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CN-122014815-A - Ball type hydraulic tensioner

CN122014815ACN 122014815 ACN122014815 ACN 122014815ACN-122014815-A

Abstract

The invention discloses a ball type hydraulic tensioner, which relates to the technical field of engine timing chain transmission and comprises a shell and balls, wherein a mounting cavity is formed in the shell, a plunger is slidably matched in the mounting cavity, a round table-shaped opening is formed in the top of the plunger, a limiting groove and a plurality of oil discharging grooves are formed in an oil control disc, the balls are arranged between the plunger and the limiting groove of the oil control disc and are clamped with the limiting groove and are positioned at the inner side of the round table-shaped opening of the plunger, a threaded hole is formed in the side wall of the plunger, and the end of the plunger abuts against the side wall of the oil control disc after machine meter bolts are screwed together to fix the positions of the balls. According to the invention, through the design of the balls, rolling contact between the balls and an external tensioning guide rail is realized, a dynamic oil film is formed on the rolling surface, sliding friction is converted into rolling friction, so that friction loss is reduced by more than 90%, the running smoothness of the system is improved, the abrasion and heating between the hydraulic tensioner and the guide rail are slowed down, and the NVH performance of the system is optimized.

Inventors

  • JIANG YUJIE
  • FENG ZENGMING
  • QIN ZIXIANG
  • LI XINGYU

Assignees

  • 吉林大学
  • 长春瑞百惠科技有限公司

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The ball type hydraulic tensioner is characterized by comprising a shell (1) and balls (3), wherein a mounting cavity (1.1) is formed in the shell (1), a plunger (2) is slidably matched in the mounting cavity (1.1), a round table-shaped opening is formed in the top of the plunger (2), an oil control disc (4) is coaxially arranged in an inner cavity of the plunger (2) and is limited by a machine meter bolt (5), an oil drain groove (4.1) and a limiting groove (4.2) are formed in the top surface of the oil control disc (4), the balls (3) are rotatably arranged between the plunger (2) and the limiting groove (4.2) of the oil control disc (4) and are located inside the round table-shaped opening of the plunger (2), and the portion, exposed out of the front end surface of the plunger (2), of the balls (3) are in rolling contact with a tensioning guide rail (10) and form dynamic oil films on the rolling surface.
  2. 2. The ball hydraulic tensioner according to claim 1, wherein the diameter of the ball (3) is 8mm, the height of the ball (3) exposed out of the front end face of the plunger (2) is 2mm, the ball (3) is tangential to the inner wall of the circular truncated cone-shaped opening of the plunger (2), and the radius of the circular truncated cone-shaped opening on the inner cavity side of the plunger (2) is larger than the radius on the outer cavity side.
  3. 3. The ball hydraulic tensioner of claim 1, wherein the oil drain grooves (4.1) are provided in a through groove structure, and the number of the oil drain grooves is a plurality of the oil drain grooves and are uniformly distributed circumferentially.
  4. 4. The ball type hydraulic tensioner of claim 3, wherein when the number of the oil drainage grooves (4.1) is three, a through groove structure with an included angle of 120 degrees is formed, the groove width of the through groove is 0.95mm, and the groove depth is 0.1mm.
  5. 5. The ball hydraulic tensioner according to claim 1, wherein the side wall of the plunger (2) is provided with a threaded hole, and the end of the machine bolt (5) abuts against the side wall of the oil control disc (4) after the machine bolt (5) is screwed in the threaded hole, so that the relative positions of the oil control disc (4) and the plunger (2) are fixed, and the positions of the balls (3) are limited.
  6. 6. The ball hydraulic tensioner according to claim 1 or 2, characterized in that the balls (3) are made of GCr15 bearing steel and subjected to induction hardening, and the surface hardness of the balls (3) is higher than HRC 55.
  7. 7. The ball hydraulic tensioner according to claim 1 or 2, wherein the rotational frequency of the ball (3) exceeds 100Hz when the rotational speed of the engine is not less than 3000 rpm.
  8. 8. The ball hydraulic tensioner of claim 1, wherein the housing (1) is further provided with a slot (1.6), a mounting pin (9) is inserted into the slot (1.6), the middle part of the mounting pin (9) abuts against the end face of the plunger (2) to axially pre-limit the plunger (2), the housing (1) is provided with a check spring (8), and the check spring (8) is tightly buckled on parallel grooves on the surface of the plunger (2) to prevent the plunger (2) from being excessively retracted into the housing (1) when working and prevent the plunger (2) from laterally shifting.
  9. 9. The ball type hydraulic tensioner according to claim 1, wherein an oil inlet (1.2) communicated with the installation cavity (1.1) is formed in the shell (1), an oil inlet cavity (1.3) is formed in the outer side of the shell (1), the oil inlet cavity (1.3) is communicated with the oil inlet (1.2), a one-way valve assembly (7) is arranged at a communication position between the bottom of the installation cavity (1.1) and the oil inlet (1.2), a plunger spring (6) is arranged between the one-way valve assembly (7) and the oil control disc (4), one end of the plunger spring (6) abuts against a front valve seat (7.1) of the one-way valve assembly (7), the other end of the plunger spring abuts against an end step surface of the oil control disc (4), and the plunger spring (6) applies elastic acting force to the plunger (2) through the oil control disc (4).
  10. 10. The ball-type hydraulic tensioner according to claim 3, wherein hydraulic oil flows between the plunger rear chamber and the plunger front chamber through the drain groove (4.1) and a gap between the plunger (2) and the oil control pan (4).

Description

Ball type hydraulic tensioner Technical Field The invention relates to the technical field of engine timing chain transmission, in particular to a ball type hydraulic tensioner. Background Hydraulic tensioners are widely used in engine timing chain systems for adaptively tensioning a timing chain to compensate for elongation of the chain due to wear. The internal hydraulic element forms oil pressure damping to absorb vibration in the transmission process, so that each part in the transmission system is reduced to be impacted, the chain is prevented from jumping and disengaging, transmission noise is reduced, accuracy and reliability of timing transmission are ensured, and stability of the chain transmission system is improved. Among the prior art hydraulic tensioners, for example, the technologies of CN217481875U (a piston type hydraulic tensioner), CN214092916U (an engine timing hydraulic tensioner), CN116146678B (a double spring type hydraulic tensioner), CN115076312a (an internal circulation type hydraulic tensioner) are all cylindrical plungers, and the end surfaces of the plungers are in direct contact with tensioning rails. Because of the periodic high speed variation of load and rotational speed, the hydraulic tensioner piston and tensioning rail also vibrate at high speed, and the contact surface position thereof can generate high-speed friction. Because the sliding friction coefficient between the plunger and the guide rail is high (usually 0.15-0.20), the generated high-speed friction not only increases energy loss, but also easily causes local overheating, so that the plunger and the guide rail surface are quickly worn, and further the material performance and the service life are affected. Therefore, a new ball hydraulic tensioner is needed to convert sliding friction into rolling friction by arranging rolling balls at the front end of a plunger, so that the friction characteristics are optimized fundamentally, the friction loss is reduced, the service life of a system is prolonged, and the NVH performance is improved. Disclosure of Invention The invention aims to provide a ball type hydraulic tensioner which converts sliding friction into rolling friction, optimizes friction characteristics from a root, and solves the problems of quick abrasion, large noise and the like caused by sliding friction of a traditional hydraulic tensioner and a tensioning guide rail. In order to solve the technical problems, the invention adopts the following technical scheme: A ball type hydraulic tensioner comprises a shell and balls, wherein an installation cavity is formed in the shell, a plunger is slidably matched in the installation cavity, a round table-shaped opening is formed in the top of the plunger, an oil control disc is coaxially arranged in an inner cavity of the plunger and is limited through a machine meter bolt, an oil drain groove and a limiting groove are formed in the top surface of the oil control disc, the balls are rotatably arranged between the plunger and the limiting groove of the oil control disc and are located on the inner side of the round table-shaped opening of the plunger, and the balls are exposed out of the front end face of the plunger, are in rolling contact with a tensioning guide rail and form a dynamic oil film on the rolling surface. Preferably, the diameter of the ball is 8mm, the height of the ball exposed out of the front end face of the plunger is 2mm, the ball is tangent to the inner wall of the circular truncated cone-shaped opening of the plunger, and the radius of the circular truncated cone-shaped opening, which is close to the inner cavity side of the plunger, is larger than the radius of the circular truncated cone-shaped opening, which is close to the outer cavity side of the plunger. Preferably, the oil drain groove is of a through groove structure, and the number of the oil drain grooves is multiple and uniformly distributed circumferentially. Preferably, when the number of the oil drain grooves is three, a through groove structure with an included angle of 120 degrees is formed, the groove width of the through groove is 0.95mm, and the groove depth is 0.1mm. Preferably, a threaded hole is formed in the side wall of the plunger, and after the machine rice bolt is screwed into the threaded hole, the end of the machine rice bolt abuts against the side wall of the oil control disc, so that the relative position of the oil control disc and the plunger is fixed, and the position of the ball is limited. Preferably, the balls are prepared from GCr15 bearing steel and subjected to high-frequency quenching treatment, and the surface hardness of the balls reaches more than HRC 55. Preferably, the ball rotation frequency exceeds 100Hz when the rotation speed of the engine is equal to or more than 3000 rpm. Preferably, the shell is further provided with a slot, a mounting pin is inserted into the slot, the middle part of the mounting pin is propped against the end face of