Information
-
Patent Grant
-
6234361
-
Patent Number
6,234,361
-
Date Filed
Friday, October 22, 199924 years ago
-
Date Issued
Tuesday, May 22, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
This pump dispenser has a piston with a central inlet opening connected to a tubular piston stem. A one-piece plastic check valve insert comprises a rim secured to the piston around the inlet opening and a hub which selectively seals the opening. The rim and hub are resiliently connected by zig-zag spokes.
Description
FIELD OF THE INVENTION
This invention relates to a pump dispenser of the type sometimes called a “trigger sprayer” in which the piston reciprocates vertically and is provided with a downward tubular inlet stem connected to an opening in the piston head. Liquid passes through the tubular stem and opening into the cylinder chamber. More specifically, this invention relates to the structure of the piston and an inlet check valve insert installed on such a piston and adapted to close the opening.
BACKGROUND OF THE INVENTION
The prior art, of course, is replete with varieties of manual pump dispensers adapted to pump liquid out a discharge orifice from a container on which the dispenser is mounted. One variety of such a dispenser is shown in the McKinney U.S. Pat. No. 4,161,288 in which the piston comprises a tubular inlet stem leading up to an opening in the piston head through which liquid passes into the pumping chamber. The piston seal is in the form of a plastic insert which seals the piston to the cylinder wall. The seal includes a central check plug aligned with the opening by webs integral with the piston seal and plug.
When the piston is raised by the trigger, the central plug seats on the opening blocking exit of the liquid back through the inlet. It raises on the downstroke to permit liquid to flow into the chamber.
Other check valves on the piston have included a steel ball operable in a special chamber and small enough to raise to permit passage of liquid on the downstroke, but dropping to close the tubular stem on the upstroke.
SUMMARY OF THE INVENTION
The invention is defined in the claim language. To be brief, the invention is a pump dispenser comprising a cylinder and piston assembly. The assembly is defined by a piston head and a tubular downward stem adapted to pass liquid up through an opening in the center of the piston head and into the cylinder chamber. A plastic check valve insert is installed in the upper side of the piston head. It comprises a one-piece molded wheel-like element including a securing rim fitting into an annular trough in the piston head, a central hub adapted to valve off the opening at the top of the tubular stem and a plurality of zig-zag spokes connecting the rim to the hub. These zig-zag spokes may each be in the form of arcuate portions concentric with the axis of the piston and inner and outer radial portions integral with the ends respectively of the arcuate portion.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and features of the invention will be clear to those skilled in the art from a review of the following specification and drawings, all of which present a non-limiting form of the invention. In the drawings:
FIG. 1
is a sectional view of a pump dispenser embodying the invention.
FIG. 2
is an enlarged exploded fragmentary view in section of the pump and check valve.
FIG. 3
is a greatly enlarged top plan view of the check valve, and
FIG. 4
is a sectional view of the check valve taken on the line
4
—
4
of FIG.
3
.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A pump dispenser embodying the invention is shown in FIG.
1
and generally designated
10
. It comprises a lower body portion
12
and a body cover
14
. Integral with the body portion is the inverted-cup-shaped cylinder
16
, the lower end of which is open.
From the upper end of the cylinder a delivery tube
18
extends forward to a nozzle fitting
20
. The fitting carries an operative discharge check valve
22
as described, for instance, in the U.S. Pat. No. 4,313,568 which issued Feb. 2, 1982 to Joseph Shay and which is assigned to the assignee of the present application. The fitting and valve are enclosed in a nozzle cap
24
which, depending on its position, controls the form of discharge, i.e. stream, spray, etc. The discharge path includes the usual swirl chamber and orifice
26
.
The lower body portion
12
is secured to the upper end of the spool-like retainer
28
which has a central opening
29
. The pump piston is generally designated
30
and is operatively disposed in the cylinder
16
. It includes a tubular stem
32
which extends through the opening in the retainer and which is coupled to a downward dip tube
33
. The retainer has an outward flange
34
which holds captive a closure
36
rotatable thereon.
A basket-shaped spring
38
of resilient plastic is centrally secured to the lower end of the tubular stem
32
by an inner ring
40
as described in U.S. pending patent application Ser. No. 09/298,596 filed Apr. 23, 1999 by Kenneth S. Bloom and assigned to the assignee of the present application. The spring
38
is formed with an outer ring
42
and in use the flange
34
and the outer ring
42
are sealingly clamped to the finish F of a container (not shown).
In opposition to the spring
38
, the piston
30
is raised by finger pressure on the trigger
46
having the piston-raising arm
47
and pivoted to the lower body portion
12
.
Turning now to an essential of the present invention, the piston
30
comprises (FIG.
2
), aside from the tubular stem
32
, a piston head
50
. The head is provided with a thickened periphery
52
to sealingly engage the inner surface of the cylinder
16
. Formed internally on the head
50
is an upward central cylindrical boss
53
. The boss is formed with a central opening
54
surrounded by a bevelled annular seat
56
. The opening
54
communicates with the axial passage of the tubular stem
32
.
The boss
53
is provided on its exterior wall
58
with an annular wall formed with an outward circumferential rib
60
. Outward from the boss the piston head is formed with an annular wall
62
generally parallel to the wall
58
of the boss. Between them the walls
58
and
62
define an annular trough
64
.
As best shown in
FIGS. 2
,
3
and
4
, the inlet valve sealing means comprises a wheel-like insert
66
. The insert
66
is unitarily molded of a resilient plastic such as polyethylene. It comprises a central hub
68
having a downward frusto-conical valving surface
70
and a rim
72
to the lower end of which is formed an upward annular fin
74
. The inner surface of the rim
72
is formed with an inward rib
75
.
As shown in
FIG. 3
, the hub and rim of the insert are connected by a plurality of zig-zag spokes
76
, each of which, as shown in
FIG. 3
, comprises an arcuate portion
78
concentric with the axis of the insert. The ends of portion
78
are connected to inner and outer radial portions
80
,
82
respectively.
In assembly, the hub of the insert
66
is aligned with the seat
56
. The rim is aligned with the annular trough
64
(
FIG. 2
) and moved downward. As the rim is inserted into the trough, the rib
75
engages the outward rib
60
on the boss in interference fit. When the rim is pressed farther toward the “home” position, the ribs
75
and
60
pass each other resulting in a snap fit engagement. This securing is enhanced by the outward pressure of the annular fin
74
on the inwardly facing wall
62
of the piston head.
As a result of the structure described, the downwardly facing frusto-conical surface
70
of the hub
68
can engage the inner edge of the seat
56
to seal and block downward flow of liquid. When, during the downward stroke of the piston, a negative pressure is created in the cylinder chamber, the hub
68
will rise permitting liquid in the passage of the stem
32
to enter into the chamber around valving surface
70
. This raising of the hub
68
is made possible by the resilience of the spokes
76
, particularly the arcuate portions
78
thereof which flex to permit the hub to rise.
The operation of the pump dispenser described herein is similar to that of the aforementioned patent application Ser. No. 09/298,596. From the downward position of the piston, the trigger
46
, as shown in
FIG. 1
, may be pulled toward the closure
36
to raise the piston, forcing liquid in the cylinder chamber out delivery tube
18
and through the discharge check and the orifice
26
. When the trigger is released, the spring
38
pulls the piston downward, creating a negative pressure in the cylinder chamber and causing the hub
68
of the insert to raise off the seat
54
drawing liquid from the tubular stem upward into the chamber. Upon the next retraction of the trigger
46
, the piston will raise, causing the liquid, as well as the natural resilience of the spoke
78
, to seat the bottom side of the hub
68
on the seat
54
, driving the contents of the cylinder out the delivery tube
18
.
As can be seen, the structure of the present invention permits the construction of an all-plastic pump dispenser, such that it may be processed for re-use of the plastic in a well-known manner. At the same time, the sealing member provides reliable operation for the discharge check valve. As compared to a ball-type check valve, the present invention reduces cost by removing metal, minimizing corrosion, and thereby further makes possible the use of the pump dispenser with corrosive liquids.
An advantage of having the piston seal a separate piece from the sealing valve is that these parts may be of different plastics respectively to optimize the characteristics of both parts, that is, the sealing valve to function best must be of a relatively more resilient plastic, such as medium density polyethylene, while the piston
50
peripheral seal engaging the cylinder must be of a relatively stiffer plastic, such as a high density polyethylene. The present invention enables such selection.
Variations in the invention are possible. Thus, while the invention has been shown in only one embodiment, it is not so limited but is of a scope defined by the following claim language which may be broadened by an extension of the right to exclude others from making, using or selling the invention as is appropriate under the doctrine of equivalents.
Claims
- 1. A pump dispenser comprising:a. a cylinder, and b. a piston assembly operable in the cylinder and comprising 1) a piston bead having a peripheral seal sealingly engaging the inside surface of the cylinder, the head having a central axially extending boss with an axial opening surrounded by an annular seat, the boss having an outward annular rib, the head having an inward facing wall outward from the hub defining an annular trough, 2) a tubular stem integrally formed with the piston head on the opposite side from the hub and adapted to deliver liquid to the central opening in the piston head, 3) an integrally formed inlet sealing valve insert molded of a resilient plastic attached to said piston head, said sealing valve insert comprising: i. a peripheral rim portion secured in the annular trough, ii. a hub portion movably aligned with the seat of said bore, said hub portion including a sealing surface which selectively is disposed in a liquid-tight seal position with the seat, and iii. a plurality of resilient spokes connecting the rim and the hub.
- 2. A pump dispenser as claimed in claim 1 wherein the spokes are zig-zag in configuration, each comprising an arcuate portion concentric with the axis of the insert and radial portions connecting the opposite ends of the arcuate portion to the rim and the hub respectively.
- 3. A pump dispenser as claimed in claim 1 wherein the boss has an outward rib and the rim has an inward rib and the ribs interfere with each other in snap installation of the rim in the annular trough.
- 4. A pump dispenser as claimed in claim 1 wherein the rim has an outward and upward annular fin engaging the inward facing wall.
- 5. A method of making a piston/inlet check assembly comprising the steps of:a. providing a piston comprising a piston head and a tubular stem connected to the head at a central opening in the piston head, the head having an annular trough concentric with the axis of the opening and surrounding the opening with an outward rib on an inward wall of the trough, b. providing a wheel-like inlet valve insert comprising a rim having an inward peripheral rib, a central hub aligned with the opening, and a plurality of resilient spokes connecting the hub and rim, and c. aligning the hub over the opening and pressing the rim into the annular trough so that the ribs on the piston and on the rim snap past each other to secure the insert to the piston.
US Referenced Citations (9)