JPH078830Y2 - Fuel injection device for two-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection device for a two-cylinder internal combustion engine, such as a V-type internal combustion engine, in which explosion intervals between two cylinders are unequal. .

[Prior Art] As a fuel injection device for an internal combustion engine, a fuel injection valve may be used in addition to the carburetor.

Further, as a cylinder arrangement of the internal combustion engine, there is a two-cylinder internal combustion engine such as a V-type internal combustion engine in which explosion intervals between two cylinders are unequal intervals.

Further, as a multi-cylinder internal combustion engine using the above fuel injection device, instead of providing a fuel injection valve for each cylinder, one fuel provided in a common passage portion upstream of a branch point of an intake manifold leading to each cylinder There is a method of supplying fuel to each cylinder by an injection valve (single point injection). This system minimizes the number of fuel injection valves to simplify the structure and reduce costs.

The present invention relates to a fuel injection device for a two-cylinder internal combustion engine, which uses one fuel injection valve and has explosions at non-equal intervals between cylinders.

Japanese Patent Laid-Open No. 63-154851 can be cited as a technical document disclosing this type of fuel injection device.

[Technical issues to be solved by the device]

When a single-point injection using one fuel injection valve is adopted in a two-cylinder internal combustion engine such as a V-type engine in which the explosion intervals between the two cylinders are unequal, in the prior art, both cylinders are used. Imbalance in fuel distribution due to intake inertia is likely to occur, the air-fuel ratio becomes uneven in both cylinders, and the air-fuel ratio deviates from the proper air-fuel ratio, so that sufficient performance may not be exhibited.

The above-described conventional fuel injection device for an internal combustion engine will be described below with reference to FIGS. 4 and 5.

FIG. 4 shows a configuration of a two-cylinder internal combustion engine provided with a single-point injection type fuel injection device using a single fuel injection valve and a cylinder arrangement in which explosions occur at unequal intervals, and FIG. The stroke timing of each cylinder of the internal combustion engine is shown.

In FIG. 4, a first cylinder C1 and a second cylinder C2 are arranged in a V-shape on the right and left above the crankcase 1, and each cylinder 2A, 3A and each cylinder head 2, 3 is arranged in each cylinder C1. , C2 are assembled in a V-shaped arrangement with the centerline of about 90 degrees.

In FIG. 4, reference numeral 4 denotes the center of the crankshaft, and pistons 7 and 8 of each cylinder are connected to a crankpin 4A of the crankshaft 4 via connecting rods 5 and 6.

Reference numeral 9 denotes an intake manifold, which includes branch passages 9A and 9B leading to the intake ports of the cylinders C1 and C2, and a common intake passage 10 before branching.
Inside, a single fuel injection valve 11 common to both cylinders C1 and C2 is installed.

Next, the cycle operation of the two-cylinder internal combustion engine of FIG.
It will be described with reference to the drawings.

4 and 5, when the crankshaft 4 rotates 270 degrees in the direction of the arrow after the first cylinder C1 exploded, the crankpin 4A moved from point P to point Q and the second cylinder C2 exploded. To do.

On the other hand, after this second cylinder C2 exploded, the crankshaft 4
When it rotates 90 degrees + 360 degrees = 450 degrees in the direction of the arrow, the crank pin 4A moves to point P again and the first cylinder C1 is blown up.

That is, as shown in FIG. 5, the interval θ1 from the explosion of the first cylinder C1 to the explosion of the second cylinder C2 is 270 in terms of crank rotation angle.
However, the interval θ2 from the explosion of the second cylinder C2 to the explosion of the first cylinder C1 is 450 degrees, and therefore the interval θ1 is set smaller than the interval θ2.

Therefore, after the intake of the first cylinder C1 ends, the second cylinder C2
The interval θ3 from the start of intake of the second cylinder C2 is smaller than the interval θ4 from the end of intake of the second cylinder C2 to the start of intake of the first cylinder C1.

The above-mentioned interval is the amount expressed by the rotation angle of the crankshaft 4, and N1, N2, X1, and X2 in FIG.
The lift amounts of the intake valve and the exhaust valve (not shown) of the cylinder C1 and the second cylinder C2 are shown.

As described above, in the unequal-interval ignition type internal combustion engine in which the interval θ3 from intake air to intake air is smaller than the interval θ4, the intake air introduced from the common intake passage 10 in FIG. The first cylinder is still due to the vaporized intake inertia even when the intake N1 of the cylinder C1 ends and the intake N2 of the second cylinder C2 begins
There are times when we are heading towards C1, and thus the second
The fuel filling amount of cylinder C2 becomes too small, and the intake air of the second cylinder C2
The air-fuel ratio at N2 becomes lean.

In other words, the filling amount of the first cylinder C1 becomes relatively excessive, and the air-fuel ratio in the intake air N1 of the first cylinder C1 becomes rich.

Therefore, even if the fuel injection amount is controlled so that the air-fuel ratio of one cylinder or the entire air-fuel ratio becomes appropriate, it becomes a lean or rich state when viewed for each cylinder, and it is difficult to obtain a satisfactory air-fuel ratio. there were.

Such inconvenience may occur not only in the V-type two-cylinder internal combustion engine as shown in FIG. 4 but also in the engine in which the explosion intervals between the two cylinders are unequal intervals such as the four-cycle horizontally opposed two-cylinder engine. The same can occur.

The present invention has been made in view of such a technical problem, and it is an air-fuel ratio in a cylinder of a non-equal-interval ignition type two-cylinder internal combustion engine that supplies fuel to two cylinders with one fuel injection valve. An object of the present invention is to provide a fuel injection device capable of eliminating unevenness.

[Means for solving problems]

The present invention is directed to an intake manifold in which the interval from the explosion of the first cylinder to the explosion of the second cylinder is set to be smaller than the interval from the explosion of the second cylinder to the explosion of the first cylinder, and which supplies an air-fuel mixture to these cylinders. In a fuel injection device for a two-cylinder internal combustion engine that supplies fuel to each cylinder by a single fuel injection valve provided upstream of the branch point of, the signal from the ignition coil on the second cylinder side is used as a reference, 1 per revolution of the crankshaft
An object of the present invention is to provide a fuel injection device which can reduce the unbalance of the air-fuel ratio between both cylinders and easily set the proper air-fuel ratio in any of the cylinders by performing the fuel injection once.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS.

FIG. 2 is a schematic diagram showing the configuration of a fuel injection device for an internal combustion engine suitable for implementing the present invention.

In FIG. 2, the two-cylinder internal combustion engine has two cylinders, a first cylinder C1 and a second cylinder C2, and each cylinder C1 and C2 is a cylinder.
Pistons 7 and 8 fitted in 2A and 3A bores are connected to crankpins (not shown) of crankshaft 4 via connecting lots 5 and 6, and the top surfaces of pistons 7 and 8 and the cylinder head are connected. Combustion chamber 15 of each cylinder between 2 and 3
A and 15B are formed.

In each of the combustion chambers 15A and 15B, manifolds (branch passages for intake) 9A and 9B and an exhaust passage 17 are provided through intake and exhaust ports formed in the cylinder heads 2 and 3 and opened and closed by intake and exhaust valves.
A and 17B are in communication with each other.

The upstream sides of the manifolds 9A and 9B are connected to a common intake passage 10, and the intake passage 10 is connected to the air cleaner from the upstream side.
18, a fuel injection valve 11 and a throttle valve 21 are attached.

The fuel is supplied to the fuel injection valve 11 by the fuel tank 25.
→ Filter 26 → Fuel pump 27 → Supply pipe 28 leading to the fuel injection valve 11.

A return pipe 29 for returning surplus fuel to the fuel tank 25 is connected to the supply pipe 28, and a constant fuel pressure to be supplied to the fuel injection valve 11 (a difference from the normal intake negative pressure is supplied to the return pipe 29). A pressure regulator 30 is provided to keep the pressure constant.

Reference numeral 31 in FIG. 2 denotes a battery power source.

The fuel injection valve 11 is a kind of solenoid valve, and the valve opening time, that is, the fuel injection time can be controlled by controlling the energization time, and the fuel injection amount per cycle can be controlled.

The fuel injection valve 11 is controlled by the control unit 35.

To the control unit 35, signals from various sensors for detecting an operating state of the internal combustion engine and an operation unit are input, and the fuel injection valve 11 is operated based on a result of arithmetic processing of these data by a predetermined program. Is controlled.

As the sensor and the operating unit, a rotation speed sensor 36 such as a pulsar coil for detecting the engine rotation speed, a cooling water temperature sensor 37 for detecting the engine temperature in the cooling water portion, an intake air temperature sensor 38 for detecting the intake air temperature, and a throttle. There are a throttle opening sensor 39 for detecting the opening of the valve 21, a starter switch 40 for inputting a starter on / off signal, an ignition switch 41 for inputting an ignition (operation) state on / off signal, and the like.

A control unit for controlling the fuel injection valve 11 of FIG.
Reference numeral 35 is, for example, a microcomputer system which is operated by the battery power supply 31.

FIG. 3 shows the system configuration of the control unit 35.

In FIG. 3, the CPU 60 of the control unit 35 is
It is composed of a control circuit 55 that executes arithmetic processing and the like, a ROM 56 that stores a control program and the like, and a RAM 57 that has a working area and the like.

For the CPU 60, a signal obtained by shaping the output of the rotation speed sensor 36 through a waveform shaping circuit 61, operation signals of the ignition switch 41 and the starter switch 40, and a throttle opening sensor 39, a cooling water temperature sensor 37, an intake air temperature sensor. Each sensor output from 38 and battery voltage respectively
The signal digitized by the A / D conversion circuit 63 is input to the RAM 57.

The CPU 60 calculates the valve opening time of the fuel injection valve 11 by processing the above data (input signal) based on the control program, and the fuel injection valve drive circuit 64 is operated based on the signal indicating the result. , A valve opening pulse is output. This valve opening pulse is a drive pulse that regulates the valve opening time of the fuel injection valve 11 to regulate the fuel injection amount. Therefore, in the fuel injector for a two-cylinder internal combustion engine according to the present invention, the interval from the explosion of the first cylinder C1 to the explosion of the second cylinder C2 is smaller than the interval from the explosion of the second cylinder C2 to the explosion of the first cylinder C1. Is set,
In addition, a two-cylinder that supplies fuel to each of the cylinders C1 and C2 by a single fuel injection valve 11 that is provided upstream from the branch point of the intake manifolds 9A and 9B that supplies the air-fuel mixture to these cylinders C1 and C2 In a fuel injection device for an internal combustion engine, the crankshaft 1 is set to 1 by reference to a signal from an ignition coil on the second cylinder C2 side.
It is configured to perform one fuel injection per revolution (360 degrees).

FIG. 1 is a graph showing stroke timing of each cylinder of a two-cylinder internal combustion engine equipped with a fuel injection device according to the present invention.

In FIG. 1, a 4-cycle internal combustion engine has an expansion stroke from top dead center to bottom dead center, an exhaust stroke from bottom dead center to top dead center, an intake stroke from top dead center to bottom dead center, and bottom dead center. It is operated with 4 strokes (720 degrees crank rotation) consisting of the compression stroke from to the top dead center as one cycle.

As shown in FIG. 4, the first cylinder C1 and the second cylinder C2 are 90
In the V-shaped arrangement of the degree V bank, the first cylinder C1 is operated ahead of the second cylinder C2 by θ1 = 270 degrees as shown in FIG. This is because if the first cylinder C1 is shifted by one cycle, the second cylinder C2 is 720 degrees −270 degrees = 450 degrees (= θ
It is the same as driving only 2).

In FIG. 1, X1 represents the lift amount of the exhaust valve of the first cylinder C1, N1 represents the lift amount of the intake valve of the first cylinder C1, X2 represents the lift amount of the exhaust valve of the second cylinder C2, N2 Indicates the lift amount of the intake valve of the second cylinder C2.

The angle θ4 in FIG. 1 indicates the interval from the end of intake of the second cylinder C2 to the start of intake of the first cylinder C1, and the angle θ3 is from the end of intake of the first cylinder C1 to start of intake of the second cylinder C2. And shows a relationship of θ4> θ3.

By the way, in a four-cycle engine, an ignition signal is emitted from the ignition coil at a position slightly before the top dead center (for example, 23 degrees), and it is set so that an explosion occurs just near the top dead center. It In this case, the ignition signal from the ignition coil causes the crankshaft 4 to rotate once for each cylinder (360
However, only the ignition signal (table fire) at the end of the compression stroke is used for the actual ignition and explosion.
The ignition signal (backfire) at the end of the other exhaust stroke is not used for the explosion.

Therefore, in the fuel injection device of the present invention, the interval θ1 (270 degrees) from the explosion of the first cylinder C1 to the explosion of the second cylinder C2 is from the explosion of the second cylinder C2 to the first internal combustion engine described above.
One fuel injection set on the upstream side 10 from the branch point of the intake manifolds 9A, 9B that is set smaller than the interval θ2 (450 degrees) until the explosion of the cylinder C1 and that supplies the air-fuel mixture to these cylinders C1, C2 In a two-cylinder internal combustion engine in which fuel is supplied to each cylinder C1 and C2 by the valve 11, fuel injection is performed once per one rotation of the crank spindle 4 with reference to a signal from an ignition coil on the second cylinder C2 side. Is configured.

That is, according to the present invention, the crankshaft 4 of the second cylinder C2
Fuel injection valve with the ignition signal (front fire and backfire) for each revolution of the
It is controlled to inject fuel from 11.

The timing of this fuel injection can be appropriately set within a range of, for example, about ± 30 degrees of the ignition signal (front fire and backfire).

According to such fuel injection timing, the second cylinder C2
Since the position of the ignition signal of the table fire is about 90 degrees before the start of intake N1 of the first cylinder C1, the fuel injected based on this table fire signal smoothly flows into the first cylinder C1 together with the intake N1. It was filled and a proper and stable air-fuel ratio was obtained.

Also, the ignition signal of the backfire of the second cylinder C2 is the intake air of the second cylinder C2.
Since it was approximately 23 degrees before the start of N2, the fuel injected based on this backfire signal was smoothly charged into the second cylinder C2 together with the intake N2, and an appropriate and stable air-fuel ratio was obtained.

That is, in the conventional fuel injection timing, the second cylinder C2 is in a lean mixture due to the imbalance in fuel distribution due to the intake inertia. However, in the present invention, the fuel is injected immediately before the intake port of the second cylinder C2 is opened. Since injection is performed, sufficient fuel can be supplied to the second cylinder C2, which was structurally disadvantageous, and the uneven air-fuel ratio between both cylinders C1 and C2 is suppressed, resulting in smooth and stable operation. It became possible to perform the engine operation which did.

In this way, it was possible to effectively prevent knocking on the lean side, misfire, lion, afterburn, and plug contamination on the rich side.

Further, the above-mentioned effects can be realized with a simple configuration without adding a special synchronizing system for fuel injection.

[Effect of device]

As is clear from the above description, according to the present invention, the first
The interval from the explosion of the cylinder to the explosion of the second cylinder is set smaller than the interval from the explosion of the second cylinder to the explosion of the first cylinder, and the upstream side of the branch point of the intake manifold that supplies the air-fuel mixture to these cylinders. In a fuel injection device for a two-cylinder internal combustion engine that supplies fuel to each cylinder by a single fuel injection valve provided in the engine, one fuel injection valve is used for each rotation of the crankshaft based on a signal from an ignition coil on the second cylinder side. Since the fuel injection is performed once, it is possible to inject the fuel immediately before the intake port of the second cylinder, which is thin in fuel, opens, and sufficient fuel is supplied to the second cylinder, which is structurally disadvantageous. With a simple structure, it is possible to suppress the unevenness of the air-fuel ratio between both cylinders, and it is possible to easily set both air-fuel ratios of both cylinders to appropriate values.

[Brief description of drawings]

FIG. 1 is a graph showing the stroke timing of each cylinder of a two-cylinder internal combustion engine equipped with a fuel injection device according to the present invention, and FIG. 2 shows a configuration of a fuel injection device for an internal combustion engine suitable for implementing the present invention. Fig. 3 is a block diagram of the control system of the fuel injection device of Fig. 2, and Fig. 4 is an internal combustion engine of the type in which fuel is injected by two fuel injection valves into two cylinders that explode at unequal intervals. FIG. 5 is a front view illustrating the engine, and FIG. 5 is a graph showing the stroke timing of each cylinder of the internal combustion engine of FIG. C1, C2 ... Cylinder, 4 ... Crankshaft, 9A, 9B ... Intake manifold, 10 ... Intake passage, 11 ... Fuel injection valve, 35 ...
…control unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsudai Yamakawa 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi factory (72) Inventor Hatsoe Katsune 1-1 Kawasaki-cho, Akashi-shi, Hyogo No. Kawasaki Heavy Industries Ltd., Akashi Factory

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An intake air system, wherein the interval from the explosion of the first cylinder to the explosion of the second cylinder is set smaller than the interval from the explosion of the second cylinder to the explosion of the first cylinder, and the mixture is supplied to these cylinders. In a fuel injection device of a two-cylinder internal combustion engine that supplies fuel to each cylinder by one fuel injection valve provided upstream of a branch point of a manifold, a signal from an ignition coil on the second cylinder side is used as a reference. , A fuel injection device configured to inject fuel once per one rotation of the crankshaft.