Self locking valve seat insert

Description

[0001] The present invention relates to valve seats and particularly to self locking valve seats for use in internal combustion engines.

[0002] It has been common knowledge in the art that successful performance of a valve seat insert requires that there be intimate contact with the surrounding engine material so that adequate heat transfer may occur between the insert and the engine.

[0003] The problems of heat transfer is also involved with the problem of securely fastening the valve seat insert in the cylinder head of the engine.

[0004] As a means to improve the economy of the Otto type intemal combustion engine, auto manufacturers have attempted to switch from cast iron to aluminum block and/or aluminum head engines. This switch has accentuated the problems associated with heat transfer and securely fastening valve seats in the cylinder heads.

[0005] A number of solutions have been tried in the past with limited success. Valve seats which are pressed into counterbores and then locked in place with various devices have been used. These have not proved entirely satisfactory. because of heat transfer problems, resulting from the build up of corrosion and carbon deposits around the insert and its fastening device.

[0006] Self tapping threads have been used on valve seat inserts as in U.S. 3,868,953 to overcome heat transfer and secure fastening problems. While partially solving those problems this method has introduced new problems of alignment and cost of manufacture. Furthermore, replacement of the insert with the self-cutting thread sometimes results in a loose valve seat since the new insert may not fit tightly into the threadways formed by the previously used valve seat insert.

[0007] The method current used for insertion of valve seat inserts is to lower the temperature of a machined insert by immersion in liquid nitrogen. Then heat the cylinder head to expand the machined opening and then force the insert into the opening.

[0008] When the insert and cylinder head reach ambient temperature a tight fit results with good heat transfer characteristics. However, this method is expensive since it involves rigid manufacturing tolerances and the use of cryogenic equipment and the handling of liquid nitrogen. There is also a safety hazard involved in handling liquid nitrogen as part of a large production scale operation.

[0009] Also, while this cryogenic procedure has proved satisfactory for initial engine production operations, it does not solve the problem of replacing valve seats in the field.

[0010] It is an object therefore of this invention to provide a simple economical valve seat insert capable of easy, inexpensive insertion in cylinder heads of intemal combustion engines.

[0011] It is an object of this invention to provide a valve seat insert, which is self locking into intimate contact with the surrounding material of the cylinder head.

[0012] It is still another object of this invention to provide a valve seat insert with improved heat ' transfer characteristics.

[0013] It is a further object of this invention to provide a self locking valve seat insert that can be removed and replaced in the field with common tools available at most service garages.

[0014] The present invention accomplishes these objects and others by providing a valve seat insert with a pilot flange to guide the insert into a. prebored hole in the cylinder head into which it snugly fits. A locking flange is provided of greater diameter than the pilot flange and the prebored hole. The locking flange contains longitudinal serrations around the circumference thereof and a forming edge. One shoulder of the locking flange and a shoulder of the pilot flange. define an annular groove into which displaced metal is packed.

[0015] When the valve seat insert is forced into the cylinder head the forming edge of the shoulder of the locking flange swages metal from the sides of the prebored hole, packing the displaced metal into the annular groove preventing axial movement of the insert when in place. The serrations around the circumference cut grooves into the walls of the cylinder head and are locked into intimate contact with the cylinder head in these grooves, preventing rotational movement and insuring maximum heat transfer between the valve seat insert and the cylinder head.

[0016] In those instances in which rotational movement is not a problem or in which the rotational forces are minimal, the serrations may be omitted from the locking flange. In that mode (not'illustrated) the locking flange shoulder by swaging metal into the annular groove forms a metal to metal lock preventing axial movement and resisting rotational movement.

[0017] From the following description taken in conjunction with the accompanying drawings, the objects, features and advantages of this invention will become apparent.

Fig. 1 is a partial cross-section side plan view of the self locking valve seat insert.

Fig. 2 is a top plan view of the self locking valve seat insert.

Fig. 3 is a partially sectioned view of a cylinder head with a setf. tocking valve seat insert in place.

[0018] Referring now to the drawings for an understanding of the invention, particularly to the embodiment in Fig. 1 and 2. A cylindrical ring 10 has a valve seat 19 formed in its upper face 16. Pilot flange 11 designed to guide the ring 10 into a prebored hole in cylinder head 20, is formed in the lower portion of ring 10.

[0019] Lead edge 12 is beveled towards the lower face 17 to facilitate entry into the prebored hole. A locking flange 13 greater in diameter than pilot flange 11 has a forming shoulder 14- opposite the valve seat face, the purpose of which will be clearly described below.

[0020] The circumference of locking flange 13 is processed to form longitudinal serrations 18. Between pilot flange 11 and locking flange 13 an annular groove 15 is formed by the shoulders of the two flanges. The self locking valve seat insert is installed by first drilling a straight sided hole in the cylinder head 20 with a diameter adapted to snugly accept the pilot flange 11. Fitting 10 is placed above the prebored hole. Pilot flange 11 is inserted in the hole. Insertion pressure is then applied to valve seat face 16. Forming shoulder 14 displaces metal which flows into annular groove 15 forming a metal ring in the groove. Serrations 18 cut cooperating grooves in cylinder head 20 locking the valve seat 10 in place preventing radial movement. The metal displaced from the cylinder head 20 is packed into annular groove 1 b torming a metal ring in the groove and resulting in a metal to metal lock holding the fitting into position and preventing axial movement outward. Valve seats utilizing the device of this invention have resisted push out forces in excess of about 70,000 N (15,000 pounds) which exceeds operating engine pressures,

[0021] Thus it can be seen that the above device, although simple in construction, fills a long established need and surprisingly provides a positively metal to metal lock resistant to high push out pressures. The metal to metal lock also assures efficient heat transfer from valve seat to cylinder wall. The above described self locking valve seat insert can be easily replaced in the event of valve seat failure. The defective valve seat insert 10 is pushed out. A new self locking valve seat insert with longer serrations 18 is then pressed in place to a depth greater by the increased length of the serrations 18. This will provide sufficient metal flow to pack in said groove 15 to lock the valve seat insert in place so as to resist axial push out. The serrations 18 will mesh with the preformed grooves preventing radial movement. The tight metal to metal lock will ensure excellent heat transfer between the valve seat insert and the cylinder head.

[0022] While only one embodiment of the invention has been shown and described in detail it is apparent that the invention may be incorporated into valve seat inserts having various different forms and sizes.

[0023] Under certain operating conditions where reduced rotational stress is placed upon the guide or in which rotational movement is not objectional, the serrations may be omitted from the locking flange. In those instances (not illustrated) the locking flange forming shoulder 14 is of appropriate diameter to flow the proper amount of material from cylinder head 20 so as to pack annular groove 15 with sufficient material so as to form a metal ring in the groove and resulting in a metal to metal lock which prevents axial movement and resists rotational movement.

[0024] In the preferred embodiment, furthermore the diameter of said locking flange 13 is not less than 0.125 mm (.005 of an inch) greater and not more than 0.375 mm (.015 of an inch) greater than the diameter of the pilot flange 11.

[0025] It is also apparent to those skilled in the art' that many changes and modifications may be made in the illustrated embodiment without departing from the scope of the invention as described in the claims.

Claims

1. A self locking valve seat insert for installation in an engine cylinder head, consisting of

a substantially cylindrical metal ring having a valve seat (19) on one face (16) thereof; comprising

a pilot flange (11) beveled at the edge (12) forming the face opposite the valve seat (19);

a locking flange (13) greater in diameter than the pilot flange (11 containing the valve seat on its upper face (16) and a forming shoulder (14) at its lower edge:

an annular groove (15) formed by and located between the pilot flange (11) and the locking flange (13); whereby cold formed material is to be displaced from the cylinder head and packed into the annular groove by the forming shoulder to provide a metal to metal lock.

2. The self locking valve seat insert of claim 1 in which the diameter of said locking flange (13) is not less than 0.125 mm (.005 of an inch) greater and not more than 0.375 mm (.015 of an inch) greater than the diameter of the pilot flange (11).

3. The self locking valve seat insert of claim 1 in which the circumference of the locking flange (13) contains longitudinal serrations (18).

Ansprüche

1. Selbstsperrender Ventilsitzeinsatz auf der Basis eines im wesentlichen zylindrischen Metallrings mit einem auf einer Fläche (16) angeordneten Ventilsitz (19) zum einbau in dem Zylinderkopf eines Motors, gekennzeichnet durch die Kombination folgender Merkmale:

die vom Ventilsitz (19) abgelegene Fläche ist von einem an seiner Kante (12) abgeschrägten Vorflansch (11) gebildet;

ein Sperrflansch (13) mit im vergleich zum Durchmesser des Vorflansches (11) grosserem Durchmesser weist an seiner oberen Fläche (16) den Ventilsitz auf und an seiner unteren Kante eine Verformungsschulter (14);

zwischen dem Vorflansch (11) und dem Sperrflansch (13) ist eine Ringnut (151 gelegen und durch diese Flansche (11, 13) gebildet,

so dass kaltverformtes Material aus dem Zylinderkopf durch die Verformungsschulter verlagerbar und in die Ringnut hineinpackbar ist, um einen Metall-Metallgriff zu ergeben.

2. Selbstsperrender VentilsitZ nach Anspruch 1, dadurch gekennzeichnet, dass der Durchmesser des Sperrflansches (13) um nicht weniger als 0,125 mm grösser und um nicht mehr als 0,375 mm kleinergrösser ist als der Durchmesser des Vorflansches (11).

3. Selbstsperrender Ventilsitzeinsatz nach Anspruch 1, dadurch gekennzeichnet, dass die Umfangsfläche des Sperrflansches (13) in Längsrichtung verlaufende Riefen (18) aufweist.

Revendications

1. Pièce rapportée à autoverrouillage formant siège de soupape et destinée à être placée dans la tête de cylindre d'un moteur, et comportant une bague métallique substantiellement cylindrique présentant, sur une face (16), un siège de soupape (19), caractérisée par le fait qu'elle comporte:

un rebord pilote (11) biseauté sur le bord (12) et formant la face opposée au siège de soupape (19);

un rebord de verrouillage (13) de diamètre supérieur à celui du rebord pilote (11 ), comportant le siège de soupape sur sa face supérieure (16) et un épaulement de formage (14) sur son bord inférieur;

une gorge annulaire (15) définie par le rebord pilote (11) et le rebord de verrouillage (13) et située entre ceux-ci; la matière formée à froid étant déplacée à partir de la tête de cylindre et refoulée dans la gorge annulaire par l'épaulement de formage pour fournir un verrouillage métal-métal.

2. Pièce rapportée à autoverrouillage formant siège de soupape selon la revendication 1, caractérisée par le fait que le diamètre dudit rebord de verrouillage (13) est supérieur au diamètre du rebord pilote (11) d'une quantité non inférieure à 0,125 mm (0,005 pouce) et non supérieure à 0,373 mm (0,015 pouce).

3. Pièce rapportée à autoverrouillage formant siège de soupape selon la revendication 1, caractérisée par le fait que le contour extérieur du rebord de verrouillage (13) présente des dentelures longitudinales (18).

Drawing