JPH08338458A - Disk braking device and centroidal position setting method thereof - Google Patents

Abstract

PURPOSE: To enable it to easily realize such a structure as capable of preventing any tilting motion in a cylinder body of a floating type disk braking device. CONSTITUTION: In consideration of a plane comprising a vertical line L1 passing an opening end 6a and a vertical line L2 passing a tip 5a of the sliding part of a slide pin 5 (5A and 5B) as a main pin, the center of gravity G1 of a piston 11 is situated somewhat at the outside of two areas L1 to L2 in making the vertical line L1 a border in time both linings 7A and 8A being unworn (new articles), but it is situated at the inside of the areas L1 to L2 going beyond the vertical line L1 in time of maximum worn-out (just before replacement). Likewise, the center of gravity G2 of a cylinder body 4 is situated at the inside of the arears L1 to L2 in time of being unworn, but somewhat at the outside of the arears L1 to L2 going beyond the vertical line L1 in time of being maximum worn out. A moment size to be determined by the mass of the piston 11 and a distance between the center of gravity G1 in time of being maximum worn-out and the vertical line L1 and another moment size to be determined by the mass of the cylinder body 4, and a distance between the center of gravity G2 in time of being maximum worn-out and the vertical line L1 both are uniformized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake device and a method of setting a center of gravity thereof, and more particularly, in a so-called floating disc brake device, a structure capable of preventing tilting of a cylinder body supported by a torque member so as to be able to move forward and backward. Is easily realized.

[0002]

2. Description of the Related Art As a conventional disc brake device,
For example, there is one disclosed in JP-A-1-176822. That is, the disc brake device described in this publication is a so-called floating disc brake device, and the structure thereof will be briefly described. A pair of brake pads that sandwich the disc rotor from both sides are fixed to a torque member. Support to move forward and backward,
The torque member supports a caliper capable of moving forward and backward in the same direction as the direction of movement of the brake pad, and a fluid pressure actuator including a piston or the like for pressing one brake pad is provided in the caliper, and the other brake pad is The reaction force due to the pressing force of the fluid pressure actuator is used to press the caliper with the claw portion formed on the tip side.

In the disc brake device described in this publication, particularly, when the brake pad is in the state of a new product (not worn, initial position) to full wear (maximum wear, final position). , The center of gravity of the caliper
It is positioned within the sliding area of the member that guides the advance / retreat of the caliper, which enables stable support of the caliper without tilting it both when the brake is inoperative and when it is inactive. It was possible.

[0004]

However, when the disc brake device described in the above publication is actually used, it is necessary to significantly increase the weight of the caliper, as described in detail below. Therefore, various problems of inviting will occur. That is, during braking of the floating disc brake device, the piston inside the caliper moves to the disc rotor side in order to press the brake pad against the sliding surface of the disc rotor, and the caliper unit (cylinder The body) moves in the direction opposite to the moving direction of the piston. Even if the brake pad wears with use, the clearance between the brake pad and the disc rotor is kept constant by the action of the seal ring interposed between the peripheral surfaces of the piston and the cylinder hole. The center of gravity of the piston gradually moves toward the disc rotor side due to the wear of the cylinder, and the center of gravity of the cylinder body gradually moves in the direction opposite to the moving direction of the piston. Therefore, when considering the tilting of the caliper, it is necessary to consider both the center of gravity of the cylinder body and the center of gravity of the piston.

Here, in order to prevent the tilting of the cylinder body, the position of the center of gravity of the cylinder body and the piston as a whole is set so that the slide pin and the fitting hole are slidably guided (slide of the slide pin). It suffices to always be located within the area from the tip of the moving part to the opening of the fitting hole. However, since the cylinder body needs to accommodate the piston that presses one of the brake pads from the back side, when the disk rotor is the center, the portion that accommodates the piston has a large overhanging shape, and the cylinder body accommodates the piston. In the conventional piston described above, the cross-sectional shape passing through the axial center thereof is a U-shape that is open to the disk rotor side, so that the center of gravity of the piston is located in the vicinity of the farthest portion of the cylinder body from the disk rotor.

Therefore, the center of gravity of the conventional piston comes to be located outside the sliding region of the slide pin and the fitting hole, and between the vertical line passing through the end of the sliding region and the position of the center of gravity of the piston. Since a moment M ₁ having a distance of ₁ as an arm is generated, a moment M ₂ sufficient to cancel the moment M ₁ must be generated by the cylinder body in order to prevent tilting.

Now, as shown in FIGS. 9A and 9B showing the relationship between the center of gravity of the piston and cylinder body and the moments M ₁ and M ₂ generated in the piston and cylinder body, the initial position of the brake pad is shown. The center of gravity of the piston is positive from the vertical line (origin O) passing through the end of the sliding area (here, the side having the center of gravity of the piston with respect to the origin O is positive and the opposite is negative). If the maximum wear amount of the brake pad is 10 mm at the point A 60 mm apart,
The position of the center of gravity of the piston at the final position of the brake pad will move to point A ', which is 50 mm away from the vertical line on the positive side. Therefore, if the ratio of the mass of the cylinder body to the mass of the piston is 4: 1 which is a general ratio, a moment M of a magnitude that cancels the moment M ₁ generated when the center of gravity of the piston is at point A ′. _In order to generate ₂ , the center of gravity of the cylinder body at the final position of the brake pad must be at point B'at least 12.5 mm negative from origin O. Assuming that B'point and origin O
If the distance between and is less than 12.5 mm, the moment M ₁ becomes larger than the moment M ₂ , so that a force for inclining the moment is input to the cylinder body.

Therefore, since the movement amount of the cylinder body due to wear of the brake pad is equal to the movement amount of the piston, the center of gravity of the cylinder body at the initial position of the brake pad is at least 22.5 mm from the origin O to the negative side.
Must be set at a distant point B. However, as described above, the cylinder body has a shape in which the portion for accommodating the piston is largely projected to the positive side with respect to the origin O.
In order to set the center of gravity of the cylinder body to a predetermined position on the negative side, the claw side facing the back surface of the other brake pad must be made larger to increase its weight, but the weight of the cylinder body increases. If this happens, there is a problem that the unsprung weight of the vehicle is increased and the unsprung vibration is deteriorated. In order to move the center of gravity of the cylinder body away from the origin O to the negative side, it is conceivable to reduce the thickness of the portion of the cylinder body that accommodates the piston to reduce the weight, but an actual cylinder body is already possible. Since the weight has been reduced as much as possible, there is no room for cutting and it is not possible to adjust the position of the center of gravity due to the weight reduction.

Moreover, since the disc brake device is originally arranged in the space inside the wheel with a small space, considering the mounting state, the increase in weight of the cylinder body, which causes an increase in size, is a reality. It cannot be done easily. Even if the weight of the caliper is not increased, for example, the slide pin for guiding the movement of the cylinder body and the fitting hole are extended to expand the sliding area, and the position of the origin O which is the end of the sliding area is set to the piston. It is conceivable to reduce the moment M ₁ by approaching the position of the center of gravity of the slide pin. However, if the sliding area is widened, the slidability of the slide pin deteriorates and the braking feeling deteriorates. The length increases, which is a cost disadvantage. It is also possible to shorten the piston and reduce the weight of the portion of the cylinder body that accommodates the piston to bring the center of gravity of the cylinder body closer to the origin O to reduce the moment M _1. However, if the piston becomes shorter, braking is performed. The piston in the inside gets tired. Therefore, these possible measures cannot actually be adopted.

The present invention has been made by paying attention to the unsolved problems of the prior art as described above, and the torque of the cylinder body can be prevented without causing a significant increase in weight or size of the cylinder body. An object of the present invention is to provide a disc brake device that can easily realize a structure capable of preventing the tilting of a cylinder body supported by a member so as to be able to move forward and backward, and a method for setting the center of gravity thereof.

[0011]

In order to achieve the above object, the invention according to claim 1 has a pair of brake pads arranged so as to face each other so as to sandwich a disk rotor rotating with a wheel from both sides, and a pair of brake pads on the vehicle body side. A torque member that is fixed and supports the pair of brake pads so as to be movable back and forth in the disc rotor axial direction, a cylinder hole that faces the back side of the one brake pad, and a claw portion that faces the back side of the other brake pad. And a cylinder body supported by the torque member so as to be movable back and forth in the axial direction of the disk rotor through a pair of slide pins and a pair of fitting holes into which the slide pins are slidably fitted, and a forward and backward movement in the cylinder hole. A piston that can be accommodated, a seal ring that is interposed between the cylinder hole and the circumferential surface of the piston, the cylinder hole, and the piston. And a fluid pressure supplying / discharging means for supplying / discharging fluid pressure to / from the pressure chamber defined by the seal ring, in a vehicle body mounted state, the sliding area of the slide pin and the fitting hole. Is the maximum position, the final position is the position where the sliding area of the slide pin and the fitting hole is the minimum when the vehicle is mounted,
Of the pair of slide pins and the fitting hole, the clearance between the peripheral surfaces of the one slide pin and the fitting hole, which is located vertically upward when the vehicle body is mounted, is the clearance between the peripheral surfaces of the other slide pin and the fitting hole. The vertical line passing through the tip of the sliding portion of the one slide pin and the vertical line passing through the opening end of the one fitting hole, and adjusting the position of the center of gravity of the cylinder body. By providing a cylinder body center of gravity adjusting means and a piston center of gravity adjusting means for adjusting the position of the center of gravity of the piston, the center of gravity of the piston projected onto a plane including the two vertical lines is the initial position It is located outside the area sandwiched by two vertical lines and inside the area at the final position, and the weight of the cylinder body projected on the plane is A position is located on the opposite side of the center of gravity of the piston at the initial position and the final position, with a first vertical line between the two vertical lines being closer to the center of gravity of the piston at the initial position. I decided to do it.

According to a second aspect of the present invention, in the disc brake device according to the first aspect of the present invention, the mass of the piston is between the center of gravity of the piston at the final position and the first vertical line. The magnitude of the moment determined by the distance is equal to or greater than the magnitude of the moment determined by the mass of the cylinder body and the distance between the center of gravity of the cylinder body at the final position and the first vertical line. The distance between the center of gravity of the cylinder body at the final position and the first vertical line and the distance between the center of gravity of the piston and the first vertical line are adjusted by the cylinder body center of gravity adjusting unit and the piston center of gravity adjusting unit. .

According to a third aspect of the invention, in the disc brake device according to the first or second aspect of the invention, the cylinder body center of gravity adjusting means is added to the claw portion side of the cylinder body. And the added mass. According to a fourth aspect of the invention, in the disc brake device according to the first to third aspects of the invention, the cylinder body center of gravity adjusting means is added to an opening for heat dissipation formed in the cylinder body. The additional mass was used.

Further, the invention according to claim 5 is the disc brake device according to any one of claims 1 to 4, wherein the sectional shape passing through the axial center of the piston is U-shaped.
The piston center-of-gravity adjusting means has a structure in which the U-shaped open side of the piston faces the bottom surface side of the cylinder hole. According to a sixth aspect of the invention, in the disc brake device according to the fifth aspect of the invention, the inner peripheral surface of the piston is tapered so that the bottom surface side of the cylinder hole is expanded.

Further, the invention according to claim 7 is the disk brake device according to any one of claims 1 to 6 above, wherein, of the surfaces of the piston that come into contact with the brake pad, the disk rotor forward rotation direction inflow side. The end was cut out. On the other hand, in order to achieve the above-mentioned object, the invention according to claim 8 is such that a pair of brake pads arranged to face each other so as to sandwich a disk rotor rotating with a wheel from both sides, and the pair of brake pads fixed to the vehicle body side. A pair of torque members for supporting the pad so as to be movable back and forth in the axial direction of the disc rotor, a cylinder hole facing the back side of the one brake pad, and a claw portion facing the back side of the other brake pad are provided. A slide pin and a cylinder body supported by the torque member so as to be movable back and forth in the axial direction of the disk rotor through a pair of fitting holes into which the slide pin is slidably fitted, and a piston accommodated so as to be movable back and forth in the cylinder hole. A seal ring interposed between the cylinder hole and the circumferential surface of the piston, and the cylinder hole, the piston and the seal ring Fluid pressure supply / discharge means for supplying / discharging a fluid pressure to / from the defined pressure chamber, wherein one slide pin of the pair of slide pins and the fitting hole is positioned on the upper side in the vertical direction when the vehicle body is mounted, and In the method of setting the center of gravity of a disc brake device, wherein the clearance between the peripheral surfaces of the fitting hole is smaller than the clearance between the other slide pin and the peripheral surface of the fitting hole, the slide pin and the fitting are fitted in the vehicle body mounted state. The maximum position of the sliding area of the dowel hole is the initial position, and the minimum position of the sliding area of the slide pin and the fitting hole is the final position when the vehicle is mounted. Assuming a vertical line passing through and a vertical line passing through the opening end of the one fitting hole, the position of the center of gravity of the piston projected on a plane including the two vertical lines is at the initial position. The center of gravity of the piston is set so that it is outside the area sandwiched by the two vertical lines and inside the area at the final position, and the center of gravity of the cylinder body is projected on the plane. Of the two vertical lines, the first vertical line close to the center of gravity of the piston at the initial position is sandwiched so that the initial position and the final position are opposite to the position of the center of gravity of the piston. In addition, the center of gravity of the cylinder body is set.

According to a ninth aspect of the present invention, in the method for setting the center of gravity of the disc brake device according to the eighth aspect, the mass of the piston, the center of gravity of the piston at the final position, and the first position. The magnitude of the moment determined by the distance between the vertical lines is equal to or greater than the magnitude of the moment determined by the mass of the cylinder body, the center of gravity of the cylinder body at the final position, and the distance between the first vertical lines. In addition, the distance between the center of gravity of the cylinder body and the first vertical line at the final position and the distance between the center of gravity of the piston and the first vertical line are set.

[0017]

According to the first aspect of the invention, the clearance between the peripheral surface of the one slide pin located vertically upward and the fitting hole is the other slide pin located vertically downward. Since it is smaller than the clearance between the peripheral surfaces of the holes, the load on the cylinder body will be supported by the torque member via one slide pin,
The slide pin located on the upper side in the vertical direction is a so-called main pin, and the slide pin located on the lower side in the vertical direction is a so-called sub pin.

By providing the cylinder body center of gravity adjusting means and the piston center of gravity adjusting means, the center of gravity of the cylinder body and the center of gravity of the piston are adjusted appropriately. Therefore, the vertical line passing through the tip of the sliding portion (the portion that slides with the fitting hole) of the slide pin that is the main pin,
Assuming a vertical line passing through the open end of the fitting hole where the main pin fits, the center of gravity of the piston projected on the plane including these two vertical lines changes from the initial position of the brake pad to the final position. One vertical line in between (first vertical line)
Therefore, the moment determined by the mass of the piston and the distance between the first vertical line and the position of the center of gravity of the piston becomes extremely small.

On the other hand, the center of gravity of the cylinder body projected on a plane including two vertical lines also exceeds the first vertical line between the initial position and the final position of the brake pad, but the initial position and the final position are not included. The position is on the opposite side of the side where the center of gravity of the piston is located with the first vertical line sandwiched therebetween. Therefore, the moment determined by the mass of the cylinder body and the distance between the first vertical line and the position of the center of gravity of the cylinder body becomes extremely small.

From the above, since the moment for tilting the cylinder body containing the piston is always kept small, the possibility that the cylinder body tilts is reduced. Particularly, in the invention according to claim 2, since the moment generated by the cylinder body at the final position is canceled by the moment generated by the piston, the initial position of the brake pad is provided on the cylinder body in the state where the piston is housed. From the to the final position, no tilting occurs.

In the invention according to claim 3, the position of the center of gravity of the cylinder body is adjusted to the claw portion side by the additional mass added to the claw portion side of the cylinder body. The center of gravity of the cylinder body is adjusted to the claw side by the additional mass added to the heat dissipation opening of the cylinder body, but the center of gravity of the cylinder body is closer to the cylinder hole side than before. Therefore, the added mass can be small.

Further, in the invention according to claim 5, when the piston is accommodated in the cylinder hole with the side opened in the U-shaped cross section facing the bottom surface side of the cylinder hole, the relatively light portion is It is located on the bottom surface side of the cylinder hole, and the relatively heavy portion is located on the opening end side of the cylinder hole, and the center of gravity of the piston is closer to the opening end side. When the inner peripheral surface of the piston is tapered as in the invention according to claim 6, the position of the center of gravity of the piston comes to be located closer to the opening end side of the cylinder hole. Can be set at a predetermined position more easily as in the invention according to claims 1 and 2. Moreover, since the volume of the hollow portion of the piston is reduced, the amount of oil or the like that is supplied to and discharged from the pressure chamber for adjusting the fluid pressure is reduced.

Further, according to the invention of claim 7, when the disc rotor rotates in the forward direction, a moment is generated to wind the turn-in side portion of the brake pad in the disc rotor normal rotation direction. If the disc rotor turning-in side end of the surface that contacts with is notched, the disc rotor forward rotation-direction turning-in side end of the back surface of the brake pad will not receive the pressing force of the piston and the back surface of the brake pad will Since the pressing force received on the delivery side is larger than that on the delivery side, a moment in the opposite direction to the above-mentioned moment to be involved is generated.

When the center of gravity positions of the piston and the cylinder body of the disc brake device are set by the invention according to claim 8, the mass of the piston and the first vertical line and the piston are set in the same manner as in the invention according to claim 1. The moment determined by the distance between the centers of gravity is extremely small,
Since the moment determined by the mass of the cylinder body and the distance between the first vertical line and the position of the center of gravity of the cylinder body is extremely small, the moment to tilt the cylinder body with the piston housed is always small. Since it is maintained, the possibility that the cylinder body tilts is reduced.

Then, when the center of gravity positions of the piston and the cylinder body of the disc brake device are set by the invention according to claim 9, as in the invention according to claim 2,
Since the moment generated by the cylinder body at the final position is canceled by the moment generated by the piston, the cylinder body containing the piston does not tilt.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing a first embodiment of the present invention, in which the disc brake device 1 according to the present invention is applied to a vehicle braking device. First,
The configuration will be described. The disc brake 1 is, as shown in FIG. 1 which is a partially cutaway perspective view showing the mounting state, the disc rotor 1 at a position in front of the disc rotor 2 rotating integrally with the wheels 2A. 2 has a torque member 3 fixed to the vehicle body side so as to approach from the outside in the radial direction. The torque member 3 has a disk rotor axial direction (direction along the rotation axis of the disk rotor 2, hereinafter,
This is called the rotor axial direction. ) Cylinder body 4
Is supported.

Specifically, at both ends of the torque member 3 in the vertical direction, two tubular portions 3A, 3B extending in the rotor axial direction along the outer peripheral surface of the disk rotor 2 are provided, and the tubular portions 3A, 3A, 3B are provided. In the cylinder body 4 which straddles the disk rotor 2 between 3B, an arm portion 4 extending in the vertical direction to a position facing the tip end portions of the cylindrical portions 3A and 3B.
A and 4B are integrally provided. Then, as shown in FIG. 2 (however, the disc rotor 2 is omitted in FIG. 2) which is a partially cutaway front view of the disc brake device 1, the arm portions 4A and 4B of the disc rotor 2 side are shown. The facing surface has a pair of slide pins 5 extending in the rotor axial direction.
A and 5B are fixed, and these slide pins 5A,
5B is a fitting hole 6A, 6A formed in the cylindrical portion 3A, 3B.
These slide pins 5 are slidably fitted to B
The cylinder body 4 can advance and retreat in the rotor axial direction with respect to the torque member 3 via A and 5B and the fitting holes 6A and 6B. The slide pins 5A, 5B and the fitting holes 6A, 6B are lubricated with grease, and a bellows cylindrical elastic member is provided between the tip portions of the tubular portions 3A, 3B and the arm portions 4A, 4B. A dust boot 4a composed of a body is provided.

Further, in this disc brake device 1, the clearance between the peripheral surfaces of the one slide pin 5A and the fitting hole 6A, which are positioned on the upper side in the vertical direction when mounted on the vehicle body, is the lower side in the vertical direction. It is smaller than the clearance between the peripheral surfaces of the other slide pin 5B positioned at and the fitting hole 6B. Therefore, when the cylinder body 4 moves back and forth with respect to the torque member 3, both slide pins 5A, 5
Although guided by B and the fitting holes 6A and 6B, the weight of the cylinder body 4 is supported on the torque member 3 side via the one slide pin 5A and the fitting hole 6A. That is, the slide pin 5A located on the upper side in the vertical direction
Is a so-called main pin, and the slide pin 5B located on the lower side in the vertical direction is a so-called sub pin.

Further, the torque member 3 is supported by a pair of brake pads 7 and 8 which are arranged so as to face each other so as to sandwich the disk rotor 2 from both sides and which face both frictional sliding surfaces of the disk rotor 2. These brake pads 7 and 8 are linings 7 located on the disc rotor 2 side.
A and 8A and a backing metal 7B, 8B fixed to the back side thereof are overlapped with each other, and the outer peripheral portions of the backing metal 7B, 8B wider in the length and width than the linings 7A, 8A have an anti-rattle spring (not shown). It is supported by the torque member 3 so as to be movable back and forth in the rotor axial direction.

The cylinder body 4 faces the back side (the side to which the lining 7A is not fixed) of the back metal 7B of the one brake pad 7 arranged on the inner side in the vehicle width direction (equal to the rotor axial direction). A base portion 4C, and two claw portions 4D that are separated in the vertical direction and that face the back surface of the backing metal 8B of the other brake pad 8 that is disposed on the outer side in the vehicle width direction are formed. Those base 4C
And the surface of the claw portion 4D that faces the disc rotor 2 side,
The pair of brake pads 7 and 8 are sandwiched at a predetermined distance from the back side thereof.

In the base portion 4C of the cylinder body 4, there is formed a cylinder hole 10 which is open on the brake pad 7 side. The axis of the cylinder hole 10 coincides with the axial direction of the rotor, and the cylinder hole 10 houses a piston 11 having a cylindrical appearance. Specifically, a groove 10a continuous in the circumferential direction is formed on the inner peripheral surface of the cylinder hole 10, and a seal ring 10A made of a ring-shaped elastic body having a substantially rectangular cross section is arranged in the groove 10a. The inner peripheral surface of the seal ring 10A is in close contact with the outer peripheral surface of the piston 11.

The piston 11 has a substantially U-shaped cross section passing through the axial center thereof, and the open side of the U-shape faces the bottom surface side of the cylinder hole 10 (right side in FIG. 2). It is housed in 10. However, the piston 11
The inner peripheral surface 11A has a taper shape in which the bottom surface side of the cylinder hole 10 expands, and the tip portion 11B of the piston 11 that abuts the back metal 7B of the brake pad 7 is thicker than the peripheral portion. As a result, the center of gravity G ₁ of the piston 11 is located on the opening end side of the cylinder hole 10. The detailed position of the center of gravity G ₁ will be described later. A dust boot 10b made of a bellows cylindrical elastic body is provided between the outer peripheral surface of the tip portion 11B of the piston 11 and the inner peripheral surface of the opening end side of the cylinder hole 10A.

The bottom surface of the cylinder hole 10, the inner peripheral surface 11A of the piston 11, and the seal ring 10A define a hydraulic chamber 12 as a pressure chamber.
Reference numeral 2 is connected to a known master cylinder (not shown) via an oil passage 12A, a pipe 12B, etc., so that a hydraulic pressure corresponding to the stepping force of the brake is supplied into the hydraulic chamber 12.

The setting of the center of gravity G ₁ of the piston 11 and the center of gravity G ₂ of the cylinder body 4 will now be described. A slide pin 5A as a main pin for supporting the weight of the cylinder body 4 on the torque member 3 and a fitting hole 6A. The sliding area between the open end portion 6a of the fitting hole 6A and the tip 5a of the sliding portion at the initial position of sliding on the inner peripheral surface of the fitting hole 6A of the shaft portion of the slide pin 5A. Since it is a space, the opening end 6
A vertical line L ₁ passing through a and a vertical line L ₂ passing through the tip 5 a are assumed, and a plane including these vertical lines L ₁ and L ₂ is considered.
In this case, since FIG. 2 is a front view of the disc brake device 1 in which the vertical direction extends vertically, this FIG.
It corresponds to a plane including ₁ and L ₂ .

In this plane, the center of gravity of the entire cylinder body 4 including the piston 11 is always the vertical line L ₁
If it is in a region sandwiched by L ₂ and L ₂ , the tilting of the cylinder body 4 should be prevented, and the center of gravity of the entire cylinder body 4 is the center of gravity G _{1 of the} piston 11 and the cylinder body 4
It can be considered separately from the center of gravity G _{2 of a} single body. Of these, the center of gravity G _{1 of the} piston 11 is located slightly outside the region L ₁ -L _{2 with} the vertical line L ₁ as a boundary at the initial position (when new) of the linings 7A, 8A of the brake pads 7, 8. The final position of the linings 7A and 8A (just before replacement)
Region L ₁ -L ₂ beyond the vertical line L ₁ on the near side.
It is located inside the. Therefore, in this embodiment, the vertical line L ₁ corresponds to the first vertical line.

On the other hand, the center of gravity G ₂ of the cylinder body 4 is located inside the region L ₁ -L _{2 at} the initial position, and slightly over the vertical line L ₁ at the final position and slightly in the region L ₁ -L ₂ . It is located outside. The magnitude of the moment M ₁ determined by the mass of the piston 11 and the distance between the center of gravity G ₁ and the vertical line L ₁ at the final position, and the mass of the cylinder body 4 and the center of gravity G ₂ and the vertical line L _{1 at the} final position. The magnitude of the moment M ₂ determined by the distance is equal.

To explain this concretely, for example, the center of gravity G
_As shown in FIGS. 3A and 3B showing the relationship between the positions of ₁ and G ₂ and the moments M ₁ and M ₂ , the center of gravity G _{1 at the} initial position is
Is only 2mm from the origin O is the position where vertical line L ₁ passes through the region L ₁ -L ₂ (left side of FIG. 3 origin O area L
It is inside _1- L ₂ . ), The center of gravity G _{1 at the} final position is located at a point A outside the
As a result of moving to the left in FIG. 2 by 10 mm which is the maximum amount of wear, the point is located at the point A ′ that has entered the inside of the region L ₁ -L _{2 by} 8 mm from the origin O.

If the ratio of the mass of the piston 11 to the mass of the cylinder body 4 is set to 1: 4, the moments M ₁ and M ₂ generated at the final position are equal in magnitude to the final position. The center of gravity G ₂ may be located at a point B ′ separated from the origin O by 2 mm outside the region L ₁ -L ₂ . Therefore, the center of gravity G _{2 at the} initial position is 8 mm from the origin O.
Therefore, it is located at the point B that has entered the inside of the region L ₁ -L ₂ .

Here, in the present embodiment, the cylinder body 4
4A is a plan view of the cylinder body 4 alone and FIG. 4 is a side view in which the arms are omitted.
As shown in (b), the additional mass 4E added to the claw portion 4D side of the cylinder body 4 is used. Although not shown in FIG. 2, 4G shown in FIG. 4A is an opening for improving the heat dissipation of the disc rotor 2.

Next, the operation of this embodiment will be described. That is,
At the initial position where the linings 7A, 8A of the brake pads 7, 8 are not worn, the center of gravity G _{1 of the} piston 11 is shown in FIG.
The center of gravity of the cylinder body 4 located at the point A in FIG.
Since it is located at the point B in (a), the moment M ₁ generated around the origin O by the mass of the piston 11 and the moment M ₂ generated around the origin O by the mass of the cylinder body 4 are in opposite directions. The ratio M ₁ : M ₂ of the size is _{1 because} the center of gravity of the cylinder body 4 is 4 times farther and the cylinder body 4 is 4 times heavier.
It becomes 6: 1. Therefore, due to the difference between the moments M ₁ and M ₂ , the entire cylinder body 4 has an origin O (open end 6).
Although it is going to rotate counterclockwise in FIG. 2 about a), such rotation is caused by the slide pin 5A and the fitting hole 6
Since the cylinder body 4 is supported by the portion between the regions L _{1 and} L _{2 of} A, the cylinder body 4 is not tilted (physically impossible).

On the other hand, when the driver depresses the brake pedal, the hydraulic pressure increased by the master cylinder or the like is supplied into the hydraulic chamber 12, so that the piston 11 is displaced by the hydraulic pressure in the direction approaching the disc rotor 2. . Then, the tip end surface of the piston 11 presses the back metal 7B of the brake pad 7, so that the brake pad 7 is displaced toward the disk rotor 2 and its lining 7A is pressed against the friction sliding surface of the disk rotor 2.

When the piston 11 is further displaced toward the disc rotor 2 side by the hydraulic pressure in the hydraulic chamber 12 from this state, the cylinder body 4 itself is displaced by the piston 11 by the reaction force caused by the brake pad 7 pressing the disc rotor 2. Since the claws 4D, 4D are displaced in the direction approaching the disc rotor 2 as well, the back metal 8B of the brake pad 8 is pressed.
The brake pad 8 is displaced toward the disc rotor 2, and the lining 8A is brought into sliding contact with the friction sliding surface of the disc rotor 2.

Then, such brake pads 7, 8
Since the operation of is performed within an extremely short time, when the brake pedal is depressed, the disc rotor 2 is sandwiched from both sides by the brake pads 7 and 8 almost at the same time, and the space between the brake pads 7 and 8 and the disc rotor 2 is reduced. Friction of the disk rotor 2 converts the rotational force of the disk rotor 2 into heat for braking. The braking torque input from the disc rotor 2 to the brake pad is supported on the vehicle body side via the torque member.

When the piston 11 moves during braking, elastic deformation occurs in the seal ring 10A that is in close contact with the outer peripheral surface of the piston 11, so that the depression of the brake pedal is released and the hydraulic pressure in the hydraulic chamber 12 is discharged. Then, the piston 11 is separated from the disc rotor 2 by the restoring force of the seal ring 10A, the cylinder body 4 also moves in the direction opposite to the moving direction of the piston due to the disappearance of the pressing force of the piston 11, and the brake pads 7 and 8 are used. The pinched state of the disk rotor 2 is eliminated, and the braking ends.

When such braking is repeatedly performed, the friction sliding surfaces of the linings 7A and 8A of the brake pads 7 and 8 are worn, so that the clearance between the linings 7 and 8 and the disc rotor 2 is expanded. become. Then, since the moving distance of the piston 11 during braking becomes long, slippage occurs between the piston 11 and the seal ring 10A. However, since the elastic deformation amount of the seal ring 10A is constant, it is The return amounts of the piston 11 and the cylinder body 4 are constant. Therefore, the clearance between the lining 7A, 8A of the brake pad 7, 8 and the disc rotor 2 is kept constant even if the lining 7A, 8A is worn.

However, when the linings 7A and 8A are worn, the center of gravity G _{1 of the} piston 11 moves leftward in FIG. 2 and the center of gravity G ₂ of the cylinder body 4 moves rightward in FIG. 2 by the amount of wear. That is, in the case of FIGS. 3A and 3B,
The center of gravity G ₁ moves from the point A to the point A ′, and the center of gravity G ₂ moves from the point B to the point B ′. Then
Moment M ₁ is the center of gravity G ₁ is gradually reduced until reaching the vertical line L _1, and gradually increases is simultaneously rotating direction exceeds the vertical line L ₁ is opposite. On the other hand, the moment M ₂ gradually decreases until the center of gravity G ₂ reaches the vertical line L ₁ , and at the same time when the center of gravity G ₂ exceeds the vertical line L ₁ , the rotation direction reverses and gradually increases.

In this case, when the center of gravity G ₁ reaches the vertical line L ₁ and the moment M ₁ becomes "0", the center of gravity G ₂ is in the region L ₁ -L ₂ , so that the cylinder body 4 is moved to the position shown in FIG. A moment M ₂ that tries to rotate counterclockwise is generated. Therefore, while the center of gravity G ₁ extends from the point A to the origin O, the cylinder body 4 as a whole does not tilt. When the center of gravity G ₁ crosses the vertical line L ₁ and enters the region L ₁ -L ₂ due to wear, the moment the center of gravity G ₂ reaches the origin O is due to both moments M ₁ and M ₂ of the cylinder body. 4 is shown in FIG.
Since the cylinder body 4 tries to rotate in the counterclockwise direction, the tilting of the entire cylinder body 4 does not occur.

As the wear advances, the center of gravity G ₂ becomes the vertical line L.
_If you go over the area L ₁ -L ₂ beyond ₁ , this time,
Since the direction of the moment M ₂ is opposite, the moment M ₂ tends to rotate the cylinder body 4 clockwise in FIG. However, the moment M ₂ after the center of gravity G ₂ exceeds the vertical line L ₁ is moment M ₁ when it reaches the point B ′.
And the moment M ₁
It has the following size. Therefore, even while the center of gravity G ₂ reaches from the origin O to the point B ′, the cylinder body 4 tries to rotate counterclockwise in FIG. 2 due to the difference between the moments M ₁ and M _{2, so} that the entire cylinder body 4 still has No tilting occurs.

As described above, with the structure of this embodiment, the cylinder body 4 tilts regardless of whether the linings 7A, 8A of the brake pads 7, 8 are in the initial position to the final position. Can be prevented. Then, if the tilting of the cylinder body 4 can be prevented, the slide pin 5
Since A and 5B do not incline with respect to the fitting holes 6A and 6B, the cylinder body 4 moves forward and backward smoothly, and the braking feeling is not impaired.

Moreover, as a result of locating the center of gravity G _{1 of the} piston 11 on the opening end side of the cylinder hole 10 and changing the positional relationship of the centers of gravity G ₁ and G ₂ with respect to the vertical line L ₁ between the initial position and the final position, Center of gravity G of cylinder body 4
₂ can be set to a position much closer to the origin O than before. Then, the cylinder body 4 becomes the base 4C.
Even if the disk rotor 2 has a shape that greatly extends toward the inside of the vehicle by that amount, the center of gravity G ₂ needs to be set near the center of the cylinder body 4 in the axial direction of the rotor. Center of gravity G with mass 4E added
There is no need to set the position of ₂ . That is, as shown in FIG.
The broken line in (b) is the appearance of the cylinder body 4 when the additional mass 4E is not added, and is shown in FIGS. 4 (a) and 4 (b).
An alternate long and short dash line indicates an additional mass when the center of gravity G ₂ of the cylinder body 4 needs to be set at a position far from the origin O in the conventional disc brake device, and as can be seen by comparing these, In this embodiment, since the cylinder body 4 is not significantly increased in weight or size,
The unsprung weight of the vehicle is not significantly deteriorated due to a large increase in unsprung weight, and the disc brake device 1
It is also very advantageous in arranging in the space inside the wheel with a small space.

In this embodiment, the piston 1
Since the open side of 1 is directed to the bottom side of the cylinder hole 10, the air can be easily removed when the vehicle is assembled, and the center of gravity G ₁ can be easily located at the opening end side of the cylinder hole 10. In particular, since the inner peripheral surface 11A of the piston 11 is tapered so that the opening side is expanded and the tip end portion 11B is thick, the center of gravity G ₁ can be extremely easily positioned on the opening end side of the cylinder hole 10. You can do it.

Further, the inner peripheral surface 11A of the piston 11 is opened.
If the side is tapered so that the diameter increases, the inside of the piston 11
Since the volume becomes smaller, the volume of the hydraulic chamber 12 is correspondingly reduced.
It will be smaller and use less brake fluid.
There are also advantages. The moment M at the final position₁Over
And M₂If the size of is equalized as in this embodiment,
Center of gravity G of cylinder body 4 at fixed position₂The most vertical
Line L ₁The center of gravity G₂Adjustment is most acceptable
It will be easy. However, the moment M at the final position₁Over
And M₂The size relationship of M₁≧ M₂Then cylinder body
Since tilting of No. 4 can be prevented, the example shown in FIG.
Center of gravity G of cylinder body 4 at final position₂Is more than point B
Area L from the origin O side₁-L₂At the position where it goes inside
There may be.

Here, in the present embodiment, the cylinder body center of gravity adjusting means is constituted by the additional mass 4E, and the piston 11 having a U-shaped cross section is inserted into the cylinder hole 10 with its open side facing the bottom surface side of the cylinder hole 10. The piston center-of-gravity adjusting means is configured by the housed structure, the structure in which the inner peripheral surface 11A of the piston 11 is tapered, and the structure in which the tip portion 11B is thicker than the peripheral portion, and the oil passage 12A, the pipe 12B, and a master not shown A fluid pressure supply / discharge means is constituted by the cylinder.

FIGS. 5 (a) and 5 (b) are views showing a second embodiment of the present invention, and FIG. 5 (a) is an enlarged sectional view of an essential part of this embodiment, and FIG. 5 (b). [Fig. 3] is a view from the direction of arrow A of the same (a). Since the overall structure is the same as that of the first embodiment, the illustration and description thereof will be omitted, and the same members and parts will be denoted by the same reference numerals and the duplicate description thereof will be omitted.

That is, in this embodiment, the piston 11
Of the surfaces that come into contact with the back metal 7B of the brake pad 7 of
In the normal rotation direction of the disk rotor (the rotation direction of the disk rotor when the vehicle is moving forward, referred to as the normal rotation direction of the rotor), the entry side (the side in which the disk rotor 2 enters the disk brake device 1 during normal rotation) 5 is the upper side.) A step portion 11C is formed by notching the end portion. Other configurations are similar to those of the first embodiment.

When braking in a normal disc brake device, the brake pads 7 and 8 receive a frictional force from the frictional sliding surface of the disc rotor 2 as schematically shown in FIG. Generate moments M ₃ and M ₄ that try to wind the entry side portion in the normal direction of the disc rotor, which accelerates the partial wear of the brake pads 7 and 8 and hasten the replacement time. become.

However, according to the structure of this embodiment, since the end portion of the backing plate 7B of the brake pad 7 on the advancing side is not subjected to the pressing force of the piston 11, the pressing force received by the brake pad 7 is on the advancing side. Is larger than that on the inflow side, which causes a moment in the opposite direction to the moment M ₃ ,
It is possible to reduce the effect of the moment M ₃ being small or disappearing, which promotes partial wear of the brake pad 7. It should be noted that, although not particularly shown, also with respect to the claw portion 4D of the cylinder body 4, as with the piston 11 of the present embodiment, the force pressing the brake pad 8 is larger on the squeeze side than on the squeeze in side. If, for example, a part of the brake pad 8 is partially notched, a moment in the direction opposite to the moment M ₄ is also generated, so that partial wear of the brake pad 8 can be reduced.

Other functions and effects are similar to those of the first embodiment. FIG. 7 is a diagram showing a third embodiment of the present invention and is an enlarged sectional view of a main part of the configuration. Since the overall structure is the same as that of the first embodiment, the illustration and description thereof will be omitted, and the same members and parts will be denoted by the same reference numerals and the duplicate description thereof will be omitted.

That is, in this embodiment, the piston 11
Contrary to the first embodiment, the cylinder is accommodated in the cylinder hole 10 with its open side having a U-shaped cross section facing the brake pad 7 side. In addition, the inner peripheral surface 11A of the piston 11
Is not particularly tapered. Then, on the inner surface side of the opening end portion of the piston 11 facing the brake pad 7 side, a ring-shaped mass body 1 as piston gravity center adjusting means.
5 is fixed so that the center of gravity of the piston 11 is located near the opening end of the cylinder hole 10 as in the first embodiment. The centers of gravity of the piston 11 and the cylinder body 4 are set to the same positions as in the first embodiment. Other configurations not shown are the same as those in the first embodiment.

With this structure, the hydraulic chamber 12 is
Since it is defined by the inner surface of the cylinder hole 10, the outer surface of the piston 11, and the seal ring 10A, the volume of the hydraulic chamber 12 is significantly smaller than that of the first embodiment, and therefore the brake fluid The amount used is small, which is advantageous in terms of cost. Further, when the inside of the piston 11 is not used as the hydraulic chamber 12 as in the present embodiment, the brake fluid should be separated from the sliding portions of the disc rotor 2 and the brake pad 7 that generate friction heat during braking. It is also advantageous in terms of heat resistance of brake fluid.

The configuration of the present embodiment is also advantageous over the configuration of the first embodiment in that there are fewer changes when applied to the existing disc brake device. Other functions and effects are similar to those of the first embodiment. In each of the above embodiments, the positions of the center of gravity G _{1 of the} piston 11 and the center of gravity G ₂ of the cylinder body 4 are set in detail as shown in FIG. 3, but the position is not limited to this, and the piston is not limited to this. If the center of gravity G ₁ of 11 is located on the opening end side of the cylinder hole 10, the moment M ₁ becomes extremely small. Therefore, the center of gravity G ₂ of the cylinder body 4 is always in the region from the initial position to the final position. Even within L ₁ -L ₂ ,
The tilting of the entire cylinder body 4 can be reduced or prevented.

In the constructions of the first and second embodiments, the opening of the piston 11 facing the bottom surface of the cylinder hole 10 is thin enough to withstand the internal pressure of the hydraulic chamber 12 during braking. If the lid member is used, the amount of brake oil used is reduced and it is advantageous in terms of heat resistance of the brake oil, as in the third embodiment. Furthermore, the piston 11
The structure for arranging the center of gravity of the above position on the opening end side of the cylinder hole 10 is not limited to the configuration of each of the above embodiments,
For example, if a shim plate or the like that is inserted to prevent squeal of the brake pad 7 is coupled to the tip of the piston 11 and the load of the brake pad 7 or the shim plate is applied to the tip of the piston 11. The center of gravity of the piston 11 is located on the opening end side of the cylinder hole 10.

Further, the structure for adjusting the position of the center of gravity of the cylinder body 4 also has the additional mass 4 shown in FIGS. 4 (a) and 4 (b).
It is not limited to E, but may be adjusted by the additional mass 4F added to the inside of the opening 4G as shown in FIG. 8, or may be adjusted by both the additional masses 4E and 4F. You may do it. If the additional mass 4F is added to the opening 4G, the additional mass 4E for increasing the thickness of the cylinder body 4 to the outside becomes unnecessary, or the additional mass 4E can be made small. 4 is advantageous for downsizing.

In the above embodiment, the fitting holes 6A and 6B are provided on the torque member 3 side, and the slide pins 5A and 5B are provided on the cylinder body 4 side. With the above configuration, on the torque member 3 side,
Slide pin 5A with the tip facing inward in the vehicle width direction,
5B is provided, fitting holes 6A, 6B are provided on the cylinder body 4 side with the opening side facing outward in the vehicle width direction, and these slide pins 5A, 5B and fitting holes 6A, 6B are fitted. Movement of the cylinder body 4 with respect to the torque member 3 is possible in the same manner as in the above embodiment. In the case of such a positional relationship, the vertical line passing through the tip of the slide pin 5A becomes the first vertical line.

[0065]

As described above, according to the first or eighth aspect of the present invention, the vertical line passing through the tip of the sliding portion of the slide pin serving as the main pin is fitted with the vertical pin. Assuming a vertical line passing through the open end of the dowel, and setting the center of gravity of the piston and the center of gravity of the cylinder body projected on a plane containing these two vertical lines,
The moment that tilts the cylinder body with the piston accommodated is always kept small, the possibility of tilting the cylinder body is reduced, and a smooth braking feeling is obtained.

In particular, according to the invention as claimed in claim 2 or claim 9, the cylinder body in which the piston is accommodated does not tilt during the period from the unworn state of the brake pad to the maximum worn state. The effect is that a smooth braking feeling is surely obtained. Further, according to the invention of claim 3, since the cylinder body is not significantly increased in weight or increased in size, unsprung vibration is not deteriorated due to a large increase in unsprung weight of the vehicle. It is also very advantageous in disposing the disc brake device in the space inside the wheel with a small space.

According to the invention of claim 4, it is further advantageous for downsizing of the cylinder body. According to the invention of claim 5, the position of the center of gravity of the piston is closer to the opening end side, so that the position of the center of gravity of the piston is set to a predetermined position as in the inventions of claims 1, 2, 8 and 9. The effect is that it can be easily performed.

In the invention according to claim 6, the position of the center of gravity can be set more easily, and the amount of oil or the like supplied to and discharged from the pressure chamber for adjusting the fluid pressure is reduced. Therefore, it becomes advantageous in cost. Further, according to the invention of claim 7, a moment in a direction opposite to the moment of trying to wind the brake pad in the normal direction of the disc rotor is generated, so that partial wear of the brake pad is accelerated. There is an effect that it can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of a first embodiment of the present invention.

FIG. 2 is a partially cutaway front view of the disc brake device.

FIG. 3 is an explanatory diagram of setting and movement of barycentric positions of a piston and a cylinder body.

FIG. 4 is an explanatory diagram of a structure for adjusting the position of the center of gravity of a cylinder body.

FIG. 5 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 6 is a diagram for explaining the operation of the second embodiment.

FIG. 7 is a sectional view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 8 is an explanatory view of another structure for adjusting the position of the center of gravity of the cylinder body.

FIG. 9 is a diagram illustrating a problem of a conventional disc brake device.

[Explanation of symbols]

1 Disc Brake Device 2 Disc Rotor 3 Torque Member 4 Cylinder Body 4A, 4B Arm 4C Base 4D Claw 4E, 4F Additional Mass (Cylinder Body Center of Gravity Adjustment Means) 4G Opening 5A, 5B Slide Pin 6A, 6B Fitting Hole 7 , 8 brake pad 10 cylinder hole 10A seal ring 11 piston 11B tip part (piston center of gravity adjusting means) 12 hydraulic chamber (pressure chamber) 12A oil passage (fluid pressure supply / discharge means) 12B pipe (fluid pressure supply / discharge means) 15 mass body (Piston center of gravity adjustment means) L ₁ vertical line (first vertical line) L ₂ vertical line

Claims (9)

[Claims] 1. A pair of brake pads that are arranged so as to face each other so as to sandwich a disk rotor that rotates with a wheel from both sides, and a torque that is fixed to the vehicle body side and that supports the pair of brake pads so as to be capable of advancing and retracting in the disk rotor axial direction. A pair of slide pins having a member, a cylinder hole that faces the back side of the one brake pad, and a claw portion that faces the back side of the other brake pad, and a pair of slide pins into which the slide pins are slidably fitted; A cylinder body supported by the torque member so as to be capable of advancing and retreating in the axial direction of the disc rotor through a fitting hole, a piston accommodated so as to be capable of advancing and retracting in the cylinder hole, and interposed between the cylinder hole and the peripheral surface of the piston. Fluid pressure to and from the pressure chamber defined by the seal ring, the cylinder hole, the piston, and the seal ring. In a disc brake device including a fluid pressure supply / discharge means, a maximum position of a sliding area of the slide pin and the fitting hole is set as an initial position when the vehicle body is mounted, and the slide pin and the fitting are mounted when the vehicle body is mounted. The final position is the position where the sliding area of the hole is the minimum position, and the clearance between the peripheral surface of one of the pair of slide pins and the fitting hole, which is vertically upward when the vehicle body is mounted, and the peripheral surface of the fitting hole, A vertical line that is smaller than the clearance between the other slide pin and the peripheral surface of the fitting hole and that passes through the tip of the sliding portion of the one slide pin, and a vertical line that passes through the open end of the one fitting hole. And providing a cylinder body center of gravity adjusting means for adjusting the center of gravity position of the cylinder body and a piston center of gravity adjusting means for adjusting the center of gravity position of the piston. The center of gravity of the piston projected onto a plane including the two vertical lines is located outside the region sandwiched by the two vertical lines at the initial position and inside the region at the final position. And the center of gravity of the cylinder body projected on the plane is located between the first vertical line of the two vertical lines which is close to the center of gravity of the piston at the initial position. The disc brake device is characterized in that at the final position, the piston is positioned on the opposite side to the position of the center of gravity of the piston. 2. The magnitude of the moment determined by the mass of the piston and the distance between the center of gravity of the piston and the first vertical line at the final position is determined by the mass of the cylinder body and the final position. By the cylinder body center of gravity adjusting means and the piston center of gravity adjusting means, the cylinder body center of gravity of the cylinder body at the final position is adjusted so that the moment is determined by the center of gravity of the cylinder body and the distance between the first vertical lines. 2. The disc brake device according to claim 1, wherein the distance between the center of gravity of the piston and the first vertical line and the distance between the center of gravity of the piston and the first vertical line are adjusted. 3. The disc brake device according to claim 1, wherein the cylinder body center of gravity adjusting means is an additional mass added to the claw portion side of the cylinder body. 4. The disc brake device according to claim 1, wherein the cylinder body center of gravity adjusting means is an additional mass added to an opening for heat dissipation formed in the cylinder body. 5. A cross-sectional shape passing through the axial center of the piston is U-shaped, and the piston center-of-gravity adjusting means has a structure in which the open side of the U-shaped piston is directed to the bottom surface side of the cylinder hole. The disc brake device according to any one of claims 1 to 4. 6. The disc brake device according to claim 5, wherein an inner peripheral surface of the piston has a tapered shape in which a bottom surface side of the cylinder hole expands in diameter. 7. The disc brake device according to claim 1, wherein a portion of a surface of the piston that comes into contact with the brake pad is notched at a disc rotor forward rotation direction inflow side end portion. 8. A pair of brake pads that are arranged so as to face each other so as to sandwich a disk rotor that rotates with a wheel from both sides, and a torque that is fixed to the vehicle body side and that supports the pair of brake pads so as to be capable of advancing and retracting in the disk rotor axial direction. A pair of slide pins having a member, a cylinder hole that faces the back side of the one brake pad, and a claw portion that faces the back side of the other brake pad, and a pair of slide pins into which the slide pins are slidably fitted; A cylinder body supported by the torque member so as to be capable of advancing and retreating in the axial direction of the disc rotor through a fitting hole, a piston accommodated so as to be capable of advancing and retracting in the cylinder hole, and interposed between the cylinder hole and the peripheral surface of the piston. Fluid pressure to and from the pressure chamber defined by the seal ring, the cylinder hole, the piston, and the seal ring. Fluid pressure supply / discharge means, wherein one of the pair of slide pins and the fitting hole, which is vertically upward when the vehicle body is mounted, and the clearance between the peripheral surfaces of the fitting hole is the other slide pin. In the method of setting the center of gravity of the disc brake device, which is smaller than the clearance between the peripheral surfaces of the fitting holes, the maximum position of the sliding area of the slide pin and the fitting holes in the vehicle body mounted state is the initial position, The final position is the position where the sliding area of the slide pin and the fitting hole is the minimum when the vehicle is mounted, and the vertical line passing through the tip of the sliding portion of the one slide pin and the opening end of the one fitting hole. While assuming a vertical line passing through, the barycentric position of the piston projected on a plane including the two vertical lines is outside the region sandwiched by the two vertical lines at the initial position. And, in the final position, the center of gravity of the piston is set so as to be inside the region, and the center of gravity of the cylinder body projected on the plane is the initial position of the two vertical lines. First near the center of gravity of the piston
A center-of-gravity position setting method for a disc brake device, wherein the center-of-gravity position of the cylinder body is set so as to be opposite to the center-of-gravity position of the piston at the initial position and the final position with a vertical line interposed therebetween. . 9. The magnitude of the moment determined by the mass of the piston and the distance between the center of gravity of the piston and the first vertical line at the final position is determined by the mass of the cylinder body and the cylinder at the final position. The distance of the center of gravity of the cylinder body from the first vertical line and the center of gravity of the piston at the final position are equal to or greater than the magnitude of the moment determined by the center of gravity of the body and the distance between the first vertical lines. The method for setting the center of gravity of a disc brake device according to claim 8, wherein the distance from the first vertical line is set.