US3298464A

US3298464A - Elevator control circuit

Info

Publication number: US3298464A
Application number: US307451A
Authority: US
Inventors: Robert D Sturm
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-09-09
Filing date: 1963-09-09
Publication date: 1967-01-17
Anticipated expiration: 1984-01-17

Description

Jan. 17, 1967 R. D. STURM 3,298,464

ELEVATOR CONTROL CIRCUIT Filed Sept. 9, 1963 ROBERT 0. STURM INVE N TOR BY BUG/(HORN BLORE K L APQU/$T& SPAR/(MAN ATTORNEYS United States Patent 3,298,464 ELEVATOR CONTROL CIRCUIT Robert D. Sturm, 1720 NE. 36th Ave., Portland, Oreg. 97212 Filed Sept. 9, 1963, Ser. No. 307,451 8 Claims. (Cl. 18729) The subject matter of the present invention relates generally to control systems for automatic elevators, and in particular to selective collective type automatic elevator control circuits which move the elevator car to answer up calls only when the car is traveling in the up direction and to answer down calls only when such car is moving in a down direction.

The elevator control circuit of the present invention is especially useful when employed with automatic push button elevators which do not require an attendant and are operated by the passengers of such elevator. The present selective collective type elevator control circuit has several advantages over conventional elevator control circuits of this type, including a simpler, safer and more reliable operation. In addition, the control circuit of the present invention has fewer components and is less expensive than previous control circuits of this type. Furthermore, the present elevator control system moves the elevator car in a smooth, quiet, and efficient manner.

It is therefore one object of the present invention to provide an improved elevator control circuit for operation of the elevator in a smooth, quiet and safe manner.

Another object of the invention is to provide an improved selective collective type automatic elevator control circuit which is simpler and less expensive.

A further object of the present invention is to provide an automatic control circuit for an elevator which operates in a fast, efficient and reliable manner.

An additional object of the invention is to provide an improved selective collective type elevator control circuit having fewer components.

Other objects and advantages in the present invention will be apparent from the following detailed description of a preferred embodiment thereof and from the attached drawings, of which:

The figure is a schematic diagram of one embodiment of the elevator control circuit of the present invention.

As shown in the figure, one embodiment of a selective collective type automatic control circuit in accordance with the present invention includes a main up relay 10* having five pairs of normally open fixed contacts and two pairs of normally closed fixed contacts. One contact of each of the first three pairs of contacts is connected to a different one of three high

voltage power lines

12, 14 and 16, respectively, and the other contact of such pairs of contacts is connected to a different one of the terminals of an electric motor 18 which functions to raise the elevator car. The second power line 14 is connected through a fuse 20 to one terminal of the filed winding for the solenoid which changes the position of the movable contacts of the main up relay. The other terminal of this solenoid winding is connected through one of the normally closed contacts of a main down relay 3% and an auxiliary down re-1ay22 to actuate the main up relay in a manner hereafter described. Thus, actuation of the main up relay 10 closes the contacts connected between power lines and the motor 18 so that such motor is energized and causes the elevator to move up until the main up relay is deactuated.

While the same or a second electric motor may be provided for lowering the elevator car, this can be accomplished by means of a hydraulic system (not shown) which is controlled by an electric-magnetic valve 24 having one terminal connected to the second power line 14 through a lead 26 and the other terminal of such valve connected through one of the normally closed contacts of the main up relay 10 and an auxiliary up relay 28 to actuate such valve in a manner hereafter described. This causes liquid to flow out of a main cylinder (not shown) in the hydraulic system and allows the car to be lowered by gravity smoothly and safely. The other terminal of the valve 24 is also connected to one terminal of the solenoid winding of the main down relay 30 which has the other terminal of such winding connected to the second power line 14 through lead 26. It should be noted that one terminal of the solenoid windings of all relays and the valve 24 is connected directly to such second power line 14.

The first pair of contacts at the left end of the main down relay 30 are normally closed and are connected to the first power line 12 through a lead 31, a sixth pair of normally closed contacts of the main up relay and a fuse 32. The first pair of contacts on the main down relay is also connected to one of a pair of normally open contacts on a first time delay relay 34 which does not turn off from its actuated position to the normal position shown after a time delay of about /2 second later than when such relay is deenergized for a reason hereafter discussed. The normally open second pair of contacts of the main down relay 30 is connected between the first power line 12 and the normally closed second pair of contacts on the auxiliary up relay 28 to one terminal of the solenoid winding of the auxiliary down relay 22 in order to actuate such auxiliary down relay in response to actuation of the main down relay and the valve 24. The second normally open third pair of contacts on the main down relay 30 and the normally open fifth pair of contacts on the main up relay 10 are both connected between a common lead 36 and the first power line 12 through lead 38. The common lead 36 is connected to one terminal of the solenoid winding of the first time delay relay 34 whose other winding terminal is connected to the second power line 14 through lead 39. Thus, the first time delay relay is energized when either the main up relay or the main down relay is actuated.

The normally closed contacts of the first time delay relay 34 are connected to the first power line 12 through a common lead 40, and the normally closed contacts of another time delay relay 42. Such normally closed contact of relay 34 are also connected to one of the normally open third pair of contacts on both the auxiliary up relay 28 and the auxiliary down relay 22. The other contact of both of such third pair of contacts is connected to the solenoid windings of the auxiliary relays so that when either of these auxiliary relays is actuated it is held in an energized position by current fiow from the first power line through the third pairs of contacts to the windings of such auxiliary relays.

Throughout the description of the control circuit of the present invention, the order of the pairs of relay contacts will be referring to the position such contacts are located with respect to the left side of the relays. Insofar as the main up relay is concerned, the lower three pairs of contacts are numbered consecutively from the left side of such relay as fifth, sixth and seventh pairs of contacts.

One of the normally open pair of contacts of the first time delay relay 34 is connected to the solenoid winding of a second time delay relay 44 which also delays before turning off after it is deenergized. The time delay of first relay 34 causes its normally open pair of contacts to remain closed after the main down relay 30 or the main up relay 10 have been deenergized to deenergize such first relay, for a sufiicient time so that current flows through the solenoid winding of the second time delay relay 44 from the first power line by way of the normally closed first pair of contacts of the relay 30 and sixth pair of contacts of relay 10. After the first time delay relay turns off to the normal position shown, the second time delay relay 44 remains on until the door of the elevator car opens to allow current from the first power line to be supplied through such first and second relays to the

auxiliary relays

22 and 28 to hold such auxiliary relays in an energized condition and to allow the auxiliary relay to be energized when the elevator car is stopped. However when the car door opens the third time, delay relay 42 is deenergized so that the normally closed contacts of such relay and of the first time delay relay 34 complete a circuit from the first power line to the solenoid winding of the

auxiliary relays

22 and 28 to hold such relay in an energized condition.

The solenoid winding of the third time delay relay 42 is connected through a lead 46 to the first power line through an elevator car door contact switch 48, a stop switch 50' on top of the car, an emergency push button switch 52 inside the car, a pit stop switch 54 and lead 38. Thus, when the car door of the elevator is closed, the third time delay relay 32 is actuated, and after a time delay turns on to close the normally open contacts of such relay. This time delay enables passengers getting on the elevator to make their floor selections before the main up relay and down valve 24 are again energized through the normally closed contacts of the second time delay relay 44 and the normally closed fifth pair of contacts on the

auxiliary relays

22 and 28 from the first power line through a lead 56 which is connected through the door switches 58, 60 and 62 of the hall entrance or hoistway door on the first, second and third floors, respectively, by way of

switches

48, 50, 52 and 54.

The preferred embodiment of the automatic elevator control circuit of the present invention shown provides for operation of the car between three floors by means of a first floor relay 64, a pair of

second floor relays

66 and 68 and a third floor relay 70. Each of these floor relays is actuated by a different hall push button switch located on the floor with which such relay is associated. Thus, a first floor push button switch 72 completes the circuit between a lead 74, connected to the first power line through lead 40, and one of the terminals of the solenoid winding of the first floor relay whose other terminal is connected to the second power line through a lead 76. Thus, momentary depression of the first floor push but ton 72 energizes the solenoid winding of the first floor relay-64 and closes the normally open pairs of contacts of such relay to complete a circuit through its second pair of contacts from such solenoid winding to the first power line through

leads

77 and 78 and switches 50, 52 and 54. This holds the relay 64 in an energized condition until an auxiliary switch contact 80 on the hoistway door of the first floor is opened.

In a similar manner, the solenoid windings of the

second floor switches

66 and 68 are connected to a down push button switch 82 and an up push button switch 84, respectively, on the second floor which complete circuits from the first power line through

leads

74 and 40 to such windings. The other terminals of the solenoid windings of the

relays

66 and 68 are connected to the second power line through lead 76 so that momentary closing of the

push button switches

82 or 84 energizes the relays 66 on 68. In addition, one of the normally open second pair of contacts on each of the

second floor relays

66 and 68 is connected through auxiliary hoistway door switches 86 and 88, respectively, to the first power line by way of lead 78 and the other of such second pair of contacts is connected to the solenoid windings of such relays .to hold the second floor relays in an energized condition after the push buttons are released. Likewise, the solenoid winding of the third floor relay 70' is connected through a third floor push button 92 between the first power line through lead 74 and the second power line through lead 76. The second pair of normally open contacts on the relay 70 are also connected between one terminal of its solenoid winding and the first power line voltage auxiliary hoistway door switch 92 which is closed by closing the hall entrance or hoistway door on the third floor to hold the relay in an energized condition.

A pair of

control relays

94 and 96 are provided for the

second floor relays

66 and 68. One terminal of each of the solenoid windings of such control relays is conected to a dilf-erent fixed contact of an automatic actuating switch 98 having a movable contact connected to the first power line through a lead 97. This movable contact of switch 98 has three switch positions including an upper position connected to relay 96 when the elevator car is above the second or intermediate floor, a middle position when such car is at the second floor and a lower position connected to relay 94 when the car is below the second floor. In the second or middle position of the switch 98, the movable contact of such switch is not connected to either of the fixed contacts so that neither of the control relays is energized. The automatic actuating switch 98 may be a cam operaed switch located within the shaft or hoistway at the second floor so that its movable contact is engaged by a cam mounted on the elevator car.

During the operation of the circuit of FIG. 1, the first floor relay 64 is energized by momentarily pressing the hall push buttons 72 or a push button switch 99 located in the car and connected to the same terminal of the solenoid winding of such relay. This closes the normally open contacts of the first floor relay and they are held in this condition by current flowing through auxiliary door switch 80. The third pair of contacts of such relay 64 completes a circuit through the normally closed first pair of contacts of the second floor down relay 66 and the normally closed fifth pair of contacts on the auxiliary up relay 28 to the first power line by way of the second and third time delay relays. As a result, current flows through a lower limit switch 100 connected to relay 64 and the normally closed first pair of contacts on the auxiliary up relay 28 through the normally closed seventh pair of contacts on relay 10 to the down valve 24. This opens the valve and the elevator is lowered until it reaches the first floor where such elevator trips the lower limit switch 100 deenergizing the valve and stopping the elevator.

In a similar manner, the elevator car is called to the third floor by momentarily depressing the hall push button or a third floor car push button 102 which is connected between the first power line and one of the terminals of the solenoid winding of such relay. Thus, the third floor relay is energized and is held in this state by current flow through the auxiliary hoistway door switch 92. This closes the normally open third pair of contacts of the third floor relay 70 and completes the circuit between the solenoid winding of the main up relay 10 and the first power line through second and third time delay relays, the normally closed first pair of contacts on the second floor up relay 68 and the normally closed fifth pair of contacts on the auxiliary down relay 22 by way' of the upper limit switch 104, the normally closed first pair of contacts on the auxiliary down relay 22 and the normally closed fourth pair of contacts on the main down relay 30. This actuates the main up relay 10 and energizes the motor 18 causing the elevator car to move upward until it reaches the third floor and opens the upper limit switch 104 which stops the elevator motor. Of course, when the'hall hoistway door is opened on the third floor, switch 92 is opened and the third floor relay 70 is deenergized.

The above description of operation of the control circuit of the present invention assumes that none of the push. button switches activated the relays of the other floors. However, when the elevator is resting on the third floor and is called by a person on the first floor depressing push button 72, another person on the second floor may. press the down push button 82 to actuate the seconu floor down relay 66 while the elevator car is still above the second floor. As a result of its actuation, the normally closed first pair of contacts on the relay 66 are opened so that current can no longer flow through the third pair of contacts on the energized first floor relay 64 to the down valve, thereby acting as a temporary override for such first floor relay. Since the automatic actuating switch 98 is in the up position at this time due to the location of the elevator, control relay 96 is energized and the second pair of contacts of such control relay are closed. This completes an electrical circuit to the first power line through the third pair of contacts on the second floor down relay 66, the normally closed first pair of contacts on a bypass relay 106, the normally closed fifth pair of contacts on the auxiliary up relay 28 and the second and third time delay relays 44 and 42. This circuit transmits current through the second pair of contacts on the control relay 96, the lower limit switch 100, the normally closed first pair of contacts of the auxiliary up relay 28 and the seventh pair of contacts of the main up relay to the down valve 24 causing the elevator to move down.

When the elevator car reaches the second floor position it is stopped due to the movement of the movable contact of the automatic actuating switch 98 to the middle position to deenergize the control relay 96. The second floor down relay 66 is deenergized by the opening of the hall hoistway door to open the auxiliary door switch contacts 86 and the first pair of of contacts on such relay are closed to again complete the circuit between the down valve 24 and the first power line through the first floor relay 64 so that such first floor relay is then again in control of the operation of the elevator. It should be noted that at the same time the down valve 24 is activated the main down relay 30 is also energized to close the second pair of contacts of such relay which completes the circuit through the normally closed second pair of contacts on the auxiliary up relay 28 to the solenoid winding of the auxiliary down relay 22 to actuate such auxiliary down relay. This opens the first pair of contacts on the auxiliary down relay 22 and prevents the main up relay from being energized.

The disenabling or override operation described above with respect to the first floor relay 64 does not happen if the second floor down relay 66 is energized when the elevator car is below the second floor and is moving down because the bypass relay 106 is actuated at this time. This bypass relay functions to shunt or bypass current around the override condition of the opened first pair of contacts on the relay 66. The solenoid winding of the bypass relay 166 is connected to the first power line through the first pair of contacts on control relay 94 which is now energized by actuating switch 98, through the second pair *of contacts on the auxiliary up relay 28 and the second pair of contacts on the main down relay 30. Thus, the bypass relay is energized at this time and its second pair of contacts are closed to connect the third pair of contacts on the first floor relay 64 to the first power line through the fifth pair of contacts on the auxiliary up relay 28 and the second and third time delay relays 44 and 42 so that the first floor relay can actuate the down valve 24 and the main down relay. Therefore, the selective collective automatic operation is maintained. The selective collective type of automatic operation of an elevator is one in which all up landing calls are answered when the car is traveling in the up direction and all down calls 'when the car is traveling in the down direction except in the case of the uppermost or lowermost calls which are answered as soon as they are reached irrespective of the direction of travel of the car. This selective collective automatic operation is defined in greater detail in the American Standard Safety Code for Elevators. A second bypass relay 108 is provided for the override of the third floor relay 70 caused by the opening of the first pair of contacts on relay 63. This bypass relay has one terminal of its solenoid winding connected to the first power line through the first pair of normally open contacts on the control relay 96 and the normally closed second pair of contacts on the auxiliary down relay 22 so that such bypass relay is energized only when the car is moving up and is above the second or intermediate floor level so that the automatic selector switch 98 is in the 'upper position. Since the third pair of contacts of the third floor relay 70 are connected through the first pair of contacts on the second floor up relay 68 to the first line voltage, energization of this second floor relay opens this circuit and overrides the operation of the third floor relay so that it cannot energize the main up relay 10 when the elevator is going down or is going up but is above the second floor. When the bypass relay 108 is energized it connects the third pair of contacts on the third floor relay 70 through another circuit to a source of line voltage and bypasses the second floor relay 68. Thus, the bypass relay 108 allows selective collective up operation in a similar manner to the way in which bypass relay 106 enables selective collective down operation.

' Another point which is not readily apparent is that either the second floor down relay 66 or the second fioor up relay 68 may be operated by a single second floor push button switch 110 located in the elevator car, depending upon the position of the car. Thus, one of the contacts of such push butt-on switch is connected through the third pair of contacts on both of the control relays 94 and 96 to the solenoid windings of the second floor relays 68 and 66, respectively. Thus, the second floor car push button 110 will only energize the second floor up relay 68 when control relay 94 is energized by the automatic actuation switch 98 being in its lower position when the car is below the second floor level. Similiarly, the second floor car push button will only energize the solenoid 'coil of the second floor down relay 66 when the control relay 96 is energized by the automatic actuating switch 98 being located in the upper switch position due to the fact that the car is above the second floor. Thus, the second floor car push button automatically selects the proper second floor relay from the pair of

relays

66 and 68 due to the position of the automatic actuating switch 98. It should be noted that this automatic actuating switch may, in addition to the conventional cam operated switch described above, also be in the form of remotely located switch which is operated by a radio transmitter and receiver combination or may be a magnetically actuated switch mounted on the car which is activated by a .pair of permanent magnets of opposite polarity positioned in the elevator shaft on opposite sides of the second floor position of the magnetic actuated switch.

It will be obvious to those having ordinary skill in the art that many other changes may be made in the details of the above described preferred embodiment of the present invention without departing from the spirit of the in- VentiOn. For example, additional intermediate floors may be added, as desired, along with accompanying circuitry similar to that of the second floor

circuitry including relays

66, 68, 94 and 96 and the other necessary circuit modifications. Therefore, the scope of the present invention should only be determined by the following 'claims.

I claim:

1. An elevator control circuit comprising:

motor means for raising and lowering an elevator;

a first switch means connected to said motor means for lowering the elevator to a bottom position;

at least one .pair of second switch means connected to said motor means for raising and lowering the elevator by a different one of said pair of second switch means to an intermediate position;

a third switch means connected to said motor means for I raising the elevator to a top position;

a pair of control means each connected between a different one of said pair of second switch means and said motor means for controlling when said pair of second switch means can be operated to energize said motor means;

automatic actuating means for causing one of said control means to operate when the elevator is above said intermediate position and for causing the other of said control means to operate when the elevator is below said intermediate position; and

disenabling means connecting said first and third switch means through different ones of said pair of second switch means to said motor means, for preventing said first and third switch means from operating said motor means when said second switch means energize said motor means.

2. An elevator control circuit comprising:

motor means including a main up switch and a main down switch, for raising and lowering an elevator;

at least one pair of second switch means connected to said motor means for raising and lowering the elevator by a different one of said pair of second switch means to an intermediate position;

a third switch means connected to said motor means for raising the elevator to a top position;

a pair of control means each connected between a different one of said pair of second switch means and said motor means for controlling when said pair of .second switch means can be operated to energize said motor means;

disenabling means connecting said first and third switch means through different ones of said pair of second switch means to said rnain down switch and said main up switch, respectively, for preventing said first and third switch means from operating said motor means when said second switch means energize said motor means.

3. An elevator control circuit comprising:

motor means for raising and lowering an elevator;

a pair of control switch means each connected between a different one of said pair of second switch means and said motor means for controlling when said pair of second switch means can energize said motor means;

automatic actuating means for causing one of said control switch means to operate when the elevator is above said intermediate position and for causing the other of said control switch means to operate when the elevator is below said intermediate position;

disenabling means connecting said first and third switch means through different second switch means to said motor means, for preventing said first and third switch means from operating said motor means when said second switch means energize said motor means; and

a plurality of manual actuating means for operating each of said first, second and third switch means, with one of the manual actuating means being connected through said pair of control switch means to said pair of second switch means so that said control 4. An elevator control circuit, comprising:

motor means for raising and lowering an elevator;

a first relay means connected to said motor means for lowering the elevator to a bottom position;

a pair of second relay means connected to said motor means for raising and lowering the elevator by a different one of said pair of second relay means to an intermediate position;

a third relay means connected to said motor means for raising the elevator to a top position;

a pair of control relay means each connected between a different one of said pair of second relay means and said motor means for controlling when said pair of second relay means can be operated to energize said motor means;

cam switch actuating means for causing one of said control relay means to operate when the elevator is above said intermediate position and for causing the other of said control relay means to operate when the elevator is below said intermediate position;

said first and third relay means each being connected through a different second relay means to said motor means, for preventing said first and third relay means from operating said motor means when said second relay means energize said motor means; and

plurality of manual switch actuating means for operating each of said first, second and third relay means, including a first hall switch and a first car switch connected to said first relay means, a pair of second hall switches connected to different ones of said pair of second relay means and a second car switch connected through each of said control relay means to each of said second relay means, and a third hall switch and a third car switch connected to said third relay means.

5. An elevator control system, comprising:

a first relay having its solenoid winding connected to a first floor hall switch and a first floor elevator car switch;

a pair of second relays each having their solenoid windings connected to a different one of a pair of second floor hall switches and to a second floor car switch;

a third relay having its solenoid winding connected to a third floor hall switch and a third floor ca=r switch;

a pair of control relays each having its solenoid winding connected to a different contact of a three position automatic actuating switch so that a different one of said control relays is energized in each'of two positions of said automatic switch and neither of said control relays are energized in the third position of said automatic switch, each of said control relays being connected to a different one of said second relays to control when said second relay can cause the elevator car to move;

a main up relay having its solenoid winding connected through an upper limit switch to one of said second relays through one of said control relays and to said third relay; and

a main down relay having its solenoid winding connected through a lower limit switch, the other of said 7 second relays and the other of said control relays to said first relay.

6. An elevator control system, comprising:

a first relay having its solenoid winding connected to a first floor hall switch and first floor elevator car switch;

a third relay having its solenoid winding connected to a third floor hall switch and a third floor car switch;

a pair of control relays each having its solenoid winding connected to a different contact of a three position automatic actuating switch so that a different one of said control relays is energized in each of two positions of said automatic switch and neither of said control relays are energized in the third position of said automatic switch, each of said control relays being connected to a different one of said second relays to control when said second relay can cause the elevator car to move;

a main up relay having its solenoid Winding connected through an upper limit switch to one of said second relays through one of said control relays and to said third relay;

a main down relay having its solenoid winding connected through a lower limit switch, the other of said second relays and the other of said control relays to said first relay;

an auxiliary up relay having its solenoid winding connected to said main up relay;

said first relay being connected through said other second relay and said auxiliary up relay between a source of electrical current and said valve so that actuation of either said other second relay or said auxiliary up relay overrides said first relay and prevents it from energizing the lower mechanism of the elevator car;

an auxiliary down relay having its solenoid winding connected to said main down relay; and

said third relay being connected through said one second relay and said auxiliary down relay between a source of electrical current and the solenoid of said main up relay so that actuation of either said one second relay or said auxiliary down relay overrides said third relay and prevents it from energizing said rnain up relay.

7. A selective collective elevator control system, comprising:

said first relay being connected through said other second relay and said auxiliary up relay between a source of electrical current and said valve so that actuation of either said other second relay or said auxiliary up relay overrides said first relay;

an auxiliary down relay having its solenoid winding connected to said main down relay;

10 said third relay being connected through said one second relay and said auxiliary down relay between a source of electrical current and the solenoid of said main up relay so that actuation of either said one second relay or said auxiliary down relay overrides said third relay and prevents it from energizing said main up relay; first bypass relay having a pair of normally open contacts connected between said auxiliary up relay and said first relay across said other second relay to prevent the override of said first relay when said first bypass relay is energized, said first bypass relay having its solenoid winding connected to a source of electrical current through said one control relay; and a second bypass relay having a pair of normally open contacts connected between said auxiliary down relay and said third relay across said one second relay to prevent the override of said third relay when said second bypass relay is energized, said second bypass relay having its solenoid winding connected to a source of electrical current through said other control delay. 8. A selective collective elevator control system, cornprising:

a pair of control relays each having its solenoid winding connected to a different contact of a three position automatic actuating switch so that a different one of said control relays is energized in each of two positions of said automatic switch and neither of said control relays are energized in the third position of said automatic switch, each of said control relays being connected to a different one of said second relays to control when said second relays can cause the elevator to move;

an electric motor adapted to raise the elevator car;

a main up relay having its solenoid winding connected through an upper limit switch to one of said second relays through one of said control relays and to said third relay, and having at least one normally open pair of switch contacts connected between a source of electrical current and said motor;

an electrically actuated valve adapted to control a fluid system in a manner to lower said elevator car;

a main down relay having its solenoid winding connected to said valve and through a lower limit switch, the other of said second relays and the other of said control relays to said first relay;

said first relay being connected through said other second relay and said auxiliary up relay between a source of electrical current and said valve so that actuation of either said other second relay or said auxiliary up relay overrides said first relay and prevents it from energizing said valve;

said third relay being connected through said one second relay of said auxiliary down relay between a source of electrical current and the solenoid of said main up relay so that actuation of either said one second relay or said auxiliary down relay overrides said third relay and prevents it from energizing said main up relay;

1 l 1 2 a first bypass relay having a pair of normally open coni pass relay having its solenoid winding connected to a tacts connected between said auxiliary up relay and source of electrical current through said other consaid first relay across said other second relay to pretrol delay. vent the override of said first relay when said first bypass relay is energized, said first bypass relay References Clted y the Examlllel having its solenoid winding connected to a source 5 UNITED STATES PATENTS glfuflectrical current through sald one control relay; 3,056,469 10/1962 Wilson 3,105,573 10/1963 'Leveski 18729 a second bypass relay having a pair of normally open 3,1818 4 4 6/1965 MacNair et a1. 187 29 contacts connected between said auxiliary down relay and said third relay across said one second relay 10 RI L R P to prevent the override of said third relay when 0 S Hmary isxammer' said second bypass relay is energized, said second by- LYNCH, Asslsmm

Claims

1. AN ELEVATOR CONTROL CIRCUIT COMPRISING: MOTOR MEANS FOR RAISING AND LOWERING AN ELEVATOR; A FIRST SWITCH MEANS CONNECTED TO SAID MOTOR MEANS FOR LOWERING THE ELEVATOR TO A BOTTOM POSITION; AT LEAST ONE PAIR OF SECOND SWITCH MEANS CONNECTED TO SAID MOTOR MEANS FOR RAISING AND LOWERING THE ELEVATOR BY A DIFFERENT ONE OF SAID PAIR OF SECOND SWITCH MEANS TO AN INTERMEDIATE POSITION; A THIRD SWITCH MEANS CONNECTED TO SAID MOTOR MEANS FOR RAISING THE ELEVATOR TO A TOP POSITION; A PAIR OF CONTROL MEANS EACH CONNECTED BETWEEN A DIFFERENT ONE OF SAID PAIR OF SECOND SWITCH MEANS AND SAID MOTOR MEANS FOR CONTROLLING WHEN SAID PAIR OF SECOND SWITCH MEANS CAN BE OPERATED TO ENERGIZE SAID MOTOR MEANS; AUTOMATIC ACTUATING MEANS FOR CAUSING ONE OF SAID CONTROL MEANS TO OPERATE WHEN THE ELEVATOR IS ABOVE SAID INTERMEDIATE POSITION AND FOR CAUSING THE OTHER OF SAID CONTROL MEANS TO OPERATE WHEN THE ELEVATOR IS BELOW SAID INTERMEDIATE POSITION; AND