JP2643955B2 - Anti-lock brake - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an anti-lock brake for a motorcycle or the like having a function of preventing a tire from being locked due to braking.

(Prior art) If the rotation of the wheel is locked by the brake during braking of the motorcycle, the tire is likely to slip or skid on the track, so braking is performed so that the rotation of the wheel is not completely locked during the brake operation. Brakes having an antilock mechanism for controlling torque are known (for example, Japanese Patent Application Laid-Open Nos. 60-25835 and 61-1).
No. 10658).

(Problems to be Solved by the Invention) These antilock mechanisms all control the hydraulic pressure supplied for braking, but many devices such as pumps, accumulators, and solenoid valves are interposed in the hydraulic supply path. In addition, since it is necessary to additionally provide a slip detecting mechanism, there is a problem in that it is complicated and expensive, and the space required for arrangement is large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an anti-lock brake for a motorcycle or the like that operates efficiently with a simple structure in order to solve the above problems of the conventional brake having an anti-lock mechanism.

(Means for Solving the Problems) According to the present invention, a brake caliper is mounted so as to be displaceable in accordance with a braking torque, a position detecting rod for detecting the displacement of the brake caliper is provided, and the brake caliper is braked to brake a brake disk. A pressure chamber is provided in the hydraulic oil passage from the master cylinder to the brake caliper to guide the hydraulic pressure on the brake caliper side, and this pressure chamber is expanded and contracted in conjunction with the displacement of the brake caliper. A position detecting rod that is displaced so that the pressure chamber is resiliently supported by the position detecting rod and that is displaced relative to the position detecting rod in response to the pressure of the pressure chamber. Is the brake according to a combined displacement obtained by combining the displacement of the position detecting rod and the displacement of the pressure responsive member. A check valve for controlling the opening and closing of a hydraulic oil passage leading to the caliper is provided, and a throttle resistor is provided between the pressure responsive member and the pressure chamber to hydraulically regulate the displacement speed of the pressure responsive member.

(Operation) In the present invention, when braking, the reaction force acts on the brake caliper against the braking torque applied to the brake disc by the brake caliper, and causes the displacement of the position detection rod via the link. The displacement of the position detection rod increases with the braking torque, but until the rotation of the tire is locked, a pressure response member (spool) that responds to the displacement of the position detection rod and the oil pressure in the pressure chamber (oil pressure on the brake caliper side). The combined displacement obtained by combining the displacement with the displacement increases to open the check valve (pressure regulator valve), so that the hydraulic oil from the master cylinder side is continuously supplied to the brake caliper. On the other hand, when the braking torque increases, the rotation of the tires is eventually locked, but at this time, the increase in the braking torque reaches a plateau, and the balance between the braking torque (reaction force) and the oil pressure in the pressure chamber is lost. The resultant displacement of the member is reduced and the check valve is closed. Therefore, immediately before the rotation of the tire is locked, the supply of the hydraulic oil to the brake caliper is stopped, and an increase in the braking torque is prevented. As a result, the tire is prevented from being locked.

In the present invention, in such antilock control,
If the coefficient of road surface friction changes during braking, the braking torque changes accordingly, and the position detecting rod is also displaced to try to adjust the braking pressure in the pressure chamber. At this time, the pressure responsive member attempts to make a relative displacement in a direction to compensate for the change in the pressure of the pressure chamber, but the throttle resistance interposed between the pressure chamber and the pressure responsive member causes a delay in the relative displacement,
As a result, the responsiveness of pressure chamber volume change (check valve opening / closing) to road surface change is enhanced.

(Embodiment) FIGS. 1 to 3 show a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an axle of a front wheel of a two-wheeled vehicle, reference numeral 2 denotes a front fork for supporting the axle 1, and reference numeral 3 denotes a brake disk for braking that rotates integrally with the front wheel. A bracket 7 projects rearward from the lower end of the front fork 2, and a base end of the link 5 is rotatably attached to the bracket 7 via a pin 8. A brake caliper 4 for braking the brake disc 3 is fixed to the link 5 via a bolt 6, and a cushion 9 made of rubber or the like abutting on the upper end of the brake caliper 4 is protruded rearward from the front fork 1. You. Further, a valve block 11A having a cylindrical outer shape is hingedly coupled to another bracket 10 projecting rearward above the cushion 9 of the front fork 1. A position detecting rod 11B protrudes freely from the valve block 11A, and its tip is a link 5
Hinged to the tip of

Inside the valve block 11A, a pressure regulator valve 11 that is opened and closed by an axial displacement of a position detection rod 11B is housed. The brake caliper 4 operates by receiving a supply of braking oil pressure from a master cylinder (not shown) to the brake cylinder 4A. A pipe 12 serving as a passage for the brake oil is provided via the pressure regulator valve 11. Note that 13
Is a pressure cut valve attached to the pressure regulator valve 11.

The internal structure of the pressure regulator valve 11 and the pressure cut valve 13 is shown in FIG. Pressure cut valve 13 located upstream
The passage 16 communicates the brake oil supplied from the master cylinder to the inlet port 14 in accordance with the pressure, and communicates with the upstream side of the pressure regulator valve 11 and the passage 17 that bypasses the pressure regulator valve 11 and reaches the downstream outlet port 15. A poppet 19 slid in a direction perpendicular to the inlet port 14 is housed in a valve chamber 18 formed facing the inlet port 14, and is opposed to the poppet 19. Thus, a seat 20 having a circular opening is formed in the valve chamber 18. A passage 16 is opened in the valve chamber 18 so as to face a side surface of the poppet 19, and is always in communication with the inlet port 14. Between the poppet 19 and the plug 40 at the back, pressure from the inlet port 14 is guided through a port 19A formed in the poppet 19, and a spring 21 for urging the poppet 19 toward the seat 20 is interposed. You. Spring 21
The repulsive force is weak enough that the poppet 19 functions as a check valve for the passage 17.

A sliding hole 22 is formed on the opposite side of the valve chamber 18 and the seat 20, and a spool 23 is slidably housed inside the sliding hole 22. The spool 23 is urged in the direction of the poppet 19 by a spring 24 interposed between the spool 23 and a plug 41 at the rear, and a rod 25 is fixed to the tip of the spool 23. The back surface of the spool 23 is released to the atmosphere, and a seal 26 is interposed between the spool 23 and the sliding hole 22. Also, the passage 17 is inserted into the sliding hole 22 in front of the spool 23.
Opens.

On the other hand, the pressure regulator valve 11 includes a poppet 28 and a seat 29 in a valve chamber 27 similar to the pressure cut valve 13, and a passage in the valve chamber 27.
16 opens. The poppet 28 is urged toward the seat 29 by a low-pressure spring 30 interposed between the poppet 28 and the plug 42, and functions as a check valve that closes the passage 16 from the upstream side. The inside and outside of the poppet 28 communicate with each other via a port 28A.

Further, the position detection rod 11 is slidably inserted into and held by a slide hole 31 formed on the opposite side of the valve chamber 27 with the seat 29 therebetween through a seal 38. And the position detection rod 11B
The passage 1 is inserted into a pressure chamber 31A provided in a sliding hole 31 in front of the insertion.
7 and an outlet port 15 connected to the brake cylinder 4A are opened.

A slide hole 32 is formed inside the insertion end of the position detection rod 11B, and a piston 34 as a pressure responsive member is housed inside this through a seal 35 slidably in the axial direction. A rod 33 protrudes from the piston 34 toward the poppet 28, a sliding hole 32 behind the piston 34 is released to the atmosphere, and a spring for biasing the piston 34 toward the poppet 28 is provided inside the sliding hole 32.
36 will be installed. A ring 37 is fixed by caulking to the tip of the sliding hole 32. The ring 37 functions as a stopper for the piston 34 and functions as a throttle resistance portion 37A in which a gap between the rod 33 penetrating the center communicates the inside of the slide hole 32 with the pressure chamber 31A.

 Next, the operation will be described.

Pressure regulator valve during normal running without braking operation
11 and the pressure cut valve 13 are in the state shown in FIG. That is,
Since no brake pressure is applied to the inlet port 14, the pressure cut valve 13 holds the poppet 19 via the rod 25 at the position where the springs 21 and 24 are balanced, and the inlet port 14 is connected to the passages 16 and 17.
Communicates with both. Further, the position detecting rod 11B connected to the tip of the link 5 is in the state of being most protruded from the valve block 11A by the spring force of the cushion 9.
As a result, the rod 33 separates from the poppet 28,
28 is urged by the spring 30 to sit on the seat 29 and pass
16 is closed, only passage 17 has inlet port 14 and outlet port 15
And communicates.

When the brake operation is performed from this state, the pressure in the valve chamber 18 of the pressure cut valve 13 and the sliding hole 22 is increased by the brake oil sent from the master cylinder to the inlet port 14, and the spool 23 that has released the back surface to the atmosphere is a spring. Rod against 24
Retreats with 25. Since the inside and outside of the poppet 19 are in communication through the port 19A, the pressures are equal, so that when the rod 25 is retracted, the poppet 19
, And sits on the seat 20 to close the passage 17.

On the other hand, the brake oil sent to the passage 17 before the closing is supplied to the brake caliper 4 through the outlet port 15 and the pipe 12, and exerts a braking torque on the brake disk 3. Then, the brake caliper 4 which has received the reaction force rotates the cushion 9 counterclockwise in FIG. 1 around the pin 8 while elastically deforming the cushion 9, and compresses the position detecting rod 11B.
As a result, the position detecting rod 11B retreats the poppet 28 from the sheet 29 via the rod 33 and moves the passage 16 to the exit port 15.
Communicate with

The brake pressure Pc at the time when the pressure cut valve 13 retracts the spool 23 to seat the poppet 19 on the seat 20
On the other hand, in the pressure regulator valve 11, the spring 36
Initially, a spring load of Fr = Pc × A (A: pressure receiving area of the piston 34) is initially set. The elasticity of the cushion 9 is set so that the sliding distance of the position detection rod 11B from the no-load state to the pressure Pc is equal to the separation distance between the rod 33 and the poppet 28 in the no-load state.

Under the above settings, the brake pressure becomes Pc
Until the brake oil of the master cylinder is supplied to the brake caliper 4 through the passage 17 until the pressure reaches Pc,
As soon as the pressure cut valve 13 closes, the pressure regulator valve 11
Is opened, and the brake pressure which increases thereafter is transmitted to the brake caliper 4 exclusively through the passage 16. Also, the piston 34 starts to retreat with the rod 33 against the spring 36 due to the increasing brake pressure.

By the way, assuming that the opening degree δ of the pressure regulator valve 11 in this state is brake pressure P = Pc + ΔP, the displacement of the position detecting rod 11B is Δχ, and the spring constant of the spring 36 is Ks, δ = Δχ− (A / Ks) .DELTA.P (1).

Here, as the brake pressure increment ΔP increases, the braking torque increases, and as a result, Δχ also increases.

On the other hand, the relationship between the braking torque T and the tire slip ratio S is shown in the graph of FIG. μ indicates the coefficient of friction between the road surface and the tire. When the braking torque T is increased on a normal road surface, the slip ratio of the tire suddenly increases at a certain value, and thereafter the braking torque T shows a slight decrease. Therefore, if the opening degree δ of the pressure regulator valve 11 is set to be approximately 0 near the maximum torque on the high μ road in the graph, the transmission of the pressure to the brake caliper 4 is cut even if the master cylinder is pressurized thereafter. It does not lead to tire locking. Specifically, the piston 33 is pushed back against the spring 36 due to the increase in the brake pressure, and the rod 33 is separated from the poppet 28 by being displaced in the opposite direction to the compression displacement of the position detection rod 11B,
The poppet 28 sits on the seat 29 and the pressure regulator valve 11
Becomes zero. The setting of the brake pressure value at which the pressure regulator valve 11 closes is performed by increasing the spring constant of the cushion 9 or by providing a stopper for restricting the rotational displacement of the link 5,
This is realized by suppressing the increase of the first term Δχ in the equation (1) and accelerating the increase of the second term with respect to the first term.

When the characteristics of the pressure regulator valve 11 are set as described above, the brake pressure increment ΔP on a low μ road or a wet road increases in accordance with the pressurization of the master cylinder, but the brake receiving the reaction force of the braking torque. The displacement Δχ of the position detecting rod 11B displaced together with the caliper 4 does not increase as much as the high μ road because the saturation of the braking torque occurs at a low torque. Therefore, the second term of the equation (1) becomes equal to the first term early, and the opening degree δ of the pressure regulator valve 11 becomes zero.
That is, since the pressure regulator valve 11 is closed at a low brake pressure on a low μ road or a wet road, the antilock function is sufficiently maintained even under such a condition that the tire is easily locked.

Next, when the braking torque suddenly changes, for example, when the vehicle enters from a high μ road to a low μ road during braking, the brake caliper 4 is moved to the cushion 9 by the reaction force of the braking torque suddenly decreasing.
And the displacement Δχ of the position detection rod 11B rapidly decreases. Following this, the piston 34 retreats, and the poppet 28 sits on the seat 29 to cut off the supply of the brake pressure, and at the same time, expands the volume of the pressure chamber 31A to increase the brake cylinder 4A.
It functions as a pressure reducing actuator that reduces the pressure acting on the actuator.

In order to lower the brake pressure, the piston 34 is urged by the spring 36 to slide forward in the slide hole 32. At this time, the throttle resistance portion 37A between the ring 37 and the rod 33 Resists outflow of brake oil in the sliding hole 32,
A time delay occurs in the displacement of the piston 34. This time delay, coupled with the high responsiveness of the position detecting rod 11B which is directly driven by the reaction force of the braking torque, brings about the function of instantaneously reducing the brake pressure with a good response to a sudden change in the friction coefficient μ. . In this case, the position detection rod 11B
The cross-sectional area of the position detection rod 11B is set in advance so that the expansion of the volume of the pressure chamber 31A due to the retreat causes a reduction in brake pressure necessary and sufficient to maintain the rotation of the tire.

On the other hand, conversely, when the vehicle enters the high μ road from the low μ road in the state where the anti-lock is operated, the rotational inertia torque of the wheel increases due to an increase in the rotational force of the tire due to a decrease in the slip ratio, The reaction force against the braking torque sharply increases, and the position detection rod 11B is largely displaced to the compression side. As a result, the volume reduction of the pressure chamber 31A functions as a pressure-intensifying pump, and immediately increases the brake pressure. At the same time, the rod 33 pushes the poppet 28 out of the seat 29 to supply high-pressure brake oil from the master cylinder to the brake caliper 4. To further increase the brake pressure. Again,
The piston 34 tries to retreat inside the sliding hole 32 due to the increased brake pressure, but the throttle resistance portion 37A resists the inflow of the brake oil into the sliding hole 32, so that the displacement of the piston 34 is delayed in time. , The brake pressure rises instantaneously.
For this reason, even when approaching from a low μ road to a high μ road, there is no possibility that the braking torque is insufficient, and the braking operation is efficiently performed over a short distance.

When the brake lever is released in an anti-lock operating state in which both the pressure regulator valve 11 and the pressure cut valve 13 are closed, the master cylinder is reduced in pressure, and the pressure of the brake caliper 4 which has become relatively high is increased by the poppet 28 and the poppet 28. 19 is opened with almost no resistance and returns to the master cylinder to return to the state before braking.

FIG. 4 shows a second embodiment of the present invention in which the bellows 50 and 52 are used in place of the spool 23 and the piston 34 to constitute the pressure regulator valve 11 and the pressure cut valve 13. The rod 25 is fixed to the poppet 19, A check valve 51 to which the rod 33 is fixed is used instead of the poppet 28. The orifice 37A is connected to the outside of the bellows 52 housed inside the sliding hole 32 and the pressure chamber 31.
A is formed through a plate-shaped sliding member 54 defining A. In this case, the operation principle is the same as that of the first embodiment, but since the bellows 52 and 54 are used, there is no danger that the brake oil leaks from the sliding holes 22 and 31, and the seals 26 and 38 are unnecessary. Therefore, there is no sliding friction, and further improvement in responsiveness can be expected.

The present invention is also applicable to a motorcycle rear wheel brake as shown in FIG. Here, the lower end of the brake caliper 4 is rotatably supported by the rear wheel axle 44,
The upper end is hingedly connected to the tip of a position detection rod 11B that protrudes freely from the valve block 11A. The base end of the valve block 11A is hinged to an intermediate portion of a swing arm 43 that supports the axle 44. Further, a spring 45 is interposed between the valve block 11A and the position detection rod 11B instead of the cushion 9. The structure of the pressure regulator valve 11 and the pressure cut valve 13 may be any of the above two embodiments. Thus, when the present invention is applied to a brake for a rear wheel, an antilock function having a high responsiveness can be obtained just like that for a front wheel.

(Effects of the Invention) As described above, the anti-lock brake of the present invention opens and closes the check valve of the hydraulic oil passage with the position detecting rod that is displaced by the reaction force of the braking torque and the pressure responsive member that responds to the brake pressure. In addition, since the pressure in the pressure chamber is changed to increase or decrease the hydraulic pressure (braking pressure) on the brake caliper side, the braking operation is performed with the optimum braking torque according to the road surface condition. In addition, because there is a throttle resistance that restricts the displacement of the pressure responsive member hydraulically, against sudden changes in braking torque,
The opening and closing of the valve and the change in the volume of the pressure chamber directly correspond to the displacement of the position detecting rod, and instantaneously generate a braking torque. For this reason, the responsiveness to a change in road surface conditions is high, and the braking operation can be performed very efficiently.

Also, there is no need to provide a separate mechanism for detecting the locked state of the tires, and the braking torque can be controlled according to the braking situation with a simple configuration. Can be saved significantly,
Significant weight reduction and space saving can be achieved.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a front wheel of a motorcycle showing a first embodiment of the present invention, FIG. 2 is a sectional view of a valve block, and FIG. 3 is a graph showing a relationship between a braking torque and a slip ratio.
FIG. 4 is a cross-sectional view of a valve block showing a second embodiment of the present invention, and FIG. 5 is a side view of a main part showing application of the present invention to a motorcycle rear wheel. 4 ... Brake caliper, 11B ... Position detection rod, 12
… Piping, 28… Poppet, 31A… Pressure chamber, 34… Piston, 37A …… Throttle resistance section.

Claims (1)

(57) [Claims] A brake caliper is mounted so as to be displaceable in accordance with a braking torque, a position detecting rod for detecting the displacement of the brake caliper is provided, and a master cylinder for supplying a hydraulic pressure to the brake caliper to brake a brake disc is provided. A pressure chamber in which the hydraulic pressure on the brake caliper side is provided in the middle of the hydraulic oil passage from the master cylinder to the brake caliper, and a position detecting rod displaced so as to expand and contract this pressure chamber in conjunction with the displacement of the brake caliper. A pressure response member elastically supported by the position detection rod and displaced with respect to the position detection rod in response to the pressure of the pressure chamber, wherein the pressure chamber has a displacement of the position detection rod and Hydraulic oil flow to the brake caliper according to the combined displacement obtained by combining the displacement of the pressure response member Provided with a check valve for opening and closing control, anti-lock brakes, characterized in that it comprises a throttle resistance for regulating the displacement speed of intervention to the pressure responding member hydraulically between the pressure responsive member and the pressure chamber.