CN2716511Y

CN2716511Y - Valve timing changeable mechanism for four-stroke engine

Info

Publication number: CN2716511Y
Application number: CN 200420045903
Authority: CN
Inventors: 胡涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-05-14
Filing date: 2004-05-14
Publication date: 2005-08-10
Anticipated expiration: 2014-05-14

Abstract

The utility model discloses a valve timing changeable mechanism for a four-stroke engine, comprising a valve cam and a valve sprocket. The valve sprocket is moveably sheathed on a valve cam shaft, and the inner of a blind hole of the valve cam shaft is provided with a spring and a movable pin shaft in sequence. Two keys are fixed to the pin shaft, and the space of two keys is more than the width of the valve sprocket. The two keys can slide in an elongated slot hole on the valve cam shaft. A plurality of key grooves are distributed along the circumference of the center hole of the valve sprocket, and the size of the key groove is matched with the key. The utility model can act through the pin shaft, and the valve sprocket and the valve cam shaft can generate the relative rotation, which realizes the angular change between the valve cam shaft and a crankshaft, so that the valve timing is changed, that is the opening time and the closing time of an ingress-exhaust valve is changed. Thus the utility model can match with the working operation condition of the engine, and thus the engine can obtain larger power output both in the low-speed and the high-speed extents. Besides, the utility model can improve the fuel economy and reduce the exhaust of the waste gas contaminant.

Description

A kind of port timing changeable mechanism of four stroke engine

Technical field

The utility model relates to the distribution device of a kind of distribution device of four stroke engine, particularly phase variable.

Background technique

In four stroke engine, all design has distribution device, its function is the working procedure of being carried out according in ignition order between cylinder and the cylinder, in time opening and closing intake valve and exhaust valve, correspondingly guarantee to fill fresh charge (fuel mixture or air) in the cylinder, and the waste gas in the cylinder is got rid of.Distribution device comprises that mainly camshaft, valve reach the parts of relevant with it assurance valve switch.Because the opened and closed positions of valve is relevant with position of piston, position of piston is relevant with crank angle, therefore can represent the switching time of valve with crank angle, port timing that Here it is.Represent switching time of valve with crank angle, and represent the opening angle and the closing angle of valve, the valve timing diagram of Here it is motor with circular arc.As shown 1.Distribution device keeps certain port timing by distribution chain, distribution sprocket wheel or timing gear etc. and bent axle, and the coordinated movement of various economic factors mutually.

As can be seen, the switching time of valve is in top dead center and lower dead center from the valve timing diagram, but have bigger in advance and lag behind.Because gas has quality, just certainly exist inertia.This effect of inertia is especially obvious to gas, and gas can not flow suddenly and can not stop suddenly.When air inlet, air-flow needs to quicken, so when valve was just opened, induction air flow ratio was very slow.For this reason, must before top dead center, open intake valve, for inlet stream is quickened to prepare.When aspirating stroke began, the intake valve aperture was big, made inflation smooth, sufficient.After this, piston runs to lower dead center and begins up the time, and intake valve is still being opened, and induction air flow ratio at this moment is still very big, can utilize the inertia of air inlet to advance some mixed gass, inertia air inlet that Here it is more.Thereby make burning more abundant, improve power, reduce discharging.On the contrary, exhaust valve is opened ahead of time, and waste gas is discharged.And exhaust valve closes late, because exhaust stroke is at the end, inner pressure of air cylinder still is higher than atmospheric pressure, and utilize the inertia exhaust make waste gas as much as possible sucking-off go and get rid of clean.

The effect of valve cam is the opening and closing that make valve in good time, and the molded lines of cam has just determined the switching time of inlet and outlet doors, that is to say that port timing depends on the molded lines of valve cam.Port timing is most important for the influence of engine performance.

In design in the past, distribution sprocket wheel (or timing gear) is changeless with being connected of valve cam.When assembling, make the certain timing angle of maintenance between bent axle and the distribution sprocket wheel, and connect by the distribution chain.At this moment, the opening and closing angle of valve is fixed, and port timing is certain, i.e. the opening angle in advance of intake valve and lag behind to close the opening angle in advance of angle and exhaust valve and lag behind and close the angle and fix, only relevant with the rotational position of bent axle, and irrelevant with the rotating speed of bent axle.So, then the peak output output value of motor can only be in a certain speed range, and in other speed range, then power decline is more serious.The four-stroke autobicycle more as present application, its maximum power point (mpp) is mostly between 7500～9500rpm.But in urban road, its groundwork speed range is many, and in this interval, the output power and the moment of torsion of motor are relatively low between 4000～6000rpm, and the burning of motor is insufficient, and fuel economy is poor, and it is also high to discharge pollutants.At this moment just need slow-speed of revolution output motor.But when travelling on open road, the engine speed and the speed of a motor vehicle that need are higher, just need start function that higher power output is arranged when high speed.

Summary of the invention

The purpose of this utility model provides a kind of port timing changeable mechanism of four stroke engine, makes motor can both obtain bigger power output in low speed and high-speed range, and improves fuel economy, reduces the discharging of exhaust emission.

The technological scheme that its technical problem that solves the utility model adopts is:

A kind of port timing changeable mechanism of four stroke engine, comprise valve cam and distribution sprocket wheel, described distribution sprocket wheel movable set is on distribution cam axle, spring and bearing pin movably are housed in the blind hole of distribution cam axle successively, be fixed with two keys on the described bearing pin, the spacing of this two key is greater than the width of distribution sprocket wheel, and described two keys can slide in the elongated slotted eye on distribution cam axle, a plurality of keyways are circumferentially arranged, its size and key coupling on the center hole of described distribution sprocket wheel.

The beneficial effects of the utility model are: by being arranged on the removable bearing pin action on the distribution cam axle, make between distribution sprocket wheel and the distribution cam axle and produce relative rotation, realize producing between distribution cam axle and the bent axle variation of angle, to change port timing, promptly change the opening and closing moment of inlet and outlet door, make it to be complementary with the work operating mode of motor, thereby export higher power, make burning more abundant, save fuel consume, reduce discharging.

Description of drawings

Below in conjunction with drawings and Examples the utility model is further specified.

Fig. 1 is the valve timing diagram of motor;

Fig. 2 is a structural representation of the present utility model;

Fig. 3 is the structural representation of distribution sprocket wheel;

Fig. 4 is the A-A sectional view of Fig. 2;

Fig. 5 is that bearing pin moves the structural representation when causing port timing to change;

Fig. 6 is the B-B sectional view of Fig. 5.

Embodiment

With reference to Fig. 2, a kind of port timing changeable mechanism of four stroke engine, comprise valve cam 6 and distribution sprocket wheel 5, distribution sprocket wheel 5 movable sets are on distribution cam axle 61, spring 4 and bearing pin 3 movably are housed in the blind hole 62 of distribution cam axle 61 successively, be fixed with the key 1,2 of transmitting torque on the bearing pin 3, the spacing of this two key 1,2 is greater than the width W of distribution sprocket wheel 5, and described two keys 1,2 can slide in the elongated slotted eye 63 on distribution cam axle.Under external force, removable bearing pin 3 and key 1, key 2 can move back and forth along elongated slotted eye 63 together.

With reference to Fig. 3, a plurality of keyways 51 are circumferentially arranged on the center hole of distribution sprocket wheel 5, its size is complementary with key 1,2, and the angle between the number of keyway 51 and per two keyways is design modification as required.

With reference to Fig. 4, Fig. 5, Fig. 6, working procedure of the present utility model is: at first utilize engine ignition pulse signal or alternate manner detection of engine rotational speed N 1, and N1 passed to car-mounted computer (or single-chip microcomputer), compare with predefined a certain rotational speed N 0 in the computer.(1) when N1＜N0, computer does not have instruction output, and key 1 is transmitting torque between distribution cam axle 61 and distribution sprocket wheel 5; (2) when N1＞N0, computer sends instruction opens solenoid valve, and pressure oil is in oil circuit flows into the blind hole 62 of distribution cam axle 61.Under the effect of pressure oil, removable bearing pin 3 moves as piston, drives key 1 and key 2 and moves to illustrated right side.Because the spacing of key 1 and key 2 is slightly larger than the width W of distribution sprocket wheel 5, shift out the keyway 51 of distribution sprocket wheel 5 when key 1 after, under the drive of distribution chain, distribution sprocket wheel 5 has produced and has relatively rotated.Subsequently, key 2 moves forward, and inserts adjacent keyway, at this moment key 2 beginning transmitting torques.In this process, distribution cam axle 6 has turned over an angle relatively, is exactly the angle θ between 5 liang of keyways of distribution sprocket wheel.Thereby realized the change of port timing.(3) when rotating speed reduces N1＜N0, closed electromagnetic valve, oil pressure reduces, and under the effect of spring 4, removable bearing pin 3 is moved to the left, and key 2 shifts out the keyway 51 of distribution sprocket wheel 5, and because action of inertia, distribution sprocket wheel 5 produces relative rotation.Subsequently, key 1 continues to move to the left, inserts adjacent keyway, the state when getting back to low speed.

The utility model is by being arranged on removable bearing pin 3 actions on the distribution cam axle, make between distribution sprocket wheel and the distribution cam axle and produce relative rotation, realize producing between distribution cam axle and the bent axle variation of angle, to change port timing, promptly change the opening and closing moment of inlet and outlet door, make it to be complementary with the work operating mode of motor, thereby export higher power, make burning more abundant, save fuel consume, reduce discharging.

Claims

1. the port timing changeable mechanism of a four stroke engine, comprise valve cam (6) and distribution sprocket wheel (5), it is characterized in that: distribution sprocket wheel (5) movable set is on distribution cam axle (61), spring (4) and bearing pin (3) movably are housed in the blind hole (62) of distribution cam axle (61) successively, be fixed with two keys (1 on the described bearing pin (3), 2), this two key (1,2) spacing is greater than the width of distribution sprocket wheel (5), described two keys (1,2) can in the elongated slotted eye (63) on the distribution cam axle (61), slide, a plurality of keyways (51) are circumferentially arranged, its size and key (1 on the center hole of described distribution sprocket wheel (5), 2) coupling.