RU2446061C1 - Motowheel - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to vehicles and may be used in open space at extreme temperatures. Motowheel comprises case, motor and planetary reduction gear. Every planet pinion is made up of three wheels (8a, 8b, 9) fitted on common axle and coupled by elastically pre-strained elastically-compliant shafts 10. Outer surface of motor rotor 3 accommodates bushing 4 with ring element 5 that has cylindrical outer friction working surface interacting with outer friction working surface of central wheel 9 of each planet pinion. Motor stator 2 is arranged inside rotor 3. Motowheel case consists of two parts 6, 7, one part 6 is rigidly coupled with stator 2 while another one 7 may rotate. Inner surfaces of case parts are furnished with ring elements (11a, 11b) with inner friction working surfaces interacting with mating outer working surfaces of planet pinions (8a, 8b).

EFFECT: increased specific power output, possibility of operation in open space at temperatures approximating to 450 K.

4 cl, 5 dwg

Description

The invention relates to moving devices and can be used to propel various devices operating in open space and extreme temperature conditions.

Known electric motor wheel containing an electric motor, a planetary gear in the form of a 2K-H mechanism and a wheel hub [1].

A significant drawback of the known electric motor wheel is the limitation of 1500 ÷ 2500 rpm of the maximum values of the rotational speeds of the electric motor, due to the significant dynamic components of the load arising at high rotational speeds, and the small gear ratio implemented in one stage of the planetary gearbox. Together, this leads to large mass and size parameters of the electric motor-wheel. In addition, due to the need to create good lubrication conditions for a significant number of highly loaded rubbing mates, this design cannot be used in open space.

Of the known closest in technical essence to the proposed one is the electromotor wheel [2] selected as a prototype, comprising a housing, an electric motor and a planetary gear with a pinion gear, including a carrier with eccentric shafts rigidly connected to the stator of the electric motor, on the necks of which epicycloid satellites are placed, the sprocket introduced into engagement with the latter, mounted by means of bearings on the carrier, and the wheel hub, the electric motor-wheel is equipped with a central gear shaft d, rigidly connected to the rotor of the electric motor, mounted in the bearings of the carrier caps and engaged with involute satellites located on the root necks of the eccentric shafts, and also equipped with an overrunning clutch, the inner sprocket of which is made on part of the outer surface of the pinion wheel, the outer cage is aligned with the hub wheels, rollers are located in the nests of the separator, frictionally connected with the carrier, and bearings are located between the sprocket wheel and the wheel hub.

Significant disadvantages of this technical solution are:

- a gear ratio limited to 60 ÷ 80, realized in one stage of the planetary gearbox, low specific power (kW / kg) of the electric motor-wheel, due to limited 150 ÷ 200 rad / s electric motor revolutions and a significant mass of the gearbox, which together reduces the scope of its application in devices with increased requirements for weight and size parameters, for example, working in aerospace engineering;

- the impossibility of working in outer space and at temperatures above 350-370 K, associated with the need to create good lubrication conditions for a significant number of highly loaded rubbing joints of this design.

The objective of the invention is to increase the specific power of the electric motor wheel and expand the functionality of its use in extreme temperature conditions (up to 450 K) and in outer space.

This goal is achieved by the fact that in the electric motor wheel containing the housing, an electric motor with a rotor having an outer cylindrical surface, and a stator and a planetary gear including at least three satellites mounted uniformly around the circumference with the possibility of rotation around its axis in the circumferential direction, a wheel installed with the possibility of interaction with satellites, according to the technical solution, each of the satellites is made in the form of three pre-installed on one axis and interconnected with elastically deformed elasto-flexible shafts of the wheels with external friction working surfaces, and on the outer surface of the rotor there is a one-piece sleeve connected to it with an annular element having a cylindrical outer friction working surface mounted to interact with the outer friction working surface of the middle wheel of each satellite, an electric motor stator placed inside the rotor, while the body of the electric motor-wheel is made of two parts, one of which is rigidly with knitted with a stator, the other is mounted rotatably, while on their inner surfaces are annularly connected annular elements with internal friction working surfaces, mounted to interact with mating external friction working surfaces of the wheels of each satellite located on the side of the ends of the wheels, the value of δ (mm) of the preliminary elastic deformation of the elastic-flexible shafts of each satellite is

where T is the maximum moment created by the electric motor-wheel, N · m;

L is the length of the elastic shaft of the satellite, mm;

E is the modulus of elasticity of the material of the elastic ductile shaft of the satellite, MPa;

d is the diameter of the elastic shaft of the satellite, mm;

- расчетное среднее значение диаметров внутренних фрикционных рабочих поверхностей кольцевых элементов на соответственно неподвижной и подвижной частях корпуса, определяемое из конструктивных параметров электромотор-колеса, мм;

- the calculated average value of the diameters of the internal friction working surfaces of the ring elements on the respectively stationary and moving parts of the housing, determined from the design parameters of the electric motor-wheel, mm;

f is the coefficient of sliding friction in the joints of the friction working surfaces of the satellite wheels and the annular elements of the housing and the rotor hub;

n is the number of satellites.

In the electric motor-wheel, the wheels of each satellite are made with a barrel-shaped external working surface, the internal working surfaces of the ring elements of the body corresponding to them are torroidal, and the elastic-flexible shafts of each satellite are made with a diameter d selected from the relation

where [σ] - allowable stresses when bending the elastically flexible satellite shafts, MPa,

at the same time, at least two annular elements with internal friction working surfaces, each of which is installed with the possibility of interaction with the wheels of at least three satellites, are made on each part of the housing.

In the proposed technical solution, increasing the specific power and providing the possibility of using an electric motor wheel in extreme temperature conditions (up to 450 K) and in outer space is achieved as a result of the following:

- the transmission of torque from the engine to the rotating part of the housing is carried out not by gearing, but by means of frictional interaction of the corresponding working surfaces of the wheels of the satellites and ring elements;

- the position of the rotor axis is fixed relative to the stator axis in space directly by the satellites, the elastically flexible shafts of which are preliminarily elastically deformed, which allows excluding rolling bearings, radial and circumferential clearances and backlash from the design and, in combination, to ensure high smoothness of functioning of the interacting elements, which in combination with light aluminum alloys in the manufacture of the sleeve, the wheels of the satellites, the housing and the ring elements allows you to increase the speed of rotation of the engine I am up to 8-20 thousand revolutions per minute and due to this reduce its mass and dimensions by 4-5 or more times, moreover, not only 3, but also a significantly larger (6-18) number of satellites can be used in the design, which in total, it allows to increase the specific (kW / kg) power of the electric motor-wheel;

- the placement of the rotor of the electric motor inside the sleeve rigidly connected with it, as well as the placement of the stator inside the rotating rotor, allows to reduce the radial dimensions of the structure while increasing the efficiency of creating magnetic fields;

- the implementation of the wheels located on the side of the satellite ends with a barrel-shaped external working surface, and the internal working surfaces of the annular housing elements responding to them toroidal, allows for acceptable contact pressures with smaller radii and overall dimensions of the satellite wheels and the housing, while ensuring rational values of the radii r and R (r - the radius of the sphere into which the wheels of the satellites adjacent to the ends are “inscribed”, R is the radius of curvature of the ring elements on the housing in the axial section of the electric motor wheel, R> r) allows you to save the gear ratio during axial deformation and related displacements of the interacting transmission elements, and as an additional effect, reliable fastening of the moving components of the system relative to each other in the axial direction is achieved.

The dependence for determining the value of preliminary elastic deformation δ of the elastically flexible satellite shafts was obtained using known dependencies (see, for example, Darkov A.V., Shpiro G.S.Material resistance: Textbook for technical universities. - 5th ed., revised and enlarged - M .: Higher school, 1989 .-- 624 p .; pp. 266-270).

The elastic-flexible shafts of the satellites can be considered as cantilever fixed (on the middle satellite wheel) beams with a circular cross section of diameter d, loaded at the end with a concentrated load P, causing its deformation by δ, where

Since the magnitude of the greatest bending stresses in the round elastically compliant satellite shafts can be determined from the dependence

where W is the moment of resistance of the cross section of the elastically flexible satellite shaft,

then from the conditions of strength and ensuring a given effort of pressing the working surfaces

where J is the moment of inertia of the circular cross-section of the elastically flexible satellite shafts, J≈0.05d ⁴ , mm ⁴ ;

E is the modulus of elasticity of the material of the elastically flexible satellite shafts, MPa.

Figure 1 presents the electric motor-wheel; figure 2 is an enlarged view of the zone of interaction of the wheels of the satellites with the ring elements of the housing and the hub of the rotor; figure 3 - electric motor-wheel with two ring elements on each of the parts of the housing; figure 4 and 5 are sections respectively aa and bb of Fig.3.

The electric motor-wheel contains (Fig. 1) an axis 1 connected to a base (not shown) on which the stator 2 of the electric motor is permanently attached. The rotor 3 is made in the form of a hollow cylinder, inside which a stator 2 is placed. On the rotor 3 there is a sleeve 4 which is permanently connected to it and has an annular element 5. The annular element 5 has a cylindrical outer friction working surface (not shown) with a diameter D _B.

The body of the electric motor-wheel consists of two parts, one of which 6 is rigidly connected to the axis 1, the other 7 is mounted for rotation. Each of the transmission satellites (figure 1) is made in the form of three wheels located on the same axis:

- wheels 8a and 8b located on the side of the ends of the satellite, with barrel-shaped (fit into a spherical surface with a diameter d _T ) external friction working surfaces;

- the middle wheel 9, installed with the possibility of interaction with preloading normal to the contact surface with the outer cylindrical friction working surface of the annular element 5, due to the elastic deformation of the elastic shafts 10;

- rigidly connecting the wheel 9 with the wheels 8a and 8b of the elastic shafts 10 having a length L, diameter d and made, for example, of spring steel.

On the inner surface of the housing parts 6 and 7, annular elements 11a and 11b are located, having internal friction working surfaces, the toroidal profile of these surfaces is made with a radius greater than 0.5 d _T in axial section, and installed with the possibility of interaction with the external friction working surfaces of the wheels, respectively 8a and 8b with preloading normal to the contact surface.

The internal friction working surfaces (not shown) of the ring elements 11a and 11b the external friction working surfaces (not shown) of the wheels 8a, 8b, 9 and the ring element 5 have a friction coefficient f≥0.6, provided, for example, by Al ₂ O ₃ coating with a thickness 70 ÷ 100 μm, formed, for example, by anodic-cathodic microarc treatment on parts of the housing 6 and 7, wheels 8a, 8b, 9 and the ring element 5, which are made of aluminum alloys.

The toroidal surfaces of the annular elements 11a and 11b have a maximum diameter D _K1 . and D _K2 , the value of which is determined based on the following.

When the rotor 3 and the bushings 4 and the annular element 5 are rigidly connected with it and have a diameter D _B per revolution, the number of revolutions N of the middle wheel 9 having a diameter d _{C of} each satellite and each satellite as a whole is

The length of the arcs l on the surface with a diameter D _K1 connected to the axis 1 of the fixed part of the housing 6 and on the surface with a diameter D _K2 connected with the output shaft of the movable part of the housing 7, described by the contact line of the wheels located at the ends of the satellite, respectively 11 a and 11 b, are

The rotation angle γ (in radians) of the housing part 7 movable in the circumferential direction relative to the axis 1 of the electric motor-wheel is

Since the gear ratio u is

then

or

Insofar as

then

Taking into account expressions (15) and (17), the quantity D _KI can be determined from the relation

From here (subject to size minimization requirements)

Preliminary elastic deformation (of elastically flexible shafts of 10 satellites, providing the force required for transmitting torque to compress the friction working surfaces of the ring elements 5, 11a, 11b and, respectively, the wheels 8a, 8b, 9 to each other at each of the satellites is ensured by determining the values of D _K1 and D _K2 from dependences (16), (17), providing elastic deformation of the elastic shafts 10 by a value of 8 (see figure 1). Offset along the radii of diameters D _K1 and D _K2 (see figure 2) of the contact zone of the wheels 8a, 8b and the corresponding rings 11a and 11b, c that appear during radial deformation of the elastic shafts 10 are so insignificant that this practically does not lead to a change in the gear ratio. The movable part 7 of the housing is rigidly connected with the output shaft 12.

The electric motor-wheel is equipped with a separator 13 of an antifriction material having an annular shape. The holes (not shown) of the separators 13 enter with a radial clearance of the axle 14 of the wheels 8a and 8b (the axles 14 can be made in one piece with the resilient shafts 10).

If it is necessary to increase the reliability of the radial and axial base of the movable part 7 of the housing by creating additional radial bearings on the parts of the housing 6 and 7, at least two annular elements 11a ₁ , 11a ₂ displaced by an axial distance Δ relative to each other can be made (on parts 6 of the housing) and 11b ₁ , 11b ₂ (on the movable in the circumferential direction of the housing part 7) having internal friction working surfaces (Fig.3).

In this case, an additional group of at least three satellites, evenly spaced around the circumference of the satellites, whose wheels 8a ₂ and 8b _{2 are} mounted with the possibility of interaction with the corresponding ring elements 11a ₂ , 11b ₂ , and the middle wheel 9 '' with the annular element 5. The working friction surfaces of the annular elements 11a ₁ and 11b ₁ interact with the working friction surfaces of the wheels 8a ₁ and 8b _{1 of the} main satellite group, respectively. The middle wheel 9 '(Fig. 3) interacts with the annular element 5. The main and additional groups of satellites are axially displaced relative to each other by Δ (when creating three or more groups of annular elements, the number of satellite response groups increases accordingly). Each group consists of at least three satellites evenly spaced around the circumference, mounted in such a way that each subsequent satellite is axially displaced relative to the previous one by Δ (Figs. 3-5).

Transmissions are performed with gear ratios u = 500 ÷ 1000. The power supply of coils (not shown) of the stator 2 is carried out through an opening (not shown) in the axis 1. Bushing 4, wheels 8a, 8b, 9, housing parts 6 and 7 and ring elements 11a and 11b of the electric motor wheel are made of lightweight, for example aluminum alloys.

An example of calculating the parameters d, δ, D _K1 and D _K2 .

Initial data: d _C = d _T = 10 mm; D _B = 50 mm (determined by the design parameters of the engine); u = 500 (determined by the ratio of the required number of revolutions at the output and the number of revolutions of the engine); T = 80 Nm; L = 20 mm; E = 2.1 · 10 ⁵ MPa (the material of the elastic ductile shafts is spring steel); f = 0.9 (slip friction coefficient in the joints of friction working surfaces with oxide-ceramic on satellites and ring elements of the carrier bush and the body); n is 3; [σ] = 600 MPa (for the estimated life of 10,000 hours).

Then:

In the calculation, it is accepted that D _K1 <D _K2 (Fig. 2) for rotating the rotor 3 and the output shaft 12 in one direction (otherwise, the rotor 3 and the output shaft 12 will rotate in opposite directions).

The electric motor-wheel operates as follows.

The rotation with a speed of ω ₁ from the rotor 3, created by the stator 2 of the electric motor, is transmitted through frictional conjugation of the ring element 5 and the wheel 9 to the elastic-flexible shafts 10. From the elastic-flexible shafts 10 of each of the satellites, the rotation is transmitted to the wheels 8a, 8b. Wheels 8a and 8b as a result of frictional contact with the ring elements 11a and 11b, respectively, rolling around on their internal friction surfaces without sliding as a result of the difference in the diameters of the ring elements 11a and 11b, rotate the movable part 7 of the body with an angular velocity ω ₂ = ω ₁ / u in the forward (u> 0) or reverse (u <0) rotation of the rotor 3 direction. The electric motor-wheel construction shown in FIG. 3 works similarly. Moreover, the presence of several ring elements (11a ₁ , 11a ₂ and 11b ₁ , 11b ₂ ) provides reliable fixation of the movable part 7 of the housing when exposed to external radial loads (not shown).

Using the described design of the electric motor-wheel allows to increase the specific power in comparison with the existing ones by 2-3 or more times and to provide the possibility of working in open space at temperatures up to 450 K.

1. Rudenko V.N. Planetary and wave transmissions. Album designs. - M: Mechanical Engineering, 1980, p. 87, sheet 54. 2. Ibid., P. 88, sheet 55, scheme “a”. (71).

2. Patent RU No. 2098694, cl. IPC ⁶ F16H 1/32.

Claims (4)

1. An electric motor-wheel, comprising a housing, an electric motor with a rotor having an outer cylindrical surface, and a stator and a planetary gear including at least three satellites mounted uniformly around the circumference with the possibility of rotation around its axis in the circumferential direction, a wheel mounted with the possibility interaction with satellites, characterized in that each of the satellites is made in the form of three mounted on the same axis and interconnected by previously elastically deformed elastically flexible wheels with external friction working surfaces, and on the outer surface of the rotor a sleeve is permanently connected to it with an annular element having a cylindrical outer friction working surface mounted to interact with the outer friction working surface of the middle wheel of each satellite, the stator of the electric motor is located inside the rotor while the casing of the electric motor-wheel is made of two parts, one of which is rigidly connected to the stator, the other is installed with rotational axis, while on their inner surfaces there are annularly connected annular elements with internal friction working surfaces installed with the possibility of interaction with mating external friction working surfaces located on the side of the ends of the wheels of each of the satellites, while the value of δ (mm) is preliminary elastic the deformation of the elastically flexible shafts of each satellite is

where T is the maximum moment created by the electric motor-wheel, Nm;
L is the length of the elastic shaft of the satellite, mm;
E is the modulus of elasticity of the material of the elastic ductile shaft of the satellite, MPa;
d is the diameter of the elastic shaft of the satellite, mm;

- the calculated average value of the diameters of the internal friction working surfaces of the ring elements on the respectively stationary and moving parts of the housing, determined from the design parameters of the electric motor-wheel, mm;
f is the coefficient of sliding friction in the joints of the friction working surfaces of the satellite wheels and the annular elements of the housing and the rotor hub;
n is the number of satellites. 2. The electric motor-wheel according to claim 1, characterized in that the wheels of each of the satellites are made with a barrel-shaped outer working surface, and the inner working surfaces of the ring elements of the housing that respond to them are torroidal. 3. The electric motor-wheel according to claim 1 or 2, characterized in that the resilient shafts of each of the satellites are made with a diameter d selected from the ratio

where [σ] - allowable stresses when bending the elastically flexible satellite shafts, MPa. 4. The electric motor-wheel according to claim 1 or 2, characterized in that at least two annular elements with internal friction working surfaces are made on each part of the housing, each of which is installed with the possibility of interaction with the wheels of at least three satellites.

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