Ball type hydraulic tensioner

Abstract

The invention discloses a ball type hydraulic tensioner, and relates to the technical field of engine timing chain transmission, the ball type hydraulic tensioner comprises a shell and a ball, the shell is provided with a mounting cavity, a plunger is in sliding fit in the mounting cavity, and the top of the plunger is provided with a circular truncated cone-shaped opening; meanwhile, a limiting groove and a plurality of oil drainage grooves are formed in the oil control disc; the ball is arranged between the plunger and the limiting groove of the oil control disc, clamped with the limiting groove and located on the inner side of the circular-truncated-cone-shaped opening of the plunger. A threaded hole is formed in the side wall of the plunger, and after the machine-meter bolt is screwed, the end of the machine-meter bolt abuts against the side wall of the oil control disc to fix the position of the ball. Through the design of the balls, rolling contact between the balls and the external tensioning guide rail is achieved, a dynamic oil film is formed on the rolling surface, sliding friction is converted into rolling friction, friction loss is reduced by 90% or above, and therefore the running smoothness of a system is improved, abrasion and heating between the hydraulic tensioner and the guide rail are relieved, and the NVH performance of the system is optimized.

Description

Technical Field

[0001] This invention relates to the field of engine timing chain transmission technology, and more particularly to a ball-type hydraulic tensioner. Background Technology

[0002] Hydraulic tensioners are widely used in engine timing chain systems to adaptively tension the timing chain and compensate for chain elongation due to wear. They absorb vibrations during transmission by creating hydraulic damping through internal hydraulic components, reducing impact on components in the transmission system, preventing chain skipping and tooth loss, reducing transmission noise, ensuring the accuracy and reliability of timing transmission, and improving the stability of the chain drive system.

[0003] In existing authorized hydraulic tensioner technologies, such as CN217481875U (a piston-type hydraulic tensioner), CN214092916U (an engine timing hydraulic tensioner), CN116146678B (a double-spring type hydraulic tensioner), and CN115076312A (a hydraulic tensioner with an internal circulation structure), a cylindrical plunger is used, with its end face in direct contact with the tensioning guide rail. Due to the periodic high-speed changes in load and rotational speed, the hydraulic tensioner plunger and the tensioning guide rail also vibrate at high speed, resulting in high-speed friction at their contact surfaces. Because the sliding friction coefficient between the plunger and the guide rail is relatively high (typically 0.15-0.20), this high-speed friction not only increases energy loss but also easily leads to localized overheating, causing rapid wear on the surfaces of the plunger and guide rail, thus affecting material properties and service life.

[0004] Therefore, there is an urgent need for a brand-new ball-type hydraulic tensioner that converts sliding friction into rolling friction by setting rolling balls at the front end of the plunger, thereby optimizing friction characteristics from the root, reducing friction loss, extending system life, and improving NVH performance. Summary of the Invention

[0005] The purpose of this invention is to provide a ball-type hydraulic tensioner that converts sliding friction into rolling friction, thereby optimizing friction characteristics from the root and solving problems such as rapid wear and high noise caused by sliding friction in traditional hydraulic tensioners and tensioning guides.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A ball-type hydraulic tensioner includes a housing and balls. The housing has an installation cavity, and a plunger is slidably fitted inside the installation cavity. The top of the plunger has a frustum-shaped opening. An oil control plate is coaxially arranged in the inner cavity of the plunger and is limited by a nut bolt. The top surface of the oil control plate has an oil drain groove and a limiting groove. The balls are rotatably disposed between the plunger and the limiting groove of the oil control plate, and are located inside the frustum-shaped opening of the plunger. The portion of the balls exposed at the front end face of the plunger makes rolling contact with the tensioning guide rail and forms a dynamic oil film on the rolling surface.

[0007] Preferably, the diameter of the ball is 8mm, the height of the ball protruding from the front end face of the plunger is 2mm, and the ball is tangent to the inner wall of the frustum-shaped opening of the plunger; the radius of the frustum-shaped opening near the inner cavity of the plunger is greater than the radius near the outer cavity.

[0008] Preferably, the oil drain groove is a through groove structure, and there are multiple grooves that are evenly distributed around the circumference.

[0009] Preferably, when there are three oil drain grooves, they form a through groove structure with an included angle of 120°, the groove width is 0.95mm and the groove depth is 0.1mm.

[0010] Preferably, the plunger has a threaded hole on its side wall. After the nut is screwed into the threaded hole, its end abuts against the side wall of the oil control plate, so that the relative position of the oil control plate and the plunger is fixed, thereby limiting the position of the ball.

[0011] Preferably, the ball bearing is made of GCr15 bearing steel and subjected to high-frequency quenching treatment, and the surface hardness of the ball bearing reaches HRC55 or higher.

[0012] Preferably, when the engine speed is ≥3000rpm, the ball rotation frequency exceeds 100Hz.

[0013] Preferably, the housing is further provided with a slot in which a mounting pin is inserted. The middle part of the mounting pin abuts against the end face of the plunger to pre-limit the axial movement of the plunger. The housing is equipped with a check spring, which is fastened to a parallel groove on the surface of the plunger to prevent the plunger from retracting excessively into the housing during operation and to avoid lateral displacement of the plunger.

[0014] Preferably, the housing is provided with an oil inlet communicating with the mounting cavity, and an oil inlet chamber is provided on the outer side of the housing, and the oil inlet chamber is communicating with the oil inlet; a one-way valve assembly is provided at the communication between the bottom of the mounting cavity and the oil inlet, and a plunger spring is provided between the one-way valve assembly and the oil control plate. One end of the plunger spring abuts against the front valve seat of the one-way valve assembly, and the other end abuts against the end step surface of the oil control plate. The plunger spring applies an elastic force to the plunger through the oil control plate.

[0015] Preferably, the hydraulic oil flows between the rear cavity and the front cavity of the plunger through the drain groove and the gap between the plunger and the control plate.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: In an engine, due to the periodic high-speed changes in load and speed, the hydraulic tensioner plunger and tensioning guide also experience high-speed vibration. This invention, by incorporating balls at the top of the plunger, transforms the contact between the plunger and the external tensioning guide from the existing direct sliding fit to a rolling contact. This rolling contact avoids direct sliding wear between the plunger end face and the tensioning guide. Simultaneously, since the ball clearance is one of the oil drainage pathways of the hydraulic tensioner, a dynamic oil film forms on the surface when the balls roll relative to the guide, achieving self-lubrication. This converts the sliding friction (coefficient of friction 0.15-0.20) between the plunger and the tensioning guide into rolling friction (coefficient of friction 0.01-0.02), reducing friction loss by over 90% and significantly improving energy efficiency while minimizing wear.

[0017] Furthermore, the low-friction coefficient rolling contact design significantly reduces frictional heat generation, effectively avoiding the local overheating problem caused by sliding friction in traditional structures, and preventing high temperatures from affecting the material properties of components. At the same time, rolling friction significantly reduces vibration and abnormal noise during transmission, optimizes the NVH (noise, vibration, and harshness) performance of the engine timing chain drive system, and improves the smoothness and stability of system operation. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a three-dimensional structural diagram of the ball-type hydraulic tensioner of the present invention; Figure 2 This is a three-dimensional structural diagram of the ball-type hydraulic tensioner of the present invention from another angle; Figure 3 This is a half-sectional schematic diagram of the ball-type hydraulic tensioner of the present invention; Figure 4 This is a schematic diagram showing the contact between the hydraulic tensioner and the tensioning guide rail of the present invention; Figure 5This is a schematic diagram of the oil control disc of the present invention; Figure 6 This is a schematic diagram showing the positional relationship between the ball bearing, oil control disc, and plunger spring of the present invention. Figure 7 This is a schematic diagram of the plunger structure of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1. Housing; 1.1. Mounting cavity; 1.2. Oil inlet; 1.3. Oil inlet chamber; 1.4. First mounting ear; 1.5. Second mounting ear; 1.6. Slot; 1.7. Limiting boss; 2. Plunger; 3. Ball bearing; 4. Oil control plate; 4.1. Oil drain groove; 4.2. Limiting groove; 5. Measuring bolt; 6. Plunger spring; 7. Check valve; 7.1. Front valve seat; 7.2. Rear valve seat; 7.3. Valve ball; 8. Check spring; 9. Mounting pin; 10. Tensioning guide rail. Detailed Implementation

[0021] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] like Figure 1-7 As shown, a ball-type hydraulic tensioner includes a housing 1 and balls 3. The housing 1 has an installation cavity 1.1, in which a plunger 2 is slidably fitted. The top of the plunger 2 has a frustum-shaped opening. An oil control plate 4 is coaxially arranged in the inner cavity of the plunger 2 and is limited by a nut bolt 5. The top surface of the oil control plate 4 has an oil drain groove 4.1 and a limiting groove 4.2. The balls 3 are rotatably disposed between the plunger 2 and the limiting groove 4.2 of the oil control plate 4, and are located inside the frustum-shaped opening of the plunger 2. The portion of the balls 3 exposed at the front end face of the plunger 2 rolls in contact with the tensioning guide rail 10 and forms a dynamic oil film on the rolling surface.

[0023] Specifically, the diameter of the ball bearing 3 is 8mm, the height of the ball bearing 3 protruding from the front end face of the plunger 2 is 2mm, and the ball bearing 3 is tangent to the inner wall of the frustum-shaped opening of the plunger 2; the radius of the frustum-shaped opening near the inner cavity of the plunger 2 is larger than the radius near the outer cavity. When the external chain or belt is slack or tensioned, the ball bearing 3 will generate rolling friction with the external tensioning guide, avoiding direct sliding wear between the plunger 2 and the external tensioning guide. Furthermore, the ball bearing 3 is in direct contact with the hydraulic oil inside the plunger, further achieving lubrication between it and the external tensioning guide during rolling, optimizing the system's NVH performance, extending the service life of components, and reducing the operating cost of the timing chain system.

[0024] like Figure 5 ,6 As shown, the oil drain grooves 4.1 are configured as through grooves, and there are multiple grooves evenly distributed around the circumference. When there are three oil drain grooves 4.1, they form a through groove structure with an included angle of 120°. The width of the through groove is 0.95 mm and the depth is 0.1 mm. In use, hydraulic oil flows between the rear cavity and the front cavity of the plunger through the oil drain grooves 4.1 and the gap between the plunger 2 and the oil control plate 4. The oil drain grooves 4.1 allow the oil to flow in the front and rear cavities of the plunger. When the ball bearing 3 rolls, the oil can flow through the oil drain grooves 4.1 into the limiting groove 4.2 and the plunger cavity, thereby ensuring the lubrication of the ball bearing 3. The oil can also be exchanged with the outside through the limiting groove 4.2. It is evident that the design of the drain groove not only enables the smooth flow of hydraulic oil between the front and rear chambers of the plunger, providing hydraulic support for plunger extension and retraction, but also provides continuous lubrication for ball rolling. At the same time, the hydraulic oil can be exchanged with the outside through the drain groove and the limiting groove, preventing impurities from accumulating at the ball mating positions, ensuring the smoothness of ball rolling, and further improving the working reliability of the components.

[0025] like Figure 3 As shown, a threaded hole is provided on the side wall of the plunger 2. After the grommet 5 is screwed into the threaded hole, its end abuts against the side wall of the oil control plate 4, thereby fixing the relative position of the oil control plate 4 and the plunger 2, and thus limiting the position of the ball 3. Specifically, the grommet 5 is preferably M1.6. In particular, the oil control plate is fixed by the grommet, and the position of the ball is limited by the limiting groove, so that the ball does not deviate or fall off during operation, ensuring that the tension force on the tension guide is continuously and stably applied; effectively avoiding the tension force fluctuation problem caused by wear in traditional structures, ensuring the transmission accuracy of the engine timing chain, preventing chain skipping, tooth loss, loosening or falling off, and ensuring the reliable operation of the engine timing system.

[0026] Specifically, the ball bearing 3 is made of GCr15 bearing steel and undergoes high-frequency quenching treatment, achieving a surface hardness of HRC55 or higher; the oil control plate 4 is preferably made of PA66 engineering plastic. The ball bearings, oil control plate, and other components are precisely designed, with material selection considering both hardness and wear resistance. The processing and assembly processes are simple, making them highly valuable for practical application and promotion.

[0027] Specifically, since the crankshaft of this engine generates two excitations per revolution, when the engine speed is ≥3000rpm, the rotation frequency of the ball bearing 3 exceeds 100Hz, which can significantly reduce the coefficient of friction and wear, and play a role in buffering impact, reducing noise and vibration.

[0028] Specifically, the housing 1 is provided with a slot 1.6, into which a mounting pin 9 is inserted. The middle part of the mounting pin 9 abuts against the end face of the plunger 2, pre-limiting the axial movement of the plunger 2. After the mounting pin 9 is pulled out, the plunger 2 will pop out of the mounting cavity 1.1 under the action of the plunger spring 6. Since there is a gap between the plunger 2 and the housing 1, a check spring 8 is provided on the housing 1. The check spring 8 is tightly fastened to the parallel groove on the surface of the plunger 2 to prevent the plunger 2 from retracting excessively into the housing 1 during operation and to prevent the plunger 2 from shifting laterally. Specifically, the check spring 8 is U-shaped, with the middle section of the U-shape tightly fastened to the parallel groove of the plunger 2 for locking and positioning, and the two ends of the U-shape fitted onto the limiting bosses 1.7 on both sides of the housing 1.

[0029] like Figure 1-2 As shown, the housing 1 is provided with an oil inlet 1.2 that communicates with the mounting cavity 1.1. An oil inlet cavity 1.3 is provided on the outer side of the housing 1, and the oil inlet cavity 1.3 communicates with the oil inlet 1.2. When in use, external hydraulic oil flows into the oil inlet 1.2 through the oil inlet cavity 1.3 and then into the mounting cavity 1.1, causing the plunger to axially extend and retract within the mounting cavity 1.1 under hydraulic action. A ball bearing 3 is provided at its top end to contact the external guide rail, thereby tensioning the external tension guide rail.

[0030] like Figure 3 As shown, a one-way valve assembly 7 is provided at the connection between the bottom of the mounting cavity 1.1 and the oil inlet 1.2. A plunger spring 6 is provided between the one-way valve assembly 7 and the oil control plate 4. One end of the plunger spring 6 abuts against the front valve seat 7.1 of the one-way valve assembly 7, and the other end abuts against the end step surface of the oil control plate 4. The plunger spring 6 applies an elastic force to the plunger 2 through the oil control plate 4. In use, when the external chain or belt is loosened or tightened, the tension force is transmitted to the oil control plate 4 through the ball bearing 3, thereby changing the spring force of the plunger spring 6. At the same time, it will also affect the hydraulic oil pressure in the plunger cavity, thereby controlling the opening and closing of the one-way valve assembly 7.

[0031] Specifically, the one-way valve assembly 7 includes a front valve seat 7.1, a rear valve seat 7.2, and a valve ball 7.3. The front valve seat 7.1 is fixed to the end of the mounting cavity 1.1, the rear valve seat 7.2 is disposed inside the front valve seat 7.1, and the valve ball 7.3 is disposed between the front valve seat 7.1 and the rear valve seat 7.2, for realizing one-way flow of hydraulic oil.

[0032] The specific usage process is as follows: when the plunger 2 extends, the one-way valve 7 opens, and the oil flows into the mounting cavity 1.1 through the oil supply line; when the plunger 2 is compressed, the pressure in the mounting cavity 1.1 increases and exceeds the oil supply pressure, the one-way valve 7 closes, and the mounting cavity 1.1 forms a closed environment. At this time, the oil can only flow out through the leakage gap between the plunger 2 and the housing 1.

[0033] When the chain or belt slackens, the plunger spring 6 and the hydraulic fluid push the plunger 2 outward, reducing the hydraulic oil pressure in the mounting cavity 1.1. At this time, the high-pressure hydraulic oil pushes the valve ball 7.3 to move within the front valve seat 7.1, the check valve 7 opens, and the piston 2 moves outward, tightening the guide rail through the front ball 3, thus achieving tension compensation of the timing system.

[0034] When the chain or belt is subjected to a sudden impact and the tension increases sharply, the plunger spring 6 is compressed, the valve ball 7.3 is pressed against the valve seat 7.2, and the one-way valve 7 is closed. Some hydraulic oil can only flow out through the leakage gap. The hydraulic oil generates a large damping force to absorb the impact force on the chain or belt, effectively buffering the impact and preventing the chain or belt from breaking due to overload, thereby protecting the entire transmission system.

[0035] Furthermore, the housing 1 is integrally formed with mounting ears for fixed connection with the transmission system frame. Specifically, the mounting ears include a first mounting ear 1.4 and a second mounting ear 1.5, which are respectively located on both sides. One mounting ear has a circular through hole for easy positioning, and the other mounting ear has an oblong through hole to provide adjustment space for easy installation. In particular, the integrally formed mounting ears can achieve quick fixed installation with the existing transmission system frame without requiring significant modification to the overall structure of the transmission system, demonstrating strong adaptability.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0037] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A ball-type hydraulic tensioner, characterized in that: The device includes a housing (1) and a ball bearing (3). The housing (1) has an installation cavity (1.1). A plunger (2) is slidably fitted in the installation cavity (1.1). The top of the plunger (2) has a frustum-shaped opening. An oil control plate (4) is coaxially arranged in the inner cavity of the plunger (2) and is limited by a nut bolt (5). An oil drain groove (4.1) and a limiting groove (4.2) are provided on the top surface of the oil control plate (4). The ball bearing (3) is rotatably arranged between the plunger (2) and the limiting groove (4.2) of the oil control plate (4) and is located inside the frustum-shaped opening of the plunger (2). The part of the ball bearing (3) exposed on the front end face of the plunger (2) rolls in contact with the tension guide rail (10) and forms a dynamic oil film on the rolling surface.

2. The ball-type hydraulic tensioner according to claim 1, characterized in that: The diameter of the ball (3) is 8mm, the height of the ball (3) exposed on the front end face of the plunger (2) is 2mm, and the ball (3) is tangent to the inner wall of the frustum-shaped opening of the plunger (2); the radius of the frustum-shaped opening near the inner cavity of the plunger (2) is greater than the radius near the outer cavity.

3. The ball-type hydraulic tensioner according to claim 1, characterized in that: The oil drain groove (4.1) is designed as a through groove structure, and there are multiple grooves that are evenly distributed around the circumference.

4. The ball-type hydraulic tensioner according to claim 3, characterized in that: When there are three oil drain grooves (4.1), they form a through groove structure with an included angle of 120°. The width of the through groove is 0.95 mm and the depth is 0.1 mm.

5. The ball-type hydraulic tensioner according to claim 1, characterized in that: The plunger (2) has a threaded hole on its side wall. After the machine bolt (5) is screwed into the threaded hole, its end abuts against the side wall of the oil control plate (4), so that the relative position of the oil control plate (4) and the plunger (2) is fixed, thereby limiting the position of the ball (3).

6. The ball-type hydraulic tensioner according to claim 1 or 2, characterized in that: The ball (3) is made of GCr15 bearing steel and is subjected to high frequency quenching treatment. The surface hardness of the ball (3) reaches HRC55 or above.

7. The ball-type hydraulic tensioner according to claim 1 or 2, characterized in that: When the engine speed is ≥3000rpm, the rotation frequency of the ball (3) exceeds 100Hz.

8. The ball-type hydraulic tensioner according to claim 1, characterized in that: The housing (1) is also provided with a slot (1.6), in which a mounting pin (9) is inserted. The middle part of the mounting pin (9) abuts against the end face of the plunger (2) to pre-limit the axial movement of the plunger (2). The housing (1) is equipped with a check spring (8), which is fastened to the parallel groove on the surface of the plunger (2) to prevent the plunger (2) from retracting excessively into the housing (1) during operation and to prevent the plunger (2) from lateral displacement.

9. The ball-type hydraulic tensioner according to claim 1, characterized in that: The housing (1) is provided with an oil inlet (1.2) that communicates with the mounting cavity (1.1). An oil inlet cavity (1.3) is provided on the outside of the housing (1), and the oil inlet cavity (1.3) communicates with the oil inlet (1.2). A one-way valve assembly (7) is provided at the connection between the bottom of the mounting cavity (1.1) and the oil inlet (1.2). A plunger spring (6) is provided between the one-way valve assembly (7) and the oil control plate (4). One end of the plunger spring (6) abuts against the front valve seat (7.1) of the one-way valve assembly (7), and the other end abuts against the end step surface of the oil control plate (4). The plunger spring (6) applies an elastic force to the plunger (2) through the oil control plate (4).

10. The ball-type hydraulic tensioner according to claim 3, characterized in that: Hydraulic oil flows between the rear cavity and front cavity of the plunger through the drain groove (4.1) and the gap between the plunger (2) and the control plate (4).

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