JPH10141111A - Fuel injection timing detecting device for engine for model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection timing detecting device for detecting the operation timing of a fuel injection device for engine of a model. SOLUTION: A spindle 28 of an engine rotates a cam shaft 33 through gears 31, 32. An intake cam 34 and an exhaust cam 35 of the cam shaft 33 drive an intake valve and an exhaust valve through push rods 36, 37. A holder 51 having a permanent magnet 52 is fixed to one end of the cam shaft 33 projected out of a case 40 of the engine, and a Hall element 53 is arranged near. The permanent magnet 52 comes close to the Hall element 53 in this side of the fuel intake timing at about 90 degree. Driving signal is given to a fuel injection device on the basis of the advance control based on the output signal from the element 53. Since the fuel is injected at the optimal timing in response to the engine speed, starting ability, stability of low-speed rotation, and response form low-speed to high-speed or the like are improved. Operation of a model plane is thereby stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting fuel injection timing in a model engine having an electronic control type fuel injection device.

[0002]

2. Description of the Related Art In a two-cycle or four-cycle glow engine conventionally known as a model engine, a needle valve is used to control the amount of fuel supplied to a combustion chamber of the engine. An adjusting carburetor was used.

[0003]

According to the carburetor described above, when the rotation speed is suddenly increased from a low-speed rotation such as idling, a large amount of air is sucked into the valve body, while the supply of fuel is stopped. Unable to catch up, the balance of the air-fuel ratio is lost. As a result, the rotation of the engine did not rise smoothly, but did not rise smoothly, or in the worst case, the rotation of the engine stopped. In addition, the response is not good as a whole, and there is a problem that it takes time to shift from low-speed rotation to high-speed rotation or from high-speed rotation to low-speed rotation. Further, when the model engine is used by being mounted on a radio-controlled model airplane, for example, the fuel supplied to the carburetor is not properly supplied to the carburetor due to the centrifugal force and the like caused by the flight of the model airplane. In some cases, the operation of the engine became unstable.

The present inventor has invented a novel fuel injection device applied to a model engine in order to solve the above problems. The fuel injector is electronically controlled and injects fuel into the combustion chamber of the model engine. According to this fuel injection device, in a model engine under severe operating conditions, it can be expected that a stable supply of fuel to maintain a balance of air-fuel efficiency and achieve good responsiveness can be expected.

[0005] In a model engine having an electronically controlled fuel injection device, it is necessary to inject fuel at an optimal timing in order to perform efficient operation with good performance. For this purpose, means for detecting the operation stroke of the model engine is required.

In a real engine having a fuel injection device, a signal is obtained from a generator in order to determine the operation timing of a spark plug. Further, the operation timing of the fuel injection device is determined by using the signal from the generator, and the device does not necessarily have a dedicated device for obtaining a signal for controlling the fuel injection device.

[0007] The model engine has a different ignition method from the engine of the actual machine, and usually does not require an ignition device after starting in place of the spark plug, has no generator as in the engine of the actual machine, and has no generator. Timing cannot be determined using signals. Therefore, in order to use the fuel injection device in the model engine, it is necessary to provide a dedicated device for detecting the rotation state of the engine.

An object of the present invention is to provide a fuel injection timing detecting device for measuring the operation timing of a fuel injection device in order to realize a model engine provided with the fuel injection device proposed by the present inventors. I have.

[0009]

The fuel injection timing detecting device for a model engine according to the present invention is applied to a model engine having a fuel injection device, and the model engine is operated at a predetermined time during an operation stroke. Is provided.

According to a second aspect of the present invention, there is provided a fuel injection timing detecting apparatus for a model engine, wherein the detecting means includes a rotary shaft of the model engine. It is characterized by comprising a magnet provided and a sensor provided near the rotating shaft and detecting proximity of the magnet.

According to a third aspect of the present invention, there is provided a fuel injection timing detecting apparatus for a model engine according to the first aspect of the present invention, wherein the detecting means is provided on a rotating shaft of the model engine. It is characterized by comprising a light-shielding plate having a light-passing hole provided therein, and an optical sensor comprising a light-emitting element and a light-receiving element provided with the light-shielding plate interposed therebetween.

According to a fourth aspect of the present invention, there is provided the fuel injection timing detecting device for a model engine, wherein the model engine is a two-cycle engine. The means is a pressure sensor for detecting air pressure in the crank chamber of the model engine.

According to a fifth aspect of the present invention, in the fuel injection timing detecting device for a model engine, the detecting means is provided outside the case of the model engine. It is characterized by being installed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The present embodiment relates to a model engine provided with an electronically controlled fuel injection device. The model engine 1 of this example (hereinafter abbreviated as engine 1) is mounted on a radio-controlled model airplane. The engine 1 shown in FIG. 1 has four cycles, an intake valve 17 and an exhaust valve 2.
3, a piston 26 reciprocating in the cylinder 25, the crank 11 connected to the piston 26 by a connecting rod 27, and a spindle 28.

The engine 1 uses a methyl alcohol-based fuel containing a connected lubricating oil or an addition accelerator such as nitromethane. The volume of the combustion chamber is about 1 to 30 cc, and the pressure generated in the crank chamber 2 during operation pulsates in accordance with the movement of the piston of the engine 1, and the peak value of the positive pressure is generally 20 kPa to 100 kPa, and the negative pressure is Is in the range of −20 kPa to −100 kPa. Here, the positive pressure and the negative pressure are based on the average pressure in the crank chamber.

The engine 1 is controlled by a control unit 4 of a receiver 3 mounted on a radio-controlled model airplane.
When the pilot operates the transmitter 5, the receiver 3 receives radio waves from the transmitter 5 and controls each part of the model airplane including the engine 1.

The engine 1 shown in FIG. 1 is started by a starter 6. The starter 6 is driven by the electric power of the battery 8 provided through the rectifier 7 and the auxiliary air from the air cylinder 9. The control unit 4 of the radio control receiver 3 controls the switching valve 10 between the starter 6 and the air cylinder 9.

Intake manifold 13 of engine 1
Has a throttle valve 14 for adjusting the intake air amount. The opening degree of the throttle valve 14 is controlled by the driving means 15. The driving unit 15 is controlled by the control unit 4 of the radio-controlled receiver 3. Intake manifold 13
An intake air amount / temperature sensor 16 is provided in the air intake port of the first embodiment. Signals from these sensors are input to the control unit 4 of the radio control receiver 3 and used for controlling the engine 1.

A fuel injection device 30 is provided near the intake valve 17 of the intake manifold 13.
The fuel injection device 30 is supplied with pressurized fuel from the fuel tank 20. The inside of the fuel tank 20 and the crank chamber 2 are connected to each other via a check valve 24 and a regulator 21. Of the positive and negative pressures generated in the crank chamber 2, only the positive pressure is taken out by the check valve 24, Regulator 21
To make the pressure almost constant. Therefore, a substantially constant pressure is applied to the fuel in the fuel tank 20. In addition, as shown in FIG. 1, a method of connecting the air pressure of the air cylinder 9 to the regulator 21 as a pressurizing means can also pressurize the fuel tank constantly. The pressure applied to the fuel in the fuel tank 20 is substantially equal to the positive pressure of the pressure generated in the crank chamber 2 of the engine 1, and specifically, the peak value (maximum value) is about 20 kPa to 100 kPa. The fuel sent from the fuel tank 20 is supplied to the fuel injection device 30 via the filter 22.

The fuel injection device 30 includes a valve for opening and closing a fuel injection port, an urging means for urging the valve in a normally closed direction,
It has a solenoid coil that moves the valve body in the opening direction. When no drive signal is input to the solenoid coil,
The valve body closes the injection port by the urging force of the urging means,
No fuel is injected. When a drive signal is given to the solenoid coil and the solenoid moves the valve body against the urging force, the injection port is opened and pressurized fuel is injected from the injection port into the cylinder.

Referring to FIG. 2, the driving mechanism of the air supply valve 17 and the exhaust valve 23 will be described. The spindle 28 of the engine 1 rotates a poppet camshaft 33 via gears 31 and 32. In a four-cycle engine, fuel is taken (fuel injected) once for two revolutions of the engine, and the gears 31 and 32 reduce the rotation speed of the spindle 28 to half and transmit it to the poppet camshaft 33. An air supply cam 34 and an exhaust cam 35 are attached to the poppet camshaft 33 with an appropriate phase difference. The air supply cam 34 has an air supply side push rod 36 interlocked with the air supply valve 17.
The exhaust cam 35 contacts an exhaust cam 35 with an exhaust-side push rod 37 interlocking with the exhaust valve 23.

As shown in FIG. 2, the aforementioned air supply valve 1
The drive mechanism for the valve 7 and the exhaust valve 23 is housed in a case 40. The case 40 is a structure that is continuous with the wall that partitions the crankcase 2 and the cylinder 25. In this example, one end of the poppet camshaft 33 projects outward through a through hole 41 formed in the case 40. Since the through hole 41 has a seal structure, the inside and outside of the case are kept airtight enough to prevent leakage of lubricating oil.

As shown in FIG. 2, at one end of the poppet camshaft 33 protruding out of the case 40, a detecting means 5 for detecting that the engine is at a predetermined time in the operation stroke.
0 is provided. As shown in FIGS. 2 and 3, the detecting means 50 of the present example includes a disc-shaped holder 51 connected to one end of the poppet camshaft 33, a permanent magnet 52 fixed to a peripheral surface of the holder 51, It has a Hall element 53 arranged near 51.

The Hall element 53 is a sensor for detecting the magnetic field of the permanent magnet 52, and detects that the poppet camshaft 33 has reached a predetermined position in the rotation direction. Air supply valve 17
Further, since the drive timing of the exhaust valve 23 is determined by the position of the poppet camshaft 33 in which the cam is attached in the rotational direction, it is possible to detect that the engine is at a predetermined time in the operation stroke by detecting the permanent magnet.

In this example, the fuel intake timing is about 9
The permanent magnet 52 is set so as to approach the Hall element 53 just before 0 °. The detection signal output from the Hall element 53 is sent to the control unit 4 of the receiver 3 and used for determining the injection timing of the fuel injection device 30 by the advance angle control. The advance angle control is control that advances the injection timing in accordance with the degree to which the rotation speed of the engine 1 increases. Thereby, the control unit 4 can send a drive signal to the fuel injection device 30 at the most appropriate time according to the rotation speed of the engine 1.

Since the detecting means 50 of this embodiment is outside the case 40, the position where the Hall element 53 comes closest to the permanent magnet 52 can be arbitrarily changed and set. The structure for adjusting the positional relationship between the Hall element 53 and the permanent magnet 52 is arbitrary. For example, the position of the Hall element 53 may be fixed, and the position of the holder 51 in the rotation direction with respect to the poppet camshaft 33 may be changed. Further, the mounting position of the permanent magnet 52 with respect to the holder 51 may be changed, or the position of the Hall element 53 with respect to the holder 51 may be changed.

The Hall element 53 may be mounted on the outer surface of the case 40. In that case, the cylinder 25 of the engine 1 is used.
It is desirable to attach to a position as far away as possible.
It is more preferable to mount the Hall element 53 on the side of the model airplane on which the engine is mounted without making contact with the engine 1, because the influence of heat from the engine 1 can be avoided.

Next, the operation of this embodiment will be described. The model engine 1 of the present example, which is a four-cycle engine, repeats the steps of intake, compression, explosion, and exhaust, and continues to operate. Pulsating air pressure is generated in the crank chamber 2 by the reciprocating motion of the piston 26 in the cylinder 25. As for the pulsating air pressure supplied from the crank chamber 2, only the positive pressure is taken out by the check valve 24 and further taken out through the regulator 21. Join the fuel. The fuel pressurized in the fuel tank 20 is supplied to the fuel injection device 30.

According to the engine 1 of the present embodiment, the detecting means 50 detects that the engine 1 is at a predetermined time in the operation stroke, and controls the fuel injection device 30 by advancing control using the detection signal. Therefore, fuel can be injected at an optimal timing synchronized with the operation stroke of the engine 1. Therefore, startability, stability of low-speed rotation, response from low-speed to high-speed, and the like are improved. In addition, it is hardly affected by centrifugal force and acceleration in aerobatic performance, and the operation of the model airplane is stabilized.

A second example of the embodiment of the present invention will be described with reference to FIG. In this example, the structure of the detecting means is different from the above-described example. Other configurations are the same as those of the first example. The detection means 60 of this example is also provided outside the case 40 of the engine 1. The detecting means 60 includes the poppet camshaft 33
And a light sensor 62 provided with the light-shielding plate 61 interposed therebetween. The light shielding plate 61 has a light passing hole 63 formed therein. Optical sensor 6
2 has a light projecting element 64 and a light receiving element 65.

The light passing hole 63 of the light shielding plate 61 is
When it comes between the light receiving element 65 and the light receiving element 65, the light from the light projecting element 64 reaches the light receiving element 65. In this example, the light is set to pass through the light passage hole 63 of the light shielding plate 61 about 180 ° before the fuel intake timing. Thereby, the optical sensor 62
Detects that the poppet camshaft 33 has reached a predetermined position in the rotation direction, and outputs a detection signal. The advance angle control described above is performed using this detection signal. Detection means 60 of this example
Thus, it is possible to detect that the engine 1 is at a predetermined time in the operation stroke in the same manner as the detection means 50.
At the most appropriate time according to the rotational speed of the fuel injection device 3
The drive signal can be sent to 0. Further, since the detection means 60 of this example uses light, it is not affected by a magnetic field.

A third embodiment of the present invention will be described with reference to FIG. This example relates to a two-cycle model engine equipped with an electronically controlled fuel injection device. A two-cycle engine 70 does not have an intake valve or an exhaust valve unlike a four-cycle engine, and as shown in FIG. 5, an exhaust hole 71, an intake hole 72, and a scavenging hole 73 are directly formed in a cylinder, and a piston 74 Opens and closes these. The fuel injection device 30 of this example has the same configuration as that of the first example, and is mounted on the carburetor side (throttle valve 14 side) as shown in FIG. In addition, in FIG. 5, the portions functionally corresponding to FIG. 1 are denoted by the same reference numerals as in FIG. 1, and description thereof will be omitted.

The crank chamber 2 of the engine 70 is connected to the fuel tank 20 via a fuel pressurizing controller 80. In the fuel pressurization controller 80, the crank chamber 2
Is introduced. The fuel pressurization controller 80 includes an overpressure leak valve 81 that blows out pressure when the air pressure from the crank chamber 2 becomes a predetermined value or more, and an air pressure in the fuel tank 20 that flows back into the fuel pressurization controller 80. Check valve 82 for preventing the Also,
Although not shown, the fuel pressurization controller 80 has a suction valve that opens only in the direction of sucking outside air.

The fuel pressurization controller 80 is provided with a pressure sensor 85 as detecting means for detecting that the engine 70 is at a predetermined time during the operation stroke. The air pressure in the crank chamber 2 pulsates due to the reciprocating motion of the piston 74. The pressure sensor 85 detects this air pressure and outputs it as a detection signal indicating that the engine 70 is at a predetermined time in the operation stroke.

Next, the operation of this embodiment will be described. When the piston 74 descends due to the explosion of the combustion gas, the exhaust hole 71 opens first to start discharging the combustion gas, and then the scavenging hole 73 opens. The pressure in the cylinder 25 decreases, and the pressure in the crank chamber 2 increases. The air in the crank chamber 2 flows into the cylinder 25 from the opened scavenging hole 73,
The combustion gas in 5 is pushed out from the exhaust hole 71. Piston 7
When the pressure 4 starts to rise, the pressure in the crank chamber 2 becomes negative, and air starts to flow into the crank chamber 2 from the suction hole 72. When the piston 74 rises and approaches the top dead center, the piston 74 closes the exhaust hole 71 and the scavenging hole 73, the inside of the cylinder 25 becomes airtight, and the mixed gas in the cylinder 25 is compressed. When the piston 74 reaches the top dead center, the glow plug 19 ignites the mixed gas and combustion starts. This explosive force causes the piston 74 to descend and move to the exhaust stroke. In this example, since the fuel injection device 30 is mounted on the side of the throttle valve 14, it operates between the end of the suction stroke and the compression process to inject atomized fuel into the crank chamber 2.

In the above-described stroke of the engine 70, the air pressure in the crank chamber 2 rises when the piston 74 goes down, and falls when the piston 74 goes up. Therefore, pulsating air pressure is generated in the crank chamber 2. This air pressure is supplied to the fuel pressurization controller 80. The fuel pressurization controller 80 supplies a constant air pressure into the fuel tank 20 and, when the piston 74 rises, sucks outside air into the crank chamber by the suction valve.

In the present embodiment, the timing of fuel intake is when the piston 74 rises, but when the rotation of the engine 70 is fast, the injection timing is delayed. Therefore, of the signals output from the pressure sensor 85, the signal in the process of increasing the pressure indicating the lowering of the piston 74 is used by the control unit 4 for the advance angle control. That is, the signal processing in the control unit 4 delays the output of the drive signal of the fuel injection device 30 in accordance with the rotation speed of the engine 70, and causes the fuel to be injected at an appropriate timing. In this example, substantially the same effects as in the first example can be obtained.

A fourth embodiment of the present invention will be described with reference to FIG. In this example, the two-cycle engine 70 described in the third example is provided with the detection unit 50 described in the first example.
Is provided. In this embodiment, substantially the same effects as those of the above-described embodiments can be obtained.

In each of the embodiments described above, the detecting means is provided outside the engine. However, a permanent magnet is provided in the crank, and a rotational position sensor for detecting the permanent magnet is provided in the crank chamber 2. May be detected.

Each of the above-described examples can be applied to a model engine mounted on a radio-controlled model. Here, the model is not limited to a radio-controlled model airplane for hobby, but is widely used for general industrial purposes. Means a moving object equipped with an engine, and includes a model car, a model ship, and the like.

[0041]

According to the fuel injection timing detecting device for a model engine according to the present invention, the detecting means detects that the engine is at a predetermined time in the operation stroke, and utilizes the detection signal to detect the fuel injection device. Is controlled electronically,
Fuel can be injected at an optimal timing synchronized with the operation stroke of the engine. For this reason, startability, stability of low-speed rotation, response from low speed to high speed, etc. are improved,
In addition, it is hardly affected by centrifugal force and acceleration in aerobatic performance, and the rotation of the engine is stabilized, and the operation of the model airplane is stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a four-cycle engine that is a first example of an embodiment of the present invention.

FIG. 2 is a perspective view of the vicinity of a fuel injection timing detection device according to a first example of an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a fuel injection timing detection device according to a first example of an embodiment of the present invention.

FIG. 4 is a sectional view of a fuel injection timing detecting device according to a second example of the embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a two-cycle engine that is a third example of the embodiment of the present invention.

FIG. 6 is a sectional view near a fuel injection timing detection device according to a fourth example of the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 30 fuel injection device 1, 70 model engine 50, 60 detecting means 52 permanent magnet 53 Hall element as a sensor 62 optical sensor as a sensor 63 light passage hole 61 light shielding plate 64 light emitting element 65 light receiving element 85 pressure sensor as a sensor

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01B 11/26 G01B 11/26 Z

Claims (5)

[Claims] 1. A fuel injection timing detecting device for a model engine, which is applied to a model engine having a fuel injection device and includes a detecting means for detecting that the model engine is at a predetermined time in an operation stroke. 2. The apparatus according to claim 1, wherein said detecting means comprises a magnet provided on a rotating shaft of said model engine, and a sensor provided near said rotating shaft and detecting proximity of said magnet. Fuel injection timing detector for model engine. 3. The detecting means comprises: a light-shielding plate having a light passage hole provided on a rotating shaft of the model engine; and an optical sensor comprising a light-emitting element and a light-receiving element provided with the light-shielding plate interposed therebetween. The fuel injection timing detecting device for a model engine according to claim 1, wherein 4. The fuel injection timing detecting device for a model engine according to claim 1, wherein the model engine is a two-stroke engine, and the detecting means is a pressure sensor for detecting an air pressure in a crank chamber of the model engine. . 5. The fuel injection timing detecting apparatus for a model engine according to claim 1, wherein said detecting means is provided outside a case of the model engine.