Lubricating oil supply device, diesel engine, and method for starting diesel engine

Abstract

This lubricating oil supply device for supplying lubricating oil to a sliding part of a high-pressure fuel pump of a diesel engine, comprises: a lubricating oil line connecting the high-pressure fuel pump and a lubricating oil storage part in which the lubricating oil is stored; an oil pump for supplying the lubricating oil sucked up from the lubricating oil storage part to the sliding part of the high-pressure fuel pump through the lubricating oil line; and an oil reservoir provided on the upstream side of the high-pressure fuel pump in the lubricating oil line. The oil reservoir includes an inflow port into which the lubricating oil flows, and an outflow port from which the lubricating oil flows out, the outflow port being located at a position lower than the inflow port. The outflow port of the oil reservoir is located at a position lower than the outlet of the lubricating oil line.

Description

Lubricating oil supply device, diesel engine, and method for starting diesel engine

[0001] This disclosure relates to a lubricating oil supply device for supplying lubricating oil to sliding parts of a high-pressure fuel pump of a diesel engine. This application claims priority to Japanese Patent Application No. 2024-128747, filed with the Japan Patent Office on August 5, 2024, the contents of which are incorporated herein by reference.

[0002] For example, Patent Document 1 discloses a turbocharger configured to supply lubricating oil between a rotor shaft of a compressor and a bearing that rotatably supports the rotor shaft.

[0003] JP 2012-57544 A

[0004] Diesel engines are equipped with a high-pressure fuel pump that pressurizes fuel for injection into combustion chambers. The sliding parts of the high-pressure fuel pump (e.g., the contact portion between the camshaft and the tappet roller) are subjected to high pressure immediately after starting the diesel engine. Therefore, if lubricating oil is not supplied to the sliding parts of the high-pressure fuel pump immediately after starting the diesel engine, the high-pressure fuel pump may be damaged. However, the technology described in Patent Document 1 does not disclose or suggest a configuration for quickly supplying lubricating oil between the rotor shaft and the bearing immediately after starting the turbocharger, because the gas pressure is low immediately after starting the turbocharger. Therefore, with the technology described in Patent Document 1, there is a time lag between starting the turbocharger and supplying lubricating oil between the rotor shaft and the bearing.

[0005] The present disclosure has been made in consideration of the above-described problems, and aims to provide a lubricating oil supply device that can lubricate sliding parts of a high-pressure fuel pump and suppress damage to the high-pressure fuel pump even immediately after starting a diesel engine.

[0006] In order to achieve the above object, the lubricating oil supply device according to the present disclosure is a lubricating oil supply device for supplying lubricating oil to sliding parts of a high-pressure fuel pump of a diesel engine, and includes a lubricating oil line connecting a lubricating oil reservoir in which the lubricating oil is stored to the high-pressure fuel pump, an oil pump for supplying the lubricating oil drawn up from the lubricating oil reservoir to the sliding parts of the high-pressure fuel pump via the lubricating oil line, and an oil sump provided on the lubricating oil line upstream of the high-pressure fuel pump, wherein the oil sump includes an inlet through which the lubricating oil flows and an outlet through which the lubricating oil flows out that is located lower than the inlet, and the outlet of the oil sump is located lower than the outlet of the lubricating oil line.

[0007] According to the lubricant oil supply device of the present disclosure, even immediately after the start of the diesel engine, it is possible to lubricate the sliding parts of the high-pressure fuel pump and suppress damage to the high-pressure fuel pump.

[0008] FIG. 1 is a diagram schematically showing an example of the configuration of a high-pressure fuel pump. FIG. 2 is a diagram schematically showing the configuration of a lubricating oil supplying device according to an embodiment. FIG. 3 is a diagram schematically showing the configuration of an oil reservoir according to an embodiment. FIG. 4 is a diagram schematically showing an example of the configuration of a pressure regulating device according to an embodiment. FIG. 5 is a diagram for explaining the action and effect of the lubricating oil supplying device according to an embodiment. FIG. 6 is a flowchart of a start-up method for a diesel engine equipped with a lubricating oil supplying device according to an embodiment.

[0009] A lubricating oil supply device, a diesel engine, and a method for starting a diesel engine according to embodiments of the present disclosure will be described below with reference to the drawings. The embodiments show one aspect of the present disclosure, but do not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0010] A lubricating oil supply device according to the present disclosure is provided in a diesel engine and supplies lubricating oil to sliding parts of a high-pressure fuel pump of the diesel engine. The high-pressure fuel pump is a fuel supply device that supplies high-pressure fuel to injectors of the diesel engine, and is, for example, a mechanically configured in-line pump or a high-pressure pump that pressure-feeds fuel to a common rail.

[0011] <High-Pressure Fuel Pump> Figure 1 is a diagram that schematically shows an example of the configuration of a high-pressure fuel pump 100. As shown in Figure 1, the high-pressure fuel pump 100 includes a plunger 102, a tappet roller 104, and a camshaft 106. The high-pressure fuel pump 100 further includes a housing 103 that defines a cam chamber 101 that accommodates the tappet roller 104 and the camshaft 106 therein, and a cylinder 108 that is attached to the housing 103.

[0012] The plunger 102 is accommodated in the cylinder 108 so as to reciprocate axially within the cylinder 108. An opening of the cylinder 108 on the side opposite to the camshaft 106 side is covered by a cylinder head 110. The high-pressure fuel pump 100 has a pressurization chamber 107 defined by the plunger 102, the cylinder 108, and the cylinder head 110. The high-pressure fuel pump 100 reciprocates the plunger 102 in response to rotation of the camshaft 106, draws fuel F into the pressurization chamber 107, compresses the drawn fuel F, and discharges it from the pressurization chamber 107.

[0013] The tappet roller 104 abuts against the camshaft 106 and converts the rotation of the camshaft 106 into linear reciprocating motion, transmitting the motion to the plunger 102. In the embodiment illustrated in FIG. 1 , the tappet roller 104 is held by a tappet 112. The tappet 112 is connected to the plunger 102 and has a groove 112a formed therein for accommodating and holding the tappet roller 104. The tappet 112 is disposed closer to the camshaft 106 than the cylinder 108. The high-pressure fuel pump 100 further includes a pump spring 114 for urging the plunger 102 and the tappet roller 104 toward the camshaft 106. The pump spring 114 is disposed in a pump spring chamber 115 formed between the cylinder 108 and the tappet 112, with one end connected to the cylinder 108 and the other end connected to the tappet 112.

[0014] When the high-pressure fuel pump 100 is operating, the cam chamber 101 is filled with the lubricating oil X supplied from the lubricating oil supply device 1. The tappet roller 104 rolls and slides with an oil film of the lubricating oil X formed between it and the camshaft 106. Similarly, the tappet roller 104 rolls and slides with an oil film of the lubricating oil X formed between it and the tappet 112. In the present disclosure, the abutting state of the tappet roller 104 includes not only a state in which the tappet roller 104 is in direct contact with the camshaft 106 or the tappet 112, but also a state in which an oil film is interposed between the tappet roller 104 and the camshaft 106 or the tappet 112.

[0015] Hereinafter, an example will be described in which the lubricating oil supplying device 1 supplies the lubricating oil X to the cam chamber 101. That is, the configuration, operation, and effects of the lubricating oil supplying device 1 will be described in which the sliding part of the high-pressure fuel pump 100 is the cam chamber 101.

[0016] <Lubricant Oil Supplying Apparatus> (Configuration) Fig. 2 is a diagram schematically showing the configuration of a lubricant oil supplying apparatus 1 according to one embodiment. As shown in Fig. 2, the lubricant oil supplying apparatus 1 includes a lubricant oil line 2, an oil pump 4, and an oil reservoir 6. In the embodiment shown in Fig. 2, the lubricant oil supplying apparatus 1 further includes a strainer 8, an oil cooler 10, an oil filter 12, and a pressure regulating device 14.

[0017] The lubricant oil line 2 connects a lubricant oil reservoir 120 in which lubricant oil X is stored to the high-pressure fuel pump 100. The lubricant oil reservoir 120 is formed with a reservoir space 121 for storing the lubricant oil X, and is, for example, an oil pan mounted on the diesel engine E. The lubricant oil reservoir 120 is disposed below the high-pressure fuel pump 100 in the up-down direction D1. The lubricant oil line 2 communicates between the cam chamber 101 and the reservoir space 121. The lubricant oil line 2 has an inlet 2a at one end that opens to the reservoir space 121, and an outlet 2b at the other end that opens to the cam chamber 101.

[0018] The oil pump 4 supplies the lubricating oil X drawn up from the storage space 121 of the lubricating oil reservoir 120 to the cam chamber 101 of the high-pressure fuel pump 100 via the lubricating oil line 2. The oil pump 4 is configured to be driven by the diesel engine E. That is, the oil pump 4 stops when the diesel engine E stops. The strainer 8 is provided on the lubricating oil line 2 closer to the lubricating oil reservoir 120 than the oil pump 4, and filters the lubricating oil X drawn up by the oil pump 4. Note that the present disclosure does not limit the destination of the lubricating oil X drawn up by the oil pump 4 to the cam chamber 101 (the sliding part of the high-pressure fuel pump 100). The oil pump 4 may supply the lubricating oil X to a location other than the cam chamber 101 of the high-pressure fuel pump 100 (for example, between the cylinder and piston of the diesel engine E) via a branch line (not shown) branching off from the lubricating oil line 2.

[0019] The oil cooler 10, oil filter 12, and pressure regulator 14 are each provided on the lubricating oil line 2 closer to the high-pressure fuel pump 100 than the oil pump 4. The oil cooler 10 cools the lubricating oil X discharged from the oil pump 4. The oil filter 12 includes a mesh with openings capable of capturing foreign matter smaller than that of the strainer 8, and filters the lubricating oil X cooled by the oil cooler 10. The pressure regulator 14 is provided on the lubricating oil line 2 closer to the lubricating oil reservoir 120 than the oil sump 6 (on the opposite side from the high-pressure fuel pump 100). The pressure regulator 14 is located between the oil filter 12 and the oil sump 6 in the lubricating oil line 2. The pressure regulator 14 adjusts the pressure of the lubricating oil X that has passed through the oil filter 12 to a predetermined pressure. The specific configuration of the pressure regulator 14 will be described later.

[0020] The oil reservoir 6 is located upstream of the high-pressure fuel pump 100 in the lubricant line 2. The oil reservoir 6 has an inlet 6a through which the lubricant X flows from the lubricant line 2 and an outlet 6b through which the lubricant X flows into the lubricant line 2. The outlet 6b is located lower than the inlet 6a in the vertical direction D1. The outlet 6b is located lower than the outlet 2b of the lubricant line 2 in the vertical direction D1. In one embodiment, the inlet 2a of the lubricant line 2, which corresponds to the connection position of the lubricant reservoir 120, is defined as 0% of the length of the lubricant line 2, and the distance increases from the inlet 2a toward the outlet 2b of the lubricant line 2, which corresponds to the connection position of the high-pressure fuel pump 100, with the outlet 2b being defined as 100% of the length of the lubricant line 2. The oil reservoir 6 is located within a range of 50% to less than 100% of the length of the lubricant line 2. More specifically, the oil reservoir 6 is located within a range of 80% to less than 100% of the length of the lubricant line 2. In other words, the oil reservoir 6 is disposed immediately before the high-pressure fuel pump 100 .

[0021] In one embodiment, the storage volume V of the oil reservoir 6 that can store the lubricant X is 0.8 to 5 times the volume of the portion of the lubricant line 2 from the lubricant reservoir 120 to the oil reservoir 6. More specifically, the storage volume V is 0.8 to 5 times the volume VL of the internal space of the lubricant line 2 from the inlet 2a of the lubricant line 2 to the inlet 6a of the oil reservoir 6.

[0022] 2 , the diesel engine E is provided with an electric pump 130 (a so-called priming pump) configured to supply lubricating oil X to the oil reservoir 6. The electric pump 130 is configured to be driven by electricity supplied from an auxiliary battery (not shown), and can be driven separately and independently of the diesel engine E.

[0023] 3 is a diagram schematically illustrating the configuration of an oil reservoir 6 according to one embodiment. As shown in FIG. 3, the oil reservoir 6 includes a box portion 16 in which a reservoir space 17 capable of storing lubricating oil X is formed. The box portion 16 is formed with an inlet 6a and an outlet 6b that open to the reservoir space 17. As described above, the outlet 6b is located lower than the inlet 6a in the vertical direction D1. As described above, the outlet 6b is located lower than the outlet 2b of the lubricating oil line 2 in the vertical direction D1. In some embodiments, the inlet 6a is located lower than the outlet 2b of the lubricating oil line 2 in the vertical direction D1.

[0024] 3 , outlet section 20, which is the portion of lubricant line 2 from outlet 6 b to outlet 2 b, includes a first horizontally extending portion 21 extending horizontally from outlet 6 b to approach high-pressure fuel pump 100, a second horizontally extending portion 22 extending horizontally from outlet 2 b to approach the oil reservoir, and a vertically extending portion 23 connecting first horizontally extending portion 21 and second horizontally extending portion 22 and extending in vertical direction D1. Each of first horizontally extending portion 21 and second horizontally extending portion 22 may be inclined with respect to the horizontal direction.

[0025] In the embodiment illustrated in Fig. 3, the lowest part 24 including the bottom end of the box part 16 is defined as 0% of the length of the box part 16 in the height direction D2 (up-down direction D1), and increases toward the top part 26 including the top end of the box part 16, with the top part 26 of the box part 16 being defined as 100% of the length of the box part 16 in the height direction. The outlet 6b is located within a range of 0% to 5% of the length of the box part 16 in the height direction. The inlet 6a is located within a range of 90% to 100% of the length of the box part 16 in the height direction. The height direction D2 and the up-down direction D1 of the box part 16 are the same direction.

[0026] In the embodiment illustrated in FIG. 3 , the box portion 16 includes an enlarged portion 28 that enlarges the cross-sectional area S of the reservoir space 17 cut horizontally from the outlet 6b toward the inlet 6a. The enlarged portion 28 is a part of the side portion 30 of the box portion 16 that covers the reservoir space 17 horizontally. The enlarged portion 28 increases the diameter of the reservoir space 17 from bottom to top. The lower end of the enlarged portion 28 is located below the outlet 6b in the vertical direction D1, and the upper end is located between the inlet 6a and the outlet 6b in the vertical direction D1. In some embodiments, the lower end of the enlarged portion 28 is located at the same position as the outlet 6b in the vertical direction D1. In some embodiments, the upper end of the enlarged portion 28 is located above the inlet 6a or at the same position as the inlet 6a in the vertical direction D1.

[0027] The pressure regulating device 14 will be described with reference to Fig. 4. Fig. 4 is a diagram schematically illustrating an example of the configuration of the pressure regulating device 14 according to one embodiment. As shown in Fig. 4, the pressure regulating device 14 includes a casing 40, a relief valve 42, a spring 44, and a cap 46.

[0028] The casing 40 has formed therein a relief path 41, a portion 43 of the lubricating oil line 2, a branch flow path 45, a pressure adjustment chamber 47, and a reservoir space 17 of the oil reservoir 6. The relief path 41 relieves a portion of the lubricating oil X from the lubricating oil line 2. At least a portion of the relief path 41 is located above the inlet 6a of the oil reservoir 6. The relief path 41 has an inlet 41a that opens to the pressure adjustment chamber 47. The relief path 41 extends upward from the inlet 41a. In the embodiment illustrated in FIG. 4 , the casing 40 has formed therein an outlet 41b of the relief path 41 that opens to the surface of the casing 40. The outlet 41b of the relief path 41 opens upward.

[0029] The lubricating oil X flowing through the relief path 41 is returned to, for example, a lubricating oil reservoir 120 (oil pan). The lubricating oil supplying device 1 further includes a return line 50 that connects the outlet 41b of the relief path 41 with the reservoir space 121. The return line 50 includes a folded portion 52 that extends upward from the outlet 41b of the relief path 41 and then downward.

[0030] 4, the reservoir space 17 is formed within the casing 40. In other words, the oil reservoir 6 is configured integrally with the pressure regulating device 14. A portion 43 of the lubricating oil line 2 is formed within the casing 40 so as to guide the lubricating oil X that has passed through the oil filter 12 to the oil reservoir 6. The branch flow path 45 branches off from the portion 43 of the lubricating oil line 2 and connects the portion 43 of the lubricating oil line 2 with the pressure regulating chamber 47.

[0031] The pressure adjustment chamber 47 has a longitudinal direction D3 that is inclined with respect to the vertical direction D1. One end of the pressure adjustment chamber 47 is located within the casing 40 and is closed. The other end of the pressure adjustment chamber 47 is located on the surface of the casing 40 and is open. The relief valve 42 and the spring 44 are disposed inside the pressure adjustment chamber 47. The opening of the pressure adjustment chamber 47 is closed by a cap 46. In the embodiment illustrated in FIG. 4 , the reservoir space 17 of the oil reservoir 6 extends long along the longitudinal direction D3 of the pressure adjustment chamber 47.

[0032] The relief valve 42 moves within the pressure adjustment chamber 47 along the longitudinal direction D3 to open or close the relief path 41. The relief valve 42 divides the pressure adjustment chamber 47 into an inflow space 49 into which the lubricating oil X flows and a spring chamber 51 in which the spring 44 is disposed. The inflow space 49 opens to the branch flow path 45, and the lubricating oil X flows in via the branch flow path 45. The spring chamber 51 is formed by separating the relief valve 42 from the cap 46 in the longitudinal direction D3. One end of the spring 44 is connected to the relief valve 42, and the other end is connected to the cap 46. The spring 44 biases the relief valve 42 in a valve-closing direction. In other words, the spring 44 biases the relief valve 42 to one side in the longitudinal direction D3.

[0033] (Functions and Effects) The functions and effects of the lubricant oil supplying device 1 according to one embodiment will be described. FIG. 5 is a diagram illustrating the functions and effects of the lubricant oil supplying device 1 according to one embodiment, and is a graph in which the horizontal axis represents elapsed time and the vertical axis represents the amount of lubricant oil X in the cam chamber 101. The solid line L1 represents the amount of lubricant oil X supplied to the cam chamber 101 from the lubricant oil supplying device 1 according to one embodiment, and the dotted line L2 represents the amount of lubricant oil supplied to the cam chamber 101 from a conventional lubricant oil supplying device. The dashed-dotted line L3 represents the rotation speed of the oil pump 4. Timing T0 represents the timing at which the oil pump 4 starts to be driven (the timing at which the oil pump 4 starts to rotate due to the rotation of the diesel engine E). Timing T1 represents the timing at which the oil pump 4 starts to discharge the fluid (mainly air) it has sucked in. Of the three rotation speeds T0, T1, and T2, timing T0 is the smallest and timing T2 is the largest.

[0034] If the high-pressure fuel pump 100 is located above the lubricating oil reservoir 120 (oil pan), when the diesel engine E is stopped, there is a risk that the lubricating oil X will return to the lubricating oil reservoir 120 through the lubricating oil line 2 due to the difference in head pressure between the lubricating oil X in the high-pressure fuel pump 100 and the lubricating oil X in the lubricating oil reservoir 120. When the diesel engine E is started without the lubricating oil line 2 filled with the lubricating oil X, in a conventional lubricating oil supply device, as shown in FIG. 5 , an air pressure-feeding period ΔT occurs during which air is supplied to the cam chamber 101 between the timing T1 when the oil pump 4 starts to discharge air and the timing T2 when the lubricating oil X is actually supplied to the cam chamber 101. Therefore, the tappet roller 104, the camshaft 106, and the tappet 112 slide without or with little lubrication, which may result in damage.

[0035] According to one embodiment, an oil sump 6 is provided in the lubricant line 2 upstream of the high-pressure fuel pump 100. The outlet 6b of the oil sump 6 is located lower than the inlet 6a and lower than the outlet 2b of the lubricant line 2. This allows lubricant X to be stored in the oil sump 6 when the diesel engine E is stopped. As shown in FIG. 5 , at timing T1 after the diesel engine E is started, the oil pump 4 can quickly supply the lubricant X stored in the oil sump 6 to the cam chamber 101. Therefore, even immediately after the diesel engine E is started, the tappet roller 104, the camshaft 106, and the tappet 112 slide with an oil film formed on their surfaces, thereby preventing damage to the tappet roller 104, the camshaft 106, and the tappet 112. The lubricant supplying device 1 according to the present disclosure is particularly advantageous for preventing damage to high-load components, such as the tappet roller 104 and the camshaft 106, that are subjected to high loads immediately after the diesel engine E is started. Furthermore, by limiting the protected parts to high load components, the oil reservoir 6 can be made smaller, and the lubricant oil supplying device 1 can be made more compact.

[0036] According to one embodiment, the outlet 6b is located within a range of 0% to 5% of the length of the box portion 16 in the height direction D2, so that most or all of the lubricating oil X stored in the oil reservoir 6 can be quickly supplied to the cam chamber 101 after the diesel engine E is started. This makes it possible to avoid a state in which an oil film is not formed on the surfaces of the tappet roller 104, the camshaft 106, and the tappet 112 immediately after the diesel engine E is started.

[0037] According to one embodiment, by setting the storage capacity V to be 0.8 times or more the volume VL of the internal space of the lubricant line 2, the lubricant X stored in the lubricant reservoir 120 can be supplied to the cam chamber 101 before the lubricant X supplied from the oil reservoir 6 to the cam chamber 101 is consumed. This prevents a shortage of the lubricant X to the cam chamber 101 and prevents damage to the tappet roller 104, the camshaft 106, and the tappet 112. Furthermore, according to one embodiment, by setting the storage capacity V to be 5 times or less the volume VL of the internal space of the lubricant line 2, it is possible to prevent the oil reservoir 6 from becoming larger than necessary.

[0038] According to one embodiment, the oil sump 6 is located within a range of 80% or more and less than 100% of the length of the lubricating oil line 2, that is, the oil sump 6 is located in the immediate vicinity of the high-pressure fuel pump 100. Therefore, as shown in FIG. 5 , at timing T1 after the start of the diesel engine E, the oil pump 4 can quickly supply the lubricating oil X stored in the oil sump 6 to the cam chamber 101. Furthermore, by locating the oil sump 6 in the immediate vicinity of the high-pressure fuel pump 100, the oil sump 6 can be made compact.

[0039] According to one embodiment, the oil reservoir 6 includes the box portion 16 including the enlarged portion 28, so that the pressure-receiving area of ​​the lubricating oil X stored in the oil reservoir 6 is increased, and the pressure generated by the oil pump 4 to pump the lubricating oil X to the high-pressure fuel pump 100 can be reduced.

[0040] According to one embodiment, at least a portion of the relief path 41 is located above the inlet 6a of the oil reservoir 6, so that when the diesel engine E is stopped, the lubricating oil X stored in the oil reservoir 6 can be prevented from flowing out into the lubricating oil reservoir 120 (oil pan) via the relief path 41.

[0041] According to one embodiment, the oil reservoir 6 is configured integrally with the pressure regulating device 14, so that a compact lubricating oil supplying device 1 in which the oil reservoir 6 and the pressure regulating device 14 are integrated can be provided.

[0042] According to one embodiment, the reservoir space 17 of the oil reservoir 6 extends long along the longitudinal direction D3 of the pressure adjusting chamber 47, so that the pressure adjusting device 14 can be made compact.

[0043] <Starting Method of Diesel Engine> Fig. 6 is a flowchart of a starting method of a diesel engine E including the lubricating oil supplying device 1 according to one embodiment. This diesel engine E also includes the above-described electric pump 130. As shown in Fig. 6, the starting method of the diesel engine E includes a preparation step S1, a lubrication step S2, and a fuel pumping step S3.

[0044] In the preparation step S1, for example, when a start button for starting the diesel engine E is pressed, the electric pump 130 is driven to supply the lubricating oil X to the oil sump 6. In the lubrication step S2, after the lubricating oil X has been supplied to the oil sump 6 in the preparation step S1, the oil pump 4 is driven to supply the lubricating oil X to the cam chamber 101. In the fuel pumping step S3, after the lubricating oil X has been supplied to the cam chamber 101 in the lubrication step S2, the high-pressure fuel pump 100 is driven to pump the fuel F to the injector. Then, the injector injects the fuel F into the combustion chamber, and the fuel F is burned in the combustion chamber, thereby starting the diesel engine E.

[0045] When starting the diesel engine E for the first time or when a long time has passed since the diesel engine E was stopped, there is a possibility that no lubricating oil X is stored in the oil sump 6 or that the amount of stored lubricating oil X is insufficient. According to the method illustrated in FIG. 6 , even if no lubricating oil X is stored in the oil sump 6, the electric pump 130 supplies the lubricating oil X to the oil sump 6 between timing T0 (when the oil pump 4 starts to operate) and timing T1 (when the oil pump 4 starts to discharge the air it has sucked). The oil pump 4 can then quickly supply the lubricating oil X stored in the oil sump 6 to the cam chamber 101 by the electric pump 130. Note that in some embodiments, if a sufficient amount of lubricating oil X is stored in the oil sump 6, the preparation step S1 is skipped.

[0046] The contents described in each of the above embodiments can be understood, for example, as follows.

[0047] [1] A lubricating oil supply device (1) according to the present disclosure is a lubricating oil supply device for supplying lubricating oil (X) to a sliding part (101) of a high-pressure fuel pump (100) of a diesel engine (E), comprising: a lubricating oil line (2) connecting a lubricating oil reservoir (120) in which the lubricating oil is stored to the high-pressure fuel pump; an oil pump (4) for supplying the lubricating oil drawn up from the lubricating oil reservoir to the sliding part of the high-pressure fuel pump via the lubricating oil line; and an oil sump (6) provided upstream of the high-pressure fuel pump in the lubricating oil line, wherein the oil sump includes an inlet (6a) through which the lubricating oil flows and an outlet (6b) through which the lubricating oil flows, the outlet being located lower than the inlet, and the outlet of the oil sump being located lower than an outlet (2b) of the lubricating oil line.

[0048] If the high-pressure fuel pump is located above the lubricating oil reservoir (oil pan), when the diesel engine is stopped, the head pressure difference between the high-pressure fuel pump and the lubricating oil reservoir may cause lubricating oil to flow through the lubricating oil line and return to the lubricating oil reservoir. Furthermore, if the diesel engine is started without lubricating oil in the lubricating oil line, the sliding parts of the high-pressure fuel pump will slide without or with little lubrication, which may result in damage to the high-pressure fuel pump. According to the configuration described in [1] above, an oil reservoir is provided in the lubricating oil line upstream of the high-pressure fuel pump. The outlet of the oil reservoir is located lower than the inlet and lower than the outlet of the lubricating oil line. Therefore, when the diesel engine is stopped, lubricating oil can be stored in the oil reservoir, and after the diesel engine is started, the lubricating oil stored in the oil reservoir can be quickly supplied to the sliding parts of the high-pressure fuel pump. Therefore, even immediately after starting the diesel engine, the sliding parts of the high-pressure fuel pump can be lubricated, thereby preventing damage to the high-pressure fuel pump. Due to the layout of the diesel engine and its peripheral devices, it is difficult to install the high-pressure fuel pump in a manner that does not cause a difference in head pressure relative to the lubricating oil reservoir.

[0049] [2] In some embodiments, in the configuration described in [1] above, the oil reservoir includes a box portion (16) in which a reservoir space (17) capable of storing the lubricating oil is formed, and when the lowest portion (24) of the box portion is defined as a position at 0% of the height direction (D2) of the box portion and the highest portion (26) of the box portion is defined as a position at 100% of the height direction length of the box portion, the outlet is located within a range of 0% to 5% of the height direction length of the box portion.

[0050] According to the configuration described in [2] above, most or all of the lubricating oil stored in the oil reservoir can be supplied to the sliding parts of the high-pressure fuel pump quickly after the diesel engine is started, thereby preventing the sliding parts of the high-pressure fuel pump from being left unlubricated immediately after the diesel engine is started.

[0051] [3] In some embodiments, in the configuration described in [1] or [2] above, the storage capacity (V) of the oil reservoir that can store the lubricating oil is 0.8 to 5 times the volume of the portion of the lubricating oil line from the lubricating oil storage section to the oil reservoir.

[0052] According to the configuration described in [3] above, by setting the storage capacity to 0.8 times or more the volume of the portion of the lubricating oil line from the lubricating oil storage portion to the oil sump, the lubricating oil stored in the lubricating oil storage portion can be supplied to the sliding portions of the high-pressure fuel pump before the lubricating oil supplied from the oil sump to the sliding portions of the high-pressure fuel pump is consumed. This prevents a shortage of lubricating oil to the sliding portions of the high-pressure fuel pump and prevents damage to the high-pressure fuel pump. Furthermore, by setting the storage capacity to 5 times or less the volume of the portion of the lubricating oil line from the lubricating oil storage portion to the oil sump, it is possible to prevent the oil sump from becoming larger than necessary.

[0053] [4] In some embodiments, in the configuration described in any one of [1] to [3] above, when the connection position of the lubricant oil reservoir is defined as a position at 0% of the length of the lubricant oil line and the connection position of the high-pressure fuel pump is defined as a position at 100% of the length of the lubricant oil line, the oil reservoir is located within a range of 50% or more and less than 100% of the length of the lubricant oil line.

[0054] According to the configuration described in [4] above, since the oil reservoir is disposed near the high-pressure fuel pump, lubricating oil can be supplied to the sliding parts of the high-pressure fuel pump quickly after the diesel engine is started.

[0055] [5] In some embodiments, in the configuration described in any one of [1] to [4] above, the oil reservoir includes a box portion (16) in which a reservoir space (17) capable of storing the lubricating oil is formed, and the box portion includes an expansion portion (28) that expands the cross-sectional area of ​​the reservoir space cut along the horizontal direction from the outlet toward the inlet.

[0056] According to the configuration described in [5] above, the pressure-receiving area of ​​the lubricating oil stored in the oil reservoir can be increased, and the pressure generated by the oil pump to pump the lubricating oil to the high-pressure fuel pump can be reduced.

[0057] [6] In some embodiments, in the configuration described in any one of [1] to [5] above, the pressure regulating device (14) is provided on the side of the lubricating oil line opposite the high-pressure fuel pump side relative to the oil reservoir, and a relief path (41) is formed to relieve a portion of the lubricating oil from the lubricating oil line, and at least a portion of the relief path is located above the inlet of the oil reservoir.

[0058] According to the configuration described in [6] above, when the diesel engine is stopped, the lubricating oil stored in the oil reservoir can be prevented from leaking out through the relief path.

[0059] [7] In some embodiments, in the configuration described in [6] above, the oil reservoir is configured integrally with the pressure regulating device.

[0060] According to the configuration described in [7] above, it is possible to provide a compact lubricating oil supply device in which the oil reservoir and the pressure regulator are integrated.

[0061] [8] In some embodiments, in the configuration described in [7] above, the pressure regulating device includes a casing (40) having a pressure regulating chamber (47) formed therein with a longitudinal direction, a relief valve (42) that opens or closes the relief path by moving in the longitudinal direction within the pressure regulating chamber, and a spring (44) that biases the relief valve in a closing direction, and the oil reservoir extends long along the longitudinal direction.

[0062] According to the configuration described in [8] above, the pressure regulating device can be made compact.

[0063] [9] In some embodiments, a diesel engine is provided with the lubricating oil supply device according to any one of [1] to [8] above.

[0064] According to the configuration described in [9] above, it is possible to provide a diesel engine that can suppress damage to the high-pressure fuel pump by supplying lubricating oil to the sliding parts of the high-pressure fuel pump immediately after startup.

[0065]

[10] In some embodiments, the method for starting a diesel engine according to [9] above, further comprising an electric pump (130) configured to supply the lubricating oil to the oil sump, comprises: a preparation step (S1) of supplying the lubricating oil to the oil sump by the electric pump; a lubrication step (S2) of driving the oil pump to supply the lubricating oil to the sliding portion of the high-pressure fuel pump after the preparation step; and a fuel pumping step (S3) of driving the high-pressure fuel pump after the lubrication step.

[0066] When a diesel engine is started for the first time or when a long time has passed since the diesel engine was stopped, there is a possibility that no lubricating oil is stored in the oil sump or that the amount stored therein is insufficient. According to the method described in

[10] above, even if no lubricating oil is stored in the oil sump, the electric pump supplies lubricating oil to the oil sump in advance, and the oil pump can quickly supply the lubricating oil stored in the oil sump to the sliding parts of the high-pressure fuel pump.

[0067] DESCRIPTION OF SYMBOLS 1 Lubricating oil supply device 2 Lubricating oil line 2a Inlet of lubricating oil line 2b Outlet of lubricating oil line 4 Oil pump 6 Oil reservoir 6a Inlet of oil reservoir 6b Outlet of oil reservoir 8 Strainer 10 Oil cooler 12 Oil filter 14 Pressure regulating device 16 Box portion 17 Reservoir space 20 Outlet portion of lubricating oil line 21 First horizontally extending portion 22 Second horizontally extending portion 23 Vertically extending portion 24 Lowest portion 26 Top portion 28 Expanded portion 30 Side portion 40 Casing 41 Relief path 41a Inlet 41b Outlet 42 Relief valve 44 Spring 45 Branch flow path 46 Cap 47 Pressure regulating chamber 49 Inflow space 50 Return line 51 Spring chamber 52 Turned portion 100 DESCRIPTION OF THE SYMBOLS 101 High-pressure fuel pump 101 Cam chamber 102 Plunger 103 Housing 104 Tappet roller 106 Camshaft 107 Pressurizing chamber 108 Cylinder 110 Cylinder head 112 Tappet 112a Tappet groove 114 Pump spring 115 Pump spring chamber 120 Lubricating oil storage section (oil pan) 121 Storage space 130 Electric pump D1 Vertical direction D2 Height direction of box section D3 Longitudinal direction of pressure regulating chamber F Fuel L1 Solid line (lubricating oil supply device according to one embodiment) L2 Dotted line (conventional lubricating oil supply device) L3 Dash-dotted line (oil pump rotation speed) S Cross-sectional area S1 Preparation step S2 Lubrication step S3 Fuel pumping step T0, T1, T2 Timing V Storage capacity VL Volume X Lubricating oil

Claims

1. A lubricating oil supply device for supplying lubricating oil to sliding parts of a high-pressure fuel pump of a diesel engine, comprising: a lubricating oil line connecting a lubricating oil reservoir in which the lubricating oil is stored to the high-pressure fuel pump; an oil pump for supplying the lubricating oil drawn up from the lubricating oil reservoir to the sliding parts of the high-pressure fuel pump via the lubricating oil line; and an oil sump provided upstream of the high-pressure fuel pump in the lubricating oil line, wherein the oil sump includes an inlet through which the lubricating oil flows and an outlet through which the lubricating oil flows out, the outlet being located lower than the inlet, and the outlet of the oil sump being located lower than the outlet of the lubricating oil line.

2. A lubricating oil supply device as described in claim 1, wherein the oil reservoir includes a box portion in which a reservoir space capable of storing the lubricating oil is formed, and when the lowest part of the box portion is defined as a position at 0% of the height of the box portion and the top part of the box portion is defined as a position at 100% of the height of the box portion, the outlet is located within a range of 0% to 5% of the height of the box portion.

3. A lubricating oil supply device according to claim 1 or 2, wherein the storage capacity of the oil reservoir for storing the lubricating oil is 0.8 to 5 times the volume of the portion of the lubricating oil line from the lubricating oil storage section to the oil reservoir.

4. A lubricating oil supply device according to claim 1 or 2, wherein, when the connection position of the lubricating oil reservoir is defined as a position at 0% of the length of the lubricating oil line and the connection position of the high-pressure fuel pump is defined as a position at 100% of the length of the lubricating oil line, the oil reservoir is located within a range of 50% or more and less than 100% of the length of the lubricating oil line.

5. A lubricating oil supply device as described in claim 1 or 2, wherein the oil reservoir includes a box portion in which a reservoir space capable of storing the lubricating oil is formed, and the box portion includes an expansion portion that expands the cross-sectional area of ​​the reservoir space cut horizontally from the outlet toward the inlet.

6. A lubricating oil supply device according to claim 1 or 2, further comprising a pressure regulating device provided on the side of the lubricating oil line opposite the high-pressure fuel pump side relative to the oil reservoir, the pressure regulating device having a relief path formed therein for relieving a portion of the lubricating oil from the lubricating oil line, and at least a portion of the relief path being located above the inlet of the oil reservoir.

7. The lubricating oil supply device according to claim 6, wherein the oil reservoir is integrally formed with the pressure regulator.

8. A lubricating oil supply device as described in claim 7, wherein the pressure regulating device includes a casing having a pressure regulating chamber formed therein with a longitudinal direction, a relief valve that opens or closes the relief path by moving in the longitudinal direction within the pressure regulating chamber, and a spring that urges the relief valve in a valve closing direction, and the oil reservoir extends long along the longitudinal direction.

9. A diesel engine equipped with the lubricating oil supply device according to claim 1 or 2.

10. A method for starting a diesel engine as claimed in claim 9, further comprising an electric pump configured to supply the lubricating oil to the oil reservoir, comprising: a preparation step of supplying the lubricating oil to the oil reservoir by the electric pump immediately before starting the diesel engine; a lubrication step of driving the oil pump to supply the lubricating oil to the sliding parts of the high-pressure fuel pump after the preparation step; and a fuel pumping step of driving the high-pressure fuel pump after the lubrication step.

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