ENGINE AND VEHICLE

Description

[TECHNICAL FIELD]

[0001] The present invention relates to an engine, and a vehicle comprising the same.

[BACKGROUND]

[0002] Conventionally, an engine functions normally through lubrication, cooling, cleaning, etc. with oil circulating inside the engine. A system of circulating the oil includes a wet sump system and a dry sump system. For example, JP 5330052 B2 describes an engine employing the dry sump system. In this engine, oil dripping down to the bottom of a crankcase is sucked up by a scavenge pump and then stored in an oil reservoir chamber. Then, a feed pump supplies the oil from the oil reservoir chamber to each part inside the engine.

[0003] The engine known from US 2004/108166 A1 is deemed to be the closest prior art and comprises a cylinder, a crankcase connected thereto, a crankshaft arranged therein, a piston and a connecting rod connecting the piston to the crankshaft. An oil pan is provided at the bottom of the crank chamber from which the oil can be jetted by a recovery pump into an oil tank chamber. When viewed in a direction perpendicular to the axis of the cylinder and to the crank axis, this oil tank chamber overlaps with the crankshaft.

[0004] The disclosure of US 2006/005799 A1 is directed to an engine included in a saddle type vehicle, wherein respective centers of gravity of a crank shaft, a balancer shaft and a cylinder are positioned close to one another such that the mass can be centralized. An axis of the cylinder is offset in a rearward direction of the vehicle, i. e. opposite to the offset of the balance shaft.

[SUMMARY]

[TECHNICAL PROBLEM]

[0005] According to each of the wet sump system and the dry sump system, to prevent the occurrence of malfunction of an engine reliably due to oil shortage, the oil of a sufficient amount is required to be stored in the engine. However, trying to ensure a large reservoir capacity for the oil causes a problem of size increase of the engine.

[0006] The present invention has been made in view of the foregoing problem, and is intended to provide an engine ensuring a large reservoir capacity for oil while limiting size increase.

[SOLUTION TO PROBLEM]

[0007] According to the present invention the above problem is solved by an engine having the features of claim 1, and a vehicle having the features of claim 5. Particular embodiments are defined in the dependent claims.

[0008] An engine according to the present invention comprises: a cylinder; a crankcase connected to the cylinder; a crankshaft; a piston configured to make reciprocating motion in the cylinder; the crankshaft being connected via the connecting rod to the piston, and being configured to rotate about a crank axis in conjunction with the reciprocating motion of the piston, at least a part of the crankshaft being arranged in the crankcase; an oil pan provided in the crankcase; a reservoir part provided in the crankcase and storing oil; a scavenge pump that feeds the oil from the oil pan to the reservoir part; and a balance shaft arranged between at least the part of the reservoir part and the crankshaft and being configured to rotate in conjunction with the crankshaft, wherein in an offset direction orthogonal to each of an axis of the cylinder and the crank axis, the crank axis is located on one side of the axis of the cylinder, at least a part of the reservoir part is located on the other side of the axis of the cylinder in the offset direction and overlaps the crankshaft as viewed from the offset direction, at least the part of the reservoir part includes a first reservoir chamber and a second reservoir chamber arranged in an axis direction of the balance shaft and oil is stored in the interior of each of the first reservoir chamber and the second reservoir chamber, a weight of the balance shaft is located between both ends of the second reservoir chamber in the axis direction of the balance shaft, the first reservoir chamber includes a projecting part projecting toward the balance shaft further than the second reservoir chamber in a normal direction normal to the axis direction of the balance shaft, and at least a part of the projecting part overlaps a rotational locus of the weight of the balance shaft as viewed from the axis direction of the balance shaft.

[0009] In the present invention having the foregoing structure, the crank axis is located on the one side of the axis of the cylinder, thereby ensuring space on the other side of the axis of the cylinder. This space is used effectively by arranging at least the part of the reservoir part on the other side of the axis of the cylinder in such a manner that at least the part of the reservoir part overlaps the crankshaft as viewed from the offset direction. This makes it possible to limit size increase of the engine while ensuring a large reservoir capacity for the oil.

[0010] Additionally, in the present invention, such result is achieved effectively by taking advantage of the feature of the dry sump system. More specifically, in a wet sump, the oil is to be stored in the oil pan itself provided at the bottom of the crankcase. Hence, in order to avoid dip of the crankshaft in the oil, storing the oil of a large amount is prohibited. By contrast, in the present invention, the dry sump system of feeding the oil from the oil pan to the reservoir part is employed. This makes it possible to ensure a large reservoir capacity for the oil as described above while avoiding dip of the crankshaft in the oil.

[0011] The engine according to the present invention further allows the arrangement of the balance shaft while ensuring a reservoir capacity for the oil on the other side of the axis of the cylinder. Furthermore, this engine makes it possible to store the oil of a larger amount while preventing interference between the reservoir part and the balance shaft.

[0012] The engine may further comprise a transmission arranged in the crankcase, wherein the transmission is located on the one side of the axis of the cylinder in the offset direction. In this configuration, the transmission and at least the part of the reservoir part are on the sides opposite to each other across the axis of the cylinder. This makes it possible to ensure at least the part of the reservoir part without causing interference by the arrangement space for the transmission.

[0013] The engine may be configured so that as viewed from the axis direction of the balance shaft, at least the part of the reservoir part locates in the opposite direction of the oil pan across a line passing through the crank axis and a rotational axis of the balance shaft. This configuration contributes to ensuring of a large reservoir capacity for the oil.

[0014] The engine may be configured so that the crankcase includes an exterior wall forming an exterior wall surface, and at least a part of a wall surface of the reservoir part is configured by the exterior wall surface of the exterior wall. By doing so, a large reservoir capacity for the oil can be ensured through effective use of a capacity inside the crankcase.

[0015] A vehicle according to the present invention comprises the foregoing engine and a wheel to be driven by the engine. This makes it possible to limit size increase of the engine while ensuring a large reservoir capacity for the oil.

[ADVANTAGEOUS EFFECTS OF INVENTION]

[0016]  The present invention is capable of limiting size increase of an engine while ensuring a large reservoir capacity for oil.

[BRIEF DESCRIPTION OF DRAWINGS]

[0017] 

Fig. 1 is a side view showing a motorcycle corresponding to an example of a straddled vehicle equipped with an engine according to the present invention.

Fig. 2 is a partial cross-sectional view showing the internal configuration of an engine taken at a substantially central cross section.

Fig. 3 is a partial cross-sectional view showing the internal configuration of the engine taken at a cross section external to the cross-section of Fig. 2.

Fig. 4 is a partial cross-sectional view of the engine taken along a cutting line IV-IV shown in Fig. 3.

Fig. 5 is a block diagram showing an example of an oil circulation system provided in the engine.

Fig. 6 shows the arrangement of a reservoir part and a crankshaft as viewed from the other side toward one side in an offset direction.

Fig. 7 is a partial cross-sectional view showing the arrangement of the reservoir part, the crankshaft, and a balance shaft.

[DESCRIPTION OF EMBODIMENTS]

[0018] Fig. 1 is a side view showing a motorcycle corresponding to an example of a straddled vehicle equipped with an engine according to the present invention. A motorcycle 1 shown in Fig. 1 is so-called an off-road type vehicle. Meanwhile, in addition to this type, the straddled vehicle includes motorcycles of an on-road type, a scooter-type, a so-called moped-type, etc. The vehicle according to the present invention includes not only the straddled vehicle but also includes an all terrain vehicle (ATV), a four-wheel buggy, etc.

[0019] In this description, front, rear, left, and right means a front side, a rear side, a left side, and a right side respectively viewed from a passenger on a seat 10. A front-rear direction Dp, a front side Df in the front-rear direction Dp, a rear side Db in the front-rear direction Dp, a vehicle-width direction Dw, and a vertical direction Dv are shown, where appropriate. Each of the front-rear direction Dp and the vehicle-width direction Dw is a horizontal direction. The front-rear direction Dp, the vehicle-width direction Dw, and the vertical direction Dv are orthogonal to each other.

[0020] The motorcycle 1 includes a vehicle body frame 2. The vehicle body frame 2 has a head pipe 21, a main frame 22, a tank rail 23, a seat rail, a back stay 25, a down frame 26, etc. The head pipe 21 is arranged at an end portion of the vehicle body frame 2 on the front side Df. The main frame 22 extends from the head pipe 21 toward the rear side Db and is bent downward. The tank rail 23 is arranged between the head pipe 21 and the main frame 22. A fuel tank 31 is attached to the tank rail 23. The seat rail extends from the main frame 22 toward the rear side Db. The seat 10 is attached to the seat rail. An end portion of the seat rail on the rear side Db is connected to the main frame 22 with the back stay 25. The down frame 26 extends downward from the head pipe 21 and is bent toward the rear side Db. Respective end portions of the down frame 26 and the main frame 22 on the rear side Db are connected to each other.

[0021] A steering shaft not shown in the drawings is rotatably inserted into the head pipe 21. The steering shaft has an upper end portion to which a handle 32 is attached. A front fork 33 fork 33 extending diagonally downward toward the front side Df is attached to the steering shaft. The front fork 33 has a lower end portion to which a front wheel 34 is attached rotatably.

[0022] A pivot shaft 221 is attached to an end portion of the main frame 22 on the rear side Db. A rear arm 35 extends from the pivot shaft 221 toward the rear side Db. While the rear arm 35 is supported by the pivot shaft 221 so as to be pivotable upward and downward (vertical direction Dv) about the pivot shaft 221, the rear arm 35 is attached to the main frame 22 via a gear suspension 36. A rear wheel 37 is rotatably attached to an end portion of the rear arm 35 on the rear side Db.

[0023] An engine 5 is mounted to the vehicle body frame 2 in a region surrounded by the main frame 22 and the down frame 26. The engine 5 rotates the rear wheel 37 via a secondary speed reducer not shown in the drawings. The secondary speed reducer can use any one of a chain-driven system, a shaft-driven system, and a belt-driven system.

[0024] Fig. 2 is a partial cross-sectional view showing the internal configuration of an engine taken at a substantially central cross section. Fig. 3 is a partial cross-sectional view showing the internal configuration of the engine taken at a cross section external to the cross-section of Fig. 2. Fig. 4 is a partial cross-sectional view of the engine taken along a cutting line IV-IV shown in Fig. 3. The engine 5 includes a cylinder block 51, a cylinder head 52 attached to the upper end of the cylinder block 51, and a crankcase 53 attached to the lower end of the cylinder block 51. The cylinder block 51 has a head mating surface 51a as a surface of mating to the cylinder head 52. The cylinder head 52 has a cylinder mating surface 52a as a surface of mating to the cylinder block 51. With the head mating surface 51a of the cylinder block 51 and the cylinder mating surface 52a of the cylinder head 52 in mating contact with each other, the cylinder block 51 and the cylinder head 52 are attached to each other. The cylinder block 51 has an outer peripheral surface provided with a flange 51b. The flange 51b has a crank mating surface 51c as a surface of mating to the crankcase 53. The crankcase 53 has a cylinder mating surface 53c as a surface of mating to the cylinder block 51. With the crank mating surface 51c of the cylinder block 51 and the cylinder mating surface 53c of the crankcase 53 in mating contact with each other, the cylinder block 51 and the crankcase 53 are attached to each other.

[0025] The engine 5 is a single-cylinder type engine with a single cylinder 511 provided at the cylinder block 51. A piston 512 is arranged in the cylinder 511. The piston 512 can make reciprocating motion in the cylinder 511. The cylinder 511 is inclined rearward. More specifically, an axis Lc of the cylinder 511 is inclined toward the rear side Db with respect to the vertical direction Dv. In other words, the axis Lc of the cylinder 511 is inclined further toward the rear side Db at a higher position. The axis Lc of the cylinder 511 can be determined as a virtual line passing through the center of a bore in the cylinder 511 and extending parallel to the direction of the stroke of the piston 512, for example.

[0026] The cylinder head 52 includes an intake port 522 communicating with a combustion chamber defined between the cylinder head 52 and the upper end surface of the piston 512, and an intake valve 523 for opening and closing the intake port 522 for the combustion chamber. The intake valve 523 is biased by a valve spring 524 to be located at a position of closing the intake port 522. Rotating a camshaft 525 contacting with the upper end of the intake valve 523 allows opening and closing of the intake valve 523. The cylinder head 52 includes an exhaust port 526 communicating with the combustion chamber, and an exhaust valve 527 for opening and closing the exhaust port 526 for the combustion chamber. The exhaust valve 527 is biased by a valve spring 528 to be located at a position of closing the exhaust port 526. Rotating a camshaft 529 contacting with the upper end of the exhaust valve 527 allows opening and closing of the exhaust valve 527. In this way, the engine 5 has an intake and exhaust valve mechanism of a double over head camshaft (DOHC) type with the camshafts 525 and 529 provided on an intake side and an exhaust side respectively. The engine 5 has a multivalve mechanism with multiple (two) intake valves 523 and multiple (two) exhaust valves 527.

[0027] The crankcase 53 includes a housing part 54 housing the mechanical structures of the engine 5, and a reservoir part 55 (oil tank) storing engine oil circulating in the engine 5. The housing part 54 and the reservoir part 55 are separated by a partition 56. Further, the housing part 54 includes a crank chamber 541 inside.

[0028] The crank chamber 541 communicates with the cylinder 511 and houses a crankshaft 61 arranged parallel to the vehicle-width direction Dw. The crankshaft 61 includes a crank journal 611 supported by the crankcase 53 so as to be rotatable about a crank axis C61 parallel to the vehicle-width direction Dw, and a crank pin 612 eccentric with respect to the crank axis C61. The crank pin 612 is connected to the piston 512 with a connecting rod 62. The crankshaft 61 rotates about a crank axis C61 in conjunction with the reciprocating motion of the piston 512. The crankshaft 61 includes a counterweight 613 eccentric with respect to the crank axis C61 toward the opposite side of the crank pin 612. The counterweight 613 contributes to reduction of vibration.

[0029] The crank chamber 541 houses a balance shaft 63 arranged parallel to the vehicle-width direction Dw. The balance shaft 63 is supported by the crankcase 53 so as to be rotatable about a balancer axis C63 parallel to the vehicle-width direction Dw, and includes a weight 631 eccentric with respect to the balancer axis C63. The balance shaft 63 rotates in conjunction with the rotation of the crankshaft 61 to reduce vibration of the crankshaft 61.

[0030] A primary drive gear 614 is attached to the crankshaft 61 to be coaxial with the crankshaft 61. The primary drive gear 614 rotates together with the crankshaft 61 about the crank axis C61. Further, a balancer gear 632 is attached to the balance shaft 63 to be coaxial with the balance shaft 63. The balance shaft 63 rotates together with the balancer gear 632 about the balancer axis C63. The primary drive gear 614 and the balancer gear 632 are engaged with each other, the reduced rotation of the crankshaft 61 is transmitted to the balance shaft 63.

[0031] The engine 5 includes a generator 64 that generates power from the rotary motion of the crankshaft 61. The generator 64 includes a flywheel 641 and a stator coil 642 arranged inside the flywheel 641. The flywheel 641 is attached to the crankshaft 61 to be coaxial with the crankshaft 61, and rotatable about the crank axis C61 together with the crankshaft 61. The flywheel 641 includes N-pole magnets and S-pole magnets aligned alternately to surround the stator coil 642 from outside. The generator 64 generates power in response to electromagnetic induction generated between the magnets and the stator coil 642 by the rotation of the flywheel 641.

[0032] The crank chamber 541 further houses a clutch mechanism 65 and a transmission 66. As shown in Fig. 4, an end portion of the crankcase 53 in the vehicle-width direction Dw forms a clutch box 532 covering the clutch mechanism 65 and projects further than the cylinder 511 in the vehicle-width direction Dw. The clutch mechanism 65 includes a clutch housing 651 rotatable about a main axis C67 parallel to the vehicle-width direction Dw. The clutch housing 65 has an outer periphery provided with a primary driven gear 652 centered on a main axis. The primary drive gear 614 and the primary driven gear 652 are engaged with each other to form a primary speed reducer of reducing the rotation of the crankshaft 61 and transmitting it to the clutch housing 651.

[0033] In the clutch mechanism 65, a clutch boss 653 rotatable about the main axis C67 is arranged inside the clutch housing 651. Further, friction plates 654 to rotate together with the clutch housing 651 and clutch plates 655 to rotate together with the clutch boss 653 are aligned alternately. The clutch mechanism 65 further includes a pressure part 656 biased toward the clutch boss 653 by the elastic force of a clutch spring. The clutch mechanism 65 presses the friction plates 654 and the clutch plates 655 to the clutch boss 653 by the pressure part 656 to allow transmission of the rotation of the clutch housing 651 to the clutch boss 653. In another case, the clutch mechanism 65 moves pressure part 656 toward the opposite side of the clutch boss 653 against the elastic force of the clutch spring to allow interruption of transmission of the rotation from the clutch housing 651 to the clutch boss 653.

[0034] A main shaft 67 of the transmission 66 is attached to the clutch boss 653. Thus, the clutch mechanism 65 can make transmitting motion of transmitting power from the crankshaft 61 to the main shaft 67 and interrupting motion of interrupting transmission of the power from the crankshaft 61 to the main shaft 67 selectively.

[0035] The transmission 66 includes the main shaft 67 and a drive shaft 68 both arranged parallel to the vehicle-width direction Dw. The main shaft 67 is supported by the crankcase 53 so as to be rotatable about the main axis C67. The drive shaft 68 is supported by the crankcase 53 so as to be rotatable about a drive axis C68 parallel to the vehicle-width direction Dw. The main shaft 67 is provided with a plurality of gears 671 forming a part of the transmission 66. Thus, the weight of the main shaft 67 including the plurality of gears 671 is generally larger than that of the foregoing balance shaft 63. The main shaft 67 is further provided with a shift fork 672 for causing the gears 671 to slide toward the axis direction of the main shaft 67 (vehicle-width direction Dw). The drive shaft 68 is provided with a plurality of gears 681, and a shift fork 682 for causing the gears 681 to slide toward the axis direction of the drive shaft 68 (vehicle-width direction Dw). A shift drum 661 to rotate in response to driver's operation is provided for the shift forks 672 and 682. The shift forks 672 and 682 move the gear 671 and the gear 681 respectively located at their positions corresponding to the rotation angle of the shift drum 661. In this way, the transmission 66 transmits the rotation of the main shaft 67 to the drive shaft 68 at a transmission gear ratio responsive to the driver's operation. The rotation of the drive shaft 68 is transmitted to the rear wheel 37 by the secondary speed reducer.

[0036] As described above, the engine oil is cyclically supplied to the crank chamber 54. The bottom of the crank chamber 541 functions as an oil pan 544 to receive the engine oil dripping by its own weight.

[0037] The reservoir part 55 stores the engine oil in a reservoir chamber 551 inside the reservoir part 55. The reservoir chamber 551 is arranged on the front side Df of the crank chamber 541 and overlaps the crank chamber 541 at least partially in a front view from the front side Df. The engine oil has a composition containing mineral-based oil, chemically synthesized oil, or partially chemically synthesized oil as base oil, and an adder added to the base oil. The engine oil is circulated in the engine 5 by a pump (scavenge pump or feed pump). This pump is driven by using the rotation of the crankshaft 61. More specifically, a pump gear (not shown in the drawings) engaging with the primary drive gear 614 is attached to the pump to be coaxial with the pump. The primary drive gear 614 and the pump gear transmit the rotation of the crankshaft 61 to the pump.

[0038] The following describes layout in the engine 5 in detail taken in a side view from the axis direction of the crankshaft 61 (namely, from the vehicle-width direction Dw) shown in Fig. 2. The crankshaft 61, the balance shaft 63, the main shaft 67, and the drive shaft 68 are arranged parallel to each other. As shown in Fig. 2, the crankshaft 61 is offset rearward from the axis Lc of the cylinder 511. More specifically, a virtual half line Lh starting from the crank axis C61 of the crankshaft 61 and extending parallel to the axis Lc of the cylinder 511 toward the cylinder 511 is located rearward of the axis Lc of the cylinder 511. From a different viewpoint, in an offset direction Do normal to each of the axis Lc of the cylinder 511 and the crank axis C61, the axis Lc of the cylinder 511 is located closer to the balance shaft 63 than the virtual half line Lh. In this way, the crank axis C61 (or virtual half line Lh) is located on one side Do1 of the offset direction Do in respect with the axis Lc of the cylinder 511 , and the balance shaft 63 is located on the other side Do2 of the offset direction Do in respect with the axis Lc of the cylinder 511. The other side Do2 is opposite to the one side Do1.

[0039] The balance shaft 63 is arranged on the opposite side of the main shaft 67 across the virtual half line Lh. "The balance shaft 63 being arranged on the opposite side of the main shaft 67 across the virtual half line Lh" has the same meaning as the balance shaft 63 being arranged on the opposite side of the main shaft 67 across a virtual line passing through the crank axis C61 and extending parallel to the axis Lc of the cylinder 511. An angle θ1 (0° < θ1 < 90°) is provided between the virtual half line Lh and a first virtual line segment L1 between the main axis C67 and the crank axis C61. Further, an angle θ2 (0° < θ2) is provided between the virtual half line Lh and a second virtual line segment L2 between the balancer axis C63 and the crank axis C61. The crankshaft 61, the balance shaft 63, and the main shaft 67 are arranged so as to fulfill a relationship of angle θ1 < angle θ2.

[0040] A line segment and a half line form a major angle (an angle greater than 180 degrees) and a minor angle (an angle less than 180 degrees), and an angle therebetween described herein means the minor angle. Specifically, all the angle θ1 and the angle θ2 are smaller than 180 degrees. The axis Lc, the virtual half line Lh, the first virtual line segment L1, and the second virtual line segment L2 mentioned herein are all normal to the axis direction of the crankshaft 61 (vehicle-width direction Dw).

[0041] In the engine 5 having the foregoing configuration, the respective masses of the main shaft 67 and the balance shaft 63 are distributed to the opposite sides of the virtual half line Lh starting from the crank axis C61 and extending parallel to the axis Lc of the cylinder 511 toward the cylinder 511. Hence, the arrangement of the main shaft 67 influences mass centralization. In this regard, in this embodiment, the main shaft 67 is arranged so as to fulfill the relationship of angle θ1 < angle θ2. More specifically, to encourage mass centralization, the main shaft 67 is arranged close to the virtual half line Lh starting from the crank axis C61 so as to fulfill this angular relationship. By doing so, mass centralization can be encouraged in the engine 5 provided with the main shaft 67, the crankshaft 61, and the balance shaft 63.

[0042] As shown in Fig. 2, a lower end portion of the reservoir part 55 is arranged below the crankshaft 61, and an upper end portion 55T of the reservoir part 55 (a portion above the lower end portion) is arranged on the other side Do2 of the crankshaft 61 in the offset direction Do. Accordingly, an upper end portion 551T of the reservoir chamber 551 provided in the upper end portion 55T of the reservoir part 55 also becomes located on the other side Do2 of the crankshaft 61 in the offset direction Do. The balance shaft 63 is arranged so as to be caught between the upper end portion 55T of the reservoir chamber 551 and the crankshaft 61 in the offset direction Do. The layout of the reservoir part 55, the crankshaft 61, the balance shaft 63, and the transmission 66 (main shaft 67, drive shaft 68) will be described in detail later by referring to Figs. 6 and 7.

[0043] An oil circulation system of circulating engine oil will be described next by referring to Fig. 5. Fig. 5 is a block diagram showing an example of an oil circulation system provided in the engine. Arrows in Fig. 5 show a direction in which the engine oil flows. The engine 5 includes a scavenge pump 91 to be driven by the rotation of a pump gear. The scavenge pump 91 is connected via a pipe T1 to the crank chamber 541. Thus, the engine oil dripping down to the oil pan 544 in the crank chamber 541 is sucked by the scavenge pump 91 and discharged from the crank chamber 541. At this time, the engine oil is filtered with a strainer 547 in the crank chamber 541 and then discharged toward the scavenge pump 91.

[0044] The scavenge pump 91 pumps the sucked engine oil to a pipe T2 communicating with the reservoir part 55. Thus, the engine oil fed from the scavenge pump 91 is returned to the reservoir part 55 via the pipe T2. In this way, the engine oil sucked from the crank chamber 541 by the scavenge pump 91 is stored into the reservoir part 55. The reservoir part 55 and the crank chamber 541 communicate with each other via a pipe, and the engine oil having overflowed the reservoir part 55 is discharged via the pipe to the crank chamber 541.

[0045] The engine 5 includes a feed pump 93 to be driven by the rotation of the pump gear. The feed pump 93 is connected to the reservoir part 55 via a pipe T4. Thus, the engine oil stored in the reservoir part 55 is sucked by the feed pump 93 and discharged from the reservoir part 55. At this time, the engine oil is filtered with a strainer 552 in the reservoir part 55 and then discharged toward the feed pump 93. The feed pump 93 is connected to a relief valve 94 via a pipe T5 and a pipe T6. If a pressure at the feed pump 93 exceeds a predetermined value, the relief valve 94 is actuated to discharge the engine oil from the feed pump 93 to the pipe T5. Then, the engine oil is returned to the feed pump 93 via the pipe T6

[0046] The feed pump 93 pumps the engine oil sucked from the reservoir part 55 to an oil cleaner 95 via a pipe T7. The oil cleaner 95 has an output side to which a pipe T8 and a pipe T9 are connected. The engine oil pumped to the oil cleaner 95 is cleaned by the oil cleaner 95, and then flows into the pipes T8 and T9.

[0047] The pipe T8 communicates with the crankshaft 61 in the crank chamber 541, and supplies the engine oil to each of the crank journal 611 on the right side and the crank pin 612 of the crankshaft 61. The pipe T9 supplies the engine oil to each of the piston 512 and the crank journal 611 on the left side, then extends toward the cylinder head 52 to supply the engine oil to the cam shafts 525 and 529.

[0048] The pipe T9 branches into a pipe T10 and a pipe T11. The pipe T10 supplies the engine oil to the main shaft 67, the primary driven gear 652, and the clutch mechanism 65 in this order. The pipe T11 supplies the engine oil to a mission shower and the drive shaft 68 in this order. The engine oil supplied to the mission shower is poured from the mission shower into the drive shaft 68.

[0049]  The layout of the reservoir part 55 inside the engine 5 will be described in detail next by referring to Fig. 2, and by further referring to Figs. 6 and 7. Fig. 6 shows the arrangement of a reservoir part and a crankshaft as viewed from the other side toward one side in an offset direction. Fig. 7 is a partial cross-sectional view showing the arrangement of the reservoir part, the crankshaft, and a balance shaft. Fig. 6 shows the crankshaft 61 in a state when the piston 512 is at a top dead center, and a part of the crankshaft 61 hidden by the reservoir part 55 is indicated by dashes. Fig. 7 shows arrangement in a top view determined when the weight 631 of the balance shaft 63 is closest to the front side Df, and also shows a rotational locus 631T of the weight 631 of the balance shaft 63 (specifically, a region where the weight 631 passes through during the weight 631 makes one turn). Fig. 7 shows a right side Dr and a left side DI in the vehicle-width direction Dw.

[0050] As described above, the upper end portion 55T of the reservoir part 55 and the upper end portion 551T of the reservoir chamber 551 in the reservoir part 55 are arranged on the other side Do2 of the crankshaft 61 in the offset direction Do. This makes the upper end portion 55T of the reservoir part 55 overlap the crankshaft 61 as viewed from the offset direction Do as shown in Fig. 6, so that a part of the crankshaft 61 is hidden by the upper end portion 55T of the reservoir part 55. More specifically, the crank journals 611 on the right side and the left side are entirely hidden by the upper end portion 55T of the reservoir part 55. While the piston 512 is at a top dead center, the counterweights 613 on the right side and the left side are entirely hidden by the upper end portion 55T of the reservoir part 55, the crank pin 612 is entirely hidden by the upper end portion 55T of the reservoir part 55, an upper end 615a of a crank arm 615 slightly projects from the upper end portion 55T of the reservoir part 55, and a part of the crank arm 615 other than the upper end 615a is hidden by the upper end portion 55T of the reservoir part 55. The foregoing relationship in terms of arrangement is viewed from the offset direction Do. Meanwhile, a relationship comparable to the relationship given in this description is fulfilled by arrangement viewed from the front-rear direction Dp (horizontal direction).

[0051] As shown in Fig. 7, the reservoir chamber 551 in the reservoir part 55 is separated by a partition 555 into a first reservoir chamber 553 and a second reservoir chamber 554. The first reservoir chamber 553 and the second reservoir chamber 554 are adjacent to each other in the vehicle-width direction Dw across the partition 555. In this way, in the reservoir part 55, the first reservoir chamber 553 and the second reservoir chamber 554 are arranged in the axis direction of the balance shaft 63, namely, in the vehicle-width direction Dw. Of the first reservoir chamber 553 and the second reservoir chamber 554, the first reservoir chamber 553 on the left side DI is provided with a projecting part 553J projecting toward the rear side Db (toward the balance shaft 63) from the second reservoir chamber 554 on the right side Dr. The first reservoir chamber 553 and the second reservoir chamber 554 are provided to extend the reservoir chamber 551 including the upper end portion 551T entirely and communicate with each other. This allows the engine oil to flow back and forth between the first reservoir chamber 553 and the second reservoir chamber 554.

[0052] The weight 631 of the balance shaft 63 is arranged as follows relative to the first reservoir chamber 553 and the second reservoir chamber 554. The rotational locus 631T of the weight 631 is located on the right side Dr of the projecting part 553J of the first reservoir chamber 553 in the vehicle-width direction Dw (namely, on the side of the second reservoir chamber 554). In the vehicle-width direction Dw, an end 631r and an end 6311 of the rotational locus 631T of the weight 631 are located between an end 554r and an end 554l of the second reservoir chamber 554. The rotational locus 631T of the weight 631 faces the projecting part 553J while being separated from the projecting part 553J in the vehicle-width direction Dw. In other words, an end 631f of the weight 631 on the front side Df is located on the front side Df of an end 553b of the projecting part 553J on the rear side Db. As viewed from the vehicle-width direction Dw, the projecting part 553J of the first reservoir chamber 553 and the rotational locus 631T of the weight 631 partially overlap each other.

[0053] As shown in Fig. 2, the reservoir part 55 is arranged so as to cross a virtual line I passing through the crank axis C61 and the balance shaft 63 (namely, a virtual line passing through the second virtual line segment L2). In other words, the reservoir part 55 is extended from the side of the oil pan 544 toward the opposite side of the oil pan 544 across the virtual line I. In this way, the reservoir part 55 is extended to such an extent that a part of the reservoir part 55 exists in the opposite direction of the oil pan 544 across the virtual line I.

[0054] The crankcase 53 includes an exterior wall 531 forming an exterior wall surface of the crankcase 53. The wall surface of the reservoir part 55 is configured by the exterior wall surface of the exterior wall 531. That is, the exterior wall 531 functions as a wall of the crankcase 53 and also functions as a wall of the reservoir part 55. In this way, a part of the wall of the crankcase 53 and a part of the wall of the reservoir part 55 are used in common.

[0055] In the foregoing engine 5, the crank axis C61 of the crankshaft 61 is located on the one side Do1 of the axis Lc of the cylinder 511, thereby ensuring space on the other side Do2 of the axis Lc of the cylinder 511. This space is used effectively by arranging the upper end portion 55T of the reservoir part 55 on the other side Do2 of the axis Lc of the cylinder 511 in such a manner that the upper end portion 55T overlaps the crankshaft 61 as viewed from the offset direction Do. This makes it possible to limit size increase of the engine 5 while ensuring a large reservoir capacity for the engine oil.

[0056] Additionally, in the foregoing engine 5, such result is achieved effectively by taking advantage of the feature of the dry sump system. More specifically, in a wet sump, the engine oil is to be stored in the oil pan 544 itself provided at the bottom of the crankcase 53. Hence, in order to avoid dip of the crankshaft 61 in the engine oil, storing the engine oil of a large amount is prohibited. By contrast, in the foregoing engine 5, the dry sump system of feeding the engine oil from the oil pan to the reservoir part 55 is employed. This makes it possible to ensure a large reservoir capacity for the engine oil as described above while avoiding dip of the crankshaft 61 in the engine oil.

[0057] As shown in Fig. 2, in the crankcase 53, the transmission 66 is arranged on the one side Do1 in the offset direction Do of the axis Lc of the cylinder 511. More specifically, the transmission 66 and the upper end portion 55T of the reservoir part 55 are on the sides opposite to each other across the axis Lc of the cylinder 511. This makes it possible to ensure the capacity of the upper end portion 55T of the reservoir part 55 without causing interference by the arrangement space for the transmission 66.

[0058] The balance shaft 63 that rotates in conjunction with the crankshaft 61 is provided between the upper end portion 55T of the reservoir part 55 and the crankshaft 61. More specifically, in the foregoing engine 5, the crankshaft 61 is located on the one side Do1 of the axis Lc of the cylinder 511 to ensure space on the other side Do2 of the axis Lc of the cylinder 511. This further allows the arrangement of the balance shaft 63 while ensuring a reservoir capacity for the engine oil on the other side Do2 of the axis Lc of the cylinder 511.

[0059]  The upper end portion 55T of the reservoir part 55 includes the first reservoir chamber 553 and the second reservoir chamber 554 arranged in the axis direction of the balance shaft 63, namely, in the vehicle-width direction Dw. The oil is stored in the interior of each of the first reservoir chamber 553 and the second reservoir chamber 554. In the vehicle-width direction Dw, the weight 631 of the balance shaft 63 is located between the both ends 554r and 554l of the second reservoir chamber 554. The first reservoir chamber 553 includes the projecting part 553J projecting toward the weight 631 further than the second reservoir chamber 554 in the front-rear direction Dp. A part of the projecting part 553J overlaps the rotational locus 631T of the weight 631 of the balance shaft 63 as viewed from the vehicle-width direction Dw. In this configuration, the projecting part 553J is provided at the first reservoir chamber 553 of the reservoir part 55. This makes it possible to store the engine oil of a larger amount while preventing interference between the reservoir part 55 and the balance shaft 63.

[0060] The reservoir part 55 is extended from the side of the oil pan 544 toward the opposite side of the oil pan 544 across the virtual line l passing through the crank axis C61 and the balance shaft 63. By doing so, a large reservoir capacity for the engine oil is ensured.

[0061] The crankcase 53 includes the exterior wall 531 forming the exterior wall surface. At least a part of the wall surface of the reservoir part 55 is configured by the exterior wall surface of the exterior wall 531. By doing so, a large reservoir capacity for the engine oil is ensured through effective use of a capacity inside the crankcase 53.

[0062] As described above, in the foregoing embodiment, the engine 5 corresponds to an example of an "engine" of the present invention. The cylinder 511 corresponds to an example of a "cylinder" of the present invention. The crankcase 53 corresponds to an example of a "crankcase" of the present invention. The exterior wall 531 corresponds to an example of an "exterior wall" of the present invention. The crankshaft 61 corresponds to an example of a "crankshaft" of the present invention. The crank axis C61 corresponds to an example of a "crank axis" of the present invention. The piston 512 corresponds to an example of a "piston" of the present invention. The connecting rod 62 corresponds to an example of a "connecting rod" of the present invention. The oil pan 544 corresponds to an example of an "oil pan" of the present invention. The reservoir part 55 corresponds to an example of a "reservoir part" of the present invention. The first reservoir chamber 553 corresponds to an example of a "first reservoir chamber" of the present invention. The second reservoir chamber 554 corresponds to an example of a "second reservoir chamber" of the present invention. The projecting part 553J corresponds to an example of a "projecting part" of the present invention. The scavenge pump 91 corresponds to an example of a "scavenge pump" of the present invention. The offset direction Do corresponds to an example of an "offset direction" of the present invention. The one side Do1 corresponds to an example of "one side" of the present invention. The other side Do2 corresponds to an example of "the other side" of the present invention. The balance shaft 63 corresponds to an example of a "balance shaft" of the present invention. The weight 631 corresponds to an example of a "weight" of the present invention. The rotational locus 631T corresponds to an example of a "rotational locus" of the present invention. The transmission 66 corresponds to an example of a "transmission" of the present invention. The motorcycle 1 corresponds to an example of a "vehicle" of the present invention. The front wheel 34 and the rear wheel 37 correspond to examples of a "wheel" of the present invention.

[0063] The present invention is not limited to the foregoing embodiment. Various changes other than those described above are applicable within a range not deviating from the substance of the claims. For example, the configuration of the reservoir part 55 may be changed, if appropriate. More specifically, the partition 555 is not always required to be provided between the first reservoir chamber 553 and the second reservoir chamber 554. Additionally, the projecting part 553J is not always required to be provided.

[0064] A degree of overlap of the reservoir part 55 or the reservoir chamber 551 with the crankshaft 61 may be changed, if appropriate. Additionally, the balance shaft 63 is not always required to be provided between the upper end portion 55T of the reservoir part 55 and the crankshaft 61.

[0065] For example, in the foregoing description, the engine 5 described as an example is a single-cylinder type engine with the single cylinder 511 provided at the cylinder block 51. Alternatively, the number of the cylinders 511 of the engine 5 is not limited to one but the engine 5 may include two or more cylinders 511.

[0066] The intake and exhaust valve mechanism provided at the engine 5 is not limited to a mechanism of the foregoing DOHC type but it may also be a mechanism of a different type such as a single over head camshaft (SOHC). Further, a system for driving the intake valve 523 and the exhaust valve 527 is not limited to the foregoing direct-drive system but it may also be a different system such as a rocker arm system.

[0067] The posture of the cylinder 511 is not limited to the foregoing rearward tilted posture but it may also be a forward tilted posture or an upright posture.

[0068]  The specific configuration of the crankcase 53 can be changed, if appropriate. Thus, the crankcase 53 is not always required to include the reservoir part 55 integrally, for example.

[0069] The position or angle for attaching the engine 5 to the vehicle body frame 2 is not limited to that described in the foregoing example but can be changed, if appropriate.

[INDUSTRIAL APPLICABILITY]

[0070] The present invention is applicable to an engine using engine oil, and to every type of vehicle comprising the engine.

[REFERENCE SIGNS LIST]

[0071] 

1

motorcycle (Vehicle)

34

front wheel (wheel)

37

rear wheel (wheel)

5

engine

511

cylinder

512

piston

53

crankcase

531

exterior wall

544

oil pan

55

reservoir part

553

first reservoir chamber

553J

projecting part

554

second reservoir chamber

61

crankshaft

62

connecting rod

63

balance shaft

631

weight

631T

rotational locus

91

CR scavenge pump

C61

crank axis

Do

offset direction

Do1

one side

Do2

the other side

Claims

1. An engine (5), comprising:

a cylinder (511);

a crankcase (53) connected to the cylinder (511);

a crankshaft (61);

a connecting rod (62);

a piston (512) configured to make reciprocating motion in the cylinder (511);

the crankshaft (61) being connected via the connecting rod (62) to the piston (512), and being configured to rotate about a crank axis (C61) in conjunction with the reciprocating motion of the piston (512), at least a part of the crankshaft (61) being arranged in the crankcase (53);

an oil pan (544) provided in the crankcase (53);

a reservoir part (55) provided in the crankcase (53) and storing oil;

a scavenge pump (91) that feeds the oil from the oil pan (544) to the reservoir part (55); and

a balance shaft (63) arranged between at least the part of the reservoir part (55) and the crankshaft (61) and being configured to rotate in conjunction with the crankshaft (61),

characterized in that

in an offset direction (Do) orthogonal to each of an axis (Lc) of the cylinder (511) and the crank axis (C61), the crank axis (C61) is located on one side (Do1) of the axis (Lc) of the cylinder (511),

at least a part of the reservoir part (55) is located on the other side (Do2) of the axis (Lc) of the cylinder (511) in the offset direction (Do) and overlaps the crankshaft (61) as viewed from the offset direction (Do),

at least the part of the reservoir part (55) includes a first reservoir chamber (553) and a second reservoir chamber (554) arranged in an axis direction of the balance shaft (63) and oil is stored in the interior of each of the first reservoir chamber (553) and the second reservoir chamber (554),

a weight (631) of the balance shaft (63) is located between both ends of the second reservoir chamber (554) in the axis direction of the balance shaft (63),

the first reservoir chamber (553) includes a projecting part (553J) projecting toward the balance shaft (63) further than the second reservoir chamber (554) in a normal direction normal to the axis direction of the balance shaft (63), and

at least a part of the projecting part (553J) overlaps a rotational locus (631T) of the weight (631) of the balance shaft (63) as viewed from the axis direction of the balance shaft (63).

2. The engine (5) according to claim 1, further comprising a transmission (66) arranged in the crankcase (53), wherein
the transmission (66) is located on the one side (Do1) of the axis (Lc) of the cylinder (511) in the offset direction (Do).

3. The engine (5) according to claim 1 or 2, wherein
as viewed from the axis direction of the balance shaft (63), at least the part of the reservoir part (55) locates in the opposite direction of the oil pan (544) across a line (I) passing through the crank axis (C61) and a rotational axis (C63) of the balance shaft (63).

4. The engine (5) according to any one of claims 1 to 3, wherein
the crankcase (53) includes an exterior wall (531) forming an exterior wall surface, and at least a part of a wall surface of the reservoir part (55) is configured by the exterior wall surface of the exterior wall (531).

5. A vehicle (1), comprising:

the engine (5) according to any one of claims 1 to 4; and

a wheel (37) to be driven by the engine (5).

Ansprüche

1. Motor (5), der umfasst:

einen Zylinder (511);

ein Kurbelgehäuse (53), das mit dem Zylinder (511) verbunden ist;

eine Kurbelwelle (61);

eine Pleuelstange (62);

einen Kolben (512), der so ausgeführt ist, dass er sich in dem Zylinder (511) hin- und herbewegt;

wobei die Kurbelwelle (61) über die Pleuelstange (62) mit dem Kolben (512) verbunden und so ausgeführt ist, dass sie sich zusammen mit der Hin- und Herbewegung des Kolbens (512) um eine Kurbel-Achse (C61) herum dreht, wobei wenigstens ein Teil der Kurbelwelle (61) in dem Kurbelgehäuse (53) angeordnet ist;

eine Ölwanne (544), die in dem Kurbelgehäuse (53) vorhanden ist;

einen Speicherbehälter-Teil (55), der in dem Kurbelgehäuse (53) vorhanden ist und Öl speichert;

eine Spülpumpe (91), die das Öl aus der Ölwanne (544) dem Speicherbehälter-Teil (55) zuführt; sowie

eine Ausgleichswelle (63), die zwischen wenigstens dem Teil des Speicherbehälter-Teils (55) und der Kurbelwelle (61) angeordnet und so ausgeführt ist, dass sie sich zusammen mit der Kurbelwelle (61) dreht,

dadurch gekennzeichnet, dass

in einer Versatz-Richtung (Do) jeweils orthogonal zu einer Achse (Lc) des Zylinders (511) und der Kurbel-Achse (C61) sich die Kurbel-Achse (C61) auf einer Seite (Do1) der Achse (Lc) des Zylinders (511) befindet,

wenigstens ein Teil des Speicherbehälter-Teils (55) sich auf der anderen Seite (Do2) der Achse (Lc) des Zylinders (511) in der Versatz-Richtung (Do) befindet und die Kurbelwelle (61), in der Versatz-Richtung (Do) gesehen, überlappt,

wenigstens der Teil des Speicherbehälter-Teils (55) eine erste Speicherbehälter-Kammer (553) und eine zweite Speicherbehälter-Kammer (554) umfasst, die in einer Achsenrichtung der Ausgleichswelle (63) angeordnet sind, und Öl jeweils im Inneren der ersten Speicherbehälter-Kammer (553) und der zweiten Speicherbehälter-Kammer (554) gespeichert wird,

ein Gewicht (631) der Ausgleichswelle (63) sich zwischen beiden Enden der zweiten Speicherbehälter-Kammer (554) in der Achsenrichtung der Ausgleichswelle (63) befindet,

die erste Speicherbehälter-Kammer (553) einen vorstehenden Teil (553J) enthält, der in Richtung der Ausgleichswelle (63) weiter vorsteht als die zweite Speicherbehälter-Kammer (554) in einer Normalrichtung senkrecht zu der Achsenrichtung der Ausgleichswelle (63), und

wenigstens ein Teil des vorstehenden Teils (553J), in der Achsenrichtung der Ausgleichswelle (63) gesehen, eine Drehbahn (631T) des Gewichtes (631) der Ausgleichswelle (63) überlappt.

2. Motor (5) nach Anspruch 1, der des Weiteren ein Getriebe (66) umfasst, das in dem Kurbelgehäuse (53) angeordnet ist, wobei
sich das Getriebe (66) an der einen Seite (Do1) der Achse (Lc) des Zylinders (511) in der Versatz-Richtung (Do) befindet.

3. Motor (5) nach Anspruch 1 oder 2, wobei
wenigstens der Teil des Speicherbehälter-Teils (55), in der Achsenrichtung der Ausgleichswelle (63) gesehen, sich in der über eine durch die Kurbel-Achse (C61) und eine Drehachse (C63) der Ausgleichswelle (63) hindurch verlaufende Linie (l) der Ölwanne (544) gegenüberliegenden Richtung befindet.

4. Motor (5) nach einem der Ansprüche 1 bis 3, wobei

das Kurbelgehäuse (53) eine Außenwand (531) enthält, die eine äußere Wandfläche bildet, und

wenigstens ein Teil einer Wandfläche des Speicherbehälter-Teils (55) durch die äußere Wandfläche der Außenwand (531) gebildet wird.

5. Fahrzeug (1), das umfasst:
den Motor (5) nach einem der Ansprüche 1 bis 4; sowie ein Rad (37), das von dem Motor (5) angetrieben wird.

Revendications

1. Moteur (5), comprenant :

un cylindre (511) ;

un carter (53) connecté au cylindre (511) ;

un vilebrequin (61) ;

une bielle (62) ;

un piston (512) configuré pour effectuer un mouvement en va-et-vient dans le cylindre (511) ;

le vilebrequin (61) étant connecté via la bielle (62) au piston (512), et étant configuré pour tourner autour d'un axe de manivelle (C61) conjointement avec le mouvement en va-et-vient du piston (512), au moins une partie du vilebrequin (61) étant disposée dans le carter (53) ;

un bac à huile (544) prévu dans le carter (53) ;

une partie de réservoir (55) prévue dans le carter (53) et stockant de l'huile ;

une pompe de récupération (91) qui achemine l'huile depuis le bac à huile (544) dans la partie réservoir (55) ; et

un arbre d'équilibrage (63) disposé entre au moins la partie de la partie de réservoir (55) et le vilebrequin (61) et qui est configuré pour tourner conjointement avec le vilebrequin (61),

caractérisé en ce que

dans une direction décalée (Do) orthogonale à chacun d'un axe (Lc) du cylindre (511) et de l'axe de manivelle (C61), l'axe de manivelle (C61) est situé sur un côté (Do1) de l'axe (Lc) du cylindre (511),

au moins une partie de la partie de réservoir (55) est située sur l'autre côté (Do2) de l'axe (Lc) du cylindre (511) dans la direction décalée (Do) et chevauche le vilebrequin (61) comme observé depuis le direction décalée (Do),

au moins la partie de la partie réservoir (55) comprend une première chambre de réservoir (553) et une seconde chambre de réservoir (554) agencées dans une direction axiale de l'arbre d'équilibrage (63) et de l'huile est stockée à l'intérieur de chacune des première chambre de réservoir (553) et seconde chambre de réservoir (554),

un poids (631) de l'arbre d'équilibrage (63) est situé entre les deux extrémités de la seconde chambre de réservoir (554) dans la direction axiale de l'arbre d'équilibrage (63),

la première chambre de réservoir (553) comprend une partie en saillie (553J) faisant saillie vers l'arbre d'équilibrage (63) plus loin que la seconde chambre de réservoir (554) dans une direction normale normale à la direction axiale de l'arbre d'équilibrage (63), et

au moins une partie de la partie en saillie (553J) chevauche un lieu de rotation (631T) du poids (631) de l'arbre d'équilibrage (63) comme observé depuis la direction axiale de l'arbre d'équilibrage (63).

2. Moteur (5) selon la revendication 1, comprenant en outre une transmission (66) disposée dans le carter (53), dans lequel
la transmission (66) est située sur un côté (Do1) de l'axe (Lc) du cylindre (511) dans la direction décalée (Do).

3. Moteur (5) selon la revendication 1 ou 2, dans lequel
comme observé depuis la direction axiale de l'arbre d'équilibrage (63), au moins la partie de la partie de réservoir (55) se situe dans la direction opposée du bac à huile (544) à travers une ligne (l) passant à travers l'axe de manivelle (C61) et un axe de rotation (C63) de l'arbre d'équilibrage (63).

4. Moteur (5) selon l'une quelconque des revendications 1 à 3, dans lequel le carter (53) comprend une paroi extérieure (531) formant une surface de paroi extérieure, et
au moins une partie d'une surface de paroi de la partie de réservoir (55) est configurée par la surface de paroi extérieure de la paroi extérieure (531).

5. Véhicule (1), comprenant :

le moteur (5) selon l'une quelconque des revendications 1 à 4 ; et

une roue (37) devant être entraînée par le moteur (5).

Drawing