SOLENOID INTERFACE FOR A MANUALLY OPERATED DEACCELERATION WARNING SYSTEM

Abstract: The warning system employs relay (120) isolation between a control loop containing a driver controlled switch (110) and an operating loop (148) for activating the braking lamps (114). The relay bypasses the brake pedal switch (146) for use during energy recapture or downshift deacceleration for manually flashing the braking lamps. Termination transients within the control loop, the relay structure, and operating loop cause electric, mechanical and thermal lags which prolong the trailing edge of the flash beyond the release of the manual switch. This post-release illumination assures that the warning flash cycle will have at least a minimum duration independently of the depression period of the switch (110).

Description: DESCRIPTION SOLENOID INTERFACE FOR A MANUALLY OPERATED DEACCELERATION WARNING SYSTEM TECHNICAL FIELD This invention relates to a double loop deacceleration warning systems for vehicles, and more particularly to such systems employing a solenoid interface between the driver control loop and the lamp operating loop. BACKGROUND Heretofore, single loop deacceleration warning systems have been provided on automotive vehicles permitting the driver to indicate deacceleration while downshifting -see ϋS4,105,994 to Chicoine, US4,162,384 to Chicoine, and US4,158,833 to Chicoine. These manually operated switches were in direct series connection with the braking lamps, without an interface circuit therebetween. The contacts of the switch were therefore exposed to interruption arcing by the heavy lamp current (typically two amperes or more) . As this prior art warning system aged, oxide buildup on the switch contacts sometimes caused a high impedance connection therebetween. The resulting voltage loss across the switch subtracted from the actual operating voltage appearing across the braking lamps, reducing the lamp intensity from full brillance. Variations in contact pressure as applied by the driver, further aggravated the unreliability impedance of the oxidized contacts. In addition, the rate of operation dictated by the driver varied producing corresponding, but undesireable, variations in the lamp intensity and the activation or flash period. A rapid flash is less noticeable by other drivers; and if the flash period is too short, the braking lamps are prematurely deactivated and fail to reach maximum brightness in the limited time permitted by the driver. er-τ-ι SUMMARY It is therefore an object of this invention to provide a double loop vehicle deacceleration warning system in which the manually operated switch is electrically isolated from the braking lamp activation current. It is another object of this invention to provide a double loop vehicle deacceleration warning system in which contact arcing and oxidation is minimized in the manually operated switch. It is a further object of this invention to provide a vehicle deacceleration warning system which is inexpensive, may be easily retrofitted, has a longer life, and provides increased deacceleration safety. It is a further object of this invention to provide a vehicle deacceleration warning system in which premature deactivation of the warning lamps is avoided. It is a further object of this invention to provide a vehicle deacceleration warning system in which the warning lamps remain activated at operational intensity for a predetermined period after the manually operated switch is released. It is a further object of this invention to provide a vehicle deacceleration warning system in which stored energy prolongs the activation of the warning lamps after the switch has been released by the driver. It is a further object of this invention to provide a double loop warning system which provides audio feedback to the driver indicating the status of the operating loop. OMPI BRIEF DESCRIPTION OF THE DRAWING Further objects and advantages of the present invention and the operation of the interface relay, will become apparent from the following detailed description and drawing in which: Figure 1 is a schematic diagram of the deacceleration warning system mounted within a vehicle; Figure 2 is a timing diagram of the flashing cycle of the warning system of Figure 1 showing the intensity maintaining effect of stored energy; Figure 3 is a schematic diagram of an override embodiment in which the braking lamps may be manually flashed during conventional pedal braking; and Figure 4 is an exploded view of a control knob and lever showing the internal structure of an embodiment of the manual switch mounted thereon. OMPI DETAILED DESCRIPTION Deacceleration warning system 100 (see Figure 1) is formed by a manually operated switch 110, SPST relay 112 responsive to switch 110, and warning lamps 114 activated by relay 112. Switch 110 may be any suitable normally open, press-to-close switch, such as a pushbutton, disc, or touch switch, positioned within the drivers zone of control. Switch 110 may be mounted on the deacceleration control lever 116 and adjusted to the desired height and azmith as discribed in the aforementioned Chicoine patents. During deacceleration, the driver presses switch 110 permitting control current I:coil to energize coil 120 of relay 112 displacing relay armature 122A. Relay, contacts 122S (stationary) and 122M (movable) snap close permitting lamp current I:lamp to activate warning lamps 114. Contacts 122 are normally open due the resilience of relay bias member 126. The magnetic field H.coil established within relay core 130 by I:coil overcomes the resilence of spring 126, permitting armature 122 to pivot causing relay contact 122M to move into engag ent with contact 122S. Iϊlamp in the operating loop immediately elevates the temperature of filaments 136 within lamps 114 causing them to incandesce. The power for both relay 112 and warning lamps 114 is provided from a suitable electric power source such as storage battery 140 through fusing device 142. Relay 112 bypasses the braking switch 146, which activates warning lamps 136 during brake pedal deacceleration. OMP As the driver release switch 110, Ircoil terminates causing contacts 122 to separate. I:lamp then terminates causing filaments 136 to cool and lose incandesce. The incandescence of lamps 114 is maintained beyond the release of manual switch 110 by a delay in the separation of contacts 122 due to the inductive lag of coil 120, the mechanical lag of relay 112, and the magnetic lag of core 130. The incandescence of lamps 114 is further maintained beyond the separation opening of relay contacts 122 by the inductive lag of the distributed inductance of warning lamp lead 148, the separation lag of contacts 122, and the thermal lag of filaments 136. As a consequence of these lag transients, lamps 114 are maintained at an operational brightness for at least the transient period required to dissipate the stored energy associated with each of the above factors. These lag transients prevent system 100 from responding to rapid switching cycles, which in the prior art device generated short, low intensity flashes. The lag transient period following relay closure is sufficient to activate lamps 114 at an operational brightness. Abhorted switching cycles in which switch 110 is— released prior to relay closure, is avoided by the tactile feedback cues generated by the snapping of switch 110. The snaps assist the driver in establishing a switching cadance in which switch 110 is not released until relay contacts 122 engage. The low value of control current I:coil through switch 110, minimizes arcing and oxide buildup on the switch contacts. Further, even if high impedance oxides do develope over time; the voltage lost across switch 110 is isolated by interface relay 112, from the operating voltage appearing across lamps 114. Arcing due to the heavier operating current I:lamp does not materially affect relay contacts 122, which are designed to withstand the spark impact. BRIGHTNESS MAINTAINING EFFECT OF THE STORED ENERGY The timing diagram of Figure 2 shows a complete warning flash cycle of system 100, revealing the cause and effects of the various transient lags, and time relationships of the stored energies which prolong the incandescence after switch 110 is released. lϊcoil is initiated (see Figure 2A) when switch 110 is depressed by the driver (t=0) . Ircoil rises through the low resistance control circuit developing the magnetic field H:coil around coil 114, and reaches a steady state value of a few millia peres (t=3) . Just prior to steady state conditions in the control loop, H:coil becomes strong enough to close relay contacts 122 (t=l). The driver maintains the low control loop resistance during driver depression period 246A (t=0 to t=5) . The driver releases switch 110 (t=5) , returning the control loop to the normal high impedance .condition. I:coil is maintained beyond t=5 by the inductance L:coil which discharges H:coil through the high impedance control circuit. The collapse of H:coil (t=5 to t=8) requires more time than the buildup of H:coil due to the high impedance of switch 110 during collapse. During H:coil collapse, the strength of weakening magnetic field H:coil becomes insufficient to hold contacts 122 closed against the tension of spring 126 (t=6) , permitting contacts 122 to separate and return to the open position (t=7) . . ■ __-"--i - ; . * _ -__ Z2- j£_._-_. i The strength of H:coil required to maintain contacts 122 closed (t=l to t=6) is much less than the strength to required to initially displace contact 122M into engagment with contact 122S. This mechanical effect is caused by the lower magnetic strengths of Hrcoil at the open position of contact 122M relative to the higher magnetic strength of H:coil at the closed position of contact 122M. A corresponding mechanical lag is generated in each flash cycle because the lower Hrcoil strength occurs at t=5, late during the collapse of Hrcoil, after switch 110 is released at t=5. A magnetic lag within ferrite core 130 further delays the actual separation of contacts 122 (t=7) , due to lingering characteristic of magnetism. The magnetic domains within core 130 do not return to the premagnetized state immediately upon the loss of the sustaining magnetic field Hrcoil. When relay contacts 122 close (t=7) , Irlamp rises rapidly in the operating circuit, opposed only by the distributed inductances of warning lamp supply lead 148. Irlamp reaches steady state at t=4, and maintains this maximum value until t=7 when relay contacts 122 separate. Contacts 122 remain closed during relay closed period 246B (from t=l) until the expiration of the inductive lag of coil 120, the mechanical lag of relay 112, and the magnetic lag of core 130. The temperature of lamps 116 increase in response to Irlamp, (see Figure 2C) causing filaments 136 to incandesce. At t=2, filaments 136 have reached a temperature sufficient to incandesce at an operating level within 3db of the maximum brightness. Operating brightness period 246C is maintained from the leading 3db power point (t=2) to the trailing 3db power point (t=8) , extending a substantially period beyond switch 110 release (t=5) . The rise of filament temperature is responsive to Irlamp resistance losses within filaments 136; and is not symmetrical with the decline of filament temperature which is due to the mutual effect of loss of Irlamp and cooling through radiation. Energy to maintain incandescence after switch release is supplied by electrical and thermal transients within ' system 100. Maximum brightness is maintained from switch release (t=5) to relay open (t=7) by the full Irlamp. A diminishing but operable brightness is maintained above the 3db level from relay open (t=7) to the trailing 3db power point (t=9) by the distributed inductance lag of lead 148, the separation lag of contacts 122, and the finite time required for filaments 136 to cool from full emission level to he 3db emission level. The energy stored in the magnetic field of an inductance is proportional to the square of the current. The small value of the distributed inductance relative to Lrcoil is compensated for by the large value of Irlamp relative to the small value of lrcoil. In a typical automobile application, the operating current Irlamp may be several amperes; exceeding the milliampere level control current lrcoil by a factor of a thousand. Separation lag is caused by opposing plasma forces created by Irlamp during gap formation between contacts 122. Force and time are required to generate the ions accompanying contact separation in dc applications. OMPI f' '' * _*> ■ -*—n— WIPO These energy transients establish a fixed termination transient period (t=5 to t=9) which is beyond the control of the driver. Driver pressure period 246A may be increased by the driver to provide warning flashes of longer duration. However, the warning flash may not be shortened to less then the termination transient period (t-5 to t=9) no matter how fast the operator releases switch 110. Once relay contacts 122 close (t=l) , a definitive warning flash must follow having an operating brightness and a duration at least as long as the termination transient period. The energy transient period may be increased to provide a longer warning flash by adjusting the tension of spring 126. Spring 126 maintains contacts 122 in the normally open position and returns contacts 122 to the open position at contact separation (t=7) . Decreasing the tension of spring 126 will retard contact separation (t=7) as indicated by the arrow 250R, because the decreasing Hrcoil will overpower the tension and maintain contacts 122 closed for a longer period after switch 110 release. A lower tension caus.es a corresponding advance in the closure of relay 112 (t=l) which minimizes the possibility of an abhortive switch cycle which is too fast to energize relay 112. Ϊ OVERRIDE FLASHING SPDT relay 312 (see Figure 3) may be employed in a braking lamp override circuit 300 for permitting the driver to flash brake lamp 336 during conventional brake 5 pedal deacceleration. Relay armature 122A is shown in the resting position, engaging normally on contact 324. Voltage for activating lamps 336 is applied to armature 122A, across the moving contact 322M-stationary contact 324 engagement, to normally open brake pedal switch 346. 0 When brake switch is closed during brake pedal displacement, brake lamp 336 is activated. Brake pedal activations are typically long, continuous flashes. The driver can interrupt this flash with short brakes by repeatedly operating manual switch 310, causing .relay 312 5 to chatter. Armature 322A jumps back and forth between normally open contact 322S and normally closed contact 324. Lamp 336 is activated in either position of armature 322A; but re briefly deactivated during the motion period or flight time between stationary contacts. A flash 0 interruption is produced each time switch 310 is either pressed or released. Relay 312 interrupts the normal continuous braking flash during energization and also during de-energization. The interrruption time may be increased by employing a delay type relay for establishing 5 a more pronounced break in the warning flash. Delay relays have a spring tension and air gap specifically designed to maximize the flight time. In addition, these relays may employ a copper slug or sleeve around the coil which increases the switching time response. 0 OMPI VΛ, WIPO 01 During recapture of downshift deacceleration, braking switch 346 remains closed; and manual switch 310 is operated to move armature 322A and activate brake lamps 336. 05 If desired, flasher 350 may be installed in series in the operating loop to automatically break the operating current in order to flash brake lamps 114 while switch 110 is continuously depressed. During pedal braking, the driver has the option of not depressing switch 310 10 resulting in a single continuous warning flash of braking lamps 336; or of depressing switch 310 to energize flasher 350 resulting in a series of warning flashes. MANUAL SWITCH STRUCTURE In wafer switch structure 400 (see Figure 4.) , knob 15 406 is provided with a recess 408 for retaining a correspondingly shaped wafer assembly 412. Rigid base 418 is mounted within recess 408 by a suitable adhesive, and has. four locating tabs 420 for positioning miniature switch 410. Flexible top member 426 engages peripheral 20 shoulder 430 of base 418 for covering switch 410. Pin 434 extending downwardly from top member 426 operates switch 410 when top member 426 is pressed by the driver. A suitable decal containing control positions of lever 438 may be mounted on top member 426. Fusible lead 440 may be 25 employed for connecting switch 410 to the interface relay. The thinness of wafer structure 400 permits gear shift knobs to be easily retrofitted to provide manual deacceleration warnings. Alternatively, a one piece, resilient hollow knob may be employed for housing wafer 30 structure 400. 35 ( -P OM M P P iI CONCLUSION It will be apparent to those skilled in the art that the"objects of this invention have been achieved by providing a double loop warning system having a low current control loop, and a heavy duty operating loop with an interface relay therebetween. Clearly various changes may be made in the structure and embodiments shown herein without departing from the concept of the invention. Further, the features of each embodiment shown in the various Figures may be employed with the embodiments of the other Figures. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.

Claims: I claim as my invention 1. A manually operated vehicle deacceleration warning system having a control loop and an operating loop and an interface relay therebetween, comprisingr electrical power source means; a normally open manual switching means mounted within the control zone of the driver forming part of the control loop, and connected to the power source means for permitting a control current to flow in the control loop when manually closed by the driver; a coil of the interface relay forming part of the control loop, and connected in series between the manual switching means and the power source means for energization by the control current; contact means of the interface relay forming part of the operating loop, and responsive to the energization of the coil for permitting an operating current to flow in the operating loop; and warning lamp means forming part of the operating loop, and connected in series between the relay contacts and the power source means for being activated by the operating current. 2. The warning system of claim 1, wherein energy stored within the system during activation of the warning lamp means, prolongs the activation period of the lamp means to a time after the manual switching means has been restored to the normally open state by the driver and the relay contact means have separated for establishing a minimum lamp activation period independently of the length of time that the driver maintains the switching means in the closed position. 3. The warning system of claim 2, wherein the energy stored in the system for prolonging the lamp activation period includes the magnetic energy of the control current around the coil which maintains the relay contacts closed for a brief period after the driver has opened the manual switch. 4. The warning system of claim 3. wherein the energy stored in the system for prolonging the lamp activation period additionally includes the magnetic energy of the operating current across the relay contact means which maintains the operating current through the lamp means for a brief period after the relay contact means have separated. 5. The warning system of claim 4, wherein the warning lamp means is an incandescent light source means which emits light when hot, and the energy stored within the system for prolonging the activation period of the light source means additionally includes the thermal energy of the light source means which maintains the incandescence thereof after the the operating current therethrough has terminated. 6. The warning system of claim 5, wherein the relay contact means compriser at least one stationary contact; at least one movable contact in opposed and normally spaced relationship with the stationary contact; and resilient means for maintaining the contacts in the normally spaced relationship. f'l » -.^- M I ______ O_____ <- • ' ' • ■ r ~ - W 7. The warning system of claim 6, further comprisingr a ferrite core within the relay coil for supporting a magnetic field when the coil is energized which displaces the moving contact into engagment with the stationary contact, and for maintaining the engagment therebetween after the control current has terminated due to magnetic lag within the core. 8. The warning system of claim 6, further comprising a pedal braking lamp switch which connect the warning lamps to the electrical power source during pedal braking for causing the warning lamps to incandesce. 9. The warning system of claim 8, wherein the interface relay is a single pull-single throw relay having a pair of normally open contacts connected in bypass relationship with the pedal braking lamp switch for connecting the warning lamps to the electrical power . source when the manual switch is operated by the driver. 10. The warning system of claim 8, wherein the interface relay is a single pull-double throw relay having a normally open contact which is closed when the relay is energized for connecting the warning lamps to the electrical power source when the relay is energized, and a normally closed contact for connecting the electrical power source to the pedal braking switch when the relay is de-energized. 11. The warning system of claim 4, further comprising a flasher means serially connected in the operating loop for causing the lamp means to flash when the manual switch is maintained closed by the driver. UREA __ __ OMPI "" " -16- 12. A vehicle deacceleration warning circuit which is manually operated by the vehicle driver for activating braking lamps on the vehicle at an operable brightness for at least a predetermined minimume time, comprisingr a normally open, press to close switch which is manually operated by the driver for permitting a control current to flow; a solenoid means having a coil for generating a magnetic field in response to the control current, and a pair of normally open contacts which close in response to the magnetic field of the coil to permit an operating current to flow and activate the braking lamps causing them to incandesce; whereby once the switch is pressed close by. the operator, the braking lamps incandesce at an operable level while the magnetic fields associated with the • control current and the operating current collapse and the lamp filament cool below the operable level of incandescence. ' 13. The circuit of claim 12, wherein the relay further comprises: a tension means for biasing the solenoid contacts open prior to the initiation of the control current, and for returning the solenoid contacts to the open position after release of the switch by the driver. 14. The circuit of claim 13, wherein open bias of the tension means is overcome by the magnetic field of the control current prior to steady state control current conditions, and the open bias of the tension means overcomes the decreasing magnetic field 15. The circuit of claim 14, wherein the tension means is adjustable to advance or delay the closing and openning of the relay contacts. .O

Inventors: CHICOINE G
Applicants: CHICOINE G
Application year: 1981
Main classification: B60Q1
IPC codes: B60Q1