Worm gear mechanism and electric servo steering device with a worm gear mechanism

Abstract

A worm gear mechanism (30) comprises a lubricant supply section (51) that can supply lubricant adhering to an end face (33) of a worm wheel (32) to an engagement section (34). The lubricant supply section (51) comprises a lubricant receiving section (60) that is positioned to allow the lubricant receiving section (60) to come into contact with the lubricant adhering to the end face (33) of the worm wheel (32) and to receive the lubricant during rotation of the worm wheel (32), and to supply the received lubricant to the engagement section (34).

Description

TECHNICAL AREA

[0001] The present invention relates to an improved worm gear mechanism and an electric power steering device equipped with such a worm gear mechanism. STATE OF THE ART

[0002] There is a steering device equipped with a worm gear mechanism to reduce the steering effort required by a steering wheel. Typically, the steering device's worm gear mechanism comprises a worm, which is rotated by a drive force generated by an electric motor, and a worm wheel that meshes with the worm and transmits the drive force from the electric motor to a steering rack.

[0003] Since slippage occurs at the meshing surfaces between the screw and the screw, it is important to maintain the lubrication of these surfaces by applying lubricant. An example of a prior art technique for maintaining the lubrication of the meshing surfaces is disclosed in patent specification 1.

[0004] Patent specification 1 describes a plate-shaped lubricant retainer plate having a diameter larger than the outer diameter of a worm gear and attached to a lower end face of the worm gear. An outer circumferential edge of the lubricant retainer plate is bent upwards to prevent the lubricant from flowing radially outwards, and a plurality of ribs, which engage with the worm gear, are formed circumferentially on the outer circumferential edge of the lubricant retainer plate. According to this configuration, the lubricant can be retained on the engaging surfaces, thus maintaining their lubrication. LIBRARY PATENT PAPER

[0005] Patent specification 1: Unexamined Japanese publication no. 2009-248724 REVELATION OF THE INVENTION; TASK TO BE SOLVED BY THE INVENTION

[0006] When the worm gear mechanism is operated, some of the lubricant applied to the meshing surfaces inevitably flows off to the end face of the worm wheel. Lubricants have a high viscosity among lubricants. Since the lubricant flowing off the meshing surfaces adheres to the end face of the worm wheel, there is a need for improvement here.

[0007] One object of the invention is to provide a worm gear mechanism and an electric power steering system equipped with the worm gear mechanism, with which the lubrication condition can be maintained by lubricants. MEANS OF SOLVING THE TASK

[0008] According to a first aspect, a worm gear mechanism is provided, comprising: a worm that is rotated by a driving force generated by a drive source; a worm wheel that engages with the worm;and a lubricant supply section configured to supply lubricant adhering to an end face of the worm gear to an engagement section, wherein a section is defined as the engagement section in which the worm gear and the worm engage most deeply with each other when the end face of the worm gear is viewed in a direction along an axis of rotation of the worm gear, wherein the lubricant supply section comprises a lubricant receiving section provided in a position enabling the lubricant receiving section to come into contact with the lubricant adhering to the end face of the worm gear and to receive the lubricant during rotation of the worm gear, and which supplies the received lubricant to the engagement section.

[0009] According to a second aspect, the worm gear mechanism according to the first aspect preferably further comprises a housing that accommodates the worm and the worm wheel, wherein the lubricant supply section comprises a bearing section that supports an end section of the lubricant receiving section and which is integrally formed with the lubricant receiving section, and wherein the bearing section overlaps with and is attached to the housing.

[0010] According to a third aspect, in the worm gear mechanism according to the second aspect, the housing preferably comprises a container in which an opening is formed and a cover that closes the opening, wherein the bearing section is attached to the cover.

[0011] According to a fourth aspect, in the worm gear mechanism according to the first aspect, the lubricant receiving section preferably comprises a guide end section which is closest to the engagement section, as well as a face-proximal section which is provided by the guide end section along a straight line along the face of the worm wheel, wherein a plane which includes the axis of rotation of the worm wheel and the engagement section is defined as the reference plane, and wherein the face-proximal section is arranged such that, viewed in a direction along the axis of rotation of the worm wheel, it is inclined with respect to the reference plane.

[0012] According to a fifth aspect, in the worm gear mechanism according to the first aspect, the lubricant receiving section preferably comprises a lubricant receiving element section which includes a guide end section closest to the engagement section and is arranged such that it rests against the end face of the worm wheel, wherein a plane comprising the axis of rotation of the worm wheel and the engagement section is defined as the reference plane, and the lubricant receiving element section comprises an inclined section which is arranged such that it is inclined in a direction away from the reference plane with respect to a direction perpendicular to the end face of the worm wheel.

[0013] According to a sixth aspect, in the worm gear mechanism according to one of the first to fifth aspects, the lubricant supply section preferably comprises a weak point section that is weaker than surrounding sections of the lubricant supply section.

[0014] According to a seventh aspect, in the worm gear mechanism according to the sixth aspect, the weak point section is preferably provided at an end section of the lubricant receiving section or in the lubricant receiving section.

[0015] According to an eighth aspect, the worm gear mechanism according to the first aspect preferably further comprises a second lubricant supply section, which is provided in a position that allows the second lubricant supply section to come into contact with the lubricant adhering to the end face of the worm wheel and to absorb the lubricant during the rotation of the worm wheel, and which supplies the absorbed lubricant to the engagement section, wherein a plane comprising the axis of rotation of the worm wheel and the engagement section is defined as the reference plane, wherein the lubricant supply section is arranged on one side of the reference plane and the second lubricant supply section is arranged on the other side of the reference plane.

[0016] According to a ninth aspect, in the worm gear mechanism according to the eighth aspect, the second lubricant supply section preferably has a shape symmetrical with respect to the reference plane to the lubricant supply section.

[0017] According to a tenth aspect, in the worm gear mechanism according to the ninth aspect, the lubricant supply section and the second lubricant supply section are preferably integrally formed together and form a ring-shaped shape which, viewed along the axis of rotation of the worm wheel, surrounds the axis of rotation.

[0018] According to an eleventh aspect, an electric power steering device is provided, comprising: a worm gear that is rotated by a driving force generated by an electric motor; a worm wheel that engages with the worm gear and transmits the driving force of the electric motor to a steering rack;and a lubricant supply section configured to supply lubricant adhering to an end face of the worm gear to an engagement section, wherein a section is defined as an engagement section in which the worm gear and the worm engage most deeply when the end face of the worm gear is viewed in a direction along the axis of rotation of the worm gear, wherein the lubricant supply section comprises a lubricant receiving section provided in a position enabling the lubricant receiving section to come into contact with the lubricant adhering to the end face of the worm gear and to receive the lubricant during rotation of the worm gear, and which supplies the received lubricant to the engagement section. IMPACT OF THE INVENTION

[0019] The invention enables the provision of a worm gear mechanism that can maintain a lubrication condition by means of lubricant, as well as an electric power steering device that is equipped with a worm gear mechanism. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of an electric power steering device with a worm gear mechanism. Fig. Figure 2 is a perspective exploded view of the worm gear mechanism. Fig. Figure 3A shows a representation of a worm wheel and a worm viewed along an axis of rotation of the worm wheel. Fig. Figure 3B shows a representation of a lubricant supply element (lubricant supply section) along a rotational axis of the worm gear. Fig. Figure 4 is a perspective view of the lubricant supply section from below. Fig. Figure 5 shows the lubricant supply section and the worm gear mechanism viewed from the side. Fig. Figure 6A shows the lubricant supply section viewed from an engagement section in the direction of the axis of rotation of the worm gear. Fig. Figure 6B shows a cross-section of the lubricant intake section. Fig. Figure 7 is a representation showing the operating principle of the lubricant supply element (lubricant supply section). FORM(S) OF EXECUTION FOR IMPLEMENTING THE INVENTION<Ausführungsformen>

[0020] Embodiments are described with reference to the accompanying drawings. "L" denotes a left side, "R" a right side, "Up" a top side, and "Dn" a bottom side.

[0021] Referring to Fig. 1, comprising an electric power steering device 10, a steering device 20 extending from a steering wheel 21 of a vehicle to steerable wheels 29, 29 (for example, front wheels), and an auxiliary torque mechanism 11 that applies an assisting torque to the steering device 20.

[0022] The steering device 20 is a device in which a pinion shaft 24 is connected to the steering wheel 21 via a steering shaft 22 and universal joints 23, 23, a rack 26 (steering rack) is coupled to the pinion shaft 24 via a rack and pinion transmission 25, and the left and right steering wheels 29, 29 are each connected to the ends of the rack 26 via tie rods 27, 27 and steering knuckles 28, 28.

[0023] The rack and pinion transmission 25 comprises a pinion 24a formed on the pinion shaft 24 and a rack section 26a formed on the rack 26.

[0024] In the configuration described above, the driver can steer the left and right wheels 29, 29 by turning the steering wheel 21 via the rack and pinion drive 25 and the left and right tie rods 27, 27 by means of a steering torque.

[0025] The auxiliary torque mechanism 11 detects a steering torque exerted on the steering wheel 21 by means of the steering device 20 via a steering torque sensor 12, generates a control signal by means of a control unit 13 based on a torque detection signal from the steering torque sensor 12, generates an auxiliary torque corresponding to the steering torque based on this control signal by means of an electric motor 14 (drive source), and transmits this auxiliary torque to the rack 26 via a worm gear mechanism 30. However, the auxiliary torque mechanism 11 can also be configured to transmit an auxiliary torque generated via the worm gear mechanism 30 to the pinion shaft 24. (Worm gear mechanism)

[0026] Referring to Fig. 2, the worm gear mechanism 30 comprises a worm 31 which is driven by an electric motor 33 (see Fig. 1) generated driving force is rotated, a worm wheel 32 engaging with the worm 31 and a housing 40 that accommodates the worm 31 and the worm wheel 32. (Housing, axis of rotation)

[0027] The housing 40 comprises a container 41 in which an upwardly open opening 41a is formed, and a cover 42 that closes the opening 41a of the container 41. The cover 42 is attached to the container 41 by means of fastening elements 43, 43, for example, screws. A shaft section 32a of the worm gear 32 engages with the rack 26 (see figure). Fig. 1) An axis of rotation Ax of the shaft section 32a extends through the cover 42. (Procedure section)

[0028] Referring to Fig. 3A, is defined as engagement section 34 in which, viewed along the axis of rotation Ax of the worm wheel 32, an outer circumferential edge 33a of an end face 33 of the worm wheel 32 and the worm 31 engage most deeply into each other. (Lubricant supply element)

[0029] Referring to Fig. 2 to Fig. 3B, the worm gear mechanism 30 further comprises a lubricant supply element 50, which can supply lubricant adhering to the end face 33 of the worm wheel 32 to the engagement section 34. The lubricant supply element 50 is arranged between the cover 42 and the end face 33 of the worm wheel 32.

[0030] The lubricant supply element 50 consists of a resin. The resin from which the lubricant supply element 50 is formed contains long fibers, for example, glass fibers or carbon fibers. However, the material from which the lubricant supply element 50 is formed can also be metal or the like, or consist of any other material, provided it has a predetermined stiffness. All corresponding sections forming the lubricant supply element 50 have a plate-like shape. (First reference level, second reference level)

[0031] A plane encompassing the axis of rotation Ax of the worm gear 32 and the engagement section 34 is defined as the first datum plane P1. A plane encompassing the axis of rotation Ax and perpendicular to the first datum plane P1 is defined as the second datum plane P2. (First lubricant supply section, second lubricant supply section)

[0032] The lubricant supply element 50 comprises a first lubricant supply section 51 (lubricant supply section), which supplies lubricant to the engagement section 34 when the worm wheel 32 is rotated in a first direction (clockwise as indicated by arrow (1)), and a second lubricant supply section 52, which supplies lubricant to the engagement section 34 when the worm wheel 32 is rotated in a second direction (counterclockwise as indicated by arrow (2)) opposite to the first direction. The first lubricant supply section 51 is located on the right side (one side) of the first reference plane P1, and the second lubricant supply section 52 is located on the left side (the other side) of the first reference plane P1. (Storage section)

[0033] In relation to Fig. 4 and Fig. 5 the first lubricant supply section 51 comprises a bearing section 70 which supports an end section 61 of a lubricant receiving section 60 described later and is integrally formed with the lubricant receiving section 60.

[0034] The bearing section 70 overlaps an inner surface 42a of the cover 42 and is attached to it. Suitable fastening methods include known techniques such as gluing, screwing, or riveting. The element with which the bearing section 70 overlaps and to which it is attached is not limited to the cover 42, but can also be the container 41. Since the lubricant receiving section 60 is separate from the cover 42, it is supported exclusively by the bearing section 70. (End section of the lubricant absorption section)

[0035] Referring to Fig. 3A and Fig. 3B, for example, the end section 61 of the lubricant receiving section 60 extends essentially in the same direction as the axis of rotation Ax of the screw 31 extends when viewed along the direction of the axis of rotation Ax.

[0036] Of both ends 61a and 61b of the end section 61 of the lubricant receiving section 60, the end section closer to the axis of rotation Ax is defined as an inner end section 61a and the end section further away from the axis of rotation Ax is defined as an outer end section 61b. (Weakness section)

[0037] The end section 61 of the lubricant receiving section 60 is designed as a weak point section 51A, which is weaker than surrounding sections of the lubricant receiving section 60. For example, the thickness of the sheet material in the weak point section 51A is small, or a relief hole is formed in the weak point section 51A. The weak point section 51A can be designed in a suitable manner as long as it is located within the first lubricant supply section 51. (Shape of storage section 70)

[0038] Referring to Fig. 3B, the bearing section 70 has an overall ribbon-like shape and is designed such that an arc-shaped section 71 with its center in the axis of rotation Ax and a straight section 72, which extends from an end section of the arc-shaped section 71 in the direction of the worm 31, merge into one another.

[0039] The bearing section 70 can have any configuration as long as it has an overlapping surface 70a that overlaps with the inner surface 42a of the cover 42. The bearing section 70 intersects the second reference plane P2. The lubricant receiving section 60 is located closer to the screw 31 than the second reference plane P2. (Guide end section, end face section)

[0040] Referring to Fig. 4 and Fig. 5, the lubricant receiving section 60 comprises a guide end section 60a, which is closest to the engagement section 34, and a face-proximal section 62, one end of which is the guide end section 60a and which is provided in a straight line along the face 33 of the worm gear 32. A gap may be provided between the face-proximal section 62 and the face 33, or the face-proximal section 62 may be in contact with the face 33.

[0041] An end section of the section 62 near the end face, opposite the guide end section 60a, is defined as the opposite end section 62a. Referring to Fig. 3A is the opposite end section 62a arranged on an inner circumferential edge 33b of the annular end face 33. This means that the length of the section 62 near the end face corresponds to the entire width of the end face 33 of the worm gear 32.

[0042] Along the axis of rotation Ax (see Fig. 3A) Considered, the section 62 near the end face is inclined with respect to the first reference plane P1 (angle of inclination θ1). However, the section 62 near the end face can also overlap with the first reference plane P1 (angle of inclination θ1 = 0°). (Lubricant receiving element section)

[0043] Referring to Fig. 4 and Fig. 5. The lubricant receiving section 60 comprises a lubricant receiving element section 63, which includes the guide end section 60a and rests against the end face 33. The lubricant receiving element section 63 can directly receive lubricant adhering to the end face 33. The lubricant receiving element section 63 does not have to be perpendicular to the end face 33, but can also be inclined, as described below. The lubricant receiving element section 63 further comprises the following two sections, whose normal directions differ from each other. (Lower lubricant intake section)

[0044] The lubricant receiving element section 63 comprises a lower lubricant receiving section 64, which has a triangular geometry, of which both end sections 60a and 62a of the end-face-near section 62 and the inner end section 61a of the end section 61 of the lubricant receiving section 60 form vertices.

[0045] Referring to Fig. 6B, the lower lubricant intake section 64 is inclined inwards (in a direction towards the first reference plane P1) with respect to a direction perpendicular to the end face 33 of the worm gear 32 (see inclination angle θ2). However, the lower lubricant intake section 64 can also be inclined outwards (in a direction away from the first reference plane P1) or be oriented perpendicular to the end face 33 with respect to the direction perpendicular to the end face 33. (Upper lubricant intake section)

[0046] Referring to Fig. 4, above the lower lubricant receiving section 64, there is an upper lubricant receiving section 65 (inclined section) which has a triangular area comprising the guide end section 60a and the inner end section 61a. Referring to Fig. 5, is a vertex 66a, which together with the guide end section 60a and the inner end section 61a forms a triangle, is located above the guide end section 60a.

[0047] Referring to Fig. 6A, the upper lubricant intake section 65 is inclined relative to the direction perpendicular to the end face 33 of the worm gear 32 in a direction away from the first reference plane P1 (see inclination angle θ3). However, the upper lubricant intake section 65 can also be oriented perpendicular to the end face 33. A straight section connecting the vertex 66a with the guide end section 60a is defined as the upper tip region 66. The upper tip region 66, together with an upper tip region 86 described later, forms a V-shape (viewed from the engagement 34 in the direction of the axis of rotation Ax).

[0048] According to the embodiment described above (see inclination angles θ2 and θ3), the cross-section of the lubricant receiving element section 63 is curved such that it projects towards the first reference plane P1. However, the upper lubricant receiving section 65 and the lower lubricant receiving section 64 can also lie in a common plane. (Additional lubricant absorption section)

[0049] Referring to Fig. 4 and Fig. 5, an additional lubricant receiving section 67 is arranged above the upper lubricant receiving section 65. This additional receiving section has a surface facing the end face 33 without encompassing the guide end section 60a. The additional lubricant receiving section 67 can indirectly receive lubricant adhering to the end face 33. This means that the additional lubricant receiving section 67 is arranged to receive the lubricant received by the lubricant collecting element section 63.

[0050] The additional lubricant receiving section 67 has a surface that includes the apex 66a, the inner end section 61a, and the outer end section 61b. Referring to Fig. 3B, the additional lubricant receiving section 67 essentially has the shape of a parallelogram when viewed in a direction along the axis of rotation Ax. The additional lubricant receiving section 67 extends from the end section 61 of the lubricant receiving section 60 and is inclined towards the first reference plane P1 as it approaches the engagement section 34. Referring to Fig. 5, the additional lubricant intake section 67 is also inclined towards the front surface 33 as it gets closer to the engagement section 34. (Reception section rib)

[0051] Referring to Fig. 4 and Fig. 5, a lubricant receiving section rib 68 is formed on the lubricant receiving section 60, which extends over the lower lubricant receiving section 64, the upper lubricant receiving section 65 and the additional lubricant receiving section 67. The lubricant receiving section rib 68 runs substantially perpendicular to the end face 33 of the worm gear 32 and in a direction that is orthogonal to the first reference plane P1.

[0052] The receiving section rib 68 encompasses the opposite end section 62a of the section 62 near the end face. This allows the receiving section rib 68 to prevent movement of the lubricant, which is received by the lubricant receiving section 60, away from the engagement region 34. (Second lubricant supply section 52)

[0053] Referring to Fig. In Figure 3B, the second lubricant supply section 52 has a shape symmetrical to the first lubricant supply section 51 with respect to the first reference plane P1. The second lubricant supply section 52 comprises a bearing section 90 and a lubricant receiving section 80. The bearing section 70 comprises an arcuate section 91 and a straight section 92. The lubricant receiving section 50 comprises an end section 81, a lubricant collecting element section 83, an additional lubricant receiving section 87, a section near the end face 82, an opposing end section 82a, and an upper tip region 86.

[0054] The description of the components and other parts described above can be replaced, mutatis mutandis, by the description of the components of the first lubricant supply section 51. A detailed description of the components of the second lubricant supply section 52 is therefore omitted.

[0055] An end section 70b (an end section opposite the section that supports the end section 61 of the lubricant receiving section 60) of the bearing section 70 of the first lubricant supply section 51 and an end section 90b (an end section opposite the section that supports the end section 81 of the lubricant receiving section 80) of the bearing section 90 of the second lubricant supply section 52 overlap with the first reference plane P1. This means that the bearing section 70 and the bearing section 90 are designed to be conjoined. (Connecting section)

[0056] Referring to Fig. 3B and Fig. 4. The end-face-adjacent section 62 of the first lubricant supply section 51 and the end-face-adjacent section 82 of the second lubricant supply section 52 are integrally connected by a connecting section 53. The connecting section 53 is a triangular element whose vertices are the guide end section 60a, the opposite end section 62a of the end-face-adjacent section 62, and the opposite end section 82a of the end-face-adjacent section 82. The lubricant receiving section 60 and the lubricant receiving section 80 form a V-shape when viewed along the axis of rotation Ax.

[0057] Referring to Fig. 6B, the connecting section 53 comprises an facing surface 53a, which faces the end face 33 of the worm gear 32. A gap may be present between the facing surface 53a and the end face 33, or the facing surface 53a and the end face 33 may be in contact with each other. (First effect)

[0058] Referring to Fig. 7. During operation of the worm gear mechanism 30, high-viscosity lubricant G inevitably adheres to the end face 33 of the worm wheel 32. The worm gear mechanism 30 comprises the first lubricant supply section 51, which can supply the lubricant G adhering to the end face 33 of the worm wheel 32 to the engagement section 34. If the worm wheel 32 is rotated clockwise, the lubricant G adhering to the end face 33 of the worm wheel 32 also moves in the direction of rotation, as indicated by arrow (3).

[0059] The first lubricant supply section 51 comprises the lubricant receiving section 60, which is provided in a position that allows the lubricant receiving section 60 to come into contact with and receive the lubricant G moving with the end face 33.

[0060] Referring to Fig. 4 and Fig. 5 The lubricant receiving section 60 comprises a lubricant receiving element section 63, which is arranged such that it rests against the end face 33. The moving lubricant comes into contact with the lubricant receiving element section 63 and is collected on the lubricant receiving element section 63.

[0061] Since the lubricant receiving element section 63 includes the guide end section 60a, the lubricant collected at the lubricant receiving element section 63 is supplied to the engagement section 34, as indicated by an arrow (4) in Fig. Figure 7 shows that the worm gear mechanism 30 can be provided accordingly, which maintains a lubrication condition with the lubricant G. (Second Effect)

[0062] Referring to Fig. 4 and Fig. 5, the first lubricant supply section 51 is designed such that the lubricant receiving section 60 and the bearing section 70 are integrally formed together. The bearing section 70 overlaps with and is attached to the inner surface 42a of the cover 42 of the housing 40; and the bearing section 70 itself is firmly connected to the cover 42.

[0063] On the other hand, the end section 61 of the lubricant intake section 60 is supported by the bearing section 70, and the lubricant intake section 60 is further separated from the cover 42. If the first lubricant supply section 51 comes into contact with the worm gear 31 due to excessive thermal deformation or an external load acting on the cover 42, a load is exerted on the first lubricant supply section 51. If such a load is exerted on the first lubricant supply section 51, the load is concentrated on the end section 61 of the lubricant intake section 60. The first lubricant supply section 51 can be easily separated into the bearing section 70 and the lubricant intake section 60, with the end section 61 of the lubricant intake section 60 forming the boundary. The first lubricant supply section 51 does not break into small pieces, thus preventing small pieces from being caught by the worm gear 31. (Third effect)

[0064] Referring to Fig. 2, carrying out assembly work to attach the first lubricant supply section 51 is simpler compared to a case in which the bearing section 70 would be attached to the container 41, for example, because the bearing section 70 is attached to the inner surface 42a of the lid 42. (Fourth Effect)

[0065] Referring to Fig. 3A and Fig. 5, the end-face section 62, viewed along the axis of rotation Ax, is inclined with respect to the first reference plane P1 (inclination angle θ1). Since the lubricant, which is moved when the end face 33 of the worm gear 32 is rotated, comes into contact with the lubricant receiving element section 63 at an angle, the lubricant is easily guided to the engagement section 34. The end-face section 62 can also be arranged to overlap the first reference plane P1. (Fifth Effect)

[0066] Referring to Fig. 6A, the upper lubricant intake section 65 (inclined section) is inclined in a direction away from the first reference plane P1, relative to a direction perpendicular to the end face 33 of the screw 31 (incline angle θ3). This prevents lubricant splashing when the lubricant is captured by the lubricant intake section 60. (Sixth Effect)

[0067] Referring to Fig. 4. The first lubricant supply section 51 includes a weak point section 51A, which is weaker than the surrounding sections of the lubricant receiving section 60. Since the weak point section 51A is provided in advance, the lubricant receiving section 60 can easily be separated into two parts when the first lubricant supply section 51 is subjected to a load at the weak point section 51A as its boundary. This prevents separated parts from getting caught between the worm gear 32 and the worm 31. (Seventh Effect)

[0068] The weak point section 51A is provided at the end section 61 of the lubricant intake section 60. Therefore, the first lubricant intake section 60 can be easily separated into the lubricant intake section 60 and the bearing section 70. This prevents the lubricant intake section 60 from getting between the worm gear 32 and the worm 31. (Eighth effect)

[0069] Referring to Fig. 7, the lubricant supply element 50 comprises, in addition to the first lubricant supply section 51, the second lubricant supply section 52. The second lubricant supply section 52 comprises the second lubricant receiving section 60.

[0070] When the worm wheel 32 is rotated counterclockwise (see arrow (2)), the second lubricant supply section 52 can supply the lubricant adhering to the end face 33 of the worm wheel 32 to the engagement section 34.

[0071] In a worm gear mechanism in which the worm wheel 32 is rotated either only clockwise or counterclockwise, it is sufficient if, according to the direction of rotation of the worm wheel 32, only one of the first lubricant supply section 51 and the second lubricant supply section 52 is provided.

[0072] In the worm gear mechanism 30 of the electric power steering device 10, the worm wheel 32 is rotated both clockwise and counterclockwise. In this case, the lubricant supply element 50 is provided with both the first lubricant supply section 51 and the second lubricant supply section 52, so that lubricant can be supplied to the engagement section 34 regardless of the direction of rotation of the worm wheel 32. (Ninth Effect)

[0073] The second lubricant supply section 52 has a shape symmetrical to that of the first lubricant supply section 51 with respect to the first reference plane P1. This allows lubricant to be supplied uniformly to the engagement section 34, regardless of the direction of rotation of the worm gear 32. Alternatively, the second lubricant supply section 52 can be designed asymmetrically to the first lubricant supply section 51. (Tenth Act)

[0074] The end section 70b of the bearing section 70 of the first lubricant supply section 51 and the end section 90b of the mounting section 90 of the second lubricant supply section 52 are continuous. Furthermore, the end-face section 62 of the second lubricant supply section 52 is continuous with the end-face section 62 of the first lubricant supply section 51 via the connecting section 53. This means that the first lubricant supply section 51 and the second lubricant supply section 52 are integrally formed to create the lubricant supply element 50. The strength of the lubricant supply element 50 is increased. The lubricant supply element 50 has an annular shape that surrounds the axis of rotation Ax. (Eleventh Effect)

[0075] The electric power steering device 10 comprises the worm 31, which is rotated by a drive force generated by the electric motor 33, a worm wheel 32, which engages with the worm 31 and transmits the drive force of the electric motor 33 to the steering rack, and the lubricant supply section 50, which can supply lubricant adhering to the end face 33 of the worm wheel 32 to the engagement section 34, wherein a section is defined as engagement section 34 in which the worm wheel 32 and the worm 31 engage most deeply with each other when the end face 33 of the worm wheel 32 is viewed in a direction along the axis of rotation Ax of the worm wheel 32.

[0076] The lubricant supply section 50 comprises the lubricant receiving section 60, which is positioned to allow it to come into contact with the lubricant adhering to the end face 33 of the worm gear and to receive the lubricant during the rotation of the worm gear 32. The receiving section then supplies the received lubricant to the engagement section 34. This enables the electric power steering device 10 to be equipped with the worm gear mechanism 30, which maintains lubrication through the lubricant. Since the worm gear 30 used in the electric power steering device 10 is located in a thermally stressed environment, there is a high demand for the worm gear mechanism 30 to maintain lubrication through the lubricant.

[0077] The invention is not limited to these embodiments, provided the functions and effects of the invention are achieved. In particular, the design of the lubricant intake section 60, which extends from the section 62 near the end face to beyond the end section 61, can be adapted as desired, as long as the lubricant intake section 60 is arranged in contact with the end face 33 of the worm gear 32 in order to receive lubricant and supply it to the engagement section 34. The top, bottom, left side, and right side are used to describe the worm gear mechanism 30 simply and do not restrict any direction when the worm gear mechanism 30 is operated. The worm gear mechanism 30 is not limited to a worm gear mechanism provided in the electric power steering 10, and the drive source of the worm 31 can also be freely selected. EXPLANATION OF LETTERS OR NUMBERS 10 Electric power steering device 14 Electric motor 30 worm gear mechanism 31 snail 32 worm gear 32a Wave section 33 Front surface 33a outer circumferential edge 33b inner circumferential margin 34 Intervention section 40 cases 41 containers 41a Opening 42 lids 50 Lubricant supply element 51 First lubricant supply section (lubricant supply section) 52 second lubricant supply section 60 Lubricant intake section 60a Guide end section 61 End section of the lubricant intake section 62 Section near the front face 63 Lubricant receiving element section 65 upper lubricant intake section (inclined section) Axis: axis of rotation of the worm gear P1 first reference plane (reference plane) QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2009-248724

[0005]

Claims

[1] Worm gear mechanism, comprising: a worm that is rotated by a driving force generated by a power source; a worm gear that engages with the worm; and a lubricant supply section configured to supply lubricant adhering to an end face of the worm wheel to an engagement section, wherein a section is defined as the engagement section in which the worm wheel and the worm engage most deeply with each other when the end face of the worm wheel is viewed in a direction along an axis of rotation of the worm wheel, wherein the lubricant supply section comprises a lubricant receiving section which is provided in a position which enables the lubricant receiving section to come into contact with the lubricant adhering to the end face of the worm wheel and to receive the lubricant during the rotation of the worm wheel, and which supplies the received lubricant to the engagement section. [2] Worm gear mechanism according to claim 1, further comprising: a housing that accommodates the worm and the worm wheel, wherein the lubricant supply section comprises a bearing section which supports an end section of the lubricant receiving section and which is integrally formed with the lubricant receiving section, and the bearing section overlaps the housing and is attached to it. [3] Worm gear mechanism according to claim 2, wherein the housing comprises a container in which an opening is formed and a lid which closes the opening, and wherein the bearing section is attached to the lid. [4] Worm gear mechanism according to claim 1, wherein the lubricant receiving section comprises a guide end section closest to the engagement section and an end-face section provided by the guide end section along a straight line along the end face of the worm wheel, wherein a plane comprising the axis of rotation of the worm wheel and the engagement section is defined as the reference plane, and wherein the end-face section is arranged such that it is inclined in a direction along the axis of rotation of the worm wheel with respect to the reference plane. [5] Worm gear mechanism according to claim 1, wherein the lubricant receiving section comprises a lubricant receiving element section which includes a guide end section nearest to the engagement section and is arranged such that it rests against the end face of the worm gear, wherein a plane comprising the axis of rotation of the worm gear and the engagement section is defined as the reference plane, and wherein the lubricant receiving element section comprises an inclined section which is arranged such that it is inclined in a direction away from the reference plane with respect to a direction perpendicular to the end face of the worm gear. [6] Worm gear mechanism according to any one of claims 1 to 5, wherein the lubricant supply section comprises a weak point section which is weaker than surrounding sections of the lubricant supply section. [7] Worm gear mechanism according to claim 6, wherein the weak point section is provided at an end section of the lubricant receiving section or in the lubricant receiving section. [8] Worm gear mechanism according to claim 1, further comprising: a second lubricant supply section, which is provided in a position that allows the second lubricant supply section to come into contact with the lubricant adhering to the face of the worm wheel and to absorb the lubricant during the rotation of the worm wheel, and which supplies the absorbed lubricant to the engagement section, where a plane comprising the axis of rotation of the worm gear and the engagement section is defined as the reference plane, wherein the lubricant supply section is arranged on one side of the reference plane, and wherein the second lubricant supply section is located on the other side of the reference plane. [9] Worm gear mechanism according to claim 8, wherein the second lubricant supply section has a shape symmetrical with respect to the reference plane to the lubricant supply section. [10] Worm gear mechanism according to claim 9, wherein the lubricant supply section and the second lubricant supply section are integrally formed together and form an annular shape to surround the axis of rotation when viewed in the direction along the axis of rotation of the worm wheel. [11] Electric power steering system comprising: a snail that is rotated by a driving force generated by an electric motor; a worm gear that engages with the worm and transmits the driving force of the electric motor to a steering rack; and a lubricant supply section configured to supply lubricant adhering to an end face of the worm wheel to a meshing section, wherein a section is defined as the meshing section where the worm wheel and the worm engage most deeply with each other when the end face of the worm wheel is viewed in a direction along an axis of rotation of the worm wheel, wherein the lubricant supply section comprises a lubricant receiving section which is provided in a position which enables the lubricant receiving section to come into contact with the lubricant adhering to the end face of the worm wheel and to receive the lubricant during the rotation of the worm wheel, and which supplies the received lubricant to the engagement section.

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