of the throttle valve 4 corresponding to the intake air amount into the engine 1 can be used for various operations. Under various conditions, the amount of NOx generated in the exhaust gas emitted by the engine 1 that makes various changes instantaneously or stepwise can be reduced or suppressed without adversely affecting the engine 1. be able to.

As another embodiment of the present invention, as shown in FIG. 5, an exhaust gas recirculation valve 30 for moving a poppet type valve body 31 up and down by using the negative pressure control method described in the prior art is provided. The same effect can be obtained by setting the variable throttle 6 of the present invention in the throttle portion of the exhaust gas recirculation device. In addition, in this example, the shape of the opening holes 60 provided in the thin plates 6a and 6b forming the variable diaphragm 6 is set to be circular, but, for example, the shape of the opening hole 60 is elliptical. By changing the setting, it is possible to change the overlapping state of the thin plate 6a and the thin plate 6b into various forms.

[0024]

[Effect of device]

 As described in detail above, according to the present invention, since the exhaust gas recirculation amount can be set according to the throttle valve opening, the relationship between the load state of the engine itself and the exhaust gas recirculation amount can be set arbitrarily. This makes it possible to respond to the increase and decrease in the amount of NOx generated in the exhaust gas very accurately. As with the conventional device described above, the surging phenomenon and misfire when the engine itself is in the low load range, and the high load of the engine itself It has an effect that the NOx generation amount can be effectively suppressed without causing a problem that the NOx amount reduction effect in the range is impaired.

Further, in the present invention, since it is not necessary to set an exhaust gas recirculation valve using a negative pressure control system having a complicated mechanism, it is much simpler than a conventional exhaust gas recirculation device. As a result, it has become possible to significantly reduce costs and improve assembly workability. Further, according to the present invention, the number, shape and position of the aperture holes formed in the two plates as a means for variably controlling the aperture area of the variable diaphragm are set in advance according to the engine performance / application, engine usage conditions and the like. Considering this, each can be freely selected, so it is possible to effectively supply the optimum exhaust gas recirculation amount to various engines that are developed and manufactured in a wide variety to meet the current wide range of applications. It also has an excellent effect.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an exhaust gas recirculation device embodying a variable throttle according to the present invention.

FIG. 2 is a schematic configuration diagram showing an interlocking relationship between a variable aperture and a throttle valve in the present invention.

FIG. 3 is an operation explanatory view of the variable throttle according to the present invention when the engine is under a low load or a high load, as viewed from the bottom.

FIG. 4 is a diagram showing the relationship between the load of the engine itself and the opening area of the variable diaphragm.

FIG. 5 is a vertical cross-sectional view of an exhaust gas recirculation device embodying another embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view of an exhaust gas recirculation device in the related art.

FIG. 7 is a vertical sectional view of an exhaust gas recirculation valve according to a conventional technique.

FIG. 8 is a diagram showing the relationship between the load of the engine itself and the opening area of the valve body of the exhaust gas recirculation valve.

[Explanation of symbols]

1 ... Engine, 2 ... Exhaust pipe, 3 ... Intake pipe, 4 ... Throttle valve, 5 ... Exhaust gas recirculation path, 6 ... Variable throttle, 6
a ... thin plate, 6b ... thin plate, 8 ... exhaust gas recirculation device, 60
… Opening holes

Claims (2)

[Scope of utility model registration request] 1. An exhaust gas recirculation device comprising an exhaust gas recirculation passage for returning exhaust gas diverted from an exhaust pipe of an engine into an intake pipe and a throttle on the exhaust gas recirculation passage, wherein the throttle has its opening. An exhaust gas recirculation device which is a variable throttle whose area increases as the opening of a throttle valve increases and shrinks as the opening of the throttle valve decreases. 2. The variable throttle is formed by stacking two thin plates having one or a plurality of opening holes, one thin plate being fixed in the exhaust gas recirculation path, and the other thin plate being the throttle. The exhaust gas according to claim 1, wherein the exhaust gas is rotated according to a valve opening degree, and the opening area is changed according to the overlapping state of the opening holes respectively provided in the two thin plates. Recirculation device.