JP7559166B2 - Engine equipment - Google Patents

Description

This invention relates to an engine device equipped with a common rail.

In recent years, common rails have come to be used in diesel engines due to increased injection pressures in response to exhaust gas regulations and increased demands for low fuel consumption (see, for example, Patent Documents 1 and 2). The common rail stores fuel supplied from a fuel tank at high pressure. The pressure inside the common rail is regulated by a pressure reducing valve attached to the common rail. Fuel discharged from the pressure reducing valve is returned to the fuel tank via a fuel return pipe (also called a leak pipe) connected to the pressure reducing valve.

Patent No. 4074860 JP 2007-139098 A

In common rails, fuel is used to lubricate the sliding parts of the pressure reducing valve. Conventionally, in order to immerse the sliding parts of the pressure reducing valve in fuel, the mounting angle of the common rail on the engine device (the direction in which the fuel return pipe connection part protrudes) is ensured to be in the range of 45 degrees to 90 degrees upward from the horizontal. Furthermore, when the mounting angle is within the range of 0 degrees to 45 degrees, the fuel return pipe is attached to the fuel return pipe connection part facing upward. Thus, there are restrictions on the direction in which the fuel return pipe can be connected to the common rail, which creates a problem in that there are restrictions on the mounting conditions of the common rail.

The technical objective of the present invention is to provide an engine device that has been improved based on the current situation described above.

The engine device of the present invention is an engine device equipped with a common rail that stores fuel supplied from a fuel supply pump at high pressure, and a fuel return pipe that returns fuel in the common rail to the fuel supply pump is connected to the common rail, and the fuel return pipe is fixed at a position higher than the common rail and connected to the fuel supply pump that is located below the common rail.

In the engine device of the present invention, an intake manifold may be provided in the cylinder head, and the fuel return pipe may be disposed below the intake manifold.

Furthermore, an exhaust gas recirculation device that mixes a portion of the exhaust gas discharged from the exhaust manifold into fresh air may be connected to the intake manifold, and the fuel return pipe may be attached to the exhaust gas recirculation device at a position higher than the common rail.

In the engine device of the present invention, a fuel pipe may be connected to the common rail on the side opposite to the side to which the fuel return pipe is connected, and the fuel pipe may be connected to the fuel supply pump.

Furthermore, an oil cooler may be disposed below the intake manifold, and the fuel return pipe may be disposed in front of the oil cooler.

The engine device of the present invention relaxes the common rail installation requirements and improves the freedom of design of the engine device.

FIG. 1 is a schematic front view of an embodiment of an engine apparatus. FIG. FIG. 2 is a schematic left side view of the embodiment. FIG. FIG. FIG. 2 is an explanatory diagram of a fuel system according to the embodiment. 2 is an enlarged schematic front view showing the periphery of the common rail of the embodiment; FIG. FIG. 2 is an enlarged schematic left side view showing the common rail and its periphery. FIG. 2 is an enlarged schematic plan view showing the common rail and its periphery. 10 is a schematic rear view of the embodiment taken along the line AA in FIG. 9. FIG. 2 is a schematic front view showing an enlarged view of the periphery of a right front corner of the embodiment. FIG. 2 is a schematic plan view showing an enlarged view of the periphery of a right front corner of the embodiment. FIG. 2 is a schematic perspective view showing an enlarged view of the periphery of a right front corner of the embodiment. FIG. 13 is a schematic rear view of another embodiment.

Below, an embodiment of the present invention will be described with reference to the drawings. First, the overall structure of engine 1, which is an example of an engine device, will be described with reference to Figs. 1 to 5. In this embodiment, engine 1 is a diesel engine. In the following description of engine 1, both sides parallel to crankshaft 5 (both sides sandwiching crankshaft 5) will be referred to as the left and right, the side where flywheel housing 7 is installed will be referred to as the front side, and the side where cooling fan 9 is installed will be referred to as the rear side, and for convenience, these will be used as the basis for the positional relationships of the four sides and the top and bottom of engine 1.

As shown in Figures 1 to 5, an intake manifold 3 is disposed on one side of the engine 1 parallel to the crankshaft 5, and an exhaust manifold 4 is disposed on the other side. In this embodiment, the intake manifold 3 is molded integrally with the cylinder head 2 on the right side thereof. The exhaust manifold 4 is installed on the left side of the cylinder head 2. The cylinder head 2 is mounted on a cylinder block 6 that houses the crankshaft 5 and pistons (not shown).

The front and rear ends of the crankshaft 5 protrude from both the front and rear side surfaces of the cylinder block 6. A flywheel housing 7 is fixed to one side of the engine 1 that intersects with the crankshaft 5 (the front side surface of the cylinder block 6 in this embodiment). A flywheel 8 is disposed within the flywheel housing 7. The flywheel 8 is fixed to the front end side of the crankshaft 5 and is configured to rotate integrally with the crankshaft 5. The engine 1 is configured to extract power from the flywheel 8 to a working part of a work machine (e.g., a hydraulic excavator, a forklift, etc.). A cooling fan 9 is provided on the other side of the engine 1 that intersects with the crankshaft 5 (the rear side surface of the cylinder block 6 in this embodiment). The rotational force is transmitted from the rear end side of the crankshaft 5 to the cooling fan 9 via a belt 10.

An oil pan 11 is disposed on the underside of the cylinder block 6. Lubricating oil is stored in the oil pan 11. The lubricating oil in the oil pan 11 is sucked up by a lubricating oil pump (not shown) disposed on the right side of the cylinder block 6, which is the connecting portion between the cylinder block 6 and the flywheel housing 7, and is supplied to each lubricated part of the engine 1 via an oil cooler 13 and an oil filter 14 disposed on the right side of the cylinder block 6. The lubricating oil supplied to each lubricated part is then returned to the oil pan 11. The lubricating oil pump is configured to be driven by the rotation of the crankshaft 5.

As shown in FIG. 4, a fuel supply pump 15 for supplying fuel is attached to the right side of the engine 1 at the connection with the flywheel housing 7 of the cylinder block 6. The fuel supply pump 15 is disposed below the EGR device (exhaust gas recirculation device) 24. A common rail 16 is disposed between the intake manifold 3 of the cylinder head 2 and the fuel supply pump 15. The common rail 16 is fixed to the upper front portion of the right side of the cylinder block 6. Injectors 17 (see FIG. 6) for each of the four cylinders, each having an electromagnetically controlled fuel injection valve, are provided on the top surface of the cylinder head 2, which is covered by the cylinder head cover 18.

Each injector 17 is connected to a fuel tank 201 (see FIG. 6) mounted on the work vehicle via a fuel supply pump 15 and a generally cylindrical common rail 16. Fuel in the fuel tank 201 is pumped from the fuel supply pump 15 to the common rail 16, and high-pressure fuel is stored in the common rail 16. By controlling the opening and closing of the fuel injection valves of each injector 17, the high-pressure fuel in the common rail 16 is injected from each injector 17 into each cylinder of the engine 1.

As shown in FIG. 2 and FIG. 5, a blow-by gas reduction device 19 is provided on the upper surface of a cylinder head cover 18 that covers an intake valve and an exhaust valve (not shown) provided on the upper surface of the cylinder head 2. The blow-by gas reduction device 19 takes in blow-by gas that has leaked from the combustion chamber of the engine 1 to the upper surface side of the cylinder head 2.
A blow-by gas outlet of the blow-by gas reduction device 19 is connected to an intake part of the two-stage turbocharger 30 via a return hose 68. The blow-by gas from which the lubricating oil components have been removed in the blow-by gas reduction device 19 is returned to the intake manifold 3 via the two-stage turbocharger 30 etc.

As shown in FIG. 3, on the left side of the engine 1, an engine starter 20 is attached to the flywheel housing 7. The engine starter 20 is disposed below the exhaust manifold 4. The engine starter 20 is attached to the left side of the rear side of the flywheel housing 7, below the connection between the cylinder block 6 and the flywheel housing 7.

As shown in FIG. 2, a cooling water pump 21 for cooling water lubrication is disposed on the left side of the rear side of the cylinder block 6. An alternator 12 is provided to the left of the cooling water pump 21 as a generator that generates electricity using the power of the engine 1. Rotational power is transmitted from the front end of the crankshaft 5 via a belt 10 to the cooling fan 9, the alternator 12, and the cooling water pump 21. Cooling water in a radiator (not shown) mounted on the work vehicle is supplied to the cooling water pump 21 by driving the cooling water pump 21. Cooling water is then supplied to the cylinder head 2 and the cylinder block 6 to cool the engine 1.

As shown in FIG. 3, the cooling water pump 21 is disposed at a lower height than the exhaust manifold 4, and the cooling water inlet pipe 22, which is connected to the cooling water outlet of the radiator, is fixed to the left side surface of the cylinder block 6 at approximately the same height as the cooling water pump 21. On the other hand, the cooling water outlet pipe 23, which is connected to the cooling water inlet of the radiator, is fixed to the right rear portion of the upper surface of the cylinder head 2, as shown in FIG. 2 and FIG. 5. The cylinder head 2 has a cooling water drain 35 at its right rear corner, and the cooling water outlet pipe 23 is installed on the upper surface of the cooling water drain 35.

As shown in Figures 4 and 5, the EGR device 24 is disposed on the right side of the cylinder head 2. The EGR device 24 has a collector 25 as a relay pipe that mixes the recirculated exhaust gas (EGR gas from the exhaust manifold 4) of the engine 1 with fresh air (external air from the air cleaner) and supplies it to the intake manifold 3, an intake throttle member 26 that connects the collector 25 to the air cleaner, a recirculated exhaust gas pipe 28 that is part of the return pipe that connects to the exhaust manifold 4 via an EGR cooler 27, and an EGR valve member 29 that connects the collector 25 to the recirculated exhaust gas pipe 28.

In this embodiment, the collector 25 of the EGR device 24 is connected to the right side of the intake manifold 3, which is molded integrally with the cylinder head 2 and forms the right side of the cylinder head 2. That is, the outlet opening of the collector 25 is connected to the inlet opening of the intake manifold 3 provided on the right side of the cylinder head 2. Also, the EGR gas inlet of the recirculated exhaust gas piping 28 is connected to the EGR gas outlet of the EGR gas passage provided in the cylinder head 2 at a forward portion of the right side of the cylinder head 2. The collector 25 is attached to the intake manifold 3 and the recirculated exhaust gas piping 28 is attached to the cylinder head 2, whereby the EGR device 24 is fixed to the cylinder head 2.

In the EGR device 24, the intake manifold 3 and the intake throttle member 26 for introducing fresh air are connected through the collector 25. The collector 25 is connected to an EGR valve member 29 that is connected to the outlet side of the recirculated exhaust gas pipe 28. The collector 25 is formed in a generally cylindrical shape that is longitudinal from front to rear. The intake throttle member 26 is bolted to the intake side (front side in the longitudinal direction) of the collector 25. The intake and exhaust side of the collector 25 is bolted to the inlet side of the intake manifold 3. The EGR valve member 29 adjusts the opening of the EGR valve inside it to adjust the amount of EGR gas supplied to the collector 25.

Fresh air is supplied to the collector 25, and EGR gas (a part of the exhaust gas discharged from the exhaust manifold 4) is supplied to the collector 25 from the exhaust manifold 4 via the EGR valve member 29. After the fresh air and the EGR gas from the exhaust manifold 4 are mixed in the collector 25, the mixed gas in the collector 25 is supplied to the intake manifold 3. In other words, by returning a part of the exhaust gas discharged from the engine 1 to the exhaust manifold 4 from the intake manifold 3 to the engine 1, the maximum combustion temperature during high load operation is lowered, and the amount of NOx (nitrogen oxides) emitted from the engine 1 is reduced.

As shown in Figures 1 and 3 to 5, the EGR cooler 27 is fixed to the front side of the cylinder head 2. Cooling water and EGR gas flowing inside the cylinder head 2 flow in and out of the EGR cooler 27, and the EGR gas is cooled inside the EGR cooler 27. A pair of left and right EGR cooler connecting parts 33, 34 that connect the EGR cooler 27 are protruding from the front side of the cylinder head 2. The left EGR cooler connecting part 33 is protruding forward from the left front corner of the cylinder head 2. The right EGR cooler connecting part 34 is spaced from the left EGR cooler connecting part 33 and protruding forward from the right front corner of the cylinder head 2. The EGR cooler 27 is connected to the front sides of the EGR cooler connecting parts 33, 34. That is, the EGR cooler 27 is disposed above the flywheel housing 7 and in front of the cylinder head 2, with the rear side of the EGR cooler 27 separated from the front side of the cylinder head 2.

As shown in Figures 1 to 3 and 5, a two-stage turbocharger 30 is disposed on the left side of the cylinder head 2. The two-stage turbocharger 30 includes a high-pressure stage turbocharger 51 and a low-pressure stage turbocharger 52. The high-pressure stage turbocharger 51 includes a high-pressure stage turbine case 53 incorporating a turbine wheel (not shown) and a high-pressure stage compressor case 54 incorporating a blower wheel (not shown). The low-pressure stage turbocharger 52 includes a low-pressure stage turbine case 55 incorporating a turbine wheel (not shown) and a low-pressure stage compressor case 56 incorporating a blower wheel (not shown).

In the exhaust path of the two-stage turbocharger 30, the high-pressure stage turbine case 53 is connected to the exhaust manifold 4, the low-pressure stage turbine case 55 is connected to the high-pressure stage turbine case 53 via a high-pressure exhaust gas pipe 59, and the low-pressure stage turbine case 55 is connected to an exhaust connecting pipe 119. The high-pressure exhaust gas pipe 59 is formed of a flexible pipe. In this embodiment, a portion of the high-pressure exhaust gas pipe 59 is formed in a bellows shape.

A tail pipe (not shown) is connected to the exhaust manifold 119 via an exhaust gas purification device (not shown) and the like. Exhaust gas discharged from each cylinder of the engine 1 into the exhaust manifold 4 passes through the two-stage turbocharger 30 and the exhaust gas purification device and is released to the outside from the tail pipe.

In the intake path of the two-stage turbocharger 30, the low-pressure compressor case 56 is connected to the air cleaner via an intake pipe 62, the high-pressure compressor case 54 is connected to the low-pressure compressor case 56 via a low-pressure fresh air passage pipe 65, and the intake throttle member 26 of the EGR device 24 is connected to the high-pressure compressor case 54 via an intercooler (not shown). Fresh air (outside air) sucked into the air cleaner is cleaned and purified by the air cleaner, then sent to the intake manifold 3 via the two-stage turbocharger 30, the intercooler, the intake throttle member 26, the collector 25, etc., and is then supplied to each cylinder of the engine 1.

Next, the common rail system 200 and the fuel system structure of the engine 1 will be described with reference to FIG. 6. A fuel tank 201 is connected to each of the injectors 17 for four cylinders provided in the engine 1 via a fuel supply pump 15 and the common rail system 200. Each injector 17 has an electromagnetically controlled fuel injection valve 17a. The common rail system 200 has a generally cylindrical common rail 16.

The fuel tank 201 is connected to the intake side of the fuel supply pump 15 via a fuel supply pipe 210, a fuel filter 202, and a fuel supply low pressure pipe 203. On the other hand, the common rail 16 is connected to the discharge side of the fuel supply pump 15 via a fuel supply high pressure pipe 204. A high pressure pipe connection part 205 is provided near one longitudinal end of the common rail 16. An end of the fuel supply high pressure pipe 204 is connected to the high pressure pipe connection part 205 by screwing a high pressure pipe connector nut 206. The fuel in the fuel tank 201 is sucked into the fuel supply pump 15 via the fuel filter 202 and the fuel supply low pressure pipe 203, and is pumped from the fuel supply pump 15 to the common rail 16 via the fuel supply high pressure pipe 204.

The common rail 16 is connected to the injectors 17 for each of the four cylinders via four fuel injection pipes 207. Fuel injection pipe connection sections 208 for the four cylinders are provided at intervals along the longitudinal direction of the cylindrical common rail 16. The ends of the fuel injection pipes 207 are connected to the fuel injection pipe connection sections 208 by screwing injection pipe connector nuts 209.

A pressure reducing valve 211 is attached to the end face of the other end opposite the one end of the common rail 16. The pressure reducing valve 211 discharges fuel in the common rail 16 from a fuel return pipe connection part 212 provided on the other end side of the outer circumferential surface of the common rail 16, via a fuel return pipe connection member 213, to a common rail surplus fuel return pipe 214. The common rail surplus fuel return pipe 214 connects the fuel return pipe connection member 213 to a return pipe joint member 215 for discharging surplus fuel from the fuel supply pump 15.

A return pipe joint member 216 for returning surplus fuel is provided on the end face of the one end side of the common rail 16. The fuel discharged from the common rail 16 by the operation of the pressure reducing valve 211 and the surplus fuel of the fuel supply pump 15 are sent to the return pipe joint member 216 via the return pipe joint member 215 and the pump surplus fuel return pipe 217. In addition, the surplus fuel of each injector 17 is sent to the return pipe joint member 216 via the injector surplus fuel return pipe 218. The surplus fuel that is joined at the return pipe joint member 216 is collected in the fuel tank 201 via the fuel return pipe 219. Although not shown in FIG. 6, the middle part of the fuel return pipe 219 is connected to a return pipe connection part 220 (see FIG. 12) provided on the upper part of the fuel filter 202.

A fuel pressure sensor 601 is attached to the common rail 16 to detect the fuel pressure in the common rail 16. Under the control of the engine controller 600, the fuel pressure in the common rail 16 is monitored from the output of the fuel pressure sensor 601, and the opening degree of the intake metering valve 602 of the fuel supply pump 15 is adjusted. Then, while the fuel intake amount of the fuel supply pump 15, and thus the fuel discharge amount, are adjusted, fuel from the fuel tank 201 is pumped by the fuel supply pump 15 to the common rail 16, and the high-pressure fuel is stored in the common rail 16.

The engine controller 600 controls the opening and closing of each fuel injection valve 17a, and the high-pressure fuel in the common rail 16 is injected from each injector 17 into each cylinder of the engine 1. That is, by electronically controlling each fuel injection valve 17a, the injection pressure, injection timing, and injection period (injection amount) of the fuel supplied from each injector 17 can be controlled with high precision. Therefore, nitrogen oxides (NOx) emitted from the engine 1 can be reduced, and the noise and vibration of the engine 1 can be reduced. The engine controller 600 is also electrically connected to an electromagnetically driven pressure reducing valve 211 that adjusts the fuel pressure in the common rail 16 and a fuel temperature sensor 604 that detects the fuel temperature in the fuel supply pump 15. Although not shown, the engine controller 600 is also electrically connected to other devices, such as various sensors provided in the engine 1.

Next, the layout of the common rail 16 will be described with reference to Figures 7 to 13, etc. The roughly cylindrical common rail 16 is attached to the upper front portion of the right side of the cylinder block 6, with its longitudinal direction aligned with the axial direction of the crankshaft 5 (see Figure 1, etc.). The common rail 16 is located below the intake manifold 3, which is molded integrally with the cylinder head 2 on the right side of the cylinder head 2. A pressure reducing valve 211 is attached to the rear end of the common rail 16.

A high-pressure pipe connection 205, four fuel injection pipe connections 208, and a fuel return pipe connection 212 protrude from the right side of the outer circumferential surface of the common rail 16. These connections 205, 208, and 212 protrude toward the right side, and in this embodiment, protrude approximately horizontally. That is, in this embodiment, the common rail 16 is attached to the engine 1 at an installation angle of 0 degrees. The high-pressure pipe connection 205 is disposed in a forward portion of the common rail 16. The fuel return pipe connection 212 is disposed in a rearward portion of the common rail 16. The four fuel injection pipe connections 208 are disposed at equal intervals between the fuel return pipe connection 212 and the fuel return pipe connection 212.

10, one end (upstream end of the fuel flow) of the common rail surplus fuel return pipe 214 is connected to the fuel return pipe connection part 212 via a fuel return pipe connection member 213. The fuel return pipe 214 is led horizontally to the right side from the fuel return pipe connection part 212, then curved diagonally upward to the right and led to a position higher than the pressure reducing valve 211. In this embodiment, the fuel return pipe 214 is led to the vicinity of the front lower part of the collector 25 of the EGR device 24, and is attached to the lower right corner of the back surface of the front flange part 25a of the collector 25 by a pipe attachment member 221. Furthermore, the fuel return pipe 214 is curved diagonally downward from a position near the front lower part of the collector 25, and is connected to a return pipe joint member 215 provided on the right side of the fuel supply pump 15. The fuel return pipe connection member 213 is attached to the fuel return pipe connection part 212 so that it protrudes approximately horizontally to the right from the fuel return pipe connection part 212.

In this embodiment, the common rail surplus fuel return pipe 214 is led from the pressure reducing valve 211 to a position higher than the pressure reducing valve 211, and then led to a position lower than the pressure reducing valve 211. Therefore, regardless of the mounting angle of the common rail 16 and the connection direction of the fuel return pipe 214 to the common rail 16, fuel can be stored between the part of the fuel return pipe 214 higher than the pressure reducing valve 211 and the pressure reducing valve 211. This ensures that the pressure reducing valve 211 is immersed in fuel, preventing abnormal wear of the sliding parts of the pressure reducing valve 211. Furthermore, the mounting conditions for the common rail 16 are relaxed, and the degree of freedom in designing the engine 1 is improved.

In addition, since the middle part of the fuel return pipe 214 is attached to the collector 25 of the EGR device 24 at a position higher than the pressure reducing valve 211, there is no need to provide the engine 1 with a dedicated part for supporting the middle part of the fuel return pipe 214, and the manufacturing cost of the engine 1 can be suppressed. In addition, by arranging the common rail 16 below the highly rigid intake manifold 3, the common rail 16 can be arranged compactly and the common rail 16 can be physically protected by preventing foreign objects from coming into contact with the common rail 16 from above.

As shown in Figures 7 to 10, the front end of the common rail 16 is disposed on the flywheel housing 7. A return pipe joint member 216 for returning surplus fuel that joins multiple fuel return paths is attached to the front end of the common rail 16. The return pipe joint member 216 is disposed on the flywheel housing 7. By disposing one end (front end) of the common rail 16 above the flywheel housing 7, the area occupied by the arrangement region of the common rail 16 on the right side of the cylinder block 6 can be reduced compared to a configuration in which the entire common rail 16 is disposed on the right side of the cylinder block 6. Therefore, the degree of freedom in the layout of other components on the right side of the cylinder block 6 can be improved. For example, in the engine 1 of this embodiment, the oil cooler 13 is disposed on the rear side of the common rail 16, and the oil cooler 13 is disposed close to the intake manifold 3 and the EGR device 24, thereby realizing a compact arrangement configuration of these components.

As shown in FIG. 7, the return pipe joint member 216 has a connection part 217a to which one end of the pump surplus fuel return pipe 217 is connected, a connection part 218a to which one end of the injector surplus fuel return pipe 218 is connected, and a connection part 219a to which one end of the fuel return pipe 219 (see FIG. 12) is connected. Inside the return pipe joint member 216, there is an internal flow path (not shown) that connects the connection parts 217a, 218a, and 219a, and a fuel pressure regulating valve (not shown) arranged between the internal flow path and the internal space of the common rail 16.

The cylinder head 2 is also provided with an excess fuel outlet 218b (see FIG. 7) near the corner where the right side and front side of the cylinder head 2 intersect. The excess fuel outlet 218b is provided near the upper front end of the right side of the cylinder head 2, and constitutes a part of the injector excess fuel return pipe 218. The excess fuel outlet 218b discharges excess fuel from the injector 17 (see FIG. 6) arranged in the cylinder head 2 to the outside of the cylinder head 2. The injector excess fuel return pipe 218c is connected between the excess fuel outlet 218b and the connection part 218a of the return pipe joint member 216. The excess fuel outlet 218b is connected to the excess fuel outlet 218b of each injector 17 (see FIG. 6) through an excess fuel passage (not shown) formed inside the side wall of the cylinder head 2.

As shown in Figures 7 to 10, the four fuel injection pipes 207 attached to the four fuel injection pipe connections 208 by the injection pipe connector nuts 209 are each led horizontally from the fuel injection pipe connections 208 to the right and below the EGR device 24. Then, each fuel injection pipe 207 is curved toward the cylinder block 6 below the EGR device 24, and then curved upward, passing between the cylinder head 2 and the EGR device 24 and led to the right side of the cylinder head cover 18. As shown in Figures 8, 9, and 13, the mid-way portions of the four fuel injection pipes 207 are attached to the cylinder head 2 by a pair of front and rear fuel injection pipe fixtures 614, 614 attached to the right side of the cylinder head 2.

Two fuel injection pipes 207 are fixed to each fuel injection pipe fixture 614, 614. The mid-way portions of the two fuel injection pipes 207 on the front side of the engine 1 are fixed by the front fuel injection pipe fixture 614 to the end face of a protrusion 615 that protrudes toward the right side of the right side of the cylinder head 2 in front of the intake manifold 3. The mid-way portions of the two fuel injection pipes 207 on the rear side of the engine 1 are fixed by the rear fuel injection pipe fixture 614 to the right side of the intake manifold 3 that is integrally molded with the right side of the cylinder head 2.

Since each fuel injection pipe 207 passes between the cylinder head 2 and the EGR device 24, the fuel injection pipe 207 can be protected by the EGR device 24. This prevents the fuel injection pipe 207 from coming into contact with other components or being deformed by falling foreign objects when the engine 1 is transported, and prevents problems such as fuel leaks caused by damage to the fuel injection pipe 207.

In addition, by fixing the middle portions of the fuel injection pipes 207 to the cylinder head 2, vibration of the fuel injection pipes 207 is reduced, and damage to the fuel injection pipes 207 due to vibration is prevented. In addition, in this embodiment, of the four fuel injection pipes 207, the middle portions of the two fuel injection pipes 207 on the rear side of the engine 1 are fixed to the robust intake manifold 3 by the rear fuel injection pipe fixing device 614, so these fuel injection pipes 207 can be firmly fixed. In this embodiment, the intake manifold 3 is integrally molded with the cylinder head 2, so the fuel injection pipes 207 can be fixed more firmly.

As shown in Figures 7 to 10, one end of a high-pressure fuel supply pipe 204 that connects to the common rail 16 is connected to the upper right side of the fuel supply pump 15. The high-pressure fuel supply pipe 204 is led from the upper right side of the fuel supply pump 15 toward the right side, then curved diagonally upward and forward, and further curved toward the upper front portion of the right side of the cylinder block 6. The high-pressure fuel supply pipe 204 then passes below the EGR device 24 and is led to a high-pressure pipe connection part 205 of the common rail 16. The other end of the high-pressure fuel supply pipe 204 is connected to the high-pressure pipe connection part 205 by a high-pressure pipe connect nut 206.

The fuel supply high-pressure pipe 204, the four fuel injection pipes 207, and the common rail surplus fuel return pipe 214 pass below the EGR device 24, and are therefore protected by the EGR device 24 from contact with foreign objects from above. This reduces damage to the fuel supply high-pressure pipe 204, the fuel injection pipes 207, and the fuel return pipe 214, improving the reliability of the engine 1.

As shown in Figures 7 to 10, the high-pressure pipe connection 205, the four fuel injection pipe connection 208, and the fuel return pipe connection 212 are provided to protrude substantially horizontally from the right side of the outer circumferential surface of the common rail 16 toward the right. Furthermore, no connection parts for connecting piping are provided on the upper or left side of the outer circumferential surface of the common rail 16. Therefore, the common rail 16 can be disposed close to the underside of the intake manifold 3 and the right side of the cylinder block 6, which allows the common rail 16 to be protected by the intake manifold 3 and to be disposed compactly on the engine 1.

As shown in Figures 5 and 11 to 13, a fuel filter 202 is provided in the upper right front portion of the engine 1. The fuel filter 202 is located above the right portion of the flywheel housing 7 and is attached to the right front corner of the cylinder head 2 via a filter mounting bracket 231. By arranging the fuel filter 202 in the empty space above the flywheel housing 7, the fuel filter 202 can be arranged compactly in the engine 1, making it possible to make the engine 1 more compact.

The upper left edge of the fuel filter 202 is fixed to the right front part of the upper surface of the filter mounting bracket 231 with two bolts 232, 233 at the front and rear. The filter mounting bracket 231 is fixed to the right EGR cooler connecting part 34 with bolts 234, 235 attached to bolt mounting holes 234a, 235a (see FIG. 9) on the upper surface of the right EGR cooler connecting part 34 and bolt 2346 attached to bolt mounting hole 236a (see FIG. 7) on the front side surface of the right edge part 34a of the right EGR cooler connecting part 34. By fixing the filter mounting bracket 231 to the upper surface and front side surface of the right EGR cooler connecting part 34 of the cylinder block 6, the filter mounting bracket 231 can be firmly fixed to the cylinder block 6, and thus the fuel filter 202 can be firmly fixed to the cylinder block 6.

As shown in Figures 11 to 13, the return pipe joint member 215 provided on the right side of the fuel supply pump 15 is connected to a connection portion 217a of a return pipe joint portion 216 attached to the front end portion of the common rail 16 via a pump surplus fuel return pipe 217. The connection portion 218a of the return pipe joint portion 216 is connected to a surplus fuel outlet 218b (see Figure 7) provided at the right front corner portion of the cylinder head 2 via an injector surplus fuel return pipe 218c extending in the vertical direction. The connection portion 219a of the return pipe joint portion 216 is connected to the fuel tank 201 (see Figure 6) via an upstream fuel return pipe 219b, a return pipe connection portion 220 provided at the top of the fuel filter 202, and a downstream fuel return pipe 219c. In addition, a fuel supply pipe 210 that connects to the fuel tank 201 and a low-pressure fuel supply pipe 203 that connects to the lower right side of the fuel supply pump 15 are also connected to the upper part of the fuel filter 202.

In this embodiment of the engine 1, the fuel supply pump 15, the common rail 16, and the fuel filter 202 are arranged in one corner of the engine 1 (here, the right front corner). In addition, the pump surplus fuel return pipe 217, the injector surplus fuel return pipe 218c, and the upstream fuel return pipe 219b are connected to a fuel return pipe connection part 216 for returning surplus fuel provided at one end (front end) of the common rail 16. This allows the fuel return pipes 217, 218c, and 219b to be concentrated in one corner of the engine 1, making the piping length shorter and simpler. Furthermore, by concentrating the fuel supply pump 15, the common rail 16, and the fuel filter 202 in one corner of the engine 1, the piping length of the piping connecting them (the fuel supply low pressure pipe 203, the fuel supply high pressure pipe 204, and the common rail surplus fuel return pipe 214) can be shortened and simplified.

As shown in FIG. 10, the engine 1 is an engine device equipped with a common rail 16 that stores fuel supplied from a fuel supply pump 15 at high pressure. The common rail 16 is equipped with a pressure reducing valve 211 that discharges fuel from the common rail 16 to a fuel return pipe 214. The fuel return pipe 214 is led from the pressure reducing valve 211 to a position higher than the pressure reducing valve 211, and then led to a position lower than the pressure reducing valve 211. Therefore, regardless of the mounting angle of the common rail 16 and the connection direction of the fuel return pipe 214, fuel can be stored between the fuel return pipe 214 part higher than the pressure reducing valve 211 and the pressure reducing valve 211, and the pressure reducing valve 211 can be ensured to be immersed in fuel, and abnormal wear of the sliding part of the pressure reducing valve 211 can be prevented. This relaxes the mounting conditions of the common rail 16 and improves the design freedom of the engine 1.

In the above embodiment, the connection portion (fuel return pipe connection portion 212 and fuel return pipe connection member 213) of the fuel return pipe 214 in the common rail 16 protrudes substantially horizontally from the outer peripheral surface of the common rail 16, but the protruding direction of the connection portion is not limited to this. For example, as shown in FIG. 14, the connection portion 212 and the connection member 213 may protrude diagonally downward to the right from the outer peripheral surface of the common rail 16. In this embodiment, the fuel return pipe 214 extends diagonally downward from the common rail 16. In this embodiment, the fuel return pipe 214 is also led from the pressure reducing valve 211 to a position higher than the pressure reducing valve 211, and then led to a position lower than the pressure reducing valve 211. As a result, fuel can be stored between the fuel return pipe 214 portion higher than the pressure reducing valve 211 and the pressure reducing valve 211, and the pressure reducing valve 211 can be immersed in fuel. As another modification, the fuel return pipe 214 may be extended diagonally downward from the common rail 16, then led to a position higher than the pressure reducing valve 211, and then led to a position lower than the pressure reducing valve 211.

As shown in Figures 1 to 10, the engine 1 has a common rail 16 disposed below the intake manifold 3 provided in the cylinder head 2, and an EGR device 24 that mixes part of the exhaust gas discharged from the exhaust manifold 4 into fresh air, which is connected to the intake manifold 3. The middle part of the fuel return pipe 214 is attached to the EGR device 24 at a position higher than the pressure reducing valve 211, so there is no need to provide the engine 1 with a dedicated part for supporting the middle part of the fuel return pipe 214, and the manufacturing cost of the engine 1 can be suppressed. In addition, by disposing the common rail 16 below the highly rigid intake manifold 3, the common rail 16 can be disposed compactly and the common rail 16 can be physically protected by preventing foreign objects from coming into contact with the common rail 16 from above.

As shown in Figures 1 to 10, the fuel injection pipe 207 extending from the common rail 16 to the cylinder head 2 passes between the cylinder head 2 and the EGR device 24, so the fuel injection pipe 207 can be protected by the EGR device 24. This prevents the fuel injection pipe 207 from coming into contact with other components or being deformed by falling foreign objects when the engine 1 is transported, and eliminates problems such as fuel leaks caused by damage to the fuel injection pipe 207.

The configuration of each part in the present invention is not limited to the illustrated embodiment, and various modifications are possible without departing from the spirit of the present invention.

1. Engine (engine device)
2 Cylinder head 3 Intake manifold 4 Exhaust manifold 15 Fuel supply pump 16 Common rail 24 EGR device (exhaust gas recirculation device)
207 Fuel injection pipe 211 Pressure reducing valve 214 Common rail surplus fuel return pipe (fuel return pipe)

Claims (6)

Common rail and
a first fuel return pipe connected to the common rail and returning fuel in the injectors to the common rail;
a second fuel return pipe connected to one end of the common rail for returning fuel from the fuel supply pump to the common rail;
Equipped with
An engine apparatus, wherein the first fuel return pipe is located above the common rail and is connected to one end of the common rail. The engine apparatus according to claim 1 , wherein the first fuel return pipe is located so as to overlap with a cylinder head in a side view. An intake manifold is further provided,
3. The engine apparatus according to claim 1, wherein a portion of the common rail is disposed so as to overlap with the intake manifold in a plan view. The engine device according to claim 1, wherein the first fuel return pipe is connected in the vertical direction. The engine device according to claim 1, wherein one end of the common rail is closer to the flywheel housing than the other end of the common rail. 2. The engine apparatus according to claim 1, further comprising a third fuel return pipe connected to one end of the common rail for returning fuel in the common rail to a fuel tank.