Engine equipment

Abstract

To reduce an area occupied by an arrangement region of a common rail in one side portion of an engine system.SOLUTION: In an engine (engine system) including a common rail 16, a plurality of surplus fuel return pipes (pump surplus fuel return pipe 131, injector surplus fuel return pipe 132) is connected to an end part of the common rail 16.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to an engine device, and more particularly to an engine device having a common rail attached to one side along the crank axis of a cylinder block that rotatably supports a crankshaft. [Background technology]

[0002] In recent years, common rails have come to be used in diesel engines due to increased injection pressures resulting from increased demands for low fuel consumption (see, for example, Patent Document 1). Common rails are often attached to the cylinder block and store fuel supplied from a fuel tank at high pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-297989 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION An object of the present invention is to reduce the area occupied by the common rail on one side of an engine system. [Means for solving the problem]

[0005] The engine device of the present invention is an engine device equipped with a common rail and a fuel supply pump, in which a flywheel housing that accommodates a flywheel that rotates integrally with the crankshaft is arranged on one of the front and rear sides of the engine device, one end of the common rail is arranged above the flywheel housing, and the end of the common rail and the fuel supply pump are connected to an excess fuel return pipe. [Effects of the Invention]

[0006] According to the present invention, the area occupied by the common rail on one side of the engine device can be reduced. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a perspective view of the engine as seen obliquely from the front. [Figure 8] FIG. 2 is a perspective view of the engine as seen obliquely from the rear. [Figure 9] FIG. 2 is a plan view showing the cylinder block and the flywheel housing. [Figure 10] FIG. 2 is a left side view showing the cylinder block and the flywheel housing. [Figure 11] FIG. 2 is a right side view showing the cylinder block and the flywheel housing. [Figure 12] FIG. [Figure 13] FIG. 10 is a cross-sectional view taken along the line AA in FIG. 9. [Figure 14] FIG. 10 is a cross-sectional view taken along the line BB in FIG. 9. [Figure 15] FIG. 2 is a perspective view showing the inside of a flywheel housing. [Figure 16] FIG. 2 is a perspective view showing the mounting position of a fuel supply pump. [Figure 17] FIG. 2 is an explanatory diagram of a fuel system of the engine. [Figure 18] FIG. [Figure 19] FIG. [Figure 20]FIG. [Figure 21] FIG. 2 is a plan view showing the periphery of the common rail. [Figure 22] FIG. 2 is a perspective view showing a fuel injection pipe. [Figure 23] FIG. 4 is a bottom view showing the common rail connector with the oil pan and cylinder block partially cut away. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the overall structure of an engine (engine device) 1, which is a diesel engine, will be described with reference to Figures 1 to 8. In the following description, both sides parallel to the crankshaft 5 (both sides sandwiching the crankshaft 5) will be referred to as the left and right, the side where the flywheel housing 7 is installed will be referred to as the front side, and the side where the 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 relationship between the four sides and the top and bottom of the engine 1.

[0009] As shown in Figures 1 to 8, an intake manifold 3 is disposed on one side of an engine 1 parallel to a 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, and the exhaust manifold 4 is disposed on the left side thereof. The cylinder head 2 is mounted on a cylinder block 6 that houses the crankshaft 5 and pistons (not shown). The cylinder block 6 supports the crankshaft 5 so that it can rotate freely.

[0010] 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 fixedly mounted on one side of the engine 1 that intersects with the crankshaft 5 (on the front side of the cylinder block 6 in this embodiment). A flywheel 8 is disposed within the flywheel housing 7. The flywheel 8 is journaled on the front end side of the crankshaft 5 and is configured to rotate integrally with the crankshaft 5. Power from the engine 1 is extracted via the flywheel 8 to a working unit of a work machine (for example, a hydraulic excavator or a forklift). A cooling fan 9 is mounted on the other side of the engine 1 that intersects with the crankshaft 5 (on the rear side of the cylinder block 6 in this embodiment). Rotational force is transmitted from the rear end of the crankshaft 5 to the cooling fan 9 via a V-belt 10.

[0011] 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 by an oil pump 12 (see FIG. 11) located on the right side of the cylinder block 6, at 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 located 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 oil pump 12 is configured to be driven by the rotation of the crankshaft 5.

[0012] A fuel supply pump 15 for supplying fuel is attached to the connecting portion of the cylinder block 6 with the flywheel housing 7, and is disposed below the EGR device 24. A common rail 16 is fixed to the side of the cylinder block 6 below the intake manifold 3 of the cylinder head 2, and is disposed above the fuel supply pump 15. On the top surface of the cylinder head 2 covered with a head cover 18, injectors 17 (see Figure 17) for each of the four cylinders are provided, each having an electromagnetically controlled fuel injection valve.

[0013] Each injector 17 is connected to a fuel tank 118 (see FIG. 17) mounted on the work vehicle via a fuel supply pump 15 and a cylindrical common rail 16. Fuel from the fuel tank is pumped from the fuel supply pump 15 to the common rail 16, and the high-pressure fuel is stored in the common rail 16. By controlling the opening and closing of a fuel injection valve 119 (see FIG. 17) 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.

[0014] A blow-by gas reduction device 19 that takes in blow-by gas that leaks from the combustion chamber of the engine 1 to the upper side of the cylinder head 2 is provided on the upper surface of a head cover 18 that covers the intake valves and exhaust valves (not shown) provided on the upper surface of the cylinder head 2. A blow-by gas outlet of the blow-by gas reduction device 19 is connected to the intake part of the two-stage turbocharger 30 via a reduction hose 68. The blow-by gas from which lubricating oil components have been removed in the blow-by gas reduction device 19 is reduced to the intake manifold 3 via the two-stage turbocharger 30.

[0015] A starter 20 for starting the engine is attached to the flywheel housing 7, and the starter 20 is disposed below the exhaust manifold 4. The starter 20 is attached to the flywheel housing 7 at a position below the joint between the cylinder block 6 and the flywheel housing 7.

[0016] A cooling water pump 21 for circulating cooling water is disposed below the cooling fan 9 in a position near the left rear surface of the cylinder block 6. The cooling water pump 21 is driven together with the cooling fan 9 via a cooling fan drive V-belt 10 by the rotation of the crankshaft 5. Cooling water in a radiator (not shown) mounted on the work vehicle is supplied to the cooling water pump 21 by the drive of the cooling water pump 21. The cooling water is then supplied to the cylinder head 2 and the cylinder block 6, cooling the engine 1.

[0017] A cooling water inlet pipe 22, which is disposed below the exhaust manifold 4 and communicates with the cooling water outlet of the radiator, is fixed to the left side surface of the cylinder block 6 at the same height as the cooling water pump 21. Meanwhile, a cooling water outlet pipe 23, which communicates with the cooling water inlet of the radiator, is fixed to the rear part of the cylinder head 2. The cylinder head 2 has a cooling water drainage section 35 that protrudes rearward from the intake manifold 3, and the cooling water outlet pipe 23 is installed on the upper surface of the cooling water drainage section 35.

[0018] The inlet side of the intake manifold 3 is connected to an air cleaner (not shown) via a collector 25 of an EGR device 24 (exhaust gas recirculation device) described later. Fresh air (external air) drawn into the air cleaner is cleaned and purified by the air cleaner, then sent to the intake manifold 3 via the collector 25 and supplied to each cylinder of the engine 1. 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 forms the right side of the cylinder head 2. That is, the outlet opening of the collector 25 of the EGR device 24 is connected to the inlet opening of the intake manifold 3 provided on the right side of the cylinder head 2. In this embodiment, the collector 25 of the EGR device 24 is connected to the air cleaner via an intercooler (not shown) and a two-stage turbocharger 30, as described later.

[0019] 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 the mixture 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 reflux 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.

[0020] The EGR device 24 is disposed on the right side of the intake manifold 3 in the cylinder head 2. That is, the EGR device 24 is fixed to the right side surface of the cylinder head 2 and is connected to the intake manifold 3 inside the cylinder head 2. The EGR device 24 has a collector 25 connected to the intake manifold 3 on the right side surface of the cylinder head 2, and an EGR gas inlet of a recirculation exhaust gas pipe 28 connected and fixed to a front portion of the intake manifold 3 on the right side surface of the cylinder head 2. An EGR valve member 29 and an intake throttle member 26 are connected to the front and rear of the collector 25, respectively, and the EGR gas outlet of the recirculation exhaust gas pipe 28 is connected to the rear end of the EGR valve member 29.

[0021] The EGR cooler 27 is fixed to the front side of the cylinder head 2, and the cooling water and EGR gas flowing inside the cylinder head 2 flow in and out of the EGR cooler 27, where the EGR gas is cooled. EGR cooler connection seats 33, 34 that connect the EGR cooler 27 are provided protrudingly on the left and right sides of the front side of the cylinder head 2, and the EGR cooler 27 is connected to the connection seats 33, 34. In other words, the EGR cooler 27 is disposed above the flywheel housing 7 and in front of the cylinder head 2, with the rear end face of the EGR cooler 27 separated from the front side of the cylinder head 2.

[0022] The two-stage turbocharger 30 is disposed to the side (left side in this embodiment) of the exhaust manifold 4. The two-stage turbocharger 30 includes a high-pressure turbocharger 51 and a low-pressure turbocharger 52. The high-pressure turbocharger 51 has a high-pressure turbine 53 incorporating a turbine wheel (not shown) and a high-pressure compressor 54 incorporating a blower wheel (not shown), while the low-pressure turbocharger 52 has a low-pressure turbine 55 incorporating a turbine wheel (not shown) and a low-pressure compressor 56 incorporating a blower wheel (not shown).

[0023] An exhaust gas inlet 57 of the high-pressure turbine 53 is connected to the exhaust manifold 4, an exhaust gas inlet 60 of the low-pressure turbine 55 is connected to an exhaust gas outlet 58 of the high-pressure turbine 53 via a high-pressure exhaust gas pipe 59, and an exhaust gas intake end of an exhaust gas discharge pipe (not shown) is connected to an exhaust gas outlet 61 of the low-pressure turbine 55. Meanwhile, a fresh air intake (fresh air inlet) 63 of the low-pressure compressor 56 is connected to the fresh air supply side (fresh air outlet side) of an air cleaner (not shown) via an air intake pipe 62, a fresh air intake 66 of the high-pressure compressor 54 is connected to a fresh air supply port (fresh air outlet) 64 of the low-pressure compressor 56 via a low-pressure fresh air passage pipe 65, and a fresh air supply port 67 of the high-pressure compressor 54 is connected to the fresh air intake side of an intercooler (not shown) via a high-pressure fresh air passage pipe (not shown).

[0024] The high-pressure turbocharger 51 is connected to an exhaust gas outlet 58 of the exhaust manifold 4 and fixed to the left side of the exhaust manifold 4, while the low-pressure turbocharger 52 is connected to the high-pressure turbocharger 51 via a high-pressure exhaust gas pipe 59 and a low-pressure fresh air passage pipe 65 and fixed above the exhaust manifold 4. That is, the small-diameter high-pressure turbocharger 51 and the exhaust manifold 4 are arranged side by side on the left and right below the large-diameter low-pressure turbocharger 52, so that the two-stage turbocharger 30 is arranged to surround the left side and top of the exhaust manifold 4. That is, the exhaust manifold 4 and the two-stage turbocharger 30 are arranged in a rectangular shape when viewed from behind (when viewed from the front) and are fixed compactly to the left side of the cylinder head 2.

[0025] Next, the configuration of the cylinder block 6 will be described with reference to Figures 9 to 13. The cylinder block 6 has a left housing bracket portion 304 and a right housing bracket portion 305 (protruding portions) formed at the ends of the front side surface 303 of the left and right side surfaces 301 and 302 along the crank axis 300 of the crankshaft 5. The flywheel housing 7 is fixed to the left housing bracket portion 304 with a plurality of bolts. A first left reinforcing rib 306, a second left reinforcing rib 307, a third left reinforcing rib 308, and a fourth left reinforcing rib 309 are formed between the side wall of the left side surface 301 and the left housing bracket portion 304, in that order from the top side (top deck side) to the bottom side (oil pan rail side). A first right reinforcing rib 310 and a second right reinforcing rib 311 are formed between the side wall of the right side surface 302 and the right housing bracket portion 305, in that order from the top side to the bottom side. The housing bracket portions 304 and 305 and the reinforcing ribs 306 to 311 are integrally formed with the cylinder block 6.

[0026] The reinforcing ribs 306-311 each extend along the crankshaft axis 300 and have a generally triangular shape in plan view, with the housing bracket portions 304, 305 being wider. The left reinforcing ribs 307, 308, 309 and the right second reinforcing rib 311 each have linear portions 307a, 308a, 309a, 311a extending from the generally triangular portion toward the rear side surface 312 of the cylinder block 6 (see also Figures 7 and 8). The reinforcing ribs 306, 307, 308 are disposed in the cylinder portion of the cylinder block 6. The reinforcing ribs 309, 310, 311 are disposed in the skirt portion of the cylinder block 6.

[0027] On each of the left and right side surfaces 301 and 302, two mount attachment seats 317 for attaching engine mounts that connect the engine 1 to the vehicle body are provided in a protruding manner in the front-to-rear direction, near the oil pan rail. The left-side fourth reinforcing rib 309 is connected to the two mount attachment seats 317 protruding from the left side surface 301. The right-side second reinforcing rib 311 is connected to the two mount attachment seats 317 protruding from the right side surface 302. As shown in FIG. 17 , a crankcase cover member 326 that covers the periphery of the crankshaft 5 is fixed with bolts to the rear side surface 312 of the cylinder block 6 so that the inside of the crankcase is not exposed to the outside of the engine 1. The oil pan 11 is fastened to the underside of the crankcase cover member 326 with bolts.

[0028] The housing bracket portions 304, 305 and reinforcing ribs 306-311, which are integrally molded with the cylinder block 6, improve the rigidity of the cylinder block 6, particularly the rigidity and strength of the area near the front side surface 303 of the cylinder block 6, thereby reducing vibration and noise of the engine 1. Furthermore, the housing bracket portions 304, 305 and reinforcing ribs 306-311 increase the surface area of ​​the cylinder block 6, thereby improving the cooling efficiency of the cylinder block 6 and, ultimately, the cooling efficiency of the engine 1.

[0029] Furthermore, a cooling water pump mounting portion 319 to which the cooling water pump 21 (see FIG. 2, etc.) is attached, and an inlet pipe mounting seat 320 to which the cooling water inlet pipe 22 (see FIG. 3, etc.) is attached, protrude from a portion of the left side surface 301 of the cylinder block 6 near the rear side surface 312. The cooling water pump mounting portion 319 and the inlet pipe mounting seat 320 are integrally molded with the cylinder block 6. Furthermore, a portion of the inlet pipe mounting seat 320 on the rear side surface 312 side is connected to the cooling water pump mounting portion 319. The cooling water pump mounting portion 319 and the inlet pipe mounting seat 320 protrude in a direction away from the crankshaft 5, thereby improving the rigidity, strength, and cooling efficiency of the cylinder block 6.

[0030] A camshaft case 314 (see FIG. 13) that houses a camshaft 313 is formed inside the cylinder block 6. Although details are omitted, a crank gear 331 fixed to the crankshaft 5 and a cam gear 332 fixed to the camshaft 313 are arranged on the front side surface 303 of the cylinder block 6, and the cam gear 332 and the camshaft 313 are rotated in conjunction with the crank gear 331 to drive a valve train (not shown) associated with the camshaft 313, thereby opening and closing intake valves and exhaust valves (not shown) of the engine 1. The engine 1 of this embodiment has a so-called overhead valve train.

[0031] The camshaft case 314 is disposed near the left side surface 301 in the cylinder portion of the cylinder block 6. The camshaft 313 and the camshaft case 314 are disposed along the crankshaft axis 300. Furthermore, the substantially triangular portion and the linear portion 307a, 308a of the second left reinforcing rib 307 and the third left reinforcing rib 308 formed on the left side surface 301 of the cylinder block 6 are disposed close to the position of the camshaft case 314 in a side view, more specifically, they are disposed at positions overlapping the position of the camshaft case 314.

[0032] In this embodiment, the rigidity around the camshaft case portion 314 is improved by the left second reinforcing rib 307 and the left third reinforcing rib 308, which prevents distortion of the camshaft case portion 314. This prevents fluctuations in the rotational resistance and rotational friction of the camshaft 313 caused by distortion of the camshaft case portion 314, allowing the camshaft 313 to rotate appropriately and the intake valves and exhaust valves (not shown) to open and close appropriately.

[0033] Furthermore, some of the lubricating oil passages formed in cylinder block 6, in this case lubricating oil suction passage 315 and lubricating oil supply passage 316, are located near right side surface 302 on the skirt portion of cylinder block 6. Lubricating oil supply passage 316 is located near the cylinder portion on the skirt portion of cylinder block 6. Lubricating oil suction passage 315 is located near the oil pan rail portion relative to lubricating oil supply passage 316.

[0034] One end of the lubricating oil suction passage 315 opens to the underside of the oil pan rail portion of the cylinder block 6 (the surface facing the oil pan 11) and is connected to a lubricating oil suction pipe (not shown) arranged in the oil pan 11. The other end of the lubricating oil suction passage 315 opens to the front side surface 303 of the cylinder block 6 and is connected to the suction port of the oil pump 12 (see FIG. 11 ) fixed to the front side surface 303. One end of the lubricating oil supply passage 316 opens to the front side surface 303 of the cylinder block 6 at a position different from the opening of the lubricating oil suction passage 315 and is connected to the discharge port of the oil pump 12. The other end of the lubricating oil supply passage 316 opens to an oil cooler bracket mounting seat 318 protruding from the right side surface 302 of the cylinder block 6 and is connected to the suction port of the oil cooler 13 (see FIG. 4 , etc.) arranged on the oil cooler bracket mounting seat 318. In addition to the lubricating oil suction passage 315 and the lubricating oil supply passage 316, other lubricating oil passages are formed in the cylinder block 6.

[0035] On the right side surface 302 of the cylinder block 6, the right first reinforcing rib 310 is disposed near the position of the lubricating oil supply passage 316 in a side view, more specifically, it is disposed so as to overlap the position of the lubricating oil supply passage 316 in a side view. In addition, the right second reinforcing rib 311 is disposed near the position of the lubricating oil suction passage 315 in a side view. The reinforcing ribs 310, 311 and the passages 315, 316 each extend along the crank axis 300.

[0036] In this embodiment, the right housing bracket portion 305, the right first reinforcing rib 310, and the right second reinforcing rib 311 can improve the cooling efficiency in the vicinity of the lubricating oil suction passage 315, the oil pump 12, and the lubricating oil supply passage 316. In particular, the right first reinforcing rib 310, which is positioned so as to overlap the lubricating oil supply passage 316 in a side view, efficiently dissipates heat in the vicinity of the lubricating oil supply passage 316 to the outside. This reduces the temperature of the lubricating oil flowing into the oil cooler 13, and reduces the amount of heat exchange required in the oil cooler 13.

[0037] Next, the gear train structure of the engine 1 will be described with reference to Figures 10 to 16. A gear case 330 is formed in a space surrounded by the front side surface 303 of the cylinder block 6, housing bracket portions 304 and 305, and the flywheel housing 7. As shown in Figures 12 and 14, the front ends of the crankshaft 5 and camshaft 313 are disposed so as to protrude from the front side surface 303 of the cylinder block 6. A crank gear 331 is fixed to the front end portion of the crankshaft 5. A cam gear 332 is fixed to the front end portion of the camshaft 313. A donut-shaped camshaft pulser 339 is bolted to the side of the cam gear 332 facing the flywheel housing 7 so as to rotate integrally with the cam gear 332.

[0038] As shown in Figures 12, 13, and 16, the fuel supply pump 15 provided in the right housing bracket portion 305 of the cylinder block 6 includes a fuel supply pump shaft 333 as a rotational shaft extending parallel to the rotational axis of the crankshaft 5. The front end of the fuel supply pump shaft 333 is disposed so as to protrude from the front side surface 305a of the right housing bracket portion 305. A fuel supply pump gear 334 is fixed to the front tip of the fuel supply pump shaft 333. As shown in Figure 13, the right housing bracket portion 305 of the cylinder block 6 has a fuel supply pump mounting seat 323 for mounting the fuel supply pump 15 at a position above the right first reinforcing rib 310. The fuel supply pump mounting seat 323 is formed with a fuel supply pump shaft insertion hole 324 large enough to allow the fuel supply pump gear 334 to pass through.

[0039] 11 and 12, oil pump 12 is disposed on the front side surface 305a of right housing bracket portion 305 below fuel supply pump gear 334, and includes oil pump shaft 335 as a rotation shaft that extends parallel to the rotation axis of crankshaft 5. An oil pump gear 336 is fixed to the front tip end of oil pump shaft 335.

[0040] An idle shaft 337 extending parallel to the rotational axis of the crankshaft 5 is provided in a region of the front side surface 303 of the cylinder block 6 that is surrounded by the crankshaft 5, the camshaft 313, the fuel supply pump shaft 333, and the oil pump shaft 335. The idle shaft 337 is fixed to the front side surface 303 of the cylinder block 6. An idle gear 338 is rotatably supported on the idle shaft 337.

[0041] The idle gear 338 is in mesh with four gears: the crank gear 331, the cam gear 332, the fuel supply pump gear 334, and the oil pump gear 336. The rotational power of the crankshaft 5 is transmitted from the crank gear 331 via the idle gear 338 to the cam gear 332, the fuel supply pump gear 334, and the oil pump gear 336. Therefore, the camshaft 313, the fuel supply pump shaft 333, and the oil pump shaft 335 rotate in conjunction with the crankshaft 5. In this embodiment, the gear ratios among the gears 331, 332, 334, 336, and 338 are set so that the camshaft 313 rotates once for every two rotations of the crankshaft 5, and the fuel supply pump shaft 333 and the oil pump shaft 335 rotate once for every one rotation of the crankshaft 5.

[0042] In this case, the cam gear 332 and the camshaft 313 are rotated in conjunction with the crank gear 331, which rotates together with the crankshaft 5, to drive a valve mechanism (not shown) provided in association with the camshaft 313, thereby opening and closing intake valves and exhaust valves (not shown) provided in the cylinder head 2. The fuel supply pump gear 334 and the fuel supply pump shaft 333 are rotated in conjunction with the crank gear 331, to drive the fuel supply pump 15, thereby pumping fuel from the fuel tank 118 to the common rail 16 and storing the high-pressure fuel in the common rail 16. The oil pump gear 336 and the oil pump shaft 335 are rotated in conjunction with the crank gear 331, to drive the oil pump 12, thereby supplying lubricating oil from the oil pan 11 to each sliding part, etc., via a lubricating oil suction passage 315, a lubricating oil supply passage 316, an oil cooler 13, an oil filter 14, etc. (details are omitted).

[0043] As shown in Figure 16, the fuel supply pump 15, which serves as an accessory that operates in conjunction with the rotation of the crankshaft 5, is fixed with bolts to a fuel supply pump mounting seat 323 of the right housing bracket portion 305. A first right-side reinforcing rib 310 is disposed adjacent to the fuel supply pump mounting seat 323. The first right-side reinforcing rib 310 is disposed directly below the fuel supply pump 15, and a second right-side reinforcing rib 311 is disposed directly below the first right-side reinforcing rib 310. The reinforcing ribs 310, 311 improve the rigidity of the fuel supply pump mounting seat 323 and can protect the fuel supply pump 15 by preventing foreign objects such as muddy water or flying stones from coming into contact with the fuel supply pump 15 from below.

[0044] Next, the gear case 330 that houses the gear train will be described with reference to Figures 10 to 12, 14, and 15. A block-side convex rib portion 321 that is joined to the flywheel housing 7 is provided along the periphery of the area including the front sides 303, 304a, and 305a of the cylinder block 6 and the left and right housing bracket portions 304 and 305. The block-side convex rib portion 321 has a notch 321a formed in the portion between the left and right oil pan rail portions of the cylinder block 6. When viewed from the side, the space between the end face of the block-side convex rib portion 321 and the front sides 303, 304a, and 305a forms a block-side gear case portion 322.

[0045] 14 and 15, the flywheel housing 7, made of, for example, cast iron, has a flywheel accommodating portion 401 that accommodates the flywheel 8. The flywheel accommodating portion 401 has a cylindrical shape with a bottom, formed by connecting a substantially cylindrical peripheral wall surface portion 402 that covers the outer periphery of the flywheel 8 with a rear wall surface portion 403 that covers the rear side (the surface on the cylinder block 6 side). The flywheel 8 is accommodated in the space surrounded by the peripheral wall surface portion 402 and the rear wall surface portion 403. The peripheral wall surface portion 402 is formed in a substantially truncated cone shape with a radius that decreases toward the rear wall surface portion 403. A crankshaft insertion hole 404, into which the crankshaft 5 is inserted, is formed in the center of the rear wall surface portion 403.

[0046] An annular housing-side ridge 405, which corresponds to the shape of the block-side ridge 321 of the cylinder block 6, is connected to the rear-side wall surface 403 so as to surround the position where the crankshaft insertion hole 404 is disposed. The center of the housing-side ridge 405 is disposed in a position shifted upward relative to the crankshaft insertion hole 404. The lower portion of the housing-side ridge 405 extends in the left-right direction and is disposed near the crankshaft insertion hole 404 and connected to the rear-side wall surface 403.

[0047] Additionally, the upper portion and left and right portions of the housing-side ridge portion 405 are disposed outside the rear wall surface portion 403. The front portion of the housing-side ridge portion 405 located outside the rear wall surface portion 403 and the front portion of the surrounding wall surface portion 402 are connected by an outer wall portion 406. The outer wall portion 406 has a curved, inclined shape that is convex in a direction away from the crankshaft 5. In the flywheel housing 7, the lower portion of the flywheel accommodating portion 401 is disposed so as to protrude in a direction away from the crankshaft 5 relative to the housing-side ridge portion 405.

[0048] In a side view, the space between the rear wall surface portion 403 and the end face of the housing side protruding rib portion 405 forms a housing side gear case portion 407. The housing side gear case portion 407 and the block side gear case portion 322 described above form a gear case 330.

[0049] A lightening space 408 is formed inside the flywheel housing 7 between the outer wall of the surrounding wall portion 402 of the flywheel accommodating portion 401 and the inner wall of the outer wall portion 406. A plurality of ribs 409 connecting the surrounding wall portion 402 and the outer wall portion 406 are arranged inside the lightening space 408. The flywheel housing 7 also has a starter mounting portion 411 that is connected to the surrounding wall portion 402 and the housing side ridge portion 405 on the outside of the housing side ridge portion 405 and has a starter mounting seat 410 that is flush with the housing side ridge portion 405. A through hole 412 is formed in the starter mounting portion 411, penetrating between the inner wall of the surrounding wall portion 402 and the starter mounting seat 410. The flywheel housing 7 is bolted to the front side 303 of the cylinder block 6 using 13 bolt holes 351 in the block side ridge portion 321 of the cylinder block 6 and bolt holes 353 in two housing bolt boss portions 352 on the front side 303.

[0050] As shown in Figures 10, 12, and 13, the left housing bracket portion 304 of the cylinder block 6 has a bracket recessed portion 325 whose peripheral edge is recessed relative to the peripheral edge of the flywheel housing 7. When the flywheel housing 7 is fixed to the cylinder block 6, the starter 20 is mounted in a starter mounting seat 410 of the flywheel housing 7 that is exposed below the bracket recessed portion 325. As shown in Figure 14, an annular ring gear 501 for the starter 20 and a crankshaft pulser 502 are fitted and fixed to the outer periphery of the flywheel 8 from opposite sides along the thickness direction of the flywheel 8. The starter 20 is disposed within the through hole 412 and has a pinion gear 503 (see Figure 12) that releasably meshes with the ring gear 501.

[0051] Around the starter mounting seat 410, the cast iron flywheel housing 7 is bolted to a block-side protruding portion 321 (see FIGS. 12 and 14) that is erected on the peripheral edge of the front side surface 304a of the left housing bracket portion 304. Furthermore, in the cylinder block 6, a left-side fourth reinforcing rib 309 that connects the left housing bracket portion 304 and the left side surface 301 is disposed near a bracket recessed portion 325 of the left housing bracket portion 304 that is adjacent to the starter mounting seat 410. This improves the rigidity around the starter mounting seat 410. In addition, the bracket recessed portion 325 of the left housing bracket portion 304 and the block-side protruding portion 321 (see FIG. 12) that is continuous with the bracket recessed portion 325 on the front side surface 303 and is provided near the starter mounting seat 410 also improve the rigidity around the starter mounting seat 410.

[0052] In this embodiment, the starter 20 can be attached to a location with high rigidity provided by the left-side fourth reinforcing rib 309, etc., which prevents the starter 20 from shifting position or deforming due to distortion of the starter mounting seat 410 or the left-side housing bracket portion 304, thereby preventing malfunction of the starter 20 and poor meshing between the pinion gear 503 of the starter 20 and the ring gear 501 of the flywheel 8.

[0053] Next, the common rail system 117 and the fuel system structure of the engine 1 will be described with reference to Figure 17. As shown in Figure 17, a fuel tank 118 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 117. Each injector 17 has an electromagnetically controlled fuel injection valve 119. The common rail system 117 has a cylindrical common rail 16. The common rail 16 is provided on the right side surface 302 of the cylinder block 6 and is arranged close to the intake manifold 3.

[0054] The suction side of the fuel supply pump 15 is connected to the fuel tank 118 via a fuel filter 121 and a low-pressure pipe 122. Fuel in the fuel tank 118 is sucked into the fuel supply pump 15 via the fuel filter 121 and the low-pressure pipe 122. On the other hand, the discharge side of the fuel supply pump 15 is connected to the common rail 16 via a high-pressure pipe 123. A high-pressure pipe connector 124 is provided in the middle of the cylindrical common rail 16 in the longitudinal direction, and an end of the high-pressure pipe 123 is connected to the high-pressure pipe connector 124 by screwing a high-pressure pipe connector nut 125.

[0055] The common rail 16 is also connected to the injectors 17 for each of the four cylinders via four fuel injection pipes 126. Fuel injection pipe connectors 127 for each of the four cylinders are provided in the longitudinal direction of the cylindrical common rail 16, and the ends of the fuel injection pipes 126 are connected to the fuel injection pipe connectors 127 by screwing fuel injection pipe connector nuts 128.

[0056] A return pipe connector 129 (pipe joint member) for returning surplus fuel, which limits the pressure of fuel in the common rail 16, is connected to one end of the common rail 16 in the longitudinal direction. The return pipe connector 129 is connected to the fuel tank 118 via a fuel return pipe 130. Excess fuel from the fuel supply pump 15 is sent to the return pipe connector 130 via a pump surplus fuel return pipe 131. Excess fuel from each injector 17 is sent to the return pipe connector 130 via an injector surplus fuel return pipe 132. In other words, the surplus fuel from the fuel supply pump 15, the surplus fuel from the common rail 16, and the surplus fuel from each injector 17 are joined at the return pipe connector 129 and collected in the fuel tank 118 via the fuel return pipe 130. The return pipe connector 129 may also be connected to the fuel tank 118 via a filter surplus fuel return pipe joint member (not shown) provided on the fuel filter 121.

[0057] A fuel pressure sensor 601 that detects the fuel pressure in the common rail 16 is provided at the end of the common rail 16 opposite the return pipe connector 129. 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 of the intake metering valve 602 of the fuel supply pump 15 is adjusted to adjust the fuel intake amount of the fuel supply pump 15, and ultimately the fuel discharge amount, while fuel from the fuel tank 118 is pressure-fed to the common rail 16 by the fuel supply pump 15, and the high-pressure fuel is stored in the common rail 16. The opening and closing of each fuel injection valve 119 is controlled by the engine controller 600, so that the high-pressure fuel in the common rail 16 is injected from each injector 17 into each cylinder of the engine 1. In other words, by electronically controlling each fuel injection valve 119, the injection pressure, injection timing, and injection period (injection amount) of the fuel supplied from each injector 17 can be controlled with high precision. This reduces nitrogen oxides (NOx) emitted from the engine 1. It also reduces noise and vibration of the engine 1. The engine controller 600 is also electrically connected to an electromagnetically driven pressure reducing valve 603 that adjusts the 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.

[0058] Next, with reference to Figure 18, a portion of the harness structure attached to the engine 1 will be described. A harness connector 701, which connects each component of the engine 1 to the engine controller 600 (see Figure 17) and the battery (not shown), is fixed to the right side surface 302 of the cylinder block 6 via a connector bracket 702. The harness connector 701 and harness bracket 702 are located in a region surrounded by the oil cooler 13, the oil filter 14, the fuel supply pump 15, and the common rail 16.

[0059] The main harness assembly 703 extending from the harness connector 701 passes between the right side surface 302 of the cylinder block 6 and the harness bracket 702 and is led to the lower side of the engine 1, and then passes along the straight portion 311a of the right second reinforcing rib 311 between the right side surface 302 and the oil filter 14 and is led to the rear side of the engine 1. Furthermore, the main harness assembly 703 curves upward of the engine 1 on the rear side of the oil filter 14, passes behind the oil cooler 13 and is led to the cylinder head 2 side.

[0060] Main harness assembly 703 branches into an intake / exhaust system harness assembly 704 and a fuel system harness assembly 705 near the joint surface between the cylinder head 2 and the cylinder block 6. Intake / exhaust system harness assembly 704 is led along the right side of the cylinder head 2 toward the upper side of the engine 1, and branches into an intake system harness assembly 706 and an exhaust system harness assembly 707 near the upper rear portion of the right side of the head cover 18. Intake system harness assembly 706 is led along the right side of the head cover 18 toward the front side of the engine 1. Exhaust system harness assembly 707 is led from the right side of the head cover 18 along the rear side to the left side of the engine 1.

[0061] The fuel system harness assembly 705 is led to the front side of the engine 1 through between the oil cooler 13 and the collector 25 of the EGR device 24, and branches into harnesses connected to the fuel pressure sensor 601 and pressure reducing valve 603 of the common rail 16, and the intake metering valve 602 and fuel temperature sensor 604 of the fuel supply pump 15 shown in Figure 17.

[0062] The layout of the common rail 16 and its surroundings will be described with reference to Figures 19 to 23. The roughly cylindrical common rail 16 is attached to an upper, front portion of the right side surface 302 of the cylinder block 6, with its longitudinal direction aligned with the crankshaft axis 300 (see Figure 11). The common rail 16 is located below the intake manifold 3, which is molded integrally with the right side surface of the cylinder head 2. The front end (one end) of the common rail 16 is located on the gear case 330 and the flywheel housing 7. The common rail 16 is provided at its front end with a return pipe joint 129 (pipe joint member) for returning excess fuel, which limits the pressure of fuel in the common rail 16; for example, the return pipe joint 129 is located on the flywheel housing 7.

[0063] A bracket recess 620 provided in the right housing bracket 305 of the cylinder block 6 and a housing recess 621 provided in the flywheel housing 7 are disposed near the upper front corner of the right side surface 302 of the cylinder block 6. As shown in Fig. 19, the recesses 621, 622 are formed so that the joint between the flywheel housing 7 and the right housing bracket 305 near the upper front corner of the right side surface 302 is lower than the top surface of the cylinder block 6. This allows the front end of the common rail 16 attached to the right side surface 302 of the cylinder block 6 to pass over the recesses 621, 622 and extend above the flywheel housing 7.

[0064] The return pipe joint 129 includes a connection portion 130a to which one end of a fuel return pipe 130 (see FIG. 17) is connected, a connection portion 131a to which one end of a pump surplus fuel return pipe 131 (see FIG. 17) is connected, and a connection portion 132a to which one end of an injector surplus fuel return pipe 132 (see FIG. 17) is connected. The return pipe joint 129 is provided with an internal flow path (not shown) connecting the connection portions 130a, 131a, and 132a, and a fuel pressure regulating valve (not shown) disposed between the internal flow path and the internal space of the common rail 16. In addition, the cylinder head 2 is provided with an excess fuel outlet 132b from the injector 17 (see FIG. 17) near the intersection of the right side surface 302 and the front side surface 303 (see FIG. 12) of the cylinder block 6, or in this embodiment, near the corner where the right side surface and the front side surface of the cylinder head 2 intersect, more specifically, at a position near the upper front end of the right side surface of the cylinder head 2. An injector surplus fuel return pipe 132c is connected between the surplus fuel outlet 132b and the connection part 132a of the return pipe joint 129. The surplus fuel outlet 132b is also connected to a surplus fuel passage (not shown) formed inside the side wall of the cylinder head 2 and to the surplus fuel outlet of each injector 17 (see FIG. 17) via an injector surplus fuel return pipe 132 (see FIG. 17) that is arranged inside the cylinder head 2.

[0065] A connector 601a of a fuel pressure sensor 601 of the common rail 16 and a connector 603a of a pressure reducing valve 603, which are electrically connected to an engine controller 600 (see FIG. 17), are disposed below the intake manifold 3 of the cylinder head 2. As shown in FIGS. 13 and 23, an uneven surface region 611 corresponding to the shape of a water rail 610 (cooling water passage) inside the cylinder block 6 is formed on the right side surface 302 of the cylinder block 6. The connector 601a of the fuel pressure sensor 601 is disposed above a recessed region 612 of the uneven surface region 611, and a connecting portion of the connector 601a is disposed facing the recessed region 612 in a side view. The connecting portion of the connector 603a of the pressure reducing valve 603 is disposed facing, for example, to the right side of the engine 1.

[0066] Four fuel injection pipes 126 extending from the common rail 16 toward the cylinder head 2 are connected to each injector 17 (see FIG. 17 ) through between the cylinder head 2 and the EGR device 24 (exhaust gas recirculation device). As shown in FIG. 22 , the middle portions of the four fuel injection pipes 126 are attached to the cylinder head 2 by fuel injection pipe fixtures 614 attached to the cylinder head 2 directly or via spacer members 613. Fixing the middle portions of the fuel injection pipes 126 to the cylinder head 2 reduces vibration of the fuel injection pipes 126 and prevents damage to the fuel injection pipes 126 due to vibration. In this embodiment, the middle portions of two of the four fuel injection pipes 126 located on the front side of the engine 1 are fixed to the cylinder head 2 via substantially cylindrical spacer members 613. By adjusting the spacer member 613 to a desired length, the middle part of the fuel injection pipe 126 can be fixed at a position any distance away from the side surface of the cylinder head 2, and the fuel injection pipe 126 can be routed in any shape without changing the design of the surface shape of the cylinder head 2.

[0067] 20, the fuel supply pump 15 attached to the right housing bracket portion 305 of the cylinder block 6 is disposed below the EGR device 24. As described above, the right-side first reinforcing rib 310 is disposed directly below the fuel supply pump 15, and the right-side second reinforcing rib 311 is disposed directly below the right-side first reinforcing rib 310, thereby preventing foreign matter such as muddy water or flying stones from coming into contact with the fuel supply pump 15 from below (see FIG. 16).

[0068] In the engine 1 of this embodiment, one end of the common rail 16 attached to the right side surface 302 (one side) of the cylinder block 6 is disposed above the flywheel housing 7, so the area occupied by the arrangement region of the common rail 16 on the right side surface 302 of the cylinder block 6 can be made smaller compared to a configuration in which the entire common rail 16 is disposed on the right side surface 302 of the cylinder block 6. This improves the degree of freedom in the layout of other components on the right side surface 302 of the cylinder block 6. For example, in the engine device 1 of this embodiment, the oil cooler 13 is disposed on the rear side of the engine 1 at the rear end of the common rail 16, and the oil cooler 13 can be placed close to the intake manifold 3 and the EGR device 24, thereby realizing a compact arrangement of these components.

[0069] In the engine 1 of this embodiment, the connector 601a of the fuel pressure sensor 601 of the common rail 16 and the connector 603a of the pressure reducing valve 603, which are electrically connected to the engine controller 600, are disposed below the intake manifold 3 that is integrally molded with the cylinder head 2, so that the connectors 601a, 603a can be protected from contact with foreign matter by the intake manifold 3. The EGR device 24 attached to the intake manifold 3 also protects the connectors 601a, 603a in the same manner.

[0070] In addition, the connection port of connector 601a is arranged, in a side view, facing the concave portion 612 of the uneven surface portion 611 that corresponds to the shape of the water rail 610, so that the harness-side connector can be attached to connector 601a along the concave portion 612, improving the workability of harness attachment. Furthermore, compared to a configuration in which the connection port of connector 601a is arranged facing outward from engine 1, connector 601a can be arranged closer to the cylinder block 6, thereby reducing the overall width of engine 1.

[0071] Furthermore, in the engine 1 of this embodiment, the common rail 16 is provided with a return pipe connector 129 for returning surplus fuel at its front end, and surplus fuel outlets 132b from each injector 17 are provided in the cylinder head 2 near the intersection of the right side surface 302 and the front side surface 303 of the cylinder block 6 in a plan view. Because the return pipe connector 129 is disposed above the flywheel housing 7, the injector surplus fuel return pipe 132c (surplus fuel return path) connecting the connection portion 132a of the return pipe connector 129 and the surplus fuel outlet 132b can be made short and simple. This eliminates the problem of the conventional technology in which the surplus fuel return path from the injector 17 was long and complicated. Furthermore, for example, when a fuel filter 121 (see FIG. 17) is mounted on a work machine or vehicle equipped with the engine 1, the empty space above the flywheel housing 7 can be used to shorten and simplify the piping path between the connection portion 130a of the return pipe connector 129 and the fuel filter 121, and the degree of freedom in designing the piping path is improved.

[0072] Furthermore, in the engine 1 of this embodiment, an EGR device 24 that mixes a portion of the exhaust gas discharged from the exhaust manifold 4 into fresh air is connected to the intake manifold 3, and four fuel injection pipes 126 extending from the common rail 16 toward the cylinder head 2 pass between the cylinder head 2 and the EGR device 24. This allows each fuel injection pipe 126 to be protected by the EGR device 24, and eliminates problems that occur in conventional technology in which the fuel injection pipes are attached to the outer periphery of the engine device, such as deformation of the fuel injection pipes or fuel leakage due to contact with other components or falling of foreign objects during transportation of the engine device.

[0073] Furthermore, in the engine 1 of this embodiment, the fuel supply pump 15, which is attached to the cylinder block 6 and supplies fuel to the common rail 16, is disposed below the EGR device 24. This protects the fuel supply pump 15 from contact with foreign objects from above, such as tools being dropped during assembly, and prevents damage to the fuel supply pump 15.

[0074] Furthermore, the fuel supply pump 15 is attached to a right housing bracket portion 305 that protrudes from the right side surface 302 of the cylinder block 6, and reinforcing ribs 310, 311 that connect the right side surface 302 and the right housing bracket portion 305 are arranged below the fuel supply pump 15. This makes it possible to protect the fuel supply pump 15 from contact with foreign objects from below, such as flying stones, and further prevents damage to the fuel supply pump 15.

[0075] 20, a space is provided between the oil cooler 13 and the fuel supply pump 15 so that the fuel supply pump 15, with the fuel supply pump gear 334 (see FIG. 12) fixed thereto, can be removed from the right housing bracket portion 305 without removing the oil cooler 13. As shown in FIG. 18, by arranging a harness connector 701 and a harness bracket 702 between the oil cooler 13 and the fuel supply pump 15, the space between the oil cooler 13 and the fuel supply pump 15 can be effectively utilized, and the harness connector 701 can be positioned in a position surrounded by the oil cooler 13, oil filter 14, fuel supply pump 15, and EGR device 24 for protection.

[0076] The configuration of each part in the present invention is not limited to the illustrated embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0077] 1 engine 2. Cylinder head 3. Intake manifold 5 crankshaft 6 Cylinder block 7 Flywheel housing 8 Flywheel 15 Fuel supply pump 16 Common rail 17 Injector (fuel injection device) 24 EGR device (exhaust gas recirculation device) 129 Return pipe connector (pipe joint component) 300 Crank shaft center 302 Right side (one side) 303 Front side (one side) 305 Right side housing bracket 310 Right side first reinforcing rib 311 Right side second reinforcing rib 601a, 603a common rail connector 610 Water rail (cooling water passage) 611 Uneven shaped part 612 Concave area

Claims

1. In an engine system equipped with a common rail and a fuel supply pump, A plurality of surplus fuel return pipes are connected to an end of the common rail, The engine device, wherein the fuel supply pump is located below the common rail.

2. In an engine system equipped with a common rail and a fuel supply pump, A plurality of surplus fuel return pipes are connected to an end of the common rail, an engine device, wherein one end of the common rail and the fuel supply pump are connected to one of the surplus fuel return pipes;

3. In an engine system equipped with a common rail and a fuel supply pump, A plurality of surplus fuel return pipes are connected to an end of the common rail, the fuel supply pump is located below the common rail, The fuel supply pump is attached to a cylinder block of the engine unit.

4. In an engine system equipped with a common rail and a fuel supply pump, A plurality of surplus fuel return pipes are connected to an end of the common rail, the fuel supply pump is located below the common rail, An engine apparatus, wherein at least a portion of the surplus fuel return pipe is disposed between one end of the common rail and the fuel supply pump.

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