Variable lift valve device of engine and motorcycle engine

Abstract

The invention discloses a variable-lift valve device of an engine. The variable-lift valve device comprises a cam assembly, a valve rocker arm, a high-lift rocker arm and a low-lift rocker arm. The valve rocker arm is provided with a movable linkage pin; when the linkage pin retreats from the position below the high-lift rocker arm, the low-lift rocker arm drives the valve rocker arm to swing, and the high-lift rocker arm swings in an empty mode. When the linkage pin enters the position below the high-lift rocker arm, the high-lift rocker arm abuts against the linkage pin to drive the valve rocker arm to swing, and the low-lift rocker arm swings in an empty mode. Compared with a variable valve lift rocker arm structure in the prior art, under the high-speed working condition, the inertia applied to the valve spring can be reduced, the design force value of the valve spring can be reduced, the consumed power of the variable valve lift rocker arm mechanism can be reduced, and the power performance of an engine can be improved to a greater extent. The invention further discloses a motorcycle engine comprising the engine variable lift valve device.

Description

Technical Field

[0001] The invention relates to a variable lift valve device for an engine, in particular to a variable lift valve device for a motorcycle engine. Background Art

[0002] Valve lift refers to the maximum height of the engine valve when it is open, which directly affects the engine's intake and exhaust volumes, and thus affects the engine's performance. The engine's requirements under different operating conditions are that in high-speed areas, a larger valve lift is required to improve intake efficiency and combustion efficiency; while in low-speed areas, a smaller valve lift helps to improve torque and fuel economy. However, the valve lift of traditional motorcycle engines is fixed and cannot be changed. There is only one type of intake or exhaust cam profile on the camshaft, which takes into account the balance of high-speed and low-speed operating conditions. The result is that neither the best high-speed power nor the best low-speed torque can be obtained.

[0003] The introduction of variable valve lift technology is to solve this problem. The variable valve lift structure on a motorcycle engine generally uses two intake or exhaust cam profiles on the camshaft to achieve low-speed and high-speed valve lift requirements. Patent document EP2821601B1 discloses a variable valve lift structure for a motorcycle engine. In the variable valve lift structure, two intake cam profiles, low lift and high lift, are set on the camshaft, an exhaust cam profile is set, a low-lift intake rocker arm, a high-lift intake rocker arm and an exhaust rocker arm are set. When the engine is operating at high speed, the low-lift intake rocker arm and the high-lift intake rocker arm are connected together by a pin shaft to achieve high-lift movement of the valve.

[0004] Another Chinese patent document CN104251146B discloses an engine, wherein a first rocker arm is supported by a rocker arm shaft and is configured to enable a valve to be actuated. A second rocker arm is configured by a rocker arm shaft to be parallel to the first rocker arm in the axial direction of the camshaft. A switching pin component is movable in the axial direction of the camshaft, and in a first position, connects the first rocker arm and the second rocker arm, and rocking together with the first rocker arm and the second rocker arm. When viewed from the axial direction of the camshaft, the switching pin component is located at the end side of the valve relative to the rocker arm shaft.

[0005] In the above patent documents, when switching the valve lift requirements between low speed and high speed, it is achieved by connecting or disconnecting the two rocker arms. When the two rocker arms are connected as one, the moment of inertia is large when working at high speed, requiring a larger valve spring force and rocker arm torsion spring force, resulting in a large power consumption of the variable valve lift structure itself, which means that the engine valve train itself consumes more power, reducing the power performance of the engine. Summary of the invention

[0006] In order to solve the technical problem of large power consumption of the variable lift valve structure in the prior art, the present invention provides an engine variable lift valve device, including a cam assembly, a valve rocker arm, a high lift rocker arm and a low lift rocker arm; the valve rocker arm is provided with a movable linkage pin; wherein: when the linkage pin exits from under the high lift rocker arm, the low lift rocker arm drives the valve rocker arm to swing, and the high lift rocker arm swings idle; when the linkage pin enters under the high lift rocker arm, the high lift rocker arm presses against the linkage pin to drive the valve rocker arm to swing, and the low lift rocker arm swings idle.

[0007] In this scheme, during the operation of the cam assembly, when the high-lift action is performed, the linkage pin enters under the high-lift rocker arm, and the high-lift rocker arm swings to resist the linkage pin and drive the valve rocker arm to swing. At this time, the low-lift rocker arm swings in vain and does not contact the valve rocker arm, so the rotational inertia of the low-lift rocker arm will not be applied to the valve; when the low-lift action is performed, since the linkage pin withdraws from under the high-lift rocker arm, after the high-lift rocker arm and the low-lift rocker arm swing, the valve rocker arm is driven to swing by the low-lift rocker arm, and the high-lift rocker arm will not contact the linkage pin, and will not contact the valve rocker arm, and the high-lift rocker arm swings in vain, so the rotational inertia of the high-lift rocker arm will not be applied to the valve.

[0008] Therefore, compared with the prior art, in the present invention, the contact state of the high-lift rocker arm and the low-lift rocker arm with the valve rocker arm is changed by the movement of the linkage pin. Under high-speed or low-speed conditions, only the rotational inertia of one lift rocker arm will be applied to the valve. Especially under high-speed conditions, only the rotational inertia of the high-lift rocker arm will be applied to the valve, which can reduce the design force value of the valve spring and the power consumption of the variable valve lift rocker arm structure itself, thereby improving the engine performance to a greater extent.

[0009] Preferably, a swing portion is provided at one end of the low-lift rocker arm and the high-lift rocker arm facing the valve rocker arm. When the linkage pin exits from below the swing portion of the high-lift rocker arm, the swing portion of the high-lift rocker arm does not contact the valve rocker arm, while the swing portion of the low-lift rocker arm contacts the valve rocker arm. When the linkage pin enters the swing portion below the high-lift rocker arm, the swing portion of the high-lift rocker arm contacts the valve rocker arm, while the swing portion of the low-lift rocker arm in the non-base circle section of the cam assembly does not contact the valve rocker arm. In this solution, the high-lift and low-lift motions of the valve are switched by the cooperation of the swing portions on the high-lift rocker arm and the low-lift rocker arm with the linkage pin, and the structure is simple.

[0010] Preferably, the valve rocker arm is provided with a linkage pin hole for installing a linkage pin, and a return spring is disposed on the linkage pin outer sleeve. In this solution, after the return spring is disposed in the linkage pin hole, when the linkage pin is subjected to an external force, the linkage pin enters under the high-lift rocker arm, and when the external force is removed, the linkage pin exits under the high-lift rocker arm under the action of the return spring, and the structure is simple.

[0011] Preferably, a stop collar is provided in the linkage pin hole to limit the movement of the linkage pin. In this solution, the setting of the stop collar can prevent the linkage pin from coming out of the linkage pin hole, thereby ensuring the normal movement of the valve height and lift.

[0012] Preferably, it also includes a rocker arm mandrel, the valve rocker arm is provided with a rocker arm sleeve, the high lift rocker arm is sleeved on the low lift rocker arm, the low lift rocker arm is sleeved on the rocker arm sleeve, and the low lift rocker arm, the high lift rocker arm and the valve rocker arm swing around the rocker arm mandrel axis independently. In this solution, the arrangement of the rocker arm sleeve facilitates the arrangement of the low lift rocker arm and the high lift rocker arm on the valve rocker arm, and can also ensure the independent swing of the high lift rocker arm and the low lift rocker arm, and the structure is simple.

[0013] Preferably, a clearance portion is provided on the rocker arm sleeve. In this solution, the provision of the clearance portion can shorten the space occupied by the two lift rocker arms on the rocker arm sleeve, making the structure compact.

[0014] Preferably, rocker arm torsion springs are provided inside the low-lift rocker arm and the high-lift rocker arm, and one rocker arm torsion spring is embedded in the other rocker arm torsion spring. In this solution, the provision of the rocker arm torsion springs can make the low-lift rocker arm and the high-lift rocker arm always counteract the cam assembly, ensuring that the movement of the cam assembly can normally drive the movement of the high-lift rocker arm and the low-lift rocker arm, and the structure is simple.

[0015] Preferably, a torsion spring fixing sleeve is provided at the end of the rocker arm sleeve, a limiting portion corresponding to one end of the two rocker arm torsion springs is provided on the torsion spring fixing sleeve, and a mounting portion corresponding to the other end of the rocker arm torsion spring is provided on both the low-lift rocker arm and the high-lift rocker arm. This solution realizes the installation of the two rocker arm torsion springs on the rocker arm sleeve and the high-lift rocker arm and the low-lift rocker arm, has a simple structure, and the torsion spring fixing sleeve can also prevent the rocker arm torsion spring from falling off.

[0016] Preferably, a clearance zone of the rocker arm torsion spring is provided on the high lift rocker arm or low lift rocker arm near the torsion spring fixing sleeve. The setting of the clearance zone in this solution can ensure that the rocker arm torsion spring does not interfere with the high lift rocker arm or low lift rocker arm when twisting.

[0017] Preferably, the torsion spring fixing sleeve is provided with a flat surface. In this solution, the provision of the flat surface can prevent the torsion spring fixing sleeve from rotating.

[0018] Preferably, the torsion spring fixing sleeve is also provided with a back-stop washer. In this solution, the provision of the back-stop washer can prevent the rocker arm torsion spring from backing out of the torsion spring fixing sleeve.

[0019] In a second aspect, the present invention provides a motorcycle engine, including a cylinder head, which also includes the engine variable lift valve device as described above.

[0020] The present invention has the following beneficial effects: 1. The present invention changes the contact state between the high-lift rocker arm and the low-lift rocker arm and the valve rocker arm through the movement of the linkage pin. Under high-speed or low-speed conditions, only one lift rocker arm's rotational inertia is applied to the valve, that is, under low-speed conditions, only the low-lift rocker arm's rotational inertia is applied to the valve, and under high-speed conditions, only the high-lift rocker arm's rotational inertia is applied to the valve. Compared with the variable valve lift rocker arm structure of the prior art, under high-speed conditions, the inertia applied to the valve spring can be reduced, the valve spring design force value can be reduced, the power consumption of the variable valve lift rocker arm mechanism itself can be reduced, and the engine power performance can be improved to a greater extent.

[0021] 2. The present invention has the characteristics of light weight and compact size, can reduce the weight and volume of the engine, and is suitable for engines using variable valve lift technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a partial schematic diagram of an engine in an embodiment of an engine variable lift valve device and a motorcycle engine of the present invention; Figure 2 It is a schematic diagram of a variable lift valve device embodiment 1 of an engine; Figure 3 It is a schematic diagram of the cylinder head structure; Figure 4 for Figure 2 Exploded view of the variable valve lift rocker arm assembly; Figure 5 Schematic diagram of the valve rocker arm structure; Figure 6 It is a schematic diagram of the low lift rocker arm structure; Figure 7 It is a schematic diagram of the high lift rocker arm structure; Figure 8 It is a schematic diagram of the structure of the torsion spring fixing sleeve; Fig. 9 It is a schematic diagram of the low lift rocker arm assembly; Fig.10 It is a schematic diagram of a high lift rocker arm assembly; Fig.11 It is a schematic diagram of the structure of the variable valve lift rocker arm assembly; Fig.12 It is a structural schematic diagram of the variable valve lift rocker arm assembly in a low lift working state; Fig.13 It is a structural schematic diagram of a variable valve lift rocker arm assembly in a high lift working state; Fig.14 It is a schematic diagram of the lift height difference between low valve lift and high valve lift; Fig.15 is a cross-sectional view of a variable valve lift rocker arm assembly; Fig.16 It is a structural schematic diagram of a variable valve lift rocker arm assembly embodiment 2; Fig.17 It is an axonometric view of a variable valve lift rocker arm assembly embodiment 2; Fig.18 It is a schematic diagram of the structure of the low-lift rocker arm 3 in Example 2. DETAILED DESCRIPTION

[0023] The following is further described in detail through specific implementation methods: The reference numerals in the drawings of the specification include: camshaft 1, low lift intake cam 1-1, high lift intake cam 1-2, valve rocker arm 2, valve rocker arm body 2-1, rocker arm sleeve 2-2, linkage pin 2-3, return spring 2-4, stop collar 2-5, valve adjustment screw 2-6, low lift rocker arm 3, low lift rocker arm body 3-1, roller bearing 3-2, low lift rocker arm sleeve 3-3, high lift rocker arm 4, rocker arm slide plate 4-1, rocker arm bow 4-2, third rocking part 4-3, solenoid valve push rod 5, solenoid valve 6, valve 7, rectangular torsion spring 8, first end portion 8-1 of rectangular torsion spring, The second end 8-2 of the rectangular torsion spring, the circular torsion spring 9, the first end 9-1 of the circular torsion spring, the second end 9-2 of the circular torsion spring, the torsion spring fixing sleeve 10, the first slot 10-1, the second slot 10-2, the stop washer 11, the cylinder head 12, the low-lift intake rocker arm assembly 14, the high-lift intake rocker arm assembly 15, the rocker arm assembly 16, the rocker arm core shaft 17, the yielding part a, the first swinging part b, the linkage pin hole c, the first oil hole d, the second oil hole e, the rectangular torsion spring slot f, the second swinging part g, the third oil hole h, the circular torsion spring mounting hole j, the first conical protrusion n, the second conical protrusion m, and the yielding area t.

[0024] The embodiment is basically as shown in the attached Figure 1 As shown: an engine variable lift valve device, including a cam assembly and a rocker arm assembly 16, the rocker arm assembly 16 includes a valve rocker arm 2, a high lift rocker arm 4 and a low lift rocker arm 3, the cam assembly and the valve rocker arm 2 are located on different sides of the rocker arm assembly 16. The valve rocker arm 2 is provided with a movable linkage pin 2-3; wherein: when the linkage pin 2-3 exits from the bottom of the high lift rocker arm 4, the low lift rocker arm 3 drives the valve rocker arm 2 to swing, and the high lift rocker arm 4 swings in vain; when the linkage pin 2-3 enters the bottom of the high lift rocker arm 4, the high lift rocker arm 4 presses against the linkage pin 2-3 to drive the valve rocker arm 2 to swing, and the low lift rocker arm 3 swings in vain.

[0025] This embodiment also discloses a motorcycle engine, including a cylinder head and the above-mentioned engine variable lift valve device.

[0026] Example 1 like Figure 1 to Figure 15As shown, an engine variable lift valve device includes a camshaft 1, a valve rocker arm 2, a low lift rocker arm 3, a high lift rocker arm 4, a solenoid valve push rod 5, a solenoid valve 6, two rocker arm torsion springs, a torsion spring fixing sleeve 10, a backstop washer 11, an exhaust rocker arm 13 and a rocker arm core shaft 17, wherein the two rocker arm torsion springs are a rectangular torsion spring 8 and a circular torsion spring 9. The valve rocker arm 2, the low-lift rocker arm 3, the high-lift rocker arm 4, the rectangular torsion spring 8, the circular torsion spring 9, the torsion spring fixing sleeve 10 and the back-stop washer 11 are assembled on the cylinder head 12 of the motorcycle engine through the rocker arm core shaft 17; the valve rocker arm 2 contacts the intake valve 7 through the valve adjusting screw 2-6; the low-lift rocker arm 3 contacts the low-lift intake cam 1-2 through the roller 3-2; the high-lift rocker arm 4 contacts the high-lift intake cam 1-1 through the rocker arm slide plate 4-1; the valve rocker arm 2 and the low-lift rocker arm 3 form a complete low-lift intake rocker arm assembly 14; the valve rocker arm 2 and the high-lift rocker arm 4 form a complete high-lift intake rocker arm assembly 15.

[0027] like Figure 5 As shown, the valve rocker arm 2 includes a valve rocker arm body 2-1 and a rocker arm sleeve 2-2. The valve rocker arm 2 is also provided with a linkage pin hole c, a linkage pin 2-3, a return spring 2-4, a stop collar 2-5 and a rocker arm sleeve 2-2, wherein the stop collar 2-5 is an elastic retaining ring. The end of the linkage pin 2-3 is provided with a first conical protrusion n. The rocker arm sleeve 2-2 and the valve rocker arm body 2-1 are split. The rocker arm sleeve 2-2 is pressed onto the rocker arm body 2-1, and there is no relative sliding between the two. The rocker arm sleeve 2-2 is provided with a first oil hole d for lubrication. The valve rocker arm body 2-1 is provided with a yielding portion a. The yielding portion a is used in conjunction with the yielding sink height h3 of the low-lift rocker arm 3 to shorten the size of the rocker arm assembly 16 along the axis direction of the rocker arm core shaft 17, making the structure compact. The valve rocker arm body 2-1 is provided with a first rocking portion b, which is formed by fine machining. The valve rocker arm body 2-1 is also provided with a linkage pin hole c.

[0028] like Figure 6 As shown, the low-lift rocker arm 3 includes a low-lift rocker arm body 3-1 and a roller bearing 3-2. The low-lift rocker arm body 3-1 is provided with a low-lift rocker arm sleeve 3-3. The low-lift rocker arm sleeve 3-3 and the low-lift rocker arm body 3-1 are integrated. The low-lift rocker arm sleeve 3-3 is provided with a rectangular torsion spring groove f and a second oil hole e for lubrication; the low-lift rocker arm body 3-1 is provided with a second rocking portion g, and the second rocking portion g is formed by fine machining.

[0029] like Figure 7As shown, the high lift rocker arm 4 is provided with a rocker arm slide plate 4-1, a rocker arm bow 4-2, a third rocking portion 4-3, a third oil hole h and a circular torsion spring mounting hole j, and the rocker arm slide plate 4-1 is arc-shaped. The high lift rocker arm 4 is sleeved on the low lift rocker arm sleeve 3-3, and the inner hole of the high lift rocker arm 4 is provided with a clearance area t, so that the rectangular torsion spring 8 on the low lift rocker arm 3 will not interfere with the high lift rocker arm 4 when twisting.

[0030] like Figure 4 and Figure 8 As shown, the torsion spring fixing sleeve 10 is provided with a first clamping groove 10-1 and a second clamping groove 10-2, the second end 8-2 of the rectangular torsion spring 8 is clamped into the first clamping groove 10-1, and the second end 9-2 of the circular torsion spring 9 is clamped into the second clamping groove 10-2. The torsion spring fixing sleeve 10 is cylindrical, and the inner cavity diameter of the torsion spring fixing sleeve 10 is larger than the diameter of the circular torsion spring 9, and can accommodate the rectangular torsion spring 8 and the circular torsion spring 9. The outer periphery of the torsion spring fixing sleeve 10 is provided with a first flat surface r, a second flat surface s and a third flat surface q, and the third flat surface q cooperates with the anti-rotation surface 12-1 of the cylinder head 12 to prevent the torsion spring fixing sleeve 10 from rotating around the rocker arm core shaft 17. The anti-retraction washer 11 is assembled on the side of the clamping groove 10-1 and the clamping groove 10-2 of the torsion spring fixing sleeve 10, which can prevent the rectangular torsion spring 8 and the circular torsion spring 9 from exiting the clamping groove 10-1 and the clamping groove 10-2.

[0031] like Figure 4 and Fig.11As shown, the assembly relationship between the low-lift rocker arm 3 and the high-lift rocker arm 4 is as follows: the low-lift rocker arm 3 is inserted into the rocker arm sleeve 2-2 of the valve rocker arm 2 through the inner hole of the low-lift rocker arm sleeve 3-3, and the two are clearance-matched, and the low-lift rocker arm 3 can flexibly rotate around the rocker arm sleeve 2-2; the high-lift rocker arm 4 is inserted into the low-lift rocker arm sleeve 3-3, and the two are clearance-matched, and the high-lift rocker arm 4 can flexibly rotate around the low-lift rocker arm sleeve 3-3; the rectangular torsion spring 8 and the circular torsion spring 9 are installed in the torsion spring fixing The cylindrical inner cavity of the sleeve 10, the second end 8-2 of the rectangular torsion spring 8 is inserted into the slot 10-1 of the torsion spring fixing sleeve 10, the second end 9-2 of the circular torsion spring 9 is inserted into the slot 10-2, the first end 8-1 of the rectangular torsion spring 8 is inserted into the rectangular torsion spring slot f of the low lift rocker arm 3, the first end 9-1 of the circular torsion spring 9 is installed into the circular torsion spring installation hole j of the high lift rocker arm 4, and the stop washer 11 is installed on the side of the slot 10-1 and the slot 10-2 of the torsion spring fixing sleeve 10. The assembled rocker arm assembly 16 is assembled to the cylinder head 12 of the engine through the rocker arm mandrel 17. During the assembly process, when the camshaft 1 is installed into the cylinder head 12, the low-lift rocker arm 3 and the high-lift rocker arm 4 need to be lifted to a certain height. When lifted, the rectangular torsion spring 8 and the circular torsion spring 9 will be driven to rotate a certain angle around the axis of the rocker arm core shaft 17. The torsion spring fixing sleeve 10 is pressed against the anti-rotation surface 12-1 on the cylinder head 12 through the third flat surface q, which can prevent the torsion spring fixing sleeve 10 from twisting along the axis of the rocker arm core shaft 17. The rectangular torsion spring 8 and the circular torsion spring 9 will generate torque when twisting. The roller bearing 3-2 of the low-lift rocker arm 3 and the rocker arm slide plate 4-1 of the high-lift rocker arm 4 are tightly pressed against the low-lift intake cam 1-2 and the high-lift intake cam 1-1 respectively under the action of the rectangular torsion spring 8 and the circular torsion spring 9. Figure 2 shown.

[0032] The specific implementation process is as follows: When the engine speed is in the low speed area, such as Figure 2 to Figure 15 As shown, the solenoid valve 6 does not work, and the linkage pin 2-3 on the valve rocker arm 2 retreats to the direction of the solenoid valve push rod 5 under the force of the return spring 2-4. The linkage pin 2-3 has no contact relationship with the third rocking portion 4-3 of the high-lift rocker arm 4. When the camshaft 1 rotates, the low-lift intake cam 1-2 drives the low-lift rocker arm 3 to contact the first rocking portion b on the valve rocker arm 2 through the second rocking portion g, so that the valve rocker arm 2 swings around the axis of the cam core shaft 17, as shown in FIG. Fig.12 As shown, the valve adjusting screw 2-6 contacts the valve 7 to move the valve 7. At this time, the low-lift intake rocker arm 3 and the valve rocker arm 2 form a complete low-lift intake rocker arm assembly 14 to drive the valve 7 to perform low-lift movement.

[0033] In the low speed range of the engine, the high lift intake cam 1-1 on the camshaft 1 causes the high lift rocker arm 4 to swing through the rocker arm slide plate 4-1. Since the third rocking portion 4-3 does not contact the linkage pin 2-3, as shown in FIG. Fig.12 As shown, the high-lift rocker arm 4 swings in vain, that is, it does not participate in driving the valve 7. At this time, the vain swing cannot allow the rocker arm slide plate 4-1 to separate from the high-lift intake cam 1-1. Therefore, the function of the circular torsion spring 9 is to press the high-lift rocker arm 4 tightly against the high-lift intake cam 1-1 without flying off.

[0034] When the engine speed is in the high-speed area, the solenoid valve 6 works, and the solenoid valve 6 will push the solenoid valve push rod 5 to make the linkage pin 2-3 move axially toward the high-lift rocker arm 4, and the linkage pin 2-3 is pushed to the bottom of the third rocking portion 4-3 of the high-lift rocker arm 4 and remains stationary. When the camshaft 1 rotates, the low-lift intake cam 1-2 and the high-lift intake cam 1-1 will drive the low-lift rocker arm 3 and the high-lift rocker arm 4 to swing. Since the lift of the high-lift intake cam 1-1 is higher than that of the low-lift cam 1-2, and the lift and wrap angle of the high-lift cam 1-1 are greater than those of the low-lift cam 1-2, that is, when the camshaft 1 rotates to a certain angle, the high-lift rocker arm 4 will swing larger than the low-lift rocker arm 3, and the third rocking portion 4-3 on the high-lift rocker arm 4 will contact the linkage pin 2-3 first. Fig.13 As shown, the second rocking portion g on the low lift rocker arm 3 is separated from the first rocking portion b of the valve rocker arm 2, and the separation distance is determined by the height difference between the low and high valve lifts, such as Fig.13 At this time, the high lift rocker arm 4 and the valve rocker arm 2 form a complete high lift intake rocker arm assembly 15 to drive the valve 7 to perform high lift motion. Similarly, the low lift rocker arm 3 also needs to use a rectangular torsion spring 8 when it is swinging in the air to prevent it from flying off.

[0035] like Fig.15 As shown, when the engine speed is in the low-speed area, after the linkage pin 2-3 retreats under the action of the return spring 2-4, the small end face of the second conical convex portion m of the linkage pin 2-3 passes over the side of the high-lift rocker arm 4 and is located below the third rocking portion 4-3 of the high-lift rocker arm 4, and the second conical convex portion m and the third rocking portion 4-3 of the high-lift rocker arm 4 have an overlapping area; the third rocking portion 4-3 of the high-lift rocker arm 4 is arc-shaped, and the arc diameter is larger than the diameter of the linkage pin 2-3, and the center line of the arc is colinear with the linkage pin hole c. When the low-lift rocker arm 3 and the high-lift rocker arm 4 are on the base circle of the camshaft 1, the linkage pin 2-3 can flexibly penetrate into or exit from below the third rocking portion 4-3 of the high-lift rocker arm 4.

[0036] Example 2 like Figure 16 to Figure 18As shown, the difference from the embodiment 1 is that in this embodiment, the second swinging portion g of the low lift rocker arm 3 is changed from a flat shape to an arc shape, and when the solenoid valve 6 is not working, the linkage pin 2-3 always makes the second swinging portion g of the low lift rocker arm 3 always in contact with the linkage pin 2-3 at the initial position, and the low lift intake cam 1-2 drives the low lift intake rocker arm assembly 14 to push the valve 7 to perform low lift movement in the low speed range of the engine. When the engine is in the high speed range, the solenoid valve 6 pushes the solenoid valve push rod 5 to move the linkage pin 2-3 along its axial direction, so that the linkage pin 2-3 enters below the third swinging portion 4-3 on the high lift rocker arm 4, so that the third swinging portion 4-3 of the high lift rocker arm 4 contacts the linkage pin 2-3. The lift and wrap angle of the high-lift intake cam 1-1 are greater than those of the low-lift intake cam 1-2, and the second rocking portion g on the low-lift rocker arm 3 is separated from the linkage pin 2-3. At this time, the high-lift intake cam 1-1 on the camshaft 1 drives the high-lift intake rocker arm assembly 15 to push the valve 7 to perform high-lift motion.

[0037] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. An engine variable lift valve device, comprising a cam assembly, a valve rocker arm, a high lift rocker arm and a low lift rocker arm; the valve rocker arm is provided with a movable linkage pin; characterized in that: When the linkage pin exits from under the high-lift rocker arm, the low-lift rocker arm drives the valve rocker arm to swing, and the high-lift rocker arm swings idle; when the linkage pin enters under the high-lift rocker arm, the high-lift rocker arm presses against the linkage pin to drive the valve rocker arm to swing, and the low-lift rocker arm swings idle.

2. The engine variable lift valve device according to claim 1, characterized in that: The low-lift rocker arm and the high-lift rocker arm are provided with a rocking portion at one end facing the valve rocker arm. When the linkage pin withdraws from under the high-lift rocker arm, the rocking portion of the high-lift rocker arm does not contact the valve rocker arm, and the rocking portion of the low-lift rocker arm contacts the valve rocker arm; when the linkage pin enters under the high-lift rocker arm, the rocking portion of the high-lift rocker arm contacts the valve rocker arm, and the rocking portion of the low-lift rocker arm does not contact the valve rocker arm in the non-base circle section of the cam assembly.

3. The engine variable lift valve device according to claim 2, characterized in that: The valve rocker arm is provided with a linkage pin hole for installing the linkage pin, and the linkage pin is covered with a return spring.

4. The engine variable lift valve device according to claim 3, characterized in that: A stop collar for limiting the movement of the linkage pin is arranged in the linkage pin hole.

5. The engine variable lift valve device according to any one of claims 1 to 4, characterized in that: It also includes a rocker arm core shaft, the valve rocker arm is provided with a rocker arm sleeve, the high-lift rocker arm is sleeved on the low-lift rocker arm, the low-lift rocker arm is sleeved on the rocker arm sleeve, and the low-lift rocker arm, high-lift rocker arm and valve rocker arm swing around the rocker arm core shaft axis independently.

6. The engine variable lift valve device according to claim 5, characterized in that: The rocker arm shaft sleeve is provided with a yielding portion.

7. The engine variable lift valve device according to claim 6, characterized in that: The low-lift rocker arm and the high-lift rocker arm are both provided with rocker arm torsion springs, wherein one rocker arm torsion spring is embedded in the other rocker arm torsion spring.

8. The engine variable lift valve device according to claim 7, characterized in that: A torsion spring fixing sleeve is provided at the end of the rocker arm sleeve, and a limiting portion corresponding to one end of two rocker arm torsion springs is provided on the torsion spring fixing sleeve. The low-lift rocker arm and the high-lift rocker arm are both provided with a mounting portion corresponding to the other end of the rocker arm torsion spring.

9. The engine variable lift valve device according to claim 8, characterized in that: A yield area of ​​the rocker arm torsion spring is provided on the high-lift rocker arm or the low-lift rocker arm close to the torsion spring fixing sleeve.

10. The engine variable lift valve device according to claim 8, characterized in that: The torsion spring fixing sleeve is provided with a flat surface.

11. The engine variable lift valve device according to claim 10, characterized in that: The torsion spring fixing sleeve is also provided with a back-stop washer.

12. A motorcycle engine, comprising a cylinder head, characterized in that: It also includes an engine variable lift valve device as described in any one of claims 1-11.

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