CHOKE FOR ENGINES

Abstract: This invention is characterized in that a starting fuel pump (49) for use in sucking a fuel from a fuel tank (25) and supplying the fuel to a starting nozzle port (41) of a carburetor (17) is driven by a fuel supplying electric motor (53). In or­ der to start the engine, the motor (53) is rotated to suck the fuel from the fuel tank (25) by means of the pump (49) and sup­ ply the same to the starting nozzle (41), whereby the density of the gaseous mixture is increased to render the gaseous mix­ ture easily ignitable. Thus, the engine can be started by either a starting electric motor or a recoil starter.

Description: The present invention relates to a fuel supply system for engine which facilitates the start-up by augmenting the concentration of the fuel at the time of starting the engine. A conventional fuel supply system for engine to facilitate the start-up by augmenting the concentration of fuel at the time of starting the engine is arranged, as shown in Fig. 1 and Fig. 2, by pivotally mounting, with shaft 7, a choke valve 5 for opening and closing a suction port 3 of a carburetor 2 provided on an intake port 1 of the engine so as to be freely oscillatable in the direction perpendicular to an intake gas passage 9. By restricting the area of the suction port 3 through an oscillatory operation of the choke valve 5, negative pressure created in the intake gas passage 9 is increased by the intake force of the engine. As a result, the amount of the fuel jetting out of the main nozzle port 11 opening its mouth to the intake gas passage 9 is increased, so that the concentration of the fuel contained in sucked gas is also increased, whereby facilitating start-up of the engine. With such a conventional structure, however, operation was cumbersome because it was necessary to appropriately operate the opening of the choke valve in addition to the starting operation for rotating the crankshaft, and moreover, it was necessary to quickly return and release the choke valve after the engine was started. Furthermore, a large force was required for starting the engine due to lowering of the intake pressure caused by the closing of the choke valve. In the prior document JP-A-6235047, in addition to the main nozzle, a starting fuel nozzle is provided through which a starting fuel is supplied from a starting fuel reservoir into the intake gas passage in addition to the main fuel at the start of the engine. At low temperature start a fuel injection valve is opened by negative intake pressure to inject fuel in the intake gas passage and at high temperature a control plate is lowered by a heat sensitive member so that the fuel injected in the intake gas passage is deviated towards a porous material and the flow of starting fuel through the intake gas passage is hindered. The fuel supply system of such prior document does not result simple and effective and furthermore starting fuel is wasted. Object of the present invention is to overcome all the drawbacks mentioned above. Such an object is achieved by a fuel supply system for an internal combustion engine, wherein the fuel is supplied from a fuel tank into an intake air passage communicating with an engine intake port, comprising a main fuel passage through which a main fuel is supplied from the fuel tank into the intake air passage, a starting fuel passage provided separately from the main fuel passage, a starting fuel reservoir filled by a starting fuel pump which sucks the fuel from the fuel tank, through the starting fuel passage a starting fuel being supplied from the starting fuel reservoir into the intake passage in addition to the main fuel at the start of the engine, characterised in that it further comprises a control valve located in the starting fuel passage between the starting fuel reservoir and the intake air passage and connected to an engine temperature sensor for controlling the quantity of fuel flowing in the starting fuel passage by adjusting the opening of the control valve in accordance with the engine temperature. Thanks to such control valve which controls, in a particular position, the flow of starting fuel according to the engine temperature, a simple and effective fuel supply system is provided and a fuel saving is obtained. Three embodiments of the present invention will be described thereinafter. With reference to the annexed drawings : Figg. 1,2 are a side cross sectional view and a front view, respectively, of the conventional fuel supply system described above; Fig. 3 is an explanatory path diagram for showing the construction of a first embodiment of the invention; Fig. 4 is an explanatory diagram for showing the electrical circuit of said first embodiment; Figg. 5,6 are explanatory diagrams for a second and a third embodiment, respectively, of the invention. In the embodiments illustrated a carburetor is shown connected to an intake port of an engine. These embodiments are equipped with a starting nozzle port opened to an intake gas passage of the carburetor and a starting fuel pump for supplying the fuel in a fuel tank to a fuel reservoir, whereby the fuel in the fuel reservoir is transferred to the starting nozzle port via a starting nozzle passage by means of the pressure of the starting fuel pump or the sucking power of the engine, and a fuel motor for driving the starting fuel pump and a starting motor for starting the engine are interlocked so as to actuate them in succession. With a single pressing of a switch, the fuel motor drives the starting fuel pump to cause it to suck the fuel in the fuel tank to be supplied to the fuel reservoir. After the fuel reservoir is filled with the fuel, fuel is jetted out of the starting nozzle port by actuating the fuel motor to drive the fuel pump concurrently or by the sucking force of the engine. In this manner, the fuel motor and the starting motor are actuated automatically in sequential fashion by a single operation of the switch. With reference to Figs. 3,4 the carburetor 17 is fixed via an insulator 15 to the intake port 13 of the engine by means of bolts (not shown). A main nozzle port 19 which is opened to the intake gas passage 18 communicated with the suction port 13 is communicated with a fuel chamber 21 provided in the lower part of the carburetor 17. The fuel chamber 21 is connected to a main fuel passage 27 which communicates the chamber with the fuel tank 25 via a diaphragm pump 23. In the diaphragm pump 23 a diaphragm 33 defines a pressure chamber 29 and a pump chamber 35, separate one with respect to the other. The diaphragm 23 is vibrated corresponding to the positive and negative pressures in the crankcase (not shown) transmitted through a communicating tube 31 which is communicated with the crankcase of the engine. The main fuel passage 27 is communicated with the pump chamber 35 via check valves 37 and 39. The starting nozzle port 41 is opened to the intake gas passage 18 which is communicated with the fuel tank 25 via the starting fuel passage 43. The starting fuel passage 43 is communicated via check valves 45 and 47 with the starting fuel pump 49. The starting fuel pump 49 uses batteries 51 as the power supply and is rotatably driven, via the push-button type switch 57 and a main control device 65, in the forward as well as the reverse direction by the fuel motor 53. One end of the starting fuel pump 49 is communicated via a fuel reservoir 67 with a position in the starting fuel passage 43 intermediate between the check valves 45 and 47 while the other end is communicated with the fuel tank 25. Further, adjacent to the cylinder (not shown) of the engine, there is provided a sensor 59 for detecting the temperature, connected to the control valve 63 provided in the starting fuel passage 43 via the controller 61 connected to the switch 57, in order to control the quantity of the fuel that flows in the starting fuel passage 43 corresponding to the temperature of the cylinder. The main control device 65 is constructed as in the following. Namely, a first controller 69 connected to the switch 57 is connected in parallel with a second controller 71 and a transistor TR₁, and the transistor TR₁ is connected via the power supply (batteries) to a relay RL₁. The second controller 71 is connected in parallel with transistors TR₂, TR₃ and TR₄, and the transistors TR₂, TR₃ and TR₄ are connected via relays RL₂, RL₃ and RL₄, respectively, to the power supply. A starting motor 55 is connected via a contact r₄ of the relay RL₄ to the power supply 51, and the fuel motor 53 is connected via a contact r₃ of the relay RL₃ for switching the forward and reverse rotations to the power supply. Between the contact r₃ and the power supply 51 there are connected in parallel a contact r₁ of the relay RL₁ and a contact r₂ of the relay RL₂. A temperature switch 73 is connected in series with the contact r₂. An electronic buzzer 75 is connected in parallel with the fuel motor 53. A timer is incorporated in the first controller 69 in such a way as to energize the transistor TR₁ and disconnect the current to the transistor TR₁ after elapse of a predetermined length of time, and then to switch electrical energization to the second controller 71. With the above construction, when the switch 57 is depressed to start the engine, the transistor TR₁ is actuated to energize the relay RL₁ to connect the contact r₁. The fuel motor 53 is rotated forwardly to cause the starting fuel pump 49 to rotate, and the fuel in the fuel tank 25 is sucked through the check valve 45 and the fuel reservoir 67 to the starting fuel pump 49, and is circulated to the fuel tank 25. After elapse of a predetermined time required for filling the fuel reservoir 67, the timer in the first controller 69 is actuated to disconnect the transistor TR₁ and the contact r₁. At the same time, the relays RL₂, RL₃ and RL₄ are energized by the transistors TR₂, TR₃ and TR₄, which action connects the contact r₂ and energizes the contact r₃ to rotate the fuel motor 53 in the reverse direction. Then, the starting fuel pump 49 is rotated in the reverse direction to cause the fuel in the fuel reservoir 67 to be sent through the check valve 47 to the starting nozzle port 41 to be jetted out into the intake gas passage 18. At the same time, the contact r₄ is connected to rotate the starting motor 55 which causes the engine to be rotated, thereby starting the engine. The fuel jetted from the starting nozzle port 41 is controlled by a command sent from the controller 61 to the control valve 63 to send appropriate amount of fuel corresponding to the temperature contained in the command by adjusting the opening of the control valve 63. Once the engine is rotated, the diaphragm 33 is vibrated in response to the variations of the pressure in the crankase of the engine, and the fuel in the fuel tank 25 is jetted out by the diaphragm pump 23 from the main nozzle port 19 into the intake gas passage 18, whereby sustaining the operation of the engine. When the push-button type switch 57 is opened, all of the relays RL₁, RL₂, RL₃ and RL₄ are de-energized, all of the contacts r₁, r₂, r₃ and r₄ return to their original positions and the starting motor 55 and the fuel motor 53 are brought to a stop. In addition, when the temperature of the engine or the surroundings is sufficiently high such that it does not require the fuel from the starting nozzle port 41, a temperature switch 73 located at an appropriate position is opened. Then, the fuel motor 53 will not be rotated in the reverse direction and the jetting of the fuel from the starting nozzle port 41 will not take place. Moreover, Fig. 5 shows another embodiment, wherein the fuel pump 49 does not rotate in the reverse direction and the fuel in the fuel reservoir 67 is sucked and jetted out of the starting nozzle port 41 by means of the sucking force of the engine. The sequential operation in which the starting motor is actuated with elapse of a predetermined length of time after the fuel motor is rotated is identical to the previous embodiment. Further, Fig. 6 shows a third embodiment wherein the discharge side of the starting fuel pump 49 is connected to the starting nozzle port 41, with the fuel reservoir 67 provided between the pump 49 and the port 41. It is analogous to the previous embodiment that the fuel motor 53 and the starting motor 55 are sequentially operated by means of a timer. Moreover, the present invention may be arranged, instead of using a timer, to operate the fuel motor and the starting motor sequentially by detecting the fuel in the fuel reservoir by means of a pressure switch or the like provided in the fuel reservoir. As described in the above, in these embodiments it is possible by a single pressing of the switch to actuate the fuel motor to supply the fuel to the fuel reservoir and then automatically actuate in sequence the starting motor of the engine. Thereby, it becomes possible to facilitate the ignition of the engine by augmenting the concentration of the intake gas through an increased jetting of the fuel into the carburetor, and to execute an easy and sure starting of the engine. It should be noted that in the aforementioned embodiments, the starting nozzle port 41 is provided separately from the main nozzle port 19, but the main nozzle port may be served also as the starting nozzle port.

Claims: A fuel supply system for an internal combustion engine, wherein the fuel is supplied from a fuel tank (25) into an intake air passage (18) communicating with an engine intake port (13), comprising a main fuel passage (27) through which a main fuel is supplied from the fuel tank (25) into the intake air passage (18), a starting fuel passage (43) provided separately from the main fuel passage (27), a starting fuel reservoir (67) filled by a starting fuel pump (49) which sucks the fuel from the fuel tank (25), through the starting fuel passage (43) a starting fuel being supplied from the starting fuel reservoir (67) into the intake air passage (18) in addition to the main fuel at the start of the engine, characterised in that it further comprises a control valve (63) located in the starting fuel passage (43) between the starting fuel reservoir (67) and the intake air passage (18) and connected to an engine temperature sensor (59) for controlling the quantity of fuel flowing in the starting fuel passage (43) by adjusting the opening of the control valve (63) in accordance with the engine temperature. A fuel supply system according to claim 1, wherein the control valve (63) is connected to the engine temperature sensor (59) via a controller (61). A fuel supply system according to claim 1, wherein the starting fuel passage (43) comprises a circulating passage for circulating the starting fuel to the fuel tank (25). A fuel supply system according to claim 1, wherein the starting fuel of the starting fuel reservoir (67) is supplied into the intake air passage (18) by the starting fuel-pump (49). A fuel supply system according to claim 4, wherein the starting fuel pump (49) is a reversible pump which, in a forward operation, sucks the fuel from the fuel tank (25) into the starting fuel reservoir (67) and, in a reverse operation, supplies the starting fuel from the starting fuel reservoir (67) into the intake air passage (18). A fuel supply system according to claim 5, wherein a check valve (45) is provided on the starting fuel passage (43) between the fuel tank (25) and the starting fuel reservoir (67), said check valve (45) allowing the flow of fuel from the fuel tank (25) to the starting fuel reservoir (67) and preventing the flow of fuel in the opposite direction. A fuel supply system according to claim 1, wherein the starting fuel of the starting fuel reservoir (67) is supplied into the intake air passage (18) by the sucking force of the engine. A fuel supply system according to claim 1, wherein a diaphragm fuel pump (23) is further provided, which communicates with a crankcase of the engine and supplies the main fuel from the fuel tank (25) into the intake air passage (18) through the main fuel passage (27) according to pressure variations within the crankcase. A fuel supply system according to claim 8, wherein a first check valve (39) is provided between the fuel tank (25) and the diaphragm pump (23) and a second check valve (37) is provided between the diaphragm pump (23) and the intake air passage (18), said first and second check valves (39,37) allowing the flow of fuel from the fuel tank (25) to the intake air passage (18) and preventing the flow of fuel in the opposite direction. A fuel supply system according to claim 5, wherein a control device (65) is provided for electrically controlling the starting fuel pump (49) so that, at the start of the engine, the starting fuel pump (49) is forwardly operated till the starting fuel reservoir (67) is filled and then is reversely operated.

Inventors: MOROOKA ISAO, WADA MINORU, YAMAGISHI TETSUO, MOROOKA, ISAO, WADA, MINORU, YAMAGISHI, TETSUO
Applicants: KOMATSU ZENOA KK, KOMATSU ZENOAH KABUSHIKI KAISHA
Application year: 1988
Main classification: F02M1
IPC codes: F02M1