US2958796A - Elevators - Google Patents

Description

Nov. 1, 1960 s. SPIESS ETAL 2,953,796

ELEVATORS Filed May 3, 195s 2 Sheets-Sheet 1 1960 s. SPIESS EI'AL 2, 8,

ELEVATORS Filed May 3, 1956 2 Sheets-Sheet 2 United States Patent ELEVATORS Gustav Spiess, Geissmattstr. 21, and Karl Stutz, Hinterbramberg 6, both of Luzern, Switzerland Filed May 3, 1956, Ser. No. 582,419

4 Claims. (Cl. 310-95) This invention relates to improvements in or relating to elevators and more particularly to an operating mechanism therefor. It is an object of the invention to provide an operating mechanism for elevators which enables an elevator to be accurately stopped and which permits rapid but shock free changes of speed to be effected.

According to the invention there is provided an elevator operating mechanism comprising a coupling, the torque of which can be regulated, disposed between a driving motor and a hoist engine, and a brake whose torque can be regulated, means being provided which serve to control the torque of the coupling or the brake dependent upon the difference between an electrical magnitude corresponding to the actual speed of rotation of the hoist engine and an electrical magnitude corresponding to the nominal speed of rotation.

In order that the invention may be well understood two embodiments of apparatus according to the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a circuit diagram of one form of oper-.

ating mechanism according to the invention and Figure 2 shows a modified partial circuit diagram.

Referring to Fig. l the operating mechanism has a hoist engine 10, which is driven by a squirrel cage motor 11 via an eddy-current coupling 12 the torque transmission ratio of which can be regulated by controlling the current input. An eddy-current brake '14 provided with a tachometer dynamo 13 is coupled with the hoist engine 10, and serves to maintain the speed constant with a negative load and to maintain a definite braking action. The squirrel cage motor 11 is connected via a switch 17 to the mains 15. The pole coils 12 of the eddy-current coupling 12 are connected to a thyratron rectifier 18 via slip rings 12" and leads 16, whereas the pole coils 19 of the eddy-current brake 14 are connected to a second thyratron rectifier 20 via leads 21. The operation of the thyratrons and thus the magnitude of the exciting currents in the eddy-current coupling 12 and in the eddy-current brake 14 are controlled with opposite effects by a common amplifier 22. At the input of the amplifier 22 is applied the difference between the output voltage of a reference voltage device 23 and the voltage output of the tachometer dynamo 13 coupled with the eddy-current brake 14. The device 23 has a cathode follower tube 24, the grid 28 of which is connected with a switch 29 via a resistance 27, which can be selectively connected by switch 29 to either one of two potentiometers 30 and 31. The device 23 furthermore has resistances 32, 33 connected to the cathode of tube 24, the resistance 32 being connected with one stationary contact of a switch 34, while the other stationary contact thereof is connected with a resistance 35. 36 and 37 are condensers.

The reference voltage device 23 as described is connected with the amplifier 22 via terminals 38, 39, 40 and 41. The output terminal 42 of the device 23 is connected to the tachometer dynamo 13 as shown. This tachometerdynamo is furthermore connected with the con- 2,958,796 Patented Nov. 1, 1960 trol grid 26 of the amplifier valve 25 via an input terminal 43 of the amplifier 22.

The operation of the operating mechanism described is as follows:

For starting the operation, the motor 11 is connected to the mains 15 through the switch 17 and starts without load. Switch 29 is in a first position as shown in Fig. 1, and switch 34 is in the position also as shown. The control grid 26 of the amplifier valve 25 is, via the terminal 43, the tachometer dynamo 13 and the terminal 42, switch 34, resistance 35 of the device 23 at a negative potential, so that the valve 25 is non-conductive. As a result thereof the thyratrons in the rectifier 18 are completely out olf, those in the rectifier 20 completely conducting. The eddy-current coupling 12 is therefore not excited while the eddy-current brake 14 is fully excited.

A mechanical brake 44 is provided between the eddycurrent coupling 12 and the eddy-current brake 14 and is now released and then the switches 29 and 34 are moved upwards (as seen in Fig. 1) to their second position. The condenser 37 is charged via the resistance 27 up to the voltage available at the top of potentiometer 30. As a result the current increases in the cathode follower tube 24 and the corresponding voltage drop across the cathode resistance 33 charges via the resistor 32 the condenser 36. Now, with the rising potential thereof, the amplifier valve 25 is made conductive via the terminal 42, tachometer dynamo 13 and terminal 43, whereupon the coupling 12 is energized via amplifier 18, while the brake 14 is de-energized. The elevatorlO is started and accelerated by the coupling effect of clutch 12 according to the increase of the voltage at condenser 36. The maximum subsynchronous velocity is determined by the adjustment of potentiometer 30 since this adjustment determines the charging voltage of condenser 36.

Shortly before the intended stopping position of the elevator the switch 29 is moved downwards (as seen in Fig. 1) to its first position. Thus the condenser 37 is caused to discharge via resistance 27 to the value set on potentiometer 31. The current in the cathode follower tube 24 and with it the drop in voltage across resistance 33 become smaller, and the condenser 36 is discharged via switch 34 (in its second position) and resistance 32 to a low potential determined at 31. The potential of the control grid of the valve 25 therefore becomes more negative, so that the coupling 12 is tie-energized and the brake 14 is excited via amplifier 20. The elevator slows down to a low speed determined by the setting of the potentiometer 31. When the stopping position isreached, the switch 34 is moved downwards (as seen in Fig. 1) to its first position. The condenser 36 is recharged to a negative value via the resistance 35 with the result that the elevator is fully braked by the eddy-current brake 14. After standing still the mechanical brake 44 is applied and the motor 11 is switched off.

An alternative circuit diagram for the reference voltage device is shown in Fig. 2.

At the commencement of the operation switch 49 is moved (as seen in Fig. .2) upwards, switch 50 is closed and switch 51 opened. The previously charged condenser 52 discharges itself via resistance 53 and resistance 54, so that the control grid 48 of valve 55 becomes less negative and the valve 55 commences to conduct. The condenser 56 is charged to a value set on the potentiometer 57 via the valve 55, resistance 54 and the now closed switch 5% and switch 49 (in second position). The voltage rises at the output terminal 42 and the elevator movement accelerates in the previously described manner. The time for charging the condenser and with it the acceleration of the elevator is adjusted at the resistance 54. The voltage tapped off at potentiometer 57 corresponds to the maximum speed.

Before reaching the intended stopping position the switch 51 is closed and switch 50 opened. Thus the previously charged condenser 58 discharges via the resistances 59 and 60. The control grid of the valve 61 becomes less negative, and the condenser 56 is discharged via switch 49 in second position, the valve 61, resistance 60, switch 51 to the value set on the potentiometer 62. The speed of the discharge and therefore of the slowing down of the elevator is adjusted at the resistance 60. The elevator travels at the low speed according to the voltage set on the potentiometer 62. Upon reaching the stopping position switch 49 is moved downwards (as seen in Fig. 2). The condenser 56 is recharged to a negative value via resistance 63. The elevator comes to a standstill in the manner previously described.

The shape of the curve of the changes of speed can be influenced by the use of triodes or pentodes.

What we claim is:

1. Apparatus for electrically controlling an elevator lifting gear having a shaft carrying an electrically excitable clutch means and an electrically excitable brake means, comprising, in combination, a source of reference voltage adjustable to a desired potential value corresponding to a desired operational speed of said lifting gear, said source of reference voltage comprising a circuit having input terminals for being supplied with DC. voltage, and output terminals for delivering predetermined reference voltages, electron tube means having an anode, a cathode and a control grid, voltage divider means connected to said input terminals for deriving from said D.C. input voltage predetermined operating voltages to be applied to said control grid, a first capacitive circuit including first capacitor means in series with first variable resistor means in circuit with said voltage divider means and with said control grid in such a manner that said first capacitor means may be charged to predetermined potentials and that these predetermined potentials are applied as bias potentials to said control grid, a cathode resistor connected to said cathode, a second capacitive circuit including second capacitor means in series with second variable resistor means in circuit with said cathode resistor for charging said second capacitor means with a charging potential corresponding to the voltage drop across said cathode resistor depending upon said bias potentials applied to said control grid, the terminals of said second capacitor means being connected to said output terminals for delivering said charging potential as reference voltage depending upon the setting of said voltage divider means and the setting of said variable resistor means; a speed-responsive voltage source providing a potential value corresponding to the operational speed of said lifting gear at any given moment; and amplifier means, in circuit with said electrically excitable clutch and brake means, respectively, and connected to said two voltage sources, for controlling the excitation of said clutch and brake means, respectlvely, depending upon the difference between said two potential values.

2. Apparatus for electrically controlling an elevator lifting gear having a shaft carrying an electrically excitable clutch means and an electrically excitable brake means, comprising, in combination, a source of reference voltage adjustable to a desired potential value corresponding to a desired operational speed of said lifting gear, said source of reference voltage comprising a circuit having a first and a second input terminal for being supplied with DC. voltage, and at least one first and one second output terminal, a first lead connecting said first input and output terminals with each other, a second lead connecting said second input and output terminals with each other, a cathode follower tube having an anode, a control grid and a cathode, a cathode resistor connected between said cathode and said second lead, said anode being connected with said first lead,'a series-combination of, at least two otentiometers @9 nected as voltage dividers between said input terminals, first capacitor means and a first variable resistor means connected in series with said first capacitor means for predetermining a charging potential of the latter, a junction point between said first variable resistor means and said first capacitor means being connected with said control grid, and the opposite end of said capacitor means being connected to said second lead, switch means connected between the free end of said first variable resistor means and the slidable tap contacts of said potentiometers and movable between two alternative positions in such a manner that alternatively either one of the adjusted potentials available at said tap contacts may be applied to said free end of said first variable resistor for charging said first capacitor means and for correspondingly applying said charging potential to said control grid, a second variable resistor connected to a junction point between said cathode and said cathode resistor, second capacitor means connected at one end with said second output terminal, the free end of said second variable resistor being connected with said second capacitor means for applying to the latter a charging potential depending upon the setting of said second variable resistor and upon the voltage drop across said cathode resistor determined by the tube current which in turn depends upon the predetermined charging potential of said first capacitor means as applied to said control grid; a speed-responsive voltage source providing a potential value corresponding to the operational speed of said lifting gear at any given moment and connected in series with the other end of said second capacitor means; and amplifier means, in circuit with said electrically excitable clutch and brake means, respectively, and connected to the series-combination formed by said speed responsive voltage source and said second capacitor means, for controlling the excitation of said clutch and brake means, respectively, depending upon the difference between said two potential values.

3. In an arrangement for controlling an elevator lifting gear, in combination, a source of reference voltage adjustable to a desired potential value corresponding to a desired operational speed of said lifting gear, said source of reference voltage comprising a circuit having input terminals for being supplied with DC voltage, electron tube means having an anode, a cathode and a control grid, voltage divider means connected to said input terminals for deriving from said D.C. input voltage predetermined operating voltages to be applied to said control grid, a first capacitive circuit including a series-combination of first capacitor means and first variable resistor means in circuit with said voltage divider means and with said control grid in such a manner that said first capacitor means may be charged to predetermined potentials and that these predetermined potentials are applied as bias potentials to said control grid, a cathode resistor connected to said cathode, a second capacitive circuit including a seriescombination of second capacitor means and second variable resistor means in circuit with said cathode resistor for charging said second capacitor means with a charging potential corresponding to the voltage drop across said cathode resistor depending upon said bias potentials applied to said control grid, the terminals of said second capacitor means serving as output terminals for delivering said charging potential as a predetermined reference voltage depending upon the setting of said voltage divider means and thesetting of said variable resistor means.

4. In an arrangement for controlling an elevator lifting gear, in combination, a source of reference voltage adjustable to a desired potential value corresponding to a desired operational speed of said lifting gear, said source of reference voltage comprising a circuit having a firs-t and a second input terminal for being supplied with DC voltage, a first lead connected to said first input terminal,

a second lead connected to said second input terminal, a cathode follower tube having an anode, a control grid and a cathode, a cathode resistor connected between said cathode and said second lead, said anode being connected with said first lead, a series-combination of at least two otentiometers connected as voltage dividers between said input terminals, first capacitor means and a first variable resistor connected in series with said first capacitor means for predetermining a charging potential of the latter, a junction point between said first variable resistor and said first capacitor means being connected with said control grid, and the opposite end of said capacitor means being connected to said second lead, switch means connected between the free end of said first variable resistor and the slidable tap contacts of said potentiometers and movable between two alternative positions in such a manner that alternatively either one of the adjusted potentials available at said tap contacts may be applied to said free end of said first variable resistor for charging said first capacitor means and for correspondingly applying said charging potential to said control grid, a second variable resistor connected to a junction point between said cathode and said cathode resistor, second capacitor means having one of its terminals connected with said second lead,

the free end of said second variable resistor being connected with the other terminal of said second capacitor means for applying to the latter a charging potential depending upon the setting of said second variable resistor and upon the voltage drop across said cathode resistor determined by the tube current which in turn depends upon the predetermined charging potential of said first capacitor means as applied to said control grid, said terminals of said second capacitor means serving as output terminals for delivering the charging potential of said second capacitor means as a predetermined reference voltage depending upon the setting of said potentiometers and of said variable resistors.

References Cited in the file of this patent UNlTED STATES PATENTS 2,411,122 Winther Nov. 12, 1946 2,541,182 Winther Feb. 13, 1951 2,551,021 Lee May 1, 1951 2,551,839 Jaeschke May 8, 1951 2,714,917 Siegerist Aug. 9, 1955

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