Internal combustion engine systems, reciprocating units and vehicles

Abstract

To improve the energy efficiency of internal combustion engine systems while simplifying their configuration. [Solution] The internal combustion engine system comprises an internal combustion engine including a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod; a fuel gas passage connecting the combustion chamber to a fuel gas supply source; a compression chamber, a pump piston defining the compression chamber, and a reciprocating pump pressurizing the fuel gas in the fuel gas passage; a pump crankshaft supported by the engine crankcase and connected to the engine crankshaft; and a pump connecting rod connecting the pump piston to the pump crankshaft.

Description

Technical Field

[0001] The present disclosure relates to an internal combustion engine system, a reciprocating unit, and a vehicle.

Background Art

[0002] In the internal combustion engine system disclosed in Patent Document 1, a fuel tank is connected to an internal combustion engine via a fuel gas pipe. The fuel gas in the fuel gas pipe is pressurized by a pressure pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of Patent Document 1, the entire system becomes large. In particular, when mounting an internal combustion engine system on a vehicle, etc., downsizing of the entire system is desired.

[0005] Therefore, one aspect of the present disclosure aims to make the internal combustion engine system more compact.

Means for Solving the Problems

[0006] An internal combustion engine system according to one aspect of the present disclosure includes an internal combustion engine comprising: a combustion chamber; an engine piston defining the combustion chamber; an engine crankshaft; an engine connecting rod connecting the engine piston to the engine crankshaft; and an engine crankcase housing the engine crankshaft and the engine connecting rod; a fuel gas passage connecting the combustion chamber to a fuel gas supply source; a compression chamber; a pump piston defining the compression chamber; a reciprocating pump pressurizing the fuel gas in the fuel gas passage; a pump crankshaft supported by the engine crankcase and connected to the engine crankshaft; and a pump connecting rod connecting the pump piston to the pump crankshaft.

[0007] A reciprocating unit according to another aspect of the present disclosure comprises an internal combustion engine including a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod; a reciprocating pump including a compression chamber and a pump piston defining the compression chamber, which pressurizes the fuel gas in a fuel gas passage connecting the combustion chamber to a fuel gas supply source; and a pump reciprocating structure supported by the engine crankcase, which converts the rotation of the engine crankshaft into reciprocating motion and transmits it to the pump piston.

[0008] A vehicle according to one aspect of this disclosure comprises the internal combustion engine system or the reciprocating unit. [Effects of the Invention]

[0009] According to one aspect of this disclosure, an internal combustion engine system can be made more compact. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of a vehicle equipped with an internal combustion engine system according to the first embodiment. [Figure 2]Figure 2 is a block diagram of the controller and other components of the internal combustion engine system shown in Figure 1. [Figure 3] Figure 3 is a perspective view of the reciprocating unit, which consists of the internal combustion engine and reciprocating pump shown in Figure 1. [Figure 4] Figure 4 is a longitudinal cross-sectional view of the reciprocating unit shown in Figure 3. [Figure 5] Figure 5 is a cross-sectional view of the VV line in Figure 4. [Figure 6] Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 4. [Figure 7] Figure 7 is a cross-sectional view of a modified example of Figure 6. [Figure 8] Figure 8 is a diagram corresponding to Figure 4 of the reciprocating unit of the internal combustion engine system according to the second embodiment. [Figure 9] Figure 9 is a cross-sectional view taken along the line IX-IX in Figure 8. [Figure 10] Figure 10 is a diagram corresponding to Figure 4 of the reciprocating unit of the internal combustion engine system according to the third embodiment. [Figure 11] Figure 11 is a perspective view of the reciprocating unit of the internal combustion engine system according to the fourth embodiment. [Figure 12] Figure 12 is a cross-sectional view of the reciprocating unit shown in Figure 11, taken from the direction of the rotation axis. [Figure 13] Figure 13 is a perspective view of the reciprocating unit of the internal combustion engine system according to the fifth embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings.

[0012] (First Embodiment) FIG. 1 is a schematic view of a vehicle V equipped with an internal combustion engine system 1 according to the first embodiment. As shown in FIG. 1, the internal combustion engine system 1 is mounted on the vehicle V. The vehicle V may be a manned vehicle or an unmanned vehicle. The vehicle V is, for example, a vehicle equipped with drive wheels W. In the vehicle V, the driving force generated by the internal combustion engine E of the internal combustion engine system 1 is transmitted to the drive wheels W via the transmission TM. The vehicle V can be, for example, a two-wheeled vehicle, a three-wheeled vehicle, a four-wheeled vehicle, a railway vehicle, or the like. The drive wheels W are an example of a propulsion force generator that generates a propulsion force by the driving force generated by the internal combustion engine E of the internal combustion engine system 1. The vehicle V may be a ship, an aircraft, or the like. In that case, a propeller or a fan can be used as the propulsion force generator.

[0013] The internal combustion engine system 1 includes a fuel gas supply source 2. The fuel gas supply source 2 includes a liquid fuel tank 3 and a vaporizer 4. The liquid fuel tank 3 stores liquid fuel. The liquid fuel is, for example, liquid hydrogen. The liquid fuel tank 3 has a heat insulation structure that blocks heat transfer from the outside in order to maintain the inside at an extremely low temperature. The outlet of the liquid fuel tank 3 is connected to the inlet of the vaporizer 4 via a liquid fuel flow path 5. A shut-off valve 6 is provided in the liquid fuel flow path 5. The vaporizer 4 is a heat exchanger that vaporizes liquid fuel. The fuel gas formed by the vaporizer 4 vaporizing the liquid fuel is, for example, hydrogen gas.

[0014] Note that the liquid fuel stored in the liquid fuel tank 3 may be another type of liquefied fuel such as a hydrocarbon-based fuel. That is, the fuel gas supplied by the fuel gas supply source 2 may be another type of fuel gas such as a hydrocarbon-based fuel. The fuel gas supply source 2 may be a fuel gas tank that stores fuel gas.

[0015] The outlet of the vaporizer 4 is connected to the fuel injector 23 of the internal combustion engine E via a fuel gas flow path 7. That is, the fuel gas flow path 7 guides the fuel gas from the vaporizer 4 toward the internal combustion engine E. A reciprocating pump 9 that pressurizes the fuel gas in the fuel gas flow path 7 toward the internal combustion engine E is arranged in the fuel gas flow path 7. The reciprocating pump 9 is driven by the driving force of the internal combustion engine E.

[0016] The reciprocating pump 9 includes a compression chamber 72 and a pump piston 56 that defines the compression chamber 72. As the pump piston 56 reciprocates by the driving force of the internal combustion engine E, the fuel gas introduced into the compression chamber 72 through the compression chamber inlet 71 is pressurized, and the pressurized fuel gas is discharged from the compression chamber outlet 73. In the reciprocating pump 9, the pump piston 56 reciprocates by the reciprocating force of the reciprocating structure 58. In the present embodiment, the reciprocating structure 58 converts the rotational force generated by the internal combustion engine E into a reciprocating force and transmits it to the pump piston 56 of the reciprocating pump 9. The detailed structure of the reciprocating pump 9 will be described later.

[0017] A sub-pump 8 is disposed in the fuel gas flow path 7 between the fuel gas supply source 2 and the reciprocating pump 9. Thereby, the pressure of the fuel gas supplied to the reciprocating pump 9 can be increased. In the present embodiment, the sub-pump 8 is a rotary pump. The rotary pump can be, for example, a Roots pump.

[0018] The sub-pump 8 is, for example, a pump driven by the energy of the internal combustion engine E. The sub-pump 8 may be an exhaust pressure-driven pump that is driven using the pressure energy of the exhaust gas of the internal combustion engine E, or a mechanical-driven pump that is driven by the driving force of the internal combustion engine E. The sub-pump 8 may be driven by an electric motor. Note that the sub-pump 8 may be omitted.

[0019] A cooler 10 is disposed downstream of the reciprocating pump 9 in the fuel gas flow path 7. The cooler 10 is a heat exchanger that cools the fuel gas pressurized and heated by the reciprocating pump 9. Since the fuel gas is cooled and its volume is reduced by the cooler 10, the filling efficiency of the fuel gas into the combustion chamber 62 of the internal combustion engine E is improved. Note that the cooler 10 may be disposed at other locations as long as it is downstream of the reciprocating pump 9.

[0020] A first return passage 12, which bypasses the reciprocating pump 9, is connected to the fuel gas passage 7. The first return passage 12 connects the portion of the fuel gas passage 7 downstream of the reciprocating pump 9 to the portion upstream of the reciprocating pump 9. A relief valve 13 is located in the first return passage 12. When the pressure in the portion of the fuel gas passage 7 downstream of the reciprocating pump 9 exceeds a predetermined value, the relief valve 13 opens. Note that the first return passage 12 may be omitted.

[0021] A pressure reducing valve 11 is located downstream of the cooler 10 in the fuel gas passage 7. The presence of the pressure reducing valve 11 ensures that the fuel gas injection pressure into the combustion chamber is maintained within a constant range, regardless of the state of the internal combustion engine E or the fuel gas supply source 2. The fuel gas passage 7 is connected downstream of the pressure reducing valve 11 to the fuel injector 23 of the internal combustion engine E. The fuel injector 23 injects fuel gas into the combustion chamber 62 or intake port of the internal combustion engine E. In this embodiment, the fuel injector 23 directly injects fuel gas into the combustion chamber 62 of the internal combustion engine E. In this embodiment, since fuel injection is performed during the compression stroke with the intake port closed, a high injection pressure is required to overcome the pressure in the combustion chamber 62. For example, an injection pressure of 10 MPa or higher is required.

[0022] When the pressure of the fuel gas downstream of the pressure reducing valve 11 falls below a predetermined pressure, the pressure reducing valve 11 opens and the fuel gas upstream of the pressure reducing valve 11 is directed downstream. When the pressure of the fuel gas downstream of the pressure reducing valve 11 reaches a pressure that can overcome the pressure in the combustion chamber 62 and be directly injected into the combustion chamber 62, the pressure reducing valve 11 closes. A reciprocating pump 9 is provided to prevent a drop in the pressure of the fuel gas upstream of the pressure reducing valve 11 due to this opening operation of the pressure reducing valve 11.

[0023] A surge tank 16 is connected to the portion of the fuel gas passage 7 between the cooler 10 and the pressure reducing valve 11. The connection of the surge tank 16 suppresses pressure fluctuations in the combustion gas upstream of the pressure reducing valve 11. An exhaust passage 17 is connected to the portion of the fuel gas passage 7 between the pressure reducing valve 11 and the internal combustion engine E. A relief valve 18 is located in the exhaust passage 17. If the pressure in the exhaust passage 17 exceeds a predetermined value due to an abnormality or an event such as the internal combustion engine E stopping, the relief valve 18 opens to reduce the pressure in the exhaust passage 17.

[0024] An intake passage 19 is connected to the intake port of the internal combustion engine E, which guides outside air into the combustion chamber. A throttle valve 20 is located in the intake passage 19. The throttle valve 20 is an electronically controlled throttle valve, but it may also be a manual throttle valve that is mechanically linked to the driver's manual operation. In the combustion chamber 62 of the internal combustion engine E, fuel gas supplied from the fuel injector 23 burns together with oxygen in the air supplied from the intake passage 19 through the throttle valve 20. An exhaust passage 21 is connected to the exhaust port of the internal combustion engine E, which discharges exhaust gas from the combustion chamber 62. A starter motor SM is connected to the internal combustion engine E to start it.

[0025] Figure 2 is a block diagram of the controller 25 and other components of the internal combustion engine system 1 shown in Figure 1. As shown in Figure 2, the internal combustion engine system 1 includes a controller 25. The controller 25 controls the shut-off valve 6, throttle valve motor 22, fuel injector 23, spark plug 24, starter motor SM, shut-off valve 6, etc. The controller 25 includes a processing circuit 26. The controller 25 includes, for example, a processor 27, system memory 28, and storage memory 29. The processor 27 may include, for example, a CPU. The system memory 28 may include, for example, volatile memory. The storage memory 29 may include a hard disk, non-volatile memory, or a combination thereof. The storage memory 29 stores program P. An example of the processing circuit 26 is a configuration in which the processor 27 executes program P read from the system memory 28.

[0026] The controller 25 receives detection data from an operation command detection sensor 36 that detects the driver's driving operations, a vehicle state detection sensor 37 that detects the state of the vehicle V, a fuel supply state detection sensor 38 that detects the fuel supply state, and a combustion state detection sensor 39 that detects the state of the internal combustion engine E. The operation command detection sensor 36 detects information related to the driver's driving operations, such as the amount of accelerator operation, brake operation, and starting operation. The vehicle state detection sensor 37 detects information related to the state of the vehicle while it is moving, such as the vehicle's speed, wheel rotation speed, gear ratio, and vehicle posture. The fuel supply state detection sensor 38 detects information related to the fuel supply state, such as the pressure, flow velocity, and temperature of the fuel present in the fuel gas supply source 2 or fuel gas passage 7. The combustion state detection sensor 39 detects information related to the combustion state of the internal combustion engine E, such as the rotation speed of the crankshaft 35, exhaust pressure, and components contained in the exhaust gas.

[0027] The controller 25 controls various actuators 22, 23, 24, SM, 6 based on detection information from various sensors 36 to 39. The controller 25 controls valves, sub-pumps 8, etc., in the fuel supply system based on fuel supply status information detected by the supply status detection sensor 38. For example, if the controller 25 anticipates a future fuel supply shortage based on the combustion state of the internal combustion engine E, the driver's operation commands, etc., it may control the valves and sub-pumps 8 in the fuel supply system to increase the fuel supply. If the controller 25 anticipates a future fuel supply surplus based on the combustion state of the internal combustion engine E, the driver's operation commands, etc., it may control the valves and sub-pumps 8 in the fuel supply system to decrease the fuel supply. The controller 25 also controls the combustion state of the internal combustion engine E based on the combustion state of the internal combustion engine E, the state of the vehicle V, and the driver's operation commands. As described above, the controller 25 may control the fuel injector 23, throttle valve motor 22, and spark plug 24 so that the combustion state of the internal combustion engine E is appropriate.

[0028] Figure 3 is a perspective view of a reciprocating unit 30, which consists of the internal combustion engine E and the reciprocating pump 9 shown in Figure 1. As shown in Figure 3, the reciprocating unit 30 includes the internal combustion engine E and the reciprocating pump 9. The reciprocating unit 30 integrates the internal combustion engine E and the reciprocating pump 9. In this embodiment, the reciprocating unit 30 includes a one-piece common cylinder block 32. The common cylinder block 32 includes four engine cylinders 42 and one pump cylinder 52. The engine cylinder 42 has a portion of the combustion chamber 62 and a reciprocating chamber in which the engine piston 46 reciprocates. The pump cylinder 52 has a portion of the compression chamber 72 and a reciprocating chamber in which the pump piston 56 reciprocates.

[0029] The portion of the common cylinder block 32 corresponding to four engine cylinders 42 functions as an engine cylinder block 41. The portion of the common cylinder block 32 corresponding to one pump cylinder 52 functions as a pump cylinder block 51. In other words, the engine cylinder block 41 and the pump cylinder block 51 are continuous with each other.

[0030] By integrating the engine cylinder block 41 and the pump cylinder block 51 into a single unit, the entire internal combustion engine E and reciprocating pump 9 are made more compact and the number of parts is reduced. During the manufacturing of the reciprocating unit 30, the engine cylinder 42 and the pump cylinder 52 can be formed in a series of processes, making it easier to reduce the number of work steps. The number of cylinders in the internal combustion engine E is set to 4, but it may be 3 or less, or 5 or more. The number of cylinders in the reciprocating pump 9 is set to 1, but it may be 2 or more. For example, the number of engine cylinders 42 is appropriately selected according to the required output. The number of pump cylinders 52 is appropriately selected according to the required compression ratio. For example, by setting the number of pump cylinders 52 to be less than the number of engine cylinders 42, it is possible to achieve both miniaturization of the reciprocating unit 30 and fuel compression.

[0031] The reciprocating unit 30 includes a crankcase 31 to which a common cylinder block 32 is fixed. That is, the common cylinder block 32 is integrated with the engine crankcase 31 by being fixed to the crankcase 31 with fasteners such as bolts. The engine crankcase 31 has a part that houses the engine crankshaft and a part that houses the pump crankshaft. That is, the part that houses the engine crankshaft and the part that houses the pump crankshaft are continuous with each other. Since the internal combustion engine E and the reciprocating pump 9 share the engine crankcase 31, the configuration of the internal combustion engine system 1 is simplified. In this embodiment, the engine crankcase 31 is divided into an upper case and a lower case. In that case, the upper case of the engine crankcase 31 may be a one-piece molded integrally with the common cylinder block 32. The engine crankcase 31 may be divided in directions other than vertical.

[0032] The reciprocating unit 30 includes a common cylinder head 33 fixed to a common cylinder block 32. The common cylinder head 33 is a one-piece unit. The portion of the common cylinder head 33 corresponding to four engine cylinders 42 functions as an engine cylinder head 45. The portion of the common cylinder head 33 corresponding to one pump cylinder 52 functions as a pump cylinder head 55. That is, the engine cylinder head 45 and the pump cylinder head 55 are continuous with each other.

[0033] The engine cylinder head 45 has a part of the combustion chamber 62, an intake port 61 communicating with the combustion chamber 62, and an exhaust port 63 communicating with the combustion chamber 62. An intake passage 19 is connected to the intake port 61 of the internal combustion engine E. The internal combustion engine E has an intake valve that opens and closes the intake port 61 and an exhaust valve that opens and closes the exhaust port 63, and its intake valve and exhaust valve are driven by a valve train mechanism that is linked to the crankshaft 35, which will be described later. The pump cylinder head 55 has a compression chamber 72, a compression chamber inlet 71 communicating with the compression chamber 72, and a compression chamber outlet 73 communicating with the compression chamber 72. The upstream portion 7a of the fuel gas passage 7, which is on the upstream side of the reciprocating pump 9, is connected to the compression chamber inlet 71 of the reciprocating pump 9, and the downstream portion 7b of the fuel gas passage 7, which is on the downstream side of the reciprocating pump 9, is connected to the compression chamber outlet 73 of the reciprocating pump 9.

[0034] Figure 4 is a longitudinal cross-sectional view of the reciprocating unit 30 shown in Figure 3. As shown in Figure 4, the crankcase 31 has a mating surface 31a. In this embodiment, the mating surface 31a is a flat surface perpendicular to the reciprocating direction of the piston. The mating surface 31a may be a surface that includes steps instead of being a flat surface. The common cylinder block 32 is superimposed on the mating surface 31a of the crankcase 31. In other words, the engine cylinder block 41 and the pump cylinder block 51 are integrally joined to the crankcase 31 by fastening members such as bolts while in contact with the mating surface 31a of the crankcase 31. By arranging the mating surfaces of each cylinder block 41, 51 on a common virtual plane, it is easy to standardize the mating surface 31a. For example, when manufacturing the reciprocating unit 30, the mating surfaces of each cylinder block 41, 51 and the mating surfaces 31a of the crankcase 31 corresponding to each cylinder block 41, 51 can be formed by a series of processes, making it easy to reduce the number of work steps.

[0035] Multiple engine cylinders 42 are arranged adjacent to each other in a line along the rotational axis Y of the crankshaft 35. An engine piston 46 is housed in each engine cylinder 42. The engine piston 46 is slidable along the engine cylinder axis X1, which is the axis of the engine cylinder 42. The combustion chamber 62 is defined by the engine piston 46 and the engine cylinder head 45.

[0036] In this embodiment, the pump cylinder 52 is positioned adjacent to one of the multiple engine cylinders 42. Specifically, the pump cylinder 52 is located outside the engine cylinder 42 located at the end of the multiple engine cylinders 42 in the rotational axis direction Y of the crankshaft 35. This arrangement reduces the heat the pump cylinder 52 receives from the engine cylinder block 41 compared to the case where engine cylinders 42 are positioned on both sides of the pump cylinder 52. A pump piston 56 is slidably housed in the pump cylinder 52. The pump piston 56 is slidable along the pump cylinder axis X2, which is the axis of the pump cylinder 52. The compression chamber 72 is defined by the pump piston 56 and the pump cylinder head 55.

[0037] In this embodiment, the bore diameter of the pump cylinder 52 is the same as the bore diameter of the engine cylinder 42. Also in this embodiment, the stroke length of the pump cylinder 52 is the same as the stroke length of the engine cylinder 42. This allows each cylinder 42 and 52 to be formed in a series of processes, making it easier to reduce the number of work steps. By making the bore diameter of the pump cylinder 52 the same as the bore diameter of the engine cylinder 42, it is easier to make the engine piston 42 and the pump piston 52 common. By making the stroke length of the pump cylinder 52 the same as the stroke length of the engine cylinder 42, it is easier to make the engine crankshaft 35A and the pump crankshaft 35B common.

[0038] By making the shape of the pump cylinder 52 closer to that of the engine cylinder 42, the compression chamber 72 can be enlarged more easily, and the compression ratio can be increased compared to a rotary pump. In addition, the bore diameter and stroke length of the pump cylinder 52 can be appropriately selected according to the required compression ratio. For example, either the bore diameter or stroke length of the pump cylinder 52 may be the same as that of the engine cylinder 42, while the other is different. Alternatively, both the bore diameter and stroke length of the pump cylinder 52 may be different from those of the engine cylinder 42. For example, since the pump cylinder 52 requires a different strength than the engine cylinder 42, where explosions occur during the combustion stroke, the bore diameter of the pump cylinder 52 may be larger than that of the engine cylinder. This allows for an even higher compression ratio of the reciprocating pump 9. Furthermore, if there is a strong requirement for miniaturization of the reciprocating unit 30, at least one of the bore diameter and stroke length of the pump cylinder 52 may be smaller than that of the engine cylinder 42.

[0039] The engine crankcase 31 houses the crankshaft 35, engine connecting rods 47 and pump connecting rods 57. The crankshaft 35 includes a supported portion and an offset portion that is radially offset to one side relative to the supported portion. The crankshaft 35 is formed in a so-called crank shape. The engine connecting rods 47 and pump connecting rods 57 are rotatably connected to the offset portion described above. Each connecting rod 47, 57 has pistons 46, 56 linked to the end opposite to the portion linked to the crankshaft 35. As the crankshaft 35 rotates, the pistons 46, 56 reciprocate radially along the crankshaft 35.

[0040] In this embodiment, the crankshaft 35 has a portion that functions as an engine crankshaft 35A and a portion that functions as a pump crankshaft 35B. The crankshaft 35 is a one-piece shaft in which the engine crankshaft 35A and the pump crankshaft 35B are continuous with each other. In this way, the power transmission path from the engine crankshaft 35A to the pump crankshaft 35B can be shortened because the crankshaft 35 is integrally formed in the reciprocating unit 30. The reciprocating unit 30 can be made more compact and the number of parts can be reduced. The support structure of the engine crankshaft 35A also serves as part or all of the support structure of the pump crankshaft 35B, so the support structure can be simplified. The supported portion of the engine crankshaft 35A is formed coaxially with the supported portion of the pump crankshaft 35B. In other words, the crankcase 31 has a structure that supports the engine crankshaft 35A and a structure that supports the pump crankshaft 35B, and the structure that supports the engine crankshaft 35A also serves as the structure that supports the pump crankshaft 35B. This simplifies the support structure.

[0041] The engine connecting rod 47 connects the crankpin 35Aa of the engine crankshaft 35A to the engine piston 46. One end of the crankshaft 35 transmits power to the drive wheels. In this embodiment, the driving force of the crankshaft 35 is transmitted to the drive wheels via the transmission TM. In this embodiment, one end of the crankshaft 35 is mechanically connected to the input shaft of the transmission TM. The crankshaft 35 is driven by the starter motor SM to which it is mechanically connected, thereby providing the crankshaft 35 with the rotational force necessary to start the internal combustion engine E.

[0042] The pump connecting rod 57 connects the crankpin 35Ba of the pump crankshaft 35B to the pump piston 56. The pump crankshaft 35B and the pump connecting rod 57 are an example of a reciprocating structure 60 that converts the rotation of the pump crankshaft 35B into reciprocating motion and transmits it to the pump piston 56.

[0043] Thus, in this embodiment, the pump crankshaft 35B and the pump connecting rod 57, which constitute the reciprocating structure 60, are supported by the engine crankcase 31. This simplifies the structure and makes the overall structure more compact compared to the case where a separate structure is formed to support the reciprocating structure 60. In addition, in this embodiment, by integrating the pump crankshaft 35B and the engine crankshaft 35A, the power transmission path from the engine crankshaft 35A to the pump crankshaft 35B can be simplified, making the system 1 more compact. Furthermore, by integrating the internal combustion engine E and the reciprocating pump 9 into a single reciprocating unit 30, the mounting structure can be standardized compared to the case where the internal combustion engine E and the reciprocating pump 9 are mounted separately in different locations, making mounting and detachment easier.

[0044] In this embodiment, since the reciprocating structure 60 is housed in the engine crankcase 31, there is no need to adopt a structure that covers the reciprocating structure 60 with a separate cover, and the internal combustion engine system 1 is made more compact. For example, by arranging the pump crankshaft 35B inside the engine crankcase 31, the reciprocating structure 60 can be brought closer to the internal combustion engine E compared to when the pump crankshaft 35B is arranged outside the engine crankcase 31. Also, since the pump piston 56 of the reciprocating pump 9 is driven by the pump crankshaft 35B via the pump connecting rod 57, the pump crankshaft 35B can be supported by a bearing, and the reciprocating pump 9 can be driven with less mechanical loss. In addition, since the pump crankshaft 35B is connected to the reciprocating pump 9 by the pump connecting rod 57, the power transmission structure from the pump crankshaft 35B to the reciprocating pump 9 is simplified. Furthermore, a reciprocating structure using a connecting rod makes it easier to increase the compression ratio compared to a reciprocating structure using a cam.

[0045] In this embodiment, a partition plate 83 is arranged in the internal space S of the engine crankcase 31. The partition plate 83 divides the internal space S of the engine crankcase 31 into a first space S1 in which each engine connecting rod 47 is arranged and a space S2 in which the reciprocating structure 60 is arranged. In this embodiment, the partition plate 83 has a bearing function that supports the crankshaft 35. The crankshaft 35 extends from the first space S1 to the second space S2 by passing through a through hole 83a in the partition plate 83. A sealing member 84 is interposed between the through hole 83a of the partition plate 83 and the crankshaft 35. The partition plate 83 prevents blow-by gas leaking from the combustion chamber 62 over the engine piston 46 into the first space S1 from mixing with gas leaking from the compression chamber 72 over the pump piston 56 into the second space S2. Note that the partition plate 83 may be omitted.

[0046] Figure 5 is a cross-sectional view taken along line VV in Figure 4. As shown in Figures 3 to 5, the pump cylinder block 51 overlaps the engine cylinder block 41 when viewed from the direction of rotation axis Y, which is the direction in which the rotation axis Y of the crankshaft 35 extends. When viewed from the direction of rotation axis Y, the outer edge of the pump cylinder block 51 coincides with the outer edge of the engine cylinder block 41. When viewed from the direction of rotation axis Y, the reciprocating pump 9 and the reciprocating structure 60 are located inside the outer edge of the internal combustion engine E. As a result, the entire internal combustion engine E and the reciprocating pump 9 are made more compact when viewed from the direction of rotation axis Y. In this embodiment, when viewed from the direction of rotation axis Y, the engine cylinder axis X1 and the pump cylinder axis X2 coincide. That is, the engine cylinder 42 and the pump cylinder 52 are aligned in a line along the direction of rotation axis Y. This makes it possible to increase the stroke length of the pump cylinder 52 while preventing the reciprocating unit 30 from becoming larger.

[0047] Furthermore, the pump cylinder block 51 may partially overlap the engine cylinder block 41 when viewed from the rotation axis direction Y. That is, the pump cylinder block 51 may be offset from the engine cylinder block 41 around the rotation axis Y. By having at least a portion of the reciprocating pump 9 and the reciprocating structure 60 overlap with the internal combustion engine E, they can be made more compact compared to the case where they do not overlap.

[0048] As shown in Figure 5, the pump cylinder head 55 has a compression chamber 72, a compression chamber inlet 71 communicating with the compression chamber 72, and a compression chamber outlet 73 communicating with the compression chamber 72. The upstream portion 7a of the fuel gas passage 7, located upstream of the reciprocating pump 9, is connected to the compression chamber inlet 71. The downstream portion 7b of the fuel gas passage 7, located downstream of the reciprocating pump 9, is connected to the compression chamber outlet 73.

[0049] An inlet check valve 74 is provided at the compression chamber inlet 71 of the reciprocating pump 9. The inlet check valve 74 allows flow from the upstream portion 7a of the fuel gas flow path 7 toward the compression chamber inlet 71 of the reciprocating pump 9, and prevents backflow from the compression chamber inlet 71 of the reciprocating pump 9 toward the upstream portion 7a of the fuel gas flow path 7.

[0050] An outlet check valve 75 is provided at the compression chamber outlet 73 of the reciprocating pump 9. The outlet check valve 75 allows flow from the downstream portion 7b of the fuel gas passage 7 toward the compression chamber outlet 73 of the reciprocating pump 9, and prevents backflow from the downstream portion 7b of the fuel gas passage 7 toward the compression chamber outlet 73 of the reciprocating pump 9. In addition, intake and exhaust valves that are linked to the rotation of the crankshaft 35, similar to those in an internal combustion engine E, may be used instead of the inlet check valve 74 and the outlet check valve 75.

[0051] The second space S2 of the crankcase 31 is connected to the upstream portion 7a of the fuel gas passage 7 by a second return passage 14. A check valve 15 is located in the second return passage 14. The check valve 15 allows flow from the second space S2 of the crankcase 31 toward the upstream portion 7a of the fuel gas passage 7, and prevents backflow from the upstream portion 7a of the fuel gas passage 7 toward the second space S2 of the crankcase 31. As a result, gas that leaks from the compression chamber 72 over the pump piston 56 into the second space S2 can be resupplied to the compression chamber 72 via the second return passage 14. As described above, the partition plate 83 prevents blow-by gas from entering the second space S2 from the first space S1, thereby allowing fuel gas with reduced exhaust gas contamination to be guided to the upstream portion 7a of the fuel gas passage 7. The second return passage 14 may be connected to a location other than the upstream portion 7a of the fuel gas passage 7. For example, the second return passage 14 may be formed to guide the gas in the engine crankcase 31 to the intake passage 19.

[0052] Figure 6 is a cross-sectional view taken along line VI-VI in Figure 4. As shown in Figure 6, the common cylinder block 32 has an engine cooling passage 43 and a pump cooling passage 53. The engine cooling passage 43 surrounds the entirety of the four engine cylinders 42 from the horizontal direction. The pump cooling passage 53 surrounds the pump cylinder 52 from the horizontal direction. A portion of the engine cooling passage 43 and a portion of the pump cooling passage 53 are interposed between the pump cylinder 52 and the adjacent engine cylinder 42. The adjacent spacing L2 between the pump cylinder 52 and the adjacent engine cylinder 42 is wider than the adjacent spacing L1 between the multiple engine cylinders 42. Note that the adjacent spacing L2 may be the same as the adjacent spacing L1.

[0053] The engine cooling passage 43 and the pump cooling passage 53 constitute a coolant circulation passage 80. The coolant circulation passage 80 is a closed-loop passage through which a coolant, such as cooling water, flows. The coolant pump 81 and the radiator 82 are arranged in series with each other in the coolant circulation passage 80. The engine cooling passage 43 and the pump cooling passage 53 are connected in parallel with each other in the coolant circulation passage 80.

[0054] The coolant discharged by the coolant pump 81 is divided into coolant that flows into the engine cooling passage 43 and coolant that flows into the pump cooling passage 53. The coolant that flows out of the engine cooling passage 43 and the coolant that flows out of the pump cooling passage 53 merge and flow into the radiator 82. The coolant that flows out of the radiator 82 flows into the coolant pump 81. In other words, the coolant that flows out of the engine cooling passage 43 goes to the radiator 82 without going to the pump cooling passage 53. This configuration prevents excessive heat from being transferred from the engine cylinder 42 to the pump cylinder 52.

[0055] The coolant flowing into the pump cooling passage 53 may be set to have a different coolant temperature and volume compared to the coolant flowing into the engine cooling passage 43. The pump cooling passage 53 may be set to have a lower coolant temperature or a higher coolant volume. For example, the portion of the pump cooling passage 53 closer to the engine cylinder 42 may have a larger horizontal cross-sectional area than the remaining portion. This makes it easier to prevent the temperature of the pump cylinder 52 from rising.

[0056] The pump cooling passage 53 may be connected in series with the engine cooling passage 43 and positioned upstream of the engine cooling passage 43. This makes it easier to prevent the temperature around the pump cylinder from rising. The engine cooling passage 43 and the pump cooling passage 53 may be combined. A separate radiator may be provided for the pump cooling passage 53, in addition to the radiator for the engine cooling passage 43.

[0057] Figure 7 is a cross-sectional view of a modified example of Figure 6. As shown in Figure 7, the common cylinder block 32 may have a pump cooling passage 153 in the region between the pump cylinder 52 and the adjacent engine cylinder 42, but without surrounding the pump cylinder 52. For example, the pump cooling passage 153 may be located only in the region between the pump cylinder 52 and the adjacent engine cylinder 42. The common cylinder block 32 may also have a cam chain tunnel 154 in the region between the pump cylinder 52 and the adjacent engine cylinder 42. A cam chain that transmits the driving force of the crankshaft to a valve train, which includes a cam mechanism that drives the intake and exhaust valves of the internal combustion engine E, passes through the cam chain tunnel 154. This helps to suppress the temperature rise of the pump cylinder 52. Note that this cam chain tunnel 154 may also be applied to the configuration of Figure 6.

[0058] (Second Embodiment) Figure 8 is a diagram corresponding to Figure 4 of the reciprocating unit 130 of the internal combustion engine system according to the second embodiment. Figure 9 is a cross-sectional view taken along line IX-IX in Figure 8. Components common to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figures 8 and 7, the reciprocating unit 130 of the second embodiment has a different type of reciprocating structure 160 that converts the rotation of the crankshaft 135 into reciprocating motion and transmits it to the pump piston 56 than that of the first embodiment. The reciprocating structure 160 of the second embodiment has a cam structure. Specifically, the reciprocating structure 160 includes a rod 185, a cam 186, and a spring 187. The reciprocating structure 160 is housed in the crankcase 31.

[0059] The rod 185 extends from the pump piston 56 in a direction away from the compression chamber 72 along the pump cylinder axis X2 and protrudes into the internal space of the crankcase 31. The crankshaft 135 has a portion that functions as the engine crankshaft 35A and a portion that functions as the pump camshaft 135B. The crankshaft 135 is a one-piece shaft in which the engine crankshaft 35A and the pump camshaft 135B are continuous with each other, but it may also be a shaft in which the engine crankshaft 35A and the separate pump camshaft 135B are directly connected to each other. The cam 186 is fixed to the pump camshaft 135B which extends along the rotation axis Y of the crankshaft 135. The cam 186 is provided on the pump camshaft 135B. The cam 186 is eccentric with respect to the rotation axis Y.

[0060] The spring 187 biases the rod 185 toward the cam 186. When the crankshaft 135 rotates, the cam 186 presses against the end face of the rod 185 in the direction that extends the pump cylinder axis X2, causing the rod 185 to reciprocate. The reciprocating motion of the rod 185 causes the pump piston 56 to reciprocate.

[0061] By realizing the reciprocating structure 160 using the cam 186, the reciprocating structure 160 can be made even smaller compared to the case where the reciprocating structure is realized using a connecting rod, making it easier to achieve further overall compactness. In the second embodiment as well, the reciprocating structure 160, consisting of the cam 158, pump camshaft 135B, and rod 185, is supported by the crankcase 31. This simplifies the structure compared to the case where a separate structure is formed to support the reciprocating structure 160, and makes the overall structure more compact.

[0062] The cam 186 may be mounted on a rotating body (for example, a balancer shaft) that rotates in conjunction with the engine crankshaft 35A. In this case as well, the reciprocating structure is supported by the crankcase 31, so the overall structure can be made more compact. Furthermore, by housing the reciprocating structure within the crankcase 31, it is not necessary to adopt a structure that covers the reciprocating structure with a separate cover. Note that the other configurations are the same as those of the first embodiment described above, so their explanation will be omitted.

[0063] (Third embodiment) Figure 10 is a diagram corresponding to Figure 4 of the reciprocating unit 230 of the internal combustion engine system according to the third embodiment. Components common to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 10, in the reciprocating unit 230 of the third embodiment, the pump cylinder block 251 of the reciprocating pump 209 is a separate piece from the engine cylinder block 241 of the internal combustion engine E and is spaced apart from the engine cylinder block 241. That is, there is a gap G between the engine cylinder block 241 and the pump cylinder block 251. This reduces the heat transferred from the engine cylinder 42 to the pump cylinder 52. The gap G between the engine cylinder block 241 and the pump cylinder block 251 may be an air space where no objects exist, but the gap G may be partially or entirely filled with an insulating material 287.

[0064] The engine cylinder block 241 and the pump cylinder block 251 are integrated into the crankcase 31. An insulating material 286 is sandwiched between the pump cylinder block 251 and the crankcase 31. The insulating material 286 may be, for example, glass wool. This reduces the heat transferred from the engine cylinder 42 to the pump cylinder 52 via the crankcase 31. The insulating material 286 may also be applied to other embodiments. An insulating material may also be sandwiched between the engine cylinder block and the crankcase. The other configurations are the same as those of the first embodiment described above, so their description is omitted.

[0065] As a variation, the engine crankcase housing the engine crankshaft 35A and the pump crankcase housing the pump crankshaft 35B may be separate pieces. In this case, the pump cylinder block 251 may be a common piece with the engine cylinder block 241 of the internal combustion engine E, or it may be a separate piece. Even with such a configuration, the reciprocating structure 60 is directly or indirectly supported by the crankcase, which simplifies the structure and makes the overall structure more compact. Furthermore, the cam chain tunnel 154 described above may be located in the portion of the engine cylinder block 241 facing the gap G.

[0066] (Fourth Embodiment) Figure 11 is a perspective view of the reciprocating unit 330 of the internal combustion engine system according to the fourth embodiment. Figure 12 is a cross-sectional view of the reciprocating unit 330 of Figure 11 as seen from the direction of the rotation axis Y. Note that other configurations are the same as those of the first embodiment described above, so their explanation will be omitted. As shown in Figures 11 and 12, the reciprocating unit 330 of the fourth embodiment includes an internal combustion engine E which is a V-type engine. The internal combustion engine E includes a first engine cylinder block 341A connected to the crankcase 31, and a second engine cylinder block 341B connected to the crankcase 31 at a position offset circumferentially from the first engine cylinder block 341A around the rotation axis Y. The first engine cylinder block 341A and the second engine cylinder block 341B are arranged in a V-shape when viewed from the direction of the rotation axis Y.

[0067] The reciprocating unit 330 comprises a first reciprocating pump 309A and a second reciprocating pump 309B. The first reciprocating pump 309A has a first pump cylinder block 351A connected to the crankcase 31. The second reciprocating pump 309B comprises a second pump cylinder block 351B connected to the crankcase 31 at a position offset circumferentially from the first pump cylinder block 351A around the rotation axis Y. The first pump cylinder block 351A and the second pump cylinder block 351B are arranged in a V-shape when viewed from the rotation axis direction Y.

[0068] The first pump cylinder block 351A is adjacent to the first engine cylinder block 341A along the rotational axis direction Y. The first pump cylinder block 351A may form a one-piece common cylinder block with the first engine cylinder block 341A, or it may be a separate piece from the first engine cylinder block 341A.

[0069] The second pump cylinder block 351B is adjacent to the second engine cylinder block 341B along the rotational axis direction Y. The second pump cylinder block 351B may form a one-piece common cylinder block with the second engine cylinder block 341B, or it may be a separate piece from the second engine cylinder block 341B.

[0070] The pump cylinder 52 of the second reciprocating pump 309B is positioned offset circumferentially around the rotational axis direction Y relative to the engine cylinder 42 of the first engine cylinder block 341A. The pump cylinder 52 of the first reciprocating pump 309A is positioned offset circumferentially around the rotational axis direction Y relative to the engine cylinder 42 of the second engine cylinder block 341B. The other configurations are the same as those of the first embodiment described above, so their description is omitted.

[0071] The first reciprocating pump 309A or the second reciprocating pump 309B may be omitted. The first engine cylinder block 341A or the second engine cylinder block 341B may also be omitted. The angle at which each cylinder block 341A, 341B is separated from each other in the circumferential direction when viewed from the rotation axis direction Y may be any angle, and may be L-shaped with a 90-degree gap or opposing type with a 180-degree gap. Thus, various existing layouts can be adopted for the arrangement of the engine cylinder blocks 341A, 341B. Also, the number of engine cylinder blocks 341A, 341B and the number of pump cylinder blocks 341A, 341B may be different from each other. For example, the number of pump cylinders may be less than the number of engine cylinders.

[0072] (Fifth embodiment) Figure 13 is a perspective view of the reciprocating unit 430 of the internal combustion engine system according to the fifth embodiment. Components common to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 13, the reciprocating unit 430 of the fifth embodiment includes an engine cylinder block 441 connected to the crankcase 31 and a pump cylinder block 451 connected to the crankcase 31 at a position offset circumferentially from the engine cylinder block 441 around the rotation axis Y.

[0073] The engine cylinder block 441 and the pump cylinder block 451 are arranged in a V-shape when viewed from the direction of the rotation axis Y. All of the engine cylinders 42 of the internal combustion engine E are positioned offset in the circumferential direction around the rotation axis Y from the pump cylinders 52 of the pump cylinder block 451. That is, there are no engine cylinder blocks adjacent to the pump cylinder block 451 in the direction of the rotation axis Y. As a result, the pump cylinders 52 are less affected by heat from the engine cylinders 42, and the temperature rise of the fuel gas caused by the reciprocating pump 409 is suppressed. Note that the other configurations are the same as those of the first embodiment described above, so their explanation is omitted.

[0074] It should be noted that the technology of this disclosure is not limited to the embodiments described above. For example, the reciprocating structures 60, 160 may be structures directly or indirectly supported by the crankcase 31 and may be located outside the crankcase 31. In this case, a cover structure covering the reciprocating structures 60, 160 may be fixed to the crankcase 31. For example, the end of the crankshaft 35 protruding from the crankcase 31 may be connected to a pump connecting rod 57 located outside the crankcase 31. In a reciprocating unit, if part or all of the reciprocating pump 9 is formed separately from the internal combustion engine E, it is preferable that the reciprocating pump 9 is supported by the internal combustion engine E.

[0075] The engine crankshaft 35A and the pump crankshaft 35B may be separate components. For example, the engine crankshaft 35A and the pump crankshaft 35B may be coupled on the same axis to form the crankshaft 35. The pump crankshaft 35B may be directly connected to the engine crankshaft 35A by a coupling structure such as a spline or flange coupling. Similarly, the engine crankshaft 35A and the pump camshaft 135B may be separate components. For example, the engine crankshaft 35A and the pump camshaft 135B may be coupled on the same axis to form the crankshaft 135. The pump camshaft 135B may be connected to the engine crankshaft 35A by a coupling structure such as a spline or flange coupling.

[0076] Even in this manner, the above-described effects can be obtained by directly or indirectly supporting the pump crankshaft 35B or pump camshaft 135B in the crankcase 31. Preferably, at least a portion of the pump crankshaft 35B or pump camshaft 135B is directly or indirectly supported in the crankcase 31, and it may be supported at both ends or as a cantilever support. In addition, the reciprocating structures 60, 160 may be supported in the crankcase 31 via one or more intermediate members fixed to the crankcase 31.

[0077] The pump crankshaft 35B or pump camshaft 135B may be arranged coaxially with the engine crankshaft 35A, or it may be arranged non-coaxially with the engine crankshaft 35A, for example, parallel to it. In this case, power from the internal combustion engine E may be transmitted from the engine crankshaft 35A to the pump crankshaft 35B or pump camshaft 135B by a power transmission mechanism such as gears or chains. The rotational speed of the pump crankshaft 35B or pump camshaft 135B may be made different from that of the engine crankshaft 35A by a speed-increasing or reduction mechanism including gears, thereby achieving the required compression ratio and miniaturization of the reciprocating unit.

[0078] From the viewpoint of miniaturizing the unit, the power transmission mechanism that transmits power from the engine crankshaft 35A to the pump crankshaft 35B or pump camshaft 135B is preferably housed within the crankcase 31. The reciprocating direction of the engine piston 46 and the reciprocating direction of the pump piston 56 may be in different directions, and the external shape may be suitable for the space of the vehicle V. For example, the reciprocating direction of the pump piston 56 may be parallel to the engine crankshaft 35, and the pump cylinder 52 may be located on the intake port side of the engine cylinder block 41.

[0079] The rotational power from the engine crankshaft 35A may be transmitted to the reciprocating structures 60, 160 via internal combustion engine rotating bodies that rotate in conjunction with the rotation of the crankshaft 35. For example, the internal combustion engine rotating bodies may be gears and shafts housed in the crankcase 31. Specifically, the internal combustion engine rotating bodies may be balancer gears for vibration reduction, balancer shafts, or rotating bodies for valve trains housed in the crankcase. In addition, the internal combustion engine rotating bodies may be starter gears used to start the internal combustion engine, gears that transmit power to a generator, gears that transmit power to a circulation pump that supplies coolant or lubricating oil, or idler gears that transmit power to those gears. If a transmission or clutch is housed in the crankcase, the internal combustion engine rotating bodies may be gears of the transmission or clutch that rotate in conjunction with the crankshaft of the internal combustion engine.

[0080] In addition, at least a portion of the fuel gas passage 7 may include a passage formed in the crankcase 31. The vehicle V may be equipped with an airflow passage that directs the airflow towards the reciprocating pump rather than the internal combustion engine E. In the fuel gas passage 7, another pump for pressurization may be located downstream of the reciprocating pump 9. In the fuel gas passage 7, multiple pumps may be provided upstream or downstream of the reciprocating pump 9. The sub-pump 8 may be an existing pump other than a Roots pump, such as an axial-flow or centrifugal pump that compresses gas by the rotation of a rotor blade. The sub-pump 8 may also be a reciprocating pump. The internal combustion engine system 1 may be mounted or installed in a place other than a vehicle. For example, it may be installed in a power generation facility that generates energy for power generation, or it may be used as a drive source that generates fluid energy by the power of a crankshaft. The reciprocating pump 9 may be a diaphragm-type piston pump, instead of a cylindrical piston. The reciprocating structures 60,160 may include reduction gears, etc.

[0081] As described above, the embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments to create new embodiments. For example, some components or methods in one embodiment may be applied to other embodiments, and some components in an embodiment can be separated from other components in that embodiment and extracted as appropriate. In addition, the components described in the attached drawings and detailed description include not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology.

[0082] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0083] [Aspect] The embodiments described above are specific examples of the following embodiments.

[0084] (Aspect 1) An internal combustion engine comprising a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod, A fuel gas passage connecting the combustion chamber to a fuel gas supply source, A reciprocating pump that includes a compression chamber and a pump piston defining the compression chamber, and pressurizes the fuel gas in the fuel gas passage, A pump crankshaft supported by the engine crankcase and connected to the engine crankshaft, An internal combustion engine system comprising a pump connecting rod that connects the pump piston to the pump crankshaft.

[0085] This configuration simplifies the power transmission path from the engine crankshaft to the reciprocating pump, allowing for a more compact system. Furthermore, pressurizing the fuel gas with a pump piston makes it easier to increase the compression ratio compared to pumps that compress the gas with rotor blades, thus contributing to a more compact system while maintaining a higher compression ratio.

[0086] (Aspect 2) The internal combustion engine system according to embodiment 1, wherein the pump crankshaft and the pump connecting rod are housed in the engine crankcase.

[0087] With this configuration, the pump connecting rod is housed in the engine crankcase, allowing the engine crankshaft and the pump connecting rod to be brought closer together, resulting in a more compact system.

[0088] (Aspect 3) The internal combustion engine further includes an engine cylinder block having an engine cylinder that houses the engine piston, The reciprocating pump further includes a pump cylinder block having a pump cylinder that houses the pump piston, The internal combustion engine system according to embodiment 1 or 2, wherein the pump cylinder block is integrated with the engine cylinder block or the engine crankcase.

[0089] With this configuration, the reciprocating pump is integrated into the crankcase, and since the internal combustion engine is used for the structure that houses the reciprocating pump, the ease of mounting the reciprocating pump can be improved.

[0090] (Aspect 4) The internal combustion engine further includes an engine cylinder block having an engine cylinder that houses the engine piston, The reciprocating pump further includes a pump cylinder block having a pump cylinder that houses the pump piston, An internal combustion engine system according to any one of embodiments 1 to 3, wherein at least a portion of the pump cylinder block overlaps the engine cylinder block when viewed from the direction of the rotation axis of the engine crankshaft.

[0091] With this configuration, the engine cylinder block and the pump cylinder block overlap, allowing for a more compact overall design of the internal combustion engine and reciprocating pump compared to when they are offset from each other.

[0092] (Aspect 5) The aforementioned crankcase has a mating surface, The internal combustion engine system according to embodiment 3 or 4, wherein the pump cylinder block is superimposed on the mating surface of the engine crankcase.

[0093] This configuration allows for a more compact overall design of the internal combustion engine and reciprocating pump, while simplifying the manufacturing of components such as the crankcase.

[0094] (Aspect 6) The internal combustion engine system according to any one of embodiments 3 to 5, wherein the engine cylinder block and the pump cylinder block are continuous with each other and constitute a one-piece common cylinder block.

[0095] This configuration allows for a more compact overall design of the internal combustion engine and reciprocating pump, as well as a reduction in the number of parts, by integrating the engine cylinder block and pump cylinder block into a single unit.

[0096] (Aspect 7) The pump cylinder is positioned adjacent to the engine cylinder, The internal combustion engine system according to embodiment 6, wherein the common cylinder block has a cooling passage between the pump cylinder and the engine cylinder.

[0097] This configuration reduces the heat transferred from the engine cylinder to the pump cylinder.

[0098] (Pattern 8) An internal combustion engine system according to any one of embodiments 3 to 7, wherein at least a portion of the pump cylinder is positioned offset from the engine cylinder in the circumferential direction around the engine crankshaft.

[0099] With this configuration, at least a portion of the pump cylinder is positioned offset from the engine cylinder, so the pump cylinder is less affected by heat from the engine cylinder, and the temperature rise of the fuel gas caused by the pump can be suppressed.

[0100] (Aspect 9) The pump cylinder block is integrated with the engine crankcase, The internal combustion engine system according to any one of embodiments 3 to 8, wherein the engine cylinder block and the pump cylinder block are spaced apart from each other.

[0101] This configuration reduces the heat transferred from the engine cylinder to the pump cylinder.

[0102] (Aspect 10) An internal combustion engine system according to any one of embodiments 3 to 9, further comprising an insulating material sandwiched between the pump cylinder block and either the engine cylinder block or the engine crankcase.

[0103] This configuration reduces the heat transferred from the engine cylinder to the pump cylinder.

[0104] (Aspect 11) An internal combustion engine system according to any one of embodiments 1 to 10, further comprising a cooler located downstream of the reciprocating pump in the fuel gas passage.

[0105] With this configuration, the fuel gas, which has been pressurized and heated by the reciprocating pump, is reduced in volume by cooling, thereby improving the filling efficiency of the fuel gas supplied to the combustion chamber of the internal combustion engine.

[0106] (Aspect 12) An internal combustion engine system according to any one of embodiments 1 to 11, further comprising a sub-pump interposed in the fuel gas flow path between the reciprocating pump and the fuel gas supply source, for pressurizing the fuel gas in the fuel gas flow path.

[0107] This configuration allows for a suitable increase in the pressure of the fuel gas.

[0108] (Aspect 13) An internal combustion engine comprising a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod, A reciprocating pump includes a compression chamber and a pump piston defining the compression chamber, and pressurizes the fuel gas in a fuel gas passage that connects the combustion chamber to a fuel gas supply source. A reciprocating unit comprising a pump reciprocating structure supported by the engine crankcase, which converts the rotation of the engine crankshaft into reciprocating motion and transmits it to the pump piston.

[0109] This configuration simplifies the power transmission structure from the engine crankshaft to the reciprocating pump, allowing for a more compact unit. Furthermore, by pressurizing the fuel gas with a pump piston, it is easier to increase the compression ratio compared to pumps that compress the gas with rotor blades, thus contributing to a more compact system while maintaining a higher compression ratio.

[0110] (Aspect 14) The reciprocating pump structure is housed in the engine crankcase, as described in embodiment 13 of the reciprocating unit.

[0111] With this configuration, the pump reciprocating mechanism is housed in the engine crankcase, allowing the engine crankshaft and the pump reciprocating mechanism to be brought closer together, thus making the system more compact.

[0112] (Aspect 15) A vehicle equipped with an internal combustion engine system according to any one of embodiments 1 to 12, or a reciprocating unit according to embodiment 13 or 14.

[0113] This configuration allows for the installation of a compact internal combustion engine system or reciprocating unit, thereby improving the feasibility of mounting it in vehicles with limited space. [Explanation of symbols]

[0114] 1. Internal Combustion Engine System 2. Fuel gas supply source 7 Fuel gas flow path 8 Sub-pumps 9,209,309A,309B,409 Reciprocating Pumps 10 Cooler 30, 130, 230, 430, 530 Reciprocating Unit 31 Engine crankcase 31a mating surface 32 Common Cylinder Block 35,135 Crankshaft 35A Engine crankshaft 35B Pump Crankshaft 41,241,341A,341B,441 Engine Cylinder Block 42 engine cylinders 43 Engine cooling passages 46 Engine Pistons 47 Engine connecting rod 51,251,351A,351B,451 Pump Cylinder Block 52 Pump Cylinder 53 Pump cooling channel 56 Pump Piston 57 Pump connecting rod 60,160 Reciprocating structure 62 Combustion chamber 72 Compression Chamber 286 Insulation E Internal combustion engine Y rotation axis direction V Vehicles

Claims

1. An internal combustion engine comprising a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod, A fuel gas passage connecting the combustion chamber to a fuel gas supply source, A reciprocating pump that includes a compression chamber and a pump piston defining the compression chamber, and pressurizes the fuel gas in the fuel gas passage, A pump crankshaft supported by the engine crankcase and connected to the engine crankshaft, An internal combustion engine system comprising a pump connecting rod that connects the pump piston to the pump crankshaft.

2. The internal combustion engine system according to claim 1, wherein the pump crankshaft and the pump connecting rod are housed in the engine crankcase.

3. The internal combustion engine further includes an engine cylinder block having an engine cylinder that houses the engine piston, The reciprocating pump further includes a pump cylinder block having a pump cylinder that houses the pump piston, The internal combustion engine system according to claim 1, wherein the pump cylinder block is integrated with the engine cylinder block or the engine crankcase.

4. The internal combustion engine further includes an engine cylinder block having an engine cylinder that houses the engine piston, The reciprocating pump further includes a pump cylinder block having a pump cylinder that houses the pump piston, The internal combustion engine system according to claim 1, wherein at least a portion of the pump cylinder block overlaps the engine cylinder block when viewed from the direction of the rotation axis of the engine crankshaft.

5. The engine crankcase has a mating surface, The internal combustion engine system according to claim 3, wherein the pump cylinder block is superimposed on the mating surface of the engine crankcase.

6. The internal combustion engine system according to claim 3, wherein the engine cylinder block and the pump cylinder block are continuous with each other and constitute a one-piece common cylinder block.

7. The pump cylinder is positioned adjacent to the engine cylinder, The internal combustion engine system according to claim 6, wherein the common cylinder block has a cooling passage between the pump cylinder and the engine cylinder.

8. The internal combustion engine system according to claim 3, wherein at least a portion of the pump cylinder is positioned circumferentially offset from the engine cylinder around the engine crankshaft.

9. The pump cylinder block is integrated with the engine crankcase, The internal combustion engine system according to claim 3, wherein the engine cylinder block and the pump cylinder block are spaced apart from each other.

10. The internal combustion engine system according to claim 3, further comprising an insulating material sandwiched between the pump cylinder block and either the engine cylinder block or the engine crankcase.

11. The internal combustion engine system according to claim 1, further comprising a cooler located downstream of the reciprocating pump in the fuel gas passage.

12. The internal combustion engine system according to claim 1, further comprising a sub-pump interposed in the fuel gas flow path between the reciprocating pump and the fuel gas supply source, for pressurizing the fuel gas in the fuel gas flow path.

13. An internal combustion engine comprising a combustion chamber, an engine piston defining the combustion chamber, an engine crankshaft, an engine connecting rod connecting the engine piston to the engine crankshaft, and an engine crankcase housing the engine crankshaft and the engine connecting rod, A reciprocating pump includes a compression chamber and a pump piston defining the compression chamber, and pressurizes the fuel gas in a fuel gas passage that connects the combustion chamber to a fuel gas supply source. A reciprocating unit comprising a pump reciprocating structure supported by the engine crankcase, which converts the rotation of the engine crankshaft into reciprocating motion and transmits it to the pump piston.

14. The reciprocating pump structure is housed in the engine crankcase, as described in claim 13.

15. A vehicle equipped with an internal combustion engine system according to any one of claims 1 to 12, or a reciprocating unit according to claim 13 or 14.

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