Tensioner, engine timing system, engine and vehicle

Abstract

The invention discloses a tensioner, an engine timing system, an engine and a vehicle, and the tensioner comprises a shell, an oil inlet, an oil outlet and an oil outlet, the shell is provided with a piston cavity with an opening, and the oil inlet is communicated with the piston cavity; the piston column is arranged in the piston cavity and can move relative to the shell, and the piston column is provided with an oil cavity communicated with the oil inlet, a first pressure relief channel communicated with the oil cavity and a second pressure relief channel communicated with the oil cavity; and the bypass valve is arranged at the second pressure relief channel, and the bypass valve is opened when the oil pressure in the oil cavity is higher than or equal to a preset value. The requirement that oil in the oil cavity obtains high damping when the engine is in the first rotating speed interval working condition can be met, and the problem that damping of the oil in the oil cavity is excessive when the engine is in the second rotating speed interval working condition can also be solved.

Description

Technical Field

[0001] This application relates to the field of engine technology, and in particular to a tensioner, an engine timing system, an engine, and a vehicle. Background Technology

[0002] In the engine timing system, the tensioner, as a transmission protection component, can suppress chain vibration, compensate for chain wear and elongation, and ensure precise synchronization between the crankshaft and camshaft. This directly affects the engine's power output efficiency, NVH (noise, vibration, and harshness) performance, and durability.

[0003] In related technologies, the tensioner adopts a damping adjustment design with a single pressure relief hole, that is, oil flow resistance is controlled only through a pressure relief hole with a fixed diameter. The pressure relief hole with a single fixed diameter has the following problems: To meet the higher damping requirements of the engine in the low-speed range of 800–3000 rpm, if the diameter of a single pressure relief hole is set too small, although the oil flow resistance can be increased through the narrow channel to form sufficient damping to suppress chain jumping and reduce the reciprocating micro-movement of the tensioner, barely meeting the low-speed stability requirements, when the engine speed increases to the medium-high speed range above 3500 rpm, the fixed small diameter pressure relief hole will cause the oil flow resistance to fail to adapt to the engine speed and reduce excessive damping effect. If the diameter of a single pressure relief hole is set too large, allowing the oil to flow quickly and reducing resistance, it can prevent excessive damping at engine speeds in the medium to high speed range. However, it will lead to a more prominent problem at low engine speeds: at low engine speeds, because the oil pressure is already low, the large-diameter pressure relief hole cannot form sufficient flow resistance, resulting in severely insufficient damping output. At this time, the lateral sway and linear velocity pulsation of the slack side of the chain cannot be effectively suppressed, the chain jumps more, and the reciprocating micro-movement amplitude of the tensioner piston column increases significantly. This forces the tensioner to frequently and rapidly extend and retract in response to vibration, directly causing an increase in frictional work and a significant increase in chain knocking noise, which seriously deteriorates NVH performance. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a tensioner that can improve upon the conventional solution's inability to simultaneously address the problems of low oil damping in the oil chamber when the engine is operating at low speeds and excessive oil damping in the oil chamber when the engine is operating at medium to high speeds.

[0005] This application also proposes an engine timing system, an engine, and a vehicle having the aforementioned tensioner.

[0006] A tensioner according to a first aspect of this application includes: a housing having an open piston chamber and an oil inlet communicating with the piston chamber; a piston rod disposed in the piston chamber and movable relative to the housing, the piston rod having an oil chamber communicating with the oil inlet, a first pressure relief channel communicating with the oil chamber, and a second pressure relief channel communicating with the oil chamber; and a bypass valve disposed at the second pressure relief channel, the bypass valve being opened when the oil pressure in the oil chamber is higher than or equal to a preset value.

[0007] The tensioner according to the embodiments of this application has at least the following beneficial effects: When the tensioner of this application is applied to the engine timing system, when the engine is operating in the first speed range, the oil pressure in the oil chamber is lower than the opening pressure of the bypass valve, the bypass valve remains closed, and the oil in the oil chamber is discharged through the first pressure relief channel. The orifice diameter of the first pressure relief channel can be set to meet the requirement that the oil in the oil chamber forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod in response to chain tension changes, forcing it to respond smoothly to chain vibration displacement. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain, reducing frictional work; on the other hand, the high damping characteristics make the piston rod's response to chain vibration smoother, reducing chain noise and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), if the oil pressure in the oil chamber is higher than or equal to a preset value, the bypass valve opens. The oil in the oil chamber is discharged not only through the first pressure relief channel but also through the second pressure relief channel. This effectively increases the oil discharge flow rate, reduces the oil flow resistance in the oil chamber, and automatically weakens the damping effect. This allows the piston rod to adjust its displacement more flexibly according to changes in chain tension, improving the energy loss problem caused by excessive damping when the engine is operating in the second speed range. Simultaneously, it reduces the risk of chain vibration, allowing the piston rod to quickly adapt to chain tension fluctuations and improving the problem of an overly tight or loose chain. Thus, by setting up a first pressure relief channel and a second pressure relief channel, and by using a bypass valve to control the opening or blocking of the second pressure relief channel, this application can meet the requirement of higher damping for the oil in the oil chamber when the engine is operating in the first speed range, and also improve the problem of excessive damping in the oil chamber when the engine is operating in the second speed range.

[0008] According to some embodiments of this application, the preset value is greater than or equal to 300 kPa and less than or equal to 450 kPa; and / or, the axis of the first pressure relief channel is parallel to the direction of movement of the piston rod; and / or, the axis of the second pressure relief channel is parallel to the direction of movement of the piston rod.

[0009] According to some embodiments of this application, the first pressure relief channel includes a first pressure relief hole, which extends through the cavity wall of the oil chamber, and the diameter of the first pressure relief hole is D1, satisfying: 0.20mm≤D1≤0.25mm.

[0010] According to some embodiments of this application, the second pressure relief channel includes a second pressure relief hole, the second pressure relief hole having an oil inlet end and an oil outlet end disposed opposite to each other, the oil inlet end penetrating to the cavity wall of the oil chamber; The bypass valve includes a valve core disposed on the piston rod and a first elastic element disposed on the piston rod and acting on the valve core; Specifically, when the oil pressure in the oil chamber is lower than the preset value, under the elastic action applied by the first elastic element, the valve core abuts against the piston column to close the oil outlet end; when the oil pressure in the oil chamber is higher than or equal to the preset value, the valve core moves relative to the piston column to open the oil outlet end.

[0011] According to some embodiments of this application, the diameter of the second pressure relief hole is D2, which satisfies: 0.45mm≤D2≤0.60mm.

[0012] According to some embodiments of this application, the second pressure relief channel further includes a third pressure relief hole disposed in the housing and located at the end of the second pressure relief hole away from the oil cavity, the first elastic member is disposed in the third pressure relief hole and abuts against the end of the valve core away from the oil cavity, a support member is disposed on the housing, the support member is used to support the end of the first elastic member away from the valve core, and the second pressure relief channel further includes a fourth pressure relief hole opened in the support member and communicating with the third pressure relief hole.

[0013] According to some embodiments of this application, the tensioner further includes a second elastic element and a damping pad; The direction of motion of the piston rod when it extends is defined as the first direction, and the direction of motion when it compresses is defined as the second direction; The second elastic member includes a first abutting end and a second abutting end disposed opposite to each other, the first abutting end and the second abutting end being arranged along the first direction; The damping pad is disposed on the housing, the first abutting end abuts against the damping pad, and the second abutting end abuts against the piston rod; or, the damping pad is disposed on the piston rod, the first abutting end abuts against the housing, and the second abutting end abuts against the damping pad. The second elastic element is used to apply a force along the first direction to the piston rod.

[0014] According to some embodiments of this application, the tensioner further includes a second elastic element and a damping pad; The direction of motion of the piston rod when it extends is defined as the first direction, and the direction of motion when it compresses is defined as the second direction; The piston rod has a first end and a second end that are arranged opposite to each other, the first end and the second end are arranged along the first direction, and the oil cavity penetrates the end face of the first end and forms an opening; The sidewall of the piston chamber is formed with a positioning step surface, and the opening is oriented toward the positioning step surface; The second elastic member includes a first abutment end and a second abutment end disposed opposite to each other, the first abutment end and the second abutment end being arranged along the first direction, the damping pad being disposed on the positioning step surface, a portion of the structure of the second elastic member passing through the oil cavity and abutting the second abutment end against the piston rod, and a portion of the structure of the second elastic member extending out of the oil cavity and abutting the first abutment end against the damping pad.

[0015] According to some embodiments of this application, the thickness of the damping pad is greater than or equal to 0.3 mm and less than or equal to 1.0 mm, wherein the thickness direction of the damping pad is parallel to the first direction.

[0016] An engine timing system according to a second aspect of this application includes: a chain; a tensioning arm abutting against the chain; and a tensioner according to the above embodiment, wherein the piston rod abuts against the side of the tensioning arm away from the chain.

[0017] The engine timing system according to the embodiments of this application has at least the following beneficial effects: In the engine timing system of this application, when the engine is operating in the first speed range, the oil pressure in the oil chamber is lower than the opening pressure of the bypass valve, the bypass valve remains closed, and the oil in the oil chamber is discharged through the first pressure relief channel. The orifice diameter of the first pressure relief channel can be set to meet the requirement that the oil in the oil chamber forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod due to chain tension changes, forcing it to respond smoothly to chain vibration displacement. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain, reducing frictional work; on the other hand, the high damping characteristic makes the piston rod's response to chain vibration smoother, reducing chain noise and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), if the oil pressure in the oil chamber is higher than or equal to a preset value, the bypass valve opens. The oil in the oil chamber is discharged not only through the first pressure relief channel but also through the second pressure relief channel. This effectively increases the oil discharge flow rate, reduces the oil flow resistance in the oil chamber, and automatically weakens the damping effect. This allows the piston rod to adjust its displacement more flexibly according to changes in chain tension, improving the energy loss problem caused by excessive damping when the engine is operating in the second speed range. Simultaneously, it reduces the risk of chain vibration, allowing the piston rod to quickly adapt to chain tension fluctuations and improving the problem of an overly tight or loose chain. Thus, by setting up a first pressure relief channel and a second pressure relief channel, and by using a bypass valve to control the opening or blocking of the second pressure relief channel, this application can meet the requirement of higher damping for the oil in the oil chamber when the engine is operating in the first speed range, and also improve the problem of excessive damping in the oil chamber when the engine is operating in the second speed range.

[0018] An engine according to a third aspect of this application includes the engine timing system described above.

[0019] The engine according to the embodiments of this application has at least the following beneficial effects: In the engine of this application, when the engine is operating in the first speed range, the oil pressure in the oil chamber is lower than the opening pressure of the bypass valve, the bypass valve remains closed, and the oil in the oil chamber is discharged through the first pressure relief channel. The orifice diameter of the first pressure relief channel can be set to meet the requirement that the oil in the oil chamber forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod due to chain tension changes, forcing it to respond smoothly to chain vibration displacement. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain, reducing frictional work; on the other hand, the high damping characteristic makes the piston rod's response to chain vibration smoother, reducing chain noise and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), if the oil pressure in the oil chamber is higher than or equal to a preset value, the bypass valve opens. The oil in the oil chamber is discharged not only through the first pressure relief channel but also through the second pressure relief channel. This effectively increases the oil discharge flow rate, reduces the oil flow resistance in the oil chamber, and automatically weakens the damping effect. This allows the piston rod to adjust its displacement more flexibly according to changes in chain tension, improving the energy loss problem caused by excessive damping when the engine is operating in the second speed range. Simultaneously, it reduces the risk of chain vibration, allowing the piston rod to quickly adapt to chain tension fluctuations and improving the problem of an overly tight or loose chain. Thus, by setting up a first pressure relief channel and a second pressure relief channel, and by using a bypass valve to control the opening or blocking of the second pressure relief channel, this application can meet the requirement of higher damping for the oil in the oil chamber when the engine is operating in the first speed range, and also improve the problem of excessive damping in the oil chamber when the engine is operating in the second speed range.

[0020] The vehicle according to the fourth aspect of this application includes the engine described in the above embodiments.

[0021] The vehicle according to the embodiments of this application has at least the following beneficial effects: The vehicle described in this application is equipped with the aforementioned engine. When the engine is operating in the first speed range, the oil pressure in the oil chamber is lower than the opening pressure of the bypass valve, the bypass valve remains closed, and the oil in the oil chamber is discharged through the first pressure relief channel. The orifice diameter of the first pressure relief channel can be set to meet the requirement that the oil in the oil chamber forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod due to chain tension changes, forcing it to respond smoothly to chain vibration displacement. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain, reducing frictional work; on the other hand, the high damping characteristic makes the piston rod's response to chain vibration smoother, reducing chain noise and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), if the oil pressure in the oil chamber is higher than or equal to a preset value, the bypass valve opens. The oil in the oil chamber is discharged not only through the first pressure relief channel but also through the second pressure relief channel. This effectively increases the oil discharge flow rate, reduces the oil flow resistance in the oil chamber, and automatically weakens the damping effect. This allows the piston rod to adjust its displacement more flexibly according to changes in chain tension, improving the energy loss problem caused by excessive damping when the engine is operating in the second speed range. Simultaneously, it reduces the risk of chain vibration, allowing the piston rod to quickly adapt to chain tension fluctuations and improving the problem of an overly tight or loose chain. Thus, by setting up a first pressure relief channel and a second pressure relief channel, and by using a bypass valve to control the opening or blocking of the second pressure relief channel, this application can meet the requirement of higher damping for the oil in the oil chamber when the engine is operating in the first speed range, and also improve the problem of excessive damping in the oil chamber when the engine is operating in the second speed range.

[0022] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0023] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a partial structural diagram of an engine timing system according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a tensioner according to one embodiment of this application; Figure 3 This is a cross-sectional view of a tensioner according to an embodiment of this application; Figure 4 for Figure 3 Enlarged view of point A in the middle; Figure 5 for Figure 3 Enlarged view of point B in the middle; Figure 6This is a schematic diagram of the tension arm structure according to one embodiment of this application. Figure 1 ; Figure 7 This is a schematic diagram of the tension arm structure according to one embodiment of this application. Figure 2 ; Figure 8 A cross-sectional view of a tension arm according to an embodiment of this application. Figure 1 ; Figure 9 A cross-sectional view of a tension arm according to an embodiment of this application. Figure 2 ; Figure 10 It is a cross-section of the tension arm in the traditional scheme. Figure 1 ; Figure 11 It is a cross-section of the tension arm in the traditional scheme. Figure 2 ; Figure 12 This is a cross-section of the guide rail in a traditional design. Figure 1 ; Figure 13 This is a cross-section of the guide rail in a traditional design. Figure 2 ; Figure 14 This is a schematic diagram of the structure of a guide rail according to one embodiment of this application; Figure 15 A cross-sectional view of a guide rail according to one embodiment of this application. Figure 1 ; Figure 16 A cross-sectional view of a guide rail according to one embodiment of this application. Figure 2 ; Figure 17 for Figure 14 Enlarged view of point C in the middle; Figure 18 for Figure 14 Enlarged view of point D in the middle.

[0024] Icon labels: 100. Tensioner; 110. Housing; 111. Piston chamber; 1111. Opening; 112. Oil inlet; 113. Positioning step surface; 120. Piston column; 120a. First end; 120b. Second end; 121. Oil chamber; 1211. Opening; 122. First pressure relief channel; 1221. First pressure relief hole; 123. Second pressure relief channel; 1231. Second pressure relief hole; 1232. Third pressure relief hole; 125. Limiting step surface; 130. Bypass valve; 131. Valve core; 132. First elastic element; 133. Support element; 1331. Fourth pressure relief hole; 140. Second elastic element; 141. First supporting end; 142. Second supporting end; 150. Damping pad; 200. Tensioning arm; 201. First side portion; 202. Second side portion; 203. Connecting portion; 210. Tensioning surface; 211. Inlet section; 212. Main contact section; 213. Outlet section; 214. First transition section; 215. Second transition section; 210a. First end point; 210b. Second end point; 210c. First protrusion; 220. First reinforcing rib; 300. Sprockets; 400. Chain; 410. Roller; 500, guide rail; 501, third side; 502, fourth side; 510, guide surface; 510a, inlet end; 510b, outlet end; 511, third end point; 512, fourth end point; 513, second protrusion; 520, guide arc surface; 530, exit arc surface; 540, second reinforcing rib; 600, First wedge-shaped gap; 700, Second wedge gap. Detailed Implementation

[0025] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0026] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application 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 application. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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 between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] like Figure 1 As shown, the engine timing system provided in one embodiment of this application can be applied to vehicles, wherein the vehicle can be a private car, such as a sedan, SUV, MPV or pickup truck; the vehicle can also be a commercial vehicle, such as a van or bus; the vehicle can be a gasoline vehicle or a range-extended electric vehicle.

[0029] The engine timing system includes a tensioner 100, a tensioning arm 200, a sprocket 300, a chain 400, and a guide rail 500. The chain 400 is fitted over the sprocket 300. The tensioning arm 200 abuts against the chain 400, specifically against the slack side of the chain 400. The tensioner 100 provides force to the tensioning arm 200, which then transmits the force to the slack side of the chain 400, thereby tensioning the chain 400 and reducing the risk of it becoming loose. The guide rail 500 abuts against the chain 400, specifically against the tight side of the chain 400, and guides the chain 400.

[0030] Combination Figure 2 , Figure 3 and Figure 4 The tensioner 100 includes a housing 110, a piston rod 120, and a bypass valve 130.

[0031] like Figure 3 As shown, the housing 110 is provided with a piston chamber 111 having an opening 1111 and an oil inlet 112 communicating with the piston chamber 111.

[0032] Specifically, the housing 110 is a hollow structure with a piston chamber 111. One end of the piston chamber 111 has an opening 1111. The housing 110 also has an oil inlet 112 communicating with the piston chamber 111. Specifically, the oil inlet 112 is located on the side wall of the piston chamber 111 at the end away from the opening 1111. The oil inlet 112 is used to communicate with the engine's oil passage. When the engine is running, oil enters the piston chamber 111 through the oil inlet 112.

[0033] The piston rod 120 is disposed in the piston chamber 111 and can move relative to the housing 110. The piston rod 120 is provided with an oil chamber 121 communicating with the oil inlet 112. It should be noted that the direction of movement of the piston rod 120 when it extends is defined as the first direction, and the direction of movement when it is compressed is defined as the second direction.

[0034] It is understood that the piston rod 120 is a hollow structure with an oil chamber 121, and the oil chamber 121 is connected to the oil inlet 112. When oil enters the oil chamber 121 through the oil inlet 112, it flows into the oil chamber 121. Under the action of oil pressure, the piston rod 120 will move relative to the housing 110 in the first direction. Figure 1 and Figure 3 It should be noted that in the engine timing system, the tensioner 100 is located on the side of the tensioning arm 200 away from the chain 400, and the piston rod 120 is held against the side of the tensioning arm 200 away from the chain 400. The first direction is also the direction of the tensioner 100 toward the tensioning arm 200. The piston rod 120 can extend and retract simultaneously due to the oil pressure change in the oil chamber 121 and the tension change of the chain 400.

[0035] like Figure 3 As shown, specifically, the piston rod 120 has a first end 120a and a second end 120b arranged opposite to each other. The first end 120a and the second end 120b of the piston rod 120 are arranged along a first direction. The oil chamber 121 is located inside the piston rod 120 and penetrates the end face of the first end 120a of the piston rod 120. The oil inlet 112 is located in the housing 110 and is located on the side of the first end 120a of the piston rod 120 away from the second end 120b. When oil enters the oil chamber 121 through the oil inlet 112, it will flow into the oil chamber 121. Under the action of oil pressure, the piston rod 120 will move relative to the housing 110 along the first direction.

[0036] Combination Figure 3 and Figure 4 Furthermore, the piston rod 120 is also provided with a first pressure relief channel 122 communicating with the oil chamber 121 and a second pressure relief channel 123 communicating with the oil chamber 121. The bypass valve 130 is provided at the second pressure relief channel 123. The bypass valve 130 is opened when the oil pressure in the oil chamber 121 is higher than or equal to a preset value.

[0037] Specifically, the first pressure relief channel 122 and the second pressure relief channel 123 are located at the second end 120b of the piston rod 120 and are both connected to the oil chamber 121. The first pressure relief channel 122 is normally open, and the second pressure relief channel 123 is opened or blocked under the control of the bypass valve 130. Specifically, when the oil pressure in the oil chamber 121 is lower than a preset value, the bypass valve 130 is closed and the second pressure relief channel 123 is blocked by the bypass valve 130. When the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the bypass valve 130 is opened, thereby making the second pressure relief channel 123 open.

[0038] In the engine timing system of this application, when the engine is operating in the first speed range, the oil pressure in the oil chamber 121 is lower than the opening pressure of the bypass valve 130, the bypass valve 130 remains closed, and the oil in the oil chamber 121 is discharged through the first pressure relief channel 122. The orifice diameter of the first pressure relief channel 122 can be set to meet the requirement that the oil in the oil chamber 121 forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod 120 due to tension changes in the chain 400, forcing it to respond smoothly to the vibration displacement of the chain 400. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain 400, reducing frictional work; on the other hand, the high damping characteristic makes the piston rod 120 respond more smoothly to the vibration of the chain 400, reducing the noise of the chain 400 and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), when the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the bypass valve 130 opens. The oil in the oil chamber 121 is discharged not only through the first pressure relief channel 122, but also through the second pressure relief channel 123. At this time, it is equivalent to increasing the discharge flow rate of the oil. The flow resistance of the oil in the oil chamber 121 is reduced, and the damping effect is automatically weakened. This allows the piston rod 120 to adjust its displacement more flexibly with the tension change of the chain 400, which improves the problem of energy loss caused by excessive damping when the engine is operating in the second speed range. At the same time, it can reduce the vibration risk of the chain 400 and allow the piston rod 120 to quickly adapt to the tension fluctuation of the chain 400, improving the problem of the chain 400 being too tight or too loose. Thus, by setting a first pressure relief channel 122 and a second pressure relief channel 123, and by setting a bypass valve 130 to control the opening or blocking of the second pressure relief channel 123, this application can meet the requirement that the oil in the oil chamber 121 obtains higher damping when the engine is in the first speed range, and can also meet the problem of excessive damping of the oil in the oil chamber 121 when the engine is in the second speed range.

[0039] It should be noted that the engine operating in the first speed range can be defined as an engine speed between 800 rpm and 3000 rpm, while the engine operating in the second speed range can be defined as an engine speed greater than 3500 rpm. When the engine is operating in the first speed range, the oil pressure is <250 kPa. When the engine is operating in the second speed range, the oil pressure is typically ≥300 kPa–450 kPa, where the aforementioned preset values ​​are greater than or equal to 300 kPa and less than or equal to 450 kPa.

[0040] In some embodiments, the axis of the first pressure relief channel 122 is parallel to the direction of movement of the piston rod 120. It is understood that since the axis of the first pressure relief channel 122 is parallel to the direction of movement of the piston rod 120, the flow direction of the oil within the first pressure relief channel 122 is consistent with the axial movement direction of the piston rod 120. The oil in the oil chamber 121 can enter the first pressure relief channel 122 without changing its flow direction, avoiding localized eddies or flow deviations caused by directional changes. Furthermore, the core resistance to the extension and retraction of the piston rod 120 is the oil damping force. The direction of the damping force must be opposite to and collinear with the direction of movement of the piston rod 120, thus effectively constraining the extension and retraction motion.

[0041] Furthermore, the axis of the second pressure relief channel 123 is parallel to the direction of movement of the piston rod 120. It can be understood that when the axis of the second pressure relief channel 123 is parallel to the direction of movement of the piston rod 120, and the second pressure relief channel 123 is open, the flow direction of the oil within the second pressure relief channel 123 is consistent with the axial movement direction of the piston rod 120. The oil in the oil chamber 121 can enter the second pressure relief channel 123 without changing its flow direction, avoiding local eddies or flow deviations caused by directional changes. In addition, the core of the resistance to the extension and retraction of the piston rod 120 is the oil damping force. The direction of the damping force must be opposite to and collinear with the direction of movement of the piston rod 120, thus effectively constraining the extension and retraction motion.

[0042] like Figure 4 As shown, further, the first pressure relief channel 122 includes a first pressure relief hole 1221, which extends through the cavity wall of the oil chamber 121. The diameter of the first pressure relief hole 1221 is D1, satisfying: 0.20mm ≤ D1 ≤ 0.25 mm. For example, the value of the diameter D1 of the first pressure relief hole 1221 can be, but is not limited to, 0.20mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, or 0.25mm.

[0043] It should be noted that when the engine is operating in the first speed range, the oil pressure is low (typically <250 kPa). By setting the orifice diameter D1 of the first pressure relief orifice 1221 within the range of 0.20 mm–0.25 mm, a stable throttling damping effect can be formed under low oil pressure. Specifically, if the orifice diameter D1 of the first pressure relief orifice 1221 is <0.20 mm, it will lead to poor oil flow, and excessive damping may easily cause the piston rod 120 to stick; if the orifice diameter D1 of the first pressure relief orifice 1221 is >0.25 mm, sufficient damping cannot be formed.

[0044] In some embodiments, the second pressure relief channel 123 includes a second pressure relief hole 1231, which has an oil inlet end and an oil outlet end disposed opposite to each other, with the oil inlet end penetrating to the cavity wall of the oil chamber 121; the bypass valve 130 includes a valve core 131 disposed on the piston rod 120, and a first elastic member 132 disposed on the piston rod 120 and acting on the valve core 131. When the oil pressure in the oil chamber 121 is lower than a preset value, under the elastic action applied by the first elastic member 132, the valve core 131 abuts against the piston rod 120 to close the oil outlet end of the second pressure relief hole 1231. When the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the valve core 131 moves relative to the piston rod 120 to open the oil outlet end of the second pressure relief hole 1231. The first elastic member 132 may be a spring or a sheet, and the valve core 131 may be spherical, hemispherical, square, etc.

[0045] It is understandable that the valve core 131 is located at the end of the second pressure relief hole 1231 away from the oil chamber 121, and the first elastic element 132 is used to apply a force to the valve core 131 in the first direction. When the oil pressure in the oil chamber 121 is lower than the preset value, the force exerted by the first elastic element 132 on the valve core 131 is greater than the force exerted by the oil in the oil chamber 121 on the first elastic element 132. The valve core 131 closes the oil outlet end of the second pressure relief hole 1231, and the second pressure relief channel 123 is blocked. When the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the force exerted by the first elastic element 132 on the valve core 131 is less than the force exerted by the oil in the oil chamber 121 on the first elastic element 132. The valve core 131 is pushed open by the oil in the oil chamber 121, so that the second pressure relief channel 123 is open. In addition, when the oil pressure in the oil chamber 121 drops below the preset value, the first elastic element 132 can drive the valve core 131 to reset and block the second pressure relief channel 123 again.

[0046] It should be noted that the second pressure relief hole 1231 is the core flow structure of the second pressure relief channel 123. When the bypass valve 130 is closed (engine speed is between 800 rpm and 3000 rpm, oil pressure < 250 kPa), the oil in the oil chamber 121 can enter the second pressure relief hole 1231, and the second pressure relief hole 1231 can be pre-filled with oil. When the bypass valve 130 is opened (engine speed > 3500 rpm, oil pressure ≥ 300 kPa to 450 kPa), the valve core 131 is instantly pushed open, and the oil pre-filled in the first pressure relief hole 1231 is discharged quickly without lag, avoiding the pressure relief response lag caused by air in the hole, and realizing the rapid decay of the damping effect.

[0047] Furthermore, the diameter of the second pressure relief hole 1231 is D2, satisfying: 0.45mm ≤ D2 ≤ 0.60 mm. For example, the value of the diameter D2 of the second pressure relief hole 1231 can be, but is not limited to, 0.45mm, 0.47mm, 0.49mm, 0.51mm, 0.53mm, 0.55mm, 0.57mm, or 0.60mm.

[0048] It is understandable that after the bypass valve 130 is opened, if the diameter of the second pressure relief hole 1231 is too small, even if the second pressure relief hole 1231 is filled with oil, the transient oil discharge speed will be insufficient due to excessive oil viscous resistance, resulting in a delayed pressure relief response. In this application, the diameter of the second pressure relief hole 1231 is not less than 0.45 mm, which allows the oil pre-filled in the second pressure relief hole 1231 to overcome viscous resistance and be discharged quickly, and the damping effect will decay rapidly. However, if the diameter of the second pressure relief hole 1231 is too large, the amount of oil leaking from the second pressure relief hole 1231 during the valve closing stage of the bypass valve 130 will increase, resulting in a decrease in oil damping in the oil chamber 121, affecting the adjustment effect on the chain 400. By setting the diameter D2 of the second pressure relief hole 1231 between 0.45 mm and 0.60 mm, the problems of the second pressure relief hole 1231 being too small or too large can be improved.

[0049] Furthermore, the second pressure relief channel 123 also includes a third pressure relief hole 1232 located on the housing 110 and at the end of the second pressure relief hole 1231 away from the oil chamber 121. The diameter of the third pressure relief hole 1232 is larger than the diameter of the second pressure relief hole 1231, and the third pressure relief hole 1232 is coaxially arranged with the second pressure relief hole 1231. A limiting step surface 125 is formed between the third pressure relief hole 1232 and the second pressure relief hole 1231. When the valve core 131 blocks the second pressure relief channel 123, the valve core 131 is supported on the limiting step surface 125 and forms a seal with the limiting step surface 125.

[0050] Furthermore, the first elastic element 132 is disposed within the third pressure relief hole 1232 and abuts against the end of the valve core 131 away from the oil chamber 121. Furthermore, a support element 133 is provided on the housing 110, which supports the end of the first elastic element 132 away from the valve core 131. It should be noted that the second pressure relief channel 123 also includes a fourth pressure relief hole 1331 disposed in the support element 133. The fourth pressure relief hole 1331 communicates with the third pressure relief hole 1232, allowing oil that has entered the third pressure relief hole 1232 through the second pressure relief hole 1231 to flow out.

[0051] In other embodiments, a support frame can be provided inside the oil cavity 121. The support frame has a similar function to the support member 133, which is used to provide support for the first elastic member 132. Specifically, one end of the first elastic member 132 is connected to the end of the valve core 131 near the oil cavity 121, and the other end is connected to the support frame. The first elastic member 132 is in a stretched state, which continuously provides the valve core 131 with a force along the second direction.

[0052] like Figure 3 As shown, the tensioner 100 also includes a second elastic element 140, which abuts between the housing 110 and the piston rod 120 and is used to apply a force to the piston rod 120 in a first direction.

[0053] Understandably, after the engine starts, regardless of the speed, the second elastic element 140 consistently applies a continuous thrust in the first direction to the piston rod 120. This force is transmitted to the slack side of the chain 400 by the piston rod 120 pushing against the tensioning arm 200, thus improving the slackness of the chain 400 caused by its own weight and vibration. Furthermore, during engine operation, the tension of the chain 400 dynamically fluctuates with changes in engine speed and load. The elastic deformation of the second elastic element 140 can quickly absorb these fluctuations, preventing sudden tension changes. Simultaneously, over long-term use, the chain 400 may experience slight elongation due to wear; the second elastic element 140 can compensate for this elongation, maintaining a stable tension.

[0054] Specifically, the second elastic member 140 includes a first abutting end 141 and a second abutting end 142 opposite to the first abutting end 141. The first abutting end 141 and the second abutting end 142 are arranged sequentially along a first direction. The first abutting end 141 of the second elastic member 140 abuts against the housing 110, and the second abutting end 142 abuts against the piston rod 120. The second elastic member 140 may be a spring or a sheet.

[0055] Combination Figure 3 and Figure 5 Furthermore, the piston chamber 111 has a positioning step surface 113, and the oil chamber 121 penetrates the end face of the first end 120a of the piston rod 120 and forms an opening 1211. The opening 1211 is disposed facing the positioning step surface 113. A portion of the structure of the second elastic member 140 passes through the oil chamber 121 and abuts the second abutting end 142 against the piston rod 120. A portion of the structure of the second elastic member 140 extends out of the oil chamber 121 and abuts the first abutting end 141 against the positioning step surface 113.

[0056] Understandably, the oil cavity 121 can serve as a guide hole for the second elastic element 140, allowing part of the structure of the second elastic element 140 to pass through the oil cavity 121. This reduces the risk of lateral displacement caused by the reciprocating motion of the piston rod 120, ensuring that the thrust of the second elastic element 140 is accurately transmitted to the piston rod 120 along the first direction, thereby stabilizing the loose side of the chain 400 and improving the problem of uneven tension caused by the easy displacement of the second elastic element 140.

[0057] Furthermore, the tensioner 100 also includes a damping pad 150, which is disposed on the housing 110 and abuts against the first abutting end 141 of the second elastic member 140. The damping pad 150 may be made of HNBR or FKM.

[0058] It should be noted that when the engine is operating in the first speed range, the piston rod 120 moves at a low speed, and the damping pad 150 is slowly compressed / released. The damping pad 150 can provide additional damping for the piston rod 120, thereby limiting the rapid expansion and contraction of the piston rod 120 due to the tension changes of the chain 400, and forcing it to respond smoothly to the vibration displacement of the chain 400. When the engine is operating in the second speed range, the oil pressure in the oil chamber 121 increases, causing the bypass valve 130 to open. The damping in the oil chamber 121 is dominated by the first pressure relief channel 122 and the second pressure relief channel 123. At this time, the piston rod 120 moves at a high speed. When the damping pad 150 is subjected to the rapid impact of the piston rod 120, it will be impacted again before it has time to rebound, and the damping it provides to the piston rod 120 is limited. In addition, the damping pad 150 can play a buffering role, absorbing impact energy through elastic deformation. At the same time, the damping pad 150 can prevent the first abutting end 141 of the second elastic member 140 from directly contacting the housing 110, improving the problem of rigid collision between the second elastic member 140 and the housing 110, improving the problem of damping abrupt change caused by rigid hard impact, and can also play a role in noise reduction.

[0059] Furthermore, the damping pad 150 is disposed on the positioning step surface 113. The positioning step surface 113 can provide an installation reference for the damping pad 150. The positioning step surface 113 has a flat installation surface, which can ensure the flatness of the damping pad 150 after installation and improve the uniformity of the force on the damping pad 150.

[0060] The damping pad 150 has a thickness greater than or equal to 0.3 mm and less than or equal to 1.0 mm, and the thickness direction of the damping pad 150 is parallel to the first direction. For example, the thickness of the damping pad 150 can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm.

[0061] It should be noted that the thickness of the damping pad 150, greater than or equal to 0.3 mm and less than or equal to 1.0 mm, ensures that the damping pad 150 fully performs its core functions of additional damping and noise reduction in the first engine speed range (800 rpm to 3000 rpm), while also controlling its deformation in the second speed range (>3500 rpm), avoiding additional damping interference with the rapid extension and retraction of the piston rod 120. Specifically, when the engine is operating in the first speed range, the piston rod 120 performs a small stroke and low-speed reciprocating extension and retraction of approximately 0 to 0.5 mm. The damping pad 150 within this thickness range can be fully compressed / released by the short stroke of the piston rod 120, generating stable additional damping, effectively limiting the rapid extension and retraction of the piston rod, forcing it to respond smoothly to chain vibration, further reducing chain slack side oscillation and friction work, and improving NVH performance. If the thickness of the damping pad 150 is less than 0.3 mm, it may not be able to provide adequate additional damping for the piston rod 120 when the engine is operating in the first speed range, and the energy absorption effect will be significantly reduced. If the thickness of the damping pad 150 is greater than 1.0 mm, it may significantly encroach on the effective oil storage space of the piston chamber 111, resulting in the effective oil storage volume being lower than the design value, which in turn leads to the failure of precise control of the oil damping.

[0062] It should be noted that the damping pad 150 is a detachable structural component. The oil storage volume of the piston chamber 111 can be adjusted by placing damping pads 150 of different thicknesses within the piston chamber 111. Understandably, increasing the thickness of the damping pad 150 reduces the oil storage volume of the piston chamber 111, while decreasing its thickness increases it. A smaller piston chamber 111 makes the oil pressure more sensitive to changes. Thus, by adjusting the thickness of the damping pad 150 to change the oil storage volume, it is possible to adapt to the damping requirements of engines of different displacements without modifying core structures such as the first pressure relief channel 122, the second pressure relief channel 123, and the bypass valve 130, simply by adjusting the dimensions of these components.

[0063] It should be noted that, in other embodiments, the damping pad 150 may be disposed on the housing 110 for abutting against the second end 120b of the second elastic member 140.

[0064] like Figure 6 As shown, the tensioning arm 200 has a first side portion 201 and a second side portion 202 disposed opposite to the first side portion 201.

[0065] Combination Figure 1 and Figure 6The tension arm 200 is used to contact the chain 400, thereby transmitting tension force to the chain 400 and guiding the chain 400. The first side 201 of the tension arm 200 is used to directly contact the chain 400, and the second side 202 of the tension arm 200 refers to the side of the tension arm 200 facing away from the chain 400.

[0066] Combination Figure 1 , Figure 6 and Figure 7 Furthermore, the first side portion 201 has a tensioning surface 210, the extension path of which is an arc shape protruding toward the chain 400, and the chain 400 can move along the extension direction of the tensioning surface 210.

[0067] It is understood that the tensioning surface 210 is the surface of the first side 201 facing away from the second side 202, and the chain 400 in contact with the tensioning surface 210 can run along the extension direction of the tensioning surface 210. It should be noted that the part of the chain 400 in contact with the tensioning surface 210 is one side of the chain 400 along its own thickness direction.

[0068] Combination Figure 6 and Figure 7 The tensioning surface 210 includes an inlet section 211, a main contact section 212, and an outlet section 213 arranged along the extension direction of the tensioning surface 210. When the chain 400 is running, the rollers 410 of the chain 400 contact the inlet section 211, the main contact section 212, and the outlet section 213 in sequence. It can be understood that when the chain 400 is running, its rollers 410 first enter the main contact section 212 under the guidance of the inlet section 211. The main contact section 212 mainly provides tension to the chain 400 and controls the tension and running trajectory of the chain 400. After the chain 400 rollers 410 enter the outlet section 213, they can leave under the guidance of the outlet section 213.

[0069] Furthermore, the radius of curvature of the main contact segment 212 is greater than that of the inlet segment 211 and the outlet segment 213.

[0070] Understandably, the load borne by the chain 400 when running along the tension surface 210 is mainly concentrated in the main contact section 212. This section uses a larger radius of curvature (compared to the lead section 211 and lead section 213), making the arc surface of the tension surface 210 smoother, which can increase its contact area with the rollers 410 of the chain 400 (the rollers 410 are cylindrical structures, and when the cylindrical rollers 410 contact the main contact section 212, it is a "line contact," but the essence of this "contact line" is: the "circular arc length" (along the extension direction of the main contact section 212) where the surface of the rollers 410 fits against the main contact section 212. This is called the "contact arc length" in the industry. The contact area between roller 410 and main contact section 212 is the contact arc length × the width of roller 410. The larger the radius of curvature of main contact section 212, the larger the contact arc length. Therefore, increasing the radius of curvature of main contact section 212 can increase its contact area with roller 410, thereby dispersing pressure and reducing the risk of local high pressure forming friction hotspots. This reduces the risk of rapid wear of main contact section 212, wear and flattening of chain 400 roller 410, and high temperature damage to the lubricating oil film, thus improving NVH (noise, vibration, and harshness) performance. It can improve the problem of local pressure concentration caused by insufficient contact area and small radius of curvature of the main contact section in traditional equal curvature tensioning surfaces, reduce local wear between tensioning surface 210 and chain 400 roller 410, and extend the service life of tensioning arm 200 and chain 400. The core function of the inlet section 211 is to guide the chain 400 to smoothly enter the tension surface 210, while the core function of the outlet section 213 is to guide the chain 400 to smoothly disengage from the tension surface 210. Both sections use a smaller radius of curvature than the main contact section 212, which allows for precise constraint on the movement posture of the chain 400, enabling the chain 400 to smoothly complete the entry and disengagement actions. In addition, as transitional sections for the operation of the chain 400, the inlet section 211 and outlet section 213 have short contact times and small loads. A smaller radius of curvature (compared to the main contact section 212) is sufficient to meet the basic guiding requirements, eliminating the need for redundant contact area due to a large curvature.

[0071] Furthermore, the larger radius of curvature of the main contact section 212 provides a more stable support wrap angle, effectively balancing the tension of the chain 400 across the entire engine speed range, reducing tension fluctuations, and ensuring that the chain 400 maintains a good fit with the tension surface 210 during the main load-bearing phase. This avoids problems such as chain skipping or looseness caused by sudden tension changes. Meanwhile, the small radii of curvature of the inlet section 211 and outlet section 213 precisely constrain the chain 400's entry and exit posture, preventing chain deviation and ensuring that the chain 400 always runs on a preset trajectory after entering the main contact section 212, further guaranteeing the stability of the main contact section 212 under load. This design allows the timing system to maintain stable operation under different conditions, including low and high speeds, reducing the risk of failure.

[0072] The radius of curvature of the inlet segment 211 is greater than or equal to 120 mm and less than or equal to 200 mm, the radius of curvature of the main contact segment 212 is greater than or equal to 350 mm and less than or equal to 550 mm, and the radius of curvature of the outlet segment 213 is greater than or equal to 120 mm and less than or equal to 200 mm. For example, the radius of curvature of the inlet segment 211 can be 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm or 200mm; the radius of curvature of the main contact segment 212 can be 350mm, 370mm, 390mm, 410mm, 420mm, 440mm, 460mm, 480mm, 500mm, 520mm, 530mm or 550mm; and the radius of curvature of the outlet segment 213 can be 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm or 200mm.

[0073] The guide section 211 has a small radius of curvature (relative to the main contact section 212), ranging from 120mm to 200mm. Like the tensioning arm 200, it guides the rollers 410 of the chain 400 along a preset trajectory, reducing impact and preventing lateral deviation. Specifically, the radius of curvature of the guide section 211 is within the range of 120mm–200mm. Within this range, when the rollers 410 of the chain 400 cut into the tensioning surface 210, the impact with the guide surface is reduced, improving the problem of lateral runout. It should be noted that the radius of curvature is related to the curvature of the curve; the smaller the radius of curvature, the more curved the curve. A guide section 211 with a small radius of curvature (less than 100mm) acts like a very steep slope. When the rollers 410 collide with the guide section 211, not only is the impact force large, but uneven force distribution can also cause lateral runout and even wear on the edges of the rollers 410. A larger radius of curvature in the guide section 211 (greater than 300 mm) will result in a smoother surface. This smoother surface will cause the roller 410 to travel a longer path. Specifically, the roller 410 will contact the guide section 211 earlier and travel a longer distance along it before entering the main contact section 212, thus increasing frictional work. By setting the radius of curvature of the guide section 211 within the range of 120 mm–200 mm, the problems associated with excessively small or large radii of curvature in the guide section 211 can be mitigated.

[0074] The main contact section 212 is the "main stress zone" of the chain 400. By increasing the radius of curvature (compared to the lead section 211 and lead section 213), the radius of curvature of the main contact section 212 is set in the range of 350mm-550mm. This can extend the contact area between the main contact section 212 and the chain 400 roller 410, thereby dispersing the pressure and reducing the risk of local high pressure forming friction hotspots. This reduces the risk of the main contact section 212 being worn quickly, the chain 400 roller 410 being worn flat, and the high temperature damaging the lubricating oil film, thereby improving NVH (noise, vibration, and harshness) performance.

[0075] The roller 410 of the chain 400 needs to disengage from the tensioning surface 210. By setting the radius of curvature of the guide section 213 within the range of 120mm–200mm, the roller 410 can disengage smoothly. It should be noted that the core task of the guide section 213 is to transmit the chain 400, which has been running smoothly through the main contact section 212, to the sprocket 300. Its radius of curvature is smaller than that of the main contact section 212, so the guide section 213 is more curved than the main contact section 212. The contact path of the roller 410 of the chain 400 along the guide section 213 will be smaller, thereby releasing the constraint on the roller 410 more quickly and allowing the roller 410 to disengage from the tensioning surface 210 more smoothly. At the same time, the smaller contact path of the roller 410 of the chain 400 along the guide section 213 will reduce frictional work. In addition, if the radius of curvature of the lead-out section 213 is less than 120mm, excessive bending will occur; when the roller 410 enters the lead-out section 213 (sharp bend) from the main contact section 212 (gentle arc surface), the direction of movement will change abruptly, which will cause the impact force to suddenly increase, increase noise, and accelerate the wear of the lead-out surface; while if the radius of curvature of the lead-out section 213 is greater than 200mm, the contact path of the roller 410 of the chain 400 along the lead-out section 213 will increase, thereby increasing the friction work.

[0076] The introductory segment 211 and the main contact segment 212 are smoothly connected by a surface with continuously changing curvature. It should be noted that the introductory segment 211 and the main contact segment 212 can be smoothly connected by a surface transition that satisfies the second-order geometric continuity condition.

[0077] It is understandable that the transition between the inlet segment 211 and the main contact segment 212 via a surface that satisfies the second-order geometric continuity condition means that the position, tangent direction, and rate of curvature change of these two surfaces at the connection point remain continuous, without any inflection points or curvature jumps. When the chain 400 roller 410 cuts into the main contact segment 212 from the inlet segment 211, the direction of motion and sliding acceleration will change smoothly along the transition surface, without the need for forced turning or sudden acceleration changes. This avoids the lateral impact caused by tangent offset and sudden curvature changes in traditional discontinuous transition connections, effectively suppressing the lateral jump and sway angle offset of the chain 400, and ensuring that the chain 400 enters the main contact segment 212 in a preset stable posture. Furthermore, the transition between the inlet section 211 and the main contact section 212 via a curved surface that satisfies the second-order geometrical continuity condition ensures that the movement trajectory of the chain 400 roller 410 in the transition area is free from "step-like" compression. The sliding state between the roller 410 and the tensioning surface 210 is smoother, and no additional sliding friction work is generated due to abrupt changes in the motion state. Understandably, the impact and vibration of the chain 400 roller 410 during the transition between the inlet section 211 and the main contact section 212 are significantly reduced. This not only reduces the collision noise between the chain 400 and the tensioning surface 210, but also reduces the transmission of vibration to the tensioning arm 200, effectively improving the overall NVH performance and enhancing the smoothness of engine operation.

[0078] Specifically, the tensioning surface 210 also includes a first transition section 214 connecting the inlet section 211 and the main contact section 212, wherein the first transition section 214 is a surface that satisfies the second-order geometric continuity condition.

[0079] Furthermore, the arc length L1 of the first transition section 214 is proportional to the pitch p of the chain 400. Specifically, L1 = k * n * p, where the coefficient k takes any integer value from 2 to 6, and n is the number of rows of the chain. In this way, when the chain 400 passes through the first transition section 214, the curvature change is gradually borne by multiple adjacent rollers 410, avoiding a sudden load on a single roller 410, thereby reducing the peak normal contact force and frictional work.

[0080] Furthermore, the main contact segment 212 and the lead segment 213 are smoothly connected by a surface with continuously changing curvature. It should be noted that the lead segment 213 and the main contact segment 212 can be smoothly connected by a surface transition that satisfies the second-order geometric continuity condition.

[0081] It is understandable that the transition between the leading segment 213 and the main contact segment 212 is achieved through a surface that satisfies the second-order geometric continuity condition. This means that the positions, tangent directions, and rates of curvature change of these two surfaces at the connection point remain continuous, without any inflection points or curvature jumps. When the chain 400 roller 410 enters the leading segment 213 from the main contact segment 212, its motion direction and sliding speed are smoothly adjusted along the transition surface. There is no need to force a turn due to a sudden change in trajectory, avoiding the lateral throwing force caused by tangent offset and sudden curvature changes in traditional discontinuous transition connections. This reduces the risk of the chain 400 getting stuck at the connection point and ensures that the chain 400 leaves in a preset stable posture. Furthermore, the transition between the lead-out section 213 and the main contact section 212 via a curved surface that satisfies the second-order geometrical continuity condition ensures that the chain 400 roller 410 experiences no step-like compression in the connection area between the main contact section 212 and the lead-out section 213. The sliding state between the roller 410 and the tension surface 210 remains consistently stable, preventing additional sliding friction work from abrupt changes in motion. Moreover, the transition between the lead-out section 213 and the main contact section 212 via a curved surface that satisfies the second-order geometrical continuity condition allows the chain 400 roller 410 to smoothly adjust its motion direction and sliding speed along the transition surface when entering the lead-out section 213 from the main contact section 212. This prevents the transmission of reverse interference forces to the main contact section 212, ensuring that the main contact section 212 maintains a stable support wrap angle and uniform pressure distribution, fully leveraging its high curvature load-bearing capacity. Furthermore, the impact and vibration of the chain 400 and roller 410 when passing through the transition area are greatly reduced, which not only reduces the contact noise between the tension surface 210 and the chain 400, but also reduces the vibration transmission efficiency, effectively improving the NVH performance of the entire timing system and enhancing the smoothness of engine operation.

[0082] Specifically, the tensioning surface 210 also includes a second transition section 215 connecting the main contact section 212 and the leading section 213. The second transition section 215 is a surface that satisfies the second-order geometric continuity condition.

[0083] Furthermore, the arc length L2 of the second transition section 215 is proportional to the pitch p of the chain 400. Specifically, L2 = k * n * p, where the coefficient k takes any integer value from 2 to 6, and n is the number of rows of the chain. In this way, when the chain 400 passes through the second transition section 215, the curvature change is gradually borne by multiple adjacent rollers 410, avoiding a sudden load on a single roller 410, thereby reducing the peak normal contact force and frictional work.

[0084] Specifically, along the extension direction of the tension surface 210, the entire tension surface 210 satisfies second-order geometric continuity.

[0085] Along the extension direction of the tension surface 210, the entire tension surface 210, consisting of the inlet segment 211, the main contact segment 212, and the outlet segment 213, satisfies the second-order geometric continuity condition. This means that the entire surface achieves continuous and abrupt changes in position, tangent direction, and rate of curvature change at any position. This is an advanced optimization of the segmented smooth connection, allowing the chain 400 to form an integrated smooth surface from the moment it enters the tension surface 210 to the moment it leaves the tension surface 210. This eliminates the curvature jumps and tangent offsets in any area of ​​the tension surface 210.

[0086] In the engine timing system, the tensioner arm 200, as the core guiding component of the chain 400, directly determines the operating performance of the timing system through the contact state between its tensioning surface 210 and the chain 400. Traditional tensioner arms 200 typically employ a planar structure design for their tensioning surface 210 (combined with...). Figure 10 and Figure 11 When the tensioning surface 210 contacts the roller 410 of the chain 400, a parallel contact surface is formed. Although this structure is easy to process, it has a series of insurmountable technical defects in actual engine operating conditions (speed fluctuation, load change, chain has degrees of freedom of movement). Moreover, the defects are superimposed to form a vicious failure cycle, which seriously affects the reliability of the timing system and the operating performance of the engine.

[0087] According to the classic Stribeck curve in the field of lubrication, the necessary geometric condition for the formation of a load-bearing oil film between friction pairs is that the two contact surfaces form a wedge angle. Only when a wedge angle exists can the lubricating oil be squeezed into the wedge gap and generate oil film pressure when the friction pairs slide relative to each other. This pressure can support the contact load, allowing the oil film to slightly separate the two contact surfaces, avoiding direct material contact, and thus achieving low-friction fluid lubrication or mixed lubrication. However, in the traditional tension arm 200, because its tensioning surface 210 is a plane, it forms a completely parallel contact surface when it contacts the chain 400. Even if the tension arm 200 and the chain 400 are immersed in lubricating oil and the surface is covered with lubricating oil, a load-bearing oil film cannot be formed. The lubricating oil can only adhere to the contact surface with a molecular-level thickness, which cannot generate oil film pressure, let alone support the contact load between the chain 400 and the tension arm 200.

[0088] In actual operating conditions, the contact lubrication system between the chain 400 and the traditional tension arm 200 (with a flat tensioning surface 210) is in a boundary lubrication state as described in the Stribeck curve for a long time: a large area is in direct contact between the tension arm 200 and the chain 400, with only localized oil films of molecular thickness and a high coefficient of friction. This lubrication state not only leads to a significant increase in the frictional resistance of the chain 400, but also becomes the core cause of all subsequent wear failures. Moreover, this defect is an inherent defect of the tensioning surface 210 of the tension arm 200 being flat, and cannot be fundamentally solved by simply adding lubricating oil or applying solid lubricating coatings.

[0089] In a traditional tension arm 200 (with a flat tensioning surface 210), the contact lubrication system between the chain 400 and the tension arm 200 is in a boundary lubrication state for a long time. As a result, the tension arm 200 will show obvious failure of the tensioning surface 210 within 10,000 to 30,000 kilometers of operation. After 50,000 to 100,000 kilometers of operation, severe wear such as material peeling, pitting, and spalling will occur. The wear failure is not a single type, but rather exhibits the superposition characteristics of adhesive wear and abrasive wear. Moreover, the various wear types promote each other, forming a vicious cycle of wear failure. Adhesive wear refers to the following: Under boundary lubrication conditions, the material surfaces of the tension arm 200 and the chain 400 are in direct contact. Due to friction, the local contact pressure and temperature increase significantly, causing the microscopic protrusions on the contact surfaces to stick together and tear. The material on the surface of the tension arm 200 is scraped off by the chain 400, forming pits and peeling areas of adhesive wear. Abrasive wear refers to the following: Material debris generated by adhesive wear and tiny impurities from the engine mix into the contact interface between the tension arm 200 and the chain 400, becoming "abrasive". As the chain 400 slides, it scrapes the contact surface, further aggravating the damage to the tension surface 210 of the tension arm 200. At the same time, the abrasive also causes wear on the chain 400, resulting in secondary wear failure. The combined effect of the above-mentioned types of wear significantly reduces the service life of the traditional tension arm 200 (tensioning surface 210 is a plane), generally only meeting the engine's short-term usage needs, and must be replaced later, increasing the engine's maintenance costs. Furthermore, the metal shavings generated by wear will mix into the engine lubricating oil, contaminating the lubrication system and affecting the normal operation of other engine components.

[0090] like Figure 8 , Figure 9As shown, based on the above reasons, in this application, the tensioning surface 210 is used to abut against one side of the chain 400 along the thickness direction of the chain 400. The chain 400 abutting against the tensioning surface 210 runs along the extension direction of the tensioning arm 200. The arrangement direction of the first side portion 201 and the second side portion 202 is the thickness direction of the tensioning arm 200. Both the thickness direction and the extension direction of the tensioning arm 200 are perpendicular to the width direction of the tensioning arm 200. The tensioning surface 210 is positioned parallel to both the thickness and width directions of the tensioning arm 200. Within the projection surface, the projection line formed by the tension surface 210 protrudes away from the second side portion 202 along the thickness direction of the tension arm 200. The projection line has a first endpoint 210a, a second endpoint 210b and a first protrusion 210c located between the first endpoint 210a and the second endpoint 210b, which are arranged along the width direction of the tension arm 200. The protrusion distance of the projection line gradually decreases along the direction from the first protrusion 210c to the first endpoint 210a and the direction from the first protrusion 210c to the second endpoint 210b.

[0091] It is understandable that the tensioning surface 210 has the shape shown above. The contact position between the tensioning surface 210 and the chain 400 forms a first wedge-shaped gap 600 on both sides along the width direction of the tensioning arm 200. Along the width direction of the tensioning arm 200, the width of the first wedge-shaped gap 600 increases as its distance from the contact position increases.

[0092] Through long-term observation and theoretical analysis of the failure phenomenon of the traditional tensioner arm 200 (tensioning surface 210 is a plane), the inventors discovered that the root cause of all problems in the existing technology is not auxiliary factors such as machining accuracy or material properties, but rather the inability of the parallel contact surface to form a load-bearing oil film. This results in the lubrication system being in a high-friction boundary lubrication state for a long time, which is an inherent defect of the traditional tensioner arm 200. According to the conclusions of the Stribeck lubrication curve, the necessary geometric condition for the formation of a load-bearing oil film is the formation of a wedge-shaped gap on the contact surface. Therefore, the key to solving the lubrication failure problem is to change the contact surface between the chain 400 and the tensioner arm 200 from a "parallel structure" to a "structure with a wedge-shaped gap," providing a geometric basis for the insertion of lubricating oil and the generation of oil film pressure, thereby allowing the contact lubrication system to transform from boundary lubrication to a low-friction mixed lubrication state. To achieve a wedge-shaped angle while ensuring the guiding and load-bearing functions of the tension arm 200, the inventors proposed changing the shape of the tension surface 210 so that gaps are formed on both sides of the contact point between the tension surface 210 and the chain 400 along the width direction of the tension arm 200. Furthermore, the width of these gaps increases with the distance from the contact point along the width direction of the tension arm 200. Essentially, this structural design involves constructing a first wedge-shaped gap 600 along the width direction of the tension arm 200 between the chain 400 and the tension surface 210. In this first wedge-shaped gap 600, the contact point between the chain 400 and the tension surface 210 is the narrow end, and the end furthest from the contact point is the wide end. When the chain 400 runs along the tension surface 210, lubricating oil is naturally squeezed into the first wedge-shaped gap 600, generating oil film pressure and forming a load-bearing oil film.

[0093] In this application, a first wedge-shaped gap 600 is constructed, allowing the contact lubrication system between the chain 400 and the tension arm 200 to stably maintain a low-friction mixed lubrication state as shown in the Stribeck curve, moving away from the traditional boundary lubrication state, thus fundamentally solving the lubrication failure problem. Specifically, in the first wedge-shaped gap 600, the contact position between the chain 400 and the tension surface 210 is the narrow end of the first wedge-shaped gap 600, and the end away from the contact position is the wide end of the first wedge-shaped gap 600. When the chain 400 runs along the extension direction of the tension surface 210, the chain 400 and the tension surface 210 slide relative to each other. Under the action of relative sliding, the lubricating oil is naturally squeezed into the narrow end of the first wedge-shaped gap 600. As the lubricating oil is continuously squeezed in, a continuous and stable oil film pressure is generated in the first wedge-shaped gap 600. This pressure can effectively support the contact load between the chain 400 and the tension arm 200, allowing the oil film to slightly separate the chain 400 from the tension surface 210, forming a load-bearing oil film. The formation of this load-bearing oil film transforms the lubrication system between the chain 400 and the tensioner arm 200 from boundary lubrication to mixed lubrication: the contact area is partially supported by the oil film, with only slight material surface contact in certain areas, significantly reducing the coefficient of friction (compared to boundary lubrication). This optimization of the lubrication system not only significantly reduces the frictional resistance of the chain 400, reducing engine power loss and improving fuel economy, but also fundamentally addresses the core causes of wear failure. Understandably, in the mixed lubrication state, the load-bearing oil film slightly separates the chain 400 from the tensioning surface 210, avoiding direct contact between the two material surfaces. This eliminates the conditions for adhesive wear at the source, and the surface of the tensioning arm 200 will no longer show pits and peeling caused by material adhesion and tearing. In addition, the low coefficient of friction in the mixed lubrication state significantly reduces the generation of frictional heat, avoiding material softening and debris shedding caused by excessively high local temperatures. Furthermore, the first wedge-shaped gap 600 provides a channel for the flow of lubricating oil, and the small amount of tiny debris generated by wear will be carried away by the lubricating oil, preventing the formation of abrasives at the contact interface, effectively inhibiting the occurrence of abrasive wear, and also avoiding secondary wear of the chain 400 by abrasives.

[0094] In the projection plane parallel to the thickness and width directions of the tension arm 200, the projection line formed by the tension surface 210 is arc-shaped. Specifically, the tension surface 210 is an arc surface, and along the width direction of the tension arm 200, the two side edges of the tension surface 210 gradually protrude away from the middle of the tension surface 210 towards the second side 202.

[0095] Understandably, the tensioning surface 210 has its highest point at the center along the width of the tensioning arm 200, and both sides gradually slope towards the second side 202 with an arc-shaped surface. This arc-shaped profile is a continuous and smooth curved surface structure. Thus, when the chain 400 contacts the tensioning surface 210, a first wedge-shaped gap 600 is formed along the width of the tensioning arm 200. Specifically, under its own weight and tension, the chain 400 forms a stable contact with the middle part of the tensioning surface 210 protruding in a preset direction. This middle contact position is the narrow end of the first wedge-shaped gap 600. The two sides of the tensioning surface 210 are inclined in an arc towards the second side 202, forming a gap extending in the width direction between the chain 400 and the tensioning surface 210. The width of this gap gradually increases as it moves away from the middle contact position, forming the wide end of the first wedge-shaped gap 600, thus forming a complete first wedge-shaped gap 600 structure. When the chain 400 runs along the length direction of the tensioning arm 200, the chain 400 and the tensioning surface 210 slide relative to each other. Under the shearing action of the relative sliding, the engine lubricating oil is continuously squeezed into the narrow end of the first wedge-shaped gap 600. As the lubricating oil continues to flow in, a stable hydrodynamic oil film pressure is generated in the gap. This pressure can effectively support the contact load between the chain 400 and the tensioning arm 200, and micro-separate the chain 400 from the surface of the tensioning surface 210.

[0096] In the thickness direction of the tension arm 200, the distance H1 between the first end point 210a (second end point 210b) and the first protrusion 210c is greater than or equal to 0.2mm and less than or equal to 0.6mm. For example, the value of H1 can be, but is not limited to, 0.2mm, 0.3mm, 0.4mm, 0.5mm or 0.6mm.

[0097] In addition, in this application, the projection line formed by the tensioning surface 210 in the projection plane parallel to the thickness and width directions of the tensioning arm 200 is arc-shaped. No matter what form of swing or offset (lateral offset, circumferential swing, or combined sway) occurs in the chain 400 during the operation of the engine timing system, it can always naturally form a continuous first wedge gap 600 when it contacts the tensioning surface 210, which has high reliability.

[0098] Furthermore, when the rollers 410 of the chain 400 run on the tensioning surface 210, the rollers 410 mainly contact the central protrusion of the tensioning surface 210. This central protrusion acts as a "centering structure" for the rollers 410 of the chain 400. When the chain 400 deviates laterally, it is guided back to the center by the inclined portion of the curved surface, reducing the yaw angle, thereby weakening vibration, reducing noise, and improving engine quietness. In addition, the "centering structure" of the central protrusion of the tensioning surface 210 also forces the chain 400 to run along the central trajectory, reducing the risk of poor engagement between the chain 400 and the sprocket 300 due to lateral deviation. Simultaneously, the stable contact reduces transient jumps in the chain 400, lowering the risk of skipped teeth. Figure 10 and Figure 11 Furthermore, in the traditional design, the tensioning surface 210 is a planar structure. When the chain 400 tilts, the edge of the chain 400 will directly contact the tensioning surface 210. At this time, the edge of the chain 400 mainly bears the pressure, which will lead to accelerated wear on the edge of the chain 400 and generate greater noise. (Refer to Figure 8 for more details.) Figure 9 In this application, the tensioning surface 210 is an arc shape that protrudes from the middle away from the second side 202. Even if the chain 400 is tilted, when the chain 400 moves along the tensioning surface 210, it is difficult for the edge part of the chain 400 to directly contact the tensioning surface 210. This can reduce the risk of accelerated wear on the edge part of the chain 400 and improve the noise problem.

[0099] Furthermore, a straight line located at the exact center of the first endpoint 210a and the second endpoint 210b, and parallel to the thickness direction of the tensioning arm 200, is defined as a reference line. In the projection plane parallel to the thickness and width directions of the tensioning arm 200, the projection line formed by the tensioning surface 210 is symmetrically arranged with this reference line as the axis of symmetry.

[0100] Understandably, when the chain 400 shifts laterally due to tension fluctuations or vibrations, regardless of whether it shifts towards the first end point 210a or the second end point 210b, the lateral guiding force on the chain 400 is completely consistent in magnitude and symmetrical in trend. This ensures that the chain 400 is pulled back to the center of the tensioning surface 210 with the same corrective force, preventing situations where one side has a strong or weak corrective force. Furthermore, when the chain 400 contacts the highest point of the protrusion on the tensioning surface 210, the two first wedge-shaped gaps 600 formed are symmetrical. The insertion and flow of lubricating oil within the two first wedge-shaped gaps 600 remain balanced, reducing the risk of oil film rupture due to an excessively small first wedge-shaped gap 600 on one side, or insufficient lubrication due to an excessively large gap on one side.

[0101] Furthermore, within the projection plane parallel to the thickness and width directions of the tension arm 200, the projection line formed by the tension surface 210 is a curve satisfying second-order connection. Thus, this curve is not only smooth in itself, but its curvature (second derivative) also changes smoothly without any abrupt inflection points. Consequently, along the arc length direction of the tension surface 210, there are no "inflection points" or "zigzag" connections. Along the arc length direction of the tension surface 210, its curvature changes smoothly and gradually from the central high point to the two side edges. When the chain 400 sways laterally, the force state changes gradually without abrupt force changes, which can reduce sudden changes in impact load during the operation of the chain 400, lower the vibration frequency of the chain 400, suppress impact noise, and improve NVH performance. In addition, when the chain 400 shifts laterally, it will be gradually guided back to the center along the smooth tension surface 210, improving the problem of jamming.

[0102] like Figure 7 As shown, along the extension direction of the tension arm 200, the tension surface 210 satisfies second-order geometric continuity. Thus, the tension surface 210 exhibits a smooth transition without any local abrupt changes along the extension direction of the tension arm 200, and has no inflection points indicating abrupt curvature changes. After entering the rail, the chain 400 always runs along a smooth trajectory without abrupt contact changes, which can reduce the impact load on the chain 400 during operation, improve noise issues, and enhance NVH performance. Furthermore, the chain 400 operates with the centerline of the tension surface 210 as its target trajectory. The second-order continuity of the tension surface 210 along the extension direction of the tension arm 200 ensures a smooth and unbiased trajectory, resulting in a smooth and gradual change in its guiding direction. When the chain 400 deviates laterally, it is gradually pulled back to the center by the tension surface 210. Simultaneously, the smooth centerline trajectory avoids abrupt path changes when the chain 400 engages with the sprocket 300, reducing the risk of tooth skipping.

[0103] The end of the guide section 211 furthest from the main contact section 212 is smoothly connected to an arc-shaped guide surface. Along the opposite direction of the chain 400's running direction (which abuts against the tension surface 210), the arc-shaped guide surface gradually approaches the second side portion 202. The arc-shaped guide surface guides the entry of the rollers 410 of the chain 400. The arc-shaped guide surface can be formed using a rounded corner method.

[0104] Understandably, if the end of the tensioning surface 210 furthest from the main contact section 212 lacks an arc-shaped guide surface (such as a right angle or no transition), the roller 410 of the chain 400 may contact the entry end of the edge of the tensioning surface 210 in a hard collision manner, causing strong impact loads and vibrations. The arc-shaped guide surface, in essence, is an "entry guide ramp," whose arc-shaped profile allows the roller 410 of the chain 400 to contact the tensioning surface 210 in a "gradual" manner, with the force smoothly increasing from zero to present, without abrupt force changes. Simultaneously, the arc-shaped guide surface smoothly connects to the arc-shaped guide surface of the tensioning surface 210, ensuring that the chamfer and the main body of the tensioning surface 210 are without steps or inflection points, preventing the roller 410 of the chain 400 from encountering another impact after passing the chamfer.

[0105] Specifically, the connection between the arc-shaped guide surface and the end of the guide segment 211 away from the main contact segment 212 satisfies second-order geometric continuity, thus achieving a smooth transition at the connection between the arc-shaped guide surface and the tension surface 210.

[0106] Among them, the arc-shaped guide surface itself is a second-order continuous surface. For example, the arc-shaped guide surface itself is a second-order continuous surface. In this way, the surface profile of the arc-shaped guide surface has no inflection points and no curvature abrupt changes. The slope (first derivative) and curvature (second derivative) are both in a smooth and gradual state, forming a smooth guide surface without hard edges and no breaks, which can eliminate contact interference when the chain enters the rail at 400 degrees.

[0107] like Figure 6 As shown, in some embodiments, the tensioning arm 200 also has a connecting portion 203 connected between the first side portion 201 and the second side portion 202. The connecting portion 203 is provided with a first reinforcing rib 220 to improve the overall strength and reduce the risk of deformation of the tensioning arm 200.

[0108] In some embodiments, the tensioning surface 210 is provided with retention textures for lubricating oil retention; wherein the depth of the grooves formed between the retention textures is between 10μm and 30μm. It is understood that when the chain 400 is in contact with the tensioning surface 210, the lubricating oil is easily thrown away or squeezed out of the contact area due to centrifugal force and friction. The retention textures can store lubricating oil and continuously replenish the contact position between the chain 400 and the tensioning surface 210 during dynamic operation, ensuring that a continuous and uniform fluid lubrication film is always formed in the contact area, completely avoiding direct hard contact between the chain 400 roller 410 and the tensioning surface 210, and improving various wear problems caused by dry friction.

[0109] In other embodiments, the tensioning surface 210 is provided with a retention groove for lubricating oil, the depth of which is between 10μm and 30μm. Similarly, the retention groove can store lubricating oil, and can continuously replenish lubricating oil to the contact position between the chain 400 and the tensioning surface 210 during dynamic operation, ensuring that a continuous and uniform fluid lubrication film is always formed in the contact area, completely avoiding direct hard contact between the chain 400 roller 410 and the tensioning surface 210, and improving various wear problems caused by dry friction.

[0110] like Figure 1 As shown, in the engine timing system, the guide rail 500, as the core guiding component of the chain 400, directly determines the operating performance of the timing system through the contact state between its guide surface and the chain 400. Traditional guide rails 500 employ a planar structure design for their guide surfaces (e.g., Figure 12 and Figure 13 As shown), when the guide surface contacts the roller 410 of the chain 400, a parallel contact surface is formed. Although this structure has the advantage of simple processing, in actual engine operating conditions (speed fluctuation, load change, chain has degrees of freedom of movement), there are a series of insurmountable technical defects. Moreover, the defects are superimposed to form a vicious failure cycle, which seriously affects the reliability of the timing system and the operating performance of the engine.

[0111] According to the classic Stribeck curve in lubrication, the necessary geometric condition for the formation of a load-bearing oil film between friction pairs is that the two contact surfaces form a wedge angle. Only when a wedge angle exists can the lubricating oil be squeezed into the wedge gap and generate oil film pressure when the friction pairs slide relative to each other. This pressure can support the contact load, allowing the oil film to slightly separate the two contact surfaces, avoiding direct material contact, and thus achieving low-friction fluid lubrication or mixed lubrication. However, in the traditional guide rail 500, because its guide surface is flat, it forms a completely parallel contact surface when it contacts the chain 400. Even if the guide rail 500 and chain 400 are immersed in lubricating oil and the surface is covered with lubricating oil, a load-bearing oil film cannot be formed. The lubricating oil can only adhere to the contact surface with a molecular-level thickness, unable to generate oil film pressure, let alone support the contact load between the chain 400 and the guide rail 500.

[0112] In actual operating conditions, the contact lubrication system between the chain 400 and the traditional guide rail 500 (with a planar guide surface) is in a boundary lubrication state as described in the Stribeck curve for a long time: a large area is in direct contact between the guide rail 500 and the chain 400, with only localized oil films of molecular thickness and a relatively high coefficient of friction. This lubrication state not only leads to a significant increase in the frictional resistance of the chain 400, but also becomes the core cause of all subsequent wear and failure. Moreover, this defect is an inherent defect of the planar guide surface of the guide rail 500, and cannot be fundamentally solved by simply adding lubricating oil or applying solid lubricating coatings.

[0113] In traditional guide rails 500 (with a flat guide surface), the contact lubrication system between the chain 400 and the guide rail 500 is in a boundary lubrication state for a long time. Traditional guide rails 500 will show obvious guide surface failure within 10,000 to 30,000 kilometers of operation. After 50,000 to 100,000 kilometers of operation, severe wear such as material peeling, pitting, and spalling will occur. The wear failure is not a single type, but exhibits the superposition characteristics of adhesive wear, abrasive wear, etc., and the various wear types promote each other, forming a vicious cycle of wear failure. Adhesive wear refers to the direct contact between the material surfaces of the guide rail 500 and the chain 400 under boundary lubrication conditions. Local contact pressure and temperature increase significantly due to friction, causing microscopic protrusions on the contact surfaces to adhere and tear. The material on the guide rail 500 surface is scraped off by the chain 400, forming pits and spalling areas of adhesive wear. Abrasive wear refers to the mixing of material debris generated by adhesive wear and minute impurities from the engine into the contact interface between the guide rail 500 and the chain 400, becoming "abrasive." As the chain 400 slides, it scrapes the contact surface, further aggravating damage to the guide surface of the guide rail 500. Simultaneously, the abrasive also causes wear on the chain 400, leading to secondary wear failure. The superposition of these types of wear significantly reduces the service life of the traditional guide rail 500 (with a flat guide surface), generally only meeting the engine's short-term operating needs, requiring replacement later. This increases engine maintenance costs, and the metal debris generated by wear mixes into the engine lubricating oil, contaminating the lubrication system and affecting the normal operation of other engine components.

[0114] like Figure 14 As shown, based on the above-mentioned problems, an embodiment of this application provides a guide rail 500 having a third side portion 501 and a fourth side portion 502 disposed opposite to the third side portion 501. Specifically, the guide rail 500 is used to contact the chain 400, thereby guiding the chain 400. The third side portion 501 of the guide rail 500 is used to directly contact the chain 400 and guide the chain 400, while the fourth side portion 502 of the guide rail 500 is the side of the guide rail 500 facing away from the chain 400.

[0115] Combination Figure 14 and Figure 15 Furthermore, the third side portion 501 has a guide surface 510 for abutting against one side of the chain 400 along the thickness direction of the chain 400. It is understood that the guide surface 510 is the surface of the third side portion 501 facing away from the fourth side portion 502. The chain 400 in contact with the guide surface 510 can run along the extension direction of the guide surface 510.

[0116] It should be noted that the arrangement direction of the third side 501 and the fourth side 502 is the thickness direction of the guide rail 500, and the thickness direction and the extension direction of the guide rail 500 are both perpendicular to the width direction of the guide rail 500.

[0117] Combination Figure 15 and Figure 16 Furthermore, in the projection plane parallel to the thickness and width directions of the guide rail 500, the projection line formed by the guide surface 510 protrudes away from the fourth side 502 along the thickness direction of the guide rail 500. The projection line has a third end point 511, a fourth end point 512 and a second protrusion 513 located between the third end point 511 and the fourth end point 512, and the protrusion distance of the projection line gradually decreases along the direction from the second protrusion 513 to the third end point 511 and the direction from the second protrusion 513 to the fourth end point 512.

[0118] It is understandable that the guide surface 510 has the shape shown above. The contact position between the guide surface 510 and the chain 400 has a second wedge-shaped gap 700 on both sides along the width direction of the guide rail 500. Along the width direction of the guide rail 500, the width of the second wedge-shaped gap 700 increases as its distance from the contact position increases.

[0119] Through long-term observation and theoretical analysis of the failure phenomena of traditional guide rails 500 (with a planar guide surface), the inventors discovered that the root cause of all problems in existing technologies is not auxiliary factors such as machining accuracy or material properties, but rather the inability of parallel contact surfaces to form a load-bearing oil film. This results in the lubrication system being in a high-friction boundary lubrication state for a long time, which is an inherent defect of traditional guide rails 500. According to the conclusions of the Stribeck lubrication curve, the necessary geometric condition for the formation of a load-bearing oil film is the formation of a wedge-shaped gap on the contact surface. Therefore, the key to solving the lubrication failure problem is to change the contact surface between the chain 400 and the guide rail 500 from a "parallel structure" to a "structure with a wedge-shaped gap," providing a geometric basis for the insertion of lubricating oil and the generation of oil film pressure, thereby transforming the contact lubrication system from boundary lubrication to a low-friction mixed lubrication state. To achieve the wedge-shaped angle while ensuring the guiding and load-bearing functions of the guide rail 500, the inventors proposed changing the shape of the guide surface 510 so that the contact position between the guide surface 510 and the chain 400 forms gaps on both sides along the width direction of the guide rail 500, and the width of the gap increases with the distance from the contact position along the width direction of the guide rail 500. The essence of this structural design is to construct a second wedge-shaped gap 700 along the width direction of the guide rail 500 between the chain 400 and the guide surface 510. In the second wedge-shaped gap 700, the contact position between the chain 400 and the guide surface 510 is the narrow end of the second wedge-shaped gap 700, and the end away from the contact position is the wide end of the second wedge-shaped gap 700. When the chain 400 runs along the guide surface 510, lubricating oil is naturally squeezed into the second wedge-shaped gap 700, generating oil film pressure and forming a load-bearing oil film.

[0120] In this application, a second wedge-shaped gap 700 is constructed, allowing the contact lubrication system between the chain 400 and the guide rail 500 to stably maintain a low-friction mixed lubrication state as shown in the Stribeck curve, moving away from the traditional boundary lubrication state, thus fundamentally solving the lubrication failure problem. Specifically, in the second wedge-shaped gap 700, the contact position between the chain 400 and the guide surface 510 is the narrow end of the second wedge-shaped gap 700, and the end away from the contact position is the wide end of the second wedge-shaped gap 700. When the chain 400 runs along the extension direction of the guide surface 510, the chain 400 and the guide surface 510 slide relative to each other. Under the action of relative sliding, the lubricating oil is naturally squeezed into the narrow end of the second wedge-shaped gap 700. As the lubricating oil is continuously squeezed in, a continuous and stable oil film pressure is generated in the second wedge-shaped gap 700. This pressure can effectively support the contact load between the chain 400 and the guide rail 500, allowing the oil film to slightly separate the chain 400 from the guide surface 510, forming a load-bearing oil film. The formation of this load-bearing oil film transforms the lubrication system between the chain 400 and the guide rail 500 from boundary lubrication to hybrid lubrication: the contact area is partially supported by the oil film, with only slight material surface contact in certain areas, significantly reducing the coefficient of friction (compared to boundary lubrication). This optimization of the lubrication system not only significantly reduces the frictional resistance of the chain 400, reducing engine power loss and improving fuel economy, but also fundamentally addresses the core causes of wear failure. Understandably, in the mixed lubrication state, the load-bearing oil film slightly separates the chain 400 from the guide surface 510, avoiding direct contact between the two material surfaces. This eliminates the conditions for adhesive wear at the source, and the guide rail 500 surface will no longer show pits and peeling caused by material adhesion and tearing. In addition, the low coefficient of friction in the mixed lubrication state significantly reduces the generation of frictional heat, avoiding material softening and debris shedding caused by excessively high local temperatures. Furthermore, the second wedge-shaped gap 700 provides a channel for the flow of lubricating oil, and the small amount of tiny debris generated by wear will be carried away by the lubricating oil, preventing the formation of abrasives at the contact interface, effectively inhibiting the occurrence of abrasive wear, and also avoiding secondary wear of the chain 400 by abrasives.

[0121] Combination Figure 15 and Figure 16 In the projection plane parallel to the thickness and width directions of the guide rail 500, the projection line formed by the guide surface 510 is arc-shaped. Specifically, the guide surface 510 is an arc surface, and along the width direction of the guide rail 500, the two side edges of the guide surface 510 gradually protrude away from the center of the guide surface 510 towards the fourth side 502.

[0122] It is understood that the guide surface 510 has its highest point of protrusion at the middle of the width direction of the guide rail 500, and its two sides gradually slope towards the fourth side 502 with an arc-shaped surface. This arc-shaped profile is a continuous and smooth curved surface structure. Thus, when the chain 400 contacts the guide surface 510, a second wedge-shaped gap 700 is formed along the width direction of the guide rail 500. Specifically, under its own weight and tension, the chain 400 forms a stable contact with the center of the guide surface 510 protruding in a preset direction. This center contact position is the narrow end of the second wedge-shaped gap 700. The guide surface 510 is inclined arc-shaped towards the fourth side 502 on both sides, forming a gap extending in the width direction between itself and the chain 400. The width of this gap gradually increases as it moves away from the center contact position, forming the wide end of the second wedge-shaped gap 700, thus forming a complete second wedge-shaped gap 700 structure. When the chain 400 runs along the length of the guide rail 500, the chain 400 and the guide surface 510 slide relative to each other. Under the shearing action of the relative sliding, the engine lubricating oil is continuously squeezed into the narrow end of the second wedge-shaped gap 700. As the lubricating oil continues to flow in, a stable hydrodynamic oil film pressure is generated in the gap. This pressure can effectively support the contact load between the chain 400 and the guide rail 500, and micro-separate the chain 400 from the surface of the guide surface 510.

[0123] In the thickness direction of the guide rail 500, the distance H2 between the third end point 511 (fourth end point 512) and the second protrusion 513 is greater than or equal to 0.2 mm and less than or equal to 0.6 mm. For example, the value of H2 can be, but is not limited to, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or 0.6 mm.

[0124] Combination Figure 15 and Figure 16 In addition, in this application, the projection line formed by the guide surface 510 in the projection plane parallel to the thickness and width directions of the guide rail 500 is arc-shaped. No matter what form of swing or offset (lateral offset, circumferential swing, or combined sway) occurs in the chain 400 during the operation of the engine timing system, it can always naturally form a continuous second wedge gap 700 when it contacts the guide surface 510, which has high reliability.

[0125] Furthermore, when the rollers 410 of the chain 400 run on the guide surface 510, the rollers 410 mainly contact the central protrusion of the guide surface 510. This central protrusion of the guide surface 510 acts as a "centering structure" for the rollers 410 of the chain 400. When the chain 400 deviates laterally, it is guided back to the center by the inclined portion of the curved surface, reducing the yaw angle, thereby weakening vibration, reducing noise, and improving engine quietness. In addition, the "centering structure" of the central protrusion of the guide surface 510 also forces the chain 400 to run along the central trajectory, reducing the risk of poor engagement between the chain 400 and the sprocket 300 due to lateral deviation. Simultaneously, the stable contact reduces transient jumps in the chain 400, lowering the risk of skipped teeth. Figure 12 and Figure 13 Furthermore, in traditional designs, the guide surface is a planar structure. When the chain 400 tilts, its edge directly contacts the guide surface 510. At this point, the edge of the chain 400 primarily bears the pressure, leading to accelerated wear on the edge and increased noise. Combined with... Figure 15 and Figure 16 In this application, the guide surface 510 is an arc shape that protrudes from the middle of the fourth side 502. Even if the chain 400 is tilted, it is difficult for the edge of the chain 400 to directly contact the guide surface 510 when the chain 400 moves along the guide surface 510. This can reduce the risk of accelerated wear on the edge of the chain 400 and improve the noise problem.

[0126] Furthermore, within the projection plane parallel to the thickness and width directions of the guide rail 500, the projection line formed by the guide surface 510 is a curve satisfying second-order continuity. Thus, this curve is not only smooth itself, but its curvature (second derivative) also changes smoothly without any abrupt inflection points. Consequently, along the arc length of the guide surface 510, there are no "inflection points" or "zigzag" connections. Along the arc length of the guide surface 510, its curvature changes smoothly and gradually from the central high point to the two side edges. When the chain 400 sways laterally, the force state changes gradually without abrupt force changes, which can reduce sudden changes in impact load during the operation of the chain 400, lower the vibration frequency of the chain 400, suppress impact noise, and improve NVH performance. In addition, when the chain 400 deviates laterally, it will be gradually guided back to the center along the smooth guide surface 510, improving the problem of jamming.

[0127] like Figure 14As shown, along the extension direction of the guide rail 500, the guide surface 510 satisfies second-order continuity. Thus, the guide surface 510 exhibits a smooth transition without any local abrupt changes in curvature along the extension direction of the guide rail 500, and has no inflection points indicating abrupt curvature changes. After entering the rail, the chain 400 always runs along a smooth trajectory without abrupt contact changes, which can reduce the impact load on the chain 400 during operation, improve noise issues, and enhance NVH performance. Furthermore, the chain 400 operates with the centerline of the guide surface 510 as its target trajectory. The second-order continuity of the guide surface 510 along the extension direction of the guide rail 500 ensures a smooth and unbiased trajectory, resulting in a smooth and gradual change in its guiding direction. When the chain 400 deviates laterally, it is gradually pulled back to the center by the guide surface 510. Simultaneously, the smooth centerline trajectory avoids abrupt changes in the path when the chain 400 engages with the sprocket 300, reducing the risk of tooth skipping.

[0128] Furthermore, a straight line located at the exact center of the third endpoint 511 and the fourth endpoint 512, and parallel to the thickness direction of the guide rail 500, is defined as a reference line. In the projection plane parallel to the thickness and width directions of the guide rail 500, the projection line formed by the guide surface 510 is symmetrically arranged with the reference line as the axis of symmetry.

[0129] Understandably, when the chain 400 shifts laterally due to tension fluctuations or vibrations, regardless of whether it shifts towards the third end point 511 or the fourth end point 512, the lateral guiding force on the chain 400 is completely consistent in magnitude and symmetrical in trend. This ensures that the chain 400 is pulled back to the center of the guide surface 510 with the same corrective force, preventing situations where one side has a strong or weak corrective force. Furthermore, when the chain 400 contacts the highest point of the protrusion on the guide surface 510, the two second wedge-shaped gaps 700 formed are symmetrical. The insertion and flow of lubricating oil within the two second wedge-shaped gaps 700 remain balanced, reducing the risk of oil film rupture due to an excessively small second wedge-shaped gap 700 on one side, or insufficient lubrication due to an excessively large gap on one side.

[0130] Combination Figure 1 and Figure 14 Furthermore, along the running direction of the chain 400 in contact with the guide surface 510, the radius of curvature of the extension path of the guide surface 510 gradually increases. It can be understood that a larger radius of curvature of the guide surface 510 represents a smoother surface. Specifically, along the running direction of the chain 400 in contact with the guide surface 510, the radius of curvature of the extension path of the guide surface 510 continuously changes from R1 = 900mm–1500mm to R2 = 1300mm–5000mm.

[0131] Understandably, the radius of curvature directly determines the curvature of the guide surface 510's extension path. R1 is 900mm-1500mm, which is a small curvature range, corresponding to a slightly curved shape at the entrance end of the guide surface 510. R2 is 1300mm-5000mm, which is a large curvature range, corresponding to the smoothest shape at the exit end of the guide surface 510. The continuous change from R1 to R2 means that the curvature of the guide surface 510 gradually and smoothly decreases along the running direction of the chain 400. The arc curvature of the extension path has no abrupt changes, no inflection points, and no hard edges, forming a continuous and smooth arc guide path.

[0132] Understandably, the guide surface 510 has an inlet end 510a and an outlet end 510b arranged sequentially along the running direction of the chain 400 that contacts the guide surface 510. When the rollers 410 of the chain 400 enter the rail, they are pulled by the sprocket 300 and subjected to the pre-tension force of the tensioner 100, and are in a transitional stage from a relatively free state to a constrained state of the guide rail 500. At this time, the inlet end of the guide surface 510 has a slightly curved shape with a small radius of curvature. Its curvature matches the initial movement trajectory of the rollers 410 of the chain 400 when entering the rail, which allows the rollers 410 of the chain 400 to quickly form a tight and uniform contact with the guide surface 510, avoiding the problems of poor initial contact, slippage and deviation of the chain 400 when entering the rail due to an overly gentle path. Meanwhile, the slightly curved shape ensures that the contact area between the chain 400 and the guide surface 510 is not too large when the chain 400 enters the rail, providing a good contact foundation for the initial formation of the lubricating oil film and avoiding localized dry friction caused by poor contact between the chain 400 roller 410 and the guide surface 510. After the chain 400 roller 410 enters the rail, it enters a stable operating phase, and the contact load gradually stabilizes with the operating state. At this time, the radius of curvature of the guide surface 510 continuously increases, and the degree of path curvature gradually decreases. This gradual process allows the normal contact stress between the chain 400 and the guide surface 510 to be released gradually and evenly along the operating direction, and the contact stress decreases synchronously and steadily, avoiding instantaneous stress surges or drops. At the same time, the continuous curvature change ensures that the sliding of the chain 400 roller 410 on the guide surface 510 is always a smooth sliding motion, with no abrupt changes in contact position and contact area, completely avoiding changes in contact state caused by sudden curvature changes, and thus eliminating the generation of instantaneous normal pressure peaks.

[0133] In some embodiments, a reinforcing area is provided at the highest protruding position of the fourth side 502 of the guide surface 510 opposite to the guide rail 500. The structural reinforcement can be achieved by surface strengthening of the material, local geometric thickening, or wear-resistant lining. Since the protruding high point is the main contact point between the chain 400 and the guide rail 500, the normal contact pressure it bears is significantly higher than that on both sides. By providing a reinforcing area at the protruding high point, the load generated by the high-frequency vibration of the chain 400 can be effectively resisted, and the durability of the guide rail 500 can be improved.

[0134] In some embodiments, the guide surface 510 is coated with a lubricating coating, such as a PTFE (polytetrafluoroethylene) or MoS2 (molybdenum disulfide) coating, which has a low coefficient of friction and can reduce the frictional resistance between the chain 400 and the guide rail 500.

[0135] Furthermore, the guide surface 510 is provided with a texture, which can improve the retention of the lubricating coating. The width of the texture can be set between 0.01 mm and 0.3 mm, the depth can be set between 5 μm and 12 μm, and the spacing can be set between 0.3 mm and 0.7 mm.

[0136] Combination Figure 14 , Figure 17 and Figure 18 In some embodiments, the guide rail 500 has an inlet arc surface 520 located at the inlet end 510a away from the outlet end 510b. The inlet arc surface 520 is smoothly connected to the inlet end 510a of the guide surface 510. Along the opposite direction of the running direction of the chain 400 that abuts against the guide surface 510, the inlet arc surface 520 gradually approaches the fourth side portion 502. The inlet arc surface 520 provides guidance for the entry of the rollers 410 of the chain 400. The inlet arc surface 520 can be formed by rounding corners. The arc length of the inlet arc surface 520 can be 4mm-12mm; for example, the arc length of the inlet arc surface 520 can be 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, or 12mm.

[0137] Understandably, if the inlet end 510a of the guide surface 510 lacks a guide arc surface 520 (e.g., a right angle or no transition), the roller 410 of the chain 400 will contact the inlet end 510a of the guide surface 510 edge with a hard impact, causing strong impact loads and vibrations. The guide arc surface 520, essentially an "entry guide ramp," has an arc-shaped profile that allows the roller 410 of the chain 400 to contact the guide surface 510 in a "gradual" manner, with the force smoothly increasing from zero to present, without abrupt force changes. Simultaneously, the guide arc surface 520 smoothly connects to the guide arc surface 520 of the guide surface 510, ensuring that the chamfer and the main body of the guide surface 510 are without steps or inflection points, preventing the roller 410 of the chain 400 from encountering another impact after passing the chamfer.

[0138] Specifically, the connection between the inlet end 510a of the inlet arc surface 520 and the guide surface 510 satisfies second-order geometric continuity, thus enabling a smooth transition at the connection between the inlet arc surface 520 and the guide surface 510.

[0139] Among them, the imported arc surface 520 itself is a second-order continuous surface. For example, the imported arc surface 520 itself is a second-order continuous surface. In this way, the surface profile of the imported arc surface 520 has no inflection points and no curvature abrupt change. The slope (first derivative) and curvature (second derivative) are both in a smooth and gradual state, forming a smooth guide surface without hard edges and no breaks, which can eliminate contact interference when the chain 400 enters the rail.

[0140] Furthermore, the guide rail 500 has a guide arc surface 530 located at the exit end 510b away from the inlet end 510a. The guide arc surface 530 is smoothly connected to the exit end 510b of the guide surface 510. Along the running direction of the chain 400 that abuts against the guide surface 510, the guide arc surface 530 gradually approaches the fourth side portion 502. The guide arc surface 530 can provide guidance for the departure of the roller 410 of the chain 400. The guide arc surface 530 can be formed by rounding corners. The arc length of the guide arc surface 530 can be 6mm-15mm. For example, the arc length of the guide arc surface 530 can be 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm.

[0141] It is understandable that when the roller 410 of the chain 400 runs to the exit end 510b of the guide surface 510, if the exit end 510b does not have a guide arc surface 530 (such as a right angle edge) or the connection is not smooth, the roller 410 of the chain 400 will suddenly lose its constraint, resulting in the instantaneous release of tension and a pulling impact with the exit end 510b of the guide rail 500, causing severe vibration and high-frequency abnormal noise.

[0142] Specifically, the connection between the deriving arc surface 530 and the exit end 510b of the guide surface 510 satisfies second-order geometric continuity, thus achieving a smooth transition at the connection between the deriving arc surface 530 and the exit end 510b of the guide surface 510.

[0143] Among them, the derived arc surface 530 itself is a second-order continuous surface. Thus, the surface profile of the derived arc surface 530 has no inflection points and no abrupt curvature changes. The slope (first derivative) and curvature (second derivative) are both in a smooth and gradual state, forming a smooth guide surface without hard edges and no breaks, which can eliminate contact interference when the chain 400 derails.

[0144] In some embodiments, both the inlet arc surface 520 and the outlet arc surface 530 are coated with a lubricating coating, such as a PTFE or MoS2 coating, which has a low coefficient of friction and can reduce the frictional resistance between the chain 400 and the guide rail 500.

[0145] like Figure 14 As shown, in some embodiments, the guide rail 500 is provided with a second reinforcing rib 540 to improve the overall strength and reduce the risk of deformation of the guide rail 500.

[0146] This application also provides an engine including the above-described engine timing system, and more particularly including the tensioner 100 in the above-described engine timing system.

[0147] In the engine of this application, when the engine is operating in the first speed range, the oil pressure in the oil chamber 121 is lower than the opening pressure of the bypass valve 130, the bypass valve 130 remains closed, and the oil in the oil chamber 121 is discharged through the first pressure relief channel 122. The orifice diameter of the first pressure relief channel 122 can be set to meet the requirement that the oil in the oil chamber 121 forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod 120 due to tension changes in the chain 400, forcing it to respond smoothly to the vibration displacement of the chain 400. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain 400, reducing frictional work; on the other hand, the high damping characteristic makes the piston rod 120 respond more smoothly to the vibration of the chain 400, reducing the noise of the chain 400 and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), when the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the bypass valve 130 opens. The oil in the oil chamber 121 is discharged not only through the first pressure relief channel 122, but also through the second pressure relief channel 123. At this time, it is equivalent to increasing the discharge flow rate of the oil. The flow resistance of the oil in the oil chamber 121 is reduced, and the damping effect is automatically weakened. This allows the piston rod 120 to adjust its displacement more flexibly with the tension change of the chain 400, which improves the problem of energy loss caused by excessive damping when the engine is operating in the second speed range. At the same time, it can reduce the vibration risk of the chain 400 and allow the piston rod 120 to quickly adapt to the tension fluctuation of the chain 400, improving the problem of the chain 400 being too tight or too loose. Thus, by setting a first pressure relief channel 122 and a second pressure relief channel 123, and by setting a bypass valve 130 to control the opening or blocking of the second pressure relief channel 123, this application can meet the requirement that the oil in the oil chamber 121 obtains higher damping when the engine is in the first speed range, and can also meet the problem of excessive damping of the oil in the oil chamber 121 when the engine is in the second speed range.

[0148] This application also provides a vehicle including the aforementioned engine. The vehicle can be a private car, such as a sedan, SUV, MPV, or pickup truck; it can also be a commercial vehicle, such as a van or bus; and it can be a gasoline-powered vehicle or a range-extended electric vehicle.

[0149] The vehicle of this application is equipped with the aforementioned engine. When the engine is operating in the first speed range, the oil pressure in the oil chamber 121 is lower than the opening pressure of the bypass valve 130, the bypass valve 130 remains closed, and the oil in the oil chamber 121 is discharged through the first pressure relief channel 122. The orifice diameter of the first pressure relief channel 122 can be set to meet the requirement that the oil in the oil chamber 121 forms a high damping effect when the engine is operating in the first speed range. This limits the rapid extension and retraction of the piston rod 120 due to tension changes in the chain 400, forcing it to respond smoothly to the vibration displacement of the chain 400. On the one hand, this effectively suppresses the lateral sway and linear velocity pulsation of the slack side of the chain 400, reducing frictional work. On the other hand, the high damping characteristic makes the piston rod 120 respond more smoothly to the vibration of the chain 400, reducing the noise of the chain 400 and improving the NVH performance of the engine when operating in the first speed range. When the engine is operating in the second speed range (where the second speed range is greater than the first speed range), when the oil pressure in the oil chamber 121 is higher than or equal to the preset value, the bypass valve 130 opens. The oil in the oil chamber 121 is discharged not only through the first pressure relief channel 122, but also through the second pressure relief channel 123. At this time, it is equivalent to increasing the discharge flow rate of the oil. The flow resistance of the oil in the oil chamber 121 is reduced, and the damping effect is automatically weakened. This allows the piston rod 120 to adjust its displacement more flexibly with the tension change of the chain 400, which improves the problem of energy loss caused by excessive damping when the engine is operating in the second speed range. At the same time, it can reduce the vibration risk of the chain 400 and allow the piston rod 120 to quickly adapt to the tension fluctuation of the chain 400, improving the problem of the chain 400 being too tight or too loose. Thus, by setting a first pressure relief channel 122 and a second pressure relief channel 123, and by setting a bypass valve 130 to control the opening or blocking of the second pressure relief channel 123, this application can meet the requirement that the oil in the oil chamber 121 obtains higher damping when the engine is in the first speed range, and can also meet the problem of excessive damping of the oil in the oil chamber 121 when the engine is in the second speed range.

[0150] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0151] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A tensioner for use in an engine timing system, characterized in that, include: The housing has a piston chamber with an opening and an oil inlet communicating with the piston chamber; A piston rod is disposed in the piston chamber and is movable relative to the housing. The piston rod is provided with an oil chamber communicating with the oil inlet, a first pressure relief channel communicating with the oil chamber, and a second pressure relief channel communicating with the oil chamber. A bypass valve is provided at the second pressure relief channel. The bypass valve is opened when the oil pressure in the oil chamber is higher than or equal to a preset value.

2. The tensioner according to claim 1, characterized in that, The preset value is greater than or equal to 300 kPa and less than or equal to 450 kPa; and / or, the axis of the first pressure relief channel is parallel to the direction of movement of the piston rod; and / or, the axis of the second pressure relief channel is parallel to the direction of movement of the piston rod.

3. The tensioner according to claim 1, characterized in that, The first pressure relief channel includes a first pressure relief hole, which extends through the wall of the oil chamber. The diameter of the first pressure relief hole is D1, which satisfies the condition: 0.20mm≤D1≤0.25mm.

4. The tensioner according to claim 1, characterized in that, The second pressure relief channel includes a second pressure relief hole, which has an oil inlet end and an oil outlet end disposed opposite to each other, and the oil inlet end extends through the cavity wall of the oil chamber; The bypass valve includes a valve core disposed on the piston rod and a first elastic element disposed on the piston rod and acting on the valve core; When the oil pressure in the oil chamber is lower than the preset value, the valve core abuts against the piston rod under the elastic action applied by the first elastic element to close the oil outlet end. When the oil pressure in the oil chamber is higher than or equal to the preset value, the valve core moves relative to the piston rod to open the oil outlet end.

5. The tensioner according to claim 4, characterized in that, The diameter of the second pressure relief hole is D2, which satisfies: 0.45mm≤D2≤0.60 mm; And / or, the second pressure relief channel further includes a third pressure relief hole disposed in the housing and located at the end of the second pressure relief hole away from the oil cavity, the first elastic member being disposed in the third pressure relief hole and abutting against the end of the valve core away from the oil cavity, a support member being disposed on the housing, the support member being used to support the end of the first elastic member away from the valve core, and the second pressure relief channel further includes a fourth pressure relief hole disposed in the support member and communicating with the third pressure relief hole.

6. The tensioner according to claim 1, characterized in that, It also includes a second elastic element and a damping pad; The direction of motion of the piston rod when it extends is defined as the first direction, and the direction of motion when it compresses is defined as the second direction; The second elastic member includes a first abutting end and a second abutting end disposed opposite to each other, the first abutting end and the second abutting end being arranged along the first direction; The damping pad is disposed on the housing, the first abutting end abuts against the damping pad, and the second abutting end abuts against the piston rod; or, the damping pad is disposed on the piston rod, the first abutting end abuts against the housing, and the second abutting end abuts against the damping pad. The second elastic element is used to apply a force along the first direction to the piston rod.

7. The tensioner according to claim 1, characterized in that, It also includes a second elastic element and a damping pad; The direction of motion of the piston rod when it extends is defined as the first direction, and the direction of motion when it compresses is defined as the second direction; The piston rod has a first end and a second end that are arranged opposite to each other, the first end and the second end are arranged along the first direction, and the oil cavity penetrates the end face of the first end and forms an opening; The sidewall of the piston chamber is formed with a positioning step surface, and the opening is oriented toward the positioning step surface; The second elastic member includes a first abutment end and a second abutment end disposed opposite to each other, the first abutment end and the second abutment end being arranged along the first direction, the damping pad being disposed on the positioning step surface, a portion of the structure of the second elastic member passing through the oil cavity and abutting the second abutment end against the piston rod, and a portion of the structure of the second elastic member extending out of the oil cavity and abutting the first abutment end against the damping pad.

8. The tensioner according to claim 6 or 7, characterized in that, The thickness of the damping pad is greater than or equal to 0.3 mm and less than or equal to 1.0 mm, wherein the thickness direction of the damping pad is parallel to the first direction.

9. An engine timing system, characterized in that, include: Chain; The tension arm braces against the chain; The tensioner according to any one of claims 1 to 8, wherein the piston rod abuts against the side of the tensioning arm away from the chain.

10. An engine, characterized in that, Includes the engine timing system as described in claim 9.

11. A vehicle, characterized in that, Includes the engine as described in claim 10.

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