Electric and hydraulic machines

Abstract

This invention relates to electric and hydraulic machines. An electric and hydraulic machine includes: a housing defining a motor chamber and a pump chamber; a motor including a rotor and a stator positioned within the motor chamber; and a pump including a pumping element positioned within the pump chamber, the pumping element being movable by the motor to discharge fluid from the pump chamber. The pump chamber includes a low-pressure chamber and a high-pressure chamber, a unit inlet defined by the housing and communicating with the low-pressure chamber, and a unit outlet defined by the housing and communicating with the high-pressure chamber. The pump chamber is positioned radially inward of the motor chamber such that the pump is nested within the motor. A radial cooling channel extends radially from the low-pressure chamber to the motor chamber, such that fluid in the pump chamber communicates with the rotor and the stator to cool the motor.

Description

Technical Field

[0001] This disclosure relates to an electric and hydraulic machine. More specifically, this disclosure relates to an integrated motor / pump arrangement. Summary of the Invention

[0002] In one aspect, an electro-hydraulic machine includes: a housing defining a motor chamber and a pump chamber; a motor including a rotor and a stator positioned within the motor chamber; and a pump including a pumping element positioned within the pump chamber. The pumping element is movable by the motor to discharge fluid from the pump chamber. The pump chamber includes a low-pressure chamber and a high-pressure chamber, a unit inlet defined by the housing and communicating with the low-pressure chamber, and a unit outlet defined by the housing and communicating with the high-pressure chamber. The pump chamber is positioned radially inward of the motor chamber such that the pump is nested within the motor. The electro-hydraulic machine further includes a radial cooling channel extending radially from the low-pressure chamber to the motor chamber, such that fluid in the pump chamber communicates with the rotor and the stator to cool the motor.

[0003] In another aspect, a method of operating an electric and hydraulic machine includes: providing working fluid to a low-pressure chamber of a pump via an inlet; actuating a motor within a housing, the motor being located in a motor chamber defined by the housing; driving the pump by means of the motor to discharge the working fluid from the low-pressure chamber; providing the working fluid discharged by the pump to an outlet of the pump; and cooling the motor with the working fluid by guiding a first portion of the working fluid from the low-pressure chamber through a radial cooling channel to the motor chamber.

[0004] In another aspect, an electro-hydraulic machine includes: a housing defining a motor chamber and a pump chamber; a motor including a rotor and a stator positioned within the motor chamber; and a pump including a pumping element positioned within the pump chamber. The pumping element is movable by the motor to discharge fluid from the pump chamber. The pump chamber includes a low-pressure chamber and a high-pressure chamber, a unit inlet defined by the housing and communicating with the low-pressure chamber, and a unit outlet defined by the housing and communicating with the high-pressure chamber. The pump chamber is positioned radially inward of the motor chamber such that the pump is nested within the motor. The electro-hydraulic machine further includes a first flow path for working fluid for the pump, the first flow path extending from the low-pressure chamber to the pumping element, reaching the high-pressure chamber, and reaching the unit outlet. The electro-hydraulic machine further includes a second flow path for working fluid for the pump, the second flow path extending from the low-pressure chamber through a radially outwardly extending radial cooling channel and entering the motor chamber.

[0005] In another aspect, an electro-hydraulic machine includes: a first housing defining a first motor chamber and a first pump chamber; a first motor including a rotor and a stator positioned within the first motor chamber; and a first pump including a first pumping element positioned within the first pump chamber. The first pumping element is movable by the first motor to discharge fluid from the first pump chamber. The first pump chamber includes a low-pressure chamber and a high-pressure chamber, a unit inlet defined by the first housing and communicating with the low-pressure chamber, and a unit outlet defined by the first housing and communicating with the high-pressure chamber. The first pump chamber is positioned radially inward of the first motor chamber such that the first pump is nested within the first motor. The electro-hydraulic machine further includes: a second housing defining a second motor chamber and a second pump chamber, the second housing being axially aligned with and coupled to the first housing; a second motor including a rotor and a stator positioned within the second motor chamber; and a second pump including a second pumping element positioned within the second pump chamber. The second pumping element is movable by the second motor to discharge fluid from the second pump chamber. The second pump chamber includes a low-pressure chamber and a high-pressure chamber, a unit inlet that interconnects the low-pressure chamber of the first pump with the low-pressure chamber of the second pump, and a unit outlet that interconnects the high-pressure chamber of the first pump with the high-pressure chamber of the second pump.

[0006] In another aspect, a method of operating an electric and hydraulic machine includes: providing working fluid to a low-pressure chamber of a first pump via an inlet; providing the working fluid to a low-pressure chamber of a second pump via the low-pressure chamber of the first pump and an inlet of a second pump, without being pressurized by the first pump; driving the first pump with a first motor to discharge the working fluid from the low-pressure chamber of the first pump; driving the second pump with a second motor to discharge the working fluid from the low-pressure chamber of the second pump; providing the working fluid discharged by the first pump to a high-pressure chamber of the first pump and to an outlet of the first pump; and providing the working fluid discharged by the second pump to the high-pressure chamber of the first pump via the outlet of the second pump.

[0007] In another aspect, an electro-hydraulic machine includes a first pump-motor arrangement located within a first housing and including a first pump nested within a first motor, the first pump including a low-pressure chamber and a high-pressure chamber. The electro-hydraulic machine further includes a second pump-motor arrangement located within a second housing and including a second pump nested within a second motor, the second pump including a low-pressure chamber and a high-pressure chamber. The first housing is coupled to the second housing. The low-pressure chambers of the first pump and the second pump together form a single low-pressure chamber. Attached Figure Description

[0008] Figure 1 It is a 3D diagram of electric and hydraulic machines.

[0009] Figure 2 yes Figure 1 A sectional perspective view of an electric and hydraulic machine, showing components of an electric motor.

[0010] Figure 3 It is a cross-sectional view of the electric motor and the first housing component of an electric and hydraulic machine.

[0011] Figure 4 It is a perspective view of the hydraulic mechanism and the second housing component of the electric and hydraulic machine.

[0012] Figure 5 It is a cross-sectional view of an electric and hydraulic machine.

[0013] Figure 6 It is a cross-sectional view of an electric and hydraulic machine, illustrating the various flow paths passing through it.

[0014] Figure 7 It is an axial end section view of an electric and hydraulic machine, illustrating the various flow paths passing through it.

[0015] Figure 8 It is a cross-sectional view of multiple electric and hydraulic machines stacked axially.

[0016] Figure 9 It is a cross-sectional view of the axially stacked structure, illustrating the various flow paths passing through it.

[0017] Figure 10 It is a schematic representation of axial stacking. Detailed Implementation

[0018] Before explaining any embodiments of this disclosure in detail, it should be understood that this disclosure is not limited in its application to the details of the construction and the arrangement of components set forth in the following description or illustrated in the following drawings. This disclosure can have other embodiments and can be practiced or performed in various ways.

[0019] Figure 1 The diagram illustrates an electric and hydraulic machine 10, which defines a motor 30 and a pump 44. A housing 12 includes a first housing member 14 and a second housing member 16, which together surround the motor 30 and the pump 44 and at least partially define the extent of the motor 30 and the pump 44. The pump 44 is nested within the motor 30 such that the motor 30 surrounds the pump 44 in the radial direction (arrow 90). An axial direction is defined perpendicular to the radial direction and indicated by arrow 92. Figure 5 The pump elements (internal gear 56, external gear 58, and gear pump crescent body 60) are shown in more detail in the diagram. Figure 4 The axial range of the pump 44 lies within the axial range of the motor elements (rotor 32, stator 34). In other words, the pump 44 is nested within the motor 30 such that radial lines drawn outward from any pump element also extend through the motor element. The pump and motor elements are described in more detail below.

[0020] Housing 12 includes a unit inlet 18 and a unit outlet 20. As shown, both unit inlet 18 and unit outlet 20 are located at the same axial end of housing 12. In other embodiments, unit inlet 18 and unit outlet 20 may be located at opposite axial ends of housing 12. Unit inlet 18 is an opening in housing 12 that supplies pumped fluid to pump chamber 46, and unit outlet 20 provides an exit outlet from pump chamber 46 for fluid discharged by pump 44. Figure 2 As shown, unit inlet 18 and unit outlet 20 are located radially inside motor 30. Therefore, fluid entering unit inlet 18 moves axially through pump chamber 46. Based on the positions of unit inlet 18 and pump chamber 46, fluid entering the electro-hydraulic machine 10 travels radially outward to reach motor 30 and enter motor chamber 28.

[0021] refer to Figure 1 The first housing member 14 is fastened to the second housing member 16 via a plurality of fasteners 22 positioned around the outer periphery of the electric and hydraulic machine 10. A seal (not shown) may be positioned at the joint between the two housing members 14, 16 to create a fluid-tight seal therebetween. Figure 2As shown, the motor includes a rotor 32 and a stator 34. The rotor 32 is radially positioned within and axially aligned with the stator 34, such that the rotor 32 is nested within the stator 34 and configured to rotate relative to the stator 34 upon actuation. The stator 34 includes windings and further includes a plurality of axial stator bores 36 positioned around the outer periphery of the stator 34. The axial stator bores 36 provide cooling passages for the motor 30, as described in more detail below. As shown, the motor 30 is a permanent magnet motor, and the rotor 32 is cylindrical / annular and includes permanent magnets 40 on the outer radial surface of the windings 38 near the stator 34. The motor 30 may be, for example, an induction motor, a surface permanent magnet motor, an internal permanent magnet motor, a wound rotor, or a switched reluctance motor.

[0022] Figure 3 The motor chamber 28 is shown in more detail relative to the first housing component 14. Figure 3 Pump elements 56, 58, and 60 are not shown in the diagram; they are relative to... Figure 4 The second housing member 16 is shown otherwise. The motor chamber 28 is defined by the housing 12 in both its axial (defined in the first axial range via the first housing member 14 and in the second axial range via the second housing member 16) and outer radial range. The inner radial range of the motor chamber 28 is partially defined by both the first and second housing members 14 and 16, and is further connected to the pump chamber 46 via openings 70, 72, 74, and 76 in the housing members 14 and 16, as described in more detail below.

[0023] like Figure 4 As shown, pump 44 is an internal gear pump (cycloidal pump). In other embodiments, the pump may be, for example, a vacuum pump, a radial pump, or an axial piston pump. As shown, the internal gear pump 44 includes an external gear 58, which is driven by the motor 30 when the motor 30 is actuated. Figure 5 In the embodiment shown, rotor 32 is coupled to external gear 58 such that rotation of rotor 32 causes similar rotation of external gear 58. External gear 58 rotates relative to internal gear 56, which is axially offset from the center of external gear 58. Gear pump crescent body 60 is fixed relative to gears 56, 58 to maintain the offset arrangement of gears 56, 58, as... Figure 4 As shown in the figure. Furthermore, the internal gear 56 is mounted or integrally formed on the shaft 78 located in the recess of the housing 12 to fix the axial and radial position of the internal gear 56 relative to the housing 12.

[0024] Pump inlet 52 supplies fluid from within pump chamber 46 to gears 56, 58 for discharge. More specifically, fluid enters the electro-hydraulic machine 10 via unit inlet 18 and passes through the low-pressure chamber 48 of pump chamber 46 to reach pump inlet 52 for discharge. Pump outlet 54 supplies fluid discharged by pump 44 to pump chamber 46, and more specifically to the high-pressure chamber 50 of pump chamber 46. The discharged fluid within high-pressure chamber 50 is directed to unit outlet 20.

[0025] Therefore, when the motor 30 is actuated, the external gear 58 rotates relative to the internal gear 56, thereby drawing fluid from the low-pressure chamber 48 through the pump inlet 52. A fixed volume of fluid is confined within the meshing teeth of gears 56 and 58. As the internal gear 56 radially deflects from the external gear 58, the fluid is discharged as the volume between the meshing teeth decreases until the fluid exits through the pump outlet 54 and reaches the high-pressure chamber 48. The operating principle of the external gear pump unit is similar to that described above for the internal gear pump 44.

[0026] For axial piston pumps, when the electric motor is actuated, the rotary cylinder rotates, which in turn allows multiple pistons to discharge along the surface of the swashplate. Depending on the angular position of the swashplate, the pistons discharge a specific amount of fluid from the low-pressure port to the high-pressure port of the unit. For vane pumps, when the electric motor is actuated, the vane housing allows multiple vanes to discharge fluid between the low-pressure port and the high-pressure port.

[0027] like Figure 5 As shown, first and second gears 56, 58 are mounted to a second housing member 16 for rotation relative to the second housing member 16. A shaft 78 is supported by two housings 14, 16, supported at a first axial end by the first housing member 14 and at a second axial end by the second housing member 16, wherein the internal gear 56 is mounted to the shaft 78 between the first and second axial ends. Journal bearings 62, 64 are located between the housing member 16 and the gears 56, 58 (including the integrated shaft 78) to position the gears 56, 58 relative to the housing member 16 and further facilitate smooth rotation of the gears 56, 58 relative to the housing member 16. The first journal bearing 62 is located between the shaft 78 of the internal gear 56 and a recess in which the shaft 78 is received, such that the first journal bearing 62 surrounds a portion of the shaft 78. The second journal bearing 64 is located between the external gear 58 and the housing member 16. More specifically, the external gear 58 is a cup-shaped external gear surrounding a portion of the housing member 16, such that the external gear 58 is mounted on the radially outward surface of the second journal bearing 64 to surround the second journal bearing 64.

[0028] Continue to refer to Figure 5The housing 12 includes a plurality of radial cooling channels 70, 72, 74, 76 that interconnect the motor chamber 28 to the pump chamber 46 and allow pumped fluid to pass between the two chambers 28, 46. Since the pump chamber 46 is nested within the motor chamber 28, each of the radial cooling channels extends radially outward from the pump chamber 46 to the motor chamber 28.

[0029] A first low-pressure radial cooling channel 70 extends from the low-pressure pump chamber 48 through the first housing member 14 to the motor chamber 28. The first low-pressure radial cooling channel 70 is axially positioned between the unit inlet 18 and the pump inlet 52. A second low-pressure radial cooling channel 72 extends from the low-pressure pump chamber 48 through the second housing member 16 to the motor chamber 28. The second low-pressure radial cooling channel 72 is axially positioned opposite the first low-pressure radial cooling channel 72, such that the pump inlet 52 is axially positioned between the two low-pressure radial cooling channels 70 and 72.

[0030] Housing 12 includes similar high-pressure radial cooling channels or recirculation channels 74, 76, located in the respective housings 14, 16 and extending radially between the high-pressure pump chamber 50 and the motor chamber 28. A first high-pressure radial cooling channel 74 is axially positioned between the pump outlet 54 and the unit outlet 20, and a second high-pressure radial cooling channel 76 is positioned opposite to the first high-pressure radial cooling channel 74, such that the pump outlet 54 is axially positioned between the two high-pressure radial cooling channels 74, 76.

[0031] The diameters of the low-pressure radial cooling channels 70 and 72 are larger than those of the high-pressure radial cooling channels 74 and 76, thereby allowing a larger amount of fluid to reach the motor chamber 28 via the low-pressure radial cooling channels 70 and 72. This addresses the increased pressure of the fluid entering the motor chamber 28 via the high-pressure radial cooling channels 74 and 76, and further avoids significantly reducing the pressure of the fluid leaving the unit outlet 20.

[0032] Figure 6 The diagram illustrates a cross-section of the electro-hydraulic machine 10 and includes arrows indicating different flow paths from unit inlet 18 to unit outlet 20. A first flow path 104 (dashed line) extends from unit inlet 18 into low-pressure chamber 48 between unit inlet 18 and pump inlet 52. First flow path 104 continues through pump 44 (passing through pump inlet 52 to pump outlet 54), thereby pressurizing the fluid passing through it. First flow path 104 then continues from pump outlet 54 to unit outlet 20.

[0033] Low-pressure chamber 48 Figure 6 The diagram shows the front portion 48A of a low-pressure chamber 48 located between unit inlet 18 and pump inlet 52 / gears 56, 58. The rear portion 48B of the low-pressure chamber 48 extends axially from the rear of the chamber 48 between pump inlet 52 / gears 56, 58. Similarly, the high-pressure chamber 50... Figure 6 The diagram shows a front portion 50A between the pump outlet 54 and the unit outlet 20, and a rear portion 50B between the pump outlet 54 and the rear axial range of the chamber 50.

[0034] A motor cooling passage, or second flow path 106, extends from unit inlet 18 to low-pressure chamber 48 between unit inlet 18 and pump inlet 52. Within low-pressure chamber 48, the second flow path 106 deviates from the first flow path 104. Instead of continuing to pump inlet 52, the second flow path 106 extends radially outward / diversifies through a first low-pressure radial cooling channel 70 to enter motor chamber 28. Within motor chamber 28, pumped fluid cools motor 30. The second flow path 106 continues axially through motor chamber 28. As shown, stator 34 includes an axial bore 36 through which pumped fluid can flow along the second flow path 106 to cool motor 30. Additional fluid can flow between rotor 32 and stator 34 and otherwise axially through motor housing 28. The second flow path 106 continues radially inward from motor chamber 28 back to low-pressure chamber 48 via a second low-pressure radial cooling channel 72. The second low-pressure radial cooling channel 72 guides the second flow path 106 to the rear side of the low-pressure chamber 48, so that the second flow path 106 has effectively axially bypassed the pump inlet 52. From here, the second flow path 106 continues through the pump 44 (through the pump inlet 52 to the pump outlet 54), thereby pressurizing the fluid passing through it. The second flow path 106 then continues from the pump outlet 54 to the unit outlet 18.

[0035] The second flow path 106 separates from the first flow path 104 at the junction JP in the low-pressure chamber 48 between the unit inlet 18 and the pump inlet 52. The second flow path 106 rejoins the first flow path 104 at the pump inlet 52. Together, both flow paths 104 and 106 supply fluid from the unit inlet 18, through the pump 44, and to the unit outlet 20, while also cooling the motor 30.

[0036] Figures 6-7 The diagram illustrates a recirculation path or third flow path 108 that routes the discharged fluid (discharged by pump 44) from the high-pressure chamber 50 back to the low-pressure chamber 48. For example... Figure 6 As shown, the fluid discharged from the high-pressure chamber 50 enters the motor chamber 28 via the third flow path 108 through the high-pressure radial cooling channels 74 and 76. Figure 7 As shown, the third flow path 108 travels through the motor chamber 28 to one or both of the first and second low-pressure radial cooling channels 70, 72, where the fluid returns to the low-pressure chamber 48. The pressure of the fluid from the high-pressure chamber 50 (i.e., along the third flow path 108) is greater than the pressure of the fluid from the low-pressure chamber 48 (i.e., along the second flow path 106), thereby promoting flow and preventing stagnation of the fluid within the motor chamber 28.

[0037] Figures 8-10 The diagram illustrates an axial stacking arrangement of individual electric and hydraulic machines 10A, 10B, and 10C used to form a single, larger electric and hydraulic machine 10'. The electric and hydraulic machines 10A, 10B, and 10C are modular and can be stacked to increase the outlet flow rate of machine 10'. Although Figures 8-10 The arrangement shown includes three electric and hydraulic machines 10A, 10B, and 10C, but fewer or more electric and hydraulic machines 10 can be stacked axially to suit the needs of a specific job or application. Figure 1 The housing 12' shown is modified to facilitate the stacking of machines 10A, 10B, and 10C, as follows: Figure 8 As shown, two identical housing portions 122 and two end cap housing portions 124 and 126, different from the two identical housing portions 122, together form housing 12'. Components of the first and second housing members 14 and 16 are assembled together in the identical housing portions 122. End cap housing portions 124 and 126 together support the axial end of shaft 78.

[0038] Each electro-hydraulic machine 10A, 10B, 10C in the stack includes its own pump 44 having a pump inlet 52 and a pump outlet 54. Further, each electro-hydraulic machine 10A, 10B, 10C includes its own motor 30 for driving the respective pump 44. In some embodiments, the pumps 44 are completely disengaged from each other, such that each pump 44 and its corresponding gear assemblies 56, 58 can operate independently of the operation of the other pumps 44 and gear assemblies 56, 58. In other embodiments, the shafts 78 of the respective internal gears 56 can be coupled together by means of a coupling mechanism 110. The coupling of the shafts 78 of the internal gears 56 forces the motors 30 to rotate synchronously, resulting in the use of a single inverter for all motors, and thus a reduction in cost, design complexity, and required space.

[0039] Furthermore, through the fixed connection of pump 44, pump 44 can be assembled such that hysteresis is introduced between its flow ripples. The result of hysteresis is flow ripples with a higher frequency and lower amplitude, which can reduce the cogging effect of the actuator, stress on components, and reduce overall noise.

[0040] Furthermore, the stacked architecture enables advanced control strategies that can be controlled via controller 120. Figure 10From an electronic perspective, under conditions of high flow rate and low pressure demand, one or more motors 30 can be deactivated, allowing the remaining motors 30 to operate closer to their peak efficiency. From a hydraulic perspective, a digital system can be implemented. When pumping against a high pressure differential, one or more of the pumps 44 can be disconnected from the main circuit and pumped directly to the tank or reservoir. This arrangement reduces the outlet flow rate and, additionally, reduces the torque applied to each motor 30, resulting in a potential reduction in the size of the motors 30.

[0041] like Figures 8-9 As shown, the low-pressure chambers 48 of the three machines 10A, 10B, and 10C are interconnected, forming a single larger low-pressure chamber 48'. Similarly, the high-pressure chambers 50 of the three machines 10A, 10B, and 10C are interconnected, forming a single larger high-pressure chamber 50'. The unit inlet 18' of machine 10' is the unit inlet 18 of the first electro-hydraulic machine 10A. To allow fluid to enter the low-pressure chamber 48 of the subsequent second electro-hydraulic machine 10B, the fluid passes through the unit inlet 18 of the first machine 10A, the low-pressure chamber 48 of the first machine 10A, and the unit inlet 18 of the second machine 10B. Likewise, to allow fluid to enter the low-pressure chamber 48 of the third machine 10C, the fluid is delivered to the low-pressure chamber 48 of the second machine 10B as described above and through the unit inlet 18 of the third machine 10C. The fluid is delivered to the low-pressure chamber 48 of each machine 10A, 10B, and 10C without first being discharged by any of the pumps 44 in machine 10'. Although some previously discharged fluids can be referenced as above. Figures 6-7 The fluid reaches the low-pressure chamber 48 via the recirculation passage 108, but the low-pressure chamber 48 is additionally arranged to receive fluid that has not yet been discharged by any pump 44.

[0042] The high-pressure chambers 50 of the three machines 10A, 10B, and 10C are generally similar in arrangement and interconnection to the low-pressure chamber 48 described above. The high-pressure chambers of machines 10A, 10B, and 10C are interconnected, forming a single, larger high-pressure chamber 50'. The unit outlet 20' of machine 10' is the unit outlet 20 of the first machine 10A. To allow fluid to reach the unit outlet 20', the fluid passes axially through any of the high-pressure chambers 50 located between them. For example, fluid from the third machine 10C travels from the high-pressure chamber 50 of the third machine 10C, through the unit outlet 20 of the third machine 10C, into the high-pressure chamber 50 of the second machine 10B, through the unit outlet of the second machine 10B, into the high-pressure chamber 50 of the first machine 10A, and through the unit outlet 20'.

[0043] like Figure 9As shown, low-pressure radial cooling channels 70, 72 and motor chamber 28 are provided via a second flow path 106 for moving fluid from the first machine 10A to the second machine 10B and from the second machine 10B to the third machine 10C. Furthermore, this arrangement provides cooling for all motors 30 in machine 10'.

[0044] Therefore, the modular electric and hydraulic machines 10', including machines 10A, 10B, and 10C, are not connected in series because machines 10A, 10B, and 10C do not transfer the output of one pump to the inlet of the next pump. Instead, the pumps operate in parallel, condensed into a single machine 10', and share a low-pressure chamber and a high-pressure chamber 48', 50'.

[0045] The various features of this disclosure are set forth in the appended claims.

Claims

1. An electric and hydraulic machine comprising: a housing defining a motor chamber and a pump chamber; a motor including a rotor and a stator positioned within the motor chamber; a pump including a pumping element positioned within the pump chamber, the pumping element movable by the motor to expel fluid in the pump chamber, the pump chamber including a low pressure chamber and a high pressure chamber, a unit inlet defined by the housing and in communication with the low pressure chamber, and a unit outlet defined by the housing and in communication with the high pressure chamber, the pump chamber positioned radially inward of the motor chamber such that the pump is nested within the motor; and a radial cooling passage extending in a radial direction from the low pressure chamber to the motor chamber such that fluid in the pump chamber is in communication with the rotor and the stator to cool the motor.

2. The electric and hydraulic machine of claim 1, wherein the motor includes a first axial extent and a second axial extent opposite the first axial extent, and wherein the pumping element is fully nested within the motor.

3. The electric and hydraulic machine of claim 1, wherein the radial cooling passage is a first radial cooling passage, the electric and hydraulic machine further comprising a second radial cooling passage extending radially from the low pressure chamber to the motor chamber, wherein the first radial cooling passage is positioned axially to a first side of the pumping element, and wherein the second radial cooling passage is positioned axially to a second side of the pumping element opposite the first side.

4. The electric and hydraulic machine of claim 1, wherein the radial cooling passage is a low pressure radial cooling passage, the electric and hydraulic machine further comprising a high pressure radial cooling passage extending from the high pressure chamber to the motor chamber.

5. The electric and hydraulic machine of claim 4, wherein the high pressure radial cooling passage has a smaller cross section than the low pressure radial cooling passage.

6. The electric and hydraulic machine of claim 1, wherein the radial cooling passage defines a portion of a motor cooling passageway, wherein the stator includes a plurality of axial stator holes, and wherein the plurality of axial stator holes define a portion of the motor cooling passageway.

7. The electric and hydraulic machine of claim 6, wherein the motor cooling passageway is fully defined within the housing and extends from the low pressure chamber through the motor chamber and to the low pressure chamber.

8. The electric and hydraulic machine of claim 1, wherein the radial cooling passage extends radially outward from the pump chamber to the motor chamber.

9. The electric and hydraulic machine of claim 1, wherein the rotor is fixed to the pumping element such that the motor is directly coupled to the pump.

10. The electro-hydraulic machine of claim 1, wherein the pump is a first pump and the motor is a first motor, the electro-hydraulic machine further comprising a second pump similar to the first pump and a second motor similar to the first motor, wherein the second pump and the second motor are axially aligned with the first pump and first motor, respectively, wherein the low pressure chamber of the first pump is in fluid communication with a low pressure chamber of the second pump such that the radial cooling passage is in fluid communication with a radial cooling passage extending from the low pressure chamber of the second pump to the motor chamber of the second motor in a radial direction.

11. A method of operating an electro-hydraulic machine, the method comprising: providing working fluid to a low pressure chamber of a pump via an inlet of the pump; actuating a motor within a housing, the motor being located within a motor chamber defined by the housing; driving the pump with the motor to expel the working fluid from the low pressure chamber; providing the working fluid expelled by the pump to an outlet of the pump; and cooling the motor with the working fluid by directing a first portion of the working fluid from the low pressure chamber to the motor chamber through a radial cooling passage.

12. The method of claim 11, wherein the radial cooling passage is a first radial cooling passage, the method further comprising returning the first portion of the working fluid from the motor chamber to the low pressure chamber via a second radial cooling passage.

13. The method of claim 11, wherein cooling the motor with the working fluid comprises directing the working fluid through axial stator holes in a stator of the motor.

14. The method of claim 11, wherein the radial cooling passage is a low pressure radial cooling passage, the method further comprising cooling the motor with the working fluid by directing a second portion of the working fluid from a high pressure chamber to the motor chamber through a high pressure radial cooling passage.

15. The method of claim 14, further comprising recirculating the second portion of the working fluid from the high pressure radial cooling passage through the motor chamber and to the low pressure radial cooling passage.

16. An electro-hydraulic machine comprising: a housing defining a motor chamber and a pump chamber; a motor comprising a rotor and a stator positioned within the motor chamber; a pump comprising a pumping element positioned within the pump chamber, the pumping element being movable by the motor to expel fluid in the pump chamber, the pump chamber comprising a low pressure chamber and a high pressure chamber, a unit inlet defined by the housing and in communication with the low pressure chamber, and a unit outlet defined by the housing and in communication with the high pressure chamber, the pump chamber being positioned radially inward of the motor chamber such that the pump is nested within the motor; a first flow path for working fluid of the pump, the first flow path extending from the low pressure chamber to the pumping element, to the high pressure chamber, and to the unit outlet; and a second flow path for working fluid of the pump, the second flow path extending from the high pressure chamber to the unit outlet. ​ a second flow path for working fluid of the pump, the second flow path extending from the low pressure chamber, through a radial cooling passage extending radially outward from the low pressure chamber, and into the motor chamber.

17. The electro-hydraulic machine of claim 16, wherein the radial cooling passage is a first radial cooling passage extending radially from the low pressure chamber to the motor chamber, the electro-hydraulic machine further comprising a second radial cooling passage extending radially from the motor chamber to the low pressure chamber, wherein the second flow path further extends from the motor chamber, through the second radial cooling passage, and into the low pressure chamber.

18. The electro-hydraulic machine of claim 16, wherein the stator includes a plurality of axial stator holes, and wherein the second flow path extends through the plurality of axial stator holes.

19. The electro-hydraulic machine of claim 16, wherein the second flow path is entirely defined within the housing.

20. The electro-hydraulic machine of claim 16, wherein the pump is a first pump and the motor is a first motor, the electro-hydraulic machine further comprising a second pump similar to the first pump and a second motor similar to the first motor, wherein the second pump and the second motor are axially aligned with the first pump and first motor, respectively, wherein the second flow path is configured to provide fluid to a low pressure chamber of the second pump.

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