JPH0427398Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a knuckle structure that connects the seat back and seat bottom of an automobile seat and adjusts the reclining of the seat back.

(Prior Art) Conventionally, as a knuckle structure for an automobile seat, the one shown in FIG. 3 is known. In FIG. 3, a bottom bracket 11 attached to the seat bottom 1 and a back bracket 21 attached to the seat back 2 are rotatably connected to each other via a main shaft 12.
This back bracket 21 has a substantially fan-shaped sector gear 3 fixed to it so as to rotate around the main shaft 12 in conjunction with the back bracket 21, and an arm-shaped lock gear 4 connected to the lock gear shaft 41 on the bottom bracket 11. Therefore, the cams 5 are each mounted by a camshaft 51 so as to be rotatable about a horizontal axis. The lock gear 4 is formed with teeth 4 that mesh with the teeth 31 formed on the periphery of the sector gear 3, and the cam 5 is arranged to press the lock gear 4 in the direction of meshing with the sector gear 3. There is.

Further, an operating lever 6 is attached to the main shaft 12 so as to be rotatable around the main shaft 12 (horizontal axis), and a pin 5 formed protruding from the cam 5 is inserted into an elongated hole 61 formed in the operating lever 6.
2 has been inserted. As a result, the operating lever 6
When the cam 5 is oscillated as shown by the solid line and the two-dot chain line in FIG. 3, the operating force is transmitted through the pin 52, causing the cam 5 to also oscillate. Due to this rocking of the cam 5, the sector gear 3 and the lock gear 4 mesh with each other, and the reclining position of the seat back 2 relative to the seat bottom 1 is locked (the state shown by the solid line in FIG. 3), or the mesh is disengaged. The lock can be released (the state shown by the two-dot chain line in the figure). Further, a tension spring 58 is attached to the operating lever 5, and the tension spring 58 biases the cam 5 to rotate in a direction that engages the sector gear 3 and the lock gear 4 with each other, whereby the seat is normally locked. I'm trying to get into the state.

When the vehicle body is rear-ended or collided with a seat to which the above-mentioned conventional Natsukuru structure is applied,
Reaction caused by a rear-end collision of the occupant or restraint of the seat belt acts on the seat, and an external force F ₀ , which is the product of the mass M of the occupant and the acceleration G, acts on the seat back 2, as shown in FIG. And this external force F ₀
is transmitted through the back bracket 21, the sector gear 3, and the lock gear 4, whereby the cam 5 has an arcuate working surface 53 of the cam 5 and a flat rear surface of the lock gear 4, as shown in FIG. 43, a force F acts perpendicularly to the rear surface 4, and a force N of the same magnitude as this force F acts on the lock gear 4 as a reaction force to the force F.

Here, the above force F is applied to the cam 5 as shown in FIG.
If the component force F ₁ is divided into a component force F 1 directed toward the rotation center b of the cam 5, and a component force F ₂ that attempts to rotate the cam 5 in the direction of unlocking (counterclockwise direction in Fig. 5), the component force F ₂ is resisted. The frictional resistance force F ₃ is the friction coefficient μ between the cam 5 and the lock gear 4 at the contact point a.
and the above reaction force N, it is expressed as F ₃ =μN (a).

By the way, if the arc constituting the action surface 53 is set so that the center of curvature c of the arc is located on the line of action of the force F, the direction of action of the component force F ₂ becomes the tangential direction of the arc. Therefore component force
F ₂ is expressed as F ₂ =F tanθ based on the angle θ between force F and component force F ₁ , and since F = N, the above component force F ₂ is F ₂ = N It is expressed by tanθ...(b).

When this component force _F2 is larger than the frictional resistance force _F3 , the cam 5 is rotated to release the lock, and as a result, the seat bag 2 falls backwards due to the external force _F0 . Therefore, in the cam 5 in the conventional knuckle structure, the arc shape of the operating surface 53 is set so that F ₂ ≦F ₃ (c) with respect to the external force F ₀ .

Specifically, the angle θ is set so as to satisfy the relationship tanθ≦μ, which is obtained by substituting the above equations (a) and (b) into equation (c). In other words, the angle when F ₂ = F ₃ , that is
The angle θ (hereinafter referred to as the friction corresponding angle) is set to be smaller than the angle θ′ (friction angle) that satisfies tanθ′=μ. By setting the friction corresponding angle θ in this way, the force F ₂ that releases the lock state is generated between the cam 5 and the lock gear 4, and the friction resistance force F ₃
The cam 5 in the conventional structure is configured so that the frictional resistance force does not become larger, that is, the above-mentioned locked state is maintained by this frictional resistance force.

However, when a dynamic load acts on the contact point a between the cam 5 and the lock gear 4 due to a rear-end collision, etc., the value of the friction coefficient μ at the contact point a decreases, and therefore the locked state cannot be maintained sufficiently. Conceivable. Therefore, it is conceivable to deal with this by adjusting the friction corresponding angle θ to be reduced in response to the decrease in the friction coefficient. However, cam 5
Since the operating surface 53 of is composed of a single circular arc, as the friction corresponding angle θ is reduced, the cam 5 will firmly bite into the lock gear 4 when a load is applied, making further operation impossible. There is a risk of it becoming.

(Purpose of the invention) This invention was made to solve such conventional problems, and the purpose of this invention is to reliably maintain a locked state in the mutual positional relationship between the seat back and the seat bottom even when dynamic loads are applied. It is possible,
Furthermore, the present invention provides a knuckle structure for an automobile seat with excellent operability.

(Structure of the invention) In this invention, a seat bottom and a seat back are rotatably connected to each other around a horizontal axis, an engaged member is fixed to one of them, and the engaged member and the other are engaged with each other. The mating engaging member is mounted so as to move in the direction of engagement with and away from the engaged member, and the cam that presses the engaging member in the direction of engaging with the engaged member swings. In the knuckle structure of the automobile seat, the cams are attached to each other and are configured to engage and release the engaged member and the engaging member by the rocking of the cams. The first arc lies on a line inclined by an angle θ ₁ from the straight line from the contact point of the cam and the engaging member to the center of rotation of the cam when a static load is applied. The second circular arc is formed so that the center of curvature is located on a line inclined by θ ₂ from the straight line from the contact point of the cam and the engaging member to the rotation center of the cam when a dynamic load is applied. The angle θ ₁ and the angle θ ₂ are the friction coefficient μ ₁ between the cam and the engagement member at the contact point when a static load is applied, and Based on the friction coefficient μ ₂ between the cam and the engaging member at the above contact point when a dynamic load is applied, it is determined to satisfy the relationship μ ₁ ≧tanθ ₁ ≧μ ₂ ≧tanθ ₂ The second circular arc is formed at one end of the working surface of the cam.

According to the above configuration, the first circular arc has a friction corresponding angle that is smaller than the friction angle corresponding to the friction coefficient when a static load is applied and larger than the friction angle corresponding to the friction coefficient when a dynamic load is applied. Therefore, when a normal static load is applied, the locked state between the cam and the mating member can be reliably maintained by the first circular arc. Furthermore, since the second circular arc is set to have a friction angle smaller than the friction angle corresponding to the friction coefficient when a dynamic load is applied, the second circular arc locks the lock when a dynamic load is applied. The condition can be maintained reliably. Moreover, since the working surface of the cam is constituted by two circular arcs, operability is not impaired.

(Embodiment) In the embodiment shown in FIGS. 1 and 2, the working surface 53 of the cam 5 in the conventional knuckle structure shown in FIG. 53b.

In FIG. 2, a first circular arc 53a is formed by a circular arc having a radius of curvature _R1 centered on a point d, and a second circular arc 53b is formed by a circular arc having a radius of curvature _R2 centered at a point e. The first circular arc 53a and the second circular arc 53b are arranged such that the second circular arc 53b is located at the tip of the cam 5 in the clockwise direction, with the point f as the intersection point. The second circular arc 53b is attached to the rear surface 43 of the lock gear (engaging member) 4 at the tip thereof.
It is formed in a range where it can at least come into contact with.

The center of curvature d of the first circular arc 53a is on the normal line of the point g on the back surface 43 of the lock gear 4 (see the dashed line in FIG. 2) in the locked state when a normal static load is applied, and It is set on a line inclined by a friction corresponding angle θ ₁ from a line segment connecting the contact point g between the cam 5 and the lock gear 4 and the rotation center b of the cam 5.
The center of curvature e of the second circular arc 53b is on the normal line of the point h on the back surface 43 of the lock gear 4 (see the two-dot chain line in FIG. 2) in the locked state when a dynamic load is applied to the cam. It is set on a line inclined by a friction corresponding angle θ ₂ from a line segment connecting the contact point h between the lock gear 4 and the rotation center b of the cam 5.

The above two friction corresponding angles θ ₁ and θ ₂ are the friction coefficient (hereinafter referred to as static friction coefficient) μ ₁ at the contact point g when a normal static load is applied, and μ 1 when a dynamic load is applied. Based on the friction coefficient (hereinafter referred to as dynamic friction coefficient) μ ₂ at the contact point h, it is determined to satisfy the relationship μ ₁ ≧tanθ ₁ ≧μ ₂ ≧tanθ ₂ (d).

When the cam 5 and the lock gear 4 are, for example, press-molded products, the static friction coefficient μ ₁ is 0.12 to 0.12.
The value is in the range of 0.2, and the dynamic friction coefficient _μ2 is in the range of 0.09 to 0.1. Therefore, in this case, the friction corresponding angle θ ₁ may be selected to have a value smaller than 6°50′ and larger than 5°40′, and the friction corresponding angle θ ₂ may be set to a value smaller than 5°10′, for example. .

The cam 5 having the above-mentioned knuckle structure is rotated clockwise by the operating lever 6, and the first circular arc 53a presses the back surface 43 of the lock gear 4 at the contact point g as shown by the dashed line in FIG. As a result, the lock gear 4 and the sector gear (engaged member) 3 are locked in a mutually meshed state.

In this state, the first arc 53a is
As shown in the equation, the friction angle θ 1 is set to be smaller than the friction angle corresponding to the static friction coefficient _{μ 1} and larger than the friction angle corresponding to the kinetic friction coefficient μ _2. Therefore, as shown in FIG. As explained in connection with the conventional knuckle structure, when a static load is applied, a frictional resistance force F ₃ equal to the component force F ₂ that attempts to release the above-mentioned locked state is generated. Therefore, this frictional resistance force F ₃
As a result, the above-mentioned rotary state is maintained reliably.

Since the first circular arc 53a is set to have a friction corresponding angle θ ₁ larger than the friction angle corresponding to the dynamic friction coefficient μ ₂ as shown in equation (d),
Even if a load is applied to the seat back 2, the cam 5 does not get caught in the lock gear 4, so the cam 5
This does not impair the operability of the operating lever 6 that rotates the .

When a dynamic load is applied to the seat back 2, the component force in the unlocking direction when a static load is applied in Fig. 5
A component force larger than F ₂ acts, and this component force becomes larger than the frictional resistance force when the static load is applied at the contact point g (see Figure 1), so the cam 5 The cam 5 rotates counterclockwise by a small angle around the rotation center b from the above-mentioned locked state shown by the solid line to the state shown by the solid line, and as a result, the cam 5 and the lock gear 4 come into contact at a point h on the second circular arc 53b. become. The cam 5 is pressed against the back surface 43 of the lock gear 4 at this contact point h, whereby the lock gear 4 and the sector gear 3 are locked in a mutually meshed state.

That is, a dynamic load acts on the seat back 12, which causes an external force Fb to act on the cam 5 as shown in FIG. 1, and this external force Fb rotates the cam 5 in the unlocking direction (counterclockwise). A component force F ₂ b is generated. This component force F ₂ b is expressed by F ₂ b = Fb tan θ ₂ = Nb tan θ ₂ based on the friction corresponding angle θ ₂ , and the frictional resistance force F ₃ b resisting this component force F ₂ b. is expressed by F ₃ b=μ ₂ Nb based on the coefficient of dynamic friction ₂ .

Here, the above [tanθ ₂ ] and [μ ₂ ] are set in the relationship of μ ₂ ≧tanθ ₂ , so the above component force F ₂ b and frictional resistance force F ₃ b are F ₃ b≧F ₂ The relationship is b. Therefore, even when a dynamic load is applied, the second circular arc 53b of the cam 5 restricts the movement of the lock gear 4 via the contact point h.
The lock gear 4 and the sector gear 3 can be reliably maintained in a mutually meshed state.

Note that when a dynamic load is applied, a minute gap is formed between the teeth 42 of the lock gear 4 and the teeth 31 of the sector gear 3, as shown in FIG.
This does not affect the position fixing function of the seat back 2 due to meshing with the sector gear 3.

(Effect of the invention) According to the knuckle structure of the automobile seat of this invention, the working surface of the cam configured to press the engaging member in the direction of engaging with the engaged member has the first circular arc and the second circular arc. The first circular arc has a friction angle smaller than the friction angle corresponding to the friction coefficient when a static load is applied and larger than the friction angle corresponding to the friction coefficient when a dynamic load is applied. Therefore, when a normal static load is applied, the first circular arc and the engaging member come into contact with each other, so that the locked state between the cam and the engaging member can be reliably maintained. .

Further, since the second circular arc is set to have a friction angle smaller than the friction angle corresponding to the friction coefficient when a dynamic load is applied, when a dynamic load is applied, the second circular arc and the engaging member The above-mentioned locked state can be reliably maintained by contacting the two.

Moreover, the second circular arc is formed at one end of the working surface of the cam, and the first circular arc that contacts the engaging member when a normal static load is applied is smaller than the friction angle corresponding to the friction coefficient under a dynamic load. Since it is set to have a large friction corresponding angle, this first circular arc will not get caught in the lock gear, and therefore operability will not be impaired.

[Brief explanation of the drawing]

Figure 1 is an enlarged front view of main parts showing an embodiment of this invention, Figure 2 is an explanatory diagram of the shape of the cam in Figure 1, and Figure 3 is an illustration of the shape of the cam in Figure 1.
The figure is a front explanatory view showing the conventional knuckle structure.
The figure is an explanatory diagram of the conventional problem, and FIG. 5 is a front explanatory diagram of a cam in the conventional knuckle structure. 1... Seat bottom, 2... Seat back, 3
... sector gear (engaged member), 4 ... lock gear (engaging member), 5 ... cam, 53 ... working surface,
53a...first circular arc, 53b...second circular arc,
b... Center of rotation of the cam, d... Center of curvature of the first arc, e... Center of curvature of the second arc, g, h...
point of contact.

Claims (1)

[Claims for Utility Model Registration] A seat bottom and a seat back are connected to each other so as to be rotatable around a horizontal axis, and an engaged member is fixed to one of them, and the engaged member and the other are mutually engaged with each other. The engaging member is mounted so as to move in a direction in which it engages with the engaged member and in a direction in which it separates from the engaged member, and a cam that presses the engaging member in a direction that engages with the engaged member is swingable. In the knuckle structure of the automobile seat, the cams are attached to the cams, and the cams have two working surfaces. The first arc lies on a line inclined by an angle θ ₁ from the straight line from the contact point of the cam and the engaging member to the center of rotation of the cam when a static load is applied. The second circular arc is formed so that the center of curvature is located on a line inclined by an angle θ ₂ from the straight line from the contact point of the cam and the engaging member to the rotation center of the cam when a dynamic load is applied. The angle θ ₁ and the angle θ ₂ are the friction coefficient μ ₁ between the cam and the engagement member at the contact point when a static load is applied. , based on the friction coefficient μ ₂ between the cam and the engaging member at the above contact point when a dynamic load is applied, so as to satisfy the relationship μ ₁ ≧tanθ ₁ ≧μ ₂ ≧tanθ ₂ A knuckle structure for an automobile seat, wherein the second circular arc is formed at one end of an operating surface of a cam.