Variable valve driving system, engine assembly and vehicle

Abstract

The invention discloses a variable valve driving system, an engine assembly and a vehicle, and belongs to the technical field of engines. According to the variable valve driving system, the engine assembly and the vehicle, the molded line of the first cam is different from the molded line of the second cam, so that when the first driven piece makes contact with the first cam, the second driven piece is separated from the second cam, and when the second driven piece makes contact with the second cam, the first driven piece is separated from the first cam; and abnormal sound caused by back-and-forth switching of the first cam and the second cam is avoided. Meanwhile, when the hydraulic driving unit breaks down or fails, the second driven piece can make contact with the second cam, it is ensured that the engine can work normally, and then the reliability of the engine can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a variable valve drive system, an engine assembly and a vehicle. Background Art

[0002] As the requirements for reducing engine fuel consumption and emissions become increasingly stringent, the Miller cycle is realized through two different valve lifts, thereby achieving different intake volumes at different speeds, thereby improving engine performance, saving fuel, reducing emissions, improving engine power, and reducing the risk of knock in gas engines caused by increased compression ratios.

[0003] However, although the existing variable valve drive system can enable the valve to achieve different lifts, it is prone to frequent cam switching, which may cause abnormal noise and even risk damage, affecting the reliability of the engine. Summary of the invention

[0004] The object of the present invention is to provide a variable valve drive system, an engine assembly and a vehicle, which can avoid abnormal noise caused by frequent switching of cams and improve the reliability of the engine.

[0005] In order to achieve the above objectives, the following technical solutions are provided:

[0006] Variable valve actuation system, including:

[0007] A rocker arm body, wherein a first end of the rocker arm body is provided with a first follower and a second follower, and a second end of the rocker arm body is used to drive the valve to open and close;

[0008] A rocker arm drive mechanism comprises a drive shaft, and a first cam and a second cam both fixedly mounted on the drive shaft, wherein the axis of the first cam and the axis of the second cam both coincide with the axis of the drive shaft, and the profile of the first cam is different from the profile of the second cam; the profile is a curve representing the corresponding relationship between the cam angle and the valve lift;

[0009] A switching mechanism comprises a hydraulic drive unit and an elastic member, wherein a driving end of the hydraulic drive unit is connected to the first follower to drive the first follower to extend to a first circulation position along a first direction through hydraulic pressure, so that the first follower contacts the first cam and the second follower is separated from the second cam, thereby making the lift of the valve a first lift H; the elastic member is configured to make the first follower always have a movement tendency to retract to a second circulation position along the first direction, and when the first follower is located at the second circulation position, the first follower is separated from the first cam, and the second follower is in contact with the second cam, thereby making the lift of the valve a second lift h, and h is not equal to H.

[0010] As a preferred technical solution of the above variable valve drive system, the hydraulic drive unit includes:

[0011] A hydraulic chamber, wherein the hydraulic chamber is disposed in the rocker arm body;

[0012] A piston, wherein the first end of the piston is slidably disposed in the hydraulic cavity along the first direction, and the second end of the piston is located outside the hydraulic cavity and connected to the second follower; one end of the elastic member is connected to the rocker arm body, and the other end is connected to the second end of the piston.

[0013] As a preferred technical solution of the above-mentioned variable valve drive system, the rocker arm body is also provided with a limiting structure, and when the first follower is extended along the first direction to the first circulation position, the limiting structure is used to prevent the first follower from continuing to extend.

[0014] As a preferred technical solution of the above-mentioned variable valve drive system, the rocker arm body is also provided with an elephant foot, and the position of the elephant foot is adjustably arranged on the rocker arm body.

[0015] As a preferred technical solution of the above variable valve drive system, when the first follower is located at the second cycle position, a valve clearance a is provided between the rocker arm body and the valve;

[0016] When the first follower is located at the first cycle position, the rocker arm body is in contact with the valve.

[0017] As a preferred technical solution of the above variable valve drive system, the first follower includes a first roller, which is rotatably disposed on the rocker arm body, and the second follower includes a second roller, which is rotatably disposed on the driving end of the hydraulic drive unit, and the radius of the first roller is equal to the radius of the second roller;

[0018] When the first roller is located at the first circulation position, the distance between the first roller and the axis of the driving shaft is equal to the distance between the second roller and the axis of the driving shaft; the distance between the first circulation position and the second circulation position is b;

[0019] a≤H-h≤b.

[0020] As a preferred technical solution of the above variable valve drive system, the first follower includes a first roller, which is rotatably disposed on the rocker arm body, and the second follower includes a second roller, which is rotatably disposed on the driving end of the hydraulic drive unit, and the radius of the first roller is equal to the radius of the second roller;

[0021] When the first roller is located at the first circulation position, the distance between the first roller and the axis of the driving shaft is smaller than the distance between the second roller and the axis of the driving shaft; the distance between the first circulation position and the second circulation position is b;

[0022] The first roller also has a third position. When the first roller is in the third position, the distance between the first roller and the axis of the drive shaft is equal to the distance between the second roller and the axis of the drive shaft. The distance between the third position and the second circulation position is c.

[0023] ﹣(b-c)≤H-h≤c.

[0024] As a preferred technical solution of the above variable valve drive system, the first follower includes a first roller, which is rotatably disposed on the rocker arm body, and the second follower includes a second roller, which is rotatably disposed on the driving end of the hydraulic drive unit, and the radius r1 of the first roller is greater than the radius r2 of the second roller;

[0025] When the first roller is located at the first circulation position, the distance between the first roller and the axis of the driving shaft is smaller than the distance between the second roller and the axis of the driving shaft; the distance between the first circulation position and the second circulation position is b;

[0026] ﹣(r1-r2)≤H-h≤b-(r1-r2).

[0027] In order to achieve the above purpose, an engine assembly is also provided, including an engine body and a variable valve drive system as described above, wherein the engine body includes a valve that can be opened and closed, and the second end of the rocker arm body is used to drive the valve to open and close.

[0028] In order to achieve the above object, a vehicle is also provided, comprising the engine assembly as described above.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The variable valve drive system, engine assembly and vehicle of the present invention are configured such that the first cam and the second cam have different profiles, so that when the first follower contacts the first cam, the second follower is separated from the second cam, and when the second follower contacts the second cam, the first follower is separated from the first cam, thereby avoiding abnormal noise caused by switching back and forth between the first cam and the second cam. At the same time, when the hydraulic drive unit fails or fails, the second follower can contact the second cam, ensuring that the engine can work normally, thereby improving the reliability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of a variable valve drive system according to an embodiment of the present invention;

[0032] Figure 2 It is a structural schematic diagram of the rocker arm body and the switching mechanism in an embodiment of the present invention;

[0033] Figure 3 It is a structural diagram of the rocker arm driving mechanism in an embodiment of the present invention;

[0034] Figure 4 1 is a valve lift curve diagram of the large Miller cycle and the small Miller cycle in an embodiment of the present invention.

[0035] Reference numerals:

[0036] 1. Rocker arm body; 11. Limiting groove; 13. Elephant foot; 131. Locking nut;

[0037] 211, first roller; 212, first mounting seat; 2121, limiting block;

[0038] 221, second roller; 222, second mounting seat;

[0039] 31. driving shaft; 32. first cam; 33. second cam;

[0040] 41. Piston; 42. Elastic member. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0044] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or are the positions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0045] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0048] like Figure 1-4As shown, this embodiment provides a variable valve drive system, including a rocker arm body 1, a rocker arm drive mechanism and a switching mechanism. The first end of the rocker arm body 1 is provided with a first follower and a second follower, and the second end of the rocker arm body 1 is used to drive the valve to open and close; the rocker arm drive mechanism includes a drive shaft 31, and a first cam 32 and a second cam 33 both fixed on the drive shaft 31, the axis of the first cam 32 and the axis of the second cam 33 both coincide with the axis of the drive shaft 31, and the profile of the first cam 32 is different from the profile of the second cam 33; the profile is a curve that represents the corresponding relationship between the cam angle and the valve lift; the switching mechanism includes a hydraulic The driving unit and the elastic member 42, the driving end of the hydraulic driving unit is connected to the first follower to drive the first follower to extend to the first circulation position along the first direction through the hydraulic pressure, so that the first follower contacts the first cam 32, and the second follower is separated from the second cam 33, so that the lift of the valve is the first lift H; the elastic member 42 is configured so that the first follower always has a movement tendency to retract to the second circulation position along the first direction. When the first follower is in the second circulation position, the first follower is separated from the first cam 32, and the second follower is in contact with the second cam 33, so that the lift of the valve is the second lift h, and h is not equal to H.

[0049] The variable valve drive system of this embodiment sets the profile of the first cam 32 to be different from the profile of the second cam 33, so that when the first follower contacts the first cam 32, the second follower is separated from the second cam 33, and when the second follower contacts the second cam 33, the first follower is separated from the first cam 32, thereby avoiding abnormal noise caused by switching back and forth between the first cam 32 and the second cam 33. At the same time, when the hydraulic drive unit fails or fails, the second follower can contact the second cam 33 to ensure that the engine can work normally, thereby improving the reliability of the engine.

[0050] Exemplarily, the elastic member 42 is a spring sheet. Of course, the elastic member 42 may also adopt other spring structures, which are not limited here.

[0051] Optionally, the hydraulic drive unit includes a hydraulic chamber and a piston 41, wherein the hydraulic chamber is disposed in the rocker arm body 1; the first end of the piston 41 is slidably disposed in the hydraulic chamber along a first direction, and the second end of the piston 41 is located outside the hydraulic chamber and connected to the second follower; one end of the elastic member 42 is connected to the rocker arm body 1, and the other end is connected to the second end of the piston 41. With such a configuration, there is no need to provide an additional cylinder, and the problem of leakage of the hydraulic drive unit can be avoided, thereby improving the reliability of the hydraulic drive unit and simplifying the structure of the variable valve drive system.

[0052] Optionally, the rocker arm body 1 is further provided with a limiting structure, and when the first follower extends along the first direction to the first circulation position, the limiting structure is used to prevent the first follower from continuing to extend, thereby improving the contact stability between the first follower and the first cam 32.

[0053] Optionally, a limit block 2121 is provided at the driving end of the hydraulic drive unit, and the limit structure includes a limit groove 11 provided on the rocker arm body 1. When the first follower extends to the first circulation position along the first direction, the limit block 2121 abuts against the limit groove 11 along the first direction. The structure is simple and easy to implement.

[0054] Optionally, the rocker arm body 1 is further provided with an elephant foot 13, and the position of the elephant foot 13 is adjustably arranged on the rocker arm body 1. It should be noted that by adjusting the position of the elephant foot 13, the purpose of adjusting the valve clearance can be achieved.

[0055] When the hydraulic drive unit is not in operation, the first follower can retract to the second circulation position under the elastic force of the elastic member 42, so that the first follower is separated from the first cam 32, and the second follower is in contact with the second cam 33. At this time, the variable valve drive system forms a mechanical structure. In order to ensure the reliability of the engine, a valve clearance can be set between the elephant foot 13 and the valve.

[0056] When the hydraulic drive unit is activated to make the first follower contact with the first cam 32 and the second follower separate from the second cam 33, the variable valve drive system forms a hydraulic structure, which can automatically achieve overload protection without setting the valve clearance, thereby reducing the impact and noise problems caused by the existence of the valve clearance.

[0057] Specifically, one end of the elephant foot 13 is threadedly connected to the rocker body 1, and one end of the elephant foot 13 is provided with a locking nut 131 threadedly connected thereto. After loosening the locking nut 131, the position of the elephant foot 13 can be adjusted by rotating the elephant foot 13; and the elephant foot 13 can be locked with the rocker body 1 by tightening the locking nut 131.

[0058] In this embodiment, when the first follower is located at the second cycle position, a valve clearance a is provided between the rocker arm body 1 and the valve; when the first follower is located at the first cycle position, the rocker arm body 1 is in contact with the valve.

[0059] It should be noted that when the hydraulic drive unit is activated and generates hydraulic pressure to drive the first follower to extend along the first direction to the first circulation position, due to the limiting effect of the limiting structure, the first follower will no longer extend. At this time, under the reaction of the hydraulic pressure, the second end of the rocker arm body 1 will approach the valve so that the elephant foot 13 contacts the valve, thereby eliminating the valve clearance a.

[0060] In this embodiment, the first follower includes a first roller 211, which is rotatably disposed on the rocker arm body 1, and the second follower includes a second roller 221, which is rotatably disposed on the driving end of the hydraulic drive unit. The radius of the first roller 211 is equal to the radius of the second roller 221. Furthermore, through the profile design of the first cam 32 and the profile design of the second cam 33, when the first follower contacts the first cam 32, the second follower is separated from the second cam 33, and when the second follower contacts the second cam 33, the first follower is separated from the first cam 32, which has the effect of reducing costs and facilitating design.

[0061] Furthermore, when the first roller 211 is located at the first circulation position, the spacing between the first roller 211 and the axis of the driving shaft 31 is equal to the spacing between the second roller 221 and the axis of the driving shaft 31, that is, the axis of the first roller 211 coincides with the axis of the second roller 221. At this time, the spacing between the first circulation position and the second circulation position is b; then a≤H-h≤b.

[0062] In this embodiment, when the second roller 221 contacts the second cam 33 and the first follower is separated from the first cam 32, a small Miller cycle can be realized; the valve lift during the small Miller cycle is the second lift h. When the first follower contacts the first cam 32 and the second follower is separated from the second cam 33, a large Miller cycle can be realized; the valve lift during the large Miller cycle is the first lift H.

[0063] Because there is valve clearance a in the small Miller cycle, there is no valve clearance in the large Miller cycle. Figure 4 As shown, the black part is the valve lift curve in the large Miller cycle, and the red part is the actual valve lift curve after subtracting the valve clearance a in the small Miller cycle, that is, at any crankshaft angle, H-h≥a.

[0064] At any crankshaft angle, by limiting H-h≥a, it is possible to avoid the second cam 33 contacting the second roller 221 and generating switching noise during the large Miller cycle.

[0065] At any crankshaft rotation angle, by limiting H-h≤b, it is possible to avoid the first cam 32 contacting the first roller 211 and generating switching noise during the small Miller cycle.

[0066] For example, a=0.3 mm; b=4.5 mm, then 0.3 mm≤H-h≤4.5 mm. This arrangement is convenient for taking into account both the volume of the hydraulic chamber and the strength of the rocker arm body 1.

[0067] It should be noted that by limiting a≤H-h≤b, it is equivalent to limiting the profile of the first cam 32 and the profile of the second cam 33. The relationship between the profile of the first cam 32 and the valve lift during the large Miller cycle and the derivation method are existing technologies, and the relationship between the profile of the second cam 33 and the valve lift during the small Miller cycle and the derivation method are existing technologies, which will not be repeated here.

[0068] In summary, through the above-mentioned profile design of the first cam 32 and the profile design of the second cam 33, the valve clearance is retained in the small Miller cycle, and there is no valve clearance in the large Miller cycle; at the same time, in the large Miller cycle, only the first cam 32 is in contact with the first roller 211, and the second cam 33 is separated from the second roller 221; and in the small Miller cycle, only the second cam 33 is in contact with the second roller 221, and the first cam 32 is separated from the first roller 211, thereby avoiding switching noise.

[0069] Specifically, the first follower includes a first mounting seat 212, the first mounting seat 212 is fixedly mounted on the rocker arm body 1, and the first roller 211 is rotatably connected to the first mounting seat 212. Further, the second follower includes a second mounting seat 222, the second mounting seat 222 is fixedly connected to the second end of the piston 41, and the second roller 221 is rotatably connected to the second mounting seat 222. Further, the limit block 2121 is fixedly mounted on the second mounting seat 222 of the piston 41, so as not to interfere with the piston 41 and the second roller 221.

[0070] In other embodiments, the first follower includes a first roller, which is rotatably disposed on the rocker arm body, and the second follower includes a second roller, which is rotatably disposed on the driving end of the hydraulic drive unit, and the radius of the first roller is equal to the radius of the second roller; when the first roller is located at the first circulation position, the distance between the first roller and the axis of the drive shaft is smaller than the distance between the second roller and the axis of the drive shaft; the distance between the first circulation position and the second circulation position is b; the first roller also has a third position, and when the first roller is located at the third position, the first roller The spacing between the axis of the drive shaft and the spacing between the second roller and the axis of the drive shaft are equal; the spacing between the third position and the second cycle position is c; -(b-c)≤H-h≤c, thereby also achieving the retention of valve clearance during the small Miller cycle and no valve clearance during the large Miller cycle; at the same time, during the large Miller cycle, only the first cam contacts the first roller, and the second cam is separated from the second roller; and during the small Miller cycle, only the second cam contacts the second roller, and the first cam is separated from the first roller, thereby avoiding switching noise.

[0071] Exemplarily, when b=5mm, since the radius of the first roller is equal to the radius of the second roller, c=4.5mm. When the first roller is in the first cycle position, the large Miller cycle works, and the axes of the large Miller roller and the small Miller roller do not coincide, that is, the first roller is closer to the axis of the drive shaft than the second roller. In this case, the valve clearance of the small Miller cycle is increased by 5mm-4.5mm=0.5mm during the large Miller cycle. At this time, in order to avoid interference caused by the contact between the second cam and the second roller during the large Miller cycle, the valve lift during the small Miller cycle can be within 0.5mm greater than the valve lift during the large Miller cycle, that is, h-H≤0.5mm. At the same time, when the first roller is in the second cycle position, the small Miller cycle works, and the spacing between the axis of the first roller and the axis of the second roller along the first direction is converted to the valve side, that is, H-h≤4.5mm. Therefore, -0.5mm≤H-h≤4.5mm.

[0072] In other embodiments, the first follower includes a first roller, which is rotatably disposed on the rocker arm body, and the second follower includes a second roller, which is rotatably disposed on the driving end of the hydraulic drive unit, and the radius r1 of the first roller is greater than the radius r2 of the second roller; when the first roller is located at the first cycle position, the distance between the first roller and the axis of the drive shaft is smaller than the distance between the second roller and the axis of the drive shaft; the distance between the first cycle position and the second cycle position is b; -(r1-r2)≤H-h≤b-(r1-r2), thereby also achieving the retention of valve clearance during the small Miller cycle and the absence of valve clearance during the large Miller cycle; at the same time, during the large Miller cycle, only the first cam contacts the first roller, and the second cam is separated from the second roller; and during the small Miller cycle, only the second cam contacts the second roller, and the first cam is separated from the first roller, thereby avoiding switching noise.

[0073] This embodiment also provides an engine assembly, including an engine body and a variable valve drive system as described above, the engine body includes a valve that can be opened and closed, and the second end of the rocker arm body is used to drive the valve to open and close.

[0074] This embodiment also provides a vehicle, comprising the above-mentioned engine assembly.

[0075] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A variable valve drive system, characterized in that: include: A rocker arm body (1), wherein a first end of the rocker arm body (1) is provided with a first follower and a second follower, and a second end of the rocker arm body (1) is used to drive the valve to open and close; A rocker arm drive mechanism comprises a drive shaft (31), and a first cam (32) and a second cam (33) both fixedly mounted on the drive shaft (31), wherein the axis of the first cam (32) and the axis of the second cam (33) both coincide with the axis of the drive shaft (31), and the profile of the first cam (32) is different from the profile of the second cam (33); the profile is a curve representing the corresponding relationship between the cam angle and the valve lift; A switching mechanism, comprising a hydraulic drive unit and an elastic member (42), wherein a drive end of the hydraulic drive unit is connected to the first follower, so as to drive the first follower to extend to a first circulation position along a first direction through hydraulic pressure, so that the first follower contacts the first cam (32), and the second follower is separated from the second cam (33), thereby making the lift of the valve a first lift H; The elastic member (42) is configured to make the first follower always have a movement tendency to retract along the first direction to a second cycle position. When the first follower is located at the second cycle position, the first follower is separated from the first cam (32), and the second follower is in contact with the second cam (33), thereby making the lift of the valve a second lift h, and h is not equal to H.

2. The variable valve actuation system according to claim 1, characterized in that: The hydraulic drive unit comprises: A hydraulic chamber, the hydraulic chamber being arranged in the rocker arm body (1); A piston (41), wherein the first end of the piston (41) is slidably disposed in the hydraulic cavity along the first direction, and the second end of the piston (41) is located outside the hydraulic cavity and connected to the second follower; one end of the elastic member (42) is connected to the rocker arm body (1), and the other end is connected to the second end of the piston (41).

3. The variable valve actuation system according to claim 1, characterized in that: The rocker arm body (1) is also provided with a limiting structure, and when the first follower extends along the first direction to the first circulation position, the limiting structure is used to prevent the first follower from continuing to extend.

4. The variable valve actuation system according to claim 1, characterized in that: The rocker arm body (1) is also provided with an elephant foot (13), and the position of the elephant foot (13) is adjustable on the rocker arm body (1).

5. The variable valve actuation system according to claim 1, characterized in that: When the first follower is located at the second cycle position, a valve clearance a is provided between the rocker arm body (1) and the valve; When the first follower is located at the first cycle position, the rocker arm body (1) is in contact with the valve.

6. The variable valve actuation system according to claim 5, characterized in that: The first follower comprises a first roller (211), the first roller (211) being rotatably disposed on the rocker arm body (1), the second follower comprises a second roller (221), the second roller (221) being rotatably disposed on a driving end of the hydraulic drive unit, and the radius of the first roller (211) is equal to the radius of the second roller (221); When the first roller (211) is located at the first circulation position, the distance between the first roller (211) and the axis of the driving shaft (31) is equal to the distance between the second roller (221) and the axis of the driving shaft (31); the distance between the first circulation position and the second circulation position is b; a≤H-h≤b.

7. The variable valve actuation system according to claim 1, characterized in that: The first follower comprises a first roller (211), the first roller (211) being rotatably disposed on the rocker arm body (1), the second follower comprises a second roller (221), the second roller (221) being rotatably disposed on a driving end of the hydraulic drive unit, and the radius of the first roller (211) is equal to the radius of the second roller (221); When the first roller (211) is located at the first circulation position, the distance between the first roller (211) and the axis of the driving shaft (31) is smaller than the distance between the second roller (221) and the axis of the driving shaft (31); the distance between the first circulation position and the second circulation position is b; The first roller (211) further has a third position. When the first roller (211) is located at the third position, the distance between the first roller (211) and the axis of the driving shaft (31) is equal to the distance between the second roller (221) and the axis of the driving shaft (31); the distance between the third position and the second circulation position is c; ﹣(b-c)≤H-h≤c.

8. The variable valve actuation system according to claim 1, characterized in that: The first follower comprises a first roller (211), the first roller (211) being rotatably disposed on the rocker arm body (1), the second follower comprises a second roller (221), the second roller (221) being rotatably disposed on a driving end of the hydraulic drive unit, and a radius r1 of the first roller (211) is greater than a radius r2 of the second roller (221); When the first roller (211) is located at the first circulation position, the distance between the first roller (211) and the axis of the driving shaft (31) is smaller than the distance between the second roller (221) and the axis of the driving shaft (31); the distance between the first circulation position and the second circulation position is b; ﹣(r1-r2)≤H-h≤b-(r1-r2).

9. An engine assembly, characterized in that: It comprises an engine body and a variable valve drive system as claimed in any one of claims 1 to 8, wherein the engine body comprises a valve that can be opened and closed, and the second end of the rocker arm body (1) is used to drive the valve to open and close.

10. A vehicle, characterized in that Comprising the engine assembly as claimed in claim 9.

Images