Electric water pump

Abstract

An electric water pump (10) comprising a pump body (22), a pressurization chamber (15) defined inside the pump body (22), an intake duct connected to the pressurization chamber (15), a delivery duct (14) connected to the pressurization chamber (15) and a pump electric motor (20) configured to drive the pump (10). The pump electric motor (20) comprises a casing (21), a stator (22) arranged inside the stator (22) coaxially to an axis (A) of the pump (10) and a rotor (24) arranged inside the stator (22) coaxially to the axis (A) of the pump (10). A cooling chamber (25) is defined between the pump body (22) and the casing (21). The electric water pump (10) also comprises an inlet duct (28) connected, at the opposite ends thereof (28a, 28b), respectively to the cooling chamber (25) and to the delivery duct (14), or to the pressurization chamber (15) at or close to the delivery duct (14), and an outlet duct (30) comprising a first duct portion connected to the cooling chamber (25) and a second duct portion connected to the intake duct, wherein the first duct portion is substantially parallel to the axis (A) and the second duct portion is substantially orthogonal to the axis (A).

Description

[0001] Electric water pump

[0002] DESCRIPTION

[0003] The present invention relates to an electric water pump.

[0004] Preferably, the electric water pump of the invention is used in the automotive sector, in particular in a cooling circuit of a main engine, for example an internal combustion engine, an electric engine or a hybrid engine, or of a fuel cell, or more generally of a Power Unit.

[0005] The invention also relates to a cooling circuit of a main engine or of a fuel cell or of a Power Unit comprising the aforesaid electric water pump.

[0006] In this description, reference will be made, in particular, to a main engine, more in particular to an internal combustion engine (petrol or diesel) of a motor vehicle, it being understood, however, that the description more generally applies also to main engines of different type and to other types of vehicles, as well as to the fuel cells and to the Power Units.

[0007] The electric water pump of the invention can also be used in sectors other than the automotive sector, in general where it is usual to use pressurized water.

[0008] Although throughout this description and in the following claims explicit reference will be made to water, the description also applies in the case where use is made of a liquid other than water, or a mixture of water and other liquids, or oil, or lubricating fluids, or more generally a heat transfer fluid.

[0009] Typically, in order to ensure the correct operation of a main engine of a motor vehicle, it is necessary to provide a special cooling circuit adapted to prevent overheating of the main engine.

[0010] Typically a cooling circuit comprises an electric water pump driven by an electric motor (hereinafter referred to as "pump electric motor" to distinguish this motor from the main engine to which the pressurized water exiting from the electric water pump is fed). This pump is in fluid communication with special cooling ducts that generally comprise cavities made in the casing of the main engine. The engine is cooled by convection heat exchange between the casing of the main engine and the cooling water circulating in the aforesaid cooling ducts.

[0011] The electric water pump can also be used to cool other utilities arranged in parallel or in series with the main engine. In particular, in the specific case of a petrol or diesel internal combustion engine, the water pushed by the electric water pump can also be sent to a heat exchanger to condition the oil of the lubrication circuit of the main internal combustion engine, while in the specific case of a diesel internal combustion engine, the water pushed by the electric water pump can also be sent to a further heat exchanger for cooling the valve for the recirculation of the exhaust gases of the main engine.

[0012] In specific operating conditions (for example at high values of the ambient temperature, and / or of the power delivered by the pump, and / or of the supply current level of the pump electric motor, etc.) it is advisable to provide for a cooling of the pump electric motor.

[0013] For this purpose it is known to make a cooling chamber in the pump stator in which a cooling liquid coming from a circuit external to the pump is circulated. This cooling liquid is fed into the cooling chamber through an inlet duct specifically provided in the pump and evacuated from the cooling chamber through an outlet duct specifically provided in the pump.

[0014] The Applicant has observed that this solution has the drawback of requiring both the provision of a circuit external to the pump for the circulation of the cooling liquid and the connection of the pump to said external circuit.

[0015] The technical problem underlying the present invention is to overcome the aforesaid drawback.

[0016] The Applicant has realised that this problem can be solved by using, for cooling the pump electric motor, a part of the water that is pressurized by the pump itself.

[0017] The present invention therefore relates, in a first aspect thereof, to an electric water pump in accordance with claim 1.

[0018] The electric water pump of the invention comprises a pump body, a pressurization chamber defined inside the pump body, an intake duct connected to the pressurization chamber, a delivery duct connected to the pressurization chamber, and a pump electric motor configured to control the pump.

[0019] The pump electric motor comprises a casing, a stator arranged inside the casing coaxially to an axis of the pump and a rotor arranged inside the stator coaxially to the axis of the pump.

[0020] Alternatively, the rotor can be arranged outside the stator and in any case always inside the casing coaxially to the axis of the pump.

[0021] The electric water pump further comprises a cooling chamber.

[0022] This cooling chamber can be made in the stator, or in the casing of the pump electric motor, or in the pump body, or be defined between the pump body and the casing of the pump electric motor.

[0023] The electric water pump of the invention also comprises an inlet duct connected, at the opposite ends thereof, to the cooling chamber and to the delivery duct, respectively, or to the cooling chamber and to the pressurization chamber at or close to the delivery duct, respectively, and an outlet duct comprising a first duct portion connected to the cooling chamber and a second duct portion connected to the intake duct, or to the pressurization chamber at or close to the intake duct, wherein the first duct portion is substantially parallel to the axis of the pump and the second duct portion is substantially orthogonal to the axis of the pump.

[0024] A part of the water that is pressurized in the pressurization chamber is circulated in the cooling chamber. This part of water is taken from the pressurization chamber or from the pump delivery duct and introduced into the cooling chamber through the inlet duct, to be then discharged from the cooling chamber and introduced into the pressurization chamber or into the intake duct through the outlet duct, thus creating a closed circuit inside the pump.

[0025] The relative positioning of the inlet duct and of the outlet duct is such that between the inlet and the outlet of the cooling chamber a pressure difference is created that is suitable to allow the circulation in the cooling chamber of the quantity of water necessary to ensure the cooling of the pump electric motor.

[0026] In a second aspect thereof, the invention relates to a cooling circuit of a main engine or of a fuel cell or of a Power Unit, comprising the aforesaid electric water pump.

[0027] Preferred features of the electric water pump and of the cooling circuit according to the invention are recited in the dependent claims. Unless expressly excluded, the features of each dependent claim may be used individually or in combination with those recited in the other dependent claims.

[0028] Preferably, the delivery duct, or at least a portion thereof, is substantially orthogonal to the axis of the pump. Preferably, the inlet duct, or at least a portion thereof, is substantially parallel to the axis of the pump.

[0029] Preferably, the intake duct is arranged on the opposite side with respect to the pump electric motor.

[0030] In some embodiments, the pressurization chamber and the cooling chamber are arranged between the intake duct and the pump electric motor.

[0031] Preferably, at least a portion of the intake duct extends coaxially to the axis of the pump.

[0032] According to the invention, the outlet duct comprises a first duct portion substantially parallel to the axis of the pump and a second duct portion substantially orthogonal to the axis of the pump.

[0033] Preferably, the first duct portion and the second duct portion of the outlet duct are substantially straight.

[0034] Preferably, the second duct portion of the outlet duct is connected to the intake duct.

[0035] Preferably, the second duct portion of the outlet duct is substantially orthogonal to the intake duct, or to at least a portion of the intake duct.

[0036] Preferably, the first duct portion of the outlet duct is angularly offset with respect to the inlet duct by an angle of less than 90°, said angle being measured at the axis of the pump.

[0037] Preferably, the cooling chamber has a substantially cylindrical shape.

[0038] Preferably, the cooling chamber extends around the axis of the pump over an angle greater than 270°. This ensures an effective cooling of the pump electric motor.

[0039] Preferably, the electric water pump comprises a compartment in which an electronic control unit is housed. Preferably, the cooling chamber is adjacent to said compartment. In this way, the electronic control unit benefits from the cooling induced by the water circulating in the cooling chamber.

[0040] Preferably, said compartment is arranged at an end portion of the electric water pump, or alongside the casing of the pump electric motor.

[0041] More preferably, the cooling chamber is arranged between the aforesaid compartment and the pressurization chamber.

[0042] Preferably, the pump electric motor is of the magnetic reluctance type, i.e. without permanent magnets.

[0043] Further characteristics and advantages of the present invention will become clearer from the following detailed description of a preferred embodiment thereof, made with reference to the appended drawings and given by way of indicative and non-limiting example. In such drawings: figure 1 is a perspective view of an electric water pump according to the present invention; figure 2 is a broken perspective view of the electric water pump of figure 1, in which some components have been removed; figure 3 is an axial sectional view of a part of the electric water pump of figure 1, the section being taken at the inlet duct described in the following of this description; figure 4 is an axial sectional view of a further part of the electric water pump of figure 1, the section being taken at the outlet duct described in the following of this description; figure 5 is a cross-sectional view of the electric water pump of figure 1, the section being taken at the trace plane V indicated in figure 3. An electric water pump in accordance with the present invention is shown in the attached figures. This pump is indicated with 10.

[0044] The pump 10 is suitable for being used in a cooling circuit (not shown) of a main engine (not shown), for example an internal combustion engine, an electric engine, a hybrid engine, a fuel cell or more generally a Power Unit.

[0045] As shown in figure 1, the pump 10 comprises an intake duct 12 configured to allow water to enter in the pump 10 and a delivery duct 14 configured to allow pressurized water to exit from the pump 10.

[0046] The intake duct 12 is coaxial to an axis A of the pump 10 while the delivery duct 14 is arranged in a radially external position with respect to the intake duct 12 and is substantially orthogonal to the intake duct 12 and therefore to the axis A.

[0047] In the specific example illustrated herein, the pump 10 is a centrifugal pump.

[0048] As shown in figure 2, the pump 10 comprises a pump body 22 inside which a spiral-shaped pressurization chamber 15 is defined. The pressurization chamber 15 is connected to the intake duct 12 and to the delivery duct 14.

[0049] An impeller 18 is arranged in the pressurization chamber 15.

[0050] The impeller 18 is coaxial to the axis A and is provided with a plurality of vanes 18a adapted to move the water inside the pressurization chamber 15 by putting it under pressure as a result of the generation of a centrifugal force. For clarity of illustration, reference numeral 18a is associated with only one of the illustrated vanes.

[0051] The impeller 18 is moved in rotation around the axis A by a pump electric motor 20 (figure 5) arranged close to the pressurization chamber 15. In particular, the pump electric motor 20 is adjacent to the pressurization chamber 15 and is arranged on the axially opposite side with respect to the intake duct 12.

[0052] As shown in figure 5, in the non-limiting example described herein the pump electric motor 20 is of the magnetic reluctance type. It comprises a casing 21, a stator 23 arranged inside the casing 21, and a rotor 24 arranged inside the stator 23.

[0053] The rotor 24 is coaxial to the axis A and is connected to the impeller 18.

[0054] A cooling chamber 25 having, at least in part, a substantially cylindrical shape is created between the pump body 22 and the casing 21.

[0055] The cooling chamber 25 extends around the casing 21.

[0056] The pump 10 also comprises an inlet duct 28 (figures 2 and 3) connected, at the opposite ends 28a and 28b thereof, to the cooling chamber 25 and to the delivery duct 14, respectively, and an outlet duct 30 (figures 2 and 4) connected, at the opposite ends 30a and 30b thereof, to the cooling chamber 25 and to the intake duct 12, respectively.

[0057] The inlet duct 28 is substantially straight and parallel to the axis A, and therefore substantially orthogonal to the delivery duct 14.

[0058] The outlet duct 30 comprises a first duct portion 31 connected to the cooling chamber 25 and a second duct portion 32 connected to the intake duct 12.

[0059] The first duct portion 31 and the second duct portion 32 are connected to each other at an intersection zone 30c.

[0060] The first duct portion 31 is substantially straight and parallel to the axis A, while the second duct portion 32 is substantially straight and orthogonal to the axis A and therefore substantially orthogonal to the intake duct 12.

[0061] The inlet duct 28 and the first duct portion 31 are substantially parallel to each other.

[0062] The inlet duct 28 is angularly offset with respect to the first duct portion 31 of the outlet duct 30 by an angle, measured at the axis A, less than 90°.

[0063] The cooling chamber 25 thus extends around the axis A over an angle greater than 270°. This angle is measured starting from the inlet zone 25a discussed herein below up to the outlet zone 25b discussed herein below.

[0064] In figures 1 and 2, the arrows Fl indicate the path travelled by the water in the intake duct 14, in the pressurisation chamber 15 and in the delivery duct 14.

[0065] An inlet zone 25a and an outlet zone 25b are defined in the cooling chamber 25. At the inlet zone 25a a part of the water pressurized in the pressurization chamber 15 enters the cooling chamber 25 through the inlet duct 28 after having been taken from the delivery duct 14 (arrow F2 in figure 2). At the outlet zone 25b the water circulating in the cooling chamber 25 (arrows F3 in figure 2) exits from the latter through the outlet duct 30 (arrow F4 in figure 2).

[0066] The end 28a of the inlet duct 28 is arranged at the inlet zone 25a and the end 30a of the first duct portion 31 is arranged at the outlet zone 25b.

[0067] As shown in figures 3 and 4, the pump 10 further comprises a compartment 34 in which an electronic control unit (not shown) of the pump 10 is housed. Alternatively, the electronic control unit may be arranged remotely, i.e. not included in the pump 10. In the example illustrated herein, the compartment 34 is arranged on the axially opposite side with respect to the pressurization chamber 15 and is adjacent to a bottom wall 35 of the pump 10.

[0068] The cooling chamber 25 is therefore arranged between the compartment 34 and the pressurization chamber 15.

[0069] In the non-limiting example shown in the figures, the pressurization chamber 15 is delimited, on the opposite side with respect to the pump electric motor 20, by a cover 38, shown in figure 1 and removed in figure 2.

[0070] In operation, the water enters in the pressurization chamber 15 through the intake duct 12 and travels through the pressurization chamber 15 by effect of the thrust exerted by the vanes 18a of the impeller 18, thus being pressurized. The pressurized water exits from the pressurization chamber 15 through the delivery duct 14. A part of the water that passes through the delivery duct 14 is taken and circulated in the inlet duct 28, then in the cooling chamber 25 and finally in the outlet duct 30, to be then re-introduced in the intake duct 12 and subsequently in the pressurization chamber 15.

[0071] During the circulation of the water in the cooling chamber 25, the water cools the stator 23.

[0072] Embodiments which are alternative to the one illustrated herein are provided, wherein the pump 10 is a volumetric pump (for example a scroll, gear, g-rotor, vane, piston pump, etc.) and / or wherein the pump electric motor is of the external rotor type, i.e. wherein the rotor is arranged inside the casing and outside the stator.

[0073] In general, the pump 10 may be any type of pump controlled by an electric motor that needs to be cooled. A person skilled in the art, in order to satisfy specific and contingent requirements, will be able to make numerous modifications and changes to the invention described above, which are however within the scope of protection of the present invention as defined by the following claims.

Claims

CLAIMS1. Electric water pump (10), comprising: a pump body (22); a pressurization chamber (15) defined inside the pump body (22); an intake duct (12) connected to the pressurization chamber (15); a delivery duct (14) connected to the pressurization chamber (15); a pump electric motor (20) configured to control the electric water pump (10), wherein the pump electric motor (20) comprises a casing (21), a stator (23) arranged inside the casing (21) coaxially to an axis (A) of the electric water pump (10) and a rotor (24) arranged inside the stator (23), or outside the stator (23) and inside the casing (21), coaxially to the shaft (A) of the electric water pump (10); a cooling chamber (25) made in the stator (23) or in the casing (21) of the pump electric motor (20) or in the pump body (22) or defined between the pump body (22) and the casing (21) of the pump electric motor (20);- an inlet duct (28) connected, at the opposite ends (28a, 28b) thereof, to the cooling chamber (25) and to the delivery duct (14), respectively, or to the cooling chamber (25) and to the pressurization chamber (15) at or close to the delivery duct (14), respectively;- an outlet duct (30) connected, at the opposite ends (30a, 30b) thereof, to the cooling chamber (25) and to the intake duct (12), respectively, or to the cooling chamber (25) and to the pressurization chamber (15) at or close to the intake duct (12), respectively;wherein said outlet duct (30) comprises a first duct portion (31) connected to the cooling chamber (25) and a second duct portion (32) connected to the intake duct (12) or to the pressurization chamber (15) at or close to the intake duct (12); wherein the first duct portion (31) is substantially parallel to the axis (A) and the second duct portion (32) is substantially orthogonal to the axis (A).

2. Electric water pump (10) according to claim 1, wherein the cooling chamber (25) has a substantially cylindrical shape.

3. Electric water pump (10) according to claim 1 or 2, comprising a compartment (34) in which an electronic control unit is housed, wherein the cooling chamber (25) is adjacent to the compartment (34).

4. Electric water pump (10) according to claim 3, wherein said compartment (34) is arranged at an end portion of the electric water pump (10) or alongside the casing (21) of the pump electric motor (20).

5. Electric water pump (10) according to any one of the previous claims, wherein the pump electric motor (20) is of the magnetic reluctance type.

6. Cooling circuit of a main engine or of a fuel cell or of a Power Unit, comprising an electric water pump (10) according to any one of the previous claims.

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