Sealing member for providing sealing between valving element and valve seat of pressure damper for reducing pressure of liquid supplied from liquid storage means to liquid injection head in liquid injection device, and liquid injection device equipped with pressure damper including same

Abstract

The present invention provides a sealing member capable of providing suitable sealing of a valve in a pressure damper.　A sealing member 124 provides sealing between a valving element 121 and a valve seat 123 and between the valving element 121 and a side wall 111a of a first liquid chamber in a valve of a pressure damper for reducing the pressure of a liquid supplied from a liquid storage means to a liquid injection head in a liquid injection device. The sealing member 124 comprises: an outer peripheral part 124a that presses the side wall 111a of the first liquid chamber in which the valving element 121 is accommodated with a pressure equal to or higher than a prescribed pressure when the sealing member 124 is attached to the pressure damper; and an inner peripheral part 124b that is pressed by the valving element 121 and pressed against the valve seat 123 in a valve closing operation. The sealing member 124 is configured to bend when the inner peripheral part 124b is pressed by the valving element 121 in the valve closing operation, with a restoring force that does not make the pressure received by the inner peripheral part 124b from the valve seat 123 when the valving element 121 is at a closed position less than the prescribed pressure.

Description

A sealing member for sealing the space between the valve body and valve seat of a pressure damper that reduces the pressure of the liquid supplied from a liquid storage means to a liquid injection head in a liquid injection device, and a liquid injection device equipped with a pressure damper including the sealing member.

[0001] The present invention relates to a sealing member for sealing the space between the valve body and valve seat of a pressure damper that reduces the pressure of the liquid supplied from a liquid storage means to a liquid injection head in a liquid injection device, and to a liquid injection device equipped with a pressure damper including the sealing member.

[0002] Conventionally, in liquid ejection devices such as inkjet printers, when liquid is pumped from a liquid storage means such as an ink cartridge or ink tank to a liquid ejection head such as an inkjet head via a liquid supply passage, it is known to install a pressure damper in the liquid supply passage to reduce the pressure before supplying the liquid pumped at high pressure from the liquid storage means to the liquid ejection head. For example, Reference Document 1 discloses a valve unit that functions as such a pressure damper.

[0003] In conventional pressure dampers, even when the valve body closes the communication hole and prevents liquid from flowing through the communication hole from the first liquid chamber, where liquid is initially supplied from the liquid storage means, to the second liquid chamber, where liquid is supplied to the liquid injection head, liquid may still flow from the first liquid chamber to the second liquid chamber through the back and / or side (i.e., the surface that does not come into contact with the valve body) of the sealing member that seals the space between the valve body and the communication hole.

[0004] For example, a conventional pressure damper 500, as shown in Figure 6, has the same configuration as the pressure damper 100 according to the above embodiment, except that it uses a sealing member 524 instead of the sealing member 124, which has a shape that conforms to the side surface, bottom, and valve seat of the first liquid chamber. However, due to manufacturing precision issues, if the outer diameter of the sealing member 524 is smaller than expected from the inner diameter of the side wall 111a of the first liquid chamber 111, a gap large enough for liquid to flow may be created between the sealing member 524 and the side wall 111a of the first liquid chamber 111. Also, if the outer diameter of the sealing member 524 is larger than expected from the inner diameter of the side wall 111a of the first liquid chamber 111, the entire sealing member 524 may be distorted, causing part or all of the sealing member 524 to lift away from the valve seat 123, creating a gap large enough for liquid to flow between the sealing member 524 and the valve seat 123.

[0005] Furthermore, if liquid continuously flows from the first liquid chamber to the second liquid chamber through the back and / or sides of the sealing member that seals the space between the valve body and the communication hole, deposits contained in the liquid, such as pigment particles contained in paint, will accumulate on the back and / or sides of the sealing member. This widens the gap on the back and / or sides of the sealing member, increasing the amount of liquid leaking out through the gap and significantly impairing the sealing valve function of the pressure damper. As a result, the sealing member needs to be cleaned frequently, increasing maintenance costs.

[0006] Japanese Patent Publication No. 2019-104175

[0007] In view of the above, the present invention aims to provide a sealing member that can perform suitable sealing of a valve in a pressure damper, and a liquid injection device equipped with a pressure damper including the sealing member.

[0008] A sealing member according to a first aspect of the present invention is an annular sealing member that seals the space between the valve body and the valve seat and the space between the valve body and the side wall of the liquid chamber in which the valve body is housed in a valve of a pressure damper that reduces the pressure of the liquid supplied from a liquid storage means to a liquid injection head in a liquid injection device, wherein the sealing member comprises an outer circumferential portion that presses the side wall with a pressure of a predetermined pressure or greater when the sealing member is mounted on the pressure damper, and an inner circumferential portion that is pressed against the valve seat by the valve body during a valve closing operation, and the sealing member is configured to bend when the inner circumferential portion is pressed against the valve body during a valve closing operation, with a restoring force that prevents the pressure received by the inner circumferential portion from the valve seat from falling below the predetermined pressure when the valve body is in the closed position.

[0009] According to the above configuration, when the valve is closed in the pressure damper, the sealing member will come into contact with the side wall of the liquid chamber, the valve body, and the valve seat at a pressure that is expected to provide good liquid-tightness.

[0010] When the valve body is in the closed position, the force acting on the inner circumference from the upper surface of the valve seat may be less than the force acting on the inner circumference from the valve body.

[0011] According to the above configuration, when the valve is closed in the pressure damper, the sealing member will come into contact with the side wall of the liquid chamber, the valve body, and the valve seat at a pressure that is expected to provide good liquid-tightness.

[0012] The valve is opened only when the liquid injection head consumes the liquid at a speed equal to or greater than a certain liquid consumption rate, and when the first operation in which the liquid injection head consumes the liquid at a speed equal to or greater than the liquid consumption rate is being performed, the valve body may be configured to move away from the inner circumference and become non-contact with the inner circumference, and then to return to its original position while maintaining contact between the valve body and the inner circumference when the liquid injection head is performing a second operation in which the liquid injection head consumes the liquid at a speed less than the liquid consumption rate.

[0013] With the above configuration, the valve operation remains stable even when the liquid injection head is performing an operation that consumes a small amount of liquid.

[0014] The force with which the inner circumference is pressed against the valve body when the liquid injection head is performing the second operation may be smaller than the force with which the inner circumference is pressed against the valve body when the valve body is in the closed position.

[0015] With the above configuration, the valve operation remains stable even when the liquid injection head is performing an operation that consumes a small amount of liquid.

[0016] A liquid injection device according to a second aspect of the present invention comprises a pressure damper including a sealing member according to a first aspect of the present invention.

[0017] According to the above configuration, the frequency of cleaning the sealing member can be reduced, thereby suppressing maintenance costs.

[0018] According to the present invention, suitable sealing of the valve can be achieved in a pressure damper.

[0019] Schematic cross-sectional view of a pressure damper according to one embodiment of the present invention. (a) is a cross-sectional view of the pressure damper in the closed state, (b) is an enlarged view of the area around the valve body in the closed state, (c) is a cross-sectional view of the pressure damper in the open state, and (d) is an enlarged view of the area around the valve body in the open state. Perspective view ((a)) and cross-sectional view ((b)) of the sealing member of a pressure damper according to one embodiment of the present invention. Cross-sectional view of the sealing member of a pressure damper according to one embodiment of the present invention. (a) is a cross-sectional view of the sealing member before it is attached to the pressure damper, (b) is a cross-sectional view of the sealing member when it is bent before it is attached to the pressure damper, (c) is a cross-sectional view of the sealing member in the open state after it is attached to the pressure damper, and (d) is a cross-sectional view of the sealing member in the closed state after it is attached to the pressure damper. Schematic cross-sectional view of a pressure damper according to one embodiment of the present invention. (a) is a cross-sectional view of the pressure damper in a loosely sealed state, and (b) is an enlarged view of the area around the valve body in a loosely sealed state. Cross-sectional view of a sealing member according to one modification of the present invention. Cross-sectional view of a sealing member according to one modification of the present invention. (a) shows a cross-sectional view of the sealing member before it is attached to the pressure damper, and (b) shows a cross-sectional view of the sealing member in the closed valve state after it has been attached to the pressure damper. Enlarged view of the vicinity of the sealing member of a conventional pressure damper.

[0020] A pressure damper 100 according to one embodiment of the present invention will be described below with reference to the drawings. The pressure damper 100 is installed on the liquid supply path, particularly immediately before the liquid spray head, in a liquid spray device such as an inkjet printer, in order to reduce the pressure of the liquid that is pumped from a liquid storage means for storing liquid to a liquid spray head for spraying liquid onto a target via the liquid supply path.

[0021] For example, the liquid ejection device is a device that ejects liquid using an inkjet method, and may be, for example, an inkjet printer. In this case, the liquid is ink, the liquid storage means is an ink tank or ink cartridge connected to a pump for pressurizing the ink, and the liquid ejection head is an inkjet head. The liquid ejection head may also be mounted on a carriage for moving the liquid ejection head along the surface of the object to which the liquid is to be ejected, and a pressure damper 100 may also be mounted on this carriage.

[0022] (Configuration of Pressure Damper 100) As shown in Figures 1(a) to 1(d), the pressure damper 100 includes a valve body 110, which contains a first liquid chamber 111 communicating with a liquid storage means, a first liquid passage 112 through which liquid flows from the liquid storage means to the first liquid chamber 111, a second liquid chamber 113 communicating with a liquid injection head, a second liquid passage 114 through which liquid flows from the second liquid chamber 113 to the liquid injection head, and a communication hole 115 connecting the first liquid chamber 111 and the second liquid chamber 113. The valve body 110 may be formed as a single unit or may be constructed by combining multiple members. During operation, the first liquid chamber 111, the second liquid chamber 113, and the communication hole 115 are filled with liquid supplied from the liquid storage means. In the figures, for simplification and visibility, the liquid is not shown and no hatching is applied.

[0023] The first liquid chamber 111 is substantially cylindrical and comprises a side wall 111a, a bottom portion 111b surrounding the communication hole 115, and an opening 111c that opens on the opposite side of the bottom portion 111b. The opening 111c is sealed liquid-tight by a lid 120 that fits onto it. For example, the opening 111c and the lid 120 are formed to fit together by press-fitting or screw-fitting.

[0024] The first liquid chamber 111 houses a disc-shaped valve body 121 that closes the communication hole 115 and a first elastic member 122 that biases the valve body 121 toward the second liquid chamber 113. The first elastic member 122 is, for example, a spring such as a compression coil spring. For example, one end of the first elastic member 122 is fixed to an elastic member fixing part 120a provided on the inner surface of the lid 120 (the surface facing the first liquid chamber 111), and the other end is fixed to an elastic member fixing part 121a provided on the surface of the valve body 121 facing the lid 120. For example, the elastic member fixing part 121a consists of a plurality of arc-shaped walls protruding from the valve body 121 and is slidably held by a cylindrical holding part 120b protruding from the lid 120.

[0025] A valve seat 123 for receiving the valve body 121 is provided on the bottom portion 111b. For example, the valve seat 123 is formed integrally with the bottom portion 111b. An annular sealing member 124 is positioned on the valve seat 123 to seal the space between the valve body 121 and the communication hole 115 when the valve body 121 closes the communication hole 115. In addition, to prevent the sealing member 124 from floating up from the valve seat 123 due to the movement of liquid in the first liquid chamber 111, the sealing member 124 is held down by a substantially cylindrical push member 125 with both ends open. Details of the sealing member 124 will be described later. The push member 125 abuts against the inner surface of the lid 120 (the surface facing the first liquid chamber 111) at one end and abuts against the sealing member 124 at the other end. The push member 125 is provided with a through hole 125a through which the first liquid flow path 112 opens.

[0026] The second liquid chamber 113 is substantially cylindrical and comprises a side wall 113a, a bottom portion 113b surrounding the communication hole 115, and an opening 113c that opens on the opposite side of the bottom portion 113b. The opening 113c is liquid-tightly sealed by a flexible member 130, which is a flexible film. The flexible member 130 is fixed around the edge of the opening 113c by heat welding or the like.

[0027] A valve stem 131, fixed to a flexible member 130, is housed within the second liquid chamber 113. The valve stem 131 moves through the communication hole 115 in conjunction with the deflection of the flexible member 130 due to fluctuations in the liquid pressure in the second liquid chamber 113. The valve stem 131 passes through the communication hole 115 at one end and has a pressure receiving plate 131a at the other end. The pressure receiving plate 131a is fixed to the inner surface of the flexible member 130 (the surface facing the second liquid chamber 113) by heat welding or the like. In order to prevent the pressure receiving plate 131a from tilting as much as possible in response to the deflection of the flexible member 130, and to allow it to move while maintaining a right angle to the center line of the communication hole 115, for example, the pressure receiving plate 131a is biased by a second elastic member 132 in a direction away from the first liquid chamber 111. The second elastic member 132 is, for example, a spring such as a compression coil spring. For example, one end of the second elastic member 132 is fixed to an elastic member fixing part 131b provided on the surface of the pressure receiving plate 131a of the valve stem 131 facing the bottom 113b of the second liquid chamber 113, and the other end is fixed to an elastic member fixing part 113d provided on the bottom 113b of the second liquid chamber 113.

[0028] The materials of the valve body 110, lid 120, valve element 121, valve seat 123, push member 125, and valve stem 131 are, independently, metal or resin. The materials of the first elastic member 122 and the second elastic member 132 are any elastic material, for example, metal.

[0029] (Operation of pressure damper 100) When no liquid is being sprayed from the liquid injection head, the valve body 121 is biased toward the second liquid chamber 113 by the first elastic member 122 within the first liquid chamber 111. As a result, as shown in Figures 1(a) and (b), the valve body 121 moves to the closed position and contacts the sealing member 124 on the valve seat 123, closing the communication hole 115. This prevents liquid from flowing from the first liquid chamber 111 to the second liquid chamber 113. This operation of the pressure damper 100 is called valve closing operation.

[0030] On the other hand, when liquid is being sprayed from the liquid injection head, the amount of liquid in the second liquid chamber 113 decreases, and the second liquid chamber 113 becomes negatively pressurized. Consequently, the flexible member 130 bends, and the central part of the flexible member 130 and the pressure receiving plate 131a are displaced toward the first liquid chamber against the second elastic member 132. The bent central part of the flexible member 130 and the pressure receiving plate 131a press the valve stem 131 against the valve body 121, and the valve stem 131 pushes the valve body 121 against the first elastic member 122. As a result, as shown in Figures 1(b) and (d), the valve body 121 separates from the sealing member 124 and the valve seat 123, opening the communication hole 115. This allows liquid to flow from the first liquid chamber 111 to the second liquid chamber 113. This operation of the pressure damper 100 is called the valve opening operation.

[0031] (Configuration of sealing member 124) As shown in Figure 2(a), the sealing member 124 is an annular member configured to seal the space between the valve body 121 and the communication hole 115 when the valve body 121 closes the communication hole 115. The material of the sealing member 124 is any elastic material, such as ethylene propylene diene rubber (EPDM), butyl rubber, or silicone rubber. The sealing member 124 also has a Shore A hardness of, for example, 30 to 60 degrees, preferably 35 to 55 degrees, and more preferably 40 to 50 degrees.

[0032] As shown in Figure 2(b) and Figures 3(a) to (d), the sealing member 124 comprises an outer circumference 124a, an inner circumference 124b, and a connecting portion 124c that flexibly connects the outer circumference 124a and the inner circumference 124b. The connecting portion 124c is formed to be thinner than the outer circumference 124a and the inner circumference 124b, and as shown in Figure 3(d), when the valve body 121 presses the sealing member 124, the sealing member 124 is deformed such that the inner circumference 124b tilts relative to the outer circumference 124a.

[0033] The outer peripheral portion 124a abuts against the side wall 111a of the first liquid chamber 111 when the sealing member 124 is inserted into the first liquid chamber 111, but does not abut against the bottom portion 111b. The outer peripheral portion 124a further comprises a protruding portion 124aa that protrudes toward the side wall 111a and a non-protruding portion 124ab that does not protrude.

[0034] As shown in Figure 2(b) and Figure 3(a), the inner diameter of the portion of the side wall 111a of the first liquid chamber 111 that abuts the outer periphery 124a is W １ Therefore, the outer diameter W of the protruding portion 124aa is as follows: ４ is W １ Larger, outer diameter W of the non-protruding portion 124ab ５ is W １ The following is the case. Therefore, when the sealing member 124 is inserted into the first liquid chamber 111, as shown in Figure 3(a), the protruding portion 124aa catches on the side wall 111a of the first liquid chamber 111, so as shown in Figure 3(c), the entire side surface of the outer peripheral portion 124a conforms to the side wall 111a, and deforms so that, for example, in the cross-section of the sealing member 124 along the center line, the angle between the side surface of the protruding portion 124aa and the side surface of the non-protruding portion 124ab approaches 180 degrees, for example, so that it becomes flush.

[0035] At this time, the protrusion 124aa, due to its restoring force, presses against the side wall 111a with a predetermined force, and consequently with a first pressure greater than or equal to a predetermined pressure. As a result, the liquid tightness between the outer periphery 124a and the side wall 111a, particularly the liquid tightness between the protrusion 124aa and the side wall 111a, is improved compared to the case where the protrusion 124aa is not present.

[0036] Furthermore, when the outer periphery 124a is pressed down by the pressing member 125, the pressing force (black arrow in the figure) compresses the outer periphery 124a, causing a slight deformation (white arrow in the figure) along the direction perpendicular to the pressing force to the outer periphery 124a, particularly the protruding portion 124aa. This deformation increases the force with which the outer periphery 124a, particularly the protruding portion 124aa, presses against the side wall 111a. As a result, the liquid-tightness between the outer periphery 124a and the side wall 111a, particularly between the protruding portion 124aa and the side wall 111a, is further improved.

[0037] As shown in Figure 3(d), the inner circumference 124b is sandwiched between the valve body 121 and the valve seat 123 when the valve body 121 closes the communication hole 115. The inner circumference 124b is formed such that, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111, most of it is contained within the region outside the communication hole 115 and inside the outer circumference of the valve body 121. For example, if the inner diameter of the communication hole 115 is W ２When the outer diameter of the valve body 121 is W ３ the inner peripheral portion 124b has an inner diameter approximately the same as W, particularly larger than W, and an outer diameter approximately the same as W, particularly smaller than W, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111. ２ the inner peripheral portion 124b has an inner diameter approximately the same as W, particularly larger than W, and an outer diameter approximately the same as W, particularly smaller than W, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111. ２ the inner peripheral portion 124b has an inner diameter approximately the same as W, particularly larger than W, and an outer diameter approximately the same as W, particularly smaller than W, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111. ３ the inner peripheral portion 124b has an inner diameter approximately the same as W, particularly larger than W, and an outer diameter approximately the same as W, particularly smaller than W, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111. ３ the inner peripheral portion 124b has an inner diameter approximately the same as W, particularly larger than W, and an outer diameter approximately the same as W, particularly smaller than W, when viewed from the direction in which the sealing member 124 is inserted into the first liquid chamber 111.

[0038] The inner peripheral portion 124b includes a contact surface 124ba that comes into surface contact with the valve body 121 when the valve body 121 closes the communication hole 115, a contact surface 124bb that comes into surface contact with the upper surface 123a (the surface facing the valve body 121) of the valve seat 123 when the valve body 121 closes the communication hole 115, and an engagement portion 124bc that engages with the inner side surface 123b of the valve seat 123 when the valve body 121 closes the communication hole 115.

[0039] As shown in (d) of FIG. 3, when the inner peripheral portion 124b is sandwiched between the valve body 121 and the valve seat 123 when the valve body 121 closes the communication hole 115, the force applied from the valve body 121 to the inner peripheral portion 124b via the contact surface 124ba and the force applied from the upper surface 123a of the valve seat 123 to the inner peripheral portion 124b via the contact surface 124bb (black arrows in the figure) compress the inner peripheral portion 124b and cause some deformation (white arrows in the figure) along the direction perpendicular to these forces. Here, since the sealing member 124 pushes back the valve body 121 by the restoring force, the force applied from the upper surface 123a of the valve seat 123 to the inner peripheral portion 124b via the contact surface 124bb is smaller than the force applied from the valve body 121 to the inner peripheral portion 124b via the contact surface 124ba by the amount of this pushing-back force. However, the restoring force of the sealing member 124 and, if necessary, the contact area between the contact surface 124bb of the inner peripheral portion 124b and the upper surface 123a of the valve seat 123 are adjusted so that the second pressure received by the inner peripheral portion 124b from the valve seat 123 when the valve body 121 is in the closed position is not less than a predetermined pressure, so the second pressure is not less than the predetermined pressure. Also, the restoring force of the sealing member 124 and, if necessary, the contact area between the contact surface 124ba of the inner peripheral portion 124b and the valve body 121 are adjusted so that the third pressure received by the inner peripheral portion 124b from the valve body 121 when the valve body 121 is in the closed position is not less than a predetermined pressure, so the third pressure is not less than the predetermined pressure.

[0040] As can be seen by comparing the cross-section of the engaging portion 124bc of the sealing member 124 with the dotted line of the valve seat 123 when the inner circumference 124b is tilted with respect to the outer circumference 124a to the same extent as in Figure 3(d) shown in Figure 3(b), and the contact surface 124bb is superimposed on the dotted line of the inner surface of the first liquid chamber 111, when the valve body 121 closes the communication hole 115, the engaging portion 124bc presses against the side surface 123b of the valve seat 123 and makes close contact with it, as shown in Figure 3(d).

[0041] Conventionally, if the liquid spray head consumes even a small amount of liquid, for example, if the liquid spray device is a printing device, when the liquid spray device performs normal printing, printing with low liquid consumption, or flushing to clean the nozzle of the liquid spray head, the negative pressure in the second liquid chamber 113 exceeds a threshold, and the valve body 121 is pushed back towards the first liquid chamber 111, causing the valve body 121 to immediately separate from the sealing member 124 and become non-contact with the sealing member 124. However, in this embodiment, as shown in Figure 4, due to the restoring force of the sealing member 124 that has been bent by the valve body 121, when the negative pressure in the second liquid chamber 113 is near the aforementioned threshold, at least a portion of the contact surface 124ba of the inner circumference 124b of the sealing member 124 remains in contact with the valve body 121 until the sealing member 124 returns to its shape before being bent by the valve body 121. When the liquid spray head performs a first operation in which it consumes liquid at a rate greater than or equal to a certain liquid consumption rate, for example, when performing a normal printing operation, the negative pressure in the second liquid chamber 113 is greater than or equal to the first negative pressure, and the valve body 121 is pushed toward the first liquid chamber 111 with a force greater than or equal to the first opening force. When the liquid spray head performs a second operation in which it consumes liquid at a rate less than the aforementioned liquid consumption rate, for example, when performing a low-liquid-consumption printing operation or a flushing operation, the negative pressure in the second liquid chamber 113 is less than the first negative pressure but greater than or equal to the second negative pressure, and the valve body 121 is pushed back toward the first liquid chamber 111 with a force less than the first opening force but greater than or equal to the second opening force. In this case, the first negative pressure is the negative pressure in the second liquid chamber 113 required for opening the valve, taking into account the force with which the sealing member 124, which is bent by the valve body 121, pushes back against the valve body 121 due to its restoring force, and the second negative pressure is the negative pressure in the second liquid chamber 113 required for opening the valve, when this pushing force is not taken into consideration. Similarly, the first valve opening force is the force with which the valve body 121 is pushed towards the first liquid chamber 111 by the first negative pressure, required for opening the valve, taking into account the aforementioned pushing force of the sealing member 124, and the second valve opening force is the force with which the valve body 121 is pushed towards the first liquid chamber 111 by the second negative pressure, required for opening the valve, when the aforementioned pushing force of the sealing member 124 is not taken into consideration. When the liquid injection device is performing the second operation, the force with which the inner circumference 124b is pushed by the valve body 121 is smaller than the second valve opening force, which is the force with which the inner circumference 124b is pushed by the valve body 121 when the valve body 121 is in the closed position.

[0042] (Advantages of the Present Invention) In a conventional pressure damper, even when the valve body closes the communication hole and liquid does not flow from the first liquid chamber where liquid is first supplied from the liquid storage means to the second liquid chamber that supplies liquid to the liquid injection head through the communication hole, liquid may flow from the first liquid chamber to the second liquid chamber through the back surface and / or side surface (i.e., the surface that does not contact the valve body) of the sealing member that seals between the valve body and the communication hole.

[0043] For example, as shown in FIG. 7, a conventional pressure damper 500 has the same configuration as the pressure damper 100 according to the above-described embodiment, except that a sealing member 524 having a shape adapted to the side surface, bottom, and valve seat of the first liquid chamber is used instead of the sealing member 124. However, due to processing accuracy issues, when the outer diameter of the sealing member 524 is smaller than expected from the inner diameter of the side wall 111a of the first liquid chamber 111, a gap may be formed through which liquid can flow between the sealing member 524 and the side wall 111a of the first liquid chamber 111. Also, when the outer diameter of the sealing member 524 is larger than expected from the inner diameter of the side wall 111a of the first liquid chamber 111, the entire sealing member 524 may be distorted, and part or all of the sealing member 524 may lift off from the valve seat 123, forming a gap through which liquid can flow between the sealing member 524 and the valve seat 123.

[0044] Also, if liquid continuously flows from the first liquid chamber to the second liquid chamber through the back surface and / or side surface of the sealing member that seals between the valve body and the communication hole, deposition components contained in the liquid, such as pigment particles contained in paint, may accumulate on the back surface and / or side surface of the sealing member, widening the gap between the back surface and / or side surface of the sealing member, increasing the amount of liquid leaking from the gap, and significantly impairing the sealing valve function in the pressure damper.

[0045] On the other hand, according to the above-described embodiment, since the protruding portion 124aa is provided on the outer peripheral portion 124a of the sealing member 124, a first pressure above a predetermined pressure at which good liquid tightness is expected to be obtained between the protruding portion 124aa and the side wall 111a of the first liquid chamber 111 is applied, and as a result, the liquid tightness between the sealing member 124 and the side wall 111a is improved.

[0046] Furthermore, since a flexible connecting portion 124c is provided between the outer circumference 124a and the inner circumference 124b of the sealing member 124, when the valve body 121 presses against the sealing member 124, the inner circumference 124b tilts relative to the outer circumference 124a. As a result, the inner circumference 124b and the valve seat 123 and valve body 121 come into close contact at second and third pressures exceeding a predetermined pressure at which good liquid tightness is expected to be obtained, thereby improving the liquid tightness between the inner circumference 124b and the valve body 121 and valve seat 123. In particular, even if the strain of the sealing member 124 could create a gap between the sealing member 124 and the valve seat 123 large enough for liquid to flow, for example, between the contact surface 124bb and the upper surface 123a of the valve seat 123 and / or between the engaging portion 124bc and the side surface 123b of the valve seat 123, the strain is absorbed by the bending at the connecting portion 124c, so that the inner circumference 124b and the valve seat 123 are in close contact when the valve is closed.

[0047] Furthermore, the conventional pressure damper 500 is configured to open the valve even when the amount of liquid sprayed from the liquid spray head is small, for example, during flushing. Therefore, when the amount of liquid sprayed from the liquid spray head is small, the valve is repeatedly opened and closed in a short period of time, causing the flow rate of the liquid flowing through the communication hole 115 to change drastically in a short period of time, resulting in unstable valve operation. On the other hand, the pressure damper 100 according to this embodiment is configured so that the valve body 121 maintains contact with the inner circumference 124b when the amount of liquid sprayed from the liquid spray head is small. Therefore, when the amount of liquid sprayed from the liquid spray head is small, the valve is loosely sealed, and the flow rate of the liquid is restricted. At this time, because the flow rate of the liquid flowing through the communication hole 115 is restricted, the valve operation remains stable even if the valve is repeatedly opened and closed in a short period of time.

[0048] (Modification) In the above embodiment, the pressure damper 100, excluding the sealing member 124, can be configured arbitrarily according to well-known technology, as long as it is compatible with the sealing member 124.

[0049] For example, the pressure damper 100 may include a first liquid chamber from which liquid is supplied from a liquid storage means, a second liquid chamber for which liquid is supplied to a liquid injection head, a communication hole for liquid communication between the first and second liquid chambers, a flexible member that forms part of the wall surface of the second liquid chamber and is displaced based on pressure fluctuations in the second liquid chamber, a valve body configured to move between a closed position that closes the communication hole and an open position that opens the communication hole, and an elastic member that biases the valve body to always be held in the closed position, and displaces the valve body from the posture that holds it in the closed position when it receives a pressing force from the flexible member due to the inward displacement of the flexible member in the second liquid chamber. In this case, the valve body moves from the closed position to the open position based on the inward displacement of the flexible member in the second liquid chamber.

[0050] The sealing member 124 comprises an outer circumferential portion that presses against the side wall of the first liquid chamber of the pressure damper with a pressure equal to or greater than a predetermined pressure when the sealing member 124 is mounted on the pressure damper, and an inner circumferential portion that is pressed against the valve body and pressed against the valve seat during the valve closing operation. The sealing member 124 should be configured to flex when the inner circumferential portion is pressed against the valve body during the valve closing operation, with a restoring force that prevents the pressure received by the inner circumferential portion from the valve seat from falling below a predetermined pressure when the valve body is in the closed position. With such a configuration, when the valve is closed in the pressure damper, the sealing member 124 will come into contact with the side wall of the first liquid chamber, the valve body, and the valve seat with a pressure equal to or greater than a predetermined pressure, which is expected to provide good liquid tightness.

[0051] The shape of the outer periphery 124a is arbitrary, as long as the outer periphery 124a is pressed against the side wall 111a of the first liquid chamber 111 with a pressure equal to or greater than a predetermined pressure.

[0052] For example, in the above embodiment, the protrusions 124aa of the outer periphery 124a are formed on the side of the outer periphery 124a that contacts the push-in member 125, but the position, number, and shape of the protrusions 124aa on the outer periphery 124a are arbitrary. For example, as shown in Figure 5, the protrusions 124aa may be formed in the center of the side surface of the outer periphery 124a. Regardless of the position, number, and shape of the protrusions 124aa on the outer periphery 124a, if the maximum outer diameter of the entire protrusions 124aa is larger than the inner diameter of the side wall 111a of the first liquid chamber 111, the liquid tightness between the sealing member 124 and the side wall 111a of the first liquid chamber 111 is improved.

[0053] Furthermore, if the outer peripheral portion 124a is pressed against the side wall 111a of the first liquid chamber 111 with a pressure greater than a predetermined pressure, the protruding portion 124aa from the outer peripheral portion 124a may be omitted, and the outer diameter of the outer peripheral portion 124a may be made larger than the inner diameter of the side wall 111a of the first liquid chamber 111. In this case, when the sealing member 124 is attached to the pressure damper 100, the sealing member 124 may be distorted, but such distortion can be absorbed by the deflection of the sealing member 124, in particular by the bending at the connection portion 124c described above or by the inclination of the inner peripheral portion 124b itself, which will be described later.

[0054] If the inner circumference 124b is pushed by the valve body 121 during the valve closing operation and pressed against the valve seat 123, and the sealing member 124 is configured to bend when the inner circumference 124b is pushed by the valve body 121 during the valve closing operation, with a restoring force that prevents the pressure received by the inner circumference 124b from the valve seat 123 when the valve body 121 is in the closed position from falling below a predetermined pressure, then the configuration and shape of the sealing member 124, in particular the configuration and shape of the inner circumference 124b and the connecting portion 124c, are arbitrary.

[0055] For example, in the above embodiment, the sealing member 124 bends so that the inner circumference 124b tilts relative to the outer circumference 124a due to the connecting portion 124c. However, the sealing member 124 may be configured so that the inner circumference 124b itself tilts relative to the outer circumference 124a, either in addition to or without the connecting portion 124c. For example, as shown in Figure 6, the connecting portion 124c may be omitted, and the outer circumference 124a and the inner circumference 124b may be directly connected, so that the inner circumference 124b itself bends.

[0056] In the open state, there should be a gap between the inner circumference 124b and the valve seat 123 so that the sealing member 124 can bend when pressed by the valve body 121 during the valve closing operation.

[0057] The sealing member 124 is configured to return to its original state while maintaining contact between the valve body 121 and the inner circumference 124b when the liquid injection head is performing the second operation. The configuration and shape of the sealing member 124, particularly the configuration and shape of the portion of the inner circumference 124b that maintains contact with the valve body 121, are arbitrary. For example, in Figure 4, the portion of the inner circumference 124b that maintains contact with the valve body 121 when the liquid injection head is performing the second operation is shown as a rounded portion provided on the inner circumference side of the contact surface 124ba of the inner circumference 124b. However, the position of this portion may be at other positions on the contact surface 124ba, for example, in the center or on the outer circumference, and there may be two or more such portions. The cross-sectional shape of this portion may include straight edges instead of a rounded cross-section.

[0058] The restoring force of the sealing member 124, which has bent during the valve closing operation, can be adjusted by adjusting the shape, strength, hardness, etc., of the sealing member 124, particularly the inner circumference 124b and / or the connecting portion 124c. For example, if the thickness of the sealing member 124, particularly the thickness of the inner circumference 124b and / or the connecting portion 124c, is made thinner in the direction of movement of the valve body 121, the restoring force will be weakened, and if it is made thicker, it will be increased. Also, for example, if the sealing member 124, particularly the inner circumference 124b and / or the connecting portion 124c, is provided with depressions or through holes in the direction of movement of the valve body 121 and / or continuous or intermittent hollow portions along the circumferential direction, the restoring force will be weakened. Furthermore, for example, if a material with low hardness is used for the sealing member 124, particularly the inner circumference 124b and / or the connecting portion 124c, the restoring force will be weakened, and if a material with high hardness is used, it will be increased. For example, the hardness of a material can be adjusted by increasing or decreasing the amount of hardness modifier added to its raw materials.

[0059] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure.

[0060] 100, 500 Pressure damper 110 Valve body 111 First liquid chamber 111a, 113a Side wall 111b, 113b Bottom 111c, 113c Opening 112 First liquid flow path 113 Second liquid chamber 113d, 120a, 121a, 131b Elastic member fixing part 114 Second liquid flow path 115 Communication hole 120 Cover 120b Holding part 121 Valve body 122 First elastic member 123 Valve seat 123a Top surface 123b Side surface 124, 524 Sealing member 124a Outer circumference 124aa Protruding part 124ab Non-protruding part 124b Inner circumference 124ba, 124bb Contact surface 124bc Engaging part 124c Connection part 125 Push-in member 125a Through hole 130 Flexible member 131 Valve stem 131a Pressure receiving plate 132 Second elastic member

Claims

1. An annular sealing member for sealing the space between a valve body and a valve seat and between the valve body and the side wall of a liquid chamber housing the valve body in a liquid injection device, wherein the sealing member comprises an outer circumferential portion that presses the side wall with a pressure greater than or equal to a predetermined pressure when the sealing member is mounted on the pressure damper, and an inner circumferential portion that is pressed against the valve seat by the valve body during a valve closing operation, and the sealing member is configured to flex when the inner circumferential portion is pressed against the valve body during a valve closing operation, with a restoring force that prevents the pressure received by the inner circumferential portion from the valve seat from falling below the predetermined pressure when the valve body is in the closed position.

2. When the valve body is in the closed position, the force acting on the inner circumference from the upper surface of the valve seat is less than the force acting on the inner circumference from the valve body, as described in claim 1.

3. The sealing member according to claim 1, wherein the valve is opened only when the liquid spray head consumes the liquid at a speed equal to or greater than a certain liquid consumption rate, and when the first operation in which the liquid spray head consumes the liquid at a speed equal to or greater than the liquid consumption rate is being performed, the valve body separates from the inner circumference and becomes non-contact with the inner circumference, and the sealing member is configured to return to its original position while maintaining contact between the valve body and the inner circumference when the liquid spray head is performing a second operation in which the liquid spray head consumes the liquid at a speed less than the liquid consumption rate.

4. The sealing member according to claim 3, wherein the force with which the inner circumference is pressed against the valve body when the liquid injection head is performing the second operation is less than the force with which the inner circumference is pressed against the valve body when the valve body is in the closed position.

5. A liquid injection device comprising a pressure damper including a sealing member as described in any one of claims 1 to 4.

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