US2055209A - Internal combustion engine-electric power unit - Google Patents

Description

C. SCHAER Sept. 22, 1936.

INTERNAL COMBUSTION ENGINE-ELECTRIC POWER UNIT Filed March 17, 1933 INJENTU R 6 KW J/QZW BY I ATI'D RN Eh/ Patented Sept. 22, 1936 srsres INTERNAL COMBUSTION ENGINE-ELECTRIC POWER UNIT Charles Sehaer, Langenthal, Switzerland, assignor to firm Sulzer Freres Societe Anonyme, Winterthur, Switzerland Application March 17, 1933, Serial No. 661,238 In Switzerland March 24, 1932 Claims.

This invention relates to internal combustion engine-electric power plants particularly, though not exclusively, for the propulsion of vehicles.

An internal combustion engine-electric power 5 plant according to the invention comprises a control generator driven by the engine, and control apparatus actuated in accordance with the output voltage of the control generator so as to control the excitation current of the main current generator. In this way the speed of the engine will be maintained constant at the value desired in spite of load variations.

The control apparatus may comprise a relay or relays actuated in accordance with the output voltage of the control generator and means controlled by the relay so as to regulate the excitation current of the main generator. Alternatively the control apparatus may comprise an electric motor having two opposed windings one of which is energized by current derived from the control generator and the other by current derived from a constant voltage source, and means operated by the motor to control the excitation current of the main generator.

In the accompanying drawing-- Figure 1 illustrates diagrammatically and by way of example one construction according to the invention,

Figures 2 and 3 show respectively two modifications of the control apparatus illustrated in Figure 1 and Figure 4 illustrates another construction also according to the invention.

Figure 5 illustrates still another construction according to the invention.

In the construction illustrated in Figure 1 the power plant comprises an internal combustion engine I which drives a main current generator 2 the excitation circuit 3 of which is energized either in shunt or from a separate source. A

control generator 4, also driven by the engine I has an excitation circuit 5 energized from a battery 8, the control generator 4 supplying a circuit 1 containing two relays 8 and 9 and a resistance ill variable by means of a contact arm I l. Each of the relays 8 and 9 controls two pairs of contacts, one pair associated with a circuit [2 and the other pair with a circuit l3, the circuit l2 including a solenoid [4 Whilst the circuit ill includes a solenoid Hi. The solenoids l4 and I5 actuate, as hereinafter described, a piston valve It so as to control a piston ll by regulating the supply of pressure medium to a cylinder l8 within which the piston IT can reciprocate. The piston 55 valve I6 is normally held in its central position as shown by centering springs l9. The piston I1 is operatively connected by a rod 20 to a pivoted contact arm 2! of a rheostat 22 whereby the excitation current flowing through the field winding 3 of the main current generator 2 can be regulated.

The engine I is furnished with a centrifugal governor 23 whereby the fuel supplied to the engine is regulated in accordance with the load thereon, the tension of the loading spring or is springs of the governor 23 being adjustable by means of the arm ll acting through a rod 24, bellcrank lever 25 and plunger 26.

The relays 8 and 9 are such that the armature of the relay 8 will be raised only when the output 15 voltage of the control generator 4 exceeds a predetermined normal value, whilst the armature of the relay 9 will be raised when the output voltage of the control generator has reached a value somewhat below the said normal. 20

With the parts in the positions shown in Figure 1 the output voltage of the control generator 4 is substantially normal, the relay 9 being in its raised position and the relay 8 in its lower position. If now the speed of the engine increases, 25 due for example to a decrease in the load on the main generator 2, the output voltage of the control generator 4 will increase to a value above normal whereby the armature of the relay 8 will be raised, 1'. e. to the position corresponding to 30 that of the relay 9. The circuit l2 will in this way be closed so that the solenoid l 4 will move the piston valve I 6 to the right as viewed in Figure 1 and pressure medium will be delivered to the cylinder l8 so as to move the piston I! to the left. In 5 this way the resistance 22 will be decreased and the excitation current through the field winding 3 increased, the load on the engine and therefore the speed of the engine and of the control generator 4 being thereby restored to normal. The 40 output voltage of the control generator 4 is in this way restored to normal and the relay 8 will return to the position shown so that the solenoid l 4 will be deenergized and the piston valve l6 returned under the action of its control springs l9 to its 45 central position shown in the drawing. The parts are then in their normal positions shown in Figure 1.

If now the speed of the engine decreases due, for example, to an increase in the load on the main generator 2, the output voltage of the control generator 4 will decrease to such a value below normal that the armature of the relay 9 Will descend to the position corresponding to that of the relay 8 whereby the solenoid l5 will be energized and the piston valve EB moved to the left as viewed in Figure 1. Pressure medium will thus be admitted to the cylinder 53 on the left or the piston ll which will thereupon be moved to the right so as to increase the resistance 22 and decrease the excitation current flowing through the field winding 3. The load on the engine will thus be decreased so that the engine speed and the speed of the control generator will be restored to the normal value. The armature of the relay g will then return to the position shown in Figure 1 and the solenoid it will thus be deenergized so that the piston valve it will return to its normal or central position.

Arrangement of the relays 8 and 9 so as to be operated at voltages of the control generator respectively above and below normal voltage, with V a constant resistance in the circuit l and constant excitation current flowing through the winding 5 as above described, will result in the normal voltage of the control generator l being produced at predetermined torque and engine speed. The unit may however be adjusted for any given torque between full load and idle running by moving the lever ll so as to adjust the value of the resistance to whereupon a different engine speed will be required to produce the normal output voltage from the control generator 6, the tension of the governor loading spring being simultaneously adjusted through the rod 2 3 and bell crank lever 25. When the engine is not furnished with a governor and the fuel supply is manually regulated the speed of the engine for a given normal output voltage of the control generator t may be adjusted by varying the resistance it.

The circuits l2 and is may, if desired, be controlled by vibration regulators, or the like. Further instead of employing two relays as above described a single relay El (Figure 2) may be employed. The relay 2? is such that with the normal outputvoltage from the control generator i the armature of the relay 2? will be in the central positionrshown whilst, with the output voltage of the control generator 5 at a value above or below normal the said armature will be in the raised or lowered position respectively so as to energize the circuit E2 or 53.

As shown in Fig. 3, the piston valve l6 may be actuated by two opposed coils 23, 28 both arranged to influence an armature 3G operatively connected to one end of the piston valve 56. The coil 28 is connected across the control generator l whilst the opposed coil 29 is connected across the battery 5. Thus, while the voltage of the circuit 7 is equal to that of the battery 6 the piston valve it will remain in its central position shown in the drawing thereby cutting off the supply of pressure medium to the cylinder l8. When the voltage of the circuit 7 exceeds that of the battery 6 however the influence of the coil 28 on the armature (it will predominate and the piston valve it will be moved to the right as viewed in Figure 3 so that the piston i? will be moved to the left and the resistance 22 decreased. Conversely, when the voltage of the circuit l falls below that of the battery 6 the influence of the coil 29 on the armature 39 will predominate and the piston ill will be moved to the right so as to increase the resistance 22 and decrease the current flowing through the field winding 3. In either case the engine speed necessary to produce the desired normal output voltage from the control generator l will 'be restored by the adjustment of the field current flowing through the field winding 3 so that the normal output voltage of the control generator 4 will be restored and the piston valve 56 returned to its central position.

In the construction illustrated in Figure 4 control of the resistance 22 is eiiected by means of an electric motor generally indicated at 3! and comprising a winding 32 connected across the control generator i and an opposed winding 33 connected across the battery 6. When the voltage across the winding 32 exceeds that across the opposed Winding 33 the armature 35 of the motor 3! will be rotated in one direction thereby transmitting movement through a gear 36 to the contact arm M of the resistance 22 which will thus be, in effect, decreased. Conversely, when the voltage across the winding 33 exceeds that across the opposed winding 32 the armature 35 will be rotated in the opposite direction to efiect an increase of the resistance 22. A variable resistance Si in the field circuit of the control generator can be adjusted so as, in effect, to vary'the engine speed which is to be maintained. Instead of providing the opposed field windings 32 and 33 of Fig. 4, opposed armature windings may be used as shown in Fig. 5 at 32st on armature 35a and at 330, on armature 3517.

W ith a view to limiting the range of regulation or? the resistance 22, for example during starting of the power unit, means may be provided which, when operated by the driver, causes the contact arm 2i or the motor 31 to be locked in position. To this end a coil 43 may be energized through a circuit 6G fromthe drivers cabin, the coil 43 when energized holding a latch 3E out of the path of a nose l2 provided on the transmission mechanism 36. When during starting, the coil 43 is deenergized the latch Lil will fall by gravity so as to lie in the path of the nose i2 whereupon the contact arm M which, when the unit is inoperative will occupy the position at which the value of the resistance 22 is a maximum, cannot be moved beyond the position indicated at I. The value of the resistance 22 cannot therefore be decreased below a predetermined value until the driver raises the latch ll by energizing the coil 53. In this way the possibility of an excessive flow of current through the field winding 3 of the main generator 2 during starting of the unit is precluded.

Instead of locking the contact lever 21 in this manner an additional resistance actuated from the drivers cab may be switched into the excitation circuit 3 of the main current generator 2, so that the driver may control the maximum speed to which the vehicle automatically adjusts itself.

It will therefore be seen that in a power plant according to the invention the speed of the internal combustion engine will be maintained substantially constant in spite of variations in the load thereon.

It will be understood that the constructions above described are given by way of example only and that details may be modified. Thus, for example, instead'of employing relays such as those illustrated inFigures l or 2 any other suitable form of relay such, for example, as that of the polarized or, electron type may be employed. The means for actuating the contact arm of the rheostat associated with the field winding of the main generator may be operated by hydraulic or pneumatic means and, instead of employing a piston valve for regulating the supply of pressure medium to the piston operatively connected to the rheostat valves, for example of the poppet type, may be employed. Further, if desired, ad- I5 justment of the resistance in circuit with the field winding of the main generator may be effected by means of an electric motor. Instead of employing a centrifugal governor as above described the fuel supply may be regulated manually and a safety regulator provided.

I claim:

1. In an engine-electric power set, an internal combustion engine, a main electric generator driven by said engine and having an excitation circuit, a device operated by a pressure medium for adjusting the resistance of said circuit, a control generator driven by said engine, and control means for controlling said device comprising a valve for controlling the flow of pressure medium to said device, and two electromagnetic relays responsive to different voltages of said control generator, said relays actuating said valve to thereby cause the resistance for regulating the current of said main generator to be adjusted.

2. In an engine-electric power set, an internal combustion engine, a main electric generator driven by said engine and having an excitation circuit, a variable resistance in said excitation circuit for controlling the excitation current, a control generator driven by said engine, and control means responsive to variations in the output voltage of said control generator, but operable only after said variations have reached a predetermined amount, said control means controlling the operation of a power-operated device, said power-operated device being operable to vary said resistance.

3. A set according to claim 2, in which said power operated device has a valve for controlling said device, and control relays are provided for cooperating with said valve for varying the torque and the speed of said engine.

4. In an engine-electric power set, an internal combustion engine, a main electric generator driven by said engine and having an excitation circuit, a variable resistance in said excitation circuit for controlling the excitation current, a control generator driven by said engine, and control means responsive to variations in the output voltage of said control generator, but operable only after said variations have reached a predetermined amount, said control means controlling the operation of a power-operated device, said power-operated device being operable to vary said resistance, said control means in controlling the working of the power-operated device causing a subsequent and further variation of the value of said resistance only when the output voltage of said control generator differs from its predetermined value by an amount substantially equal to that which originally caused the operation of said control means.

5. In an engine-electric power set, an internal combustion engine, a main electric generator driven by said engine and having an excitation circuit, means for controlling the excitation circuit, a control generator driven by said engine, means for regulating the speed of the engine to give a desired normal output voltage of the control generator, and control means responsive to variations in the output voltage of said control generator, but operable only after said variations have reached a predetermined amount, means operable by said control means for varying the resistance in said excitation circuit, and said control means being operable to adjust the resistance in said excitation circuit until after the output voltage of said control generator has again reached substantially its normal value.

CHARLES SCHAER.

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