Hydraulic automatic tensioner and engine system

Abstract

The utility model discloses a hydraulic automatic tensioner and an engine system.The tensioner comprises a shell, a first barrel, a second barrel, a first oil drainage channel and a second oil drainage channel, the first barrel is sleeved with the shell, the second barrel is used for pressing a chain, and the first barrel is sleeved with the second barrel; the first oil drainage channel and the second oil drainage channel are used for communicating the first cavity with the outside, the first oil drainage channel communicates with the outside all the time, and the second oil drainage channel is provided with a communicating station and a disconnecting station; the second oil drainage channel comprises a first section part, the first section part penetrates through the cylinder wall of the first cylinder body, so that a first opening part is formed in the first cavity, and a second opening part is formed in the peripheral wall of the first cylinder body; and when the second barrel body moves in the axial direction, the second opening part can be blocked or opened, so that the second oil drainage channel is switched between the communication station and the disconnection station.

Description

Technical Field

[0001] The present application relates to the field of engine technology, and in particular to a hydraulic automatic tensioner and an engine system. Background Art

[0002] As the core component of the engine chain system, the hydraulic automatic tensioner is responsible for tensioning the chain, compensating for chain wear and elongation, suppressing chain vibration, and reducing system dynamic impact. Since the working conditions and load levels of the chain system vary greatly when the engine is in different speed ranges and operating conditions, the hydraulic stiffness of the traditional hydraulic automatic tensioner is fixed, so its hydraulic stiffness must be large enough to ensure that the chain can be effectively tightened under high engine speed, high load and certain extreme working conditions.

[0003] However, since the working conditions and load levels of the chain system vary greatly when the engine is in different speed ranges and operating conditions, such a tensioner design is not optimal for the medium and low speed load conditions that are more commonly used by users. In the medium and low speed parts that are more commonly used by users, the tensioner's stiffness is too large, which will increase the friction loss of the chain system and make too much noise.

[0004] In view of this, there is an urgent need to provide a technical solution that can ensure that the engine can effectively tighten the chain at high speed and high load, and at the same time can reduce the friction loss of the chain system and reduce the noise of the chain system when the engine is working at medium and low speeds. Utility Model Content

[0005] One purpose of the present application is to provide a new technical solution for a hydraulic automatic tensioner and an engine system, by improving the structure of the hydraulic automatic tensioner to ensure that the engine high speed and high load can effectively tighten the chain, and at the same time, when the engine is operating at medium and low speeds, it can reduce the friction loss of the chain system and reduce the noise of the chain system.

[0006] In one aspect of the present application, a hydraulic automatic tensioner is provided, the tensioner comprising a housing, a first cylinder, a second cylinder, a first oil leakage channel and a second oil leakage channel, the housing is sleeved on the first cylinder and encloses a first cavity with the first cylinder, the first cavity is used to contain engine oil from the engine; the second cylinder is used to compress the chain, the second cylinder is sleeved on the first cylinder, and the second cylinder can move axially relative to the first cylinder under the action of the chain; the first oil leakage channel and the second oil leakage channel are used to connect the first cavity with the outside, the first oil leakage channel is always connected with the outside, and the second oil leakage channel has a connecting position and a disconnecting position; the second oil leakage channel comprises a first section, the first section passes through the cylinder wall of the first cylinder to form a first opening in the first cavity, and a second opening is formed on the outer peripheral wall of the first cylinder; when the second cylinder moves axially, it can block the second opening or open the second opening to switch the second oil leakage channel to the connecting position and the disconnecting position.

[0007] By adopting the embodiment of the present application, during the operation of the chain system of the engine, as the dynamic tension of the chain changes, the chain tension acts on the second elastic member through the second cylinder. At this time, the second elastic member transmits the force of the chain to the first cylinder so that the first cylinder forms a movement trend in the same direction as the second cylinder.

[0008] However, since the first cylinder is subjected to the combined thrust from the hydraulic pressure in the first chamber and the first elastic member, the thrust is applied to the second elastic member through the first cylinder. At this time, the second elastic member will be compressed, so that the second cylinder will be displaced axially relative to the first cylinder in the direction of the compression of the second elastic member. When the engine is running at high speed and high load, the chain load and tension change greatly, and the second cylinder will also be displaced greatly. When the displacement meets the set threshold, the second cylinder will close the second oil leakage channel. At this time, the high-pressure oil in the first chamber can only be discharged from the first oil leakage channel in the normally open state. It is equivalent to reducing the oil leakage speed of the first chamber. At this time, the oil in the first chamber will produce a strong resistance support to the first cylinder, and the tensioner works in a high damping mode. Therefore, when the engine is working at high speed and high load, even if the tension of the chain changes greatly, the tensioner can effectively tighten the chain. At this time, the stiffness of the tensioner is large, which can keep the chain system running stably.

[0009] When the engine is operating at medium and low speeds, the chain is working stably, and the tension does not change much. The displacement of the second cylinder is small at this time and does not reach the set threshold. The second oil drain channel is in a connected state, and the high-pressure engine oil in the first chamber can be discharged faster from the first oil drain channel and the second oil drain channel at the same time. This effectively reduces the damping of the engine oil in the first chamber on the chain tension, and the tensioner works in a low damping mode. At this time, the tensioner has a small stiffness, that is, the tensioner is relatively soft, which can significantly reduce the dynamic tension of the chain at this time, thereby reducing the friction loss of the chain system, reducing the noise of the chain system, and improving its reliability. Optionally, the first cylinder is axially provided with a first end and a second end relative to each other, and the second cylinder is sleeved on the second end.

[0010] Optionally, the inner wall of the second cylinder is in contact with the second mouth to block the second mouth, or is separated from the second mouth to open the second mouth.

[0011] Optionally, the first end is built into the housing, the second end forms a gap with the housing in a radial direction, the gap is communicated with the outside, and the second opening is located at a portion of the first cylinder that encloses the gap;

[0012] The second cylinder moves axially in the gap to open or block the second opening.

[0013] Optionally, the first end is open, the second end is closed, the second cylinder and the second end form a second cavity, and the first cavity is spaced from the second cavity;

[0014] Optionally, the inner wall of the second cylinder is provided with a first oil groove which is always connected with the second opening, and the first cylinder is further provided with a second oil groove which is provided at the side where the second opening is located, and the first oil groove is always connected with the second oil groove;

[0015] The first oil groove is connected to the second oil groove to ensure that the first oil groove can still be connected to the second opening when the second cylinder rotates; an annular groove is circumferentially provided on the outer wall of the second end of the first cylinder corresponding to the position of the second opening to serve as the second oil groove;

[0016] At the disconnection station, the outer wall of the first cylinder seals the first oil groove;

[0017] At the connecting station, the first oil groove is connected to the second cavity.

[0018] Optionally, the second cylinder is provided with an oil outlet, and the oil outlet is used to discharge the oil and air in the second cavity;

[0019] The second cylinder is used to abut against the tensioning rail to compress the chain, and the oil outlet is arranged at the position where the second cylinder contacts the tensioning rail.

[0020] Optionally, the first oil drain channel is provided between the first cylinder and the outer shell, and structurally, the first cavity can be connected with the outside through an appropriate fitting gap or by providing a separate narrow groove.

[0021] Optionally, the shell is configured with an oil inlet, and the tensioner also includes a one-way valve arranged at the oil inlet, and the valve port of the one-way valve is connected to the oil inlet; the hydraulic automatic tensioner also includes an oil return channel, and a groove is provided in the contact area between the outside of the one-way valve and the shell to form a bypass connection between the first chamber and the oil inlet to serve as the oil return channel.

[0022] The oil from the engine can freely enter the interior of the housing from the oil inlet through the one-way valve. On the contrary, the one-way valve prevents the oil inside the housing from flowing back to the oil inlet. Similar to the function of the first oil drain channel, a narrow groove or a labyrinth-shaped groove can be provided on the outer wall and bottom surface where the one-way valve contacts the housing to establish a fixed bypass connection between the first chamber and the oil inlet, thereby forming the return oil channel. The difference between the return oil channel and the first oil drain channel is that the oil flowing out of the first chamber through the first oil drain channel will be directly discharged to the outside of the tensioner, while the return oil channel allows the oil in the first chamber to flow back to the oil inlet, that is, to be recycled inside the tensioner, thereby reducing the oil consumption of the tensioner.

[0023] Optionally, it further comprises a filling part, the filling part is arranged in the first cavity, and the filling part is connected to one end of the first cylinder body close to the second cylinder body;

[0024] The second oil leakage passage also includes a second section having a throttling effect. The second section is a third oil groove opened in the filling portion. One end of the third oil groove is connected to the first cavity, and the other end is connected to the first port.

[0025] Optionally, the third oil groove extends in a spiral shape.

[0026] In another aspect of the present application, an engine system is provided. The engine system includes a chain and the above-mentioned hydraulic automatic tensioner, wherein the hydraulic automatic tensioner presses the chain.

[0027] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0029] Figure 1 is a schematic diagram of the coordination between the tensioner and the chain in the embodiment of the present application;

[0030] Figure 2 is a working principle diagram of the tensioner in the embodiment of the present application;

[0031] Figure 3 is a structural schematic diagram of the tensioner in the first embodiment of the present application in the connection position;

[0032] Figure 4 yes Figure 3 A magnified schematic diagram of the local structure;

[0033] Figure 5 is a structural schematic diagram of the tensioner in the first embodiment of the present application in the disconnected position;

[0034] Figure 6 yes Figure 5 A magnified schematic diagram of the local structure;

[0035] Figure 7 is a structural schematic diagram of the tensioner in the second embodiment of the present application in the connection position;

[0036] Figure 8 It is a structural schematic diagram of the tensioner in the second embodiment of the present application in the disconnected position.

[0037] Description of reference numerals:

[0038] 1. Shell; 11. Clearance; 12. Oil inlet; 13. Check valve; 14. Oil return channel;

[0039] 2. first cylinder; 21. first end; 22. second end; 23. first elastic member; 24. flange;

[0040] 3. First chamber; 31. First oil drain channel;

[0041] 4. second cylinder; 41. second elastic member; 42. second cavity; 43. oil outlet;

[0042] 5. Filling part; 51. Third oil tank;

[0043] 6. Second oil drain channel; 61. First section; 61a. First port; 61b. Second port; 62. First oil groove; 62a. Oil drain port; 63. Second section; 64. Second oil groove;

[0044] 7. Tensioner;

[0045] 8. Tension rail;

[0046] 9. Chain. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] In some embodiments of the present application, Figure 1 and Figure 2 As shown, a hydraulic automatic tensioner 7 is provided, which includes a housing 1, a first cylinder 2, and a second cylinder 4. The housing 1 is sleeved on the first cylinder 2 and encloses a first chamber 3 with the first cylinder 2. The first chamber 3 is used to contain oil from the engine. When the vehicle engine is running, the oil from the engine enters the first chamber 3 through the oil inlet 12 opened in the housing 1 via the one-way valve 13 and fills the first chamber 3 to form a high-pressure chamber.

[0049] A first elastic member 23 is further provided between the first cylinder 2 and the outer shell 1 . The first cylinder 2 and the outer shell 1 are elastically connected via the first elastic member 23 . The first elastic member 23 is used to provide a rebound force for the first cylinder 2 .

[0050] like Figure 3 As shown, the first cylinder 2 has a first end 21 and a second end 22, the first end 21 is an open end, and the second end 22 is a closed end. The first end 21 of the first cylinder 2 is inserted into the outer shell 1, and defines a first cavity 3 with the inner wall of the outer shell 1. The oil inlet 12 is opened on one side of the outer shell 1. The oil inlet 12 is also connected to a one-way valve 13 to prevent the oil in the first cavity 3 from flowing back. In order to adjust the effective volume of the first cavity 3, a corresponding filling part 5 can be added to the first cylinder 2, and the filling part 5 is connected to the second end 22. A first elastic member 23 is arranged in the first cavity 3, and the two ends of the first elastic member 23 are respectively in contact with the outer shell 1 (or the one-way valve 13) and the second end 22 (or the filling part 5) of the first cylinder 2.

[0051] like Figure 3 As shown, a flange 24 is formed by axially protruding from the edge of the second end 22 of the first cylinder 2 away from the first cavity 3 .

[0052] The second cylinder 4 is used to press against the tension rail 8, thereby compressing the chain 9, and the second cylinder 4 is sleeved on the second end 22 of the first cylinder 2 and the outer side of the flange 24. The outer wall of the second cylinder 4 maintains a certain gap with the inner wall of the outer shell 1, and the inner wall of the second cylinder 4 matches the outer peripheral wall of the second end 22 of the first cylinder 2 and the flange 24, and the second cylinder 4 can move axially relative to the first cylinder 2.

[0053] Thus, a second cavity 42 is formed between the second end 22 of the first cylinder 2, the flange 24 and the second cylinder 4. A second elastic member 41 is disposed in the second cavity 42, one end of the second elastic member 41 extends into the flange 24 to abut against the end surface of the second end 22 of the first cylinder 2, and the other end extends out of the flange 24 to abut against the bottom end of the second cylinder 4. Under the action of the chain 9, the second cylinder 4 can move axially relative to the first cylinder 2 and compress the second elastic member 41.

[0054] That is to say, Figure 1 and Figure 2 As shown, the first cylinder 2 pushes the second cylinder 4 axially through the second elastic member 41 under the combined action of the first elastic member 23 and the hydraulic pressure in the first chamber 3. The second cylinder 4 can directly press the chain 9, or the second cylinder 4 can be connected to the tensioning rail 8 in a transmission manner, and the second cylinder 4 pushes the tensioning rail 8 axially to press the chain 9.

[0055] See also Figure 2 and Figure 3 The tensioner 7 includes a first oil drain channel 31, a second oil drain channel 6 and an oil return channel 14. The first oil drain channel 31 and the second oil drain channel 6 are used to connect the first chamber 3 with the outside. The oil drain channel refers to a channel that connects the first chamber 3 with the outside so that when the first chamber 3 is compressed or the hydraulic pressure in the first chamber 3 increases, the oil in the first chamber 3 can be discharged. The oil return channel 14 is used to connect the first chamber 3 with the oil inlet 12 to form a bypass oil circuit relative to the one-way valve 13. The function of the oil return channel 14 is also to discharge the oil in the first chamber 3 when the first chamber 3 is compressed or the hydraulic pressure in the first chamber 3 increases, but it is not directly discharged to the outside of the tensioner 7, but returns to the oil inlet 12.

[0056] That is to say, the engine oil discharged from the first chamber 3 can be discharged to the oil pan through the oil drain passage, or flow back to the oil inlet 12 through the oil return passage 14 to achieve internal circulation.

[0057] Specifically, the oil return channel 14 always connects the first chamber 3 with the oil inlet 12, and the first oil drain channel 31 always connects the first chamber 3 with the outside. However, the second oil drain channel 6 has a connecting position and a disconnecting position. When the distance moved by the second cylinder 4 in the direction of compressing the second elastic member 41 is greater than or equal to the set threshold, the second oil drain channel 6 will switch to the disconnecting position. When the distance moved by the second cylinder 4 in the direction of compressing the second elastic member 41 is less than the set threshold, the second oil drain channel 6 switches to the connecting position. Among them, the threshold setting can be set by those skilled in the art according to the rigidity change value of the tensioner and the dynamic performance of the chain system.

[0058] In the above example, please continue to combine Figure 2 and Figure 3As shown, the first oil leakage channel 31 can generally be formed by the gap between the outer wall of the first cylinder 2 and the inner wall of the shell 1, or a separate slot can be opened on the outer wall of the first cylinder 2 to achieve a stable throttling effect. No matter which structure is used, it should be ensured that one end of the first oil leakage channel 31 is always connected to the first chamber 3, and the other end of the first oil leakage channel 31 leads to the outside of the tensioner 7. The return oil channel 14 is generally opened on the outer wall and bottom surface of the one-way valve 13, and cooperates with the shell 1 to form a slot connecting the first chamber 3 and the oil inlet 12. The slot is usually labyrinth-shaped to increase the throttling effect. Therefore, both the first oil leakage channel 31 and the return oil channel 14 can realize the basic function of draining the oil in the first chamber 3. The difference is that the oil consumption of the tensioner 7 can be reduced by bypassing the oil leakage through the return oil channel 14. Therefore, those skilled in the art can choose whether to set the first oil leakage channel 31 and the return oil channel 14 at the same time, and set their throttling parameters according to the rigidity change value of the tensioner and the dynamic performance of the chain system.

[0059] During the operation of the chain system of the engine, as the dynamic tension of the chain 9 changes, the tension rail 8 will swing to a certain extent, and the tension of the chain 9 acts on the second elastic member 41 through the second cylinder 4. At this time, the second elastic member 41 transmits the force of the chain 5 to the first cylinder 2 so that the first cylinder 2 forms a movement trend in the same direction as the second cylinder 4.

[0060] However, since the first cylinder 2 is subjected to the combined thrust of the hydraulic pressure in the first chamber 3 and the first elastic member 23, the first cylinder 2 will react to the second elastic member 41 through the first cylinder 2. At this time, the second elastic member 41 will be compressed, so that the second cylinder 4 will be displaced axially relative to the first cylinder 2 in the direction of the compression of the second elastic member 41. When the displacement meets the set threshold, the second cylinder 4 can close the second oil drain channel 6, and the engine oil can only be leaked from the remaining return oil channel 14 and the first oil drain channel 31 in the normally open state. This is equivalent to a reduction in the oil drain speed of the first chamber 3. At this time, the engine oil in the first chamber 3 has a large damping effect on the tension of the chain 9, and the tensioner 7 works in a high damping mode. Therefore, when the engine is working at high speed and high load, even if the tension and change of the chain 9 are large, the tensioner 7 can effectively tighten the chain 9. At this time, the tensioner 7 has a large stiffness and can keep the chain system running stably.

[0061] When the engine is operating at medium and low speeds, the chain 9 works stably, the tension is low and does not change much, and the swing amplitude of the tensioning rail 8 is small. Therefore, the displacement of the second cylinder 4 at this time is small and does not reach the set threshold. The second oil drain channel 6 is in a connected state, and the high-pressure engine oil in the first chamber 3 can be discharged faster through the return oil channel 14, the first oil drain channel 31 and the second oil drain channel 6 at the same time. In this way, the damping of the engine oil in the first chamber 3 on the tension of the chain 9 is effectively reduced, and the tensioner 7 works in a low damping mode. At this time, the tensioner 7 has a small stiffness, that is, the tensioner 7 is relatively soft, which can significantly reduce the dynamic tension of the chain 9 at this time, thereby reducing the friction loss of the chain system, reducing the noise of the chain system, and improving its reliability.

[0062] The specific structure of the second oil drain passage 6 is described below.

[0063] Embodiment 1

[0064] In a specific embodiment, Figure 3 As shown, the second oil leakage channel 6 includes a first section 61. The first section 61 is used to connect the first cavity 3 with the outside. The first section 61 penetrates the portion of the first cylinder 2 that encloses the first cavity 3 in the thickness direction, so as to form a first opening 61a and a second opening 61b on the cavity wall of the first cavity 3 and the outer peripheral wall of the first cylinder 2, respectively. The second opening 61b is connected to the outside of the tensioner 7, and the second cylinder 4 can block the second opening 61b or open the second opening 61b when moving axially, so as to switch the second oil leakage channel 6 between the disconnection position and the connection position.

[0065] The second end 22 of the first cylinder 2 forms a gap 11 with the housing 1 in the radial direction. The gap 11 is communicated with the outside, and the second opening 61b is located at the portion of the first cylinder 2 that encloses the gap 11. The second cylinder 4 is sleeved on the outside of the second end 22 and the flange 24, and the second cylinder 4 moves axially in the gap 11 to open or block the second opening 61b.

[0066] For more details, please see Figure 3 The first cylinder 2 is in a stepped diameter-changing structure in the axial direction, and the radial dimension of the first end 21 is larger than the radial dimension of the second end 22. The inner diameter of the shell 1 is adapted to the radial dimension of the first end 21, so that the radial dimension of the second end 22 is smaller than the inner diameter of the shell 1. Thus, a gap 11 connected to the outside is formed between the outer wall of the second end 22 and the inner wall of the shell 1. The second cylinder 4 can move in the axial direction of the first cylinder 2 in the gap 11.

[0067] In this embodiment, the second cylinder 4 compresses the second elastic member 41 under the push of the tensioning rail 8. The second elastic member 41 transmits the thrust applied by the tensioning rail 8 to the second cylinder 4 to the first cylinder 2, and the first cylinder 2 further compresses the first chamber 3 and the first elastic member 23. The hydraulic pressure of the first chamber 3 and the elastic force of the first elastic member 23 act together on the second elastic member 41, so that the second elastic member 41 undergoes a certain deformation, and the second cylinder 4 moves a certain distance in a manner to compress the second elastic member 41.

[0068] If the swing amplitude of the tensioning rail 8 is small, such as Figure 3 and Figure 4 As shown in the state, although the second cylinder 4 moves in the direction of compressing the second elastic member 41, the moving distance is less than the set threshold value, and the second cylinder 4 does not cover the second opening 61b. At this time, the second oil leakage channel 6, the first oil leakage channel 31 and the return oil channel 14 can all drain the oil in the first chamber 3, and the oil leakage speed of the first chamber 3 is faster. At this time, the stiffness of the tensioner 7 is relatively soft.

[0069] If the swing amplitude of the tensioning rail 8 is large, such as Figure 5 and Figure 6 As shown, when the distance moved by the second cylinder 4 reaches the set threshold, the inner wall of the second cylinder 4 will move to exceed the second opening 61b to cover and block the second opening 61b. At this time, the oil in the first chamber 3 cannot be leaked from the second oil drain channel 6, and only the first oil drain channel 31 and the oil return channel 14 are leaking oil. At this time, the oil leakage speed in the first chamber 3 is reduced, and the rigidity of the tensioner 7 is relatively hard.

[0070] Alternatively, if Figures 3 to 6 As shown, the second oil drain channel 6 also includes a second section 63 that plays a throttling role. Specifically, a filling portion 5 is also provided in the first chamber 3. The filling portion 5 is used to adjust the volume of the first chamber 3. The filling portion 5 is connected to the second end 22 of the first cylinder 2, and the side wall of the filling portion 5 and the inner wall of the second end 22 of the first cylinder 2 form the second section 63. The second section 63 is a third oil groove 51 in a spiral or other labyrinth shape opened in the filling portion, and the inner wall of the first cylinder 2 covers the third oil groove 51, thereby forming a channel for oil to flow.

[0071] One end of the second section 63 is communicated with the first chamber 3 , and the other end is communicated with the first port 61 a of the first section 61 , so that the oil in the first chamber 3 can enter the first section 61 from the second section 63 .

[0072] Embodiment 2

[0073] In this embodiment, if Figure 7 and Figure 8As shown, on the basis of the first embodiment, the outer wall surface of the second end 22 of the first cylinder 2 of the tensioner 7 is provided with an annular second oil groove 64 corresponding to the second mouth 61b, and the inner wall of the second cylinder 4 of the tensioner 7 is provided with a first oil groove 62 that is always connected with the second oil groove 64 and the second mouth 61b. The first section 61 penetrates the cylinder wall of the first cylinder 2 in the thickness direction. One end of the first section 61 is connected with the first cavity 3, and the other end can be connected with the first oil groove 62. The first oil groove 62 is provided in the portion of the second cylinder 4 that overlaps with the first cylinder 2.

[0074] When the second cylinder 4 moves relative to the first cylinder 2 , the first oil groove 62 can be switched between an open position and a closed position, so as to switch the second oil drain channel 6 between a connecting position and a disconnecting position.

[0075] Specifically, when the second oil drain channel 6 is in the disconnection position, the outer wall of the first cylinder 2 seals the first oil groove 62. On the contrary, in the connection position, the first oil groove 62 is connected with the second chamber 42.

[0076] The first cylinder 2 includes an open first end 21 and a closed second end 22, and the second cylinder 4 is sleeved on the second end 22 to form a second cavity 42 with the second end 22. The first cavity 3 is separated from the second cavity 42 by the end surface of the second end 22 of the first cylinder 2.

[0077] The first section 61 , the second oil groove 64 and the first oil groove 62 connect the first chamber 3 with the second chamber 42 .

[0078] The second chamber 42 is communicated with the outside through the oil outlet 43 .

[0079] In this embodiment, different from the first embodiment, the engine oil does not enter the gap 11 through the second opening 61 b, but enters the second oil groove 64 and the first oil groove 62 through the second opening 61 b.

[0080] Specifically, an annular groove corresponding to the second mouth 61b is provided on the outer wall surface of the second end 22 of the first cylinder 2. In the radial direction, the inner wall of the second cylinder 4 covers the notch of the groove, thereby forming an annular oil passage, namely the second oil groove 64. The second oil groove 64 plays a guiding role, so that the oil flowing out of the second mouth 61b can reach any position on the circumference. The inner wall of the second cylinder 4 is constructed with a first oil groove 62 along the axial direction. The first oil groove 62 is formed by the inner wall of the second cylinder 4 being recessed outward. In the radial direction, the outer wall of the first cylinder 2 covers the notch of the oil groove, thereby forming an oil passage. The first oil groove 62 plays a guiding role, so that the oil can flow along the extension direction of the oil groove.

[0081] See also Figure 7, when the first oil groove 62 is in the above-mentioned open position, in the axial direction, at least a part of the first oil groove 62 located in the second cavity 42 is staggered with the first cylinder 2 to form an oil drain port 62a. In other words, when the second cylinder 4 moves slightly in the axial direction relative to the first cylinder 2, the first oil groove 62 and the first cylinder 2 also move slightly relative to each other in the axial direction. At this time, the end of the first oil groove 62 in the extension direction is still not covered by the outer wall of the first cylinder 2. The engine oil in the first cavity can be drained into the second cavity 42 through the first section 61, the second oil groove 64 and the first oil groove 62 through the oil drain port 62a. By allowing the engine oil to enter the second cavity 42, the first cylinder 2 can be lubricated. At the same time, the oil drain speed of the first cavity 3 is also accelerated by the second oil drain channel 6 being connected to the second cavity 42. At this time, the hardness of the tensioner 7 is relatively low.

[0082] like Figure 8 As shown, when the first oil groove 62 is in the closed position, the oil groove is completely covered by the first cylinder 2 in the axial direction. At this time, the distance moved by the second cylinder 4 under the action of the tensioning rail 8 meets or exceeds the set threshold. At this time, the first oil groove 62 will also undergo corresponding axial movement relative to the first cylinder 2. The end of the extension of the first oil groove 62 (the position shown by the arrow A in the figure) moves relative to the first cylinder 2, so that the end of the extension of the first oil groove 62 is also covered by the outer wall of the first cylinder 2. At this time, the first oil groove 62 is blocked. After the engine oil enters the first oil groove 62 from the second mouth 61b, it cannot be discharged, so that the second oil drain channel 6 is in the disconnected position. As a result, the oil drain speed of the first chamber 3 is reduced, and the hardness of the tensioner 7 increases.

[0083] Optionally, the first oil groove 62 extends in a straight line in the axial direction. Of course, the first oil groove 62 can also extend in a spiral shape. Those skilled in the art can make their own choices as needed.

[0084] Optionally, in this embodiment, the second cylinder 4 is provided with an oil outlet 43 , and the oil outlet 43 is used to discharge the oil in the second chamber 42 .

[0085] The second cylinder 4 abuts against the tensioning rail 8 to compress the chain 9, and the oil outlet 43 is arranged at the position where the second cylinder 4 contacts the tensioning rail 8. Thus, the oil in the second chamber 42 can be discharged through the oil outlet 43 to lubricate the position where the second cylinder 4 contacts the tensioning rail 8.

[0086] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A hydraulic automatic tensioner, characterized in that: It comprises a shell, a first cylinder, a second cylinder, a first oil drain channel and a second oil drain channel, wherein the shell is sleeved on the first cylinder and forms a first cavity with the first cylinder, and the first cavity is used to contain the oil from the engine; The second cylinder is used to compress the chain. The second cylinder is sleeved on the first cylinder. The second cylinder can move axially relative to the first cylinder under the action of the chain. The first oil leakage channel and the second oil leakage channel are used to connect the first chamber with the outside, the first oil leakage channel is always connected with the outside, and the second oil leakage channel has a connecting position and a disconnecting position; The second oil leakage passage comprises a first section, the first section penetrates through the cylinder wall of the first cylinder to form a first opening in the first cavity, and a second opening is formed on the outer peripheral wall of the first cylinder; When the second cylinder moves axially, it can block the second opening or open the second opening to switch the second oil leakage channel between the connecting position and the disconnecting position.

2. The hydraulic automatic tensioner according to claim 1, characterized in that: The first cylinder is provided with a first end and a second end opposite to each other in the axial direction, and the second cylinder is sleeved on the second end.

3. The hydraulic automatic tensioner according to claim 2, characterized in that: The inner wall of the second cylinder is attached to the second opening to block the second opening, or is separated from the second opening to open the second opening.

4. The hydraulic automatic tensioner according to claim 2, characterized in that: The first end is built into the housing, the second end forms a gap with the housing in a radial direction, the gap is communicated with the outside, and the second opening is located at the portion of the first cylinder that encloses the gap; The second cylinder moves axially in the gap to open or block the second opening.

5. The hydraulic automatic tensioner according to claim 4, characterized in that: The first end is open, the second end is closed, the second cylinder and the second end form a second cavity, and the first cavity is spaced from the second cavity; The inner wall of the second cylinder is provided with a first oil groove which is always connected with the second opening, and the first cylinder is also provided with a second oil groove which is arranged on the side where the second opening is located, and the first oil groove and the second oil groove are always connected; At the disconnection station, the outer wall of the first cylinder seals the first oil groove; At the connecting station, the first oil groove is connected to the second cavity.

6. The hydraulic automatic tensioner according to claim 5, characterized in that: The second cylinder is provided with an oil outlet, and the oil outlet is used to discharge the oil and air in the second cavity; The second cylinder is used to abut against the tensioning rail to compress the chain, and the oil outlet is arranged at the position where the second cylinder contacts the tensioning rail.

7. The hydraulic automatic tensioner according to any one of claims 1 to 6, characterized in that: The housing is configured with an oil inlet, and the tensioner further comprises a one-way valve disposed at the oil inlet, wherein a valve port of the one-way valve is communicated with the oil inlet; The hydraulic automatic tensioner also includes an oil return channel. A groove is provided in the contact area between the outside of the one-way valve and the housing to form a bypass connection between the first chamber and the oil inlet to serve as the oil return channel.

8. The hydraulic automatic tensioner according to any one of claims 1 to 6, characterized in that: It also includes a filling part, which is disposed in the first cavity and connected to one end of the first cylinder close to the second cylinder; The second oil leakage channel further includes a second section, which is a third oil groove opened in the filling portion, one end of the third oil groove is communicated with the first cavity, and the other end of the third oil groove is communicated with the first port.

9. The hydraulic automatic tensioner according to claim 8, characterized in that: The third oil groove extends in a spiral shape.

10. An engine system, characterized in that: It comprises a chain and the hydraulic automatic tensioner according to any one of claims 1 to 9, wherein the hydraulic automatic tensioner presses the chain.

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