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Title:
DIESEL ENGINE STARTING SWITCH AND CIRCUIT
United States Patent 3708683
Abstract:
A diesel engine pre-heating, starting and running switch and circuit is comprised of a three pole, three position switch connecting the battery source to the engine starter, the electric fuel actuator and auxiliary equipment, the pre-heating glow plugs and a safety circuit that can be energized only when the engine is running, the fuel actuator can be energized only in the run and start positions of the switch, the starter can be energized only in the start position of the switch, and the glow plugs can be energized only in the pre-heat and starting positions of the switch.


Inventors:
HOWLAND L
Application Number:
05/142582
Publication Date:
01/02/1973
Filing Date:
05/12/1971
Assignee:
Thermo King Corporation (Minneapolis, MN)
Primary Class:
Other Classes:
123/179.21, 290/38R
International Classes:
F02P19/02; F02B3/06; (IPC1-7): F02N11/00
Field of Search:
290/37,38 123
View Patent Images:
US Patent References:
3551686STARTER SYSTEM FOR A DIESEL ENGINE1970-12-29Koehler
3514621SOLID STATE CRANKING MODULE1970-05-26Farmer et al.
3502895ELECTRIC FUEL PUMP CONTROLS1970-03-24Ballou
3382671Control for gas turbine emergency power system1968-05-14Ehni
Primary Examiner:
Simmons G. R.
Claims:
I claim as my invention

1. A diesel engine pre-heating, starting and running switch and circuit comprising, a three position switch having first, second and third poles, a source of current, a starter solenoid, an electrically operated engine fuel actuator, at least one engine pre-heating glow plug, a safety circuit having a normally closed contact to be connected to be energized only when the engine is running, means connecting said fuel actuator in series with said normally closed contact and the contacts of a main control switch to one terminal of said source, at least one alarm safety switch having normally open contacts, means electrically connecting together the first and second poles of said three position switch, means connecting said third pole to said one terminal of said source, means connecting the second and third switch positions of said first pole in series with said normally closed contact and said main switch to said one terminal of said source, means connecting the second position of said second pole in series with the said safety circuit and said at least one safety switch normally open contacts to the other terminal of said source, means connecting the third position of said second pole in series with said starter solenoid and the other terminal of said source, and means connecting the first and third positions of the second pole of said switch in series with said at least one glow plug to the other terminal of said source whereby said starting solenoid is connected to be energized only when the three position switch is in the third position, said at least one glow plug is connected to be energized to pre-heat the engine only when said switch is in the first or third positions, and said safety circuit is connected to said at least one safety switch only when said switch is in the second position.

2. The invention of claim 1 in which the three position switch is spring biased to the second position for normal running of the engine.

3. The invention of claim 1 in which said at least one safety switch includes a thermally operated engine high temperature switch.

4. The invention of claim 1 in which said at least one safety switch includes a low oil pressure switch whose contacts are closed when engine oil pressure is lower than desired.

5. The invention of claim 2 in which said at least one safety switch includes a thermally operated engine high temperature switch.

6. The invention of claim 2 in which said at least one safety switch includes a low oil pressure switch whose contacts are closed when engine oil pressure is lower than desired.

Description:
CROSS-REFERENCE TO RELATED APPLICATION

So far as it is known, this invention is not related to any pending patent applications.

BACKGROUND OF THE INVENTION

Truck and railroad car refrigeration systems are often powered by auxiliary diesel engines that are self-contained with the system. These engines are designed to run unattended for relatively long periods of time and therefore are provided with safety switch circuits to shut-off the engine in the event of a system malfunction such as low engine oil pressure, high engine temperature, or some other failure of the system including the refrigerant gas pressure conditions or the like. As is well known, a diesel is comparatively difficult to start and is usually pre-heated with one more glow plugs or the like before attempting to start the engine. During the pre-heating and the starting of the diesel engine, the safety circuits should be disabled since there would normally be little or no engine oil pressure at that time. A simple starting switch and circuit to provide the aforementioned starting functions in the desired and correct sequence is therefore needed and the arrangement should be such as to inactivate any safety circuits during the pre-heating and starting of the engine.

PRIOR ART

Applicant is not aware of any prior patents disclosing the starting switch and circuit of this invention.

SUMMARY

A three position, three pole starting switch that may, if desired, be spring biased to the second position designated as the running position, with the first position designated as a pre-heat position and the third position designated as a start position is provided. In the first or pre-heat position of the switch, only the pre-heating glow plugs are connected to the battery source and the safety switch circuits are not energized or connected to the battery source in any manner. In the second or running position of the switch, the electric fuel actuator is connected through normally closed safety relay contacts and a main running control switch to be energized by the battery source. Also, the operating coil of the safety relay is then connected through normally open safety switch contacts in a manner to be energized by the source if any one of the safety switches is closed by a system fault during normal running of the engine such as low engine oil pressure and the like. Thus while the engine is running and the start and running switch is in the running position, the safety relay coil may be energized whenever any of the normally open safety switches are operated to close their contacts. Therefore, when the safety relay is thus operated, the electric fuel actuator will be deenergized to stop the engine since the normally closed safety relay contacts will then be open. When the starting and running switch is in the third position, only the flow plugs together with the engine starter solenoid and the electrical fuel actuator will be connected to be energized through the normally closed contact of the safety relay, and the safety relay coil is not connected in a manner to be possibly energized by any one of the alarm switches as previously described.

Further objects, features and the attendant advantages of the invention will be apparent with reference to the following specification and drawings in which the sole FIGURE is a schematic wiring diagram partly in block outline showing the three position, three pole, starting and running switch and the circuit of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The three position starting and running switch of the invention is shown at 10 and is provided with three poles 11, 12 and 13. Pole 11 has three positions 11A, 11B and 11C. Similar poles 12 and 13 have respective three positions 12A, 12B, 12C and 13A, 13B and 13C. Each of the three switch poles 11, 12 and 13 are ganged to be operated together and if desired, may be centered by centering springs 14 and 15 to the second position 11B, 12B and 13B which may be designated as the normal running position of the switch. Poles 11 and 12 are electrically connected together by the wire connection 16. Pole 13 is electrically connected by the wire connection 17 to one terminal 18 of the battery source 19 whose other terminal is grounded at 20.

A main or running control switch 21 similar in function to the conventional ignition switch of an automobile engine is connected to the one terminal 18 of the power source 19 and through normally closed contacts 22A of the safety relay 22 to the second position 11B for the first pole 11 of the switch 10. The second position 11B of the first pole 11 is also connected to the third position 11C by means of the wire connection 23. Therefore, when the main switch 21 is closed, the electric fuel actuator 30 will be energized through the normally closed contacts 22A of the safety relay 22, considering that its other terminal is connected to the other terminals of the battery source 19 at ground 20. Also, any auxiliary equipment that is to be electrically energized during the running of the engine such as shown at 31 will be energized the same as the electric fuel actuator 30 so long as the main switch 21 is closed and the safety relay 22 is not energized.

One of one or more pre-heating glow plugs is shown at 40 and may be connected to the one terminal of the battery source 20 and ground in series with either the first or third positions 13A and 13C for the third pole 13 of the switch 10. Thus, when the starting and running switch 10 is in either the first and pre-heating position 13A, or in the third and starting position 13C, the glow plugs 40 will be connected to the battery source 19 to be energized for pre-heating the diesel engine.

The second or running position 12B for the second pole 12 of the starting and running switch 10 is connected by the wire connection 24 in series with the operating coil of the safety relay 22 and any one of the safety switches such as the oil pressure switch 25 or the high water temperature switch 26 to the other grounded terminal 20 of the battery. Thus, when the diesel engine is running and the starting and running switch 10 is in the running position, i.e., the second position, the safety relay coil 22 can become energized in the event of operation and closure of either one of the normally open safety switches 25 or 26. For example, if the oil pressure for the diesel engine should drop below a safe level, the switch 25 will close to complete the operating circuit for the safety relay coil 22 which will then operate to open its normally closed contacts 22A and deenergize the electric fuel actuator 30 and auxiliary equipment 31 thus stopping the engine. The safety relay 22 is a typical bi-stable circuit breaking relay switch as well known in the art, which, when operated to open its' circuit breaking contacts 22a will not reclose such contacts until the contacts are manually moved to the contact closed position. An example of such a relay is the subminiature circuit breaker switch known as the SM-3 series sold by the Heinemann Electric Co. of Trenton, New Jersey as advertised in their bulletin number 3504 issued in December, 1965. It will be noted that the safety relay 22 cannot be operated unless the starting and running switch 10 is in the running position with the circuit completed through contacts 11B, pole 11, pole 12 and contacts 12B. Also it will be noted that the fuel actuator 30 can be energized only when the starting and running switch 10 is in either the second or third positions, i.e., running or starting positions, through the circuits including contacts 11B or 11C and pole 11. Also it will be noted that when the switch 10 is in the first or pre-heat position only the glow plug 40 is connected to be energized and no other circuits may be energized from the source 19.

Various modifications will occur to those skilled in the art. For example, although a safety relay 22 had been specifically described, it will be obvious to anyone skilled in the art, that various well known forms of safety circuit breakers and devices such as heat operated switches may be used to be energized and operated when abnormal conditions such as low oil pressure are encountered during the running of the engine with the switch 10 in the run position.