Modular, adjustable force, all-polymer helical biasing member and pump dispenser incorporating same
A biasing member for use in reciprocating dispenser pumps is contemplated. The member is made completely of polymeric materials and is suitable as a direct replacement for metallic coil springs. The biasing member includes spiral shape defined by inner and outer helix traces, with a series of perforations provided along one or both of those traces. These perforations, in conjunction with thinned channels, the size and shape of holes, and the size and shape of apertures, all cooperate to allow for a spring with sufficient resilience and greater spring force in comparison conventional, all-polymer biasing members.
1. An all-polymer, reciprocating dispenser pump comprising:
an actuator having a stem;
a pump body configured to receive the stem; and
a biasing member interposed between the actuator and the pump body to urge the actuator away from the pump body, the biasing member comprising a plurality of modular units arranged in a stack and each having a central aperture sized to coaxially receive the stem; wherein each modular unit includes an upper radial flange, a lower radial flange, a wall section, a central aperture, and an outer helix trace radially offset from an inner helix trace, with both the outer helix trace and the inner helix trace spiraling round a central axis of the biasing member from a bottom edge to a top edge so as to impart a corrugated surface to the wall section; and wherein the upper radial flange of each modular unit is configured to be received in the lower radial flange, or to be abutted with the upper radial flange, of an adjacent modular unit in the stack.
2. The dispenser pump of claim 1 , wherein a minimum radius of the outer helix trace, as measured within a horizontal plane of the biasing member, is larger than a maximum radius of the inner helix trace in any horizontal plane of the biasing member.
3. The dispenser pump of claim 1 , wherein the outer helix trace remains offset from the inner helix trace at a constant axial distance.
4. The dispenser pump of claim 1 , wherein a plurality of perforations regularly interrupt one or both of the outer helix trace and the inner helix trace.
5. The dispenser pump of claim 1 , wherein coupling formations are formed on a horizontal surface of the upper radial flange and/or the lower radial flange of each modular unit.
6. The dispenser pump of claim 5 , wherein the coupling formations include at least one of radially aligned ribs, an inner circular wall, and an outer circular wall.
7. The dispenser pump of claim 1 , wherein coupling formations are formed on a vertical surface of an axially extending wall from the upper radial flange and/or from the lower radial flange of each modular unit.
8. The dispenser pump of claim 7 , wherein the coupling formations include at least one of an axially extending sidewall, the coupling formations formed in an outer facing of the axially extending wall, and the coupling formations formed in an inner facing of the axially extending wall.
9. The dispenser pump of claim 1 , wherein cooperating, coupling formations are provided on the upper and lower flanges of each modular unit, the cooperating, coupling formations configured so that a lower flange from a first unit either nests in an upper flange of a second unit or abuts a lower flange of the second unit.
10. The dispenser pump of claim 9 , wherein all of the modular units are provided in a nested relationship or in an abutting relationship.
11. The dispenser pump of claim 9 , wherein three modular units are provided in the stack in a mixed relationship.
12. The dispenser pump of claim 1 , wherein three modular units are provided in the stack.
13. A method of adapting the spring force of an all-polymer biasing member dose size of an all-polymer dispenser pump, the method comprising: providing a plurality of modular spring units, each spring unit having a central aperture, an upper radial flange, a lower radial flange, a central aperture, and an outer helix trace radially offset from an inner helix trace, with both the outer helix trace and the inner helix trace spiraling round a central axis of the biasing member from a bottom edge to a top edge so as to impart a corrugated surface to the wall section; and coupling the modular spring units so as to form a biasing unit having a specific and differing spring force dependent upon whether the modular spring units are arranged in a nest relationship, an abutting relationship, or in a mixed relationship, and positioning the biasing unit between a pump body and around a stem of an actuator head so as to urge the actuator head away from the pump body at a desired spring force.