Gas engine and camshaft thereof
By optimizing the model line and valve parameters of the gas engine camshaft based on the diesel engine camshaft, the problem of sharing the gas engine and diesel engine is solved, cost and process advantages are achieved, and mechanical efficiency and exhaust emission efficiency are improved.
Patent Information
- Application Number
- CN202420257757.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-01
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2034-02-01
AI Technical Summary
The existing gas engine camshaft design is difficult to share with the same type of diesel engine, resulting in increased manufacturing costs and complicated processes, and cannot meet the delay angle requirements of intake and exhaust gas.
A gas engine camshaft was designed. By optimizing the intake cam and exhaust cam shapes based on the diesel engine camshaft blank, adjusting the enclosure angle, valve opening angle and valve closing angle to ensure commonality between the gas engine and the diesel engine. and optimize the lift curve of the intake and exhaust valves.
The commonality between gas engine and diesel engine is achieved, the manufacturing cost and process complexity is reduced, the mechanical efficiency is improved, the motion loss is reduced, and the stable speed is maintained under no-load and low load conditions is avoided, and abnormal escape of exhaust gas and Reflow of exhaust gas in the cylinder.
Smart Images
Figure CN222121615U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of engines, and further to a gas engine and a camshaft thereof. Background Art
[0002] The premixed gas engine is developed based on the same type of diesel engine. The amount of working fluid mixture sucked into the cylinder requires the intake valve and the throttle to work together to meet different load requirements. The engine camshaft is an important component of the engine and is used to control the opening and closing of the valve. The timing value and scavenging overlap angle of the engine camshaft are the main factors affecting the performance of the engine. The appropriate timing value and scavenging overlap angle can improve the engine performance. At present, the intake and exhaust scavenging overlap angles are mostly designed to be negative values, that is, the opening of the intake valve is delayed by a certain angle compared to the closing of the exhaust valve. If you pursue the delayed angle of intake and exhaust and unreasonably increase the timing value of intake and exhaust, it may lead to the inability to share the camshaft blank with the same type of diesel engine, and a new camshaft blank needs to be made. Utility Model Content
[0003] In view of the above technical problems, the purpose of the utility model is to provide a gas engine and a camshaft thereof. The camshaft can be developed based on the camshaft blank of the same type of diesel engine, so that the gas engine and the diesel engine have commonality. Since the manufacturing cost is almost unchanged, it has strong cost and process advantages for mass production.
[0004] In order to achieve the above object, the utility model provides a gas engine camshaft, comprising an intake cam and an exhaust cam, wherein the profile of the intake cam comprises a first base circle and a first cam lobe, and the profile of the exhaust cam comprises a second base circle and a second cam lobe, and is characterized in that:
[0005] The wrap angle of the first cam lobe is 94°~124°, the wrap angle of the second cam lobe is 150°~175°, the valve opening angle of the intake cam is 331°~353° crankshaft angle, the valve closing angle is 527°~551° crankshaft angle, the valve opening angle of the exhaust cam is 118°~130° crankshaft angle, and the valve closing angle is 360°~375° crankshaft angle.
[0006] In some embodiments, the first cam includes an intake opening transition section, an intake lift section, an intake closing section and an intake closing transition section connected in sequence, the intake opening transition section has a wrap angle of 8° to 15°, the intake lift section has a wrap angle of 39° to 54°, the intake closing section has a wrap angle of 39° to 54°, and the intake closing transition section has a wrap angle of 8° to 15°.
[0007] In some embodiments, the wrap angle of the intake opening transition section is 10°, the wrap angle of the intake lift section is 50°, the wrap angle of the intake closing section is 50°, and the wrap angle of the intake closing transition section is 10°.
[0008] In some embodiments, the second cam includes an exhaust opening transition section, an exhaust lift section, an exhaust closing section and an exhaust closing transition section connected in sequence, the exhaust opening transition section has a wrap angle of 20° to 25°, the exhaust lift section has a wrap angle of 55° to 62.5°, the exhaust closing section has a wrap angle of 55° to 62.5°, and the exhaust closing transition section has a wrap angle of 20° to 25°.
[0009] In some embodiments, the wrap angle of the exhaust opening transition section is 22.5°, the wrap angle of the exhaust lift section is 60.5°, the wrap angle of the exhaust closing section is 60.5°, and the wrap angle of the exhaust closing transition section is 22.5°.
[0010] In some embodiments, the valve opening angle of the intake cam is 340° crankshaft angle, the valve closing angle is 540° crankshaft angle, and when the intake valve lift is maximum, the intake cam angle is 440° crankshaft angle.
[0011] In some embodiments, the valve opening angle of the exhaust cam is 126° crankshaft angle, the valve closing angle is 368° crankshaft angle, and when the exhaust valve lift is maximum, the exhaust cam angle is 247° crankshaft angle.
[0012] The utility model also proposes a premixed gas engine having a camshaft as described in any one of the above claims, wherein when the camshaft acts on an intake valve, the maximum lift of the intake valve is 7.1 mm to 7.8 mm, and when the camshaft acts on an exhaust valve, the maximum lift of the exhaust valve is 10.7 mm to 11.5 mm.
[0013] Compared with the prior art, the gas engine and camshaft provided by the utility model have the following beneficial effects:
[0014] By modifying the camshaft blank of the diesel engine, without adding new processes and technologies, the parameters such as the wrap angle, valve opening angle, and valve closing angle of the cam profile are reasonably designed to meet the intake and exhaust requirements of the gas engine camshaft. Since the camshaft is developed based on the camshaft blank of the same type of diesel engine, the commonality of gas engines and diesel engines is guaranteed, and the manufacturing cost is almost not increased, which has strong cost and process advantages for mass production.
[0015] By rationally designing the profiles of the intake cam and exhaust cam and optimizing the intake and exhaust valve lift curves, the motion acceleration is reduced, the motion loss is reduced, and the mechanical efficiency is improved compared to the prototype engine.
[0016] The gas engine adopting the camshaft proposed by the utility model retains the exhaust valve lift and timing value to the greatest extent, ensuring clean exhaust of exhaust gas, while reasonably reducing the intake lift and timing value, and having a smaller valve overlap angle. It is found in practice that the engine can still ensure a relatively stable speed under no-load and low-load conditions. After the exhaust emission test, there is no abnormal escape of the mixed gas, no exhaust gas reflux in the cylinder and no exhaust gas reflux in the exhaust duct, and the design is reasonable. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The preferred implementation modes will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present utility model.
[0018] Figure 1 It is a structural schematic diagram of the intake cam profile in the preferred embodiment of the utility model;
[0019] Figure 2 It is a structural schematic diagram of the exhaust cam profile in the preferred embodiment of the utility model;
[0020] Figure 3 It is a lift curve diagram of the intake valve and the exhaust valve in the preferred embodiment of the utility model;
[0021] Figure 4 It is a schematic diagram of the structure of the valve train assembly.
[0022] Description of Figure Numbers:
[0023] Camshaft 0; first base circle 1; first cam lobe 2; intake opening transition section 21; intake lift section 22; intake closing section 23; intake closing transition section 24; second base circle 3; second cam lobe 4; exhaust opening transition section 41; exhaust lift section 42; exhaust closing section 43; exhaust closing transition section 44; tappet 5; rocker arm 6; rocker arm shaft 7; push rod 8; valve 9; valve spring 91. DETAILED DESCRIPTION
[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.
[0025] The present application optimizes the shape and structure of a common diesel engine camshaft, and through calculations of thermodynamics and the kinematics and dynamics of the valve mechanism, the intake cam profile and the exhaust cam profile are machined within the wrap angle range of the intake cam profile and the exhaust cam profile of the prototype diesel engine, thereby obtaining an intake cam profile that can meet the intake requirements of a premixed gas engine, and an exhaust cam profile that meets the exhaust requirements, thereby laying a key foundation for improving the performance of the gas engine.
[0026] The engine camshaft provided in the embodiment of the utility model comprises an intake cam and an exhaust cam, wherein the intake cam has an intake cam profile, and the exhaust cam has an exhaust cam profile.
[0027] The intake cam profile and the exhaust cam profile both have parameters required by thermodynamics, including a wrap angle, a valve opening angle, and a valve closing angle. At the same time, they also have parameters that include the kinematic and dynamic requirements of the valve mechanism, including the maximum acceleration, maximum speed, and curvature radius of the intake cam lobe tip of the intake cam profile, the maximum acceleration, maximum speed, and curvature radius of the exhaust cam profile at the tip of the exhaust cam lobe, etc.
[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings.
[0029] Figure 1 Schematic diagram of the structure of the intake cam profile in the present invention. Figure 1 As shown, the intake cam profile includes a first base circle 1 and a first cam lobe 2. The center of the first base circle 1 coincides with the radial center of the first cam lobe 2. The diameter of the first base circle 1 is 37 mm to 39 mm, preferably 38 mm; the wrap angle of the first cam lobe 2 is 94° to 124°, preferably 120°.
[0030] The first cam 2 includes an intake opening transition section 21, an intake lift section 22, an intake closing section 23 and an intake closing transition section 24 in sequence; the wrap angle of the intake opening transition section 21 is 8° to 15°, preferably 10°; the wrap angle of the intake lift section 22 is 39° to 54°, preferably 50°; the wrap angle of the intake closing section 23 is 39° to 54°, preferably 50°; the wrap angle of the intake closing transition section 24 is 8° to 15°, preferably 10°. When the intake cam acts on the intake valve, the maximum lift of the intake valve is 7.1mm to 7.8mm, preferably 7.5mm.
[0031] Figure 2 Schematic diagram of the exhaust cam profile in the present invention. Figure 2As shown, the exhaust cam profile includes a second base circle 3 and a second cam lobe 4, the center of the second base circle 3 coincides with the radial center of the second cam lobe 4, the diameter of the second base circle 3 is 37mm to 39mm, preferably 38mm; the wrap angle of the second cam lobe 2 is 150 to 175°, preferably 166°.
[0032] The second cam 4 includes an exhaust opening transition section 41, an exhaust lift section 42, an exhaust closing section 43 and an exhaust closing transition section 44 connected in sequence; the exhaust opening transition section 41 has a wrap angle of 20° to 25°, preferably 22.5°; the exhaust lift section 42 has a wrap angle of 55° to 62.5°, preferably 60.5°; the exhaust closing section 43 has a wrap angle of 55° to 62.5°, preferably 60.5°; the exhaust closing transition section 44 has a wrap angle of 20° to 25°, preferably 22.5°. When the exhaust cam acts on the exhaust valve, the maximum lift of the exhaust valve is 10.7mm to 11.5mm, preferably 11mm.
[0033] It can be understood that the intake opening transition section 21, the intake closing transition section 24, the exhaust opening transition section 41 and the exhaust closing transition section 44 are transition curves between the base circle and the working profile, which are used to eliminate adverse effects in kinematics and dynamics, thereby improving the corresponding motion characteristics and processing technology characteristics of the cam.
[0034] In this embodiment, the valve opening angle of the intake cam is preferably 331° to 353° crankshaft angle, more preferably 340° crankshaft angle, and the valve closing angle of the intake cam is preferably 527° to 551° crankshaft angle, more preferably 540° crankshaft angle. The valve opening angle of the exhaust cam is preferably 118° to 130° crankshaft angle, more preferably 126° crankshaft angle; the valve closing angle of the exhaust cam is preferably 360° to 375° crankshaft angle, more preferably 368° crankshaft angle.
[0035] In order to better understand the working process of the camshaft in this embodiment, the gas engine camshaft proposed by the utility model is described below in conjunction with the valve transmission assembly.
[0036] like Figure 4 As shown, the valve transmission assembly includes a camshaft 0, a tappet 5, a push rod 8, a rocker arm 6 and a valve 9. The cam surface of the camshaft 0 abuts against the tappet 5. The two ends of the push rod 8 are respectively hinged to the tappet 5 and the rocker arm 6. The rocker arm 6 is rotatably connected to the rocker arm shaft 7 to drive the valve 9 to open. When the valve 9 is in a closed state, there is a valve clearance between the rocker arm 6 and the valve 9.
[0037] During operation, when the camshaft 0 rotates, the cam surface of the camshaft 0 acts on the tappet 5, causing the tappet to drive the rocker arm 6 to swing through the push rod 8. The rocker arm 6 can move closer to or away from the valve 9 during the swinging process to achieve the opening or automatic closing of the valve 9.
[0038] It is understandable that the valve 9 has a valve spring 91. When the rocker arm 6 applies pressure to the valve 9, the valve spring 91 is gradually compressed. When the force of the rocker arm 6 on the valve 9 is cancelled, the valve spring 91 drives the valve 9 to reset through elastic deformation, so that the valve 9 is automatically closed.
[0039] In a specific embodiment, the present invention provides a gas engine camshaft, comprising an intake cam and an exhaust cam.
[0040] The intake cam has an intake cam profile, which includes a first base circle 1 and a first cam lobe 2, and the center of the first base circle 1 coincides with the radial center of the first cam lobe 2.
[0041] The diameter of the first base circle 1 is 38 mm, and the wrap angle 11 of the first cam lobe 2 is 120°.
[0042] The profile of the first cam lobe 2 includes an intake opening transition section 21, an intake lift section 22, an intake closing section 23 and an intake closing transition section 24 in sequence. The wrap angle of the intake opening transition section 21 is 10°, and the wrap angle of the intake lift section 22 is 50°; the wrap angle of the intake closing section 23 is 50°, and the wrap angle of the intake closing transition section 24 is 10°. When the intake cam acts on the intake valve, the maximum lift of the intake valve is 7.50 mm.
[0043] The exhaust cam has an exhaust cam profile, which includes a second base circle 3 and a second cam lobe 4. The center of the second base circle 3 coincides with the radial center of the second cam lobe 4.
[0044] The diameter 2 of the second base circle 3 is 38 mm, and the wrap angle 11 of the cam peach is 166°.
[0045] The second cam 4 includes an exhaust opening transition section 41, an exhaust lift section 42, an exhaust closing section 43 and an exhaust closing transition section 44 in sequence. The exhaust lift section 42 has a wrap angle of 60.5°, the exhaust closing section 43 has a wrap angle of 60.5°, and the exhaust closing transition section 44 has a wrap angle of 22.5°.
[0046] According to the gas engine camshaft proposed in this embodiment, its intake and exhaust process is as follows:
[0047] Before the rocker arm 6 contacts the intake valve, the valve clearance of the intake valve must be offset. In the initial state, the clearance between the rocker arm 6 and the intake valve is 0.3 mm, and the maximum lift of the intake opening transition section 21 and the intake closing transition section 24 is 0.1 mm. When the intake cam rotates 320° to 340° crankshaft angle, the intake opening transition section 21 and the intake lift section 22 contact the tappet 8 in turn, so that the rocker arm 6 gradually approaches the intake valve until the valve clearance is offset. When the intake cam rotates by 340° to 440° of crankshaft angle, the intake lift section 22 maintains contact with the tappet 8, so that the rocker arm 6 drives the intake valve to move, thereby opening the intake valve, the valve spring is gradually compressed, and the intake valve lift gradually increases to 7.5mm; when the intake cam rotates by 440° to 540° of crankshaft angle, the intake closing section 23 maintains contact with the tappet 5, the tappet 5 drives the rocker arm 6 to move in the opposite direction, the valve spring drives the intake valve to gradually reset, and the intake valve lift gradually decreases until the intake valve is completely closed; when the intake cam rotates by 540° to 560° of crankshaft angle, the intake closing section 23 and the intake closing buffer section 24 contact with the tappet 8 in turn, so that the rocker arm 6 gradually moves away from the intake valve, and the valve clearance of the intake valve gradually increases to 0.3mm.
[0048] Before the rocker arm 6 contacts the exhaust valve, the valve clearance of the exhaust valve needs to be offset. In the initial state, the clearance between the rocker arm 6 and the exhaust valve is 0.5 mm, and the maximum lift of the exhaust opening transition section 41 and the exhaust closing transition section 24 is 0.15 mm. When the exhaust cam rotates 81° to 126° crankshaft angle, the exhaust opening transition section 41 and the exhaust lift section successively keep in contact with the tappet 8, so that the rocker arm 6 gradually approaches the exhaust valve until the valve clearance is offset. When the exhaust cam rotates 126° to 247° crankshaft angle, the exhaust lift section 42 keeps in contact with the tappet 8, so that the rocker arm 6 drives the exhaust valve to move, thereby opening the exhaust valve, the valve spring is gradually compressed, and the exhaust valve lift gradually increases to 11 mm. When the exhaust cam rotates by 247° to 368° of crankshaft angle, the exhaust closing section 43 keeps in contact with the tappet 8, and the tappet 8 drives the rocker arm 6 to drive the exhaust valve to move in the opposite direction. The valve spring drives the exhaust valve to gradually reset, and the exhaust valve lift gradually decreases until the exhaust valve is completely closed. When the exhaust cam rotates by 368° to 413° of crankshaft angle, the exhaust closing section 43 and the exhaust closing transition section 44 contact the tappet in turn, so that the rocker arm 6 gradually moves away from the exhaust valve, and the valve clearance of the exhaust valve gradually increases to 0.5mm.
[0049] The difference between the exhaust valve closing angle and the intake valve opening angle is the valve overlap angle. The valve overlap angle in this embodiment is smaller, which means that the exhaust valve and the intake valve are open at the same time for a short time, and the amount of exhaust gas flowing back into the cylinder under low-speed conditions is small.
[0050] In summary, the gas engine with the camshaft proposed by the utility model does not add new processes or technologies. By modifying the camshaft of the diesel engine, the parameters such as the wrap angle of the cam profile, the valve opening angle, the valve closing angle, and the valve lift are optimized and designed. While meeting the intake and exhaust requirements of the gas engine camshaft, the commonality with the original machine parts is guaranteed, and the manufacturing cost is almost not increased, which has strong cost and process advantages for mass production. In addition, the engine can still maintain a stable speed under no-load and low-load conditions. After the exhaust emission test, there is almost no abnormal escape of the mixed gas, and the design is reasonable.
[0051] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the utility model, and these improvements and modifications should also be regarded as the protection scope of the utility model.
Claims
1. A gas engine camshaft, comprising an intake cam and an exhaust cam, wherein the profile of the intake cam comprises a first base circle and a first cam lobe, and the profile of the exhaust cam comprises a second base circle and a second cam lobe, wherein: The wrap angle of the first cam lobe is 94°~124°, the wrap angle of the second cam lobe is 150°~175°, the valve opening angle of the intake cam is 331°~353° crankshaft angle, the valve closing angle is 527°~551° crankshaft angle, the valve opening angle of the exhaust cam is 118°~130° crankshaft angle, and the valve closing angle is 360°~375° crankshaft angle.
2. The gas engine camshaft according to claim 1, characterized in that: The first cam includes an intake opening transition section, an intake lift section, an intake closing section and an intake closing transition section connected in sequence. The wrap angle of the intake opening transition section is 8° to 15°, the wrap angle of the intake lift section is 39° to 54°, the wrap angle of the intake closing section is 39° to 54°, and the wrap angle of the intake closing transition section is 8° to 15°.
3. The gas engine camshaft according to claim 2, characterized in that: The wrap angle of the intake opening transition section is 10°, the wrap angle of the intake lift section is 50°, the wrap angle of the intake closing section is 50°, and the wrap angle of the intake closing transition section is 10°.
4. The gas engine camshaft according to claim 1, characterized in that: The second cam includes an exhaust opening transition section, an exhaust lift section, an exhaust closing section and an exhaust closing transition section connected in sequence, the exhaust opening transition section has a wrap angle of 20° to 25°, the exhaust lift section has a wrap angle of 55° to 62.5°, the exhaust closing section has a wrap angle of 55° to 62.5°, and the exhaust closing transition section has a wrap angle of 20° to 25°.
5. The gas engine camshaft according to claim 4, characterized in that: The wrap angle of the exhaust opening transition section is 22.5°, the wrap angle of the exhaust lift section is 60.5°, the wrap angle of the exhaust closing section is 60.5°, and the wrap angle of the exhaust closing transition section is 22.5°.
6. The gas engine camshaft according to claim 1, characterized in that: The valve opening angle of the intake cam is 340° crankshaft angle, the valve closing angle is 540° crankshaft angle, and when the intake valve lift is maximum, the intake cam angle is 440° crankshaft angle.
7. The gas engine camshaft according to claim 1, characterized in that: The valve opening angle of the exhaust cam is 126° crankshaft angle, the valve closing angle is 368° crankshaft angle, and when the exhaust valve lift is maximum, the exhaust cam angle is 247° crankshaft angle.
8. A gas engine, using the camshaft according to any one of claims 1 to 7, characterized in that: When the camshaft acts on the intake valve, the maximum lift of the intake valve is 7.1 mm to 7.8 mm, and when the camshaft acts on the exhaust valve, the maximum lift of the exhaust valve is 10.7 mm to 11.5 mm.