WO1997010686A1

WO1997010686A1 - Electrical power distribution switching means

Info

Publication number: WO1997010686A1
Application number: PCT/NZ1996/000098
Authority: WO
Inventors: Ashby Robert Howitt; George Matehe Tuau
Original assignee: Ashby Robert Howitt; George Matehe Tuau
Priority date: 1995-09-15
Filing date: 1996-09-13
Publication date: 1997-03-20
Also published as: AU6892096A

Abstract

A device (2) which will automatically switch electrical power to an electrically powered accessory (8). The device includes a light sensor means (3) which will detect the level of ambient light and generate a signal and a detecting means (1) to detect the presence of electrical power in an electrical indicator circuit. When the level of ambient light is below a predetermined level and electrical power is present in the electrical indicator circuit, the device will switch electrical power to said accessory. The light sensor means generates a signal which is processed by a transient conditions filter (5) to filter temporary and/or minor variations in the level of ambient light.

Description

Electrical Power Distribution Switching Means

Technical Field

This invention relates to a device for automatically switching electrical power to

selected electrical power consuming devices.

In particular the invention relates to a device which when certain conditions are encountered, can interrupt the delivery of or initiate the delivery of electrical power to electrical accessories powered by a battery type of electrical storage system.

In an even more specific application, the invention relates to a means capable of automatically interrupting the delivery of or initiate the delivery of electrical power to

electrical accessories which are powered by an electrical storage battery according to whether the level of ambient light is above or below a predetermined threshold.

Background to the Invention

Motor vehicles generally have an electrical storage device such as a lead acid battery which is maintained in a charged state by electrical generating means such as an alternator or generator which is driven by the engine which otherwise provides the motive power for the vehicle. A continuing problem with motor vehicles is that the headlights or other electrical power consuming apparatus can be left in a turned on state while the vehicle engine is not running. In this situation no power is being generated nor delivered to the battery and in certain circumstances, this can result in a total or substantial discharge of the battery. Consequently when the engine of the vehicle is to be restarted there is either insufficient or no electrical capacity to enable the electrical starter motor of the motor vehicle to operate.

Various means of overcoming this disadvantage have been proposed in the past, one such means consisted in constructing the storage battery with compartments so that will one compartment will retain its charge even though another compartment might be in a discharged state. This results in sufficient electrical power being available to restart the engine of the vehicle. The disadvantage with such a known type of battery is that it is comparatively expensive and its storage capacity can be less than an equivalent sized single compartment battery. In addition, the operation of such a battery requires comparatively complicated electronic equipment in the form of a motion detector that is able to detect when the car is in motion and thus allow the vehicle to utilise all of the available storage power of the battery. When the vehicle is stationary, one compartment of the battery only is available for use, thus saving the other compartment in the event of the excessive electrical energy being drained from the first compartment of the battery.

Another disadvantage with the known multiple compartment type of battery is that it is generally unusable in moored boats, because ofthe movement imparted to the boat by the water. A yet further disadvantage is that if the vehicle in which the battery is installed is subject to any excessive movement which can happen, for instance, during a gust of wind, then this can result in the second compartment being electrically connected to the first compartment. Such known multiple compartment types of batteries have further disadvantages in that they are generally available in one specific size only and because of their complexity they are expensive in comparison with a standard type of battery.

Car manufacturers have endeavoured to alleviate the problem of leaving the headlights and other electrical power consuming devices turned on when the vehicle engine is not operating, by incorporating various forms of visible and/or audible alarms so that when the ignition key is in the off position and the lights are on, then in certain conditions, the alarm is activated. This form of warning is only partly successful in that it requires the person to take notice ofthe warning and to act by physically actuating the switch which will interrupt the electrical circuit. In addition, it is possible for a person to either ignore the warning or not to see or hear the warning with sometimes highly adverse results.

Another method of partially alleviating the problem consists in installing a switching mechanism with the headlights and optionally with other circuits so that when the ignition switch is turned to the off position, then the headlights and/or other equipment are turned off. However because of the comparatively small size of electrical storage batteries now used in motor vehicles even side lights and sometimes interior lights, if left turned on can result in a total or substantial discharge of the storage battery within a comparatively short

time.

Another difficulty with motor vehicles is that it is possible to inadvertently drive a motor vehicle at night without the headlights being turned on. This is a well recognised dangerous situation but in certain circumstances, it might not be recognised by the driver of the vehicle that the headlights are not illuminated.

Prior Art

New Zealand Patent Specification 120066 to Ford Motor Company of Canada

Limited discloses a thermal time delay switch which is utilised to maintain the motor vehicle head lamps in a lit condition for a predetermined period after the circuit has been broken by the normal switching means. Such a method however does not solve the problem of the headlights or the other lights being left on when the vehicle is parked or unattended.

Object of the Invention

It is an object of this invention to provide an improved means of automatically controlling the supply of electrical energy from a storage battery to selected accessories dependent upon the fulfilment of predetermined conditions.

It is an additional and ancillary object of this invention to provide a means for automatically connecting or disconnecting electrical power to the headlights and/or other accessories of a motor vehicle depending upon a predetermined level of ambient light and depending upon the status of a selected part of the electrical circuit of the vehicle.

Disclosure of the Invention

Accordingly the invention comprises an electrical power switching means to connect and/or disconnect electrical power from a rechargeable electrical storage system to an electrically powered accessory, said switching means comprising; detecting means to detect the presence of electrical power in an indicator electrical circuit, and

at least one light sensor means to detect the level of ambient light,

the construction and arrangement being that the electrical power switching means will connect and maintain electrical power to the said electrically powered accessory when: (a) the detecting means detects the presence of electrical power in said indicator circuit, and

(b) the level of ambient light is less than a predetermined threshold.

Preferably the system includes a transient conditions filter connected to the means to generate an electrical signal.

In a further aspect, the invention comprises a method of controlling the distribution of electrical power to an electrically powered accessory comprising a system including: means to detect the presence of electrical power in an indicator electrical circuit; means to detect the level of ambient light and to generate an electrical signal dependent upon the level of ambient light; a transient conditions filter connected to said means to generate an electrical signal;

wherein the system will connect electrical power to said electrically powered accessory when electrical power is detected in said indicator electrical circuit and when the ambient light detecting means generates an electrical signal above a pre set level, and

wherein said connection or disconnection of electrical power is delayed by the transient conditions filter for a predetermined time after a change in the output of the means to detect the level of ambient light such that said connection or disconnection is dependent on a steady state change in the level of ambient light.

Preferably the system includes a power up delay to delay the connection of electrical power to said electrically powered accessories after electrical power has initially been detected in said indicator electrical circuit.

Preferably the power up delay circuit is connected to the output of said transient conditions filter.

Preferably the system includes the time delay to maintain the steady state of the switching means for a period following a change in the level of ambient light above or below a predetermined threshold comprises a hysteresis triggering device.

Preferably the said indicator electrical circuit is the ignition circuit of a motor vehicle.

Preferably the system includes means to enable the threshold ofthe level of ambient light to be adjusted.

Preferably a connection or disconnection signal from said light sensor means is delayed by said transient conditions filter for a predetermined time such that the said connection or disconnection is dependent upon a steady state change in the level of ambient light.

Brief Description of the Drawings

One preferred form of the invention will now be described with the aid of the accompanying drawing in which:

Figure 1 is a block diagram of a preferred embodiment automated electrical switching system; and

Figure 2 is a circuit diagram of a battery saving device and automated lighting

system.

Referring to Figure 1, a preferred form automated switching system comprises an indicator electrical circuit 1, an external circuit 8, and a switching device 2 comprising a light sensor mechanism 3, a hysteresis triggering device 4, a transient conditions filter circuit 5, a power up delay circuit 6, and an external device relay circuit 7.

The system controls the external circuit 8 according to the ambient level of light and the availability of electrical energy. This is particularly useful in vehicle lighting systems which are required to provide artificial lighting during natural darkness and which rely on electrical storage devices such as batteries to do this.

The indicator electrical circuit 1 detects the availability of electrical power, for example it may detect whether the generator of the motor vehicle is charging the battery or whether the ignition system of a motor vehicle powered by a petrol engine has been energised by manual operation of the ignition key.

The availability of electrical power as determined by the indicator electrical circuit

1 enables the light sensor circuit 3 which converts the ambient lighting level into an electrical signal or voltage level. The sensitivity of the sensor circuit 3 to lighting levels can be adjusted to increase or decrease the voltage level for a given lighting level as desired. This can be used to adjust the threshold lighting levels at which the external circuit 8 is switched on or off. Preferably the sensor circuit 3 utilises a light dependent resistor.

The light sensor circuit 3 is connected to a hysteresis triggering device 4 such as a Schmidt trigger to generate a steady bistable output (light or dark) from the signal from the sensor circuit 3. The hysteresis triggering device 4 incorporates different high and low input thresholds at which it switches between light and dark output signals. This avoids a rapidly changing output signal when the signal from the sensor circuit 3 is slowly varying near a particular threshold. For example when the low level or dark input threshold is reached, the triggering device 4 switches to a dark output and the signal level of the sensor circuit 3 has to increase above this to a high or light input threshold before the triggering device switches back to a light output.

The triggering device 4 is connected to a transient conditions filter 5 which filters out transient changes in the output signal of the triggering device 4. The purpose of the filter 5 is to avoid frequent on/off switching of the external circuit 8 due to transient lighting conditions for example, the light of the headlights of an oncoming motor vehicle in ambient darkness. The delay circuit 5 enables the system to discriminate between steady state and temporary increases or decreases in the level of ambient light. This is particularly important in applications of the system to motor vehicles where the likelihood of temporary changes in lighting levels is increased by the mobility of the vehicle.

The transient conditions filter 5 is connected to the external device relay circuit 7 either directly or via a power up delay circuit 6. The external device relay circuit 7 switches the external device 8 according to the steady state ambient level of light and the availability of electrical power. For example the external device 8 could be the headlight circuit of a motor vehicle which is automatically switched on during low steady state levels of ambient light and battery charging or ignition on conditions, and is automatically switched off either when the steady state ambient lighting level rises above a preset level, or when the battery is no longer being charged or the ignition circuit is off as indicated by the indicator electrical circuit 1.

A power up delay circuit 6 can be included in the switching device 2 to delay a dark or external device on signal if the system or the device 2 has just been powered up. For example if the ignition switch of the motor vehicle has just been switched on in ambient darkness, the power up delay circuit 6 will delay the signal to switch on the headlights. This will minimise the drain on the storage battery during start up of the vehicle engine.

An override switch (not shown) may be included in the external device 8 to override the automated on/off signals from the switching device 2. For example an automated headlight system for a motor vehicle may be overridden such that the headlights may be switched on during relatively high levels of ambient light or when the battery is not being charged or the ignition is off. An alarm system (not shown) may be fitted to warn the operator of the motor vehicle that the manual override switch is on while the battery is not being charged.

Figure 2 shows the preferred embodiment system applied to a petrol engine motor vehicle as a battery saving device and automated lighting system. Circuit elements equivalent to the elements in Figure 1 are numbered the same. The indicator electrical circuit 1 is preferably the ignition circuit of a motor vehicle.

Preferably the system also includes a power regulator and protection circuit 9.

The light sensor circuit 3 includes a light dependent resistor and a variable resistor in a voltage divider circuit. The signal output or voltage level for a given level of ambient light can be varied by adjusting the variable resistor. The hysteresis triggering device 4 is a joined input NAND gate with hysteresis or different high and low input level thresholds. The device 4 generates either a lights off or lights on signal or state corresponding to a high (light) or low (dark) input level respectively.

The system filters out unwanted transient lighting conditions imposed on the steady state light levels using a lights on and lights off signal delay circuit 5. The circuit 5 transmits signals only if they are maintained for a predetermined length of time, corresponding to a change in the steady state rather than transient lighting levels.

The lights on and lights off delay circuitry 5 component values can be adjusted to produce the desired lights off and lights on delays. Similarly the power up delay circuitry 6 component values can be adjusted to provide a suitable power up delay as previously described.

The external device relay circuitry 7 switches the main and side lights of the motor vehicle on when enabled by the supply of power from the battery (when the ignition is switched on), and by low steady state levels of ambient lighting. The main and side lights of the motor vehicle are switched off if the steady state level of ambient lighting rises above a present threshold, or power is removed from the system by the switching off of the ignition switch.

Means can also be provided, such as a light emitting diode to provide visual indication of the status of the unit.

The unit is preferably connected directly to the electrical circuit ofthe motor vehicle and will bypass the usual main lighting switch to send power automatically to the side lights and the headlights only when the ignition switch is turned on. To obtain this, the unit is wired to the vehicle electrical system so that power will be fed to the side lights and head lights only when the ignition switch is turned on.

Typically the time delay from when the light sensor detects a low ambient light level until power is applied to the vehicle accessories can be of the order of five seconds, while the delay after the light sensor detects levels above the predetermined level is in the order of 12 seconds but this can vary as required depending upon the particular circumstances.

In a modification the system can be designed so that the circuit from the battery to the head lamps and or other accessories will be broken only upon the combination of certain events such as the non-generation of electrical power and when the ignition switch is turned off thereby ensuring the head lights will remain illuminated even during an engine stall situation.

In a still further modification, the system can include a by-pass in conjunction with the switching means so that when the relay is in the turned off condition, electrical power will be connected to the accessories, which may be for instance an electrical clock, burglar alarm and the like. This can be arranged as a separate by-pass or the switch mechanism can be arranged to allow such an occurrence.

While the present invention is particularly concerned with the control of electric power to the head lights of a motor vehicle, it can also be utilised to control power to other accessories of a motor vehicle or to accessories or lighting of any device whereby the electrical storage battery is charged by an electrical generating device which operates only when the engine is running. Situations where such a device will be of particular assistance is for instance in boats or in any mobile or fixed situation where it is undesirable for the electrical storage system to become completely discharged.

In a preferred form of this aspect of the invention, at least one light sensor is mounted on or in the motor vehicle so the or each sensor will sample the ambient light. Means can also be provided to override the circuitry and to modify or adjust the sensitivity of the operation of the circuitry to suit particular circumstances as required.

The foregoing describes preferred forms of the invention and having read the description and understood the principles and precepts of the invention, it will be apparent to those skilled in the art that modifications and amendments can be made which would still fulfil the general concepts as herein disclosed. All such modifications and amendments are intended to be included in the scope of this invention as defined in the appended claims.

Claims

1. An electrical power switching means to connect and/or disconnect electrical power from a rechargeable electrical storage system to an electrically powered accessory, said switching means comprising; detecting means to detect the presence of electrical power in an indicator electrical circuit, and

at least one light sensor means to detect the level of ambient light,

the construction and arrangement being that the electrical power switching means will connect and maintain electrical power to the said electrically powered accessory when: (a) the detecting means detects the presence of electrical power in said indicator circuit, and (b) the level of ambient light is less than a predetermined threshold.

2. The electrical power switching means as claimed in claim 1 , further comprising a transient conditions filter.

3. The electrical power switching means as claimed in claim 1, further comprising a power up delay circuit.

4. The electrical power sitching means as claimed in claim 1, wherein the light sensor means comprises a light dependent resistor, a variable resistor and a hysteresis triggering device.

5. A method of controlling the distribution of electrical power to an electrically powered accessory comprising a system including: means to detect the presence of electrical power in an indicator electrical circuit; means to detect the level of ambient light and to generate an electrical signal dependent upon the level of ambient light; a transient conditions filter connected to said means to generate an electrical signal;

6. The method as claimed in claim 5, including a power up delay to delay the connection of electrical power to said electrically powered accessories after electrical power has initially been detected in said indicator electrical circuit.

7. The method as claimed in claim 5, wherein the power up delay circuit is connected to the output of said transient conditions filter.

8. The method as claimed in claim 5, wherein the means to detect the level of ambient light includes a light dependent resistor, a variable resistor and a hysteresis triggering device.

9. The electrical power switching means as claimed in claim 1, wherein the said indicator electrical circuit is the ignition circuit of a motor vehicle.

10. The electrical power switching means as claimed in claim 1, including means to enable the threshold of the level of ambient light to be adjusted.

1 1. The electrical power switching means as claimed in claim 2, wherein a connection or disconnection signal from said light sensor means is delayed by said transient conditions filter for a predetermined time such that the said connection or disconnection is dependent upon a steady state change in the level of ambient light.