JPS58108150A - Quantitative flow rate pump - Google Patents

Abstract

PURPOSE:To maintain ink flow rate constant, free from the influence of temperature and ink viscosity by employing different kinds of valves with different temperature characteristics for suction and discharge valves. CONSTITUTION:A suction valve 24 for sucking ink of a reciprocally driven quantitative flow rate pump used to supply the ink to an ink jet head is so arranged that a metal ball valve disc 4 is pressed against a rubber valve seat 3 with a compression spring 5, whereas a discharge valve 25 for sending the ink to the ink jet head is composed of a metal valve seat 9, a valve seat formed by attaching rubber material 11 to a resin or metal disc 10, and a compression spring 12 used to press the valve disc against the valve seat 9. Then a piston 21 within the cylinder 22 is moved toward the direction indicated by the arrow P to cause the inside of a pump chamber 23 to have suction power to introduce the ink in the pump chamber 23 by closing a valve 25 and opening a valve 24. Subsequently, the piston 21 is moved in the direction shown by the arrow Q to cause the ink to be discharged by closing the valve 24 and opening the valve 25.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant flow pump for supplying ink to a head in an inkjet recording apparatus, and in particular, the present invention relates to a constant flow pump for supplying ink to a head in an inkjet recording apparatus, and in particular, the present invention relates to a constant flow pump for supplying ink to a head in an inkjet recording apparatus. This relates to flow pumps.

Conventionally, a reciprocating method involves reciprocating a piston within a cylinder using inlet suction and return screws, or by cam action driven by a motor, drawing ink from an ink tank into a pump chamber, and ejecting the ink to supply it to an inkjet head. Driven constant flow pumps are used, and the types of suction and discharge valves in these pumps vary widely.

Figure 1 shows a typical example. In the French model, both the valve seat 1 and the spherical valve body 2 are made of metal, so they have little effect on temperature and ink viscosity. However, if the fitting part between the valve body 2 and the valve seat l is not finished with high precision, leaks will occur, and even the slightest amount of dust or minute scratches will significantly reduce the valve function.

FIG. 1(B) shows a spherical valve body 4 mounted on a valve seat 3 made of rubber material.
is pressed by a compression spring 5. Therefore, even if minute dust or dirt gets on the valve part, the elasticity of the valve seat 3 can prevent the valve function from deteriorating. but,
Changes in temperature cause changes in the elasticity of the rubber, and as a result, the second
As shown at 03) in the figure, the ink flow rate changes with temperature changes.

In FIG. 1(C), the valve body 7 is disc-shaped and made of metal together with the valve seat 6, and the two are pressed together by a compression spring 8. Like type (4), this type requires high precision in the busy valve part, and is also affected by the viscosity of the ink, which changes with temperature changes, as shown in (0) in Figure 2. Note that the relationship between temperature and viscosity is shown in FIG.

) in FIG. 1 consists of a metal valve seat 9, a valve body made of a resin or metal disk lO with a rubber material 11 attached, and a compression spring 12 that presses the valve body against the valve seat 9. Ori,
The part accuracy may be lower than type (B), but the 21st! ! As shown in J, it is affected by changes in ink viscosity in the same way as type Q.

As described above, each type of pump has its own drawbacks, but since conventional pumps use the same type of suction valve and discharge valve, the flow rate of ink is affected by changes in turbidity and It was easy to fluctuate due to the influence of the viscosity, which changes depending on the temperature.

In order to eliminate the drawbacks of the above-mentioned conventional example, the present invention adopts the (B) type shown in Fig. 1 for the suction valve and the type (B) type for the discharge valve, thereby achieving the characteristics of the six valves. The purpose of this invention is to provide a constant flow pump that is skillfully combined to substantially eliminate the influence of temperature changes on ink flow rate and is inexpensive to manufacture. Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 4 shows an embodiment of the present invention, in which a piston 21 reciprocates within a cylinder 22, and this piston is driven by a combination of solenoid suction and a return spring, or by a cam action driven by a motor. Let's do it. A pump chamber 23 sucks ink from one side and discharges it to the other side. 2
Reference numeral 4 denotes an extension type suction valve shown in FIG. 1, and 11 is connected to an ink tank shown in FIG. 25 is a CD type discharge valve shown in FIG. 1, and is connected to an inkjet head (not shown). Now, when the piston 21 moves in the direction of arrow P, the pressure in the pump chamber 23 becomes negative, so the discharge valve 25 is closed and the suction valve 24 is opened to introduce ink into the pump chamber. Next, when the piston 21 moves in the direction of arrow Q,
The suction valve 24 is turned on, and the discharge valve 25 is opened to discharge ink and supply it to the inkjet head.

Since the suction valve 24 and the discharge valve 25 have the characteristics (B) and (B) shown in FIG. 2, respectively, with respect to temperature changes, these two characteristics cancel each other out, and the pump characteristics are as follows. As shown in Figure 5, #1
This will maintain a fairly flat flow rate characteristic.

As explained above, according to the present invention, by employing different types of valves with opposite temperature characteristics for the suction valve and the discharge valve,
We can provide a constant flow pump that maintains the ink flow rate at a constant level without being affected by temperature or ink viscosity.Moreover, since an elastic body is used for the valve seat or valve body, processing accuracy cannot be as strict. There is no need to do this, and there is an advantage that it can be constructed at low cost.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the configuration of various valves, Figure 2 is a diagram showing the relationship between temperature and flow rate of various valves, Figure 3 is a diagram showing the relationship between turbidity and ink viscosity, and Figure 4 is a diagram showing the relationship between turbidity and ink viscosity. The figure is a configuration diagram of a main part of an example of an embodiment of the present invention, and FIG. 5 is a diagram showing the relationship between the flow rate and the temperature of the same example. 3 ・・・・・・・・・ Valve seat, 4 ・・・・・・・・・
Spherical valve body, 5... Compression spring,
9... Valve seat, lO... Disk, 11... Rubber material, 12...
・・・・・・Compression spring, 21・・・・・・・・・
・Piston, 22...Cylinder, 23・
......Pump chamber, 24...Suction valve, 25...Discharge valve. Figure 1 + Al 18) (C) (D) Figure 2 Figure 3 4 Tomoshizuku N Figure 5

Claims (1)

[Claims] A reciprocating constant flow pump that supplies ink to an inkjet head is used to draw ink from an ink tank. The discharge valve includes a compression spring that presses the body against the rubber valve seat, and sends ink to the inkjet head. , a compression spring that presses the disc-shaped valve body against the metal valve seat.