TRUNK BEARING WITH WEAR REDUCTION SLOTS ON ONE END FACE

Abstract

Slots are provided in the end faces of the bearings in a transition region. The slots improve the balance of hydrostatic and hydrodynamic forces between the bearing and a gear mounted on a journal supported by the bearing, thus increasing the film thickness and providing greater strength at smaller clearances. The slots reduce wear on the end face resulting from the operation of the gear pump under higher pressure conditions. (Shortcut figure: Fig. 5)

Description

Title of the invention: TRUNK BEARING WITH WEAR REDUCTION SLOTS ON ONE END FACE REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority over the Indian provisional patent application, serial number 202411075034, entitled TRUNK BEARING HAVING WEAR REDUCTION SLOTS ON ONE END FACE, filed on October 4, 2024. Technological background

[0002] Fuel pumps may have different stages, including a gear stage. Trunnion bearings are provided along one or more gear trains of the gear stage. The trunnion bearings radially support the gear trains within an outer housing. The trunnion bearings also axially support the gears of the gear trains within the outer housing and provide at least some sealing against fluid leakage at the gears. To provide this sealing, a first axial force is applied to certain movable parts of the trunnion bearings to press the trunnion bearings toward the gears relative to the outer housing. This pressure may cause increased wear on the faces of the trunnion bearings facing the gears. Summary

[0003] One objective is to provide an improved concept for gear stages.

[0004] Certain aspects of the disclosure relate to one or more trunnion bearings for a gear stage of a pump (e.g., a fuel pump). The trunnion bearings support a trunnion that drives the rotation of a gear in the gear stage. The trunnion bearings have end faces facing the gear in the gear stage. The end faces include a transition region between an inlet and a discharge arc with respect to the rotation of the gears. The end faces include a plurality of slots provided in the transition region. The slots provide improved film thickness and pressure balance on the end face.Improvements to film thickness and pressure balance can increase the force at the transition region separating the gear from the bearing, especially when clearances between the gear and the bearing become smaller, thereby reducing wear occurring at the face. bearing end damage as a result of operations, particularly under high pressure conditions.

[0005] In one embodiment, a gear stage for a pump includes a housing defining a gear chamber. The housing further defines an inlet and an outlet in fluidic communication with the gear chamber. The gear stage further includes a gear arrangement located inside the gear chamber, configured to drive fluid from the inlet to the outlet. The gear arrangement includes at least one gear capable of rotating about an axis of rotation. The gear stage also includes a trunnion coupled to the gear, the trunnion extending along the axis of rotation and configured to drive rotation of the gear about the axis of rotation.The gear arrangement further includes a fixed bearing on one axial side of the gear to radially support the journal relative to the housing, allowing the journal to rotate about its axis of rotation relative to the housing, and an axially movable bearing on the opposite axial side of the gear to radially support the journal relative to the housing, allowing the journal to rotate about its axis of rotation relative to the housing. The axially movable bearing defines a through bore to receive the journal. The axially movable bearing is axially movable along the axis of rotation within the journal, toward and away from the gear. The axially movable bearing is rotationally fixed relative to the housing.At least one of the fixed bearings and the axially movable bearing includes an end face comprising a transition region between an inlet region of said bearing and a discharge arc of said bearing, the end face of said bearing including a plurality of slots formed in the transition region.

[0006] In one embodiment, a bearing for a gear stage of a pump includes a body defining a through bore extending along a longitudinal axis between a first axial end and a second axial end, the second axial end including an end face. The end face is configured to face a gear of the pump's gear stage. The end face includes a transition region between an inlet region of said bearing and a discharge arc of the bearing. The end face of the bearing includes a plurality of slots formed in the transition region.

[0007] A variety of additional inventive aspects will be set forth in the following description. The inventive aspects may relate to individual features and combinations of features. It should be understood that the preceding general description and the detailed description that follows are merely examples and explanations and are not exhaustive of the general inventive concepts on which the embodiments disclosed herein are based. Brief description of the drawings

[0008] The accompanying drawings, which are incorporated into and form part of the description, illustrate several aspects of this disclosure. A brief description of the drawings is as follows:

[0009] [Fig.1] is a perspective view of an example fuel pump including a gear stage in accordance with the principles of this disclosure;

[0010] [Fig.2] is a longitudinal cross-section of the fuel pump of [Fig.1];

[0011] [Fig.3] is a cross-section of the gear stage of the fuel pump of [Fig.1];

[0012] [Fig.4] shows components of the gear stage blown outwards from an outer housing of the fuel pump of [Fig.1];

[0013] [Fig.5] is a longitudinal section of the gear stage of the fuel pump of [Fig.1] including first and second gear trains, each gear train including a gear, a fixed bearing and a moving bearing;

[0014] [Fig.6] illustrates a movable bearing as an example to be used in a first gear train of the fuel pump of [Fig.1], the movable bearing of the second gear train being a mirror image;

[0015] [Fig.7] illustrates a fixed bearing as an example to be used in a first gear train of the fuel pump of [Fig.1], the moving bearing of the second gear train being a mirror image;

[0016] [Fig.8] illustrates an end face as an example of a bearing;

[0017] [Fig.9] illustrates an end face as an example of a bearing;

[0018] Fig. 10 illustrates another end face as an example of a bearing. Detailed description

[0019] We will now refer in detail to exemplary aspects of this disclosure which are illustrated in the accompanying drawings. Where possible, the same numerical references will be used throughout the drawings to designate identical or similar parts.

[0020] Figure 1 illustrates a fuel pump 100 for use with an engine. The fuel pump 100 conveys a fluid (for example, fuel) from an inlet 102 to an outlet 104 with one or more stages. For example, referring to Figures 2 and 3, the pump 100 includes a gear stage 106 having an outer housing 116 defining a gear chamber 118. The inlet 102 leads to an inlet region of the gear chamber 118; the outlet 104 leads to a discharge region 112 of the gear chamber 118. A gear arrangement 108 is arranged inside the gear chamber 118 and drives fluid from the inlet region 110 to the discharge region 112.

[0021] As shown in Figures 4 and 5, the gear chamber 118 extends along a longitudinal axis L. The gear arrangement 108 is located inside the gear chamber 118. The gear arrangement 108 includes a first gear train comprising a trunnion 120 extending axially inside the gear chamber 118 along the longitudinal axis L. A gear 114 of the first gear train is rotatably mounted on the trunnion 120. First and second bearings 122, 124 are mounted on the trunnion 120 at opposite sides of the gear 114 to radially support the trunnion 120 relative to the housing 116 so that the trunnion 120 can rotate about the longitudinal axis L relative to the housing 116. first and second bearings 122, 124 are fixed in rotation relative to each other and to the outer casing 116.An end cap 126 is mounted on the housing 116 to close the gear chamber 118.

[0022] In some embodiments, the components are formed from different materials. For example, the gears 114a, 114b may be made of a different metal than the movable bearings 124a, 124b and / or the housing 116. Consequently, thermal variations have different effects on the components. To compensate, the second bearings 124a, 124b are axially movable along the journal to accommodate thermal expansion and contraction during the operation of the pump 100. The first bearing 122 is both axially fixed and rotatable relative to the journal 120.

[0023] In certain embodiments, the gear arrangement 108 includes two gear trains arranged in parallel inside the gear chamber 118. Each of the first gear trains includes a respective gear 114a, 114b, a respective journal 120a, 120b extending along a respective longitudinal axis, a respective fixed bearing 122a, 122b, and a respective movable bearing 124a, 124b of the gear arrangement 108. The gear chamber 118 is formed to receive the two gear trains. In the illustrated example, the gear chamber 118 has a peanut-shaped cross-section. The gear trains are arranged close enough to each other so that at least the second bearings 124a, 124b are in contact with each other, as will be described in more detail here. As shown in [Fig.3], the first and second gears 114a, 114b mesh at a region aligned with the inlet region 110 and the discharge region 112. The teeth of the gears 114a, 114b draw fluid from the inlet region 110, along a flow path F extending between the gear teeth and the cavity 118, towards the discharge region 112. .

[0024] While a majority of the fluid is drawn towards the outlet 104 through the discharge region 112, at least some of the fluid leaks along the gear chamber 118 (for example, towards the movable bearings 124a, 124b). The fluid leaking from the inlet region 110 has a first pressure. The fluid leaking from the discharge region 112 has a second pressure that is higher than the first pressure. To reduce leakage, the movable bearings 124a, 124b are stressed against the respective gears 114a, 114b. Consequently, each gear 114a, 114b is clamped between the fixed bearing 122a, 122b and the movable bearing 124a, 124b by means of the stress force applied to the movable bearing 124a, 124b.

[0025] Figure 6 shows a first movable bearing 124a; the second movable bearing 124b of the pump 100 can be a mirror image of the first movable bearing 124a. As shown in Figure 6, each movable bearing 124a, 124b defines a through bore 132 to receive the respective journal 120a, 120b. The through bore 132 extends between a first axial end 128 and a second axial end 130 of the axially movable bearing 124a, 124b. The first axial end 128 is oriented towards the axial side of the respective gear 114a, 114b, and the second axial end 130 is oriented towards the opposite side of the respective gear 114a, 114b. Each movable bearing 124a, 124b defines flat surfaces 134 oriented transversely with respect to the longitudinal axis L.The flat surfaces 134 are configured to mesh with each other when the movable bearings 124a, 124b are mounted on the respective journals 120a, 120b inside the gear chamber 118. The meshing of the flat surfaces 134 prevents the movable bearings 124a, 124b from rotating around the journals 120a, 120b. The input region 110 is located on one side of the flat surfaces 134 and the discharge region 112 is located on the opposite side of the flat surfaces 134.

[0026] Each movable bearing 124a, 124b defines an external channel 136 extending circumferentially around a section of the outer circumferential portion at the first axial end 128. The external channel 136 has a first end 137 in fluid pressure communication with the discharge region 112. The external channel 136 extends circumferentially around the movable bearing 124a, 124b from the first end 137 to a second opposite end 138 which terminates before reaching the flat surface 134. Consequently, the external channel 136 provides a discharge fluid pressure along the section of the outer circumferential portion at the first axial end 128.

[0027] Each movable bearing 124a, 124b includes an end face 140 at the first axial end 128. The respective end faces 140 of the movable bearings 124a, 124b may be mirror images of each other. The end face 140 includes a relieving arc 144 extending circumferentially along the length of the outer channel 136. The end face 140 includes a transition region 142 extending circumferentially along the end face 140 between the inlet region 110 and the second end 138 of the outer channel 136, and radially from an inner perimeter of the end face 140 to an outer perimeter thereof. The transition region 142 is a region of the pump 100 where the fluid pressure is increased from an inlet pressure to a discharge pressure. The transition region 142 may have an angular width of more than twice the angular width of the tooth-to-tooth spacing of a corresponding gear 114a, 114b. In one embodiment, the transition region 142 has an angular width in the range of 2 to 2.5 times the angular width of the gear tooth-to-tooth spacing.

[0028] Slots 146 may be provided in the transition region 142 of the end face 140. The slots 146 may allow sufficient width and depth to permit fluidic communication. In one embodiment, slots 146 are provided entirely within the perimeter of the end face 140. In one embodiment, the slots do not extend towards the bore 132 or towards an external surface of the movable bearing 124a, 124b between the first axial end 128 and the second axial end 130. In one embodiment, the slots 146 may be provided entirely within the transition region 142 of the end face 140. In one embodiment, the slots 146 are positioned on the end face 140 such that the slots 146 are provided radially outwards from the roots of the teeth of the respective gear 114a, 114b when the respective journal 120a, 120b thereof is received in the bore 132.In one embodiment, the slots 146 may each extend radially outwards from the longitudinal axis L. In one embodiment, the slots 146 may extend in a direction inclined with respect to a radial direction extending from the longitudinal axis L. In one embodiment, at least some of the slots 146 extend circumferentially with respect to the longitudinal axis L. In one embodiment, the slots 146 extending in the circumferential direction connect one or more slots 146 extending radially outwards from the longitudinal axis L and / or one or more slots 146 extending in a direction inclined with respect to a radial direction extending from the longitudinal axis L.In one embodiment, one or more slots 146 can be positioned in a part of the transition region 142 sealed from the inlet region 110 by one or more teeth of the gear 114 during the operation of the pump 100. The one or more slots 146 can be positioned spaced from the inlet region 110 of the movable bearing 124a. 124b of at least an angular width of a tooth-to-tooth spacing of the respective gear 114a, 114b.

[0029] A groove 148 may be provided in the end face 140. The groove 148 may extend along the end face circumferentially with respect to the longitudinal axis L as far as the discharge region 112. The groove 148 may extend along a length of the discharge arc 144. In one embodiment, the groove 148 terminates at an end 150 inside the discharge arc 144. In one embodiment, the groove 148 may connect to one or more of the slots 146. In one embodiment, the groove 148 and the slots 146 are separated on the end face 140. In some examples, the groove 148 extends along the same section as the outer channel 136 so that the end 150 of the groove 148 is offset radially inward. relative to the second end 138 of the outer channel 136.In some embodiments, the groove 148 is arranged in line with the roots of the teeth of the respective gear 114a, 114b so that the fluid pressure under the teeth of the gear 114a, 114b is relatively constant (e.g., at discharge pressure).

[0030] Figure 7 shows a first fixed bearing 122a; the second fixed bearing 122b of the Pump 100 can be a mirror image of the first fixed bearing 122a. As shown in [Fig. 7], each fixed bearing 122a, 122b defines a through bore 164 to receive another part of the respective journal 120a, 120b. The through bore 164 extends between a first axial end 160 and a second axial end 162 of the fixed bearing 122a, 122b. The first axial end 160 is oriented towards the axial side of the respective gear 114a, 114b, and the second axial end 162 is oriented towards the opposite side of the respective gear 114a, 114b. Each fixed bearing 122a, 122b defines flat surfaces 166 oriented transversely towards the longitudinal axis L. The flat surfaces 166 are configured to mesh with each other when the fixed bearings 122a, 122b are mounted on the respective trunnions 120a, 120b inside the gear chamber 118.The engagement of the flat surfaces 166 inhibits rotation of the fixed bearings 122a, 122b around the trunnions 120a, 120b. The inlet region 110 is located on one side of the flat surfaces 166 and the discharge region 112 is located on the opposite side of the flat surfaces 166.

[0031] Each fixed bearing 122a, 122b defines an external channel 168 extending circumferentially around a section of the outer circumferential portion at the first axial end 160. The external channel 168 has a first end 169 in fluid pressure communication with the discharge region 112. The external channel 168 extends circumferentially around the fixed bearing 122a, 122b from the first end 169 to a second opposite end 170 which terminates before reaching the flat surface 166. Consequently, the channel external 168 provides a discharge fluid pressure along the section of the outer circumferential part at the level of the first axial end 160.

[0032] Each fixed bearing 122a, 122b includes an end face 172 at the first axial end 160. The respective end faces 172 of the movable bearings 122a, 122b may be mirror images of each other. The end face 172 includes a relief arc 176 extending circumferentially along the length of the outer channel 168. The end face 172 includes a transition region 174 extending circumferentially along the end face 172 between the inlet region 110 and the second end 170 of the outer channel 168, and radially from an inner perimeter of the end face 172 to an outer perimeter thereof. The transition region 174 is a region of the pump 100 where a fluid pressure is increased from an inlet pressure to a discharge pressure.The transition region 174 may have an angular width of more than twice the angular width of a tooth-to-tooth spacing of a corresponding gear 114a, 114b. In one embodiment, the transition region 174 has an angular width in the range of 2 to 2.5 times the angular width of a tooth-to-tooth spacing of the gear.

[0033] Slots 178 may be provided in the transition region 174 of the end face 172. The slots 178 may allow sufficient width and depth to permit fluidic communication. In one embodiment, slots 178 are provided entirely within the perimeter of the end face 172. In one embodiment, the slots do not extend towards the bore 164 or towards an external surface of the movable bearing 122a, 122b between the first axial end 160 and the second axial end 162. In one embodiment, the slots 178 may be provided entirely within the transition region 174 of the end face 172. In one embodiment, the slots 178 are positioned on the end face 172 such that the slots 178 are provided radially outwards from the roots of the teeth of the respective gear 114a, 114b when the respective journal 120a, 120b thereof is received in the bore 164.In one embodiment, the slots 178 can each extend in a radially outward direction with respect to the longitudinal axis L. In one embodiment, the slots 178 can extend in a direction inclined with respect to a radial direction extending from the longitudinal axis L. In one embodiment, at least some of the slots 178 extend in a circumferential direction with respect to the longitudinal axis L. In one embodiment, the slots 178 extending in the circumferential direction connect one or more slots 178 extending radially outward with respect to the longitudinal axis L and / or one or more slots 178 extending in a direction inclined with respect to a radial direction. extending from the longitudinal axis L. In one embodiment, one or more slots 178 can be positioned in a part of the transition region 174 sealed from the inlet region 110 by one or more teeth of the gear 114 during the operation of the pump 100. The one or more slots 178 can be positioned spaced from the inlet region 110 of the fixed bearing 122a, 122b by at least an angular width of a tooth-to-tooth spacing of the respective gear 114a, 114b.

[0034] Figure 8 illustrates an end face as an example of a bearing and a gear. corresponding to use in one of the first and second gear trains, the end face of another such bearing being a mirror image. The end face 200 or a mirror image thereof may be provided at the level of a face of fixed bearings 122a, 122b oriented towards the respective gears 114a, 114b, and / or at the level of a face of movable bearings 124a, 124b oriented towards the respective gears 114a, 114b. The gear 210 is shown superimposed on the end face 200. The gear 210 may be, for example, one of the gears 114a, 114b as described above and shown in Figures 2 to 5. The gear 210 includes teeth 212 extending from roots 214.

[0035] The end face 200 includes an inlet region 202, a transition region 204, and a discharge arc 206. The inlet region 202 is defined by the inlet, such as the inlet region 110 described above and shown in Figures 3, 6, and 7. The discharge arc 206 is a region of the end face 200 exposed to a discharge fluid pressure through an external channel 208 formed in a portion of the bearing including the end face 200. The external channel 208 extends from the end 209 to a discharge region of the bearing including the end face 200. The transition region 204 is a region between the inlet region 202 and the discharge arc 206 where the fluid pressure is increased from an inlet pressure to a discharge pressure.The transition region 204 may be above an area of ​​the end face 200 from which the teeth 212 begin to seal a chamber from the inlet region as the gear 210 rotates until the teeth 212 no longer seal the chamber due to the passage over the end 209 of the outer channel 208.

[0036] Slots 216a and 216b are provided in the transition region 204 on the end face 200. Slots 216a and 216b have sufficient width and depth to allow fluidic communication. In one embodiment, slots 216a and 216b are provided entirely within the perimeter of the end face 200. In another embodiment, slots 216a and 216b may be provided entirely within the transition region 204 of the end face 200. Each slot 216a extends radially opposite the axis of rotation of the gear 210. The slots 216b each extend circumferentially over at least a portion of the transition region 204. In one embodiment, one of the innermost slots 216b may be positioned radially outward from the roots 214 of the gear 210. The slots 216b may connect two or more of the slots 216a. In one embodiment, one or more of the slots 216b may extend over an angular width of the teeth 212 of the gear 210, thus allowing one or more of the teeth 212 to be bypassed via the slot 216b. At least some of the slots 216a, 216b can be positioned to be intermittently exposed to discharge fluid pressure from the discharge arc 206 based on the position of the teeth 212 of the gear 210.The connections between the slots 216a, 216b may allow all these connected slots 216a, 216b to experience discharge fluid pressure as a result of such intermittent exposure to discharge fluid pressure. In one embodiment, three radially extending slots 216a may be provided, the radially extending slots 216a being connected by circumferential slots 216b extending along the innermost and outermost ends of the radially extending slots 216a.

[0037] Figure 9 illustrates an end face of another bearing as an example to be used in one of the first and second gear trains, the end face of another such bearing being a mirror image. The end face 220 or a mirror image thereof may be provided at a face of fixed bearings 122a, 122b oriented towards the respective gears 114a, 114b, and / or at a face of movable bearings 124a, 124b oriented towards the respective gears 114a, 114b. The end face 220 includes the inlet region 202, the transition region 204, the discharge arc 206 and the outer channel 208 as described above. The gear 210, as described above and shown in [Fig.8], can be used with the bearing including the end face 220.

[0038] Slots 222 are provided in the transition region 204 of the end face 220. The slots 222 have sufficient width and depth to allow fluidic communication. In one embodiment, the slots 222 are provided entirely within the perimeter of the end face 220. In another embodiment, the slots 222 may be provided entirely within the transition region 204 of the end face 220. Each of the slots 222 extends radially opposite the axis of rotation of the gear 210. The slots 222 may be distributed above the transition region 204 or a portion thereof. The slots 222 can extend outwards in the radial direction from the roots 214 of the gear teeth 210. In one embodiment, the slots 222 reach an end before reaching an outer perimeter of the end face 220.At least one of the slots 222 can be positioned near the discharge arc 206. such that when the bearing including the end face 220 is used with the gear 210, said slot 222 is intermittently exposed to the discharge fluid pressure from the discharge arc 206 based on the position of the teeth 212 of the gear 210.

[0039] Figure 10 illustrates an end face of a bearing as a further example to be used in one of the first and second gear trains, the end face of another such bearing being a mirror image. The end face 240 or a mirror image thereof may be provided at a face of fixed bearings 122a, 122b oriented towards the respective gears 114a, 114b, and / or at a face of movable bearings 124a, 124b oriented towards the respective gears 114a, 114b. The end face 240 includes the inlet region 202, the transition region 204, the discharge arc 206 and the outer channel 208 as described above. The gear 210, as described above and shown in [Fig.8], can be used with the bearing including the end face 240.

[0040] Slots 242 are provided in the transition region 204 of the end face 240. The slots 242 have sufficient width and depth to allow fluidic communication. In one embodiment, the slots 242 are provided entirely within the perimeter of the end face 240. In another embodiment, the slots 242 may be provided entirely within the transition region 204 of the end face 240. Each of the slots 242 extends at an angle with respect to a radial direction extending from the axis of rotation. In one embodiment, the angle of inclination with respect to the radial direction may be the same for each of the slots 242. In another embodiment, the angle of inclination with respect to the radial direction may differ between at least two of the slots 242.In one embodiment, the slots 242 do not extend in the circumferential direction by more than the angular width of one of the teeth 212 when the bearing including the end face 240 is used with the gear 210. In one embodiment, the extent of the inclination may be such that when the bearing including the end face 240 is used with the gear 210, one or more of the slots 242 may provide a bypass allowing at least intermittent fluid communication through one or more of the teeth 212 of the gear 210, based on the rotational position of the gear 210. In one embodiment, at least one of the slots 242 is positioned such that said slot 242 may be intermittently exposed to discharge fluid pressure from the discharge arc 206 based on the position of the gear 210 when the bearing including an end face 240 is used with the gear 210. The 240 end is used with the 210 gear.. Aspects of Disclosure

[0041] Aspect 1. A gear stage of a pump, comprising: a housing defining a gear chamber, the housing defining an input and an output in fluidic communication with the gear chamber; an arrangement of gears disposed within the gear chamber configured to drive a fluid from the inlet to the outlet, the arrangement of gears including at least one gear capable of rotating about an axis of rotation; a trunnion coupled to the gear, the trunnion extending along the axis of rotation and configured to drive a rotation of the gear about the axis of rotation; a fixed bearing at a first axial side of the gear to radially support the trunnion relative to the housing so that the trunnion can rotate about the axis of rotation relative to the housing; and an axially movable bearing at a second opposite axial side of the gear to radially support the journal relative to the housing such that the journal can rotate about the axis of rotation relative to the housing, the axially movable bearing defining a through bore to receive the journal, the axially movable bearing being axially movable along the axis of rotation inside the journal in the direction and away from the gear, the axially movable bearing being fixed in rotation relative to the housing; in which: at least one of the fixed bearing and the axially movable bearing includes an end face oriented towards the gear, the end face including a transition region between an input region of said bearing and a discharge arc of said bearing, the end face including a plurality of slots formed in the transition region.

[0042] Aspect 2. The gear stage of the pump according to aspect 1, in which each of the plurality of slots is positioned radially outward from a root of a gear tooth relative to the axis of rotation.

[0043] Aspect 3. The pump gear stage according to any one of aspects 1 to 2, in which each of the plurality of slots is entirely in the transition region of the end face.

[0044] Aspect 4. The pump gear stage according to any one of aspects 1 to 3, in which each of the plurality of slots extends radially outwards with respect to the axis of rotation.

[0045] Aspect 5. The pump gear stage according to any one of aspects 1 to 3, in which each of the plurality of slots extends in a direction inclined with respect to a radial direction extending from the axis of rotation.

[0046] Aspect 6. The gear stage of the pump according to aspect 5, in which each of the plurality of slots is inclined such that one or more of the plurality of slots can provide a bypass allowing fluidic communication through a tooth of a gear.

[0047] Aspect 7. The pump gear stage according to any one of aspects 1 to 6, in which the plurality of slots are connected to each other by at least one slot extending in a circumferential direction with respect to the axis of rotation.

[0048] Aspect 8. The pump gear stage according to any one of aspects 1 to 7, in which the plurality of slots are spaced from the inlet region of said bearing by at least one angular width of one tooth-to-tooth spacing of the gear.

[0049] Aspect 9. The pump gear stage according to any one of aspects 1 to 8, wherein the end face further includes a circumferential groove extending in a circumferential direction with respect to the axis of rotation, the circumferential groove being in fluidic communication with a discharge fluid pressure of the pump gear stage.

[0050] Aspect 10. The gear stage of the pump according to aspect 9, in which each of the plurality of slots is separated from the circumferential groove on the end face.

[0051] Aspect 11. The gear stage according to any one of aspects 1 to 10, wherein the end face is a first end face, the plurality of slots is a first plurality of slots, and wherein the other of the fixed bearing and the axially movable bearing includes a second end face including a second transition region between an input region of said bearing and a discharge arc of said bearing, the second end face of said bearing including a second plurality of slots formed in the second transition region.

[0052] Aspect 12. The gear stage of the pump according to any one of aspects 1 to 11, wherein the journal is a first journal, the fixed bearing is a first fixed bearing, and the axially movable bearing is a first axially movable bearing, the gear stage further comprising: a second trunnion extending parallel to the first trunnion, the second trunnion driving another part of the gear arrangement; a second fixed bearing mounted on the second journal at the level of the first axial side of the gear arrangement; and a second axially movable bearing mounted on the second journal at the level of the second axial side of the gear arrangement.

[0053] Aspect 13. The gear stage according to aspect 12, wherein the end face is a first end face, the plurality of slots is a first plurality of slots, and wherein at least one of the second fixed bearing and the second axially movable bearing includes a second end face including a second transition region between an input region of said bearing and a discharge arc of said bearing, the second end face of said bearing including a second plurality of slots formed in the second transition region.

[0054] Aspect 14. A pump, including the pump gear stage according to one of aspects 1 to 13.

[0055] Aspect 15. A bearing for a gear stage of a pump, the bearing including: a body defining a through bore extending along a longitudinal axis between a first axial end and a second axial end, the second axial end including an end face, in which: the end face is configured to face a gear of the gear stage of the pump, the end face includes a transition region between an input region of said bearing and a discharge arc of the bearing, and the end face of the bearing includes a plurality of slots formed in the transition region.

[0056] Aspect 16. The bearing for a gear stage of a pump according to aspect 15, each of the plurality of slots being entirely in the transition region of the end face.

[0057] Aspect 17. The bearing for a gear stage of a pump according to any one of aspects 15-16, in which the plurality of slots are connected to each other by at least one slot extending in a circumferential direction with respect to the longitudinal axis.

[0058] Aspect 18. The bearing for a gear stage of a pump according to any one of aspects 15 to 17, in which each of the plurality of slots extends radially outwards with respect to the longitudinal axis.

[0059] Aspect 19. The bearing for a gear stage of a pump according to any one of aspects 15 to 17, in which each of the plurality of slots extends in a direction inclined with respect to a radial direction extending from the longitudinal axis.

[0060] Aspect 20. The bearing for a gear stage of a pump according to any one of aspects 15 to 19, in which the end face further includes a groove extending in a circumferential direction with respect to the longitudinal axis, the groove being in fluidic communication with a discharge fluid pressure of the gear stage of the pump.

[0061] Having described the preferred aspects and implementations of this disclosure, modifications and equivalents of the disclosed concepts may readily be apparent to a person skilled in the art. However, it is intended that these modifications and equivalents will be included within the scope of the claims annexed hereto.

Claims

1. Demands Gear stage (106) of a pump (100), comprising: a housing (116) defining a gear chamber (118), the housing (116) defining an inlet (102) and an outlet (104) in fluidic communication with the gear chamber (118); a gear arrangement (108) disposed inside the gear chamber (118) configured to drive fluid from the inlet to the outlet, the gear arrangement (108) including at least one gear (114, 114a, 114b) capable of rotating about an axis of rotation; a trunnion (120, 102a, 120b) coupled to the gear, the trunnion (120, 120a, 120b) extending along the axis of rotation and being configured to drive a rotation of the gear (114, 114a, 114b) around the axis of rotation; a fixed bearing (122a, 122b) at a first axial side of the gear to radially support the journal (120, 120a, 120b) relative to the housing (116) so that the journal (120, 120a, 120b) can rotate about the axis of rotation relative to the housing (116); and A movable bearing (124a, 124b) is axially positioned at a second, opposite axial side of the gear to radially support the journal (120, 120a, 120b) relative to the housing (116), such that the journal (120, 120a, 120b) can rotate about the axis of rotation relative to the housing (116). The axially movable bearing (124a, 124b) defines a through bore (132) to receive the journal (120, 120a, 120b). The axially movable bearing (124a, 124b) is axially movable along the axis of rotation inside the journal, in the direction and away from the gear (114, 114a, 114b). The axially movable bearing (124a, 124b) is rotationally fixed relative to the housing. (116); in which: at least one of the fixed bearing (122a, 122b) and the axially movable bearing (124a, 124b) includes an end face (140) oriented towards the gear, the end face including a transition region (142) between an input region of said bearing and a discharge arc (144) of said bearing, the end face (140) including a plurality of slots (146) formed in the transition region (142).

2. Gear stage (106) of the pump (100) according to claim 1, in which each of the plurality of slots (146) is positioned radially outward from a root of a gear tooth (114, 114a, 114b) relative to the axis of rotation.

3. Gear stage (106) of the pump (100) according to claim 1 or 2, wherein each of the plurality of slots (146) is entirely within the transition region (142) of the end face (140).

4. Gear stage (106) of the pump (100) according to claim 1 or 2, wherein each of the plurality of slots (146) extends in a direction inclined with respect to a radial direction extending from the axis of rotation, and each of the plurality of slots is inclined so that one or more of the plurality of slots can provide a bypass allowing fluidic communication through a tooth of a gear (114, 114a, 114b).

5. Gear stage (106) of the pump (100) according to any one of the preceding claims, wherein the plurality of slots (146) are connected to each other by at least one slot extending in a circumferential direction with respect to the axis of rotation.

6. Gear stage (106) of the pump (100) according to any one of the preceding claims, wherein the plurality of slots (146) are spaced from the inlet region of said bearing by at least one angular width of one tooth-to-tooth spacing of the gear.

7. Gear stage (106) of the pump (100) according to any one of the preceding claims, wherein the end face (140) further includes a first circumferential groove (148) in fluidic communication with a discharge fluid pressure of the gear stage of the pump, and each of the plurality of slots (146) is separated from the first circumferential groove (148) on the end face (140).

8. Gear stage (106) according to any one of the preceding claims, wherein the end face is a first end face, the plurality of slots is a first plurality of slots (146), and wherein the other of the fixed bearing (122a, 122b) and the axially movable bearing (124a, 124b) includes a second end face (172) including a second transition region between an input region of said bearing and a discharge arc of said bearing, the second face end (172) of said bearing including a second plurality of slots (178) formed in the second transition region (174).

9. Gear stage (106) of the pump (100) according to any one of the preceding claims, wherein the trunnion is a first trunnion (120a), the fixed bearing is a first fixed bearing (122a), and the axially movable bearing is a first axially movable bearing (124a), the gear stage (106) further comprising: a second trunnion (120b) extending parallel to the first trunnion (120a), the second trunnion (120b) driving another part of the gear arrangement (108); a second fixed bearing (122b) mounted on the second journal (120b) at the first axial side of the gear arrangement (108); and a second axially movable bearing (124b) mounted on the second journal (120b) at the second axial side of the gear arrangement (108), and in which the end face is a first end face, the plurality of slots is a first plurality of slots, and in which at least one of the second fixed bearing (122b) and the second axially movable bearing (124b) includes a second end face (172) including a second transition region between an inlet region of said bearing and a discharge arc (144) of said bearing, the second end face of said bearing including a second plurality of slots (178) formed in the second transition region (174).

10. Pump (100), including the gear stage (106) of the pump (100), according to any one of the preceding claims.