JOINT FOR A HOSE OR TUBE

Abstract: A joint for coupling a hose or tube through which a high pressure fluid is transmitted, which has a main body with a fastening portion whose end surface is tapered, a socket having therein an accommodating space with a tapered surface for accommodating at least one shrinkable press ring and an insert cylinder inserted into the hose or tube, the press ring being shrunk when the socket is rotated to decrease the distance between the two tapered surfaces of the socket and the fastening portion.

Description: BACKGROUND OF THE INVENTION This invention relates to a joint for coupling a hose or tube with a transmission line for a high pressure fluid such as oil or water. As one of this kind of joints, YOKOHAMA AEROQUIP CO., LTD. in Japan is now manufacturing a joint comprising a main body (nipple) and a socket cooperating with the main body. The main body has a connecting portion to be connected to an inlet or outlet of a pressure fluid in a machine on its one side, a cylindrical insert portion to be inserted into a hose or tube and a hexagonal nut portion, provided between the connecting portion and the cylindrical insert portion, with which a spanner engages for rotating the main body. The cylindrical insert portion has a screw, at its root portion, to be meshed with a screw formed at the base portion of the socket and the outer peripheral surface of the cylindrical insert portion is tapered toward the front end thereof. The hose or tube is fastened between the inner surface of the socket with the female screw and the outer tapered surface of the cylindrical insert portion of the main body. In this conventional joint, first, the end portion of a hose or tube is inserted while being rotated into the socket which is fastened by a vice. Then, the socket with the hose or tube is fastened again by the vice in a position where the cylindrical insert portion of the main body can be easily inserted into the socket and an assembly mandrel is inserted into a through hole, formed in the main body, through which the pressure fluid passes. Thereafter, the cylindrical insert portion of the main body with the assembly mandrel is inserted while being rotated into the hose or tube held in the socket in a manner that a spanner is engaged with the hexagonal nut portion of the main body. After the side surface of the hexagonal portion abuts against the end surface of the socket, the assembly mandrel is drawn from the through hole of the main body. In this manner, the above conventional joint requires not only some troublesome steps for fastening the hose or tube between the socket and the main body but also the assembly mandrel as a fastening tool. In addition, as the hose or tube is screwed into the socket, the outer circumferential surface of the hose or tube is injured to have a bad effect upon endurance against pressure. Further, when the hose or tube is connected to the above conventional joint, the vice and the assembly mandrel are required. Accordingly, the hose or tube cannot be directly connected to the main body in a state wherein the main body is fastened on a machine. SUMMARY OF THE INVENTION It is an object of this invention to provide a joint which neither need a vice and an assembly mandrel nor any troublesome steps when a hose or tube is fastened. According to this invention, there is provided a joint for coupling a hose or tube with a transmission line for a high pressure fluid such as oil, water or gas, which comprises: a) a main body having a fastening portion whose outer peripheral surface is formed with a screw and whose end surface is tapered; b) a socket having a screw engaged with the screw of the main body at its one end and an accommodating space therein whose one end is formed with a tapered surface opposite to the tapered surface of the main body; c) an insert cylinder whose root portion is connected to the main body and which is inserted into the hose or tube; and d) shrinkable press means disposed in the accommodating space of the socket for fastening the hose or tube on the insert cylinder, the press means having two tapered surfaces one of which corresponds to the tapered surface of the socket and the other one of which corresponds to the tapered surface of the fastening portion of the main body, the press means being shrunk when the socket is rotated so as to decrease the distance between the two tapered surfaces of the fastening portion and the socket. The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. l is a side view, partly broken, of a joint according to this invention; FIG. 2 is an exploded view, partly broken, showing each element of the joint; FIG. 3 is a sectional view showing a state wherein the rearmost press ring is engaged with a rear annular recess of a socket; FIG. 4 is a front elevational view, partly broken, showing a state wherein the rearmost press ring is expanded with an expansion tool to be received in the rear annular recess; FIG. 5 is a side view, partly broken, showing a state wherein the joint is fastened; FIG. 6 is a front elevational view of a press ring; FIG. 7 is a side view, partly broken, of another embodiment of the joint; FIG. 8 is a side view, partly broken, of still another embodiment of the joint; FIG. 9 is a side view, partly broken, of a further embodiment of the joint; FIG. l0 is a side view of a press sleeve shown in FIG. 9; FIGS. ll and l2 are side views of other embodiments of a press sleeve, respectively; and FIG.l3 is a side view, partly broken, of a conventional joint. DETAILED DESCRIPTION OF THE INVENTION As conducive to a full understanding of the nature and utility of the present invention, a brief consideration of a typical conventional joint will be first presented below with reference to FIG. l3. The conventional joint comprises a main body (nipple) l00 and a socket l0l cooperating with the main body l00. The main body l00 has a connecting screw portion l02 which is connected to an inlet or outlet of a pressure fluid in a machine on its one side, a cylindrical insert portion l03 which is inserted into a hose or tube l05 to be fastened on the other side and a hexagonal nut portion l04 which is provided between the screw connecting portion l02 and the cylindrical insert portion l03. The cylindrical insert portion l03 is tapered to be smoothly inserted into the hose or tube l05. Further, the cylindrical insert portion l03 has a screw portion l03a with which the root portion l0la of the socket is meshed. When the hose or tube is fastened on the cylindrical insert portion l03 of the main body l00, first, the hose or tube l05 is screwed into the socket l0l which is held by a vice. Then, the cylindrical insert portion l03 is inserted into the hose or tube l05 in such a manner that the main body l00 is rotated by a spanner holding the hexagonal nut portion l04 in a state wherein an assembly mandrel l06 is inserted into the inner space l07 of the main body l00. Accordingly, when the hose or tube is connected to the joint, the vice and the assembly mandrel are necessary. Further, the cylindrical insert portion l03 is inserted into the hose or tube l05 held by the socket l0l in a manner that the main body l00 is rotated. At this time, the socket l0l is held tightly by the vice. Therefore, the hose or tube l05 cannot be connected to the main body l04 in a state wherein the main body l04 is connected to a machine. FIGS. l to 5 show a first embodiment of this invention. In FIGS. l and 2, a joint according to this invention has a hollow main body l in which a through hole h is provided. The main body l is formed with a hexagonal nut portion la at the center portion of the body l in its axial direction. A fastening tool is engaged with the nut portion la when the joint is fastened. On one side of the portion la is provided a connecting portion 2 having a male screw which is engaged with, for example, an outlet 3 for pressure oil, of a machine while the other side of the portion la is provided with a fastening portion 4 having a male screw 4a at its outer peripheral surface. The distal end face of the fastening portion 4 forms an inclined or tapered surface 4b which is inclined toward the nut portion la. Inside of the fastening portion 4 are provided two middle and bottom recesses 4c and 4d in the form of steps and the bottom recess 4d supports fixedly the root portion of an insert cylinder 5. The root portion of the cylinder 5 is fixed to the bottom recess 4d by e.g. brazing or welding. The insert cylinder 5 has a plurality of projecting portions 5a, 5a, ..., 5a in the form of a wave in section at its outer peripheral surface at a predetermined space interval. The projecting portions 5a bite the inner surface of a hose or tube T to be connected with the joint thereby to prevent leakage of fluid or prevent the hose or tube from coming out from the joint. The projecting portions 5a may have other shapes. The insert cylinder 5 may be formed integrally with the fastening portion 4. The male screw 4a of the fastening portion 4 is screw-engaged with the female screw 6e formed at the root portion of a fastening socket 6. The fastening socket 6 has three inner front, middle and rear annular surfaces 6a, 6b and 6c in a step manner. The middle surface 6b defines an accommodating space 7 in which three press rings 8 and two spacer rings 9 are disposed alternately. At the border between the two adjacent surfaces 6a, 6b is formed an inclined annular surface 6d which is expanded toward the middle surface 6b from the front surface 6a. Further, on the opposite side of the annular surface 6d with respect to the middle surface 6b is provided the rear surface (recess) 6c whose diameter is slightly larger than that of the middle surface 6b. The rear surface 6c receives the rearmost press ring 8 expanding because of its elasticity when the fastening socket 6 is separated from the main body l thereby to prevent other press rings 8 and the spacer rings 9 from dropping out of the accommodating space 7. The press rings 8 have elasticity, respectively, and are apt to expand when an outer force is released. The joint is sold to users in a state wherein the socket 6 with the press and spacer rings 8, 9 therein is separated from the main body l. At this time, the rear press ring 8 is received in the rear recess 6c of the socket to function preventing the rings 8, 9 from dropping out of the socket 6 as shown in FIG. 3. If the press rings have no elasticity, a tool 20 having a guide body 2l and a conical surface 22 is inserted into the inside of the rings 8, 9 when the joint is assembled so that the rearmost press ring 8 is expanded to be received in the rear recess 6c, thereby to confine the other rings 8, 9 in the accommodating space 7 as shown in FIG.4. A coaxial annular tapered opening 6a at the front portion of the socket 6 through which the hose or tube extends outwardly is expanded gradually toward the front end of the joint thereby to absorb expansion of the hose or tube T at its corresponding portion Ta in both cases when the joint is fastened as shown in Fig. 5 and also the fluid pressure is applied, moreover, to absorb displacement occurred by the vibration and bending of the hose or tube during operation. Accordingly, the hose or tube is reliably prevented from being broken at the portion Ta in these cases. Each press ring 8 has a slot 8a for enabling the ring 8 to shrink inwardly. Further, each press ring 8 has a trapezoidal shape in cross section, with two tapered surfaces 8b, 8b, which are convergent in the radially outward direction and has an annular projection 8c on its inner surface for biting into the outer surface of the hose or tube T as shown in FIGS. 2 and 6. Each spacer ring 9 is located between the two adjoining press rings 8 and has an inverse trapezoidal shape, in cross section, provided with two inversely tapered surfaces 9a, 9a which are convergent in the radially inward direction and which are opposite to the tapered surfaces 8b, 8b, respectively. When the hose or tube T is fastened by this joint, first the socket 6 is connected to the main body l while engaging the female screw 6e of the socket 6 with the male screw 4a of the main body. At this time, the press and spacer rings 8, 9 have already been accommodated in the accommodating spacer 7 in a state wherein the forward tapered surface 8b of the front press ring 8 contacts the tapered surface 6d of the socket 6, the backward surface 8b of the rearmost press ring 8 contacts the corresponding tapered surface 4b of the main body l and each of the other tapered surfaces 8b of the press rings 8 contacts the corresponding inversely tapered surface 9a of each spacer ring 9. Thereafter the hose or tube T is inserted into a space defined by the inner surfaces of the press and spacer rings 8, 9 and the outer peripheral surface of the insert cylinder 5 until the distal end of the hose or tube T is accommodated in the middle recess 4c of the main body l as shown in FIG. l. As the socket 6 is rotated, the distance between the tapered surface 6d of the socket 6 and the inversely tapered surface 4b of the main body l gradually decreases so that each tapered surface 8b of the press ring 8 slides radially inwardly along each corresponding surface. Accordingly, the annular projection 8c of each press ring 8 bites into the outer peripheral surface of the hose or tube T while, at the same time, the projecting portions 5a of the insert cylinder 5 bite into the inner surface of the hose or tube T as shown in FIG. 5. In this manner, the hose or tube T is tightly fastened between the inner surfaces of the press and spacer rings 8, 9 and the outer surface of the insert cylinder 5. When the hose or tube T is released from the joint, the socket 6 is rotated in the inverse direction to expand each press ring 8 due to its own elasticity. Other embodiments of this invention will now be explained with respect to FIGS. 7 to l2. In FIG. 7, one spacer ring l0 which is wider than the spacer ring 9 in the first embodiment is used. The spacer ring l0 has two inclined surfaces l0a, l0a which cooperate with the corresponding inclined surfaces 8b, 8b of the two press rings 8 disposed on the opposite sides of the spacer ring l0, respectively. Further, in FIG. 8, one spacer ring 9 of the first embodiment is disposed between the two press rings 8, 8. In these two embodiments, as the number of the spacer rings is decreased as compared with the first embodiment, the force for fastening the hose or tube T is decreased. Therefore, these two embodiments are suitable for a joint for dealing with a medium or low hydraulic or fluid pressure, respectively. In FIG. 9, instead of the combination of the spacer rings and the press rings, a press sleeve ll is disposed in an accommodating space l2 defined by the fastening portion l3a of a main body l3, the inside of a socket l4 and the outer peripheral surface of the hose or tube T. The press sleeve ll is made of elastic material and is in the shape of a barrel. Further, the press sleeve ll has two inclined annular surfaces lla, llb on the opposite sides of a flat annular surface llc and a slot lld in its longitudinal direction by which the press sleeve ll is shrinkable. On the inner surface of the press sleeve ll are formed two annular recesses lle, lle so as to provide three annular projections llf, llf, llf for biting into the outer surface of the hose or tube T. When the hose or tube T is fastened, the inclined inner surface l4a of the socket l4 and the inclined surface l3b of the fastening portion l3a abut against the inclined annular surfaces lla, llb, respectively, thereby to cause the press sleeve ll to shrink inwardly whereby the annular projections llf bite into the hose or tube T. A slanting slot lle of the press sleeve ll can be substituted for the straight slot lld of the press sleeve ll as shown in FIG. ll. Further, the sleeve ll may have a slot llf in the shape of a continuous as shown in FIG. l2. In this invention, first, the socket 6 is engaged with the fastening portion 4 and thereafter the hose or tube T is inserted straight into a space between the inner surface of the socket and the outer peripheral surface of the insert cylinder without being rotated. Then, the socket 6 is rotated to shrink the press rings 8. Accordingly, a fastening step for the hose or tube T is very simple, nevertheless, a big force for fastening the hose or tube T is obtained. Furthermore, an assembly mandrel and a vice are not necessary for carrying out the fastening step. In addition, as the hose or tube T is inserted straight into the socket 6 without being rotated, the peripheral surface of the hose or tube T is not injured.

Claims: 1. A joint for coupling a hose or tube with a transmission line for a high pressure fluid such as oil, water or gas, which comprises: a) a main body having a fastening portion whose outer peripheral surface is formed with a screw and whose end surface is tapered; b) a socket having a screw engaged with the screw of the main body at its one end and an accommodating space therein whose one end is formed with a tapered surface opposite to the tapered surface of the main body; c) an insert cylinder whose root portion is connected to the main body and which is inserted into the hose or tube; d) shrinkable press means disposed in the accommodating space of the socket for fastening the hose or tube on the insert cylinder, the press means having two tapered surfaces one of which corresponds to the tapered surface of the socket and the other one of which corresponds to the tapered surface of the fastening portion of the main body, the press means being shrunk when the socket is rotated so as to decrease the distance between the two tapered surfaces of the fastening portion and the socket. 2. A joint according to claim l, wherein the shrinkable press means comprises a plurality of press rings and at least one spacer ring disposed between the two adjoining press rings, the press ring having a trapezoidal shape to form two tapered surfaces on its opposite sides in section and a slot for enabling it to shrink inwardly, the spacer ring having an inverted trapezoidal shape corresponding to that of the press ring. 3. A joint according to claim 2, wherein each of the press rings has an annular projection on its inner surface for biting into the hose or tube when the joint is fastened. 4. A joint according to claim l, wherein the shrinkable press means comprises a press cylinder in the shape of a barrel having two tapered surfaces corresponding to the two tapered surfaces of the fastening portion and the socket, respectively, and a slot for enabling it to shrink inwardly. 5. A joint according to claim l, wherein the insert cylinder has at least one projecting portion on its outer peripheral surface for biting into the inner surface of the hose or tube. 6. A joint according to claim 2, wherein the socket has an annular recess for receiving the rearmost press ring for preventing other press rings and the spacer ring from droping out of the socket. 7. A joint according to claim l, wherein the socket has a coaxial annular tapered opening through which the hose or tube extends outwardly at the front portion of the socket, the coaxial annular tapered opening being expanded gradually toward the front end of the socket to absorb expansion of the hose or tube in both cases when the joint is fastened and the fluid pressure is applied, moreover, to absorb displacement occurred by the vibration and bending of the hose or tube during operation, thereby preventing the hose or tube from being broken.

Inventors: TSUCHIYA, YOSHIKI IHARA KOATSU TSUGITE KOGYO K.K.
Applicants: IHARA KOATSU TSUGITE KOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: F16L33
IPC codes: F16L33, F16L19