JP2741754B2 - Valve guide structure of air fuel injection type 2 cycle engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel injection type two-stroke engine in which air and fuel are directly injected into a cylinder by an air-fuel injection device, and in particular, to a lateral swing of a valve. The present invention relates to a structure capable of improving the responsiveness by reducing the weight while avoiding a decrease in the sealing property of the valve seat portion due to the above.

[Conventional technology]

The two-stroke engine is advantageous in that it is compact and lightweight, and can provide high output with a simple structure. However, irregular combustion including misfire easily occurs at low speed and low load, and the exhaust gas contains a large amount of hydrocarbons. In addition, there are structural problems such as a low fuel consumption rate due to blow-by caused by the scavenging method.
The air fuel injection type two-stroke engine has recently attracted attention as a two-stroke engine expected to solve such problems.

As an air fuel injection device used in this engine,
Conventionally, this is described, for example, in Japanese Patent Application Publication No. Sho 61-503043. This is configured such that a fuel duct and a compressed air duct are connected to a chamber that opens toward the combustion chamber, a valve is disposed in the chamber, and the valve is moved by an electromagnetic coil to open and close the opening. As a guide structure of this valve, a cylindrical guide portion having a structure similar to that of a conventional four-stroke engine is provided on the housing side, and a valve shaft is inserted into the guide portion to guide the valve. Can be considered.

By the way, when the valve is driven by an electromagnetic coil as in the air fuel injection device, it is necessary to reduce the weight of the valve in order to improve responsiveness during high-speed operation. It is trying to become.

[Problems to be solved by the invention]

However, if the valve shaft is made too small,
There is a problem that the valve easily swings laterally, and in some cases, the sealing property of the valve seat portion is reduced. To avoid this problem, it is effective to make the cylindrical guide portion longer in the axial direction. However, it is difficult to process such a small-diameter and long hole, and the productivity tends to decrease.

The present invention has been made in view of the above-described conventional circumstances, and it is possible to improve the responsiveness by reducing the diameter of a valve shaft while preventing a decrease in sealing performance due to lateral runout of a valve, and also to reduce productivity. It is an object of the present invention to provide a valve guide structure for a two-stroke engine without air fuel injection.

[Means for solving the problem]

Therefore, the present invention forms a chamber in which air and fuel are supplied alone or in a mixture in a housing inserted into a cylinder head and opens the chamber toward a combustion chamber,
An air fuel injection type two-stroke engine in which a valve for opening and closing the opening is inserted into the chamber, and a retainer fixed to an end of a valve shaft of the valve is sucked by an electromagnetic coil to open and close the opening. In the structure for guiding the valve so as to be slidable in the axial direction, a guide surface that slides on an outer peripheral surface of the retainer is formed on a cap or a housing that covers the retainer.

[Action]

According to the valve guide structure of the air-fuel injection type two-stroke engine according to the present invention, the guide surface is formed on the cap or the housing, and the outer peripheral surface of the retainer fixed to the valve stem of the valve is slidably contacted with the guide surface. Therefore, the movement of the valve in the direction perpendicular to the valve shaft can be restricted without hindering the movement of the valve in the valve shaft direction. The responsiveness at the time of high-speed operation can be improved by reducing the weight of the valve while avoiding deterioration of the performance.

In addition, since the retainer is guided by the cap or the housing, the structure is simple, and the productivity does not decrease as in the case where the guide portion including the elongated guide hole is further lengthened.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 6 are views for explaining an air fuel injection type two-stroke engine according to one embodiment of the present invention. FIGS. 1 and 4 are sectional views of an air fuel injection device, and FIGS. The figure shows the cap alone, FIG. 3 shows the retainer alone, and FIGS. 5 and 6 are a cross-sectional side view and a front view of the engine.

In the figure, reference numeral 1 denotes a water-cooled two-cycle parallel three-cylinder engine configured to inject air and fuel directly into a cylinder.
One cylinder 3a is mounted with a cylinder body 3 formed in parallel in the crankshaft direction and fixed by bolting, and a cylinder head 4 is arranged on the cylinder body 3 and fixed by bolting.

Piston 5 slidably inserted into each cylinder 3a
Is a crankshaft 6 disposed in the crankcase 2.
Are connected via a connecting rod 6b to each of the crank arms 6a.
Located in the crank chamber 2a. In addition, each crankcase 2a
At the rear of the vehicle (on the left side in FIG. 6), intake ports 2b for introducing outside air are formed, and each intake port 2b is provided with a reed valve 7 for opening and closing the intake ports. Have been.
Note that the intake port 2b may be formed on the front side. Further, a branch pipe 8a of the intake manifold 8 is connected to the intake port 2b, and a throttle body 9 having a built-in throttle valve is connected to one end of an air chamber 8b where the respective branch pipes 8a join. Although not shown, the throttle body 9 is connected to an air cleaner via an air duct. Reference numeral 12 denotes an auxiliary fuel injection valve that injects fuel upstream of the throttle valve when the throttle valve has a predetermined opening degree or more, 13 a potentiometer that detects the opening degree of the throttle valve, 14 a generator, and 15 various types. It is an accessory drive pulley.

Further, the intake port 2b on the rear side of the cylinder body 3
An exhaust port 3b is formed in the upper part, and the exhaust manifold 16 connected to each of the exhaust ports 3b is bent downward after the branch pipes join near the upper part of the air chamber 8b, and are bent downward and toward the rear of the vehicle. Extending. Although not shown, a scavenging passage is formed in the cylinder body 3 to communicate the crank chambers 2a with the upper portions of the cylinders 3a.

Further, in a portion of the lower surface of the cylinder head 4 facing each of the cylinders 3b, a combustion concave portion 4a constituting a combustion chamber 17 by a concave portion 5a concavely formed on an upper surface of the piston 5 is formed in a hemispherical shape. I have. In each of the combustion chambers 17, an electrode portion 18a of an ignition plug 18, which is screwed into the cylinder head 4 obliquely from behind, is inserted.

Further, an air fuel injection device 19 is mounted on an upper portion of each combustion chamber 17 on the upper surface of the cylinder head 4. Each of the air fuel injection devices 19 mainly includes an injection body 20 inserted and fixed to the cylinder head 4, a valve mechanism 21 for opening and closing an injection port of an air chamber and a combustion chamber formed in the injection body 20, A fuel injection valve 22 is mounted on the rear portion of the outer wall of the injection body 20 and supplies fuel to the fuel chamber.

The injection body 20 has a housing 23 inserted into a mounting hole 4b facing the combustion chamber 17 of the cylinder head 4, and presses and fixes the housing 23 on the cylinder head 4.
It comprises the valve mechanism 21 and a body main body 24 holding the fuel injection valve 22.

Above the spark plug 18 at a portion of the body main body 24 located on the rear side when mounted on the vehicle, a mounting concave portion 24a for mounting the fuel injection valve 22 is recessed substantially in parallel with the spark plug 18. The body 24 has a bottom 24c of each mounting recess 24a.
A fuel supply hole 24b that extends obliquely downward from is formed. Further, the injection port side end of the fuel injection valve 22 is inserted into each mounting recess 24a, and the front end surface 22a of the injection valve 22 faces the bottom surface 24c with a slight gap therebetween, and A cushioning member 29 is interposed between and the bottom surface 24c.

Further, a fuel supply port 22b at the upper end of each of the fuel injection valves 22 is provided.
Is inserted into one fuel rail 31, and the rail 31
It communicates with the fuel passage 31a. The fuel rail 31 is an aluminum alloy die-cast product having a length corresponding to the arrangement width of the three fuel injection valves 22, and is fixed to the upper surface of the cylinder head 4 by bolts with a stay 32. In this manner, the fuel injection valves 22 are connected to each other by the fuel rail 31 to form a unit, and with respect to the body main body 24, the buffer member 2 is provided in the mounting recess 24a.
9 is elastically supported by the interposition.

An air inlet 24d is formed in the front side of the body 24, and an air rail 40 is provided in the inlet 24d so as to cover the air inlet 24d. The air rail 40 is made of an aluminum alloy drawing material having a length that is equal to the width of the three air fuel injection devices 19 and supplies compressed air to each of the injection devices 19. It also functions as a stay connected to each other as a unit.
That is, each injection device 19 is fixed to this air rail by a fixing bolt.
An air passage 40a fixed to the air passage 40 and formed through the air rail 40 is connected to the air introduction port by a branch passage 40b.
Communicates with 24d. Reference numeral 42 denotes a plug for closing a processing hole when the branch passage 40b is formed.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. Thus, the inside of the air passage 40a is adjusted to a predetermined air pressure.

The housing 23 has an inner housing 26 formed by integrally forming a flange portion 26b at an upper end of a cylindrical body portion 26a inside an outer housing 25 having a flange portion 25b integrally formed at the upper end of a cylindrical body portion 25a. Of the outer housing 25 is pressed onto the cylinder head 4 by the body main body 24.

The inside of the through hole in the axial direction of the inner housing 26 is an air passage.
The lower end opening of the air passage 27 is an air injection port 26c facing the combustion chamber 17. Further, upper and lower lateral grooves 26 are provided on the upper and lower portions of the outer peripheral surface of the inner housing 26.
d and 26e are recessed in a ring shape, and the upper and lower lateral grooves 26
The d and 26e are connected to each other by a pair of longitudinal grooves 26f formed to extend in the axial direction on the outer peripheral surface. Each of these lateral grooves 26
A fuel passage 28 is formed in the insides d and 26e and the vertical groove 26f. The fuel passage 28 communicates with the inside of the combustion chamber 17 by a fuel injection port 26g formed at a lower end of the inner housing 26. The upper lateral concave groove 26d communicates with a fuel supply hole 24b of the body main body 24 via a fuel supply hole 25c formed in the outer housing 25. In addition, 30 is a ceiling.

A valve 33 constituting the above-described valve mechanism 21 is inserted into the air passage 27 of the inner housing 26 from below. The valve 22 is formed integrally with a mushroom-shaped valve plate portion 33b at the lower end of a valve shaft portion 33a. The valve plate portion 33b opens and closes the air injection port 26c and the fuel injection port 26g. Guide protrusions 33d and 33e are integrally formed at two positions above and below the valve shaft portion 33a in the axial direction, respectively.
The outer end surfaces of d and 33e are in sliding contact with the inner peripheral surface of the air passage 27.

The upper portion of the valve shaft 33a of the valve 33 protrudes from the upper surface of the body 24, and a retainer 34 is screwed into the protruding portion 33c and fixed with a lock nut 35. The retainer 34 has a disk shape made of a magnetic material, and has a screw hole 34c formed at the center thereof and tool holes 34b formed at both sides thereof. The outer peripheral surface of the retainer 34 is finished with roundness and smoothness which do not hinder sliding with a cap described later, thereby forming a guide surface 34a. The body 24
A magnetic coil 36 that is excited when energized and attracts the retainer 34 downward is embedded in a lower portion of the retainer 34.
A cylindrical spring seat 37 is variably screwed up and down on the axis of the electromagnetic coil 36, and the valve 33 is biased between the spring seat 37 and the retainer 34 in the closing direction. Spring 38
Is interposed. Further, the spring seat 37 has a communication hole 37a.
The air inlet 24d of the body 24 and the air passage 27 of the inner housing 26 are formed through the communication hole 37a.
The inside of the air passage 27 has the same air pressure as the inside of the air passage 40a. Reference numeral 39 denotes a set bolt for fixing the spring seat 37 at a predetermined position.

A rectangular plate-like cap 43 that covers the retainer 34 is detachably mounted on the upper end surface of the body main body 24, and the cap 43 is positioned by the knock pin 45, and then fixed by the bolt 44a. I have. Above cap 43
A circular concave portion 43a surrounding the retainer 34 is formed in the lower surface of the cover. A guide surface 43b is formed on the inner peripheral surface of the concave portion 43a by finishing, and the outer peripheral surface 34a of the retainer 34 is in sliding contact with the guide surface 43b. Thereby, the movement of the retainer 34 in the direction perpendicular to the axis is prevented, and the movement in the axial direction is free.

 Next, the operation and effect of this embodiment will be described.

In the engine 1 of this embodiment, when the pressure in the crank chamber 2a becomes negative as the piston 5 rises, the reed valve 7 opens to introduce outside air, and as the piston 5 descends, the air in the crank chamber 2a is primarily compressed. At the same time, the exhaust port 3b opens, and the scavenging port opens a little later, whereby fresh air is supplied into the cylinder 3a from the scavenging port, and the combustion gas is exhausted from the exhaust port 3b. At this time, compressed air of a predetermined pressure is supplied to the air passage 27 of each air fuel injection device 19 through the air passage 40a of the air rail 40, and fuel of a predetermined pressure is supplied to the fuel injection valve 22 by fuel. It is supplied via a rail 31. And the above exhaust port
The electromagnetic coil 36 of each air fuel injection device 19 is energized in accordance with the opening timing of 3b, and almost simultaneously with this, the fuel injection valve
22 turns on. As a result, the valve 33 descends to open the air injection port 26c and the fuel injection port 26g, and the compressed air in the air passage 27 flows from the air injection port 26c, and the fuel from the fuel injection valve 22 flows from the fuel injection port 26g to the combustion chamber. It is injected into 17.

In such opening and closing operation of the valve 33, the valve 33
The valve stem 33a of the lower half has guide projections 33d and 33e.
Is in sliding contact with the air passage 27, and the guide surface 34a of the retainer 34 fixed to the protrusion 33c at the upper end thereof is in sliding contact with the guide surface 43b of the cap 43. As a result, the retainer 34 and thus the projection 33c of the valve shaft 33a are movable in the axial direction and are restricted from moving in the direction perpendicular to the axis.

Thus, according to the present embodiment, the guide surface of the cap 43
Since the guide surface 34a of the retainer 34 is slidably contacted with the 43b to restrict the movement in the direction perpendicular to the axis, even if the diameter of the valve shaft 33a of the valve 33 is reduced, no lateral run-out occurs. The responsiveness during high-speed operation can be improved while reducing the weight while avoiding the collision. Moreover, in this embodiment, the retainer 34 is
It is a simple structure that only slides in contact with it, making it easier to manufacture than when the above-described processing of the elongated guide hole is required,
There is no decrease in productivity.

In the present embodiment, the upper and lower guide projections 33d and 33e are formed on the valve stem 33a and are slidably contacted with the inner peripheral surface of the air passage 27. be able to.

In the above embodiment, the guide surface 43b is formed on the cap 43, and the guide surface 34a of the retainer 34 is slidably contacted with the guide surface 43b.
As the sliding contact structure 34, a modified example shown in FIG. 7 can be adopted. In this example, the cap mounting portion 46 of the body 24 is extended to form a guide surface 46a on the inner peripheral surface of the mounting portion 46, and the guide surface 34a of the retainer 34 is brought into sliding contact with the guide surface 46a. In the case of this modification, the same effect as in the above embodiment can be obtained.

〔The invention's effect〕

As described above, according to the valve guide structure of the air-fuel injection type two-cycle engine according to the present invention, the guide portion is formed in the cap or the cap mounting portion of the housing, and the guide portion is fixed to the valve shaft portion of the valve. Since the retainer is slid in contact with the valve, it is possible to prevent lateral run-out without hindering the opening and closing operation of the valve, and as a result, it is possible to reduce the weight of the valve without deteriorating the sealing performance and improve the responsiveness.

[Brief description of the drawings]

1 to 6 are views for explaining a valve guide structure of an air fuel injection type two-stroke engine according to one embodiment of the present invention. FIG. 1 is a sectional view showing the valve guide structure, and FIG. (A) and (b) are a plan view and a sectional view of a cap, respectively, and FIGS. 3 (a) and (b) are a plan view and a sectional view of a retainer, respectively. FIG. 4 is a sectional view showing an air fuel injection device. 5 and 6 are a right side view and a front view, respectively, of a cross section of the engine of the embodiment, and FIG. 7 is a cross section showing a modification of the above embodiment. In the figure, 1 is an air fuel injection type two-stroke engine,
3a is a cylinder, 4 is a cylinder head, 17 is a combustion chamber, 23 is a housing, 27 is an air passage (chamber), 28 is a fuel passage, 33
Is a valve, 33a is a valve shaft portion, 33b is a valve plate portion, 34 is a retainer,
Reference numeral 34a denotes a guide surface (outer peripheral surface of the retainer), 36 denotes an electromagnetic coil, 43 denotes a cap, 43b and 46a denote guide surfaces (guide portions of a cap and a cap mounting portion), and 46 denotes a cap mounting portion.

Claims (1)

(57) [Claims] 1. A chamber in which air and fuel are supplied alone or in a mixed state is formed in a housing inserted into a cylinder head, and is opened toward a combustion chamber. A valve for opening and closing the opening is provided in the chamber. By inserting and sucking the retainer fixed to the end of the valve stem of the valve with an electromagnetic coil, the valve plate portion of the valve opens and closes the opening to inject air and fuel directly into the cylinder. In the air fuel injection type two-stroke engine, a guide surface slidably in contact with an outer peripheral surface of the retainer is formed in a cap or a housing that covers the retainer so that the valve is movable in the axial direction. A valve guide structure for an air-fuel-injected two-stroke engine.