JP3687149B2 - Direct injection diesel engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct injection diesel engine.
[0002]
[Prior art]
In a direct injection type diesel engine, as shown in Japanese Patent Laid-Open No. 6-33778, a fuel injection valve is provided in a cylinder head along the axial direction of the cylinder at a central portion in the radial direction of the cylinder. A plurality of intake ports that open to the cylinder on the radially outer side of the cylinder, and each intake port has an intake valve that opens and closes the intake port, and the valve shaft of the intake valve is in the axial direction of the cylinder There are some that are provided along the line. Thereby, as is known, in addition to good fuel consumption, it is possible to achieve both reduction of exhaust gas and high performance.
[0003]
On the other hand, as shown in Japanese Patent Laid-Open No. 63-31767, as a fuel injection valve, a fuel inlet portion for introducing fuel into the fuel injection valve is provided on a side portion of the fuel injection valve, and the fuel inlet portion and the injection portion are injected. A pump connected to a pump via a supply pipe is being developed. If this is applied to the direct injection diesel engine, it is possible to obtain a direct injection diesel engine having a so-called side-out fuel inlet.
[0004]
[Problems to be solved by the invention]
However, simply by combining the contents of both publications, the resulting direct-injection diesel engine has a higher overall height, and accordingly, the distance between the fuel inlet and the injection pump becomes longer, and the fuel supply There is a possibility that the length of the pipe becomes long.
[0005]
The present invention has been made in view of the above circumstances, and the object thereof is to keep the overall height low and to shorten the length of the fuel supply pipe connecting the fuel inlet and the injection pump as much as possible. It is to provide a direct injection diesel engine.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention (invention of claim 1)
The cylinder head is provided with a fuel injection valve along the axial direction of the cylinder at a central portion in the radial direction of the cylinder, and a plurality of intake air that opens to the cylinder on the radially outer side of the cylinder from the fuel injection valve A port is formed, and a fuel inlet portion for guiding fuel into the fuel injection valve is provided at a side portion of the fuel injection valve, and the fuel inlet portion and the injection pump are connected via a supply pipe. In the direct injection diesel engine in which an intake valve that opens and closes the intake port is provided in the intake port so that the valve shaft of the intake valve is along the axial direction of the cylinder,
A plurality of the cylinders are arranged in a row,
Among the plurality of cylinders, at least a plurality of intake valves for each cylinder at both ends in the cylinder arrangement direction are arranged so as to approach each other toward the outlet side of the injection pump in the width direction of the cylinder head,
The fuel inlet for each cylinder extends to the injection pump side along the direction in which the intake valve for each cylinder is disposed,
The intake port is a tangential port,
The fuel inlet portion is disposed in the vicinity of the tangential port, and the injection pump is positioned at a position lower than the upstream end opening of the intake port in the cylinder head.
[0008]
【The invention's effect】
According to the first aspect of the present invention, the fuel inlet portion is disposed in the space corresponding to the lowered height by utilizing the property as a tangential port whose height is lower than that of the helical port or the like. As a result, the height of the fuel inlet can be reduced to reduce the overall height, and the distance between the fuel inlet and the injection pump can be shortened to connect the fuel inlet and the injection pump. The length of the fuel supply pipe can be made as short as possible.
[0009]
Further, at least in both cylinders at both ends in the cylinder arrangement direction, the fuel inlet portion is directed inward in the cylinder arrangement direction, and the length of the supply pipe for both the cylinders which is inherently the longest (as actually required length). It can be shortened.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a diesel engine main body. In the diesel engine main body 1, a cylinder head 2 is provided on a cylinder block (not shown), and a cylinder head cover 3 is provided on the cylinder head 2. It has been.
[0014]
Below the cylinder head 2, a plurality of cylinders 4 formed in a cylinder block are sequentially arranged in the longitudinal direction of the cylinder head 2 (left and right direction in FIG. 3) (see FIG. 3). The upper end opening of each cylinder 4 faces the lower surface of the cylinder head 2.
[0015]
As shown in FIGS. 1 to 3, a camshaft 5 to which a driving force of a crankshaft (not shown) is transmitted is disposed on the cylinder head 2. The camshaft 5 is separated from the cylinder 4 to one side in the width direction of the cylinder head 2 (left side in FIG. 1, upper side in FIG. 3), and is extended in the cylinder arrangement direction (left and right direction in FIG. 3). The cam shaft 5 is rotatably supported by a bearing portion 6 formed on the cylinder head 2 and a cap 7 covered from the upper side. In the supported state, the cam shaft 5 has a height of the axis 5a. Is equal to the upper end surface 2 a of the cylinder head 2.
[0016]
Inside the cylinder head 2, as shown in FIG. 3, for each cylinder 4, there are first and second two intake ports 8, 9 and two exhaust ports (not shown). Are formed respectively. Among these, the first and second intake ports 8 and 9 have respective downstream end openings 10 opened in the cylinder 4 and the respective upstream end openings 11 from the other side surface in the width direction of the cylinder head 2. Open to the outside.
[0017]
In the present embodiment, the first and second intake ports 8 and 9 are both tangential ports, and the height position from the opening of the cylinder 4 is higher than that of the helical intake port or the like. Under this condition, the first intake port 8 slightly turns inwardly in the cylinder arrangement direction, and from the other side surface in the width direction of the cylinder head 2 toward one side in the width direction. The air intake port 9 is longer than the second intake port 9.
[0018]
As shown in FIGS. 3 and 4, the first and second intake ports 8 and 9 are equipped with intake valves 12 and 13, respectively. Each intake valve 12 (13) is provided with its valve shaft 12a (13a) along the axial direction of the cylinder 4, and a valve bridge 14 is provided at the upper end of both valve shafts 12a and 13a. Is straddling. The valve bridge 14 is inclined with respect to the camshaft 5 in a plan view, and the inclination is such that the other end with respect to the intake valve 13 is inward of the cylinder arrangement direction with respect to one end linked to the intake valve 12. The valve bridge 14 in each cylinder 4 is symmetric with respect to the center of the cylinder arrangement direction (see FIG. 3).
[0019]
On the other hand, the exhaust port is equipped with exhaust valves 15 and 16, respectively, as shown in FIGS. Each of the exhaust valves 15 and 16 is also provided with its valve shaft (not shown) along the axial direction of the cylinder 4, and a valve bridge 17 straddles the upper ends of both valve shafts. ing. The valve bridge 17 is also inclined with respect to the camshaft 5 in a plan view. The inclination is one end linked to the exhaust valve 15 and the other end with respect to the exhaust valve 16 is inward in the cylinder arrangement direction. The valve bridge 17 in each cylinder 4 is symmetric with respect to the center of the cylinder arrangement direction. Therefore, in each cylinder 4, the valve bridges 14 and 17 are in a parallel state with a predetermined interval, and the other end portions of both the valve bridges 14 and 17 are inwardly in the cylinder arrangement direction than the one end portions. It is supposed to be on the side.
[0020]
A rocker shaft 18 is disposed between the cam shaft 5 and each cylinder 4 as shown in FIGS. The rocker shaft 18 is positioned higher than the camshaft 5 and extends in the cylinder arrangement direction. The rocker shaft 18 includes a rocker for intake and exhaust for each cylinder 4. -Arms 19, 20 are mounted respectively. Each rocker arm 19 (20) is provided with a roller 21 at one end thereof, and the roller 21 is brought into contact with the cam of the camshaft 5, while the other end is provided with the roller 21. An adjusting screw 22 is provided, and the adjusting screw 22 is in contact with the valve bridge 14 (17). Thus, the rocker arm 19 (20) swings about the rocker shaft 18 by the rotation of the camshaft 5, and the intake valve 12 (13) or the exhaust valve 15 is driven by the swinging force based on the swing. (16) is to be opened and closed.
[0021]
As shown in FIGS. 1 to 4, the cylinder head 2 is provided with a fuel injection valve 23 for each cylinder 4. The fuel injection valve 23 is arranged at the center in the radial direction of the cylinder 4 such that its axis coincides with the axis of the cylinder 4, and a nozzle hole at the tip thereof faces the cylinder 4.
The fuel injection valve 23 includes a solenoid 24 as an actuator at the upper part thereof. The solenoid 24 changes the valve lift so as to inject and non-inject fuel. The solenoid 24 is positioned within the cylinder head cover 3 at a position higher than the rocker shaft 18. It is arranged.
[0022]
As shown in FIGS. 1 to 4, the fuel injection valve 23 has a fuel inlet portion 25 for introducing fuel into the fuel injection valve 23 and a return fuel from the fuel injection valve 23 at the side portion thereof. And a fuel outlet portion 26 through which is introduced. The fuel inlet portion 25 and the fuel outlet portion 26 project along the valve bridge 14 (17) toward the other side in the width direction of the cylinder head 2, and the fuel inlet portion 25 is the fuel outlet portion. It is supposed to be located at a position lower than 26.
[0023]
The fuel inlet 25 is provided with a connector 27 as shown in FIGS. As shown in FIG. 5, a so-called nipple type is adopted for the connector 27, and high liquid tightness is secured based on screwing from the side of the fuel injection valve 23. One of the connectors 27 is held in a state of penetrating through the peripheral wall 2 b in the vicinity of the upper end surface 2 a of the cylinder head 2, and the other of the connectors 27 protrudes outside the cylinder head 2. The connector 27 has a function of connecting the fuel inlet portion 25 and the distribution-type injection pump 29 via the supply pipe 28, and fuel is supplied to the fuel inlet portion 25 with a high pressure by the distribution-type injection pump 29. To be supplied to. The distribution type injection pump 29 is located at a position lower than the upstream end opening 11 of the intake port 8 (9).
[0024]
The fuel / fuel outlet 26 is also provided with a connector 30 as shown in FIGS. As shown in FIG. 6, a so-called eyebolt type is adopted for the connector 30, and the liquid tightness as high as the connector 27 is not secured. This is because the pressure at the fuel outlet 26 is not as high as that at the fuel inlet 25. For this reason, the connector 30 is simply configured based on the above format and is smaller than the connector 27. By utilizing this, the connector 30 can be attached to the fuel outlet 26 by screwing from the side of the fuel injection valve 23 at a position above the upper end surface 2a of the cylinder head 2, and after the attachment. Is to be stored in the cylinder head cover-3 (see FIGS. 1 and 2).
Reference numeral 31 denotes a common return pipe that returns the return fuel returned to the fuel outlet 26 in each cylinder to the fuel tank.
[0025]
Therefore, in the above diesel engine, the second intake port 9 close to the fuel inlet 25 is a tangential port whose height is lower than that of a helical port or the like. Utilizing this, the fuel inlet portion 25 can be disposed in a space corresponding to the lowered height. For this reason, the height position of the fuel inlet portion 25 can be lowered to suppress the overall height, and the distance between the fuel inlet portion 25 and the injection pump 29 can be shortened to reduce the fuel inlet portion 25 and the injection pump. Therefore, the length of the fuel supply pipe 28 connecting the terminal 29 to the terminal 29 can be shortened as much as possible.
[0026]
In the diesel engine, as shown in FIG. 3, the fuel inlets of the plurality of cylinders 4 in the cylinder head 2 are symmetrical with respect to the center in the cylinder arrangement direction, and the cylinder 4 The fuel inlet 25 is directed inward in the cylinder arrangement direction, so that the length of the supply pipe 28 can be shortened. In this case, the lengths of the other supply pipes 28 are determined so as to be equal to the lengths of the supply pipes 28 for both cylinders at both ends of the cylinder arrangement direction that is the longest in nature (actually required length). This is because the supply pressure of the fuel is high, thereby preventing the supply from becoming uneven.
[0027]
In addition, the fuel inlet 25 is disposed below the fuel outlet 26 so that the fuel inlet 25 is as close as possible to the injection pump 29. From this viewpoint, the length of the fuel supply pipe 28 can be shortened. become.
[0028]
Furthermore, since the distribution-type injection pump 29 is used as the injection pump, the properties of the distribution-type injection pump 29 that is reduced in size can be used, and the overall size can be reduced.
[0029]
Furthermore, in the fuel inlet portion 25 that is at a high pressure, the connector 27 must be larger than the connector 30 in the fuel outlet portion 26 in terms of sealing, strength, and the like. The small space in the upper peripheral wall 2b of the cylinder head 2 is held through the upper peripheral wall 2b of the head 2 and can be used as a part of the arrangement space of the connector 27 without being wasted. The connection workability between the pipe 28 and the fuel inlet 25 can be improved. In addition, in this case, since the object to be held by the connector 27 is the upper peripheral wall 2b of the cylinder head 2, it is not unstable as in the cylinder head cover-3, and the connector 27 is stably held.
On the other hand, since the connector 30 is not required until it withstands the pressure of the fuel inlet 25, the connector 30 has a relatively small size and can be accommodated in the cylinder head cover-3. In addition, in this case, since it is housed in the cylinder head cover-3 provided on the upper part of the cylinder head 2, the mounting work is not hindered by the upper peripheral wall 2b of the cylinder head 2, and the mounting workability of the connector 30 is improved. You can also do it.
[0030]
In addition, since a highly liquid-tight connector is used as the connector 27 and a connector having a lower liquid-tightness than the connector 27 is used as the connector 30, the fuel inlet 25 having a high pressure and the pressure as high as the fuel inlet 25 are withstood. As a connector, the fuel outlet portion 26 that is not required can be accurately handled.
[0031]
Furthermore, the camshaft 5 can be lowered by forming the bearing portion 6 of the camshaft 5 on the cylinder head 2, and accordingly, the overall height can be reduced. On the other hand, the space between the valve shaft 12 a (13 a) of the intake valve 12 (13) and the valve shaft of the exhaust valve 15 (16) is effectively used as an arrangement space for the fuel inlet portion 25 and the fuel outlet portion 26. Thus, the space between the intake valve and exhaust valve rocker arms 19 and 20 as the upper space between both valve shafts can be effectively used as the solenoid 24 disposition space.
[0032]
In addition, in this case, since the bearing portion 6 is formed so that the height of the shaft center 5a of the cam shaft 5 is equal to the upper end surface 2a of the cylinder head 2, the cam shaft 5 can be accurately supported. .
[0033]
As mentioned above, although embodiment of invention was described, in the present invention, the following modes are also included.
(1) The intake valve 12 (13) and the exhaust valve 15 (16) are three valves or four valves.
(2) It may be DOHC or SOHC.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a diesel engine according to an embodiment.
FIG. 2 is a view showing a main part of FIG. 1;
FIG. 3 is a plan view illustrating a connection relationship between a fuel inlet portion, a fuel outlet portion, and a distribution type injection pump.
4 is an enlarged view showing a main part of FIG. 3;
FIG. 5 is a simplified cross-sectional view illustrating a connector provided at a fuel inlet.
FIG. 6 is a simplified cross-sectional view illustrating a connector provided at a fuel outlet.
[Explanation of symbols]
1 Diesel engine body 2 Cylinder head 2a Cylinder head upper end surface 3 Cylinder head cover
4 cylinder 5 camshaft 5a camshaft shaft center 6 bearing portion 8 first intake port 9 second intake port 10 downstream end opening 11 upstream end opening 12 intake valve 12a valve shaft 13 intake valve 15 exhaust valve 16 Exhaust Valve 18 Rocker Shaft 19 Intake Valve Rocker Arm 20 Exhaust Valve Rocker Arm 23 Fuel Injection Valve 24 Solenoid 25 Fuel Inlet Port 26 Fuel Outlet Port 27 Connector 28 Supply Pipe 29 Distribution Type Injection Pump 30 Connector

Claims (1)

The cylinder head is provided with a fuel injection valve along the axial direction of the cylinder at a central portion in the radial direction of the cylinder, and a plurality of intake air that opens to the cylinder on the radially outer side of the cylinder from the fuel injection valve A port is formed, and a fuel inlet portion for guiding fuel into the fuel injection valve is provided at a side portion of the fuel injection valve, and the fuel inlet portion and the injection pump are connected via a supply pipe. In the direct injection diesel engine in which an intake valve that opens and closes the intake port is provided in the intake port so that the valve shaft of the intake valve is along the axial direction of the cylinder,
A plurality of the cylinders are arranged in a row,
Among the plurality of cylinders, at least a plurality of intake valves for each cylinder at both ends in the cylinder arrangement direction are arranged so as to approach each other toward the outlet side of the injection pump in the width direction of the cylinder head,
The fuel inlet for each cylinder extends to the injection pump side along the direction in which the intake valve for each cylinder is disposed,
The intake port is a tangential port,
The fuel inlet portion is disposed near the upper side of the tangential port, and the injection pump is positioned at a position lower than the upstream end opening of the intake port in the cylinder head.
This is a direct-injection diesel engine.

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