Relief valve

Patent metadata

Field	Value
Publication number	US-9435448-B2
Application number	US-201214110626-A
Country	US
Kind code	B2
Filing date	May 31, 2012
Priority date	Jun 8, 2011
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

A relief valve configured such that a plunger configured to be pushed forward by an elastic member to block communication between an inflow opening and an outflow opening moves rearward by an increase in pressure of the inflow opening against an elastic force of the elastic member to cause the inflow opening and the outflow opening to communicate with each other; and a piston configured to push a rear end of the elastic member forward moves forward by the increase in the pressure of the inflow opening to compress the elastic member, the elastic member includes a first elastic member and a second elastic member arranged in series, and the second elastic member has a smaller elastic constant than the first elastic member.

First claim

The invention claimed is:

1. A relief valve configured to adjust relief pressure, the relief valve comprising:
a plunger configured to be pushed forward by an elastic unit to block communication between an inflow opening and an outflow opening, the plunger being moved rearward by an increase in pressure of the inflow opening against an elastic force of the elastic unit to cause the inflow opening and the outflow opening to communicate with each other; and
a piston configured to push a rear end of the elastic unit forward, the piston being moved forward by the increase in the pressure of the inflow opening to compress the elastic unit, wherein:
the elastic unit includes
a first elastic member and a second elastic member arranged in series, and
a spring seat inserted around the plunger so as to be interposed between the first elastic member and the second elastic member;

the second elastic member has a smaller elastic constant than the first elastic member and is arranged between the spring seat and one of the plunger and the piston;
said one of the plunger and the piston includes a large portion spreading radially outward;
the plunger is inserted through the spring seat so as to be movable relative to the spring seat;
the spring seat is formed in a cup shape having an opening end portion; and
the opening end portion of the spring seat (i) opposes the large portion, (ii) is located away from the large portion by a predetermined maximum compression length, and
(iii) contacts said one of the plunger and the piston to restrict a compression length of the second elastic member such that the compression length of the second elastic member becomes equal to or less than the predetermined maximum compression length.

2. The relief valve according to claim 1 , wherein:
a maximum relief pressure is mainly set by the first elastic member; and
the relief pressure before the piston moves forward is mainly set by the second elastic member.

3. The relief valve according to claim 1 , wherein a stopper configured to stop the rearward movement of the plunger at a predetermined most rearward position is provided at a case in which the plunger is housed.

4. The relief valve according to claim 1 , wherein a ratio K1/K2 that is a ratio of an elastic constant K1 of the first elastic member to an elastic constant K2 of the second elastic member is from 5 to 20.

5. The relief valve according to claim 1 , wherein:
a liquid chamber in which the elastic unit is housed communicates with the outflow opening;
the piston includes a first slide portion that liquid-tightly slides on an inner hole of a case;
a rear portion of the plunger is slidably, fittingly inserted in a slide hole formed at the piston along a central axis of the piston;
the plunger includes a through hole through which pressure liquid is introduced from the inflow opening to a rear side of the plunger;
a third liquid chamber is formed by the through hole and a space which is located at a rear portion of the slide hole and to which the plunger does not reach;
the piston includes a rearward acting surface and a forward acting surface located at a rear side of the first slide portion;
the third liquid chamber and a first liquid chamber to which the rearward acting surface faces communicate with each other through a communication hole formed at the piston;
the third liquid chamber and a second liquid chamber to which the forward acting surface faces communicate with each other through another communication hole formed at the piston; and
the piston moves forward by a difference between a forward acting force applied to the forward acting surface by the pressure liquid and a rearward acting force applied by the pressure liquid to a bottom surface of the slide hole of the piston and the rearward acting surface.

6. The relief valve according to claim 5 , wherein:
an area of the forward acting surface is larger than a total of an area of the bottom surface of the slide hole and an area of the rearward acting surface; and
the difference between the forward acting force and the rearward acting force is generated by a difference between the area of the forward acting surface and the total of the area of the bottom surface of the slide hole and the area of the rearward acting surface.

7. The relief valve according to claim 5 , wherein:
a pressure difference is generated between front and rear sides of each of the communication holes by the difference between the forward acting force and the rearward acting force; and
the piston moves forward while the pressure liquid flows through the communication holes.

Assignees

• Matsuo Masahiro
• Nasu Hirokazu
• Kawasaki Heavy Ind Ltd

Inventors

• Matsuo Masahiro
• Nasu Hirokazu

Classifications

• F16K17/065

  with differential piston · CPC title

• F16K17/044 Primary

  with more than one spring · CPC title

• Y10T137/7794

  With relief valve · CPC title

• F16K17/04 Primary

  spring-loaded · CPC title

• F16K17/06 Primary

  with special arrangements for adjusting the opening pressure · CPC title