JPH11324865A - Direct-injection-type multi-cylinder diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid interference of intake/exhaust ports and various members arranged around a cylinder bore with a member for fixing a fuel injection nozzle, relatively simplify a structure, and fix the fuel injection nozzle to a cylinder head with an adequate pressing force, in a direct-injection-type diesel engine. SOLUTION: The engine has locking portions 51 for respectively locking shoulder portions of both fuel injection nozzles 25 of adjacent cylinders at its both ends, a mounting member 50 having a fastening member through hole 53 in its central part, and a fastening member 60 penetrated through the fastening member through hole 53 of this mounting member 50. A boss portion 43 having a screw hole 44 is formed in a cylinder head 3, and the fastening member 60 comprises a bolt which has a fastening male screw portion 61 and a seating portion 63 having an expanded cross section at its bottom part, an abutting portion 64 to the upper surface of the mounting member 50 at its top portion, and a small cross sectional portion 66 at its intermediate part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type multi-cylinder diesel engine in which a fuel injection nozzle is provided for each cylinder so as to face a cylinder bore from above in the axial direction of the cylinder. The present invention relates to a structure for fixing a fuel injection nozzle.

[0002]

2. Description of the Related Art Conventionally, a direct injection type multi-cylinder diesel engine in which a fuel injection nozzle is provided for each cylinder so as to face a cylinder bore from above in the axial direction of the cylinder is generally known. In this diesel engine, it is necessary to fix the fuel injection nozzle in a predetermined state above the cylinder bore in the cylinder axis direction, but the structure of the intake and exhaust ports around the cylinder bore, the valve train, etc. is increased by increasing the number of intake and exhaust valves. When it becomes complicated, it is necessary to devise the structure and arrangement of the members for fixing the fuel injection nozzle in order to avoid interference with them.

In consideration of such a point, for example, Japanese Patent Application Laid-Open No. 8-326511 discloses that each cylinder is provided with two intake valves and two exhaust valves, and these cylinders are provided with a single camshaft rocker. In a diesel engine engine that is driven through an arm,
A fuel injection nozzle is disposed above the cylinder bore in the cylinder axis direction, and a nozzle pressing member is disposed at a position between the intake valve shaft and the exhaust valve shaft on a side opposite to the camshaft side with respect to the fuel injection nozzle. A structure is shown in which the nozzle holding member is fixed to the cylinder head with bolts in a state where the intermediate portion of the fuel injection nozzle is locked to the fork-shaped portion at the tip of the nozzle holding member.

[0004]

In the structure disclosed in the above publication, the nozzle holding member is arranged by utilizing the space between the intake valve shaft and the exhaust valve shaft (between the intake port and the exhaust port). However, when the structure around the cylinder bore is changed, it may be difficult to arrange the nozzle pressing member in such an arrangement. For example, as a structure provided with a glow plug for promoting start-up at the time of extremely cold, a plug mounting portion may be provided between an intake port and an exhaust port. In some cases, a space for disposing the nozzle holding member or a bolt for fixing the nozzle holding member to the cylinder head may not be obtained.

In view of such circumstances, the present invention avoids interference between intake / exhaust ports and various members provided around the cylinder bore and members for fixing the fuel injection nozzle, and also makes the structure relatively simple. It is another object of the present invention to provide a direct-injection multi-cylinder diesel engine capable of fixing a fuel injection nozzle to a cylinder head with an appropriate pressing force.

[0006]

In order to achieve the above object, the present invention provides a direct injection type multi-cylinder diesel engine in which a fuel injection nozzle is provided for each cylinder so as to face the cylinder bore from above in the cylinder axis direction. The engine has a locking portion at both ends for locking the shoulders of both fuel injection nozzles of adjacent cylinders, and has a fastening member insertion hole at the center, and is installed over the two fuel injection nozzles. And a rod-shaped fastening member that is inserted into the fastening member insertion hole of the installation member and whose upper and lower ends are connected to the installation member and the cylinder head, and that a lower end of the fastening member is connected to the cylinder head. A corresponding fastening screw portion and a facing portion for seating are provided at a portion or a joining portion between an upper end portion of the fastening member and the joining member on the erection member side. A small cross-section having a smaller cross-sectional area than the both ends is formed at the intermediate portion, and the corresponding fastening screw portion is screwed into the middle portion and tightened until the facing portion for seating comes into contact with the screw portion. The small cross section of the fastening member is elastically extended to generate a predetermined restoring force, and this restoring force acts as a pressing force on the two fuel injection nozzles via the bridging member.

[0007] According to this configuration, the mounting member is bridged between the two fuel injection nozzles of the adjacent cylinders.
Since the fastening member is located in the middle of the adjacent cylinder, the fuel injection nozzle is fixed while avoiding interference between these members and various members around the cylinder bore.
Then, the fuel injection nozzle is fixed with a corresponding force by elastic deformation of the small cross-section as the fastening member is tightened. In this case, the seating facing portion abuts and the fastening is performed. The elastic deformation of the member and the corresponding force are appropriately regulated, so that the pressing force acting on the fuel injection nozzle and the force acting on the cylinder head from the joint between the fastening member and the cylinder head are prevented from becoming excessive.

In the present invention, it is preferable that the diameter of the small cross section of the fastening member is equal to or smaller than the diameter of the fastening screw portion. In this case, the strength of the fastening screw portion is secured while the fastening is performed. Accordingly, the small cross section elastically deforms relatively easily.

The fastening member is, for example, a bolt.
In this case, a boss portion having a female screw portion for fastening is formed at a fastening member connecting portion of the cylinder head, and the fastening member has a male screw portion for fastening at a lower end portion and a cross-sectional area from the male screw portion for fastening. It has a seating portion that is enlarged to face the seating surface at the upper end of the boss portion, and has a contact portion at the upper end portion with the upper surface of the erection member, and the contact portion and the seating portion It is formed so as to have a small cross section between them. The vertical distance (L) from the nozzle seating position where the vicinity of the tip of the fuel injection nozzle is seated to the cylinder head to the nozzle locking position where the locking portion of the bridge member abuts the shoulder of the fuel injection nozzle.
1), the vertical distance (L2) from the nozzle seating position to the upper end seating surface of the boss, and the vertical distance from the seating portion to the locking position in a state where the fastening member is not elastically deformed. The relationship with the direction distance (L3) is [L1> L2 +
L3].

In this case, the fastening member made of a bolt is fastened to the boss portion of the cylinder head, and the small cross-section portion is appropriately elastically deformed by the fastening, so that a corresponding force acts on the fuel injection nozzle. I do.

Preferably, the boss portion having the female screw portion for fastening projects upward from the deck of the cylinder head, and a water jacket is preferably formed below the deck in the cylinder head. The cooling water circulation part of the jacket is not restricted, and the force acting on the cylinder head side from the female screw part to be tightened with the tightening is absorbed by the boss part to some extent, and the force applied to the deck is reduced. Is done.

In the case of such a structure, the head cover abutment surface provided in the peripheral portion of the cylinder head and the upper surface of the boss having the female screw portion for fastening are formed on the same surface. In this case, the upper surface of the boss portion can be processed at the same time when the head cover abutment surface is processed. Then, the dimensional accuracy of the bearing surface at the upper end of the boss portion is enhanced by this processing.

When the cylinder head is made of an aluminum alloy and the bridge member and the fastening member are made of steel, a washer is interposed between a seating surface at an upper end of a boss portion of the cylinder head and a seating portion of the fastening member. In this case, it is preferable to prevent the boss from being deformed when the fastening member is fastened.

Further, the fastening member may be constituted by a stud bolt. In this case, the fastening member has a lower end fixed to the cylinder head, an upper end having a male screw portion for fastening, and having a nut seat surface portion having an enlarged cross-sectional area near the upper end, and below the nut seat surface portion. A nut member as a coupling member is provided in the fastening male screw portion in a state where the fastening male screw portion of the fastening member projects upward from the fastening member insertion hole of the erection member. Screw
The nut member only needs to be set so as to be in contact with the nut seating surface of the fastening member by being further tightened by a predetermined amount after coming into contact with the upper surface of the bridge member.

With this arrangement, the nut member is fastened to the upper end of the fastening member formed of the stud bolt, and the small cross section is appropriately elastically deformed with the fastening, and a force corresponding thereto is applied to the fuel injection nozzle. Works.

It is preferable that a packing having a lower elastic modulus than that of the cylinder head is provided at a nozzle seating portion where the vicinity of the tip of the fuel injection nozzle is seated on the cylinder head.
In this case, the stability is improved when the fuel injection nozzle is fixed by the pressing force.

According to the present invention, two intake valves and two exhaust valves are provided for each cylinder, and an intake port opened and closed by each intake valve and an exhaust port opened and closed by each exhaust valve are provided in a cylinder head. And one camshaft is disposed on one side of the cylinder head, and the intake valves and the exhaust valves are driven by the camshafts through rocker arms. A glow plug mounting portion is disposed on the side opposite to the camshaft side with respect to each cylinder bore, and the glow plug mounting portion is located at a position adjacent to a head bolt hole boss for fixing a cylinder head to a cylinder block. And a plug mounting hole which reaches the cylinder bore through the space between the intake port and the exhaust port. It is effective to be applied to the structure being formed so as to connect the walls and exhaust port walls.

That is, according to such a structure, the intake / exhaust port, the valve operating system, the glow plug for facilitating the start during extremely cold operation, and the like are effectively arranged, and the intake / exhaust port arrangement portion is provided. Although the rigidity of the fuel injection nozzle is increased, the space margin around the cylinder bore is small, and it is difficult to arrange a member for fixing the fuel injection nozzle around the cylinder bore. The installation member and the fastening member are easily arranged, and the fuel injection nozzle is effectively fixed.

In addition to such a structure, a cross drill hole for guiding cooling water to the water jacket is formed at a portion between the intake port and the exhaust port on the side opposite to the glow plug mounting portion with respect to the cylinder bore. In this case, the erection member and the fastening member are arranged without interfering with this, and the fuel injection nozzle is effectively fixed.

If the cam bearing for supporting the camshaft is provided on the cylinder head at an axial position corresponding to the center of the cylinder bore, the cam bearing does not interfere with the above-mentioned fastening members.

The connection and layout of the fuel supply pipe and the fuel return pipe with respect to the fuel injection nozzle are such that the fuel supply pipe is connected to a position below the shoulder portion which is locked by the erection member, and A fuel return pipe may be connected to the upper position, and the fuel return pipe may be arranged so as to avoid the upper end of the fastening member. Further, the fuel supply pipe may be arranged so as to pass above the glow plug mounting portion between the intake port and the exhaust port.

Further, if a passage for connecting a fuel return pipe connected to the fuel injection nozzle and an external pipe is formed in a side wall portion of the head cover mounted on the cylinder head, the fuel injection nozzle may have The connection between the connected pipe and the external pipe is achieved with a simple structure.

It is preferable that the side wall of the head cover mounted on the cylinder head is provided with a recessed portion for allowing the glow plug to be arranged. This facilitates the insertion and removal of the glow plug from the outside.

In addition, a bolt hole boss for attaching a head cover may be provided between the fuel injection nozzles having no bridging member among the fuel injection nozzles.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a direct injection type multi-cylinder diesel engine according to an embodiment of the present invention with a head cover removed (however, a side wall 4b described later is attached), and FIG. 3 and 4 are a plan view and a sectional view of the cylinder head. The engine shown in these figures is a four-cylinder diesel engine, and each cylinder 1
A cylinder block 2 is provided with a cylinder bore constituting A to 1D, a cylinder head 3 mounted on the cylinder block 2, and a head cover 4 mounted on the cylinder head 3.

The cylinder head 3 includes cylinders 1A to 1A.
An intake port 5 and an exhaust port 6 that open to the 1D cylinder bore are formed, and an intake valve 7 and an exhaust valve 8 that open and close the intake port 5 and the exhaust port 6 are provided. In this embodiment, the intake port 5 for the cylinder bore is provided.
And two intake valves 7 for each cylinder so as to open and close the respective intake port openings 5a and the respective exhaust port openings 6a. And two exhaust valves 8.

The intake valves 7 are located on the rear side (right side in FIG. 1) of the cylinder bore in the longitudinal direction of the engine (cylinder arrangement direction), and a straight line connecting the centers of the intake valves 7 in plan view is a cylinder bore center line ( The cylinders are arranged obliquely so as to have a predetermined inclination angle with respect to a straight line connecting the cylinder bore centers of the cylinders. On the other hand, the exhaust valves 8 are located in front of the cylinder bore in the longitudinal direction of the engine (left side in FIG. 1), and a straight line connecting the centers of the exhaust valves 8 in a plan view has a predetermined inclination angle with respect to the cylinder bore center line. So that
They are arranged diagonally. Thus, the two intake valves 7 and the two exhaust valves 8 are staggered in the longitudinal direction of the engine.

The valve system for driving the intake and exhaust valves 7 and 8 is a so-called SOHC (single overhead cam).
One camshaft 11 is disposed on one side in the engine width direction with respect to the cylinder arrangement portion, and a timing pulley 12 is provided at a front end of the camshaft 11.
And a driving force is transmitted from a crankshaft (not shown) to the camshaft 11 via a timing belt.

Between the camshaft 11 and the intake valve 7 and the exhaust valve 8, rocker arms 14 for intake and exhaust valves supported by a common rocker shaft 13 are provided.
15 and the rocker arms 14, 15 swing through the two intake valves 7.
And pressing members 16 and 17 for transmitting to the exhaust valves 8, and the rocker arm 1 is rotated by rotation of the camshaft 11.
4, 15 and pressing members 16, 17, each intake valve 7
And each exhaust valve 8 is driven.

That is, as shown in FIG. 2, the rocker arm 15 for the exhaust valve has a cam roller 18 at one end thereof.
And the exhaust valve cam 1 provided on the camshaft 11
1b is in contact with the cam roller 18, while the other end is in contact with the pressing member 17, and the pressing member 17 is
Both ends are in contact with the upper ends of the valve stems of both the exhaust valves 8 in a state in which they can be vertically reciprocated while being guided by 9. Then, the rocker arm 1 for the exhaust valve according to the rotation of the camshaft 11.
5 is oscillated, and the pressing member 17 moves up and down accordingly, whereby both exhaust valves 8 are simultaneously opened and closed. Further, the cam roller at one end of the rocker arm 14 for the intake valve has the cam 11a for the intake valve of the cam shaft 11.
, While the other end thereof can reciprocate up and down.
6, both ends of the pressing member 16 contact the upper ends of the valve stems of the intake valves 7, and both intake valves 7 are simultaneously opened and closed by the vertical movement of the pressing member 16 accompanying the rocker arm 14 swinging. It has become.

The camshaft 11 is rotatably supported by a plurality of cam bearings 20 at a plurality of positions.
Is provided on the cylinder head 3 at an axial position corresponding to the center of the cylinder bore. Each cam bearing portion 20 is provided with a cam cap 21 which is attached to the cylinder head 3 by a pair of cap bolts 22 and 23 so as to surround the upper half of the camshaft 11. One of the pair of caps 22 and 23 penetrates a rocker shaft 13 installed on the rocker shaft support portion in the up-down direction, so that the rocker shaft 13 is fastened together with the cam cap 21 to the cylinder head 3. It is fixed.

A fuel injection nozzle 25 is provided for each of the cylinders 1A to 1D, and the fuel injection nozzle 25 is disposed so as to face the cylinder bore from above in the cylinder axis direction. It is fixed by the fastening member 60. As will be described in detail later, the bridge member 50 and the fastening member 60 are configured to simultaneously fix both the fuel injection nozzles 25 of the adjacent cylinders. In the illustrated four-cylinder engine, the fuel injection nozzles 25 and the fastening members 60 are located between the first and second cylinders. , And between the third and fourth cylinders. In addition, a bolt hole boss 26 for attaching a head cover is provided between the second and third cylinders in which the bridging member 50 and the fastening member 60 do not exist among the cylinders.

Further, a glow plug mounting portion 27 is provided on a side of each cylinder bore opposite to the camshaft 11 side. The glow plug mounting portion 27 has a plug mounting hole 28 formed in a plug mounting hole boss 29, and an upper end is opened at a position adjacent to the head bolt hole boss 31 on the side of the cylinder head 3. From the intake port 5 and the exhaust port 6 to reach the cylinder bore. The head bolt hole boss 31 has a head bolt hole 32 through which a head bolt for fixing the cylinder head 3 to the cylinder block 2 is inserted. The head bolt hole boss 31 is also provided at a position corresponding to a position below the rocker shaft 13 and between the cam bearing portions 20.

The positional relationship between the suction / exhaust ports 5 and 6 and the glow plug mounting portion 27 will be specifically described with reference to FIG. 2
The two intake ports 5 are formed so as to wrap around to the rear side of the cylinder from one side of the cylinder (the side opposite to the camshaft 11), and open at each end thereof to the cylinder bore.
Exhaust port 6 is on the other side of the cylinder (side of camshaft)
It is formed so as to wrap around to the front side of the cylinder and branch, and each branch end is opened to the cylinder bore.
For such a port arrangement, a plug mounting hole 28 formed from one side toward the cylinder bore passes between the intake port 5 and the exhaust port 6. A plug mounting hole boss 29 forming a plug mounting hole 28 is formed so as to connect the intake port wall and the exhaust port wall. In this way, the space between the suction and exhaust ports is effectively reinforced by the plug mounting hole boss 29.

A cross drill hole 34 for guiding cooling water to the water jacket 33 is formed in a portion between the intake port 5 and the exhaust port 6 on the side opposite to the glow plug mounting portion 27 with respect to the cylinder bore. . In this way, the cooling water is satisfactorily circulated also near the intake / exhaust ports, and the space between the intake / exhaust ports is reinforced by the bosses forming the cross drill holes 34. An abutment surface 36 with the head cover 4 is formed around the cylinder head 3, and a bolt hole 37 for attaching the head cover is formed in the abutment surface 36.

The structure for fixing the fuel injection nozzle 25 will be specifically described with reference to FIGS. The cylinder head 3 is provided with a nozzle mounting hole 41 above the center of the cylinder bore of each cylinder. The nozzle mounting hole 41 has a predetermined lower end side corresponding to the shape of the lower portion of the fuel injection nozzle 25 as described later. The area has a small diameter and the upper part has a large diameter, and a step 42 for seating the nozzle is formed therebetween. A boss portion 43 having a screw hole (female screw portion for fastening) 44 for attaching the fastening member 60 is provided above an intermediate portion between adjacent cylinders. The boss 43 projects upward from the middle deck 3 a of the cylinder head 3. The upper end of the boss 43 is a seat surface 45 on which the lower portion of the fastening member is seated. The seat surface 45 is formed on the same plane as the head cover abutment surface 36 provided on the periphery of the cylinder head 3. ing.

The fuel injection nozzle 25 has a body 25a occupying a large part thereof formed in a substantially cylindrical shape, and a flat portion 25b having flat sides on both sides near the upper end. A step-like shoulder 25c is formed between the body 25a and the body 25a. A connection portion 25e of a fuel supply pipe 46 (see FIG. 1) is provided at an upper portion (a position lower than the shoulder portion 25c) of the body portion 25a, and a fuel return is provided at an upper end portion of the fuel injection nozzle (a position higher than the shoulder portion 25c). Connection part 25f of the piping 47 for use is provided.

At the lower end of the fuel injection nozzle 25, a small diameter portion 25d having a smaller diameter than the body portion 25a is provided, and an injection port is formed at the tip thereof. Then, the lower portion of the fuel injection nozzle 25 is inserted into the nozzle mounting hole 41, and the lower end of the body 25 a is seated on the step 42 in the nozzle mounting hole 41 via the packing 48. The packing 48 is made of a material having a lower elastic modulus than the cylinder head 3, for example, copper. The cylinder head 3 is made of cast iron or aluminum alloy.

The bridging member 50 is formed of a high-strength material such as steel, and is formed in a plate shape having a predetermined length so as to be bridged between the fuel injection nozzles 25 of the adjacent cylinders. 25 has a locking portion 51 for locking the shoulder 25c. The locking portion 51 is formed with a notch 52 that fits into the flat portion 25b on the shoulder 25c of the fuel injection nozzle 25. A circular fastening member insertion hole 53 is formed at the center of the bridge member 25.

The fastening member 60 is formed of a high-strength material such as steel in the form of a threaded rod. In this embodiment, a male screw for fastening corresponding to the screw hole 44 of the cylinder head 3 is provided at the lower end. A bolt having a portion 61 and a hexagonal head 62 at the upper end is formed. Above the fastening male screw portion 61 in the lower portion of the fastening member 60, a seating portion 63 facing the seating surface 45 of the cylinder head 3 is provided. The seating portion 63 is a fastening male screw portion 44.
The cross-sectional area is larger than that, that is, the diameter is larger.
A large-diameter flange 6 is provided below the head 53 at the upper portion of the fastening member 60 as a contact portion with the upper surface of the bridging member 50.
4 are provided.

The fastening member insertion hole 53 of the bridging member 50 is formed to have a slightly larger diameter than the seating portion 63 so that the seating portion 63 of the fastening member 60 can pass therethrough during assembly. The lower part 6 of the flange 64
5 is the fastening member insertion hole 53 in the illustrated assembled state.
The diameter of the seat 63 is slightly smaller than that of the seat 63 so as not to rattle.

A small cross section 66 is provided at an intermediate portion of the fastening member 60. The small cross-section 66 has a smaller cross-sectional area than the seating portion 63 and the upper portion 65, and is preferably formed in a cylindrical shape having a diameter equal to or less than the diameter of the male screw portion 61 for fastening.

In order to provide the restoring force by elastically extending the small cross-section 66 in the assembled state, the following dimensions are set. The following nozzle seating position is a stepped portion 42 in the nozzle mounting hole 41 of the cylinder head 3.
Is the position where the lower end of the body of the fuel injection nozzle 25 is seated.
5c is a position where the locking portion 51 of the erection member 50 comes into contact with 5c.

The vertical distance (L1) from the nozzle seating position to the nozzle locking position by the bridge member 50, the vertical distance (L2) from the nozzle seating position to the seat surface 45 at the upper end of the boss 43, and the fastening member The position of the seat 63 in a state where the bridging member 60 and the bridging member 50 are not elastically deformed (the flange 64 of the fastening member 60 is in contact with the upper surface of the bridging member 50 but no fastening force is applied) (FIG. 5). The relationship between the distance (L3) from the middle two-dot chain line) to the nozzle locking position is set to be [L1> L2 + L3]. That is, in the state where the fastening force is not applied, the predetermined gap C (= L1-L2-L) is formed between the seating portion 63 of the fastening member 60 and the seating surface 45 at the upper end of the boss portion of the cylinder head 3.
3) is set to occur.

The fuel return pipe 47 connected to the upper end of the fuel injection nozzle 25 is
It is arranged so as to avoid the head 62 at the upper end of the fastening member 60 (see FIG. 6). Further, a fuel supply pipe 46 connected to the body 25 a of the fuel injection nozzle 25 is disposed so as to pass above the glow plug mounting portion 27. The fuel supply pipe 46 and the fuel return pipe 47
As shown in FIGS. 1, 7, and 8, an external pipe 7 is connected via a connection portion provided on a side wall portion 4 b forming a part of a head cover 4 mounted on the cylinder head 3.
3,77.

That is, the head cover 4 is divided in advance into a head cover main body 4a and a side wall portion 4b constituting one side wall, and the head cover main body 4a and the side wall portion 4b are mounted on the cylinder head 3 by bolts, respectively.
The head cover body 4a and the side wall 4b are connected to each other by bolts. A joint fitting insertion hole 71 is formed in the side wall portion 4b at a position corresponding to each fuel injection nozzle 25, and the fuel supply pipe 46 is connected to the fuel supply pipe 46 by the joint 72 fitted into the joint fitting insertion hole 71. It is connected to the external pipe 73.

A fuel return connector 74 is attached to the upper end of the center of the side wall 4b in the longitudinal direction. A vertical passage 75 communicating with the connector 74 and a lateral passage 76 communicating with the passage 75 are provided. The passage 76 is formed in the side wall 4b, and opens to the outer surface of the side wall 4b. The return pipe 47 connected to each injection nozzle 25 is connected to the connector 74, while the fuel return external pipe 77 is connected to the passage 76.

At the lower portion of the outer side surface of the side wall portion 4b, there is provided a recessed portion 78 for allowing the glow plug to be disposed, and the glow plug can be inserted and removed outside the side wall portion 4b. .

According to such a structure, the members for fixing the fuel injection nozzle 25 and the intake / exhaust ports 5, 6 disposed around the cylinder bore and various members are prevented from interfering with each other. The nozzle 25 is securely fixed.

That is, in this embodiment, each of the cylinders is provided with two intake valves 7 and two exhaust valves 8, and these valves 7, 8 and the camshaft 11 located on one side of the cylinder arrangement portion are provided. The rocker arms 14, 15 and the like are disposed between them, and the camshaft 11
Since the glow plug mounting portion 27 is disposed on the side opposite to the above, and the cross drill hole 34 and the like are also disposed around the cylinder bore, there is little space margin around the cylinder bore. In particular, the glow plug mounting portion 27 is formed so as to pass between the intake port 5 and the exhaust port 6, and the plug mounting hole boss 29 connects the intake port wall and the exhaust port wall. Since the drill hole 34 is provided between the intake port 5 and the exhaust port 6 on the side opposite to the glow plug mounting portion 27 with respect to the cylinder bore, a member for fixing the fuel injection nozzle 25 is sucked and sucked.
It cannot be placed between exhaust ports.

On the other hand, in this embodiment, the bridging member 50 is suspended between the fuel injection nozzles 25 of the adjacent cylinders at positions above the intake / exhaust ports 5 and 6, the rocker arms 14 and 15, and the like. At the same time, since the fastening member 60 inserted into the bridge member 50 at a position intermediate between the two cylinders is fastened to the cylinder head 3, the intake / exhaust ports 5, 6 and the rocker arms 14, 15 are provided. In addition, the bridging member 50 and the fastening member 60 can be disposed at a position that does not interfere with the glow plug mounting portion 27 and the like. Moreover, since the fuel injection nozzles 25 of the cylinders on both sides are simultaneously fixed by one set of members, the structure is relatively simple.

At the time of assembly, with the lower portion of the fuel injection nozzle 25 inserted into the nozzle mounting hole 41 of the cylinder head 3, the locking portions 51 at both ends of the bridging member 50 are connected to the two fuel injection nozzles 25 of the adjacent cylinder. And the fastening member 60 is inserted into the fastening member insertion hole 53 at the center of the bridging member 50, and the fastening male screw portion 61 at the lower end of the fastening member 60 is engaged with the cylinder head 3. It is screwed into the screw hole 44 of the boss 43. Then, the fastening member 60 made of a bolt is rotated by a tool and fastened to the boss 43.

With this fastening, elastic deformation of the fastening member 60 in the extension direction and elastic deformation of the erection member 50 in the bending direction occur, and the corresponding restoring force acts as a pressing force on the fuel injection nozzles on both sides. The fuel injection nozzle is fixed to the cylinder head.

At this time, an upward force acts on the middle deck 3a of the cylinder head 3 provided with the boss portion 43 with the fastening of the fastening member 60, and when this force is excessive, the middle deck 3a is applied to the middle deck 3a. Since cracks occur to reduce the durability of the cylinder head 3, the fuel injection nozzle 2
5 and a fastening member 6 so that an excessive force does not act on the middle deck 3a of the cylinder head 3 while securing the pressing force required for securely fixing the fixing member 6.
From 0, it is required to appropriately adjust the force acting on the fuel injection nozzle 25 and the middle deck 3a. In response to this requirement, in the structure of the present embodiment, the fastening member 60
6 and the provision of the seating portion 63 with respect to the seating surface 45 of the boss portion 43, it is possible to easily adjust the force acting on the fuel injection nozzle 25 and the middle deck 3a.

That is, since the erection member 50 needs to have a considerably high rigidity to withstand the reaction force from both fuel injection nozzles 25, the pressing force is appropriately adjusted only by the restoring force due to the bending of the erection member 50. Although it is difficult to perform the above, since only a pulling force acts on the fastening member 60, there is no problem in strength even if the small cross-section 66 is provided, and the small cross-section 66 elastically deforms in the elongation direction according to the pulling force. Then, by this and the elastic deformation of the bridge member 50 in the bending direction, it is possible to apply an appropriate pressing force to both the fuel injection nozzles 25.

When the fastening member 60 is tightened to some extent, the seat 63 comes into contact with the seating surface 45 of the boss 43, and even if a tightening force is applied further, the area around the screw hole 44 of the boss 43 is compressed. However, the force applied to the middle deck 3a does not increase, so that an excessive force is prevented from being applied to the middle deck 3a, and the occurrence of cracks is prevented.

At the design stage, the gap C between the seating portion 63 and the seating surface 45 before the fastening force is applied is managed, that is, the dimensions of L1, L2 and L3 related to the gap C are determined. By managing, the axial force (restoring force according to the extension) of the fastening member 60 can be appropriately adjusted. In this case, as shown in FIG. 10, the axial force is proportional to the size of the gap C before the fastening force is applied, and when the rigidity of the fastening member 60 is low (straight line A), when the rigidity is high (straight line). Since the change in the axial force corresponding to the change in the gap C is more gradual than in B), the allowable range of the gap C for adjusting the axial force to a certain appropriate range is wider when the rigidity is reduced. Become
Even if there are manufacturing errors in the dimensions of L1, L2, and L3, it is possible to easily manage the gap C to be within an allowable range, and the axial force can be appropriately adjusted.

When the boss portion for fastening the fastening member 60 is protruded upward from the middle deck 3a, the cooling water circulation space in the water jacket 33 formed below the middle deck 3a is reduced. There is no restriction, and a force associated with the fastening of the fastening member 60 is absorbed to some extent by the boss 43, and an effect of reducing the force applied to the middle deck 3a is obtained.

Furthermore, since the seating surface 45 at the upper end of the boss 43 is formed on the same plane as the head cover abutment surface 36, the upper surface of the boss is simultaneously processed when the head cover abutment surface 36 is finished. In addition, the dimensional accuracy of the position of the seat surface 45 is increased while avoiding an increase in the number of steps.

Since the packing 48 is interposed between the step portion 42 in the nozzle mounting hole 41 and the lower end of the body 25a of the fuel injection nozzle 25, the fuel injection nozzle 25 is stably fixed.

The specific structures of the bridging member 25 and the fastening member 60 for fixing the fuel injection nozzle 25 are not limited to the above embodiment, but can be variously changed.

For example, as shown in FIG. 11, when the cylinder head 3 is made of an aluminum alloy for weight reduction or the like, the seat 63 of the fastening member 60 composed of bolts and the upper end of the boss of the cylinder head 3 are formed. It is also effective to interpose a washer 68 between the seat surface 45 and the seat surface 45. The erection member 50, the fastening member 60, and the washer 68
Is made of steel.

This is effective for suppressing the deformation of the boss portion 43 at the time of tightening while reducing the size. That is, since the aluminum alloy cylinder head 3 has a lower rigidity than the cast iron cylinder head 3, if the boss 43 and the fastening member 60 have relatively small diameters for compactness and weight reduction, the seating of the fastening member 60 When the fastening member 60 is further tightened after the portion 63 abuts on the seat surface 45, there is a concern that the boss portion 43 is deformed so that the seat portion 63 is embedded in the boss portion 43. Such a situation can be prevented by interposing.

In the above embodiment, the fastening member 60 is made of a bolt, but as shown in FIG.
1 is fixed to the boss portion 43 of the cylinder head 3 in advance, and a fastening member 80 is formed by a stud bolt having a male screw portion 82 for fastening at an upper end portion.
Alternatively, a nut member 85 as a connecting member on the erection member side may be screwed.

In this case, a nut seat surface portion 83 having an enlarged cross-sectional area is formed near the upper end of the fastening member 80 composed of stud bolts (under the male screw portion 82), and below the nut seat surface portion 83. A small cross section 66 is formed. The male screw portion 82 for fastening of the fastening member 80 is
The nut member 85 is screwed into the fastening male screw portion 82 in a state where the nut member 85 protrudes upward from the fastening member insertion hole 53, and the nut member 85 comes into contact with the upper surface of the bridging member 50, and is further tightened by a predetermined amount. As a result, it comes into contact with the nut seating surface 83 of the fastening member 80.

Also according to this structure, the distance from when the nut member 85 contacts the upper surface of the bridge member 50 to when the nut member 85 contacts the nut seating surface 83 is equivalent to the dimension C in FIG. The same operation as the above embodiment can be obtained.

The case where the fastening member 80 is a stud bolt as in this embodiment and the case where the fastening member 6 is
Comparing with the case where 0 is a bolt, the stud bolt requires preliminary work to be embedded in the boss 43, and
Since the nut member 85 is required, a bolt is advantageous for reducing the number of parts and man-hours. On the other hand, in the case of the stud bolt, there is no problem such as deformation due to compression of the boss during tightening as in the case of the bolt, and it is not necessary to increase the diameter of the boss to secure strength. This is advantageous for downsizing.

[0069]

As described above, according to the present invention, in a direct injection type multi-cylinder diesel engine, a bridging member is bridged between both fuel injection nozzles of adjacent cylinders, and both fuels are locked at both ends of the bridging member. With the shoulder of the injection nozzle locked, a fastening member is inserted into a fastening member insertion hole formed in the center of the bridge member, and upper and lower ends thereof are connected to the bridge member and the cylinder head. As a result, the fuel injection nozzle is fixed with a relatively simple structure while avoiding interference between various members such as intake / exhaust ports and valve trains arranged around the cylinder bore and the above-mentioned erection members and fastening members. can do.

In addition, a corresponding fastening screw portion and a seating portion are provided at the connecting portion between the lower end portion of the fastening member and the cylinder head or the connecting portion between the upper end portion of the fastening member and the connecting member on the bridge member side. A facing portion is provided, and a small cross-sectional portion having a smaller cross-sectional area than the both end portions is formed at an intermediate portion of the fastening member, and the corresponding fastening screw portion is screwed into the facing portion for seating. Are tightened to a state where they come into contact with each other, so that the small cross-section portion of the fastening member elastically extends and a predetermined restoring force is generated. Since the fuel injection plug is configured to act, the fuel injection plug can be fixed satisfactorily, and an excessive force can be prevented from being applied to the cylinder head at the time of fastening.

[Brief description of the drawings]

FIG. 1 is a plan view of a direct-injection diesel engine according to the present invention with a head cover removed.

FIG. 2 is a sectional view of the main part.

FIG. 3 is a plan view of a cylinder head.

FIG. 4 is a horizontal sectional view of a cylinder head.

FIG. 5 is an enlarged sectional view of a fixed portion of a fuel injection nozzle.

FIG. 6 is an enlarged plan view of the same part.

FIG. 7 is a side view of a side wall portion of the head cover.

FIG. 8 is a cross-sectional view of a fuel return pipe connection portion on a side wall portion of the head cover.

FIG. 9 is a view of the side wall of the head cover as viewed from the front end side.

FIG. 10 is a diagram illustrating a relationship between a gap between a seating portion and a seating surface and an axial force of the fastening member before a fastening force is applied to the fastening member.

FIG. 11 is an enlarged sectional view showing another embodiment of the fuel injection nozzle fixing portion.

FIG. 12 is an enlarged sectional view showing still another embodiment of a fuel injection nozzle fixing portion.

[Explanation of symbols]

 1A to 1D Cylinder 3 Cylinder head 4 Head cover 4b Side wall 5 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 11 Camshaft 14, 15 Rocker arm 20 Cam bearing 25 Fuel injection nozzle 25c Shoulder 27 Glow plug attachment 33 Water Jacket 34 Cross drill hole 41 Nozzle mounting hole 43 Boss part 44 Screw hole 45 Seat surface 46 Fuel supply pipe 47 Fuel return pipe 48 Packing 50 Bridge member 51 Locking part 53 Fastening member insertion hole 60 Fastening member 61 Fastening male screw part 62 head 63 seating part 64 contact part 66 small section part 68 washer 74 connector 75, 76 passage 80 fastening member 82 fastening male screw part 85 nut member

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02F 1/24 F02F 1/24 FR (72) Inventor Hiroaki Yasuda 3-1, Fuchu-cho, Fuchu-cho, Aki-gun, Hiroshima Mazda

Claims (16)

[Claims] In a direct injection type multi-cylinder diesel engine in which a fuel injection nozzle is provided for each cylinder so as to face the cylinder bore from above in the cylinder axis direction, shoulder portions of both fuel injection nozzles of adjacent cylinders are formed. It has a locking member at each end and a locking member insertion hole at the center, and has a mounting member bridged over the two fuel injection nozzles, and a locking member insertion hole of the mounting member. A rod-shaped fastening member having upper and lower ends joined to the bridging member and the cylinder head, and a joining portion between a lower end of the fastening member and the cylinder head or an upper end of the fastening member and a bridging member-side joining member A corresponding fastening screw portion and a facing portion for seating are provided at a coupling portion with the small member, and a small cross-sectional portion having a smaller cross-sectional area than both end portions is formed at an intermediate portion of the fastening member. The corresponding fastening screw portions are screwed together and fastened to a state in which the facing portion for seating abuts, whereby the small cross-section portion of the fastening member is elastically extended and a predetermined restoring force is obtained. Wherein the restoring force acts as a pressing force on the fuel injection nozzles via the erection member. 2. The direct-injection multi-cylinder diesel engine according to claim 1, wherein the diameter of the small cross section of the fastening member is equal to or less than the diameter of the screw portion for fastening. 3. A boss portion having a female screw portion for fastening is formed at a fastening member connecting portion of the cylinder head, and the fastening member has a male screw portion for fastening at a lower end and a female thread portion for fastening from the male screw portion for fastening. A seat having an enlarged area facing the seating surface at the upper end of the boss portion, and having an abutment portion at the upper end portion with the upper surface of the erection member, and the abutting portion and the seating portion Consisting of a bolt having a small cross-section between
The vertical distance (L1) from the nozzle seating position where the vicinity of the tip of the fuel injection nozzle is seated on the cylinder head to the nozzle locking position where the locking portion of the bridge member abuts the shoulder of the fuel injection nozzle; Between the vertical distance (L2) from the upper surface of the boss to the seat surface at the upper end of the boss and the vertical distance (L3) from the seat to the locking position when the fastening member is not elastically deformed. Is [L1> L
2 + L3], wherein the direct injection type multi-cylinder diesel engine according to claim 1 or 2, is provided. 4. A boss portion having a female screw portion for fastening protrudes upward from a deck of a cylinder head, and a water jacket is formed below the deck in the cylinder head. Direct injection multi-cylinder diesel engine. 5. A head cover abutment surface is provided at a peripheral portion of the cylinder head, and the head cover abutment surface and an upper surface of a boss having a female screw portion for fastening are formed on the same surface. The direct injection type multi-cylinder diesel engine according to claim 3 or 4. 6. The cylinder head is made of an aluminum alloy, the bridging member and the fastening member are made of steel, and a washer is interposed between a seating surface at an upper end of a boss portion of the cylinder head and a seating portion of the fastening member. The direct injection type multi-cylinder diesel engine according to any one of claims 3 to 4, characterized in that: 7. The fastening member has a lower end fixed to the cylinder head, an upper end having a male screw portion for fastening, a nut seat surface portion having an enlarged sectional area near the upper end, and a nut seat surface portion. It is made of a stud bolt having a small cross section below, and in a state in which a male screw portion for fastening of this fastening member projects above the fastening member insertion hole of the erection member,
A nut member as a coupling member is screwed into the male screw portion for fastening, and the nut member contacts the upper surface of the erection member and is further tightened by a predetermined amount, so that the nut member comes into contact with the nut seat surface of the fastening member. The direct-injection multi-cylinder diesel engine according to claim 1, wherein the direct-injection multi-cylinder diesel engine is set to be in contact with each other. 8. The packing according to claim 1, wherein a packing having a lower elastic modulus than that of the cylinder head is interposed at a nozzle seating portion where the vicinity of the tip of the fuel injection nozzle is seated on the cylinder head. Direct injection multi-cylinder diesel engine. 9. A cylinder head is provided with two intake valves and two exhaust valves for each cylinder, and an intake port opened and closed by each intake valve and an exhaust port opened and closed by each exhaust valve are formed in a cylinder head. One camshaft is arranged on one side of the cylinder head, and each intake valve and each exhaust valve are configured to be driven by the camshaft through a rocker arm. A glow plug mounting portion is provided on the side opposite to the camshaft side, and the glow plug mounting portion is provided with the intake port and the exhaust port from a position adjacent to a head bolt hole boss for fixing a cylinder head to a cylinder block. A plug mounting hole that passes through the gap to reach the cylinder bore,
The direct-injection multi-cylinder diesel engine according to any one of claims 1 to 8, wherein a plug mounting hole boss forming the plug mounting hole is formed so as to connect the intake port wall and the exhaust port wall. engine. 10. A cross drill hole for guiding cooling water to a water jacket is formed in a portion between an intake port and an exhaust port on a side opposite to a glow plug mounting portion with respect to a cylinder bore. A direct injection multi-cylinder diesel engine according to claim 9. 11. The direct-injection multi-cylinder diesel engine according to claim 9, wherein a cam bearing portion for supporting the camshaft is provided on the cylinder head at an axial position corresponding to a center portion of the cylinder bore. . 12. A fuel supply pipe is connected to a position below a shoulder portion of the fuel injection nozzle which is locked by the bridge member, and a fuel return pipe is connected to a position above the shoulder portion. The direct-injection multi-cylinder diesel engine according to any one of claims 9 to 11, wherein the return pipe is arranged so as to avoid the upper end of the fastening member. 13. The direct injection multi-cylinder diesel engine according to claim 12, wherein the fuel supply pipe is disposed so as to pass above the glow plug mounting portion between the intake port and the exhaust port. 14. A passage for connecting a fuel return pipe connected to a fuel injection nozzle and an external pipe is formed in a side wall of a head cover mounted on a cylinder head. Item 12 or 1
3. A direct injection multi-cylinder diesel engine according to 3. 15. A head cover mounted on a cylinder head is provided with a recessed portion on a side wall portion for allowing a glow plug to be disposed.
The described direct injection multi-cylinder diesel engine. 16. A head cover mounting bolt hole boss is provided between the fuel injection nozzles between the fuel injection nozzles where no bridge member is present. The described direct injection multi-cylinder diesel engine.