Patent Application
20140373765
1. Field of the Invention
The invention relates to a motor control device for a sewing machine, and more particularly to a knee-controlled motor control device for a motor-driven presser mechanism of a sewing machine.
2. Description of the Related Art
The conventional knee-controlled presser driving device 1 of the sewing machine 10 has the following drawbacks:
1. The movement of the presser foot 11 is driven through the cord component 15, and the movement precision of the presser foot 11 may be affected by physical property variation of the cord component 15, such as extension or shrinkage of the cord component 15 that may cause displacement differences between the two ends of the cord component 15 during rotation of the driving portion 132 of the knee lever connector 13, and that results in adverse effect on movement precision of the presser foot 11.
2. Installation and routing of the rope component 15 must be carefully considered, so as to ensure that the driving portion 132 of the knee lever connector 13 can smoothly drive the cord component 15, and thereby ensure proper movement of the presser foot 11.
In view of the above drawbacks, it has been proposed heretofore to use an electric motor for driving movement of the presser foot 11 of the presser mechanism instead of the cord component 15. In addition, the sewing machine usually has a separate mechanism to move and position the presser foot at a predetermined height for facilitating user's operation.
U.S. Pat. No. 8,161,897 discloses a sewing machine which uses a knee lever mechanism with a potentiometer to control operation of an electric motor that drives vertical movement of a presser foot. However, this patent does not disclose a mechanism for automatic movement of the presser foot to a predetermined height using the knee lever mechanism thereof.
Therefore, an object of the present invention is to provide a motor control device that is adapted for controlling an electric motor that drives movement of a presser mechanism of a sewing machine, and that is operable to dispose a presser foot of the presser mechanism at a predetermined height.
According to one aspect of the present invention, there is provided a motor control device for controlling operation of an electric motor that drives movement of a presser mechanism of a sewing machine. The motor control device comprises:
a knee lever mechanism including:
a control module coupled to the switch component and to be coupled to the electric motor.
When the control module determines the switch component to be in an actuated state, the 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.
Another object of the present invention is to provide a presser driving device for driving movement of a presser mechanism of a sewing machine.
According to another aspect of the present invention, a presser driving device comprises a knee lever mechanism, a control module coupled to the knee lever mechanism, and an electric motor coupled to the control module and to be coupled to the presser mechanism.
The knee lever mechanism includes:
When the control module determines the switch component to be in an actuated state, the 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.
Yet another object of the present invention is to provide a sewing machine that comprises:
a bed;
a head disposed above the bed;
a presser mechanism supported by the head and including a presser bar and a presser foot at one end of the presser bar; and
a presser driving device including a knee lever mechanism, a control module coupled to the knee lever mechanism, and an electric motor coupled to the presser mechanism and the control module.
The knee lever mechanism includes:
When the control module determines the switch component to be in an actuated state, the control module is configured to control operation of the electric motor to move the presser bar to dispose the presser foot at a predetermined height relative to the bed.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
Referring to
Referring to
The knee lever 32 is mounted for rotation relative to the bed 100 and is operated by knee contact to rotate.
The actuator 33 is mounted rotatably to the attachment seat 31 and has a lever-connecting portion 331 connected to the knee lever 32 for co-rotation with the knee lever 32 relative to the attachment seat 31, and a driving portion 332 opposite to the lever-connecting portion 331. The actuator 33 is disposed between the switch component 35 and the variable resistor component 34 with the lever-connecting portion 331 disposed adjacent to the switch component 35 and the driving portion 332 disposed adjacent to the variable resistor component 34. The actuator 33 is formed with a protrusion 333 disposed to actuate the switch component 35 when the actuator 33 is rotated to a predetermined angular position.
The variable resistor component 34 has a rotary axle portion 341, a forced portion 342 that extends from the rotary axle portion 341 and that abuts against the driving portion 332 of the actuator 33, and a protrusion part 343 extending from the rotary axle portion 341 in a direction opposite to the forced portion 342, and has a resistance varying with rotation of the rotary axle portion 341. Referring to
The first spring 36 has opposite ends that are connected to the attachment seat 31 and the actuator 33, respectively, so as to provide a resilient force to stabilize rotation of the actuator 33.
The limiting module 4 includes a base seat 41, a limiting member 42, and a second spring 43.
The base seat 41 is disposed on the attachment seat 31 and adjacent to the rotary axle portion 341. The limiting member 42 is disposed on the base seat 41 and has an end portion disposed to abut against an edge of the rotary axle portion 341 of the variable resistor component 34 when the rotary axle portion 341 is at an initial angular position relative to the base seat 41, as shown in
The second spring 43 has opposite ends connected to the protrusion part 343 and the base seat 41, respectively. The second spring 43 provides a resilient force to bias the rotary axle portion 341 to the initial angular position.
Referring to
To sum up, the motor control device of this invention uses the knee lever 32 to vary resistance of the variable resistor component 34, so as to control the electric motor 20 to drive movement of the presser foot 2. Through the switch component 35 and the protrusion 333, the presser foot 2 may be disposed at the predetermined height using the knee lever 32.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
