Patent Publication Number: US-2022235678-A1

Title: Variable valve actuation mechanism for engine and engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Patent Application Number PCT/CN2020/116234, filed on Sep. 18, 2020, which claims the benefit and priority of Chinese Patent Application Number 201910993201.9, filed on Oct. 18 2019. The entire disclosure of each of the foregoing applications is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the technical field of an engine, in particular to a variable valve actuation mechanism for an engine. Also disclosed is an engine which comprises a variable valve actuation mechanism. 
     BACKGROUND ART 
     At present, there are many kinds of known variable valve technologies for engines, various variable valve technologies realize the variability of lift or timing of variable valve through different structural designs and control methods, so as to enable the engine to achieve better performance or some special functions, one of known type of variable valve technology, is to set cams with different contours on the camshaft of the engine, and switch the control device to make the valves of the engine get the driving lift of the cams with different contours. One of the variable valve technologies is to set a slidable cam on the camshaft, and use the control device to control the cam to slide to switch different cams, such as Audi&#39;s AVS device; another technology is that controlling the rocker arm mechanism to be connected together when in need to realize the switch of lift by setting different rocker arms, such as Honda&#39;s VTEC device; what&#39;s more, by arranging mechanical or hydraulic components in the valve&#39;s actuating device to achieve the actuation and stop of valve through locking and releasing the mechanical or hydraulic components. 
     However, the above-mentioned variable valve devices still have the following shortcomings: 1. Most of them were used in gasoline engines with small valve mechanism loads, and difficult to apply to heavy-duty diesel engines; 2. Multiple control devices with complex structure and high cost (such as AVS devices) are essential to be used, or limitations of the change of valve&#39;s lift (such as VTEC device); 3. The lift accuracy of valve is hard to be guaranteed because the valve device will be easily affected by oil temperature, viscosity, leakage, etc. when driven by hydraulic components. 
     SUMMARY OF INVENTION 
     The invention of the variable valve actuation mechanism for an engine is provided to solve the above deficiencies of the existing variable valve actuation mechanism. The mechanism realizes variable valve by controlling different cam-side rocker arms to transmit corresponding cam lift to valve-side rocker arm. The mechanism has a simple structure and low cost, especially suitable for heavy-duty engine applications. 
     The invention provides a variable valve actuation mechanism for an engine, the mechanism comprises a rocker arm mechanism, a camshaft, a rock arm shaft and a solenoid valve; wherein the rocker arm mechanism which is a combined rocker arm mechanism, includes one valve-side rocker arm and at least one cam-side rocker arm; both the valve-side rocker arm and the cam-side rocker arm are provided with rocker arm shaft mounting holes, the valve-side rocker arm and the cam-side rocker arm are installed side by side on the rocker arm shaft, and can be rotated on the rocker arm shaft; one end of the valve-side rocker arm which is close to the camshaft is provided with a beam structure, and the beam structure being located above the cam-side rocker arms and having a certain clearance with the cam-side rocker arms; the major structure of the cam-side rocker arm are all located on the side which is close to the camshaft, the camshaft is provided with a cam corresponding to each of the cam-side rocker arms, and the contours of each of the cams are different, and each of the cam-side rocker arm is driven up and down by the corresponding cam; sliding block and return springs are provided on the cam-side rocker arms, and the sliding block can move in the gap between the beam structure and the cam-side rocker arm; the rocker arm shaft is provided with a rocker arm shaft oil passage, the sliding block can be driven by the lubrication oil with pressure provided by the rocker arm shaft oil passage; the solenoid valve is provided on the rocker arm shaft oil passage, the rocker arm shaft oil passage is controlled by the solenoid valve in an off or on state. 
     Preferably, wherein the number of the cam-side rocker arm is two, one of which is the first cam-side rocker arm, and the other is the second cam-side rocker arm, when the oil passage controlled by the solenoid valve is in an off state, the sliding block of the first cam-side rocker arm and the second cam-side rocker arm have a first position under the drive of the preload of the return springs; when the oil passage controlled by the solenoid valve is in an on state, the sliding block of the first cam-side rocker arm and the second cam-side rocker arm have a second position under the drive of the lubrication oil, wherein: 
     the first position of the sliding block of the first cam-side rocker arm is located between the beam structure of the valve-side rocker arm and the first cam-side rocker arm, at this position, the sliding block eliminates the gap between the beam structure of the first cam-side rocker arm and the valve-side rocker arm, and enable the first cam-side rocker arms and the valve-side rocker arm to form a transmission chain, and enable the first cam-side rocker arms to be able to transmit the driving lift of the corresponding cam to the valve-side rocker arm; the first position of the sliding block of the second cam-side rocker arm is located below the beam structure of the valve-side rocker arm, and at a position staggered from the beam structure, at this position, the sliding block cannot eliminate the gap between the second cam-side rocker arm and the beam structure of the valve-side rocker arm, and the second cam-side rocker arm and the valve-side rocker arm cannot form a transmission chain; 
     the first position of the sliding block of the first cam-side rocker arm is located below the beam structure of the valve-side rocker arm, and at a position staggered from the beam structure, at this position, the sliding block cannot eliminate the gap between the first cam-side rocker arm and the beam structure of the valve-side rocker arm, and the first cam-side rocker arm and the valve-side rocker arm cannot form a transmission chain; the second position of the sliding block of the second cam-side rocker arm is located between the beam structure of the valve-side rocker arm and the second cam-side rocker arm, at this position, the sliding block eliminates the gap between the second cam-side rocker arm and the beam structure of the valve-side rocker arm, and enable the second cam-side rocker arm and the valve-side rocker arm to form a transmission chain, and enable the second cam-side rocker arm to be able to transmit the driving lift of the corresponding cam to the valve-side rocker arm; thus enabling the combined rocker arm mechanism to be able to selectively transmit the driving lift of a cam that corresponds to the first cam-side rocker arm or the second cam-side rocker arm to the valve-side rocker arm. 
     Preferably, wherein both of the upper part of the first cam-side rocker arm and the second cam-side rocker arm are provided with a plunger hole, and the plunger hole is a stepped hole; a driving plunger is slidably arranged in the plunger hole, the driving plunger of the first cam-side rocker arm is a stepped shaft, and the large-diameter section and the small-diameter section respectively have a gap match with the large-diameter hole and the small-diameter hole of the plunger hole; one end of the plunger hole with a larger-diameter of the first cam-side rocker arm is provided with a plug, the plug is provided with an exhaust hole; the return spring of the first cam-side rocker arm is located between the larger-diameter end of the driving plunger and the plug, and the smaller diameter end of the driving plunger of the first cam-side rocker arm is connected to the sliding block through the smaller diameter hole of the plunger hole; 
     one end of the plunger hole of the second cam-side rocker arm is a cylindrical hole, and the other end is a waist-shaped hole; one end of the cylindrical hole of the plunger hole of the second cam-side rocker arm is provided with a sealed plug, and the driving plunger of the second cam-side rocker arm is a stepped shaft, the large-diameter section of the stepped shaft is a cylinder, which has a clearance fit with the cylinder hole of the plunger hole, the two sides of the small-diameter section of the stepped shaft are processed to be flat, and the sectional area of the flat is smaller than that of the waist-shaped hole at the other end of the plunger hole; the return spring of the second cam-side rocker arm is located between the driving plunger and the waist-shaped hole at the other end of the plunger hole, the end of the driving plunger which is processed into a flat of the second cam-side rocker arm is connected with the sliding block through the waist-shaped hole at the other end of the plunger hole; 
     both of the first cam-side rocker arm and the second cam-side rocker arm are provided with rocker arm oil passage, one end of the rocker arm oil passage is connected to the cavity formed by the end of the driving plunger without return spring and the plunger hole, and the other end is connected to the rocker arm shaft oil passage. 
     Preferably, wherein the sliding block is a rectangular block with an arc surface or an inclined surface on one side; the end of the sliding block connected with the driving plunger is machined with a slot and a pin hole, and is connected with the driving plunger through a pin; the front end face of the sliding block in the forward direction which driven by the driving plunger is a circular arc surface or an inclined surface, the bottom surface of the sliding block is a plane, the top surface of the sliding block and the bottom surface of the beam structure of the valve-side rocker arm are planes, or the top surface of the sliding block is provided with an arc or wedge-shaped concave or convex, and the bottom surface of the beam structure of the valve-side rocker arm is provided with an arc or wedge-shaped convex which is matched with the top surface of the sliding block. 
     Preferably, wherein the combined rocker arm mechanism has two cam-side rocker arms, the rocker arm shaft is provided with one rocker arm shaft oil passage, the rocker arm shaft oil passage is provided with one solenoid valve, and the rocker arm shaft oil passage is connected to the rocker arm oil passages of both of the two cam-side rocker arms, or the rocker arm shaft is provided with two rocker arm shaft oil passages, both of the two rocker arm shaft oil passages are respectively provided with a solenoid valve, and both of the two rocker arm shaft oil passages are respectively connected with the rocker arm oil passage of the two cam-side rocker arms; when the combined rocker arm mechanism has more than two cam-side rocker arms, the rocker arm shaft is separately provided with a rocker arm shaft oil passage for each cam-side rocker arm, and respectively connected with the rocker arm oil passage of each cam-side rocker arm, and each rocker arm shaft oil passage is provided with a solenoid valve. 
     Preferably, wherein the middle part of the valve-side rocker arm is a gap, and a side wall is provided on both sides of the gap; the rocker arm shaft mounting hole is arranged on the side walls of the gap, the beam structure is located at the end of the valve-side rocker arm which near the camshaft, and the beam structure is connected with the two side walls of the valve-side rocker arm, the cam-side rocker arms are installed at the gap between the two side walls of the valve-side rocker arm. 
     Preferably, wherein the valve-side rocker arm is a plate structure, the rocker arm shaft mounting hole is arranged in the middle of the plate structure, the beam structure is T-shaped structure, the cam-side rocker arms are respectively installed on the left and right side of the valve-side rocker arm. 
     Preferably, wherein a rocker arm spring is arranged between the valve-side rocker arm and the cam-side rocker arm of the combined rocker arm mechanism, the rocker arm spring is a spiral spring or a torsion spring, the rocker arm spring is installed between the valve-side rocker arm and the cam-side rocker arm or on the rocker arm shaft, one end of the rocker arm spring acts on the valve-side rocker arm, and the other end acts on the cam-side rocker arm, the rocker arm spring has a certain preload force, so that the valve-side rocker arm is always kept in contact with the valve mechanism, and the cam-side rocker arm is always kept in contact with the cam. 
     Preferably, wherein the cam-side rocker arm is provided with a roller, which is in contact with the corresponding cam on the cam shaft and is driven by the cam, alternatively, the cam-side rocker arm is provided with a ball socket or a ball joint structure, and the ball socket or ball joint structure is connected with a push rod driven by the cam shaft, and the ball socket or ball joint structure is driven by the push rod. 
     The invention also provides a variable valve actuation mechanism for another engine, the mechanism comprises a rocker arm mechanism, a camshaft, a rock arm shaft and a solenoid valve; wherein the rocker arm mechanism which is a combined rocker arm mechanism, includes one valve-side rocker arm and two cam-side rocker arm which are the first cam-side rocker arm and the second cam-side rocker arm; the valve-side rocker arm and the cam-side rocker arm are installed side by side on the rocker arm shaft, and can be rotated on the rocker arm shaft; the major structure of the cam-side rocker arm are all located on the side which is close to the camshaft, the camshaft is provided with a cam corresponding to each of the cam-side rocker arms, and the contours of each of the cams are different, and each of the cam-side rocker arm is driven up and down by the corresponding cam; the tops of the first cam-side rocker arm and the second cam-side rocker arm are respectively provided with a lug boss, and the two lug bosses are staggered front and rear; the upper part of the valve-side rocker arm is provided with a plunger hole, and the plunger hole is a stepped hole; a driving plunger which is a step shaft which is slidably arranged in the plunger hole, one end of the driving plunger is connected to the sliding block through the plunger hole, and a return spring is installed at one end of the plunger hole, and the other end the plunger hole is connected with the rocker arm oil passage; the rocker arm oil passage is arranged in the valve-side rocker arm, the rocker arm oil passage is connected with the rocker arm shaft oil passage, the rocker arm shaft oil passage is arranged in the rocker arm shaft, the sliding block can be driven by the lubrication oil with pressure from the rocker arm shaft oil passage; the solenoid valve is provided on the rocker arm shaft oil passage, the rocker arm shaft oil passage is controlled by the solenoid valve in an off or on state; 
     when the rocker arm shaft oil passage is in an off state, the sliding block has a first position under the drive of the preload of the return spring, at this position, the sliding block eliminates the gap between the first cam-side rocker arm and the valve-side rocker arm, and enable the first cam-side rocker arm and the valve-side rocker arm to form a transmission chain; the upper part of the lug boss of the second cam-side rocker arm is a gap of the sliding block, and the second cam-side rocker arm and the valve-side rocker arm cannot form a transmission chain; 
     when the rocker arm shaft oil passage is in an on state, the sliding block has a second position under drive of the lubrication oil, at this position, the sliding block eliminates the gap between the second cam-side rocker arm and the valve-side rocker arm, and enable the second cam-side rocker arm and the valve-side rocker arm to form a transmission chain; the upper part of the lug boss of the first cam-side rocker arm is a gap of the sliding block, and the first cam-side rocker arm and the valve-side rocker arm cannot form a transmission chain. 
     Preferably, wherein one side of the lug boss of the cam-side rocker arm is a circular arc surface, and the center of the circular arc surface is concentric with the center of the rocker arm shaft hole; the sliding block is installed in a chute above the valve-side rocker arm, and located above the lug boss of the cam-side rocker arm; the sliding block is a cuboid block, and the left and right sides of the sliding block are respectively provided with a gap, a circular arc surface is provided on the gap at a position corresponding to the circular arc side surface of the upper lug boss of the cam-side rocker arm, and the circular arc surface has the same radius as the circular arc surface of the lug upper boss of the cam-side rocker arm. 
     The invention also provides an engine which includes any one of the above-mentioned variable valve actuation mechanism for the engine. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The attached drawings are intended to provide a better understanding of the invention and are used to describe and explain the invention together with the specific embodiments below, but do not constitute a limitation of the invention. In the attached drawings of different embodiments or design schemes, some parts have the same marks with other embodiments, which only means that they are parts with the same functions in different embodiments, but does not mean that they are the same part or have the same structure. The specific details shall be subject to the attached drawings and specifications. In the appended drawings: 
         FIG. 1  is a structural schematic diagram of the first embodiment of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 2  is a schematic diagram of a combined rocker mechanism assembled in the first embodiment of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 3  is the assembly exploded diagram of the combined rocker arm mechanism of the first embodiment of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 4  is a schematic diagram of valve-side rocker arm structure of the first embodiment of variable valve actuation mechanism for the engine of the invention; 
         FIG. 5  and  FIG. 6  are respectively the schematic diagram of the first cam-side rocker arm structure of the first embodiment of the variable valve actuation mechanism for the engine of the invention and the sectional view installed on the combined rocker arm mechanism (the sliding block is in the first position); 
         FIG. 7  is and  FIG. 8  are respectively the schematic diagram of the second cam-side rocker arm structure of the first embodiment of the variable valve actuation mechanism for the engine of the invention and the sectional view installed on the combined rocker arm mechanism (the sliding block is in the first position); 
         FIG. 9  is a schematic diagram of the sliding block of the first embodiment of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 10  and  FIG. 11  are the structural sectional views when the sliding blocks of the first cam-side rocker arm and the second cam-side rocker arm of the first embodiment of the variable valve actuation mechanism for the engine of the invention are in the second position respectively; 
         FIG. 12  is the structural sectional view when the sliding block of the first embodiment of the variable valve actuation mechanism for the engine of the invention is stopped by the beam structure during position switching; 
         FIG. 13  is the structural schematic drawing and assembly exploded drawing of another design scheme of the combined rocker arm mechanism of variable valve actuation mechanism for the engine of the invention; 
         FIG. 14  is the structure and installation schematic diagram of another design scheme of rocker arm spring of variable valve actuation mechanism for the engine of the invention; 
         FIG. 15  is a structural schematic diagram of a combined rocker arm with a cam-side rocker arm of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 16  is a structural schematic diagram of the variable valve actuation mechanism for the engine of the invention, in which two cam-side rocker arms are respectively equipped with a rocker arm shaft oil passage and solenoid valve in the rocker arm shaft; 
         FIG. 17  is a schematic diagram of the structure when the cam-side rocker arm of the variable valve actuation mechanism for the engine of the invention is driven by a push rod. 
         FIG. 18  is a structural schematic diagram of the second embodiment of the variable valve actuation mechanism for the engine of the invention (the camshaft and solenoid valve are not shown); 
         FIG. 19  and  FIG. 20  are respectively the structural schematic diagrams of the first cam-side rocker arm and the second cam-side rocker arm of the second embodiment of the variable valve actuation mechanism for the engine of the invention; 
         FIG. 21  is the valve-side rocker arm structure diagram of the second embodiment of the variable valve actuation mechanism for the engine of the invention and the sectional view along the rocker arm oil passage and the center of the plunger hole in the assembly state; 
         FIG. 22  is a structural schematic diagram of the sliding block of the second embodiment of the variable valve actuation mechanism for the engine of the present invention; 
         FIG. 23  is a sectional view of the structure when the sliding block of the second embodiment of the variable valve actuation mechanism for the engine of the invention is in the first position; 
         FIG. 24  is a sectional view of the structure when the sliding block of the second embodiment of the variable valve actuation mechanism for the engine of the invention is in the second position. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The specific technical solution adopted in the embodiments of the present invention will be described in detail and completely below with reference to the accompanying drawings of the present invention. In the description of the present invention, unless otherwise specified, the meaning of “plurality” refers to two or more, the terms of “upper”, “lower”, “left”, “right”, “inner”, “outer”, etc. are used to indicate the orientation or positional relationship only for the convenience of description and explanation. The orientation or positional relationship shown in the figures should not be construed as a specific orientation or positional relationship that the indicated device or element must have, and does not constitute a limitation to the present invention. 
       FIG. 1  depicts the first embodiment of the variable valve actuation mechanism for the engine provided by the present invention, the variable valve actuation mechanism for the engine includes a rocker arm mechanism, a camshaft  2 , a rocker arm shaft  3  and a solenoid valve  4 , the rocker arm mechanism is a combined rocker arm mechanism  1 . In this embodiment, the combined rocker arm mechanism  1  includes one valve-side rocker arm  11  and two cam-side rocker arms: the first cam-side rocker arm  12  and the second cam-side rocker arm  13 .  FIG. 2  and  FIG. 3  respectively show the schematic structural diagram of the combined rocker arm mechanism  1  and the exploded view of each component,  FIG. 4  shows the schematic structural diagram of the valve-side rocker arm  11 , as shown in  FIG. 2 ,  FIG. 3  and  FIG. 4 , the valve-side rocker arm  11 , the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are equipped with mounting holes of the rocker arm shaft. The end of valve-side rocker arm  11  near the valves can be connected with valve or an intermediate part that drives the valve, such as valve bridge, to drive the valve to open and close. 
     The valve-side rocker arm  11  is provided with a gap in the middle, a side wall is provided on each side, and a rocker shaft mounting hole is provided on the side wall. A beam structure  111  is provided at the end of the valve-side rocker arm  11  close to the camshaft  2 , which is connected to the two side walls of the valve-side rocker arm. The beam structure  111  is located above the two cam-side rocker arms  12  and  13 , and has a certain gap with the two cam-side rocker arms  12  and  13 , and the two cam-side rocker arms  12  and  13  are located side by side on the gap between the two sides of the valve-side rocker arm  11 , which are installed on the rocker arm shaft  3  together with the valve-side rocker arm  11  and can be rotated on the rocker arm shaft  3 . 
     The main structures of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are both located on the side close to the camshaft  2 , a cam  21  and cam  22  with different contours are provided at the position of the camshaft  2  corresponding to the position of the first cam-side rocker arm  12  and the second cam-side rocker arm  13 . As shown in  FIG. 1 , the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are connected with the corresponding cams on the camshaft  2  to receive the driving lift of the corresponding cams. Generally, the cam  21  corresponding to the first cam-side rocker arm  12  is set as the cam for normal fire operation of the engine, and the cam  22  corresponding to the second cam side rocker arm  13  is set as a cam for other functions designed as required, such as cams for engine braking or to improve engine performance. 
       FIG. 5  and  FIG. 6  respectively show a schematic structural diagram of the first cam-side rocker arm  12  and a cross-sectional view when it is installed on the combined rocker arm mechanism  1  (the sliding block is in the first position). The upper part of the first cam-side rocker arm  12  is provided with a plunger hole, the plunger hole is a stepped hole structure, a driving plunger  121  is slidably installed in the plunger hole, and the driving plunger  121  is a stepped shaft structure, and its large diameter section and small diameter section are respectively have clearance fit with the large-diameter hole and the small-diameter hole of the plunger. The larger diameter end of the plunger hole of the first cam-side rocker arm  12  is equipped with a plug  124 , and the plug is provided with an exhaust hole, the return spring  122  of the first cam-side rocker arm  12  is disposed between the larger diameter end of the driving plunger  121  and the plug  124 , the smaller diameter end of the driving plunger  121  of the first cam-side rocker arm  12  is connected to the sliding block  123  through the smaller diameter hole of the plunger hole. 
       FIG. 7  and  FIG. 8  respectively show a schematic structural diagram of the second cam-side rocker arm  13  and a cross-sectional view when it is installed on the combined rocker arm mechanism  1  (the sliding block is in the first position). The upper part of the second cam-side rocker arm  13  is provided with a plunger hole, one end of the plunger hole is a cylindrical hole, the other end is a waist-shaped hole, one end of the cylindrical hole of the plunger hole is equipped with a sealed plug  134 , and a driving plunger  131  is slidably installed in the plunger hole, one end of the driving plug  131  is a cylinder, which has a clearance fit with the cylindrical hole of the plunger hole, the other end of the driving plunger  131  is processed into a flat shape, the flat cross-sectional area is smaller than the cross-sectional area of the waist-shaped hole at the other end of the plunger hole. The return spring  132  of the second cam-side rocker arm  13  is disposed between the driving plunger  131  and the waist-shaped hole at the other end of the plunger hole. One end of the driving plunger  131  is processed into a flat shape and is connected to the sliding block  133  through the waist-shaped hole at the other end of the plunger hole. 
       FIG. 9  shows a schematic diagram of the structure of the sliding block  123  and sliding block  133 , the sliding block is a rectangular block with a circular arc surface or an inclined surface on one side, one end of the sliding block connected to the driving plunger is machined with a slot and a pin hole, and connected to the driving plunger through a pin. The front end face C of the sliding block in the forward direction of the driving plunger is a circular arc surface or an inclined surface, the bottom surface of the sliding block is a plane, the top surface of the sliding block and the bottom surface of the beam structure  111  of the valve-side rocker arm  11  are both planes, or, the top surface of the sliding block is provided with an arc or wedge-shaped concave or convex, the bottom surface of the beam structure  111  of the valve side rocker arm  11  is provided with a circular arc or wedge-shaped convex or concave that matches the shape of the top surface of the sliding block, to prevent the sliding block from accidentally slipping out during the transmission process in contact with the beam structure. 
     The rocker arm shaft  3  is provided with a rocker arm shaft oil passage  31 , which is connected to the lubricating oil with a certain pressure of the engine, the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are provided with rocker arm oil passages  125  and  135 . As shown in  FIG. 6  and  FIG. 8 , one end of the rocker arm oil passage are communicated with the cavity formed by the plunger hole and the end of the drive plunger without the return spring, and the other end is connected to the rocker arm shaft oil passage. The rocker arm shaft oil passage  31  is provided with a solenoid valve  4 , and the solenoid valve  4  controls the connection or closing of the rocker shaft oil passage  31  and the lubricating oil with a certain pressure. 
     When the solenoid valve  4  controls the rocker arm shaft oil passage  31  to close, there is no oil pressure in the rocker arm oil passage, the driving plungers  121  and  131  of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are preloaded by the return springs  122  and  132  to push the sliding block  123  and  133  to one end of the plunger hole. As shown in  FIG. 6  and  FIG. 8 , at this time, the position of the sliding block  123  and  133  under the action of the preloading force of the return springs  122  and  132  is the first position, when the solenoid valve  4  controls the rocker arm shaft oil passage  31  to be turned on, the lubricating oil with a certain pressure of the engine enters the rocker arm oil passage, so that the driving plungers  121  and  131  of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are acted by the hydraulic force of the lubricating oil, and the driving plunger overcomes the return spring force and pushes the sliding block  123  and  133  to slide to the other end of the plunger hole. As shown in  FIG. 10  and  FIG. 11 , at this time, the positions of the sliding block  123  and  133  under the action of the lubricating oil hydraulic force are the second positions. 
     The first position of the sliding block  123  of the first cam-side rocker arm  12  is located between the beam structure  111  of the valve-side rocker arm  11  and the first cam-side rocker arm  12 . As shown in  FIG. 6 , at this position, the sliding block  123  eliminates the gap between the first cam-side rocker arm  12  and the beam structure  111  of the valve-side rocker arm  11 , so that the first cam-side rocker arm  12  and the valve-side rocker arm  11  form a transmission chain, while the first position of the sliding block  133  of the second cam-side rocker arm  13  is located below the cross-beam structure  111  of the valve-side rocker arm  11  at a position staggered from the cross-beam structure, as shown in  FIG. 8 , at this position, the sliding block  133  cannot eliminate the gap between the second cam-side rocker arm  13  and the beam structure  111  of the valve-side rocker arm  11 , making the second cam-side rocker arm  13  and the valve-side rocker arm  11  cannot form a transmission chain. 
     The second position of the sliding block  123  of the first cam-side rocker arm  12  is located below the cross-beam structure  111  of the valve-side rocker arm  11  at a position staggered from the cross-beam structure, as shown in  FIG. 10 , at this position, the sliding block  123  cannot eliminate the gap between the first cam-side rocker arm  12  and the beam structure  111  of the valve-side rocker arm  11 , which lead to the first cam-side rocker arm  12  and the valve-side rocker arm  11  cannot form a transmission chain, while the second position of the sliding block  133  of the second cam-side rocker arm  13  is located between the cross beam structure  111  of the valve-side rocker arm  11  and the second cam-side rocker arm  13 , as shown in  FIG. 11 , at this position, the sliding block  133  eliminates the gap between the second cam-side rocker arm  13  and the beam structure  111  of the valve-side rocker arm  11 , making the second cam-side rocker arm  13  and the valve-side rocker arm  11  form a transmission chain. 
     In addition, rocker arm spring  14  and  15  are respectively provided between the valve-side rocker arm  11 , the first cam-side rocker arm  12  and the second cam-side rocker arm  13  of the combined rocker arm mechanism  1 , as shown in  FIG. 3 ,  FIG. 6  and  FIG. 8 , the rocker arm spring  14  and  15  are coil springs, the rocker spring  14  and  15  are installed between the valve-side rocker arm  11 , the first cam-side rocker arm  12  and the second cam-side rocker arm  13 . One end of the rocker spring  14  and  15  acts on the valve-side rocker arm  11 , and the other end acts on the first cam-side rocker arm  12  and the second cam-side rocker arm  13 . The rocker arm spring  14  and  15  have a certain preload, so that the valve-side rocker arm  11  is always kept in contact with the valve mechanism, and the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are always kept in contact with the cams. 
     In the first embodiment of the engine variable valve actuation mechanism provided by the present invention, the working process and principle of the device are as follows: when the engine is in normal operation, the solenoid valve  4  on the rocker shaft oil passage  31  is in a power-off state, at this time, the sliding block  123  and  133  of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are in the first position under the preloading force of the return springs  122  and  132 , as shown in  FIG. 6  and  FIG. 8 , as before, when the sliding block  123  is in the first position, the gap between the first cam-side rocker arm  12  and the beam structure  111  of the valve-side rocker arm  11  is eliminated, so that the first cam-side rocker arm  12  and the valve-side rocker arm  11  form a transmission chain, and the first cam-side rocker arm  12  can transmit the driving lift of the corresponding cam  21  to the valve-side rocker arm  11 , the engine operates based on the lift of the cam  21  corresponding to the first cam-side rocker arm  12 . While the sliding block  133  of the second cam-side rocker arm  13  is in the first position, the second cam-side rocker arm  13  and the valve-side rocker arm  11  cannot form a transmission chain, which is in useless motion (lost motion) state when driven by the cam  22 . 
     When the engine needs to switch to the lift operation of the cam  22  corresponding to the second cam-side rocker arm  13 , the solenoid valve  4  on the rocker arm shaft oil passage  31  is energized, and the rocker arm shaft oil passage  31  is filled with the lubricating oil with a certain pressure of the engine. The driving plungers  121  and  131  of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are hydraulically acted by the lubricating oil to push the sliding block  123  and  133  to the second position, as shown in  FIG. 10  and  FIG. 11 . As shown before, when the sliding block  123  of the first cam-side rocker arm  12  is in the second position, the first cam-side rocker arm  12  and the valve-side rocker arm  11  cannot form a transmission chain, the first cam-side rocker arm  12  is in lost motion state when driven by the cam  21 , but when the sliding block  133  of the second cam-side rocker arm  13  is in the second position, the gap between the second cam-side rocker arm  13  and the beam structure  111  of the valve-side rocker arm  11  is eliminated. The second cam-side rocker arm  13  and the valve-side rocker arm  11  form a transmission chain, so that the second cam-side rocker arm  13  can transmit the driving lift of the corresponding cam  22  to the valve-side rocker arm  11 , the engine runs according to the lift of the cam  22  corresponding to the rocker arm  13  on the second cam side to realize the variable valve. The existence of the rocker arm springs  14  and  15  can keep the cam-side rocker arm in the lost motion state in constant contact with the corresponding cam during movement, so as to avoid uncontrolled flying off and cause collision damage between components. 
     When the sliding block  123  and  133  of the cam-side rocker arm are switched from the first position to the second position, and the cam  21  and  22  corresponding to the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are both in the base circle part, at this time, the valve is in the closed state, there is no force between the cam and the rocker arm, the sliding block does not receive resistance when moving, the position switch can be smoothly accomplished; when the cam  21  corresponding to the first cam-side rocker arm  12  has lift, at this time, the first cam-side rocker arm  12  is driving the valve-side rocker arm  11  to open or close the valve, there will be a large force between the sliding block of the first cam-side rocker arm  12  and the beam structure  111  of the valve-side rocker arm  11 , but the driving force of driving plunger  121  from the lubrication oil is limited and cannot push the sliding block  123  to exit from the transmission chain. 
     Only when the cam  21  rotates to the base circle part, and there is no force between the sliding block  123  and the beam structure  111 , the sliding block  123  can be pushed by the driving plunger  121  to exit from the transmission chain; on the contrary, when the sliding block  123  and  133  are switched from the second position to the first position, the same principle as before, only when the cam  22  corresponding to the second cam-side rocker arm  13  rotates to the base circle, the sliding block  133  can exit from the transmission chain. Therefore, the variable valve actuation mechanism for the engine of the present invention can avoid the impact damage of the valve train caused by the sudden change of the valve lift due to the fact that the cam is not in the base circle portion during switching. Further, the top surface of the sliding block and the bottom surface of the beam structure of the valve-side rocker arm  11  can be provided with arc or wedge-shaped protrusions or concave shapes that match with each other, so as to ensure that the sliding block will not accidentally exit during the transmission movement, which improves the reliability of the device. 
     In addition, when the sliding block of the cam-side rocker arm is switched between the first position and the second position, when the cam corresponding to the cam-side rocker arm in the lost motion state has a lift, and the cam corresponding to the cam-side rocker arm in the transmission chain is in the base circle part, at this time, the sliding block of the cam-side rocker arm in the transmission chain can smoothly exit from the transmission chain, 
     while the sliding block of the cam-side rocker arm out of the transmission chain is pushed by the drive plunger, at this time, it will be stopped by the beam structure  111  of the valve-side rocker arm  11 , As shown in  FIG. 12 , at this time, the arc surface or inclined surface (C surface) at one end of the sliding block is in contact with the beam structure, and will be in contact with the beam structure along with the swing of the cam-side rocker arm. There is a sliding between them, until the cam corresponding to the cam-side rocker arm that wants to enter the transmission chain rotates to the base circle part, the blocking of the beam structure to the sliding block disappears, and the sliding block can be pushed to make the cam-side rocker arm and the valve-side rocker arm form a transmission chain. The function of setting the C surface of the sliding block in contact with the beam structure as a circular arc or inclined plane is: the center of the arc surface is designed to be concentric with the center of the rocker arm shaft. When there is a relative sliding between the two sides, the position of the sliding block remains unchanged on the cam-side rocker arm, so the driving plunger will not push the lubricating oil to backflow and cause a large resistance to cause wear of the components, which improves the reliability of the device. It has a similar effect and makes the processing relatively simple when the C-plane is set as a inclined plane. 
     Further, in the first embodiment of the present invention, the valve-side rocker arm  11  of the combined rocker arm mechanism  1  can be designed as a plate-like structure. As shown in  FIG. 13 , a rocker shaft mounting hole is provided in the middle of the plate-like structure, a T-shaped beam structure  111  is arranged on the upper part of the plate structure at one end of the valve side rocker arm  11  close to the camshaft. The T-shaped beam structure  111  is located above the cam-side rocker arm. In this way, the structure of the combined rocker arm mechanism can be more compact and adaptable. 
     Further, in the first embodiment of the present invention, the rocker spring  14  and  15  can be designed as torsion springs. As shown in  FIG. 14 , the rocker spring  14  and  15  are installed on the rocker shaft  3 , one end of the rocker spring  14  and  15  acts on the valve-side rocker arm  11 , and the other end acts on the first cam-side rocker arm  12  and the second cam-side rocker arm  13 . The advantage of this design can reduce the height of the combined rocker arm mechanism  1  and improve the adaptability. 
     Further, in the specific implementation, the number of the cam-side rocker arms in the combined rocker arm mechanism  1  can not only be set to two, but also can be set to have only one first cam-side rocker arm  12  or more than two. For the cam-side rocker arm, when there is only one first cam-side rocker arm  12 , as shown in  FIG. 15 , the sliding block  123  of the first cam-side rocker arm  12  can keep the valve closed when it is switched to the second position, which may make the engine realize the cylinder deactivation function, when the number of cam-side rocker arms is more than 2, more different valve lifts can be provided for the engine, so that the engine can have more working modes and functions. 
     Further, in the specific implementation, for the design of the rocker arm shaft oil passage  31  and the arrangement of the solenoid valve  4 , when the combined rocker arm mechanism  1  has different numbers of cam-side rocker arms, there can be different design solutions: when the rocker arm mechanism  1  has two cam-side rocker arms, a rocker arm shaft oil passage can be provided in the rocker arm shaft  3 . As shown in  FIG. 1 , a solenoid valve is arranged on the rocker arm shaft oil passage, and the rocker arm shaft oil passage, at the same time, it is connected with the rocker arm oil passages of the two cam-side rocker arms, so that when the solenoid valve  4  is turned on, the sliding blocks of the two cam-side rocker arms are switched in position; in addition, when the combined rocker arm mechanism has two cam-side rocker arms. the rocker arm shaft also can be provided with two rocker arm shaft oil passages, as shown in  FIG. 16 , the two rocker arm shaft oil passages are respectively communicated with the rocker arm oil passages of the first cam-side rocker arm  12  and the second cam-side rocker arm  13 , there is a solenoid valve on each of the two rocker shaft oil passages, and each solenoid valve controls a cam-side rocker arm. This design can have the advantage that the combined rocker arm mechanism  1  can have three working modes by controlling the two solenoid valves on or off: 1. The valve-side rocker arm is driven by the first cam-side rocker arm, 2. The valve-side rocker arm is driven by the second cam-side rocker arm, 3. Both the first cam-side rocker arm and the second cam-side rocker arm are in lost motion state (the valves are kept closed). However, when the combined rocker arm mechanism has more than two cam-side rocker arms, it needs to arrange a rocker arm shaft oil passage for each cam-side rocker arm in the rocker arm shaft, which is respectively connected with rocker arm oil passage of each cam-side rocker arm, and each rocker arm shaft oil passage is provided with a solenoid valve. This is because: when the first cam-side rocker arm exits from the transmission with the valve-side rocker arm, only one of the second cam-side rocker arms can be selected, which is used to drive the valve-side rocker arm, or all the cam-side rocker arms are in lost motion state, and there cannot be a state where two cam-side rocker arms drive the valve-side rocker arms at the same time. 
     Further, in the specific implementation, the structure of the cam-side rocker arm can be designed as a rocker arm with rollers, as shown in  FIG. 1 , it is driven directly by cam and is suitable for overhead camshaft engine. the structure of the cam-side rocker arm can be designed to has a ball socket or ball joint structure, as shown in  FIG. 17 , the ball socket or ball joint structure is connected with a push rod driven by a camshaft, which is suitable for an engine with a non-overhead camshaft structure engine. 
       FIG. 18  depicts the second embodiment of the variable valve actuation mechanism for the engine provided by the present invention (the camshaft and the solenoid valve are not shown). In this embodiment, the difference from the first embodiment is that the combined rocker arm mechanism  1 , the combined rocker arm mechanism  1  includes a valve-side rocker arm  11  and two cam-side rocker arms: a first cam-side rocker arm  12  and a second cam-side rocker arm  13 ,  FIG. 19  and  FIG. 20  respectively show the schematic structural diagrams of the first cam-side rocker arm  12  and the second cam-side rocker arm  13 , the upper parts of the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are not provided with a sliding block and a return spring, but are provided with a boss  124  and  134 , one side surface  124 C and  134 C of the boss  124  and  134  are arc surfaces, and the center of the arc surface is concentric with the center of the rocker arm shaft hole, the boss  124  and  134  have a certain clearance with the valve-side rocker arm  11 , the lower part of the middle of the valve-side rocker arm  11  is a gap, each side is provided with a side wall, the side wall is provided with a rocker shaft mounting hole, the first cam-side rocker arm  12  and the second cam-side rocker arm  13  are installed side by side at the notch position between the two side walls of the valve-side rocker arm  11 . 
       FIG. 21  shows the structure diagram of the valve-side rocker arm  11  and the cross-sectional view along the rocker arm oil passage and the center of the plunger hole in this embodiment. The upper part of the valve-side rocker arm  11  is provided with a plunger hole, and the plunger hole is a stepped hole, a driving plunger  112  is installed slidably in the plunger hole, the driving plunger  112  is a stepped shaft, one end of the driving plunger passes through the driving plunger hole, and is connected to the movable block  114 , a return spring  113  is provided between the driving plunger  112  and the plunger hole, a rocker arm oil passage  115  is arranged on the valve-side rocker arm  11 . One end of the rocker arm oil passage  115  is communicated with the cavity formed by the plunger hole and one end of the driving plunger  112 , and the other end is communicated with the rocker arm shaft oil passage  31 . 
       FIG. 22  shows a schematic diagram of the structure of the movable block  114  in this embodiment. The movable block  114  is installed in the chute above the valve-side rocker arm  11 , is located above the cam-side rocker arms&#39; boss  124  and  134 , and the movable block  114  is a rectangular parallelepiped. There are gaps  1142  and  1143  on the left and right sides of the movable block  114  respectively, the gap  1142  and  1143  are provided with arc surface  1142 C and  1143 C corresponding to the arc sides  124 C and  134 C of the boss of the cam-side rocker arm, surface  1142 C and  1143 C have the same radius as the arc sides  124 C and  134 C of the boss on the cam-side rocker arm. 
     When the rocker arm shaft oil passage  31  is closed, the movable block  114  has a first position under the action of the preload of the return spring  113 , as shown in  FIG. 23 , at this position, the movable block  114  eliminates the gap between the first cam-side rocker arm  12  and the valve-side rocker arm  11 , so that the first cam-side rocker arm  12  and the valve-side rocker arm  11  form a transmission chain, the notch  1143  of the movable block  114  above the boss  134  of the second cam-side rocker arm  13  makes the second cam-side rocker arm  13  and the valve-side rocker arm  11  be unable to form a transmission chain, which is in lost motion state when driven by the Cain; when the rocker arm shaft oil passage  31  is communicated, the movable block  114  is hydraulically actuated to have a second position, as shown in  FIG. 24 , at this position the movable block  114  eliminates the gap between the second cam-side rocker arm  13  and the valve-side rocker arm  11 , so that the second cam-side rocker arm  13  and the valve-side rocker arm  11  form a transmission, the notch  1142  of the movable block  114  above the boss  124  of the first cam-side rocker arm  12  makes the first cam-side rocker arm  12  and the valve-side rocker arm  11  be unable to form a transmission chain, which is in lost motion state when driven by the cam. 
     In the second embodiment of the present invention, it has the same working principle and process as the first embodiment, which will not be repeated. The difference from the first embodiment is that a single movable block  114  disposed on the valve-side rocker arm  11  replaces the aforementioned sliding blocks respectively disposed on each cam-side rocker arm in this embodiment, thereby reducing the number of parts and making the structure of the cam-side rocker arm simpler. 
     In addition, the present invention also provides an engine including the above-mentioned variable valve actuation mechanism for the engine. 
     It should be noted that the above-mentioned embodiments are only preferred embodiments adopted to illustrate the design scheme and principle of the present invention, and should not be construed as limiting the present invention. Under the premise, the technical solutions described in the above embodiments can still be further modified, or some of the technical features thereof can be replaced, combined, etc., and these should be regarded as the protection scope of the present invention.