DE2905706A1 - Valve control of engines - in which rocker arm and camshaft are made of a chill casting - Google Patents

Abstract

In a valve control system of internal combustion engines the camshaft and rocker arms are made of a white chill casting which can be annealed and subsequently hardened, and having the structure (a) austenite including martensite, troostite, bainite, but not ferrite; and (b) carbide such as Fe-, Cr-, (Cr-Fe)-, and/or carbides alone or together of Nb, V, Mo. Pref. the white chill casting contains 2-4.5 wt.% C, 2-6 wt.% Ni, 0.5-10 wt.% Cr and 10% of Nb, V, Mo, B, Si. Prod. has longer life and can be machined without difficulty. Prodn. is simple. Used for rocker arms and camshaft in valves of internal combustion engines.

Description

"VALVE CONTROL"

(Description) The invention relates to the economic Generation of durable valve controls, consisting of camshafts and rocker arms, how they are used in engines for various purposes.

The camshaft must combine high wear resistance great dimensional rigidity, a high damping capacity compared to the occurring Vibrations, as well as good machinability, if possible also by turning and Bohrcn for the purpose of introducing oil channels, etc. @ The same applies to the rocker arm, the is subject to considerable abrasion at its contact surfaces with the camshaft.

Numerous attempts have been made by special measures to achieve a long-lasting combination. Nockencllen and rocker arms are so far mainly made of cast iron with lamellar or spheroidal graphite, malleable cast iron or cast steel generated. It was z. B. also tried the corresponding contact surfaces of the. camshaft more wear-resistant at these points than the rocker arm due to the so-called form alloying to make, in which in the form of alloying materials such. B.

Chromium, tellurium and other carbide-forming materials are suitable Way to be introduced.

Other measures to increase the wear resistance of such camshafts are the superficial hardening by flame hardening, Induction hardening or electron beam hardening. These measures have the goal of working together To harden contact surfaces on the surface without causing it to become inside the camshaft a structural transformation occurs. The aim was to achieve high wear resistance in the surface with good dampening capacity in the core.

Even with the rocker arm, you have various options for the superficial ones Coating, e.g. 13. also used by hard metal plates without b sher to a completely satisfactory valve control, which at low cost a has a long lifespan. Rocker arms are still in use today which are successively hard chrome plated, bath nitrided and induction hardened; on the The pressure surfaces of other rocker arms are turned into curved hard metal plates by induction solution attached. Shell hardness for rocker arms has also been suggested.

The previous solutions are time-consuming and cumbersome to use and expensive. The quality of the surface depends on numerous process steps and not always the same. Cracks in the surface can be caused by the influence of heat develop. The surface hardness layer that is achieved tends to flake and danit to endanger the engine and vehicle.

Extensive and again expensive tests have to be carried out.

In contrast, the present invention relates to a valve control for internal combustion engines, consisting of a camshaft and moved by this Rocker arms, which the latter actuate the valve shafts directly or indirectly, thereby characterized in that the camshaft and rocker arm consist of continuously solidifying white, suitably annealable and hardenable solid chilled cast alloys exist.

This means that previously unknown solutions are being proposed, some of them stand in contrast to the technical opinions that are widespread today and therefore as overcoming technical judgments can be assessed. Up to now, solid chilled cast iron has been used due to its low elongation values for parts that are so strongly impacted because of Risk of breakage considered unsuitable, not to mention the supposedly expensive one Machining such hard surfaces. In contrast, the applicant has recognized that the solid chilled cast alloys on which this application is based s ehi'wohl and mit Advantage for camshafts and rocker arms can be applied.

In particular, it was found that solid chilled cast parts of the above Type also on parts of the same type, both with full and partial lubrication Un track run and let move under load, eating oline and one too strong to allow uneven wear of the two mating parts. Solid chilled cast iron excellent emergency running properties. Also the wear resistance of solid chilled cast iron Consistent from the surface to the end, in contrast to thin surface protection layers; this enables greater depth of wear.

A particular advantage of the proposed reduction in wear (full chilled cast iron: full chilled cast iron) exists when using white solidifying, annealable and re-hardenable alloys in that the camshafts and rocker arms cast therefrom optionally after the casting Soft annealed and can therefore also be made easily cut with a machining process. So it is possible to have the camshaft with axial bores, cross bores for the oil supply, with threaded holes for inserting plugs, with grooves and surfaces all Way of providing dimensionally accurate, without requiring major expenditure for this processing. After finishing, the parts can hardened again and can be traced back to their early hardness value and wear resistance.

Special surface protection processes, such as surface hardening or Spraying on, welding on, soldering on of hard metal plates in the print scene, etc. are omitted including the related costs, as well as previous locking.

Rather, the camshaft and rocker arm work in their normal state of hardness immediately good together.

The beaten, consistently white solidifying, appropriately annealed and hardenable solid chilled cast alloys for camshafts and rocker arms a structure with the following components: a) Austenite and its transformation products (Martensite, troostite, bainite, but not perite) and b) carbides on the base Iron carbide, chromium carbide, chromium-iron mixed carbide and / or additional pure carbides or mixed carbides of niobium, vanadium, molybdenum and other carbide formers.

The structure contains a free graphite.

Examples of the composition of alloys according to the invention s 1 nd: 1. Nickel-chromium chill cast iron with 2 - 4.5% carbon, 2 - 6% nickel or 5 - 10 chromium and other alloy components, e.g. B. each less than 10% of M vanadium, molybdenum, Boron, manganese, silicon, phosph or 2. Chromium-chilled cast alloy with 1 - 5% carbon, O - lo 10% manganese 0.5 - 40% chromium and other alloy components with z. B. each individually below 10 °> nickel, molybdenum, boron, vanadium, niobium, Silicon.

The hardness of the Vollhartgußteilo according to the invention in the installed state should 400 - 800 Hv1 should be more than 650 Hv1.

The hardships of the cooperating partners should expediently differ by no more than 200 Vickers units.

The parts according to the invention can also be used without further heat treatment to be used after casting; in this case the surface treatment takes place of the parts cast with a slight oversize essentially by grinding.

Recesses, z. B. grille surfaces or grooves cast or incorporated, which for the reception serve of lubricants.

The bearing of the camshaft can, in turn, be in very hard bearings, that the rocker arms are done on very hard shafts or bolts, creating the additional Advantage of a practical insensitivity to oil pollution is achieved.

Claims (11)

"VALVE CONTROL" (claims) (»valve control for internal combustion engines, consisting of a camshaft and rocker arms moved by this, the latter actuate the valve stems directly or indirectly, characterized in that the camshaft and rocker arms made of solid white, appropriately soft-glowing and re-hardenable solid chilled cast alloys exist. 2. Valve control according to claim 1, characterized in that the The structure of the camshaft and rocker arm consists of a) Austenite and its transformation products, (Martensite, troostite, bainite, but not ferrite) and b) carbides on the base Iron carbide, chromium carbide, chromium-iron mixed carbide and / or additional pure carbides or mixed carbides of niobium, vanadium, molybdenum and other carbide formers. 3. Valve control according to claim 1, characterized in that this consists of a nickel-chroin chill cast with a composition of 2 - 4.5 percent by weight Carbon 2-6 percent by weight nickel 0.5-10 percent by weight chromium and optionally further alloy components z. B. niobium, vanadium, molybdenum, boron, silicon each individually less than 10 ¼. 4. Valve control according to claim 1, characterized in that this Chilled chrome cast iron has a composition of 1 - 5 percent by weight of carbon 0 - 10 percent by weight manganese 0.5 - 40 percent by weight chromium and other alloy components z. B. niobium, vanadium, molybdenum, boron, silicon or nickel of each individually less than lo, 0. 5. Valve control according to claim 1, characterized in that both the camshaft and the rocker arm made of solid chilled cast iron with a Vickers hardness of koo - Soo HV10 suitably consist of 650 HV10. 6. Valve control according to claim 1, characterized in that the Hardening of the two partners working together, namely camshaft and rocker arm differ by no more than 200 Vickers units. 7. Valve control according to claim 1, characterized in that the camshaft and / or rocker arm made of solid hard cast iron (without subsequent noise treatment) exist # 8. Valve control according to claim 1, characterized in that the camshaft and rocker arms made of the same solid chilled cast iron that solidifies white throughout or from similar solid chilled cast materials exist. 9. Valve control according to claim 1, characterized in that at least one of the two parts that work together directly in the case of softer materials known quietly edited in whole or in part by cutting, z. B. with ### Longitudinal bores, transverse bores, slots, threaded holes, grooves or the like. Provided is. 10. Valve control according to claim 1, characterized in that on the pressure surfaces of the camshaft and / or rocker arm recesses for receiving Lubricants are arranged. 11. Valve control according to claim 1, characterized in that the Storage of the camshaft in very hard bearings and / or those of the rocker arms takes place on very hard bolts.