Pump for recirculating a cooling fluid for combustion engines with electric motor control device

Abstract

Pump for recirculating a cooling fluid for a vehicle with combustion engine, comprising: a pump body (11) designed to be fixed to a base (11a) of the vehicle engine; an impeller (1) inserted inside a chamber containing the cooling fluid and mounted on a driven shaft (2), at least one first electric motor (50) for driving the shaft (2) of the impeller (1), whereinsaid electric motor (50) comprises a fixed stator (51) mounted on the body (11) of the pump on the outside thereof and a rotor (52) radially outer lying with respect to the stator and connected to the shaft (2) of the impeller (1) of the pump on the outside of the cooling fluid chamber and via transmission means (54, 54a; 354, 354a; 54a, 66), and wherein the electric motor is designed to operate the impeller independently of the combustion engine.

Claims

1. A pump for recirculating a cooling fluid for a vehicle with a combustion engine, comprising: a pump body (11) designed to be fixed to a base (11a) of the combustion engine; an impeller (1) inserted inside a chamber containing the cooling fluid and mounted on a driven shaft (2); and at least one first electric motor (50) for driving the shaft (2) of the impeller (1), wherein said electric motor (50) comprises a fixed stator (51) mounted on the body (11) of the pump on an outside thereof and a rotor (52) radially outer lying with respect to the stator and connected to the shaft (2) of the impeller (1) of the pump on an outside of the cooling fluid chamber and via a transmission means (54,54a;354,354a;54a,66), and wherein the electric motor is designed to operate the impeller independently of the combustion engine.

2. The pump according to claim 1, wherein said transmission means comprises a flange (54) which has an annular edge (54a), extending parallel to the longitudinal direction X-X, and to which the rotor (52) is attached.

3. The pump according to claim 1, further comprising a fail-safe device.

4. The pump according to claim 3, wherein said fail-safe device comprises at least two pairs of windings on the poles of the stator (51) which are connected in parallel to a drive (70) which drives the motor.

5. The pump according to claim 3, wherein said fail-safe device comprises at least one friction coupling (60) arranged between means (3) for transmission of the movement from the shaft of the combustion engine and the shaft (2) of the pump impeller (1).

6. The pump according to claim 5, wherein said friction coupling (60) is of an electromagnetic type.

7. The pump according to claim 6, wherein said friction coupling (60) comprises an electromagnet (61) fixed to the pump body (11), a rotor (62) substantially in the form of a C arranged around the electromagnet (61) and connected to a sleeve (66) keyed onto the shaft (2) of the impeller (1); a circular ring (63) which is situated axially on an outside of the rotor (62) on an opposite side to the impeller (1) and which has, formed on its outer circumferential edge, a pulley (63a) suitable for engagement with a belt (3) for transmission of the movement from the shaft of the combustion engine, the ring (63) being fixed to a bearing (64) in turn keyed onto the said sleeve (66) integral with the shaft (2) of the impeller (1); an armature (65) arranged in front of the electromagnet (61) on the opposite side to the latter relative to the rotor (62) and connected to the ring (63) by means of a resilient membrane (65a) designed to allow movements of the armature in the axial direction, while preventing relative rotation thereof with respect to said ring.

8. The pump according to claim 7, wherein the rotor (62) of the coupling (60) is integral with a support (54a) of the rotor (52) of the electric motor (50).

9. The pump according to claim 8, wherein the rotor (62) of the coupling (60) is formed as one piece with said support (54a) of the rotor (52) of the electric motor (50).

10. The pump according to claim 3, wherein said fail-safe device comprises a second electric motor (150) mounted on the pump body (11) coaxially with the first motor (50) and driven by a second drive (170).

11. The pump according to claim 10, wherein said transmission means comprises a flange (354) which has an annular edge (354a), extending parallel to the longitudinal direction X-X, over a length such as to allow linking together of the two rotors (52,152).

12. The pump according to claim 1, wherein the one or more electric motors (50;150) are of a brushless type.

13. The pump according to claim 1, wherein a drive (70;170) of the one or more electric motors (50;150) comprises a twin-section configuration with a CPU (71) for controlling a first driver (72a) and a second driver (72b) for driving a respective first bridge (73a) and second bridge (73b).

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention, provided with reference to the accompanying drawings, in which:

(2) FIG. 1: shows a cross-sectional view along a vertical diametral plane of a first example of embodiment of a recirculating pump according to the present invention;

(3) FIG. 2: shows a view similar to that of FIG. 2 of a second example of embodiment of a recirculating pump according to the present invention;

(4) FIG. 3: shows a view similar to that of FIG. 1 of a third example of embodiment of a recirculating pump according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) As shown in FIG. 1 and assuming without a limiting meaning a pair of reference axes, i.e. a longitudinal axis X-X, for convenience coinciding with the axis of rotation of the the pump impeller shaft, and transverse/radial axis Y-Y, orthogonal to the longitudinal axis, the impeller 1 of a pump for recirculating the cooling fluid of vehicles and the like is located inside a chamber which, during use, contains the cooling fluid and is therefore defined as being a wet chamber; the impeller 1 is mounted on a first end of a shaft 2 housed in a fixed unit 10 comprising the pump body 11 in turn fixed to the base 11a of the vehicle engine.

(6) A sealing gasket 12, coaxial with the shaft 2, which ensures that the fluid inside the wet chamber is unable to seep out, and a bearing 13 on the inner race of which the impeller shaft 2 is keyed, are arranged inside the pump body 11.

(7) An electric motor 50 is keyed on the outside of the pump body 11: the radially inner stator 51 thereof is supported by the said pump body 11 and the rotor 52 thereof, radially on the outside of the stator 51, is connected to the drive shaft 2 of the impeller, on the outside of the wet chamber of the latter. In the example shown, the rotor 52 is connected via transmission means formed by a flange 54, comprising at least one arm 54a, extending parallel to the longitudinal direction X-X, to which the said rotor is attached.

(8) The electric power supply for the motor is provided via conductor wires 53 connected to an electric power source (not shown) of the motor.

(9) According to preferred modes of implementation it is envisaged that: the motor is of the brushless type with permanent magnets integral with the rotor 52 rotationally driven by means of suitable electrical energization of the stator windings; the motor 10 comprises at least two pairs of windings on the poles of the stator which are connected in parallel to a drive 70 which drives the brushless motor.

(10) The drive 70 may moreover comprise in turn a twin-section configuration with a CPU 71 which controls a first driver 72a and a second driver 72b for driving a respective first bridge 73a and second bridge 73b; in this way it is possible to provide a configuration known by the term fail-safe such that, in the event of malfunctioning or breakage of one of the windings and/or one of the sections of the drive 70, the other winding nevertheless becomes operative, guaranteeing the movement of the impeller 1 and therefore recirculation of the cooling fluid for the combustion engine.

(11) It is envisaged moreover that the two windings may comprise a different number of polarities in order to provide different torques, for example: a high torque for normal operation and low torque for fail-safe emergency operation.

(12) As shown in FIG. 2, a further embodiment of the cooling fluid recirculation pump is envisaged, said embodiment comprising a friction coupling 60 and control device of the electromagnetic type.

(13) In detail the friction coupling comprises: an electromagnet 61 fixed to the pump body 11; a substantially C-shaped rotor 62 which is arranged on the outside of the electromagnet 61 and is connected to a sleeve 66 keyed onto the shaft 2 of the impeller 1; a circular ring 63 which is situated axially on the outside of the rotor 62 on the opposite side to the impeller 1 and is suitably shaped and which has, formed on its outer circumferential edge, a pulley 63a suitable for engagement with a belt 3 for transmission of the movement from the shaft of the combustion engine; the ring 63 is fixed by means of screws 64a to a bearing 64 in turn keyed onto the said sleeve 66 integral with the shaft 2 of the impeller 1; an armature 65 arranged in front of the electromagnet 61 on the opposite side to the latter relative to the rotor 62 and connected to the ring 63 by means of a resilient membrane 65a designed to allow movements of the armature in the axial direction, but preventing relative rotation thereof with respect to the said ring.

(14) As shown, the radially outer axial arm 62a of the C-shaped rotor 62 is joined togetheror preferably formed as one piecewith the arm 54a supporting the rotor 52 of the electric motor 50.

(15) FIG. 3 shows a third embodiment of the pump according to the invention which envisages in this case: a first motor 50 with stator 51 keyed onto the pump body 11 and a second motor 150 with stator 151 keyed onto the pump body coaxially with the first motor 50; the rotor 52 of the first motor 50, situated radially on the outside of the stator 51, and the rotor 152 of the second motor 350, situated radially on the outside of the stator 151, are connected to the shaft 2 of the impeller 1 via transmission means formed by a flange 354 comprising at least one arm 354a extending, parallel to the longitudinal direction X-X, over a length such as to allow the two said rotors 52,152 to be linked together.

(16) The electric power supply for the motor is obtained conventionally via conductor wires 53 connected to an electric power source (not shown) of the motor.

(17) In the case of the motor 150 also, it is possible to provide fail-safe operation with twin stator windings which are controlled by a respective second drive 170 similar to the drive 70 for controlling the first motor 50 of the pump and therefore not described again in detail.

(18) The presence of the second motor 150 in addition to the first motor 50 allows, among other things, the overall dimensions and in particular the radial dimensions of said motors to be reduced, simplifying the assembly operations, and also allows the power consumption of each motor to be divided up compared to the power consumption of a single large-size motor.

(19) For all the configurations shown in FIG. 1, FIG. 2 and FIG. 3 the operation of the pump is as follows: under normal operating conditions, the supplying of a variable current to the stator 51 results in a magnetic field which, in concatenation with the permanent magnets of the rotor 52, causes rotation of the latter and therefore the flange 54 (FIG. 1) or rotor 62 (FIG. 2) or flange 354 (FIG. 3) which in turn operate the shaft 2 of the pump and therefore the impeller 1; in the event of malfunctioning and/or breakage of certain parts of the assembly the fail-safe device intervenes, this comprising: in the case of FIG. 1, intervention of either one of the two stator windings which is still active; in the case of FIG. 2, intervention of the friction coupling 60 which, by means of excitation of the electromagnet 61, recalls the armature 65, connecting the rotor 62 to the ring 63 and therefore to the combustion engine by means of the pulley 63a and the belt 3; in the case of FIG. 3, intervention of either one of the two motors 50,150.

(20) It is therefore clear how, with the pump according to the invention, it is possible to achieve effective recirculation of the vehicle cooling fluid, which may be varied depending on the actual requirement by means of suitable sizing/energization of the electric motor and with improved efficiency of the torque transmitted from the electric motor to the pump impeller 1, owing to the greater lever arm resulting from the radially outer arrangement of the rotor connected to the pump shaft.

(21) Moreover, owing to the provision of the motor rotor on the outside of the stator, in the preferred embodiment it is possible to obtain a single-piece connection to the pump shaft or to the rotor of the electromagnetic friction coupling, thus resulting in simplified machining and assembly as well as smaller masses and therefore a lower energy consumption both during production and when the pump is mounted on the combustion engine.

(22) In addition, the pump according to the invention ensures rotation of the impeller 1 also in the event of an electrical fault, thus avoiding stoppage of the vehicle before it reaches its destination.

(23) Although described in connection with a number of embodiments and a number of preferred examples of implementation of the invention, it is understood that the scope of protection of the present patent is determined solely by the following claims.