Variable valve apparatus for air-driven engine

Abstract

The variable valve device of the air-driven engine comprises a rocker arm, a cam shaft and a roller switching device, the rocker arm is provided with a rocker roller, the rocker roller can be switched from one cam to another on the roller shaft, the switching device of the rocker roller adopts an air-driven driving cylinder, the driving cylinder adopts parallel arranged double driving cylinders and coaxially arranged double driving cylinders, and the adjacent cylinders are used as spring seats of return springs, and a return spring is shared with the adjacent driving cylinders, the roller switching device of the variable valve device has a lower height, a more compact structure and fewer parts, can be used in small displacement engines, is suitable for wide application and has low cost.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a variable valve device for an air-driven engine. Background Technology

[0002] There are various known variable valve timing technologies for engines. These technologies achieve variable valve lift or valve timing through different structural designs and control methods, so as to enable the engine to obtain better performance or achieve special functions. One known type of variable valve timing technology uses a sliding rocker arm roller structure. The rocker arm roller is driven by a drive device to switch between two different cams, which can enable the engine to obtain two different valve lifts to improve engine performance or achieve a certain special function such as engine braking.

[0003] Chinese patent CN110080849A discloses a camshaft and valve drive device for an engine. According to the application document disclosed in this patent, the camshaft of this device has two adjacent cams for the rocker arm. The actuator pushes the rocker arm roller to switch from one cam to another through a slot to realize variable valve. This device uses a drive cylinder to drive the rocker arm roller for switching. In addition, CN111878188A also discloses a drive device for driving the rocker arm roller to switch positions, which also uses a drive cylinder to switch the position of the rocker arm roller.

[0004] However, in practical applications, the valve chamber space of an engine is very limited, the cylinder center distance between two cylinders is small, and the arrangement of roller-driven cylinders is difficult. In the disclosed technologies, the structure of the drive cylinder is still not compact enough. Especially for small and medium-sized engines, it is often impossible to arrange drive cylinders for intake and exhaust rocker arms at the same time, which limits the application of this variable valve device. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a variable valve device for an air-driven engine.

[0006] A variable valve timing device for a pneumatically driven engine includes a rocker arm, a camshaft, and a roller switching mechanism. The rocker arm has a rocker arm roller, which is rotatably mounted on a roller shaft. The rocker arm has a widened roller mounting space, and the rocker arm roller can slide left and right on the roller shaft, thus having first and second working positions. The camshaft has adjacent first and second cams. The position of the first cam corresponds to the first working position of the rocker arm roller, and the position of the second cam corresponds to the second working position of the rocker arm roller. Corresponding to the position, the rocker arm is driven by either the first cam or the second cam depending on the working position of the rocker arm roller. The roller switching device includes a drive cylinder and a return spring. The drive cylinder includes a cylinder body, a drive piston, a roller slot, and a guide rod. The roller slot is installed on the piston rod of the drive piston. The lower end of the roller slot is U-shaped and is locked onto the rocker arm roller. A guide hole is provided in the roller slot. The guide rod passes through the guide hole and is installed on the cylinder body. The return spring is coaxially installed on the drive cylinder with the drive piston.

[0007] Furthermore, the driving cylinder includes a dual-drive cylinder and a single-drive cylinder. The cylinder body of the dual-drive cylinder has two cylinder bores with parallel axes. Driving pistons are installed in the two cylinder bores of the cylinder body, and roller slots are installed on the piston rods of the two pistons. The two roller slots respectively engage with the rocker arm rollers of adjacent cylinders in the engine. The driving directions of the two driving pistons are opposite. The dual-drive cylinder is installed between the rocker arms of adjacent cylinders in the engine. The cylinder body of the single-drive cylinder has... There is a cylinder bore, in which a drive piston is installed. A roller groove is installed on the piston rod of the drive piston. The single drive cylinder is installed on the rocker arm side at the front and rear ends of the engine. The roller groove of the single drive cylinder is engaged with the rocker arm roller at the front and rear ends of the engine. The tail ends of the two cylinder bores of the dual drive cylinder are respectively provided with a spring seat hole. The single drive cylinder is provided with a spring seat hole. One end of the return spring is installed on the roller groove of the drive cylinder, and the other end is installed in the spring seat hole of the adjacent drive cylinder.

[0008] Preferably, the driving cylinder includes a dual-drive cylinder and a single-drive cylinder. The cylinder body of the dual-drive cylinder has two cylinder bores arranged coaxially. Driving pistons are installed in the two cylinder bores of the cylinder body, and roller slots are installed on the piston rods of the two pistons. The two roller slots respectively engage with the rocker arm rollers of adjacent cylinders of the engine. The driving directions of the two driving pistons are opposite. The dual-drive cylinder is installed between the rocker arms of adjacent cylinders of the engine. The cylinder body of the single-drive cylinder has a... A cylinder bore is provided, in which a drive piston is installed. A roller groove is installed on the piston rod of the drive piston. The single drive cylinder is installed on the rocker arm side at the front and rear ends of the engine. The roller groove of the single drive cylinder is engaged with the rocker arm rollers at the front and rear ends of the engine. A return spring is installed between the drive cylinders. One end of the return spring is installed on the roller groove of the drive cylinder, and the other end is installed on the roller groove of the adjacent drive cylinder. The drive piston of the drive cylinder shares a return spring with the drive piston of the adjacent cylinder.

[0009] The beneficial effects of the present invention are as follows: Compared with the prior art, the variable valve device for air-driven engines provided by the present invention has a more compact structure for driving cylinders, fewer parts, is more suitable for small displacement engines, has a wider range of applications, and is also cheaper. Attached Figure Description

[0010] The accompanying drawings are provided to better understand the invention and are used together with the following detailed description to describe and explain the invention, but do not constitute a limitation thereof. In the drawings of different embodiments or design schemes in this specification, some parts have the same reference numerals; this only indicates that they are parts that perform the same or similar functions, and does not necessarily mean that they are the same part or have completely identical structures. The specific details should be based on the accompanying drawings and the description in the specification. In the drawings:

[0011] Figure 1 This is a schematic diagram of the structure of the first embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of the rocker arm of the present invention;

[0013] Figure 3 This is a schematic diagram of the roller switching device according to the first embodiment of the present invention;

[0014] Figure 4 This is a schematic diagram of the structure of the dual-drive cylinder according to the first embodiment of the present invention;

[0015] Figure 5 This is a cross-sectional view of the dual-drive cylinder along the center of the two cylinder bores of the first embodiment of the present invention;

[0016] Figure 6 This is a schematic diagram of the roller slot structure according to the first embodiment of the present invention;

[0017] Figure 7 This is a schematic diagram of the structure of the second embodiment of the present invention;

[0018] Figure 8 This is a schematic diagram of the roller switching device according to the second embodiment of the present invention;

[0019] Figure 9 This is a schematic diagram of the structure of the dual-drive cylinder according to the second embodiment of the present invention;

[0020] Figure 10 This is a cross-sectional view of the dual-drive cylinder along the center of the two cylinder bores according to the second embodiment of the present invention; Detailed Implementation

[0021] The specific technical solutions adopted in the embodiments of the present invention will be described in detail and completely below with reference to the accompanying drawings. In the description of the present invention, unless otherwise stated, "multiple" means two or more. The terms "upper", "lower", "front", "rear", "left", "right", etc., used to indicate the orientation or positional relationship are only for the convenience of describing and explaining the orientation or positional relationship of the present invention based on the accompanying drawings. They should not be construed as the specific orientation or positional relationship that the device or element referred to must have, and do not constitute a limitation on the present invention.

[0022] Appendix Figure 1 This diagram shows a structural schematic of the first embodiment of the present invention. For convenience, this embodiment uses a two-cylinder engine as an example. Each cylinder of the engine is provided with an intake rocker arm and an exhaust rocker arm. The variable valve device of the air-driven engine of the present invention includes a rocker arm 1, a camshaft 2, and a roller switching device 3. Figure 2 The structure of rocker arm 1 is shown. Rocker arm 1 has a rocker arm roller 11, which is rotatably mounted on a roller shaft 12. Rocker arm 1 has a widened roller mounting space. Rocker arm roller 11 can slide left and right on the roller shaft, thus giving rocker arm roller two working positions. The camshaft 2 is provided with an adjacent first cam 21 and a second cam 22 for each rocker arm. The position of the first cam 21 corresponds to the first working position of the rocker arm roller 11, and the position of the second cam 22 corresponds to the second working position of the rocker arm roller 11. The rocker arm 1 is driven by the first cam 21 or the second cam 22 depending on the working position of the rocker arm roller 11, thereby enabling the engine to have two valve lifts and realize variable valve.

[0023] Appendix Figure 3A schematic diagram of the roller switching device 3 according to the first embodiment of the present invention is shown. The roller switching device includes a drive cylinder and a return spring 34. The drive cylinder includes a dual drive cylinder 31 and single drive cylinders 32 and 33. The single drive cylinder can drive a single rocker arm roller to switch its working position to one side, and the dual drive cylinder can drive two rocker arm rollers to switch their working positions to the left and right respectively.

[0024] Appendix Figure 4 and appendix Figure 5 A schematic diagram of the structure of a dual-drive cylinder 31 according to a first embodiment of the present invention is shown. The dual-drive cylinder includes a cylinder body 311, a drive piston 312, a roller groove 313, and a guide rod 314. The cylinder body 311 of the dual-drive cylinder 31 has two cylinder holes with parallel axes. A drive piston 312 is installed in each of the two cylinder holes of the cylinder body, and the two drive pistons 312 drive in opposite directions. A roller groove 313 is installed on the piston rod of each of the two drive pistons, as shown in the attached diagram. Figure 6 As shown, the lower end of the roller slot 313 is U-shaped. The dual drive cylinder 31 is installed between the rocker arms of adjacent cylinders of the engine. The two roller slots 313 are respectively engaged with the rocker arm rollers 11 of the adjacent cylinders of the engine (as shown in the attached diagram). Figure 1 As shown, a guide hole 3131 is provided on the roller slot 313, the guide rod 314 passes through the guide hole 3131 and is mounted on the cylinder body, the return spring 34 is coaxially mounted on the drive cylinder with the drive piston 312, and the drive cylinder drives the rocker arm roller 11 to switch between the first working position and the second working position through the roller slot 313 mounted on the piston rod.

[0025] The single-drive cylinders 32 and 33 have the same structure as the left and right halves of the dual-drive cylinders 31, respectively. The cylinder bodies of the single-drive cylinders 32 and 33 are provided with a cylinder bore. The single-drive cylinders 32 and 33 are respectively installed on the rocker arm side at the front and rear ends of the engine. The roller slots of the single-drive cylinders 32 and 33 are respectively engaged on the rocker arm rollers 11 at the front and rear ends of the engine.

[0026] The tail ends of the two cylinder holes on the dual-drive cylinder 31 are respectively provided with a spring seat hole 315. The single-drive cylinders 32 and 33 are provided with spring seat holes 325 and 335. One end of the return spring 34 is installed on the roller slot 313 of the drive cylinder, and the other end is installed in the spring seat hole of the adjacent drive cylinder.

[0027] The single-drive cylinder has one air inlet, and the dual-drive cylinder has two air inlets. The cylinder air inlets are connected to the vehicle's compressed air via pipelines. A solenoid valve is also installed on the pipelines to control the compressed air supply (the pipeline and solenoid valve details are not shown in the attached diagram). The working process of this invention is as follows: When the solenoid valve is not energized, the compressed air supply is closed, the drive cylinder does not work, and the rocker arm roller is in the first working position, driven by the first cam. When the rocker arm roller needs to switch to the second working position, the solenoid valve is energized, compressed air enters the drive cylinder, pushing the drive piston out. The roller slot drives the rocker arm roller to switch to the second working position, where the rocker arm roller is driven by the second cam, thus achieving the switching between two valve lift positions. When the rocker arm roller needs to return to the first working position, the solenoid valve is de-energized, the compressed air in the drive cylinder is released, and the rocker arm roller returns to the first working position under the drive of the return spring. When the rocker arm roller is driven by the cam (the rocker arm roller is in the part of the cam with lift), the rocker arm roller often cannot be pushed by the drive cylinder because the cam exerts a large force on it. Only when the rocker arm roller is in the part where the first cam and the second cam are both base circles, there is no force between the cam and the rocker arm roller, and the rocker arm roller can freely switch between the two working positions. In practical applications, the timing of energizing or de-energizing the solenoid valve can be determined based on the cam phase sensor signal, so that the rocker arm roller starts switching when it just enters the part where the first cam and the second cam are both base circles, thereby ensuring the reliability of the device.

[0028] Appendix Figure 7 A schematic diagram of the structure of the second embodiment of the present invention is shown. For convenience, this embodiment also uses a two-cylinder engine as an example. The difference between this embodiment and the first embodiment lies in the structure of the roller switching device. Figure 8 This diagram shows a schematic representation of the roller switching device 3 according to a second embodiment of the present invention. The roller switching device 3 of this embodiment includes a dual-drive cylinder 31 and single-drive cylinders 32 and 33. Figure 9 and attached Figure 10 The structure of the dual-drive cylinder 31 of this embodiment is shown. The cylinder body 311 of the dual-drive cylinder 31 has two cylinder bores, which are coaxially arranged. Drive pistons 312 are respectively installed in the two cylinder bores of the cylinder body 311. Roller slots 313 are respectively installed on the piston rods of the two drive pistons. The two roller slots are respectively engaged with the rocker arm rollers 11 of the adjacent cylinder of the engine (as shown in the attached figure). Figure 7As shown, the two drive pistons 312 drive in opposite directions. The dual-drive cylinder 31 is installed between the rocker arms of adjacent cylinders in the engine. The single-drive cylinders 32 and 33 have cylinder bores on their cylinder bodies. The single-drive cylinders 32 and 33 are respectively installed on the rocker arm side at the front and rear ends of the engine. The roller slots of the single-drive cylinders 32 and 33 are respectively engaged with the rollers of the rocker arms at the front and rear ends of the engine. A return spring 34 is installed between the drive cylinders. One end of the return spring 34 is installed in the roller slot of the drive cylinder, and the other end is installed in the roller slot of the adjacent drive cylinder. The drive piston of each drive cylinder shares a return spring with the drive piston of the adjacent cylinder. Compared to the first embodiment, this embodiment has fewer parts and lower cost.

[0029] The above embodiment uses a two-cylinder engine as an example. When applied to engines with more cylinders, it is only necessary to increase the number of dual drive cylinders and return springs accordingly.

[0030] Compared with the prior art, the parallel arrangement of dual drive cylinders and the coaxial arrangement of dual drive cylinders adopted in this invention, as well as the use of adjacent cylinders as spring seats for return springs and the sharing of a return spring with adjacent drive cylinders, enable the roller switching device to have a lower height, a more compact structure, and fewer parts, which greatly improves the applicability of this variable valve device and reduces costs.

[0031] It should be noted that the above embodiments are merely preferred embodiments used to illustrate the design scheme and principle of the present invention, and should not be construed as limiting the present invention. For those skilled in the art, further modifications can be made to the technical solutions described in the above embodiments, or some technical features can be replaced or combined, without departing from the concept of the present invention, and all of these should be considered within the scope of protection of the present invention.

Claims

1. A variable valve timing device for a pneumatically driven engine, comprising a rocker arm, a camshaft, and a roller switching mechanism, characterized in that: The rocker arm has a rocker arm roller, which is rotatably mounted on a roller shaft. The rocker arm has a widened roller mounting space, and the rocker arm roller can slide left and right on the roller shaft, thus having first and second working positions. The camshaft has adjacent first and second cams. The position of the first cam corresponds to the first working position of the rocker arm roller, and the position of the second cam corresponds to the second working position of the rocker arm roller. The rocker arm is driven by either the first or second cam depending on the working position of the rocker arm roller. The roller switching device includes a drive cylinder and a return spring. The drive cylinder includes a dual-drive cylinder and a single-drive cylinder. The cylinder body of the dual-drive cylinder has two cylinder holes arranged coaxially. A drive piston is installed in each of the two cylinder holes of the cylinder body. Roller slots are installed on the piston rods of the two pistons, with the lower end of each roller slot being U-shaped, respectively engaging with adjacent cylinders of the engine. The rocker arm roller has a guide hole in the roller slot. A guide rod passes through the guide hole and is installed on the cylinder body. The two drive pistons drive in opposite directions. The dual-drive cylinder is installed between the rocker arms of adjacent cylinders of the engine. The cylinder body of the single-drive cylinder has a cylinder bore. A drive piston is installed in the cylinder bore. A roller slot is installed on the piston rod of the drive piston. The single-drive cylinder is installed on one side of the rocker arm at the front and rear ends of the engine. The roller slot of the single-drive cylinder is engaged with the rocker arm roller at the front and rear ends of the engine. A return spring is installed between the drive cylinders. One end of the return spring is installed on the roller slot of the drive cylinder, and the other end is installed on the roller slot of the adjacent drive cylinder. The drive piston of the drive cylinder shares a return spring with the drive piston of the adjacent cylinder. The return spring is coaxially mounted on the drive cylinder with the drive piston. The drive cylinder has an air inlet. The air inlet is connected to the vehicle's compressed air through a pipeline.

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