Detailed Description of the Invention
The present invention relates to an automatic control system for an internal combustion engine, and more particularly to an automatic control system for automatically controlling the operation of a gasoline-powered internal combustion engine of a load device, such as a freezing unit mounted on a refrigerator car.
For portable or installed gasoline powered internal combustion engines used for driving load devices such as a freezing unit, an automatic control system for readily and surely controlling the operation of the engine in close relationship to varying operating conditions of the load device has been required.
An object of the present invention is to provide an automatic control system for a gasoline-powered internal combustion engine of a load device, which system is arranged to automatically control the operation of the engine in close relationship to varying operating conditions of the load device.
With the above and other objects in view, the present invention including other features and advantages thereof will become more clearly understood from the following description of a preferred embodiment in connecton with the accompanying drawings, in which:
FIG. 1 is a control circuit embodying the present inventions, wherein parts of an engine to be controlled are illustrated together with the system units, and
FIG. 2 is an illustration of respective part blocks of the system units.
Referring now to FIG. 1 of the drawings, there is schematically shown a preferred embodiment of an automatic control system according to the present invention for automatically controlling the operation of a gasoline-powered internal combustion engine of a load device 16a. A battery 1 has two terminals, one of which is grounded and the other of which is connected to an actuating means such as a relay switch 2 for controlling a throttle valve, of an engine carburetor, and an actuating means such as main relay switch 3 and a sub relay switch 4 for controlling a starter of the engine, all through a line 5. A starter motor 6 is connected to the line 5 via the main relay switch 3, which has a solenoid coil connected to the line 5 via the sub relay switch 4. A solenoid coil 7 is connected to the line 5 via the relay switch 2, and is energized when the switch 2 is closed, whereby the throttle valve provided in the engine carburetor is wholly closed, and enriched air mixture flows through a by-pass provided in the carburetor for initiating the starting of the engine. An alternating current generator 8, which is connected and driven by the engine, is connected to the line 5 through a rectifier 9 as shown in FIG. 1. An ignition coil 10 and an ignition plug 11 are connected to the line 5 through a gate switch included in an automatic control system detailed hereinafter.
The automatic control system is illustrated in dashed lines in FIG. 1, and in general includes a first driving unit 12 of controlling the starter motor 6, a second driving unit 13 for controlling the throttle valve of the carburetor, a switching unit 14 responsive to an input signal supplied from a first sensing means or sensor such as a relay switch 16 connected to the load device 16a and producing operating signals which are supplied to the first and second driving units 12 and 13, and a second sensing means or monitor unit 15.
As shown in FIG. 2 the switching unit 14 comprises a gate 14a which is connected to the first sensing means or relay switch 16 to receive the input signal therfrom. The relay switch 16 has a relay coil (not shown) which is energized to close the switch 16, thereby to produce the input signal, in respone to a given operating condition of the load device, for example, when the room temperature of a freezing container included in a refrigerator car reaches a predetermined level. Upon receiving the input signal, the gate 14a produces an operating signal which is delivered through an amplifier 14b to the ignition coil 10 and to the first and second driving units 12 and 13 via lines 17 and 18.
The first driving unit 12 comprises a reset circuit 12a for receiving the operating signal from the switching unit 14, a non-stable multi-vibrator 12b and a counter 12c consisting of a flip-flop circuit, so as to produce an intermittent output signal which is delivered from the vibrator 12b to an amplifier 12d, through which the signal is supplied to a solenoid coil 19 of the sub relay switch 4. The output signal from the amplifier 12d is also supplied to the counter 12c which counts the number of the intermittent output signals within prescribed times, for example, three times.
Accordingly, the energizing operation of the solenoid coil 19 is repeated a prescribed number of times until the engine is started by the starter motor 6.
The second driving unit 13 comprises a reset circuit 13a for receiving the operating signal from the switching unit 14 and a timer 13b having a time lag by which the timer 13b continues to supply an output signal through an amplifier 13c to the solenoid coil 7 for a prescribed time interval, so that the throttle valve is closed for a predetermined time interval during startng of the engine.
The monitor unit 15 constituting the second sensing means for sensing the engine speed includes a circuit 15a for generating a signal having a potential varying in proportion to the frequency of the generator 8 connected to the engine, and a schmitt circuit 15b for supplying a speed discriminator signal through an amplifier 15c to the reset circuit 12a of the first driving unit 12 and the reset circuit 13a of the second driving unit 13 (as indicated in FIG. 2) when the voltage of the signal indicative of the engine speed exceeds a prescribed value. The speed discriminator signal is supplied through the amplifier 15c to both of the reset circuits 12a and 13a via lines 20 and 21 (FIG. 1), so that the operating signals are eliminated, thereby causing the solenoid coil 19 and the solenoid coil 12a for the switch 2 to be de-energized.
The automatic control system in this embodiment further includes another monitor unit 22 for detecting failure in the starting of the engine, caused by accidents such as a wet-plug and cold air, when the repeated setting operation counts more than the prescribed number of times times, for example, three times determined in the first driving unit 12. The monitor unit 22 comprises a static flip-flop circuit 22a to which the output signal is supplied from the counter 12c unless the engine is driven by itself within the three times repeating setting operation, and then which supplies an inverted signal through an amplifier 22b and a line 23 to the gate 14a, so that the gate 14a is rendered inoperative, whether or not the input signal is supplied by the relay switch 16, whereby the current for the ignition coil, and the solenoids of the starter and throttle is cut off.
The monitor unit 22 further comprises a manual control switch 22c disposed near the driver or monitor so that the closing of the switch 22c results in supplying a reset signal to the circuit 22a to eliminate the inverted signal from the circuit 22a thereby returning the gate 14a in an original position.
The automatic control system may further include a power distributing unit 24 which comprises a charging circuit 24a with an AC - DC converter, and a constant voltage stabilizing circuit 24b, in the case where the battery 1 and an external power source 38, such as a commercially available alternating current source, are alternatively used for performance of the load device.
The external power source 38 is connected to the charging circuit 24a through a transformer 25, and the battery 1 may be connected to the interval between the circuits 24a and 24b so as to distribute the current supply through the unit 24 to the desired units via line 24c, and in reverse to be charged when the apparatus is subject to the external source.
In the case where the either the battery of the external electric source is always used, the automatic control system may be provided with an automatic power-charging unit 26 which acts to cut off the operating signals from the first and second driving units when the load device is subject to the external electric source.
Therefore, the power supplied from the external electric source enters a voltage detector 26a via a line 27 and is supplied to the gate 14a through a timer 26b, so that the gate 14a is closed by the counter signal from the timer 26b. The timer 26b has a time lag by which the gate 14a, after a prescribed time interval developed from the power stoppage is returned to an original position due to the extinguishing of the counter signal from the timer 26b, so that the engine is controlled to the start position.
In this embodiment, there may be provided an electric-heating element 28 for an automatic choke of the engine carburetor which is energized together with the ignition coil 10.