WEFT INSERTION PUMP FOR WATER JET LOOM

BACKGROUND OF THE INVENTION

The present invention relates to a weft insertion pump for a water jet loom.

A water jet loom is equipped with a weft insertion pump. The weft insertion pump has a pump housing which is formed with an integral water storage chamber forming cylinder in which a plunger is slidably received. The pump housing has formed therethrough suction and discharge ports and a water storage chamber is formed between the suction and the discharge ports. The water storage chamber and the interior of the water storage chamber forming cylinder communicate with each other. A suction-side check valve is interposed between the water storage chamber and the suction port and a discharge-side check valve is interposed between the water storage chamber and the discharge port. The suction port is connected to a water tank through a suction pipe and the discharge port is connected to a water insertion nozzle through a discharge pipe.

When the plunger is moved away from the water storage chamber, the water storage chamber is increased in volume to generate therein a suction pressure. Such suction pressure generated in the water storage chamber, suction force for drawing water stored in the water tank causes the suction-side check valve to open, thereby drawing water stored in the water tank into the water storage chamber. At this time, the discharge-side check valve is closed to prevent water in the discharge pipe from being flowed back into the water storage chamber. When the plunger is moved toward the water storage chamber, on the other hand, the water stored in the water storage chamber is pressurized by the plunger. Accordingly, the suction-side check valve is closed and the discharge-side check valve is opened and then the pressurized water in the water storage chamber is fed to the weft insertion nozzle through the discharge pipe. The water fed to the weft insertion nozzle is injected from the weft insertion nozzle and a weft is inserted by a water jet into a warp shed.

Referring to FIG. 8 showing a suction-side check valve or a discharge-side check valve of a weft insertion pump in a water jet loom, the suction-side check valve 100A or the discharge-side check valve 1008 includes a spherical-shaped valve body 101, a disk-shaped valve seat member 102 and a cylindrical stop member 103. The valve seat member 102 has a valve seat 102E on which the valve body 101 may be seated. The cylindrical stop member 103 has a stop surface 103E regulating the moving distance of the valve body 101 from the valve seat 102E of the valve seat member 102. The valve seat member 102 is mounted to the stop member 103 so as to close the opening of the stop member 103. A suction passage 102A is formed through the valve seat member 102 at the center thereof. The valve seat 102E has a diameter gradually reduced as being away from the valve body 101 and is formed by a conical surface which is continuously connected to the suction passage 102A.

Referring to FIG. 9, the stop member 103 has a plurality of guide walls 103A spaced at an angular interval for slidably guiding the valve body 101 movable in the axial direction of the stop member 103. Communication passages 103B are formed between any two adjacent guide walls 103A in the circumferential direction of the stop member 103 and water in the suction passage 102A is flowed through the communication passage 103B.

When suction pressure is generated in the water storage chamber 105, the valve body 101 is moved into contact with the stop surface 103E, as shown in FIG. 10, thereby allowing water in the suction passage 102A to flow into the communication passages 103B through a space formed between the valve seat 102E and the valve body 101. Since the space between the valve seat 102E and the valve body 101 is a small clearance, the water flowing through the space from the suction passage 102A increases its flow rate and is rushed into the respective communication passages 103B. In the check valve 100A, 100B, water flow hardly occurs in the regions Z, there are corners of the communication passage 103B away from the valve seat 102E and indicated by shading in FIG. 9, therefore, water tends to stay in the regions Z without flowing.

Significant difference flow rate between the water staying in region Z and the water staying around the region Z in the communication passages 103B causes a chock wave. Any impact of the shock wave transmitted to the end surface of the valve seat member 102 exposed to the communication passages 103B causes a fear that erosion occurs the above end surface of the valve seat member 102.

In the check valve of a weft insertion pump in a water jet loom disclosed in the above Japanese Patent Application Publication No. 2005-3034, the valve seat member 102 is made of zirconia-based ceramic formed by HIP (hot isostatic pressing) process. By using such valve seat member 102 made of zirconia-based ceramic formed by HIP process, the erosion of the above end surface of the valve seat member 102 is suppressed, so that the lifetime of the valve seat member 102 is increased.

However, the valve seat member 102 is made of zirconia-based ceramic formed by HIP process is expensive and, therefore, the manufacturing cost of the weft insertion pump using such valve seat member is increased.

The present invention is directed to providing a weft insertion pump for a water jet loom which suppresses erosion of a valve seat member of a suction-side check valve with an inexpensive structure.

SUMMARY OF THE INVENTION

In accordance with the present invention, a weft insertion pump for a water jet loom includes a pump housing, a water storage chamber forming cylinder, a plunger, discharge and suction ports, a water storage chamber, a water tank, a weft insertion nozzle, a discharge-side check valve, a suction-side check valve and a stop member. The water storage chamber forming cylinder is disposed within the pump housing. The plunger is slidably received in the water storage chamber forming cylinder. The discharge and suction ports are formed in the pump housing and connected to a weft insertion nozzle and a water tank, respectively. The water storage chamber is formed between the suction and discharge ports. The discharge-side check valve is interposed between the water storage chamber and the discharge port. The suction-side check valve is interposed between the water storage chamber and the suction port. The suction-side check valve includes a valve body having a spherical shape, a valve seat member having a valve surface and a stop member having a cylindrical shape. A suction passage is formed through the valve seat member. The stop member includes a stop part configured to regulating moving distance of the valve body away from the valve surface of the valve seat member. The stop member is formed with a plurality of guide walls which are spaced at an angular interval. The guide walls are configured to slidably guide the valve body in an axial direction of the stop member. Communication passages are formed in a circumferential direction of the stop member between any two adjacent guide walls. Water from the suction passage is flowed through the communication passages. An annular groove is formed in the valve seat member so as to surround and be continuously connected to the valve surface for providing fluid communication between the communication passages.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a schematic view of a weft insertion apparatus for a water jet loom, showing a weft insertion pump according to a preferred embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of the weft insertion pump in FIG. 1;

FIG. 3 is an enlarged sectional view of a suction-side check valve of the weft insertion pump in FIG. 1, showing the sate where a valve body of the suction-side check valve is seated on a valve seat of the suction-side check valve;

FIG. 4 is a plan view of the suction-side check valve of the weft insertion pump in FIG. 1 as viewed from stop member side;

FIG. 5 is a plan view of a valve seat member of the suction-side check valve of the weft insertion pump in FIG. 1 as viewed from the valve seat side;

FIG. 6 is an enlarged sectional view of the suction-side check valve of the weft insertion pump in FIG. 1, showing the state where the valve body of the suction-side check valve is spaced away from the valve seat;

FIG. 7 is an enlarged sectional view of the suction-side check valve of a weft insertion pump for a water jet loom according to another preferred embodiment;

FIG. 8 is a sectional view of the suction-side check valve and the discharge-side check valve of the weft insertion pump for a water jet loom according to the background art;

FIG. 9 is a plan view of the suction-side check valve and the discharge-side check valve of the weft insertion pump according to the background art; and

FIG. 10 is a sectional view of the suction-side check valve of the weft insertion pump according to the background art, showing a state where the valve body of the suction-side check valve is spaced away from the valve seat of the suction-side check valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe a weft insertion apparatus for a water jet loom according to a first preferred embodiment of the present invention with reference to FIGS. 1 through 6. Referring to FIG. 1, reference numeral 10 designates a weft insertion apparatus for a water jet loom (hereinafter referred to merely as “weft insertion apparatus”). The weft insertion apparatus 10 has a weft insertion pump 11. The weft insertion pump 11 is connected to a weft insertion nozzle 13 through a discharge pipe 12 and to a water tank 15 through a suction pipe 14. The weft insertion pump 11 draws water from the water tank 15 through the suction pipe 14 and delivers the pumped water to the discharge pipe 12.

Referring to FIG. 2, the weft insertion pump 11 has a pump housing 20 and a water storage chamber forming cylinder 21 is disposed within the pump housing 20. A plunger 22 is slidably received in the water storage chamber forming cylinder 21. A spring seat 22A is mounted around the water storage chamber forming cylinder 21 and a spring cap 22B is screwed in the pump housing 20. The spring cap 22B is fixed to the pump housing 20 by a locknut 22C. The spring seat 22A has a seat portion 221A and the spring cap 22B also has a seat portion 221B and a coil spring 22D is interposed between the seat portions 221A, 221B of the spring seat 22A and the spring cap 22B.

The pump housing 20 has formed therein a suction port 23 and a discharge port 24. A water storage chamber 25 is formed between the suction and the discharge ports 23 and 24. The water storage chamber 25 communicates with the interior of the water storage chamber forming cylinder 21. A suction-side check valve 30A is interposed between the water storage chamber 25 and the suction port 23 and a discharge-side check valve 30B is interposed between the water storage chamber 25 and the discharge port 24. The suction port 23 is connected to the water tank 15 through the suction pipe 14 and the discharge port 24 is connected to the weft insertion nozzle 13 through the discharge pipe 12.

As shown in FIG. 1, the weft insertion apparatus includes a drive shaft 16, a cam 17, a cam lever 18, a support shaft 18A, a cam follower 18B and a linkage 19. The cam 17 is fixedly mounted on the drive shaft 16 driven by a drive motor (not shown). The cam lever 18 is rotatably supported by the support shaft 18A disposed parallel to the drive shaft 16. The cam lever 18 is capable of being in contact with and separated from the cam 17 through the cam follower 18B. The cam lever 18 is swingable reciprocally by the cooperative operation of the cam 17 rotatable in arrow direction R in FIG. 1 at a constant angular speed and the coil spring 22D disposed in the weft insertion pump 11. The plunger 22 of the weft insertion pump 11 is connected to the cam lever 18 through the linkage 19. The plunger 22 and the spring seat 22A are integrally reciprocated by the reciprocating motion of the cam lever 18.

When the cam lever 18 is turned counterclockwise as seen in FIG. 1 around the support shaft 18A by the operation of the cam 17, the plunger 22 and the spring seat 22A of the weft insertion pump 11 are moved leftward in FIG. 2 against the spring force of the coil spring 22D. The leftward movement of the plunger 22 with the spring seat 22A while compressing the coil spring 22D causes a predetermined volume of water to be pumped into the water storage chamber 25 from the water tank 15 through the suction pipe 14. The suction-side check valve 30A is opened and the discharge-side check valve 30B is closed while water is being pumped from the water tank 15 into the water storage chamber 25, so that the water present in the discharge pipe 12 is prevented from flowing back into the water storage chamber 25.

The cam 17 has a cam surface 17A. When the cam follower 18B moves past the maximum diameter position N of the cam surface 17A shown in FIG. 1, the cam follower 1813 is positioned away from the cam surface 17A and the plunger 22 is moved by the urging force of the coil spring 22D in the direction that pressurizes the water in the water storage chamber 25. When water in the water storage chamber 25 is pressurized to a predetermined level, the suction-side check valve 30A is closed and the discharge-side check valve 30B is opened thereby to feed the pressurized water in the water storage chamber 25 to the weft insertion nozzle 13 through the discharge pipe 12. The water fed to the weft insertion nozzle 13 is injected therefrom and a weft Y is inserted into a warp shed (not shown). When the cam follower 18B is positioned in contact with the cam surface 17A or a stop 29 which is provided for regulating the discharge volume of water, one cycle of water injecting which is a time period of insertion of weft Y is ended.

The following will describe the structure of the suction-side check valve 30A in detail. The structure of the discharge-side check valve 30B is substantially the same as the suction-side check valve 100A and the discharge-side check valve 100B described with reference to the background art of the present invention and, therefore, the description the discharge-side check valve 30B of this preferred embodiment will be omitted.

Referring to FIG. 3, the suction-side check valve 30A includes a spherical valve body 31, a valve seat member 32 and a stop member 33. The valve seat member 32 is of a disk shape and has a valve surface 32E on which the valve body 31 may be seated. The stop member 33 is of a cylindrical shape and has a stop surface 33E regulating the moving distance of the valve body 31 away from the valve surface 32E of the valve seat member 32. The stop surface 33E serves as a stop part of the present invention. The valve seat member 32 is mounted to the stop member 33 so as to close the opening of the stop member 33. A suction passage 32A is formed through the valve seat member 32 at the center thereof.

The valve surface 32E of the valve seat member 32 has a diameter gradually reduced as being away from the valve body 31 and is formed by a conical surface which is continuously connected to the suction passage 32A.

Referring to FIG. 4, the stop member 33 is formed on the inner peripheral surface thererof with a plurality of guide walls 33A (three guide walls in this preferred embodiment) which are spaced at an angular interval and slidably guides the valve body 31 in the axial direction of the stop member 33. Communication passages 33B are formed between any two adjacent guide walls 33A in the circumferential direction of the stop member 33, through which water from the suction passage 32A is flowed. A hole 331E is formed axially in the stop surface 33E at the center thereof.

Referring to FIG. 5, an annular groove 32B is formed in the valve seat member 32 so as to surround and be continuously connected to the valve surface 32E for providing fluid communication between the communication passages 33B. The annular groove 32B has an outer peripheral edge 321B and each communication passage 33B has an outer peripheral edge 331B. The outer peripheral edges 321B and 331B are in continuity with each other in the axial direction of the stop member 33. Deviation between the annular groove 32B and the communication passage 33B due to the tolerances of the annular groove 32B and the communication passages 33B is allowable.

The following will describe the operation of the weft insertion pump in the weft insertion apparatus 10 of this preferred embodiment of the present invention. When suction pressure is generated in the water storage chamber 25 by the leftward movement of the plunger 22 and the spring seat 22A of the suction-side check valve 30A as seen in FIG. 2, the valve body 31 is moved into contact with the stop surface 33E of the stop member 33, as shown in FIG. 6. Accordingly, water present in the space between the valve body 31 and the stop surface 33E is flowed into the water storage chamber 25 through the hole 331E. Then, the water present upstream of the suction-side check valve 30A is drawn into the communication passage 33B through the suction passage 32A and the space formed between the valve surface 32E and the valve body 31.

Since the space between the valve surface 32E and the valve body 31 is a small clearance, the water flowing through the space increases its flow rate and is rushed into the respective communication passages 33B. If the valve seat member 32 had no annular groove 32B, water flow hardly occurs in the regions Z that are corners of the communication passage 33B away from the valve surface 32E and indicated by shading in FIG. 4 and, therefore, the water tends to stay in the regions Z.

In the suction-side check valve 30A, water is flowed from the valve surface 32E to the communication passages 33B through the annular groove 32B and also from the guide walls 33A to the communication passages 33B, so that the water is prevented from staying in the region Z and the shock wave which is caused by large difference between the flow rates of the water staying in region Z and the water flowing around the region Z in the communication passages 33B is suppressed. Therefore, the erosion of the end surface of the valve seat member 32 facing the communication passages 33B caused by the shock wave transmitted to the end surface is prevented.

This preferred embodiment offers the following advantageous effects.

(1) The annular groove 32B is formed in the valve seat member 32 of the suction-side check valve 30A so as to surround and be continuously connected to the valve surface 32E for providing fluid communication between the communication passages 33B. In such structure of the suction-side check valve 30A, water is flowed from the valve surface 32E to the communication passages 33B through the annular groove 32B and also flowed from the guide walls 33A to the communication passages 33B, so that water is prevented from staying in the region Z and the shock wave caused by the large difference between the flow rates of the water staying in region Z and the water flowing around the region Z in the communication passages 33B is suppressed. Therefore, the erosion of the end surface of the valve seat member 32 facing the communication passages 33B caused by the shock wave transmitted to the end surface may be suppressed. According to the embodiment of the present invention, the valve seat member 32 does not need to be made of zirconia-based ceramic formed by HIP (hot isostatic pressing) process to suppress the erosion of the valve seat member 32, but the suppression of the erosion of the valve seat member 32 of the suction-side check valve 30A may be accomplished by an inexpensive structure.

(2) The outer peripheral edge 321B of the annular groove 32B and the outer peripheral edge 331B of the communication passages 33B are in continuity with each other in the axial direction of the stop member 33. If the outer peripheral edge 321B of the annular groove 32B is positioned inward of the outer peripheral edge 331B of the communication passages 33B without being in continuity therewith, steps are formed between the annular groove 32B and the communication passages 33B and, therefore, there is a fear that cavitation occurs in the communication passages 33B. With the outer peripheral edge 321B of the annular groove 32B and the outer peripheral edges 331B of the communication passages 33B are in continuity with each other in the axial direction of the stop member 33, no step is formed between the annular groove 32B and the communication passages 33B, so that occurrence of the cavitation may be prevented and the erosion of the valve seat member 32 of the suction-side check valve 30A may be suppressed easily.

(3) The annular groove 32B is formed in the valve seat member 32 so as to surround the valve surface 32E and to be continuously connected to the valve surface 32E for communication between the communication passages 33B. If a recess is formed in the stop member 33 at the end surface of the guide walls 33A facing the valve seat member 32, a burr is easily formed in the stop member 33 at a position where the recess is connected to the guide walls 33A and the surfaces of the communication passages 33B and there is a fear that the burr causes the cavitation. Since the valve seat member 32 has no complicated portions such as the guide wall 33A and the communication passage 33B of the stop member 33, the provision of the annular groove 32B in the valve seat member 32 causes no cavitation in the valve seat member 32 due to any burr.

The above-described preferred embodiment may be modified as follows.

Referring to FIG. 7 showing an alternative embodiment, the annular groove 32B may be formed by providing an annular member 40 between the valve seat member 32 and the stop member 33. In this case, the annular groove 32B may be formed without machining the valve seat member 32.

The outer peripheral edge 321B of the annular groove 32B may be formed outward or inward of the outer peripheral edge 331B of the communication passage 33B. That is, the outer peripheral edge 321B of the annular groove 32B and the outer peripheral edge 331B of the stop member 33 may not be in continuity with each other in the axial direction of the stop member 33.

According to the present invention, the numbers of the guide walls 33A and the communication passages 33B are not specifically limited.

WEFT INSERTION PUMP FOR WATER JET LOOM

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