Anti-after-burning system in an internal combustion engine

Abstract: The known anti-after-burning system in an internal combustion engine provided with a governor device, in which a governor spring (109) is stretched between a governor lever (103) and a governor control lever (105) and said governor lever is connected to a carburettor throttle lever (101) and a stoppage device for stopping an engine by grounding a primary wire of an ignition circuit, is improved. The governor control lever is provided with a grounding section (113) for grounding the primary wire of the ignition circuit as a result of rotation to an engine low-speed side. The governor lever and one end of the governor spring are connected so as to be relatively rotatable and so as to have a freedom only with respect to the direction of contraction of the governor spring. Furthermore, the governor spring is constructed in such manner that when the governor control lever is at the position for grounding the primary wire of the ignition circuit, a coiled portion of the governor spring may butt against the governor lever to contrain rotation of the governor lever in the direction of opening the carburettor throttle valve.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to an anti-after-fire system applicable to an industrial engine provided with a governor device. Description of the Prior Art: As one example of an anti-after-fire system in the prior art, an engine stopping and controlling system disclosed in Japanese Utility Model Publication No. 1-28282 (1989) will be explained with reference to Figs. 9 to 13. Among these figures, Fig. 9 is a front view showing an engine directly coupled to a rotary machine, Fig. 10 is a front view showing an anti-after-fire system in an enlarged scale, Fig. 11 is a schematic plan view as viewed from the above, which shows the state where a throttle is set on a high-speed side, Fig. 12 is a schematic plan view as viewed from the above, which shows the state where a throttle is held on a low-speed side as a result of excitation of a solenoid upon no loading, and Fig. 13 is a schematic view as viewed from the above, which shows the state where upon stoppage of an engine, a stop button is press-actuated; and thereby a plunger having returned to a solenoid side and having moved a throttle to a low-speed side is held. In these figures, reference numeral 11 designates an engine, numeral 12 designates a rotary machine such as an electric generator, a welding machine or the like which is directly coupled to the engine to be driven, numeral 13 designates an air cleaner, numeral 14 designates a carburettor, and numeral 15 designates a governor mechanism, in which a governor spring 19 is stretched between a governor control lever 18 and a governor lever 17 pivotably supported by a governor shaft 16 which is pushed and rotated as a result of movement of a governor weight, a governor sleeve and the like not shown. One end of this governor lever 17 and a throttle lever 20 of the carburettor 14 are connected by means of a governor rod 22 wound by a rod spring 21. In this illustrated engine, by a resilient force of the governor spring 19 caused by rotational adjustment of the above-mentioned governor control lever 18, the governor lever 17 is made to swing to a high-speed side, and consequently, the throttle lever 20 is normally set at the high-speed side. In addition, reference numeral 23 designates a solenoid fed with electric power from an engine charging coil (in the case where a rotary machine driven by an engine is an electric generator, it could be an electric generator), which is provided with a plunger 24 that is held free except for the time of magnetic excitation, this plunger 24 is connected to the governor lever 17 directly or via a rod 25, and provision is made such that when the engine 11 is not loaded, the plunger 24 is attracted and restored by exciting the solenoid 23 and the governor lever 17 and the throttle lever 20 set at the high-speed side may be moved to the low-speed side. It is to be noted that while the plunger 24 is held free except for the time of magnetic excitation in the illustrated engine, it could be modified in such manner that an internally contained spring may be provided in the solenoid 23 and normally it may move forwards and project. The above-described engine is provided with a stoppage switch 26 for stopping rotation of the engine by grounding a primary wire of an ignition circuit. This stoppage switch 26 has a contact connected via a cable to a primary wire of an ignition circuit and a ground side contact provided within a main body 27, on the other hand a contact piece is provided on a bottom surface of a switch actuator 28 mounted at a surface aperture of the main body 27 in a projected condition, thus the switch 26 is adapted to be turned on or off by contact or separation of this contact piece to or from the above-mentioned contacts, and the aforementioned switch actuator 28 is biased in the direction for separation by means of a return spring 29 contained within the main body 27. In addition, the actuator 28 of the above-mentioned switch 26 has a holding rod 30 provided at its bottom portion as extended therefrom so as to project from the bottom surface of the main body 27, and it is adapted to project and retract through the bottom surface of the main body 27 as a result of sliding in the approaching direction caused by pressing operation of the actuator 28 and sliding in the separating direction caused by a biasing force of the return spring 29. Then, this stoppage switch 26 is mounted in the proximity of the outer circumference of a projected plunger 24 of the solenoid 23 by means of a bracket 31, and a holding groove 32 engageable with the holding rod 30 is formed circumferentially or in a spot shape on the outer circumference of the plunger 24 opposed to the tip end of the holding rod 30 of the above-mentioned switch actuator 28 when the plunger 24 has been attracted and restored by excitation of the solenoid 23 upon no loading of the engine. The arrangement is such that as a result of projection of the holding rod 30 caused by pressing the switch actuator 28 upon stoppage of the engine (upon no loading), the holding rod 30 is engageably inserted into the holding groove 32 of the plunger 24 which has been attracted and restored, and while the switch actuator 28 is being pressed, the restored condition of the plunger 24 can be maintained against the resilient force of the governor spring 19 even if the solenoid 23 is demagnetized. In such construction, upon loading of the engine 11, as shown in Fig. 11 the solenoid 23 is in a demagnetized condition, so that the governor lever 17 is made to swing by the governor control lever 18 and the governor spring 19 so as to set the throttle lever 20 to the high-speed side. On the other hand, upon no loading of the engine 11, as shown in Fig. 12 the solenoid 23 is excited through an electric wiring not shown and attracts and restores the plunger 24 against the resilient force of the governor spring 19 which is set on the aforementioned high-speed side, and accompanying the attraction and restoration, the governor lever 17 and the throttle lever 20 are moved to the low-speed side. Upon stoppage of the engine, after the above-described no load condition shown in Fig. 12 has been established, the stoppage switch actuator 28 is pressed against the return spring 29, and as a result of its contact piece coming into contact with the respective contacts of the ignition circuit primary wire and the ground side, the ignition circuit primary wire is grounded, hence rotation of the engine would gradually slow down and the solenoid 23 having attracted and restored the plunger 24 would be demagnetized, but due to pressing of the switch actuator 28, the holding rod 30 is projecting and engageably inserted into the holding groove 32 on the outer circumference of the attracted and restored plunger 24 as shown in Fig. 13, and therefore, while the switch actuator 28 is kept pressed, the plunger 24, the governor lever 17 and the throttle lever 20 can be maintained on the low-speed side against the resilient force of the governor spring 19. Accordingly, the above-described arrangement can preclude the disadvantage that upon stoppage of an engine, rotation of the engine 11 would gradually slow down, accordingly the solenoid 23 which has attracted and restored the plunger 24 to the low-speed side against the governor spring 19 biasing to the high-speed side would be demagnetized, hence in spite of rotation of the engine (ignition plugs are not sparking) the governor lever 17 and the throttle lever 20 would return to the high-speed side, and unnecessary fuel would be sucked in great quantities. However, the above-described anti-after-fire system in the prior art involves the following problems. That is, due to the fact that a solenoid is utilized in order to prevent excessive suction of fuel after stoppage of feeding of electric energy to an engine, an electric energy source for exciting the solenoid becomes necessary. Accordingly, the above-described system is applicable only to an engine provided with a battery or an engine-driven type electric generator, and it cannot be applied to an engine not provided with an electric energy source. SUMMARY OF THE INVENTION: It is therefore one object of the present invention to provide an improved anti-after-fire system in an internal combustion engine, which can prevent after-fire caused by excessive suction of fuel, and which is applicable to an engine not provided with an electric energy source, that is, an engine not equipped with a battery or an engine other than an engine-driven electric generator. According to the present invention, there is provided an anti-after-fire system in an internal combustion engine provided with a governor device, in which a governor spring is stretched between a governor lever and a governor control lever and the governor lever is connected to a carburettor throttle lever, and a stoppage device for stopping an engine by grounding a primary wire of an ignition circuit; which system is improved in that the governor control lever is provided with a grounding section for grounding the primary wire of the ignition circuit as a result of rotation to an engine low-speed side, i.e. as a result of operating the engine at a low rotational speed, the governor lever and one end of the governor level are connected so as to be relatively rotatable and so that the end of the spring engages the governor lever in a direction of extension of the spring and it is free to move away from the governor lever in a direction of contraction of the spring, and further, the governor spring is constructed in such manner that when the governor control lever is at the position for grounding the primary wire of the ignition circuit, a coiled portion of the governor spring may butt against the governor lever to constrain rotation of the governor lever in the direction of opening the carburettor throttle valve. In other words, in order to achieve the afore-mentioned object, the anti-after-fire system according to the present invention is constructed in such manner that a governor control lever is made to ground the primary wire of the ignition circuit at the engine low-speed side, that is, in the direction of decreasing the resilient force of the governor spring, the engagement between the governor lever and the governor spring is made rotatable and constrained only in the direction of increasing the resilient force of the governor spring, and by selecting the interval between the engaging position of the governor spring with the governor lever and its coiled portion smaller than the stroke of the control lever between engine low-speed and engine stoppage, at the engine stoppage position a buckling force of the governor spring is made larger than a compression force of the governor spring resulted from rotation of the governor lever caused by the governor force, so that the carburettor throttle may not open. According to the present invention, owing to the above-described structural feature, the following advantages are obtained. That is, by constructing a grounding portion of an ignition circuit for stopping an engine so as to act upon a low-speed side of a governor control lever of a control apparatus as interlocked with the governor control lever, a carburettor throttle valve opening just before stoppage of the engine takes a position close to full opening. Under the condition where an ignition plug does not spark after grounding of the primary wire, though the governor lever generates an action force in the direction of opening a carburettor throttle valve by means of a governor mechanism as a result of lowering of a rotational speed of an engine, since the governor lever and the governor spring are constrained in the aforementioned direction (in the direction of contraction of the governor spring), the governor lever would not move, and the carburettor throttle valve is held in the condition close to full closure. Consequently, even under an unburnt fuel-air mixture gas sucking condition caused by inertial rotation of an engine while the ignition plug is not sparking, the amount of the unburnt fuel-air mixture gas sucked by the engine itself is minimized, also the amount of fuel in the unburnt fuel-air mixture gas is also minimized, thus excessive suction of unnecessary fuel is prevented, and further, it becomes possible to prevent after-fire caused by that fuel. The above-mentioned and other objects, features and advantages of the present invention will become more apparent by reference to the following description of one preferred embodiment of the present invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Fig. 1 is a general side view of one preferred embodiment of the present invention; Fig. 2 is a plan view of a governor lever engaging section and a governor spring portion; Fig. 3 is a general side view similar to Fig. 1 at the time of a high-speed heavy-load operation; Fig. 4 is a general side view similar to Fig. 1 at the time of a high-speed light-load operation; Fig. 5 is a general side view similar to Fig. 1 at the time of a low-speed heavy-load operation; Fig. 6 is a general side view similar to Fig. 1 at the time of a low-speed light-load operation; Fig. 7 is a general side view similar to Fig. 1 at the time of stoppage of an engine; Fig. 8 is a cross-section view taken along line Z-Z in Fig. 1 as viewed in the direction of arrows; Fig. 9 is a front view showing an engine directly coupled to a rotary machine in the prior art; Fig. 10 is an enlarged front view of a control apparatus in Fig. 9; Fig. 11 is a plan view showing the condition where a throttle is set on the high-speed side; Fig. 12 is a plan view showing the condition where a solenoid is exited at the time of a no-load operation and a throttle is held on the low-speed side; and Fig. 13 is a plan view showing the condition where a stoppage button has been press-actuated upon stoppage of an engine, thereby a plunger has been restored to the side of a solenoid, and the throttle has been moved to the low-speed side. DESCRIPTION OF THE PREFERRED EMBODIMENT: Now, one preferred embodiment of the present invention will be described with reference to Figs. 1 to 8. In Figs. 1 and 2, reference numeral 100 designates a carburettor, which is provided with a throttle valve (not shown) for adjusting a feed rate of fuel to a combustion chamber, and the throttle valve is controlled in opening and closing by rotation of a throttle lever 101. A governor rod 102 is engaged with one end of the throttle lever 101, and the other end of the governor rod 102 is engaged with a governor lever 103. The governor lever 103 is fixedly secured to a governor shaft 104, and the arrangement is such that according to a rotational speed of a governor gear (not shown), it may rotate in the clockwise direction when a rotational speed of an engine falls but it may rotate in the anticlockwise direction when a rotational speed of the engine rises. The governor lever 103 is provided with an engagement section 110 formed in such shape that a governor spring 109 may be given a freedom only in the direction of contraction and a slit D larger than a wire diameter d of the governor spring 109 is opened, and one end of the governor spring is formed in such shape 121 that it may be engaged with the engagement section 110 but it may not generate a constraining force in the torsional direction. On the other hand, the other end of the governor spring 109 is engaged with an adjusting screw 111 for the highest rotational speed of the engine rotatably mounted to a screw mount section 125 provided at one end of a control lever 105, and they form such structure that as a result of rotation of the control lever 105, the governor spring 109 may be stretched or contracted by a necessary amount. The control lever 105 is provided with a hole 106 for engagement with a control cable (not shown) and a grounding section 130 for an ignition circuit primary wire of the engine, and also it is provided with an engagement section 133 for a return spring 132 which biases the control lever 105 in the direction of stopping the engine. The control lever 105 is rotatably mounted to the control panel 107 by means of a calking pin 108 or the like. Reference numeral 113 designates a ground terminal of an ignition circuit primary wire of the engine, numeral 114 designates a bracket made of insulator for holding the ground terminal 113, and numeral 115 designates a lead wire and a plug receptacle. It is to be noted that as shown in Fig. 2 the engagement section between the governor spring 109 and the governor lever 103 is constructed so as to have dimensions fulfilling the following relations: B > A > D > d and L > ℓ . In the above-described construction, during normal operation of the engine, as shown in Figs. 3 to 6, the portion of the control apparatus and the portion of the carburettor throttle valve are rotated depending upon a loading condition of the engine and a desired rotational speed of the engine. More particularly, when the engine is operated at a high speed, the control lever 105 is rotated by a control cable (not shown) in the clockwise direction as viewed in Figs. 3 to 7, and the carburettor throttle valve is maintained at such position 101 that a tension of the governor spring 109 and a torque in the anticlockwise direction of the governor lever 103 generated by a governor gear (not shown) may balance with each other. That is, during a heavy-load operation when the engine consumes a lot of fuel, when the fuel fed to the engine is little (when the carburettor throttle valve is at the position in the closing direction, since the rotational speed of the engine is lowered, as shown in Fig. 3 a torque in the clockwise direction is applied to the governor lever 103, as a result the carburettor throttle lever 101 is directed in the opening direction, but on the contrary during a light-load operation when the engine does not consume so much fuel, since the carburettor throttle lever 101 is at a position in the closing direction as compared to the case shown in Fig. 3, as a result, as shown in Fig. 4, the governor spring 109 is in a stretched condition in spite of the same control lever position. Likewise, when the engine is operated at a low speed, also for the same position of the control lever 105, the position of the carburettor throttle valve 101 is moved in the opening or closing direction depending upon a loading condition of the engine, and as a result, a constant rotational speed is maintained regardless of the loading condition of the engine (See Figs. 5 and 6). On the other hand, with regard to the operation of the subject system after stoppage of the engine, that is, after grounding of the ignition circuit primary wire, as shown in Figs. 7 and 8, the ground terminal 113 comes into contact with the grounding section 130 provided at one end of the control lever 105, hence generation of sparks by the engine ignition device ceases, and a rotational speed of the engine falls gradually. As a result of falling of a rotational speed of the engine, a torque in the clockwise direction is generated in the governor lever 103 by the governor mechanism, and though this torque acts so as to rotate the throttle lever 101 in the opening direction, since the coiled portion of the governor spring 109 butts against the engagement section 110 of the governor lever 103, the governor lever is restrained from rotating, and consequently, the carburettor throttle lever 101 is maintained at its closed position. Accordingly, in the engine cylinders after cease of generation of sparks, there never occurs suction of fuel caused by the carburettor throttle valve opening gradually, and after-burning caused by unnecessary fuel also would not be generated because the fuel itself is not present. It is to be noted it has been fully confirmed by experiments conducted by the inventors of this invention that the torque of the governor lever resulted from lowering of a rotational speed of the engine is not so large as making the governor spring 109 buckle, and by selecting the dimensions of the engagement section so as to fulfil the relation of L > ℓ , inconveniences such as disengagement of the governor spring upon stoppage of the engine would also not arise. As will be obvious from the detailed description of one preferred embodiment of the present invention above, according to the present invention, owing to the fact that in an internal combustion engine provided with a governor device in which a governor spring is stretched between a governor lever and a governor control lever and the governor lever is connected to a carburettor throttle lever, and a stoppage device for stopping an engine by grounding a primary wire of an ignition circuit, the governor control lever is provided with a grounding section for grounding the primary wire of the ignition circuit as a result of operating the engine at a low rotational speed, the governor lever and one end of the governor spring are connected so as to be relatively rotatable and so that the end of the spring engages the governor lever in a direction of extension of the spring and it is free to move away from the governor lever in a direction of contraction of the governor spring, and further, the governor spring is constructed in such manner that when the governor control lever is at the position for grounding the primary wire of the ignition circuit, a coiled portion of the governor spring may butt against the governor lever to contrain rotation of the governor lever in the direction of opening the carburettor throttle valve; the following advantages are obtained. At the position for stopping the engine, the carburettor throttle valve is maintained at a closed position, hence suction of unnecessary fuel caused by inertial rotation of the engine after cease of generation of sparks by an ignition circuit is prevented, and consequently, after-fire caused by the unnecessary fuel also can be prevented without making use of an electrical energy source.

Claims: An anti-after-fire system in an internal combustion engine provided with a governor device, in which a governor spring (109) is stretched between a governor lever (103) and a governor control lever (105) and said governor lever (103) is connected to a carburettor throttle lever (101), and a stoppage device for stopping an engine by grounding a primary wire of an ignition circuit; characterized in that said governor control lever (105) is provided with a grounding section (130) for grounding the primary wire of said ignition circuit as a result of operating the engine at a low rotational speed, said governor lever (103) and one end of the governor spring (109) are connected so as to be relatively rotatable and so that the end of the spring (109) engages the governor lever (103) in a direction of extension of the spring (109) and it is free to move away from the governor lever (103) in a direction of contraction of the spring (109), and said governor spring (109) is constructed in such manner that when said governor control lever (105) is at the position for grounding the primary wire of the ignition circuit, a coiled portion of the governor spring may butt against said governor lever (103) to constrain rotation of said governor lever (103) in the direction of opening a carburettor throttle valve. An anti-after-fire system in an internal combustion engine as claimed in claim 1, characterized in that the conncecting portion of said governor lever (103) with said governor spring (109) is provided with an engagement section (110) having a slit (D) of larger width than the wire diameter of said governor spring (109) and is adapted to receive an end head portion (121) of said governor spring (109) and said engagement section (110) is engaged with said governor spring end head portion (121) having a larger dimension than said slit width in a relatively rotatable and freely movable manner. An anti-after-fire system in an internal combustion engine as claimed in claim 2, characterized in that the lenght of said engagement section (110) is made longer than the dimension between the end head portion (121) of the governor spring (109) and its coiled portion. An anti-after-fire system in an internal combustion engine as claimed in claim 1, characterized in that the other end portion of said governor spring (109) is connected to an engine rotational speed adjusting screw (111) mounted to said governor control lever (105).

Inventors: KOBAYASHI KAZUYUKI C O NAGOYA, KOBAYASHI, KAZUYUKI, C/O NAGOYA MACH. WORKS, MITS.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1991
Main classification: F02D9
IPC codes: G02B3, F02D11, F02D9, G02B25, F02D17, F02D31