US 3345976 A
Description (OCR text may contain errors)
oci; '10, 1967 J. A. POPE ET AL POPPET VALVES FOR INTERNAL COMBUSTION ENGINES 5, 1965 Filed June 1 2 Sheets-Sheet 1 A H B v v A mvsmom T aww QLauL-r RP; ETOFM Zita- K1 3,345,976 POPPET VALVES FOR INTERNAL COMBUSTION ENGINES Filed June 15, 1965 Oct. 10, 1967 J. A. POPE ET AL 2 Sheets-Sheet 2 00 1d 1Tc B's $4 ELBEJtr 516% m United States l atent O ABSTRACT OF THE DISCLOSURE A poppet valve for an internal combustion engine with lubrication and a cooled zone for the valve guide and stem, longitudinal lubrication passages being formed between the complementary sliding surfaces of the valve stem and guide to form part of the lubricant circulating system and so as tov provide flow in a longitudinal direction thereof.
This invention relates to poppet valves for internal combustion engines, and is particularly, though not exclusively, applicable to caged valve assemblies.
A major problem with such valves is the corrosion of the valve stem and/ or guide therefor, and in the case of exhaust valves this is mainly due to corrosive contents of the exhaust gases passing up the guide While the valve is open. This problem has been found to be intensified with the use of cooling for the valve and/ or guide, which cooling since its introduction is now extensively employed since it considerably extends the useful life of the head of the valve and of its seating.
The main object of the present invention is to increase the effective life of the valve and/or its guide, especially but not exclusively exhaust valves often prematurely determined by such corrosion.
One attempt to solve this problem has been by electroplating or cladding of the valve stem, or fabricating the valve so as to be able to make the stem of a metal different from the head and more suitable to resist such corrosion than is the normal valve metal. Both these methods have their known disadvantages. Corrosion of the guide is of course more easily reduced by the selection of appropriate materials in lieu of the usual cast iron, but this possibility of selection also has its problems and limitations.
Lubrication of the valve stem and valve guide again, while offering possibilities to reduce corrosion, brings its own problems, not the least of which would be to keep down resultant consumption of lubricating oil without prejudice to the certainty and reliability of the oil supply to the valve stem, since such supply would have to be at a pressure high enough relative to the pressure of the exhaust gases attempting to enter the valve guide while the valve is open, to preclude such entry.
The present invention is based on the appreciation of the aforesaid known prior art and relevant factors.
According to the invention, a poppet valve and guide of the kind in which pressure lubrication is provided between the valve stem and its guide, is characterized by means synchronized with the axial movement at least of the valve for providing an intermittent flow of pressurized lubricant in the working clearance between the valve stem and its guide while the valve is open and greater in volume than could occur in a normal working clearance between such parts.
The valve and guide aforesaid may be further characterized in that the valve stem is formed with longitudinal clearance passages relative to the bore of the guide and complementary to inlet and outlet port-s in the guide to open a flow passage when the valve is moved axially to an open position; or further characterized by lubricantsealing zones to reduce loss of lubricant; or further characterized by means for positively'rotating the valve and by lubricant passage formations so arranged as to provide a cycle of on and off periods for the intermittent form of pressurized lubricant with change of position of the valve in its cycle of rotation.
In the accompanying drawings:
FIG. 1 is a longitudinal section of one example of a poppet valve and guide assembly made in accordance with the present invention.
FIG. 2 is a longitudinal section of a modification of the assembly shown in FIG. 1.
As shown in FIG. 1 a poppet valve and guide assembly comprises a valve cage 10 and lower end 10a of which is formed with a valve seating 10b. The upper end of the cage is recessed at 10a to form a housing for valve springs described later. The cage is fitted in known manner with a renewable valve guide 11 and at its centre is shaped relative to the guide to provide a cavity 12 for the circulation of a coolant fluid medium, the entry and exit passages for which are not shown as they may be of any known construction and arrangement. The general shape and construction of the ports above described and illustrated are well known, including the valve with its stem 13, head 13a, springs 14 and 15 and collet assembly 16.
Sealing rings 11a are provided as shown.
The novel constructional features include passages 17, 18 and 19 in the upper end of the cage, flats 20 and 21 formed on opposite sides of the valve stem 13 complementary to the cross passage 18 located between the sealing rings 11a, while an annular groove 11b is formed in the bore of the valve guide just beyond the lower ends of the flats 20 and 21 when the valve is closed, as in the position shown. The axial length of the flats 20, 21 is such that in the normal position their ends are short of the end of the guide and annular groove respectively. The cross passage 18 is also so positioned that it is near, but at all times within the length of the flats 20 and 21.
In operation, lubricant under suitable pressure such as 10 p.s.i.g. (pounds per square inch gauge) is supplied to the passage 17 or 19 and when the valve is closed as shown it reaches only the adjacent valve stem flats 21 or 20. A continuous but small seepage of lubricant will occur from one flat to the other, along their whole length through the normal working clearance between the valve guide and its stem, to maintain a degree of lubrication. When however the valve is opened, the annular recess 11b connects the flats 21 and 20, so that the lubricant flows down one of the flats 20, 21, into and through said recess and back up the other flat. Such flow of lubrication is thereby intermittent as well as being greater in volume than could occur in the normal working clearance along and between the valve stem and its guide. Such greater volume of fiow ensures frequent change of the lubricant volume located in the annular recess 11b and renewal of lubricant in the flats 20, 21 and the normal working clearance between the valve stem 13 and its guide 11.
Under normal circumstances a valve, of a caged valve assembly, does not turn or rotate unless such rotation is deliberately induced, as in the second example. Once set during assembly for the flats 20, 21 and the cross passages 18 to be in register, they remain in register. However, to avoid any risk of loss of register, the number of the flats 20, 21 can be increased, as also the number of the passages 18, and the inner ends of such passages can be extended circumferentially in the guide so that in all positions one flat is always in connection with a port 16 shown in FIG. 1. A seal is provided at the upper end of the valve guide consisting of a thimble 23, enclosing a gland packing 24, and loaded by the inner valve spring towards a collar 110 on the valve guide. Further sealing rings 11d are provided between the thimble and the valve guide.
In operation, the assembly shown in FIG. 2 operates in exactly the same manner as the assembly of FIG. 1 when the flats 20 and 21 register and open as shown with the inner ends of the passage 18, but the rotation of the valve causes cycle change of register with resultant closing and opening of the ends of such passage so that the intermittence of the flow is determined not only by the opening of the flats 20, 21 to the annular recess 11b but also by the rotation of the valve causing cycle change of register with closing of the ends of the passage 18.
The invention is not limited to the details of the two examples above described. For instance, the valve seating 10b could be provided as an insert, in known manner, instead of being formed in the end of the valve cage itself.
1. In a poppet valve and guide assembly of the kind in which pressure lubrication is provided for the working clearance between the valve stem and guide having means for rotating the valve, in combination at least two longitudinal lubricant passages formed on the valve stem within the length of said guide, port means in the guide for leading lubricant to one end of one such passage and away from an adjacent end of another, and an annular passage formed in the guide so positioned as to connect the other ends of said passages when the valve is in its open position, the ports and longitudinal passages being so arranged that they are progressively brought into and out of register with each other by reason of rotation of the valve.
2. A poppet valve assembly comprising a cage, a valve guide mounted in said cage, a valve stem movable axially in said guide, at least two separate longitudinal flats in said valve stem, an inlet for pressurized lubricant in said guide communicating with one of said flats, an outlet for lubricant in said guide located for simultaneous communication with another of said flats, an annular groove in said guide spaced from the ends of said flats when said valve is closed but communicating therewith when said valve is open, said inlet and outlet being within the length of said flats in all positions of said valve.
3. A poppet valve assembly according to claim 2 characterized in that means are provided for positively rotating said valve to cause cyclic change of register of flats with said inlet and outlet.
4. A poppet valve assembly according to claim 2 characterized in that sealing rings and provided at the junction of said guide and cage above and below said inlet and outlet.
References Cited UNITED STATES PATENTS 1,482,478 2/1924 Milligan l23-90 1,569,455 1/1926 Burwell 123188 1,938,042 12/1933 Robinson 1846 2,069,745 2/1937 Allen 1846 2,354,926 8/1944 Patterson 1846 2,716,972 9/1955 Farny et al. 123188 X AL LAWRENCE SMITH, Primary Examiner.