JPH022493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a disc brake, and more particularly, to a disc brake that improves the rust prevention effect of a disc rotor and improves its operating characteristics.

(Prior Art) Generally, when automobiles and other vehicles are exported overseas, they are often transported to the destination country by ship. In this case, the vehicles manufactured at the factory are first stored in a storage area near the shipping port, then loaded onto a transport vessel and sailed to the destination country, and then stored again in a storage area near the loading port in the destination country. , and then handed over to the user in the other country.

However, if such a vehicle uses disc brakes, the disc rotor of the disc brake is usually made of iron-based material, and the air in the storage area near the shipping port contains a large amount of salt. Although it is extremely rare, it may take several months due to the fact that the inside of the transport vessel is often hot and humid, and the total storage period at the shipping port and loading port, as well as the total voyage period to the destination country, is completely unpredictable. Due to these factors, the disc rotor may rust. Such conventional disc brakes are described in "Nitsun Laurel Service Bulletin" page 162 (1982).
No. 429, published by Nissan Motor Co., Ltd. in November). When rust occurs on the disc rotor, the degree of rust is different between the parts of the disc rotor that are close to the pads on the front and back sides and the other parts. When rust of varying degrees occurs on the disc rotor in this way, torque fluctuations occur in the braking torque when the disc brake is operated while the vehicle is running. This is called the "jadder" phenomenon, and is an undesirable phenomenon that impedes smooth braking sensation for the occupants. To prevent this type of rust from forming, it is necessary to form a phosphate film, which is used for rust prevention, on the surface of the disc rotor as a base for normal car body painting, or a compound layer mainly composed of Fe-Me-P. is possible.

On the other hand, semi-metallic friction materials have recently attracted attention as pads that can withstand high loads and extend their service life, and are beginning to be put into practical use. In particular, semi-metallic friction materials contain more thermally stable inorganic and metallic materials than organic asbestos, so they have good thermal stability and wear resistance that is 1/3 to 1/10 that of organic asbestos. It is very good. It has features such as low noise and good water fade.

(Object of the Invention) However, in a housing using such a semi-metallic friction material, the contact area with the disc rotor is small at the beginning of braking after off-line, and the above-mentioned compound layer is formed on the surface of the disc rotor. If this is the case, a problem arises in that the coefficient of friction, especially at the beginning of braking, decreases significantly, which may impede the control function.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems by forming a large number of grooves on the surface of the pad and forming a resin coating on the grooves.

(Structure of the Invention) The disc brake according to the present invention controls the wheel by engaging a disc rotor fixed to a wheel side member and made of iron-based material, and engaging with a vehicle body side member to clamp the disc rotor. A pair of pads are provided on the surface of the disc rotor.
Forming a compound layer mainly composed of Fe-Me-P system,
A semi-metallic friction material is used for the pad, and the pad is arranged in a direction substantially the same as the rotational trajectory of the disc rotor, so that powder of the compound that falls off from the surface of the disc rotor when the disc rotor is clamped is temporarily accumulated on the surface of the pad. The pad has a structure in which grooves are formed and a resin coating is formed on the surface of the pad on which the grooves are formed.

According to such a configuration or technical means,
Until the contact area of the semi-metallic pad with the disc rotor becomes larger and it becomes ``familiar''.
By slidingly contacting the resin coating layer, which has a coefficient of friction larger than that of semi-metallic, with the disc rotor, the coefficient of friction at the beginning of braking can be increased and a predetermined control function can be achieved.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 and FIG. 2 are diagrams showing an embodiment of the disc brake according to the present invention.

First, to explain the configuration, in Figure 1, 1
2 is a disc brake, and 2 is a disc rotor fixed to a wheel-side member (not shown), having its axis at the bottom in the diagram, and made of iron-based material. A pair of pads 3 are arranged near the sliding surfaces 2a on both the front and back sides of the disc rotor 2. One side of the pad 3 is fixed to an end on the side of the disc rotor 2 of a piston 7 that constitutes a hydraulic means 5 formed at one end of the caliper 4, and the other side of the pad 3 is fixed to the end of the piston 7 on the side of the disc rotor 2.
It is jointly supported by an arm 8 formed at the other end. The pad 3 is formed of a semi-metallic friction material (for example, HP-12 manufactured by Hitachi Chemical Co., Ltd.) containing steel fiber as a main component and other resins, friction fillers, etc. The caliper 4 is engaged with and supported by the vehicle body (not shown), and when the disc brake 1 is not in operation, the pair of pads 3 are separated from the sliding surface 2a of the disc rotor 2 at approximately equal intervals, and the disc brake 1 is in operation. At times, the pair of pads 3 are brought into contact with the sliding surface 2a with equal pressure so that the disk rotor 2 can be clamped. By pinching the disc rotor 2 with the pair of pads 3, the wheels can be braked, that is, the vehicle can be braked. Second
As shown in the figure, the surface of disk rotor 2 has
A compound layer mainly composed of Fe-Me-P is formed, and the interface with the disc rotor 2 has a thickness of t.
The iron phosphate compound layer has a thickness of 1.7μ or more, and a phosphate compound layer with a thickness (Tt) (T is 4 to 8μ) is formed on top of the iron phosphate compound layer. As a treatment method for forming such a Fe-Me-P-based compound layer on the surface of the disk rotor 2, the following methods can be considered as shown in the attached table.

First, "degreasing" is performed for 10 minutes at a temperature of 50 to 70 DEG C. in a strong alkaline cleaner containing sodium silicate as a main component and having a pH of 12 or higher (for example, "FC-4360" manufactured by Nihon Parkerizing Co., Ltd., concentration 20 g/). Next, after "washing" for 0.5 minutes at room temperature, the concentration is 10-20%.
"Pickling" is carried out for 0.5 minutes at room temperature in a HCl solution (containing 30 g of Fe). Next, wash with water for 0.5 minutes at room temperature.
After that, a surface conditioner containing colloidal titanium salt as the main component (for example, "Percolene Z" by Nippon Parkerizing Co., Ltd., concentration 3 g/, titanium concentration 50 ~
"Surface conditioning" for 0.5 minutes at room temperature in 100PPM)
I do. After that, a chemical conversion solution containing zinc and phosphoric acid as the main ingredients and a little bit of nickel as an etching agent (for example, "Parker 210" from Nippon Parkerizing Co., Ltd.) is applied.
"Film formation" is performed for 5 minutes at a temperature of 95 to 99 degrees Celsius in TA 13-14 Pt, Fe 3.5 g/containing), and a zinc phosphate compound layer containing iron zinc phosphate is formed on the surface of the disc rotor 2. is formed. After "film formation", after "rinsing" for 0.5 minutes at room temperature,
Furthermore, "hot water washing" is performed for 0.5 minutes at a temperature of 80℃.

In addition, as shown in Figures 3 and 4, pad 3
A groove 3b is formed on the sliding surface 3a that slides on the sliding surface 2a of the disc rotor 2, and when the pad 3 clamps the disc rotor 2, the groove 3b is formed with a groove 3b from the surface of the disc rotor 2. The fallen powder of the compound is temporarily accumulated. Since the trajectory of the groove 3b is formed in a substantially horizontal direction as shown in FIG. 3, the rotational direction of the disc rotor 2 and the trajectory direction of the groove 3b do not coincide with each other and are appropriately shifted from each other. . The surface roughness of the sliding surface 3a, that is, the depth of the grooves 3b is within a range of 20 to 40μ. Further, as shown in FIG. 4, a resin coating 6 is formed on the surface of the groove 3b formed on the sliding surface 3a. The component of this resin coating 6 is mainly epoxy-modified phenolic resin, and the amount applied is 3.5 to 12
mg/ ^cm2 .

Next, the effect will be explained. By forming a compound layer mainly composed of Fe--Me--P on the surface of the disc rotor 2, appearance rust (red rust) can be sufficiently prevented from occurring. Therefore, it is also possible to effectively prevent the aforementioned jitter phenomenon.

In addition, since a semi-metallic friction material is used as the material for the pad 3, the pad 3 has features such as withstanding high loads, good thermal stability, improved wear resistance, noise prevention, and good water fade. can have

In addition, when the disc rotor 2 is pressed against the sliding surface 3a of the pad 3, the sliding surface 3a of the disc rotor 2 is
A groove 3b is formed in which the powder of the compound that has fallen off from the groove 3b is temporarily accumulated, and the groove 3b
As shown in FIG. 3, the orbit is formed in a substantially horizontal direction and does not coincide with the rotational direction of the disc rotor 2, but is appropriately deviated from the rotation direction of the disc rotor 2. The powder can be easily discharged from 3b at any time. Therefore, the frictional coefficient μ can be increased without powder clogging the grooves 3b. Therefore, it is possible to prevent the frictional coefficient μ from decreasing significantly during the initial braking after going offline (approximately 50 times), and to quickly recover the frictional coefficient μ after the decrease.

Furthermore, since the resin coating 6 is formed on the surface of the grooves 3b formed on the sliding contact surface 3a, the semi-metallic pad 3 comes into sliding contact with the disc rotor 2 to some extent, increasing the contact area with the disc rotor 2. The resin coating layer, which has a coefficient of friction larger than that of semi-metallic, comes into sliding contact with the disc rotor 2 until it is "broken in", thereby increasing the frictional coefficient μ at the beginning of braking, thereby making it possible to exhibit a predetermined braking function. This point will be explained in detail below.

Figure 5 is a graph comparing the fluctuation state of the friction coefficient μ between an organic asbestos pad and a semi-metallic pad using an untreated rotor with no compound layer formed on its surface. As can be seen, the friction coefficient μ of asbestos pads is large and stable from the beginning of braking (solid line graph), but the friction coefficient μ of semi-metallic pads is initially low (dashed line graph). Ru. This is because the semi-metallic pad does not initially "familiarize" with the pad.Furthermore, when a rust-proof rotor with a compound layer formed on the surface of the disc rotor 2 is used, as shown in Fig. 6. As shown in the solid line graph, the frictional coefficient μ further decreases to 0.15 or less instead of 0.2, which significantly impairs the braking function. Therefore, when using a rust-proof rotor, if the surface roughness of the semi-metallic pad is increased (60 to 100μ), the friction coefficient μ can be reduced to 0.2 or less, as shown in the broken line graph in Figure 6. Only the decline can be prevented. However, the coefficient of friction μ at the beginning of braking remains low, and in practice it is difficult to increase the surface roughness of the semi-metallic pad as much as it would cause significant wear on the polishing tool (diamond chip). Moreover, the rust prevention ability of the rust prevention rotor will also be significantly degraded. Therefore, if a resin coating is formed on the somewhat rough surface of the semi-metallic, as shown in Figure 7, although the data is based on an untreated rotor, the semi-metallic pad on which the resin coating has been formed (solid line Graph) has a larger friction coefficient μ from the beginning of braking than the semi-metallic pad (graph with broken line) that does not have it.

In addition, the depth (surface roughness) of the grooves 3b formed on the sliding surface 3a of the semi-metallic pad 3 using a rust-proof rotor is set to 20 to 40μ, and the resin coating 6 is applied on the grooves 3b. If formed, the eighth
As shown in the figure, the friction coefficient μ temporarily decreases after braking starts, but it is still around 0.3 and does not affect the braking function at all. However, the depth of the groove 3b is set to 20~
When the resin coating 6 is not formed as 80μ, as shown in Fig. 9, the resistance decreases at the beginning of braking.
It ends up being around 0.2, and some even go below 0.15.

Next, when a resin coating 6 is formed on the sliding surface 3a of the semi-metallic pad 3 using a rust-proof rotor, the depth of the grooves 3b on the sliding surface 3a is set between 5 and 60μ. The graph obtained by changing the parameters is shown in FIG. 10. In the case of 60μ, the friction coefficient μ at the beginning of braking drops to 0.2.
In the case of 5μ, the friction coefficient μ at the beginning of braking does not decrease, but gradually decreases until it approaches 0.2, and subsequent recovery to the predetermined value (about 0.45 to 0.55 in this case) is significantly delayed. This means that the disc brake will not be able to regain its desired braking function by the time the vehicle is handed over to the user. When the depth of the groove 3b is 20 to 40 μ, the friction coefficient μ does not decrease at the beginning of braking, and even if it decreases a little later, it does not go below 0.3, and it recovers quickly to the specified value. . This is because the compound layer falls off from the surface of the anti-rust rotor 2, and the powder is released into the grooves 3b of the pads 3.
By temporarily accumulating within the resin coating 6, the coefficient of friction μ is slightly lowered.However, this powder is related to the depth of the grooves 3b and the direction of their trajectory, and when the resin coating 6 collapses and separates from time to time. Since both of them are discharged from within the grooves 3b, the friction coefficient μ does not decrease so greatly and recovers to its reference value quickly. The amount of resin coating 6 applied at this time is 3.5 to 12 mg/cm ² .

Furthermore, even if the resin coating 6 is formed on the sliding surface 3a of the pad 3, if the thickness of the resin coating 6 is small, it will easily peel off due to sliding with the disc rotor 2, and the resin coating 6 will be peeled off easily. Not only is it the same as without it, but the 11th
As shown in the solid line graph in the figure, the actual surface roughness may become smaller and the friction coefficient μ may even decrease slightly. Furthermore, if the thickness of the resin coating 6 is too large, the depth of the grooves 3b will be buried, and the resin coating 6 will be removed by sliding contact with the disc rotor 2 until it "fits in" with the base material of the pad 3. It takes time and as shown in Figure 12,
During this time, the frictional coefficient .mu. competes with the compound powder of the disc rotor 2, and the frictional coefficient .mu. decreases significantly and does not increase easily, requiring more than 100 braking cycles before it recovers to a predetermined value.

The above data measurement conditions are: inertial mass (front load) approximately 1400Kg, caliper model CL22V,
The vehicle speed was 50 km/hr, the deceleration was 0.3 g, the sliding surface temperature before braking was 100°C, and the asbestos pad for comparison was Nisshinbo's NP-01 (surface roughness 60μ).

From the above, the sliding surface 2a of the disc rotor 2
A compound layer mainly composed of Fe-Me-P is formed with a thickness of 4 to 8μ, and a depth of 20 to 20μ is formed on the sliding contact surface 3a of the pad 3.
As shown in FIG. 10, it has been found that the best results are obtained when a groove 3b of 40μ is formed and a resin coating 6 is formed at a coating amount of 3.5 to 12 mg/cm ² on the groove 3b. Ru.

It should be noted that there is no need to limit the treatment method to the above-mentioned method adopted in the present invention as long as it is possible to form a compound layer mainly composed of Fe--Me--P on the surface of the disc rotor.

Further, in the case of phosphoric acid-based treatment, it is not necessary to limit the treatment to zinc phosphate compounds as in the present invention, and compounds such as manganese phosphate, calcium phosphate, or other phosphoric acid-based compounds may be used.

Then, as a treatment method for forming the zinc phosphate compound layer, a rust preventive agent (for example, Nippon Parkerizing Co., Ltd.'s "P-
4555" may be applied diluted (about 10-30%). As a result, the friction coefficient μ decreases somewhat during the first 10 braking cycles, but does not change much, and on the other hand, it takes about twice as long to cause red rust than in the case without rust preventive agent.

(Effects of the Invention) As described above, according to the present invention, it is possible to prevent rust from forming on the disk rotor and the aforementioned jagging phenomenon occurring during the storage period of the vehicle and before the vehicle is delivered to the user. At the same time, while taking advantage of the features of the pads using semi-metallic friction material, it is possible to prevent the friction coefficient from significantly decreasing at the beginning of braking of the disc brake after going offline, thereby preventing the braking function from being impaired.

[Brief explanation of drawings]

1 is a cross-sectional side view of a disc brake according to the present invention, FIG. 2 is a partially enlarged sectional view of section A in FIG. 1, and FIG. 3 is a side view of the pad in FIG. 1.
4 is a partial cross-sectional view of FIG. 3, and FIG. 5 is a graph comparing the fluctuation state of the friction coefficient μ between an organic asbestos pad and a semi-metallic pad for an untreated rotor. Figure 6 shows the friction coefficient between a semi-metallic pad with a small surface roughness (20 to 40 μ) (solid line graph) and a semi-metallic pad with a high surface roughness (60 to 100 μ) (dashed line graph) against the anti-rust rotor. Figure 7 is a graph comparing the fluctuation state of μ, compared to an untreated rotor, a semi-metallic pad with a resin coating formed on its surface (solid line graph) and a semi-metallic pad without resin coating (broken line graph) Figure 8 is a graph comparing the fluctuation state of the friction coefficient μ with respect to the rust-proof rotor.
A graph showing the fluctuation state of the friction coefficient μ of a semi-metallic pad with a surface roughness of 20 to 40 μ and a resin coating on the surface. A graph showing the fluctuation state of the coefficient of friction μ of several semi-metallic pads without coating. Figure 10 shows a semi-metallic pad with a resin coating formed on its surface for a rust-preventing rotor, and its surface roughness. Figure 11 is a graph showing a comparison of fluctuations in the coefficient of friction μ for different types of pads. Figure 11 shows a semi-metallic pad with a small amount of resin coating on its surface (solid line graph) and a semi-metallic pad with no resin coating formed on the surface of the rust-preventing rotor. Friction coefficient μ with semi-metallic pad (dashed line graph)
Figure 12 is a graph showing a comparison of the fluctuation state of the rust-preventing rotor, with a semi-metallic pad with an excessive amount of resin coating formed on its surface (solid line graph) and a semi-metallic pad with no resin coating formed on its surface. 3 is a graph showing a comparison of the fluctuation state of the friction coefficient μ with respect to the graph shown in FIG. 1... Disc brake, 2... Disc rotor, 3... Pad, 3a... Sliding surface (surface), 3
b... Grooves, 6... Resin coating.

【table】

Claims (1)

[Claims] 1. A disc brake for a vehicle, comprising a disc rotor fixed to a wheel side member and formed of iron material, and a pair of pads that engage with a vehicle body side member and brake the wheel by clamping the disc rotor. A compound layer mainly composed of Fe-Me-P is formed on the surface of the disc rotor, and a semi-metallic friction material is used for the pad,
Grooves are formed on the surface of this pad in approximately the same direction as the rotational orbit of the disc rotor, in which the powder of the compound that falls off from the surface of the disc rotor when the disc rotor is clamped is temporarily accumulated. A disc brake for a vehicle, characterized in that a resin coating is formed on the surface of the formed pad.