JPS6251767A - Device for treating pressurized fluid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to apparatus for handling pressurized fluids. Since the present invention is particularly useful for hot water supply devices, its use will be explained below.

The hot water supply system conventionally includes a storage tank of pressurized construction capable of withstanding very high pressures. This is because whenever the hot water faucet is open, the pressure of the cold water supply pipe is used to pump out the supplied hot water.

For example, if the water supply line pressure is 3-8 atmospheres, the storage tank must be constructed to withstand a maximum pressure of about 12 atmospheres for safety reasons. Such pressurized tank construction requires special materials, seals, safety valves, etc., and these requirements result in very high tank construction and maintenance costs. In some locations, they may not even be allowed to be installed due to safety risks.

It is an object of the present invention to make the container significantly cheaper to manufacture and maintain than pressurized container constructions currently in use by being pumped into a container and delivered in a manner that does not require pressurization of the container. It is an object of the present invention to provide a device for handling pressurized fluid as described above. It will be appreciated that it can also be used in many other applications requiring pressurized fluids, such as heat exchangers, filters, etc.

In accordance with a broad aspect of the invention, a motor is driven by pressurized fluid flowing into the container from an inlet to thereby reduce the pressure of the fluid in the container, and a motor for increasing the pressure of the fluid exiting the container outlet. A pressurized fluid supply device is provided which comprises a container having an inlet connectable to a pressurized fluid supply tube comprising a pump driven by a motor and an outlet connectable to a pressurized fluid outlet tube.

The invention will be described by way of example only below with reference to the accompanying drawings, in which: FIG.

The hot water supply device illustrated in FIG. 1 includes a hot water tank 2 including a hot water heater unit 3, a cold water inlet 4, and a hot water outlet lower for heating water in the hot water tank 2. Hot water is supplied via a control valve 8 to faucets 9 and other consumer devices.

As shown above, such a hot water tank usually has a pressurized structure in order to supply hot water at the outlet lower at substantially the same pressure as the pressure of the cold water supply pipe connected to the cold water inlet 4. It has become. In order to eliminate the need to place the pressurized tank horizontally, a motor pump unit 10 is provided which utilizes the energy of cold water fed into the tank 2 via the inlet 4 to drive a motor within the unit 10. , this motor also drives a pump within the unit 10 to increase the pressure of the cold water delivered from the tank via the outlet lower. Therefore,
The pressurized cold water fed into the unit 10 via the cold water inlet 4 is depressurized at the cold water outlet 5 of the unit 10 before being introduced into the tank 2. Hot water inlet 6 from tank 2
The decompressed hot water sent into the unit 10 via the unit is repressurized in the unit 10 before being discharged from the hot water outlet lower of the unit.

Therefore, the tank 2 may have a non-pressurized structure (the motor pump unit 10 can be called a water pressure recovery device because it restores the pressure at the cold water inlet 4 at the hot water outlet lower part).

FIG. 2 schematically shows the structure of the motor pump unit 10. The unit 10 is divided between the two diaphragms into a central chamber 18 by a pair of deflection members in the form of diaphragms 14, 16 interconnected by a reciprocating member 17/) housings 12 and opposite sides of both diaphragms and 71 housings. It consists of a pair of end chambers 20 & + 20 b between the end walls of. The chamber 18 is such that it also reduces the pressure of the cold water being pumped into the motor chamber or tank inlet 5 using the energy of the pressurized cold water at the inlet 4 to drive the diaphragms 14, 16 in a manner to be described below. It serves as a motor room. Chambers 2o&I 20b connect these chambers 20& from the hot water inlet 6.

The hot water sent into the diaphragm 14°1
It is a pump chamber in that it receives an increase in pressure due to the reciprocating motion of 6 and increases the pressure at the hot water output lower.

Pressurized cold water is first supplied from the cold water inlet hole 4 to the diaphragm 14.
16 plus the diaphragms 14.16 in a first direction (e.g. forward stroke) and then the other of the diaphragms plus the diaphragms 14.16 in the opposite direction (e.g. return stroke). A valve structure indicated at 21 is located within the motor chamber 18 . The valve structure 21 includes an inlet chamber 22 communicating with the pressurized cold water inlet hole 4 and an outlet chamber 24 communicating with the reduced pressure cold water inlet hole 5 .

The inlet chamber 22 has two aligned valve holes 22 in its opposite end walls.
ae 22b is formed, and the outlet chamber 24 is likewise formed in its opposite end walls with two matching valve holes 24&, 24b. The valve stem 26 passes through the inlet chamber 22 and the valve hole 22
&, supports a pair of valve members 26m and 26b that cooperate with 22b. A similar valve stem 28 passes through the outlet chamber 24 and carries a pair of valve members 28a*28b that cooperate with the valve holes 24a, 24b, of this chamber. These two valve stems 26, 28 are fitted with a pair of rings 30 on either side of the valve structure.
It is connected to the reciprocating member 17 through a e 30 b i.

As shown in FIG. 2, a valve member 28 supported by a valve stem 26
ae26m) is placed inside the entrance chamber 22,
A valve member 28 aw 28 b supported by the valve stem 28 is located externally of the outlet member 24 . Furthermore, these valve members are supported by respective valve stems such that one valve member of the valve stems (e.g., valve member 26a of valve stem 26) is closed, and the other valve member (e.g., valve member 26b of valve stem 26) is closed. is open. Valve member 2 of one valve stem (e.g., valve member 2 of valve stem 26)
6b) is open, the valve member of the other valve stem facing the same diaphragm (eg, valve member 28b of the valve stem 28 facing the diaphragm 16) is closed.

The motor chamber 18 further includes a pair of springs 31&, 31tl, each acting on the diaphragm 14.16. Therefore, when the diaphragm 16 moves to the right, the diaphragm 14 also moves to the right (so the spring 31b is relaxed and the spring 31& is compressed.

The housing 10 communicates with the pump chambers 20a, 20b and has two further pairs of IPs 32&#32b and a4m.
, 34b. These valves are one-way valves that allow flow in only one direction. Valve 32&.

32t) is a conduit 36 & where the reduced pressure hot water flows from the inlet 6 to the conduit 36&.

36b into the pump chamber 20 a e 2 Ob, and the valves 34 a r 34 b allow the reduced pressure hot water to flow from the pump chamber through the conduit 38 a e 38 b to the castle pressure hot water outlet lower. enable.

Therefore, it will be understood that when pressurized cold water is introduced into the motor chamber 18 from the inlet 4, the two diaphragms 14, 16 reciprocate together with the reciprocating member 17 connected thereto. The pressure of the fed water is thereby reduced or the motor chamber 18
In the two pump chambers 20a and 2Qb on the opposite side, hot water is sent out from the hot water outlet lower, thereby increasing the pressure of the hot water in the pump chambers.

3 to 6 show the structure of the motor pump unit according to the drawing of FIG. 2. FIG. The same reference numerals are used for corresponding elements to facilitate comparison.

Therefore, the pump motor unit shown in FIGS. 3 to 6 has an inlet 4 for pressurized cold water (OWp) and an inlet 4 for pressurized cold water (OWu
), an inlet 6 for decompressed hot water (HWu), and a lower outlet for pressurized hot water (awp). The housing 10 is cylindrical and has a main cylindrical portion 1.
0m and a pair of curved end portions lQb, 1, and Oa are formed and these are fixed with a large number of bolts lOd.

The diaphragms 14 and 16 are connected to the cylindrical portion 10a of the housing and the end portions 10b as shown in FIG.
It is fixed to the housing by tightening the outer circumferences of the two diaphragms between the two diaphragms. The reciprocating member 17 has a pair of clamping members 17a, 17b and 1 at each end.
70, 17 (L) in the form of a central hollow shaft, between which the two lined members clamp the central region of the two diaphragms 14, 16. The outer clamping member 1
7&, 17d are formed with screw holes 17e and 17f screwed into the ends of the hollow shaft 17, respectively, and a polygonal socket 17gt17h for screwing these into the ends of the hollow shaft 17.

The cylindrical housing part 10& is integrally formed with fittings 4 and 5 forming cold water inlet and outlet holes and further fittings 6 and 7 forming hot water inlet and outlet holes. Also in the housing part 10 & pressurized cold water is first applied from the cold water inlet hole 4 to one of the diaphragms 14, 18 to drive the diaphragm a forward stroke, and then applied to the other of the diaphragms to cause the diaphragm 14, 16 to move forward.
A fixed wall of the valve structure 21 for driving the valve only in the return stroke is integrally formed. As shown in detail in FIG. 6, the wall of the valve structure 21 has an inlet chamber 22 communicating with the inlet hole 4, an outlet chamber 24 communicating with the outlet hole 5, and a potting member connecting the two diaphragms. 17 forms a central chamber 25 between the inlet and outlet chambers that communicate with each other.

The valve stem 26 is formed in the inlet chamber 22 and has an aligned opening 22 &
l 221) through 1. The valve stem 28 supports the valve members 28 a e 28 b that cooperate with these valve ports, and the valve stem 28 is connected to the outlet member 2
A valve member 28& extends through the aligned openings 24a, 24b of 4 and cooperates with these valve ports.

28b is as previously described with respect to FIG. The two valve stems 26 and 28 are connected at their opposite ends by an annular ring 30&t30b to reciprocate the valve stems as a unit so that when valve member 26a is closed (as shown in Figures 2 and 4), the valve member 26b is open and valve member 28b is closed.

The diaphragms 14, 16 define pump chambers 20a, 20b that communicate with the reduced pressure hot water inlet hole 6 and the pressurized hot water outlet hole 7. One-way valve 32&.

32b is arranged on one side of the chamber 20 & 20b and has an inlet hole 6
Non-pressurized hot water is supplied only from the pump chamber 20a.

2Ob, one-way valve 34&
, 34b are these pump chambers 20&.

A one-way valve 241 located on the opposite side of the hot water valve 241
The pressurized hot water is arranged so that it can flow out only from L and 34b to the lower outlet.

An important feature of the motor pump unit shown in FIGS. 3 to 6 is that the pressure applied to each diaphragm 14 and 16 displaces the diaphragm and the reciprocating member 17 by a predetermined distance to open the closed valve opening with a snap action. the valve member 26 a until the opened valve opening is closed with a snap action;
26b and 28a + 28b have their respective valve openings 22a*22b and 24&*24
A yield device was provided connecting these valve members to their respective valves f126.28 to hold the valves closed.

For this purpose, the valve members 28&, 26b and 28a.

28b is in the form of an elastic disk (Fig. 9J4) whose central part is fixed to the respective valve stem 26.2B.

While the outer periphery of the elastic disk defines an annular sealing surface (e.g. 28bs in Figures 7 & 6) to close the valve opening, the inner surface area of the elastic disk defines an elastic connection (e.g. For example, the diameter of the valve stem is significantly smaller than the diameter of the resilient valve head, as shown in FIG. 7a (28bR).

The structure of the valve stems 26, 28 is shown in more detail in FIG. 4, and for operating the valves connected to these stems as described above, the valve head 2 rests on the right end of the valve stem 28.
This is shown in more detail in the valve diagram of FIGS. 7b and 70 in conjunction with FIG. 8b.

Thus, each valve stem 26, 28 has an enlarged head 50, 52 at one end.
It is in the form of a long pin with a nut at the other end. The central part of each valve stem located within the respective chamber 22, 24 includes a sleeve 60, 62, into which the respective valve head is clamped. Thus, with respect to the valve [23b shown in FIG. It can be seen that it is tightened between the

Since the arrangement is as shown in FIG. 4, the two valve heads 26&, 26b are fastened to the valve stem 26 so as to be located in the inlet valve chamber 22, but the two valve heads 26&, 26b are tightened to the valve stem 26, and the two valves m28at28
b is fastened to the valve stem 28 so as to be disposed outside the outlet valve chamber 24.

Figures 7 and 70 schematically show the opening linkage of the valve opening 241) of the valve head 28b. It is understood that this opening movement of the valve head 28b is translated into a closing movement of the valve head 28& with respect to the valve opening 24&, and that these similar movements are
It will be understood that this is also done with respect to the valve openings 22 a F 22 b by 26 b.

Figures 7 and 7 show the resilient valve head 28b in a closed state closing the valve opening 24b. This is the position of the valve head in the state of the motor pump unit shown in FIG. When the motor pump unit is in this state, the valve head 22b is in the open position with respect to the valve opening 22b, so the pressure of the cold water fed through the inlet hole 6 is applied to the diaphragm 16, and the pressure of the cold water is applied to the diaphragm 16. It is also applied to the right side of valve m28b to firmly close the valve head against valve opening 24b, as shown in FIG. The outer annular portion 28bs of the valve head 28b thus firmly biases the valve head 28b against the valve seat in a closed condition.

As discussed in more detail below with respect to Figures 8a-80, the valve stem 28 begins to move to the right, attempting to move the valve head 28b away from the valve opening 241).

This is the situation shown in FIG. 7b. In this intermediate position, the right side of the valve head is still subject to the high pressure on the right side of the pump chamber 18 occupied by the diaphragm 16. During the initial movement of the valve stem 28 to open the valve opening 24b, high pressure from the inlet pipe is now applied to the inner surface of the valve head 2813 (on the left side in Figure 4) in an attempt to force the valve head away from the valve opening. shows a tendency to However, since the surface area on the right side of the valve head is larger than the surface area on the left side of the valve head, and since the valve head is made of an elastic material such as rubber, the outer circumference 28bs of the valve head is in sealing engagement with the valve opening. The inner surface region 28bR of the valve head between the annular sealing surface 28b8 and the attachment part to the valve stem 28 deforms under the opening force applied by the valve stem 28, elongates, and yields. .

The additional force that tends to hold the valve is friction, which is directed tangentially to the valve seat and resists the force that tends to open the valve.

This yielding of the valve head 28b continues until the valve stem 28 has moved a predetermined distance, at which point each of the external forces described above no longer has enough force to maintain the annular seal 28bs against the valve seat. It disappears. At this time, the annular sealing surface 28bs moves with a snap action to open the valve.

The snap opening of the valve opening 241) by the valve head 28b is transmitted to the valve head 28& at the other end of the valve stem via the valve stem 28, thereby closing the valve opening 24& with a snap effect.

As previously mentioned, the two valve stems 26, 28 are fitted with an annular ring 30a and a nut 54 fitted at the end of the valve structure (on the left in FIG. 4) near the enlarged heads 50, 52 of these stems. ．．
They are secured together for movement as a unit by an annular ring 30b fitted on the other end of the valve structure near 56 (on the right side in FIG. 4). Spring 31 & ring 30
a and the clamping member 171) of the diaphragm 14 on one side of the valve structure 21, and the spring 311) is interposed between the ring 30b and the clamping member 17a of the diaphragm 16 on the other side of the valve structure. is interposed between.

Each of the two valve stems 26, 28 includes a bistable member 70, 72 (FIG. 4) in the form of a conical elastic disk, which places the respective valve stem in one of its bistable states. to be maintained. These conical discs are the valve heads 26a as described above.

The opening and closing of 26b and 28at 28b by the nap action is promoted.

Therefore, regarding the state shown in Figure 9, even if the valve stem 26 begins to move to the right due to the engagement of the diaphragm disk 171) with the annular ring 30a, the valve stem will move a predetermined distance and then The conical disk 70 will continue to operate until the elastic force of the valve head 28a and other external forces, as described above, are insufficient to hold the valve opening 26a closed.
The elasticity of the valve head 26& holds the valve head 26a closed with respect to the valve opening 22&. When the elasticity of the valve head and the external force are insufficient, the annular sealing surface of the valve head 28& separates from the wall of the valve opening 22&, allowing snap action movement of the valve stem until it passes the center of the conical disk 70. do. When this occurs, the conical disk exerts its force to complete the movement of the valve stem, snapping the valve head 26b on the other side of the valve stem against the valve opening 22b.

Figures 8 & 80 show the illustrated motor pump unit 10.
The overall operation of is shown in more detail.

Figures 8 & 8 show the motor pump unit 10 at the beginning of the forward stroke of the motor as shown in Figures 2 and 4;
In FIGS. 2 and 4, the diaphragms 14 and 16 are in the leftmost position, and the two valve stems 26, 28 are also in the leftmost position, so that the valve heads 26 m , 28 b are closed;
The valve head 26 b e 23 m is open.

The pressurized cold water pumped through the inlet hole 4 is thus applied to the diaphragm 16, displacing it to the right. The reciprocating member F that connects the diaphragm 16 to the diaphragm 14 further displaces the diaphragm 14 to the right, compressing the spring 31a and loosening the spring 31b. Second
As shown in the figure, the displacement of the diaphragm 16 causes the hot water in the pump chamber 20b to be pushed away under pressure and reach the hot water outlet hole 7 through the one-way valve 34b. At the same time, since the diaphragm 14 is displaced, hot water is drawn into the pump chamber 20a from the inside of the tank 2 via the hot water outlet 6 and the one-way valve 32a, and the cold water in the pump outlet chamber 24 is drawn into the tank 2. (without pressure).

Figure 8b shows the state of the device just before the end of the forward stroke. At the end of the forward stroke, diaphragm 14 has been displaced to the right into a position where it engages ring 30a (Fig. 582) so as to begin movement of the two valve stems 26, 28 to the right. During the initial movement of the two valve stems 26, 28, the elasticity of the valve heads 26at 28b and other external forces described above with respect to FIGS. Area (
For example, 28 bR in FIG.
, 28, so each valve opening 22
a y 24 b can be held closed. However, once the valve stem has traveled a predetermined distance such that the elasticity of the valve head 26a * 28b is insufficient to hold the annular sealing surface in engagement with the valve seat of the valve opening, this annular sealing surface As described above, the valve stems can be moved to the right by moving away from their valve seats in a snap-action motion to open their respective valve openings. This movement of the valve stem is effected by the energy stored in the spring 31a, which forces the valve head 26 b # 28 & against the valve seat as it passes the central part of the bistable conical disk 70, 72. Closed with a snap action. This is number 8. .

As shown in the figure (the state of the motor pump unit).

When the motor pump unit is in this state, the pressurized cold water from the inlet hole 4 is applied to the diaphragm 14, displacing the diaphragm to the left, and displacing the diaphragm 14 to the diaphragm 16 connected to it by the reciprocating member 17. At the same time, the motor pump unit is driven to enter the return stroke. During this return stroke, the hot water in the pump chamber 20& is pressurized and sent to the outlet hole 7 via the one-way valve 34& (Fig. 2), but the non-pressurized hot water from the tank 2 passes through the valve 32b. Then, it is drawn into the pump chamber 20b. moreover,
The pressurized cold water sent through the inlet hole 4 is sent to the outlet hole 5 without being pressurized.
It is sent into tank 2 through.

Near the end of the return stroke, the diaphragm 16 engages the springs 31b of the two valve stems 26, 28 and begins to move the valve stems to the left. At this time, the elasticity of the valve heads 26m and 28b, the energy stored in the spring 31b, and the conical disk 70.
72 bistable and the valve opening 22 b * 24
m is snap action opening and valve opening 22&#24
The snap-action closing of 1) takes place in the same manner as described above at the end of the forward stroke.

The operation of the motor-pump unit 10 involves some volume loss, so that the volume of the motor part 18 is smaller than the volume of the pump parts 20a, 20b, for example by the volume occupied by the reciprocating member 17. Accordingly, as shown in FIG. 1, the tank 2 includes a level detector in the form of a float 90 which connects the cold water supply line creating a bypass for the motor pump unit 10 to the tank via a conduit 92. Controls valve 91 that supplies make-up water.

Although this pressure loss slightly reduces the pressure of the hot water delivered from the motor pump unit 10, this pressure loss is so small that it is not noticeable to consumers in most cases.

It can thus be seen that the hot water tank 2 does not need to be pressurized and therefore does not need a lid. However, in order to prevent the water in the tank from getting dirty, it is preferable to provide a cover 93 on the top of the tank and include an inflatable bag 94 that floats on the water level in the tank. Inflatable bag 94 includes a vent tube 95 that passes through an opening in cover 93 and communicates with the atmosphere. Therefore, the expansion pipe 94 discharges the inside of the tank to the atmosphere, and at the same time, this tank and the cover 93 prevent the water inside the tank from being contaminated. A filter, shown schematically at 96 in FIG. 1, covers the opening in the vent tube 95 to prevent foreign matter from entering the inflation bag 94. Inflatable bag 94 may include a coil spring 97 or other device to prevent its sides from sticking together when the bag is fully deflated. If the sides stick together, there is a risk that expansion of the bag through the vent pipe 95 will be hindered if there is a change in the liquid level in the tank.

Although the invention has been described in terms of one preferred embodiment, it will be understood that many other variations and modifications are possible.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the device of the present invention for storing pressurized hot water in a storage tank and supplying it as needed, and Fig. 2 is an embodiment of the fluid motor pump unit of the present invention. FIG. 3 is a top view of the fluid motor pump unit of FIG. 2, and FIG. 4 is a schematic diagram of the fluid motor pump unit of FIG. J is an enlarged cross-sectional view along the I\-IV line of No. 31fA, Fig. 5 is a cross-sectional view taken along the V-V line of Fig. 3, and Fig. 6 is a cross-sectional view taken along the vt-vt line of Fig. 4. The sectional views, Figures 7a, 7b, and 7C are explanatory diagrams of the operation of each valve in the unit of Figures 1 to 3, and Figures 8 & 8, 8b, and 80 are Figures 3-6. FIG. 3 is a schematic diagram illustrating the operation of the motor pump unit of FIG. In the diagram, 2 is the hot water tank, 4 is the cold water inlet,
5 is a cold water outlet, 6 is a hot water inlet, 7 is a hot water outlet, 10 is a motor pump unit, 17 is a reciprocating member, 14 and 16 are diaphragms, 18 is a motor chamber, 21 is a valve structure, 22 is an inlet chamber, 24 is an outlet chamber, 26 is a first valve stem, 28 is a second valve stem, 26a, 26b are valve heads, and 28&, 28b are valve heads. Patent Applicant Kur Metals Limited VIG 7a Procedural Amendment 2 Jealous Dot) Before 40 Cats 2 Cotton Eulwei Kclct Miu Stalk Arashi 3, Person Who Makes Amendment Relationship with Case No. 4'4L41λ Ren-Yunsu Company transfer name Quarmetal 2 reply 9mi fund 4, agent! , Ne' it) Kashi Karikyo or Jojo (n 11 zei Shikyuputra 1 kind mouth Renzu mourning study 1. Taseme 2 1 shift)

Claims (1)

[Claims] 1. A motor driven by pressurized fluid flowing into the container from an inlet, thereby reducing the pressure of the fluid in the container, and a motor driven by the motor to increase the pressure of the fluid exiting the container. A pressurized fluid supply device comprising a container having an inlet connectable to a pressurized fluid supply pipe comprising a driven pump and an outlet connectable to a pressurized fluid outlet pipe. 2. The motor drives a reciprocating member that reciprocates forward and backward strokes, and the reciprocating member in turn drives the pump during the forward and backward strokes, and further switches fluid flow through the motor and pump at the end of each stroke. Apparatus according to scope 1. 3. The motor according to claim 2, wherein the motor includes two expansion and compression chambers located on both sides of the reciprocating member, and the pump includes two expansion and compression chambers located on both sides of the reciprocating member. Device. 4. The motor and the pump have a common housing, and a pair of displacement members disposed on both sides of the reciprocating member divides the inside of the housing, and a motor chamber and a pair of displacement members on both sides of the motor chamber are provided between the displacement members. a pair of displacement members forming a pump chamber; a first inlet hole communicating with the motor chamber for delivering a first pressurized fluid for driving the reciprocating member;
a first communicating with the motor chamber for delivering the fluid after depressurization;
an outlet hole, a second inlet hole that communicates with the two pump chambers for delivering a second reduced pressure fluid, and a second outlet hole that communicates with the two pump chambers for delivering the second fluid after reducing the pressure;
The reciprocating member is actuated by first applying pressurized fluid from the inlet hole to one of the displacement members to drive it in a first direction and then to the other displacement member to drive it in the opposite direction. a reciprocating valve structure, the valve structure having an inlet chamber including an end wall having a pair of first valve openings therethrough in communication with the inlet aperture, and a second pair of valves in communication with the outlet aperture. an outlet chamber including an end wall with an opening; a first valve stem disposed in the inlet chamber supporting a first pair of valve members for opening and closing the valve opening in the inlet chamber; a second valve stem disposed in the outlet chamber supporting a second pair of valve members to open and close the opening; the other valve member being closed and the second pair of valve members facing the same displacement member as the first pair of open valve members being supported by their respective valve stems so as to be closed; 3. A device according to claim 2, wherein the device is connected to a reciprocating member reciprocated by a reciprocating member. 5. The pressure applied to each displacement member displaces the valve stem by a predetermined distance determined by the yield strength of the yielding device, and opens the closed valve opening with a snap action, and the opened valve opening is opened with a snap action. Claim 4 including a yielding device connecting the sealing surface of the valve member to the respective valve stem such that the closed valve opening remains closed by the sealing surface until closed. Device. 6. Claims including a first pair of one-way valves between the pump chamber and the second fluid inlet, and a second pair of one-way valves between the pump chamber and the second fluid outlet. Apparatus according to paragraph 5. 7. Claims in which the valve structure further comprises a bistable member that acts on the valve stem to maintain the valve stem in one or the other of its positions to enhance the snap-action opening and closing of the valve opening. Apparatus according to any of clauses 5 or 6. 8. Any one of claims 5 to 7, wherein the valve member has an annular sealing surface, and the yielding device comprises a resilient connection between the annular sealing surface and its respective valve stem. Equipment described in Section. 9. The valve member is an elastic disk whose central part is fixed to the valve stem, the outer circumference of the elastic disk defines the annular sealing surface, and the inner surface area of the elastic disk defines an elastic connection to the valve stem. 9. A device according to claim 8, adapted to do so. 10. The device according to any one of claims 4 to 9, wherein the pair of displacement members are diaphragms connected by the reciprocating member.