JP2007127129A - Exhaust gas recirculation valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation valve in which clearance is not formed between a valve and a valve seat in closing the valve, caused by variation in machining accuracy or assembly accuracy of components such as a valve and a valve seat. <P>SOLUTION: When a valve shaft 30 is attached to a valve housing 21, an adjusting mechanism 71 can adjust to make the first valve 31 be abutted with the first valve seat 28 to be closed and to make the second valve 32 be abutted with the second valve seat 29 to be closed, by displacement or deformation of the valve seats 28, 29 and/or the valves 31, 32. Therefore, even if the machining accuracy or assembly accuracy of the components of the exhaust gas recirculation valve is varied, the adjusting mechanism 71 absorbs the variation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation valve disposed in an exhaust gas recirculation path for returning the exhaust gas of the engine to a combustion chamber of the engine in an internal combustion engine such as a diesel engine or a gasoline engine.

  FIG. 1 is a cross-sectional view showing a configuration of an EGR valve (exhaust gas recirculation valve) disclosed in Patent Document 1, for example. In the figure, 1 is a valve housing (valve body), 1a is a first port through which exhaust gas of the engine flows, 1b is a second port through which the exhaust gas flows, 1c is the first and second ports 1a. , 1b, a third port for letting out the exhaust gas flowing in, 2 is a valve shaft, 3 and 4 are two valves fixed or integrally formed with the valve shaft 2, 5 is a diaphragm connected to the valve shaft 2, 6 Is a set spring that presses the diaphragm 5 toward the valve shaft 2 (in the valve closing direction), 7 is a negative pressure source, 19 is a diaphragm chamber for introducing negative pressure from the negative pressure source 7, and 20a is press-fitted into the valve housing 1. The valve seat 20b that is fixed by, for example, contacting one valve 3 is fixed to the valve housing 1 by press fitting or the like, and the other valve 4 A valve seat to abut.

Next, the operation will be described.
In the closed state where the two valves 3 and 4 are seated on the respective valve seats 20a and 20b, when a negative pressure acts on the diaphragm 5, the two valves 3 and 4 move up together with the valve shaft 2, and the first and first valves The 2 ports 1a and 1b are in a valve open state in communication with the third port 1c. In this valve open state, exhaust gas from the engine flows into the valve housing 1 from the first and second ports 1a and 1b and flows out from the third port 1c, thereby passing through the intake passage. Re-enters the engine combustion chamber. As a result, combustion is suppressed by the amount of non-combustible exhaust gas mixed in the combustion chamber of the engine, so that even during lean burn operation where the mixing ratio of fuel to air is low, the combustion gas and the it is possible to suppress the increase in the engine temperature, the nitrogen oxides with the problems and once was elevated combustion gas and the engine temperature during the lean burn operation increases in (NO _X) can be suppressed.

Japanese Patent Laid-Open No. 6-147025

  However, since the conventional exhaust gas recirculation valve is configured as described above, there are the following problems. That is, the valve seats 20a and 20b are fixed to the valve housing 1 by press-fitting or the like. However, the processing accuracy of the valve seat and the dimensions when the valve seat is fixed are likely to vary. A gap is created between the valve and the valve seat, resulting in the exhaust gas leaking. Further, due to the action of the high-temperature and high-pressure exhaust gas, the valve housing 1, the valve shaft 2 and the valves 3 and 4 are heated and thermally expanded at the exhaust gas temperature. If they are different, in this case as well, a gap is formed between the valve and the valve seat, and the exhaust gas leaks. Thus, when the exhaust gas leaks, for example, when the engine is idling, there is a problem in that idling rotation is extremely reduced and idling becomes unstable.

  The present invention has been made to solve the above-described problems. A gap between the valve and the valve seat when the valve is closed due to variations in processing accuracy and assembly accuracy of parts such as the valve and the valve seat. An object of the present invention is to obtain an exhaust gas recirculation valve in which no generation occurs.

  In addition, the present invention inevitably absorbs variations in processing accuracy and assembly accuracy of parts such as valves and valve seats, and the gap between the valve and the valve seat when the valve is closed due to the variations. An object of the present invention is to obtain an exhaust gas recirculation valve in which the valve at the valve closing position does not open due to thermal expansion of components due to a high exhaust gas temperature.

  Furthermore, the present invention can easily eliminate the gap when the exhaust gas recirculation valve is assembled, when a gap is generated between the valve in the closed position and the valve seat due to variations in processing accuracy and assembly accuracy of parts. An object of the present invention is to obtain an exhaust gas recirculation valve.

  It is another object of the present invention to provide an exhaust gas recirculation valve that can absorb a gap generated between a valve at a valve closing position and a valve seat by the valve seat itself due to variations in processing accuracy and assembly accuracy of parts. And Another object of the present invention is to provide an exhaust gas recirculation valve that can absorb a gap generated between a valve in a valve-closed position and a valve seat due to variations in processing accuracy and assembly accuracy of the parts. To do.

  Further, according to the present invention, for example, even if the thermal expansion coefficients of the valve housing and the valve shaft are different, the valve in the closed position is not opened by the thermal expansion of the valve housing and the valve shaft due to the high exhaust gas temperature. The object is to obtain an exhaust gas recirculation valve.

  An exhaust gas recirculation valve according to the present invention has an exhaust gas inlet and an outlet that can be connected to an exhaust gas recirculation path of an engine, and includes a primary flow path on the inlet side and the primary flow A valve housing forming a secondary flow path that branches off from the path, and first and second flow path openings formed in the branch communication portion of the primary flow path and the secondary flow path; The first and second valve seats provided in the first and second flow path openings, the valve shaft attached to the valve housing so as to be movable in the axial direction, and attached to the valve shaft, In the exhaust gas recirculation valve comprising first and second valves that contact and close the first and second valve seats when the valve shaft moves in one direction, the second fixed to the valve shaft The valve is the second valve The first valve of the valve shaft is closed so that the first valve contacts and closes the first valve seat in an operating temperature range after the valve is contacted and closed. A gap is set between the flange portion and the flange portion provided in the vicinity of the mounting position, and is press-fitted and fixed to the valve shaft.

  According to such an exhaust gas recirculation valve, at the time of assembly of the exhaust gas recirculation valve, the second valve fixed to the valve shaft is brought into contact with and closed to the second valve seat, and then in the operating temperature range, By setting a gap between the first valve and a flange portion protruding in the vicinity of the first valve mounting position of the valve shaft, and press-fitting and fixing to the valve shaft, the first and second The mutual interval between the valve seats can be adjusted to be equal to the mutual interval between the first and second valves. For this reason, due to variations in processing accuracy and assembly accuracy of the valve seats, It is possible to prevent a gap from occurring between them. As a result, even if the coefficient of thermal expansion of each member is different or the same, the error of each member that occurs in the operating temperature range heated to high temperature by the exhaust gas is caused between the first valve and the flange portion. Since it absorbs in the provided gap, it is possible to prevent the occurrence of a gap between the valve and the valve seat, and it is possible to prevent inconvenience that idling rotation is reduced and idling becomes unstable during engine idling.

Embodiment 1 FIG.
2 is a cross-sectional view of an exhaust gas recirculation valve according to Embodiment 1 of the present invention. In the figure, 21 is a valve housing that can be connected to the exhaust gas recirculation path of the engine, 22 is an inflow port for introducing exhaust gas that the valve housing 21 has, 23 is an outflow port for exhaust gas recirculation that the valve housing 21 has, 24 is A primary-side flow path 25 formed in the valve housing 21 and a secondary-side flow path 25 also formed in the valve housing 21 are branched from the primary-side flow path 24. Then, they merge at the outlet 23.

  Reference numerals 26 and 27 denote first and second flow path openings for attaching a valve seat formed at a branch communication portion between the primary flow path 24 and the secondary flow path 25 in the valve housing 21; A first locking portion for locking a valve seat formed in a step shape at the upper end of one flow passage opening 26, 27a is a valve seat also formed in a step shape at the upper end of the second flow passage opening 27. A second locking portion for locking, 28 is a first valve seat that is press-fitted and fixed to the first flow path opening 26, and 29 is a second valve seat that is press-fitted and fixed to the second opening 27. The first and second valve seats 28 and 29 have tapered valve seat holes 28a and 29a whose lower end side gradually becomes smaller in diameter.

  30 is a valve shaft attached to the valve housing 21 so as to be movable in the axial direction, 30a is a columnar first valve insertion portion formed near the lower end of the valve shaft 30, and 30b is a first valve insertion portion 30a. A first valve stop portion (first collar portion) formed at the lower end, 30c is a cylindrical second valve insertion portion formed substantially in the middle of the valve shaft 30, and 30d is a lower end of the second valve insertion portion 30c. The first valve stop portion 30b and the second valve stop portion 30d are larger in diameter than the first valve insertion portion 30a and the second valve insertion portion 30c. Is formed.

31 is a first valve fitted to the first valve insertion portion 30a of the valve shaft 30 so as to be slidable in the axial direction, and 32 is fitted to a second valve insertion portion 30c of the valve shaft 30 to be second valve stop portion. This is the second valve abutted and fixed to 30d.
Reference numeral 33 denotes a component assembly port provided in the valve housing 21. The component assembly port 33 is a valve shaft on which the first and second valve seats 28 and 29 and the first and second valves 31 and 32 are assembled. 30 is formed in a diameter that can be assembled in the valve housing 21.

  34 is a closing member for closing the component assembly port 33, 35 is a tightening screw for the closing member 34, and 36 is interposed between the first valve stop 30 b of the valve shaft 30 and the lower surface of the first valve 31. The elastic member 36 is composed of a leaf spring or the like, and is in a direction in which the first valve 31 slidable in the axial direction of the valve shaft 30 as described above is brought into contact with the first valve seat 28. Energized.

  Reference numeral 37 denotes a bush attached to the upper portion of the valve housing 30, and 38 denotes a filter fixed to the lower end of the bush 37. The valve shaft 30 penetrates through the central hole portion of the bush 37 and the filter 38 so as to be movable in the axial direction. is doing.

  39 is a spring seat connected to the upper end of the valve shaft 30; 40 is a spacer fixed to the upper end of the valve housing 30; 41 is a stepping motor attached to the valve housing 30 via the spacer 40; A tightening screw that fastens and fixes the stepping motor 41 to the valve housing 30; 44, a motor shaft that moves up and down; 45, a spring seat connected to the lower end of the motor shaft 44; 46, upper ends of the valve housing 30 and the valve shaft 30; Reference numeral 47 denotes a compression spring interposed between the spring receiving seat 39 and the compression spring 47 interposed between the stepping motor 41 and the spring receiving seat 45 at the lower end of the motor shaft 44.

  According to the exhaust gas recirculation valve of the first embodiment described above, the first valve 31 that is slidable with respect to the valve shaft 30 is the first valve by the elastic force of the elastic member 36 such as a leaf spring. Since the valve 28 is always energized in the valve closing direction in contact with the seat 28, the first and second valve seats 28, 29, the first and second valves 31, 32, etc. Even if there are variations in the processing accuracy and assembly accuracy of parts, the first valve 31, the first valve seat 28, and the second valve are moved by the displacement of the first valve 31 due to the elastic force of the elastic member 36. 32 and the second valve seat 29 can be assembled so as to contact and close. When the assembled exhaust gas recirculation valve is used, the high temperature exhaust gas passing through the inside of the valve housing 21 heats the valve housing 21 and the valve shaft 30 and the like to cause thermal expansion. In this case, Even if the first valve 31 in the valve closing position tries to open due to the difference in the coefficient of thermal expansion of the valve shaft 30, the valve 31 is maintained in the valve closing position by the elastic force of the elastic member 36.

  Therefore, according to the first embodiment, the elastic member 36 serves as an adjustment mechanism that contacts and closes both the first valve 31 and the first valve shaft 28 and the second valve 32 and the second valve shaft 29. Due to the function, it occurs between the valve and the valve seat when the valve is closed due to variations in the processing accuracy and assembly accuracy of parts such as the valve and valve seat, and the difference in thermal expansion coefficient between the valve shaft and valve housing. A gap can be prevented and the valve closing accuracy can be improved.

Embodiment 2. FIG.
FIG. 3 is a sectional view of an exhaust gas recirculation valve according to Embodiment 2 of the present invention. In the drawing, 51 is a valve seat press-fitting amount adjustment gap provided between the first locking portion 26 a at the upper end of the first flow path opening 26 of the valve housing 30 and the first valve seat 28. .
That is, in the second embodiment, when the exhaust gas recirculation valve is assembled, the interval between the two valves 31 and 32 on the valve shaft 30 is equal to the interval between the two valve seats 28 and 29. The gap 51 is provided in advance so that the press-fitting amount of the first valve seat 28 to one flow path opening 26 can be adjusted.

  Therefore, according to the second embodiment, when the exhaust gas recirculation valve is assembled, as described above, the interval between the two valves 31 and 32 and the interval between the two valve seats 28 and 29 are equal. By setting the gap 51 of a length that can adjust the press-fitting amount of the first valve seat 28 to the first flow path opening 26, the length of the gap 51 by adjusting the press-fitting amount of the first valve seat 28 is set. Variations in the processing accuracy of valves and valve seats can be absorbed. Therefore, the valve seat can be assembled so that no gap is generated between the valve and the valve seat when the valve is closed after assembly.

Embodiment 3 FIG.
4 is a sectional view of an exhaust gas recirculation valve according to Embodiment 3 of the present invention. In the same figure, 28b is an elastically deformable deformable piece (deformable portion) formed at the lower end opening edge which becomes the small diameter opening end of the valve seat hole 28a having a taper of the first valve seat 28. The deformable piece 28b extends downward along the tapered surface of the valve seat hole 28a.
That is, in the third embodiment, when the exhaust gas recirculation valve is assembled, the deformable piece 28b of the first valve seat 28 is elastically deformed to be brought into pressure contact with the first valve 31.

  As described above, the deformable piece 28b of the first valve seat 28 is brought into pressure contact with the first valve 31, so that the assembly accuracy or component accuracy (processing accuracy) of the first valve seat 28 and the first valve 31 is achieved. ) Can be absorbed by the deformable piece 28b of the first valve seat 28 itself. For this reason, it is possible to prevent a gap from being generated between the valve seat 28 and the valve 31 due to variations in the assembly accuracy or component accuracy.

Embodiment 4 FIG.
FIG. 5 is a sectional view of an exhaust gas recirculation valve according to Embodiment 4 of the present invention. In the figure, reference numeral 61 denotes a valve seat mounting case that is press-fitted and fixed in the valve housing 21. The case 61 is made of a material having the same thermal expansion coefficient as that of the valve shaft 30 and is formed in a cylindrical shape having upper and lower ends opened. ing. The second valve seat 29 is press-fitted and fixed to the upper end opening of the case 61, and the first valve seat 28 is press-fitted and fixed to the lower end opening of the case 61. Reference numeral 61 a denotes a connection opening provided in the case 61 and connected to the primary flow path 24 of the valve housing 21.

  According to the fourth embodiment, since the case 61 separate from the valve housing 21 is employed as the valve seat mounting member, the case 61 can be formed of a material having the same thermal expansion coefficient as the valve shaft 30 as described above. . In this way, by making the thermal expansion of the case 61 and the valve shaft 30 equal, the case 61 and the valve shaft 30 are made of high-temperature and high-pressure exhaust gas flowing into the case 61 from the primary flow path 24 of the valve housing 21. Even if heated and expanded, there is no gap between the case 61 and the valve seats 28 and 29, that is, in the attachment portions of the valve seats 28 and 29. For this reason, exhaust gas does not leak from the attachment portions of the valve seats 28 and 29.

Embodiment 5. FIG.
6 is a cross-sectional view of an exhaust gas recirculation valve according to Embodiment 5 of the present invention. In the fifth embodiment, each of the first and second valves 31 and 32 is formed of a thin plate such as stainless steel, and these valves 31 and 32 are connected to the first and second valve seats 28 and 29. In order to make them come into contact with each other, they are plastically deformed during assembly.
That is, according to the fifth embodiment, for example, when the valve shaft 30 is assembled to the valve housing 21, by applying axial pressure to the valve shaft 30, both the valves 31 and 32 are connected to the respective valve seats. It can be deformed by abutting against 28 and 29.

  As described above, by plastically deforming the first and second valves 31 and 32, a gap generated between the valve seat and the valve due to variations in processing accuracy and assembly accuracy of the valve seat and the valve. Can be prevented.

Embodiment 6 FIG.
FIG. 7 is a cross-sectional view of an exhaust gas recirculation valve according to Embodiment 6 of the present invention. In the figure, reference numeral 71 denotes a gap for adjusting the valve press-fit amount provided between the first valve 31 press-fitted into the first valve insertion portion 30a of the valve shaft 30 and the first valve stop 30b of the valve shaft 30. , 72 are welded portions between the first valve insertion portion 30 a and the first valve 31.

  That is, in the above-described second embodiment, the clearance 51 for adjusting the valve seat press-fit amount is provided between the first locking portion 26a and the first valve seat 28 in the first flow path opening 26 of the valve housing 21. In the sixth embodiment, the gap 71 is provided on the valve shaft 30 side so that the press-fitting amount of the first valve 31 with respect to the first valve insertion portion 30a of the valve shaft 30 can be adjusted. When the first valve 31 is press-fitted to the valve shaft 30, after adjusting the press-fitting amount of the valve 31 to the valve shaft 30 so that the valve 31 is pressed into contact with the first valve seat 28 without a gap, the valve 31 is moved to the valve shaft. 30 to be welded.

  According to the sixth embodiment, when the first valve 31 is press-fitted into the valve shaft 30, welding is performed after adjusting the press-fitting amount of the valve 31 as described above. It is possible to prevent a gap from being generated between the valve seat and the valve due to variations in accuracy. Further, even when the thermal expansion coefficients of the respective members are different or the same, errors of the respective members occurring in the use temperature range heated to high temperature by the exhaust gas are caused by the first valve and the first valve stop portion (the first valve stop portion). The gap between the valve and the valve seat can be prevented, and the idling rotation is reduced and the idling becomes unstable when the engine is idling. Can be avoided.

Next, the assembly of the exhaust gas recirculation valve according to each embodiment of the present invention will be described.
FIG. 8A is an exploded view in which the valve shaft and two valves of the exhaust gas recirculation valve according to the first to sixth embodiments of the present invention are disassembled in relation to one valve seat, and FIG. It is an assembly drawing of Fig.8 (a).
In FIG. 8A, 31 a is the center hole of the first valve 31, and 32 a is the center hole of the second valve 32.

  In assembling the valve shaft 30 of the exhaust gas recirculation valve according to the first embodiment and the first and second valves 31 and 32, first, the elastic member 36 (not shown in FIG. 8) in FIG. 30, the valve shaft 30 is passed through the center hole 31 a of the first valve 31, and the first valve 31 is axially inserted into the first valve insertion portion 30 a of the valve shaft 30. The elastic member 36 is sandwiched between the valve 31 and the first valve stop 30b.

  Next, after the first valve seat 28 is fitted into the valve shaft 30, the valve shaft 30 is passed through the central hole 32 a of the second valve 32, and the second valve 32 is inserted into the second valve insertion portion 30 c of the valve shaft 30. The center hole 32a is press-fitted and the valve 32 is brought into contact with and engaged with the second valve stop 30d. In this state, the second valve 32 is fixed to the valve shaft 30 by caulking a portion of the second valve insertion portion 30c opposite to the second valve stop portion 30d. In this way, the elastic member 36 is attached to the valve shaft 30, and the first valve 31 is fitted and set so as to be slidable in the axial direction, and the second valve 32 is press-fitted and fixed. The first valve seat 28 is unitized between the first and second valves 31 and 32.

  In assembling the valve shaft 30 of the exhaust gas recirculation valve according to the second to fourth embodiments and the first and second valves 31 and 32, first, the valve shaft 30 is inserted into the central hole 31a of the first valve 31. The center hole 31a of the first valve 31 is press-fitted into the first valve insertion portion 30a of the valve shaft 30, and the valve 31 is brought into contact with the first valve stop portion 30b of the valve shaft 30. Combine. In this state, the first valve 20 is fixed to the valve shaft 30 by caulking the first valve insertion portion 30a at a portion opposite to the first valve stop portion 30b.

  Next, after the first valve seat 29 is fitted into the valve shaft 30, the valve shaft 30 is passed through the central hole 32 a of the second valve 32, and the second valve 32 is inserted into the second valve insertion portion 30 c of the valve shaft 30. The center hole 32a is press-fitted and the valve 32 is brought into contact with and engaged with the second valve stop 30d. In this state, the second valve 32 is fixed to the valve shaft 30 by caulking the second valve insertion portion 30c at a portion opposite to the second valve stop portion 30d. In this way, as shown in FIG. 8B, the first and second valves 31 and 32 are press-fitted and fixed to the valve shaft 30, respectively, and the second valve is interposed between the valves 31 and 32. The seat 29 is unitized with the valve shaft 30.

Although the first and second valves 31 and 32 of the exhaust gas recirculation valve according to the fifth embodiment have different shapes, the valve shaft 30 and the second valve 31 and the second valve 31 and 32 are assembled in the same assembly process as in the second to fourth embodiments. Assembly with the first and second valves 31, 32 can be performed.
When assembling the valve shaft 30 and the first and second valves 31 and 32 of the exhaust gas recirculation valve in FIG. 7 according to the sixth embodiment, the same procedure as in the second to fourth embodiments described above is used. Only the second valve 32 is press-fitted and fixed to the second valve insertion portion 30c of the valve shaft 30, and the assembly of the first valve 31 will be described later.

As described above, the valves 31 and 32 assembled to the valve shaft 30 are assembled to the valve housing 21 in the steps shown in FIGS.
FIGS. 9A, 9B, 10A, 10B, and 10C are assembly process diagrams applied to explain the assembly process of the exhaust gas recirculation valve according to each embodiment of the present invention.

  When assembling the exhaust gas recirculation valve according to the first embodiment, first, the filter 38 with the holder 38a, the bush 37, and the washer 43 are sequentially fitted into the valve shaft through-hole provided in the upper portion of the valve housing 21 and caulked. Keep it. In this state, the second valve seat 29 is press-fitted and fitted into the second opening 27 in the valve housing 21 from the component assembly port 33 until it abuts against the second locking portion 27a. The second valve seat 29 is fixed to the valve housing 21 by caulking the lower end side of the second valve seat 29 in the second flow path opening 27 in this state (see FIG. 9B). This process is applicable to the exhaust gas recirculation valve of all the embodiments except the case of the fourth embodiment (FIG. 5), and the assembly in the fourth embodiment will be described later.

  Next, the valve shaft 30 in which the first and second valves 31 and 32 and the first valve seat 28 are assembled as described above is transferred from the component assembly port 33 of the valve housing 21 to the second valve seat 29. The upper end side of the valve shaft 30 is inserted into the filter 38, and the first valve seat 28 is press-fitted into the first flow path opening 26 until it abuts on the first locking portion 26a. The valve seat 28 is fixed to the valve housing 21 by caulking the lower end side of the first valve seat 28 in the opening 26 (see FIG. 10A).

  After the fixing, the valve shaft 30 is further pushed in so that the second valve 32 comes into contact with the second valve seat 29 and the first valve 31 comes into contact with the first valve seat 28 and protrudes from the bush 37. A spring seat 39 is attached to the upper end of the valve shaft 30, and a compression spring 46 is interposed between the spring seat 39 and the valve housing 21 (see FIG. 10B). Finally, the component assembly port 33 of the valve housing 21 is closed with a closing member 34, and the closing member 34 is fastened and fixed to the valve housing 21 with a fastening screw 35 (see FIG. 10C), as shown in FIG. The exhaust gas recirculation valve according to the first embodiment is assembled by assembling the stepping motor 41 on the upper portion of the valve housing 21 via the spacer 40.

  In the exhaust gas recirculation valve according to Embodiment 1 assembled in this way, the first valve 31 can slide with respect to the valve shaft 30, and the valve 31 is attached in the valve closing direction by the elastic member 36. As a result, it is possible to prevent a gap between the valve and the valve seat due to variations in processing accuracy and assembly accuracy of the valve and the valve seat.

  In the case of the exhaust gas recirculation valve according to the second embodiment, as shown in FIG. 3, the first valve with respect to the second valve seat 29 press-fitted into the second flow path opening 27 and fixed by caulking. Since the mounting interval of the seat 28 can be adjusted to be longer than the interval between the first and second valves 31 and 32 by the clearance 51 for adjusting the valve seat press-fitting amount, the second valve 32 can be adjusted at the time of assembly. In the state in which the first valve seat 28 is correctly press-fitted and fitted into the second valve seat 29, the first valve seat 28 can be accurately pressed against the first valve seat 28 so that there is no gap between them. The press-fitting position can be adjusted. The assembly procedure is the same as in the first embodiment.

  The assembly procedure of the exhaust gas recirculation valve of FIG. 4 according to the third embodiment is exactly the same as that of the first embodiment, but the first valve seat 28 can be deformed in a reverse taper shape with respect to the first valve 31. It has the piece portion 28b, and at the time of assembly, the deformable piece portion 28b is pressed against the first valve 31 and is plastically deformed, so that a gap between the valve 31 and the valve seat 28 can be eliminated.

Next, assembly of the exhaust gas recirculation valve of FIG. 5 according to Embodiment 4 will be described.
First, as shown in FIG. 9A, after the case 61 is press-fitted and fixed from the component assembly port 33 into the valve housing 21 in which the filter 38 with the holder 38a, the bush 37, and the washer 43 are mounted, The second valve seat 29 is press-fitted into the upper end opening (corresponding to the second flow path opening 27) and fixed by caulking.

Next, the valve shaft 30 in which the first and second valves 31 and 32 and the first valve seat 28 are assembled is passed through the part assembly port 33 into the case 61 in the manner shown in FIG. After the upper end side is inserted into the filter 38, the first valve seat 28 on the valve shaft 30 is press-fitted into the lower end opening (corresponding to the first flow path opening 26) of the case 61 and fixed by caulking. Other assembly steps are the same as those in the first embodiment.
Thus, according to the assembled exhaust gas recirculation valve according to the fourth embodiment, the first and second valve seats 28 and 29 are press-fitted and fixed to the case 61 separate from the valve housing 21. The effect as described in Embodiment 4 can be obtained.

  The assembly process of the exhaust gas recirculation valve of FIG. 6 according to the fifth embodiment is performed when the second and first valves 32, 31 are pressed and matched with the second and first valve seats 29, 28. Only the point of plastic deformation is different from the case of the first embodiment, and other assembly steps are the same as those of the first embodiment.

  When assembling the exhaust gas recirculation valve of FIG. 7 according to the sixth embodiment, the second valve seat 29 is press-fitted into the second flow path opening 27 in the valve housing 21 in the steps shown in FIGS. In the state of caulking and fixing, the valve shaft 30 in which only the second valve 32 is press-fitted and caulked and fixed is passed from the component assembly port 33 to the second valve seat 29 in the valve housing 21, and the valve shaft 30 After the upper end side is inserted into the filter 38, the first valve seat 28 is press-fitted and fixed to the first flow path opening 26 in the valve housing 30. Next, the first valve 31 is fitted into the valve shaft 30, the valve 31 is fitted and pressed into the first valve seat 28, and the first valve 31 is welded to the valve shaft 30 in this state. Other assembly steps are the same as those in the first embodiment.

According to such an assembly method of the exhaust gas recirculation valve, the first valve 31 can be accurately press-fitted and aligned with the first valve seat 28 during the assembly, and a gap is generated between them. Can be prevented.
In order to prevent the valves 31 and 32 from coming off from the valve shaft 30, a retaining ring is fixed to the valve insertion portions 30a and 30c of the valve shaft 30 on the opposite side of the valve stopping portions 30b and 30d by welding or the like. You can do it.

  As described above, according to the exhaust gas recirculation valve of the present invention, exhaust gas recirculation can be controlled with high accuracy by being connected to the exhaust gas recirculation path of an engine such as a diesel turbo car.

It is sectional drawing which shows the conventional exhaust gas recirculation valve. 1 is a cross-sectional view of an exhaust gas recirculation valve according to Embodiment 1 of the present invention. It is sectional drawing of the exhaust-gas recirculation valve by Embodiment 2 of this invention. It is sectional drawing of the exhaust-gas recirculation valve by Embodiment 3 of this invention. It is sectional drawing of the exhaust-gas recirculation valve by Embodiment 4 of this invention. It is sectional drawing of the exhaust-gas recirculation valve by Embodiment 5 of this invention. It is sectional drawing of the exhaust-gas recirculation valve by Embodiment 6 of this invention. FIG. 8 (a) is an exploded view in which the valve shaft and two valves of the exhaust gas recirculation valve according to the first to sixth embodiments of the present invention are disassembled in relation to one valve seat, and FIG. 8 (b) is a diagram. It is an assembly drawing of 8 (a). It is an assembly process diagram applied to explain an assembly process of the exhaust gas recirculation valve according to each embodiment of the present invention. It is an assembly process diagram applied to explain an assembly process of the exhaust gas recirculation valve according to each embodiment of the present invention.

Explanation of symbols

  21 Valve housing, 22 Inlet for introducing exhaust gas, 23 Outlet for returning exhaust gas, 24 Primary flow path, 25 Secondary flow path, 26 First flow path opening, 26a First locking 27, second flow path opening, 27a second locking portion, 28 first valve seat, 29 second valve seat, 28a, 29a valve seat hole, 28b deformable piece, 30 valve shaft, 30a 1st valve insertion part, 30b 1st valve stop part (1st collar part), 30c 2nd valve insertion part, 30d 2nd valve stop part (2nd collar part), 31 1st valve, 32 2nd valve , 31a, 32a Central hole, 33 Parts assembly port, 34 Closure member, 35, 42 Clamping screw, 36 Elastic member, 37 Bush, 38 Filter, 38a Holder, 39, 45 Spring seat, 40 Spacer, 41 Stepping motor Motor, 43 a washer, 44 a motor shaft, 46 and 47 a compression spring, 51 a gap for adjusting the valve seat press-fitting amount, 61 cases, 61a connecting opening, 71 clearance for adjustment valve pressed amount, 72 weld.

Claims (1)

An exhaust gas inlet and an outlet that can be connected to an exhaust gas recirculation path of an engine, and a primary flow path on the inlet side and a secondary flow path branched from the primary flow path A forming valve housing;
First and second flow path openings formed in the branch communication portion of the primary flow path and the secondary flow path;
First and second valve seats provided in the first and second flow path openings;
A valve shaft attached to the valve housing so as to be axially movable;
An exhaust gas recirculation valve that is attached to the valve shaft and includes first and second valves that contact and close the first and second valve seats when the valve shaft moves in one direction.
After the second valve fixed to the valve shaft contacts and closes the second valve seat, the first valve contacts and closes the first valve seat in the operating temperature range. The first valve is press-fitted and fixed to the valve shaft by setting a gap between the valve shaft and a flange protruding in the vicinity of the mounting position of the first valve. Exhaust gas recirculation valve.

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