KR102709516B1 - Fuel injection valve and internal combustion engine for ship - Google Patents

Abstract

(Task) Improve the durability of fuel injection valves.
(Solution) The fuel injection valve (3) is formed by accommodating a needle valve (34) in a nozzle body (30). Here, the nozzle body (30) has first and second inner wall portions (31b, 32a) that accommodate the needle valve (34), and a conical first seal portion (32b) formed by tapering the tip end of the second inner wall portion (32a), and the needle valve (34) has, in order from the base side to the tip end side, a sliding portion (34a) that is in contact with the first inner wall portion (31b), a non-sliding portion (34c) that faces the second inner wall portion (32a) with a gap therebetween, and a conical second seal portion (34d) formed by tapering the tip end of the non-sliding portion (34c) more gently than the first seal portion (32b) and contacting the first seal portion (32b). A groove (34e) is formed concavely along the circumferential direction on the outer surface of the non-sliding portion (34c). This groove (34e) is arranged closer to the second seal portion (34d) than to the sliding portion (34a) in the axial direction of the needle valve (34).

Description

FUEL INJECTION VALVE AND INTERNAL COMBUSTION ENGINE FOR SHIP

The present disclosure relates to a fuel injection valve and an internal combustion engine for a ship having the fuel injection valve.

For example, Patent Document 1 discloses a fuel injection valve which is formed by accommodating a needle valve in a nozzle body. Specifically, the nozzle body related to Patent Document 1 has a first sealing portion (first sealing surface) having a cone shape at its tip, while the needle valve related to the same document has a second sealing portion (second sealing surface) having the same cone shape at its tip. According to Patent Document 1, the flow of fuel can be controlled by contacting and separating the first sealing portion and the second sealing portion.

Japanese Patent Publication No. 9-32696

However, in the case of a general fuel injection valve, the outer surface of the second seal portion described in the above-mentioned patent document 1 is more gently inclined than the inner surface of the first seal portion. When the inclination angle is different in this way, the first seal portion and the second seal portion usually have line contact (line contact) rather than surface contact. In this case, a specific part of the second seal portion comes into concentrated contact with the first seal portion.

Because of this, if the contact surface pressure of the first seal portion and the second seal portion (in particular, the maximum value of the contact surface pressure) becomes excessively high, wear and tear, etc. may occur at the contact portion (edge), and there is a possibility that the line contact described above may irreversibly change into surface contact. In the case of change into surface contact, since the contact area becomes large, the contact surface pressure always decreases, resulting in problems such as a permanent decrease in the opening pressure and aggravation of fuel injection deficiency. This is a problem in improving the durability of the fuel injection valve and seeking to extend its service life.

The technology disclosed herein has been made with these points in mind, and its purpose is to improve the durability of a fuel injection valve when the inclination angles of the first seal portion on the nozzle body side and the second seal portion on the needle valve side are made different.

A first aspect of the present disclosure relates to a fuel injection valve configured to inject fuel from a tip by accommodating a needle valve in a nozzle body and opening the needle valve against a spring force. In this fuel injection valve, the nozzle body has an inner wall portion defining a receiving space for the needle valve, and a first conical seal portion formed by tapering a tip portion of the inner wall portion, and the needle valve has, in order from the base side toward the tip side, a sliding portion in contact with the inner wall portion, a non-sliding portion extending in the axial direction of the needle valve and facing the inner wall portion with a gap therebetween, and a second conical seal portion formed by tapering a tip portion of the non-sliding portion more gradually than the first seal portion and contacting the first seal portion, and a groove portion is concavely formed on an outer surface of the non-sliding portion along a circumferential direction of the non-sliding portion.

And, according to the first aspect, the home portion is arranged closer to the second seal portion than to the sliding portion in the axial direction of the needle valve.

The inventors of the present invention studied how to prevent the contact surface pressure between the first seal portion and the second seal portion from becoming excessively high by forming a groove portion in the non-sliding portion to reduce the rigidity near the second seal portion.

However, depending on the location where the groove is formed, there is a possibility that the rigidity near the second seal portion may not be reduced satisfactorily. Therefore, as in the first embodiment, rather than simply forming the groove portion, the rigidity near the second seal portion can be reduced satisfactorily by making the groove portion relatively close to the second seal portion.

In addition, when the groove portion is brought close to the second seal portion, the groove portion is arranged at the tip of the non-sliding portion that extends in the axial direction. By arranging the groove portion at the tip of the non-sliding portion, the groove portion and the portion near the second seal portion are allowed to move flexibly in the radial direction, etc.

In this way, by satisfactorily reducing the rigidity in the vicinity of the second seal portion and configuring the vicinity to be flexibly operable, the first seal portion and the second seal portion can be made to contact each other uniformly in the circumferential direction. As a result, it becomes possible to effectively suppress excessive increase in the contact surface pressure between the first seal portion and the second seal portion, and further improve the durability of the fuel injection valve.

In addition, according to the second aspect of the present disclosure, the depth of the groove portion in the radial direction of the needle valve may be greater than the gap between the groove portion and the second seal portion in the axial direction of the needle valve.

As a result of repeated careful examination by the inventors of the present invention, according to the knowledge obtained, by setting the depth of the groove portion to be greater than the gap between the groove portion and the second seal portion, as in the second embodiment, it is advantageous in effectively suppressing the contact surface pressure between the first seal portion and the second seal portion.

In addition, according to the third aspect of the present disclosure, the groove portion may have an arcuate longitudinal cross-section when viewed in a direction orthogonal to the central axis of the needle valve, and the depth of the groove portion in the radial direction of the needle valve may be larger than the radius of the longitudinal cross-section.

As a result of repeated careful examination by the inventors of the present invention, according to the knowledge obtained, by forming the groove portion in a cross-sectional arc shape as in the third embodiment and setting the depth of the groove portion to be greater than the radius of the arc, it is advantageous in effectively suppressing the contact surface pressure between the first seal portion and the second seal portion.

In addition, the fourth aspect of the present disclosure relates to an internal combustion engine for a ship having the fuel injection valve.

As described above, according to the present disclosure, the durability of a fuel injection valve can be improved.

Figure 1 is a schematic diagram illustrating the configuration of an internal combustion engine for ships.
Figure 2 is a longitudinal cross-sectional view illustrating the structure of a fuel injection valve.
Figure 3 is a drawing illustrating the structure of a needle valve.
Figure 4 is a longitudinal cross-sectional view illustrating an enlarged view of the tip of a fuel injection valve.
Figure 5 is a graph showing the performance of an embodiment of a fuel injection valve.
Fig. 6 is a corresponding drawing of Fig. 2 showing a conventional example of a fuel injection valve.
Figure 7A is a longitudinal cross-sectional view showing an example of a home portion.
Figure 7B is a longitudinal cross-sectional view showing an example of a home section.

Hereinafter, embodiments of the present disclosure will be described based on drawings. In addition, the following description is exemplary. Fig. 1 is a schematic diagram illustrating the configuration of a marine internal combustion engine (hereinafter, simply referred to as “engine (1)”).

Engine (1) is a series multi-cylinder diesel engine equipped with a plurality of cylinders (16). This engine (1) is configured as a two-stroke, one-cycle engine of the uniflow scavenging method, and is installed in large ships such as tankers, container ships, and car carriers.

The engine (1) mounted on the ship is used as a main engine for propelling the ship. For this purpose, the output shaft of the engine (1) is connected to the ship's propeller (not shown) via a propeller shaft (not shown). When the engine (1) operates, its output is transmitted to the propeller, thereby propelling the ship.

In particular, the engine (1) related to the present disclosure is configured as a so-called crosshead type internal combustion engine in order to realize the long stroke. That is, in this engine (1), a piston rod (22) supporting a piston (21) from below and a connecting rod (24) connected to a crankshaft (23) are connected by a crosshead (25).

(1) Main components

Below, the main parts of the engine (1) are described.

As shown in Fig. 1, the engine (1) has a base plate (11) positioned downward, a frame (12) formed on the base plate (11), and a cylinder jacket (13) formed on the frame (12). The base plate (11), the frame (12), and the cylinder jacket (13) are fastened by a plurality of tie bolts and nuts extending in the vertical direction. The engine (1) also has a cylinder (16) formed in the cylinder jacket (13), a piston (21) formed in the cylinder (16), and an output shaft (e.g., a crankshaft (23)) that rotates in conjunction with the reciprocating movement of the piston (21).

The plate (11) constitutes a crank case of the engine (1), and houses a crank shaft (23) and a bearing (26) that supports the crank shaft (23) so that it can rotate freely. The lower end of a connecting rod (24) is connected to the crank shaft (23) via a crank (27).

The furniture (12) accommodates a pair of guide plates (28), a connecting rod (24), and a cross head (25). Of these, a pair of guide plates (28) is formed by a pair of plate-shaped members formed along a piston axial direction and arranged with a gap in the width direction of the engine (1) (left-right direction of the ground in FIG. 1). The connecting rod (24) is arranged between the pair of guide plates (28) with its lower end connected to the crank shaft (23). The upper end of the connecting rod (24) is connected to the lower end of the piston rod (22) via the cross head (25).

Specifically, the crosshead (25) is arranged between a pair of guide plates (28) and slides up and down along each of the guide plates (28). That is, the pair of guide plates (28) are configured to guide the sliding of the crosshead (25). The crosshead (25) is connected to the piston rod (22) and the connecting rod (24) via a crosshead pin (29). The crosshead pin (29) is connected to the piston rod (22) so as to move up and down integrally, while it is connected to the connecting rod (24) so as to rotate the connecting rod (24) with the upper end of the connecting rod (24) as a fulcrum.

The cylinder jacket (13) supports the cylinder liner (14) as an inner tube. The cylinder liner (14) is formed in a cylindrical shape and is inserted into the cylinder jacket (13). The inner space of the cylinder jacket (13) communicates with the inner space of the cylinder liner (14). The piston (21) described above is arranged inside the cylinder liner (14). This piston (21) reciprocates up and down along the inner wall of the cylinder liner (14). In addition, a cylinder cover (15) is fixed to the upper portion of the cylinder liner (14). The cylinder cover (15) forms a cylinder (16) together with the cylinder liner (14).

In addition, an exhaust valve (18) operated by a not-illustrated movable valve device is formed in the cylinder cover (15). The exhaust valve (18) defines a combustion chamber (17) together with a cylinder (16) composed of a cylinder liner (14) and a cylinder cover (15) and a front surface of a piston (21). The exhaust valve (18) opens and closes between the combustion chamber (17) and an exhaust pipe (19). The exhaust pipe (19) has an exhaust port leading to the combustion chamber (17), and the exhaust valve (18) is configured to open and close the exhaust port.

In addition, a fuel injection valve (3) for supplying fuel to the combustion chamber (17) is formed in the cylinder cover (15). The fuel injection valve (3) injects diesel fuel into the interior of the combustion chamber (17).

In addition, the engine (1) related to the present embodiment is equipped with a fuel pump (39) that supplies diesel fuel to the fuel injection valve (3). As shown in Fig. 1, the fuel pump (39) is laid out in the vicinity of the cylinder (16) and is fluidly connected to the fuel injection valve (3) via a fuel injection pipe (not shown).

An exhaust manifold (41) is also arranged near the cylinder (16). This exhaust manifold (41) is connected to the combustion chamber (17) via an exhaust pipe (19). The exhaust manifold (41) receives exhaust gas from the combustion chamber (17) via the exhaust pipe (19), temporarily stores the received exhaust gas, and changes the dynamic pressure of the exhaust gas into a static pressure.

The engine (1) additionally has a supercharger (42) that supercharges combustion gas such as air, and a scavenging trunk (43) that temporarily stores combustion gas compressed by the supercharger (42). The supercharger (42) rotates a compressor (not shown) together with a turbine (not shown) by utilizing the pressure of exhaust gas, and compresses the combustion gas by the compressor. The scavenging trunk (43) is formed so as to communicate with the internal space of the cylinder jacket (13). Combustion gas (hereinafter also referred to as “compressed gas”) compressed by the supercharger (42) flows into the internal space of the cylinder jacket (13) from the scavenging trunk (43), and is supplied from the internal space to the internal space of the cylinder liner (14) (the space surrounded by the inner wall portion (14b) of the cylinder liner (14)) through the scavenging port (14a).

When the engine (1) is operating, diesel fuel is supplied from the fuel injection valve (3) to the interior of the combustion chamber (17), and compressed gas is supplied from the scavenging trunk (43) through the cylinder jacket (13), etc. Accordingly, the diesel fuel is combusted by the compressed gas within the combustion chamber (17).

And, by the energy generated by the diesel fuel, the piston (21) reciprocates up and down along the cylinder liner (14). At this time, when the exhaust valve (18) operates and the combustion chamber (17) opens, the exhaust gas generated by the combustion is pushed out into the exhaust pipe (19). In addition, by the piston (21) reciprocating along the cylinder liner (14), compressed gas (air) is sucked from the cylinder jacket (13) into the cylinder liner (14), and by the piston (21) pushing this in, compressed gas is newly introduced into the combustion chamber (17). By repeating this stroke, combustion of the diesel fuel and scavenging of air within the cylinder (16) are repeatedly performed.

In addition, when the piston (21) reciprocates by combustion, the piston rod (22) reciprocates up and down together with the piston (21). Accordingly, the crosshead (25) connected to the piston rod (22) reciprocates up and down. This crosshead (25) is configured to allow rotation of the connecting rod (24), and rotates the connecting rod (24) with the connection portion with the crosshead (25) as a fulcrum. Then, the crank (27) connected to the lower end of the connecting rod (24) performs cranking motion, and the crankshaft (23) rotates according to the cranking motion. In this way, the crankshaft (23) converts the reciprocating motion of the piston (21) into rotational motion, and rotates the propeller of the ship together with the propeller shaft. Accordingly, the ship is propelled.

However, the fuel injection valve (3) related to the present embodiment is configured to inject fuel from the tip of the fuel injection valve (3) by accommodating a needle valve (34) in the nozzle body (30), as described later, and opening the needle valve (34) against a spring force.

As a result of repeated examinations, the inventors of the present invention have meticulously devised the structure of the needle valve (34) and achieved a longer lifespan of the fuel injection valve (3).

Below, among the configurations of the fuel injection valve (3), the configuration related to the needle valve (34) will be described in detail.

(2) Composition of fuel injection valve

Fig. 2 is a cross-sectional view illustrating the structure of a fuel injection valve (3). Fig. 3 is a drawing illustrating the structure of a needle valve (34). Fig. 4 is a cross-sectional view illustrating an enlarged portion of a tip of a fuel injection valve (3). In Fig. 4, a second body portion (32) described later and a portion of the needle valve (34) showing a depth (B) and a radius of curvature (R) are viewed in cross section.

In addition, in the following description, the direction along the central axis (C) of the needle valve (34) illustrated in Fig. 2 is defined as the “axial direction,” and the direction extending radially from this central axis (C) is defined as the “radial direction.” In addition, the clockwise and counterclockwise rotation directions centered on this central axis (C) are defined as the “circumferential direction.”

The axial direction can also be expressed as the "upward and downward direction." Also, the direction from the base (sliding portion (34a)) side of the needle valve (34) toward the tip (second seal portion (34d)) side along the axial direction is referred to as the "downward direction," and the opposite direction is sometimes referred to as the "upward direction."

The diametric direction is orthogonal to the vertical direction mentioned above. Also, in the diametric direction, one side closer to the central axis (C) is sometimes called the “inner side,” and the other side further from the central axis (C) is sometimes called the “outer side.”

Specifically, the fuel injection valve (3) related to the present embodiment comprises a nozzle body (30), a needle valve (34) accommodated in the nozzle body (30), and an elastic support mechanism (not shown) that applies a spring force to a base portion of the needle valve (34).

Among these, the nozzle body (30) has a first body part (31) for accommodating a base-side portion (sliding portion (34a)) of a needle valve (34), a second body part (32) for accommodating a tip-side portion (connecting portion (34b), a non-sliding portion (34c), a groove portion (34e), and a second seal portion (34d)) of the needle valve (34), and a third body part (33) in which a fuel injection port (33a) is formed.

Among these, the first body part (31) is composed of a substantially cylindrical member with upper and lower ends open. Then, the upper end of a needle valve (34) protrudes from the upper opening of the first body part (31), while the second body part (32) is fitted into the lower opening.

Specifically, the first body part (31) has an introduction path (31a) for introducing fuel from the outside, and a first inner wall part (31b) that, together with the second inner wall part (32a) in the second body part (32), defines a receiving space (S) for a needle valve (34).

As shown in Fig. 2, the inner diameter of the first inner wall portion (31b) substantially matches the outer diameter of the sliding portion (34a) of the needle valve (34). Therefore, the first inner wall portion (31b) is in contact with the sliding portion (34a) of the needle valve (34) and guides the sliding of the sliding portion (34a) in the axial direction. In addition, the lower end of the first inner wall portion (31b) communicates with the lower end of the introduction passage (31a) and defines a substantially dome-shaped space together with the upper end of the second body portion (32). This space functions as a so-called oil storage portion.

Meanwhile, the second body part (32) is formed by a substantially cylindrical member that is open at both ends and has a smaller diameter than the first body part (31). In addition, the lower half of a needle valve (34) is inserted into the upper opening of the second body part (32), while the third body part (33) is mounted in the lower opening.

Specifically, the second body portion (32) is formed with a second inner wall portion (32a) that defines a receiving space for the needle valve (34) together with the first inner wall portion (31b) described above, and a first seal portion (32b) having a cone shape that comes into contact with the tip (second seal portion (34d)) of the needle valve (34).

As shown in Fig. 2, the inner diameter of the second inner wall portion (32a) is larger than the outer diameter of the non-sliding portion (34c) of the needle valve (34). Therefore, the second inner wall portion (32a) does not come into contact with the non-sliding portion (34c) of the needle valve (34), but faces it with a gap therebetween. The second inner wall portion (32a), together with the first inner wall portion (31b) described above, constitutes the “inner wall portion of the nozzle body” in the present embodiment.

In addition, the first seal portion (32b) is configured as a cone shape formed by tapering the tip portion of the second inner wall portion (32a). The first inclination angle (θ1) formed by the inner surface of the first seal portion (32b) is steeper than the second inclination angle (θ2) formed by the outer surface of the second seal portion (34d) described later (θ1 < θ2). In addition, this first inclination angle (θ1) refers to an angle that is opened in a fan shape toward the base side, as shown in Fig. 2, among the angles formed by the hypotenuse (斜邊) of the cone corresponding to the first seal portion (32b) and the central axis (C). As shown in Fig. 3, the second inclination angle (θ2) is also defined in the same manner as the first inclination angle (θ1).

In addition, a fueling hole (32c) extending in the vertical direction is formed at the top of the cone corresponding to the first sealing portion (32b). This fueling hole (32c) is connected to an opening on the upper side of the third body portion (33).

The third body part (33) is formed by a cylindrical member having a bottom and an open upper portion and formed to have a smaller diameter than the second body part (32). An oil supply hole (32c) of the second body part (32) is connected to an opening on the upper side of the third body part (33). In addition, an injection port (33a) extending obliquely downward is formed at the lower end of the third body part (33).

Meanwhile, the needle valve (34) related to the present embodiment has, in order from the upper (base) side to the lower (tip) side, a sliding portion (34a), a connecting portion (34b), a non-sliding portion (34c), a groove portion (34e), and a second seal portion (34d).

Among these, the sliding portion (34a) is configured to be in contact with the inner wall portion of the nozzle body (30) (specifically, the first inner wall portion (31b) of the first body portion (31)). Specifically, the sliding portion (34a) related to the present embodiment is formed in a cylindrical shape having an outer diameter that is approximately the same as the inner diameter of the first inner wall portion (31b), and is arranged in sliding contact with the first inner wall portion (31b).

The connecting portion (34b) is configured to connect the lower end of the sliding portion (34a) and the upper end of the non-sliding portion (34c). Specifically, the connecting portion (34b) related to the present embodiment is formed in a truncated cone shape whose diameter gradually tapers downward. The outer peripheral surface of the connecting portion (34b), like the outer peripheral surface of the non-sliding portion (34c), is configured to face the inner wall portion (second inner wall portion (32a)) of the nozzle body (30) with a gap therebetween in the entire axial and circumferential directions. The connecting portion (34b) is configured to maintain a non-contact state with the inner wall portion (second inner wall portion (32a)) of the nozzle body (30) even when the needle valve (34) moves up and down by spring force.

The non-sliding portion (34c) is configured to extend in the up-and-down direction (axial direction of the needle valve (34)) and to face the inner wall portion of the nozzle body (30) (specifically, the second inner wall portion (32a) of the second body portion (32)) with a space therebetween. Specifically, the non-sliding portion (34c) according to the present embodiment is formed in a cylindrical shape extending in the up-and-down direction. The outer peripheral surface of the non-sliding portion (34c) is configured to face the inner wall portion of the nozzle body (30) (the second inner wall portion (32a)) with a space therebetween, over the entirety in the axial direction and the circumferential direction. The non-sliding portion (34c) is designed to maintain a non-contact state with respect to the inner wall portion (second inner wall portion (32a)) of the nozzle body (30) even when the needle valve (34) moves up and down by spring force.

In short, the non-sliding portion (34c) related to the present embodiment is configured to separate all portions from the inner wall portion of the nozzle body (30) without incorporating a specific portion in the axial direction into the inner wall portion.

The second sealing portion (34d) is configured in a conical shape in which the tip of the non-sliding portion (34c) is tapered more gently than that of the first sealing portion (32b), and is configured to come into contact with the inner surface of the first sealing portion (32b).

As described above, the second inclination angle (θ2) formed by the outer surface of the second seal portion (34d) is gentler than the first inclination angle (θ1) formed by the inner surface of the first seal portion (32b) (θ1 < θ2). This second inclination angle (θ2) refers to an angle that is fan-shaped and opens toward the base side, as shown in Fig. 3, among the angles formed by the hypotenuse of the cone corresponding to the second seal portion (34d) and the central axis (C).

As shown in the enclosing portion (I) of Fig. 4, by making the second seal portion (34d) relatively gently inclined, the outer surface of the second seal portion (34d) and the inner surface of the first seal portion (32b) come into line contact rather than surface contact. In short, when viewed three-dimensionally, the contact surface of the second seal portion (34d) and the first seal portion (32b) forms a ring-shaped curve around the central axis (C).

The groove portion (34e) is formed on the outer surface of the non-sliding portion (34c). This groove portion (34e) is formed concavely along the circumferential direction of the non-sliding portion (34c). Then, the groove portion (34e) related to the present embodiment is arranged closer to the second seal portion (34d) than to the sliding portion (34a) in the axial direction (up-down direction) of the needle valve (34). In other words, in the axial direction of the needle valve (34), the gap (A) between the groove portion (34e) and the second seal portion (34d) is at least narrower than the gap between the groove portion (34e) and the sliding portion (34a).

Specifically, an approximately cylindrical interposition portion (34f) is interposed between the groove portion (34e) and the second seal portion (34d) related to the present embodiment. The dimension of the interposition portion (34f) in the axial direction is the same as the interval (A) between the groove portion (34e) and the second seal portion (34d) described above. As is clear from Fig. 3, this interval (A) is shorter than the interval between the groove portion (34e) and the sliding portion (34a) in the present embodiment.

In addition, as shown in Fig. 4, the groove portion (34e) has an arcuate longitudinal cross-section when viewed in a direction orthogonal to the central axis (C) of the needle valve (34) (in other words, when the longitudinal cross-section extending along the central axis (C) and passing through the central axis (C) is viewed from the front). In particular, the groove portion (34e) related to the present embodiment has an approximately semicircular longitudinal cross-section.

Here, the depth (B) of the groove portion (34e) in the radial direction of the needle valve (34) can be defined as the dimension (particularly, the dimension in the radial direction) of the groove portion (34e) when viewed in the longitudinal cross section, as shown in Fig. 4. For example, when the depth (B) and the radius (hereinafter, also referred to as the “radius of curvature”) (R) of the groove portion (34e) when viewed in the longitudinal cross section are identical (B = R), the longitudinal cross section of the groove portion (34e) becomes a semicircle (a fan-shaped shape with a central angle of 180°). On the other hand, when the depth (B) is smaller than the radius of curvature (R) (B < R), the longitudinal cross section of the groove portion (34e) becomes a fan-shaped shape with a central angle of less than 180°.

In particular, in the present embodiment, the depth (B) is almost equal to the radius of curvature (R), and more specifically, slightly larger than the radius of curvature (R) (B > R). In this case, the longitudinal cross section of the groove portion (34e) has a fan shape having a central angle exceeding 180°.

Fig. 7A illustrates a cross-sectional shape of a groove portion (34e) when the depth (B) is sufficiently larger than the radius of curvature (R). In addition, the cross-sectional shape of the groove portion (34e) is not limited to a fan shape. As shown in Fig. 7B, it may have a U-shaped notch shape. The depth (B) of the groove portion (34e) in the radial direction is larger than the gap (A) between the groove portion (34e) and the second seal portion (34d) in the axial direction of the needle valve (34) (B > A).

(3) Example

Fuel injection valves (3) of Examples 1 to 9 and Comparative Example 1 shown below were prepared. The configurations of each are also shown in Table 1. Then, the inventors of the present invention verified the performance realized in Examples 1 to 9 and Comparative Example 1, and calculated the maximum value of the contact surface pressure (maximum seat surface pressure) between the first seal portion (32b) and the second seal portion (34d) in each fuel injection valve (3).

In addition, in Examples 1 to 9 and Comparative Example 1 below, dimensions other than the spacing (A) between the groove portion (34e) and the second seal portion (34d) and the depth (B) of the groove portion (34e) in the radial direction are common, including the radius of curvature (R) of the groove portion (34e). For example, the size of the diameter (R') of the non-sliding portion (34c) is fixed to a common value in all of Examples 1 to 9 and Comparative Example 1 shown below.

And, the ratio (= R/R') of the radius of curvature (R) to the diameter (R') of the non-sliding portion (34c) is set to 0.105 in all of Examples 1 to 9 and Comparative Example 1. Similarly, in Examples 1 to 9 and Comparative Example 1, the spacing (A) and the depth (B) are exemplified as values divided by the diameter (R') of the non-sliding portion (34c).

In addition, the following examples 1 to 9 correspond to configuration examples having the groove portion (34e) described above, and Comparative Example 1 corresponds to a configuration example not having the groove portion (34e). Specifically, the fuel injection valve (103) shown in Fig. 6 corresponds to the fuel injection valve (3) related to Comparative Example 1.

As shown in Fig. 6, the fuel injection valve (103) related to Comparative Example 1 is formed by accommodating a needle valve (134) in a nozzle body (130), similarly to the above embodiment. The nozzle body (130) has a first body part (131) and a second body part (132) configured similarly to the above embodiment, and defines a accommodating space (S) for the needle valve (134). Meanwhile, the needle valve (134) in Comparative Example 1 has a sliding portion (134a) that is in contact with the inner wall portion of the first body portion (131), a non-sliding portion (134c) that faces the inner wall portion (132a) of the second body portion (132) with a gap therebetween, and a second seal portion (134d) that is formed at the tip of the non-sliding portion (134c) and is more gently inclined than the first seal portion (132b) formed in the second body portion (132).

In addition, among the following Examples 1 to 9, Examples 1 to 3 have a depth (B) (more precisely, equivalent to "B/R'" divided by the diameter (R') of the non-sliding portion (34c); the same applies hereinafter.) of 0.105, Examples 4 to 6 have a depth (B) (B/R') of 0.140, and Examples 7 to 9 have a depth (B) (B/R') of 0.070.

- Example 1 -

In Example 1, the gap A between the groove portion (34e) and the second seal portion (34d) (more precisely, equivalent to “A/R’” divided by the diameter R’ of the non-sliding portion (34c); the same applies hereinafter) is 0.070, the depth B of the groove portion (34e) in the radial direction (B/R’) is 0.105, and the radius of curvature R of the groove portion (34e) (more precisely, equivalent to “R/R’” divided by the diameter R’ of the non-sliding portion (34c); the same applies hereinafter) is 0.105.

- Example 2 -

In Example 2, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.105, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.105, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 3 -

In Example 3, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.140, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.105, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 4 -

In Example 4, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.070, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.140, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 5 -

In Example 5, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.105, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.140, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 6 -

In Example 6, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.140, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.140, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 7 -

In Example 7, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.070, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.070, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 8 -

In Example 8, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.105, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.070, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Example 9 -

In Example 9, the distance (A) (A/R') between the groove portion (34e) and the second seal portion (34d) is 0.140, the depth (B) (B/R') of the groove portion (34e) in the radial direction is 0.070, and the radius of curvature (R) (R/R') of the groove portion (34e) is 0.105.

- Comparative Example 1 -

In Comparative Example 1, the groove portion (34e) is not provided. Therefore, parameters such as the spacing (A) and the depth (B) are not specifically set. The size of the diameter (R') of the non-sliding portion (34c) is the same as in Examples 1 to 9.

(Evaluation method)

As described above, for each fuel injection valve (3) configured, 0.03 J of kinetic energy was applied to the needle valve (34), and the needle valve (34) and the nozzle body (30) were collided. Then, the ratio of the maximum seat surface pressure in each example to the maximum seat surface pressure in the comparative example as 100% was expressed as a percentage, and the relationship between the sizes was visualized by making a graph.

(Evaluation Results)

The evaluation results are as shown in the graph (G) in Fig. 5. In this graph (G), the horizontal axis is the interval (A) and the vertical axis is the maximum surface pressure of the sheet. In addition, a straight line (L0) parallel to the horizontal axis represents the maximum sheet surface pressure (= 100%) in Comparative Example 1, a broken line L1 represents a broken line graph connecting the maximum sheet surface pressures in Examples 1 to 3 (in short, a graph for the case of B/R' = 0.105), a broken line L2 represents a broken line graph connecting the maximum sheet surface pressures in Examples 7 to 9 (in short, a graph for the case of B/R' = 0.070), and a broken line L3 represents a broken line graph connecting the maximum sheet surface pressures in Examples 4 to 6 (in short, a graph for the case of B/R' = 0.140).

As shown in the graph (G), in all of Examples 1 to 9, the maximum surface pressure of the sheet is reduced favorably. In addition, the amount of reduction in the maximum surface pressure of the sheet is reduced more significantly as the depth (B) becomes larger (deeper).

Also, as shown by the comparison between the left plot (plot showing the evaluation result of Example 1) and the center plot (plot showing the evaluation result of Example 2) in the broken line L1, when the depth (B) is larger than the interval (A), the maximum surface pressure of the sheet decreases more significantly than when it is smaller. The same tendency is also shown by the comparison between the right plot (plot showing the evaluation result of Example 6) and the center and left plots (plots showing the evaluation results of Examples 4 and 5) in the broken line L3. On the other hand, in the broken line L2, the relationship between the size of the interval (A) and the depth (B) is not reversed, and it can be seen that the maximum surface pressure of the sheet does not change as significantly as in the other broken lines L1 and L3.

Also, in the graph (G), the broken line L2 indicates the case where the depth (B) is smaller than the radius of curvature (R) (B < R), the broken line L1 indicates the case where the depth (B) matches the radius of curvature (R) (B = R), and the broken line L3 indicates the case where the depth (B) is larger than the radius of curvature (R) (B > R). As shown in the comparison between the broken lines L1 to L3, as the depth (B) increases, the maximum surface pressure of the sheet gradually decreases. In particular, as shown in the comparison between the broken line L3 and the broken lines L1 and L2, when the depth (B) is larger than the radius of curvature (R), the maximum surface pressure of the sheet significantly decreases compared to the case where the depth (B) is equal to or less than the radius of curvature (R). This tendency is common to all intervals (A).

(4) About the durability of the fuel injection valve

As described above, according to the above embodiment and its examples, as shown in Fig. 4, not only is the groove portion (34e) simply formed, but by bringing the groove portion (34e) relatively close to the second seal portion (34d), the rigidity in the vicinity of the second seal portion (34d) can be satisfactorily reduced.

In addition, when the groove portion (34e) is brought close to the second seal portion (34d), the groove portion (34e) is arranged at the tip of the non-sliding portion (34c) that extends long in the axial direction. By arranging the groove portion (34e) at the tip of the non-sliding portion (34c), the portion near the groove portion (34e) and the second seal portion (34d) can move flexibly in the radial direction, etc.

In this way, the rigidity in the vicinity of the second seal portion (34d) is reduced favorably, and the portion in that vicinity is configured to be flexibly operable, together, the first seal portion (32b) and the second seal portion (34d) can be brought into uniform contact in the circumferential direction. As a result, it becomes possible to effectively suppress the contact surface pressure between the first seal portion (32b) and the second seal portion (34d) from becoming excessively high, and further, to improve the durability of the fuel injection valve (3).

In addition, as explained using the graph (G) of Fig. 5, by setting the depth (B) of the groove portion (34e) to be greater than the gap (A) between the groove portion (34e) and the second seal portion (34d), it becomes advantageous in effectively suppressing the contact surface pressure between the first seal portion (32b) and the second seal portion (34d).

In addition, as explained using the graph (G) of Fig. 5, by setting the depth (B) of the groove portion (34e) to be larger than the radius of curvature (R) of the groove portion (34e), it becomes advantageous in effectively suppressing the contact surface pressure between the first seal portion (32b) and the second seal portion (34d).

1: Engine (internal combustion engine for ships)
3: Fuel injection valve
30 : Nozzle body
31: 1st body part
31b: First inner wall (inner wall)
32: 2nd body part
32a: Second inner wall (inner wall)
32b: Part 1
34 : Needle valve
34a : Sliding section
34c: Non-sliding section
34d: Part 2
A: The gap between the home section and the second section
B: Depth of the home
R: Radius of curvature of the home section
C: Central axis
S: Accommodation space

Claims (4)

A fuel injection valve configured to receive a needle valve in a nozzle body and inject fuel from a tip by opening the needle valve against a spring force.
The above nozzle body,
An inner wall portion defining a receiving space for the above needle valve,
It has a first sealing portion in the shape of a cone formed by tapering the tip of the inner wall portion into a tapered shape.
The above needle valves are, in order from the base side to the tip side,
A sliding part in contact with the inner wall,
A non-sliding portion extending in the axial direction of the needle valve and facing the inner wall portion at a gap therebetween,
The tip of the above non-sliding portion is formed by reducing the diameter more gently than the first seal portion, and has a second seal portion in the shape of a cone that comes into contact with the first seal portion.
The above non-sliding portion has a cylindrical shape having a common diameter in each portion in the axial direction,
On the outer surface of the non-sliding portion, a groove is concavely formed along the circumferential direction of the non-sliding portion to reduce the rigidity of the non-sliding portion, thereby reducing the cylindrical shape.
The above home portion is arranged closer to the second seal portion than the sliding portion in the axial direction of the needle valve.
A fuel injection valve characterized by: In paragraph 1,
The depth of the groove portion in the radial direction of the needle valve is greater than the gap between the groove portion and the second seal portion in the axial direction of the needle valve.
A fuel injection valve characterized by: In paragraph 1,
The above-mentioned home portion has a circular cross-section when viewed in a direction perpendicular to the central axis of the needle valve,
The depth of the groove in the radial direction of the needle valve is greater than the radius of the groove when viewed in cross section.
A fuel injection valve characterized by: A fuel injection valve having a fuel injection valve as described in any one of claims 1 to 3.
An internal combustion engine for ships, characterized by:

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