JPH02248652A - Starter device of engine - Google Patents

Abstract

PURPOSE:To compact the whole engine by setting the starting possible rotating range to a low rotation less than 350r.p.m. to reduce the necessary capacities of a starter motor and a power battery, and disposing the battery on the lower side of a fuel tank. CONSTITUTION:An engine 11 is set in such a manner that it can be started at a low rotation lees than 350 r.p.m. to reduce the necessary capacities of a starter motor 16 and a power battery 17. The power battery 17 is disposed on the lower side of a fuel tank 12 disposed in the upper part of the engine body 11, and fastened to the engine body 11 by a bolt 27 without using any special bracket. The starter motor 16 is also disposed on the lower side of the fuel tank 12, and connected to a driven rotating member 23 on the extension of the crank shaft core P of the engine by a belt 24. Hence, the whole engine can be compactly constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an engine starting device, and particularly to one used in a four-stroke gasoline engine started by a starter motor.

BACKGROUND OF THE INVENTION FIG. 10 schematically shows a conventional starting device for a four-stroke gasoline engine of this type. Engine body (1)
A flywheel (4) integrally formed with a cooling fan (3) is attached to the crankshaft (2) which protrudes further. A ring gear (
5) is installed. A starter motor (6) whose main body has approximately the same length as the width of the engine main body (1) is attached to the side surface of the engine main body (1), and a drive shaft ( 7), a drive gear (8) is fitted in a movable manner.

When the starter motor (6) is driven, the drive gear (8)
protrudes onto the shaft (7) and meshes with the front ring gear (5), which connects the crankshaft (2) via the flywheel (4).
Rotate. Then, when the engine starts,
The drive gear (8) retracts to its original state and the ring gear (
5) has a latch structure that allows it to be disengaged from the engagement. As a power source for driving the starter motor (6), approximately half of the engine body (1) is provided with a separate battery of any size and connected to the starter motor (6).

Problems to be Solved by the Invention As mentioned above, a conventional four-cycle engine requires a starter motor (6) having a main body portion that is approximately the same width as the engine main body (1). When (6) was attached to the engine body (1), there was a problem in that the overall external size of the engine became very large. Additionally, in order to drive such a large starter motor (6), a similarly large power battery is required, and in the past, it was difficult to attach the battery to the engine body (1) as described above. However, there is a drawback that it must be kept separate. Furthermore, in the case of engines for mounting on work equipment, there are those with a hand starter specification and those with a starter motor specification, but in the case of a starter motor specification, a special space is required to mount the battery. Therefore, for example, it is difficult to easily mount a starter motor specification engine on a hand starter specification working machine, and there is also a drawback that wiring work between the battery and the starter motor is required.

In addition, some very small 2-cycle engines of 50cc or less have a small starter motor and battery attached to the engine body, but for 50cc to 250cc
Compared to a small 4-stroke gasoline engine,
There was no such thing, and it was impossible.

The present invention provides a starter motor and battery mounting structure that eliminates the disadvantages of conventional four-cycle gasoline engines as described above.

Means for solving the problem, that is, in order to achieve the above object, in the first invention of this application, the rotation range in which the engine can be started is set to a low rotation of 350 rpm or less, and the required capacity of the starter motor and its power source battery is reduced. The engine is small in size, and the battery is located below a fuel tank installed above the engine main body.

Further, in the second invention of this application, the starter motor is arranged below the fuel tank installed above the engine body, and is connected to the driven rotating member on the extension of the rotating shaft of the engine via the transmission means. This results in interlocking connections.

Moreover, in the invention of claim 3, there is provided an engine body in which a starter motor, a starter switch, a power source battery, and a hand starter are all installed.

According to the fourth aspect of the present invention, there is provided a starter motor in which the starter motor is directly engageable and detachable from the driven shaft for starting the engine without attaching the starter motor to the engine body.

In the above, as a means to make the starting rotation range of the engine a low rotation range of 35 orpm or less, it is necessary to automatically reduce the pressure in the cylinder at low rotation speeds, to use a carburetor that obtains an appropriate air-fuel ratio in the low rotation range, and to reduce the engine speed. The carburetor should be designed to obtain an air-fuel ratio suitable for ignition without the need for choke operation in the engine speed range, the ignition speed of the ignition device should be lowered, and the timing at which ignition timing can be avoided at low engine speeds (for example, Possible methods include retarding the engine to near dead center (near dead center) and increasing the secondary voltage of the ignition coil, which can be achieved by using some or all of these.

Effects According to the invention, the engine can be started even at low rotation speeds of 350 rpm or less, and as a result, the starter motor and battery are made smaller, and since the battery is placed below the fuel tank, The battery does not protrude from the engine body and can be stored compactly. In addition, in the second invention of this application, the starter motor is similarly miniaturized and placed below the fuel tank above the engine body, and similarly does not protrude much beyond the engine body. The whole can be stored compactly.

In addition, in the third invention of this application, since the starter motor, starter switch, power battery, and hand starter are all installed in the engine body, there is no need to make any changes to the working machine with the hand starter specification or starter motor specification. It can be installed without any problem. Furthermore, in the fourth invention of this application, the engine can be started by engaging the starter motor with the starting driven shaft of the engine body.

Embodiment FIGS. 1 and 2 show drawings of the entire engine showing an embodiment of the present invention, and with respect to the crankshaft center P,
This is an inclined four-stroke gasoline engine in which the cylinder centerline Q is inclined diagonally. A fuel tank (12) is located above the engine body (11) directly above the crankshaft center P.
is mounted, and an exhaust muffler (13) is mounted on the side above the cylinder head. A fan case (19) is attached to one side surface in the direction of the crankshaft center P, and a hand starter (for example, a recoil starter) (14) is further attached to the side surface of the fan case (19). The bottom of the fuel tank (12) on the exhaust muffler (13) side is recessed, and the starter motor (12) is installed in the recess (18).
16), its fuel tank (12) and engine body (1
1). As shown in FIG. 2, the drive shaft (20) of this starter motor (16)
is engaged with the internal teeth (22) of the drive pulley (21). This driving boo! A bell is placed between I (21) and the driven pulley (23) on the recoil starter (14) side.
(24) is wrapped around the drive shaft (20) to control the rotation of the drive shaft (20)! I am trying to decelerate to the J (23) side so that it travels 1-way. The V-shaped extension (26) of the recoil starter case (25) allows the above-mentioned bell) (24) and the drive boo! J (21) side is covered. On the other hand, a stay (28) is attached to the side surface of the engine body (11) in a direction perpendicular to the crankshaft center P via a pole (27), and this stay (28) allows the engine body (
A battery (17) is supported between the fuel tank (11) and the lower side of the fuel tank (12). A starter switch (29) for starting the starter motor (I6)
) is the starter motor (16) and battery (17).
It is disposed above the engine body (11) in a side surface portion below the fuel tank (12) between the engine body (11) and the fuel tank (12). Furthermore, a pull (30) for operating the recoil starter (14) is provided from a side surface of the recoil starter case (25) toward the side of the engine body (11) opposite to the air cleaner (15). It stands out.

As shown in FIG. 2, inside the fan case (19), a cooling fan (33) is installed at the end of the crankshaft (32).
and a flywheel (35) are integrally attached. And, the above-mentioned driven boo provided in the recoil starter case (25)! I (23) and a starter wheel (34) around which a lobe (33) pulled by the handle (30) is wound, each connected to the crankshaft (32) via a driven member (35). As a result, when the starter motor (16) is driven, the belt (2
4), the crankshaft (32) rotates, and on the other hand, when the handle (30) is pulled, the crankshaft (32) is rotated by the starter wheel (34). At that time, when the engine is started, the crankshaft (32) and its pulleys (23) or wheels (3
4) A clutch is provided to release the interlocking relationship with
Furthermore, in addition to that, passive boo! A latch mechanism is provided so that even if either one of the J (23) and the starter wheel (34) is rotated, the other does not rotate.

FIG. 3 shows that the starter motor (16) is attached to the recoil starter case (25) on the side of the recoil starter (14).
) to the crankshaft (32) via the reduction gear (41).
). patch! I (1
7) is located at the same position as in FIG.

FIG. 4 shows yet another embodiment of the invention, in which the starter motor (16) is separate from the engine body (11). First, inside the recoil starter case (25), a driving member (45) having internal teeth (43) is attached via a starting driven shaft (46). This driving member (45) and the driven member (35) on the crankshaft (32) side
) are connected via a clutch (47). On the side of the driven shaft (46), there is yet another deceleration shaft (4
B) are journalled in parallel, and a drive pinion (49) attached to this shaft (48) meshes with the internal teeth (43). Furthermore, another reduction gear (54) attached to the reduction shaft (48) and a drive pinion (50) attached to the driven wheel (46) are in mesh with each other. A starter motor (
16) is formed with a spline (51) that is inserted into and engaged with the end of the drive shaft (20). On the side of the recoil starter case (25), there is a dish-shaped motor receiving part (52).
), and an opening (53) corresponding to the end of the driven shaft (46) is formed in the coil starter case (25) surrounding the motor receiving part (52). That is, the drive shaft (20) of the starter motor (16) is inserted into this opening (53).
) to engage the spline engagement portion (51) of the driven shaft (46), and in this state, connect the starter motor (16).
), the drive pinion (50), reduction gear (54), drive pinion (49) and drive member (45
) is transmitted from the driven member (35) to the crankshaft (32) via the clutch (47). When the engine is started, the clutch (47) is disengaged and cannot be rotated from the engine side.

Furthermore, a rope (57) is provided around the outer periphery of the drive member (45).
) is attached to the Star Taboo IJ (5B), and this Boo! A one-way clutch (59) is installed between I (5g) and the drive member (45).

That is, the rope (57) is pulled by the handle (30) and this Start Taboo! When J (58) is rotated, the drive member (45) rotates in the same manner as described above, but even if this drive member (45) is rotated by the starter motor (1B), the starter pulley (58) does not rotate. It becomes. In this case, Star Taboo! Even if rotation is transmitted from l (58) to the pinion (49) and the reduction gear (54), if the starter pulley (58) is used for starting, the starter motor (16) is not connected, so no There is no inconvenience, and therefore a one-way clutch for preventing power from being transmitted from the starter pulley (5B) side is unnecessary.

Next, the starter motor (16) and battery (17)
) to be small enough to fit within the width of the recoil starter (14) as described above, and to enable starting in a low rotation range of 350 rpm or less will be described.

As is well known, in order to turn the engine crankshaft during startup, it is necessary for the piston to survive the compression process near top dead center, and this requires an extremely large amount of force.

To solve this problem, the exhaust valve or intake valve is forcibly opened to release the compression. In the case of the present invention, an automatic decompression device is used that automatically releases the compression at low speed rotation. By this, the starter motor (
1B) can be reduced. An example of such an automatic decompression device is a centrifugal automatic decompression device filed by the applicant of the present invention as Japanese Patent Application No. 11539/1984 (Japanese Patent Application Laid-Open No. 158976/1982). This device uses a centrifugal weight that is displaced as the camshaft rotates to move the bottle in the diametrical direction of the shaft, and this pin pushes the tappet up in the direction of releasing compression.At low rotations, the centrifugal weight automatically moves the bottle in the diametrical direction of the shaft. Since it moves in the direction of decompression, decompression at startup can be obtained without any special operation.

Next, FIG. 5 shows an electric circuit of an ignition power supply device used in the present invention. In the figure, the secondary coil (66) of the ignition coil (65) and the spark plug (67) are shown.
) are connected in series. On the other hand, the primary coil (68
), the collector and emitter side terminals of the transistor (69) are connected in parallel with its primary coil (68). Similarly, on both ends of the transistor (69),
The anode and cathode terminals of the thyristor (70) are connected in parallel, and the anode side of the thyristor (70) is further connected to the base of the transistor (69). Both terminals of the Zener diode (71) are connected to the thyristor (70
) are connected in parallel to the anode and cathode side terminals of the zener diode (71), and the anode side of the Zener diode (71) is also connected to the gate terminal of the silisk (70). FIG. 6 shows the voltage waveform generated in the primary coil (68). The voltage generator used in this embodiment is a flywheel magnet type that generates alternating current voltage as the flywheel rotates, and when the generated voltage is lower than the operating voltage VO of the Zener diode (71), , a voltage is applied to the base side of the transistor (69), and a current flows between the collector and emitter of the transistor (69). When the generated voltage exceeds the vO, a voltage is applied to the gate terminal of the thyristor (70), so a current flows between the anode and cathode of the thyristor (70) (in the direction of the dashed arrow in the figure), and the base of the transistor (69) The voltage decreases and the collector of this transistor (69)
The current flowing between the emitters is cut off. Therefore, 2
A large secondary voltage is generated in the next coil (66), causing the spark plug (67) to ignite.

As shown in FIG. 6, the voltage generated at the primary coil (68) changes depending on the engine speed. For example, when the engine speed is about 25 rpm, the voltage generated at the Zener diode (71) changes. operating voltage Vo. Therefore, the current flowing through the transistor (69) is not interrupted, and a large voltage cannot be generated in the secondary coil (66). Therefore, in this embodiment, a capacitor (72) as shown in the figure is provided in parallel with the Zener diode (71), and a detection circuit detects the peak point P of the voltage due to charge/discharge conversion of the capacitor (72).
As a result of this detection, during low rotations when only a voltage lower than the voltage Vo is generated, a signal is generated to release the conduction of the transistor (69) at the peak point P of the voltage, and the current of the primary coil (68) is generated. is cut so that it can be ignited.

Next, in order to prevent reverse rotation during low-speed starting, in this embodiment, in the flywheel magnet type ignition device, the shape of the iron core (73) around which the ignition coil (65) is wound is As shown in Figure 8, the ignition timing during low speed rotation is retarded. That is, in FIG. 7, the magnet (
A U-shaped iron core (73) with lips (75) (76) facing each other is provided at its tip.
) is fixed, and the ignition coil (65) is wound around this iron core (73). In this embodiment, the lip (7) located on the rear side of the flywheel (24) in the rotating direction
5) is made larger than the length 12 of the other lip (76), thereby making the length 11 of the primary coil (68
) is modified as shown in FIG. 8, and the amount of retardation at low rotations is made larger than that shown in FIG. 6. As shown in FIGS. 5 and 6, at low rotations of about 25 Or pm below the operating voltage vO,
The voltage peak point P is detected and a cutoff signal is generated based on this, but in the waveform of Fig. 8, two peak points, the first peak point P and the second peak point P, are detected. appear. In this case, if the cutoff is made at the first peak point P, the amount of retardation is still insufficient for the firing angle θ1 at the maximum rotation, and it is necessary to take a cutoff signal at the second peak point P. As a result, the amount of retardation Δθ=θ, -θ1 at low rotations relative to the maximum rotation range can be increased (and a sufficient amount of retardation can be taken to prevent the above-mentioned reverse rotation. The detection of the second peak point P is performed, for example, by using a judgment means for judging whether the peak point is the first peak point or the second peak point, and based on the judgment result of the judgment means, the MIIJ2 peak is detected. This can be easily realized by using a microcombiner equipped with a control means that generates a cutoff signal for the transistor at the point in time.The specific retardation amount Δθ with respect to the maximum rotation time performed in the example was 7 degrees.

In order to improve the ignition performance at low rotation speeds, in this embodiment, the voltage of the secondary coil (66) that fires the spark plug (67) is changed from the conventional 8KV/25 Orp.
m, thereby improving the ignition performance.

Now, even if it is possible to ignite at low rotation speeds without causing reverse rotation, if the carburetor cannot supply the appropriate amount of fuel with an air-fuel ratio into the cylinder at that low rotation speed. , cannot be ignited. Therefore, in this embodiment, in order to obtain an appropriate air-fuel ratio sufficient for ignition at a low rotation speed of 350 rpm or less, the diameter DI of the bench stiffness part (79) of the carburetor (78) is adjusted as shown in FIG. The nozzle (80) is made smaller than the conventional one to increase the inflow velocity of this part and to ensure that the fuel is sucked up from the nozzle (80). In addition, by selecting an appropriate combination of the air jet (81) outlet position and the nozzle (80) shape, an appropriate air-fuel ratio can be obtained at low rotation speeds, making it possible to reliably start the engine without choking even when it is cold. becomes possible.

By using all or some of these means in appropriate combination, it is possible to start with a small torque in a low rotation range of 350 rpm or less, and accordingly, the required capacity of the starter motor (16) can be reduced. It is possible to make the device much smaller than the conventional one, and the battery can also be made smaller as well.

Effects of the Invention As described above, according to the present invention, the starter motor and its battery can be made smaller by making it possible to start the engine at low rotation speeds, and as a result, the battery, which was conventionally placed separately, can be used as a fuel source in the engine body. Because it is located at the bottom of the tank, for example, when mounting it on a work machine,
There is no need for a special space for mounting the battery or a bracket for that purpose. In addition, if the starter motor is attached to the engine body, the starter motor and battery are already wired, and there is no need to wire them one after another when installing the work equipment or starting it. be. Furthermore, according to the second invention of this application in which the starter motor is attached to the engine body, the starter motor is miniaturized and placed below the fuel tank as described above, making the entire engine very compact. becomes. Furthermore, by equipping the engine with the battery, hand starter, and starter switch as described above, one type of engine can be used for both starter motor specifications and hand starter specifications, and even if the starter motor fails, It has the advantage of being easy to start using a hand starter even if the battery runs out or the battery dies. In addition, the fourth part of this application
In the invention, the starter motor is started by engaging and disengaging from the driven shaft for starting the engine, and the starter motor is removed after starting, so that, for example, when the crankshaft is in the starting state, If a clutch is provided to allow the starter motor to rotate from the crankshaft side, or if a hand starter is provided, this has the effect of eliminating the need for a clutch to prevent the starter motor from being rotated from the hand starter side. .

[Brief explanation of drawings]

Fig. 1 is a front view of the entire engine showing an embodiment of the present invention, Fig. 2 is a partially cutaway side view seen from the right side of Fig. 1, and Fig. 3 is another embodiment of the invention. FIG. 4 is a longitudinal sectional side view of main parts showing yet another embodiment of the invention, and FIG. 5 is a power supply circuit for an ignition device showing an embodiment of the invention. 1 is a graph showing changes in the generated voltage of an ignition device that performs ignition using a flywheel magnet method, and FIG. FIG. 8 is a graph showing the waveform of the generated voltage obtained by the power generating device of FIG. The installation of the starter motor is a cross-sectional plan view of the main parts of the engine showing the structure. (11) Engine body, (12) Fuel tank, (14) Recoil starter, (16) ... Starter motor, (17) ... Battery, (20) ... Drive shaft, (22) ... Crankshaft, (23) ... Driven pulley, (29) ... Starter switch, ( 46) ... Driven shaft for starting. Fig. 2 Fig. 7 Fig. 8

Claims (1)

[Scope of Claims] 1. The required capacity of the starter motor and its power battery is reduced by setting the engine startable rotation range to a low rotation of 350 rpm or less, and the battery is installed in a fuel tank above the engine body. An engine starting device characterized in that it is placed below the engine. 2. The engine can be started at a low rotation range of 350 rpm or less to reduce the required capacity of the starter motor and its power source battery, and the starter motor is placed below the fuel tank installed above the engine body. An engine starting device characterized in that the engine starting device is interlocked with a driven rotating member on an extension of the rotating shaft of the engine via a transmission means. 3. The engine can be started at a low rotation range of 350 rpm or less, reducing the required capacity of the starter motor and its power battery, and the starter motor, starter switch, power battery, and hand starter are all installed in the engine body. An engine starting device characterized by: 4. The rotation range in which the engine can be started is set to a low rotation of 350 rpm or less, the required capacity of the starter motor and its power battery is small, and the power battery is attached to the engine body, and the starter motor is driven by the power battery. An engine starting device characterized in that a shaft can be directly engaged and detached from a driven shaft for starting of an engine body.