SEAL ASSEMBLIES

Abstract: A seal assembly particularly suited for use in arduous operating conditions, for example, those encountered in car engines. The seal assembly comprising a sealing member (2) which includes a seal mountable for sealing engagement with respect to a rotatable shaft (9), and a stiffening ring (5) having the seal (3) secured thereto. The stiffening ring (5) is formed with an arm member formed so that in operation a section (19) of the arm member (17) engages in means provided in the bearing assembly (10) so that the bearing assembly (10) and the shaft (9) form part of the seal assembly so as to provide a unitised bearing and seal assembly.

Description: SEAL ASSEMBLIES This invention relates to seal assemblies, and in particular unitised bearing and seal assemblies for use with fluid pumps, for example, water pumps. Conventional sealing arrangements for use with water pumps consist of a large number of component parts assembled into an assembly unit. Although the seals themselves are relatively small, the large number of component parts in the assembly means that a large assembly space is required. This in turn, means that in addition to being complex in assembly the sealing arrangements are bulky and expensive. Further, conventional sealing arrangements require precise axial location with respect to a shaft, in order to ensure that adequate sealing therebetween results. The actual assembly of the sealing arrangement onto the shaft, for example of a water pump, can itself result in damage to the surface of the shaft. Any damage so caused may provide a leakage path around the sealing arrangement, so destroying the integrity of the sealing arrangement. The present invention is concerned with providing a unitised seal assembly in which the above problems are overcome or in the very least drastically reduced. In accordance with the present invention a seal assembly comprises a sealing member which includes: a seal mountable for sealing engagement with respect to a rotatable shaft; and - a stiffening ring having the seal secured thereto; wherein the stiffening ring has an arm member formed so that in operation a section of the arm member engages in means provided in the bearing assembly so that the bearing assembly and the shaft form part of the seal assembly so as to provide a unitised bearing and seal assembly. A seal assembly made in accordance with the present invention includes the following beneficial features: a) It is more compact in design. This results from the reduction in size of the space envelope required for the seal. b) It is more simply assembled and mounted on the shaft. There is no critical operational setting required to ensure sealing integrity. and c) The load which has to be applied to ensure adequate sealing is greatly reduced. Thereby reducing the chance of damage to the surface of the shaft during mounting of the seal assembly. Further, resultant from the above a seal assembly which in addition to its compact design characteristics, is relatively cheap to produce, and is simple to assemble, is provided. Preferably, the seal is a PTFE seal and, most preferably, a PTFE lined seal. In the case of a PTFE lined seal, preferably, the PTFE is bonded to a base elastomer/rubber. This bonding may be achieved by moulding the base elastomer/rubber and PTFE liner in a single moulding operation. The seal can include/utilise any type of sealing and/or principle. In a preferred embodiment of the invention the seal is a lip seal, and most preferably a composite elastomeric lip seal. Seal assemblies formed in accordance with the present invention have the further advantage over the known embodiments in that they are suited for operation in the very arduous operating conditions which arise from the increasing car engine performance requirements imposes thereupon, for example, in the water pump. That is to say they are ideally suited for operation -under conditions which will place heavy stresses thereupon i.e. at about 120 C and 1 atm. with speeds in excess of 6000 r.p.m., under which conditions experimental trials have shown that seal assemblies in accordance with the present invention have an operating life in excess of 1600 hours. Further, the above conditions are those which are typically experienced and which cause conventional seal arrangements to breakdown, and thereby provide inadequate sealing, well within this period. In the case where an additional force is required to achieve sufficient sealing between the sealing member and the rotatable shaft, the seal assembly preferably also comprises a garter spring. Under certain operating conditions the garter spring will be subjected to a corrosive environment, in this case preferably, the garter spring is corrosive resistant with regard to the environment prevailing in the vicinity thereof. In one embodiment of the invention it is envisaged that the sealing assembly will be used in a water pump. Therefore, in this case the corrosive resistant material will be stainless steel. The actual positioning of the garter spring relative to the sealing surface of the seal is dictated by the type/function of the sealing principle involved. The basic logistics involved in determining the position of the garter spring are well known and appreciated in the industry. Therefore no detailed explanation as to these will be provided. The sealing member may incorporate a flinger assembly, preferably, the seal and flinger assembly are formed so that the inner extent of the flinger is in close proximity to the inner extent of the seal. Alternatively, a retention bead is moulded into or onto the seal. This allows the flinger to be retained in the free condition at the outer perimeter of the flinger. The stiffening ring may be made from a suitable thermoplastic material. However, preferably, the stiffening ring is a metal stiffening ring, and most preferably, a corrosive treated metal stiffening ring. Preferably, the sealing member is secured to the outer race assembly of the bearing assembly of the shaft by means of the arm on the stiffening ring. Preferably, the arm on the stiffening ring engages in a recessed groove provided in the bearing assembly. Preferably, the recessed groove and the arm are provided with complimentary shaped interacting sections. The provision of complimentary shaped interacting sections means that the locational efficiency of the mounting of the sealing member with respect to the bearing assembly is improved, i.e. the bearing assembly and the sealing member do not rotate significantly with respect to each other. In order to improve the operational characteristics of the seal assembly, preferably, the shaft about which in operation the sealing member is assembled in the vicinity of the seal assembly is hardened to improve the seals/shafts relative running performance. Preferably, the shaft is inductively hardened. Inductive hardening in certain materials may have beneficial effects on the corrosion characteristics thereof, i.e. improve corrosion resistant properties. This invention also includes a sealing member for use in a seal assembly made in accordance with the present invention. The ' invention will now be illustrated, by way of description of two examples of the invention as detailed in the accompanying drawing in which: Figure 1 shows a diagrammatic illustration of a seal assembly made in accordance with the present invention and mounted in a pump body; and Figure 2 shows a diagrammatic illustration of a second seal assembly made in accordance with the present invention and mounted in a pump body. With reference to Figure 1, a bearing and seal assembly mounted in a water pump 1 comprises a sealing member 2 which includes: a base elastomeric seal member 3; - a PTFE seal member 4 bonded to the base elastomeric seal member 3; a stiffening ring 5 to which the base elastomeric seal member 3 is adhered; and - a stainless steel garter spring 6. The water pump 1 comprises: - a body 7 having a water condensate drain 8; and - a rotatable shaft 9 having a bearing assembly 10. The rotatable shaft 9 is inductively hardened in the vicinity of the contact between the seal member 3 and shaft 9. The bearing assembly 10 includes: an inner race assembly 11 which is formed as a groove in the shaft 9? an outer race assembly 12 secured to the pump 1 and having a co-operating groove 13; and - a number of ball bearing members 14 mounted between the grooves in the inner and outer race assemblies 11, 12. A dust cover 15 is mounted in a groove 16 in the outer race assembly so as to prevent ingress of dust/dirt and any extraneous matter into the bearing assembly 10. The stiffening ring 5 of the sealing member 2 is made from metal, and includes: an arm member 17, having an orifice 18 which when the sealing member 2 is mounted with respect to the shaft 9 co-operates with the water condensate drain 8 and a lip securing section 19; and - a shaped section 20. The base elastomeric seal member 3 is moulded to the shaped section 20 of the stiffening ring 5, and includes: a web section 21 which extends along a portion of the arm member 17 and is formed with a corrugated profile; and - an arm section 22 which is shaped so that the PTFE seal member 4 which is bonded thereto can form a sealing lip contact 23 with the shaft 9 when mounted thereabouts. The garter spring 6 is mounted so that it acts against the arm section 22 in a position which will enhance the sealing efficiency of the sealing lip contact 23. When the sealing member is mounted in the bearing, the lip securing section 19 of the stiffening ring 5 engages in a recess 24 formed in the outer race assembly 12 and is coined thereto in order to achieve a secure mounting. Further the web section 21 of the base elastomeric seal member 3 provides a st tic sealing contact with the pump body 1. No referring to Figure 2 of the drawings, a second seal assembly made in accordance with the present invention is very similar to the assembly shown in Figure 1 and like numerals have been used to show like components. The only difference between the two embodiments resides in the fact a bearing sleeve arrangement 25 is provided around the rotatable shaft 9. The bearing sleeve arrangement 25 comprises a metal insert 26 about which an elastomeric coating 27 is moulded. The elastomeric coating 27 has a bearing surface 29 of corrugated structure. The metal insert 26 has an arm 28 of reduced thickness. The sealing member 2 is assembled onto the bearing assembly 10 in an identical fashion to that shown with the seal assembly in Figure 1. The bearing surface arrangement 25 is mounted around a rotatable shaft 9 so that arm 28 is in close proximity to stiffening ring 5 of the sealing member 2, and surfaces 29 is in contact with the shaft. This means the PTFE liner 4 of the sealing member 2 engages with the metal insert to 26 of the bearing sleeve arrangement 25 so as to form a sealing lip contact 23. In operation the bearing surface 25 rotates with the shaft. The physical operation of the seal is very similar to that of conventional radial lip-type seals and hydrodynamic features may be incorporated. The primary importance of the seal relates to the compact and simple nature thereof.

Claims: CLAIMS 1. A seal assembly comprises a sealing member which includes: a seal mountable for sealing engagement with respect to a rotatable shaft; and - a stiffening ring having the seal secured thereto; wherein the stiffening ring has an arm member formed so that in operation a section of the arm member engages in means provided in the bearing assembly so that the bearing assembly and the shaft form part of the seal assembly so as to provide a unitised bearing and seal assembly. 2. A seal assembly as claimed in claim 1, in which the seal is a PTFE seal. 3. A seal assembly as claimed in claim 1, in which the seal is a PTFE lined seal. 4. A seal assembly as claimed in claim 3, in which the PTFE is bonded to a base elastomer. 5. A seal assembly as claimed in claim 3, in which the PTFE is bonded to a base rubber. 6. A seal assembly as claimed in claim 3, in which the PTFE is bonded to a base material in a single moulding operation. 7. A seal assembly as claimed in any one of the previous claims, in which the seal is a lip seal. 8. A seal assembly as claimed in claim 7, in which the seal is a composite lip seal. 9. A seal assembly as claimed in any one of the preceding claims, which further comprises a garter spring. 10. A seal assembly as claimed in claim 9, in which the garter spring is made from stainless steel. 11. A seal assembly as claimed in any one of the preceding claims, in which the seal includes a flinger assembly formed so that the inner extent of the flinger is in close proximity to the inner extent of the seal. 12. A seal assembly as claimed in any one of the preceding claims, in which the stiffening ring is made from metal. 13. A seal assembly as claimed in any one of claims 1 to 11, in which the stiffening ring is made from a thermoplastic material. 14. A seal assembly as claimed in any one of claims 1 to 11, in which the stiffening ring is made from corrosively treated metal. 15. A seal assembly as claimed in any one of the preceding claims, in which the arm on the stiffening ring engages in a recessed groove provided in the bearing assembly. 16. A seal assembly as claimed in claim 15, in which the recessed groove and the arm are provided with complimentary shaped interacting sections.

Inventors: GREGORY CHRISTOPHER, GREGORY, CHRISTOPHER
Applicants: WOODVILLE POLYMER ENG, WOODVILLE POLYMER ENGINEERING LIMITED
Application year: 1989
Main classification: F16J15
IPC codes: F16C33, F16J15