Flow resistance setting nozzle

ABSTRACT

A flow resistance setting nozzle capable of easily setting a target flow rate is provided. A metallic block has a through-bore through which a flow path forming metallic pipe is inserted. A pressing member in the form of a rectangular cross-section bar abuts the pipe at a first abut portion. An anvil having a distal end with an arcuate surface is mounted to the metallic block such that the distal end abuts the pipe at a second abut portion that is opposite to the first abut portion. A coarse adjustment screw presses a center portion of the pressing member against the pipe to squeeze the pipe between the pressing member and the anvil to form an orifice in the pipe. Two fine adjustment screws impart a force to the pressing member to further squeeze the pipe until the target flow rate is set.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the flow resistance setting nozzle according to this invention is illustrated in FIGS. 1A-5, in which the like reference numerals and characters designate the like elements. In the drawings, is a metallic block which is shown in the illustrated example as comprising two block pieces A and B coupled together by screws . The metallic block has a pipe receiving through-bore formed therethrough.

indicates a pipe inserted in the pipe receiving through-bore , and indicates seal members (O-rings) for forming seals between the outer peripheral surface of the pipe and the inner wall BB of the pipe receiving through-bore .

The pipe receiving through-bore extends through the metallic block perpendicularly to the mating plane D of the two divided block pieces A and B, and the pipe is inserted in the bore on the central axis X thereof.

The pipe receiving through-bore comprises an inlet bore section A having an inlet BA, an outlet bore section B having an outlet BB, a central bore section C, a first intermediate bore section D extending between the inlet bore section A and the central bore section C, and a second intermediate bore section E extending between the outlet bore section B and the central bore section C.

The first and second intermediate bore sections D and E are reduced in their inner diameters to the extent that they are only slightly larger than the outer diameter of the pipe .

The inlet bore section A and the outlet bore section B have tapered portions AB and BB, respectively progressively increasing in diameter as they extend from the first and second intermediate bore section D, E and inner threaded portions AC and BC, respectively extending between the tapered portions AB and BB and the corresponding inlet AA and outlet BA.

In the inlet bore section A and the outlet bore section B, seal members (O-rings) are fitted around the pipe and then attachments having outer threads engageable with the inner threaded portions AC and BC are fitted around the pipe outside of the seal members . Then, the attachments are threaded into the inlet bore section A and the outlet bore section B to clamp the seal members (O-rings) between the outer periphery of the pipe and the inner walls of the tapered portions AB and BB of the pipe receiving through-bore to thereby form seals between the pipe and the inner wall of the through-bore . In this way, the pipe is completely sealed off from the central bore section C which is in communication with the outside air, whereby the pipe defines a flow path so that all of the gas supplied from the inlet AA of the pipe receiving through-bore is passed through the pipe and discharged from the outlet BA.

The metallic block is further formed therethrough with a pressing member receiving bore extending in a direction (Z-axis direction) orthogonal to the pipe receiving through-bore (X-axis direction). The central Z axis of the pressing member receiving bore is offset in the Y-axis direction from the central X axis of the pipe receiving through-bore as shown in FIG. 1A, but the two bores are in communication with each other at the point of intersection of the two as seen in FIGS. 1A-1B, and A-C.

A pressing member is inserted in the pressing member receiving bore . As shown in FIGS. 4A and 4B, the pressing member is formed of a rectangular cross-section metallic bar and has transverse through-apertures B and C formed therethrough at symmetrically distant positions which locate with substantially equal distances in longitudinally opposite directions of the pressing member from the center position thereof.

In addition, the metallic block is formed with a threaded hole through which a coarse adjustment screw is to be threaded, and two screwdriving apertures through which two fine adjustment screws are inserted to be screw-driven at symmetrically distant positions which locate with substantially equal distances from the threaded hole , both the threaded hole and the screwdriving apertures extending in parallel to each other in Y-axis direction to orthogonally intersect to and communicate with the pressing member receiving bore .

As shown in FIG. 3A, the pressing member is inserted in the pressing member receiving bore in a manner such that it rests on the upper outer peripheral surface of the pipe transversely thereof, that the central axis Y of the threaded hole in which the coarse adjustment screw is threaded intersects orthogonally to the pressing member at the center position A thereof and the longitudinal axis X of the pipe (see FIG. ).

The distances from the two screw driving apertures formed in the metallic block piece B with the threaded hole located therebetween to the threaded hole are made equal to the distances from the corresponding two through-apertures B and C formed in the pressing member to the central position A of the pressing member .

The through-apertures B and C formed in the pressing member inserted in the pressing member receiving bore are located in opposition to the corresponding fine-tuning screw driving apertures .

With this arrangement, the centers of the distal end of the coarse adjustment screw threaded in the threaded hole is brought into pressure contact with the pressing member at its center position A to urge the latter against the pipe at a first abut portion A thereof (This situation is shown in FIG. 3A.)

In addition, threaded holes into which corresponding fine adjustment screws are to be threaded are formed in the metallic block in opposition to and coaxially with the corresponding two screwdriving apertures with the pressing member receiving bore located therebetween.

The fine adjustment screws each includes a head portion A and a threaded shank portion B. The diameter of the through-apertures B and C formed in the pressing member is oversized relative to the diameter of the threaded shank portions B of the fine adjustment screws , while the head portion of the screw is oversized relative to the diameter of the through-apertures B and C, so that the threaded shank portion of the screws can be loosely passed through the associated screwdriving apertures and the through-apertures B, C in the pressing member and cross the pressing member receiving bore while the head portion cannot be passed, so that the threaded shank portions B is threaded into the opposed threaded holes (see FIGS. 3A-3C) whereby the head portions A of the fine adjustment screws are brought into pressure engagement with the pressing member to urge the latter against the pipe to thereby accomplish the fine adjustment operation.

The coarse adjustment screw and the head portions A of the fine adjustment screws are recessed in the corresponding threaded hole and the corresponding two screwdriving apertures , respectively as shown in FIGS. 3A-3C.

The metallic block is further formed with an anvil mounting aperture on a side of the pipe opposite to the threaded hole so as to align with and oppose to the coarse adjustment screw .

An anvil is mounted in the anvil mounting aperture and comprises an upstanding portion A and a base portion B which is secured to the metallic block by means of screws C such that the upstanding portion A extends through the aperture into the pipe receiving through-bore to abut against the pipe at a second abut portion B thereof, which is opposite to the first abut portion and opposes to the coarse adjustment screw. The upstanding portion A has an arcuate top surface AA. This top surface AA is curved in the X-axis direction of the pipe with a top ridge R as shown in FIGS. 1A, B and oriented in a direction orthogonal to the cylindrical surface of the pipe such that as the pipe is pressed against the anvil by the pressing member to abut at the first abut portion A of the pipe, an orifice decreasing in cross-sectional area progressively in the X axial direction of the pipe up to the minimum cross-sectional area, the distance of which is shown as MS (see FIGS. 1B and 3B) and then progressively increasing in cross-sectional area is formed.

FIGS. 1A and 3A show the condition prior to the commencement of the coarse adjustment operation wherein pressing or squeezing force is ready to be applied to the pipe . In this state, the coarse adjustment screw is first threaded into the threaded hole to squeeze the pipe to have the distance MS between the first and second abut portions thereof at the ridge R on the upstanding portion A of the anvil to thereby set the nozzle at a flow rate slightly higher than a desired flow rate, which performs the coarse adjustment operation as shown in FIG. B. As described before, it is to be noted that the diameter of the through-apertures B and C formed in the pressing member is oversized relative to the diameter of the threaded shank portions of the fine-tuning screws while the head portion of the screw is oversized relative to the diameter of the through-apertures B and C, so that during the coarse adjustment, the pressing member is pressed against the pipe by the coarse adjustment screw alone. (See FIG. 3B.)

Once the coarse adjustment has been completed, the fine adjustment screws are threaded to conduct a fine adjustment operation. Since fine adjustment screws have head portions A, it is possible to make the thread diameter of the threaded shank portion B smaller than the diameter of the threaded shank portion of the coarse adjustment screw . By way of example, assuming that the coarse adjustment screw has a diameter of 6 mm, then the fine adjustment screws may be 3 mm in diameter at the respective threaded shank portions.

Since a thin screw having a small thread diameter is small in its thread pitch, it is possible to reduce the amount of deformation of the pipe relative to the amount of rotation of the fine adjustment screws . In this regard, the coarse adjustment screw having a diameter of 6 mm may have a thread pitch of 0.75 mm. In contrast, the fine adjustment screw having a diameter of 3 mm would have a thread pitch of 0.35 mm. It is thus to be appreciated that the amount of displacement of a screw per unit angle of rotation is reduced with a decrease in the diameter of the screw, and that the small-diameter screw allows for adequate fine adjustment.

Moreover, since the two fine adjustment screws are located at symmetrically distant positions B and C with equal distances from the center position A of the pressing member , when one of the fine adjustment screws is threaded in, the pressing member is moved in a lever-action with the other fine adjustment screw as a pivot point to squeeze down the pipe .

More specifically, as shown in FIG. 5, assuming that only the fine adjustment screw inserted in the through-aperture C is turned with the other fine adjustment screw inserted in the through-aperture B as a fixed fulcrum, for example and that the amount of pressing displacement caused by the screw at C is M, the total amount, δ of the displacement at the center position A of the pressing member at which the pipe is squeezed by the combination of the respective pressing forces due to the respective fine adjustment screws .

Accordingly, the displacement M at the point C will be reduced substantially ½ of M since the pipe is positioned at substantially ½ of the length L of the line extending between the centers (represented by B and C) of the two fine adjustment screws . Consequently, the amount of displacement M by the fine adjustment screw at the point C is further reduced to δ prior to being transmitted to the pipe , whereby the fine adjustment may be much more finely and easily facilitated.

According to the present invention, the coarse adjustment sets the orifice with a distance MS which is slightly larger than the desired value and the fine adjustment varies the distance MS to its finally desired value MSF, so that it is easily prevented from over squeezing too a much smaller value.

It should be noted that in FIG. 5 the solid line shows the pressing member being in the position prior to be subjected to the fine adjustment while the broken line shows the pressing member being in the position after it has been subjected to the fine adjustment.

As the pipe is pressed against the anvil by the pressing member , the pipe is deformed in conformity with the shape of the anvil to form an orifice decreasing in cross-sectional area progressively in the axial direction of the pipe up to the minimum cross-sectional area with the finally desired distance MSF and then progressively increasing in cross-sectional area, so that the sonic flow rate may be obtained at the point of the minimum cross-sectional area (orifice), if the required conditions (the pressure on the primary side is above a predetermined value while the pressure on the secondary side is below the predetermined value) are satisfied. The sonic flow rate is maintained constant if the pressure on the primary side is above the predetermined level even though the pressure on the secondary side varies to a certain degree. It is thus to be appreciated that a highly reliable constant flow rate may be obtained if a target flow rate is set at the sonic flow rate.

As is appreciated from the foregoing descriptions, the provision of the fine adjustment screws in addition to the coarse adjustment screw according to the present invention facilitates the setting of a flow rate. Further, according to the present invention, since the coarse adjustment screw and the fine adjustment screws are recessed in the threaded hole and the screwdriving apertures formed in the metallic block , there is no risk of changing the set flow rate inadvertently or intentionally if the hole and apertures are closed by seals or the like once the flow rate has been set. Accordingly, it is to be understood that a particular set flow value may be maintained for a long period of time to thereby provide a highly reliable reference flow rate.

While the anvil is shown as being removably mounted to the metallic block and including the upstanding portion A having a top surface AA arcuate in cross-section as viewed in axial direction X of the pipe as an example, it is to be understood that the shape of the orifice may be varied as desired by changing the cross-sectional shape of the top surface AA of the upstanding portion A to a different one.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional views illustrating one embodiment of the flow resistance setting nozzle according to this invention taken along the plane containing the X and Y axes and perpendicular to the plane of the drawing and looking in the direction B in FIG. 2, wherein FIG. 1A is taken along the plane containing the X and Y axes and perpendicular to the plane of the drawing and looking in the direction A in FIG. 3A to show the condition prior to a coarse adjustment operation is conducted by the use of the pressing member while FIG. 1B is taken along the plane containing the X and Y axes and perpendicular to the plane of the drawing and looking in the direction B in FIG. 3B to show the condition after the coarse adjustment operation has been conducted by the use of the pressing member.

FIG. 2 is a plan view of the embodiment shown in FIGS. 1A and 1B.

FIGS. 3A, B and C are cross-sectional views taken along the plane containing the Y and Z axes and perpendicular to the plane of the drawing and looking in the direction A in FIG. 2, wherein FIG. 3A is taken along the plane containing the Y and Z axes and perpendicular to the plane of the drawing and looking in the direction A in FIG. 1A to show the condition prior to the coarse adjustment operation is conducted, FIG. 3B is taken along the plane containing the Y and Z axes and perpendicular to the plane of the drawing and looking in the direction B in FIG. 1B to show the condition after the coarse adjustment operation has been conducted, and FIG. 3C shows the condition after a fine adjustment operation has been conducted.

FIG. 4A is a plan view illustrating the construction of the pressing member for use in the present invention, and FIG. 4B is a side view of the pressing member.

FIG. 5 is a diagrammatical view illustrating the principle of fine adjustment operation which forms the essential portion of the present invention by the use of the pressing member.

FIG. 6 is a cross-sectional view illustrating the known prior art flow resistance setting valve.

FIG. 7 is a block diagram illustrating the known prior art flow resistance setting valve in practical use.

CLAIMS

1. A flow resistance setting nozzle comprising a metallic block having formed therethrough a pipe receiving through-bore; a metallic pipe for forming a flow path which is inserted in the pipe receiving through-bore; a pressing member in the form of a rectangular cross-section bar orthogonally abutting at a center position thereof with the pipe at a first abut portion thereof; a coarse adjustment screw mounted in the metallic block to press the pressing member at the center position thereof against the metallic pipe by a coarse adjustment force generated by the coarse adjustment screw; an anvil having a distal end and mounted in the metallic block at a position opposite to the coarse adjustment screw such that the distal end of the anvil abuts the metallic pipe at a second abut portion thereof which is opposite to the first abut portion where the pipe abuts with the pressing member so that the pipe is received by and interposed between the pressing member and the anvil, whereby the pipe is squeezed by a coarse amount according to coarse adjustment force generated by the coarse adjustment screw; two fine adjustment screws mounted in the metallic block to press the pressing member at two symmetrically distant positions thereof which locate with substantially equal distances in longitudinally opposite directions of the pressing member from the center position thereof against the metallic pipe by a fine adjustment force which is obtained from combination of respective pressing forces generated by the respective fine adjustment screws and which is additive to the coarse pressing force generated by the coarse adjustment screw, whereby the pipe is further squeezed by a fine amount according to the fine adjustment force; and seal means for forming seals between the outer peripheral surface of the metallic pipe and the inner peripheral wall of the pipe receiving through-bore formed in the metallic block.

2. The flow resistance setting nozzle according to claim 1, wherein the metallic block has a pressing member receiving bore which is formed therein to orthogonally intersect the pipe receiving through-bore, the pressing member is inserted in the pressing member receiving bore such that the pressing member orthogonally abuts with the pipe at the first abut portion.

3. The flow resistance setting nozzle according to claim 1, wherein each of the fine adjustment screws has a head portion and a threaded shank portion; the pressing member has two through-apertures formed therethrough at the two symmetrically distant positions for loosely receiving the threaded shank portions of the corresponding fine adjustment screws therethrough; and the metallic block having two threaded holes which are coaxial with the two through-apertures and in which the threaded shank portions of the corresponding fine adjustment screws are threaded; whereby the fine adjustment force is obtained from combination of the respective pressing forces imparted by the head portions of the fine adjustment screws to the pressing member as the threaded shank portions of the fine adjustment screws loosely fitted in the through-apertures of the pressing member are threaded into the threaded holes in the metallic block.

4. The flow resistance setting nozzle according to claim 2, wherein each of the fine adjustment screws has a head portion and a threaded shank portion; the pressing member has two through-apertures formed therethrough at the two symmetrically distant positions for loosely receiving the threaded shank portions of the corresponding fine adjustment screws therethrough; and the metallic block having two threaded holes which are coaxial with the two through-apertures and in which the threaded shank portions of the corresponding fine adjustment screws are threaded; whereby the fine adjustment force is obtained from combination of the respective pressing forces imparted by the head portions of the fine adjustment screws to the pressing member as the threaded shank portions of the fine adjustment screws loosely fitted in the through-apertures of the pressing member are threaded into the threaded holes in the metallic block.

5. The flow resistance setting nozzle according to claim 3, wherein each of the threaded shank portions of the fine adjustment screws has a diameter smaller than that of a threaded shank portion of the coarse adjustment screw.

6. The flow resistance setting nozzle according to claim 4, wherein each of the threaded shank portions of the fine adjustment screws has a diameter smaller than that of a threaded shank portion of the coarse adjustment screw.

7. The flow resistance setting nozzle according to claim 1, wherein the distal end of the anvil has an arcuate surface with a top ridge thereof oriented in a direction orthogonal to the longitudinal direction of the pipe so that the arcuate surface of the anvil intersects the cylindrical peripheral surface of the pipe as the second abut portion.

8. The flow resistance setting nozzle according to claim 2, wherein the distal end of the anvil has an arcuate surface with a top ridge thereof oriented in a direction orthogonal to the longitudinal direction of the pipe so that the arcuate surface of the anvil intersects the cylindrical peripheral surface of the pipe as the second abut portion.

9. The flow resistance setting nozzle according to claim 1, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block respectively.

10. The flow resistance setting nozzle according to claim 2, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

11. The flow resistance setting nozzle according to claim 3, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

12. The flow resistance setting nozzle according to claim 4, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

13. The flow resistance setting nozzle according to claim 5, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

14. The flow resistance setting nozzle according to claim 6, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

15. The flow resistance setting nozzle according to claim 7, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

16. The flow resistance setting nozzle according to claim 8, wherein the metallic block has a coarse threaded hole and two screwdriving apertures formed therein, and the respective head portions of the coarse adjustment screw and two fine adjustment screws are recessed in the coarse threaded hole and the two screwdriving apertures formed in said metallic block, respectively.

17. A flow resistance setting nozzle comprising a metallic block having formed therein a pipe receiving through-bore, a pressing member receiving bore, a coarse threaded hole, two screwdriving apertures, two fine threaded holes, and an anvil mounting bore; a metallic pipe for forming a flow path; a pressing member; an anvil; a coarse adjustment screw; two fine adjustment screws; and seal means; wherein the pressing member receiving bore is extended to orthogonally intersect to the pipe receiving through-bore; the coarse threaded hole is extended to orthogonally intersect to the pipe receiving through-bore and the pressing member receiving bore; the anvil mounting bore is extended to orthogonally intersect to the pipe receiving through-bore in opposition to the coarse threaded hole; the two screwdriving apertures are extended in parallel to the coarse threaded hole to orthogonally intersect to the pressing member receiving bore at symmetric positions with respect to the coarse threaded hole; the two fine threaded holes are extended coaxially with the two screwdriving apertures to orthogonally intersect to the pressing member receiving bore; the metallic pipe is inserted in the pipe receiving through-bore; the pressing member is in the form of a rectangular cross-section bar having two spaced through-apertures at symmetric positions with respect to its center position and is inserted in the pressing member receiving bore to orthogonally abut at the center position thereof with the metallic pipe at a first abut portion thereof; the anvil is inserted in the anvil mounting bore to support the metallic pipe at a second abut portion opposite to the first abut portion as the pipe is pressed by the pressing member; the coarse adjustment screw is threaded in the coarse threaded hole to press the pressing member at the center position thereof by a coarse adjustment force generated by the coarse adjustment screw against the metallic pipe to thereby squeeze the pipe by a coarse amount according to the coarse adjustment force; each of the two fine adjustment screws comprises a head portion and a threaded shank portion which is loosely fitted in each the through-aperture in the pressing member and threaded into each of the two fine threaded holes to impart a further fine pressing force to the pressing member to thereby further squeeze the metallic pipe by a fine amount according to a fine adjustment force obtained from combination of the respective pressing forces generated by the respective fine adjustment screws; and the seal means forms air-tight sealing which allows the metallic pipe to be coupled to outer equipment outside of the metallic block.

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