CN210178471U

CN210178471U - Engine compression ratio adjusting mechanism

Info

Publication number: CN210178471U
Application number: CN201920486020.2U
Authority: CN
Inventors: 林松; 王瀚超; 何军; 李理光; 王金秋; 晁岳栋; 王硕
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2019-04-11
Filing date: 2019-04-11
Publication date: 2020-03-24
Anticipated expiration: 2029-04-11

Abstract

The utility model discloses an engine compression ratio adjusting mechanism, which comprises a crank connecting rod component and a compression ratio adjusting component, wherein the crank connecting rod component comprises a piston, a connecting rod and a crank; the driving gear is coaxially and fixedly connected with the crank, a driven gear meshed with the driving gear is arranged on the side of the driving gear, the driven gear is coaxially and fixedly connected with an output shaft, and the output shaft is fixed on a cylinder body of the engine; the compression ratio adjusting component comprises a plurality of adjusting connecting rods connected with the crank; one end of the adjusting connecting rod is provided with an adjusting sliding pin, one end of the adjusting sliding pin is fixedly connected with the adjusting connecting rod, and the other end of the adjusting sliding pin is positioned in the sliding groove; the other end of the adjusting connecting rod is connected with the height adjusting unit, and the height adjusting unit changes the positions of the crank connecting rod assembly and the driving gear through the adjusting connecting rod to realize the adjustment of the compression ratio.

Description

Engine compression ratio adjusting mechanism

Technical Field

The utility model relates to an internal-combustion engine field, specifically speaking, in particular to engine compression ratio adjustment mechanism.

Background

The working process of the ignition engine is similar to the Otto cycle, and the proper improvement of the compression ratio is beneficial to improving the thermal efficiency of the engine under the working condition of small load, thereby reducing the oil consumption. However, the compression ratio cannot be increased infinitely. An excessively high compression ratio can cause the engine to knock or even super knock under a low-speed and high-load working condition, so that the smoothness of the engine is influenced, and even the engine is damaged.

Existing mass-produced engines typically use a fixed compression ratio. In order to make the engine work normally under different loads, the compression ratio is usually not high, and is generally between 8 and 12. In order to meet the different requirements of the engine on the compression ratio under different loads, exert the maximum potential of the engine, reduce oil consumption and pollutant emission, the variable compression ratio engine is necessary to be used.

Because the technology is immature, the cost is high and the like, the variable compression ratio engine is not put into production in large quantity, and the variable compression ratio engine sold in the market is only one VC-Turbo engine of Eneffinella. The engine of the model adopts a multi-connecting rod mode to realize the adjustment of the compression ratio, and the Chinese patent application number of the product is CN 201380070791.9. However, the way of adjusting the compression ratio of the engine by the multi-link has major defects, such as: the additional increase of the mechanism results in more weight gain, the increase of the friction loss caused by the increase of the movable parts, the difficulty in ensuring the dynamic balance and the like.

In addition to multi-link adjustment, the engine compression ratio is adjusted by changing the cylinder head height (CN201310076251.3), changing the link length (CN 201580025307.X), changing the crankshaft position (CN201710473417.3), changing the piston height (CN 201410474676.4), adding a second piston (CN201310624860.8), and the like. Although the methods can be obtained by modifying the existing fixed compression ratio engine, the problems of extra increase, more extra friction loss increase, short service life, poor compression ratio control precision, difficulty in stepless adjustment and the like exist.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an engine compression ratio adjustment mechanism to the not enough among the prior art to solve the problem that exists among the prior art.

The utility model provides a technical problem can adopt following technical scheme to realize:

an engine compression ratio adjusting mechanism comprises a crank connecting rod assembly, wherein the crank connecting rod assembly comprises a piston, a connecting rod and a crank; the driving gear is coaxially and fixedly connected with the crank, a driven gear meshed with the driving gear is arranged on the side of the driving gear, the driven gear is coaxially and fixedly connected with an output shaft, and the output shaft is fixed on a cylinder body of the engine;

the compression ratio adjusting assembly comprises a plurality of adjusting connecting rods connected with the crank; one end of the adjusting connecting rod is provided with an adjusting sliding pin, one end of the adjusting sliding pin is fixedly connected with the adjusting connecting rod, and the other end of the adjusting sliding pin is positioned in the sliding groove; the other end of the adjusting connecting rod is connected with the height adjusting unit, and the height adjusting unit changes the positions of the crank connecting rod assembly and the driving gear through the adjusting connecting rod to realize the adjustment of the compression ratio.

Furthermore, the height adjusting unit comprises a nut, the nut is sleeved on the screw rod and can move up and down along the screw rod, and the side face of the nut is connected with the other end of the adjusting connecting rod through a hinge.

Furthermore, the nut, the sliding pin and the adjusting connecting rod form a double-slider mechanism, the axis of the crank is positioned at the midpoint of a connecting line of the center of the hinge and the axis of the adjusting sliding pin, and the axis of the output shaft is positioned at the intersection point of the perpendicular line of the center of the hinge and the transverse center line of the sliding chute.

Furthermore, the moving track of the crank is a circular track, and an offset distance of 1-3cm is formed between the circular track and the axis of the cylinder.

Furthermore, the two circle center positions of the driven gear under the two limit compression ratios are symmetrical along a horizontal line passing through the center of the driving gear.

Furthermore, the driven gear and the output shaft, and the driving gear and the crank are connected through splines.

Furthermore, lightening holes are formed in the driven gear and the driving gear.

Furthermore, when the compression ratio of the engine is adjusted, the crank is driven by the adjusting connecting rod, and meanwhile, the connecting rod, the piston and the driving gear move along with the crank; when the crank moves from top to bottom according to a circular track, the compression ratio of the engine is changed from high to low.

Furthermore, when the engine runs, the crank drives the driving gear fixedly connected with the crank to rotate through rotation, the driving gear transmits power to the driven gear meshed with the driving gear, and the driven gear transmits the power to the output shaft.

Further, the gear ratio of the driven gear to the driving gear is 1: 1.

compared with the prior art, the beneficial effects of the utility model reside in that:

1. the engine compression ratio can be steplessly adjusted in a wider range according to working conditions, the detonation probability of the engine under a large load is reduced, and the fuel economy under medium and small loads is improved, so that the oil consumption is reduced, and the pollutant emission is reduced.

2. The engine works normally in a steady state, namely, when the compression ratio is not changed, the friction pairs are not increased, and the friction loss is smaller; the adjusting mechanism is simple, and the increased cost is less;

3. because of using the gear drive mode, transmission efficiency is high, and the durability is good, and the operation is reliable.

Drawings

Fig. 1 is a schematic diagram of an engine compression ratio adjusting mechanism according to the present invention.

Fig. 2 is an exploded view of the compression ratio adjusting mechanism of the engine of the present invention.

Fig. 3 is a right side view of the internal combustion engine at compression top dead center timing in a compression ratio maximum state.

Fig. 4 is a right side view of the internal combustion engine at compression top dead center time in a compression ratio minimum state.

Detailed Description

In order to make the technical means, creation features, achievement purposes and functions of the present invention easy to understand, the present invention is further described below with reference to the following embodiments.

Referring to fig. 1 and 2, the engine compression ratio adjusting mechanism of the present invention includes a driven gear 5, a driving gear 3, a lead screw 8, a nut 7, a sliding chute 10, an adjusting link 11, a hinge 12, an adjusting sliding pin 9, a sliding chute 10, and an output shaft 6.

Wherein, the nut 7, the screw 8, the adjusting sliding pin 9, the sliding chute 10, the adjusting connecting rod 11 and the hinge 12 form a compression ratio adjusting device, and the five sets are arranged on the shaft neck of the crank 4. When the engine adjusts the compression ratio, the five sets of devices are completely and synchronously adjusted.

The nut 7 and the adjusting sliding pin 9 are respectively arranged at two sides of the adjusting connecting rod 11, the nut and the adjusting sliding pin form a double-slider mechanism together with the sliding chute 10 and the screw rod 8, and the sliding pin 9 can slide in the sliding chute 10; the height of the nut 7 is changed by rotating the screw rod 8, and the adjusting connecting rod 11 is driven to move by the hinge 12; the motion trail of the central point of the connecting rod 11 is circular; the crank 4 is mounted at the midpoint of the adjusting link 11 using a bearing bush, and is movable as the adjusting link 11 moves.

The driven gear 5 is fixedly connected with the crank 4 through a spline and is meshed with the driving gear 3; the driving gear 3 is connected with an output shaft 6 through a spline; the number of teeth of the two gears is the same, so that the rotating speed of the output shaft 6 of the engine is ensured to be the same as that of the crank 4; the output shaft 6 is arranged on the cylinder body by using a bearing, the other end of the output shaft extends out of the engine and is connected with the flywheel by using a spline; the middle point of the connecting line of the hinge 12 and the axis of the adjusting sliding pin 9 is positioned on the axis of the crank 4, so that the radius of the axis motion track circle of the crank 4 is equal to the distance between the driven gear 5 and the axis of the driving gear 3, and the driven gear 5 can be normally meshed with the driving gear 3 when moving to any position along with the crank 4.

When the engine normally works, namely the compression ratio is not adjusted, the piston 1 and the connecting rod 2 drive the crank 4 to normally rotate, the crank 4 drives the driving gear 3 fixedly connected with the crank 4 to rotate, and then the driven gear 5 rotates; the spatial position of the driven gear 5 is unchanged.

Referring to fig. 3, when the compression ratio of the engine needs to be raised, the screw 8 is rotated to move the nut 7 upwards, so as to drive the crank 4 and the driving gear 3 to move upwards, so that the top dead center position of the piston 1 is moved upwards, and the compression ratio of the engine is raised; the motion track of the driving gear 3 ensures that the power transmission is carried out uninterruptedly in the moving process;

referring to fig. 4, when the compression ratio of the engine needs to be lowered, the screw 8 is rotated to move the nut 7 downwards, so as to drive the crank 4 to move downwards; the top dead center position of the piston 1 is moved downward and the engine compression ratio is accordingly lowered.

Referring to fig. 3 and 4, under the compression ratio of two extreme positions of the engine, the two extreme positions of the circle center of the driven gear 5 are symmetrical along a horizontal line passing through the driving gear 3, so that the piston stroke is basically unchanged while the top dead center position of the piston is changed.

The basic principles and the main features of the invention and the advantages of the invention have been shown and described above. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. An engine compression ratio adjusting mechanism comprises a crank connecting rod assembly, wherein the crank connecting rod assembly comprises a piston (1), a connecting rod (2) and a crank (4); the driving gear (3) is coaxially and fixedly connected with the crank (4), a driven gear (5) meshed with the driving gear is arranged on the side of the driving gear (3), the driven gear (5) is coaxially and fixedly connected with an output shaft (6), and the output shaft (6) is fixed on a cylinder body of an engine;

the method is characterized in that: the compression ratio adjusting assembly comprises a plurality of adjusting connecting rods (11) connected with the crank (4); one end of the adjusting connecting rod (11) is provided with an adjusting sliding pin (9), one end of the adjusting sliding pin (9) is fixedly connected with the adjusting connecting rod (11), and the other end of the adjusting sliding pin (9) is positioned in the sliding groove (10); the other end of the adjusting connecting rod (11) is connected with a height adjusting unit, and the height adjusting unit changes the positions of the crank connecting rod assembly and the driving gear (3) through the adjusting connecting rod (11) to realize the adjustment of the compression ratio.

2. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: the height adjusting unit comprises a nut (7), the nut (7) is sleeved on the lead screw (8) and can move up and down along the lead screw (8), and the side face of the nut (7) is connected with the other end of the adjusting connecting rod (11) through a hinge (12).

3. The engine compression ratio adjustment mechanism according to claim 2, characterized in that: the nut (7), the sliding pin (9) and the adjusting connecting rod (11) form a double-slider mechanism, the axis of the crank (4) is positioned on the midpoint of the connecting line of the center of the hinge (12) and the axis of the adjusting sliding pin (9), and the axis of the output shaft (6) is positioned on the intersection point of the perpendicular line of the center of the hinge (12) and the transverse center line of the sliding chute (10).

4. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: the moving track of the crank (4) is a circular track, and an offset distance of 1-3cm is formed between the circular track and the axis of the cylinder.

5. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: the two circle center positions of the driven gear (5) under the two limit compression ratios are symmetrical along a horizontal line passing through the center of the driving gear (3).

6. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: the driven gear (5) is connected with the output shaft (6), the driving gear (3) and the crank (4) through splines.

7. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: lightening holes are formed in the driven gear (5) and the driving gear (3).

8. The engine compression ratio adjustment mechanism according to claim 4, characterized in that: when the compression ratio of the engine is adjusted, the crank (4) is driven by the adjusting connecting rod (11), and meanwhile, the connecting rod (2), the piston (1) and the driving gear (3) move along with the crank (4); when the crank (4) moves from top to bottom according to a circular track, the compression ratio of the engine is changed from high to low.

9. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: when the engine runs, the crank (4) drives the driving gear (3) fixedly connected with the crank to rotate through rotation, the driving gear (3) transmits power to the driven gear (5) meshed with the driving gear, and the driven gear (5) transmits the power to the output shaft (6).

10. The engine compression ratio adjustment mechanism according to claim 1, characterized in that: the gear ratio of the driven gear (5) to the driving gear (3) is 1: 1.