JP2016133207A - Flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow control valve having no necessity of separately assembling bearings for a valve stem and improving at least durability of a bearing.SOLUTION: An EGR valve 1 comprises a housing 3 having a flow channel 2, a valve seat 4 provided in the flow channel 2, a valve element 5 capable of seating on the valve seat 4, a valve stem 6 provided integrally with the valve element 5 for moving the valve element 5 to the valve seat 4, an actuator 7 causing the valve stem 6 along with the valve element 5 to make a stroke motion, and a thrust bearing 8 provided between the housing 3 and the valve stem 6 and supporting the valve stem 6 in a manner of allowing a stroke motion. The thrust bearing 8 and the valve seat 4 are formed of an aluminium-based alloy integrally with the housing 3, and on at least the surfaces of parts of the thrust bearing 8 and the valve seat 4 in the housing 3, a ceramic coating having corrosion resistance, heat resistance and wear resistance is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flow control valve used to control a fluid flow rate in a fluid passage.

  Conventionally, as this type of technology, for example, an EGR valve described in Patent Document 1 below is known. As shown in a sectional view in FIG. 3, a valve seat 54 is provided in the housing 53 of the EGR valve. In order to open and close the valve body 55 with the valve seat 54, a valve shaft 56 having the valve body 55 fixed to one end is provided so as to be able to reciprocate (stroke) by an actuator 57. The valve shaft 56 is supported by two thrust bearings 57 and 58 provided in the housing 53 so as to be capable of stroke movement. In addition, a seal member 59 and a deposit guard 60 are provided between the valve shaft 56 and the housing 53. These members 59 and 60 prevent gas, foreign matter, moisture and the like from leaking from the gap between the valve shaft 56 and the thrust bearing 58 to the actuator 57 side.

JP 2013-7266 A

  However, in the EGR valve described in Patent Document 1, the thrust bearings 57 and 58 are configured as separate parts from the housing 53. Further, in order to ensure the durability of the thrust bearings 57 and 58, they may be formed of an expensive sintered material. Furthermore, it takes time and labor to assemble the two thrust bearings 57 and 58 to the housing 53, and the number of parts of the EGR valve is increased by the amount of the thrust bearings 57 and 58. In addition, in this EGR valve, the valve seat 54 is composed of a separate part from the housing 53. Moreover, in order to ensure the durability of the valve seat 54, the valve seat 54 may be formed of an expensive sintered material. Further, it is necessary to assemble the valve seat 54 to the housing 53, and the number of parts of the EGR valve is increased by the amount of the valve seat 54.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flow control valve that does not require a separate bearing for the valve shaft and can improve the durability of the bearing. . Another object of the present invention is to provide a flow control valve capable of improving the durability of the valve seat without the need to separately assemble a valve seat in addition to the above object.

  In order to achieve the above object, an invention according to claim 1 includes a housing having a fluid flow path, a valve seat provided in the flow path, a valve body provided seatable on the valve seat, and a valve. A valve shaft provided integrally with the valve body for moving the body relative to the valve seat, drive means for moving the valve shaft in the axial direction together with the valve body, and between the housing and the valve shaft A flow control valve provided with a bearing for supporting the valve shaft so as to be capable of stroke movement, wherein the bearing is formed of an alloy mainly composed of aluminum integrally with the housing, and at least a portion of the bearing in the housing It is intended that a ceramic coating having at least corrosion resistance is formed on the surface of the film.

  According to the configuration of the above invention, since the bearing is formed of an alloy mainly composed of aluminum integrally with the housing, the number of parts of the flow control valve is reduced by the amount of the bearing. In addition, since the ceramic coating having at least corrosion resistance is formed on the surface of at least the bearing portion of the housing, the corrosion resistance of at least the bearing portion of the housing is increased.

  In order to achieve the above object, the invention according to claim 2 is the invention according to claim 1, wherein the valve seat is formed of an alloy containing aluminum as a main component integrally with the housing, and at least of the housing. It is intended that a ceramic coating having at least corrosion resistance is formed on the surfaces of the bearing and the valve seat.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, the valve seat is also formed of an alloy mainly composed of aluminum integrally with the housing, so that the valve seat is also a part of the flow control valve. Points are reduced. In addition, since the ceramic coating having at least corrosion resistance is formed on the surface of at least the bearing and valve seat portion of the housing, the corrosion resistance of at least the bearing and valve seat portion of the housing is increased.

  In order to achieve the above object, according to a third aspect of the present invention, in the first or second aspect of the present invention, the ceramic coating is a titanium dioxide film formed on the surface of aluminum by an electrolytic method, and has a corrosion resistance. In addition to this, it is intended to have heat resistance and wear resistance.

  According to the configuration of the invention, in addition to the action of the invention according to claim 1 or 2, the ceramic coating has heat resistance and wear resistance in addition to corrosion resistance. Increases the heat resistance and wear resistance of the valve seat.

  According to the first aspect of the present invention, the valve shaft can be supported so as to be capable of stroke movement, and it is not necessary to separately assemble a bearing for the valve shaft, and the durability of the bearing can be improved.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is not necessary to assemble the valve seat separately, and the durability of the valve seat can be improved.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the durability of the bearing or the bearing and the valve seat can be further improved.

The front sectional view showing an EGR valve of a fully closed state concerning one embodiment. 1 is an enlarged cross-sectional view showing a ceramic coating formed on a surface of a housing according to one embodiment. Sectional drawing which concerns on a prior art example and shows an EGR valve.

  Hereinafter, an embodiment in which a flow control valve of the present invention is embodied as an exhaust gas recirculation valve (EGR valve) will be described in detail with reference to the drawings.

  FIG. 1 is a front sectional view showing the EGR valve 1 in a fully closed state. The EGR valve 1 is provided in an EGR passage that returns a part of exhaust gas discharged from the engine to the intake passage as EGR gas, and is used to control the flow rate of the EGR gas as a fluid.

  As shown in FIG. 1, the EGR valve 1 has a poppet valve structure, a metal housing 3 having an EGR gas flow path 2, a valve seat 4 provided in the middle of the flow path 2, and a valve seat 4 And a metal valve shaft 6 provided integrally with the valve body 5 in order to reciprocate (stroke) the valve body 5 with respect to the valve seat 4. And an actuator 7 for moving the valve shaft 6 in the axial direction together with the valve body 5. The actuator 7 corresponds to an example of the driving unit of the present invention. The actuator 7 is composed of a step motor as an example, and is configured to move the valve shaft 6 along with the valve body 5 in the axial direction. In the EGR valve 1, the valve element 5 is moved with respect to the valve seat 4 by the actuator 7 to change the opening area of the measuring part formed between the four and the five. Thereby, the EGR gas flow rate in the flow path 2 is controlled. In this embodiment, detailed description of the configuration of the actuator 7 is omitted. Both ends of the flow path 2 are an inlet 2a through which EGR gas is introduced and an outlet 2b through which EGR gas is led out.

  In this embodiment, the valve shaft 6 is disposed vertically through the housing 3 in FIG. 1, and a base end portion (upper end portion) of the valve shaft 6 is drivingly connected by an actuator 7 via a screw mechanism. The valve shaft 6 is formed of, for example, a copper sintered material. The valve seat 4 is formed integrally with the housing 3 and includes a valve hole 4a at the center thereof. The valve body 5 includes a shaft hole 5a at the center thereof, has a substantially conical shape, and includes a bottom surface 5b. The valve body 5 is fixed to the valve shaft 6 by welding 21 in a state where the tip end portion (lower end portion) of the valve shaft 6 is inserted into the shaft hole 5a. The valve body 5 is formed by SUS etc., for example. A thrust bearing 8 is provided between the housing 3 and an intermediate portion of the valve shaft 6 to support the valve shaft 6 so as to be capable of stroke movement. The thrust bearing 8 is configured by a hole formed in the center of the housing 3. The upper portion of the valve shaft 6 is provided with a deformed portion 9 whose cross section (cross section in a direction perpendicular to the axis of the valve shaft 6) has an oval shape. The cross-sectional shape of the hole of the thrust bearing 8 also has an oval shape that matches the deformed portion 9. Due to the engagement between the oval shaped deformed portion 9 and the thrust bearing 8, the valve shaft 6 is supported so as to be capable of stroke movement while being prevented from rotating. In addition, the housing 3 is provided with a lip seal 10 that seals between the housing 3 and the valve shaft 6 adjacent to the thrust bearing 8. The housing 3 is provided with a deposit guard plug 11 that guards the deposit between the housing 3 and the valve shaft 6 from the deposit, adjacent to the lip seal 10.

  In this embodiment, the thrust bearing 8 and the valve seat 4 are formed integrally with the housing 3. The housing 3 is formed of, for example, an alloy mainly composed of aluminum. Further, a ceramic coating is formed on the entire surface of the housing 3 including the thrust bearing 8 portion and the valve seat 4 portion. FIG. 2 is an enlarged cross-sectional view showing the ceramic coating 31 formed on the surface of the housing 3. The ceramic coating 31 is a titanium dioxide film formed by electrolytic method on the surface of the housing 3 made of aluminum, and has corrosion resistance, heat resistance and wear resistance. The ceramic coating 31 has a thickness of about “8 to 10 μm”, for example. As a method of forming the ceramic coating 31, for example, Henkel Japan's plasma electrolytic coating technology “electro-ceramic coating (ECC)” can be used.

  According to the EGR valve 1 of this embodiment described above, since the thrust bearing 8 is formed of an alloy containing aluminum as a main component integrally with the housing 3, the number of parts of the EGR valve 1 is reduced by the amount of the thrust bearing 8. . Further, since the ceramic coating 31 having corrosion resistance is formed on the surface of the housing 3 including the thrust bearing 8 portion, the corrosion resistance of the housing 3 including the thrust bearing 8 portion is increased. For this reason, the valve shaft 6 can be supported so as to be capable of stroke movement, and it is not necessary to separately install the thrust bearing 8 for the valve shaft 6, and the durability of the housing 3 including the thrust bearing 8 can be improved.

  In this embodiment, since the valve seat 4 is also formed of an alloy mainly composed of aluminum integrally with the housing 3, the number of parts of the EGR valve 1 is further reduced by the amount of the valve seat 4. Further, since the ceramic coating 31 having corrosion resistance is formed on the surface of the housing 3 including the valve seat 4 portion, the corrosion resistance of the valve seat 4 portion is also increased. For this reason, it is not necessary to assemble the valve seat 4 separately, and the durability of the valve seat 4 can be improved.

  In this embodiment, since the ceramic coating 31 has heat resistance and wear resistance in addition to corrosion resistance, the heat resistance and wear resistance of the housing 3 including the thrust bearing 8 and the valve seat 4 are increased. For this reason, the durability of the housing 3 including the thrust bearing 8 and the valve seat 4 can be further improved.

  In addition, this invention is not limited to the said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.

  (1) In the above embodiment, both the thrust bearing 8 and the valve seat 4 are formed of an alloy containing aluminum as a main component integrally with the housing 3, but only the bearing is formed of an alloy containing aluminum as a main component integrally with the housing. It can also be formed.

  (2) In the above embodiment, the ceramic coating 31 is formed on the surface of the housing 3 including the thrust bearing 8 and the valve seat 4, but the ceramic coating may be formed on the surface of the housing including the bearing portion. The ceramic coating can be formed only on the surface of the bearing and the valve seat, or the ceramic coating can be formed only on the surface of the bearing in the housing.

  (3) In the above embodiment, the ceramic coating 31 having corrosion resistance, heat resistance and wear resistance is formed on the surface of the housing 3, but a ceramic coating having only corrosion resistance and heat resistance or corrosion resistance is formed on the surface of the housing. You can also.

  The present invention can be used for an EGR valve that controls the flow rate of an EGR gas in an EGR passage, and a poppet valve structure that controls the flow rate of gas or liquid.

1 EGR valve (flow control valve)
2 Flow path 3 Housing 4 Valve seat 5 Valve body 6 Valve shaft 7 Actuator (drive means)
8 Thrust bearing 31 Ceramic coating

Claims (3)

A housing having a fluid flow path;
A valve seat provided in the flow path;
A valve body provided to be seated on the valve seat;
A valve shaft provided integrally with the valve body to move the valve body relative to the valve seat;
Drive means for moving the valve shaft in an axial direction together with the valve body;
In the flow control valve provided between the housing and the valve shaft, and comprising a bearing for supporting the valve shaft so as to be capable of stroke movement,
The bearing is formed of an alloy containing aluminum as a main component integrally with the housing, and a ceramic coating having at least corrosion resistance is formed on at least a surface of the bearing portion of the housing. valve.   Further, the valve seat is formed of an alloy mainly composed of aluminum integrally with the housing, and a ceramic coating having at least corrosion resistance is formed on a surface of at least the bearing and the valve seat portion of the housing. The flow control valve according to claim 1.   The flow rate according to claim 1 or 2, wherein the ceramic coating is a titanium dioxide film formed on the surface of the aluminum by an electrolytic method, and has heat resistance and wear resistance in addition to the corrosion resistance. Control valve.

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