JPS598027Y2 - Piston and cylinder sealing device in disc brakes - Google Patents

Description

[Detailed description of the invention] ・Technical field The present invention is provided between the cylinder and piston of a disc brake, and in addition to its original purpose of maintaining fluid tightness, it also has the function of retracting the piston during depressurization and reducing the brake operating gap. The present invention relates to improvements in sealing devices that perform automatic adjustment, etc., and particularly relates to techniques for preventing brake drag and pedal stroke fluctuations when brake fluid pressure is released due to elastic deformation of brake structural elements.

・Prior art Figures 1 and 2 show an example of a conventional disc brake.
Problems in conventional general sealing devices will be explained based on the drawings.

In FIG. 1, reference numeral 1 denotes a cylinder, which is integrally formed with a caliper 8 provided straddling a rotating disk 7.

A piston 5 is slidably fitted within the cylinder 1, and when brake fluid pressure is applied within the cylinder 1, the piston 5 moves forward to press the friction pad 6 against the disk 7.

A seal ring 2 is installed in a groove 9 provided in the circumferential direction on the inner peripheral surface 1a of the cylinder 1.

As shown in an enlarged view in FIG. 2, the seal ring 2 has a substantially rectangular cross-sectional shape, and the cross-section is surrounded by a front wall 9a, a bottom wall 9b, and a rear wall 9C as the groove wall surface on the forward movement side of the piston. It is installed in a groove 9 that is approximately rectangular in shape.

The seal ring 2 is installed with a certain interference in the depth direction of the groove 9, and the outer peripheral surface and the inner peripheral surface of the seal ring 2 are brought into close contact with the cylinder 1 and the piston 5, so that the cylinder 1 and the piston 5 are tightly connected. Braking fluid 4 supplied between
is sealed.

Chamfered portions 9d are provided on the front wall 9a and rear wall 9C of the groove 9, respectively.
and 9e are provided.

When brake fluid pressure is applied to the cylinder 1, the piston 5 presses the friction pad 6 against the disk 7, and at the same time elastic deformation occurs in the seal ring 2. When the brake fluid pressure is released, the elastic force (restoring force) that pulls back the piston 5 occurs. force) is generated.

When the friction pad 6 wears out and exceeds the amount of deformation of the seal ring 2, the inner peripheral surface 2a of the seal ring 2 and the piston 5
An amount of slippage corresponding to the amount of wear of the friction pad 6 occurs between them, and therefore, when the brake is released, the brake operation gap between the friction pad 6 and the disc 7 is always maintained by the amount of elastic deformation of the seal. Become.

The above is the principle of conventional sealing devices, but in reality it is difficult to realize a sealing device that operates ideally as described above, and problems such as brake dragging and brake pedal stroke fluctuations are likely to occur. Ta.

This dragging is undesirable because it causes loss of power, shortened life of the friction pad 6, and heating of the brake.

Furthermore, if the brake pedal stroke varies, the operating feel will vary, making it difficult to obtain a constant braking effect corresponding to a constant amount of brake operation.

First, I will explain the problem of drag.

Drag means that the friction pad 6 remains pressed against the disk 7 even after the brake fluid pressure is released, and the seal ring 2, which should act in the direction of pulling the piston 5 back, reverses itself after the brake fluid pressure is released. This is often caused by a condition that acts in the pushing direction.

That is, in the conventional sealing device, the seal ring 2
Since the elastic deformation of the seal ring 2 is regulated by the size of the chamfered portion 9d, the deformation of the seal ring 2 already fills the chamfered portion 9d even with a relatively low brake fluid pressure, thereby preventing further elastic deformation.

Therefore, when a higher braking fluid pressure is supplied and the piston 5 is pushed out with a large force, the caliper 8
is expanded by elastic deformation and the friction pad 6 is deformed in the compression direction, so that the amount of advance of the piston due to the elastic deformation (hereinafter referred to as brake deformation) of brake structural elements such as the caliper 8 and the friction pad 6 is The amount of advance of the piston 5 due to the elastic deformation of the seal ring 2 is exceeded.

At this time, the piston 5 is moved forward by sliding on the seal ring 2 that is prevented from elastic deformation, so after the brake fluid pressure is released, the piston 5 is only pulled back by the amount of elastic deformation by the seal ring 2. Therefore, the seal ring 2 is left in a position advanced by the amount of advance due to brake deformation from its original position, but as the piston 5 is pushed in as the elastic deformation of the brake control element is restored, the seal ring 2 is Due to the pushing, the ring 2 is elastically deformed in the opposite direction beyond its restored shape, and conversely, the elastic force (restoring force) of the seal ring 2 causes the piston 5 to be pushed out.

This is what is called brake drag.

In order to prevent dragging, it is sufficient to increase the elastic deformation ability of the seal ring 2.
In order to have a sufficiently large elastic deformation capacity, the chamfered portion 9
It is necessary to increase a.

However, the height and width W of the chamfered portion 9d are
It cannot be made too large in order to securely hold it while preventing it from falling over, and to increase its durability against shear deformation, that is, to ensure sufficient liquid-tightness over a long period of time.

Next, variations in brake pedal stroke will be explained.

As mentioned above, in the conventional sealing device, the seal ring already fills the chamfered portion 9d at a relatively low brake fluid pressure and cannot be deformed any further, whereas the brake deformation changes proportionally with the brake fluid pressure. This is the cause of brake operating gap variation, that is, brake drag.

When the brake operation gap changes, the amount of brake fluid to be supplied to the cylinder 1 during braking (hereinafter referred to as brake fluid amount) also changes, and the braking action is started by a slight advance of the piston 5 during the next braking. , the pedal stroke is varied.

Although the above-mentioned variation in pedal stroke is caused by variation in brake gap due to brake deformation, there is still another cause in the conventional sealing device.

That is, in order for the seal ring 2 to fulfill its original purpose of maintaining liquid tightness and at the same time pulling back the piston 5, the seal ring 2 must be installed in a state in which it is compressed by a considerable amount in the depth direction of the groove 9. However, if the seal ring 2 is compressed in the depth direction of the groove 9, the seal ring 2
will naturally extend in the width direction of the groove 9, so it is necessary to provide a gap X between the groove 9 and the seal ring 2 as shown in Fig. 2 to allow for this elongation during assembly. be.

Therefore, when the piston 5 swings due to severe vibrations caused by the vehicle running when the vehicle is not braking, the seal ring 2 moves back together with the piston 5 by a distance corresponding to the gap X in the width direction of the groove 9 ( (shakeback), and the amount of brake fluid fluctuates due to fluctuations in the gap X between the seal ring 2 and the rear wall 9C of the groove 9.

In other words, when the gap X is enlarged by the advance of the seal ring 2 during braking, a large amount of braking fluid is required due to the accompanying increase in volume.

In disc brakes, the diameter of the cylinder is larger than that of drum brakes, and as a result, the amount of braking fluid varies greatly with the movement of the seal ring 2. Therefore, this variation in the amount of braking fluid is due to the brake allowance dull stroke. has a major impact on

However, regarding this point, we have already seen Figures 2 and 3.
Solutions are known as shown in the figure.

In the one shown in FIG. 2, the bottom wall 9d of the groove 9 is inclined in the axial direction of the cylinder 1, so that the seal ring 2 always moves toward the deeper side of the groove 9 due to its own elastic force and becomes stable. In the case shown in FIG. 3, a backing plate 11 and a spring 12 are inserted between the rear wall 9C of the groove 9 and the seal ring 2, and the elastic force of the spring 12 causes the seal ring 2 to be constantly pushed through the backing plate 11. It is pressed toward the front wall 9a of the groove 9.

With the above two solutions, it is possible to prevent variations in the amount of brake fluid due to movement of the seal ring 2 in the width direction of the groove 9 within the groove 9. Fluctuations in fluid volume and resulting variations in pedal stroke cannot be prevented.

Purpose of the invention This invention was made for the purpose of alleviating the drawbacks of the conventional apparatus detailed above.

The purpose of this invention is to provide a sealing device that prevents disc drag and pedal stroke variations due to brake deformation.

In order to achieve this objective, the gist of the present invention is to create a disk that suppresses the rotation of the disk by pressing a friction pad against the rotating disk by a piston fitted in a cylinder. In a brake, a sealing device that maintains fluid tightness between the cylinder and the piston, allows the piston to move forward when the disc brake is activated, and causes the piston to retreat when the disc brake is not activated, the sealing device comprising: (1) the above-mentioned (2) an annular member made of an elastic material and having a substantially rectangular cross section, provided in the circumferential direction on the inner circumferential surface of the cylinder; (3) a seal ring that is installed in the groove in close contact with the cylinder and the piston and has a pressure receiving surface that receives the hydraulic pressure supplied to the cylinder; (3) a groove wall surface of the groove on the piston forward movement side; The brake fluid is installed in a preloaded state between the seal ring and the piston, and a high braking fluid pressure that is greater than the static friction force between the seal ring and the piston and that causes brake deformation is applied to the pressure receiving surface of the seal ring. an annular leaf spring member that applies a preload to the seal ring in a direction that causes it to move away from the groove wall surface, which is smaller than the forward force of the seal ring when applied, the seal as the piston moves forward; A space is formed that allows local elastic deformation of the piston side end of the ring, and the local elastic deformation exceeding a predetermined maximum deformation amount is prevented to create a space between the seal ring and the piston. a spring member having an inclined portion or a notch along an inner circumferential edge thereof;

Effects of the invention With this arrangement, the preload of the spring member is set to a value greater than the static friction force between the piston and the seal ring, so when the seal ring reaches its maximum deformation, the spring member is deformed. Even if there is no deformation, the seal ring and piston. Slippage is allowed to allow piston advancement to compensate for friction pad wear.

Therefore, when the brake hydraulic pressure is released, the piston is retracted solely according to the restoring force of the seal ring, and the brake operation interval is properly shaped.

On the other hand, when the friction pad is strongly pressed by the disc rotor and the hydraulic pressure acting on the pressure receiving surface of the seal ring becomes high enough to cause brake deformation, the preload of the spring member is greater than the forward force of the seal ring at this time. is set small, and the spring member starts to deform due to the force of the hydraulic pressure acting on the seal ring and the frictional force between the piston and the seal ring. Therefore, when brake deformation occurs, the seal ring will move against the piston. It is allowed to move with the piston without any slippage between the piston and the piston.

Therefore, when the brake fluid pressure is released, the spring member restores the piston to move the piston backward by the amount of movement caused by the brake deformation, and the seal ring restores the piston to move the piston back by the amount corresponding to the brake operation gap. Therefore, irrespective of the amount of brake deformation, the brake operation gap between the friction pad and the disc is properly shaped, eliminating brake drag and pedal stroke fluctuations.

Furthermore, even if the piston moves forward by a large amount due to brake deformation, the seal ring is only subjected to local elastic deformation of the maximum deformation amount, so the seal ring can be reliably prevented from falling over. At the same time, sufficient durability and liquid-tightness of the seal ring can be obtained.

Moreover, the spring member is installed in a preloaded state between the groove wall surface on the piston advancing side of the groove and the seal ring, and the seal ring is given a preload in the direction of separating it from the groove wall surface. , the seal ring is immovable in the groove width direction within the groove, and as the seal ring is moved by vibration etc., the position of the seal ring is moved and the pedal stroke changes accordingly. is also prevented.

Example FIG. 4 shows an embodiment of this invention.

The same parts as in the conventional device shown in FIG. 2 are given the same reference numerals and explanations are omitted, but the main difference between this embodiment and the conventional device shown in FIG. 2 is that the rubber etc. A wave spring 3 as a spring member is installed in a preloaded state between a seal ring 2 made of an elastic material and the front wall 9a of the groove 9 (groove wall surface on the forward side of the piston 5), and is separated from the front wall 9a. A directional preload is applied to the seal ring 2.

The value of this preload is larger than the static friction force between the seal ring 2 and the piston 5, and the braking fluid pressure supplied to the cylinder 1 causes elastic deformation (brake deformation) of the disc brake structural element. The pressure is set to a value smaller than the forward force of the seal ring 2, which receives the braking fluid pressure on its pressure receiving surface and receives the static friction force with the piston 5 when the brake fluid pressure is increased to the value that occurs.

Note that a chamfered portion 9e is provided on the rear wall 9C of the groove 9 into which the seal ring 2 is fitted, as shown in FIG. It has a shape.

The wave spring 3 has an annular shape as a whole as shown in FIG. 5, and a cut portion 3f is provided in a part thereof to form a C-shape.

The cutting portion 3f is provided for the purpose of facilitating installation of the wave spring 3 into the groove 9 and facilitating elastic deformation of the wave spring 3 during braking.

The wave spring 3 is called a wave spring because its cross-sectional shape has a wave-like shape as shown in FIG. The shape has a slight concave portion 3a, that is, the shape of a western bow.

The reason why the recess 3a is formed in the center of the cross-sectional shape of the wave spring 3 is to enable the seal ring 2 to be stably held by the two protrusions 3b, and to facilitate elastic deformation of the wave spring 3. This is for the purpose of

Furthermore, the reason why the wave spring 3 is shaped like a bow is that the inner peripheral edge of the wave spring has a leg portion 3d as an inclined portion, which allows the piston of the seal ring 2 to be inserted between the seal ring 2 and the wave spring 3. 5
At the same time, the wave spring 3 prevents elastic deformation of the seal ring 2 beyond a predetermined maximum amount of deformation, thereby forming a space 3e that allows local elastic deformation of the side end. This is to cause slippage between the two.

Note that the amount of elastic deformation of the wave spring 3 is determined by the amount of elastic deformation between the recess 3a and the front wall 9 of the groove 9.
It is determined by the distance S from a.

Here, the maximum amount of deformation is the amount of deformation where the end of the seal ring 2 on the piston 5 side is locally shear elastically deformed as the piston 5 moves forward, and is the amount of deformation between the piston 5 and the seal ring 2. A state of deformation in which friction (sliding) occurs in a positive manner.

This maximum amount of deformation is determined by the supporting position of the wave spring 3 with respect to the seal ring 2 and the material of the seal ring 2 (hardness, elastic modulus, etc.), and is equivalent to the gap in order to express the brake operation gap. is set to an appropriate value.

In this embodiment, the leg portion 3d of the wave spring 3 and the chamfered portion 9e provided on the rear wall 9C of the groove 9 serve as guides, so that the seal ring 2 can be easily installed, and the piston 5 can be attached to the cylinder. 1, the seal ring 2 is compressed in the depth direction of the groove 9, and as a result, the elongation of the seal ring 2 that occurs in the width direction can be absorbed by the elastic deformation of the wave spring 3. It is possible to install it without any play in the width direction of the groove 9.

This prevents the seal ring 2 from moving freely in the width direction of the groove 9, as in the known sealing device shown in FIG. Because of this, so-called shakeback, in which the piston 5 swings due to an excitation force applied to the brake from the outside and is pushed together with the seal ring 2 deeper than its proper position, does not occur.

Therefore, fluctuations in the pedal stroke due to movement of the seal ring 2 are suitably prevented.

However, the effects of the sealing device according to this invention are not limited to this.

The true value of this invention is demonstrated only during the operation described below.

6 and 7 show operating conditions of the sealing device shown in FIG. 4.

FIG. 6 shows the deformation of the sealing device during braking.

In the normal case where the brake fluid pressure is relatively low, almost no brake deformation occurs, so the piston 5 moves forward by a distance approximately equal to the brake gap, and the seal ring 2 is allowed in the space 3e by an amount corresponding to that distance. Shear elastic deformation occurs in a direction that narrows the space 3e.

Then, when the brake fluid pressure is released, the restoring force of the seal ring 2 reliably pulls back the piston 5 by the amount that it moved forward during braking, so that the brake operation gap is appropriately formed.

In the above state, the local elastic deformation of the piston 5 side end of the seal ring 2 is increased due to the friction of the friction pad 6, and the amount of elastic deformation is determined by the support position by the wave spring 3 and the property of the seal ring 2 (hardness When a predetermined maximum deformation amount (deformation limit) determined by the deformation coefficient and the elastic coefficient is reached, further local elastic deformation is prevented and slippage occurs between the seal ring 2 and the piston 5.

In this state, there is still a gap between the piston 5 side end (leg 3d) of the wave spring 3 that is in contact with the front wall 9a of the groove 9 and the seal ring 2, as shown in FIG. A space is left in which the seal ring 2 is allowed to move forward.

At this time, the preload of the wave spring 3 is the seal ring 2 and the piston 5.
Since the value is set to be larger than the static friction force between the wave spring 3 and the wave spring 3, the wave spring 3 is not deformed.

Therefore, the piston 5 moves forward relative to the seal ring 2, the amount of wear on the friction pad 6 is compensated for, and the friction pad 6 is pressed against the rotor 7.

When the brake fluid pressure is released, the piston 5 closes the seal ring 2
Since the maximum amount of deformation is restored, an appropriate brake operation gap is formed between the rotor 7 and the friction pad 6.

That is, the brake actuation gap is automatically adjusted to an appropriate value, and the maximum amount of deformation of the seal ring 2 is predetermined correspondingly so that an appropriate dimensional value of the brake actuation gap can be obtained.

Next, when a high brake fluid pressure is generated to cause brake deformation, the high brake fluid pressure is applied to the pressure receiving surface (rear end surface) of the seal ring 2, as shown in FIG.

For this reason, the seal ring 2 tends to move forward in a deformed state due to the acting force based on the braking fluid pressure and the frictional force with the piston 5, but the preload of the wave spring 3 is 2, the elastic deformation of the wave spring 3 is started against its preload.

In this case, the elastic deformation of the wave spring 3 increases proportionally as the brake fluid pressure increases, and the seal ring 2 slips between the moving piston 5 and the piston 5, which moves forward due to the brake deformation that also increases proportionally. It is allowed to move forward together with the piston 5 without being caused.

That is, the end portion of the seal ring 2 on the piston 5 side is moved in a direction to narrow the space left between the leg portion 3d of the wave spring 3 and the seal ring 2 while remaining in a deformed state.

Therefore, the relative advance of the piston 5 with respect to the cylinder 1 due to the brake deformation that increases proportionally with the increase in brake fluid pressure is absorbed by the elastic deformation of the wave spring 3, so that when the brake fluid pressure is released, the wave spring 3 The piston 5 is moved back by an amount of advance corresponding to the amount of deformation of the brake according to the restoring force of is forced to retreat.

That is, since the piston 5 is not moved forward relative to the contact surface with the seal ring 2 regardless of brake deformation, when the brake components are restored and the brake deformation becomes zero, the seal ring The piston 5 is pulled back by an amount of advance corresponding to the maximum deformation amount of 2, and the brake operation gap is appropriately formed.

As mentioned above, after the brake fluid pressure is released, the piston 5 is pulled back to a certain position in the axial direction with respect to the cylinder 1, regardless of the magnitude of the brake fluid pressure, and an appropriate brake operation gap is always ensured. The advantageous effect is that brake drag and pedal stroke fluctuations 1 are prevented all at once.

Furthermore, as mentioned above, since the pullback force of the piston 5, which conventionally relied only on the elastic deformation of the seal ring 2, is also generated by the wave spring 3, there is no need to force the seal ring 2 to deform excessively. 'No more (piston 5
This allows the maximum deformation of the side edges to be set small),
Therefore, the seal ring 2 can be made of a relatively hard material.

Therefore, compared to the conventional case where the piston is returned to its original position by the restoring force of the seal ring alone. In comparison, the advantage is that the seal ring 2 is reliably prevented from falling over and its durability and ability to maintain liquid tightness are improved.

Furthermore, since the seal ring 2 is held by the curved surface of the wave spring 3, and the wave spring 3 can also be elastically deformed,
Another advantage is that the seal ring 2 is less likely to be forced to undergo forced deformation locally, increasing the lifespan of the seal ring 2.

Moreover, since there is no need to make any changes to the conventional device except for the seal ring 2 and the groove 9, the drawbacks of the conventional device can be solved at a low cost, and there is an advantage that problems of weight and space do not occur.

Another embodiment is shown in FIG.

This embodiment is similar to the previous embodiment in that a leaf spring material is inserted in a preloaded state between the seal ring 2 and the front wall 9a of the groove 9, and the preload is applied to the seal ring 2.

The main differences from the previous embodiments are the cross-sectional shape of the leaf spring material and the chamfered portion 9d provided on the front wall 9a of the groove 9.

The spring 13 as a spring member is similar to the wave spring 3 of the previous embodiment in that it has an overall C-shape with a cut portion provided in a part of the ring, and as shown in FIG. A curved part 13 having a flange part 13a on the outer peripheral part thereof and serving as an inclined part bent along the inner peripheral edge to the same side as the flange part.
It is manufactured to have a cross-sectional shape of b.

The flange portion 13a is in contact with the front wall 9a of the groove 9, and the spring 1
3 and the front wall 9a.

Also in this embodiment, since the curved portion 13b of the spring 13 and the chamfered portion 9e of the groove 9 serve as guides, the groove 9 of the seal tongue 2
It is easy to insert the seal ring 2 into the groove 9, and it is possible to eliminate the play between the seal ring 2 and the groove 9 in the width direction of the groove 9.

FIG. 9 and FIG. 10 show the operating status of this embodiment.

FIG. 9 shows a case where braking is performed using a relatively low brake fluid pressure where brake deformation is negligible.
The piston 5 is allowed to move forward by local elastic deformation of the side end, and after the brake fluid pressure is released, the piston 5 is pulled back by the restoring force of the seal ring 2.

At this time, when the piston 5 moves forward due to wear of the friction pad 6, etc., the seal tongue 2 comes into contact with the curved part 13b of the spring 13, and the deformation of the side end of the piston 5 reaches a predetermined maximum deformation amount. For the first time, a slip occurs between the seal ring 2 and the piston 5, and the piston 5 moves forward with respect to the seal ring 2, so that the amount of wear on the friction pad 6 is compensated for.

When high brake fluid pressure is supplied and the brake deforms, as shown in FIG. The deformation is started against the preload, and the seal ring 2 is allowed to move forward together with the piston 5 while the piston 5 side end is in a deformed state without slipping between the seal ring 2 and the piston 5. ,
The amount of advance of the piston 5 due to brake deformation is absorbed by the spring 13.

In this case, since the end of the seal ring 2 on the cylinder 1 side is prevented from moving by the flange 13a of the spring 13, the seal ring 2 does not move in parallel, but due to overall elastic deformation, the end on the piston 5 side moves toward the piston. Move with 5.

The above-mentioned progress includes such cases.

In this embodiment as well, the piston 5 corresponds to the brake operation gap.
The elastic coefficient of the seal ring 2 is adjusted so that the advance of the spring 3 is mainly dealt with by local elastic deformation of the seal ring 2, and the brake deformation that increases in proportion to the braking fluid pressure is mainly dealt with by the elastic deformation of the spring 3. , and the preload of the spring 13 and its elastic modulus are set.

Therefore, this embodiment also provides substantially the same effects as those of the previous embodiment.

Moreover, according to this embodiment, the maximum amount of deformation of the seal ring 2 is mainly determined by the amount of deformation received by the curved portion 13b of the spring 13, so when determining the material of the seal ring 2, the hardness, elastic modulus, etc. This has the advantage that tolerances can be made relatively large and material selection is easy.

Further, as shown in FIG. 11, by forming a notch along the inner peripheral edge of the spring 13, the spring 1, which is a spring member having only a flange portion 14a and no curved portion 13b, can be formed.
4 can also be used, and this also forms a space 14e that allows elastic deformation of the seal ring 2 as the piston 5 moves forward even without deformation of the spring 14.
The effect is almost the same as that of the above-described embodiment, in that the end of the seal ring 2 on the side of the piston 5 is prevented from being deformed by more than a predetermined maximum deformation amount, and slippage is caused between the seal ring 2 and the piston 5. is obtained.

That is, since the seal ring 2 is supported by the spring 14 in the forward movement direction of the piston 5, the piston 5 side end of the seal ring 2 moves to a predetermined constant amount as the piston 5 moves forward by the brake operation gap. It is locally elastically deformed until this point is reached.

The amount of local deformation of the seal ring 2 is determined according to the properties of the seal ring 2 (hardness, elastic modulus, etc.) and the supporting position of the spring 14 with respect to the seal ring 2.

When the seal ring 2 reaches the maximum amount of deformation, further deformation is prevented and the piston 5 and the seal ring 2
A slip occurs between the friction pad 6 and the wear of the friction pad 6.

Further, when the brake fluid pressure is increased, the spring 14 is elastically deformed by being pressed against the seal ring 2 which has received the frictional force with the piston 5 and the acting force of the brake fluid pressure, and the seal ring 2 is elastically deformed together with the piston 5. It is allowed to move forward.

According to this embodiment, since the shape of the spring 14 is relatively simple, there is an advantage that the spring 14 can be manufactured and installed easily.

Further, as shown in FIG. 14, a spring 16 having a waveform parallel to the radial direction of the ring can also be used, and the spring 16 described above can also be used.
It produces almost the same effect as 14 mag.

In this case as well, the spring 1 is similar to the spring 14 in FIG.
A cutout or the like is formed on the inner circumferential edge of the piston 5, and the inner circumferential edge and the piston 5
Of course, a certain space should be provided between the seal ring 2 and the outer peripheral edge of the seal ring 2 to allow elastic deformation of the seal ring 2 when the piston moves forward, and to prevent deformation exceeding the maximum deformation.

Generally, an annular leaf spring material tends to undergo large elastic deformation near the cut portion (3f in FIG. 5), and in particular, the one shown in FIGS. 8 and 11, for example,
As shown in the figure, there is a slight overlap part 13C near the cut part.
It is effective to make sure that this occurs.

In such a case, there is an advantage that variations in preload in the circumferential position of the annular spring 13 are improved.

Further, as shown in FIG. 13, a spring 1 as a spring member
It is also possible to shape the groove 9 by press-fitting the ring 15 after mounting the spring 13, thereby allowing the spring 13 to be mounted without providing a cut portion.

This has the advantage that variations in preload in the circumferential position of the spring 13 are completely eliminated.

[Brief explanation of the drawing]

Fig. 1 is a front cross-sectional view of a disc brake including a conventional sealing device, Fig. 2 is a central sectional view of a main part showing an example of a conventional sealing device, and Fig. 3 is a front sectional view of a disc brake including a conventional sealing device. FIG. FIG. 4 is a central sectional view of a main part showing an embodiment of the present invention, and FIG. 5 is a front view of a wave spring used in the device shown in FIG. 4. FIGS. 6 and 7 are explanatory diagrams showing the operating conditions of the apparatus shown in FIG. 4, respectively. FIG. 8 is a central sectional view of a main part showing another embodiment of the present invention, and FIGS. 9 and 10 are explanatory diagrams showing the operating state of the apparatus shown in FIG. 8, respectively. FIG. 11 is a central sectional view of a main part showing still another embodiment of the present invention, FIG. 12 is a front view of a main part of a spring used in still another embodiment, and FIG. 13 is a front view of a main part of a spring used in still another embodiment. 14 is a central sectional view of a main part showing an embodiment, and FIG. 14 is a front view of a spring 16 used in yet another embodiment. 1...Cylinder, 2...Seal ring, 3...Wave spring (spring member), 5...
Piston, 9...Groove, 9a...Front wall (
Piston forward side wall surface), 13, 14, 16...
・Spring (spring member), 3e, 13e, 14e・Curve・
Space, 3d...Leg (slanted part), 13b/curved/curved part.

Claims (1)

[Claims for Utility Model Registration] A disc brake that suppresses rotation of a rotating disc by pressing a friction pad with a piston fitted into a cylinder to maintain fluid tightness between the cylinder and the piston. The sealing device allows the piston to move forward when the disc brake is applied, and allows the piston to move backward when the disc brake is not applied, the sealing device having a substantially rectangular cross-sectional shape provided in the circumferential direction on the inner circumferential surface of the cylinder. a groove, and an annular member made of an elastic material having a substantially rectangular cross-sectional shape, which is installed in the groove so as to be in close contact with the cylinder and the piston on the outer circumferential surface and the inner circumferential surface, respectively, and is supplied to the cylinder. A seal ring having a pressure-receiving surface that receives the working hydraulic pressure applied thereto is installed in a preloaded state between the groove wall surface of the groove on the piston advancing side and the seal ring, and the static friction force between the seal ring and the piston is reduced. Separating from the groove wall surface a preload that is greater than the forward force of the seal ring when high braking fluid pressure that causes brake deformation is applied to the pressure receiving surface of the seal ring. An annular leaf spring material applied to the seal ring in the direction, which forms a space that allows local elastic deformation of the piston side end of the seal ring as the piston moves forward, and has a predetermined shape. a spring member having an inclined portion or a notch along the inner peripheral edge that prevents the local elastic deformation exceeding the maximum amount of deformation and causes slippage between the seal ring and the piston; A sealing device for the piston and cylinder in disc brakes.