Electromagnetic pump

• US 4,021,152 A
• Filed: 05/10/1976
• Issued: 05/03/1977
• Est. Priority Date: 12/06/1974
• Status: Expired due to Term

• Current Assignee: Taisan Industrial Company Limited
• Original Assignee: Taisan Industrial Company Limited
• Inventors: Toyoda, Akira
• Primary Examiner(s): Schwadron, Martin P.
• Assistant Examiner(s): Hershkovitz, Abraham
• Application Number:
  US05/685,075
• Time in Patent Office: 358 Days
• Field of Search: 417/311, 417/417, 417/505, 417/568, 251/141
• US Class Current: 264/209.1
• CPC Class Codes: F04B 17/042 the solenoid motor being separated from the fluid flow
• CPC Class Codes: F04B 49/24 Bypassing

Abstract

An electromagnetic pump of the reciprocating type comprising a relief valve mechanism adapted to minimize the magnitude of pulsations of the fluid delivered by the pump and at the same time to act as a pressure accumulator. The relief valve mechanism comprises a pressure adjusting cylinder maintained in communication with the outlet side of the pump, a spring-loaded balancing plunger slidably mounted in the pressure adjusting cylinder, and a pressure adjusting screw adjustably mounted in the mechanism for regulating the biasing force of the spring so as to adjust the pressure applied by the spring to the balancing plunger to any level as desired. The pressure adjusting cylinder is formed therein with a relief port through which communication can be maintained between the outlet side of the pump and the suction side of the pump when a rise in the delivery pressure of the pump causes the pressure adjusting plunger to move rearwardly a predetermined distance against the biasing force of the pressure adjusting spring, whereby the delivery pressure of the pump can be maintained at a predetermined level at all times by spilling off the excess fluid from the pressure adjusting cylinder through the relief port.

Claims

1. An electromagnetic pump comprising a pump body, a cylinder, a pressure chamber, a suction valve and a discharge valve communicating with the pressure chamber, an electromagnetic coil mounted concentrically with an extension line of the longitudinal axis of said cylinder, a plunger case disposed within said electromagnetic coil, a delivery plunger and an electromagnetic plunger fitted in said cylinder and said plunger case, respectively, for reciprocating sliding movement and in abutting engagement with each other, said plungers being retained in pressure engagement between springs, characterized by a pressure adjusting cylinder provided within said pump body and including means communicating said pressure adjusting cylinder with the suction and delivery sides of the pump, a pressure adjusting plunger fitted within said pressure adjusting cylinder for reciprocating sliding movement and with an extremely small clearance between the outer diameter of the pressure adjusting plunger and the inner diameter of the pressure adjusting cylinder in a range where the sliding movement thereof is not prevented, said pressure adjusting plunger having at the top end thereof a valve body which engages a valve seat at an end of a passage connecting the delivery side of the pump with the pressure adjusting cylinder to thereby constitute a check valve, and said pressure adjusting plunger also having a shoulder portion at the top end thereof to thereby constitute a variable orifice relief throttle valve in the form of piston-valve together with a relief port perforated through the side wall of said pressure adjusting cylinder, said pressure adjusting plunger having said check valve and said relief throttle valve constituted separately, a pressure adjusting spring biasing the pressure adjusting plunger so as to close said check valve and said relief throttle valve, whereby said check valve is first opened in a process of rising in pressure in said passage after operation of the pump and on exceeding a predetermined pressure, said variable orifice relief throttle valve operates to adjust the opening degree of the orifice and relief port to thereby control the amount of leak from the delivery side of the pump through said passage, past said check valve and through said relief port so that the delivery pressure of the pump may be maintained at predetermined value, whereas from the time said check valve is opened till immediately before said variable orifice relief valve is opened, the pressure adjusting plunger moves in reciprocating movement by the extension and contraction of the pressure adjusting spring to thereby level the delivery pulsation of the pump and operate as an accumulator performing a pressure accumulating action.

2. An electromagnetic pump as set forth in claim 1, characterized in that the relief port of said variable orifice mechanism is located in a position below the suction valve of the pump, and a return duct is formed in the pump body to return the excess liquid under pressure from said relief port into the inlet side of the suction valve of the pump, said return duct being of a relatively small cross-sectional area and extending upwardly, so that the air bubbles contained in the excess liquid under pressure flowing through said return duct may be separated and converted into comminuted form, and returned to said suction side without accumulating and stagnating the air bubbles, and a suction joint connected to the inlet side of the pump body is formed therein with a small bore-like suction duct having the smallest cross-sectional area out of the passages at the suction side and a relatively long length, whereby a flow resistance can be imparted to the liquid flowing through said suction duct to cause more decrease in pressure between the duct and the suction valve, so that the excess liquid under pressure from the return duct and the liquid staying in the plunger case and the lower spring chamber can be drawn easily and quickly into the suction valve to thereby reduce or eliminate the vapor lock and any resistance against the operation of the electromagnetic plunger due to said liquid.