engine

Abstract

This engine (E) is configured so that an engine body (EB) has formed therein an internal passage (32) through which a cooling liquid (W) circulates. The engine comprises a connector (46) which is attached to an inlet (36) of the internal passage (32) and to which an external cooling liquid passage (42) is connected. The connector (46) includes: an outlet-side cooling liquid introduction port (48) into which the cooling liquid (W) which was led out from an outlet (38) of the internal passage (32) flows; a first branch port (64) for leading the cooling liquid (W) to an inlet (36) of a circulation passage (30); and a second branch port (52) for leading the cooling liquid (W) to a radiator (Ra).

Description

engine Related Applications

[0001] This application claims priority to Japanese Patent Application No. 2023-216219, filed December 21, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a liquid-cooled engine that is cooled by a coolant.

[0003] For example, among engines used as a driving source for vehicles, there are liquid-cooled engines that are cooled with a coolant such as water (see, for example, Patent Document 1). In liquid-cooled engines, the coolant circulates, and coolant that is hotter than a specified temperature is supplied to a radiator to dissipate heat, while coolant that is colder than the specified temperature is supplied to a coolant inlet of the engine.

[0004] JP 2009-162084 A

[0005] When a branch is provided at the engine coolant outlet between a passage leading to the radiator and a passage leading to the engine coolant inlet, the coolant inlet also needs to be branched into a passage from the coolant outlet and a passage for the coolant after heat dissipation in the radiator.

[0006] The disclosure of the present application provides an engine with a simplified configuration by consolidating the branching of the coolant into one location.

[0007] The engine of the present disclosure is an engine in which a circulation passage is formed inside the engine body through which coolant circulates, and is equipped with a connector that is attached to the inlet of the circulation passage to connect to an external coolant passage, and the connector has an outlet-side coolant inlet into which coolant discharged from the outlet of the circulation passage flows, a first branch port that discharges the coolant to the inlet of the circulation passage, and a second branch port that discharges the coolant to a radiator.

[0008] According to the engine of the present disclosure, the coolant branches are concentrated in the inlet connector, which simplifies the configuration compared to when inlet and outlet connectors are provided with separate branches.

[0009] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure. In particular, any combination of two or more of the claims is included in the present disclosure.

[0010] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the accompanying claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts. Fig. 1 is a side view showing an engine according to a first embodiment of the present disclosure. Fig. 2 is a front view showing the engine. Fig. 3 is a simplified diagram showing the flow of coolant in the engine. Fig. 4 is a perspective view showing an inlet unit of a circulation passage of the engine. Fig. 5 is a cross-sectional view showing the inlet unit.

[0011] A preferred embodiment of the present disclosure will be described below with reference to Figures 1 to 5. In Figure 1, engine E of this embodiment is a reciprocating engine, and is used, for example, in an airplane with a propeller located at the tip of the fuselage. In this case, engine E is housed within the fuselage, and engine power is transmitted to the propeller. The use of engine E is not limited to this, and it can also be used as a drive source for a ship, or for vehicles such as motorcycles and automobiles.

[0012] In the following description, the "width direction WD" refers to the direction in which the crankshaft 2 of the engine E extends. In the width direction WD, the direction toward the width center is referred to as the "width inner side," and the direction away from the width center is referred to as the "width outer side." The direction in which the piston 3 of the engine E reciprocates is referred to as the "piston reciprocation direction." A direction perpendicular to both the "width direction WD" and the "piston reciprocation direction" is referred to as the "perpendicular direction PD." In this embodiment, the engine E is mounted with the piston reciprocation direction facing the "vertical direction VD," i.e., the "up-down direction VD," and with the width direction WD facing horizontally.

[0013] The engine E of this embodiment is a six-cylinder engine with six cylinders (cylinders 6) aligned in the direction of extension of the crankshaft 2. However, the number of cylinders is not limited to this and may be, for example, four. Furthermore, although the engine E of this embodiment is a gasoline engine, the fuel is not limited to gasoline.

[0014] The engine E has a crankcase 4 that supports a crankshaft 2, a cylinder 6 that protrudes from the crankcase 4 in the reciprocating direction of a piston 3, and a cylinder head 8 that is connected to the protruding end of the cylinder 6. The crankshaft 2 converts the reciprocating motion of the piston 3 into rotational motion. In the following description, in the vertical direction VD (the direction of reciprocating motion of the piston), the direction in which the cylinder 6 protrudes from the crankcase 4 is referred to as "upward," and the opposite side is referred to as "downward."

[0015] The crankcase 4 is divided into two parts, a lower crankcase 4a and an upper crankcase 4b. In this embodiment, the upper crankcase 4b and the cylinder 6 are integrally formed by molding. However, the upper crankcase 4b and the cylinder 6 may be separate bodies. In the following description, the integrated upper crankcase 4b and the cylinder 6 are referred to as a cylinder block 10.

[0016] The engine E further has a head cover 12 connected to the upper end of the cylinder head 8, and an oil pan 14 connected to the lower end of the crankcase 4. The cylinder head 8 and the cylinder head cover 12 form a cam chamber. The oil pan 14 stores oil, which is a type of engine lubricating fluid. The crankcase 4, cylinder 6, cylinder head 8, head cover 12, and oil pan 14 constitute the engine main body EB.

[0017] An intake port 16 opens at one end (right side in FIG. 1) of the cylinder head 8 in the orthogonal direction PD, and an exhaust port 18 opens at the other end (left side in FIG. 1) of the cylinder head 8 in the orthogonal direction PD. In the following description, the intake port side in the orthogonal direction PD will be referred to as the "intake side," and the exhaust port side will be referred to as the "exhaust side."

[0018] The intake port 16 and the exhaust port 18 are passages formed inside the cylinder head 8. The upstream end of the intake port 16 opens to one end side of the cylinder head 8 in the orthogonal direction PD, and the downstream end opens to a combustion chamber 20 inside the cylinder 6. The upstream end of the exhaust port 18 opens to the combustion chamber 20 inside the cylinder 6, and the downstream end opens to the other end side of the cylinder head 8 in the orthogonal direction PD. The intake port 16 and the exhaust port 18 are formed for each cylinder. The intake port 16 introduces outside air as intake air into the combustion chamber 20. The exhaust port 18 guides exhaust gas from the combustion chamber 20.

[0019] External air is supplied as intake air from the intake port 16 to the combustion chamber 20, and fuel is injected into the combustion chamber 20 from the injector 22, forming a mixture of fuel and air. The mixture in the combustion chamber 20 is ignited by the spark plug 26 and burns. Exhaust gas after combustion is discharged to the outside of the engine from the exhaust port 18.

[0020] As shown in Fig. 2, an output shaft 25 is provided at one end of the engine in the width direction WD. In this embodiment, the rotational force of the crankshaft 2 is reduced by a reduction mechanism 28 and transmitted to the output shaft 25. An aircraft propeller, a vehicle wheel, or the like is connected to the output shaft 25 directly or via a power transmission member. In the following description, the side of the engine E outside in the width direction where the output shaft 25 is located is referred to as the output shaft side, and the opposite side is referred to as the anti-output shaft side.

[0021] The engine E of the present disclosure is a liquid-cooled engine, and cooling parts of the engine E are cooled by circulating a coolant through the circulation passage 30. In this embodiment, water is used as the coolant. However, the coolant is not limited to water. In the following description, "upstream" and "downstream" refer to "upstream" and "downstream" in the direction of coolant flow, respectively.

[0022] 3, the coolant circulation passage 30 of the engine E of this embodiment has an internal passage 32 and an external passage 34. The internal passage 32 is a passage formed inside the engine body EB, and is introduced into the engine from an inlet portion 36 and discharged to the outside of the engine via an outlet portion 38. In this embodiment, the internal passage 32 of the circulation passage 30 is formed inside the cylinder 6 and the cylinder head 8.

[0023] The external passage 34 shown in Figure 2 is composed of a pipe arranged outside the engine E, with its upstream end connected to the outlet 38 and its downstream end connected to a connector 46 attached to the inlet 36. In this embodiment, the pipe constituting the external passage 34 is a steel pipe. However, the pipe is not limited to a steel pipe. The upstream end of the external passage 34 is detachably connected to the outlet 38 via a connector 39 by a fastening member 37 such as a bolt.

[0024] In this embodiment, the inlet 36 of the circulation passage 30 is formed on a mounting surface Su of the engine body EB that faces the orthogonal direction PD. Specifically, the inlet 36 is formed on the intake-side wall surface Su of the cylinder block 10 in the orthogonal direction PD. More specifically, the inlet 36 is formed in a middle portion of the intake-side wall surface of the cylinder block 10 in the engine width direction WD.

[0025] On the other hand, the outlet portion 38 of the circulation passage 30 is formed on a surface of the engine body EB facing the width direction WD. Specifically, the outlet portion 38 is formed at an end of the cylinder head 8 in the engine width direction WD. More specifically, the outlet portion 38 is provided at an end of the cylinder head 8 on the output shaft side in the engine width direction WD. The outlet portion 38 is also disposed above the reduction mechanism 28. Specifically, the outlet portion 38 is disposed at a position overlapping with the reduction mechanism 28 in the up-down direction VD. This allows the outlet portion 38 to be efficiently disposed in the available space above the reduction mechanism 28 and outside the cylinder head 8 in the engine width direction WD, thereby preventing the device from becoming larger.

[0026] A thermostat 40 (FIG. 4) is provided downstream of the external passage 34. The thermostat 40 detects the temperature of the coolant circulating through the engine E, and when the coolant is low, returns it from the inlet 36 to the internal passage 32, and when the coolant temperature rises, sends it to the radiator circulation passage 42. The coolant that has dissipated heat in the radiator Ra (FIG. 3) is returned to the inlet 36 from the radiator circulation passage 42 and supplied to the internal passage 32. In other words, the thermostat 40 adjusts the temperature of the coolant.

[0027] The radiator circulation passage 42 has a primary passage 42a extending from the thermostat 40 to the radiator Ra (FIG. 3) and a secondary passage 42b extending from the radiator Ra to the inlet 36. The radiator circulation passage 42 is formed of, for example, a steel pipe. However, the radiator circulation passage 42 is not limited to a steel pipe.

[0028] A coolant pump 44 is provided in the secondary-side passage 42b. The coolant pump 44 is also provided on a mounting surface Su of the engine body EB facing the orthogonal direction PD. More specifically, the coolant pump 44 is provided on the mounting surface Su of the engine body EB on the intake side in the orthogonal direction PD. The coolant pump 44 pressurizes the coolant in the secondary-side passage 42b. In other words, the secondary-side passage 42b constitutes a coolant passage through which the coolant W pressure-fed by the coolant pump 44 flows. In this embodiment, the secondary-side passage 42b is made of a steel pipe. However, the secondary-side passage 42b is not limited to a steel pipe.

[0029] The coolant pump 44 of this embodiment is driven by the rotational force of the crankshaft 2. More specifically, the rotational force of the crankshaft 2 is transmitted to the coolant pump 44 via a drive chain 47. However, the power transmission means is not limited to the drive chain 47.

[0030] A connector 46 is attached to the inlet 36 of the circulation passage 30. The connector 46 has an opening 69 (FIG. 4) that communicates with the inlet 36 of the circulation passage 30 when attached to the engine body EB.

[0031] In this embodiment, the connector 46 constitutes the inlet unit UN. The inlet unit UN is detachably attached to the cylinder block 10 and houses the thermostat 40 therein, eliminating the need for a separate thermostat case and reducing the number of parts. However, the thermostat 40 may be provided in a thermostat case that is separate from the inlet unit UN. The external passage 34 and the primary passage 42a and secondary passage 42b of the radiator circulation passage 42 are connected to the inlet unit UN.

[0032] 4, the inlet unit UN has an outlet-side coolant inlet 48 to which the external passage 34 is connected. In this embodiment, the piping that constitutes the external passage 34 is inserted into the outlet-side coolant inlet 48 via an elastic member such as an O-ring. The coolant W that is led out from the outlet 38 of the circulation passage 30 flows into the outlet-side coolant inlet 48.

[0033] The inlet unit UN further has a primary passage connection portion 52 (FIG. 2) to which the primary passage 42a of the radiator circulation passage 42 is connected, and a coolant passage connection port 53 to which the secondary passage 42b of the radiator circulation passage 42 is connected. In this embodiment, the downstream end of the pipe that forms the secondary passage 42b is inserted into the coolant passage connection port 53 via an elastic member such as an O-ring.

[0034] 2, the upstream end of the pipe that constitutes the passage between the coolant pump 44 and the connector 46 is inserted into the outlet 44o of the coolant pump 44 via an elastic member such as an O-ring. Also, the downstream end of the pipe that constitutes the passage between the radiator Ra (FIG. 3) and the coolant pump 44 is inserted into the inlet 44i of the coolant pump 44 via an elastic member such as an O-ring. Similarly, the pipe that constitutes the primary passage 42a is inserted into the primary passage connection portion 52 via an elastic member such as an O-ring.

[0035] As shown in FIG. 3, the thermostat 40 switches whether or not the coolant W is led to the radiator Ra depending on the temperature of the coolant W led out from the outlet-side coolant inlet 48 .

[0036] In other words, the thermostat 40 switches whether or not to discharge the coolant W to the radiator Ra depending on the temperature of the coolant W discharged from the outlet 38 of the circulation passage 30. In this embodiment, the primary-side passage connection portion 52 constitutes a second branch port that discharges the coolant W to the radiator Ra.

[0037] 5, the inlet unit UN has therein a partition wall 55. The partition wall 55 divides the internal space of the inlet unit UN, and is configured to prevent the coolant W1 introduced from the outlet 38 via the external passage 34 and the coolant W2 flowing in from the secondary passage 42b of the radiator circulation passage 42 from mixing.

[0038] As shown in Figure 4, the valve 40a of the thermostat 40 is installed between the external passage 34 and the primary passage 42a of the radiator circulation passage 42. When the coolant temperature is low, the valve 40a is closed, and the coolant W from the external passage 34 flows from the bypass passage connection port 64 through the secondary passage 42b toward the inlet 36 of the circulation passage 30. In other words, the bypass passage connection port 64 forms a first branch port that directs the coolant W to the inlet 36 of the circulation passage 30. As the temperature of the coolant rises, the valve 40a opens little by little, and the coolant begins to flow into the primary passage 42a of the radiator circulation passage 42 that is connected to the primary passage connection port 52.

[0039] As shown in Fig. 2, the oil cooler 60 is provided on a mounting surface Su of the engine body EB, which faces the orthogonal direction PD. Specifically, the oil cooler 60 is provided on a wall surface Su on the intake side of the cylinder block 10 in the orthogonal direction PD. The oil cooler 60 cools the lubricating liquid of the engine by heat exchange. In this embodiment, the oil cooler 60 cools the lubricating liquid of the engine by heat exchange with the coolant.

[0040] The oil cooler 60 has a coolant inlet 60a through which the coolant W is introduced and a coolant outlet 60b through which the coolant W is discharged after heat exchange. In this embodiment, the coolant W is supplied to the oil cooler 60 from the connector 46 via a bypass passage 62. The bypass passage 62 has a primary side passage 62a, one end of which is connected to the coolant inlet 60a of the oil cooler 60, and a secondary side passage 62b, one end of which is connected to the coolant outlet 60b of the oil cooler 60.

[0041] The other end of the primary passage 62a of the bypass passage 62 is connected to the connector 46, and the other end of the secondary passage 62b is connected to the cooling pump 44. That is, the connector 46 and the oil cooler 60 are connected via the primary passage 62a of the bypass passage 62, and the oil cooler 60 and the coolant pump 44 are connected via the secondary passage 62b. In this embodiment, the piping that constitutes the bypass passage 62 is made of rubber tubing. However, the piping that constitutes the bypass passage 62 is not limited to rubber tubing and may be, for example, steel piping.

[0042] 4, the connector 46 has a bypass passage connection port 64 to which the primary passage 62a of the bypass passage 62 is connected. The bypass passage connection port 64 opens to the outlet-side coolant inlet port 48 side in the internal space of the inlet unit UN partitioned by the partition wall 55. In other words, the bypass passage connection port 64 is supplied with the coolant W1 flowing in from the external passage 34.

[0043] Next, the flow of the coolant W in the engine E of this embodiment will be described with reference to Figure 3. When the engine E starts, the coolant pump 44 starts in conjunction with this. When the coolant pump 44 starts, the coolant W in the secondary passage 42b of the radiator circulation passage 42 is pressurized and pressure-fed to the connector 46.

[0044] The coolant W flowing into the connector 46 from the coolant passage connection port 53 is supplied from the opening 69 of the connector 46 through the inlet 36 of the circulation passage 30 to the internal passage 32 inside the engine body EB.

[0045] The coolant W that has flowed into the internal passage 32 flows through the internal passage 32 to cool the cooled parts of the engine E, and then flows out from the outlet portion 38 into the external passage 34 outside the engine body EB. The coolant W that has flowed into the external passage 34 flows into the connector 46 from the outlet-side coolant inlet 48.

[0046] The temperature of the coolant W that has flowed into the connector 46 from the outlet-side coolant inlet 48 is detected by the thermostat 40. When the coolant W is low in temperature, the coolant W is returned from the inlet 36 to the internal passage 32 via the bypass passage 62 and the secondary passage 42b through the bypass passage connection port 64, which is a first branch port.

[0047] When the temperature of the coolant W rises, the coolant W is sent from the primary-side passage connection portion 52, which is the second branch port, to the primary-side passage 42a of the radiator circulation passage 42. The coolant W that flows through the primary-side passage 42a of the radiator circulation passage 42 flows into the radiator Ra. The coolant W that has dissipated heat in the radiator Ra is returned to the coolant pump 44 through the secondary-side passage 42b of the radiator circulation passage 42. Thereafter, the same operation is repeated.

[0048] According to the above configuration, the branches of the coolant W are concentrated at the inlet-side connector 46 shown in Fig. 2. Specifically, the coolant W that flows into the connector 46 from the coolant passage connection port 53 is led out to the opening 69, and the coolant W that flows into the connector 46 from the outlet-side coolant inlet port 48 is branched to the bypass passage connection port 64 or the primary-side passage connection part 52. This allows the inlet-side connector and the outlet-side connector to be combined into one, simplifying the configuration.

[0049] In this embodiment, the thermostat 40 is disposed inside the connector 46. In other words, the connector 46 also serves as a thermo-case that houses the thermostat 40. This configuration eliminates the need for a separate thermo-case, thereby reducing the number of parts.

[0050] In this embodiment, the inlet 36 of the circulation passage 30 is formed on the mounting surface Su of the engine body EB facing the orthogonal direction PD, and the outlet 38 of the circulation passage 30 is formed on the surface facing the engine width direction WD. With this configuration, the outlet 38 of the circulation passage 30 is formed on the surface of the cylinder head 8 facing the engine width direction WD, so that a smooth flow of the coolant W can be created from one side to the other in the width direction WD. This makes it possible to effectively cool the areas around the spark plugs 26 lined up in the width direction, for example.

[0051] Because the inlet 36 of the circulation passage 30 is formed on the intake-side mounting surface Su of the engine body EB, the coolant W before entering the internal passage 32 is less susceptible to the high temperature on the exhaust side. However, the inlet 36 may be provided on the exhaust-side wall surface. Furthermore, the inlet 36 is provided in the center of the mounting surface Su, which faces the orthogonal direction PD, in the engine width direction WD. This allows the external passage 34 between the inlet 36 and the outlet 38 on the end face of the engine in the width direction WD to be shortened. As a result, the external passage 34 can be constructed of a steel pipe, eliminating the need for supporting the steel pipe. In particular, steel pipes are preferred for aircraft engines due to their fire resistance and resistance to deformation during altitude ascent.

[0052] In this embodiment, the coolant pump 44 is provided on the same mounting surface Su as the inlet portion 36. This configuration allows the coolant pump 44 to be disposed close to the inlet-side connector 46, thereby enabling the secondary passage 42b between the coolant pump 44 and the connector 46 to be made compact. As a result, the piping of the coolant passage can be shortened and support for the piping can be omitted. Furthermore, the secondary passage 42b between the coolant pump 44 and the connector 46 can be easily constructed of steel pipes. Furthermore, the primary passage connection portion 52, to which the primary passage 42a of the radiator circulation passage 42 is connected, and the coolant passage connection port 53, to which the secondary passage 42b is connected, are provided on the same plane Su, which facilitates the installation of piping leading to and from the radiator Ra.

[0053] In this embodiment, the oil cooler 60 is provided on the same mounting surface Su as the inlet portion 36. With this configuration, the oil cooler 60 can be disposed close to the inlet-side connector 46, and the bypass passage 62 that returns the coolant from the connector 46 through the oil cooler 60 to the coolant pump 44 can be made compact. As a result, the piping of the bypass passage 62 can be shortened and support for the piping can be omitted.

[0054] The present disclosure is not limited to the above embodiments, and various additions, modifications, or deletions are possible without departing from the spirit and scope of the present disclosure. For example, the engine E of the above embodiment can also be applied to saddle-type vehicles such as motorcycles, tricycles, and four-wheeled buggies (all-terrain vehicles). The engine E may be used in an outboard motor or as a propulsion source for aircraft. Additionally, the engine E may be used as a propulsion source for four-wheeled vehicles or small personal watercraft. The number of cylinders is not limited to six, and may be less than six, or seven or more. The engine E may be provided with a supercharger such as a turbocharger or a supercharger. Therefore, such configurations are also included within the scope of the present disclosure.

[0055] 30 Circulation passage 32 Internal passage 36 Inlet portion (inlet of internal passage) 38 Outlet portion (outlet of internal passage) 40 Thermostat 42b Secondary side passage 44 Coolant pump 46 Connector 48 Outlet side coolant inlet 52 Primary side passage connection portion (second branch port) 53 Coolant passage connection port 60 Oil cooler 62 Bypass passage 64 Bypass passage connection port (first branch port) E Engine EB Engine body Su Mounting surface

Claims

1. An engine having a circulation passage formed inside the engine body through which a coolant circulates, and a connector attached to the inlet of the circulation passage to connect an external coolant passage, the connector having an outlet side coolant inlet into which coolant discharged from the outlet of the circulation passage flows in, a first branch port which discharges the coolant to the inlet of the circulation passage, and a second branch port which discharges the coolant to a radiator.

2. An engine as described in claim 1, further comprising a thermostat for adjusting the temperature of the coolant discharged from the outlet of the circulation passage, the thermostat being configured to be able to switch between opening and closing the second branch port based on the temperature of the coolant discharged from the outlet of the circulation passage, and the thermo case being disposed inside the connector.

3. An engine as claimed in claim 1 or 2, wherein the inlet of said circulation passage is formed on a mounting surface facing a direction perpendicular to both the reciprocating direction of the pistons and the width direction of the engine along which the crankshaft extends.

4. An engine as claimed in claim 3, further comprising a coolant pump provided on said mounting surface for pumping engine coolant to said coolant passage.

5. An engine as claimed in claim 3 or 4, wherein an oil cooler for cooling the lubricating liquid of the engine is provided on said mounting surface.

6. An engine according to claim 5, further comprising a bypass passage for returning the coolant from said first branch port to said coolant pump via said oil cooler.

7. An engine according to any one of claims 1 to 6, wherein the connector has a coolant passage connection port to which the coolant passage is connected.

Images