Engine

Abstract

To provide a water-cooling V type engine which enables efficient warming-up.SOLUTION: An engine includes: a first cylinder part 12F having a first cylinder head 12Fb and a first cylinder block 12Fa; a second cylinder part 12R having a second cylinder head 12Rb and a second cylinder block 12Ra; and a water pump 44 which pumps a coolant. The engine includes a coolant circulation passage in which the coolant sent from the water pump 44 circulates through the first cylinder block 12Fa, the second cylinder block 12Ra, the second cylinder head 12Rb, and the first cylinder head 12Fb in a written order.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an engine. [Background technology]

[0002] Conventionally, there is known a water-cooled V-type engine equipped with two cylinder sections consisting of a front bank and a rear bank, and a water pump (see, for example, Patent Document 1). In Patent Document 1, the water-cooled V-type engine branches the cooling water discharged from the water pump and flows it independently to each cylinder section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-215168 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which cooling water flows independently through each cylinder section, as in Patent Document 1, temperature variations are likely to occur between the cylinder sections, and in order to accurately grasp the temperature of each cylinder section, a temperature sensor is required for each cylinder section, which would require, for example, two temperature sensors. The present invention has been made in view of the above circumstances, and has an object to provide a water-cooled V-type engine that can be warmed up efficiently. [Means for solving the problem]

[0005] In order to achieve the above object, a water-cooled V-type engine is provided which includes a first cylinder section having a first cylinder head and a first cylinder block, a second cylinder section having a second cylinder head and a second cylinder block, and a water pump that pumps cooling water, and which is provided with a cooling water circulation passage through which the cooling water pumped out from the water pump circulates in the following order: first cylinder block, second cylinder block, second cylinder head, and first cylinder head. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a water-cooled V-type engine that can be warmed up efficiently. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. [Figure 2] FIG. 2 is a diagram showing a circulation path of coolant in the engine. [Figure 3] Schematic diagram showing the pipe arrangement for a four-cylinder engine. [Figure 4] Schematic diagram showing the pipe arrangement for a two-cylinder engine. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side cross-sectional view of an engine 1 according to an embodiment of the present invention. The engine 1 is a water-cooled V-type engine mounted on a motorcycle, and can also be called an internal combustion engine and a power unit. The engine 1 includes a crankcase 11 that rotatably supports a crankshaft 10, a first cylinder section 12F that constitutes front cylinders (also referred to as a first bank) that extend forward and upward from the top of the crankcase 11, and a second cylinder section 12R that constitutes rear cylinders (also referred to as a second bank) that extend rearward and upward from the top of the crankcase 11. This embodiment shows an engine 1 for a motorcycle in which the first cylinder section 12F is located on the front side and the second cylinder section 12R is located on the rear side. That is, the axial direction of the crankshaft 10 is the left-right direction of the motorcycle, and the engine is horizontally mounted in which the first cylinder 12F and the second cylinder section 12R are aligned in a front-to-rear direction. The axial direction of the crankshaft 10 corresponds to the crankshaft direction of the present disclosure.

[0009] The first cylinder section 12F includes a first cylinder block 12Fa, a first cylinder head 12Fb connected to the top surface of the first cylinder block 12Fa, and a first head cover 12Fc that covers the top surface of the first cylinder head 12Fb. The second cylinder section 12R includes a second cylinder block 12Ra, a second cylinder head 12Rb connected to the top surface of the second cylinder block 12Ra, and a second head cover 12Rc that covers the top surface of the second cylinder head 12Rb.

[0010] Each of the cylinder blocks 12Fa and 12Ra has a cylinder bore 15 formed therein, and a piston 16 is provided in the cylinder bore 15. The piston 16 is connected to the crankshaft 10 via a connecting rod 17. Each cylinder head 12Fb, 12Rb is formed with an intake port 18a and an exhaust port 18b, and is provided with an intake valve 19a and an exhaust valve 19b that open and close the ports 18a, 18b. A valve mechanism 20 that drives the valves 19a, 19b is provided between each cylinder head 12Fb, 12Rb and each head cover 12Fc, 12Rc.

[0011] In this description, unless otherwise specified, directions such as front, rear, left, right, and up and down are directions based on the engine 1 and coincide with directions based on the motorcycle on which the engine 1 is mounted. In each drawing, the symbol FR indicates the front of the engine 1, the symbol UP indicates the top of the engine 1, and the symbol LH indicates the left of the engine 1.

[0012] The crankcase 11 is formed as a hollow case that is divided by a partition wall 11c into a sealed crank chamber 11a that houses the main parts of the crankshaft 10 (such as the crank web 10c) and a transmission chamber 11b that houses the transmission 21. The crankcase 11 of this embodiment is divided into left and right halves, and an oil pan 22 is formed integrally with the lower part of the crankcase 11. The oil pan 22 functions as an oil reservoir that stores oil that lubricates each part of the engine 1. The crankshaft 10 is rotatably supported in the crankcase 11 along the left-right direction (corresponding to the vehicle width direction) of the engine 1. The transmission chamber 11b is formed in the rear of the crankcase 11 (the area behind the sealed crankcase 11a). A main shaft 31 and a counter shaft 32, which are rotatably supported in the crankcase 11, are provided in the transmission chamber 11b.

[0013] Gear sets 31a, 32a, etc. provided on main shaft 31 and counter shaft 32 constitute transmission 21 that transmits the rotation of crankshaft 10 to counter shaft 32 at multiple speed ratios. Main shaft 31 and counter shaft 32 are arranged parallel to crankshaft 10. Counter shaft 32 functions as the output shaft of engine 1 and drives rear wheels, which are drive wheels, via a power transmission mechanism (for example, a chain transmission mechanism).

[0014] A feed pump 41 is disposed below the crankcase 11, above the oil pan 22, and draws oil from the oil pan 22 through the oil strainer 23 and passes it through oil passages to lubricate various parts of the engine. The feed pump 41 includes an inner rotor 41b and an outer rotor 41c that form a feed pump rotor 41a, and the inner rotor 41b rotates integrally with the pump shaft 42, thereby drawing oil from the oil pan 22 and supplying it to parts of the engine that need to be lubricated. The pump shaft 42 is disposed parallel to the crankshaft 10 and is rotatably supported by the crankcase 11. The feed pump 41 is an example of a lubricating oil pump, and the feed pump rotor 41a is an example of an oil pump rotor.

[0015] A water pump 44 is supported on the right front portion of the crankcase 11. The water pump 44 is driven by the rotation of the crankshaft 10 and pumps coolant, thereby shortening the power transmission path between the water pump 44 and the crankshaft 10.

[0016] [Cooling water circulation passage configuration] 2 is a diagram showing the circulation path of the cooling water in the engine 1. The first cylinder block 12Fa, the first cylinder head 12Fb, the second cylinder block 12Ra, and the second cylinder head 12Rb are provided with cooling water passages 13Fa, 13Fb, 13Ra, and 13Rb, respectively, through which the cooling water flows.

[0017] The coolant passage 13Fa of the first cylinder block 12Fa and the coolant passage 13Ra of the second cylinder block 12Ra are connected by a first pipe 45. As shown in FIG. 1, the first pipe 45 is a pipe member that connects the upper back surface of the first cylinder block 12Fa and the upper front surface of the second cylinder block 12Ra. In a V-type engine 1, the upper back surface of the first cylinder block 12Fa and the upper front surface of the second cylinder block 12Ra are close to each other, so the overall length of the first pipe 45 can be shortened. Furthermore, using a straight pipe member for the first pipe 45 makes it easier to ensure space for arranging the first pipe 45 and is advantageous for shortening the coolant passage.

[0018] As shown in FIG. 2, the coolant passages 13Fb of the first cylinder head 12Fb and the coolant passages 13Rb of the second cylinder head 12Rb are connected by a second pipe 46. As shown in FIG. 1, the second pipe 46, like the first pipe 45, is a pipe member that connects the upper rear surface of the first cylinder block 12Fa and the upper front surface of the second cylinder block 12Ra. In the side view of the engine shown in FIG. 1, the second pipe 46 is higher than the first pipe 45 and extends in the front-to-rear direction parallel to the first pipe 45. This allows the first pipe 45 and the second pipe 46 to be arranged compactly, which is also advantageous for shortening the coolant passages.

[0019] The first pipe 45 and the second pipe 46 are arranged offset vertically in a side view of the engine 1 (corresponding to a view in the axial direction of the crankshaft 10). This allows workers assembling and maintaining the engine 1 to easily access the first pipe 45 and the second pipe 46, improving the ease of assembly and maintenance of the engine 1. The first pipe 45 and the second pipe 46 are also arranged offset in the left-right direction of the engine 1. For example, the first pipe 45 is arranged on one of the left and right sides (left side) of the engine 1, and the second pipe 46 is arranged in the left-right center of the engine 1 or its vicinity. In other words, the first pipe 45 is arranged offset to one side with respect to the center of the first cylinder block 12Fa in the axial direction of the crankshaft 10, and the second pipe 46 is arranged in the center of the first cylinder block 12Fa in the crankshaft direction or its vicinity. This also allows workers to easily access the first pipe 45 and the second pipe 46, improving the ease of assembly and maintenance of the engine 1.

[0020] As shown in FIG. 1, a thermostat case 47 is disposed around the exhaust port 18b of the first cylinder head 12Fb. In this embodiment, the thermostat case 47 is disposed below the exhaust port 18b. The coolant passage 13Fb of the first cylinder head 12Fb is connected to the thermostat case 47, and the coolant that has passed through the engine 1 flows into the thermostat case 47. A thermostat 47a is provided inside the thermostat case 47. Depending on the temperature of the coolant that has passed through the engine 1, the thermostat 47a switches the output destination of the coolant between a path connected to the water pump 44 and a path that passes through the radiator 48.

[0021] The radiator 48 is disposed in the upper front portion of the engine 1 or in its vicinity, in other words, in the upper front portion of the first cylinder portion 12F or in its vicinity. The radiator 48 cools the cooling water sent to the radiator 48 by natural wind such as wind generated by running.

[0022] When the temperature of the coolant is in the low temperature range, that is, when the thermostat 47a selects a route that returns the coolant that has passed through the engine 1 to the water pump 44 without passing through the radiator 48, the coolant circulates by flowing from the water pump 44 to the coolant passage 13Fa in the first cylinder block 12Fa, the first pipe 45, the coolant passage 13Ra in the second cylinder block 12Ra, the coolant passage 13Rb in the second cylinder head 12Rb, the second pipe 46, the coolant passage 13Fb in the first cylinder head 12Fb, the thermostat 47a, and the water pump 44 in that order. In other words, this engine 1 is configured so that the coolant flows through a single route that includes the first cylinder portion 12F and the second cylinder portion 12R, rather than flowing independently to each of the first cylinder portion 12F and the second cylinder portion 12R. In this case, the cooling water that exchanges heat with each part of the engine 1 circulates through a single path within the engine 1, so the amount of cooling water required can be reduced and the engine 1 can be warmed up efficiently.

[0023] When the temperature of the coolant is in the high temperature range, that is, when the thermostat 47a selects a route in which the coolant that has passed through the engine 1 passes through the radiator 48, the coolant flows from the water pump 44 to the thermostat 47a through the same passage as described above. The coolant that reaches the thermostat 47a passes through the radiator 48 and then flows to the water pump 44. In this case, the coolant flows through a single route that includes the first cylinder portion 12F, the second cylinder portion 12R, and the radiator 48. Because the coolant passes through the radiator 48, it can be cooled, making it easier to maintain the engine 1 within the appropriate temperature range.

[0024] When cooling the engine 1, if the cooling water passage is branched and cooling water flows independently to each of the first cylinder section 12F and the second cylinder section 12R, temperature variations are likely to occur between the first cylinder section 12F and the second cylinder section 12R, and multiple thermostats 47a are required to accurately grasp the temperatures of the first cylinder section 12F and the second cylinder section 12R.

[0025] In contrast, in the present embodiment, the cooling water circulation passage is a single path including the first cylinder section 12F and the second cylinder section 12R, thereby suppressing temperature variations between the first cylinder section 12F and the second cylinder section 12R and reducing the amount of cooling water required. This suppresses temperature variations between the first cylinder section 12F and the second cylinder section 12R during warm-up of the engine 1, allowing each section to reach an appropriate temperature and achieving rapid warm-up. As a result, the warm-up time can be shortened. Furthermore, it becomes easier to appropriately control the temperature of the engine 1 during warm-up or when using the radiator 48. Furthermore, since the cooling water circulation passage is unified, the cooling water circulation passage is simplified and there is no need to install multiple thermostats 47a. This improves the ease of assembly and maintenance of the engine 1 and reduces the number of parts.

[0026] Note that a portion of the cooling water circulation passage may branch off. For example, the cooling water circulation passage may be divided into multiple passages at any of the water pump 44, the cooling water passage 13Fa in the first cylinder block 12Fa, the first pipe 45, the cooling water passage 13Ra in the second cylinder block 12Ra, the cooling water passage 13Fb in the second cylinder head 12Rb, the second pipe 46, and the cooling water passage 13Fb in the first cylinder head 12Fb.

[0027] In this embodiment, the thermostat 47a is located downstream of the first cylinder head 12Fb in the coolant circulation passage, which allows the flow of coolant to be controlled at the point where the coolant temperature is highest, making it suitable for accurate temperature management of the engine 1.

[0028] As described above, the water pump 44 is driven by the rotation of the crankshaft 10 and is disposed on the front right side of the crankcase 11. This allows the water pump 44 to be disposed close to the crankshaft 10 and the first cylinder block 12Fa. This makes it possible to shorten the power transmission path between the water pump 44 and the crankshaft 10 and the cooling water passage between the water pump 44 and the first cylinder block 12Fa, thereby enabling efficient supply of cooling water.

[0029] By shortening the coolant passage, the piping length of the coolant circulation passage can be shortened, so that the water pump 44 can circulate the coolant with less pressure. In other words, the pressure-feeding efficiency of the water pump 44 can be improved. This allows the coolant to circulate efficiently within the engine 1, and allows for efficient warm-up and other operations.

[0030] Next, the relationship between the first pipe 45, the second pipe 46, and the stud bolts 50 provided on the front and rear cylinder portions 12F, 12R will be described. 3 and 4 are diagrams showing the positional relationship between the first pipe 45, the second pipe 46, and the cylinder sections 12F, 12R. Fig. 3 shows an example of an engine 1 having four cylinders, two at the front and two at the rear. Fig. 4 shows an example of an engine 1 having two cylinders.

[0031] As shown in Figures 3 and 4, stud bolts 50 are arranged at intervals in the first cylinder block 12Fa and the second cylinder block 12Ra. These stud bolts 50 fasten the components of the front and rear cylinder sections 12F, 12R together to the crankcase 11. In the example shown in Figure 3, stud bolts 50 are provided at the four corners of the periphery of each cylinder bore 15, and the four stud bolts 50 fasten the periphery of each cylinder bore 15. A common stud bolt 50 is provided where the peripheries of adjacent cylinder bores 15 overlap. The common stud bolt 50 is arranged on the center line AX between the left and right sides of the engine 1. By arranging the stud bolt 50 on the center line AX, it becomes easier to fasten the components of the front and rear cylinder sections 12F, 12R so that the surface pressure between them is more uniform. It should be noted that the center line AX shown in Figures 3 and 4 is not limited to the lateral center of the engine 1 in the strict sense (corresponding to the axial center of the crankshaft 10), but may be the lateral center of the engine 1 or the vicinity of the lateral center, for example, the lateral center or the vicinity of the lateral center of the first cylinder section 12F, or the lateral center or the vicinity of the lateral center of the second cylinder section 12R.

[0032] In the example shown in Figure 4, stud bolts 50 are provided at the four corners around each cylinder bore 15, as well as in front of and behind the left-right center of each cylinder bore 15. The stud bolts 50 provided in front of and behind the left-right center of each cylinder bore 15 are positioned on the center line AX between the left and right sides of the engine 1. This makes it easier to fasten the components of the front and rear cylinder sections 12F, 12R so that the surface pressure between them is more uniform.

[0033] The first pipe 45 is positioned offset to one side (left) from the center line AX between the left and right sides of the engine 1. This prevents the first pipe 45 from overlapping with the stud bolts 50 positioned on the center line AX, and allows the first pipe 45 to connect the coolant passages 13Fa, 13Ra of the front and rear cylinder blocks 12Fa, 12Ra to each other. 3 and 4, reference numeral 25 denotes a cam chain chamber. The cam chain chamber 25 is formed on either the left or right side of each cylinder portion 12F, 12R, and accommodates a cam chain that transmits the rotation of the crankshaft 10 to the valve train 20.

[0034] [Other embodiments] The above-described embodiment merely shows one aspect of the present invention, and any modifications and applications are possible without departing from the spirit of the present invention.

[0035] In the above embodiment, a water-cooled V-type engine 1 mounted on a saddle-ride type vehicle has been described, and a four-cylinder engine or a two-cylinder engine has been described, but the number of cylinders of the engine 1 of the present invention may be changed as appropriate. Furthermore, the engine 1 of the present invention is not limited to an engine mounted on a motorcycle, but may be, for example, an engine mounted on a three-wheeled saddle-ride type vehicle having two front or two rear wheels, or a saddle-ride type vehicle having four or more wheels. Furthermore, the present invention may also be applied to an engine not mounted on a vehicle.

[0036] In the above-described embodiment, the present invention is described as being applied to a horizontally mounted engine in which the axial direction of the crankshaft 10 is in the left-right direction of the motorcycle and the first cylinder section 12F and the second cylinder section 12R are arranged in a front-to-rear direction, but is not limited to this. For example, the present invention may be applied to a longitudinally mounted engine in which the axial direction of the crankshaft 10 is in the longitudinal direction of the motorcycle and the first cylinder portion 12F and the second cylinder portion 12R are aligned on the left and right.

[0037] In the above embodiment, the cooling water can be referred to as a cooling refrigerant, and the cooling water can be widely used in known engines.

[0038] [Configuration supported by the above embodiment] The above embodiment supports the following configurations.

[0039] (Configuration 1) An engine having a first cylinder section having a first cylinder head and a first cylinder block, a second cylinder section having a second cylinder head and a second cylinder block, and a water pump that pressurizes cooling water, the engine having a cooling water circulation passage through which the cooling water pumped out from the water pump circulates in the following order: first cylinder block, second cylinder block, second cylinder head, and first cylinder head. This allows the flow of cooling water to the front and rear cylinder sections to be one, which reduces temperature variations between the front and rear cylinder sections and also reduces the amount of cooling water required, allowing for efficient warm-up.

[0040] (Configuration 2) The engine described in Technology 1, wherein the cooling water circulation passage includes a first pipe connecting the first cylinder block and the second cylinder block, and a second pipe connecting the first cylinder head and the second cylinder head. According to this, the cooling water passage connecting the front and rear cylinder sections is constructed by pipes, so that the cooling water circulation passage can have a simple structure, and the engine assembly workability and maintenance are improved.

[0041] (Configuration 3) The engine described in Technology 2, further comprising a crankshaft and a crankcase supporting the crankshaft, wherein the first pipe is positioned offset to one side with respect to a center line of the first cylinder block in the crankshaft direction. This allows the first pipe to be positioned to avoid the stud bolts on the center line of each cylinder block in the crankshaft direction, and the stud bolts can be positioned so that the surface pressure between the components of the cylinder section is uniform.

[0042] (Configuration 4) The engine according to Configuration 2 or 3, further comprising a crankshaft and a crankcase supporting the crankshaft, wherein the first pipe and the second pipe are arranged offset vertically as viewed from the crankshaft direction. According to this, by disposing the first pipe and the second pipe so as to be vertically offset, the workability of assembling the engine is improved.

[0043] (Configuration 5) The engine described in any one of Techniques 1 to 4, wherein a thermostat case that houses a thermostat is disposed around the exhaust port of the first cylinder head, and the cooling water circulation passage causes the cooling water to pass through the thermostat downstream of the first cylinder head. This allows the thermostat to control the flow of cooling water at the point where the temperature of the cooling water is highest, which is suitable for accurate temperature management of the engine.

[0044] (Configuration 6) An engine according to any one of techniques 1 to 5, comprising a crankshaft and a crankcase supporting the crankshaft, the crankshaft being disposed in the left-right direction relative to the vehicle body, and the water pump being driven by rotation of the crankshaft and disposed on the right front side of the crankcase. This allows the water pump to be positioned close to the crankshaft and first cylinder block, shortening the power transmission path between the water pump and the crankshaft and the cooling water passage between the water pump and the first cylinder block, allowing the cooling water to circulate efficiently and allowing for efficient warm-up, etc. [Explanation of symbols]

[0045] 1 engine 10 crankshaft 11 Crankcase 12F First Cylinder Section 12Fa No. 1 cylinder block 12Fb No. 1 cylinder head 12R 2nd cylinder section 12Ra No. 2 cylinder block 12Rb No. 2 cylinder head 13Fa Cooling water passage 13Fb Cooling water passage 13Ra Cooling water passage 13Rb Cooling water passage 44 Water pump 45 First Pipe 46 Second Pipe 47 Thermo Case 47a Thermostat

Claims

1. A water-cooled V-type engine including a first cylinder section (12F) having a first cylinder head (12Fb) and a first cylinder block (12Fa), a second cylinder section (12R) having a second cylinder head (12Rb) and a second cylinder block (12Ra), and a water pump (44) that pumps cooling water, a cooling water circulation passage through which cooling water delivered from a water pump (44) circulates in the order of the first cylinder block (12Fa), the second cylinder block (12Rb), the second cylinder head (12Ra), and the first cylinder head (12Fa); engine.

2. The cooling water circulation passage includes a first pipe (45) connecting the first cylinder block (12Fa) and the second cylinder block (12Ra), and a second pipe (46) connecting the first cylinder head (12Fb) and the second cylinder head (12Ra).

10. The engine of claim 1.

3. The engine comprises a crankshaft (10) and a crankcase (11) supporting the crankshaft (10), the first pipe (45) is disposed offset to one side with respect to a center line (AX) in the crankshaft direction of the first cylinder block (12Fa); 3. The engine of claim 2.

4. The engine comprises a crankshaft (10) and a crankcase (11) supporting the crankshaft (10), The first pipe (45) and the second pipe (46) are arranged to be vertically shifted from each other when viewed from the crankshaft direction.

3. The engine of claim 2.

5. A thermo case (47) accommodating a thermostat (47a) is disposed around the exhaust port of the first cylinder head (12Fb), The cooling water circulation passage causes the cooling water to pass through the thermostat (47a) downstream of the first cylinder head (12Fb).

10. The engine of claim 1.

6. The engine comprises a crankshaft (10) and a crankcase (11) supporting the crankshaft (10), The crankshaft (10) is disposed in the left-right direction with respect to the vehicle body, The water pump (44) is driven by the rotation of the crankshaft (10) and is disposed on the right front side of the crankcase (11).

10. The engine of claim 1.

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