Solenoid Valve For Recycling Exhaust Gases In Internal Combustion Engines

Abstract

In an internal combustion engine including a return conduit connecting the exhaust pipe with the intake manifold to recycle one part of the exhaust gases, there is provided in said return conduit a solenoid valve which has a housing, a movable valve head for opening and closing said return conduit, an electromagnet held externally spaced from said housing by a spacer tube affixed to said housing and a valve rod passing through said spacer tube and carrying at one end said valve head and being secured, at its other end, to the movable armature of said electromagnet.

Description

BACKGROUND OF THE INVENTION

This invention relates to a solenoid valve for recycling exhaust gases in internal combustion engines in which, for the purpose of reducing harmful pollutants in the exhaust gas under certain operational conditions, one portion of the exhaust gas is returned from the exhaust pipe into the air intake tube by means of a valve member or valve head actuated through a valve stem by an electromagnet functioning as a setting member. The valve member, in one of its extreme positions (closing position), closes a passage and thus blocks the flow of exhaust gases through the valve housing and, in its other extreme position (open position), opens said passage and simultaneously closes another opening to prevent the exhaust gases from flowing to the setting member.

In a known solenoid valve of the aforeoutlined structure (as described, for example, in U.S. Pat. No. 1,439,231) which finds application as a gas valve in gas-heated stoves, there are provided means which, upon actuation of the electromagnet, cause a valve member to snap from the closed position into its open position. In the open position the valve member lies against an intermediate flange and seals a guide bore for the valve stem. Such a guide bore, however, in case the valve is intended to be used as an exhaust gas recycling valve, despite a rapid switching by snap action, would become soiled which would lead to a breakdown of the valve. Furthermore, the structure of the setting member in such a valve is quite complex and it could be easily damaged by the hot exhaust gases of the internal combustion engine.

In another known solenoid valve (as described in German Published Application DOS No. 2,002,163, FIG. 2) in which for decreasing the harmful pollutants in exhaust gases under certain operational conditions, one part of the exhaust gases is returned from the exhaust conduit into the air intake conduit, there is provided a setting member formed as an electromagnet, the armature of which has at one end a valve member which in one of its extreme positions (closing position) closes a passage and thus blocks the flow of the exhaust gases through the valve housing and in its other extreme position (open position) frees the aforenoted passage. This device, however, has the disadvantage that the armature is in direct contact with the exhaust gases. As a result, the armature may become soiled and thus jamming may occur. Furthermore, the solenoid winding is particularly endangered by the hot exhaust gases.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved solenoid valve for the partial recycling of exhaust gases in internal combustion engines, wherein the aforenoted disadvantages are eliminated and which operates in a very satisfactory manner even if dirt particles contained in the exhaust gas are passing through the valve member during the switching of the valve.

Briefly stated, according to the invention the setting member is provided with a guide bore for the valve stem and is connected with the valve housing by means of a thin-walled, sleeve-shaped spacer tube made of a material of low heat conductivity.

The invention will be better understood, as well as further objects and advantages will become apparent, from the ensuing detailed specification of a preferred, although exemplary, embodiment taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic side elevational view of an internal combustion engine, its exhaust conduit and the incorporated preferred embodiment of the invention and

FIG. 2 is a longitudinal sectional view of the preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to FIG. 1, to the exhaust gas conduit 10 of an internal combustion engine 11, preferably an Otto-engine, there is connected an exhaust gas recycling conduit 12 which, by means of a solenoid valve 13, is separated into two conduit portions 12a and 12b. The conduit portion 12b merges in the intake manifold 14 of the engine 11. The solenoid valve 13, which permits the recycling of one part of the exhaust gases from the exhaust conduit 10 into the intake manifold 14 under certain operational conditions, such as the partial load range, is connected by means of electrical conductors 15 with an electric control apparatus 16 of known structure. The control signals of the apparatus 16 may be generated in response to different operational magnitudes, such as the engine rpm, the vacuum in the intake manifold and/or the angular position of the butterfly valve (not shown). For the sake of clear illustration, the solenoid valve 13 is shown spaced from the engine and out of proportion with respect thereto. In practice, the solenoid valve 13 may be directly secured to the engine 11. In order to remove coarse impurities from the exhaust gases and to keep them away from the solenoid valve 13, there may be provided a filter 17 in the conduit portion 12a, as shown in phantom lines.

Turning now to FIG. 2, the solenoid valve 13 comprises a sheet metal valve housing 20 provided with an inlet nipple 21 and an outlet nipple 22 oriented at right angles with respect to the inlet nipple. Both nipples 21 and 22 communicate with a valve chamber 23 enclosed by the housing 20. About the mouth of the inlet nipple 21 in the valve chamber 23 there is provided a valve seat 24 with which there cooperates a valve head 25. The latter is connected by means of a valve rod 26 with the armature 27 of an electromagnet 28 which operates as a valve setting member and which is externally secured to the valve housing 20 by means of a thin-walled, sleeve-shaped spacer tube 31. The spacer tube 31, having an internal diameter D, is made of a material which has a very low heat conductivity for the purpose of preventing heat transmission from the hot exhaust gases in the valve housing 20 to the electromagnet 28. Preferably, the spacer tube 31 is made of a high-alloyed chromium nickel steel (V2A steel) which, in addition to a low heat conductivity, also has the advantage of having a superior corrosion resistance. To the outside of the spacer tube 31 there are attached cooling fins 32 made of thin metal sheet having a good heat conductivity.

The distance between the internal diameter D of the spacer tube 31 and the diameter d of the valve rod 26 is relatively large to accommodate -- without obstructing the motion of the valve rod 26 -- dirt particles carried by the exhaust gases and passing through the valve head 25 during a switching of the valve head position. Preferably, the diameter D is a multiple of the diameter d.

The valve rod 26 is guided in a guide bore 33 of the electromagnet 28. In an enlargement 34 of the guide bore 33 there is disposed a return spring 35 which engages the armature 27 and a base 36 of the enlargement 34. The coil 37 of the electromagnet 28 is connected through terminals 38, 38a to the conductors 15 leading to the control apparatus 16 (shown only in FIG. 1).

The valve head 25 is shown in one of its end positions (closing position) in which it is seated in valve seat 24 and thus blocks the passage of exhaust gases from the inlet nipple 21 through the valve housing 20. This position is assumed by the valve head 25 when the electromagnet 28 is in an energized condition. The air gap a necessary in the energized condition of the electromagnet may be set by turning the valve rod 26 which is secured to the valve head 25 by means of a thread 39. On the valve rod 26 beneath the valve head 25 there is threaded a counternut 41. The valve head 25 has a conical sealing face 42 cooperating with the valve seat 24. In its other end position (open position) the valve head 25 lies with its planar upper annular face 43 flat against a seat 44 which is situated in the valve chamber 23 opposite the valve seat 24 and which surrounds the mouth of the spacer tube 31. In this manner the spacer tube 31 is sealed so that no exhaust gases may enter thereinto during gas flow from the inlet nipple 21 to the outlet nipple 22 through the valve chamber 23. The terminus of the spacer tube 31 situated in the chamber 23 is bent outwardly to form a flange 45 which connects the valve housing 20 with the spacer tube 31 and the outer face of which constitutes the valve seat 44. The inlet nipple 21 is connected by means of a flange 46 with the return conduit portion 12a, while the outlet nipple 22 is connected by means of a flange 47 with the return conduit portion 12b.

The entire valve assembly 13 is tightened to the internal combustion engine housing 11 by means of an angle member 48 in a manner not shown in detail.

Claims

What is claimed is:

1. A solenoid valve for controlling the recycling of exhaust gases from the exhaust pipe into the intake manifold of an internal combustion engine comprising, in combination:

a. a valve housing having inlet and outlet means to permit passage of said exhaust gases through said housing in an open valve position;

b. an electromagnet functioning as a valve setting member;

c. a movable valve rod of given outer diameter extending to said electromagnet;

d. a first valve seat defining an opening establishing communication between said inlet and outlet means through said housing;

e. a second valve seat defining an opening through which said valve rod extends to said electromagnet;

f. a movable valve head situated in said housing and secured to said valve rod, said valve head being movable into a first position in which it is seated in said first valve seat for blocking the passage of exhaust gases through said housing, said valve head being movable into a second position in which it is spaced from said first valve seat for permitting the passage of exhaust gases through said housing, said valve head being seated in said second valve seat in said second position to prevent exhaust gases from passing to said electromagnet; and

g. a thin-walled, sleeve-shaped spacer tube having an inner diameter which is a multiple of at least two of said given diameter for accommodating, without obstructing motion of said valve rod, dirt particles carried by exhaust gases, said thin-walled sleeve being made of a material of low heat conductivity for preventing heat transmission from hot exhaust gases and said housing to said electromagnet, said spacer tube having one end affixed to said housing and another end affixed to said electromagnet, said spacer tube holding said electromagnet spaced from and externally of said housing, said valve rod passing longitudinally through said spacer tube and said thin-walled sleeve member being relatively thin with respect to its said inner diameter.

2. A solenoid valve as defined in claim 1, including cooling fins affixed externally to said spacer tube.

3. A solenoid valve as defined in claim 1, wherein said spacer tube extends into said housing and forms said second valve seat.

4. A solenoid valve as defined in claim 1, wherein said spacer tube is made from a high-alloyed chromium nickel steel.

5. A solenoid valve as defined in claim 2, wherein said cooling fins are made from a metal having a relatively greater heat conductivity than the material of said spacer tube.

6. A solenoid valve as defined in claim 5, including cooling fins affixed externally to said spacer tube, said cooling fins being made from a metal having relatively greater heat conductivity than said high-alloyed chromium nickel steel.