Hydraulic pump assembly

Abstract

The subject of the present invention is a hydraulic pump assembly (1), electromechanically actuated, for a braking system of a vehicle. The hydraulic pump assembly (1) comprises: i) a hydraulic piston (2); ID an electric motor (3), extending along an axis (X-X), comprising a stator (31) and a rotor (32) comprising permanent magnets (320); iii) a rotary-linear motion conversion device (4). Said rotary-linear motion conversion device (4) comprises: a hollow nut screw shaft (41) comprising a nut screw cavity (410) extending along the axis (X-X); a screw shaft (42) extending along the main axis (X-X), at least partially housed in the nut screw cavity (410), with a main end (421) operatively connected to the hydraulic piston (2); motion transmission means (43) comprising recirculating balls (430) adapted to transmit the rotary motion of the nut screw shaft (41) to the screw shaft (42) so as to move it in an axial direction along the axis (X-X). In accordance with the invention, said permanent magnets (320) are housed directly on the hollow nut screw shaft (41).

Description

"HYDRAULIC PUMP ASSEMBLY" DESCRIPTIONField of the invention

[0001] . The present invention relates to a hydraulic pump assembly, in particular electromechanically actuated . Said hydraulic pump assembly is suitable to be part of a braking system of a vehicle .

[0002] . The present invention also relates to a braking system of a vehicle comprising said electromechanical actuation .Prior art

[0003] . In the prior art electromechanically actuated hydraulic pump assemblies are known speci fically adapted to operate in braking systems for vehicles . Preferably, such application is present in vehicle braking systems of the brake-by-wire type .

[0004] . In detail , the known solutions of hydraulic pump assemblies comprise a hydraulic piston the movement of which is controlled by an electric motor by means of a rotary- linear motion conversion device . That is to say, said rotary-linear motion conversion device, receiving a rotary action, induced by the electric motor, converts it into a linear action which is discharged onto the hydraulic piston .

[0005] . In such solutions , a multiplicity of issues has been detected .

[0006] . The main issue is linked to the operativeconnection between the electric motor and the rotary-linear motion conversion device which, in the known solutions , is carried out by means of specific transmission components .

[0007] . A further issue of the solutions belonging to the prior art is linked to their dimensions , which in fact turn out to be particularly bulky, in particular along the axial development along a main axis , and also orthogonally to said main axis .Solution

[0008] . The purpose of the present invention is to provide a hydraulic pump assembly for a braking system of a vehicle configured to overcome at least some of the drawbacks highlighted in the prior art .

[0009] . These and other purposes are achieved by means of the hydraulic pump assembly according to claim 1 . These and other purposes are achieved by means of a braking system of a vehicle comprising the hydraulic pump assembly according to claim 8 .

[0010] . The dependent claims relate to preferred and advantageous embodiments of the present invention .Figures

[0011] . To better understand the invention and appreciate its advantages , some exemplary and non-limiting embodiments thereof will be described below, making reference to the accompanying figures , in which :

[0012] . - figure 1 is a schematic view of a hydraulic pumpassembly, along an axial section, according to an embodiment of the invention .Description of some preferred embodiments

[0013] . With reference to the figures , a hydraulic pump assembly according to the present invention is denoted by the number 1 .

[0014] . The present invention also relates to a braking system of a vehicle comprising said hydraulic pump assembly 1 .

[0015] . Preferably, said braking system of a vehicle is of the brake-by-wire type .

[0016] . In accordance with the present invention, the hydraulic pump assembly 1 is electromechanically actuated .

[0017] . According to the present invention, the hydraulic pump assembly 1 comprises a hydraulic piston 2 .

[0018] . According to the present invention, the hydraulic pump assembly 1 further comprises an electric motor 3 .

[0019] . Said electric motor 3 extends along an axis X-X, comprising a stator 31 and a rotor 32 .

[0020] . Preferably, the stator 31 is of the external stator type .

[0021] . The stator 31 comprises stator poles 310 obtained by means of suitable windings .

[0022] . Preferably, said rotor 32 is of the internal rotor type .

[0023] . The rotor 32 comprises permanent magnets 320 . Thepermanent magnets 320 constitute the rotor poles 310 .

[0024] . According to the present invention, the hydraulic pump assembly 1 further comprises a rotary-linear motion conversion device 4 .

[0025] . The rotary-linear motion conversion device 4 comprises a hollow nut screw shaft 41 , a screw shaft 42 housed inside said hollow nut screw shaft 41 , and motion transmission means 43 interposed between the hollow nut screw shaft 41 and the screw shaft 42 for transmitting the mutual motion .

[0026] . In accordance with the present invention, the hollow nut screw shaft 41 comprises a nut screw cavity 410 extending along the axis X-X .

[0027] . The hollow nut screw shaft 41 comprises an outer wall 411 and an inner wall 412 facing the nut screw cavity 410 and defining it .

[0028] . The screw shaft 42 extends along the main axis X-X, housed at least partially in the nut screw cavity 410 .

[0029] . The screw shaft 42 comprises a main end 421 operatively connected to the hydraulic piston 2 .

[0030] . Preferably, the screw shaft 42 also comprises a secondary end 422 also housed inside the nut screw cavity 410 .

[0031] . According to a preferred embodiment, the screw shaft 42 further comprises a screw outer wall 420 .

[0032] . According to a preferred embodiment, the inner wall411 and the screw outer wall 420 are operatively connected in such a way as to mutually transmit a motion .

[0033] . Said motion transmission means 43 are radially positioned between the hollow nut screw shaft 41 and the screw shaft 42 , adapted to transmit the rotary motion of the hollow nut screw shaft 41 to the screw shaft 42 so as to move it in an axial direction along the axis X-X .

[0034] . Said motion transmission means 43 comprise recirculating balls 430 interposed between the hollow nut screw shaft 41 and the screw shaft 42 .

[0035] . Preferably, the inner wall 411 and the screw outer wall 420 comprise respective threaded walls between which the aforesaid recirculating balls 430 operate .

[0036] . In accordance with the present invention, furthermore , said permanent magnets 320 are housed directly on the hollow nut screw shaft 41 .

[0037] . Preferably, therefore , the hollow nut screw shaft 41 and the rotor part of the electric motor 3 , by appropriately housing the permanent magnets 320 , are driven in rotation by the stator 31 : in this manner the hollow nut screw shaft 41 is directly driven in rotation . Preferably, therefore, the stator 31 directly drives the rotation of the hollow nut screw shaft 41 which houses the permanent rotor magnets 320 without any elements interposed between the two .

[0038] . In other words , the rotor 32 is obtained in thehollow nut screw shaft 41 , thus being an integral part of the rotary-linear motion conversion device 4 .

[0039] . According to a preferred embodiment, the hollow nut screw shaft 410 comprises the outer wall 411 and said permanent magnets 320 are engaged to said outer wall 411 .

[0040] . Preferably, the permanent magnets 320 are assembled in said outer wall 411 . Preferably, the permanent magnets 320 are embedded in said outer wall . Preferably, the permanent magnets 320 are co-moulded in said outer wall 411 .

[0041] . According to a preferred embodiment, the rotary- linear motion conversion device 4 comprises an anti-rotation member 45.

[0042] . Preferably, the anti-rotation member 45 is engaged with the screw shaft 42 , proximally to the main end 421 , and is adapted to slide axially avoiding relative rotation .

[0043] . Preferably, the anti-rotation member 45 comprises suitable sliding guides extending parallel to the main axis X-X .

[0044] . Preferably, the hydraulic piston 2 is operatively connected with said anti-rotation member 45 .

[0045] . According to a preferred embodiment , the hydraulic pump assembly 1 comprises an assembly body 6 suitable for housing and supporting the hollow electric motor 3 and the rotary-linear motion conversion device 4 .

[0046] . Preferably, said assembly body 6 also supports the hydraulic piston 2 .

[0047] . According to a preferred embodiment, the assembly body 6 comprises a pair of rolling elements 61, 62, preferably two ball bearings, engaged with the hollow nut screw shaft 410 to rotationally support it along the axis X-X.

[0048] . Preferably, the stator 31 is housed in the assembly body 6.

[0049] . According to a preferred embodiment, the hydraulic pump assembly 1 also comprises a magnetic element7 for detecting the position of the screw shaft 42.

[0050] . According to a preferred embodiment, said magnetic element 7 is engaged with the hollow nut screw shaft 41. Preferably, said magnetic element 7 is housed in the nut screw cavity 410. In other words, in accordance with the present invention, the magnetic element 7 is suitably sized to be housed in the nut screw cavity.

[0051] . According to a preferred embodiment, the magnetic element 7 is suitable for producing a varying magnetic field as a function of the rotation of the hollow nut screw shaft 41.

[0052] . Preferably, the magnetic element 7 is a permanent magnet .

[0053] . According to a preferred embodiment, the hydraulic pump assembly 1 further comprises a control board8 suitable for controlling the electric motor 3.

[0054] . Preferably, the control board 8 is operativelyconnected to the stator 31 and is suitable for controlling the actuation of the windings 310 of the stator 31.

[0055] . In accordance with a preferred embodiment, the control board 8 comprises a hall-effect sensor 80 suitable for detecting the magnetic field produced by the magnetic element 7.

[0056] . Preferably, said control board 8 is housed in and / or supported by the assembly body 6.

[0057] . Innovatively, the hydraulic pump assembly forming the subject of the present invention fully fulfils the intended purpose. Innovatively, also the braking system of a vehicle comprising said hydraulic pump assembly fully fulfils the intended purpose.

[0058] . Advantageously, the hydraulic pump assembly is of extremely compact dimensions.

[0059] . Advantageously, the hydraulic pump assembly is of extremely compact dimensions in the axial direction.

[0060] . Advantageously, the hydraulic pump assembly is of extremely compact dimensions in the radial direction.

[0061] . Advantageously, the hydraulic pump assembly features a direct connection between the electric motor and the rotary-linear motion conversion device.

[0062] . Advantageously, in the hydraulic pump assembly forming the subject of the present invention, the rotor of the electric motor is obtained directly on the nut screw shaft. Advantageously, the motion induced by the stator onthe rotor poles results in a direct motion of the hollow nut screw shaft . Advantageously, the nut screw shaft is functionally the component suitable to receive the rotary action induced by the stator, but at the same time is suitable to transmit the thrust action to the screw shaft .

[0063] . Naturally, the person skilled in the art will be able to make modifications or adaptations to the present invention, without however departing from the scope of the claims set forth below .LIST OF REFERENCES1 hydraulic pump assembly2 hydraulic piston3 electric motor31 external stator310 stator poles32 internal rotor320 permanent magnets4 rotary-linear motion conversion device41 hollow nut screw shaft410 nut screw cavity411 outer wall412 inner wall42 screw shaft421 main end422 secondary end43 motion transmission means430 recirculating balls45 anti-rotation member6 assembly body61 , 62 rolling elements7 magnetic element8 control board80 hall-effect sensorX-X main axis

Claims

CLAIMS1. A hydraulic pump assembly (1) , electromechanically actuated, for a braking system of a vehicle, comprising: i) a hydraulic piston (2) ; ii) an electric motor (3) , extending along an axis (X-X) , comprising a stator (31) , preferably external, and a rotor (32) , preferably internal, comprising permanent magnets (320) ; and iii) a rotary-linear motion conversion device (4) comprising :- a hollow nut screw shaft (41) comprising a nut screw cavity (410) extending along the axis (X-X) ;- a screw shaft (42) extending along the main axis (X-X) , at least partially housed in the nut screw cavity (410) with a main end (421) operatively connected to the hydraulic piston ( 2 ) ;- motion transmission means (43) comprising recirculating balls (430) radially positioned between the nut screw shaft (41) and the screw shaft (42) , suitable for transmitting the rotary motion of the nut screw shaft (41) to the screw shaft (42) to move it in an axial direction along the axis (X-X) ; wherein said permanent magnets (320) are housed directly on the hollow nut screw shaft (41) .

2. Hydraulic pump assembly (1) according to claim 1, wherein the hollow nut screw shaft (410) comprises an outer wall(411) , wherein said permanent magnets (320) are engaged, preferably assembled or embedded or co-molded, in said outer wall (411) .

3. Hydraulic pump assembly (1) according to any one of the preceding claims, wherein the rotary-linear motion conversion device (4) comprises an anti-rotation member (45) engaged with the screw shaft (42) , proximally to the main end (421) , suitable for sliding axially avoiding the relative rotation.

4. Hydraulic pump assembly (1) according to any one of the preceding claims, comprising an assembly body (6) suitable for housing and support the hollow electric motor (3) and the rotary-linear motion conversion device (4) .

5. Hydraulic pump assembly (1) according to claim 4, wherein the assembly body (6) comprises a pair of rolling elements (61, 62) , preferably two ball bearings, engaged with the hollow nut screw shaft (410) to rotationally support it along the axis (X-X) .

6. Hydraulic pump assembly (1) according to claim 4 or claim 5, also comprising a magnetic element (7) , wherein said magnetic element (7) is engaged with the hollow nut screw shaft (41) , housed in the nut screw cavity (410) , and is suitable for producing a varying magnetic field as a function of the rotation of the hollow nut screw shaft (41) .

7. Hydraulic pump assembly (1) according to claim 6, further comprising a control board (8) suitable for controlling theelectric motor (3) , wherein said control board (8) comprises a hall-effect sensor (80) suitable for detecting the magnetic field produced by the magnetic element (7) .

8. A braking system of a vehicle, comprising a hydraulic pump assembly (1) according to any one of the preceding claims .

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