JPH07224745A - Pressure reducing valve for manual starting type internal combustion engine of portable working equipment - Google Patents

Abstract

PURPOSE: To avoid the emission of gas in a combustion chamber to the environment at the time of opening by opening a discharge channel of a pressure reducing valve in the combustion chamber in a conduit connected to a negative pressure source operating when an engine is operated to facilitate start operation due to the reduction of pressure in the combustion chamber. CONSTITUTION: An internal combustion engine 1 which is a single cylinder two-cycle engine used in a chain saw, etc., is provided with a pressure reducing valve 2 including a valve member 13 in a discharge channel 11 connected to a combustion chamber 6 thereof. The valve member 13 acts in the direction of the combustion chamber 6, receives an opening force determining an open position 13a of the valve member 13, and is energized to a close position 13b by increasing burning pressure in the combustion chamber, and a negative pressure acting in the direction opposite to the opening force is applied thereto from a negative pressure source operating when the engine is operated through a connection conduit 4 at the close position 13b. In this case, the discharge channel 11 is opened in the conduit 4 connected to the negative pressure source operating when the engine is operated to avoid the emission of gas in the combustion chamber into the atmosphere when the valve member 13 is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing valve for a combustion chamber for starting an internal combustion engine (particularly manual start), and particularly to an internal combustion engine for hand-held work equipment. In particular, the invention relates to an internal combustion engine according to the preamble of claim 1.
The present invention relates to a pressure reducing valve having an automatically operated valve member (valve body). That is, in detail, a pressure reducing valve of a manual starting type internal combustion engine of a hand-held work equipment, the pressure reducing valve having a valve member arranged in an exhaust channel connected to a combustion chamber of a cylinder of the internal combustion engine, The member is subjected to an opening force acting in the direction of the combustion chamber and determining the open position of the valve member, the increasing combustion pressure in the combustion chamber exerts a force to force the valve member into the closed position, in the closed position the connecting conduit. And a negative pressure acting on the valve member in a direction opposite to the opening force, which is supplied from a negative pressure source that operates during engine operation.

[0002]

2. Description of the Related Art A pressure reducing valve of the type described above, which facilitates a starting operation by reducing the pressure of the combustion chamber by means of a membrane valve provided in the combustion chamber,
It is known from German patent publication 1949541. The membrane valve is provided with a valve member having a valve disk forming a head. The valve member is held in the open position by the compression spring during engine rest and startup operations. After ignition of the engine, the valve disc protruding into the combustion chamber is pressed against the valve seat by the strong compression in the combustion chamber, so that the combustion chamber is closed to the outside. In order to keep the valve in the closed position during the suction cycle, the back side of the membrane valve is connected via a hose to the suction channel, thus the vacuum chamber of the membrane valve is under negative pressure.

[0003]

In this pressure reducing valve, during start-up operation with the valve closed, the air / fuel mixture in the combustion chamber is guided to the outside through the valve by the piston movement, Therefore, there is a problem that considerable environmental pollution occurs.

The object of the present invention is to ensure that the closed position of the valve is more reliably assured against vibrations and the release of combustion chamber gases to the environment is avoided in the open position at a low cost.
It is to improve a pressure reducing valve of the type described above.

[0005]

This problem is solved according to the invention in a pressure reducing valve of the type described above, by means of the features of the characterizing part of claim 1. That is, according to the present invention, the basic feature is that the discharge channel of the pressure reducing valve of the combustion chamber is opened to the connecting conduit to the negative pressure source that operates during engine operation.

[0006]

Since the discharge channel opens to the connecting conduit to the negative pressure source, the fuel / air / air mixture discharged from the pressure reducing valve is
It is surely drawn to the negative pressure source (or intake system) of the engine. The environment is not polluted by this closed circuit. By reducing the compression pressure of the combustion chamber via a single connecting line leading to the negative pressure source of the engine, the pressure reducing valve can be constructed in a technically simple and trouble-free manner from a small number of structural components. During the start-up operation, the air / fuel mixture flows into the combustion chamber through the open valve member, thus reducing the pressure in the combustion chamber to minimize the force exerted by the operator to start the engine.

[0007]

Preferred Embodiment Based on the above basic features of the present invention,
It becomes possible to develop into more preferable embodiments as described below.

In an advantageous embodiment of the invention, the connecting conduit is connected in the crank housing interior space which serves as a negative pressure source for the closing force of the valve member acting on the rear surface of the valve member. 2). If the connecting conduit opens, in particular in the overflow channel connecting the crank housing interior space and the combustion chamber, the air-fuel mixture discharged from the combustion chamber during the starting operation is fed directly into the crank housing interior space and It flows into the combustion chamber again in the suction cycle (claim 3).

As an alternative, the connecting conduit can be opened in the suction channel, in particular in the inlet channel of the crank housing (claim 4).

The valve member of the pressure reducing valve is a ball valve (valve ball) arranged at the end of the exhaust channel facing the combustion chamber and opening toward the combustion chamber.
It is preferable to configure as. Since the gravity of the valve ball acts on the valve member in the direction of the open position, the valve member is naturally opened when the engine is stopped (Claim 5).

The valve ball is advantageously retained in the receiving space of the cylinder wall so that it cannot be lost. in this case,
The valve ball forms an annular gap with the lateral wall of the receiving space (claim 6). The size of the gap determines the switching pressure required to move the bulb from the open position to the closed position. In a preferred embodiment, the receiving chamber for gripping the bulb is designed as part of the drainage channel (claim 7).

In the valve chamber of the connecting conduit, downstream of the valve member, it is expedient to provide a pressure responsive valve (or check valve) which closes when the valve is overpressured and separates the discharge channel from the pressure source. Item 10). For example, the negative pressure created in the internal space of the crank housing is guided from the open (check) valve via the connecting conduit and the discharge channel to the rear face of the ball, thus ensuring that the ball is retained on the valve seat. . On the other hand, the overpressure does not act on the valve ball by closing the check valve.

Other features and advantages of the pressure reducing valve will be apparent from the further claims, the following description and the drawings illustrating embodiments of the invention.

[0014]

The internal combustion engine shown in cross section in FIG.
Preferably, handheld work equipment (e.g., chain saw,
It is a single-cylinder two-cycle engine as used in cutting grinders, meat slicing machines, etc.). The internal combustion engine essentially consists of a crank housing 7 which receives a crankshaft 18. The crankshaft 18 is a piston 2 guided by a cylinder 20 via a connecting rod 16.
4 has a crank neck shaft 19 connected thereto. Cylinder 2
An introduction channel (suction port) 12 opened at the top dead center position of the piston 24 is provided in the leg portion of 0. At the top dead center position of the piston, the fuel / air / air mixture prepared for the operation of the two-stroke engine is introduced through the introduction channel 12 into the inner space 17 of the crank housing 7.
Flow into. When the piston descends, the inflowing fuel / air / air mixture is compressed, and as soon as the piston 24 releases the overflow channel 8, it immediately enters from the crank housing internal space 17 through the overflow channel 8 into the combustion chamber 6 of the cylinder 20. Overflow in the direction of arrow 21. The fuel / air / air mixture that has flowed into the combustion chamber 6 is
In the next rising stroke of the piston 24, the combustion chamber 6
It is further compressed in and-in the region of top dead center-is ignited by the spark plug 9 and thus combustion is initiated. As the piston moves up, the inlet channel 12 is opened again, so that, on the basis of the negative pressure which then prevails in the crank housing interior space 17, a new fuel / air / air mixture is introduced into the crank housing 7 interior space 17.
Flow into.

In the case of a manually started internal combustion engine, the crankshaft is rotated manually. In this case, for the ignition of the internal combustion engine, the necessary compression work of the piston 24 is done manually via the crankshaft 18. In order to reduce the required force for starting the internal combustion engine 1, the pressure reducing valve 2
Is provided in the head of the cylinder 20, preferably in the vicinity of the spark plug 9. The pressure reducing valve 2 opens and closes the exhaust channel 11 that eliminates the compression pressure in the combustion chamber 6.

As is apparent from the enlarged view of FIG. 2, the pressure reducing valve 2
Has a valve member 13, which in the illustrated embodiment is a valve ball 3. The valve ball 3 is provided at the end of the exhaust channel 11 facing the combustion chamber 6. In this case, the end 11a of the discharge channel is expanded in the shape of a truncated cone, thus forming the valve seat 22 of the valve ball 3. The valve seat 22 is followed by a receiving chamber 23 for the valve ball 3, in which case the valve ball is received in the cylindrical receiving chamber 23 and forms an annular gap. The receiving chamber 23, on the side facing the combustion chamber 6,
It is closed by the closing plate 26 and thus the valve ball 3 is retained in the receiving chamber 23 from being lost. The closing plate 26 for closing the inner end of the receiving chamber 23 includes:
A circular inlet 10 having a diameter smaller than that of the valve ball 3 is provided. In the illustrated open position 13a of the valve ball 3, the inlet 10 is configured with another cross-sectional shape (eg polygonal, etc.) so that an open communication is created from the combustion chamber 6 to the receiving chamber 23. Is convenient.

The receiving chamber 23, as shown in FIG.
The wall of the cylinder 20 is machined from the outside and the receiving chamber 23
Bag hole 4 with an inflow port 10 connecting the combustion chamber 6 to the bottom surface
It can consist of zero. The diameter of the inflow port 10 is the same as that of the valve ball 3.
Smaller than the diameter of. The inlet 10, the receiving chamber 23 and the exhaust channel 11 form a continuous communication for releasing the pressure in the combustion chamber.

As shown in FIG. 1, the connecting conduit 4 connecting the pressure reducing valve (or the relief valve) to the negative pressure source is inserted into the discharge channel 11. The connecting conduit 4 can be constructed as a pipe fitted in a cylindrical connecting member 29 inserted in the discharge channel 11.

According to another embodiment of FIG. 2, the housing of the pressure reducing valve 2 can have a connecting stud 27 with a discharge channel 11. The connecting stud 27 has a fir-tree-shaped profile, so that after the connecting conduit 4, which can also be configured as an elastic hose, is fitted, the connecting conduit is retained by the connecting stud 27 in order not to fall off.

As shown in FIG. 1, the connecting conduit 4 connects the exhaust channel 11 to the crank housing interior space 17. In this case, the connecting conduit 11 opens into the overflow channel 8. In this case, the crank housing side end 4 b of the connecting conduit 4 opens into another valve chamber 35 that communicates with the overflow channel 8 via the connecting channel 28. The valve chamber 35 is preferably provided with a pressure responsive valve (or check valve) 5 that opens and closes depending on the pressure in the crank housing internal space 17. When a negative pressure is created in the crank housing interior space 17 and in the valve chamber 35, the valve 5 is opened, so that the negative pressure also acts on the exhaust channel 11 via the connecting conduit 4. In the event of overpressure in the crank housing interior space 17, the valve 5
Is closed, so that the exhaust channel 11 is essentially pressure-tightly separated from the crank housing interior space 17.

In the illustrated embodiment, the pressure responsive (check) valve 5 can be formed from a resilient valve nozzle 36, which can be, for example, conical. The valve nozzle 36 is installed entirely on the wall of the valve chamber 35, preferably in the center of the valve chamber. The valve nozzle 36 is in particular configured in the form of a duck beak, so that a slit-shaped valve opening 37 is produced which is closed when external pressure is exerted on the walls 38, 39 of the valve nozzle 36. Valve nozzle 36
Consists of an elastic material (eg synthetic resin, especially rubber, rubber mixture).

At the start of the internal combustion engine, the work equipment is arranged such that the cylinder is essentially upright. That is, the work equipment is placed on a fixed base, for example, at the time of starting. At this time, as the opening force, the valve ball 3 is opened to the open position 13a shown in FIG.
Gravity held on the valve ball 3 acts in the direction of the arrow 30. A spring (not shown) that loads the valve ball 3 into the open position.
It is also possible to support or induce the opening force by the force of. In this case, the working equipment can be started regardless of the posture.

The combustion chamber 6 includes a pressure reducing valve 2 and an exhaust channel 1.
1 and the check valve 5 to the crank housing interior space 17. When the crankshaft is manually rotated, a part of the compression pressure formed in the combustion chamber 6 with the upward stroke of the piston 24 is guided to the crank housing internal space 17 via the pressure reducing valve 2. Therefore, for example, in a rope starter, the force required to rotate the crankshaft is reduced.

When the fuel / air / air mixture in the combustion chamber 6 is ignited and the internal combustion engine starts to rotate, the pressure in the combustion chamber 6 is rapidly increased by the combustion pressure, and thus the flow through the pressure reducing valve 2 is enhanced. It The flow is defined by the annular gap 35 of the receiving chamber 23, while this annular gap is
It is defined by the inner diameter of the valve ball 3 and the cylindrical receiving chamber 23. If the bulb 3 is exactly centered in the receiving chamber 23, the gap 25 is ideally annular. However, also in the case of the eccentric position, a gap 25 for guiding the flow is obtained. Based on this aperture gap 25, the arrow direction 30
It acts on the valve ball 3 by the flow in which the closing force is increased in the direction opposite to. When the pressure in the combustion chamber 6 exceeds a certain pressure level, the closing force causes the valve member 13, that is,
The valve ball 3 is brought into sealing contact with the valve seat 22. The drainage channel 11 is thus closed and there is no longer any pressure relief.

The gas flowing out when the pressure reducing valve 2 is opened is introduced into the crank housing internal space 17 via the connecting conduit 4 and the check valve 5 in the open state. When the valve member 13 assumes the closed position 13b, the connection to the crank housing interior space 17 is closed tightly.

During the downward stroke of the piston, the crank housing pressure in the internal space 17 rises, and the overpressure of the crank housing also appears in the valve chamber 35, and the outer walls 38, 39 of the valve nozzle 36 of the check valve 5 are exposed. To work. The elastic check valve 5 is deformed, thus closing the valve opening 37 and separating the discharge channel 11 from the valve chamber 35 in a pressure-tight manner. That is, the overpressure generated in the crank housing inner space 17 does not act in the discharge channel 11. On the other hand, during the upward stroke of the piston 24, the valve nozzle 36 returns to its original shape due to the negative pressure (which forms the engine negative pressure source) formed in the crank housing inner space 17, and the valve opening is opened. Therefore, the negative pressure in the crank housing acts in the connecting conduit 4 via the connecting channel 28, the valve chamber 35 and the valve opening 37 and thus in the discharge channel 11. This negative pressure acting in the discharge channel 11 also occurs in the spherical partial shell 3'in the valve seat 22. Thus, the negative pressure exerted on the ball 3 is sufficient to hold it in the closed position 13b. This holding force is assisted in each combustion operation by the combustion pressure acting on another partial surface of the spherical surface, so that when the internal combustion engine is running, the pressure reducing valve is reliably closed. Even during vibration, the drop of the valve member 13 from the valve seat 22 can be reliably eliminated.

Due to the above-described structure of the check valve 5, even after the pressure reducing valve 2 is closed, even if an overpressure is generated in the crank housing 7, the negative pressure formed in the discharge channel 11 is maintained. The reason for this is that when the pressure reducing valve 2 is closed, there is no flow into the discharge channel 11, and when an overpressure is created in the crank housing interior space 17, the check valve 5 is closed and therefore the discharge valve is closed. This is because the negative pressure generated in the channel 11 is maintained beyond the overpressure stage in the crank housing inner space 17.

The exhaust channel 11, the housing for receiving the valve member 13, the connecting conduit 4 and the check valve 5 are preferably constructed as a single structural member, preferably made of an elastic material (eg synthetic resin or rubber). . Thus, the number of parts used is reduced and the pressure reducing valve is easier to install.

The connecting conduit 4 forms part of the negative pressure section of the suction channel of an internal combustion engine, the inlet channel section 1
It can also be connected to 2. In this case, as in the case of the embodiment of FIG. 1, it is preferable to provide the check valve 5.

[0030]

According to the basic feature of the present invention (Claim 1), the air-fuel mixture discharged from the combustion chamber through the pressure reducing valve when the engine is started is supplied to the negative pressure source (or the intake system) of the engine. It is surely sucked and does not leak outside. With this extremely simple closed circuit, manual starting torque can be reduced while preventing environmental pollution. In other words, it has a special effect that it can be started easily.

The basic feature of claim 1 is further defined in claim 2.
It also has a great effect in that it provides a basis for development into the specific preferred embodiments shown below. The additional effects and advantages of claim 2 and the following are as described in [Preferred embodiments] and [Examples], and redundant description is omitted. Particularly, as the negative pressure source, an internal space of the crank housing is used. When used (claim 2), the construction of the connecting conduit (4) can be made simpler. Further, by providing a pressure-responsive (check) valve, more reliable operation can be obtained (claim 10).

[Brief description of drawings]

FIG. 1 is a sectional view of an internal combustion engine having a pressure reducing valve according to the present invention.

FIG. 2 is an enlarged view of a valve member provided in a discharge channel.

FIG. 3 is a drawing of a pressure responsive (check) valve.

FIG. 4 is a sectional view of a cylinder wall in which a pressure reducing valve is provided in a bag hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Pressure reducing valve 4 Connection conduit 6 Combustion chamber 11 Exhaust channel 13 Valve member (3 valve ball) 13a Open position 13b Closed position 20 Cylinder 24 Piston

Claims (12)

[Claims] 1. A pressure reducing valve for a manually started internal combustion engine of a hand-held work equipment, wherein the pressure reducing valve (2) is connected to a combustion chamber (6) of a cylinder (20) of the internal combustion engine (1). An opening force having a valve member (13) arranged in (11), the valve member (13) acting in the direction of the combustion chamber (6) and determining the open position (13a) of the valve member (13). In response, the increasing combustion pressure in the combustion chamber exerts a force to send the valve member (13) to the closed position (13b), and the closed position (1
In 3b), in the type in which a negative pressure is applied via a connecting conduit (4) from a negative pressure source that operates during engine operation and acts on the valve member (13) in the direction opposite to the opening force, the discharge channel A pressure reducing valve, characterized in that (11) is open in a connecting conduit (4) to a negative pressure source that operates during engine operation. 2. The pressure reducing valve according to claim 1, wherein the negative pressure source is an internal space (17) of the crank housing (7). 3. Pressure reducing valve according to claim 2, characterized in that the connecting conduit (4) opens into the overflow channel (8) of the crank housing (7). 4. Reducing valve according to claim 2, characterized in that the connecting conduit (4) opens into the suction channel (12) of the crank housing (7). 5. The valve member (13) comprises a discharge channel (1).
Valve ball (3) arranged at the end facing the combustion chamber (6) of 1)
The pressure reducing valve according to one of claims 1 to 4, characterized in that the gravity of the valve ball (3) is arranged to bias the valve ball (3) to the open position (13a). 6. A valve ball (13) is retained in the receiving chamber (23) against loss and the valve ball (3) together with the side wall of the receiving chamber (23) is an annular gap (2).
5) The pressure reducing valve according to claim 5, wherein the pressure reducing valve is formed. 7. Pressure reducing valve according to claim 6, characterized in that the receiving chamber (23) is configured in the discharge channel (11). 8. The receiving chamber (23) is closed to the combustion chamber (6) by a closing plate (26) provided with an inlet (10) having a diameter smaller than the diameter of the valve ball (3). The pressure reducing valve according to claim 6 or 7, wherein 9. The receiving chamber (23) comprises a blind hole (40) machined from the outside into the wall of the cylinder (20), said blind hole having a diameter smaller than the diameter of the valve ball (3). A pressure reducing valve according to claim 6 or 7, characterized in that an inflow port (10) is provided facing the combustion chamber (6). 10. The valve chamber (35) of the connecting conduit (4) is provided with a pressure responsive valve (5) which is closed in the event of overpressure in the valve chamber. ~ 1 of 9
Pressure reducing valve described in one. 11. The pressure reducing valve according to claim 10, wherein the valve chamber (35) is connected to the internal space (17) of the crank housing (7) via a connection channel (28). 12. The pressure reducing valve according to claim 10, wherein the discharge channel (11), the connecting conduit (4) and the check valve (5) form an integral structural member.