Fuel injection engine

Abstract

To provide a fuel injection type engine that has a high degree of freedom in terms of arranging components in a cylinder head cover, and that can maintain high fuel injection accuracy in a fuel injector 2.SOLUTION: A fuel injector 2 is configured such that: a pressure-receiving part 2aa is provided on an intermediate body portion 2a, which is positioned in the middle in the axial direction of the fuel injector; a clamp 5 comprises a main clamp 6 and an auxiliary clamp 7; the main clamp 6 is disposed on the upper part of a rocker arm bracket 3 and is externally fitted on a stud bolt 4; the auxiliary clamp 7 is externally fitted on an intermediate body portion 2a of the fuel injector 2; and the main clamp 6 presses the pressure-receiving part 2aa of the fuel injector 2 via the auxiliary clamp 7 on the lower side of the main clamp with the fastening force of a nut 4a fastened to the stud bolt 4.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fuel injection engine, and more particularly to a fuel injection engine that has a high degree of freedom in component arrangement within a narrow cylinder head cover and can maintain high fuel injection accuracy of a fuel injector.

Background Art

[0002] Prior to the present invention, the inventor of the present invention proposed the fuel injection engines shown in FIGS. 1 and 2. As shown in FIG. 1 or FIG. 2, the fuel injection engines of the prior cases 1 and 2 include a fuel injector (2) inserted into an injector insertion hole (1a) of a cylinder head (1), a rocker arm bracket (3) disposed within a cylinder head cover (not shown), a stud bolt (4) for fixing the rocker arm bracket (3) to the cylinder head (1), and a clamp (5) disposed above the rocker arm bracket (3). The fuel injector (2) is configured to be press-fixed within the injector insertion hole (1a) by the pressing force of the clamp (5). As a conventional technique of this type of engine, there is the one disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] 《Problem 1》 The degree of freedom in component arrangement within a narrow cylinder head cover is reduced. In the prior case 1 shown in FIG. 1, the fuel injector (2) is inserted into the injector insertion hole (1a), and a two-pronged clamp (5) is fitted to the intermediate body portion (2a) having a smaller diameter below the large-diameter portion (2b) at the upper part of the fuel injector (2) by a lateral slide (S) along its radial direction. Then, the clamp (5) is pressed by the tightening force of the headed bolt (20), and the pressure receiving portion (2aa) of the intermediate body portion (2a) is pressed. For this reason, the bolt mounting portion (20a) of this headed bolt (20) bulges from the rocker arm bracket (3) toward the fuel injector (2) side, and this bolt mounting portion (20a) gets in the way, reducing the degree of freedom in arranging components such as the fuel injector (2) and the intake and exhaust valves, valve springs, valve retainers, etc. (not shown) around it within the narrow cylinder head cover (not shown). The invention of Patent Document 1 also has the same problem.

[0005] <<Problem 2>> The fuel injection accuracy of the fuel injector (2) may decrease. In the prior case 2 shown in FIG. 2, the fuel injector (2) is inserted into the injector insertion hole (1a), and the clamp (5) externally fitted to the stud bolt (4) is lowered (D) along the stud bolt (4), and a pressing force is applied to the clamp (5) by the tightening force of the nut (4a) screwed onto the stud bolt (4). However, when the two-pronged clamp (5) is lowered (D), the clamp (5) hits the large-diameter portion (2b) of the fuel injector (2) above the intermediate body portion (2a), and the lowering (D) is restricted. Therefore, a pressure receiving portion (2aa) is formed in the large-diameter portion (2b), and this is pressed by the clamp (5). For this reason, the fuel injector (2) is pressed at a high position, and the precision components inside the fuel injector (2) are deformed due to buckling, and the fuel injection accuracy of the fuel injector (2) may decrease.

[0006] An object of the present invention is to provide a fuel injection type engine that has a high degree of freedom in arranging components within a narrow cylinder head cover and can maintain the high fuel injection accuracy of the fuel injector.

Means for Solving the Problem

[0007] The main configuration of the present invention is as follows. As illustrated in FIG. 3, a fuel injector (2) inserted into an injector insertion hole (1a) of a cylinder head (1), a rocker arm bracket (3) disposed in a cylinder head cover (1b) illustrated in FIG. 4(B), a stud bolt (4) for fixing the rocker arm bracket (3) to the cylinder head (1) as illustrated in FIG. 3, and a clamp (5) disposed above the rocker arm bracket (3). In a fuel injection type engine configured such that the fuel injector (2) is pressed and fixed within the injector insertion hole (1a) by the pressing force of the clamp (5), As illustrated in FIG. 3, the fuel injector (2) includes a pressure receiving portion (2aa) in an intermediate body portion (2a) located in the middle of its axial length direction. As illustrated in FIG. 3, the clamp (5) includes a main clamp (6) and a sub-clamp (7). The sub-clamp (7) is externally fitted to the intermediate body portion (2a) of the fuel injector (2), and the main clamp (6) is disposed on the upper portion of the rocker arm bracket (3) and externally fitted to the stud bolt (4). As illustrated in FIG. 3, the main clamp (6) is configured to press the pressure receiving portion (2aa) of the intermediate body portion (2a) of the fuel injector (2) through the sub-clamp (7) below it by the tightening force of a nut (4a) screwed onto the stud bolt (4). A fuel injection type engine characterized by this.

Effect of the Invention

[0008] The present invention has the following effects. 《Effect 1》 The degree of freedom in component arrangement within the narrow cylinder head cover (1b) is increased. As illustrated in FIG. 3, in this invention, since the stud bolt (4) for fixing the rocker arm bracket (3) is also used as the mounting bolt of the main clamp (6), unlike the inventions of the prior art example 1 and Patent Document 1, it is not necessary to bulge the bolt mounting portion (20a) of the headed bolt (20) illustrated in FIG. 1 from the rocker arm bracket (3) toward the fuel injector (2) side. Thus, the degree of freedom in arranging components such as the fuel injector (2) and the intake / exhaust valves, valve springs, valve retainers, etc. around it within the narrow cylinder head cover (1b) illustrated in FIG. 4(B) is increased.

[0009] <<Effect 2>> The fuel injection accuracy of the fuel injector (2) can be maintained at a high level. As illustrated in FIG. 3, in this invention, the sub-clamp (7) is externally fitted to the intermediate body portion (2a) of the fuel injector (2), and due to the tightening force of the nut (4a) screwed onto the stud bolt (4), the main clamp (6) presses the pressure receiving portion (2aa) of the intermediate body portion (2a) of the fuel injector (2) via the sub-clamp (7) on its lower side. Thus, unlike the prior art example 2 illustrated in FIG. 2, the fuel injector (2) is pressed at a low position, making it difficult for deformation of the precision parts within the fuel injector (2) due to buckling to occur, and the fuel injection accuracy of the fuel injector (2) can be maintained at a high level.

[0010] <<Effect 3>> The clamp (5) can be inexpensively repaired. As illustrated in FIG. 3, in this invention, since the clamp (5) is composed of the main clamp (6) and the sub-clamp (7), when the sub-clamp (7) wears out early, only the sub-clamp (7) can be replaced, and the clamp (5) can be inexpensively repaired.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Figs. 1 and 2 are diagrams of a prior case, and Figs. 3 to 5 are diagrams for explaining a fuel injection type engine according to an embodiment of the present invention. In this embodiment, a common rail type, multi-valve, vertical in-line multi-cylinder diesel engine will be described.

[0013] In this engine, a plurality of cylinders are arranged side by side in the installation direction of a crankshaft (not shown). In the prior case and embodiment of this invention, the installation direction of the crankshaft is defined as the front-rear direction. One side of the front-rear direction, for example, the side where the engine cooling fan and radiator are arranged, is defined as the front, and the other side, for example, the side where the flywheel is arranged, is defined as the rear. The width direction of the engine is defined as the left-right direction, the left side of an observer facing forward at the position of the engine is defined as the left, the right side is defined as the right, and the height direction of the engine is defined as the up-down direction for illustration and explanation.

[0014] This engine includes an intake device, a fuel supply device, and an exhaust device. Although not shown, the intake and exhaust device includes an intake and exhaust port, an intake and exhaust valve, and a valve operating device. The intake and exhaust port (not shown) is formed in the cylinder head (1) shown in Fig. 4(B). The intake and exhaust valve is a four-valve type with two intake valves and two exhaust valves provided for each cylinder, and is arranged around the fuel injector (2). The valve operating device (not shown) is an overhead valve type including a valve operating camshaft, a push rod, and a rocker arm. The rocker arm (not shown) is pivotally supported by a rocker arm pivot (3a) supported by a rocker arm bracket (3) shown in Fig. 4(A).

[0015] The fuel supply device includes an engine ECU (engine electronic control unit) not shown, a fuel supply pump, a common rail, and a fuel supply pipe. The fuel supply device includes fuel injectors (2) shown in Fig. 3 provided in each cylinder. The liquid fuel (diesel fuel) accumulated in the common rail is pumped from the fuel supply pipe to the fuel injectors (2). By electronic control, the fuel injection valves of the fuel injectors (2) are opened at a predetermined timing for a predetermined time, and a predetermined amount of fuel is injected into each cylinder from the fuel injectors (2) at a predetermined timing.

[0016] As shown in Fig. 4(B), the rocker arm bracket (3) is placed and fixed on the upper surface of the cylinder head (1) and is housed in a cylinder head cover (1b) placed and fixed on the upper surface of the cylinder head (1). As shown in Fig. 4(B), in this engine, stud bolts (4) are screwed and fixed to the cylinder head (1). The stud bolts (4) stand up from the upper surface of the cylinder head (1). The rocker arm bracket (3) is externally fitted to the stud bolts (4), and the rocker arm bracket (3) is pressed and fixed to the upper surface of the cylinder head (1) by the tightening force of a bracket fixing nut (4c) threadedly engaged in the middle part of the stud bolts (4).

[0017] As shown in FIG. 4(B), the fuel injector (2) is inserted into the injector insertion hole (1a) of the cylinder head (1) at a portion near its tip, and a copper annular packing (1c) is disposed between a downward injector pressing surface (2e) provided at a portion near the tip of the fuel injector (2) and the inner end surface (1aa) of the injector insertion hole (1a). By the pressing force applied to the fuel injector (2), the injector pressing surface (2e) is pressed and fixed to the inner end surface (1aa) of the injector insertion hole (1a) via the annular packing (1c), and the space between the injector pressing surface (2e) and the inner end surface (1aa) of the injector insertion hole (1a) is sealed by the annular packing (1c) sandwiched therebetween. As shown in FIG. 4(B), the space between the inner peripheral surface of the injector insertion hole (1a) and the outer peripheral surface of the fuel injector (2) is sealed by a pair of upper and lower O-rings (1d)(1d).

[0018] As shown in FIG. 3, in this engine, a fuel injector (2) inserted into the injector insertion hole (1a) of the cylinder head (1), a rocker arm bracket (3) disposed in the cylinder head cover (1b) shown in FIG. 4(B), a stud bolt (4) for fixing the rocker arm bracket (3) to the cylinder head (1) as shown in FIG. 3, and a clamp (5) disposed above the rocker arm bracket (3) are provided, and the fuel injector (2) is configured to be pressed and fixed within the injector insertion hole (1a) by the pressing force of the clamp (5).

[0019] As shown in FIG. 3, the fuel injector (2) includes a pressure receiving portion (2aa) at an intermediate portion in its axial length direction. As shown in FIG. 3, the clamp (5) includes a main clamp (6) and a sub-clamp (7). The sub-clamp (7) is externally fitted to the intermediate body portion (2a) of the fuel injector (2), and the main clamp (6) is disposed above the rocker arm bracket (3) and externally fitted to the stud bolt (4). As shown in FIG. 3, in this engine, the main clamp (6) presses the pressure receiving portion (2aa) of the intermediate body portion (2a) of the fuel injector (2) via the lower sub-clamp (7) by the tightening force of the nut (4a) screwed onto the stud bolt (4).

[0020] As shown in FIG. 3, in this engine, since the stud bolt (4) that fixes the rocker arm bracket (3) is also used as the mounting bolt of the main clamp (6), unlike the inventions of the prior case 1 and Patent Document 1, it is not necessary to bulge the bolt mounting portion (20a) shown in FIG. 1 from the rocker arm bracket (3) toward the fuel injector (2) side, and the degree of freedom in arranging components such as the fuel injector (2), intake and exhaust valves around it, valve springs, valve retainers, etc. in the narrow cylinder head cover (1b) shown in FIG. 4(B) is increased.

[0021] As shown in FIG. 3, in this engine, the sub-clamp (7) is externally fitted to the intermediate body portion (2a) of the fuel injector (2), and the main clamp (6) presses the pressure receiving portion (2aa) of the fuel injector (2) via the lower sub-clamp (7) by the tightening force of the nut (4a) screwed onto the stud bolt (4). Therefore, unlike the prior case 2, the fuel injector (2) is pressed at a low position, and deformation of precision parts inside the fuel injector (2) due to buckling is less likely to occur, and the fuel injection accuracy of the fuel injector (2) can be maintained at a high level.

[0022] As shown in FIG. 3, in this engine, since the clamp (5) is composed of the main clamp (6) and the sub-clamp (7), when the sub-clamp (7) wears out early, only the sub-clamp (7) can be replaced, and the clamp (5) can be repaired at low cost.

[0023] As shown in FIG. 3, in this engine, the fuel injector (2) has a large diameter portion (2b) that protrudes radially outward above the sub-clamp (7). As shown in Fig. 5(A), the main clamp (6) includes a pair of pressing portions (6a)(6a) bifurcated into two branches, and the separation dimension (6aD) between the pair of pressing portions (6a)(6a) is formed to be larger than the diameter dimension (2bD) of the large-diameter portion (2b) of the fuel injector (2). As shown in Fig. 3, in this engine, when the main clamp (6) externally fitted to the stud bolt (4) is lowered (D) along the stud bolt (4) during clamping of the fuel injector (2), the pair of pressing portions (6a)(6a) of the main clamp (6) pass by both sides of the large-diameter portion (2b) of the fuel injector (2) and are configured to abut against the pair of pressure-receiving portions (7a)(7a) of the sub-clamp (7).

[0024] As shown in Fig. 3, in this engine, even if the fuel injector (2) has a large-diameter portion (2b), the main clamp (6) externally fitted to the stud bolt (4) can be lowered (D) along the stud bolt (4) without being obstructed by the large-diameter portion (2b), abutted against the pressure-receiving portion (7a) of the sub-clamp (7), and by simply tightening the nut (4a) screwed onto the stud bolt (4), the main clamp (6) can press the pressure-receiving portion (2aa) of the fuel injector (2) via the sub-clamp (7) below it, and the clamping operation of the fuel injector (2) can be easily performed.

[0025] As shown in Fig. 3, in this engine, the pressure-receiving portions (7a) of the sub-clamp (7) project outward from both sides of the U-shaped externally fitted portion (7b) externally fitted to the intermediate body portion (2a) of the fuel injector (2) and are arranged radially outward of the large-diameter portion (2b) of the fuel injector (2).

[0026] In this engine, even if the fuel injector (2) has a large-diameter portion (2b), by simply protruding the pressure-receiving portions (7a) of the sub-clamp (7) outward from both sides, interference between the large-diameter portion (2b) during the clamping operation of the fuel injector (2) and the main clamp (6) can be avoided. Since the pressing portion (6a) of the main clamp (6) can pass through both sides of the large-diameter portion (2b) of the fuel injector (2), it is not necessary to change the structure of the fuel injector (2), such as reducing the diameter of the large-diameter portion (2b) of the fuel injector (2), and the fuel injection accuracy of the fuel injector (2) can be maintained at a high level.

[0027] As shown in FIG. 3 or FIG. 4(A), in this engine, the intermediate body portion (2a) of the fuel injector (2) is provided with a pair of flat surfaces (2c)(2c) that are recessed toward the center portion on both sides thereof. With this pair of flat surfaces (2c)(2c), the sub-clamp (7) externally fitted to the intermediate body portion (2a) is prevented from rotating, and a pair of stepped portions (2d)(2d) formed on the lower edge side due to the recesses of this pair of flat surfaces (2c)(2c) serve as a pair of pressure-receiving portions (2aa)(2aa) of the fuel injector (2).

[0028] As shown in FIG. 3 or FIG. 4(A), in this engine, due to the recesses of the pair of flat surfaces (2c)(2c) in the intermediate body portion (2a), a pair of pressure-receiving portions (2aa)(2aa) of the fuel injector (2) are also formed simultaneously, so it does not take much effort to form the pair of pressure-receiving portions (2aa)(2aa).

[0029] As shown in FIG. 3, in this engine, a fuel inlet (2f) is led out rightward from between the large-diameter portion (2b) and the intermediate body portion (2a) of the fuel injector (2), and the leading end portion of a fuel supply pipe led out from the common rail is connected to this fuel inlet (2f). As shown in FIG. 3, in this engine, a rightward connector (2g) is provided at the uppermost part of the fuel injector (2), and the leading end portion of a cable led out from an engine ECU (not shown) is connected to this connector (2g). A control signal is transmitted from the engine ECU to the fuel injector (2), and power is supplied from a battery (not shown) to the fuel injector (2).

[0030] As shown in FIG. 4(B), in this engine, a positioning projection (7c) protruding downward from the externally fitted portion (7b) of the sub-clamp (7) is sandwiched between the outer peripheral surface of the fuel injector (2) and the opposing end surface of the rocker arm bracket (3), and the sub-clamp (7) is positioned.

[0031] As shown in FIG. 4(B), in this engine, when the fuel injector (2) is clamped, the positioning projection (7c) eliminates the displacement of the sub-clamp (7) in the radial direction along the pair of flat surfaces (2c)(2c) of the intermediate cylinder portion (2a) shown in FIG. 3 or FIG. 4(A), and the pressure contact position between the pressing portion (6a) of the main clamp (6) and the pressure receiving portion (7a) of the sub-clamp (7) is determined at a fixed position, suppressing variations in the magnitude and direction of the pressing force applied to the fuel injector (2).

[0032] As shown in FIG. 4(B), in this engine, the main clamp (6) includes a fulcrum portion (6b), a force point portion (6c), and an action point portion (6d). As shown in FIG. 4(B), the fulcrum portion (6b) is provided on the first end portion side of the main clamp (6) that moves away from the fuel injector (2), the force point portion (6c) is provided in the middle portion of the main clamp (6) into which the stud bolt (4) is internally fitted, and the action point portion (6d) is provided on the second end portion side of the main clamp (6) closer to the fuel injector (2).

[0033] As shown in FIG. 4(B), in this engine, the fuel injector (2) can be strongly pressed and fixed within the injector insertion hole (1a) by the amplified pressing force from the action point portion (6d) due to the lever function of the main clamp (6), and the sealing performance of the fuel injector (2) within the injector insertion hole (1a) is also enhanced.

[0034] As shown in FIG. 4(B), in this engine, the fulcrum portion (6b) includes a first partial spherical surface portion (6ba) and a first spherical surface receiving hole (6bb) that fits with the first partial spherical surface portion (6ba). The first partial spherical surface portion (6ba) is fixed to the rocker arm bracket (3), and the first spherical surface receiving hole (6bb) is recessed upward from the bottom surface of the main clamp (6). As shown in FIG. 4(B), the force point portion (6c) includes a second partial spherical surface portion (6ca) and a second spherical surface receiving hole (6cb) that fits with the second partial spherical surface portion (6ca). The second partial spherical surface portion (6ca) is formed on the lower surface of a washer (4b) externally fitted to the stud bolt (4), and the second spherical surface receiving hole (6cb) is formed on the upper surface of the main clamp (6) externally fitted to the stud bolt (4). The second partial spherical surface portion (6ca) of the washer (4b) is press-fitted into the second spherical surface receiving hole (6cb) of the main clamp (6) by the tightening force of a nut (4a) screwed onto the stud bolt (4). As shown in FIG. 4(B), the pressing surface (6aa) of the pressing portion (6a) at the force point portion (6c) of the main clamp (6) that abuts against the flat pressure receiving surface (7aa) of the pressure receiving portion (7a) of the sub-clamp (7) is formed as a downwardly convex curved surface.

[0035] In this engine, due to the spherical surface receiving structure and the convex curved surface receiving structure, it is difficult for concentrated stress due to the edge to be applied to each pressure contact surface of the main clamp (6) and the sub-clamp (7), and the durability of the clamp (5) is enhanced.

[0036] As shown in FIG. 5(A), the main clamp (6) includes a base portion (6e) and a pair of pressing portions (6a)(6a) that branch from the base portion (6e) to the front and rear on the right side. The base portion (6e) has a first spherical surface receiving hole (6bb) on the lower surface closer to the left side. As shown in FIGS. 5(A)(B), the base portion (6e) has a second spherical surface receiving hole (6cb) on the upper surface closer to the right side. As shown in FIG. 3, the second spherical surface receiving hole (6cb) is formed at the opening peripheral edge of a bolt insertion hole (6ea) through which the stud bolt (4) is inserted.

[0037] As shown in Fig. 6(A), the sub-clamp (7) includes a pair of pressure-receiving portions (7a) led out to the outside from both sides in the front and rear of the U-shaped outer fitting portion (7b). As shown in Figs. 6(B) and 6(C), a pair of pressure-receiving surfaces (7aa)(7aa) formed on the upper side of the pair of pressure-receiving portions (7a) are arranged at positions higher than the pressing surface (7ba) formed on the lower side of the outer fitting portion (7b).

[0038] Both the main clamp (6) and the sub-clamp (7) are made of sintered steel products. The main clamp (6) and the sub-clamp (7) may be sintered products, forged products, or cast products made of iron-based metals other than steel or other metals. The materials of the main clamp (6) and the sub-clamp (7) may be different. For example, a cast product of cast iron may be used for the main clamp (6), and a sintered product of steel may be used for the sub-clamp.

[0039] The pressing procedure of the fuel injector (2) by the clamp (5) shown in Fig. 3 or Fig. 4(B) is as follows. As shown in Fig. 4(B), the rocker arm bracket (3) is pressed and fixed to the upper surface of the cylinder head (1) by the tightening force of the bracket fixing nut (4c) screwed onto the stud bolt (4) fixed to the cylinder head (1). Then, the fuel injector (2) is inserted into the injector insertion hole (1a) of the cylinder head (1). Next, as shown in Fig. 3, while horizontally sliding (S) the sub-clamp (7) obliquely downward as indicated by the arrow from the left side of the fuel injector (2), the sub-clamp (7) is externally fitted to the intermediate body portion (2a). As shown in Fig. 4(B), the positioning projection (7c) of the sub-clamp (7) is inserted between the outer peripheral surface of the fuel injector (2) and the opposing end surface of the rocker arm bracket (3).

[0040] Next, as shown in Fig. 3, the main clamp (6) is externally fitted to the stud bolt (4) and lowered (D) along the stud bolt (4), and the pair of pressing portions (6a)(6a) of the main clamp (6) are passed through on both outer sides of the large-diameter portion (2b) of the fuel injector (2). Next, as shown in Fig. 4(A), bring the pair of pressing portions (6a)(6a) of the main clamp (6) into contact with the pair of pressure-receiving portions (7a)(7a) of the sub-clamp (7), and press the main clamp (6) downward via the washer (4b) with the tightening force of the nut (4a) screwed onto the stud bolt (4). Press the pressure-receiving portion (2aa) of the fuel injector (2) via the sub-clamp (7) on the lower side of the main clamp (6), and press-fix the fuel injector (2) within the injector insertion hole (1a).

Explanation of Signs

[0041] (1)…Cylinder head, (1a)…Injector insertion hole, (1b)…Cylinder head cover, (2)…Fuel injector, (2a)…Intermediate body portion, (2aa)…Pressure-receiving portion, (2b)…Large-diameter portion, (2c)…Flat surface, (2d)…Step portion, (3)…Rocker arm bracket, (4)…Stud bolt, (4a)…Nut, (4b)…Washer, (5)…Clamp, (6)…Main clamp, (6a)…Pressing portion, (6aa)…Pressing surface, (6aD)…Separation dimension, (6b)…Fulcrum portion, (6ba)…First partial spherical surface portion, (6bb)…First spherical surface receiving hole, (6c)…Force point portion, (6ca)…Second partial spherical surface portion, (6cb)…Second spherical surface receiving hole, (6d)…Point of action portion, (7)…Sub-clamp, (7a)…Pressure-receiving portion, (7aa)…Pressure-receiving surface, (7b)…Outer fitting portion, (7c)…Positioning projection.

Claims

1. In a fuel injection engine, comprising a fuel injector (2) inserted into an injector insertion hole (1a) of a cylinder head (1), a rocker arm bracket (3) disposed within a cylinder head cover (1b), a stud bolt (4) for fixing the rocker arm bracket (3) to the cylinder head (1), and a clamp (5) disposed on an upper portion of the rocker arm bracket (3), wherein the fuel injector (2) is configured to be pressed and fixed within the injector insertion hole (1a) by the pressing force of the clamp (5). The fuel injector (2) includes a pressure receiving portion (2aa) in an intermediate body portion (2a) located in an intermediate portion in its axial length direction. The clamp (5) includes a main clamp (6) and a sub-clamp (7). The sub-clamp (7) is externally fitted to the intermediate body portion (2a) of the fuel injector (2), and the main clamp (6) is disposed on an upper portion of the rocker arm bracket (3) and externally fitted to the stud bolt (4). The fuel injection engine is characterized in that the tightening force of a nut (4a) screwed onto the stud bolt (4) causes the main clamp (6) to press the pressure receiving portion (2aa) of the fuel injector (2) via the sub-clamp (7) below it.

2. In the fuel injection engine according to Claim 1, the fuel injector (2) includes a large diameter portion (2b) projecting radially outward above the sub-clamp (7). The main clamp (6) includes a pair of pressing portions (6a)(6a) bifurcated into two branches. The separation dimension (6aD) of the pair of pressing portions (6a)(6a) is formed to be larger than the diameter dimension (2bD) of the large diameter portion (2b) of the fuel injector (2). When the main clamp (6) externally fitted to the stud bolt (4) is lowered (D) along the stud bolt (4) during clamping of the fuel injector (2), the pair of pressing portions (6a)(6a) of the main clamp (6) pass along both sides of the large diameter portion (2b) of the fuel injector (2) and are configured to contact a pair of pressure receiving portions (7a)(7a) of the sub-clamp (7).

3. In the fuel injection engine according to Claim 2, A pair of pressure-receiving portions (7a) (7a) of the sub-clamp (7) project outward from both sides of a U-shaped externally-fitted portion (7b) externally fitted to the intermediate body portion (2a) of the fuel injector (2), and are arranged radially outward of the large-diameter portion (2b) of the fuel injector (2). A fuel injection type engine characterized by this.

4. In the fuel injection type engine described in Claim 3, The intermediate body portion (2a) of the fuel injector (2) is provided with a pair of flat surfaces (2c) (2c) recessed toward the center portion on both sides thereof. With this pair of flat surfaces (2c) (2c), the sub-clamp (7) externally fitted to the intermediate body portion (2a) is prevented from rotating. A pair of stepped portions (2d) (2d) formed at the lower edge portion due to the recesses of this pair of flat surfaces (2c) (2c) are used as a pair of pressure-receiving portions (2aa) (2aa) of the fuel injector (2). A fuel injection type engine characterized by this.

5. In the fuel injection type engine described in Claim 3 or Claim 4, A positioning projection (7c) protruding downward from the externally-fitted portion (7b) of the sub-clamp (7) is sandwiched between the outer peripheral surface of the fuel injector (2) and the end surface of the rocker arm bracket (3), and the sub-clamp (7) is positioned. A fuel injection type engine characterized by this.

6. In the fuel injection type engine described in Claim 1, The main clamp (6) includes a fulcrum portion (6b), a force point portion (6c), and an action point portion (6d). The fulcrum portion (6b) is provided on the first end portion side of the main clamp (6) that moves away from the fuel injector (2). The force point portion (6c) is provided in the middle portion of the main clamp (6) into which the stud bolt (4) is internally fitted. The action point portion (6d) is provided on the second end portion side of the main clamp (6) closer to the fuel injector (2). A fuel injection type engine characterized by this.

7. In the fuel injection type engine described in Claim 6, The fulcrum portion (6b) includes a first partial spherical surface portion (6ba) and a spherical surface receiving hole (6bb) that fits with the first partial spherical surface portion (6ba). The first partial spherical surface portion (6ba) is fixed to the rocker arm bracket (3). The spherical surface receiving hole (6bb) is recessed upward from the bottom surface of the main clamp (6). The force application part (6c) includes a second partial spherical surface part (6ca) and a spherical surface receiving hole (6cb) that fits with this second partial spherical surface part (6ca). The second partial spherical surface part (6ca) is formed on the lower surface of a washer (4b) externally fitted to the stud bolt (4), and the spherical surface receiving hole (6cb) is formed on the upper surface of a main clamp (6) externally fitted to the stud bolt (4). With the tightening force of a nut (4a) screwed onto the stud bolt (4), the second partial spherical surface part (6ca) of the washer (4b) is press-fitted into the spherical surface receiving hole (6cb) of the main clamp (6). The pressing surface (6aa) of a pressing part (6a) in the force application part (6c) of the main clamp (6) that is pressure-contact with the flat pressure receiving surface (7aa) of the pressure receiving part (7a) of the sub-clamp (7) is composed of a downwardly convex curved surface. This is a feature of the fuel injection type engine.

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