Floating valve seat inductor

A floating inductor assembly for use in heating a generally conical valve seat formed concentrically around a central bore in an engine component, wherein the assembly is adapted to be moved toward and away from the valve seat by a selectively movable element. This floating inductor assembly comprises a carrier, an inductor having a shape generally matching the valve seat and mounted on the carrier, an aligning nose member extending from the carrier in a given direction and generally concentric with the inductor, and first and second flange portions supported on the carrier and extending radially outwardly in a direction perpendicular to the given direction of the nose member, whereby each flange portion is adapted to engage a coupling member for supporting the assembly onto the movable element in a manner to allow floating in the radial direction only.

This invention relates to the art of inductively heating valve seats and 
more particularly to a floating valve seat inductor assembly to be used in 
inductively heating valve seats. 
INCORPORATION BY REFERENCE 
A floating valve seat inductor of the general type to which the present 
invention is directed is disclosed and claimed in prior U.S. Pat. No. Re. 
29,046. This patent is incorporated by reference herein. 
BACKGROUND OF THE INVENTION 
With the advent of low lead gasoline, it is now common practice to provide 
hardened valve seats in internal combustion engines. In this manner, the 
valve seats have a better wear characteristic and can withstand the 
constant pounding by a poppet valve. This is needed because the 
lubricating effect of lead and phosphorous in the gasoline being consumed 
is no longer available. Several concepts have been used in providing such 
hardened valve seats. One of these is to utilize hardened inserts to 
define the valve seats themselves. Of course, this solution presents 
obvious difficulties in that the valve seats are more expensive and 
require substantially more manufacturing and assembling costs. The most 
common approach is to inductively heat the conical surface forming the 
valve seat of an internal combustion engine by positioning an inductor 
adjacent the seat and directing high frequency currents through the 
inductor. After the inductor has been energized to heat the valve seats 
inductively, the heating operation is discontinued. At that time, the 
valve seat is quenched, generally by mass quenching which results from 
conduction of heat from the valve seat rapidly into the surrounding metal. 
In high production, it is desirable to heat all valve seats at the same 
time for subsequent quench hardening by liquid or mass cooling. 
U.S. Pat. No. Re. 29,046 illustrates a machine for inductively heating 
several valve seats simultaneously. In accordance with the teachings of 
this prior patent, incorporated by reference herein, a plurality of 
floating inductor assemblies are provided in a plurality of housings which 
are movable toward and away from respective valve seats of an engine 
component. Each of the inductor assemblies includes an inductor loop at 
one end of a carrier and a nose concentric with the loop extending toward 
the valve seat. This nose contacts the valve bore in the engine component 
to center the respective inductor carriers with respect to the valve seat 
preparatory to induction heating. This action occurs when the housings 
carrying the respective inductor assemblies are moved toward the valve 
seats. By using the inductor carrier and nose which enter the bore, each 
of the inductor assemblies is centered with respect to the particular 
valve seat to be heated, irrespective of certain manufacturing tolerances 
between adjacent valve seats. 
After the housings move the carriers into the position with the inductors 
concentric with the valve seats, the motion of the housing toward the 
valve seats continues until the inductors actually engage the valve seats. 
Thereafter, the various housings carrying the inductor assemblies are 
locked together and moved in unison away from the engine component a 
distance corresponding to the desired air gap for proper induction 
heating. In this manner, the machine compensates for axial offset of the 
respective valve seats being processed during a given cycle. To allow for 
radial alignment of the respective inductor assemblies with respect to the 
valve seats as the aligning noses enter the valve bore, each of the 
inductor assemblies floats within their respective housings in a manner to 
allow movement only in the radial direction. To accomplish this, a flange 
is provided around the inductor carrier of the inductor assembly. This 
flange is clamped within a companion housing to allow only radial 
movement. During processing of the valve seats, the inductor at the end of 
the inductor assembly is properly positioned in the radial direction and 
in the axial direction for the desired heating of the valve seats. This 
prior machine has been exceedingly successful and is generally used 
throughout the automotive industry. 
As the engines being used in automobiles are reduced in size, the spacing 
between adjacent valve seats to be hardened has been reduced. 
Consequently, the prior housings carrying the floating inductor assemblies 
were too large to allow the desired small spacing between the adjacent 
inductors. This problem was solved in one of two ways. Either the engine 
component was processed twice so that only alternate valve seats were 
hardened during a heating cycle or the floating inductor assemblies were 
machined so that the inductor and nose were offset from the primary axis 
of the total floating inductor assembly. Each of these solutions had 
disadvantages. If the engine component required two cycles for processing 
its valve seats, the production rate was substantially reduced. If offset 
inductor assemblies were provided, it was necessary to provide different 
structures for the inductor assemblies used at adjacent valve seats. 
Consequently, at least twos designs had to be manufactured and stockpiled. 
Also, even with the offset inductors, it was not always possible to 
simultaneously process the valve seats of the head of a relatively small 
engine. 
INVENTION 
The present invention relates to an improvement in the floating inductor 
assembly of the type shown in prior U.S. Pat. No. Re. 29,046, which 
invention overcomes the disadvantages experienced when the valve seats to 
be inductively heated for subsequent quenching are relatively close 
together. 
In accordance with the present invention, the floating inductor assembly of 
the type described above is provided with an elongated flange having two 
spaced flange portions, each of which is clamped in the movable member. 
This movable member forms a housing for the floating inductor assembly. By 
providing coupling structures at the two ends of the elongated flange, the 
inductor assembly can float in a radial direction as the housing or 
movable element is moved with the nose member of the inductor assembly 
entering the bore for centering the assembly with respect to the valve 
seat to be heated. By providing the elongated flange or equivalent 
structure and two spaced coupling members on opposite sides of the 
inductor assembly, the surrounding housing for the inductor assembly can 
be generally rectangular in cross-section with a dimension in the lateral 
direction substantially less than the dimension in the vertical direction. 
Thus, two such housings can be closely spaced with respect to each other 
in a transverse direction. This allows use of the concept of a floating 
valve seat inductor assembly when the valve seats are closely spaced. The 
housing for the inductor assembly has an internal cavity which is larger 
than the flange in all directions so that the flange can move within the 
housing in any direction radially of the inductor. 
In accordance with another aspect of the present invention, the valve seat 
inductor assembly is provided with an arrangement for adjusting the 
angular position of its elongated flange with respect to the inductor loop 
located at the end of the assembly. As is well known, the inductor loop 
includes a circumferentially located gap which allows current to flow in a 
path around the loop. This gap should not be opposite to an area of the 
valve seat adjacent a high mass portion of the engine component. Thus, 
there is provided in accordance with an aspect of the invention, a 
structure for adjusting the angular position of the gap forming the 
inductor loop. By providing an elongated housing with the separating gap 
of the loop at one side, adjacent housings can be reversed in a vertical 
or elongated sense. Consequently, the needed gap can be located on either 
transverse side of the supporting housing according to which flange 
portion is extended upwardly. This ability to shift the gap from one side 
of the assembly to the other by reversing the assembly position together 
with the ability to adjust slightly the specific angular position of the 
gap gives wide latitude in positioning the gap or space in the loop with 
respect to the circumference of a valve seat being hardened. 
In accordance with the present invention, there is provided a novel 
floating inductor assembly as previously described which floating inductor 
assembly includes an arrangement for adjusting the position of the input 
gap in the inductor loop with respect to the housing which carries the 
inductor assembly. In addition, the present invention relates to an 
improvement in the combination of the floating inductor assembly and 
housing for supporting the same in a machine, wherein the housing is moved 
toward the valve seat into a heating position and away from the valve seat 
into a loading position. In accordance with this improvement, the mounting 
means between the assembly and the housing includes first and second 
flange portions supported on the inductor assembly carrier. These flange 
portions extend radially outwardly in a direction generally perpendicular 
to the axis of movement of the housing toward and away from the valve 
seat. In accordance with this improvement, there is provided a first 
coupling means for coupling the first flange portion onto the movable 
housing and a second coupling means for coupling the second flange portion 
onto the movable housing. These first and second coupling means are 
generally in diametrically opposed relationship with respect to the moving 
axis of the housing and the inductor assembly carried thereby. Radial 
movement of the floating inductor assembly with respect to its housing is 
accomplished by including an arrangement in the coupling means for 
allowing only radial movement of the flange portions with respect to the 
housing. In this manner, the housing may have a lateral dimension 
substantially less than the vertical dimension when the two spaced 
coupling means are vertically aligned on opposite sides of the inductor 
carrier. Consequently, the housings are relatively narrow in a vertical 
direction with the two spaced coupling means allowing radial displacement 
being vertically above and vertically below the moving axis for the 
assembly. Adjacent housings can thus be close together without requiring 
geometrical shapes for each of two closely adjacent housings. 
Consequently, even though the valve seats are closely spaced with respect 
to each other, all valve seats can be inductively heated in a single cycle 
by using the present invention and without using a special configuration 
for each of the two closely adjacent assemblies. 
The primary object of the present invention is the provision of a floating 
inductor assembly for use in inductively heating valve seats, preparatory 
to quench hardening the seats, which inductor assembly has a radial 
guiding means that reduces the required transverse dimension of the unit 
or housing carrying the inductor assembly. 
Another object of the present invention is the provision of a floating 
inductor assembly, as defined above, which assembly allows the use of a 
pair of floating assemblies in closely spaced transverse relationship to 
inductively heat adjacent valve seats simultaneously. 
Still a further object of the present invention is the provision of a 
floating inductor assembly, as defined above, which assembly allows 
simultaneous heating of adjacent valve seats in engine components for use 
with relatively small engines wherein the spacing between the valve seats 
is relatively small. 
Another object of the present invention is the provision of a floating 
inductor assembly, as defined above, which assembly allows easy coupling 
with a supporting housing used to move the assembly into and from the 
heating position. 
A further object of the invention is the provision of a floating inductor 
assembly movable by a housing or other support element toward and away 
from a valve seat, which inductor assembly includes an inductor loop 
generally concentric to both the valve seat and the body of the assembly 
and which can be used for any of several different valve seats in an 
engine component. 
Yet another object of the present invention is the provision of the 
combination of a floating inductor assembly and a housing therefor, which 
combination has a relatively small transverse dimension when compared to 
the vertical dimension. These dimensions are controlled by the geometry of 
the coupling structure used to couple the inductor assembly in a radial 
floating manner on the movable housing. 
Still a further object and advantage of the present invention will become 
apparent from the following description, taken together with the 
accompanying drawings.

PREFERRED EMBODIMENT 
Referring now to the figures wherein the showings are for the purpose of 
illustrating a preferred embodiment only and not for the purpose of 
limiting same, FIGS. 1 and 2 show a machine or apparatus A which coacts 
with an engine component B supported opposite thereto for inductively 
heating the generally conical valve seats C of the engine component. In 
accordance with standard practice, each of the valve seats has a 
concentric bore D into which the stem of a poppet valve fits during 
operation of the engine. Since the present invention relates to an 
improvement in the apparatus described in U.S. Pat. No. Re. 29,046, which 
patent is incorporated by reference herein, machine or apparatus A will be 
described only briefly. This apparatus includes a frame 10 movable on a 
base 12 and adapted to carry a plurality of locking and journal blocks 14 
so that the blocks move in unison with frame 10 as it is reciprocated 
between the heating and loading positions. Extending outwardly from each 
block 14 there is provided a housing or movable element 20 supported onto 
a tube 22 which is slidably received within a block 14. The block includes 
a locking arrangement for locking tubes 22 with respect to blocks 14 and, 
thus, frame 10 when desired. Around each tube 22 there is provided a coil 
spring 24 which bias housings 20 outwardly from blocks 14 toward engine 
component B. In accordance with known practice, the amount of outward 
movement of housing 20 is restricted by structure within the blocks 14 
which is not shown. The locking arrangement within the blocks is not shown 
since it does not form a part of the present invention and is clearly 
illustrated in the prior U.S. Pat. No. Re. 29,046. Within each housing 20 
there is a floating inductor assembly F having an outwardly facing 
inductor loop 30 with an outwardly extending centering nose member 32. 
Extending in the opposite direction are tubular inlet leads 34 which will 
be described in more detail and which are also shown in the prior United 
States Letters Patent. Inductor loop 30 is adapted to be energized when 
adjacent a valve seat C for the purpose of inductively heating the valve 
seat. After inductor loop 30 is de-energized, the mass surrounding the 
valve seat quenches the valve seat to harden the conical surface thereof. 
This increases the wear characteristics of the valve seat. 
In operation, housings 20 are aligned with respective valve seats C of 
engine component B, as shown in FIG. 1. Frame 10 is moved into a retracted 
position, generally shown in FIG. 2A, and springs 24 force housings 20 in 
a forward or extended direction to a position which will allow loading of 
an engine component B in front of machine A. Thereafter, as shown in FIG. 
2B, frame 10 is moved toward engine component B. This moves all of the 
locking and journal blocks 14 carrying housings 20 which are reciprocally 
mounted on the blocks. When nose 32 engages bore D, inductor loop 30 is 
centered with respect to valve seat C. After this centering action, which 
generally involves slight radial shifting of assembly F and is shown in 
FIG. 2B, is accomplished, frame 10 moves further in the forward direction 
until all of the inductor loops engage their respective valve seats. This 
is also shown in FIG. 2B. Thus, irrespective of the axial displacement of 
adjacent valve seats, springs 24 allow proper positioning of the inductor 
loops in contact with the respective valve seats. In this position, 
locking blocks 14 lock all tubes 22 with respect to the blocks and, thus, 
with respect to common frame 10. Thereafter, frame 10 is retracted, as 
shown in FIG. 2C, a distance corresponding to the desired air gap between 
the inductor loops and the valve seats. Consequently, all inductor loops 
are moved away from the valve seats a distance necessary to provide a 
desired, preselected air gap. This gap is illustrated as 0.040 inches in 
FIG. 2C. In this slightly retracted, intermediate position, all inductor 
loops are energized for inductively heating the valve seats. Thereafter, 
the inductor loops are de-energized for quenching of the valve seats. The 
heating time, frequency and power level determine the amount and depth of 
heating. Following heating, frame 10 is retracted on base 12 to a loading 
position and the supporting tubes 22 are released for again projecting 
housings 20 into a forward position for subsequent operation as described. 
As can be seen, the floating inductor assemblies F must move radially to 
compensate for any radial misalignment between the centered position of 
assembly F and the actual position of a valve seat to be hardened. In 
practice, bore D and valve seat C are machined in a fixed relationship and 
generally in unison; therefore, by engaging bore D and shifting inductor 
assembly F with respect to this bore, loop 30, which is concentric with 
nose 32, is moved into a concentric position with respect to seat C. The 
present invention relates to an improvement in a mechanism for mounting 
assembly F in housing 20 and for allowing this radial movement of floating 
inductor assembly F with respect to the housing. A device constructed in 
accordance with the invention does not require a substantial transverse 
dimension for housing 20. The transverse dimension means a dimension in a 
direction extending between the valve seats as shown in FIG. 1. 
In accordance with the present invention there is provided an improvement 
in the structure of the floating inductor assembly F. Since all of these 
assemblies are identical, only one assembly will be described in detail 
and this description will apply equally to all inductor assemblies F. 
Referring now to FIG. 3, a carrier 60 machined from an insulating material 
includes a forwardly facing recess 62 into which is adhesively secured a 
plug 64 also formed from an insulation material. Inductor loop 30 is a 
hollow conductor and is held between plug 64 and carrier 60. Carrier 60 
includes an outwardly facing conical portion onto the end of which is 
mounted the previously discussed centering nose member 32. This member has 
an enlarged support shoulder 32a abutting the end of plug 64, a 
cylindrical body portion 32b, which is concentric with axis x, and a 
tapered point 32c which allows insertion of nose member 32 into bore D. 
The tubular inlet leads 34 are formed as hollow tubes 70 and 72, each of 
which forms an electrical connection for loop 30. An outer insulator 
sleeve 74 is provided on tube 70 and insulation sleeve 76 is provided 
between tubes 70, 72. Tubes 70, 72 are connected to leads 80, 82, 
respectively, at an input gap 90 of generally circular loop 30. Coolant 
lines 100, 102 direct coolant through tubes 70, 72 and leads 80, 82 for 
circulation of a coolant through loop 30. Electrical connections 110, 112 
are connected across an appropriate power supply and are connected 
electrically to tubes 70, 72 for completing the electrical circuit through 
loop 30. Thus, when energizing connections 110, 112 alternating current is 
directed through loop 30. This alternating current, in practice, is radio 
frequency and has a power level to provide the desired heating temperature 
and pattern in a valve seat. 
Onto carrier 60 there is secured a rectangular flange 140 having 
diametrically opposed flange portions 142, 144 extending radially 
outwardly from axis x. To fix the flange onto the carrier there is 
provided a coupling arrangement, best shown in FIGS. 5 and 6. In this 
structure, a sleeve 150 has a stop shoulder 152 and an outwardly facing 
cylindrical surface 150a defining a protrusion which enters into a recess 
154 of carrier 60. During assembly, a pin 156 is forced through an opening 
in the outer surface of carrier 60 and into a bore within the metal sleeve 
150. This pin locks sleeve 150 onto carrier 60 into a position where it 
can be assembled by an adhesive. Flange 140 includes a central cylindrical 
bore 160 surrounding surface 152a and fixedly held to sleeve 150 by a set 
screw 170 having an inwardly directed pin 170a. This pin is adapted to 
enter one of several angularly spaced bores 180 in sleeve 150. Any number 
of bores could be provided; however, three bores are illustrated. In this 
manner, the relative position of the flange portions 142, 144 with respect 
to loop 30 can be adjusted slightly for a purpose to be explained in more 
detail with respect to FIGS. 7 and 8. Rectangular flange 140 is assembled 
onto and becomes a part of the floating inductor assembly F by the 
structure so far explained. 
Rectangular flange 140 is supported within housing 20 by spaced rectangular 
plates 200, 202 between which extends a rectangular wall 204. Peripheral 
bolts 206 clamp plates 200, 202 together to capture flange portions 142, 
144 within housing 20. As previously mentioned, the coupling between 
housing 20 and floating inductor assembly F allows only radial movement 
between these two assembled components. To accomplish this, thrust units 
220, 222, 224 and 226 are provided which firmly grip flange portions 142, 
144 in a manner to allow only radial displacement of the total inductor 
assembly F with respect to the housing 20, which housing is reciprocated 
to and from the valve seat as previously described. Connections 100, 102 
and 110, 112, as shown in FIG. 3, are movable slightly to allow for this 
radial displacement of the floating inductor assembly with respect to the 
housing 20, which housing is fixed in block 14 in a radial direction with 
respect to axis x of assembly F. Thrust units 220, 222, 224, 226 are 
formed in pairs and are located at the diametrically opposed flange 
portions 142, 144 to define a relatively small transverse distance which 
is used for controlling the radial movement of assembly F. Each of the 
thrust units includes spaced rings 230, 232 which define facing flat 
surfaces between which are located a circular array of ball bearings 240. 
These bearings are held together by an appropriate ball retainer 234, 
shown in FIG. 4. The clamping action between plates 200, 202 exerts thrust 
between rings 230, 232, the former of which is supported on a rectangular 
plate and the latter of which is fixed onto flange 140, as best shown in 
FIGS. 3 and 4. In this manner, movement of the flange can take place in a 
radial direction as determined by the force exerted on nose 32 as it 
enters bore D during movement of frame 10 in the direction shown in FIG. 
2B. Sufficient clamping pressure is exerted onto the thrust units to 
prevent tilting of flange 140 during centering of loop 30 with respect to 
valve seat C. To support rings 230 of units 222, 226, there are provided 
circular bosses 250. A cam insert 252 supports the other two rings 230 and 
also provides a generally conical cam recess 252a into which a cam 
follower assembly 260 is forced to center both flange portions 142 and 144 
with respect to housing 20. A variety of cam followers could be provided; 
however, cam follower assembly 260 includes an outer cylindrical surface 
to locate rings 232 onto flange 140. This function is provided by a hollow 
retainer 262 extending in opposite directions from flange 140 and adapted 
to receive an internal plunger 264 having a ball follower 266 which is 
forced toward cam recess 252a by an appropriate spring 268. For the 
purpose of compensating for tolerances and for adjusting the position of 
inductor 30 in an axial direction, insert 252 has a threaded shank 252b 
received in plate 200. Set screw 270 locks the insert in a position 
adjusted by an Allen wrench in recess 252c. A clearance opening 272 is 
provided at the forward end of housing 20 to allow slight radial movement 
of inductor assembly F during the centering action. An appropriate O-ring 
seal 280 is provided around the clearance opening to prevent ingress of 
deleterious material into the interior of housing or movable element 20. 
As can be seen, the use of a rectangular flange 140 allows the use of 
relatively small, standard ball bearing rings for thrust elements in the 
assembly. Also any adjustment of pressure can be done by using adjustable 
inserts 252. Housing 20 includes an internal generally rectangular cavity 
290, best shown in FIG. 4. The periphery of this cavity is only slightly 
larger than the periphery of flange 140 to allow slight radial movement of 
the flange within the housing. 
Referring now more particularly to FIG. 4, it is noted that the use of 
diametrically opposed flange portions 142, 144 allows support of floating 
inductor assembly F without requiring a relatively large transverse 
dimension b for housing 20. This dimension is dictated primarily by the 
transverse width a of the thrust units 222-226 and the width of flange 
portions 142, 144 needed to coact with these units. This dimension a is 
substantially less than the vertical height c of housing 20. In practice, 
the thickness or transverse dimension b is less than 7.5 cm when the 
height of housing 20 is greater than 10 cm. The clearance in cavity 290 
for flange 140 is such that balls 240 stay on their supporting rings and 
the cam and followers on portions 142, 144 remain in active engagement. 
This dimension is selected to accommodate the largest axial misalignment 
of a valve seat with an assembly F. 
By providing the support arrangements in the vertical position and not in 
the transverse position, a relatively narrow housing can be provided. This 
then allows two housings to be moved close together as shown in FIG. 1 to 
accommodate closely spaced valve seats in an engine component B. Also, 
only one design is necessary. It is not required that two floating 
inductor assemblies be provided, one for a right hand valve seat and the 
other for an adjacent left hand valve seat in a pair of seats. As shown in 
FIGS. 7 and 8, adjacent valve seats can be processed by reversing the 
position of the flange portions 142, 144. In this manner, the gaps 90 of 
inductor loops 30, which are on a side of assembly F, face in opposite 
directions, which relationship is desired in inductively heating two 
adjacent valve seats in a pair. By providing the set screw 170 and 
companion angularly disposed bores 180, gaps 90 can be adjusted slightly 
with respect to the vertical position of flange 140. In this manner, the 
gaps can be moved to desired circumferential positions in a valve seat 
being heated during set up of the machine A. By providing the gap 90 on 
the side of an assembly F, a right and left heating unit can be created 
only by inverting assembly F in its housing 20. Thereafter, slight angular 
adjustments can be made by turning flange 140 on carrier 60. 
In practice 202 and wall 204 are formed as a unit.