CN102486104A

CN102486104A - Exhaust cam of small gasoline engine

Info

Publication number: CN102486104A
Application number: CN2010106208630A
Authority: CN
Inventors: 韦家良; 陈磊; 唐海娇
Original assignee: SAIC GM Wuling Automobile Co Ltd
Current assignee: SAIC GM Wuling Automobile Co Ltd
Priority date: 2010-12-31
Filing date: 2010-12-31
Publication date: 2012-06-06
Anticipated expiration: 2030-12-31
Also published as: CN102486104B

Abstract

The invention provides an exhaust cam of a small gasoline engine. The design range of radius of a base circle in molded lines is 16-18mm to ensure that the molded lines of the cam can be in smooth transition. In practical engine durability tests, the design requirements of the engine are fully satisfied. The design range of the maximum lift of the cam is 7-8mm. The design range of lift of a buffer section of the cam is 0.2-0.4mm. Both of the high-speed performance and the low-speed performance of the engine can be considered. Therefore, optimization of performance at different rotating speeds can be realized. The maximum acceleration of the exhaust cam reaches 72.2mm/rad2, the fly-off speed of the exhaust cam reaches 6900rpm and is larger than the maximum rotating speed of the engine, i.e. 6000rpm, the situation that the cam flies off is eliminated and the situation of abnormal wearing on one tappet of the cam in practical use is avoided. Therefore, the engine realizes the effects of high power per liter, high compression ratio, low oil consumption, low speed high-torque and the like, and the performance of the entire engine is greatly improved.

Description

A kind of exhaust cam of put-put

[technical field]

The present invention relates to the engine design field, relate in particular to a kind of exhaust cam of put-put.

[background technique]

The design of cam profile plays tremendous influence to the performance of motor.The design cam profile promptly is a cam curve reasonable in design, and the switching of controlling valve is to cooperate bent axle-piston motion air inlet or exhaust, and good cam profile can make full use of air inlet inertia, improve charging efficiency, thereby improves the performance of motor.Bad cam profile design can cause the motor charging efficiency low, and power, moment of torsion are low, insufficient lubrication between cam-tappet, part inordinate wear, severe patient even can cause distribution device to occur flying off and the air valve drop rebound phenomenon.

Reasonable optimizing is not carried out in the cam profile design of using on the existing put-put; HP, hp/litre is low, oil consumption is high, compression ratio is little, performance is not good; And cam profile all adopts the design of opening section and the section of closing symmetric type, can't take into account the requirement of motor for the slow-speed of revolution and high rotating speed different performance.

[summary of the invention]

Problems such as the HP, hp/litre that causes is low, oil consumption is high, compression ratio is little in order to solve not enough optimization of cam profile design of using on the middle-size and small-size petrol engine of existing technology; The invention provides a kind of exhaust cam of put-put, this cam has the molded lines design of more optimizing.

The exhaust cam of the put-put among the present invention; The molded lines of this cam comprises basic circle and cam peach; The radial center of the center of circle of basic circle and cam peach coincides with cam center; And two end points of basic circle overlap with two end points of cam peach respectively, and two end points of cam peach are respectively to open end points and close end points; Also comprise the breeze way starting point on the cam peach, eliminate valve clearance point, valve maximum lift point, valve-closing point and close the breeze way end point fully; The radius of basic circle is 16～18mm; The cam maximum lift is 7～8mm; Cam breeze way lift is 0.2～0.4mm.

Of the present inventionly further be improved to: the radius of basic circle is 17mm; The beginning angle of opening between end points to the breeze way starting point is 7 °; Breeze way starting point to the unlatching breeze way angle of eliminating between the point of valve clearance fully is 25.5 °; The valve opening section angle of eliminating fully between valve clearance point to the valve maximum lift point is 57.5 °; Closing flank angle between valve maximum lift point to the valve-closing point is 57.5 °; Valve-closing point to the breeze way angle of closing of closing between the breeze way end point is 25.5 °; Closing buffering end point to the angle at the end of closing between the end points is 7 °; The valve maximum lift point is 24.55mm to the distance of cam center; The cam maximum lift is 7.55mm; Cam breeze way lift is 0.32mm.

In existing technology, the exhaust cam of the put-put in the invention, the Base radius scope of design in the molded lines of this cam is 16～18mm; Make that cam profile can smooth transition; In the Engine Durability test of reality, reached the designing requirement of motor fully, when the design load of Base radius exceeds 16～18mm scope; The wear extent of cam changeover portion is between 50 μ m～60 μ m, and the wear extent of Base radius cam changeover portion when being chosen in 16～18mm scope is less than 50 μ m; The maximum lift scope of design of cam profile is 7～8mm; Breeze way cam lift scope of design is 0.2～0.4mm, can take into account the high, low speed performance of motor, thereby can realize optimization in Properties under the motor different rotating speeds.Exhaust cam among the present invention has been realized maximum acceleration 72.2mm/rad ²It flies off speed and has reached 6900rpm; Greater than engine peak speed 6000rpm, eliminated cam and flown off phenomenon, and cam-tappet does not have the inordinate wear phenomenon in actual use; Thereby motor realized effects such as high power per liter, high compression ratio, low oil consumption, the high moment of torsion of the slow-speed of revolution, improved machine performance greatly.

[description of drawings]

Fig. 1 is the molded lines schematic representation of the exhaust cam of put-put of the present invention.

[embodiment]

Below in conjunction with description of drawings and embodiment the present invention is further specified.

As shown in Figure 1; The exhaust cam of the put-put among the present invention; Its molded lines comprises basic circle 1 and cam peach 2; The radial center of the center of circle of basic circle 1 and cam peach 2 coincides with cam center 14, and two end points of basic circle 1 overlap with two end points of cam peach 2 respectively, and two end points of cam peach are respectively to open end points 2a and close end points 2b; Also comprise breeze way starting point 4 on the cam peach 2, eliminate valve clearance point 6 (being the breeze way end point), valve maximum lift point 8, valve-closing point 10 and close breeze way end point 12 fully; The radius of basic circle 1 is 16～18mm; The cam maximum lift is 7～8mm; Cam breeze way lift is 0.1～0.3mm.

The radial design of basic circle 1 is 16～18mm among the present invention, selects scope 15～17mm with respect to the Base radius in the tradition, more helps guaranteeing the smooth transition of cam profile, more helps cam structure optimization; It is 7～8mm that the maximum lift of cam profile is designed to; The breeze way cam lift is designed to 0.2～0.4mm, can take into account the high, low speed performance of motor, thereby can realize optimization in Properties under the motor different rotating speeds.

The preferred scheme of the present invention is: the radius of basic circle is 17mm, and 17mm is the optimal values that realizes the smooth transition of this cam profile, and in the Engine Durability test, the wear extent of cam changeover portion has reached the designing requirement of motor fully less than 50 μ m; The beginning angle of opening between end points to the breeze way starting point is 7 °; Breeze way starting point to the unlatching breeze way angle of eliminating between the point of valve clearance fully is 25.5 °; The valve opening section angle of eliminating fully between valve clearance point to the valve maximum lift point is 57.5 °; Closing flank angle between valve maximum lift point to valve-closing point is 57.5 °; Valve-closing point to the breeze way angle of closing of closing between the breeze way end point is 25.5 °; Closing buffering end point to the angle at the end of closing between the end points is 7 °; The valve maximum lift point is 24.55mm to the distance of cam center; The maximum lift of cam profile is 7.55mm; The breeze way cam lift is 0.32mm.Exhaust cam has been realized maximum acceleration 72.2mm/rad ², and its fly off speed and reached 6900rpm, greater than engine peak speed 6000rpm, fly off phenomenon thereby eliminated; Cam-tappet does not have the inordinate wear phenomenon in actual use; Thereby motor realized effects such as high power per liter, high compression ratio, low oil consumption, the high moment of torsion of the slow-speed of revolution, improved machine performance greatly.It mainly is to reduce the motor residual gas that the parameter of exhaust cam is selected, and improves engine power.

Above content is to combine concrete preferred implementation to the further explain that the present invention did, and can not assert that practical implementation of the present invention is confined to these explanations.For the those of ordinary skill of technical field under the present invention, under the prerequisite that does not break away from the present invention's design, can also make some simple deduction or replace, all should be regarded as belonging to protection scope of the present invention.

Claims

1. the exhaust cam of a put-put; The molded lines of this cam comprises basic circle (1) and cam peach (2); The radial center of the center of circle of said basic circle (1) and said cam peach (2) coincides with cam center (14); And two end points of said basic circle overlap with two end points of said cam peach respectively, and two end points of said cam peach are respectively to open end points (2a) and close end points (2b); Also comprise breeze way starting point (4) on the said cam peach (2), eliminate valve clearance point (6), valve maximum lift point (8), valve-closing point (10) and close breeze way end point (12) fully; It is characterized in that: the radius of said basic circle (1) is 16～18mm; The cam maximum lift is 7～8mm; Cam breeze way lift is 0.2～0.4mm.

2. the exhaust cam of put-put according to claim 1, it is characterized in that: the radius of said basic circle (1) is 17mm; Beginning angle (3) between said unlatching end points (2a) to the said breeze way starting point (4) is 7 °; Said breeze way starting point (4) to the said unlatching breeze way angle of eliminating fully between the valve clearance point (6) (5) is 25.5 °; The said valve opening section angle of eliminating fully between valve clearance point (6) to the said valve maximum lift point (8) (7) is 57.5 °; Closing flank angle (9) between said valve maximum lift point (8) to the said valve-closing point (10) is 57.5 °; Said valve-closing point (10) to the said breeze way angle (11) of closing of closing between the breeze way end point (12) is 25.5 °; Said close the buffering end point (12) to said angle at the end (13) of closing between the end points (2b) be 7 °; Said valve maximum lift point (8) is 24.55mm to the distance of said cam center (14); Said cam maximum lift is 7.55mm; Said cam breeze way lift is 0.32mm.