JP2011220141A - Electromagnetic secondary air control valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic secondary air control valve device that is free from any actuation failure, by preventing the entry of contaminations into an electromagnetic actuator, without affecting attraction force characteristics of the electromagnetic actuator.SOLUTION: The electromagnetic secondary air control valve device includes a dust seal 28 for preventing the entry of the contaminations into the electromagnetic actuator. The dust seal 28 includes a cylindrical seal 52 of two steps of a lip 54 and a shoulder 53. The lip 54 is brought into slide contact with an outer circumferential surface of a valve shaft 27 at an inner circumferential side of the lip. The shoulder 53 includes an abutment surface S closer to the outer circumferential side as compared with the lip 54 having a small diameter. The abutment surface S is pressed by a spring load to abut against a small-diameter locking part 50. A bead 55 is provided on the abutment surface S of the shoulder 53. The total amount in the height direction of the bead 55 is crushed to secure a prescribed surface pressure when pressed by the prescribed spring load so that the abutment surface S is reliably in close contact with the small-diameter locking part 50.

Description

  The present invention relates to an electromagnetic secondary air control valve for opening and closing a secondary air flow path for introducing secondary air pressure-fed and supplied from an air pump into a three-way catalytic converter, and to prevent foreign matter from entering the electromagnetic actuator. Related.

[Conventional technology]
Conventionally, when the engine is started, especially when the exhaust temperature of the exhaust gas of the engine is low, the secondary air generated by operating the air pump is led to a three-way catalytic converter that purifies the exhaust gas, and the three-way catalyst is Secondary air supply devices that are activated are known. An electromagnetic secondary air control valve is installed in the flow path of the secondary air for guiding the secondary air pressure-fed and supplied from the air pump to the three-way catalytic converter (see, for example, Patent Document 1).

  As shown in FIG. 4, an electromagnetic secondary air control valve 100 disclosed in Patent Document 1 includes an electromagnetic valve 103 that opens and closes a flow path of secondary air, and engine exhaust gas flows backward to the electromagnetic valve side. And a check valve 102 having a reed valve structure that opens and closes in response to a pressure difference. The electromagnetic valve 103 includes a valve body 119 that opens and closes an opening (valve hole) 118 provided in the middle of the flow path of the secondary air, and an electromagnetic actuator 120 that drives the valve body 119 in the valve opening direction. Has been.

  The electromagnetic actuator 120 accommodates the plunger 129 and the plunger 129 so as to be able to reciprocate, and urges the plunger 129 in the valve closing direction, and a stator core 132 that forms a suction portion that generates a suction force generated by the magnetic force of the solenoid coil 133. It is a well-known one comprising a coil spring 121 or the like. A shaft 127 that is integrally coupled to the valve body 119 is fitted into the shaft center of the plunger 129 and fixed by caulking to constitute a poppet type valve. Further, the stator core 132 is provided at the suction portion side end on the same axis as the shaft 127, and the gap between the stator core 132 and the shaft 127 is sealed, so that foreign matter can enter the stator core 132. A dust seal 128 is provided for prevention.

[Problems with conventional technology]
However, although the air pump is activated by a control signal from an engine control device (hereinafter referred to as ECU), a rise delay or a pressure rise delay occurs, and when this and the occurrence of exhaust pulsation of the engine overlap, The pressure balance of the check valve 102 may be transiently disrupted, and exhaust gas backflow may occur temporarily. The exhaust gas flowing backward includes foreign matters such as deposits and condensed water. The deposit may contain not only carbon particles having a relatively large particle size but also metal powder or inorganic particles.

  At this time, the exhaust gas flowing backward flows along the shaft 127 from the gap between the valve element 119 and the valve hole 118 of the poppet type valve which has started to open, as indicated by the dotted arrow in FIG. The cylindrical seal portion 152 of the dust seal 128 that seals the outer peripheral surface of the dust seal 128. Therefore, there is a possibility that deposits and condensed water contained in the exhaust gas ride on the airflow that flows backward, collide with the cylindrical seal portion 152 of the dust seal 128, and partly adhere and accumulate over time. Further, there is a possibility that the remainder reaches the metal ring portion 151 further downstream, adheres to the ring portion 151, and accumulates.

  In the conventional dust seal 128, a metal ring portion 151 and a rubber cylindrical seal portion 152 are integrated by baking, and the rubber cylindrical seal portion 152 is always shaft 127 by the elastic force of rubber. A seal pressure is generated on the outer peripheral surface of the sealant to provide a good seal. The metal annular portion 151 is sandwiched between the pressure plate 130 for guiding the coil spring 121 and the inner locking portion 148 of the stator core 132 in a metal touch state, and is pressed by the spring load to be locked inward. It is locked to the portion 148. Locking in the metal touch state without using an elastic body causes the locking portion of the inner locking portion 148 to sink or float due to fluctuations in the spring load, affecting the predetermined attractive force characteristics of the electromagnetic actuator 120. This is because there is not. Therefore, since the annular portion 151 is locked to the inner locking portion 148 only by pressing the spring load in the metal touch state, a sufficient seal may not be ensured.

  Therefore, a part of the backflow of the exhaust gas may enter from the locking portion in the metal touch state. Then, when deposits or moisture contained in the exhaust gas flowing backward enters the stator core 132, rusting due to moisture occurs in the stator core 132, and deposits deposit and accumulate over time, increasing the sliding resistance of the electromagnetic actuator 120 or There is a concern that valve malfunction such as sliding lock may be induced. Further, the metal touch state of the engaging portion is exposed to deposits and moisture, and thus metal corrosion progresses with time, and there is a possibility that foreign matter intrudes into the stator core 132.

  In order to solve the above-described problems of sealing properties and corrosiveness, for example, the annular portion 151 is processed with rubber coating or rubber baking, or a sealing member such as an O-ring is added to improve sealing performance and resistance. Although it is possible to improve the corrosiveness, there is a concern that the cost increases due to an increase in the number of parts and the number of processing steps. Further, as a technical problem, in the case of locking via an elastic material such as rubber, the presser foot allowance is changed due to the variation of the spring load, and as a result, the attractive force characteristics of the electromagnetic actuator 120 may be affected. There is.

JP 2005-265482 A

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and it is possible to prevent foreign matter from entering the electromagnetic actuator without affecting the attractive force characteristics of the electromagnetic actuator. An object of the present invention is to provide an electromagnetic secondary air control valve that does not cause a failure.

[Means of Claim 1]
According to the first aspect of the present invention, the housing in which the air flow path is formed and the housing is accommodated in the housing, moved to one side to open the air flow path, and moved to the other side. A valve body that closes an air flow path, a valve shaft that is integrally coupled to the valve body, an electromagnetic valve driving device that drives the valve shaft in the valve opening direction, and a spring that biases the valve shaft in the valve closing direction And a dust seal that prevents foreign matter from passing around the valve shaft and entering the solenoid valve drive device, wherein the dust seal has a small-diameter seal portion and a diameter. The large-diameter seal portion is provided with a two-stage cylindrical seal portion, the small-diameter seal portion is in sliding contact with the outer peripheral surface of the valve shaft on the inner peripheral side, and the large-diameter seal portion is larger than the small-diameter seal portion. There is a contact surface on the outer peripheral side, the contact surface is pressed by the load of the spring, and the predetermined locking part It is characterized in that in contact.

  As a result, when a reverse flow occurs, a part of the reverse flow can be blocked by the small-diameter seal portion, and the remainder of the reverse flow can be blocked by the large-diameter seal portion, so that foreign matter enters the solenoid valve drive device. Can be reliably prevented.

[Means of claim 2]
According to the second aspect of the present invention, an annular protrusion is attached to the contact surface of the large-diameter seal portion, and the protrusion is in contact with a predetermined locking portion.
As a result, the annular protrusion easily starts elastic deformation, and a high surface pressure can be ensured by deformation of only the protrusion with respect to a predetermined spring load, thereby enabling reliable sealing. In addition, since the entire projecting portion is compressed and deformed uniformly with respect to a predetermined spring load, the contact surface of the large-diameter seal portion can be brought into close contact with the locking portion at this time. Therefore, the press in the metal touch state is locked without floating or rattling, and the suction force characteristic of the electromagnetic valve driving device is not affected.

[Means of claim 3]
According to a third aspect of the present invention, the contact surface of the predetermined locking portion has a contact surface that contacts the large-diameter seal portion, and an annular protrusion is formed on the contact surface. The protrusion is attached to the large-diameter seal portion.
Thereby, like the means of Claim 2, high surface pressure can be ensured and a reliable seal | sticker is attained. Further, there is no effect on the attractive force characteristics of the electromagnetic valve driving device.

[Means of claim 4]
According to the means of claim 4, the predetermined locking portion has a large-diameter locking portion and a small-diameter locking portion in which steps having different diameters are formed in the radial direction. The step between the large locking portion and the small locking portion is characterized by substantially matching the height of the large-diameter seal portion of the dust seal.
Thereby, it can prevent reliably that a foreign material penetrate | invades in an electromagnetic valve drive device, without affecting the attraction force characteristic of an electromagnetic valve drive device.

It is sectional drawing which showed the whole structure of the electromagnetic type secondary air control valve (Example 1). It is sectional drawing which showed the principal part of the electromagnetic type secondary air control valve, (a) shows the structure before the assembly | attachment which does not load a dust seal, (b) after the assembly | attachment which applied the load to the dust seal A structure is shown (Example 1). It is sectional drawing which showed the principal part of the electromagnetic type secondary air control valve (modified example of Example 1). (A) is sectional drawing which showed the whole structure of the electromagnetic type secondary air control valve, (b) is an expanded sectional view which showed the principal part of the electromagnetic type secondary air control valve (conventional example).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail together with examples shown in the drawings.

[Configuration of Example 1]
The electromagnetic secondary air control valve is used for activating the three-way catalyst by guiding the secondary air generated by operating the air pump to the three-way catalytic converter when starting the engine, particularly when the exhaust gas temperature is low. The secondary air is connected between the secondary air passage pipe of the secondary air supply device and the engine exhaust pipe, and the secondary air passage is opened and closed to introduce and block the secondary air.

  As shown in FIG. 1, the electromagnetic secondary air control valve 1 of the present embodiment has an air flow (hereinafter referred to as forward flow) only in the direction from an air pump (not shown) to a three-way catalytic converter (not shown). A check valve 2 that allows air flow in the opposite direction (hereinafter referred to as reverse flow) and secondary air that is pressure-fed and supplied from an air pump into an engine exhaust system (particularly a three-way catalytic converter). ) Includes a solenoid valve 3 that opens and closes a secondary air flow path, and a pressure sensor 4 that is integrally mounted on the solenoid valve 3.

  Here, the pressure sensor 4 converts the secondary air pressure in the secondary air flow path of the electromagnetic valve 3 into an electric signal, and the electric signal output from the pressure sensor 4 causes an abnormal failure of the air pump or the electromagnetic valve 3. It is input to a failure diagnosis circuit (not shown) to be diagnosed. An engine control device (hereinafter referred to as ECU, not shown) includes a pump drive circuit (not shown) for energizing and controlling the electric motor of the air pump based on the operating state of the engine, based on the operating state of the engine. A solenoid valve drive circuit (not shown) for energizing and controlling the solenoid assembly 5 of the solenoid valve 3 is provided. From the solenoid valve drive circuit, a solenoid valve drive current is output to the solenoid assembly 5 of the solenoid valve 3 via a pair of solenoid valve drive terminals 6. In addition, an electrical signal is input to the failure diagnosis circuit from the pressure sensor 4 via a pair of pressure detection terminals 7.

  The check valve 2 is a valve that prevents exhaust gas flowing from the exhaust manifold (not shown) of the engine to the three-way catalytic converter from flowing back to the air pump or the electromagnetic valve 3 in the engine exhaust pipe. The check valve 2 regulates the metal plate 9 that forms an air passage port 8 through which secondary air passes, the reed valve 10 that opens and closes the air passage port 8, and the degree of opening of the reed valve 10. And a valve case 12 that holds the metal plate 9. The metal plate 9 is made of, for example, a metal material such as aluminum, and has a substantially Japanese-shaped frame-like portion that forms two air passage openings 8 through which air passes. Note that a substantially sun-shaped rubber seal material is fixed to the passage wall surface of the air passage port 8 by baking or the like to constitute the valve seat portion 13.

  The reed valve 10 is manufactured by, for example, an elastic thin plate made of a resin material, or a leaf spring made of a metal material, and has a tongue-like valve portion (free end portion) that opens and closes two air passage ports 8 on one end side. ) And a supported portion (fixed end portion) supported by the air downstream end face of the support portion of the metal plate 9 at the other end portion. When the upstream air pressure is higher than the downstream side, the tongue-shaped valve portion opens according to the pressure difference to generate a forward flow, and when the pressure difference disappears or the downstream side has a pressure higher than the upstream side. When it becomes higher, the tongue-shaped valve portion is closed by its own spring restoring force or the pressure difference in the reverse direction to prevent backflow.

  The lead stopper 11 is made of a metal plate, has a double tongue-like stopper portion (free end portion) for restricting the opening degree of the reed valve 10 on one end side, and a supported portion of the reed valve 10. It has a supported part (fixed end part) supported by the air downstream end face. Here, two through holes pass through the support portion of the metal plate 9, the supported portion of the reed valve 10, and the supported portion of the lead stopper 11. In these through holes, fastening screws for fastening and fixing the support portion of the metal plate 9, the supported portion of the reed valve 10 and the supported portion of the reed stopper 11 to the illustrated lower end surface of the electromagnetic valve 3 are inserted. ing.

  The valve case 12 is manufactured by aluminum die casting and has a secondary air flow path 14 therein. The secondary air passage 14 is a portion that communicates with the engine exhaust pipe on the upstream side of the three-way catalytic converter and feeds the secondary air of the air pump to the three-way catalytic converter. The valve case 12 has a joined portion that is fastened and fixed using a plurality of screws 16 to an annular joining portion provided on the opening side of the valve housing 15 of the electromagnetic valve 3 in the lower part of the figure. Further, the lower end portion of the valve case 12 shown in the figure is a portion that forms an outlet end portion of the secondary air flow path 14 formed in the electromagnetic secondary air control valve 1 and is provided on the engine exhaust pipe. It is fastened and fixed to a stay portion (not shown) using a fixing bolt (not shown). A plurality of screw holes 17 into which fastening screws are screwed are formed in the illustrated lower end surface of the valve case 12.

  The electromagnetic valve 3 integrally couples the valve case 12 described above, and forms a valve housing 15 that forms an air passage port 18 through which secondary air passes, and secondary air formed in the valve housing 15. A poppet valve 19 that opens and closes the flow path, an electromagnetic actuator 20 that drives the poppet valve 19 in the valve opening direction, and a coil spring 21 that biases the poppet valve 19 in the valve closing direction are configured.

  The valve housing 15 is manufactured by aluminum die casting, and includes a cylindrical side wall portion that accommodates and holds the electromagnetic actuator 20 therein, and a circular pipe joint 22 that extends to the left from the lower end portion of the side wall portion in the drawing. It is integrally formed. The pipe joint 22 is a part that forms an inlet end of a secondary air flow path formed in the electromagnetic secondary air control valve 1, and is a discharge port of the air pump and a secondary air pipe (not shown). ) To connect through.

  Further, a frame-like wall (partition wall) 23 for partitioning the secondary air flow path into the upstream side and the downstream side is integrally formed on the lower end side of the side wall portion in the figure. A central portion of the frame-like wall 23 is an opening, and the opening constitutes an air passage port 18 that forms a valve hole of the electromagnetic valve 3. An annular valve seat 24 on which the poppet type valve 19 is seated is provided at the peripheral edge of the air passage 18 on the lower end side of the frame-like wall 23 in the figure.

  Here, the secondary air flow path formed in the valve housing 15 of the electromagnetic valve 3 of the present embodiment is a secondary air flow path formed upstream of the frame-like wall 23 in the flow direction of the secondary air. 25 and a secondary air flow path 26 formed in communication with the secondary air flow path 25 and downstream of the frame-like wall 23 in the flow direction of the secondary air. The secondary air passage 26 communicates with the secondary air passage 14 formed in the valve case 12 of the check valve 2 through the air passage port 8 of the check valve 2.

  The poppet type valve 19 has an annular plate-like valve portion around which a rubber-based elastic body is fixed by using means such as baking, and is configured to reciprocate in the axial direction integrally with the valve shaft 27. ing. The poppet-type valve 19 closes the air passage port 18 by being seated on a valve seat 24 provided on the frame-like wall 23 of the valve housing 15, and opens the air passage port 18 by being separated from the valve seat 24. The valve shaft 27 is formed in a two-step shape having different diameters, and a step between the large diameter portion on the valve portion side, the small diameter portion on the counter valve portion side, and the large diameter portion and the small diameter portion. Part. Further, an upper end hook-shaped portion having a smaller diameter is provided at the upper end of the small diameter portion on the side opposite to the valve portion. An annular dust seal 28 for preventing dust and the like entering along the sliding outer peripheral surface of the valve shaft 27 is attached to the outer periphery of the intermediate portion of the large diameter portion of the valve shaft 27.

  Furthermore, a pressure plate 30 that functions as a stopper for restricting the maximum lift amount of a plunger 29 and a poppet type valve 19 to be described later is installed on the upper end side of the dust seal 28 in the figure. The coil spring 21 is held on the outer peripheral side of the large diameter portion of the valve shaft 27 and the cylindrical portion (spring inner diameter guide) of the pressure plate 30, and one end thereof is locked to the flange-shaped portion of the pressure plate 30. The other end is locked to the plunger 29 to generate a biasing force that restores the plunger 29 to its original position. Therefore, the poppet type valve 19 is closed by this biasing force.

  The electromagnetic actuator 20 is valve body driving means that is press-fitted and assembled to the inner periphery of the side wall portion of the valve housing 15 of the electromagnetic valve 3 and drives the poppet type valve 19 in the valve opening direction. The electromagnetic actuator 20 is integrally formed with a yoke 31, a substantially cylindrical stator core 32 that forms a substantially cylindrical coil housing portion between the yoke 31, the poppet type valve 19, and the valve shaft 27. The movable plunger 29 and the solenoid assembly 5 that generates magnetic flux when energized are configured. A plurality of magnetic bodies such as the yoke 31, the stator core 32, and the plunger 29 form a magnetic circuit together with the solenoid coil 33.

  In the electromagnetic actuator 20 of the present embodiment, the secondary air flow path 25 formed in the valve housing 15 of the electromagnetic valve 3 includes a magnetic circuit including the solenoid coil 33, the yoke 31, the stator core 32, and the plunger 29. , 26 above the figure. Of these magnetic bodies, the yoke 31 and the stator core 32 are fixed iron cores each having a cylindrical portion. The yoke 31 and the coil bobbin 34 are accommodated between the outer diameter side of the stator core 32 and the inner diameter side of the yoke 31. It has a cylindrical coil housing. An annular ceiling wall is formed on the upper end of the cylindrical portion of the yoke 31 in the figure so as to close the opening of the cylindrical portion of the yoke 31. The top wall is provided with a terminal lead wire extraction hole 35 for extracting a pair of terminal lead wires of the solenoid coil 33.

  An annular outer flange portion 47 and an inner locking portion 48 that form a flow path wall of the secondary air flow path 25 are formed at the lower end portion of the stator core 32 in the figure. In addition, a concave portion is formed on the outer diameter of the cylindrical portion of the stator core 32, and a thin portion 36 that reduces the magnetic path cross-sectional area is provided. This thin portion 36 significantly increases the magnetic flux resistance, increases the magnetic saturation, and makes it easy for the magnetic flux to bypass to the plunger 29 side. As a result, when magnetic flux flows through the magnetic circuit of the yoke 31, the stator core 32, and the plunger 29, the plunger 29 is attracted to the attraction portion of the stator core 32 and moved downward in the figure.

  The plunger 29 is a movable iron core formed in a substantially cylindrical shape, and a small-diameter portion of the valve shaft 27 of the poppet type valve 19 is fitted in the center portion. The plunger 29 has a locking portion that locks a step portion provided between a large diameter portion and a small diameter portion of the valve shaft 27 of the poppet type valve 19. An annular washer 37 is inserted between the illustrated upper end surface of the plunger 29 and the upper end flange portion of the valve shaft 27.

  Note that the outer diameter of the upper flange portion of the valve shaft 27 is wider than the through hole of the plunger 29. This is because the plunger 29 is inserted into the cylindrical portion of the stator core 32 from above in the figure, and then the valve shaft 27 is inserted into the through hole of the plunger 29 from below in the figure. It is caulked by spin caulking. As a result, an upper end hook-like portion extending in the radial direction is formed, and the plunger 29 is sandwiched between the upper end hook-like portion of the valve shaft 27 and the stepped portion. Therefore, the plunger 29 and the poppet type valve 19 can operate integrally.

  The solenoid assembly 5 includes a solenoid coil 33 wound around the outer periphery of the coil bobbin 34, a pair of solenoid valve drive terminals 6 connected to the terminal lead wires of the solenoid coil 33, and the outer diameters of the solenoid coil 33 and the coil bobbin 34. The secondary resin mold member 38 covers the side and holds the pair of solenoid valve driving terminals 6 and the pair of pressure detection terminals 7 together. The solenoid coil 33 is a winding obtained by winding a coil bobbin 34 with a conductive wire coated with an insulating film a plurality of times. The solenoid coil 33 is excited by energization to form a magnetic flux in a magnetic circuit such as the yoke 31, the stator core 32, and the plunger 29. A magnetic attractive force is generated in an appropriate gap between the plunger 29 and the stator core 32.

  The solenoid coil 33 has a coil part wound around the outer periphery of the coil bobbin 34 and a pair of terminal lead wires taken out from the coil part. The outer diameter side of the coil portion of the solenoid coil 33 is molded on the secondary resin mold member 38 and ensures insulation between the solenoid coil 33 and the yoke 31 when housed in the yoke 31. .

  The coil bobbin 34 is made of an electrically insulating resin, and has a substantially cylindrical tubular portion around which the coil portion of the solenoid coil 33 is wound, and a substantially annular shape provided on both ends of the tubular portion. A secondary resin mold member 38 is in close contact with the upper end surface and the outer diameter end surface of the upper-side hook-shaped portion of the two hook-shaped portions.

  The pair of solenoid valve driving terminals 6 is a plate-like conductor made of a metal plate. The pair of solenoid valve driving terminals 6 are molded on a secondary resin mold member 38 and are electrically insulated and protected. The solenoid valve drive terminal 6 has one end inserted into and coupled to a female connector (not shown) provided on the distal end side of the vehicle-side wire harness, and the other end connected to a pair of solenoid coils 33. For example, the terminal lead wire is joined by welding means. Thereby, the solenoid valve drive current output from the solenoid valve drive circuit of the ECU flows through the solenoid coil 33.

  The pressure sensor 4 includes a pressure detector (sensor unit) that converts the secondary air pressure in the secondary air flow path 25 of the electromagnetic valve 3 into an electrical signal, a circuit board 39 on which the sensor unit is mounted, and the circuit board 39. And a pair of pressure detection terminals 7 which are electrically connected to each other. The pressure sensor 4 is mounted on the secondary resin mold member 38 of the solenoid assembly 5 of the solenoid valve 3. Here, a semiconductor pressure sensor using the piezoresistance effect of a semiconductor single crystal is used as the sensor unit, a silicon single crystal is processed into a diaphragm shape, formed into a thin film on the surface thereof, and electrically connected to the circuit board 39. It is connected.

  The pair of pressure detection terminals 7 is a plate-like conductor made of a metal plate. The pair of pressure detection terminals 7 are covered and held by the secondary resin mold member 38 of the solenoid assembly 5 of the solenoid valve 3. The pair of pressure detection terminals 7 have one end inserted into and coupled to a female connector (not shown) provided on the distal end side of the vehicle wire harness, and the other end connected to the circuit of the pressure sensor 4. It is coupled to the output terminal portion of the substrate 39 by using a joining means such as soldering.

  The outer flange portion 47 of the stator core 32 of the present embodiment is formed with a pressure intake port 40 for taking in the secondary air pressure in the electromagnetic valve 3, and on the outer diameter side of the cylindrical portion of the stator core 32. A pressure transmission passage 41 is provided in which at least one axially continuous chamfer is formed to introduce secondary air pressure.

  A pressure introducing portion 42 that communicates with the pressure transmission passage 41 is formed above the secondary resin mold member 38 that covers the pressure sensor 4 and insulates the solenoid assembly 5, so that the secondary air pressure is taken in. The pressure is introduced into the pressure sensor chamber 43 through a pressure introduction path including a port 40, a pressure transmission passage 41, and a pressure introduction portion 42. In the pressure sensor chamber 43, a substantially cylindrical or rectangular tube-shaped sensor case 44 extends upward in the drawing so as to surround the pressure sensor 4, and the opening side of the sensor case 44 is hermetically closed by the sensor cover 45. It is peeling off.

  At this time, in this embodiment, a maze structure-like convex portion protruding into the pressure transmission passage 41 is formed from the lower end surface of the hook-like portion on the lower end side of the drawing among the two hook-like portions of the coil bobbin 34. Yes. The convex portion of the labyrinth structure constitutes a labyrinth seal means. Even if dust enters the pressure transmission passage 41 from the pressure intake port 40 of the stator core 32, the passage of the dust is suppressed by the labyrinth seal means, and the penetration of the dust to the pressure introducing portion 42 is prevented.

  A dust trap part (concave part) 46 is formed in the middle of the pressure transmission passage 41 using a thin part 36 formed on the outer diameter side of the cylindrical part of the stator core 32. In the dust trap portion 46, if dust enters the pressure transmission passage 41 from the pressure inlet 40 of the stator core 32 (secondary air is originally cleaned by an air filter or the like, but very fine dust However, the dust can be captured and stored. Therefore, it is possible to prevent dust and the like from entering the pressure introducing portion 42 of the solenoid assembly 5 from the dust trap portion 46.

  Next, invasion prevention of dust and the like via the inside of the stator core 32 will be described. Preventing dust and the like from entering the inside of the stator core 32 is not limited to dust contained in the secondary air, but also exhaust gas that flows backward against a transient or temporary exhaust gas flow that overlaps with specific conditions. It is necessary to cope with the intrusion of foreign substances such as deposits and condensed water contained in the gas. In the present embodiment, the dust seal 28 described above includes a two-stage cylindrical seal portion as described below, the small-diameter cylindrical seal portion is sealed on the inner peripheral side, and the large-diameter cylindrical seal portion is It is characterized by sealing on the outer peripheral side.

  As shown in FIG. 2A, the dust seal 28 is formed by integrating a metal ring portion 51 and a rubber cylindrical seal portion 52 by baking. The metal annular portion 51 is formed by punching a thin steel plate having a predetermined thickness into a ring shape, and the ring-shaped inner peripheral side forms a conical surface inclined or bent in the axial center direction, Baking with the rubber cylindrical seal portion 52 is strengthened, and a flat mounting surface is formed.

  The rubber cylindrical seal portion 52 is formed in a two-stage cylindrical shape having a small-diameter seal portion (lip portion) 54 and a large-diameter seal portion (shoulder portion) 53. In order to generate an appropriate sealing pressure when fitted on the outer peripheral surface of the valve shaft 27, the inner diameter is smaller than the valve shaft diameter and has an appropriate seal length in the valve shaft axial direction.

  On the other hand, the shoulder portion 53 has a step that is one step lower than the lip portion 54, and the outer diameter thereof is larger than the outer diameter of the lip portion 54, and is half the difference between the outer diameter and the inner diameter of the metal annular portion 51. To the substantially central portion, i.e., the conical surface formed on the inner peripheral side of the annular portion 51 extends to the proximal end portion, and the distance from the proximal end portion to the step, that is, the shoulder portion 53 The height is also set to a predetermined dimension. The surface constituting the step forms a flat contact surface S perpendicular to the center line of the cylindrical dust seal 28, that is, the axial direction of the lip portion 54.

  The contact surface S is provided with an annular protrusion (bead) 55 having an outer diameter that is at least smaller than the outer diameter of the shoulder portion 53 and having a predetermined height. The cross-sectional shape of the bead 55 is not particularly limited, but when the bead 55 comes into contact with a contacted portion (predetermined locking portion), first, elastic deformation progresses uniformly over the entire circumference of the bead 55. Any shape can be used as long as it can easily reach a predetermined surface pressure. For example, it may be a semicircle, an inverted triangle, or a trapezoid. Further, it is preferable that the bead height in the pressing direction has a deformability such that a predetermined surface pressure or more is generated with respect to a predetermined spring load, and the entire amount of the bead height is crushed so that the contact surface S is in close contact with each other. Further, since the deformability of the bead 55 is affected by the hardness (softness) of the rubber material as well as its cross-sectional shape, the selection of the cross-sectional shape must be determined in consideration of the hardness of the rubber material.

  In addition, an inner locking portion 48 protruding inward is provided on the axial center side of the outer flange portion 47 of the stator core 32. The inner locking portion 48 includes a large diameter large locking portion 49 and a small diameter. The small locking portion 50 is coaxially formed with a predetermined step. The dimension value of the predetermined step is the same as the height of the shoulder portion 53 described above, that is, the distance from the contact surface S of the shoulder portion 53 to the opposing surface including the proximal end portion of the annular portion 51. The minimum inner diameter of the large-diameter engaging portion 49 is larger than the outer diameter of the shoulder portion 53 and smaller than the outer diameter of the annular portion 51. The minimum inner diameter of the small-diameter engaging portion 50 is smaller than the outer diameter of the shoulder portion 53 and larger than the outer diameter of the lip portion 54. Thereby, in the dust seal 28, the annular portion 51 is attached to the large-diameter engaging portion 49 of the inner engaging portion 48, and the shoulder portion 53 of the cylindrical seal portion 52 contacts the small-diameter engaging portion 50.

  Therefore, the assembly of the dust seal 28 to the valve shaft 27 of the poppet type valve 19 is performed as follows with reference to FIGS. First, the dust seal 28 is inserted into the cylindrical portion of the stator core 32 and engaged with the inner locking portion 48 on the axial center side of the outer flange portion 47 in the lower end direction in the figure. Then, the valve shaft 27 is inserted into the lip portion 54 of the dust seal 28 from below in the figure. At this time, since the small diameter portion of the valve shaft 27 is smaller (thin) than the inner diameter of the lip portion 54, the valve shaft 27 can be smoothly inserted. Then, reaching the large diameter portion of the valve shaft 27, the lip portion 54 expands outward to form an appropriate seal pressure and is brought into sliding contact.

  Then, the pressure plate 30 and the coil spring 21 are sequentially inserted from above the stator core 32 along the valve shaft 27 until they abut against the dust seal 28. Then, the plunger 29 is fitted with the small diameter portion of the valve shaft 27. The plunger 29 has a locking portion that locks a step portion provided between a large diameter portion and a small diameter portion of the valve shaft 27. An annular washer 37 is inserted between the illustrated upper end surface of the plunger 29 and the upper end hook-shaped portion of the valve shaft 27, and the upper end of the valve shaft 27 is caulked by, for example, spin caulking or the like. 29 and the valve shaft 27 are integrated.

  At this time, the coil spring 21 is compressed to a predetermined dimension value, and an urging force in the valve closing direction is applied to the plunger 29. At the same time, the metal annular portion 51 of the dust seal 28 is pressed by the spring load accompanying the urging force and pressed against the large-diameter locking portion 49 of the inner locking portion 48.

  As a result, the metal annular portion 51 is pressed and fixed to the large-diameter engaging portion 49, and the shoulder portion 53 of the rubber cylindrical seal portion 52 and the small-diameter engaging portion 50 come into contact with each other. At this time, the bead 55 attached to the contact surface S of the shoulder portion 53 is easily elastically deformed with respect to a predetermined load of the coil spring 21 to generate an appropriate seal surface pressure, and substantially the entire region is elastically deformed. Thus, the contact surface S can be brought into close contact uniformly (see FIG. 2B). By ensuring the close contact of the contact surface S, the electromagnetic actuator 20 can ensure a predetermined attractive force characteristic.

[Operation of Example 1]
The operation of the electromagnetic secondary air control valve 1 of this embodiment will be briefly described with reference to FIGS.

  When the exhaust gas temperature immediately after the engine is started is low, a pump drive current is applied to the electric motor of the air pump via the pump drive circuit by a control signal from the ECU. Further, according to the control signal of the ECU, the electromagnetic valve driving circuit, the vehicle-side wire harness, the female connector provided on the distal end side of the vehicle-side wire harness, the male connector, and the pair of electromagnetic valve driving terminals 6 are used. A solenoid valve drive current is applied to the solenoid coil 33 of the solenoid valve 3.

  As a result, the solenoid coil 33 is excited, magnetic flux flows through the yoke 31, the stator core 32, the plunger 29, and the like that form the magnetic circuit, and the plunger 29 is attracted to the suction portion of the stator core 32, so that the plunger 29 moves downward in the figure. To do. As the plunger 29 moves downward in the figure, the poppet type valve 19 fixed to the plunger 29 moves downward in the figure against the urging force of the coil spring 21. As a result, the poppet type valve 19 is separated from the valve seat 24, thereby opening the air passage port (valve hole) 18.

  Accordingly, the secondary air that has flowed into the electromagnetic valve 3 from the discharge port of the air pump through the secondary air flow path pipe is a secondary air flow path 25 and an air passage opening (valve hole) 18 formed in the valve housing 15. , And the secondary air flow path 26, flows into two air passage openings 8 formed in a substantially sun-shaped frame-like portion of the metal plate 9 of the check valve 2. Then, due to the pressure difference between the air pressure in the two air passage ports 8 and the air pressure in the secondary air flow path 14, the tongue-shaped valve portion of the reed valve 10 bends downward in the figure, and the valve portion is the reed stopper. The two air passage openings 8 are opened by abutting the 11 stopper portions.

  Thereby, the secondary air that has flowed into the two air passage ports 8 flows into the engine exhaust pipe upstream of the three-way catalytic converter via the secondary air flow path 14, and the secondary air enters the three-way catalytic converter. It is sent. For this reason, even when the exhaust gas temperature immediately after engine startup is low, the secondary air is guided to the three-way catalytic converter to promote the oxidation action of unburned hydrocarbons (HC), and the temperature of the three-way catalyst rises. Activated.

  At this time, when the engine starts, when the pressure rise is delayed due to the start-up delay of the air pump and the transient reverse flow due to the back pressure rise due to the exhaust pulsation occurs, the reverse flow may directly hit the dust seal 28. 54 and the shoulder portion 53, so that no foreign matter such as deposits and intrusion into the electromagnetic actuator 20 occur in the metal ring portion 51.

[Effect of Example 1]
In the electromagnetic secondary air control valve 1 provided with the dust seal 28 for preventing foreign matter from entering the electromagnetic actuator 20, the dust seal 28 of the present embodiment has a two-stage cylindrical seal portion 52 including a lip portion 54 and a shoulder portion 53. The lip portion 54 is in sliding contact with the outer peripheral surface of the valve shaft 27 on the inner peripheral side thereof, and the shoulder portion 53 has an abutment surface S on the outer peripheral side of the lip portion 54 having a small diameter. The surface S is pressed by the spring load and comes into contact with the small-diameter locking portion 50 of the inner locking portion 48. Further, a bead 55 is attached to the contact surface S of the shoulder portion 53, and when pressed by a predetermined spring load, the entire amount in the height direction of the bead 55 is crushed to ensure a predetermined surface pressure and contact. The surface S is in close contact with the small diameter locking portion 50.

  As a result, even if a transient delay in the pressure increase in the secondary air flow path 25 of the electromagnetic secondary air control valve 1 and the occurrence of exhaust pulsation overlap immediately after starting the engine, It is possible to prevent the reverse flow from directly colliding with the metal annular portion 51, or deposits, condensed water, etc. included in the reverse flow to enter a slight gap in the annular portion 51. Further, the bead 55 is attached to the contact surface S of the shoulder portion 53 to increase the elastic deformation capability against the spring load and easily reach a predetermined surface pressure, so that the bead 55 is completely crushed against the predetermined spring load. The contact surface S can be in close contact with the small-diameter engaging portion 50. Thereby, the high operation accuracy of valve opening and closing can be maintained without fluctuation of the attractive force characteristics generated in the electromagnetic actuator 20.

[Modification]
In the first embodiment, the metal annular portion 51 is pressed and fixed to the large-diameter engaging portion 49, and the shoulder portion 53 and the small-diameter engaging portion 50 of the rubber cylindrical seal portion 52 are provided. Are brought into contact with each other. At this time, the bead 55 was attached to the contact surface S of the shoulder portion 53. The bead 55 attached to the contact surface S of the shoulder portion 53 increases the elastic deformability with respect to the spring load and easily reaches a predetermined surface pressure. A predetermined surface pressure is generated with respect to the spring load, and the entire protrusion height of the bead 55 is uniformly crushed to bring the contact surface S into close contact.

  The present modification is not limited to this, and the bead 55 is attached to the small-diameter engaging portion 50 side. As shown in FIG. 3, an annular bead 55 having a triangular cross-section and continuous in the circumferential direction is attached to the inner side of the small-diameter locking portion 50 facing the contact surface S of the shoulder portion 53. The center diameter of the annular bead 55 is at least larger than the inner diameter of the small-diameter engaging portion 50 and smaller than the outer diameter of the shoulder portion 53, and is preferably located at the central portion in the radial direction of the contact surface S of the shoulder portion 53. Further, the protruding height of the bead 55 is preferably a minimum dimension that generates a predetermined surface pressure below the upper limit of the elastic deformability of the rubber material of the contact surface S of the shoulder portion 53.

  That is, it is preferable that the deformation of the contact surface S of the shoulder portion 53 is local elastic deformation only in the vicinity of the bead 55, and this local deformation is not a deformation amount enough to change the outer diameter shape of the shoulder portion 53. . Accordingly, it is possible to make close contact with the contact surface S that locally secures a predetermined surface pressure while maintaining the outer diameter shape.

Thereby, when the dust seal 28 is fixed to the inner locking portion 48 by pressing a predetermined spring load, the metal annular portion 51 is pressed and fixed to the large-diameter locking portion 49, and the rubber seal portion 48 is made of rubber. The shoulder portion 53 of the cylindrical seal portion 52 and the small-diameter engaging portion 50 are brought into contact with each other, and the contact surface S can be brought into close contact while maintaining a predetermined local surface pressure by the bead 55. Therefore, both the inner and outer peripheral sides of the dust seal 28 are sealed, and foreign matter can be prevented from entering the electromagnetic actuator 20 without affecting the attractive force characteristics of the electromagnetic actuator 20 as in the first embodiment. .

1 Electromagnetic secondary air control valve 15 Valve housing (housing)
19 Poppet type valve (valve)
20 Electromagnetic actuator (Electromagnetic valve drive device)
21 Coil spring (spring)
25, 26 Secondary air flow path (air flow path)
27 Valve shaft (valve shaft)
28 Dust seal 48 Inner locking portion 49 Large diameter locking portion 50 Small diameter locking portion (predetermined locking portion)
52 Cylindrical seal part 53 Shoulder part (large diameter seal part)
54 Lip (small diameter seal)
55 Bead
S Contact surface

Claims (4)

A housing having an air flow path formed therein;
A valve body that is housed in the housing, opens the flow path of the air by moving to one side, and closes the flow path of the air by moving to the other side;
A valve shaft coupled integrally with the valve body;
An electromagnetic valve driving device for driving the valve shaft in the valve opening direction;
A spring for urging the valve shaft in the valve closing direction;
A dust seal that prevents foreign matter from passing around the valve shaft and entering the electromagnetic valve drive device, and an electromagnetic secondary air control valve comprising:
The dust seal includes a two-stage cylindrical seal portion including a small-diameter seal portion and a large-diameter seal portion,
The small-diameter seal portion is in sliding contact with the outer peripheral surface of the valve shaft on the inner peripheral side,
The large-diameter seal portion has an abutting surface on the outer peripheral side of the small-diameter seal portion, and the corresponding contact surface is pressed by the load of the spring and is in contact with a predetermined locking portion. An electromagnetic secondary air control valve. The electromagnetic secondary air control valve according to claim 1,
An annular protrusion is attached to the contact surface of the large-diameter seal portion,
The electromagnetic secondary air control valve, wherein the protrusion is in contact with the predetermined locking portion. The electromagnetic secondary air control valve according to claim 1,
The predetermined locking portion has a contact surface that contacts the large-diameter seal portion,
An electromagnetic secondary air control valve, wherein an annular protrusion is attached to the contact surface, and the protrusion is in contact with the large-diameter seal portion. In the electromagnetic secondary air control valve according to any one of claims 1 to 3,
The predetermined locking portion has a large-diameter locking portion and a small-diameter locking portion in which steps having different diameters are formed in the radial direction,
The electromagnetic secondary air control valve according to claim 1, wherein a step between the large-diameter engaging portion and the small-diameter engaging portion substantially coincides with a height of the large-diameter seal portion of the dust seal.

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