JPH03121256A - Air-fuel injection type two-cycle engine - Google Patents

Abstract

PURPOSE:To reduce dead volume and improve control accuracy by forming a holding recessed part, communicated with a fuel chamber, for fitting a fuel injection valve at the injection body of an air-fuel injection device and placing the injection nozzle of the fuel injection valve in proximity to the bottom face of the holding recessed part. CONSTITUTION:An air-fuel injection device 19 mounted at the upper part of a combustion chamber 17 formed at the lower face of a cylinder head 4 is formed of an injection body 20 as a main part, a valve mechanism 21 for switching the nozzles 26c, 26g of an air chamber 27 and a fuel chamber 28 as chambers formed in the injection body 20, and a fuel injection valve 22 mounted at the rear side part of the outer wall of the injection body 20. In this case, a holding recessed part 24a for fitting the injection valve 22 at the body 24 of the injection body 20 is provided approximately parallel to an igni tion plug (unillustrated). The bottom face of this holding recessed part 24a is communicated with the fuel chamber 28 by fuel passages 24b, 25c, as well as an injection nozzle at the tip of the fuel injection valve 22 is placed in prox imity to this bottom face.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an air-fuel injection type two-stroke engine in which air and fuel are directly injected into the cylinder by an air-fuel injection device, and in particular, the present invention relates to an air-fuel injection type two-stroke engine in which air and fuel are directly injected into the cylinder by an air-fuel injection device. Control accuracy of injection amount and injection response for each cycle when fuel is supplied by an injection valve and fuel is injected into the combustion chamber by opening and closing the injection port on the combustion chamber side of the fuel chamber with a valve. Concerning sexual improvement.

[Conventional technology]

Two-stroke engines are advantageous in that they are small and lightweight, and can provide high output with a compact structure, but they are prone to irregular combustion, including misfires, at low speeds and low loads, and their exhaust gas contains a large amount of hydrocarbons. Additionally, there are structural problems such as poor fuel consumption due to blow-through caused by the scavenging system. Air-fuel injection two-stroke engines have recently been attracting attention as two-stroke engines that are expected to solve these problems.

As an air-fuel injection device employed in the above-mentioned two-cycle engine, the inventors of the present application have proposed an injection body in which an air chamber and a fuel chamber are formed, each having an injection port into a combustion chamber, and an injection port in the air chamber and fuel chamber. We have developed a system that consists of a valve mechanism that opens and closes the fuel chamber using a valve, and a fuel injection valve that supplies fuel to the fuel chamber in synchronization with the opening timing of the valve. The fuel injection valve is held by the housing by fitting and inserting its injection nozzle side end into the holding recess of the housing, and the holding recess is communicated with the fuel chamber through a fuel passage.

Here, as the fuel injection valve, it is conceivable to use a fuel injection valve installed toward the intake valve in a four-cycle engine. FIG. 6 is a sectional view showing a state in which a fuel injection valve having a structure similar to that conventionally adopted for four-cycle engines is attached to an injection body. In FIG. An injection nozzle 82a formed at the tip of the vibrator 83a is opened and closed by a valve 83 having a sphere 83b fixed to the tip of the vibrator 83a. Further, a cylindrical guide vibe 85 is fixed to the injection nozzle 823 portion. The guide vibe 85 is for regulating the injection direction, injection range, etc. The fuel injection valve 81 is assembled by fitting and inserting the tip of the valve body 82 into a holding recess 84a formed in the injection body 84.
It is held at 4. Note that 84b is the holding recess 84.
86 is a buffer member for preventing engine vibrations from being directly transmitted to the fuel injection valve 81, and 87 is a seal ring.

In the above-mentioned air fuel injection device, the fuel injection valve 81 is turned on in accordance with the opening timing of the valve on the fuel chamber side, so that the fuel filling the fuel chamber is injected by the amount of fuel injected from the fuel injection valve 81. The air is injected into the combustion chamber from the opening, and at the same time compressed air in the air chamber is injected from the air injection port.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned air fuel injection device, the injected fuel from the fuel injection valve 81 is not directly injected into the combustion chamber, but the fuel filled in the fuel chamber is pushed out by the above-mentioned amount of injected fuel, so that the fuel is injected into the combustion chamber. be done. Therefore, in order to more accurately control the amount of injection into the combustion chamber for each cycle and improve responsiveness, it is necessary to reduce the amount of fuel stored in the fuel chamber, etc., so-called dead volume, as much as possible. is requested.

However, in the case of the fuel injection valve 81 shown in FIG. 6, the interior space of the guide pipe 85 that regulates the injection direction, etc., also becomes the dead volume described above, and cannot meet the above requirements.

The present invention has been made in view of the above-mentioned demands, and is an air-fuel injection type 2 that can improve the control accuracy and responsiveness of the injection amount for each cycle by reducing the dead polyneum.
The purpose is to provide cycle engines.

[Means for solving problems]

Therefore, the present invention provides an air-fuel injection type two-stroke engine in which air and fuel are directly injected into the cylinder by an air-fuel injection device, and the air-fuel injection device has an injection port into the combustion chamber, and the air-fuel injection device and an injection body formed with a chamber in which fuel is supplied alone or in a mixed state;
It is composed of a valve mechanism that opens and closes the injection port by a valve, and a fuel injection valve that supplies fuel to the chamber, and a holding recess for holding the fuel injection valve is formed in the injection body, and a bottom surface of the holding recess and a fuel injection valve are formed. The fuel injection valve is characterized in that a fuel passage communicating with the chamber is formed, and an injection nozzle of the fuel injection valve is placed close to the bottom surface of the fuel passage.

Here, placing the injection nozzle of the fuel injection valve close to the bottom surface of the holding recess means that there is no space between the injection nozzle and the bottom surface, which becomes the above-mentioned dead volume. From this point of view, it is desirable to have the end surface on the injection nozzle side contact the bottom surface, but in practice, from the viewpoint of protecting the fuel injector, a gap should be provided to the extent that engine vibrations are not directly transmitted to the fuel injector. .

Further, the present invention provides a device of a type that has separate air chambers and fuel chambers as the chambers and mixes air and fuel during injection into the combustion chamber, and the chambers are shared.
It can be applied to any type of device in which air and fuel are supplied in a mixed state.

[Effect]

In the air fuel injection device according to the present invention, since almost no space is formed between the end face on the injection nozzle side of the fuel injection valve and the bottom face, the dead volume is reduced by the volume needle of the sixth guide vibe 85. be done. As a result, control accuracy of the amount of fuel to be injected in each cycle and injection responsiveness are significantly improved.

Here, in the present invention, since the guide vibe 85 is not provided, it is not possible to regulate the injection direction and the injection head area.
This does not have any negative effects; in other words, the present invention does not inject fuel into the intake pipe or directly inject fuel from an injection valve into the combustion chamber, but instead fills the fuel chamber as the chamber. Since the structure is such that the fuel injected into the combustion chamber is injected by pushing out the fuel, there is no need to restrict the direction of injection by the fuel injection valve, and the above-mentioned adverse effects do not occur.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are diagrams for explaining an air-fuel injection type two-stroke engine according to an embodiment of the present invention,
Figure 1 is a cross-sectional side view showing the fuel injection valve in its holding state;
3 are a cross-sectional side view and a cross-sectional front view of the air-fuel injection device alone, respectively, and FIGS. 4 and 5 are a cross-sectional right side view of the engine of this embodiment.

It is a front view.

In the figure, reference numeral 1 denotes a water-cooled two-stroke parallel three-cylinder engine configured to directly inject air and fuel into the cylinders. Cylinder bodies 3 formed in parallel are mounted and fixed with bolts, and a cylinder head 4 is arranged on the cylinder bodies 3 and fixed with bolts.

A piston 5 slidably inserted into each cylinder 3a is connected to a crank arm 6a of a crankshaft 6 disposed in the crankcase 2 via a connecting rod 6b. It is located within the crank chamber 2a of the crankcase 2. In addition, an intake port 2b for introducing outside air is formed on the back side of each crank chamber 2a located on the rear side (left side in FIG. 4) when mounted on the vehicle.
Each intake port 2b is provided with a closed valve 7 for opening and closing the intake port 2b. The above-mentioned intake ports may be formed on the front side of the crank chamber 2a, and branch pipes 8a of the intake manifold 8 are connected to each of the above-mentioned intake ports 2b, and an air chamber where the branch pipes 8a join together is formed. 8b extends substantially parallel to the crankshaft 6 on the back surface of the cylinder body 3. Furthermore, a throttle body 9 containing a throttle valve is connected to one end of the air chamber 8b.
Although not shown, the throttle body 9 is connected to an air cleaner via an air duct.

In addition, 12 is an auxiliary fuel injection valve that injects fuel to the upstream side of the throttle valve when the opening degree is a predetermined opening or more.
3 is a 5-meter meter that detects the opening of the throttle valve, and 4 is a meter that detects the opening of the throttle valve. 1. Item 5 is a pulley for driving various auxiliary equipment.

Furthermore, an exhaust port) 3b is formed above the intake port 2b on the rear side of the cylinder body 3, and each branch pipe of the exhaust manifold 16 connected to each exhaust port) 3b is connected to the air chamber 8b. After merging near the top, it bends downward and extends toward the rear of the vehicle. Although not shown, scavenging passages are formed in the cylinder body 3 to communicate the crank chambers 2a with the upper portions of the cylinders 3a.

Further, a hemispherical combustion recess 4a, which forms a combustion chamber 17 with a recess 5a recessed in the upper surface of the piston 5, is formed in a portion of the lower surface of the cylinder head 4 facing each cylinder 3a. There is. Into each combustion chamber 17 is inserted an electrode portion 18a of a spark plug 18 that is screwed into the cylinder head 4 from diagonally rearward.

Furthermore, each combustion chamber 17 on the upper surface of the cylinder head 4
Each air-fuel injection device 19 is installed in the upper part, and each air-fuel injection device 19 mainly includes an injection body 20 inserted and fixed into the cylinder head 4, and an injection body 20 formed within the injection body 20. a pulp mechanism 21 that opens and closes an air chamber as a chamber and an injection port of a fuel chamber;
The fuel injection valve 22 is attached to the rear portion of the outer wall of the injection body 20 and supplies fuel to the fuel chamber.

The injection body 20 includes a combustion chamber 17 of the cylinder rad 4.
The housing 23 inserted into the mounting hole 4b facing the
The boar housing 23 is pressed and fixed onto the cylinder head 4, and the valve mechanism 21 and the fuel injection valve 22 are
It consists of a main body 24 that holds the.

The housing 23 has an outer housing 25 formed by integrally forming a flange portion 25b on the upper end of a cylindrical body portion 25a.
A flange portion 26 is attached to the upper end of the cylindrical body portion 26a.
The flange portion 25b of the outer housing 25 is pressed and fixed onto the cylinder head 4 by the body main body 24.

Here, the inside of the hole passing through the axis of the inner housing 26 is an air chamber 27, and the lower end opening of the through hole is an air injection port 26c facing the combustion chamber 17. Further, upper and lower horizontal grooves 26d and 26e are formed in the upper and lower parts of the outer peripheral surface of the inner housing 26 in a ring shape, and upper and lower horizontal grooves 26d and 26e are formed in the outer peripheral surface of the inner housing 26. They are communicated by a pair of vertical grooves 26f formed to extend in the axial direction. A fuel chamber 28 is formed inside each of the horizontal grooves 26d and 26e and the vertical groove 26, and the fuel chamber 28 has a fuel injection port 26g formed at the lower end of the inner housing 26.
It communicates with the inside of the combustion chamber 17 by. Note that 30 is a seal ring.

Furthermore, the pulp 33 that constitutes the above-mentioned valve mechanism 21 is inserted into the through hole of the inner housing 26 from below. This pulp 33 is integrally formed with a vertical valve plate 33b at the lower end of a valve shaft 33a, and the air injection port 26C and the fuel injection port 26g are opened and closed by this valve plate 33b. Further, the valve shaft 33a has guide pieces 3 at two locations, upper and lower.
3d.

336 is integrally formed, and the guide piece comes into sliding contact with the inner circumferential surface of the inner housing 26. In addition, the valve shaft 33a
protrudes from the upper surface of the main body 24, and the protrusion 33e
A disk-shaped retainer 34 is screwed onto the locknaft 3.
It is fixed at 5.

Further, a cap 43 is removably disposed on the upper end surface of the main body 24 so as to surround the retainer 34, and the outer circumferential surface of the retainer 34 is in sliding contact with the inner circumferential surface of the cap 43. Further, an electromagnetic coil 36 is embedded in the lower portion of the retainer 34 of the main body 24, which is excited when energized and attracts the retainer 34 downward. Further, a cylindrical spring seat 37 is screwed into the axis of the electromagnetic coil 36 so that its vertical position can be changed, and the pulp 33 is attached between the spring seat 37 and the retainer 34 in the closing direction. A biasing spring 38 is provided. Note that 39 is a set bolt for fixing the spring seat in a predetermined position.

Furthermore, the body main body 24 has an air inlet 24d.
is formed, and the introduction port 24d is connected to the inner housing 2 through a communication hole 37a formed in the spring seat 37.
It communicates with an air chamber 27 in 6. Further, each of the air fuel injection devices 19 is connected to each other by an air rail 40,
The air passage 40a formed through the air rail 40 is
The branch passage 40b communicates with the air inlet 24d of the 24 body bodies. Note that 42 is a plug that closes the hole machined when forming the branch passage 40b, and although not shown, one end of the air passage 40a is connected to a compressed air source, and the other end is connected to a pressure regulating valve.

Further, a holding recess 24a is recessed above the spark plug 18 in a portion of each body main body 24 located on the rear side when mounted on the vehicle, and is recessed approximately parallel to the spark plug 1 for mounting the fuel injection valve 22 thereon. Inside each holding recess 24a, the main body 24. Flange portion 2 of the outer housing 25
5b, the fuel passage 24b is formed to extend diagonally downward.
, 25C, the horizontal groove 26d on the upper side of the fuel chamber 28
is connected to.

An end of the fuel injection valve 22 on the injection nozzle side is inserted and held in each of the holding recesses 24a. The fuel injection valve 22
The injection port 5 is mainly composed of a valve body 51 having an injection nozzle 51a formed at its tip, and a spherical opening/closing ball 52b fixed to the tip of a cylindrical operating pipe 52a.
Valve 52 that opens and closes 1a and drives the valve 52! It is composed of a magnetic coil 53. Note that 54 is a biasing spring that biases the valve 52 in the closing direction, 51b is a connection portion of a wire harness that supplies power to the electromagnetic coil 53,
54 is a fuel filter.

A rubber buffer ring 29 is interposed between the end of each fuel injection valve 22 on the injection nozzle 51a side and the bottom surface 24c of the holding recess 24a. A slight gap is provided between 22a and the bottom surface 24e. This gap and the buffer ring 2
9 is for preventing vibrations on the engine side from directly affecting the fuel injection valve 22.

Further, the fuel supply port 22b at the upper end of each of the fuel injection valves 22 is inserted into one fuel rail 31,
It communicates with the fuel passage 31a in 1. This fuel rail 31 is an aluminum alloy die-cast product with a length spanning the arrangement width of the three fuel injection valves 22, and is bolted and fixed to the upper surface of the cylinder head 4 by a stay 32.

In this way, the fuel injection valves 22 are connected to each other by the fuel rail 31 to form a unit, and the holding recess 24 is connected to the body main body 24.
Since a buffer ring 29 is interposed within a, it is elastically supported.

Next, the effects of this embodiment will be explained.

In the engine 1 of this embodiment, as the piston 5 moves upward, the pressure inside the crank chamber 2a becomes negative. The intake valve 7 opens to introduce outside air, and as the piston 5 moves downward, the crank chamber 2a becomes negative pressure.
As the air in the cylinder 3a is primarily compressed, the exhaust port 3b opens, and a little later the scavenging boat opens, thereby supplying fresh air from the scavenging boat into the cylinder 3a and exhausting combustion gas from the exhaust port. be done. At this time, compressed air at a predetermined pressure is supplied into the air chamber 27 of each air-fuel injection device 19 via the air passage 40a of the air rail 40, and fuel at a predetermined pressure is supplied to the fuel injection valve 22. It is supplied via rail 31. Then, the electromagnetic coil 36 of each air-fuel injection device 19 is energized in accordance with the opening timing of the exhaust valve 3b, and the valve 33 is thereby lowered to open the air injection port 26C and the fuel injection port 2.
6g is opened and the compressed air in the air chamber 27 enters the air injection port 26.
C is injected into the combustion chamber 17. Also, the electromagnetic coil 36
At the same time, the electromagnetic coil 53 of the fuel injection valve 22 is also energized, causing the valve 52 to rise and the injection nozzle Sta to open, injecting fuel from the fuel rail 31, and as a result, the inside of the fuel chamber 28 is The fuel stored in the fuel injection valve 26 is injected into the combustion chamber 17 from the fuel injection port 26g in an amount corresponding to the amount of fuel injected from the fuel injection valve 22.

In this manner, in the present embodiment, the fuel in the fuel chamber 28 is pushed out by the fuel injected from the fuel injection valve 22 and injected into the combustion chamber 17. In this case, the smaller the stored amount of fuel (dead volume), the more accurately the injection amount from the fuel injection valve 22 and the injection amount actually injected into the combustion chamber match, and the responsiveness improves. Therefore, as described above, reduction of dead volume is required. In this embodiment, the tip surface 22 of the fuel injector 22 is
1 and the bottom surface 24C of the holding recess 24a, the dead volume can be reduced by the space created by the guide vibe 85 compared to the case shown in FIG. As a result, control accuracy and responsiveness of the amount of fuel injected per cycle can be improved.

In the above embodiment, the chamber is an air chamber.

Although a type of air-fuel injection device having separate fuel chambers has been described as an example, the present invention can also be applied to a type of device in which an air chamber and a fuel chamber are shared.

〔Effect of the invention〕

As described above, according to the air-fuel injection type two-cycle engine according to the present invention, since the tip surface of the fuel injection valve is brought close to the bottom surface of the holding recess, the dead volume can be reduced accordingly, and the control accuracy of the amount of injected fuel can be reduced accordingly. and has the effect of improving responsiveness.

[Brief explanation of drawings]

1 to 5 are diagrams for explaining an air-fuel injection type two-stroke engine according to an embodiment of the present invention,
Figure 1 is a cross-sectional side view showing the fuel injection valve in its holding state;
Figure 3 is a cross-sectional side view of the air fuel injection device, respectively.
4 is a sectional front view. FIG. 5 is a sectional right side view and front view of the engine of this embodiment, and FIG. 6 is a partially sectional side view for explaining the problem to be solved by the invention. In the figure, 1 is an air-fuel injection two-stroke engine;
3a is a cylinder, 17 is a combustion chamber, 19 is an air fuel injection device,
20 is a housing, 21 is a valve mechanism, 22 is a fuel injection valve, 24a is a holding recess, 24b and 25c are fuel passages, 2
4C is the bottom, 260° 26g is the injection port, 27 is the air chamber,
28 is a fuel chamber, 33 is a valve, and 51a is an injection port of a fuel injection valve.

Claims (1)

[Claims] (1) In an air-fuel injection type two-cycle engine in which air and fuel are directly injected into the cylinder by an air-fuel injection device, the air-fuel injection device has an injection port into the combustion chamber, and the air and fuel are injected directly into the cylinder. The injection body includes a chamber in which fuel is supplied alone or in a mixed state, a valve mechanism that opens and closes the injection port with a valve, and a fuel injection valve that supplies fuel to the chamber. A holding recess for holding the fuel injection valve is formed, a fuel passage is formed that communicates a bottom surface of the holding recess with the chamber, and an injection nozzle of the fuel injection valve is brought close to the bottom surface. Air-fuel injection type 2-stroke engine.