GB2372383A

GB2372383A - Anti-restart keyswitch assembly

Info

Publication number: GB2372383A
Application number: GB0124241A
Authority: GB
Inventors: Robert Q Elliott
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2000-11-16
Filing date: 2001-10-10
Publication date: 2002-08-21
Also published as: GB0124241D0

Abstract

An anti-restart keyswitch assembly (101) for use with a starter assembly (118) coupled with an engine (119), the engine (119) having at least one component adapted for rotational movement thereto. Provided is a housing and a body disposed at least partly within the housing and moveable relative to the housing to at least a starter activation position (111). An anti-restart device (114) operatively couples the keyswitch assembly (101) with the engine (119) and is adapted to deactivate the starter assembly (118) upon receiving a pre-selected magnitude of rotation of the component.

Description

Description ANTI-RESTART KEYSWITCH ASSEMBLY Technical Field This invention relates to a anti-restart keyswitch assembly and more particularly to such a anti-restart keyswitch assembly in which an antirestart device may be incorporated with a keyswitch assembly.

Background Art In the operation of modern day vehicles, it is common to start the vehicles using some type of an ignition switch or key operated switch which is operatively coupled to the vehicle's starter. Placing the keyswitch in the"start"condition causes current to flow from the vehicle's power supply, typically a battery, to the starter, thereby activating the starter. Upon such an occurrence, the starter provides translational and rotational movement to the starter solenoid pinion gear which meshingly engages a ring gear located on the engine's crankshaft. The vehicle operator maintains the keyswitch in the start condition until such time as the engine is capable of operating under its own power. At this time, the operator senses, typically by hearing, that the engine has started and releases his or her hold on the key causing the keyswitch to automatically be positioned, typically via a spring, in a"run"condition.

Advances made in engine vibration reduction, knock control, and exhaust systems have given rise to quieter vehicles which may not provide to the operator an discernable audible signal that the engine has started. As a result, inadvertent starts are often caused by the vehicle operators if they are unaware that the vehicle has started. Attempted restarts results in grinding of the pinion gear with the ring gear which not only causes an alarming noise, but also may result in damage to the starter, the ring gear, or both. It has been known to use a mechanical device in conjunction with the ignition switch, commonly referred to as a"cat's paw", which prevents subsequent re-start attempts by the operator until the operator first places the ignition switch in the"off" condition. Though somewhat successful, the mechanical nature of such devices may make them prone to breakage which, upon such an occurrence, may disable the vehicle and prevent starting altogether.

One prior art attempt to eliminate the aforementioned problem can be found in U. S. Patent No.

6,024, 065 issued on 15 February 2000 to Robert E.

Hojna. In this design, the vehicles Electronic Control Unit (ECU) is programmed to de-activate the starter upon receiving a signal indicative of the revolutions per minute (RPM) of the vehicle. While this design may be suitable for its intended purpose, it can only be practiced with vehicles that are equipped with an ECU.

Another prior art attempt can be found in U. S. Patent No. 5,936, 316 issued on 10 August 1999 to James S. Jurkiewicz et al. which discloses an ignition switch having a combined run and start position. In this design, the engine controller is programmed to also receive input indicative of the engine RPM and deactivate the starter when the engine RPM reaches a pre-determined speed. Although this design may also be suitable for its respective intended purpose, it can only be practiced with vehicles having an engine controller.

The present invention is directed to overcoming one or more of the problems as set forth above.

Disclosure of the Invention Various aspects of the invention are defined in the independent claims. Some preferred features are defined in the dependent claims.

In one aspect of the present invention, an anti-restart keyswitch assembly for use with a starter assembly coupled with an engine having at least one component adapted for rotational movement thereto is provided. The anti-restart keyswitch assembly includes a housing and a body disposed within the housing and moveable relative to the housing to at least a starter activation position. An anti-restart device operatively couples the keyswitch assembly with the engine and is adapted to deactivate the starter assembly upon receiving a pre-selected magnitude of the rotation of the component.

In another aspect of the present invention, a method for preventing re-start attempts of a running engine which is coupled to a starter is provided. The method includes the steps of (1) measuring the rotational speed of an engine, (2) converting the rotational speed of the engine to an output signal, (3) comparing the output signal to a reference signal, and (3) deactivating the starter when the output signal reaches a pre-selected magnitude.

Brief Description of the Drawings Fig. 1 is a diagram of an ignition circuit that embodies the principles of the present invention.

Fig. 2 is a diagrammatic elevation view, in cross-section, of a keyswitch assembly for use in the ignition circuit of Fig. 1.

Fig. 3 is a circuit diagram illustrating a preferred embodiment of the anti-restart device of the present invention.

Fig. 4 is a flowchart of a method of prohibiting the re-start of a running engine according to the present invention.

Best Mode for Carrying Out the Invention Referring to the drawings, a simplified diagram of an ignition circuit incorporating the principles of the present invention is shown generally at 100. Shown is keyswitch assembly 101 connected to a power source such as a battery 102 by a suitable electric lead 105. The keyswitch assembly 101 is preferably a multi-positional keyswitch operable between, respectively, and"Off"state 106, an "Accessory"state (ACC) 109, a"Run"state 110, and a "Start"state 111. Preferably integrally incorporated as a part of the keyswitch assembly 101 is the antirestart device 114 of the present invention operatively coupled, by suitable electric leads 115, with a starter 118. The starter 118 may be of a conventional type having a solenoid (not shown) engagable with a crankshaft ring gear (not shown) of an engine 119. An alternator 120 is typically mechanically coupled with the engine 119 and includes a rotatable armature (not shown) for generating an electric current used, for example, to charge battery 102 when the engine 119 is operating.

The anti-restart device 114 is also preferably operatively coupled, by suitable electrical leads 122, to the tachometer circuit 123. The tachometer circuit 123 may also be of a conventional type which is operatively coupled to an alternator 120, via a suitable lead 125, in order to convert either the alternator voltage, or frequency of rotation of the alternator armature (not shown), to an analog or digital user-readable representation of the rotational speed, or revolutions per minute (RPM), of the crankshaft.

With reference to Fig. 2, an exemplary keyswitch assembly 101 is shown. The keyswitch assembly 101 includes a housing 202 having an aperture 203 for either fully or partially receiving a body 204 rotatably moveable therein to any one of the four aforementioned"Off","Accessory","Run", or"Start" states. As shown, the body 204 is preferably physically separated from the housing 202 and is preferably provided at end 207 with a magnetic device 208. At least one corresponding magnetic sensing device 211, preferably a Hall effect device, is provided on the housing-attached circuit board 212.

Such magnetic sensing devices 211 should be readily familiar to those skilled in such art and will not be elaborated upon in any detail greater than needed to fully describe the present invention. Suffice to say, the magnetic sensing devices 211 of the type described herein are sensitive to the proximity of magnetic fields and generate a current when the magnetic field reaches a given strength. Thus, the magnetic sensing devices 211 function as switches which pass current when the strength of the magnetic field reaches a predetermined level.

As should be appreciated, the keyswitch assembly 101 preferably includes the anti-restart device 114. As shown, the anti-restart device 114 is preferably attached to the housing 202, and more preferably, incorporated into an existing circuit board 212, thereby conveniently providing the keyswitch assembly 101 and anti-restart device 114 as a single unit. As should be appreciated by those skilled in such art, the aforementioned union of the keyswitch assembly 101 and anti-restart device 114 advantageously avoids the necessity of installing a separate anti-restart module in the ignition circuit 100. However, as should become apparent as this disclosure progresses, the anti-restart device 114 of the present invention can also be installed in the ignition circuit 100 in a location remote from the keyswitch assembly 101, if desired, Referring now to Fig. 3, a schematic view of a particular embodiment of the present invention for the keyswitch assembly 101 is shown. The keyswitch assembly 101 includes a start circuit shown generally at 301, and a run circuit shown generally at 302. For purposes of illustration and not limitation, the keyswitch assembly 101 is shown utilizing two Hall effect sensor-type magnetic sensing devices denoted 211'and 211"incorporated into, respectively, the run and start circuits 301,302.

Rotating the body 204 in such manner as to place the magnetic device 208 in the position denoted 208'causes current to flow through sensor 211'which energizes coil 306. As should be apparent, when energized, coil 306 produces a magnetic field which biases a switch 307 into a closed condition denoted 307', thereby closing the run circuit 302. Similarly, rotation of the body 204 in such manner as to place the magnetic device 208 in the position denoted 208" causes current to flow through sensor 211"which energizes coil 310, biases switch 311 into a closed position denoted 311', and passes current to the anti restart device 114 of the present invention which will be described immediately hereinafter.

The anti-restart device 114 includes a conversion device 314 adapted to convert an alternator output signal, preferably comprising the frequency of the armature rotation denoted herein by Altout, to an output voltage signal denoted Sout-The conversion device 314 preferably comprises a frequency-to-voltage converter, and more preferably a series 289 integrated chip (IC) commercially available from Teleflex Electrical (Sarasota, Florida). Advantageously, and as shown, the aforementioned alternator output signal Altout preferably is taken directly from the tachometer leads 125, thereby eliminating the necessity to run separate leads to the location of the alternator 120.

Alternatively, either a direct connection of the antirestart device 114 to the alternator 120 or a means such as conventional motion detecting devices for monitoring the rotational speed of an engine component may be utilized, if desired.

The output voltage signal Sout is transmitted to a comparison device 319 which compares the output voltage signal Sout to a reference signal denoted Sref.

The comparison device 319 preferably comprises a comparator, and more preferably a series 2903 IC of the type commercially available from the National Semiconductor Corporation (Santa Clara, California).

It is preferred that the reference signal Sref comprise a voltage differential supplied by at least one resistor 320 suitably selected to cause the comparison device 319 to cease passing of current, in a conventional manner, when the output voltage signal Sout meets or exceeds the voltage differential from the resistor 320.

As should be appreciated, the resistor 320 is selectable to provide a voltage differential corresponding to a specific RPM of the engine crankshaft, preferably approximately 500 RPM, as embodied by alternator output signal Altout. It should be understood that although the preferred resistor 320 will correspond to the aforementioned preferred engine speed of 500 RPM, a resistor or resistors with different voltage differential characteristics may be chosen depending upon the specific engine starting characteristics.

Thus, it can be seen that the above described anti-restart device 114 operates as an electric switch which de-activates the starter 118 when the engine revolutions per minute (RPM) meets or exceeds a pre-selected value. More specifically, the anti-restart device 114 closes start circuit 301 when the keyswitch assembly 101 is placed in the"Start" state 111 and, assuming the engine 119 has not already been started and is running at 500 RPM, supplies current to the starter 118. The start circuit 301 remains closed until the engine 119 reaches 500 RPM, at which time the anti-restart device 114 is triggered to prevent current flow through the start circuit 301, thereby de-activating the starter 118. As should be appreciated, any subsequent attempts to re-activate the starter 118 will not be successful while the engine 119 is running.

Referring now to Fig. 4, a flow chart of a method of preventing re-start attempts of a running engine 119 utilizing the anti-restart device 114 of the present invention is shown. The methodology begins at bubble 400 with the keyswitch assembly 101 being placed in the"Start"state 111. In block 402, the methodology converts the alternator output signal Atout, which is indicative of the RPM of the engine 119, to an output voltage signal Sout-Continuing on to block 405, the comparison device 319 compares the output voltage signal Bout to a reference voltage signal Sref indicative of a specific engine RPM. With reference to decision block 406, if signal Bout equals or exceeds signal Sref, current to the starter 118 is discontinued, thereby terminating the starter actuating procedure as illustrated by block 407.

However, if signal Bout is less than Bref, the procedure reverts to block 402 and repeats as needed until signal Bout equals or exceeds signal Sref.

Industrial Applicability With reference to the drawings and in operation, the keyswitch assembly 101 of the present invention preferably and advantageously combines the functionality of an ignition switch or keyswitch assembly 101 with an anti-restart device 114, thereby eliminating the need to either install a separate anti-restart-type module in the ignition circuit 100 or re-configure the existing vehicle electronics to provide this capability. As should be appreciated, the keyswitch assembly 101 prohibits successive potentially vehicle-damaging attempts to re-start the engine 119 unless the keyswitch assembly 101 is first placed in the"Off"state 106.

As shown best in Figs. 3 and 4, the conversion device 314 converts frequency signals generated from the rotating armature of the alternator 120 into an output voltage signal Soutthat is indicative of the RPM of the vehicles crankshaft.

Advantageously, the aforementioned frequency signals may be taken directly from the tachometer lead 125.

The comparison device 319 receives the signal S,, ut and compares it to a reference signal Sref which preferably comprises a voltage differential provided by resistor 320 suitably selected to provide a voltage differential indicative of a pre-selected engine RPM.

The comparison device 319 will continue to compare the signal Soutto Sref until such time as gout equals or exceeds Brei. Upon this occurrence, the comparison device 319 will open the start circuit 301 thereby deactivating the starter 118. As should also be appreciated, any subsequent attempts to re-activate the starter 118 will not be successful unless the keyswitch assembly 101 is first placed in the"Off" state 106.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure, and the appended claims.

Claims

1. An anti-restart keyswitch assembly for use with a starter circuit having a starter assembly, an alternator adapted to produce a alternator signal, and a tachometer circuit, comprising: a keyswitch assembly including (i) a housing, and (ii) a body disposed at least partly within said housing and moveable relative to said housing to at least a starter activation position; and an anti-restart device operatively coupling said keyswitch assembly with the alternator and adapted to deactivate the starter assembly upon receiving a pre-selected magnitude of the alternator signal.

2. The anti-restart keyswitch assembly as set forth in claim 1 wherein said keyswitch assembly includes said anti-restart device.

3. The anti-restart keyswitch assembly as set forth in claim 2 wherein said anti-restart device is attached to said housing.

4. The anti-restart keyswitch assembly as set forth in claim 1 wherein said anti-restart device comprises a switch device.

5. The anti-restart keyswitch assembly as set forth in claim 3 wherein said anti-restart device includes : a conversion device adapted to convert the alternator signal to an output signal; and a comparison device for comparing a reference signal with said output signal.

6. The anti-restart keyswitch assembly as set forth in claim 5 wherein: said conversion device is a frequency-tovoltage converter; and said comparison device is a voltage comparator.

7. The anti-restart keyswitch assembly as set forth in claim 5 wherein said reference signal is a voltage differential.

8. The anti-restart keyswitch assembly as set forth in claim 7 wherein said switch device includes at least one resistor adapted for providing said voltage differential.

9. The anti-restart keyswitch assembly as set forth in claim 1 wherein said body and said housing are substantially physically separated.

10. The anti-restart keyswitch assembly as set forth in claim 1 wherein said keyswitch assembly includes a magnetic sensing device for activating the starter.

11. The keyswitch assembly as set forth in claim 10 wherein said magnetic sensing device comprises a hall effect switch.

12. The keyswitch assembly as set forth in any one of the preceding claims wherein said alternator signal is taken from said tachometer circuit.

13. An anti-restart keyswitch assembly, comprising: a starter circuit having an alternator adapted to produce an alternator signal, a starter assembly, and a tachometer circuit coupled to said alternator; an engine coupled to said starter assembly; a keyswitch assembly electrically coupled with said starter circuit and having (i) a housing, (ii) a body disposed within said housing and moveable relative to said housing to at least a starter activation position, and (iii) an anti-restart device operatively coupling said keyswitch assembly with the tachometer circuit and adapted to deactivate the starter assembly upon receiving a pre-selected magnitude of said alternator signal; and said anti-restart device includes (i) a conversion device adapted to convert said alternator signal to an output signal, (ii) a comparison device for comparing a reference signal with said output signal, and (iii) at least one resistor adapted to provide said reference signal.

14. The anti-restart keyswitch assembly as set forth in claim 13 wherein : said conversion device is a frequency-tovoltage converter; and said comparison device is a voltage comparator.

15. The anti-restart keyswitch assembly as set forth in claim 13 wherein said reference signal is a voltage differential.

16. An anti-restart keyswitch assembly for use with a starter assembly coupled with an engine, said engine having at least one component adapted for rotational movement thereto, comprising: a housing, a body disposed at least partly within said housing and moveable relative to said housing to at least a starter activation position, and an anti-restart device operatively coupling said keyswitch assembly with the engine and adapted to deactivate the starter assembly upon receiving a preselected magnitude of said rotation of said component.

17. The anti-restart keyswitch assembly as set forth in claim 16 wherein said anti-restart device comprises a switch device.

18. The anti-restart keyswitch assembly as set forth in claim 16 wherein said anti-restart device includes: a conversion device adapted to convert said magnitude of said rotations to an output signal; and a comparison device for comparing a reference signal with said output signal.

19. The anti-restart keyswitch assembly as set forth in claim 18 wherein: said conversion device is a frequency-tovoltage converter; and said comparison device is a voltage comparator.

20. The anti-restart keyswitch assembly as set forth in claim 18 wherein said reference signal is a voltage differential.

21. The anti-restart keyswitch assembly as set forth in claim 20 wherein said anti-restart device includes at least one resistor adapted for providing said voltage differential.

22. The anti-restart keyswitch assembly as set forth in claim 16 wherein said body and said housing are substantially physically separated.

23. The anti-restart keyswitch assembly as set forth in claim 16 wherein said keyswitch assembly includes a magnetic sensing device for activating the starter.

24. The keyswitch assembly as set forth in claim 23 wherein said magnetic sensing device comprises a hall effect switch.

25. A method for preventing re-start attempts of a running engine which is coupled to a starter, comprising the steps of: measuring the rotational speed of an engine; converting the rotational speed of the engine to an output signal; comparing the output signal to a reference signal; and deactivating the starter when the output signal is at least equal to the reference signal.

26. The method of claim 25 wherein the output signal and the reference signal are voltage signals.

27. The method of claim 26 wherein a resistor provides the reference signal.