Assembly for hydraulic gear pump with force balance and internal cooling features

Abstract

An example of a gear pump includes a pump housing having a pump housing channel and an arcuate groove disposed within an inner surface of the pump housing, a pump internal gear disposed within the pump housing and rotatable relative to the pump housing, a pump pinion disposed within the pump internal gear such that its teeth engage with the internal teeth of the pump internal gear, and a pump port block having a first port and a second port, wherein as the pump pinion rotates within the pump internal gear, fluid is drawn through the first port and provided to the second port for discharge, a portion of the fluid provided to the second port is provided to the pump housing channel, and fluid obtained from the pump housing channel is provided to the arcuate groove to apply a radially inward force to the pump internal gear.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 182,072, filed April 30, 2021, the entirety of which is incorporated herein by reference. [Background technology]

[0002] Gear pumps use gear meshing that pumps fluid by a displacement. There are two main variations: external gear pumps, which use two external spur gears, and internal gear pumps, which use an external (e.g., pinion) spur gear and an internal (e.g., ring) spur gear. Gear pumps have a fixed displacement that allows them to provide a constant amount of fluid with each revolution of the pump.

[0003] As the pump gears rotate, the gear teeth separate at the intake side of the pump, creating a void and suction that is then filled with fluid. The fluid is conveyed by the gears to the discharge or outlet side of the pump where the gear meshes displace the fluid under pressure. In some cases, high pressure fluid at the outlet side of the pump can push the internal gears of an internal gear pump towards the pump housing, increasing the chance of wear due to friction. As a result, it may be desirable to neutralize the force that the high pressure fluid exerts on the gears to reduce wear.

[0004] Additionally, during operation of the pump, the pump housing may heat up, and as a result, it may be desirable to cool the pump housing to alleviate any problems caused by overheating the pump housing.

[0005] An electric motor can be used to drive a pump. For example, a rotor of the electric motor can be coupled to a shaft of the pump, such that rotation of the rotor can turn a rotating group of the pump to provide fluid flow.

[0006] The electronic drive, including the inverter and motor controller, is typically separate from the motor and is connected to the stator windings of the electric motor via cables. It may be desirable to have an assembly that integrates the pump and the electronic drive with the electric motor. In this way, mechanical components such as shafts, bearings, etc. can be shared between the hydraulic pump and the motor, and cables running between the controller and the motor can be eliminated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Provisional Patent Application No. 63 / 182,072 Summary of the Invention [Problem to be solved by the invention]

[0008] It is with respect to these and other considerations that the disclosure made herein is presented. [Means for solving the problem]

[0009] The present disclosure describes implementations for assemblies for hydraulic gear pumps with force balance and internal cooling features.

[0010] In a first example implementation, the present disclosure describes a gear pump including a pump housing having (i) a pump housing channel, and (ii) an arcuate groove disposed within an inner surface of the pump housing, a pump internal gear disposed within the pump housing and rotatable relative to the pump housing, a pump pinion disposed within the pump internal gear such that external teeth of the pump pinion engage with internal teeth of the pump internal gear, and a pump port block having a first port and a second port, wherein when the pump pinion rotates within the pump internal gear, fluid is drawn from the first port and provided to the second port for discharge, a portion of the fluid provided to the second port is provided to the pump housing channel to cool the pump housing, and the fluid obtained from the pump housing channel is provided to the arcuate groove, and the fluid in the arcuate groove exerts a radially inward force on the pump internal gear.

[0011] In a second example implementation, the disclosure describes an assembly including a main housing having an interior chamber therein, an electric motor disposed within the interior chamber of the main housing, the electric motor including (i) a stator fixedly positioned within the interior chamber of the main housing, and (ii) a rotor positioned within the stator and rotatable relative to the stator, and a gear pump of the first example implementation, the gear pump positioned within the main housing at least partially within the rotor of the electric motor, and a pump pinion mounted to a pump drive shaft and rotatably coupled to the rotor of the electric motor.

[0012] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the exemplary aspects, implementations, and features described above, other aspects, implementations, and features will become apparent by reference to the figures and the following detailed description.

[0013] The novel features believed to be characteristic of the illustrative examples are set forth in the appended claims. However, the illustrative examples as well as their preferred modes of use, other objects, and description thereof will best be understood by reference to the following detailed description of illustrative examples of the present disclosure when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0014] [Figure 1] 1 illustrates a perspective view of an assembly in accordance with an example implementation. [Diagram 2] 2 illustrates a cross-sectional side view of the assembly of FIG. 1 in accordance with an example implementation. [Diagram 3] 2 illustrates a perspective exploded view of the assembly of FIG. 1 according to another example implementation. [Figure 4] 1 illustrates a perspective view of a gear pump in accordance with an example implementation. [Diagram 5] 5 illustrates a cross-sectional side view of the gear pump of FIG. 4 according to an example implementation. [Figure 6] 5 illustrates a perspective exploded view of the gear pump of FIG. 4 according to an example implementation. [Figure 7] 5 illustrates a cross-sectional top view of the gear pump of FIG. 4 showing fluid paths within the assembly during operation, according to an example implementation. [Figure 8A] 1 illustrates a perspective view of a pump housing in accordance with an example implementation. [Figure 8B] 8B illustrates another perspective view of the pump housing of FIG. 8A taken from a different angle, according to an example implementation. [Figure 9A] 1 illustrates a perspective view of a pump housing in accordance with an example implementation. [Figure 9B] 9B illustrates another perspective view of the pump housing of FIG. 9A taken from a different angle, according to an example implementation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present disclosure relates to gear pumps with force balance and internal cooling features. The present disclosure also relates to gear pumps and integrating or embedding electronic drives (e.g., inverters as well as motor controllers) with electric motors with assemblies that provide a compact configuration that reduces cost, saves space, and increases reliability by sharing components.

[0016] According to an example implementation, Fig. 1 illustrates a perspective view of assembly 100, Fig. 2 illustrates a cross-sectional side view of assembly 100, and Fig. 3 illustrates a perspective exploded view of assembly 100. Figs. 1 to 3 will be described collectively.

[0017] The assembly 100 comprises an electric motor 102, a gear pump 104, and an electronic drive 106 integrated together. The assembly 100 includes a main housing 108 having an interior chamber 110 within which the components of the electric motor 102 and the gear pump 104 are disposed.

[0018] The electric motor 102 includes a stator 112 fixedly positioned within an interior chamber 110 of the main housing 108. The stator 112 is configured to generate a magnetic field. In particular, the stator 112 may include windings (not shown) wound around a body (e.g., a lamination stack) of the stator 112 such that, upon providing an electric current through the windings, a magnetic field is generated.

[0019] The electric motor 102 further includes a rotor 114 positioned within the stator 112. The electric motor 102 may further include magnets 116 mounted on the rotor 114 within the annular space between the stator 112 and the rotor 114. In an example, the magnets 116 include two circumferential magnet arrays axially spaced apart about the periphery of the rotor 114, as shown in FIG.

[0020] The magnets 116 are configured to interact with a magnetic field generated by the stator 112 to rotate the rotor 114 and create torque. In other example implementations, different types of electric motors may be used that do not include permanent magnets.

[0021] The gear pump 104 is mounted within a main housing 108, at least partially within a rotor 114 and a stator 112 of an electric motor 102. The assembly 100 has a pump port block 117 having a first port 118, a second port 119, and an exhaust port 120.

[0022] The gear pump 104 is configured as an internal gear pump having a pump pinion 122 (e.g., a spur gear having external teeth formed in a peripheral outer surface) and a pump internal gear 124 (e.g., an internal gear having internal teeth formed in a peripheral inner surface) disposed within a pump housing 202. As depicted in FIG. 2 , the pump pinion 122 is mounted to or is an integral part of a pump drive shaft 126, and the teeth of the pump pinion 122 engage with the teeth of the pump internal gear 124. Further, the pump pinion 122 is eccentrically mounted with respect to the pump internal gear 124, i.e., the center of rotation of the pump pinion 122 is eccentric with respect to or offset from the center of rotation of the pump internal gear 124.

[0023] The pump port block 117 couples to the main housing 108 via a number of fasteners or bolts, such as bolt 127 .

[0024] The rotor 114 has a cylindrical portion 128 and a spindle portion 130. The spindle portion 130 is supported within an electronics housing 132 of the electronic drive 106 via bearings 134 disposed about an outer surface of the spindle portion 130 of the rotor 114 such that the rotor 114 rotates relative to the main housing 108 and the electronics housing 132.

[0025] Pump drive shaft 126 is rotatably coupled to rotor 114 via splined engagement. In particular, pump drive shaft 126 has splines (e.g., splines 204, described below with respect to Figures 4-6) formed about an outer surface of pump drive shaft 126 and configured to engage corresponding splines formed on an inner surface of spindle portion 130 of rotor 114. In this manner, rotor 114 is drivingly connected to pump drive shaft 126 and configured to transfer rotational motion to pump drive shaft 126 during operation.

[0026] As mentioned above, the rotor 114, and specifically the spindle portion 130 of the rotor 114, is supported around the outer surface of the rotor 114 via bearings 134. In addition, the pump drive shaft 126 also supports the rotor 114 at an increased diameter portion 136, which provides support for the inner surface of the rotor 114, as shown in FIG. 2. Thus, the rotor 114 is supported at two locations or points, namely, around the outer surface of the rotor 114, where the bearings 134 support it, and around the inner surface of the rotor 114, where the pump drive shaft 126 supports it. With this configuration, the pump drive shaft 126 provides expanded support for the rotor 114 and may prevent misalignment or twisting of the rotor 114 during operation.

[0027] During operation, as the rotor 114 rotates, the rotational motion of the rotor 114 is transferred to the pump drive shaft 126 through a splined engagement with the pump drive shaft 126. It may be desirable to keep the splined engagement lubricated. Such lubrication extends the life of the components of the assembly 100 (e.g., the rotor 114 and the pump drive shaft 126). For example, grease may be used to lubricate the splined engagement.

[0028] It may be desirable to maintain grease or any lubricating fluid at the site of the spline engagement. Accordingly, assembly 100 includes a first seal 138 (e.g., an O-ring) disposed within a groove 139 (see FIGS. 5 and 7) formed around the outer surface of pump drive shaft 126. Additionally, assembly 100 includes a cap 140 inserted within spindle portion 130 of rotor 114, cap 140 having a second seal 142 (e.g., an O-ring) disposed within a groove formed around a corresponding outer surface of cap 140.

[0029] The first seal 138 and the second seal 142 span the splines of the pump drive shaft 126 and the spindle portion 130. In this manner, any lubricant at the site of spline engagement is sealed off and remains between the first seal 138 and the second seal 142. With this configuration, the lubricant does not have to leak outside the site of spline engagement. As shown in FIG. 2, the assembly 100 further includes a shaft seal 144 that is also disposed about the outer surface of the pump drive shaft 126 and is configured to prevent fluid from leaking from the gear pump 104 into the electric motor 102.

[0030] The electronic drive housing 132 couples to the main housing via bolts, such as bolt 146 shown in FIG. 3. The electronic drive housing 132 couples to the electronics housing cover 148 via a number of fasteners, such as bolt 149 shown in FIG. 1. With this configuration, the electronics housing 132 and the electronics housing cover 148 form an enclosed box in which the electronic boards and components of the electronic drive 106 are disposed. In this manner, the electronic drive 106 is integrated with the electric motor 102 and the gear pump 104 in the assembly 100.

[0031] As shown in FIG. 2, the electronic drive 106 may include one or more electronic boards, such as a controller board 150 and an inverter board 152, electrically coupled to each other and axially offset as depicted. The controller board 150 and the inverter board 152 may be configured as printed circuit boards (PCBs). A PCB mechanically supports and electrically connects electronic components (e.g., microprocessors, integrated chips, capacitors, resistors, etc.) using conductive tracks, pads, and other features etched from one or more copper laminate sheet layers onto and / or between sheet layers of a non-conductive substrate. The components are typically soldered onto the PCB to mechanically fasten as well as electrically connect the components to the PCB.

[0032] The inverter board 152 can be isolated from and coupled to the controller board 150, for example, via standoffs. The inverter board 152 can include a number of conductive bus bars and is configured to receive direct current (DC) power and provide power to components mounted on the inverter board 152.

[0033] As an example, DC power can be provided from a battery to the inverter board 152. With this configuration, the DC power is provided to a bus bar, which then transmits the power to the other components of the inverter board 152.

[0034] The inverter board 152 may be configured as a power converter that converts DC power received at the inverter board 152 into three-phase alternating current (AC) power that can be provided to the windings of the stator 112 to drive the electric motor 102. For example, the inverter board 152 may include a semiconductor switching matrix mounted on the inverter board 152 and configured to be electrically connected to the positive DC terminal and the negative DC terminal. The inverter board 152 may further include a number of capacitors disposed in the axial space between the inverter board 152 and the controller board 150.

[0035] The semiconductor switching matrix may include any arrangement of semiconductor switching elements that aid in the conversion of DC to three-phase power. For example, the semiconductor switching matrix may include three phases, with bridge elements electrically coupled to the input DC terminals and connected to the three-phase AC output terminals.

[0036] In an example, the semiconductor switching matrix includes a plurality of transistors (e.g., insulated gate bipolar transistors or metal oxide semiconductor field effect transistors). The transistors are switchable between an activated or "on" state and a deactivated or "off" state, e.g., via a pulse width modulated (PWM) signal provided by a microprocessor mounted on the controller board 150. The microprocessor may comprise one or more processors. The processor may include a general-purpose processor (e.g., an Intel® single core microprocessor or an Intel® multi-core processor) or a special-purpose processor (e.g., a digital signal processor, a graphics processor, or an application specific integrated circuit (ASIC) processor). The processor may be configured to execute computer-readable program instructions (CRPI) that perform the operations described throughout this specification. The processor may be configured to execute hard-coded functions in addition to or in place of software-coded functions (e.g., via the CRPI).

[0037] When the transistors of the semiconductor switching matrix are activated and deactivated at specific times via the PWM signals, an AC voltage waveform is generated at the AC output terminals. Thus, the voltage waveform at the AC output terminals is pulse width modulated and oscillates between a DC+ potential and a DC- potential. The AC voltage waveform is then provided to the windings of the stator 112 to drive the electric motor 102. The controller board 150 and the inverter board 152 may include several connections to facilitate the transmission and reception of signals and power between each other and to other components of the assembly 100 or to external components.

[0038] The electronic drive 106 may include multiple sensors. For example, the electronic drive 106 may include a temperature sensor configured to provide information indicative of the operating temperature of the electric motor 102 and / or the fluid temperature of the hydraulic fluid flowing through the gear pump 104. The electronic drive 106 may also include a Hall effect current sensor that provides information indicative of the current level in the windings of the stator 112.

[0039] The electronic drive 106 may further include a pressure sensor that indicates the pressure level of the fluid within the assembly 100. The electronic drive 106 may also include a rotational position sensor configured to provide sensor information indicative of the angular position of the rotor 114 and the pump drive shaft 126. The rotational position sensor information can be used by a microprocessor controlling the electric motor 102 to control the speed and torque produced by the rotor 114 in a closed-loop feedback control arrangement.

[0040] For example, the controller board 150 may include a sensor chip or encoder 154 to be mounted near the spindle portion 130 of the rotor 114, as shown in Figure 2. The encoder 154 may be configured to interact with a magnet 156 disposed within the cap 140. The encoder 154 is configured as an electromechanical device that converts the angular position or movement of the rotor 114 into an analog or digital output signal that is provided to a microcontroller that controls the electric motor 102.

[0041] 1-3, the electronic drive 106 may further include an electrical connector 158 configured as a hollow plastic component housing a plurality of conductor pins electrically connected to conductive tracks on the controller board 150. A connector socket (not shown) having female pins may be mounted to or inserted into the electrical connector 158 such that the conductor pins make contact with the female pins of the connector socket. Wires may be connected to the female pins to provide signals to and receive signals from the conductor pins of the electrical connector 158.

[0042] With this configuration, the electronic drive 106 can receive various input and sensor signals via the electrical connector 158 and can provide commands in response to the received information. For example, the electronic drive 106 can receive command signals from a central controller or from a machine input (e.g., a joystick on a hydraulic machine such as a wheel loader, backhoe, or excavator) indicating a desired fluid pressure and fluid flow rate that the gear pump 104 should provide. The electronic drive 106 can then control the AC power provided to the stator 112 to generate a particular speed and torque on the pump drive shaft 126 to achieve the desired fluid pressure level and flow rate. The electronic drive 106 can also provide sensor signals (e.g., obtained from the encoder 154) to another central controller via the electrical connector 158.

[0043] Thus, the electronic drive 106 can be used not only as a controller for the assembly 100, but also as an actuator that is controlled by the assembly 100. In particular, the electronic drive 106 receives command and sensor signals from sensors within the assembly 100 and associated with the actuators, and in response, controls the electric motor 102 and gear pump 104 to achieve the commanded desired movement of the actuators.

[0044] Although the gear pump 104 is described above as being integrated into the assembly 100 that includes the electric motor 102 and the electronic drive 106, the gear pump 104 can be used as a stand-alone pump. Details of the gear pump 104 will now be described.

[0045] According to an example implementation, Fig. 4 illustrates a perspective view of the gear pump 104, Fig. 5 illustrates a cross-sectional side view of the gear pump 104, and Fig. 6 illustrates a perspective exploded view of the gear pump 104. Figs. 4 to 6 will be described collectively.

[0046] Gear pump 104 is mounted and positioned between pump port block 117 and end cover 200. As described above, pump port block 117 includes first port 118, second port 119, and exhaust port 120. Shaft seal 144 is disposed within a cavity formed in end cover 200 and, as a result, is disposed between an inner surface of end cover 200 and an outer surface of pump drive shaft 126.

[0047] The gear pump 104 has a pump housing 202 configured to house the components of the gear pump 104. The pump drive shaft 126 is rotatably coupled to the spindle portion 130 of the rotor 114 via a spindle 204 to provide rotational motion to the pump pinion 122 and pump internal gear 124 via the pump drive shaft 126.

[0048] The pump internal gear 124 and the pump pinion 122 are axially supported within the pump housing 202 via (i) a first thrust plate 206 disposed distally of the pump internal gear 124 and the pump pinion 122, and (ii) a second thrust plate 208 proximal of the pump internal gear 124 and the pump pinion 122. Thus, the pump pinion 122 and the pump internal gear 124 are disposed or sandwiched between the thrust plates 206 and 208. As described below, the thrust plates 206, 208 can act as axial compensators that can reduce leakage within the gear pump 104 and improve the efficiency of the gear pump 104.

[0049] The thrust plates 206, 208 are in turn supported by a first pump cover 210 and a second pump cover 212. In particular, the thrust plate 206 interfaces with the pump cover 210 at an interface 209, and the thrust plate 208 interfaces with the pump cover 212 at an interface 211. The term "interface" is used herein to refer to a point, plane, or space (or a portion of a plane or space) where two components abut and interact (e.g., the thrust plates 206, 208 abut and interact with the pump covers 210, 212, respectively).

[0050] 5 and 6, a first pump cover 210 interfaces with the pump port block 117. Similarly, a second pump cover 212 interfaces with the end cover 200. The pump covers 210, 212 have corresponding recesses or shoulders that axially support the pump housing 202 such that the pump housing 202 is positioned between the pump covers 210 and 212. The gear pump 104 may include a number of face seals at interfaces between different components that prevent fluid from leaking to an environment external to the gear pump 104.

[0051] The pump port block 117, the first pump cover 210, the second pump cover 212, and the end cover 200 have fastener through holes arranged in a circular array such that the pump port block 117, the first pump cover 210, the second pump cover 212, and the end cover 200 can be axially coupled together in a tight axial assembly using bolts 213 (e.g., socket head bolts) as shown in Figure 6. Thus, the pump port block 117, the first pump cover 210, the second pump cover 212, and the end cover 200, as well as the components of the gear pump 104 disposed therebetween, can be aligned and stacked and then fastened together using the bolts 213.

[0052] With this configuration, the gear pump 104 components are positioned between and supported by the pump covers 210, 212, which in turn are supported by the pump port block 117 and the end cover 200. As depicted in FIG. 5, the end cover 200, pump covers 210, 212, and thrust plates 206, 208 include corresponding central through holes that accommodate the pump drive shaft 126 therethrough. The pump port block 117 has a cavity 214 in which the distal end of the pump drive shaft 126 is disposed. Additionally, the gear pump 104 includes bushings 216 and 218 disposed about the pump drive shaft 126 between the outer surface of the gear pump 104 and the inner surfaces of the pump covers 210, 212 and thrust plates 206, 208 to allow the pump drive shaft 126 to rotate. In an example, the bushings 216, 218 may be dry unlubricated (DU) bushings made from steel reinforced bronze or Teflon. The bushings 216, 218 are configured as bearings to facilitate rotation of the pump drive shaft 126.

[0053] The thrust plates 206, 208 are not fastened with bolts 213, but rather are configured as floating components that can move axially as described below to compensate for any axial clearance and reduce internal leakage within the gear pump 104.

[0054] The gear pump 104 is configured to operate as a bi-directional pump. In particular, the first port 118 can operate as an inlet port configured to receive fluid from a fluid reservoir fluidly coupled to the assembly 100 (e.g., via any hydraulic line hose), and the second port 119 can operate as an outlet or discharge port to provide pressurized fluid from the gear pump 104 to be discharged to a hydraulic actuator fluidly coupled to the assembly 100. The hydraulic actuator can be, for example, a hydraulic cylinder having a piston moving linearly therein, or can be a hydraulic motor. In this mode of operation, the pump pinion 122 and pump internal gear 124 rotate in a first rotational direction, and the hydraulic actuator can move in the first direction.

[0055] In another mode of operation, the first port 118 can operate as a discharge port for providing pressurized fluid discharged from the gear pump 104 to the hydraulic actuator, and the second port 119 can operate as an inlet port configured to receive fluid from a fluid reservoir. In this mode of operation, the pump pinion 122 and the pump internal gear 124 rotate in a second rotational direction opposite the first rotational direction, and the hydraulic actuator can move in the second direction opposite the first direction.

[0056] The operation of the gear pump 104 will now be described assuming that the gear pump 104 rotates in a given direction, however, it should be understood that the gear pump 104 can equally well operate in the opposite direction where the operation of the ports and fluid volumes are reversed.

[0057] During operation, as the pump drive shaft 126 rotates, the pump pinion 122 rotates within the pump internal gear 124. As the external gear teeth of the pump pinion 122 and the internal gear teeth of the pump internal gear 124 separate or disengage, an expansion volume (i.e., expansion chamber) is created. The expansion volume collectively represents a number of pockets formed between the separating teeth. The expansion volume acts as a suction void formed between the separating teeth on the intake side of the gear pump 104 that is fluidly coupled to the inlet port (e.g., first port 118). As a result, fluid available from the inlet port fills the expansion volume between the teeth.

[0058] The fluid is conveyed by the gear teeth of the pump pinion 122 and the pump internal gear 124 to another chamber or volume on the discharge side of the gear pump 104 that is fluidly coupled to an outlet port (e.g., second port 119). The meshing of the gear teeth of the pump pinion 122 and the pump internal gear 124 displaces the fluid, which is then provided to the outlet port. Thus, when the gear teeth of the pump pinion 122 and the pump internal gear 124 come into mesh on the discharge side of the gear pump 104, the volume decreases and the fluid is forced out under pressure.

[0059] When the teeth of the pump pinion 122 and the pump internal gear 124 mesh, they form a seal between the expanding volume with the low pressure fluid received from the inlet port and the volume between the meshing or meshing teeth at the discharge or outlet port. The seal created by the meshing teeth forces the fluid out the discharge port and prevents the fluid from flowing back towards the inlet port.

[0060] 5 and 6, the gear pump 104 includes a crescent seal assembly comprising an inner crescent 220 and an upper or outer crescent 222. The terms "inner" and "outer" refer to the radial location of the crescents, with the inner crescent 220 being disposed radially inward relative to the outer crescent 222.

[0061] The inner crescent 220 and the outer crescent 222 are axially supported within the interior space between the pump internal gear 124 and the pump pinion 122 by a first locating pin 224 and a second locating pin 226 depicted in FIG. 2 (locating pin 226 is also shown in FIG. 3). Referring together to FIGS. 5 and 6, the locating pin 224 is partially disposed within a blind hole or cavity formed in the first pump cover 210 and extends through a locating pin through hole 225 in the thrust plate 206 to axially connect with the distal ends of the crescents 220, 222. Similarly, the locating pin 226 is partially disposed within a blind hole or cavity formed in the second pump cover 212 and extends through a locating pin through hole 227 in the thrust plate 208 to axially connect with the proximal ends of the crescents 220, 222.

[0062] With this configuration, the inner crescent 220 and the outer crescent 222 are held in place axially by the locating pins 224, 226, which also maintain the orientation of the crescents 220, 222. In other words, the locating pins 224, 226 axially support the crescent seal assembly (the inner crescent 220 and the outer crescent 222).

[0063] As the pump pinion 122 and pump internal gear 124 rotate during operation of the gear pump 104, the crescents 220, 222 divide the fluid as it is conveyed from the low pressure suction expansion volume to the volume coupled to the discharge port such that the crescents 220, 222 can form a seal between the low pressure volume and the high pressure volume.

[0064] In particular, the outer surface (i.e., the radially outer surface) of the outer crescent 222 interfaces with the internal teeth of the pump internal gear 124 to create a seal therebetween. An effective seal between the outer surface of the outer crescent 222 and the internal teeth of the pump internal gear 124 may prevent leakage from the high pressure volume to the low pressure volume. The terms "impede" or "block" the flow of fluid are used herein to indicate substantially preventing the flow of fluid except for a minimal flow of, for example, drops per minute.

[0065] In a similar manner, the inner surface (i.e., the radially inner surface) of the inner crescent 220 interfaces with the external teeth of the pump pinion 122 to create a seal therebetween. An effective seal between the inner surface of the inner crescent 220 and the external teeth of the pump pinion 122 may prevent leakage from the high pressure volume to the low pressure volume.

[0066] The configuration of the crescent seal assembly of the crescents 220, 222 provides an effective seal and fills any radial gap between the crescents 220, 222 and the gear teeth to create an effective seal. In particular, fluid resulting from an expansion volume or high pressure volume leaking through the interface between the outer crescent 222 and the inner crescent 220 can push the crescents 220, 222 radially apart. As a result, the fluid between the crescents 220, 222 can push the outer crescent 222 radially outward toward the internal teeth of the pump internal gear 124, thereby eliminating any radial space or gap therebetween and creating an effective seal. Similarly, the fluid between the crescents 220, 222 can push the inner crescent 220 radially inward toward the external teeth of the pump pinion 122, thereby eliminating any radial space or gap therebetween and creating an effective seal.

[0067] Additionally, the crescents 220, 222 can be configured such that at least one spring cavity is formed therebetween. The spring cavity can be formed as a recess in an inner surface of the outer crescent 222. In other example implementations, the spring cavity can be formed as a recess in an outer surface of the inner crescent 220. In other examples, both the inner crescent 220 and the outer crescent 222 can have mating or opposing surfaces that form a spring cavity therebetween.

[0068] The spring cavity can receive a spring therein, such as a leaf spring. In addition to the fluid pushing the crescents 220, 222 radially apart, a leaf spring disposed within the spring cavity can also push the crescents 220, 222 radially apart. With this configuration, the leaf spring can push the outer crescent 222 radially outward toward the internal teeth of the pump internal gear 124, thereby increasing the effectiveness of the seal between the outer crescent 222 and the internal teeth of the pump internal gear 124. Similarly, the leaf spring can push the inner crescent 220 radially inward toward the external teeth of the pump pinion 122, thereby increasing the effectiveness of the seal between the inner crescent 220 and the pump pinion 122. A leaf spring is used herein as an example of a biasing element. Other types of springs, such as wave springs or coil springs, can be used.

[0069] Additionally, the crescent seal assembly may include a check valve between the crescents 220 and 222 that prevents fluid flow from the high pressure volume to the low pressure volume regardless of the direction of rotation of the pump drive shaft 126. In particular, the outer crescent 222 and the inner crescent 220 may have recesses or grooves that form a check valve cavity or recess therebetween. A check pin may be positioned within such a check valve cavity.

[0070] Pressurized fluid leaking from the high pressure volume to the low pressure volume between the crescents 220, 222 will force the stop pin against the surface of the crescents 220, 222 which forms a mounting location for the stop pin. As a result, the stop pin creates a seal with the surface of the crescent to prevent leakage past the seal. Another stop pin and check valve cavity located in the opposite direction can prevent or block leakage in the opposite direction when the pump drive shaft 126 rotates in the opposite rotational direction.

[0071] As a result, this configuration of the crescent seal assembly allows the gear pump 104 to be bidirectional. Whether fluid is being drawn in through the first port 118 and then displaced to the second port 119, or vice versa, the stop pin acts as a reverse check valve blocking leakage fluid flow in either direction. Additional stop pins can be added to further strengthen the seal between the intake and discharge sides of the gear pump 104.

[0072] 6, distal to the pump pinion 122 and pump internal gear 124, the first pump cover 210 can have through holes 228 and 230 corresponding to and aligned with the first and second ports 118 and 119, respectively, to allow fluid communication through the first pump cover 210. Similarly, the thrust plate 206 has generally kidney-shaped through holes 232 and 234 to allow fluid communication therethrough.

[0073] Proximal to the pump pinion 122 and the pump internal gear 124, the thrust plate 208 has a number of through holes, such as through holes 236, 238, among others, that allow fluid communication therethrough. As a result, the fluid in the expansion volume and in the expansion and high pressure volumes formed between the pump pinion 122 and the pump internal gear 124 can communicate in both axial directions via the through holes in the thrust plates 206, 208. As a result, the fluid reaches the interfaces 209, 211 between the thrust plates 206, 208 and the pump covers 210, 212, respectively (see FIG. 5).

[0074] Fluid trapped at an interface 209 between the thrust plate 206 and the first pump cover 210 exerts an axial fluid force on the thrust plate 206 towards the distal end faces of the pump pinion 122 and the pump internal gear 124. In this manner, a metal-to-metal seal is created between the thrust plate 206 and the distal end faces of the pump pinion 122 and the pump internal gear 124. Similarly, fluid trapped at an interface 211 between the thrust plate 208 and the second pump cover 212 exerts an axial fluid force on the thrust plate 208 towards the proximal end faces of the pump pinion 122 and the pump internal gear 124. In this manner, a metal-to-metal seal is created between the thrust plate 208 and the proximal end faces of the pump pinion 122 and the pump internal gear 124.

[0075] Fluid forces acting on the thrust plates 206, 208 towards the pump pinion 122 and pump internal gear 124 push or compress the thrust plates 206, 208 axially against the pump pinion 122 and pump internal gear 124, thereby creating an effective seal and eliminating any axial gap therebetween. Thus, the thrust plates 206, 208 can be referred to as axial compensators because they can compensate for any axial gap between the thrust plates 206, 208 and the pump pinion 122 and pump internal gear 124 disposed therebetween, thereby reducing leakage and improving the efficiency of the gear pump 104.

[0076] 6, the gear pump 104 may include a first set of seals, such as a first set of kidney-shaped seals 240, that may be disposed in a contoured seal cavity or recess on the distal side of the thrust plate 206, the recess having a shape that matches the shape of the first set of kidney-shaped seals 240. With this configuration, the first set of kidney-shaped seals 240 isolate or seal the high pressure fluid (derived from the high pressure volume) communicating with the interface 209 between the thrust plate 206 and the first pump cover 210 from the low pressure fluid (derived from the expansion volume) communicating with the interface 209 between the thrust plate 206 and the first pump cover 210. As a result, the first set of kidney-shaped seals 240 may prevent cross-flow or leakage from the high pressure side to the low pressure side.

[0077] Similarly, the gear pump 104 may include a second set of seals, such as a second set of kidney-shaped seals 242 disposed in contoured seal cavities or recesses proximal to the thrust plate 208, the recesses having a shape matching the shape of the second set of kidney-shaped seals 242. The second set of kidney-shaped seals 242 may isolate or seal high pressure fluid (derived from the high pressure volume) communicating with the interface 211 between the thrust plate 208 and the second pump cover 212 from low pressure fluid (derived from the expansion volume) communicating with the interface 211 between the thrust plate 208 and the second pump cover 212. As a result, the second set of kidney-shaped seals 242 may prevent cross-flow or leakage from the high pressure side to the low pressure side.

[0078] 5, the second pump cover 212 may have a channel (not shown) configured to fluidly communicate with a cavity or recess 244 in the end cover 200 at the interface 211 between the second pump cover 212 and the thrust plate 208. The recess 244 is then fluidly coupled to the exhaust port 120 through an exhaust passage 246 which exhausts any high pressure fluid that reaches the end cover 200 to reduce the internal pressure within the gear pump 104.

[0079] Similarly, the first pump cover 210 may have a channel (not shown) that may be in fluid communication with a cavity 214 in the pump port block 117. The cavity 214 is then fluidly coupled to the exhaust port 120 through an exhaust passage 248 that exhausts any high pressure fluid that reaches the pump port block 117, reducing the internal pressure within the gear pump 104.

[0080] As mentioned above, an expanded volume is created at low pressure when the external teeth of the pump pinion 122 separate from the internal teeth of the pump internal gear 124 on the intake side of the gear pump 104. On the discharge side of the gear pump 104, when the external teeth of the pump pinion 122 mesh with the internal teeth of the pump internal gear 124, the reduced volume forces fluid out under pressure.

[0081] Such pressurized fluid between the pump pinion 122 and the pump internal gear 124 at the discharge side can exert a radially outward force on the pump internal gear 124 towards the pump housing 202. As a result, friction and wear can occur at the interface between the pump internal gear 124 and the pump housing 202 in the area where the radially outward force pushes the pump internal gear 124 towards the pump housing 202.

[0082] Such interface areas may differ based on the direction of rotation of the pump pinion 122. In particular, areas prone to wear or subject to friction when the pump pinion 122 is rotating in a first direction (e.g., when the first port 118 is an inlet port and the second port 119 is an outlet port) may differ from corresponding areas prone to wear or subject to friction when the pump pinion 122 is rotating in a second direction (e.g., when the second port 119 is an inlet port and the first port 118 is an outlet port).

[0083] Additionally, heat is generated during operation that may cause damage to the components of the gear pump 104. The gear pump 104 disclosed herein is configured to counteract and reduce frictional forces resulting from the high pressure fluid exerting a radially outward force on the pump internal gear 124, and is also configured to provide a cooling circuit to cool at least some of the gear pump 104 components.

[0084] 7 illustrates a cross-sectional top view of a gear pump 104, showing the fluid paths within the assembly during operation, according to an example implementation. The cross-sectional top view of FIG. 7 is taken along a plane perpendicular to the corresponding plane of the cross-sectional side view of FIG.

[0085] 7, the first port 118 is an inlet port that receives fluid from a fluid reservoir, and the second port 119 is an outlet port where the gear pump 104 releases pressurized fluid to the hydraulic actuator. Fluid received at the first port 118 flows through an inlet fluid passage 700 and into an expansion chamber created when the pump pinion 122 rotates inside the pump internal gear 124. As the pump pinion 122 rotates inside the pump internal gear 124, the fluid is forced under pressure into an outlet fluid passage 702, which then provides the fluid to the second port 119.

[0086] Additionally, the fluid provided to the second port 119 is used to cool the pump housing 202. In particular, a portion of the fluid obtained from the outlet fluid passage branches or redirects to flow through a channel 704 formed in the pump port block 117, then through a channel 706 formed in the pump cover 210 that is aligned with the channel 704, and then through a first pump housing channel 708 formed in the pump housing 202.

[0087] According to an example embodiment, Figure 8A illustrates a perspective view of the pump housing 202 and Figure 8B illustrates another perspective view of the pump housing 202 taken from a different angle. With joint reference to Figures 7 and 8A, a first pump housing channel 708 in the pump housing 202 is angled and provides fluid through an opening or hole 800 in the pump housing to a first arcuate groove 802 formed in an inner surface of the pump housing 202.

[0088] As the pump internal gear 124 rotates, fluid received through the holes 800 can circulate within a gap or annular space between the outer surface of the pump internal gear 124 and the inner surface of the pump housing 202 and is provided to the second arcuate groove 804 shown in FIG. 8B. The pump housing 202 includes a hole 806 disposed within the second arcuate groove 804. As shown, the second arcuate groove 804 is angularly spaced from the first arcuate groove 802 along the peripheral inner surface of the pump housing 202.

[0089] 7 and 8B together, fluid in second arcuate groove 804 is provided through hole 806 to second pump housing channel 710, then through channel 712 formed in pump cover 210, and then through channel 714 formed in pump port block 117, which channel 714 aligns with channel 712. The fluid then combines with fluid available from first port 118 and is provided to an expansion chamber formed between the teeth of pump pinion 122 and pump internal gear 124.

[0090] Thus, fluid obtained from the outlet fluid passage 702 may circulate through the pump housing 202, thereby cooling the pump housing 202 and reducing the temperature of the pump housing 202. Additionally, the fluid provided to the first arcuate groove 802 may reduce wear and friction between the pump internal gear 124 and the pump housing 202.

[0091] As mentioned above, pressurized fluid between the pump pinion 122 and the pump internal gear 124 exerts a radially outward force on the pump internal gear 124 towards the pump housing 202. Pressurized fluid provided through the outlet fluid passage 702 and the first pump housing channel 708 can accumulate in the first arcuate groove 802, which acts as a pocket of fluid. The pressurized fluid in the first arcuate groove 802 exerts a radially inward force on the pump internal gear 124 that opposes or balances the radially outward force acting on the pump internal gear 124. As a result, friction between the pump internal gear 124 and the pump housing 202 is reduced and wear on the pump internal gear 124 and the pump housing 202 may be reduced.

[0092] Notably, as noted above, when the gear pump 104 is configured to be bidirectional and the pump drive shaft 126 is driven in the opposite direction with the second port 119 being the inlet port, the areas subject to wear may be different. In this case, a corresponding portion of the pressurized fluid is provided to the second arcuate groove 804 rather than the first arcuate groove 802, and the pressurized fluid in the second arcuate groove 804 exerts a corresponding radially inward force that counters the radially outward force of the fluid being compressed by the teeth of the pump pinion 122 and the pump internal gear 124. In other words, the action of the channels and grooves of the gear pump 104 is reversed when the gear pump 104 reverses direction.

[0093] Although the holes 800, 806 are shown disposed within their corresponding arcuate grooves, in other example implementations, they are not disposed within the grooves, in other words, the arcuate grooves can be circumferentially or angularly spaced from the holes.

[0094] According to an example embodiment, Figure 9A illustrates a perspective view of a pump housing 900, and Figure 9B illustrates another perspective view of the pump housing 900 taken from a different angle. The pump housing 900 has a first arcuate groove 902 and a second arcuate groove 904.

[0095] Pump housing 900 differs from pump housing 202 in that bore 800 is not disposed within first arcuate groove 902 and bore 806 is not disposed within second arcuate groove 904. Rather, first arcuate groove 902 is angularly spaced from bore 800 and second arcuate groove 904 is angularly spaced from bore 806.

[0096] Fluid is provided from the first pump housing channel 708 through the holes 800 and is then drawn into the first arcuate groove 902 where fluid accumulates when the gear pump 104 is operating in a first direction as the pump internal gear 124 rotates within the pump housing 900. When the gear pump 104 operates in a second direction, fluid is provided from the second pump housing channel 710 through the holes 806 and is then drawn into the second arcuate groove 904 where fluid accumulates when the pump internal gear 124 rotates within the pump housing 900.

[0097] Thus, the arcuate grooves (e.g., arcuate grooves 902, 904) may be located in areas of the inner surface of the pump housing that experience the most friction. In this manner, wear may be reduced and the life of the pump housing and pump internal gears may be improved.

[0098] The above detailed description, with reference to the accompanying figures, describes various features and operations of the disclosed system. The example implementations described herein are not meant to be limiting. Certain aspects of the disclosed system can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0099] Additionally, unless the context suggests otherwise, the features illustrated in each of the figures may be used in combination with one another. Thus, the figures should generally be viewed as aspects of components of one or more overall implementations, with the understanding that not all illustrated figures are required for each implementation.

[0100] In addition, any recitation of elements, blocks, or steps in this specification or claims is for the sake of clarity, and therefore such recitation should not be construed as requiring or implying that these elements, blocks, or steps be in any particular sequence or performed in a particular order.

[0101] Further, the device or system may be used or configured to perform the functions presented in the figures. In some instances, the device and / or system components may be configured to perform the functions such that they are actually configured and structured (using hardware and / or software) to enable such performance. In other instances, the device and / or system components may be arranged such that they are adapted to perform the functions, capable of performing the functions, or suitable to perform the functions, such as when operating in a particular manner.

[0102] The term "substantially" means that the recited property, parameter, or value need not be achieved exactly, but rather that deviations or variations, including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those of skill in the art, may occur in an amount that does not interfere with the effect that the property is intended to provide.

[0103] The arrangements described herein are for example purposes only. Thus, those skilled in the art will recognize that other arrangements and other elements (e.g., machines, interfaces, operations, sequences, and groups of operations, etc.) can be substituted, and some elements may be eliminated entirely, depending on the desired results. Furthermore, many of the described elements are functional entities that may be implemented as separate or distributed components, or in conjunction with other components, in any suitable combination and location.

[0104] Although various aspects and implementations have been described 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 only and are not intended to be limiting, with the scope being set forth in the following claims, together with the full scope of equivalents to which such claims are entitled. Additionally, the terminology used herein is for the purpose of describing particular implementations only and is not limiting.

[0105] Accordingly, embodiments of the present disclosure may relate to one of the enumerated example embodiments (EEE) described below.

[0106] EEE1 is a gear pump comprising: a pump housing having (i) a pump housing channel, and (ii) an arcuate groove disposed within an inner surface of the pump housing; a pump internal gear disposed within the pump housing and rotatable relative to the pump housing; a pump pinion disposed within the pump internal gear such that its external teeth engage with internal teeth of the pump internal gear; and a pump port block having a first port and a second port, wherein as the pump pinion rotates within the pump internal gear, fluid is drawn from the first port and provided to the second port for discharge, a portion of the fluid provided to the second port is provided to the pump housing channel to cool the pump housing, and the fluid obtained from the pump housing channel is provided to the arcuate groove, and the fluid in the arcuate groove exerts a radially inward force on the pump internal gear.

[0107] EEE2 is the gear pump of EEE1, where the pump housing further comprises a bore fluidly coupled to the pump housing channel such that fluid flows from the pump housing channel through the gear pump to the arcuate groove.

[0108] EEE3 is a gear pump of EEE2, where the bore is located inside the arcuate groove.

[0109] EEE4 is a gear pump of EEE2 or EEE3, where the arcuate grooves are angularly spaced along the inner surface of the pump housing from the bore, and when the pump pinion rotates, the pump internal gear rotates, thereby providing fluid received through the bore to the arcuate grooves.

[0110] EEE5 is any of the gear pumps EEE1 to EEE4, in which, when the pump pinion rotates, fluid provided to the second port between the external teeth of the pump pinion and the internal teeth of the pump internal gear exerts a radially outward force on the pump internal gear, and the radially inward force exerted by the fluid in the arcuate groove counteracts the radially outward force exerted on the pump internal gear.

[0111] EEE6 is any of the gear pumps EEE1 to EEE5, the pump housing channel is a first pump housing channel, and the pump housing further includes a second pump housing channel, and when the pump internal gear rotates, fluid received through the first pump housing channel is provided to the second pump housing channel, and the fluid in the second pump housing channel then merges with the fluid received through the first port.

[0112] EEE7 is the gear pump of EEE6, wherein the arcuate groove is a first arcuate groove, and the pump housing further comprises a second arcuate groove angularly spaced along an inner surface of the pump housing from the first arcuate groove, and when the pump pinion rotates in the opposite direction inside the pump internal gear, fluid is drawn from the second port and provided to the first port for discharge, a corresponding portion of the fluid provided to the first port is diverted into a second pump housing channel to cool the pump housing, and fluid obtained from the second pump housing channel is provided to the second arcuate groove, and the fluid in the second arcuate groove exerts a corresponding radially inward force on the pump internal gear.

[0113] EEE8 is any of the gear pumps EEE1 to EEE7, further comprising a pump cover positioned between the pump port block and the pump housing, the pump cover having a channel aligned with the pump housing channel, and a portion of the fluid diverted into the pump housing channel flows through the channel in the pump cover to the pump housing channel.

[0114] EEE9 is the gear pump of EEE8, further including a thrust plate interposed between the pump cover and the pump internal gear, and a seal disposed within a seal cavity formed at the interface between the thrust plate and the pump cover.

[0115] EEE10 is the gear pump of EEE9, further comprising a crescent seal assembly having an outer crescent and an inner crescent disposed within the pump internal gear between the pump pinion and the pump internal gear, and a locating pin disposed within a cavity formed in the pump cover such that it protrudes axially from the pump cover, the thrust plate including a locating pin through hole, the locating pin extending through the locating pin through hole and protruding from the thrust plate to connect with the crescent seal assembly, thereby axially supporting the crescent seal assembly.

[0116] EEE11 includes a main housing having an internal chamber therein, an electric motor disposed within the internal chamber of the main housing, the electric motor having (i) a stator fixedly positioned within the internal chamber of the main housing, and (ii) a rotor positioned within the stator and rotatable relative to the stator, and a gear pump positioned at least partially within the rotor of the electric motor within the main housing, the pump housing having (i) a pump housing channel, and (ii) an arcuate groove disposed within an inner surface of the pump housing, a pump internal gear disposed within the pump housing and rotatable relative to the pump housing, a pump internal gear disposed within the pump internal gear such that external teeth engage internal teeth of the pump internal gear. a gear pump including a pump port block having a first port and a second port, wherein as the rotor of the electric motor rotates the pump pinion inside the pump internal gear, fluid is drawn from the first port and provided to the second port for discharge, a portion of the fluid provided to the second port is fed into a pump housing channel to cool the pump housing, and fluid obtained from the pump housing channel is provided to an arcuate groove, and the fluid in the arcuate groove exerts a radially inward force on the pump internal gear.

[0117] EEE12 is an assembly of EEE11, where the rotor comprises (i) a cylindrical portion in which the gear pump is at least partially disposed, and (ii) a spindle portion, and the pump drive shaft is rotatably coupled to the spindle portion of the rotor.

[0118] EEE13 is an assembly of EEE12, wherein the pump drive shaft is rotatably coupled to the rotor spindle portion via a splined engagement, the assembly including a first seal and a second seal, the splined engagement being disposed between the first seal and the second seal, such that lubricant is sealed at the splined engagement between the first seal and the second seal.

[0119] EEE14 is an assembly of EEE13, further comprising a cap disposed on the end of the rotor spindle portion, the first seal being disposed in a first groove around an outer surface of the pump drive shaft and the second seal being disposed in a second groove around a corresponding outer surface of the cap.

[0120] EEE15 is an assembly of any of EEE11 to EEE14, and further includes an electronics housing connected to the main housing, an electronics housing cover connected to the electronics housing such that the electronics housing cover and the electronics housing form a sealed box, and one or more electronic boards disposed in the sealed box.

[0121] EEE16 is an assembly of EEE15, where the one or more electronic boards include an inverter board having a semiconductor switching matrix mounted thereon, the semiconductor switching matrix comprising a plurality of semiconductor switching elements configured to convert DC power to three-phase AC power for driving an electric motor, and a controller board axially offset from the inverter board, electrically coupled to the inverter board, and comprising a processor configured to generate switching signals to operate the semiconductor switching matrix.

[0122] EEE17 is an assembly of EEE16, where the controller board further comprises an encoder configured to interact with a magnet mounted on the controller board and coupled to the rotor to provide sensor information indicative of the rotational position of the rotor to the processor.

[0123] EEE18 is any of the assemblies EEE11 to EEE17, in which, when the pump pinion rotates, fluid provided at the second port between the external teeth of the pump pinion and the internal teeth of the pump internal gear applies a radially outward force to the pump internal gear, and the radially inward force applied by the fluid in the arcuate groove counteracts the radially outward force applied to the pump internal gear.

[0124] EEE19 is an assembly of any of EEE11 to EEE18, wherein the pump housing channel is a first pump housing channel, and the pump housing further includes a second pump housing channel, and when the pump internal gear rotates, fluid received through the first pump housing channel is provided to the second pump housing channel, and the fluid in the second pump housing channel then merges with the fluid received through the first port.

[0125] EEE20 is an assembly of EEE19, wherein the arcuate groove is a first arcuate groove, and the pump housing further comprises a second arcuate groove angularly spaced along an inner surface of the pump housing from the first arcuate groove, and when the rotor rotates the pump pinion in an opposite direction inside the pump internal gear, fluid is drawn from the second port and provided to the first port for discharge, a corresponding portion of the fluid provided to the first port is diverted into a second pump housing channel to cool the pump housing, and fluid obtained from the second pump housing channel is provided to the second arcuate groove, and the fluid in the second arcuate groove exerts a corresponding radially inward force on the pump internal gear.

Claims

1. A gear pump comprising: a pump housing having (i) a pump housing channel, (ii) one or more arcuate grooves disposed within an interior surface of the pump housing, and (iii) one or more holes disposed within the interior surface of the pump housing and fluidly coupled to the pump housing channel, wherein at least one of the one or more holes is disposed outside of the one or more arcuate grooves; a pump internal gear disposed within the pump housing and rotatable relative to the pump housing; a pump pinion disposed within the pump internal gear such that the pump pinion's external teeth engage the internal teeth of the pump internal gear; a pump port block having a first port and a second port, wherein when the pump pinion rotates inside the pump internal gear, the fluid is drawn from the first port and provided to the second port for discharge, a portion of the fluid provided to the second port is provided to the pump housing channel to cool the pump housing, and when the pump pinion rotates, the pump internal gear rotates such that at least a portion of the fluid received through the at least one hole located outside the one or more arcuate grooves is provided to at least one of the one or more arcuate grooves, and the fluid in the arcuate groove applies a radially inward force to the pump internal gear.

2. A gear pump as described in claim 1, wherein at least one of the holes is positioned inside an arcuate groove which is one of the one or more arcuate grooves.

3. A gear pump as described in claim 1, wherein when the pump pinion rotates, fluid provided to the second port between the external teeth of the pump pinion and the internal teeth of the pump internal gear exerts a radially outward force on the pump internal gear, and the radially inward force exerted by the fluid within the one or more arcuate grooves opposes the radially outward force applied to the pump internal gear.

4. A gear pump as described in claim 1, wherein the pump housing channel is a first pump housing channel, the pump housing further comprising a second pump housing channel, and when the pump internal gear rotates, the fluid received through the first pump housing channel is provided to the second pump housing channel, and the fluid in the second pump housing channel then merges with the fluid received through the first port.

5. When the pump pinion rotates in the opposite direction inside the pump internal gear, fluid is drawn from the second port and provided to the first port for discharge, a corresponding portion of the fluid provided to the first port is diverted into the second pump housing channel to cool the pump housing, and the fluid obtained from the second pump housing channel is provided to an arcuate groove, one of the one or more arcuate grooves, and the fluid in the arcuate groove exerts a corresponding radially inward force on the pump internal gear. The gear pump according to claim 4.

6. A pump cover interposed between the pump port block and the pump housing, the pump cover having a channel aligned with the pump housing channel, wherein a portion of the fluid diverted into the pump housing channel flows through the channel of the pump cover into the pump housing channel. The gear pump of claim 1 further comprising:

7. A thrust plate disposed between the pump cover and the pump internal gear; a seal disposed within a seal cavity formed at an interface between the thrust plate and the pump cover; The gear pump of claim 6 further comprising:

8. A crescent seal assembly having an outer crescent and an inner crescent disposed within the pump internal gear between the pump pinion and the pump internal gear; a locating pin disposed within a cavity formed in said pump cover such that it projects axially from said pump cover, said thrust plate including a locating pin through hole, said locating pin extending through said locating pin through hole and projecting from said thrust plate to connect with said crescent seal assembly, thereby axially supporting said crescent seal assembly; The gear pump of claim 7 further comprising:

9. An assembly comprising: a main housing having an interior chamber therein; an electric motor disposed within the interior chamber of the main housing, the electric motor including: (i) a stator fixedly positioned within the interior chamber of the main housing; and (ii) a rotor positioned within the stator and rotatable relative to the stator; 9. A gear pump according to any one of claims 1 to 8, positioned within the main housing at least partially within the rotor of the electric motor, a gear pump, the pump pinion being mounted on a pump drive shaft and rotatably coupled to the rotor of the electric motor; An assembly comprising:

10. An assembly as described in claim 9, wherein the rotor has (i) a cylindrical portion in which the gear pump is at least partially disposed, and (ii) a spindle portion, and the pump drive shaft is rotatably connected to the spindle portion of the rotor.

11. An assembly as described in claim 10, wherein the pump drive shaft is rotatably coupled to the spindle portion of the rotor via a splined engagement, the assembly comprising a first seal and a second seal, the splined engagement being located between the first seal and the second seal, such that lubricant is sealed in the splined engagement between the first seal and the second seal.

12. A cap disposed on an end of the spindle portion of the rotor, the first seal being disposed in a first groove around an outer surface of the pump drive shaft and the second seal being disposed in a second groove around a corresponding outer surface of the cap. The assembly of claim 11 further comprising:

13. An electronic device housing connected to the main housing; an electronics housing cover coupled to the electronics housing such that the electronics housing cover and the electronics housing form an enclosed box; one or more electronic boards disposed within said enclosure; The assembly of claim 9 further comprising:

14. The one or more electronic boards an inverter board having a semiconductor switching matrix mounted thereon, the semiconductor switching matrix comprising a plurality of semiconductor switching elements configured to convert DC power to three-phase AC power for driving the electric motor; a controller board axially offset from the inverter board and electrically coupled to the inverter board, the controller board including a processor configured to generate switching signals to operate the semiconductor switching matrix; The assembly of claim 13 comprising:

15. The assembly described in claim 14, wherein the controller board further comprises an encoder configured to interact with a magnet mounted on the controller board and coupled to the rotor to provide sensor information indicative of the rotational position of the rotor to the processor.

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