JP3224082B2 - Diesel engine fuel supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a diesel engine.

[0002]

2. Description of the Related Art In a multi-cylinder diesel engine, a common rail is provided for a plurality of cylinders, and high-pressure fuel pressurized by a supply pump is stored in a pressure accumulating chamber in the common rail. 2. Description of the Related Art A fuel supply device in which high-pressure fuel stored in a pressure accumulation chamber of a common rail is injected into a combustion chamber by an electromagnetically operated injector provided in each cylinder is conventionally known.

An example of a fuel supply device for a diesel engine having the above-mentioned common rail will be described with reference to FIGS. In the figure, reference numeral 10 generally indicates a direct injection type diesel engine for vehicles such as trucks. The engine 10 includes a crankcase 14 having a plurality of cylinders or cylinders 12, and a top portion is provided in each cylinder or cylinder 12. Piston 18 with combustion chamber cavity 16 in it
Are slidably fitted. The above crankcase 14
Above the cylinder head 2 via a head gasket.
In the cylinder head 20, there are provided an intake port 22 and an exhaust port 24, and an intake valve 26 and an exhaust valve 28 for controlling communication between the intake port and the exhaust port and the cylinder or the cylinder 12, respectively. And an injector 30 for injecting fuel into the combustion chamber cavity 16 when the piston 18 is near the compression top dead center. Above the cylinder head 20, a cam frame 32 having a substantially planar overall frame shape is mounted.
2, an intake cam 34 for controlling the opening and closing of the intake valve 26 is provided.
, An exhaust camshaft 40 having an exhaust cam 38 for opening and closing the exhaust valve 28, and a rocker arm 42 for transmitting the lift of the intake cam 36 to the intake valve 26.
And a rocker arm 44 for transmitting the lift of the exhaust cam 38 to the exhaust valve 28, and the upper half of the injector 30 are housed therein.

An intake manifold 46 is mounted on one side wall of the cylinder head 20, and the intake manifold 4
The branch for each cylinder 6 is connected to the inlet end of the intake port 22. An exhaust manifold 48 is mounted on the other side wall of the cylinder head 20, and a branch for each cylinder of the exhaust manifold 48 is connected to an outlet end of the exhaust port 24. A common rail 52 is attached to a side surface of the crankcase 14 via a bracket (not shown) or the like.
A pressure storage chamber 54 for storing high-pressure fuel is provided.

[0005] The common rail 52 extends in a direction perpendicular to the plane of the paper of FIG. 5, and the side surface thereof is provided with the same number of fuel delivery sections 56 as the number of cylinders, and each fuel delivery section 56 communicates with the accumulator chamber 54. are doing. Further, the fuel delivery section 56 has a 2
The fuel injection pipes 58a and 58b are connected to the fuel inlet 60 of the injector 30 of the corresponding cylinder via the fuel injection pipes 58a and 58b. Further, the fuel injection tubes 58a and 58b are connected to each other via an intermediate connecting portion 62 mounted on the side wall 32a of the cam frame 32 on the side of the common rail 52. In FIG. 5, reference numeral 64 denotes the injector 30.
The fuel discharge section 64 returns excess fuel to the fuel tank.

FIG. 6 is a schematic configuration diagram of a fuel injection system including the injector 30 and the common rail 52. The high pressure fuel pressurized by the supply pump 66 is supplied to the pressure accumulating chamber 54 of the common rail 52. The supply pump 66 is operated by a feed pump 68 which is driven in conjunction with a crankshaft of the engine 10 to control a discharge amount control valve 7.
A plunger 74 is provided to pressurize the low-pressure fuel supplied to the plunger chamber 72 through the cylinder 0. The plunger 74 is reciprocated by a cam 78 on a pump shaft 76 driven in conjunction with a crankshaft of the engine.

The discharge amount control valve 70 is provided with load information Ac of the engine 10, for example, an output signal of an accelerator opening detecting device 80 for detecting the accelerator opening of the vehicle, and a rotational speed detecting device 82 for detecting the rotational speed of the engine. Rotation speed information Ne,
In addition, it receives, as a main control signal, output information of a common rail pressure sensor 84 that detects the pressure Pc of the high-pressure fuel in the pressure accumulating chamber 54 of the common rail 52, and further, if necessary, furthermore, the cooling water temperature Tw of the engine 10 and the fuel tank 86. The opening and closing of the discharge amount control valve 70 is controlled by a control unit 88 that provides a drive output in consideration of an auxiliary signal or information such as the fuel temperature Tf of the plunger chamber 7.
2, the amount of pressurized fuel supplied to the common rail 52 from the supply passage 90 through the one-way valve is controlled, so that the pressure of the high-pressure fuel in the accumulator 54 is controlled.

Next, the injector 30 is provided with a valve body 94 having an injection hole 92 facing the combustion chamber of each cylinder of the engine 10, and the injector 30 is slidably fitted in the valve body 94. The valve includes a needle valve 96 that opens and closes, and a fuel reservoir 98 formed in the valve body 94 surrounding a step portion 96 ′ of the needle valve 96. Also, the valve body 94
A pressure pin 102 and a control piston 104 are disposed coaxially with the needle valve 96 in a nozzle holder 100 integrally fixed by a retaining nut (not shown). It is slidably fitted in the control oil chamber 106. The pressure pin 102 is acted upon by a pressure spring 108 which constantly urges the needle valve 96 in the closing direction. In the nozzle holder 100 and the valve body 94, there is provided a main fuel passage 110 for constantly communicating the pressure accumulating chamber 54 of the common rail 52 with the fuel reservoir 98. In the nozzle holder 100, a main fuel passage 110 is provided. A branch fuel passage 116 is provided which branches and communicates with the control oil chamber 106 via a three-way solenoid valve 112 and an orifice 114.

The three-way solenoid valve 112 is controlled to be opened and closed by the control unit 88 so that the injector 3
The fuel injection amount, injection rate and injection timing of 0 are controlled. That is, the three-way solenoid valve 11 is controlled by the control unit 88.
2 is deenergized, the high-pressure fuel in the common rail 52 is supplied from the branch fuel passage 116 to the control oil chamber 106 through the orifice 114, so that the needle valve 96 closes the control piston 104 and the pressure spring 108. Since the valve force acts and the needle valve 96 is held at the valve closing position, fuel is not injected from the injection hole 92. Next, when the three-way solenoid valve 112 is energized by the control unit 88, the communication between the control oil chamber 106 and the branch fuel passage 116 is cut off, and the control oil chamber 106 is connected to the leak-off passage 118 for control. Since the fuel pressure applied to the piston 104 is eliminated, the needle valve 96 is lifted by the fuel pressure in the fuel reservoir 98 and fuel is injected from the injection hole 92. In order to set the fuel injection timing of the injector 30 for each cylinder, the control unit 88 receives the crank angle information θc from the crank angle sensor 120.
Are supplied in addition to the load information Ac indicating the operating state of the engine, the rotation speed information Ne, the cooling water temperature information Tn, the fuel temperature information Tf, the common rail pressure information Pc, and the like.

In the conventional fuel supply system for a diesel engine having a common rail, the common rail 52 is attached to the crankcase 14 and connects the fuel delivery section 56 of the common rail to the fuel inlet section 60 of the injector 30. Two fuel injection pipes 58a and 58b are required, and an intermediate connecting portion 62 is provided on the side wall 32a of the cam frame 32 to form the two fuel injection pipes 58a and 58b.
It is necessary to connect b and to prevent the oil from flowing out of the cam frame 32 to the outside. Therefore, as compared with the case where the common rail and the injector are connected by a single fuel injection pipe, only the connection portion between the intermediate connecting portion 62 and the fuel injection pipes 58a and 58b causes more troubles such as high-pressure fuel leakage, and There is a disadvantage in that the pressure loss due to the change in the cross section of the fuel flow path in the intermediate connecting portion 62 is large. In addition, the intermediate connecting portion 62, which is complicated in structure and requires many parts, is provided. Because of the necessity, the number of parts increases and the number of man-hours increases, so that there is a disadvantage that manufacturing costs and maintenance costs increase. Further, during operation of the engine, the cylinder head 20 and the cam frame 32 and the crankcase 14 vibrate separately, so that the common rail 52 attached to the crankcase 14 is connected to the injector 30 mounted on the cylinder head 20 side. Fuel injection pipes 58a and 58b
Among them, the bending load is repeatedly applied to the outer injection pipe 58a, and the injection pipe 58a is relatively easily damaged.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks and disadvantages of a fuel supply system for a diesel engine having a common rail, and has a simple structure and a small number of parts. It is an object of the present invention to provide a fuel supply device which is low in cost and maintenance cost and has a low possibility of occurrence of troubles such as leakage of high-pressure fuel.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an intake / exhaust valve actuating device and a fuel injector for each cylinder which are mounted on a cylinder head of an engine and cooperate with the cylinder head. A cam frame to house,
A pressure accumulating chamber mounted on a side wall of the cam frame for storing high-pressure fuel supplied to the injector, and a fuel delivery portion for each cylinder that communicates with the accumulating chamber and that is inserted into an opening of the cam frame side wall. And a fuel injection pipe for each cylinder, which is connected to the fuel delivery section of the common rail at one end and connected to the fuel inlet of the injector at one end, and is a single pipe member.
And the side wall of the cam frame and the side wall.
Between the common rail mounting surface
Seal that prohibits the opening of the side wall of the system from communicating with the atmosphere
A fuel supply device for a diesel engine (hereinafter referred to as a first invention) characterized by having a stage, a cylinder head accommodating a plurality of cylinders of intake / exhaust valves and valve operating devices, and a fuel injector, and the cylinder head A common pressure chamber mounted on a side wall of the cylinder and storing a high-pressure fuel supplied to the injector; When one end of it comprises a fuel injection pipe of each cylinder comprising the other of which is connected to the fuel inlet portion each single tubular member of the injector while being connected to the fuel delivery part of the common rail, further ,
Common rail opposing the side wall of the Linda head
The opening of the cylinder head side wall is
A fuel supply device for a diesel engine (hereinafter referred to as a second invention), characterized in that a seal means for preventing communication with the air is provided .

According to the first and second aspects of the present invention,
Cam frame or cylinder mounted on cylinder head
Attach a separate common rail to the side wall of the head itself, and
Through the opening in the side of the frame or cylinder head.
Connect the fuel injection pipe consisting of one pipe member to the injector
It has a simple structure that is easy to assemble and maintain.
Also, the cam frame or cylinder head side wall and
The above-mentioned opening communicates with the atmosphere between the mounting surface of the mon rail.
Sealing means is provided to prevent fuel
The connection between the outlet and the pipe member goes to the cam frame or cylinder.
Lubricating oil and high-pressure fuel
Can be prevented from leaking outside .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS. (Note that FIG.
The same reference numerals are used for members and portions that are substantially the same as or correspond to those of the conventional fuel injection device described with reference to FIG. First, referring to FIGS. 1 to 4 showing the first invention, each cylinder or cylinder 12 is placed in a cylinder head 20 mounted above a crankcase 14 via a head gasket.
Intake port 22 and exhaust port 24, and an intake valve 2 for controlling communication between the intake and exhaust ports and the combustion chamber in the cylinder.
6, an exhaust valve 28, and an injector 30 for fuel injection are provided. Further, a frame type cam frame or rocker housing 3 mounted on the cylinder head 20 is provided.
2, a valve gear for opening and closing the intake valve 26 and the exhaust valve 28, that is, an intake cam shaft 36 having an intake cam 34 and a rocker arm 42 for transmitting the lift of the intake cam 34 to the intake valve 26; An exhaust camshaft 40 provided with an exhaust cam 38 and a rocker arm 44 for transmitting the lift of the exhaust cam 38 to the exhaust valve 28 and an upper half of the injector 30 are housed therein.

The above cam frame or rocker housing 3
The common rail 52 is mounted on the side wall 32 a of the second intake manifold 46 by a plurality of mounting bolts 122. A pressure accumulating chamber 54 is provided inside the common rail 52, and a plurality of fuel delivery portions 56 corresponding to each cylinder of the engine 10 are protruded from a common rail mounting surface abutting on the cam frame side wall 38 a. Each fuel delivery section 56 communicates with the pressure accumulation chamber 54 respectively. The common rail 52 is connected to a supply passage 90 for supplying high-pressure fuel discharged from the supply pump 66 shown in FIG. 6 to the accumulator 54, and detects the fuel pressure in the accumulator 54 to detect the fuel pressure. A common rail pressure sensor 84 for outputting to the control unit 88 is provided. Further, although not shown, when the pressure in the pressure accumulating chamber 54 becomes equal to or higher than a preset maximum pressure, an abnormal high pressure is released. A pressure limiter is provided.

The fuel delivery section 56 includes the cam frame 32
The fuel delivery portion 56 for each cylinder and the fuel inlet portion 60 of the injector 30 are connected by a single fuel injection pipe 58. As is well shown in the main part enlarged sectional view of FIG.
A concave groove 126 surrounding the opening 124 is provided on a mounting surface of the common rail 52 which abuts on the cam frame side wall 32a, and an O-ring 128 is inserted into the concave groove 126 to be pressed against the outer surface of the side wall 32a. And a sealing means for preventing oil in the cam frame 32 from flowing out. A rocker cover 132 is attached to the upper opening of the cam frame 32 via a gasket 130 so that the oil in the cam frame 32 is not scattered outside from the upper opening and escapes. ing.

As shown in the enlarged plan view of the main part of FIG. 4, the fuel discharge portion 64 of the injector 30 of each cylinder is connected via a return pipe 118 'forming a leak-off passage 118 of FIG. It communicates with the fuel tank 86. Further, the injector 30 is an electromagnetically actuated injector substantially equivalent to that described with reference to FIG.

According to the first aspect of the present invention, the common rail 52 is directly mounted on the side wall 32a of the cam frame 32, and the fuel delivery section 56 and the injector 3 of the common rail 52 are mounted.
Since the fuel inlet 60 is connected by a single fuel injection pipe 58, the structure is simpler and the number of parts is smaller than that of a conventional fuel supply system in which two fuel injection pipes are connected by an intermediate connection. And there is an advantage that manufacturing cost and maintenance cost are reduced, and since there is no intermediate connection portion, there is no pressure loss due to a change in the flow path cross section at the connection portion, and further, high pressure from the intermediate connection portion There is an advantage that there is no problem of occurrence of fuel leakage. Since the common rail 52 is mounted on the cam frame 32 and vibrates integrally with the cam frame 32 and the cylinder head 20 during operation of the engine, the common rail 52 and the cam frame 32 are separately provided on the fuel injection pipe 58. In this case, the bending load generated when the vibration is generated does not act, and the durability of the fuel injection pipe 58 can be ensured.

Next, in the second invention, a cylinder head common to a plurality of cylinders or cylinders, that is, without the cam frame or the rocker housing 32, in other words, the cylinder head 20 and the cam frame 32 of the first invention are combined. The intake port 22, exhaust port 2
4. In the engine 10 that accommodates the intake valve 26, the exhaust valve 28, the valve apparatus for opening and closing these intake and exhaust valves, and the electromagnetically actuated injector 30, the side wall of the cylinder head on the intake manifold side has the first invention and The common rail 52 is mounted in substantially the same manner.
The fuel delivery portion 56 to the injector 30 of each cylinder protruding from the mounting surface abutting on the cylinder head side wall is inserted into a corresponding opening 124 provided in the cylinder head side wall, and the fuel delivery portion 56 corresponds to each fuel delivery portion 56. It is sufficient to connect the fuel inlet portion 60 of the injector 30 with a single fuel injection pipe 58, and it is apparent that the second invention can provide substantially the same advantages or effects as those of the first invention. It is.

In each of the first and second inventions, the cam frame 32 or the opening 124 of the cylinder head 20 through which the fuel delivery portion 56 of the common rail 52 is inserted.
Constituting a sealing means for preventing oil from flowing out of the cam frame 32 or the cylinder head 20 from the
The ring or gasket may be arranged to surround the perimeter of each opening 124
An annular seal or a plate-like gasket having an oval or rectangular front shape surrounding the outside of the group may be used. Further, the concave groove 126 for accommodating the O-ring 128 can be provided not on the common rail 52 side but on the cam frame side wall 32a side (first invention) or the cylinder head side (second invention).

[0021]

As described above, the cam frame mounted on the cylinder head of the engine and accommodating the intake / exhaust valve operating device and the fuel injector for each cylinder in cooperation with the cylinder head, and the cam frame A common pressure storage chamber mounted on the side wall of the cylinder and storing a high-pressure fuel supplied to the injector; When one end of it comprises a fuel injection pipe of each cylinder comprising the other of which is connected to the fuel inlet portion each single tubular member of the injector while being connected to the fuel delivery part of the common rail, further , The side wall of the above cam frame
And the common rail mounting surface facing the side wall,
The opening of the cam frame side wall must not communicate with the atmosphere.
Characterized in that a sealing means for stopping is provided.
A cylinder head containing a fuel supply device for a diesel engine, a plurality of cylinder intake / exhaust valves and valve trains, and a fuel injector, and a pressure accumulator mounted on a side wall of the cylinder head and storing high-pressure fuel supplied to the injector. A common rail communicating with the chamber and the pressure accumulating chamber, and having a fuel delivery section for each cylinder inserted into the opening of the cylinder head side wall, and one end connected to the fuel delivery section of the common rail and the other end. the result comprises a fuel injection pipe of each cylinder consisting of connected each single tubular member to the fuel inlet of the injector, further, the Shirindahe
And the common rail mounting surface facing the side wall
The opening in the cylinder head side wall communicates with the atmosphere
The fuel supply system of the diesel engine, which is scarcely marked by the provision of a sealing means for inhibiting the use of the same, has a simpler structure and a smaller number of parts compared to the same type of the conventional device, so that the manufacturing cost and the maintenance cost are low. Further, it is possible to provide a fuel supply device having various advantages such as a small pressure loss in the fuel passage from the common rail to the injector and an improvement in durability of the fuel injection pipe, which is industrially useful. .

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an entire diesel engine to which a first invention is applied.

FIG. 2 is a sectional view showing a fuel supply device portion of the engine shown in FIG.

FIG. 3 is an enlarged partial cross-sectional view of a main part of FIG. 2;

FIG. 4 is a partial plan view showing an enlarged main part of FIG. 2;

FIG. 5 is a sectional view similar to FIG. 2, showing a fuel supply device in a conventional diesel engine.

FIG. 6 is a schematic configuration diagram showing a fuel supply device in a diesel engine having a common rail.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Direct injection diesel engine, 12 ... Cylinder or cylinder, 14 ... Crankcase, 16 ... Combustion chamber cavity, 18 ... Piston, 20 ... Cylinder head, 22 ...
Intake port, 24 ... exhaust port, 26 ... intake valve, 28 ...
Exhaust valve, 30 ... Injector, 32 ... Cam frame, 3
4 intake cam, 38 exhaust cam, 42 and 44 rocker arm, 52 common rail, 54 accumulator chamber, 56 fuel delivery section, 58, 58a and 58b fuel injection pipe, 60
... Fuel inlet part, 64 ... Fuel discharge part, 66 ... Supply pump, 68 ... Feed pump, 74 ... Pressurizing plunger, 9
2 ... injection hole, 94 ... valve body, 96 ... needle valve, 104 ...
Control piston, 106: control oil chamber, 112: three-way solenoid valve, 114: orifice, 118 and 118 ': leak passage.

Continuation of front page (56) References JP-A-8-21340 (JP, A) JP-A-6-307310 (JP, A) JP-A-9-264227 (JP, A) JP-A-2-147857 (JP) , U) Japanese Utility Model Hei 4-65959 (JP, U) Japanese Utility Model Hei 7-109963 (JP, U)

Claims (2)

(57) [Claims] 1. A cam frame mounted on a cylinder head of an engine and accommodating an intake / exhaust valve operating device and a fuel injector for each cylinder in cooperation with the cylinder head;
A pressure accumulating chamber mounted on a side wall of the cam frame for storing high-pressure fuel supplied to the injector, and a fuel delivery portion for each cylinder that communicates with the accumulating chamber and that is inserted into an opening of the cam frame side wall. And a fuel injection pipe for each cylinder, which is connected to the fuel delivery section of the common rail at one end and connected to the fuel inlet of the injector at one end, and is a single pipe member.
And the side wall of the cam frame and the side wall.
Between the common rail mounting surface
Seal that prohibits the opening of the side wall of the system from communicating with the atmosphere
A fuel supply device for a diesel engine, comprising a step . 2. A cylinder head containing a plurality of cylinder intake and exhaust valves, a valve train, and a fuel injector,
A pressure accumulating chamber mounted on a side wall of the cylinder head for storing high-pressure fuel supplied to the injector, and a fuel delivery portion for each cylinder that communicates with the accumulating chamber and that is inserted into an opening of the cylinder head side wall. And a fuel injection pipe for each cylinder, which is connected to the fuel delivery section of the common rail at one end and connected to the fuel inlet of the injector at one end, and is a single pipe member. And the same side wall as the cylinder head.
The space above the common rail mounting surface facing the side wall
Prohibit the opening of the side wall of the Linda head from communicating with the atmosphere
The fuel supply device for a diesel engine, wherein a sealing means is provided that.