WO2015146832A1

WO2015146832A1 - Cooling passage structure for engine

Info

Publication number: WO2015146832A1
Application number: PCT/JP2015/058493
Authority: WO
Inventors: 文則水谷; 玲奈黒須
Original assignee: 本田技研工業株式会社
Priority date: 2014-03-28
Filing date: 2015-03-20
Publication date: 2015-10-01
Also published as: CN105849378A; CN105849378B; PH12016501708B1; JP6139779B2; JPWO2015146832A1; MY186348A; PH12016501708A1

Abstract

A cooling passage structure for an engine is configured in such a manner that the discharge opening of a water pump is disposed facing the position of a crank case, which is located near the rear of a cylinder block. In a side view of the engine, an introduction passage is formed within the walls of both the crank case and the cylinder block in such a manner that the introduction passage extends substantially parallel to the cylinder central axis of the cylinder block from the discharge opening and is connected to a peripheral wall cooling passage.

Description

Engine cooling passage structure

The present invention relates to a cooling passage structure of a water-cooled engine.
Priority is claimed on Japanese Patent Application No. 2014-68393, filed March 28, 2014, the content of which is incorporated herein by reference.

As an engine mounted in vehicles, such as a two-wheeled motor vehicle, there exists a water-cooled engine which cools the inside of a cylinder block with a cooling water. In this engine, cooling water is supplied from a water pump attached to the crankcase, and the cooling water circulates a water jacket (peripheral wall cooling passage) in the cylinder block to cool the engine block including the cylinder block. .

In this type of engine, it is necessary to supply the cooling water discharged from the water pump to the water jacket through the introduction passage, but configuring the introduction passage with an external pipe complicates the structure around the cylinder block and cylinder head .
For this reason, it is known to mount a water pump on the top of the crankcase near the front end and introduce the cooling water discharged from the water pump into the water jacket through the introduction passage in the wall of the crankcase and cylinder block ( For example, refer to Patent Document 1).

Japan JP 2011-163249

When the cooling water introduction passage is formed in the wall of the crankcase and cylinder block as in the engine described in Patent Document 1, the arrangement of the introduction passage is designed using dead space in the engine block As a result, the degree of freedom in handling becomes lower than in the case of external piping, and the number of bends increases, the passage structure becomes complicated, and the flow path resistance also tends to increase.
In this case, if the cylinder block is an engine that leans forward with respect to the crankcase, the cooling water introduced from the front lower end of the cylinder block is the entire water jacket of the cylinder block, particularly near the rear lower end of the cylinder block It becomes difficult to be supplied to As a countermeasure, in order to increase the discharge flow rate, it is necessary to adopt a large water pump.
However, in this case, the increase in the size of the water pump results in the increase in the size and weight of the entire engine.

According to an aspect of the present invention, an engine capable of efficiently supplying cooling water discharged from a water pump to the entire area in a cylinder block even when the cylinder block is inclined forwardly upward with respect to a crankcase It is an object of the present invention to provide a cooling passage structure of

(1) A cooling passage structure of an engine according to one aspect of the present invention includes a crankcase rotatably supporting a crankshaft, and a forwardly inclined upper front in a side view and coupled to the crankcase to slide a piston A cylinder block having a peripheral wall cooling passage for freely circulating the cooling water, a water pump attached to the crankcase and discharging the cooling water, and a discharge port of the water pump and the peripheral wall cooling passage are connected. An inlet passage for cooling water, wherein the outlet of the water pump is disposed opposite to a position near the rear of the cylinder block in the crankcase, and the inlet passage is viewed in a side view of the engine Front from the discharge port so as to extend substantially parallel to the cylinder center axis of the cylinder block and to be connected to the peripheral wall cooling passage; It is formed in the wall of the crank case and the cylinder block.

According to the above aspect (1), the coolant discharged from the water pump is introduced into the crankcase at a position near the rear of the cylinder block. The coolant introduced into the crankcase is introduced into the peripheral wall cooling passage in the cylinder block through the crankcase extending substantially parallel to the cylinder center axis and the introduction passage in the wall of the cylinder block. At this time, the introduction passage is smoothly introduced into the peripheral wall cooling passage without being bent in a complicated manner at a position near the rear of the cylinder block. Then, since the cooling water is introduced into the peripheral wall cooling passage from the lower end side of the forwardly inclined cylinder block near the rear part of the cylinder block, the cooling water flows efficiently throughout the entire region in the peripheral wall cooling passage.

(2) In the aspect of the above (1), the peripheral wall cooling passage is a radial direction from the base portion at a position where it is connected to the substantially annular base portion centered on the cylinder center axis and the introduction passage. And an expanded portion having an enlarged volume outside.

According to the above aspect (2), the peripheral wall cooling passage is provided with an expanded portion whose volume is expanded radially outward from the base portion, and the introduction passage is connected to the expanded portion. For this reason, the introduction passage can be maintained substantially in a straight line without bending the introduction passage, while being disposed on the radially outer side of the cylinder block with respect to the base portion of the peripheral wall cooling passage. For this reason, it is possible to further reduce the flow resistance in the introduction passage.

(3) In the aspect of (1) or (2), the cylinder block is fixed to the crankcase by a fastening member at a position near the front of the cylinder block in a side view of the engine. In a side view of the engine, it is fixed to the crankcase by a fastening member at a position near the rear of the cylinder block, and an outlet of the water pump is an axial extension of the fastening member near the front of the cylinder block It may be arrange | positioned in the area | region pinched | interposed into the exit position and the axial extension position of the said fastening member near the rear part of the said cylinder block.

According to the above aspect (3), since the discharge port of the water pump is disposed between the axially extending positions of the front and rear fastening members, the main part of the introduction passage connected to the discharge port and the peripheral wall cooling path The distance to the unit can be made closer. For this reason, the flow resistance of the coolant can be further reduced by shortening the distance from the discharge port of the water pump to the main part of the peripheral wall cooling passage.

(4) In the above aspect (3), the pump body portion of the water pump includes an axial extension position of the fastening member near the front of the cylinder block and a fastening member near the rear of the cylinder block. It may be disposed in an area between the axially extending position.

According to the above aspect (4), the distance from the pump main body of the water pump to the main part of the peripheral wall cooling passage becomes short, and the flow resistance of the coolant can be further reduced.

(5) In the aspect according to any one of the above (1) to (4), the water pump is integrally formed in a crank cover which partially covers a side surface of the crankcase and which accommodates a pump operation portion. The portion of the crank cover on which the discharge port of the casing portion is formed may be formed so as to protrude toward the recess of the side surface of the crankcase.

According to the above aspect (5), since the portion of the crank cover on which the discharge port is to be formed is disposed in the recess of the side surface of the crankcase, the discharge port of the water pump It can be brought closer to the position directly below.

(6) In the above aspect (5), the axial end face of the casing portion of the water pump on the opposite side to the crankcase is closed by the pump cover, and the connection passage connected to the discharge port in the casing portion The crankcase side may be formed to be deeper toward the discharge port side.

According to the above aspect (6), since the connection passage connected to the discharge port is deeper toward the discharge port side on the crankcase side, the cross-sectional area of the connection path can be secured on the crank cover side. For this reason, it is not necessary to provide the recessed part for ensuring the cross-sectional area of a connection path in the pump cover side, and the end surface of a pump cover can be made flat. Therefore, the expansion of the pump cover to the outside can be reduced, and the overall size of the engine can be reduced.

(7) In the aspect of any one of (1) to (6), the cylinder block includes an oil supply passage extending from the front area to the rear area of the cylinder block at the joint surface with the crankcase. The introduction passage for cooling water may be formed to pass through the outside of the oil supply passage in the cylinder block.

According to the above aspect (7), since the oil supply passage is disposed along the outer edge of the cylinder bore inside the cooling water introduction passage, the passage length of the oil supply passage can be shortened. Therefore, the flow resistance of oil in the oil supply passage can be reduced.

(8) In the aspect of any one of the above (1) to (7), the cylinder block is a cast part, and the downstream passage hole constituting a part of the introduction passage on the cylinder block side; The peripheral wall cooling passage of the cylinder block may be formed by casting.

According to the above aspect (8), since the peripheral wall cooling passage and the downstream passage hole of the cylinder block are formed by casting, machining such as cutting after casting of the cylinder block is reduced, and manufacturing cost is reduced. be able to.

According to the aspect of the present invention, the cooling water discharged from the water pump rises linearly from the position near the rear of the cylinder block substantially parallel to the cylinder center axis, and the rear in the peripheral wall cooling passage in the cylinder block It is introduced from the lower end side. For this reason, the cooling water can be efficiently supplied to the entire area in the cylinder block, even though the cylinder block has an engine structure in which the front side is inclined forward with respect to the crankcase.

FIG. 1 is a left side view of a motorcycle adopting a power unit according to an embodiment of the present invention. It is a right side view of the power unit of one embodiment of the present invention. It is a left side view of a power unit of one embodiment of the present invention. FIG. 4 is a cross-sectional view substantially corresponding to the IV-IV cross section of FIG. 2 of a power unit according to an embodiment of the present invention. FIG. 5 is a cross-sectional view substantially corresponding to the VV cross-section of FIG. 2 of the power unit of one embodiment of the present invention. It is a bottom view corresponding to VI arrow of Drawing 2 of a cylinder block of one embodiment of the present invention. FIG. 7 is a partial cross-sectional perspective view of a power unit according to an embodiment of the present invention taken along the line VII-VII in FIG. 6; It is an enlarged view of the VIII section of FIG. 4 of the power unit of one Embodiment of this invention. It is the right side view which removed the pump cover of the power unit of one embodiment of the present invention. It is a top view corresponding to X arrow of FIG. 9 of the power unit of one Embodiment of this invention. FIG. 11 is a partial cross-sectional perspective view of a power unit according to an embodiment of the present invention taken along the line XI-XI in FIG. FIG. 10 is a cross-sectional view corresponding to the XII-XII cross section of FIG. 9 of a power unit according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. An arrow FR indicating the front of the vehicle, an arrow LH indicating the left of the vehicle, and an arrow UP indicating the upper of the vehicle are shown at appropriate positions in the drawings used for the following description.
FIG. 1 is a view showing a left side surface of a motorcycle 1 equipped with a power unit PU employing an engine E according to the present embodiment.
In FIG. 1, the front wheel Wf is supported by a vehicle body frame (not shown) via a front fork 2. The rear wheel Wr is supported by the vehicle body frame via the swing arm 3. The steering wheel H is disposed above the front fork 2. The seat S is a seat on which an occupant sits. The fuel tank T is disposed in front of the seat S. The power unit PU is mounted below the fuel tank T at the center of the vehicle body frame.
The power unit PU shifts the drive rotation of the engine E by the transmission M and transmits the output thereof to the rear wheel Wr via the transmission mechanism. In the following description of the power unit PU, the directions such as front, rear, left, and right are the same as the directions when mounted on a vehicle unless otherwise specified.

2 and 3 are diagrams showing the right side surface and the left side surface of the power unit PU. 4 and 5 are cross-sectional views substantially corresponding to the IV-IV cross section and the VV cross section of FIG. 2 in the power unit PU.
The engine E of the power unit PU includes a crankcase 11 that rotatably supports the crankshaft 10, and a cylinder portion 12 that protrudes obliquely upward from a front upper portion of the crankcase 11. The crankcase 11 doubles as a transmission case of the transmission M, and the crankshaft 10 is disposed on the front side, and the main shaft 13 and the countershaft 14 of the transmission M are cranked on the rear side of the crankshaft 10 It is arranged parallel to the axis 10. The main shaft 13 and the counter shaft 14 are rotatably supported by the crankcase 11. As shown in FIG. 4, the countershaft 14 penetrates the left side wall of the crankcase 11 to the outside, and a sprocket 15 for power extraction is attached to the penetrating end. A chain 9 is wound around the sprocket 15, and power is transmitted to the rear wheel Wr (see FIG. 1) through the chain 9.

The cylinder portion 12 is attached to an upper portion of the cylinder block 17 having a cylinder bore 17a for accommodating the piston 16 in a retractable manner, and forms a combustion chamber 7 (see FIG. 4) with the top surface of the piston 16 And a head cover 19 mounted on the top of the cylinder head 18. As shown in FIGS. 2 and 5, the cylinder head 18 is overlapped on the upper portion of the cylinder block 17, and a plurality of (four in this embodiment) stud bolts 20 (fastening members) are mounted on the upper surface of the crankcase 11 together with the cylinder block 17. Fixed together by).

The piston 16 is operatively connected to the crankshaft 10 via a connecting rod 23, and transmits to the crankshaft 10 an advancing / retracting operation of the piston 16 accompanying the explosion in the combustion chamber 7 as a rotational force. In FIG. 4, the spark plug 8 is provided facing the combustion chamber 7.

An intake port (not shown) is formed in the cylinder head 18, and an intake valve (not shown) is attached to open and close the intake port. An exhaust port (not shown) is formed in the cylinder head 18, and an exhaust valve (not shown) for opening and closing the exhaust port is attached. As shown in FIGS. 2 and 3, an inlet pipe 6 that constitutes an intake system of the engine E is connected to the intake port. An exhaust pipe (not shown) that constitutes an exhaust system of the engine E is connected to the exhaust port. Further, as shown in FIG. 5, a valve operating mechanism 21 is provided between the cylinder head 18 and the head cover 19 for opening and closing the intake and exhaust valves. The cam shaft 22 in FIG. 5 operates the valve operating cam of the valve operating mechanism 21. The camshaft 22 is connected to the crankshaft 10 via the timing chain 5 so as to be interlockable.
The engine E of the present embodiment is a water-cooled single-cylinder engine. The cylinder block 17 is provided with a single cylinder bore 17a, and a water jacket 50, which is a peripheral wall cooling path, is formed around the cylinder bore 17a. Cooling water cooled by a radiator (not shown) is pumped from a water pump 51 described later in detail to the water jacket 50.

As shown in FIGS. 4 and 5, the crankcase 11 is constituted by a pair of case halves 11L and 11R which are divided left and right with division surfaces 11La and 11Ra orthogonal to the crankshaft 10 as boundaries. The pair of case halves 11L and 11R are divided into right and left in a plane passing through the cylinder center axis C1 of the cylinder block 17. The divided case halves 11L and 11R are fastened and fixed to each other by a plurality of bolts (not shown). A crank cover 30 which forms a sealed space with the case half 11R is attached to the right side of the right case half 11R.

As shown in FIG. 4, the right end of the crankshaft 10 penetrates the side wall of the right case half 11R. A primary drive gear 24 for transmitting power to the main shaft 13 of the transmission M is attached to the penetrating end. The left end of the crankshaft 10 passes through the side wall of the left case half 11L. The rotor 25a of the generator 25 is attached to the penetrating end. The end and the circumferential area of the rotor 25a are covered by a cover 25c of the generator 25 that holds the stator 25b.

The right end of the main shaft 13 of the transmission M penetrates the side wall of the right case half 11R. At the end of the main shaft 13 penetrating the right case half 11R, a primary driven gear 26 engaged with the primary drive gear 24 on the crankshaft 10 side and a clutch 27 for connecting and disconnecting power by external operation are supported It is done. The primary driven gear 26 is rotatably supported by the main shaft 13. The clutch 27 is interposed in a power transmission path between the primary driven gear 26 and the main shaft 13. Therefore, the clutch 27 can appropriately switch transmission and disconnection of power between the primary driven gear 26 and the main shaft 13 by an operation from the outside.

The main shaft 13 of the transmission M is provided with a main gear group m1 composed of a plurality of transmission gears. The counter shaft 14 of the transmission M is provided with a counter gear group m2 composed of a plurality of transmission gears. In the transmission M, the transmission gears of the main gear group m1 and the counter gear group m2 are selected by the operation of a change mechanism (not shown), whereby an arbitrary transmission gear (gear position) including neutral is set. Therefore, when the rotational power of crankshaft 10 is transmitted to main shaft 13 through clutch 27 in the state where the transmission gear is set, transmission M shifts the rotational power to the set ratio and performs counter operation. Output from the axis 14 to the outside.
The kick shaft 28 in FIG. 4 rotates the crankshaft 10 at the time of kick start.

As shown in FIGS. 2 and 3, a balancer shaft 29 extending parallel to the crankshaft 10 is disposed at an upper position between the crankshaft 10 and the main shaft 13 in the crankcase 11. The balancer shaft 29 is rotatably supported by the crankcase 11. The balancer shaft 29 rotates in synchronization with the crankshaft 10 via a gear (not shown) to cancel the rotational fluctuation of the crankshaft 10 and maintain the rotational balance.

Further, as shown in FIG. 5, an oil pan 31 is provided at the bottom of the crankcase 11 for storing lubricating oil. An oil pump 32 is provided at an upper position of the oil pan 31 of the right case half 11R, for drawing up the oil in the oil pan 31 and pumping the oil to a portion requiring lubrication in the power unit PU. The oil pump 32 of the present embodiment is operated by receiving rotational power from the crankshaft 10.

The oil supply passage 33 in the power unit PU connected to the oil pump 32 passes oil from the discharge part of the oil pump 32 through the inside of the crankshaft 10 to supply oil to parts requiring lubrication around the crankshaft 10 such as crank pins and journals. It is divided into a crank system oil passage 33C, and a valve system oil passage 33B for supplying oil from the upper portion of the crankcase 11 through the inside of the wall of the cylinder portion 12 to a portion requiring lubrication of the valve mechanism 21. A branch oil passage 34 for supplying oil around the main shaft 13 of the transmission M, the counter shaft 14 and the like is connected midway of the valve system oil passage 33B.

6 is a bottom view of the cylinder block 17 corresponding to the arrow VI of FIG. FIG. 7 is a perspective view of the crankcase 11 and the cylinder block 17 in which the VII-VII cross section in FIG.
As shown in FIG. 5, a part of the valve system oil passage 33 B of the oil supply passage 33 is between the end face 11 Ru, 11 Lu (joint surface) of the upper part of the crankcase 11 and the lower surface 17 d (joint surface) of the cylinder block 17. Is formed. As shown in FIG. 6, the oil passage between the joint surfaces of the crankcase 11 and the cylinder block 17 is provided with an oil inflow portion 35a connected to the oil pump 32 in the vicinity of the front right corner of the cylinder block 17. An oil outlet 36 a connected to the valve operating mechanism 21 is provided at the rear left corner of the cylinder block 17.

The oil passage between the joint surfaces of the crankcase 11 and the cylinder block 17 described above is a first oil passage 35 formed between the end face 11Ru of the right case half 11R and the lower surface 17d of the cylinder block 17; A second oil passage 36 formed between the end face 11Lu of the case half 11L and the lower surface 17d of the cylinder block 17 is provided.
The first oil passage 35 is surrounded by a flat end face 11Ru of the right case half 11R and a groove 35c formed on the lower surface 17d of the cylinder block 17 substantially along the outer peripheral edge of the cylinder bore 17a. It is formed. At one end of the first oil passage 35 in the extending direction, an inflow portion 35 a connected to the oil pump 32 is provided. The second oil passage 36 is surrounded by a flat end face 11Lu of the left case half 11L and a groove 36c formed in the lower surface 17d of the cylinder block 17 substantially along the outer peripheral edge of the cylinder bore 17a. It is formed. At one end in the extension direction of the second oil passage 36, an outflow portion 36a connected to the valve operating mechanism 21 side is provided.
In FIG. 5, the portions to be cross-sectioned are adjusted so that the first oil passage 35 and the second oil passage 36 appear on the drawing.

The first oil passage 35 extends in an arc from the inflow portion 35a on the front right side of the cylinder block 17 through the rear right side of the cylinder block 17 to the vicinity of the center of the rear portion and ends in the vicinity of the rear center . As shown in FIGS. 5 and 7, one end of a first bypass hole 37 formed in the right case half 11R is electrically connected to the other end of the first oil passage 35.
The second oil passage 36 extends in an arc from the outflow portion 36 a on the rear left side of the cylinder block 17 to the vicinity of the rear center of the cylinder block 17 and ends in the rear vicinity of the rear center. As shown in FIGS. 5 and 7, one end of a second bypass hole 38 formed in the left case half 11L is electrically connected to the other end of the second oil passage 36.

The first bypass hole 37 is constituted by a substantially L-shaped hole whose one end opens at the upper end surface 11Ru of the right case half 11R. The other end 37a of the first bypass hole 37 opens at a position apart from the upper end surface 11Ru of the divided surface 11Ra of the right half case 11R.
The second bypass hole 38 is constituted by a substantially L-shaped hole whose one end opens at the upper end surface 11Lu of the left case half 11L. The other end 38a of the second bypass hole 38 opens at a position apart from the upper end surface 11Lu of the divided surface 11La of the left case half 11L. The other end 37a of the first bypass hole 37 and the other end 38a of the second bypass hole 38 are connected to each other because the left and right case halves 11L and 11R are joined together. It is done.
Therefore, the first oil passage 35 and the second oil passage 36 are mutually connected via the first bypass hole 37 and the second bypass hole 38. Thus, the oil flowing from the oil pump 32 into the inflow portion 35a sequentially passes through the first oil passage 35, the first bypass hole 37, the second bypass hole 38, the second oil passage 36, and the outflow portion 36a. The valve mechanism 21 of the unit 12 is supplied.

Further, in the second bypass hole 38, the vertical hole extending downward from the upper end surface 11Lu of the case half 11L is further extended by a predetermined length beyond the horizontal hole connected to the first bypass hole 37 side. ing.
A branched oil passage 34 for supplying oil around the main shaft 13 of the transmission M, the counter shaft 14 and the like is connected to the side surface spaced apart from the bottom of the extension 40.

In the cylinder block 17, as shown in FIG. 6, insertion holes 39 into which the above-described stud bolt 20 is inserted are formed at four corners of the peripheral portion surrounding the cylinder bore 17 a. The inflow portion 35 a is disposed in the vicinity of the insertion hole 39 at the front right of the cylinder block 17. The outflow portion 36 a is disposed in the vicinity of the insertion hole 39 at the left rear of the cylinder block 17. The first oil passage 35 and the second oil passage 36 are formed substantially half a circumference around the cylinder bore 17a across the position of the divided surfaces 11La and 11Ra of the crankcase 11.

Here, the flow of oil in the power unit PU will be described.
When the crankshaft 10 is rotated by the drive of the engine E, the oil pump 32 is operated in response to the rotation of the crankshaft 10. As shown in FIG. 5, the oil pump 32 sucks up the oil stored in the oil pan 31 and discharges the oil to the oil supply passage 33 side. The oil discharged from the oil pump 32 branches into a crank system oil passage 33C and a valve system oil passage 33B at the upper part of the case half 11R on the right side of the crankcase 11. The oil which has flowed into the crank system oil passage 33C passes from the right end of the crankshaft 10 through a passage in the crankshaft 10 and is supplied to a portion requiring lubrication around the crankshaft 10 such as a crank pin and a journal portion.

On the other hand, the oil flowing into the valve system oil passage 33B passes through a passage extending upward from the front right side of the right case half 11R, and as shown in FIGS. 5 and 6, the upper side of the right case half 11R. The fluid flows into the first oil passage 35 formed between the end face 11Ru of the first block and the lower surface 17d of the cylinder block 17 through the inflow portion 35a.

The oil that has flowed into the first oil passage 35 flows around the cylinder bore 17a along the first oil passage 35 in an arc toward the rear center side, and downwards in the portion immediately before the dividing surface 11Ra of the right half case 11R. Flow into the first bypass hole 37 of the case half 11R.

The oil that has flowed into the first bypass hole 37 changes its direction substantially in the L shape at the lower end in the direction of the split surface 11La, and the split surface 11Ra of the right case half 11R and the split surface 11La of the left case half 11L. Flow into the second bypass hole 38 of the left case half 11L with the joint portion between the two. A portion of the oil that has flowed into the second bypass hole 38 turns substantially L-shaped upward, and between the upper end surface 11Lu of the left case half 11L and the lower surface 17d of the cylinder block 17 It flows into the formed second oil passage 36. Further, the remaining oil which has flowed into the second bypass hole 38 turns downward and flows into the extension 40, and flows from the side surface of the extension 40 into the branch oil passage 34 on the transmission M side.

The oil flowing into the second oil passage 36 from the second bypass hole 38 flows from the rear center side of the cylinder block 17 around the cylinder bore 17a toward the outflow portion 36a near the rear left corner, and from the outflow portion 36a to the cylinder block It is supplied to the necessary lubrication part of the valve mechanism 21 through the passage in the inside of the reference numeral 17.

FIG. 8 is a cross-sectional view of the water pump 51 showing an enlarged view of a portion VIII of FIG.
The water pump 51 according to the present embodiment is a spiral pump in which the impeller 52, which is a pump operation unit, rotates in the casing 53 and discharges the cooling water sucked from the axial direction in the centrifugal direction. The casing portion 53 is formed across the crank cover 30 and the pump cover 54 attached to the right side surface of the crank cover 30. The impeller 52 is integrally attached to one end side of a pump shaft 55 rotatably supported by the crank cover 30. A pump gear 57 engaged with the primary drive gear 24 of the crankshaft 10 is integrally provided at the other end of the pump shaft 55. The water pump 51 of the present embodiment receives power from the crankshaft 10 and operates as a pump.
The mechanical seal 56 in FIG. 8 seals between the pump shaft 55 and the crank cover 30 in a fluid-tight manner.

FIG. 9 shows the right side of the engine E with the pump cover 54 of the water pump 51 removed. FIG. 10 is a view of the engine E from above the cylinder block 17 with the cylinder head 18 removed. FIG. 11 is a partial cross-sectional perspective view of the cylinder block 17 and the crankcase 11 in which the XI-XI portion of FIG. 10 is a cross section.
As shown in FIGS. 9 to 11, the water pump 51 is disposed at the front upper edge position of the crank cover 30 covering the right side of the crankcase 11 (the right case half 11R). Specifically, as shown in FIG. 9 and FIG. 10, the main part (including the pump chamber 60 described later) of the water pump 51 fastens and fixes the cylinder block 17 to the crankcase 11 in a side view of the engine E. In the region A1 sandwiched between the axial extension position of the front stud bolt 20 and the axial extension position of the rear stud bolt 20.

The suction port 58 of the water pump 51 is formed in the pipe connection nozzle 48 of the pump cover 54, as shown in FIG. As shown in FIGS. 9 and 10, the discharge port 59 of the water pump 51 is formed to open at the joint surface of the crank cover 30 with the crankcase 11 (case half 11R on the right side). The discharge port 59 is provided at an end portion of a connection passage 61 which spirally extends outward in the radial direction from a pump chamber 60 (pump main body portion) in which the impeller 52 is accommodated. As shown in FIG. 9, the pump chamber 60 is disposed at a position overlapping the central axis C1 of the cylinder block 17 in a side view of the engine E. The discharge port 59 is disposed to face the cylinder block 17 at a position near the rear of the cylinder block 17 in the crankcase 11 (the case half 11R on the right side). The discharge port 59 is precisely disposed in the vicinity of the extension position of the rear side stud bolt 20 and on the front side of the extension position of the stud bolt 20. Therefore, the discharge port 59 is disposed in a region A1 sandwiched by the axially extending position of the stud bolt 20 near the front of the cylinder block 17 and the axial extending position of the stud bolt 20 near the rear There is.

As shown in FIG. 11, an introduction port 62a of an introduction passage 62 connected to the water jacket 50 is provided at a position opposite to the discharge port 59 of the water pump 51 of the crankcase 11 (right half case 11R). . The introduction passage 62 is formed in the cylinder block 17 substantially in parallel with the cylinder center axis C1 and an upstream passage hole 63 formed by bending substantially in an L shape in the right case half 11R. And a side passage hole 64.

The upstream passage hole 63 extends upward from the inlet 62a opened on the right side surface of the right case half 11R in parallel with the crankshaft 10 toward the left side of the right case half 11R and then bends upward. The upper end portion of the upstream side passage hole 63 opens at the upper end surface 11Ru of the right case half 11R.

Further, the downstream side passage hole 64 is formed extending substantially in the vertical direction at the rear right corner of the cylinder block 17, and the lower end is an opening of the upstream side passage hole 63 of the end surface 11Ru of the right case half 11R. Butted and connected. The downstream passage hole 64 extends upward while being slightly curved from the lower end toward the cylinder center axis C1. Further, as shown in FIG. 6, the downstream passage hole 64 at the rear right corner of the cylinder block 17 is radially outside the oil supply passage 33 (groove 35c) between the joint surfaces of the crankcase 11 and the cylinder block 17. Is located in Therefore, the cooling water introduction passage 62 is formed to pass through the outside of the oil supply passage 33 between the joint surfaces of the crankcase 11 and the cylinder block 17.

On the other hand, as shown in FIG. 10, the water jacket 50 of the cylinder block 17 is connected to the substantially annular base portion 50a centered on the cylinder center axis C1 and the introduction passage 62 (downstream passage hole 64). And an expanded portion 50b whose volume is expanded substantially in a semicircular shape radially outward from the base portion 50a. The extended portion 50b of the water jacket 50 can conduct with the water jacket 50 without radially bending the upper portion of the downstream passage hole 64 formed substantially parallel to the cylinder center axis C1 in the cylinder block 17 It is formed.

Moreover, the cylinder block 17 of this embodiment is formed by casting. The water jacket 50 of the cylinder block 17 and the downstream passage hole 64 of the introduction passage 62 connected to the expanded portion 50 b of the water jacket 50 are formed by casting at the time of casting.

As shown in FIGS. 4 and 8, a portion of the casing portion 53 of the water pump 51 is integrally formed at the front upper edge position of the crank cover 30, and the front upper edge position of the crank cover 30 is It is joined to the right side of crankcase 11 (case half 11R on the right). A recessed portion 65 recessed in a step-like manner in the direction of the cylinder center axis C1 is formed in a portion of the right side surface of the crankcase 11 to which the casing portion 53 is joined. The portion of the casing 53 of the water pump 51 where the discharge port 59 is formed is a discharge portion 53 a that protrudes in the right side direction of the crankcase 11. The water pump 51 is joined to the right side surface of the crankcase 11 in a state in which the discharge part 53a is fitted in the recess 65 of the crankcase 11 (case half 11R on the right side). Therefore, a portion of the casing portion 53 of the water pump 51 is disposed so as to partially enter the crankcase 11 side.

FIG. 12 is a cross-sectional view corresponding to the XII-XII cross section of FIG.
As shown in FIGS. 9 and 12, the connection passage 61 connecting the pump chamber 60 and the discharge port 59 of the water pump 51 has a depth when viewed from the pump cover 54 side is the pump chamber 60 to the discharge port 59 side. Gradually becoming deeper toward the crankcase 11 side. A wall 66 in FIG. 12 is a side wall on which the depth of the connection path 61 is gradually deepened.

Here, the flow of the cooling water in the engine E portion of the power unit PU will be described.
When the primary drive gear 24 drives the pump gear 57 with the rotation of the crankshaft 10 and the pump gear 57 rotates the impeller 52 of the water pump 51 via the pump shaft 55 integrally fixed to the pump gear 57. The cooling water sucked from the suction port 58 is pumped by the impeller 52. The cooling water pumped by the impeller 52 is discharged to the discharge port 59 through the spiral connection path 61.
The cooling water discharged from the discharge port 59 flows into the upstream side passage hole 63 of the introduction passage 62 from the introduction port 62 a of the crankcase 11 positioned at the lower right side of the cylinder block 17. The cooling water having flowed into the upstream side passage hole 63 turns upward substantially in an L shape and flows into the downstream side passage hole 64 on the cylinder block 17 side. The cooling water having flowed into the downstream passage hole 64 ascends substantially parallel to the cylinder center axis C1 at the right rear of the cylinder block 17 and is introduced into the water jacket 50. The cooling water introduced into the water jacket 50 flows in the water jacket 50 to remove the heat of the cylinder block 17 and the cylinder head 18, and is discharged to the external radiator side through a discharge passage (not shown).

As described above, in the cooling passage structure of the engine E employed in the power unit PU of the present embodiment, the cooling water discharged from the discharge port 59 of the water pump 51 is at the lower end position of the cylinder block 17 near the rear The cooling water flows into the water jacket 50 through the upstream passage hole 63 of the cylinder block 17 and rises substantially parallel to the cylinder center axis C1. Therefore, the cooling water can be efficiently supplied to the entire area in the cylinder block 17 while adopting an engine structure in which the cylinder block 17 is inclined forward and upward with respect to the crankcase 11. Therefore, since it is not necessary to use a large water pump, enlargement of the engine E can be avoided.

That is, since the introduction passage 62 connecting the discharge port 59 and the water jacket 50 rises linearly without being bent in a complicated manner at a position near the rear of the cylinder block 17, the flow resistance of the cooling water becomes small. Since the cooling water is introduced to the water jacket 50 from the lower end side of the front inclined cylinder block 17 near the rear, the cooling water flows efficiently in the entire area within the water jacket 50. Therefore, from these things, the cooling efficiency of the cylinder block 17 by a cooling water improves.

Further, in the cooling structure of the engine E according to the present embodiment, the expansion portion 50b which is expanded in the radial direction outward is substantially formed on the substantially annular base portion 50a centered on the cylinder center axis C1 of the water jacket 50. The downstream side passage hole 64 of the introduction passage 62 is connected to the extended portion 50b. Therefore, the downstream passage hole 64 of the introduction passage 62 may be substantially straight without bending while the introduction passage 62 is disposed radially outside the base portion 50a of the water jacket 50. it can. Therefore, with this structure, the flow resistance of the cooling water in the introduction passage 62 can be reduced, and the cooling efficiency of the cylinder block 17 by the cooling water can be further improved.

Further, in the cooling structure of the engine E according to the present embodiment, the position closer to the front and the position closer to the rear of the cylinder block 17 are fastened to the crankcase 11 by the stud bolt 20, and the discharge port 59 of the water pump 51 is the front It is arrange | positioned in area | region A1 pinched | interposed into the axial extension position of the stud bolt 20 of the side, and the axial extension position of the stud bolt 20 of the rear side. Therefore, the distance between the introduction passage 62 connected to the discharge port 59 and the base portion 50 a of the water jacket 50 can be further reduced. Therefore, since the distance from the discharge port 59 of the water pump 51 to the water jacket 50 becomes short, the cooling efficiency of the cylinder block 17 by the cooling water is improved.

Further, in the case of the present embodiment, not only the discharge port 59 of the water pump 51 but also the pump body (pump chamber 60) has an axially extending position of the stud bolt 20 on the front side and an axis of the stud bolt 20 on the rear side. The distance from the pump main body of the water pump 51 to the water jacket 50 is shortened because the water pump 50 is disposed in the area A1 sandwiched by the extending positions in the direction. Therefore, the flow resistance of the cooling water can be further reduced, and the cooling efficiency of the cylinder block 17 can be further improved.

Further, in the cooling structure of the engine E according to the present embodiment, a part of the casing 53 of the water pump 51 is integrally formed on the crank cover 30 and a portion of the casing 53 where the discharge port 59 is formed ( The discharge portion 53 a) is formed so as to be fitted into the recess 65 on the right side surface of the crankcase 11. For this reason, the discharge port 59 of the water pump 51 enters into the crankcase 11 side, and the discharge port 59 can be brought closer to the position directly below the water jacket 50 of the cylinder block 17 accordingly. Therefore, the cooling efficiency of the cylinder block 17 can be further improved by this.

Further, in the cooling structure of the engine E according to the present embodiment, the outer end face of the casing 53 of the water pump 51 is closed by the pump cover 54, and the connection passage 61 in the casing 53 faces the discharge port 59. Since the side is formed to be deep, the passage cross-sectional area of the connection passage 61 directed to the discharge port 59 can be secured sufficiently large on the crank cover 30 side. For this reason, there is no need to provide an outwardly bulging portion on the pump cover 54 side in order to secure the passage cross-sectional area of the connection passage 61. Therefore, since the pump cover 54 does not bulge outward, the water pump 51 can be miniaturized, and hence the entire engine E can be miniaturized.

Further, in the present embodiment, the cooling water introduction passage 62 formed across the crankcase 11 and the cylinder block 17 is outside the oil supply passage 33 formed between the joint surfaces of the crankcase 11 and the cylinder block 17. Therefore, the oil supply passage 33 can be shortened by arranging the oil supply passage 33 closer to the cylinder bore 17a. Therefore, since the flow path resistance of the oil in the oil supply path 33 can be reduced, the oil pump 32 can be miniaturized.

Furthermore, the cylinder block 17 of the present embodiment is entirely formed as a cast part, and the water jacket 50 and the downstream passage hole 64 connected to the water jacket 50 are formed by casting. Therefore, post-processing such as cutting after forming the cylinder block 17 by casting can be further reduced. For this reason, the number of processing steps of the cylinder block 17 can be reduced, and the manufacturing cost can be reduced.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, in the above embodiment, a spiral pump is employed as the water pump, but the water pump is not limited to the spiral and may be of another type.
Further, a vehicle equipped with the above power unit may be a three-wheeled vehicle (including a front two-wheeled vehicle and a rear two-wheeled vehicle as well as a front two-wheeled vehicle and a rear two-wheeled vehicle) or a four-wheeled vehicle.

DESCRIPTION OF SYMBOLS 10 ... Crankshaft 11 ... Crankcase 16 ... Piston 17 ... Cylinder block 20 ... Stud bolt (fastening member)
33: Oil supply passage 50: Water jacket (peripheral wall cooling passage)
50a ... base part 50b ... extended part 51 ... water pump 52 ... impeller (pump operation part)
53 ... casing portion 54 ... pump cover 59 ... discharge port 60 ... pump chamber (pump body portion)
61 ... connection passage 62 ... introduction passage 63 ... upstream passage hole 64 ... downstream passage hole 65 ... recess C1 ... cylinder center axis E ... engine.

Claims

A crankcase rotatably supporting a crankshaft;
A cylinder block having a peripheral wall cooling passage which is forwardly inclined to the upper front in a side view and is coupled to the crankcase and slidably accommodates a piston and allows cooling water to flow therethrough;
A water pump attached to the crankcase for discharging cooling water;
And an introduction passage of cooling water connecting the discharge port of the water pump and the peripheral wall cooling passage;
The discharge port of the water pump is disposed opposite to a position near the rear of the cylinder block of the crankcase,
The introduction passage extends from the discharge port substantially in parallel to a cylinder center axis of the cylinder block and is connected to the peripheral wall cooling passage in a side view of the engine, and the wall of the crankcase and the cylinder block Engine cooling passage structure formed inside.
The peripheral wall cooling passage has a substantially annular base portion centered on the cylinder center axis, and an expanded portion whose volume is expanded radially outward from the base portion at a position connected to the introduction passage; The cooling passage structure of an engine according to claim 1, comprising:
The cylinder block is fixed to the crankcase by a fastening member at a position near the front of the cylinder block in a side view of the engine.
The cylinder block is fixed to the crankcase by a fastening member at a position near the rear of the cylinder block in a side view of the engine.
A region where the discharge port of the water pump is sandwiched between an axial extension position of the fastening member near the front of the cylinder block and an axial extension position of the fastening member near the rear of the cylinder block The cooling passage structure of an engine according to claim 1 or 2, which is disposed in
The pump body portion of the water pump is sandwiched between an axial extension position of the fastening member near the front of the cylinder block and an axial extension position of the fastening member near the rear of the cylinder block The engine cooling passage structure according to claim 3, which is disposed in the area.
The water pump is integrally formed with a crank cover that partially covers a side of the crankcase and a part of a casing portion that accommodates a pump operation portion.
The engine cooling device according to any one of claims 1 to 4, wherein a portion of the crank cover on which the discharge port of the casing portion is formed is formed to protrude toward a concave portion on a side surface of the crankcase. Passage structure.
An axial end face of the casing portion of the water pump opposite to the crankcase is closed by a pump cover;
The engine cooling passage structure according to claim 5, wherein a connection passage connected to the discharge port in the casing portion is formed such that the crankcase side becomes deeper toward the discharge port side.
An oil supply passage is formed in the cylinder block from the front area to the rear area of the cylinder block at a joint surface with the crankcase.
The engine cooling passage structure according to any one of claims 1 to 6, wherein the introduction passage of the cooling water is formed to pass through the outside of the oil supply passage in the cylinder block.
The cylinder block is a cast part,
The engine according to any one of claims 1 to 7, wherein the downstream side passage hole which constitutes a part of the introduction passage on the cylinder block side and the peripheral wall cooling passage of the cylinder block are formed by casting. Cooling passage structure.