JPH1120517A - Lock tooth part of seat reclining device for automobile and hardening method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lock tooth part of a seat reclining device for an automobile which satisfies the requirements for abrasion resistance and impact resistance and is also excellent in workability while realizing high hardness. SOLUTION: In a seat reclining device where an arm 5 fixed to a side part of a seat back is rotatably pivoted on a baseplate 1 mounted on a car body, and an inclination of the seat back can be adjusted by arranging and releasing a tooth part 7 or a tooth prate 3 arranged on the arm 5 side and a tooth part 10 of a tooth member 11 arranged on the baseplate 1 side, the tooth plate 3 and the tooth member 11 are formed of a medium carbon material, and high frequency quenching is performed on a surface layer part of its tooth parts 7 and 10, and a quenching layer is arranged, and shot peening is performed on surfaces of these tooth parts 7 and 10, and a hardening layer is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a locking tooth portion of an automobile seat reclining device and a method of hardening the locking tooth portion, and has improved strength and durability of a tooth portion of a tooth plate and a tooth member.

[0002]

2. Description of the Related Art A seat reclining device is often used as a seat device of an automobile, and a locking mechanism by meshing teeth is used as a mechanism for adjusting an inclination angle of a seat back of the seat reclining device. In a conventionally known external tooth type seat reclining device, a tooth plate integrated with an arm is rotatably supported by a center shaft on a base plate fixed to a seat cushion, and a seat back is fixed to the arm. A tooth plate having teeth formed on a circumference of a predetermined radius centered on a center shaft, and a tooth member rotatably supported by a base plate having teeth engaging with the teeth. The tooth member is engaged and disengaged by interlocking the tooth member with a cam member that rotates integrally with the operation lever.

[0003] Recently, there has been provided an internal toothed seat reclining device, in which a concave portion is formed by embossing a tooth plate connected to an arm fixed to a seat back, and a locking mechanism is provided for the concave portion. A tooth portion is formed on the inner peripheral surface, and a tooth member having a tooth portion engaged with the tooth portion is arranged so as to be able to advance and retreat toward the tooth portion by engaging with a guide portion formed on a base plate, The tooth member is moved forward and backward by an operation lever to engage and disengage both teeth.

[0004]

However, the seat reclining device forms a center of rotation for supporting the load of the occupant applied to the seat back at the set desired inclination angle.
Particularly, in order to protect the occupant in the event of a vehicle collision, it is necessary to use a high-strength member, and in view of recent traffic conditions, there is an increasing demand for improved safety.

[0005] The locking teeth of the seat reclining device have not only high strength but also abrasion resistance for reducing abrasion due to sliding between the teeth and resistance for preventing chipping when teeth collide. Impact properties and the like are required, and it is desired to improve strength while satisfying these requirements.

[0006] As a conventional method of hardening a lock tooth portion, a carburizing quenching method and an induction hardening method are known.

In this carburizing and quenching method, a low carbon material (S20C or less) is used, and the surface layer is hardened by carburizing and quenching. This carburizing and quenching method has the advantages of using a relatively soft, low-carbon material, so that it has good workability and good mold holding during press molding.On the other hand, it relies on the hardened surface layer for the strength of the teeth. Therefore, there is a disadvantage that the strength of the teeth cannot be increased so much. Therefore, in order to improve the strength, it is conceivable to use a material that is higher than the medium carbon material, but the carbon content of the surface layer after carburizing and quenching becomes too high, and the hardness becomes high but becomes brittle.
Poor impact resistance causes inconvenience such as chipping.

In the induction hardening method, a high carbon material (S45C or more) is used, and the surface layer is hardened by induction hardening. In this induction hardening method, only the necessary parts can be heated and quenched with high frequency, so quenching is easy and productivity is high.On the other hand, in order to obtain the surface hardness required for abrasion resistance, a hard high carbon material is used. Since it must be used, there is a drawback that the workability is poor and the mold holding at the time of press molding is poor, and also that the hardness of the entire tooth portion is high, so that chipping easily occurs. Therefore, in order to prevent tooth chipping and improve workability, it is conceivable to use a material of medium carbon or less, but the hardness obtained by induction hardening decreases and the hardness required for wear resistance cannot be obtained. Inconvenience occurs.

In the present invention, a material having S20C or less is referred to as a low carbon material, a material having S45C or more is referred to as a high carbon material, and a material therebetween is referred to as a medium carbon material.

Accordingly, the present invention provides a lock tooth portion of a seat reclining device for an automobile which satisfies the requirements of wear resistance and impact resistance while improving strength, and provides a method of hardening the lock tooth portion. Things.

[0011]

A locking tooth portion of a vehicle seat reclining device according to the present invention pivotally supports an arm fixed to a side portion of a seat back on a base plate mounted on a vehicle body. A seat reclining device in which an inclination angle of a seat back can be adjusted by engaging and disengaging a tooth portion of a tooth plate provided on an arm side and a tooth portion of a tooth member provided on a base plate side; The plate or tooth member is formed of a medium carbon material, and the surface layer of the tooth portion is subjected to induction hardening to provide a quenched layer, and the surface of the tooth portion is subjected to shot peening to provide a hardened layer. It is characterized by.

Further, according to the present invention, there is provided a method of hardening a lock tooth portion of an automobile seat reclining device, wherein an arm fixed to a side portion of a seat back is rotatably supported on a base plate mounted on a vehicle body. A method of hardening a lock tooth portion in a seat reclining device in which a tilt angle of a seat back can be adjusted by disengaging a tooth portion of a tooth plate provided on an arm side and a tooth portion of a tooth member provided on a base plate side. A tooth portion is formed on a tooth plate or a tooth member made of a medium carbon material, and induction hardening is performed on the tooth portion and its peripheral portion to provide a quenched layer on a surface layer portion. It is characterized by providing a hardened layer by shot peening.

[0013] Therefore, by using a medium carbon material for the tooth plate and the tooth member and performing induction hardening on the surface layer portion of the tooth portion to provide a quenched layer, it is possible to increase the strength and at the time of collision between the teeth. An automobile that can secure the impact resistance to prevent chipping of the teeth and improve the wear resistance by reducing the abrasion due to the sliding between the teeth by applying shot peening to the surface of the teeth and providing a hardened layer Locking tooth portion of the seat reclining device can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an internal-tooth-type seat reclining device for an automobile, and as shown in the drawing, a base plate 1 fixed to a vehicle body via a not-shown seat slide device or the like.
A tooth plate 3 is rotatably mounted on a shaft via a center shaft 2. An arm 5 is connected to the tooth plate 3 via a connection hole 4, and the arm 5 is fixed to a side surface of a seat back (not shown). Note that the tooth plate 3 may be directly fixed to the side surface of the seat back without using the arm 5. An arc portion 1a having a predetermined radius centering on the center shaft 2 is formed on an upper side of a base plate 1 fixed to a seat cushion (not shown).

On the side of the tooth plate 3 facing the base plate 1, a sector-shaped concave portion 6 having a predetermined radius around the center shaft 2 is formed by embossing or the like.
The teeth 7 are formed on the arc-shaped inner peripheral wall of the recess 6 by press molding. At the upper end of the tooth plate 3, a plate-like body 9 connected by pins 8 inserted into the connection holes 4 is fixed to the tooth plate 3, and the plate-like body 9 slides on the arc portion 1a of the base plate 1 as a pressing member. It is pressed so as not to come off and come off to the tooth plate 3 side.

That is, the plate-like body 9 is formed with an arc-shaped stepped portion 9a which is in sliding contact with the arced portion 1a within a predetermined range. The plate-like body 9 is fixed to the tooth plate 3 by a pin 80 penetrating through the connection hole 9c and the connection 4a of the tooth plate 3,
The pin 8 penetrates the connection hole 4, the connection hole 5 a of the arm 5, and the connection hole 9 b of the plate 9 and fastens them together. Instead of the plate-like body 9, the head of the pin 8 is expanded to form a flange portion, and the pin 8 is inserted into the connection hole 4 so that the flange portion separates the arc portion 1 a of the base plate 1. The sliding contact may be made between the two points.

A tooth member 11 having an upper edge formed with a tooth portion 10 meshing with the tooth portion 7 is slidably housed in a concave portion 1b formed in the base plate 1, and is sandwiched between the base plate 1 and the tooth plate 3. The base plate 1 is provided with guide portions 12 and 13 formed of convex portions or concave portions having guide surfaces for slidingly guiding the tooth member 11 in the radial direction. The tooth member 11 has side portions 14, 14 parallel to the guide portions 12, 13 and arm portions 15 projecting obliquely in a direction crossing the side portions 14, 14. The tooth member 11 is disposed within a triangular range formed by the plate-shaped body 9 and the center shaft 2, and the teeth 7, 10 are disengaged within the triangular range.

Cam member 19 for sliding tooth member 11
Are housed in the recess 6 and the recess 1b of the base plate 1 so as to be rotatable about the center shaft 2 while being sandwiched between the base plate 1 and the tooth plate 3. The cam member 19 has a head portion 20 abutting on the side of the tooth member 11 opposing the tooth portion 10,
And an arm 21 for sliding the tooth member 11 to release the meshing of the teeth 7 and 10 by contacting the teeth.

The center shaft 2 has a flange 22 and is inserted through the tooth plate 3, penetrates through the cam member 19, the operating lever 23 and the base plate 1, and engages with the base plate 1 at the irregularly shaped cross section 24 so that it cannot rotate. And fixed to the base plate 1 by caulking the outside. A spiral spring 27 is provided at the other end of the center shaft 2.
The outer end of the spiral spring 27 is engaged with a pin 28 projecting from the tooth plate 3 and projecting outward. Therefore, the tooth plate 3 is always urged to rotate forward.

The operating lever 23 forms an embossed portion 33 near the center shaft 2, and a hole 34 for fitting the embossed portion 33 is formed in the cam member 19 and fitted. The member 19 is integrally rotatable. A knob 35 is mounted on a free end of the operation lever 23. One end of a return spring 36 is locked to the operation lever 23, and the other end of the return spring 36 is locked to a pin 37 protruding from the base plate 1.

Here, as shown in FIG. 2, the tooth plate 3 is formed by press-molding a plate-like material made of a medium carbon material, and has an arc-shaped inner peripheral wall 6a having a predetermined radius.
Is formed in an embossed shape, and a tooth portion 7 as a lock tooth portion is press-formed on the arc-shaped inner peripheral wall 6a.

The teeth portion 7 of the tooth plate 3 and the peripheral portion B thereof are subjected to induction hardening to form a quenched layer 3, and the quenched layer 3a is 0.5 mm from the surface.
It is formed with a depth of about 1.0 mm.

Thereafter, the tooth portion 7 of the tooth plate 3 and the peripheral portion B thereof are subjected to a surface treatment by a shot peening method. In this shot peening method, a small steel grain shot is beaten to the metal surface with compressed air or centrifugal force to uniformize the surface stress.
mm, HRC hardness of 53 steel grains at 55-65 m / sec.
Irradiate for ~ 5 minutes. As a result, the surfaces of the tooth portions 7 of the tooth plate 3 and the peripheral portion B thereof are beaten by the steel grains, so that the residual stress during quenching can be made uniform and the surface is hardened to form a hardened layer 3b. This cured layer 3
b is formed at a depth of 5 to 20 μm from the surface.

The surface treatment by the shot peening method may be applied to the entire surface of the tooth plate 3. In this case, since the surface roughness of the tooth plate 3 is improved, the surface is slid on the contact surface with the base plate 1. It is possible to prevent the generation of contact sounds. Further, since the tooth member 11 is formed in the same manner as the tooth plate 3, the description thereof is omitted.

Next, the operation of the above-mentioned internal toothed seat reclining device will be described.
6 rotates clockwise around the center shaft 2 against the force of the center shaft 2, the cam member 19 also rotates clockwise, the head 20 comes off the lower surface of the tooth member 11, and the arm portion 21 The tooth member 11 is slid in the direction of the center shaft 2 in contact with the portion 15 to release the meshing of the teeth.

Therefore, the tooth plate 3 rotates in the forward falling direction by the force of the spiral spring 27. Then, when the seat back is pushed rearward to determine its inclination angle and the operation lever 23 is released, the operation lever 23 is actuated by the force of the return spring 36.
Is returned to the original position, the cam member 19 rotates counterclockwise, the arm portion 21 is separated from the arm portion 15 of the tooth member 11, and the head 20 of the cam member 19 is The lower portion is slid in contact with the lower side, whereby the teeth portions 10 and 7 are engaged with each other to be in a locked state.

In this locked state, in the event of a vehicle collision, the occupant is pressed against the seat back, and a high load acts on the meshing surfaces of the teeth 7, 10, but a medium carbon material is used for the tooth plate 3 and the tooth member 11. In addition, a hardened layer 3a formed by induction hardening is provided on the surface portions of the tooth portions 7, 10.
Is formed, sufficient strength to withstand a high load can be secured.

When the seat back is raised from the forward tilted position, the tooth plate 3 is rotated by the rotation of the seat back, and the teeth 7 and 10 are engaged at the reclining position. At this time, when the seat back moves fast, the top portions may collide with each other without engaging the tooth portions 7 and 10, but a quenched layer is formed on the surface layer by induction hardening using a medium carbon material and hardened. Since the layer is formed very thin, the tooth portions 7, 10 are tough, prevent chipping, and have excellent impact resistance.

Further, when the tooth portion 7 of the tooth plate 3 and the tooth portion 10 of the tooth member 11 are disengaged from each other, they come into sliding contact with each other under a load, but the surface of the tooth portions 7, 10 is shot peened. Since the thin hardened layer 3b is formed by applying the method, wear can be reduced and wear resistance can be improved.

As described above, according to the embodiment of the present invention, the tooth plate 3 and the tooth member 11 are
A surface layer of the teeth 7, 10 is formed by induction hardening to provide a quenched layer 3a, and a surface of the teeth 7, 10 is shot-peened to provide a hardened layer 3b. In addition, it is possible to secure the impact resistance to prevent the chipping when the teeth collide with each other, and to reduce the wear caused by the sliding of the teeth. As a result, it is possible to obtain a lock tooth portion which satisfies all requirements for high strength, impact resistance, wear resistance, and the like required for an automobile seat reclining device.

In the embodiment of the present invention, a medium carbon material is used for the tooth plate 3 and the tooth member 11, and among the materials S30C to S40C, the strength and toughness of the quenched layer after induction hardening are both high. Since the hardness is high and the hardness of the hardened layer obtained by the shot peening method can be increased, it is particularly suitable as a material for a lock tooth portion of an automobile seat reclining device.

FIG. 5 shows an example in which the present invention is applied to a well-known external-tooth type seat reclining device. The tooth portions 5 formed on the arm 5a and the tooth member 11a respectively are shown.
Materials and processes similar to those described above are adopted for a and 11a. That is, the arm 5 and the tooth member 11 are S30C to S40.
C is formed of a medium carbon material, and after the teeth portions 5b and 11a are induction hardened, the surfaces are treated by a shot peening method. In FIG. 2, the same reference numerals are used for the same components as those of the internal toothed seat reclining device.
Reference numeral 34 denotes a holder plate fixed to the base plate 1, 35 denotes a retaining washer for the center shaft 2, 37 denotes a pressure contact plate that slides on the arm 5, and 37 and 38 denote wave washers. The tooth member 11 is forcibly rotated upward by a pin 39 projecting from the operation lever.

Further, the present invention may be applied to a lock tooth portion of a well-known planetary gear type or taumel type steplessly adjustable seat reclining device.

FIG. 6 is a graph showing the relationship between the materials described in this specification and the hardness obtained by each curing method. The hardness obtained varies depending on the variation of the material, the conditions of the curing method, and the like. Therefore, each line of the graph is merely an example, and the actual hardness has a width above and below each line of the graph.

[0035]

According to the present invention described above, a high strength is achieved by using a medium carbon material for the tooth plate and the tooth member and performing induction hardening on the surface layer of the tooth portion to provide a quenched layer. At the same time, it is possible to secure impact resistance to prevent chipping when teeth collide with each other, and to provide wear hardening by applying shot peening to the surface of these teeth to reduce wear caused by sliding between teeth. Since the wear resistance can be improved with a small amount, a lock tooth portion particularly suitable as a seat reclining device for an automobile can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an internal toothed seat reclining device showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a lock tooth portion of a tooth plate.

FIG. 3 is a sectional view of a lock tooth portion.

FIG. 4 is an enlarged sectional view showing a surface portion of a lock tooth portion.

FIG. 5 is an exploded perspective view of a conventional seat reclining device to which the present invention can be applied.

FIG. 6 is a graph showing the relationship between the material used in the present invention and the hardness obtained by each curing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base plate 2 ... Center shaft 3 ... Tooth plate 5 ... Arm 6 ... Concave part 7, 10, 5b, 11a ... Tooth part 11 ... Base plate 12, 13 ... Guide part 51 ... Internal tooth 56 ... External tooth

Claims (2)

[Claims] An arm fixed to a side portion of a seat back is rotatably supported on a base plate mounted on a vehicle body, and a tooth portion of a tooth plate provided on the arm side and a tooth provided on the base plate side. A seat reclining device in which the inclination angle of a seat back is adjustable by engaging and disengaging a tooth portion of a member, wherein the tooth plate or the tooth member is formed of a medium carbon material, and A lock tooth portion of an automobile seat reclining device, wherein a surface layer portion is subjected to induction hardening to provide a hardened layer, and a surface of the tooth portion is subjected to shot peening to provide a hardened layer. 2. An arm fixed to a side portion of a seat back is rotatably supported on a base plate mounted on a vehicle body, and a tooth portion of a tooth plate provided on the arm side and a tooth provided on the base plate side. A method of hardening a lock tooth portion in a seat reclining device in which a tilt angle of a seat back is adjustable by disengaging a tooth portion of a member, wherein the tooth portion is formed on a tooth plate or a tooth member made of a medium carbon material. After forming a hardened layer on the surface by applying induction hardening to the teeth and the periphery thereof, and applying a shot peening to the surface of the teeth, a hardened layer is provided. Hardening method for lock teeth of seat reclining equipment.