CUT-OFF SWITCH FOR VEHICLE PROPULSION SYSTEM

Abstract: An automatic cut-off switch for a motor cycle engine, having a lean detector (36) connected in a circuit, the signal from the lean detector (36) causes a capacitor (52) to charge while said lean detector (36) detects a lean of a predetermined value from a reference position, the capacitor (52) upon reaching a voltage determined by the setting of a variable resistor (58), switches a silicon-controlled rectifier (56) which in turn switches a relay (54) to open-circuit the ignition circuit (62) of the motor cycle engine. The lean detector (36) consists of a pendulum (18) supported by a frame (12), the pendulum capable of limited movement in a plane perpendicular to a reference plane and having apertures (26, 28) which in extreme positions corresponding to predetermined lean values allow light from a light-emitting diode (38) to be received by a phototransistor (40), thereby providing the signal.

Description: TITLE: CUT-OFF SWITCH FOR VEHICLE PROPULSION SYSTEM This invention relates to a cut-off switch * arrangement for th.e propulsion system of a -vehicle,• and in particular relates to an automatic cut-off switch for the engine of a motor cycle. Motor cycles are inherently prone to instability; they may fall to the ground when they come into contact with another vehicle or obstacle on the road, when they skid on a wet and/or greasy surface, and when they are ridden around a curve in a road in the wrong manner or a the wrong speed. In many situations where a motor cycle falls to the ground the rider is unharmed or only slightly injured. To avoid further injury or damage to the motor cycle, it is necessary to stop the motor cycle's engine if, as is often the case, the engine continu to operate after the motor cycle has fallen, and in such cases the transmission is usually also still engaged. If the engine is not able to be stopped the motor cycle may move erratically away from the scene of the fall, and be further damaged, or if the rider is pinned beneath the fallen motor cycle, it may harm the rider by striking him with the spinning rear wheel or the moving chain, or as it spins on its^crash bars. In any of these situations, there is also a danger from fire. The motor cycle's engine may also be damaged if the throttle CIvIPI y røro remains operative. Most modern motor cycles are fitted with a manual cut-off switch (known as a 'kill switch* , which is normally fitted to the handlebars, and is intended to be operated- by the rider to stop the engine in the situations described in the previous paragraph. However, in many such emergency situations the switch is virtually useless because. the motor cycle rider cannot react quickly enough to operate it, or cannot reach it to operate it. There have been proposals for an automatic cut-off switch (an automatic 'kill switch') which will operate to stop an engine automatically in an emergency situation. One such proposed switch is described on P a 9 e 107 of the June 1970 edition of the magazine 'ELECTRONICS Australia'. The switch is a mercury switch wherein at a certain amount of tilt of the motor cycle to which the switch is fitted, mercury trapped in a tube will complete a circuit by touching two contacts, shorting the ignition coil to earth, stopping the engine 'almost immediately'. Another type of automatic cut-off switch is the emergency shut off switch fitted to 1978 model Yamaha 1100E motor cycles, but apparently not fitted to more recent models. This switch relies on a captive ring movable along a curved path, at both ends of which are pairs of contacts which are touched by the ring when the motor cycle reaches a lean angle of at least 60 from the vertical, causing a circuit to be closed to short circuit the ignition system and hence to stop the motor cycle engine. Both of the aforementioned automatic 'kill switches operate to short circuit the ignition system, which is not a satisfactory means of stopping an engine since overheating and possibly fire may result. Furthermore, both switches restore upon the motor cycle being returned to an upright position, and accordingly igniticn is unwitting restored, which.could result in a hazardous situation. Finally, bot switches, particularly the mercury switch, may be prone to tripping by vibration which is always present in motor cycle operation. It is therefore an object of the present invention to provide an automatic cut-off switch for a motor cycle engine, which switch will operate to stop the engine of a motor cycle in the type of situations described hereinbefore, without the disadvantages of the prior art. Accordingly in one aspect the invention consists in an automatic cut-off switch, for a vehicle propulsion system, including an element responsive to the angular orientation of said vehicle with respect to a reference orientation, characterized in that said switch commences a sequence leading to the cut-off of said propulsion system when said element is indicative of an angular orientation have a predetermined value, and in that means are provided to prevent the operation of said switch to stop the said propulsion system until said element is indicative of said predetermined value of said angular orientation for a predetermined time. In a further aspect, the invention consists in an automatic cut-off switch, wherein said element is a pendulum (18) having an aperture (26,28) therein, said apertures being adapted, when said pendulum is in a position indicative of said predetermined value of said angular orientation, light from a light source (38) may be detected by a light sensor (40) so that light sensor produces an electrical signal, said pendulum operating, in other positions to block light from said light source to said light sensor, preventing said light sensor from producing said electrical signal. The invention may also consist in a switch in accordance with the preceding *paragraph., wherein said switch operates to open the ignition circuit of said propulsion system. C'teT-I The invention may further consist in a switch in accordance with the preceding paragraph, wherein said switch operates to open said ignition circuit, and close a circuit to operate a warning device. In the accompanying drawings: Fig. 1 is a partial side elevation of the pendulum, supporting frame and detection means forming part of a preferred form of the invention; Fig. 2 is an end-view of the pendulum, supporting frame and detection means of Fig. 1; Fig. 3 is a circuit diagram of the switch arrangemen.t of the preferred form of the invention; and Fig. 4 is a diagram of-the forces involved when a motor cycle leans at an angle to the vertical. In Fig. 4, which represents the .state of a motor cycle being ridden through a curve (the normal state) , R is the reaction force experienced by the motor cycle/rider; COG is the centre of gravity of a motor cycle; M is the mass of the motor cycle (and rider) ; V is the linear velocity of the motor cycle; r is the radius of the curve around which the motor cycle is being ridden; and θ is the angle of lean of the motor cycle, in relation to the vertical. While the motor cycle is not out of control, the components of centrifugal and weight forces are such as to maintain the motor cycle in a state of balance. These component forces are shown in broken lines: The following equation can be written: mv g sxn θ = ~- cos θ (1) 2 θ = artan ^ (2) It should be noted that the mass of the motor cycle rider combination plays no part in determining balance. OMPI WIPO When travelling in a straight line, the radius term (r) becomes infinite. Substituting this value into equation (2) we have: 2 θ = artan — 00- θ = artan 0 Λ θ = 0° Neglecting wind effects, and assuming the rider to be mounted symmetrically on the motor cycle, one would expect the angle of lean while travelling in a straight 10 line to be zero, the centrifugal force being zero. Whilst travelling in other than a straight line, θ ≠ 0 because centrifugal force is not zero.- By the use of Pythagoras' theorem, the reaction force R experienced 15 by the motor cycle is given by the formula: R = m /' /αg * 2 ^ ■4+ ■ -* , ((-vT2,))2 (3) and acts from the tyre/pavement interface through the 20 centre of gravity. Note that the centre of gravity of the motor cycle/rider combination can be varied by the rider allowing the weight of his body to be biassed to one or other side of the vehicle. However, such displacement of the centre of gravity is well 25 within the designed critical angle of lean and as such the unit will continue to operate perfectly. A similar situation will result due to a constant side wind causing the need to lean 'into the wind' even while travelling in a straight line. Neglecting the small 30 angles caused by wind or seating asymmetry, any component part of the motor cycle, including either of the prior art automatic cut-off switches, will, when the motor cycle/rider combination is in a state of balance at any value of the angle θ, behave as if the combination ' 35 were travelling in a straight line at an angle of 0°. However, should the motor cycle/rider combination . *° become unbalanced, the motor cycle will lean at an angle to the reference position occupied when the motor cycle is in a state of balance, and it is this angle, or rather a predetermined angle of 'extra' lean which the present invention seeks to define as an 'out of control" or 'fallen' state, and operate to switch off the engine of the motor cycle. " Notwithstanding any other forms that may fall within its scope, one preferred form of the invention will now be described with reference to Figs. 1 to 3 of the accompanying drawings. Fig. 1 is a side elevation of a pendulum arrangement 10, with the 'detecting' part of detection means 36 omitted for clarity. Figs. ' l and 2 show the pendulum in slightly different orientations; in Fig. 1 it is in a 'balance' position, while in Fig. 2 it is shown swung to the extreme left position, with reference to the view of Fig. 1. Referring to both Figures, the pendulum arrangement 10 consists of a pendulum-supporting frame 12, having parallel inverted-ϋ shaped frame members 14,16. The legs of the frame members are secured to a member 20 which, when a motor cycle to which the automatic cut-off switch incorporating the pendulum arrangement 10 is fitted, is in an upright position, is oriented horizontally. Webs 22 (only one of which is shown in Fig. 1) are located beneath the top portions of frame members 14,16. Bearings (only one of which is indicated 44) are set in webs 22, and support an axle 24, on which a thin flattened cylindrical pendulum 18 is mounted for pivotal movement in a plane generally parallel to the planes in which frame members lie, and generally parallel to surface 20. Pins 30,32,34 and 42 are located on both faces of pendulum 18 to limit the swing of the pendulum to approximately 30° each side of the vertical (as illustrated in Fig. 1) . The OMPI Y y -LO pendulum swing is limited by the pins 32,34 or 30,42 striking frame members 14,16. Apertures 26,28 are provided in pendulum 18. Detection means (slotted optical limit switch) 36 is shown as a block secured to surface or member 20. A light emitting diode 38 is located directly opposite an npn phototransistor 40 on either side of pendulum 18. At the maximum swing of pendulum 18 in either direction, aperture 26 or aperture 28 will allow light emitted by the light emitting diode 38 to reach phototransist 40; in effect, the three elements are in a straight line orientation. At other pendulum orientations, the material of the pendulum 18 prevents light from diode 38 reaching phototransistor 40. Turning now to Fig. 3, there is shown a basic circuit of the cut-off switch arrangement of the preferred form of this invention. Detection means (slotted optical limit switch) 36 is shown in broken lines as a block, and has components including the light emitting diode 38, phototransistor 40, and an npn transistor 70. Point 66 of the circuit is intended to be held at a nominal voltage of 12 volts DC. Other components of the circuit includes resistors 46 (3.3 kiloohm) 48 (560ohm) 50(1 kiloohm) and 68 (100 ohm); capacitor 52 (470 microfarad) ; silicon-controlled rectifier (SCR) 56; variable resistor 58 (500 to 1000 ohm); and 100 ohm relay 54, with contacts 60 connected in the ignition circuit 62 and a warning/hazard circuit 64. The arrangement of Figs 1, 2 and 3 operates as follows: When the motor cycle to which the automatic cut-off - switch of this preferred form of the invention is fitted is in a balanced state, no light from light emitting diode 38 reaches phototransistor 40, and the trigger of the SCR 56 is held at zero volts via resistor 50, transistor 70 being essentially open circuited. When the motor cycle destabilizes or falls pendulum 18 will reach one of the extreme positions at which aperture 26 or 28 will allow light to pass from light emitting diode 38 to phototransistor 40, transistor 70 switches to low resistance (closed circuit) mode, and capacitor 52 begins to charge. When the capacitor voltage exceeds the voltage maintained across resistor 68, plus a very small activation voltage for the silicon controlled rectifier 56, the rectifier 56 switches on and remains on, roviding a certain load current is maintained, until the supply current is interrupted. The silicon controlled rectifier switches relay 54 from a position in which it closes circuit 62, and, preferably, to one where it closes circuit 64, thereby activating hazard lighting, a warning sound producing device, or any other _ warning device. The voltage across resistor 68 can be varied in the range 500 to 1000 ohms, thus varying the time for triggering the switch from about 0.5 to about 1.5 seconds. The circuit may be reset after the automatic kill switch has been actuated by interrupting the supply once the motor cycle has been returned to an upright positio This can be effected by turning the ignition switch off, then on again, causing SCR 56 to turn off and relay 54 to again close ignition circuit 62 and open the 'hazard' circuit 64, if one were fitted. In the event that pendulum 18 reaches one of the extreme positions but only remains at that position for a short period of time, capacitor 52 will only charge for the time that light from light emitting diode 38 reaches phototransistor 40, and that will be to a voltage less than that required to switch on the SCR 56; the capacitor will subsequently discharge via resistor 50. Thus, it can be seen that movements of pendulum 18 to one of the two extreme positions does not of itself caused the automatic cut-off switch to operate; calibration of the time the switch will require the pendulum to be at one of the said positions may be determined by a consideration of the effects of vibration, momentary dangerous lean, and other factors. The switch of this embodiment, and this invention could be made as sensitive as desired with respect to the frequency of vibration and the angle of lean. The unit has been designed so that vibration frequency down to about one hertz cannot cause switching to occur. Below this frequency, the amplitude of swing of pendulum 18 is such that apertures 26,28 in the pendulum 18 cannot align with a light emitting diode/light detecting transistor provided in the slotted optical limit switch 36.. Whilst the mass of the motor cycle/rider combination and the pendulum 18 remain constant when the combination j.s negotiating a bend, their apparent weight increases in accordance with equation 3. However, whilst in a state of balance this has no effect on operation of the present invention other than to increase the natural frequency of the pendulum, which has no ill effect on operation of the unit. The elements of the preferred form of the invention, as illustrated in Figs. 1 to 3, are mounted in a strong casing, and the pendulum arrangement 10 may be attached to a surface 20 which is a printed circuit board which is used to house the elements of the circuit shown in Fig. 3. The casing is preferably formed from strong plastics material or metal, and is firmly attached to the motor cycle frame on the centre line thereof, with the circuit board or other surface 20 in a horizontal plane (when the motor cycle is standing upright in a vertical orientation) with the pendulum 18 able to move in a plane at right angles to the plane through the centre line of the motor cycle, a vertical plane when the motor cycle is in an upright position. It would be possible to provide self-latching of the set of relay contacts 60 associated with circuit 64, or an Off setting. However, this arrangement is not generally regarded as satisfactory, since vibration could conceivably cause contacts to touch, whereupon the relay would operate, causing loss of ignition. Magnetic latching of the relay could be employed, but resetting of the relay would not be as simple as in the arrangement (using the SCR 56) described hereinbefore. The use of an SCR with a relay, or a magnetic self-latching relay, is inherently safe because while shock and/or vibration may cause momentary loss of ignition, merely causing a 'miss' in the engine, the automatic cut-off switch would not operate. The" type of circuit of Fig. 3 could be used with a different 'lean detection' mechanism in the box 36, for example a mercury switch (which, as we have discussed hereinbefore, is per se not a satisfactory automatic cut-off switch) in which a drop of mercury in a tube will, at each of two ^ extreme positions, touch two contacts and close an electrical circuit, operating the switch with a modified Fig. 3 circuit. Alternatively magnetic reed relay switch could be used, or even the prior art 'ring' arrangement discussed hereinbefore; in each case, a signal from such a device would be used to switch a relay, which in turn switches an ignition circuit. In the design of the automatic kill switch of this invention, safety was of primary concern. As such, a fail safe philosophy was adopted which means that in the event of a component in the unit failing, the device wherever possible will become inoperative, rather than operate incorrectly and thus reduce the safety level below that of motor cycle riding without an automatic kill switch. OMPI

Claims: 1. An automatic cut-off switch for a vehicle propulsion system, including an element responsive to the angular orientation of said vehicle with respect to a reference orientation, characterized in that said switch commences a sequence leading to the cut-off of said propulsion system when said element is indicative of an angular orientation have a predetermined value, and in that means are provided to prevent the operation of said switch to stop the said propulsion system until said element is indicative of said predetermined value of said angular orientation for a predetermined time. 2. An automatic cut-off switch according to claim 1, wherein an electrical signal is produced when said element has an angular orientation of said predetermined value, the presence of said electrical signal commencing said sequence of said switch. 3. An automatic cut-off switch according to claim 1, wherein said element is a pendulum (18) having an aperture (26,28) therein, said apertures being adapted, when said pendulum is in a position indicative of said predetermined value of said angular orientation, light from a light source (38) may be detected by a light sensor (40) so that light sensor produces an electrical signal, said pendulum operating, in other positions to block light from said light source to said light sensor, preventing said light sensor from producing said electrical signal. 4. An automatic cut-off switch according to claim 2 or 3, wherein while said electrical signal is present, a capacitor (52) charges until it reaches a predetermined voltage, at which a silicon-controlled rectifier (56) will switch on, activating a relay (54) to open-circuit the ignition system (62) of said propulsion system, and wherein if said electrical signal ceases to be present before said predetermined voltage is reached, said capacitor will discharge to earth. 5. An automatic cut-off switch according to claim 4, wherein said predetermined time may be set by adjusting a variable resistor (58) . 6. An automatic cut-off switch according to any one of claims 3 to 5, wherein said pendulum (18) is suspended for movement in a plane at right angles to the vertical, when said vehicle is upright on a horizontal surface, and- to the instantaneous direction of travel. 7. An automatic cut-off switch according to claim 6, wherein said pendulum (18) is a flattened cylinder suspended by a frame (12) to move in said plane, which is the plane parallel to the circular surfaces of said pendulum, there being two said apertures (26,28) each aperture representing an angular extreme from a mid point, the pendulum being provided with pins (30, 32,34,42) to prevent, by co-operation with frame members (14,16) forming said frame, said pendulum from moving past said two extremes, said apertures being in register with a light-emitting diode (38) and a phototransistor (40) at said two extremes, thus allowing light from said diode to reach said phototransistor, producing an electrical signal from said phototransistor. 8. An automatic cut-off switch according to any one of claims 4 to 7, wherein said relay (54) operates, when cutting off the ignition circuit (62) of said propulsion system, to close a visual or audible hazard circuit (64) . 9. An automatic cut-off switch according to any preceding claim, further including means to interrupt the power supply to said switch to reset said switch so that said propulsion system may be re-started. 10. An automatic cut-off switch according to any preceding claim, wherein said vehicle is a two-wheeled motor cycle. -- • s^-Tt

Inventors: VAN OOSTERWIJCK LUKE ALOYSIUS, VAN OOSTERWIJCK, LUKE, ALOYSIUS, BLASIUS
Applicants: OOSTERWIJCK LUKE ALOYSIUS BLAS, VAN OOSTERWIJCK, LUKE, ALOYSIUS, BLASIUS
Application year: 1983
Main classification: F02P11
IPC codes: F02P11