EP1886962A1

EP1886962A1 - Hoist for elevator

Info

Publication number: EP1886962A1
Application number: EP05743474A
Authority: EP
Inventors: Takeshi Hatanaka
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2005-05-30
Filing date: 2005-05-30
Publication date: 2008-02-13
Anticipated expiration: 2025-05-30
Also published as: CN1984833A; EP1886962A4; EP1886962B1; CN1984833B; JPWO2006129338A1; KR20070065344A; KR100932587B1; JP4925104B2; WO2006129338A1

Abstract

An object is to provide a traction machine for elevators in that, despite motor's heat generation, heat distortion of a housing base is small.

To achieve the object, the machine comprises: the base having a tubularly formed cylindrical section, and a bottom section provided closing over one side of the cylindrical section; stator windings for a motor, the windings provided on the cylindrical section; a rotor for the motor, the rotor supported rotatably in the axial center of the base; a brake member disposed on the rotor; and a brake disposed on the base that correspondingly operates to brake on the brake member. At least one part of the bottom section is formed into a curved surface, in which the bottom section is formed with the curved surface protruding toward the rotor's mounted side. Thereby, high membrane stiffness of the bottom section is assured, and heat distortion of the base becomes small.

Description

TECHNICAL FIELD

The present invention relates to traction machines for elevators whose machinery is constructed with a housing base and a motor, the motor rotor is driven, and a brake is mounted on the base to brake rotation of the rotor.

BACKGROUND ART

A conventional traction machine used for an elevator is constructed with a first bearing stand and a second bearing stand, each of which has a bearing mounted thereon and is fixed onto a mounting bed; and a rotary shaft is pivotally attached to the first bearing stand and the second bearing stand. Then, a driving sheave disposed between the first bearing stand and the second bearing stand is mounted on the rotary shaft. On one end of the rotary shaft on the first bearing stand side, a rotor is mounted. A housing base that is constructed with the first bearing stand and a bowl-shaped frame with a planar bottom section, is provided on the first bearing stand; the base is mounted on the mounting bed. On the frame of the base, stator windings are mounted. Field magnets are disposed as opposed to the stator windings and mounted along the outer circumferential surface of the rotor; the rotor, the stator windings, and the field magnets compose the motor. Moreover, in an axial direction of the rotor, a brake member is extendedly formed; opposing the brake member a brake is mounted on the base whose brake shoes can be abutted on and released from, by means of an electromagnetic mechanism, both sides of the member in a radial direction. (For example, refer to Patent Document 1.)
[Patent Document 1] Japanese Laid-Open Patent Publication 1997-142761 (page 2, page 4, Fig. 2)

[Problems to be Solved by the Invention]

The conventional traction machine used for an elevator is driven by energizing the motor while the brake is in a state in which the brake shoes are made, by electromagnetic force, apart from the brake member keeping predetermined gaps. Because of this, the stator windings of the motor generate heat by repeating drive, and the base on which the stator windings are mounted is also heated by way of the heat conduction. The heating of the base is initiated by heat generation of the frame on which the stator windings are mounted, and the heat is transferred to the first bearing stand and the mounting bed; thus, it is also radiated from the surface of the first bearing stand and the mounting bed. For this reason, the base exhibits high-temperature distribution near the stator windings; meanwhile, parts of the first bearing stand and the mounting bed exhibit low-temperature distribution. In this way, a temperature gradient develops in the base. As a result, different thermal expansions develop in each of the parts, causing heat distortion of the base. The inventor has earnestly carried out further studies, and resultantly reached conclusions as follows: in a case in which a bottom section is formed in a simple shape, such as planar, as with the base described above, heat distortion of the base grows larger; and distortion of the brake shoes of the brake mounted on the base becomes relatively large with respect to the brake member.
Next, the reasons why the inventor has reached the conclusions described above will be explained. Fig. 9 shows an example of a traction machine used for an elevator, though it differs from that described in Patent Document 1, whose bottom section is formed in a planar shape such as the base described above. In Fig. 9, a housing base 31 has a cylindrical section 31a, a bottom section 31b formed in a planar shape and provided to close over one side of the cylindrical section 31a, and below it, a mounting section 31c to be mounted on a mounting pedestal not shown in the figure.
A bearing stand 2 is mounted on the mounting section 31c of the base 31, and at the center of the base 31 and the bearing stand 2, a rotor shaft 4 is supported, through a pair of bearings 3, rotatably clockwise or anticlockwise. A rotor 5 is fixed onto the rotor shaft 4. The rotor 5 has a rotor's cylindrical section 5a as opposed to the cylindrical section 31a, and a rotor's boss portion 5b provided on one side of the rotor's cylindrical section 5a; the rotor's boss portion 5b is fixed onto the rotor shaft 4. And then, the other side of the rotor's cylindrical section 5a is disposed as opposed to the bottom section 31b. The rotor 5 has a discoidal brake member 6 that is disposed adjacent to the other side 31d of the cylindrical section 31a, and is formed in radial directions extending beyond the rotor's cylindrical section 5a. The cylindrical section 31a, the brake member 6; and a driving sheave 7 are disposed in that order, and the driving sheave 7, adjoining the brake member 6, is fastened onto the rotor 5 by bolts 7a, detachable and reattachable toward the side opposite from the cylindrical section 1a. The driving sheave 7, is formed with rope grooves around its outer circumference, and a main rope 8 is wound around it to suspend elevator bodies such as a passenger car and a counterweight of the elevator.
A motor 9 is constructed of the rotor 5, stator windings 10 provided on the inner circumferential surface of the cylindrical section 31a, and field magnets 11 that are disposed correspondingly facing with the stator windings 10, and are provided on the outer circumferential surface of the rotor's cylindrical section 5a. The stator windings 10 and the field magnets 11 have predetermined gaps between them. On the outer circumferential surface of the base 31, brakes 12 are mounted in such a manner that they have two pairs of brake shoes 12a, each pair of which is constructed to be abutted on and released from respective sides of the brake member 6, in the axial directions. Each of the brakes 12 is provided inside with an electromagnetic mechanism, to separate each pair of brake shoes 12a from the brake member 6, and a pressing means to press each pair of brake shoes 12a against the same.
When an elevator is stopped, in the traction machine as constructed above, electric power supply to the stator windings 10 of the motor 9 is switched off, and simultaneously power to the electromagnetic mechanism of the brakes 12 is switched off; thus, the brake shoes 12a are pressed against the brake member 6 by the pressing means. The rotor 5, that is to say, the driving sheave 7 is braked. When the elevator starts operating, electric power is supplied to the stator windings 9, and simultaneously power is supplied to the electromagnetic mechanism of the brakes 12; therefore, the brake shoes 12a are separated from the brake member 6, against the pressure by the electromagnetic mechanism, in both axial directions of the brake member 6 so that gaps on both sides are held under equidistant conditions. Thereby, the pressure, by the brake shoes 12a, against the brake member 6 disappears; the rotor 5, that is to say, the driving sheave 7 is released from being braked, and simultaneously the driving sheave is driven. And then, by way of the main rope 8 wound around the driving sheave 7, the elevator bodies such as a passenger car and a counterweight of the elevator suspended by the main rope 8 not shown in the figure, are operated upward and downward.
Because of electric power supplied to the stator windings 10 of the motor 9, the traction machine generates heat uniformly along entire circumference of the stator windings 10. This generated heat is transferred to the cylindrical section 31a of the base 31, and then to the bottom section 31b and to the mounting section 31c; thus, the base 31 is heated, and the heat is radiated outside from the surface of the base 31.
In the next place, a temperature distribution in the base 31 in this state will be described. Because the cylindrical section 31a is located closest to the stator windings 10 that are heat generating parts, it exhibits higher temperatures than the bottom section 31b does. In addition, because in the lower location of the base 31, it has the mounting section 31c, heat in the cylindrical section 31a and the bottom section 31b is transferred by way of the mounting section 31c; thus, the heat is also radiated from the mounting section 31c. For this reason, the lower part of the base 31 exhibits lower temperatures than its upper part does by the quantity of heat that is conducted through and radiated from the mounting section 31c. In this way, a temperature gradient develops in the base 31 as described above; because of the temperature gradient, thermal expansions develop differently in each of the parts, which leads to heat distortion to develop in the base 31. The cylindrical section 31a exhibits high temperatures and its thermal expansion is large, which radially expands itself. However, because, on one side of the cylindrical section 31a the bottom section 31b is provided, and the amount of thermal expansion of the bottom section 31b is smaller than that of the cylindrical section 31a, the cylindrical section 31a is thermally distorted such that the other side 31d of the cylindrical section 31a radially expands; accordingly, the bottom section 31b is thermally distorted in a bow shape.
Here, this is equivalent to that force shown by the arrow "F" in Fig. 9 acts apparently on the other side 31d of the cylindrical section 31a in a radial direction. Therefore, it comes to that apparent bending-moment acts on the bottom section 31b. Fig. 10 is a diagram showing a state of heat distortion of the base 31. As shown in Fig. 10, apparent bending-moment acts on the bottom section 31b, and the base 31 is distorted aslant in a bow shape. And then, because an upper-most side of the base 31 exhibits higher temperatures, its thermal expansion is large; therefore, the closer to the upper-most side, the larger becomes heat distortion.
In this way, apparent bending-moment acts on the bottom section 31b; because, in a case of the traction machine shown in Fig. 9, the bottom section 31b is formed in a planar shape, the second moment of cross-sectional area, against bending, namely, membrane stiffness is small, so that distortion becomes large. In addition, because the upper-most side of the base 31 exhibits higher temperatures, its degree of distortion becomes large. Note that, the state of distortion shown in Fig. 10 is exaggerated for the purpose of providing an easy-to-understand explanation so that a degree of distortion is shown large differing from a real case.
By the way, when the elevator is in upward and downward operations, the brakes 12 have to hold the gaps separating the brake shoes 12a and the brake member 6 apart from each other (hereinafter referred to as a "brake gap"). However, if the base 31 is heat-distorted aslant in a bow shape due to the heat generation, the brakes 12 mounted on the base 31 undergo displacement with respect to the brake member 6 in an axial direction and become in an inclining state. Fig. 11(a) and Fig. 11(b) are diagrams showing a state of brake gaps in cases in which the base 31 is heat-distorted; Fig. 11(a) shows a state before heat distortion, and Fig. 11(b) does that after the heat distortion. Before the heat distortion, the brake gaps on both sides are held under equidistant conditions; however, after the heat distortion, the brakes 12 undergo displacement with respect to the brake member 6 in the axial direction and become in an inclining state. Thus, the brake shoes 12a mounted on each of the brakes 12 also undergo displacements in the axial direction and become in an inclining state. Because of this, the brake gaps are changed; a brake gap on one of the sides decreases. The larger becomes heat distortion of the base 31, the larger does the decreased amount of the brake gap, as well.
On the other hand, when the brakes 12 are mounted in lower locations of the base 31 in which heat distortion is small, the decreased amount of the brake gap becomes small. However, it becomes practically impossible to mount the brakes 12 in the lower locations of the base 31 because their maintenance inspection is difficult when the brakes 12 exist in the lower locations, and mounting spaces for the brakes 12 are limited because the mounting section 31c is formed in the lower locations of the base 31.
As described above, the traction machine for an elevator is driven in its initial state before heat generation with the brake shoes 12a being kept, with predetermined gaps, apart from the brake member 6; however, heat distortion of the base 31 due to generated heat becomes large since then; and distortion of the brake shoes 12a becomes relatively large with respect to the brake member 6. As a result, the decreased amount of the brake gaps becomes also large. Because of this, the brake shoes 12a come into contact with the brake member 6, which, in upward and downward operations, causes problems in that dragging sounds are emitted due to the brake shoes 12a abutting on the brake member 6, or the brake shoes 12a wear down. Nevertheless, in expectation of the decreased amount of brake gaps, when the brake gaps are set to be large in their initial state before heat generation, strokes of the brake shoes 12a also become large. In this case, when braking, an impact by the brake shoes 12a colliding with the brake member 6 becomes large, so that noise becomes large. And then, when releasing the braking, problems occur in that an electromagnetic force to separate the brake shoes 12a from the brake member 6 becomes large, so that the capacity of the brakes 12 tends to be also large.
The present invention has been directed at solving these problems, and an object of the invention is to provide a traction machine for elevators in that, despite motor's heat generation, heat distortion of a housing base becomes small.

[Means for Solving the Problems]

In one aspect of this invention, a traction machine for elevators comprises: a base having a tubularly formed cylindrical section, and a bottom section provided closing over one side of the cylindrical section; stator windings for a motor, the windings provided on the cylindrical section; a rotor for the motor, the rotor supported rotatably in the axial center of the base; a brake member disposed on the rotor; and a brake disposed on the base that correspondingly operates to brake on the brake member; the traction machine is characterized in that at least one part of the bottom section is formed into a curved surface, wherein the bottom section is formed with the curved surface protruding toward the rotor's mounted side.

[Effects of the Invention]

According to the present invention, at least one part of the base's bottom section is formed into a curved surface, wherein the bottom section is formed with the curved surface protruding toward the rotor's mounted side. Thus, high membrane stiffness of the base can be assured. For this reason, despite the motor's heat generation, heat distortion of the base becomes small.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a cross-sectional diagram showing a traction machine for an elevator in Embodiment 1 of the present invention;
Fig. 2 is a front diagram viewed in the direction of the arrow "II" in Fig. 1;
Fig. 3 is a diagram showing a relationship between the radius of a bottom section and the amount of brake gaps decreased owing to heat distortion;
Fig. 4(a), Fig. 4(b), Fig. 4(c) and Fig. 4(d) are diagrams each showing the circumferential mounting location of brakes of a traction machine for an elevator in Embodiment 2 of the present invention;
Fig. 5 is a diagram showing a relationship between the circumferential brake-mounting locations and the amount of brake gaps decreased owing to heat distortion;
Fig. 6 is a diagram showing preset brake gaps with respect to radii of a spherical bottom section and brake-mounting locations;
Fig. 7(a) and Fig. 7(b) are diagrams each showing an application example of a traction machine for an elevator in Embodiment 2 of the present invention;
Fig. 8 is a cross-sectional diagram showing a traction machine for an elevator in Embodiment 4 of the present invention;
Fig. 9 is a cross-sectional diagram showing a traction machine for an elevator in which a base's bottom section is in a planar shape;
Fig. 10 is a diagram showing a state of heat distortion of the base in Fig. 9;
Fig. 11(a) and Fig. 11(b) are diagrams showing a state of brake gaps in cases in which the base in Fig. 9 is heat-distorted; and
Fig. 12 is a table showing comparative cases in which the bottom section 1b is formed into either a circular conic or spherical shape.

[Explanation of Numerals and Symbols]

"1" is a base; "1a," cylindrical section; "1b," bottom section; "1d," spherical section; "1f," boundary portion; "5," rotor; "6," brake member; "7," driving sheave; "7a," bolts; "8," main rope; "9," motor; "10," stator windings; "11," field magnets; "12," brakes; "12a," brake shoes; "14," passenger car; "15," counterweight; "31," base; "31a," cylindrical section; "31b," bottom section; "50," base; "50a," cylindrical section; "50b," bottom section; "50d," spherical section; "50e," [text missing] "50f," boundary portion; "50g," spindle; "52," rotor; "53," brake member; "54," driving sheave; and "55," bolts.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, preferable embodiments of the present invention will be explained by referring to drawings.

Embodiment 1.

Fig. 1 and Fig. 2 are diagrams showing a traction machine for an elevator in Embodiment 1 of the present invention; Fig. 1 is a cross-sectional diagram, and Fig. 2 is a diagram viewed in the direction of the arrow "II" in Fig. 1. In the figures, the same reference numerals and symbols designate the same or corresponding items in Fig 9. The traction machine has a base 1, where the base 1 has a cylindrical section 1a having a tubular form, a bottom section 1b placed to close over one side of the cylindrical section 1a, and below it, a mounting section 1c to be mounted on a mounting pedestal not shown in the figures. The bottom section 1b is formed into a partially spherical section 1d, and the spherical section 1d is formed to protrude on one side in a direction toward a rotor 5. A boundary portion 1f between the cylindrical section 1a and the bottom section 1b is formed into an arc shape, and one edge of the arc shape and one edge of the spherical section 1d of the bottom section 1b are continuously joined together. In the central part of the bottom section 1b, a bottom boss-portion 1e is provided to fix a bearing 3; and the spherical section 1d is formed between the parts starting from one edge of the arc shape of the boundary portion 1f and the bottom boss-portion 1e. And then, in the bottom section 1b, the part that has the spherical section 1d is formed to have a uniform thickness. The spherical section 1d has its center C positioned on the axial center line outside the base 1, and is objectively formed with respect to the axial center line of the base 1. The radius of the spherical section 1d is determined such that the vertex of the spherical section 1d is positioned at the dimension S from the outer edge of the base 1. Therefore, the radius of the spherical section 1d becomes smaller whenever the dimension S becomes larger, and the radius becomes larger whenever the dimension S becomes smaller. Brakes 12 each are mounted on the base 1 in the circumferential directions; they are mounted at an angle of approximately 45° with respect to the horizontal center of the base 1, and above the horizontal center. And then, similarly to the traction machine for an elevator in Fig. 9, by supplying electric power to stator windings 10 of a motor 9, the elevator bodies are operated upward and downward.
Because of electric power supplied to the stator windings 10, the stator windings 10 generate heat. This generated heat is transferred to the cylindrical section 1a, the bottom section 1b and then to the mounting section 1c; thus, the base 1 is heated, and the heat is radiated outside from the surface of the base 1. The heating of the base 1 exhibits high temperatures at the cylindrical section 1a near the stator windings 10; meanwhile, the bottom section 1b and the mounting section 1c exhibit lower temperatures than the cylindrical section 1a. In this way, a temperature gradient develops at each of the parts in the base 1; because of thermal expansions that differently develop at each of the parts due to the temperature gradient, heat distortion develops in the base 1. However, in the traction machine for an elevator in the embodiment of the present invention, the bottom section 1b is formed with the partially spherical section 1d; and when the spherical section 1d is formed to protrude in the direction toward the other side 1d of the cylindrical section 1a, high membrane stiffness of the bottom section 1b is assured, so that heat distortion of the base 1 becomes small. When the heat distortion of the base 1 becomes small, displacement of the brakes 12 mounted on the base 1 with respect to a brake member 6 also becomes small; as a result, the decreased amount of brake gaps becomes small.
Next, a relationship between the radius of the spherical section 1d and the amount of brake gaps decreased owing to the heat distortion will be described by using Fig. 3. As shown in Fig. 3, whenever the radius of the spherical section 1d becomes smaller, its membrane stiffness becomes higher, so that heat distortion becomes smaller; as a result, the decreased amount of brake gaps becomes smaller. On the contrary, whenever the radius of the spherical section 1d becomes larger, namely when it asymptotically becomes in a planar shape, its membrane stiffness becomes lower, so that the heat distortion becomes larger; as a result, the decreased amount of brake gaps becomes larger. When a bottom section comes into a planar shape, the decreased amount of brake gaps becomes the largest. In this way, the bottom section 1b is formed with the partially spherical section 1d; and when the spherical section 1d is formed to protrude in the direction toward the other side 1d of the cylindrical section 1a, the amount of brake gaps decreased owing to the heat distortion becomes small. Thus, the smaller the radius of the spherical section 1d becomes, the smaller does the decreased amount.
The smaller becomes the radius of the spherical section 1d, the smaller does the decreased amount of brake gaps; however, when the radius of the spherical section 1d becomes too small, the recessed amount of the bottom section 1b, namely the dimension S in Fig. 1 becomes large. As a result, the width of the traction machine in an axial direction also becomes large. In order to construct the traction machine without enlarging the width in the axial direction, as shown in Fig. 1, it is preferable for the bottom section 1b to form the spherical section 1d in such a way that the dimension S is set to become approximately equal to the width of the cylindrical section 1a in the axial direction.
Next, a comparison will be described between such the bottom section 1b formed into a circular conic shape and such the one formed into the spherical section 1d as in the embodiment of the present invention. In the embodiment of the present invention, the bottom section 1b is formed into the spherical section 1d; however, it may be possible to form into a circular conic shape, so as to protrude in the direction toward the other side 1d of the cylindrical section 1a. However, the decreased amount of brake gaps becomes smaller when the spherical section 1d is formed than when the circular conic shape be.
The table in Fig. 12 shows comparative cases in which the bottom section 1b is formed into either a circular conic or spherical shape, which represents an example of an analytical result of the decreased amount of brake gaps when one of the brakes 12 is mounted at the top of the base 1 at an angle of 90° with respect to the horizontal center, and heat distortion develops in part, excluding the mounting section 1c, in the cylindrical section 1a and the bottom section 1b of the base 1. In the table, "D" is the outside diameter of the cylindrical section; "L," the width of the cylindrical section; "S," a distance between the vertex of the spherical shape and the outer edge of the base 1, or the one between the vertex of the circular conic shape and the outer edge of the base 1; "H," the height of brake shoes 12a; "t," the board thickness of the bottom section 1b; "ΔT," a temperature rise at the cylindrical section 1a caused by generated heat in the stator windings 9; and "δ-ratio," a ratio of the decreased amount of brake gaps in a case of the cylindrical shape compared to the decreased amount of brake gaps in a case of the circular conic shape that is set as 1. Note that, material for the base 1 is cast iron usually applied to traction machines; and the analysis has been carried out by analysis software "ANSYS." Here, "D," "L," "S," and "H" described above are shown in Fig. 1.
As shown in the table in Fig. 12, when the bottom section 1b is formed into the spherical shape, the decreased amount of brake gaps can be made some 40% smaller than that of the circular conic shape, and thus more effective.
As described above, a traction machine for an elevator in the embodiment of the present invention comprises: a base 1 having a tubularly formed cylindrical section 1a, and a bottom section 1b provided to close over one side of the cylindrical section 1a; stator windings 10 for a motor 11, the windings provided on the cylindrical section 1a; a rotor 5 for the motor 11, the rotor supported rotatably in the axial center of the base 1; and brakes 12 disposed on the base 1 for braking the rotor 5. Then, at least one part of the bottom section 1b is formed into a partially spherical section 1d, and the spherical section 1d is formed to protrude on one side in the direction toward the rotor 5. Therefore, high membrane stiffness of the base 1b can be assured, even when electric power is supplied to the stator windings 10, and the base 1 is heated, its heat distortion becomes small; as a result, the decreased amount of brake gaps of the brakes 12 becomes small. Because of this, it rarely occurs in a rotating state that dragging sounds are emitted due to the brake shoes 12a abutting on a brake member 6, and the brake shoes 12a wear down.
In addition, in order to avoid contacting of the brake shoes 12a with the brake member 6 even when the base 1 is heated, in an initial state before the base 1 is to be heated, and in expectation of the decreased amount of brake gaps owing to heat distortion, a brake gap is set to its initial state (hereinafter referred to as a "preset brake gap"). Because in the traction machine for an elevator in the embodiment of the present invention, the decreased amount of brake gaps owing to heat distortion is small, the preset brake gap can also be set small; when braking, impact by the brake shoes 12a colliding with the brake member 6 becomes small, so that noise becomes small. And then, when releasing the braking, an electromagnetic force to separate the brake shoes 12a from the brake member 6 becomes small, so that the capacity of the brakes 12 can also be made smaller.
Moreover, membrane stiffness of the bottom section 1b becomes high, and an overall membrane stiffness of the traction machine becomes also high, so that it is possible to achieve not only the decreased amount of heat distortion, but also smaller distortion against loads of a passenger car and a counterweight that the traction machine suspends.
Note that, in the embodiment of the present invention, the bottom section 1b is formed into the spherical section 1d; however, it may not be necessarily formed into the spherical section 1d. For example, at least one part of the bottom section 1b may be formed into a curved surface continuously composed of surfaces having different radii of curvature; that is, instead of a circular conic shape, it may be formed with a curved surface. Even in such a configuration, heat distortion can become small, and the decreased amount of brake gaps can become small. Although the spherical section 1d has its center positioned on the axial center line outside the base 1, this is not necessarily the case. As long as the bottom section 1b is formed into a partially spherical surface, the center may be positioned off the axial center line of the base 1. In addition, although the spherical section 1d of the base 1 is objectively formed with respect to the axial center line of the base 1, this is not necessarily the case of being objectively formed. Even if a spherical surface or a curved surface is formed only on the upper side of the base 1 having large heat distortion, the decreased amount of brake gaps can become small. However, by forming the spherical surface or the curved surface objectively with respect to the axial center line of the base 1, and by forming the spherical surface or the curved surface also in the respective under-side of the base 1, heat distortion can become smaller, so that the decreased amount of brake gaps can become small. Moreover, because the spherical section 1d of the bottom section 1b has its center positioned on the axial center of the base 1, and is objectively formed with respect to the axial center, when the base 1 is manufactured by casting, it is possible to obtain an elevator traction machine in that it is easy to manufacture its cast mold.
In addition, because the boundary portion 1f between the cylindrical section 1a and the bottom section 1b is formed into an arc shape, and one edge of the arc shape and that of the spherical section of the bottom section 1b are continuously joined together, there exists no planar part, so that membrane stiffness will be further enhanced; smaller heat distortion can be achieved.
In addition, in the embodiment of the present invention, although the thickness of the spherical section 1d in the bottom section 1b is configured to be uniform, the thickness of the spherical section 1d is not necessarily uniform. However, in a shape in which this thickness largely varies, a temperature gradient develops in the thickness directions; that leads to heat distortion. Because of this, in the embodiment of the present invention, the thickness of the spherical section 1d of the bottom section 1b is formed to be uniform, so that heat distortion can become smaller; it is possible to obtain a lightweight and highly-stiff traction machine for an elevator.
By the way, an elevator operates, by way of a main rope 8 wound around a driving sheave 7, by driving the driving sheave 7, its elevator bodies such as a passenger car and a counterweight suspended by the main rope 8 on its both ends, to move upward and downward. The driving sheave 7 is driven under the conditions that loads of the elevator bodies are acting on each other by way of the main rope 8. Under the loads acting on the driving sheave 7 by way of the main rope 8, when upward and downward operations continue for a long years, because of wear down of the driving sheave 7, or damage to the driving sheave 7 caused by biting-in of foreign material between the driving sheave 7 and the main rope 8, or the like, it sometimes becomes necessary to replace the driving sheave 7 of the traction machine with a new one. In the embodiment of the present invention, because the driving sheave 7 is detachably and reattachably fastened onto the rotor 5, even in cases of unforeseen events described above, without replacing the driving sheave 7 with a new one by exchanging the traction machine, it is possible to replace the driving sheave 7 from the existing traction machine.
Furthermore, a brake member 6 is disposed adjacent to the other side 1d of the cylindrical section 1a, and is discoidally formed radially extending beyond the outer circumference of the rotor 5; the brakes 12 corresponding to the discoidal brake member 6 are mounted on an outer circumferential surface of the base 1; and the driving sheave 7 is disposed adjacent to the brake member 6 in the order going from the cylindrical section 1a to the brake member, and is detachably and reattachably fastened onto the rotor 5 toward the side opposite from the cylindrical section 1a. Therefore, its axial width can be shortened, and it is possible to obtain a lightweight traction machine for an elevator. At the same time, the driving sheave 7 can be replaced without removing the brakes 12; as a result, person-hours for replacing the driving sheave 7 can be shortened.

Embodiment 2.

Fig. 4(a), Fig. 4(b), Fig. 4(c), Fig. 4(d), Fig. 5, and Fig. 6 are diagrams for describing another embodiment of the present invention. In a traction machine for an elevator in Embodiment 1 of the present invention, the bottom section 1b is formed into the partially spherical section 1d, so that the amount of brake gaps decreased owing to heat distortion is made small. And then, the brakes 12 each are mounted on the upper side of the base 1 at an angle of approximately 45° with respect to the horizontal center of the base 1, in its circumferential directions. As described above, brake gaps in their initial state before the base 1 is to be heated (namely, "preset brake gaps") are set in expectation of the decreased amount of brake gaps owing to heat distortion; thus, it is desirable for the preset brake gaps to be set as small as possible. In addition, it is essential to set desired preset brake gaps for any arbitrary locations of the brakes 12. In the embodiment of the present invention, in comparison with the traction machine for an elevator in Embodiment 1, brakes 12 each are disposed at arbitrary locations in the circumferential directions; and then, setting methods of the preset brake gaps are described, based on relationships among the decreased amount of brake gaps owing to heat distortion, circumferential mounting locations of the brakes 12, and the radius of the spherical section 1d.
Fig. 4(a), Fig. 4(b), Fig. 4(c) and Fig. 4(d) are diagrams each showing the circumferential mounting locations of the brakes 12, in which the brakes 12 are shown being mounted on the upper side at various angles with respect to the horizontal center of the base 1. Fig. 5 is a diagram showing a relationship between circumferential mounting locations of one of the brakes 12 and the amount of brake gaps decreased owing to heat distortion. As described before, the closer to the upper-most side of the base 1, the larger exhibited is the amount of heat distortion. For this reason, when an angle of the circumferential mounting location of one of the brakes 12 becomes large as shown in Fig. 4(a), Fig. 4(b), Fig. 4(c) and Fig. 4(d), the decreased amount of brake gaps owing to heat distortion becomes also large as shown in Fig. 5. In addition, the decreased amount of the brake gap becomes larger whenever the radius of the spherical section 1d becomes larger, namely whenever it asymptotically comes into a planar shape.
As described above, the decreased amount of the brake gap owing to heat distortion varies depending on the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12. For this reason, it is necessary to determine how to set a preset amount of the preset brake gaps based on the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12. It is thus necessary to determine preset brake gaps, while keeping the minimum necessary amount of the brake gap under heat distortion in the base 1, to be strokes of the brake shoes 12a, taking into consideration the capacity of the brakes 12 and noise from the brake shoes 12a caused when they are pressed. That is to say, based on the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12, in expectation of the decreased amount of brake gaps owing to heat distortion of the base 1, the preset brake gaps are set at a desired value so that the capacity of the brakes 12 and noise from the brake shoes 12a are minimized as small as possible.
Fig. 6 is a diagram showing a relationship between circumferential mounting locations of one of the brakes 12 and the amount of preset brake gaps, at various radii of the spherical bottom section 1d. As shown in Fig. 6, when an angle of the mounting location of one of the brakes 12 becomes smaller, namely, whenever it is mounted in the lower locations of the base 1, and whenever the radius of the spherical part 1d becomes smaller, the preset brake gap is set smaller. That is, because the preset brake gap is set in expectation of the decreased amount of brake gaps, the smaller becomes the decreased amount of the brake gaps, the smaller can be set the preset brake gap.
Here, setting methods of the preset brake gap will be described based on the decreased amount of brake gaps owing to heat distortion, and on a relationship between the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12. For example, the circumferential mounting location of one of the brakes 12 is set at an angle of 30°, and when the preset brake gaps are desired to be set at "A," the base 1 should be formed so that the radius of the spherical section 1d becomes 'a.' The smaller becomes the radius of the spherical section 1d, the smaller does the decreased amount of brake gaps; however, when the radius of the spherical section 1d becomes too small, the recessed amount of the bottom section 1b, namely the dimension S in Fig. 1 becomes large. As a result, the width of the traction machine in an axial direction also becomes large. For this reason, in order to configure the traction machine without increasing its width in the axial directions, a dimensional limitation is imposed on the vertex of the spherical section 1d (the dimension S in Fig. 1); for example, the base 1 should be formed so that the radius of the spherical section 1d becomes 'b.' In this case, when the preset brake gap is desired to be set at "B," the circumferential mounting location of one of the brakes 12 should be set at an angle of 45°. As described above, the preset brake gap is set at a desired value based on the decreased amount of brake gaps owing to heat distortion, and on the relationship between the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12.
As described above, the preset brake gap is set based on the decreased amount of brake gaps owing to heat distortion, and on the relationship between the radius of the spherical section 1d and the circumferential mounting location of one of the brakes 12. However, when the brake shoes 12a are mounted in both sides of the brake member 6 as opposed thereto in the embodiment of the present invention, there exists some cases in which a brake gap on one of the sides decreases, but one on the other side increases by the amount that the former has been decreased. In this case, it may be possible to set the preset brake gaps by taking the increased amount of brake gaps owing to heat distortion into consideration. In this way, in the embodiment of the present invention, it may be possible to set the preset brake gap based on, not only the decreased amount of brake gaps, but also the increased amount of them, namely, on the amount of their change taken into consideration.
As described above, the embodiment of the present invention includes, brakes 12 mounted along the circumference of a base 1, and brake shoes 12a, while maintaining brake gaps with respect to the brake member 6, for abutting thereon and releasing therefrom; wherein the base 1 is heat-distorted under heat generated in stator windings 10 due to current being passed through them, and based on this varying amount of the brake gaps owing to heat distortion, and on the relationship between the radius of the spherical surface 1d and the circumferential mounting locations of the brakes 12, preset brake gaps are set. Therefore, degrees of freedom in locating the brakes 12 are increased, and in their arbitrary locations, preset brake gaps are set in expectation of the amount of change of the brake gaps. It is thus possible to obtain such a traction machine for an elevator in which dragging sounds from the brake shoes 12a, and wear down of the brake shoes 12a rarely occur, and when braking, colliding sounds by the brake shoes 12a become small. Moreover, even when the width of the traction machine in an axial direction has a dimensional limitation, it is similarly possible to obtain such an elevator traction machine in which dragging sounds from the brake shoes 12a, and wear down of the brake shoes 12a rarely occur, and when braking, colliding sounds by the brake shoes 12a become small.

Embodiment 3.

Fig. 7(a) and Fig. 7(b) are diagrams showing another embodiment of the present invention. In the embodiment of the present invention, a traction machine for an elevator in Embodiment 2 is applied to an elevator; depending on locations of brakes 12, a variety of applications are shown.
In Fig. 7(a), the traction machine is fixed on a mounting pedestal 13a mounted either on the top of a hoistway or in a machine room. The main rope 8 wound around the driving sheave 7 suspends on one end thereof a passenger car 14 as an elevator body, and on the other end a counterweight 15 as the same elevator body. In order to avoid interference, in the hoistway, between the passenger car 14 and the counterweight 15, a deflector sheave 16 is mounted on the mounting pedestal 13a at a predetermined distant location spaced from the driving sheave 7. The main rope 8 is paid out at an angle from the driving sheave 7, is wound around the deflector sheave 16, and suspends the counterweight 15; then, the passenger car 14 and the counterweight 15 are disposed maintaining a predetermined spacing from each other. According to drive by the traction machine, the driving sheave 7 starts rotating, so that the passenger car 14 and the counterweight 15 are raised and lowered each other in a jig-back way. In the elevator described above, in order to avoid interference with the main rope 8 paid out at an angle from the driving sheave 7, the brakes 12 each of the traction machine are mounted at an angle of approximately 45° with respect to the horizontal center.
And then, in a manner similar to Embodiment 2, a preset brake gap is set at a desired value based on the decreased amount of brake gaps owing to heat distortion, and on the relationship between the radius of the spherical section 1d and the circumferential mounting locations of the brakes 12 each (namely, the mounting locations at an angle of approximately 45° with respect to the horizontal center).
In a case of an elevator in Fig. 7(b), the traction machine is fixed on the mounting pedestal 13b located on the lower part of the hoistway. The main rope 8 wound around the driving sheave 7 is paid out perpendicularly upward; one end thereof is wound around a first turnaround pulley 17a disposed on the top of the hoistway to suspend the passenger car 14, and the other end is wound around a second turnaround pulley 17b disposed on the top of the hoistway so as to suspend the counterweight 15. According to drive by the traction machine, the driving sheave 7 starts rotating, so that the passenger car 14 and the counterweight 15 are raised and lowered each other in a jig-back way. In the elevator described above, in order to avoid interference with the main rope 8 paid out perpendicularly upward from the driving sheave 7, the brakes 12 each of the traction machine are mounted at an angle of approximately 0° with respect to the horizontal center.
And then, in a manner similar to Embodiment 2, the preset brake gaps are set at a desired value based on the decreased amount of brake gaps owing to heat distortion, and on the relationship between the radius of the spherical section 1d and the circumferential mounting locations of the brakes 12 each (namely, the mounting locations at an angle of approximately 0° with respect to the horizontal center).
As described above, because a traction machine for an elevator in Embodiment 2 is applied to an elevator, degrees of freedom in winding-around directions for a main rope 8 are increased; thus, a variety of traction-machine locations in a hoistway can be achieved. In elevators with a variety of configurations, even when electric power is supplied to stator windings 10 for upward and downward operations, and the base 1 is heated, its heat distortion can be small, so that the decreased amount of brake gaps of brakes 12 becomes small. It is thus possible to obtain an elevator in which, it rarely occurs in a rotating state that dragging sounds are emitted due to the brake shoes 12a abutting on a brake member 6, and the brake shoes 12a wear down; and when braking, colliding sounds by the brake shoes 12a become small.

Embodiment 4.

Fig. 8 is a diagram showing another embodiment of the present invention. In the embodiment of the present invention, a construction of a rotor shaft is modified in comparison with Embodiment 1. In Fig. 8, a housing base 50 has a cylindrical section 50a, a bottom section 50b provided to close over one side of the cylindrical section 50a, and below it, a mounting section 50c to be mounted on a mounting pedestal not shown in the figure. The bottom section 50b is formed into a partially spherical section 50d; and this spherical section 50d is formed to protrude in the direction toward the other side 50e of the cylindrical section 50a. And then, the part of the spherical section 50d is formed to have a uniform thickness. The spherical section 50d has its center positioned on the axial center line outside the base 50, and is objectively formed with respect to the axial center line of the base 50. A boundary portion 50f between the cylindrical section 50a and the bottom section 50b is formed into an arc shape, and one edge of the arc shape and one edge of the spherical section 50d are formed to continuously join with each other. In the axial center of the bottom section 50b, a spindle 50g is installed upright.
On the spindle 50g, a rotor 52 is rotatably supported through bearings 51. The rotor 52 has a rotor's cylindrical section 52a opposing the cylindrical section 50a, and a rotor's boss section 5b provided on one side of the rotor's cylindrical section 52a; the rotor's boss section 5b is fixed on the bearings 51. And then, the other side of the rotor's cylindrical section 52a is opposing the bottom section 50b. The rotor 52 has a discoidal brake member 53 that is disposed adjacent to the other side 50d of the cylindrical section 50a, and is formed radially extending beyond the rotor's cylindrical section 52a. A driving sheave 54 is disposed adjacent to the brake member 53 in the order going from the cylindrical section 50a to the brake member 53, and is fastened onto the rotor 52 by bolts 55, detachable and reattachable toward the side opposite from the cylindrical section 50a. As for the rest, the same reference numerals and symbols designate the same or corresponding items in Embodiment 1. Moreover, it may also be possible to mount a bearing stand 56 on the mounting section 50c of the base 50, and to fix the bearing stand 56 at the axial end of the spindle 50g, so that the spindle 50g is supported by the base 50 and the bearing stand 56.
In the embodiment of the present invention, a traction machine for an elevator is constructed as described above, similar effects in Embodiment 1 can be obtained; in addition, because the spindle 50g is installed upright in the bottom section 50b, a component count is reduced. It is therefore possible to obtain a more economical traction machine for the elevator. Moreover, when a bearing stand 56 is provided, because a spindle 56d is supported by the base 50 and the bearing stand 56, even when the driving sheave is under heavy loads, it is possible to obtain a strong traction machine for an elevator. When the bearing stand 56 is not provided, it is possible to obtain such an elevator traction machine that is slim in the axial extent and lightweight, in which, because there is no bearing stand 56, replacing the driving sheave 54 is also easy.
By the way, in Embodiment 1, stator windings 10 are provided on the inner circumferential surface of a cylindrical section 1a. They are not limited to this, but it may be possible to consider a construction as follows: the stator windings 10 are provided on the outer circumferential surface of the cylindrical section 1a; a rotor's cylindrical section 5a is formed radially extending so as to correspondingly face the stator windings 10; field magnets 11 are mounted on the inner circumferential surface of the rotor's cylindrical section 5a, to construct a motor 11; and a brake-member surface is provided along the outer circumferential surface of the rotor's cylindrical section 5a, and corresponding to the brake-member surface, the brakes 12 are mounted on the base 1, so that the stator windings 10 as a heat generating source can be actually mounted on the base 1.
In addition, in Embodiment 1, the brakes 12 are mounted on the outer circumferential surface of the base 1. They are not limited to this, but it may be possible to consider a construction in such a manner that, a brake-member surface is provided on the inner circumferential surface of a rotor's cylindrical section 5a, and corresponding to this, brakes 12 are mounted on the bottom section 1b (the base 1) within a space formed between the bottom section 1b and the rotor 5, so that the brakes 12 can be actually mounted on the base 1.
In addition, in Embodiment 1, the brake member 6 is formed into one part together with the rotor 5, it can be however separately formed and fixed onto the rotor 5 by bolts. It is also possible to provide on the bottom section 1b an inspection hole as opposed to the gaps between the stator windings 10 and the field magnets 11. In this case, it is possible from outside to inspect accumulation of dust in the gaps between the stator windings 10 and the field magnets 11.
Moreover, in Embodiment 2, setting methods of preset brake gaps of a traction machine for an elevator in Embodiment 1 has been described; however, the methods can be similarly applied to a traction machine for an elevator in Embodiment 4.
In addition, in Embodiment 3, a traction machine for an elevator in Embodiment 2 is applied to an elevator; however, a traction machine for an elevator in Embodiment 4 can also be used.
Furthermore, in Embodiment 4, the spindle 50g is formed into one part together with the bottom section 50b; however, it is possible to fix them separately.

INDUSTRIAL APPLICABILITY

As described above, a traction machine for elevators in the present invention is suitable in use for a driving apparatus in which a main rope 8 is wound around to suspend elevator bodies, and by driving the main rope 8, the respective elevator bodies are raised and lowered.

Claims

A traction machine for an elevator, comprising:
a base(1) having a tubularly formed cylindrical section(1a), and a bottom section(1b) provided closing over one side of the cylindrical section(1a);

stator windings(10) for a motor(9), the windings(10) provided on the cylindrical section(1a);

a rotor(5) for the motor(9), the rotor(5) supported rotatably in the axial center of said base(1); and

a brake(12) disposed on said base(1), for braking said rotor(5); the traction machine characterized in that
at least one part of the bottom section(1b) is formed into a curved surface, wherein the bottom section(1b) is formed with the curved surface protruding toward said rotor(5).
The elevator traction machine as set forth in claim 1 or claim 2, wherein a boundary portion (1f) between the cylindrical section(1a) and the bottom section(1b) is formed in an arc shape, and with the base(1) being formed such that one edge of the arc shape and one edge of the curved surface are joined.
The elevator traction machine as set forth in claim 1 or claim 2, wherein a thickness of the curved surface in the bottom section(1a) is uniform.
The elevator traction machine as set forth in any one of claims 1 through 3, wherein the amount by which the curved surface protrudes toward said rotor(5) is made approximately equal to the axial width of the cylindrical section(1a).
The elevator traction machine as set forth in any one of claims 1 through 4, wherein:
the curved surface is a spherical surface centered on a single point;

the center is on the axial center line of the base(1); and

the spherical surface is objectively formed with respect to the axial center line.
The elevator traction machine as set forth in claim 5, wherein:
the brake(12) is mounted along the circumference of the base(1), and has a gap with respect to, and a brake shoe(12a) for contacting on/separating from, the rotor(5); and
based on the amount by which the gap varies owing to heat distortion by said base(1) heat-distorting under heat generated in the stator windings(10) due to current being passed through them, and on a relationship between the radius of the spherical surface and the circumferential mounting location of said brake, the gap as prior to said stator windings(10) generating heat is defined.
The elevator traction machine as set forth in any one of claims 1 through 6, further comprising a driving sheave(7) detachably/reattachably fastened onto the rotor(5).
The elevator traction machine as set forth in claim 7, wherein:
the stator windings(10) are disposed along an inner circumferential surface of the cylindrical section(1a) in the base(1);

the brake(12) is mounted on an outer circumferential surface of said base(1);

the rotor(5) has a brake member(6) corresponding to said brake(12);

the brake member(6) is disposed adjacent to the cylindrical section(1a), reversely from the bottom section(1b), and is formed discoidally, extending radially beyond the outer circumference of said rotor(5);

the driving sheave(7) is disposed adjacent to the brake member(6) in the order going from the cylindrical section(1a) to the brake member(6), wherein the driving sheave(7) is fastened onto said rotor, detachable/reattachable toward the side opposite from the cylindrical section(1a).
The elevator traction machine as set forth in any one of claims 1 through 8, wherein:
a spindle is provided upright in the axial center of the bottom section(1b), and the rotor(5) is rotatably supported on the spindle.
An elevator, comprising:
a main rope(8) wound around the driving sheave(7), an elevator body suspended by the main rope(8), and the elevator traction machine as set forth in any one of claims 1 through 9.