BACKGROUND
The present invention relates generally to the field of electrically driven hydraulic pumps, commonly referred to as ePumps. Specifically, the present invention relates to the field of integrated electro-hydraulic units having internal position sensors.
SUMMARY
The present invention provides, in one aspect, an integrated electro-hydraulic unit including a hydraulic machine, an electric machine, a position sensor, and a shared housing enclosing the hydraulic machine, the electric machine, and the position sensor. The hydraulic machine has a rotary working group configured to pump a working fluid. The rotary working group has a shaft. The electric machine includes an electric machine stator and an electric machine rotor which is driven by an electric field produced by the stator and which drives the shaft of the rotary working group. The position sensor is at least partially positioned on the shaft and configured to sense a positional characteristic of the shaft.
The present invention provides, in another aspect, an integrated electro-hydraulic unit including a hydraulic machine, an electric machine encircling the hydraulic machine, a position sensor, and a housing at least partially surrounding the hydraulic machine and the electric machine. The hydraulic machine includes a rotary working group configured to pump a working fluid. The rotary working group has a shaft which defines a rotational axis and a bearing which supports the shaft. The electric machine includes an electric machine stator and an electric machine rotor which is driven by an electric field produced by the stator and which drives the shaft of the rotary working group. The position sensor is at least partially positioned on the shaft and is configured to sense a positional characteristic of the shaft. Along the rotational axis, the position sensor is positioned between the bearing and a portion of the housing.
The present invention provides, in another aspect, an integrated electro-hydraulic unit including a hydraulic machine, an electric machine encircling the hydraulic machine, a position sensor, and a housing at least partially surrounding the hydraulic machine and the electric machine. The hydraulic machine includes a rotary working group configured to pump a working fluid. The rotary working group has a shaft defining a rotational axis. The electric machine includes an electric machine stator and an electric machine rotor which is driven by an electric field produced by the stator and which drives the shaft of the rotary working group. The position sensor is at least partially positioned on the shaft and is configured to sense a positional characteristic of the shaft. The housing at least partially surrounds the hydraulic machine and the electric machine. The housing defines a first axial end and a second axial end opposite the first axial end. The second axial end is spaced from the first axial end along the rotational axis. The position sensor is positioned between the first axial end and the second axial end of the housing.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of an integrated electro-hydraulic unit.
FIG. 2 is a rear perspective view of the integrated electro-hydraulic unit of FIG. 1.
FIG. 3 is a top cross-section of the integrated electro-hydraulic unit taken along line 3-3 of FIG. 1.
FIG. 4 is a side cross-section of the integrated electro-hydraulic unit taken along line 4-4 of FIG. 1.
FIG. 5 is an enlarged cross-section view of the integrated electro-hydraulic unit taken along line 4-4 of FIG. 1.
FIG. 6 is an exploded view of a shaft and a cylinder block of the integrated electro-hydraulic unit of FIG. 1.
FIG. 7 is a perspective view of a valve plate of the integrated electro-hydraulic unit of FIG. 1.
FIG. 8 is a perspective view of a positional sensor of the integrated electro-hydraulic unit of FIG. 1.
FIG. 9 is an exploded view of the positional sensor of the integrated electro-hydraulic unit of FIG. 1.
DETAILED DESCRIPTION
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
A plurality of hardware and software based devices, as well as a plurality of different structural components may be used to implement various embodiments. In addition, embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software (for example, stored on non-transitory computer-readable medium) executable by one or more processors.
FIGS. 1-4 illustrate an integrated electro-hydraulic unit 10 according to one construction of the present disclosure. The integrated electro-hydraulic unit 10 includes an electric machine 14, a hydraulic machine 18, and a housing 22 as illustrated in FIGS. 3 and 4. The integrated electro-hydraulic unit 10 further includes an electrical connector 26, a position sensor 30, and a controller 34. The integrated electro-hydraulic unit 10 integrates the electric machine 14 and the hydraulic machine 18 such that they can interchangeably transfer mechanical power into fluid power known as pumping. In addition to pumping, the integrated electro-hydraulic unit 10 can also transfer the fluid power into mechanical power. In other words, the hydraulic machine, or “pump,” has the capability of pumping, but also the capability of motoring. The capability of switching between pumping and motoring is possible by reversing a rotational direction of the electric machine 14. A unit capable of pumping and motoring is commonly referred to as a two-quadrant unit in the art. In some constructions, the integrated electro-hydraulic unit 10 may include an additional integrated electro-hydraulic unit having a housing separate from the integrated electro-hydraulic unit 10. In other constructions, multiple electro-hydraulic units may share the same housing 22. In some constructions, multiple electro-hydraulic units can be stacked together on a common shaft. Stacked electro-hydraulic units work with a single inverter.
With reference to FIGS. 1 and 2, the housing 22 includes a housing shell 38, or radial casing, an axial front casing 42, or swashplate end case, and an axial end casing 46, or porting end case. In some constructions, the axial front casing 42 may be a separate piece from the housing shell 38 and the axial end casing 46. In some constructions, the axial front casing 42 may be integral with the housing shell 38. In some constructions, the axial end casing 46 may be a separate piece from the housing shell 38 and the axial front casing 42. In some constructions, the axial end casing 46 may be integral with the housing shell 38. In some constructions, the housing 22 may be formed as one-singular piece. The axial front casing 42 defines a first axial end 50 of the housing 22 and the axial end casing 46 defines a second axial end 52 of the housing 22 opposite from the first axial end 50. The first axial end 50 and the second axial end 52 are spaced apart from each other along a shared rotational, or central, axis A1 of the electric machine 14 and the hydraulic machine 18.
In the illustrated embodiment, the housing shell 38 is sandwiched between the axial front casing 42 and the axial end casing 46. Tie rods 56 extend transverse to the axial front casing 42 and axial end casing 46 and parallel to the shared rotational, or central, axis A1 of the electric machine 14 and the hydraulic machine 18. The tie rods 56 secure the axial front casing 42 and the axial end casing 46 to each other with the housing shell 38 therebetween. The housing shell 38, the axial front casing 42 and the axial end casing 46 form a singular shared interior cavity for the positional sensor 30, the electric machine 14 and the hydraulic machine 18, as discussed in further detail below. Specifically, the housing 22 collectively surrounds the electric machine 14, the hydraulic machine 18 and the positional sensor 30. In other words, rather than having the electric machine 14, the hydraulic machine 18 and the positional sensor 30 in individual, separate housings, the electric machine 14, the hydraulic machine 18, and the positional sensor 30 share the common, or collective, housing 22. The housing 22 may be coupled to a bracket 60 via fasteners 64 on the axial front casing 42 and the axial end casing 46. In some constructions, the housing 22 may be coupled to a plurality of brackets via the fasteners 64 on the axial front casing 42 and the axial end casing 46.
As shown in FIGS. 1-4, the housing shell 26 is a hollow cylinder. The axial front casing 42 has an electrical connection aperture 68 (see FIG. 4) and a plurality of drain ports 72. In other constructions, the axial front casing 42 may include only one drain port 72. In some constructions, the housing shell 26 may include the drain ports or the single drain port. The electrical connection aperture 68 accommodates the routing of wiring 76, such as cables or wires, to the electric machine 14. Specifically, the electrical connection aperture 68 allows the wiring 76 to run between the electrical connector 26 and the electric machine 14. The electrical connector 26 electrically couples the electric machine 14 to a power source. The wiring 76 provides power to the electric machine 14. The electrical connection aperture 68 also accommodates the routing of wiring 80 of the position sensor 30. Specifically, the electrical connection aperture 50 allows the wiring 80 to run between the electrical connector 26 and the position sensor 30.
With reference to FIGS. 1, 3 and 4, the axial front casing 42 includes an axial front plate 84 and a projection 88 extending from the axial front plate 84. In some constructions, the axial front casing 42 may be formed in its entirety as a single piece. The front axial plate 84 has the drain ports 72 and the electrical connection aperture 76. The axial front plate 84 is disk-shaped. The axial front plate 84 defines the first axial end 50. The axial front plate 84 extends radially outward from the projection 88. The projection 88 projects axially from the axial front plate 84 (e.g., projects axially from the axial front plate 84 toward the axial end casing 46). As illustrated in FIG. 3, the projection 88 extends into the cavity defined by the housing shell 38. The projection 88 has a distal end 92 opposite from the axial front plate 84. The axial front casing 42 includes a recess 96 in the projection 88. As illustrated, the recess 96 extends axially into the projection 88 from the distal end 90. The recess 96 receives the position sensor 30. As shown in FIGS. 3-5, The axial front casing 42 defines an internal surface 97 facing the axial end casing 46. The internal surface 97 partially defines the recess 96 and is parallel to the first axial end 50. The internal surface 97 is inward from an outer perimeter of the housing 22 and faces the interior cavity of the housing 22.
With reference to FIGS. 1, 3 and 4, the axial end casing 46 includes an axial end plate 86 and a protrusion 90 extending from the axial end plate 86. In some constructions, the axial end casing 46 may be formed in its entirety as a single piece. The axial end plate 86 is disk-shaped. The axial end plate 86 defines the second axial end 52. The axial end plate 86 extends radially outward from the protrusion 90. The protrusion 90 projects axially from the axial end plate 86 (e.g., projects axially from the axial end plate 86 toward the axial front casing 42). As illustrated in FIG. 3, the protrusion 90 extends into the cavity defined by the housing shell 38. The protrusion 90 has a distal end 94 opposite from the axial end plate 86. The axial end casing 46 includes a recess 98 in the protrusion 90. As illustrated, the recess 98 extends axially into the protrusion 90 from the distal end 94.
As illustrated in FIGS. 2 and 3, the axial end casing 46 includes a first fluid opening 99 and a second fluid opening 101. The first fluid opening 99 is an inlet, and the second fluid opening 101 is an outlet, in a configuration in which the electric machine 14 powers the hydraulic machine 18 as a pump. The housing 22 fluidly seals the electric machine 14 and the hydraulic machine 18. In one embodiment, the first opening 99, the second opening 101, and the drain ports 72 are the only locations where the working fluid can enter and leave the housing 22.
As shown in FIGS. 3 and 4, the hydraulic machine 18 is nested within the electric machine 14 such that the electric machine 14 encircles the hydraulic machine 18. The electric machine 14 can be a motor of any suitable topology including, but not limited to, induction, surface permanent magnet, internal permanent magnet, wound rotor, and switched reluctance. The electric machine 14 includes a rotor 102 and a stator 106 with a winding. The stator 106 is located most proximal to the housing shell 38 of the housing 22. The rotor 102 is located radially inward towards the axis A1 from the stator 106. Both the rotor 102 and the stator 106 encircle the hydraulic machine 18.
As illustrated in FIGS. 3-5, the hydraulic machine 18 may be an axial piston machine of swashplate type. In other constructions, the hydraulic machine 18 can be a bent axis pump, which operates on the same principles but lacks a movable swashplate. The hydraulic machine 18 includes a rotary working group 110 which operates on the working fluid. The rotary group 110 includes a cylinder block 114, a shaft 118, a drive flange 122, a swashplate 126, a plurality of pistons 130, a plurality of slippers 134, a retaining plate 138 and a valve plate 142. The cylinder block 114 is rotatably supported by the shaft 118 about the axis A1. The cylinder block 114 is coupled to the shaft 118 such that the cylinder block 114 and the shaft 118 are locked together in rotation about the axis A1. Specifically, the angular speed, the degree of rotation, and the change in degree of rotation of the cylinder block 114 are equal to the angular speed, the degree of rotation, and the change in degree of rotation of the shaft 118. In the illustrated construction, the cylinder block 114 is coupled to the shaft 118 via a spline connection. As shown in FIG. 6, the cylinder block 114 includes a plurality of grooves 115 which mesh with a plurality of splines 116 on the shaft 118. In some constructions, the cylinder block 114 may be locked to the shaft 118 in a different manner (e.g., via a key and keyway, or other non-circular interface).
Referring back to FIGS. 3-5, the shaft 118 is rotatably supported on first and second bearings 146, 147. The shaft 118 has a first end 119 supported on the first bearing 146, and a second end 120 opposite the first end 119 and supported on the second bearing 147. The cylinder block 114 is rotatable about the axis A1 in a first rotational direction. The cylinder block 114 has a first end 150 proximal to the axial front casing 42 and a second end 154 proximal to the axial end casing 46. The second end 154 includes a plurality of slots 158 circumferentially located around the axis A1. Each of the slots 158 is identical in shape. The drive flange 122 is located between the cylinder block 114 and the rotor 102 and rotatably couples the cylinder block 114 to the rotor 102. The swashplate 126 is located along the axis A1 and is in contact with the plurality of slippers 134 towards the first end 150 of the cylinder block 114. The plurality of pistons 130 are received in the cylinder block 114 radially around the axis A1. The valve plate 142 is located along the axis A1 and between the second end 154 of the cylinder block 114 and axial end casing 46, as best shown in FIG. 4.
As shown in FIG. 7, the valve plate 142 includes a first port 143 and a plurality of second ports 144. In some constructions, the plurality of second ports 144 may be combined to form a single second port. In some constructions, the valve plate 142 may include a third port in fluid communication with a cooling pipe. With reference to FIG. 3, the valve plate 142 is sandwiched between the second end 154 of the cylinder block 114 and the axial end casing 46. The first port 143 is in fluid communication with the first fluid opening 99 of the axial end casing 46 and with the plurality of slots 158 of the cylinder block 114. The second port 144 is in fluid communication with the second fluid opening 101 of the axial end casing 46 and with the plurality of slots 158 of the cylinder block 114.
With reference to FIG. 5, during movement in the first rotational direction of the cylinder block 114, each of the plurality of pistons 130 move in a reciprocating movement from the second end 154 of the cylinder block 114, known as a top dead center, towards the first end 150 of the cylinder block 114, known as the bottom dead center. As each of the plurality of pistons 130 moves away from the top dead center towards the bottom dead center, each of the plurality of pistons 130 pulls the working fluid through the first port 143 and into the cylinder block 114. As each of the plurality of pistons 130 moves away from the bottom dead center and towards the top dead center, each of the plurality of pistons 130 pushes the working fluid out of the cylinder block 114. In some constructions, all of the pumped working fluid is pushed out of the rotary working group 110 through the second ports 144. In other constructions, a first portion of the pumped working fluid is pushed out of the rotary working group 110 through the second ports 144, and a second portion of the pumped working fluid, a cooling flow, is pushed out of the rotary working group 110 through a third port of the valve plate 142, separate from the first portion at the second ports 144 (e.g., not mixed or conjoined together therewith).
With reference to FIGS. 3-5, the first bearing 146 is positioned in the recess 96 of the axial front casing 42 and is mounted to the axial front casing 42. Specifically, the first bearing 146 is supported by the projection 88. Further, the first end 119 of the shaft 118 is positioned in the recess 96 of the axial front casing 42. The internal surface 97 of the axial front casing 42 faces the shaft 118 and the first bearings 146. Along the axis A1, the position sensor 30 is positioned between the first bearing 146 and a portion of the axial front casing 42. Specifically, the position sensor 30 is positioned between the first bearing 146 and the internal surface 97 of the axial front casing 42. Further, along the axis A1, the position sensor 30 is positioned between the first axial end 50 and the first bearing 146. As such, there is no position sensor located axially inboard of the first bearing 146 (i.e., between the first and second bearings 146, 147). The first bearing 146 can be positioned directly adjacent the swashplate 126. As a result, the first bearing 146 is positioned closer to the second bearing 147 to increase resistance to bending of the shaft 118. The second bearing 147 is positioned in the recess 98 of the axial end casing 46 and is mounted to the axial end casing 46. Specifically, the second bearing 147 is supported by the protrusion 90. Further, the second end 120 of the shaft 118 is positioned in the recess 98 of the axial end casing 46.
With reference to FIGS. 3 and 4, the shaft 118 is positioned between the first axial end 50 and the second axial end 52. The position sensor 30 is positioned between the first axial end 50 and the second axial end 52. Specifically, the position sensor 30 and the shaft 118 are enclosed by the housing 22. Because the shaft 118 does not extend outside of the housing 22, the shaft 118 does not need to be sealed to the housing 22. As a result, the maximum pressure of the housing 22 is not limited by a shaft sealing. Accordingly, the housing 22 may reach a pressure above 3-5 bar. For example, the housing 22 may reach a pressure of up to 10 bar. Because the housing 22 can withstand a higher pressure than a conventional housing with a shaft sealing, the integrated electro-hydraulic unit 10 may be used in higher-pressure, closed-circuit systems. Further, due to the increased maximum pressure of the housing 22, the lifetime of the electro-hydraulic unit 10 is increased, and the robustness of the electro-hydraulic unit 10 to the environment is improved.
Referring to FIGS. 8 and 9, the position sensor 30 includes a fixed, or static, portion 162 and a movable, or rotating, portion 166. The position sensor 30 is configured to sense a positional characteristic of the shaft 118. The positional characteristic may be an angular speed, a degree of rotation, and/or a change in degree of rotation. In the illustrated construction, the position sensor 30 is a resolver. In some constructions, the position sensor may be a transmitter resolver, a receiver resolver, or a differential resolver. In some constructions, the position sensor 30 may be a rotary or shaft encoder. Specifically, the position sensor 30 may be an absolute encoder or an incremental encoder. The position sensor 30 may be a digital device or an analog device.
With continued reference to FIGS. 8 and 9, the fixed portion 162 is a stator and the movable portion 166 is a rotor. The fixed portion 162 has a primary winding and a plurality of secondary windings (e.g., sine and cosine windings). In some constructions, the fixed portion may be a light source, a photodetector, and/or an electronics board. In some constructions, the fixed portion may be a plurality of electrical contacts. In some constructions, the fixed portion may be a magnetoresistive or Hall-effect sensor. In some constructions, the movable portion may be a code disk or a plurality of code disks. In some constructions, the movable portion may be a circular magnet. The fixed portion 162 and the movable portion 166 are each shaped as hollow cylinders. The fixed portion 162 defines an opening 170 which receives the movable portion 166. The movable portion 166 defines an opening 174 which receives the shaft 118.
Referring to FIG. 5, the movable portion 166 is mounted on the shaft 118 such that the movable portion 166 rotates with the shaft 118 about the axis A1. Specifically, the movable portion 166 is mounted on the first end 119 of the shaft 118. As a result, the movable portion 166 is rotatable relative to the housing 22 and relative to the fixed portion 162. As illustrated, the fixed portion 162 is mounted on, or supported by, the projection 88 of the front axial casing 42. As a result, the fixed portion 162 is fixed relative to the housing 22.
As illustrated in FIGS. 3 and 4, the fixed portion 162 includes, or is coupled to, the wiring 80 which extends to the electric connector 26. The wiring 80 of the position sensor 30 may be connected to control pins of the electric connector 26. The wiring 80 of the position sensor 30 may be sealed with the electric connector 26 and may not require separate sealing. Further, the electric connector 26 is electrically coupled to the controller 34 such that the position sensor 30 is electrically coupled to the controller 34. In some constructions, the wiring 80 may connect directly to the controller 34 rather than through the electric connector 26.
The wiring 80 transmits a signal from the position sensor 30 to the controller 34. In some constructions, the position sensor 30 may wirelessly transmit the signal to the controller 34. The transmitted signal may include the sensed positional characteristic of the shaft 118 (i.e., the angular speed, the degree of rotation, and/or the change in degree of rotation). In response to receiving the transmitted signal, the controller 34 may adjust operation of the electric machine 14. The controller 34 may also determine a second characteristic of the shaft 118 based on the sensed positional characteristic of the shaft 118 (e.g., the controller 34 may determine an angular speed of the shaft based on the sensed degree of rotation). The controller 34 may determine a positional characteristic of the cylinder block 114 based on the sensed positional characteristic of the shaft 118.
Patent Application
20250067256
