JP4338110B2 - Small vehicle engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine mounted on a small vehicle such as a saddle-ride type vehicle (four-wheel buggy vehicle or the like) that requires a reverse switching function, and particularly, in a crankcase in such a small vehicle engine. The present invention relates to an arrangement structure of each axis including a reverse axis.
[0002]
[Prior art]
As a motorcycle engine, in a crankcase that also serves as an oil pan and a mission case, the balancer shaft, which is the rotation shaft of the balancer for canceling the lateral vibration of the crankshaft, is parallel to the crankshaft. A transmission-integrated compact engine that has been installed on each transmission shaft (main shaft and counter shaft) to shift and output the transmitted engine torque in several stages has been generally used. Has been.
[0003]
[Problems to be solved by the invention]
By the way, in a small vehicle such as a four-wheel (or three-wheel) buggy having a saddle-type seat such as a motorcycle seat, a compact engine for a motorcycle as described above is to be used. Since motorcycles do not reverse the vehicle body, the engine transmission is not provided with a reverse switching mechanism, whereas vehicles such as four-wheel buggy vehicles sometimes reverse the vehicle body. It is necessary to add a reverse switching mechanism to this transmission.
[0004]
However, if a reverse shaft that rotatably supports the reverse gear is added as a reverse switching mechanism to the main shaft and the counter shaft of the transmission in the engine crankcase, for example, Japanese Utility Model Laid-Open No. 3-32110 As can be seen from the official gazette, the entire crankcase becomes longer in the longitudinal direction of the vehicle body, and the compactness of the entire engine is impaired.
[0005]
An object of the present invention is to solve the above-described problems. Specifically, in a small vehicle engine that requires a reverse switching function, each of the shafts including the reverse switching reverse shaft is connected to the crankcase. It is an object of the present invention to make the entire engine compact by disposing the engine in a compact state.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a rotating shaft of a balancer in a crankcase that is located at the lower rear portion of an engine and also serves as a transmission case and is parallel to a crankshaft having a balance weight. In a small vehicle engine provided with a balancer shaft, a transmission main shaft and a counter shaft, and a reverse shaft that rotatably supports a reverse gear, the transmission main shaft and the counter shaft The reverse shaft is disposed above, the balancer shaft is disposed between the reverse shaft and the crankshaft , and a plurality of shift gears and dog clutches provided on the main shaft and the counter shaft are used to at one end of the crankcase deviating in the axial direction by placing the reverse switching mechanism including a reverse gear, the balancer And the reverse shaft are arranged close to each other so that the balancer and the reverse gear overlap with each other when viewed from the axial direction, and the balancer shaft and the crankshaft are balanced with the balancer when viewed from the axial direction. The weights are arranged close to each other so that the rotation trajectories overlap.
[0007]
According to the structure as described above, a reverse shaft that supports the reverse gear is added to the crankcase without the length of the entire crankcase in the longitudinal direction of the vehicle body as much as that of a normal motorcycle engine. The reverse engine can be provided with a reverse switching function, and the entire engine can be maintained in a compact state.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a small vehicle engine of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a vehicle equipped with an engine, FIG. 2 shows an arrangement state of each shaft in the crankcase of the engine as seen from the side, and FIG. FIG. 2 shows a developed cross section passing through each shaft installed in the crankcase in the order of a balancer shaft, a reverse shaft, a main shaft, and a counter shaft.
[0009]
The small vehicle 1 on which the engine of this embodiment is mounted is a four-wheel buggy vehicle for running on rough terrain, which is called a saddle-type vehicle, and as shown in FIG. The engine 3 is mounted in the vicinity, and the steering front wheel 5 that is steered by the operation of the steering handle 4 and the driving rear wheel 6 that is driven by the rotation of the engine 3 are provided in pairs. Balloon tires (wide ultra-low pressure tires) are used for the front wheel 5 and rear wheel 6 tires.
[0010]
The axle 7 of the pair of left and right rear wheels 6 is rotatably held at the rear end of a rear arm 8 that can swing up and down, and the front end of the rear arm 8 is pivotally supported on the vehicle body frame by a pivot shaft 9. A cushion unit (coil spring and shock absorber) 10 is interposed between the vicinity of the rear end and the vehicle body frame. The drive sprocket 11 is fixed to the output shaft of the engine 3 and the driven is fixed to the axle 7 of the rear wheel 6. A chain 13 for power transmission is wound around the sprocket 12.
[0011]
The engine 3 mounted on such a small vehicle 1 is a four-cycle single-cylinder engine. Conventionally, the engine 3 is generally used in a motorcycle except for a reverse switching mechanism such as a reverse gear 25 and a reverse shaft 26 described later. The engine has almost the same structure as the engine used in general, and the outline thereof will be described below.
[0012]
As shown in FIG. 2 or 3, in the engine 3 in which the head cover 15, the cylinder head 16, the cylinder block 17 and the crankcase 18 are integrally connected, the crankcase 18 also serves as an oil pan and a mission case. The crankcase 18 has a left / right split structure in which left and right members 18a, 18b are coupled.
[0013]
In such a left-right split crankcase 18, the balancer shaft 22 that is the rotation shaft of the balancer 21, the main shaft 23 of the transmission, and the counter so as to be in an axial direction parallel to the crankshaft 19 extending in the vehicle body width direction. A shaft 24 (which serves as an output shaft of the engine) is rotatably installed via a bearing member, and a reverse shaft 26 which rotatably supports a reverse gear 25 for reverse switching is fixedly installed. ing.
[0014]
The balancer 21 is generated by the centrifugal force of the balance weight 20 provided on the crankshaft 19 itself in order to cancel the reciprocating inertia force of the piston in the case of a single cylinder engine or a multi-cylinder engine having the same crank arm phase. Therefore, this engine 3 is provided to cancel such lateral vibration of the crankshaft 19. In this engine 3, the crankcase 18 is made compact in the longitudinal direction of the vehicle body. These are installed at one location obliquely above the rear of the crankshaft 19.
[0015]
With respect to the transmission, except for the reverse gear 25 and the reverse switching mechanism portion of the main shaft 23 and the counter shaft 24 that are meshed with the reverse gear 25 and the counter shaft 24, the conventional continuously meshed five-speed transmission that has been generally used in motorcycles. The rotation of the main shaft 23 can be performed at any speed from 1st to 5th by engaging a plurality of shift gears and dog clutches provided on the main shaft 23 and the counter shaft 24 in any combination. The gear ratio is transmitted to the counter shaft 24.
[0016]
Note that a power transmission mechanism from the crankshaft 19 to the main shaft 23 of the transmission is not shown, but the rotation of the crankshaft is transmitted to the main shaft of the transmission via a reduction gear and a multi-plate clutch. Therefore, the motorcycle has a general structure, and a multi-plate clutch (not shown) is connected to one end side 23a of the main shaft 23 protruding from the crankcase 18.
[0017]
Also, although not shown in the figure, the operation mechanism of the transmission is spline-engaged on each shaft of the transmission by rotating the shift drum and sliding the fork by operating the shift pedal. One of the dog clutch-equipped gears is slid and has a general structure in a conventional motorcycle.
[0018]
In addition to the conventional general structure of a motorcycle engine as described above, in the engine 3 of the present embodiment, in the crankcase 18, the reverse travel is performed above the main shaft 23 and the counter shaft 24 of the transmission. A reverse shaft 26 for rotatably supporting a reverse gear 25 for switching is provided, and the main shaft 23 and the counter shaft 24 are respectively rotatable with gears 27 and 28 that are always meshed with the reverse gear 25. I support it.
[0019]
Then, the balancer as viewed from the side of the engine 3 (the axial direction of the balancer shaft 22 and the reverse shaft 26) of the reverse shaft 26 that rotatably supports the reverse gear 25 and the balancer shaft 22 that is the rotation shaft of the balancer 21. The balancer shaft 22 that is the rotation shaft of the balancer 21 and the crankshaft 19 having the balance weight 20 are arranged on the side of the engine 3. The balancer 21 and the balance weight 20 are arranged close to each other so that the rotation trajectories of the balancer 21 and the balance weight 20 overlap each other when viewed from the axial direction of the balancer shaft 22 and the crankshaft 19 .
[0020]
In the present embodiment, the reverse gear 25 is disposed on one end side of the reverse shaft 26 (on the side opposite to the input side 23a of the main shaft 23), and the balancer shaft 22 has a needle end on one end side close to the reverse gear 25. The bearing 30 is pivotally supported on the crankcase 18 (18b), and the other end is pivotally supported by the ball bearing 31 on the crankcase 18 (18a).
[0021]
In the present embodiment, the hollow shaft core portion 26a of the reverse shaft 26 is oil for injecting lubricating oil to the transmission gears respectively provided on the main shaft 23 and the counter shaft 24 of the transmission. It is a passage.
[0022]
According to the engine 3 of the present embodiment in which the reverse shaft 26 and the balancer shaft 22 are arranged as described above, the reverse shaft 26 is connected to the balancer shaft 22 above the main shaft 23 and the counter shaft 24 of the transmission. By arranging the balancer shaft 22 close to the crankshaft 19 above the reverse shaft 26 and the crankshaft 19, the crankcase 18 of the engine 3 can be placed in the front-rear direction of the vehicle body. The balancer 21 and the balancer shaft 22 can be installed without making it so long in the direction, and the reverse gear 25 and the reverse shaft 26 can be additionally installed, which is substantially the same as a conventional motorcycle engine. Thus, it is possible to provide the engine 3 with a reverse switching function.
[0023]
Further, in the present embodiment, one end side of the balancer shaft 22 close to the reverse gear 25 is pivotally supported on the crankcase 18 by the small-diameter needle bearing 30 so that the crankcase 18 does not have to be elongated in the longitudinal direction of the vehicle body. The crankcase 18 can be made compact in the vehicle body width direction without causing the bearing portion of the balancer shaft 22 and the reverse gear 25 to interfere with each other.
[0024]
In the present embodiment, the hollow shaft core portion 26a of the reverse shaft 26 disposed above the main shaft 23 and the counter shaft 24 of the transmission is used as an oil passage for injecting lubricating oil, so that another member is provided. The lubricating oil can be effectively injected from above to each transmission gear of the transmission.
[0025]
As mentioned above, although one embodiment of the engine for small vehicles of the present invention was described, the present invention is not limited to the above embodiment, for example, a 4-cycle single cylinder as shown in the above embodiment It can be applied not only to the engine but also to other engines, and has a specific structure such as a power transmission mechanism from the crankshaft to the transmission, a transmission gear configuration of the transmission, and an operation mechanism of the transmission. In addition, the present invention is not limited to the specific structure as shown in the above embodiment, and the use of the engine can also be used in vehicles other than the four-wheel buggy car as shown in the above embodiment. Needless to say, these can be changed as appropriate.
[0026]
【The invention's effect】
According to the small vehicle engine of the present invention as described above, the shaft including the reverse shaft for reverse switching can be arranged in a compact state in the crankcase, so that the crankcase of the engine can be moved in the vehicle longitudinal direction. The reverse gear and the reverse shaft can be additionally installed without making it so long, and while maintaining the same compactness as a conventional motorcycle engine, the reverse switching function is given to the engine. be able to.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view showing an outline of a straddle-type vehicle (four-wheel buggy) that is an example of a small vehicle equipped with an engine of the present invention.
FIG. 2 is an explanatory side view showing an arrangement state of each shaft in a crankcase according to an embodiment of a small vehicle engine of the present invention.
FIG. 3 is a developed cross-sectional view passing through each axis in the crankcase shown in FIG. 2 in the order of a balancer shaft, a reverse shaft, a main shaft, and a counter shaft.
[Explanation of symbols]
1 Small vehicle (four-wheel buggy)
3 Engine 18 Crankcase 19 Crankshaft 21 Balancer 22 Balancer shaft 23 (Transmission) Main shaft 24 (Transmission) Counter shaft 25 Reverse gear 26 Reverse shaft 26a Oil passage 30 Needle bearing

Claims (3)

A balancer shaft, which is the rotation shaft of the balancer, a main shaft and a counter shaft of the transmission, and a reverse gear, in parallel with the crankshaft having a balance weight, in a crankcase that is located at the lower rear part of the engine and also serves as a transmission case In a small vehicle engine provided with a reverse shaft that rotatably supports the reverse shaft, the reverse shaft is disposed above the main shaft and the counter shaft of the transmission. The balancer shaft is disposed between the crankshafts, and a reverse gear is provided at one end in the crankcase that is disengaged in the axial direction from the plurality of shift gears and dog clutches provided on the main shaft and the countershaft. reverse switching mechanism comprising been placement, and the balancer shaft and the reverse shaft, or their axial The balancer and the reverse gear are arranged close to each other so that the balancer and the reverse gear overlap, and the balancer shaft and the crankshaft are overlapped with each other so that the balancer and the balance weight rotation locus overlap when viewed in the axial direction. The engine for small vehicles characterized by being arrange | positioned in proximity to. 2. The small vehicle according to claim 1, wherein a reverse gear is disposed at one end of the reverse shaft, and one end of the balancer shaft close to the reverse gear is supported by a crankcase via a needle bearing. engine. 3. The small vehicle engine according to claim 1, wherein an oil passage for injecting lubricating oil to each transmission gear provided on each shaft of the transmission is formed in a reverse shaft. .

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