JPH0754658A - Check valve for internal combustion engine - Google Patents

Abstract

PURPOSE:To increase an intake air amount by securing a passage area at the time of valve opening large by arranging a coil spring one end of which is connected to a housing and the other end of which is made a free end in the housing and devising the coil spring to block opening under the natural condition. CONSTITUTION:A flange is formed in the circumference of a housing 52, and a central frame 54 is integrally formed in the center through an arm 53. An opening 55 is opened at a part except for the arm 53 and the central frame 54 of the housing 52. On the central frame 54, one end of a coil spring 60 constituting a valve body is fixed. Additionally, the other end is integrated with a moving member 62. When the inside of a crank chamber is compressed and an intake air flow flows backward, the coil spring 60 works to return to its shrunk state under the natural condition an outer peripheral part 60b moves, the moving member 62 is seated in the housing 52, and a check valve 50 blocks the intake air flow. Consequently, it is possible to secure a passage area at the time of valve opening large and to increase an intake air amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check valve, and in particular to 2
The present invention relates to a check valve applied to a passage such as an intake passage, a scavenging passage or an exhaust passage of an internal combustion engine such as a cycle engine or a 4-cycle engine.

[0002]

2. Description of the Related Art In some cases, a check valve is provided in each passage so that an intake flow, a scavenging air flow, or an exhaust flow flowing in each passage such as an intake passage, a scavenging passage, or an exhaust passage does not flow backward. . As a type of this check valve, a so-called reed valve type is currently put into practical use (for example, Japanese Patent Publication No. 4-1170).
Issue).

The structure of this reed valve type check valve is as follows. That is, it is composed of a housing having an opening at a position corresponding to the passage and a lead piece for closing the opening. The lead piece is arranged at the downstream side opening, and one end of the lead piece is screwed into the housing. It is fixed to be a cantilever, and the opening is normally closed by the returning force of the lead piece itself. Then, when the pressure on the downstream side of the lead piece becomes lower than the pressure on the upstream side, the lead piece is lifted and the opening amount is gradually increased.
On the contrary, when the pressure becomes higher than that on the upstream side, it is returned by the returning force of the lead piece, and the opening is closed.

[0004]

By the way, in order to secure a large flow rate such as the intake air amount, it is necessary to increase the bending amount of the lead piece, that is, the stroke amount. Further, in order to improve the high speed response, the plate thickness of the lead piece must be made as thin as possible.

However, the following problems are hidden in simultaneously satisfying such requirements. That is, as the amount of bending increases, the bending angle of the fixed end of the lead piece increases,
The stress acting on that portion becomes excessive. Therefore, there is a limit to the increase in the amount of bending, and as a result, there is a problem in that the opening area cannot be made very large.

Although it is possible to secure a large opening area by increasing the size of the reed valve, it certainly causes another problem of increasing the size around the reed valve.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a check valve capable of ensuring a large passage area without increasing the size of the check valve. Especially.

[0008]

In order to achieve the above object, a check valve according to claim 1 has a housing provided in a passage and an opening communicating with the passage is provided in the housing, and one end of the check valve is provided. A coil sprue connected to the housing and having the other end as a free end is disposed in the housing,
In a natural condition, the coil spring closes the opening to close the check valve.

[0009]

According to the check valve for an internal combustion engine of the first aspect, the internal stress of the coil spring is relatively small even if the extension amount is relatively large because of the characteristics of the coil spring.
The coil spring can be greatly stroked. By making a large stroke, a large gap can be created between adjacent springs, and as a result, a large passage area can be secured.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 5 show a first embodiment of the present invention, and FIG. 1 shows a schematic view of a crankcase compression type two-cycle engine according to the present invention.

In FIG. 1, 10 is a cylinder, 12 is a crankcase, 14 is a cylinder head, 16 is a spark plug attached to the cylinder head 14, and 17 is a cylinder 1.
Reference numeral 18 denotes a piston that slidably moves up and down in 0, reference numeral 18 denotes a crankshaft rotatably supported by the crankcase 12, and reference numeral 19 denotes a connecting rod that connects the piston 17 and the crankshaft 18.

Reference numeral 13 is a crank chamber formed in the crank case 12. Reference numeral 15 is a combustion chamber formed by the cylinder head 14, the cylinder 10 and the top of the piston 17. The combustion chamber 15 communicates with the exhaust passage 24 and the scavenging passage 22, respectively, and the communication is interrupted by the vertical movement of the piston 17. In addition, the crank chamber 13
Communicates with the intake passage 20, and the communication is interrupted by the vertical movement of the piston 17.

The intake passage 20 is formed not only in the cylinder 10 but also in the carburetor 30 and is open to the atmosphere upstream thereof. The scavenging passage 22 is formed in the cylinder 10, and its upstream end is located in the crank chamber 13.
, The downstream end communicates with the combustion chamber 15, and the piston 17 moves up and down to interrupt the communication. The exhaust passage 24 is formed in the cylinder 10, and its downstream is connected to a muffler (not shown) and is open to the atmosphere.

The intake passage 20 in the carburetor 30 is provided with a venturi 32 and a throttle valve 34 in this order from upstream to downstream. As is well known, the throttle valve 34 is controlled to open and close by an operator (not shown) to adjust the intake air amount. The venturi 32 is connected to a float chamber (not shown) of the carburetor 30 and discharges fuel according to the amount of intake air in the intake passage 20.

Next, the structure of the check valve 50 will be described with reference to FIGS. Reference numeral 52 denotes a housing made of aluminum die cast or a resin molded product, a flange is formed around the housing 52, and a center frame 54 is integrally molded at the center via three arms 53. Arm 5 of housing 52
An opening 55 is opened in a portion excluding 3 and the center frame 54. The center frame 54 has a coil spring 6 which constitutes a valve body.
One end of 0 is fixed. That is, the central portion 60 a of the coil spring 60 is fixed by tightening the bolt 56 via the spring stopper 63. The outer peripheral portion 60b, which is the other end of the coil spring 60, has a moving member 62.
It is integrated with. In addition, this coil spring 60
2 has a conical shape as shown in FIGS. 2 and 5, but may have a triangular pyramid shape, a quadrangular pyramid shape, or another polygonal pyramid shape.
Further, it may have an elliptical shape. A small gap is provided on the outer circumference of the moving member 62 between the moving member 62 and the inner wall surface of the intake passage 20.

As shown in FIGS. 2 and 4, the housing 5
A cylindrical stopper 70 is provided between the 2 and the cylinder 10, and is fixed by tightening four bolts 57. That is, the flange portion 70a is the housing 52
Between the end of the cylinder 10 and the flange of the
It is fixed with a fastening force of 7. Further, the stopper 70 is formed with a flange-shaped stop portion 70b such that the opposite side of the flange portion 70a faces the center of the intake passage 20, and this restricts the maximum extension amount of the coil spring 60. That is, the moving member 62 moves to the left side (in FIG. 2) and comes into contact with the stop portion 70b, so that the coil spring 60 does not extend any further.

In the free state, the coil spring 60 is contracted as shown in FIG. 2 so that the coils are in close contact with each other without a gap and no leakage occurs between them. Further, the moving member 62 is seated on the cylindrical left end of the housing 52, and even at this portion, no leakage occurs. However, when the pressure in the intake passage 20 becomes lower on the downstream side than on the upstream side (the vaporizer 30 side) of the check valve 50, the differential pressure acts on the coil spring 60 to open the valve. That is, since the central portion 60a of the coil spring 60 is fixed to the housing 52, this portion does not move, but the outer peripheral portion 60b is a free end, so the coil spring 60 moves to the left (in FIG. 2) due to this pressure difference. To do. During this movement, the distance between the coils of the coil spring 60 gradually increases. This movement is performed until the moving member 62 contacts the stop portion 70b. Therefore, the intake passage 20
Is in a communication state even at the check valve 50 part. When the coil spring 60 is extended, each coil is slightly twisted so that the coil spring 60 is extended. Even if the amount of extension is relatively large, the amount of twist is distributed over the entire coil. The twist angle of is relatively small, and the stress (shear stress in this case) acting on each coil is small.

Next, the operation of each part and the intake air intake process when the engine is operating will be described with reference to FIGS. 1 and 2. When the crankshaft 18 rotates counterclockwise (in FIG. 1), the piston 17 further descends from the position in the cylinder 10 shown in FIG. 1 and sequentially compresses the crank chamber 13. The air-fuel mixture compressed here is scavenged into the combustion chamber 15 through the scavenging passage 22, and the burned gas in the combustion chamber 15 is expelled to the outside through the exhaust passage 24. When the crankshaft 18 further rotates counterclockwise (in FIG. 1), the piston 1
7 passes through the bottom dead center and rises in the cylinder 10. When the piston 17 further rises, the crank chamber 13 communicates with the intake passage 20, the negative pressure of the crank chamber 13 propagates through the intake passage 20, and acts on the check valve 50.

When the negative pressure in the crank chamber 13 acts on the check valve 50, the coil spring 60 moves leftward (in FIG. 2). Since the central portion 60a is fixed to the housing 52, this portion holds its position, but the outer peripheral portion 60b is a free end, so that the negative pressure causes the moving member 62 to move to the left ( 2), the moving member 62 moves until it abuts on the stop portion 70b, and stops at that position. At this time, the gap between the coils of the coil spring 60 is maximized. That is, the check valve 50 is in the maximum opened state.

When the piston 17 descends past the top dead center, the inside of the crank chamber 13 is compressed and the intake flow tries to flow backward. Then, the pressure on the downstream side of the check valve 50 becomes higher than that on the upstream side, the coil spring 60 acts to return to the natural contracted state, and the outer peripheral portion 60b moves to the right (in FIG. 2). The moving member 62 is moved and seated on the housing 52, and the state shown in FIG. 2 is obtained. In this state,
The check valve 50 blocks intake air flow to the right (in FIG. 2). Therefore, it does not flow back any more.

When the check valve 50 starts to open, the atmosphere is introduced into the intake passage 20 and the venturi 3 inside the carburetor 30.
2 is mixed with the fuel metered from the meter 2, and the throttle valve 34
Then, it passes through the check valve 50 and is introduced into the crank chamber 13. As described above, the introduced air-fuel mixture is guided to the combustion chamber 15 through the scavenging passage 22, is ignited by the ignition plug 16 and burns, and is discharged to the outside through the exhaust passage 24.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be explained. Note that the configuration of the second embodiment is similar to that of the first embodiment, and therefore, for the same parts, description thereof will be omitted by adding 100 to the reference numbers of the first embodiment. The difference will be mainly described below.

FIG. 6 is a vertical sectional view of the check valve 150 alone. This check valve 150 is also attached to the engine as in the first embodiment. However, in the check valve 150, the fixed portion of the coil spring 160 to the housing 152 is opposite to that of the first embodiment. That is, the outer peripheral portion 160b of the coil spring 160 is fixed to the housing 152, and the central portion 160a of the coil spring 160 is a free end.

The coil spring 160 has an outer peripheral portion 160b.
Is fixed to the housing 152 by the spring stopper 163, and the center portion 160a thereof is fixed to the moving member 162 by tightening the spring stopper member 164 with the bolt 158. Similar to the first embodiment, the coil spring 160 is contracted in the natural state as shown in FIG. 6, and the coils are in close contact with each other without a gap, and there is no leakage between them. Therefore, the check valve 150 blocks the intake air flow that tries to flow backward in the intake passage 120.

However, when the pressure in the intake passage 120 becomes lower on the downstream side than on the upstream side (carburetor side) of the check valve 150, the differential pressure acts on the coil spring 160 to open the valve. That is, since the coil spring 160 has its outer peripheral portion 60b fixed to the housing 52, this portion does not move, but the central portion 160a is a free end, so this differential pressure causes it to move to the left (in FIG. 6). To do. During this movement, the coils of the coil spring 160 are gradually separated from each other to increase the distance. This movement is performed until the spring stop member 164 comes into contact with the integrated stop portion 170b from the housing 152 via the three arms. Therefore, the intake passage 120 communicates with the check valve 150.

In the second embodiment, the coil spring 160
The free end of was set to the central portion 160a side of the coil spring 160. On the side of the central portion 160a, the coil wire length is 16
Since it is smaller than 0b side, the mass of the moving part is small,
Responsiveness is improved, and thus high-speed responsiveness of the engine is improved.

If a coil spring having a conical shape is employed as in this embodiment, when the valve is opened, the gap formed between the coils is relatively small in the change of direction with respect to the flow of the passage. The flow path resistance at the stop valve is reduced. Further, since the conical coil spring 60 is adopted in the present embodiment, when the valve is opened, the gap is formed all around and spirally. Therefore, the intake flow flows in all directions along the intake passage 20 and also swirls.

In the present embodiment, an example in which the check valve is installed in the intake passage has been shown, but the present invention is not limited to installation in this intake passage, but may be used in various passages of the internal combustion engine such as a scavenging passage or an exhaust passage. Includes what to install. In addition, even when installed in the intake passage, the one in which the intake passage is directly connected to the crank chamber via the check valve is included.

[0029]

As described in detail above, according to the check valve for an internal combustion engine of the present invention, a large passage area can be secured when the valve is opened, and the intake amount can be increased. In addition, it is possible to secure a relatively large stroke compared to a reed valve. In addition, the stress acting on the constituent members can be relatively small.

[Brief description of drawings]

1 to 5 show a first embodiment of the present invention, and FIGS. 6 to 8 show a second embodiment of the present invention.

FIG. 1 is a schematic diagram of a crankcase compression type two-cycle engine to which a check valve according to a first embodiment of the present invention is applied.

FIG. 2 is a vertical sectional view of a main part.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a cross-sectional view of a part of the check valve in a valve open state.

6 is a cross-sectional view of the check valve according to the second embodiment and is a cross-sectional view taken along line VI-VI of FIG.

FIG. 7 is a right side view of FIG.

FIG. 8 is a left side view of FIG.

[Explanation of symbols]

 10 ... Cylinder 20 ... Intake passage 30 ... Vaporizer 50 ... Check valve 52 ... Housing 55 ... Opening 60 ... ..Coil spring 60a .. Central part 60b .. .. Outer peripheral part 62 .. Moving member 70 .. Stopper

Claims (3)

[Claims] 1. A check valve to be installed in a passage of an internal combustion engine, wherein a housing is provided in the passage, an opening communicating with the passage is provided in the housing, and one end of the check valve is connected to the housing. A check valve for an internal combustion engine in which a coil sprue having the other end as a free end is disposed in the housing, and the coil spring closes the opening to close the check valve in a natural state. 2. The check valve for an internal combustion engine according to claim 1, wherein the coil spring is a conical coil spring. 3. The check valve for an internal combustion engine according to claim 2, wherein the other end of the coil spring is located on the center side of the conical shape of the coil spring.