| 摘要 |
PURPOSE:To lessen load at a piston rod sliding portion by letting a lubricating component flow out from the rear of a packing at pressure larger than the discharge pressure of a piston during the advance of the piston. CONSTITUTION:During the advance of a piston rod 10, the pressure of discharging a raw material component is increased in a port 15. A valve device 40 which is caused to fluctuate by such pressure is disposed in a connecting path 33 connected to a passage 32 for a lubricating component, whereby the lubricating component can be forced out from the rear of a packing 20 corresponding to the discharge pressure in the port. As a piston rod 42 is located in the rear of a piston 41, the sectional area is decreases that much, so that the lubricating component is forced out from the rear of the packing 20 at pressure larger than the discharge pressure of a main body piston 10. Accordingly, the frictional force applied to the packing 20 can be reduced remarkably. |
