United States Patent
`
`Inventor
`[72)
`Dale F. Hammer
`Bellbrook, Ohio
`Appl. No.
`[21)
`870,628
`Filed
`Dec. 15,1969
`[22)
`[45)
`Patented
`May 25,1971
`Assignee
`[73)
`General Motors Corporation
`Detroit, Mich.
`
`[II] 3 581174
`
`'
`
`'
`
`Primary Examiner-O ris L. Rader
`
`Assistant Examiner-K. L. Crosson
`
`
`W. Christen, C. R. Meland and Robert W.
`Attorneys-E.
`Smith
`
`[54) AUTOMATIC REVERSING CIRCUIT
`FOR A
`WINDOW REGULATOR MOTOR CONTROL
`ABSTRACT: A window regulator motor control system for a
`
`SYSTEM
`
`
`drive motor operative to open and close a window includes an
`2 Claims, 2 Drawing Figs.
`
`
`
`
`automatic reversing circuit incorporating an overload current
`£52! u.s. c1........................................................
`318/266,
`
`relay and a reversing relay which function to reverse the
`
`
`318/285. 318/297. 318/466
`
`motor in response to an overload current condition. The
`[51) Int. Cl.........................................................
`H02p 1/22
`
`
`reversing relay is energized through a controlled rectifier
`
`[50) FieldofSearch............................................ 318/266,
`
`
`
`a resistance­circuit including gated conductive by a triggering
`
`
`296,297,285,466
`
`capacitance time delay network connected to the overload
`current relay. When the window is driven against an obstruc­
`References Cited
`
`tion, the time delay network provides a momentary delay be­
`UNITED STATES PATENTS
`
`
`
`fore the controlled rectifier is gated conductive and the motor
`3,513,374 5/1970 Koment.. ........
`............
`.. 318/266
`is reversed.
`
`[56)
`
`

`
`PATENTED
`MAY251071
`
`.
`
`.
`
`3,581,17 4
`
`INVENTOR
`tJale § llammer
`
`BY
`Pdal a!�
`ATTORNEY
`
`

`
`3,581,174
`
`1
`
`2
`AUTOMATIC REVERSING CIRCUIT FOR A WINDOW
`
`Referring to FIG. 1 of the drawing, there is shown an au­
`
`REGULATOR MOTOR CONTROL SYSTEM
`
`tomotive vehicle body 8 with a window opening 10 including a
`This inventi?n relates to motor driven window regulators
`window closure member provided by a movable window l2
`
`
`and more parttcularly to a motor control system including a
`
`which is retractable into a hollow body section 14. A window
`
`
`reversing circuit responsive to an obstacle impeding move­
`
`5 regulator 16 mounted in the body section 14 moves the win­
`ment of the window regulator.
`
`dow 12 between the closed and open positions. An electric
`The use of remotely controlled and power assisted devices
`
`
`
`drive motor 18 powers the window regulator 16 in accordance
`
`
`are now commonplace in automotive vehicles and in particu­
`
`
`with operation of a window regulator motor control system
`
`
`lar electrically powered window regulators are more
`
`20. A manually operated switch 22, accessible to an occupant
`10
`
`
`frequently found among the accessory items included in au­
`
`of the vehicle body 8, provides remotely controlled operation
`
`
`
`tomobiles. Operation of remotely controlled automobile win­
`
`
`of the motor control system 20 as described hereinbelow in
`
`dows can include instances of a window engaging an obstruc­
`
`
`connection with description of FIG. 2.
`
`tion without the knowledge of the operator. This may occur,
`
`
`The window regulator 16 includes a linkage mechanism cor-
`for example, when an occupant in a forward compartment
`IS responding
`
`
`to that disclosed in U.S. Pat. No. 3,069,152, issued
`
`closes a window in a rearward compartment. In the case of a
`Dec. 18, 1962 and assigned to the assignee of this invention,
`
`window being driven against an obstructing object for an ex­
`
`
`
`which is illustrative of a suitable window regulator mechanism
`
`tended time, possible damage can occur to the window regula­
`adapted to be powered by motor drive means such as the
`
`tor mechanism or to the motor as a result of increased motor
`
`
`motor 18. The linkage mechanism generally includes a pair of
`current which develops because rotation of the motor is
`20 pivot arms 24 and 26 having upper ends connected to the win­
`blocked.
`
`dow 12 by a slotted channel28. The motor 18 is drivingly con­
`
`
`In accordance with the present invention, a remotely con­
`
`nected to the window regulator 16. through a gear arrange­
`
`
`trolled window is automatically retracted in response to an ob­
`
`ment including a pinion gear 30 and a sector gear 32 fixedly
`
`
`an �truction impeding closure of the window by incorporating
`mounted on the arm 26. The motor 18 is mounted on the
`
`
`
`tmproved automatic reversing circuit in the window regulator
`25 lower end of the arm 24 which pivots about a fixed pivot point
`
`motor control system. More specifically, an overload current
`
`36. The arm 26 has a lower end slidably mounted to the vehi­
`
`relay and a reversing relay are provided to switch the motor so
`cle body by a cam channel 38.
`as to open the window in response to an overload current con­
`The motor 18. is a series type direct current motor including
`
`dition. The reversing relay includes relay contacts connected
`a first field winding 40, a second field winding 42, and an ar-
`
`to the motor so as to bypass the normal motor power circuit. A
`
`30 mature 44. The motor circuit includes the field windings 40
`
`
`semiconductor controlled rectifier energized the reversing
`
`and 42 connected in separate series circuits with the armature
`
`
`
`relay and is gated conductive by a triggering circuit connected
`
`44 which is externally connected to a source of reference
`
`�o switch contacts of the overload relay. The triggering circuit
`
`
`motor potential at a grounded connection 45. A rotatable
`
`
`mcludes a resistance-capacitance time delay network having a
`
`
`con-shaft 46 associated with the armature 44 is operatively
`
`capacitor which begins charging when the switch contacts
`35 nected to the pinion gear 30. The field windings 40 and 42 are
`close in response to motor overload current developed when
`
`
`selectively energizable to rotate the motor shaft 46 clockwise
`the window is being closed. Voltage developed across the
`
`and counterclockwise so at to raise and lower, respectively,
`
`
`
`capacitor renders the controlled rectifier conductive after a
`the window 12.
`
`momentary time delay as determined by the time constant of
`THe motor control system 20 includes a motor power cir-
`the ti�e delay network. The controlled rectifier energizes the 40
`
`
`
`
`
`cuit 50 and an automatic reversing circuit 52 provided by the
`
`reversmg relay and the relay contacts close to interrupt the
`
`
`
`present invention. The power circuit 50 includes the manually
`motor current and reconnect the motor for reverse rotation.
`operated switch 22 connected between the motor 18 and a
`
`The window is driven open to free the obstruction imposed on
`source of direct current voltage provided by a battery 54. The
`
`
`the operation of the window regulator and to eliminate the
`
`
`
`
`
`automatic reversing circuit 52 includes reversing relay 56 and
`overload current condition.
`45
`
`
`an overload current relay 58 respectively including a reversing
`
`
`Accordingly, an object of the present invention is to provide
`relay contact assembly 60 and a current relay winding 62,
`
`
`an improved automatic reversing circuit arrangement for a
`
`both connected in the power circuit 50 as described herein­
`
`
`window regulator drive motor in which simple and reliable cir­
`below.
`
`cuit components are easily incorporated in a window regulator
`50 THe battery 54 has the positive pole thereof connected
`
`
`motor control system so as to reverse the rotation of the drive
`
`
`
`through an ignition switch 66 to a circuit junction 68 to supply
`motor in response to an overload current condition.
`
`
`both the power circuit 50 and the automatic reversing circuit
`
`A further object of this invention is to provide an automatic
`52. The negative pole of the battery 54 is connected to the
`
`
`reversing circuit for a window regulator drive motor having
`reference
`
`
`potential at a grounded connection 70.
`two field windings wherein an overload relay senses the cur­
`55 The power circuit 50 is connected to the junction 68 by the
`
`
`rent in one of the field windings and a series circuit including a
`
`relay 56. The contact as­contact assembly 60 of the reversing
`
`
`
`
`
`controlled rectifier energizes a relay coil of a reversing relay
`
`sembly 60 includes a movable contact arm 72, a normally
`
`
`having contacts operative to interrupt the current in the one
`closed contact 74 and a normally open contact 76. The arm 72
`field windings and to energize the other field winding and
`includes common contact 77 which engages the normally
`
`
`further, a triggering circuit connected between switch con­
`60 closed contact 74 when a relay coil 78 included in the
`
`tacts of the overload current relay and the controlled rectifier
`
`
`reversing relay 56 is deenergized. The contact arm 72 is con­
`
`
`gates the latter conductive so as to energize the reversing relay
`
`nected to the circuit junction 68 and is operated by an arma­
`
`after a predetermined delay period thereby avoiding reversing
`
`ture 80 movable in response to energization of the relay coil
`
`of the motor in response to instantaneous surges of high cur­
`
`78 to disengage the contact 74 and engage the contact 77 with
`rent.
`65 the contact 76.
`
`
`Further objects and advantages of the present invention will
`The manually operated switch 22 is connected between the
`
`
`
`be apparent from the following description, reference being
`
`norinally closed contact 74 and the motor 18 to selectively
`
`
`had to the accompanying drawing wherein a preferred em­
`energize the field windings 40 and 42. A switch lever 82 is
`
`bodiment of the present invention is shown.
`
`movable between two positions to engage contacts 84 and 86.
`
`FIG. 1 is a partial side elevational view of an automotive
`
`The contact 84 is desrgnated "Close" and is connected with
`
`vehicle body illustrating a window regulator actuated by a 70
`
`
`the field winding 40 and the contact 86 is designated "Open"
`
`
`window regulator motor control system including the auto­
`and is connected with the field winding 42. The switch lever
`
`
`matic reversing circuit of this invention.
`
`82 ls normally biased intermediate the contacts 84 and 86 so
`
`FIG. 2 is a schematic electrical diagram of the window regu­
`
`that the motor is not energized until the switch lever 82 con-
`
`lator motor control system and the automatic reversing circuit
`
`75 tacts either of the contacts 84 or 86.
`of this invention.
`
`

`
`3,581,174
`
`4
`3
`The winding 62 provided in the overload current relay 58 is
`the controlled rectifier 106 is gated conductive in accordance
`
`
`
`
`connected intermediate the contact 84 and the field winding
`
`
`with the well known characteristics of a semiconductor con­
`
`trolled rectifier.
`
`
`40. The winding 62 is current sensitive and is responsive to ex­
`The time delay network provided by the resistor 128 and
`
`cessive or high current levels conducted through the field
`winding 40. The switch contact assembly 88 of the overload 5
`
`
`
`the parallel connected resistor 130 and the capacitor 132 has
`
`
`a predetermined resistance-capacitance (RC) time constant
`
`
`current relay 58 includes normally open contacts 90 and 92 of
`
`
`
`to keep the gating of the controlled rectifier 106 insensitive to
`
`a reed switch inductively coupled with the winding 62. In a
`
`an instantaneous closing of the contacts 90 and 92. This may
`
`preferred embodiment the winding 62 is wound around the
`
`occur, for example, when the field winding 40 is initially ener-
`reed switch so that the magnetic field developed by the wind-
`ing 62 draws the contacts 90 and 92 together when the current I 0
`
`
`gized and an instantaneous surge of starting current occurs.
`
`
`The surge of starting current is sufficient to cause the relay
`through the winding 62 reaches a predetermined level.
`
`
`winding 62 to momentarily close the contacts 90 and 92. It has
`The field winding 42 is connected by a conductor 93 to the
`
`been found that a surge of starting current exists for approxi­
`contact 86 of the manually operated switch 22. The field
`
`mately 0.1 second. Accordingly, the RC time constant of the
`winding 42 is also connected to the normally open contact 76
`15
`
`time delay network has a predetermined value such that 0.2
`of the relay contact assembly 60 by a conductor 94 at a circuit
`
`
`132 is charged suffi­junction 96 formed with the conductor 93. The contact 76 and second is required before the capacitor
`
`
`ciently to develop a voltage at the junction 136 to render the
`the conductor 94 provide a path which bypasses the manually
`
`
`
`controlled rectifier 106 conductive. Thus, a high current level
`operated switch 22 so that the field winding 42 is energized
`must flow through the relay winding 62 for at least 0.2 second
`from the battery 54 when the contact arm 72 engages 20 directly
`
`
`
`
`in order to render the controlled rectifier 106 conductive and
`the contact 76.
`
`
`energize the reversing relay coil 78.
`
`
`is The motor power circuit SO described hereinabove
`
`During normal operation of the window actuator 16, the
`
`
`rendered operative when the ignition switch 66 is closed to
`
`
`switch lever 82 is moved to the "Close" position to energize
`connect the switch lever 82 of the switch 22 through the nor­
`
`25 the field winding 40 from the series circuit including the bat­
`mally closed contact 74 of the relay contact assembly 60. The
`
`tery 54, the ignition switch 66, the normally closed contact 74,
`manually operated switch 22 is then operable to apply battery
`the contact 84 and the relay winding 62. The motor shaft 46 is
`voltage across either of the field windings 40 or 42 and the ar­
`
`
`rotated clockwise to drive the window regulator 16 to a win­
`mature 54 when the switch lever 82 is placed in the "Close" or
`
`dow raised or closed position. To lower the window 12, the
`"Open'' positions.
`
`30 switch lever 82 is placed in the "Open" position to engage the
`Referring now to the automatic reversing circuit 52, the
`
`
`
`
`contact 86 and energize the field winding 42 as described for
`
`
`reversing relay 56 is energized through a series circuit com­
`the field winding 40.
`prising conductor 102 connected to the junction 68, a limit
`During the window raising mode of operation, an object in
`
`
`
`switch 104, and a controlled rectifier 106 connected between
`the window opening 10 can block further closing of the win-
`
`limit switch 104 and the reversing relay coil 78. The limit
`
`35 dow 12. The current supplied to the field winding 40 increases
`
`switch 104 includes a stationary contact 108 and a movable
`because the motor shaft 46 is stopped since the torque on the
`contact member 109. The contact member 109 engages the
`shaft exceeds the output· of the motor 18. As the current
`
`
`stationary contact 108 and includes conductive contact sur­
`through the first field winding 40 begins to reach the overload
`
`face 110 located between two nonconductive contact surfaces
`
`or stalled condition, the current through the relay coil 62
`111 and 112. The contact member 109 is mounted in a suita­
`40 develops a magnetic field sufficient to close the contacts 90
`
`ble location for movement with the window 12, for example,
`and 92. The time delay network is then connected across the
`
`
`on the sector gear 32. Therefore, the conductive surface 110
`
`
`battery 54 and the capacitor 132 charges in accordance with
`
`and nonconductive surfaces 111 and 112 are moved relative
`
`the aforementioned RC time constant provided by the re­
`
`
`to the stationary contact 108 as the window regulator 16
`
`
`
`sistances of resistors 128 and 130 and the capacitance of the
`
`
`operates between raised and lowered window positions. The
`
`
`junction 136 rises so 45 capacitor 132. The voltage at the circuit
`
`nonconductive surfaces Ill and 112 engage the contact 108
`
`
`
`that the critical firing voltage of the controlled rectifier 106 is
`
`when the window is within approximately one-half inch of the
`
`
`reached after the predetermined time delay of 0.2 second. The
`
`raised and lowered positions, respectively.
`
`
`current limiting resistor 124 limits the current applied to the
`
`
`
`The controlled rectifier 106 is a semiconductor switching
`
`gate 118 to a safe value so as to prevent damage to the con-
`
`device of the silicon controlled rectifier (SCR) type having
`
`50 trolled rectifier 106.
`
`anode 114, cathode 116, and gate 118 electrodes. The anode
`The controlled rectifier 106 in the conductive state provides
`
`
`
`114 is connected to the movable contact member 109 of the
`
`a low resistance path between the anode 114 and cathode 116.
`limit switch 104. The cathode 116 is connected to the upper
`
`
`Accordingly, the reversing relay winding 78 is connected
`
`end 119 of the relay coil 78. The series circuit of the relay coil
`across the battery 54. The limit switch 104 will be positioned
`
`78 is completed by connecting the lower end 120 of the relay
`
`
`contact 55 so that the conductive surface 110 engages stationary
`
`coil 78 to a grounded connection 121. The gate 118 of the
`
`108 and provides a closed circuit path. Upon energization of
`
`
`
`
`controlled rectifier 106 is connected to a triggering circuit 122
`
`the reversing relay coil 78, the contact arm 72 is moved by the
`
`
`
`operative to bias the controlled rectifier 106 conductive.
`
`armature 80 to engage the normally open contact 76. This in­
`
`
`The triggering circuit 122 includes a current limiting re­
`
`
`the power circuit energizing the field winding 40 and
`terrupts
`
`sistor 124 and a time delay network formed by a resistor 128
`
`60 the overload current condition in the motor 18 is removed.
`
`
`
`and a resistor 130 connected in parallel with a capacitor 132.
`
`
`The electromagnetic field of the relay coil 62 collapses and
`
`The resistor 124 is connected between the gate 118 and a cir­
`the associated switch contacts 90 and 92 are opened. Thus,
`
`cuit junction 136 which is formed between one of common
`
`
`the triggering circuit 122 is disconnected from the battery 54
`
`
`ends of the resistor 130 and the capacitor 132 and one end of
`
`
`
`
`although the controlled rectifier 106 continues conducting in
`
`the resistor 128. The other of the common ends of the resistor
`
`
`65 accordance with the conventional characteristics of a con­
`
`130 and the capacitor 132 is connected to the reference
`
`
`
`trolled rectifier. Voltage stored on the capacitor 132 will drain
`
`potential provided at a grounded connection 138. The trigger­
`
`
`off through the resistor 130 to ground, discharging the capaci­
`
`
`ing circuit 122 is completed by connecting the remaining end
`tor 132.
`
`of the resistor 128 to contact 92 of the switch contact as­
`Upon closing of the contact arm 72 with the normally open
`
`sembly 88 and connecting the contact 90 to a circuit junction
`70 contact 76, the field winding 42 is connected to the battery 54.
`
`142 formed with the conductor 102. Thus connected, the trig­
`
`The conductor 94 extending between the normally open con­
`
`gering circuit 122 is connected across the battery 54 when the
`tact 76 and the circuit junction 94 bypasses the manually
`
`
`
`operated switch 22. Therefore, regardless of the position of
`contacts 90 and 92 are closed by the relay winding 62. When
`
`the switch lever 82 and field winding 42 continues to be ener-
`
`
`the potential at the circuit junction 136 applies the critical
`75 gized.
`
`triggering voltage across the gate 118 and the cathode 116,
`
`

`
`3,581 '174
`
`6
`5
`
`overload current relay including a relay winding and a nor­
`
`Energization of the field winding 42 causes the armature 44
`
`
`
`
`
`mally open switch assembly; means connecting said relay
`
`
`to be rotated counterclockwise driving the window regulator
`
`
`
`winding in said motor power circuit in a current sensing rela­
`
`16 to lower the window 12 toward its opened position. Con­
`
`
`tionship with said first field winding so that said normally open
`
`
`
`sur­tinued lowering of the regulator the conductive 16 rotates
`
`por-5
`
`
`
`switch assembly is closed in response to an overload current
`face 110 of the limit switch 104 until the nonconductive
`tion ll2 engages the fixed contact 108. The series circuit in­
`
`
`
`
`developed in said first field winding; means connecting said
`
`
`relay cluding the controlled rectifier I 06 and the reversing
`
`
`
`
`normally open switch assembly and said triggering circuit
`
`
`
`rectifier winding 78 is interrupted to render the controlled 106
`
`across said electrical power source whereby said triggering
`
`
`nonconductive and deenergize the relay coil 78. The contact
`
`
`
`circuit is energized when said normally open switch assembly
`closed I 0
`
`arm 72 is released and returns to engage the normally
`
`
`is closed; and a time delay network included in said triggering
`
`
`
`
`noncon­rectifier contact 74. The controlled 106 is switched
`
`
`
`
`circuit for delaying the application of a trigger signal to said
`
`ductive by interrupting the voltage across the anode to
`
`
`gate electrode for a predetermined time period after said trig­
`
`cathode and it remains nonconductive until the anode to
`
`
`
`
`gering circuit is energized whereby said reversing circuit is in­
`
`
`
`
`cathode voltage is reapplied and a triggering voltage is applied
`
`
`
`sensitive to instantaneously developed high current surges
`15
`to the gate liS.
`through said first field winding.
`
`
`If the manually operated switch lever 82 has been released,
`of a the operation 2. A motor control system for regulating
`
`
`
`
`
`If the switch the window 12 will remain in the opened position.
`
`window closure member in combination with an electrical
`
`
`lever 82 is placed in the "Close" position, the circuit for ener­
`
`
`
`power source; ·a motor including an armature, a first field
`gizing the first field winding 40 is again operable to drive the
`
`
`
`
`winding for rotating said armature in one direction when ener­
`20
`window 12 toward the closed position. As the window closes,
`
`
`
`gized by said electrical power source, and a second field wind­
`
`
`
`sur­so that the nonconductive the limit switch 104 is rotated
`
`
`
`
`ing for rotating said armature in the opposite direction when
`
`face Ill engages the fixed contact 108. Thus, the automatic
`
`
`
`energized by said electrical power source; and a window regu­
`
`
`
`
`and in­is disconnected reversing circuit 52 of this invention
`
`
`
`lator mechanism connected to said armature and to said win­
`
`operative when the window 12 is in either the opened or
`
`
`dow closure member for moving the window closure member
`25
`
`
`
`closed position. Any overload current that may be developed
`
`
`
`
`
`to a closed position in response to rotation of said armature in
`by continuing to energize the windings 40 and 42 from the
`
`
`
`
`
`said one direction and moving the window closure member to
`
`
`
`circuit after the clos-switch 22 does not activate the reversing
`
`
`
`an open position in response to the rotation of said armature
`
`ing and opening operations are completed.
`
`
`
`in said opposite direction; wherein said motor control system
`
`
`
`that the inven-30 From the foregoing description it is apparent
`
`
`
`comprises: a motor power circuit including at least one electri­
`
`
`tion provides a simple and effective means for preventing
`
`
`
`cal switch operable to a first position for connecting said ar­
`
`damage to the motor 18 or the window regulator 16 caused by
`
`mature and said first field winding across said electrical power
`
`
`obstruction preventing the movement of the window 12. The
`
`
`
`source and operable to a second position for connecting said
`
`
`
`motor current automatic reversal of the motor 18 prevents
`
`armature and said second field winding across said electrical
`
`
`
`time after the 35 from reaching an overload level for an extended
`
`
`
`power source; a reversing relay including a relay coil and a
`
`
`
`motor is stopped by an obstruction. The circuit elements com­
`
`
`
`contact assembly connected in said motor power circuit for
`
`prising the automatic reversing circuit 52 may be easily and
`
`
`
`
`
`connecting said electrical switch and said motor across said
`
`
`compactly mounted within a hollow body portion of an au­
`
`electrical power source while said relay coil is deenergized
`
`
`tomotive vehicle as found in a door for example.
`
`
`and for connecting only said armature and said second field
`
`
`While the embodiment of the present invention as herein 40
`
`winding across said electrical power source when said relay
`
`
`
`
`disclosed constitutes a preferred from it is understood that
`
`
`
`
`coil is energized; a reversing circuit including a limit switch
`other forms ma:y be adopted within the scope of this invention.
`
`
`
`having a fixed contact and a movable contact operatively cou­
`What I claim is as follows:
`pled to movement of said window closure member, a con­
`of a the operation 1. A motor control system for regulating
`
`
`
`
`
`
`
`trolled rectifier having two current carrying electrodes con­
`
`window closure member in combination with an electrical
`45
`
`nected in series with said fixed contact and said movable con­
`
`
`power source; a motor including an armature, a first field
`
`
`tact, and connecting said reversing relay coil across said elec­
`
`winding for rotating said armature in one direction when ener­
`
`
`
`
`
`trical power source, the contacts of said limit switch having an
`
`
`gized by said electrical power source, and a second field wind-
`
`
`open contact position in response to said window closure
`
`
`
`
`ing for rotating said armature in the opposite direction when
`
`member being in one of the open or closed positions and a
`energized
`
`
`by said electrical power source; and a winqow regu-50
`
`
`
`closed contact position over intermediate positions between
`
`
`
`lator mechanism connected to said armature and to said win­
`
`
`
`said open or closed positions, said controlled rectifier further
`
`dow closure member for moving the window closure member
`
`
`
`having a gate electrode for energizing said relay coil when said
`
`
`
`
`to a closed position in response to rotation of said armature in
`
`
`
`limit switch is in the closed position in response to the applica­
`
`
`
`said one direction and moving the window closure member to
`
`
`
`cir­a triggering tion of a trigger signal to said gate electrode;
`
`
`
`an open position in response to the rotation of said armature 55
`
`
`
`
`rectifi­of said controlled cuit connected to said gate electrode
`
`
`
`in said opposite direction; wherein said motor control system
`
`
`
`er for applying a trigger signal to said gate electrode when the
`
`
`
`comprises: a motor power circuit including at least one electri-
`
`
`
`
`triggering circuit is energized; an overload current relay in­
`said ar­
`for connecting
`to a first position
`cal switch operable
`
`
`cluding a relay winding and a normally open switch assembly;
`
`mature and said first field winding across said electrical power
`
`means connecting said relay winding in said motor power cir­
`said 60
`for connecting
`to a second position
`source and operable
`
`
`
`cui� in a current sensing relationship with said first field wind­
`and said second field winding across said electrical
`armature
`
`
`is closed in ing so that said normally open switch assembly
`power source; a reversing relay including a relay coil and a
`
`
`
`
`
`
`
`response to an overload current developed in said first field
`in said motor power circuit
`for
`contact assembly connected
`
`
`
`winding; means connecting said normally open switch as­
`switch and said motor across said
`said electrical
`connecting
`
`
`
`sembly and said triggering circuit across said electrical power
`65
`power source while said relay coil is deenergized
`electrical
`
`
`
`source whereby said triggering circuit is energized when said
`and said second field
`only said armature
`and for connecting
`
`
`
`normally open switch assembly is closed; and a time delay net­
`power source when said relay
`winding across said electrical
`
`
`
`
`work connected in said trigger circuit including a fi.rst resistor,
`between said
`connected
`circuit
`a reversing
`coil is energized;
`
`
`
`
`a second resistor connected in series with said first resistor and
`power so,urce and said relay coil including
`a con­
`electrical
`con-70
`
`
`
`a capacitor connected across said second resistor, said time
`electrodes
`carrying
`having two current
`rectifier
`trolled
`
`
`delay network having a predetermined time 'constant for
`nected in series with said relay coil and said electrical
`power
`
`
`
`delaying the application of a trigger signal to said gate elec­
`said relay coil in
`for energizing
`and a gate electrode
`source,
`
`
`trode for a predetermined time period after the triggering cir­
`signal to said gate elec­
`of a trigger
`to the application
`response
`
`
`
`
`cuit is energized whereby said reversing circuit is insensitive to
`to said gate electrode
`of
`connected
`circuit
`trode; a triggering
`signal to said 75
`high current surges occurring
`instantaneously
`developed
`in
`a trigger
`for applying
`rectifier
`said controlled
`is energized;
`
`said first field winding.
`a�
`circuit
`when the triggering
`gate electrode
`
`·