A diesel engine timing automatic tensioning sprocket

Abstract

This invention discloses an automatic timing tensioning sprocket for a diesel engine, comprising a bolt with holes; an upper plate and a lower plate, each with a large circular hole in the center for the bolt to pass through, a small circular hole at the upper end of the large circular hole for a clamping bolt to pass through, and a threaded hole at the lower end of the large circular hole in the upper plate for a threaded plug or locking bolt to pass through; spring grooves on the inner surfaces of the upper and lower plates, and limiting grooves on the outer sides of the spring grooves; a sprocket spring disposed in the spring groove, with a pin hole and a spring hole on the lower side of the sprocket spring, the spring hole being connected to the bolt shaft at the end of the locking bolt; and a movable chain link clamped in the limiting grooves of the upper and lower plates, which can freely extend and retract radially within the limiting grooves. This application reduces the number of parts, increases the parts standardization rate, and reduces costs; reduces the swing amplitude of the tight-side chain, extending the service life of the chain system; reduces the dynamic tension of the timing system, reducing NVH levels; and reduces timing errors caused by chain elongation.

Description

Technical Field

[0001] This invention relates to the field of timing chain technology, and in particular to an automatic timing tension sprocket for a diesel engine. Background Technology

[0002] The timing chain system is the mechanism by which the engine transmits power from the crankshaft to the camshaft via a chain, enabling the valves to open and close at the correct times, thus allowing the engine to operate continuously. The timing system directly affects the valve timing; if a problem occurs in the timing chain system, the valves and pistons will collide, preventing the engine from operating.

[0003] During the rotation of the engine crankshaft, the speed of the crankshaft sprocket and the torque of the camshaft sprocket will fluctuate significantly under different crankshaft angles. Therefore, when the chain system is subjected to complex external forces, the chain will have a large swing amplitude. During the movement, the chain system will experience more severe friction and collision, which will affect the life of the chain system and make the system noisier.

[0004] The existing diesel engine timing chain system has the following main disadvantages: (1) The entire timing system has many parts, including crankshaft sprocket, camshaft sprocket, tensioner, fixed rail, moving rail, bolts and other parts. Moreover, the commonality rate of parts of different timing systems is very low, resulting in higher costs and larger required layout space. (2) The timing chain system has no tensioner on the tight side. During operation, the chain on the tight side fixed rail will produce a small swing due to the change in torque and speed of the camshaft sprocket. This will aggravate the wear of the system and greatly reduce the service life of the chain system. (3) Since the timing system has a large number of chain links on the loose side, in order to prevent tooth skipping, a tensioner is needed to press down the moving rail. This will increase the dynamic tension of the system, increase the NVH level, and reduce the service life of the chain system. (4) Because the chain is under tension for a long time, it will cause the chain to elongate. This will cause a certain error in timing, affect the combustion efficiency of the engine, and in severe cases, the valve may hit the piston, leading to engine failure. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an automatic timing tension sprocket for diesel engines, which reduces the number of parts, increases the commonality rate of parts, reduces costs, and is easy to arrange; reduces the swing amplitude of the tight side chain, and increases the service life of the chain system; reduces the dynamic tension of the timing system, and reduces NVH level; and reduces timing error caused by chain elongation.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0007] An automatic timing tensioner sprocket for a diesel engine, comprising:

[0008] Hollow bolts with holes are used to secure the automatic tensioning sprocket to the camshaft.

[0009] Both the upper plate and the lower plate have a large circular hole in the center for the bolt with holes to pass through. The upper end of the large circular hole is provided with a small circular hole for the clamping bolt to pass through. The lower end of the large circular hole in the upper plate is provided with a pair of threaded holes for the thread plug or locking bolt to pass through. The inner surfaces of the upper plate and the lower plate are provided with spring grooves. The outer side of the spring groove is provided with limit grooves at equal intervals along the circumferential direction.

[0010] A sprocket spring is detachably mounted in a spring groove in the upper plate. A pin hole for accommodating a movable pin is provided on the lower side of the sprocket spring. Spring holes are symmetrically arranged on both sides of the pin hole. The spring holes are connected to the bolt shaft at the end of the locking bolt.

[0011] The movable link is clamped in the limiting groove of the upper plate and the lower plate, and the movable link can freely extend and retract in the radial direction within the limiting groove.

[0012] Preferably, the perforated bolt is an M14 hollow bolt with a length of 52mm and an oil passage with a diameter of 6mm; the perforated bolt is used to fix the automatic tensioning sprocket to the camshaft and can introduce the oil in the camshaft into the automatic tensioning sprocket to provide tension for the automatic tensioning sprocket.

[0013] Preferably, the clamping bolt is an M6 ordinary bolt with a length of 15mm; the clamping bolt can pass through the small round holes of the upper plate and the lower plate and fix them together to prevent the movable chain link from falling out of the upper plate and the lower plate when the bolt with the hole is not installed.

[0014] Preferably, the threaded plug is an M4 ordinary threaded plug with a length of 5mm; the threaded plug is used to block the two threaded holes at the lower end of the large round hole on the upper plate to prevent oil from leaking out from the automatic tensioning sprocket.

[0015] Preferably, the locking bolt is an M4 ordinary bolt with a thread length of 4.5mm; the two bolt shafts at the end of the locking bolt respectively cooperate with the two spring holes to lock the sprocket spring to the ultimate compression state, so that the movable chain links form the minimum pitch circle diameter, which facilitates the assembly of the automatic tensioning sprocket onto the camshaft.

[0016] Preferably, the upper plate is provided with 26 limiting grooves, which are used to assemble movable chain links, and the movable chain links can slide freely in the radial direction within the limiting grooves; the upper plate is also provided with spring grooves, which are used to assemble the sprocket springs, and the sprocket springs can deform within the spring grooves.

[0017] Preferably, the pin hole consists of two semi-circular holes with a break in the middle. When the sprocket spring is compressed to its limit, the cross-sections are flush, forming a circular pin hole. When the spring is not subjected to external force and is freely extended, there is a certain gap between the two semi-circular holes.

[0018] Preferably, the movable pin is a common cylindrical pin with a diameter of 5mm and a height of 9mm; the movable pin is used to block the gap caused by the relaxation of the sprocket spring, preventing oil from leaking out of the automatic tensioning sprocket.

[0019] Preferably, the thickness of the movable link is less than the gap between the upper plate and the lower plate to ensure that the movable link can extend and retract radially within the limiting groove.

[0020] Preferably, the lower plate is used to lock part of the degrees of freedom of the movable link and the sprocket spring.

[0021] The above-described technical solution of the present invention has the following beneficial effects:

[0022] (1) The timing system with automatic tensioning camshaft sprocket assembly can eliminate the need for three components: tensioner, fixed rail, and moving rail. The system can consist of only three components: automatic tensioning camshaft sprocket assembly, crankshaft sprocket, and chain, which greatly reduces the cost and layout difficulty.

[0023] (2) Since each link in the automatic tensioning camshaft sprocket assembly can move radially, the drastically changing load force can be transmitted to the spring and internal oil pressure for buffering. At the same time, it has a variable center distance function, which greatly reduces the tight side swing caused by speed and load, and increases the system life.

[0024] (3) Because the timing system with automatic tensioning camshaft sprocket assembly has a strong buffering and adjustment effect, its initial spring force and dynamic oil pressure are lower than those of ordinary timing system. Therefore, the dynamic tension during the entire movement process is also much lower than that of ordinary timing system, which can greatly improve NVH effect.

[0025] (4) Since each link can extend and retract, it can compensate for the wear and elongation of the chain and keep the timing state basically consistent with the initial state. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0027] Figure 1 This is a schematic diagram of the automatic timing tensioner sprocket for the diesel engine in this application.

[0028] Figure 2 This is a cross-sectional view of the automatic timing tensioner sprocket for the diesel engine of this application.

[0029] Figure 3 This is an exploded view of the automatic timing tensioner sprocket of the diesel engine according to this application.

[0030] Figure 4A This is a schematic diagram showing the connection between the upper plate, sprocket spring, and movable chain link (the sprocket spring is in its ultimate compression state, and the movable chain link is in its minimum pitch circle state).

[0031] Figure 4B This is a schematic diagram showing the connection between the upper plate, sprocket spring, and movable chain link (the sprocket spring is in a slightly compressed state, and the movable chain link is in its maximum pitch circle state).

[0032] Figure 5A This is a diagram showing the ultimate compression state of the sprocket spring.

[0033] Figure 5B This is a diagram showing the sprocket spring in a small compression state.

[0034] Figure 6 This is a diagram showing the installation of the upper plate and locking bolts (before and after assembly).

[0035] Figure 7 This is a schematic diagram showing the installation of the locking bolt, sprocket spring, and movable pin.

[0036] Figure 8 This is a schematic diagram showing the installation of the bolts with holes, clamping bolts, upper plate, movable chain link, and lower plate.

[0037] Among them: 1-bolt with hole, 2-clamping bolt, 3-thread plug, 4-locking bolt, 41-bolt shaft, 5-upper plate, 51-spring groove, 6-movable pin, 7-sprocket spring, 71-pin hole, 72-spring hole, 8-movable chain link, 9-lower plate. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0039] As shown in the figure, an automatic timing tensioner sprocket for a diesel engine includes: a bolt with a hole 1, a clamping bolt 2, a threaded plug 3, a locking bolt 4, an upper plate 5, a movable pin 6, a sprocket spring 7, a movable chain link 8, and a lower plate 9. The threaded plug 3 and the locking bolt 4 are not present simultaneously; they have an assembly sequence. The locking bolt 4 is required when assembling the automatic tensioner sprocket itself. After the entire automatic tensioner sprocket is assembled onto the camshaft, the locking bolt 4 needs to be removed and replaced with a threaded plug. The details are as follows:

[0040] The bolt 1 with holes, preferably M14, is a hollow bolt with a length of 52 mm and an oil passage with a diameter of 6 mm, but this application is not limited thereto. The bolt 1 with holes is used to fix the automatic tensioning sprocket to the camshaft (not shown), and can introduce the oil in the camshaft into the automatic tensioning sprocket to provide tension to the automatic tensioning sprocket.

[0041] The clamping bolt 2 is preferably an M6 ordinary bolt with a length of 15mm, but this application is not limited to this. The purpose of the clamping bolt 2 is to fix the upper plate 5 and the lower plate 9 and prevent the movable chain link 8 from falling out of the upper plate 5 and the lower plate 9 when the bolt with hole 1 is not installed.

[0042] The threaded plug 3, preferably an M4 ordinary threaded plug with a length of 5mm, is not limited to this in this application. The threaded plug 3 is used to block the two threaded holes on the upper plate 5 to prevent oil from leaking out of the automatic tensioning sprocket.

[0043] The locking bolt 4 is preferably an M4 bolt with a thread length of 4.5 mm, but this application is not limited to this. The locking bolt 4 also has a pin with a diameter of 2(0, -0.1) mm and a length of 4.5 mm at its front end. The pin can mate with two small holes on the sprocket spring 7 with a diameter of 2(+0.1, 0) mm. The locking bolt 4 is required for the assembly process; it is used to lock the sprocket spring 7 to its maximum compression state, so that the movable chain links 8 form a minimum pitch circle diameter of 78.76 mm, facilitating the assembly of the automatic tensioning sprocket onto the camshaft.

[0044] The upper plate 5 has 26 limiting grooves, each 3.8(+0.1, 0) mm long, 2(+0.1, 0) mm wide, and 3(+0.1, 0) mm deep, for assembling the movable chain link 8. The movable chain link 8 has a limiting shaft, 3(0, -0.1) mm long, 2(0, -0.1) mm wide, and 3(0, -0.1) mm high, allowing the movable chain link 8 to slide freely radially within the limiting grooves. The pitch circle diameter of the movable chain link 8 is 78.96 mm; when sliding within the grooves, the minimum pitch circle diameter is 78.76 mm, and the maximum pitch circle diameter is 80.36 mm. The upper plate 5 also has a spring groove 51 with an inner diameter of 48.76 mm, a width of 2.8 mm, and a depth of 2 (+0.1, 0) mm. It is used to assemble the sprocket spring 7. When the sprocket spring 7 is in its ultimate compression state, its inner diameter is also 48.76 mm, but its width is 2 mm. Therefore, the sprocket spring 7 can deform in the spring groove 51.

[0045] The movable pin 6 is preferably a common cylindrical pin with a diameter of 5mm and a height of 9mm. The movable pin 6 is used to block the gap created by the sprocket spring 7 due to relaxation, preventing oil from leaking out of the automatic tensioning sprocket.

[0046] The sprocket spring 7 is a single-piece torsion spring with an inner diameter of 48.76 mm, a width of 2 mm, and a height of 9 (-0.1, 0) mm in its ultimate compression state. On one hand, it deforms itself, increasing its diameter and pushing the movable chain link 8 outward to provide tension to the system. On the other hand, it keeps the engine oil inside the automatic sprocket, maintaining the pressure difference between the inside and outside, so that the internal engine oil can further push the sprocket spring 7 to expand, further increasing the system tension.

[0047] The movable link 8 has the same tooth profile as the ordinary link. The movable link 8 is assembled in the limiting groove of the upper plate 5 and the lower plate 9. Its thickness is 5 (0, -0.1) mm, which is slightly lower than the gap 5 (+0.1, 0) between the upper plate 5 and the lower plate 9. Therefore, the movable link 8 can extend and retract radially in the groove.

[0048] The lower plate 9 has a similar structure to the upper plate 5, and has structures such as limiting grooves and spring grooves, which are used to lock some degrees of freedom of the movable chain link 8 and the sprocket spring 7.

[0049] An automatic timing tensioner sprocket for a diesel engine, with the following component assembly instructions:

[0050] (1) When assembling the camshaft sprocket, first use a tightening torque of 10±1Nm to screw the locking bolt 4 into the corresponding threaded hole in the upper plate 5 (e.g., Figure 6 As shown, the two ends of the arrow represent before and after assembly.

[0051] (2) Using a tooling fixture, insert the two small holes of the sprocket spring 7 with a diameter of 2 (+0.1, 0) mm into the thin shafts of the two locking bolts 4 with a diameter of 2 (0, -0.1), and keep the sprocket spring 7 in the corresponding spring groove 51 of the upper plate 5. At this time, the sprocket spring 7 is in the ultimate compression state (e.g., Figure 7 As shown, the arrows indicate the assembly direction.

[0052] (3) Next, insert the movable pin 6 with a diameter of 5 (0, -0.2) mm into the pin hole 71 in the sprocket spring 7. This pin hole 71 is not a closed machined hole in the circumferential direction. It is composed of two semi-circular holes with a diameter of 5 (+0.2, 0) and a break in the middle. When the sprocket spring 7 is compressed to its limit, the cross-section is exactly flush, forming a circular hole. When the spring is not subjected to external force and is freely stretched, there is a certain gap between the two semi-circular holes (e.g., Figure 7 As shown, the arrows indicate the assembly direction.

[0053] (4) Insert the limiting pin on the movable link 8 into the corresponding limiting groove on the upper plate 5. The limiting pin of the movable link 8 has a width of 2 (0, -0.1) and a length of 3 (0, -0.1). The limiting groove of the upper plate 5 has a width of 2 (+0.1, 0) and a length of 3.8 (+0.1, 0). The lower plate 9 also has a corresponding limiting groove. Similarly, align the lower plate 9 with the assembled movable link 8 and insert it. Then, use a torque of 10±1 Nm to screw the clamping bolt 2 into the outer side of the upper plate 5. At this time, the upper plate 5 and the lower plate 9 are connected by the clamping bolt 2. After assembly, since the thickness of the movable link 8 is 5 (0, -0.1) and the outer gap between the upper plate 5 and the lower plate 9 is 5 (0, +0.1), the movable link 8 has a degree of freedom in the radial direction in the corresponding limiting groove. The other degrees of freedom are locked (e.g., Figure 8 As shown, the arrows indicate the assembly direction.

[0054] (5) In a timing system with an automatic tensioning camshaft sprocket assembly, the tensioner, fixed rail, and moving rail are no longer needed. Therefore, first hang the chain on the automatic tensioning sprocket and crankshaft sprocket, then pass the bolt with hole 1 through the hole in the automatic tensioning sprocket and tighten it on the camshaft. Then remove the locking bolt 4. At this time, the sprocket spring 7 deforms and expands without the front pin of the locking bolt 4, pushing each movable chain link 8 to extend radially. At this time, the chain is tightened. Then screw the threaded plug 3 into the threaded hole of the original locking bolt 4.

[0055] Explanation of the working principle of this application:

[0056] Once assembled, the tension of the entire chain system is provided by the deformation of the internal sprocket spring 7 of the automatic tensioning sprocket. When the engine is started, the engine oil enters the automatic tensioning sprocket through the camshaft and the bolt with holes 1. At this time, there is a pressure difference of about 2 bar between the inner and outer sides of the sprocket spring 7, which will further push the sprocket spring 7 to expand and increase the tension of the system.

[0057] When the chain system is running, if the crankshaft speed suddenly increases, the tension on the tight side increases and the tension on the slack side decreases. The movable chain link 8 near the tight side will contract radially under the force, while the movable chain link 8 near the slack side will extend radially under the action of spring force and oil pressure. At this time, the automatic tensioning sprocket will have a small eccentricity, which changes the center distance between the two sprockets, making the tight side longer, reducing the tension on the tight side, and shortening the slack side, maintaining the system tension level, reducing the swing amplitude on both sides of the system, reducing wear, and improving NVH performance.

[0058] When the chain wears down and each link lengthens uniformly, the movable link 8 can extend under the action of spring force and oil pressure to compensate for the elongation of the link.

[0059] The key technical point of this invention lies in the structure of a retractable movable chain link + sprocket spring + introducing internal oil pressure into the sprocket, which enables the camshaft sprocket to have the functions of automatic tensioning, compensating for timing errors, reducing dynamic load, improving service life and reducing noise.

[0060] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various different choices and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A timing automatic tensioning sprocket for a diesel engine, characterized in that, include: A bolt with holes (1), which is a hollow bolt, is used to fix the automatic tensioning sprocket on the camshaft; The upper plate (5) and the lower plate (9) are both provided with a large circular hole in the center for the bolt (1) with holes to pass through. The upper end of the large circular hole is provided with a small circular hole for the clamping bolt (2) to pass through. The lower end of the large circular hole of the upper plate (5) is provided with a pair of threaded holes for the thread plug (3) or the locking bolt (4) to pass through. The inner surfaces of the upper plate (5) and the lower plate (9) are provided with spring grooves. The outer side of the spring groove is provided with limit grooves at equal intervals along the circumferential direction. The sprocket spring (7) is a single torsion spring, which is detachably installed in the spring groove of the upper plate (5). The lower side of the sprocket spring (7) is provided with a pin hole (71) for accommodating the movable pin (6). Spring holes (72) are symmetrically arranged on both sides of the pin hole (71). The movable link (8) is sandwiched in the limiting groove of the upper plate (5) and the lower plate (9), and its thickness is less than the gap between the upper plate (5) and the lower plate (9). The movable link (8) can freely extend and retract in the radial direction within the limiting groove. The movable pin (6) is used to block the gap created by the sprocket spring (7) due to relaxation, preventing oil from leaking from the automatic tensioning sprocket; During assembly, the two bolt shafts (41) at the end of the locking bolt (4) respectively cooperate with the two spring holes (72) to lock the sprocket spring (7) to the ultimate compression state, so that the movable chain link (8) forms the minimum pitch circle diameter, which facilitates the assembly of the automatic tensioning sprocket onto the camshaft; After assembly, remove the locking bolt (4) and use the threaded plug (3) to block the two threaded holes at the lower end of the large round hole of the upper plate (5) to prevent oil from leaking out of the automatic tensioning sprocket.

2. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The bolt with holes (1) is an M14 hollow bolt with a length of 52mm and an oil passage with a diameter of 6mm; the bolt with holes (1) is used to fix the automatic tensioning sprocket to the camshaft and can introduce the oil in the camshaft into the automatic tensioning sprocket to provide tension for the automatic tensioning sprocket.

3. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The clamping bolt (2) is an M6 ordinary bolt with a length of 15mm; the clamping bolt (2) can pass through the small round holes of the upper plate (5) and the lower plate (9) and fix them together to prevent the movable link (8) from falling out of the upper plate (5) and the lower plate (9) when the bolt with hole (1) is not installed.

4. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The thread plug (3) is an M4 ordinary thread plug with a length of 5mm.

5. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The locking bolt (4) is an M4 ordinary bolt with a thread length of 4.5mm.

6. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The upper plate (5) is provided with 26 limiting grooves, which are used to assemble movable chain links (8). The movable chain links (8) can slide freely in the radial direction within the limiting grooves. The upper plate (5) also has a spring groove (51), which is used to assemble the sprocket spring (7). The sprocket spring (7) can deform within the spring groove (51).

7. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The pin hole (71) consists of two semi-circular holes with a break in the middle. When the sprocket spring (7) is compressed to its limit, the cross-section is exactly flush, forming a circular pin hole. When the spring is not subjected to external force and is freely stretched, there is a gap between the two semi-circular holes.

8. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The movable pin (6) is a common cylindrical pin with a diameter of 5 mm and a height of 9 mm.

9. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The thickness of the movable link (8) is lower than the gap between the upper plate (5) and the lower plate (9) to ensure that the movable link (8) can extend and retract radially within the limiting groove.

10. The diesel engine timing automatic tensioning sprocket according to claim 1, characterized in that, The lower plate (9) is used to lock part of the degrees of freedom of the movable link (8) and the sprocket spring (7).

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