JPH0749783B2 - Gas engine air-fuel mixer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air-fuel mixer for a gas engine operated using a gaseous fuel such as city gas or liquefied petroleum gas.

<< Prior Art >> The air-fuel mixer of a gas engine (hereinafter simply referred to as a mixer) has almost the same structure as a carburetor of a gasoline engine, and a diaphragm type fuel supply amount control tool (zero governor) by negative pressure generated in the venturi section. Gaseous fuel is sucked in through the valve, and the supply of the air-fuel mixture is adjusted by a slot valve whose opening and closing is controlled by a rotation speed control tool (governor).

<Problems to be solved> However, in the conventional mixer, the same concept as that of the gasoline engine is adopted, and the throttle valve in the mixer has a closed performance as shown in Fig. 6 in order to improve the closing performance in the fully closed state. The edge portion on the side surface is formed in a pin angle shape. In the case of a gasoline engine, the above-mentioned structure has no problem, but in the mixer of the gas engine, there is a problem that the control performance of the engine rotation is deteriorated.

As a result of investigating the cause of this, in a gasoline engine, almost no carbon deposition is observed on the inner peripheral surface of the passage in the slott valve, whereas in the case of a gas engine, the inner peripheral surface of the passage in the slott valve is installed. It has been found that the carbon is deposited on the slag and that the deposited carbon affects the valve operation.

That is, in the case of a gasoline engine, the carbon adhering to the inner peripheral surface of the passage is washed with the blowback fuel and carried away by the inflow mixer into the combustion chamber, whereas in the case of a gas engine, the blowback fuel is expected to have a washing effect. Therefore, carbon will be deposited on the inner circumferential surface of the passage. The carbon deposited on the inner peripheral surface of the passage in the slot valve installation portion is often deposited unevenly.Therefore, when the slot valve is fully closed, there is a gap in the portion where the deposition amount is small and the engine speed increases. Pass. Further, the deposited carbon causes the valve body to stick to each other, which makes it difficult for the valve body to operate when the valve is closed from the fully closed position, and the engine speed becomes too low, or in severe cases, the engine stops.

<< Means for Solving the Problems >> The present invention is for solving the above problems, and therefore, in an air-fuel mixer used for a gas engine, a throttle valve disposed downstream of the venturi portion 5 is used. In the peripheral side surface portion of the valve body 11 of No. 7 at least located far from the valve shaft 12, the front and rear corner end edges 16 in the thickness direction are each formed into a convex curved surface having a convex arc shape in section. It is a thing.

<< Operation >> The present invention operates as follows, for example, as shown in FIG.

The air flow of the mixture of combustion air and fuel gas flowing from the venturi portion 5 flows toward the peripheral side surface 15 along the valve body 11 of the throttle valve 7, and the front side and the rear side of the peripheral side surface 15 respectively. It smoothly passes through the valve gap 18 along a convex curved surface having a convex arcuate cross section formed on each of the edge portions 16 and 16. This allows
Carbon is hardly blown onto the passage inner peripheral surface 14 by the air flow of the air-fuel mixture, and the adhesion of carbon to the passage inner peripheral surface 14 is reduced.

Further, when the peripheral portion of the valve body 11 bites into the carbon layer deposited on the passage inner peripheral surface 14 when the valve body 11 is fully closed, carbon is generated by the convex curved surfaces of the end edges 16 and 16 of the valve body 11. It escapes not only to the front but also to the rear, and there is not much resistance to the biting of the peripheral portion of the valve body 11, and the valve body 11 smoothly bites into the carbon layer.

Further, even if the carbon layer is stuck to the valve body 11 in the fully closed state, since the edge portions 16 and 16 are convex curved surfaces having a convex arcuate cross-section, the carbon layer does not get caught, and the carbon layer Smoothly leave.

<< Examples >> FIGS. 1 to 3 show an embodiment of the present invention. FIG. 1 is a sectional view showing the main part taken out, FIG. 2 is a longitudinal sectional view of a gas mixer, and FIG. 3 is FIG. FIG. 3 is a sectional view taken along line III-III of FIG.

This gas mixer (1) forms a venturi part (5) in a passage (4) transparently provided inside a body (3) connected to an intake port (2) of a gas engine, and the venturi part (5) is formed. A throttle valve (7) whose opening / closing is controlled by a rotation speed control tool (6) is arranged on the intake port (2) side. Gas fuel such as city gas is supplied to the venturi section (5) from a gas supply source (8) via a diaphragm type fuel supply amount control tool (9) and combustion air is supplied via an air cleaner (10). There is.

The valve body (11) of the throttle valve (7) is swingably supported by the valve box (13) via the valve shaft (12). This valve body (1
1) is formed into a substantially elliptical shape corresponding to the shape of the inner peripheral surface (14) of the passage, and its peripheral side surface (15) has circular front and rear end edges (16) as shown in FIG. In addition to being formed in an arc shape, the arc portion is formed in a shape that is connected by a straight line.
Further, a portion of the valve body (11) of the throttle valve (7) in the vicinity of the valve shaft pivotally supporting portion (17) is cut so as to be orthogonal to the valve shaft (12). The valve gap (18) between the inner peripheral surface (14) of the passage and the peripheral side surface (15) of the valve body (11) in the vicinity of is formed wider than the valve gap (19) in other parts. .

4 and 5 show another embodiment of the present invention, in which the peripheral side surface (15) of the valve body (11) of the throttle valve (7) is connected to the front and rear edge portions (16). Are formed in an arc shape, and the arc portions are connected by a curved line. As shown in FIG. 5, the peripheral side surface (15) of the valve body (11) of the throttle valve (7) is It is formed by an arc having the same curvature from the front edge to the rear edge.

In each of the above-mentioned embodiments, the front and rear end portions of the peripheral side surface (15) of the peripheral portion of the valve body (11) excluding the valve shaft pivot portion (17) formed by the linear portion ( 16) is formed in an arc shape, but the peripheral side surface ((16) is formed only in the portion far from the valve shaft (12) of the valve body (11), that is, the portion that largely moves with respect to the rotation angle of the valve body (11). The front and rear edge portions (16) of 15) may be formed in an arc shape.

In the gas mixer configured as described above, since the amount of carbon trapped on the valve peripheral surface is small, even if carbon is unevenly deposited, it will not contact the valve peripheral surface (15) when the valve body (11) is fully closed. A gap is less likely to form between the inner peripheral surface (14) of the passage and the valve body (11) easily separates from the carbon layer when the valve body (11) is opened from the fully closed position, and the rotational speed is increased. The opening / closing control by the control tool (6) can be smoothly performed. .

<< Effect >> The present invention has the following effects because it is configured and operates as described above.

a) When the end edge portion of the peripheral side surface of the valve body is formed in a pin-corner shape as in the conventional case, when the air current of the air-fuel mixture flows through the valve gap to the air supply port side, A turbulent flow is formed in the vicinity of the corner of the edge, and carbon is entrained in the turbulent flow and hits and adheres to the inner peripheral surface of the passage. On the other hand, in the present invention, the air flow of the air-fuel mixture is smoothly guided to the valve gap along the convex curved surface having the convex arc-shaped cross section formed on each of the front and rear edge portions of the peripheral side surface of the valve body. Because it passes through, the airflow is almost undisturbed during the passage. That is, carbon is hardly blown to the inner peripheral surface of the passage by the air flow of the air-fuel mixture, and the adhesion of carbon to the inner peripheral surface of the passage can be reduced.

b) Further, in the conventional valve body in which the end edge portion of the peripheral side surface is formed in a pin angle shape, when the valve body is fully closed, the carbon layer deposited on the inner peripheral surface of the passage in the peripheral portion of the valve body Since it bites by scraping in the swinging direction of the body, the carbon is pushed to the front side in the swinging direction and acts as a resistance to swinging of the valve body, which makes it difficult to completely close the valve body completely. As a result, when the carbon is unevenly deposited, a gap is formed in a portion where the carbon deposition amount is small, and there is a possibility that the rotation of the engine may increase during no-load operation. On the other hand, in the present invention, when the peripheral portion of the valve body digs into the carbon layer on the inner surface of the passage, carbon escapes not only in the front of the valve body but also in the rear due to the convex curved surface of the edge portion. The generated carbon does not have much resistance to the biting in the peripheral portion of the valve body, the valve body can sufficiently bite into the carbon layer, and it is possible to reduce the formation of gaps in the portion where the carbon deposition amount is small.

c) As described above, the adhesion of carbon to the inner peripheral surface of the passage is reduced, and even if carbon is deposited on the inner peripheral surface of the passage, the peripheral portion of the valve body can sufficiently dig into the carbon layer. , The peripheral part of the valve element surely bites into the fully closed position, and even if carbon is unevenly deposited, the valve element can be fully closed during the fully closed operation at no load, and the engine rotation at no load occurs. It can prevent rising.

d) Further, in the conventional valve body in which the end edge portion of the peripheral side surface is formed into a pin angle shape, if carbon sticks to the peripheral portion of the valve body when fully closed, the carbon stuck to the above when opening the valve. However, in the present invention, since the edge of the valve body has a convex curved surface with a convex arcuate cross section, carbon does not get caught at the time of opening the valve and the valve opens smoothly. Can be valve actuated. Therefore, it is possible to prevent insufficient engine rotation and engine stall due to defective valve opening operation.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a sectional view of the main part taken out, FIG. 2 is a longitudinal sectional view of a gas mixer, and FIG. 3 is a III-III line in FIG. Sectional views, FIGS. 4 and 5 are equivalent to FIG. 1 of another embodiment, and FIG. 6 is equivalent to FIG. 1 showing a conventional example. 11 …… The valve body of the throttle valve 7, 12 …… the valve shaft of the throttle valve 7, 15 …… the peripheral side surface of the throttle valve 7, 16 …… the edge of the peripheral side surface 15 of the throttle valve 7.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Tsuda, Inventor Hiroyuki Tsuda, 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Iron Works Co., Ltd.Sakai Works (72) Inventor, Kazuhiko Ogura, Ishizukitamachi, Sakai City, Osaka Prefecture In-house (56) References JP-A-60-47828 (JP, A) Actually opened 51-113520 (JP, U) Actually opened 54-90532 (JP, U) Actually opened 56-99027 (JP, U) Actual development Sho 59-119939 (JP, U) Actual development Sho 56-147344 (JP, U)

Claims (1)

[Claims] 1. An air-fuel mixer, which is arranged in an intake system of a gas engine and mixes combustion air and fuel gas sucked into a combustion chamber, is arranged downstream of a venturi section (5). At least on the peripheral side surface (15) of the valve body (11) of the throttle valve (7), which is located far from the valve shaft (21),
An air-fuel mixer for a gas engine, characterized in that the front and rear edges (16, 16) in the thickness direction are each formed into a convex curved surface having a convex arcuate cross section.