JP2009133274A - Common rail multi-cylinder engine - Google Patents

Abstract

A common rail mounting and fixing method and a cooling shape improvement.
In a common rail multi-cylinder engine in which an intake manifold 4 is mounted on one side of a cylinder head 3 positioned above a cylinder block 2 with the erection direction of a crankshaft 1 being the front-rear direction, the vicinity of the periphery of the intake manifold 4 is provided. A rail mounting boss 5 for mounting and fixing the arranged common rail 10 is provided at an appropriate position of the intake manifold 4. Further, the common rail 10 is configured to have a conical shape by appropriately increasing the shape so that the cooling air is easily received from the front side near the cooling fan 6 disposed on the front side of the cylinder block 2 to the rear side far from the cooling fan 6.
[Selection] Figure 1

Description

  The present invention relates to a common rail type multi-cylinder engine equipped with a common rail.

Conventionally, in a multi-cylinder engine, an intake manifold is attached to one side of the cylinder head in the front-rear direction, with the crankshaft installation direction as the front-rear direction, and the width direction of the cylinder head perpendicular to the front-rear direction as the lateral direction. Some exhaust manifolds are attached and common rails are installed around the cylinder head. However, because these rails are not sufficiently isolated from the cylinder head, the combustion heat of the engine is transferred to the cylinder head. It is easy to cause damage to the common rail due to overheating. For this reason, by arranging the common rail right next to the intake manifold with a dedicated bracket, etc., the common rail is isolated from the cylinder head by the intake manifold, so the combustion heat of the engine is not easily transmitted to the common rail, and overheating of the common rail is suppressed and damaged. The thing etc. which can prevent are disclosed (for example, refer patent document 1).
JP 2007-92598 A

  As described above, by disposing the common rail right next to the intake manifold, the combustion heat of the engine is isolated from the cylinder head and is difficult to be transmitted to the common rail. Is generally arranged in parallel to the side of the intake manifold, so when removing the intake manifold, it is necessary to remove the common rail. In addition, there is a problem that replacement occurs up to the injector.

  Also, when the common rail is cooled by the engine cooling fan, the temperature of the return fuel that has not been injected into the cylinder tends to rise because the cooling of the common rail is poor on the side far from the cooling fan and the entire common rail is difficult to cool uniformly. Thus, the temperature inside the fuel tank rises, causing problems such as vaporization of the fuel and a decrease in the fuel injection amount.

  Therefore, the present invention suppresses overheating of the common rail and prevents damage, improves the common rail mounting and fixing that does not require simultaneous removal of the common rail, high pressure fuel pipe, etc. when removing the intake manifold, and is provided on the side far from the cooling fan of the common rail. This is to improve cooling.

  The invention according to claim 1 is a common rail type multi-cylinder in which an intake manifold (4) is mounted on one side of a cylinder head (3) located on an upper part of a cylinder block (2) with the erected direction of the crankshaft (1) as a front-rear direction. A common rail type multi-cylinder characterized in that a rail mounting boss (5) for mounting and fixing a common rail (10) disposed in the vicinity of the periphery of the intake manifold (4) is provided at an appropriate position of the intake manifold (4) in the engine. The engine configuration.

  With such a configuration, the common rail (10) is mounted and fixed via the rail mounting boss (5) provided at an appropriate position of the intake manifold (4) mounted on one side of the cylinder head (3). As a result, when it becomes necessary to remove the intake manifold (4) due to maintenance or the like, the fixing of the rail mounting boss (5) and the common rail (10) is released, and the common rail (10) and the related parts are disposed. It is possible to remove only the intake manifold (4).

  The invention of claim 2 is characterized in that the shape of the common rail (10) is formed in a conical shape from the front side close to the cooling fan (6) disposed on the front side of the cylinder block (2) to the rear side far from the cooling fan (6). The configuration of the common rail type multi-cylinder engine according to claim 1.

  With such a configuration, the common rail (10) is cooled by the cooling air from the cooling fan (6) disposed on the front side of the cylinder block (2), and the common rail (10) that directly receives the cooling air during this cooling. The rear side has a conical shape with a diameter that is appropriately larger than the front side so that the cooling air can be applied to the rear side more than the front side. Thus, the entire common rail (10) can be cooled substantially uniformly and efficiently.

  In the first aspect of the invention, as described above, the common rail (10) is attached and fixed to the rail mounting boss (5) provided in the intake manifold (4) joined and mounted to the cylinder head (3). Since it is isolated from the head (3), it is difficult for combustion heat to be transmitted to the common rail (10), and overheating is suppressed and damage can be prevented.

  Also, when removing the intake manifold (4), the rail mounting boss (5) and the common rail (10) are released from the fixed state, and the pipes and the like for sending high-pressure fuel to the common rail (10) and the cylinder side remain in that arrangement. Since only the intake manifold (4) can be removed, the intake manifold (4) can be easily and easily removed. And, unlike the conventional case, there is no need for a dedicated bracket or a screw tap for mounting to the cylinder head (3), and the pipe for sending high-pressure fuel to the cylinder side can be shortened, and a compact layout and cost effectively utilizing space. Can be reduced.

  In the invention of claim 2, when the common rail (10) is cooled by the cooling air from the cooling fan (6) as described above, the diameter of the rear side of the common rail (10) far from the cooling fan (6) is set to the front part. By forming a conical shape that is appropriately increased in size so as to easily receive the cooling air with respect to the side diameter, the cooling air reception on the rear side is improved and the entire common rail (10) is cooled substantially uniformly and efficiently. Therefore, the fuel temperature in the common rail (10) can be lowered to an appropriate temperature, the temperature rise of the return fuel not injected into the cylinder, and the temperature rise in the fuel tank due to the return fuel are suppressed, and the fuel is reduced. It is possible to prevent a decrease in output due to vaporization of fuel or a lean fuel density.

  In a common rail type multi-cylinder diesel engine in which an intake manifold 4 is mounted on one side wall in the front-rear direction of a cylinder head 3 positioned above the cylinder block 2 with the installation direction of the crankshaft 1 being the front-rear direction, Rail mounting bosses 5 for mounting and fixing the arranged common rails 10 are provided at appropriate positions on the intake manifold 4. Further, in the common rail type multi-cylinder diesel engine, the arrangement shape of the common rail 10 is such that the rear side diameter far from the cooling fan 6 arranged on the front side portion of the cylinder block 2 is more susceptible to cooling air than the front side diameter. An appropriate amount is increased to form a cone.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 5, an outline of a multi-cylinder diesel engine E adopting a common rail type (accumulation type fuel injection) will be described with reference to a system diagram. In the common rail type, fuel is supplied to a fuel injection device that injects fuel into each cylinder through a common rail 10 (pressure accumulating chamber) having a required pressure.

  The fuel in the fuel tank 11 is sucked into the high-pressure fuel pump 13 driven by the engine E through the fuel filter 12 through the suction passage, and the high-pressure fuel pressurized by the high-pressure fuel pump 13 is discharged through the discharge passage 14. It is guided to the common rail 10 and stored.

  The high-pressure fuel in the common rail 10 is supplied to the injectors 17 corresponding to the number of cylinders through the high-pressure fuel pipes 15, and the injectors 17 are opened for each cylinder based on commands from the engine control unit 18 (hereinafter referred to as ECU). Then, the high pressure fuel is injected and supplied into each combustion chamber of the engine E, and surplus fuel (return fuel) in each injector 17 is guided to the common return passage 20 by each return passage 19, and fuel is returned by the return passage 20. Returned to the tank 11.

  In addition, a pressure control valve 21 is provided in the high-pressure fuel pump 13 to control the fuel pressure in the common rail 10 (common rail pressure). The pressure control valve 21 receives fuel from the high-pressure fuel pump 13 according to a duty signal from the ECU 18. The flow area of the return passage 20 for surplus fuel to the tank 11 is adjusted, and thereby the fuel discharge amount to the common rail 10 side can be adjusted to control the common rail pressure.

  Specifically, the target common rail pressure is set according to the engine operating conditions, and the common rail pressure is feedback-controlled through the pressure control valve 21 so that the common rail pressure detected by the rail pressure sensor 22 matches the target common rail pressure. .

  Conventionally, in a diesel engine, it is known to perform pilot injection that injects a small amount of fuel in a pulse manner prior to main injection, thereby shortening the ignition delay and reducing the so-called knocking noise unique to the diesel engine. .

  This pilot injection is performed once or twice before the main injection. However, by using the system of the common rail 10, the state of the pilot injection is changed according to the state of the engine. The generation of white smoke or black smoke due to noise reduction or incomplete combustion can be suppressed.

  As shown in FIG. 6, the ECU 18 of the common rail type diesel engine E in an agricultural machine or the like has three control modes of a traveling mode M1, a normal working mode M2, and a heavy working mode M3 in relation to the rotational speed and the output torque. .

  The traveling mode M1 is used when traveling without farming as droop control in which the output fluctuates due to fluctuations in the rotational speed. For example, when the traveling speed is reduced or stopped by applying a brake, As the traveling load increases, the engine speed decreases, so the traveling speed can be reduced or stopped safely.

  The normal work mode M2 is used when performing normal farm work as isochronous control in which the rotation speed is constant and the output is changed according to the load even when the load fluctuates. Sometimes, when the cultivated land is hard and resistance is applied to the cultivating blade, the combine makes it easy for the operator to control the output and maintain the number of rotations even when there is a lot of harvest during harvesting and the load increases.

  In the heavy work mode M3, as in the normal work mode M2, the isochronous control that changes the output according to the load at a constant rotation speed even when the load fluctuates, and when the load limit is approached, the rotation speed is increased to increase the output. Control with heavy load control, especially used when farming near the load limit.For example, when plowing with a tractor, engine output even when encountering hard cultivated land Increases beyond the normal limit, so work is not interrupted.

  These work modes M1, M2, and M3 are configured to be switched by an operation of a work mode changeover switch, a shift operation of a travel shift lever, an operation of turning on and off a work clutch, or the like.

  As shown in FIGS. 7 and 8, the common rail type multi-cylinder diesel engine E has a cylinder head 3 disposed above the cylinder block 2 that supports the crankshaft 1 in the front-rear direction, and an oil pan 7 disposed below. A gear case 8 with a gear train installed in the front and a cooling fan 6 are arranged, and a flywheel 9 is arranged in the rear.

  A glow plug 16 for each cylinder is fitted into the cylinder head 3 from the lower side of the box-shaped intake manifold 4 without a branch pipe connected to the one side wall 3a in the front-rear direction of the cylinder head 3, and The high-pressure fuel pump 13 driven by the gear case 8 is arranged below the lower side, and the turbine side of the turbocharger 24 is connected to the exhaust manifold 23 connected to the other side wall 3b in the front-rear direction of the cylinder head 3. Arranged.

As shown in FIG. 1, a plurality of rail mounting bosses 5 are provided at appropriate positions on the upper surface side of the intake manifold 4 for mounting and fixing the common rail 10 in a substantially parallel posture, and are attached to the rail mounting boss 5 with fastening screws s. The common rail 10 to be fixed and the injector 17 fitted to the cylinder head 3 are separately connected by the high-pressure fuel pipe 15. (See Figs. 7 and 8)
With such a configuration, the common rail 10 is mounted on the rail mounting boss 5 provided on the intake manifold 4, so that the common rail 10 is isolated from the cylinder head 3, so that the combustion heat is not easily transmitted and overheating is suppressed and damaged. In addition, when the intake manifold 4 is removed, it is possible to remove only the intake manifold 4 while leaving the common rail 10 and the high-pressure fuel pipe 15 etc. by releasing the fastening screw s. The high-pressure fuel pipe 15 is also removed from the common rail. Since the distance between 10 and the injector 17 is short, it can be shortened.

  In addition, unlike the prior art, there is no need for a dedicated bracket or the like for mounting the common rail 10, and screw taps for mounting provided on the cylinder head 3 and the head cover 25 are not required, and the space is effectively utilized and is compact. Layout and cost can be reduced.

  However, as described above, since the common rail 10 is fixed to the rail mounting bosses 5 arranged at a plurality of positions on the intake manifold 4 by the fastening screws s, the common rail 10 is removed from the intake manifold 4 by releasing the fastening screws s. However, when the intake manifold 4 is attached to and detached from the cylinder head 3, a plurality of rail mounting bosses 5 are arranged on the intake manifold 4, and the mounting portion 10 a is attached to the common rail 10. There were few gaps, and there was a difficulty in requiring a technical procedure for attaching and detaching the intake manifold 4.

  Therefore, as shown in FIG. 2, the rail mounting boss 5 of the intake manifold 4 is subjected to spot facing, and a collar 26 is inserted between the rail 10 and the mounting portion 10 a of the common rail 10 and is fixed by a tightening screw s. The attachment and detachment of the manifold 4 does not require a technical procedure and can be easily attached and detached.

  Further, as shown in FIG. 3, a side wall of the cylinder head 3 can be used as a method different from the method of inserting the collar 26 between the rail mounting boss 5 of the intake manifold 4 and the mounting portion 10a of the common rail 10 as shown in FIG. The joint rail 27 is provided with a rail attachment boss 27a sandwiched between the joint plate 27 and the intake manifold 4, so that the common rail 10 remains attached and fixed to the joint plate 27, leaving the joint plate 27 and only the intake manifold 4. Can be easily attached to and detached from the cylinder head 3.

Further, the common rail 10 mounted on the common rail type multi-cylinder diesel engine E is cooled by cooling air from the cooling fan 6 arranged on the front side of the cylinder block 2. Since the cylindrical rear portion side of the common rail 10 formed in a shape is far from the cooling fan 6, it is difficult for the cooling air to hit, and it is difficult to cool the entire common rail 10 evenly. (See Figs. 7 and 8)
For this reason, as shown in FIG. 4, the diameter of the rear side is increased so that the cooling air is greatly applied also to the rear side far from the cooling fan 6 with respect to the front side of the common rail 10 that directly receives the cooling air from the cooling fan 6. By forming the conical shape appropriately larger than the diameter on the part side, the cooling air reception on the rear side is improved and the entire common rail 10 can be cooled substantially uniformly and efficiently. The fuel temperature can be lowered to an appropriate temperature, and the temperature rise of the return fuel that was not injected into the cylinder and the temperature rise in the fuel tank due to this return fuel are suppressed to reduce the output due to fuel vaporization and fuel density dilution. Can be prevented.

  Further, in the case where the glow plug 16 for each cylinder is fitted and arranged on the lower side of the side wall of the cylinder head 3, in order to avoid the interference of the glow plug 16 with the intake manifold 4, conventionally, FIG. As shown in FIG. 4, in the case where the cutout portion a is provided in the portion where the glow plug 16 of the intake manifold 4 is disposed, the wall surface of the intake manifold 4 is obstructive and hinders the use of tools when replacing the glow plug 16. Was.

  For this reason, as shown in FIG. 9B, the portion of the intake manifold 4 where the glow plug 16 is disposed is a notch portion b that does not obstruct the wall surface of the intake manifold 4 when using the tool when replacing the glow plug 16. As a result, the maintainability in replacement work such as when the glow plug 16 is disconnected can be improved, and assembly can be easily performed during production.

  Further, as described above, if the intake manifold 4 has the notch a or b for avoiding the interference of the glow plug 16, the rigidity at the position of the notch a or b is lowered, and the cylinder head 3 is moved to the cylinder head 3. When assembling the intake manifold 4, there was a problem that the surface pressure of the combined surface could not be secured.

  For this reason, as shown in FIG. 10 (a), by adding a reinforcing rib e as shown in FIG. 10 (b) to the intake manifold 4 having the notches a or b of the glow plug 16, the engine Since the rigidity of the combination surface of the intake manifold 4 can be increased without affecting the performance, the airtightness between the cylinder head 3 and the intake manifold 4 can be secured, and the durability and reliability can be improved.

  Further, as described above, if the intake manifold 4 has the cutout portion a or b in order to avoid the interference of the glow plug 16, the cutout portion a or b reduces the intake channel cross-sectional area f and throttles the intake air. As a result, engine performance and fuel consumption may be reduced.

  For this reason, as shown in FIGS. 11A and 11B, the intake manifold 4 is divided into an inner portion 4a and an outer portion 4b to cut off the intake flow path for avoiding the interference of the glow plug 16. Since the aperture of the area f can be reduced as much as possible, the engine performance and fuel consumption can be improved.

  In the conventional cylinder block 2, when the cylinder head 3 is tightened with a head bolt, as shown in FIG. 12A, the cylinder bore 2a is greatly deformed around the bolt boss 2b near the side wall of the cylinder block 2. For this reason, the piston ring cannot follow the deformation, and the oil consumption increases or the engine performance such as combustion and exhaust gas is greatly affected.

  For this reason, as shown in FIG. 12B, by providing the vertical rib u on the outer peripheral surface of the cylinder bore 2a adjacent to the bolt boss 2b, the deformation that occurs when the head bolt is tightened is suppressed. As a result, the deformation that the piston ring could not follow can be controlled by the deformation that can follow, resulting in reduced oil consumption, better engine performance and exhaust gas performance, and improved engine durability and reliability. Improvements can be made.

  Further, in the cylinder block 2, conventionally, the cylinder of the cylinder bore 2a has a uniform thickness, and when the cylinder head 3 is tightened with six head bolts per cylinder as shown in FIG. 12 (a), Since the deformation in the side wall direction of the cylinder block 2 is greatly generated, the piston ring cannot follow the deformation, and the engine performance is greatly affected in the same manner as described above.

  For this reason, as shown in FIG. 13, the cylindrical wall shape of the cylinder bore 2a is made into an elliptical shape in which the side wall direction of the cylinder block 2 is partially thick v, so that deformation that occurs when the head bolt is tightened is suppressed and generated. Since the deformed deformation is also dispersed vertically by the thick wall v, and the deformation that the piston ring cannot follow can be controlled to the followable deformation, the same effect as described above can be obtained.

  Further, in the cylinder block 2, conventionally, the bolt boss 2b for tightening the head bolt is connected to the wall surface of the cylinder block 2 with a small radius similar to other corner radiuses. Because the deformation generated locally by pulling or pushing the wall surface becomes a large deformation of the cylinder bore 2a, the piston ring cannot follow the deformation and has a great influence on the engine performance as described above.

  For this reason, as shown in FIG. 14, the bolt boss 2b for tightening the head bolt is reinforced by a large rounded reinforcing body w between the wall surface of the cylinder block 2 and the wall surface of the cylinder bore 2a. The deformation that occurs sometimes is absorbed and dispersed in a wide range by the reinforcing body w on the wall surface of the cylinder block 2, and as a result, the deformation that the piston ring could not follow can be controlled to the followable deformation. Advantageous effects can be obtained.

  Further, as shown in FIG. 15, in the engine F equipped with the combine, the cooling fan 28 is disposed at the front of the engine F, the flywheel 29 is disposed at the rear, and the discharge fan 30 is disposed at the rear surface of the flywheel 29. Thus, the cooling air sent from the front cooling fan 28 can be discharged backward by the discharge fan 30, and the air flow at the rear of the engine can be rectified to efficiently discharge the heat outside the engine room. The temperature inside can be lowered.

  Further, unlike the case where the discharge fan 30 is disposed and mounted on the rear surface of the flywheel 29 as described above, the fan blade 31 is mounted and disposed on the outer periphery of the flywheel 29 as shown in FIG. The cooling air sent from the engine 28 is exhausted backward by the fan blade 31, and the air flow at the rear of the engine can be rectified to efficiently exhaust the heat outside the aircraft. Can do.

  It can be used for farm vehicles such as tractors and combiners as well as general vehicles.

The rear view which shows the state which clamped and fixed the common rail to the intake manifold. The rear view which shows the state which clamped and fixed the common rail to the intake manifold. The rear view which shows the state which clamped and fixed the common rail to the intake manifold. The side view which shows the conical state which made the common rail larger the one end side than the one end side. The system figure which shows the pressure accumulation type fuel injection diesel engine by a common rail. The diagram which shows the relationship between the engine speed and output torque by three types of control modes. The side view which shows the whole structure in a common rail type | mold multi-cylinder diesel engine. The top view which shows the whole structure in a common rail type | mold multi-cylinder diesel engine. (A) Back sectional drawing which shows the state which provided the notch part for glow plugs of an intake manifold.

(B) The back sectional view showing the state where the cutout part for the glow plug of the intake manifold was provided.
(A) The perspective view which shows the state without a reinforcement rib in the glow plug notch part of an intake manifold.

(B) The perspective view which shows the reinforcement rib provided in the glow plug notch part of the intake manifold.
(A) Back sectional drawing which shows the state which makes an intake manifold a split type and increases an intake flow path.

(B) The perspective view which shows the state which increases an intake flow path by making an intake manifold into a split type.
(A) The perspective view which shows the state which has arrange | positioned the bolt boss at the time of tightening a cylinder head.

(B) The perspective view which shows a vertical rib arrangement | positioning state on the cylinder bore outer peripheral surface close to a bolt boss.
The perspective view which shows the state which makes the cylindrical wall pressure shape of a cylinder bore partially thick. The perspective view which shows the state which reinforces a bolt boss | hub by the reinforcement body of a big round. The top view which shows the state which provided the cooling fan before and behind the engine for combines. The top view which shows the state which provided the cooling fan before and behind the engine for combines.

Explanation of symbols

1 Crankshaft 2 Cylinder Block 3 Cylinder Head 4 Intake Manifold 5 Rail Mounting Boss 6 Cooling Fan 10 Common Rail

Claims (2)

  In a common rail type multi-cylinder engine in which an intake manifold (4) is mounted on one side of a cylinder head (3) positioned above a cylinder block (2) with the erected direction of the crankshaft (1) as a longitudinal direction, the intake manifold ( 4) A common rail type multi-cylinder engine characterized in that a rail mounting boss (5) for mounting and fixing a common rail (10) disposed in the vicinity of 4) is provided at an appropriate position of the intake manifold (4).   The shape of the common rail (10) is formed in a conical shape from the front side near the cooling fan (6) disposed on the front side of the cylinder block (2) to the rear side far from the cooling fan (6). Common rail type multi-cylinder engine.

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