JP2002115733A - Drum brake with shoe gap-automatic adjustment mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake with shoe gap-automatic adjustment mechanism in which assembly of a temperature sensitive deformation member for preventing an over-adjustment is easy. SOLUTION: A temperature sensitive deformation member 60 having a cylindrical shape with a bottom constituted by a bimetal is adopted and is rotatably arranged between a second strut member 42 and an adjuster wheel 44 in the state that an engagement shaft 50 is inserted into a through hole 64 provided on the bottom part of the cylindrical shape with a bottom. A plurality of slits are provided on a cylindrical part positioned at an outer periphery side of the second strut member 42. The temperature sensitive member 60 becomes a larger diameter than that of the adjuster wheel 44 by enlarging a diameter of a tip end at an opening side accompanying with a raising of temperature to engage with an adjust lever 52. The adjust lever 52 is engaged with the adjuster wheel 44 and it is forbidden that an automatic adjustment of the shoe gap is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake having an automatic shoe gap adjusting mechanism, and more particularly to a technique for preventing an over-adjustment in which a shoe gap becomes too small.

[0002]

2. Description of the Related Art (a) A pair of first strut members and a second strut member respectively non-rotatably engaged with one and the other of a pair of expandable brake shoes,
An adjuster wheel disposed between the strut members, screwed to the first strut member, and relatively rotatably fitted to the second strut member via a fitting shaft; A strut for defining the approach position of the pair of brake shoes during non-braking, and (b) a pair of brake shoes that are rotatably disposed on one of the shoe webs of the pair of brake shoes and that are used for braking. An adjusting lever that is rotated in accordance with the amount of expansion of the adjuster wheel, and is engaged with the adjuster wheel when the amount of expansion exceeds a certain amount to rotate the adjuster wheel. With the rotation of the adjuster wheel, the first strut member is separated from the adjuster wheel by the action of a screw, so that the entire length of the strut is extended. Drum brakes provided with an automatic shoe gap adjusting mechanism for automatically adjusting the shoe gap between the pair of brake shoes and the rotating drum by separating the approaching positions of the pair of brake shoes in general are widely used as service brakes and parking brakes for vehicles. Used. According to such a shoe gap automatic adjusting mechanism-equipped drum brake, for example, the shoe gap between the rotating drum and the brake shoe becomes large due to wear of the brake shoe, and the amount of expansion of the brake shoe during braking is previously determined. When the predetermined amount is exceeded, the adjuster wheel is rotated by the adjust lever to extend the strut, and the shoe gap is automatically adjusted so as to have a substantially constant value set in advance. , And the operation amount of the parking brake operation lever is maintained substantially constant.

When the rotating drum is elastically deformed by the pressing force and the inner diameter is enlarged, for example, during rapid braking in which the brake shoe is pressed against the rotating drum by a large pressing force by an actuator such as a wheel cylinder, the braking force is increased. Even when the wear of the shoe has not progressed, the automatic adjustment of the shoe gap may be performed when the expansion amount exceeds the above-described predetermined amount. In such a case, the automatic adjustment of the shoe gap is performed. Then, when the brake is released thereafter, the shoe gap becomes too small, resulting in over-adjustment, which may cause friction of the brake.

On the other hand, at the time of sudden braking as described above, frictional heat is generated by sliding between the rotating drum and the lining of the brake shoe, and the temperature of the drum brake rises. It has been proposed to prevent the above-mentioned unnecessary automatic adjustment of the shoe gap by utilizing the shape change accompanying the temperature rise of the bimetal. JP-A-8-
The device described in Japanese Patent No. 105472 is an example of such a device, in which a temperature-sensitive deformable member that is deformed as the temperature of a bimetal or the like is deformed is attached to the second strut member, and the second strut member is engaged with an adjust lever by the deformation, thereby making the adjustment. The lever is separated from the adjuster wheel to prevent engagement with the adjuster wheel.

[0005]

However, such a conventional temperature-sensitive deformable member is elastically attached to the second strut member by a holding portion for gripping the second strut member, or is fixed to the second strut member by a fixing means such as a pin. Therefore, the assembling of the temperature-sensitive deformable member is troublesome and not always satisfactory. If the holding force of the holding portion is weakened, the assembling becomes easy, but it is not appropriate because the posture of the temperature-sensitive deformable member is likely to change or detach due to vibration or the like.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a drum brake with an automatic shoe clearance adjusting mechanism in which a temperature-sensitive deformable member for preventing overadjustment can be easily assembled. Is to do.

[0007]

In order to achieve the above object, a first aspect of the present invention is to provide (a) a pair of first struts which are respectively non-rotatably engaged with one and the other of a pair of expandable brake shoes. A first and a second strut member and the first strut member disposed between the first and second strut members;
An adjuster wheel screwed to the strut member and relatively rotatably fitted to the second strut member via a fitting shaft, and defines an approach position of the pair of brake shoes during non-braking. With struts,
(b) The brake shoe is rotatably arranged on one of the shoe webs of the pair of brake shoes, and is turned in accordance with the expansion amount of the pair of brake shoes during braking, and the expansion amount is An adjust lever that is engaged with the adjuster wheel to rotate the adjuster wheel when the amount exceeds a certain amount, and (c) the first strut member is moved by the action of a screw with the rotation of the adjuster wheel. An automatic shoe gap adjusting mechanism for automatically adjusting the shoe gap between the pair of brake shoes and the rotating drum by separating the approach position of the pair of brake shoes during non-braking by separating the strut from the adjuster wheel to extend the entire length of the strut. (D) a through-hole through which the fitting shaft can be inserted is fitted to the fitting shaft, and the second strut member While being held between the adjuster wheel and being deformed as the temperature rises, it is engaged with the adjust lever to prevent rotation of the adjuster wheel by the adjust lever. A heat deformation member is provided.

According to a second aspect of the present invention, there is provided a drum brake with an automatic shoe gap adjusting mechanism according to the first aspect of the present invention, wherein (a) the temperature-sensitive deformable member has a bottomed cylindrical shape, and (b) the bottomed cylindrical shape. The bottom portion is provided with the through hole and is rotatably disposed between the second strut member and the adjuster wheel. (C) The cylindrical portion located on the outer peripheral side of the second strut member has a shaft. A large number of slits are provided in the direction, and the leading end on the opening side is increased in diameter to the outer peripheral side as the temperature rises, so that the diameter becomes larger than the adjuster wheel, and the adjust lever engages with the adjuster wheel. It is characterized in that it is designed to prevent such a situation.

A third aspect of the present invention is the drum brake with an automatic shoe gap adjusting mechanism according to the first aspect of the present invention, wherein the temperature-sensitive deformable member is (a) provided with the through hole and fitted to the fitting shaft; (B) a flat fitting plate portion sandwiched and held between the two strut members and the adjuster wheel;
An engagement portion that is provided to extend from a part of the outer peripheral edge of the engagement plate portion and is engaged with the adjust lever by being deformed with a rise in temperature; and (c) an axis of the engagement shaft. And a positioning portion for positioning the engagement portion so that the engagement portion can be engaged with the adjustment lever around the center.

According to a fourth aspect of the present invention, in the drum brake with an automatic shoe gap adjusting mechanism according to the first aspect, the temperature-sensitive deformable member is (a) provided with the through hole and fitted to the fitting shaft; (B) a flat fitting plate portion sandwiched and held between the two strut members and the adjuster wheel;
It extends substantially parallel to the axial direction of the second strut member from the outer peripheral edge of the fitting plate portion, and is bent outward by approximately 180 ° so as to form a substantially U-shape. An engaging portion engaged with the adjust lever by being deformed so that the opening side is expanded is integrally provided.

[0011]

According to the first aspect of the present invention, in the drum brake with the automatic shoe gap adjusting mechanism, the second strut member is inserted through the through hole of the thermosensitive deformation member through the through hole of the thermosensitive deformation member. Since the assembly of the temperature-sensitive deformable member can be performed at the same time simply by fitting the adjuster wheel and the adjuster wheel, it is easy to assemble the temperature-sensitive deformable member,
Since the fitting shaft is inserted through the through hole, there is no danger that the temperature-sensitive deformable member will fall off due to vibration of the wheels or the like.

In the second invention, the bottomed cylindrical temperature-sensitive deformable member is used, and is rotatably disposed between the second strut member and the adjuster wheel. And the assembling work is further facilitated, and a temperature-sensitive deformable member can be attached to the conventional strut without any change to prevent over-adjustment.

According to a third aspect of the present invention, there is provided a temperature-sensitive deformable member, wherein an engaging portion is provided on a part of an outer peripheral edge of a fitting plate portion held between the second strut member and the adjuster wheel, and the engaging portion is provided with an adjusting member. Since the positioning portion is positioned by the positioning portion so as to be engaged with the lever, the material cost is reduced and the weight is reduced as compared with the bottomed cylindrical temperature-sensitive deformable member of the second invention.

In the temperature-sensitive deformable member according to a fourth aspect of the present invention, a substantially U-shaped engaging portion is provided on an outer peripheral edge of a fitting plate portion held between the second strut member and the adjuster wheel, and the temperature increases. The U-shaped opening side is deformed so as to expand so that it can be engaged with the adjustment lever. Since the change is large and the displacement required to prevent the automatic adjustment of the shoe gap by the adjustment lever can be secured, it can be arranged in a small space.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fitting shaft is provided on one of a second strut member and an adjuster wheel,
It is fitted into a fitting hole provided on the other side. The first strut member and the adjuster wheel are each provided with a screw shaft having a male screw on one of them, and screwed into a screw hole provided on the other. At least one of the fitting shaft and the screw shaft is desirably provided on the adjuster wheel,
Both axes can also be provided on the adjuster wheel.

The adjusting lever is preferably disposed on the brake shoe on the second strut member side where the positional relationship with the adjuster wheel does not change during non-braking, but may be disposed on the opposite brake shoe. is there. When the adjust lever is provided on the brake shoe on the second strut member side, for example, the adjust lever is provided rotatably around a mounting axis perpendicular to the shoe web of the brake shoe and provided between the brake shoe and the brake shoe. Is biased in one rotation direction by a given spring (such as a tension coil spring or a torsion coil spring), and is always engaged with the second strut member, and the second strut member is biased toward the first strut member. When the pair of brake shoes are expanded during braking, the struts are moved to follow the brake shoes on the opposite side with the expansion, and are rotated around the mounting shaft with the movement. It is configured to be. A spring is provided between the second strut member and the brake shoe on the opposite side so that the second strut member moves following the brake shoe on the opposite side during braking, and the adjust lever is moved to the second strut member. By mechanically engaging the second strut member, the second strut member can be rotated around the mounting axis as the second strut member moves.

The pair of brake shoes are expanded by an actuator such as a hydraulic wheel cylinder or an electric motor at the time of braking, and at the time of non-braking.
Although it is configured to be brought close to and brought into contact with a strut by a return spring (a tension coil spring or the like) arranged over a pair of brake shoes, the actuator can be expanded and approached by the actuator. For example, various modes are possible.

In a mode in which the rotation of the adjuster wheel by the adjust lever is prevented by engaging the temperature-sensitive deformable member with the adjust lever, for example, the adjust lever is separated from the adjuster wheel to prevent engagement with the adjuster wheel. However, the rotation of the adjustment lever itself may be prevented.

As the temperature-sensitive deformable member, a bimetal that deforms due to a difference in the coefficient of thermal expansion between two or more kinds of plate materials is preferably used, but other materials such as a shape memory alloy can also be used.

The positioning portion of the temperature-sensitive deformable member according to the third invention is
A protrusion engaged with a notch groove provided on an outer peripheral portion of the second strut member, a flat portion provided on the second strut member, or a shoe web of a brake shoe engaged with the second strut member Various modes are possible, such as a U-shaped portion, a notch groove, etc., which are non-rotatably engaged with, for example. This positioning portion may be provided so as to extend from the outer peripheral edge of the fitting plate portion separately from the engaging portion, but may be provided on the engaging portion.

The temperature-sensitive deformable member of the fourth invention may have a large number of U-shaped engaging portions provided with a predetermined gap (slit) all around the fitting plate portion as in the second invention, A single engaging portion may be provided on a part of the outer peripheral edge of the fitting plate portion, and a positioning portion for positioning at a predetermined assembly position where the adjusting plate can be engaged with the adjusting lever may be provided. Third invention, fourth
In general, the outer peripheral shape of the fitting plate portion of the invention is circular.
There is no particular limitation, for example, it may be a square such as a square or a hexagon.

The present invention is preferably applied to a leading / trailing type drum brake, but can also be applied to other drum brakes having an automatic shoe clearance adjusting mechanism for automatically adjusting a shoe clearance by a strut having an adjuster wheel. . Further, since the present invention is a technology based on heat generation due to friction, the present invention is suitably applied to an automatic shoe gap adjusting mechanism for automatically adjusting a shoe gap during braking by a service brake.

Also, the automatic adjustment of the shoe gap by the adjusting lever can be performed by rotating the adjuster wheel with the adjusting lever when the pair of brake shoes is expanded, but also when the pair of brake shoes are approached with the release of braking. The adjuster wheel may be rotated by a lever. The adjuster wheel is provided with, for example, a saw tooth on an outer peripheral portion, and is configured to be rotated only in one direction in which the strut is extended.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing a leading / trailing type drum brake 8 to which the present invention is applied.
(a) is a front view, (b) is an enlarged cross-sectional view taken along the line BB in (a), and a backing plate 10 fixed to a vehicle body-side member that rotatably supports wheels has an arc shape. A pair of brake shoes 12 and 14 formed by the shoe hold-down devices 16 and 18 are provided so as to be expandable with each other.
The brake shoes 12 and 14 are attached to the backing plate 10.
And a shoe rim 2 fixed to the outer peripheral edge of the shoe web 20 located substantially parallel to the plate surface of the shoe web 20.
2 and a lining 24 fixed to the outer peripheral surface of the shoe rim 22. In this embodiment, the rotation direction of the wheels, that is, the rotating drum 27 during forward running of the vehicle is clockwise in FIG. 1A, the right brake shoe 14 is a leading shoe, and the left brake shoe 12 is a trailing shoe. Shoe.

One end (upper end) of the pair of brake shoes 12 and 14 is engaged with both ends of a wheel cylinder 26 fixed to the backing plate 10, respectively, so as to brake the service brake, that is, a brake operating member. When the brake pedal is depressed, the wheel cylinder 26 is expanded in a direction in which the brake pedal is separated from each other, and is pressed by a rotating drum 27 that rotates together with the wheels to generate a braking force. At a position near the wheel cylinder 26 and on the inner peripheral side of the backing plate 10, a return spring (a tension coil spring in the embodiment) 28 is stretched over the brake shoes 12, 14.
The struts 3 are urged in a direction approaching each other and are inserted through the inside of the return spring 28.
0, and a pair of brake shoes 1 approached according to the urging force of the return spring 28 during non-braking.
The approach positions of 2, 14 are defined. The other ends (lower ends) of the brake shoes 12 and 14 are
The anchors 32 abut on the backing plate 10 respectively.

On the surface of the shoe web 20 of the brake shoe 12 on the backing plate 10 side, the axis of a mounting shaft 36 substantially perpendicular to the shoe web 20 at a position where the parking lever 34 is located on the wheel cylinder 26 side. While being attached rotatably around,
The strut 30 is disposed to straddle the parking lever 34 and the other brake shoe 14.
Accordingly, when the parking brake operation lever provided in the driver's seat is operated and the parking lever 34 is rotated counterclockwise through the mounting cable 36 via the brake cable 38, the brake shoe 14
Is moved to the right and is pressed by the rotating drum 27 to generate a braking force, and the brake shoe 12 is moved to the left along with the mounting shaft 36 by a reaction, and is pressed by the rotating drum 27 to generate a braking force. I do. The parking lever 34 is held at a fixed standby position where the engagement projection 34a abuts on the shoe rim 22 of the brake shoe 12 by the action of the return spring 28 when the parking brake is not operated, and the brake shoe 12 is
The approach position is defined by struts 30 via 4.

The strut 30 includes a parking lever 34
The first strut member 40 is non-rotatably engaged with the one brake shoe 12 around the axis via the first strut member 12 and is non-rotatably engaged with the shoe web 20 of the other brake shoe 14 via the axis. Second strut member 42
And an adjuster wheel 44 rotatably disposed about the axis between the strut members 40 and 42. The disc-shaped adjuster wheel 44 includes:
A screw shaft 48 provided with a male screw and a cylindrical fitting shaft 50 are integrally provided on a center line so as to protrude in opposite directions, and the screw shaft 48 is provided in a screw hole provided in the first strut member 40. On the other hand, the fitting shaft 50 is fitted in a fitting hole provided in the second strut member 42 so as to be relatively rotatable.

The adjuster wheel 44 constitutes an automatic shoe gap adjusting mechanism 54 together with an adjust lever 52 disposed on the brake shoe 14, and when the adjuster wheel 44 is rotated in one direction by the adjust lever 52, The first strut member 40 is separated from the adjuster wheel 44 by the action of the screw, the overall length of the strut 30 is extended, and the approach position of the pair of brake shoes 12, 14 during non-braking is separated, whereby the lining 24 Regardless of the wear, the shoe gap between the brake shoes 12, 14 and the rotating drum 27 (the sum of both) is maintained substantially constant.

The adjustment lever 52 is disposed so as to be rotatable around the axis of a mounting shaft 56 perpendicular to the shoe web 20 of the brake shoe 14 and provided between the brake shoe 14 and the adjustment lever 52. The tension coil spring 58 urges the mounting shaft 56 counterclockwise, so that the engaging portion 52 a is always engaged with the second strut member 42, and the second strut member 42 is attached to the first strut member 40. I'm going. Thus, when the pair of brake shoes 12 and 14 are expanded at the time of braking by the service brake, the strut 30 is moved to follow the brake shoe 12 on the opposite side with the expansion, and the adjustment lever is adjusted. 52 is rotated around the mounting shaft 56 with the relative movement of the strut 30 and the brake shoe 14. The amount of rotation of the adjust lever 52 corresponds to the amount of expansion of the brake shoes 12 and 14, that is, the shoe gap during non-braking, and when the amount of rotation exceeds a certain amount, the claw 52b at the tip engages the adjuster wheel 44. Then, the strut 30 is extended by rotating the adjuster wheel 44 in one direction A shown in FIG.
FIG. 2 is a sectional view of the adjuster wheel 44 as viewed from the screw shaft 48 side.

When the service brake is released, the brake shoe 14 and the second
As the strut 30 is moved rightward until it comes into contact with the strut member 42, the adjusting lever 5
2 is rotated clockwise back of the mounting shaft 56 against the urging force of the extension coil spring 58. As shown in FIG. 2, a saw tooth 44 t whose tip is inclined in the direction opposite to the one direction A is provided on the entire outer circumference of the adjuster wheel 44, so that when the brake is applied (expansion of the brake shoes 12 and 14). When the adjust lever 52 is rotated back in one direction A by being engaged with the claw portion 52b of the adjust lever 52 at the time of opening, the frictional rotation of the screw shaft 48 and the like occurs when the adjust lever 52 returns and rotates when braking is released. The return rotation of the adjuster wheel 44 is prevented by the resistance, and the claw 52b is
Over 4t.

On the other hand, between the adjuster wheel 44 of the strut 30 and the second strut member 42, a bimetal that is deformed with a temperature change due to a difference in thermal expansion coefficient between the two layers of the plate material that are integrally bonded is formed. The temperature-sensitive deformable member 60 configured as described above is provided. 3A and 3B are diagrams each showing the temperature-sensitive deformable member 60 alone, wherein FIG. 3A is a front view, and FIG.
(C) is a rear view, (d) is a cross-sectional view taken along line D-D of (a), corresponding to FIG. 1 (b), and (e) is a graph when the temperature rises.
It is a figure corresponding to (d). As is apparent from FIG. 3, the temperature-sensitive deformable member 60 has a bottomed cylindrical shape, and a through hole 64 having substantially the same size as the fitting shaft 50 is formed in the bottomed cylindrical shape 62. The adjuster wheel 44 is rotatably held between the second strut member 42 and the adjuster wheel 44 with the fitting shaft 50 inserted through the through hole 64. Further, the cylindrical portion 66 is located substantially concentrically on the outer peripheral side of the second strut member 42, and
Number of slits 68 in the axial direction is divided provided, by the tip of the opening side as the temperature rise is deformed so as to expanded toward the outer periphery, wherein its diameter d ₂ adjuster wheel 44 is larger than the outside diameter.
Thereby, the adjusting lever 52 is elastically deformed so that the adjusting lever 52 is engaged with the claw portion 52b when the adjusting lever 52 rotates, and the claw portion 52b is separated from the adjuster wheel 44 as shown by a dashed line in FIG. Alternatively, by changing the posture, the engagement with the adjuster wheel 44 is prevented, and the automatic adjustment of the shoe gap is prohibited. When the adjusting lever 52 is engaged with the slit 68, the temperature-sensitive deformable member 60 is rotated around the axis of the fitting shaft 50 with the rotation of the adjusting lever 52, but the adjuster wheel 44 is connected to the screw shaft 48 or the like. Rotational resistance due to friction of the motor prevents rotation. However, depending on the position of the slit 68, the adjusting lever 52 slides on the cylindrical portion 66. The slit 68 is formed up to an intermediate portion of the bottom 62. FIG.
The diameter dimension d ₁ at (d) at normal temperature is smaller than the outer diameter dimension of the adjuster wheel 44, and the automatic adjustment of the shoe gap by the engagement between the pawl portion 52b and the adjuster wheel 44 is allowed.

Such a temperature-sensitive deformable member 60 is provided,
When the temperature rises, the adjustment lever 52 and the adjuster wheel 44 are prevented from engaging with each other and the automatic adjustment of the shoe gap is prohibited, thereby preventing overadjustment due to excessive brake operation force. That is, the brake pedal is depressed with a large pedaling force, and the wheel cylinder 26
When the brake shoes 12 and 14 are pressed against the rotating drum 27 with a large pressing force, the inner diameter of the rotating drum 27 is enlarged, so that even if the lining 24 is not worn, the amount of rotation of the adjusting lever 52 is limited. The shoe gap is automatically adjusted beyond the fixed amount, and an over-adjustment in which the shoe gap during non-braking becomes too small may occur. The temperature of the drum brake 8 rises due to frictional heat between the brake shoes 12 and 14,
With the temperature rise, the temperature-sensitive deformable member 60 is deformed and engaged with the adjustment lever 52, and the automatic adjustment of the shoe gap is prohibited, thereby preventing such over-adjustment.

Here, the drum brake 8 of this embodiment is
With the fitting shaft 50 inserted through the through hole 64 of the temperature-sensitive deformable member 60, the second strut member 42 and the adjuster wheel 44 are fitted through the fitting shaft 50, and the Since the assembling of the deformable member 60 can be performed at the same time, the assembling of the temperature-sensitive deformable member 60 is easy, and since the fitting shaft 50 is inserted through the through hole 64, vibration of the wheel and the like can be prevented. Therefore, there is no danger that the temperature-sensitive deformation member 60 will fall off.

Further, in this embodiment, the bottomed cylindrical temperature-sensitive deformable member 60 is used, and is rotatably disposed between the second strut member 42 and the adjuster wheel 44. The attachment phase is free and the assembling work is further facilitated, and the temperature-sensitive deformable member 60 can be attached without changing the conventional strut 30 to prevent overadjustment.

Next, another embodiment of the present invention will be described. The temperature-sensitive deformable member 70 shown in FIG. 4 is made of a bimetal that is deformed with a change in temperature due to a difference in the coefficient of thermal expansion of the two-layer plate material that is integrally bonded.
A through-hole 72 having substantially the same size as that of the fitting shaft 50 is provided.
And a circular ring-shaped portion 74 positioned between the second strut member 42 and the adjuster wheel 44.
(B) provided integrally with the outer peripheral edge of the ring-shaped portion 74 and bent substantially at a right angle, and engaged with a notch groove provided on the outer peripheral portion of the second strut member 42,
A positioning projection 76 for preventing relative rotation between the ring-shaped portion 74 and the second strut member 42; and (c) a claw portion 52b of the adjust lever 52 in a state where the phase around the axis is positioned by the positioning projection 76. And an engaging portion 78 provided integrally with the outer peripheral edge of the ring-shaped portion 74 so as to be located in the vicinity of. The engaging portion 78 is bent at a substantially right angle to the ring-shaped portion 74, and is deformed in a direction away from the second strut member 42 as shown by a dashed line with an increase in temperature, so that the adjusting portion 78 is adjusted. When the lever 52 is rotated, the lever 52 is engaged with the claw portion 52b.
2 to prevent further rotation and inhibit automatic adjustment of the shoe gap. The ring-shaped portion 74 corresponds to a fitting plate portion, and the positioning projection 76 is provided at a mounting position where the engaging portion 78 can be engaged with the adjustment lever 52 around the axis of the fitting shaft 50. Corresponds to a positioning unit that positions the. FIG. 4 is a view showing an assembled state of the temperature-sensitive deformable member 70 and the second strut member 42. FIG.
(A) is a front view corresponding to (a), and (b) is a BB cross-sectional view of (a).

In this case, the ring-shaped portion 7 held between the second strut member 42 and the adjuster wheel 44
Since a single engaging portion 78 is provided on a part of the outer peripheral edge of the positioning member 4 and the engaging portion 78 is positioned by the positioning protrusion 76 so as to be in an assembled position where it can be engaged with the adjustment lever 52, Thermosensitive deformation member 60 of bottomed cylindrical shape of the embodiment
As compared with the above, the material yield is improved, the material cost is reduced, and the weight is reduced.

The temperature-sensitive deformable member 70 inhibits the rotation of the adjust lever 52 and inhibits the automatic adjustment of the shoe gap. For example, the temperature-sensitive deformable member 70 is curved at substantially the same curvature as the outer peripheral portion of the adjuster wheel 44. Is provided at the tip end of the engaging portion 78 so that the claw portion 52b can be moved while elastically deforming or changing its posture while slidingly contacting the arc-shaped portion, thereby allowing the adjustment lever 52 to rotate. The automatic adjustment of the shoe clearance may be prohibited by preventing engagement with the adjuster wheel 44.

The temperature-sensitive deformable member 80 shown in FIG. 5 is also integrally formed of a bimetal.
A through hole 82 having substantially the same size as that of the fitting shaft 50 is provided.
And a circular ring-shaped portion 84 positioned between the second strut member 42 and the adjuster wheel 44.
(B) provided at a part of the outer peripheral edge of the ring-shaped portion 84, bent substantially at a right angle, and extended in the axial direction along the outer peripheral surface of the second strut member 42, and with the rise in temperature. By being deformed in a direction away from the second strut member 42, the adjustment lever 52
And the claw portion 52b is engaged with the adjuster wheel 44.
A single engaging portion 86 that is separated from and disengaged,
(c) The engaging portion 86 is provided at the tip of the engaging portion 86 so as to form a substantially U-shape, and is engaged with the flat portion of the second strut member 42. 86 is an assembling position where the adjusting lever 52 can be engaged;
That is, the positioning section 88 is provided for positioning the temperature-sensitive deformable member 80 in a posture on the backing plate 10 side. The engaging portion 86 extends longer than the engaging portion 78 and can be engaged with the base end portion of the claw portion 52b. , And the automatic adjustment of the shoe gap is prevented while allowing the adjustment lever 52 to rotate. The ring-shaped portion 84 corresponds to a fitting plate portion. 5A is a sectional view corresponding to FIG. 1B, and FIG. 5B is a perspective view showing the temperature-sensitive deformable member 80 alone.

In this embodiment, the same effect as that of the embodiment shown in FIG. 4 is obtained, and in addition, the claw 52b is largely displaced by a slight deformation of the engaging portion 86 to adjust the adjuster wheel 44.
Can be disabled, so that the responsiveness is improved and the degree of freedom in selecting the bimetal is increased. The positioning portion 88 engages with a flat portion of the second strut member 42 which is engaged with the shoe web 20 of the brake shoe 14 and is crushed so as to be substantially perpendicular to the shoe web 20. The conventional second strut member 42 can be used as it is.

The temperature-sensitive deformable member 90 shown in FIG. 6 differs from the temperature-sensitive deformable member 80 in the positioning portion 92. That is, the positioning portion 92 of the temperature-sensitive deformable member 90 is substantially parallel to the engaging portion 86 on the outer peripheral edge of the ring-shaped portion 84 at a position separated from the engaging portion 86 by approximately 90 ° separately from the engaging portion 86. Notch 9 provided at the front end
By engaging the shoe 4 with the shoe web 20 of the brake shoe 14, the temperature-sensitive deformable member 90 is positioned at the assembly position. As described above, since the positioning portion 92 is provided separately from the engagement portion 86,
The deformation of the engaging portion 86 due to the rise in temperature and the action of preventing over-adjustment are stabilized. This is the same for the embodiment of FIG.

The temperature-sensitive deformable member 100 shown in FIG. 7 is also integrally formed of bimetal, and (a) is provided with a through hole 102 having substantially the same size as the fitting shaft 50 so that the fitting shaft 50 A circular ring-shaped portion 104 fitted and positioned between the second strut member 42 and the adjuster wheel 44; and (b) provided on a part of the outer peripheral edge of the ring-shaped portion 104, with the rise in temperature. Single engaging portion 1 which is engaged with the adjustment lever 52 by being deformed by
06 and (c) the ring-shaped portion 104 separately from the engagement portion 106.
The outer peripheral edge of the second strut member 42 is bent at a substantially right angle, and is engaged with a notch groove provided on the outer peripheral portion of the second strut member 42, so that the engaging portion 106 is adjusted around the axis of the fitting shaft 50. A positioning projection 108 for positioning the temperature-sensitive deformable member 100 at an assembly position at which the lever 52 can be engaged, that is, at a position on the backing plate 10 side.
And The engagement portion 106 is a ring-shaped portion 104.
Is bent substantially at right angles from the outer peripheral edge of the second strut member 42 and extends substantially parallel to the axial direction of the second strut member 42, and is bent outward by approximately 180 ° so as to form a substantially U-shape. When the opening side of the shape is deformed so as to expand, it is engaged with the adjustment lever 52, and as shown in FIG. 7 (b), the claw portion 52b is separated from the adjuster wheel 44 to disable the engagement. The automatic adjustment of the shoe gap is prevented while allowing the rotation of 52. The ring-shaped portion 104 corresponds to a fitting plate portion, and the positioning protrusion 108 corresponds to a positioning portion. Note that FIG.
(a) is a view corresponding to (b) of FIG.
FIG. 7B is an enlarged view of the vicinity of FIG. 7, and FIG. 7B shows a state in which the engaging portion 106 of the temperature-sensitive deformable member 100 is deformed.

In this embodiment, in addition to obtaining the same effects as those of the embodiment of FIG. 4, a U-shaped engaging portion 106 which is bent by approximately 180 ° is provided, and as the temperature rises, Since the opening side of the U-shape is deformed so as to expand, it can be engaged with the adjustment lever 52, and therefore, for example, the engaging portion 78 that is simply bent 90 ° as in the embodiment of FIG. The angle change accompanying the temperature change becomes larger as compared with the above, so that it is possible to dispose it in a small space while securing the displacement required for preventing the automatic adjustment of the shoe gap by the adjust lever 52.

The embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely one embodiment, and the present invention is based on the knowledge of those skilled in the art. Can be implemented.

[Brief description of the drawings]

FIG. 1 is a view showing a leading / trailing type drum brake to which the present invention is applied, (a) is a front view, and (b) is a view.
FIG. 4A is an enlarged cross-sectional view taken along line BB of FIG.

FIG. 2 is a sectional view of the adjuster wheel of FIG. 1 as viewed from a screw shaft side.

FIG. 3 is a diagram showing a temperature-sensitive deformable member provided alone in the drum brake of FIG. 1;

FIG. 4 is a diagram illustrating a main part of another embodiment of the present invention.

FIG. 5 is a view for explaining still another embodiment of the present invention.
1 is a sectional view corresponding to FIG. 1 (b), and FIG. 1 (b) is a perspective view showing the temperature-sensitive deformable member alone.

FIG. 6 is a view for explaining still another embodiment of the present invention;
FIG. 2 is an enlarged view of a portion corresponding to the temperature-sensitive deformable member in a view corresponding to FIG. 1B, and FIG. 2B is a perspective view showing the temperature-sensitive deformable member alone.

FIG. 7 is a view for explaining still another embodiment of the present invention.
FIG. 3B is a view corresponding to FIG. 1B and is an enlarged view of a portion near the temperature-sensitive deformable member, and FIG. 2B is a state in which an engaging portion of the temperature-sensitive deformable member is deformed with an increase in temperature. .

[Explanation of symbols]

8: Leading / trailing drum brake
12, 14: brake shoe 27: rotating drum
30: strut 40: first strut member 4
2: Second strut member 44: Adjuster wheel 50: Fitting shaft 52: Adjustment lever 5
4: Shoe gap automatic adjustment mechanism 60, 70, 80, 9
0, 100: Thermosensitive deformation member 62: Bottom 64, 7
2, 82, 102: Through hole 66: Cylindrical part 68:
Slits 74, 84, 104: Ring-shaped part (fitting plate part) 76, 108: Positioning protrusion (positioning part)
78, 86, 106: engaging part 88, 92: positioning part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenichi Hasegawa 10 Wakai-machi Michigami, Toyota City, Aichi Prefecture Inside Toyosei Brake Industry Co., Ltd. Address Toyosei Brake Industry Co., Ltd. (72) Inventor Tomoyuki Nogami 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3J058 AA03 AA07 AA13 AA17 AA24 AA28 AA33 AA37 BA58 BA64 DA04 DA33 FA01

Claims (4)

[Claims] 1. A pair of first strut members and a second strut member which are respectively non-rotatably engaged with one and the other of a pair of expandable brake shoes, and are disposed between the strut members. An adjuster wheel screwed to the first strut member and relatively rotatably fitted to the second strut member via a fitting shaft, and the approach of the pair of brake shoes during non-braking A strut that defines a position, and is rotatably disposed on one of the shoe webs of the pair of brake shoes, and is rotated in accordance with the amount of expansion of the pair of brake shoes during braking, An adjusting lever engaged with the adjuster wheel to rotate the adjuster wheel when the expansion amount exceeds a certain amount; The first strut member is separated from the adjuster wheel by the action of a screw with the rotation of the strut, the entire length of the strut is extended, and the approach position of the pair of brake shoes during non-braking is moved away from the rotating drum. A drum brake provided with a shoe gap automatic adjustment mechanism for automatically adjusting a shoe gap between the first and second shoe gaps, wherein a through-hole through which the fitting shaft can be inserted is provided and fitted to the fitting shaft. Rotation of the adjuster wheel by the adjust lever by engaging with the adjust lever by being held in a state sandwiched between the two strut members and the adjuster wheel and being deformed with a rise in temperature. A drum brake with an automatic shoe gap adjusting mechanism, comprising a temperature-sensitive deformable member for preventing the occurrence of a shock. 2. The temperature-sensitive deformable member has a bottomed cylindrical shape, and the through-hole is provided in a bottom of the bottomed cylindrical shape, and is rotated between the second strut member and the adjuster wheel. While freely disposed, the cylindrical portion located on the outer peripheral side of the second strut member is provided with a large number of slits in the axial direction, and the leading end on the opening side is increased in diameter toward the outer peripheral side as the temperature rises. The shoe gap automatic adjusting mechanism according to claim 1, wherein the diameter of the adjusting wheel is larger than that of the adjuster wheel to prevent the adjust lever from engaging with the adjuster wheel. Drum brake. 3. A flat plate-shaped member provided with the through-hole and fitted to the fitting shaft, and held between the second strut member and the adjuster wheel. A fitting plate portion, an engaging portion provided so as to extend from a part of an outer peripheral edge of the fitting plate portion, and being deformed with a rise in temperature to be engaged with the adjust lever; The shoe according to claim 1, further comprising: a positioning portion that positions the engagement portion so as to be in an assembled position where the engagement portion can be engaged with the adjustment lever around the axis of the shoe. Drum brake with automatic clearance adjustment mechanism. 4. A flat plate-shaped member provided with the through-hole and fitted to the fitting shaft, and held between the second strut member and the adjuster wheel. A fitting plate portion, which extends substantially parallel to the axial direction of the second strut member from the outer peripheral edge of the fitting plate portion, and is bent outward by approximately 180 ° so as to form a substantially U-shape. The U
2. The automatic shoe gap adjusting mechanism according to claim 1, further comprising: an engaging portion that is engaged with the adjust lever by being deformed so that the opening side of the U-shape is expanded. With drum brake.