JP2005090373A - Intake device for four cycle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake device for a four cycle engine capable of reducing ventilation resistance in a suction passage and improving engine output. <P>SOLUTION: This intake device for the four cycle engine is constituted in such a way that a suction pipe 19 in which two individual passage parts 18a, 18b are formed is provided and fixed to a cylinder head 9 and two individual passage parts 18a, 18b are communicated with respective suction ports 14a, 14b. Two carburetors 20a, 20b are arranged in the suction pipe 19, and air-fuel mixture is supplied into each of two sets of suction passages 21, 22 constituted by the suction ports 14a, 14b and the individual passage parts 18a, 18b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an intake device for a four-cycle engine in which an air-fuel mixture generated using a carburetor is supplied to a combustion chamber.

  Roughly terrain vehicles or all-terrain vehicles (ATVs), also known as buggy vehicles, are off-road vehicles for four-wheeled single riders, and for leisure purposes such as hunting and trail touring. It is also used as an agricultural utility vehicle. In such all-terrain vehicles, the throttle valve opening is changed by the driver's accelerator operation to adjust the amount of air, and the amount of fuel necessary to realize the set air-fuel ratio is controlled to achieve the desired engine. I am getting output.

  Such all-terrain vehicles include a vehicle equipped with a carburetor as a device that generates an air-fuel mixture using air and fuel. This carburetor has a venturi upstream of the throttle valve, continuously sucks fuel in the float chamber by the negative pressure of the venturi generated by the air flow, mixes the atomized fuel and the air sucked from the air cleaner, and mixes the mixture Is generated.

In an engine having a plurality of cylinders using a carburetor, usually, an air-fuel mixture generated by the carburetor is fed into a cylinder as a combustion chamber while being uniformly mixed through an intake manifold. On the other hand, as in the technique disclosed in Patent Document 1, for example, there are carburetors corresponding to the respective cylinders, and the air-fuel mixture generated by the separate carburetors is supplied into the cylinders. Like to do.
JP 2002-235551 A

  In recent four-cycle engines, in order to increase engine output, a type in which a plurality of intake ports and exhaust ports are formed in a cylinder head has become the mainstream. For example, in order to increase the output of a single-cylinder four-cycle engine, an engine has been developed in which the engine displacement is increased and two intake ports and two exhaust ports are provided. Conventionally, when air-fuel mixture is supplied into the cylinder from two intake ports, the air-fuel mixture generated by the carburetor is supplied through a common passage immediately before the outlet of the intake port and both immediately before the outlet. It is made to branch to the spout. The gas mixture is guided by the common passage in the same kind of gas generated in the carburetor in order to achieve uniform stirring of the air-fuel mixture in the common passage. It was the same.

  By the way, in order to increase the intake charge rate in the fuel chamber, it is required to reduce the ventilation resistance in the intake passage from the carburetor to the injection port as much as possible. Therefore, the inner surface of the intake pipe such as the intake manifold is made as smooth as possible, and the intake pipe is formed so as to reduce unnecessary bending, but it is vaporized to reduce the airflow resistance of the intake passage to the jet outlet. As a result of various researches on ventilators, if the air-fuel mixture is supplied to the intake ports including the carburetor via mutually independent and independent intake passages, the ventilation resistance of each intake passage decreases. As a result, it has been found that an improvement in the intake charge rate into the combustion chamber can be achieved. The reason for this is considered to be that when a common intake passage is provided, airflow is disturbed at a branch point provided immediately before the ejection port, and the ventilation resistance in the common intake passage is increased.

  An object of the present invention is to provide an intake device for a four-cycle engine that can reduce ventilation resistance in the intake passage and improve engine output.

  An intake device for a four-cycle engine according to the present invention is an intake device for a four-cycle engine that performs intake and exhaust of an air-fuel mixture in a combustion chamber by an intake valve and an exhaust valve that are driven to open and close by a valve cam, respectively. Two independent intake ports formed in the cylinder head independently, and in which the intake valve is reciprocably mounted, and two individual ports fixed to the cylinder head and communicating with the intake ports, respectively. Two vaporizers that are provided in each of the intake pipe formed with the passage portion and each of the individual passage portions and supply the air-fuel mixture to each of two sets of intake passages constituted by the intake port and the individual passage portions It is characterized by having a vessel.

  In the present invention, two sets of intake passages are formed by two intake ports and individual passage portions that are independently formed without merging with each other, thereby reducing the ventilation resistance of the intake passage. The engine output can be improved by increasing the intake charge rate in the combustion chamber.

  By disposing a carburetor in each of the two sets of intake passages, a larger amount of air-fuel mixture can be supplied with high accuracy. Further, the amount of air-fuel mixture supplied from each intake port into the combustion chamber can be individually controlled.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a vehicle in which a power transmission device is incorporated. This vehicle is an ATV, which is also called a buggy, that is, a rough terrain vehicle. As shown in FIG. 1, the vehicle body 1 is provided with front wheels 2 a and 2 b and rear wheels 3 a and 3 b, and a saddle-ride type seat 4 is provided at the center of the vehicle body 1. The occupant gets into the vehicle across the seat 4 and operates by operating the handle 5.

  2 is a schematic view showing a vehicle power transmission device according to an embodiment of the present invention mounted on the vehicle of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. 4 is a cross-sectional view of the cylinder head 9 as viewed from above. As shown in FIG. 2, a crankshaft 7 is rotatably accommodated via a bearing in a crankcase 6 formed by two case halves 6a and 6b. A cylinder 8 is attached to an opening formed in the upper part of the case 6, and a cylinder head 9 is mounted on the cylinder 8. A piston 10 is incorporated in the cylinder bore of the cylinder 8 so as to be able to reciprocate. A connecting rod 12 is provided between the piston 10 and a hollow crankpin 11 fixed to the crankshaft 7 at a position eccentric from the center of rotation. The crankshaft 7 is driven to rotate by the piston 10. The engine formed by the cylinder 8 and the cylinder head 9 is a single-cylinder water-cooled four-cycle engine.

  As shown in FIGS. 3 and 4, the cylinder head 9 has two intake ports 14 a and 14 b and two exhaust ports 15 a and 15 b that are open to the combustion chamber 13 and formed independently. An intake valve 16 for opening and closing the intake ports 14a and 14b is reciprocally attached to the cylinder head 9, and an exhaust valve 17 for opening and closing the respective exhaust ports 15a and 15b is reciprocally attached to the cylinder head 9. Has been.

  As shown in the figure, an intake pipe 19 having two individual passage portions 18a and 18b is fixed to the cylinder head 9, and two individual passage portions 18a and 18b are provided in the intake ports 14a and 14b, respectively. Are communicating. The intake pipe 19 is provided with two carburetors 20a and 20b (so-called twin carburetors) that generate a mixture of air and fuel. The intake ports 14a and 14b and the individual passage portions 18a and 18b The air-fuel mixture is supplied to each of the two sets of intake passages 21 and 22 that are configured. The generated air-fuel mixture is taken into the combustion chamber 13 from the intake ports 14a and 14b when the intake valve 16 is in the open state.

  In this way, the air-fuel mixture flowing in the intake passages 21 and 22 does not merge until they pass through the intake ports 14a and 14b, respectively, so that they do not interfere with each other and air flow disturbance is less likely to occur. ing. In addition, each of the intake ports 14a, 14b and the individual passage portions 18a, 18b can be independently set in shape and size, so that, for example, useless bending is not made so as to reduce ventilation resistance. Can be formed. In addition, by disposing the carburetors 20a and 20b in the two sets of intake passages 21 and 22, a larger amount of the air-fuel mixture can be supplied with high accuracy. Further, the amount of the air-fuel mixture supplied from the intake ports 14a and 14b into the combustion chamber 13 can be individually controlled. In general, the carburetor has a simple structure and low manufacturing cost. Therefore, a twin carburetor with one additional carburetor has a significant increase in manufacturing cost and difficulty in securing installation space. Never become.

  Two camshafts 23 and 24 for the intake valve and the exhaust valve are rotatably mounted on the cylinder head 9, and a valve cam 25 is fixed to the camshaft 23, and the camshaft 24 has a motion. A valve cam 26 is fixed, and the valve cams 25 and 26 are in contact with the base end portions of the camshafts 23 and 24, respectively. Thus, the illustrated valve mechanism is a direct-acting DOHC type. However, the valve mechanism may be a DOHC type or SOHC type in which the intake valve 16 and the exhaust valve 17 are driven to open and close by a valve cam via a rocker arm. Each of the camshafts 23 and 24 is provided with two intake valves 16 and two exhaust valves 17 corresponding to the two intake ports 14a and 14b and the two exhaust ports 15a and 15b. Two valve cams 25 and 26 are fixed to the camshafts 23 and 24, respectively.

  As shown in FIG. 2, a sprocket 27 is fixed to the crankshaft 7, and a timing chain (not shown) is hung between the sprocket 27 and a sprocket (not shown) fixed to each camshaft 23, 24. The camshafts 23 and 24 are driven to rotate in synchronization with the rotation of the crankshaft 7.

  As shown in FIG. 2, a balancer shaft 31 is rotatably mounted on the crankcase 6, and a gear 32 b that meshes with a gear 32 a fixed to the crankshaft 7 is fixed to the balancer shaft 31. 7 is rotated in synchronism with this. The balancer shaft 31 is provided with a balance weight 33 as shown in FIG. 3 for smooth rotation of the crankshaft 7. Further, a pump impeller 34 is attached to the balancer shaft 31 as shown in FIG. 2, and the pump impeller 34 is formed in a pump housing formed by a part of the crankcase 6 and a pump cover 35 attached thereto. The engine coolant is supplied from a water pump to a water jacket 8 a formed in the cylinder 8.

  As shown in FIG. 2, a starter gear 36 is rotatably mounted on the crankshaft 7, and a rotor 37 a having a permanent magnet is fixed to the crankshaft 7 adjacent to the starter gear 36. A power generator cover 6c fixed to the crankcase 6 is attached with a stator 37b having a coil, and the power generator 37 is constituted by the rotor 37a and the stator 37b. A one-way clutch 38 is incorporated between the rotor 37a and the starter gear 36, and the starter gear 36 is connected to a gear of a starter motor (not shown). When the engine is started, the rotation of the starter gear 36 that is rotationally driven by the starter motor is transmitted to the crankshaft 7 via the one-way clutch 38. On the other hand, under the state where the engine is driven, the rotation of the rotor 37a driven by the crankshaft 7 is prevented from being transmitted to the starter gear 36 by the one-way clutch 38.

  As shown in FIG. 2, a hollow main shaft 41 as a transmission input shaft and a counter shaft 42 as a transmission output shaft are rotatably mounted on the crankcase 6 and are parallel to each other. . The drive gear 43a fixed to the crankshaft 7 meshes with a driven gear 43b that is rotatably attached to the main shaft 41, and the driven gear 43b has a vibration damping damper 44 incorporated therein. To the clutch drum 45. On the other hand, a clutch hub 46 is fixed to the main shaft 41. Between the clutch hub 46 and the clutch drum 45, a plurality of clutch disks 45 a mounted inside the clutch drum 45 and on the outside of the clutch hub 46. A plurality of attached clutch disks 46a are incorporated. Thus, the input clutch 47 is constituted by the respective clutch disks 45a and 46a, and when the clutch disks 45a and 46a are engaged, the rotation of the crankshaft 7 is transmitted to the main shaft 41 via the input clutch 47 and engaged. Is released to release the power transmission to the main shaft 41 of the crankshaft 7. A cover 6 d that covers the input clutch 47 is attached to the case 6.

  In order to switch the input clutch 47 between the engaged state and the released state, the input clutch 47 is provided with an operating plate 48, and the operating plate 48 is a spring in a direction in which the clutch disks 45a, 46a are brought into close contact with a spring member (not shown). Power is applied. A push rod 49 is incorporated in the hollow hole of the main shaft 41 so as to be slidable in the axial direction, and the push rod 49 is attached to the operation plate 48 via a bearing. As shown in FIG. 1, the push rod 49 is connected to a clutch lever 5a provided on the handle 5 via a wire. When the push rod 49 moves to the left in FIG. 2 by operating the clutch lever 5a, Transmission of power to the main shaft 41 of the crankshaft 7 is interrupted, and when the clutch lever 5a is released, the input clutch 47 is engaged by the spring force.

  As shown in FIG. 2, a drive gear 51a for the first speed is integrally provided on the main shaft 41, and drive gears 52a and 53a for the second speed and the third speed are provided in the dog clutch D1. The dog clutch D1 is engaged with a spline formed on the main shaft 41, rotates integrally with the main shaft 41, and is movable in the axial direction. Further, two gears 54a and 55a for the fourth speed and the fifth speed are rotatably mounted on the main shaft 41 so as to be positioned on both sides of the dog clutch D1. On the other hand, the countershaft 42 is a first-speed driven gear 51b that always meshes with the drive gear 51a to form a transmission gear train, and a second gear that always meshes with the drive gears 52a and 53a to form a transmission gear train. High-speed and third-speed driven gears 52b and 53b are rotatably mounted, respectively. The countershaft 42 further includes a dog clutch D2 provided with a driven gear 54b for the fourth speed that is always meshed with the drive gear 54a to form a transmission gear train, and a gear train that is always meshed with the drive gear 55a. A dog clutch D3 provided with a fifth-speed driven gear 55b to be formed is provided. Each of the dog clutches D2 and D3 constitutes a switching sleeve, and rotates integrally with the counter shaft 42 and is movable in the axial direction.

  As shown in FIG. 5, protrusions 50 are provided at predetermined intervals in the circumferential direction on both end faces of each of the dog clutches D1 to D3. The protrusions 50 are moved in the axial direction to correspond to the protrusions 50. When the gears are engaged with the recesses formed in the gears, the engaged gears are in a state of transmitting power through the dog clutches D1 to D3. For example, when the dog clutch D3 is meshed with the first speed driven gear 51b, the driven gear 51b is rotated integrally with the counter shaft 42 by the dog clutch D3, so that the main shaft is connected via the first speed transmission gear train. The power of 41 is transmitted to the countershaft 42. Similarly, when the dog clutch D1 is meshed with the fourth speed drive gear 54a, power is transmitted through the fourth speed transmission gear train, and when the dog clutch D1 is meshed with the fifth speed drive gear 55a, the fifth speed is changed. Power is transmitted through a high speed gear train.

  FIG. 5 is a sectional view taken along line BB in FIG. Since FIG. 5 is shown in a state where the cross section is developed in a plane, the transmission gear train from the first speed to the fifth speed is shown in a separated state.

  As shown in FIG. 5, a reverse shaft 56 is attached to the crankcase 6. The reverse drive gear 57 a is fixed to the main shaft 41 and rotates integrally therewith, and the countershaft 42 is rotatably mounted. A reverse idler gear 57c, that is, a reverse idler gear 57c that always meshes with the reverse driven gear 57b to form a reverse transmission gear train is mounted on the reverse shaft 56. The dog clutch D2 is engaged with the reverse driven gear 57b, and when these are engaged, the power of the main shaft 41 is reversely rotated by the reverse idler gear 57c and transmitted to the counter shaft 42.

  The counter shaft 42 is connected to the front wheels 2a and 2b and the rear wheels 3a and 3b as drive wheels shown in FIG. 1 via a power transmission member such as a chain (not shown), and the engine power is transmitted to the respective drive wheels. The

  The reverse shaft 56 is formed by a hollow shaft, and lubricating oil is supplied to the hollow hole. The reverse shaft 56 has a lubricating oil discharge hole for discharging the lubricating oil to the gear. . Further, an annular projection 58 is integrally provided on the reverse shaft 56 so as to rotatably support the reverse idler gear 57c so as not to be displaced in the axial direction. A washer 59 is mounted as an annular member on the end side of the rear end of the reverse idler gear 57c so as to restrict the axial displacement of the reverse idler gear 57c by the projection 58. Since the washer 59 is disposed between the reverse idler gear 57 c and the case 6, the washer 59 can be fixed to the reverse shaft 56 without forming a step on the reverse shaft 56. Accordingly, the reverse shaft 56 has substantially the same outer diameter except for the protruding portion 58, and the reverse shaft 56 can be manufactured with a small number of cutting steps.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, this intake device can be applied not only to all-terrain vehicles but also to other types of vehicles and general-purpose engines. The vaporizers 20a and 20b can be used regardless of the ventilation direction (downward ventilation type or lateral ventilation type) or the venturi (fixed or variable).

It is a perspective view which shows the vehicle in which a power transmission device is incorporated. It is the schematic which shows the vehicle power transmission device which is one embodiment of this invention mounted in the vehicle of FIG. It is sectional drawing which follows the AA line of FIG. It is sectional drawing of the state which looked at the cylinder head in FIG. 3 from the top. It is sectional drawing which shows the cross section which follows the BB line of FIG. 3 in an unfolded state.

Explanation of symbols

8 Cylinder 9 Cylinder head 13 Combustion chamber 14a Intake port 14b Intake port 15a Exhaust port 15b Exhaust port 16 Intake valve 17 Exhaust valve 18a Individual passage portion 18b Individual passage portion 19 Intake pipe 20a Vaporizer 20b Vaporizer 21 Intake passage 22 Intake passage

Claims (1)

An intake device for a four-cycle engine that performs intake and exhaust of an air-fuel mixture in a combustion chamber by an intake valve and an exhaust valve, each of which is opened and closed by a valve cam.
Two intake ports that are independently formed in the cylinder head without merging with each other and to which the intake valve is reciprocally mounted;
An intake pipe fixed to the cylinder head and formed with two individual passage portions communicating with each of the intake ports;
4 having two carburetors that are provided in each of the individual passage portions and supply an air-fuel mixture to each of two sets of intake passages constituted by the intake port and the individual passage portions. Cycle engine intake system.

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