US2972093A - Bidirectional stepping motor servosystem - Google Patents

Description

Feb. 14, 1961 R. J. SILHAVY 2,972,093

BIDIRECTIONAL STEPPING MOTOR SERVOSYSTEM Filed Oct. 10, 1958 470 rweg,

United States Patent BIDIRECTIONAL STEPPING MOTOR SERVOSYSTEM Raymond J. Silhavy, Chicago, 111., assignor to Oak Manufacturing Co., a corporation of Delaware Filed Oct. 10, 1958, Ser. No. 766,482 2 Claims. (Cl. 318-19) This invention relates to a bi-directional switch homing system and more particularly to a system utilizing a multi-position master switch for controlling one or more multi-position slave switch sections.

Master controlled switch systems have wide uses in many fields. As an example, such systems may be used in connection with building elevators and in the remote control of various kinds of apparatus and devices.

Rotary switch systems wherein the position of a slave switch unit is controlled by the position of a master switch unit are well known. In such systems, a master switch unit may be turned by any suitable means to any one of a number of predetermined positions and this will cause the slave systems to follow and move a slave switch section to a corresponding similar position. In such systems, it may be necessary to move the master switch section in a predetermined direction. In such instance a master switch section may be turned from one predetermined position to another through the smallest angle but the slave sections can only travel in a definite direction and will take the longest way around to get to the predetermined position. As a result of such operation, the speed of operation of such a switch system is reduced and results in increased wear on the various components of the system because of the greatly increased operation and travel. A

A system embodying the present invention has great flexibility in permitting a master switch section to be turned in one or other desired direction with the assurance that the slave switch sections will reach the desired position by the shortest amount of travel. It is clear that if rotary motion is involved, there will be two directions that a slave section can take in going from one position to another position. However, one direction will always involve a smaller range of travel than the other direction.

A system embodying the present invention provides that the slave sections will always take the direction of travel which will provide the quickest and shortest travel between two points.

In order that the invention may be understood, reference will now be made to the drawing wherein the single figure illustrates in diagrammatic form a system embodying the present invention. The various switch sections are shown from one side only so that the rear of a switch section will appear as though transparent.

In the operation of the new system, rotary switch sections are used. While many different rotary switch constructions may be used, a switch construction which is convenient and useful is disclosed in United States Patent No. 2,186,949 issued on January 16, 1940.

Also forming a part of the new system is a. solenoid mechanism for stepping the rotary switch along one switch position at a time. While many such stepping means are known and may be used, a rotary solenoid iwhichmay be used with rotary switch sections is disclosed in United States Patent No. 2,812,453 issued November 5, 1957.

Referring specifically to the drawing, there is illustrated master switch section A having a rotor section A1 which may be turned by any suitable means, here symbolically illustrated as knob A2 coupled to the rotor. Switch section A is here illustrated as having 24 positions although this number may be varied to suit requirements. Accordingly, the stator of section A is provided with 24 fixed contacts numbered respectively 1 to 24 inclusive.

Rotor Al has a single tongue as illustrated in the drawing functioning as an active rotary contact which is adapted to cooperate successively with each of the 24 stator contacts. Rotor A1 is connected by wire A4 which functions as a common return from switch section A. Wire A4 is connected to one terminal, here illustrated as the positive terminal of a source of direct current. The connection of rotor A1 may be effected in any one of a number of ways. For example, the reverse side of section A may contain a grounding ring electrically joined to the rotor contact and cooperating with a stator contact. Other means for effecting a ground or common connection to the rotor contact of rotor A1 may be provided.

Cooperating with master switch section A are slave switch sections B-B and C-C respectively. Each of the slave switch sections has two sides which, for convenience, are referred to as B and B and C and C, respectively. As is clearly indicated in the Patent 2,186,949 previously referred to, the stator and rotor of the switch section can have electrical contacts on opposite sides thereof.

The slave switch section must correspond to the master switch section in regard to the numbere of switch positions. Thus, switch sections B-B' and C-C have 24 positions. Referring to switch section B-B', both faces have stator contacts numbered 1 to 12 inclusive arranged as illustrated. Thus, on both faces of slave section BB', stator contacts 1 to 12 are consecutive and in a 24 position switch would subtend an angle of a bit less than Actually a 24 position switch has the 360 subdivided into 25 parts with the angular separation between the center lines of adjacent contacts being about 14.4".

Since B shows the rear face of the switch section as seen from the front, it is evident that stator contacts 1 to 12 of B will be opposite corresponding contacts 1 to 12 of face B. In other words, slave switch section B-B' will have 24 contacts distributed on the stator to cover positions 1 to 12 inclusive and the opposite pairs, such as number 1 or 2 or 3 will be electrically connected together. The same numbers are used for the stator contacts to show switch position and electrical connections. Thus all No. 1 contacts will be connected together. All No. 2 contacts will be connected together and so on.

The rotors for slave section BB' have rotor contacts B1 and B'l on opposite faces thereof. These two rotor contacts are electrically separate from each other. Rotor contact Bl has an active contact extension as illustrated for engaging the stator contacts, said extension having an angular extent of 11 switch positions, this being one less than half of the 24 position range. Rotor contact 8' on the rear face has its active contact engaging part angularly offset 180 from the effective contact portion of B1 and subtends 12 switch positions, one half of the entire range.

Slave switch section C-C is generally similar to slave section B--B. There are two differences. The stator contacts for slave section C-C' are numbered 13 to 24 inclusive and the rotors are reversed.

The rotor contacts on slave sections C-C are identical with B--B' insofar as construction is concerned. But in CC, rotor contact C1 subtends 12 switch positions whereas rotor contact Cl subtends only 11 switch 7 positions. All contacts 1-3 to 24 inclusive are electrically interconnected.

Each of the rotor contacts of the slave sections are provided with a ground stator contact as shown which engages the rotor contact at all times. Ground stator contacts B and B5 are cross-connected to ground stator contacts C5 and (3'5. Thus, ground contact B5 is directly connected by wire to ground contact CS. Ground contact C5 is directly connected by wire to ground contact B5.

The two switch slave sections B-B' and C-C' are coupled to a common shaft and the shaft is mechanically coupled to two rotary solenoids of any desired construction, such as, for example, disclosed in the patent pre viously identified. The solenoid BS is adapted to cooperate electrically with slave section B-B' while solenoid CS is adapted to cooperate with slave section CC. This cooperation determines the direction in which the shaft is turned. In the case of BS, the rotation of the solenoid would be clockwise as seen from the front of the switch section's. Solenoid CS would turn the switch sections in the reverse direction.

As disclosed in the patent, the operating winding of each of the solenoids is electrically coupled through a switch section for cutting off the solenoid current as or just before the switch section reaches the end of its travel 'for one operating cycle to permit the solenoid to return to starting position It is understood that an operating cycle for a solenoid results in the switch section being turned through one switch position.

Each switch control is symbolically illustrated in connection with slave sections BB and CC"by a cam adapted to cooperate with a spring switch contact for momentarily opening the circuit of an operating winding. Inasmuch as this switch control action of the solenoid is fully disclosed in the patent referred to above, a detailed description thereof will not be given here.

Solenoids BS and CS have one terminal on each of their respective operating windings connected to what is here illustrated as the negative terminal of the direct current power source. The other terminal of each of the solenoid windings is connected through therespective control switch on the correspondingswitch section to the grounding contact for the rotor of the front face of each slave section.

to the master section position.

One desirable feature of the invention resides in the fact that if the power happens to be cut off from the system, movement of any one of the switch sections will not have any serious effects. In other words, if the power source happens to be dead, and'if master switch section A is moved, it is clear that the slave sections will not operate because of lack of power. However, as soon as the power comes on,the slave switch sections will immediately assume a position corresponding to the master swit-c section.

In order that the operation may be clearly understood,

'let it be assumed that master section A is turned so that rotor A1 makes contact with stator contact No. 6 of A. A circuit will be established from the positive terminal of the power supply through wire A4 and the rotor contact of A to stator contact 6 of A.

From stator contact 6, the circuit will continue to contacts6 of slave section B-B'. Due' to the position of rotor Bl, contact 6 of B' will have not efiect. However, contact 6 of the front face B of the switch section contacts rotor B1. The circuit will continue through ground contact B5 to cause BS to operate. BS will rotate the entire assembly of slave sections clockwise as seen from the front until rotor Bl no longer makes contact with stator contact No. 6 of B. At this point rotor contact Bll will close on contact 5 of B. Position 6 is dead on B1 and Bl when solenoid BS stops at 6. However, this will be ineffective since Bl goes to C5 and the circuit is open. This is because section CC has no connections to any No. 6 contact. Also note that Cl and Cl rotor contacts are not connected to each other.

It should be noted that it makes no difference in which direction master section A is turned to reach contact 6 of section A. It is true that if master section A is turned relativeiy slowly, then the solenoids may be fast enough so that the slave sections will be stepped in the same direction as the master. However, if master section A is turned from contact 1 as shown to contact 6 in a counterclockwise direction (the long way around) and if this is done fast, the action described due to solenoid BS will occur.

The corresponding action will occur with solenoid CS if the master station A is turned to select any one of switch positions 13 to 24 inclusive.

Due to the differences in angularity of the active portions of the rotor contacts B1 and Bl; C1 and C1 and the reversal of the rotor arrangements of sections B--B' and C-C, there will be no point to which the manual control can be turned where the slave sections will be at dead center. in other words, the new system provides for discrete operating positions none of which will be exactly from any previous position. Hence, the slave sections will always have a longer and shorter path of travel from one position to any other position and will automatically select such shorter path. 7

Itis understood that the two rotary solenoids and slave sections will all be coupled to the same shaft although only one solenoid will ever be active at any one time. It is evident that any number of slave systems may be provided, each slave system having its pair of rotary sole-. noids and complement of slave switch sections; Each complete slave system will be connected in parallel to the first slave system so that in effect the master switch section I A will control each slave system.

The master switch section A can be replaced by a push button type of switch for selecting one switch positionat .a time. Y

What is claimed is:

g l. A bi-directional remote control master and slave system adapted to operate over a predetermined number of separate index positions, said system comprising a master switch section, such switch section having a common return and having a number of separate switch contacts corresponding to a number of total operating switch positions, said master switch including means for selecting a switch position so that a corresponding switch contact is connected to said common return, at least one remote slave section, said slave section comprising four oriented rotary switch sections, the first and second switch sections operating as one unit for movement in one direction, the third and fourth switch sections operating as a second-unit for movement inthe opposite direction, a common shaft for all said four switch sections, each switch section including a rotor rotatively coupled to said shaft, each switch section including a stator having a plu- .rality of active contacts, each of the four switch sections having index switch positions equal in number to the switch positions of said master switch section. the first two switch sections having active stator contacts corresponding to the first halfof the total index switch positions with corresponding contacts for the same switch position connected together, the rotors for said first two switch sections each having rotor contact, each rotor contact having an active switching portion, the active rotor switching portion of the first switch section subtending an angle equal to one less than one half the number of index switch positions, the active rotor contact for the second switch section subtending an angle equal to one-half the number of index switch positions, the active rotor contact portions of the first two switch sections being angularly displaced by one-half of the total number of index switch positions, the third and fourth switch sections being correspondingly constructed, the third and fourth switch sections having active stator contacts corresponding to the second half of the total index switch positions, the rotor contacts for the third and fourth switch sections being similar to the rotor contacts for the first two switch sections except that the third rotor contact is the one which has the active portion subtending an angle equal to one-half of the index switch positions, wires connecting the active contacts corresponding to the same switch positions of the master switch section and the switch sections, a ground ing contact for each rotor contact of the four switch sections, cross connections between the rotor grounding contact of the first and fourth switch sections on the one 29 hand and between the second and third switch sections on the other hand, stepping means including a winding for stepping said four switch sections one switch position at a time in one direction, similar stepping means including a winding for stepping the four switch sections in the reverse direction, a connection from one terminal from said one stepping means winding to the grounding contact for the rotor of the first switch section, a connection from the one terminal of the other stepping means winding to the grounding contact of the rotor switch section, and a common connection at the remaining terminals of the windings of the two stepping means, said last named common connection and the common return for the master switch section constituting terminals for connection to a source of electric power for energizing the stepping means. 7

2. The system according to claim 1 wherein said master switch section is of the rotary type, said common return therefor including a rotary movable contact cooperating with the separate stator switch contacts.

No references cited.

Images