TECHNICAL FIELD
[0001] This disclosure relates to a sewing machine.
BACKGROUND DISCUSSION
[0002] As this type of background discussion, a sewing machine shown in
JP 2008-245728A (Reference 1) is known. This sewing machine includes two or more variable resistors
having characteristics in which the relationship between the stepping amount of a
stepping plate provided inside a pedal formed by a foundation and the stepping plate,
and a resistance value varies, and switching means for alternatively switching a variable
resistor to be connected to a control device of the sewing machine out of the two
or more variable resistors. Moreover, link that comes into slidable contact with a
variable resistor, and a tension spring coupled to one end of the link and the other
and of the link are provided. The link is moved upward by the tension spring. Additionally,
a compression spring that biases the stepping plate so as to be kept away from the
foundation is provided inside the pedal. If the stepping plate is stepped on by an
operator, the other end of the link moves, and the resistance value that determines
the rotational frequency of a sewing machine motor changes so that sewing speed can
be controlled.
[0003] Additionally, as the background discussion, a sewing machine shown in Japanese Utility
Model Registration No.
1587171 (Reference 2) is known. This sewing machine is provided with a variable resistor
provided inside a pedal formed by a foundation and a stepping plate, a link that comes
into slidable contact with the variable resistor, and a tension spring coupled to
one end of the link and the other end of the link. The link is moved upward by the
tension spring. Additionally, a compression spring that biases the stepping plate
so as to be kept away from the foundation is provided inside the pedal. If the stepping
plate is stepped on by an operator, the other end of the link moves, and the resistance
value that determines the rotational frequency of a sewing machine motor changes so
that sewing speed can be controlled.
[0004] However, in the sewing machine of Reference 1, since a component force in an oblique
direction is to be generated in a link mechanism that transmits a user's (also including
a seller) foot controller stepping force to the variable resistor, and transmission
efficiency becomes low, there is a problem in that a user's stepping force may become
great and operativity may become poor.
[0005] Additionally, the same problem as the sewing machine of Reference 1 occurs also in
the sewing machine of Reference 2.
EP 0053938 relates to a speed setting arrangement for a sewing machine.
[0006] This disclosure has performed in view of the above problems, and a need thus exists
for a sewing machine that can operate a variable resistor with a high transmission
efficiency.
SUMMARY
[0007] In order to solve the above-described problems, according to a first aspect of this
disclosure, there is provided is a sewing machine including a foot controller in which
a stepping portion is displaceable according to a user's stepping amount; a moving
device that is built in the foot controller and moves according to the displacement
amount of the stepping portion; a variable resistor that is built in the foot controller
and is capable of changing a resistance value according to the movement amount of
the moving device; and a motor that causes to change a sewing speed according to the
resistance value of the variable resistor. The moving device has a first movement
member that is pressed by the stepping portion and moves in a stepping direction of
the foot controller; a rotary body that engages the first movement member, and converts
the movement amount of the first movement member into a rotational amount; and a second
movement member that engages the rotary body, moves in a direction orthogonal to the
movement direction of the first movement member by the movement amount according to
the rotational amount of the rotary body, and changes the resistance value of the
variable resistor according to the movement amount thereof.
[0008] According to the first aspect, the sewing machine of this disclosure is configured
so that the moving device includes the first movement member that moves in the stepping
direction of the foot controller, the rotary body that converts the movement amount
of the first movement member into a rotational amount, and the second movement member
that converts the rotational amount of the rotary body in a direction orthogonal to
the movement direction of the first movement member and moves, and is configured to
change the resistance value of the variable resistor when the second movement member
moves in the direction orthogonal to the movement direction of the first movement
member. Thereby, a component force in an oblique direction is not generated among
the first movement member, the rotary gear, and the second movement member, and the
variable resistor can be operated with a high transmission efficiency.
[0009] Additionally, a second aspect of this disclosure has a configuration in which the
first movement member has a first rack that is pressed by the stepping portion and
moves in the stepping direction of the foot controller, the rotary body has a gear
that engages the first rack and converts the movement amount of the first rack into
a rotational amount, the second movement member has a second rack that engages the
rotary body, and converts the rotational amount of the gear in the direction orthogonal
to the movement direction of the first rack so as to move, and the variable resistor
includes a variable resistor lever that engages a variable resistor lever operating
portion provided at one end of the second rack, moves together with the second rack,
and changes the resistance value of the variable resistor.
[0010] According to the second aspecct, the sewing machine of this disclosure is configured
so that the first movement member has the first rack, the rotary body has the gear
that converts the movement amount of the first rack into a rotational amount, the
second movement member has the second rack that converts the rotational amount of
the gear in the direction orthogonal to the first movement direction and moves, and
the resistance value of variable resistor is changed by the variable resistor lever
of the variable resistor via the variable resistor lever operating portion provided
at one end of the second rack. Thereby, the transmission efficiency of forces among
the first rack, the gear, and the second rack can be further improved, and the variable
resistor can be operated with a high transmission efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing and additional features and characteristics of this disclosure will
become more apparent from the following detailed description considered with the reference
to the accompanying drawings, wherein:
Fig. 1 is a perspective view of a sewing machine of an embodiment disclosed here;
Fig. 2 is an appearance view of the foot controller of the embodiment disclosed here
as viewed from the oblique upward direction;
Fig. 3 is an appearance view of the foot controller of the embodiment disclosed here
as viewed from the oblique downward direction;
Fig. 4 is an explanatory view of the foot controller of the embodiment disclosed here;
Figs. 5A and 5B are structural views of the moving device of the embodiment disclosed
here, and Fig. 5A is a structural view of the overall moving device and Fig. 5B is
a structural view of a movement direction changing mechanism portion in the moving
device;
Figs. 6A and 6B are schematic views of the foot controller of the embodiment disclosed
here, and a graph of the relationship between a stepping amount and load;
Fig. 7 is a cross-sectional view of a foot controller of the background discussion;
Figs. 8A and 8B are explanatory views of the force relationship of the foot controller
of the background discussion, and Fig. 8A is an explanatory view of the stepping power
and load of the foot controller and Fig. 8B is a graph of the relationship between
the stepping amount and load of the foot controller; and
Fig. 9 is an explanatory view for the calculation based on a schematic view of the
foot controller of the background discussion.
DETAILED DESCRIPTION
[0012] An embodiment disclosed here and an embodiment of the background discussion will
be explained with reference to the attached drawings.
Embodiment Disclosed Here
[0013] Fig. 1 is a perspective view of a sewing machine 1 of an embodiment disclosed here.
The sewing machine 1 is placed on a table 8, a foot controller 10 is placed on a floor
surface 9, and the sewing machine 1 and the foot controller 10 are electrically connected
by harness 2. The sewing machine 1 has a motor 6 and a board 5 built therein. The
board 5 is electrically connected to the motor 6 via the harness 2 and an inner wire
7 via a connector 3 (refer to Fig. 2).
[0014] Fig. 2 is an appearance view of the foot controller 10 of the embodiment disclosed
here as viewed from the oblique upward direction. The foot controller 10 includes
a base casing 11 that comes into contact with the floor surface 9, a stepping casing
12 (stepping portion) that is turnably press-fitted to and engaged with the base casing
11 via a turning shaft 11a formed integrally with the base casing 11, and the harness
2 that passes through a first harness through hole 11b formed integrally in the rear
surface of the base casing 11, and electrically transmits a signal generated in the
foot controller 10 to a main body 1. The harness 2 has the connector 3 that electrically
connects the main body 4 and harness 2 of the sewing machine 1 at one end thereof.
The stepping casing 12 has a first harness escape recess 11c having an opening portion
equal to or slightly larger than the first harness through hole 11b at a position
that overlaps the first harness through hole 11b when being stepped.
[0015] In addition, the harness 2 can also be passed through a second harness through hole
11d or a third harness through hole 11f formed integrally in a side surface of the
base casing 11, instead of the first harness through hole 11b. The stepping casing
12 has a second harness escape recess 11e and a third harness escape recess 11g similarly
to the first harness recess 11c so that the harness is not disconnected even if the
position where the harness 2 is taken out from the base casing 11 is changed.
[0016] Fig. 3 is an appearance view of the foot controller 10 of the embodiment disclosed
here as viewed from the oblique downward direction. A harness through groove 11h that
communicates with the first harness through hole 11b, a fourth harness through hole
11i that communicates with the harness through groove 11h, and a harness storage portion
11j that communicates with the fourth harness through hole 11i are formed integrally
with the base casing 11 at the back of the base casing 11 of the foot controller 10.
The harness storage portion 11j is provided with two harness presser guides 11k for
preventing the harness 2 from jumping out of the harness storage portion 11j when
the harness 2 is rounded into a small ring shape and stored in the harness storage
portion 11j when the sewing machine 1 is not used. The harness through groove 11h
is provided with four harness presser guides 11l for preventing the harness 2 from
jumping out of the harness through groove 11h when the harness 2 is inserted therethrough.
[0017] Fig. 4 is an explanatory view of the foot controller 10 of the embodiment disclosed
here. A mount 21 is attached to the back of the inside of the base casing 11, and
a vertical rack 22 (a first movement member or a first rack) is attached into a vertical
rack guide 21 a of the mount 21. The vertical rack 22 is attached so as to become
substantially right-angled to the inner bottom surface of the base casing 11. An upper
portion of the vertical rack 22 is formed so as to have a circular-arc cross-section.
[0018] Figs. 5A and 5B are structural views of the moving device 20 disclosed here. Fig.
5A is a structural view of the overall moving device 20, and Fig. 5B is a structural
view of a movement direction changing mechanism portion 26 in the moving device 20.
The vertical rack 22, a horizontal rack 24 (a second movement member or a second rack),
a gear 23 (rotary body), and a variable resistor 25 are attached to the mount 21,
and form the moving device 20. The vertical rack 22 is attached into the vertical
rack guide 21a via a first mount slide groove 22b, the horizontal rack 24 is attached
into a horizontal rack guide 21 b via a second mount slide groove 24b, the gear 23
is attached into a gear guide 21e via a gear turning shaft 23c (not shown), and the
variable resistor 25 is attached below the horizontal rack 24. A first rack portion
22c of the vertical rack 22 engages a gear 23a of the gear 23. The gear 23a is formed
integrally with a pinion 23b to form the gear 23. The pinion 23b engages a second
rack portion 24a formed integrally with the horizontal rack 24. The horizontal rack
24 integrally forms a variable resistor lever operating portion 24c that operates
a variable resistor lever 25a of the variable resistor 25 on the lower side thereof.
A moving device return spring 22e is engaged between the mount 21 and the vertical
rack 22. Here, in order to set the pushing force of the vertical rack 22 small, the
diameter of the gear 23a is made larger than the diameter of the pinion 23b.
[0019] In addition, as the pushing force of the vertical rack 22 is set small, it is also
possible to make the diameter of the gear 23a smaller than the diameter of the pinion
23b for a user who selects to keep the relationship between a stepping amount and
sewing speed from being keen. Moreover, it is also possible to meet user's demands
by changing the module of the gear 23a and the pinion 23b instead of adjusting the
diameter of the gear 23a and the pinion 23b.
[0020] The operation of the sewing machine of the embodiment disclosed here will be described
below.
[0021] Figs. 6A and 6B are schematic views of the foot controller 10 of the embodiment disclosed
here, and a graph of the relationship between stepping amount and load. The first
rack portion 22c of the vertical rack 22, the gear 23a of the gear 23, the pinion
23b formed integrally with the gear 23, and the second rack portion 24a of the horizontal
rack 24 form the mechanism portion 26. When a user or a worker (hereinafter unified
as a user) steps on the stepping casing 12 with stepping power P, the vertical rack
22 can perform vertical adjustment movement within a range of a movement amount L1.
The horizontal rack 24 can perform right and left adjustment movement within a range
of a movement amount L2 in synchronization with the adjustment movement by the gear
23a. If the user makes the stepping power P to the stepping casing 12 large, the moving
device return spring 22e is compressed and the horizontal rack 24 moves leftward in
the drawing. If the user makes the stepping power P to the stepping casing 12 small,
the moving device return spring 22e is extended and the horizontal rack 24 moves rightward
in the drawing. The variable resistor lever operating portion 24c formed integrally
with the horizontal rack 24 is engaged with the variable resistor lever 25a of the
variable resistor 25, and performs right and left adjustment movement of the variable
resistor lever 25a in accordance with the movement of the horizontal rack 24. The
stepping amount L1 is movable from zero to Lmax. The movement amount of the variable
resistor lever 25a of the variable resistor 25 can be adjusted from zero to L2 according
to the stepping amount L1. The relationship between the stepping power P according
to the stepping amount L1 and a compressive force F applied to the moving device return
spring 22e becomes like the graph of Fig. 6B.
[0022] The effects of the sewing machine of the embodiment disclosed here will be described
below.
[0023] According to first problem solving means, the sewing machine 1 of the embodiment
is configured so that the moving device 20 includes the vertical rack 22 that moves
in the stepping direction of the foot controller 10, the gear 23 that converts the
movement amount L1 of the vertical rack 22 into a rotational amount, and the horizontal
rack 24 that converts the rotational amount of the gear 23 in a direction orthogonal
to the movement direction of the vertical rack 22 and moves by L2, and is configured
to change the resistance value of the variable resistor 25 when the horizontal rack
24 moves in the direction orthogonal to the movement direction of the vertical rack
22. Thereby, a component force in an oblique direction is not generated among the
vertical rack 22, the gear 23, and the horizontal rack 24, and the variable resistor
25 can be operated with a high transmission efficiency. That is, in the foot controller
110 of the background discussion, a maximum stepping force is required by about 3.57
times a compressive force (the setting value of a spring force) Fmax applied to the
moving device return spring 122e (refer to Fig. 9). In contrast, in the foot controller
10 of the embodiment, the maximum stepping force is merely 0.87 times the compressive
force (the setting value of the spring force) Fmax applied to the moving device return
spring 22e so that easy operation can be made. This is based on the following three
reasons. The first reason is that, in the foot controller 10 of the embodiment, meshing
portions of a gear that is involved in the process in which the user's stepping power
P is converted into the compressive force Fmax applied to the moving device return
spring 22e are present in the mechanism portion 26 in only two places between the
vertical rack 22 and the gear 23 and between the gear 23 and the horizontal rack 24.
The second reason is that the conversion efficiency of the meshing portion of each
gear is as high as about 98%. The third reason is that output is amplified to 1.2
times according to the amplification factor of the mechanism portion 26. (Since the
detailed calculation of the stepping force in the foot controller 110 of the background
discussion is described in the description of operation of the background discussion,
refer to that). Moreover, it is also possible to make the stepping load to the user's
stepping amount L1 linear like the graph of Fig. 6B. Thereby, the user easily catches
the correlation between the stepping amount L1 and the sewing speed linearly, and
can operate the sewing machine 1 with a high precision more closely to s natural feeling.
In addition, since most of the mechanism portion 26 of the embodiment can be constituted
from resin parts called polyoxymethylene (POM) with high strength and excellent lubricity,
the user can be provided with cheap products. The foot controller 10 of the embodiment
can be manufactured more cheaply than that of the background discussion in which two
variable resistors, a changeover switch, and an accessory circuit are built. The foot
controller 10 of the embodiment can realize functions equivalent to a multifunctional
sewing machine having a computer built therein, with a configuration that is easier
than that of the background discussion by preparing a plurality of microcomputer control
patterns in combination with the multifunctional sewing machine.
[0024] According to second problem solving means, the sewing machine 1 of the embodiment
is configured so that the moving device 20 includes the vertical rack 22 that moves
in the stepping direction of the foot controller 10, the gear 23 that converts the
movement amount L1 of the vertical rack 22 into a rotational amount, the horizontal
rack 24 that converts the rotational amount of the gear 23 in the direction orthogonal
to the stepping direction of the vertical rack 22 and moves by the movement amount
L2, and the variable resistor lever 25a that changes the resistance value of the variable
resistor 25 when the horizontal rack 24 moves. Thereby, the transmission efficiency
of forces among the vertical rack 22, the gear 23, and the horizontal rack 24 can
be further improved, and the variable resistor 25 can be operated with a high transmission
efficiency.
Additional Item 1
[0025] In the sewing machine 1 of the embodiment, the movement direction of the moving device
20 is changed from the direction orthogonal to the turning shaft 11 a of the stepping
portion of the foot controller 10 to a parallel direction. This is because the size
of the moving device 20 can be reduced as the conversion efficiency of the mechanism
portion 26 is improved. Thereby, it is possible to form the harness storage portion
11j at a position on the turning shaft 11 a side in the direction orthogonal to the
turning shaft 11a of the stepping portion of the foot controller 10. By forming the
harness storage portion 11j, it is possible to round the harness 2 into, for example,
a small ring shape to store the harness to the harness storage portion 11j when the
sewing machine 1 is not used, and organizing of the sewing machine 1 can be made easier.
Embodiment of the Background Discussion
[0026] Fig. 7 is a cross-sectional view of a foot controller 110 of the background discussion.
The foot controller 110 is provided with a base casing 111 (foundation) that comes
into contact with a floor surface 109, a stepping casing 112 (stepping plate) that
is turnably born about a base casing turning shaft 111a (fulcrum shaft E) provided
at one end of the base casing 111, a variable resistor 125 that is provided inside
the foot controller 110 (pedal) formed by the stepping casing 112 and the base casing
111, a front arm 111b (link) that has one end turnably coupled to a mount 121 (link
foundation), a rear arm 111c (link) that has one end turnably coupled to the other
end of the front arm 111b and the other end coming into a slidable contact with a
variable resistor lever 125a of the variable resistor 125, and a moving device return
spring 122e (tension spring) that is coupled to one end of the front arm 111b and
the other end of the rear arm 111c. A coupling portion between the front arm 111b
and the rear arm 111c moves upward as one end of the front arm 111b and the other
end of the rear arm 111c are drawn to each other by the moving device return spring
122e, and is brought into pressure contact with the rear surface of the stepping casing
112 via a roller 111d turnably provided at the coupling portion. Additionally, a second
moving device return spring 122f that biases the stepping casing 112 so as to be kept
away from the base casing 111 on the base casing turning shaft 111a is provided inside
the foot controller 110, and the stepping casing 112 and the base casing 111 are locked
to each other by convex portions provided at tips thereof, respectively, so as to
approach and separate from each other within a predetermined range. Then, if the stepping
casing 112 is stepped on by a user, the other end of the rear arm 111c moves, and
the resistance value that determines the rotational frequency of the sewing machine
motor 6 changes by the variable resistor 125 so that the sewing speed can be controlled.
[0027] The operation of the sewing machine of the background discussion will be described
below.
[0028] Figs. 8A and 8B are explanatory views of the force relationship of the foot controller
of the background discussion. Fig. 8A is an explanatory view of the stepping force
and load of the foot controller and Fig. 8B is a graph of the relationship between
the stepping amount and load of the foot controller. Fig. 9 is an explanatory view
for the calculation based on a schematic view of the foot controller of the background
discussion. If a user steps on the stepping casing 112 and applies stepping power
P to the coupling portion between the front arm 111b and the rear arm 111c, the rear
arm 111c is pushed out backward by a movement amount L4 against the resultant force
F of the moving device return spring 122e and the second moving device return spring
122f. The stepping amount L3 is movable from zero to Lmax. The movement amount of
the variable resistor lever 125a of the variable resistor 125 can be adjusted from
zero to L4 according to the stepping amount L3. If the user makes the stepping power
P to the stepping casing 112 large, the moving device return spring 122e and the second
moving device return spring 122f are compressed and the variable resistor lever 125a
moves leftward in the drawing. If the stepping power P to the stepping casing 112
is made small, the moving device return spring 122e and the second moving device return
spring 122f are extended by the resultant force of the moving device return spring
122e and the second moving device return spring 122f, and the variable resistor lever
125a moves rightward in the drawing. The relationship among the stepping power P,
the resultant force F, and the stepping amount L3 in this case becomes like the graph
of Fig. 8B. That is, in the foot controller 10 of the background discussion, the maximum
stepping force is required to be about 3.57 times the resultant force (the setting
value of a spring force) Fmax of the moving device return spring 122e and the second
moving device return spring 122f. If the frictional resistance force of the sliding
portion is included in this calculation value, it is expected that a force of 4 times
or more the force of the embodiment is required. Additionally, the stepping load to
the user's stepping amount L3 increases abruptly from a certain point like the graph.
[0029] Here, a calculation example of the graph of Fig. 8B will be described. In Fig. 9,
it is assumed that A=20 mm is established and Θ1 changes within a range from 50 °
to 5°.
[0032] The principles, preferred embodiment and mode of operation of the present invention
have been described in the foregoing specification. However, the invention which is
intended to be protected is not to be construed as limited to the particular embodiments
disclosed. Further, the embodiments described herein are to be regarded as illustrative
rather than restrictive.
[FIG. 1]
UP
RIGHT
FRONT
DOWN
LEFT
REAR
[FIG. 2]
UP
LEFT
REAR
DOWN
RIGHT
FRONT
[FIG. 3]
RIGHT
REAR
DOWN
LEFT
FRONT
UP
[FIG. 4]
RIGHT
REAR
DOWN
LEFT
FRONT
UP
[FIG. 5A]
UP
REAR
RIGHT
DOWN
FRONT
LEFT
[FIG. 6A]
UP
RIGHT
DOWN
LEFT
[FIG. 6B]
LOAD
STEPPING AMOUNT
[FIG. 7]
UP
REAR
DOWN
FRONT
[FIG. 8B]
LOAD
STEPPING AMOUNT
1. Fußsteuerungseinrichtung (10) für eine Nähmaschine, bei der ein Tretabschnitt (12)
in Übereinstimmung mit einem Tretumfang eines Benutzers verlagerbar ist; mit
einer Bewegungsvorrichtung (20), die in der Fußsteuerungseinrichtung eingebaut ist
und in Übereinstimmung mit dem Verlagerungsumfang des Tretabschnitts bewegbar ist;
einem Regelwiderstand (25), der in der Fußsteuerungseinrichtung eingebaut ist und
imstande ist, einen Widerstandswert in Übereinstimmung mit dem Bewegungsumfang der
Bewegungsvorrichtung zu ändern; und
einem Motor (6), der eine Änderung einer Stichgeschwindigkeit in Übereinstimmung mit
dem Widerstandswert des Regelwiderstands bewirkt;
wobei die Bewegungsvorrichtung (20) umfasst:
ein erstes Bewegungselement, das durch den Tretabschnitt drückbar ist und in einer
Tretrichtung der Fußsteuerungseinrichtung bewegbar ist;
einen Drehkörper, der mit dem ersten Bewegungselement in Eingriff ist und den Bewegungsumfang
des ersten Bewegungselements in einen Drehumfang umwandelt;
die Steuerungseinrichtung ist dadurch gekennzeichnet, dass sie ferner aufweist:
ein zweites Bewegungselement, das mit dem Drehkörper in Eingriff ist, in einer zu
der Bewegungsrichtung des ersten Bewegungselements senkrechten Richtung um den Bewegungsumfang
in Übereinstimmung mit dem Drehumfang des Drehkörpers bewegbar ist, sowie den Widerstandswert
des Regelwiderstands in Übereinstimmung mit seinem Bewegungsumfang ändert;
wobei das erste Bewegungselement eine erste Zahnstange hat, die durch den Tretabschnitt
drückbar ist und in der Tretrichtung der Fußsteuerungseinrichtung bewegbar ist,
der Drehkörper ein Zahnrad hat, das mit der ersten Zahnstange in Eingriff ist und
den Bewegungsumfang der ersten Zahnstange in einen Drehumfang umwandelt,
das zweite Bewegungselement eine zweite Zahnstange hat, die mit dem Drehkörper in
Eingriff ist und die den Drehumfang des Zahnrads in der zu der Bewegungsrichtung der
ersten Zahnstange senkrechten Richtung umwandelt, um bewegbar zu sein, und
wobei der Regelwiderstand einen Regelwiderstandshebel umfasst, der mit einem Regelwiderstandshebelbetätigungsabschnitt
in Eingriff ist, der an einem Ende der zweiten Zahnstange vorgesehen ist, zusammen
mit der zweiten Zahnstange bewegbar ist und den Widerstandswert des Regelwiderstands
ändert.
2. Nähmaschine mit einer Fußsteuerungseinrichtung (10) nach Anspruch 1.