US3749863A

US3749863A - Spring band biased movable contactor for hybrid crash sensor switch

Info

Publication number: US3749863A
Application number: US00214013A
Authority: US
Inventors: H Kaiser
Original assignee: Eaton Corp
Current assignee: ZF Passive Safety Systems US Inc
Priority date: 1971-12-30
Filing date: 1971-12-30
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31
Also published as: JPS4873939A; IT973055B; ES410179A1; DE2263807A1; FR2165923A1; AR199655A1

Abstract

A multidirectional sensor for a passive restraint system for a vehicle. The sensor includes a housing and a mass in the form of a disk located in a cavity defined within the housing. The disk is free to move in the cavity from an initial position to one of a number of actuation positions under the influence of a ''''g'''' force created in a collision situation. The sensor acts as a switch in an electrical circuit. The switch is open when the disk is in the initial position and closed when the disk is in one of the actuation positions. A spring is secured to the disk to retain the disk in the initial position and resist movement of the disk to one of the actuation positions. The spring is designed and arranged so that, in any direction of movement of the disk, the resultant or composite movement of the spring mass is in the same general direction as the movement of the disk so that the time it takes the disk to move to one actuation position is relatively equivalent to the time it takes the disk to move to any other actuation position. In the preferred embodiment, the spring comprises a thin metal band prestressed to wind upon itself; the band is wound around the periphery of the disk with its free end anchored to the housing so that the disk is normally held against a suitable backing surface by the band. In a collision situation, the disc, during movement to an actuation position, rotates and partially unwinds itself from the band.

Description

United States Patent n91 Kaiser [75] Inventor: Hermann Kaiser, Detroit, Mich.

[73] Assignee: Eaton Corporation, Cleveland, Ohio.

[22] Filed: Dec. 30, 1971 21 Appl. No.: 214,013

[52] US. Cl..... 200/6l.45 R, ZOO/61.48, ZOO/ 61.51,

200/166 BA [51] Int. Cl. H01h 35/14 [58] Field of Search 200/8 A, 11 A, 16 C,

200/16 D, 61.45 R, 61.53, 61.44, 61.76,166 BB, 166 BF, 166 BA Primary Examiner-J. R. Scott Attorney.lohn W. Yakimow 1 July 31, 1973 [57] ABSTRACT A multidirectional sensor for a passive restraint system for a vehicle. The sensor includes a housing and a mass in the form of a disk located in a cavity defined within the housing. The disk is free to move in the cavity from an initial position to one of a number of actuation positions under the influence of a g force created in a collision situation. The sensor acts as a switch in an electrical circuit; The switch is open when the disk is in theinitial position and closed whenthedisk is in'one of the actuation positions. A spring is secured to the disk to retain the disk in the initial position and resist movement of the disk to one of the actuation positions. The spring is designed and arranged so that, in any direction of movement of the disk, the resultant or composite movement of the spring mass is in the same general direction as the movement of the disk so that the time it takes the disk to move to one actuation position is relatively equivalent to the time it takes the disk to move to any other actuation position, In the preferred embodiment, the spring comprises a thin metal band prestressed to wind upon itself; the band is wound around the periphery of the disk with its free end anchored to the housing so that the disk is normally held against a suitable backing surface by the band. In a collision situation, the disc, during movement to an actuation position, rotates and partially unwinds itself from the band.

28 Claims, 14 Drawing Figures PATENIEDJUL3 1 ms SHEET l 0F 5 l I mm" Passive restraint devices, such as illustrated in US. Pat. No. 3,414,292, are available for use on vehicles. These devices include a bag which inflates upon the detection by a sensor of a given deceleration force which occurs upon collision of the vehicle with an object. A number of sensors have previously been proposed, e.g., see disclosures in US Pat. No. 3,485,973 (Kaiser); No. 3,489,9l7.(G urol); No. 3,495,675 (I-Iass et al.); No. 3,552,768 (Kaiser); No. 3,556,556 3,571,539 (Kaiser et al.).

The purpose of a crash sensor is to detect when a vehicle has been involved in a collision with another object and to thereupon cause actuation of a device to protect the occupants of the vehicle. If vehicles were involved in purely head on collisions, the problems incurred in designing a crash sensor would be greatly reduced. Since this is not the case, it is desirable to have a crash sensor which will operate in a given manner over a large angular range with a highdegree of confidence. The angular forces which tend to cause a crash sensor to actuate also create secondary forces on certain components, such asthe spring, of certain sensors which cause these components to move .in a manner to resist actuation.-ln order to develop a highly reliable system, it is necessary to remove these undesirable secondary forces on the components of a sensor.

BRIEF SUMMARY OF THE INVENTION According to an important feature of the present invention, these undesirable secondary forces have been eliminated by providing a spring connected to and movable with a disk located in a cavity defined in a housing. The disk is normally situated at an initial position in the cavity and isadapted to move to one of a number of actuation positions upon a change of velocity of the housing. The spring is normally operative to resist movement of the disk from the initial position. During a change of velocity of the housing, the resultant movement of the mass of the spring is in the same general direction as the movement of the mass of the disk from the initial position to anyone of the actuation positions. Since the collision forces act on the spring in the same general manner as the collision forces act on the disk, the effect of the movement of the mass of the spring is additive to the movement of the mass or the disk so that there are no secondary forces acting in a manner to resist actuation.

(Goetz and No.-

coiled metal band prestressed to wind upon itself, e.g.,

a Negator spring manufactured by Hunter Spring, a Division of Ametex Inc. One endofthe spring is wound around the disk and the other end is connected to an electrical contact at the junctionof the angular sides. The contact includes a plurality of electrically conduc-I tive'fin gers. In operation, the described disk-springcontact arrangement becomes an electrical switch which is actuated by the g force that exists during a collision. The exertion of a given g'" force for a given period of time causes the disk to move outward against the force exerted by the band into contact with the fingets and thereby complete an electric circuit, (#i.e., the

BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is a schematic view of a sensor located in an electrical circuit.

FIG. 2 is a perspective view of a sensoraccording to the invention with the sensor cover-removed for clarity. FIG. 3 is a sectional view taken on line 3-3 of FIG. 2, and including the sensor cover. 1

FIG. 4 is a top plan view with the" sensor cover removed illustrating another sensor embodying features of the disclosure. I i A j a FIG. 5 is a sectional view taken on line 5-5 of FIG. 4, and including the sensor cover. FIG. 6 is a top plan view, with the sensor cover removed, illustrating still another sensor embodying features of the disclosure.

FIG. 7 is a sectional view taken on line 7 7 of FIG.

- 6, and including the sensor cover.

FIG. 8is a fragmentary front view of a contact use in the embodiment illustrated in FIG. 6.

FIG 9 schematically illustrates an arrangement for wiring the embodiment illustrated in FIG; 6.

FIG. 10 schematically illustrates another' arrangement for wiring the embodimentillustrated in FIG. 6. FIG. 11 is a top plan view, with thesensor cover removed, of yet another sensor embodying features of the disclosure.

According to a further feature of .the invention, the

spring comprises an elongated member having a relatively-coiledconfiguration and is prestressed to move toward one of its configurations. The spring member is arranged to move toward its prestressed configuration to normally urge the disk to'the initial disk position, and is arranged to move away from its prestressed configuration to yieldablyallow movements of the disk toward any one of the disk actuation positions upon a change of velocity of the housing.

According to one of the disclosed embodiments, the disk is positioned in a narrow cavity having apair of angular sides defining therebetween the initial position and a curved contact defining the plurality of actuation positions. The disk is held against the angular sides .of the cavity by a compact, resilient device such as a F1612 is a sectional view taken on line 'l2l2of FIG. 11, and including the sensor cover.

FIG. 13 is a top pla'nview, with 'the'top portions removed, of still another sensorembodying featuresof the disclosure. 5 f v I J FIG. 14 is a fragmentary sectional view taken on line 14-14 of FIG..13, and. including the sensor top portions;

DETAILED DESCRIPTION OF THE DRAWINGS FIG." 1 schematically illustrates an electricalcircuit I 12 that is used in a passive restraint system of a known design for a vehicle, e .g., the system illustrated in US.

cal power source 16 illustrated as a battery and one lead 18 of a sensor 20. A second lead 22 of sensor is connected to power source 16. When sensor 20 isactuated by a collision condition, it acts as a switch completing a circuit between actuator 14 and power source 16. The completion of the circuit causes the passive restraint system to operate.

One embodiment of a sensor according to the present disclosure is illustrated in FIGS. 2 and 3 and is generally indicated at 24. Sensor 24 includes a generally cupshaped housing 26 having an electrically nonconductive plate 28 with a relatively flat sliding surface 30 and angularly related, relative to each other, guide or side walls 32 and 34. A suitable cover 36 is provided for housing 26 having an electrically nonconductive plate 38 with a relatively flat surface 40 parallel to surface 30. Walls 32 and 34 intersect at an angle of 90 which may be on opposite sides of the forward direction A in which the sensor 24 would normally be moving in a vehicle.

A cylindrical disk 42 is resiliently held at the intersection of walls 32 and 34 at an initial position by a band spring 44 such as a Negator spring. Spring 44 is a tightly wound metal band which when free winds upon itself into a coil about one or both ends. If spring 44 has a constant width throughout its length it will be a constant force device. It should be appreciated that a band spring is a very low mass device by design. Spring 44 is wound around disk 42 between upper and lower lips 46 and 48 at one end and is secured at its other end to a contact 50 mounted in housing 26. A lead 51 comparable to lead 18 in FIG. 1 is connected to contact 50 and extends outwardly from housing 26.

In instances where contact 50 is located away from wall 34 as illustrated in FIGS. 2 and 3, wall 32 may be made upof an upper and a lower section 52 and 54 (FIG. 3) having lower and upper surfaces 53 and 55, respectively, spaced a given amount to allow spring 44 to pass therebetween during movement of disk 42 and prevent vertical oscillation of the spring.

An arcuate, electrically conductive, resilient contact 56 is located between walls 32 and 34 distal from the walls intersection. Contact 56 includes a plurality of movably spaced fingers 58 which locate a plurality of actuation positions. The fingers 56 are connected to a conductive bar 57 which is connected to a lead 59, comparable to lead 22 in FIG. 1, which extends outwardly from housing 26.

During a head on collision, a vehicle, and accordingly a sensor 24 mounted thereon, will decelerate. The deceleration is not at a constant rate. As parts of the vehicle crush, the vehicle can and does accelerate a slight amount. The overall deceleration exerts a given g force on disk 42 causing the disk. to move from the initial position against the force of spring 44 away from the intersection of walls 32 and 34 toward one of the actuation positions at I contact 56. This movement causes disk 42 to rotate unwinding it from spring44 and thereby exposing a previously unexposed portion of the spring. If the deceleration lasts over a sufficiently long period of time, contact will be made between disk 42 and fingers 58 pushing the fingers toward wall 60 of cover 36. Preferably, contact is also made between the previously unexposed portion of spring 44 and the fingers 58. In such a way a more positive electrical contact can be assured since it is highly unlikely that the previously unexposed portion of spring 44 is contaminated by foreign matter. This contact between the disk and/or spring and the fingers will result in the closing, through contact lead 51, contact 50, disk 42 and/or spring 44, fingers 58, bar 57 andlead 59, of that portion of electrical circuit 12 in sensor 24 and the actuation of the passive restraint system.

During an angular collision the force exerted on disk 42 will have both forward and sideward components. As long as the collision occurs within the angle included between walls 32 and 34, the force resulting from the collision will cause a closing of the circuit through the sensor. By taking into consideration the various factors referred to in US. Pat. No. 3,556,556 a sensor 24 may be designed to complete the circuit or actuate above a given collision speed and at a given angular collision. If desired, the 90 included angle illustrated in FIGS. 2 and 3 may be increased or decreased;

It should be appreciated that the entire deceleration force acts through disk 42 and that portion of spring 44 wound around the disk. The portion of spring 44 between disk 42 and contact 50 has no material affect on the operation of the sensor ineither a head on" or an angular collision. This is a significant departure from the operation of previous sensors.

FIGS. 4 and 5 illustrate another embodiment of the disclosure in which a sensor 62 has two disks 64 and 66 located between upper and lower surfaces 68 and 70 partially defining a cavity 71 in a housing 72'. The disks are biased against a backing surface 74 in housing 72 by the band-type spring 75 previously described which is wound clockwise at one end around disk 64 between upper and lower lips (not illustrated) and counterclockwise at the other end around disk 66 between upper and lower lips 65 and 67 and secured at a center position to a post 76 located at the midpoint of backing surface 74. Post 76 comprises a screw 78 passing through upper and lower washers 80 separated by a bushing 82. A nut 84 is used to hold the screw. 78 rigid relative to housing 72. The included angle defined by backing surface 74 in cavity 71 is greater than 180.

A contact 88 is illustrated as a segment of a circular surface symmetrical about post 76 and contacting the outer ends of backing surface 74. Contact 88 includes an upper and a

lower member

90 and 92, respectively, each having a plurality of spaced fingers 94 and 96 projecting respectively below and above upper and lower surfaces 68 and 70. A cavity 98 is located behind fingers 94 and 96 to allow movement of them away from post 76. Referring again to FIG. 1 a lead 18 may be connected to upper member 90 and a lead 22 tolower member 92. 7 i

In operation, the g force created by deceleration existing in a collision acts against both disks 64 and 66. If the collision is head on both disks will move simultaneously outward into contact with the fingers 94 and 96 thereby completing the electrical circuit 12 through contact 18, fingers 94, disks 64 and 66, fingers 96 and contact 22 to actuate the passive restraint'system. The duration of the contact is maintained by the fact'that the fingers move rearwardly into cavity 98 as the disks 64 and 66 are forced further away from post 76 as a result ofthe deceleration forces. In an angular" collision of, for example, 45 degrees clockwise off dead center, as seen in FIG. 4, disk 66 will make contact with fingers 94 and 96 thereby completing the electrical circuit'l2 prior to contact between disk 64 and fingers 94 and 96. This early contact of disk 66 is a result of the fact that disk 66 has a shorter distance to travel than disk64. It should be appreciated, however, that the difference in time between contact of disk 64 and disk 66 with fingers 94 and 96 is minimal. The presences, therefore, of the two disks increases the redundancy of sensor 62.

It should again be noted that the mass of spring 75 has little if any effect on the operation of sensor 62 in either a head on or an angular collision. It should also be noted that contact 88 may be replaced by a contact 56 illustrated in FIGS. 2 and 3 and lead 18 connected to contact 56 and lead 22 connected to post 76.

FIGS. 6 to illustrate yet another embodiment of the disclosure in which a sensor 101 has two sets of disks 100 and 102, each similar to the set illustrated in FIGS. 4 and 5, located in a single housing 104. Set 100 comprises

disks

106 and 108 biased against a backing surface 110 by a band-type spring 112 in the manner previously described for FIGS. 4 and 5. Directly below set 100, set 102 comprises a mating set of disks 1 14 and 116, illustrated schematically in FIGS. 9 and 10, which are similar to

disks

106 and 108 and biased against a second backing surface 118 by another band-type spring 120 in the manner previously described.-A onepiece contact 122 comprising a plurality of upper and lower spaced fingers 123 and 124projecting inwardly toward the

disks

106, 108, 114 and 116 defines a segment of a circular surface terminating adjacent the outer ends of backing surfaces 110 and 118. The'included angle of operation, as illustrated, may be greater 9. 106 108 +114 116 From the above it can readily be seen that the redundancy of the system is greatly increased over those of prior systems. Inadvertent actuation is also reduced.

Sensor 101 may also be wired to leads l8 and 22 in another manner which is illustrated in FIG. 10. Lead'18 may be connected to contact 122 and lead 22 may be connected to

springs

112 and 120. The circuit across sensor 101 in such an arrangement will be completed upon engagement of any one of the disks 106,108, 114

, or 116 with contact 122. This method of wiring also than 180 degrees. A'cavity 126 is located rearwardly of contact 122 to allow movement of

fingers

123 and 124 away from

surfaces

110 and 118 upon contact with the disks to extend the time duration of contact therebetween.

In operation deceleration forces caused by a'collision will result in corresponding movement of disks 1'06 and 114 and

disks

108 and 116. In the event ofa head on collision all disks will engage contact 122 at the same instant. For an angular collision,

disks

106 and 114 will engage contact 122 at the same time and

disks

108 and 116 will engage contact 122 at an instant before or 7 after

disks

106 and 114 make engagement depending upon what side of center contact is made. The presence of cavity 126 and movement of the fingers into the cavity will result in the duration of the engagement being increased over that of a rigid contact.

The sensor 101 may be wired to leads 18 and 22 in several manners. FIGS. 7 and 9 illustrate one method in which lead 18'may be attached to spring112 of set 100 and the other lead 22 may be attached to spring 120 of set 102. The sets 100 and 102 may be insulated from one another by any one of a number of known ways. In the embodiment'illustrated in FIGS. 7 and 9, before the circuit through sensor 101 can be completed, a disk 106 or- 108 from set 100 and a

disk

114 or 116 from set 102 must be engagedwith contact 122 at the same time. The completion of the circuit through sensor 101 could therefore occur when engagement occurs between the disks and the contact in any one of the following combinations. The numbers correspond to the disks engaged with contact 122.

OUIJiUNtgreatly increases redundancy over prior systems. Other variations in wiring, for example, modifications of those previously described, may also be used.

FIGS. 11 and 12 illustrate another sensor 123 which embodies features of the disclosure which are similar to those illustrated in FIGS. 4 to 10. Two disks 124and 126 are located in a recess 128 in a housing 130. Recess 128 is defined by upper and

lower surfaces

132 and 134, side backing surfaces 136 and 138 interconnected by a rear backing surface 140 to define a pair of initial positions 142 conforming to the configuration of

disks

124 and 126 and a forward parabolic shaped contact 144. A smaller recess 146 communicates with recess 128.

Each disk, 124, 126, comprise an upper and a

lower portion

148 and 150 interconnected by a stud 152 upon which is engaged a bushing 154 that is adapted to be rotated. A spring 156 has a coiled portion 158 located in recess 146 and a pair of outer arms 160 and 162. Each arm 160, 162 hasa

circular end portion

164 and 166 respectively, engaged with a busing 154. The spring 156 is prestressed to retain

disks

124 and 126 within their respective initial positions 142 respectively against

walls

136 and 140 and 138 and 140.

Contact 144 includes separate upper and lower portions 157 and 159 each having a plurality of spaced fingers 161 similar to those'illustrated in FIGS. 4 and 5.

Upper portion 157 is connected to lead 18 while lower portion 159 is connected to lead 22 in FIG. 1. v

In operation, sensor 123 is mounted on a vehicle which is normally moved in the direction indicated by arrow A. Upon the occurrence of a head on collision both disks will be forced into engagement with contact 144 at the same time. During an angular collision, for example, 30 relative tothe direction of arrow A, one disk will move into engagement with contact 144 while the other disk will maintain its position as illustrated in dot-dash lines in FIG. 11. In either instance, either a head on or an angular collision, the

disks

124 and 126 and spring 156 move as a unit. As in' the embodiments previously described, this factor is significant since the force exerted by the collision does not impair the operation of the sensor. This is a major departure from multidirectional prior art sensing devices.- When either

disk

124 or 126 engages contact 144 the circuit defines an outer portion of recess 167 and terminates proximate the ends of

walls

168 and 170. Fingers 172 are connected to lead 18 and fingers 173 are connected to lead 22. Two

rotatable posts

174 and 176 are located on either side of the initial position of disk 169 and each includes a drum 178 adapted to be rotated on a needle roller 180 mounted in housing 165.

A band-type spring 182, i.e., a band prestressed to wind upon itself into a coil, is wound at its ends around each of the drums 178 several times. One of the ends is wound in a clockwise direction and the other end is wound in acounterclockwise direction. Spring 182, in-

termediate its ends, encircles a portion of disk 169 between upper and lower lips 179 and 181.

In operation, as forces are exerted against disk 169, the disk moves along the lower surface 184 into contact with

fingers

172 and 173 completing the circuit through sensor 163. Movement of disk 169 is restrained by the natural tendency of the ends of spring 182 to coil around drums 178. It will be noted that dur ing a head on collision both ends will unwind evenly. During angular collisions one end will unwind more than the other end. If the band is a constant width and thickness it will be a constant force device, i.e., the force will not depend upon the amount of uncoiling that occurs. In such a case the force exerted on disk 169 will be the same whether the forces are from a head on or an angular collision. Further, as in the case for the other embodiments of the disclosure, the forces exerted upon spring 182 or the other components of the sensor 163 do not affect its actuation.

In all of the above-referred to embodiments certain design factors should be considered. The material used to define the backing surfaces should be of a type which will absorb impacts by the disks without causing a significant rebound. Further, the surfaces on which the disks slide should be smooth and free from protrusions. The distance between the disks and the contact should be chosen so that the disks will not engage the contact inadvertently or during minor collisions or shocks such as created by an automobile hitting a pot hole" in a road. Also, vertical movement of a disk should be kept-to a minimum. This may be accomplished by having the distance between the upper and lower walls ten to twenty thousands of an inch greater than the maximum thickness of a disk. In determining this distance as well as the design of the disks and springs, it is necessary to consider not only the magnitude of the g force created by the change in velocity but also the duration of the g" force. It should be appreciated that a collision condition involving an automobile at which the sensor should actuate a passive restraint system might have a lower g" exerted when the automobile hits a hole in the road, however, the duration of the g force created by the collision will bemuch longer than the duration of the g force created by the hole in the road.

It should also be appreciated that the winding of the spring around the disks illustrated in FIGS. 4to 8 may be a significant factor. In the illustrated embodiments care must be taken not to permanently deform the spring proximate the center pole or contact. By winding the springs as illustrated in these figures the spring section connected to a first disk will prevent the second disk from becoming lodged between the first disk and the center pole or contact. It may further be desirable when using two disks in a single cavity to construct the force than that cavity in a manner to provide a separate V-shaped support for each disk. In viewing FIG. 2 it will be readily apparent that the two V-shaped supports would have side walls 32 and 34.for each of the two disks 42 located on a single flat sliding surface 30. A single contact 56 could be used in such an arrangement.

It is further contemplated thata single vane in the form of a thin plate pivotally connected to a center post could be located between two disks to keep them from interferring with one another. For example, in the embodiment illustrated in FIGS. 4 and S-the thin plate would be pivotally connected to post 76 between disks 64and 66 and would extend to a position proximate I contact 88. The plate could have an edgein sliding engagement with surface and be slightly narrowerthan the distance between surfaces 68 and 70. p

In each embodiment the spring-disk(s) relationship is such that the spring moves in the same general direction as the disk(s) from the initial position to one of the actuation positions. The force exerted on the mass of the spring by the collision, therefore, does not act in a manner which is opposed to theforce exerted on the mass of .the disk. The effect of the disclosed springdisk(s) relationship is that the movement of the mass of the spring is additive to the movement of the mass of the disk(s). This additive movement eliminates secondary forces on the movable components which would tend to cause the components to move in a manner to resist actuation.

It should further be appreciated thatthespring in each, of the disclosed embodiments comprises an elongated member having a relatively straight configuration and a relatively coiled configuration. The spring is prestressed to move from one configuration to the other configuration to normally urge a vdisk(s) to the initial position. The presence of a force created by a collig sion moves the disk(s) from the initial position .to one of the actuation positions and forces the spring to move against the prestressed force from one configuration to the other configuration. I

What is claimed is: 1. An apparatus to sense a change in velocity of a moving body, said apparatus comprising: a. means defining an initial position on said body; b. means defining a plurality of actuation positions on said body spaced from said initial position and located in a plurality of directions from said initial position; t c. a member movable between said initial position and said actuation positions in response to changes in velocity of said body; I d. a yieldable resilient band holding said movable member and prestressed to wind upon itself into a tightly wound coil; and e. means mounting said band l. to normally urge said movable member to and yieldably hold said movable member in said initial position in response to self-winding of said band upon itself, and 2. to allow said band to unwind in response to movement of said movable member to one of said actuation positions during a change in velocity of said body, whereby the unwinding band yieldably resists the movement of the movable member. 2. An apparatus according to claim 1 wherein:

ing:

f. said body includes two connected walls located 'at an angle with respect to one another and having outer ends;

g. said initial position is located at the connection of a portion of said band is located intermediate said upper and lower portions. r

4. An apparatus according to claim 2 wherein;

k. said band is electrically conductive;

1. an electrically conductive contact is located at said actuation positions;

in. said band and said contact are adapted to be connected in series to an electrical circuit;

in. a portion of said band is wound around said movable member; and

0. said band engages said contact when said movable member is in one of said actuation positions whereby a path for electrical particles is created when said movable member is in one of said actuation positions through said apparatus between said band and said contact.

5. An apparatus according to claim 4 wherein:

p. said contact includes a plurality of resilient fingers adapted to be moved from a first position to a stressed position.

6. An apparatus according to claim 2 wherein:

i. a contact is located at said actuation positions and includes an upper contact having a plurality of re silient upper fingers and a lower contact having a plurality of resilient lower fingers, said upper and lower contacts being spaced from one another and being electrically conductive and adapted to be connected in series to an electrical circuit, said fingers being movable from an initial position to a position in which they are stressed; and

v j. said movable member is electrically conductive whereby a path for electrical particles is created when said movable member is in one of said actuation position through said apparatus between said upper contact, said movable member and said lower contact.

7. An apparatus according to claim 1 wherein:

f. said mounting means includes first and second drums mounted for rotational movement on said body;

g. said band has a first end wound around said first drum;

h. said bandhas a second end wound around said second drum; and

i.'said band engages said disk intermediate said'first and second ends. 1

8. An apparatus according to claim 1 further includf. electrical means to define an open electrical circuit across said apparatus when said movable member is positioned at said initial position and a closed electrical circuit across said apparatus when said movable member is positioned at one of said actuation positions.

9. An apparatus" according to claim l'further includf. a second member movable between said initial position and said actuation positions in response to changes in velocity of said body; and

' g. wherein said means further mounts said band to normally urge said second movable member and yieldably hold said second movable member in said initial position and allow said band to unwindin response to movement of said second movable member to one of said actuation positions during change in velocity of said body.

10. An apparatus according to claim 9 wherein:

h. said resilient band has first and second ends, said first end iswound around said first movable member in oneclockwise direction and said second end is wound around said second movable member in the other clockwise direction.

1 1. An apparatus according to claim 9 further including:

h.1 means defining asecond plurality of actuation positions on said body spaced from and located adjacent to said first plurality of actuation positions;

i. means defining a second initial position on said body spaced from and located adjacent to said first initial position; i 3 1 j. a third member movable between said second initial position and said second actuation positions in response to changes in velocity of said body;

k. a fourth member movable between said second initial position and said second actuation positions in response to changes in velocity of said body;

l. a yieldably resilient band holding said third and fourth movable members and prestressed to wind upon itself into a coil; and v m. means mounting said second band 1. to normally urge said third and fourth movable members to and yieldably hold said third and fourth movable members in said second initial position in response to self-winding of the second band upon itself, and 2. to allow said band to unwind in response to movement of said third and fourth movable members to said second actuation positions duringa change in velocity of said body. I

12. An apparatus according to claim 11 wherein:

n. said first plurality of actuation positions include a first electrically conductive contact;

0. said second plurality of actuation positions include a second electrically conductive contact connected to said first contact by a conductor; a

p. said first and second movable members and said first resilient band are electrically conductive;

q. said third and fourth movable members and said second resilient band are electrically conductive; r. a first electrical lead is attached to said first resilient band; and

a second electrical lead is attached to said second resilient band whereby movement of either said first or second movable members into engagement with said first contact together with movement of either said third or fourth movable members into engagement with said second contact will define a path for electrical particles to flow between said first lead and said second lead. 13. An apparatus according to claim 11 wherein: n. said first plurality of actuation positions include a first electrically conductive contact;

0. said second plurality of actuation positions include a second electrically conductive contact connected to said first contact by a conductor;

p. said movable members and said first and second resilient bands are electrically conductive;

. a first electrical lead is attached to said first and second resilient bands; and

a second electrical lead is attached to said contacts whereby movement of any movable member into engagement with a respective contact will define a path through which electrical particles can flow between said first and second leads.

14. An apparatus according to claim 1 wherein said resilient band has a substantially constant resisting force.

15. An apparatus for sensing a change of velocity comprising:

a. a housing;

b. a first wall in said housing having a first backing surface and an outer end;

c. a second wall in said housing having a second a plurality of actuation positions located proximate backing surface and an outer end, said first and second backing surfaces together partially defining a cavity in said housing;

and between said outer ends of said first and second walls;

. a first disk located in said cavity and contacting g. resilient means connected to said disks to urge each of said disks toward their respective surfaces and yieldably resist movement of said disks toward said actuation positions.

16. An apparatus according to claim 15 wherein: h. a vane is pivotally connected to said housing intermediate said first and second walls, said vane extending from said point of pivotal connection to a location adjacent said contact intermediate said first and second disks.

17. An apparatus according to claim 1 5 wherein: h. said resilient means is a band having first and second ends, said band being prestressed to wind upon itself to form a coil, said first end is wound around said first disk and said second end is wound around said second disk and said band is attached intermediate said first and second ends to said housing at a location intermediate said first and second backing surfaces.

18. An apparatus according to claim 15 wherein: h. said disks are electrically conductive;

19. An apparatus according to claim 18 wherein: h.

. an electrically conductive contact is located at said actuation positions; and

. the engagement of one of said disks with said contact creates a path for electrical particles to flow through said apparatus between said disk and said contact.

. said contact includes a plurality of resilient, spaced fingers, said fingers being adapted to move when engagement is made by them with one of said disks to absorb the momentum of said contacting disk and yieldably resist further movement of said disk in the disks projected path of travel.

20. An apparatus according to claim 15 wherein:

h. said housing has an upper surface and a lower surface, said upper and lower surfaces being parallel and spaced to define a portion of said cavity;

i. said disks are adapted to slide on said lower surface; and

j. the distance between said upper and lower surfaces is slightly greater than the dimension of the corresponding portions of said disks to restrain said disks from moving normal to said upper and lower surfaces.

21. An apparatus according to claim 15 wherein:

h. said resilient means comprises a coil spring having first and second arms, said first arm being connected to said first disk and said second arm being connected to said second disk.

22. An apparatus according to claim 15 wherein said resilient means yieldably resists movement of said disks with a substantially constant biasing force.

23. An apparatus to sense a change of velocity comprising:

a. a housing having a cavity;

b. means defining an initial position in said cavity;

c. means defining a plurality of actuation positions in said cavity spaced from said initial position and located in a plurality of directions from said initial position;

d. a member of a given mass in said cavity; said member being adapted to move from said initial position to one of said actuation positions upon a change in velocity of said housing; and I e. resilient means connected to said movable member and normally operative to urge said movable member to said initial position, said resilient means being arranged so that, in response to movement of said movable member toward any of said actuation positions, the resultant movement of the mass of said resilient means is in the same general direction as the movement of the movable member so that the effect of the mass movement of said resilient means is always additive with respect to the effect of the movement of the movable member.

24. An apparatus according to claim 23 wherein said resilient means yieldably resists movement of said movable member from said initial position to any'of said actuation positions with a substantially constant force.

25. An apparatus to sense a change of velocity comprising:

straight configuration and a relatively coiled configuration and being prestressed to move toward one of said configurations, said spring member engaging said movable member and being'operative position and 2. to move away from said one configuration toward its other configuration to yieldably allow movement of said movable member toward any velocity of said housing. j v I a v 26. An apparatus according to claim 2Swherein Said elongated spring member exerts a substantially constant biasing force in moving from one of its configurations to the other configuration.

27; An apparatus to sensea change in velocity of a moving body, said apparatus comprising:

A. means defining an initial position on said body; B. means defining an actuation position on said body spaced from said initial position; 'C. a member movable between saidinitial position and said actuation position in-response to a change oneof saidactuation positions uponja change in n I in velocity of said body; I

D. a yieldable resilient hand holding said movable member and prestressed to wind upon itself intoa tightly wound coil; and E. means mounting said band l l. to normally urge saidmovable member to and I tially constant biasing force on said movable member.

yieldably hold said movable member in said ini .tial position in response to self-winding ofjsaidf

Claims

1. An apparatus to sense a change in velocity of a moving body, said apparatus comprising: a. means defining an initial position on said body; b. means defining a plurality of actuation positions on said body spaced from said initial position and located in a plurality of directions from said initial position; c. a member movable between said initial position and said actuation positions in response to changes in velocity of said body; d. a yieldable resilient band holding said movable member and prestressed to wind upon itself into a tightly wound coil; and e. means mounting said band 1. to normally urge said movable member to and yieldably hold said movable member in said initial position in response to self-winding of said band upon itself, and 2. to allow said band to unwind in response to movement of said movable member to one of said actuation positions during a change in velocity of said body, whereby the unwinding band yieldably resists the movement of the movable member.

2. An apparatus according to claim 1 wherein: f. said body includes two connected walls located at an angle with respect to one another and having outer ends; g. said initial position is located at the connection of said walls; and h. said plurality of actuation positions are spaced along an arcuate line that terminates adjacent said outer ends of said walls.

2. to allow said band to unwind in response to movement of said movable member to said actuation position during a change in velocity of said body, whereby the unwinding band yieldably resists the movement of the movable member from said initial position to said actuation position.

2. to allow said band to unwind in response to movement of said movable member to one of said actuation positions during a change in velocity of said body, whereby the unwinding band yieldably resists the movement of the movable member.

2. to move away from said one configuration toward its other configuration to yieldably allow movement of said movable member toward any one of said actuation positions upon a change in velocity of said housing.

2. to allow said band to unwind in response to movement of said third and fourth movable members to said second actuation positions during a change in velocity of said body.

3. An apparatus according to claim 2 wherein: i. one of said connected walls is bifurcated and has an upper and a lower portion; and a portion of said band is located intermediate said upper and lower portions.

4. An apparatus according to claim 2 wherein: k. said band is electrically conductive; l. an electrically conductive contact is located at said actuation positions; m. said band and said contact are adapted to be connected in series to an electrical circuit; n. a portion of said band is wound around said movable member; and o. said band engages said contact when said movable member is in one of said actuation positions whereby a path for electrical particles is created when said movable member is in one of said actuation positions through said apparatus between said band and said contact.

5. An apparatus according to claim 4 wherein: p. said contact includes a plurality of resilient fingers adapted to be moved from a first position to a stressed position.

6. An apparatus according to claim 2 wherein: i. a contact is located at said actuation positions and includes an upper contact having a plurality of resilient upper fingers and a lower contact having a plurality of resilient lower fingers, said upper and lower contacts being spaced from one another and being electrically conductive and adapted to be connected in series to an electrical circuit, said fingers being movable from an initial position to a position in which they are stressed; and j. said movable member is electrically conductive whereby a path for electrical particles is created when said movable member is in one of said actuation position through said apparatus between said upper contact, said movable member and said lower contAct.

7. An apparatus according to claim 1 wherein: f. said mounting means includes first and second drums mounted for rotational movement on said body; g. said band has a first end wound around said first drum; h. said band has a second end wound around said second drum; and i. said band engages said disk intermediate said first and second ends.

8. An apparatus according to claim 1 further including: f. electrical means to define an open electrical circuit across said apparatus when said movable member is positioned at said initial position and a closed electrical circuit across said apparatus when said movable member is positioned at one of said actuation positions.

9. An apparatus according to claim 1 further including: f. a second member movable between said initial position and said actuation positions in response to changes in velocity of said body; and g. wherein said means further mounts said band to normally urge said second movable member and yieldably hold said second movable member in said initial position and allow said band to unwind in response to movement of said second movable member to one of said actuation positions during a change in velocity of said body.

10. An apparatus according to claim 9 wherein: h. said resilient band has first and second ends, said first end is wound around said first movable member in one clockwise direction and said second end is wound around said second movable member in the other clockwise direction.

11. An apparatus according to claim 9 further including: h. means defining a second plurality of actuation positions on said body spaced from and located adjacent to said first plurality of actuation positions; i. means defining a second initial position on said body spaced from and located adjacent to said first initial position; j. a third member movable between said second initial position and said second actuation positions in response to changes in velocity of said body; k. a fourth member movable between said second initial position and said second actuation positions in response to changes in velocity of said body; l. a yieldably resilient band holding said third and fourth movable members and prestressed to wind upon itself into a coil; and m. means mounting said second band

12. An apparatus according to claim 11 wherein: n. said first plurality of actuation positions include a first electrically conductive contact; o. said second plurality of actuation positions include a second electrically conductive contact connected to said first contact by a conductor; p. said first and second movable members and said first resilient band are electrically conductive; q. said third and fourth movable members and said second resilient band are electrically conductive; r. a first electrical lead is attached to said first resilient band; and s. a second electrical lead is attached to said second resilient band whereby movement of either said first or second movable members into engagement with said first contact together with movement of either said third or fourth movable members into engagement with said second contact will define a path for electrical particles to flow between said first lead and said second lead.

13. An apparatus according to claim 11 wherein: n. said first plurality of actuation positions include a first electrically conductive contact; o. said second plurality of actuation positions include a second electrically conductive contact connected to said first contact by a conductOr; p. said movable members and said first and second resilient bands are electrically conductive; q. a first electrical lead is attached to said first and second resilient bands; and r. a second electrical lead is attached to said contacts whereby movement of any movable member into engagement with a respective contact will define a path through which electrical particles can flow between said first and second leads.

15. An apparatus for sensing a change of velocity comprising: a. a housing; b. a first wall in said housing having a first backing surface and an outer end; c. a second wall in said housing having a second backing surface and an outer end, said first and second backing surfaces together partially defining a cavity in said housing; d. a plurality of actuation positions located proximate and between said outer ends of said first and second walls; e. a first disk located in said cavity and contacting said first surface, said first disk being movable from said first surface to one of said actuation positions in response to a change in velocity of said housing; f. a second disk located in said cavity and contacting said second surface, said second disk being movable from said second surface to one of said actuation positions in response to a change in velocity of said housing; and g. resilient means connected to said disks to urge each of said disks toward their respective surfaces and yieldably resist movement of said disks toward said actuation positions.

17. An apparatus according to claim 15 wherein: h. said resilient means is a band having first and second ends, said band being prestressed to wind upon itself to form a coil, said first end is wound around said first disk and said second end is wound around said second disk and said band is attached intermediate said first and second ends to said housing at a location intermediate said first and second backing surfaces.

18. An apparatus according to claim 15 wherein: h. said disks are electrically conductive; i. an electrically conductive contact is located at said actuation positions; and j. the engagement of one of said disks with said contact creates a path for electrical particles to flow through said apparatus between said disk and said contact.

19. An apparatus according to claim 18 wherein: h. said contact includes a plurality of resilient, spaced fingers, said fingers being adapted to move when engagement is made by them with one of said disks to absorb the momentum of said contacting disk and yieldably resist further movement of said disk in the disk''s projected path of travel.

20. An apparatus according to claim 15 wherein: h. said housing has an upper surface and a lower surface, said upper and lower surfaces being parallel and spaced to define a portion of said cavity; i. said disks are adapted to slide on said lower surface; and j. the distance between said upper and lower surfaces is slightly greater than the dimension of the corresponding portions of said disks to restrain said disks from moving normal to said upper and lower surfaces.

21. An apparatus according to claim 15 wherein: h. said resilient means comprises a coil spring having first and second arms, said first arm being connected to said first disk and said second arm being connected to said second disk.

23. An apparatus to sense a change of velocity comprising: a. a hOusing having a cavity; b. means defining an initial position in said cavity; c. means defining a plurality of actuation positions in said cavity spaced from said initial position and located in a plurality of directions from said initial position; d. a member of a given mass in said cavity; said member being adapted to move from said initial position to one of said actuation positions upon a change in velocity of said housing; and e. resilient means connected to said movable member and normally operative to urge said movable member to said initial position, said resilient means being arranged so that, in response to movement of said movable member toward any of said actuation positions, the resultant movement of the mass of said resilient means is in the same general direction as the movement of the movable member so that the effect of the mass movement of said resilient means is always additive with respect to the effect of the movement of the movable member.

24. An apparatus according to claim 23 wherein said resilient means yieldably resists movement of said movable member from said initial position to any of said actuation positions with a substantially constant force.

25. An apparatus to sense a change of velocity comprising: a. a housing having a cavity; b. means defining an initial position in said cavity; c. means defining a plurality of actuation positions in said cavity spaced from said initial position and located in a plurality of directions from said initial position; d. a member in said cavity adapted to move from said initial position to one of said actuation positions upon a change in velocity of said housing; and e. an elongated spring member having a relatively straight configuration and a relatively coiled configuration and being prestressed to move toward one of said configurations, said spring member engaging said movable member and being operative

26. An apparatus according to claim 25 wherein said elongated spring member exerts a substantially constant biasing force in moving from one of its configurations to the other configuration.

27. An apparatus to sense a change in velocity of a moving body, said apparatus comprising: A. means defining an initial position on said body; B. means defining an actuation position on said body spaced from said initial position; C. a member movable between said initial position and said actuation position in response to a change in velocity of said body; D. a yieldable resilient band holding said movable member and prestressed to wind upon itself into a tightly wound coil; and E. means mounting said band

28. The apparatus of claim 27 wherein said band is of constant width and thickness to provide a substantially constant biasing force on said movable member.