Diesel engine double overhead camshaft chain self-adaptive tensioning device

Abstract

A sliding cavity is formed in a shell, a compression spring is installed in the sliding cavity, a piston is installed in the sliding cavity in a sliding fit mode, and the piston is ejected outwards under the action of the compression spring and abuts against a chain guide plate. A plurality of annular ratchet grooves are formed in the extending end of the piston, the adjacent ratchet grooves are connected, the ratchet spring comprises matching sections arranged in pairs, the matching sections are provided with outwards-protruding arc-shaped clamping parts, the arc-shaped clamping parts are clamped in the ratchet grooves, and protruding limiting blocks are arranged on the outer side wall of the shell and located in U-shaped grooves of the corresponding U-shaped sections. The cam shaft chain tensioning device has the beneficial effects that the cam shaft chain can be effectively tensioned, the abnormal noise generated by the chain can be effectively avoided in the cold starting process, after the cam shaft chain extends, the cam shaft chain tensioning device can adapt to the change of the length of the cam shaft chain through jumping of the ratchet spring, the tensioning force of the cam shaft chain is guaranteed, and the service life of the cam shaft chain is prolonged. Synchronous operation of the chain wheel and the chain is guaranteed.

Description

Technical Field

[0001] This invention relates to the tensioning of camshaft chains, and more particularly to an adaptive tensioning device for the chain of a diesel engine double overhead camshaft. Background Technology

[0002] The engine uses a double overhead camshaft (DOHC) design, transmitting power via a chain to rotate the camshaft and ensure valve timing. During cold starts, the existing camshaft chain tensioner may not be filled with high-pressure oil in time, resulting in insufficient chain tension. This causes a "ticking" sound from the chain during cold starts, affecting engine quality. Furthermore, as engine mileage increases, the chain stretches, potentially leading to asynchronous operation between the chain and sprockets. This can cause valve timing errors, and in severe cases, render the entire engine unusable. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adaptive tensioning device for the chain of a diesel engine with double overhead camshafts.

[0004] The objective of this invention is achieved through the following technical solution: A diesel engine double overhead camshaft chain adaptive tensioning device, comprising a cylinder head, a camshaft chain, and a chain guide plate. The chain guide plate is rotatably mounted on the cylinder head, and the camshaft chain is mounted on the transmission mechanism of the cylinder head. It also includes an adaptive tensioner that presses against the chain guide plate and tensions the camshaft chain. The adaptive tensioner includes a housing, a ratchet spring, a piston, and a compression spring. The housing is mounted on the cylinder head and located on one side of the chain guide plate. A sliding cavity is provided inside the housing, and a compression spring is installed inside the sliding cavity. The piston is slidably mounted inside the sliding cavity. The piston is pushed outward by the compression spring and abuts against the chain guide plate. The extended end of the piston has several annular ratchet grooves, and adjacent ratchet grooves are connected. The ratchet spring includes a pair of mating sections. The mating sections have an outwardly protruding arc-shaped locking part, which is locked in the ratchet groove. The two ends of the two mating sections are connected by a U-shaped section, and the U-shaped section extends away from the extension direction of the piston. A protruding limiting block is provided on the outer wall of the housing. The limiting block is located in the U-shaped groove of the corresponding U-shaped section. The front end of the housing is symmetrically provided with arc-shaped protrusions. The arc-shaped protrusions have arc-shaped stops, and the outer side of the arc-shaped locking part is locked in the arc-shaped stops.

[0005] Optionally, two mounting ears are symmetrically arranged on the top of the housing. When a movable pin is transversely inserted through the two mounting ears, the movable pin abuts against the piston, causing the piston to be in a retracted state.

[0006] Optionally, the piston includes a cylinder, the inner cavity of which is a mounting cavity. A push rod is installed in the mounting cavity. The bottom end of a compression spring abuts against the bottom of a sliding cavity, and the top end of the compression spring is fitted onto the push rod and abuts against the stepped surface of the push rod.

[0007] Optionally, a one-way valve assembly is installed at the bottom of the mounting cavity, the bottom end of the compression spring abuts against the one-way valve assembly, an oil injection channel communicating with the one-way valve assembly is provided on the housing, and an oil passage communicating with the mounting cavity is provided on the top of the piston.

[0008] Optionally, the one-way valve assembly includes a valve seat with a raised ring. The valve seat also has an oil filling hole communicating with the inner cavity of the raised ring. The raised ring has several slots and an inwardly protruding claw at the top. A spring seat, a one-way valve spring, and a ball valve are installed inside the inner cavity of the raised ring. The top end of the one-way valve spring abuts against the spring seat, and the bottom end of the one-way valve spring abuts against the ball valve. The ball valve closes the oil filling hole under the action of the one-way valve spring.

[0009] Optionally, the housing is provided with a latch, which is connected to the cylinder head by a locking screw.

[0010] The present invention has the following advantages: The adaptive tensioning device of the present invention can effectively tension the camshaft chain, effectively solving the "ticking" noise emitted by the engine during cold start. Moreover, when the camshaft chain elongates, the ratchet spring can adapt to the change in the length of the camshaft chain through "tooth skipping", ensuring the tension of the camshaft chain. Even if the engine is started from a cold state, it can ensure that the sprocket and chain operate synchronously and will not cause timing misalignment or other problems. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 Schematic diagram of the adaptive tensioner Figure 1 ; Figure 3 Schematic diagram of the adaptive tensioner Figure 2 ; Figure 4 This is a cross-sectional schematic diagram of an adaptive tensioner; Figure 5 A schematic diagram of the structure in which the arc-shaped locking part is locked inside the arc-shaped stop; Figure 6 This is a schematic diagram of a ratchet spring. Figure 7 This is a schematic diagram of the piston structure; Figure 8 This is a schematic diagram of the one-way valve assembly. Figure 9 This is a cross-sectional schematic diagram of the one-way valve assembly; In the diagram, 100-adaptive tensioner, 200-cylinder head, 300-camshaft chain, 400-chain guide plate, 1-housing, 2-rattooth spring, 3-moving pin, 4-piston, 5-compression spring, 6-push rod, 7-one-way valve assembly, 8-limit block, 9-lock, 10-mounting ear, 11-oil injection channel, 12-sliding cavity, 13-arc stop, 21-U-shaped section, 22-fitting section, 23-arc-shaped locking part, 41-cylinder, 42-mounting cavity, 43-rattooth groove, 44-oil passage, 71-valve seat, 72-ball valve, 73-one-way valve spring, 74-spring seat, 75-convex ring, 76-grooved, 77-claw, 78-oil injection hole. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0013] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0015] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0016] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0017] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] like Figure 1 As shown, a diesel engine double overhead camshaft chain adaptive tensioning device includes a cylinder head 200, a camshaft chain 300, and a chain guide plate 400. The chain guide plate 400 is rotatably mounted on the cylinder head 200, and the camshaft chain 300 is mounted on the transmission mechanism of the cylinder head 200. In this embodiment, the installation of the chain guide plate 400 to the cylinder head 200, the installation of the transmission mechanism to the cylinder head 200, and the installation of the camshaft chain 300 are all prior art and are conventional technologies in diesel engines. In this embodiment, the adaptive tensioning device also includes an adaptive tensioner 100, which presses against the chain guide plate 400 and tensions the camshaft chain 300. Further, as... Figure 2 , Figure 3 and Figure 4 As shown, the adaptive tensioner 100 includes a housing 1, a ratchet spring 2, a piston 4, and a compression spring 5. The housing 1 is mounted on the cylinder head 200 and is located on one side of the chain guide plate 400. A sliding cavity 12 is provided inside the housing 1, and the compression spring 5 is installed inside the sliding cavity 12. The piston 4 is slidably mounted in the sliding cavity 12. Under the action of the compression spring 5, the piston 4 is pushed outward and abuts against the chain guide plate 400. The extended end of the piston 4 has several annular ratchet grooves 43, and adjacent ratchet grooves 43 are connected, such as... Figure 7As shown, the ratchet spring 2 includes a pair of mating sections 22, each with a protruding arc-shaped locking part 23 that engages within a ratchet groove 43. Both ends of the two mating sections 22 are connected by U-shaped sections 21, which extend away from the extension direction of the piston 4. A protruding limiting block 8 is provided on the outer wall of the housing 1, located within the U-shaped groove of the corresponding U-shaped section 21. In this embodiment, two mounting ears 10 are symmetrically arranged on the top of the housing 1. When a movable pin 3 is laterally inserted through the two mounting ears 10, the movable pin 3 abuts against the piston 4, causing the piston 4 to be in a retracted state. That is, when the adaptive tensioner 100 is not in use, the movable pin 3 is inserted through the mounting ears 10, thereby restricting the extension of the piston 4. At this time, the piston 4 is in a retracted state, i.e., the piston 4 is pressed inside the housing 1. Furthermore, the movable pin 3... Only one ratchet groove 43 is exposed at the top of the plug 4, and the arc-shaped locking part 23 is located in the exposed ratchet groove 43. At this time, the U-shaped segment 21 of the ratchet spring 2 does not contact the limiting block 8. The limiting block 8 is located in the U-shaped segment 21. There is a space for movement between the bottom of the limiting block 8 and the bottom of the U-shaped segment 21. When the adaptive tensioner 100 is installed on the cylinder head 200 and needs to be used, the movable pin 3 is taken out, and the piston 4 is pushed out under the action of the compression spring 5. At this time, the ratchet spring 2 also moves with the piston 4. Since the two ends of the housing 1 are provided with limiting blocks 8, when the U-shaped segment 21 of the ratchet spring 2 abuts against the limiting block 8 of the housing 1, the ratchet spring 2 no longer moves with the piston 4. At this time, there will be relative movement between the ratchet spring 2 and the ratchet groove 43 on the outer surface of the piston 4 until the camshaft chain 300 is in a tensioned state.

[0019] In this embodiment, as Figure 5As shown, the front end of the housing 1 is symmetrically provided with arc-shaped protrusions, and the arc-shaped protrusions are provided with arc-shaped stops 13. The outer side of the arc-shaped locking part 23 is locked in the arc-shaped stops 13. When the engine is first started and before the oil pressure is fully established or during the rapid acceleration of the engine, the camshaft chain 300 will apply force to the chain guide plate 400. Subsequently, the chain guide plate 400 will push the piston 4 to move backward. In this embodiment, the piston 4 is pushed forward. At this time, the ratchet spring 2 also moves backward with the piston 4. Since there are two symmetrical arc-shaped stops 13 on the front end face of the housing 1, when the ratchet spring 2 contacts the two symmetrical arc-shaped stops 13, the arc-shaped stops 13 lock the arc-shaped locking part 23 of the ratchet spring 2, so that the ratchet spring 2 and the piston 4 no longer move backward. This can prevent the bottom of the piston 4 from colliding with the bottom surface of the inner cavity of the housing 1 and producing a "clicking" sound. As engine running time or mileage increases, the chain will be stretched. At this time, under the combined action of compression spring 5 and oil pressure, piston 4 will move forward a short distance. When the moving distance is exactly the width of one ratchet groove 43, ratchet spring 2 will "skip teeth", that is, the arc-shaped locking part 23 of ratchet spring 2 will jump from the previous ratchet groove 43 to the next ratchet groove 43. After piston 4 moves forward, it will push the chain guide plate to move, thereby making the chain tensioned. Since the chain is stretched and will not shorten, when the chain is stretched, piston 4 is pushed out by compression spring 5 to adapt to the length of the chain, making the chain tensioned. When piston 4 is subjected to axial backward force, due to the existence of arc stop 13, piston 4 cannot retract, thus ensuring that the chain is always in a tensioned state.

[0020] In this embodiment, as Figure 6 As shown, the piston 4 includes a cylinder 41, the inner cavity of the cylinder 41 is a mounting cavity 42, a push rod 6 is installed in the mounting cavity 42, the bottom end of the compression spring 5 abuts against the bottom of the sliding cavity 12, the top end of the compression spring 5 is fitted onto the push rod 6 and abuts against the stepped surface of the push rod 6. Therefore, the elastic restoring force of the compression spring 5 acts on the push rod 6, and the push rod 6 transmits the elastic restoring force to the cylinder 41, thereby enabling the piston 4 to move forward under the action of the compression spring 5.

[0021] In this embodiment, as Figure 4As shown, a one-way valve assembly 7 is installed at the bottom of the mounting cavity 42. The bottom end of the compression spring 5 abuts against the one-way valve assembly 7. An oil injection channel 11 communicating with the one-way valve assembly 7 is provided on the housing 1. An oil passage hole 44 communicating with the mounting cavity 42 is provided on the top of the piston 4. Furthermore, the top of the push rod 6 is slotted. After the push rod 6 is installed, the oil in the mounting cavity 42 can be supplied to the oil passage hole 44 through the slot on the push rod 6. Therefore, after the oil enters the mounting cavity 42 through the one-way valve assembly 7, Under hydraulic pressure, engine oil can enter the surface of piston 4 through oil passage 44, thereby lubricating piston 4 and chain guide plate 400, preventing dry friction between piston 4 and chain guide plate 400, and extending the service life of piston 4 and chain guide plate 400. Furthermore, during engine shutdown, because the oil inlet of adaptive tensioner 100 has a one-way valve assembly 7, engine oil will not flow back from the cavity of adaptive tensioner 100 to the oil passage of cylinder head 200. The top slot of rod 6 and the oil passage hole 44 of piston 4 form the oil outlet. However, the slot and oil passage hole 44 are small in size, and it takes a while to unload the oil. Therefore, the piston 4 will maintain a high pressure state for a certain period of time, which will provide a certain pressure and cause piston 4 to slowly retract. When the arc-shaped locking part 23 of ratchet spring 2 is locked in the arc stop 13, piston 4 cannot retract. During this process, the amount of retraction of piston 4 is small and will not exceed the width of one ratchet groove 43, so that camshaft chain 300 is still in a tensioned state, but its tension is weakened. After the oil is drained, when the engine is started again, the chain is in a tensioned state, which ensures the transmission effect of the chain and avoids the "clicking" noise. When the oil pressure of high-pressure oil acts on piston 4 again, piston 4 will move forward a small distance again, which will provide a certain tension force for the camshaft chain 300, thereby increasing the tension of camshaft chain 300 and improving transmission efficiency.

[0022] In this embodiment, as Figure 8 and Figure 9 As shown, the one-way valve assembly includes a valve seat 71 with a raised ring 75. The valve seat 71 also has an oil filling hole 78 communicating with the inner cavity of the raised ring 75. The raised ring 75 has several slots 76 and an inwardly protruding claw 77 at its top. A spring seat 74, a one-way valve spring 73, and a ball valve 72 are installed inside the inner cavity of the raised ring 75. The top end of the one-way valve spring 73 abuts against the spring seat 74, and the bottom end of the one-way valve spring 73 abuts against the ball valve 72. The ball valve 72 closes the oil filling hole 78 under the action of the one-way valve spring 73. Because the raised ring 75 has several slots 76, during installation, the ball valve 72 and the spring seat 74 can be squeezed into the raised ring 75. During squeezing, the raised ring 75 expands outward and generates an elastic restoring force. After squeezing is complete, the raised ring 75 returns to its original position, thus preventing the ball valve 72 and the spring seat 74 from falling out of the raised ring 75.

[0023] In this embodiment, a latch 9 is provided on the housing, and the latch 9 is connected to the cylinder head by a locking screw. During installation, it is installed on the cylinder head by the locking screw.

[0024] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-adaptive tensioning device for a diesel engine double overhead camshaft chain, comprising a cylinder head, a camshaft chain, and a chain guide plate, wherein the chain guide plate is rotatably mounted on the cylinder head, and the camshaft chain is mounted on a transmission mechanism of the cylinder head, characterized in that: It also includes an adaptive tensioner that presses against the chain guide plate and tensions the camshaft chain. The adaptive tensioner includes a housing, a ratchet spring, a piston, and a compression spring. The housing is mounted on the cylinder head and is located on one side of the chain guide plate. A sliding cavity is provided inside the housing, and a compression spring is installed inside the sliding cavity. The piston is slidably mounted in the sliding cavity. Under the action of the compression spring, the piston pushes outward and abuts against the chain guide plate. The extended end of the piston has several annular ratchet teeth. The ratchet spring includes a pair of mating sections, each with a protruding arc-shaped locking portion that engages within the ratchet groove. Both ends of the two mating sections are connected by a U-shaped section extending away from the piston's extension direction. A protruding limiting block is provided on the outer wall of the housing, located within the U-shaped groove corresponding to the U-shaped section. A symmetrical arc-shaped protrusion is provided at the front end of the housing, with an arc-shaped stop opening on each protrusion. The outer side of the arc-shaped locking portion engages within the arc-shaped stop opening.

2. The adaptive tensioning device for a diesel engine double overhead camshaft chain according to claim 1, characterized in that: The top of the housing is symmetrically provided with two mounting ears. When a movable pin is transversely inserted through the two mounting ears, the movable pin abuts against the piston, causing the piston to be in a contracted state.

3. The adaptive tensioning device for a diesel engine double overhead camshaft chain according to claim 2, characterized in that: The piston includes a cylinder, the inner cavity of which is a mounting cavity. A push rod is installed in the mounting cavity. The bottom end of the compression spring abuts against the bottom of the sliding cavity, and the top end of the compression spring is fitted onto the push rod and abuts against the stepped surface of the push rod.

4. The adaptive tensioning device for a diesel engine double overhead camshaft chain according to claim 3, characterized in that: A one-way valve assembly is installed at the bottom of the mounting cavity, the bottom end of the compression spring abuts against the one-way valve assembly, an oil injection channel communicating with the one-way valve assembly is provided on the housing, and an oil passage communicating with the mounting cavity is provided at the top of the piston.

5. The adaptive tensioning device for a diesel engine double overhead camshaft chain according to claim 4, characterized in that: The one-way valve assembly includes a valve seat with a raised ring. The valve seat also has an oil injection hole communicating with the inner cavity of the raised ring. The raised ring has several slots and an inwardly protruding claw at its top. A spring seat, a one-way valve spring, and a ball valve are installed inside the inner cavity of the raised ring. The top end of the one-way valve spring abuts against the spring seat, and the bottom end of the one-way valve spring abuts against the ball valve. The ball valve closes the oil injection hole under the action of the one-way valve spring.

6. A self-adaptive tensioning device for a diesel engine double overhead camshaft chain according to any one of claims 1 to 5, characterized in that: The housing is provided with a latch, which is connected to the cylinder head by a locking screw.

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