Crankcase structure

Abstract

To provide a crank case structure which can achieve downsizing of a power unit by reducing a dimension in a front-back direction of a crank case.SOLUTION: A crank case structure adapted to a crank case (9) that houses a crankshaft (C) of a power unit (P) includes: a crank case cover (20) attached to a side surface of the crank case (C); a push rod (31) that is disposed parallel to the crankshaft (C) and reciprocates to engage or disengage a clutch (CL); and a clutch drive unit (30) that reciprocates the push rod (31). A through hole (32), through which the push rod (31) passes, is formed within a range of a sealing surface (29) which is formed in the crank case (9) to attach the crank case cover (20), and the clutch drive unit (30) is attached to the crank case cover (20).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a crankcase structure, and more particularly to a crankcase structure applied to a crankcase that houses a crankshaft. [Background technology]

[0002] BACKGROUND ART Conventionally, in a power unit in which an engine and a transmission are integrally configured, a configuration has been disclosed in which a crankcase cover that covers a generator and the like is attached to the side of a crankcase that houses a crankshaft.

[0003] Patent document 1 discloses a configuration in which a crankcase cover that covers the generator is attached to the left side of the crankcase in the vehicle width direction, and a clutch drive unit for operating the clutch to engage and disengage is attached at a position behind the crankcase cover. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-68431 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the crankcase structure of Patent Document 1, the crankcase cover and clutch drive unit are arranged in a front-to-back layout, which tends to increase the front-to-rear dimensions of the crankcase, and there is still room for improvement in order to further reduce the size of the power unit.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a crankcase structure that solves the above-mentioned problems of the prior art and that can reduce the front-to-rear dimension of the crankcase to thereby achieve a compact power unit. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a crankcase structure applied to a crankcase (9) that houses a crankshaft (C) of a power unit (P), comprising: a crankcase cover (20) attached to the side of the crankcase (C); a push rod (31) arranged parallel to the crankshaft (C) and reciprocating to connect and disconnect a clutch (CL); and a clutch drive unit (30) that reciprocates the push rod (31), wherein a through hole (32) through which the push rod (31) passes is formed within the range of a sealing surface (29) formed in the crankcase (9) for attaching the crankcase cover (20), and the clutch drive unit (30) is attached to the crankcase cover (20).

[0008] A second feature is that a drive sprocket (22) around which a drive chain (13) is wound is disposed behind the clutch drive unit (30), and the clutch drive unit (30) and the drive sprocket (22) partially overlap each other when viewed from the side of the crankcase (9).

[0009] A third feature is that the clutch drive unit (30) has a chain cover (50) that is partially attached to the rear of the crankcase cover (20) and that covers a portion of the drive chain (13), and a harness (40) is routed between the clutch drive unit (30) and the chain cover (50), and the harness (40) is housed in a groove (51) provided in the chain cover (50).

[0010] A fourth feature is that the crankcase cover (20) and the chain cover (50) partially overlap each other in a side view of the crankcase (9).

[0011] A fifth feature is that a protection plate (60) is disposed between the crankcase cover (20) and the drive sprocket (22). [Effects of the Invention]

[0012] According to a first feature, a crankcase structure applied to a crankcase (9) that houses a crankshaft (C) of a power unit (P) includes a crankcase cover (20) attached to a side of the crankcase (C), a push rod (31) arranged parallel to the crankshaft (C) and reciprocating to connect and disconnect a clutch (CL), and a clutch drive unit (30) that reciprocates the push rod (31), a through hole (32) through which the push rod (31) passes is formed within a range of a seal surface (29) formed in the crankcase (9) for attaching the crankcase cover (20), and the clutch drive unit (30) is attached to the crankcase cover (20). This makes it possible to attach the clutch drive unit to the crankcase cover, and allows the clutch drive unit to be positioned further forward than in a conventional configuration in which the clutch drive unit is directly attached to the crankcase. This reduces the longitudinal dimension of the crankcase.

[0013] According to the second feature, a drive sprocket (22) around which the drive chain (13) is wound is disposed behind the clutch drive unit (30), and the clutch drive unit (30) and the drive sprocket (22) partially overlap in a side view of the crankcase (9), making it possible to reduce the front-to-rear dimension of the crankcase.

[0014] According to the third feature, a chain cover (50) is provided, a portion of which is attached to the rear of the crankcase cover (20) and which covers a portion of the drive chain (13), and a harness (40) is routed between the clutch drive unit (30) and the chain cover (50), and the harness (40) is housed in a groove (51) provided in the chain cover (50). This makes it possible to protect the harness from external forces and the like, and also makes it difficult to see the harness from the outside, thereby improving the appearance.

[0015] According to the fourth feature, the crankcase cover (20) and the chain cover (50) partially overlap each other in a side view of the crankcase (9), so that the front-to-rear dimension of the crankcase can be further reduced.

[0016] According to the fifth feature, a protective plate (60) is disposed between the crankcase cover (20) and the drive sprocket (22), so that the crankcase and the crankcase cover can be protected from flying stones and the like that may be kicked up by the drive chain. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a left side view of a motorcycle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged left side view of FIG. [Figure 3] FIG. 2 is a partially enlarged left side view of the state in which the clutch drive unit is removed. [Figure 4] FIG. 2 is a left side view of the crankcase with the crankcase cover removed. [Figure 5] FIG. 2 is a perspective view showing the mounting structure of the chain cover. [Figure 6] FIG. 2 is a left side view of the crankcase 9 with the chain cover removed. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 2. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 2. [Figure 9] FIG. 10 is a partially enlarged left side view of a power unit according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] A preferred embodiment of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a left side view of a motorcycle 1 according to this embodiment. The motorcycle 1 is an off-road straddle-type vehicle in which power from a power unit P, which is an integrated combination of an engine and a transmission, is transmitted to a rear wheel WR via a drive chain 13.

[0019] A head pipe F1, which rotatably supports a steering stem shaft (not shown), is attached to the front end of a pair of left and right main frames F2 that make up the body frame F. A top bridge 4 is fixed to the upper end of the steering stem shaft, and a bottom bridge 5 is fixed to the lower end of the steering stem shaft. A front wheel WF is rotatably supported at the lower ends of a pair of left and right front forks 7 supported by the top bridge 4 and bottom bridge 5. A steering handlebar 3 is attached to the top of the top bridge 4, and a front fender 6 is attached to the front forks 7, positioned above the front wheel WF.

[0020] A pair of left and right pivot frames F3 are connected to the lower rear end of the main frame F2. The pivot frames F3 support a pivot 10 that pivotally supports a swing arm 12 so that it can swing up and down. A rear wheel WR is pivotally supported at the rear end of the swing arm 12 so that it can rotate freely. The swing arm 12 is suspended from the main frame F2 by a rear cushion 11 via a link mechanism.

[0021] A power unit P is suspended below the main frame F2 and in front of the pivot 10. A cylinder block 8 that slidably houses pistons and a cylinder head 18 that houses a valve mechanism are attached to the top of a crankcase 9 that houses the crankshaft of the power unit P. Combustion gas from the power unit P is discharged rearward from a muffler 14 at the rear of the vehicle body.

[0022] A fuel tank 2 is disposed on top of the main frame F2, and a seat 17 is disposed behind the fuel tank 2. A pair of left and right side covers 15 are disposed below the seat 17, and a rear fender 19 is disposed behind the side covers 15. The left side cover 15 in the vehicle width direction has an opening 16 for introducing outside air into an air cleaner box (not shown).

[0023] Fig. 2 is a partially enlarged left side view of Fig. 1. Fig. 3 is a partially enlarged left side view of Fig. 1 with the clutch drive unit 30 removed. A crankcase cover 20 (shown in gray) that covers a generator and other components disposed coaxially with the crankshaft C is attached to the left side surface in the vehicle width direction of the crankcase 9, which is made of a metal such as aluminum. The crankcase cover 20, which is made of a metal such as aluminum or a synthetic resin, is attached to the crankcase 9 with a plurality of bolts 75.

[0024] A clutch drive unit 30 (shown by dotted hatching in the figure) for driving a clutch that connects and disconnects power transmitted from the crankshaft C to the transmission is attached to the crankcase cover 20. The hydraulic clutch drive unit 30 is attached to a joint surface 24 formed on the left side surface of the crankcase cover 20 with three bolts 76.

[0025] The clutch drive unit 30 drives the clutch by reciprocating a push rod 31 in the vehicle width direction in response to operation of a clutch lever (not shown) attached to the steering handle 3. A clutch hose 41 that supplies hydraulic pressure generated in response to operation of the clutch lever is connected to the upper part of the clutch drive unit 30. A starter motor 26 for starting the power unit P is attached to the upper end of the crankcase 9.

[0026] A chain cover 50 is disposed behind the crankcase cover 20, covering a portion of the drive sprocket 22 around which the drive chain 13 is wound. An upper bolt 90 that secures the upper front end of the chain cover 50 is threaded into the crankcase cover 20, and a lower bolt 91 that secures the lower front end of the chain cover 50 is threaded into the crankcase 9.

[0027] A gear position sensor 25 that detects the gear position of the transmission is disposed below the chain cover 50. A harness 40 that outputs a sensor signal from the gear position sensor 25 is routed upward between the crankcase cover 20 and the chain cover 50. A shift spindle 23 that supports a shift pedal 21 operated by the driver with the left foot is disposed behind the gear position sensor 25. The shift spindle 23 rotates in response to operation of the shift pedal 21, thereby changing the gear position of the transmission.

[0028] 4 is a left side view of the crankcase 9 with the crankcase cover 20 removed. A seal surface 29 for attaching the crankcase cover 20 is formed on the left side of the crankcase 9. Inside the seal surface 29, there are arranged a generator G, a drive gear 27 fixed to the output shaft of the starter motor 26, and a large-diameter driven gear 28 that engages with the drive gear 27.

[0029] This embodiment is characterized in that a through-hole 32 through which a push rod 31 passes is formed within the range of the seal surface 29 for attaching the crankcase cover 20, and the clutch drive unit 30 is attached to the crankcase cover 20. This makes it possible to position the clutch drive unit 30 closer to the front than in a conventional configuration in which the clutch drive unit 30 is directly attached to the crankcase 9. As a result, the front-to-rear dimension of the crankcase 9 can be reduced, and the power unit P can be made more compact.

[0030] Furthermore, by attaching a portion of the chain cover 50 to the rear end portion of the crankcase cover 20, the crankcase cover 20 and the chain cover 50 partially overlap in a side view of the crankcase 9, which makes it possible to further reduce the front-to-rear dimension of the crankcase 9.

[0031] Figure 5 is a perspective view showing the mounting structure of the chain cover 50. Figure 6 is a left side view of the crankcase 9 with the chain cover 50 removed. The drive sprocket 22 is fixed to the countershaft 70, which serves as an output shaft and protrudes from the left side of the crankcase 9. As described above, the through-hole 32 through which the push rod 31 passes is disposed within the range of the seal surface 29 for mounting the crankcase cover 20.

[0032] The upper front end of the chain cover 50 is fastened to the crankcase cover 20 together with a protective plate 60 located in front of the drive sprocket 22 by bolts 90. Meanwhile, the lower front end of the chain cover 50 is fastened to the crankcase 9 together with the protective plate 60 by bolts 91. The protective plate 60 is made of a vertically long plate-like member that curves to cover the front of the drive sprocket 22.

[0033] The harness 40 is routed between the clutch drive unit 30 and the chain cover 50. A groove 51 for accommodating the harness 40 is formed in the front of the chain cover 50. By routing the harness 40 in this groove 51, the harness 40 can be protected from external forces and the like, and the harness 40 can be made less visible from the outside, improving the appearance.

[0034] Figure 7 is a cross-sectional view taken along line VII-VII in Figure 2. Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 2. The transmission of the power unit P includes a drive gear train M1 supported by a main shaft 65 that rotates using power from the crankshaft C, and a driven gear train M2 supported by a countershaft 70. A push rod 31 that connects and disconnects the clutch CL, which is disposed on the right side of the crankcase 9 in the vehicle width direction, is disposed so as to pass through the main shaft 65.

[0035] The clutch drive unit 30 according to this embodiment has a configuration in which a hydraulic piston 34 for pressing a push rod 31 is housed inside a casing 33 made of metal such as aluminum. A rear end L1 of the casing 33 is located rearward of a front end L2 of the drive sprocket 22, so that the clutch drive unit 30 and the drive sprocket 22 partially overlap in a side view of the crankcase 9. This makes it possible to reduce the longitudinal dimension of the crankcase 9.

[0036] The protective plate 60, which is located behind the crankcase cover 20 and in front of the drive sprocket 22, has the function of protecting the crankcase 9 and the crankcase cover 20 from flying stones and the like that may be picked up by the drive chain 13.

[0037] FIG. 9 is a partially enlarged left side view of a power unit P according to a modified example of the present invention. The same reference numerals as those used above indicate the same or equivalent parts. A mechanical clutch drive unit 80 can be attached to the side of the crankcase 9 in place of the hydraulic clutch drive unit 30 described above. The clutch drive unit 80 is configured so that pulling a clutch cable (not shown) causes a swing arm 81 to swing, thereby rotating a drive shaft 82 and pressing against a push rod 31. In the crankcase structure according to the present invention, the clutch drive unit is attached to the crankcase cover, making it easy to replace the clutch drive unit.

[0038] The shape of the motorcycle, the configuration of the power unit, the structure of the clutch, the shape and structure of the crankcase and crankcase cover, the shape and structure of the clutch drive unit, the shape and arrangement of the push rod, the shape of the sealing surface, the shape of the protective plate, etc. are not limited to the above-described embodiment and can be modified in various ways. For example, the crankcase cover and the clutch drive unit may be attached to the right side surface of the crankcase in the vehicle width direction. The crankcase structure according to the present invention can be applied to various vehicles having a crankcase. [Explanation of symbols]

[0039] 1...motorcycle, 9...crankcase, 13...drive chain, 20...crankcase cover, 22...drive sprocket, 29...seal surface, 30...clutch drive unit, 31...push rod, 32...through hole, 40...harness, 50...chain cover, 51...groove, 60...protective plate, P...power unit, C...crankshaft, CL...clutch

Claims

1. A crankcase structure applied to a crankcase (9) that houses a crankshaft (C) of a power unit (P), a crankcase cover (20) attached to a side surface of the crankcase (C); a push rod (31) arranged parallel to the crankshaft (C) and reciprocating to connect and disconnect the clutch (CL); a clutch drive unit (30) for reciprocating the push rod (31); A through hole (32) through which the push rod (31) passes is formed in a sealing surface (29) formed in the crankcase (9) for attaching the crankcase cover (20), A crankcase structure characterized in that the clutch drive unit (30) is attached to the crankcase cover (20).

2. A drive sprocket (22) around which a drive chain (13) is wound is disposed behind the clutch drive unit (30), 2. The crankcase structure according to claim 1, wherein the clutch drive unit and the drive sprocket partially overlap each other in a side view of the crankcase.

3. a chain cover (50) that is partially attached to the rear of the crankcase cover (20) and that covers a portion of the drive chain (13); A harness (40) is routed between the clutch drive unit (30) and the chain cover (50), 3. The crankcase structure according to claim 2, wherein the harness (40) is housed in a groove (51) formed in the chain cover (50).

4. 4. The crankcase structure according to claim 3, wherein the crankcase cover and the chain cover partially overlap each other in a side view of the crankcase.

5. 5. The crankcase structure according to claim 4, wherein a protective plate (60) is disposed between the crankcase cover (20) and the drive sprocket (22).

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