Pump module and electric pump including the same

A pump module may include a pump rotor coupled to a rotating shaft of a motor, and a pump housing configured to accommodate the pump rotor. The pump housing includes a rotor accommodating part having an insertion groove formed therein to accommodate the pump rotor, and a cover connected with the rotor accommodating part and having a fluid sucking hole and a fluid discharging hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean Application No. 10-2013-0140729 filed on Nov. 19, 2013, whose entire disclosure is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a pump module and an electric pump including the same, and more particularly, to an electric oil pump.

An oil pump serves to discharge a flow rate of oil with a constant pressure. Oil circulated by the oil pump is used to operate a hydraulic system using an oil pressure, or to obtain a cooling or lubricant effect. A mechanical oil pump (MOP) is an oil pump operated using mechanical power such as an engine.

Recently, studies on hybrid vehicles and electric vehicles have been carried out to improve fuel efficiency and to reduce carbon emission. Therefore, demand for electric oil pumps (EPOs) is being increased, instead of the MOP using mechanical power.

The EOP has a pump-integrated structure in which a housing of a pump is integrally formed with a housing of motor. The pump-integrated structure has advantages including a reduced volume and a light weight. However, the pump may be damaged while the motor is assembled. Further, in a new development on the EOP, the motor should be redesigned even by a minor design change of the pump, so it is difficult to standardize the EOP, and it is not possible to separately assemble and test the pump before an assembling of the pump and the motor.

DETAILED DESCRIPTION

Referring toFIGS. 1 to 3, the EOP according to one embodiment of the present disclosure includes a motor module100and a pump module200. The motor module100includes a rotating shaft110, a rotor120, a stator130, a motor housing140, a first cover150, a sealing member160and a bearing170. The pump module200includes a pump rotor210and a pump housing220.FIG. 2illustrates an example in which the motor module100is an internal permanent magnet (IPM) type in which a rotor magnet122is inserted into a rotor core121. However, the embodiment of the present disclosure is not limited thereto. The motor module according to another embodiment of the present disclosure may be a surface permanent magnet (SPM) type in which the rotor magnet is attached to an outer circumferential surface of the rotor.

The rotating shaft110is integrally coupled to a center portion of the rotor120, and serves to transmit a rotating force according to rotation of the rotor120to the pump module200. The stator130is fixed to an inner circumferential surface of the motor housing140, and has a space formed therein to accommodate the rotor120. The stator130includes a stator core131and a coil132wound on the stator core131.

When a current is applied to the coil132of the stator130, the rotor120is rotated by an electromagnetic interaction between the stator130and the rotor120. Therefore, the rotating shaft110coupled to the rotor120is rotated along with the rotor120, and thus the rotating force may be transmitted to the pump module200.

The motor housing140is a cylindrical member of which an upper portion is opened, and the rotor120and the stator130are accommodated in an inner space thereof. The first cover150is airtightly coupled to the upper portion of the motor housing140in an air tight manner, or alternatively, hermetically sealed. For the sake of convenience of explanation, a motor module100side ofFIG. 2is defined as an “upper portion”, and a pump module200side thereof is defined as a “lower portion”.

A through-hole144through which the rotating shaft110passes is formed in a bottom surface of the motor housing140. The through-hole144serves to support one end of the rotating shaft110. Therefore, a separate bearing structure for supporting the one end of the rotating shaft110may be omitted. At this time, a fluid may be introduced into a gap between the through-hole144and the rotating shaft110and may perform a lubrication action.

A sealing member accommodating part141configured to accommodate the sealing member160is formed around the through-hole144. The sealing member160is coupled with the rotating shaft110to surround an outer surface of the rotating shaft110, and serves to prevent a fluid circulated in the pump module200from being introduced to the motor module100side. Since the sealing member160is disposed between the through-hole144and the rotor120, the fluid introduced into the gap between the through-hole144and the rotating shaft110is not introduced to the rotor side.

The sealing member160may include an oil seal or the like. The bearing170is coupled to the outer surface of the rotating shaft110so as to rotatably support the other end of the rotating shaft110.

The motor module100further includes a circuit board180and a second cover190which are coupled above the first cover150. The circuit board180includes a motor driving part such as an inverter and an inverter driving circuit, and serves to supply a current to the stator130and thus rotate the rotor120. The second cover190is coupled on the first cover150to seal the circuit board180.

The pump rotor210includes an internal rotor211coupled with one end of the rotating shaft110so as to receive the rotating force from the rotating shaft110, and an external rotor212configured to accommodate the internal rotor211. N lobes are formed on an outer circumferential surface of the internal rotor211, and N+1 lobes are formed in the external rotor212, and thus the internal rotor211is rotated at a rotation ratio of (N+1)/N.

The pump module200has a predetermined eccentric structure when the internal rotor211receives the rotating force from the rotating shaft110and is rotated. Due to the eccentric structure, a volume through which a fluid fuel is transported is generated between the internal rotor211and the external rotor212. That is, a portion in which the volume is increased, when the pump rotor210is rotated, sucks a peripheral fluid due to a pressure drop, and another portion in which the volume is reduced discharges the fluid due to a pressure increase.

The pump housing220includes a rotor accommodating part221formed therein to accommodate the pump rotor210, and a third cover222, and is coupled to one side of the motor housing140through a protrusion223. Referring toFIGS. 3 to 5, the rotor accommodating part221is formed in a cylindrical shape of which one side is opened, and has an insertion groove231formed therein to accommodate the pump rotor210. A depth of the insertion groove231may be the same as a thickness of the pump rotor210, but not limited thereto.

The third cover222is integrally formed with the rotor accommodating part221and forms a bottom surface236of the insertion groove231. An insertion hole232in which the rotating shaft110of the motor module100is inserted into a center portion thereof, and a main groove234configured to receive the fluid are formed in the bottom surface236of the insertion groove231. Further, a fluid sucking hole224(FIG. 1) and a fluid discharging hole225(FIG. 1) are formed in a thickness direction to pass therethrough.

In the rotor accommodating part221, a groove portion233in which an O-ring320is coupled is formed on one surface in contact with the motor housing140. The groove portion233may be a ring-shape groove surrounding the insertion groove231. The O-ring320is deformed when the pump housing220is coupled to one end of the motor housing140and a pressure is applied thereto, and fills up a gap between the two housings140and220.

A plurality of protrusions223protrude from an outer circumferential surface of the rotor accommodating part221. A through-hole235is formed at a center portion of each protrusion223, and a screw thread to be screwed with a fastening member310is formed on an inner circumferential surface of the through-hole235.

A coupling part142protrudes on one surface of the motor housing140to which the pump housing220is coupled. The coupling part142is formed of a ring shape of which a cross section corresponds to a cross section of the rotor accommodating part221. The coupling part142is mated with one surface of the rotor accommodating part221to seal the rotor accommodating part221.

A sub groove145in which the fluid is received may be formed in a bottom surface (facing the rotor accommodating part of the motor housing) of the coupling part142. The sub groove145may be designed to have a smaller depth than that of the main groove234.

A fastening groove143opposite to each through-hole235of the pump housing220is formed in the one surface of the motor housing140to which the pump housing220is coupled. A screw thread to be screwed with the fastening member310is formed on an inner circumferential surface of the fastening groove143.

Each through-hole235of the pump housing220and each fastening groove143of the motor housing140are arranged on one straight line when the motor housing140is coupled with the pump housing220. The fastening member310is sequentially fastened to the through-hole235and the fastening groove143so that the motor housing140is coupled with the pump housing220. The fastening member310may include a bolt having a screw thread formed on an outer circumferential surface thereof.

The EOP according to one embodiment of the present disclosure may be serves as an oil pump, and if necessary, may be properly modified into various fluid pumping structures such as a water pump.

Since the EOP having the above-mentioned structure may be designed to have the shortest distance of a fluid channel, a volume loss due to flow friction may be reduced, and a compact design may be allowed.

Further, a function of accommodating the pump rotor may be removed from the motor housing, and the pump rotor accommodating space may be integrated to the pump cover, and thus the motor housing may be simplified.

Further, the pump module and the motor module may be mechanically separated, and separately assembled and tested, and thus the motor may be standardized.

A pump module may include a pump rotor coupled to a rotating shaft of a motor, and a pump housing configured to accommodate the pump rotor, wherein the pump housing includes a rotor accommodating part having an insertion groove formed therein to accommodate the pump rotor, and a cover connected with the rotor accommodating part and having a fluid sucking hole and a fluid discharging hole. The pump rotor may include an internal rotor coupled to the rotating shaft, and an external rotor configured to accommodate the internal rotor.

The rotor accommodating part may include a protrusion in which a fastening member is fastened. The rotor accommodating part may include a first groove formed in a bottom surface of the insertion groove to receive a fluid. The rotor accommodating part may include a groove portion configured to surround the insertion groove, and an O-ring arranged in the groove portion. The rotor accommodating part may include an insertion hole formed at a center of a bottom surface of the insertion groove.

An electric pump may include a motor module including a rotating shaft, a rotor coupled to an outer circumferential surface of the rotating shaft, a stator configured to accommodate the rotor, and a motor housing configured to accommodate the rotor and the stator; and a pump module including a pump rotor coupled to one end of the rotating shaft, and a pump housing configured to accommodate the pump rotor, wherein the pump housing includes a rotor accommodating part having an insertion groove formed therein to accommodate the pump rotor; and a third cover connected with the rotor accommodating part and having a fluid sucking hole and a fluid discharging hole.

The rotor accommodating part may further include a protrusion configured to extend outwardly and having a through-hole, and the motor housing may include a fastening groove corresponding to the through-hole, and the electric pump may further include a fastening member sequentially fastened to the through-hole and the fastening groove.

The motor housing may include a through-hole configured to support one end of the rotating shaft. A fluid may be introduced into a gap between the through-hole and the rotating shaft.

The electric pump may include a sealing member disposed between the through-hole and the rotor. The electric pump may include a first cover configured to cover the motor module, a motor driving part coupled to the first cover, and a second cover configured to cover the motor driving part. The electric pump may include a bearing configured to support the other end of the rotating shaft.

The rotor accommodating part may include a first groove formed in a bottom surface of the insertion groove to receive a fluid. The motor housing may include a second groove formed at a surface thereof facing the rotor accommodating part to correspond to the first groove. A depth of the first groove may be larger than or the same as a depth of the second groove.

The rotor accommodating part may include a groove portion configured to surround the insertion groove, and an O-ring arranged in the groove portion. The rotor accommodating part may include an insertion hole formed at a center of a bottom surface of the insertion groove to support one end of the rotating shaft. The rotor accommodating part may be integrally formed with the third cover.

The pump rotor may include an internal rotor coupled to one end of the rotating shaft, and an external rotor configured to accommodate the internal rotor.

The terms including an ordinal number such as first, second, etc. can be used to describe various construction elements, but the construction elements should not be limited by those terms. The terms are used merely for the purpose to distinguish an element from another element. For example, a first element may refer to a second element, and similarly, a second element may refer to a first element without departing from the scope of the claims of the invention. The term “and/or” encompasses a combination of plural items or any one of the plural items.

It is to be noted that, in this specification, the expression that “a certain construction element is connected to another construction element” means that the certain construction element is directly connected to another construction element, and also means that a third construction element may be interposed therebetween. On the other hand, the expression that “the certain construction element is directly connected to another construction element” means that the third construction element is not interposed therebetween.

The terms used herein are merely to describe a specific embodiment, and thus the present disclosure is not limited thereto. Further, unless a singular expression clearly denotes a different meaning in context, it also includes a plural expression. It is understood that terms “comprises”, “comprising”, “includes” or “has” intend to indicate the existence of features, numerals, steps, operations, elements and components described in the specification or the existence of a combination of thereof, and do not exclude the existence of one or more other features, numerals, steps, operations, elements and components or the existence of the combination of thereof or additional possibility beforehand.