Patent Application
20060027218
The present invention relates to a positive crankcase ventilation valve for an internal combustion engine, and in particular to a heated positive crankcase ventilation valve.
A positive crankcase ventilation (PCV) system prevents unburned vapors from escaping an engine into the atmosphere. Known PCV systems include a valve (commonly referred to as a PCV valve) that typically has a spring, a plunger, and a hollow outer housing with an inlet and an outlet. The entire PCV valve intersects a tube that connects a crankcase to an intake manifold of the engine. The PCV valve reacts to changes in manifold vacuum pressure as it opens and closes the passageway that leads to the intake manifold. As the pressure increases in the manifold, the high vacuum overcomes the tension of the spring and causes the valve plunger to plug the opening within the valve, thereby reducing the flow of vapors. Under normal operating conditions the PCV valve is effective in reducing the amount of vapors escaping the engine. However, known PCV valves have been found to be less effective in cold environments, e.g. environments where the temperature is −55° C. or below. In cold environments, the presence of water within the system may cause the PCV valve to freeze. Accordingly, the PCV valve may be ineffective in preventing unburned vapors from escaping the engine.
In an effort to reduce the possibility of freezing of the PCV valve, one known approach is to heat the PCV valve by integrating a heating element into the valve housing. A method of carrying out this approach is the inclusion of a heating element having a heat sink with a resistance heating member disposed within the PCV valve. The heat sink is a thermally conductive metal cup that is directly exposed to the flow of crankcase gases. Alternatively, the heating element may consist of a single heat source, e.g., a PTC heater, without a heat sink attached thereto.
While, the above approach has been found effective, the addition of the heating element considerably increases cost and packaging considerations. For instance, the PCV valve housing must be designed to accommodate an additional heating element. Manufacturing costs increase as a result of having to manufacture the heating element. Furthermore, it is possible that the thermally conductive metal cup could become clogged or rusted, further reducing the effectiveness of the PCV system. Moreover, the addition of a component such as the heating element increases the amount of failure modes present in the PCV system. It would be desirable therefore to provide a PCV valve which reduces the complexity and cost of the known PCV valve systems while having the capability of operating in a cold environment.
The inventor of the present invention has recognized these and other problems associated with PCV systems in cold environments. To this end, the inventor has developed a PCV valve having a housing constructed of an electrically conductive material. The electrically conductive material may be comprised of a mineral and glass filled thermoset. The resins may be comprised of a vinyl ester, polyester, or phenolic base. In accordance with one aspect of the invention, the housing of the PCV valve has at least one electrode integrally molded therein. A spring and valve assembly is also included. The spring and valve assembly may be comprised of a metallic or plastic material. The plastic material may be acetel.
A method of making the inventive PCV valve is also disclosed, the method includes the step of forming a positive crankcase ventilation valve housing of an electrically conductive material. An additional step includes forming a valve and spring assembly. Yet another step includes installing the valve and spring assembly within the positive crankcase ventilation valve housing.
The accompanying drawings illustrate various embodiments of the present apparatus and method and are a part of the specification. The illustrated embodiments are merely examples of the present apparatus and method and do not limit the scope of the disclosure.
Referring now to
The PCV valve 10 includes an enclosed housing 12 that defines a hollow chamber 13 therein. The housing 12 further includes sidewalls 23, extending walls 27 that define a chamber 29, an inlet 14, an outlet 16, at least one electrode 18 integrated therein, and a valve and spring assembly 22. The housing 12 may optionally be integrated into a cam cover (not shown) of the engine.
The inlet 14 is operatively connected to the hollow chamber 13 and forms an aperture through which “blow-by” gases enter the hollow chamber 13 of the PCV valve 10 from the engine crankcase (not shown). In one embodiment, inlet 14 is positioned in a downwardly opening cup portion 19 that is defined by a downwardly extending wall 21 (as seen in
The housing 12 may be constructed of an electrically conductive material. In one embodiment, the electrically conductive material is a mineral and glass filled thermoset. More specifically, the mineral and glass filled thermoset may be comprised of a vinyl ester base, a polyester base, or a phenolic base. The housing 12 is preferably constructed as a unitary member.
Referring to
In accordance with one aspect of the invention, the electrode 18 enables heating of the PCV valve 10 by an application of electric current via the electrode contact 20. The source of the electric current may be a vehicle battery (not shown) or any other suitable power supply well known in the art. The power supply typically includes a female connection that receives the distal end 25 of the electrode contact 20. The electrode 18 and the electrode contact 20 are also comprised of an electrically conductive material that generates heat when energized by electric current. Heating the PCV valve 10 ensures proper and efficient functioning of the PCV valve 10 in colder temperatures (e.g., −55° C.) as will be discussed in more detail below. The electrode 18 as illustrated has a substantially rectangular shape. However, the electrode 18 may be any shape or configuration that is suitable for the particular vehicle application.
Referring to
In one embodiment, spring 26 includes a pair of spring arms 31a, 31b. Each spring arm 31a, 31b includes a first end 33 and a second end 35. First end 33 is connected to spring support 30. Second end 35 is connected to a bottom portion 37 of valve plunger 24. Spring arms 31a, 31b are preferably spiraled around valve plunger 24.
The washer 28 includes a central opening 41 that encircles a plunger arm 43 that extends from the bottom portion 37 of valve plunger 24. To insure that washer 28 is centered around plunger arm 43, a plurality of locating fingers 45 extend inwardly from the periphery of central opening 41.
As shown, the valve and spring assembly 22 may be a one-piece unit. As such, the valve plunger 24 is integrated with the spring 26. Furthermore, the spring 26 is also integrated with the spring support 30. The washer 28 cooperates with a sealing element 39 to enable sealing of the outlet 16 and locating the valve and spring assembly 22 within the housing 12 (as seen in
The valve and spring assembly 22 reacts to changes in manifold pressure. As the manifold pressure increases and surpasses a predetermined pressure threshold, the pressure forces the spring 26 to compress, causing the valve plunger 24 to “un-plug” the inlet 14 of the housing 12. As such, the un-plugged inlet 14 allows the passage of gases through the PCV valve 10.
In one embodiment, the valve and spring assembly may be comprised of a metallic material such as iron, steel, aluminum, or any other suitable metallic material. As discussed above, in colder temperatures the conventional PCV valve has a tendency to freeze, rendering the valve and spring assembly 22 non-responsive to changes in manifold pressure. According to an embodiment of present invention, application of an electric current to the integrated electrode 18 results in heating of the housing 12. Accordingly, by way of heat conduction from the housing 12, the temperature of the valve and spring assembly 22 increases. The increased temperature of the valve and spring assembly 22 prevents freezing of the valve and spring assembly 22 in colder temperatures. In another embodiment, the valve and spring assembly 22 may be comprised of a plastic material. As such, the valve and spring assembly 22 may be molded out of a plastic material such as acetel or any other suitable non-metallic material. Forming the valve and spring assembly 22 out of a non-metallic material such as acetel further reduces the probability of freezing. Because of the intrinsic characteristics of acetel, frozen vapor is less likely to form on the valve and spring assembly 22.
Referring now to
It should be understood that the aforementioned and other various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.
