Internal-combustion engines – Engine speed regulator – Having condition responsive means with engine being part of...
Patent
1980-01-31
1982-10-19
Nelli, Raymond A.
Internal-combustion engines
Engine speed regulator
Having condition responsive means with engine being part of...
123358, G05D 1362, G06F 1520, F02D 3100
Patent
active
043544673
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to speed responsive systems and more particularly to speed responsive systems for vehicles whereby the vehicle may be kept at or about a predetermined speed.
Systems are known for automatically controlling a motor vehicle to run at a predetermined speed which is set by the driver. Once the speed has been selected and set by the driver, the system operates automatically to hold the vehicle at that speed, subject, of course, to the speed being within the capability of the vehicle having regard to the gradient of the road and similar factors.
It is also known in such systems to provide means for sensing various operating parameters of the vehicle so as to disable the speed control system automatically when one or more of these parameters changes in such a manner as to indicate that it is no longer safe or expedient to maintain the vehicle under automatic control of the speed control system. For example, it is known to disable a speed control system when the driver operates the brakes of the vehicle, such disabling being carried out, for example, by monitoring an electrical signal dependent on conditions in the brake lamp circuit of the vehicle.
An object of the invention is to provide an improved vehicle speed control system.
A more specific object of the invention is to provide a vehicle speed control system having improved means for disabling the system automatically in the event of certain conditions arising.
BRIEF SUMMARY OF THE INVENTION
In accordance with the invention, a vehicle speed control system is disclosed which is arranged, when rendered operative, to control the engine of the vehicle so as to tend to hold the vehicle to run at a desired speed, and is characterised by means responsive to the speed of the engine of the vehicle to render the system inoperative when the engine speed becomes outside a predetermined limit.
DESCRIPTION OF THE DRAWING
A vehicle speed control system embodying the invention will now be described, by way of example only, with reference to the accompanying drawing which is a circuit diagram, partly in block form, of the system.
DESCRIPTION OF PREFERRED EMBODIMENTS
The FIGURE shows the engine 10 of the motor vehicle driving the propeller shaft 12 through a gearbox or transmission 14, the speed of the engine being regulated by means of a throttle control 15. The control 15 will normally form part of the engine carburetter and is arranged to be adjustable by the driver's throttle pedal in the usual way. In addition, however, it is connected to be adjustable by means of a throttle actuator 16.
It will be appreciated that in relation to the application of the system to a diesel engine powered vehicle, the throttle control 15 would be replaced by the equivalent engine power control device.
The engine speed of the vehicle is sensed by means of a line 17, which, in this example, is connected across the engine contact breaker 18 through which the ignition coil 19 of the engine is supplied by the vehicle electrical system. In this way, a pulsating electrical signal exists on line 17 whose frequency is dependent on the engine speed. It will be appreciated that various other means can be used for producing an electrical signal dependent on the speed of the engine.
The speed dependent signal on line 17 is then passed to a frequency-to-voltage converter 22 which produces an output voltage Vs on a line 21 dependent on engine speed. In this embodiment, it is assumed that the signal Vs is inversely proportional to engine speed.
The circuit 22 may take any suitable form. It may, for example, comprise a limiting amplifier for converting the pulse signal on line 17 into a rectangular wave of constant amplitude, followed by a smoothing circuit.
The speed-dependent signal Vs is then fed, via a switch 34, to a memory 36 and is also fed directly to a filter 38. The memory 36 and the filter 38 produce respective outputs Vm and Vf which are both fed to an error amplifier 42. The latter drives a drive circuit 46 which in turn drives the thr
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patent: 4177516 (1979-12-01), Mason
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patent: 4211193 (1980-07-01), Cox et al.
Borton Roland K.
Noddings John
Associated Engineering Limited
Nelli Raymond A.
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