JPH07253128A - Disc brake device - Google Patents

Abstract

PURPOSE:To secure an accurate retracting rate without enlarging a chamfered portion. CONSTITUTION:In a disc brake device, a circular ring installing groove 15 having rectangular section is formed on an inner hole 14 of a cylinder 13 to which a piston 12 pressing a pad 11 is inserted. A chamfered portion 16 tapered to the pade side is forme on an opening edge on the pad side of the ring installing groove 15. A retraction ring 18 is assembled in the ring installing groove 15 for sealing a portion between the piston 12 and the cylinder 13 and returning the piston 12 for releasing pressure after braking. A circular recession 17 opened to a pad side end wall 15a of the ring installing groove 15 is formed on the cylinder 13. A deformation allowing ring 19 made of compressive material is installed in the circular recession 17 for allowing deforming entrance of the retraction ring 18 into the circular recession 17.

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 used as a braking device for vehicles such as automobiles.

[0002]

2. Description of the Related Art As one type of disc brake device,
18 and 19, that is, an annular ring mounting groove 5 having a substantially rectangular cross section is formed in the inner hole 4 of the cylinder 3 into which the piston 2 pushing the pad 1 is inserted,
A chamfered portion 6 inclined to the pad side is formed at the opening edge of the ring mounting groove 5 on the pad side, and a retraction ring 7 that seals between the piston 2 and the cylinder 3 and returns the piston 2 when depressurizing after braking is provided. Some are designed so that they can be assembled in the ring mounting groove 5, for example, the actual opening 6
It is shown as a conventional example in the 4-21826 gazette.

In such a disc brake device,
When the maximum return amount (retract amount) of the piston 2 obtained at the time of depressurization after braking is defined by the size of the chamfered portion 6 and the hydraulic pressure in the cylinder is low (the elastic deformation of the retraction ring 7 causes the chamfered portion 6). Hydraulic pressure P regulated by
(If less than 1), the difference between the interval Xp between the pad 1 and the cylinder 3 and the initial interval X1 that occur during braking as shown in FIGS. 19 and 20 (the amount of deflection of the pad 1 and the cylinder 3, that is, the caliper). Is always smaller than the retract amount (Xp-Xo) obtained by the elastic return of the retraction ring 7 by a predetermined amount α1, and a constant amount α1 is always formed between the pad 1 and the piston 2 during depressurization after braking.

However, when the hydraulic pressure in the cylinder becomes P1 or more, the amount of flexure of the pad 1 and the cylinder 3 sequentially increases as the hydraulic pressure rises, but the amount of retract by the retraction ring 7 is related to the chamfered portion 6. As a result, since the piston 2 and the retraction ring 7 are slipped, the gap formed between the pad 1 and the piston 2 at the time of depressurization after braking is sequentially increased as the hydraulic pressure increases. When the hydraulic pressure in the cylinder decreases to P2, it becomes zero, and when it becomes P2 or more, it elastically deforms so as to cause the retraction ring 7 to have a reverse action and presses the piston 2 against the pad 1 as shown in FIG. As a result, the pad 1 comes into contact with the disk rotor 8 (see FIG. 18) and so-called dragging occurs.

A disc brake device in which the amount of flexure of the pad 1 and the cylinder 3 sharply increases at an extremely low pressure as shown by the chain double-dashed line in FIG. 20 (a caliper with low rigidity is used and a soft pad is used. In such a disc brake device, the amount of bending becomes larger than the retract amount and the pad 1 is dragged when the pressure is low.

[0006]

The above-mentioned problem is caused by the problem shown in FIG.
2 and FIG. 23 (the solid line is the retract amount characteristic line in the case of FIG. 19, and the broken line is the retract amount characteristic line in the case of FIG. 22. The in-cylinder hydraulic pressure at the break point of the broken line is slightly lower than that of the solid line. Value), the size of the chamfered portion 6 is enlarged to increase the maximum value of the retract amount obtained by the elastic return of the retraction ring 7, so that the retraction ring 7 is reversed. Although the working hydraulic pressure can be set to P3 (P3> P2) and can be improved, when such means is adopted, when the hydraulic pressure in the cylinder is low, the pad 1 and An interval α2 between the pistons 2 is larger than a predetermined amount α1.
Will always be formed. The present invention has been made to address the above-mentioned problems, and an object thereof is to ensure an appropriate retract amount without increasing the chamfered portion.

[0007]

In order to achieve the above-mentioned object, an annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing a pad is inserted, and the ring mounting groove is formed. A chamfer that is inclined to the pad side is formed at the opening edge of the pad side of the groove, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove. In the disc brake device configured as described above, an annular recess opening toward the pad side end wall of the ring mounting groove is formed in the cylinder, and
A deformation permitting ring, which is made of a compressible material and permits the entry deformation of the retraction ring into the annular recess, is assembled in the annular recess (the invention of claim 1). In the disc brake device described above, an annular recess opening toward the pad-side end wall of the ring mounting groove is formed in the cylinder, and the retraction ring is axially formed near the bottom of the ring mounting groove. A holding means for sandwiching is provided (the invention of claim 2). In the disc brake device described above, a closed space having a predetermined shape is formed inside the retraction ring (the invention of claim 3). In the disc brake device described above,
A compressible member is provided on the pad-side end surface of the retraction ring (the invention of claim 4). In the disc brake device described above, the axial length of the retraction ring is made shorter than the axial length of the ring mounting groove by a predetermined amount, and an annular recess is formed in the pad side end wall of the ring mounting groove. A compressible member that is softer than the retraction ring is provided between the bottom of the annular recess and the pad-side end surface of the retraction ring (the invention of claim 5). Further, in the disc brake device according to the fifth aspect, a holding means for holding the compressive member at a predetermined position is provided at the bottom of the annular recess (the invention of the sixth aspect). In each of the above cases, it is desirable that the diameter of the cylinder inner hole on the pad side of the ring mounting groove is set larger than the diameter of the cylinder inner hole on the non-pad side (the invention of claim 7).

[0008]

According to the invention of claims 1 and 2, the retraction ring is formed in the annular recess formed in the cylinder in response to an increase in hydraulic pressure after the elastic deformation of the chamfer of the retraction ring is completed. Elastically deforms toward. At the time of such elastic deformation of the retraction ring, a part of the retraction ring slides on the piston at the engagement part on the chamfered part side of the piston to cause relative displacement with respect to the piston, but the engagement on the opposite side. In the part, the retract ring is largely elastically deformed without causing relative displacement with respect to the piston, so the retract amount by the retract ring continues to increase as the hydraulic pressure increases. Therefore, the amount of bending of the pad and the cylinder, which increases as the hydraulic pressure increases, becomes larger than the retract amount of the piston due to the retraction ring. It is possible to accurately reduce drag to the area. Further, in the invention of claim 1, since the deformation permitting ring can prevent the rubber grease applied to the ring mounting groove of the cylinder from entering the annular recess, the annular recess is filled with the incompressible rubber grease. As a result, it is possible to prevent the elastic deformation of the retraction ring into the annular recess from being hindered. Further, in the invention of claim 2, since the retraction ring is axially clamped by the holding means in the vicinity of the bottom of the ring mounting groove, the retraction ring after deformation and restoration due to elastic deformation in the annular recess is formed. Inclination can be prevented and an accurate retract amount can be obtained.

According to the third aspect of the present invention, the retraction ring elastically deforms toward the internal closed space in accordance with the increase in hydraulic pressure after the elastic deformation of the chamfered portion of the retraction ring is completed, and the retraction ring is subjected to such retraction. Due to the elastic deformation of the ring, the retract amount due to the retraction ring continues to increase in accordance with the increase of the hydraulic pressure, similarly to the above-mentioned inventions of claim 1 and drags to the use region where the hydraulic pressure becomes higher than the conventional one. It can be reduced accurately. Further, since the invention of claim 3 can be implemented only by changing the configuration of the retraction ring itself, it can be easily implemented by replacing the retraction ring with an existing disc brake device.

According to the invention of claim 4, in addition to the normal elastic deformation of the retraction ring in accordance with the hydraulic pressure in the cylinder during braking, the axial direction of the retraction ring due to the volume change (reduction) of the compressible member. Since movement is obtained, it is possible to obtain an appropriate retract amount by the retracting action by the retraction ring and the retracting action by the elastic return of the compressive member when releasing the pressure after braking, and drag it to the usage range where high hydraulic pressure is achieved. It can be reduced accurately.

According to the fifth and sixth aspects of the present invention, when the hydraulic pressure in the cylinder is low in the initial stage of braking, the compressible member is compressed into the annular recess via the retraction ring, and the retraction ring is substantially elastically deformed. Instead, it moves axially toward the pad side and comes into contact with the pad side end wall of the ring mounting groove.After that, the retraction ring faces the chamfered portion in the same way as described above in response to the increase in the hydraulic pressure in the cylinder. The effect of elastic deformation is obtained. Therefore, in the initial stage of braking, the piston movement amount before the retraction ring elastically deforms toward the chamfered portion (the movement amount in the axial direction until the retraction ring contacts the pad side end wall of the ring mounting groove) is stable, and Even when depressurizing when the braking pressure is extremely low, a retracting action due to elastic return of the compressible member is obtained, and drag can be prevented. Also,
When the braking pressure is high, the retracting action by the retraction ring and the retracting action by the elastic return of the compressible member can be obtained at the time of depressurizing after braking, so that an accurate retract amount can be obtained, and a high hydraulic pressure is used. It is possible to accurately reduce drag to the area. Further, according to the invention of claim 6, when the compressible member is installed in the annular recess, the compressive member can be held at a predetermined position by the holding means, so that the assembling failure of the compressible member does not occur. Retract performance is obtained.

In the invention of claim 7, since the diameter of the cylinder inner hole on the pad side of the ring mounting groove is set to be larger than the diameter of the cylinder inner hole on the non-pad side, it is formed between the piston and the cylinder on the pad side of the ring mounting groove. The chamfered portion can be enlarged and the rubber grease flowing into the chamfered portion can be accurately discharged through the gap, and the chamfered portion is filled with the incompressible rubber grease to the chamfered portion of the retraction ring. It is possible to prevent the elastic deformation of the. Further, since the diameter of the hole in the cylinder on the side opposite to the pad is small, the piston does not wobble in the cylinder.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In this first embodiment, a ring is attached to an inner hole 14 of a cylinder 13 in which a piston 12 for pushing a pad 11 toward a disk rotor (not shown) is inserted. The groove 15 is formed. The ring mounting groove 15 has a substantially rectangular cross section and is formed in an annular shape along the inner hole 14. The ring mounting groove opening edge of the end wall 15a on the pad side (the left side in the drawing) has an annular chamfered portion inclined toward the pad side. 16 is formed, and the bottom wall 15b has an annular recess (groove) 17 that opens toward the pad-side end wall 15a.
The retraction ring 18 is assembled in the ring mounting groove 15, and the deformation allowing ring 19 is assembled in the annular recess 17.

The chamfered portion 16 is the retraction ring 1
A predetermined amount of elastic deformation to the lower left of the left side of FIG. 8 is allowed, and its axial dimension in the inner hole side is smaller than the axial dimension in the inner hole side of the conventional chamfered portion. Annular recess 17
Accommodates the deformation permitting ring 19 to permit elastic deformation of the retraction ring 18 to the upper left in the drawing, and its axial width is set in consideration of the sealing property. The retraction ring 18 is made of ethylene propylene rubber like the conventional one, and the piston 1
It has a function of engaging the outer periphery of 2 and the bottom wall 15b of the ring mounting groove 15 to seal between the piston 12 and the cylinder 13, and elastically deforming during braking to return the piston 12 into the cylinder 13 during depressurization after braking. is doing. Deformation allowance ring 1
Reference numeral 9 is made of an elastic body having heat resistance and a large number of cavities inside or a compressible material such as sponge, and has a function of allowing the deformation of the retraction ring 18 into the annular recess 17. ing.

In the disc brake device of the first embodiment configured as described above, when the hydraulic pressure in the cylinder is low, as shown in FIG. Due to the sliding resistance with the piston 12, the chamfered portion 16 is elastically deformed and engages with the wall surface of the chamfered portion 16. Since the elastic deformation amount of the retraction ring 18 at this time is β1 and the bending amount of the pad 11 and the cylinder 13 is almost zero, the retraction ring 18 is in the initial state shown in FIG. The hydraulic pressure returns to the atmospheric pressure) and the piston 12
Is returned to β1. When the retraction ring 18 returns to the initial state shown in FIG. 1, the amount of bending of the pad 11 and the cylinder 13 also becomes zero, and the state returns to the initial state. Therefore, between the pad 11 and the piston 12, β1 (β1 <β1 < α
The interval 1) is formed (see FIG. 3).

When the hydraulic pressure in the cylinder rises, as shown in FIGS. 2 (B) and 2 (C), the retraction ring 18 forms an annular recess formed in the cylinder 13 in response to the increase in the hydraulic pressure in the cylinder. The deformation permitting ring 19 is elastically deformed while being compressed toward the place 17. During such elastic deformation of the retraction ring 18, a part of the retraction ring 18 slides on the piston 12 at the chamfered side engaging portion of the retraction ring 18 and the piston 12.
Although it causes relative displacement with respect to No. 2, the retraction ring 18 at the engagement portion on the opposite side does not move away from the piston 12 and undergoes large elastic deformation in sequence as the hydraulic pressure in the cylinder increases. The amount continues to increase as the hydraulic pressure in the cylinder increases.
When the hydraulic pressure in the cylinder rises to a predetermined pressure P, the inside of the annular recess 17 is elastically deformed, and the retraction ring 18 is elastically deformed.
And is filled with a deformation allowance ring 19 that is compressed and deformed,
The amount of retract does not increase.

Therefore, the hydraulic pressure (the drag start pressure) at which the amount of bending of the pad 11 and the cylinder 13 which increases in accordance with the increase of the hydraulic pressure in the cylinder becomes larger than the retract amount of the piston 12 by the retraction ring 18 is set to a high value. It is possible to set the idle stroke (piston movement amount until the piston presses the pad against the disc rotor in the initial stage of braking) to be smaller than before, while accurately dragging to the usage area where the hydraulic pressure is higher than before. Can be reduced to Further, in this embodiment, the annular recess 17 of rubber grease (which prevents the ring mounting groove 15 from rusting) is applied to the ring mounting groove 15 of the cylinder 13.
Since the deformation permitting ring 19 can prevent the inward entry, that is, the deformation permitting ring 19 acts as a rubber grease entry preventing member, the annular recess 17 is filled with incompressible rubber grease so that the retraction ring 18 can be prevented. It is possible to prevent the elastic deformation into the annular recess 17 from being hindered.

In the first embodiment shown in FIG. 1,
As shown in FIG. 1, an annular recess 17 that opens toward the pad-side end wall 15a (opens downward in FIG. 1) is formed at the pad-side end of the bottom wall 15b of the ring mounting groove 15, and this annular shape is formed. Although the present invention has been implemented by mounting the deformation allowance ring 19 in the recess 17, an annular recess that opens in the pad side end wall 15a of the ring mounting groove 15 (opens to the right in FIG. 1) is provided in the cylinder 13. It is also possible to embody the present invention by forming a deformation allowance ring in this annular recess.

FIG. 4 shows a second embodiment of the present invention.
In this second embodiment, the retraction ring 11
8 is a C type made of spring steel near the bottom of the ring mounting groove 115 (arranged along the bottom of the ring mounting groove 115)
The ring 121 holds the ring 121 in the axial direction. The other parts have substantially the same structure as the first embodiment shown in FIG. 1 except that the deformation allowing ring (19) is not attached to the annular recess 117, and therefore, like reference numerals are given. The description thereof will be omitted.

In the disc brake device of the second embodiment configured as described above, the retraction ring 11
8 is elastically deformable toward the annular recess 117,
The same effect as the first embodiment shown in FIG. 1 can be obtained except for the effect of the deformation allowance ring (19), and the retraction ring 118 is located near the bottom of the ring mounting groove 115. Since it is sandwiched in the axial direction by the C-shaped ring 121 made of spring steel, it is possible to prevent the inclination of the retraction ring 118 (see FIG. 5) after the deformation and restoration due to the elastic deformation into the annular recess 117.
An exact retract amount can be obtained.

In the second embodiment shown in FIG. 4,
The retraction ring 118 is configured to be axially sandwiched by the C-shaped ring 121 made of spring steel in the vicinity of the bottom of the ring mounting groove 115. However, as shown in FIG. It is also possible to implement the present invention by configuring the retraction ring 118 to be axially sandwiched near the bottom of the ring mounting groove 115 by 113a. Also, devise the shape of the retraction ring, that is, the axial length (thickness) of the portion of the retraction ring located at the bottom of the ring mounting groove.
May be larger than the width of the ring mounting groove so that the retraction ring is axially clamped near the bottom of the ring mounting groove.

FIG. 7 shows a third embodiment of the present invention,
In the third embodiment, the annular recess 1 of each of the above embodiments is used.
There is no one corresponding to 7, 117, and as an alternative to this, a closed space R having a circular cross section is formed inside the retraction ring 218. Others are the first shown in FIG.
Since the structure is substantially the same as that of the embodiment, the same reference numerals are given and the description thereof is omitted. In the third embodiment, the right side portion of the retraction ring 218 in the drawing is a closed space R in which the inside is closed according to the increase in the hydraulic pressure in the cylinder during braking.
The action of elastically deforming toward is obtained, and substantially the same action as in the first embodiment (as long as the closed space R continues to decrease, the retract amount by the retraction ring 218 increases in accordance with the increase in the cylinder hydraulic pressure). It is possible to accurately reduce the drag to a use area where the hydraulic pressure is higher than in the conventional case while setting the idle stroke to be smaller than in the conventional case as in the first embodiment. it can. In addition, since the third embodiment can be carried out by changing the construction of the retraction ring 218 itself and the other construction can be maintained as it is, the retraction ring can be replaced with the existing disc brake device. Therefore, it can be easily implemented.

In the third embodiment shown in FIG. 7,
Although the closed space R having a circular cross section is formed inside the retraction ring 218, the closed space R has a notch 218a on one side of the retraction ring 218 as shown in FIG. The cutout 218a may be provided after adhering the space to the inside and the cutout 218a may be adhered. Also, considering the sealability between the piston 212 and the cylinder 213 by the retraction ring 218, the cutout 218a is shown in FIG. 8B. Thus, the closed space R may be provided at a position biased to the pad side. Further, the cross-sectional shape of the closed space R is not limited to the above-mentioned circular shape, and may be an elliptical shape, a triangular shape, or a quadrangular shape as shown in (C), (D), and (E) of FIG. Good.

FIG. 9 shows a fourth embodiment of the present invention.
In the fourth embodiment, as in the third embodiment, there is no equivalent to the annular recesses 17, 117 of the first and second embodiments. Instead of this, the pad side of the retraction ring 318 is used. Retraction ring 3 on the end face
A ring-shaped compressible member 322 made of sponge that is softer and more heat-resistant than 18 is provided. Others have substantially the same configuration as that of the third embodiment shown in FIG. 7, and therefore, the same reference numerals are given and the description thereof is omitted. This 4th
In the embodiment, in accordance with the increase of the hydraulic pressure in the cylinder during braking, the retraction ring 318 causes the piston 3 to move as shown in (A), (B), (C) and (D) of FIG.
The piston 312 moves in the moving direction due to the sliding resistance with 12, and the retractable ring 318 moves so that the compressible member 322 moves to the retractable ring 31.
8 and the end wall of the cylinder 313 on the pad side elastically contracts and deforms. As described above, in the fourth embodiment, in addition to the normal elastic deformation of the retraction ring 318, the axial movement of the retraction ring 318 due to the volume change (decrease) of the compressible member 322 is obtained, so that braking is performed. During the subsequent depressurization, an appropriate retract amount can be obtained by the retract action by the retraction ring 318 and the retract action by the elastic return of the compressible member 322, and the drag can be appropriately reduced to the usage area where the hydraulic pressure is high. You can

In the fourth embodiment shown in FIG. 9,
Although the compressible member 322 is provided on the pad-side end surface of the retraction ring 318, the compressive member 322 is attached to both end surfaces of the retraction ring 318 as shown in FIG. It is also possible to do so, and when carrying out with such a configuration, the retraction ring 318 and the ring mounting groove 31 of the compressible member 322.
Assembling into the inside of 5 can be prevented and the desired effect can be obtained accurately.

FIG. 12 shows a fifth embodiment of the present invention. In this fifth embodiment, the axial length of the retraction ring 418 is made shorter than the axial length of the ring mounting groove 415 by a predetermined amount γ. Further, an annular recess 417 is formed in the pad side end wall 415a of the ring mounting groove 415, and there is heat resistance between the bottom portion 417a of the annular recess 417 and the pad side end surface of the retraction ring 418, which is higher than that of the retraction ring 418. A ring-shaped compressible member 422 made of soft sponge is provided. The compressible member 4
The compressible member 4
A clearance is provided for facilitating the assembly of 22. Others have substantially the same configuration as that of the third embodiment shown in FIG.
The description is omitted.

In the fifth embodiment, when the hydraulic pressure in the cylinder at the beginning of braking is low, the compressibility is increased via the retraction ring 418 as the piston 412 moves to the pad side as shown in FIG. The member 422 has an annular recess 41.
7, the retraction ring 418 is axially moved to the pad side without being substantially elastically deformed, and comes into contact with the pad side end wall 415a of the ring mounting groove 415, and then the hydraulic pressure in the cylinder rises. In accordance with the above, the retraction ring 418 is provided with the chamfered portion 41 as in the above-mentioned respective embodiments.
An action of elastically deforming toward 6 is obtained. Therefore,
The amount of piston movement before the retraction ring 418 elastically deforms toward the chamfered portion 416 in the initial stage of braking (the amount of axial movement until the retraction ring 418 contacts the pad side end wall 415a of the ring mounting groove 415).
Is stable, and the retracting action due to the elastic return of the compressible member 422 is obtained even during depressurization when the braking pressure is extremely low, and the amount of bending of the pad and the cylinder changes as shown by the phantom line in FIG. Even when it is applied to a disc brake device (a device that uses a caliper with low rigidity and uses a soft pad), the drag can be prevented. Further, when the braking pressure is high, the retracting action by the retraction ring 418 and the retracting action by the elastic return of the compressible member 422 can be obtained at the time of depressurizing after braking, and an appropriate retract amount can be obtained, and a high liquid amount can be obtained. It is possible to accurately reduce the drag to the use area that becomes the pressure.

In the fifth embodiment shown in FIG. 12, a compressible member 422 is provided between the flat bottom portion 417a of the annular recess 417 and the pad-side end surface of the retraction ring 418.
Is simply provided, but in FIG.
As shown in (B) and (C), the bottom portion 417a of the annular recess 417 and the end portion of the compressible member 422 that engages with the bottom portion 417a have a wedge shape or an arc shape in cross section, and the annular recess 417 is formed.
It is also possible to implement so that the compressible member 422 is accurately held at a predetermined position of the bottom portion 417a of the. In such a case, when the compressible member 422 is installed in the annular recess 417, the compressible member 422 can be accurately held at a predetermined position, so that the compressible member 422 is distorted, bent, or biased during assembly. Assembling failure does not occur, and the desired retract performance is obtained. As shown in FIG. 16A, a holding hole 417b is provided at the center of the bottom portion 417a of the annular recess 417 so that the compressible member 422 is properly held at a predetermined position of the bottom portion 417a of the annular recess 417. 16B, or as shown in FIG. 16B, the bulging portion 422a fitted to the bottom portion 417a of the annular recess 417 is formed at the end of the compressible member 422 on the annular recess side. The compressive member 4 is provided at a predetermined position of the bottom portion 417a of the annular recess 417.
It is also possible to implement so that 22 is held accurately.

FIG. 17 shows a sixth embodiment of the present invention. In the sixth embodiment, the cylinder inner hole diameter D1 on the pad side of the ring mounting groove 515 is set larger than the cylinder inner hole diameter D2 on the non-pad side. Has been done. Others have substantially the same configuration as that of the first embodiment shown in FIG. 1, and therefore, like reference numerals are given and the description thereof is omitted. In the sixth embodiment, in addition to the function and effect of the first embodiment of FIG. 1, a gap S formed between the piston 512 and the cylinder 513 on the pad side of the ring mounting groove 515.
Can be increased, and the rubber grease flowing into the chamfered portion 516 can be accurately discharged through the gap S. The chamfered portion 516 is filled with incompressible rubber grease and the chamfered portion of the retraction ring 518 can be 516
It is possible to prevent the elastic deformation to the hindrance from being hindered. Further, the cylinder inner hole diameter D2 on the side opposite to the pad is small (the piston 51
The clearance between the two is usually about 0.015mm)
Therefore, the piston 512 does not wobble in the cylinder 513. It should be noted that setting the diameter of the cylinder inner hole on the pad side of the ring mounting groove to be larger than the diameter of the cylinder inner hole on the non-pad side can be similarly performed in the second to fifth embodiments.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the first embodiment shown in FIG.

FIG. 3 is a diagram showing the relationship between the in-cylinder hydraulic pressure, the retract amount and the bending amount obtained in the first embodiment shown in FIG.

FIG. 4 is a cross-sectional view of essential parts showing a second embodiment of the present invention.

5 is a cross-sectional view of essential parts showing a problem in the case where there is no C-shaped ring in the second embodiment shown in FIG.

FIG. 6 is a cross-sectional view of essential parts showing a modified example of the second embodiment.

FIG. 7 is a cross-sectional view of essential parts showing a third embodiment of the present invention.

8 is a cross-sectional view showing a modified example of the retraction ring shown in FIG.

FIG. 9 is a sectional view of an essential part showing a fourth embodiment of the present invention.

FIG. 10 is an operation explanatory view of the third embodiment shown in FIG.

FIG. 11 is a cross-sectional view of essential parts showing a modification of the fourth embodiment.

FIG. 12 is a sectional view of an essential part showing a fifth embodiment of the present invention.

FIG. 13 is an operation explanatory view of the fifth embodiment shown in FIG.

FIG. 14 is a diagram showing the relationship between the in-cylinder hydraulic pressure, the retract amount, and the deflection amount obtained in the fifth embodiment shown in FIG.

FIG. 15 is a cross-sectional view of essential parts showing a modified example of the fifth embodiment.

FIG. 16 is a cross-sectional view of an essential part showing another modification of the fifth embodiment.

FIG. 17 is a cross-sectional view of essential parts showing a sixth embodiment of the present invention.

FIG. 18 is a sectional view showing an example of a conventional disc brake device.

FIG. 19 is an operation explanatory view of the conventional example shown in FIG. 18.

FIG. 20 is a diagram showing the relationship between the in-cylinder hydraulic pressure, the retract amount, and the deflection amount obtained in the conventional example shown in FIGS. 18 and 19.

FIG. 21 is an operation explanatory diagram when the hydraulic pressure in the cylinder becomes high in the conventional example shown in FIGS. 18 and 19.

FIG. 22 is an operation explanatory view of a conventional example in which a chamfered portion is enlarged.

FIG. 23 is a diagram showing the relationship between the in-cylinder hydraulic pressure, the retract amount, and the deflection amount obtained in the conventional example shown in FIG. 22.

[Explanation of symbols]

11 ... Pad, 12 ... Piston, 13 ... Cylinder, 14
... Inner hole, 15 ... Ring mounting groove, 15a ... Pad side end wall,
16 ... Chamfered portion, 17 ... Annular recess, 18 ... Retraction ring, 19 ... Deformation allowance ring, 118 ... Retraction ring, 121 ... C-shaped ring (holding means), 113
a ... Protrusion (holding means), 318, 418 ... Retraction ring, 322, 422 ... Compressible member, 417 ... Annular recess, R ... Closed space, D1 ... Pad side cylinder inner hole diameter,
D2 ... In-cylinder hole diameter on the non-pad side.

Claims (7)

[Claims] 1. An annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing the pad is inserted, and a pad side opening edge of the ring mounting groove is inclined toward the pad side. In the disc brake device, wherein a chamfered portion is formed, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove, An annular recess that opens toward the pad-side end wall of the groove is formed in the cylinder, and the deformation allowance that allows the retraction ring to enter the annular recess is made of a compressible material in the annular recess. Disc brake device with a ring attached. 2. An annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing the pad is inserted, and an opening edge of the ring mounting groove on the pad side is inclined toward the pad side. In the disc brake device, wherein a chamfered portion is formed, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove, An annular recess that opens toward the pad-side end wall of the groove is formed in the cylinder, and holding means for holding the retraction ring in the axial direction near the bottom of the ring mounting groove is provided. Disc brake device. 3. An annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing the pad is inserted, and a pad side opening edge of the ring mounting groove is inclined toward the pad side. In the disc brake device, a chamfered portion is formed, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove. A disc brake device, wherein a closed space having a predetermined shape is formed inside a ring. 4. An annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing the pad is inserted, and a pad side opening edge of the ring mounting groove is inclined toward the pad side. In the disc brake device, a chamfered portion is formed, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove. A disc brake device, wherein a compressible member is provided on an end surface of a ring on a pad side. 5. An annular ring mounting groove having a substantially rectangular cross section is formed in an inner hole of a cylinder into which a piston for pushing the pad is inserted, and a pad side opening edge of the ring mounting groove is inclined toward the pad side. In the disc brake device, a chamfered portion is formed, and a retraction ring that seals between the piston and the cylinder and returns the piston when depressurizing after braking is assembled in the ring mounting groove. The axial length of the ring is made shorter than the axial length of the ring mounting groove by a predetermined amount to form an annular recess in the pad side end wall of the ring mounting groove, and the bottom of the annular recess and the retraction ring are formed. A disc brake device characterized in that a compressible member softer than the retraction ring is provided between the pad-side end faces. 6. The disc brake device according to claim 5, wherein a holding means for holding the compressive member at a predetermined position is provided at the bottom of the annular recess. 7. The cylinder inner hole diameter on the pad side of the ring mounting groove is set to be larger than the cylinder inner hole diameter on the non-pad side.
Alternatively, the disc brake device according to item 6.