JP2010088553A - Cloth presser lifting device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the fixed state of the height of a cloth presser at the electric power cut off. <P>SOLUTION: The cloth presser lifting device includes: an air cylinder 4 for lifting the cloth presser 5; a first electromagnetic valve 10 feeding air pressure from an air pressure source 20 to respective air chambers 4U and 4D of the air cylinder; an operation input means 30 for operating the cloth presser; a control means 40 for switching the height of the cloth presser by controlling the first electromagnetic valve and stopping the cloth presser on the way according to the length of the lowering time; preliminary exhaust pathways 71 and 72 disposed in the respective air chambers of the cylinder; check valves 73a disposed in the respective preliminary exhaust pathways; a closing pressure feeding pathway 74 for feeding air pressure to the respective check valves; a second electromagnetic valve 75 switchable an air pressure feeding state or an atmospheric air releasing state to the exhaust side of the respective check valves; and a presser releasing control circuit 77 for switching the state of the second electromagnetic valve to the air pressure feeding state when the electricity is carried from a main power supply or to the state of releasing to the atmosphere when the main power supply is cut off. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a cloth presser lifting and lowering device for a sewing machine that lifts and lowers a cloth presser using an air cylinder.

Some sewing machines are provided with a cloth presser lifting / lowering device that presses down a cloth to be sewn. This cloth presser lifting and lowering device can be moved up and down between a lower position where the cloth presser presses the cloth and an upper position where the presser of the cloth is released from above the cloth placed on the sewing machine bed. For raising and lowering the cloth presser, for example, by using an air cylinder having a three-position type electromagnetic valve as a drive source, by moving the piston back and forth by the control of the electromagnetic valve, the cloth presser is moved upward and downward. It stops at the intermediate position between the lower position where it is most lowered and its upper position and lower position (see, for example, Patent Document 1).
Here, the height of the intermediate position of the cloth presser is determined by the set time of the cloth presser lowering operation stored in the ROM of the control device. That is, when moving to the intermediate position, air pressure is supplied to the air chamber on the ascending side of the air cylinder in a period shorter than the arrival time from the upper position to the lower position, so that it can be stopped halfway.
JP 2001-87584 A

However, the conventional cloth presser lifting / lowering apparatus has a problem that when the main power supply of the sewing machine is cut, the cloth presser is fixed at a height immediately before cutting.
As a result, for example, when the cloth presser is fixed at the lower position, it cannot be pulled out if any pinching of the cloth occurs, and the air cock on the air pressure supply source side is closed and the air tube serving as the intake / exhaust path is removed. Had to be released.
In addition, when the cloth presser is fixed at the upper position or the intermediate position, especially when an intermediate presser interlocking with the sewing needle is provided, the cloth presser interferes and the sewing needle cannot be lowered to the bottom. In this case, the air cock on the air pressure supply source side must be closed and the air tube serving as the intake / exhaust path must be removed to release the pressure.

  An object of the present invention is to avoid pinching by a cloth presser when the power is shut off.

  According to the first aspect of the present invention, there is provided a cloth presser for holding the cloth, a support mechanism for supporting the cloth presser so that the cloth presser can be moved up and down, an air cylinder serving as a lift driving source for the cloth presser, and a pressure presser for the air cylinder from an air pressure supply source. The rising position where the lowering air chamber is open to the atmosphere while the air pressure to the rising air chamber is being supplied, and the air pressure to the lowering air chamber while the rising air chamber is open to the atmosphere A first solenoid valve that can be switched between a lowered position to be supplied and a neutral position that prevents gas flow to both air chambers; an operation input means that performs an operation to raise and lower the cloth presser; The first solenoid valve is controlled in accordance with an operation from an operation input means, and the cloth presser is switched to any one of an upper position, an intermediate position, and a lower position, and the height to the intermediate position is set to the electromagnetic valve. To the lowered position A sewing machine cloth presser lifting and lowering device including a control means that adjusts by setting a length of time during which the lifting is performed separately from the intake / exhaust path for position switching control between the upper position, the intermediate position, and the lower position A preliminary exhaust path provided for each of the air chambers on the lower side and the descending side, a check valve that allows only exhaust from each of the air chambers provided for each of the preliminary exhaust paths, and A blocking pressure supply path for supplying air pressure to the exhaust side of the check valve, and provided in the blocking pressure supply path, the air pressure supply state for the exhaust side of each check valve and the air release state for the exhaust side can be switched. The second solenoid valve and the second solenoid valve are provided with a press release control circuit that switches to a pneumatic supply state when the main power of the sewing machine is energized and switches to an atmospheric release state when the main power is cut off. To.

  The invention according to claim 2 has the same configuration as that of the invention according to claim 1, and a speed control valve capable of manual flow rate adjustment having a check valve is used as each check valve. .

In the invention according to claim 1, since the cloth presser can be stopped at the intermediate position, the cloth presser can be brought close to or temporarily held with the sewing product, and more appropriate when the sewing product is set. It becomes possible to arrange in the position.
Furthermore, since the operation to stop the cloth presser at the intermediate position is performed by setting the air pressure supply time to the air cylinder, it is possible to perform software processing without adding a new configuration such as a unique member for performing the intermediate stop. This can be realized, and it becomes possible to improve productivity by reducing costs.
In addition, since the operation to stop the cloth presser at the intermediate position is performed by setting the air pressure supply time to the air cylinder, it is possible to eliminate the need for flow rate adjustment work by the speed controller, and the height of the intermediate position of the cloth presser Adjustment work can be easily performed.

According to the first aspect of the present invention, when the main power source is connected, the second electromagnetic valve is in a state of supplying air pressure to the exhaust side of each check valve. On the other hand, since the pressure of each air chamber of the air cylinder does not become higher than the supply pressure of the air pressure supply source, the exhaust from each air chamber of the air cylinder through the preliminary exhaust path is blocked. Therefore, there is no influence on the control for switching the upper position, the intermediate position, and the lower position of the cloth presser by the first electromagnetic valve.
On the other hand, when the main power supply of the sewing machine is turned off, the second solenoid valve is switched to the atmospheric release state by the press release control circuit, so that each check valve allows exhaust from each air chamber of the air cylinder. For this reason, even when the cloth presser is positioned at any height, it is possible to easily move the cloth presser by applying an external force and to eliminate all the disadvantages of the cloth presser being fixed.

The invention according to claim 2 uses a speed control valve capable of manual flow rate adjustment as each check valve. When such a speed control valve is used, the flow rate is adjusted to 0 by manual adjustment, and the flow in the direction blocked by the check valve is completely stopped.
Since the speed control valve is generally cheaper and easier to obtain than a single check valve, the production cost of the apparatus can be reduced and the productivity can be improved.

(Schematic configuration of the embodiment)
A cloth presser lifting / lowering apparatus 1 according to an embodiment of the present invention will be described in detail. FIG. 1 is a schematic configuration diagram showing a main configuration of a cloth presser lifting / lowering apparatus 1 for a sewing machine.
The cloth presser lifting / lowering device 1 includes a cloth presser 5 that holds a cloth that is a sewing object, a support mechanism 2 that supports the cloth presser 5 so that the cloth presser 5 can be moved up and down, and a cloth presser cylinder 4 as an air cylinder that lifts and lowers the cloth presser 5. The first solenoid valve 10 for switching the air pressure supply state from the pump 20 as the air pressure supply source to the cloth presser cylinder 4 and the operation input means for inputting instructions for raising and lowering the cloth presser 5 and starting the sewing. The operation pedal 30, the cloth pressing cylinder 4, the first electromagnetic valve 10 and the control device 40 as a control means connected to the operation pedal 30 to drive and control the cloth pressing cylinder 4 and the first electromagnetic valve 10, An operation panel 50 for setting the operation, and a memo as storage means for storing the driving time of the cloth presser cylinder 4 and the first solenoid valve 10 set by the operation panel 50 42, intake / exhaust paths 61, 62, 63 for controlling the position of the cloth presser 5, and the air chambers on the rising side and the lowering side of the cloth pressing cylinder 4 separately from the intake / exhaust paths 61, 62, 63. Preliminary exhaust paths 71 and 72 provided for 4U and 4D, speed control valves 73 and 73 that allow only exhaust from the air chambers 4U and 4D provided for the respective preliminary exhaust paths 71 and 72, and air pressure supply A clogging pressure supply path 74 for supplying air pressure to the exhaust side of each speed control valve 73, 73 from the source, and a pressure supply state for the exhaust side of each speed control valve 73, 73 and the exhaust side The second solenoid valve 75 that can be switched between the open state to the atmosphere and the second solenoid valve 75 is switched to the air supply state when the main power of the sewing machine is energized and switched to the open state when the main power is cut off. Even and a release control circuit 77.
The intake / exhaust passages 61, 62, 63, the preliminary exhaust passages 71, 72, and the closing pressure supply passage 74 are all formed of an air tube.

(Cloth presser and support mechanism)
The cloth presser 5 is supported by the support mechanism 2 on the upper surface of the bed portion 102 of the frame 100 so as to be movable up and down. be able to.
The support mechanism 2 is disposed on the upper surface of the bed portion 102 and has a cloth feed base 2a that supports the cloth presser 5 so as to be slidable up and down. The other end portion is provided with a bell crank 2b that imparts a lifting operation to the cloth presser 11 by rotating. The bell crank 2b is formed in an approximately L shape, and a bent portion thereof is supported at the tip of the cloth feed base 2 so as to be rotatable around a pin 3b provided along the horizontal direction. Then, one end portion of the bell crank 2b is rotated by a movement operation applied in the front-rear direction by the cloth pressing cylinder 4, and an up-and-down operation is applied to the cloth pressing member 5 by moving the other end portion up and down.

(Cloth holding cylinder)
The cloth presser cylinder 4 is supported at one end of the cloth feed base 2 so as to be rotatable about a pin 3a (cylinder fulcrum shaft) provided in the horizontal direction, and on the other end side. The rod 4a is connected to the other end of the bell crank 2b. As a result, the rod 4a of the cloth presser cylinder 4 moves forward and backward to move along an arc trajectory according to the rotation of the other end of the bell crank 2b, thereby allowing vertical displacement. Yes.
Further, the cloth presser cylinder 4 accommodates a piston connected to the rod 4a on the inner side thereof, and is a double-acting type air provided with a lifting air chamber 4U and a lowering air chamber 4D of the cloth presser 5 on both sides of the piston. Cylinder. In the cloth presser cylinder 4, when air pressure is supplied to the ascending air chamber 4 </ b> U, the piston moves backward to give the cloth presser 5 an ascending operation. When air pressure is supplied to the lowering air chamber 4 </ b> D, the piston moves forward and gives the cloth presser 4 a lowering operation.

(First solenoid valve)
The first solenoid valve 10 is a five-port three-position valve, and the first port 11 is connected to the ascending air chamber 4U of the cloth presser cylinder 4 via the intake / exhaust passage 61, and the second port 12 is intake / exhaust. The third port 13 is connected to the pump 20 via the intake / exhaust path 63, and the open ports 14 and 15 are open to the atmosphere without being connected to each other. .
The first solenoid valve 10 is an all-port block type, and closes all the ports 11 to 15 in the neutral position (initial position: valve center), and the first solenoid valve 10 in the raised position (the valve left side) which is the first operation position. The second port 12 and the open port 15 are communicated while the one port 11 and the third port 13 are communicated, and the first port 11 and the open port 14 are communicated at the lowered position (the right side of the valve) which is the second operating position. However, the second port 12 and the third port 13 are communicated.
The first solenoid valve 10 is a pilot type that uses the air pressure from the pump 20 for position switching. The first solenoid valve 10 is normally in a neutral position, and is used for ascending to supply operating pressure for switching from the neutral position to the ascending position. A solenoid 21 and a lowering solenoid 22 for supplying an operating pressure for switching from the neutral position to the lowering position are provided.
These solenoids 21 and 22 are connected to the I / O port 41 of the control device 40. When the signal from the control device 40 is OFF, the first solenoid valve 10 is positioned in the neutral position, and when the signal is ON, the respective solenoids 21 and 22 are operated. Operates to apply supply pressure to the position.
That is, the first solenoid valve 10 is in a neutral position when the signals to both the solenoids 21 and 22 are OFF, and gas flow to both the air chambers 4U and 4D is prevented. Further, when the signal to the raising solenoid 21 is turned on and the signal to the lowering solenoid 22 is turned off, the raising position is reached, and the lowering air chamber 4D is opened to the atmosphere while supplying air pressure to the raising side air chamber 4U of the cloth presser cylinder 4. As shown in FIG. Further, when the signal to the lifting solenoid 21 is turned off and the signal to the lowering solenoid 22 is turned on, the lowering position is reached, and the rising air chamber 4U of the cloth presser cylinder 4 is opened to the atmosphere while the air pressure is applied to the lowering air chamber 4D. And the cloth presser 5 is lowered.

(Operating pedal)
The operation pedal 30 is a triple pedal having three switches 31, 32, and 33. The switch 31 lowers the cloth presser 5 from the upper position by the first input and stops it at the intermediate position. Is a switch for raising the cloth presser 5 by the input of. The switch 32 further lowers the cloth presser 5 when the cloth presser 5 is in the intermediate position. The switch 33 is an activation switch as activation means for activating the sewing machine and sewing the cloth.
Each switch 31, 32, 33 is of a type in which the contact is closed only when it is stepped on by an operator. The operation pedal 30 is connected to the I / O port 41 of the control device 40, and a command signal based on the operation of the operation pedal 30 by the user is transmitted to the control device 40. Based on this command signal, the control device 40 21 and 22 are driven.

(control panel)
The operation panel 50 notifies the user of information related to sewing and is used when setting sewing conditions and the like. The operation panel 50 is configured by a liquid crystal touch panel or the like, and necessary information is displayed on the display unit 51 under the control of the control device 40. Touch panel icons and the like are displayed on the display unit 51, and the user can set sewing conditions and the like by touching these icons. That is, the display unit 51 also functions as the operation unit 52.
The operation panel 50 includes a CPU 53 that handles processing relating to display and operation input. The CPU 53 is connected to the CPU 53 of the control device 40.
The operation panel 50 is configured to be able to set the driving time of the cloth presser cylinder 4 when the cloth presser cylinder 4 is moved up and down by the cloth presser cylinder 4, and the operation panel 50 functions as a drive time setting means.
The operation panel 50 sets a time for preventing the start of the sewing machine by the switch 33 until the cloth presser 5 is stabilized by the control device 40 until the cloth presser 5 is stabilized. It also functions as a setting means.

(Control device)
The control device 40 is also a sewing machine control device that controls the operation of the entire sewing machine, and performs operation control of the first electromagnetic valve 10 in addition to the function of executing sewing control. The control device 40 includes the I / O port 41 described above, a CPU 43, a memory 42 connected to the CPU 43, and a calculation unit 44 serving as a work area for the CPU 43.
Switches 31, 32, and 33 are connected to the input portion of the I / O port 41, and the solenoid 21 for raising and the solenoid 22 for lowering the first electromagnetic valve 10 are connected to the output portion. The memory 42 stores data representing a plurality of needle drop positions that form a stitch pattern in advance. The calculation unit 44 is for controlling the operation of the first electromagnetic valve 10 in accordance with the state of the switches 31, 32, 33 of the operation pedal 30, and is software stored in a ROM (not shown), for example. The software stored in the memory 42 can also be used.

The memory 42 also functions as a storage unit that stores the driving time of the cloth presser cylinder 4 set by the operation panel 50 (described later).
The control device 40 drives the cloth presser cylinder 4 based on the drive time stored in the memory 42 when the operation pedal 30 is operated.
The control device 40 controls the cloth presser cylinder 4 so as to perform an intermediate stop when the cloth presser 5 is lifted and lowers the cloth presser 5 without performing the intermediate stop. In addition, single stroke control (single stroke control means) for controlling the cloth presser cylinder 4 can be performed.
The control device 40 functions as an activation prevention control unit that forcibly cuts off the connection between the switch 33 and the control device 40 for a time set by the operation panel 50.

(Two-stage stroke control)
FIG. 2 is a timing chart of the solenoids 21 and 22 of the first solenoid valve 10 in the two-stage stroke control.
When the two-step stroke control is set, after the main power is turned on, the solenoid 21 is first turned off and the solenoid 22 is turned on when the origins of the solenoids 21 and 22 are searched. Is switched to OFF and the solenoid valve 10 is set to the raised position. As a result, air pressure is supplied to the ascending air chamber 4U of the cloth presser cylinder 4, and the cloth presser 5 is put on standby (S1).
In this initial position, when the switch 31 is depressed for the first time, the solenoid 21 is switched OFF and the solenoid 22 is switched ON, the solenoid valve 10 is set to the lowered position, and air pressure is supplied to the lowered air chamber 4U. Then, the lowering of the cloth presser 5 is started (S2). At this time, the CPU 43 reads the driving time of the cloth presser cylinder 4 stored in the memory 42 and measures the time (S3). When the driving time elapses, the solenoid 21 is turned off and the solenoid 22 is turned off. Is set to the neutral position to stop the cloth presser 5 at the intermediate position corresponding to the driving time (S4).
Next, when the switch 32 is stepped on, the solenoid 22 is turned ON to bring the solenoid valve 10 into the lowered position, the air pressure is supplied to the lowered air chamber 4U, and the presser 5 is lowered to the lower position. (S5). When the switch 31 is depressed at this timing, the solenoid 21 is turned on and the solenoid 22 is turned off, the electromagnetic valve 10 is moved up, the cloth presser 5 is returned to the upper position, and the state of S1 described above is achieved. return.
After stepping on the switch 32, the CPU 43 measures a preset activation waiting time, and during that time, even if the sewing start input is received by the switch 33, the sewing does not start (S6).
Then, after the start waiting time has elapsed, when the switch 33 is depressed, a start command is output to a sewing machine motor (not shown) to start sewing (S7).
When the sewing based on the sewing pattern data is completed and the switch 31 is stepped on, the solenoid 21 is turned on and the solenoid 22 is turned off to return the cloth presser 5 to the upper position with the solenoid valve 10 as the raised position. Return to the same state as S1 described above (S8), and wait until the next sewing.

(Single stroke control)
In the single stroke control, the same control as the two-stroke operation is performed except that the processes of S3, S4, and S5 in the two-stroke operation are not performed. That is, when the switch 31 is stepped down in S2, the CPU 43 waits for the start-up waiting time to elapse and then accepts the stepping of the switch 33 to execute sewing.

(Preliminary exhaust route)
In addition to the intake and exhaust paths 61 and 62 described above, preliminary exhaust paths 71 and 72 for exhausting air from the ascending air chamber 4U and descending air chamber 4D of the cloth presser cylinder 4 are provided. The preliminary exhaust paths 71 and 72 may be directly connected to the air chambers 4U and 4D, respectively, but here, one end thereof is connected so as to branch from the middle of the intake and exhaust paths 61 and 62. Yes.

(Speed control valve)
Speed control valves 73 and 73 are provided at the other end portions of the preliminary exhaust paths 71 and 72, respectively. Further, the speed control valves 73 and 73 are provided with a block pressure supply path 74 that leads to the pump 20 side. Is connected.
Each speed control valve 73 is configured by connecting a check valve 73a and a variable throttle valve 73b in parallel, and the check valve 73a is a direction that allows a flow from the cloth holding cylinder 4 toward the pump 20. Is attached. Further, the variable throttle valve 73b has an adjusting screw for manually adjusting the passage flow rate, and is used in a state where the passage flow rate is always adjusted to zero. That is, the variable throttle valve 73b is used in a state in which the function of controlling the flow rate is abandoned, and each speed control valve 73 is used in the same state as that in which only the check valve 73a is provided.

  On the other hand, the downstream side of the check valve 73a in the air passage direction is connected to the blocking pressure supply path 74, and the blocking pressure supply path 74 is connected to the pump 20 by opening the second electromagnetic valve 75. Therefore, when the second electromagnetic valve 75 is in communication with the pump 20, the air pressure from the pump 20 is applied to the check valve 73a. Since the check valve 73a has a built-in spring that urges the valve body in the direction in which the valve body closes, the check valve 73a is higher than the total pressure of the spring pressure and the air pressure from the pump 20. If no pressure is generated on the upstream side of the check valve 73a (cloth holding cylinder 4 side), air does not flow from the check valve 73a to the downstream side thereof.

(Occlusion pressure supply route)
The blocking pressure supply path 74 forms a Y-shaped pipe composed of a bifurcated pipe connected individually to each of the speed control valves 73 and 73 and a merging pipe that joins them. Is connected to the outlet port 75 b of the second electromagnetic valve 75.

(Second solenoid valve)
The inlet port 75a of the second solenoid valve 75 is connected to the pump 20, and it is possible to switch between supply and stop of air pressure as the back pressure of the valve body of each check valve 73a.
The second solenoid valve 75 is a three-port two-position valve, and is provided with an open port 75c in addition to the aforementioned inlet port 75a and outlet port 75b.
The second solenoid valve 75 communicates the outlet port 75b and the open port 75c at the initial position (the right side of the valve) to release the back pressure of the check valves 73a and 73a to the atmospheric pressure. On the left side, the inlet port 75a and the outlet port 75b are communicated to supply air pressure from the pump 20 as the back pressure of the check valves 73a and 73a.
The second solenoid valve 75 is a pilot type that uses the air pressure from the pump 20 for position switching, and is a natural open type, so that it returns to the initial position when the operation signal is OFF and when the power supply is interrupted. It has become.
Further, the second electromagnetic valve 75 is provided with a solenoid 76 that is normally set to the initial position and supplies an operating pressure for switching from the initial position to the operating position. The solenoid 76 is connected to the press release control circuit 77.

(Presser release control circuit)
The presser release control circuit 77 is provided with a power supply circuit 78 that supplies power to each part of the sewing machine 10. The power supply circuit 78 converts the power supplied from the original main power supply into a direct current suitable for the supply target and converts it into a predetermined voltage to supply power.
The presser release control circuit 77 has a main power cut-off detection circuit 79 that detects the occurrence of a power cut-off state in the power circuit 78. The presser release control circuit 77 outputs an ON signal to the solenoid 76 when the main power supply interruption detection circuit 79 does not detect the power supply interruption of the power supply circuit 78, and the main power supply interruption detection circuit 79 supplies the power supply of the power supply circuit 78. When the shutoff is detected, the operation control to stop the output of the ON signal is performed. As a result, when the main power supply is ON, the second electromagnetic valve 75 can be maintained in the operating position, and the back pressure of the check valves 73a and 73a is increased and the air chambers 4U and 4D of the cloth presser cylinder 4 are spared. Exhaust to the exhaust paths 71 and 72 can be prevented.
On the other hand, when the main power supply is turned off, the main power supply interruption detection circuit 79 detects the power supply interruption of the power supply circuit 78, the ON signal to the solenoid 76 is cut off, and the second electromagnetic valve 75 is returned to the initial position. it can. As a result, the back pressure of the check valves 73a, 73a is released to the atmosphere, and the air can be freely exhausted from the air chambers 4U, 4D of the cloth presser cylinder 4 through the preliminary exhaust passages 71, 72. Therefore, the cloth presser 5 can be moved freely even manually, for example.

(Explanation of operation of sewing machine cloth presser lifting device)
The operation of the cloth presser lifting / lowering apparatus 1 having the above-described configuration will be described. Since the operation by the control device 40 has already been described, the operation based on the presser release control circuit 77 will be described here.
First, when the main power supply of the power supply circuit 78 of the sewing machine is turned on, the main power supply cutoff detection circuit 79 detects this, and the press release control circuit 77 turns on the solenoid 76 of the second electromagnetic valve 75. As a result, the second electromagnetic valve 75 is maintained in the operating position, and air pressure is supplied from the pump 20 to the check valves 73a and 73a, and this is used as a back pressure from the air chambers 4U and 4D of the cloth presser cylinder 4. Exhaust gas that passes through the check valves 73a and 73a is blocked.
Therefore, even if sewing control is executed by the control device 40 in such a state and the air pressure of any one of the air chambers 4U and 4D of the cloth presser cylinder 4 is supplied and the cloth presser 5 is moved up and down, Each configuration from the preliminary exhaust paths 71 and 72 to the pump 20 has no influence on the operation. For example, even if air pressure is supplied to any one of the air chambers 4U and 4D of the cloth holding cylinder 4, the check valves 73a and 73a are all closed by the pump 20 with a back pressure higher than the air pressure. The supply pressure to the cloth presser cylinder 4 does not fall off.
When the main power supply is turned off due to some necessity during sewing or when the sewing is finished, the main power shutoff detection circuit 79 detects this through the power supply circuit 78 and stops outputting the ON signal to the solenoid 76. To do.
As a result, the second electromagnetic valve 75 is returned to the initial position, the back pressure of each check valve 73a, 73a becomes equal to the sum of the atmospheric pressure and the spring pressure of the valve body, and each air chamber of the cloth holding cylinder 4 Since exhaust can be easily performed from 4U and 4D through the check valves 73a and 73a, the cloth presser 5 can be easily moved up and down regardless of the position.

(Effect of embodiment)
As described above, since the cloth presser lifting and lowering device 1 of the sewing machine can stop the cloth presser 5 at the intermediate position, the cloth presser 5 can be brought close to the cloth or temporarily pressed. It becomes possible to arrange at an appropriate position.
Furthermore, since the height of the intermediate position of the cloth presser 5 can be adjusted by setting the air pressure supply time to the cloth presser cylinder 4, it is possible to add a new configuration such as a unique member for performing the intermediate stop. This can be realized by software processing in the control device 40, and it is possible to improve productivity by reducing costs.
In addition, since the operation of stopping the cloth presser 5 at the intermediate position is performed by setting the air pressure supply time to the cloth presser cylinder 4, it becomes possible to eliminate the flow rate adjustment work by the speed controller. Position height adjustment work can be easily performed.

Further, in the cloth presser lifting / lowering device 1 of the sewing machine, when the main power supply is ON, the second electromagnetic valve 75 is in an air pressure supply state to the exhaust side of each check valve 73a, 73a. Exhaust from the air chambers 4U, 4D through the preliminary exhaust paths 71, 72 is blocked. Accordingly, there is no influence on the control for switching the upper position, the intermediate position, and the lower position of the cloth presser by the first electromagnetic valve 10.
On the other hand, when the main power supply of the sewing machine is turned off, the second electromagnetic valve 75 is switched to the atmospheric release state by the press release control circuit 77, so that the check valves 73a and 73a are connected to the air chambers 4U and 4U of the cloth press cylinder 4. Allow exhaust from 4D. For this reason, even when the cloth presser 5 is located at any height, it is possible to easily move the cloth presser by applying an external force and to eliminate all the disadvantages of the cloth presser being fixed.

(Other)
The cloth presser may be divided into two parts and individually moved up and down. In such a case, the cloth presser lifting and lowering device of the sewing machine can be applied.
That is, the same structure as the cloth presser lifting / lowering device 1 of the sewing machine is individually prepared for the two cloth pressers divided into two, and among them, the control device 40, the operation panel 50, the operation pedal 30, and the presser release control circuit 77. The power supply circuit 78 is preferably shared.
And the control apparatus 40 performs operation control with respect to the two first electromagnetic valves 10 so that the cloth pressers 5 and 5 individually move up and down by a predetermined operation for each switch of the operation pedal 30. To do. Further, it is desirable that the press release control circuit 77 controls the two second solenoid valves 75 and 75 in exactly the same manner according to the ON / OFF of the main power supply.
Further, the third port 13 may be connected to the closing pressure supply path 74 via the supply / exhaust path 63.

It is a schematic block diagram which shows the main structures of the sewing machine which is embodiment of invention. It is a time chart which shows the flow of the raising / lowering of the cloth presser by the two-step stroke control in embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cloth presser raising / lowering device 5 Cloth presser 20 Support mechanism 4 Cloth presser cylinder (air cylinder)
4U, 4D Air chamber 10 First solenoid valve 20 Pump (pneumatic supply source)
30 Operation pedal (operation input means)
40 Control device (control means)
61, 62, 63 Intake / exhaust path 71, 72 Preliminary exhaust path 73 Speed control valve 73a Check valve 74 Blocking pressure supply path 75 Second solenoid valve

Claims (2)

A cloth presser holding the cloth,
A support mechanism for supporting the cloth presser so as to be movable up and down;
An air cylinder as a lifting drive source of the cloth presser;
While the air pressure is being supplied from the air pressure supply source to the air chamber on the fabric cylinder raising side of the air cylinder, the lowering air chamber is opened to the atmosphere, and the rising air chamber is opened to the atmosphere. A first solenoid valve that can be switched between a lowered position in which air pressure is supplied to the lower air chamber and a neutral position that prevents gas flow to both air chambers;
Operation input means for performing an operation for raising and lowering the cloth presser;
The first electromagnetic valve is controlled in accordance with an operation from the operation input means to switch the cloth presser to any one of an upper position, an intermediate position, and a lower position, and the height to the intermediate position is set to the electromagnetic position. In a cloth presser lifting and lowering device for a sewing machine comprising control means for adjusting by setting the length of time that the valve is in the lowered position,
In addition to the intake and exhaust paths for position switching control between the upper position, the intermediate position and the lower position, a preliminary exhaust path provided for each of the ascending and descending air chambers;
A check valve that allows only exhaust from each of the air chambers provided for each of the preliminary exhaust paths;
A blocking pressure supply path for supplying air pressure from the air pressure supply source to the exhaust side of each check valve;
A second solenoid valve provided in the blocking pressure supply path and capable of switching between an air pressure supply state to the exhaust side of each check valve and an air release state to the exhaust side;
A cloth presser lifting and lowering device for a sewing machine, comprising: a press release control circuit that switches to a pneumatic pressure supply state when the main power supply of the sewing machine is energized and switches to an atmospheric release state when the main power supply is cut off.   The sewing machine cloth presser lifting and lowering apparatus according to claim 1, wherein a speed control valve capable of manual flow rate adjustment having a check valve is used as each check valve.

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