JP2008057473A - Tube pump and liquid injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tube pump capable of reducing pump torque and increasing pump efficiency, and a liquid injection device. <P>SOLUTION: In this tube pump 1, the intermediate part 36 of a discharge tube 27 formed of a flexible material, a pressing member 46 moving while sequentially pressing the intermediate part 36 of the discharge tube 27 from the upstream side to the downstream side when a pumping action is performed, and a pump wheel 32 are contained in a housing 31. The pump wheel 32 has cam surfaces C brought into slidable contact with each other when moving between a pump acting position at which the pressing member 46 presses the discharge tube 27 and a pump non-acting position at which the pressing member almost presses the discharge tube 27. On the cam surfaces C, the frictional resistance of a shaft slidable contact portion N with which the pressing member is brought into slidable contact when the pressing member 46 is set at the pump acting position is lower than the frictional resistance of the other portions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer and a tube pump mounted on the liquid ejecting apparatus.

  An ink jet printer (hereinafter simply referred to as “printer”) is one of liquid ejecting apparatuses that eject liquid onto a target from nozzles formed in a liquid ejecting head. In this printer, since the nozzles are opened on the nozzle forming surface of the recording head (liquid ejecting head), the ink viscosity may increase due to evaporation of the ink solvent from the nozzles, and ink ejection failure may occur. For this reason, such a printer is usually provided with a head maintenance mechanism.

  This head maintenance mechanism includes a cap capable of sealing the nozzle formation surface of the recording head and a suction pump provided in an ink discharge passage communicating with the inside of the cap, and generates negative pressure in the cap by driving the suction pump. As a result, the ink having increased viscosity is sucked from the nozzles, and the ejection failure of the ink is suppressed. As such a suction pump, a tube pump as described in Patent Document 1 is usually used.

  The tube pump of Patent Document 1 is a pump that rotates around a longitudinal middle portion of a flexible tube and an axis of the housing in a housing (pump frame in Patent Document 1) having a substantially cylindrical shape. A foil (rotating body) and a roller (pressing member) capable of pressing the tube while moving along the inner peripheral surface of the housing when the pump foil rotates in a predetermined direction are accommodated.

  The tube is accommodated (α-shaped) so that the middle part in the longitudinal direction draws a circle over one round (360 degrees) along the inner circumferential surface of the housing. That is, the tube is disposed in the housing so that the upstream portion and the downstream portion in the intermediate portion thereof are partially overlapped in the axial direction of the housing. Further, the pump wheel is formed with a roller support groove along the circumferential direction, and the roller support groove has a radial distance from the axis of the pump wheel in the circumferential direction from one (pump operating position) to the other (pump operating position). It is formed in a shape that gradually becomes shorter toward the pump non-operating position. And the shaft (in patent document 1, roller shaft) extended so that the roller might protrude from the shaft center is inserted in the roller support groove | channel of a pump wheel so that sliding is possible.

  Therefore, when the pump wheel rotates in the pump action direction, the roller shaft slides and rotates on the groove wall (cam surface) in the roller support groove toward the pump action position on the tube side. At the pump operating position, the roller presses the tube until the inner surfaces of the tubes are completely in contact with each other, so that the roller sequentially presses a part of the intermediate portion of the tube in cooperation with the inner peripheral surface of the housing. However, it moves along the inner peripheral surface of the housing. As the roller moves, the pressed portion of the tube is restored in sequence, so that the inside of the tube upstream of the intermediate portion housed in the housing is depressurized and the inside of the cap is in a negative pressure state. Ink with increased viscosity is sucked from the nozzle.

On the other hand, when the pump wheel rotates in the non-acting direction of the pump, the roller is positioned at the other side of the roller support groove (pump non-acting position). In this state, the tube is slightly pressed by the roller, but even if the roller rotates together with the pump foil, the pressure at this time is such that the inside of the tube is not depressurized due to the restoration of the tube. Even if it rotates in the action direction, the inside of the cap is not sucked and does not become negative pressure, and ink is not sucked from the nozzle.
Japanese Patent Laid-Open No. 2002-349452

  By the way, when the tube pump performs the suction operation, the roller shaft rotates while sliding on the cam surface in a state of receiving the reaction force from the tube crushed at the pump operation position. If it is large, the cam surface is likely to be worn, and it will be a load of pump rotation. Here, the frictional resistance between the roller shaft and the cam surface at the pump operating position is desirably as low as possible from the viewpoint of reducing pump torque and improving pump efficiency.

  However, for example, when the frictional resistance with the roller shaft at the pump operating position is reduced by changing the material of the pump wheel to a low friction material, the pump non-operating position and the pump non-operating position to the pump operating position are reduced. Since the frictional resistance is also reduced, there is a problem that the roller may idle at the pump non-operating position and may not move to the pump operating position.

  And in the tube pump of patent document 1, the countermeasure for reducing the frictional resistance of the shaft of a roller in a pump action position and the groove wall (cam surface) in a roller support groove | channel is not taken especially. For this reason, there is a problem that it is difficult to reduce pump torque and improve pump efficiency.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the invention is to provide a tube pump and a liquid ejecting apparatus capable of reducing pump torque and improving pump efficiency.

  In order to achieve the above object, a tube pump according to the present invention is provided in a housing with an intermediate portion in the longitudinal direction of a tube made of a flexible material and an intermediate portion of the tube sequentially from the upstream side to the downstream side when the pump is operated. A pressing member that generates a negative pressure by moving while pressing, a pumping position that presses the tube so that the pressing member generates a negative pressure, and a non-pump that presses the tube to the extent that no negative pressure is generated. In a tube pump that houses a rotating body having a cam surface that is in sliding contact with the operating position, the frictional resistance on the cam surface is partially changed.

  According to the present invention, the frictional force on the cam surface is partially changed in accordance with the specifications of the tube pump, so that the pressing member suitably presses the tube, or between the pump action position and the pump non-action position. And move smoothly between them. For this reason, it is possible to reduce pump torque and improve pump efficiency.

  In the tube pump of the present invention, when the pressing member is located at the pumping position on the cam surface, the frictional resistance of the portion where the pressing member slides is lower than the frictional resistance of other portions.

  According to the present invention, since the sliding resistance between the pressing member and the cam surface when the pressing member presses the tube is reduced, the wear of the cam surface is reduced and the load during driving of the tube pump is reduced. Is done. For this reason, it is possible to reduce pump torque and improve pump efficiency.

  In the tube pump of the present invention, on the cam surface, a portion where the pressing member slides when the pressing member is located at the pump acting position is made of a low friction material having a lower frictional resistance than other portions.

According to this invention, it becomes possible to reliably reduce the sliding resistance between the pressing member and the cam surface when the pressing member presses the tube.
In the tube pump of the present invention, on the cam surface, a portion where the pressing member slides when the pressing member is located at the pump action position is constituted by a low friction member having a separate structure.

According to this invention, when the pressing member presses the tube, the sliding resistance between the pressing member and the cam surface can be reliably reduced with a simple configuration.
In the tube pump of the present invention, a low-friction paint that reduces frictional resistance is applied to a portion of the cam surface where the pressing member slides when the pressing member is located at the pump action position.

According to this invention, it is possible to easily and reliably reduce the sliding resistance between the pressing member and the cam surface when the pressing member presses the tube.
The liquid ejecting apparatus of the present invention includes a liquid ejecting head that ejects liquid from a nozzle formed on a nozzle forming surface, a cap that can seal the nozzle forming surface, and a suction unit that can suck the inside of the cap. In the liquid ejecting apparatus, the suction means is constituted by the tube pump having the above-described configuration.

  According to the present invention, the pressing member partially changes the frictional resistance on the cam surface so as to suitably press the tube or smoothly move between the pump acting position and the pump non-acting position. Thus, it is possible to reduce pump torque and improve pump efficiency. Therefore, the tube pump can efficiently and stably suck the inside of the cap.

  Hereinafter, an embodiment in which the present invention is embodied in a tube pump mounted on an ink jet printer as a liquid ejecting apparatus will be described with reference to the drawings. In the following description, when referring to “front-rear direction”, “vertical direction”, and “left-right direction”, unless otherwise specified, “front-rear direction”, “vertical direction”, It shall be the same as the “left-right direction”.

  As shown in FIG. 1, an ink jet printer 11 as a liquid ejecting apparatus includes a frame 12 having a substantially rectangular box shape. A platen 13 is installed in the lower part of the frame 12 along the left-right direction which is the longitudinal direction thereof. On the platen 13, the recording paper P is fed from the rear side by a paper feeding mechanism (not shown) based on driving of a paper feeding motor 14 provided at the lower back of the frame 12.

  A guide shaft 15 is installed above the platen 13 in the frame 12 along the longitudinal direction of the platen 13. A carriage 16 is supported on the guide shaft 15 so as to be capable of reciprocating along the axial direction (left-right direction) of the guide shaft 15. That is, the carriage 16 is supported so as to be reciprocally movable along the longitudinal direction of the guide shaft 15 by inserting the guide shaft 15 through a support hole 16a formed penetrating in the left-right direction.

  A driving pulley 17a and a driven pulley 17b are rotatably supported at positions corresponding to both ends of the guide shaft 15 on the inner surface of the rear wall of the frame 12. An output shaft of a carriage motor 18 serving as a driving source for reciprocating the carriage 16 is connected to the drive pulley 17a, and an endless timing connected to the carriage 16 is connected between the pair of pulleys 17a and 17b. A belt 17 is hung. Accordingly, the carriage 16 is movable in the left-right direction via the endless timing belt 17 by the driving force of the carriage motor 18 while being guided by the guide shaft 15.

  A recording head 19 as a liquid ejecting head is provided on the lower surface side of the carriage 16, and an ink cartridge 20 for supplying ink as liquid to the recording head 19 is detachably mounted on the carriage 16. Yes. The ink in the ink cartridge 20 is supplied from the ink cartridge 20 to the recording head 19 by driving a piezoelectric element 21 (see FIG. 2) provided in the recording head 19, and a plurality of inks provided in the recording head 19 are provided. Nozzle 22 (see FIG. 2) is jetted onto the recording paper P fed onto the platen 13 for printing.

  A maintenance mechanism 23 for performing maintenance such as cleaning of the recording head 19 at the time of non-printing is provided in a home position area (non-printing area) that does not correspond to the recording paper P located at the right end in the frame 12. Yes.

Next, the maintenance mechanism 23 will be described in detail.
As shown in FIG. 2, the maintenance mechanism 23 includes a cap 24 having a bottomed square box shape, and an elevating device 25 for elevating the cap 24. The maintenance mechanism 23 raises the cap 24 by the lifting device 25 in a state where the carriage 16 is moved to the home position region, so that the nozzle forming surface 19 a (each nozzle 22) of the recording head 19 is moved by the cap 24. It is designed to be sealed. A protrusion 26 protrudes downward from the bottom wall of the cap 24, and a discharge passage 26 a for discharging ink from the cap 24 is formed in the protrusion 26 so as to penetrate vertically. Has been.

  A base end side (upstream side) of a discharge tube 27 as a tube made of a flexible material is connected to the protrusion 26, and the other end side (downstream side) of the discharge tube 27 has a rectangular parallelepiped shape. It is inserted into the waste ink tank 28. Further, a tube pump 29 as a suction unit for sucking the inside of the cap 24 from the cap 24 side toward the waste ink tank 28 side is provided at an intermediate portion of the discharge tube 27 between the cap 24 and the waste ink tank 28. It is arranged.

  Then, by driving the tube pump 29 in a state where the nozzle forming surface 19a (each nozzle 22) of the recording head 19 is sealed by the cap 24, the ink thickened from each nozzle 22 is sucked together with bubbles and the like, and the cap 24 In addition, so-called cleaning, in which the ink is discharged into the waste ink tank 28 via the discharge tube 27, is performed. The waste ink tank 28 contains a waste ink absorbing material 30 that absorbs and holds the ink discharged into the waste ink tank 28.

Next, the tube pump 29 will be described in detail.
As shown in FIGS. 3 and 4, the tube pump 29 includes a bottomed cylindrical housing 31 fixed in the frame 12 (see FIG. 1). In the center of the bottom wall of the housing 31, a through hole 31 a that penetrates the inside and outside of the housing 31 is formed. A pump wheel 32 as a rotating body is accommodated in the housing 31 so as to be rotatable about an axis A passing through the center of the housing 31. That is, the pump wheel 32 includes a wheel shaft 33 that extends along the axis A and is inserted into the through hole 31 a, and is rotatable within the housing 31 about the wheel shaft 33.

  An upstream opening recess 34 and a downstream opening recess 35 that are opposed to each other in the tangential direction of the inner peripheral surface 31 b of the housing 31 in plan view are formed on the peripheral wall of the housing 31. In this case, the upstream opening recess 34 and the downstream opening recess 35 are displaced in the axis A direction. In the housing 31, the intermediate portion 36 in the longitudinal direction of the discharge tube 27 draws a circle along the inner peripheral surface 31 b of the housing 31 via the upstream opening recess 34 and the downstream opening recess 35. Contained in a routed state.

  In this case, in the intermediate portion 36 of the discharge tube 27 accommodated in the housing 31, the upstream portion 36a and the downstream portion 36b of the intermediate portion 36 are partially overlapped in the direction of the axis A, and these upstream portions The portion where the side portion 36a and the downstream portion 36b are partially polymerized is referred to as a tube polymerization portion B. In this embodiment, the routing of the intermediate portion 36 of the discharge tube 27 in the housing 31 is set to 360 degrees at which the tube overlap portion B is minimized.

  In the upstream portion 36 a and the downstream portion 36 b of the discharge tube 27 in the tube overlap portion B, the thickness of the discharge tube 27 is made thinner than other portions of the intermediate portion 36 of the discharge tube 27 in the housing 31. A thin portion 37 is provided. In this case, the thickness of the thin portion 37 is determined so that the tube overlapping portion B (for two tubes) is easily bent in the housing 31 while the other portion (for one tube) in the intermediate portion 36 of the discharge tube 27 is easily bent. It is set to approach.

  As shown in FIG. 5, on the inner peripheral surface 31b of the housing 31, the upstream portion 36a and the downstream portion are located at positions corresponding to the upstream portion 36a and the downstream portion 36b of the discharge tube 27 in the tube overlap portion B. An upstream recess 38 serving as an upstream escape portion and a downstream recess 39 serving as a downstream escape portion constituting a relief portion that can accommodate 36b are provided. In this case, the upstream recess 38 and the downstream recess 39 are arranged adjacent to each other so as to be continuous along the circumferential direction of the inner peripheral surface 31b of the housing 31 in plan view.

  As shown in FIG. 6, the pump foil 32 includes a large plate 40 having a disk shape and a small plate 41 having a smaller diameter than the large plate 40. The large plate 40 and the small plate 41 are formed of a foil. The shafts 33 are fixed to the wheel shafts 33 at predetermined intervals in a state where the shafts 33 are penetrated. The large plate 40 is formed with a roller guide groove 42 having a circular arc shape that bulges outward. The roller guide groove 42 extends so that one end is located on the outer peripheral side of the large plate 40 and the other end is located on the inner peripheral side of the large plate 40. That is, the roller guide groove 42 gradually extends away from the outer peripheral portion of the large plate 40 from one end to the other end.

  A roller guide recess 43 is cut out at the peripheral edge of the small plate 41 so as to correspond to the roller guide groove 42 of the large plate 40. The inner peripheral surface of the large plate 40 in the roller guide groove 42 of the large plate 40 and the inner surface of the roller guide recess 43 of the small plate 41 are cam surfaces C. A roller 44 as a main body is slidably inserted and supported through a shaft 45 in the roller guide groove 42. That is, the roller 44 slides on the cam surface C via the shaft 45 slidably contacting the cam surface C at both ends. In the present embodiment, the pressing member 46 is configured by the roller 44 and the shaft 45.

  As shown in FIG. 7, the pressing member 46 includes a roller 44 and a shaft 45 that are separate components. That is, a shaft insertion hole 44a is formed through the roller 44 along the axial direction, and a shaft 45 longer than the axial length of the roller 44 is inserted into the shaft insertion hole 44a. The pressing member 46 is configured. Therefore, the shaft 45 is inserted into the shaft insertion hole 44 a of the roller 44 so that both ends in the longitudinal direction protrude from the shaft center of the roller 44. In this case, the roller 44 and the shaft 45 are rotatable relative to each other.

  As a material constituting the shaft 45 of the pressing member 46, a material having a lower frictional resistance than that of the roller 44 is used, and specifically, a metal or a synthetic resin having a low friction property is used. Examples of the synthetic resin having low friction include those of sliding grade such as polyacetal (POM) and polystyrene (PS). In the present embodiment, sliding grade polyacetal is used as the material constituting the shaft 45 of the pressing member 46. Therefore, the pressing member 46 has a lower frictional resistance on the shaft 45 than on the roller 44.

  Retaining pins 47 serving as retaining means for preventing the shaft 45 from being removed from the shaft insertion hole 44 a of the roller 44 are respectively attached to positions on both sides of the shaft 45 across the roller 44. . The retaining pin 47 does not prevent relative rotation between the roller 44 and the shaft 45.

  When the pump motor (not shown) is driven and the pump wheel 32 is rotated in the pump action direction (the arrow direction in FIG. 5), the pressing member 46 is on one end side of the roller guide groove 42 (the outer peripheral side of the pump wheel 32). ; Moves to the pump action position). By this movement, the pressing member 46 rotates and moves while being crushed (pressed) sequentially from the upstream side to the downstream side along the longitudinal direction of the discharge tube 27 along the longitudinal direction of the discharge tube 27.

  Due to the rotational movement of the pressing member 46, the inside of the discharge tube 27 upstream of the tube pump 29 is decompressed. The air and ink inside the cap 24 sealing each nozzle 22 (nozzle forming surface 19a) are gradually discharged toward the waste ink tank 28 by the rotation of the pump foil 32 in the pump action direction. As a result, a negative pressure is generated in the cap 24.

  On the other hand, when the pump wheel 32 is rotated in the pump non-operation direction (the direction opposite to the arrow direction in FIG. 5) opposite to the pump operation direction, the pressing member 46 is moved to the other end side of the roller guide groove 42 (of the pump wheel 32). Move to the center side (pump non-operation position). By this movement, the pressing member 46 is lightly pressed against the intermediate portion 36 of the discharge tube 27, and the reduced pressure state inside the discharge tube 27 is eliminated. That is, when the pump wheel 32 is rotated in the non-acting direction of the pump, the inside of the discharge tube 27 upstream from the tube pump 29 is not depressurized and is not pressed to the extent that no negative pressure is generated in the cap 24. The member 46 presses the intermediate portion 36 of the discharge tube 27.

  Further, as shown in FIG. 6, when the pressing member 46 moves to one end side of the roller guide groove 42 (the outer peripheral side of the pump wheel 32; the pump operating position) on the cam surface C of the pump wheel 32, the pressing member 46 The shaft sliding contact portion N with which the shaft 45 of 46 is slidably contacted is made of a low friction material having a lower frictional resistance than other portions. In this embodiment, polytetrafluoroethylene (PTFE) is used for this low friction material.

Next, the operation of the tube pump 29 will be described.
When cleaning the recording head 19, first, each nozzle 22 (nozzle forming surface 19 a) of the recording head 19 is sealed with a cap 24. In this state, when a pump motor (not shown) is driven and the pump wheel 32 is rotated in the pump action direction, the roller 44 squeezes the intermediate portion 36 of the discharge tube 27 from the upstream side to the downstream side sequentially. Rotate around 45. At this time, both ends of the shaft 45 slide and rotate at a shaft sliding contact portion N on the cam surface C of the pump wheel 32, and an intermediate portion thereof slides and rotates at the shaft insertion hole 44 a of the roller 44.

  In this case, the shaft sliding contact portion N on the cam surface C is made of polytetrafluoroethylene (low friction material), and the shaft 45 is made of sliding grade polyacetal (synthetic resin having low friction). Therefore, the frictional resistance between the shaft 45 and the cam surface C and the frictional resistance between the shaft 45 and the roller 44 are reduced.

  Further, when the roller 44 presses the tube overlapping portion B, the upstream portion 36a and the downstream portion 36b of the discharge tube 27 in the tube overlapping portion B escape from pressing by the roller 44 at different timings. It moves to the upstream recessed part 38 and the downstream recessed part 39, respectively. In addition, due to the action of the thin wall portion 37 provided in the tube overlap portion B, the ease of bending of the tube overlap portion B in the housing 31 is reduced to other portions in the intermediate portion 36 of the discharge tube 27 (portions other than the tube overlap portion B). ), The fluctuation of the pump torque when the tube overlap portion B is pressed by the roller 44 is suppressed.

  Subsequently, when the roller 44 rotates and moves while sequentially crushing the intermediate portion 36 of the discharge tube 27 from the upstream side to the downstream side, the inside of the discharge tube 27 upstream of the tube pump 29 is depressurized, and the inside of the cap 24 Negative pressure is generated. By this negative pressure, the air and ink in each nozzle 22 and cap 24 are sucked and discharged into the waste ink tank 28 through the discharge tube 27, whereby the cleaning of the recording head 19 is completed.

As described above, according to the embodiment described in detail, the following effects can be obtained.
(1) The pressing member 46 uses sliding grade polyacetal as a material constituting the shaft 45 so that the shaft 45 has a lower frictional resistance than the roller 44. For this reason, the frictional resistance between the shaft 45 and the cam surface C is reduced, and the force required to rotate the pump wheel 32 during the pump action is reduced. Therefore, since the pump torque can be reduced, the pump motor (not shown) for driving the pump wheel 32 can be reduced in size, and the pump efficiency of the tube pump 29 can be improved.

(2) In the pressing member 46, since the shaft 45 and the roller 44 are separate components, the material of the shaft 45 and the roller 44 can be easily changed according to the specifications of the tube pump 29.
(3) Since the pressing member 46 is configured such that the shaft 45 and the roller 44 are rotatable relative to each other, the frictional resistance between the shaft 45 and the roller 44 is lower than the frictional resistance between the shaft 45 and the cam surface C. By doing so, the roller 44 can be mainly rotated during the pump operation. For this reason, since friction between the shaft 45 and the cam surface C can be suppressed, wear of the shaft 45 and the cam surface C can be suppressed.

  (4) Since the shaft 45 of the pressing member 46 is attached with a retaining pin 47 for preventing the shaft 45 from being removed from the shaft insertion hole 44a of the roller 44, the shaft 45 is removed from the shaft insertion hole 44a. The positional relationship between the shaft 45 and the roller 44 can be maintained.

  (5) On the cam surface C of the pump wheel 32, the shaft sliding contact portion N is made of polytetrafluoroethylene having a lower frictional resistance than the other portions, so that the pressing member 46 is the intermediate portion 36 of the discharge tube 27. The sliding resistance between the shaft 45 and the cam surface C at the time of pressing can be reduced. For this reason, the wear of the cam surface C can be reduced and the load during driving of the tube pump 29 can be reduced, so that the pump torque can be reduced and the pump efficiency can be improved.

  (6) In the intermediate portion 36 of the discharge tube 27, the tube overlap portion B must press the discharge tubes 27 of the two (upstream portion 36 a and downstream portion 36 b) by the pressing member 46. The load required for crushing becomes larger than the portion. In this respect, according to the present embodiment, since the thin portion 37 is provided in the tube overlap portion B, the tube overlap portion B is more easily bent than the other portions in the intermediate portion 36 of the discharge tube 27. For this reason, the load required for crushing the tube overlap portion B by the pressing member 46 can be reduced with a simple configuration in which the thin portion 37 is provided. Therefore, it is possible to reduce pump torque and improve pump efficiency.

  (7) The discharge tube 27 is set so that the flexibility of the tube overlap portion B approaches the ease of bending of other portions in the intermediate portion 36 of the discharge tube 27 accommodated in the housing 31. That is, in the discharge tube 27, the load necessary for crushing the tube overlap portion B by the pressing member 46 causes the intermediate portion 36 of the discharge tube 27 other than the tube overlap portion in the housing 31 to be crushed by the pressing member 46. It is set to approach the load required for For this reason, the load necessary for crushing the intermediate portion 36 of the discharge tube 27 in the housing 31 is made to be uniform over the entire circumference of the intermediate portion 36 of the discharge tube 27 in the housing 31 including the tube overlap portion B. be able to. Therefore, fluctuations in pump torque can be suppressed, and the tube pump 29 can be driven stably.

  (8) In the intermediate portion 36 of the discharge tube 27 in the housing 31, the tube overlapping portion B must press the discharge tubes 27 corresponding to two (upstream portion 36 a and downstream portion 36 b) by the pressing member 46. Therefore, the load required for crushing becomes larger than other parts. In this regard, according to the present embodiment, the upstream recess 38 and the downstream recess 39 are formed in the housing 31 so as to correspond to the upstream side portion 36a and the downstream side portion 36b that are superposed in the tube overlap portion B, respectively. ing. For this reason, when the tube overlapping portion B is pressed by the pressing member 46, the upstream side portion 36a and the downstream side portion 36b sequentially move to the upstream concave portion 38 and the downstream concave portion 39, respectively, so as to escape from the pressing by the pressing member 46. To do. Therefore, since the load required for crushing the tube overlap portion B by the pressing member 46 can be effectively reduced, the pump torque can be reduced and the pump efficiency can be improved.

(9) Since the upstream recess 38 and the downstream recess 39 are formed in the housing 31 so as to continue along the inner peripheral surface 31 b of the housing 31, the intermediate portion 36 of the discharge tube 27 in the housing 31. Can be set to 360 degrees at which the tube polymerization portion B is minimized. For this reason, at the time of the pump operation, the load when crushing the intermediate portion 36 of the discharge tube 27 by the pressing member 46 is suppressed to almost zero while the amount of leak is suppressed to substantially zero. The load necessary for crushing the tube 27 can be set. Therefore, it is possible to reduce pump torque and improve pump efficiency.
(Example of change)
In addition, you may change the said embodiment as follows.

  By configuring the upstream portion 36 a and the downstream portion 36 b that are polymerized in the tube overlapping portion B with a material having a lower hardness than other portions in the intermediate portion 36 of the discharge tube 27 accommodated in the housing 31, the tube A low hardness portion may be provided in the polymerization portion B. In this way, since the tube overlap portion B is more easily bent than the other portions in the intermediate portion 36 of the discharge tube 27, the load necessary for crushing the tube overlap portion B by the pressing member 46 is reliably reduced. be able to.

  -You may make it change the frictional resistance in the cam surface C of the pump foil 32 partially according to the specification of the tube pump 29. FIG. If it does in this way, the press member 46 can press the discharge tube 27 suitably, or can move smoothly between a pump action position and a pump non-action position. As a result, the pump torque can be reduced and the pump efficiency can be improved. Therefore, when cleaning the recording head 19, the inside of the cap 24 can be efficiently and stably sucked by the tube pump 29.

  The pump wheel 32 may be configured such that the shaft sliding contact portion N on the cam surface C is a low friction member made of polytetrafluoroethylene having a separate structure, or a sliding grade polyacetal or polystyrene. In this case, the low friction member is attached to the pump wheel 32 as a molded product by fitting or the like. In this way, the sliding resistance between the shaft 45 and the shaft sliding contact portion N on the cam surface C when the pressing member 46 presses the intermediate portion 36 of the discharge tube 27 can be reliably reduced with a simple configuration. it can.

  The pump wheel 32 may apply a low friction paint such as polytetrafluoroethylene or grease that reduces frictional resistance to the shaft sliding contact portion N on the cam surface C. In this way, the sliding resistance between the shaft 45 and the shaft sliding contact portion N on the cam surface C when the pressing member 46 presses the intermediate portion 36 of the discharge tube 27 can be easily and reliably reduced. .

The pump wheel 32 may reduce the frictional resistance of the shaft sliding contact portion N by subjecting the shaft sliding contact portion N on the cam surface C to surface processing such as polishing.
In place of the retaining pin 47, an O-ring or the like may be used as retaining means.

The pressing member 46 may be configured such that the shaft 45 is fitted into the shaft insertion hole 44 a of the roller 44 so that the roller 44 and the shaft 45 rotate integrally.
The shaft 45 of the pressing member 46 may be made of a low friction material such as polytetrafluoroethylene.

  The shaft 45 of the pressing member 46 may be formed of only a portion (both ends) in sliding contact with the cam surface C by using a low friction material such as polytetrafluoroethylene, metal, or sliding grade polyacetal or polystyrene.

The pressing member 46 may integrally form the roller 44 and the shaft 45.
-In the housing 31, the upstream recessed part 38 and the downstream recessed part 39 do not necessarily need to be arrange | positioned so that it may adjoin continuously along the internal peripheral surface 31b of this housing 31. FIG.

In the housing 31, any one of the upstream recess 38 and the downstream recess 39 may be omitted.
As the pressing member 46, a sliding member that slides while pressing on the intermediate portion 36 of the discharge tube 27 may be used instead of the roller 44 and the shaft 45.

  In the above embodiment, the liquid ejecting apparatus on which the tube pump 29 is mounted is embodied as the ink jet printer 11. However, the liquid ejecting apparatus is used for manufacturing a color filter such as a liquid crystal display or pixel formation such as an organic EL display. A liquid ejecting apparatus may be used. Alternatively, the tube pump 29 may be mounted on an apparatus other than the liquid ejecting apparatus.

1 is a perspective view of an ink jet printer according to an embodiment. The principal part simplified sectional drawing of FIG. The perspective view of the tube pump of an embodiment. The disassembled perspective view of the tube pump of embodiment. The plane sectional view of the tube pump of an embodiment. In embodiment, the exploded perspective view at the time of assembling a press member to a pump foil. The side view of the press member of embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Inkjet printer as a liquid ejecting apparatus, 19 ... Recording head as a liquid ejecting head, 19a ... Nozzle formation surface, 22 ... Nozzle, 24 ... Cap, 27 ... Discharge tube as tube, 29 ... Tube as suction means Pump, 31 ... housing, 31b ... inner peripheral surface of housing, 32 ... pump foil as rotating body, 36 ... middle part of discharge tube, 36a ... upstream part, 36b ... downstream part, 37 ... thin part, 38 ... An upstream recess as an upstream escape portion constituting the escape portion, 39 ... a downstream recess as a downstream escape portion constituting the escape portion, 44 ... a roller as a main body, 44a ... a shaft insertion hole, 45 ... a shaft, 46 ... pressure Numeral 47, retaining pin as retaining means, A, axis passing through the center of the housing, B, tube overlap portion, C, cam surface.

Claims (6)

An intermediate portion in the longitudinal direction of the tube made of a flexible material in the housing, and a pressing member that generates a negative pressure by moving while pressing the intermediate portion of the tube from the upstream side to the downstream side at the time of pumping. A cam surface that is slidably contacted when moving between a pump operating position that presses the tube so that the pressing member generates negative pressure and a pump non-operating position that presses the tube to the extent that no negative pressure is generated. In a tube pump containing a rotating body provided with,
A tube pump characterized in that frictional resistance on the cam surface is partially changed. 2. The cam surface according to claim 1, wherein when the pressing member is located at the pumping position, a frictional resistance of a portion where the pressing member slides is lower than a frictional resistance of another portion. Tube pump as described in. 2. The low-friction material having a lower frictional resistance than the other part of the cam surface, wherein the part where the pressing member slides when the pressing member is located at the pumping position The tube pump according to claim 2. 3. The cam surface according to claim 1, wherein a portion of the cam surface that is in sliding contact with the pressing member when the pressing member is located at the pumping position is constituted by a separate low-friction member. Tube pump as described in. 3. A low friction paint for reducing frictional resistance is applied to a portion of the cam surface where the pressing member is slidably contacted when the pressing member is located at the pump action position. Tube pump as described in. In a liquid ejecting apparatus including a liquid ejecting head that ejects liquid from a nozzle formed on a nozzle forming surface, a cap that can seal the nozzle forming surface, and a suction unit that can suck the inside of the cap.
A liquid ejecting apparatus comprising the tube pump according to claim 1.

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