EP2383216A1

EP2383216A1 - Elevator device

Info

Publication number: EP2383216A1
Application number: EP09839159A
Authority: EP
Inventors: Mineo Okada
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2009-01-28
Filing date: 2009-01-28
Publication date: 2011-11-02
Also published as: WO2010086967A1; CN102239100A; JPWO2010086967A1; KR20110094139A

Abstract

In an elevator apparatus, a car is moved inside a hoistway. A speed governor includes: a rotating shaft that rotates in response to movement of the car; a centrifugal weight that revolves around the rotating shaft together with the rotation of the rotating shaft; an extensible arm that links the centrifugal weight to the rotating shaft, and that is displaced relative to the rotating shaft in response to a centrifugal force to which the centrifugal weight is subjected due to the revolution; and a displacement setting apparatus that extends and retracts the extensible arm to set a length of the extensible arm to different lengths during normal rotation and during reverse rotation of the rotating shaft. The speed governor detects presence or absence of an abnormality in a speed of the car based on the displacement of the extensible arm relative to the rotating shaft.

Description

TECHNICAL FIELD

The present invention relates to an elevator apparatus that has a car that is moved inside a hoistway.

BACKGROUND ART

Conventionally, elevator apparatuses are known that operate a speed governor to make a car perform an emergency stop if a car speed exceeds a predetermined set overspeed. Generally, the set overspeed at which the speed governor operates is equal whether the direction of movement of the car is an ascending direction or a descending direction.
However, for example, if pit depth in the hoistway is limited, there is demand to make a set overspeed in the speed governor during descent of the car lower than during ascent because of allowable car speeds in buffers that are installed in the pit.
Conventionally, in order to make the set overspeed during descent of the car lower than during ascent, speed governors have been proposed in which mechanical power transmission between two speed controlling mechanisms is connected and released by a clutch apparatus. The set overspeed of the first speed controlling mechanism is higher than the set overspeed of the second speed controlling mechanism. During ascent of the car, the respective speed controlling mechanisms are disconnected from each other by the clutch apparatus, and only the first speed controlling mechanism that has the higher set overspeed functions. During descent of the car, the speed controlling mechanisms are connected by means of the clutch apparatus, and both of the speed controlling mechanisms function. Thus, the set overspeed of the speed governor is lower during descent of the car than during ascent (See Patent Literature 1).

[Patent Literature 1]

Japanese Patent Laid-Open No. 2000-327241 (Gazette)

DISCLOSURE OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

However, because two speed controlling mechanisms are required in conventional elevator apparatuses such as that described above, the number of parts is increased, increasing costs. Overall dimensions of the speed governor are also increased, preventing size reductions in the elevator apparatus.
The present invention aims to solve the above problems and an object of the present invention is to provide an elevator apparatus that enables a set overspeed of a speed governor to be different during ascent and during descent of a car, that enables cost reductions to be achieved, and that also enables size reductions to be achieved.

MEANS FOR SOLVING THE PROBLEM

In order to achieve the above object, according to one aspect of the present invention, there is provided an elevator apparatus characterized in including: a car that can be moved inside a hoistway; and a speed governor including: a rotating shaft that rotates in response to movement of the car; a centrifugal weight that revolves around the rotating shaft together with the rotation of the rotating shaft; an extensible arm that links the centrifugal weight to the rotating shaft, and that is displaced relative to the rotating shaft in response to a centrifugal force to which the centrifugal weight is subjected due to the revolution; and a displacement setting apparatus that extends and retracts the extensible arm to set a length of the extensible arm to different lengths during normal rotation and during reverse rotation of the rotating shaft, the speed governor detecting presence or absence of an abnormality in a speed of the car based on the displacement of the extensible arm relative to the rotating shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a structural diagram that shows an elevator apparatus according to Embodiment 1 of the present invention;
Figure 2 is a longitudinal cross section that shows a speed governor from Figure 1;
Figure 3 is a longitudinal cross section that shows a state in which extensible arms of the speed governor from Figure 2 are extended; and
Figure 4 is a front elevation that shows the speed governor from Figure 2.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the present invention will now be explained with reference to the drawings.

Embodiment 1

Figure 1 is a structural diagram that shows an elevator apparatus according to Embodiment 1 of the present invention. In the figure, a machine room 2 is disposed in an upper portion of a hoistway 1. Disposed inside the machine room 2 are: a hoisting machine (a driving machine) 4 that has a driving sheave 3; a deflecting sheave 5 that is disposed so as to be positioned at a distance from the driving sheave 3; and a controlling apparatus 6 that controls elevator operation.
A common main rope 7 is wound around the drive sheave 3 and the deflecting sheave 5. A car 8 and a counterweight 9 that can be raised and lowered inside the hoistway 1 are suspended by the main rope 7. The car 8 and the counterweight 9 are raised and lowered inside the hoistway 1 by rotation of the drive sheave 3. When the car 8 and the counterweight 9 are raised and lowered inside the hoistway 1, the car 8 is guided by car guide rails (not shown), and the counterweight 9 is guided by counterweight guide rails (not shown).
An emergency stopper apparatus 10 that stops falling of the car 8 is disposed on a lower portion of the car 8. An operating arm 11 is disposed on the emergency stopper apparatus 10. The emergency stopper apparatus 10 grips the car guide rails on operation of the operating arm 11. Movement of the car 8 is stopped by gripping of the car guide rails by the emergency stopper apparatus 10.
A speed governor 12 is disposed inside the machine room 2, and a tensioning sheave 13 is disposed in a lower portion inside the hoistway 1. The speed governor 12 has: a speed governor main body 14; and a speed governor sheave 15 that is disposed on the speed governor main body 14. A speed governor rope 16 is wound around the speed governor sheave 15 and the tensioning sheave 13. A first end portion and a second end portion of the speed governor rope 16 are connected to the operating arm 11. The speed governor sheave 15 and the tensioning sheave 13 are thereby rotated in response to movement of the car 8. The speed governor sheave 15 and the tensioning sheave 13 are rotated normally by ascent of the car 8, and are rotated in reverse by descent of the car 8.
The speed governor main body 14 grips the speed governor rope 16 if rotational speed of the speed governor sheave 15 reaches a predetermined set overspeed. The operating arm 11 is operated by the speed governor rope 16 being gripped by the speed governor main body 14 and the car 8 being displaced relative to the speed governor rope 16.
A car buffer 17 that is positioned below the car 8, and a counterweight buffer 18 that is positioned below the counterweight 9 are disposed in a bottom portion (a pit) of the hoistway 1. When subjected to a collision with the car 8, the car buffer 17 relieves mechanical shock that is imparted to the car 8. When subjected to a collision with the counterweight 9, the counterweight buffer 18 relieves mechanical shock that is imparted to the counterweight 9.
Figure 2 is a longitudinal cross section that shows the speed governor 12 from Figure 1. Figure 3 is a longitudinal cross section that shows a state in which extensible arms of the speed governor 12 from Figure 2 are extended. In addition, Figure 4 is a front elevation that shows the speed governor 12 from Figure 2. In the figure, the speed governor 12 is supported by a supporting body 19. The speed governor main body 14 has: a sheave interlocking device 20 that operates interdependently with the speed governor sheave 15 in response to rotational speed of the speed governor sheave 15; an overspeed detecting switch 21 that outputs a stopping signal that stops elevator operation on being activated by the sheave interlocking device 20; and a gripping apparatus 22 that grips the speed governor rope 16 on being activated by the sheave interlocking device 20 (Figure 4).
As shown in Figures 2 and 3, a sheave shaft 23 of the speed governor sheave 15 is supported horizontally in the supporting body 19 by means of bearings 24. A driving bevel gear 25 is fixed to an end portion of the sheave shaft 23.
The sheave interlocking device 20 has: a driven shaft (a rotating shaft) 26 that is disposed so as to be parallel to a vertical direction; a driven bevel gear 27 that is fixed to a lower end portion of the driven shaft 26, and that intermeshes with the driving bevel gear 25; a displacing body 28 that is disposed on the driven shaft 26, and that is displaceable relative to the driven shaft 26 in a direction that is parallel to the driven shaft 26; a centrifugally displacing apparatus 29 that displaces the displacing body 28 in response to the rotation of the driven shaft 26; and a displacement setting apparatus 30 that can set the centrifugally displacing apparatus 29 such that a relationship between the rotational speed of the driven shaft 26 and displacement of the displacing body 28 is different during normal rotation and during reverse rotation of the driven shaft 26.
The driven shaft 26 is supported by the supporting body 19 so as to have a bearing 31 interposed. The rotation of the sheave shaft 23 is transmitted to the driven shaft 26 by means of the driving bevel gear 25 and the driven bevel gear 27. Consequently, the driven shaft 26 is rotated in response to the rotation of the speed governor sheave 15. Specifically, the driven shaft 26 is rotated normally during normal rotation of the speed governor sheave 15, and is rotated in reverse during reverse rotation of the speed governor sheave 15.
The centrifugally displacing apparatus 29 is disposed on an upper portion of the driven shaft 26. The centrifugally displacing apparatus 29 is rotated together with the driven shaft 26. In addition, the centrifugally displacing apparatus 29 has: a pair of fly balls (centrifugal weights) 32 that revolve around the driven shaft 26 together with the rotation of the driven shaft 26; a pair of extensible arms 33 that respectively link each of the fly balls 32 to an upper end portion of the driven shaft 26, and that can pivot relative to the driven shaft 26; a sliding cylinder 34 that is passed slidably over the driven shaft 26; linking members 35 that link the respective extensible arms 33 and the sliding cylinder 34; and a balancing spring 36 that forces the sliding cylinder 34 downward.
The fly balls 32 are subjected to centrifugal forces that correspond to the rotational speed of the driven shaft 26 by revolving around the driven shaft 26.
The extensible arms 33 are displaced by pivoting relative to the driven shaft 26 in response to the centrifugal forces to which the fly balls 32 are subjected. The sliding cylinder 34 is displaced in a direction that is parallel to the driven shaft 26 in response to the displacement of the respective extensible arms 33 relative to the driven shaft 26. Specifically, when the rotational speed of the driven shaft 26 increases, the extensible arms 33 are displaced in a direction in which the fly balls 32 move away from each other, and the sliding cylinder 34 is displaced upward in opposition to force from the balancing spring 36. When the rotational speed of the driven shaft 26 decreases, the extensible arms 33 are displaced in a direction in which the fly balls 32 move toward each other, and the sliding cylinder 34 is displaced downward by the force from the balancing spring 36.
The extensible arms 33 each have: an arm main body 37 that is mounted so as to be able to pivot relative to the driven shaft 26; and an actuator 38 that is disposed on the arm main body 37, and that changes the length of the extensible arm 33.
The actuators 38 have: plungers 39 that are displaceable relative to the arm main bodies 37; and electromagnetic coils 40 that displace the plungers 39 relative to the arm main bodies 37.
The fly balls 32 are mounted to the plungers 39. The plungers are displaceable between an extended position (Figure 3) that is away from the arm main body 37; and a retracted position (Figure 2) that is closer to the arm main body 37 than the extended position. Length of the extensible arms 33 is changed by the plungers 39 being displaced between the extended position and the retracted position. The plungers are displaced to the extended position by passing electric current to the electromagnetic coils 40, and are displaced to the retracted position by forces from forcing bodies (not shown) when the passage of electric current to the electromagnetic coils 40 is stopped.
The displacing body 28 is displaceable together with the sliding cylinder 34. The displacing body 28 is thereby displaced in a direction that is parallel to the driven shaft 26 in response to the rotational speed of the speed governor sheave 15. The displacing body 28 is also rotatable relative to the sliding cylinder 34 and the driven shaft 26. Consequently, the displacing body 28 is not rotated even if the sliding cylinder 34 and the driven shaft 26 are rotated. In addition, the displacing body 28 has: a driven tube 41 that is passed slidably over the driven shaft 26; and an operating portion 42 that protrudes outward from an outer circumferential surface of the driven tube 41.
The displacement setting apparatus 30 extends and retracts the respective extensible arms 33 to set the length of the respective extensible arms 33 to different lengths during normal rotation and during reverse rotation of the driven shaft 26. Specifically, the displacement setting apparatus 30 makes the relationship between the rotational speed of the driven shaft 26 and displacement of the displacing body 28 different during normal rotation and during reverse rotation of the driven shaft 26 by making the orbital radius of the fly balls 32 different during normal rotation and during reverse rotation of the driven shaft 26.
In this example, the displacement setting apparatus 30 shortens the length of the extensible arms 33 during normal rotation of the driven shaft 26 (i.e., during ascent of the car 8), and makes the length of the extensible arms 33 longer than during normal rotation of the driven shaft 26 during reverse rotation of the driven shaft 26 (i.e., during descent of the car 8).
The displacement setting apparatus 30 has: a generator 43 that generates electric power from the rotation of the driven shaft 26; and a rectifying apparatus 44 that sends electric power to the electromagnetic coils 40 from the electric power that is generated by the generator 43 either only during normal rotation or only during reverse rotation of the driven shaft 26.
The generator 43 is disposed on an upper end portion of the driven shaft 26. The generator 43 is assumed to be a direct-current generator. In addition, the generator 43 has: a generator fixed shaft 45 that includes permanent magnets; and a generator main body 46 that includes a power generating coil, and that surrounds the generator fixed shaft 45. The generator fixed shaft 45 is mounted to the supporting body 19 by means of a mounting bracket 47. The generator main body 46 is rotated together with the driven shaft 26. Electric current flows through the power generating coil when the generator main body 46 is rotated together with the driven shaft 26. Direction of the electric current that flows through the power generating coil changes depending on the direction of rotation of the driven shaft 26. Specifically, the generator 43 generates a positive electric current during normal rotation of the driven shaft 26, and generates a negative electric current during reverse rotation of the driven shaft 26.
The rectifying apparatus 44 is electrically connected to the generator main body 46 and the electromagnetic coils 40, respectively, by conducting wires 48 and 49. The rectifying apparatus 44 sends either only the positive or only the negative electric current from the generator 43 to the electromagnetic coils 40. The electric power is thereby sent to the electromagnetic coils 40 from the rectifying apparatus 44 either only during normal rotation of the driven shaft 26 or only during reverse rotation.
In this example, only the negative electric current of the positive and negative electric current from the generator 43 (i.e., only the electric current during descent of the car 8) is sent from the rectifying apparatus 44 to the electromagnetic coils 40. The positive electric current is shut off by the rectifying apparatus 44, and does not reach the electromagnetic coils 40. Consequently, the length of the extensible arms 33 is extended during descent of the car 8, and the length of the extensible arms 33 is shortened during ascent of the car 8.
The overspeed detecting switch 21 is disposed radially outside the driven tube 41. The overspeed detecting switch 21 has: a switch main body 50 that is fixed to the supporting body 19; and a switch lever 51 that is disposed on the switch main body 50, and that projects toward the displacing body 28. The operating portion 42 is able to operate the switch lever 51 by displacement of the displacing body 28 relative to the overspeed detecting switch 21. The overspeed detecting switch 21 detects abnormality in the speed of the car 8 by the switch lever 51 being operated by the operating portion 42. Specifically, the overspeed detecting switch 21 detects the presence or absence of an abnormality in the speed of the car 8 based on the presence or absence of detection of the displacing body 28. A stopping signal that stops elevator operation is output from the switch main body 50 on detection of an abnormality in the speed of the car 8 by the overspeed detecting switch 21.
Because the orbital radius of the fly balls 32 increases when the length of the extensible arms 33 is long, the displacement of the displacing body 28 is greater than when the length of the extensible arms 33 is short. Consequently, when the length of the extensible arms 33 is long, the displacing body 28 will reach the position at which the switch lever 51 is operated at a stage when the rotational speed of the driven shaft 26 is lower than when the length of the extensible arms 33 is short. In other words, the rotational speed of the driven shaft 26 at which the overspeed detecting switch 21 detects abnormality in the speed of the car 8 (first preset overspeed) is a value that is lower when the length of the extensible arms 33 is long (during descent of the car 8) than when the length of the extensible arms 33 is short (during ascent of the car 8).
The controlling apparatus 6 controls elevator operation based on information from the overspeed detecting switch 21. In this example, upon receiving the stopping signal from the overspeed detecting switch 21, the controlling apparatus 6 determines that an abnormality has arisen in the speed of the car 8, and performs control that stops elevator operation.
The gripping apparatus 22 is disposed below the speed governor sheave 15 as shown in Figure 4. The gripping apparatus 22 has: a fixed shoe 52 that is fixed to the supporting body 19; a movable shoe 53 that is displaceable between a gripping position that grips the speed governor rope 16 against the fixed shoe 52 and an open position that is further away from the fixed shoe 52 than the gripping position; a displacing pressing apparatus 54 that generates a gripping force that grips the speed governor rope 16 between the movable shoe 53 that has been displaced to the gripping position and the fixed shoe 52; and a holding apparatus 55 that holds the movable shoe 53 in the open position during normal operation, and that releases holding of the movable shoe 53 when the rotational speed of the driven shaft 26 reaches a second preset overspeed that is higher than the first preset overspeed.
The displacing pressing apparatus 54 has: a shoe compressible arm 56 that is connected between the mount portion that is disposed on the supporting body 19 and the movable shoe 53, and that can be extended and retracted; and a compressed spring (a forcing body) 57 that is disposed on the shoe compressible arm 56, and that forces the movable shoe 53 away from the mount portion of the supporting body 19.
The shoe compressible arm 56 is pivotably connected to both the mount portion of the supporting body 19 and the movable shoe 53. The movable shoe 53 is displaced between the gripping position and the open position by the shoe compressible arm 56 being pivoted relative to the mount portion of the supporting body 19. The shoe compressible arm 56 is pushed against the fixed shoe 52 and compressed when the movable shoe 53 is displaced to the gripping position. The shoe compressible arm 56 is subjected to the force of the compressed spring 57 and extended when the movable shoe 53 is displaced to the open position.
The compressed spring 57 is compressed between the mount portion of the supporting body 19 and the movable shoe 53. The compressed spring 57 is assumed to be a coil spring through which the shoe compressible arm 56 has been passed internally. The force from the compressed spring 57 increases as the shoe compressible arm 56 is compressed.
A gripping force from the displacing pressing apparatus 54 arises due to the movable shoe 53 being displaced toward the gripping position and the force from the compressed spring 57 increasing.
The holding apparatus 55 has: an engaging lever 58 that is displaceable between an engaged position that engages with the movable shoe 53 and a released position in which engagement with the movable shoe 53 is disengaged; a releasing spring (a forcing body) 59 that forces the engaging lever 58 in such a direction as to be displaced toward the released position; and a restraining member 60 that holds the engaging lever 58 in the engaged position in opposition to the force from the releasing spring 59.
The engaging lever 58 is displaced between the engaged position and the released position by being pivoted around a lever shaft 61 that is disposed on the supporting body 19. The releasing spring 59 is connected between the engaging lever 58 and the supporting body 19.
The restraining member 60 is pivotable around a supporting shaft 62 that is disposed on the supporting body 19. The restraining member 60 is linked to the displacing body 28 by means of a link 63. The restraining member 60 is thereby pivoted around the supporting shaft 62 in response to the displacement of the displacing body 28.
The link 63 is pivotably connected to both the displacing body 28 and the restraining member 60. The link 63 is displaced upward by an increase in the rotational speed of the driven shaft 26.
The engaging lever 58 is held in the engaged position by the restraining member 60 during normal operation. The restraining member 60 is pivoted by upward displacement of the link 63 in a direction in which holding of the engaging lever 58 by the restraining member 60 is disengaged. Holding of the engaging lever 58 by the restraining member 60 is disengaged when the rotational speed of the driven shaft 26 exceeds the first preset overspeed and reaches the second set overspeed.
When holding of the engaging lever 58 by the restraining member 60 is disengaged, the engaging lever 58 is displaced from the engaged position to the released position by the force of the releasing spring 59, and disengaging engagement between the movable shoe 53 and the engaging lever 58. When engagement between the movable shoe 53 and the engaging lever 58 is disengaged, the movable shoe 53 is displaced to the gripping position under its own weight, and the speed governor rope 16 is gripped between the fixed shoe 52 and the movable shoe 53.
Next, operation will be explained. When the car 8 is moved, the driven shaft 26 is rotated in response to the movement of the car 8, and the displacing body 28 is displaced parallel to the driven shaft 26 in response to the rotational speed of the driven shaft 26. if the car 8 is moved at normal operating speeds, displacement of the displacing body 28 is small, and the switch lever 51 is not operated by the operating portion 42.
If the speed of the car 8 increases and reaches the first set overspeed for some reason, the switch lever 51 is operated by the operating portion 42. A stopping signal is thereby sent to the controlling apparatus 6 from the overspeed detecting switch 21. When the controlling apparatus 6 receives the stopping signal, elevator operation is stopped forcibly by control from the controlling apparatus 6.
If the speed of the car 8 subsequently increases further and reaches the second set overspeed despite shutdown control being performed by the controlling apparatus 6, holding of the engaging lever 58 by the restraining member 60 is disengaged, and the speed governor rope 16 is gripped between the fixed shoe 52 and the movable shoe 53. Thus, movement of the speed governor rope 16 stops, and the car 8 is moved relative to the speed governor rope 16.
When the car 8 is moved relative to the speed governor rope 16, the operating arm 11 is operated, and an operation that grips the car guide rails is performed by the emergency stopper apparatus 10. A braking force is thereby applied directly to the car 8.
Next, operation of the sheave interlocking device 20 will be explained. When the car 8 ascends, the driven shaft 26 is rotated normally. Positive electric current is thereby generated by the generator 43. The positive electric current from the generator 43 is shut off by the rectifying apparatus 44, and is not sent to the electromagnetic coils 40. The plungers 39 are thereby displaced to the retracted position, and the extensible arms 33 retract. In other words, when the car 8 ascends, the fly balls 32 are orbited around the driven shaft 26 with the extensible arms 33 in a retracted state.
When the car 8 descends, the driven shaft 26 is rotated in reverse. Negative electric current is thereby generated by the generator 43. The negative electric current from the generator 43 passes through the rectifying apparatus 44 and is sent to the electromagnetic coils 40. The plungers 39 are thereby displaced to the extended position, and the extensible arms 33 extend. In other words, when the car 8 is descends, the fly balls 32 are orbited around the driven shaft 26 with the extensible arms 33 in an extended state.
Because the orbital radius of the fly balls 32 is greater during descent of the car 8 than during ascent, the respective rotational speeds of the driven shaft 26 for displacing the displacing body 28 to the position at which the switch lever 51 is operated, and to the position at which the restraining member 60 is displaced to the released position, are lower during descent of the car 8 than during ascent. In other words, the first and second preset overspeeds are lower during descent of the car 8 than during ascent.
In an elevator apparatus of this kind, because a displacement setting apparatus 30 is disposed in which extensible arms 33 that link fly balls 32 of a speed governor 12 to a driven shaft 26 are able to extend and retract, and the length of the extensible arms 33 is set to different lengths during normal rotation and during reverse rotation, the orbital radius of the fly balls 32 can be set so as to be different during ascent and during descent of the car 8. First and second preset overspeeds for detecting abnormality in the speed of the car 8 can thereby be made different during ascent and during descent of the car 8. Because it is no longer necessary to dispose two speed controlling mechanisms for which the preset overspeeds are set separately, the number of parts can be reduced, enabling cost reductions. In addition, because overall reductions in the size of the speed governor 12 can also be achieved, size reductions can also be achieved in the elevator apparatus.
Because the displacement setting apparatus 30 has: a generator 43 that generates electric power from the rotation of the driven shaft 26; and a rectifying apparatus 44 that sends electric power to the electromagnetic coils 40 of the extensible arms 33 from the electric power that is generated by the generator 43 either only during normal rotation or only during reverse rotation of the driven shaft 26, external supply of power can be eliminated, enabling the speed governor 12 to be operated in response to the direction of movement of the car 8 more reliably.
Adjustment of the first and second preset overspeeds during both ascent and descent of the car 8 can also be easily performed simply by adjusting the retracted positions and the extended positions of the plungers 39.
Moreover, in the above example, the rectifying apparatus 44 sends only negative electric current to the electromagnetic coils 40, but a rectifying apparatus that sends only positive electric current to the electromagnetic coils 40 may also be used. The first and second preset overspeeds of the car 8 during descent can thereby be set so as to be higher than the first and second preset overspeeds of the car 8 during ascent.

Claims

An elevator apparatus characterized in comprising:
a car that can be moved inside a hoistway; and

a speed governor comprising:
a rotating shaft that rotates in response to movement of the car;

a centrifugal weight that revolves around the rotating shaft together with the rotation of the rotating shaft;

an extensible arm that links the centrifugal weight to the rotating shaft, and that is displaced relative to the rotating shaft in response to a centrifugal force to which the centrifugal weight is subjected due to the revolution; and

a displacement setting apparatus that extends and retracts the extensible arm to set a length of the extensible arm to different lengths during normal rotation and during reverse rotation of the rotating shaft,

the speed governor detecting presence or absence of an abnormality in a speed of the car based on the displacement of the extensible arm relative to the rotating shaft.
An elevator apparatus according to Claim 1, characterized in that:
the extensible arm comprises an electromagnetic coil that changes the length of the extensible arm on receiving electric power; and

the displacement setting apparatus comprises:
a generator that generates electric power from the rotation of the rotating shaft; and

a rectifying apparatus that sends electric power to the electromagnetic coil from the electric power that is generated by the generator either only during normal rotation or only during reverse rotation of the rotating shaft.