US 3923427 A
A differential volume pump having a pair of flexible diaphragms in the housing thereof defining separate chambers each having inlet and outlet ports communicating therewith. A stop member is disposed about the periphery of one of the diaphragms so as to limit its movement toward one wall of the housing when the diaphragms are shifted by actuating means. The displacement achieved by reciprocating the diaphragms is less in the chamber having the stop member than the other chamber, thereby producing differential volume flow.
Description (OCR text may contain errors)
United States Patent Uyeda 1 Dec. 2, 1975 I 4] DIFFERENTIAL VOLUME PUMP 3,765,802 l0/l973 Leitermann et al. 417/52l  Inventor: Tim M. Uyeda, South San Gabriel, FOREIGN PATENTS OR APPLICATIONS Calif- 14,932 1906 United Kingdom 417/521  Assignee: International Telephone and Telegraph Corporation, New York, Prlmary Exam1nerW1ll1am L. Freeh Assistant Examiner-O. L. Sess1ons Attorney, Agent, or Firm-Thomas L. Peterson  Filed: Sept. 16, 1974  Appl. No.: 506,030 ABSTRACT A differential volume pump having a pair of flexible 52 us. Cl. 417/534; 92/48; 92/49 daphragms hereof defmmg 2 chambers each having mlet and outlet ports communi-  Int. Cl. F04B 39/10 h A b d lb h  Field of Search 417/521, 534-537; mp "T pose P FF per1phery of one of the dlaphragms so as to limit 1ts 92/48, 49, 64, 97, 100
movement toward one wall of the housing when the  References Cited d1aphragms are shlfted by actuating means The d1splacement achieved by reciprocatmg the d1aphragms UNITED STATES PATENTS is less in the chamber having the stop member than 1,473,173 11/1923 Brinkerhoff 92/49 th other chamber, thereby producing differential vol- 2,839,086 6/1958 Engleberger.... 92/49 ume flow. 2,849,864 9/1958 Hill et al. i .1 92/49 3,244,396 4/1966 Miller 92/49 2 Claims, 2 Drawing Figures US. atent Dec. 2, 1975 Sheet 1 of 2 3,923,427
U.S. Patant Dec. 2, 1975 Sheet 2 of2 3,923,427
DIFFERENTIAL VOLUME PUMP BACKGROUND OF THE INVENTION The present invention relates generally to a diaphragm pump and, more particularly, to a differential volume diaphragm pump.
There are numerous applications for differential volume pumps. One application for such a pump is in a marine toilet for discharging toilet waste therefrom and pumping flush water into the toilet. A differential volume pump is required since the volume of waste and flush water which must be discharged from the toilet is greater than the volume of flush water delivered into the toilet. It is also necessary for this application of a differential volume pump that the pump be simple in operation and relatively low in cost. The purpose of the present invention is to provide such a pump.
SUMMARY OF THE INVENTION According to the principal aspect of the present invention, there is provided a differential volume pump comprising a housing having spaced front and rear flexible diaphragms therein. The space between the front diaphragm and the front wall of the housing forms a first chamber. The space between the diaphragms forms a second chamber. Inlet and outlet ports communicate with the chambers so that fluid may flow in separate flow paths through the chambers. Stop means is provided on the housing which extends inwardly in front of the rear diaphragm to limit forward movement of the diaphragm when the two diaphragms are moved together toward the front wall of the housing. Means are provided for moving the diaphragms in unison toward and away from the front wall. Because of the stop means, the second chamber, as well as the first chamber, will change in volume when the diaphragms move toward the front wall. The pump is constructed so that the change in volume of the first chamber is greater than that of the second chamber. Hence, during one stroke of movement of the diaphragms the change in volume and, hence, displacement of fluid, is greater in the first chamber than in the second chamber. By modifying the configuration of the stop means, the volume difference between the chambers may be altered.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinal sectional view through the pump of the present invention, shown somewhat schematically, with the diaphragms shown in their rearward most position; and
FIG. 2 is a partial sectional view similar to FIG. 1 but showing the diaphragms in their forward most position.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, there is illustrated the differential volume pump of the present invention, generally designated 10. The pump comprises a housing 12 containing a front flexible diaphragm l4 and a rear flexible diaphragm 16. The diaphragms may be forms of any suitable flexible material, and preferably an elastomer such as neoprene rubber. The front wall 18 of the housing is in the form of a rigid cupshaped plate. The outer peripheries of the diaphragms and the front wall 18 of the housing are connected in sealing engagement in a manner which will be described in detail later. The space between the front diaphragm 14 and the front wall 18 of the housing defines a front chambere 20 while the space between the diaphragms 14 and 16 defines a rear chamber 22. An inlet port 24 and outlet port 26 are connected to the front wall 18 so as to be in flow communication with the chamber 20. A second pair of inlet and outlet ports, designated 28 and 30, respectively, open in the rear chamber 22. The ports 28 and 30 could be connected to the rear diaphragm 16. Preferably, however, they are connected to a ring member 32 which is interposed between the outer peripheries of the diaphragms. An inlet check valve 34 is provided in the inlet port 24 and an outlet check valve 36 is provided in the outlet port 26. In addition, an inlet check valve 38 is provided in the inlet port 28 and an outlet check valve 40 is provided in the outlet port 30.
The cup-shaped front wall 18 of the housing is formed with an outwardly extending peripheral flange 42. The ring member 32 also has an outwardly extending flange 44. The outer periphery of the front diaphragm 14 is interposed between the flanges 42 and 44. A cover 46 may be mounted on the rear of the housing 12. This cover has an outwardly extending flange 48. The outer periphery of the rear diaphragm 16 is interposed between the flanges 44 and 48. Each flange has a configuration complementary to the other. Fastening elements 50 are mounted through the flanges and the outer peripheries of the diaphragms at spaced locations about the perimeter of the housing to secure the members together in sealing engagement.
A support plate 56 is positioned between the diaphragms 14 and 16. A second support plate 58 is mounted in front of the front diaphragm 14. A screw 60 extends through the central portions of the support plates. The end of the screw is threaded into a plunger 62 thereby clamping the front diaphragm 14 between the plates 56 and 58 and the rear diaphragm 16 between the rear plate 56 and the plunger. As a consequence, when the plunger 62 is shifted axially, the diaphragms will move in unison.
Actuating means, generally designated 64, is provided for shifting the plunger and therefore the diaphragms in the housing 12. The actuating means comprises a horizontally extending pivot rod 66 which is rotatably mounted on the cover 46. One end of the rod is bent upwardly to provide an actuating arm 68. A yoke 70 is fixedly attached to the rod 66 by means of a key 72 and a screw 74. The yoke includes a pair of legs' 76, only one being visible in the drawings, which extend downwardly on opposite sides of the plunger 62. Theplunger carries a horizontally extending pin 78 which is parallel to the pivot rod 66. The opposite ends of the pin 78 extend through slots 80 in the lower ends of the legs 76 to provide a lost motion connection between the yoke 70 and the plunger 62. An opening 82 is provided in the cover 46 for receiving the plunger 62 and the yoke 70. While the actuating means 64 has been shown as being mounted on a cover 46 connected to the housing 12, it will be appreciated that such means could be mounted on other structure than the housing, thus eliminating the cover 46. In either case, the rear diaphragm 16 forms the rear wall of the housing 12 of the pump. It will also be appreciated that the diaphragms 14 and 16 may be shifted by means other than a lever actuating mechanism. According to an im portant feature of the invention, the inner portion 84 of the ring member 32 extends inwardly and rearwardly at an angle to provide a stop for the rear diaphragm 16 limiting its forward movement upon movement of the diaphragm assembly toward the front wall 18 of the housing. This results in a change in volume of the rear chamber 22 during one stroke of movement of the diaphragm assembly.
In FIG. 1, the diaphragm assembly is shown in its rearward most position. To actuate the pump, the arm 68 is pivoted rearwardly causing the yoke 70 to shift the plunger 62 and diaphragms forwardly in the direction of the front wall 18 of the housing. Considering first the front diaphragm, during forward movement, liquid in 'the chamber is discharged out of the port 26 through the one-way check valve 36. When the actuating arm 68 is pivoted forwardly in the direction indicated by the arrow in FIG. 2, front diaphragm will move rearwardly from the front wall 18 of the housing thereby drawing liquid through the one-way check valve 34 in port 24 into the front chamber 20.
As the front diaphragm I4 is moved toward the front wall 18 of the housing by the actuating means 64, the
rear diaphragm 16 moves together with the front diaphragm as a unit. There would be no change in the volume of rear chamber 22 between the diaphragms during this movement except for the fact that the rear diaphragm engages the stop member 84, causing the volume of the rear chamber to increase. Actually, the diaphragms stretch a 'small degree during forward movement. This results in liquid entering the rear chamber through the check valve 38 in the inlet port 28. Movement of the diaphragm assembly away from the front wall 18 to the position illustrated in FIG. 1 causes the volume of the rear chamber to decrease thereby forcing liquid out of the chamber through the check valve 40 in the outlet port 30.
It is noted that the pump is constructed so that there is a greater change in volume in the front chamber than the rear chamber upon one stroke of movement of the diaphragm. Hence, there is greater displacement of fluid through the front chamber than the rear chamber, thereby producing a differential volume flow of fluid through the pump.
It is noted that by use of the separable fastener elements 50, ring members 32 of different configurations may be mounted in the pump to alter the extent of forward movement of the rear diaphragm 16 and hence the displacement achieved by the change in volume of the rear chamber 22 of the pump. Therefore, the differential volume flow of the pump may be changed. It will also be appreciated that the actuating means 64 may be operated selectively to move the diaphragm assembly through one reciprocal motion or continuously if it is desired to produce a continuous differential flow of liquid.
What is claimed is:
1. A differential volume pump comprising:
a cup-shaped front plate having a front wall and an annular outer flange behind said front wall;
a ring member behind said front plate having an outer annular flange with a peripheral configuration complementary to that of said front plate outer flange;
a front flexible diaphragm having an outer periphery disposed between said flanges;
a rear flexible diaphragm having an outer periphery engaging the rear surface of said ring member flange;
the space between said front wall and said front diaphragm providing a first chamber and the space between said diaphragms providing a second chamber, the volume of said first chamber when expanded being greater than that of said second chambere when expanded;
inlet and outlet ports opening into said first chamber;
second inlet and outlet ports opening into said second chamber;
means fastening said outer peripheries of said diaphragms and said flanges together in sealing relationship;
the inner periphery of said ring member extending rearwardly at an angle providing a stop for said rear diaphragm limiting forward movement thereof toward said front wall whereby during movement of the diaphragm toward said front wall the volume of said second chamber is increased; and
means coupled to said diaphragms for moving said diaphragms in unison toward and away from said front wall.
2. A pump as set forth in claim 1 wherein:
said fastening means comprises a plurality of circumferentially spaced bolts extending through said outer peripheries of said diaphragms and said flanges.