WO2003095824A1

WO2003095824A1 - Fuel pump mounting structure of fuel injection engine

Info

Publication number: WO2003095824A1
Application number: PCT/JP2003/005800
Authority: WO
Inventors: Shinichi Kurosawa
Original assignee: Yamaha Hatsudoki Kabushi Kikaisha
Priority date: 2002-05-10
Filing date: 2003-05-08
Publication date: 2003-11-20
Also published as: JP2004028079A; JP4139693B2

Abstract

A fuel pump mounting structure of a fuel injection engine capable of driving a fuel pump (41) for supplying fuel to a fuel injection valve (40) by a camshaft (8) through a cam, wherein the fuel pump (41) is passed through a mounting hole (3d) formed in a head cover (3) and fixed to the cam carrier (11) of a cylinder head (2) through a bracket (42).

Description

Description Fuel injection engine mounting structure for fuel injection engine

The present invention relates to a fuel pump mounting structure for a fuel injection engine in which a fuel pump for supplying fuel to a fuel injection valve is cam-driven by a cam shaft. Background art

For example, in an in-cylinder fuel injection type four-cycle engine in which fuel is directly injected and supplied into a cylinder, a fuel pump that supplies high-pressure fuel to a fuel injection valve may be driven by a camshaft.

Conventionally, as a mounting structure of such a fuel pump, conventionally, for example, a mounting hole is formed in a portion facing a cam shaft of a head cover, a driving portion of the fuel pump is inserted into the mounting hole, and a flange portion of the fuel pump is mounted on the head cover. Some are fixed. In this conventional structure, the wall thickness of the pump mounting portion of the head cover is increased in order to increase the mounting strength of the fuel pump.

However, when the fuel pump is mounted on the head cover as in the above-described conventional structure, the vibration of the fuel pump is easily transmitted to the head cover, which may cause noise. In order to suppress such noise, it is effective to further increase the thickness of the head cover at the pump mounting portion, but this is disadvantageous in terms of cost and weight.

When the above-mentioned structure in which the fuel pump is mounted on the head cover is adopted, since the cam shaft is mounted on the cylinder head, the fuel pump on the head force cover side and the cam on the cylinder head side There is a problem that alignment with the axis is difficult. The present invention has been made in view of the above-described conventional circumstances, and has been made in consideration of the noise generated by a fuel pump. An object of the present invention is to provide a fuel injection engine mounting structure for a fuel injection engine, which can prevent the occurrence of the occurrence and can easily perform alignment with a camshaft. Disclosure of the invention

According to a first aspect of the present invention, in a fuel pump mounting structure for a fuel injection engine in which a fuel pump for supplying fuel to a fuel injection valve is driven by a camshaft, the fuel pump is formed on a head cover. It is characterized by being fixed to the cylinder head through the through hole.

The invention according to claim 2 is the invention according to claim 1, wherein the fuel pump is fixed to a cylinder head via a bracket, and the bracket has a through hole through which a driving unit of the fuel pump is attached. And a base portion formed so as to straddle a cam cap adjacent in the axial direction of the cam shaft. The base portion is shared with the cam carrier of the cylinder head together with the cam cap. It is characterized by being fastened and fixed.

The invention according to claim 3 is the invention according to claim 2, wherein the main body of the bracket is exposed to the outside from the through hole of the head cover, and a gap between the peripheral portion of the through hole and the main body is provided. Is provided with a seal member made of an elastic body. According to a fourth aspect of the present invention, in any one of the first to third aspects, the fuel pump is disposed so as to be inclined outward with respect to the cylinder axis. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of a cylinder head of an engine according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the cylinder head (a cross-sectional view taken along line 11 in FIG. 1). Fig. 3 is a cross-sectional view of the above-mentioned cylinder head (a cross-sectional view taken along line II-III in Fig. 1). FIG. 4 is a sectional view showing the operation of the variable valve lift mechanism of the engine. FIG. 5 is a cross-sectional view (a cross-sectional view taken along the line V-V in FIG. 1) of a mounting portion of the fuel pump of the engine.

FIG. 6 is a side view of the fuel pump mounting portion.

FIG. 7 is a plan view of a bracket for mounting the fuel pump.

FIG. 8 is a side view of the bracket.

FIG. 9 is a cross-sectional view (a cross-sectional view taken along line IX-IX in FIG. 7) of the bracket of the bracket.

FIG. 10 is a cross-sectional view (cross-sectional view taken along line X-X) of the bracket.

FIG. 11 is a cross-sectional view of a valve spring supporting portion of the cylinder head. FIG. 12 is a diagram of the rocker arm of the engine. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 12 are views for explaining a fuel pump mounting structure of a fuel injection type engine according to one embodiment of the present invention. FIG. 1 is a plan view of a cylinder head of the engine, and FIGS. Fig. 3 is a cross-sectional view of the cylinder head (cross-sectional view taken along the line Π-Ι ， in Fig. 1; Fig. 4 is a cross-sectional view showing the operation of the variable valve lift mechanism). 5 is a cross-sectional view of the fuel pump mounting part (cross-sectional view taken along the line VV in FIG. 1), FIG. 6 is a side view of the fuel pump mounting part, and FIGS. 7 and 8 are plan, side, and figure views of the bracket. 9, Fig. 10 is a cross-sectional view of the bracket (cross-sectional view taken along line IX-IX and XX in Fig. 7), Fig. 11 is a cross-sectional view of the intake port of the cylinder head, and Fig. 12 is a rocker arm. FIG.

In the figure, reference numeral 1 denotes a water-cooled 4-cycle multi-cylinder engine. The engine 1 opens and closes intake and exhaust valves 4 and 5 via rocker arms 7 and 9 by intake and exhaust camshafts 6 and 8 described later. A driving valve mechanism, a variable valve lift mechanism that variably controls lift amounts of intake and exhaust valves 4 and 5 according to an engine operating state, and a cylinder that directly injects fuel into a cylinder by a fuel injection valve 40. With internal fuel injection device You.

The upper mating surface 1a of the cylinder head 2 of the engine 1 is connected to the lower mating surface 3a of the head cover 3, and the lower mating surface 1b is connected to a cylinder block (not shown). A crankcase (not shown) for accommodating a crankshaft is connected to the cylinder block. Reference numeral 12 denotes a head bolt hole for fixing the cylinder head 2 to the cylinder block, and two holes are formed between the cylinders.

A combustion recess 2c is formed in the lower mating surface 2b of the cylinder head 2, and the combustion recess 2c, the cylinder bore of the cylinder block, and the top surface of the piston inserted into the cylinder bore are formed. (Not shown) A space surrounded by and is a combustion chamber.

The combustion recess 2c has two intake openings 2d, 2d and two exhaust openings 2e, 2e. The intake opening 2d, the exhaust opening 2e have an intake valve 4, an exhaust valve 2e, respectively. Valve 5 is provided so as to be openable and closable. Each intake valve 4 is driven to open and close by an intake force arm 7 by an intake force shaft 6 constituting the valve operating mechanism, and each exhaust valve 5 is driven by an exhaust cam shaft 8 via an exhaust port arm 9. It is driven to open and close. The intake and exhaust camshafts 6, 8 are rotationally driven by a crankshaft via a timing chain (not shown).

An intake port 1 f communicating with each intake opening 2 d is formed in the cylinder head 1, and each intake port 1 f joins on the way and leads to the right wall surface 2 f ′ of the cylinder head 2. Have been. An exhaust port 1 g communicating with each exhaust opening 2 e is formed in the cylinder head 2, and each exhaust port 1 g joins on the way and is led out to the left wall surface 2 g ′. The intake port 2 f is formed upright so that the port axis f forms an angle of about 50 degrees with respect to the cylinder axis A, while the exhaust port 2 g has the port axis g with respect to the cylinder axis A. And is formed so as to form a substantially right angle.

The intake and exhaust camshafts 6 and 8 are provided with the variable valve lift mechanism. FIG. 4 shows the intake side of the variable valve lift mechanism, and since the exhaust side has substantially the same structure, only the intake side will be described. The variable valve lift mechanism includes a low-speed cam nose 6a and a high-speed cam nose 6b formed on the intake camshaft 6, an independently rotatable low-speed rocker arm 7a and a high-speed rocker arm 7b, And the high-speed rocker arm 7b can be idled or interlocked with the low-speed rocker arm 7a. And a hydraulic cylinder 21 having pistons 21a and 21a for driving the engaging pins 20 forward and backward.

In the low-speed operation range, the rotation of the camshaft 6 is transmitted only to the low-speed rocker arm 7a, and the lift amount of the intake valve 4 is small (see the right side of the cylinder axis A in FIG. 4). In the high-speed operation range, the engagement pin 20 is engaged with the high-speed rocker arm 7 b by the hydraulic pressure supplied to the oil chamber 21 b of the cylinder section 21, and the rotation of the cam shaft 6 is transmitted to the high-speed rocker arm 7 b. This increases the lift of the intake valve 4 (see the left side of the cylinder axis A in FIG. 4).

The in-cylinder fuel injection device includes a fuel injection valve 40 for injecting fuel into each cylinder, and a fuel pump 41 for supplying high-pressure fuel to each fuel injection valve 40. The fuel injection valve 40 is positioned vertically below the two intake boats 2 f of the cylinder head 2 and is inclined so as to be substantially parallel to the port axis f of the intake port 2 f. The injection port 40a of the fuel injection valve 40 faces the center of the combustion chamber.

The cylinder head 2 includes a head body 10 in which the intake and exhaust ports 2 f and 2 g are formed, and a cam in which the intake and exhaust cam shafts 6 and 8 and the rocker arms 7 and 9 are arranged. The carrier 11 is divided into a carrier 11 and a lower surface 11 f of the force carrier 11 is placed on the receiving surface 10 f of the head body 10. The cam carrier 11 is a cam port described later. The bolts 43 are connected to the head body 10 together with the cam caps 15 and 16 by bolts.

An outer peripheral wall 10a is formed on the head main body 10 so as to surround the outer peripheral portion of the cam carrier 11. This head is attached to the upper mating surface 2a of this outer peripheral wall 10a. The lower mating surface 3a of the cover 3 is mounted and fixed with an oil seal 13 interposed therebetween, whereby an oil-tight cam chamber 14 is formed.

The cam carrier 11 extends in the direction perpendicular to the camshaft so as to cross the cylinder axis A, and one journal receiving portion 11a per cylinder and a lateral wall portion 11c extending between the cylinders and extending in the direction perpendicular to the camshaft. And a vertical wall portion 11b that extends in the cam axis direction and connects the adjacent journal receiving portion 11a and the horizontal wall portion 11c.

The intake-side and exhaust-side cam caps 15 and 16 are attached to the intake-side upper mating surface 11d and the exhaust-side upper mating surface 11e of each of the journal receiving portions 11a. An intake-side cam journal receiving hole 17 is formed between each intake-side upper mating surface 11 d and a lower-side mating surface 15 a of the intake-side cam cap 15, and each cam journal receiving hole 17 is formed. Thereby, the journal portion of the suction cam shaft 6 is rotatably supported. An exhaust-side cam journal receiving hole 18 is formed between the exhaust-side upper mating surface 1 1 e and the lower-side mating surface 16 a of the exhaust-side cam cap 16. The journal of camshaft 8 is rotatably supported.

A plug hole 23 penetrating through the head body 10 and communicating with the combustion recess 2c is formed in a portion of each of the journal receiving portions 11a facing the cylinder axis A. An ignition plug 24 is inserted into the plug hole 23, and the ignition plug 24 is detachably attached to the head body 10 so that an electrode portion of the ignition plug 24 is located in the combustion recess 2c. ing . The plug center line B of the plug hole 23 is formed so as to be slightly deviated from the cylinder axis A toward the exhaust side.

A plug pipe 25 is inserted into the plug hole 23, and a lower end 25 a of the plug pipe 25 is press-fitted and fixed in a plug hole 23 a of the head body 10. The upper end 25b of the plug pipe 25 projects outside through a pipe hole 3b formed in the head cover 3, and an oil-tight space is formed between the pipe hole 3b and the plug pipe 25. Sealed to. As a result, the inside of the plug pipe 25 and the cam chamber 14 are defined, and the replacement of the spark plug 24 can be performed without removing the head cover 3. It is becoming possible to obtain. At the outer end of the plug pipe 25, the spark plug

An ignition coil 26 connected to the terminal electrode 24 is detachably mounted.

A concave portion 10b is formed on both sides of the journal receiving portion 11a of the receiving surface 10f of the head body 10 described above. At the bottom of the concave portion 1Ob, intake and exhaust side valve seat portions 10c and 10d are bulged and formed. Each of the valve seat portions 10c and 10d has an intake and exhaust port. Valve guide holes 10 g and 10 g communicating with 2 f and 2 g are formed. The valve shafts 4a and 5a of the intake and exhaust valves 4 and 5 are slidably inserted into the valve guide member 30 press-fitted into the respective valve guide holes 10g. Valve parts 4b and 5b for opening and closing the intake and exhaust openings 2d and 2e are formed at the lower ends of the valve shafts 4a and 5a, and the rockers are provided at the upper ends via valve chips 3 and 31. Rooms 7 and 9 are in contact. Spring retainers 32, 33 are fixed to the upper ends of the intake and exhaust valve shafts 4a, 5a by taper fitting.

The valve spring support structure of the present embodiment will be described.

An exhaust spring receiving seat 1Oh is formed on the periphery of the valve guide hole 10g of the exhaust side valve seat 10d. An exhaust knob spring 35 is disposed between the spring seat 10h and the exhaust side spring retainer 33, and the exhaust valve 5 is urged in the closing direction by the valve spring 35. .

Inner and outer intake spring receiving seats 10j and 10k are formed at the periphery of the valve guide hole 10g of the intake side valve seat portion 10c. An inner spring 36 is provided between the inner positioning portion 3 2a of the intake-side spring retainer 32 and an outer spring receiving seat 10k and the outer positioning portion 3 2b of the spring retainer 32 are provided. An outer spring 37 shorter than the spring length of the inner spring 36 is coaxially disposed between the springs 36 and 36.

The intake valve 4 is urged in the closing direction by 3 7.

Here, the inner spring seat 10 j is located lower than the outer spring seat 10 k. It is formed in the shape of a step. As a result, the spring length of the inner spring 36 is longer than the spring length of the outer spring 37, in other words, the outer spring 37 is shortened while ensuring the required set load 最大 maximum load during lift. . Since the inner and outer spring seats 10j and 10k are simultaneously processed by the cutting tool corresponding to the step, the number of processing steps does not increase.

According to the valve spring support structure of the present embodiment, the inner spring receiving seat 10j of the intake side valve seat portion 10c is formed in a stepped shape so as to be located lower than the outer spring receiving seat 10k. Therefore, while lowering the position of the intake-side spring retainer 32, the necessary spring length of the inner spring 36 can be secured, and the cylinder axial dimension of the cylinder head 2 can be reduced.

Further, in the present embodiment, the required set load and maximum load can be secured while forming the outer spring seat 10 k at a high place, so that the fuel injection valve is provided below the intake port 2 f of the cylinder head 2. Even when 40 is arranged, it is possible to suppress an increase in the height of the cylinder head 2. That is, when the fuel injection valve 40 is arranged below the intake port 1f, a bulging portion for securing a space for arranging the fuel injection valve 40 easily swells on the inner surface of the intake port, which is avoided. To do this, it is necessary to raise the intake port 2 f. Accordingly, it is necessary to arrange the spring seat for the intake valve 4 at a high place to secure the necessary port wall thickness, and to secure the required spring length, the position of the spring retainer 32 must be increased. As a result, the height of the cylinder head becomes large.

In the present embodiment, the spring length of the inner spring 36 can be increased, so that the length of the outer spring 37 is short, and it is not necessary to raise the position of the spring retainer 32. As a result, the cylinder head An increase in the height dimension of 2 can be suppressed.

Next, the rocker shaft arrangement structure will be described.

The cam carrier 11 passes through the intake and exhaust port cap shafts 50, 51 extending in parallel with the cam shafts 6, 8 so as to penetrate the journal receiving portion 11a and the lateral wall portion 11c. ing. The rocker shafts 50 and 51 are the same as those of the cam carrier 11 above. Locking screws (fixing means) 52 screwed to the horizontal wall portion 11c located between the cylinders are positioned and fixed so that they cannot rotate. The rocker shafts 50, 51 rotatably support the intake / exhaust port intake arms 7, 9, respectively.

The intake and exhaust side rocking shafts 50 and 51 are disposed inside the intake and exhaust valves 4 and 5, respectively. The intake and exhaust side rocker shafts 50 and 51 are arranged symmetrically with respect to the Bragg center line B deviated from the cylinder axis A to the exhaust side. As a result, the intake side rocker shaft 50 and the cylinder are aligned with each other. The distance from the axis A is smaller than the distance between the exhaust side rocker shaft 51 and the cylinder axis A.

Each of the intake and exhaust side rocker shafts 50 and 51 is disposed near the plug axis B such that the inner half thereof overlaps the plug pipe 25 when viewed in the camshaft direction. Escape recesses 50a and 51a are formed in the overlapping portions of the rocker shafts 50 and 51 with the plug pipe 25. These escape recesses 50 a and 51 a are cut out along the outer peripheral surface of the plug pipe 25 so as to form an arc shape in plan view.

In the present embodiment, the rocker arm and the like are assembled according to the following procedure. Rocker arms 7, 9 are located on both sides of the journal receiving portion 11a of the cam carrier 11, and the rocker shaft 50 is positioned so that the collars 50b, 51b are located between them and the side wall portion 11c. , 51, the locking force shafts 50, 51 are released, and the concave portions 50 &, 5 la are rotated so as to face the cylinder center side, and locked with the lock screw 52. Then, this assembly is mounted on the receiving surface 10 f of the head body 10 so that the escape recesses 50 a and 51 a do not interfere with the plug pipe 25, and the camshafts 6 and 8 are mounted. Set, attach the cam caps 15 and 16, and fix them together with the cam bolts 43.

In this way, the cam carrier 11 can be detached from the head body 10, and the externally mounted power shafts 50, 51 and rocker arms 7, 9 can be attached to the head body 10 before mounting. As a result, assembly workability can be improved.

In addition, the rocker shafts 50 and 51 escape to form recesses 50 a and 51 a, respectively. Since the lock screw 52 is fixed to the angular position corresponding to 5, the work of mounting the cam carrier 11 to the head body 10 can be easily performed.

According to the present embodiment, the intake and exhaust side rocker shafts 50 and 51 are arranged such that the inner halves overlap the plug pipe 25 when viewed in the camshaft direction. Since relief recesses 50a, 51a are formed in the overlapping portion of the 51 with the Bragg pipe 15, each rocker shaft 50, 51 is connected to the cylinder axis A by the clearance recesses 50a, 51a. The valve can be placed closer to the side, and the valve pinch angle can be reduced accordingly. As a result, the shape of the combustion chamber can be improved and the entire engine can be made more compact.

Since each of the above-mentioned rocking shafts 50 and 51 can be brought closer to the cylinder axis A side, the rising angle of the intake port 2 f can be increased, and therefore, the intake port 2 f of the cylinder head 1 can be increased. In the case where the fuel injection valve 40 is arranged below the fuel injection valve 40, the swelling of the inner surface of the intake passage for securing a space for disposing the fuel injection valve 40 can be eliminated, and the intake resistance can be reduced.

The suction arms 7 and 9 on the intake and exhaust sides are respectively provided with bases 7 (1 and 9d having support holes 7c and 9 (through which the shafts 50 and 51 are passed) and bases 7d and The arm tip 7 e, 9 e extends outwardly following 9 d, and the valve tip 31 is in contact with the lower surface of the tip of the arm section 7 e, 9 e. The tip of 9e is formed to be thick in the valve opening and closing direction, and pin holes 7g and 9g are formed in the thick portions 7f and 9f, into which the above-described engagement pins 20 are inserted. Have been.

On the upper surfaces of the arm portions 7e and 9e, there are formed slit 面 'surfaces 7h and 9h on which the cam nose of each cam shaft 6 and 8 slides. Each of the slipper surfaces 7h, 9h has an arc shape with a radius R as shown in Fig. 12, and the bases 7d, 9h are within a circle r extending from the slipper surfaces 7h, 9h. d and the arm portions 7e and 9e are located. The slipper surfaces 7 h and 9 h are formed by performing a polishing process by rotating a polishing blade (not shown) along the circle r. According to this embodiment, the slipper surfaces 7 h and 9 h of the intake and exhaust side rocker arms 7 and 9 are formed into an arc shape having a radius R, and the base is formed inside a circle r formed by extending the slipper surfaces 7 h and 9 h. Since the 7d, 9d and the arm portions 7e, 9e are located, the polishing tool can be rotated and moved along the circle r, and the desired surface roughness and processing accuracy can be obtained. Polishing can be performed in a short time, and the processing cost can be reduced. That is, as shown by the two-dot chain line in FIG. 12, when the base 9 d ′ is positioned outside the circle r, for example, if the cutting tool is moved along the circle r, it interferes with the base 9 d ′. You. For this reason, the grinding process is performed by moving the cutting tool in a direction perpendicular to the paper surface, which causes a problem that processing accuracy is low and time is required.

Next, the mounting structure of the above-described fuel pump 41 will be described.

The fuel pump 41 includes a pump body 41 a having a fuel suction port and a discharge port (not shown), a driving section 41 b having a plunger 41 c, the driving section 41 b and the pump body 41 a The plunger 41c is reciprocatingly driven to pressurize the fuel, thereby forming a fuel supply pipe and a fuel rail (not shown). The fuel is fed to each of the fuel injection valves 40 through the above.

The fuel pump 41 is disposed above the exhaust camshaft 8 between the two cylinders, and the plunger 41c is provided on the exhaust camshaft 8 at three cam nozzles 8a formed at intervals of 120 degrees. Driven by

The fuel pump 41 is mounted and fixed to the cam carrier 11 of the cylinder head 2 via a bracket 42 through a mounting hole 3 d formed in the top wall of the head cover 3. I have.

The bracket 42 is made of aluminum die-cast, and is adjacent to the main body 42 b having the mounting hole 42 a to which the driving part 41 b is mounted, and the exhaust camshaft 8. A base portion 42 c having a rectangular shape in plan view formed so as to straddle the cam caps 16, 16 which are fitted with each other. A bolt hole 4 2 d is formed in each corner of the base portion 42 c. Is shaped Has been established. The base portion 42c is fixed to the cam carrier 11 together with the cam caps 16 by the cam bolts 43 inserted into the bolt holes 42d.

The main body portion 4 2b has a substantially rhombic shape in plan view, and has a large-diameter portion 4 2e facing the peripheral portion of the mounting hole 3d on the lower surface of the head cover 3 with a slight gap therebetween. The small-diameter portion 42 f projects from the mounting hole 3 d to the outside of the head cover 3, and fixing bolts 44, 44 are implanted at both ends of the small-diameter portion 42 f. A relief recess 42b 'for preventing contact with the camshaft 8 is provided on the lower surface of the main body 42b.

A circumferential groove 42g is formed on the outer peripheral portion of the large diameter portion 42e. A rubber seal member 45 is mounted in the peripheral groove 42g, and the rubber seal member 45 is in contact with the peripheral portion of the mounting hole 3d. As a result, the space between the mounting hole 3 d and the bracket 42 is oil-tightly sealed.

Then, the fuel pump 41 has a mounting flange portion 41 d which has a small-diameter portion 42 f of the bracket 42 with a gasket 46 interposed therebetween, and is fixed to the bracket 4 by fixing bolts 44 and nuts 47. Fixed to 2. The fuel pump 41 is arranged obliquely such that its axis A1 is inclined outward with respect to the cylinder axis A (see FIG. 5). The gasket 46 is formed by arranging a thin metal plate on both surfaces of a resin member, whereby the fuel pump 41 and the bracket 4 are oil-tightly sealed.

According to the fuel pump mounting structure of the present embodiment, since the fuel pump 41 is directly fixed to the cam carrier 11 of the cylinder head 2 via the brackets 4 • 2, the fuel carrier 4 1 having high strength and rigidity is provided with fuel. The pump 41 can be fixed, and the generation of noise due to the vibration of the fuel pump 41 can be suppressed as compared with the case where the pump 41 is fixed to the conventional head cover. In addition, since only bracket 4 needs to be added, the increase in cost can be suppressed. In the present embodiment, the fuel pump 41 is connected to the cam carrier 11 The fuel pump 41 and the camshaft 8 can be easily and reliably aligned.

In the present embodiment, the bracket 42 is composed of a main body 42 b to which the driving part 41 b of the fuel pump 41 is attached and a base part 42 c, and the base part 42 c Since the cam caps 16 and 16 together with the adjacent cam caps 16 and 16 are fixed together by the cam bolts 43, the mounting strength of the fuel pump 41 can be increased and the position with the cam shaft 8 can be improved. The alignment can be performed easily and reliably. In addition, since the cam bolt 43 for fastening the cam cap 16 to the cam carrier 11 is shared, an increase in the number of parts can be suppressed.

In the present embodiment, a large-diameter portion 4 2 e opposing the main body portion 4 2 b with a gap in a peripheral portion of the mounting hole 3 d of the head cover 3, and a small-diameter portion protruding outward from the mounting hole 3 d. Since the rubber seal member 45 attached the rubber seal member 45 to the large-diameter portion 42e, the vibration of the fuel pump 41 was covered by the rubber seal member 45. The transmission of the noise can be suppressed, and the generation of noise can be more reliably prevented.

Further, since the small-diameter portion 42 f projects outward from the head cover 3, the fuel pump 41 can be retrofitted after the engine unit is assembled, and the assemblability can be improved. .

In the present embodiment, since the fuel pump 41 is arranged so that its axis A1 is directed outward with respect to the cylinder axis A, the wiring of the spark plug 24 and the fuel and fuel above the head cover 3 are arranged. A space for arranging fuel pipes and the like to the injection valve 40 can be secured. Industrial applicability

According to the mounting structure according to the first aspect of the present invention, the fuel pump is directly fixed to the high-strength and rigid cylinder head, so that the noise caused by the vibration of the fuel pump is lower than when the fuel pump is fixed to the conventional head cover. Generation can be suppressed. Also attached to cylinder head It is only necessary to form a boss portion or add a bracket, thereby suppressing an increase in cost.

In the present invention, since the structure in which the fuel pump is mounted on the cylinder head to which the camshaft is mounted is adopted, the positioning between the fuel pump and the camshaft can be performed easily and accurately.

According to the second aspect of the present invention, a bracket including a main body and a base to which the driving unit of the fuel pump is attached is interposed, and the base is jointly fastened to the cam carrier together with the adjacent cam cap. Since the fuel pump is fixed, the mounting strength of the fuel pump can be increased, the positioning with the camshaft can be performed easily and reliably, and the cam port that fastens the cam cap to the cylinder head can be shared. The increase can be suppressed.

According to the third aspect of the present invention, the main body of the bracket is exposed to the outside through the through hole of the head cover, and an elastic seal member is provided between the peripheral portion of the through hole and the main body. With the seal member, the bracket and the head cover can be sealed oil-tight, and the vibration of the fuel pump can be suppressed from transmitting to the head cover. Can be prevented.

In addition, since the main body is projected outward from the head cover, the fuel pump can be retrofitted to the main body after the engine unit is assembled, so that the assemblability can be improved.

According to the fourth aspect of the invention, the fuel pump is inclined outward with respect to the cylinder axis, so that a wiring space for a spark plug wiring, a fuel pipe, and the like can be secured above the head cover.

Claims

The scope of the claims

1. In a fuel pump mounting structure of a fuel injection engine in which a fuel pump for supplying fuel to a fuel injection valve is cam-driven by a cam shaft, a fuel pump is provided with a through hole formed in a head cover. The fuel injection engine has a fuel pump mounting structure that is fixed to the cylinder head through the cylinder.

2. The fuel pump according to claim 1, wherein the fuel pump is fixed to a cylinder head via a bracket, and the bracket is connected to a main body having a through-hole through which a driving unit of the fuel pump is attached. A base portion formed so as to straddle a cam cap adjacent in the axial direction of the cam shaft, and the base portion is fixed together with the force cap to a cam carrier of a cylinder head. A fuel pump mounting structure for a fuel injection engine.

3. In claim 2, the main body of the bracket is exposed to the outside through the through hole of the head cover, and an elastic body is provided between a peripheral portion of the through hole and the main body. A fuel pump mounting structure for a fuel injection engine, wherein a seal member is provided.

4. The fuel pump mounting structure for a fuel injection engine according to any one of claims 1 to 3, wherein the fuel pump is arranged to be inclined outward with respect to a cylinder axis.