JP7464809B2 - Fuel injection system - Google Patents

Description

The present invention relates to a fuel injection system that injects fuel into a combustion chamber of an engine.

Patent Document 1 discloses an internal combustion engine equipped with a common rail. The common rail described in Patent Document 1 is fixed to the bottom of the head cover via two mounting parts integrally formed with the cylindrical body of the common rail, and supplies high-pressure fuel to the injector. The injector described in Patent Document 1 is attached to the cylinder head, and injects high-pressure fuel supplied from the common rail into the cylinder. In the internal combustion engine described in Patent Document 1, the common rail and the injector are connected to each other by a fuel pipe.

In contrast, there are fuel injection systems in which the injectors are connected directly to the common rail without going through fuel piping. In such fuel injection systems, when assembling components such as the injectors and common rail, if the common rail is fixed to the head cover or cylinder head or to a support member called a bracket fixed to the head cover or cylinder head before the position of the injectors relative to the cylinder head has been determined, there is a risk that a bending load, for example, will be applied to the injectors that are directly connected to the common rail. If a bending load, for example, is applied to the injectors, there is a risk that the injectors will become distorted.

If the injector is distorted, its position may deviate from the designed position, which may have a significant effect on the amount of fuel injected. The amount of fuel injected by the injector affects engine performance and exhaust gas performance. Therefore, it is desirable to assemble the injector while maintaining the designed position.

One solution is to use special jigs and special tools to assemble the injectors, common rails, and other components, and then attach the injectors to the cylinder head. However, using special jigs and special tools increases the number of steps in the assembly process for the injectors, common rails, and other components, and requires special jigs and special tools for after-sales maintenance in the market.

Patent No. 6468687

The present invention was made in consideration of the above circumstances, and aims to provide a fuel injection system that can prevent distortion of the injector during assembly of parts.

The above problem is solved by the fuel injection system according to the present invention, which is a fuel injection system for injecting fuel into a combustion chamber of an engine, and includes a bracket fixed to a cylinder head of the engine, a fuel accumulator supported and fixed to the bracket, and accumulating the fuel supplied from a fuel pump, and an injector directly connected to the fuel accumulator and attached to the cylinder head, for injecting the fuel supplied from the fuel accumulator into the combustion chamber, and at least one of the fuel accumulator and the bracket has a guide member for guiding the injector to a mounting position on the cylinder head.

According to the fuel injection system of the present invention, the fuel accumulator, which accumulates fuel supplied from the fuel pump, is supported and fixed to a bracket fixed to the cylinder head of the engine. In addition, the injector, which injects fuel supplied from the fuel accumulator into the combustion chamber of the engine, is directly connected to the fuel accumulator and attached to the cylinder head. At least one of the fuel accumulator and the bracket has a guide member that guides the injector to the mounting position of the cylinder head. Therefore, even if the position of the injector relative to the cylinder head is not determined when the fuel accumulator is assembled and fixed to the bracket, the fuel accumulator is assembled and fixed to the bracket while guiding the injector to the mounting position of the cylinder head by the guide member. As a result, the fuel injection system of the present invention can suppress the application of bending loads and the like to the injector connected to the fuel accumulator when the fuel accumulator is assembled and fixed to the bracket and when the injector is mounted to the cylinder head, and suppress the occurrence of distortion in the injector.

In addition, because the fuel accumulator is assembled and fixed to the bracket while the guide member guides the injector to the mounting position of the cylinder head, no dedicated jig or special tool is required. As a result, the fuel injection system of the present invention can prevent an increase in the number of steps in the process of assembling the fuel accumulator to the bracket and the process of assembling the injector to the cylinder head. In addition, the fuel injection system of the present invention can eliminate the need for dedicated jigs and special tools during after-sales maintenance in the market.

In the fuel injection system according to the present invention, preferably, the guide member has a protrusion provided on either the fuel accumulator or the bracket, and a recess provided on the other of the fuel accumulator or the bracket into which the protrusion fits.

According to the fuel injection system of the present invention, the convex portion fits into the concave portion, so that the guide member can more reliably guide the injector to the mounting position of the cylinder head. In other words, when the fuel accumulator is attached to the bracket and when the injector is attached to the cylinder head, the guide member is used as an insertion guide. Therefore, even if the position of the injector relative to the cylinder head is not determined when the fuel accumulator is attached to the bracket and fixed, the fuel accumulator can reliably guide the injector to the mounting position of the cylinder head by the guide member. As a result, the fuel injection system of the present invention can further prevent bending loads and the like from being applied to the injector connected to the fuel accumulator when the fuel accumulator is attached to the bracket and fixed, and when the injector is attached to the cylinder head, and can further prevent distortion of the injector.

In the fuel injection system according to the present invention, preferably, the injector is attached to the cylinder head by being inserted into an insertion hole formed in the cylinder head, and the direction in which the protrusion fits into the recess is parallel to the insertion direction of the injector into the insertion hole.

According to the fuel injection system of the present invention, the direction in which the convex portion fits into the concave portion is parallel to the insertion direction of the injector into the insertion hole. Therefore, the direction in which the fuel accumulator is assembled and fixed to the bracket is parallel to the insertion direction of the injector into the insertion hole. Therefore, the fuel accumulator advances parallel to the insertion direction of the injector into the insertion hole while the guide member guides the injector to the mounting position of the cylinder head, and is assembled and fixed to the bracket. As a result, the fuel injection system of the present invention can further prevent bending loads and the like from being applied to the injector connected to the fuel accumulator when the fuel accumulator is assembled and fixed to the bracket and when the injector is mounted to the cylinder head, and can further prevent distortion of the injector.

In the fuel injection system according to the present invention, the guide member preferably has a plurality of the protrusions and a plurality of the recesses into which the protrusions fit.

According to the fuel injection system of the present invention, the guide member has a plurality of protrusions and a plurality of recesses. Each of the plurality of protrusions fits into each of the plurality of recesses. Therefore, the guide member is used as an insertion guide at a plurality of positions when the fuel accumulator is assembled to the bracket and when the injector is attached to the cylinder head. Therefore, the fuel accumulator is assembled and fixed to the bracket while the guide member guides the injector to the mounting position of the cylinder head at a plurality of positions. As a result, the fuel injection system of the present invention can further prevent bending loads and the like from being applied to the injector connected to the fuel accumulator without using a dedicated jig or special tool, and can further prevent distortion of the injector.

In the fuel injection system according to the present invention, it is preferable that when the injector is attached to the cylinder head, the protrusion begins to fit into the recess before the position of the injector relative to the cylinder head is determined.

According to the fuel injection system of the present invention, when the injector is attached to the cylinder head, the guide member can start guiding the injector to the mounting position on the cylinder head before the position of the injector relative to the cylinder head is determined. This makes it possible for the fuel injection system of the present invention to further prevent bending loads and the like from being applied to the injector connected to the fuel accumulator when the fuel accumulator is assembled and fixed to the bracket and when the injector is attached to the cylinder head, and further prevents distortion of the injector.

In the fuel injection system according to the present invention, preferably, the fuel accumulator is fixed to the bracket using a first fastening member, and the bracket is fixed to the cylinder head using a second fastening member, and is formed in a ladder or lattice shape having a first fixing portion that engages with the first fastening member, a second fixing portion having a hole through which the second fastening member passes, and a reinforcing portion that connects and reinforces the first fixing portion and the second fixing portion that are adjacent to each other.

In the fuel injection system according to the present invention, the fuel accumulator is fixed to the bracket using a first fastening member. The bracket is fixed to the cylinder head using a second fastening member. The bracket is formed in a ladder or lattice shape and has a first fixing portion that engages with the first fastening member, a second fixing portion having a hole through which the second fastening member passes, and a reinforcing portion that connects and reinforces the adjacent first fixing portion and second fixing portion. As a result, the fuel injection system according to the present invention can reduce the number of parts while reinforcing the fixing structure of the fuel accumulator and the injector using the bracket formed in a ladder or lattice shape.

The present invention provides a fuel injection system that can prevent distortion of the injector during assembly of parts.

1 is a perspective view showing an engine equipped with a fuel injection system according to the present invention; 1 is an exploded view showing an engine equipped with a fuel injection system according to an embodiment of the present invention. 1 is an enlarged perspective view of a fuel injection system according to an embodiment of the present invention; 4 is a plan view of the fuel injection system according to the present embodiment as viewed in the direction of the arrow A11 shown in FIG. 3. FIG. 2 is a plan view showing the bracket of the present embodiment. 1 is a perspective view of a fuel injection system according to an embodiment of the present invention, viewed obliquely from above. FIG. 4 is a top view showing the positional relationship between the bracket and the cylinder head in the embodiment. FIG. 2 is a top view showing the cylinder head of the present embodiment. 1 is a perspective view of a fuel accumulator according to an embodiment of the present invention, viewed obliquely from below. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
The embodiments described below are preferred specific examples of the present invention, and therefore various technically preferable limitations are applied to them, but the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is limited to them. In addition, in each drawing, similar components are given the same reference numerals, and detailed descriptions thereof are omitted as appropriate.

FIG. 1 is a perspective view showing an engine equipped with a fuel injection system according to the present invention.
FIG. 2 is an exploded view showing an engine equipped with the fuel injection system according to this embodiment.
1 and 2, for the sake of convenience, components provided below the cylinder head of the engine (such as a cylinder block and a crankcase) are omitted. Also, for the sake of convenience, a fuel pipe 61 is omitted in FIG. 2.

The engine 2 shown in Figures 1 and 2 is, for example, an industrial diesel engine, and is mounted on industrial machinery such as construction machinery, agricultural machinery, and lawn mowers. The engine 2 is an in-line multi-cylinder engine, and in the example shown in Figures 1 and 2, it is an in-line three-cylinder engine. The engine 2 is, for example, an indirect injection (IDI) diesel engine. However, the engine 2 according to this embodiment is not limited to an in-line three-cylinder engine. Furthermore, the engine 2 according to this embodiment is not limited to an in-line diesel engine.

The engine 2 includes a cylinder head 21, a head cover 22, an intake manifold 23, and a fuel injection system 3. The fuel injection system 3 is provided on the upper part of the cylinder head 21. In this specification, the up-down direction corresponds to the up-down direction of an industrial machine such as a construction machine, an agricultural machine, or a lawnmower when the engine 2 is mounted on the industrial machine.

The fuel injection system 3 in this embodiment includes a bracket 5, a fuel pressure storage device 6, an injector 7, and a harness 8.

The bracket 5 is fixed to the upper part of the cylinder head 21 using a plurality of second fastening members 59. In the fuel injection system 3 according to this embodiment, the bracket 5 is fixed to the cylinder head 21 using three second fastening members 59. Specifically, the second fastening members 59 pass from top to bottom through holes 521 (see FIG. 5) formed in the second fixing portion 52 (see FIG. 5) of the bracket 5, and engage with the female threads 213 formed in the upper part of the cylinder head 21. In this way, the bracket 5 is fastened to the cylinder head 21 using the plurality of second fastening members 59. Details of the bracket 5 will be described later.

The fuel accumulator 6 is a so-called common rail type fuel injection device, and accumulates fuel in a common rail, which is pressurized by a fuel pump (not shown) and supplied through a fuel pipe 61. The fuel accumulator 6 is fixed to the bracket 5 using a plurality of first fastening members 62. In the fuel injection system 3 according to this embodiment, the fuel accumulator 6 is fixed to the bracket 5 using three first fastening members 62. Specifically, the first fastening members 62 pass from top to bottom through holes 63 (see FIG. 9) provided in the fuel accumulator 6, and engage with the female threads 511 formed in the first fixing portion 51 of the bracket 5. As a result, the fuel accumulator 6 is fastened to the bracket 5 using a plurality of first fastening members 62. In the bracket 5 shown in FIG. 2, recesses 513 are formed above the female threads 511 in two first fixing portions 51 at both ends of the three first fixing portions 51. Details of the recesses 513 will be described later.

2, the injector 7 is directly connected to the fuel accumulator 6. As described above, the engine 2 shown in FIGS. 1 and 2 is an in-line three-cylinder engine. Therefore, in the fuel injection system 3 according to this embodiment, the three injectors 7 are directly connected to the fuel accumulator 6 and arranged side by side along the arrangement direction A1. The injector 7 is attached to the cylinder head 21. Specifically, as shown in FIG. 2, the lower part of the injector 7 is inserted into an insertion hole 212 formed in the cylinder head 21. In the engine 2 shown in FIG. 2, the sleeve 211 is press-fitted into the insertion hole 212 and fixed to the cylinder head 21. Therefore, in the engine 2 shown in FIG. 2, the hole provided in the sleeve 211 forms a part of the insertion hole 212. The sleeve 211 determines the insertion position of the injector 7 relative to the insertion hole 212. The sleeve 211 does not necessarily have to be provided.

The harness 8 is connected to the injector 7 at a connection part 81 called a coupler or the like, and supplies power to the injector 7. For example, the injector 7 opens a needle valve with power controlled by an electronic control unit (ECU) based on detection signals related to the engine speed and the accelerator opening degree, and is supplied through the harness 8, and injects fuel supplied from the fuel accumulator 6 into the combustion chamber 215 (see Figures 7 and 8) of the engine 2. For example, the combustion chamber 215 shown in Figures 7 and 8 is an auxiliary chamber (i.e., an auxiliary combustion chamber) provided in the cylinder head 21. However, the combustion chamber into which the injector 7 of this embodiment injects fuel is not limited to the auxiliary chamber. In this way, the harness 8 is a harness for driving the injector 7, that is, an injector driving harness.

The harness 8 is held by a holding member 82 and fixed to the bracket 5 via the holding member 82. Specifically, as shown in FIG. 1 and FIG. 2, the holding member 82 holds the harness 8, and is attached to the bracket 5 by inserting the protrusion 821 of the holding member 82 into the hole 531 formed in the third fixing portion 53 of the bracket 5. In this way, the harness 8 is fixed to the bracket 5 via the holding member 82. An example of the holding member 82 is a cable tie that is attached to the outer periphery of the harness 8 to hold the harness 8. However, the harness 8 is not limited to being a cable tie.

FIG. 3 is an enlarged perspective view of the fuel injection system according to this embodiment.
FIG. 4 is a plan view of the fuel injection system according to this embodiment as viewed in the direction of the arrow A11 shown in FIG.
FIG. 5 is a plan view showing the bracket of the present embodiment.

First, the bracket of this embodiment will be described in detail with reference to FIG.
5, the bracket 5 of the present embodiment is formed in a ladder or lattice shape. Specifically, the bracket 5 has a first fixing portion 51, a second fixing portion 52, a third fixing portion 53, a first reinforcing portion 541, a second reinforcing portion 542, and a third reinforcing portion 543.

The first fixing portion 51 has a female thread 511 that meshes with the male thread of the first fastening member 62. As shown in FIG. 5, the bracket 5 of this embodiment has three first fixing portions 51. The three first fixing portions 51 are arranged side by side along the arrangement direction A1 of the three injectors 7. As shown in FIG. 5, in two of the three first fixing portions 51 at both ends, a recess 513 is formed on the upper part of the female thread 511. The recess 513 constitutes a part of the "guide member" of the present invention, and has an inner circumferential surface that is parallel to the insertion direction of the injector 7 and the traveling direction of the first fastening member 62. In other words, the axis of the recess 513 is parallel to the insertion direction of the injector 7 and the traveling direction of the first fastening member 62.

The recess 513 is not limited to being formed in the two first fixing parts 51 at both ends of the three first fixing parts 51, but may be formed corresponding to the protrusion 64 (see FIG. 3). For example, the recess 513 may be formed in the upper part of the female screw 511 in all three first fixing parts 51. In addition, in order to further improve the guiding accuracy and positioning accuracy in the horizontal direction, it is desirable to form the recess 513 in at least two first fixing parts 51 out of the three first fixing parts 51. For example, the recess 513 may be formed in the upper part of the female screw 511 in the central first fixing part 51 and either of the first fixing parts 51 at both ends of the three first fixing parts 51. In addition, the recess 513 may be formed in the upper part of the female screw 511 in the central first fixing part 51 and either of the first fixing parts 51 at both ends of the three first fixing parts 51 as long as it is formed corresponding to the protrusion 64, and may not necessarily be formed in the upper part of the female screw 511, and may not be formed coaxially with the axis of the female screw 511.

The second fixing portion 52 has a hole 521 through which, for example, a male screw of the second fastening member 59 can pass. As shown in FIG. 5, the bracket 5 of this embodiment has three second fixing portions 52. The three second fixing portions 52 are arranged side by side along the arrangement direction A1 of the three injectors 7, and are spaced apart from the three first fixing portions 51 in a direction intersecting the arrangement direction A1 of the three injectors 7.

The third fixing portion 53 has a hole 531 into which the protrusion 821 of the holding member 82 can be inserted. As shown in FIG. 5, the bracket 5 of this embodiment has three third fixing portions 53. The three third fixing portions 53 are arranged side by side along the arrangement direction A1 of the three injectors 7, and are spaced apart from the three first fixing portions 51 in a direction intersecting the arrangement direction A1 of the three injectors 7. The third fixing portion 53 is also provided near the second fixing portion 52.

The first reinforcing portion 541 connects the adjacent first fixing portions 51 and second fixing portions 52 to reinforce the bracket 5. The second reinforcing portion 542 connects the adjacent first fixing portions 51 to reinforce the bracket 5. The third reinforcing portion 543 connects the adjacent second fixing portions 52 to reinforce the bracket 5.
The bracket 5 of this embodiment has the structure described above and is formed in a ladder shape or a lattice shape.

Next, the assembly of the bracket 5 and the fuel accumulator 6 will be described with reference to FIGS.
1 and 2, the injector 7 of this embodiment is directly connected to the fuel accumulator 6. As shown in Figures 3 and 4, when the fuel accumulator 6 is fastened to the bracket 5 using the first fastening member 62, the injector 7 is held in advance in an insertion hole 66 (see Figure 9) of the fuel accumulator 6 by, for example, an O-ring (not shown) attached to the injector 7.

As shown in FIG. 4, a biasing member 72 such as a leaf spring is attached to the injector 7. When the injector 7 is attached to the cylinder head 21 (see FIGS. 1 and 2), the biasing member 72 applies a biasing force to the fuel accumulator 6 and the cylinder head 21. As shown in FIG. 4, before the injector 7 is attached to the cylinder head 21, when the injector 7 is held in the insertion hole 66 of the fuel accumulator 6, the injector 7 is slightly floating above the fuel accumulator 6. That is, the position of the injector 7 relative to the fuel accumulator 6 is not determined. The position of the injector 7 relative to the cylinder head 21 is also not determined. After that, when the fuel accumulator 6 is fastened to the bracket 5 using the first fastening member 62, the injector 7 is sandwiched between the fuel accumulator 6 and the cylinder head 21 while the biasing member 72 applies a biasing force to the fuel accumulator 6 and the cylinder head 21. At this time, the position of the injector 7 relative to the fuel accumulator 6 and the cylinder head 21 is determined.

When the fuel accumulator 6 is fastened to the bracket 5 using the first fastening member 62 while the injector 7 is held in the fuel accumulator 6 and the position of the injector 7 has not been determined, the injector 7 connected directly to the fuel accumulator 6 may be subjected to a bending load, for example. When a bending load, for example, is applied to the injector 7, the injector 7 may be distorted. When the injector 7 is distorted, the position of the injector 7 may deviate from the designed position, which may affect the fuel injection amount. The fuel injection amount of the injector 7 affects the performance and exhaust gas performance of the engine 2. Therefore, it is desirable to assemble the injector 7 while maintaining the designed position.

In contrast, in the fuel injection system 3 according to this embodiment, as shown in FIG. 3 and FIG. 4, the fuel accumulator 6 has a protrusion 64. The protrusion 64, like the recess 513 described above, constitutes a part of the "guide member" of the present invention. That is, the "guide member" of the present invention has a protrusion 64 and a recess 513. The protrusion 64 is formed to correspond to the recess 513 and fits into the recess 513. In other words, the recess 513 is formed to correspond to the protrusion 64 and fits into the protrusion 64.

The protrusion 64 may be provided on the fuel accumulator 6 or on the bracket 5. That is, the protrusion 64 is provided on either the fuel accumulator 6 or the bracket 5. The recess 513 may be provided on the fuel accumulator 6 or on the bracket 5. That is, the recess 513 is provided on the other of the fuel accumulator 6 or the bracket 5. In the example shown in FIG. 3 and FIG. 4, the protrusion 64 is provided on the fuel accumulator 6, and the recess 513 is provided on the bracket 5.

For example, the protrusion 64 is a pipe pin that fits into the recess 513. In the example shown in FIG. 3 and FIG. 4, the pipe pin as the protrusion 64 is formed in a hollow rod shape having an inner diameter through which, for example, the male screw of the first fastening member 62 can pass. The outer peripheral surface of one end of the protrusion 64 is pressed into and fixed to the hole 63 (see FIG. 9) of the fuel accumulator 6, and the outer peripheral surface of the other end of the protrusion 64 fits into the recess 513 formed in the bracket 5. As described above, the bracket 5 may have the protrusion 64. In this case, the outer peripheral surface of one end of the protrusion 64 is pressed into and fixed to the recess 513 of the bracket 5, and the outer peripheral surface of the other end of the protrusion 64 fits into the hole 63 (i.e., the recess) of the fuel accumulator 6. In the following description, a case in which the fuel accumulator 6 has the protrusion 64 and the bracket 5 has the recess 513 will be given as an example.

Note that the protrusion 64 is not limited to being a pipe pin. The protrusion 64 may be a solid rod-shaped member as long as it has a shape that fits into the recess 513. For example, the protrusion 64 may be a sleeve or a collar. The cross-sectional shape of the protrusion 64 is not particularly limited.

As shown in FIG. 3, the fuel injection system 3 according to this embodiment is provided with a plurality of protrusions 64. Specifically, as shown in FIG. 3, two protrusions 64 are fixed to two holes 63 at both ends of the three holes 63 in the fuel accumulator 6. Each of the two protrusions 64 fits into each of the two recesses 513 formed in the bracket 5.

As with the above-mentioned case regarding the recess 513, the protrusion 64 is not limited to being fixed to the two holes 63 at both ends of the three holes 63 of the fuel accumulator 6, but may be provided corresponding to the recess 513. For example, the protrusion 64 may be fixed to all three holes 63 of the fuel accumulator 6. In addition, in order to further improve the guiding accuracy and positioning accuracy in the horizontal direction, it is desirable that the protrusion 64 be fixed to at least two holes 63 of the three holes 63 of the fuel accumulator 6. For example, the protrusion 64 may be fixed to the central hole 63 and one of the holes 63 at both ends of the three holes 63 of the fuel accumulator 6.

4, the protrusion 64 is fixed to the hole 63 of the fuel accumulator 6 in a state where it protrudes from the fastening surface 631 (see FIG. 9) of the fuel accumulator 6. Here, when the injector 7 is inserted into the insertion hole 212 of the cylinder head 21 and attached to the cylinder head 21, the protrusion 64 starts to fit into the recess 513 of the bracket 5 before the position of the injector 7 relative to the cylinder head 21 is determined. In the fuel injection system 3 according to this embodiment, the injector 7 is inserted into the insertion hole 212 of the cylinder head 21, and the positioning surface 71 of the injector 7 comes into contact with the positioning surface 214 of the cylinder head 21, thereby determining the position of the injector 7 relative to the cylinder head 21.

Specifically, as shown in FIG. 4, when the injector 7 is inserted into the insertion hole 212 of the cylinder head 21, the distance D1 between the tip 641 of the protrusion 64 and the fastening surface 512 of the bracket 5 (i.e., the inlet surface of the recess 513 of the bracket 5) is shorter than the distance D2 between the positioning surface 71 of the injector 7 and the positioning surface 214 of the cylinder head 21 (i.e., the inlet surface of the insertion hole 212 of the cylinder head 21). Therefore, when the injector 7 is inserted into the insertion hole 212 of the cylinder head 21, the protrusion 64 begins to fit into the recess 513 of the bracket 5 before the positioning surface 71 of the injector 7 contacts the positioning surface 214 of the cylinder head 21. As a result, the protrusion 64 and the recess 513 can begin to guide the injector 7 to the mounting position of the cylinder head 21 before the position of the injector 7 relative to the cylinder head 21 is determined.

As described above, the recess 513 has an inner peripheral surface that is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21. In other words, the axis of the recess 513 is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21. Therefore, the direction in which the protrusion 64 fits into the recess 513 is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21. Therefore, the direction in which the fuel accumulator 6 is assembled and fixed to the bracket 5 is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21.

As a result, the fuel accumulator 6 guides the injector 7 to the mounting position of the cylinder head 21 by the convex portion 64 and the concave portion 513, while moving parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21, and is assembled and fixed to the bracket 5. In this way, the guide member having the convex portion 64 and the concave portion 513 can more reliably guide the injector 7 to the mounting position of the cylinder head 21 by fitting the convex portion 64 into the concave portion 513. In other words, when the fuel accumulator 6 is assembled to the bracket 5 and when the injector 7 is mounted to the cylinder head 21, the guide member having the convex portion 64 and the concave portion 513 is used as an insertion guide.

As described above, according to the fuel injection system 3 of this embodiment, the fuel accumulator 6, which accumulates fuel supplied from the fuel pump, is supported and fixed to the bracket 5 fixed to the cylinder head 21 of the engine 2. The injector 7, which injects fuel supplied from the fuel accumulator 6 into the combustion chamber 215 of the engine 2 (see Figures 7 and 8), is directly connected to the fuel accumulator 6 and attached to the cylinder head 21. Here, at least one of the fuel accumulator 6 and the bracket 5 (both of the fuel accumulator 6 and the bracket 5 in this embodiment) has guide members (protrusions 64 and recesses 513) that guide the injector 7 to the mounting position of the cylinder head 21. Therefore, when the fuel accumulator 6 is assembled and fixed to the bracket 5, even if the position of the injector 7 relative to the cylinder head 21 has not been determined, the fuel accumulator 6 is assembled and fixed to the bracket 5 while guiding the injector 7 to the mounting position of the cylinder head 21 by the protrusions 64 and recesses 513. As a result, the fuel injection system 3 according to this embodiment can prevent bending loads and the like from being applied to the injector 7 connected to the fuel accumulator 6 when the fuel accumulator 6 is assembled and fixed to the bracket 5, and when the injector 7 is attached to the cylinder head 21, thereby preventing distortion of the injector 7.

In addition, because the fuel accumulator 6 is assembled and fixed to the bracket 5 while guiding the injector 7 to the mounting position of the cylinder head 21 by the convex portion 64 and the concave portion 513, no dedicated jig or special tool is required. As a result, the fuel injection system 3 according to this embodiment can prevent an increase in the number of steps in the process of assembling the fuel accumulator 6 to the bracket 5 and the process of assembling the injector 7 to the cylinder head 21. In addition, the fuel injection system 3 according to this embodiment can eliminate the need for dedicated jigs and special tools during after-sales maintenance in the market.

In addition, the guide member having the convex portion 64 and the concave portion 513 can more reliably guide the injector 7 to the mounting position of the cylinder head 21 by fitting the convex portion 64 into the concave portion 513. In other words, when the fuel accumulator 6 is assembled to the bracket 5 and when the injector 7 is mounted to the cylinder head 21, the guide member having the convex portion 64 and the concave portion 513 is used as an insertion guide. Therefore, even if the position of the injector 7 relative to the cylinder head 21 is not determined when the fuel accumulator 6 is assembled and fixed to the bracket 5, the fuel accumulator 6 can more reliably guide the injector 7 to the mounting position of the cylinder head 21 by the convex portion 64 and the concave portion 513. As a result, the fuel injection system 3 according to this embodiment can further suppress the application of bending loads and the like to the injector 7 connected to the fuel accumulator 6 when the fuel accumulator 6 is assembled and fixed to the bracket 5 and when the injector 7 is mounted to the cylinder head 21, and can further suppress the occurrence of distortion in the injector 7.

The direction in which the convex portion 64 fits into the concave portion 513 is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21. Therefore, the direction in which the fuel accumulator 6 is assembled and fixed to the bracket 5 is parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21. Therefore, the fuel accumulator 6 advances parallel to the insertion direction of the injector 7 into the insertion hole 212 of the cylinder head 21 while guiding the injector 7 to the mounting position of the cylinder head 21 by the convex portion 64 and the concave portion 513, and is assembled and fixed to the bracket 5. As a result, the fuel injection system 3 according to this embodiment can further suppress the application of bending loads and the like to the injector 7 connected to the fuel accumulator 6 when the fuel accumulator 6 is assembled and fixed to the bracket 5 and when the injector 7 is mounted to the cylinder head 21, and can further suppress the occurrence of distortion in the injector 7.

The guide member also has a plurality of protrusions 64 and a plurality of recesses 513. Each of the plurality of protrusions 64 fits into each of the plurality of recesses 513. Therefore, the plurality of protrusions 64 and the plurality of recesses 513 are used as insertion guides at a plurality of positions when the fuel accumulator 6 is assembled to the bracket 5 and when the injector 7 is attached to the cylinder head 21. Therefore, the fuel accumulator 6 is assembled and fixed to the bracket 5 while guiding the injector 7 to the mounting position of the cylinder head 21 at a plurality of positions by the plurality of protrusions 64 and the plurality of recesses 513. As a result, the fuel injection system 3 according to this embodiment can further suppress the application of bending loads and the like to the injector 7 connected to the fuel accumulator 6 without using a dedicated jig or special tool, and can further suppress the occurrence of distortion in the injector 7.

In addition, when the injector 7 is attached to the cylinder head 21, the convex portion 64 and the concave portion 513 can begin to guide the injector 7 to the attachment position of the cylinder head 21 before the position of the injector 7 relative to the cylinder head 21 is determined. As a result, the fuel injection system 3 according to this embodiment can further prevent bending loads and the like from being applied to the injector 7 connected to the fuel accumulator 6 when the fuel accumulator 6 is assembled and fixed to the bracket 5 and when the injector 7 is attached to the cylinder head 21, and can further prevent distortion of the injector 7.

Furthermore, since the injector 7 is directly connected to the fuel accumulator 6, the occurrence of fuel pressure loss can be suppressed, and the number of parts, such as fuel pipes and injector fixing brackets, can be reduced. Here, the bracket 5 supporting the fuel accumulator 6 to which the injector 7 is directly connected has a first fixing portion 51 that engages with the first fastening member 62, a second fixing portion 52 having a hole 521 through which the second fastening member 59 passes, and a first reinforcing portion 541 that connects and reinforces the adjacent first fixing portion 51 and second fixing portion 52, and is formed in a ladder or lattice shape. As a result, the fuel injection system 3 according to this embodiment can reinforce the fixing structure of the fuel accumulator 6 and the injector 7 using the bracket 5 formed in a ladder or lattice shape. The bracket 5 formed in a ladder or lattice shape improves the strength of the fixing structure of the fuel accumulator 6 and the injector 7, so that the vibration generated in the fuel injection system 3 can be reduced. In addition, since the vibration generated in the fuel injection system 3 can be reduced, the noise generated in the fuel injection system 3 can be reduced. As a result, the fuel injection system 3 according to this embodiment can suppress the occurrence of fuel pressure loss, reduce the number of parts, and reduce vibration and noise.

The bracket 5 has a first reinforcing portion 541 that connects and reinforces the adjacent first fixing portion 51 and second fixing portion 52, a second reinforcing portion 542 that connects and reinforces the adjacent first fixing portions 51, and a third reinforcing portion 543 that connects and reinforces the adjacent second fixing portions 52, and is formed in a ladder or lattice shape. This further improves the strength of the fixing structure of the fuel accumulator 6 and the injector 7. This further reduces the vibration generated in the fuel injection system 3. In addition, since the vibration generated in the fuel injection system 3 can be further reduced, the noise generated in the fuel injection system 3 can be further reduced. As a result, the fuel injection system 3 according to this embodiment can suppress the occurrence of fuel pressure loss, reduce the number of parts, and further reduce vibration and noise.

The first fastening member 62 passes from above through a hole 63 formed in the fuel accumulator 6 and engages with the first fixing portion 51 of the bracket 5. The second fastening member 59 passes from above through a hole 521 formed in the second fixing portion 52 of the bracket 5 and engages with the cylinder head 21. Therefore, when performing the work of assembling and fixing the bracket 5 to the cylinder head 21, the worker can easily fasten the bracket 5 to the cylinder head 21 by engaging the second fastening member 59 from above through the hole 521 to the cylinder head 21. Also, when performing the work of assembling and fixing the fuel accumulator 6 to which the injector 7 is directly connected to the bracket 5, the worker can easily fasten the fuel accumulator 6 to which the injector 7 is directly connected to the bracket 5 by engaging the first fastening member 62 from above through the hole 63 of the fuel accumulator 6 to the first fixing portion 51 of the bracket 5. As a result, the fuel injection system 3 according to this embodiment can be easily assembled and improved in workability.

In addition, a sleeve 211 that determines the insertion position of the injector 7 relative to the insertion hole 212 into which the injector 7 is inserted is press-fitted into the insertion hole 212 of the cylinder head 21. Therefore, the sleeve 211 can determine the position of the injector 7 more accurately, and can also prevent the sleeve 211 itself from rotating in the insertion hole 212. As a result, the fuel injection system 3 according to this embodiment can improve the durability and reliability of the injector 7.

FIG. 6 is a perspective view of the fuel injection system according to this embodiment when viewed obliquely from above.
1 and 2, the harness 8 is connected to the injector 7 at a connection portion 81, which is called a coupler or the like, and is fixed to the bracket 5 via a holding member 82. As shown in Fig. 6, the harness 8 is fixed to the third fixing portion 53 of the bracket 5 at a position adjacent to the connection portion 81. Specifically, the harness 8 extends along the arrangement direction A1 of the injectors 7, and is fixed to the third fixing portion 53 of the bracket 5 at a position between adjacent injectors 7.

If the harness for driving the injectors is fixed to, for example, the head cover 22 (see FIG. 1) or the fuel pipe 61, vibrations from the cylinder head 21, the fuel pipe 61, etc. may be transmitted to the harness, amplifying the vibrations of the harness. Amplifying the vibrations of the harness may reduce the durability of the harness or amplify noise. Furthermore, if the harness for driving the injectors is fixed to, for example, a stay for fixing the harness, the number of parts increases.

In contrast, according to the fuel injection system 3 of this embodiment, the harness 8 (i.e., the harness for driving the injector) is connected to the injector 7 and fixed to the bracket 5. As described above with reference to Figs. 1 and 2, the bracket 5 is fixed to the cylinder head 21. The fuel accumulator 6 is fixed to the bracket 5 fixed to the cylinder head 21 and directly connected to the injector 7. Therefore, the part where the harness 8 is connected to the injector 7 and the part where the harness 8 is fixed to the bracket are in the same vibration system via the bracket 5, the fuel accumulator 6, and the injector 7. As a result, the fuel injection system 3 of this embodiment can suppress the vibration of the harness 8 for driving the injector. In addition, since the vibration of the harness 8 is suppressed, the fuel injection system 3 of this embodiment can suppress breakage and deterioration at the connection part 81 of the harness 8, suppress the deterioration of the durability of the harness 8, and suppress the amplification of noise. Furthermore, the harness 8 is fixed to the bracket 5 supporting the fuel accumulator 6, not to a special part for fixing the harness. Therefore, the fuel injection system 3 according to this embodiment can suppress vibrations in the harness 8 for driving the injector while preventing an increase in the number of parts.

The harness 8 is fixed to the bracket 5 at a position adjacent to the connection 81 connected to the injector 7. Therefore, the portion where the harness 8 is fixed to the bracket 5 can support the harness 8 at a position close to the connection 81 between the harness 8 and the injector 7. This allows the fuel injection system 3 according to this embodiment to further suppress vibrations of the harness 8 used to drive the injector.

The harness 8 extends along the arrangement direction A1 of the injectors 7, and is fixed to the bracket 5 at a position between adjacent injectors 7. Therefore, the portion where the harness 8 is fixed to the bracket 5 can support the harness 8 extending along the arrangement direction A1 of the injectors 7 at a position near the connection portion 81 between the harness 8 and the injector 7. This allows the fuel injection system 3 according to this embodiment to further suppress vibration of the harness 8 for driving the injectors.

The holding member 82 that holds the harness 8 is attached to the bracket 5 to fix the harness 8 to the bracket 5. Therefore, the harness 8 is more securely fixed to the bracket 5 and is fixed to the bracket 5 with a simple structure. As a result, the fuel injection system 3 according to this embodiment can securely fix the harness 8 to the bracket 5 by the holding member 82 while minimizing an increase in the number of parts, thereby suppressing vibration of the harness 8.

FIG. 7 is a top view showing the positional relationship between the bracket and the cylinder head in this embodiment.
FIG. 8 is a top view showing the cylinder head of the present embodiment.

1 and 2, the bracket 5 is fixed to the upper part of the cylinder head 21 by using the second fastening member 59. At this time, as shown in FIG. 7, the bracket 5 is placed on the upper part of the cylinder head 21, straddling the upper part of the combustion chamber 215 provided in the cylinder head 21. In the example shown in FIG. 7, the second fixing part 52 and the third reinforcing part 543 of the bracket 5 straddle the upper part of the combustion chamber 215 provided in the cylinder head 21. However, the part of the bracket 5 that straddles the combustion chamber 215 is not limited to the second fixing part 52 and the third reinforcing part 543.

As shown in FIG. 8, the cylinder head 21 has a mounting surface 216. The bracket 5 is placed on the mounting surface 216 of the cylinder head 21 and fixed to the cylinder head 21. As shown in FIG. 8, the mounting surface 216 is provided in an area that spans above the combustion chamber 215 provided in the cylinder head 21. For example, the combustion chamber 215 shown in FIG. 7 and FIG. 8 is an auxiliary chamber (i.e., an auxiliary combustion chamber) formed inside the cylinder head 21.

As described above with reference to Figures 1 to 6, the injector 7 is attached to the top of the cylinder head 21. The fuel accumulator 6 and the fuel pipe 61 are located above and away from the cylinder head 21. Therefore, if the bracket 5 does not exist, a relatively large amount of space exists above and above the cylinder head 21. This may make it easier for combustion noise generated in the combustion chamber 215 to leak above the cylinder head 21.

In contrast, according to the fuel injection system 3 of this embodiment, the bracket 5 supporting the fuel accumulator 6 is placed on the top of the cylinder head 21 across the combustion chamber 215 of the engine 2 and fixed to the top of the cylinder head 21. In this way, since the bracket 5 is placed and fixed on the top of the cylinder head 21 in a state of straddling the top of the combustion chamber 215 of the engine 2, it is possible to prevent the combustion noise generated in the combustion chamber 215 of the engine 2 from leaking above the cylinder head 21. In addition, the bracket 5 supporting the fuel accumulator 6 functions as a heavy object fixed to the top of the cylinder head 21, and the part fixed to the cylinder head 21 exerts a damping effect. Therefore, the bracket 5 has a function of blocking the combustion noise generated in the combustion chamber 215 of the engine 2, i.e., a sound insulation function. As a result, the fuel injection system 3 of this embodiment can reduce the combustion noise generated in the combustion chamber 215 of the engine 2.

In addition, when the combustion chamber 215 is an auxiliary chamber formed inside the cylinder head 21, the bracket 5 can prevent the combustion noise generated in the auxiliary chamber from leaking above the cylinder head 21 directly above the auxiliary chamber. In addition, the bracket 5 supporting the fuel accumulator 6 functions as a heavy object fixed to the top of the cylinder head 21, and exerts a damping effect in the part fixed to the cylinder head 21. Therefore, the bracket 5 has a function of blocking the combustion noise generated in the auxiliary chamber, i.e., a sound insulation function. As a result, when the combustion chamber 215 is an auxiliary chamber formed inside the cylinder head 21, the fuel injection system 3 according to this embodiment can efficiently reduce the combustion noise generated in the auxiliary chamber of the auxiliary chamber type engine.

The cylinder head 21 also has a mounting surface 216 on which the bracket 5 is placed. Therefore, the fuel injection system 3 according to this embodiment can suppress distortion of the bracket 5 when the bracket 5 is assembled and fixed to the cylinder head 21, and can stably fix the bracket 5 to the upper part of the cylinder head 21. The fuel injection system 3 according to this embodiment can also improve the ease of assembly of the bracket 5 to the upper part of the cylinder head 21. Furthermore, when the combustion chamber 215 is a sub-chamber formed inside the cylinder head 21, the mounting surface 216 of the cylinder head 21 is provided in an area that straddles the upper part of the sub-chamber provided in the cylinder head 21 of the sub-chamber type engine. Therefore, the bracket 5 is stably placed on the mounting surface 216 provided in an area that straddles the upper part of the sub-chamber, and is stably fixed to the upper part of the cylinder head 21. As a result, the bracket 5 can suppress vibrations caused by combustion in the sub-chamber from being transmitted to the upper part of the cylinder head 21. As a result, when the combustion chamber 215 is an auxiliary chamber formed inside the cylinder head 21, the fuel injection system 3 according to this embodiment can reduce the combustion noise generated in the auxiliary chamber and the vibrations caused by the combustion in the auxiliary chamber.

FIG. 9 is a perspective view of the fuel accumulator of this embodiment as viewed obliquely from below.
For ease of explanation, the protrusions 64 that are press-fitted and fixed in the holes 63 are omitted in FIG.

3 and 4, the protrusion 64 (not shown in FIG. 9) is press-fitted into the hole 63 of the fuel accumulator 6 and fixed therein. A fastening surface 631 is provided around the hole 63. The fastening surface 631 is a surface that comes into contact with the fastening surface 512 (see FIG. 4) of the bracket 5 when the fuel accumulator 6 is fastened to the bracket 5 using the first fastening member 62.

The injector 7 (not shown in FIG. 9) is inserted into the insertion hole 66 of the fuel accumulator 6 and is directly connected to the fuel accumulator 6. The end of the injector 7 is inserted and held liquid-tight in the insertion hole 66 by, for example, an O-ring attached to the injector 7. This allows the injector 7 to inject fuel supplied through the insertion hole 66 of the fuel accumulator 6 into the combustion chamber 215. A positioning surface 661 is provided around the insertion hole 66. The positioning surface 661 is a surface that comes into contact with a biasing member 72 attached to the injector 7 and determines the position of the injector 7.

As shown in FIG. 9, the fastening surface 631 formed around the hole 63 is flush with the positioning surface 661 formed around the insertion hole 66. This allows the fuel injection system 3 according to this embodiment to be easily assembled and to be more efficient to assemble, while also allowing the fuel accumulator 6, to which the injector 7 is directly connected, to be stably fixed to the bracket 5.

The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the claims. The configurations of the above embodiment can be partially omitted or arbitrarily combined in a different way than described above.

2: engine, 3: fuel injection system, 5: bracket, 6: fuel accumulator, 7: injector, 8: harness, 21: cylinder head, 22: head cover,
23: Intake manifold, 51: First fixing portion, 52: Second fixing portion, 53: Third fixing portion, 59: Second fastening member, 61: Fuel pipe, 62: First fastening member, 63: Hole, 64: Convex portion, 66: Insertion hole, 71: Positioning surface, 72: Urging member, 81: Connection portion, 82: Retaining member, 211: Sleeve, 212: Insertion hole, 213: Female thread, 214: Positioning surface, 215: Combustion chamber, 216: Mounting surface, 511: Female thread, 512: Fastening surface, 513: Recess, 521: Hole, 531: Hole, 541: First reinforcing portion, 542: Second reinforcing portion, 543: Third reinforcing portion, 631: Fastening surface, 641: Tip portion, 661: Positioning surface, 821: protrusion, A1: arrangement direction, D1, D2: distance

Claims (5)

A fuel injection system for injecting fuel into a combustion chamber of an engine, comprising:
a bracket fixed to a cylinder head of the engine;
a fuel accumulator that is supported and fixed to the bracket by a first fastening member and that accumulates the fuel supplied from a fuel pump under pressure;
an injector directly connected to the fuel accumulator and attached to the cylinder head, the injector injecting the fuel supplied from the fuel accumulator into the combustion chamber;
Equipped with
At least one of the fuel accumulator and the bracket has a guide member that guides the injector to an installation position of the cylinder head,
The bracket is fixed to the cylinder head using a second fastening member,
A first fixing portion that engages with the first fastening member;
a second fixing portion having a hole through which the second fastening member passes;
a reinforcing portion that connects and reinforces the first fixing portion and the second fixing portion that are adjacent to each other;
and formed in a ladder or lattice shape,
2. A fuel injection system according to claim 1, wherein the injector is attached to the cylinder head through a gap in the bracket formed in the ladder shape or the lattice shape . The guide member is
a protrusion provided on one of the fuel accumulator and the bracket;
a recess provided in the other of the fuel accumulator and the bracket, into which the protrusion fits;
2. The fuel injection system of claim 1, further comprising: The injector is attached to the cylinder head by being inserted into an insertion hole formed in the cylinder head,
3. The fuel injection system according to claim 2 , wherein a direction in which the protrusion fits into the recess is parallel to a direction in which the injector is inserted into the insertion hole. 4. The fuel injection system according to claim 2 , wherein the guide member has a plurality of the protrusions and a plurality of the recesses into which the protrusions fit, respectively . 5. The fuel injection system according to claim 2 , wherein when the injector is attached to the cylinder head, the protrusion begins to fit into the recess before the position of the injector relative to the cylinder head is determined.

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