A vehicle wheel hub bearing assembly

Abstract

This invention relates to the field of bearing technology and discloses a vehicle wheel hub bearing assembly, including a bearing housing, an outer bearing ring, an inner bearing ring, balls, and a cage. The outer bearing ring is fixedly connected to the bearing housing. The inner wall of the outer bearing ring is provided with two inner slides, and the outer side of the inner bearing ring is provided with two outer slides. A plurality of balls are distributed along the outer side of the inner bearing ring and are located between the outer and inner slides. The cage is located outside the balls, and a sealing ring is provided between the outer and inner bearing rings. During the rotation of the inner bearing ring, the lubricating oil decreases, which leads to increased friction in the inner bearing ring and an increase in the temperature of the inner bearing ring. Under the action of heat, the sealing component automatically opens the oil outlet pipe, and under the action of centrifugal force, the feeding component can squeeze out the lubricating oil in the oil tank. Then, the lubricating oil in the oil tank can be transported from the oil outlet pipe to the oil outlet, so as to perform timely oil replenishment when the bearing lubrication fails.

Description

Technical Field

[0001] This invention relates to the field of bearing technology, specifically to a vehicle wheel hub bearing assembly. Background Technology

[0002] The wheel hub bearing assembly is a key component connecting the wheel to the car body, primarily used for load-bearing and precisely guiding the rotation of the wheel hub. It typically consists of inner and outer ring bearings, rolling elements, seals, and sensors. The inner and outer ring bearings are the core components; the inner ring connects to the axle, and the outer ring connects to the wheel hub. The rolling elements are steel balls or rollers, which reduce friction. Seals prevent external dust and moisture from entering. Sensors monitor wheel speed, providing data for systems such as ABS.

[0003] In existing vehicle bearings, the contact interface between the inner and outer raceways and the rolling elements (balls / rollers) requires lubrication to form a lubricating film, reduce the coefficient of contact friction, and inhibit wear. However, with prolonged use, wear reduces the amount of lubricating medium, leading to increased friction and abnormal temperature rise in the inner ring during rotation. This ultimately manifests as abnormal bearing noise and increased rolling resistance. Currently, traditional bearings still rely on manual, periodic grease / oil replenishment, which suffers from delayed replenishment and is prone to premature bearing failure due to lubrication failure, impacting the overall reliability of the equipment.

[0004] To address the problems mentioned above, those skilled in the art have proposed a vehicle wheel hub bearing assembly. Summary of the Invention

[0005] The purpose of this invention is to provide a vehicle wheel hub bearing assembly to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A vehicle wheel hub bearing assembly includes a bearing housing, an outer bearing ring, an inner bearing ring, balls, and a cage. The outer bearing ring is fixedly connected to the bearing housing. The inner wall of the outer bearing ring has two inner slides, and the outer wall of the inner bearing ring has two outer slides. A plurality of balls are distributed along the outer side of the inner bearing ring, and the balls are located between the outer and inner slides. The cage is disposed outside the balls. A sealing ring is provided between the outer and inner bearing rings. The assembly also includes:

[0008] Several oil storage tanks are arranged in a ring at both ends of the inner ring of the bearing and corresponding to the outer slide. An oil outlet is provided in the outer slide and the oil outlet is connected to the oil storage tank through an oil outlet pipe.

[0009] The feeding assembly is installed in the oil storage tank. During the rotation of the inner ring of the bearing with the shaft, the centrifugal force will provide extrusion pressure to the lubricating oil in the oil storage tank through the feeding assembly, so as to transport the lubricating oil in the oil storage tank to the oil outlet through the oil outlet pipe for lubricating the bearing.

[0010] A limiting component, which is disposed in the inner ring of the bearing, is used to limit the feeding component;

[0011] A sealing assembly is installed in the inner ring of the bearing and connected to the oil outlet pipe. When the bearing experiences friction due to insufficient lubrication, the inner ring of the bearing will heat up due to friction. At this time, the sealing assembly will open the oil outlet pipe due to the temperature change, thereby realizing the automatic replenishment of lubricating oil.

[0012] As a preferred embodiment of the present invention, the feeding assembly includes an extrusion plate, which is in contact with the inner wall of the oil storage tank, and a miniature counterweight is installed at one end of the extrusion plate near the axis of the inner ring of the bearing. First limiting blocks are provided on both sides of the inner wall of the oil storage tank.

[0013] As a preferred embodiment of the present invention, a sensor is installed at one end of the oil reservoir near the axis of the inner ring of the bearing.

[0014] As a preferred embodiment of the present invention, the limiting component includes a limiting groove formed on the outer side of the inner ring of the bearing and corresponding to the oil reservoir. A limiting plate is provided in the slide of the limiting groove. The limiting plate is connected to the extrusion plate through a connecting rod. The connecting rod is connected to the slide of the inner ring of the bearing. Wave grooves are formed on both sides of the limiting groove. Limiting members that cooperate with the wave grooves are provided on both sides of the limiting plate.

[0015] As a preferred embodiment of the present invention, the limiting member includes sliding cavities formed on both sides of the limiting plate, a mounting frame slidably disposed in the sliding cavity, a ball bearing disposed on the side of the mounting frame facing the wave groove, and an elastic member connected to the mounting frame disposed in the sliding cavity.

[0016] As a preferred embodiment of the present invention, the sealing assembly includes a sealing groove formed inside the inner ring of the bearing and connected to the oil outlet pipe, a sealing plate slidably disposed in the sealing groove, a communicating hole formed on the sealing plate that is offset from the oil outlet pipe, an inner cavity formed on the side of the inner ring of the bearing located on the oil outlet pipe, a sliding groove formed on the inner wall of the inner cavity, a sliding plate slidably connected to the sliding groove, two shape memory metals symmetrically distributed and connected to the sliding plate being disposed in the inner cavity, and a second limiting block being disposed in the inner cavity.

[0017] As a preferred embodiment of the present invention, the bearing inner ring has several oil replenishment pipes connected to the oil reservoir at both ends, a sealing bolt is provided at one end of the oil replenishment pipe, and a one-way valve is provided inside the oil replenishment pipe.

[0018] The present invention has the following advantages: During the rotation of the bearing inner ring, the reduction of lubricating oil will lead to increased friction in the bearing inner ring, which will cause the bearing inner ring temperature to rise. Under the action of heat, the sealing component will automatically open the oil outlet pipe, and under the action of centrifugal force, the feeding component can squeeze out the lubricating oil in the oil tank. Then, the lubricating oil in the oil storage tank can be automatically transported from the oil outlet pipe to the oil outlet. The lubricating oil squeezed out through the oil outlet can lubricate the bearing, so that when the bearing lubrication fails, the oil replenishment operation can be performed in a timely manner, avoiding the delay in oil replenishment, which will aggravate the bearing damage and reduce the bearing service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a vehicle wheel hub bearing assembly.

[0020] Figure 2 This is a cross-sectional schematic diagram of a vehicle wheel hub bearing assembly.

[0021] Figure 3 for Figure 2 A magnified view of a portion of point A in the middle.

[0022] Figure 4 This is a schematic diagram of the extrusion plate and miniature counterweight in a vehicle wheel hub bearing assembly.

[0023] Figure 5 for Figure 3 A magnified view of part B in the image.

[0024] Figure 6 This is a schematic diagram of the sealing component in a vehicle wheel hub bearing assembly.

[0025] Figure 7 for Figure 3 A magnified view of part C.

[0026] In the diagram: 1. Bearing housing; 2. Bearing outer ring; 3. Bearing inner ring; 4. Inner slide; 5. Outer slide; 6. Ball bearing; 7. Cage; 8. Sealing ring; 9. Oil reservoir; 10. First limiting block; 11. Extrusion plate; 12. Miniature counterweight; 13. Sensor; 14. Oil outlet; 15. Oil outlet pipe; 16. Sealing groove; 17. Sealing plate; 18. Connecting hole; 19. Inner cavity; 20. Slide groove; 21. Slide plate; 22. Shape memory metal; 23. Second limiting block; 24. Limiting groove; 25. Limiting plate; 26. Connecting rod; 27. Corrugated groove; 28. Slide cavity; 29. ​​Mounting bracket; 30. Ball bearing; 31. Elastic element; 32. Oil replenishment pipe; 33. One-way valve; 34. Sealing bolt; 35. Feeding assembly; 36. Limiting assembly; 37. Sealing assembly. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0028] Please see Figures 1-7 A vehicle wheel hub bearing assembly includes a bearing housing 1, an outer bearing ring 2, an inner bearing ring 3, balls 6, and a cage 7. The outer bearing ring 2 is fixedly connected to the bearing housing 1. Two inner slides 4 are provided on the inner wall of the outer bearing ring 2, and two outer slides 5 are provided on the outer side of the inner bearing ring 3. A plurality of balls 6 are distributed along the outer side of the inner bearing ring 3, and the balls 6 are located between the outer slides 5 and the inner slides 4. The cage 7 is disposed on the outer side of the balls 6. A sealing ring 8 is provided between the outer bearing ring 2 and the inner bearing ring 3. The assembly also includes:

[0029] Several oil storage grooves 9 are arranged in a ring at both ends of the inner ring 3 of the bearing and corresponding to the outer slide rail 5. An oil outlet 14 is provided in the outer slide rail 5. The oil outlet 14 is connected to the oil storage groove 9 through an oil outlet pipe 15. There are multiple oil outlet pipes 15, all located in the middle of the outer slide rail 5. The multiple oil outlet pipes 15 are spaced apart and are all connected to the oil storage groove 9. At the same time, there are also multiple oil outlets 14, which are respectively connected to several oil outlet pipes 15. This allows the lubricating oil squeezed out of the oil outlet 14 to cover the outer slide rail 5 of the inner ring 3 of the bearing more quickly.

[0030] The feeding assembly 35 is installed in the oil storage tank 9. During the rotation of the inner ring 3 of the bearing with the shaft, the centrifugal force will provide extrusion pressure on the lubricating oil in the oil storage tank 9 through the feeding assembly 35, so as to transport the lubricating oil in the oil storage tank 9 to the oil outlet 14 through the oil outlet pipe 15 for lubricating the bearing.

[0031] A limiting component 36 is disposed in the inner ring 3 of the bearing and is used to limit the feeding component 35.

[0032] The sealing component 37 is disposed in the inner ring 3 of the bearing and connected to the oil outlet pipe 15. When the bearing experiences friction due to insufficient lubrication, the inner ring 3 of the bearing will heat up due to friction. At this time, the sealing component 37 will open the oil outlet pipe 15 due to the temperature change, thereby realizing the automatic replenishment of lubricating oil.

[0033] In one instance of this embodiment, please refer to Figures 2-4 The feeding assembly 35 includes an extrusion plate 11, which is in contact with the inner wall of the oil storage tank 9. A miniature counterweight 12 is installed at one end of the extrusion plate 11 near the axis of the inner ring 3 of the bearing. First limiting blocks 10 are provided on both sides of the inner wall of the oil storage tank 9.

[0034] During the bearing processing, lubricating oil is injected into the oil reservoir 9 to fill the storage space of the oil reservoir 9, thereby providing raw materials for subsequent bearing oil replenishment. At this time, the extrusion plate 11 is located at the first limiting block 10, and the miniature counterweight 12 installed on the extrusion plate 11 can increase the centrifugal force on the extrusion plate 11 during the rotation of the inner ring 3 of the bearing, thereby generating a stronger centrifugal thrust, which facilitates the extrusion of the lubricating oil in the oil reservoir 9 from the oil outlet 14.

[0035] During the oil replenishment process, the centrifugal force generated by the rotation of the inner ring 3 of the bearing by the extrusion plate 11 will exert a squeezing force on the lubricating oil in the oil storage tank 9. Due to the blockage of the oil outlet pipe 15 by the sealing component 37, the lubricating oil will not be squeezed out. When the bearing lubricating oil is insufficient due to friction, the inner ring 3 of the bearing will rotate and the friction will increase the temperature, causing the sealing component 37 to open the oil outlet pipe 15. Driven by centrifugal force, the extrusion plate 11 will squeeze the lubricating oil in the oil storage tank 9 outward and deliver it to the oil outlet 14 through the oil outlet pipe 15. The lubricating oil squeezed out through the oil outlet 14 can directly lubricate the outer slide 5 of the inner ring 3 of the bearing. The rolling ball 6 will also be lubricated by the lubricating oil squeezed out of the oil outlet 14. Under the action of centrifugal force, the lubricating oil squeezed out of the oil outlet 14 will also be thrown onto the inner slide 4 of the outer ring 2 of the bearing. As the ball 6 rolls, the lubricating oil completely covers the inner slide 4 and the outer slide 5, thus completing the lubricating oil replenishment.

[0036] In one instance of this embodiment, please refer to Figures 2-3 A sensor 13 is installed at one end of the oil reservoir 9 near the axis of the inner ring 3 of the bearing.

[0037] Sensor 13 is used to detect the amount of lubricating oil in oil reservoir 9 and transmit the data to the vehicle computer, so that maintenance personnel can replenish the lubricating oil in oil reservoir 9 according to the data transmitted by sensor 13.

[0038] In this embodiment, sensor 13 is a distance sensor used to detect the position of the extrusion plate 11 in the oil storage tank 9, thereby determining the amount of lubricating oil in the oil storage tank 9.

[0039] In one instance of this embodiment, please refer to Figure 3 , Figure 6 and Figure 7 The limiting component 36 includes a limiting groove 24 opened on the outside of the bearing inner ring 3 and corresponding to the oil reservoir 9. A limiting plate 25 is provided in the limiting groove 24. The limiting plate 25 is connected to the extrusion plate 11 through a connecting rod 26. The connecting rod 26 is slidably connected to the bearing inner ring 3. Wave grooves 27 are opened on both sides of the limiting groove 24. Limiting members that cooperate with the wave grooves 27 are provided on both sides of the limiting plate 25.

[0040] Furthermore, the limiting member includes sliding cavities 28 formed on both sides of the limiting plate 25, a mounting bracket 29 is slidably disposed in the sliding cavity 28, a ball bearing 30 is disposed on the side of the mounting bracket 29 facing the wave groove 27, and an elastic member 31 connected to the mounting bracket 29 is disposed in the sliding cavity 28.

[0041] In the initial state, under the elastic force of the elastic element 31, the mounting bracket 29 is subjected to the elastic force on the side away from the middle of the limiting plate 25, so that the ball 30 on the mounting bracket 29 can always be in contact with the wave groove 27. By letting the ball 30 be stuck in the groove of the wave groove 27, the limiting plate 25 can be limited. The extrusion plate 11 can be limited by the connecting rod 26. When the limiting plate 25 does not have enough thrust, the ball 30 will not move along the wave groove 27. In this way, the extrusion plate 11 can be positioned when the bearing is not in working state, and the extrusion plate 11 is prevented from shaking randomly in the oil reservoir 9. Therefore, without sufficient centrifugal force, the extrusion plate 11 will not move.

[0042] When the extrusion plate 11 exerts a squeezing driving force on the lubricating oil in the oil storage tank 9 due to centrifugal force, the presence of this centrifugal force will push the limiting plate 25 to slide in the limiting groove 24 through the connecting rod 26. Due to the generation of centrifugal force, the groove of the wave groove 27 will overcome the limitation of the ball 30, so that the limiting plate 25 can slide along the limiting groove 24, and the ball 30 will roll along the wave groove 27.

[0043] In this embodiment, the specific structure of the elastic element 31 is not limited. Preferably, the elastic element 31 is set as a spring.

[0044] In one instance of this embodiment, please refer to Figure 2 , Figure 3 , Figure 5 and Figure 6 The sealing assembly 37 includes a sealing groove 16 formed in the inner ring 3 of the bearing and connected to the oil outlet pipe 15. A sealing plate 17 is slidably arranged in the sealing groove 16. A connecting hole 18 is formed on the sealing plate 17 and is offset from the oil outlet pipe 15. An inner cavity 19 is formed on one side of the inner ring 3 of the bearing located on the oil outlet pipe 15. A sliding groove 20 is formed on the inner wall of the inner cavity 19. The sliding groove 20 is slidably connected to the sliding plate 21. Two shape memory metals 22 are symmetrically distributed in the inner cavity 19 and connected to the sliding plate 21. A second limiting block 23 is formed in the inner cavity 19.

[0045] The shape memory metal 22 is initially bent. When the shape memory metal 22 reaches a certain temperature, it will unfold and the bending degree will decrease. The bending deformation of the shape memory metal 22 will push the sealing plate 17 to move in the sealing groove 16, so that the connecting hole 18 on the sealing plate 17 is misaligned or connected with the oil outlet pipe 15. Initially, the sliding plate 21 is located at the second limiting block 23. At this time, the sealing plate 17 blocks the oil outlet pipe 15. When the shape memory metal 22 unfolds, the sealing plate 17 moves to the end of the sealing groove 16 and the connecting hole 18 connects with the oil outlet pipe 15.

[0046] Specifically, when insufficient lubrication causes increased friction in the inner ring 3 of the bearing, the inner ring 3 will heat up due to friction. When the heat reaches the deformation requirement of the shape memory metal 22, the shape memory metal 22 begins to deform and pushes the slide plate 21 along the slide groove 20, thereby pushing the sealing plate 17 along the sealing groove 16 until it reaches the end of the sealing groove 16. At this time, the connecting hole 18 is connected to the oil outlet pipe 15. Under the pressure of the feeding component 35 on the lubricating oil in the oil storage tank 9, the lubricating oil will be squeezed out from the oil outlet 14 through the oil outlet pipe 15, thereby realizing the replenishment of lubricating oil.

[0047] In one instance of this embodiment, please refer to Figures 2-3 The bearing inner ring 3 has several oil replenishment pipes 32 connected to the oil reservoir 9 at both ends. A sealing bolt 34 is provided at one end of the oil replenishment pipe 32, and a one-way valve 33 is provided inside the oil replenishment pipe 32 to prevent the lubricating oil in the oil reservoir 9 from flowing out of the oil replenishment pipe 32.

[0048] When replenishing the lubricating oil, open the sealing bolt 34 and insert the external lubricating oil supply pipe into the oil supply pipe 32. The lubricating oil is then sent into the oil supply pipe 32 through the external lubricating oil supply pipe and into the oil reservoir 9 until the oil reservoir 9 is full. After that, pull out the external lubricating oil supply pipe and screw the sealing bolt 34 into the opening of the oil supply pipe 32 to seal the end of the oil supply pipe 32.

[0049] During the operation of the bearing, when the lubricating oil in the bearing decreases due to long-term wear, the friction of the inner ring 3 of the bearing intensifies during rotation. This friction causes the temperature of the inner ring 3 of the bearing to rise, causing the shape memory metal 22 of the sealing component 37 to deform under the action of heat. This drives the sealing component 37, causing it to open the oil outlet pipe 15. Due to the rotation of the inner ring 3 of the bearing, the feeding component 35 is driven by centrifugal force on the side away from the bearing rotation axis. This centrifugal force pushes the feeding component 35, allowing it to squeeze the lubricating oil in the oil storage tank 9 and deliver the lubricating oil to the oil outlet 14 through the oil outlet pipe 15.

[0050] The lubricating oil squeezed out from the oil outlet 14 enters the outer slide 5 of the inner ring 3 of the bearing, thus lubricating the outer slide 5. The rolling balls 6 also come into contact with the lubricating oil squeezed out from the oil outlet 14, thereby completing the lubrication. Under the action of centrifugal force, the lubricating oil squeezed out from the oil outlet 14 is also thrown onto the inner slide 4 of the outer ring 2 of the bearing. As the balls 6 roll, the lubricating oil completely covers the inner slide 4 and the outer slide 5, thus completing the lubricating oil replenishment of the bearing. With the replenishment of lubricating oil, the inner ring 3 of the bearing no longer generates heat due to friction, allowing the inner ring 3 of the bearing to cool down rapidly. The shape memory metal 22 will also reset due to the temperature drop, and the sealing component 37 will also reset and re-seal the oil outlet pipe 15, thus completing the automatic replenishment of lubricating oil.

[0051] The power supply and control of the electrical equipment in this application are all existing technologies and will not be elaborated upon here. The control of each component can be achieved using a PLC controller disclosed in the prior art, and the model and circuit connection of each component are not specifically limited. All electrical equipment involved are existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The scope of protection of this invention does not involve improvements to the software and methods.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A vehicle wheel hub bearing assembly, comprising a bearing housing, an outer bearing ring, an inner bearing ring, balls, and a cage, wherein the outer bearing ring is fixedly connected to the bearing housing, the inner wall of the outer bearing ring is provided with two inner slides, the outer bearing ring is provided with two outer slides, a plurality of balls are distributed along the outer side of the inner bearing ring and the balls are located between the outer slides and the inner slides, the cage is disposed outside the balls, and a sealing ring is provided between the outer bearing ring and the inner bearing ring, characterized in that, Also includes: Several oil storage tanks are arranged in a ring at both ends of the inner ring of the bearing and corresponding to the outer slide. An oil outlet is provided in the outer slide and the oil outlet is connected to the oil storage tank through an oil outlet pipe. The feeding assembly is installed in the oil storage tank. During the rotation of the inner ring of the bearing with the shaft, the centrifugal force will provide extrusion pressure to the lubricating oil in the oil storage tank through the feeding assembly, so as to transport the lubricating oil in the oil storage tank to the oil outlet through the oil outlet pipe for lubricating the bearing. A limiting component, which is disposed in the inner ring of the bearing, is used to limit the feeding component; A sealing assembly is installed in the inner ring of the bearing and connected to the oil outlet pipe. When the bearing experiences friction due to insufficient lubrication, the inner ring of the bearing will heat up due to friction. At this time, the sealing assembly will open the oil outlet pipe due to the temperature change, thereby realizing the automatic replenishment of lubricating oil. The sealing assembly includes a sealing groove formed inside the inner ring of the bearing and connected to the oil outlet pipe. A sealing plate is slidably disposed in the sealing groove. The sealing plate has a communicating hole that is offset from the oil outlet pipe. The inner ring of the bearing has an inner cavity on one side of the oil outlet pipe. A sliding groove is formed on the inner wall of the inner cavity. The sliding groove is slidably connected to a sliding plate. Two shape memory metals are symmetrically distributed inside the inner cavity and connected to the sliding plate. A second limiting block is provided inside the inner cavity.

2. The vehicle wheel hub bearing assembly according to claim 1, characterized in that, The feeding assembly includes an extrusion plate that fits against the inner wall of the oil storage tank. A miniature counterweight is installed at one end of the extrusion plate near the axis of the inner ring of the bearing. First limiting blocks are provided on both sides of the inner wall of the oil storage tank.

3. The vehicle wheel hub bearing assembly according to claim 2, characterized in that, A sensor is installed at one end of the oil reservoir near the axis of the inner ring of the bearing.

4. The vehicle wheel hub bearing assembly according to claim 2, characterized in that, The limiting component includes a limiting groove formed on the outer side of the bearing inner ring and corresponding to the oil reservoir. A limiting plate is provided in the slide of the limiting groove. The limiting plate is connected to the extrusion plate through a connecting rod. The connecting rod is connected to the slide of the bearing inner ring. Wave grooves are formed on both sides of the limiting groove. Limiting components that cooperate with the wave grooves are provided on both sides of the limiting plate.

5. The vehicle wheel hub bearing assembly according to claim 4, characterized in that, The limiting component includes sliding cavities on both sides of the limiting plate, a mounting frame is slidably arranged in the sliding cavity, a ball is arranged on the side of the mounting frame facing the wave groove, and an elastic element connected to the mounting frame is arranged in the sliding cavity.

6. The vehicle wheel hub bearing assembly according to claim 1, characterized in that, The bearing inner ring has several oil supply pipes at both ends that are connected to the oil reservoir. A sealing bolt is installed at one end of the oil supply pipe, and a one-way valve is installed inside the oil supply pipe.

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