JPH0354984Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an automatic clearance adjustment device equipped with an overadjustment prevention mechanism with a parking brake.

BACKGROUND TECHNOLOGY This type of automatic clearance adjustment device with an over-adjustment prevention mechanism is disclosed in Japanese Patent Publication No. 57-61937, in which a cup-shaped piston is inserted into the hydraulic pressure chamber of the cylinder of the brake body, and the bottom of the piston is An adjuster constructed by screwing together a member with a male thread and a member with a female thread is mounted between the side wall at the rear of the cylinder, and the adjuster and the parking piston (corresponding to the free piston) are separated. If the hydraulic pressure in the hydraulic pressure chamber is below a predetermined value, the adjuster will adjust according to the displacement of the piston, but if the hydraulic pressure exceeds the predetermined value, the piston will be displaced unnecessarily due to deformation of the brake components. However, the adjuster prevents over-adjustment. In addition, an automatic clearance adjustment device for a disc brake with a parking brake mechanism disclosed in Japanese Utility Model Application Publication No. 161441/1980 consists of an adjuster screwed together with an adjustment nut and an adjustment bolt, which is fitted into a cylinder. The head of the adjustment bolt is brought into contact with the bottom of the cup-shaped piston, and a pushing member consisting of a small piston is inserted into a through hole provided in the center top surface of the head of the piston, thereby forming a thrust bearing for the adjustment bolt. .

Problems to be Solved by the Invention Incidentally, in the former prior art described above, the adjuster and the parking piston are separated, but there is a female thread forming the adjuster at the front end of the member to prevent over-adjustment. Since a small diameter piston mechanism is not provided, and the diameter of the fitting part of the member with the female thread with the piston is not small, the amount of liquid lost when operating this device is not small. Since the member is provided with a hermetic seal and the female threaded member rotates when the adjuster is operated, it is not very durable. Next, in the latter case, the top surface of the center of the head of the adjustment bolt, which is an adjuster component, comes into contact with a small piston inserted into a through hole provided in the piston, and the adjustment bolt is pressed by the small piston. However, the small piston is a thrust bearing for the adjustment bolt, and since the small piston is not always urged by a spring to press the adjustment bolt, it does not have an over-adjustment prevention function. I wasn't prepared.

Means for Solving the Problems The present invention has been made to solve the above problems, and in an automatic clearance adjustment device for hydraulic brake operation, a cup is installed in the brake operation cylinder 4 provided in the brake body 1. A type piston 6 is slidably provided, the piston 6 and the brake body 1 behind the cylinder 4 constitute a hydraulic chamber 11, and the piston 6 and the brake body 1 behind the cylinder 4
An adjuster consisting of two members threaded together is suspended between the cylinder 4, and the adjuster is made up of a rotatable first member and a second member which is non-rotatable but movable in the axial direction of the cylinder 4. The first member is pressed by the spring 15 so as to frictionally engage the piston 6, and the second member is a spring 36 with a spring force smaller than the spring force of the spring 15 on the side of the brake body 1 behind the cylinder 4. forming a cylinder in the recess of the piston 6 at the front of the first member, and slidably fitting an overtravel piston 18 into the cylinder, facing the first member of the piston 18; The side end face is biased by an overtravel spring 25 to contact the first member, and when the pressure of the fluid introduced into the hydraulic pressure chamber 11 exceeds a predetermined value, the overtravel piston 18 The automatic gap adjustment device is equipped with an over-adjustment prevention mechanism characterized in that the over-adjustment is pushed away from the first member against the spring force of the over-travel spring 25.

Operation When pressure fluid is introduced into the hydraulic chamber 11 from the pressure fluid inlet 9 of the brake body 1, the piston 6 moves to the left in the figure, and the adjuster also adjusts its length within the range of the back gap in the screw connection. increases and follows the movement of the piston 6. When the brake pads 7 and 8 are worn, the adjuster steering screw 12 rotates with respect to the adjuster staying nut 13, the length of the adjuster increases, the gap caused by the wear is eliminated, and the piston 6 is automatically adjusted. Follow the movement of. By the way, when a high hydraulic pressure equal to or higher than a predetermined value is introduced into the hydraulic pressure chamber 11 and the brake component is bent, and an excessive gap is created due to the deflection of the brake component, the overtravel piston 18 is removed from the adjusting screw. The overtravel piston 1 resists the spring force of the overtravel spring 25 pressing against the overtravel piston 12.
8 is separated from the adjusting screw 12, and the adjusting screw 12 is engaged with the bottom of the piston 6.
2 is prevented from rotating relative to the adjusting nut 13, thereby preventing over-adjustment.

Examples Examples of the present invention will be described below. The brake body 1 is slidably attached to a fixed part of the vehicle such as a wheel attachment part, and is attached to one side of a disc rotor 5 supported by a wheel hub or the like rotatably attached to the wheel attachment part. ing.
The brake body 1 includes a bridge-shaped member 2 extending beyond the periphery of the disc rotor 5, and the brake operation cylinder 4 is a part of the brake body 1 and is provided on one side of the disc rotor 5. . The cylinder 4 has an opening at the end facing the disk rotor 5, and a cup-shaped piston 6 is slidably disposed within the cylinder 4, the cylinder having a closed end at the open end of the cylinder. A brake pad 7 is carried by a support (not shown) between the front face of the piston 6 and the side surface of the disc rotor 5, and another brake pad 8 is carried by a support (not shown) at the front end of the bridge member 2 to support the disc rotor 5. It is carried on the opposite side of 5. The cylinder 4 has a pressure fluid inlet 9 through which fluid from the master cylinder or the like enters the cylinder and presses the cup-shaped piston 6 away from the brake body at the rear of the cylinder 4, i.e. from the closed end wall 3; The brake pad 7 is pressed against the disc rotor 5 and the pressure fluid acts on the closed end wall 3 and presses the other brake pad 8 against the disc rotor 5 via the bridge 2. A hydraulic chamber 11 defined by the stepped hole 10 of the piston 6 fitted into the cylinder 4 and the closed end wall 3 is provided with a two-piece adjuster. This adjuster includes a first member having a male thread, that is, an adjusting screw 12, and a second member having a female thread.
That is, it consists of an adjusting nut 13, and these two members are screwed together with a necessary back clearance corresponding to the return amount of the piston 5. Note that, on the contrary, the first member may be provided with a female thread, and the second member may be provided with a male thread, and both members may be screwed together. The adjusting screw 12 fitted into the stepped hole 10 of the piston 6 has a flange 12.
a, and supported by a circlip 14 attached to the inner cylindrical wall near the open end of the piston 6, a set spring 15, via a thrust bearing 16, connects the flange 12a to the step 1 of the stepped hole of the piston 6.
It is provided so as to be pressed against 0a. Note that this step 10a and the flange 1 that abuts the step 10a
The front end outer circumferential surfaces of 2a are both tapered to ensure frictional engagement with both 10 and 12. Further, since a thrust bearing 16 is interposed between the spring 15 and the flange 12a, the adjusting screw 12 is rotatable. Further, a cylindrical body 19 constituting a cylinder of an overtravel piston 18 is fitted into the recess 17 at the front end of the stepped hole 10, and the piston 18 is tightly fitted into the cylindrical body 19 via a seal ring 20. Ru. The piston 18 is provided with a flange 21 and the adjusting screw 12 is provided with a protruding portion 22 that comes into contact with it. It is pressed toward the adjusting screw 12 by an overtravel spring 25 supported by an annular spring bearing 24 engaged with the adjusting screw 23 . Note that the air hole 27 of the piston 6, which is communicated with the hole of the cylindrical body 19 into which the piston 18 is fitted, is an elastic sealing ring that seals the cup-shaped piston 6 against the cylinder 4. The adjusting nut 13 screwed into the adjusting screw 12 has its rear end partially in contact with the closed end wall 3 at the rear of the cylinder and is fitted into the rotation regulating member 28 . is prevented from rotating on the closed end wall 3 by a projection 28a. Therefore, the adjusting nut 13 is movable in its axial direction, but cannot be rotated. A parking piston 30 is tightly and slidably fitted into the hole 29 of the closed end wall 3 by a seal 31, and the adjusting nut 13 is fitted with the parking piston 30 so as to be movable to the left in the axial direction. has been done. A rotatable cylindrical cam 32 is fitted inside the hole 29, and a connecting rod 33 is located between the groove 32a of the cam 32 and the groove 30a at the rear end of the parking piston 30. It has been intervened. The adjusting nut 13 is connected to the rear closed end wall 3 of the cylinder 4 via a rotation regulating member 28 by a return spring 36 supported by a spring receiver 35 that is engaged with a circlip 34 attached to the inner surface of the rear portion of the cylinder 4. is under pressure. The cylindrical cam 32 rotates clockwise in response to mechanical force from a handbrake (not shown), and connects the connecting rod 33 and the first and second members 12, 1 of the adjuster.
3, the piston 6 is moved to the left in the figure, and the cylinder 4 is moved to the right in the figure by receiving the reaction force. Here, the spring force of the set spring 15 is F ₁ and the spring force of the return spring 36 is F 1 .
F ₂ , the spring force of the overtravel spring 25 is
F ₃ , and the spring force F ₃ of the overtravel spring 25 is reduced by the hydraulic pressure P applied to the overtravel piston 18 . That is, the effective pressure receiving area A
When a force P×A is applied to the piston 18, the force P×A acts to reduce the spring force _F3 , and as the hydraulic pressure P increases further, the piston 1
The force acting on 8 overcomes the spring force of the spring 25 and causes the piston 18 to move in the opposite direction. Spring force F ₁ of each spring 15, 25, 36,
The relationship between F ₃ and F ₂ is initially set as F ₂ +F ₃ >F ₁ >F ₂ .

Next, the operation of this embodiment will be explained. When pressure fluid from the master cylinder is introduced into the hydraulic chamber 11 through the inlet 9, the piston 6 moves to the left in the figure,
The adjuster also increases its length within the back gap of the threaded connection and follows the movement of the piston 6.
When the brake pads 7 and 8 are worn, the adjuster staying screw 12 rotates relative to the adjusting nut 13, increasing the length of the adjuster, eliminating the gap caused by the wear, and allowing the piston 6 to move. Follow the instructions and automatically adjust the gap. By the way, when the brake pads are operated in a worn state, the hydraulic pressure introduced into the hydraulic pressure chamber 11 is
If P ₁ is not so high, this hydraulic pressure P ₁ will move the cup-shaped piston 6 to the left in the figure, and the amount of movement at this time is larger than the back gap between the adjusting screw 12 and the adjusting nut 13, so it is set. The spring 15 is deflected, the frictional engagement between the adjusting screw 12 and the piston 6 is released, the adjusting mechanism is activated, the adjusting screw 12 rotates with respect to the adjusting nut 13, and the adjusting screw 12 is rotated. It comes into contact with the piston 6 and is frictionally engaged, eliminating the gap caused by wear of the pad and automatically adjusting the gap. (That is, in this case each spring 15, 25,
36 is in a state of F ₁ −F ₃ <F ₂ ), and furthermore, when a high hydraulic pressure P ₂ exceeding a predetermined value is introduced into the hydraulic pressure chamber 11, the overtravel piston 18 The spring force of the overtravel spring 25 that presses the adjusting screw 12
F ₂ decreases due to the force of P ₂ (the above hydraulic pressure) x A (effective cross-sectional area of the piston 18), and the overtravel piston 18 deflects the overtravel spring 25 and moves to the left in the figure, causing the piston to 18 protrusions 22 are pushed away from the adjusting screw 12,
That is, the spring force of the overtravel spring 25
Since F ₃ has no relation to the spring forces F ₁ and F ₂ of the other springs, the force related to both springs of the return spring 36 of the set spring 15 (F ₁ >F ₂ ) acts on the adjuster mechanism. Therefore, the frictional engagement between the cup-shaped piston 6 and the adjusting screw 12 is not released, and the adjusting screw 12 does not rotate relative to the adjusting nut 13, so the return spring 36 is deflected and the adjusting screw 12 is not rotated. is the parking piston 30 along with the adjusting nut 13.
However, the adjuster mechanism does not operate, and the adjustment mechanism does not operate to compensate for the excessive clearance caused by the deflection of the brake component when the hydraulic pressure P ₂ exceeds the predetermined value. Automatic adjustment device does not operate.

Effects of the Invention As described above, the present invention configures a cylinder in the recess 17 of the piston 6 at the front of the adjusting screw 12, and applies the spring force F ₃ of the overtravel spring 25 to the cylinder.
When the overtravel piston 18 pressed by the screw 2 is inserted and the hydraulic pressure P exceeds a predetermined value, the piston 18 is activated and separates from the screw 12 against the spring force _F3 of the spring 25, and the overtravel piston 18 is inserted. Prevents azimuth. Therefore, the amount of fluid lost during operation of the piston 18 that prevents over-adjustment is determined by the effective pressure-receiving area A of the piston 18, and in the present invention, since the piston 18 can be made smaller, the loss when preventing over-adjustment is reduced. The amount of liquid can be reduced,
Therefore, there is an effect that the loss stroke of the foot brake can be reduced. Furthermore, if the adjuster is provided with a seal for sealing off the pressure fluid, the seal will deteriorate due to the operation (movement) of the adjuster, but the adjuster of the present invention does not require a seal. That is, since the adjuster does not have a seal, it also has the effect of being highly durable.

[Brief explanation of drawings]

The drawing is a cross-sectional view of the disc brake body of the present invention. In the figure, 1 is the brake body, 3 is the closed end wall at the rear of the cylinder, 4 is the brake operation cylinder, 5 is the disc rotor, 6 is the cup-shaped piston, 9 is the pressure fluid inlet, 11 is the hydraulic pressure chamber, and 12 is the asia. Staying Skrill, 13 is Asia Staying Nut,
15 is a set spring, 17 is a recess, 18 is an overtravel piston, 19 is a cylindrical body, 25 is an overtravel spring, 28 is a rotation regulating member,
29 is a hole in the closed end wall, 30 is a parking piston, 32 is a cylindrical cam, 33 is a connecting rod, and 36 is a return spring.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an automatic clearance adjustment device for hydraulic brake operation, a cup-shaped piston 6 is slidably provided in a brake operation cylinder 4 provided in a brake body 1, and the piston 6 and A hydraulic chamber 11 is formed by the brake body 1 at the rear of the cylinder 4, and an adjuster consisting of two screw-fitted members is suspended between the piston 6 and the brake body 1 at the rear of the cylinder 4. It consists of a first member that is rotatable and a second member that is non-rotatable but movable in the axial direction of the cylinder 4, the first member being in frictional engagement with the piston 6 by a spring 15. The second member is pressed against the rear side of the brake body 1 of the cylinder 4 by a spring 36 with a spring force smaller than the spring force of the spring 15, and is pressed into the recess of the piston 6 at the front of the first member. An overtravel piston 18 is slidably fitted into the cylinder, and the end surface of the piston 18 facing the first member is brought into contact with the first member by an overtravel spring 25. When the pressure of the liquid introduced into the hydraulic pressure chamber 11 exceeds a predetermined value, the overtravel piston 18 is pushed away from the first member against the spring force of the overtravel spring 25. An automatic gap adjustment device equipped with an over-adjustment prevention mechanism. (2) The rear part of the second member is slidably fitted into the front part of the parking piston 30 which is fitted into the hole 29 provided in the closed end wall 3 at the rear of the cylinder 4, and the parking piston 30 is fitted into the front part of the parking piston 30. It is connected to a rotatable cam 32 at the back of the hole 29 via a connecting rod 33, and by rotating the cam 32, the second member is slid. Claim No. 1 for utility model registration, characterized in that the parking brake is configured to be able to be applied.
An automatic gap adjustment device equipped with an over-adjustment prevention mechanism as described in . (3) The end surface side of the overtravel piston 18 facing the first member is an enlarged head, and the head is provided with a first
An automatic gap adjustment device equipped with an over-adjustment prevention mechanism as claimed in claim 1 of the registered utility model, characterized in that a protruding portion is provided that comes into contact with a member of the invention. (4) Automatic clearance adjustment equipped with an over-adjustment prevention mechanism according to claim 1 of the registered utility model claim, characterized in that the head of the first member that contacts the bottom of the cup-shaped piston 6 is a flange. Device. (5) The overcoat according to claim 1 of the utility model registration claim characterized in that the cylinder of the recess of the piston 6 in the front part of the first member is constituted by a cylindrical body 19 fitted into the recess. Automatic gap adjustment device with anti-adjustment mechanism.