WO1988009896A1

WO1988009896A1 - Friction rotary joint for hydraulic system components

Info

Publication number: WO1988009896A1
Application number: PCT/US1988/002005
Authority: WO
Inventors: Alfons Knapp
Original assignee: Masco Corporation
Priority date: 1987-06-10
Filing date: 1988-06-10
Publication date: 1988-12-15
Also published as: FR2635847A1; FR2635847B1; IT1211164B; IT8767500A0

Abstract

A friction rotary joint, particularly appropriate for hydraulic system components, made up of a tubular first component (11), a second tubular component (14) radially connected with the first tubular part, a seal (17) placed between the two tubular parts, at least one frusto-conical surface (12) formed in the first tubular component, a friction element (18) connected angularly with the second tubular part and presenting at least one frusto-conical surface (19) complementary to the frusto-conical surface (12) formed within the first tubular part and put into contact with it. An elastic ring (24) applies a direct elastic force between the two parts in such a way as to apply a contact pressure between the two complementary frusto-conical surfaces.

Description

FRICTION ROTARY JOINT FOR HYDRAULIC SYSTEM COMPONENTS

Technical Field The present invention refers to a friction rotary joint particularly adapted for hydraulic system components. The joint has applications for hydraulic components, particularly for faucets with a tube having adjustable position. The joint also addresses the requirement of joining a mobile part, such as a tube of adjustable position, the arm of a shower unit and so on to a fixed section, such as a faucet unit. The mobile part should be able to rotate at least within certain limits with respect to the fixed part. A controlled friction exists between the fixed part and mobile part in such a manner that handling is not impaired but the mobile part is stabilized to its assigned position. The necessary mobility between the parts is obtained by an opposing component, but must include the means to generate an adequate friction.

Background of the Invention

Up to now, friction in a component has been obtained by making a ring shaped surface in the mobile part act frontally against a corresponding surface of the fixed part, while these surfaces are pushed against each other by the force of a spring. Considering the need to leave the passages sufficiently free for the flow of liquid, this method is still not satisfactory because the ring shaped surfaces needed to generate the friction must have a greatly reduced area of contact and an appropriately sized spring cannot generate enough force. The reduced radius makes it necessary to have an elevated contact pressure to generate enough friction to the couple. Further, this elevated pressure, combined with the small area of the ring shaped surfaces, brings an early deterioration of these surfaces.

On the other hand, the spring, due to its small size, does not maintain the necessary high pressure as the annular surfaces deteriorate. It permits the joints to experience a rapid reduction of friction with time. This reduction must be offset initially with an excessive level of friction, which nevertheless becomes quickly insufficient. Other than this, the parts in the joints noted are only held together by a screw, and the generated friction transfers a moment, frequently causing the screw to unscrew.

What is needed is a joint of the type indicated, where it is possible to easily obtain, with economical and sure methods, a friction couple adequate to the demands, and furthermore, a couple that maintains its - character essentially unchanged, even after long periods of operation.

Summary of the Invention

According to one aspect of the invention,- a joint includes a first tubular part and a second tubular part connected with said first tubular part and able to rotate. A seal is held between the two tubular parts. At least one frusto-conical surface is formed in said first tubular part with a friction element angularly placed adjacent said second tubular part and presenting at least one complementary frusto-conical surface against the frusto-conical surface formed in the first tubular part and in contact with it. A direct elastic force is applied in such a way as to apply a pressure of contact between said complementary frusto-conical surfaces.

The friction which stops the movement of the joints is generated from the wedging between at least two frusto-conical surfaces, and therefore is greater than that which would be obtained from elastic forces applied if the surfaces generating the friction are straight such as found in the prior art noted before.

The conic nature of the surfaces causes a relatively high friction force while applying a relatively weak axial force. This arrangement easily surmounts the problems relative to generating the elastic force, which does not even require the use of a spring. An element of elastic material is sufficient to the scope of use. Because the complementary surfaces which generate friction are of conic nature, this presents a relatively large area with respect to their axial obstruction, and therefore gives way to limited wear and particular coupling stability. On the other hand, one of the frusto-conical surfaces can be made of an appropriate material, capable of causing an elevated coefficient of friction and negligible wear. These factors permit a joint, of relatively simple and economic structure, to have at the same time a reduced obstruction and the capacity to generate an elevated couple of friction destined to remain substantially unchanged over time.

Desirably, there are two frusto-conical complementary surface couples, having oppositely placed conicality, and said means for applying an elastic working force between two friction elements, each with frusto-conical surfaces. In this manner, the elastic force and operating forces to move the faucet spout operate only on parts intended to generate the couple of friction.

Brief Description of the Drawings Reference now will be made to the accompanying drawings in which:

Figure 1 illustrates on a small scale a perspective view of a faucet which has a rotatable joint to which the invention can be applied;

Figure 2 is an enlarged cross-sectional view along a longitudinal section of a joint according to a first embodiment of the invention;

Figure 3 is a cross-sectional view taken along line

III-III of Figure 2; and

Figure 4 is a view similar to that of Figure 2 showing a second embodiment of the invention. Detailed Description of the Preferred Embodiments The faucet illustrated in Fig. 1 is a single handle mixing faucet with a spout of changeable position. The faucet has a valve unit 1 from whose upper surface 2 emerges a control lever 3. A conduit 4 extends laterally from unit 1. A spout is in the form of a C and presents a central portion 6, a lower short arm 5 connected to the conduit 4 of the faucet, and an upper arm 7 of greater length than the lower arm 5, to which is connected a distribution head 9 with outlet opening 10. The head 9 is mounted on the upper arm 7 in such a way that it is able to rotate around an axis -d-. The lower arm 5 of the spout is connected to the conduit 4 of the faucet in such a way as to rotate around a substantially horizontal axis -b-. The connection between arm 5 and conduit 4 should provide sufficient friction to enable the spout to stay in the position in which it has been placed by the user, without being moved by its own weight and/or by the reaction to the fluid flux therein. the joint between the conduit 4 and the body 1 and arm 5, rotating around the axis -b-, represents, therefore, a typical example of a connection to which the invention can be applied.

In the form represented in Figs. 2 and 3, the joints according to the invention are made up of a tubular fixed part 11 to which a movable tubular part 14 is connected and able to rotate. An O-ring element 17 seals the two reciprocally mobile parts. Referring to Fig. 1, the fixed part 11 corresponds to the conduit 4 placed operatively on the body 1, while the mobile part 14 corresponds to the end of the lower arm 5 of the supply tube. For practical reasons of description, the part 11 is defined as fixed and part 14 as mobile. The functions of both parts, however, can be reversed, and as such, part 14 can be fixed and part 11 can be mobile. In special cases, both parts can be mobile.

In the form described here, the fixed part 11 provides an internal frusto-conical surface 12 and a supporting surface 13. For its part, the mobile part 14 presents a spline stem 15 and a threaded stem 16. On the spline stem 15 a friction element 18 is inserted which has a frusto-conical surface 19 complementary to the frusto-conical surface 12 of the fixed part 11 and is placed in contact with it. The element of friction 18 can move axially with respect to the mobile part 14, in order to be inserted, and is fixed against it when it is completely inserted. The element of friction 18 is fixed with respect to the mobile part 14 with respect to the rotation. A washer 23 is inserted on the mobile part 14 and is supported against the supporting surface 13 of the fixed part 11. A threaded ferrule (metal cap) 22 is screwed and locked on the threaded stem 16 of the mobile part 14, and maintains compression against the washer 23 and an elastic ring 24 made up of rubber or a similar material.

The elastic ring 24 compressed in this manner applies an elastic force to the ferrule 22 which, across the threaded stem 16, transmits to the mobile part 14. From this the element of friction 18 applies to the washer 23 an elastic force which, across the support 13, is transmitted to the fixed part 11. As a result of the application of this force, the frusto-conical surface 19 of the element of friction 18 is held and rotated against the frusto-conical surface 12 of the fixed part 11. Between these two surfaces, friction is generated which depends on the elastic force applied and the total area provided by the conicality of the surfaces 12 and 19. If the frusto-conical surfaces 12 and 19 are slightly inclined with respect to the axis of connection, as in the example illustrated, the couple of friction produced in this manner is relatively elevated with respect to the force exerted by the elastic ring 24. Furthermore, the element of friction 18 can be realized in a suitable material, such as a plastic material, a plastic material strengthened with fiberglass, a ceramic or other appropriate material, in such a way as to give an elevated coefficient of friction and also a negligible wear of the cooperating surfaces.

In the representation according to Fig. 2, the friction between the support 13 and the washer is not, ^'on the other hand, very elevated because the axial force applied on the elastic element 24 is relatively weak, and because those parts are not subject to appreciable wear. Preferably, as illustrated, the washer 23 is also engaged to the spline stem 15 of the mobile part 14, in such a way as to be unable to rotate so that the ferrule 22 has no moment of force exerted thereon. Even in -the absence of this provision, the screwed ferrule 22 would therefore be less susceptible to unscrewing or loosening.

Naturally, the spline stem 15 could be, if desired, substituted with any other form of movable but not rotatable insert, for example of a polygonal shape, a coupling with a key, etc. The elastic element 24, as said before, can be a simple ring made of rubber or similar material, but naturally could also consist of a cup spring or another equivalent elastic part.

In the embodiment shown in Fig. 4, the fixed part 31 presents a first frusto-conical internal surface 32 and a second frusto-conical internal surface 33, whose conicality is oppositely placed with respect to the first. The two bases of smaller diameter of the frusto-conical surfaces 32 and 33 oppose each other. For its part, the mobile part 34 is substantially identical to that according to Fig. 2 and, as such, possess a provision of seal 37 and presents a spline stem 35 and a threaded stem 36. On the spline stem 35, in this case, two elements of friction 38 and 40 are inserted, each one of which possesses a frusto-conical surface 39 and 41, respectively. Surface 39 is complementary to the frusto-conical surface 32 of the fixed part 31 and placed in contact with it. Surface 41 is complementary to the frusto-conical surface 33 of the fixed part 31 and placed in contact with it.

Each of the elements of friction 38 and 40 are axially movable with respect to the mobile part 34 in order to be inserted. But the first friction element 38, when completely inserted, rests against the mobile part 34, while the second friction element 40 stays permanently movable on the spline stem 35. A washer 43 (which in this case has no motive to be engaged to the spline stem 35) is inserted on the mobile part 34 and is supported against the second friction element 40. A threaded ferrule 42 is screwed and blocked on the threaded base 36 of the mobile part 34, and maintains a ring of elastic material 44 (of rubber or other similar material) compressed against the washer 43.

With this construction, the compressed elastic ring 44 applies an elastic force to the ferrule 42 which is transmitted to the mobile part 34 and from this to the first element of friction 38. The elastic ring 44 also applies an elastic force to the washer 43 which is transmitted to the second element of friction 40. Through the coupling between the frusto-conical surfaces, two equal and opposite forces are therefore applied to fixed part 31. Because of the application of thes.e forces, the frusto-conical surfaces 39 of the first element of friction 38 is pushed against the frusto-conical surfaces 32 of the fixed part, while the frusto-conical surfaces 41 of the second element of friction 40 is held fast against the frusto-conical surface 33 of the fixed part 31. Between these frusto-conical surfaces a friction is generated which depends on the elastic force applied and on the conicality of the surfaces, and which, upon all other conditions being equal, is even greater than in the embodiment shown in Fig. 2.

Furthermore, in this case, every transmission of force that does not pass through the friction elements 38 and 40 is avoided, while in the previous embodiment force of contact under pressure between the washer 23 and the supporting surface 13. Because of this, the second embodiment according to Fig. 4, represents the total application of the concept of the invention, which is likewise susceptible to a partial application in the sense indicated by the embodiment shown in Fig. 2.

Naturally, in the form according to Fig. 4, the same considerations are valid, relative to possible modifications, specifically stated for the embodiment shown in Fig. 2. Also, it should be noted that, considering the indicated disposition of the frusto-conical surfaces, with the bases of less diameters opposing each other, which in general is found to be more desirable, the same surfaces can be used with the larger bases opposing each other. In that case the friction elements 38 and 40 could be constructed of more separate parts, or otherwise left retracted until they can be inserted in the device. Alternately, the friction elements can be applied onto fixed member 31 and the elastic force can be achieved by an elastic ring screwed into the open end of member 31. Rotatable member 34 can then have integral frusto-conical surfaces.

The invention provides articulations of hydraulic force of simple and economical structure. Having reduced the obstruction and increased axial space of passage for the flow of liquid, the degree of friction can be preset with precision and remains unchanged even after long period of use.

Variations and modifications of the present invention are possible without departing from the scope and spirit as defined in the appended claims.

Claims

I claim:

1. A friction rotary joint, particularly adapted for elements of hydraulic systems, characterized by a first tubular part, a second tubular part radially connected to the said first tubular part, a seal placed between the two tubular parts, at least one frusto-conical surface formed in said first tubular part, a friction element rotatably fixed with said second tubular part and presenting at least one frusto-conical surface complementary to the frusto-conical surface formed in the first tubular part and put into contact with it, and means for applying a contact pressure between said frusto-conical complementary surfaces.

2. A friction rotary joint according to claim 1 further characterized by the fact that said element of friction is made of a material presenting an elevated coefficient of friction and low wear, like a plastic material, a plastic material reinforced with fiberglass, a ceramic or similar material.

3. A friction rotary joint according to claim 1 further characterized by said element of friction is rotatably fixed with respect to said second tubular part by a spline connection therebetween.

4. A friction rotary joint according to claim 1 further characterized by said means for applying a contact pressure including a ring of elastic material such as rubber or similar material.

5. A friction rotary joint according to claim 1 further characterized by said means for applying a contact pressure including a cup washer or similar elastic element.

6. A friction rotary joint according to claim 1 further characterized by two pairs of frusto-conical complementary surface.s having their conicality oriented in opposite directions, and said means for applying a contact pressure being transmitted through two elements of friction, each presenting a frusto-conical surface.