CN212154896U

CN212154896U - Variable lift valve structure

Info

Publication number: CN212154896U
Application number: CN202020746415.4U
Authority: CN
Inventors: 邓文高
Original assignee: Guangxi Yuchai Machinery Co Ltd
Current assignee: Guangxi Yuchai Machinery Co Ltd
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2020-12-15
Anticipated expiration: 2030-05-08

Abstract

The utility model discloses a variable lift valve structure. It includes: a hydraulic control device; a rocker mechanism comprising a coaxial clearance fit: rocker arms and rocker arm shafts; a rocker arm lift mechanism comprising: the hydraulic cylinder is fixedly connected to the cylinder cover, the piston divides the hydraulic cylinder into two chambers, and the two chambers are respectively connected with the hydraulic control device through hydraulic pipelines; one end of the piston rod is connected with the piston, and the other end of the piston rod is circumferentially limited and extends out of the hydraulic cylinder to be connected with the rocker shaft; and a variable cross-section cam mechanism including: the cam surface profile of the variable cross-section cam is continuously, smoothly and variably, and a first cavity and a second cavity which are connected are arranged in the variable cross-section cam; the camshaft passes through the middle of the first chamber and the second chamber to isolate the first chamber from the second chamber. The variable lift valve structure overcomes the defects of more increasing mechanisms and large friction loss power of the variable valve lift system in the prior art.

Description

Variable lift valve structure

Technical Field

The utility model relates to an engine field especially relates to a variable lift valve structure.

Background

The air distribution mechanism of the engine is responsible for providing fresh air necessary for fuel combustion to work for the cylinder and discharging combusted waste gas. The main function is to open and close the intake and exhaust valves of each cylinder according to a certain time limit, thereby realizing the whole process of air change supply of the engine cylinder. The larger the angle at which the valve is opened, the longer the opening time, the greater the amount of in-and-out airflow, and vice versa. This creates the concept of valve lift and timing,

in order to further develop the potential of the traditional internal combustion engine, engineers develop a variable valve lift technology on the basis of the variable valve timing technology, and when the variable valve timing technology and the variable valve lift technology are effectively combined, higher air intake and exhaust efficiency is provided for the engine under various working conditions and rotating speeds. The oil consumption level is also reduced while the power is improved.

At present, methods for realizing variable valve lift have the following typical modes at home and abroad:

1. honda i-VTEC technique.

The structure and the working principle of the Honda variable valve lift system are that the third rocker arm and the third cam are used for realizing the valve lift change. When the engine is in a middle and low rotating speed, the three rocker arms are in a separated state, the common cam pushes the main rocker arm and the auxiliary rocker arm to control the opening and closing of the two inlet valves, and the valve lift is small. At this time, although the middle cam also pushes the middle rocker arm, the rocker arms on the two sides are not controlled by the middle cam because the rocker arms are separated, and the opening and closing states of the valve are not influenced. When the engine reaches a certain set rotating speed, the computer can instruct the electromagnetic valve to start the hydraulic system to push the small piston in the rocker arm, so that the three rocker arms are locked into a whole and driven by the high-angle cam, and at the moment, the lift range and the opening time of the valve are correspondingly increased, so that the air inflow in unit time is larger, and the engine power is stronger.

The i-VTEC technique of Honda has the defects that: the valve lift system cannot be continuously adjusted and is a two-section type variable valve lift system.

2. Valvetonic technology by BMW.

The BMW Valvetonic system adds an eccentric shaft, a stepping motor, an intermediate push rod and other components on the traditional valve timing mechanism, and skillfully changes the size of the lift of an intake valve after a series of mechanical transmission by the rotation of the stepping motor. When the camshaft runs, the cam drives the intermediate push rod and the rocker arm to complete the opening and closing of the valve. When the motor works, the worm gear mechanism can firstly drive the eccentric shaft to rotate, then the middle push rod and the rocker arm can be linked, the rotating angles of the eccentric shaft are different, and finally the lift range generated when the camshaft pushes the valve through the middle push rod and the rocker arm is also different.

The valvetonic technology of bmw has the following defects: is a continuously adjustable variable valve lift system, but the added mechanism takes up more space.

3. Day-old VVEL technology.

The VVEL system of infliximandi works on a similar principle to the valvetonic system of BMW, but is slightly different in structure. The VVEL system realizes continuous adjustment of the valve lift by using a set of combination of a threaded sleeve and a screw. When the system works, the relative position of the screw rod and the threaded sleeve is controlled by the motor through an ECU signal, and the threaded sleeve drives the rocker arm, the control rod and other components to finally change the valve lift. The rocker arm is sleeved on the control rod through the eccentric wheel, and the control rod can rotate for a certain angle under the driving of the motor. When the engine is in high rotating speed or large load, the motor drives the screw rod to rotate, the threaded sleeve sleeved on the screw rod can also generate corresponding transverse movement, and the control rod rotates anticlockwise or clockwise through the mechanism linked with the threaded sleeve. The rocker arm is sleeved on the eccentric wheel of the control rod, so that the rotating center of the rocker arm can rise or fall along with the rocker arm, and the purpose of changing the valve lift is achieved.

Daily VVAL is a continuously adjustable variable valve lift system, but the added mechanism occupies larger space and the friction pair has more power loss.

4. Domestic utility model patent (CN 105909332A) electrodeless variable lift valve rocker mechanism and corresponding valve device

The utility model discloses a connect traditional valve train's rocking arm strong point on crank link mechanism, utilize crank link mechanism's dead point as the hinge point of lever, its crank is an eccentric wheel, and the connecting rod is an eccentric ways outside the eccentric wheel, and its crank axle center biasing is on the turbine, drives the turbine rotation with the worm, realizes the electrodeless change of crank axle center position.

When the cam rotates, the elastic force of the valve spring is greater than that of the connecting rod return spring at the beginning, the rocker arm swings with the hinged point of the rocker arm and the valve rod as a fulcrum, the middle fulcrum moves along with the rocker arm and drives the crank connecting rod to move until the connecting rod and the crank form a straight line and reach a dead point position, and the distance from the middle fulcrum of the rocker arm to the axis of the crank cannot be increased. Then the valve rocker is pushed to open the valve by taking the middle fulcrum of the rocker as a support and the residual height of the cam. It can be seen that the magnitude of the valve opening will be less than the design level of the cam. When the cam rotates over an extreme point of elevation, the elevation is continuously reduced, and the valve rod is gradually rebounded under the action of the valve rod spring to drive the valve rocker to reversely swing. At the moment, the power of the swing of the valve rocker arm is converted into a valve rod spring by a cam, and the fulcrum is converted to the cam. The force on the intermediate fulcrum no longer points in the direction of extension of the crank link and the link return spring 64 begins to pull the crank link out of the dead center position. As the elevation of the cam continues to decrease until it returns to zero, both the rocker arm and the crank link return to their initial positions. The utility model discloses a patent (CN 105909332A) electrodeless variable lift valve rocker mechanism and corresponding valve gear is continuous adjustable variable valve lift system, but the crank connecting rod friction is vice more power loss.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information constitutes prior art already known to a person skilled in the art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a variable lift valve structure that simple structure is reasonable, it has overcome the variable valve lift system of prior art and has increased the not enough that the mechanism is many, friction loss power is big.

In order to achieve the above object, the present invention provides a variable lift valve structure, including: a hydraulic control device; a rocker mechanism comprising a coaxial clearance fit: rocker arms and rocker arm shafts; a rocker arm lift mechanism comprising: the hydraulic cylinder is fixedly connected to the cylinder cover, the piston divides the hydraulic cylinder into two chambers, and the two chambers are respectively connected with the hydraulic control device through hydraulic pipelines; one end of the piston rod is connected with the piston, and the other end of the piston rod is circumferentially limited and extends out of the hydraulic cylinder to be connected with the rocker shaft; and a variable cross-section cam mechanism including: the cam surface profile of the variable cross-section cam is continuously, smoothly and variably, and a first cavity and a second cavity which are connected are arranged in the variable cross-section cam; the camshaft passes through the middle of the first chamber and the second chamber to isolate the first chamber and the second chamber; the two ends of the cam shaft are respectively provided with a first oil duct and a second oil duct, one ends of the first oil duct and the second oil duct are connected with a hydraulic control device, a first oil duct opening at the other end of the first oil duct is located in the first cavity, and a second oil duct opening at the other end of the second oil duct is located in the second cavity.

In a preferred embodiment, the rocker shaft is disposed through the other end of the piston rod.

In a preferred embodiment, the rocker shaft is an interference fit with the piston rod.

In a preferred embodiment, a sealing ring is arranged between the cam shaft and the variable cross-section cam.

In a preferred embodiment, the cam shaft is keyed to the variable-section cam so that the variable-section cam can move in the axial direction of the cam shaft.

In a preferred embodiment, two retainer rings are mounted on the camshaft, one on each side of the variable-section cam.

Compared with the prior art, according to the utility model discloses a variable lift valve structure has following beneficial effect: the variable lift valve structure overcomes the defects of more increasing mechanisms and large friction loss power of the variable valve lift system in the prior art. The hydraulic oil distribution mechanism has the advantages of small change on the traditional valve mechanism, few added mechanical parts and friction pairs, almost no additional friction work increase, and the hydraulic oil has a lubricating effect. Furthermore, the section change of the cam is reasonably designed, so that the opening phase of the valve can be changed, and the variable lift and variable valve timing can be realized simultaneously.

Drawings

Fig. 1 is a schematic front view of a variable lift valve structure according to an embodiment of the present invention.

Fig. 2 is a schematic top view of a variable lift valve structure according to an embodiment of the present invention.

Fig. 3 is a schematic structural view of a variable cross-section cam mechanism of a variable lift valve structure according to an embodiment of the present invention.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited by the following detailed description.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

As shown in fig. 1 and 2, a specific structure of a variable lift valve structure according to a preferred embodiment of the present invention includes: a rocker arm mechanism, a rocker arm lifting mechanism, a variable cross-section cam mechanism and a hydraulic control device 25. The variable-section cam mechanism and the rocker arm lifting mechanism are in control connection with the hydraulic control device 25, and the rocker arm lifting mechanism controls the rocker arm mechanism to lift and is in contact with a variable-section cam of the variable-section cam mechanism, so that the defects that the variable valve lift system in the prior art is large in mechanism increase and large in friction loss power are overcome. Furthermore, the section change of the variable-section cam is reasonably designed, so that the opening phase of the valve can be changed, and the variable lift and variable valve timing can be realized simultaneously.

Specifically, the rocker mechanism includes: rocker arm 3 and rocking arm axle 4, rocking arm axle 4 and rocking arm 3 coaxial clearance fit.

The rocker arm lifting mechanism comprises: the hydraulic cylinder 8 is fixedly connected to a cylinder cover 9, the piston 7 divides the hydraulic cylinder 8 into two chambers, and the two chambers are respectively connected with a hydraulic control device 25 through hydraulic pipelines. One end of the piston rod 5 is connected with the piston 7, and the other end of the piston rod is circumferentially limited and extends out of the hydraulic cylinder 8 to be connected with the rocker shaft 4 (the piston rod 5 is in a non-circular section, the hydraulic cylinder 8 is provided with a hole which is opposite to the cross section of the piston rod 5, and the piston rod 5 extends out of the hole to be circumferentially limited, so that the piston rod 5 can only slide along the rod axis direction relative to the hydraulic cylinder 8 and can not rotate around the rod axis, and the rocker 3 can swing in one plane).

In one embodiment, the rocker shaft 4 is disposed through the other end of the piston rod 5.

In one embodiment, the rocker shaft 4 is an interference fit with the piston rod 5.

As shown in fig. 3, the variable cross-section cam mechanism includes: a variable cross-section cam 1 and a camshaft 2. The cam surface profile of the variable cross-section cam 1 is continuously, smoothly and variably, a first chamber 12 and a second chamber 13 which are connected are arranged in the variable cross-section cam 1, and the cam shaft 2 penetrates through the first chamber 12 and the second chamber 13 to be isolated. First oil duct 21 and second oil duct 24 have been seted up respectively to camshaft 2 both ends, and the one end of the two all is connected with hydraulic control device 25, and first oil duct 21 the other end first oil duct port 22 is located first cavity 12, and the second oil duct port 23 of the 24 other ends of second oil duct is located second cavity 13, and the oil duct port of two oil ducts is slightly less than the size of the single chamber of variable cross section cam 1 along camshaft 2 axis directions along the distance of camshaft 2 axis directions.

In one embodiment, a seal ring 11 is disposed between the camshaft 2 and the variable-section cam 1.

In one embodiment, the cam shaft 2 is matched with the variable-section cam 1 through a key, so that the variable-section cam 1 can move along the axial direction of the cam shaft 2.

In one embodiment, two retainer rings 10 are mounted on the camshaft 2, one on each side of the variable-section cam 1, at 2 maximum displacements of the variable-section cam 1 that are allowed to move. The inner ring of the retainer ring 10 is in transition fit with a corresponding groove on the camshaft 2 so as to prevent the variable-section cam 1 from moving too much and not moving backwards.

As shown in figure 1, high pressure oil is introduced below a piston 7 of a hydraulic cylinder 8 through a hydraulic control device 25 to push the piston 7 to move upwards, a rocker arm shaft 4 and a rocker arm 3 are driven by a piston rod 5 to move upwards, the piston rod 5 is of a non-circular section, a hole with a shape opposite to that of the section of the piston rod 5 is arranged on the top surface of the hydraulic cylinder 8, the piston rod 5 extends out of the hole, can only slide along the rod axis direction relative to the hydraulic cylinder 8 and cannot rotate around the rod axis, and therefore the rocker arm 3 can be guaranteed to swing in one plane. Meanwhile, high-pressure oil is introduced into a first oil duct 21 in the camshaft 2 through a hydraulic control device 25, the high-pressure oil enters a first chamber 12 in the variable-section cam 1 through a first oil duct 22 on the camshaft 2 and returns oil through a second chamber 13 and a second oil duct 24 to push the variable-section cam 1 to move along the axial direction of the camshaft 2, one end of the rocker arm 3 is made to be in contact with the variable-section cam 1, then the hydraulic control device 25 keeps the hydraulic cylinder 8 and the variable-section cam 1 stationary, the camshaft 2 rotates at the moment and drives the cam to rotate through a key, the rocker arm 3 swings around the rocker arm shaft 4 to open and close the valve 6, the used cam profile is higher than that before, and obviously, the lift of the valve 6 is increased than before.

On the contrary, high-pressure oil is introduced above the piston 7 of the hydraulic cylinder 8 to drive the rocker arm 3 to move downwards for a certain displacement, and the second oil duct 24 of the camshaft 2 is introduced with the high-pressure oil to enable the variable-section cam 1 to move reversely for a certain displacement along the line of the camshaft 2, so that one end of the rocker arm 3 is in contact with the variable-section cam 1, then the hydraulic cylinder 8 and the variable-section cam 1 are kept still, the used cam profile is lower than that before, and the lift of the valve 6 can be reduced.

In conclusion, the variable lift valve structure overcomes the defects that the variable valve lift system in the prior art has more increasing mechanisms and large friction loss power. The hydraulic oil distribution mechanism has the advantages of small change on the traditional valve mechanism, few added mechanical parts and friction pairs, almost no additional friction work increase, and the hydraulic oil has a lubricating effect. Furthermore, the section change of the cam is reasonably designed, so that the opening phase of the valve can be changed, and the variable lift and variable valve timing can be realized simultaneously.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. A variable lift valve structure characterized by comprising:

a hydraulic control device;

a rocker mechanism comprising a coaxial clearance fit: rocker arms and rocker arm shafts;

a rocker arm lift mechanism comprising: the hydraulic cylinder is fixedly connected to the cylinder cover, the piston divides the hydraulic cylinder into two chambers, and the two chambers are respectively connected with the hydraulic control device through hydraulic pipelines; one end of the piston rod is connected with the piston, and the other end of the piston rod is circumferentially limited and extends out of the hydraulic cylinder to be connected with the rocker shaft; and

a variable cross-section cam mechanism comprising: the cam surface profile of the variable cross-section cam is continuously, smoothly and variably, and a first cavity and a second cavity which are connected are arranged in the variable cross-section cam; the camshaft passes through the middle of the first chamber and the second chamber to isolate the first chamber and the second chamber; the two ends of the cam shaft are respectively provided with a first oil duct and a second oil duct, one ends of the first oil duct and the second oil duct are connected with a hydraulic control device, a first oil duct opening at the other end of the first oil duct is located in the first cavity, and a second oil duct opening at the other end of the second oil duct is located in the second cavity.

2. The variable lift valve structure of claim 1 wherein the rocker shaft is disposed through the other end of the piston rod.

3. The variable lift valve structure of claim 2, wherein the rocker shaft is an interference fit with the piston rod.

4. The variable lift valve structure of claim 1, wherein a seal ring is disposed between the camshaft and the variable cross-section cam.

5. The variable lift valve structure of claim 1, wherein the camshaft is keyed to a variable cross-section cam to enable the variable cross-section cam to move in a direction of a camshaft axis.

6. The variable lift valve structure of claim 5, wherein two retainer rings are mounted on said camshaft, one on each side of said variable cross-section cam.