Covers for worm wheel gearboxes, worm wheel gearboxes for steering systems, and electric steering systems for vehicles.

Abstract

The present invention relates to a cover (20) for a worm wheel gearbox (10), the cover (20) having - a substantially disc or dome-shaped cover body (30) configured to cover an opening (11) of the worm wheel gearbox (10), -- the cover body (30) includes an inner surface (32) positioned to face the worm wheel gearbox (10) and an outer surface (31) on the opposite side, -- the cover body (30) is formed on the inner surface (32) and the opening (11) of the worm wheel gearbox (10) The present invention relates to a cover (20) comprising a sealing portion (34) configured to be in close contact with the outer circumference (15) of the cover body (30), wherein the cover body (30) comprises a first mounting means (23) and a second mounting means (24) for attaching the cover body (30) to the worm wheel gearbox (10), the first mounting means (23) and the second mounting means (24) are provided at substantially opposite diametrically from the cover body (30), and the cover body (30) comprises a reinforcing structure (40) for reinforcing the cover body (30).

Description

Technical Field

[0004]

[0001] The present invention relates to a cover for a worm wheel gear box, a steering system worm wheel gear box including this cover, and an electric power steering system for a vehicle including the worm wheel gear box and the cover.

Background Art

[0002] In the prior art, electric and hydraulic assist steering systems for assisting a vehicle driver during steering are known, and the vehicle driver only needs to apply a relatively small force to steer the vehicle in a desired direction. In an electric assist steering system, an electric motor supplies turning force to a rack bar via a steering assist gear. This steering assist gear is encapsulated by a closable gear box, and the closable gear box is particularly subject to stress due to the temperature difference of the closable gear box between the normal temperature state and the heated state when the vehicle is being driven normally. This temperature difference and the resulting pressure may particularly involve the risk of leakage of the lubricant contained in the closable gear box, as well as the risk of contamination particles and fluids entering from outside the closable gear box.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In view of the above, an object of the present invention is to provide a cover for a worm wheel gear box that can be easily manufactured and attached, which ensures an increase in the service life of the worm wheel gear box to be closed by this cover, and particularly improves the sealing performance of the worm wheel gear box.

[0004] Furthermore, an object of the present invention is to provide a worm wheel gearbox electric steering system that ensures easy manufacturing and installation, increases the service life of the steering assistance means for the driver, and in particular improves the sealing of the worm wheel gearbox. [Means for solving the problem]

[0005] These challenges are addressed by the claims in the independent form. Preferred embodiments are described in the dependent claims.

[0006] From one perspective, this is a cover for a worm wheel gearbox, and this cover is, - Having a substantially disc or dome-shaped cover body configured to cover the opening of the worm wheel gearbox, The cover body includes an inner surface positioned to face the worm wheel gearbox and an outer surface on the opposite side. The cover body includes a sealing portion formed on its inner surface and configured to tightly adhere to the outer circumference of the opening of the worm wheel gearbox. The cover body includes a first mounting means and a second mounting means for attaching the cover body to the worm wheel gearbox, the first mounting means and the second mounting means being provided at substantially opposite diametrically opposed positions of the cover body. The provided cover is characterized in that the cover body includes a reinforcing structure that reinforces the cover body.

[0007] The reinforcing structure of the cover body allows the cover to reliably close and seal the worm wheel gearbox, especially pressurized or stressed type worm wheel gearboxes, and to store lubricant with a reduced risk of leakage, thus reducing the risk of contamination in the worm wheel gearbox. It also improves the efficiency of the electric steering system, thereby assisting the driver in steering the vehicle more easily over an extended service life.

[0008] Furthermore, the combination of the reinforcing structure and the first and second mounting means on opposite sides in the diametrical direction allows the cover to be easily mounted and to precisely define the load path from the first mounting means to the second mounting means via the intermediately provided reinforcing structure. Based on these load paths, the cover body can be structurally optimized between rigidity and weight, and the upper limit of the load that the cover must withstand can be precisely determined based on the load paths. Thus, the reinforcing structure of the cover enables the worm wheel gearbox to be sealed cost-effectively with a cover that can be easily manufactured.

[0009] Furthermore, by precisely defining the load path between the first and second mounting means, even if the sealing portion is obstructed, it is within the permissible limits, or the load can be accurately guided through the reinforcing structure in a load path that does not obstruct the sealing portion. Thus, the reliable sealing of the worm wheel gearbox by the cover is improved over the increased service life.

[0010] Furthermore, the reinforcing structure that provides a robust and precisely defined load path between the first and second mounting means particularly improves noise attenuation, thereby increasing the service life of the worm wheel gearbox, while also improving the ride comfort of the vehicle.

[0011] Thus, the cover of the present invention can increase the service life of the worm wheel gearbox while ensuring the efficient manufacture and installation of the cover.

[0012] In certain embodiments, the cover body is configured to be removably attached to the worm wheel gearbox. For example, the first and second mounting means are removable mounting means for the cover to corresponding mounting means on the worm wheel gearbox.

[0013] A removable cover can, advantageously, ensure the maintainability of the worm wheel gearbox.

[0014] In certain embodiments, the first and / or second mounting means protrude from the cover body, particularly substantially, within the plane in which the disc or dome-shaped cover body has its main extent. In other words, the first and / or second mounting means may protrude substantially radially from the disc or dome-shaped cover body. In the exemplary embodiments, the first and / or second mounting means are positioned at the radially outer edge portion of the cover body, or substantially at the radially outermost portion.

[0015] The first and / or second mounting means protruding from the cover body can, in particular, form a continuous reinforcing structure to the cover body, especially between the first and second mounting means, thereby allowing for a precise load path to be defined between the first and second mounting means.

[0016] In certain embodiments, the cover body has only a first mounting means and a second mounting means for attaching or installing the cover to the worm wheel gearbox, in particular for attaching or installing the cover to the opening of the worm wheel gearbox, so as to tightly close the opening of the worm wheel gearbox.

[0017] In another specific embodiment, the first and second mounting means do not include adhesive for attaching the cover to the worm wheel gearbox, particularly for attaching the cover to the opening of the worm wheel gearbox. In other words, the cover can be attached or installed to the worm wheel gearbox in an adhesive-free manner.

[0018] With the separately defined first and second mounting means, the cover can more precisely define the cover load path that the cover imposes on it, for example, due to a heated lubricant when the worm wheel gearbox is pressurized.

[0019] In certain embodiments of the cover, the cover may have a flange portion that extends substantially circumferentially around a substantially disc or dome-shaped cover body, particularly at the top of the cover, i.e., on the outer surface.

[0020] The flange portion is advantageous in that it improves the handling of the cover, for example, when attaching the cover to the worm wheel gearbox. Furthermore, the flange portion is advantageous in that it can secure the sealing member to the sealing portion of the cover in order to make a tight fit with the opening of the worm wheel gearbox. The flange portion is preferably formed adjacent to the sealing portion, and also, due to its substantially circumferential extension, it can prevent the sealing member from being pushed away from the cover and its sealing portion during the attachment of the cover to the worm wheel gearbox.

[0021] In the exemplary embodiment, the disc or dome-shaped cover body is preferably substantially circular when viewed in a plan view. However, the disc or dome-shaped cover body is not limited thereto, and its shape may deviate from a strictly circular shape, for example, when viewed in a plan view, i.e., when viewed from above, the disc or dome-shaped cover body may be substantially elliptical, rectangular, or other polygonal.

[0022] Compared to a disc-shaped cover body that includes a substantially planar outer surface, a dome-shaped cover body has a convex shape that curves outward, that is, it includes a convex apex that has a height that increases particularly toward the middle part of the cover body.

[0023] In another exemplary embodiment, the cover may have a substantially tubular-shaped portion that extends from the outer surface towards the inner surface. The substantially tubular-shaped portion may particularly include a sealing portion. The sealing portion may have, for example, one or more grooves or recesses that extend, for example, substantially circumferentially around this tubular portion. Thus, the sealing portion may have one or more sealing members, such as one or more O-rings, at each of the grooves or recesses to increase the tightness when the cover is attached to the worm wheel gearbox. In accordance with the disc or dome-shaped cover body, the substantially tubular-shaped portion may particularly have a substantially circular cross-section, but is not limited thereto and may have a substantially elliptical, rectangular, or other polygonal cross-section.

[0024] The substantially tubular portion may be configured to at least partially extend into the opening of the worm wheel gearbox when the cover is in an attached or installed state relative to the worm wheel gearbox, the purpose being to close the worm wheel gearbox in a sealable or tight manner.

[0025] The cover may particularly have a disc or dome-shaped top at the distal end of the substantially tubular portion, i.e., at the top end of the substantially tubular portion. Thus, the disc or dome-shaped top can be configured to at least partially form the outer surface when viewed in a plan view, i.e., a plan view towards the outer surface.

[0026] In certain embodiments, the first attachment means and / or the second attachment means have attachment holes configured to removably receive corresponding attachment means of the worm wheel gearbox, such as screws, pins, and / or clips. In other certain embodiments, the first attachment means and / or the second attachment means can include attachment protrusions that releasably engage corresponding attachment means of the worm wheel gearbox, such as screws, pins, and / or clips. In certain embodiments, the first attachment means and / or the second attachment means may be configured to form a releasable push-fit engagement and / or a releasable friction-fit engagement with the corresponding attachment means of the worm wheel gearbox.

[0027] As used herein, when the modifier "substantially" or "about" is given to a direction, each direction is to be understood as deviating from that direction by up to 10°, preferably up to 5°, in the range from 0° to 10°, preferably from 0° to 5°.

[0028] As used herein, when the modifier "substantially" or "about" is given to a measured value or quantity, each measured value or quantity is to be understood as deviating from that measured value or quantity by up to 10%, preferably up to 5%, in the range from 0% to 10%, preferably from 0% to 5%.

[0029] The direction from the first attachment means to the second attachment means, which is substantially diametrically opposite, is illustratively shown herein as the longitudinal direction.

[0030] The direction that is substantially perpendicular to the longitudinal direction and extends substantially within a plane including the major spread of the cover is illustratively shown as the width direction.

[0031] The direction from the inner surface of the cover body to the substantially opposite outer surface is exemplified as the height direction. The height direction is particularly preferably substantially perpendicular to the length and / or width direction. Therefore, when referring to the lower or bottom side of the cover, it refers to the inner surface, and when referring to the top or upper side of the cover, it refers to the outer surface.

[0032] When we speak of the radial direction or radius, such direction is assumed to lie within a plane defined by the length and width directions extending outward from the middle portion of the cover or cover body. Such middle portion is assumed to be part of the axis of a substantially tubular portion of the cover, which is particularly preferable in the case of a cylindrical tubular section to be part of the axis of rotational symmetry with respect to the substantially tubular portion.

[0033] In certain embodiments of the cover, the reinforcing structure of the cover body may include an outer reinforcing structure provided on the outer surface and / or an inner reinforcing structure provided on the inner surface.

[0034] In other words, the reinforcing structure of the cover body preferably includes an upper reinforcing structure and / or a lower reinforcing structure. In other words, the cover preferably has an outer reinforcing structure that extends particularly on the outer surface, and / or includes an inner reinforcing structure that extends particularly on the lower side of the cover body, i.e., located particularly on the opposite side of the outer reinforcing structure.

[0035] On the other hand, one separate reinforcing structure can precisely define the load path within the cover, particularly between the first and second mounting means, while two separate reinforcing structures can distribute the pressure load separately, while also enabling the fabrication of a cover with a relatively low height.

[0036] Therefore, the external and / or internal reinforcing structures effectively ensure an increased service life for the cover, while also facilitating the fabrication and installation of the cover and, in particular, reducing its weight.

[0037] In certain embodiments of the cover, the reinforcing structure may include an outer reinforcing structure extending from a first mounting means to a second mounting means.

[0038] In another specific embodiment, the outer reinforcing structure may extend from immediately adjacent to the first mounting means to immediately adjacent to the second mounting means.

[0039] In other words, the external reinforcing structure can, in particular, provide direct load transfer between the first mounting means and the second mounting means on the diametrically opposite side. This direct load transfer is especially preferable to be related to the geometrically shortest possible path between the first and second mounting means.

[0040] Thus, the load between the first mounting means and the second mounting means can be advantageously guided through a predetermined and particularly reinforced portion of the cover body without affecting other parts of the cover body, in particular, which ensure a tight closure of the worm wheel gearbox.

[0041] In certain embodiments of the cover, the first mounting means is often a first mounting hole, the second mounting means is often a second mounting hole, and the outer reinforcing structure preferably extends continuously from the wall directly surrounding the first mounting hole to the wall directly surrounding the second mounting hole.

[0042] On the other hand, the first and second mounting means, which are mounting holes, advantageously facilitate the manufacture of the cover and make it easier to removably attach the cover to the worm wheel gearbox, and the outer reinforcing structure that extends continuously between the walls directly surrounding these holes further enhances the load guidance between the first and second mounting means.

[0043] In certain embodiments of the cover, the outer reinforcing structure may be a rib extending from a first mounting means to a second mounting means.

[0044] In other words, the outer reinforcing structure is preferably a rib that extends outward or upward from the outer surface and between the first mounting means and the second mounting means.

[0045] The ribs advantageously enhance the precise guidance of the load between the first and second mounting means. Furthermore, the ribs advantageously increase the bending rigidity of the cover, thereby reducing the likelihood that the cover will bend, buckle, or otherwise deform or be damaged when tightly closing the pressurized interior of the worm wheel gearbox.

[0046] In the exemplary embodiment, the rib is preferably substantially linear between the first and second mounting means, that is, substantially in the longitudinal direction where the first and second mounting means are located on opposite sides in the diametrical direction.

[0047] In the exemplary embodiment, when the first and second mounting means are formed as mounting holes, these mounting holes preferably form substantially tubular or axial extensions. The ribs preferably extend in particular from the tubular enclosure of the mounting hole of the first mounting means to the tubular enclosure of the mounting hole of the second mounting means. The ribs preferably have substantially the same width in the height direction, i.e., substantially axially, of each mounting hole as the respective mounting holes formed by the tubular enclosures. This is advantageous in ensuring smooth load guidance from the mounting means to the ribs.

[0048] The ribs preferably have increased height towards the middle of the cover body and, consequently, decreased height towards the respective first and second mounting means, which advantageously increases the bending rigidity of the cover.

[0049] In certain embodiments of the cover, the outer reinforcing structure may have a cross-section that increases toward the first and second mounting means, respectively. In particular, the cross-section of the outer reinforcing structure may decrease toward the middle portion of the cover body from the respective first and second mounting holes.

[0050] The cross-section of the outer reinforcing structure located immediately adjacent to each of the mounting means is preferably substantially coincided with the cross-section of the respective first or second mounting means. This is advantageous in ensuring a smooth load guidance from the mounting means to the outer reinforcing structure. Furthermore, since the cross-section of the outer reinforcing structure decreases toward the middle, a continuously widening cross-section can be avoided, which can lead to undesirable shrinkage of the cover or undesirable shrinkage of the holes inside the cover, especially when forming the cover, for example when the cover is injection molded.

[0051] In certain embodiments of the cover, the reinforcing structure may include an internal reinforcing structure that extends substantially across or throughout the inner surface.

[0052] The internal reinforcing structure can further enhance the rigidity of the cover, particularly its bending rigidity. Furthermore, the internal reinforcing structure can reinforce the sealing portion, especially from the radially inward portion on the inner surface, thereby ensuring a tight closure of the worm wheel gearbox by the cover.

[0053] The sealing portion formed on the inner surface and configured to be in close contact with the opening of the worm wheel gearbox is preferably formed as at least one substantially circumferential groove on the outer circumference of a substantially tubular portion of the cover body configured to extend into the opening of the worm wheel gearbox. It is preferable that one or more sealing members be provided at least partially within at least one substantially circumferential groove.

[0054] The internal reinforcing structure is preferably formed inside the substantially tubular portion of the cover body in which the sealing portion is formed, and more particularly substantially radially inward. In certain embodiments, the internal reinforcing structure is preferably configured to extend across the substantially radially inward portion of the tubular portion, and more particularly preferably directly connected to the substantially tubular portion. Furthermore, the internal reinforcing structure is preferably configured to extend along the lower or bottom side of the disc or dome-shaped cover body.

[0055] Therefore, the internal reinforcing structure advantageously increases the rigidity of the cover and, more specifically, reinforces the inner surface of the cover from the radially inward direction, thus improving the tight closure of the worm wheel gearbox by the cover over a relatively long service life.

[0056] In certain embodiments of the cover, the internal reinforcing structure may include a honeycomb structure.

[0057] In a modified embodiment of the cover, the inner reinforcing structure may include a particularly segmented or branched web-like structure having separate wall portions extending across the inner surface of the other structure, the cover body, in which case valley portions with reduced material thickness are formed between adjacent wall portions.

[0058] Therefore, the internal reinforcing structure can advantageously increase the rigidity of the cover and reinforce the sealing portion from the radially inward direction, while the valleys prevent an excessive increase in the weight of the cover. Thus, the internal reinforcing structure, including honeycomb structures and / or other segmented or branched structures, can effectively increase the rigidity of the cover and reinforce the sealing portion, thereby extending the life of the tight closure of the worm wheel gearbox by the cover.

[0059] In this regard, the applicant has surprisingly found that a honeycomb structure as an internal reinforcing structure for the cover includes a plurality of substantially hexagonal honeycomb-like sections extending across the inner surface of the cover body, and such a honeycomb structure can effectively increase rigidity and reinforce the sealing portion, while at the same time preventing an excessive increase in the weight of the cover, thereby effectively ensuring the service life of the tightly closed pressurized worm wheel gearbox.

[0060] In certain embodiments of the cover, the honeycomb structure may include honeycomb wall portions and substantially hexagonal valley portions provided between the honeycomb wall portions.

[0061] In the exemplary embodiment, the honeycomb wall portion of the honeycomb structure preferably has a wall thickness (thickness) in the range of about 0.8 mm to about 4.0 mm, preferably in the range of about 1.2 mm to about 3.6 mm, and more preferably in the range of about 2.0 mm to about 3.0 mm. A given range of wall thickness for the honeycomb wall portion is advantageous because it provides an effective rigidity-to-weight ratio while being easy to manufacture.

[0062] In particular embodiments of the cover, the honeycomb structure may include a plurality of honeycomb sections, namely at least seven fully formed honeycomb sections arranged around the center of the cover body and a plurality of partially formed honeycomb sections, each extending between the fully formed honeycomb sections and the sealing section.

[0063] In other words, the honeycomb structure may include a plurality of honeycomb sections, each containing at least one fully formed honeycomb section, and a plurality of partially formed honeycomb sections adjacent to and surrounding the at least one fully formed honeycomb section. For example, the honeycomb structure may include at least seven fully formed honeycomb sections on the inner surface of the cover body. The plurality of honeycomb sections, in particular at least seven fully formed honeycomb sections, may be substantially uniform in shape. With respect to a substantially hexagonal honeycomb structure, a plurality of fully formed honeycomb structures may form at least one intermediate honeycomb structure at the center or middle of the cover body, which is adjacently surrounded by six honeycomb structures. Such intermediate honeycomb structures may be surrounded by other honeycomb structures, and in particular, they may be surrounded by partially formed honeycomb structures, each including a honeycomb wall portion that extends to the inner circumference of the sealing portion.

[0064] In certain embodiments of the cover, the honeycomb structure may have 7 to 19 fully formed honeycomb-like sections around the center of the cover body.

[0065] At least seven, and especially seven to nineteen, fully formed honeycomb sections can effectively increase the rigidity of the cover from the radially inward direction and reinforce the sealing portion, thereby ensuring a tight closure or tight seal of the worm wheel gearbox by the cover over an extended service life.

[0066] In certain embodiments of the cover, the cover may be a molded plastic part.

[0067] For example, the cover is preferably an injection-molded part, especially a one-piece injection-molded part.

[0068] In exemplary embodiments, the cover may include or consist of plastic, particularly polyamide, polypropylene, and / or polyethylene, or fiber-reinforced plastic, such as glass fiber-reinforced polyamide, glass fiber-reinforced polypropylene, and / or glass fiber-reinforced polyethylene. In another exemplary embodiment, the cover may include or consist of aluminum, and more particularly, may be die-cast from aluminum.

[0069] Molded parts, particularly injection-molded plastic parts or die-cast aluminum parts such as covers, are advantageous in that they ensure efficient and repeatable precision manufacturing.

[0070] In another particular embodiment of the cover, the cover body may have one or more inlays and / or spacers at the locations of the first and / or second mounting means. The cover body may have at least one inlay and / or spacer at each of the first and second mounting means. The inlays and / or spacers may be shaped to coincide with the first and / or second mounting means, and may also be substantially tubular inserts configured to surround the first and second mounting holes, respectively.

[0071] In the exemplary embodiment, the inlay and / or spacer are often incorporated into the cover body by multi-part molding, particularly multi-part injection molding, which advantageously facilitates the firm integration of the inlay and / or spacer into the cover body.

[0072] The inlays and / or spacers can advantageously increase rigidity locally, thus advantageously reinforcing load paths within the cover body, and particularly between mounting means on opposite diametrically opposite sides. Furthermore, the inlays and / or spacers integrated at the first and second mounting means, respectively, advantageously increase resistance to surface pressure from the fixing members for mounting the cover body to the worm wheel gearbox, for example, in the case of screw head contact at the mounting means.

[0073] In certain embodiments of the cover, the sealing portion may have an outer diameter in the range of about 60 mm to about 170 mm, preferably in the range of about 100 mm to about 140 mm.

[0074] In other words, the cover is preferably configured to act as a sealing closure for the opening of the worm wheel gearbox, the opening of the worm wheel gearbox having a diameter in the range of about 60 mm to about 170 mm, preferably at least about 100 mm, and more preferably in the range of about 100 mm to about 140 mm.

[0075] The aforementioned diameter of the sealing portion and the cover formed thereunder (which preferably has a flange extending in a range of approximately 2 mm to over 6 mm in diameter) allows the cover to advantageously close or tightly seal the opening of the worm wheel gearbox of the vehicle's steering system over an extended service life.

[0076] From another perspective, a worm wheel gearbox for a steering system, the worm wheel gearbox is, - It has a worm wheel connected to a pinion, and the pinion is configured to engage with a rack bar for displacing the steering wheels of the vehicle. - Having a worm wheel and a worm in a lubricated engagement state, - It has an opening for assembling the engagement portion between the worm wheel and the worm, A worm wheel gearbox is provided, characterized by having a cover from the above viewpoint relating to the cover for covering the opening.

[0077] The preferred and alternative viewpoints and embodiments of the above-described examples of covers also apply to worm wheel gearboxes, respectively, along with these advantageous effects, and vice versa.

[0078] A worm wheel gearbox can reliably support the steering of the vehicle's wheels over an extended service life.

[0079] From yet another perspective, an electric steering system for a vehicle, the electric steering system is - A rack bar for displacing the steering wheels of a vehicle, - A worm wheel gearbox equipped with a cover relating to the above-mentioned viewpoint regarding the cover, An electric steering system is provided, characterized by including a power supply unit that supplies power to the worm gear.

[0080] The preferred and alternative viewpoints and embodiments of the above-described examples of covers, along with their respective advantages, apply to electric steering systems, and vice versa.

[0081] A worm wheel gearbox in an electric steering system for a vehicle is particularly likely to have a cover. The cover is particularly likely to be sealed or fitted to an opening in the cover to tightly close the worm wheel gearbox, with the aim of preventing lubricant leakage from the worm wheel gearbox over an extended service life.

[0082] In an exemplary embodiment, the power supply unit is preferably configured to receive an input signal initiated by the driver turning the vehicle's steering wheel. When the vehicle's steering wheel is turned and the power supply unit receives the corresponding input signal, the power supply unit is preferably configured to supply power to a worm, which in turn supplies power to a worm wheel through its engagement with the worm wheel, and the worm wheel is particularly configured to supply power to a rack bar via a pinion. The rack bar is preferably, but is not limited to, supplied power in the vehicle width direction to perform steering motion of the steering wheels. In another exemplary embodiment, the input signal is preferably initiated by a vehicle control unit sending a steering command as an input signal to the power supply unit, for example, in an autonomous vehicle, without necessarily turning the vehicle's steering wheel.

[0083] On the other hand, the worm and worm wheel are preferably housed in a worm wheel gearbox, and the power supply unit is preferably located outside the worm wheel gearbox. Therefore, the power supply unit is preferably sealed and connected to the worm, which is at least partially located inside the worm wheel gearbox, in order to supply power to the worm wheel.

[0084] The worm wheel is particularly connected to a pinion, preferably concentrically connected to the pinion. Furthermore, in certain embodiments, the worm wheel and pinion are often connected to the same shaft so as to rotate together, which is advantageous in that it enhances the transmission of power from the worm to the pinion connected to the power supply unit.

[0085] In a preferred embodiment, the engagement between the pinion and the rack bar for displacing the vehicle's wheels is also housed within the worm wheel gearbox, which in particular facilitates lubricated engagement between the pinion and the rack bar. The power transmitted to the rack bar allows the rack bar to move in its axial direction, i.e., enabling lateral movement in the vehicle width direction, thereby favorably facilitating wheel steering. Thus, the worm wheel gearbox and its cover for sealing the worm wheel gearbox can provide effective electric steering assistance over an extended service life.

[0086] These objectives, features, and advantages of the present invention, as well as other objectives, features, and advantages, will become even clearer upon reading the following detailed description of preferred embodiments and the accompanying drawings. It should be understood that even when embodiments are described separately, these single features can be combined to form additional embodiments. [Brief explanation of the drawing]

[0087] [Figure 1a] This is an external view or schematic diagram of an electric steering system according to one embodiment of the present invention. [Figure 1b] Another external view or schematic diagram of an electric steering system as one embodiment of the present invention. [Figure 2a] This is a perspective view of a cover as an exemplary embodiment of the present invention. [Figure 2b] This is a cross-sectional view of a cover as an exemplary embodiment of the present invention. [Figure 3a] This is a plan view showing a cover as an exemplary embodiment of the present invention, facing the inner surface of the cover. [Figure 3b] This is a bottom view showing the cover as an exemplary embodiment of the present invention, facing outwards. [Modes for carrying out the invention]

[0088] Figure 1a is a schematic diagram of an exemplary electric steering system 1 as one embodiment of the present invention. Figure 1b is another schematic diagram of the electric steering system 1 as one embodiment of the present invention, and the electric steering system 1 shown in Figure 1b specifically corresponds to the electric steering system shown in Figure 1a.

[0089] As shown in Figure 1a, the exemplary electric steering system 1 includes a power supply unit 8, which is provided to power a rack bar 5 or assist its movement in order to steer the wheels of a vehicle (not shown), and in particular to power the rack bar 5 or assist its substantially axial movement.

[0090] As shown in Figures 1a and 1b, the power supply unit 8 is connected to the worm 9, which extends particularly into the worm wheel gearbox 10, shown in a partial cross-sectional view in Figure 1a and in a cross-sectional view in Figure 1b. Within the worm wheel gearbox 10, the worm 9 is meshed with the worm wheel 12, and as a result, the worm 9 transmits the driving force (power) of the power supply unit 8 to the worm wheel 12 to rotate the worm wheel 12.

[0091] The worm wheel 12 is connected to the pinion 14, which is engaged with the rack bar 5. Thus, the rotation of the worm wheel 12 is transmitted to the rack bar 5 by the pinion 14, and as a result, the rack bar 5 is displaced axially when the worm wheel 12 rotates.

[0092] As shown in Figure 1b, the worm wheel 12 and the pinion 14 are preferably mounted coaxially with each other, and in particular, they are preferably connected to a single shaft that transmits the rotation of the worm wheel 12 to the pinion 14. The axial displacement of the rack bar 5 is preferably particularly aligned with the left-right motion direction relative to the vehicle width direction so as to displace each wheel according to the driver's steering.

[0093] When the steering wheel is rotated by the driver (not shown) or when a steering command is initiated by the vehicle control unit (the rotation of the steering wheel or the steering command is configured to trigger an input signal which is sent to the power supply unit 8), the power supply unit 8 is preferably configured to receive this input signal, and in particular preferably to supply power to the worm 9 to drive the worm wheel 12 in response to this input signal, thereby causing the pinion 14 to rotate and further supply power to and displace the rack bar 5 in the direction in which the driver turns the steering wheel.

[0094] As shown in Figures 1a and 1b, the worm wheel gearbox 10 is closed in particular by a cover 10, and the cover 20 is attached to the opening 11 of the worm wheel gearbox 10, and in particular is in close contact with the outer circumference 15 of the opening 11 to tightly close or tightly seal the worm wheel gearbox 10. To tightly close or tightly seal the worm wheel gearbox 10 with the cover 20, a sealing member, such as an O-ring, is preferably provided between the outer circumference 15 of the opening 11 and the tubular portion 28 of the cover 20, as shown in particular in Figures 2a, 2b and 3a.

[0095] Figure 2a shows a cover 20 as an exemplary embodiment of the present invention in an oblique view. Specifically, the cover 20 shown in Figure 2a preferably corresponds to the cover 20 shown in Figures 1a and 1b.

[0096] Figure 2b shows a cross-sectional view of a cover 20 as an exemplary embodiment of the present invention. Specifically, the cover 20 shown in Figure 2b preferably corresponds to the cover 20 shown in Figures 1a, 1b, and 2a.

[0097] Figure 3a is a plan view showing a cover 20 as an exemplary embodiment of the present invention, facing the inner surface 32 of the cover 20. Specifically, the cover 20 shown in Figure 3a preferably corresponds to the cover 20 shown in Figures 1a, 1b, 2a, and 2b.

[0098] Figure 3b is a bottom view showing a cover 20 as an exemplary embodiment of the present invention, facing the outer surface 31 of the cover 20. The cover 20 shown in Figure 3b preferably corresponds to the cover 20 shown in Figures 1a, 1b, 2a, 2b, and 3a.

[0099] As shown in Figures 2a, 2b, 3a, and 3b, the cover 20 may in particular have a substantially circular cover body 30, in which case the first mounting means 23 and the second mounting means 24 each protrude substantially radially outward from the substantially circular shape of the cover body 30.

[0100] The first mounting means 23 and the second mounting means 24 are located on opposite sides of the cover body 30 in the diametrical direction, in particular. The longitudinal direction L is illustrated exemplarily as the direction in which the first and second mounting means 23, 24 are located on opposite sides of the diametrically direction. The width direction B is drawn substantially perpendicular to the longitudinal direction L and lies in the same plane as the longitudinal direction L, in which the cover body 30 has its greatest extent, as particularly emphasized in Figure 2b. The height direction H is directed from the lower side or inner surface 32 of the cover body 30 to the upper side or outer surface 31 of the cover body 30. The middle section M of the cover body 30 is illustrated exemplarily in Figures 2a, 2b, 3a, and 3b, and this middle section substantially coincides with the middle section of the substantially circular cover body 30.

[0101] Referring to Figures 1a and 1b, it can be seen that the upper or outer surface 31 and the lower or inner surface 32, as shown in Figures 2a, 2b, 3a, and 3b, do not need to coincide with the lower or upper surface with respect to the mounting or installation state in the vehicle, as illustrated in Figures 1a and 1b. More specifically, comparing Figures 1a and 1b with Figures 2a, 2b, 3a, and 3b, it should be understood that the inner surface 32 of the cover body 30 particularly relates to the interior of the worm wheel gearbox 10 and the side or surface of the cover body 30 facing the outer circumference 15 of the opening 11 of the worm wheel gearbox 10 when the cover 20 is mounted or installed in relation to the worm wheel gearbox 10. Therefore, the outer surface 31 of the cover body 30 is particularly related to the side or surface of the cover body 30 that faces away from the inside of the worm wheel gearbox 10 when the cover 20 is attached to or installed in relation to the worm wheel gearbox 10.

[0102] As shown in Figures 2a, 2b, and 3a, the cover body 30 preferably includes a substantially tubular portion 28 configured to extend downward in the height direction H from the disc or dome-shaped top portion 36 of the cover body 30. Thus, the substantially tubular portion 28 is configured to extend into the opening 11 of the worm wheel gearbox 10, and more particularly to face at least partially toward the outer circumference 15 of the opening 11. A tight relationship is preferably obtained between the tubular portion 28 and the outer circumference 15 of the opening 11 (preferably forming a tight seal), and at least one sealing member (not shown) is preferably provided between the tubular portion 28 and the outer circumference 15 of the opening 11.

[0103] As shown in Figure 2b, the tubular body 30 preferably includes a sealing portion 34, particularly at its tubular portion 28, and the sealing portion 34 is preferably formed as one or more substantially circumferential recesses specifically configured to face the outer circumference 15 of the opening 11. The sealing member (not shown) is preferably provided at least partially at or within the sealing portion 34.

[0104] As shown in Figures 2a, 2b, 3a, and 3b, the cover body 30 may in particular include a first mounting means 23 and a second mounting means 24 for attaching the cover 20 to the worm wheel gearbox 10, preferably in a removable manner. The first and second mounting means 23 and 24 may in particular include mounting holes 25 and 26 for removably attaching the cover 20 to the worm wheel gearbox 10, for example, by bolts, screws, or clips.

[0105] As shown in Figures 2a, 2b, 3a, and 3b, the cover body 30 may include at least one reinforcing structure 40, that is, at least an outer reinforcing structure 41 provided on the outer surface 31 or an inner reinforcing structure 42 provided on the inner surface 32, and preferably both an outer reinforcing structure 41 and an inner reinforcing structure 42 provided on opposite sides of the substantially disc-shaped or dome-shaped top portion 36 of the cover body 30.

[0106] As shown in Figures 2a, 2b, and 3b, the outer reinforcing structure 41 particularly has or is a rib extending between the first mounting means 23 and the second mounting means 24, in which case the outer reinforcing structure 41 preferably transitions into the first mounting means 23 and the second mounting means 24 at positions opposite in the respective diametrical directions of the cover body 30. As shown in the cross-sectional view of Figure 2b, which is particularly cut at a plane defined by the length direction L and the height direction H, the outer reinforcing structure 41 particularly transitions into the wall 25 directly surrounding the first mounting means 23, and then, on the opposite diametrical direction, preferably transitions into the wall 26 directly surrounding the second mounting means 24.

[0107] In particular, as shown in Figures 2a and 3b, the outer reinforcing structure 41 preferably has a gradually increasing cross-section in the width direction B toward the first and second mounting means 23, 24.

[0108] As shown in Figure 2b, the cover body 30 preferably has a convex curved portion toward the upper part of the cover body 30. In other words, the cover body 30 preferably has a gradually increasing height toward the middle part M of the cover body 30 in the width-height direction H.

[0109] Furthermore, as shown particularly in Figures 2a, 2b, 3a, and 3b, the cover body 30 is preferably provided at the distal end or upper distal end of the tubular portion 28 and also has a flange portion 29 extending radially outward beyond the tubular portion 28. The flange 29 preferably includes first and second mounting means 23, 24, which are substantially extended in the height direction H in particular so that they can be attached accordingly to corresponding mounting means of the worm wheel gearbox 10.

[0110] As shown in Figures 2b and 3a, the reinforcing structure 42 is particularly likely to extend across the inner surface 32 of the cover body 30 and, more particularly, substantially downward in the height direction H from the disc or dome-shaped top 36 of the cover body 30.

[0111] The internal reinforcing structure 42 includes or is a honeycomb structure having honeycomb-like wall portions 46, the honeycomb-like wall portions 46 extending substantially downward in the height direction H from the top 36 of the cover body 30, in which case valley portions 47 extend between the honeycomb-like wall portions 46 in a substantially hexagonal shape, the valley portions 47 having a reduced wall thickness, particularly in the height direction H, compared to the honeycomb-like wall portions 46.

[0112] As shown in Figure 3a, the honeycomb structure 44 preferably extends inward of the tubular portion 28 between radially opposite portions of the tubular portion 28, and more preferably extends radially inward of the tubular portion 28. Preferably, the honeycomb wall portions 46 of the honeycomb structure 44 are formed to extend from one portion of the tubular portion 28 to substantially diametrically opposite portions of the tubular portion 28, and more preferably to extend to several circumferentially displaced portions of the tubular portion 28, i.e., to substantially cover the entire inner surface 32 radially inward of the tubular portion 28, or more particularly, to form a sealing portion 34. Thus, the honeycomb structure 44 of the inner reinforcement structure 42 is advantageously configured to reinforce the tubular portion 28 radially inward to ensure reliable sealing of the worm wheel gearbox 10 by the cover 20 over increasing service life. Furthermore, the ribs of the outer reinforcing structure 41 preferably extend directly adjacent to each other from the first mounting means 23 to the second mounting means 24, which is advantageous as it allows the load to be precisely guided through the outer reinforcing structure 41 in a load path that does not interfere with the sealing portion 34 in particular, thus further improving the reliable sealing of the worm wheel gearbox 10 by the cover 20 over an increasing service life.

[0113] As shown in Figure 3a, the honeycomb structure 44 is provided at least on the inner surface 32 of the cover body 30 and preferably includes seven fully formed honeycomb sections extending radially inward from the sealing portion 34, and more preferably includes seven fully formed honeycomb sections and twelve partially formed honeycomb sections, the honeycomb wall portions 46 of the partially formed honeycomb sections connecting the inner circumference of the tubular section 28, or in other words, the sealing portion 34, to the honeycomb wall portions 46 of the fully formed honeycomb sections in the middle M of the inner surface 32. The wall portions 46 of the partially formed honeycomb sections located closer to the inner circumference of the tubular section 28 or sealing portion 34 are advantageous in that they allow for reinforced contact between the cover 20 and the opening 11 of the worm wheel gearbox 10 in a dispersed state. [Explanation of symbols]

[0114] 1. Electric steering system 5. Rack Bar (Bar-shaped rack) 8 Power supply unit 9 Warm 10 Worm wheel gearbox 11 Opening 12 worm wheel 14 pinion 15 Outer perimeter of the opening 20 Covers 23 First mounting means 24 Second mounting means 25 The wall directly surrounding the first mounting means 26 The wall directly surrounding the second mounting means 28 Tubular section 29 Flange section 30 Cover body 31 External surface 32 Inner self 34 Sealing part 36 Top 40 Reinforcement Structures 41 Outer reinforcement structure 42 Internal reinforcement structure 44 Honeycomb Structure 46 Honeycomb-like wall section 47 Valley part B Width direction H (height direction) L (Length direction) M Middle section (middle part of the cover body)

Claims

1. A cover (20) for a worm wheel gearbox (10), wherein the cover (20) is - The worm wheel gearbox (10) has a substantially disc or dome-shaped cover body (30) configured to cover the opening (11), --The cover body (30) includes an inner surface (32) positioned to face the worm wheel gearbox (10) and an outer surface (31) on the opposite side. --The cover body (30) includes a sealing portion (34) formed on the inner surface (32) and configured to be in close contact with the outer circumference (15) of the opening (11) of the worm wheel gearbox (10), --The cover body (30) includes a first mounting means (23) and a second mounting means (24) for attaching the cover body (30) to the worm wheel gearbox (10), wherein the first mounting means (23) and the second mounting means (24) are provided at substantially opposite diametrically from the cover body (30), --The cover body (30) includes a reinforcing structure (40) that reinforces the cover body (30), and the cover (20).

2. The cover (20) according to claim 1, wherein the reinforcing structure (40) of the cover body (30) includes an outer reinforcing structure (41) provided on the outer surface (31) and / or an inner reinforcing structure (42) provided on the inner surface (32).

3. The cover (20) according to claim 1 or 2, wherein the reinforcing structure (40) includes an outer reinforcing structure (41) extending from the first mounting means (23) to the second mounting means (24).

4. The first mounting means (23) is a first mounting hole, and the second mounting means (24) is a second mounting hole. The cover (20) according to claim 3, wherein the outer reinforcing structure (41) extends continuously from the wall (25) directly surrounding the first mounting hole to the wall (26) directly surrounding the second mounting hole.

5. The cover (20) according to claim 3 or 4, wherein the outer reinforcing structure (41) is a rib extending from the first mounting means (23) to the second mounting means (24).

6. The cover (20) according to any one of claims 3 to 5, wherein the outer reinforcing structure (41) has a cross-section that increases toward the first mounting means (23) and the second mounting means (24).

7. The cover (20) according to any one of claims 1 to 6, wherein the reinforcing structure (40) includes an internal reinforcing structure (42) that substantially extends across or over the entire inner surface (23).

8. The cover (20) according to claim 7, wherein the inner reinforcing structure (42) includes a honeycomb structure (44).

9. The cover (20) according to claim 8, wherein the honeycomb structure (44) includes honeycomb-like wall portions (46) and substantially hexagonal valley portions (47) located between the honeycomb-like wall portions (46).

10. The cover (20) according to claim 8 or 9, wherein the honeycomb structure (44) includes at least seven fully formed honeycomb-like portions provided around the center of the cover body (30) and a plurality of partially formed honeycomb-like portions extending between the fully formed honeycomb-like portions and the sealing portion (34).

11. The cover (20) according to claim 10, wherein the honeycomb structure includes 7 to 19 fully formed honeycomb-like portions provided around the center of the cover body (30).

12. The cover (20) is a molded plastic part, according to any one of claims 1 to 11.

13. The cover (20) according to any one of claims 1 to 14, wherein the sealing portion (34) has an outer diameter in the range of about 60 mm to about 170 mm, preferably in the range of about 100 mm to about 140 mm.

14. A worm wheel gearbox (10) for a steering system (1), wherein the worm wheel gearbox (10) is - It has a worm wheel (12) connected to a pinion (14), and the pinion (14) is configured to engage with a rack bar (5) for displacing the steering wheels of the vehicle. - The worm (9) is in a lubricated engagement state with the worm wheel (12), - It has an opening (11) for assembling the engagement portion between the worm wheel (12) and the worm (9), - A worm wheel gearbox (10) having a cover (20) according to any one of claims 1 to 13 for covering the opening (11).

15. An electric steering system (1) for a vehicle, wherein the electric steering system (1) is - A rack bar (5) for displacing the steering wheels of the vehicle, - A worm wheel gearbox (10) according to claim 14, comprising a cover (20) according to any one of claims 1 to 13, - An electric steering system (1) including a power supply unit (8) that supplies power to the worm (9).

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