Internal combustion engine

Abstract

The invention discloses a valve mechanism of an internal combustion engine, which comprises a timing gear, a valve, a valve guide pipe, a valve seat, a transmission shaft, a bracket, a locking device and a connecting part, wherein the transmission shaft is distributed on a shaft body and is provided with a disc-shaped object and a shifting fork which have specific phases and correspond to a cylinder; the locking device is arranged on the bracket; and the connecting part is used for connecting the bracket and the valve. Opening and closing of an air valve are achieved through relative movement between an axial protrusion on a shifting fork on a transmission shaft and a groove in a connecting part, and sealing after the air valve is closed is achieved through cooperation and interaction of a fan-shaped arc end face of a disc-shaped object on the transmission shaft and a locking device on a support. The phenomenon that the valve is not closed and is opened by the cam rotating at a high speed when the valve mechanism of the internal combustion engine operates at a high speed is avoided, and the resonance phenomenon generated by the valve spring and the energy loss caused by the valve spring are avoided.

Description

2. Technical field:

[0001] The present invention relates to an internal combustion engine, and in particular to a valve train of the internal combustion engine. 3. Background technology:

[0002] At present, the valve train of a four-stroke internal combustion engine is composed of a valve train group and a valve group. The valve train group is all the parts from the timing gear to the valve action. Its composition varies depending on the form of the valve train. Its function is to drive the valve to open and close at a fixed time. The composition of the valve group has basically nothing to do with the form of the valve train. When this valve train is working, the valve exists in three states: valve opening process, valve closing process, and valve keeping closed process; the valve opening process is to drive the valve to open directly or indirectly through the rotation of the cam on the camshaft, and compress the valve spring at the same time; the valve closing process is that the valve is driven to close under the tension of the valve spring; the valve keeping closed process is that the valve is kept closed under the pre-tension of the valve spring. Since the forces for opening and closing the valve come from the cam and the valve spring respectively, and the directions of the forces acting on the valve are opposite, it is difficult to achieve perfect coordination when the forces are switched. Usually, when the speed of the internal combustion engine reaches a certain high, the valve is opened by the high-speed rotating cam before it is completely closed, causing the valve to separate from the cam; in addition, when the operating frequency of the valve spring is equal to or an integer multiple of the natural vibration frequency, the valve spring will resonate, and the valve timing will be destroyed during resonance, and the valve will rebound and impact; in addition, since the tension of the valve spring needs to be overcome to open the valve, the valve spring will produce a certain amount of energy loss.

[0003] IV. Purpose of the invention:

[0004] The purpose of the present invention is to overcome the defects of the existing internal combustion engine valve mechanism. By improving the valve transmission method of the internal combustion engine valve mechanism, the two processes of valve opening and valve closing are combined into one process of valve opening and closing, so as to achieve smooth conversion of the direction of the force acting on the valve, eliminate the phenomenon of separation of the mechanism contact parts, eliminate the resonance of the valve spring, and eliminate the energy loss caused by the valve spring.

[0005] V. Technical solution:

[0006] The valve train of an internal combustion engine of the present invention comprises a timing gear, a valve, a valve guide, and a valve seat, and is characterized in that: it also comprises a transmission shaft, a bracket, a locking device installed on the bracket, and a connecting portion connecting the bracket and the valve, with a disc-shaped object and a shift fork having a specific phase corresponding to the valve distributed on the shaft body; the shift fork is a support arm extending from the inside to the outside of the transmission shaft, and the end of the support arm has an axial protrusion, the axial projection of the disc-shaped object is a sector, and its central angle is β, and the axial projection of the protrusion intersects with the axial projection of the angular bisector of β; one end of the connecting portion is connected to the bracket, The other end is connected to at least one of the valves, and the axial projection of the middle part of the connecting part is an irregular sector shape, and its central angle is η, 115°≤η≤145°, and the η opens toward the valve, and a groove is provided on the disk surface, and the sum of η and β is equal to 360 degrees; the radial projection of the axis of the transmission shaft intersects perpendicularly with the radial projection of the center line of the bracket, the connecting part, and the valve; when the transmission shaft rotates, the protrusion moves relative to each other in the groove in some phases, and the fit is a clearance fit, and in other phases, the sector-shaped arc end face of the disk cooperates and interacts with the locking device.

[0007] 6. Beneficial effects:

[0008] The structural feature of the present invention is that the relative movement between the axial protrusion on the shift fork on the transmission shaft and the groove on the connecting part is used to drive the driven part composed of the bracket, the connecting part and the valve to move up and down, so as to realize the process from opening to closing of the valve, and the arc end face of the disk-shaped object on the transmission shaft cooperates and interacts with the locking device to realize the sealing after the valve is closed; the two are combined to simplify the valve opening process, closing process and valve keeping closed state process of the existing internal combustion engine valve mechanism into two parts: valve "opening and closing" process and valve "keeping closed state" process. In particular, the present invention realizes the smooth conversion of the direction of the force in the valve opening and closing process, so that the entire device removes the valve spring directly acting on the valve, so that the valve is effectively controlled during the working process, solves the problem of contact parts detaching when the existing internal combustion engine valve mechanism works at high speed, eliminates the valve spring resonance phenomenon and the energy loss caused by the valve spring.

[0009] 1: Energy consumption of valve spring:

[0010] Known conditions: Complete combustion of 1kg of gasoline can release 46000kj of heat.

[0011] Assumptions: A conventional four-cylinder gasoline engine with four valves in each cylinder runs at 2,000 rpm, with a force of 600N for each valve to open and a valve stroke of 10mm for one hour.

[0012] Valve spring energy consumption: = 1 hour * valve working times per minute * number of valves * valve opening force * stroke

[0013] Q (actual valve spring energy consumption) = 60*2000 / 2*16*600*0.01 = 5760 (kj);

[0014] 1L (93# gasoline) = 0.737kg;

[0015] Q(1L-93# gasoline)=46000*0.737=33902(kj);

[0016] Q(actual valve spring fuel consumption) = Q(actual valve energy consumption) / Q(1L-93# gasoline)

[0017] =5760 / 33902=0.170(L)=170(ml);

[0018] 2: The influence of resonance on the valve mechanism:

[0019] Due to the existence of valve springs in the existing internal combustion engine valve train, the entire valve train constitutes an elastic system. The operating frequency of the valve spring overlaps with its natural frequency to produce resonance, causing valve rebound impact and affecting the normal operation of the internal combustion engine.

[0020] 3: The impact of high speed on the valve mechanism:

[0021] a: Assume that the speed of an internal combustion engine is 8000 rpm;

[0022] b: Assume that the time it takes for the valve spring to close the valve is 0.02 seconds;

[0023] Because the camshaft speed is half of the crankshaft speed, 8000 / 2 / 60=200 / 3 (rev / second), the time for the camshaft to rotate one circle is 3 / 200 seconds. If the time required for the valve to close under the action of the valve spring tension is greater than 15 thousandths of a second, the valve will not close tightly, and the intake and exhaust valves may even be open, disrupting the normal working cycle of the internal combustion engine.

[0024] VII. Illustrations:

[0025] Figure 1 Schematic diagram of the principle of the present invention;

[0026] Figure 2 Parts diagram of the present invention;

[0027] Figure 3 Assembly diagram of an embodiment of the present invention;

[0028] Figure 4 An exploded view of an embodiment of the present invention;

[0029] Figure 5 Other forms of the present invention 1 assembly diagram;

[0030] Figure 6 Other forms of the present invention 1 Exploded view;

[0031] Figure 7 Other forms of the present invention 2 assembly diagram;

[0032] Figure 8 Other forms of the present invention 2 Exploded view;

[0033] Fig. 9 Other forms of the present invention 3 assembly diagram;

[0034] Fig.10 Other forms of the present invention 3 explosion view;

[0035] Fig.11 A schematic diagram of the thrust profile of the valve train of the present invention;

[0036] Fig.12 Schematic diagram of the pressure angle of the valve train of the present invention.

[0037] In the figure, 1 is the timing gear, 2 is the transmission shaft, 2-1 is the arc end face of the disc-shaped sector disk, 2-2 is the axial cylindrical protrusion (roller) on the shift fork, 3 is the connecting part, 3-1 is the lifting ear on the connecting part, 3-2 is the groove on the lower half of the connecting part, 4 is the bracket, 5 is the valve, 6 is the key, 7 is the shaft head lock nut, 8 is the pin, 9 is the small pin, 10 is the valve guide, 11 is the valve seat, 12 is the locking device = positioning bead, η is the center angle corresponding to the theoretical outline of the groove, η = ∠COD, β is the center angle of the sector disk, β = ∠EOF, A is the shift fork, B is the disc-shaped object, and CD is the theoretical outline of the groove.

[0038] 8. Best Practice:

[0039] In order to simplify the structure of the present invention, the disc-shaped object (fan-shaped disc) and the shift fork on the transmission shaft are overlapped as one in this embodiment. After the combination, fan-shaped discs with specific phases are distributed on the transmission shaft, and an axial protrusion is provided on the bisector of the central angle of the fan-shaped disc. This embodiment realizes the present invention by utilizing the protrusion on the fan-shaped disc to drive the driven part.

[0040] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown: the active part of the valve train of the internal combustion engine includes a timing gear 1 and a transmission shaft 2, and the driven part includes a connecting part 3, a bracket 4 and a valve 5; the valve guide 10 and the valve seat 11 are installed on the cylinder head in a static fit manner.

[0041] Timing gear: In this embodiment, the timing gear 1 is no different from the timing gear used in existing internal combustion engines.

[0042] Transmission shaft: After the sector disk and the shift fork on the transmission shaft 2 are combined, there is an axial cylindrical protrusion 2-2 on the angular bisector of the sector disk. The diameter of the protrusion 2-2 is equal to the width of the groove 3-2 on the connecting part 3. The central angle of the sector disk is β, β=∠EOF.

[0043] Connection: Figure 2 , Figure 4 As shown: the upper half of the connecting portion 3 is a long strip, and the lower half is a crescent shape. A "cross" shaped opening groove is opened in the upper half of the connecting portion 3. The radial width of the groove is equal to the diameter of the corresponding transmission shaft journal, and the axial width of the groove is equal to the thickness of the fan-shaped disk on the transmission shaft 2. The top end of the "cross" shaped opening groove is provided with a lifting ear 3-1. The hole of the lifting ear 3-1 is axial, and the diameter of the hole is equal to the diameter of the hole matched with it on the bracket 4. A groove 3-2 is radially opened in the lower half of the connecting portion 3. The theoretical contour line CD of the groove is a smooth curve. The central angle corresponding to the theoretical contour line CD of the groove is η, η= / COD, and the η angle opens downward. The grooves 3-2 are opposite and mirror images of each other, and are located inside the connecting portion 3, η+β=360°, 115°≤η≤145°. There is a vertical hole at the bottom of the connecting portion 3, and the diameter of the hole is equal to the diameter of the valve stem.

[0044] Bracket: As Figure 2 , Figure 4 As shown: In this embodiment, the bracket 4 is in a "cross" shape when viewed from above, and the two "vertical" ends of the "cross"-shaped bracket 4 are axially opened with holes, the diameter of the holes is equal to the hole diameter of the connecting part ear 3-1, and there is a preset vertical hole in the middle of the "cross" for installing the locking device 12.

[0045] Locking device: The locking device adopts a positioning bead 12.

[0046] This embodiment is connected in the following manner: Figure 3 As shown: the timing gear 1 is connected to the transmission shaft 2 through a key 6, a keyway and a shaft head lock nut 7; Figure 4 As shown: the "X"-shaped opening groove of the connecting part 3 is passed through the corresponding transmission shaft journal, and the fan-shaped disk on the transmission shaft 2 is placed in the "X"-shaped opening groove, and the cooperation between the transmission shaft journal and the opening groove, and between the fan-shaped disk and the opening groove is a clearance fit; the ear 3-1 at the top of the opening groove cooperates with the hole on the bracket 4, and is fixedly connected by a pin 8 in a static fit manner; the hole at the bottom of the connecting part 3 cooperates with the valve stem, and is fixedly connected by a pin 9; the positioning bead 12 is installed in the mounting hole reserved on the bracket 4 in a static fit manner.

[0047] When the timing gear 1 drives the transmission shaft 2 to rotate, the arc end face 2-1 of the sector disk cooperates and interacts with the positioning bead 12 installed on the bracket 4, and the valve 5 is in a closed state. Since the distance between the lowest point of the positioning bead 12 and the axis of the transmission shaft is less than the radius of the sector disk, the positioning bead 12 is squeezed by the arc end face 2-1 of the sector disk, so that it generates a force opposite to the opening direction of the valve 5. The opposite force causes the bracket 4, the connecting part 3, and the valve 5 to generate a movement trend opposite to the opening direction of the valve 5, so that the valve 5 and the valve seat 11 fit tightly, and the valve 5 is sealed after closing. The rotation angle of the transmission shaft 2 during this period is β, and the valve 5 is in a closed state within this rotation angle; when the arc end face 2-1 of the sector disk cooperates with the positioning bead 12 installed on the bracket 4, the valve 5 is in a closed state within this rotation angle. 2 is separated, the axial protrusion 2-2 on the sector disk enters the groove 3-2 in the lower half of the connection part 3, and the protrusion 2-2 moves in the groove 3-2. The two are matched with a clearance fit. Since the valve 5 is constrained by the valve guide 10, the valve 5, the connection part 3 and the bracket 4 can only move along the center line of the valve guide 10. Since the difference between the distance from the point on the theoretical groove contour CD to the axis of the transmission shaft and the radius of gyration OC is from small to large and then from large to small, when the transmission shaft 2 rotates, the valve 5 gradually opens from the closed state to the maximum lift, and then from the maximum lift to the closed state, completing the opening and closing process of the valve 5. The rotation angle of the transmission shaft 2 during this period is η. Since η+β=360°, as the transmission shaft 2 rotates, it enters the next cycle and repeats. [Note: Ф (推程运动角) =η / 2Ф (回程运动角) =η / 2Ф S(近休止角) =βη+β=360°]

[0048] In the above-mentioned embodiment, the connecting portion is connected to one valve, but it can also be connected to two or more valves of the same type in the same cylinder through some connection methods.

[0049] In the above-mentioned embodiment, the locking device of the valve mechanism of the internal combustion engine adopts a positioning bead. When the positioning bead is squeezed by the arc end face of the fan-shaped disk, the spring inside the positioning bead is compressed, so that the spring tension generated by it causes the valve to remain in a closed state; the locking device can also install a steel leaf spring or other elastic material on the bracket, as long as it is squeezed by the arc end face of the fan-shaped disk, the bracket, connecting part, and valve will produce a movement trend opposite to the valve opening direction, and the valve and the valve seat can fit tightly.

[0050] The valve mechanism of the internal combustion engine of the present invention realizes light load operation during operation, so the material can be 40Cr, surface quenched to 56-60HRC, or 38CrMoA1, nitrided to 60-67HRC. In this embodiment, materials such as 20Cr, 20CrMn, etc., which are surface quenched to a hardness of 55-60HRC, should also be suitable.

[0051] The above embodiment is characterized in that the shift fork on the transmission shaft rotates, and the relative movement between the shift fork and the groove on the connection part drives the connection part to move up and down to drive the valve to open and close. Its structural feature is that the shift fork and the fan-shaped disk are combined into one, so that the structure of the transmission shaft is relatively simple and easy to process and manufacture, and the entire valve mechanism is compact. The disadvantage is that the mass of the connection part is slightly large and the motion inertia is relatively large. Of course, the implementation method can also adopt other layout arrangements, such as Figure 5 , Figure 6 As shown: the connection part is located between two sector disks, and grooves are provided on both sides of the lower part of the connection part to match the axial cylindrical protrusions on the sector disks. This layout is conducive to reducing the mass of the connection part and can reduce the motion inertia; Figure 7 , Figure 8 The fan-shaped disc and the fork on the transmission shaft are independent and have the same layout. Figure 5 , Figure 6 similar; Fig. 9 , Fig.10 The fan-shaped disc and the fork on the transmission shaft are also independent, and the layout is the same as Figure 7 , Figure 8 Similar, except that the fork on the transmission shaft is inside the connection; there is also a Fig. 9 , Fig.10 The structure is opposite, with shift forks arranged on both sides of the connecting part and a sector-shaped disc inside the connecting part.

[0052] The above embodiment and the internal combustion engine valve mechanism described later all use a double fork structure for each unit, in order to make the entire mechanism run more stably. In fact, each unit can also use a single fork structure, which is simpler! But the stability is not as good as the double fork structure.

[0053] The internal combustion engine valve mechanism of the present invention belongs to the category of cam mechanism and is a variant of cam mechanism. In addition, the method of maintaining high-pair contact in the existing internal combustion engine valve mechanism (valve opening and closing) is achieved by force locking, and the force for opening and closing the valve comes from the cam and the valve spring. The method of maintaining high-pair contact in the internal combustion engine valve mechanism of the present invention (valve opening and closing) is achieved by form locking, and the force on the valve comes from the shift fork; when the valve of the existing internal combustion engine valve mechanism is in a closed state, the sealing of the valve is affected by the pre-tensioning force of the valve spring, while the present invention is achieved by the cooperation and interaction between the arc end face of the fan-shaped disk and the locking device, which is similar to the force-locking type disc cam mechanism.

[0054] Regarding the selection of the motion law of the follower in the valve mechanism of an internal combustion engine, the motion law of the valve in the existing valve mechanism of an internal combustion engine generally adopts the fifth-order polynomial motion law (the profile of the cam determines the valve motion law), and the characteristic of the fifth-order polynomial motion law is that it is "suitable for high speed and medium load". The valve mechanism of the internal combustion engine of the present invention does not have a valve spring directly acting on the valve, thereby realizing light load operation. The valve motion law can select the "sinusoidal acceleration motion law", and the characteristic of the sinusoidal acceleration motion law is that it is "suitable for high speed and light load". By changing the valve motion law, the cam profile is improved, thereby improving the ventilation efficiency of the internal combustion engine.

[0055] The extrapolated profile equation is:

[0056] Use the inversion method to establish a coordinate system and find the coordinates of the high-pair contact point; as shown in Figure 11:

[0057] Base circle radius r b ; offset distance e; B0 is the starting point of the push stroke; B is the arbitrary contact point of the high pair (roller center); O is the rotation center; S is the displacement of the follower; the roller radius is r r ; tanθ is the slope of the normal line at point B; h is the stroke.

[0058] BB'=S A'B'=S0A'B=S0-S

[0059]

[0060]

[0061] The coordinates of point B are the coordinates of the roller center:

[0062] The actual profile equation of the groove wall is:

[0063]

[0064]

[0065] Pressure angle: As shown in Figure 12:

[0066] lop=V / ω(point p is the relative instantaneous center) tanα=(e+lop) / (S0-S)

[0067] Because: S0 2 +e 2 =r b 2 So: tanα=(e+lop) / [(r b 2 -e 2 ) 1 / 2 -S]

[0068] Base circle radius;

[0069]

[0070] α<[α](allowable pressure angle)pressure angle range(25°-35°)

[0071]

[0072] S needs to satisfy the law of sinusoidal acceleration motion;

[0073] Right now:

[0074]

[0075]

[0076] Or S satisfies the law of motion of a quintic polynomial;

[0077] Right now:

[0078]

[0079]

[0080] A buffer section needs to be set at the connection between the near rest and the push stroke, and the connection between the return stroke and the near rest. A smooth transition needs to be ensured at the connection between the push stroke and the return stroke. The Camtra plug-in in the SolidWorks software is used to generate the cam.

Claims

1. A valve train for an internal combustion engine comprising a timing gear, a valve, a valve guide, and a valve seat, characterized in that: It also includes a transmission shaft, a bracket, a locking device installed on the bracket, and a connecting part connecting the bracket and the valve, with a disc and a fork distributed on the shaft body with a specific phase corresponding to the valve; the fork is a support arm extending from the inside to the outside of the transmission shaft, and the end of the support arm has an axial protrusion, the axial projection of the disc is a sector, and its center angle is β, and the axial projection of the protrusion intersects with the axial projection of the angular bisector of β; one end of the connecting part is connected to the bracket, and the other end is connected to at least one of the valves, the middle axial projection of the connecting part is an irregular sector, and its center angle is η, and the η opens toward the valve, and a groove is opened on the disc surface, and the sum of η and β is equal to 360 degrees; the radial projection of the transmission shaft axis intersects perpendicularly with the radial projection of the center line of the bracket, the connecting part, and the valve; when the transmission shaft rotates, the protrusion moves relatively in the groove in some phases, and its cooperation is a clearance cooperation, and in other phases, the sector arc end face of the disc cooperates and interacts with the locking device.

2. The valve train of an internal combustion engine according to claim 1, characterized in that: 115°≤η≤145°.

3. The valve train of an internal combustion engine according to claim 1, characterized in that: The theoretical profile of the groove is a smooth curve.

4. The valve train of an internal combustion engine according to claim 1, characterized in that: The contact point between the locking device and the arc end surface of the sector disk of the disk-shaped object B is a pointed bottom, a flat bottom, a curved bottom or a roller.

Images