JPS5819864B2 - fluid supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fluid supply device that can supply a small amount of fluid and ensure a constant flow rate. This is related to.

Generally, many diaphragm type constant flow pumps are in practical use, but due to their structure, the stroke of the diaphragm is inevitably large, resulting in a large flow rate, and it is necessary to supply a small amount of ink like an inkjet printer. It is inappropriate for those who have

If this product were to be used as a minute metering pump, the stroke of the diaphragm would have to be set extremely small, which would not only be difficult to manufacture, but the small stroke would also prevent the diaphragm from deforming even slightly. This results in loss of quantitative properties.

Furthermore, there is a piston-type small constant flow pump that uses a piston, but this type has an O-ring attached to the piston to seal between the cylinder and the piston, and the piston slides inside the cylinder. However, there are drawbacks such as fluid leakage due to abrasion of O-rings and the like due to the above-mentioned sliding.

The present invention provides a fluid supply device that solves the problems of the constant flow pump described above.

In particular, in order to be able to supply a small amount of fluid and to prevent the occurrence of fluid leakage, there is a piston that moves forward and backward with respect to the pressure chamber (first pressure chamber), and a piston of the pressure chamber that moves forward and backward. The pump has a bellows that partitions the side where the piston moves and performs a rolling action as the piston moves.

In addition, in order to prevent flow rate fluctuations due to deformation of the bellows and unstable operation of the valve of the pressure chamber (first pressure chamber),
A second pressure chamber having a large capacity and always having a lower pressure than the pressure chamber is provided adjacent to the bellows of the pressure chamber (first pressure chamber), and the pressurized fluid discharged from the second pressure chamber is The pressure chamber (first pressure chamber) is guided to the pressure chamber (first pressure chamber).
This is a fluid supply device that can supply a constant flow rate by discharging fluid from the fluid into the system.

Furthermore, since the capacities of the second pressure chamber and the first pressure chamber are different, the flow rate between the second pressure chamber and the first pressure chamber must be adjusted between the two pressure chambers (for buffering purposes). In addition, the fluid supply device is equipped with a pressure accumulation chamber for smoothing pulsating flow.

The present invention will be described below based on an embodiment implemented in an ink supply device for an inkjet printer.

In the figure, 1 is a nozzle that ejects ink sent from an ink supply device via a solenoid valve 11, 2 is an ultrasonic vibrator that is attached to the nozzle 1 and converts the ejected ink into particles in synchronization with the vibration cycle. Reference numeral 3 denotes a charging electrode for applying a charge to the ink particles 4 according to input information (video signal), and 5 a constant high voltage that deflects the charged ink particles 4 according to the amount of charge. This is the supplied deflection electrode.

The deflected ink particles 4 reach the recording paper 6 and form a desired dot pattern.

On the other hand, ink particles 4' that are not used for recording pass through the deflection electrode 5 and are collected by the ink collection gutter 7 without being charged.

The nozzle 1, vibrator 2, charging electrode 3, deflection electrode 5 and gutter 7 are mounted on a carriage 8 indicated by a dotted line,
It is driven back and forth on sliding shafts 9, 9 provided parallel to the recording paper.

This serves to deflect the dot pattern in the lateral direction.

The ink collected in the gutter 7 follows a circulation path in which it is led to the ink supply device via the piping 10 and is ejected from the ejection nozzle 1 again.

Next, the above ink supply device will be explained.

The recovered ink from the piping 10 flows out from the piping 12 through a constant flow pump, and is injected from the nozzle 1 via the electromagnetic valve 11 described above.

The ink that flows out into the pipe 12 is the ink that has been added to the used ink and the viscosity of the ink is kept constant.

Therefore, the ink ejected from the nozzle 1 has a constant flow rate and a constant viscosity, and the ink particles that are formed into particles are regular, so that accurate printing can be expected.

A constant flow pump consists of three connected cylinders 13.14
．． Bellows 19.20 for each of the 15 cavities.

Each pressure chamber 16, 17, 18 is separated by 21, and the pressure in each pressure chamber is increased or decreased by rolling the bellows 19, 20, 21 along each pressure chamber.

The diameter of the bellows 192021 becomes smaller in order, and each peripheral edge is clamped and fixed between the cylinder 13 and a bearing holding part 29, which will be described later, between the cylinders 14 and 13, and between the cylinders 15 and 14, respectively.

Also, the center part of the bellows 19°20.21 is connected to each pressure chamber 16.
The bellows 19 is connected to the piston 22 by the piston 23, and the bellows 20 is connected to the piston 24 through caps on the end surfaces of the pistons 22, 23, and 24, which are moved forward and backward in accordance with 17.18 and are connected coaxially, respectively. A bellows 21 is fixed to the piston 23 with a screw 25.

The pistons 222324 are connected to each other in order of decreasing diameter, and by driving the pistons 22 left and right (in the force direction of arrow AB), each bellows 19, 20, and 21 are rolled in a concave shape as shown in the figure, and pressure is applied. Room 161718
Increase or decrease the pressure inside.

The piston 22 is driven by a structure in which an eccentric cam 27 connected to a drive source (not shown) is constantly brought into contact with a bearing 26 attached to the piston by the biasing force of a spring 28. According to the rotation in the direction, the piston 22 is driven in the direction of the force indicated by the arrow AB.

The piston 22 is movably held by a bearing 30 attached to a bearing holding part 29, and the stroke amount is adjusted by a flow rate adjustment screw 31 screwed into a hole in the bearing holding part 29.
It is variable at will.

In other words, the flow rate adjusting screw 31 changes the stroke amount of the piston 22, thereby changing the flow rate.

On the other hand, each cylinder 13, 14, 15 is provided with an inflow/outflow valve mechanism.

The inflow valve mechanism 32 of the cylinder 13 is connected to a pipe 10 that guides the ink collected in the gutter 7, and the outflow valve mechanism 33 is connected to a sub-tank 35 via a pipe 34.

The sub-tank 35 is configured to always store a fixed amount of ink, such as recovered ink and new ink drawn from the ink cartridge 36 via a switching solenoid valve 38. help supply.

The reference numeral 36 is an ink solvent cartridge, and the solenoid valve 3
8, the ink solvent is led to the sub-tank 35.

Further, the sub-tank 35 is provided with a filter 39, and the ink in the sub-tank 35 is guided to the piping 40 via the filter 39.

This pipe 40 is connected to an inflow valve mechanism 41 of the cylinder 14.

The pressure chamber 17 of the cylinder 14 communicates with a pressure accumulation chamber 43 via an outflow valve mechanism 42.

This pressure accumulating chamber 43 has a circumferential edge inside the cylinder 44.
4 is provided with a bellows 45 fixed to it, and the bellows 45 is biased by a spring 47 via a cap 46.

The cylinder 44 is provided with an outflow valve mechanism 48,
The pressure storage chamber 43 and the sub-tank 3 are connected to each other via this valve mechanism 48.
5 is connected to piping 49.

Further, the pressure chamber 18 of the cylinder 15 and the pressure accumulation chamber 43 are also communicated via an inflow valve mechanism 50 of the cylinder 15 through a passage 52 provided in the cylinder 44 and a cylinder 51 to be described later.

Further, the pressure chamber 18 communicates with a pressure accumulation chamber 54 via an outflow valve mechanism 53 provided in the cylinder 15.

This pressure accumulation chamber 54 has a circumferential edge inside the cylinder 51.
1 is provided with a bellows 55 fixed to it, and this bellows 55 is biased by a spring 57 via a cap 56.

Further, a pin 58 protruding from the cylinder 51 is fixed to the cap 56, and an operating piece 60 of a microswitch 59 is provided opposite the pin 58.

That is, the solenoid valve drive circuit 61 is activated by the operation of the microswitch 59, and the solenoid valve 38 is switched.

Therefore, since new ink from the ink cartridge 36 is led to the sub-tank 35, the ink solvent in the ink solvent cartridge 31 is led to the sub-tank 35 by switching the solenoid valve 38, so that the viscosity of the ink is always kept constant. I have to.

Further, the pressure accumulation chamber 54 is connected to the pipe 12 via a filter 62.

Each of the above-mentioned inflow and outflow valve mechanisms includes a ball valve, a valve seat whose flow path is closed by the ball valve, and a spring that constantly brings the ball valve into contact with the valve seat.

In addition, a pressure accumulator 4 is provided corresponding to the pressure chambers 17 and 18.
3 and 54 are for smoothing the pulsation of the fluid flowing in from the corresponding pressure chamber (pulsation accompanying the forward and backward movement of the piston).

Further, since the pressure chambers 17 and 18 have different capacities, the pressure accumulation chamber 43 acts as a buffer for adjusting the fluid between the two pressure chambers.

For this reason, the valve mechanism 48 provided in the pressure accumulation chamber 43
The pressure of the spring that biases the ball valve is adjusted so that it opens when the pressure No. 3 reaches a certain level.

In other words, as will be described later, when the pressure chambers 17 and 18 are in the process of discharging fluid, the valve mechanism 50 is opened due to the pressure increase in the pressure accumulation chamber 43, or the pressure chamber 17 is guided to a higher pressure than the pressure chamber 18. In order to prevent this, the valve mechanism 48 is energized with a force smaller than that of the valve mechanism 50 and the pressure accumulator 4 is energized.
The valve is provided with a biasing force to open at a predetermined pressure before the internal pressure of the pressure chamber 17 reaches the internal pressure of the pressure chamber 17 or higher.

In the above configuration, the piston 22 reciprocates left and right as the eccentric cam 27 rotates.

Therefore, each piston 22, 23, 24 moves forward and backward with respect to each pressure chamber 16, 17, 18, and a certain amount of ink is ejected from the nozzle 1.

Accordingly, the charged ink particles 4 contribute to printing, but the ink particles 4' are recovered by the ink recovery gutter 7.

This collected ink is collected by moving the piston 22 in the direction B, and since the diameter of the bellows 20 is smaller than that of the bellows 19, the pressure in the pressure chamber 16 decreases, and the ball valve of the valve mechanism 32 resists the spring. is pushed up and sucked into the pressure chamber 16.

Further, when the piston 22 moves in the direction A, the pressure inside the pressure chamber 16 increases, and at this time the ball valve of the valve mechanism 33 is pushed up, and the recovered ink flows through the pipe 34 to the sub tank 35.
is discharged to.

Here, if the amount of collected ink is small, new ink is introduced from the ink cartridge 36 into the sub-tank 35, so that a constant amount of ink is always injected into the sub-tank 35.

On the other hand, as the piston 22 moves in the direction B, the pressure in the pressure chamber 17 decreases as the piston 22 moves in the direction B and the bellows 20 is larger than the bellows 21.

As a result, the valve mechanism 41 opens, and the ink from which dirt and air bubbles have been removed by the filter 39 is sucked into the pressure chamber 17 from the sub-tank 35 .

At the same time, the pressure in the pressure chamber 18 is set to be lower than the pressure in the pressure accumulation chamber 43.
The pressurized ink in 3 flows through the valve mechanism 50.

In this case, the ink flows into the pressure chamber 18 effectively, which helps to supply a constant amount of ink.

In other words, even if the opening operation of the valve mechanism 50 is unstable, the instability of the valve is compensated for by introducing pressurized ink from the pressure accumulation chamber 43 into the pressure chamber 18, and a constant flow of ink is supplied. It is secured.

If the piston 22 moves in the A direction, the pressure chamber 17
The pressure increases, the outflow valve mechanism 42 opens, and the pressure chamber 1
The ink sucked into the pressure storage chamber 43 is discharged into the pressure storage chamber 43.

Similarly, the pressure in the pressure chamber 18 also increases, and the valve mechanism 53 opens and the ink in the pressure chamber 18 is discharged into the pressure accumulation chamber 54.

Therefore, the ink in this pressure accumulation chamber 54 passes through the filter 62 to remove dust and the like from the ink, and the piping 12 and solenoid valve 1
1 to the nozzle 1, and a constant amount of ink is always ejected from the nozzle 1.

In this case, the flow rate discharged from the pressure chamber 18 to the pressure accumulation chamber 54 is smaller than the flow rate discharged from the pressure chamber 17 to the pressure accumulation chamber 43, so that the pressure in the pressure chamber 43 or the pressure chamber 17 is higher than the pressure in the pressure chamber 18. It may happen.

To prevent this, a spring energizes the ball valve so that when the pressure inside the pressure storage chamber 43 exceeds a certain pressure, the valve mechanism 48 opens and ink is discharged into the sub-tank 35 via the valve mechanism 4B. is set.

Therefore, when the piston moves in the A direction, the pressure in the pressure accumulation chamber 43 does not become higher than the pressure in the pressure chamber 18, and the valve mechanism 5
0 never opens.

In this way, the pressure in the pressure storage chamber 43 is maintained at a pressure that does not deform the bellows 21.

Note that when the valve mechanism 48 opens, the ink in the pressure accumulation chamber 43 is guided to the sub-tank 35 via the piping 49.

As mentioned above, any movement of the piston will result in pressure chamber 18
On the other hand, if the pressure in the pressure chamber 17 is negative and the bellows 21 is not deformed and the rotation of the cam 27 is constant, the flow rate of ink flowing into the pipe 12 is always constant, and the nozzle 1
A more constant amount of ink will be ejected.

As described above, according to the present invention, the first pressure chamber 18 has holes for fluid inflow and outflow, the first piston 24 moves forward and backward with respect to the first pressure chamber, and the first pressure chamber 18 has holes for fluid inflow and outflow. a first bellows 21 that seals the gap between the piston and the wall of the first pressure chamber housing the piston on the side where the piston 24 of the first pressure chamber 18 is located and rolls as the piston moves; , a first inflow valve 50 on which a constant biasing force is applied by a spring, which opens and closes the fluid inflow/outflow hole in response to the forward/backward (intake/exhaust) movement of the first piston; The first bellows 21 has an outflow valve 53 and holes for fluid inflow and outflow.
A second pressure chamber 17 is provided adjacent to the first pressure chamber on the same axis as the first pressure chamber and has a larger diameter than the first pressure chamber 18, and performs movement toward and away from the second pressure chamber. a second piston 23 having a larger diameter than the first piston, which is connected to the first piston 24 at one end and is disposed on one axis; On the side where the piston 23 is located, the second piston and the second piston that accommodates this piston are located.
a second bellows 20 that seals a gap with the wall of the pressure chamber and rolls as the piston moves; and a hole for fluid inflow and outflow in response to the movement of the second piston. A second inflow valve 41 and a second outflow valve 42 to which a constant urging force is applied by a spring are applied to open and close; one reciprocating drive source connected to the other end of the second piston; and an inflow hole. is connected to the second outflow valve of the second pressure chamber, and the outflow hole is connected to the first inflow valve of the first pressure chamber, and the pressure accumulation chamber 43 is connected to the outside. a valve 48 that normally closes another communicating hole under the force of a spring and closes when the pressure inside the pressure accumulation chamber rises above a predetermined pressure; The first and second inflow valves are opened (the first and second outflow valves are closed) in the suction stroke in which the piston is moved backward, and the first and second inflow valves are opened in the exhaust stroke in which the piston is moved forward.
The outflow valve is opened (the first and second inflow valves are closed), and the fluid is guided from the second pressure chamber to the pressure accumulation chamber and the first pressure chamber, thereby causing the first outflow of the first pressure chamber. The pressure is discharged from the valve, and the pressure in the pressure accumulator is increased to a predetermined pressure or less before the internal pressure in the pressure accumulator reaches the internal pressure of the first pressure chamber or higher in the discharge stroke of the first and second pistons. In order to suppress
The fluid supply device is configured such that the valve of the pressure accumulating chamber is set to have a spring bias smaller than the spring bias of the first inflow valve, and the bias force is set to open at the predetermined pressure in the pressure accumulating chamber, A small amount of fluid can be sent out from the pressure chamber by the action of the piston and bellows of the chamber, and at this time, the action of the second pressure chamber (which creates negative pressure with respect to the first pressure chamber) causes the bellows to rolling is carried out constantly without being deformed, and the inflow valve of the first pressure chamber is unstable in order to feed the fluid pressurized in the second pressure chamber to the first pressure chamber. Also, by effectively flowing a certain amount into the first pressure chamber, it is possible to reliably supply a fixed amount.

Furthermore, even if the first pressure chamber and the second pressure chamber have different capacities, by interposing the pressure accumulation chamber between them, the fluid between the side pressure chambers can be adjusted and a smooth fluid supply system can be achieved. It has the characteristic that it can obtain the following.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the present invention apparatus applied to an inkjet printer. 16: Suction pressure chamber, 17: Pressure chamber, 18: Constant flow rate discharge pressure chamber, 43: Pressure accumulation chamber provided corresponding to pressure chamber 17, 32, 41, 50: Inflow valve mechanism, 33, 42 ，
53: Outflow valve mechanism, 52: Communication path between the pressure chamber 1B and the pressure accumulation chamber 43.

Claims (1)

[Scope of Claims] 1. A first pressure chamber having holes for fluid inflow and outflow, a first piston that moves forward and backward with respect to the first pressure chamber, and the first pressure A first bellow, which seals the gap between the piston and the wall of the first pressure chamber housing the piston on the side of the chamber where the piston is located, and which rolls as the piston moves; A first inflow valve and a first outflow valve to which a constant biasing force is applied by a spring, which open and close the outflow hole in response to the forward/backward movement (suction/exhaust) movement of the first piston; a second pressure chamber having an inflow/outflow hole, adjacent to the first bellows, coaxially with the first pressure chamber, and having a larger diameter than the first pressure chamber; a second piston that moves forward and backward with respect to the second pressure chamber, the second piston having a diameter larger than that of the first piston, the second piston having one end connected to the first piston and disposed on one axis; A second piston that seals a gap between the second piston and the wall of the second pressure chamber housing the piston on the side where the second piston of the second pressure chamber is located and rolls as the piston moves. a second inflow valve and a second outflow valve on which a certain force is applied by a spring, which opens and closes the fluid inflow/outflow hole in response to the movement of the second piston; a reciprocating drive source connected to the other end of the second piston; an inflow hole connected to a second outflow valve of the second pressure chamber, and an outflow hole connected to the first pressure chamber; a pressure accumulation chamber connected to the first inflow valve of the chamber, and another communication hole communicating with the outside of the pressure accumulation chamber;
a valve that is always closed when the pressure is energized by the pump and opens when the pressure in the pressure accumulation chamber rises above a predetermined pressure; In the discharge stroke in which the first and second inflow valves are opened (the first and second outflow valves are closed) and the piston is advanced, the first and second
Opening the outflow valve (closing the first and second inflow valves) leads the fluid from the second pressure chamber to the pressure accumulation chamber and the first pressure chamber to cause the first outflow from the first pressure chamber. The pressure is discharged from the valve, and the pressure in the pressure accumulator is increased to a predetermined pressure or less before the internal pressure in the pressure accumulator reaches the internal pressure of the first pressure chamber or higher in the discharge stroke of the first and second pistons. In order to suppress this, the fluid supply device is characterized in that the valve of the pressure accumulation chamber is set to be smaller than the spring bias of the first inflow valve, and the bias force is set to open at the predetermined pressure in the pressure accumulation chamber. .