GB2054991A - Device for starting diesel engine having a preheating chamber - Google Patents

Abstract

A device for starting Diesel engine in cold weather comprises a temperature sensor 25 which, after a time which is longer or shorter depending on the sensed environmental temperature, cuts off the current flow to the pre-heating resistors 24 of the engine preheating chamber while simultaneously causing current to be fed by a timer 27 to the engine-starting electric motor 28. <IMAGE>

Description

SPECIFICATION Device for starting diesel engines having a preheating chamber This invention relates to a device for starting the Diesel engines having a preheating chamber.

It is commonly known that the starting of Diesel engines involves difficulties, especially when the engine is cold, so that such difficulties are exalted in winter time, when the environmental temperatures are low. In order to offset such drawbacks, Diesel engines have been constructed, having a preheating chamber wherein resistors are located in order to heat the preheating chamber beforehand prior to starting the engine. In the embodiments known heretofore, such preheating resistors had to be switched on by an appropriate manual control and the time during which the resistors were on was left to the user's appreciation: obviously, the user maintained such resistors on in winter for a time longer than that adopted for the warmer seasons.This arbitrary criterion in selecting the on time of the resistors for preheating, prior to starting the Diesel engine, involved, as can be readily understood, a number of shortcomings.

An object of the present invention is to offset the above enumerated troubles while providing a device for starting a Diesel engine fitted with a preheating chamber, said device requiring of the user nothing else than switching the start key on and providing automatically to maintain the preheating chamber heating resistors on as a function of the environmental temperature and for a time sufficient to ensure a reliable start up of the Diesel engine.

Having this object in view, according to the invention, a sensor is provided which is influenced by the environmental temperature and by the current flowing through the preheating chamber heating resistors, said sensor being adapted to cut off the current flow in the preheating resistors after a heating time the duration of which is more or less long consistently with the environmental temperature, the device being simultaneously adapted to send current to the start-up motor of the Diesel engine.

The sensor may operate by expansion of liquids gases or temperature-responsive metals and can control, either directly or indirectly via electric, hydraulic or like means, a switch capable of sending current to the start-up motor.

For heating the sensor by the current flowing through the preheating resistors of the preheating chamber, the sensor, which, for example, may be encapsulated in a metal casing, can directly be inserted in the circuit through which said current flows, or, as an alternative, it can be indirectly heated by a coiling applied onto it and inserted in said circuitry.

According to an advantageous embodiment of the present invention, the devide has a circuit in which there are inserted the sensor and the preheating resistors, said circuit comprising the contact of a relay which can be energized by the starting key and which remains self-energized through another circuit which comprises a selfenergization contact for same relay, as well as the contact of the switch commanded by the sensor, said contact of the switch being normally closed and being opened by the sensor as the latter has become heated to the temperature required for starting the Diesel engine, the closure position of said contact being automatically obtainable by the sensor until such time as it has not yet attained the temperature suitable for starting, said contact being resettable, as an alternative, through a separate control member, such as a manual control.Of course, the sensor should be so positioned as to be influenced by the environmental temperature, in the same way as the Diesel engine itself.

The device according to the invention is particularly adapted to start Diesel engines of vehicles on road or rail and can be fed by the usual storage battery.

An exemplary practical embodiment of the invention will be described in more detail with reference to the accompanying drawing, the single Figure of which is illustrative of the circuitry diamgram of the device in question.

As can be seen in the diagram, the device is fed by a storage battery 10, for example that of a motor car on which the pre-chambered Diesel engine has been installed.

A starting key, 11, is capable of shifting a movable contact 12, from the normal position in which it closes the contact 14, to the position in which it closes, instead, the contact 13. The movable contact 12, which is connected to the (+) pole of the battery 10, can feed with current a relay 1 5, the coil of which is connected, at one side, to the contact 1 3 and, at the other side, to the (-) pole of the battery 10.

The movable core 1 6 of the relay 1 5 (in the deenergization condition of the relay the core closes the contacts 17, 18), closes, in the energized position of the relay 15, the contacts 19, 20. The contacts 19, 20 are simultaneously inserted in a first circuit of self-energization of the relay 1 5 (said self-energization circuit comprising the contacts 21 and 22 of a switch 23), and in a second circuit which comprises the electric resistors 24 intended to the preheating chamber of the Diesel engine, the resistor having, serially arranged therewith, a sensor 25. The sensor 25, via a control rod 26, can open the switch 23 and cut off the connection between the contacts 21 and 22 thereof.

Lastly, a circuit is provided, which comprises in serial arrangement, the movable contact 12 to be actuated by the starting key 1 the contact 14, the contacts 17, 18 of the relay 15 and a timer 27, the latter being capable of feeding with current the start-up motor 28. A pilot lamp, 29, is connected in parallel with the coil of the relay 15.

In the example shown, the sensor 25 is directly inserted in the circuit through which the current flows which likewise flows also through the preheating resistors 24, inasmuch as the metallic casing of the sensor is also exploited as a resistor, to the ends of which the circuit wires are connected.

It is obvious, however, that the sensor might have, coiled thereon, an appropriate coil serially connected to the resistor 24 in the circuit described above.

Also the direct command of the switch 23 by a rod 26 of the sensor 25 could be replaced by an indirect command through electric, hydraulic or other like means.

The sensor, 25, 26, as itself, is a device which can be easily found commercially and operates by thermal expansion of liquids, gases or metals. Any of such devices can be used for this invention provided that it has properly been calibrated for the requirements of the practical application envisaged herein. More particularly, what counts is that it delivers a command when in the preheating chamber of the Diesel engine to be started there has been attained, as a function of the environmental temperature and of the heating supplied by the preheating resistors, a temperature which is sufficiently high to start the Diesel engine concerned.

It should be observed, moreover, that the timer 27 is of any conventional make which is adapted to remain constantly fed with current and which, to snap and to send current for a preselected time to the start up motor 28, necessitate a current pulse after a cutoff of the circuit in which it has been inserted.

The operability of the device described in the foregoing is extremely simpie.

After having made sure that the closure of the contacts 21, 22 of the switch 23 (if the closure is not automized) has been restored, a pulse is given by turning the start key 11 to the relay 1 5 through the contacts 12, 13. The relay 1 5 is energized and remains self-energized through its own contacts 19, 20 and through the contacts 21, 22 of the switch 23. Simultaneously, current is fed, via the contacts 1 9, 20, to the preheating resistors 24 and the same current flows also through the sensor 25. The latter becomes heated within a time which is longer or shorter consistently with the current flow and the environmental temperature: once that the preselected temperature which is necessary and sufficient to start the Diesel engine has been attained, the rod 26 causes the switch 23 to become open. By so doing, the energization is cut off to the relay 1 5: the latter, by closing of its contacts 1 7, 1 8 and through the contacts 12, 14 (already closed, delivers a pulse to the timer 27. Timer 27 then send current, for a preselected time (a few seconds) to the start up motor.

As can be appreciated, the device according to the invention is extremely simple and requires only the actuation of the starting key, whereafter the heating of the preheating chamber is automatically obtained for the requested time consistently with the environmental temperature prior to giving current to the start up motor.

Claims (12)

1. A device for starting pre-chambered Diesel engines the chamber being heated by electric resistors, said device comprising a starting key and a start up motor and being characterized in that it is equipped with a sensor responsive to the environmental temperature and to the current flowing through said electric resistors, said sensor being adapted after a longer or shorter heating time as a function of the current flow and the environmental temperature, to cut off the current flow through said resistors and simultaneously to cause current to be sent to the start up motor.

2. A device according to Claim 1, characterized in that the sensor operates by expansion of liquids, gases or metals.

3. A device according to Claim 1, characterised in that the sensor is fitted with a metallic casing which is inserted, to act as a resistor, serially with the preheating chamber heating resistors.

4. A device according to Claim 1, characterized in that a coiling is wrapped onto the sensor body, said coil being serially connected with the preheating resistors of the preheating chamber.

5. A device according to Claim 1, characterized in that the sensor and the preheating resistors are inserted in a circuit which comprises a contact of a relay capable of being energized by the starting key and adapted to be maintained self-energized through another circuit comprising a selfenergization contact for the relay and a contact of a switch which can be commanded for opening by the actuator of said sensor.

6. A device according to Claim 5, characterized in that the actuator member of said sensor directly commands the opening of said switch.

7. A device according to Claim 5, characterized in that the actuating member of said sensor indirectly commands the opening of said switch through electric, hydraulic and other like means.

8. A device according to Claim 5, characterized in that the resetting of the closed position of the switch is commanded automatically by the sensor.

9. A device according to Claim 5, characterized in that a manual control member is provided for resetting the closure position of the switch.

10. A device for starting a diesel engine such device being constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. A diesel engine incorporating a device according to any one of Claims 1 to 10.

12. A diesel powered vehicle incorporating an engine according to Claim 11.