Transmission bearing structure

Abstract

To provide a transmission bearing structure capable of suppressing hydrogen embrittlement separation.SOLUTION: The transmission bearing structure includes a rotary shaft, a rolling bearing, and a housing member. The rolling bearing supports the rotary shaft. To the housing member, the rolling bearing is fixed. In the rotary shaft, an oil passing hole is provided where lubricating oil can pass therethrough. The housing member is provided with a space communicated with the oil passage hole. The transmission bearing structure is constructed so that the lubricating oil flows from the oil passing hole into the space and passes from the space into the rolling bearing, and then it is discharged. The rolling bearing includes a seal member which can suppress the flow amount of the lubricating oil passing into the rolling bearing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a bearing structure for a transmission.

Background Art

[0002] In recent years, in bearings for continuously variable transmissions (CVTs), improvement of hydrogen embrittlement peeling, which is a kind of specific peeling, has been demanded. Japanese Patent Application Laid-Open No. 2000-282178 (Patent Document 1) discloses a rolling bearing having an inner ring and an outer ring with a high chromium content. According to this rolling bearing, by forming a chromium oxide film on the raceway surface or the rolling surface, hydrogen is prevented from entering the inner ring and the outer ring, and hydrogen embrittlement peeling is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order for hydrogen to penetrate into steel, it is necessary to remove the oxide film on the steel surface and expose a fresh surface. In the atmosphere, an oxide film is instantaneously formed on the fresh surface. However, in a situation where the fresh surface is immersed in lubricating oil, the fresh surface is not exposed to air. Therefore, the formation of the oxide film on the fresh surface is suppressed. Therefore, in steel in a state where the fresh surface is exposed, the probability of hydrogen intrusion increases.

[0005] In recent years, transmissions have employed oil pumps to supply lubricating oil to rotating parts such as bearings. The flow rate of the lubricating oil increases with the rotational speed of the rotating parts. The lubricating oil passes through the inside of the bearing, is discharged, and returns to the oil tank. At high rotational speeds, the flow rate of lubricating oil supplied to the bearing is greater than the flow rate of lubricating oil discharged from the bearing. As a result, the inside of the bearing remains immersed in lubricating oil for extended periods. Consequently, the pristine surface of the bearing is exposed for long periods, making it susceptible to hydrogen intrusion into the bearing. Therefore, it has been difficult to suppress hydrogen embrittlement delamination in transmission bearing structures.

[0006] This disclosure was made to solve the above-mentioned problems and aims to provide a transmission bearing structure capable of suppressing hydrogen embrittlement delamination. [Means for solving the problem]

[0007] The transmission bearing structure according to this disclosure comprises a rotating shaft, a rolling bearing, and a housing member. The rolling bearing supports the rotating shaft. The rolling bearing is fixed to the housing member. The rotating shaft is provided with an oil passage through which lubricating oil can pass. The housing member is provided with a space communicating with the oil passage. The transmission bearing structure is configured such that lubricating oil flows from the oil passage into the space, passes through the inside of the rolling bearing, and is discharged. The rolling bearing includes a sealing member capable of suppressing the flow rate of lubricating oil passing through the inside of the rolling bearing.

[0008] In the above-described transmission bearing structure, the rolling bearing may include an inner ring and an outer ring positioned outside the inner ring. The sealing member may be in contact with both the outer ring and the inner ring.

[0009] In the above-described transmission bearing structure, the sealing member includes a first sealing portion located on the lubricating oil inflow side and a second sealing portion located on the lubricating oil outflow side. The first sealing portion may be in contact with the inner ring.

[0010] In the above-described transmission bearing structure, the interference fit of the first seal portion may be larger than the interference fit of the second seal portion.

[0011] In the above-described transmission bearing structure, the sealing member may be located only on the side where the lubricating oil flows in. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a transmission bearing structure that can suppress hydrogen embrittlement delamination. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view showing the configuration of a transmission bearing structure according to the first embodiment. [Figure 2] This is a schematic cross-sectional view along line II-II in Figure 1. [Figure 3] This is a schematic cross-sectional diagram showing the structure of a rolling bearing. [Figure 4] This is a schematic cross-sectional view showing the overlap of the seal portion. [Figure 5] This is a schematic diagram showing the relationship between seal torque and seal tightening allowance. [Figure 6] This is a schematic cross-sectional view showing the flow of lubricating oil in a transmission bearing structure according to the first embodiment. [Figure 7] This is a schematic cross-sectional view showing the flow of lubricating oil in a rolling bearing of a transmission bearing structure according to the first embodiment. [Figure 8] This is a schematic cross-sectional view showing the configuration of the rolling bearing in the transmission bearing structure according to the second embodiment. [Modes for carrying out the invention]

[0014] Embodiments of this disclosure will be described below with reference to the drawings. In the following drawings, the same or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0015] (First Embodiment) First, the configuration of the transmission bearing structure according to the first embodiment of the present disclosure will be described. FIG. 1 is a partial cross-sectional schematic view showing the configuration of the transmission bearing structure according to the first embodiment. As shown in FIG. 1, the transmission bearing structure 100 according to the first embodiment is, for example, a bearing for a continuously variable transmission (CVT), and mainly includes a rotating shaft 1, a rolling bearing 2, a housing member 70, a primary pulley 10, and a power transmission belt 4. An oil passage hole 3 is provided in the rotating shaft 1. Lubricating oil can pass through the oil passage hole 3.

[0016] The rotating shaft 1 has a third inner peripheral surface 23, a third outer peripheral surface 20, and a side end surface 24. The third outer peripheral surface 20 is located outside the third inner peripheral surface 23. The third inner peripheral surface 23 constitutes the oil passage hole 3. The oil passage hole 3 opens to the side end surface 24. The side end surface 24 is continuous with each of the third inner peripheral surface 23 and the third outer peripheral surface 20.

[0017] The third outer peripheral surface 20 may have a first outer peripheral portion 21 and a second outer peripheral portion 22. The diameter of the first outer peripheral portion 21 is larger than the diameter of the second outer peripheral portion 22. The second outer peripheral portion 22 is continuous with the side end surface 24. The primary pulley 10 is attached to the rotating shaft 1. The primary pulley 10 rotates together with the rotating shaft 1. The primary pulley 10 may be integral with the rotating shaft 1. The primary pulley 10 is in contact with the first outer peripheral portion 21.

[0018] The rolling bearing 2 supports the rotating shaft 1. The rolling bearing 2 is in contact with the second outer peripheral surface portion 22 of the rotating shaft 1. The rolling bearing 2 is fixed to the housing member 70. The rotating shaft 1 is configured to be rotatable around the central axis R. The central axis R of the rotating shaft 1 coincides with the central axis R of the rolling bearing 2. In the present disclosure, the direction along the rotating shaft 1 is defined as the axial direction X. The direction perpendicular to the axial direction X is defined as the radial direction Y. The type of the rolling bearing 2 is not particularly limited. The rolling bearing 2 may be a deep groove ball bearing, an angular ball bearing, a cylindrical roller bearing, a tapered roller bearing, or the like.

[0019] A space (first space 61) communicating with the oil passage hole 3 is provided in the housing member 70. The housing member 70 has, for example, a first member 71, a second member 72, and a third member 73. The first member 71 faces the side end surface 24 of the rotating shaft 1. The first member 71 is a plate-like member. The first member 71 intersects a straight line (central axis R) along the axial direction X.

[0020] The second member 72 is continuous with the first member 71. The second member 72 is a hollow cylindrical member. In the axial direction X, the second member 72 is located between the first member 71 and the primary pulley 10. The second member 72 is in contact with the rolling bearing 2. The second member 72 surrounds the rolling bearing 2. The third member 73 is continuous with the second member 72. In the radial direction Y, the third member 73 is located outside the second member 72. The third member 73 surrounds the second member 72.

[0021] The first space 61 is a space formed by the first member 71, the second member 72, the rolling bearing 2, and the side end surface 24 of the rotating shaft 1. In the axial direction X, the first space 61 is located on the first member 71 side with respect to the rolling bearing 2. From another perspective, in the axial direction X, the first space 61 is located between the first member 71 and the side end surface 24 of the rolling bearing 2.

[0022] The second space 62 is formed by the second member 72, the third member 73, the rolling bearing 2, the first outer peripheral surface 21 of the rotating shaft 1, and the primary pulley 10. In the axial direction X, the second space 62 is located on the primary pulley 10 side relative to the rolling bearing 2. From another perspective, in the axial direction X, the second space 62 is located between the primary pulley 10 and the rolling bearing 2.

[0023] The transmission bearing structure 100 according to the first embodiment may have a secondary pulley (not shown). The power transmission belt 4 is stretched between the primary pulley 10 and the secondary pulley. In other words, the rotational force of the primary pulley 10 is transmitted to the secondary pulley via the power transmission belt 4. The primary pulley 10 is, for example, a drive-side pulley. The secondary pulley is, for example, a driven-side pulley.

[0024] The primary pulley 10 includes a first sheave 11 and a second sheave 12. One of the first sheave 11 and the second sheave 12 may be configured to be displaceable along the axial direction X. The distance between the first sheave 11 and the second sheave 12 may change as one of the first sheave 11 and the second sheave 12 is displaced in the axial direction X.

[0025] Figure 2 is a schematic cross-sectional view along the line II-II in Figure 1. The cross-section shown in Figure 2 is perpendicular to the straight line (central axis R) along the axial direction X. As shown in Figure 2, the rolling bearing 2 has an inner ring 40, an outer ring 30, and a sealing member 50. The inner ring 40 has a first inner circumferential surface 42 and a first outer circumferential surface 41. In the radial direction Y, the first outer circumferential surface 41 is located outside the first inner circumferential surface 42. The first inner circumferential surface 42 is in contact with the third outer circumferential surface 20 of the rotating shaft 1. Specifically, the first inner circumferential surface 42 is in contact with the second outer circumferential surface portion 22 of the rotating shaft 1.

[0026] In the radial direction Y, the outer ring 30 is positioned outside the inner ring 40. The outer ring 30 has a second inner circumferential surface 31 and a second outer circumferential surface 32. In the radial direction Y, the second outer circumferential surface 32 is located outside the second inner circumferential surface 31. In the radial direction Y, the sealing member 50 is positioned between the outer ring 30 and the inner ring 40. The sealing member 50 may be in contact with each of the outer ring 30 and the inner ring 40. Specifically, the sealing member 50 may be in contact with each of the second inner circumferential surface 31 of the outer ring 30 and the first outer circumferential surface 41 of the inner ring 40.

[0027] Figure 3 is a schematic cross-sectional view showing the configuration of the rolling bearing 2. As shown in Figure 3, the rolling bearing 2 further comprises, for example, a plurality of rolling elements 5 and a cage 6. The plurality of rolling elements 5 are provided between the inner ring 40 and the outer ring 30. The cage 6 holds the plurality of rolling elements 5 so that each of the rolling elements 5 does not come into contact with the others. The cage 6 is provided between the inner ring 40 and the outer ring 30.

[0028] The sealing member 50 has, for example, a first sealing portion 50a and a second sealing portion 50b. The first sealing portion 50a is located on the lubricating oil inflow side. The second sealing portion 50b is located on the lubricating oil outflow side. Each of the first sealing portion 50a and the second sealing portion 50b has, for example, a first sealing lip 51, a second sealing lip 52, an outer end 54, a main body 53, and a core 55. Each of the first sealing lip 51, the second sealing lip 52, the outer end 54, and the main body 53 is an elastic material (for example, rubber). The core 55 is, for example, metal. The rigidity of the core 55 is greater than the rigidity of each of the first sealing lip 51, the second sealing lip 52, the outer end 54, and the main body 53.

[0029] The first seal lip 51 is, for example, a radial seal. The first seal lip 51 may also be an axial seal. The second seal lip 52 is, for example, an axial seal. The second seal lip 52 may also be a radial seal.

[0030] In the radial direction Y, the first seal lip 51 and the second seal lip 52 are located inward relative to the main body 53. In the radial direction Y, the outer end 54 is located outward relative to the main body 53. The main body 53 is in contact with the core 55. In the axial direction X, the retainer 6 is located between the first seal portion 50a and the second seal portion 50b. Similarly, in the axial direction X, each of the multiple rolling elements 5 is located between the first seal portion 50a and the second seal portion 50b.

[0031] The first outer surface 41 of the inner ring 40 has a first racing surface 44, a first recess 43, and a first end surface 45. The first racing surface 44 is the surface on which each of the multiple rolling elements 5 races. The first racing surface 44 is a concave surface. In the axial direction X, the first recess 43 is provided on both sides of the first racing surface 44. In the axial direction X, the first end surface 45 is located outside the first recess 43. From another point of view, in the axial direction X, the first recess 43 is located between the first end surface 45 and the first racing surface 44.

[0032] The second inner circumferential surface 31 of the outer ring 30 has a second rolling surface 34 and a second recess 33. The second rolling surface 34 is the surface on which each of the multiple rolling elements 5 rolls. The second rolling surface 34 is a concave surface. In the axial direction X, the second recess 33 is provided on both sides of the second rolling surface 34.

[0033] As shown in Figure 3, the first seal lip 51 may be in contact with the first end face 45. The second seal lip 52 may be located within the first recess 43. The second seal lip 52 may be in contact with the surface constituting the first recess 43. The outer end portion 54 is located within the second recess 33. The outer end portion 54 is in contact with the surface constituting the second recess 33.

[0034] Figure 4 is a schematic cross-sectional view showing the interference fit of the seal portion. The state on the left of Figure 4 shows a "negative" interference fit. The state in the center of Figure 4 shows a "positive" or "zero" interference fit. The state on the right of Figure 4 shows the natural state in which the seal portion is not deformed by external force when the interference fit is "positive". When the seal portion is pressed against the first outer peripheral surface 41 of the inner ring 40, the seal portion undergoes elastic deformation. As a result, the seal portion generates a force that tightens the first outer peripheral surface 41.

[0035] In the example shown in Figure 4, the seal portion has a sealing effect between the seal portion and the first outer peripheral surface 41 in the radial direction Y. In the radial direction Y, the interference fit is the distance between the lower end of the seal portion in its natural state and the lower end of the seal portion in its elastically deformed state. If the seal portion is tightened by the first outer peripheral surface 41, the interference fit is positive. If the seal portion is not tightened by the first outer peripheral surface 41, the interference fit is negative.

[0036] The sealing portion may also have a sealing effect between the sealing portion and the first outer peripheral surface 41 in the axial direction X. In this case, an overlap is defined in the axial direction X. In the axial direction X, the overlap T is the distance between the side edge of the sealing portion in its natural state and the side edge of the sealing portion in its elastically deformed state.

[0037] Figure 5 is a schematic diagram showing the relationship between seal torque and seal overlap. The vertical axis represents seal torque. The horizontal axis represents seal overlap. Seal torque is the drag resistance generated when the seal slides against the first outer peripheral surface 41 of the inner ring 40. When the seal is tightly compressed, the seal overlap is a positive value. Conversely, when the seal is loosely compressed, the seal overlap is a negative value.

[0038] As shown in Figure 5, the torque of the seal increases as the overlap increases. The overlap of the first seal portion 50a, located on the lubricating oil inlet side, may be greater than the overlap of the second seal portion 50b, located on the lubricating oil outlet side. The overlap of the first seal portion 50a is a positive value. The overlap of the second seal portion 50b may be a negative value, a positive value, or zero.

[0039] The overlap of the first seal lip 51 of the first seal portion 50a in the radial direction Y may be greater than the overlap of the first seal lip 51 of the second seal portion 50b in the radial direction Y. The overlap of the second seal lip 52 of the first seal portion 50a in the axial direction X may be greater than the overlap of the second seal lip 52 of the second seal portion 50b in the axial direction X.

[0040] The overlap of the first seal lip 51 of the first seal portion 50a in the radial direction Y is a positive value. The overlap of the first seal lip 51 of the second seal portion 50b in the radial direction Y may be a negative value, a positive value, or zero. The overlap of the second seal lip 52 of the first seal portion 50a in the axial direction X is a positive value. The overlap of the second seal lip 52 of the second seal portion 50b in the axial direction X may be a negative value, a positive value, or zero.

[0041] Figure 6 is a schematic cross-sectional view showing the flow of lubricating oil in the transmission bearing structure 100 according to the first embodiment. Arrow D indicates the flow of lubricating oil. The lubricating oil flows in the oil passage hole 3 of the rotating shaft 1 along the axial direction X toward the first member 71. The lubricating oil exiting the oil passage hole 3 flows into the first space 61 formed in the housing member 70. Next, the lubricating oil flows into the interior of the rolling bearing 2. The lubricating oil exiting the rolling bearing 2 is discharged into the second space 62 formed in the housing member 70. In other words, the transmission bearing structure 100 is configured such that the lubricating oil flows from the oil passage hole 3 to the first space 61, passes through the interior of the rolling bearing 2 from the first space 61, and is discharged into the second space 62.

[0042] Figure 7 is a schematic cross-sectional view showing the flow of lubricating oil in the rolling bearing 2 of the transmission bearing structure 100 according to the first embodiment. As shown in Figure 7, the lubricating oil passes through the inside of the rolling bearing 2. Specifically, the lubricating oil passes through the space between the first outer circumferential surface 41 of the inner ring 40 and the second inner circumferential surface 31 of the outer ring 30.

[0043] Most of the lubricating oil (for example, 90%) is prevented from entering the interior of the rolling bearing 2 by the first seal portion 50a. In other words, most of the lubricating oil is repelled by the first seal portion 50a (see arrow A). That is, the seal member 50 can suppress the flow rate of lubricating oil passing through the interior of the rolling bearing 2. Some of the lubricating oil (for example, 10%) passes between the first seal portion 50a and the inner ring 40 and enters the interior of the rolling bearing 2 (see arrow B). The lubricating oil passes between the second seal portion 50b and the inner ring 40 and is discharged from the interior of the rolling bearing 2 (see arrow C). Some of the lubricating oil may flow from the first space 61 to the second space 62 through the gap between the rolling bearing 2 and the housing member 70 without passing through the interior of the rolling bearing 2.

[0044] (Second Embodiment) Next, the transmission bearing structure 100 according to the second embodiment will be described. The transmission bearing structure 100 according to the second embodiment differs from the transmission bearing structure 100 according to the first embodiment mainly in that the seal member 50 is located only on the lubricating oil inflow side, while other configurations are the same as those of the transmission bearing structure 100 according to the first embodiment. The following description will focus on the configurations that differ from the transmission bearing structure 100 according to the first embodiment.

[0045] Figure 8 is a schematic cross-sectional view showing the configuration of the rolling bearing 2 of the transmission bearing structure 100 according to the second embodiment. As shown in Figure 8, the seal member 50 is located only on the lubricating oil inflow side. In other words, the seal member 50 is not located on the lubricating oil outflow side. The seal member 50 has only a first seal portion 50a. The seal member 50 does not have a second seal portion 50b.

[0046] The overlap of the first seal portion 50a may be a positive value, a negative value, or zero. Specifically, the overlap of the first seal lip 51 of the first seal portion 50a in the radial direction Y may be a positive value, a negative value, or zero. The overlap of the second seal lip 52 of the first seal portion 50a in the axial direction X may be a positive value, a negative value, or zero.

[0047] Next, the effects and advantages of the transmission bearing structure 100 according to the above embodiment will be described.

[0048] In the transmission bearing structure 100 according to this embodiment, lubricating oil is configured to flow from the oil passage hole 3 to the first space 61, and then be discharged from the first space 61 through the inside of the rolling bearing 2. The rolling bearing 2 includes a sealing member 50 that can suppress the flow rate of lubricating oil passing through the inside of the rolling bearing 2. The sealing member 50 reduces the amount of lubricating oil supplied to the inside of the rolling bearing 2. Therefore, even at high-speed rotation, it is possible to suppress the inside of the rolling bearing 2 from being immersed in lubricating oil for a long time. Consequently, after a new surface is formed due to wear of the rolling surface of the rolling bearing 2, an oxide film is rapidly formed on the new surface. As a result, it is possible to suppress the intrusion of hydrogen into the components constituting the rolling bearing 2. This makes it possible to suppress hydrogen embrittlement delamination in the transmission bearing structure 100.

[0049] In the transmission bearing structure 100 according to this embodiment, the rolling bearing 2 includes an inner ring 40 and an outer ring 30 disposed outside the inner ring 40. The sealing member 50 is in contact with the inner ring 40. This suppresses the supply of lubricating oil to the inside of the rolling bearing 2 compared to the case where the sealing member 50 is not in contact with the inner ring 40. Therefore, it is possible to suppress the intrusion of hydrogen into the outer ring 30 and the inner ring 40. As a result, hydrogen embrittlement delamination can be further suppressed.

[0050] In the transmission bearing structure 100 according to this embodiment, the sealing member 50 includes a first sealing portion 50a located on the lubricating oil inflow side and a second sealing portion 50b located on the lubricating oil outflow side. The first sealing portion 50a is in contact with the inner ring 40. This prevents lubricating oil from being supplied into the interior of the rolling bearing 2. Therefore, it is possible to prevent hydrogen from entering the outer ring 30 and the inner ring 40. As a result, hydrogen embrittlement delamination can be further suppressed.

[0051] In the transmission bearing structure 100 according to this embodiment, the overlap of the first seal portion 50a is greater than the overlap of the second seal portion 50b. This makes it possible to make the flow rate of lubricating oil discharged from inside the rolling bearing 2 greater than the flow rate of lubricating oil supplied to inside the rolling bearing 2. Therefore, an air layer can be secured inside the rolling bearing 2. As a result, an oxide film can be rapidly formed on the fresh surface of the rolling bearing 2. Consequently, hydrogen embrittlement delamination can be further suppressed.

[0052] In the transmission bearing structure 100 according to this embodiment, the seal member 50 is positioned only on the lubricating oil inflow side. This allows for an even greater flow rate of lubricating oil discharged from inside the rolling bearing 2. As a result, an air layer can be maintained inside the rolling bearing 2 for a longer period of time. Consequently, an oxide film can be formed more rapidly on the fresh surface of the rolling bearing 2. Therefore, hydrogen embrittlement delamination can be further suppressed.

[0053] While embodiments of this disclosure have been described above, various modifications of these embodiments are possible. Furthermore, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0054] 1 Rotating shaft, 2 Bearing, 3 Oil passage hole, 4 Power transmission belt, 5 Rolling element, 6 Cage, 10 Primary pulley, 11 First sheave, 12 Second sheave, 20 Third outer surface, 21 First outer surface portion, 22 Second outer surface portion, 23 Third inner surface, 24 Side end face, 30 Outer ring, 31 Second inner surface, 32 Second outer surface, 33 Second recess, 34 Second running surface, 40 Inner ring, 41 First outer surface, 42 First inner surface, 43 First recess, 44 First running surface, 45 First end face, 50 Seal member, 50a First seal portion, 50b Second seal portion, 51 First seal lip, 52 Second seal lip, 53 Main body portion, 54 Outer end portion, 55 Core portion, 61 First space, 62 Second space, 70 Housing member, 71 First member, 72 Second member, 73 Third member, 100 Transmission bearing structure, A, B, C, D Arrows, R Center axis, T Clamp, X Axial direction, Y Radial direction.

Claims

1. A rotation axis; a rolling bearing for supporting the rotating shaft; a housing member to which the rolling bearing is fixed, The rotating shaft is provided with an oil passage hole through which lubricating oil can pass, The housing member is provided with a space that communicates with the oil passage hole, the transmission bearing structure is configured so that the lubricating oil flows from the oil passage hole to the space and is discharged from the space through the inside of the rolling bearing, The rolling bearing includes a seal member capable of restricting the flow rate of the lubricating oil passing through the inside of the rolling bearing.

2. the rolling bearing includes an inner ring and an outer ring disposed outside the inner ring, The bearing structure for a transmission according to claim 1 , wherein the seal member contacts the inner ring.

3. The seal member includes a first seal portion disposed on the inflow side of the lubricating oil and a second seal portion disposed on the outflow side of the lubricating oil, The transmission bearing structure according to claim 2 , wherein the first seal portion contacts the inner ring.

4. 4. The bearing structure for a transmission according to claim 3, wherein an interference of the first seal portion is larger than an interference of the second seal portion.

5. 3. The transmission bearing structure according to claim 1, wherein the seal member is disposed only on the inflow side of the lubricating oil.

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