Assembly for an internal gear pump with a hydrostatic fluid support mechanism

Abstract

An exemplary gear pump comprising: a pump housing having a hydrostatic fluid groove; an outer bushing mounted on the pump housing and having a hydrostatic fluid slit fluid connection to the hydrostatic fluid groove of the pump housing; a drive flange, the drive flange mounted on the outer bushing so as to be inserted radially between the pump housing and the drive flange; a ring gear connected to the drive flange and configured to rotate with the drive flange; and a pump pinion, the pump pinion having an outer tooth row that engages with an inner tooth row of the ring gear and is positioned within the ring gear to draw in and discharge fluid as they rotate, the fluid being supplied to the hydrostatic fluid groove of the pump housing and communicating through the hydrostatic fluid slit fluid to the interface between the drive flange and the outer bushing to facilitate the rotation of the drive flange relative to the pump housing.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 493,003, filed on March 30, 2023, the entire content of which is hereby incorporated by reference as if fully set forth herein.

Background Art

[0002] Gear pumps utilize the meshing of gears to discharge fluid by displacement. There are two main variations, namely, an external gear pump using two external spur gears and an internal gear pump using one external spur gear (e.g., pinion) and one internal spur gear (e.g., ring). Gear pumps have a fixed displacement, in which case the pump can provide a fixed amount of fluid per rotation.

[0003] When the gears of the pump rotate, the gear teeth separate on the suction side of the pump, creating a void while suction occurs, and then this void is filled with fluid. The fluid is conveyed by the gears to the discharge or outlet side of the pump, and due to the meshing of the gears, the fluid is displaced under pressure. In some cases, the high - pressure fluid on the outlet side of the pump can push the ring gear of the internal gear pump towards the pump housing, thereby increasing the potential for wear due to friction. Therefore, in order to reduce wear, it is desirable to address the forces exerted on the gears by the high - pressure fluid.

[0004] In examples, an electric motor can be used to drive the pump. In these examples, it may be desirable to have an assembly that integrates the pump and the electric motor. This allows mechanical components such as shafts, bearings, etc. to be shared between the hydraulic pump and the motor. These considerations and other considerations disclosed herein are presented below.

Summary of the Invention

[0005] This disclosure describes embodiments relating to an assembly for an internal gear pump equipped with a hydrostatic fluid support mechanism.

[0006] In particular, the present disclosure describes an internal gear pump supported by a hydrostatic fluid journal bearing or bushing, having a hydrostatic fluid mechanism embedded in the bushing to improve the support of eccentric loads and improve the efficiency of the pump.

[0007] In an exemplary embodiment, the gear pump is integrated with the electric motor in the assembly. The bushing structure can improve the integration between the gear pump and the electric motor, reducing the number of components in the assembly and saving space.

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

[0009] Novel features that are considered characteristic of the exemplary embodiments are described in the appended claims. However, the exemplary embodiments, as well as preferred modes of use, further subjects and their descriptions, will be best understood by referring to the following detailed description of the exemplary embodiments of this disclosure when read in conjunction with the appended drawings. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a gear pump according to an exemplary embodiment. [Figure 2] This is a side cross-sectional view showing the gear pump of Figure 1 according to an exemplary embodiment. [Figure 3] This is an exploded perspective view showing the gear pump of Figure 1 according to another exemplary embodiment. [Figure 4] This is another cross-sectional view showing the gear pump of Figure 1 according to an exemplary embodiment. [Figure 5] This is a perspective view showing a first end cover according to an exemplary embodiment. [Figure 6] Figure 5 is a perspective view showing the first end cover together with a first outer bushing attached to the cylindrical projection of the first end cover, according to an exemplary embodiment. [Figure 7] This is a partially cross-sectional perspective view showing the first end cover of Figure 6 according to an exemplary embodiment. [Figure 8] This is a perspective view showing the cylindrical projection of the second end cover and the second outer bushing in the first operating mode, according to an exemplary embodiment. [Figure 9] This is a perspective view showing the cylindrical projection and the second outer bushing in the second operating mode according to an exemplary embodiment of Figure 8. [Figure 10] This is a perspective view showing a second end cover according to an exemplary embodiment. [Figure 11] Figure 1 is a side cross-sectional view showing an assembly of a gear pump and an electric motor integrated with the gear pump, according to an exemplary embodiment. [Figure 12] This is an exploded perspective view showing the assembly of Figure 11 according to an exemplary embodiment. [Modes for carrying out the invention]

[0011] This disclosure relates to a gear pump having a bush with a hydrostatic mechanism such that the bush acts as a hydrostatic bearing. The disclosure further relates to integrating the gear pump and an electric motor to have an assembly that provides a compact structure that reduces costs, saves space, and increases reliability by sharing components.

[0012] Figure 1 shows a perspective view of the gear pump 100 according to an exemplary embodiment, Figure 2 shows a side cross-sectional view of the gear pump 100, and Figure 3 shows an exploded perspective view of the gear pump 100. Figures 1 to 3 will be explained together.

[0013] The gear pump 100 has an assembly housing 102 mounted or inserted between a first end cover 104 (e.g., a front cover) and a second end cover 106 (e.g., a rear cover). The assembly housing 102 is generally cylindrical in shape and defines an internal chamber 103 containing the components of the gear pump 100, as shown in Figure 2.

[0014] The assembly housing 102 has a flange 108 that can be connected to the first end cover 104 via a plurality of fasteners, such as fasteners 109 (e.g., socket head bolts). Similarly, the second end cover 106 can be connected to the housing via a plurality of fasteners, such as fasteners 110.

[0015] Furthermore, as shown in Figure 1, the first end cover 104 may have ears such as ears 111, through which fasteners such as fasteners 112 can be placed. Fasteners such as fasteners 112 can be used to attach or connect the gear pump 100 to, for example, a machine frame. The second end cover 106 may have a first port 114, a second port 116, and a drain port 118.

[0016] Referring to FIGS. 2-3, the first end cover 104 has a cylindrical protrusion 120 extending axially or longitudinally within the assembly housing 102. The second end cover 106 also has a cylindrical protrusion 122 extending axially or longitudinally within the assembly housing 102 toward the cylindrical protrusion 120 of the first end cover 104. In another exemplary embodiment, the cylindrical protrusions 120, 122 may be separate components attached to their respective end covers. The cylindrical protrusions 120, 122 face each other, forming a space therebetween, and components of the gear pump 100 are disposed in this space, whereby the cylindrical protrusions 120, 122 surround or sandwich such components of the gear pump 100. Thus, the cylindrical protrusions 120, 122 are configured as a pump housing 123.

[0017] The cylindrical protrusion 120 has an annular groove or recess for accommodating the first outer bushing 124. Similarly, the cylindrical protrusion 122 has an annular groove or recess for accommodating the second outer bushing 126.

[0018] The gear pump 100 further includes a drive flange 128 generally in the shape of a cylinder. The gear pump 100 further includes a ring gear 130 inserted between the cylindrical protrusions 120, 122. In one example, the ring gear 130 is integrated with the drive flange 128 such that the ring gear 130 and the drive flange 128 are formed as one component. In another example, the ring gear 130 may be a separate component connected to the drive flange 128 (e.g., via a key-keyway arrangement, a spline arrangement, a self-retaining taper arrangement, etc.).

[0019] As shown in FIG. 2, the first outer bush 124 is inserted between the outer peripheral surface of the cylindrical protrusion 120 and the inner peripheral surface of the drive flange 128 in the radial direction. Similarly, the second outer bush 126 is inserted between the outer peripheral surface of the cylindrical protrusion 122 and the inner peripheral surface of the drive flange 128 in the radial direction. As will be described in more detail later, the outer bushes 124 and 126 operate as bearings that support the rotation of the drive flange 128 and the ring gear 130 with minimal friction.

[0020] As shown in FIG. 3, the ring gear 130 has an inner tooth row 131 formed on the inner peripheral surface of this ring gear. Referring to FIGS. 2 and 3 together, the gear pump 100 has a pump shaft 132, and a pump pinion 134 (for example, a spur gear having an outer tooth row 135 formed on its outer peripheral surface) is attached to or integrated with this pump shaft.

[0021] The outer tooth row 135 of the pump pinion 134 engages with the inner tooth row 131 of the ring gear 130. Further, the pump pinion 134 is attached eccentrically to the ring gear 130, that is, the rotation center of the pump pinion 134 is eccentric with respect to the respective rotation centers of the ring gear 130 or offset from the respective rotation centers of the ring gear 130.

[0022] The cylindrical protrusion 120 has a through hole 137 for accommodating the pump shaft 132, and a first inner bush 136 is inserted between the outer peripheral surface of the pump shaft 132 and the inner peripheral surface of the cylindrical protrusion 120 that defines the through hole 137 in the radial direction. Similarly, the cylindrical protrusion 122 has a hole or cavity 141 for accommodating the other end of the pump shaft 132, and a second inner bush 138 is inserted between the outer peripheral surface of the pump shaft 132 and the inner peripheral surface of the cylindrical protrusion 122 that defines the cavity 141 in the radial direction.

[0023] As will be described in more detail later, the inner bushings 136 and 138 act as bearings that support the rotation of the pump shaft 132 with minimal friction. The pump shaft 132 is positioned eccentrically from the ring gear 130, and the inner bushings 136 and 138 (supporting the pump shaft 132) are positioned eccentrically with respect to the outer bushings 124 and 126 (supporting the drive flange 128).

[0024] The cylindrical projection 120 includes a drain passage 139, and the cylindrical projection 122 includes a drain passage 140. The drain passage 139 allows a first inner bushing 136 to be fluidly connected to the fluid volume within the cylindrical projection 120, thereby preventing fluid stagnation that occurs when supporting the first inner bushing 136 which supports the rotation of the pump shaft 132 and the pump pinion 134. Similarly, the drain passage 140 allows a second inner bushing 138 to be fluidly connected to the fluid volume within the cylindrical projection 122, thereby preventing fluid stagnation that occurs when supporting the second inner bushing 138 which supports the rotation of the pump shaft 132 and the pump pinion 134.

[0025] The ring gear 130 and pump pinion 134 are axially supported within the assembly housing 102 via (i) a first thrust plate 142 located on one side of the ring gear 130 and pump pinion 134, and (ii) a second thrust plate 144 on the other side of the ring gear 130 and pump pinion 134. Thus, the pump pinion 134 and ring gear 130 are inserted or sandwiched between the thrust plates 142, 144. As will be described later, the thrust plates 142, 144 can act as axial compensators that can reduce leakage within the gear pump 100 and improve efficiency.

[0026] The thrust plates 142 and 144 themselves are supported by cylindrical projections 120 and 122. In particular, thrust plate 142 forms an interface with cylindrical projection 120, and thrust plate 144 forms an interface with cylindrical projection 122. The term “interface” is used herein to describe a point, plane, or space (or part of a plane or space) where two components contact and interact (for example, where thrust plates 142 and 144 contact and interact with cylindrical projections 120 and 122, respectively). The thrust plates 142 and 144 are formed as floating components that can move axially, as described later, thereby creating arbitrary axial gaps and reducing internal leakage within the gear pump 100.

[0027] With this structure, the components of the gear pump 100 are inserted between the cylindrical projections 120 and 122 of the end covers 104 and 106 and supported by them. As shown in Figures 2 and 3, the thrust plates 142 and 144 each include a through hole through which the pump shaft passes to accommodate the pump shaft 132.

[0028] Figure 4 shows another cross-sectional view of the gear pump 100 according to an exemplary embodiment. The plane from which the cross-sectional view of Figure 4 is taken may be perpendicular to, for example, the plane from which the cross-sectional view of Figure 2 is taken.

[0029] Referring to Figures 3 and 4, the cylindrical projection 120 has a first fluid cavity 146 and a second fluid cavity 148. The fluid cavities 146 and 148 extend axially in the cylindrical projection 120. In one example, the fluid cavities 146 and 148 are kidney-shaped when viewed longitudinally in the cylindrical projection 120, as shown in Figure 3.

[0030] Similarly, the cylindrical projection 122 has a first fluid cavity 150 and a second fluid cavity 152. The fluid cavities 150 and 152 extend axially in the cylindrical projection 120. In one example, the fluid cavities 150 and 152 may also be kidney-shaped.

[0031] Furthermore, the thrust plates 142 and 144 may each have fluid passages aligned with the fluid cavities 146 to 152. In particular, the first thrust plate 142 may have a fluid passage 154 aligned with the first fluid cavity 146 of the cylindrical projection 120 and the first fluid cavity 150 of the cylindrical projection 122. The first thrust plate 142 may also have a fluid passage 156 aligned with the second fluid cavity 148 of the cylindrical projection 120 and the second fluid cavity 152 of the cylindrical projection 122.

[0032] Similarly, the second thrust plate 144 may have a fluid passage 158 aligned with the first fluid cavity 146 of the cylindrical projection 120 and the first fluid cavity 150 of the cylindrical projection 122. The second thrust plate 144 may also have a fluid passage 160 aligned with the second fluid cavity 148 of the cylindrical projection 120 and the second fluid cavity 152 of the cylindrical projection 122.

[0033] The fluid passages 154-160 of the thrust plates 142,144 may also be kidney-shaped to conform to the shape of the fluid cavities 146-152. In the example, the thrust plates 142,144 may have grooves around the fluid passages 154-160, and kidney-shaped seals may be placed in these grooves to seal each passage and prevent cross-flow between them.

[0034] The first fluid cavity 150 is in fluid communication or fluid connection with the first port 114, and the second fluid cavity 152 is in fluid communication or fluid connection with the second port 116. With this structure, the first fluid cavity 146, fluid passage 154, fluid passage 158, and the first fluid cavity 150 are aligned with and in fluid communication with the first port 114. Similarly, the second fluid cavity 148, fluid passage 156, fluid passage 160, and the second fluid cavity 152 are aligned with and in fluid communication with the second port 116.

[0035] The gear pump 100 is configured to operate as a bidirectional pump. In particular, the first port 114 can operate as an inlet port configured to receive fluid from a fluid reservoir or hydraulic actuator fluid-connected to the gear pump 100 (e.g., via a hose or any hydraulic conduit), and the second port 116 can operate as an outlet or discharge port for providing pressurized fluid to be discharged from the gear pump 100 to a hydraulic actuator fluid-connected to the gear pump 100. The hydraulic actuator may be, for example, a hydraulic cylinder having a piston that moves linearly inside, or a hydraulic motor. In this operating mode, the pump pinion 134 and the ring gear 130 rotate in a first rotational direction, and the hydraulic actuator may move in a first direction.

[0036] In an alternative operating mode, the first port 114 can function as a discharge port for providing pressurized fluid to be discharged from the gear pump 100 to the hydraulic actuator, and the second port 116 can function as an inlet port configured to receive fluid from a fluid reservoir. In this operating mode, the pump pinion 134 and the ring gear 130 rotate in a second rotation direction opposite to the first rotation direction, and the hydraulic actuator can move in the second direction opposite to the first direction.

[0037] Furthermore, the gear pump 100 can operate in pumping mode or motoring mode. In pumping mode, the gear pump 100 provides pressurized fluid to a hydraulic actuator to drive the actuator's working member (e.g., piston) against a resistive load. In motoring mode, the fluid returning from the hydraulic actuator is a high-pressure fluid that can drive a prime mover (e.g., an electric motor) that drives the gear pump 100 in regeneration mode.

[0038] Next, the operation of the gear pump 100 will be explained assuming that the gear pump rotates in a given direction. However, it should be understood that the gear pump 100 can also operate in other directions in which the operation of the ports and fluid volume is reversed.

[0039] During operation, the prime mover (e.g., engine or electric motor) drives either the pump shaft 132 or the ring gear 130. Thus, the pump pinion 134 rotates within the ring gear 130, causing the ring gear 130 to rotate, or the ring gear 130 rotates, thereby causing the pump pinion 134 to rotate. As described above, the pump pinion 134 rotates eccentrically with respect to the ring gear 130. In other words, the longitudinal axis, which is the center of rotation of the pump pinion 134, is offset from the respective longitudinal axes, which are the centers of rotation of the ring gear 130.

[0040] When the outer teeth 135 of the pump pinion 134 and the inner teeth 131 of the ring gear 130 are separated or disengaged, they form an expanded volume (i.e., an expanded chamber). The expanded volume collectively represents a plurality of pockets formed between the separated teeth. The expanded volume functions as a suction gap formed between the teeth separating on the suction side of the gear pump 100, and this suction gap is fluid-connected to an inlet port (e.g., a first port 114). Thus, fluid from the inlet port fills the expanded volume between the teeth.

[0041] The fluid is then transported by the outer teeth 135 of the pump pinion 134 and the inner teeth 131 of the ring gear 130 to another chamber or discharge volume of the gear pump 100, which is fluid-connected to the outlet port (e.g., the second port 116). The fluid is pushed aside by the meshing of the gear teeth of the pump pinion 134 and the ring gear 130, and then supplied to the outlet port. This causes the teeth of the pump pinion 134 and the ring gear 130 to mesh on the discharge side of the gear pump 100, reducing the volume and pressurizing the fluid.

[0042] When the outer teeth 135 of the pump pinion 134 and the inner teeth 131 of the ring gear 130 mesh, these teeth form a seal between the expanded volume containing the low-pressure fluid received from the input port and the volume between the meshed or nearly meshed teeth at the outlet port. The seal formed by the meshed teeth pushes the fluid out of the discharge port and prevents the fluid from flowing back towards the inlet port.

[0043] Furthermore, as shown in Figures 2 and 3, the gear pump 100 includes a crescent-shaped seal assembly comprising an inner crescent-shaped member 162 and an upper or outer crescent-shaped member 164. The terms “inner” and “outer” refer to the radial positioning of the crescent, with the inner crescent-shaped member 162 positioned radially inward relative to the outer crescent-shaped member 164.

[0044] The inner crescent-shaped member 162 and the outer crescent-shaped member 164 are axially supported by pivot pins or positioning pins 166 within the internal space between the ring gear 130 and the pump pinion 134. Referring to Figure 2, the positioning pin 166 is partially located within a hole formed in the cylindrical projections 120, 122 and extends through the positioning pin through-holes in the thrust plates 142, 144 and through the crescent-shaped members 162, 164.

[0045] With this structure, the inner crescent-shaped member 162 and the outer crescent-shaped member 164 are held in position axially by the positioning pin 166, which also maintains the orientation of the crescent-shaped members 162 and 164. Thus, the positioning pin 166 supports the crescent-shaped seal assembly (inner crescent-shaped member 162 and outer crescent-shaped member 164) in the axial direction.

[0046] As the pump pinion 134 and ring gear 130 rotate during the operation of the gear pump 100, the crescent-shaped members 162 and 164 divide the fluid as it is transported from the low-pressure suction expansion volume to the volume connected to the discharge port. Thus, the crescent-shaped members 162 and 164 can form a seal between the low-pressure volume and the high-pressure volume.

[0047] In particular, the outer surface (i.e., the radially outward surface) of the outer crescent-shaped member 164 forms an interface with the inner teeth row 131 of the ring gear 130, forming a seal between them. The effective seal between the outer surface of the outer crescent-shaped member 164 and the inner teeth row 131 of the ring gear 130 can prevent leakage from the high-pressure volume to the low-pressure volume. In this specification, the terms “blocking” or “blocking” the fluid flow are used to mean substantially obstructing the fluid flow, for example, except for a minimum flow of droplets per minute.

[0048] Similarly, the inner surface of the inner crescent-shaped member 162 (i.e., the radially inward surface) forms an interface with the outer teeth row 135 of the pump pinion 134, forming a seal between them. The effective seal between the inner surface of the inner crescent-shaped member 162 and the outer teeth row 135 of the pump pinion 134 can prevent leakage from the high-pressure volume to the low-pressure volume.

[0049] The structure of the crescent-shaped seal assembly of crescent-shaped members 162 and 164 provides an effective seal, compensating for the radial gap between the crescent-shaped members 162 and 164 and the gear teeth to form an effective seal. In particular, fluid from an expanded or high-pressure volume penetrating through the interface between the outer crescent-shaped member 164 and the inner crescent-shaped member 162 can push the crescent-shaped members 162 and 164 radially apart. The fluid between the crescent-shaped members 162 and 164 can therefore push the outer crescent-shaped member 164 radially outward and toward the inner teeth 131 of the ring gear 130, thereby eliminating all radial space or gap between them and forming an effective seal. Similarly, the fluid between the crescent-shaped members 162 and 164 can push the inner crescent-shaped member 162 radially inward and toward the outer teeth row 135 of the pump pinion 134, thereby eliminating all radial space or gap between them and forming an effective seal.

[0050] Furthermore, in one example, the crescent-shaped members 162 and 164 can be configured such that at least one spring cavity is formed between them. The spring cavity can be formed as a recess on the inner surface of the outer crescent-shaped member 164. In another exemplary embodiment, the spring cavity can be formed as a recess on the outer surface of the inner crescent-shaped member 162. In yet another example, both the inner crescent-shaped member 162 and the outer crescent-shaped member 164 may have engaging or opposing recesses that form a spring cavity between them.

[0051] The spring cavity can house a spring (e.g., a leaf spring, a corrugated spring, or a coil spring) inside. In addition to the fluid pushing the crescent-shaped members 162 and 164 radially apart, the spring placed within the spring cavity can also push the crescent-shaped members 162 and 164 radially apart. With such a structure, the spring can push the outer crescent-shaped member 164 radially outward and toward the inner teeth row 131 of the ring gear 130, thereby improving the sealing effect between them. Similarly, the spring can push the inner crescent-shaped member 162 radially inward and toward the outer teeth row 135 of the pump pinion 134, thereby improving the sealing effect between them.

[0052] Furthermore, the crescent-shaped seal assembly may have a check valve between the crescent-shaped members 162 and 164 to prevent fluid flow from the high-pressure volume to the low-pressure volume, regardless of the rotational direction of the pump shaft 132. In particular, the outer crescent-shaped member 164 and the inner crescent-shaped member 162 may have a recess or groove between them that forms a check valve cavity or recess. A check pin may be positioned within such a check valve cavity.

[0053] The pressurized fluid, permeating from the high-pressure volume to the low-pressure volume between the crescent-shaped members 162 and 164, presses the check pin against the inner surfaces of the crescent-shaped members 162 and 164, forming a seat for the check pin. Thus, the check pin, together with the surface of the crescent-shaped members, forms a seal, preventing leakage through it. If the pump shaft 132 rotates in a different direction, another check pin and check valve cavity located on the opposite side can prevent or block leakage in the other direction.

[0054] Therefore, this structure of the crescent-shaped seal assembly allows the gear pump 100 to be bidirectional. Depending on whether the fluid is drawn in through the first port 114 and then moves to the second port 116, or vice versa, the check pin acts as a reverse check valve, blocking the leakage fluid flow in either direction. Additional check pins can be added to further improve the seal between the suction and discharge sides of the gear pump 100.

[0055] As shown in Figure 4 and described above, the fluid passages 154-160 and fluid cavities 146-152 of the thrust plates 142 and 144 facilitate fluid communication from the expanded and high-pressure volumes formed between the pump pinion 134 and the ring gear 130 in both axial directions, causing the fluid to reach the interface between the thrust plates 142 and 144 and the cylindrical projections 120 and 122. The fluid trapped at the interface between the thrust plate 142 and the cylindrical projection 120 applies an axial fluid force to the thrust plate 142, directing it toward the end faces of the pump pinion 134 and the ring gear 130. In this way, a metal-to-metal seal is formed between the thrust plate 142 and the end faces of the pump pinion 134 and the ring gear 130.

[0056] Similarly, fluid trapped at the interface between the thrust plate 144 and the cylindrical projection 122 applies an axial fluid force to the thrust plate 144, directing it toward the other end faces of the pump pinion 134 and the ring gear 130. In this way, a metal-to-metal seal is formed between the thrust plate 144 and the end faces of the pump pinion 134 and the ring gear 130.

[0057] The fluid force acting on the thrust plates 142,144 toward the pump pinion 134 and ring gear 130 pushes or compresses the thrust plates 142,144 axially against the pump pinion 134 and ring gear 130, thereby forming an effective seal and eliminating all axial gaps between them. Thus, the thrust plates 142,144 can compensate for all axial gaps between the thrust plates 142,144 and the pump pinion 134 and ring gear 130 positioned between them, thereby reducing leakage and increasing the efficiency of the gear pump 100, and can therefore be called axial compensators.

[0058] As described above, on the suction side of the gear pump 100, when the outer teeth 135 of the pump pinion 134 separate from the inner teeth 131 of the ring gear 130, a low-pressure expanded volume is formed. On the discharge side of the gear pump 100, when the outer teeth 135 of the pump pinion 134 mesh with the inner teeth 131 of the ring gear 130, the fluid is discharged under pressure due to the reduced volume. Such pressurized fluid between the pump pinion 134 and the ring gear 130 on the discharge side can apply a radially outward force to the ring gear 130 and the drive flange 128, directing it toward the cylindrical projections 120 and 122. As a result, friction and wear may occur at the interface between the drive flange 128 and the cylindrical projections 120 and 122 in the region where the radially outward force pushes the drive flange 128 radially toward the cylindrical projections 120 and 122.

[0059] Such interface regions may differ based on the rotation direction of the pump pinion 134 and the ring gear 130. In particular, regions prone to wear or friction when the pump pinion 134 and the ring gear 130 are rotating in a first direction (for example, when the first port 114 is the inlet port and the second port 116 is the outlet port) may differ from the respective regions prone to wear or friction when the pump pinion 134 and the ring gear 130 are rotating in a second direction (for example, when the second port 116 is the inlet port and the first port 114 is the outlet port).

[0060] As shown in Figure 4, the cylindrical projection 120 has cross holes such as cross holes 168 and 170. The term “cross hole” refers to a hole that crosses the path of another hole, cavity, or passage. The cross holes 168 and 170 are configured to communicate fluid from the first fluid cavity 146 and the second fluid cavity 148 to the interface between the first outer bush 124 and the cylindrical projection 120, respectively. Thus, the cross holes 168 and 170 can communicate high-pressure fluid in the first fluid cavity 146 or the second fluid cavity 148 to the interface between the first outer bush 124 and the cylindrical projection 120 (depending on the rotation direction of the ring gear 130 and the pump pinion 134) in order to support the first outer bush 124 during the rotation of the drive flange 128.

[0061] Similarly, the cylindrical projection 122 has cross holes such as cross holes 172 and 174. The cross holes 172 and 174 are configured to communicate fluid from the first fluid cavity 150 and the second fluid cavity 152 to the interface between the second outer bush 126 and the cylindrical projection 122, respectively. Thus, the cross holes 172 and 174 can communicate high-pressure fluid in the first fluid cavity 150 or the second fluid cavity 152 to the interface between the second outer bush 126 and the cylindrical projection 122 (depending on the rotation direction of the ring gear 130 and the pump pinion 134) in order to support the second outer bush 126 during rotation of the drive flange 128.

[0062] The cross holes 168-174 supply fluid to the hydrostatic fluid mechanism, as will be described later, and may therefore be called supply ports.

[0063] Figure 5 shows a perspective view of the first end cover 104 according to an exemplary embodiment. Figure 5 shows the cylindrical projection 120 without the first outer bushing 124.

[0064] As shown in Figure 5, the cylindrical projection 120 has a first hydrostatic fluid groove 176 and a second hydrostatic fluid groove 178. The first hydrostatic fluid groove 176 is a circumferential groove extending over a specific angular range around the outer surface of the cylindrical projection 120. Similarly, the second hydrostatic fluid groove 178 is a circumferential groove extending over an angular range around the outer surface of the cylindrical projection 120. The first hydrostatic fluid groove 176 overlaps the second hydrostatic fluid groove 178 with respect to a portion of the respective angular ranges of hydrostatic fluid grooves 176 and 178. However, the first hydrostatic fluid groove 176 is not fluid-connected to the second hydrostatic fluid groove 178, and since these grooves receive fluid at different pressure levels, no cross-flow occurs between them.

[0065] Referring to Figures 4 and 5, the cross holes 168 and 170 communicate fluid to the interface between the first outer bushing 124 and the cylindrical projection 120, and thus such fluid fills the hydrostatic fluid grooves 176 and 178, thereby supporting the first outer bushing 124 during rotation of the drive flange 128. In particular, the cross hole 170 communicates fluid from the second fluid cavity 148 to the first hydrostatic fluid groove 176, while the cross hole 168 communicates fluid from the first fluid cavity 146 to the second hydrostatic fluid groove 178.

[0066] Figure 6 shows a perspective view of the first end cover 104 together with a first outer bushing 124 attached to the cylindrical projection 120, according to an exemplary embodiment. As shown, the first outer bushing 124 has a first hydrostatic fluid slit 180 (e.g., an opening or window) and a second hydrostatic fluid slit 182.

[0067] The first hydrostatic fluid slit 180 is positioned around the surface of the first outer bush 124 at an angular distance from the second hydrostatic fluid slit 182. Furthermore, the first hydrostatic fluid slit 180 is fluidly connected to the first hydrostatic fluid groove 176 of the cylindrical projection 120, and the second hydrostatic fluid slit 182 is fluidly connected to the second hydrostatic fluid groove 178 of the cylindrical projection 120.

[0068] Figure 7 shows a partially sectioned perspective view of the first end cover 104 according to an exemplary embodiment. In Figure 7, it is assumed that the gear pump 100 is operating in a mode in which high-pressure fluid is supplied to the second fluid cavity 148, while low-pressure fluid is supplied to the first fluid cavity 146.

[0069] As shown in Figure 7, the high-pressure (outlet) fluid communicates from the second fluid cavity 148 through the cross hole 170 to the first hydrostatic fluid groove 176, and then through the first hydrostatic fluid slit 180 to the interface between the drive flange 128 and the first outer bush 124. This provides pressurized fluid to a region of the first outer bush 124 where a minimum gap can be created between the first outer bush 124 and the drive flange 128. Such use of high-pressure fluid in such a minimum gap region can reduce friction / wear when supporting the rotation of the drive flange 128 against the cylindrical projection 120, especially at low rotational speeds, enhance the capacity of the first outer bush 124 under bearing load, and improve the lubrication and performance of the first outer bush 124.

[0070] Similarly, referring to Figures 4 to 7, the low-pressure (inlet) fluid communicates from the first fluid cavity 146 through the cross hole 168 to the second hydrostatic fluid groove 178, and then through the two hydrostatic fluid slits 182 to the interface between the drive flange 128 and the first outer bush 124. Such low-pressure fluid can further assist in lubrication at the interface between the first outer bush 124 and the drive flange 128, and can also provide a cooling effect (for example, at the lubricated interface).

[0071] In particular, as described above, the gear pump 100 is configured to be bidirectional. Therefore, in another operating mode in which the ring gear 130 and pump pinion 134 rotate in opposite directions, the first fluid cavity 146 can receive high-pressure fluid, thereby allowing the second hydrostatic fluid slit 182 to communicate with such high-pressure fluid in the region with the smallest gap. In this mode, the second fluid cavity 148 receives low-pressure fluid and communicates it with the first hydrostatic fluid slit 180. In other words, the high-pressure and low-pressure fluids in Figure 7 are switched.

[0072] The cylindrical projection 122 and the second outer bushing 126 are similarly configured to assist lubrication, reduce friction / wear between the drive flange 128 and the cylindrical projection 122, and enhance the capacity of the second outer bushing 126 under bearing load.

[0073] Figure 8 shows a perspective view of the cylindrical projection 122 and the second outer bushing 126 in the first operating mode according to an exemplary embodiment. Similar to the first outer bushing 124, the second outer bushing 126 has hydrostatic fluid slits 184 and 186, which are in fluid communication with hydrostatic fluid grooves (not shown) formed in the cylindrical projection 122.

[0074] In one operating mode in which the pump shaft 132, pump pinion 134, and ring gear 130 rotate in one direction, the first fluid cavity 150 receives the high-pressure fluid from the gear pump 100, and the fluid is communicated from the first fluid cavity 150 through the hydrostatic fluid slit 186 to a region 188 (shown in shadow) that represents the smallest gap region in this operating mode (for example, the smallest gap between the second outer bush 126 and the drive flange 128). This region 188 either overlaps with or surrounds the hydrostatic fluid slit 186, as shown in Figure 8.

[0075] In the other operating mode, in which the pump shaft 132, pump pinion 134, and ring gear 130 rotate in opposite directions, the second fluid cavity 152 receives high-pressure fluid. This high-pressure fluid is then communicated to the respective smallest gap regions through the hydrostatic fluid slits 184.

[0076] Figure 9 shows a perspective view of the cylindrical projection 122 and the second outer bushing 126 in a second operating mode according to an exemplary embodiment. As shown in Figure 9, in this operating mode, the second fluid cavity 152 receives the high-pressure fluid from the gear pump 100, and the fluid is communicated from the second fluid cavity 152 through the hydrostatic fluid slit 184 to a region 190 (shown in shade) that represents the minimum gap region in this operating mode (e.g., the minimum gap between the second outer bushing 126 and the drive flange 128). This region 190 either overlaps with or surrounds the hydrostatic fluid slit 184, as shown in Figure 9.

[0077] The fluid communicates with the interface between the outer bushings 124, 126, which have cylindrical projections 120, 122, and the drive flange 128, while simultaneously communicating with the interface between the inner bushings 136, 138 and the inner circumferential surfaces of the cylindrical projections 120, 122. In particular, the internal cavities or through holes of the cylindrical projections 120, 122, which house the pump shaft 132 and the inner bushings 136, 138, are defined by surfaces having hydrostatic fluid grooves similar to those of hydrostatic fluid grooves 176, 178.

[0078] The inner bushings 136 and 138 may also have hydrostatic fluid slits similar to those 180-186, configured to diffuse fluid at the interface between the inner bushings 136 and 138 and the cylindrical projections 120 and 122, in order to promote and support the rotation of the pump shaft 132. In this way, the rotation of the pump shaft 132 is supported and lubricated, especially at low rotational speeds, thereby improving performance, reducing friction / wear, and enhancing the capacity of the inner bushings 136 and 138 under bearing load.

[0079] Figure 10 shows a perspective view of the second end cover 106 according to an exemplary embodiment. As shown in Figure 10, the second inner bush 138 may have a hydrostatic fluid slit 192 and a hydrostatic fluid slit 194. In Figure 10, the second fluid cavity 152 receives the high-pressure (outlet) fluid, and this second fluid cavity communicates with the hydrostatic fluid slit 184 of the outer bush 126, as described above.

[0080] Simultaneously, pressurized fluid from the second fluid cavity 152 is communicated to the hydrostatic fluid slit 192 on the opposite side, and the fluid then diffuses through the hydrostatic fluid slit 192 to the interface between the second inner bush 138 and the inner surface of the cylindrical projection. That is, the low-pressure fluid in the first fluid cavity 150 is communicated to the hydrostatic fluid slit 194 through the cross hole 196 and the hydrostatic fluid groove 198 formed on the inner surface of the cylindrical projection 122.

[0081] The first inner bushing 136 and the cylindrical projection 120 may have similar structures. In this way, the rotation of the pump shaft 132 is supported and lubricated during the operation of the gear pump 100.

[0082] In one example, the gear pump 100 can be driven via a prime mover outside the gear pump 100. For example, referring to Figures 2 to 4, an engine or electric motor can be connected to the pump shaft 132 via a spline 199 formed at the end of the pump shaft 132. However, in another example, an electric motor can be incorporated into an internal chamber 103 of the assembly housing 102 to drive the gear pump 100. Such a structure forms a compact assembly including the prime mover (electric motor) and the gear pump 100.

[0083] Figure 11 shows a side section view of an assembly 200, which includes a gear pump 100 and an electric motor 202 integrated with the gear pump, according to an exemplary embodiment, and Figure 12 shows an exploded perspective view of the assembly 200. Figures 11 and 12 will be described together. As shown, the electric motor 202 is located in an internal chamber 103 of the assembly housing 102.

[0084] The electric motor 202 includes a stator 204 fixedly positioned within an internal chamber 103 of the assembly housing 102. The stator 204 may have wire windings 206 wound around the body of the stator 204 (e.g., a stacked stack), and when current is supplied through these wire windings, a magnetic field is generated.

[0085] The electric motor 202 further includes a rotor 208 positioned within a stator 204. The electric motor 202 may further include magnets 210 mounted on the rotor 208 within an annular space between the stator 204 and the rotor 208. The magnets 210 are configured to interact with the magnetic field generated by the wire windings 206 of the stator 204 to rotate the rotor 208 and generate torque. In other exemplary embodiments, different types of electric motors that do not include permanent magnets may be used.

[0086] The gear pump 100 is mounted within an assembly housing 102 and at least partially within the rotor 208 and stator 204 of the electric motor 202. Furthermore, the rotor 208 is coupled to a drive flange 128 such that the drive flange 128 and ring gear 130 rotate with the rotor as the rotor 208 rotates. For example, the drive flange 128 may be press-fitted into the rotor 208 so that the drive flange 128 is coupled to the rotor 208. Alternatively, other devices such as keyway devices, spline devices, self-holding taper devices, etc., may be used to couple the rotor 208 to the drive flange 128.

[0087] Therefore, as the rotor 208 rotates, the drive flange 128 and ring gear 130 rotate, thereby driving the pump pinion 134, which is attached to or integrated with the pump shaft 212. The pump shaft 212 differs from the pump shaft 132 in that it is shorter and does not extend outside the first end cover 104. The pump shaft 212 is driven not by an external prime mover, but rather by an electric motor 202 integrated with the gear pump 100 in the assembly 200. A plug 214 can be used to cover the hole in the first end cover 104 into which the pump shaft 212 can be inserted.

[0088] When the rotor 208 drives the ring gear 130, the ring gear 130 drives the pump pinion 134, which is offset from the ring gear 130 as described above (i.e., the pump pinion 134 is eccentrically positioned relative to the ring gear 130). A separate bearing to support the rotation of the rotor 208 can be eliminated. Rather, the outer bushings 124, 126 and the inner bushings 136, 138 support the rotation of the rotating components of the assembly 200. This allows the gear pump 100 and the electric motor 202 to share components, thereby reducing costs and resulting in a compact assembly.

[0089] The above detailed description illustrates various features and operations of the disclosed system with reference to the accompanying drawings. The exemplary embodiments described herein are not intended to be limiting. Certain aspects of the disclosed system can be arranged and combined in a wide variety of different structures, all of which are assumed herein.

[0090] Furthermore, unless otherwise suggested by the context, the features shown in each figure may be used in combination with each other. Therefore, the drawings should generally be referred to as embodiments of one or more of all embodiments, and it should be understood that not all illustrated features are required for each embodiment.

[0091] Furthermore, any enumeration of elements, blocks, or steps in this specification or in the claims is for clarification purposes only. Therefore, such enumeration should not be construed as requiring or suggesting that these elements, blocks, or steps must be performed in a particular arrangement or order.

[0092] Furthermore, the device or system may be used or configured to perform the functions shown in the drawings. In some cases, the components of the device and / or system may be configured (using hardware and / or software) to perform the function in such a way that these components are actually configured and built to enable such performance. In other examples, the components of the device and / or system may be adapted to perform the function, be able to perform the function, or be arranged to perform the function in a particular way, for example.

[0093] The term "substantially" means that the listed characteristics, parameters, or values ​​do not necessarily have to be achieved exactly, but deviations or variations may occur, including, for example, tolerances, measurement errors, limits of measurement accuracy, and other factors known to those skilled in the art, to the extent that they do not hinder the effect that the feature is intended to provide.

[0094] The apparatus described herein is for illustrative purposes only. Therefore, as will be obvious to those skilled in the art, other apparatuses and elements (e.g., machines, interfaces, operations, sequences, and groupings of operations) can be used instead, and some elements can be omitted entirely depending on the desired result. Furthermore, many of the elements described are functional entities that can be implemented as discrete or distributed components, or in cooperation with other components in any suitable combination and location.

[0095] While various aspects and embodiments are disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are illustrative and not intended to limit, and the true scope, along with the entire scope of the equivalents to which the appended claims are entitled, is indicated by the following claims. Furthermore, the terms used herein are intended solely to describe specific embodiments and are not intended to limit them.

[0096] Therefore, embodiments of this disclosure may relate to one of the listed exemplary embodiments (EEEs) below.

[0097] EEE1 is a gear pump having a pump housing with a hydrostatic fluid groove; an outer bushing attached to the pump housing and having a hydrostatic fluid slit that is fluidly connected to the hydrostatic fluid groove of the pump housing; a drive flange, the drive flange attached to the outer bushing so that the outer bushing is inserted radially between the pump housing and the drive flange; a ring gear connected to the drive flange and configured to rotate with the drive flange; a pump pinion, the pump pinion positioned within the ring gear such that its outer teeth engage with the inner teeth of the ring gear; and a plurality of ports, including a first port and a second port, wherein as the pump pinion and the ring gear rotate, fluid is drawn in from the first port and moved to the second port for discharge, and the fluid from the second port is supplied to the hydrostatic fluid groove of the pump housing and communicates with the interface between the drive flange and the outer bushing through the hydrostatic fluid slit, thereby facilitating the rotation of the drive flange relative to the pump housing.

[0098] EEE2 is a gear pump according to EEE1, wherein the hydrostatic fluid groove is a first hydrostatic fluid groove, the hydrostatic fluid slit is a first hydrostatic fluid slit, the pump housing comprises a second hydrostatic fluid groove, the outer bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the interface between the drive flange and the outer bush through the second hydrostatic fluid slit.

[0099] EEE3 is the gear pump described in EEE2, wherein the first hydrostatic fluid slit is positioned around the surface of the outer bush at an angular distance from the second hydrostatic fluid slit.

[0100] EEE4 is a gear pump according to EEE2 or 3, wherein the first hydrostatic fluid groove is a circumferential groove extending over a specific angular range around the outer surface of the pump housing, and the second hydrostatic fluid grooves are circumferential grooves extending over their respective angular ranges around the outer surface of the pump housing, and the first hydrostatic fluid groove overlaps the second hydrostatic fluid groove in part of their respective angular ranges.

[0101] EEE5 is a gear pump according to any one of EEE1 to 4, wherein the pump housing has a cylindrical projection with a hydrostatic fluid groove, and an outer bush is attached to the cylindrical projection.

[0102] EEE6 is the gear pump according to EEE5, wherein the cylindrical projection is a first cylindrical projection, and the pump housing has a second cylindrical projection facing the first cylindrical projection, so that the ring gear and pump pinion are inserted between the first cylindrical projection and the second cylindrical projection.

[0103] EEE7 is the gear pump according to EEE6, wherein the outer bush is a first outer bush attached to a first cylindrical projection, the second cylindrical projection having respective hydrostatic fluid grooves, and the gear pump further has a second outer bush attached to the second cylindrical projection and inserted radially between the second cylindrical projection and the drive flange, the second outer bush having respective hydrostatic fluid slits that are fluidly connected to the respective hydrostatic fluid grooves of the second cylindrical projection, thereby supplying fluid from the second port to the respective hydrostatic fluid grooves of the second cylindrical projection and communicating through the respective hydrostatic fluid slits to the respective interface between the drive flange and the second outer bush to facilitate rotation of the drive flange relative to the pump housing.

[0104] EEE8 is a gear pump according to EEE6 or 7, comprising a first end cover having a first cylindrical projection; and a second end cover having a second cylindrical projection, the second end cover further comprising a second end cover having a first port and a second port.

[0105] EEE9 is a gear pump according to any one of EEE5 to 8, wherein the cylindrical projection has (i) a fluid cavity fluid-connected to a second port, and (ii) a cross hole configured to allow fluid from the fluid cavity to communicate with a hydrostatic fluid groove.

[0106] EEE10 is a gear pump according to any one of EEE1 to 9, wherein a pump pinion is mounted on a pump shaft, the pump shaft is supported within a pump housing, and the gear pump is mounted within the pump housing and further has an inner bush inserted radially between the pump shaft and the inner surface of the pump housing, the inner surface of the pump housing having respective hydrostatic fluid grooves, the inner bush having respective hydrostatic fluid slits which are fluid-connected to each hydrostatic fluid groove, and fluid from a second port is supplied to each hydrostatic fluid groove and communicates through each hydrostatic fluid slit to the respective interface between the inner bush and the inner surface of the pump housing to facilitate rotation of the pump shaft relative to the pump housing.

[0107] EEE11 is a gear pump according to EEE10, wherein each hydrostatic fluid groove is a first hydrostatic fluid groove, each hydrostatic fluid slit is a first hydrostatic fluid slit, the pump housing comprises a second hydrostatic fluid groove formed on the inner surface of the pump housing, the inner bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the respective interface between the inner bush and the inner surface of the pump housing through the second hydrostatic fluid slit.

[0108] EEE12 is a gear pump as described in EEE11, wherein the rotation centers of the pump shaft and pump pinion are offset from the respective rotation centers of the ring gear such that the inner bushing is eccentric with respect to the outer bushing.

[0109] EEE13 is an assembly comprising: an assembly housing having an internal chamber inside; an electric motor disposed in the internal chamber of the assembly housing, having (i) a stator fixedly positioned in the internal chamber of the assembly housing, and (ii) a rotor located inside the stator and rotatable relative to the stator; and a gear pump according to any one of EEE1 to 12, located within the assembly housing and at least partially located within the rotor of the electric motor. For example, a gear pump has a drive flange connected to the rotor of an electric motor such that the rotor is configured to rotate the drive flange, a ring gear connected to the drive flange and configured to rotate with the drive flange, a pump pinion positioned within the ring gear such that the outer teeth of the pump pinion engage with the inner teeth of the ring gear, and a plurality of ports including a first port and a second port, wherein when the rotor rotates, the drive flange and the ring gear rotate with the rotor, thereby rotating the pump pinion within the ring gear, thereby drawing fluid in from the first port and moving it to the second port for discharge.

[0110] EEE14 is an assembly according to EEE13, comprising an end cover connected to an assembly housing, having a cylindrical projection, the cylindrical projection having a hydrostatic fluid groove; and an outer bushing attached to the cylindrical projection so as to be inserted radially between the cylindrical projection and the drive flange, the outer bushing having a hydrostatic fluid slit that is fluidly connected to the hydrostatic fluid groove of the cylindrical projection, and fluid from a second port is supplied to the hydrostatic fluid groove of the cylindrical projection and communicates through the hydrostatic fluid slit to the interface between the drive flange and the outer bushing to facilitate rotation of the drive flange relative to the cylindrical projection.

[0111] EEE15 is the assembly according to EEE14, wherein the hydrostatic fluid groove is a first hydrostatic fluid groove, the hydrostatic fluid slit is a first hydrostatic fluid slit, the cylindrical projection comprises a second hydrostatic fluid groove, the outer bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the interface between the drive flange and the outer bush through the second hydrostatic fluid slit.

[0112] EEE16 is the assembly according to EEE14 or 15, wherein the end cover is a first end cover, the cylindrical projection is a first cylindrical projection, and the assembly further has a second end cover connected to the assembly housing and having a second cylindrical projection facing the first cylindrical projection, and the ring gear and pump pinion are inserted between the first cylindrical projection and the second cylindrical projection.

[0113] EEE17 is the assembly according to EEE16, wherein the outer bush is a first outer bush attached to a first cylindrical projection, the second cylindrical projection having respective hydrostatic fluid grooves, and the gear pump further has a second outer bush attached to the second cylindrical projection and inserted radially between the second cylindrical projection and the drive flange, the second outer bush having respective hydrostatic fluid slits that are fluidly connected to the respective hydrostatic fluid grooves of the second cylindrical projection, thereby supplying fluid from the second port to the respective hydrostatic fluid grooves of the second cylindrical projection and communicating through the respective hydrostatic fluid slits to the respective interface between the drive flange and the second outer bush to facilitate rotation of the drive flange relative to the second cylindrical projection.

[0114] EEE18 is an assembly according to any one of EEE14 to 17, wherein the cylindrical projection has (i) a fluid cavity fluid-connected to a second port, and (ii) a cross hole configured to allow fluid from the fluid cavity to communicate with a hydrostatic fluid groove.

[0115] EEE19 is an assembly according to any one of EEE14 to 18, wherein a pump pinion is mounted on a pump shaft, the pump shaft is supported within a cylindrical projection, and a gear pump is mounted within the cylindrical projection and further has an inner bushing inserted radially between the pump shaft and the inner surface of the cylindrical projection, the inner surface of the cylindrical projection having respective hydrostatic fluid grooves, and the inner bushing having respective hydrostatic fluid slits to which fluid is fluidly connected to each hydrostatic fluid groove, and fluid from a second port is supplied to each hydrostatic fluid groove and communicates through each hydrostatic fluid slit to the respective interface between the inner bushing and the inner surface of the cylindrical projection to facilitate rotation of the pump shaft relative to the cylindrical projection.

[0116] EEE20 is the assembly according to EEE19, wherein each hydrostatic fluid groove is a first hydrostatic fluid groove, each hydrostatic fluid slit is a first hydrostatic fluid slit, each cylindrical projection has a second hydrostatic fluid groove formed on the inner surface of the cylindrical projection, each inner bush has a second hydrostatic fluid slit, and fluid from the first port is supplied to each second hydrostatic fluid groove and communicates with each interface between the inner bush and the inner surface of the cylindrical projection through each second hydrostatic fluid slit.

Claims

1. It is a gear pump, Pump housing with hydrostatic fluid grooves; An outer bushing attached to the pump housing and having a hydrostatic fluid slit that is fluidly connected to the hydrostatic fluid groove of the pump housing; A drive flange, wherein the outer bushing is attached to the outer bushing so as to be inserted radially between the pump housing and the drive flange; A ring gear connected to the drive flange and configured to rotate together with the drive flange; A pump pinion, wherein the outer teeth of the pump pinion are positioned within the ring gear such that they engage with the inner teeth of the ring gear; and A plurality of ports, including a first port and a second port, wherein when the pump pinion and the ring gear rotate, fluid is drawn in from the first port and moved to the second port for discharge, and the fluid from the second port is supplied to the hydrostatic fluid groove of the pump housing and communicates with the interface between the drive flange and the outer bush through the hydrostatic fluid slit, thereby facilitating the rotation of the drive flange relative to the pump housing. A gear pump that has [this feature].

2. The gear pump according to claim 1, wherein the hydrostatic fluid groove is a first hydrostatic fluid groove, the hydrostatic fluid slit is a first hydrostatic fluid slit, the pump housing comprises a second hydrostatic fluid groove, the outer bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the interface between the drive flange and the outer bush through the second hydrostatic fluid slit.

3. The gear pump according to claim 2, wherein the first hydrostatic fluid slit is positioned around the surface of the outer bush at an angular distance from the second hydrostatic fluid slit.

4. The gear pump according to claim 2, wherein the first hydrostatic fluid groove is a circumferential groove extending over a specific angular range around the outer surface of the pump housing, and the second hydrostatic fluid grooves are circumferential grooves extending over their respective angular ranges around the outer surface of the pump housing, and the first hydrostatic fluid groove overlaps the second hydrostatic fluid groove in a portion of their respective angular ranges.

5. The gear pump according to claim 1, wherein the pump housing has a cylindrical projection having the hydrostatic fluid groove, and the outer bush is attached to the cylindrical projection.

6. The gear pump according to claim 5, wherein the cylindrical projection is a first cylindrical projection, and the pump housing has a second cylindrical projection facing the first cylindrical projection, so that the ring gear and the pump pinion are inserted between the first cylindrical projection and the second cylindrical projection.

7. The outer bush is a first outer bush attached to the first cylindrical projection, and the second cylindrical projection is provided with a hydrostatic fluid groove. The gear pump is attached to the second cylindrical projection and further has a second outer bushing that is inserted radially between the second cylindrical projection and the drive flange, the second outer bushing having respective hydrostatic fluid slits that are fluid-connected to the respective hydrostatic fluid grooves of the second cylindrical projection, thereby supplying fluid from the second port to the respective hydrostatic fluid grooves of the second cylindrical projection and communicating through the respective hydrostatic fluid slits to the respective interface between the drive flange and the second outer bushing, thereby promoting the rotation of the drive flange relative to the pump housing. The gear pump according to claim 6.

8. A first end cover having the first cylindrical projection; and A second end cover comprising the second cylindrical projection and the first port and the second port. The gear pump according to claim 6, further comprising the above.

9. The gear pump according to claim 5, wherein the cylindrical projection has (i) a fluid cavity fluidly connected to the second port, and (ii) a cross hole configured to allow fluid from the fluid cavity to communicate with the hydrostatic fluid groove.

10. The pump pinion is attached to the pump shaft, and the pump shaft is supported within the pump housing. The gear pump is mounted within the pump housing and further has an inner bushing inserted radially between the pump shaft and the inner surface of the pump housing, the inner surface of the pump housing having respective hydrostatic fluid grooves, the inner bushing having respective hydrostatic fluid slits that are fluid-connected to the respective hydrostatic fluid grooves, and fluid from the second port is supplied to the respective hydrostatic fluid grooves and communicates through the respective hydrostatic fluid slits to the respective interface between the inner bushing and the inner surface of the pump housing to promote rotation of the pump shaft relative to the pump housing. The gear pump according to claim 1.

11. The gear pump according to claim 10, wherein each of the aforementioned hydrostatic fluid grooves is a first hydrostatic fluid groove, each of the aforementioned hydrostatic fluid slits is a first hydrostatic fluid slit, the pump housing comprises a second hydrostatic fluid groove formed on the inner surface of the pump housing, the inner bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the respective interface between the inner bush and the inner surface of the pump housing through the second hydrostatic fluid slit.

12. The gear pump according to claim 11, wherein the rotation centers of the pump shaft and the pump pinion are offset from the respective rotation centers of the ring gear such that the inner bushing is eccentric with respect to the outer bushing.

13. It is an assembly, Assembly housing having an internal chamber; An electric motor disposed in the internal chamber of the assembly housing, the electric motor having (i) a stator fixedly positioned in the internal chamber of the assembly housing, and (ii) a rotor located inside the stator and rotatable relative to the stator; and The system has a gear pump that is positioned within the assembly housing and at least partially positioned within the rotor of the electric motor, The gear pump described above is The rotor is configured to rotate the drive flange, and the drive flange is connected to the rotor of the electric motor, A ring gear connected to the drive flange and configured to rotate together with the drive flange, A pump pinion, wherein the outer teeth of the pump pinion are arranged within the ring gear such that they engage with the inner teeth of the ring gear, A plurality of ports, including a first port and a second port, wherein when the rotor rotates, the drive flange and the ring gear rotate together with the rotor, thereby rotating the pump pinion within the ring gear, and as a result, fluid is drawn in from the first port and moved to the second port for discharge. An assembly that has

14. An end cover connected to the assembly housing and having a cylindrical projection with a hydrostatic fluid groove; and An outer bushing attached to the cylindrical projection so as to be inserted radially between the cylindrical projection and the drive flange, the outer bushing having a hydrostatic fluid slit that is fluidly connected to the hydrostatic fluid groove of the cylindrical projection, the fluid from the second port being supplied to the hydrostatic fluid groove of the cylindrical projection and communicating through the hydrostatic fluid slit to the interface between the drive flange and the outer bushing, thereby promoting the rotation of the drive flange relative to the cylindrical projection. The assembly according to claim 13, further comprising:

15. The assembly according to claim 14, wherein the hydrostatic fluid groove is a first hydrostatic fluid groove, the hydrostatic fluid slit is a first hydrostatic fluid slit, the cylindrical projection includes a second hydrostatic fluid groove, the outer bush includes a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the interface between the drive flange and the outer bush through the second hydrostatic fluid slit.

16. The end cover is a first end cover, and the cylindrical projection is a first cylindrical projection, The assembly further has a second end cover connected to the assembly housing, which has a second cylindrical projection facing the first cylindrical projection, and the ring gear and the pump pinion are inserted between the first cylindrical projection and the second cylindrical projection. The assembly according to claim 14.

17. The outer bush is a first outer bush attached to the first cylindrical projection, and the second cylindrical projection is provided with a hydrostatic fluid groove. The gear pump is attached to the second cylindrical projection and further has a second outer bushing that is inserted radially between the second cylindrical projection and the drive flange, the second outer bushing having a hydrostatic fluid slit that is fluidly connected to the respective hydrostatic fluid grooves of the second cylindrical projection, thereby supplying fluid from the second port to the respective hydrostatic fluid grooves of the second cylindrical projection and communicating through the respective hydrostatic fluid slits to the respective interface between the drive flange and the second outer bushing, thereby promoting the rotation of the drive flange relative to the second cylindrical projection. The assembly according to claim 16.

18. The assembly according to claim 14, wherein the cylindrical projection has (i) a fluid cavity fluidly connected to the second port, and (ii) a cross hole configured to allow fluid from the fluid cavity to communicate with the hydrostatic fluid groove.

19. The pump pinion is attached to the pump shaft, and the pump shaft is supported within the cylindrical projection. The gear pump is mounted within the cylindrical projection and further has an inner bushing inserted radially between the pump shaft and the inner surface of the cylindrical projection, the inner surface of the cylindrical projection having respective hydrostatic fluid grooves, and the inner bushing having respective hydrostatic fluid slits that are fluid-connected to the respective hydrostatic fluid grooves, the fluid from the second port being supplied to the respective hydrostatic fluid grooves and communicating through the respective hydrostatic fluid slits to the respective interface between the inner bushing and the inner surface of the cylindrical projection, thereby promoting the rotation of the pump shaft relative to the cylindrical projection. The assembly according to claim 14.

20. The assembly according to claim 19, wherein each of the aforementioned hydrostatic fluid grooves is a first hydrostatic fluid groove, each of the aforementioned hydrostatic fluid slits is a first hydrostatic fluid slit, the cylindrical projection comprises a second hydrostatic fluid groove formed on the inner surface of the cylindrical projection, the inner bush comprises a second hydrostatic fluid slit, and fluid from the first port is supplied to the second hydrostatic fluid groove and communicates with the respective interface between the inner bush and the inner surface of the cylindrical projection through the second hydrostatic fluid slit.

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