US 3686459 A
In an induction heating device for inductively heating adjacent, first and second generally conical surfaces having generally parallel axes, which device includes at least two inductor units each having a secondary for energizing an inductor thereon, there is provided a common primary surrounding both secondary windings to allow heating of the closely spaced conical surfaces.
Claims available in
Description (OCR text may contain errors)
United States Patent Lewis 1 1 Aug. 22, 1972  MULTIPLE INDUCTOR UNIT FOR INDUCTION HEAT DEVICE  Inventor: John C. Lewis, Hamilton, Ontario,
Canada  Assignee: Park-Ohio Industries, Inc., Cleveland, Ohio  Filed: Oct. 20, 1971  Appl. No.: 190,965
 US. Cl. ..219/l0.57, 219/1075, 219/1079  Int. Cl. ..H05b 9/02  Field of Search..2l9/l0.41, 10.43, 10.57, 10.75,
 References Cited UNITED STATES PATENTS 2,828,397 3/1958 Emerson ..219/l0.79 X
McCorry ..2l9/10.79 X Hogel et a1 ..219/l0.73 X
Primary Examiner.l. V. Truhe Assistant Examiner-B. A. Reynolds Att0rney-Meyer, Tilberry & Body ABSTRACT windings to allow heating of the closely spaced conical surfaces.
5 Claims, 4 Drawing Figures secondary PATENTED M1822 m2 SHEET 1 BF 2 I NVEN TOR.
8 VI E Wm 88m m m L C m. .7 J W PAIENTED M1822 I972 SHEET 2 BF 2 FIG. 2
JOHN C. LEWIS BY Meqm, Mia 1. K 80:14;
ATTORNEYS MULTIPLE INDUCTOR UNIT FOR INDUCTION HEAT DEVICE This invention relates to the art of induction heating, and more particularly to a multiple inductor unit for induction heating device.
The invention is particularly applicable for inductively heating the conical surfaces of two adjacent exhaust valves in the head of an internal combustion engine, and will be described with particular reference thereto; however, it should be appreciated that the invention has much broader applications and may be used for inductively heating a variety of closely spaced surfaces.
In production of an internal combustion engine, the head of the engine generally includes a plurality of intake and exhaust valve seats, which are conical surfaces against which poppet valves close to control the intake and exhaust ports of the engine. With the advent of gasolines having relatively low lead content, it has been found necessary to harden the conical surfaces of the exhaust valve seats so that they. can withstand the high temperatures and repetitive contact with the poppet valves. To accomplish this hardening operation, the most successful approach has been to heat the conical surfaces inductively and then allow air quenching or water quenching thereof. This induction heating operation is generally accomplished by a plurality of closely spaced inductor units, each having an inner single-turn inductor and an outer single-turn secondary winding. Appropriate leads connect the inductor onto the secondary winding, and these components are movable with respect to the exhaust valve seats located in the head of the engine. By providing separate movement for the respective conductor units, the proper magnetic coupling can be obtained for each of the various exhaust valve seats. A multi-tum primary winding was provided around each of the secondary windings of the separate inductor units for inducing a current flow in the secondary winding and, thus, in the inductor of each unit during the induction heating operation. The use of these inductor units has been quite satisfactory;
however, some difficulty has been experienced when the adjacent exhaust valve seats are relatively close together. It has been suggested to offset the inductor on the end of the inductor unit with respect to the axis of the secondary and primary windings to allow the positioning of adjacent inductors relatively close together. This has been satisfactory when the spacing of the valve seats was not too small; however, even when offsetting could be done it presented a substantial ,difficulty because the primary windings became too close to each other. Also, a structure for allowing offset between adjacent inductors beyond the outer dimension of the secondary windings would present structural difficulties and require relatively expensive support for the separate inductors.
All of these disadvantages have been overcome by the present invention which relates to an induction heating device including at least two inductor units for heating adjacent conical surfaces, which device allows relatively close positioning of the inductors without complex offsetting structures for the inductors and by employing the standard structure for securing the inductor onto the inductor unit.
In accordance with the present invention, there is provided an improvement in the structure for heating two adjacent exhaust valve seats, which improvement involves the use of a single multi-tum primary winding.
for two adjacent inductor units including their own secondary windings. Consequently, the single primary winding is inductively coupled to two single-turn secondaries for energizing two separate inductors connected to the secondaries. In this manner, the two secondaries can be positioned directly adjacent to each other and the inductors connected thereto can be directly below the secondaries and still be closely adjacent to each secondary winding connected thereto, which device employs a single primary winding inductively coupled to both of the secondaries of the respective inductor units.
These and other objects and advantages will become apparent from the following description taken together with the accompanying drawings in which:
FIG. 1 is a side elevational view showing, somewhat schematically, the preferred embodiment of the present invention;
FIG. 2 is a cross-sectional view taken generally along line 22 of FIG. 1;
FIG. 3 is a cross-sectional view taken generally along line 3-3 of FIG. 1; and,
FIG. 4 is a cross-sectional view taken generally along line 4-4 of FIG. 1.
Referring now to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, the figures show an induction heating device A positioned adjacent an internal combustion engine block B having closely adjacent exhaust ports l0, 12 with central axes a, b, respectively, spaced from each other a distance c. Concentric with these axes are conical exhaust valve ports 14, 16, respectively, and guide bores 20, 22, respectively. To heat inductively the adjacent conical valve seats 14, 16, there are provided two inductor units C, D which are essentially identical in structure; therefore, only the inductor unit C will be described in detail, and this description will apply equally to the inductor unit D.
Inductor unit C includes an insulated support structure 30 having a central body 32, an upper portion 34 for supporting a secondary winding, and a lower tip 36. Onto the tip is positioned a nose 38 which extends into, and registers with, bore 20. This registration aligns the inductor unit C for heating of the seat 14 preparatory to subsequent quenching by air, liquid or other appropriate media, not shown. Secured onto the upper secondary supporting portion 34, there is a plate 40. A
translating or moving means 42, taking the form of a hydraulic cylinder having rod 44 secured by a joint 46 onto plate 40, causes selective movement of the plate 40 in a vertical direction generally parallel to axis a. Adjacent to the intersection of body 32 and tip 36 of support structure 30, there is provided an inductor 50, generally conforming to the shape of surface 14 and including two connecting leads 52, 54. These leads are electrically joined onto a single-turn secondary winding 60 having a central axis x, shown to be aligned with rod 44 of moving means 42. The corresponding conductor unit D includes an axis y which is spaced from axis x a distance z, which distance is substantially greater than the distance between the axis a of bore 20 and axis b of bore 22. Axes a, b are concentric with the surfaces 14, 16 and also the inductor 50 on each of the inductor units C, D.
To provide appropriate cooling for the secondary 60 and the inductor 50, the inductor and leads 52, 54 are constructed of the normal hollow inductor type material. Secondary 60 is hollow and is provided with an appropriate circumferentially extending baffle 62 and axially extending baffle 64. These baffles are so arranged that the coolant from an inlet 66 passes, in the manner indicated by the arrows, through a first portion of the secondary 60, through the lead 52, around the inductor 50, through the lead 54, through a second portion of the secondary 60 divided by the partition 64, and, then, through an outlet 68. Of course, the particular manner for cooling the secondary and inductor does not form a part of the invention and the arrangement shown is for the purpose of illustration only. Other cooling arrangements could be employed to cool the secondary 60 and the inductor 50.
As so far described, the moving means 42 moves the inductor 50 between at least two positions. In the first position the inductor 50 is adjacent the surfaces 14, 16 preparatory to heating. In the second position the inductor is substantially spaced from the seat 14 to allow loading and unloading of the head B. In accordance with the present invention, the secondaries 60 of the inductor units C, D are inductively coupled with a single multi-turn primary 70 surrounding the two secondaries and having input leads 72, 74 connected across the output of an RF power supply 76. By employing a single primary for the two secondaries 60, spacing m between the secondaries can be maintained at a relatively low valve only sufficient to prevent accidental contact and arcing between the two secondaries. In this manner, the spacing between the inductors 50 can be substantially less than the spacing heretofore possible in this type of apparatus. In addition, by off-setting the inductors 50, 52 from the axes x, y, as shown in FIG. 1, these two inductors can be located with a spacing which generally corresponds to spacing of the secondaries 60, i.e., spacing m. The coupling between the primary and secondary is somewhat less than that which could be accomplished by employing a separate primary for each secondary; however, appropriate adjustments can be made in the input circuits for the primary to compensate for this reduction in the inductive coupling between the primary and secondary.
Having thus described my invention, I claim:
1. In an induction heating device for inductively heating adjacent, first and second generally conical surfaces having generally parallel axes, said device comrising: a first inductor unit for inductively heatin said rrst surface; a second inductor unrt for rnduc rvely heating said second unit; each of said units including an inductor generally matching its respective surface, means for supporting said inductor,- a transformer secondary electrically connected to said inductor and carried by said support means, and means for moving said support means in a direction generally parallel with said surface axis between a first position with said inductor substantially spaced from said respective surface and a second position with said inductor adjacent to its respective surface; and means for inducing current flow into said transformer secondary, the improvement comprising: said current inducing means includes a single multi-tum primary winding surrounding both of said transformer secondaries of said first and second inductor units.
2. The improvement as defined in claim 1 wherein said secondaries of said first and said second inductor units are single turn secondaries.
3. The improvement as defined in claim 1 wherein said secondaries each include a central axis generally parallel to said surface axes and said secondary axes are spaced from each other a distance substantially greater than said spacing of said surface axes.
4. An induction heating device for heating two spaced portions of a workpiece, said device comprising: a first inductor unit including a first inductor adapted to heat the first of said portions and a first secondary winding connected to said first inductor, I
wherein said, first and second inductors have axesspaced from each other a distance less than the spacing between said first and said second central axes.