US20070201985A1

US20070201985A1 - Diaphragm pump of constant pressure type

Info

Publication number: US20070201985A1
Application number: US11/395,313
Authority: US
Inventors: Chao Hsu
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-02-27
Filing date: 2006-04-03
Publication date: 2007-08-30

Abstract

The present invention provides a diaphragm pump of constant pressure type, mainly wherein a passage tube links between said pressure discharge port and said inlet port of said pump cover body; Thereby, the extra water pressure coming from said compressed chamber can be orderly discharged through said pressure discharge port, next guided through said passage tube to reach said inlet port, then directly flowed into said low pressure chamber; Therefore, a close water circulation loop of discharge pressure is built by means of connecting said compressed chamber, said pressure discharge port, said passage tube, said inlet port and said low pressure chamber; Thus, the present invention not only provides the function of keeping constant pressure, but also completely recycles the drained water by extra water pressure without any waste in water resource; Moreover, the present invention not only has the energy-saving effect in power consumption, but also has the environment-protecting effect in reducing operation noise; Thus, it is really an innovative invention with multiple practical effect.

Description

FIELD OF THE PRESENT INVENTION

The present invention relates to the pressurized diaphragm pump, which being exclusively used in the reverse osmosis purification apparatus, particularly for the capability of discharging the exceeding water pressure in the compressed chamber of the pressurized diaphragm pump out of its pump cover body, then directing it into the low pressure chamber by way of the inlet port; so that the water pressure of the outlet port in said pump cover body can be kept in a expected constant value.

BACKGROUND OF THE INVENTION

Currently, the pressurized diaphragm pump types used in the reverse osmosis purification apparatus, such as U.S. Pat. Nos. 4,396,357, 4,610,605, 5,476,367, 5,571,000, 5,615,597, 5,626,464, 5,649,812, 5,706,715, 5,791,882, 5,816,133, 6,048,183, 6,089,838, 6,299,414, 6,604,909, 6,840,745 and 6,892,624 are all disclosed; The best seller of the pressurized diaphragm pump exclusively used in the conventional reverse osmosis purification apparatus is shown in the FIG. 1 through FIG. 3, comprising: a motor 10; an upper lid chassis 11, which being on the top end of the output shaft (not shown in the figure) of said motor 10, has some screw bores 12 set up on its circumference; some wobble plates 13, which being hinged in said upper lid chassis 11, are driven by the output shaft of said motor 10 and being transferred into axially reciprocating motion; a diaphragm valve frame 20, which covering on said upper lid chassis 11, has a high pressure valve 21 embedded in the center of its top with some low pressure valves 22 being embedded at the bottom side of the circumference of said high pressure valve 21; and a pump cover body 30; All the components aforesaid are firmly screwed together as a integral body by the bolts 2 running through said screw bores 12 on said upper lid chassis 11 and corresponding perforated bores 36 on said pump cover body 30 (as shown in the FIG. 2).
Wherein said pump cover body 30, an inlet port 31 and an outlet port 32 are contrived on both corresponding ends of its outer rim; a ladder groove 37 is circled at the bottom of its inner side such that can stay closely with the periphery of said diaphragm valve frame 20; an annular groove 38 facing towards said ladder groove 37 is raised in the center of its inner side with an outlet orifice 35 perforated to conduct with said outlet port 32; Wherein, the top end of said annular groove 38 presses closely with the periphery of said high pressure valve 21 on said diaphragm valve frame 20, so that a compressed chamber 34 is formed between the inner side of said annular groove 38 and said diaphragm valve frame 20 as well as some low pressure chamber 33 being formed among the outer side of said annular groove 38 and the inner side of said pump cover body 30 (as shown in the FIG. 1 and the FIG. 2).
Refer to the FIG. 1 through the FIG. 3, the unfiltered feed water W, which entering said inlet port 31 of said pump cover body 30, first reaches said low pressure chamber 33 for being increased its pressure up to 60 psi˜120 psi normal rated pressure; In said low pressure chamber 33, the reciprocating axially motion of said wobble plates 13 driven by said motor 10 will force all said low pressure valves 22 movement orderly for suction and compression of said feed water W so as to increase to water pressure; The pressurized feed water W flows into said compressed chamber 34 through high pressure valve 21, next passes said outlet orifice 35 of said annular groove 38, then directly drains out of the pressurized diaphragm pump from said outlet port 32 of said pump cover body 30; Said pressurized feed water W with water pressure, which conforms to the normal rated water pressure of the reverse osmosis semi-permeable membrane filter cartridge or module (not shown in the figure, hereinafter called RO membrane), is output and supplied to the reverse osmosis purification apparatus for filtration and purification.
Currently, all the various RO membrane in the market have mark indicating the normal rated water pressure and the service life in different specification basically depending on the quantity of water being filtrated; For example, the RO membrane with less filtrating quantity of water might have mark indicating that the quantity of the product filtrated drinking water per day under normal rated water pressure of 60 psi is 10 gallons, and the total filtrating quantity of water in durable service life is 1500 gallons; Hence, the output water pressure of the pressurized diaphragm pump to be used in match with such RO membrane is better not to exceed 60 psi, otherwise it will quickly shorten the service life of said RO membrane. For some non-residential places, which demand much more quantity of product water, the RO membrane with ample specification will be adopted for having relative high normal rated water pressure up to 100 psi˜120 psi and the quantity of the product filtrated drinking water per day is up to 160 gallons; In this case, the output water pressure of the pressurized diaphragm pump to be used in match with such RO membrane is better to reach 120 psi. Therefore, all the domestic or overseas manufacturers of the pressurized diaphragm pump will specify their product with normal rated water pressure of 120 psi to meet different specifications of the RO membrane.
However, the way described above has serious drawback in discrepancy of the pressurized diaphragm pump and the RO membrane, namely the normal rated water pressure of the RO membrane is 60 psi or 70 psi and that of the pressurized diaphragm pump is 120 psi; Under such circumstance, the fibrous filter material in the RO membrane will be torn so that the interstices in between become bigger gradually due to constant high pressure stress; Thereby, not only the function in filtering the turbidity of impurities is diminished, but also the durable service life is shortened; Thus, the consumer becomes a victim owing to the frequency of replacing new RO membrane is increased in consequence of these adverse effects aforesaid. Moreover, as shown in the FIG. 3, the RO membrane will be gradually fouled by the filtered impurities during filtering service time; Hence the pressurized water coming from the compressed chamber 34 in the pump cover body 30 of the pressurized diaphragm pump can not completely flow into said pump cover body 30 and resulting in backwater pressure against the diaphragm valve frame 20; Thereby, the leakage will happens between said pump cover body 30 and said diaphragm valve frame 20 due to constant backwater pressure in long-term; Again, the consumer becomes a victim out of luck owing to the timing of replacing said entire pressurized diaphragm pump is earlier than the marked expiry time in consequence of the leakage aforesaid.
The drawbacks aforesaid include all the conventional pressurized diaphragm pumps of USA patents disclosed; Since 1985 the pressurized diaphragm pump was invented, there was not any contrivance to remedy the drawbacks aforesaid for a long time until recently three years when new contrivance of the pressurized diaphragm pump with design in regulating the exceeding high water pressure in the compressed chamber 44 being introduced into market; the structure is as shown in the FIG. 4 through the FIG. 7, A pressure discharge cavity 47 is formed in the center of the compressed chamber 44, which being in the inner side of the pump cover body 40, and a pressure adjusting base 50 is built in the top center of the outer side of said pump cover body 40, wherein: In said pressure discharge cavity 47, a pressure discharge orifice 48 is perforated at the center at its bottom side, and a pressure discharge channel 49 is perforated at it lateral side such that the end conducts to the low pressure chamber 43; For said pressure adjusting base 50, pressure adjusting screw 51 is inset in its center such that the end internally with a compressed spring 52 and a baffle rod 53 protruding into said pressure discharge cavity 47; Said baffle rod 53 stays closely against said pressure discharge orifice 48 of said pressure discharge cavity 47 by the spring force of said compressed spring 52. Refer to the FIG. 8 and FIG. 9, when the feed water W flows into said low pressure chamber 43 through said inlet port 41, its pressure will be increased by the action of the wobble plate 13; Then, said feed water W flows into said compressed chamber 44 through said low pressure valve 22 and high pressure valve 21; Finally, said feed water W flows for the RO membrane with normal rated pressure through said outlet orifice 46 and outlet port 42; Under normal rated pressure, said baffle rod 53 will stay closely and block said pressure discharge orifice 48 of said pressure discharge cavity 47 by means of the spring force of said compressed spring 52 acting on said baffle rod 53; Therefore, all the pressurized feed water W from said compressed chamber 44 will output out of said pump cover body 40 through outlet orifice 46 and outlet port 42 (as shown in the FIG. 8); When the water pressure in said compressed chamber 44 exceeds the normal rated pressure, the water pressure will push said baffle rod 53 off said pressure discharge orifice 48 to allow the extra water pressure feedback into said low pressure chamber 43 through said pressure discharge orifice 48 and pressure discharge cavity 47 as well as pressure discharge channel 49 (as shown in the FIG. 9) so as to regulate the water pressure in said compressed chamber 44. However, the conventional pressurized diaphragm pump of internal pressure regulating type actually does not discharge the internal extra water pressure out of itself; It only constantly circulates the extra water pressure among said compressed chamber 44 and said low pressure chamber 43; So, the problem of the holding and exceeding of the water pressure in said compressed chamber 44 will happen after said pressurized diaphragm pump running for a period of time.
Accordingly, after the inventor of the present invention finds out the drawback aforesaid, he renders a remedy contrivance and patent application to the IPO of Taiwan at Jan. 14 of 2003 as well as being allowanced and granted the patent number 225942 (publication number: 595656) in file. Its structure is as shown in the FIG. 10 through 14: In the pressure adjusting groove 68, which being indented at the outer top of the pump cover body 60 with facing inwards of the annular groove 65, a pressure discharge orifice 67 is perforated at its bottom side with facing towards said annular groove 65; For said pressure adjusting groove 68, an adjusting screw 200 is inset in said pressure adjusting groove 68 such that the end internally with a compressed spring 201 and a baffle lump 202; Wherein, said baffle lump 202 stays closely against said pressure discharge orifice 67 by the spring force of said compressed spring 201.
Refer to the FIG. 11 and the FIG. 13, when the water pressure of the pressurized feed water W from said compressed chamber 64 is under normal rated pressure, said baffle lump 202 can not be pushed off and will still block said pressure discharge orifice 67; Therefore, all the pressurized feed water W from said compressed chamber 64 will output out of said pump cover body 60 through outlet orifice 66 and outlet port 62 (as shown in the FIG. 11); When the water pressure in said compressed chamber 64 exceeds the normal rated pressure, the water pressure will push said baffle lump 202 off said pressure discharge orifice 67 to allow the extra water pressure discharge out of said pump cover body 60 through said pressure discharge orifice 67 and pressure discharge port 69 (as shown in the FIG. 13); When the water pressure in said compressed chamber 64 descends back below the normal rated pressure, said baffle lump 202 will bounce back by the spring force of said compressed spring 201 to return closely and block said pressure discharge orifice 67 to inhibit the extra water pressure discharge out so as to keep the water pressure in said compressed chamber 64 in the range of normal rated water pressure (as shown in the FIG. 11); Therefore, the aforesaid pressurized diaphragm pump contrived by the identical inventor of the present invention is a real effective remedy in regulating the exceeding water pressure as well as discharging the extra water pressure out. Moreover, in order to prevent the water drained out of said pressure discharge port 69 from spilling everywhere, a water pipe P sleeves on said pressure discharge port 69 so as to guide the drained water into the water container (as shown in the FIG. 14).
Because the aforesaid pressurized diaphragm pump contrived by the identical inventor of the present invention can completely meet the normal rated water pressure in all kinds of the RO membrane as well as free the consumer from frequently replacing said RO membrane and said pressurized diaphragm pump, it received popularly good feedback comments after being introduced in the market. But, said applicant is not satisfied with this achievement, he keeps constantly contemplation, research and study as well as attempts anxiously to breakthrough in order to reach better condition; Thereby, he finds out some issues to be improved as below:
1. Although the extra water, which being drained out of the pump cover body 60 from the pressure discharge port 69, can be guided into a general water container for collecting to reuse, it causes the user another boring matter in need of preparing water container or burdensome collecting water; For convenience, most of the consumers will select to dump it out and resulting in wasting water resource.
2. The water running noise accompanying with the draining of the extra water out of the pump cover body 60 from the pressure discharge port 69 will interfere with the internal calmness and peace of the residential environment.

SUMMARY OF THE INVENTION

A main object of the present invention is to provide a diaphragm pump of constant pressure type, mainly wherein a passage tube links between said pressure discharge port and said inlet port of said pump cover body; Thereby, the extra water pressure coming from said compressed chamber can be orderly discharged through said pressure discharge port, next guided through said passage tube to reach said inlet port, then directly flowed into said low pressure chamber; Therefore, a close water circulation loop of discharge pressure is built by means of connecting said compressed chamber, said pressure discharge port, said passage tube, said inlet port and said low pressure chamber; Thus, it not only saves the drain water by the extra water pressure from directing into the other prepared container, but also solves the inconvenience and wasting in reluctantly recycling from the side effect of such inconvenience.
Another object of the present invention is to provide a diaphragm pump of constant pressure type, wherein the extra water pressure will directly flow into said inlet port to converge with the input water pressure; Thereby, the total input water pressure of the pressurized diaphragm pump is increased so as to save the motive power of the motor indirectly as well as achieving the energy-saving effect of saving power consumption.
The other object of the present invention is to provide a diaphragm pump of constant pressure type, wherein a circulating buffer annular groove is indented around said pressure discharge orifice at the outer circumference of the intersection of said pressure adjusting groove and said pressure discharge orifice; Thereby, the extra water pressure being forced to flow into said circulating buffer annular groove before running into said pressure discharge port; Thus, it has the effect in reducing the operation noise of the pressurized diaphragm pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the perspective exploded view of the conventional pressurized diaphragm pump.
FIG. 2 is the first illustrative view showing the cross-section of the pump cover body in the conventional pressurized diaphragm pump.
FIG. 3 is the second illustrative view showing the cross-section of the pump cover body in the conventional pressurized diaphragm pump.
FIG. 4 is the first illustrative view showing the perspective of the pump cover body in the conventional pressurized diaphragm pump of internal pressure regulating type.
FIG. 5 is the second illustrative view showing the perspective of the pump cover body in the conventional pressurized diaphragm pump of internal pressure regulating type.
FIG. 6 is a sectional view taken along the direction indicated by a line 6-6 as shown in FIG. 5.
FIG. 7 is a sectional view taken along the direction indicated by a line 7-7 as shown in FIG. 5.
FIG. 8 is the first illustrative view showing the operation of the pump cover body in the conventional pressurized diaphragm pump of internal pressure regulating type.
FIG. 9 is the second illustrative view showing the operation of the pump cover body in the conventional pressurized diaphragm pump of internal pressure regulating type.
FIG. 10 is the illustrative view showing the perspective of the pump cover body in the conventional pressurized diaphragm pump of external pressure regulating type.
FIG. 11 is a sectional view taken along the direction indicated by a line 11-11 as shown in FIG. 10.
FIG. 12 is a sectional view taken along the direction indicated by a line 12-12 as shown in FIG. 10.
FIG. 13 is the illustrative view showing the operation of the pump cover body in the conventional pressurized diaphragm pump of external pressure regulating type.
FIG. 14 is the illustrative view showing the cross-section of the pump cover body in the conventional pressurized diaphragm pump of external pressure regulating type.
FIG. 15 is the perspective exploded view of the present invention.
FIG. 16 is the first illustrative view showing the perspective of the pump cover body of the present invention.
FIG. 17 is the second illustrative view showing the perspective of the pump cover body of the present invention.
FIG. 18 is a sectional view taken along the direction indicated by a line 18-18 as shown in FIG. 16.
FIG. 19 is a sectional view taken along the direction indicated by a line 19-19 as shown in FIG. 16.
FIG. 20 is the first illustrative view showing the operation of the present invention.
FIG. 21 is the second illustrative view showing the operation of the present invention.
FIG. 22 is the first illustrative view showing the operation of the backflow buffer annular groove contrived in the pressure adjusting groove of the present invention.
FIG. 23 is the second illustrative view showing the operation of the backflow buffer annular groove contrived in the pressure adjusting groove of the present invention.
FIG. 24 is the elevation view of the pump cover body in another embodiment of the present invention.
FIG. 25 is a sectional view taken along the direction indicated by a line 25-25 as shown in FIG. 24.
FIG. 26 is a sectional view taken along the direction indicated by a line 25-25 as shown in FIG. 24 with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Refer to the FIG. 15 through the FIG. 21, the first embodiment of the present invention comprises: a motor 10; an upper lid chassis 11, which being on the top end of the output shaft (not shown in the figure) of said motor 10, has some screw bores 12 set up on its circumference; some wobble plate 13, which being hinged in said upper lid chassis 11, are driven by the output shaft of said motor 10 and being transferred into axially reciprocating motion; a diaphragm valve frame 20, which covering on said upper lid chassis 11, has a high pressure valve 23 embedded in the center of its top with some low pressure valves 22 being embedded at the bottom side of the circumference of said high pressure valve 23; and a pump cover body 70; All the components aforesaid are firmly screwed together as a integral body by the bolts 2 running through said screw bores 12 on said upper lid chassis 11 and corresponding perforated bores 701 on said pump cover body 70 (as shown in the FIG. 15).
Wherein said pump cover body 70, an inlet port 71 and an outlet port 72 are contrived on both corresponding ends of its outer rim; a ladder groove 702 is circled at the bottom of its inner side such that can stay closely with the periphery of said diaphragm valve frame 20; an annular groove 75 facing towards said ladder groove 702 is raised in the center of its inner side with an outlet orifice 76 perforated to conduct with said outlet port 72; Wherein, the top end of said annular groove 75 presses closely with the periphery of said high pressure valve 23 on said diaphragm valve frame 20, so that a compressed chamber 74 is formed between the inner side of said annular groove 75 and said diaphragm valve frame 20 as well as some low pressure chamber 73 being formed among the outer side of said annular groove 75 and the inner side of said pump cover body 70 (as shown in the FIG. 17 and FIG. 18). In the pressure adjusting groove 78, which being indented at the outer top of the pump cover body 70 with facing inwards of the annular groove 75, a pressure discharge orifice 77 is perforated at its bottom side with facing towards said annular groove 75; For said pressure adjusting groove 78, an adjusting screw 80 is inset in said pressure adjusting groove 78 such that the end internally with a compressed spring 81 and a baffle lump 82; Wherein, said baffle lump 82 stays closely against said pressure discharge orifice 77 by the spring force of said compressed spring 81 (as shown in the FIG. 18). Wherein, a passage tube 90 links between said pressure discharge port 79 and said inlet port 71 of said pump cover body 70 such that said passage tube 90 and said inlet port 71 being screwed to a three-way manifold T (as shown in the FIGS. 16 and 19); By means of connecting said compressed chamber 74, said pressure discharge port 79, said passage tube 90, said inlet port 71 and said low pressure chamber 73, a close water circulation loop of discharge pressure can be built.
Refer to the FIGS. 20 and 21, when the water pressure of the pressurized feed water W from said compressed chamber 74 is under normal rated pressure, said baffle lump 82 can not be pushed off and will still block said pressure discharge orifice 77; Therefore, all the pressurized feed water W from said compressed chamber 74 will output out of said pump cover body 70 through outlet orifice 76 and outlet port 72 (as shown in the FIG. 20); When the water pressure in said compressed chamber 74 exceeds the normal rated pressure, the water pressure will push said baffle lump 82 off said pressure discharge orifice 77 to allow the extra water pressure discharge out of said pump cover body 70 through said pressure discharge orifice 77 and pressure discharge port 79; Then, the extra water pressure will directly flow into said low pressure chamber 73 in said pump cover body 70 by way of said three-way manifold T, which connecting both of said passage tube 90 and said inlet port 71 (as shown in the FIGS. 21 and 17); Simultaneously, the input water pressure coming from the other inlet orifice of said three-way manifold T will joins with said extra water pressure coming from said passage tube 90 and converges together to flow into said low pressure chamber 73 in said pump cover body 70. In other words, if the input water pressure of the pump cover body 70 is 50 psi, the normal rated water pressure of the product water W is 80 psi, and the water pressure in said compressed chamber 74 reaches 90 psi, the extra water pressure is 10 psi (90 psi −80 psi =10 psi); Then, said 10 psi extra water pressure will run through said passage tube 90 and converges with said 50 psi input water pressure becoming 60 psi (50 psi +10 psi =60 psi); Namely, the power of said motor 10 needs to supply water pressure in 60 psi is only equivalent to supply water pressure in 50 psi, means for saving 10 psi converting into less relative power consumption; As long as any extra water pressure being discharged and circulated to said inlet port 71, the energy-saving is effected; For long-term accumulation of said saving energy, it becomes a considerable figure; Moreover, not only the service life of said motor 10 is prolonged due to running in less power consumption, but also the durable service life of said RO membrane is extended owing to the output water pressure from said pump cover body 70 being always kept in constant; All these triple advantages are the desirable merits of the present invention to be praised.
When the water pressure in said compressed chamber 74 descends back below the normal rated pressure, said baffle lump 82 will bounce back by the spring force of said compressed spring 81 to return closely and block said pressure discharge orifice 77 to inhibit the extra water pressure discharge out so as to keep the water pressure in said compressed chamber 74 in the range of normal rated water pressure (as shown in the FIG. 20).
Refer to the FIG. 22 and the FIG. 23, a circulating buffer annular groove 781 is indented around said pressure discharge orifice 77 at the outer circumference of the intersection of said pressure adjusting groove 78 and said pressure discharge orifice 77; Wherein, the lateral side of said circulating buffer annular groove 781 and said pressure discharge port 79 is conducted each other, so that the extra water pressure coming from said pressure discharge orifice 77 being forced to flow into said circulating buffer annular groove 781 before running into said pressure discharge port 79 (as shown in the FIG. 23); Thus, it has the effect in reducing the noise of running water.
The second embodiment of the present invention is shown in the FIG. 24 through the FIG. 26. Wherein said passage tube 100 connecting between said pressure discharge port 79 and said inlet port 71 of said pump cover body 70 is an unitary integral body being molded together with said pump cover body 70.
In conclusion, the present invention really provides the function of keeping constant pressure to conform with the normal rated water pressure of the RO membrane; Besides, the power consumption of the present invention is less than that of all the conventional pressurized diaphragm pumps; Moreover, the present invention not only has the energy-saving effect in power consumption, but also has the environment-protecting effect in reducing operation noise; Thus, it is really an innovative invention to conform to the industrial application.

Claims

1. A diaphragm pump of constant pressure type, which comprises:

a motor;

an upper lid chassis, which being on the top end of the output shaft of said motor and has some screw bores set up on its circumference;

three wobble plates, which being hinged in said upper lid chassis and are driven by the output shaft of said motor and being transferred into axially reciprocating motion;

a diaphragm valve frame, which covering on said upper lid chassis and has a high pressure valve embedded in the center of its top with some low pressure valves being embedded at the bottom side of the circumference of said high pressure valve; and

the pump cover body, having an inlet port and an outlet port are contrived on both corresponding ends of its outer rim; a ladder groove is circled at the bottom of its inner side; an annular groove facing towards said ladder groove is raised in the center of its inner side with an outlet orifice perforated to conduct with said outlet port; Wherein, the top end of said annular groove presses closely with the periphery of said high pressure valve on said diaphragm valve frame, so that a compressed chamber is formed between the inner side of said annular groove and said diaphragm valve frame as well as some low pressure chamber being formed among the outer side of said annular groove and the inner side of said pump cover body; In the pressure adjusting groove, which being indented at the outer top of the pump cover body with facing inwards of the annular groove, a pressure discharge orifice is perforated at its bottom side with facing towards said annular groove; An adjusting screw is inset in said pressure adjusting groove such that the end internally with a compressed spring and a baffle lump; Wherein, a passage tube links between said pressure discharge port and said inlet port of said pump cover body such that said compressed chamber, said pressure discharge port, said passage tube, said inlet port and said low pressure chamber building a close water circulation loop of discharge pressure.

2. A diaphragm pump of constant pressure type as recited in the claim 1, wherein said passage tube is a bendable tube with flexibility.

3. A diaphragm pump of constant pressure type as recited in the claim 1, wherein a circulating buffer annular groove is indented around said pressure discharge orifice at the outer circumference of the intersection of said pressure adjusting groove and said pressure discharge orifice; And, the lateral side of said circulating buffer annular groove and said pressure discharge port is conducted each other.

4. A diaphragm pump of constant pressure type as recited in the claim 1, wherein said passage tube is an unitary integral body being molded together with said pump cover body.

5. A diaphragm pump of constant pressure type as recited in the claim 2, wherein said passage tube and said inlet port being screwed to by a three-way manifold T.