JPH056143U - Exhaust gas recirculation control valve - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the opening of the control valve fluctuates due to variations in the negative pressure from the intake pipe of the engine, the circulation amount of exhaust gas can be kept constant. [Composition] In an exhaust gas recirculation control valve that recirculates exhaust gas into the engine to reduce harmful components, a cylindrical auxiliary valve is provided in a part of the control valve, and this auxiliary valve is used as a valve seat. It was slidably inserted into the vertical hole with a predetermined gap. [Effect] Even if the negative pressure varies and the opening of the control valve fluctuates, the circulation amount of exhaust gas can be kept constant, and it is inexpensive and reliable without using a special device for keeping the negative pressure constant. It becomes a high exhaust gas recirculation control valve.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas recirculation control valve used in an exhaust gas recirculation system for an internal combustion engine such as an automobile.

[0002]

[Prior Art]

 FIG. 8 is a schematic diagram of a conventional exhaust gas recirculation system. In the figure, 1 is an engine having a combustion chamber 2, 3 is an exhaust pipe through which the exhaust gas from the combustion chamber 2 passes, and 4 is an EGR that cools the exhaust gas. (Exhaust Gas Recirculation) cooler 5 is an EGR valve (exhaust gas recirculation control valve) for introducing the exhaust gas cooled by the EGR cooler 4 into an intake pipe (not shown) of the engine 1, and 6 is a negative pressure signal. A control valve that responds to adjust the opening of the exhaust gas passage, and a diaphragm 7 that forms a negative pressure chamber 8 and operates the control valve 6 by a differential pressure.

The exhaust gas from the exhaust pipe 3 is cooled by the EGR cooler 4 and then introduced into the EGR valve 5, and the exhaust gas whose recirculation amount is adjusted by the adjusting valve 6 is supplied to the intake pipe. As a result, the exhaust gas is re-combusted in the engine 1, and harmful nitrogen oxides (Nox) in the exhaust gas are reduced. Although the exhaust gas from the exhaust pipe 3 has a high temperature, the exhaust gas in the EGR valve 5 is cooled by being cooled by the EGR cooler 4, so that the diaphragm 7 is not deteriorated by heat.

FIG. 5 is a detailed cross-sectional view of the EGR valve 5, which is described in Japanese Utility Model Application No. 62-55430 as an example. In the figure, 10 is a housing made of aluminum die casting, and has an exhaust gas passage 9 inside. Reference numeral 11 is a passage inlet for the exhaust gas from the exhaust pipe 3 of the engine, and 12 is a passage outlet for introducing the exhaust gas into the intake pipe of the engine. A valve seat 13 is provided in the middle of the exhaust gas passage 9, and the valve seat 13 is opened and closed by the control valve 6. Reference numeral 14 denotes a shaft portion connected to the control valve 6, which is supported by a bearing portion 15 and slides. Reference numeral 16 is a holder arranged below the bearing portion 15 to prevent the ingress of carbon dioxide in the exhaust gas to the bearing portion 15 side, and 17 and 18 are two holding plates holding the diaphragm 7 between them. , 18 are joined to the ends of the shaft portion 14 by caulking 19. Reference numeral 20 denotes a case fixed to the outer peripheral portion of the housing 10 from above the diaphragm 7, and a negative pressure chamber 8 is formed in the space between the diaphragm 7 and the case 20. Reference numeral 21 is a spring stretched between the pressing plate 7 and the case 20, and biases the control valve 6 in the valve closing direction. Reference numeral 22 is a negative pressure introducing pipe for introducing negative pressure from the intake pipe of the engine.

In the EGR valve 5 configured as described above, first, exhaust gas introduced from the exhaust pipe 3 of the engine 1 is introduced into the exhaust gas passage 9 from the passage inlet 11. The exhaust gas is introduced from the passage outlet 12 to the intake pipe in accordance with the opening degree of the control valve 6 that operates according to the magnitude of the negative pressure introduced from the negative pressure introduction pipe 22 into the negative pressure chamber 8. Here, the exhaust gas is mixed with a mixture of fuel and air, supplied to the combustion chamber 2 and burned. This reduces the emission of nitrogen oxides (Nox), which is a harmful component in the exhaust gas. Further, carbon or the like in the exhaust gas enters from the exhaust gas passage 11 to the passage outlet 12, but the holder 16 prevents the carbon from entering the bearing portion 15 side.

The circulation amount of the exhaust gas is adjusted according to the opening degree of the control valve 6. However, since the shape of the control valve 6 is a disk, the circulation amount of the exhaust gas is shown in FIG. As shown in the enlarged view, it is determined by the gap between the inclined surface 13a of the valve seat 13 and the outer peripheral surface 6a of the control valve 6, and therefore, as can be seen from the characteristic diagram shown in FIG. The degree of opening and the circulation amount of exhaust gas are proportional.

[0007]

[Problems to be solved by the device]

 In the conventional exhaust gas recirculation control valve configured as described above, since the control valve 6 is made of a disc shape, the opening of the control valve and the circulation amount of exhaust gas are proportional to each other. There was a problem in that the degree of opening of the control valve varied, and as a result, the amount of exhaust gas circulated changed and reliability decreased.

The present invention has been made in order to solve the above problems, and it is possible to keep the amount of circulation of exhaust gas constant even if the opening of the control valve fluctuates due to variations in negative pressure. The purpose is to obtain an exhaust gas recirculation control valve.

[0009]

[Means for Solving the Problems]

 The exhaust gas recirculation control valve according to the present invention includes a housing having an exhaust gas passage therein, and an exhaust gas circulated from an engine exhaust pipe provided in the housing to the intake pipe through the exhaust gas passage. A control valve for controlling the amount, a valve seat with which the control valve abuts and the exhaust gas passage is closed by the control valve, and a bearing portion connected to the control valve and provided in the housing. A freely supported shaft part, a holder supported at the lower part of the bearing part to prevent carbon in the exhaust gas from entering the bearing part side, and a differential pressure attached to the end part of the shaft part. In an exhaust gas recirculation control valve equipped with a diaphragm that opens and closes the control valve by means of the above, and a case that forms a differential pressure in this diaphragm, a vertical hole wall of the valve seat and a predetermined hole are provided in a part of the control valve. Slide across a gap Characterized in that an auxiliary valve.

[0010]

[Action]

 In the exhaust gas recirculation control valve according to the present invention, the auxiliary valve protruding from the control valve is always inserted into the hole of the valve seat with a predetermined gap even if the opening of the control valve varies, so that the exhaust gas is exhausted. The gas circulation rate can be kept constant.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an exhaust gas recirculation control valve according to the present invention. In the figure, the same parts as those in FIG. Reference numeral 23 is an improved control valve in the present invention, and FIG. 2 shows an enlarged view of the control valve 23 and the valve seat 13. Reference numeral 23a denotes a disc portion of the control valve 23, and an outer peripheral portion of the disc portion 23a abuts the inclined surface 13a of the valve seat 13 to perform a valve function. Reference numeral 23b is a cylindrical auxiliary valve that projects into the valve seat 13 from the center of the disc portion 23a, and is arranged with a predetermined gap from the vertical hole wall 13b of the valve seat 13.

Next, the operation will be described. The control valve 23 moves up and down by moving the shaft portion 14 up and down via the diaphragm 7, and as shown in FIG. 3, when the control valve 23 is opened, the gap between the disc portion 23a and the inclined surface 13a of the valve seat 13 is increased. By increasing the amount, the A characteristic of the characteristic diagram shown in FIG. 4 can be obtained. Here, since the auxiliary valve 23b is always inserted into the vertical hole wall 13b of the valve seat 13 with a predetermined gap in the opened state of the control valve 23, for example, the control valve 23 is attached to the diaphragm 7. Even if the generated negative pressure fluctuates up and down, the amount of exhaust gas passing through the valve seat 13 does not fluctuate and becomes constant, and the characteristic B of the characteristic diagram of FIG. 4 is obtained.

[0013]

[Effect of the device]

 As described above, according to the present invention, since the auxiliary valve is provided in a part of the control valve so as to project at a predetermined gap from the vertical hole wall of the valve seat, the opening of the control valve fluctuates due to variations in negative pressure. Even so, the exhaust gas recirculation amount can be kept constant, which makes it possible to obtain an inexpensive and highly reliable exhaust gas recirculation control valve without using a special device for keeping the negative pressure constant.

[Brief description of drawings]

FIG. 1 is a sectional view of an exhaust gas recirculation control valve according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a control valve and a valve seat of the exhaust gas recirculation control valve according to the present invention.

3 is a cross-sectional view of the control valve of FIG. 2 in an open state.

FIG. 4 is a characteristic diagram of an exhaust gas recirculation control valve according to the present invention.

FIG. 5 is a sectional view of a conventional exhaust gas recirculation control valve.

FIG. 6 is an enlarged cross-sectional view of a conventional control valve and valve seat.

FIG. 7 is a characteristic diagram of a conventional exhaust gas recirculation control valve.

FIG. 8 is a schematic diagram of a conventional exhaust gas recirculation system.

[Explanation of symbols]

 5 Exhaust gas recirculation control valve 7 Diaphragm 9 Exhaust gas passage 10 Housing 13 Valve seat 13a Inclined surface 13b Vertical hole wall 14 Shaft part 15 Bearing part 16 Holder 17,18 Holding plate 20 Case 21 Spring 23 Control valve 23a Disc part 23b Auxiliary valve

Claims (1)

[Claims for utility model registration] Claims: 1. A housing having an exhaust gas passage therein, and an amount of exhaust gas circulated from the exhaust pipe of the engine provided in the housing to the intake pipe through the exhaust gas passage. A control valve for adjusting the control valve, a valve seat with which the control valve abuts, and the exhaust gas passage is closed by the control valve; Supported on the shaft part and the lower part of the bearing part,
A holder for preventing invasion of carbon or the like in the exhaust gas to the bearing portion side, a diaphragm attached to an end portion of the shaft portion for opening and closing the control valve by a differential pressure, and a differential pressure is formed on the diaphragm. In an exhaust gas recirculation control valve having a case, an exhaust gas recirculation characterized in that a part of the control valve is provided with an auxiliary valve that slides with a vertical hole wall of a valve seat at a predetermined gap. Control valve.