JPS59182743A - Rotary pump - Google Patents

Abstract

PURPOSE:To obtain a rotary pump for an ink jet recorder, which is capable of smoothly recovering liquid at the restart of operation and also of returning liquid in a liquid trap to a pressure chamber at the stoppage of operation, by providing the liquid trap between the pressure chamber and a discharge port. CONSTITUTION:A liquid trap 12 is provided between a pressure chamber 8 and a discharge port 14. When a rotary piston 5 is turned one time along the inner wall of the pressure chamber 8 by a motor 1, the inlet port 9 side of the pressure chamber 8 is closed, the discharge port 14 is opened, the volume of the pressure chamber on the discharge port side is reduced, and a fluid is pushed out of the discharge port, the fluid is temporarily stayed in the liquid trap 12. EFFECT:When the rotary pump is temporarily stopped, ink in the liquid trap 12 is again returned to the pressure chamber 8 under its own weight, and operation is made under normal sending pressures at the restart of operation. Even when gases alone enter the pump, priming water is unnecessary because liquid is returned from the liquid trap by stopping the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a fluid supply pump in an inkjet recording device, and more particularly, to a rotary pump for pumping a gas-liquid mixed fluid in a fluid supply system of an inkjet recording device. .

Generally, in charge control deflection type inkjet recording devices, the ink that does not contribute to recording is captured in the gutter, collected in the ink tank, and used again. The amount of ink used for recording is about a few percent of the total amount, and the other ink is not used and is collected into an ink supply and recovery system via a gutter, and circulated in a certain circulation loop. At this time, the ink and air are sucked into the ink trapping gutter, and the gas-liquid mixed ink is collected by the collection pump and used again.

In such conventional inkjet recording apparatuses, it is already well known that, for example, a vane-type rotary pump is used as an ink supply pump. However, when the nozzles of the ink jet head become clogged and repairs are performed or regular maintenance is required, the recovery pump may be activated without ejecting ink from the nozzles, and in this case, the pump Since only air enters the pump, there is no liquid in the pressure chamber of the pump. Therefore, the liquid recovery ability is reduced, and even if an attempt is made to recover ink, it will not be possible. Furthermore, in the case of conventional rotary pumps, the entire pump can be made smaller and cheaper because it does not require a valve mechanism, but on the other hand, it is possible to make the entire pump smaller and cheaper. If this happens, air will leak from the gap between the piston and the inner wall of the pump body, reducing the pumping pressure.
It becomes unusable. Furthermore, unless a small amount of liquid, generally called priming water, is injected into the gap in the inner wall portion, the device cannot be returned to a usable state.

Purpose The present invention has been made in view of the above-mentioned actual situation, and the present invention has been made in view of the above-mentioned circumstances. The primary purpose is to allow the liquid in the reservoir to return to the pressure chamber once operation has stopped, allowing the pump to operate at normal pumping pressure when operation resumes. The second purpose is to obtain a normal liquid recovery ability again without injecting priming water by causing the liquid in the liquid reservoir to enter the pressure chamber when the operation is stopped even if the liquid stops flowing.

Eyebrow Knee 1 The configuration of the present invention will be described below based on examples.

FIG. 1 is an exploded perspective view for explaining one embodiment of the present invention, in which 1 is a motor that drives a rotary pump, 2 and 3 are gears that transmit the rotational force from the motor 1, and 4 is a shaft, 5 is a rotary piston (eccentric cam) directly connected to the shaft 4, 6 is a vane, 7 has one end fixed to a fixed wall of the rotary pump body (not shown), and the other end presses the vane 6. 8 is a pressure chamber, IO is an inflow pipe for introducing fluid into the pressure chamber 8 from an inlet 9, 11 is a connecting pipe, 12 is a liquid reservoir, 13
is a discharge pipe that discharges fluid from the discharge port 14 to the outside of the rotary pump.

When the shaft 4 is rotated by the motor 1 via the gears 2 and 3, the rotary piston 5, which is eccentrically connected directly to the shaft 4, rotates along the inner wall of the pressure chamber 8.

The space C defined by the rotary piston 5, vane 6, and pressure chamber 8 increases or decreases as the rotary piston rotates. When the tangent between the rotary piston and the pressure chamber reaches the tip position 6a of the vane, the volume of the pressure chamber on the inlet side (IN side) connected to the inlet 9 begins to increase, and fluid is drawn from the inlet. Inhale. When the rotary piston rotates once, the inlet side of the pressure chamber closes and the outlet side (OUT side) opens, and the volume of the pressure chamber on the outlet side begins to decrease. As a result, fluid is pushed out from the discharge port 14.

When using this type of pump, a gap is created between the pressure chamber and the rotary piston.

Fluid leaks from there. At this time, the viscosity of liquid and gas is significantly different, and the amount of leakage is larger for gas.

Therefore, the operating efficiency of the pump can be maintained better by keeping the inner wall of the pressure chamber of the rotary pump body wet.

In the ink recovery rotary pump according to the present invention, a liquid reservoir is provided between the pressure chamber 8 and the discharge port 14, so that the ink liquid temporarily accumulated in the liquid reservoir returns to the pressure chamber when the pump stops operating.

FIG. 1 shows an embodiment in which a liquid reservoir 12 is provided above the pressure chamber 8. The liquid reservoir 12 and the pressure chamber 8 are connected through a connecting pipe 11, and when the pump stops operating, the ink is removed. falls towards the pressure chamber located below due to its own weight.

FIG. 2 is a perspective view of essential parts showing another embodiment of the present invention, in which parts having the same structure and function as those in FIG. 1 are given the same reference numerals. In FIG. 2, a liquid reservoir 22 is provided in a space in which a spring 7 that presses the vane exists, and the pressure chamber 8 and the liquid reservoir 22 are communicated through a connecting pipe 21. In this embodiment, when the pump stops operating, liquid permeates from the liquid reservoir toward the pressure chamber through the gap between the vanes and the vane sliding part by capillary action.

FIG. 3 shows the operation of a rotary pump with a rotary piston 5, a pressure chamber 8 and a vane 6 by rotation of the shaft, in order to explain the operating principle of the embodiment according to the invention shown in FIGS. 1 and 2. It shows changes in the positional relationship viewed from the top over time. As is clear from FIG. 3, the rotary piston 5 attached to the shaft 4 rotates while contacting the inner wall of the pressure chamber 8. The vane 6 is pressed against the rotary piston by the pressing force of a spring 7 whose one end is fixed to the fixed wall 31, and repeats back and forth movement. When the motor rotates the shaft, the volume of the space formed by the vane, rotary piston, and wall of the pressure chamber increases, and liquid is sucked in from the inlet side. When the rotary piston rotates once, the liquid in the pressure chamber is separated from the inlet side and pushed out from the outlet side. In this way, a rotary pump completes one stroke in one rotation, but there are two partitioned spaces, and when the liquid in one space is being pushed out from the discharge port, the liquid in the other space is pushed out from the inlet. Since the liquid is being sucked in from the side, the -rotation-stroke operation is essentially repeated.

As is clear from the above explanation, according to the present invention, once the operation of the rotary pump stops, the liquid that has entered the liquid reservoir returns to the pressure chamber, and when the operation resumes, the pump returns to the normal pumping pressure. Furthermore, even if only gas enters the pump, when the operation is stopped, the liquid in the liquid reservoir will enter the pressure chamber, allowing normal operation to resume without priming water. A rotary pump can be implemented to obtain liquid recovery capability.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view for explaining one embodiment of the present invention, FIG. 2 is a perspective view of main parts showing another embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 2 is a diagram illustrating the operating principle. 1... Motor, 2, 3... Gear, 4... Shaft, 5... Rotary piston, 6... Vane,
7... Spring, 8... Pressure chamber, 9... Inflow port, 10... Inflow pipe, 11.21... Connection pipe, 12,
22...Liquid reservoir, 13...Discharge pipe, 14...Discharge port, 31...Fixed wall. Patent applicant: Ricoh Co., Ltd. Figure 1 (A) 31,) Figure 3

Claims (1)

[Claims] A rotary pump for pumping gas-liquid mixed fluid under pressure, characterized in that a liquid reservoir is provided between a pressure chamber and a discharge port, and the liquid in the reservoir returns to the pressure chamber when the operation is stopped.