Air compressing apparatus for railway passenger cars

Claim 2

Air compressing apparatus for a railway car comprising a. a wet rotor screw type air compressor; b. a shunt motor connected to drive the compressor and supplied with DC power from a pair of high voltage leads; c. a starting resistor connected in a series circuit with the armature of the motor; d. a by-pass circuit connected in parallel with the starting resistor; e. a main relay having a starting contact in said series circuit which closes when the coil of the relay is energized; f. a low voltage DC circuit including a pair of power leads connected with the coil of the main relay through a contact of a detector means which is closed when the voltage supplied to the motor is above a first level and is open when said voltage is below a second, materially lower level; g. delay means effective upon closure of the starting contact for maintaining the by-pass circuit open for a predetermined length of time and for thereafter completing said circuit; h. the delay means comprises a time delay relay of the off-delay type including a contact in the by-pass circuit which is open when the relay is energized, and a coil connected with the low voltage power leads through an energizing circuit containing a start switch and a normally Closed, second contact of the main relay; and i. the coil of the main relay is connected with the low voltage power leads through an energizing circuit having a first branch containing said contact of the detector means and a normally open, second contact of the time delay relay, and a parallel, second branch containing said contact of the detector means and a normally open, third contact of the main relay.

Claim 3

Apparatus as defined in claim 1 in which the start switch is said contact of the detector means.

Claim 4

Apparatus as defined in claim 1 in which a. said start switch is separate from said contact of the detector means; and b. each of said branches also contains the start switch.

Claim 5

Apparatus as defined in claim 1 including a. a pair of normally closed safety switches, both of which are included in the energizing circuit for the coil of the time delay relay as well as in each branch of the energizing circuit for the coil of the main relay; b. means responsive to compressor discharge temperature for opening one safety switch; and c. means responsive to current drawn by the motor for opening the other safety switch.

Claim 6

Apparatus as defined in claim 4 including a. an unloader for the compressor having a control solenoid which, when energized, causes the unloader to load the compressor; b. a reservoir connected to receive and store air discharged by the compressor; c. a normally closed third safety switch which is opened by means which responds to the pressure in the reservoir; and d. an energizing circuit connecting the unloader solenoid with the power leads of the low voltage circuit and containing the third safety switch and the start switch, but otherwise being independent of the other energizing circuits.

Claim 7

Apparatus as defined in claim 5 including a. a feed pipe for delivering oil to the compressor and containing a normally closed, solenoid operated valve; and b. an energizing circuit connecting the solenoid of said valve with the power leads of the low voltage circuit through said pair of safety switches and said start switch.

Claim 8

Air compressing apparatus for a railway car comprising a. a wet rotor screw type air compressor; b. a shunt motor connected to drive the compressor and supplied with DC power from a pair of high voltage leads; c. a starting resistor connected in a series circuit with the armature of the motor; d. a by-pass circuit connected in parallel with the starting resistor; e. a main relay having a starting contact in said series circuit which closes when the coil of the relay is energized; f. a low voltage DC circuit including a pair of power leads connected with the coil of the main relay through a contact of a detector means which is closed when the voltage supplied to the motor is above a first level and is open when said voltage is below a second, materially lower level; g. delay means effective upon closure of the starting contact for maintaining the by-pass circuit open for a predetermined length of time and for thereafter completing said circuit; h. a pair of normally closed safety switches in the connection between the coil of the main relay and the power leads of the low voltage circuit, one switch being opened by means which responds to compressor discharge temperature and the other being opened by means which responds to the current drawn by the motor; i. a feed pipe for delivering oil to the compressor and containing a normally closed, solenoid operated valve; j. an energizing circuit connecting the solenoid of said valve with the power leads of the low voltage circuit through said pair of safety switches: k. an unloader for the compressor having a control solenoid which, when energized, causes the unloader to load the compressor; l. a reservoir connected to receive and store air discharged by the compressor; m. a normally closed third safety switch which is opened by means which responds to the prEssure in the reservoir; and n. an energizing circuit connecting the unloader solenoid with the power leads of the low voltage circuit and which contains the third safety switch but is independent of the other safety switches.

Claim 9

Air compressing apparatus for a railway car comprising a. a wet rotor screw type air compressor; b. a shunt motor connected to drive the compressor and supplied with DC power from a pair of high voltage leads; c. a starting resistor connected in a series circuit with the armature of the motor; d. a by-pass circuit connected in parallel with the starting resistor; e. a main relay having a starting contact in said series circuit which closes when the coil of the relay is energized; f. a low voltage DC circuit including a pair of power leads connected with the coil of the main relay through a contact of a detector means which is closed when the voltage supplied to the motor is above a first level and is open when said voltage is below a second, materially lower level; g. delay means effective upon closure of the starting contact for maintaining the by-pass circuit open for a predetermined length of time and for thereafter completing said circuit; h. a pair of normally closed safety switches in the connection between the coil of the main relay and the power leads of the low voltage circuit, one switch being opened by means which responds to compressor discharge temperature and the other being opened by means which responds to the current drawn by the motor; i. a feed pipe for delivering oil to the compressor and containing a normally closed, solenoid operated valve; j. an energizing circuit connecting the solenoid of said valve with the power leads of the low voltage circuit through said pair of safety switches: k. an unloader for the compressor having a control solenoid which, when energized, causes the unloader to load the compressor; l. a reservoir connected to receive and store air discharged by the compressor; m. a normally closed third safety switch which is opened by means which responds to the prEssure in the reservoir; and n. an energizing circuit connecting the unloader solenoid with the power leads of the low voltage circuit and which contains the third safety switch but is independent of the other safety switches.

Claim 10

Air compressing apparatus for a railway car comprising a. a wet rotor screw type air compressor, b. a shunt motor connected to drive the compressor and supplied with DC power from a pair of high voltage leads, c. a starting resistor connected in a series circuit with the armature of the rotor, d. a by-pass circuit connected in parallel with the starting resistor, e. a main relay having a starting contact in said series circuit which closes when the coil of the relay is energized, f. detector means having a detector relay maintained in a first position by energization of its winding from the high voltage leads through a control resistance, g. the detector means including a circuit for shunting the control resistance when the detector relay is in a second position, h. a low voltage DC circuit including a pair of power leads connected with the coil of the main relay through a contact of the detector means which is closed when the voltage supplied to the motor is above a first level and is open when said voltage is below a second, materially lower level, and i. delay means effective upon closure of the starting contact for maintaining the by-pass circuit open for a predetermined length of time for thereafter completing said circuit.

Claim 11

Air compressing apparatus for a railway car comprising a. a wet rotor screw type air compressor, b. a shunt motor connected to drive the compressor and supplied with DC power from a pair of high voltage leads, c. a starting resistor connected in a series circuit with the armature of the rotor, d. a by-pass circuit connected in parallel with the starting resistor, e. a main relay having a starting contact in said series circuit which closes when the coil of the relay is energized, f. detector means having a detector relay maintained in a first position by energization of its winding from the high voltage leads through a control resistance, g. the detector means including a circuit for shunting the control resistance when the detector relay is in a second position, h. a low voltage DC circuit including a pair of power leads connected with the coil of the main relay through a contact of the detector means which is closed when the voltage supplied to the motor is above a first level and is open when said voltage is below a second, materially lower level, and i. delay means effective upon closure of the starting contact for maintaining the by-pass circuit open for a predetermined length of time for thereafter completing said circuit.

Claim 12

Apparatus as defined in claim 8 in which the control resistance includes both fixed and variable value portions, and the shunting circuit extends around only the fixed value portion.