CN210003346U

CN210003346U - Four-stroke internal combustion engine valve mechanism and exhaust cam thereof

Info

Publication number: CN210003346U
Application number: CN201920408514.9U
Authority: CN
Inventors: 陈琳; 孟丽; 张晓�; 史美丽
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2020-01-31
Anticipated expiration: 2029-03-28

Abstract

The utility model discloses an four-stroke internal combustion engine valve actuating mechanism and exhaust cam thereof, exhaust cam's molded lines include BGR section, CR section and exhaust main lift section, BGR section end is connected with base circle section, another end through second base circle section with the CR section is connected, exhaust main lift section is connected with tie point ascending section at tie point, is connected with tie point descending section at the second tie point, the tie point ascending section with the CR section is connected, the tie point descending section with base circle section is connected, cam lift curve, cam speed curve and cam acceleration curve of tie point with second tie point are smooth continuous respectively in the valve actuating mechanism, the product of tie point descending section, BGR section, CR section negative acceleration amplitude and valve actuating mechanism equivalent mass, in the bias spring working force scope when having solved and having adopted compression release formula braking, the abnormal sound problem of valve actuating mechanism.

Description

Four-stroke internal combustion engine valve mechanism and exhaust cam thereof

Technical Field

The utility model relates to a four-stroke internal combustion engine valve actuating mechanism technical field especially relates to and sets up in the exhaust cam of valve actuating mechanism camshaft.

Background

The compression release brake system for a four-stroke internal combustion engine relies on the exhaust cam of the valve train camshaft to actively open the exhaust gases to perform the braking function, the exhaust gases are opened (commonly referred to as CR segment, CR: compression release) as the compression stroke piston approaches top dead center, the work done by the engine compressing the air in the cylinder is released into the exhaust system, the expansion stroke does not have energy to back press the piston to perform braking, in order to increase the braking power by advancing steps, the exhaust gases are opened near the end of the intake stroke (commonly referred to as BGR segment, BGR: brake gas recirculation, to increase the cylinder charge so that the engine can compress more gases and increase the braking power.

The valve train realizing the braking function generally comprises an integrated rocker arm rotatably mounted on a rocker arm shaft, an exhaust cam arranged on a cam shaft, two exhaust , an exhaust bridge, a bias spring and the like, wherein the integrated rocker arm integrates the exhaust rocker arm and the brake rocker arm into , the space arrangement is compact, the integrated rocker arm needs to be matched with a corresponding cam profile for use, the front end of the brake rocker arm is provided with a telescopic piston driven by a hydraulic control device, the piston retracts in the positive power, the brake rocker arm does not work, the piston extends out in the braking process and presses down exhaust in the braking process, at the same time, the brake rocker arm and the exhaust rocker arm work simultaneously, the rear end of the brake rocker arm is provided with a roller which abuts against the profile of the exhaust cam, the exhaust rocker arm is provided with an adjusting screw elephant foot, the adjusting screw elephant foot bridges the exhaust through the exhaust , the bias spring is mounted on the exhaust side or the exhaust cam side of the integrated rocker arm, and the BGR section and CR section are eliminated in the positive power.

The acceleration curves of the BGR section, the CR section and the main lift connecting section of the conventional compression release cam profile are not smooth and have fluctuation peaks, so that the conventional cam profile brings flexible impact to a valve mechanism, the acceleration designs of the BGR section and the CR section cam profile are unreasonable and exceed the working force range of a bias spring, the inertia force is larger along with the higher rotation speed of the cam, the elastic force of the bias spring is counteracted too much, the rocker arm cannot be pressed, the parts of the valve mechanism are contacted and separated and fly off, and the abnormal opening of the exhaust BGR section is caused when the conditions are serious, so that the abnormal sound of the valve mechanism is brought.

SUMMERY OF THE UTILITY MODEL

To prior art's above-mentioned defect, the utility model provides an kinds of four-stroke internal combustion engine valve actuating mechanism regards as with kinds of design, the utility model discloses still provide kinds of exhaust cam who sets up in engine valve actuating mechanism camshaft to when solving and adopting compression release formula braking, valve actuating mechanism's abnormal sound problem.

In order to solve the technical problems, the utility model discloses a four-stroke internal combustion engine valve train exhaust cam, the molded lines of exhaust cam include the BGR section that is used for controlling exhaust to open when the intake stroke is close to the end, the CR section that is used for controlling exhaust to open when the compression stroke piston is close to top dead center and be used for controlling exhaust to open at the exhaust stroke main lift section, BGR section 0 end is connected with base circle section and end is connected with the CR section through second base circle section, exhaust main lift section is connected with tie point ascending section at tie point, exhaust main lift section is connected with tie point descending section at second tie point, the tie point ascending section is connected with the CR section, the tie point descending section is connected with the base circle section, the cam lift curve, cam speed curve and acceleration curve of exhaust cam molded lines at tie point and second tie point are smooth continuous respectively.

The exhaust cam comprises an -th base circle segment, a BGR segment, a second base circle segment, a CR segment and a connecting point descending segment, wherein corresponding cam rotation angles of the -th base circle segment are 0-16 degrees and 354-360 degrees, corresponding cam lift ranges from 0mm, 0 degree and 360 degrees are the same positions of the exhaust cam, corresponding cam rotation angles of the BGR segment are 16-80 degrees and maximum cam lift ranges from 1.301mm, corresponding cam rotation angles of the second base circle segment are 80-86 degrees and corresponding cam lift ranges from 0.09mm, corresponding cam rotation angles of the CR segment are 86-154 degrees and maximum cam lift ranges from 1.756mm, corresponding cam rotation angles of the connecting point ascending segment are 154-182 degrees, corresponding cam rotation angles of the exhaust main lift segments are 182-325 degrees and maximum cam lift ranges from 9.614mm, and corresponding cam rotation angles of the connecting point descending segment are 325-354 degrees.

In order to solve the second technical problem, the utility model adopts the technical scheme that kinds of four-stroke internal combustion engine valve actuating mechanisms comprise an integrated rocker arm rotatably arranged on a rocker shaft, an exhaust cam arranged on a cam shaft, two exhaust , an exhaust bridge and a bias spring, wherein the integrated rocker arm comprises an exhaust rocker arm and a brake rocker arm integrated at , the front end of the brake rocker arm is provided with a piston driven by a hydraulic control device, the piston retracts in positive power, the piston extends out and presses exhaust in the exhaust cam in braking, the rear end of the brake rocker arm is provided with a roller, the roller is abutted against the molded line of the exhaust cam, the exhaust rocker arm is provided with an adjusting screw elephant foot, the adjusting screw elephant foot is bridged with the exhaust through an exhaust , the bias spring is arranged on the exhaust side of the integrated rocker arm or the exhaust cam side, and the amplitude of the mass of the connection point descending section, the BGR section, the negative acceleration of the CR section and the valve actuating mechanism equivalent mass are within the working force range of the bias spring.

Compared with the prior art, the utility model discloses an efficiency is:

1) the cam molded lines can guarantee that under the positive power condition, the BGR section and the CR section are in lift and are eliminated by a bias spring, the exhaust main lift is not influenced, the positive power is opened and the closing phase is kept unchanged, and under the braking condition, the exhaust BGR section and the CR section are opened to realize braking.

2) The exhaust cam profile is in the tie point with cam lift curve, cam speed curve and cam acceleration curve of second tie point department are smooth continuous respectively, so do not have flexible impact.

3) The tie point decline section of cam molded lines, BGR section, CR section department negative acceleration amplitude, with the product of valve train equivalent mass, control is in bias spring working force within range, consequently the cam molded lines can keep the distribution valve system good contact at the full rotational speed within range of engine, and the nothing flies to take off the separation to reduce the valve train noise.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of a valve train of four-stroke internal combustion engines according to the present invention;

FIG. 2 is a front view of the exhaust cam of FIG. 1;

FIG. 3 is a cam lift curve for the exhaust cam of FIG. 1;

FIG. 4 is a cam speed profile of the exhaust cam of FIG. 1;

FIG. 5 is a cam acceleration profile of the exhaust cam of FIG. 1;

in the figure, 1-exhaust cam, 11-main lift lobe, 12-CR lobe, 13-BGR lobe, 2-roller, 3-brake rocker, 4-exhaust rocker, 5-bias spring, 6-exhaust bridge, 7-exhaust , 8-piston, and 9-adjusting screw are shown as feet.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments, so as to further the purpose, solution and efficacy of the present invention can be understood, but not as a limitation to the scope of the appended claims.

As shown in figure 1, kinds of four-stroke internal combustion engine valve actuating mechanisms, the integrated rocker arm is rotatably mounted on the rocker shaft, the exhaust cam 1 is arranged on the camshaft, the integrated rocker arm comprises an exhaust rocker arm 4 and a brake rocker arm 3 which are integrated at , the front end of the brake rocker arm 3 is provided with a piston 8 driven by a hydraulic control device, the piston 8 retracts in positive power, the piston 8 extends out and presses down exhaust 7 in braking, the rear end of the brake rocker arm 3 is provided with a roller 2, the roller 2 abuts against the molded line of the exhaust cam 1, the exhaust rocker arm 4 is provided with an adjusting screw elephant foot 9, the adjusting screw elephant foot 9 is connected with exhaust 7 through an exhaust bridge 6, and a bias spring 5 is mounted on the exhaust side of the integrated rocker arm and also can be mounted on the exhaust cam.

Fig. 2 shows the profile of the exhaust cam 1 with a main lift lobe 11, a CR lobe 12, and a BGR lobe 13, the main lift lobe 11 corresponding to the exhaust main lift segment profile for controlling the opening of the exhaust 7 during the exhaust stroke, the CR lobe 12 corresponding to the CR segment profile for controlling the opening of the exhaust 7 near top dead center during the compression stroke piston, and the BGR lobe 13 corresponding to the BGR segment profile for controlling the opening of the exhaust 7 near the end of the intake stroke.

As shown in fig. 3 to 5, the profile of the exhaust cam 1 includes a BGR segment, a CR segment, and an exhaust main lift segment, where the BGR segment is connected to a th base circle segment and th base circle segment and the CR segment are connected to the CR segment through a second base circle segment, the exhaust main lift segment is connected to a junction point ascending segment at a th junction point, the exhaust main lift segment is connected to a junction point descending segment at a second junction point, the junction point ascending segment is connected to the CR segment, and the junction point descending segment is connected to the th base circle segment, the cam lift curves (shown in fig. 3), the cam speed curve (shown in fig. 4), and the cam acceleration curve (shown in fig. 5) of the exhaust cam profile at the th junction point (E point) and the second junction point (G point) are smooth and continuous, respectively, the cam speed curve is a derivative of a cam lift curve , and the cam acceleration curve is a second derivative of the cam lift curve.

Cam profile cam lift data see table 1: TABLE 1

With reference to table 1 and fig. 3-5, the AB and GI segments are the th base circle segment, corresponding to cam angles of 0 ° to 16 ° and 354 ° to 360 °, and corresponding to cam lift of 0mm, where 0 ° and 360 ° are the same position of the exhaust cam.

The BC segment is the BGR segment, and the corresponding cam angle is 16 ° to 80 °, with a maximum cam lift of 1.301 mm.

The CD section is the second base circle section, the corresponding cam rotation angle is 80-86 degrees, and the corresponding cam lift is 0.09 mm.

The DE section is the CR section, corresponding to a cam angle of 86 ° to 154 °, with a cam maximum lift of 1.756 mm.

The section EF is the connecting point rising section, the corresponding cam rotation angle is 154-182 °, and the point F is the th connecting point, where the cam lift curve (as shown in fig. 3), the cam speed curve (as shown in fig. 4) and the cam acceleration curve (as shown in fig. 5) are smoothly continuous respectively.

The FG section is the exhaust main lift section, and the corresponding cam rotation angle is 182-325 degrees, wherein the maximum lift of the cam is 9.614 mm.

The GI segment is the junction point descent segment, corresponding to a cam rotation angle of 325 ° to 354 °, and the G point is the second junction point where the cam lift curve (shown in fig. 3), the cam speed curve (shown in fig. 4), and the cam acceleration curve (shown in fig. 5) are smoothly continuous, respectively.

And the product of the negative acceleration amplitude and the equivalent mass of the valve train at the connection point descending section, the BGR section and the CR section of the exhaust cam molded line is within the working force range of the bias spring.

The present invention is not limited to the above embodiments, and is based on various improvements made by the concept, structure and principle of the present invention, which all fall into the protection scope of the present invention.

Claims

A valve gear exhaust cam of a four-stroke internal combustion engine of 1 and types, the molded line of the exhaust cam comprises a BGR section used for controlling the exhaust to be opened when the intake stroke is close to the end, a CR section used for controlling the exhaust to be opened when the compression stroke piston is close to the top dead center, and an exhaust main lift section used for controlling the exhaust to be opened when the exhaust stroke is close to the end, wherein the end of the BGR section is connected with a base circle section, the other end is connected with the CR section through a second base circle section, the exhaust main lift section is connected with a connecting point ascending section at a connecting point, the exhaust main lift section is connected with a connecting point descending section at a second connecting point, the connecting point ascending section is connected with the CR section, and the connecting point descending section is connected with the base circle section,

the cam lift curve, the cam speed curve and the cam acceleration curve of the exhaust cam profile at the connection point and the second connection point are respectively smooth and continuous.
2. The four-stroke internal combustion engine valve train exhaust cam of claim 1,

the th base circle segment corresponds to cam rotation angles of 0-16 degrees and 354-360 degrees and corresponds to cam lift of 0mm, wherein 0 and 360 degrees are the same positions of the exhaust cam;

the corresponding cam rotation angle of the BGR section is 16-80 degrees, wherein the maximum cam lift is 1.301 mm;

the corresponding cam rotation angle of the second base circle section is 80-86 degrees, and the corresponding cam lift is 0.09 mm;

the CR section corresponds to a cam rotation angle of 86-154 degrees, wherein the maximum lift of the cam is 1.756 mm;

the connecting point ascending section corresponds to a cam rotating angle of 154-182 degrees;

the corresponding cam rotation angle of the exhaust main lift section is 182-325 degrees, wherein the maximum lift of the cam is 9.614 mm;

the connecting point descending section corresponds to a cam rotation angle of 325-354 degrees.
The valve train of the four-stroke internal combustion engine of kind, including:

the integrated rocker arm is rotatably arranged on a rocker arm shaft, an exhaust cam arranged on a cam shaft, two exhaust , an exhaust bridge and a bias spring, wherein the integrated rocker arm comprises the exhaust rocker arm and a brake rocker arm which are integrated on , the front end of the brake rocker arm is provided with a piston driven by a hydraulic control device, the piston retracts in positive power, the piston extends out and presses down exhaust in braking, the rear end of the brake rocker arm is provided with a roller which is abutted against the molded line of the exhaust cam, the exhaust rocker arm is provided with an adjusting screw elephant foot which is bridged with the exhaust through the exhaust , and the bias spring is arranged on the exhaust side or the exhaust cam side of the integrated rocker arm,

the exhaust cam is the exhaust cam according to claim 1 or 2, and the product of the negative acceleration amplitude and the valve train equivalent mass at the connecting point descending section, the BGR section and the CR section of the exhaust cam profile is within the working force range of the bias spring.