USRE32520E

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Publication number: USRE32520E
Application number: US06/448,042
Authority: US
Inventors: Melvin A. Lace
Priority date: 1977-11-04
Filing date: 1982-12-08
Publication date: 1987-10-13
Anticipated expiration: 1998-05-19

Abstract

A magnetic probe for sensing the passage of a moving magnetic element, comprising a radially magnetized cylindrical permanent magnet, formed of a flat sheet of elastomer bonded ferrite material magnetized across its smallest dimension and curled to cylindrical configuration, or formed in cup-shaped configuration. A magnetic collector core is mounted co-axially in one end of the magnet cylinder and has an axial pole piece of reduced diameter projecting to the other end of the magnet cylinder, and an electrical sensor coil encompasses the pole piece; the sub-assembly comprising the magnet, the core, and the coil is mounted in a cylindrical magnetic housing, with only high-reluctance flux paths between the inner surface of the permanent magnet and the housing.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No. 849,547, filed Nov. 4, 1977 now abandoned.

BACKGROUND OF THE INVENTION

A magnetic probe, sometimes called a magnetic pickup or magnetic sensor, is a non-contact transducer employed to convert the kinetic energy of a ferromagnetic element moving past the probe into electrical energy. These devices are used in a variety of applications, frequently being employed to sense the movement of gear teeth or similar elements for synchronization and timing purposes. A common construction for a magnetic probe of this general type comprises a permanent magnet of disc or rod shape having a pole piece of reduced diameter projecting coaxially from the disc and an electrical sensing coil mounted on the pole piece. The magnet, pole piece, and coil are usually mounted in a cylindrical housing, though the housing is sometimes omitted.

Magnetic probes are highly advantageous in many applications, as compared with mechanical or optical sensors. There are no switch contacts to wear out, no cables to break, no mechanical couplings subject to failure, no lamps to fail, and no necessity for protection from dirty environments. Magnetic probes are also highly reliable and afford extremely long operating life with little or no maintenance cost.

A magnetic probe of conventional construction, as generally described above and as illustrated in FIG. 1, however, does present some substantial technical problems and difficulties. Thus, some form of non-magnetic housing is a virtual necessity for the probe, because a magnetic housing or other magnetic member in close proximity to the permanent magnet may effectively short-circuit the magnetic sensing field of the device and prevent effective operation. Indeed, magnetic losses in conventional probes are quite high, and it is often difficult to obtain an output signal of adequate amplitude. The mounting of the probe is often critical, particularly if the probe is used in a magnetic environment as in a timing device for an internal combustion engine. For applications of that kind, the probe housing must usually be constructed of stainless steel or other non-magnetic steel, materially increasing the cost of the probe. Furthermore, if located within a substantial magnetic field the conventional probe may be de-magnetized and thus rendered inoperative.

A form of magnetic transducer, which could be used as a probe, is shown in Palazzetti U.S. Pat. No. 3,942,045. One form of the Palazzetti transducer employs a cylindrical permanent magnet, uniformly magnetized in a radial direction, in a magnetic circuit structure that permits the use of a housing formed of steel or other magnetic material, thus avoiding one of the principal problems of the conventional probe discussed above. But this form of the device incorporates magnetic structures of undesirable complexity and cost, and does not provide strong enough output signals when reduced to the size required for some critical applications.

SUMMARY OF THE INVENTION

It is a principal object of the invention, therefore, to provide a new and improved magnetic probe construction that effectively and inherently minimizes or eliminates the problems and difficulties of previously known probes and like transducers as discussed above.

A specific object of the invention is to provide a new and improved magnetic probe that affords a high amplitude signal output without requiring critical adjustment of the probe with respect to the gear teeth or other elements that it senses, employing small, simple components that do not require undue cost or precision in the assembly of the probe.

Another object of the invention is to provide a new and improved magnetic probe construction that exhibits minimal magnetic losses, that is virtually immune to de-magnetization, and that can be quickly assembled from components of simple configuration formed of inexpensive materials by routine manufacturing processes.

A further object of the invention is to provide a new and improved magnetic probe construction that permits the use of a permanent magnet formed from a sheet of flexible elastomer material simply inserted into a tubular housing of ordinary steel, affording a rugged construction at very low cost.

Accordingly, the invention relates to a magnetic probe for sensing the passage of a moving magnetic element. The probe comprises a cylindrical housing of high permeability material, a radially magnetized cylindrical permanent magnet mounted coaxially within the housing and extending inwardly from one end of the housing in circumferential surface-to-surface contact with the housing, a core of high permeability material mounted within and extending axially of the permanent magnet, the core including a small diameter pole piece extending axially inwardly from the one end of the housing and joined to a large diameter magnetic flux collector engaging the interior of the permanent magnet in circumferential surface-to-surface contact at a location spaced from the one end of the housing, and an electrical sensor coil encompassing the pole piece; only high-reluctance flux paths are present between the interior surface of the permanent magnet and the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional elevation view of a magnetic probe of the kind most commonly used in the prior art;

FIG. 2 is a sectional elevation view of a magnetic probe constructed in accordance with one embodiment of the present invention;

FIG. 3 is an end view of the probe of FIG. 2, taken from the sensing end of the probe, before sealing of the probe;

FIG. 4 is a perspective view of a preferred form of permanent magnet used in the probe of FIGS. 2 and 3, prior to assembly with other components of the probe;

FIGS. 5A and 5B illustrate the output waveforms for the probe of FIGS. 2 and 3 for common operating conditions; and

FIGS. 6 and 7 are sectional elevation views of magnetic probes constructed in accordance with two further embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a prior art magnetic probe constuction that is used in a wide variety of applications, including synchronizing devices for internal combustion engines, timing and synchronizing equipment for teleprinters, and many others. The probe 10 shown in FIG. 1 includes a permanent magnet 11 in the form of a thick disc or rod, longitudinally magnetized as indicated in the drawing. A pole piece 12, substantially smaller in diameter than magnet 11, projects coaxially from one end of the magnet. An electrical sensing coil 13 is mounted in encompassing relation to pole piece 12. Magnet 11, pole piece 12, and coil 13 are mounted within a housing or shell 14 which is formed from non-magnetic material to preclude shorting out the magnetic sensing field, which must extend through pole piece 12. Electrical connector leads 16 for coil 13 are brought out to the end of housing 14 opposite pole piece 12. The interior of shell 14 is filled with potting resin 17 to afford a totally sealed probe structure. For effective operation it is usually necessary that the tip of pole piece 12 project slightly beyond the end of shell 14.

The configuration of the magnetic field for probe 10 is generally indicated by dash line 18. When a magnetic element such as a gear tooth 19 approaches the tip of pole piece 12 it disturbs the magnetic field 18 and induces a voltage in coil 13. An output signal from coil 13 is produced each time a gear tooth or other ferromagnetic discontinuity passes the outer end of pole piece 12. The amplitude of the signal from the probe is roughly proportional to the speed of tooth passage and is inversely proportional to the spacing between element 19 and pole piece 12.

The large air gap in the magnetic circuit for probe 10, as generally indicated by field line 18, inherently results in relatively large magnetic losses. Furthermore, it is essential that the gear tooth or other element 19 being sensed approach quite closely to pole piece 12 in order to develop a usable output signal from coil 13. If probe 10 is mounted in a rugged environment it is usually necessary to fabricate housing 14 from stainless steel or other relatively expensive non-magnetic steel. Furthermore, magnet 11 may be subject to de-magnetization if the probe is located in a relatively strong alternating magnetic field as may be encountered in an internal combustion engine or other environments.

FIGS. 2 and 3 illustrate amagnetic probe 30 constructed in accordance with one preferred embodiment of the present invention;probe 30 inherently and effectively overcomes the difficulties and problems associated with conventional probes such as the probe 10 of FIG. 1.Probe 30 comprises acylindrical housing 31 of high permeability material having a threadedexterior surface 32. Preferably,housing 31 is formed of ordinary, inexpensive magnetic steel and may constitute a length of ordinary steel tubing. Thethread 32 is utilized only for mounting purposes and has no effect on the operating characteristics of the probe;housing 31, as shown, can be fabricated at minimum expense, as by means of a screw machine, particularly because the interior of the housing is of uniform diameter throughout its length. Typically, the outside diameter ofhousing 31 may be of the order of 0.625 inch, though substantial variation is permissible.

A radially magnetized cylindricalpermanent magnet 33 is mounted coaxially within the axial bore orchamber 34 inhousing 31. One end ofmagnet 33 is aligned with one end 35 ofhousing 31; the magnet extends inwardly from end 35 ofhousing 31 in circumferential surface-to-surface contact with the inner surface ofbore 34 throughout the length L_m of the magnet.

Acore 36 of high permeability material, preferably ordinary steel, is mounted coaxially within the cylindricalpermanent magnet 33.Core 36 includes a magnetic flux collector portion 37 having an outer diameter approximately equal to the inner diameter ofmagnet 33, so that the exterior of the collector engages the interior of the magnet in surface-to-surface contact throughout the collector length. A reduced-diameter pole piece 38 is a part ofcore 36;pole piece 38 projects from collector portion 37 of the core out to the end 35 ofhousing 31. The collector and pole piece portions ofcore 36 may be formed from a single, unitary piece of steel. Alternatively,pole piece 38 can be mounted incollector 36 by a threadedconnection 37A, usually a more economical construction.

Anelectrical sensor coil 41, preferably wound on aconventional bobbin 42, is mounted in encompassing relation topole piece 38. As shown in FIG. 2, the coil and bobbin preferably have an axial length slightly less than the length ofpole piece 38 so that the coil terminates short of the outer end 35 of the probe. The electrical leads 43 forcoil 41 may be disposed in asmall gap 44 in thecylindrical magnet 33 and extend out through theouter end 39 ofprobe housing 31. On the other hand, the coil wire is usually thin enough andmagnet 33 usually has enough "give" so that leads 43 can be brought out to end 39 of the probe between the magnet and collector 37. In the preferred construction, the interior ofhousing 31 is filled completely with asuitable potting resin 45 to provide a completely sealed probe structure. In some instances it may be desirable to use an electrically conductive resin toground core 36 tohousing 31, or a separate grounding wire (not shown) can be used.

Becausemagnet 33 is uniformly radially magnetized, in the direction in FIGS. 2 and 3, the entire interior of the portion ofchamber 34 encompassed by the magnet appears as a magnetic pole of one polarity, in this instance north polarity. Of course, the opposite polarity can be used. Most of the flux frommagnet 33 is collected by the collector 37 ofcore 36. Accordingly, a strong magnetic field is established betweenhousing 31 andpole piece 38, at the one end ofprobe 30, as generally indicated bydash lines 46. Some magnetic losses are experienced across the high-reluctance "air" gaps present at the opposite ends ofmagnet 33 as generally indicated bydash lines 46A and 46B. However, the magnetic field is much better concentrated at the operating end 35 of the probe than in the case of the prior art constructions described above. Thesupport 51 forprobe 30 can be magnetic or non-magnetic; it makes no significant difference operationally.

In broad general terms, the operation ofprobe 30 is essentially similar to that of previously known probes. A gear tooth or other magnetic element 19 approaching end 35 ofprobe 30 creates a disturbance in themagnetic field 46 which in turn develops an electrical voltage insensor coil 41. The principal magnetic effect is a major reduction in reluctance for theportion 46 of the magnetic field betweenhousing 31 andpole piece 38. A further disturbance is created when the magnetic element 19 leaves the area proximate to the sensor end 35 ofprobe 30, restoring theflux path 46 to its initial high reluctance condition. The waveform for the output signal fromsensor coil 41 for a medium tooth gear 19A corresponds generally to curve 47 of FIG. 5A. For a coarse tooth gear 19B (FIG. 5B) the waveform may be as indicated by curve 48. Other variations in the output signal fromcoil 41 may occur with changes in the size and shape of the magnetic projections 19 being sensed. The waveforms are generally the same as for conventional probes, but the amplitudes are much greater for probes of comparable size.

Probe 30 affords substantial operational advantages as compared with probe 10.Probe 30 is virtually immune to de-magnetization because itspermanent magnet 33 is enclosed in themagnetic housing 31. The magnetic circuit arrangement ofprobe 30 is substantially more efficient than that for previously known probes; for a probe of given size and using the same form of electrical sensor coil, probe produces an output amplitude at least several times greater than probe 10. In fact, the output signal fromprobe 30 is usually at least four to six times greater in amplitude than for a probe 10 of comparable construction. Extension ofmagnet 33 to the outer end 35 ofprobe 30 and beyond the opposite end ofcore 36 is also advantageous in assuring maximum amplitude for the probe output.

The components ofprobe 30 are inexpensive and assembly is extremely simple and economical.Permanent magnet 33 starts as a thin, flat sheet of magnetizable elastomer material (FIG. 4) magnetized through its thickness. The permanent magnet sheet is curled lengthwise and inserted intohousing 31 into the position shown in FIG. 2. A simple jig inserted intoend 39 ofhousing 31 can serve to assure axial alignment of the permanent magnet in the housing. The magnet width W may be made slightly smaller than the inner circumference of thechamber 34 inhousing 31 so that thegap 44 forcoil leasd 43 is formed automatically; the gap may be omitted, if desired.Core 36, withcoil 41 mounted thereon, is then inserted into the position shown in FIG. 2 and the interior ofchamber 34 is subsequently filled with a suitable potting resin. A suitable adhesive can be used to hold the coil, core, and magnet in position prior to potting. Precision assembly tolerances are not required.

In the preferred construction illustrated in FIG. 2, the length L_m ofpermanent magnet 33 is made slightly larger than the total length L_c ofcore 36. Consequently, ashort length 33A ofmagnet 33 projects beyondcore 36 at the end of the core oppositepole piece 38. It has been found that ashort projection 33A, usually of the order of 1/16 to 1/8 inch, depending upon the overall size of the probe, adds materially to the magnetic efficiency of the device.

The magnet length L_m is preferably less than the housing length L_h to assure maximum protection against de-magnetization and physical damage.Magnet 33 may extend to a point flush with housing end 35, as shown, or it can be terminated a small distance short of housing end 35 and covered withresin 45 for further protection. However,magnet 33 should cover all ofcoil 41. Furthermore, it has been found that recessing the magnet to any substantial distance from probe end 35, so that an appreciable length ofhousing 31 faces the outer tip ofpole piece 38 with no magnet between, can lead to an appreciable reduction in output amplitude.

The much preferred construction forpermanent magnet 33 is a flat sheet curled to cylindrical form, as described in connection with FIGS. 2-4; this is by far the simplest and most economical construction, yet is simple and easy to assemble into the probe. Other structural arrangements, however, can be used for the cylindrical permanent magnet. Thus, the permanent magnet can be preformed in two semi-cylindrical elements or even as a complete cylinder if desired, usually at some sacrifice in economy.

In some instances, it may be desirable to utilize some part of the equipment in which the probe is employed as the exterior housing for the probe. A probe sub-assembly can be readily constructed, comprisingmagnet 33,core 36, andcoil 41. In fabricating a sub-assembly of this kind, the permanent magnet, if formed from sheet material as illustrated in FIG. 4, is simply wrapped around the collector portion 37 ofcore 36 and secured thereto by appropriate means such as an epoxy resin. Similar means may be utilized to mountcoil 41 onpole piece 38. For protection, the sub-assembly can then be molded into a suitable resin body to afford a device that can be mounted directly in a working mechanism as generally represented by the mountingwall 51. A sub-assembly of this kind would ordinarily be employed for relatively small probes, of the order of one-quarter inch or less total diameter. A sub-assembly arrangement should be used in an environment in which some external element, such assupport wall 51, is of magnetic material, thus affording a direct substitute forhousing 31.

The high amplitude output of the device makes axial adjustment of the probe position, relative to the sensed magnetic element 19, less critical than for prior art probes. Furthermore, and as shown in FIG. 2,pole piece 38 need not project beyond the end 35 of the remainder of the probe structure. Thus, both initial assembly and subsequent mounting of the probe are less critical forprobe 30 as compared with the prior art.

FIG. 6 illustrates a magnetic probe 60 constructed in accordance with another embodiment of the present invention. Probe 60 comprises a cup-shaped magnetic housing 61 having a closedbase 62 and anopen end 65. Housing 61 need not be of one-piece construction as shown;base 62 can be a simple cap threaded onto or otherwise affixed to the tubular portion of the housing. A cylindricalpermanent magnet 33 is mounted in housing 61 and extends inwardly of the housing from theopen end 65. A cylindricalinternal shell 66 of high permeability material is mounted withinmagnet 33 and thecore 36 of the probe is mounted insideshell 66. The arrangement ofpole piece 38 andcoil 41, on itsbobbin 42, remains the same as for the embodiment of FIG. 2.

A disc-shaped auxiliarypermanent magnet 67, magnetized in an axial direction, is mounted on the end surface of the collector portion 37 ofcore 36opposite pole piece 38.Magnet 67, likemagnet 33, is preferably formed of elastomer-bonded ferrite, though other permanent magnet materials can be used for either. A disc-shaped auxiliary magnetic flux collector 68 of high permeability material may be used to connect theauxiliary magnet 67 to thebase 62 of housing 61, or the housing dimensions may be selected to bring the housing into direct engagement with the outer face of the auxiliary magnet.

Probe 60, FIG. 6, provides the same advantages asprobe 30, FIG. 2, with additional enhancement of the output amplitude.

Permanent magnets

33 and 67 are both magnetized toward the interior of the device so that it is again possible to utilize magnetic material for the outer shell or housing 61. Magnetic losses are even lower than inprobe 30 and precision assembly is again not required. The interior shell orshield 66 has also been found to improve the performance characteristics of a probe like that of FIG. 2 that does not include theauxiliary magnet 67. As in the case ofprobe 30, probe 60 requires only components of simple tubular or rod-like configuration, minimizing manufacturing costs.

FIG. 7 is a sectional elevation view, like FIGS. 2 and 6, of amagnetic probe 70 constructed in accordance with yet another embodiment of the present invention.Probe 70 includes a cup-shaped magnetic housing 71 having a closedbase 72 and anopen end 75.Base 72 is shown as being of integral one-piece construction with the side walls of housing 71 but could be a separate member threaded into or otherwise affixed to the cylinder portion of the housing.

Inprobe 70, there is a cup-shapedpermanent magnet 73 that is mounted within housing 71 and extends inwardly of the housing from theopen end 75. Thepermanent magnet 73 is molded or otherwise formed, preferably as a single piece, from a permanently magnetizable elastomer or resin material. The cylindrical portion ofpermanent magnet 73 is disposed in uniform surface-to-surface contact with the inner surface of the cylindrical portion of housing 71, and thebase 74 ofmagnet 73 engages bothcollector 36 andhousing base 72, again in surface-to-surface contact.Magnet 73 is magnetized in the directions indicated by the arrows in FIG. 7, presenting a uniform polarity throughout its interior surface and a uniform opposite polarity throughout its outer surface. Withinmagnet 73, the arrangement ofcore 36,pole piece 38, andcoil 41, on itsbobbin 42, remains the same as for the previously described embodiments.

Probe 70, FIG. 7, provides the same advantages as the previously describedprobes 30 and 60 of FIGS. 2 and 6, with additional advantages in some instances. Thus, the interior elements of the probe are completely shielded by thepermanent magnet 73, which presents a permanently magnetized surface of the same polarity facing the entire collector, pole piece, and coil structure. The only magnet leakage occurs at theouter end 75 of housing 71, through a single high reluctance air gap around the end ofmagnet 73. Magnetic losses are extremely low. On the other hand, precision assembly is not required; the entire probe 71 can be rapidly assembled simply by inserting the components into the cup-shaped housing 71. As in the previous embodiments, the space aroundcoil 41 and across the face of the probe may be filled with a suitable potting resin to afford a totally sealed construction.

Claims

I claim:

1. A magnetic probe for sensing the passage of a moving magnetic element, comprising:

a cylindrical housing of high permeability material;

a radially magnetized cylindrical permanent magnet mounted co-axially within the housing and extending inwardly from one end of the housing in circumferential surface-to-surface contact with the housing throughout the length of the magnet;

a core of high permeability material mounted within and extending axially of the permanent magnet, the core including a small diameter pole piece extending axially inwardly from the one end of the housing and joined to a large diameter magnetic flux collector engaging the interior of the permanent magnet in circumferential surface-to-surface contact at a location spaced from the one end of the housing;

and an electrical sensor coil encompassing the pole piece;

all flux paths between the inner surface of the permanent magnet and the housing at the opposite ends of the magnet being high-reluctance paths.

2. A magnetic probe according to claim 1 in which the housing is of uniform internal diameter and the permanent magnet comprises a thin, flat sheet of magnetizable elastomer material, having a length L_m less than the length L_h of the housing and having a width W no greater than the inner circumference of the housing, magnetized across its thickness, and curled lengthwise to fit into the housing.

3. A magnetic probe according to claim 2 in which the width W is slightly smaller than the inner housing circumference so that with the probe assembled there is a limited gap in the permanent magnet, affording a passageway for electrical conductors extending from the coil axially along the periphery of the collector to the opposite end of the housing.

4. A magnetic probe according to claim 1, in which the magnet core extends to the outer edge of the one end of the housing.

5. A magnetic probe according to claim 1 and further comprising:

a cylindrical internal shell of high permeability material extending from the collector toward the one end of the housing in surface contact with the interior of the permanent magnet.

6. A magnetic probe according to claim 1 in which the permanent magnet is of cup-shaped configuration, magnetized to afford inner and outer surfaces of uniform opposite polarities, with the base of the cup engaging the flux collector in surface-to-surface relation.

7. A magnetic probe according to claim 6 in which the housing is also of cup-shaped configuration, with the base of the housing engaging the base of the cup-shaped permanent magnet in surface-to-surface relation.

8. A magnetic probe for sensing the passage of a moving magnetic element, comprising:

a cylindrical housing of high permeability material;

a radially magnetized cylindrical permanent magnet, having a length L_m, mounted co-axially within the housing and extending inwardly from one end of the housing in circumferential surface-to-surface contact with the housing;

a core of high permeability material, having a length L_c, mounted within and extending axially of the permanent magnet, the core including a small diameter pole piece extending axially inwardly from the one end of the housing and joined to a large diameter magnetic flux collector engaging the interior of the permanent magnet in circumferential surface-to-surface contact at a location spaced from the one end of the housing;

and an electrical sensor coil encompassing the pole piece;

all flux paths between the inner surface of the permanent magnet and the housing at the opposite ends of the magnet being high-reluctance paths;

and L_m being at least equal to L_c, with the permanent magnet positioned to encompass the full length of the core.

9. A magnetic probe according to claim 8 in which L_m is greater than L_c so that the permanent magnet projects beyond the core at the opposite end of the core from the pole piece.

10. A magnetic probe for sensing the passage of a moving magnetic element, comprising:

a cylindrical housing of high permeability material;

a radially magnetized cylindrical permanent magnet mounted co-axially within the housing and extending inwardly from one end of the housing in circumferential surface-to-surface contact with the housing;

an auxiliary permanent magnet of disc-shaped configuration, magnetized in an axial direction, having one surface engaging the end of the collector opposite the pole piece;

an auxiliary flux collector connecting the opposite surface of the auxiliary magnet to the housing;

and an electrical sensor coil encompassing the pole piece;

all flux paths between the inner surfaces of the permanent magnets, on the one hand, and the housing and the auxiliary collector, on the other hand, at the opposite ends of the probe, being high-reluctance paths. .Iadd.

11. A magnetic pick-up comprising:

an elongated ferromagnetic core which is substantially symmetrical about an axis;

a cylindrical permanent magnet sleeve of bonded permanent magnet material which fits closely around at least a portion of the magnetic core and is substantially co-terminous with one end of the core while not extending substantially beyond the other end of the core, the permanent magnet sleeve being magnetized in a direction radial to the axis of the core;

there being no low reluctance ferromagnetic path directly between the inner and outer surfaces of the permanent magnet sleeve;

and an electrical sensor coil encompassing a portion of the core. .Iaddend. .Iadd.

12. A magnetic pick-up as defined in claim 11 in which the permanent magnet sleeve is substantially co-terminous with both ends of the ferromagnetic core. .Iaddend. .Iadd.13. A magnetic pick-up as defined in claim 11 encapsulated with resin which also encapsulates the leads adjacent the coil. .Iaddend. .Iadd.14. A magnetic pick-up as defined in claim 11 in which the coil does not extend radially outwardly beyond the face of the permanent magnet sleeve. .Iaddend. .Iadd.15. A magnetic pick-up as defined in claim 11 and further comprising a cylindrical housing of ferromagnetic material encompassing the permanent magnet sleeve in circumferential surface-to-surface contact therewith. .Iaddend.