Seal with support body for rotary valve shaft

Abstract

An asymmetrical annular sealing element (2) which is positively linked as a composite part to an annular support body (4) optionally made of plastic or metal and dynamically seals a shaft (1), characterized in that a static sealing lip (14) of the sealing element (2) is statically pressed and firmly chambered by the support body (4) and wherein a main sealing lip (11) with a secondary lip (15), which are connected to the static sealing lip (14) by a connecting web (12), bear against the shaft (1) in the dynamic sealing area and a tilting effect towards the shaft (1) is caused by a cavity (17) between the secondary lip (15) and a straight shoulder (7) of the support body (4) when pressure is applied.

Description

[0001] Summary: The invention relates to an asymmetric sealing element 2, which is positively connected to an annular support body 4 optionally made of plastic or metal as a composite part, is then statically inserted into a housing 3 of a coolant control module 3 and dynamically seals a rotary valve shaft.

[0002] After this assembly step, the shaft 1 or a tube can be inserted into the section of the composite seal, which can be dynamically or statically sealed radially.

[0003] The sealing element has a dynamically sealing main sealing lip on the media side and a secondary lip that protects against the atmosphere, which can serve as a vacuum-tight lip during negative pressure filling or as a lubrication chamber and protection against external influences.

[0004] A further sealing lip 14 is statically pressed firmly between the support body 4 and the housing 3.

[0005] The support body 4 forms the stable base for the sealing element 2 and has a wedge-shaped contour on the outside. This has the task of permanently chambering the outer statically pressed sealing lip 14 via positive locking after assembly. Furthermore, the support body 4 can also be used simultaneously as a plain bearing and guide element for the shaft 1 to center the shaft 1 or to protect the sealing element 2 against eccentric angular deflection of the shaft 1 or to act as a protective body for the sealing element towards the atmospheric side. A further task of the support ring 4 is to protect the sealing lip from turning inside out during the assembly process when the shaft 1 is inserted, as a pre-centering process takes place.

[0006] The support body is recessed in the area of ​​the secondary sealing lip and provides a beneficial tilting effect as well as free inward movement of the main sealing lip connection to the sealing shaft 1. The support body 4 forms a pivot point in the axial direction, on which the sealing body rests and, when pressurized, can tilt inward in an angular movement toward the shaft to be sealed, thereby increasing the sealing effect of the main sealing lip.

[0007] The outer sealing lip 14 can be designed in two different axial directions to the medium space or to the atmosphere and is aligned according to the given mounting direction in the housing 3. Description:

[0008] The invention relates to a shaft seal that seals a static or moving shaft against overpressure and underpressure, both in rotation and translation. This can be used, for example, in a cooling water control module in a vehicle and has the following features: - A housing with a defined cylindrical sealing seat; - a sealing element which can be linked to a support body, in particular a support ring; - a support body, in particular a support ring, which connects the sealing element in a wedge-shaped and form-fitting manner; - a rotary valve shaft that is dynamically sealed in the housing.

[0009] Such seals are already familiar in automotive engineering. They typically feature pure elastomer lip seals, double groove seals, or metal composite seals with a worm spring and vulcanized stiffening ring. Pure elastomer lip seals or double groove seals are designed for compression in the housing and for expansion at the shaft diameter.

[0010] Metal composite seals are pressed firmly onto the housing and stretched along the shaft diameter and are often secured to the shaft diameter by a worm spring.

[0011] For a secure and permanent seal between the dynamically moving rotary valve shaft and the housing, it is necessary that the respective seal sits securely in the housing bore without lifting off, despite all mechanical and thermal requirements, and at the same time has sufficient preload on the shaft for a pressure-activated sealing function.

[0012] Pure elastomer seals such as elastomer lip rings and double grooved rings are subject to a thermal expansion factor that is significantly higher for elastomer materials than for the surrounding installation space components, which in the module essentially consist of high-performance plastics (PPS) with extreme filling levels.

[0013] The expansion or shrinkage of the seal body sometimes affects the sealing function over its lifetime, causing the seal to either shrink and lift off the static housing seat in subzero temperatures, or at least to have less sealing force, or shrink to the dynamic shaft diameter. Furthermore, the seal body can be pulled internally by tensile stresses due to eccentric dynamic movement of the shaft, causing it to lift off the outside of the housing sealing seat.

[0014] If the sealing body is structurally reinforced or compressed more strongly, this inevitably leads to more frictional wear on the dynamically stressed sealing lip and reduced flexibility of the dynamic sealing lips.

[0015] The seals must withstand a vacuum medium filling, whereby a sealing body design that is too unstable can lead to vacuum leakage.

[0016] Another problem can arise when the sealing pressure on the housing increases from time to time and on the dynamic shaft. This can cause the sealing lip to seize in the dynamic range, and the seal can be rotated on the outside of the static sealing seat, where a tight seal is supposed to be ensured.

[0017] Metal composite seals, which are manufactured using vulcanized stiffening rings and a sealing lip, offer a tight fit to the housing, but prevent the required flexibility due to their rigid connection to the composite body. A worm spring, which is attached to the dynamic sealing lip to maintain the sealing pressure, ensures greater tightness and offers eccentricity compensation, but also leads to wear due to increased sealing pressure on the dynamic sealing lip. This leads to wear marks on the dynamic shaft or wear on the dynamic sealing lip. Furthermore, the manufacturing costs for metal composite parts are correspondingly higher.

[0018] DE 92 13 374 U1 discloses a sealing ring for radially sealing an interface between two surfaces. The sealing ring has a retaining ring that can be connected to one of the two surfaces via a press fit. Task:

[0019] The support body is designed to hold the sealing element securely during or before assembly so that the support body and sealing element can be treated as bulk material.

[0020] When inserting the sealing body with the support body into the housing, the support body should remain connected to the sealing body even in the event of assembly friction in the axial direction and should not come loose.

[0021] When inserting the rotary valve shaft, the seal should not be moved or folded over.

[0022] The tight fit of the outer sealing lip on the housing must be ensured and not allow any movement, i.e. remain static, in order to prevent radial migration in the different temperature ranges and to stabilize the sealing body in the axial direction during vacuum filling and assembly of the shaft, so that the sealing body does not turn inside out, tilt or is pulled out of the sealing seat.

[0023] The sealing element should provide low-wear sealing in both centric and eccentric positions of the dynamically moving shaft, both at low system temperatures and in the high-temperature range. For the dynamic sealing task on the shaft, the main sealing lip facing the medium should exhibit sufficient flexibility and compliance and be able to bear more tightly against the shaft under medium pressure.

[0024] The shaft's plain bearing guide should be positioned as close as possible to the sealing element in order to keep the angular misalignment and the eccentricity of the shaft to the dynamic main sealing lip inside as small as possible. Solution:

[0025] The invention is based on the object that the support body 4 should hold the sealing element 2 captively during or before assembly, so that the support body 4 and the sealing element 2 can be treated as bulk material.

[0026] This task is solved by the support body 4 having an inwardly wedge-shaped contour, in which the sealing element 2 with the outer sealing lip 7 can snap into a form-fitting manner in the form of a pre-assembly ( Fig. 4). The form-fitting contours (16) wedge each other and together form a linked unit, which can be delivered as bulk material by the manufacturer and advantageously fed into the housing (3) for the main assembly process.

[0027] A further design is intended to ensure that when the sealing element 2 is inserted with the support body 4 into the housing 3, the support body 4 remains connected to the sealing element 2 even in the event of assembly friction in the axial direction.

[0028] Due to the wedge-shaped connection 16 between the support body 4 and the static sealing lip 14, the outer drop-shaped sealing lip 14 is pressed into the wedge-shaped undercut 16 on the support body 4 and thus remains firmly anchored to the support body 4 regardless of the frictional force of the insertion process between the housing 3 and the sealing element 2 and is statically pressed in a similar way to an O-ring.

[0029] When inserting shaft 1, the seal should not be moved or folded over.

[0030] This task is solved by the fact that the support body 4 is slightly larger at the inner diameter than the shaft diameter and can therefore be inserted centrally in a forced manner.

[0031] The main sealing lip 11 or secondary sealing lip 15 cannot fold over even during butt-fitting, as they are provided with an insertion bevel 20 and are additionally protected behind the support body 4. The sealing lips 11, 15 can deflect and expand unhindered in the radial direction.

[0032] A further advantage against the sealing element 2 being pushed out during assembly is the tight fit of the outer wedge-shaped pressed sealing lip 14. This prevents it from being unscrewed or pushed out of the housing 3.

[0033] A further design is intended to ensure that the outer sealing lip 14 is firmly seated on the housing 3 and does not allow any movement, i.e. to remain static.

[0034] This task is achieved in that the sealing element 2, which is linked to the support body 4, is inserted into the housing 3 with force axially into the housing sealing seat, whereby during this process the static sealing lip 14 is pressed radially and simultaneously in a form-fitting manner between the housing 3 and the support ring 4. The static sealing lip 14 is thus permanently and firmly chambered on the outside. This offers the advantage that the sealing element 2 is held firmly on the outside and no expensive vulcanized stiffening ring is required. The pressed-through outer sealing lip 14 thus has a higher sealing pressure force than the inner, dynamically acting one and remains statically tight at different temperatures and eccentricities of the shaft 1.

[0035] This function also has the advantage that the inner dynamic sealing seat and the outer static sealing seat seal separately from each other.

[0036] A further embodiment describes that the sealing element 2 is to seal with low wear when the dynamically moving shaft 1 is in a centric and eccentric position both at low system temperatures and in the high temperature range and is to bear more strongly against the shaft (1) when there is medium pressure.

[0037] This task is solved by the freely movable connection 12 between the static and the dynamic sealing lips 11, 15. The dynamic sealing lips 11, 15 can follow the eccentric movements of the shaft 1 more easily because the connecting web 12 is thin-walled compared to the main sealing lip 11 and secondary sealing lip 15 and offers movable space.

[0038] Furthermore, it is particularly advantageous that the support body 4 is recessed in the area of ​​the secondary sealing lip 15, thus providing a clearance 17 for a desired tilting effect of the main sealing lip 11 toward the sealing shaft 1 when system pressure is applied. The support body 4 forms a pivot point 18 on which the sealing body rests and, when pressure is applied, can tilt inward in an angular movement toward the shaft 1 to be sealed, thereby increasing its sealing effect proportionally to the system medium pressure.

[0039] A further embodiment describes that the plain bearing guide of the shaft 1 should be located as close as possible to the dynamic main sealing lip 11 of the sealing element 2 in order to keep the angular offset and eccentricity of the shaft 1 to the dynamic main sealing lip 11 inside as small as possible.

[0040] This is achieved by the close connection of support body 4 and sealing element 2. The support body 4 can be designed in such a way that it is compressed on the housing 3 and forms the plain bearing of the shaft 1 and thus an advantageous shaft guidance takes place directly next to the main sealing lip 11. Example:

[0041] The following invention is explained in more detail with reference to the drawing. Fig. 1 The installation situation according to the invention in a housing 3 of a coolant control valve and a shaft 1 with built-in seal consisting of support body 4 ( Fig. 2) and sealing element 2 ( Fig. 3) and a housing cover 5 in cross section. Fig. 2 Cross-section of an annular support body 4 made of plastic or metal. The support body 4 is provided with a raised, offset support body section 6 that projects into the sealing contour and has a wedge-shaped, recessed shoulder or undercut 16 on the outer diameter for receiving the static sealing lip 14, as well as a straight surface (formed by the support body section 6) that projects into the sealing body and serves as a support for the sealing connecting web (12). In addition, the support body section 6 has an inwardly offset, straight shoulder 7 and a base body 10 that serves as a plain bearing and for pre-centering the shaft 1. The straight surfaces 8, 9 on the support body 4 serve to stabilize and support the sealing lips 14, 15 during assembly and when subjected to system pressure. Fig. 3 Sealing element 2 with three-lip geometry shown in cross-section. This sealing element 2 forms a seal with a statically acting, wedge-shaped sealing lip 14, which can be directed upwards or downwards depending on the installation direction, as well as a flat, upwardly offset connecting web 12 for connecting the dynamically acting main sealing lip 11, which faces the media side on the inside and fulfills the primary sealing function, and a secondary lip 15, which is designed for secondary sealing functions and is directed towards the atmosphere. Fig. 4 Sealing element 2 shown in cross-section with a three-lip geometry connected to a support body 4, shown in cross-section in the connected state. The wedge shapes of the sealing geometry and the support body 4 interlock. The secondary lip 15 has a defined clearance to the straight sloping shoulder 7 of the support body section 6, with the connecting web 12 being freely movable in the axial direction. Fig. 5 Sealing element 2 shown in cross section with three-lip geometry linked to a support body 4 shown in cross section with main sealing lip 11 directed towards the medium side and outer lip 14 towards the atmosphere for a convenient mounting direction. Fig. 6 Sealing element 2 shown in cross section with three-lip geometry linked to a support body 4 shown in cross section with main sealing lip 11 and an outer lip 14 directed towards the medium side for convenient mounting direction. Fig.7 Sealing lip 22 shown straight without system pressure and sealing lip 21 shown tilted under system pressure. List of reference symbols 1 wave 2 sealing element 3 housings 4 support bodies 5 Housing cover 6 Offset support body section 7 Straight heel 8 support surface 9 Support surface 10 soil bodies 11 Main sealing lip dynamic 12 connecting bridge 13 Static sealing lip 14 Static sealing lip 15 Secondary sealing lip 16 Wedge-shaped undercut 17 Free space for secondary lip 18 Pivot point 19 mounting centering diameter 20 Lead-in chamfer secondary sealing lip 21 Sealing lip in tilted position 22 Sealing lip in straight state 23 Outer lip facing the atmosphere 24 Outer lip facing the medium

Claims

[1] Asymmetrical annular sealing element (2), which is positively connected to an annular support body (4) made of plastic or metal as a composite part and dynamically seals a shaft (1), characterized by in that a static sealing lip (14) of the sealing element (2) is statically pressed and firmly chambered by the support body (4), and wherein a main sealing lip (11) with a secondary lip (15), which are connected to the static sealing lip (14) by a connecting web (12), bear against the shaft (1) in the dynamic sealing area, and a tilting effect towards the shaft (1) is brought about by a cavity (17) between the secondary lip (15) and a straight shoulder (7) of the support body (4) when pressure is applied. [2] Sealing element (2) according to claim 1, characterized by that the static sealing lip (14) of the sealing element (2) is wedge-shaped and is linked to a wedge-shaped support body (4). [3] Sealing element according to claim 1 or 2, characterized by that the static sealing lip (14) is directed towards the media side or towards the atmosphere side depending on the mounting direction and is modeled on the wedge-shaped contour on the support body (4). [4] Sealing element according to one of the preceding claims, characterized by that the connecting web (12) forms a connection between the static sealing lip (14) and the dynamic radially acting main sealing lip (11) as well as the secondary lip (15), which is directed inwards towards the media side and this connecting web (12) in the region of the cavity (17) between the secondary lip (15) and the straight shoulder (7) of the support body (4) can yield when pressure is applied and causes a tilting effect towards the shaft (1). [5] Sealing element according to one of the preceding claims, characterized bythat the sealing element (2) has a radially acting secondary lip (15) which is designed for secondary sealing functions and is directed towards the atmosphere. [6] Support body for a sealing element (2) according to one of the preceding claims, characterized by in that the support body (4) is designed for positive reception during pre-assembly of the seal (2) and has a support body section (6) which is raised in a ring shape in the middle of the support body (4), which has a wedge-shaped recessed shoulder (5) on the outer diameter for receiving the static sealing lip (14) and a straight shoulder (7) inwards towards the secondary lip (15), wherein the support body (4) has an inwardly wedge-shaped contour on the shoulder (5) into which the sealing element (2) can be snapped in a positive fit with the outer sealing lip (14). [7] Support body according to claim 6, characterized bythat the support body (4) is designed with a base body (10) which serves as a sliding bearing for the dynamically moving rotary valve shaft (1) and provides support surfaces (8, 9) for the sealing element (2). [8] Arrangement comprising a sealing element (2) according to one of claims 1 to 5 and a supporting body (4), characterized by that the arrangement is constructed from two parts, can be linked together and can be inserted into a housing (3) in this linked state. [9] Arrangement according to claim 8, characterized by that a rotary valve shaft can be inserted into an annular inner sealing contour and is sealed by the sealing element (2).

Images