DE2923894A1 - ENGINE CONTROL CIRCUIT - Google Patents

Description

PRIORITY:

PATENT APPLICATION

June 16, 1978

(corresponds to US application Serial No. 916 189)

DESIGNATION: Motor control circuit

APPLICANT: Sunbeam Corporation

54-00 West Roosevelt Road Chicago, 111., V.St.A.

INVENTOR: George M. Ponczek

1004 N. Harding Avenue Chicago, 111., V.St.A.

Daniel C. Stahly 312 Myrtle Avenue Elmhurst, 111., V.St.A.

909881/0704

r -

The invention relates to a motor control circuit.

The invention relates generally to control loops for motors and, more particularly, to an improved motor control circuit for smaller household appliances and the like.

In the field of control loops for motors, there are various types of speed or speed controllers with solid-state components that can be used for improvement the performance of the motor and to achieve certain control properties.

For example, U.S. Patent No. 3,701,935 (inventor A.A. Collie) discloses a solid state regulator circuit for a Motor described in which a centrifugal switch with two contacts in the trigger or control circuit a TRIAC circuit breaker is used for to trigger the latter selectively and thus the rotational speed of the motor when opening and closing to regulate the centrifugal switch contacts depending on the changes in the engine speed. To this So it is not necessary that the contacts of the centrifugal switch have to carry the full current for the motor.

Modifications of this type of control circuit are disclosed in U.S. Patent 3,317,807 (inventor J. Dorner et al.) And in U.S. Pat

909881/0704

OBlGlNAL INSPECTED

U.S. Patent 3,223,911 (inventor E.F. Seiler et al.) Is illustrated. The aforementioned US Pat. No. 3,317,807 describes a capacitively operating one Coupling system to the centrifugal switch to Switch off slip ring connections. The aforementioned US Pat. No. 3,223,911 describes the control circuit in the trigger circuits different combinations of switch components.

Although the above-mentioned control circuits for motors in general for their intended use and the intended area of application are quite suitable, it is still desirable to provide a motor controller circuit are at which reduces the problems caused by jerky run of the M _o tors at low engine speeds , and this circuit results in a more uniform, more stable mode of operation than could previously be achieved with the above-described, previously known control circuits for motors.

It is therefore the object of the invention to provide a new and improved one Motor control circuit for controlling a wide range of motor rotation speeds in a more stable manner Way without dancing and jerking, i.e. to create uneven running of the motor, this regulator circuit is particularly intended in smaller household appliances that have a speed sensor, such as a Centrifugal switch or governor, and a circuit breaker use find, are used, it should

9Q9881 / 074H

the circuit breaker selectively connects the motor to the power supply terminals.

The proposed to achieve the stated object, the invention M _o torreglerschaltung is characterized in that it comprises a power switch having a control electrode, which is connected in series with a power supply terminal and said to be controlled motor for the selective intrusion of the engine to the power supply terminals that a by the rotational speed controlled and coupled to this device responsive to the motor to selectively, in a predetermined manner, form a first control current path, which when the speed of the motor changes from an adjustable, predetermined speed, and the first control current path with the control electrode of the circuit breaker can be connected, and that switching means are provided which form a second control current path to the control electrode of the circuit breaker independently of the device responding to the rotational speed.

According to the invention, an impedance element is provided in the control circuit of the circuit breaker in order to the second control current path and a predetermined power level independent of switching contacts of a The centrifugal switch located in the first control current path

909881/0704

to accomplish. This second, independent control current path gives a predetermined voltage to be applied and thus a predetermined current conduction angle for the motor at each half-wave in the waveform of the power supply, when the mentioned switch contacts are open. Thus there is a first and a second, independent control current path created to ensure a uniform, stable control and operation of the engine, to avoid Problems caused by jerky or uneven running at low rotational speeds. The changes of the voltage supplied to the motor are compared to the strict on / off operation or the two-point control modified that previously in the control circuit through the switch contacts of the centrifugal switch alone was formed.

According to a feature of the invention, it is a matter of arranging impedance elements in a motor control circuit for a smaller household appliance with a speed sensor device and a power switch in the trigger circuit of the latter in order to deliver a first, predetermined basic power level to the motor when a contact set of the speed sensor device is open, as well as a second predetermined power level, if this K _o are closed ntakte.

Thus, according to the invention, it becomes a motor regulator circuit

909881/0704

For a household appliance or the like. Created in which a speed sensor is used. The speed sensor is in an arrangement according to the invention a centrifugal switch that can be operated by centrifugal force with a switching contact arrangement that is inserted into the trigger or control circuit of a circuit breaker, such as of a TRIAO circuit breaker, switched on is to selectively connect the motor of the household appliance to the power supply connections. The switch contacts of the speed sensor open and close, when the speed of rotation of the Motor with respect to the predetermined rotational speed to which the speed sensor, for example as a centrifugal switch. The household appliance can also be equipped with a device for presetting the speed provided leg which controls a presettable centrifugal switch assembly. In this case, the switch contacts open or close when the speed increases or decreases compared to the speed selected on the device for presetting the speed. The independent one Control current path is parallel to the switch contacts of the centrifugal switch in the trigger circuit of the Circuit breaker for delivering the predetermined power level to the motor when the switch contacts are open Centrifugal switch created.

909881/0704

Structure and mode of operation of the subject matter of the invention, together with further advantages and features, follow from the following description of exemplary embodiments and with reference to the accompanying single drawing, which shows a Shows a circuit diagram of a motor regulator circuit according to the invention.

Referring to the accompanying drawing, the motor controller circuit according to the invention shown in connection with a motor 10 for alternating current. The runner circle 12 of the motor 10 is in series with an excitation winding 14, two power supply connections at 16 and 18, and the main current path of a circuit breaker component, such as a TRIAC circuit breaker at 20, switched. The power supply connections 16, 18 are more suitable for connection to an AC power source Voltage, such as a 110 V / 60 Hz network provided. The motor control circuit according to the invention is used in connection with the control of a motor 10 for alternating current for a household appliance, such as a mixer, explained, even if it goes without saying, that the motor control circuit can be used in other areas, and also as a speed control circuit.

A mechanical centrifugal force switch or other speed sensing device, which is indicated generally at 30 is

909881/0704

connected to the shaft of the motor 10 and rotates with this. In a special embodiment of the invention the centrifugal switch of the same general design as shown in US Pat. No. 2,703,381 (inventor I. Jepson) and is described. This type of centrifugal switch 30 includes a pair of switch contacts at 32, which form a switch that is operated by the rotating, from the Centrifugal-influenced arms of the centrifugal switch assembly is actuated when the speed of the motor 10 exceeds a predetermined speed to which the centrifugal switch 30 has been set. To this Purpose is the centrifugal switch 30 from the adjustable Type associated in association with a speed presetting device, indicated generally at 50 will. It goes without saying, however, that the motor control circuit according to the invention can also be used in such household appliances or the like. Where no speed presetting is used.

According to one embodiment, the speed adjusting device comprises 50 an adjustment button that is used to determine the operating speed of the household appliance is rotated by adjusting the centrifugal switch 30. The setting for centrifugal switch 30 is caused by displacement of a first contact arm with respect to a second, movable contact arm, which of different arms influenced by centrifugal force or

909881/0704

Structuring is controllable. In short, as the rotational speed of the motor 10 increases, the movable one moves Contact arm away from the first contact arm. According to the characteristics of the mechanical parts of the centrifugal switch 30 and according to the speed presetting at 50 opens the switch contact pair 32 at a predetermined Speed. If, in a corresponding manner, the rotational speed falls below the predetermined rotational speed falls, the switch contact pair 32 is closed by the fact that the first and second contact arms with each other contact. So when the speed adjuster 50 is set to settings for various Speeds within the operating speed range of the household appliance is rotated, the by centrifugal force operated centrifugal switch 30 brought to the switch contact pair 32 at different corresponding rotational speeds of the motor 10 to open and close. The control circuit of the motor 10 is also in series with power supply terminals 16 and 18 with an on / off switch (not shown) fitted. In an alternative embodiment, the speed adjuster 50 includes one On / off switch in series with the power source at 19 for controlling the operating state of said motor regulator circuit a.

According to an important feature of the invention is an

909881

At

Conclusion of the switch contact pair 32 to the rotor circuit 12 and connected to the TRIAC circuit breaker 20. The other connection of the switch contact pair 32 is to the control electrode 60 of the TRIAC circuit breaker 20 Via a series connection of a variable resistor 62, a phase shift resistor 64 · and an opposing sense polarized parallel diode pair connected at 68.

So if the switch contact pair 32 is closed, the control electrode 60 brings the TRIAO circuit breaker 20 in the conductive or switched-through state at a predetermined starting point or ignition angle for each half-wave the waveform of the alternating voltage from the power source 19 as this point of entry through the impedance elements of the control loop is set. A phase shift capacitor 70 is connected to the power supply terminal and the connection point between the variable resistor 62 and the phase shift resistor 64-connected. In a particular embodiment, yet another phase delay capacitor 72 is connected to the Power supply connection 18 and to the connection point between the phase shift resistor 64 · and the opposite direction polarized diode pair 68 connected. In a special embodiment, there is also a bleeder resistor 73 is connected between the control electrode 60 and the power supply connection 18.

So after this one special embodiment of the invention, the switch contact pair is closed at 32, so the impedance elements 62, 64, 70 and 72 control it Conducting or the firing angle of the TRIAC circuit breaker 20 to create a predetermined current flow angle and for the output of an effective voltage value each half-wave of the waveform of the current source 19.

According to another important feature of the invention is parallel to the switch contact pair 32 of the centrifugal switch 30 created a second, independent control current path through an impedance branch, which at its one End connected to the junction between the variable resistor 62 and the phase shift resistor 64- is, and at its other end to the connection point between the rotor circuit 12 and the TRIAC circuit breaker 20. This parallel-connected impedance branch closes a variable resistor 82 and, according to a special embodiment, a fixed resistor 84 · connected in series with the latter. In the open state of the switch contact pair 32 is a predetermined, minimum power value, the one corresponds to a relatively small current conduction angle and a low applied voltage at each half-wave, supplied to the engine 10. When the switch contact pair 32 is responsive to the variations in rotational speed of the motor 10 at low speed preset

position of the centrifugal switch J5Ö opens and closes, so the value of the supplied power and the current conduction angle change with each half cycle between the values, which are specified by the two control current paths and their respective impedance elements.

Thus, the characteristic values of the control circuit for the motor 10 are compared to the on / off mode of operation or two-point control that is controlled by a centrifugal switch alone, without the independent, second control current path with the variable Resistor 82 and the fixed resistor 84 · modified. Conventional uneven running problems at low operating speeds, as observed in household appliances that have a large operating speed range or a Bringing a high operating speed ratio into use are also eliminated because the at every half-wave and at open contact of the centrifugal switch 30 supplied Voltage is maintained at a predetermined value to maintain operation at that speed.

For this purpose, the variable resistor 82 is adjusted such that a power value is output to the those required power in the idle state (no load) corresponding to in which the lowest desired operating speed is not exceeded, or slightly below this value. In a special embodiment it was found that the ignition voltage to

909861/10704

Fulfillment of this requirement was around 50 V. Thus becomes with the open switch contact pair 32 the predetermined Basic power level output in order to reduce problems caused by jerky circulation, i.e. uneven running at low speeds and also to a more desired on / off duration or switching cycle of the switch contact pair 32 of the To achieve centrifugal switch 30.

Albeit illustrating various aspects of the invention and have been described, it will be understood that various changes and modifications may be made to those skilled in the art can come up with. Therefore, it is intended that the appended claims cover all such changes and modifications as they fall within the principle and scope of the invention.

For example, according to another embodiment, the variable resistor 62 can be a fixed resistor with the connection point between the rotor circle 12 and the TRIAC circuit breaker 20 be connected. The switch contact pair 32 is at one end at the connection point between this fixed resistor and the variable Resistor 62, and at its other end to the connection point connected between the power source 19 and the TRIAC circuit breaker 20. Then the switch contact pair 32 arranged such that opens below the adjustable, predetermined speed and above it closes.

909S81 / Q704

Blank page

Claims (2)

1 2. G. 79 Claims {1. jMotor control circuit, characterized in that that it comprises a circuit breaker (20) with a control electrode (60) in series with a power supply connection (18) and the motor to be controlled (10) for the selective connection of the motor (10) to the Power supply connections (16, 18) is switched; that one controlled by the speed of rotation and on this responsive device (30, 50) is coupled to the motor (10) to selectively, in predetermined Way, when changing the speed of the motor (10) compared to an adjustable, predetermined Speed to form a first control current path (32, 62, 64, 68, 70, 72, 73), and the first control current path can be connected to the control electrode (60) of the circuit breaker (20); and 909881/0704 . ₂ . 2123894 - That circuit means (82, 8 * 0 are provided, the a second control current path independently of the device (30, 50) responsive to the rotational speed to form the control electrode (60) of the circuit breaker (20). 2. Motor control circuit according to claim 1, characterized in that the power switch (20) one in the phase controlled trigger circuit comprises, and that the independent, second control current path forming circuit means Impedance elements (82, 84) which, when the the first control current path (32) is opened via the device (30, 50) responsive to the rotational speed, for Control of the trigger circuit and to create a complete control of the motor (10) are used. 3. Motor control circuit according to claim 2, characterized in that the responsive to the rotational speed Device is a centrifugal switch (30) with a first contact arm, which is in its position accordingly the rotational speed of the motor (10) is adjustable, as well as with a second contact arm, which is adjacent to the first contact arm is arranged, is provided, and that the two contact arms to create the first control current path form a pair of switch contacts (32). 909881/0704 J ». Motor control circuit according to Claim 3, characterized in that in that they also have a speed adjustment device (50) for controlling the speed of rotation responsive device (30) and for selecting the predetermined speed. 5. Motor control circuit according to claim 3 and U , characterized in that the second contact arm is adjustable with respect to the first contact arm by the setting device (50) for the speed. 6. Motor control circuit according to claim 1, characterized in that the independent, second control current path creating circuit means for outputting a predetermined power value to the motor (10) accordingly the operating conditions for the minimum operating speed include variable resistor (82). 7. Motor control circuit according to claim 1 and 6, characterized in that the power supply connections (16, 18) an alternating current source (19) is applied, and that the predetermined power value is a predetermined proportion of each half-wave of the waveform of the alternating current source (19). 909881/0704 . ή. 2S23894 8. Motor control circuit according to claim 1, characterized in that the circuit means for creating an independent, second control current path include a variable resistor (82), and that the Power supply terminal (18) is connected to an AC power source (19), and the variable resistor (82) for controlling the circuit breaker (20) can be set in such a way that it is at a predetermined Voltage value at each half-wave of the waveform of the alternating current source (19) becomes conductive. 9. Motor control circuit according to claim 1, characterized in that the circuit means for creating of the independent, second control current path for outputting a power for the operation of the motor (10) first impedance element (82) of a predetermined value serving for low rotational speed. 10. Motor control circuit according to claim 9, characterized in that that the first impedance element (82) for delivering said power for operating the motor (10) is adjustable in its value at low rotational speed when the first control current path is open. 909881/0704 11. Motor control circuit according to claim 10, characterized in that said second control current path ^{comprises a second impedance element (8 1} O balanced in its value) that is set such that the circuit breaker (20) becomes conductive at a predetermined voltage value. 12. Motor control circuit according to claim 2, characterized in that the power switch (20) by a TRIAC circuit breaker formed and the trigger circuit with the control electrode (60) of the TRIAC circuit breaker (20) is connected. 13. Motor control circuit according to claim 12, characterized in that that the trigger circuit comprises two oppositely polarized, parallel diodes (68), which is connected between the control electrode (60) and the control output for the TRIAC circuit breaker (20) are, and that a phase shift capacitor (72) between the control output and one side of the connection (18) the power source (19) is switched. lA. Motor control circuit according to Claim 1, characterized in that that the first control current path can be established when the speed of the motor (10) 909881/0704 -S- is below the adjustable, predetermined rotational speed, and that the first control current path can then be separated when the rotational speed of the motor (10) is above the adjustable, predetermined Rotation speed is. 909881/0704