JP2004076675A - Valve system and internal combustion engine equipped with the valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve system and an internal combustion engine having the valve system for realizing superior characteristic performance while reducing the size of the system. <P>SOLUTION: A swing arm 21 for engaging with a tip part is arranged in a stem end part of an intake-exhaust valve arranged at a prescribed narrow angle, and is journaled by arranging a base end part of the swing arm 21 outside the narrow angle. A roller tappet 22 having a shaft 24 parallel to a shaft of the base end part is arranged between the base end part and the tip part. A camshaft 11 is arranged in parallel on the opposite side of the intake-exhaust valve to the shaft of the roller tappet 22. A cam lobe is arranged so as to slidable in the shaft direction on the camshaft 11 by opposing the roller tappet 22. A cam 13 having a three-dimensional map is arranged in the cam lobe. An energizing means is arranged in the vicinity of the camshaft 11 for energizing the cam lobe in the camshaft direction so as to be capable of advancing and retreating. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve train for continuously and variably controlling a valve lift and an operating angle according to an accelerator opening in an internal combustion engine of a motorcycle or an automobile.
[0002]
[Prior art]
In this type of internal combustion engine, in order to improve the combustion efficiency, a variable phase method in which the valve opening / closing timing is shifted has been used, and a variable valve lift control by cam switching, a valve stop, and the like have been employed. In this cam switching method, two cams for low speed and high speed are prepared, and the cam is switched from a small one to a large one according to the engine output. These engines are premised on having a throttle valve in the intake pipe, and it is this throttle valve that reflects the driver's control intention, not the valve train.
[0003]
More recently, a system using a three-dimensional cam has been proposed in which a combination of variable phase and cam switching has begun to appear, and thereafter the operating angle and the lift amount are continuously varied. For example, there is a type in which a follow-up mechanism for a change in contact angle is provided at the top of a direct hit type cylindrical tappet, and a valve lift is continuously variable by sliding a three-dimensional cam in an axial direction.
[0004]
[Problems to be solved by the invention]
By the way, since this type of valve train has a slide drive mechanism for a three-dimensional cam, it is not always easy to reduce the size of the machine while ensuring intended performance characteristics. Further, the valve lift characteristics of the three-dimensional cam are closely related to the output characteristics of the engine, and setting parameters such as the shape of the cam is extremely important.
[0005]
In view of such circumstances, an object of the present invention is to provide a valve train that realizes excellent characteristic performance while reducing the size of the device, and an internal combustion engine provided with the valve train.
[0006]
[Means for Solving the Problems]
According to the valve gear of the present invention, a swing arm having a distal end engaged with a stem end of an intake / exhaust valve arranged at a predetermined included angle is provided, and a base end of the swing arm is disposed outside the included angle. A roller tappet having an axis parallel to the axis of the base end is provided between the base end and the tip, and the roller tappet is provided on the opposite side of the intake / exhaust valve with respect to the axis of the roller tappet. A camshaft is provided in parallel, a cam lobe disposed on the cam shaft so as to be slidable in the axial direction facing the roller tappet is provided, and a cam having a three-dimensional map is provided on the cam lobe, and the cam lobe is provided. An urging means for urging forward and backward in the camshaft direction is arranged near the camshaft.
[0007]
Further, in the valve gear of the present invention, there is provided a lubricant supply means for lubricating a contact portion between the roller tappet and the cam, and the lubricant supply means is provided in a housing of the roller tappet in a swing arm. An opening, from which the lubricant is supplied to the contact portion in a tangential direction of the roller tappet.
[0008]
Further, the valve gear of the present invention converts the rotation of the transmission gear rotationally driven by the drive motor into an axial sliding motion via a screw feed mechanism, and the sliding motion causes the cam to slide in the cam axial direction. In the valve gear, the transmission gear and the screw feed mechanism are arranged close to each other, and the bearing of the transmission gear and the screw feed mechanism are arranged so as to overlap at an axial position. .
[0009]
In the valve gear of the present invention, a slide shaft that slides through the screw feed mechanism is provided separately from the cam shaft, and the slide shaft is supported by a bearing of the transmission gear through the screw feed mechanism. , Supported by another plurality of bearings.
[0010]
Further, the valve gear of the present invention is formed so that the cam height and the cam working angle in an engine having an intake pipe of a predetermined length are continuously changed, and rotate integrally with the camshaft and move in the axial direction relative to the camshaft. A cam valve configured to be movable, and a valve operating device including a valve lifter pressed against the cam surface to advance and retract the valve, wherein the cam has a cam surface inclined in an axial direction of the cam shaft, When the cam slides in the axial direction of the camshaft, the working angle of the cam is made proportional to the engine speed or the vehicle speed, and the valve lift and the valve operating angle are continuously and continuously variably controlled. And
[0011]
Further, in the valve gear according to the present invention, a ratio of a maximum angle and a minimum angle of the operating angle of the cam is substantially three times or more.
[0012]
Further, the internal combustion engine of the present invention is an internal combustion engine in which intake and exhaust are controlled by an intake valve and an exhaust valve, and the valve train according to any one of claims 1 to 6 on an intake side and an exhaust side. A device is provided.
[0013]
According to the present invention, for example, the base end of the swing arm is disposed outside the included angle of the stem of the intake / exhaust valve to support the shaft, and a roller tappet having an axis parallel to the base end is provided with the base end and the tip. The cam shaft is provided in parallel with the roller tappet on the side opposite to the intake / exhaust valve with respect to the shaft of the roller tappet. In particular, the camshaft is arranged at a position where the cam and the plug hole do not interfere with each other in the DOHC engine, and the valve stem is arranged inside the camshaft, whereby the engine can be made compact.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a valve train according to the present invention and an internal combustion engine including the same will be described with reference to the drawings.
(1st Embodiment)
The valve gear according to the present invention can be effectively applied to various gasoline engines mounted on a motorcycle or a four-wheeled vehicle. In this embodiment, for example, as shown in FIG. I do.
[0015]
Here, first, the overall configuration of the motorcycle 100 according to the present embodiment will be described. In FIG. 1, two front forks 103 supported rotatably left and right by a steering head pipe 102 are provided at a front portion of a vehicle body frame 101 made of steel or an aluminum alloy material. A handlebar 104 is fixed to the upper end of the front fork 103, and has grips 105 at both ends of the handlebar 104. A front wheel 106 is rotatably supported at a lower portion of the front fork 103, and a front fender 107 is fixed so as to cover an upper portion of the front wheel 106. The front wheel 106 has a brake disc 108 that rotates integrally with the front wheel 106.
[0016]
A swing arm 109 is swingably provided at the rear of the body frame 101, and a rear shock absorber 110 is mounted between the body frame 101 and the swing arm 109. A rear wheel 111 is rotatably supported at the rear end of the swing arm 109. The rear wheel 111 is driven to rotate via a driven sprocket 113 around which a chain 112 is wound.
[0017]
An air-fuel mixture is supplied to an engine unit 1 (solid line portion) mounted on the body frame 101 from an intake pipe 115 connected to an air cleaner 114, and exhaust gas after combustion is exhausted through an exhaust pipe 116. The air cleaner 114 is installed behind the engine unit 1 and in a large space below the fuel tank 117 and the seat 118 to secure a capacity. Therefore, the intake pipe 115 is connected to the rear side of the engine unit 1, and the exhaust pipe 116 is connected to the front side of the engine unit 1. Further, a fuel tank 117 is mounted above the engine unit 1, and a seat 118 and a seat cowl 119 are continuously provided behind the fuel tank 117.
[0018]
Here, an accelerator motor, which will be described later, is mounted on a predetermined portion of the cylinder head 2 to the cylinder head cover 2a of the engine unit 1. The accelerator motor protrudes from the side of the cylinder head cover 2a, for example, as shown in the figure. In this case, an accelerator motor portion is provided in a concave portion provided at a lower portion of the fuel tank 117, and the fuel tank 117 and the cylinder head cover 2a are arranged so as not to interfere with each other.
[0019]
1, reference numeral 120 denotes a headlamp; 121, a meter unit including a speedometer, a tachometer or various indicator lamps; and 122, a rearview mirror supported on the handlebar 104 via a stay 123. A main stand 124 is attached to the lower part of the vehicle body frame 101 so as to be swingable, so that the rear wheel 111 can be grounded or lifted off the ground. The vehicle body frame 101 extends obliquely rearward and downward from a head pipe 102 provided at a front portion, curves so as to wrap around a lower portion of the engine unit 1, and forms a pivot 109 a which is a pivot support portion of a swing arm 109. It is connected to the tank rail 101a and the seat rail 101b.
[0020]
The body frame 101 is provided with a radiator 125 in parallel with the body frame to avoid interference with the front fender 107, and a cooling water hose 126 is provided from the radiator 125 along the body frame 101, and an exhaust pipe 116 is provided. And is communicated with the engine unit 1 without interference.
[0021]
Next, FIG. 2 is a cross-sectional view of a main part of the device of the present invention, and FIG. 3 is a cross-sectional view taken along lines AA and BB of FIG. In this embodiment, the engine unit 1 is a parallel two-cylinder engine, and each cylinder has two valves (ie, four valves) on the intake side (IN) and the exhaust side (EX). A cylinder head 2 is arranged above a piston that reciprocates up and down in the cylinder, and a valve gear is accommodated in the cylinder head 2.
[0022]
The valve gear of the present embodiment includes a cam / camshaft unit 10 arranged along the direction in which cylinders are arranged on the intake side, a valve lifter unit 20 arranged below the cam / camshaft unit 10, It includes a valve unit 30 that controls intake air, and an accelerator shaft unit 40 that displaces a cam according to the accelerator opening.
[0023]
On the exhaust side, a cam / camshaft unit 10 _Ex having substantially the same configuration as the intake side, a valve lifter unit 20 _Ex disposed below the cam / camshaft unit 10 _Ex , and a valve for exhaust control Unit 30 _Ex . Hereinafter, these units will be mainly described on the intake side, but the exhaust side has the same configuration.
[0024]
The cam 13 and the cam 13 _Ex of the cam / camshaft unit 10 and the cam / camshaft unit 10 _Ex variably control the valve lift amount, operating angle and lift timing of the intake valve 31 and the exhaust valve 31 _{Ex in} a stepless manner. It is configured. The camshaft unit 40 includes an accelerator shaft unit 40 for displacing these cams in accordance with the accelerator opening. In this embodiment, the camshaft unit 10 is disposed between the intake cam / camshaft unit 10 and the exhaust cam / camshaft unit 10 _Ex. Is done. That is, the accelerator shaft unit 40 is shared by the intake side and the exhaust side.
[0025]
In the cam / camshaft unit 10, the camshaft 11 is rotatably supported by the cylinder head 2 via a bearing 12 (FIG. 3). A cam 13 to be described later is slidably mounted on the camshaft 11 in the axial direction. In this example, the camshaft 11 has, for example, three ball splines 11a, and a linear motion through the balls 14 is guided by the guide. (Linear motion). The camshaft 11 has a hollow structure, and a lubricating oil passage is formed inside the hollow, so that the cam 13 and the like can be lubricated.
[0026]
A sprocket 15 is fixed to one end of the camshaft 11. A sprocket 15 _Ex is also fixed to one end of the camshaft 11 _Ex on the exhaust side. As shown in FIG. 4, the sprocket 15 _Ex and the sprocket 15 _Ex are fixed to one end of a crankshaft (not shown). A cam chain 4 is wound around the drive sprocket 3. In addition, as shown in FIG. 4, a chain guide 5, a chain tensioner 6, a tensioner adjuster 7, and the like are included so that the cam chain 4 can travel properly.
[0027]
Here, the cam 13 and the cam 13 _Ex are configured as “three-dimensional cams”, and are provided one each on the intake side and the exhaust side of each cylinder. As shown in FIG. 3, a cam portion gently inclined in the longitudinal direction (the axial direction of the camshaft 11) extends and is formed into a shape that continuously changes the valve lift amount. In this case, the cam working angle and the lift timing change simultaneously with the cam height, that is, the cam working angle increases as the valve lift increases, and the valve lift timing can also be changed.
[0028]
In this example, the valve lifter unit 20 includes a swing arm 21 and a tappet roller 22 as a valve lifter. It is swingably supported by the shaft 23. As shown in FIG. 5, the tip of the swing arm 21 branches into two branches so as to contact two intake valves in each cylinder, that is, a single swing arm 21 drives two intake valves. It has become.
[0029]
As shown in FIG. 2, the base end of the swing arm 21, that is, the swing arm shaft 23 is located below the camshaft 12 and outside the included angle (V bank) set by the valve stem of the intake / exhaust valve. Be placed. A plug hole 8 for inserting and removing a spark plug is formed substantially at the center of the V bank.
[0030]
A tappet roller 22, which is a rotary sliding portion, is rotatably supported in the middle of the swing arm 21 via a pin 24. The outer peripheral surface of the tappet roller 22 is typically formed in an arc shape (R shape), and comes into point contact with the cam 13. The pin 24 is arranged in parallel with the swing arm shaft 23, and the camshaft 11 is arranged on the opposite side of the pin 24 from the intake valve.
[0031]
On the exhaust side, the swing arm 21 _Ex is swingably supported by the swing arm shaft 23 _Ex such that one end thereof contacts an upper end portion (valve stem end) of the exhaust valve. The tip of the swing arm 21 _Ex is bifurcated to contact two exhaust valves in each cylinder (see FIG. 5), and the two swing valves are driven by a single swing arm 21 _Ex. ing.
[0032]
In the middle of the swing arm 21 _Ex , a tappet roller 22 _Ex, which is a rotary sliding portion, is rotatably supported via a pin 24 _Ex . The outer peripheral surface of the tappet roller 22 _Ex is typically formed in an arc shape (R shape), and comes into point contact with the cam 13 _Ex .
[0033]
Here, there is provided a lubricant supply means for lubricating a contact portion between the tappet roller 22 ( _22Ex ) and the cam 13 ( _13Ex ). The lubricant supply means includes a tappet roller 22 _{(22 Ex)} opening 25 which is opened in the accommodating section of _{(25 Ex)} in the swing arm 21 _{(21 Ex)} as shown in FIG. 2 or FIG. 5, the opening and supplies the lubricant to the tangential direction of the tappet roller 22 _{(22 Ex)} to the contact site from ₂₅ (25 _Ex). Note that communicates with the opening 25 _{(25 Ex)} to the swing arm shaft 23 _{(23 Ex)} in the oil passage 26 for pumping lubricant to the opening _{25 (25 Ex) (26 Ex} ) are formed.
[0034]
In the valve unit 30, each valve stem 31a includes two intake valves 31 guided by a valve guide 32. At the end of each valve stem 31a, there is a tappet shim 33 in contact with the pressing portion 21a of the swing arm 21, and a valve spring 36 is mounted between the valve retainer 34 and the spring seat 35.
[0035]
The cam / camshaft unit 10 _Ex , the valve lifter unit 20 _Ex, and the valve unit 30 _Ex on the exhaust side have the same basic configuration as each unit on the intake side as described above, but the cam 13 of the cam / camshaft unit 10 _Ex The specifics of _Ex are different from those of the cam 13.
[0036]
The accelerator shaft unit 40 includes a camshaft 11 and an accelerator shaft 41 arranged parallel to the camshaft 11 _Ex, and an accelerator fork 42 fixed to the accelerator shaft 41 and connected to the cam 13 and the cam 13 _Ex . The accelerator shaft 41 is supported by the cylinder head 2 so as to be slidable in the axial direction, and is engaged at one end with a driven gear 43 (wheel) via a screw respline 41a. The driven gear 43 is rotatably supported by the cylinder head 2 and meshes with a drive gear 46 (worm) fixed to an output shaft of an accelerator motor 45.
[0037]
The accelerator fork 42 extends toward the camshaft 11 and the camshaft 11 _{Ex in a} direction orthogonal to the accelerator shaft 41, and each of the bifurcated tips is rotatable to the end of the cam 13 and the cam 13 _Ex via the bearing 47. Engages with the fork guide 48 mounted on the fork guide. Accordingly, the cam 13 and the cam 13 _Ex slide along the camshaft 11 and the camshaft 11 _Ex , respectively, in synchronization with or in synchronization with the sliding of the accelerator shaft 41 in the axial direction.
[0038]
The rotation of the driven gear 43 as a transmission gear rotationally driven by the accelerator motor 45 is converted into an axial sliding motion of the accelerator shaft 41 via a screw feed mechanism (screw spline 41a). 13 is slid in the cam axis direction. In this case, as shown in FIG. 3, the driven gear 43 and the screw feed mechanism are arranged close to each other, and the bearing 49A of the driven gear 43 and the screw feed mechanism are arranged so as to overlap at the axial position.
[0039]
An accelerator shaft 41 that slides via a screw feed mechanism is provided separately from the camshaft 11 and the camshaft 11 _Ex, and the accelerator shaft 41 is supported by a bearing 49A via the screw feed mechanism. In this case, the accelerator shaft 41 is supported by still another plurality of bearings 49B and 49C.
[0040]
Here, a phase sensor unit 50 is provided at the other end of the camshaft 11. The phase sensor unit 50 includes a pin 51 implanted at the other end of the camshaft 11 and a phase sensor 52 that detects the pin 51 and obtains an output signal.
[0041]
In the above configuration, when the accelerator grip (or the accelerator pedal) is operated, the accelerator motor 45 operates, and the rotation of the output shaft causes the accelerator shaft 41 to slide. For example, when the engine is running at a low speed, the tappet roller 22 is in contact with the cam 13 at a position where the cam height is low, as shown in FIG. On the exhaust side, the tappet roller 22 _Ex abuts on the cam 13 _{Ex at} a position where the cam height is low. When acceleration is performed in this state, that is, when the accelerator is opened, the driven gear 43 is rotated by the operation of the accelerator motor 45, and the accelerator shaft 41 slides rightward in the drawing.
[0042]
As a result, the cam 13 and the cam 13 _Ex slide similarly to the right along the camshaft 11 and the camshaft 11 _Ex via the accelerator fork 42 in conjunction with the movement of the accelerator shaft 41, respectively. At this time, the slide amount and speed of the cam 13 and the cam 13 _Ex correspond to the opening degree and opening speed of the accelerator. As the cams 13 and 13 _Ex slide, the tappet rollers 22 and 22 _Ex gradually come into contact with a portion having a high cam height, whereby the valve lift increases according to the lift characteristics of the cams 13 and 13 _Ex . On the other hand, by returning the accelerator at the time of deceleration, the valve lift amount is reduced by the operation opposite to the above.
[0043]
Here, in the above-described valve gear or the internal combustion engine of the present invention, in particular, the camshaft 11, the swing arm shaft 23, the pin 24, and the like are arranged outside the V bank as is clear from FIG. The same applies to the exhaust side. Thus, the height of the cylinder head 2 can be reduced, and the front-rear length of the cylinder head 2 can be shortened by lowering the cam ridge height by setting the arm ratio of the swing arm 21. 2 can be made compact.
[0044]
In this case, since the tappet roller 22 is disposed between the valve stem 31a and the swing arm shaft 23, the arm ratio of the swing arm 21 is larger than 1. The same applies to the exhaust side. As a result, the height of the cam lobe is reduced, the inclination angle of the cam lobe in the cam lobe in the axial direction is made small (gentle), the sliding movement of the cam 13 is smooth, and the sliding direction applied to the entire rotating and sliding valve train. And the durability is improved. Further, the width of the tappet roller 22 can be reduced, the total weight of the tappet can be reduced, and particularly, high rotation and high acceleration can be achieved to achieve high output.
[0045]
Further, according to the lubricant supply means, the lubricant is applied in all phases to the contact portion between the tappet roller 22 ( _22Ex ) and the cam 13 ( _13Ex ), and the lubricity is remarkably improved. Accordingly, the cam 13 is smoothly moved in the axial direction while maintaining the point-contact engagement between the cam 13 and the tappet roller 22, and high durability can be ensured also in this respect.
[0046]
In a three-dimensional cam such as the cam 13, the tappet roller 22, which is a mating member that comes into sliding contact with the three-dimensional cam, makes point contact with the three-dimensional cam, which affects durability. Therefore, it is desired to increase the diameter of the tappet roller 22. In the present invention, the tappet roller 22 is deviated from the valve axis and disposed between the two intake valves, thereby achieving both a large diameter and a compact size. Further, a large space occupied by the sliding cam 13 (13 _Ex ) can be secured on the valve shaft and the tappet roller 22. As a result, the cam 13 is large in the axial direction and the height can be reduced, so that the upper portion of the accelerator motor 45 can be mounted.
[0047]
Further, the driven gear 43 and the screw feed mechanism are arranged close to each other, and the bearing 49A of the driven gear 43 and the screw feed mechanism are arranged so as to overlap in the axial position. Thus, by arranging these members collectively, compactness can be achieved. Then, when the accelerator shaft 41 is slid, blurring and rattling are suppressed to ensure a smooth operation.
[0048]
Further, the accelerator shaft 41 is provided separately from the camshaft 11 and the camshaft 11 _Ex, and the accelerator shaft 41 is supported by a bearing 49A via a screw feed mechanism. Further, the accelerator shaft 41 is supported by a plurality of other bearings 49B and 49C. When the accelerator shaft 41 is slid, a smooth movement is assured by suppressing blurring and rattling.
[0049]
(Second embodiment)
Next, a second embodiment according to the present invention will be described. Note that members that are the same as or correspond to those in the above-described first embodiment are denoted by the same reference numerals, and will be described with reference to the drawings. FIG. 6 is a sectional side view of a main part according to the present embodiment. The basic configuration in this embodiment is substantially the same as in the first embodiment, and a description thereof will be omitted.
[0050]
In the present embodiment, the valve lift characteristic is continuously and variably controlled using a three-dimensional cam. In this case, the engine speed and the intake working angle are adjusted so that the maximum intake inertia effect can be obtained in the practical running rotation range even when the intake pipe length is fixed. To set.
[0051]
By the way, when the intake working angle is constant, it is necessary to change the intake pipe length in order to always maximize the intake inertia effect at each engine speed. For this purpose, for example, a method of continuously changing the value by sliding the intake pipe or changing the value in a stepwise manner using a valve or the like is used. In the present invention, the valve lift characteristics can be adapted to the engine output by using a three-dimensional cam. In the present embodiment, the intake pipe length can be continuously varied even if the intake pipe length is fixed, particularly by suitably setting the intake working angle. In this case, the same effect as in the case of the above is obtained.
[0052]
Here, the formula of the engine speed at which the maximum intake inertia effect is obtained is shown.
_{N = aθ s / 24L s (} 1)
Where L _s ≒ π / 2 · √ (LV / F), L = l + Δl
Here, a: sound speed = 340 [m / s] (20 ° C.); N: engine speed [rpm]; θ _s : effective valve opening angle [deg]; L _s : equivalent pipe length [m]; L: pipe length [m]; F ... intake pipe cross-sectional area ^[m 2] (independent port in the case of ^{F = 2 · πd 2/4} ); V ... stroke volume ^[m 3]; l ... actual tube length [m]; Δl ... tube The end correction length [m]. In addition, as shown in FIG. 6, the intake pipe length L includes the intake port 9.
[0053]
Assuming that K = a / 24L _s from the above equation and that the temperature and the pipe length are fixed, K is constant, so that the engine speed N and the effective valve opening angle (operating angle of the intake valve) θ _s are in a proportional relationship. Become. Therefore, by setting the effective opening angle theta _s to be proportional to the engine speed N, will always be the maximum intake inertia effect can be obtained within the range. In addition, the intake pipe including the intake port has an average atmospheric pressure or slightly negative pressure, regardless of the engine speed.
[0054]
In the engine shown in FIG. 6, when the engine specifications are 650 cc in parallel two cylinders and vehicle speed V ₁₀₀₀₀ = 220 km / h (maximum speed at the sixth speed), the engine speed N (vehicle speed) and the effective valve opening angle θ The relationship of _s is as shown in FIG. FIG. 8 shows the lift characteristics of the cam 13 for obtaining the engine characteristics shown in FIG.
[0055]
In the example of FIG. 7, θ _s = 80 ° at a speed of 60 km / h (N ≒ 2730 rpm), and θ _s = 240 ° at a speed of 180 km / h (N ≒ 8180 rpm). In this rotational speed range, the engine rotational speed N and the effective valve opening angle θ _s are set so as to have almost the maximum intake inertia effect, whereby the maximum intake inertia effect is obtained in the practical rotation range of the top stage (sixth speed), Almost flat torque can be achieved.
[0056]
Similarly, for example, when applied to a light four-wheeled vehicle, the relationship between the engine speed N (vehicle speed) and the effective valve opening angle θ _s when the engine specification is 660 cc in parallel two cylinders and the vehicle speed V ₁₀₀₀ = 20 km / h. Is as shown in FIG. In this case, if variable effective opening angle theta _s up to 3 _{times, θ s = 80 °; 40km} / h from θ _s = 240 °; put out 120 km / h and the maximum speed gear position (fourth speed ... 5-speed In many cases, the fifth speed of a four-wheeled vehicle becomes an overtop), and can cover most of the region from near the lower limit of the top throw to near the maximum speed.
[0057]
Therefore, by setting the effective valve opening angle θ _s to be proportional to the engine speed N and changing the effective valve opening angle θ _s to about three times, the maximum intake inertia effect can be obtained in most practical rotation ranges. In addition, the length of the intake pipe can be shortened on the high-speed side, and the size of the engine can be reduced. In particular, in a four-wheeled vehicle in which the length of the intake pipe is set to be long in order to produce a low-speed output, the effect of downsizing is extremely great.
[0058]
Even if the cross-sectional area and length of the intake pipe are fixed in this manner, the operating angle (that is, the opening time of the intake valve) changes in proportion to the engine speed. A high intake inertia effect can be maintained. As a result, the suction filling efficiency of the combustion chamber is kept high. That is, flat torque characteristics without valleys can be obtained over the entire range of the engine speed.
[0059]
In addition, by setting the intake pipe length so that the intake inertia effect is maximized, a substantially maximum torque can be obtained over the entire engine speed range. On the other hand, since the valve opening time changes according to the engine speed, the intake inertia effect can be obtained even if the intake pipe is shortened in consideration of the sectional area of the intake pipe.
[0060]
Furthermore, by varying the effective opening angle theta _s up to three times or more, practical speed region of the engine is ensured widely. As a result, regardless of the speed of the transmission (including the automatic transmission and the continuously variable transmission), the speed range covered by each speed is widened, and a vehicle with a wide driving range and high practicality can be realized. it can.
[0061]
As described above, the present invention has been described with various embodiments. However, the present invention is not limited to only these embodiments, and can be modified within the scope of the present invention.
For example, in the above embodiment, an example of a two-cylinder engine has been described, but the present invention can be effectively applied to a single-cylinder engine or an engine having three or more cylinders.
[0062]
【The invention's effect】
As described above, according to the present invention, in this type of valve train, the valve lift, the operating angle, and the lift timing are steplessly variably controlled according to the accelerator opening. In this case, for example, the base end of the swing arm is arranged outside the included angle of the stem of the intake / exhaust valve to support the shaft, and a roller tappet having an axis parallel to the base end is provided between the base end and the front end. And a cam shaft is provided in parallel with the shaft of the roller tappet on the side opposite to the intake / exhaust valve. By arranging the cam shaft at a position where the cam and the plug hole do not interfere with each other and arranging the valve stem inside the cam shaft, the engine can be made compact.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a motorcycle including a periphery of an engine according to an application example of the present invention.
FIG. 2 is a sectional side view of a main part of the valve gear according to the first embodiment of the present invention.
FIG. 3 is a sectional view taken along lines AA and BB in FIG. 2;
FIG. 4 is a diagram showing a camshaft rotation drive system according to the valve train of the present invention.
FIG. 5 is a sectional view taken along line CC of FIG. 2;
FIG. 6 is a sectional view of a main part of a valve train according to a second embodiment of the present invention.
FIG. 7 is a diagram illustrating a relationship between an engine speed and an effective valve opening angle according to a second embodiment of the present invention.
FIG. 8 is a diagram showing a lift characteristic of a cam according to a second embodiment of the present invention.
FIG. 9 is a diagram showing a relationship between another engine speed and an effective valve opening angle in the second embodiment of the present invention.
[Explanation of symbols]
1 engine unit, 2 cylinder head, 2a cylinder head cover, 3 drive sprocket, 4 cam chain, 5 chain guide, 6 chain tensioner, 7 tensioner adjuster, 8 plug all, 9 intake port, 10, 10 _Ex cam / cam shaft unit, Reference Signs List 11 camshaft, 12 bearing, 13 cam, 20, 20 _Ex valve lifter unit, 21 swing arm, 22 tappet roller, 23 swing arm shaft, 30, 30 _Ex valve unit, 31 intake valve, 32 valve guide, 33 tappet shim, 34 tappet Retainer, 35 spring seat, 36 valve spring, 40 accelerator shaft unit, 41 accelerator shaft, 42 accelerator fork, 43 driven gear, 45 accelerator motor, 46 drive gear, 50 phase sensor unit, 51 pins, 52 phase sensor.

Claims (7)

Along with a swing arm having a distal end engaged with the stem end of the intake / exhaust valve arranged at a predetermined included angle, the base end of the swing arm is arranged outside the included angle and pivoted,
A roller tappet having an axis parallel to the axis of the base section is provided between the base section and the tip section, and a cam shaft is provided in parallel with the axis of the roller tappet on a side opposite to the intake / exhaust valve. ,
A cam lobe disposed on the cam shaft slidably in the axial direction opposite to the roller tappet is provided, and a cam having a three-dimensional map is provided on the cam lobe,
A valve gear, wherein an urging means for urging the cam lobe so as to be able to advance and retreat in the cam shaft direction is disposed near the cam shaft. A lubricant supply unit for lubricating a contact portion between the roller tappet and the cam,
The lubricant supply means includes an opening provided in the accommodation portion of the roller tappet in the swing arm, and supplies the lubricant from the opening to the contact portion in a tangential direction of the roller tappet. The valve train according to claim 1. A valve operating device that converts the rotation of a transmission gear rotationally driven by a drive motor into an axial sliding motion via a screw feed mechanism, and causes the cam to slide in the cam axial direction by the sliding motion. ,
A valve gear, wherein the transmission gear and the screw feed mechanism are arranged close to each other, and the bearing of the transmission gear and the screw feed mechanism are arranged so as to overlap at an axial position. A slide shaft that slides via the screw feed mechanism is provided separately from the cam shaft, and the slide shaft is supported by the bearing of the transmission gear via the screw feed mechanism and supported by another plurality of bearings. The valve train according to claim 3, wherein: A cam having an intake pipe of a predetermined length and having a cam height and a cam operating angle which are continuously changed, are integrally rotated with a cam shaft, and are relatively movable in the axial direction; A valve lifter that is pressed against the cam surface to advance and retract the valve,
The cam has a cam surface that is inclined in the axial direction of the camshaft, and the cam slides in the axial direction of the camshaft to make the working angle of the cam proportional to the engine speed or the vehicle speed. A valve train wherein a lift amount and a valve operating angle are continuously and continuously variably controlled. The valve gear according to claim 5, wherein a ratio of a maximum angle to a minimum angle of the working angle of the cam is substantially three times or more. An internal combustion engine that controls intake and exhaust by an intake valve and an exhaust valve,
An internal combustion engine comprising the valve train according to any one of claims 1 to 6 on an intake side and an exhaust side.

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