Engine equipment

Abstract

This provides an engine system that offers greater flexibility in the installation of common rails. [Solution] The engine unit 1 comprises a cylinder head 2, a fuel filter 202, and a common rail 16. The fuel filter 202 is attached to the cylinder head 2 via a bracket. In a side view, the horizontal position of the fuel filter 202 overlaps with the horizontal position of the common rail 16.

Description

Technical Field

[0001] The present invention relates to an engine device provided with a common rail.

Background Art

[0002] In recent years, in diesel engines, due to the need to meet exhaust gas regulations and the increasing demand for low fuel consumption, resulting in higher injection pressures, common rails have come to be used (see, for example, Patent Documents 1 and 2). The common rail stores the fuel supplied from the fuel tank at high pressure. The pressure in the common rail is adjusted by a pressure reducing valve attached to the common rail. The 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.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a common rail, fuel is used for lubricating the sliding part of the pressure reducing valve. Conventionally, in order to immerse the sliding part of the pressure reducing valve in fuel, the mounting angle of the common rail on the engine device (the protruding direction of the fuel return pipe connection part) is ensured within the range of 45 degrees to 90 degrees upward from the horizontal. Also, when the mounting angle is within the range of 0 degrees to 45 degrees, the fuel return pipe is attached upward to the fuel return pipe connection part. Thus, there is a problem that there are restrictions on the connection direction of the fuel return pipe to the common rail and restrictions on the mounting conditions of the common rail.

[0005] The present invention aims to provide an engine device that addresses the above-mentioned current situation and incorporates improvements, which is its technical objective. [Means for solving the problem]

[0006] 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, wherein a fuel return pipe that returns the 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 is connected to the fuel supply pump which is located below the common rail.

[0007] In the engine device of the present invention, the intake manifold may be provided on the cylinder head, and the fuel return pipe may be positioned below the intake manifold.

[0008] Furthermore, an exhaust gas recirculation device that mixes a portion of the exhaust gas discharged from the exhaust manifold with 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.

[0009] In the engine device of the present invention, a fuel pipe may be connected to the side of the common rail opposite to the side to which the fuel return pipe is connected, and the fuel pipe may be connected to the fuel supply pump.

[0010] Furthermore, an oil cooler may be positioned below the intake manifold, and the fuel return pipe may be positioned in front of the oil cooler. [Effects of the Invention]

[0011] The engine device of the present invention relaxes the mounting conditions for common rails and improves the design flexibility of the engine device. [Brief explanation of the drawing]

[0012] [Figure 1] It is a schematic front view of an embodiment of an engine device. [Figure 2] It is a schematic rear view of the embodiment. [Figure 3] It is a schematic left side view of the embodiment. [Figure 4] It is a schematic right side view of the embodiment. [Figure 5] It is a schematic plan view of the embodiment. [Figure 6] It is an explanatory diagram of the fuel system of the embodiment. [Figure 7] It is a schematic front view showing an enlarged view of the periphery of the common rail of the embodiment. [Figure 8] It is a schematic left side view showing an enlarged view of the periphery of the common rail. [Figure 9] It is a schematic plan view showing an enlarged view of the periphery of the common rail. [Figure 10] It is a schematic rear view of the embodiment at the A - A position in FIG. 9. [Figure 11] It is a schematic front view showing an enlarged view of the periphery of the right front corner portion of the embodiment. [Figure 12] It is a schematic plan view showing an enlarged view of the periphery of the right front corner portion of the embodiment. [Figure 13] It is a schematic perspective view showing an enlarged view of the periphery of the right front corner portion of the embodiment. [Figure 14] It is a schematic rear view of another embodiment.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments embodying the present invention will be described based on the drawings. First, referring to FIGS. 1 to 5, the overall structure of an engine 1 as an example of an engine device will be described. In this embodiment, the engine 1 is composed of a diesel engine. In the following description, both side portions parallel to the crankshaft 5 (side portions on both sides sandwiching the crankshaft 5) are referred to as left and right, the side where the flywheel housing 7 is installed is referred to as the front side, and the side where the cooling fan 9 is installed is referred to as the rear side. These are conveniently used as the reference for the positional relationship of the four directions and up and down in the engine 1.

[0014] As shown in FIGS. 1 to 5, an intake manifold 3 is disposed on one side parallel to the crankshaft 5 in the engine 1, and an exhaust manifold 4 is disposed on the other side. In the embodiment, the intake manifold 3 is integrally formed with the cylinder head 2 on the right side surface of the cylinder head 2. The exhaust manifold 4 is installed on the left side surface of the cylinder head 2. The cylinder head 2 is mounted on a cylinder block 6 having a built-in crankshaft 5 and a piston (not shown).

[0015] The front and rear end sides of the crankshaft 5 protrude from the front and rear side surfaces of the cylinder block 6. A flywheel housing 7 is fixed to one side portion (the front side surface side of the cylinder block 6 in the embodiment) intersecting the crankshaft 5 in the engine 1. A flywheel 8 is disposed in 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 power of the engine 1 is configured to be taken out to the operating portion of a working machine (for example, a hydraulic excavator or a forklift) via the flywheel 8. A cooling fan 9 is provided on the other side portion (the rear side surface side of the cylinder block 6 in the embodiment) intersecting the crankshaft 5 in the engine 1. The rotational force is configured to be transmitted from the rear end side of the crankshaft 5 to the cooling fan 9 via a belt 10.

[0016] An oil pan 11 is disposed on the lower surface of the cylinder block 6. Lubricating oil is stored in the oil pan 11. The lubricating oil in the oil pan 11 is sucked by a lubricating oil pump (not shown) disposed on the right side surface side of the cylinder block 6 at the connection portion of the cylinder block 6 with the flywheel housing 7, and is supplied to each lubricating portion of the engine 1 via an oil cooler 13 and an oil filter 14 disposed on the right side surface of the cylinder block 6. The lubricating oil supplied to each lubricating portion is then returned to the oil pan 11. The lubricating oil pump is configured to be driven by the rotation of the crankshaft 5.

[0017] As shown in Figure 4, a fuel supply pump 15 is mounted on the right side of the engine 1 at the connection point between the cylinder block 6 and the flywheel housing 7 to supply fuel. The fuel supply pump 15 is located below the EGR (exhaust gas recirculation) device 24. A common rail 16 is positioned 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. On the upper surface of the cylinder head 2, which is covered by the cylinder head cover 18, there are four injectors 17 (see Figure 6) each with an electromagnetically controlled fuel injection valve.

[0018] Each injector 17 is connected to a fuel tank 201 (see Figure 6) mounted on the work vehicle via a fuel supply pump 15 and a roughly cylindrical common rail 16. Fuel from 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 valve 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.

[0019] As shown in Figures 2 and 5, a blow-by gas recirculation device 19 is installed on the upper surface of the cylinder head cover 18, which covers the intake valve and exhaust valve (not shown) etc. located on the upper surface of the cylinder head 2, and takes in blow-by gas that has leaked from the combustion chamber of the engine 1 to the upper surface of the cylinder head 2. A blow-by gas outlet of the blow-by gas recirculation device 19 is connected to the intake section of the two-stage supercharger 30 via a recirculation hose 68. The blow-by gas from which lubricating oil components have been removed in the blow-by gas recirculation device 19 is returned to the intake manifold 3 via the two-stage supercharger 30, etc.

[0020] As shown in Figure 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 located below the exhaust manifold 4. The engine starter 20 is attached to the left side of the rear side of the flywheel housing 7, at a position below the connection between the cylinder block 6 and the flywheel housing 7.

[0021] As shown in Figure 2, a coolant pump 21 for coolant lubrication is located on the left side of the rear side of the cylinder block 6. An alternator 12, which generates electricity using the power of the engine 1, is located to the left of the coolant pump 21. Rotational power is transmitted from the front end of the crankshaft 5 to the cooling fan 9, alternator 12, and coolant pump 21 via a belt 10. Coolant in a radiator (not shown) mounted on the work vehicle is supplied to the coolant pump 21 by the drive of the coolant pump 21. Coolant is then supplied to the cylinder head 2 and cylinder block 6, cooling the engine 1.

[0022] As shown in Figure 3, the coolant pump 21 is positioned at a lower height than the exhaust manifold 4, and the coolant inlet pipe 22, which communicates with the coolant outlet of the radiator, is fixed to the left side of the cylinder block 6 at approximately the same height as the coolant pump 21. On the other hand, the coolant outlet pipe 23, which communicates with the coolant inlet of the radiator, is fixed to the rear right portion of the upper surface of the cylinder head 2, as shown in Figures 2 and 5. The cylinder head 2 has a coolant drain section 35 at its right rear corner, and the coolant outlet pipe 23 is installed on the upper surface of the coolant drain section 35.

[0023] As shown in Figures 4 and 5, the EGR device 24 is located to the right of the cylinder head 2. The EGR device 24 includes a collector 25 which serves as a relay line that mixes the recirculated exhaust gas of the engine 1 (EGR gas from the exhaust manifold 4) with fresh air (outside air from the air cleaner) and supplies it to the intake manifold 3, an intake throttle member 26 which connects the collector 25 to the air cleaner, a recirculated exhaust gas pipe 28 which is part of the return line that connects to the exhaust manifold 4 via an EGR cooler 27, and an EGR valve member 29 which connects the collector 25 to the recirculated exhaust gas pipe 28.

[0024] In this embodiment, the collector 25 of the EGR device 24 is connected to the right side of the intake manifold 3, which is integrally molded with the cylinder head 2 and constitutes 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, which is provided on the right side of the cylinder head 2. In addition, the EGR gas inlet of the recirculating exhaust gas piping 28 is connected to the EGR gas outlet of the EGR gas passage provided inside the cylinder head 2, at the front part of the right side of the cylinder head 2. The EGR device 24 is fixed to the cylinder head 2 by attaching the collector 25 to the intake manifold 3 and the recirculating exhaust gas piping 28 to the cylinder head 2.

[0025] In the EGR device 24, the intake manifold 3 and the intake throttle member 26 for introducing fresh air are connected via a 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 piping 28. The collector 25 is formed in a roughly cylindrical shape along its longitudinal length. The intake throttle member 26 is bolted to the intake side (front side in the longitudinal direction) of the collector 25. The intake discharge side of the collector 25 is bolted to the inlet side of the intake manifold 3. The EGR valve member 29 adjusts the amount of EGR gas supplied to the collector 25 by adjusting the opening degree of the EGR valve located inside it.

[0026] Fresh air is supplied into the collector 25, and EGR gas (a portion of the exhaust gas discharged from the exhaust manifold 4) is also 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, a portion of the exhaust gas discharged from the engine 1 to the exhaust manifold 4 is returned to the engine 1 from the intake manifold 3, thereby lowering the maximum combustion temperature during high-load operation and reducing the amount of NOx (nitrogen oxides) emitted from the engine 1.

[0027] As shown in Figures 1 and 3-5, the EGR cooler 27 is fixed to the front side surface of the cylinder head 2. Cooling water and EGR gas flowing inside the cylinder head 2 flow into and out of the EGR cooler 27, and the EGR gas is cooled within the EGR cooler 27. A pair of left and right EGR cooler connecting parts 33 and 34 that connect the EGR cooler 27 are provided protruding from the front side surface of the cylinder head 2. The left EGR cooler connecting part 33 protrudes forward from the left front corner of the cylinder head 2. The right EGR cooler connecting part 34 is spaced apart from the left EGR cooler connecting part 33 and protrudes 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 and 34. In other words, the EGR cooler 27 is positioned above the flywheel housing 7 and in front of the cylinder head 2, such that the rear side of the EGR cooler 27 and the front side of the cylinder head 2 are spaced apart.

[0028] As shown in Figures 1-3 and 5, a two-stage supercharger 30 is located on the left side of the cylinder head 2. The two-stage supercharger 30 comprises a high-pressure stage supercharger 51 and a low-pressure stage supercharger 52. The high-pressure stage supercharger 51 has a high-pressure stage turbine case 53 that houses a turbine wheel (not shown) and a high-pressure stage compressor case 54 that houses a blower wheel (not shown). The low-pressure stage supercharger 52 has a low-pressure stage turbine case 55 that houses a turbine wheel (not shown) and a low-pressure stage compressor case 56 that houses a blower wheel (not shown).

[0029] 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 high-pressure exhaust gas piping 59, and the exhaust connecting pipe 119 is connected to the low-pressure stage turbine case 55. The high-pressure exhaust gas piping 59 is made of flexible piping. In this embodiment, a portion of the high-pressure exhaust gas piping 59 is formed in a bellows shape.

[0030] A tailpipe (not shown) is connected to the exhaust connecting pipe 119 via an exhaust gas purification device (not shown), etc. The exhaust gas discharged from each cylinder of the engine 1 to the exhaust manifold 4 is released to the outside through the tailpipe after passing through the two-stage supercharger 30 and the exhaust gas purification device, etc.

[0031] In the intake passage of the two-stage supercharger 30, the low-pressure stage compressor case 56 is connected to the air cleaner via the intake pipe 62, the high-pressure stage compressor case 54 is connected to the low-pressure stage compressor case 56 via the low-pressure fresh air passage pipe 65, and the intake throttle member 26 of the EGR device 24 is connected to the high-pressure stage compressor case 54 via the intercooler (not shown). The fresh air (outside air) drawn into the air cleaner is dust-removed and purified by the air cleaner, and then sent to the intake manifold 3 via the two-stage supercharger 30, intercooler, intake throttle member 26, collector 25, etc., and then supplied to each cylinder of the engine 1.

[0032] Next, the common rail system 200 and the fuel system structure of engine 1 will be described with reference to Figure 6. A fuel tank 201 is connected to each of the four injectors 17 provided in 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 roughly cylindrical common rail 16.

[0033] A fuel tank 201 is connected to the suction 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, a 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 end of the common rail 16 in the longitudinal direction. The end of the fuel supply high-pressure pipe 204 is connected to the high-pressure pipe connection part 205 by screwing in a high-pressure pipe connector nut 206. Fuel in the fuel tank 201 is drawn into the fuel supply pump 15 via the fuel filter 202 and the fuel supply low-pressure pipe 203, and then pumped from the fuel supply pump 15 to the common rail 16 via the fuel supply high-pressure pipe 204.

[0034] Furthermore, four injectors 17 for each of the four cylinders are connected to the common rail 16 via four fuel injection pipes 207. Four fuel injection pipe connection sections 208 for each of 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 in injection pipe connector nuts 209.

[0035] A pressure reducing valve 211 is attached to the end face of the common rail 16 opposite to the one end mentioned above. The pressure reducing valve 211 discharges fuel from the common rail 16 to the common rail surplus fuel return pipe 214 via a fuel return pipe connection member 213 from a fuel return pipe connection portion 212 provided on the other end side of the outer circumferential surface of the common rail 16. 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.

[0036] A return pipe joint member 216 for returning excess fuel is provided on the end face of one end of the common rail 16. Fuel discharged from the common rail 16 by the operation of the pressure reducing valve 211 and excess fuel from the fuel supply pump 15 are sent to the return pipe joint member 216 via the return pipe joint member 215 and the pump excess fuel return pipe 217. In addition, excess fuel from each injector 17 is sent to the return pipe joint member 216 via the injector excess fuel return pipe 218. The excess fuel that is merged at the return pipe joint member 216 is recovered into the fuel tank 201 via the fuel return pipe 219. Although not shown in Figure 6, the middle part of the fuel return pipe 219 is connected to a return pipe connection part 220 (see Figure 12) provided on the upper part of the fuel filter 202.

[0037] A fuel pressure sensor 601 is attached to the common rail 16 to detect the fuel pressure within 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 and, consequently, the fuel discharge amount of the fuel supply pump 15 are adjusted, fuel from the fuel tank 201 is pumped to the common rail 16 by the fuel supply pump 15, and high-pressure fuel is stored in the common rail 16.

[0038] Under the control of the engine controller 600, each fuel injection valve 17a is opened and closed, thereby injecting high-pressure fuel from the common rail 16 into each cylinder of the engine 1 from each injector 17. In other words, by electronically controlling each fuel injection valve 17a, the injection pressure, injection timing, and injection duration (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. In addition, although not shown in the figures, the engine controller 600 is also electrically connected to other devices, such as various sensors provided in the engine 1.

[0039] Next, the layout around 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 axis 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.

[0040] A high-pressure pipe connection section 205, four fuel injection pipe connection sections 208, and a fuel return pipe connection section 212 are provided protruding from the right side of the outer circumferential surface of the common rail 16. These connection sections 205, 208, and 212 protrude toward the right side and, in this embodiment, protrude substantially horizontally. That is, in this embodiment, the common rail 16 is mounted to the engine 1 at a mounting angle of 0 degrees. The high-pressure pipe connection section 205 is located towards the front of the common rail 16. The fuel return pipe connection section 212 is located towards the rear of the common rail 16. The four fuel injection pipe connection sections 208 are arranged at equal intervals between the fuel return pipe connection section 212 and the fuel return pipe connection section 212.

[0041] As shown in Figure 10, one end of the common rail surplus fuel return pipe 214 (the upstream end of the fuel flow) is connected to the fuel return pipe connection section 212 via a fuel return pipe connecting member 213. The fuel return pipe 214 is guided horizontally to the right from the fuel return pipe connection section 212, then curves diagonally upward to the right, and is guided to a position higher than the pressure reducing valve 211. In this embodiment, the fuel return pipe 214 is guided to the vicinity of the front lower portion 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 portion 25a of the collector 25 by a pipe mounting member 221. Furthermore, the fuel return pipe 214 curves diagonally downward from the vicinity of the front lower portion 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 connecting member 213 is attached to the fuel return pipe connection section 212 so as to protrude substantially horizontally to the right from the fuel return pipe connection section 212.

[0042] In this embodiment, the common rail excess fuel return pipe 214 is led from the pressure reducing valve 211 to a position higher than the pressure reducing valve 211, and then to a position lower than the pressure reducing valve 211. Therefore, regardless of the mounting angle of the common rail 16 and the direction in which the fuel return pipe 214 is connected to the common rail 16, fuel can be stored between the portion of the fuel return pipe 214 at a position 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 design flexibility of the engine 1 is improved.

[0043] Furthermore, since the intermediate portion of the fuel return pipe 214 is attached to the collector 25 of the EGR device 24 at a higher position than the pressure reducing valve 211, there is no need to provide a dedicated part in the engine 1 to support the intermediate portion of the fuel return pipe 214, thereby suppressing an increase in the manufacturing cost of the engine 1. In addition, by positioning the common rail 16 below the highly rigid intake manifold 3, the common rail 16 can be compactly positioned, and foreign matter contact with the common rail 16 from above can be prevented, thus physically protecting the common rail 16.

[0044] As shown in Figures 7 to 10, the front end of the common rail 16 is positioned on the flywheel housing 7. A return pipe joint member 216 for returning excess fuel, which merges multiple fuel return paths, is attached to the front end of the common rail 16. The return pipe joint member 216 is positioned on the flywheel housing 7. By positioning one end (front end) of the common rail 16 above the flywheel housing 7, the area occupied by the common rail 16 on the right side of the cylinder block 6 can be reduced compared to a configuration where the entire common rail 16 is positioned 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 positioned behind the common rail 16, and the oil cooler 13 is positioned close to the intake manifold 3 and the EGR device 24, enabling a compact arrangement of these components.

[0045] As shown in Figure 7, the return pipe joint member 216 includes 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 Figure 12) is connected. Inside the return pipe joint member 216, there is an internal flow path (not shown) connecting the connection parts 217a, 218a, and 219a, and a fuel pressure regulating valve (not shown) positioned between the internal flow path and the internal space of the common rail 16.

[0046] Furthermore, in the cylinder head 2, an excess fuel outlet 218b (see Figure 7) is provided near the corner where the right side and front side of the cylinder head 2 intersect. The excess fuel outlet 218b is located 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 injectors 17 (see Figure 6) located inside 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 portion 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 Figure 6) via an excess fuel passage (not shown) formed inside the side wall of the cylinder head 2.

[0047] As shown in Figures 7 to 10, the four fuel injectors 207, which are attached to the four fuel injector connections 208 by injector connector nuts 209, are each led horizontally to the right from the fuel injector connections 208, below the EGR device 24. Then, each fuel injector 207 curves toward the cylinder block 6 below the EGR device 24, and then curves upward, passing between the cylinder head 2 and the EGR device 24, and is led to the right side of the cylinder head cover 18. As shown in Figures 8, 9 and 13, the middle sections of the four fuel injectors 207 are attached to the cylinder head 2 by a pair of front and rear fuel injector fasteners 614, 614 attached to the right side of the cylinder head 2.

[0048] Two fuel injectors 207 are fixed to each fuel injector fixing device 614, 614. The intermediate sections of the two fuel injectors 207 on the front side of the engine 1 are fixed by the front fuel injector fixing device 614 to the end face of a projection 615 that protrudes to the right on the right side of the cylinder head 2 in front of the intake manifold 3. The intermediate sections of the two fuel injectors 207 on the rear side of the engine 1 are fixed by the rear fuel injector fixing device 614 to the right side of the intake manifold 3, which is integrally molded with the right side of the cylinder head 2.

[0049] Each fuel injection pipe 207 passes between the cylinder head 2 and the EGR device 24, so the EGR device 24 can protect the fuel injection pipes 207. This prevents the fuel injection pipes 207 from coming into contact with other components or being deformed by foreign objects falling during transport of the engine 1, and prevents problems such as fuel leaks caused by damage to the fuel injection pipes 207.

[0050] Furthermore, by fixing the intermediate portion of the fuel injection pipe 207 to the cylinder head 2, vibration of the fuel injection pipe 207 is reduced, preventing damage to the fuel injection pipe 207 caused by vibration. In addition, in this embodiment, the intermediate 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 that 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 even more firmly.

[0051] As shown in Figures 7 to 10, one end of the fuel supply high-pressure pipe 204, which connects to the common rail 16, is connected to the upper right side of the fuel supply pump 15. The fuel supply high-pressure pipe 204 is led from the upper right side of the fuel supply pump 15 toward the right, then curves diagonally upward and forward, and further curves toward the upper front portion of the right side of the cylinder block 6. The fuel supply high-pressure pipe 204 then passes below the EGR device 24 and is led to the high-pressure pipe connection part 205 of the common rail 16. The other end of the fuel supply high-pressure pipe 204 is connected to the high-pressure pipe connection part 205 by a high-pressure pipe connect nut 206.

[0052] The fuel supply high-pressure pipe 204, the four fuel injection pipes 207, and the common rail excess 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, fuel injection pipes 207, and fuel return pipe 214, improving the reliability of engine 1.

[0053] As shown in Figures 7 to 10, the high-pressure pipe connection 205, the four fuel injection pipe connections 208, and the fuel return pipe connection 212 are provided projecting substantially horizontally from the right side of the outer circumferential surface of the common rail 16 toward the right. Furthermore, there are no connection points for connecting piping on the upper and left sides of the outer circumferential surface of the common rail 16. Therefore, the common rail 16 can be positioned close to the lower surface of the intake manifold 3 and the right side of the cylinder block 6, the intake manifold 3 can protect the common rail 16, and the common rail 16 can be compactly positioned in the engine 1.

[0054] As shown in Figures 5 and 11-13, a fuel filter 202 is provided in the upper right front portion of the engine 1. The fuel filter 202 is positioned above the right-leaning 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 positioning the fuel filter 202 in the empty space above the flywheel housing 7, the fuel filter 202 can be compactly installed in the engine 1, thereby achieving a more compact engine 1.

[0055] The upper left edge of the fuel filter 202 is fixed to the upper right front portion of the filter mounting bracket 231 with two bolts 232 and 233. The filter mounting bracket 231 is fixed to the right EGR cooler connection portion 34 with bolts 234 and 235 that are attached to bolt mounting holes 234a and 235a (see Figure 9) on the upper surface of the right EGR cooler connection portion 34, and with bolt 2346 that is attached to bolt mounting hole 236a (see Figure 7) on the front side of the right edge portion 34a of the right EGR cooler connection portion 34. By fixing the filter mounting bracket 231 to the upper and front side of the right EGR cooler connection portion 34 of the cylinder block 6, the filter mounting bracket 231 can be firmly fixed to the cylinder block 6, and consequently, the fuel filter 202 can be firmly fixed to the cylinder block 6.

[0056] As shown in Figures 11 to 13, the return pipe joint member 215, located on the right side of the fuel supply pump 15, is connected to the connection portion 217a of the return pipe joint 216, which is attached to the front end of the common rail 16, via the pump surplus fuel return pipe 217. The connection portion 218a of the return pipe joint 216 is connected to the surplus fuel outlet 218b (see Figure 7), located at the front right corner of the cylinder head 2, via the injector surplus fuel return pipe 218c, which extends vertically. The connection portion 219a of the return pipe joint 216 is connected to the fuel tank 201 (see Figure 6) via the upstream fuel return pipe 219b, the return pipe connecting portion 220 located at the top of the fuel filter 202, and the downstream fuel return pipe 219c. Additionally, a fuel supply pipe 210, which connects to the fuel tank 201, and a low-pressure fuel supply pipe 203, which connects to the lower right side of the fuel supply pump 15, are also connected to the top of the fuel filter 202.

[0057] In this embodiment of engine 1, the fuel supply pump 15, common rail 16, and fuel filter 202 are arranged in one corner of the engine 1 (in this case, the front right 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 section 216 for returning surplus fuel, which is 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 their piping length shorter and simpler. Furthermore, by concentrating the fuel supply pump 15, common rail 16, and fuel filter 202 in one corner of the engine 1, the piping length of the connecting pipes (fuel supply low-pressure pipe 203, fuel supply high-pressure pipe 204, and common rail surplus fuel return pipe 214) can be made shorter and simpler.

[0058] As shown in Figure 10, the engine 1 is an engine system 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 the fuel in 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 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 portion of the fuel return pipe 214 that is higher than the pressure reducing valve 211 and the pressure reducing valve 211, ensuring that the pressure reducing valve 211 is immersed in fuel and preventing abnormal wear of the sliding part of the pressure reducing valve 211. This relaxes the mounting conditions of the common rail 16 and improves the design flexibility of the engine 1.

[0059] In the above embodiment, the connection portion of the fuel return pipe 214 in the common rail 16 (fuel return pipe connection portion 212 and fuel return pipe connection member 213) protrudes substantially horizontally from the outer circumferential surface of the common rail 16, but the direction of protrusion of the connection portion is not limited to this. For example, as shown in Figure 14, the connection portion 212 and the connection member 213 may protrude diagonally downward to the right from the outer circumferential 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 as well, 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 to a position lower than the pressure reducing valve 211. This allows fuel to be stored between the portion of the fuel return pipe 214 at a position higher than the pressure reducing valve 211 and the pressure reducing valve 211, ensuring that the pressure reducing valve 211 is 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.

[0060] Furthermore, as shown in Figures 1 to 10, the engine 1 has a common rail 16 positioned below the intake manifold 3 located on the cylinder head 2, and an EGR device 24 that mixes a portion of the exhaust gas discharged from the exhaust manifold 4 with fresh air is connected to the intake manifold 3. The middle section of the fuel return pipe 214 is attached to the EGR device 24 at a higher position than the pressure reducing valve 211, so there is no need to provide a special part in the engine 1 to support the middle section of the fuel return pipe 214, thereby suppressing an increase in the manufacturing cost of the engine 1. In addition, by positioning the common rail 16 below the highly rigid intake manifold 3, the common rail 16 can be compactly positioned, and the common rail 16 can be physically protected by preventing foreign matter from contacting it from above.

[0061] Furthermore, 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 foreign objects falling during transport of the engine 1, and eliminates problems such as fuel leakage caused by damage to the fuel injection pipe 207.

[0062] Furthermore, 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. [Explanation of symbols]

[0063] 1. Engine (engine device) 2 Cylinder heads 3. Intake Manifold 4 Exhaust Manifold 15 Fuel supply pump 16 Common Rail 24. EGR system (Exhaust gas recirculation system) 207 Fuel injection pipe 211 Pressure Reducing Valve 214 Common rail surplus fuel return pipe (fuel return pipe)

Claims

1. Equipped with a cylinder head, fuel filter and common rail, An engine system in which, in a side view, the horizontal position of the fuel filter overlaps with the horizontal position of the common rail.

2. The engine device according to claim 1, wherein the fuel filter is attached to the cylinder head via a bracket.

3. The engine device according to claim 2, wherein the bracket is fixed to the connecting portion of the EGR cooler.

4. The engine device according to claim 1, wherein the fuel filter is located above the flywheel housing.

5. The engine device according to claim 1, wherein the fuel filter overlaps with the flywheel housing in a plan view.

6. The engine device according to claim 1, wherein the fuel filter is adjacent to the EGR cooler.

7. The engine device according to claim 1, wherein the common rail is positioned below the fuel filter.

Images