Knee-controlled motor control device for a motor-driven presser mechanism of a sewing machine

Abstract

A motor control device is used to control an electric motor that drives a presser mechanism of a sewing machine and includes a knee lever mechanism and a control module. The knee lever mechanism includes a switch component, an actuator rotatable to actuate the switch component at a predetermined angular position, and a rotatable knee lever operable by knee contact to rotate and to drive rotation of the actuator. When the control module determines that the switch component is actuated, the control module controls the electric motor to move the presser mechanism to dispose a presser foot of the presser mechanism at a predetermined height relative to a bed of the sewing machine.

What is claimed is: 
     
         1 . A motor control device for controlling operation of an electric motor that drives movement of a presser mechanism of a sewing machine, said motor control device comprising:
 a knee lever mechanism including:
 a switch component, 
 an actuator rotatable to actuate said switch component when rotated to a predetermined angular position, and 
 a rotatable knee lever operable by knee contact to rotate and to drive rotation of said actuator; and 
   a control module coupled to said switch component and to be coupled to the electric motor;   wherein, when said control module determines said switch component to be in an actuated state, said control module is configured to control operation of the electric motor to move the presser mechanism to dispose a presser foot of the presser mechanism at a predetermined height relative to a bed of the sewing machine.   
     
     
         2 . The motor control device as claimed in  claim 1 , wherein said knee lever mechanism further includes a variable resistor component coupled to said control module, spaced apart from said switch component, having a rotary axle portion, and a forced portion that extends from said rotary axle portion and that abuts against said actuator, and having a resistance varying with rotation of said rotary axle portion,
 wherein rotation of said actuator forces said forced portion so as to rotate said rotary axle portion and vary the resistance of said variable resistor component;   wherein further rotation of said actuator to the predetermined angular position results in said actuator actuating said switch component; and   wherein, when said control module determines said switch component to be in a non-actuated state, said control module is configured to control operation of the electric motor to move the presser mechanism according to the resistance of said variable resistor component.   
     
     
         3 . The motor control device as claimed in  claim 2 , wherein said knee lever mechanism further includes an attachment seat, said actuator being mounted rotatably to said attachment seat and having a lever-connecting portion connected to said knee lever for co-rotation with said knee lever relative to said attachment seat, and a driving portion opposite to said lever-connecting portion and abutting against said forced portion of said variable resistor component. 
     
     
         4 . The motor control device as claimed in  claim 3 , wherein said actuator is disposed between said variable resistor component and said switch component, said variable resistor component being disposed adjacent to said driving portion, said switch component being disposed adjacent to said lever-connection portion. 
     
     
         5 . The motor control device as claimed in  claim 4 , wherein said actuator is formed with a protrusion disposed to actuate said switch component when said actuator is rotated to the predetermined angular position. 
     
     
         6 . The motor control device as claimed in  claim 4 , wherein said switch component and said variable resistor component are disposed on said attachment seat. 
     
     
         7 . The motor control device as claimed in  claim 3 , wherein said knee lever mechanism further includes a first spring having opposite ends that are connected to said attachment seat and said actuator, respectively. 
     
     
         8 . The motor control device as claimed in  claim 7 , wherein said variable resistor component further has a protrusion part extending from said rotary axle portion, said knee lever mechanism further including a limiting module that includes:
 a base seat disposed on said attachment seat and adjacent to said rotary axle portion;   a limiting member disposed on said base seat and having an end portion disposed to abut against said rotary axle portion of said variable resistor component when said rotary axle portion is at an initial angular position relative to said base seat; and   a second spring having opposite ends connected to said protrusion part and said base seat, respectively, said second spring biasing said rotary axle portion to the initial angular position.   
     
     
         9 . The motor control device as claimed in  claim 3 , wherein said rotary component further has a protrusion part extending from said rotary axle portion, said knee lever mechanism further including a limiting module that includes:
 a base seat disposed on said attachment seat and adjacent to said rotary axle portion;   a limiting member disposed on said base seat and having an end portion disposed to abut against said rotary axle portion of said variable resistor component when said rotary axle portion is at an initial angular position relative to said base seat; and   a spring having opposite ends connected to said protrusion part and said base seat, respectively, said spring biasing said rotary axle portion to the initial angular position.   
     
     
         10 . The motor control device as claimed in  claim 2 , wherein, when said control module determines said switch component to be in the non-actuated state, said control module is configured to convert a resistance variation of said variable resistor component into a displacement value of the presser foot, and to control operation of the electric motor for moving the presser mechanism according to the displacement value. 
     
     
         11 . The motor control device as claimed in  claim 10 , wherein said control module is a programmable module that is configured with a built-in program to perform conversion of the resistance variation of said variable resistor component into the displacement value of the presser foot. 
     
     
         12 . A presser driving device for driving movement of a presser mechanism of a sewing machine, said presser driving device comprising a knee lever mechanism, a control module coupled to said knee lever mechanism, and an electric motor coupled to said control module and to be coupled to the presser mechanism;
 wherein said knee lever mechanism includes:
 a switch component coupled to said control module, 
 an actuator rotatable to actuate said switch component when rotated to a predetermined angular position, and 
 a rotatable knee lever operable by knee contact to rotate and to drive rotation of said actuator; 
   wherein, when said control module determines said switch component to be in an actuated state, said control module is configured to control operation of said electric motor to move the presser mechanism to dispose a presser foot of the presser mechanism at a predetermined height relative to a bed of the sewing machine.   
     
     
         13 . A sewing machine comprising:
 a bed;   a head disposed above said bed;   a presser mechanism supported by said head and including a presser bar and a presser foot at one end of said presser bar; and   a presser driving device including a knee lever mechanism, a control module coupled to said knee lever mechanism, and an electric motor coupled to said presser mechanism and said control module;   wherein said knee lever mechanism includes:
 a switch component coupled to said control module, 
 an actuator rotatable to actuate said switch component when rotated to a predetermined angular position, and 
 a knee lever mounted for rotation relative to said bed and operated by knee contact to rotate and to drive rotation of said actuator; 
   wherein, when said control module determines said switch component to be in an actuated state, said control module is configured to control operation of said electric motor to move said presser bar to dispose said presser foot at a predetermined height relative to said bed.