CA1108721A - Velocity change sensor - Google Patents
Velocity change sensorInfo
- Publication number
- CA1108721A CA1108721A CA353,957A CA353957A CA1108721A CA 1108721 A CA1108721 A CA 1108721A CA 353957 A CA353957 A CA 353957A CA 1108721 A CA1108721 A CA 1108721A
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- sensing mass
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Abstract
VELOCITY CHANGE SENSOR
ABSTRACT OF THE DISCLOSURE
A velocity change sensor adapted for mounting on a vehicle equipped with a passenger protective device, such as an inflatable air bag, comprises a body fitted with a normally open electrical switch connected to the passenger protective device's operating mechanism and adapted to be closed by a sensing mass upon movement of such sensing mass a predetermined distance in response to acceleration of the vehicle above a predetermined threshold. The sensing mass is biased to a normally inactive, initial position under a force which establishes the acceleration threshold. A
biasing mass engages the sensing mass when the latter is in its initial position but moves out of engagement with the sensing mass in response to acceleration of the vehicle above the threshold level to permit movement of the sensing mass from its initial position toward its passenger protective device operating position. Movement of the biasing mass is damped to prevent rebounding of the biasing mass and con-sequent interference with movement of the sensing mass.
Movement of the sensing mass also is damped to prevent operation of the passenger protective device except in those instances in which the acceleration and duration thereof are of such magnitude as to require operation of the pro-tective device.
ABSTRACT OF THE DISCLOSURE
A velocity change sensor adapted for mounting on a vehicle equipped with a passenger protective device, such as an inflatable air bag, comprises a body fitted with a normally open electrical switch connected to the passenger protective device's operating mechanism and adapted to be closed by a sensing mass upon movement of such sensing mass a predetermined distance in response to acceleration of the vehicle above a predetermined threshold. The sensing mass is biased to a normally inactive, initial position under a force which establishes the acceleration threshold. A
biasing mass engages the sensing mass when the latter is in its initial position but moves out of engagement with the sensing mass in response to acceleration of the vehicle above the threshold level to permit movement of the sensing mass from its initial position toward its passenger protective device operating position. Movement of the biasing mass is damped to prevent rebounding of the biasing mass and con-sequent interference with movement of the sensing mass.
Movement of the sensing mass also is damped to prevent operation of the passenger protective device except in those instances in which the acceleration and duration thereof are of such magnitude as to require operation of the pro-tective device.
Description
J~ t;i~
1 ~ne of -the devices intended to protect a vehicle's
1 ~ne of -the devices intended to protect a vehicle's
2¦ occupant against injury is an instrumentality such as an in-
3 ¦flatable airbag which is house~ in the passenger compartment
4 forwardly of the occupan-t in a deflated condition. When such
5 ¦vehicle is subjected to acceleration of the kind accompanying 61 a crash, the airbag inflates to provide a protective cushion 7 ¦for the occupant.
When a moving vehicle becomes involved in a crash 10 ¦ of such severity as to slow or stop the vehicle suddenly, an 11 occupant of the vehicle will continue forward movement at the 12 rate the vehicle was traveling at the time of the crash until 13 such time as the occupant collides with some portion of the 14 structure of the passenger compartment. If serious injury to the occupant is to be prevented, the airbag must be fully 16 inflated before a collision occurs between the occupant and 17 some structure of the passenger compartment. It has been 18 found that, typically, the driver of a vehicle can move 19 forwardly only about five inches from the driving position before a restraining device such as an airbag is needed to 21 prevent injury. All airbag inflating mechanisms require a 22 period of time, such as thirty milliseconds, to effect in-23 flation of the airbag once a signal initiating inflation has 24 been received from a sensor. Under these circumstances, an airbag pxotective device, to be effective, must become in-~6 flated thirty milliseconds before the occupant has moved 27 five inches from the position he occupied at the time of 28 the crash.
2~
~0 It has been determined that a passenger protective Y ~
l ¦device is needed when the movement of the vehicle occupant 2 ¦relative to the vehicle is at a velocity of about twelve 3 miles per hour. Thus, an ideal sensor is one which will 4 determine that the occupan-t will collide with some portion 51 of the vehicle's interior at a speed of twelve miles per
When a moving vehicle becomes involved in a crash 10 ¦ of such severity as to slow or stop the vehicle suddenly, an 11 occupant of the vehicle will continue forward movement at the 12 rate the vehicle was traveling at the time of the crash until 13 such time as the occupant collides with some portion of the 14 structure of the passenger compartment. If serious injury to the occupant is to be prevented, the airbag must be fully 16 inflated before a collision occurs between the occupant and 17 some structure of the passenger compartment. It has been 18 found that, typically, the driver of a vehicle can move 19 forwardly only about five inches from the driving position before a restraining device such as an airbag is needed to 21 prevent injury. All airbag inflating mechanisms require a 22 period of time, such as thirty milliseconds, to effect in-23 flation of the airbag once a signal initiating inflation has 24 been received from a sensor. Under these circumstances, an airbag pxotective device, to be effective, must become in-~6 flated thirty milliseconds before the occupant has moved 27 five inches from the position he occupied at the time of 28 the crash.
2~
~0 It has been determined that a passenger protective Y ~
l ¦device is needed when the movement of the vehicle occupant 2 ¦relative to the vehicle is at a velocity of about twelve 3 miles per hour. Thus, an ideal sensor is one which will 4 determine that the occupan-t will collide with some portion 51 of the vehicle's interior at a speed of twelve miles per
6 hour or greater, and thirty milliseconds before the occupant
7 has moved forwardly five inches.
9 ¦ Since an airbag protective device is one which is designed to prevent forcible collision between a vehicle oc-11 cupant and some portion of the passenger compartment, it is 12¦ important that the sensor which initiates operation of the air-13¦ bag inflation mechanism be one which is responsive to the ac-14¦ celeration of the passenger compartment, rather than some other part of the vehicle. Not all crashes, however, result 16¦ in acceleration of the vehicle's passenger compartment to a 17 ¦ degree necessary to require operation of the airbag. For ex-18 ample, if a front fender or bumper of a vehicle should collide 19¦ with a pole or the like which breaks upon or shortly after 20¦ impact, a sensor mounted on the front fender or bumper could 21¦ experience a velocity change of twelve miles per hour, or 22¦ greater, before the pole breaks, whereas the passenger com-23 partment of the vehicle might experience a negligible velocity 24 change. Under these circumstances, inflation of the airbag 25 ¦would not be required and, if it were, it might even contribute 261 to a subsequent accident. It is important, therefore, that 27 the sensor or sensors with which a vehicle is equipped be lo-28 ¦cated in such positions and be of such construction as to be 2~ Ipredictive that the passenger compartment will undergo a ~0 ¦velocity change necessitating passenger protection.
F'rontal portions of the vehicle, i.e., bumpers, 2 fenders, radiators, and the like, may undergo a substantial 3 ¦velocity change relative to the passenger compartment inasmuch 4 las such frontal portions of a vehicle are capable of 5 ¦collapsing and absorbing energy. ThuS, sensors mounted at ~ ¦frontal positions on a vehicle should have characteristics 7 ¦different from sensors mounted on its firewall, for example,
9 ¦ Since an airbag protective device is one which is designed to prevent forcible collision between a vehicle oc-11 cupant and some portion of the passenger compartment, it is 12¦ important that the sensor which initiates operation of the air-13¦ bag inflation mechanism be one which is responsive to the ac-14¦ celeration of the passenger compartment, rather than some other part of the vehicle. Not all crashes, however, result 16¦ in acceleration of the vehicle's passenger compartment to a 17 ¦ degree necessary to require operation of the airbag. For ex-18 ample, if a front fender or bumper of a vehicle should collide 19¦ with a pole or the like which breaks upon or shortly after 20¦ impact, a sensor mounted on the front fender or bumper could 21¦ experience a velocity change of twelve miles per hour, or 22¦ greater, before the pole breaks, whereas the passenger com-23 partment of the vehicle might experience a negligible velocity 24 change. Under these circumstances, inflation of the airbag 25 ¦would not be required and, if it were, it might even contribute 261 to a subsequent accident. It is important, therefore, that 27 the sensor or sensors with which a vehicle is equipped be lo-28 ¦cated in such positions and be of such construction as to be 2~ Ipredictive that the passenger compartment will undergo a ~0 ¦velocity change necessitating passenger protection.
F'rontal portions of the vehicle, i.e., bumpers, 2 fenders, radiators, and the like, may undergo a substantial 3 ¦velocity change relative to the passenger compartment inasmuch 4 las such frontal portions of a vehicle are capable of 5 ¦collapsing and absorbing energy. ThuS, sensors mounted at ~ ¦frontal positions on a vehicle should have characteristics 7 ¦different from sensors mounted on its firewall, for example,
8 lin order to assure inflation of an airbag when required, but
9 ¦to avoid inflation cf the airbag in those instances in which it is not necessary.
12 In those sensors which initiate inflation of an 13 airbag via an electrical circuit which requires the closing 14~ for a finite period of time a normally open switch, care must be taken to ensure that the switch will remain closed, not 16 only for the minimum time required to effect circuit completion, 17¦ but also for a somewhat longer period of time so as to provide 18¦ a factor of safety. In sensors which utilize a biasing mass 19¦ to establish an acceleration threshold which must be exceeded 20 ¦ before closing of the switch is possible, there is a likelihood 21¦ that the biasing mass may move to a position in which the 22¦ switch operating means is free to move toward switch closing 23 position, but then rebound into the path of movemen-t of the 241 switch closing means and delay or prevent closing of the switch, 251 or effect premature reopening of the switch. On the other 26¦ hand, in some instances it may be desirable to delay closing 27 ¦ of the switch for a predetermined period of time so as to 28¦ avoid initiating operation of the airbag until sufficient time 2~ has lapsed to ensure that the circumstances necessitate airbag 3~¦ inflation.
.'Y~1~2~
1 Sensors construc-ted accordlng to -the invention are 2¦ so designed as to enable them to be mounted in selected posi-31 tions on a vehicle and sense velocity changes which require 4 and do not require actuation of a passenger protective device.
51 A sensor constructed in accordance with the ¦ 6 invention embodies many of the principles disclosed in United States Patent No. 3,97~,350, granted August 10, 1976, and 8 comprises a body adapted to be mounted on a vehicle or the like in a position to sense and respond to acceleration pulses.
Within a tubular passage in the body is mounted an acceleration 11 sensing mass formed of electrically conduc-tive material. The 12 sensing mass is movable in response to an acceleration pulse 13 from an initial position along a path leading to a normally 14¦ open switch that is connected via suitable wiring to the 15¦ operating mechanism of an inflatable airbag.
16¦ Biasing means acts on the sensing mass to bias 17¦ the latter to its initial position under a preselected force 18 which must be exceeded before the sensing mass may move from 19¦ its initial position. The biasing means includes a mass 20¦ which normally engages and maintains the sensing mass in its 21¦ initial position, but which moves out of engagement with the 22 sensing mass in response to acceleration greater than the 23 preselected biasing force, thereby freeing the latter for 241 movement toward the switch. Movement of the sensing mass is 251 fluid damped, either inertially or viscously. As thus far 26¦ described, the apparatus disclosed herein is quite similar 27 ¦ in function to that disclosed in the aforementioned patent.
28¦ Movement of the biasing mass in response to 20¦ acceleration is along a linear path, but cooperable means ~0 carried by the body and the biasing mass damp movement of _ 4 _ - , 1¦ the la-tter by transla-ting linear movement inko rotary movement 21 and dissipating some of the kinetic energy of the biasing mass.
3 Dissipation of kinetic energy prevents rehounding of the latter 4 into premature reengagement with the sensing mass. The means 51 for translating linear movemen-t of the biasing mass in-to 81 rotary movement may also function to delay movement of the 7 sensing mass into engagement with the switch.
9 Figure 1 is an enlarged, elevational view of a casing or housing within which a sensor constructed in 11 accordance with the invention is contained;
12¦ Figure 2 is a horizontal sectional view of a 13 sensor constructed in accordance with one embodiment of 14 the invention;
Figure 3 is a side elevational view, partly 16¦ broken away, of the sensor shown in Figure 2;
17¦ Figure 4 is a sectional view taken on the line 18¦ 4-4 of Figure 3;
19¦ Figure 5 is an elevational view of a detail as 20 ¦ viewed in the direction of the arrows 5-5 of Figure 4; and 21¦ Figure 6 is a view similar to Figure 2, but 22¦ illustrating a modified form of the invention.
24¦ A sensor constructed in accordance with the 251 invention is adapted to be enclosed within a sturdy casing or 26¦ housing 1 having flanges 2 provided with openings for the 27 ¦accommodation of screws or the like (not shown) to mount 28¦ the housing at a suitable lo-ation on and relative to the 2~ ¦longitudinal axis of a vehicle. A bushing 3 fits within 3~ ¦ and closes an opening formed in the housing 1 and accommodates ~ 72~
1¦ an insulated cable ~ containing electrical wiring -to be 21 described hereinafter. The housing 1 has a cavity therein 3 for the accommodation of a sensor.
51 A sensor constructed according to the embodiment shown in Figures 2~5 comprises a cylindrical body 5 formed of 7 electrically insulating material. The body 5 has a bore 6 81 closed at one end by a wall 7 provided with a pair of 9 diametrically opposed openings 8 therein which communicate
12 In those sensors which initiate inflation of an 13 airbag via an electrical circuit which requires the closing 14~ for a finite period of time a normally open switch, care must be taken to ensure that the switch will remain closed, not 16 only for the minimum time required to effect circuit completion, 17¦ but also for a somewhat longer period of time so as to provide 18¦ a factor of safety. In sensors which utilize a biasing mass 19¦ to establish an acceleration threshold which must be exceeded 20 ¦ before closing of the switch is possible, there is a likelihood 21¦ that the biasing mass may move to a position in which the 22¦ switch operating means is free to move toward switch closing 23 position, but then rebound into the path of movemen-t of the 241 switch closing means and delay or prevent closing of the switch, 251 or effect premature reopening of the switch. On the other 26¦ hand, in some instances it may be desirable to delay closing 27 ¦ of the switch for a predetermined period of time so as to 28¦ avoid initiating operation of the airbag until sufficient time 2~ has lapsed to ensure that the circumstances necessitate airbag 3~¦ inflation.
.'Y~1~2~
1 Sensors construc-ted accordlng to -the invention are 2¦ so designed as to enable them to be mounted in selected posi-31 tions on a vehicle and sense velocity changes which require 4 and do not require actuation of a passenger protective device.
51 A sensor constructed in accordance with the ¦ 6 invention embodies many of the principles disclosed in United States Patent No. 3,97~,350, granted August 10, 1976, and 8 comprises a body adapted to be mounted on a vehicle or the like in a position to sense and respond to acceleration pulses.
Within a tubular passage in the body is mounted an acceleration 11 sensing mass formed of electrically conduc-tive material. The 12 sensing mass is movable in response to an acceleration pulse 13 from an initial position along a path leading to a normally 14¦ open switch that is connected via suitable wiring to the 15¦ operating mechanism of an inflatable airbag.
16¦ Biasing means acts on the sensing mass to bias 17¦ the latter to its initial position under a preselected force 18 which must be exceeded before the sensing mass may move from 19¦ its initial position. The biasing means includes a mass 20¦ which normally engages and maintains the sensing mass in its 21¦ initial position, but which moves out of engagement with the 22 sensing mass in response to acceleration greater than the 23 preselected biasing force, thereby freeing the latter for 241 movement toward the switch. Movement of the sensing mass is 251 fluid damped, either inertially or viscously. As thus far 26¦ described, the apparatus disclosed herein is quite similar 27 ¦ in function to that disclosed in the aforementioned patent.
28¦ Movement of the biasing mass in response to 20¦ acceleration is along a linear path, but cooperable means ~0 carried by the body and the biasing mass damp movement of _ 4 _ - , 1¦ the la-tter by transla-ting linear movement inko rotary movement 21 and dissipating some of the kinetic energy of the biasing mass.
3 Dissipation of kinetic energy prevents rehounding of the latter 4 into premature reengagement with the sensing mass. The means 51 for translating linear movemen-t of the biasing mass in-to 81 rotary movement may also function to delay movement of the 7 sensing mass into engagement with the switch.
9 Figure 1 is an enlarged, elevational view of a casing or housing within which a sensor constructed in 11 accordance with the invention is contained;
12¦ Figure 2 is a horizontal sectional view of a 13 sensor constructed in accordance with one embodiment of 14 the invention;
Figure 3 is a side elevational view, partly 16¦ broken away, of the sensor shown in Figure 2;
17¦ Figure 4 is a sectional view taken on the line 18¦ 4-4 of Figure 3;
19¦ Figure 5 is an elevational view of a detail as 20 ¦ viewed in the direction of the arrows 5-5 of Figure 4; and 21¦ Figure 6 is a view similar to Figure 2, but 22¦ illustrating a modified form of the invention.
24¦ A sensor constructed in accordance with the 251 invention is adapted to be enclosed within a sturdy casing or 26¦ housing 1 having flanges 2 provided with openings for the 27 ¦accommodation of screws or the like (not shown) to mount 28¦ the housing at a suitable lo-ation on and relative to the 2~ ¦longitudinal axis of a vehicle. A bushing 3 fits within 3~ ¦ and closes an opening formed in the housing 1 and accommodates ~ 72~
1¦ an insulated cable ~ containing electrical wiring -to be 21 described hereinafter. The housing 1 has a cavity therein 3 for the accommodation of a sensor.
51 A sensor constructed according to the embodiment shown in Figures 2~5 comprises a cylindrical body 5 formed of 7 electrically insulating material. The body 5 has a bore 6 81 closed at one end by a wall 7 provided with a pair of 9 diametrically opposed openings 8 therein which communicate
10 with the bore 6. The opposite end of the bore 6 is open.
11 Adjacent the closed end of the bore the latter is provided
12¦ with a pair of longitudinally extending diametrically opposed
13¦ ribs 9 each of which has a groove 10 therein.
'` 141 Fitted into the bore 6 and seated against the end 16¦ wall 7 is an elongate sleeve 11 having a cylindrical bore 12 17 ¦ extending therethrough. The sleeve 11 is longer than the body 18 5 and that part of the sleeve which extends into the bore 6 19¦ has diametrically opposed, radially projecting ribs 13 that are fitted into the grooves 10 to preclude rotation of the 21 sleeve 11 relative to the body 5.
23 Accommodated in the bore 12 and seated at one end 241 against the end wall 7 is a biasing spring 14 having a prede-2B¦ termined capacity. Also accommodated in the bore 12 is a 26¦ biasing mass 15 having a predetermined weight and comprising 27 ¦ a preferably metallic body 16 that is both slidably and ro-28¦ tatably received in the bore 12. The body 16 terminates at 2~ one end in a reduced diameter extension 17 fitted into the ~ol spring 14 and which forms a shoulder 18 against which the :
1 ¦spring 14 seats. The opposite end of the body 16 also 2 ¦terminates in an e].ongate, reduced diameter extension l9 3 ¦fitted at its free end with an electrically insulative cap 20.
4 l That end of the sleeve 11 which projects beyond 61 the body 5 terminates in an annular outer skirt 22. Adjacent r ¦ the skirt is a reduced diameter, annular neck 23 that is 8 accommodated in the bore 6. The skirt 22 is threaded to 9 accommodate a correspondingly threaded plug 24 having an annular groove 25 therein in which is fitted a preferably ll glass cylinder 26 form.ing a tubular bore or passage 27 having 12¦ a smooth surface. The cylinder 26 extends inwardly of the 13¦ sleeve ll and beyond the plug a distance sufficient to be l4 received in and supported by the neck 23.
16 Accommodated in the bore 27 of the cylinder 26 17 is a preferably spherical sensing mass 29 formed of an 18 electrically conductive, low expansion metal. The mass 29 l9 normally seats on a semi-spherical surface 30 formed at the inner end of the plug 24. A spherical mass is preferred to 21 a cylindrical mass, for example, because a spherical mass 22 can roll and thus is much less susceptible to friction forces, and also because a cylindrical mass can cock causing major changes in fluid flow resistance. Both of these effects give rise to erratic behavior.
27 In the embodiment shown in Figure 2, the diameters 28 of the bore 27 and of the mass 29 are chosen to establish a clearance 31 bet.ween them of such size as to provide for inertial flow of fluid (air or other gas) through the ::
1 clearance for the purposes of damping movement of the mass 21 relative to the cylinder. Such inertial fluid flow results in 3 a sensor having a high velocity chanye for short duration 41 pulses and thus provides additional protection against in-51 advertent actuation of a passenger restraining device due to 6¦ short lived pulses caused by breakaway poles or hammer blows, 7 for example.
I Between its ends the sleeve 11 is provided with a pair of diametrically opposed slots 35 for the accommodation of electrically conductive switch blades 36 having bowed 12¦ contact portions 37 spaced apart from and confronting one 13 another and forming normally open contacts. The blades 36
'` 141 Fitted into the bore 6 and seated against the end 16¦ wall 7 is an elongate sleeve 11 having a cylindrical bore 12 17 ¦ extending therethrough. The sleeve 11 is longer than the body 18 5 and that part of the sleeve which extends into the bore 6 19¦ has diametrically opposed, radially projecting ribs 13 that are fitted into the grooves 10 to preclude rotation of the 21 sleeve 11 relative to the body 5.
23 Accommodated in the bore 12 and seated at one end 241 against the end wall 7 is a biasing spring 14 having a prede-2B¦ termined capacity. Also accommodated in the bore 12 is a 26¦ biasing mass 15 having a predetermined weight and comprising 27 ¦ a preferably metallic body 16 that is both slidably and ro-28¦ tatably received in the bore 12. The body 16 terminates at 2~ one end in a reduced diameter extension 17 fitted into the ~ol spring 14 and which forms a shoulder 18 against which the :
1 ¦spring 14 seats. The opposite end of the body 16 also 2 ¦terminates in an e].ongate, reduced diameter extension l9 3 ¦fitted at its free end with an electrically insulative cap 20.
4 l That end of the sleeve 11 which projects beyond 61 the body 5 terminates in an annular outer skirt 22. Adjacent r ¦ the skirt is a reduced diameter, annular neck 23 that is 8 accommodated in the bore 6. The skirt 22 is threaded to 9 accommodate a correspondingly threaded plug 24 having an annular groove 25 therein in which is fitted a preferably ll glass cylinder 26 form.ing a tubular bore or passage 27 having 12¦ a smooth surface. The cylinder 26 extends inwardly of the 13¦ sleeve ll and beyond the plug a distance sufficient to be l4 received in and supported by the neck 23.
16 Accommodated in the bore 27 of the cylinder 26 17 is a preferably spherical sensing mass 29 formed of an 18 electrically conductive, low expansion metal. The mass 29 l9 normally seats on a semi-spherical surface 30 formed at the inner end of the plug 24. A spherical mass is preferred to 21 a cylindrical mass, for example, because a spherical mass 22 can roll and thus is much less susceptible to friction forces, and also because a cylindrical mass can cock causing major changes in fluid flow resistance. Both of these effects give rise to erratic behavior.
27 In the embodiment shown in Figure 2, the diameters 28 of the bore 27 and of the mass 29 are chosen to establish a clearance 31 bet.ween them of such size as to provide for inertial flow of fluid (air or other gas) through the ::
1 clearance for the purposes of damping movement of the mass 21 relative to the cylinder. Such inertial fluid flow results in 3 a sensor having a high velocity chanye for short duration 41 pulses and thus provides additional protection against in-51 advertent actuation of a passenger restraining device due to 6¦ short lived pulses caused by breakaway poles or hammer blows, 7 for example.
I Between its ends the sleeve 11 is provided with a pair of diametrically opposed slots 35 for the accommodation of electrically conductive switch blades 36 having bowed 12¦ contact portions 37 spaced apart from and confronting one 13 another and forming normally open contacts. The blades 36
14 ¦ have corresponding free ends 38 at one end of the slots 35
15¦ which rest upon the neck 23 of the sleeve 11. Encircling the
16¦ ends 38 of the contact blaaes is an elastic band 39 which
17 ¦ yieldably maintains the ends of the conductive blades against
18 the neck. Adjacent the opposite end of the slots 35 the
19¦ conductive blades extend through the grooves 10 and end in
20 ¦ terminals 40 which project through the opening ~. One of the
21¦ terminals 40 is adapted for connection by a conductor 41 to
22 ground through an energy source such as a battery 42, and
23 the other terminal 40 is adapted for connection by a conductor 241 43 to an operator 44 of known construction that is operable to activate a passenger restraining instrumentality 45 such as an 26¦ inflatable airbag. The terminals 40 are flexible and may be 27 ¦ bent from the positions shown in Figure 2 so as to extend 28¦ through the bushing 3 and be connected to the conductors 41 2~ and 43 which are within the cable 4. .
~ol ':', ' , : .
.
1 ¦ ~t least one side of the sleeve 11 is provided 2 ¦wi~h a flattened surface ~6 that is substantially tangential 3 ¦to the inner surface of the bore 12. Fixed to the flattened ¦surface 46 is a plate 47 in which is formed a slot 48. The 5 ¦slot has a linear portion 49 which extends longitudinally of 6 ¦the bore 12 and communicates with a plurality of sinuous or 71 zig-zag slot portions 50,51, and 52. In the disclosed embodi-81 ment, the slot portion 50 extends at an angle of about 45 9 from the slot portion 49, the portion 51 extends at an angle of about 90 to the portion 50, and the slot portion 52 11 extends at an angle of about 90 to the slot portion 51. The 12¦ angularity of the slot portions may be different from that 13 specified.
15¦ The sleeve 11 is provided with an elongate, linear 16 slot 53 of greater width than that of the slot 49 and extend-17¦ ing parallel to the longitudinal axis of the bore 12. The 18¦ slot 53 communicates with the bore 12.
20¦ Fixed to the biasing mass 16 and projecting 21 laterally therefrom through the slot 53 and into the slot 49 22¦ is a pin 54. The pin 54 is slidable longitudinally of the 23 slot 49 and is capable of following the sinuous path formed by : 241 the slot portions 48-52. Since the body 16 is rotatable as 25¦ well as linearly movable wi-thin the bore 12, movement of the 26¦ pin 55 longitudinally of the slot 49 will cause the body to 27 ¦ be oscillated according to the path defined by the slot 49.
28¦ The slot 49 and the pin 54 constitute means for damping 20¦ movements of the biasing mass 16.
~501 1 The embodiment of the invention shown in Figure 6 21 is the same as that described earlier, except for the 3 differences noted below.
The plug 24a (corresponding -to the plug 24) has 6 a bore 56 in communication with a sharp edged orifice 57, 7 thereby forming an air passageway through the plug 24a. The diameters of the bore 27 and the mass 29 are virtually the 9 same, thereby limiting -the clearance 31a between the bore 27 and the mass 29 to an amount just sufficient to enable movement 11 of the mass within the bore and to minimize fluid flow between 12 bore 27 and the mass 29. To minimize the possibility of the 13¦ entry of foreign matter into the orifice 57, an air permeable 14 ¦ membrane 58 is adhered to and covers the open end of the 151 skirt 22.
17¦ To condition either of the two embodiments of 18¦ sensors disclosed herein for operation, it is fitted into 19¦ the cavity of the casing 1 and the terminals 40 connected to 20 ¦ the conductors 41 and 43. The cavity within the casing 1 is 21 of such size as to maintain the body 5 and the sleeve 11 in 22¦ assembled relation. The casing then may be bolted or otherwise secured to some portion of a vehicle with the longitudinal axis
~ol ':', ' , : .
.
1 ¦ ~t least one side of the sleeve 11 is provided 2 ¦wi~h a flattened surface ~6 that is substantially tangential 3 ¦to the inner surface of the bore 12. Fixed to the flattened ¦surface 46 is a plate 47 in which is formed a slot 48. The 5 ¦slot has a linear portion 49 which extends longitudinally of 6 ¦the bore 12 and communicates with a plurality of sinuous or 71 zig-zag slot portions 50,51, and 52. In the disclosed embodi-81 ment, the slot portion 50 extends at an angle of about 45 9 from the slot portion 49, the portion 51 extends at an angle of about 90 to the portion 50, and the slot portion 52 11 extends at an angle of about 90 to the slot portion 51. The 12¦ angularity of the slot portions may be different from that 13 specified.
15¦ The sleeve 11 is provided with an elongate, linear 16 slot 53 of greater width than that of the slot 49 and extend-17¦ ing parallel to the longitudinal axis of the bore 12. The 18¦ slot 53 communicates with the bore 12.
20¦ Fixed to the biasing mass 16 and projecting 21 laterally therefrom through the slot 53 and into the slot 49 22¦ is a pin 54. The pin 54 is slidable longitudinally of the 23 slot 49 and is capable of following the sinuous path formed by : 241 the slot portions 48-52. Since the body 16 is rotatable as 25¦ well as linearly movable wi-thin the bore 12, movement of the 26¦ pin 55 longitudinally of the slot 49 will cause the body to 27 ¦ be oscillated according to the path defined by the slot 49.
28¦ The slot 49 and the pin 54 constitute means for damping 20¦ movements of the biasing mass 16.
~501 1 The embodiment of the invention shown in Figure 6 21 is the same as that described earlier, except for the 3 differences noted below.
The plug 24a (corresponding -to the plug 24) has 6 a bore 56 in communication with a sharp edged orifice 57, 7 thereby forming an air passageway through the plug 24a. The diameters of the bore 27 and the mass 29 are virtually the 9 same, thereby limiting -the clearance 31a between the bore 27 and the mass 29 to an amount just sufficient to enable movement 11 of the mass within the bore and to minimize fluid flow between 12 bore 27 and the mass 29. To minimize the possibility of the 13¦ entry of foreign matter into the orifice 57, an air permeable 14 ¦ membrane 58 is adhered to and covers the open end of the 151 skirt 22.
17¦ To condition either of the two embodiments of 18¦ sensors disclosed herein for operation, it is fitted into 19¦ the cavity of the casing 1 and the terminals 40 connected to 20 ¦ the conductors 41 and 43. The cavity within the casing 1 is 21 of such size as to maintain the body 5 and the sleeve 11 in 22¦ assembled relation. The casing then may be bolted or otherwise secured to some portion of a vehicle with the longitudinal axis
24¦ of the sleeve 11 substantially parallel to the longitudinal 251 axis of the vehicle. If the casing is mounted at some frontal 26¦ portion of the vehicle, such as the bumperr a fender, or the 27 ¦ radiator the characteristics of the sensor will be different 28¦ from one that is mounted on the vehicle's firewall, as will 2 ~ be explained.
:' 1¦ ~ sensor corresponding to -tha-t disclose~ in Figure 2 2 is adapted to be mounted on the Eirewall of a vehicle 31 traveling in the direction of the arrow 60 (Figure 2).
4 ¦Deceleration of the vehicle, if suEficiently abrupt, will subject the bias mass 16 and the sensing mass 29 to an 61 acceleration pulse in the direction of the arrow 60. If 7 the acceleration pulse is sufficient to overcome the force 8 of the spring 14 the bias mass 16 will move in the direction 9 of the arrow 60, thereby disengaging the sensing mass 29 so as to enable the latter also to move in the direction of the llj arrow 60. The capacity of the spring should be such that an 12¦ acceleration pulse must exceed a predetermined threshold, such 13 as 3 Gs, before the bias mass 16 is capable of moving relative 14¦ to the sleeve 11. However, the capacity of the particular spring 14 selected may be varied to achieve optimum results.
1~ 1 If the acceleration pulse is of such magnitude as 18¦ to enable the bias mass 16 to overcome the force of the spring 19¦ 14, and is of sufficient duration, linear movement of the 20 ¦ bias mass can be quite rapid, and could be sufficiently rapid 21¦ to cause the mass to bottom on the wall 7 and rebound. In 221 the present construction, however, unrestricted linear movement 23 of the bias mass 16 may continue only until such time as the 241 pin 54 reaches the angular slot portion 50, whereupon the mass
:' 1¦ ~ sensor corresponding to -tha-t disclose~ in Figure 2 2 is adapted to be mounted on the Eirewall of a vehicle 31 traveling in the direction of the arrow 60 (Figure 2).
4 ¦Deceleration of the vehicle, if suEficiently abrupt, will subject the bias mass 16 and the sensing mass 29 to an 61 acceleration pulse in the direction of the arrow 60. If 7 the acceleration pulse is sufficient to overcome the force 8 of the spring 14 the bias mass 16 will move in the direction 9 of the arrow 60, thereby disengaging the sensing mass 29 so as to enable the latter also to move in the direction of the llj arrow 60. The capacity of the spring should be such that an 12¦ acceleration pulse must exceed a predetermined threshold, such 13 as 3 Gs, before the bias mass 16 is capable of moving relative 14¦ to the sleeve 11. However, the capacity of the particular spring 14 selected may be varied to achieve optimum results.
1~ 1 If the acceleration pulse is of such magnitude as 18¦ to enable the bias mass 16 to overcome the force of the spring 19¦ 14, and is of sufficient duration, linear movement of the 20 ¦ bias mass can be quite rapid, and could be sufficiently rapid 21¦ to cause the mass to bottom on the wall 7 and rebound. In 221 the present construction, however, unrestricted linear movement 23 of the bias mass 16 may continue only until such time as the 241 pin 54 reaches the angular slot portion 50, whereupon the mass
25 1 16 is forced to rotate in one direction as it continues to move
26¦ toward the wall 7. As the pin 54 approaches the slot portion
27 ¦ 51, such rotation of the mass 16 terminates and it is rotated 2~ ¦ in the opposite direction. In this manner the kinetic energy 2~ ¦ of the bias mass 16 is partially dissipated and movement of ~0 ¦ the mass is damped. It is possible that the bias mass 16 may ~ '7~
1 ¦be subjected to an acceleration pulse of such magnitude and 2 ¦duration that the mass will bottom on the wall 7 and 3 rebound notwi-thstanding damping of its movemen-t. In this 4 event, rebounding movement of the mass also is damped by the cooperation of the pin 54 and the slot 48.
71 When the bias mass 16 is subjected to an 81 acceleration pulse sufficient to effect disengagement of the 9 latter from the sensing mass 29, the latter mass, being sub~
jected to the same acceleration pulse, is enabled to move in 11 the same direction as the bias mass 16. After sligh-t movement 12 of the sensing mass ~9 off its seat 24, a partial vacuum is 13¦ formed between the mass and the seat. A pressure differential 1~¦ thus is created across the sensing mass and produces a damping force which opposes further movement of the mass. Gradually, 161 however, fluid will leak past the mass 29 at a rate that is 17 determined by the size of the clearance 31. Preferably, the 18 clearance is of such size as to provide for inertial flow 19 of the fluid through the clearance 31, rather than viscous flow, and to provide the desired rate of longitudinal movement 21 of the sensing mass as explained in the aforementioned patent.
23 If the acceleration pulse is of sufficient 24 magnitude and duration, the mass 29 eventually will move to a position in which it bridges the contacts 37. The diameter 26 of the mass 29 is greater than the spacing between the contacts 27 37 thereby assuring good contact between the blades and the
1 ¦be subjected to an acceleration pulse of such magnitude and 2 ¦duration that the mass will bottom on the wall 7 and 3 rebound notwi-thstanding damping of its movemen-t. In this 4 event, rebounding movement of the mass also is damped by the cooperation of the pin 54 and the slot 48.
71 When the bias mass 16 is subjected to an 81 acceleration pulse sufficient to effect disengagement of the 9 latter from the sensing mass 29, the latter mass, being sub~
jected to the same acceleration pulse, is enabled to move in 11 the same direction as the bias mass 16. After sligh-t movement 12 of the sensing mass ~9 off its seat 24, a partial vacuum is 13¦ formed between the mass and the seat. A pressure differential 1~¦ thus is created across the sensing mass and produces a damping force which opposes further movement of the mass. Gradually, 161 however, fluid will leak past the mass 29 at a rate that is 17 determined by the size of the clearance 31. Preferably, the 18 clearance is of such size as to provide for inertial flow 19 of the fluid through the clearance 31, rather than viscous flow, and to provide the desired rate of longitudinal movement 21 of the sensing mass as explained in the aforementioned patent.
23 If the acceleration pulse is of sufficient 24 magnitude and duration, the mass 29 eventually will move to a position in which it bridges the contacts 37. The diameter 26 of the mass 29 is greater than the spacing between the contacts 27 37 thereby assuring good contact between the blades and the
28 mass 29 to effect closing of the switch thus formed by the 2~ blades and mass to actuate the mechanism 44 and inflate the ~0 airbag 45. To ensure against bouncing or rebounding of the 1¦ blades 37 as they are engaged by the mass 29, the elastic 2¦ band 39 imposes a yiel~able force on the blades to restrain 3 their separa-tion and maintain them in firm engagement with the 41 mass 29.
61 In the construction illustrated in Figure 2, the 7 length of the linear slot portion 49 is such that, by the 8 time the mass 16 has moved a distance to enable the pin 54 9¦ to enter the slot portion 50, the bias mass also has moved a distance sufficient to enable the sensing mass 29 to engage 11 and bridge the contacts 37. This is the arrangement preferred 12 when the sensor is mounted on a vehicle's firewall.
14 If the sensor is to be mounted on an energy absorbing portion of a vehicle, such as the front bumper or 16¦ fender, a slightly different relationship between the bias 17 ¦ mass 16 and its damping means is preferred so as to delay 18¦ initiation of the inflation of the airbag. This effect may 19¦ be achieved by shortening the length of the linear slot portion 20¦ 49, i.e., locating the first angular slot portion 50 closer 21¦ to the initial position of the sensing mass 29. In such an 22¦ arrangement damping of the movement of the bias mass 16 23 commences prior to the time that it is moved a distance 24¦ sufficient to permit engagement of the mass 29 with the 251 contacts 37. In such a construction the acceleration pulse 28¦ not only must exceed the force of the spring 14, but also 27 ¦ must be of sufficient duration to enable movement of the 2B¦ bias mass 16 a distance great enough to permit movement of 2~1 the sensing mass 29 into engagement with the contacts 37.
~ol This arrangement makes it possible to distinguish be-tweQn ~: . ~ . , .: , l ¦crashes necessitating deployment of the protective device and 2 other, shor-t dura-tion pulses.
4 The operation of the sensor embodiment illustrated in Figure 6 is quite similar to that of the previously des-61 cribed embodiment with the exceptLon that, in the modified 7 embodiment, movement of the sensing mass 29 is damped by 8 restricting the flow of fluid to the space between the mass 9 and the seat 30a by means of the sharp edge~ orifice 57. In the modified construction the clearance 31a between the mass 11 29 and the bore 27 is less than the clearance 31, and should 12 be just sufficient to enable movement of the mass 29 relative 13¦ to the cylinder 26, thereby assuring that the dominant damping 14¦ influence on the mass 29 is attributable to the fluid. The 15¦ flow characteristics of the fluid through the orifice , 16¦ preferably are inertial.
18¦ The ability to damp not only the movement of the 19 sensing mass 29, but also the bias mass 16, coupled with the 20 ¦ latter's ability to enable or disable free movement of the 21¦ sensing mass 29 into agreement with switch contacts, permits 22 sensors having greatly di~fering operating characteristics to 23 be produced. Thus, sensors constructed in accordance with the ~4 ¦ invention are capable of operation regardless of whether they 251 are mounted at frontal or rearward positions on a vehicle and 26¦ are effective to sense the need for operation of a passenger 27 ¦ protective device and initiate operation of such device in 28¦ sufficient time to provide protection for a vehicle occupant.
2~1 The disclosed embodiments are representative of ~q~7~
l ¦presently preferred forms of the invention, but are intended 2 ¦to be illustra-tive ra-ther than definitive. The invention is 1 deiined i the claims.
D
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2~
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~ I - 15 -
61 In the construction illustrated in Figure 2, the 7 length of the linear slot portion 49 is such that, by the 8 time the mass 16 has moved a distance to enable the pin 54 9¦ to enter the slot portion 50, the bias mass also has moved a distance sufficient to enable the sensing mass 29 to engage 11 and bridge the contacts 37. This is the arrangement preferred 12 when the sensor is mounted on a vehicle's firewall.
14 If the sensor is to be mounted on an energy absorbing portion of a vehicle, such as the front bumper or 16¦ fender, a slightly different relationship between the bias 17 ¦ mass 16 and its damping means is preferred so as to delay 18¦ initiation of the inflation of the airbag. This effect may 19¦ be achieved by shortening the length of the linear slot portion 20¦ 49, i.e., locating the first angular slot portion 50 closer 21¦ to the initial position of the sensing mass 29. In such an 22¦ arrangement damping of the movement of the bias mass 16 23 commences prior to the time that it is moved a distance 24¦ sufficient to permit engagement of the mass 29 with the 251 contacts 37. In such a construction the acceleration pulse 28¦ not only must exceed the force of the spring 14, but also 27 ¦ must be of sufficient duration to enable movement of the 2B¦ bias mass 16 a distance great enough to permit movement of 2~1 the sensing mass 29 into engagement with the contacts 37.
~ol This arrangement makes it possible to distinguish be-tweQn ~: . ~ . , .: , l ¦crashes necessitating deployment of the protective device and 2 other, shor-t dura-tion pulses.
4 The operation of the sensor embodiment illustrated in Figure 6 is quite similar to that of the previously des-61 cribed embodiment with the exceptLon that, in the modified 7 embodiment, movement of the sensing mass 29 is damped by 8 restricting the flow of fluid to the space between the mass 9 and the seat 30a by means of the sharp edge~ orifice 57. In the modified construction the clearance 31a between the mass 11 29 and the bore 27 is less than the clearance 31, and should 12 be just sufficient to enable movement of the mass 29 relative 13¦ to the cylinder 26, thereby assuring that the dominant damping 14¦ influence on the mass 29 is attributable to the fluid. The 15¦ flow characteristics of the fluid through the orifice , 16¦ preferably are inertial.
18¦ The ability to damp not only the movement of the 19 sensing mass 29, but also the bias mass 16, coupled with the 20 ¦ latter's ability to enable or disable free movement of the 21¦ sensing mass 29 into agreement with switch contacts, permits 22 sensors having greatly di~fering operating characteristics to 23 be produced. Thus, sensors constructed in accordance with the ~4 ¦ invention are capable of operation regardless of whether they 251 are mounted at frontal or rearward positions on a vehicle and 26¦ are effective to sense the need for operation of a passenger 27 ¦ protective device and initiate operation of such device in 28¦ sufficient time to provide protection for a vehicle occupant.
2~1 The disclosed embodiments are representative of ~q~7~
l ¦presently preferred forms of the invention, but are intended 2 ¦to be illustra-tive ra-ther than definitive. The invention is 1 deiined i the claims.
D
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Claims (28)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A sensor construction comprising a body member provided with a tubular passage having a bore; a sensing mass accommodated in said bore and movable in one direction from an initial position in response to acceleration above a predetermined threshold of said body member in the oppo-site direction; a bias mass mounted in said body member for movement in response to said acceleration of the latter from a normal position in which it engages said sensing mass to a second position spaced from said sensing mass;
yieldable means yieldably urging said bias mass toward said normal position; and means for damping said movement of said bias mass from said normal position toward said second position.
yieldable means yieldably urging said bias mass toward said normal position; and means for damping said movement of said bias mass from said normal position toward said second position.
2. A sensor construction according to claim 1 wherein said damping means includes means effective to damp said movement of said bias mass only after the latter has moved toward said second position a distance sufficient to effect disengagement of said bias mass and said sensing mass.
3. A sensor construction according to claim 1 wherein said damping means is effective to damp movement of said bias mass in a direction from said second position toward said normal position.
4. A sensor construction according to claim 1 includ-ing means for damping movement of said sensing mass from said initial position.
5. A sensor construction according to claim 1 wherein said passage contains a fluid and wherein movement of said sensing mass is damped by said fluid.
6. A sensor construction according to claim 5 wherein said fluid is a gas.
7. A sensor construction according to claim 6 wherein said gas is air.
8. A sensor construction according to claim 1 wherein said damping means comprises cooperable means carried by said body and by said bias mass for retarding the rate of movement of the latter in a direction toward said second position.
9. A sensor construction according to claim 1 wherein said damping means comprises cooperable means carried by said body and by said bias means for translating linear movement of the latter into rotary movement.
10. A sensor construction according to claim 9 wherein said cooperable means comprises a pin accommodated in a slot.
11. A sensor construction according to claim 10 where-in said slot is formed in said body and said pin projects from said bias mass.
12. A sensor construction according to claim 11 wherein said slot has a first portion extending parallel to the direction of movement of said bias mass toward said second position and communicating with a second portion extending laterally of said first portion.
13. A sensor construction according to claim 12 where-in said slot has additional portions which define with said second portion a zig-zag path.
14. A sensor construction adapted for mounting on a vehicle or the like having an instrumentality to be operated in response to acceleration of said vehicle above a predetermined threshold, said sensor comprising a body member having a tubular passage; a sensing mass mounted in said passage for movement in response to acceleration of said vehicle from an initial position toward a second posi-tion in which said sensing mass initiates operation of said instrumentality; biasing means exerting a predetermined, yieldable force on said sensing mass restraining movement of the latter from said initial position until said pre-determined force is overcome by acceleration whereupon said biasing means is movable relative to said body member and said sensing mass; and means responsive to movement of said biasing means for damping such movement.
15. A sensor construction according to claim 14 where-in said passage contains a fluid and wherein movement of said sensing mass is damped by said fluid.
16. A sensor construction according to claim 15 where-in said fluid is a gas.
17. A sensor construction according to claim 16 where-in said gas is air.
18. A sensor construction according to claim 14 where-in said passage contains a fluid and wherein there is a clearance between said passage and said sensing mass through which said fluid flows in response to movement of said sens-ing mass.
19. A sensor construction according to claim 14 wherein said passage contains a fluid and has an orifice in com-munication with said passage adjacent that end of the passage occupied by said sensing mass when the latter is in its initial position, said orifice providing a passage-way for said fluid into said passage in response to move-ment of said sensing means from its initial position.
20. A sensor construction according to claim 14 wherein said sensing mass is spherical.
21. A sensor construction according to claim 14 where-in said sensing mass is formed of electrically conductive material.
22. A sensor construction according to claim 14 where-in said biasing means includes a mass member and wherein said damping means comprises cooperative means carried by said body member and said mass member for translating linear movement of the latter into rotary movement thereof.
23. A sensor construction according to claim 22 where-in said cooperative means comprises a slot in one of said members and a pin on the other of said members accommodated in said slot.
24. A sensor construction according to claim 14 including actuating means adapted for connection to said instrumentality and extending into said passage for engage-ment by said sensing mass in response to movement of the latter a predetermined distance from its initial position.
25. A sensor construction according to claim 24 wherein said actuating means comprises electrically con-ductive, normally open switch means engageable by said sensing mass.
26. A sensor construction according to claim 25 wherein said sensing mass is formed of electrically con-ductive material.
27. A sensor construction according to claim 25 wherein said switch means includes spaced apart contacts, the spacing between said contacts being less than the corresponding dimension of said sensing mass.
28. A sensor construction according to claim 25 in-cluding means yieldably opposing separation of said con-tacts.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA353,957A CA1108721A (en) | 1980-06-13 | 1980-06-13 | Velocity change sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA353,957A CA1108721A (en) | 1980-06-13 | 1980-06-13 | Velocity change sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1108721A true CA1108721A (en) | 1981-09-08 |
Family
ID=4117177
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA353,957A Expired CA1108721A (en) | 1980-06-13 | 1980-06-13 | Velocity change sensor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1108721A (en) |
-
1980
- 1980-06-13 CA CA353,957A patent/CA1108721A/en not_active Expired
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