VALVE HAVING VALVE BODY OF CERAMIC COMPOUND

Abstract: A valve provided with a fixed valve body (13) forming a fluid passage, and a movable valve body (14) arranged so that the valve body (14) can be moved with respect to and in contact with the fixed valve body (13). In order to carry out the sliding of the movable valve body (14) with respect to the fixed valve body (13) smoothly for a long period of time, the sliding surface of at least one of these valve bodies (14), (15) is formed of a ceramic compound which consists of a sin­ tered ceramic material having opened pores of three-­ dimensional reticulate construction, and a lubricating mate­ rial packed in these open pores. Owing to the above, the fluid passage opening and closing operations can be car­ ried out lightly and stably at all times by an operating lever (17), and the sliding movement of the valve body (14) with respect to the fixed valve body (13) can be maintained for a long period of time with the valve body (14) kept in close contact with the valve (13). Accordingly, the leakage of the fluid does not occur.

Description: This invention relates to valves provided with valve bodies made of a ceramic compound for connecting and disconnecting a passage of a fluid and more particularly to a valve provided with valve bodies made of a ceramic compound charged with a lubricant in the open pores of a porous sintered ceramic body. There have been already suggested many valves wherein, by operating an operating lever, a movable valve body is moved relatively in sliding contact with a fixed valve body contained in a main valve body to connect or disconnect a passage of a fluid or, in other words, to control the valve to be opened, closed, switched, adjusted or used to mix fluids. Now, for this kind of valve, there are such various requirements as in the following: (1) Even though the movable valve body is always in sliding contact with the fixed valve body, the movable valve body should be lightly operated by the operating lever. (2) The operation by the operating lever should be able to be maintained to be light for a long period. (3) The maintenance service of each valve body should be simple and, if possible, should not be required at all. (4) As a matter of course, the sealing between the respective valve bodies should not vary and the fluid should not leak out even in a long use. (5) The respective valve bodies should be simple to make. In such various already suggested valves for fluids as, for example, valves for mixing hot water and cold water with each other, in consideration of the wear resistance between the respective valve bodies, the respective valve bodies have been often formed of such comparatively hard material as a metal or sintered aluminum oxide so as to be compact. However, if so formed, the respective valve bodies will improve in the wear resistance but will not smoothly slide between them and, as shown in Fig. 4, the sliding torque applied to the operating lever of the valve for mixing hot water and cold water will be considerably large in the initial period. Therefore, in order to smooth such sliding, the respective valve bodies are painted with a lubricant on the surfaces. However, the lubricant applied to paint the surface is so likely to flow out that, in the case of a long use, it will be difficult to maintain the initial operation characteristic. Thus, ceramics themselves have a high hardness and are high in the wear resistance but are generally poor in the self-lubricatability. Ceramics have not yet been suggested as materials for solving this problem and application to valves. JP-A-52-35109 discloses a process for preparing sliding members of porous sintered metal impregnated with a solid lubricant. The sliding members may be parts of a cock plug. JP-A-59-232981 discloses a sliding material of ceramic having voids in its outer layer which are filled with a solid lubricant. JP-A-118080 discloses porous ceramic bearings impregnated with PTFE. The present invention is made in view of such fact as in the above and its object is to provide a valve wherein, even in the case of a long use, the fluid can be always lightly and stably connected or disconnected by the operating lever. Disclosure of the Invention: The present invention provides a valve provided with valve bodies comprising: a fixed valve body, made of ceramics, constituting a part of a fluid passage between an inlet source and an outlet source; and a movable valve body, made of ceramics, in slidable face-to-face sealing contact with said fixed valve body for connecting and disconnecting said fluid passage between said inlet source and said outlet source whilst maintaining said face-to-face sealing contacting condition, wherein at least one of said fixed valve body and said movable valve body is composed of sintered silicon carbide ceramics body having three-dimensional open pores filled with liquid lubricant oil; said impregnated ceramics body presenting a sliding contact surface formed of both said liquid lubricant oil and said ceramics; said open pores is 5 to 40% by volume. Now, the ceramic compound of the present invention can be made by a process wherein a ceramic powder which is a starting material is formed to be of a produced form of any shape, is bonded to be a porous ceramic body without closing the pores present in the produced form and is then charged with a lubricant in the open pores of the above-mentioned porous ceramic body. For the process wherein the above-mentioned ceramic powder is formed to be of a produced form of any shape and is bonded without closing the pores present in the produced form, there can be applied such various methods as, for example, a method wherein a ceramic powder itself is sintered under the normal pressure or an added pressure to be self-sintered, a method wherein a ceramic powder is made to react to be sintered by adding a substance producing ceramics by reaction, a method wherein a ceramic powder is mixed with such metal as Co, Ni or Mo or such binder as a glass cement and is sintered under the normal pressure or an added pressure to be bonded and a method wherein a ceramic powder is mixed with such binder as a thermosetting resin or thermoplastic resin so as to be bonded. It is advantageous for the above mentioned sintered ceramic body that the rate of the open pores is 5 to 40% by volume, because, if the above mentioned rate of the open pores is lower than 5% by volume, the substantial charge of the lubricant will be so low that it will be difficult to sufficiently develop the lubricating characteristic and, on the other hand, if it is higher than 40% by volume, the sintered body will be low in the strength and durability. It is advantageous that the average granule diameter of the crystals of the above mentioned sintered ceramic body is less than 10 µm, because, if the average granule diameter of the above mentioned crystals is larger than 10 µm, the coarseness of the surface of the sintered body will be likely to be so large as to reduce the sliding characteristic. It is advantageous that the average granule diameter of the ceramic powder which is the above mentioned starting material is less than 10 µm, because, if a ceramic powder of an average granule diameter larger than 10 µm is used, the bonding parts between the granules will be so few that not only it will be difficult to produce a sintered body of a high strength but also the surface coarseness will deteriorate. For the lubricant with which the above mentioned sintered ceramic body is to be charged, there can be used any of a resin having a lubricating property, fluorine type oil, silicone type oil and lubricating oil. For the above mentioned resin having a lubricating property, there can be used any one or mixture of more resins selected from among a polyacetal resin, polyamide resin, polyethylene resin, polycarbonate resin, polybutylene terephthalate resin, styrene acrylonitrile resin, polypropylene resin, polyurethane resin, polyphenylene sulfide resin, epoxy resin, silicone resin and fluorine resin. For the above mentioned fluorine type oil, it is advantageous to use any one or mixture of more selected from among fluoroethylene, fluoroester, fluorotriazine, perfluoropolyether, fluorosilicone, their derivatives and polymers. For the above mentioned silicone type oil, it is advantageous to use any one or mixture of more selected from among methyl silicone, methylphenyl silicone, their derivatives and polymers. The above mentioned fluorine type oil and silicone type oil can be used in the form of any of a liquid, grease and wax. Moreover the above mentioned fluorine type oil and silicone type oil are so high in the solventproofness, chemical stability and heatproofness as to be able to give a very high lubricating characteristic over a long time. According to the present invention, it is advantageous to impregnate or charge 100 parts by volume of the open pores of the above mentioned sintered ceramic body with at least 10 parts by volume of the lubricant, because, if the impregnation or charge with the lubricant is less than 10 parts by volume, it will be difficult to substantially develop the lubricating effect. For the process of impregnating or charging the open pores of the above mentioned sintered ceramic body with a lubricant, there can be applied a method wherein the sintered ceramic body is dipped in the lubricant heated to be melted or reduced in the viscosity in a vacuum or under an added pressure, a method wherein it is dipped in the lubricant dissolved by a solvent. A valve according to the present invention is formed as mentioned above and therefore has such operation as is mentioned in the following. First of all, as the sliding surface part of at least either of the fixed valve body and movable valve body is formed of a porous sintered ceramic body, this sintered ceramic body itself is so high in the hardness and wear resistance that these fixed valve body and movable valve body are high in the wear resistance. Also, as the sliding surface part of at least either of the fixed valve body and movable valve body is formed of a sintered ceramic body having open pores of a three-dimensional network structure and the open pores are charged with a lubricant, the fixed valve body and movable valve body are in smooth sliding contact with each other due to the lubricating property of this lubricant. In specific embodiments, the above mentioned fixed valve body or movable valve body was formed of a sintered silicon carbide body and these valve bodies were combined within a plug for mixing hot water and cold water, the actual lubricating characteristics were as in Fig. 4 when considered from the experiment results. In these experiments, the lubricating property on the sliding contact surface of the fixed valve body and movable valve body was detected by measuring the sliding torque fluctuation in the operating lever of the plug for mixing hot water and cold water. According to these experiments, even when the operating lever was moved 100,000 times, the sliding torque (d and e in Fig. 4) was always below 5 kg cm and the sliding torque fluctuation range was below 2 to 2.5 kg cm. That is to say, as compared with the sliding torque fluctuation (a and b in Fig. 4) of the operating lever in the conventional hot water and cold water mixing plug, in case the valve bodies according to the present invention are used, the sliding torque applied to the operating lever not only will be small but also will little fluctuate even if the lever is used over a long time. Needless to say, the above is the same with such fluids as such liquids as oils, washing liquids and solvents and various gases. Even in case such other sintered ceramic body as a sintered body containing mostly one or more selected from among Al₂O₃, SiO₂, ZrO₂, SiC, TiC,TαC, B₄C, WC, Cr₃C₂, Si₃N₄, BN, TiN, AlN, TiB₂, CrB₂ and their compounds is used in place of the above mentioned sintered silicon carbide body, substantially the same operation as the above mentioned operation will be obtained. In such valve, as the fixed valve body or movable valve body itself contains a lubricant having a lubricating property, such maintenance service as of painting each valve body with a lubricant as in the past is not required at all. Brief Explanation of the Drawings: Fig. 1 is a vertically sectioned view of a hot water and cold water mixing plug embodying the present invention. Fig. 2 is a vertically sectioned view showing the relation between a fixed valve body and movable valve body. Fig. 3 is a perspective plan view of Fig. 2 as seen from above. Fig. 4 is a graph showing the sliding torque fluctuation between the fixed valve body and movable valve body according to the present invention and between the conventional fixed valve body and movable valve body as compared with each other. Figs. 5 to 10 show the present invention as applied to a single water plug. Fig. 5 is a vertically sectioned view of this single water plug. Fig. 6 is a perspective view of the fixed valve body and movable valve body. Figs. 7 and 8 are plan views showing the relation between the fixed valve body and movable valve body. Fig. 9 is a perspective view showing further another embodiment of the movable valve body. Fig. 10 is a plan view showing the relation between the fixed valve body and movable valve body. Best Form for Embodying the Invention: An example of the valve according to the present invention as applied to a fixed valve body 13 or movable valve body 14 in a plug 10 for mixing hot water and cold water shall be explained with reference to the drawings. A vertically sectioned view of the hot water and cold water mixing plug 10 is shown in Fig. 1. This hot water and cold water mixing plug is to lead cold water or hot water fed to it out of a faucet 18 as alone or properly mixed. A supporting member 12 is contained within a main valve body 11 of this plug 10, a fixed valve body 13 is arranged as fixed on this supporting member 12 and further a movable valve body 14 is arranged on this fixed valve body 13. A connecting member 15 is fixed to the upper part of the movable valve body 14 so that, when an actuating lever 16 engaged with this connecting member 15 is moved by an operating lever 17, the movable valve body 14 will be able to be slid forward, rearward, rightward and leftward in close contact with the fixed valve body 13. Needless to say, the above mentioned supporting member 12 with the fixed valve body 13 and the movable valve body 14 with the connecting member 15 may be respectively integrally formed in the embodiment. In such case, the sliding contact surface part of these integral formations may be formed of a porous sintered ceramic body having open pores of a three-dimensional network structure as described later and by charging the open pores with a lubricant. The fixed valve body 13 and movable valve body 14 are as shown in Figs. 2 and 3 and have respectively one or more passages 13a or 14a formed therein. The number and positions of these passages 13a and 14a are so set that, when the movable valve body 14 is moved in sliding contact with the fixed valve body 13 by the operation of the operating lever cold water and hot water may be selectively mixed. Needless to say, these passages 13a and 14a may be through holes or mere recesses. In Fig. 5 is shown a vertically sectioned view of a single water plug 20 in which the fixed valve body 13 and movable valve body 14 according to the present invention are used. In this single water plug 20, the fixed valve body 13 is arranged through a packing above a partition wall 23 between a primary side passage 21 and secondary side passage 22 of water and further the movable valve body 14 is arranged on the fixed valve body 13. This movable valve body 14 is to be rotated in close contact with the fixed valve body 13 by the operation of an operating lever 27 provided on a main valve body 24 of the single water plug 20 and has on the lower surface a recess 14b for selectively connecting or disconnecting a pair of passages 13a of the fixed valve body 13 as shown in Fig. 6. That is to say, in case the recess 14b is in such position relation as is shown in Fig. 17 with respect to the respective passages 13a of the fixed valve body 13, the primary side passage 21 and secondary side passage 22 will be able to be disconnected with each other and, in case the recess 14b is in such position relation as is shown in Fig. 8, the primary side passage 21 and secondary side passage 22 will be able to be connected with each other. By the way, as shown in Fig. 9, a disconnecting projection 14c which can cover the respective passages 13a of the fixed valve body 13 may be formed on the lower surface of the movable valve body 14 to form a passage 14d around it so that, when this disconnecting projection 14c is in such position relation as is shown by the solid line in Fig. 10 with respect to the respective passages 13a, the primary side passage 21 and secondary side passage 22 may be connected with each other but, when the disconnecting projection 14c is in the position relation shown by the imaginary line in Fig. 10, the primary side passage 21 and secondary side passage 22 may be disconnected with each other. The sliding contact surface part of at least either of such fixed valve body 13 and movable valve body 14 as are explained above is formed of a porous sintered ceramic body having open pores of a three-dimensional network structure and the above mentioned open pores are charged with a lubricant. Also, according to the present invention, in the case of charging the pores of the porous body with the above mentioned lubricant, if the pores are charged with the lubricant as mixed with such powder as of molybdenum bisulfide, tungsten bisulfide, molybdenum selenide, tungsten selenide or boron nitride, the sliding characteristic will be able to be further improved. Examples and a control of actually making the respective fixed valve body 13 and movable valve body 14 mostly of silicon carbide as ceramics shall be explained in the following: CONTROL 1: The silicon carbide powder used as a starting material consisted of 94.6% by weight of β type crystals, contained mostly 0.29% by weight free carbon, 0.17% by weight oxygen, 0.03% by weight iron and 0.03% by weight aluminum, had an average granule diameter of 0.28 µm and had no boron detected. 100 parts by weight of the silicon carbide powder were blended with 5 Parts by weight of polyvinyl alcohol and 300 parts by weight of water, were mixed for 5 hours in a ball mill and were then dried. A proper amount of this dried mixture was taken out, was granulated and was then molded under a pressure of 294 MPa (3000 kg/cm²) by using a pressing die made of a metal. This produced molding was of dimensions of 50mm × 50mm × 30mm and a density of 2.0 g/cm³ (62% by volume). The above mentioned produced molding was put into a crucible made of graphite and was fired in an atmosphere mostly of argon gas under 1 atmosphere by using a Tammam type furnace. In the temperature elevating process, first the temperature was elevated to 2000 o C at 450 o C/hour and the maximum temperature of 2000 o C was maintained for 10 minutes. The partial pressure of the CO gas during the sintering was controlled to be less than 80 Pa at the normal temperature to 1700 o C and to be within the range of 300±50 Pa in the temperature range higher than 1700 o C by properly adjusting the flow of the argon gas. The obtained sintered body was of a density of 2.05 g/cm³ and an open porosity of 36% by volume. Its crystal structure was observed with a scanning type electronic microscope to have a three-dimensional network structure in which silicon carbide crystals of an average aspect ratio of 2.5 were complicatedly entangled in many directions. The linear shrinkage for the produced molding was within a range of 0.25±0.02%. The sintered body was of a dimension precision within ±0.05 mm and of an average bending strength showing a very high value of 18.5 kg/mm². This sintered body was made to be in the form of a ring of an outside diameter of 30 mm, inside diameter of 15 mm and thickness of 5 mm. When dry sliding of this compound on a stainless steel (SUS304) was tested under an end surface load of 0.98 MPa (10 kg/cm²) by a ring-on-ring method at a sliding velocity of 500 mm/sec, the friction coefficient was 0.5 to 0.7 and the wear coefficient was 2.3 X 10⁻¹ mm/km (kg/cm²). Example 1: The same porous sintered silicon carbide body as in Control 1 was impregnated with perfluoropolyether under a vacuum. The rate of the open pores occupied by the perfluoropolyether with which this porous sintered silicon carbide body was impregnated was 90% by volume. When the dry sliding of the ceramic compound impregnated with this perfluoropolyether on a stainless steel (SUS304) was tested by the same method as in Control 1, the friction coefficient was 0.05 to 0.10 and the wear coefficient was 2.1 X 10⁻⁴ mm/km (kg/cm²). It was recognized to have a very high sliding characteristic. Example 2: In the same as in Example 1, the porous sintered silicon carbide body was impregnated with methylphenyl silicone in place of the perfluoropolyether. The rate of the open pores occupied by the methylphenyl silicone with which this porous sintered silicon carbide was impregnated was about 90% by volume. When the sliding characteristic of this ceramic compound was measured by the same method as in Example 1, the friction coefficient was 0.15 to 0.25 and the wear coefficient was 4.7 X 10⁻⁴ mm/km (kg/cm²). It was recognized to have a wear resistance about 490 times as high as in the above mentioned Control 1. Example 3: In the same as in Example 1, the porous body was impregnated with each of fluoroethylene, fluoroester, fluorotriazine, fluorosilicone, methylsilicone and fluoropropylmethylsilicone. The porous body impregnated with any of the above mentioned lubricants was recognized to have a high sliding characteristic. The following is to explain the case of firing each sintered body by using another ceramic material than silicon carbide. As detailed above, according to the present invention, there can be provided a valve characterized in that the sliding contact surface part of at least either of the fixed valve body 13 and movable valve body 14 is formed of a porous sintered ceramic body having open pores of a three-dimensional network structure and is charged with a liquid lubricant in the above mentioned pores so that thereby, even when the fixed valve body 13 and movable valve body 14 are always in sliding contact with each other, the connecting and disconnecting operation will be able to be made always lightly and stably with the operating lever. In the thus formed valve, not only the operation by the operating lever can be made lightly over a long period but also the fixed valve body and movable valve body 14 can be maintained in close sliding contact with each other to prevent the fluid from leaking out. Needless to say, the above is the same even with a valve of any form made to connect and disconnect the passage of such other fluid than cold water and hot water as, for example, such fluid as such liquid as, for example, oil or such gas as propane gas. Also, even in the case of an embodiment in which not only the sliding contact surface part of the fixed valve body 13 or movable valve body 14 is formed as described above but also the entirety of the fixed valve body 13 or movable valve body 14 is formed as mentioned above, the same effect will be able to be obtained. NUMERAL REFERENCE 10 a mixing plug, 11 a main valve body, 12 a supporting member, 13 a fixed valve body, 13a a passage, 14 a movable valve body, 14a a passage, 14b a recess, 15 a connecting member, 16 an actuating lever, 17 an operating lever, 18 a faucet, 20 a single water plug, 21 a primary side passage, 22 a secondary side passage, 23 a partition wall, 24 a main valve body.

Claims: A valve provided with valve bodies comprising: a fixed valve body, made of ceramics, constituting a part of a fluid passage between an inlet source and an outlet source; and a movable valve body, made of ceramics, in slidable face-to-face sealing contact with said fixed valve body for connecting and disconnecting said fluid passage between said inlet source and said outlet source whilst maintaining said face-to-face sealing contacting condition, wherein at least one of said fixed valve body and said movable valve body is composed of sintered silicon carbide ceramics body having three-dimensional open pores filled with liquid lubricant oil; said impregnated ceramics body presenting a sliding contact surface formed of both said liquid lubricant oil and said ceramics; said open pores is 5 to 40% by volume. A valve provided with valve bodies according to Claim 1 wherein said liquid lubricant oil is one or a mixture of more selected from among fluoroethylene, fluoroester, fluorotriazine, perfluoropolyether, fluorosilicon, their derivatives and their polymers. A valve provided with valve bodies according to Claim 1 wherein said liquid lubricant oil is one or a mixture of more selected from among methyl silicon, methylphenyl silicon, their derivatives and their polymers. A valve provided with valve bodies according to Claim 1 wherein the average granule diameter of the crystals of said sintered silicon carbide is less than 10 µm. A valve provided with valve bodies according to Claim 1 wherein said liquid lubricant oil is impregnated within said open pores at the rate of 100 parts by volume of the open pores of said sintered silicon carbide with at least 10 parts volume of said liquid lubricant oil.

Inventors: KITAMURA, KAZUHIRO, TSUKADA, KIYOTAKA 34, TATSUNOKUCHICHO 2-CHOME
Applicants: IBIDEN CO., LTD., KVK CO., LTD.
Application year: 1986
Main classification: C04B41
IPC codes: F16K3, C04B41, F16K11, C04B38, C04B35