Patent Description:
In general, an electric oil pump (EOP) is a device that supplies oil to a hydraulic line of a transmission or a braking device of a vehicle using a motor, in which circulation of oil is necessary.

In the case of a hybrid electric vehicle (HEV), an engine is stopped when the vehicle is stopped and thus it is difficult to supply a constant pressure to a transmission through a mechanical oil pump. Therefore, the HEV employs an electric oil pump that supplies oil through a motor.

Such an electric oil pump includes a suction port and a discharge port through which oil moves.

However, in an electric oil pump of the related art, a phenomenon occurs in which flow rate performance decreases sharply at a high flow rate and a flow rate is not uniform during the movement of a fluid.

A motor is a device that converts electrical energy into mechanical energy to generate a turning force and has been widely used in vehicles, household appliances, industrial equipment, and the like.

The motor may include a housing, a shaft, a stator disposed on an inner circumferential surface of the housing, a rotor installed on an outer circumferential surface of the shaft, and the like. Here, the stator of the motor causes electrical interaction with the rotor to induce rotation of the rotor.

Here, the rotor may be classified into a surface-mounted permanent magnet (SPM) type and an interior permanent magnet (IPM) type according to a coupling structure of a magnet installed in the rotor core.

In an IPM type rotor, a magnet is inserted into a rotor core and thus magnetic flux density is lower than that of an SPM type rotor in which a magnet is exposed on a surface thereof, and therefore, dynamic characteristics of a motor having the IPM type rotor may be lower than those of a motor having the SPM type rotor.

In particular, when barriers are formed at both sides of the magnet in the IPM type rotor, an H-field indicating the magnitude of a magnetic flux is low at inner corners of the magnet. Accordingly, when a magnetization process is performed after assembly of the magnet, HS characteristics indicating the strength of a magnetic force may not be satisfied and thus full magnetization cannot be achieved. In addition, when the motor is operated at a high temperature, a risk of irreversible demagnetization may occur additionally.

When the H-field is increased to satisfy the HS characteristics of the magnet so as to solve the above problems, an overcurrent may be supplied and thus a magnetizer and a magnetization yoke may be degraded.

Therefore, there is a need for a rotor which achieves full saturated magnetization of a magnet only with a certain amount of current without applying an overcurrent.

Examples of electric pumps and motors according to the prior art are known from <CIT> and <CIT>.

An electric pump according to the present invention is claimed in claim <NUM>. An advantageous embodiment of the electric pump according to the present invention is claimed in claim <NUM>.

Embodiments are directed to providing an electric pump in which a shape of a suction port is changed to stabilize a flow of a fluid.

An electric pump capable of being detachably coupled with a bus bar through a fork-type terminal, not part of the present invention, is also disclosed.

An electric pump in which a motor housing and a connector unit are connectable at accurate positions, not part of the present invention, is also disclosed.

A motor in which barriers are formed on a rotor core to achieve full magnetization of a magnet, not part of the present invention, is also disclosed.

A motor in which an arrangement position of a barrier is determined by an arrangement angle and distance relative to a central point, not part of the present invention, is also disclosed.

An electric pump as disclosed includes a motor unit which includes a shaft, a rotor coupled to the shaft, and a stator disposed outside the rotor; a pump unit which includes a first rotor coupled to the motor unit and including a first lobe having gear teeth, and a second rotor disposed outside the first rotor and including a second lobe; and a second cover including a second surface on which the pump unit is disposed, wherein a second suction port and a second discharge port are disposed on the second surface, the second suction port provided on the second surface includes a third protrusion protruding toward an inner side of the second suction port, a first line connects the center of the first rotor and the center of the second rotor and a second line connects the center of the first rotor and a distal end of the third protrusion.

The first line passing through the center of the first rotor and the center of the second rotor is parallel to a third line connecting ends of the second suction port in a region adjacent to the third protrusion,
A distance between the first line and the second line is proportional to a distance between the center of the first rotor and the center of the second rotor.

A first cover is disposed between the motor unit and the pump unit, the first cover includes a first surface which accommodates the pump unit, the first surface includes a first suction port and a first discharge port, and the first suction port and the second suction port have different shapes.

The second cover may include an inlet which communicates with the second suction port and an outlet which communicates with the second discharge port.

According to an aspect not covered by the present invention, a third coupling hole may be formed in the center of the first rotor and engaged with the shaft, the shaft may have at least one cut surface, and the cut surface may match in shape with the third coupling hole.

According to an aspect not covered by the present invention, an electric pump as disclosed includes a motor unit including a shaft, a rotor provided with the shaft, a stator disposed outside the rotor, a bus bar disposed above the stator, and a motor housing which accommodates the rotor and the stator; and a connector unit disposed on the motor unit and including a power terminal coupled to a terminal of the bus bar, wherein the bus bar includes a bus bar terminal coupled with a coil wound around the stator or the rotor, and a bus bar body which insulates the bus bar terminal, an end of the power terminal diverges into a pair of contact portions, and the bus bar terminal is inserted between the contact portions to be electrically connected to the contact portions.

According to other aspects not covered by the present invention:
Divergence areas of the pair of contact portions may include a curved surface.

Each of the pair of contact portions may include a first region, a width of which increases at the divergence area; a second region which extends from the first region and a width of which decreases; and a third region which extends from the second region and a width of which increases, wherein a point at which the second region and the third region are connected to each other is in contact with the bus bar body.

The third region may include a curved surface.

The bus bar body may include a pair of first protrusions which guide the pair of contact portions.

The bus bar terminal may include a curved portion and be in surface contact with the pair of contact portions.

According to other aspects not covered by the present invention:
An electric pump as disclosed includes a motor unit including a shaft, a rotor coupled to the shaft, a stator disposed outside the rotor, and a motor housing which accommodates the rotor and the stator; and a connector unit disposed on the motor unit, wherein the motor unit includes at least one hole, and the connector unit includes at least one second protrusion inserted into the at least one hole.

An end portion of the motor housing may include a protrusion having a certain area, the connector unit may include a connector body and a connector connection part facing the protrusion, the protrusion may be provided with the at least one hole, and the connector connection part may be provided with the at least one second protrusion inserted into the at least one hole.

The connector connection part may be connected to a side of the connector body and include a first connection portion on which the at least one second protrusion is disposed and a second connection portion connected at a certain angle to the first connection portion.

The connector connection part may include a plurality of grooves arranged such that opposite sides thereof are symmetric to each other, and the at least one second protrusion may be provided between the plurality of grooves.

The connector connection part may include a rib formed in a lengthwise direction, and the at least one second protrusion may be provided on the rib.

The at least one second protrusion may be provided in a cylindrical shape, and an upper end thereof may be inclined along a circumference of the at least one second protrusion.

According to other aspects not covered by the present invention:
A motor as disclosed includes a shaft, a rotor including a hole in which the shaft is disposed, and a stator outside the rotor, wherein the rotor includes a rotor core and a magnet, the rotor core includes a main body, a pocket which is formed in the main body and in which the magnet is disposed, first barriers extending from both sides of the pocket, and second barriers formed between an inner circumferential surface of the main body and an outer circumferential surface of the main body, and a center (C11) of the second barrier has a certain arrangement angle θ in a circumferential direction from a first line (L11) passing through a center (CC) of the main body and a center of a width (W) of the magnet.

The arrangement angle θ may be calculated by the following equation: <MAT> wherein W represents a width of the magnet, D11 represents a distance from the center of the main body to an inner side surface of the magnet, and D22 represents a distance from the center of the main body to an outer side surface of the magnet.

The second barrier may have a certain radius (R).

The inner side surface of the magnet may be disposed on a second line (L22) passing through the center (CC) of the main body and the center (C11) of the second barrier.

An arrangement distance D33 from the center (CC) of the main body to the center (C11) of the second barrier may be calculated by the following equation: <MAT> wherein O represents a distance between one point (P1) on an outer circumferential surface of the second barrier disposed on the second line (L22) and one point P2 on the inner side surface of the magnet.

The second barrier may be formed to be long from an upper end of the main body to a lower end of the main body.

Two of the second barriers disposed to correspond to one magnet may be symmetrical to each other with respect to the first line (L11).

According to an embodiment, flow rate performance can be achieved even at a high flow rate.

Noise can be reduced by stabilizing the flow of a fluid.

Durability of a product can be increased by minimizing bubbles to be introduced into a region in which a fluid flows.

An additional process or structure for connecting a terminal and a bus bar of a motor can be skipped to reduce an assembly time and costs.

Components are replaceable by applying a detachable structure.

The reliability of assembly of a terminal and a bus bar may be secured using a position guide.

A connector unit can be connected at a designated position, thereby minimizing performance deviation for each product.

A manufacturing method can be simplified and process investment costs can be reduced by simplifying a shape of a motor housing for fixing a position.

In addition, in a motor as disclosed, a second barrier can be formed in a rotor to adjust magnetic flux saturation of a rotor core during magnetization of a magnet. Accordingly, when the same current is supplied for magnetization, full magnetization of the magnet can be achieved by allowing a maximum H field in a region of the magnet.

In this case, an arrangement position of the second barrier on the rotor core can be adjusted by an arrangement angle and distance.

Various and beneficial advantages and effects of the present invention are not limited to the above description and will be more easily understood in the course of describing specific embodiments of the present invention.

Various changes may be made in the present invention and various embodiments may be implemented, and certain embodiments will be illustrated in the drawings and described hereinafter. However, it should be understood that embodiments of the present invention are not limited to these embodiments and cover all modifications, equivalents, and alternatives falling within the idea and scope of embodiments.

As used herein, the terms "first," "second," etc. may be used herein to describe various elements but these elements are not limited by these terms. These terms are used only for the purpose of distinguishing one element from another. For example, a second element discussed below could be termed a first element without departing from the scope of embodiments. Similarly, a first element could be termed a second element. The terms "and/or" includes any one or any combination of a plurality of related listed items.

The terminology used herein is for the purpose of describing certain embodiments only and is not intended to be limiting of embodiments of the present invention. As used herein, the singular expressions are intended to include plural forms as well, unless the context clearly dictates otherwise. It will be understood that the terms "comprise" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, components, or a combination thereof but do not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, or a combination thereof.

When one element is referred to as being formed "on" or "under" another element in embodiments, it will be understood that the two elements are formed to be in direct contact with each other or to be in indirect contact with each other while one or more elements are interposed therebetween. The expression "on or under one element" should be understood to mean not only an upward direction but also a downward direction with respect to the element.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals regardless of figure number and will not be redundantly described.

<FIG> clearly illustrate only main features for conceptually clear understanding of the present invention, and thus, it is expected that various modifications may be made in the drawings and the scope of the present invention should not be limited by specific shapes shown in the drawings.

<FIG> is a perspective view of an electric pump as disclosed. <FIG> is an exploded perspective view of <FIG>.

Referring to <FIG> and <FIG>, the electric pump includes a motor unit <NUM>, a connector unit <NUM>, a first cover <NUM>, a pump unit <NUM>, and a second cover <NUM>.

The motor unit <NUM> generates power to transfer the power to the electric pump, and the connector unit <NUM> is provided on the motor unit <NUM> to supply the power to the motor unit <NUM>.

The connector unit <NUM> is provided on the motor unit <NUM> and may include a connector body <NUM> on a motor housing <NUM> and a connector connection part <NUM> connected to a side of the connector body <NUM>. A first through hole <NUM> may be provided, through which a shaft <NUM> of the motor unit <NUM> passes.

The first cover <NUM> is disposed between the connector unit <NUM> and the pump unit <NUM> and includes a second through hole <NUM> through which the shaft <NUM> of the motor unit <NUM> passes.

The pump unit <NUM> may be disposed between the first cover <NUM> and the second cover <NUM> and may be provided with a third through hole to which the shaft <NUM> passing through the first cover <NUM> is coupled.

The second cover <NUM> may be disposed on a front side of the pump unit <NUM> and combined with the first cover <NUM> to accommodate the pump unit <NUM>.

<FIG> is a diagram illustrating a structure of the motor unit <NUM> of <FIG>.

Referring to <FIG>, the motor unit <NUM> transmits power to the pump unit <NUM> and includes the shaft <NUM>, a rotor <NUM>, a stator <NUM>, a bus bar <NUM>, and a motor housing <NUM>.

The shaft <NUM> may be coupled to the rotor <NUM>. When power is supplied to cause electromagnetic interaction between the rotor <NUM> and the stator <NUM>, the rotor <NUM> rotates and the shaft <NUM> rotates in connection therewith. The shaft <NUM> may be supported by a bearing.

The rotor <NUM> is disposed inside the stator <NUM>. The rotor <NUM> may include a rotor core and a magnet coupled to the rotor core. The rotor <NUM> may be classified into the following types according to a coupling method of the rotor core and the magnet.

The rotor <NUM> may be embodied as a type in which the magnet is coupled to an outer circumferential surface of the rotor core. In this type of the rotor <NUM>, a separate can member may be coupled to the rotor core to prevent separation of the magnet and increase the coupling of the magnet. Alternatively, the magnet and the rotor core may be double injected and integrally formed.

The rotor <NUM> may embodied as a type in which the magnet is coupled to the inside of the rotor core. In this type of the rotor <NUM>, the inside of the rotor core may be provided with a pocket into which the magnet is inserted.

First, a rotor core may be formed by stacking a plurality of thin steel plates together. In this case, the rotor core may be formed as one piece that does not form a skew angle or as a form in which a plurality of unit cores forming a skew angle are combined together.

Secondly, a rotor core may be in the form of a single container. In this case, the rotor core may be formed as one piece that does not form a skew angle or as a form in which a plurality of unit cores forming a skew angle are combined together.

A magnet may be included inside or outside each of the unit cores.

The stator <NUM> causes electrical interaction with the rotor <NUM> to induce the rotation of the rotor <NUM>. A coil <NUM> may be wound around the stator <NUM> to cause interaction with the rotor <NUM>. A specific configuration of the stator <NUM> for winding a coil around the stator <NUM> will be described below.

The stator <NUM> may include a stator core with teeth. The stator core may be provided with a ring-shaped yoke and teeth may be provided on the yoke to face the center of the stator core. The teeth may be provided around the yoke at regular intervals. The stator core may be formed by stacking a plurality of thin steel plates together. Alternatively, the stator core may be formed by coupling or connecting a plurality of divided cores to each other.

The bus bar <NUM> may be disposed on an upper end of the stator <NUM> to be electrically connected to the coil <NUM>. The bus bar <NUM> may include a bus bar body <NUM> and a bus bar terminal <NUM>. The bus bar body <NUM> may be embodied as a ring-shaped mold member. The bus bar terminal <NUM> is connected to an end of the coil <NUM> lifted from an assembly of the stator <NUM> or an assembly of the rotor <NUM>.

The bus bar <NUM> may electrically connect coils <NUM> wound around the stator <NUM> or the rotor <NUM> to be electrically connected to U-, V-, or W-phase power terminals <NUM>.

The motor housing <NUM> may be formed in a cylindrical shape such that the stator <NUM> may be coupled to an inner wall thereof. An upper portion of the motor housing <NUM> may be open and a lower portion thereof may be closed. The lower portion of the motor housing <NUM> may be provided with a bearing mounting space for accommodating a bearing for supporting the lower portion of the shaft <NUM>.

<FIG> is a diagram illustrating a structure of the bus bar <NUM> of <FIG>.

The bus bar terminal <NUM> may be formed as an arc and include a plurality of connection terminals 143a to be coupled to the coil <NUM>. In one embodiment, three bus bar terminals <NUM> may be provided to electrically connect the coil <NUM> wound around the stator <NUM>, and each of the three bus bar terminals <NUM> may be delta-connected.

<FIG> is a diagram illustrating a structure of the connector unit <NUM> of <FIG>. <FIG> is a diagram illustrating an arrangement of the power terminals <NUM> included in the connector unit <NUM> of <FIG>.

Referring to <FIG> and <FIG>, the connector unit <NUM> may include a connector body <NUM> disposed on the motor unit <NUM> and a connector connection part <NUM> connected to a side of the body of the connector unit <NUM> to receive power.

The connector body <NUM> may be provided with the first through hole <NUM> through which the shaft <NUM> passes, and a region thereof may be inserted into the motor housing <NUM>. A sealing part may be provided at a side of the connector body <NUM> to maintain airtight coupling of the connector body <NUM> with the motor housing <NUM>.

A plurality of power terminals <NUM> may protrude outward from the connector body <NUM>. In one embodiment, three power terminals <NUM> may be provided to be each electrically connected to one of the bus bar terminals <NUM>.

The connector connection part <NUM> is connected to the connector body <NUM> and may receive external power. In one embodiment, the power terminals <NUM> protruding outward from the connector body <NUM> may be provided in a bent shape to pass through the connector body <NUM> and the connector connection part <NUM>. The shape of the power terminals <NUM> is not limited and may be variously changed according to the shape of the connector connection part <NUM> connected to the connector body <NUM>.

<FIG> is a diagram illustrating a structure in which the bus bar <NUM> and the power terminals <NUM> of <FIG> are connected to each other. <FIG> is a diagram illustrating a structure of an end portion of the power terminal <NUM> of <FIG>.

Referring to <FIG> and <FIG>, bus bar terminals <NUM> may be inserted into the power terminals <NUM> to be electrically connected to the power terminals <NUM>.

An end of each of the power terminals <NUM> may branch into a pair of contact portions <NUM>. Ends of the pair of contact portions <NUM> are spaced apart from each other, and the bus bar terminal <NUM> may be inserted into a space between the pair of contact portions <NUM>. A distance d1 between the ends of the pair of contact portions <NUM> spaced apart from each other may be less than a width of the bus bar terminal <NUM> and may be elastically deformed when the bus bar terminal <NUM> is inserted between the pair of contact portions <NUM>.

In one embodiment, the distance d1 between the pair of contact portions <NUM> increases in a first region A1 starting from a point where the power terminal <NUM> branches, decreases in a second region A2, and increases again in a third region A3. The pair of contact portions <NUM> are designed according to a stress analysis result to prevent cracks from occurring due to an expansion force applied when the pair of contact portions <NUM> are spread apart to be brought into contact with the bus bar terminal <NUM>. As the stress analysis result, damage caused by stress may be minimized by setting, to a curved region, a branch region X1 to which maximum stress is applied.

A section changed from the second region A2 to the third region A3 is in contact with the bus bar terminal <NUM>, and the third region A3 may include a curved portion to facilitate the insertion of the bus bar terminal <NUM>.

The bus bar body <NUM> may be provided with a plurality of first protrusions 141a to guide the position of the pair of contact portions <NUM>. The first protrusions 141a may be arranged in pairs and protrude upward from the bus bar body <NUM>.

The pairs of first protrusions 141a may be spaced apart from each other, and the bus bar terminal <NUM> may pass between the first protrusions 141a. The power terminal <NUM> may be inserted between the first protrusions 141a, and the bus bar terminal <NUM> passing between the first protrusions 141a may be inserted into the contact portions <NUM> to be in contact with the contact portions <NUM>.

The first protrusions 141a may not only guide the position of the bus bar terminal <NUM> but also prevent the separation or movement of the contact portions <NUM> in contact with the bus bar terminal <NUM> to maintain an electrically stable contact. A shape of the first protrusions 141a is not limited but may be changed in various shapes to support both sides of the contact portions <NUM>.

<FIG> illustrates the bus bar terminal <NUM> which is coupled to the power terminal in <FIG> according to an embodiment.

Referring to <FIG>, both sides of the bus bar terminal <NUM> in contact with the contact portions <NUM> may include a curved portion 143b. The curved portion 143b may be provided to match in shape to a contact side of the contact portion <NUM> in contact therewith in a curved form.

The curved portion 143b may facilitate the insertion of the contact portion <NUM> into the bus bar terminal <NUM> and maintain a stable coupling state by increasing a contact area through shape matching.

<FIG> is a diagram illustrating a structure in which the motor housing <NUM> and the connector unit <NUM> of <FIG> are connected to each other.

Referring to <FIG>, the connector unit <NUM> is disposed on the motor housing <NUM>. Various components, such as the power terminal <NUM>, a substrate, and a hall-integrated circuit (IC), are disposed on the connector unit <NUM> and a position thereof should be fixed when the power terminal <NUM> is combined with the motor unit <NUM>.

In order to fix the position of the connector unit <NUM>, the motor housing <NUM> may be provided with at least one hole 151a and the connector unit <NUM> may be provided with at least one second protrusion 231a. The positions of the hole 151a and the second protrusion 231a may respectively intersect those of the connector unit <NUM> and the motor housing <NUM>, and a description about the formation of the hole 151a in the connector unit <NUM> and the formation of the second protrusion 231a on the motor housing <NUM> will be omitted.

A protrusion <NUM> may be provided on a side of the motor housing <NUM>. The protrusion <NUM> may extend from an upper portion of the motor housing <NUM>, and the hole 151a may be formed in a region of a center of the protrusion <NUM>. A shape of the hole 151a is not limited but may have the same cross-sectional shape as the second protrusion 231a so that the second protrusion 231a of the connector unit <NUM> may be inserted into the hole 151a.

The connector connection part <NUM> may include a first connection portion <NUM> and a second connection portion <NUM>.

The first connection portion <NUM> is connected to a side of the connector body <NUM> and is disposed to face the protrusion <NUM> when the connector connection part <NUM> and the motor housing <NUM> are coupled to each other. In this case, the first connector portion <NUM> may be provided with the second protrusion 231a, and the second protrusion 231a may be inserted into the hole 151a to fix the position of the connector unit <NUM>.

In one embodiment, the second protrusion 231a may be provided in a cylindrical shape, the upper portion of which is inclined to be easily inserted into the hole 151a.

In addition, the first connector portion <NUM> may be provided with a rib 231b in a region at the center thereof, and the second protrusion 231a may be disposed on the rib 231b. The rib 231b may be arranged in a specific structure or may be formed by coring a basic structure. The rib 231b may be disposed in a lengthwise direction of the first connection portion <NUM> to resist bending or warping of the first connection portion <NUM>.

A plurality of grooves 231c may be provided at both sides of the second protrusion 231a of the first connection portion <NUM>. In one embodiment, the plurality of grooves 231c may be arranged at regular intervals and in a direction perpendicular to a direction of the rib 231b.

The second connection portion <NUM> may be connected to the first connection portion <NUM> to receive external power. In one embodiment, the second connection portion <NUM> may be connected at a certain angle to the first connection portion <NUM>. An angle at which the second connection portion <NUM> and the first connection portion <NUM> are connected to each other may be modified according to an angle at which the second connection portion <NUM> is installed to receive power.

<FIG> is a diagram illustrating a first suction port <NUM> and a first discharge port <NUM> formed in the first cover <NUM> of <FIG>. <FIG> is a diagram illustrating a second suction port <NUM> and a second discharge port <NUM> formed in the second cover <NUM> of <FIG>. <FIG> is a diagram illustrating a structure of the pump unit <NUM> of <FIG>. <FIG> is a diagram illustrating a state in which the pump unit <NUM> is positioned in the first cover <NUM>. <FIG> is a diagram illustrating the pump unit <NUM> is positioned in the second cover <NUM>.

Referring to <FIG>, the pump unit <NUM> is disposed between the first cover <NUM> and the second cover <NUM>.

The pump unit <NUM> is inserted into a space, to which a fluid is supplied, between the second cover <NUM> and the first cover <NUM> and pumps oil by receiving power from the motor unit <NUM>. The first cover <NUM> and the second cover <NUM> are combined together to form a space in which the pump unit <NUM> is located. The first cover <NUM> and the second cover <NUM> are described separately according to functional characteristics but may be connected integrally to each other.

One side of the first cover <NUM> may be in contact with the connector unit <NUM> and the other side thereof includes a first side <NUM> for accommodating the pump unit <NUM>.

The first side <NUM> includes the first suction port <NUM> and the first discharge port <NUM>. The first suction port <NUM> and the first discharge port <NUM> may each have a conventional port shape.

The second cover <NUM> includes a second side <NUM> on which the pump unit <NUM> is disposed, and the second side <NUM> includes the second suction port <NUM> and the second discharge port <NUM>. The second suction port <NUM> may include an inlet <NUM>, which communicates with the second suction port <NUM> and through which oil is introduced, and an outlet <NUM> which communicates with the second discharge port <NUM>.

The second suction port <NUM> and the second discharge port <NUM> may be formed in an arc shape and provided to be tapered from one side to the other side. In addition, the second suction port <NUM> and the second discharge port <NUM> may be arranged such that a wider portion of the second suction port <NUM> faces a wider portion of the second discharge port <NUM> and a narrower portion of the second suction port <NUM> faces a narrower portion of the second discharge port <NUM>.

The second discharge port <NUM> may have a conventional port shape.

The second suction port <NUM> includes a third protrusion <NUM> protruding inward. The third protrusion <NUM> protrudes toward a space forming the second suction port <NUM> from an end of the second suction port <NUM> farther from the center of the first rotor <NUM> among ends of the second suction port <NUM>.

The suction port and discharge port are formed respectively on the first cover <NUM> and the second cover <NUM> to guide a fluid to be smoothly suctioned and discharged by the pump unit <NUM>. These suction port and discharge ports are arranged by partitioning a space. This is to prevent movement of the fluid due to a pressure difference.

Referring to <FIG>, the pump unit <NUM> is disposed between the first cover <NUM> and the second cover <NUM> and pumps a fluid by receiving power from the motor unit <NUM>. The pump unit <NUM> includes the first rotor <NUM> and the second rotor <NUM>. The first rotor <NUM> may be referred to as an inner rotor <NUM> and the second rotor <NUM> may be referred to as an outer rotor <NUM>.

A turning force is directly applied to the first rotor <NUM> from the motor unit <NUM> because the shaft <NUM> is coupled to a central portion of the first rotor <NUM>. In one embodiment, the shaft <NUM> includes at least one cut surface <NUM> and may be inserted into a third coupling hole <NUM> formed in the center of the first rotor <NUM>. The third coupling hole <NUM> may match in shape with the shaft <NUM> to which the third coupling hole <NUM> is inserted, thereby preventing the first rotor <NUM> from running idle during rotation of the shaft <NUM>.

The second rotor <NUM> is disposed outside the first rotor <NUM>. In addition, in the first rotor <NUM>, a first lobe <NUM> with N gear teeth facing outward in a radial direction with respect to the center of rotation is provided in a circumferential direction. The second rotor <NUM> is provided with N+<NUM> second lobes <NUM> facing inward in the radial direction. The second lobe <NUM> is disposed to be caught by the first lobe <NUM>. As the first rotor <NUM> rotates, the second rotor <NUM> rotates in connection with the first rotor <NUM>.

Meanwhile, a diameter of a dedendum circle C1 of the first rotor <NUM> (hereinafter referred to as "D1") and a diameter of a dedendum circle C2 of the second rotor <NUM> (hereinafter referred to as "D2") are criteria for forming a space for pumping oil.

Oil may be stably supplied in high-speed regions by changing the shape of a suction port.

<FIG> illustrates a contact structure between the first suction port <NUM> and the first discharge port <NUM> which are formed on the first cover <NUM>, similarly to a structure of the related art.

However, when the first cover <NUM> and the second cover <NUM> are combined together, the first suction port <NUM> and the second suction port <NUM> face each other and the first discharge port <NUM> and the second discharge port <NUM> face each other. In this case, the first suction port <NUM> and the second suction port <NUM> are arranged in different shapes.

Referring to <FIG>, the first rotor <NUM> and the second rotor <NUM> are disposed such that the centers thereof do not coincide with each other. When a center P1 of the first rotor <NUM> and a center P2 of the second rotor <NUM> are projected onto the second cover <NUM>, an angle formed by a first line L1 connecting the center P1 of the first rotor <NUM> and the center P2 of the second rotor <NUM> and a second line L2 connecting the center P1 of the first rotor <NUM> and an end of the third protrusion <NUM> is inversely proportional to the number of gear teeth. A flow rate and velocity of a fluid to be introduced may be determined by an arrangement position of the third protrusion <NUM>.

An angle θ formed by the first line L1 and the second line L2 may be calculated by Equation <NUM> below.

Here, N represents the number of gear teeth formed on the first rotor <NUM>.

The position of the end of the third protrusion <NUM> may be determined according to the angle θ formed by the first line L1 and the second line L2.

In one embodiment, when the first rotor <NUM> includes five gear teeth as illustrated in <FIG>, θ may be set to <NUM> degrees.

In this case, θ may be changed within a range of <NUM>%.

A third line L3 connecting ends of the second suction port <NUM> in a region adjacent to the third protrusion <NUM> is parallel to the first line L1. Two recessed regions are formed at ends of the second suction port <NUM> due to the third protrusion <NUM> formed inside the second suction port <NUM>, and the third line L3 connects innermost sides of the two recessed regions.

In addition, the first line L1 and the third line L3 are parallel to each other, a distance d2 between the first line L1 and the third line L3 is proportional to a distance between the center P1 of the first rotor <NUM> and the center P2 of the second rotor <NUM>.

In one embodiment, the distance d2 between the first line L1 and the third line L3 may be calculated by Equation <NUM> below.

Here, e represents the distance between the center P1 of the first rotor <NUM> and the center P2 of the second rotor <NUM>.

Therefore, the arrangement position of the third protrusion <NUM> of the second suction port <NUM> may be determined by the number N of gear teeth of the first rotor <NUM> and a distance e between the center P1 of the first rotor <NUM> and the center P2 of the second rotor <NUM>.

<FIG> is a diagram showing a change in flow rate performance when the shape of the second cover of <FIG> is applied.

Referring to <FIG>, in the related art, an increase in flow rate decreased when the speed of rotation was <NUM> rpm or more and decreased greatly when the speed of rotation exceeded <NUM> rpm.

However, when the shape of the second cover <NUM> was applied, a constant flow rate increase was secured even when the speed of rotation exceeded <NUM> rpm and was continuously maintained even when the speed of rotation exceeded <NUM> rpm.

<FIG> is a longitudinal sectional view of a motor not part of the present invention. <FIG> is a cross sectional view taken along line A-A of <FIG>.

Referring to <FIG> and <FIG>, a motor <NUM> may include a housing <NUM>, a bracket <NUM>, a rotor <NUM>, a stator <NUM>, and a shaft <NUM>. Here, the bracket <NUM> may be disposed to cover an open upper portion of the housing <NUM>.

The housing <NUM> and the bracket <NUM> may form an exterior of the motor <NUM>. Here, the housing <NUM> may be formed in a cylindrical shape having an opening thereon.

Therefore, an accommodation space may be formed in the motor <NUM> due to coupling of the housing <NUM> and the bracket <NUM>. As illustrated in <FIG>, the rotor <NUM>, the stator <NUM>, the shaft <NUM>, and the like may be disposed in the accommodation space.

The housing <NUM> may be formed in a cylindrical shape so that the stator <NUM> may be supported on an inner circumferential surface of the housing <NUM>. A pocket portion for accommodation of a bearing <NUM> supporting a lower portion of the shaft <NUM> may be provided at the bottom of the housing <NUM>.

The bracket <NUM> disposed on the top of the housing <NUM> may also be provided with a pocket portion for supporting an upper portion of the shaft <NUM>. The bracket <NUM> may include a hole or a groove into which a connector, to which an external cable is connected, is inserted.

The rotor <NUM> is disposed inside the stator <NUM>. Here, an inner side with respect to a radial direction (a y-axis direction) refers to a direction toward a center CC with respect to the center CC, and an outer side refers to a direction opposite that of the inner side. The center CC is the center of rotation of the shaft <NUM> and may be a center CC of the rotor <NUM>.

The rotor <NUM> may include a rotor core <NUM> and a magnet <NUM>.

Here, the rotor <NUM> may be an interior permanent magnet (IPM) type rotor in which the magnet <NUM> is coupled to the inside of the rotor core <NUM>. Accordingly, the rotor <NUM> may include a pocket into which the magnet <NUM> is inserted.

<FIG> is a diagram illustrating a rotor core of a motor not part of the present invention.

Referring to <FIG>, a rotor core <NUM> may include a main body <NUM>, a pocket <NUM>, a first barrier <NUM>, a second barrier <NUM>, and a hole <NUM>.

The main body <NUM> forms an exterior of the rotor core <NUM>.

Here, the main body <NUM> may be formed by stacking a plurality of thin steel plates together.

A magnet <NUM> is disposed in the pocket <NUM>.

As illustrated in <FIG>, a plurality of pockets <NUM> may be formed to be spaced apart from each other in a circumferential direction with respect to a center CC of the rotor core <NUM>. Accordingly, magnets <NUM> may be disposed in the circumferential direction with respect to the center CC of the rotor core <NUM>. In this case, the magnets <NUM> may be inserted into the pockets <NUM>.

The first barrier <NUM> may extend from both sides of the pocket <NUM>. As illustrated in <FIG>, when the magnets <NUM> are disposed in the pockets <NUM>, the first barriers <NUM> may be disposed at both sides of the magnets <NUM>.

An air layer may be formed on the first barrier <NUM>. Accordingly, the first barrier <NUM> serves as a flux barrier to prevent a short circuit and a leakage of magnetic flux.

However, when only the first barrier <NUM> is disposed on the main body <NUM> without the second barrier <NUM>, the magnet <NUM> may not be fully magnetized when the magnet <NUM> is magnetized using only a certain amount of a current. Here, the magnetization refers to applying, to a magnet, an external magnetic field about <NUM> to <NUM> times a coercive force of the magnet. In this case, a high current is used to generate the external magnetic field. In particular, when the magnet is an NdFeB-based rare earth magnet, a peak value of a magnetizing field is determined by saturation magnetic flux density.

When a certain current is applied, the second barrier <NUM> adjusts magnetic flux saturation of the main body <NUM> so that a maximum H field may be present in the magnet <NUM>. Accordingly, the magnet <NUM> may be fully magnetized.

<FIG> is a diagram illustrating region B of <FIG>, and the region B is part of the rotor <NUM>.

Referring to <FIG> and <FIG>, a plurality of second barriers <NUM> may be arranged in the circumferential direction. For example, two second barriers <NUM> may be arranged adjacent to one magnet <NUM>. Here, the arrangement of the two second barriers <NUM> adjacent to one magnet <NUM> may be understood to mean that the second barriers <NUM> are arranged such that outer circumferential surfaces thereof are spaced a certain distance from the magnet <NUM>.

The second barriers <NUM> may be formed between an inner circumferential surface 311a and an outer circumferential surface 311b of the main body <NUM>. As illustrated in <FIG>, the second barriers <NUM> may be formed between the inner circumferential surface 311a of the main body <NUM> and an inner side <NUM> of the magnet <NUM>.

The second barrier <NUM> may be formed to have a circular cross section having a certain radius R. That is, a size of the second barrier <NUM> may be defined by the radius R. Here, an example in which the second barrier <NUM> has a circular cross section has been described. As illustrated in <FIG>, the second barrier <NUM> may be provided as a polygonal shape, such as a hemispherical shape, an ellipse shape, a tetragonal shape or a hexagonal shape, or a bent tetragonal shape in consideration of an arrangement position of the second barrier <NUM>.

The second barriers <NUM> may be disposed to be symmetric to each other with respect to a first line L11. As illustrated in <FIG>, two second barriers <NUM> disposed to correspond to one magnet <NUM> may be symmetric to each other with respect to the first line L11. Here, the first line L11 is a line passing through the center CC of the main body <NUM> and the center of a width W of the magnet.

The arrangement position of the second barrier <NUM> may be defined by an arrangement angle θ and an arrangement distance D33 from the center CC of the rotor core <NUM>.

A center C111 of the second barrier <NUM> may have a certain arrangement angle θ with respect to the first line L11 in the circumferential direction. For example, the arrangement angle θ may be an angle formed by the first line L11 and a second line L22 passing through the center CC of the main body <NUM> and the center C11 of the second barrier <NUM>. In this case, an included angle between the first line L11 and the second line L22 is an angle with respect to the center CC.

In this case, the inner side <NUM> of the magnet <NUM> may be disposed on the second line L22 passing through the center CC of the main body <NUM> and the center C11 of the second barrier <NUM>. As illustrated in <FIG>, one point P1 on the outer circumferential surface of the second barrier <NUM> and one point P2 on the inner side <NUM> of the magnet <NUM> may be disposed on the second line L22.

The arrangement angle θ may be calculated by Equation <NUM> below.

As illustrated in <FIG>, W represents a width of a magnet, D11 represents the distance from the center of a main body to an inner side surface of the magnet, and D22 represents the distance from the center of the main body to an outer side surface of the magnet.

For example, when the rotor <NUM>, which is an IPM type, is designed, the arrangement angle θ is less than <NUM> degrees and greater than <NUM> degrees when W is <NUM>, D11 is <NUM>, and D22 is <NUM>. Accordingly, the arrangement angle θ of the second barrier <NUM> may be designed to be an angle between <NUM> degrees and <NUM> degrees.

The arrangement distance D33 may be calculated by Equation <NUM> below. Here, the arrangement distance D33 is a distance from the center CC of the main body <NUM> to the center of the second barrier <NUM>.

As illustrated in <FIG>, O represents the distance between one point P1 on the outer circumferential surface of the second barrier <NUM> and one point P2 on the inner side <NUM> of the magnet <NUM>, which are located on the second line L22.

As described above, when the arrangement angle θ is set to <NUM> degrees to be within a range of the arrangement angle θ, R is set to <NUM>, and O is set to <NUM>, which are design parameters, the arrangement distance D33 is determined to be <NUM> according to Equation <NUM> above.

Therefore, the arrangement position of the second barrier <NUM> is determined by the placement angle θ of <NUM> degrees and the placement distance D33 of <NUM>.

When the arrangement angle θ is set to <NUM> degrees to be within the range of the arrangement angle θ and design parameters R and O are respectively set to <NUM> and <NUM>, the arrangement distance D33 is determined to be <NUM> according to Equation <NUM> above.

The second barrier <NUM> may be formed to be long from an upper end of the main body <NUM> to a lower end of the main body <NUM>. However, a length of the second barrier <NUM> in an axial direction (an x-axis direction) may be the same as a length of the magnet <NUM> in the axial direction (the x-axis direction). Here, an air layer may be formed on the second barrier <NUM>.

The hole <NUM> may be formed in a central portion of the body <NUM>. Accordingly, the shaft <NUM> may be coupled to the hole <NUM>.

The magnet <NUM> may be provided in the form of a tetragonal pillar extending from the upper end of the rotor core <NUM> to the lower end of the rotor core <NUM>. An example in which six magnets <NUM> are disposed in the motor <NUM> has been described above.

In this case, the magnitude of an external magnetic field required to magnetize the magnets <NUM> varies according to energy density, coercive force, saturation magnetic flux density, etc. of a material of the magnets <NUM>.

<FIG> is a diagram showing a comparison of an H field with respect to a rotor of a motor according to an example with an H field with respect to a rotor of a motor according to a comparative example. <FIG> is a diagram illustrating the H field of the motor according to the example, and <FIG> is a diagram illustrating the H field of the motor according to the comparative example. Here, a motor <NUM> provided as the comparative example is different from the motor <NUM> in terms of the presence of and an arrangement position of the second barrier <NUM>.

Referring to <FIG>, when a magnetization peak current of <NUM> kA is supplied to the motor <NUM> and the motor <NUM> of the comparative example, an H field of the magnet <NUM> of the motor <NUM> is <NUM>*<NUM>^<NUM> A/m and an H field of the motor <NUM> of the comparative example is <NUM>* <NUM>^<NUM> A/m. In this case, the radius R of the second barrier <NUM> is <NUM>.

That is, in the case of the motor <NUM>, a magnitude of the H field is increased by about <NUM>% due to the second barrier <NUM>. Accordingly, a magnetizing current of the motor <NUM> may be reduced from <NUM> kA to <NUM> kA. That is, the motor <NUM> of the comparative example to which <NUM> kA is applied and the motor <NUM> to which <NUM> kA is applied have the same magnetization performance.

Therefore, the lowest H field of the motor <NUM> with the second barrier <NUM> increases and thus magnetization power of the motor <NUM> is improved compared to the motor <NUM> of the comparative example. In addition, a local non-magnetized region of the magnet <NUM> decreases.

Meanwhile, the H field may be adjusted by the radius R of the second barrier <NUM>. That is, as the radius R of the second barrier <NUM> is adjusted, the arrangement distance D3 is adjusted and thus a magnetization performance difference occurs.

When the radius R of the second barrier <NUM> is adjusted to <NUM> and a magnetizing peak current of <NUM> kA is supplied to the motor <NUM> and the motor <NUM> of the comparative example, an H field of the magnet <NUM> of the motor <NUM> is <NUM>* <NUM>^<NUM> A/m and an H field of the motor <NUM> of the comparative example is <NUM>* <NUM>^<NUM> A/m.

That is, in the case of the motor <NUM>, the magnitude of the H field is improved by about <NUM>% due to the second barrier <NUM>.

Accordingly, the second barrier <NUM> of the motor <NUM> may increase the magnitude of a magnetization field in the magnet <NUM>, thereby increasing a magnetization feature of the magnet <NUM>. In addition, the arrangement distance D3 is adjusted by the radius R of the second barrier <NUM>.

<FIG> is a diagram showing a comparison of a uniform magnetic flux line of a rotor of a motor according to an example with a uniform magnetic flux line of a rotor of a motor according to a comparative example. <FIG> is a diagram illustrating the uniform magnetic flux line of the motor of the example, and <FIG> is a diagram illustrating the uniform magnetic flux line of the motor of the comparative example.

Referring to <FIG>, a second barrier <NUM> of a motor <NUM> causes a change in magnetic resistance to change a magnetic flux path. In particular, the second barrier <NUM> with an air layer has low permeability and thus a magnetic flux path in the rotor core <NUM> may be greatly changed. Accordingly, a magnetic flux is concentrated at an inner edge of the magnet <NUM> and thus the motor <NUM> has a higher magnetic flux density distribution than the motor <NUM> of the comparative example.

<FIG> is a diagram showing a comparison of magnetic flux density of a rotor of a motor according to an example with magnetic flux density of a rotor of a motor according to a comparative example. <FIG> is a diagram illustrating an H field of the motor of the example, and <FIG> is a diagram illustrating an H field of the motor of comparative example.

Referring to <FIG>, the lowest magnetic flux density of the motor <NUM> is higher than that of the motor <NUM> of the comparative example. Accordingly, a magnitude of an external magnetic field applied to an inner corner of the magnet <NUM> increases.

The stator <NUM> may be supported by the inner circumferential surface of the housing <NUM>. The stator <NUM> is disposed outside the rotor <NUM>. That is, the rotor <NUM> may be disposed on an inner side of the stator <NUM>.

Referring to <FIG> and <FIG>, the stator <NUM> may include a stator core <NUM> and a coil <NUM>. Here, the stator core <NUM> may be formed by stacking a plurality of thin steel plates together. Alternatively, the stator core <NUM> may be formed by coupling or connecting a plurality of split cores to each other.

The stator core <NUM> may include a yoke <NUM> and teeth <NUM>.

The yoke <NUM> may be formed in a cylindrical shape.

The teeth <NUM> may be disposed to protrude from the yoke <NUM> toward the center CC. As illustrated in <FIG>, the teeth <NUM> may be disposed at regular intervals along an inner circumferential surface of the yoke <NUM> to protrude toward the center CC. That is, the teeth <NUM> may be disposed along the inner circumferential surface of the yoke <NUM> to be spaced a certain distance from each other.

A coil <NUM> may be wound around the teeth <NUM>. In this case, an insulator <NUM> may be disposed on the tooth <NUM>. The insulator <NUM> insulates the teeth <NUM> and the coil <NUM> from each other.

A current may be applied to the coil <NUM>. Accordingly, electrical interaction with the magnet <NUM> of the rotor <NUM> may be caused to rotate the rotor <NUM>. When the rotor <NUM> rotates, the shaft <NUM> also rotates. In this case, the shaft <NUM> may be supported by the bearing <NUM>.

The shaft <NUM> may be coupled to the rotor <NUM>. When electromagnetic interaction occurs between the rotor <NUM> and the stator <NUM> through the supply of current, the rotor <NUM> rotates and the rotation shaft <NUM> rotates in association with the rotor <NUM>.

Meanwhile, the motor <NUM> may further include a sensing magnet assembly <NUM> to identify the position of the rotor <NUM>.

The sensing magnet assembly <NUM> may include a sensing magnet and a sensing plate. The sensing magnet and the sensing plate can be combined to have the same axis.

The sensing magnet may include a main magnet disposed in a circumferential direction to be adjacent to a hole forming an inner circumferential surface thereof, and a sub-magnet formed at an edge thereof. The main magnet may be arranged in the same manner as a drive magnet inserted into the rotor <NUM> of the motor <NUM>. The sub-magnet is subdivided to have a larger number of poles than the main magnet. Therefore, a rotation angle may be more subdivided and measured, and the motor <NUM> may be more smoothly driven.

The sensing plate may be formed of a disc type metal material. An upper side of the sensing plate may be coupled to the sensing magnet. In addition, the sensing plate may be coupled to the shaft <NUM>. Here, the sensing plate is provided with a hole through which the shaft <NUM> passes.

In addition, the motor <NUM> may further include a printed circuit board <NUM> on which a sensor is disposed to sense a magnetic force of the sensing magnet.

In this case, the sensor may be a Hall IC. The sensor senses a change of N and S poles of the main magnet or the sub-magnet to generate a sensing signal. In the case of a three-phase brushless motor, at least three sensing signals are required to obtain information about U-, V-, and W-phases and thus at least three sensors may be arranged.

The printed circuit board <NUM> may be coupled to a bottom surface of the bracket <NUM> and installed on the sensing magnet assembly <NUM> such that the sensor faces the sensing magnet.

Embodiments of the present invention have been described above in detail with reference to the accompanying drawings.

While the technical idea of the present invention has been described above with respect to examples thereof, it will be apparent to those of ordinary skill in the art that various modifications, changes and alternatives may be made without departing from the essential features of the invention. Therefore, the embodiments disclosed herein and the accompanying drawings are not intended to restrict the scope of the present invention and are only used for a better understanding of the present invention. The scope of the present invention is not limited by these embodiments and the accompanying drawings. The scope of protection of the present invention should be interpreted based on the following claims.

Claim 1:
An electric pump comprising:
a motor unit (<NUM>) including a shaft (<NUM>), a rotor (<NUM>) coupled to the shaft (<NUM>), and a stator (<NUM>) disposed outside the rotor (<NUM>);
a pump unit (<NUM>) including a first rotor (<NUM>) coupled to the motor unit (<NUM>) and including a first lobe (<NUM>) with a plurality of gear teeth and a second rotor (<NUM>) disposed outside the first rotor (<NUM>) and including a second lobe (<NUM>) disposed to be caught by the first lobe (<NUM>);
a first cover (<NUM>) disposed between the motor unit (<NUM>) and the pump unit (<NUM>) and including a first suction port (<NUM>) and a first discharge port (<NUM>) disposed on one side of the first cover (<NUM>); and
a second cover (<NUM>) disposed on a front side of the pump unit (<NUM>), combined with the first cover (<NUM>) to accommodate the pump unit (<NUM>) and including a second suction port (<NUM>) and a second discharge port (<NUM>) disposed on a second side (<NUM>) on which the pump unit (<NUM>) is disposed, characterized in that
the first suction port (<NUM>) and the second suction port (<NUM>) are different in shape,
wherein the second suction port (<NUM>) includes two recessed regions at ends of the second suction port (<NUM>) due to a third protrusion (<NUM>) formed inside the suction port (<NUM>),
wherein an angle formed by a first line connecting a center of the first rotor (<NUM>) and a center of the second rotor (<NUM>) and a second line (L2) connecting the center of the first rotor (<NUM>) and an end of the third protrusion (<NUM>) is inversely proportional to the number of the gear teeth of the first lobe (<NUM>), and
wherein the first line (L1) and a third line (L3) connecting the ends of the second suction port (<NUM>) in a region adjacent to the third protrusion (<NUM>) are parallel to each other, and
wherein a distance (d2) between the first line (L1) passing through a center (P1) of the first rotor (<NUM>) and a center (P2) of the second rotor (P2) and the third line (L3) connecting the center P1 of the first rotor (<NUM>) and an end of the third protrusion (<NUM>) is proportional to a distance (e) between the center (P1) of the first rotor (<NUM>) and the center (P2) of the second rotor (<NUM>).