A hydraulic gear pump having a static pressure shaft bearing and spaced case outlets, and a method of operating the hydraulic gear pump

Abstract

An exemplary gear pump includes a pump ring gear, a pump shaft, a pump pinion assembled to the pump shaft and disposed within the pump ring gear, such that external teeth of the pump pinion engage internal teeth of the pump ring gear, and the pump shaft is configured to rotate the pump pinion, thereby rotating the pump ring gear engaged with the pump pinion and displacing fluid from an inlet chamber to an outlet chamber, one or more cross holes, a bushing disposed about the pump shaft, and a pocket formed about a portion of the bushing, the one or more cross holes fluidly connecting the outlet chamber to the pocket, such that fluid in the pocket applies a support force to the pump shaft.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 255,084, filed Oct. 13, 2021, which is hereby incorporated by reference in its entirety.

Background Art

[0002] Gear pumps use the meshing of gears to extrude fluid by displacement volume. There are two main variants: external gear pumps that use two external spur gears, and internal gear pumps that use an external spur gear (e.g., a pinion) and an internal spur gear (e.g., a ring). Gear pumps have a fixed displacement volume such that the pump can supply a fixed amount of fluid during each rotation.

[0003] In some cases, such as during stall conditions, a gear pump can operate in a state where the pump maintains the rated pressure with zero discharge flow. In other words, the pump maintains a high - pressure level at the pump's outlet port without supplying fluid flow from the pump. Under this condition, the gears of the pump rotate at a low speed under a high - torque load.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Under such conditions (e.g., stall conditions), it may be desirable to configure the pump to discharge a small amount of fluid from the pump to cool the internal components of the pump and to have a low - cost shaft bearing that operates at a low speed to support the high load on the pump shaft. The disclosure herein is presented in view of these and other considerations.

Means for Solving the Problems

[0005] The present disclosure describes embodiments related to a hydraulic gear pump having a hydrostatic shaft bearing and a spaced - apart case discharge port.

[0006] In a first exemplary implementation, the present disclosure describes a gear pump. The gear pump includes a pump ring gear, a pump shaft, and a pump pinion assembled to the pump shaft and disposed within the pump ring gear, wherein the external teeth of the pump pinion engage the internal teeth of the pump ring gear, the pump shaft is configured to rotate the pump pinion, thereby rotating the pump ring gear that engages the pump pinion and forcing fluid from an inlet chamber of the gear pump to an outlet chamber, a pump cover having one or more intersecting holes and pockets, and a bush disposed around the pump shaft, wherein an outer surface of the bush connects to an inner surface of the pump cover, the pockets are formed around a portion of the bush, one or more intersecting holes of the pump cover fluidly couple the outlet chamber to the pockets, whereby fluid within the pockets applies a supporting force to the pump shaft.

[0007] In a first exemplary implementation, the present disclosure describes a method. The method includes rotating a pump shaft of a gear pump, wherein a pump pinion is assembled to the pump shaft and disposed within a pump ring gear of the gear pump, the external teeth of the pump pinion engage the internal teeth of the pump ring gear, rotation of the pump shaft rotates the pump pinion, thereby rotating the pump ring gear that engages the pump pinion and forcing fluid from an inlet chamber of the gear pump to an outlet chamber, supplying fluid from the outlet chamber to pockets formed around a portion of a bush disposed around the pump shaft, applying a supporting force to the pump shaft by fluid within the pockets, and discharging the fluid applying the supporting force to a discharge port separated from the inlet chamber.

[0008] The above summary is illustrative only and is not intended to be limiting in any way. In addition to these exemplary aspects, implementations, and features described above, further aspects, implementations, and features will become apparent by reference to the drawings and the following detailed description.

[0009] The novel features believed to be characteristic of the exemplary examples are set forth in the appended claims. However, the exemplary examples and preferred modes of use, further objects and their descriptions will be best understood by reference to the following detailed description of the exemplary examples of the present disclosure when read in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0011] The present disclosure relates to a gear pump that can operate at a significant amount of time, zero discharge flow, and high pressure. The gear pump can generate a large shaft bearing load during operation. There are problems with applications that use conventional journal bearings and require low speed and long life. This is because at low speeds, the required hydrodynamic film necessary to sufficiently support the shaft cannot be generated. Roller element bearings can be used, but they are costly and impose weight.

[0012] Disclosed herein is a gear pump configured with a hydrostatic bearing, which is low-cost, effective at low speeds, small in size, and highly weight-efficient. In particular, to implement the hydrostatic bearing, the disclosed pump is configured to supply high-pressure leakage fluid directed towards the hydraulic region, and the high-pressure leakage fluid can supply a supporting force to the pump shaft.

[0013] Furthermore, the disclosed gear pump is configured to supply the fluid used to support the shaft within the hydrostatic bearing to an individual case discharge port to cool the internal components of the gear pump. The case discharge port is separated from the inlet so that the leakage fluid does not recirculate. Thus, the high-pressure leakage fluid is used to support the shaft through the hydrostatic bearing configuration and to cool the gear pump when the high-pressure leakage fluid is supplied to the separated case discharge port.

[0014] FIG. 1 shows a perspective partial view of a gear pump 100 according to an exemplary implementation, FIG. 2 shows a cross-sectional view of the gear pump 100 according to an exemplary implementation, and FIG. 3 shows a perspective exploded view of the gear pump 100 according to an exemplary implementation. FIGS. 1-3 will be described together.

[0015] The gear pump 100 has a pump housing 102 configured to house the components of the gear pump 100. The gear pump 100 further includes an end cover 104 connected to the pump housing 102. For example, several fasteners such as fastener 106 and fastener 108 can be arranged in a circular array and used to connect the end cover 104 to the pump housing 102.

[0016] In one example, the gear pump 100 may have another end cover that is connected to the pump housing 102 and assembled to the other end of the pump housing 102 opposite the end cover 104. In another example, the gear pump 100 can be part of a larger assembly including, for example, an electric motor. In this example, the electric motor can be connected to the gear pump 100 via the pump housing 102.

[0017] As shown in FIGS. 2 to 3, the gear pump 100 is configured as an internal gear pump having a pump pinion 110 (for example, a spur gear having external teeth formed on its outer peripheral surface) disposed within a pump housing 102 and a pump ring gear 112 (for example, a ring gear having internal teeth formed on its inner peripheral surface). The pump pinion 110 is assembled to or is an integral part of a pump shaft 114, and the teeth of the pump pinion 110 engage the teeth of the pump ring gear 112. Further, the pump pinion 110 is assembled offset with respect to the center of the pump ring gear 112. That is, the center of rotation of the pump pinion 110 is eccentric with respect to the center of rotation of the pump ring gear 112 or is displaced from the center of rotation of the pump ring gear 112. In the example, the pump shaft 114 can be rotatably connected via a spline 115 to a gear box or a rotor of a motor so as to impart a rotational movement to the pump pinion 110 and the pump ring gear 112 via the pump shaft 114.

[0018] The gear pump 100 can have an inlet port formed within a front cover, which is connected, for example, to the pump housing 102 or to an assembly including the gear pump 100. The inlet port provides fluid to an inlet passage 116 formed within the pump housing 102 as shown in FIG. 2. The gear pump 100 also has an outlet port 118 formed within the pump housing 102, through which fluid is discharged from the gear pump 100 to a hydraulic consumer, such as a hydraulic actuator. The gear pump 100 further has a discharge port 120 formed within an end cover 104. The discharge port 120 is separate from and spaced apart from the inlet port of the gear pump 100.

[0019] The pump ring gear 112 and the pump pinion 110 are axially supported within the pump housing 102 via (i) a first thrust plate 122 disposed distally of the pump ring gear 112 and the pump pinion 110, and (ii) a second thrust plate 124 disposed proximally of the pump ring gear 112 and the pump pinion 110. Accordingly, the pump pinion 110 and the pump ring gear 112 are interposed or sandwiched between the thrust plates 122 and 124.

[0020] The thrust plates 122, 124 are configured to be kidney-bean shaped as shown in FIG. 3. As will be described below, the thrust plates 122, 124 can operate as axial compensators that can reduce leakage within the gear pump 100 and improve the efficiency of the gear pump 100.

[0021] The thrust plates 122, 124 are supported by a first pump cover 126 and a second pump cover 128. In particular, as shown in FIG. 2, the first thrust plate 122 is axially interposed between the pump ring gear 112 and the first pump cover 126, and the first thrust plate 122 is connected to the first pump cover 126 at an interface surface 125. The second thrust plate 124 is axially interposed between the pump ring gear 112 and the second pump cover 128, and the second thrust plate 124 is connected to the second pump cover 128 at an interface surface 127. The term "interface surface" is used herein to denote the point, plane or space (or a portion of a plane or space) at which two components contact and interact (e.g., the thrust plates 122, 124 contact and interact with the respective pump covers 126, 128).

[0022] In this configuration, the components of the gear pump 100 are inserted between the pump covers 126 and 128 and supported by the pump covers 126 and 128. As shown in FIG. 2, the pump covers 126 and 128 each include a central through-hole for accommodating the pump shaft 114 therein. The thrust receiving plates 122 and 124 are not fastened to the pump covers 126 and 128, but are configured as floating components that can move axially, as will be described later, to fill any axial gaps and reduce internal leakage within the gear pump 100.

[0023] Furthermore, the gear pump 100 includes a bush 130 and a bush 132 disposed around the pump shaft 114 between the outer and inner surfaces of the pump covers 126 and 128 and the thrust receiving plates 122 and 124. Accordingly, the bush 130 is disposed at least partially within the pump cover 126, and the bush 132 is disposed at least partially within the pump cover 128. The bushes 130 and 132 are configured as bearings that facilitate the rotation of the pump shaft 114 and may be referred to as bush bearings, sleeve bearings, or journal bearings. Furthermore, as will be described in more detail below, the bushes 130 and 132 operate as hydrodynamic bearings that support the pump shaft 114 when the pump shaft 114 is at a low rotational speed.

[0024] Furthermore, as shown in FIG. 3, the gear pump 100 includes an inner crescent 134 and an outer crescent 136. The terms "inner" and "outer" indicate the radial arrangement of the crescents, and the inner crescent 134 is disposed radially inward of the outer crescent 136.

[0025] The inner crescent 134 and the outer crescent 136 are axially supported within the internal space between the pump ring gear 112 and the pump pinion 110 by a first positioning pin 138 connected to the second pump cover 128 and a second positioning pin 140 (partially shown in FIG. 3) connected to the first pump cover 126. The first positioning pin 138 is axially connected to the proximal ends of the crescents 134, 136. Similarly, the second positioning pin 140 is axially connected to the distal ends of the crescents 134, 136. In this configuration, the inner crescent 134 and the outer crescent 136 are axially held in a predetermined position by the positioning pins 138, 140, and the positioning pins 138, 140 also maintain the orientation of the crescents 134, 136.

[0026] During operation, fluid passes through the inlet port and then through the inlet passage 116 and is supplied to the inlet chamber 142 shown in FIG. 2. As the pump shaft 114 rotates, the pump pinion 110 rotates, and due to the engagement of the teeth of the pump pinion 110 and the pump ring gear 112, the pump ring gear 112 is rotated together with the pump pinion 110.

[0027] As described above, the center of rotation of the pump pinion 110 is offset from the center of rotation of the pump ring gear 112. Thus, when the outer teeth of the pump pinion 110 and the inner teeth of the pump ring gear 112 separate or disengage, an expanding volume portion (i.e., an expanding chamber) is brought about. The expanding volume portion collectively represents a plurality of pockets formed between the separating teeth. The expanding volume portion operates as a suction cavity formed between the separating teeth on the inlet side of the gear pump 100 that is fluidly connected to the inlet chamber 142, and the inlet chamber 142 is fluidly connected to the inlet port via the inlet passage 116.

[0028] As shown in FIG. 3, the pump ring gear 112 has a plurality of radial intersection holes such as intersection holes 144 that are circumferentially arranged around the pump ring gear 112. Fluid from the inlet chamber 142 flows not only from the distal and proximal ends of the pump ring gear 112 but also through the radial intersection holes of the pump ring gear 112 to fill the expanding volume portions between the teeth.

[0029] FIG. 4 shows a partial front cross-sectional view of the gear pump 100 according to an exemplary implementation. As the pump pinion 110 and the pump ring gear 112 rotate, the gear teeth of the pump pinion 110 and the pump ring gear 112 mesh, displacing the fluid. In other words, as the teeth of the pump pinion 110 and the pump ring gear 112 mesh on the discharge side of the gear pump 100, the volume is reduced and the fluid is forced out through the radial intersection holes of the pump ring gear 112 under pressure into the outlet chamber 146 shown in FIG. 4 and then out the outlet port 118.

[0030] When the teeth of the pump pinion 110 and the pump ring gear 112 mesh, these teeth form a seal between the expanding volume portion having the low-pressure fluid received from the inlet port and the volume portion connected to the outlet port 118 between the meshing or about-to-mesh teeth. The seal created by the tooth meshing forces the fluid out of the discharge port and prevents the fluid from flowing back.

[0031] Furthermore, as the pump pinion 110 and the pump ring gear 112 rotate, the crescents 134, 136 divide the fluid so that the fluid is carried from the low-pressure suction expanding volume portion to the outlet chamber 146 connected to the outlet port 118. Thus, the crescents 134, 136 can form a seal between the low-pressure volume portion and the high-pressure volume portion.

[0032] In particular, the outer surface (i.e., the radially outer surface) of the outer crescent 136 connects with the inner teeth of the pump ring gear 112 and creates a sealing portion therebetween. An effective sealing portion between the outer surface of the outer crescent 136 and the inner teeth of the pump ring gear 112 can prevent leakage from the high-pressure volume portion to the low-pressure volume portion. The terms "prevent" or "block" of fluid flow are used herein to indicate substantially preventing fluid flow, except for, for example, a minimum flow of a few drops per minute.

[0033] Similarly, the inner surface (i.e., the radially inner surface) of the inner crescent 134 connects with the outer teeth of the pump pinion 110 and creates a sealing portion therebetween. An effective sealing portion between the inner surface of the inner crescent 134 and the outer teeth of the pump pinion 110 can prevent leakage from the high-pressure volume portion to the low-pressure volume portion.

[0034] The configuration of the crescents 134, 136 provides an effective sealing portion, compensates for the radial gap between the crescents 134, 136 and the gear teeth, and creates an effective sealing portion. In particular, fluid from either the expansion volume portion or the high-pressure volume portion that oozes through the interface between the outer crescent 136 and the inner crescent 134 can push the crescents 134, 136 radially apart. In particular, the fluid between the crescents 134, 136 can push the outer crescent 136 radially outward toward the inner teeth of the pump ring gear 112, thereby eliminating any radial space or gap therebetween and forming an effective sealing portion. Similarly, the fluid between the crescents 134, 136 can push the inner crescent 134 radially inward toward the outer teeth of the pump pinion 110, thereby eliminating any radial space or gap therebetween and forming an effective sealing portion.

[0035] As shown in FIG. 3, on the distal side of the pump pinion 110 and the pump ring gear 112, the first thrust plate 122 can have through holes such as the through hole 148, enabling fluid communication of the high-pressure fluid on the discharge side (e.g., from the outlet chamber 146), and flowing it into the blind hole 150 formed in the pump cover 126 shown in FIG. 2. Similarly, on the proximal side of the pump pinion 110 and the pump ring gear 112, the second thrust plate 124 can have through holes such as the through hole 152, enabling fluid communication of the high-pressure fluid on the discharge side (e.g., from the outlet chamber 146), and flowing it into the blind hole 154 formed in the pump end cover 126 shown in FIG. 2. Thus, the high-pressure fluid in the outlet chamber 146 (see FIG. 4) can axially pass through in both directions through the through holes 148, 152 in the thrust plates 122, 124. Thus, the high-pressure fluid reaches the respective interfaces 125, 127 between the thrust plates 122, 124 and the pump covers 126, 128.

[0036] The fluid trapped at the interface 125 between the first thrust plate 122 and the first pump cover 126 applies an axial flow force on the first thrust plate 122 towards the distal end faces of the pump pinion 110 and the pump ring gear 112. Thus, a metal-to-metal seal is created between the first thrust plate 122 and the distal end faces of the pump pinion 110 and the pump ring gear 112. Similarly, the fluid trapped at the interface 127 between the second thrust plate 124 and the second pump cover 128 applies an axial flow force on the second thrust plate 124 towards the proximal end faces of the pump pinion 110 and the pump ring gear 112. Thus, a metal-to-metal seal is created between the second thrust plate 124 and the proximal end faces of the pump pinion 110 and the pump ring gear 112.

[0037] The fluid forces acting on the thrust plates 122, 124 towards the pump pinion 110 and the pump ring gear 112 axially push or advance the thrust plates 122, 124 against the pump pinion 110 and the pump ring gear 112, thereby creating an effective seal and eliminating any axial gap therebetween. Thus, the thrust plates 122, 124 can be referred to as axial compensators. This is because the thrust plates 122, 124 can compensate for any axial gap between the thrust plates 122, 124 and the pump pinion 110 and the pump ring gear 112 disposed therebetween, thereby reducing leakage and improving the efficiency of the gear pump 100.

[0038] Referring to FIG. 3, the gear pump 100 includes a first set of kidney bean-shaped seals 156, and the first set of kidney bean-shaped seals 156 can be disposed within a contoured cavity or recess on the proximal side of the first pump cover 126, and the recess has a shape that conforms to the shape of the first set of kidney bean-shaped seals 156. Thus, the first set of kidney bean-shaped seals 156 can be placed on the proximal side of the first pump cover 126 facing the first thrust plate 122. In this configuration, the first set of kidney bean-shaped seals 156 separates or seals the high-pressure fluid (from the high-pressure volume) communicating with the interface 125 from the low-pressure fluid supplied to the inlet passage 116. Thus, the first set of kidney bean-shaped seals 156 can prevent cross-flow or leakage from the high-pressure side to the low-pressure side.

[0039] Similarly, the gear pump 100 can include a second set of kidney-bean-shaped seals 158, and the second set of kidney-bean-shaped seals 158 are disposed within a contoured cavity or recess on the distal side of the second pump cover 128, and the recess has a shape that conforms to the shape of the second set of kidney-bean-shaped seals 158. Accordingly, the second set of kidney-bean-shaped seals 158 are placed on the distal side of the second pump cover 128 facing the second thrust plate 124. The second set of kidney-bean-shaped seals 158 can separate or seal high-pressure fluid (from the high-pressure volume) communicating with the interface surface 127 from low-pressure fluid. Accordingly, the second set of kidney-bean-shaped seals 158 can prevent cross-flow or leakage from the high-pressure side to the low-pressure side.

[0040] In one example, each of the sets of kidney-bean-shaped seals 156, 158 can include a primary seal and a backup seal. In another example, each of the sets of kidney-bean-shaped seals 156, 158 can include a primary seal and a seal support layer.

[0041] Under some operating conditions, such as stall conditions, the gear pump 100 may need to maintain a rated pressure (e.g., 3000 pounds per square inch) at the outlet port 118 while not discharging fluid from the outlet port 118. For example, if the gear pump 100 is supplying fluid to a hydraulic actuator (e.g., a hydraulic cylinder) and the hydraulic actuator needs to hold a load without moving the hydraulic actuator, the gear pump 100 may need to maintain a rated pressure sufficient to hold this load without supplying fluid flow.

[0042] Under such conditions, the pump shaft 114 can rotate at a low speed (e.g., 50 - 200 revolutions per minute) and receives a high torque load to maintain the rated pressure without supplying a significant fluid flow. In other words, the pump pinion 110 and the pump ring gear 112 (and the pump shaft 114) rotate at a low speed under a high torque load.

[0043] While fluid is not being discharged from the outlet port 118 under such conditions, a certain amount of leakage fluid is generated to facilitate maintaining the rated pressure when the pump shaft 114 rotates at a low speed. The gear pump 100 is configured to use such leakage fluid to support the load on the pump shaft 114, send fluid to the discharge port 120 separated from the inlet port, remove heat, and cool the gear pump 100.

[0044] As described above, the blind holes 150, 154 send high-pressure fluid to the interface surfaces 125, 127, and push the thrust-receiving plates 122, 124 against the pump pinion 110 and the pump ring gear 112. Further, the pump covers 126, 128 each have an intersecting hole, and the intersecting holes send the high-pressure fluid in the blind holes 150, 154 to the bushings 130, 132 respectively, promoting the operation of the bushings 130, 132. This is because the hydrodynamic bearing can support the load on the pump shaft 114 when the pump shaft 114 rotates at a low speed.

[0045] FIG. 5 shows a partial front view of the gear pump 100 according to an exemplary implementation. As shown, the second pump cover 128 has an intersecting hole, and the intersecting hole is configured to send the high-pressure fluid in the blind hole 154 around a portion of the bushing 132, for example, to a groove or pocket 500 formed under the bushing 132.

[0046] In particular, the second pump cover 128 has one or more intersecting holes configured to pass high-pressure fluid from the blind hole 154 to the pocket 500. For example, the pump cover 128 may include a first intersecting hole 502 intersectingly drilled in the second pump cover 128 so as to reach the blind hole 154. The second intersecting hole 504 is intersectingly drilled in the second pump cover 128 to fluidly connect the first intersecting hole 502 to the third intersecting hole 506, and the third intersecting hole 506 is also intersectingly drilled in the second pump cover 128.

[0047] As used herein, the term "intersecting hole" includes any kind of opening (e.g., a small hole, a window, a hole, etc.) that intersects the path of another hole, cavity, or passageway, or is formed transversely thereto. The intersecting holes 502-506 are cross-drilled in the second pump cover 128 and then plugged via plugs 508, plug 510, and plug 512, respectively.

[0048] Accordingly, the high-pressure fluid received from the blind hole 154 is passed through the first intersecting hole 502 and the second intersecting hole 504 to the third intersecting hole 506. Next, the third intersecting hole 506 supplies the high-pressure fluid to the pocket 500.

[0049] FIG. 6 shows another cross-sectional view of the gear pump 100 according to an exemplary implementation. The cross-sectional view of FIG. 6 is taken across a plane different from the plane of the cross-sectional view of FIG. 2. In the cross-sectional view of FIG. 6, the third intersecting hole 506 is shown within the second pump cover 128.

[0050] As shown in FIG. 6, the bush 132 has an intersecting hole 600 and an intersecting hole 602. The intersecting hole 600 can receive high-pressure fluid from the outlet chamber 146 that is flowing to the outer surface of the bush 132 through an unsealed space. Next, the fluid is passed into the bush 132 at the interface between the inner surface of the bush 132 and the outer surface of the pump shaft 114. This high-pressure fluid supports the pump shaft 114 from one side (e.g., the upper side).

[0051] The intersecting holes 502-506 are configured to supply high-pressure fluid to the opposite side of the bush 132. Referring to FIGS. 5-6 together, the high-pressure fluid in the blind hole 154 passes through the first intersecting hole 502, then through the second intersecting hole 504 and the third intersecting hole 506, and flows into the pocket 500. As shown in FIG. 6, the pocket 500 is fluidly connected to and aligned with the intersecting hole 602 of the bush 132. Thus, the high-pressure fluid is supplied to the interface between the inner surface of the bush 132 and the outer surface of the pump shaft 114 on the opposite side (e.g., the bottom side) of the bush 132.

[0052] In this configuration, the bush 132 operates as a hydrostatic bearing in which the pump shaft 114 is disposed. In particular, when the pump shaft 114 rotates at a low speed and fluid is not discharged from the outlet port 118, the high-pressure fluid obtained from the rotation of the pump pinion 110 and the pump ring gear 112 can be regarded as a leakage fluid flow. Such a leakage fluid flow is substantially supplied to a pocket 500 disposed below the bush 132, and then the fluid passes through the cross hole 602 and is supplied into the bush 132 at the interface between the inner surface of the bush 132 and the outer surface of the pump shaft 114. The high-pressure fluid applies a radially inward force on the pump shaft 114, and this radially inward force counteracts or provides a supporting force against the weight of the pump shaft 114 and any torque load applied to the pump shaft 114 during stall (low-speed) conditions.

[0053] Accordingly, the bush 132 operates as a sleeve or housing of a hydrostatic journal bearing and supports a radial load acting in a direction orthogonal to the longitudinal axis 604 of the pump shaft 114. The radial load is a downward load on the pump shaft 114 or due to the weight of the pump shaft 114. The bush 130 is configured similarly to the bush 132, the first pump cover 126 is configured similarly to the second pump cover 128, and the bush 130 operates as another hydrostatic bearing for the pump shaft 114 that is axially spaced from the bush 132 along the longitudinal axis 604 of the pump shaft 114.

[0054] In particular, the first pump cover 126 has a plurality of cross holes including the cross hole 606 shown in FIG. 6 and can supply high-pressure fluid from the blind hole 150 (see FIG. 2) to a pocket 608 similar to the pocket 500. The bush 130 includes cross holes 610 and 612 that are similar to the cross holes 600 and 602 of the bush 132, respectively. Accordingly, the pocket 608 supplies high-pressure fluid to the cross hole 612 and then to the interface between the inner surface of the bush 130 and the outer surface of the pump shaft 114 to support the pump shaft 114 at a low rotational speed.

[0055] The bushes 130, 132 span the pump pinion 110 and the pump ring gear 112 and are axially spaced along the length portion of the pump shaft 114. This configuration can provide improved support for the pump shaft 114.

[0056] If the leakage fluid flow supplied to the pockets 500, 608 to support the pump shaft 114 allows for the confluence of the inlet fluid received at the inlet port, the fluid recirculates without entering the cryogenic fluid into the gear pump 100. The recirculating fluid passing through the gear pump 100 can limit the amount of heat that may be removed. Further, a large pressure drop results from the high-pressure level of fluid discharged by the pump pinion 110 and the pump ring gear 112, and the fluid supplied back to the inlet port having fluid at a low pressure (e.g., atmospheric pressure). Such a large pressure drop represents a loss of power in the form of heat generated from the gear pump 100. In other words, such a leakage fluid flow may not be effective in cooling the gear pump 100 during a stall condition where the fluid is not discharged from the gear pump 100.

[0057] To mitigate this problem, the gear pump 100 is configured to supply the leakage fluid flow to the discharge port 120, which is separated from the inlet port and disposed downstream of the pocket 500. For example, the fluid supplied from the pocket 500 flows through the cross-hole 602 to the interface between the inner surface of the bush 132 and the outer surface of the pump shaft 114, and then is pushed or discharged into the chamber 614 formed within the end cover 104 and then flows to the discharge port 120. In another exemplary implementation, the fluid can be induced through a hole in the pump shaft 114 and then through a passage through the pump shaft 114 to the chamber 614.

[0058] Thus, the fluid drawn from the inlet port to generate the leakage fluid does not recirculate back to the inlet port. Further, the discharge port 120 can have a higher pressure level than the fluid supplied to the inlet port of the gear pump 100. Thus, the pressure drop between the high-pressure fluid supplied to the pocket 500 and the high-pressure fluid supplied to the discharge port 120 is smaller compared to the pressure drop between the fluid supplied to the pocket 500 and the fluid supplied to the inlet port. Thus, the supply of the leakage fluid to the discharge port 120 can improve the cooling of the gear pump 100 under stall and low-speed conditions.

[0059] The above description relates to an internal gear pump as an example of an illustration, but an implementation form in which high-pressure fluid is supplied to a bush to support a pump shaft and the fluid is discharged to a separated port can be applied to an external gear pump.

[0060] FIG. 7 is a flowchart of a method 700 for operating a gear pump 100 according to an exemplary implementation form. The method 700 can include one or more operations, functions, or actions exemplified by one or more of blocks 702-708. The blocks are shown in a sequential order, but these blocks may be performed in parallel and / or in an order different from the order described herein. Also, the various blocks may be combined into fewer blocks, divided into further blocks, and / or removed based on the desired implementation form. For this and other processes and methods disclosed herein, it should be understood that the flowchart shows the functions and operations of one possible implementation form of this example. As will be understood by a person of ordinary skill in the art, alternative implementation forms are included within the scope of the examples of the present disclosure, and the functions may be performed out of the order shown or described, including substantially simultaneously or in reverse order, depending on the related functions.

[0061] In block 702, method 700 includes rotating pump shaft 114 of gear pump 100, where pump pinion 110 is assembled to pump shaft 114 and disposed within pump ring gear 112 of gear pump 100, and the external teeth of pump pinion 110 engage the internal teeth of pump ring gear 112 such that rotation of pump shaft 114 rotates pump pinion 110, thereby rotating pump ring gear 112 that engages pump pinion 110, and forcing fluid from an inlet chamber (e.g., inlet chamber 142) of gear pump 100 to an outlet chamber (e.g., outlet chamber 146).

[0062] In block 704, method 700 includes supplying fluid from the outlet chamber to a pocket (e.g., pocket 500 or pocket 608) formed around a portion of a bush (e.g., bush 130 or bush 132) disposed around pump shaft 114.

[0063] In block 706, method 700 includes applying a support force to pump shaft 114 by the fluid within the pocket.

[0064] In block 708, the method includes discharging the fluid applying the support force to a discharge port 120 separated from the inlet chamber.

[0065] Method 700 may further include other steps described throughout this specification. For example, gear pump 100 can include a pump cover (e.g., first pump cover 126 or second pump cover 128), the pump cover includes a pocket and one or more cross holes (e.g., cross holes 502 - 506) fluidly connecting the outlet chamber to the pocket, and the supply of fluid from the outlet chamber to the pocket includes passing fluid from the outlet chamber to the pocket through the one or more cross holes.

[0066] In one example, the one or more crossover holes include (i) a first crossover hole 502 fluidly connected to the outlet chamber, (ii) a second crossover hole 504 fluidly connected to the first crossover hole 502, and (iii) a third crossover hole 506 fluidly connecting the second crossover hole 504 to the pocket 500. Passing fluid from the outlet chamber through the one or more crossover holes to the pocket includes passing fluid from the outlet chamber through the first crossover hole 502 to the second crossover hole 504, passing fluid from the second crossover hole 504 through the third crossover hole 506, and passing fluid from the third crossover hole 506 to the pocket 500.

[0067] The gear pump may further include a thrust plate (e.g., the first thrust plate 122 or the second thrust plate 124) axially inserted between the pump cover and the pump ring gear. The thrust plate can include a through hole (e.g., the through hole 148 or the through hole 152) fluidly connected to the outlet chamber. The pump cover includes a blind hole (e.g., the blind hole 150 or the blind hole 154), and the blind hole receives fluid from the through hole of the thrust plate and is fluidly connected to the first crossover hole 502 of the pump cover. Passing fluid from the outlet chamber through the first crossover hole includes passing fluid from the outlet chamber through the through hole of the thrust plate to the blind hole and passing fluid from the blind hole through the first crossover hole to the second crossover hole.

[0068] Further, the bushing (e.g., the bushing 132) has a crossover hole (e.g., the crossover hole 602) fluidly connected to the pocket. The method can further include passing fluid from the pocket into the bushing through the crossover hole of the bushing at the interface between the outer surface of the pump shaft 114 and the inner surface of the bushing, whereby the fluid applies a support force to the pump shaft 114.

[0069] In addition to the first bush (e.g., bush 130), the gear pump 100 can further include a second bush (e.g., bush 132) disposed around the pump shaft 114 proximal to the pump ring gear. The method can further include supplying fluid from the outlet chamber to respective pockets (e.g., pocket 500) formed around a portion of the second bush, whereby the fluid in each pocket applies a respective support force to the pump shaft 114.

[0070] The detailed description above explains various features and operations of the disclosed system with reference to the accompanying drawings. The exemplary implementations described herein are not meant to be limiting. Some aspects of the disclosed system can be configured and combined in a variety of different configurations. All of these are contemplated herein.

[0071] Furthermore, unless the context otherwise suggests, the features shown in each of the drawings can be used in combination with each other. Thus, the drawings should generally be seen as aspects of the components of one or more overall implementations, and it should be understood that not all of the features shown are necessary for each implementation.

[0072] Moreover, any enumeration of elements, blocks, or steps in this specification or the claims is for clarity purposes. Thus, such enumeration should not be construed as requiring or implying that these elements, blocks, or steps adhere to a particular configuration or are executed in a particular order.

[0073] Furthermore, the device or system can be used or configured to implement the functions presented in the drawings. In some examples, the components of the device and / or system can be configured to perform some functions, and these components are actually configured and structured (by hardware and / or software) to enable such implementation. In other examples, the components of the device and / or system can be configured to be suitable for, capable of, or adapted to the implementation of functions when operating in a particular manner, etc.

[0074] The term "substantially" does not require precisely achieving the recited characteristics, parameters, or values. For example, deviations or variations including tolerances, measurement errors, limits of measurement accuracy, and other factors known to those skilled in the art can occur in an amount that does not prevent the effect intended to be provided by the characteristic.

[0075] The configurations described herein are merely examples. Thus, those skilled in the art will understand that other configurations and other elements (such as machines, interfaces, operations, sequences, and groupings of sequences, etc.) can be used instead, and some elements can be completely omitted depending on the desired results. Furthermore, many of the elements described can be functional entities that can be implemented in any suitable combination and location, either individually or as distributed components, or together with other components.

[0076] Although various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for illustrative purposes and not intended to be limiting, and the true scope is indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. Also, the terms used herein are for the purpose of describing particular implementations only and are not intended to be limiting.

[0077] Accordingly, an embodiment of the present disclosure can relate to one of the following enumerated example embodiments (EEE).

[0078] EEE1 is a gear pump. The gear pump includes a pump ring gear, a pump shaft, and a pump pinion assembled to the pump shaft and disposed within the pump ring gear. The external teeth of the pump pinion engage with the internal teeth of the pump ring gear. The pump shaft is configured to rotate the pump pinion, thereby rotating the pump ring gear that engages with the pump pinion and displacing the fluid from the inlet chamber to the outlet chamber of the gear pump. It also includes a pump pinion, a pump cover having one or more intersecting holes and pockets, and a bush disposed around the pump shaft. The outer surface of the bush connects to the inner surface of the pump cover. The pockets are formed around a portion of the bush. One or more intersecting holes of the pump cover fluidly connect the outlet chamber to the pockets, whereby the fluid in the pockets applies a supporting force to the pump shaft.

[0079] EEE2 is the gear pump of EEE1 and further includes a thrust receiving plate axially inserted between the pump cover and the pump ring gear. The thrust receiving plate has a through hole fluidly connected to the outlet chamber. The pump cover has a blind hole for receiving the fluid from the through hole of the thrust receiving plate. One of the one or more intersecting holes of the pump cover is fluidly connected to the blind hole.

[0080] EEE3 is the gear pump of EEE2. The one or more intersecting holes include a first intersecting hole fluidly connected to the blind hole, a second intersecting hole fluidly connected to the first intersecting hole, and a third intersecting hole fluidly connecting the second intersecting hole to the pockets.

[0081] EEE4 is the gear pump of any one of EEE1 - 3. The bush has intersecting holes fluidly connected to the pockets and configured to allow fluid to pass from the pockets into the bush at the interface between the outer surface of the pump shaft and the inner surface of the bush, whereby the fluid applies a supporting force to the pump shaft.

[0082] EEE5 is any one of the gear pumps EEE1 - 4, and the pocket is formed under the bush.

[0083] EEE6 is any one of the gear pumps EEE1 - 5. The bush is the first bush disposed on the distal side of the pump ring gear. The pump cover is the first pump cover disposed on the distal side of the pump ring gear. The gear pump is disposed on the proximal side of the pump ring gear and further includes a second pump cover having one or more respective intersecting holes and respective pockets, and a second bush disposed around the pump shaft on the proximal side of the pump ring gear. The outer surface of the second bush is connected to the inner surface of the second pump cover, and each pocket is formed around a portion of the second bush. One or more respective intersecting holes of the pump cover are configured to fluidly connect the outlet chamber to each pocket, whereby the fluid in each pocket applies a respective support force to the pump shaft.

[0084] EEE7 is any one of the gear pumps EEE1 - 6 and further includes a discharge port. The discharge port is separated from the inlet chamber and is disposed downstream of the pocket to allow the fluid applying the support force to the pump shaft to flow to the discharge port.

[0085] EEE8 is the gear pump of EEE7 and further includes an end cover connected to the pump cover. The discharge port is formed within the end cover.

[0086] EEE9 is a method. The method is to rotate the pump shaft of a gear pump, where the pump pinion is assembled to the pump shaft of the gear pump and disposed within a pump ring gear. The external teeth of the pump pinion engage with the internal teeth of the pump ring gear. By rotating the pump shaft, the pump pinion is rotated, thereby rotating the pump ring gear that engages with the pump pinion, and pushing the fluid from the inlet chamber of the gear pump into the outlet chamber. It also includes supplying the fluid from the outlet chamber to a pocket formed around a portion of a bush disposed around the pump shaft, applying a supporting force to the pump shaft by the fluid within the pocket, and discharging the fluid applying the supporting force to a discharge port separated from the inlet chamber.

[0087] EEE10 is the method of EEE9, where the gear pump further includes a pump cover. The pump cover has a pocket and one or more cross holes fluidly connecting the outlet chamber to the pocket. The supply of fluid from the outlet chamber to the pocket includes passing the fluid from the outlet chamber through the one or more cross holes into the pocket.

[0088] EEE11 is the method of EEE10. The one or more cross holes include (i) a first cross hole fluidly connected to the outlet chamber, (ii) a second cross hole fluidly connected to the first cross hole, and (iii) a third cross hole fluidly connecting the second cross hole to the pocket. Passing the fluid from the outlet chamber through the one or more cross holes into the pocket includes passing the fluid from the outlet chamber through the first cross hole into the second cross hole, passing the fluid from the second cross hole through the third cross hole, and passing the fluid from the third cross hole into the pocket.

[0089] EEE12 is a method of EEE11, and the gear pump further includes a thrust receiving plate axially inserted between the pump cover and the pump ring gear. The thrust receiving plate has a through hole fluidly connected to the outlet chamber. The pump cover has a blind hole for receiving fluid from the through hole of the thrust receiving plate. Fluid communication with the first intersecting hole of the pump cover and passing fluid from the outlet chamber through the first intersecting hole includes passing fluid from the outlet chamber through the through hole of the thrust receiving plate to the blind hole and passing fluid from the blind hole through the first intersecting hole to the second intersecting hole.

[0090] EEE13 is a method of any one of EEE9 - 12. The bush has an intersecting hole fluidly connected to the pocket. The method further includes passing fluid from the pocket into the bush through the intersecting hole of the bush at the interface between the outer surface of the pump shaft and the inner surface of the bush, whereby the fluid applies a supporting force to the pump shaft.

[0091] EEE14 is a method of any one of EEE9 - 13. The bush is a first bush disposed on the distal side of the pump ring gear. The gear pump further includes a second bush disposed around the pump shaft on the proximal side of the pump ring gear. The method further includes supplying fluid from the outlet chamber to respective pockets formed around a portion of the second bush, whereby the fluid in each pocket applies a respective supporting force to the pump shaft.

[0092] EEE15 is a method of EEE9. The gear pump further includes an end cover. The discharge port is formed in the end cover. Discharging the fluid applying a supporting force to the discharge port includes passing the fluid applying the supporting force into a chamber formed in the end cover, and the chamber is fluidly connected to the discharge port.

Claims

1. A gear pump, wherein the gear pump comprises: a pump ring gear; a pump shaft; a pump pinion assembled to the pump shaft and disposed within the pump ring gear, wherein outer teeth of the pump pinion engage inner teeth of the pump ring gear, and the pump shaft is configured to rotate the pump pinion, thereby rotating the pump ring gear that engages the pump pinion to force fluid from an inlet chamber of the gear pump to an outlet chamber; a pump pinion; a pump cover having one or more intersecting holes and pockets; a bush disposed around the pump shaft; a thrust receiving plate axially inserted between the pump cover and the pump ring gear; wherein an outer surface of the bush is connected to an inner surface of the pump cover, the pockets are formed around a portion of the bush, and one or more intersecting holes of the pump cover fluidly connect the outlet chamber to the pockets, whereby fluid in the pockets applies a supporting force to the pump shaft; the thrust receiving plate has a through hole fluidly connected to the outlet chamber, the pump cover has a blind hole for receiving fluid from the through hole of the thrust receiving plate, and one of the one or more intersecting holes of the pump cover is fluidly connected to the blind hole; the one or more intersecting holes include a first intersecting hole fluidly connected to the blind hole; a second intersecting hole fluidly connected to the first intersecting hole; and a third intersecting hole fluidly connecting the second intersecting hole to the pockets; A gear pump.

2. A gear pump, wherein the gear pump comprises: a pump ring gear; a pump shaft; a pump pinion assembled to the pump shaft and disposed within the pump ring gear, wherein outer teeth of the pump pinion engage inner teeth of the pump ring gear, and the pump shaft is configured to rotate the pump pinion, thereby rotating the pump ring gear that engages the pump pinion to force fluid from an inlet chamber of the gear pump to an outlet chamber; a pump pinion; a pump cover having one or more intersecting holes and pockets; A bush disposed around the pump shaft, a discharge port and the outer surface of the bush is connected to the inner surface of the pump cover, the pocket is formed around a portion of the bush, and one or more intersecting holes in the pump cover fluidly connect the outlet chamber to the pocket, whereby the fluid in the pocket applies a support force to the pump shaft, the discharge port is isolated from the inlet chamber and is disposed downstream of the pocket, and a gear pump configured to allow fluid applying a support force to the pump shaft to flow to the discharge port. **Claim 3** The bush has intersecting holes configured to fluidly connect the pocket and to communicate fluid from the pocket into the bush at an interface between the outer surface of the pump shaft and the inner surface of the bush, whereby the fluid applies a support force to the pump shaft, the gear pump according to claim 1 or 2. **Claim 4** The pocket is formed under the bush, the gear pump according to claim 1 or 2. **Claim 5** The bush is a first bush disposed distally of the pump ring gear, the pump cover is a first pump cover disposed distally of the pump ring gear, and the gear pump further includes a second pump cover disposed proximally of the pump ring gear and having one or more respective intersecting holes and respective pockets, and a second bush disposed around the pump shaft proximally of the pump ring gear wherein the outer surface of the second bush is connected to the inner surface of the second pump cover, each pocket is formed around a portion of the second bush, and one or more respective intersecting holes in the pump cover are configured to fluidly connect the outlet chamber to each pocket, whereby the fluid in each pocket applies a respective support force to the pump shaft, the gear pump according to claim 1 or 2. **Claim 6** and further includes an end cover connected to the pump cover wherein the discharge port is formed in the end cover, the gear pump according to claim 2. **Claim 7** A method, the method comprising Rotating the pump shaft of a gear pump, wherein a pump pinion is assembled to the pump shaft and disposed within a pump ring gear of the gear pump, external teeth of the pump pinion engage internal teeth of the pump ring gear, rotation of the pump shaft rotates the pump pinion, thereby rotating the pump ring gear that engages the pump pinion, and pushing fluid from an inlet chamber of the gear pump to an outlet chamber by rotation; Supplying fluid from the outlet chamber to a pocket formed around a portion of a bush disposed around the pump shaft; Applying a supporting force to the pump shaft by the fluid within the pocket; Discharging the fluid applying the supporting force to a discharge port separated from the inlet chamber A method comprising the steps of.

8. The gear pump includes a pump cover, the pump cover includes the pocket, and has one or more intersecting holes fluidly connecting the outlet chamber to the pocket, and the supply of fluid from the outlet chamber to the pocket Passing fluid from the outlet chamber through the one or more intersecting holes to the pocket The method according to claim 7, comprising the steps of.

9. The one or more intersecting holes include (i) a first intersecting hole fluidly connected to the outlet chamber, (ii) a second intersecting hole fluidly connected to the first intersecting hole, and (iii) a third intersecting hole fluidly connecting the second intersecting hole to the pocket, and passing fluid from the outlet chamber through the one or more intersecting holes to the pocket Passing fluid from the outlet chamber through the first intersecting hole to the second intersecting hole; Passing fluid from the second intersecting hole to the third intersecting hole; Passing fluid from the third intersecting hole to the pocket The method according to claim 8, comprising the steps of.

10. The gear pump further includes a thrust receiving plate axially inserted between the pump cover and the pump ring gear, the thrust receiving plate includes a through hole fluidly connected to the outlet chamber, the pump cover includes a blind hole for receiving fluid from the through hole of the thrust receiving plate, fluidly connected to the first intersecting hole of the pump cover, and passing fluid from the outlet chamber through the first intersecting hole is passing fluid from the outlet chamber through the through hole of the thrust receiving plate to the blind hole and passing fluid from the blind hole through the first intersecting hole to the second intersecting hole The method according to claim 9, comprising.

11. The bush has an intersecting hole fluidly connected to the pocket, and the method includes passing fluid from the pocket through the intersecting hole of the bush into the bush at the interface between the outer surface of the pump shaft and the inner surface of the bush The method according to claim 7, further comprising, whereby the fluid applies a supporting force to the pump shaft.

12. The bush is a first bush disposed on the distal side of the pump ring gear, the gear pump further includes a second bush disposed around the pump shaft on the proximal side of the pump ring gear, and the method includes supplying fluid from the outlet chamber to respective pockets formed around a portion of the second bush The method according to claim 7, further comprising, whereby the fluid in each respective pocket applies a respective supporting force to the pump shaft.

13. The gear pump further includes an end cover, the discharge port is formed in the end cover, and discharging the fluid applying a supporting force to the discharge port is passing the fluid applying the supporting force into a chamber formed in the end cover The method according to claim 7, wherein the chamber is fluidly connected to the discharge port.

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