Electric oil pump for a hydraulic control and oil supply system provided with the same

Abstract

Electric hydraulic pump for a transmission, comprising: an electric motor (M) having a motor cover (13), a motor housing (11) coupled to the motor cover (13), and a stator (ST) and a rotor (RT) arranged within the motor cover (13) and the motor housing (11), a pump (PP) comprising a pump housing (15) forming a pump chamber (17) and a toothed rotor (19) arranged within the pump chamber (17), the pump (PP) being connected to the rotor (RT) via a motor shaft (MS) and being configured to receive rotational power from the electric motor (M), and a filter (23) arranged between the motor cover (13) and the pump housing (15) corresponding to a connection opening (CH) of the motor cover (13), wherein a plurality of oil circulation holes (OH) are formed in the motor cover (13), and the communication hole (CH) is formed in the motor cover (13) corresponding to the pump housing (15), and wherein an oil flow channel (21) is formed within the pump housing (15) and is configured to connect the communication port (CH) and an oil inlet (1) of the pump chamber (17).

Description

The present invention relates to an electric hydraulic pump for hydraulic pressure control of a transmission and an oil supply system thereof.Recently, increasing oil prices worldwide and the exacerbated exhaust emission regulations have forced vehicle manufacturers to make more efforts to develop technologies that can improve fuel consumption in an environmentally friendly manner.In particular, improvement in fuel consumption in a transmission can be achieved by improving power output efficiency, and improvement in power output efficiency can be achieved by minimizing unnecessary power consumption by a hydraulic pump.Recently, since a starter clutch has been used in a dual clutch transmission (DCT) or an automatic transmission (AT) in place of a torque converter, an electric hydraulic pump capable of reducing power loss by adjusting the rotational speed (U / min) of the pump to the required flow rate is used in place of a mechanical hydraulic pump.In other words, by using an electric hydraulic pump, supply of control oil (control oil for friction elements such as clutches and brakes selectively operated at the time of shifting) and lubricating oil (cooling, lubrication) is efficiently managed.FIG. 1 is a schematic hydraulic circuit diagram of a transmission using a typical motor-driven hydraulic pump.Referring to FIG. 1, an electric hydraulic pump OP includes an electric motor M and a pump PP. When the pump PP is driven by the electric motor M, oil is sucked into an oil inlet 1 of the hydraulic pump OP and discharged through an oil outlet 3 to form a line pressure in a line pressure hydraulic line L.An accumulator A is disposed in the line pressure hydraulic line L to store the hydraulic pressure while controlling the hydraulic pressure surge. A plurality of solenoid valves SOL control the line pressure and operate the friction elements such as a clutch C or a brake BK.It has been found that in the case of a dual clutch transmission (DCT) or an automatic transmission (AT) in which an electric hydraulic pump (OP) is used, control oil and lubricating oil are separated by a partition wall 7 in a transmission case 5 and are operated in consideration of hydraulic pressure efficiency, respectively. As a result, there is a disadvantage in the case of control oil that the rise of the oil temperature is slow. When the temperature increase speed of the control oil is slow, there is a problem that the state in which the oil viscosity is high continues for a long time.Although there is a method of increasing the temperature of the control oil by using a heat exchanger H of a separate heater, it has been found that this method has limitations in increasing the overall temperature of the control oil.CN 109 113 946 A describes an electric hydraulic pump for a transmission, including an electric motor including a motor cover, a motor housing coupled to the motor cover, and a stator and a rotor disposed inside the motor cover and the motor housing, and a pump including a pump housing forming a pump chamber and a tooth rotor disposed inside the pump chamber, the pump being connected to the rotor via a motor shaft and configured to receive a rotational power from the electric motor, wherein a plurality of oil circulation holes are formed in the motor cover, and a communication hole is formed in the motor cover corresponding to the pump housing, and wherein an oil flow channel is formed inside the pump housing and configured to communicate the communication hole and an oil inlet of the pump chamber with each other.Further electric hydraulic pumps for a transmission are known from U.S. Pat. No. 2017 / 0 016 442 A1, U.S. Pat. No. 2012 / 0 128 513 A1 and U.S. Pat. No. 5,181,837 A.The invention provides an electric hydraulic pump for hydraulic pressure control of a transmission and an oil supply system including the same for supplying oil to the pump while the oil circulating in the electric motor is heated by the heat of the electric motor acting as an oil heater.This is achieved according to the invention by an electric hydraulic pump for a transmission according to the features of claim 1 or 4 and an oil supply system for a transmission according to the features of claim 7. Advantageous refinements are described in the dependent claims.An electric hydraulic pump for a transmission according to an exemplary embodiment of the invention includes an electric motor including a motor cover, a motor housing coupled to the motor cover, and a stator and a rotor disposed inside the motor cover and the motor housing, and a pump including a pump housing forming a pump chamber and a tooth rotor (or a gear rotor) disposed inside the pump chamber. The pump is connected to the rotor via a motor shaft and receives a rotational power from the electric motor, a plurality of oil circulation holes are formed in the motor cover, and a connection hole is formed in the motor cover corresponding to the pump housing. An oil flow passage is formed inside the pump housing for connecting the communication port and an oil inlet of the pump chamber (to each other).The electric hydraulic pump further includes a filter disposed between the motor cover and the pump housing corresponding to the communication opening of the motor cover.The filter may be mounted on a stepped portion (or a stepped portion) formed in the oil flow passage inside the pump housing.The filter may include a circular guide and a mesh (or mesh) mounted within the circular guide.An electric hydraulic pump for a transmission according to another exemplary embodiment of the invention includes an electric motor including a motor cover, a motor housing coupled to the motor cover, and a stator and a rotor disposed inside the motor cover and the motor housing, and a pump including a pump housing forming a pump chamber and a tooth rotor (or a gear rotor) disposed inside the pump chamber, the pump being connected to the rotor via a motor shaft and receiving a rotational power from the electric motor, wherein a plurality of oil circulation holes are formed in the motor cover, and a connection hole is formed in the motor cover corresponding to the pump housing, and wherein an oil flow channel is formed inside the pump housing. The oil circulating through the plurality of oil circulation holes flows into the motor housing and is heated by the heat of the electric motor and guided to the pump chamber through the communication hole and the oil flow channel.An oil supply system for a transmission according to an exemplary embodiment of the invention includes a motor housing, a motor cover coupled to the motor housing and having a connection hole and a plurality of oil circulation holes through which oil is supplied, a stator and a rotor mounted in the motor housing and the motor cover, a pump housing connected to the motor cover, an oil flow passage connected to the connection hole is formed in the pump housing, and the pump housing forms a pump chamber having an oil inlet that receives the oil from the oil flow passage and an oil outlet that discharges the oil, a tooth rotor (or a gear rotor) mounted inside the pump housing and rotated by the rotor connected to the tooth rotor, and a plurality of solenoid valves that receive the oil from the oil outlet.The oil supply system further includes a filter disposed between the motor cover and the pump housing corresponding to the connection opening of the motor cover.In an exemplary embodiment of the invention, since a plurality of oil circulation holes are formed in an outer periphery of a motor cover, a communication hole is formed in a side of the motor cover corresponding to a pump housing, and an oil flow passage is formed inside the pump housing, the oil circulated in the motor housing is directly heated by the heat of the stator and the rotor and directly supplied to the pump via the oil inlet.Therefore, even if the temperature of the entire oil in the transmission case does not increase, the oil circulating in the engine case is heated by the electric motor and flows into the oil inlet, so that even in a low temperature environment unfavorable for the control of a clutch and a brake, the temperature of the transmission oil can be quickly increased to solve the problems such as deteriorated responsiveness and shift shock.In addition, the stator of the electric motor is cooled by the oil circulating in the motor housing, and the function of the oil warmer on the oil flowing into the pump can be performed, so that the use of the existing heat exchanger can be excluded and the energy efficiency can be increased.The invention will be explained in more detail with reference to the drawings. In the drawing, the following are shown: FIG. 1 is a schematic hydraulic circuit diagram of a transmission using a typical motor-driven hydraulic pump; FIG. 2 is a view of an electric hydraulic pump for a transmission according to an exemplary embodiment of the invention; FIG. 3 is a cross-sectional view of an electric hydraulic pump for a transmission according to an exemplary embodiment of the present invention; FIG. 4 is a perspective view of a filter used in an electric hydraulic pump for a transmission according to an exemplary embodiment of the invention; FIG. 5 is a sectional view taken along line V--V in FIG. 2; and FIG. 6 is a schematic hydraulic circuit diagram of a transmission using an electric hydraulic pump according to an exemplary embodiment of the invention.It is understood that throughout the drawings, corresponding reference numerals designate like or corresponding parts and features.As those skilled in the art would realize, the described embodiments may be modified in various other ways without departing from the spirit or scope of the invention.The drawings and descriptions are to be regarded as illustrative in nature and not as restrictive. Throughout the specification, the same reference numerals refer to the same or similar elements.FIG. 2 is a view of an electric hydraulic pump for a transmission according to an exemplary embodiment of the invention, and FIG. 3 is a cross-sectional view of an electric hydraulic pump for a transmission according to an exemplary embodiment of the invention.FIG. 4 is a perspective view of a filter used in an electric hydraulic pump for a transmission according to an exemplary embodiment of the invention, and FIG. 5 is a sectional view taken along line V-V in FIG. 2.Referring to FIGS. 2 to 5, an electric hydraulic pump OP for a transmission according to an exemplary embodiment of the invention includes an electric motor M and a pump PP.The electric motor M includes a motor housing 11 and a motor cover 13 coupled to the motor housing 11, and a stator ST and a rotor RT disposed in the motor cover 13 and the motor housing 11. The pump PP includes a pump housing 15 in which a pump chamber 17 is formed, and a tooth rotor 19 that is disposed in the pump chamber 17, is connected to the rotor RT via a motor shaft MS, and receives a rotational power from the electric motor M. The pump PP may be an external gear pump having two gears 19 and 19a externally toothed with each other and mounted in the pump chamber 17.That is, the first gear 19 is connected to the motor shaft MS, and the second gear 19 ais in external mesh with the first gear 19, and the pump PP discharges the oil corresponding to rotation of the electric motor M from an oil inlet 1 via an oil outlet 3.The pump used in the electric oil pump according to the exemplary embodiment of the invention is not limited to the external gear pump shown in FIG. 5. That is, various types of pumps such as an internal gear pump and a vane pump may be used.A plurality of oil circulation holes OH are formed in the motor cover 13, and a communication hole CH is formed in the motor cover 13 corresponding to the pump housing 15.The oil contained in the oil reservoir flows into the electric motor M via the oil circulation port OH so as to cool the stator ST and the rotor RT, and is supplied to the pump PP via the communication port CH while the temperature is increased.The pump housing 15 has an oil flow passage 21 formed therein to communicate the communication port CH with the oil inlet 1 of the pump chamber 17.In the communication hole CH of the motor cover 13, a filter 23 is installed between the motor cover 13 and the pump housing 15 to prevent the material contained in the oil from flowing into the pump chamber 17.Referring to FIG. 4, the filter 23 includes a circular guide 23 aand a mesh 23 bmade of steel coupled to the inside of the circular guide 23 a, and the circular guide 23 ais installed in a stepped portion 25 formed in the oil flow passage 21 inside the pump housing 15.The filter 23 is inserted into the stepped portion 25 by means of the circular guide 23a, and the pump housing 15 and the motor cover 13 are mounted and fixed.FIG. 6 is a schematic hydraulic circuit diagram of a transmission using an electric hydraulic pump according to an exemplary embodiment of the invention.Referring to FIG. 6, in a hydraulic circuit, the electric hydraulic pump OP according to an exemplary embodiment of the invention is immersed in the oil, and the oil is supplied to the motor housing 11 via the plurality of oil circulation holes OH formed in the motor cover 13 and heated by the heat of the electric motor M while circulating.That is, the oil is heated by absorbing heat while cooling the stator ST, which is the heat source of the electric motor M.Therefore, the heated oil is guided to the pump chamber 17 via the oil inlet 1 along the communication hole CH formed at one side of the motor cover 13 and the oil flow passage 21 formed in the pump housing 15.Here, regarding the heating of the oil, for example, a temperature sensor may be installed on the surface of the motor housing 11, and about 4 degrees per minute is achieved when the electric motor is driven. Based on this temperature, an increase of more than 4 degrees per minute (about 0.1 liter) can be expected.In the electric hydraulic pump OP for a transmission according to an exemplary embodiment of the invention, the oil flows into the motor housing 11 via the plurality of oil circulation holes OH in the motor cover 13 mounted in the motor housing 11, and the stator ST, which is the heat source of the electric motor M, is directly cooled.The heated oil absorbed by the electric motor M is directly guided to the pump chamber 17 of the pump PP via the communication hole CH formed in the motor cover 13, the oil flow passage 21 in the pump housing 15, and the oil inlet 1.Then, the oil having the elevated temperature is supplied to a plurality of solenoid valves SOL via the oil outlet 3 and a line pressure hydraulic line L.The solenoid valve SOL controls the operation of the clutch C or the brake BK by means of the heated oil, so that the control responsiveness can be improved.Although a partition wall 7 is formed in the transmission case 5 to separate the lubricating oil and the control oil from each other, the existing heat exchanger H and the like can be excluded.That is, even if the temperature of all the oil in the transmission case 5 does not rise, the oil circulating in the motor case 11 is guided to the pump PP while being directly heated by the heat source of the electric motor M, and thus the operation of the clutch C or the brake BK can be controlled. Therefore, even in low temperature environments, the temperature of the transmission oil can be rapidly increased to maintain the responsiveness and prevent shift shocks of the clutch C and the brake BK.In addition, the hydraulic pump OP according to an exemplary embodiment of the invention may exclude the use of the existing heat exchanger H through the function of the oil heater, thereby further increasing the energy efficiency.List of reference characters1 Oil inlet 3 Oil outlet 5 Transmission case 7 Partition wall OP Hydraulic pump M Electric motor PP Pump A Accumulator L Line pressure hydraulic line H Heat exchanger C Clutch BK Brake 11 Motor case 13 Motor cover 15 Pump case OH Oil circulation port CH Communication port 17 Pump chamber 19 Tooth rotor 21 Oil flow passage 23 Filter 23 aCircular guide 23 b Mesh 25 Stepped portion ST Stator RT Rotor MS Motor shaft

Claims

An electric hydraulic pump for a transmission, comprising: an electric motor (M) including a motor cover (13), a motor housing (11) coupled to the motor cover (13), and a stator (ST) and a rotor (RT) disposed inside the motor cover (13) and the motor housing (11); a pump (PP) including a pump housing (15) forming a pump chamber (17) and a tooth rotor (19) disposed inside the pump chamber (17), the pump (PP) being connected to the rotor (RT) via a motor shaft (MS) and configured to receive a rotational power from the electric motor (M); and a filter (23), An oil flow passage (21) is formed inside the pump housing (15) and is configured to connect the connection opening (CH) and an oil inlet (1) of the pump chamber (17) to each other between the motor cover (13) and the pump housing (15) corresponding to a connection opening (CH) of the motor cover (13), wherein a plurality of oil circulation openings (OH) are formed in the motor cover (13) and the connection opening (CH) is formed in the pump housing (15).The electric hydraulic pump according to claim 1, wherein the filter (23) is mounted on a stepped portion (25) formed in the oil flow passage (21) inside the pump housing (15).The electric hydraulic pump according to claim 1 or 2, wherein the filter (23) comprises: a circular guide (23a); and a braid (23b) mounted inside the circular guide (23a).An electric hydraulic pump for a transmission, comprising: an electric motor (M) including a motor cover (13), a motor housing (11) coupled to the motor cover (13), and a stator (ST) and a rotor (RT) disposed inside the motor cover (13) and the motor housing (11); a pump (PP) including a pump housing (15) forming a pump chamber (17) and a tooth rotor (19) disposed inside the pump chamber (17), the pump (PP) being connected to the rotor (RT) via a motor shaft (MS) and configured to receive a rotational power from the electric motor (M); and a filter (23), A pump chamber (17) is provided between the motor cover (13) and the pump housing (15) in correspondence with a communication hole (CH) of the motor cover (13), a plurality of oil circulation holes (OH) are formed in the motor cover (13), and the communication hole (CH) is formed in the motor cover (13) in correspondence with the pump housing (15), an oil flow passage (21) is formed inside the pump housing (15), and oil that circulates through the plurality of oil circulation holes (OH) and flows into the motor housing (11) is heated by heat of the electric motor (M) and is supplied to the pump chamber (17) through the communication hole (CH) and the oil flow passage (21).The electric hydraulic pump according to claim 4, wherein the filter (23) is mounted on a stepped portion (25) formed in the oil flow passage (21) inside the pump housing (15).The electric hydraulic pump according to claim 4 or 5, wherein the filter (23) comprises: a circular guide (23a); and a braid (23b) mounted inside the circular guide (23a).An oil supply system for a transmission, comprising: a motor housing (11); a motor cover (13) coupled to the motor housing (11) and having a connection hole (CH) and a plurality of oil circulation holes (OH) through which oil is supplied; a stator (ST) and a rotor (RT) mounted in the motor housing (11) and the motor cover (13); a pump housing (15) connected to the motor cover (13); wherein an oil flow channel (21) connected to the connection hole (CH) is formed in the pump housing (15); and the pump housing (15) forms a pump chamber (17) having an oil inlet (1) configured to receive the oil from the oil flow channel (21) and an oil outlet (3), which is configured to discharge the oil, a tooth rotor (19) mounted inside the pump casing (15) and rotated by the rotor (RT) connected to the tooth rotor (19), a plurality of solenoid valves (SOL) receiving the oil from the oil outlet (3), and a filter (23) disposed between the motor cover (13) and the pump casing (15) corresponding to the connection opening (CH) of the motor cover (13).

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