JP2017128210A - Gear for steering device, and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the abrasion and breakage of teeth flanks when the teeth of a gear that transmits the power generated by a power generating part are formed of resin in a vehicle steering device.SOLUTION: A first worm wheel (223) has a tooth part (223a) obtained by molding a polyamide resin composition predominantly composed of polyamide resin, the polyamide resin having a viscosity number of 190 ml/g or more.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a steering gear and a steering device.

  In a vehicle steering apparatus including a power generation unit such as an electric power steering apparatus, the power generated by the power generation unit is transmitted to a steering shaft or the like via, for example, a worm gear and a worm wheel. At this time, in order to suppress rattling noise and the like, it is known that the teeth of the worm wheel are formed of resin (for example, Patent Documents 1 and 2).

JP 2013-155788 A JP2015-127162A

  By the way, in a vehicle steering apparatus, a large load is applied to a gear that transmits power generated by a power generation unit. Therefore, when the gear teeth are formed of resin, it is preferable to reduce wear and damage on the tooth surfaces.

  An object of the present invention is to reduce wear and breakage of a tooth surface when a tooth of a gear that transmits power generated by a power generation unit is formed of resin in a vehicle steering apparatus.

  For this purpose, the present invention provides a steering gear that is connected to a power generation unit of a vehicle steering device so that torque can be transmitted, by molding a polyamide resin composition containing polyamide resin as a main component. The polyamide resin has a viscosity number of 190 ml / g or more.

  By setting it as such a structure, the abrasion and damage of a tooth surface can be reduced.

  In addition, for this purpose, the present invention provides a steering apparatus for a vehicle, comprising: a power generation section; and a steering apparatus gear connected to the power generation section so as to be able to transmit torque. Comprises a tooth part formed by molding a polyamide resin composition containing a polyamide resin as a main component, and the viscosity number of the polyamide resin is 190 ml / g or more.

  ADVANTAGE OF THE INVENTION According to this invention, when the tooth | gear of the gear which transmits the motive power which the motive power generation part generated is formed with resin in the steering apparatus of a vehicle, abrasion and damage of a tooth surface can be reduced.

It is a mimetic diagram showing typically the schematic structure of the steering device concerning Embodiment 1 of the present invention. It is a schematic diagram which shows typically the partial structure of the 1st assist force generator in the steering device which concerns on Embodiment 1 of this invention. (A) is a perspective view of the 1st worm wheel concerning Embodiment 1 of the present invention, and (b) is a sectional view of the 1st worm wheel concerning Embodiment 1 of the present invention. It is a schematic diagram which shows typically schematic structure of the steering device which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows typically schematic structure of the steering device which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows typically schematic structure of the steering device which concerns on Embodiment 4 of this invention. It is a graph which shows the result of a durability test.

  The present invention is a gear for a steering device that is connected so as to be able to transmit torque to a power generation unit provided in a steering device of a vehicle, and is formed by molding a polyamide resin composition containing polyamide resin (PA) as a main component. There is provided a gear for a steering device (hereinafter referred to as “steering device gear according to the present invention”) having tooth portions and having a viscosity number of 190 ml / g or more of the polyamide resin. The “steering device gear” refers to a gear used in the steering device.

  “Vehicle steering device” refers to a device provided in a vehicle and having a function of turning wheels according to a steering operation by a driver. The “power generation unit included in the vehicle steering device” refers to a prime mover such as a motor that generates power used in the steering device. Examples of power used in the steering device include assist force in an electric power steering device, reaction force or steering force in a steer-by-wire type steering device, and the like.

  “Connecting so that torque can be transmitted” means that the other member rotates so as to rotate as one member rotates. For example, one member and the other member are integrally formed. If the other member is fixed directly or indirectly to one member, and one member and the other member are connected to each other via a joint member or the like Including at least cases.

  In the present specification, the “main component” refers to a component having a higher content in the composition than other components. "Composition" refers to a substance that contains one or more components. “Made of the polyamide resin composition” means that the polyamide resin composition is molded into a desired shape. The “tooth portion” refers to a portion including a tooth in the gear. “Viscosity number” refers to the viscosity number measured according to JIS K6933: 2013.

  Since the gear for a steering device according to the present invention is connected to the power generation unit so that torque can be transmitted, a large load is applied to the tooth portion. However, the tooth portion provided in the steering gear according to the present invention is formed by molding a polyamide resin composition having a viscosity number of 190 ml / g or more, and thus has high fatigue strength and reduces tooth surface wear and damage. can do.

  In particular, when it is required to increase the output of the power generation unit in order to increase the thrust of the rack bar, a larger load is applied to the gear connected to the power generation unit so as to transmit torque. The gear for a steering device according to the present invention can be suitably used under such conditions that require high durability. As shown in the examples described later, the steering gear according to the present invention is more effective in reducing tooth surface wear and damage as the load increases. For example, the steering gear according to the present invention can be particularly preferably used under the condition that the maximum value of the torque transmitted from the power generation unit is 63.7 Nm or more.

  In addition, the gear for a steering device according to the present invention includes a tooth portion formed by molding a polyamide resin composition, so that it is possible to reduce rattling noise and to obtain good oil resistance and heat resistance. it can.

  In one embodiment, the viscosity number of the polyamide resin may be 190 ml / g or more, and for example, 200 ml / g or more and 210 ml / g or more is more preferable. The upper limit of the viscosity number of the polyamide resin is not particularly limited, and can be selected in consideration of moldability and the like.

  Since the polyamide resin having a viscosity number in such a range has a large molecular weight, it is possible to improve the fatigue strength of teeth formed by a polyamide resin composition containing the polyamide resin as a main component. Thereby, abrasion and damage of a tooth surface can be reduced suitably.

  In one embodiment, the tensile yield elongation of the polyamide resin composition is not particularly limited, but is preferably 6% or more, more preferably 8% or more, 10% or more, or 12% or more. .

  Teeth formed with a polyamide resin composition having a viscosity number of 190 ml / g or more and a tensile yield elongation of the polyamide resin composition of 6% or more are molecules between the resins in the resin composition when a large load is applied. Therefore, the contact area between the teeth can be increased by being deformed so as to follow the shape of the teeth of the counterpart gear. In particular, when the contact between the teeth in the initial state is almost a line contact, such as meshing between the worm gear and the worm wheel, the contact area can be increased more suitably. And by increasing the contact area between teeth, the surface pressure concerning a tooth surface can be reduced and wear and breakage of a tooth surface can be reduced suitably.

  In one embodiment, 23 ° C. 50% R.D. H. Although the equilibrium water absorption of the polyamide resin composition in is not particularly limited, it is more preferably 3.0% or less.

  Teeth formed from a polyamide resin composition having a water absorption rate in such a range can suppress expansion due to water absorption.

  In one embodiment, the type of polyamide resin is not particularly limited, and may be appropriately selected so as to satisfy the above-described conditions. For example, a nylon resin such as polyamide 410, polyamide 66, or polyamide 46 is preferably used. Can do. The polyamide resin may be composed of only one type of polyamide resin, or may be a mixture of a plurality of types of polyamide resins.

  In one embodiment, a suitable polyamide resin includes, for example, polyamide 410. For example, the polyamide 410 has good characteristics such as a larger tensile yield elongation and a lower water absorption than the polyamide 66. Among them, polyamide 410 “EcoPaXX Q210E-H” (DSM) has a viscosity number of 210 ml / g, and can be particularly preferably used as a material for a gear for a steering device according to the present invention.

  In one embodiment, the content of the polyamide resin in the polyamide resin composition is, for example, preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. preferable.

  In one embodiment, the polyamide resin composition is a resin other than a polyamide resin, for example, polyacetal (POM), polycarbonate (PC), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyarylate (PAR), Polyamideimide (PAI), polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) and the like may be contained. Although content of resin other than the polyamide resin in a polyamide resin composition is not specifically limited, For example, it can be set as the range of 0 to 40 mass%.

  In one embodiment, the polyamide resin composition may contain an additive. Examples of the additive include reinforcing fibers, fillers, plasticizers, colorants, stabilizers, mold release agents, flame retardants, auxiliaries, and the like. Although content of the additive in a polyamide resin composition is not specifically limited, For example, it can be set as the range of 0 to 40 mass%.

  In addition, as a reinforced fiber, an aramid fiber, glass fiber, carbon fiber etc. can be used, for example. Wear resistance can be improved by including reinforcing fibers in the range of 5% by mass or more and 30% by mass or less with respect to the polyamide resin composition, but on the other hand, tensile yield elongation may be deteriorated. is there. Therefore, in one embodiment, the polyamide resin composition does not contain reinforcing fibers, or even if it contains reinforcing fibers, the content of reinforcing fibers is preferably less than 15% by mass, and less than 5% by mass. More preferably. Thereby, since the tensile yield elongation of a tooth part is securable, as mentioned above, the surface pressure concerning a tooth surface can be reduced and wear and damage of a tooth surface can be reduced suitably.

  In one embodiment, the steering gear according to the present invention can be manufactured by molding a polyamide resin composition into a gear shape as described later. The entire steering gear may be formed by integrally molding a polyamide resin composition, or the steering gear may be composed of a tooth portion and a central portion that supports the tooth portion. Then, the tooth portion may be produced by molding a polyamide resin composition. For example, a central portion of the steering gear may be formed of metal, but is not limited thereto.

  In one embodiment, the steering gear according to the present invention may be a gear provided in a path for transmitting power from the power generation unit to the steered shaft or the steering member, and particularly constitutes a reduction gear. A gear is preferred. The gear for a steering device according to the present invention can be suitably used as a gear for a speed reducer to which a high load is applied.

  In one embodiment, the steering gear according to the present invention may be an external gear, an internal gear, or a bevel gear. In one embodiment, the gear for a steering device according to the present invention may be a spur gear or an inclined gear. In one embodiment, the steering gear according to the present invention may be a worm wheel, a planetary gear, a sun gear, or a ring gear.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
First, a steering apparatus 1 according to Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic diagram schematically illustrating an example of a schematic configuration of the steering device 1. As shown in FIG. 1, the steering apparatus 1 includes a steering member 200, a first steering shaft 101, a first universal joint 201, an intermediate shaft 104, a second universal joint 202, a first pinion shaft 105, a second Pinion shaft 106, first torque sensor 107, first pinion gear 210, rack bar (steering shaft) 211, tie rod 212, knuckle arm 213, first power generation unit (power generation unit) 220, first A power transmission shaft 221, a first worm gear 222, a first worm wheel (steering device gear) 223, a second power transmission shaft 224, a second pinion gear 225, a controller 300 and wheels 400 are provided.

  The steering device 1 transmits the assist force generated by the first power generation unit 220 to the rack bar 211 via the first worm gear 222, the first worm wheel 223, and the second pinion gear 225. This is an assist (DPA) type electric power steering device. In the present embodiment, the first worm wheel 223 is the steering gear according to the present invention.

  The steering member 200 is a member that is steered by the driver. As the steering member 200, as shown in FIG. 1, a steering wheel having a wheel shape is taken as an example. However, this is not a limitation of the present embodiment, and any steering member 200 can accept a steering operation by a driver. It may have other shapes and mechanisms.

  The steering member 200, the first steering shaft 101, the intermediate shaft 104, the first pinion shaft 105, the second pinion shaft 106, and the first pinion gear 210 are connected to each other so as to be able to transmit torque.

  In the present embodiment, the upper end of the first steering shaft 101 is fixed to the steering member 200 and rotates integrally with the steering member 200. The lower end of the first steering shaft 101 and the upper end of the intermediate shaft 104 are connected to each other via the first universal joint 201. Further, the lower end of the intermediate shaft 104 and the upper end of the first pinion shaft 105 are connected to each other via the second universal joint 202.

  The “upper end” refers to the upstream end (that is, the input end) in the steering force transmission path corresponding to the driver's steering operation, and the “lower end” refers to the steering force. It refers to the downstream end (that is, the output end) in the transmission path (the same applies hereinafter).

  Further, the first pinion shaft 105 and the second pinion shaft 106 are elastically connected to each other so that torque can be transmitted, and the torsion generated between the first pinion shaft 105 and the second pinion shaft 106 is the first. 1 is detected by the torque sensor 107. Details will be described later.

  The first pinion gear 210 is fixed to the lower end of the second pinion shaft 106 and rotates integrally with the second pinion shaft 106. The rack bar 211 is configured to steer the wheel 400 according to the rotation of the first pinion gear 210, and rack teeth that mesh with the first pinion gear 210 are formed on the rack bar 211.

  In the steering device 1 configured as described above, when the driver performs a steering operation via the steering member 200, the first pinion gear 210 rotates, and the rack bar 211 moves along the axial direction of the rack bar 211. Displace. As a result, the wheel 400 is steered via the tie rod 212 provided at both ends of the rack bar 211 and the knuckle arm 213 connected to the tie rod 212.

(First assist force generator 10)
Next, the first assist force generator 10 having a function of generating an assist force and transmitting the assist force to the rack bar 211 will be described. FIG. 2 is a schematic diagram schematically showing a partial structure of the first assist force generator 10.

  In the present embodiment, the first assist force generator 10 includes a first torque sensor 107, a first power generation unit 220, a first power transmission shaft 221, a first worm gear 222, and a first worm wheel 223. The second power transmission shaft 224 and the second pinion gear 225 are configured.

The first torque sensor 107 detects torsion that occurs between the first pinion shaft 105 and the second pinion shaft 106. More specifically, a cavity is formed inside the first pinion shaft 105 and the second pinion shaft 106, and the first pinion shaft 105 and the second pinion shaft 106 are placed in the cavity. A torsion bar for elastic connection is arranged. When the driver performs a steering operation via the steering member 200, a torsion angle θ _T corresponding to the magnitude of the steering operation torque _T is generated between the first pinion shaft 105 and the second pinion shaft 106. . The first torque sensor 107 detects the twist angle θ _T and supplies a torque sensor signal SL107 indicating the detection result to the control unit 300.

  The first power generation unit 220 applies torque to the first power transmission shaft 221 and the first worm gear 222 in accordance with the torque control signal SL220 supplied from the control unit 300. The first power generation unit 220 is, for example, a motor body. The first worm gear 222 is connected to the first power transmission shaft 221 so as to be able to transmit torque. For example, the first worm gear 222 rotates integrally with the first power transmission shaft 221. Thereby, the first worm gear 222 is rotationally driven by the first power generation unit 220. If a general-purpose electric motor is used as the first power generation unit 220, the manufacturing cost can be further suppressed.

  The first worm wheel 223 meshes with the first worm gear 222, and torque is transmitted from the first worm gear 222. The gear ratio is preferably adjusted so that the combination of the first worm gear 222 and the first worm wheel 223 functions as a reduction gear for rotation generated by the first power generation unit 220.

  The first worm wheel 223 is connected to the second pinion gear 225 via the second power transmission shaft 224 so that torque can be transmitted. For example, the first worm wheel 223 includes the second power transmission shaft 224 and the second pinion gear 225. It is designed to rotate together. As a result, the torque generated by the first power generation unit 220 is transmitted to the second pinion gear 225.

  Rack teeth 211 a provided on the rack bar 211 are meshed with the second pinion gear 225, and a thrust can be applied to the rack bar 211 as the second pinion gear 225 rotates.

  As shown in FIG. 2, the first worm gear 222, the first worm wheel 223, the second power transmission shaft 224, and the second pinion gear 225 are accommodated in a housing 226, and the second pinion gear The rack bar 211 is urged against the second pinion gear 225 by the urging member 228 so that the rack teeth 211 a mesh with the 225.

  The control unit 300 controls the assist force generated by the first power generation unit 220 in accordance with the steering operation by the driver. In FIG. 1, the control unit 300 is disposed at a position different from that of the first assist force generation device 10, but the control unit 300 may be disposed in the first assist force generation device 10.

  The controller 300 refers to the torque sensor signal SL107 supplied from the first torque sensor 107, generates a torque control signal SL220 for controlling the assist force generated by the first power generator 220, and 1 to the power generation unit 220. The control unit 300 may be configured to generate the torque control signal SL220 by further referring to a signal indicating the steering angle of the steering member 200, a vehicle speed signal from a vehicle speed sensor, and the like.

(First worm wheel 223)
Then, the 1st worm wheel 223 which is a gear for steering devices concerning the present invention is explained. FIG. 3A is a perspective view of the first worm wheel 223, and FIG. 3B is a cross-sectional view of the first worm wheel 223.

  As shown in FIG. 3, the first worm wheel 223 includes a tooth portion 223 a in which oblique teeth are carved and a central portion 223 b that supports the tooth portion 223 a. The tooth part 223a is formed by molding a polyamide resin composition containing a polyamide resin as a main component. The conditions to be satisfied by the polyamide resin and the polyamide resin composition are the same as those of the gear for a steering device according to the present invention, and thus the description thereof is omitted. The central part 223b is made of metal. However, the entire first worm wheel 223 may be formed from a polyamide resin composition.

  The first worm wheel 223 is a gear that is connected to the first power generation unit 220 so as to be able to transmit torque. More specifically, the first worm wheel 223 is a first driven to rotate by the first power generation unit 220. The gear meshes with the worm gear 222. The first worm wheel 223 is integrated with a second pinion gear that meshes with rack teeth provided on the rack bar 211 at a position different from the first pinion gear 210 connected to the steering member 200 so as to be able to transmit torque. Rotate. Such a first worm wheel 223 is subjected to a larger load than the steering gear for other configurations (for example, the second worm wheel 16 in the second embodiment), but the first worm wheel 223 has a large load. Since this is the gear for a steering device according to the present invention, it can be suitably used under conditions where high durability is required.

[Embodiment 2]
A steering apparatus 2 according to Embodiment 2 of the present invention will be described with reference to FIG. The members already described in this specification are denoted by the same reference numerals, and the description thereof is omitted below.

  As shown in FIG. 4, the steering device 2 includes a second assist force generation device 20 instead of the first assist force generation device 10 in the steering device 1. The second assist force generator 20 includes a second torque sensor 12, a second power generator 13, a third power transmission shaft 14, a second worm gear 15, and a second worm wheel 16. .

  In the steering device 2, the lower end of the first steering shaft 101 is elastically connected to the upper end of the second steering shaft 102 so that torque can be transmitted, and the lower end of the second steering shaft 102 is intermediate. The upper end of the shaft 104 is connected to each other via the first universal joint 201. The first pinion gear 210 is fixed to the lower end of the first pinion shaft 105 and rotates integrally with the first pinion shaft 105. There is no second pinion shaft 106.

  The steering device 2 transmits the assist force generated by the second power generation unit 13 to the second steering shaft 102 via the second worm gear 15 and the second worm wheel 16. It is a steering device. In the present embodiment, the second worm wheel 16 is a steering gear according to the present invention.

  Similar to the first torque sensor 107, the second torque sensor 12 detects torsion occurring between the first steering shaft 101 and the second steering shaft 102, and generates a torque sensor signal SL12 indicating the detection result. It supplies to the control part 300.

  The second power generation unit 13 gives torque to the third power transmission shaft 14 in accordance with the torque control signal SL13 supplied from the control unit 300. The second worm gear 15 is connected to the third power transmission shaft 14 so as to be able to transmit torque. For example, the second worm gear 15 rotates integrally with the third power transmission shaft 14. Thereby, the second worm gear 15 is rotationally driven by the second power generation unit 13.

  The second worm wheel 16 meshes with the second worm gear 15, and torque is transmitted from the second worm gear 15. The combination of the second worm gear 15 and the second worm wheel 16 is preferably adjusted in gear ratio so as to function as a reduction gear for rotation generated by the second power generation unit 13.

  The second worm wheel 16 is connected to the second steering shaft 102 so as to be able to transmit torque. For example, the second worm wheel 16 rotates integrally with the second steering shaft 102. As a result, the torque generated by the second power generation unit 13 is transmitted to the second steering shaft 102.

  The controller 300 controls the assist force generated by the second power generator 13 in accordance with the steering operation by the driver. In FIG. 4, the control unit 300 is disposed at a position different from that of the second assist force generation device 20, but the control unit 300 may be disposed in the second assist force generation device 20.

  The controller 300 refers to the torque sensor signal SL12 supplied from the second torque sensor 12, generates a torque control signal SL13 for controlling the assist force generated by the second power generator 13, and 2 is supplied to the power generation unit 13. The control unit 300 may be configured to generate the torque control signal SL13 by further referring to a signal indicating the steering angle of the steering member 200, a vehicle speed signal from a vehicle speed sensor, and the like.

(Second worm wheel 16)
Then, the 2nd worm wheel 16 which is a gear for steering devices concerning the present invention is explained. Like the 1st worm wheel 223 shown in FIG. 3, the 2nd worm wheel 16 is comprised from the tooth | gear part by which the oblique tooth was carved, and the center part which supports a tooth | gear part. The tooth portion is formed by molding a polyamide resin composition containing a polyamide resin as a main component. The conditions to be satisfied by the polyamide resin and the polyamide resin composition are the same as those of the gear for a steering device according to the present invention, and thus the description thereof is omitted. The central part is made of metal. However, you may form the whole 2nd worm wheel 16 from a polyamide resin composition.

  The second worm wheel 16 is a gear connected to the second power generation unit 13 so as to be able to transmit torque. More specifically, the second worm wheel 16 is rotated by the second power generation unit 13. The gear meshes with the worm gear 15. The second worm wheel 16 rotates integrally with the second steering shaft 102 connected to the steering member 200 so as to be able to transmit torque. The steering gear according to the present invention can also be suitably applied to such second worm wheel 16.

[Embodiment 3]
A steering apparatus 3 according to Embodiment 3 of the present invention will be described with reference to FIG. The members already described in this specification are denoted by the same reference numerals, and the description thereof is omitted below.

  As shown in FIG. 5, the steering device 3 includes a third assist force generating device 30 instead of the first assist force generating device 10 in the steering device 1. The third assist force generator 30 includes a first torque sensor 107, a third power generation unit 110, a fourth power transmission shaft 111, a third worm gear 112, and a third worm wheel 113. .

  The steering device 3 transmits the assist force generated by the third power generation unit 110 to the first pinion shaft 105 via the third worm gear 112 and the third worm wheel 113, and the pinion assist type electric power. It is a steering device. In the present embodiment, the third worm wheel 113 is the steering gear according to the present invention.

  The third power generation unit 110 gives torque to the fourth power transmission shaft 111 in accordance with the torque control signal SL110 supplied from the control unit 300. The third worm gear 112 is connected to the fourth power transmission shaft 111 so as to be able to transmit torque. For example, the third worm gear 112 rotates integrally with the fourth power transmission shaft 111. As a result, the third worm gear 112 is rotationally driven by the third power generation unit 110.

  The third worm wheel 113 meshes with the third worm gear 112, and torque is transmitted from the third worm gear 112. The gear ratio is preferably adjusted so that the combination of the third worm gear 112 and the third worm wheel 113 functions as a reduction gear for rotation generated by the third power generation unit 110.

  The third worm wheel 113 is connected to the first pinion shaft 105 so as to be able to transmit torque. For example, the third worm wheel 113 rotates integrally with the first pinion shaft 105. Thereby, the torque generated by the third power generation unit 110 is transmitted to the first pinion shaft 105.

  The control unit 300 controls the assist force generated by the third power generation unit 110 in accordance with the steering operation by the driver. In FIG. 5, the control unit 300 is disposed at a position different from that of the third assist force generation device 30, but the control unit 300 may be disposed in the third assist force generation device 30.

  The controller 300 refers to the torque sensor signal SL107 supplied from the first torque sensor 107, generates a torque control signal SL110 for controlling the assist force generated by the third power generator 110, and 3 is supplied to the power generation unit 110. The control unit 300 may be configured to generate the torque control signal SL110 by further referring to a signal indicating the steering angle of the steering member 200, a vehicle speed signal from a vehicle speed sensor, and the like.

(Third worm wheel 113)
Next, the third worm wheel 113 that is a gear for a steering device according to the present invention will be described. Like the 1st worm wheel 223 shown in FIG. 3, the 3rd worm wheel 113 is comprised from the tooth | gear part by which the oblique tooth was carved, and the center part which supports a tooth | gear part. The tooth portion is formed by molding a polyamide resin composition containing a polyamide resin as a main component. The conditions to be satisfied by the polyamide resin and the polyamide resin composition are the same as those of the gear for a steering device according to the present invention, and thus the description thereof is omitted. The central part is made of metal. However, the entire third worm wheel 113 may be formed from a polyamide resin composition.

  The third worm wheel 113 is a gear connected to the third power generation unit 110 so as to be able to transmit torque. More specifically, the third worm wheel 113 is rotated by the third power generation unit 110. The gear meshes with the worm gear 112. The third worm wheel 113 rotates integrally with the first pinion shaft 105 connected to the steering member 200 so that torque can be transmitted. The steering gear according to the present invention can also be suitably applied to such third worm wheel 113.

[Embodiment 4]
A steering apparatus 4 according to Embodiment 4 of the present invention will be described with reference to FIG. The members already described in this specification are denoted by the same reference numerals, and the description thereof is omitted below.

  As shown in FIG. 6, the steering device 4 includes a turning force generator 40 and a reaction force generator 50 instead of the second assist force generator 20 in the steering device 2.

  The turning force generator 40 includes a first power generation unit 220, a first power transmission shaft 221, a first worm gear 222, a first worm wheel 223, a second power transmission shaft 224, and a second pinion gear 225. And having a function of generating a turning force and transmitting the turning force to the rack bar 211.

  The reaction force generator 50 includes the second torque sensor 12, the second power generation unit 13, the third power transmission shaft 14, the second worm gear 15, the second worm wheel 16, and the clutch unit 17. And a function of generating a reaction force against the steering operation and transmitting the reaction force to the steering member 200.

  Further, the lower end of the second steering shaft 102 and the upper end of the third steering shaft 103 are connected via the clutch portion 17, and the lower end of the third steering shaft 103 is connected to the upper end of the intermediate shaft 104. The first universal joint 201 is connected to be interlocked with each other.

  The steering device 4 can (1) mechanically connect or disconnect the torque transmission path between the steering member 200 and the first pinion gear 210 by the clutch portion 17, and (2) the torque transmission path. This is a steer-by-wire type steering device having at least two functions of being capable of electrically controlling the turning angle of the wheel 400 in accordance with a steering operation via the steering member 200 in a state in which is interrupted. In the present embodiment, the first worm wheel 223 and the second worm wheel 16 are the steering gear according to the present invention.

  The clutch unit 17 is configured to switch between mechanical connection and disconnection of the torque transmission path between the steering member 200 and the first pinion gear 210 in accordance with the clutch control signal SL17 supplied from the control unit 300. It is. More specifically, the clutch unit 17 mechanically connects torque transmission between the lower end of the second steering shaft 102 and the upper end of the third steering shaft 103 according to the clutch control signal SL17, or Switch between blocking. Although the specific configuration of the clutch portion 17 is not limited to the present embodiment, for example, a meshing clutch having a lock mechanism using an electromagnetic solenoid, a roller clutch, or a multi-plate clutch having a plurality of clutch plates may be used. it can.

  The control unit 300 controls the torque generated by the first power generation unit 220 and the torque generated by the second power generation unit 13 in accordance with the steering operation by the driver.

  More specifically, the control unit 300 refers to the torque sensor signal SL12 supplied from the second torque sensor 12 and controls the torque generated by the second power generation unit 13. And a torque control signal SL220 for controlling the torque generated by the first power generation unit 220, and supplies the torque control signal SL220 to the second power generation unit 13 and the first power generation unit 220, respectively. The controller 300 may be configured to generate the torque control signal SL13 and the torque control signal SL220 by further referring to a signal indicating the steering angle of the steering member 200, a vehicle speed signal from a vehicle speed sensor, and the like.

  Further, the control unit 300 supplies the clutch control signal SL17 to the clutch unit 17 so as to control switching between the connected state and the disconnected state of the clutch unit 17.

  When the clutch unit 17 is in the disconnected state, the control unit 300 controls the second power generation unit 13 to generate a reaction force against the steering operation by the driver. More specifically, the control unit 300 controls the second power generation unit 13 so that a reaction torque opposite to the steering torque of the driver input via the steering member 200 is transmitted to the steering shaft. Control. As a result, the driver can obtain an operational feeling for the steering operation.

  Although the specific control method of the clutch unit 17 by the control unit 300 is not limited to the present embodiment, for example, the control unit 300 may be configured to start the clutch when an abnormality occurs in the steering device 4 or when the ignition is off. It can be set as the structure which switches the part 17 to a connection state. With such a configuration, the driver can steer the wheel 400 without going through the electrical path when an abnormality occurs or when the ignition is off.

  Further, the control unit 300 is configured so that when the clutch unit 17 is in the connected state, torque in the same direction as the driver's steering torque input via the steering member 200 is transmitted to the second steering shaft 102. It is good also as a structure which controls the 2 motive power generation parts 13. Thereby, even if the clutch part 17 is a connection state, the driver | operator can perform steering operation, without requiring big force.

  Note that only one of the first worm wheel 223 and the second worm wheel 16 may be configured as the steering gear according to the present invention.

  The physical properties of the following resins 1 to 4 were measured. Further, each resin was molded to form a tooth portion and integrated with a metal central portion to produce a worm wheel as shown in FIG. Each produced worm wheel was actually used as a worm wheel in an electric power steering apparatus as shown in FIG. 1 to evaluate its suitability.

  Polyamide 410 “EcoPaXX Q210E-H” (DSM) was used as the resin 1, and polyamide 66 “Zytel 103HSL” (DuPont) was used as the resin 2. The structural formula of polyamide 410 is shown in chemical formula 1, and the structural formula of polyamide 66 is shown in chemical formula 2, respectively.

  The results are shown in Table 1. The viscosity number was measured according to the JIS standard (JIS K6933). The tensile yield elongation was measured according to the JIS standard (JIS 7161). The water absorption is 23 ° C. 50% R.D. measured in accordance with JIS standard (JIS 7161). H. Is the equilibrium water absorption of the polyamide resin composition. The gear suitability was evaluated as ◯ when the wear and breakage of the tooth surface could be reduced, and ◎ when it was particularly reduced. The results are shown in Table 1.

  For each of the worm wheel manufactured using the resin 1 and the worm wheel manufactured using the resin 2, the torque transmitted to the worm wheel is either (A) 29.6 Nm or (B) 63.7 Nm. As follows: (1) Steering from the neutral position to (2) Steering to one limit, (3) Steering to the other steering limit, and (4) Returning to the steering neutral position The change in the backlash angle of each worm wheel was measured. The results are shown in FIG.

  As shown in FIG. 7, at any torque, when the number of cycles increases, the worm wheel (PA410) manufactured using the resin 1 is more than the worm wheel (PA66) manufactured using the resin 2. The amount of change in backlash tended to be small. That is, it was shown that the worm wheel (PA410) produced using the resin 1 has higher durability.

  In particular, when the torque is 63.7 Nm, when the number of cycles exceeds 70000, the worm wheel (PA66) manufactured using the resin 2 is more prominent than the worm wheel (PA410) manufactured using the resin 1. The backlash change amount became large. Thus, it was shown that the worm wheel produced using the resin 1 becomes more advantageous than the worm wheel produced using the resin 2 as the torque transmitted to the worm wheel increases.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

1 to 4 Steering device 10 First assist force generation device 12 Second torque sensor 13 Second power generation unit (power generation unit)
15 Second worm gear (worm gear)
16 Second worm wheel (gear for steering device, worm wheel)
DESCRIPTION OF SYMBOLS 20 2nd assist force generator 30 3rd assist force generator 40 Steering force generator 50 Reaction force generator 101 1st steering shaft 102 2nd steering shaft 103 3rd steering shaft 105 1st pinion Shaft 106 Second pinion shaft 107 First torque sensor 110 Third power generation unit (power generation unit)
112 Third worm gear (worm gear)
113 Third worm wheel (steering gear, worm wheel)
200 Steering member 210 First pinion gear 211 Rack bar (steering shaft)
211a Rack tooth 220 1st power generation part (power generation part)
222 First worm gear (worm gear)
223 First worm wheel (steering gear, worm wheel)
223a Tooth part 223b Center part 225 Second pinion gear 300 Control part 400 Wheel

Claims (9)

A gear for a steering device connected to a power generation unit provided in a steering device of a vehicle so as to be able to transmit torque,
A tooth portion formed by molding a polyamide resin composition containing a polyamide resin as a main component,
A gear for a steering device, wherein the polyamide resin has a viscosity number of 190 ml / g or more.   The steering gear according to claim 1, wherein the tensile yield elongation of the polyamide resin composition is 6% or more.   23 ° C., 50% R.D. H. The steering gear according to claim 1 or 2, wherein the polyamide resin composition has an equilibrium water absorption of 3.0% or less.   The gear for a steering apparatus according to any one of claims 1 to 3, wherein the polyamide resin is polyamide 410.   The steering gear according to any one of claims 1 to 4, wherein a content of reinforcing fibers in the polyamide resin composition is less than 5.0 mass%.   The steering gear according to any one of claims 1 to 5, which is a worm wheel that meshes with a worm gear that is rotationally driven by the power generation unit.   The steering according to claim 6, wherein the steering rotates integrally with a second pinion gear meshing with a rack tooth provided on the steered shaft at a position different from the first pinion gear connected to the steering member so as to transmit torque. Equipment gear.   The steering gear according to any one of claims 1 to 7, wherein a maximum value of torque transmitted from the power generation unit is 63.7 Nm or more. In a vehicle steering system,
A power generator,
A steering device gear connected to the power generation unit so as to transmit torque,
The steering gear is
A tooth portion formed by molding a polyamide resin composition containing a polyamide resin as a main component,
A steering apparatus, wherein the polyamide resin has a viscosity number of 190 ml / g or more.

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